This article was downloaded by: [Hanyang University]
On: 10 May 2013, At: 01:50
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,
37-41 Mortimer Street, London W1T 3JH, UK
Critical Reviews in Solid State and Materials Sciences
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/bsms20
Carbon Nanostructures in Lithium Ion Batteries: Past,
Present, and Future
a
Indranil Lahiri & Wonbong Choi
a b
a
Nanomaterials and Device Lab, Department of Materials Science and Engineering,
University of North Texas, Denton, TX, 76203, USA
b
WCU Program Department of Energy Engineering, Hanyang University, Korea
Published online: 10 Apr 2013.
To cite this article: Indranil Lahiri & Wonbong Choi (2013): Carbon Nanostructures in Lithium Ion Batteries: Past, Present, and
Future, Critical Reviews in Solid State and Materials Sciences, 38:2, 128-166
To link to this article: http://dx.doi.org/10.1080/10408436.2012.729765
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to
anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representation that the contents
will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should
be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims,
proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in
connection with or arising out of the use of this material.
Critical Reviews in Solid State and Materials Sciences, 38:128–166, 2013
c Taylor and Francis Group, LLC
Copyright ISSN: 1040-8436 print / 1547-6561 online
DOI: 10.1080/10408436.2012.729765
Carbon Nanostructures in Lithium Ion Batteries:
Past, Present, and Future
Indranil Lahiri1 and Wonbong Choi1,2,∗
1
Downloaded by [Hanyang University] at 01:50 10 May 2013
Nanomaterials and Device Lab, Department of Materials Science and Engineering, University of North
Texas, Denton, TX 76203, USA
2
WCU Program Department of Energy Engineering, Hanyang University, Korea
Advent of nanotechnology has generated huge interest in application of carbon-based nanomaterials as a possible replacement for conventionally used graphite as anode of Li-ion batteries.
Future Li-ion batteries demand high capacity, energy, power, and better safety, while graphite
falls short of fulfilling all these necessities. Inspired by high conductivity, flexibility, surface
area, and Li-ion insertion ability, a number of nano carbon materials, individually or as a
composite, have been studied in detail to identify the best suitable material for next-generation
energy storage devices. Many of these nano-C-based structures hold good promise, although
issues like density of nanomaterials and scalability are yet to be addressed with confidence.
This article aims to summarize the major research directions of nano-C materials in anodic
application of Li-ion batteries and proposes possible future research directions in this widely
studied field.
Keywords carbon nanotube, graphene, fullerene, core-shell structure, porous structure, electrochemical properties
Table of Contents
1. INTRODUCTION ................................................................................................................................................ 129
2. LITHIUM ION BATTERY: BACKGROUND ....................................................................................................... 130
3. NANOSTRUCTURED MATERIALS FOR LI-ION BATTERY: PROS AND CONS ............................................. 132
4. NANOSTRUCTURED CARBON AS ANODE IN LI-ION BATTERY .................................................................. 136
4.1. Zero-Dimensional Carbon: Fullerene and its Composites ................................................................................... 136
4.2. One-Dimensional Carbon: Carbon Nanotube and its Composites ........................................................................ 137
4.2.1. CNT-based Composite Electrodes ......................................................................................................... 137
4.2.1.1. CNT-Metal Composite Electrodes ........................................................................................... 137
4.2.1.2. CNT-oxide composite electrodes ............................................................................................. 139
4.2.1.3. CNT-Polymer Composite Electrodes ........................................................................................ 142
4.2.2. Binder-free CNT-based Electrodes ........................................................................................................ 143
4.3. Two-Dimensional Carbon: Graphene and its Composites ................................................................................... 145
4.3.1. Graphene Electrodes ............................................................................................................................ 145
4.4. Graphene-Metal Oxide Composite Electrodes ................................................................................................... 147
4.4.1. Other Composite Electrodes with Graphene ........................................................................................... 150
4.5. Nanostructured C-C Composites ...................................................................................................................... 150
4.6. Core-Shell Structures ..................................................................................................................................... 153
∗
E-mail: [email protected]
128
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
129
5. OTHER CARBON-BASED ANODES .................................................................................................................. 155
5.1. Graphite-based Composites with Different Nanomaterials ................................................................................. 155
5.2. Spheroidal Carbon-based Anodes .................................................................................................................... 156
5.3. Porous Carbon-Based Electrodes ..................................................................................................................... 157
6. SCOPE AND FUTURE ........................................................................................................................................ 158
ACKNOWLEDGMENTS .......................................................................................................................................... 160
Downloaded by [Hanyang University] at 01:50 10 May 2013
REFERENCES ......................................................................................................................................................... 160
1. INTRODUCTION
The research field of alternate energy generation and efficient
energy storage has seen immense growth in recent years, mainly
owing to increasing concerns about depleting hydrocarbonbased energy resources, environmental pollution caused by hydrocarbon based fuels, and global warming issues.1 In an era,
when clean and renewable energy generation is being sought for
achieving an energy-efficient and low-carbon status,2,3 energy
transmittance, and storage plays vital roles. Escalating usage of
hybrid/all-electric automobiles, efficient application of myriad
of portable electronic devices, and fulfilling the needs of medical implants (such as artificial hearts) depend highly on implementation of new science and technology in next-generation
energy storage devices, such as advanced rechargeable batteries and supercapacitors.4,5 World rechargeable battery market
was $36 billion in 2008 and is expected to grow to $51 billion in 2013 and to $78 billion in 2020.6,7 There are mainly
three types of rechargeable batteries dominating in the market: Ni-Cd, Ni-MH (Ni-metal hydride), and Li-ion batteries.
Li-ion batteries have 75% share of the portable rechargeable
batteries and show a very good growth rate. On the contrary,
Ni-Cd and Ni-MH are showing declining growth rates due to
stringent restrictions about “Cd” usage for environmental issues and a strong competition from Li-ion batteries for higher
gravimetric and volumetric energy densities (150 Wh/kgcell and
350 Wh/Lcell , respectively).6,8 Thus, research on development
of advanced Li-ion batteries has attracted huge attention from
the scientific community, especially in the last decade. Figure 1a
echoes this trend in terms of number of publications. It may be
noted at this point that a plug-in hybrid electric vehicle (PHEV)
needs a 16 kWh battery,9 which can be more efficiently met by
fewer Li-ion batteries, compared to other types of secondary
batteries.
Li-ion battery technology mainly deals with achievement of
higher energy density, longer life, lower charging times, and
better operational safety. To address these issues, the scientific
community has focused either in development of new materials
for electrodes and electrolytes or on demonstrating new designs.
Nanotechnology played a dominant role in the development of
new electrode materials. Well-established use of graphite as a
Li-ion battery anode, due to its excellent stability and longer life,
has invoked special research interest on carbon nanostructures.10
Different forms of nanostructured carbon materials, from 0dimensional fullerenes to 1-dimensional carbon nanotubes and
2-dimensional graphene, were experimented as anode for future Li-ion batteries. Figure 1b shows a year-wise publication
list of such applications showing an increasing trend of using
carbon nanostructures in Li-ion batteries. The figure also emphasizes increasing application of one- and two-dimensional
carbon nanostructures—either individually or as a composite,
in advanced Li-ion batteries. Apart from these nanostructures,
carbon has also found immense importance in core-shell kind
of structures and as porous structures, in anodic application of
lithium ion batteries.
As mentioned by Scrosati et al. in one of their recent publications,11 evolution of Li-ion battery technology is so fast
that it may soon become very difficult to track its progress.
However, for deciding future directions of research, it is extremely necessary to develop an idea about state-of-the-art and
know about the future challenges. Hence, timely review of the
relevant topics in Li-ion battery technology is of high importance. Reviews have been published regularly in the last ten
years to summarize developments in this emerging field of energy engineering.12–16 Due to extensive increase in volume of
publications in Li-ion battery technology, especially, involving
application of nanomaterials, it is now required to summarize
the advances in specialized fields. Fulfilling this demand, reviews have been published periodically regarding development
in highly focused areas of Li-ion battery research.17–20 However, most reviews, summarizing the developments in anode
materials, were published almost 7–8 years back.21,22 Considering huge volume of research and publications in the anodic
material developments of Li-ion battery, it is now necessary
to publish reviews of much specialized topics, such as carbon
nanostructures in Li-ion battery anode. Reviews on application
of carbon-based materials (not nanomaterials) were also published almost ten years ago.23,24 In 2009, Kashkhedikar et al.
summarized lithium storage in carbon nanostructures, with special emphasis on structural understanding and lithium storage in
different graphitic or partially graphitic structures.25 However, a
wide variety of carbon nanostructures, fullerene, graphene, carbon nanotubes, their composites with other materials, core-shell
Downloaded by [Hanyang University] at 01:50 10 May 2013
130
I. LAHIRI AND W. CHOI
FIG. 1. Year-wise publication plots for (a) Li-ion battery (English language only) and (b) application of zero- (fullerene),
one- (carbon nanotubes and nanowires), and two-dimensional (graphene) carbon nanostructures in Li-ion batteries. (Source:
scopus.com.) (Color figure available online.)
structures containing nano-carbon coating, mesoporous carbon,
etc., have been used in anodic application of Li-ion batteries. In
this present scenario, we present here a comprehensive review
of the studies involving carbon nanostructures in Li-ion battery.
This article is aimed to provide a thorough insight into the overall development of carbon-based nanomaterials for application
in Li-ion battery and highlight the underlying challenges that
need to be addressed in near future.
2. LITHIUM ION BATTERY: BACKGROUND
Application of lithium in batteries has been motivated by its
unique properties. Li is the most electropositive (−3.04 V vs.
hydrogen electrode) and also the lightest (density = 0.53 g/cm3)
metal, known to mankind.4 These exciting electrochemical
and physical properties ensure high voltage, energy density
(Figure 2), and power density in the battery. Li-ion battery,
with graphitic anode, offers a nominal cell voltage in the range
of 3.0–3.7 V, while Ni-Cd and Ni-MH batteries show much
lower voltage (1.2–1.5 V). These advantages of Li were appreciated in early 1970s, although as a primary (non rechargeable)
battery.26 However, dendritic growth of Li metal, leading to
shorting of electrodes and finally, to thermal runaway, was soon
pointed out to be the main hindrance to further development
of this battery technology. Extending the concept of “rocking
chair technology” already being used in Ni-MH batteries,27 Li
metal was substituted by a Li insertion compound, leading to
the development of Li-ion batteries.28,29 Sailing on its favorable
electrochemical and physical properties and powered by the
safety offered by Li insertion compounds, Li-ion battery soon
outperformed other players in the market to occupy 63% share
of battery market in 2001.4
A Li-ion battery consists of a positive electrode (cathode)
as source of Li+ ion, non aqueous liquid electrolyte, polymeric
separator, and negative electrode (anode), which can accept Li+
ions. Most popular choices for cathode and anode are layered
LiCoO2 and graphite, respectively.30 The electrolyte is generally an organic liquid containing lithium salt—mostly, 1M
LiPF6 dissolved in a mixture of ethylene carbonate-diethylene
carbonate (EC-DEC) or ethylene carbonate-dimethyl carbonate
(EC-DMC). The separator ensures no direct contact between the
FIG. 2. A comparison of different battery technologies, based
on their volumetric and gravimetric energy densities. (Reprinted
with permission from Tarascon and Armand4 Copyright 2001:
Nature Publishing Group.) (Color figure available online.)
Downloaded by [Hanyang University] at 01:50 10 May 2013
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
131
FIG. 3. Schematic representation of charging and discharging processes in Li-ion battery. (Color figure available online.)
electrodes, by allowing ions but blocking movement of electrons
through it. During charging, Li+ ions deintercalate from the
source LiCoO2 structure, pass through the electrolyte to reach
the anode, and intercalate between different layers of graphite.
During discharging, the process reverses and electron flows
through the outer circuit to perform electrical work. Figure 3
shows schematic representations of the charging and discharging processes in a typical Li-ion battery. The total reaction and
the anodic reaction, based on intercalation and deintercalation
of Li+ ion, are given by the following reactions, respectively:24
LiCoO2 + yC ↔ Li1−x CoO2 + Lix Cy
yC + xLi+ + xe− ↔ Lix Cy .
[1]
[2]
voltage, ∼0.1 V, as compared to most other candidate materials,
e.g., Si (0.5–1.0 V), Ge (0.7–1.2 V), etc.8,33 This low potential ensures a high voltage output of the Li-ion battery (using
graphite as anode), which is one of the strongest advantages
of Li-ion batteries over Ni-Cd and Ni-MH batteries. Secondly,
materials offering higher specific capacities (e.g., Si, Sn, Ge)
also show extremely high volume expansion/contraction during lithiation/delithiation (∼300–400%).32,34,35 On the contrary,
graphitic carbon is known to show a negligible (∼10%) expansion upon lithiation. Volume expansion could be related to the
rise in number of atoms upon lithiation viz. LiAl (100% rise),
Li4.4 Sn (440% rise), etc., as compared to LiC6 (16% rise) for
graphitic carbon. Very high volume change leads to pulverization and, finally, to breakdown of the electrode structure, which
For both the reactions, forward direction represents charging
and backward direction indicates discharging. In both Equations
(1) and (2), “C” can be replaced by any metal, which react with
or intercalate Li+ ions. Equation (2) is further used to calculate
theoretical capacity of anode (graphite in the present example)
by the following equation:31
QC = (x96500)/(3.6 y MC ),
[3]
where QC is the theoretical specific capacity of “C” in mAh/g
and MC is its molecular weight.
It is well known that graphite forms a compound LiC6 in the
Li-ion battery.24 Thus, theoretical specific capacity of graphite
can be calculated as 372 mAh/g. It is important to mention
here that practical achievable capacity from a graphite anode
is much less(∼300–310 mAh/g).24 Many elements are found to
offer higher specific capacities, at least theoretically, as compared to graphite (Figure 4).32 Wide acceptance of graphite as
the anode material for Li-ion batteries can be related to couple of important factors. First, graphite operates at a very low
FIG. 4. Theoretical specific capacities (gravimetric and volumetric) of selected elements in order of increasing volumetric
capacity.) (Color figure available online.)
132
I. LAHIRI AND W. CHOI
Downloaded by [Hanyang University] at 01:50 10 May 2013
is well known for materials like Si, Sn, etc. Graphite, on the
other hand, provides a highly stable structure and long cycle life
of the battery. These advantages of graphitic carbon over other
candidate materials make them the most popular and industrially
accepted anode material for commercial Li-ion batteries.
Charging/discharging process in Li-ion batteries consists
of mainly three types of reactions: (i) diffusion of Li ions
within solid electrode materials; (ii) charge transfer at electrodeelectrolyte interface; and (iii) movement of Li+ ion in the electrolyte.36 Out of these three steps, solid state diffusion of Li ions
is known as the rate-controlling step for Li-ion batteries as it
restricts the rate of charge/discharge, leading to a low power
output.30,36 The characteristic time for Li ion diffusion can be
expressed as a function of diffusion coefficient of Li ions and
the diffusion length as following:
τ=
L2ion
,
DLi
[4]
where Lion is the diffusion length and DLi is the diffusion coefficient of Li ions.
It is immediately evident from Equation (4) that a faster diffusion can be achieved in a system with higher diffusion coefficient and lower diffusion length. Diffusion coefficient of Li ions
in most electrode materials is very low (10−7–10−11 cm2/s)37
and, thus, diffusion length becomes important. Nanostructured
materials appear to be necessity at this point, as these can reduce the diffusion length substantially and, hence, are capable
to improve rate performance of Li ion batteries.
3. NANOSTRUCTURED MATERIALS FOR LI-ION
BATTERY: PROS AND CONS
Before moving further, it is important to understand specific
advantages and limitations of using nanostructured materials
in electrodes of Li-ion batteries. Several publications have discussed the effects of nano size in electrode applications for
Li-ion batteries.8,25,30,36,37 A very brief discussion on pros and
cons of using nano materials in Li-ion batteries is presented
here.
Nano materials offer several advantages over their bulk counterparts, in Li-ion battery electrode application, as follows. (i)
As could be observed from Equation (4), reduced dimensions
of nanomaterials offer shorter diffusion lengths. Since diffusion
time is proportional to square of diffusion length, nanomaterials show substantial reduction in time to diffuse, leading to
significant improvement in the rate capability of Li-ion batteries. (ii) High surface area of nanomaterials ensures more
reaction sites and, thus, more Li ions can be stored in active
electrode materials. This increases gravimetric capacity of the
electrode. (iii) Often, nanomaterials show enhanced electron
transport within the particles, improving overall kinetics of the
charge/discharge process.37,38 Apart from these three main benefits of using nanostructured materials as electrode in Li-ion
batteries, nanomaterials often show other advantages like (iv)
occurrence of some specific electrode reactions, which are not
observed for their micro-sized counterparts;36,37,39 (v) change in
chemical potentials of Li ion and electrons leading to modified
electrode potential;40,41 and (vi) extended solid solubility limits
at nanoscale.42,43 These features of nanoscale materials may also
be used beneficially for electrode applications in Li-ion batteries. Further, pulverization (due to expansion/contraction of the
electrode material during lithiation/de-lithiation) is known to be
a serious problem for many potential materials, e.g., Si, SnO2 ,
etc., in their bulk forms. Nanostructures of these materials have
shown good promise to better accommodate such lithiation induced strain, which has been successfully demonstrated for Si
nanowire anodes.34,37 Thus, nanomaterials appear to be promising for long structural stability of the electrodes, too.
In spite of high potential of nanomaterials for application
in Li-ion batteries, their industrial scale application is still restricted by their limitations. While high surface area of nanomaterials brings in the benefits of more Li-ion intake and,
hence, more capacity, it also carries its own drawbacks. Solid
electrolyte interphase (SEI), formed on the electrode surfacethrough reaction between electrode material and electrolyte,
hinders ionic mobility during charge-discharge and contributes
towards irreversible capacity loss. Nanomaterials have high surface area and more unwanted reaction sites, which promote SEI
formation and significant increase in irreversible capacity loss
of the electrode.21 Minimizing SEI formation and irreversible
capacity loss have thus been focus of many researchers and are
being considered as important milestones to be achieved for
successful implementation of nanomaterials in Li-ion battery.
Further, density of nanomaterials being low, electrode volume
increases, leading to reduced volumetric capacity (and energy
density).30 Moreover, synthesis routes of most of the nanomaterials are often complex and extensive, making the products
expensive, even after industrial scale upgradation.
Banking on the advantageous features of nanomaterials and
carbonaceous materials, especially graphitic carbon, great deals
of research efforts were concentrated on application of nanostructured carbon materials in anodes of Li-ion batteries. Different forms of nano carbon materials have been used in such
applications, viz. zero-dimensional fullerene, one-dimensional
carbon nanotubes, two-dimensional graphene, and composites
of these with other materials. Nano-carbon has also attracted
attention in the forms of core-shell structures and mesoporous
materials. In the forthcoming sections, brief descriptions of such
research efforts will be presented. Table 1 summarizes some research efforts involving application of nanostructured carbon
materials as electrode in Li-ion batteries and as discussed in
this article. Considering the huge publication volume, the table
could accommodate only a fraction of all research efforts. Further, it may also be noted here that reversible specific capacity,
which is the only property reported in this table, is one of the
major properties of the electrodes. However, many other properties, such as irreversible capacity, energy density, stability, rate
capability etc. are important for electrode materials of Li-ion
batteries. This table should be used only as an indicator of the
133
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
TABLE 1
Summary of application of carbon nanostructures in anode of Li-ion batteries
Downloaded by [Hanyang University] at 01:50 10 May 2013
Materials used as anode
C60 derived polymer
Fullerene coating on Li metal
Fullerene coating on Si thin film
MWCNT, with CBa and PTFEb
MWCNT, with ABc and PVDFd
MWCNT (raw, closed ends), with AB
and PVDF
MWCNT (purified), with AB and PVDF
MWCNT, with CB and PVDF
MWCNT (purified), with AB and PVDF
MWCNT (purified)-28 wt% Sn2 Sb, with
AB and PVDF
MWCNT (purified)-56 wt% Sn2 Sb, with
AB and PVDF
MWCNT (purified)-36 wt.% Sb, with
AB and PVDF
MWCNT (ball milled)-Bi, with CB and
PVDF
MWCNT (ball milled)-Sb, with CB and
PVDF
MWCNT (purified)-Sn/SnNi, with CB
and PVDF
MWCNT (purified)-Si powder, 1:1
weight ratio
Cage like CNT-Si particles
SWCNT-graphite-Si with CB and PVDF
Porous Si film on SWCNT film
Free-standing CNT-Si film
Si nanoparticles grafted on CNTs
Nano Si droplets on vertically aligned
MWCNTs, with CB and sodium
carboxymethyl cellulose
ONTC∗
MWCNT-SnO2 nanoparticle (inside
tubes), with AB and PVDF
MWCNT-SnO2 nanoparticle (on
surface), with CB and PVDF
Cross-stacked MWCNTs, decorated with
SnO2 nanoparticles
MnO2 nanoflakes attached with CNTs,
with CB and PVDF
CuO-CNT nanomicrospheres, with CB
and PVDF
Cu-Cux Oy -SWCNT
Directly grown MWCNTs on Cu current
collector
Ultra-thin alumina coated MWCNTs,
directly grown on Cu current collector
Specific Capacity (mAh/g)
Current rate
340
80–100
3000
180
350–780
125
NA
0.2–0.5 C∗
0.1 mA/cm2
10 mA/g
20 mA/g
C/48
220–780
200–250
280
380–400
20 mA/g
50 mA/g
40 mA/g
40 mA/g
56
480–500
40 mA/g
58
462
50 mA/g
59
300–400
25 mA/g
62
200–300
25 mA/g
62
400–450
50 mA/g
60
1770–1200
50 mA/g
64
1400–950
900
2221
∼2000
1000
2050 (after 25 cycles)
0.156 mA/cm2
0.250 mA/cm2
0.1 C
0.1 C
500 mA/g
100 mA/g
65
515
506 (after 40 cycles)
0.5 mA/cm2
37.2 mA/g
77
400 (after 100 cycles)
100 mA/g
79
850
0.1 C
80
600
200 mA/g
83
500
0.1 C
85
223
900
767
1180
1080
Reference
46
50
51
53
54
55
57
58
58
66
71
70
72
73
78
86
50 C
101
372 mA/g
1116 mA/g
102
112 mA/g
1116 mA/g
(Continued on next page)
134
I. LAHIRI AND W. CHOI
TABLE 1
Summary of application of carbon nanostructures in anode of Li-ion batteries (Continued)
Materials used as anode
Downloaded by [Hanyang University] at 01:50 10 May 2013
Graphene nanosheet (GNS) with PTFE
Graphene nanosheet (GNS)-CNT, with
PTFE
Graphene nanosheet (GNS)-C60 , with
PTFE
Oxidized graphene nanoribbons (GNR),
with CB and PVDF
N-doped graphene, grown on Cu foil
Pristine graphene, grown on Cu foil
N-doped GNS, with CB and PVDF
B-doped graphene, with CB and PVDF
Honeycomb structure of reduced
graphene oxide (RGO)
Reduced holey graphene oxide
SnO2 nanoparticle-GNS nanoporous
electrode
SnO2 nanoparticles dispersed on SLG,
with CB and PVDF
Self-assembled layered SnO2
naoparticle-graphene film
Alternate SnO2 -graphene layers
CuO urchin-like nanoparticles in 3-D
network of graphene, with AB and
PVDF
CuO-GNS alternate layers, with AB and
PVDF
RGO-Fe3 O4 nanoparticles, with CB and
PVDF
GNS- Fe3 O4 nanoparticles, with CB and
PVDF
RGO-Fe2 O3 nanoparticles, with PTFE
Nanostructured TiO2
(rutile/anatase)-graphene, with CB and
PVDF
RGO-Mn3 O4 nanoparticles, with CB and
PVDF
Graphene-Co3 O4 nanoparticles, with AB
and PVDF
Graphene-Co3 O4 nanosheets, with AB
and PVDF
Grapehene-MoS2 , with AB and PVDF
Amorphous carbon-MoS2 , with AB and
PVDF
Functionalized graphene sheet-S
nanoparticles, with CB and PVDF
Specific Capacity (mAh/g)
Current rate
Reference
540 (initial) – 300 (after 20 cycles)
730 (initial) – 500 (after 20 cycles)
50 mA/g
111
800
0.1 mA/cm2
112
0.05 mAh/cm2
0.03 mAh/cm2
900
∼1300 (after 30 cycles)
235
1150 (after 50 cycles)
0.005 mA/cm2
113
42 mA/g
50 mA/g
25,000 mA/g
50 mA/g
113
165 (after 500 cycles)
80
570 (after 30 cycles)
5000 mA/g
10,000 mA/g
50 mA/g
119
558 (after 50 cycles)
264 mA/g
125
∼600
10 mA/g
126
∼800 (after 150 cycles)
600 (up to 100 cycles)
150
100 mA/g
65 mA/g
6400 mA/g
127
∼650 (after 100 cycles)
70 mA/g
130
929
192
1102
474
1027
800
160–180
0.05 C
10 C
100 mA/g
1600 mA/g
100 mA/g
800 mA/g
1C
131
900
390
935 (after 30 cycles)
40 mA/g
1600 mA/g
50 mA/g
137
1162
931
250
912 (after 100 cycles)
445 mA/g
4450 mA/g
10000 mA/g
100 mA/g
138
505
1680 mA/g
144
784(initial) – 600 (after 20 cycles)
115
118
124
129
132
133
135
139
142
143
135
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
TABLE 1
Summary of application of carbon nanostructures in anode of Li-ion batteries (Continued)
Materials used as anode
CNFs grown on Si nanoparticles, with
styrene–butadiene rubber and CMCe
CNF core-Si shell structure
Carbon coated Si nanowire array film
Si nanoparticles wrapped by carbon tube
Downloaded by [Hanyang University] at 01:50 10 May 2013
TiC/C/Si nanofiber composite
SnO2 core-CNT shell, with CB and
PVDF
CNT@SnO2 -Au nanocable, with CB and
PVDF
Sn-core – C-sheath coaxial nanocable,
with CB and PVDF
Mesoporous Sn-core – C-shell, with CB
and CMC
Coaxial MnO2 -CNT array
CNT core-porous TiO2 sheath
composite, with CB and PVDF
RuO2 -C self wound nano membrane,
with CB and PVDF
CNT encapsulated CNFs, with PVDF
CNT modified carbon fiber paper
Mesoporous carbon-20%MWCNT
CNTs in situ grown on GNS, with CB
and PVDF
CNFs grown on GNS, with CB and
PVDF
Sn@CNTs, rooted in graphene, with CB
and PVDF
Spheroidal C coated Si composite
electrode, with CB and PVDF
Carbon nanocages with nano-graphene
shell,
Nanographene constructed hollow C
sphere, with CB and PVDF
Ordered mesoporous carbon, with PTFE
Hierarchically porous carbon monoliths,
with PVDF
Specific Capacity (mAh/g)
Current rate
Reference
1051 (after 20 cycles)
100 mA/g
155
1800 (after 55 cycles)
1326 (after 40 cycles)
1300 (after 100 cycles)
800 (after 300 cycles)
3000
1730
1500
586
500 mA/g
150 mA/g
240 mA/g
2750 mA/g
840 mA/g
4200 mA/g
8400 mA/g
0.5 C
156
467
392
∼350
3600 mA/g
7200 mA/g
1600 mA/g
164
680
220
500 (after 15 cycles)
406
244
1000 (after 20 cycles)
700
410
546 (after 50 cycles)
380
94
573
520
667
329
189
1160
828
686
594
1489 (after 20 cycles)
0.3 C
4.5 C
50 mA/g
50 mA/g
3000 mA/g
C/16
1C
C/5
0.05 mA/cm2
2C
30 C
0.2 C
2C
0.12 mA/cm2
1.2 mA/cm2
6.0 mA/cm2
100 mA/g
1000 mA/g
2000 mA/g
5000 mA/g
100 mA/g
165
574 (after 60 cycles)
58
600
200
1100
540
260
70
157
160
162
163
166
168
169
170
147
148
149
151
152
154
185
153
100 mA/g
10000 mA/g
186
C/5
10 C
187
100 mA/g
188
1C
10 C
60 C
(Continued on next page)
136
I. LAHIRI AND W. CHOI
TABLE 1
Summary of application of carbon nanostructures in anode of Li-ion batteries (Continued)
Materials used as anode
Sn particles encapsulated in porous
multichannel carbon microtubes,
with CB and PVDF
C-Si granule electrode, with binder
α-Fe2 O3 nanocrystals inside hollow
amorphous carbon structure, with AB
and CMC
Specific Capacity (mAh/g)
Current rate
Reference
775
570
295
1950
1590
870
722 (after 220 cycles)
100 mA/g (∼C/2)
2C
10 C
C/5
1C
8C
2C
194
195
197
∗
C-rate convention: 1C rate is defined as the current rate required to dis(charge) the full theoretical capacity in 1 h
– CB is carbon black
b
– PTFE is polytetrafluoroethylene
c
– AB is acetylene black
d
– PVDF is polyvinylidene fluoride
e
CMC – carboxymethyl cellulose
∗∗
ONTC is ordered nanostructured tin-based oxides/carbon composite
NA – Not available in the literature
Downloaded by [Hanyang University] at 01:50 10 May 2013
a
research trends. For detailed understanding, readers are referred
to the corresponding published articles.
4. NANOSTRUCTURED CARBON AS ANODE IN LI-ION
BATTERY
4.1. Zero-Dimensional Carbon: Fullerene and its
Composites
Both C60 and C70 fullerenes were studied for understanding
their Li storage capacities. It was observed that a maximum of
1 Li per 5 C can be accommodated in C60 molecule,44 which is
a better situation than graphite (LiC6 ). Hydrogenated fullerenes
were found to offer higher Li-storage capacity and better stability.45 The capacity was observed to be dependent on the degree
of hydrogenation. Fullerene-derived polymers also have shown
good potential stability and high stability, with specific capacity
of 340 mAh/g.46
Fullerenes found more applications as composite anode,
mostly with Si thin- or thick-film anodes47–49 and with Li metal
anode.50 In one such research effort, C60 was deposited on a
Li metal anode by three different techniques—radio frequency
(RF) magnetron sputtering, plasma assisted thermal evaporation, and ion beam-assisted thermal evaporation.50 Irrespective
of the deposition process, cyclic performance of the anode was
found to be improved, as compared to pure Li metal anode.
While Li metal anode showed a sharp fall in capacity after
20 cycles and almost nil capacity within 25th cycle, fullerenedeposited Li metal anodes offered quite stable behavior, at least
up to 30 cycles. Quick capacity degradation of Li metal anodes
can probably be related to dendrite formation and shorting of
electrodes. Fullerene coating on Li metal inhibits the dendrite
formation tendency of the anode. Although specific capacity
of the fullerene-coated Li metal anode was not very high, it
still showed a route to avoid harmful effects of dendrite formation. Fullerene coating, moreover, has shown stabilizing effect,
when applied on Si thin film anodes.51,52 Research on fullerene
coated Si anode was found to be limited to one research group
only206 and has not been followed up by other groups. Fullerene
film could be applied on a Si thin film either by sputtering
or by plasma assisted evaporation methods. Irrespective of the
methods of synthesis, this hybrid Si-fullerene thin-film anode
structure was found to offer much lower first cycle irreversible
capacity loss, better stability for longer cycles (tested up to
50 cycles), and higher specific capacity (2800–3000 mAh/g),
in comparison with bare Si thin film electrodes (Figure 5).
FIG. 5. Discharge capacities of Si thin film electrodes in Liion battery application, with and without fullerene coating.
(Reprinted with permission from Arie et al.51 Copyright 2009:
Springer.)
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
Downloaded by [Hanyang University] at 01:50 10 May 2013
Superior performance of this hybrid anode can be attributed
to three specific advantages offered by the fullerene coating:
enhanced Li-ion kinetics, passive layer formation on Si (and
thus, protecting it from undesirable reactions with electrolyte),
and introduction of a compressive stress on Si, which mitigates
volume expansion problem of Si.
Albeit some favorable feedbacks, fullerene-based anodes
were not studied in much detail, because of huge advantages
expected from two other carbon allotropes: carbon nanotube
and graphene. As shown in Figure 1, these two carbon nanostructures have been studied extensively, for possible application
in Li-ion battery electrode.
4.2. One-Dimensional Carbon: Carbon Nanotube and its
Composites
Interest in carbon nanotubes (CNT) for Li-ion battery application began during 1999–2000. Initial studies, involving multiwalled carbon nanotubes (MWCNTs) as the active component
in negative electrode of Li-ion batteries, were not encouraging
enough.53,54 In 2000, Beguin et al. proposed developing new carbon material based anode in Li-ion batteries as a replacement
of conventionally used graphite electrodes.54 Comprehending
the limitations of high irreversible capacity loss shown by hard
carbon, which was presumed to be an alternative of graphite at
that time, they suggested application of MWCNTs as the active
material of the negative electrode in Li-ion battery. MWCNTs
were expected to show high Li+ ion insertion capacity, both in
the mesoporous structure and in the inter-layer space. Contrary
to the expectation, MWCNTs prepared through different routes
were found to offer reversible capacity in the range of 350 –
780 mAh/g and very high irreversible capacity of 570–1080
mAh/g. Such high irreversible capacity loss, along with appreciable hysteresis, compelled the authors to conclude that MWCNTs could not have any application in Li-ion batteries. In spite
of this hitch, many other research groups studied the structural
features of MWCNTs, e.g., purified, unpurified, closed end,
etc., to improve performance of MWCNT-based negative electrodes in Li-ion batteries. (1; 2; 3) However, results from these
studies were not very much exciting (Table 1). In spite of the
theoretical advantages of high surface area, excellent electrical
conductivity, robust structure of MWCNTs, such kind of notso-encouraging results were really unexpected and compelled
the scientific community to analyze the failures and to come
up with novel solutions. Various approaches were followed to
combat this situation, which will be discussed in the following
sub-sections.
4.2.1. CNT-based Composite Electrodes
An immediate solution to improve performance of CNTbased electrodes, as envisioned, was the use of composite electrodes and many research efforts were concentrated on developing new composite structures. Different materials were
137
used/mixed with CNTs to prepare composite electrodes. CNTbased composite electrodes are further classified here into following categories for better comprehension.
4.2.1.1. CNT-Metal Composite Electrodes. Among the
metals, Si and Sn and/or their compounds were most promising due to their very high theoretical specific capacity
(Figure 4). Thus, most of the researches focusing on application
of CNT-metal composite electrode for Li-ion battery had studied
either of these two metallic elements as additive—individually
or along with other materials. In one of those early studies,
nanocomposites of CNTs with Sn2 Sb nanoparticles were used.58
The composite nanostructure was synthesized by KBH4 reduction of SnCl2 and SbCl3 precursors in presence of CNTs. Addition of Sn2 Sb was found to increase reversible capacity of
the anode by 1.4–1.8 times, depending on the amount of Sn2 Sb
alloy nanoparticles. Higher amounts of nanoparticles promoted
more capacity for the anode, clearly indicating the beneficial
effects of Sn2 Sb addition. Capacity loss (0.35%/cycle, over 80
cycles) of the composite anode was comparable to that of bare
MWCNT anodes (0.44%/cycle, over 80 cycles). In a similar
study by the same group, MWCNT-Sb composite electrode was
found to offer little lower capacity and a bit higher capacity fading rate per cycle, as compared to MWCNT-Sn2 Sb electrode.59
Following the same trend, MWCNT-Sn and MWCNT-SnNi,60
CNT-SnSb (produced by reductive precipitation),61 CNT-Sb,
and CNT-Bi (ball milled to introduce more defect sites into the
compound electrode structure)62 were tested to understand their
characteristics as anode of Li-ion batteries. Figure 6 presents a
comparison between these studies. Effect of the metal added in
the composite and current rate applied during charge-discharge
are quite evident from this figure. Higher current rate is found
to be detrimental to capacity and stability of the same electrode.
It may be noted from these studies that elements were selected
according to their theoretical capacities, as given in Figure 4.
The only element that was not chosen for this purpose is Pb,
probably due to its toxic effects. Although these initial studies
were promising enough to show benefits of using CNT-metal
composite electrodes, but expectations were much higher.
Application of Si particles with a carbonaceous material was
picked up during this period. A composite anode of silicongraphite-MWCNTs, prepared by ball milling, has shown an
initial discharge capacity of 2274 mAh/g and a reversible capacity (after 20 cycles) of 584 mAh/g.63 The reversible capacity
was much higher than that offered by MWCNT anodes or by
Si-graphite anodes, showing the beneficial effects of both Si
and MWCNTs in this composite electrode. Incorporation of
Si also elevates the capacity of the MWCNT-metal composite
anodes, as compared to similar composites using Sn/Sb/Bi/Ni
or their alloys. In a detailed study, Eom et al. showed that the
charge/discharge capacities of a MWCNT-Si composite anode
depend strongly on their weight ratio.64 The highest reversible
capacity and lowest irreversible capacity of the composite anode were offered by a 50:50 weight ratio and found to be
1770 mAh/g and 469 mAh/g, respectively. However, reversible
Downloaded by [Hanyang University] at 01:50 10 May 2013
138
I. LAHIRI AND W. CHOI
FIG. 6. Stability of CNT-Sn2 Sb composite electrode system: (a) at 40 mA/g (0–3.0 V for CNT electrode and 0–2.5 V for all other
electrodes) (reprinted with permission from Chen et al.58 Copyright 2002: Elsevier); (b) at 50 mA/g (0–2.0 V for all electrodes)
(reprinted with permission from Chen et al.59 Copyright 2003: Elsevier); (c) at 25 mA/g (0–1.5 V for all electrodes) (reprinted
with permission from NuLi et al.62 Copyright 2008: Elsevier); and (d) at 100 mA/g (0–2.0 V for all electrodes) (reprinted with
permission from Park et al.61 Copyright 2007: American Chemical Society). (Color figure available online.)
capacity was found to be degraded to 1200 mAh/g in 50 cycles.
In a similar study, Shu et al. found highest capacity of 1400
mAh/g, although capacity fading brought down the capacity to
950 mAh/g in 20 cycles.65 However, their results have shown
that better cyclability could be obtained using longer CNTs,
which are expected to provide better wrapping of Si particles
and more conductive network.
In a different approach, single-walled carbon nanotubes
(SWCNTs) were used along with graphite and Si powder, to
form a composite anode for Li-ion battery.66 The anode showed
a high reversible capacity of 900 mAh/g and a low rate of
capacity fading (0.3%/cycle) up to 30 cycles (Figure 7a) for
a nominal composition of 35 wt.% Si, 37 wt.% SWCNTs, and
27 wt.% graphite (balance 1 wt.% of residual carbon). Although
this composite anode has shown good capacity and low capacity fading rate, at least up to first 30 cycles, SWCNTs based
anodes did not generate much interest, due to its semiconducting nature which is expected to lead to slow kinetics issues. It
may be worthwhile to mention here that MWCNTs are considered to be metallic in nature and thus, are expected to offer
better rate capability, as compared to SWCNTs. Preference of
MWCNTs over SWCNTs and even double walled carbon nanotubes (DWCNTs) could firmly be concluded from the study
performed by Chew et al.67 They used three different types of
CNTs, i.e., SWCNTs, DWCNTs, and MWCNTs to prepare the
electrodes. MWCNTs performed better compared to other two
Downloaded by [Hanyang University] at 01:50 10 May 2013
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
139
FIG. 7. Si-SWCNT composite structure as anode of Li-ion batteries: (a) cyclability of Si-graphite-SWCNT anode (tested at
0.250 mA/cm2) (reprinted with permission from Wang and Kumta66 Copyright 2012: Elsevier); and (b) cyclability of the anode
prepared by incorporating porous Si film on SWCNT film, as compared with independent Si and SWCNT anodes (tested at 0.05
C in the 1st cycle and 0.1 C for rest 40 cycles) (reprinted with permission from Rong et al.71 Copyright 2010: American Chemical
Society). (Color figure available online.)
CNTs, in terms of much lower irreversible capacity loss, higher
and stable capacity for longer cycles, and ability to support up
to 10C rate.
Studies involving Si and MWCNT/SWCNTs have proven
capacity fading to remain as an important issue for all electrodes, incorporating Si in the micro-scale. Thus, the focus was
slowly shifting towards smaller scales and novel designs. In
the meantime, Si nanowire and Si nanotube anodes demonstrated exceptionally high capacity as anode of Li-ion batteries.34,68,69 Nanostructured Si was claimed to have avoided the
issue of pulverization. Detailed discussion about this topic is
beyond the scope of this article. However, exciting properties
of nanostructured Si immediately attracted attention for their
possible application in composite electrodes, along with other
novel structures. Among many such structures, a free-standing
MWCNT-Si film was promising for its unique structural features and properties. The structure contained a CNT network
which was infiltrated in the Si film to provide good conductivity, flexibility, and strength.70 The film itself could be used
as a current collector, thus, reducing weight of the battery. This
advantage placed this hybrid anode ahead of many other comparable structures, in terms of specific capacity and specific energy
density (Figure 8). An almost similar approach with porous Si
film with SWCNT film anode could achieve a specific capacity
of ∼2220 mAh/g, with 82% capacity retention in 40 cycles.71
A different technique of synthesizing CNT-Si composite was to
attach Si nano-particles with CNTs—either by grafting,72 or by
depositing droplets.73 Both the structures offered appreciably
high specific capacity for the anode, though the grafted anode
structure has seen a sudden fall in capacity after 35 cycles.
In another composite electrode, MWCNTs were coated onto
solution grown Si nanowires and the resulting electrode was
found to offer almost 5 times enhancement in specific capacity
of the electrode (after 75 cycles), as compared to the uncoated
anode.74 This huge enhancement can be attributed to good electrical conductivity and network connectivity, formed by the Si
nanowire-MWCNT composite. Contribution of MWCNT towards enhanced conductivity was further clarified by replacing acetylene black (AB)—normally used conductive additive,
by MWCNTs, in Si nanoparticles anode structure.75 The SiMWCNT anode showed twice the specific capacity of Si-AB
anode and was able to maintain a capacity of 900 mAh/g for
over 100 cycles.
Developments of CNT-metal anodes have shown good
promise, especially with nanostructured Si. MWCNTs are
preferred over SWCNTs, for anodic application in Li-ion batteries, owing to their metallic nature. MWCNTs can be used for
a variety of purposes, e.g., for Li-ion intake, as a conductive
additive and even as a current collector, replacing conventional
Cu or stainless steel current collectors. However, CNTs could
also be used as a composite electrode along with oxides and
polymers, which will be discussed in the following subsections.
4.2.1.2. CNT-oxide composite electrodes. Many metal
oxides are known as promising materials for application in Liion batteries.76 The most prominent one for such application
is tin oxide. In spite of the volume expansion problem during
lithiation (up to 200%), tin oxides were studied due to their high
theoretical specific capacity. However, different nanostructures
of tin oxides were proposed to avoid the pulverization. One
such novel structure is an ordered, nanostructured, tin-based
oxides/carbon composite (ONTC).77 This novel anode structure
was synthesized by depositing tin-based oxides (using SnCl2
and phosphorus ester as the precursors), into three-dimensional
nano-spaces of an ordered mesoporous carbon structure,
Downloaded by [Hanyang University] at 01:50 10 May 2013
140
I. LAHIRI AND W. CHOI
FIG. 8. Si-CNT novel designs and nanostructured composite anode for Li-ion batteries: (a) cyclability of free-standing Si-MWCNT
film anode; (b) and (c) advantages of free-standing Si-MWCNT film over other anodes, in terms of specific capacity and specific
energy density, (reprinted with permission from Cui et al.70 Copyright 2010: American Chemical Society); and (d) cyclability
of the anode structure consisting of nano Si droplets on vertically aligned MWCNTs (reprinted with permission from Wang and
Kumta73 Copyright 2010: American Chemical Society). (Color figure available online.)
CMK-3. This anode offered much higher and stable capacity,
as compared to other Sn-oxide based anodes. A much simpler
processing route for a CNT-Sn oxide anode structure can be infiltration of SnO2 nanoparticles inside MWCNTs.78 This composite anode showed a reversible capacity of 665 mAh/g after
the 1st cycle and 506 mAh/g after 40th cycles, registering a
0.6% capacity loss per cycle (Figure 9a). Although this structure seems to have sufficiently high rate of capacity loss, but it
offers much better stability as compared to nano-SnO2 anode
(offering a huge 2% loss per cycle). It may be noted here that
the structure contained SnO2 nanoparticles inside the tubular
spaces of MWCNTs. The walls of CNTs could restrict the volume change of Sn-oxide particles during lithiation/de-lithiation.
In contrast, the anode, having only SnO2 nanoparticles, faced
unrestricted volume expansion/contraction during lithiation/delithiation, leading to fast structural destruction and quick
capacity fading. On the other hand, an anode comprising of SnO2
nanocrystals deposited on the surface of MWCNTs showed a
lower capacity loss of 0.43%/cycle, for 100 cycles (Figure 9b),
although the reasoning of restricted expansion could not be
applied to this structure.79 The better stability in this case is
explained by the stronger bonding between CNTs and SnO2 ,
owing to higher pressure applied during solvothermal synthesis
of this composite anode structure. Rate capability of this anode was also found to be better than its individual components
in a wide range of 0.1–2.0 C rates. MWCNTs are expected to
maintain electron movement, especially at higher current rates,
leading to better rate capability of this anode.
Another CNT-SnO2 -based novel anode structure was proposed by Zhang et al.80 They have prepared a cross-stacked
CNT structure, in the form of a net, and attached SnO2 nanoparticles to this structure (Figures 9c and d). CNT network aided
in maintaining integrity of the structure. This anode delivered a
charging capacity over 850 mAh/g for at least 65 cycles, in a potential window of 0.01–3 V vs. Li+/Li. Binder-free structure of
this anode is another novelty with respect to most of other similar anode structures. The advantages of binder-free electrodes
will be discussed in detail in Section 4.2.2. Exciting properties
of this new anode structure, however, could be attributed to the
mesorporous structure helping in easy ion movement, continuous network of CNTs for better electron passage, support of
cross-stacked structure in holding the SnO2 nanoparticles, and
presence of high amount of SnO2 nanoparticles in the anode for
more Li+ ion insertion.
Downloaded by [Hanyang University] at 01:50 10 May 2013
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
141
FIG. 9. Performance of CNT-oxide composite anodes in Li-ion batteries: (a) cyclability of MWCNT-SnO2 nanoparticle (deposited
inside tubes) anode, as compared with other related structures (reprinted with permission from Fu et al.78 Copyright 2012: Elsevier);
(b) cyclability of SnO2 nanocrystal deposited on MWCNT surface (reprinted with permission from Du et al.79 Copyright 2012:
Elsevier); and (c) and (d) SEM images of cross-stacked CNTs, before (c) and after (d) SnO2 nanoparticle loading (reprinted with
permission from Zhang et al.80 Copyright 2009: John Wiley and Sons). (Color figure available online.)
MnO2 is another oxide material which offered, interesting
electrochemical properties as nanoscale structure, when used
along with CNTs. Reaction between MnO2 and Li can be expressed as:81
MnO2 + 4Li+ + 4e ↔ 2Li2 O + Mn.
[5]
Formation of Mn/Li2 O leads to a theoretical capacity of 1230
mAh/g for MnO2 .82 However, it was demonstrated by Xia et al.
that an initial specific capacity, higher than the theoretical capacity of MnO2 could be achieved through a caterpillar-like
nanoflaky MnO2 -CNT nanocomposites anode (Figure 10)(83)
The anode maintained a capacity of ∼800 mAh/g for first 20
cycles, although it dropped slowly to ∼600 mAh/g after 50
cycles. This composite anode performed better than individual
MnO2 anode. Rate capability of this novel anode structure was
also excellent, with appreciable capacities offered at very high
rates of 4000 mA/g. Enhanced electrochemical performance of
this electrode could be attributed to its unique three-dimensional
architecture, which could accommodate large volume changes
and enable faster ion and electron transport.
To overcome the issues related to stability and rate capability
of MnO2 , it was important to inhibit the causes, viz. high over
potential, low conductivity, and high stress/strain during repeated lithiation/de-lithiation process. A novel amorphous
MnOx –C nano-composite with inter-dispersed carbon was reported to address these issues, at least partly.84 In this structure,
carbon, with its high conductivity, promote rate capability. Carbon also filled pores of the amorphous MnOx , which prevented
flow of electrolyte and reduced solid electrolyte interphase (SEI)
formation. This helps to lower irreversible capacity loss of the
anode. Further, amorphous structure of MnOx reduced the pulverization. Aided by such benefits, this novel structure led to
attainment of a capacity of ∼600 mAh/g, for almost 140 cycles
with an excellent rate capability.
Downloaded by [Hanyang University] at 01:50 10 May 2013
142
I. LAHIRI AND W. CHOI
FIG. 10. Novel architectures/morphologies of CNT-based electrodes in Li-ion batteries: (a) MnO2 on CNT coaxial hybrid electrode
(reprinted with permission from Reddy et al.168 Copyright 2009: American Chemical Society); (b) flower-like three-dimensional
CuO-CNT nanomicrosphere structure (reprinted with permission from Zheng et al.85 Copyright 2008: American Chemical Society);
and (c) MnO2 nanoflowers onto CNT-enabled conductive textile fiber electrode (reprinted with permission from Arie et al.206
Copyright 2011: American Chemical Society).
CuO-CNT composite anodes have also attracted some attention, due to their promising properties and, especially, for
their exciting architectures. A CuO-CNT flower-like structure,
named as nanomicrospheres, has shown very stable capacity
of 500 mAh/g for at least 25 cycles (at 0.1C rate) and a
promising behavior at higher rate operations, offering appreciable capacities up to 5C rate.85 Both CNTs and CuO were
responsible for providing Li-ion capacity in this composite anode, while CNT was important for maintaining a conductive
path. Another design of CuO-CNT composite anode contained
a sandwiched structure of Cu-CuO-SWCNT mat.86 The hybrid anode was formed in situ during synthesis of SWCNT
macro-film formation on Cu foils. Rate capability of this 3component hybrid electrode is highly interesting, as it offers
517 mAh/g at 0.2C, 418 mAh/g at 5.0C, and 223 mAh/g at
50C. Excellent capacity retention by this anode at high current rate, could be correlated with change in the electronic
properties of both Cu-oxide and SWCNT during lithiation and
de-lithiation.
Among other oxides, CeO2 and MoO2 were used to prepare
composites with CNTs and applied as an electrode of Li-ion
batteries. However, CeO2 -CNT composites, prepared as CeO2
nanoparticles attached to CNTs by a hydrothermal treatment,
failed to show any promise.87 This composite anode offered
lower capacity than CNT anodes and thus could not generate any
further interest. On the other hand, MoO2 -C hybrid nanowire
anode has shown good promise for electrode applications in
Li-ion battery.88 This novel anode structure offered a capacity
of ∼350 mAh/g, at high current rate of 1000 mA/g. However,
detailed understanding of the charge transfer mechanism in this
hybrid electrode is required before its possible applications in
Li-ion battery.
Although a variety of CNT-oxide composite electrodes were
studied, very few were able to show good promise for practical
applications. CNT-SnO2 is one of the main composite structures which need to be studied more for future developments.
Owing to high theoretical capacity of Sn-oxide, this novel composite could be able to generate exciting properties suitable for
next-generation Li-ion batteries, provided issues related to volume expansion and pulverization would be taken care of. New
morphologies are being proposed for addressing the issue of
capacity fading,89 although further research is needed. Future
development might also need designing new architectures.
MnO2 -CNT and CuO-CNT also have shown good promise, especially, high rate properties of CuO-CNT composite anode
were really exciting. However, more detailed studies into these
systems are required for considering these composite electrodes
in actual industrial applications.
4.2.1.3. CNT-Polymer Composite Electrodes. CNTpolymer composites were in focus only recently and its importance is increasing with the demand of flexible batteries to
be used in flexible consumer electronic devices. Among the
polymers, polyaniline (PANi) is considered as the most important conducting polymer for possible applications in energy
storage, owing to its high electrical conductivity, thermal and
chemical stability, interesting red-ox properties, easy processing techniques and low cost. In an initial effort by Sivakkumar
et al., a CNT-PANi composite was prepared by in situ chemical polymerization of aniline in well-dispersed CNT solution
and the resulting composite electrode was used as an electrode
in Li-ion battery.90 A half-cell, using this composite as cathode and Li metal as working and reference electrode, have
offered 86 mAh/g capacity after 80th cycle, with an average
coulombic efficiency of 98%. Although the properties were not
really exciting, but such a study opened a new way of flexible,
all-solid-state batteries. Recently, a layer-by-layer assembled
PANi nanofiber-MWCNT thin film electrode has shown considerable progress, in terms of high volumetric capacity (∼210
Downloaded by [Hanyang University] at 01:50 10 May 2013
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
143
FIG. 11. Advantages of the interface-controlled, directly grown MWCNTs on Cu current collector anode system for Li-ion
batteries. Schematics of (a) Lithiation/de-lithiation mechanism, showing high amount Li-ion insertion and (b) advantages of the
anode structure. (Reprinted with permission from Lahiri et al.101 Copyright 2010: American Chemical Society.) (Color figure
available online.)
mAh/cm3) as cathode of a lithium battery.91 Further, similar
approaches to combine CNTs, oxides and polymers were undertaken in an effort to simplify the battery architecture, either
combining a solid electrolyte with the electrode92 or attaching
a separator with it93 or integrating the electrode, separator, and
electrolyte together in single nanocomposites structure.94 These
novel designs are helpful to reduce total battery weight. All
such applications open a new area of lithium-polymer batteries
and needs to be understood separately. Since, lithium-polymer
batteries are kept beyond the scope of this article, further discussion on this issue will not be included here. Readers are
referred to the cited published articles and/or all other suitable
references.
4.2.2. Binder-free CNT-based Electrodes
As pointed out in the initial part of Section 4.2, preliminary
studies involving CNTs in electrode applications of Li-ion battery was dominated by usage of individual CNTs only. Following failure of the early CNT-based electrodes, idea of preparing
composite CNT-based electrodes, either with another metal or
oxide was developed. It may be pointed out easily from Table 1
that most of the electrodes, studied so far, included a current carrier material (mostly, carbon black, CB) and a binder material
(mainly, polyvinylidene fluoride, PVDF). Neither of these materials contributes to Li-ion insertion and, hence, considered as
redundant weight for a typical Li-ion battery. Moreover, PVDF
reacts with graphitic materials and metallic lithium to form stable compounds.95–98 These reactions are often exothermic; e.g.
reaction with metallic Li produces 7.2 kJ per gram of PVDF
used.95 Hence, presence of PVDF as binder could lead to thermal runaway of the battery. Demands for reducing the weight
of Li-ion batteries and incorporation of better safety features
have led to the development of binder-free electrodes. Due to
the uniqueness of structure, this type of electrode needs separate
discussion.
In order to address all these issues, the present authors have
developed an anode for Li-ion battery, involving direct synthesis
of interface-controlled MWCNTs on copper current collectors.
This kind of structure is expected to have many advantages over
the conventional anodes (Figure 11). Firstly, unlike past studies,
directly grown CNTs on current collector avoids the polymeric
binders completely. This avoids harmful effect of the polymeric
binder (exothermic reaction), reduces weight of the electrode,
increases specific capacity, and shows potential to be used for
high temperature application. Secondly, direct growth of CNTs
on a Ti/Ni interlayered Cu substrate ensures that each CNT is
well bonded to the current collector99,100 and thus all of them
contribute to the capacity. Third, high specific surface area of
CNTs allows more Li-ion intercalation leading to more capacity.
Fourth, high electrical conductivity and excellent long-term stability, which are already known from past researches, promote
MWCNTs to be an ideal candidate for Li-ion batteries. Moreover, by the interface-control, proposed in this study, ohmic
contact and strong bonding between the CNTs and substrate are
ensured, which further helps in efficient charge transport. Further, the synthesis process involves a simple two-step (catalyst
deposition and chemical vapor deposition) technique, which is
easy for scaling-up to industrial level.
This interface-controlled, directly-grown MWCNTs-on-Cucurrent-collector anode structure has offered excellent electrochemical properties.101 The first lithiation cycle, at a current
rate of 38 mA/g, showed very high capacity (>2500 mAhg−1),
followed by an irreversible capacity loss of 42%, to offer a capacity of 1455 mAhg−1 after first de-lithiation. In spite of this
big fall, reversible capacity was almost maintained from the
second cycle onward (Figure 12). The anode offered very good
rate capability as well. Even at a high current rate of 1.116 A/g,
Downloaded by [Hanyang University] at 01:50 10 May 2013
144
I. LAHIRI AND W. CHOI
FIG. 12. Electrochemical properties of the interface-controlled, directly grown MWCNTs on Cu current collector anode system
for Li-ion batteries. (a) Rate capability of the anode at different current rates and (b) stability and Coulombic efficiency of the
anode structure. (Reprinted with permission Lahiri et al.101 Copyright 2010: American Chemical Society.)
the anode showed a reversible capacity of 767 mAh/g, which
is 106% increment in capacity as compared to theoretical capacity of graphite (Figure 12a). This novel anode structure also
demonstrated excellent stability—900 mAh/g (140% more as
compared to theoretical capacity of graphite) at a current rate
of 372 mA/g and nil capacity degradation during 50 cycles (except for the initial two cycles). The coulombic efficiency of the
electrode also remained very high (> 99%), after two initial
cycles (Figure 12b). Such high capacity and nil capacity degradation over 50 cycles make this electrode a suitable alternative
to graphite anodes.
In an attempt to enhance capacity and safety of the structure,
MWCNTs of this anode was further given an ultra-thin alumina (Al2 O3 ) coating, by atomic layer deposition technique.102
This structure has shown increase in specific capacity of the
electrode, owing to extra Li-ion insertion sites provided by the
alumina coating. The anode offered a higher specific capacity
∼1100 mAh/g, for 50 cycles, with a low capacity fading rate of
0.1% per cycle. Rate capability of this anode is excellent—an
increase in current rate from 112 mA/g to 1116 mA/g lead to a
comparatively lower drop in capacity, from 1180 mAh/g to 1080
mAh/g. This excellent rate capability makes this anode suitable
for applications requiring higher charging rates. Further studies
are undergoing to understand the charge transfer mechanism in
both the CNT-based and alumina-coated CNT anodes.
It is worth mentioning here that many other similar studies
to develop binder-free anode structures for Li-ion battery were
reported. In one such study, flexible free-standing carbon nanotube films were prepared by mixing CNTs with 10 wt% carbon black, dispersed into a surfactant, ultrasonically agitated,
filtered through a porous PVDF film, cleaned and washed, and
finally, peeled off from the PVDF membrane to obtain a flexible, binder-free CNT anode.67 This study was repeated for three
different types of CNTs viz. SWCNTs, DWCNTs, and MWCNTs. It was reported that MWCNTs were much better choice as
Li-ion battery anode, compared to other two varieties of CNTs.
Downloaded by [Hanyang University] at 01:50 10 May 2013
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
145
FIG. 13. Electrochemical properties of the ultrathin alumina coated MWCNTs on Cu current collector anode system for Li-ion
batteries: (a) rate capability of the anode at different current rates and (b) stability of the anode structure. (Reprinted with permission
from Lahiri et al.102 Copyright 2011: Royal Society of Chemistry.) (Color figure available online.)
Similar attempt to produce flexible electrodes using aligned
CNTs, however, did not show any appreciable property as anode of Li-ion batteries.103 Binder-free CNT-based electrodes (on
stainless steel foil) have also been proposed by Masarapu et al.,
but the specific capacity of the anode was not very high.104
On the other hand, when such aligned CNTs were supported at
their base with thin Ni film, specific capacities in the range of
800–850 mAh/g, at 50 mA/g rate, could be obtained.105 Ti was
predicted as a better contact material for SWCNT film anode,
than Ni.106 A quick comparison between these studies identifies
the importance of incorporating a strong and conducting support to the CNT-based electrodes. Moreover, length of CNTs
and their alignment were reported to have notable effects on
electrochemical properties of the anodes.107
Another way to prepare a high-power, CNT-based, additivefree electrode for Li-ion battery could be application of layer-bylayer technique to assemble densely packed and functionalized
CNTs as electrode.108 Such an electrode exhibited high gravimetric energy (200 Wh/kg) at a very high power of 100 kW/kg,
considering weight of the single electrode only. High energy and
power capabilities of this anode structure could be attributed to
the surface oxygen containing functional groups attached to the
MWCNTs. Further, different chemicals can be added to electrolytes in order to enhance capacity of batteries, containing
binder-free electrode.109 However, such developments are beyond the scope of this article.
Several techniques are available for preparing binder-free,
CNT-based electrodes for Li-ion batteries. Comparison of all
such techniques shows that strong bonding between MWCNTs
and current collector material is highly important. Hence, directgrowth of MWCNTs on Cu current collector seems promising.
Further, proper functionalization of the CNTs can improve on its
energy and power capacities. In the near future, such binder-free
electrodes are going to be important for safer and lighter bat-
teries. Additional functionality of flexibility of the battery can
potentially extend its application regime to next-generation electronic devices. Novel morphologies, e.g., quadrangular CNTs
(q-CNT),110 need to be studied in detail for better understanding of their prospects.
4.3. Two-Dimensional Carbon: Graphene and its
Composites
Graphene is being projected as a material with many exciting properties. Simple processing technique to prepare this twodimensional material, as proposed by Geim and Novoselov, has
revolutionized research efforts in graphene. Figure 1b clearly
indicates that research involving graphene, for possible application in Li-ion batteries, has been accelerated in last few years.
Graphene has been experimented extensively for application
as an anode material in Li-ion batteries, replacing conventionally used graphite. Graphene’s unique two-dimensional structure renders itself a specific advantage of attaching Li-ions on
both surfaces of the hexagonal C-ring based sheet. Thus, it is
expected that graphene will show much more Li-ion insertion
capacity, as compared to its bulk counterpart, graphite. Structural similarities between graphene and graphite also created
much interest in this structure. Graphene was used either individually or as a composite with other candidate materials, for
anodic application in Li-ion batteries.
4.3.1. Graphene Electrodes
Graphene nanosheets (GNS) were the first material in this
category to be tested for anodic application of Li-ion battery.111
This material could be prepared by exfoliating a bulk graphite
crystal to make a dispersion of individual graphene sheets, and
then reassembling them to form the layered GNS structure. GNS
Downloaded by [Hanyang University] at 01:50 10 May 2013
146
I. LAHIRI AND W. CHOI
FIG. 14. Structure and electrochemical properties of graphene nanosheet (GNS)-based anode for Li-ion batteries: (a) TEM image
of the GNS structure; inset presents cross-sectional TEM image to show number of layers and (b) stability of the anode structures
consisting of (i) graphite, (ii) GNS, (iii) GNS + CNT, and (iv) GNS + C60 . (Reprinted with permission from Yoo et al.111 Copyright
2008: American Chemical Society.) (Color figure available online.)
had multiple layers of graphene sheets. Initial charge capacity
of this anode material was found to be ∼540 mAh/g, which
is much higher than the conventional graphite anode material
(Figure 14a). However, in 20 cycles, the capacity faded down to
∼300 mAh/g level (Figure 14b). Li-intercalation capacity was
found to be dependent on the interlayer distance. Increasing this
interlayer distance, by addition of other active agents like CNTs
and C60 molecules, was observed to be beneficial for increasing
capacity of the electrode. These structural modifications will be
further discussed in the next Section 4.4 of nanostructured C-C
composites.
Graphene nanoribbon (GNR) is another structural variety
which can be used for electrode applications for Li-ion batteries. GNR structure, produced by a solution based oxidative
technique to un-zip MWCNTs followed by a reduction step,
has shown minimal improvement in capacity over conventional
graphite anodes.112 On the other hand, oxidative GNR (ox-GNR)
has shown much better performance with reversible capacities
in the range of 800 mAh/g. Presence of high amount of hydrogen
and oxygen atoms on the ox-GNRs surface probably has triggered more Li-ion intake. This development immediately points
out towards the possibility of doped or functionalized graphene
structures for anodic applications. An N-doped graphene, synthesized directly on a Cu foil through a liquid precursor based
CVD method, was reported to offer almost double the reversible
capacity as compared to pristine graphene anode (Figure 15).113
Enhanced capacity of the N-doped graphene anode was related
to large number of defect sites created by N-doping, which
elevated Li-ion insertion ability of the structure. Similar observation has been reported by Wang et al. on N-doped GNS, which
was prepared by high temperature treatment of graphite oxide
in an ammonia atmosphere.114 N-doped and B-doped graphene
anodes, prepared through oxidation and thermal exfoliation of
natural flaky graphite powder, were also found to offer excellent specific capacity and rate capability.115 These samples
have shown specific capacities of 199 and 235 mAh/g, respectively, even at a very high current rate of 25 A/g. Such exciting
properties of doped graphene structures can be attributed to
many factors, namely, their unique two-dimensional structure,
disordered surface, heteroatomic defects, improved wettability between the electrode and electrolyte, increased inter-layer
spacing, higher electrical conductivity, and thermal stability.
While disordered structure, heteroatomic defects, and doping
(such as N-doping) introduces more defect sites for additional
lithiation, factors like wettability and high thermal and electrical
conductivity contribute directly to improve structural stability
and kinetics of charge transfer. All these features ensured rapid
absorption of large amount of Li+ ions on the anode surface
and ultrafast diffusion of ions and electron transport, leading to
excellent specific capacity and rate capability. Another noteworthy feature for N-doped graphene anodes is the predominance
of pyridinic type of N-atoms over pyrrolic and graphitic types.
Pyridinic type of N-atoms is known to show better Li-ion reversible capacity, compared to its other varieties.116 Thus, ensuring presence of maximum amount of pyridinic N-atoms could
be a factor in attaining high capacity from N-doped graphene
electrodes.
Apart from these doped graphene structures, reduced
graphene sheets with some amount of residual oxygen were also
predicted for possible application as electrode in Li-ion batteries.117 Benefits from such doped/functionalized graphene electrodes can further be enhanced by incorporation of hierarchical
Downloaded by [Hanyang University] at 01:50 10 May 2013
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
147
FIG. 15. Electrochemical performance of N-doped graphene directly grown on Cu foil: (a) stability of N-doped and pristine
graphene electrodes and (b) rate capability of the N-doped graphene. (Reprinted with permission from Reddy et al.113 Copyright
2010: American Chemical Society.) (Color figure available online.)
architecture into the electrode design. A bio-inspired honeycomb type structure of reduced graphene oxide (RGO) could
offer high specific capacity of 1150 mAh/g after 50 cycles (at
a current rate of 50 mA/g), demonstrating the importance of
creating novel device architectures.118 Another novel graphene
based electrode structure could be holey graphene—a graphene
electrode having in-plane porosities in it, created by wet chemical technique.119 Such a structure could offer numerous sites for
ionic binding, high ion transport rate, and thus, a very high rate
capability, comparable to that offered by supercapacitors.
One important observation noted from these studies is the
variability in the graphene structure and morphology. Different
synthesis techniques have been approached, resulting in formation of diverse structural features. Thus, it seems important to
study the effect of specific structural features of graphene on
their electrochemical responses. Number of layers is an important structural parameter for graphene. It was observed that few
layer graphene (FLG) could interact with Li+ ions in a manner
very similar to its bulk counterpart, graphite.120 However, single
layer graphene (SLG) showed very poor interaction with Li+
ions, with only 5% of surface coverage. Such behavior could be
related to strong Coulombic repulsion between Li+ ions on opposite surfaces of graphene sheet. Thus, it seems, for all practical
purposes, multiple-layered graphene could be a better material
for Li-ion batteries. Contrary to this observation, SLGs were
estimated to have higher charge rate constants than its multilayered counterparts, leading to an apprehension that SLGs could
offer better kinetics.121 Edge structure of graphene is another
significant feature, which was simulated to understand Li diffusion through different types of edges.122 Edges were predicted to
have much lower energy barrier to Li-ion diffusion, compared to
bulk of the graphene structure. Thus, graphene structure having
narrow ribbons (having more number of edges) is expected to
show better lithiation capacity. However, more number of active
sites will lead to formation of more SEI and hence, could lead
to higher irreversible capacity. Thus, it is important to verify
the actual properties of such graphene structures experimentally. Diffusion of Li has a preferential path inside the graphene
sheet. It was predicted through simulation that diffusion of Li
atom should be favorable along the C-C bond axis, compared to
that via midpoint of C-C bonds.123 Although these theoretical
studies were helpful in predicting internal mechanism of Li-ion
interaction with graphene, experimental verification of these
issues are necessary to gain more knowledge on these issues.
4.3.2. Graphene-Metal Oxide Composite Electrodes
Graphene has been extensively studied as a composite with
other materials, mostly oxides, for application in Li-ion batteries. Among different oxides, Sn-oxide, owing to its high theoretical capacity, was the most frequent choice for making these
composites. A novel design of SnO2 -graphene nanoporous electrode has demonstrated much higher and more stable capacity,
as compared to its individual components.124 Enhanced properties of this electrode could be related to its unique design, in
which SnO2 nanoparticles were confined by GNS to limit volume expansion problem, while the nanopores formed between
the nanoparticles and GNS provided space for ionic movement.
These structural advantages allowed the anode to show 810
mAh/g capacity after second cycle and to retain the capacity up
to 570 mAh/g after 30 cycles. While SnO2 nanoparticles showed
rapid decay in capacity in just 15 cycles, capacity of graphite and
graphene always remained lower than that of SnO2 -graphene
electrode. Inspired by the success of this anode, different other
structural/design varieties of SnO2 -graphene have been studied
Downloaded by [Hanyang University] at 01:50 10 May 2013
148
I. LAHIRI AND W. CHOI
FIG. 16. Structure and electrochemical performance of SnO2 -graphene nanoporous electrode: (a) stability of (i) SnO2 nano
particles, (ii) graphite, (iii) GNS, and (iv) SnO2 -GNS nanoporous electrode; and (b) SEM image of the SnO2 -GNS nanoporous
structure. (Reprinted with permission from Paek et al.124 Copyright 2009: American Chemical Society.)
as anode of Li-ion batteries. In one such structural variation,
nearly mono-dispersed SnO2 nanoparticles were loaded on both
sides of a single layer graphene structure, with high (60 wt.%)
loading content of SnO2 .125 This anode offered a first cycle
reversible capacity of 786 mAh/g and was able to retain 558
mAh/g capacity after 50 cycles. While higher capacity of this
anode could be correlated to higher loading amount of SnO2
nanoparticles, better cyclability could be due to ability to re-
duce pulverization of SnO2 nanoparticles by strong attachment
between the nanoparticles and graphene sheet, and elastic nature of the graphene sheet. A classic example of a new design
of SnO2 -graphene composite electrode is the self-assembled,
layered SnO2 -graphene film (Figure 17).126 This novel design
consists of alternate layers of SnO2 nanoparticles and graphene,
synthesized through a self-assembly technique. Such a design ensures that the anode could accommodate sufficiently
FIG. 17. Self-assembled layered structure of SnO2 -graphene electrode: (a) schematic of the structure showing layer-by-layer
stacking graphene and SnO2 nanoparticles and (b) stability (top) and rate capability (bottom) of this anode structure. (Reprinted
with permission from Wang et al.126 Copyright 2010: American Chemical Society.) (Color figure available online.)
Downloaded by [Hanyang University] at 01:50 10 May 2013
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
high loading amount of SnO2 and still maintain its electrical
paths through graphene. Furthermore, alternate graphene layers
incorporate enough flexibility to accommodate volume expansion strains of SnO2 nanoparticles. These benefits lead to a high
(∼600 mAh/g) and stable capacity of the anode structure for
more than 100 cycles. In another very recent study, closely related SnO2 -graphene layered composite has been prepared by
depositing SnO2 onto graphene through ALD process.127 Depending upon the ALD process parameters, SnO2 could either
be crystalline or amorphous. Although both amorphous and
crystalline SnO2 -graphene layered composite has shown good
capacities, it was observed that amorphous structure was better
than the crystalline one, in terms of offering higher capacity
and better stability. This observation could be related to intrinsic isotropic nature of the amorphous SnO2 , which controlled
large volume changes of SnO2 during lithiation/de-lithiation.
Amorphous SnO2 -graphene composite has demonstrated a reversible capacity of 793 mAh/g, after 150 cycles. Thus, SnO2 graphene composite appears to be a potential electrode material
for next-generation Li-ion batteries. A proper combination of
morphology and design could promote this composite as a possible replacement of conventional graphite anodes.
Apart from SnO2 , another oxide material which has generated some interest as graphene-oxide composite anode structure
for Li-ion battery is Cu-oxide, although initial studies for this
type composite electrode was not encouraging.128 A grapheneCu2 O nanocube composite, synthesized through a chemical processing route, was proposed by Xu et al. for application as anode in Li-ion battery. Cu2 O nanocubes were attached to the
graphene sheets and dispersed randomly throughout the structure. This composite anode has offered an initial capacity of
∼1100 mAh/g, but it showed very high capacity fading rate to
have ∼300 mAh/g, after only 30 cycles. Although the authors
did not explain any possible reason for poor cyclability of this
composite anode structure, probably cubic morphology of the
nanoparticles is the reason for failure of this structure. Cubic
shape is not the best structure for achieving surface area enhancement. A change in morphology of the nanoparticles could
probably improve the situation, which was demonstrated later.
A self-assembled anode structure of graphene-CuO nanocomposites, consisting of a three-dimensional graphene network and
urchin-like CuO nanostructure, has offered interesting electrochemical properties.129 Even up to 100 cycles, the electrode
delivered a reversible capacity of 600 mAh/g, tested at a current rate of 65 mA/g. Rate capability of the anode was also
excellent—it showed 150 mAh/g capacity at a high current rate
of 6400 mA/g. Exceptional performance of this composite anode could be related to three-dimensional conductive network of
graphene and unique, high-surface-area nanostructure of CuO
particles. Another interesting structure is assembly of alternate
layers of CuO nanosheet and GNS, which was also reported to
offer substantially higher Li-ion storage capacity of 900 mAh/g,
after 40 cycles and 650 mAh/g, after 100 cycles.130 However,
as is evident from the properties, the anode had a substantially
149
high capacity fading rate. Thus, new structure and design of
CuO-graphene composite is needed to demonstrate attracting
properties for anodic application of Li-ion batteries.
Fe-oxide/graphene composites have also shown some
promise as electrode in Li-ion batteries. Recognizing that Fe-O
system exists in various stoichiometric ratios, it is important
to know which structure will be beneficial for Li-ion storage
purpose. Reactions of different Fe-oxides with Li-ion can be
viewed as follows:
FeO + 2Li+ + 2e ↔ Fe + Li2 O
Fe2 O3 + 6Li+ + 6e ↔ 2Fe + 3Li2 O
[6]
[7]
Fe3 O4 + 8Li+ + 8e ↔ 3Fe + 4Li2 O.
[8]
Equations (6)–(8) clearly show that capacity of reacting with
more Li+ ions increases in the order of FeO, Fe2 O3 , and Fe3 O4 .
While one Fe3 O4 molecule can react with 8 Li+ ions, Fe2 O3
reacts with 6 Li+ ions and FeO with only 2 Li+ ions. Thus,
it is expected that Fe3 O4 will have much more Li storage capacity than the other two compositions. However, theoretical
specific capacities of Fe2 O3 and Fe3 O4 are 1007 mAh/g and
926 mAh/g, respectively. Great promise of Fe-oxides has attracted researchers to investigate the electrochemical properties
of these oxides in Li-ion battery system and few research efforts
were reported in 2011. While Ji et al.131 and Su et al.132 proposed very similar processes to synthesize an electrode structure
consisting of Fe3 O4 nanoparticles, homogeneously distributed
on RGO nanosheets, Zhu et al.133 worked with Fe2 O3 nanoparticles decorated on RGO nanoplatelets. These studies revealed
that nanostructured Fe-oxides, be it Fe2 O3 or Fe3 O4 , could offer
good rate capability in a composite anode with graphene (Figure 18). Structural investigations revealed formation of strong
covalent bonds (Fe-O-C bond) between graphene basal planes
and Fe-oxide nanoparticles,134 which is probably the driving
force for good stability and rate capability for this hybrid anode.
As expected from theoretical specific capacities of these two
oxides, Fe2 O3 offered little higher capacities at higher current
rates, as compared to Fe3 O4 . For both these composites, performances of their individual components were much worse,
thus proving the importance of applying composite materials as
electrodes in Li-ion battery applications.
Many other graphene-based composite electrodes, using
metal oxides, have been tested for their possible application
as anode in Li-ion batteries. Metal oxides include TiO2 ,135
V2 O5 ,136 Mn3 O4 ,137 Co3 O4 ,138,139 Li4 Ti5 O12 .140 Among these
graphene-metal oxide composite anodes, graphene-Co3 O4 composite, especially the sheet-on-sheet structure,138 shows immense promise. However, most of these researches are in their
nascent stage and needs further study before being able to predict about their future. A very recently published article has
presented a thorough overview of the graphene-metal oxide
composites in Li-ion battery applications, which may be referred for detailed information on this type of specific composite
structures.141
Downloaded by [Hanyang University] at 01:50 10 May 2013
150
I. LAHIRI AND W. CHOI
FIG. 18. Comparison of electrochemical performance of Fe-oxide/graphene electrodes for Li-ion battery. Rate capability of (a)
Fe3 O4 nanoparticle-RGO anode (reprinted with permission from Su et al.132 Copyright 2011: American Chemical Society) and
(b) Fe2 O3 nanoparticle-RGO anode (reprinted with permission from Zhu et al.133 Copyright 2011: American Chemical Society).
(Color figure available online.)
4.3.3. Other Composite Electrodes with Graphene
Apart from graphene-oxide composite structures, another
material which appears to be promising as a composite anode for Li-ion battery is MoS2 . This material has a layered
structure—very much similar to graphene—and the layers are
held together by weak van der Waals forces. Such a structure
allows enormous space for Li-ion storage and an easy diffusion
path. As a result, a graphene-MoS2 composite is expected to
offer exciting properties as anode of Li-ion batteries. A MoS2 graphene-poly ethylene oxide (PEO) composite anode (weight
ratios of 93:2:5), prepared by hydrolysis of lithiated MoS2 in an
aqueous solution of PEO and graphene, has shown exceptional
properties, especially at very high rates.142 At an extremely
high rate of 10,000 mA/g, the electrode delivered a specific
capacity of ∼250 mAh/g and returned back to ∼600 mAh/g
capacity level at 50 mA/g current level. The same composite without graphene failed to offer any capacity at such high
rate, clearly demonstrating the beneficial effects of adding a
small amount of graphene in the composite anode. If graphene
is replaced by amorphous carbon in a composite anode with
MoS2 , specific capacity of the anode remains highly stable
for almost 100 cycles, although rate capability is yet to be
checked.143 These studies indicate the potential of graphene
for possible application in next generation Li-ion battery
electrodes.
Graphene-based composite anodes have also included elements as the second phase in the structure. A functionalized
graphene sheet-sulfur nanoparticle hybrid anode structure was
able to offer a specific capacity of ∼500 mAh/g (equivalent to
460 mAh/cm3) at a high current density of 1680 mA/g, with
almost 75% capacity retention ability in 100 cycles.144 Such an
electrode structure looks promising for next generation lithiumsulfur batteries.
This section presented an overview of graphene and
graphene-based composite structures for possible application as
anode in Li-ion batteries. Presence of graphene was found to enhance electrochemical properties of the electrodes by a substantial margin. Many novel composites and new architectures have
been proposed; many of them have demonstrated good promise
for future applications. Even graphene was reported to boost the
performance Li-ion batteries, when it was used in a very small
quantity, as a replacement of commercial carbon-based additives.145 Thus, the future of graphene-based electrodes appears
bright and detailed studies on promising compositions/designs
may bring out a true replacement of graphite for future Li-ion
batteries.
4.4. Nanostructured C-C Composites
CNTs and graphene have shown enormous scope for application in Li-ion batteries as electrode material—either individually
or as a composite with other elements (e.g., Si) or oxides (e.g.,
SnO2 ). Successes of these materials have led to development
of a C-C type composite, involving two or more varieties of C
polymorphs. This section will overview different types of C-C
nanostructured composites.
CNT/nano-honeycomb-diamond (CNT-NANO) composite
electrode was fabricated by Honda et al. through introduction
of MWCNTs into the pores of nano-honeycomb diamond.146
This is probably the first application C-C nanocomposites in
Downloaded by [Hanyang University] at 01:50 10 May 2013
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
151
FIG. 19. Various types of C-C nanocomposite electrodes for Li-ion battery: (a) CNF@CNTs composite anode—a schematic of
synthesis process and (b) its cycle behavior (reprinted with permission from Zhang et al.147 Copyright 2012: John Wiley and
Sons); (c) schematic of growing CNFs on graphene sheets and (d) stability of GNS-CNF composite anode as Li-ion battery anode
(reprinted with permission from Fan et al.152 Copyright 2011: American Chemical Society). (Color figure available online.)
Li-ion battery. While the samples with high CNT density were
found to be suitable for Li-ion battery application, the lowdensity structure was more suitable for a supercapacitor, as it
showed electrochemical double-layer discharging on diamond
surfaces. As Li-ion battery electrode, this hybrid structure offered a specific capacity of 894 mAh/g. However, diamond
being electrically insulated, is not expected to show any appreciable level of electron kinetics and, thus, its application in
Li-ion battery is really limited. Understanding this limitation,
the focus of C-C nanocomposites was quickly shifted to other
possible combinations. One such structure is carbon nanotube
encapsulated carbon nanofibers (CNFs@CNTs),147 which was
synthesized by selective deposition of Co on inside walls of
CNTs (through a capillary force-based incipient wetness impregnation method), followed by CNF growth by catalytic
chemical vapor deposition process. Performance of this hybrid
anode was better than its individual components, i.e., CNTs and
CNFs and it delivered a stable capacity of 410 mAh/g (at C/5
rate) for 120 cycles. In a little different variation of the anode
structure, CNTs were grown on a carbon fiber paper (main-
taining its highly porous nature) and was used directly as an
anode.148 Such a flexible anode could show a stable reversible
capacity of ∼550 mAh/g for 50 cycles. CNTs can also be added
with a mesoporous carbon material in order to develop an interesting anode structure, which has shown exceptionally high
rate capability.149 Such an electrode offered 94 mAh/g capacity at a very high rate of 30C, which appears to be promising
for fast-charging needs in Li-ion batteries. Excellent properties
of this hybrid anode can be interpreted as a synergistic effect
of MWCNTs and mesorporous carbon, in terms of high electronic conductivity of MWCNTs and fast charge transfer kinetics offered by nm-thick pore walls of the mesorporous carbon
structure.
Recent thrust in C-C nanocomposites for Li-ion battery is
on application of graphene, owing to its high electrical conductivity and high available surface area for lithiation. Initial effort was limited to increase the inter-layer spacing of graphene
by application of macromolecules like CNTs and fullerene
(Figure 14).111 Compared to GNS-based anode, these CNT or
C60 modified anodes have shown substantial improvement in
Downloaded by [Hanyang University] at 01:50 10 May 2013
152
I. LAHIRI AND W. CHOI
reversible capacity (Table 1), although stability remained an issue. Insertion of CNTs and fullerene molecules expanded the
interlayer spacing making it an actually three-dimensional structure with much higher number of lithiation sites, which led to
achievement of high capacity in CNT/fullerene modified GNS
anodes. In a rather recent development, vertically aligned CNTs
were grown directly on graphene and the hybrid structure could
be characterized by stable capacity and good rate capability.150
A reversible capacity of 55 mAh/g was achieved at a high current
rate of 3600 mA/g. However, overall capacity of this electrode
was not very high. A very similar structure, containing in situ
grown CNTs on GNS, have shown much better properties as
Li-ion battery anode.151 This composite anode displayed high
reversible capacity of 573 mAh/g at 0.2C rate and 520 mAh/g at
2.0C rate. This extra-ordinary rate capability can be linked with
the fast charge transfer kinetics through the CNT-graphene network. A very similar structure is CNFs grown on GNS, as proposed by Fan et al.152 This composite anode also demonstrated
good capacity and stability, along with excellent rate capability.
A stable reversible capacity of 667 mAh/g was achieved for
30 cycles, at a current rate of 0.12 mA/cm2. The electrode was
able to offer ∼190 mAh/g capacity at a very high current rate
of 6 mA/cm2, which is equivalent to 10C rate. A quick comparison between all these structures immediately indicates the
advantages of using C-C nanocomposites as follows: high surface area for Li-ion insertion leading to high capacity, nominal
volume change during charging/discharging resulting in stable
capacity, and excellent electrical conductivity for achieving fast
charge transport and, hence, high rate capability. Even a different morphology of carbon nanocages with nanographene shell
has shown similar properties.153 Addition of high-capacity materials (e.g., Sn) can further enhance the benefits obtained by
this form of composites. A hierarchial Sn@CNT nanostructure,
rooted in graphene, has delivered such results (Figure 20).154
The anode was able to offer stable capacities for at least 100
cycles at different current rates: from 0.1–5.0C. Reversible capacity of this hybrid anode was also very high – 1160 mAh/g
at 0.1C (100 mA/g) rate. Such high capacity could easily be
FIG. 20. Sn@CNT nanostructure rooted in graphene, as anode of Li-ion battery: (a) schematic of the synthesis process; (b)
comparison of capacity and stability of the anodes; and (c) stability of the anode at higher current rates. (Reprinted with permission
Zhou and Wang154 Copyright 2011: American Chemical Society.) (Color figure available online.)
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
Downloaded by [Hanyang University] at 01:50 10 May 2013
connected with the presence of high-capacity Sn-nanoparticles
in the anode. Further, the composite electrode maintained the
signature properties of C-C nanocomposites, i.e., high stability and excellent rate capability. Overall, C-C nanocomposites
electrodes, especially with addition of high-capacity materials
like Sn, appear to be promising for future anodic application in
Li-ion batteries.
4.5. Core-Shell Structures
Nanostructures of carbon, i.e., fullerene, CNTs, graphene,
have been used either individually or as a composite with any
other element or oxide or another C-based material, for possible
anodic applications in Li-ion batteries. Exceptionally high electrical and mechanical properties of CNTs and graphene have initiated another structural variety for this type of applications—a
core-shell type of structure. In this form of materials, nanostructured carbon provides easy flow paths for faster electron
movement and also accommodates high strains generated during
lithiation/de-lithiation by the other component in the structure.
153
This design appears interesting for materials like Si or Sn-based
nanostructures, as these materials have high theoretical lithiation capacity, but needs to overcome issues associated with low
conductivity and high volume expansion during lithiation. As
expected, this core-shell category of anode structures, involving
nanostructured carbon as one of its components, were mostly
used for Si and Sn-oxide based nanomaterials.
In one of the earlier attempts, carbon nanofibers (CNF) were
attached to the surface of Si nanoparticles and this structure
was used as anode in Li-ion battery.155 The process steps consisted of coating pyrolytic carbon (PC) on Si nanoparticles and
growth of CNFs on Si, followed by catalyst removal and further PC coating on CNFs (Figure 21). This Si-PC-CNT anode
structure demonstrated highest capacity of 1317 mAh/g and
a stable capacity of 1051, after 20 cycles (tested at a current
rate of 100 mA/g). Higher stability of this electrode, as compared to Si nanostructured electrodes, could be attributed to
the presence of CNFs, which offered flexible space to relieve
volumetric expansion strains of Si nanoparticles. Other possible morphological variations of Si-C core-shell structure could
FIG. 21. Comparison of different schemes to prepare Si-C core-shell type anode structures for Li-ion battery: (a) Si nanoparticles
coated with PC and CNFs grown on the particles (reprinted with permission from Jang et al.155 Copyright 2012: Elsevier); (b)
CNFs coated with amorphous Si (reprinted with permission from Cui et al.156 Copyright 2009: American Chemical Society); (c)
Si nanoparticle decorated vertically aligned CNTs (reprinted with permission from Wang and Kumta73 Copyright 2010: American
Chemical Society); (d) Si nanoparticles wrapped by carbon tubes (reprinted with permission from Wu et al.161 Copyright 2012:
American Chemical Society); and (e) TiC/C/Si nanofiber composite electrode (reprinted with permission from Yao et al.162
Copyright 2011: American Chemical Society). (Color figure available online.)
Downloaded by [Hanyang University] at 01:50 10 May 2013
154
I. LAHIRI AND W. CHOI
FIG. 22. Comparison of electrochemical performance of different Si-C core-shell type anode structures for Li-ion battery: (a) CNF
core-amorphous Si shell structure (reprinted with permission from Cui et al.156 Copyright 2009: American Chemical Society); (b)
Si nanowire coated with carbon (reprinted with permission from Huang et al.157 Copyright 2012: American Institute of Physics)
and cycling performance of Si nanoparticles wrapped by C structure at (c) C/5 rate and (d) 3C rate (reprinted with permission
from Hwang et al.160 Copyright 2012: American Chemical Society). (Color figure available online.)
involve Si nanowires (Si-NW), which created immense interest
in the Li-ion battery field.34 CNFs, coated with amorphous Si,
was proposed by Cui et al. for application as anode in Li-ion
batteries and the anode has offered excellent properties, both in
half-cell and full-cell modes.156 Stability and rate capability of
this hybrid anode structure was found to be much better than bare
Si-NW electrodes (Figure 22). The hybrid anode demonstrated
stable capacities of 1600 mAh/g at C/15 rate, 1300 mAh/g at
C/5 rate, and 800 mAh/g at 1C rate (1C = 2500 mA/g). At
C/15 rate, the anode had an area capacity of ∼4 mAh/cm2,
which is comparable with commercial batteries. CNF, as the
core of this structure, acted both as a mechanical support and
a low-resistance electron path, enhancing electrochemical performance of this electrode. In a slightly different morphology,
a carbon-coated Si-NW array film anode exhibited a reversible
capacity of 1326 mAh/g (Figure 22), after 40 cycles,157 which is
at par with CNF core-Si shell structure. Replacing Si-NWs with
Si nanoparticles, an amorphous carbon coated on Si nanoparticle anode158 or Si@SiOx/C nanocomposites core-shell structure
159
also delivered appreciable electrochemical performances. In
another effort, Si nanoparticles were deposited on CNTs and
used with binders and additives as anode material for Li-ion
battery.73 This hybrid anode offered more than 2000 mAh/g of
reversible capacity for first 25 cycles. The capacity faded down
after this stage, with a rate of 1.3%/cycle from 25–50 cycles
and at a reduced rate of 0.4%/cycle during 50–100 cyclesto a
final capacity of ∼1000 mAh/g after 100 cycles. Rate capacity of this anode was also encouraging, with ∼1000 mAh/g at
2.5C rate. It may be noted that the Si-C hybrid structure was
able to reduce the capacity fading problem of Si-NW anodes
substantially, but it could not be avoided fully. Future research
work needs to highlight this issue in order to materialize the
great promise offered by this type of material as an advanced
electrode for Li-ion batteries. Very recent research works have
shown good promise in solving this issue through introduction
of another novel morphology: Si nanoparticles wrapped with
carbon tubes (Figure 21), reported independently by two different research groups.160,161 In this structure, Si nanoparticles
get enough empty space to expand/contract during lithiation/delithiation. Since these particles are wrapped around by carbon
Downloaded by [Hanyang University] at 01:50 10 May 2013
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
tubes, they never get detached from the electrode and, thus, contribute continuously to the battery performance. On the other
hand, the carbon coating provides easy electron path, binds the
Si nanoparticles together and maintains the electrode integrity.
As expected, this novel structure has delivered exceptionally
high stability, tested up to 300 cycles and very high rate capability. This form of novel anode design holds promise for next
generation Li-ion batteries. Working further on the application
of Si-C core-shell kind of structure, Yao et al. designed a unique
TiC/C/Si nanofiber composite structure, which has exhibited
much higher and stable (0.08%/cycle fading rate) capacity as
Li-ion battery anode.162 This novel core-shell type nanocomposite anode structure showed ∼3000 mAh/g discharge capacity
and 92% of its capacity was retained, even after 100 cycles. Enhanced properties of this new design could be attributed to high
Li-ion insertion ability of the top layer of amorphous Si, which
received mechanical and electrical support from inside by TiC
and C, respectively. Combination of these three materials thus
prevented any structural degradation of the anode and ensured
faster electron kinetics, leading to excellent stability and high
rate capability.
The core-shell design was applied to Sn-oxide based structures, too. The initial attempt was to synthesize a SnO2 core/carbon-shell nanotube structure.163 The anode offered only
∼600 mAh/g capacity at 0.5C rate. However, it showed a very
stable behavior until 200 cycles, indicating that the pulverization
problem of SnO2 structure could probably be reduced significantly through this new core-shell structure. Almost a similar
structure, but having CNT as the core, amorphous Sn-oxide as
an over layer on CNTs and very little amount of Au deposited
on the Sn-oxide layer, have shown remarkable high rate capability.164 This unique anode delivered 467 and 392 mAh/g
capacities at 3600 and 7200 mA/g current rates, respectively.
Presence of Au was predicted as the reason for faster kinetics
and hence, better capacity at higher rates. Recent researches
proposed development of newer core-shell morphologies of Snoxide/C nanomaterials, with expectations of achieving better
electrochemical properties. One such novel structure is mesoporous SnO2 core consisting of nanoparticles and a C shell.165
Another variation could be RGO-mediated growth of Sn-core/Csheath coaxial nanocable.166 Even a SnO2 -C nanotube structure
has been developed for Li-ion battery applications.167 Apart
from offering excellent rate capabilities, these novel electrodes
also addressed the capacity-fading phenomenon of Sn-oxidebased anodes by reducing the degradation rate. However, further
research is needed before predicting SnO2 -C core-shell structure
as a future anode material for Li-ion batteries.
Core-shell form of structure was mostly popular for Si-C and
SnO2 -C kind of composite materials, although this form was
engaged in other compositions as well. These involve different oxides, viz. MnO2 , TiO2 , and RuO2 . A coaxial MnO2 -CNT
array was one of the few initial reports on core-shell type of
structures.168 Although this composite anode has shown higher
capacity than its individual components, still it had higher capac-
155
ity fading rate than only CNT anodes. In spite of this limitation
in stability, the interest created in the scientific community by
this novel design has led to development of many other varieties of core-shell structures, as has already been discussed in
this section. Almost similar kind of coaxial composite anode
structure was demonstrated for CNT-TiO2 , having CNTs as the
conducting core and porous TiO2 as the sheath.169 Like the CNTMnO2 coaxial structure, this anode also performed better than
its individual components. But, its overall performance was not
exciting enough, to be comparable with Si-C or SnO2 -C type
core-shell structures. However, its rate capability was observed
to be excellent, mostly due to the conducting CNT core. A better distribution of active material and conductive/strain relaxing
component could be achieved by the design of self-wound nano
membranes (SWNM) (Figure 23), proposed by Ji et al.,170 Although they have demonstrated the proof-of-concept structure
with RuO2 -C composite, but the principle should be applicable
to any kind of two-dimensional material. Owing to homogeneous distribution of RuO2 and C, this structure offered much
better electrochemical properties as an anode of Li-ion battery,
as compared to that by RuO2 powder.
Core-shell form of structure, especially the Si-C combination, demonstrated high promise to be considered as anode for
Li-ion batteries. Novel design and morphologies of materials
are being proposed to further enhance performance of such
electrode structures. Upcoming research endeavors into developments of new materials, morphologies, and device design will
accelerate direct application of this kind of material in future
Li-ion batteries.
5. OTHER CARBON-BASED ANODES
5.1. Graphite-based Composites with Different
Nanomaterials
Graphite is one of the three-dimensional allotropes of carbon that has been extensively used as anode material in Liion battery. Application of Li-intercalated graphite as an anode
material has been proposed in 1977.171 Since then, numerous
theoretical and experimental researches have been performed
to understand this system.172–175 Owing to the knowledge generated from all these efforts, today’s most commercial Li-ion
batteries use graphite as an anode material, in combination with
activated carbon and mesocarbon microbead (MCMB).
Graphite, being a bulk structure, seems to have an unexpected
presence in this article. Though graphite is not really known to
be used as a nanostructure in electrode applications of Li-ion
batteries, its composite with other nanomaterials have shown
improved electrochemical performances, demanding inclusion
in this article. Ultra-thin coatings (often at nanoscale level) of
metal oxides on natural graphite (NG) have enhanced performance of graphite-based electrodes.176–179 Al2 O3 and ZrO2 are
the most popular nano-coatings, applied on natural graphite,
as these are known to stabilize the SEI formed on NG surface by providing protection against undesirable reactions with
Downloaded by [Hanyang University] at 01:50 10 May 2013
156
I. LAHIRI AND W. CHOI
FIG. 23. A schematic of the process to fabricate self-wound nano membrane (SWNM) electrode for Li-ion batteries. (Reprinted
with permission from Ji et al.170 Copyright 2012: John Wiley and Sons.) (Color figure available online.)
electrolyte. Decomposition of SEI is often exothermic and initiates thermal runaway of Li-ion batteries. Thus, nanoscale oxide
coatings on NG improve two important properties of Li-ion batteries, viz. safety and long cycle stability. Jung et al. showed
that ultra-thin oxide coating can be applied on the composite
electrode itself, containing active materials, conductive additive
and binder (Figures 24a and b).179 This development offers a
simple route for industrial scale application of nano-coatings
on NG. Surface modification of NG by phosphorus (P) is also
known to stabilize SEI and improve stability of graphite based
anodes.180
Graphite can also be used as a composite, mostly using Si or
Sn nanoparticles with it.181,182 Nanoparticle addition enhances
reversible capacity of the electrodes and improves cycle performance of the batteries. These types of composite electrodes are
benefited from both graphite and the embedded nanoparticles.
While Si or Sn provides higher capacity for lithium insertion,
graphite mitigates the initial irreversibility and hysteresis between charge and discharge behavior. Impregnation of gelatinous Si into porous natural graphite has shown stable capacity
of 840 mAh/g for over 100 cycles, with an excellent efficiency
of over 99%.183 Porous structure of NG ensures presence of
Si on surface as well as inside the pores, aiding in a substantial improvement in capacity and stability (Figures 24c and d).
Lee et al. reported synthesis of a novel composite structure of
highly crystalline graphite, a filamentous carbon structure and
fullerene by dissolution-precipitation method from a carbon-
rich cast iron melt.184 The structure offered stable capacity of
305 mAh/g, very low first-cycle irreversible capacity (∼14%)
and very high coulombic efficiency of more than 99% after
5th cycle. However, electrochemical properties of this specific
electrode structure have been reported only up to ten cycles,
necessitating further investigation. Wide variety of researches
in the field of embedded active nanomaterials in another matrix
have led to few other interesting structures for anodic applications of Li-ion battery, such as spheroidal carbon, mesorporous
carbon, etc.
5.2. Spheroidal Carbon-based Anodes
Spheroidal carbon-based structures are one of the novel carbon morphologies for application as anode in Li-ion batteries.
Combining the benefits of C and Si, a spheroidal carbon-coated
Si nanocomposites electrode demonstrated high capacity as well
as good Coulombic efficiency.185 The composite electrode delivered an impressive specific capacity of 1489 mAh/g, even
after 20 cycles, while the Si-nanoparticles based anode decayed down to only 47 mAh/g capacity, in the same number
of cycles. However, it should be noted that the novel anode
structure also had substantial irreversible capacity of 29% and
could not essentially nullify the capacity fading issues. It was
thus important to move further ahead and to use the beneficial
effects of the spheroidal morphology in a different structure.
Merging the advantages of spheroidal morphology and a porous
Downloaded by [Hanyang University] at 01:50 10 May 2013
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
157
FIG. 24. (a) Nanoscale Al2 O3 coating (by Atomic Layer Deposition, ALD) on natural graphite-based composite electrode retains
electron flow path and enhances stability of SEI; (b) comparison of electrochemical performance of ALD-coated NG composite
electrodes at 50◦ C (reprinted with permission from Jung et al.179 Copyright 2010: John Wiley and Sons); (c) and (d) are SEM
images of porous natural graphite, before and after impregnation of gelatinous Si, respectively; and (e) cycling behavior and
efficiency of graphite-Si composite (for structure shown in “d” above) at 0.7C rate (reprinted with permission from Stangl et al.183
Copyright 2012: Elsevier). (Color figure available online.)
structure, a carbon nanocage structure with a nano-graphene
shell was synthesized as anode of Li-ion batteries.153 This new
morphology was expected to offer several benefits: (i) fast electron transport due to presence of nano-graphene shell and good
inter-cage contacts; (ii) fast ion movement owing to short diffusion distance offered by thin C shells; (iii) high Li-ion insertion
sites from high specific surface area of the structure; and (iv)
easy penetration and movement of electrolyte and ions through
the porous network of the anode. The best C-nanocage structure,
prepared at a temperature of 750◦ C, has shown a stable capacity of ∼575 mAh/g, for 60 cycles. Rate capability of this anode
was also very good. Specific capacities of ∼150 mAh/g and ∼60
mAh/g were achieved even at high rates of 5 A/g and 10 A/g,
respectively.
Another similar structure is nano-graphene constructed hollow carbon sphere (NGHC) (Figure 25).186 This unique morphology was synthesized through a precursor-controlled pyrolysis process, using silica/space/mesorporous silica spheres
as templates. These spheres had almost uniform size and two
walls: a thick outer mesoporous wall and a thin inner solid
wall. The outer wall included nano-channels, perpendicular to
the surface of the sphere, creating easy diffusion paths for Li+
ions from any direction. On the other hand, the solid inner wall
could enhance electron transport. With these dual benefits, these
spherical structures were anticipated to have better rate performance. The expectation was satisfied by an extraordinary 200
mAh/g capacity at 20C rate. Stability of this electrode, at different current rates, is also noteworthy. Even at 10C rate, the
anode consistently offered approximately 200 mAh/g capacity.
This novel anode structure can further be modified in future by
incorporating highly Li-active materials like Si or Sn, inside the
hollow interior.
5.3. Porous Carbon-Based Electrodes
Porous carbon structures have shown great promise as a new
carbon-based material for energy storage applications. Porosity increases active surface area and also allows easy diffusion
paths for ions. An ordered mesoporous carbon anode was reported to offer very high specific capacity of 1100 mAh/g, at
a current rate of 100 mA/g.187 The capacity was also stable
enough for the first 20 cycles, with low capacity fading rate of
0.075%/cycle. Such high capacity and acceptable stability could
be attributed to high surface area (BET surface area 1030 m2/g)
Downloaded by [Hanyang University] at 01:50 10 May 2013
158
I. LAHIRI AND W. CHOI
FIG. 25. (a) Schematic of synthesis and lithiation/de-lithiation in nano-graphene constructed hollow carbon sphere (NGHC) anode
for Li-ion batteries and (b) rate capability of the same electrodes, finally treated at 700◦ C (NGHCs-700) and 1000◦ C (NGHCs1000), compared with sucrose-derived hollow carbon spheres (SDHCs) and commercially available natural graphite. (Reprinted
with permission from Yang et al.186 Copyright 2012: John Wiley and Sons.)
of the mesoporous structure. Further development of porous carbon structure led to synthesis of a hierarchically porous carbon
into a three-dimensional network of meso- as well as macropores.188 The anode offered a stable capacity of ∼500 mAh/g,
after 40 cycles, which is almost twice the capacity of that obtained from graphite. Moreover, rate capability of the anode was
excellent with acceptable capacity even up to a high rate of 60C
(Figure 26), making them suitable for high power applications.
Such a high power capacity was related to distribution and connectivity of different size of pores, which offered an easy path
for Li-ion diffusion and ample sites for Li-ion attachment. A
morphologically different structure of superfine expanded
graphite has also shown similar high rate capability (up to 60C)
as anode of Li-ion batteries.189 This unique anode structure
is characterized by thin (2–3 nm) graphitic ribbons of several
micrometers length, having high surface area and mesopores
(2–5 nm size), similar to the mesoporous structures. Many other
similar porous carbon structure have been reported to offer
good capacity and excellent rate capability, making this category of material an attractive choice for next-generation Li-ion
batteries.190,191
Promise of porous C-based structures immediately attracted
research efforts to incorporate other high-theoretical capacity
(lithiation) metal or metal oxide nanoparticles inside the porous
network, with an aim to further lift the capacity level of the
anodes.192,193 Such a study on inserting metallic Sn particles
inside porous multichannel carbon microtubes has shown remarkable improvement in stability and high rate capability of
the anode.194 Even at a high rate of 10C, this hybrid porous
structure has offered stable capacity of ∼300 mAh/g. Much
better electrochemical properties were reported for a structure containing Si nanoparticles inside C-based rigid spheres,
with interconnected internal channels for easy and fast ac-
cess of bulk structure by Li+ ions.195 The anode demonstrated
∼1400 mAh/g capacity for 100 cycles without any appreciable decay in its capacity. Even its volumetric capacity of
1270 mAh/cm3 (at C/20 rate) is much higher than that offered
by graphite in this study (∼620 mAh/cm3). A porous carbon
scaffold-based Si anode structure showed some degree of capacity fading during long cycle operations, although strains of
lithiation/de-lithiation in Si was claimed to be accommodated
by the scaffold structure.196 However, this new morphology
of anode was successful in delivering very high capacity and
good rate capability. Similar concept applied to α-Fe2 O3 /hollow
amorphous carbon structure has delivered excellent capacity,
stability, and rate capability, owing to the porous nature of the
binding carbon material.197 It may be important to note here that
implementation of porous carbon-structured nanocomposites
material have also delivered exciting properties for cathode
applications in Li-ion batteries.198–202 Excellent properties offered by these novel porous architectures have created enormous
enthusiasm for development of new structures with improved
properties.
6. SCOPE AND FUTURE
Nano carbon materials offer many advantages, e.g., performing as a reversible sink to Li-ion insertion, offering its conducting path as a fast way for electron transfer, accommodating
strains generated by other materials (such as Si or SnO2 ) through
its flexible structure and allowing free and fast movement of ions
through its porous structure. Further, carbon shows very low volume expansion/contraction during lithiation/de-lithiation and,
thus, it can work as an ideal material for anodes of Li-ion batteries. All these exciting properties of carbon-based nanomaterials have generated huge research efforts to develop a suitable
Downloaded by [Hanyang University] at 01:50 10 May 2013
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
159
FIG. 26. High rate capacity of (a) hierarchically porous carbon anode structure (reprinted with permission from Hu et al.188
Copyright 2007: John Wiley and Sons); (b) superfine expanded graphite structure (reprinted with permission from Kaskhedikar
et al.189 Copyright 2011: John Wiley and Sons); and (c) stable capacity and high rate capability (inset) of Sn particles encapsulated
in porous multichannel carbon microtubes anode (reprinted with permission from Yu et al.194 Copyright 2009: American Chemical
Society). (Color figure available online.)
high-performance anode material for future Li-ion batteries. A
variety of carbon nanostructures, starting from individual CNTs,
graphene, and their composites to novel architectures like coreshell structure and porous carbon-based materials have been
studied widely for their potential application as anode in next
generation Li-ion batteries. Many of these structures have shown
good promise to replace conventionally used graphite-based anodes. Directly grown CNTs on current collectors have shown
promise to add more safety to the battery by avoiding organic
binders along with high and extremely stable capacity. Composite anodes like CNT-Si or CNT-graphene has shown very
high capacity, although with a certain degree of capacity fading.
Novel design modifications, such as Si-C core-shell structure
or Si nanoparticles inside a porous carbon network, have often
been proposed as a solution to the capacity degradation issue.
Great promise shown by these new materials have generated
high interest for continuing research in this field, in order to
achieve the best structure.
Carbon nanomaterials hold good promise as an anode material for Li-ion batteries. However, issues remain for application
of these materials in Li-ion batteries. It is necessary for carbon
nanostructures to surpass the theoretical maximum volumetric
Downloaded by [Hanyang University] at 01:50 10 May 2013
160
I. LAHIRI AND W. CHOI
capacity of graphite (which is 833 mAh/cm3),105 to be a suitable alternative/replacement for graphite anodes. Further, these
anode should also be able to offer comparable stability for thousands of cycles, provide much better safety and most importantly, generate high energy and power, which can potentially
revolutionize the hybrid and all-electric automobile industries.
Volumetric capacity, instead of gravimetric capacity, becomes
much more important parameter from the practical point of
view of restricting the battery size to a reasonable and acceptable limit.203 C-based materials are often known as low-density
materials, which lead to realization of low volumetric capacity
and low volumetric energy/power density from these devices.
Moreover, most of the researches demonstrate feasibility of the
proposed materials through a small-scale, proof-of-concept battery. Scaling-up of the synthesis process to industrial level often results in additional issues, making it difficult to reproduce
the same structure and properties for a commercial size Li-ion
battery. Future research should concentrate on proposing solutions to these actual problems to establish the nano-carbonbased materials as a viable alternative to graphite. New architectures204 or structural modifications205 are being presented to
counter these issues. The present authors are also working towards development of new electrode architecture to alleviate
these problems of presently known nano-C-based electrodes.
The next 3–4 years are going to be extremely important to know
new directions on development of next-generation Li-ion batteries, which can bridge the gap between energy/power demand
and availability, for future electronics and automobile industries.
ACKNOWLEDGMENTS
This research was, in part, supported by WCU (World Class
University) program through the Korea Science and Engineering
Foundation funded by the Ministry of Education, Science and
Technology (R31-2008-000-10092) and U.S. Air Force Office
of Science Research Grant (FA9550-09-1-0544).
REFERENCES
1. M. Z. Jacobson, Review of solutions to global warming, air
pollution, and energy security, Energy Environ. Sci., 2, 148
(2009).
2. Committee on Advanced Materials for Our Energy Future, Advanced Materials For Our Energy Future. TMS Energy. [Online]
May 31, 2010. [Cited: January 23, 2012.] http://energy.tms.org/
docs/pdfs/Advanced Materials For Our Energy Future.pdf.
3. Energy materials blue ribbon panel, Linking transformational
materials and processing for an energy-efficient and low-carbon
economy: Creating the vision and accelerating realization. TMS
Energy. [Online] September 6, 2010. [Cited: Jnauary 23, 2012.]
http://energy.tms.org/docs/pdfs/VisionReport2010.pdf.
4. J.-M. Tarascon and M. Armand, Issues and challenges facing
rechargeable lithium batteries, Nature, 414, 359 (2001).
5. M. Armand and J.-M. Tarascon, Building better batteries, Nature,
451, 652 (2008).
6. M. King, Advanced rechargeable battery market: Emerging technologies and trends worldwide. Nanotechnology Now. [Online]
August 3, 2009. [Cited: January 21, 2012.] http://www.nanotechnow.com/news.cgi?story id=34106.
7. C. Cho, Koreans firms set to lead rechargeable battery market. The
Korea Hearald. [Online] July 26, 2010. [Cited: January 21, 2012.]
http://www.koreaherald.com/business/Detail.jsp?newsMLId=
20100726000900.
8. S. W. Lee, B. M. Gallant, H. R. Byon, P. T. Hammond, and Y.
Shao-Horn, Nanostructured carbon-based electrodes: brdging the
gap between thin-film lithium-ion batteries and electrochemical
capacitors, Ener. Environ. Sci., 4, 1972 (2011).
9. M. Rosenberg and E. Garcia. Known lithium deposits can cover
electric car boom. Reuters. [Online] February 11, 2010. [Cited:
April 11, 2012.] http://www.reuters.com/article/2010/02/11/uslithium-latam-idUSTRE61A5AY20100211.
10. I. Lahiri, S. Das, C. Kang, and W. Choi, Application of carbon
nanostructures—energy to electronics, JOM, 63, 70 (2011).
11. B. Scrosati and J. Garche, Lithium batteries: Status, prospects
and future, J. Power Sour., 195, 2419 (2010).
12. B. Scrosati, Recent advances in lithium ion battery materials,
Electrochimica Acta, 45, 2461 (2000).
13. M. Wakihara, Recent advances in lithium ion batteries, Mater.
Sci. Eng. R, R33, 109 (2001).
14. S. Panero, B. Scrosati, M. Wachtler, and F. Croce, Nanotechnology for the progress of lithium batteries R&D, J. Power Sour.,
129, 90 (2004).
15. E. Stura and C. Nicolini, New nanomaterials for light weight
lithium batteries, Anal. Chimica Acta, 568, 57 (2006).
16. C. Jiang, E. Hosono, and H. Zhou, Nanomaterials for Li-ion
batteries, Nano Today, 1, 28 (2006).
17. T. Ohzuku and R. J. Brodd, An overview of positive-electrode
materials for advanced lithium-ion batteries, J. Power Sour., 174,
449 (2007).
18. J. W. Fergus, Recent developments in cathode materials for
lithium ion batteries, J. Power Sour., 195, 939 (2010).
19. H.-K. Song, K. T. Lee, M. G. Kim, L. F. Nazar, and J. Cho,
Recent progress in nanostructured cathode materials for lithium
secondary batteries, Adv. Funct. Mater., 20, 3818 (2010).
20. A. S. Arico, P. Bruce, B. Scrosati, J.-M. Tarascon, and W. V.
Schalkwijk, Nanostructured materials for advanced energy conversion and storage devices, Nat. Mater., 4, 366 (2005).
21. K. Kinoshita and K. Zaghib, Negative electrodes for Li-ion batteries, J. Power Sour., 110, 416 (2002).
22. J. L. Tirado, Inorganic materials for the negative electrode of
lithium-ion batteries: state-of-the-art and future prospects, Mater.
Sci. Eng. R, 40, 103 (2003).
23. S. Flandrois and B. Simon, Carbon materials for lithium-ion
rechargeable batteries, Carbon, 37, 165 (1999).
24. M. Endo, C. Kim, K. Nishimura, T. Fujino, and K. Miyashita, Recent development of carbon materials for Li ion batteries, Carbon,
38, 183 (2000).
25. N. A. Kashkhedikar and J. Maier, Lithium storage in carbon
nanostructures, Adv. Mater., 21, 2664 (2009).
26. H. Ikeda, T. Saito, and H. Tamura, in Proc. Manganese Dioxide
Symp. Vol. 1, Kozawa A. and Brodd, R. H., Eds., IC Sample
Office, Cleveland, OH, (1975).
27. F. G. Will, Hermetically sealed secondary battery with lanthanum
nickel anode, U.S. Patent 3874958 (1975).
Downloaded by [Hanyang University] at 01:50 10 May 2013
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
28. D. W. Murphy, F. J. DiSalvo, J. N. Carides, and J. V. Waszczak,
Topochemical reactions of rutile related structures with lithium,
Mat. Res. Bull., 13, 1395 (1978).
29. M. Lazzari and B. Scrosati, A cyclable lithium organic electrolyte
cell based on two intercalation electrodes, J. Electrochem. Soc.,
127, 773 (1980).
30. P. G. Bruce, B. Scrosati, and J.-M. Tarascon, Nanomaterials for
rechargeable lithium batteries, Angew. Chem. Int. Ed., 47, 2930
(2008).
31. T. Brousse, D. Defives, L. Pasquereau, S. M. Lee, U. Herterich,
and D. M. Schleich, Metal oxide anodes for Li-ion batteries,
Ionics, 3, 332 (1997).
32. D. Larcher, S. Beattie, M. Morcrette, K. Edstrom, J. C. Jumas,
and J.-M. Tarascon, Recent findings and prospects in the field of
pure metals as negative electrodes for Li-ion batteries, J. Mater.
Chem., 17, 3759 (2007).
33. M. Winter, J. O. Besenhard, M. E. Spahr, and P. Novak, Insertion
electrode materials for rechargeable lithium batteries, Adv. Mater.,
10, 725 (1998).
34. C. K. Chan, H. Peng, G. Liu, K. McIlwrath, X. F. Zhang, R. A.
Huggins, and Y. Cui, High-performance lithium battery anodes
using silicon nanowires, Nat. Nanotechol., 3, 32 (2008).
35. C. K. Chan, X. F. Zhang, and Y. Cui, High capacity Li ion battery
anodes using Ge nanowires, Nano Lett., 8, 307 (2008).
36. K. T. Lee and J. Cho, Roles of nanosize in lithium reactive nanomaterials for lithium ion batteries, Nano Today, 6, 28
(2011).
37. Y. Wang, H. Li, P. He, E. Hosono, and H. Zhou, Nano active
materials for lithium-ion batteries, Nanoscale, 2, 1294 (2010).
38. A. S. Arico, P. Bruce, B. Scrosati, J.-M. Tarascon, and W. Van
Schalkwijc, Nanostructured materials for advanced energy conversion and storage devices, Nat. Mater., 4, 366 (2005).
39. F. Jiao and P. G. Bruce, Mesoporous crystalline β-MnO2—a
reversible positive electrode for rechargeable lithium batteries,
Adv. Mater., 19, 657 (2007).
40. P. Balaya, A. J. Bhattacharyya, J. Jamnik, Y. F. Zhukovskii, E.
A. Kotomin, and J. Maier, Nano-ionics in the context of lithium
batteries, J. Power Sour., 159, 171 (2006).
41. J. Maier, Nanoionics: ion transport and electrochemical storage
in confined systems, Nat. Mater., 4, 805 (2005).
42. N. Meethong, H.-Y. S. Huang, W. C. Carter, and Y.-M.
Chiang, Size-dependent lithium miscibility gap in nanoscale
Li1−xFePO4 , Electrochem. Soild-State Lett., 10, A134 (2007).
43. G. Kobayashi, S.-I. Nishimura, M.-S. Park, R. Kanno, M.
Yashima, T. Ida, and A. Yamada, Isolation of solid solution
phases in size-controlled LixFePO4 at room temperature, Adv.
Func. Mater., 19, 395 (2009).
44. M. S. Dresselhaus, G. Dresselhaus, and P. C. Eklund, Science of
Fullerenes and Carbon Nanotubes, Academic Press, San Diego
(1996).
45. R. O. Loufty and S. Katagiri, Fullerene materials for lithium-ion
battery applications, in Perspectives in Fullerene Nanotechnology, Part VII, Osawa, E., Eds., Kluwer Academic Publishers,
Dordrecht, The Netherlands, 357 (2002).
46. S.-I. Kawabe, T. Kawai, R.-I. Sugimoto, E. Yagasaki, and K.
Yoshino, Electrochemical properties of fullerene derivative polymers as electrode materials, Jap. J. Appl. Phys. Part 2 Lett., 36,
L1055 (1997).
161
47. A. A. Arie and J. K. Lee, Fullerene film as a coating material
for silicon thick film anodes for lithium ion batteries, Mater. Sci.
Technol. Conf. Exhib. 1, 294 (2009).
48. A. A. Arie and J. K. Lee, A study of Li-ion diffusion kinetics
in the fullerene-coated Si anodes of Lithium ion batteries, Phys.
Scr., T139, 014013 (2010).
49. A. A. Arie and J. K. Lee, Electrochemical properties of fullerene
coated silicon thick film for anode material of lithium secondary
batteries, ECS Trans., 25, 111 (2010).
50. A. A. Arie, O. M. Vovk, J. O. Song, B. W. Cho, and J. K. Lee,
Carbon film covering originated from fullerene C60 on the surface of lithium metal anode for lithium secondary batteries, J.
Electroceram., 23, 248 (2009).
51. A. A. Arie, W. Chang, and J. K. Lee, Effect of fullerene coating
on silicon thin film anodes for lithium rechargeable batteries, J.
Solid State Electrochem., 14, 51 (2010).
52. A. A. Arie, O. M. Vovk, and J. K. Lee, sputtering, Surface-coated
silicon anodes with amorphous carbon film prepared by fullerene
C60, J. Electrochem. Soc., 157, A660 (2010).
53. G. Maurin, Ch. Bousquet, F. Henn, P. Bernier, R. Almairac, and
B. Simon, Electrochemical intercalation of lithium into multiwall
carbon nanotubes, Chem. Phys. Lett., 312, 14 (1999).
54. F. Beguin, K. Metenier, R. Pellenq, S. Bonnamy, and E. Frackowiak, Lithium insertion in carbon nanotubes, Mol. Cryst. Liq.
Cryst., 340, 547 (2000).
55. Z.-H. Yang and H.-Q. Wu, Electrochemical intercalation of
lithium into raw carbon nanotubes, Mater. Chem. Phys., 71, 7
(2001).
56. E. Frackowiak and F. Beguin, Electrochemical storage of energy
in carbon nanotunes and nanostructured carbons, Carbon, 40,
1775 (2002).
57. H.-C. Shin, M. Liu, B. Sadanadan, and A. M. Rao, Electrochemical insertion of lithium into multi-walled carbon nanotubes prepared by catalytic decomposition, J. Power Sour., 112, 216 (2002).
58. W. X. Chen, J. Y. Lee, and Z. Liu, Electrochemical Lithiation and
de-lithiation of carbon nanotube-Sn2Sb nanocomposites, Electrochem. Comm., 4, 260 (2002).
59. W. X. Chen, J. Y. Lee, and Z. Liu, The nanocomposites of carbon
nanotube with Sb and SnSb0.5 as Li-ion battery anodes, Carbon,
41, 959 (2003).
60. Z. P. Guo, Z. W. Zhao, H. K. Liu, and S. X. Dou, Electrochemical
lithiation and de-lithiation of MWNT-Sn/SnNi nanocomposites,
Carbon, 43, 1392 (2005).
61. M. S. Park, S. A. Needham, G.-X. Wang, Y.-M. Kang, J.-S. Park,
S.-X. Dou, and H.-K. Liu, Nanostructured SnSb/carbon nanotube
composites synthesized by reductive precipitation for lithium-ion
batteries, Chem. Mater., 19, 2406 (2007).
62. Y. NuLi, J. Yang, and M. Jiang, Synthesis and characterization of
Sb/CNT and Bi/CNT composites as anode materials for lithiumion batteries, Mater. Lett., 62, 2092 (2008).
63. Y. Zhang, X. G. Zhang, H. L. Zhang, Z. G. Zhao, F. Li,
C. Liu, and H. M. Cheng, Composite anode material of silicon/graphite/carbon nanotubes for Li-ion batteries, Electrochimica Acta, 51, 4994 (2006).
64. J. Y. Eom, J. W. Park, H. S. Kwon, and S. Rajendran, Electrochemical insertion of lithium into multiwalled carbon nanotube/silicon
composites produced by ball milling, J. Electrochem. Soc., 153,
A1678 (2006).
Downloaded by [Hanyang University] at 01:50 10 May 2013
162
I. LAHIRI AND W. CHOI
65. J. Shu, H. Li, R. Yang, Y. Shi, X. Huang, Cage-like carbon nanotubes/Si composite as anode material for lithium ion batteries,
Electrochem. Commun., 8, 51 (2006).
66. W. Wang and P. N. Kumta, Reversible high capacity nanocomposite anodes of Si/C/SWNTs for rechargeable Li-ion batteries,
J. Power Sour., 172, 650–658 (2007).
67. S. Y. Chew, S. H. Ng, J. Wang, P. Novak, F. Krumeich, S. L. Chou,
J. Chen, and H. K. Liu, Flexible free-standing carbon nanotube
films for model lithium-ion batteries, Carbon, 47, 2976–2983
(2009).
68. L.-F. Cui, R. Ruffo, C. K. Chan, H. Peng, and Y. Cui,
Crystalline-amorphous core-shell silicon nanowires for high capacity and high current battery electrodes, Nano Lett., 9, 491–
495 (2009).
69. T. Song, J. Xia, J.-H. Lee, D. H. Lee, M.-S. Kwon, J.-M. Choi,
J. Wu, S. K. Doo, H. Chang, W. I. Park, D. S. Zang, H. Kim, Y.
Huang, K.-C. Hwang, J. A. Rogers, and U. Paik, Arrays of sealed
silicon nanotubes as anodes for lithium ion batteries, Nano Lett.,
10, 1710–1716 (2010).
70. L.-F. Cui, L. Hu, J. W. Choi, and Y. Cui, Light-weight freestanding carbon nanotube-silicon films for anodes of lithium ion
batteries, ACS Nano, 4, 3671–3678 (2010).
71. J. Rong, C. Masarapu, J. Ni, Z. Zhang, and B. Wei, Tandem
structure of porous silicon film on single-walled carbon nanotube
macrofilms for lithium-ion battery applications, ACS Nano, 4,
4683–4690 (2010).
72. C. Martin, O. Crosnier, R. Retoux, D. Belanger, D. M. Schleich, and T. Brousse, Chemical coupling of carbon nanotubes and
silicon nanoparticles for improved negavtive electrode performance in lithium-ion batteries, Adv. Funct. Mater., 21, 3524–3530
(2011).
73. W. Wang and P. N. Kumta, Nanostructured hybrid silicon/carbon
nanotube heterostructures: Reversible high-capacity lithium-ion
anodes, ACS Nano, 4, 2233–2241 (2010).
74. C. K. Chan, R. N. Patel, M. J. O’Connell, B. A. Korgel, and
Y. Cui, Solution-graon silicon nanowires for lithium-ion battery
anodes, ACS Nano, 4, 1443–1450 (2010).
75. J. E. Trevey, K. W. Rason, C. R. Stoldt, and S.-H. Lee, Improved
performance of all-solid-state lithium-ion batteries using nanosilicon active material with multiwalled-carbon-nanotubes as a conductive additive, Electrochem. Solid-State Lett., 13, A154 (2010).
76. I. Lahiri, Prospects of oxide materials in Li-ion batteries, Am.
Ceram. Soc. Bull., 89, 17 (2010).
77. J. Fan, T. Wang, C. Yu, B. Tu, Z. Jiang, and D. Zhao, Ordered, nanostructured tin-based pxides/carbon composite as the
negative-electrode material for lithium-ion batteries, Adv. Mater.,
16, 1432 (2004).
78. Y. Fu, R. Ma, Y. Shu, Z. Cao, and X. Ma, Preparation and characetrization of SnO2/carbon nanotube composite for lithium ion battery applications, Mater. Lett., 63, 1946
(2009).
79. G. Du, C. Zhong, P. Zhang, Z. Guo, Z. Chen, and H. Liu, Tin dioxide/carbon nanotube composites with high uniform SnO2 loading
as anode materials for lithium ion batteries, Electrochimica Acta,
55, 2582 (2010).
80. H.-X. Zhang, C. Feng, Y.-C. Zhai, K.-L. Jiang, Q.-Q. Li, and
S.-S. Fan, Cross-stacked carbon nanotube sheets uniformly
loaded with SnO2 nanoparticles: A novel binder-free and high-
81.
82.
83.
84.
85.
86.
87.
88.
89.
90.
91.
92.
93.
94.
95.
capacity anode material for lithium-ion batteries, Adv. Mater., 21,
2299 (2009).
M.-S. Wu, P.-C. J. Chiang, J.-T. Lee, and J.-C. Lin, Synthesis of
manganese oxide electrodes with interconnected nanowire structure as an anode material for rechargeable lithium ion batteries,
J. Phys. Chem. B, 109, 23279 (2005).
H. Li, P. Balaya, and J. Maier, Li-storage via heterogeneous reaction in selected binary metal fluorides and oxides, J. Electrochem.
Soc., 151, A1878 (2004).
H. Xia, M. O. Lai, and L. Lu, Nanoflaky MnO2/carbon nanotube
nanocomposites as anode materials for lithium-ion batteries, J.
Mater. Chem., 20, 6896 (2010).
J. Guo, Q. Liu, C. Wang, and M. R. Zachariah, Interdispersed
amorphous MnOx-carbon nanocomposites with superior electrochemical performance as lithium- storage material, Adv. Func.
Mater., 22, 803 (2012).
S.-F. Zheng, J.-S. Hu, L.-S. Zhong, W.-G. Song, L.-J. Wan, and Y.G. Guo, Introducing dual functional CNT networks into CuO nanomicrospheres toward superior electrode materials for lithiumion batteries, Chem. Mater., 20, 3617 (2008).
S. Venkatachalam, H. Zhu, C. Masarapu, K. Hung, Z. Liu, K. Suenaga, and B. Wei, In-situ formation of sandwiched structures of
nanotube.CuxOy/Cu composites for lithium battery applications,
ACS Nano, 3, 2177 (2009).
C. Li, N. Sun, J. Ni, J. Wang, H. Chu, H. Zhou, M. Li, and Y. Li,
Controllable preparation and properties of composite materials
based on ceria nanoparticles and carbon nanotubes, J. Solid State
Chem., 181, 2620 (2008).
Q. Gao, L. Yang, X. Lu, J. Mao, Y. Zhang, Y. Wu, and Y. Tang,
Synthesis, characterization and lithium-storage performance of
MoO2/carbon hybrid nanowires, J. Mater. Chem., 20, 2807
(2010).
S. Ding, J. S. Chen, and X. W. (David) Lou, One-dimensional hierarchial structures composed of novel metal oxide nanosheets on
a carbon nanotube backbon and their lithium-storage properties,
Adv. Func. Mater., 21, 4120 (2011).
S. R. Sivakkumar and D.-W. Kim, Polyaniline/carbon nanotube
composite cathode for rechargeable lithium polyer batteries assembled with gel polymer electrolyte, J. Electrochem. Soc., 154,
A134 (2007).
Md. N. Hyder, S. W. Lee, F. C. Cebeci, D. J. Schmidt, Y. ShaoHorn, and P. T. Hammond, Layer-by-layer assembled polyaniline nanofiber/multiwall carbon nanotube thin film electrodes for
high-power and high-energy storage applications, ACS Nano, 5,
8552 (2011).
A. Goyal, A. L. M. Reddy, and P. M. Ajayan, Flexible carbon
nanotube-Cu2O hybrid electrodes for Li-ion batteries, Small, 7,
1709 (2011).
X. Li, F. Gittleson, M. Carmo, R. C. Sekol, and A. D. Taylor,
Scalable fabrication of multifunctional freestanding carbon nanotube/polymer composite thin films for energy conversion, ACS
Nano, 6, 1347 (2012).
V. L. Pushparaj, M. M. Shaijumon, A. Kumar, S. Murugesan, L.
Ci, R. Vajtai, R. J. Lindhardt, O. Nalamasu, and P. M. Ajayan,
Flexible energy storage devices based on nanocomposite paper,
Proc. Natl. Acad. Sci. Amer., 104, 13574 (2007).
S. S. Zhang and T. R. Jow, Study of poly(acrylonitrilemethyl methacrylate) as binder for graphite anode and
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
96.
97.
98.
99.
Downloaded by [Hanyang University] at 01:50 10 May 2013
100.
101.
102.
103.
104.
105.
106.
107.
108.
109.
110.
111.
LiMn2O4 cathode of Li-ion batteries, J. Power Sour., 109, 422
(2002).
A. Guerfi, M. Kaneko, M. Petitclerc, M. Mori, and K. Zaghib,
LiFePO4 water-soluble binder electrode for Li-ion batteries, J.
Power Sour., 163, 1047 (2007).
S. S. Zhang, K. Xu, and T. R. Jow, Evaluation on a water-based
binder for the graphite anode of Li-ion batteries, J. Power Sour.,
138, 226 (2004).
E. P. Roth, D. H. Doughty, and J. Franklin, DSC Investigation
of exothermic reactions occurring at elevated temperatures in
lithium-ion anodes containing PVDF-based binders, J. Power
Sour., 134, 222 (2004).
I. Lahiri, D. Lahiri, S. Jin, A. Agarwal, and W. Choi, Carbon
nanotubes: How strong is their bond with the substrate?, ACS
Nano, 5, 780 (2011).
I. Lahiri, R. Seelaboyina, J. Y. Hwang, R. Banerjee, and W. Choi,
Enhanced field emission from multi-walled carbon nanotubes
grown on pure copper substrate, Carbon, 48, 1531 (2010).
I. Lahiri, S.-W. Oh, J. Y. Hwang, S. Cho, Y.-K. Sun, R. Banerjee,
and W. Choi, High capacity and excellent stability of lithium ion
battery using interface-controlled binder-free multiwall carbon
nanotubes grown on copper, ACS Nano, 4, 3440 (2010).
I. Lahiri, S.-M. Oh, J. Y. Hwang, C. Kang, H. Jeon, R. Banerjee,
Y.-K. Sun, and W. Choi, Ultrathin alumina coated carbon nanotubes as negative electrodes for high capacity and safe Li-ion
battery, J. Mater. Chem., 21, 13621 (2011).
J. Chen, Y. Liu, A. I. Minett, C. Lynam, J. Wang, and G. G.
Wallace, Flexible, aligned carbon nanotube/conducting polymer
electrodes for a lithium-ion battery, Chem. Mater., 19, 3595
(2007).
C. Masarapu, V. Subramanian, H. Zhu, amd B. Wei, Long-cycle
electrochemical behavior of multiwall carbon nanotubes synthesized on stainless steel in Li ion batteries, Adv. Func. Mater., 19,
1008 (2009).
D. T. Welna, L. Qu, B. E. Taylor, L. Dai, and M. F. Durstock,
Vertically aligned carbon nanotube electrodes for lithium-ion batteries, J. Power Sour., 196, 1455 (2011).
R. A. DiLeo, A. Castiglia, M. J. Ganter, R. E. Rogers, C. D.
Cress, R. P. Raffaelle, and B. J. Landi, Enhanced capacity and
rate capability of carnon nanotube based anodes with titanium
contacts for lithium ion batteries, ACS Nano, 4, 6121 (2010).
H. Zhang, G. Cao, Z. Wang, Y. Yang, Z. Shi, and Z. Gu, Carbon
nanotube array anodes for ligh-rate Li-ion batteries, Electrochimica Acta, 55, 2873 (2010).
S. W. Lee, N. Yabuuchi, B. M. Gallant, S. Chen, B.-S. Kim, P.
T. Hammond, and Y. Shao-Horn, High-power lithium batteries
from functionalized carbon-nanotube electrodes, Nat. Nanotech.,
5, 531 (2010).
B. J. Landi, M. J. Ganter, C. M. Schauerman, C. D. Cress, and R.
P. Raffaelle, Lithium ion capacity of single wall carbon nanotube
paper electrodes, J. Phys. Chem. C, 112, 7509 (2008).
J. Zhou, H. Song, B. Fu, B. Wu, and X. Chen, Synthesis and
high-rate capability of quadrangular carbon nanotubes with one
open end as anode materials for lithium-ion batteries, J. Mater.
Chem., 20, 2794 (2010).
E. J. Yoo, J. Kim, E. Hosono, H.-S. Zhoi, T. Kudo, and I. Honma,
Large reversible Li storage of graphene nanosheet families for use
in rechargeable lithium ion batteries, Nano Lett., 8, 2277 (2008).
163
112. T. Bhardwaj, A. Antic, B. Pavan, V. Barone, and B. D. Fahlman,
Enhanced electrochemical lithium strorage by graphene nanoribbons, J. Amer. Chem. Soc., 132, 12556 (2010).
113. A. L. M. Reddy, A. Srivastava, S. R. Gowda, H. Gullapalli, M.
Dubey, and P. M. Ajayan, Synthesis of nitrogen-doped graphene
films for lithium battery application, ACS Nano, 4, 6337 (2010).
114. H. Wang, C. Zhang, Z. Liu, L. Wang, P. Han, H. Xu, K. Zhang, S.
Dong, J. Yao, and G. Cui, Nitrogen-doped graphene nanosheets
with excellent lithium storage properties. J. Mater. Chem., 21,
5430 (2011).
115. Z.-S. Wu, W. Ren, L. Xu, F. Li, and H.-M. Cheng, Doped graphene
sheets as anode materials with superhigh rate and large capacity
for lithium ion batteries, ACS Nano, 5, 5463 (2011).
116. Y. F. Li, Z. Zhou, and L. B. Wang, CN(x) nanotubes with pyridinelike structures: p-type semiconductors and Li storage materials,
J. Chem. Phys., 129, 104703 (2008).
117. L. Tang, Y. Wang, Y. Li, H. Feng, J. Liu, and J. Li, Preparation,
structure, and electrochemical properties of reduced graphene
sheet films, Adv. Func. Mater., 19, 1 (2009).
118. S. Yin, Y. Zhang, J. Kong, C. Zou, C. M. Li, X. Lu, J. Ma, F. Y. C.
Boey, and X. Chen, Assembly of graphene sheets into hierarchial
structures for high-performance energy storage, ACS Nano, 5,
3831 (2011).
119. X. Zhao, C. M. Hayner, M. C. Kung, and H. H. Kung,
Flexible holey graphene paper electrodes with enhanced rate
capability for energy storage applications, ACS Nano, 5, 8739
(2011).
120. E. Pollak, B. Geng, K.-J. Jeon, I. T. Lucas, T. J. Richardson, F.
Wang, and R. Kostecki, The intercalation of Li+ with single-layer
and few-layer graphene, Nano Lett., 10, 3386 (2010).
121. A. T. Valota, I. A. Kinloch, K. S. Novoselov, C. Casiraghi, A.
Eckmann, E. W. Hill, and R. A. W. Dryfe, Electrochemical behavior of monolayer and bilayer graphene, ACS Nano, 5, 8809
(2011).
122. C. Uthaisar and V. Barone, Edge effects on the characteristics of
Li diffusion in graphene, Nano Lett., 10, 2838 (2010).
123. Y. Kubota, N. Ozawa, H. Nakanishi, and H. Kasai, Quantum states
and diffusion of lithium atom motion on a graphene, J. Phys. Soc.
Japan, 79, 014601 (2010).
124. S.-M. Paek, E.-J. Yoo, and I. Honma, Enhanced cyclic performance and lithium storage capacity of SnO2/graphene
nanoporous electrodes with three-dimensionally delaminated
flexible structure, Nano Lett., 9, 72 (2009).
125. L.-S. Zhang, L.-Y. Jiang, H.-J. Yan, W. D. Wang, W. Wang,
W.-G. Song, Y.-G. Guo, and L-J. Wan, Mono dispersed SnO2
nanoparticles on both sides of single layer graphene sheets as
anode materials in Li-ion batteries, J. Mater. Chem., 20, 5462
(2010).
126. D. Wang, R. Kou, D. Choi, Z. Yang, Z. Nie, J. Li, L. V. Saraf,
D. Hu, J. Zhang, G. L. Graff, J. Liu, M. A. Pope, and I. A.
Aksay, Ternary self-assembly of ordered metal oxide-graphene
nanocomposites for electrochemical energy storage, ACS Nano,
4, 1587 (2010).
127. X. Li, X. Meeng, J. Liu, D. Geng, Y. Zhang, M. N. Banis, Y.
Li, J. Yang, R. Li, X. Sun, M. Cai, and M. W. Verbrugge, Tin
oxide with controlled morphology and crystallinity by atomic
layer deposition onto graphene nanosheets for enhanced lithium
storage, Adv. Func. Mater., 22, 1647 (2012).
Downloaded by [Hanyang University] at 01:50 10 May 2013
164
I. LAHIRI AND W. CHOI
128. C. Xu, X. Wang, L. Yang, and Y. Wu, Fabrication of a graphenecuprous oxide composite, J. Solid State Chem., 182, 2486
(2009).
129. B. Wang, X.-L. Wu, C.-Y. Shu, U.-G. Guo, and C.-R. Wang, Synthesis of CuO/graphene nanocomposite as a high-performance
anode material for lithium-ion batteries, J. Mater. Chem., 20,
10661 (2010).
130. L. Q. Lu and Y. Wang, Sheet-like and fusiform CuO nanostructures grown on graphene by rapid microwave heating for high
Li-ion storage capacities, J. Mater. Chem., 21, 17916 (2011).
131. L. Ji, Z. Tan, T. R. Kuykendall, S. Aloni, S. Xun, E. Lin,
V. Battaglia, and Y. Zhang, Fe3O4 nanoparticle-intergrated
graphene sheets for high-performance half and full lithium ion
cells, Phys. Chem. Chem. Phys., 13, 7139 (2011).
132. J. Su, M. Cao, L. Ren, and C. Hu, Fe3O4-graphene nanocomposites with improved lithium storage and magnetism properties, J.
Phys. Chem. C, 115, 14469 (2011).
133. X. Zhu, Y. Zhu, S. Murali, M. D. Stoller, and R. S. Ruoff, Nanostructured reduced graphene oxide/Fe2O3 composite as a highperformance anode material for lithium ion batteries, ACS Nano,
5, 3333 (2011).
134. J. Zhou, H. Song, L. Ma, and X. Chen, Magnetite/graphene
nanosheet composites: interfacial interaction and its impact on
the durable high-rate performance in lihtium-ion batteries, RSC
Adv., 1, 782 (2011).
135. D. Wang, D. Choi, J. Li, Z. Yang, Z. Nie, R. Kou, D. Hu, C. Wang,
L. V. Saraf, J. Zhang, I. A. Aksay, and J. Liu, Self-assembled
TiO2-graphene hybrid nanostructures for enhanced Li-ion insertion, ACS Nano, 3, 907 (2009).
136. X. Rui, J. Zhu, D. Sim, C. Xu, Y. Zeng, H. H. Hng, T. M. Lim,
and Q. Yan, Reduced graphene oxide supported highly porous
v2O5 spheres as a high-power cathode material for lithium ion
batteries, Nanoscale, 3, 4752 (2011).
137. H. Wang, L.-F. Cui, Y. Yang, H. S. Casalongue, J. T. Robinson,
Y. Liang, Y. Cui, and H. Dai, Mn3O4 -graphene hybrid as a highcapacity anode material for lithium ion batteries, J. Amer. Chem.
Soc., 132, 13978 (2010).
138. S. Q. Chen and Y. Wang, Microwave-assisted synthesis of a
Co3 O4 -graphene sheet-on-sheet nanocomposite as a superior anode material for Li-ion batteries, J. Mater. Chem., 20, 9735
(2010).
139. Z.-S. Wu, W. Ren, L. Wen, L. Gao, J. Zhao, Z. Chen, G. Zhou, F.
Li, and H.-M. Cheng, Graphene anchored with Co3O4 nanoparticles as anode of lithium ion batteries with enhanced reversible
capacity and cyclic performance, ACS Nano, 4, 3187 (2010).
140. L. Shen, C. Yuan, H. Luo, X. Zhang, S. Yang, and X. Lu, In situ
synthesis of high-loading Li4Ti5O12-graphene hybrid nanostructures for high rate lithium ion batteries, Nanoscale, 3, 572 (2011).
141. Z.-S. Wu, G. Zhou, L-C. Yin, W. Ren, F. Li, and H.-M. Cheng,
Grapehene/metal oxide composite electrode materials for energy
storage, Nano Ener., 1, 107 (2012).
142. J. Xiao, X. Wang, X.-Q. Yang, S. Xun, G. Liu, P. K. Koech,
J. Liu, and J. P. Lemmon, Electrically induced high capacity
displacement reaction of PEO/MoS2/graphene nanocomposites
with lithium, Adv. Func. Mater., 21, 2840 (2011).
143. K. Chang, W. Chen, L. Ma, H. Li, H. Li, F. Huang, Z. Xu, Q.
Zhang, and J.-Y. Lee, Graphene-like MoS2/amorphous carbon
composites with high capacity and excellent stability as anode
144.
145.
146.
147.
148.
149.
150.
151.
152.
153.
154.
155.
156.
157.
158.
159.
materials for lithium ion batteries, J. Mater. Chem., 21, 6251
(2011).
Y. Cao, X. Li, I. A. Aksay, J. Lemmon, Z. Nie, Z. Yang, and J. Liu,
Sandwich-type functionalized graphene sheet-sulfur nanocomposite for rechargeable lithium batteries, Phys. Chem. Chem.
Phys., 13, 7660 (2011).
F.-Y. Su, C. You, Y.-B. He, W. Lv, W. Cui, F. Jin, B. Li, Q.H. Yang, and F. Kang, Flexible and planar graphene conductive
additives for lithium-ion batteries, J. Mater. Chem., 20, 9644
(2010).
K. Honda, M. Yoshimura, K. Kawakita, A. Fujishima, Y.
Sakamoto, K. Yasui, N. Nishio, and H. Masuda, Electrochemical
characterization of carbon nanotube/nanohoneycomb diamond
composite electrodes for a hybrid anode of Li-ion battery and
super capacitor, J. Electrochem. Soc., 151, A532 (2004).
J. Zhang, Y.-S. Hu, J.-P. Tessonnier, G. Weinberg, J. Maier, R.
Schlogl, and D. S. Su, CNFs@ CNTs: superior carbon for electrochemical energy storage, Adv. Mater., 20, 1450–1455.
J. Chen, J. Z. Wang, A. I. Minett, Y. Liu, C. Lynam, H. Liu, and
G. G. Wallace, Carbon nanotube network modified carbon fibre
paper for Li-ion batteries, Ener. Environ. Sci., 2, 393 (2009).
B. Guo, X. Wang, P. F. Fulvio, M. Chi, S. M. Mahurin, X.G. Sun, and S. Dai, Soft-templated mesoporous carbon-carbon
nanotube composites for high performance lithium-ion batteries,
Adv. Mater., 23, 4661 (2011).
S. Li, Y. Luo, W. Lv, W. Yu, S. Wu, P. Hou, Q. Yang, Q. Meng,
C. Liu, and H.-M. Cheng, Vertically aligned carbon nanotubes
grown on graphene paper as electrodes in lithium-ion batteries
and dye-sensitized solar cells, Adv. Energy Mater., 1, 486 (2011).
S. Chen, P. Chen, and Y. Wang, Carbon nanotubes grown in situ
on graphene nanosheets as superior anodes for Li-ion batteries,
Nanoscale, 3, 4323 (2011).
Z.-J. Fan, J. Yan, T. Wei, G.-Q. Ning, L.-J. Zhi, J.-C. Liu, D.-X.
Cao, G.-L. Wang, and F. Wei, Nanographene-constructed carbon
nanofibers grown on graphene sheets by chemical vapor deposition: high-performance anode materials for lithium ion batteries,
ACS Nano, 5, 2787 (2011).
K. Wang, Z. Li, Y. Wang, H. Liu, J. Chen, J. Holmes, and H.
Zhou, Carbon nanocages with nanographene shell for high-rate
lithium-ion batteries, J. Mater. Chem., 20, 9748 (2010).
Y. Zhou and Y. Wang, Sn@CNT nanostructures rooted in
graphene with high and fast Li-storage capacities, ACS Nano,
5, 8108 (2011).
S.-M. Jang, J. Miyawaki, M. Tsuji, I. Mochida, and S.-H. Yoon,
The preparation of a novel Si-CNF composite as an effective anodic material for lithium-ion batteries, Carbon, 47, 3383 (2009).
L.-F. Cui, Y. Yang, C.-M. Hsu, and Y. Cui, Carbon−silicon
core−shell nanowires as high capacity electrode for lithium ion
batteries, Nano Lett., 9, 3370 (2009).
R. Huang, X. Fan, W. Shen, and J. Zhu, Carbon-based silicon
nanowires array films for high-performance lithium-ion battery
anodes, Appl. Phys. Lett., 95, 133119 (2009).
Y.-H. Xu, G. P. Yin, Y. L. Ma, P. J. Zuo, and X. Q. Cheng,
Nanosized core/shell silicon@carbon anode material for lihtium
ion batteries with polyvinylidene fluoride as carbon source, J.
Mater. Chem., 20, 3216 (2010).
Y.-S. Hu, R. Demir-Cakan, M.-M. Titrici, J.-O. Muller,
R. Schlogl, M. Antonietti, and J. Maier, Superior storage
CARBON NANOSTRUCTURES IN LITHIUM ION BATTERIES
160.
161.
162.
163.
Downloaded by [Hanyang University] at 01:50 10 May 2013
164.
165.
166.
167.
168.
169.
170.
171.
172.
173.
174.
175.
176.
performance of a Si@SiOx/C nanocomposite as anode material
for lithium-ion batteries, Angew. Chem. Int. Ed., 47, 1645 (2008).
T. H. Hwang, Y. M. Lee, B.-S. Kong, J.-S. Seo, and J. W. Choi,
Electrospun core-shell fibers for robust silicon nanoparticle-based
lithium ion battery anodes, Nano Lett., 12, 802 (2012).
H. Wu, G. Zheng, N. Liu, T. J. Carney, Y. Yang, and Y. Cui,
Engineering empty space between Si nanoparticles for lithiumion battery anodes, Nano Lett., 12, 904 (2012).
Y. Yao, K. Huo, L. Hu, N. Liu, J. J. Cha, M. T. McDowell,
P. K. Chu, and Y. Cui, Highly conductive, mechanically robust
and electrochemically active TiC/C nanofiber scaffold for highperformance silicon anode batteries, ACS Nano, 5, 8346 (2011).
Y. Wang, H. C. Zeng, and J. Y. Lee, Highly reversible lithium
storage in porous SnO2 nanotubes with coaxially grown carbon
nanotube overlayers, Adv. Mater., 18, 645 (2006).
G. Chen, Z. Wang, and D. Xia, One-pot synthesis of carbon
nanotube@SnO2-Au coaxial nanocable for lithium-ion batteries
with high rate capability, Chem. Mater., 20, 6951 (2008).
L. B. Chen, X. M. Yin, L. Mei, C. C. Li, D. N. Lei, M. Zhang, Q. H.
Li, Z. Xu, C. M. Xu, and T. H. Wang, Mesoporous SnO2@carbon
core-shell nanostructures with superior electrochemical performance for lithium ion batteries, Nanotechnology, 23, 035402
(2012).
B. Luo, B. Wang, M. Liang, J. Ning, X. Li, and L. Zhi, Reduced
graphene oxide-mediated growth of uniform tin-core/carbonsheath coaxial nanocables with enhanced lithium ion storage
properties, Adv. Mater., 24, 1405 (2012).
P. Wu, N. Du, H. Zhang, J. Yu, Y. Qi, and D. Yang, Carboncoated SnO2 nanotubes: template-engaged synthesis and their
application in lithium-ion batteries, Nanoscale, 3, 746 (2011).
A. L. M. Reddy, M. M. Shaijumon, S. R. Gowda, and P. M.
Ajayan, Coaxial MnO2/carbon nanotube array electrodes for
high-performance lithium batteries, Nano Lett., 9, 1002 (2009).
F.-F. Cao, Y.-G. Guo, S.-F. Zheng, X.-L. Wu, L.-Y. Jiang, R.-R.
Bi, L.-J. Wan, and J. Maier, Symbiotic coaxial nanocables: facile
synthesis and an efficient and elegant morphological solution to
the lithium storage problem, Chem. Mater., 22, 1908 (2010).
H.-X. Ji, X.-L. Wu, L.-Z. Fan, C. Krien, I. Fiering, Y.-G. Guo, Y.
Mei, and O. G. Schmidt, Self-wound composite nanomembranes
as electrode materials for lithium ion batteries, Adv. Mater., 22,
4591 (2010).
M. Armand and P. Touzain, Graphite intercalation compounds as
cathode materials, Mater. Sci. Eng., 31, 319 (1977).
H.-H. Lee, C.-C. Wan, and Y.-Y. Wang, Identity and thermodynamics of lithium intercalated in graphite, J. Power Sour., 114,
285 (2003).
V. V. Viswanathan, D. Choi, D. Wang, W. Xu, S. Towne, R. E.
Williford, J.-G. Zhang, J. Liu, and Z. Yang, Effect of entropy
change in lithium intercalation in cathodes and anodes on Li-ion
battery thermal management, J. Power Sour., 195, 3720 (2010).
N. Kambe, M. S. Dresselhaus, G. Dresselhaus, S. Basu, A. R.
McGhie, and J. E. Fischer, Intercalate ordering in first stage
graphite-lithium, Mater. Sci. Eng., 40, 1 (1979).
M. Zanini, S. Basu, and J. E. Fischer, Alternate synthesis and
reflectivity spectrum of stage 1 lithium—graphite intercalation
compound, Carbon, 16, 211 (1978).
S. S. Kim, Y. Kadoma, H. Ikuta, Y. Uchimoto, and M. Wakihara,
Electrochemical performance of natural graphite by surface mod-
177.
178.
179.
180.
181.
182.
183.
184.
185.
186.
187.
188.
189.
190.
191.
165
ification using aluminum, Electrochem. Solid-State Lett., 4, A109
(2001).
I. R. M. Kottegoda, Y. Kadoma, H. Ikuta, Y. Uchimoto, and
M. Wakihara, High-rate-capable lithium-ion battery based on
surface-modified natural graphite anode and substituted spinel
cathode for hybrid electric vehicles, J. Electrochem. Soc., 152,
A1595 (2005).
I. R. M. Kottegoda, Y. Kadoma, H. Ikuta, Y. Uchimoto, and
M. Wakihara, Enhancement of rate capability in graphite anode
by surface modification with zirconia, Electrochem. Soild-State
Lett., 5, A275 (2002).
Y. S. Jung, A. S. Cavanagh, L. A. Riley, S.-H. Kang, A. C.
Dillon, M. D. Groner, S. M. George, and S.-H. Lee, Ultrathin direct atomic layer deposition on composite electrodes for
highly durable and safe Li-ion batteries, Adv. Mater., 22, 2172
(2010).
M.-S. Park, J.-H. Kim, Y.-N. Jo, S.-H. Oh, H. Kim, and Y.-J. Kim,
Incorporation of phosphorus into the surface of natural graphite
anode for lithium ion batteries, J. Mater. Chem., 21, 17960 (2011).
J. Yang, B. F. Wang, K. Wang, Y. Liu, J. Y. Xie, and Z. S.
Wen, Si/C composites for high capacity lithium storage materials,
Electrochem. Solid-State Lett., 6, A154 (2003).
Il-seok Kim, G. E. Blomgren, and P. N. Kumta, Sn/C composite
anodes for Li-ion batteries, Electrochem. Solid-State Lett., 7, A44
(2004).
C. Stangl, H. Kren, F. Uhlig, and S. Koller, High capacity
graphite–silicon composite anode material for lithium-ion batteries. B. Fuchsbichler, J. Power Sour., 196, 2889 (2011).
Y. H. Lee, K. C. Pan, Y. Y. Lin, V. Subramanian, T. Prem Kumar,
and G. T. K. Fey, Graphite with fullerene and filamentous carbon
structures formed from iron melt as a lithium-intercalating anode,
Mater. Lett., 57, 1113 (2003).
S.-H. Ng, J. Wang, D. Wexler, K. Konstantinov, Z.-P. Guo, and
H.-K. Liu, Highly reversible lithium storage in spheroidal carboncoated silicon nanocomposites as anodes for lithium-ion batteries,
Angew. Chem. Int. Ed., 45, 6896 (2006).
S. Yang, X. Feng, L. Zhi, Q. Cao, J. Maier, and K. Mullen,
Nanographene-constructed hollow carbon sphere and their favorable electroactivity with respect to lithium storage, Adv. Mater.,
22, 838 (2010).
H. Zhou, S. Zhu, M. Hibino, I. Honma, and M. Ichihara, Lithium
storage in ordered mesoporous carbon (CMK-3) with high reversible specific energy capacity and good cycling performance,
Adv. Mater., 15, 2107 (2003).
Y.-S. Hu, P. Adelhelm, B. M. Smarsly, S. Hore, M. Antonietti,
and J. Maier, Synthesis of hierarchially porous carbon monoliths with highly ordered micerostructure and their application
in rechargeable lihtium batteries with high-rate capability, Adv.
Func. Mater., 17, 1873 (2007).
N. A. Kaskhedikar, G. Cui, J. Maier, V. Fedorov, V. Makotchenko,
and A. Simon, Superfine expanded graphite with large capacity
for lithium storage, Z. Anorg. Allg. Chem., 637, 523 (2011).
B. Fang, M.-S. Kim, J. H. Kim, S. Lim, and J.-S. Yu, Ordered
multimodal porous carbon with hierarchial nanostructure for high
Li storage capacity and good performance, J. Mater. Chem., 20,
10253 (2010).
Y. Korenblit, M. Rose, E. Kockrick, L. Borchardt, A. Kvit, S.
Kaskel, and G. Yushin, High-rate electrochemical capacitors
166
192.
193.
194.
Downloaded by [Hanyang University] at 01:50 10 May 2013
195.
196.
197.
198.
I. LAHIRI AND W. CHOI
based on ordered mesoporous silicon carbide-derived carbon,
ACS Nano, 4, 1337 (2010).
Y. Liang, M. G. Schwab, L. Zhi, E. Mugnaioli, U. Kolb, X. Feng,
and K. Mullen, Direct access to metal or metal oxide nanicrystals
integrated with one-dimensional nanoporous carbons for electrochemical energy storage, J. Amer. Chem. Soc., 132, 15030 (2010).
Y. Yu, L. Gu, C. Wang, A. Dhanabalan, P. A. van Aken, and J.
Maier, Encapsulation of Sn@carbon nanoparticles in bamboolike hollow carbon nanofibers as an anode material in lithiumbased batteries, Angew. Chem. Int. Ed., 48, 6485 (2009).
Y. Yu, L. Gu, C. Zhu, P. A. van Aken, and J. Maier, Tin nanoparticles encapsulated in porous multichannel carbon microtubes:
preparation by single-nozzle electrospinning and application as
anode material for high-performance Li-based batteries, J. Amer.
Chem. Soc., 131, 15984 (2009).
A. Magasinki, P. Dixon, B. Hertzberg, A. Kvit, J. Ayala, and G.
Yushin, High-performance lithium-ion anodes using a hierarchial
bottom-up approach, Nature Mater., 9, 353 (2010).
J. Guo, X. Chen, and C. Wang, Carbon scaffold structured silicon
anodes for lithium-ion batteries. J. Mater. Chem., 20, 5035 (2010).
S.-L. Chou, J.-Z. Wang, D. Wexler, K. Konstantinov, C.
Zhong, H.-K. Liu, and S.-X. Dou, High-surface-area aplhaFe2O3/carbon nanocomposite: one-step synthesis and its highly
reversible and enhanced high-rate lithium storage properties, J.
Mater. Chem., 20, 2092 (2010).
S. W. Oh, S.-T. Myung, S.-M. Oh, K. H. Oh, K. Amine, B.
Scrosati, and Y.-K. Sun, Double carbon coating of LiFePO4 as
high rate electrode for rechargeable lithium batteries, Adv. Mater.,
22, 4842 (2010).
199. G. Wang, H. Liu, J. Liu, S. Qiao, G. M. Lu, P. Munroe, and H.
Ahn, Mesoporous LiFePO4/C nanocomposite cathode materials
for jigh power lithium ion batteries with superior performance,
Adv. Mater., 22, 4944 (2010).
200. Y. Uno, K. Tachimori, T. Tsujikawa, and T. Hirai, Effect of carbon coating on electrochemical properties of LiCoO2/nanocarbon
composites, ECS Trans., 25, 121 (2010).
201. L. Zhao, Y.-S. Hu, H. Li, Z. Wang, and L. Chen, Porous
Li4Ti5O12 coated with N-doped carbon from ionic liquids for
Li-ion batteries, Adv. Mater., 23, 1385 (2011).
202. E. Kang, Y. S. Jung, G.-H. Kim, J. Chun, U. Wiesner, A. C.
Dillon, J. K. Kim, and J. Lee, Highly improved rate capability for a lithium-ion battery nano-Li4Ti3O12 negative electrode
via carbon-based mesorporous uniform pores with a simple selfassembly method, Adv. Func. Mater., 21, 4349 (2011).
203. Y. Gogotsi and P. Simon, True performance metrics in electrochemical energy storage, Science, 334, 917 (2011).
204. R. Krishnan, T.-M. Lu, and N. Koratkar, Functionally straingraded nanoscoops for high power Li-ion battery anodes, Nano
Lett., 11, 377 (2011).
205. K. Evanoff, J. Khan, A. A. Balandin, A. Magasinski, W. J. Ready,
T. F. Fuller, and G. Yushin, Towards ultrathick battery electrodes:
aligned carbon nanotube-enabled architecture, Adv. Mater., 24,
533 (2012).
206. Arie, Arenst Andreas, Lee, Joong Kee, Structural Characteristics of Phosphorus-Doped C60 Thin Film Prepared by Radio Frequency-Plasma Assisted Thermal Evaporation Technique,
Journal of Nanoscience and Nanotechnology, 12, 1658–1661
(2012).