Session A12
Paper #81
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SOLID-STATE LITHIUM-ION BATTERIES: A BREAKTHROUGH FOR
BATTERY POWERED TECHNOLOGY
Lindsey Laurune, [email protected], 1:00 Mena Lora, Aaron Westerman, [email protected], 1:00 Mena Lora
Abstract — This paper will focus on solid state lithium ion
batteries and their use in modern electric automobiles. The
paper will investigate several solid ionic conducting
materials that replace older liquid electrolytes used in
batteries. This includes superionic conductors, thin-film
electrolytes, and glass electrolytes. As a result of different
ionic conducting materials, the many benefits of the solidstate battery will be discussed in addition to how the
batteries contribute to environmental, political, and
economic sustainability. This includes the safety, efficiency,
and increased range of temperatures they functions in. This
allows the batteries to make technology such as electric
vehicles more marketable. Finally, emerging companies and
research involving solid-state batteries will be discussed.
Key Words — Battery technology, Electric vehicles, Liquid
electrolyte, Solid electrolytes, Solid state lithium ion
batteries, sustainability
TODAY’S BATTERY TECHNOLOGY
Liquid Electrolyte Batteries
The liquid electrolyte battery is a key component to the
majority of the technology we use today. Wireless
technology such as laptops, cell phones, and electric vehicles
all utilize a liquid electrolyte battery for power.
Improvements to liquid electrolyte batteries over the years
has increased their life span, recharge time, efficiency, and
more. On the other hand, it is the liquid electrolyte itself that
limits improving batteries to their highest potential. Liquid
electrolyte batteries have limits on how compact they can be
made, and how conductive they are [2].
There are several different kinds of liquid electrolyte
used by batteries today. For example, the batteries in
automobiles utilize a lead-acid system. In a lead-acid
system, lead is combined with other metals such as calcium,
tin, or selenium to create the electrolyte. The battery is
relativity low in cost, provides electrical efficiency, high
rated performance, and comes in a variety of sizes.
However, it is prone to corrosion, which leads to a short
University of Pittsburgh Swanson School of Engineering 1
01.27.2017
cycle life, and can take several hours to recharge. Another
common battery used today is the lithium-ion electrolyte,
most commonly used in laptops. In contrast to the lead-acid,
it provides a fast recharge rate, wide range of operating
temperatures and shelf life [1]. The lithium-ion too,
however, has a short cycle life, often needing replacement
within one to three years [2].
Electric Vehicle Batteries
The electric vehicle is one example where battery
technology plays a significant role. Electric vehicles today
use a liquid electrolyte lithium-ion system, which allows for
them to be recharged at a fast rate. For example, most
models of the Tesla electric vehicles can last between two
and three hundred miles on a fully charged battery, each
recharge taking about nine hours [3]. However, range and
recharge time limitations are due to the liquid lithium-ion
electrolyte used. The flammability of the electrolyte requires
the battery to have protective packaging, which weighs
down the battery and reduces the range. Furthermore, the
liquid electrolyte regulates the flow of current in such a way
that limits the recharge time of the battery [2].
Another limitation on both electric vehicle and gasvehicle batteries is temperature. This is because as
temperature decreases, the conductivity of the electrolyte
decreases. As a result, the electrons cannot flow from the
anode to the cathode, allowing the battery to charge and
function [2].
Improvements in these characteristics of an electric
vehicle’s battery are important for the vehicles
marketability. The industry standard for electric vehicles is
two hundred miles on a charge. The longer the range of a
charge, the more marketable the electric vehicle is to a
consumer. To increase the range, qualities of the batteries
would have to be altered such as a reduction in weight,
increased energy density, or increased conductivity. But due
to the chemical properties of liquid electrolyte, these
qualities can only be altered to an extent [3].
HOW DO BATTERIES WORK?
Lindsey Laurune
Aaron Westerman
opposed to a liquid electrolyte is the solid conducting
material used in place of the liquid electrolyte, which results
in changes in the battery’s characteristics. This includes the
range in temperatures the battery functions in, life span,
charge capacity, and more. The solid electrolyte allows for
the battery cell to be more compact, reducing the necessary
separator size between cells from 20-30 microns in a liquid
electrolyte battery to 3-4 microns. The image below depicts
how the solid electrolyte leads to a reduction in battery size
through decreased spacing between cells [2].
Liquid Electrolyte Cell
A basic, liquid electrolyte battery cell consists of a
cathode, anode, and electrolyte. The anode is the negative
electrode in the cell, which releases electrons, and the
cathode is the positive electrode in the cell, which acquires
the electrons. The electrolyte is the medium between the
anode and cathode, allowing electrons to flow from the
anode to the cathode in the cell. The most common materials
used to make an anode are lithium and zinc because they
exhibit high conductivity and energy output, and are low in
cost [1]. Metal oxides such as manganese and cobalt oxide
are typically used for the cathode material due to low cost,
stability in electrolyte and functionality in voltage ranges
[1]. Finally, liquid aqueous solutions such as acids and
alkali’s are used as the electrolyte of the battery due to
strong ionic conductivity. Examples include lithium salts
such as lithium perchlorate and lithium tetrafluoroborate [1].
Another important process to most batteries today is
the recharging process. The recharging process works when
enough electrical current is applied to the cell, causing the
flow of ions from the anode to the cathode in reverse.
Different electrolytes exhibit different characteristics during
recharge, including the amount of time it takes to recharge,
and the amount of electrical current the cell can handle
without short-circuiting [4]. Figure one shows a generic
liquid electrolyte battery cell. The cathode and anode are
separated by the electrolyte, with a terminal for a load to
supply or use the charge from the battery.
FIGURE 2 [2]
Liquid lithium ion cell size versus solid-state ion cell size
Types of solid electrolyte
Research on solid-state electrolyte batteries has yet to
show a definite compound or material that out performs
another for use as a solid electrolyte. The efficiency,
performance in wide ranges of temperatures, safety, and cost
are all-important characteristics to consider. Superionic
compounds, for example, are efficient and safe, however,
their cost for use in commercial products is high. Different
solid- electrolyte materials and their performances in these
categories are discussed below.
In a study done by Yuki Kato with the Battery
Research Team at Toyota Motor Corporation, the superionic
conducting
materials
𝐿𝑖9.54 𝑆𝑖1.74 𝑃1.44 𝑆11.7 𝐶𝑙0.3
and
𝐿𝑖9.6 𝑃3 𝑆12 were tested for characteristics that dictate battery
functionality. These materials are made up of different
lithium compounds, a highly conductive metal. These highly
conductive metals would be implemented as the solid
electrolyte in solid-state ion batteries.
One of the first characteristics they tested was the
conductivity of the compounds. Conductivity is an important
characteristic to examine for any electrolyte material,
because the electrolyte’s main function in a battery is to
conduct or allow the flow of electrons from the anode to the
cathode. They found that 𝐿𝑖9.54 𝑆𝑖1.74 𝑃1.44 𝑆11.7 𝐶𝑙0.3 had the
highest conductivity of any Lithium superionic conductors
tested yet, and 𝐿𝑖9.6 𝑃3 𝑆12 with the second highest [5]. The
figure below shows the performance of all of the compounds
tested at various temperatures.
FIGURE 1 [1]
A basic liquid electrolyte battery cell
Solid Electrolyte Cell
Solid electrolyte battery cells are similar to the
structure of a liquid electrolyte battery in that they are made
up of a cathode, anode, and electrolyte. Additionally, the
ions travel through the electrolyte to get from the cathode to
anode. The difference in a solid electrolyte battery as
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Finally, the materials were put to test to see how they
would perform in a battery when exposed different currents.
Charge and discharge rates for each material were measured
at various temperatures and currant rates. They found that
the two solid superionic conducting electrolyte compounds
𝐿𝑖9.54 𝑆𝑖1.74 𝑃1.44 𝑆11.7 𝐶𝑙0.3 and 𝐿𝑖9.6 𝑃3 𝑆12 had superior rate
capabilities, especially in comparison to liquid electrolyte
Lithium-ion compounds. At 100℃, liquid electrolyte cannot
function due to chemical instability. Solid electrolyte,
however, maintained a charge density of 18 Coulombs at
this temperature. Furthermore, the solid electrolyte
maintained 75% charge capacity after 500 cycles, the typical
lifespan of liquid electrolyte batteries. Overall, they found
that at a typical room temperature of 25 ℃, the solid-state
electrolytes had a current capacity about three times higher
than the liquid electrolyte [5].
From these results, the group was able to make the
conclusion that the solid electrolyte compounds tested had
several advantages over liquid electrolyte system including
conductivity, stability, and power density. They also
concluded that as a result from these advantages, a battery
would exhibit faster charger, a longer life span, and better
performance in extreme conditions [5].
In another study done at the Oak Ridge National
Laboratory by J.B Bates and N.J Dudley, the use of solidstate thin-film lithium for a use as electrolyte was tested.
One particular battery they tested used 𝐿𝑖𝐶𝑜𝑂2 , 𝑆𝑛3 𝑁4 , and
a lithium phosphorus oxynitride for the cathode, anode, and
electrolyte, respectively. The cathodes in these batteries
were only thin films, their thickness less than fifteen
micrometers. The reason the researchers were able to
achieve such thins films is because of the solid-state
electrolyte. Liquid electrolytes are highly flammable,
requiring their cells to be spaced at distances that would
make such thin films impossible [6].
One of the main factors they looked at in the study was
the batteries performance when exposed to high
temperatures of up to 250 ℃. They were concerned with
high temperatures due to the fact that batteries in many small
devices, such as microprocessors and microcontrollers, are
exposed to such temperatures during soldering. What they
found was that the heat did not affect the batteries, an
attractive quality for many devices [6]. Additionally, they
found that the battery had a capacitance loss of only about
2% per 4000 cycles. This is in comparison to the thick-film
batteries they tested, which had a capacitance loss of .02%
per 1 cycle or 80% loss per 4000 cycles [6].
Finally, one of the most recent breakthroughs in solid
electrolyte compound materials is the glass electrolyte. In a
study done by Masahiro Tatsumisago at the Osaka
Prefecture University in Japan, different glass based
electrolyte compounds were tested for performance in
extreme temperatures and their charge and discharge
capacitance. The different compounds tested include 𝐿𝑖2 𝑆 −
𝑆𝑆𝑖2 , 𝐿𝑖2 𝑂 − 𝑁𝑏2 𝑂5 , 𝐿𝑖𝐶𝑜𝑂2 , and 𝐿𝑖𝑃𝑂𝑁.
FIGURE 3 [5]
Conductivity of various superionic compounds
The next characteristic of the superionic conducting
materials tested was the structure of the compounds. They
found that both of the materials had an LGPS crystal
structure, an important structure due to the fact that they
have unique 1-D conduction pathways. It is these 1-D
pathways that allow for the increased conductivity of the
materials, and thus the electrolyte. Additionally,
𝐿𝑖9.54 𝑆𝑖1.74 𝑃1.44 𝑆11.7 𝐶𝑙0.3 , the highest conducting material,
was found to have 3-D conduction pathways distributed
throughout its structure. They were able to conclude this by
observing the displacement of the Lithium ions in the
structure, and its nuclear density distribution. This special
structure makes it easier for ions to move through, almost
replicating the flow of ions in a liquid electrolyte [5]. The
figure below shows the nuclear density distribution of the
Lithium ions in the structure.
FIGURE 4 [5]
Nuclear distribution of lithium in superionic
compounds
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One of the first results from the study was that the
compounds exhibited increased ionic conductivity compared
to liquid electrolyte compounds. The crystal structure of
most liquid electrolyte is uniform with relatively little area
between bonds. However, the glass electrolyte’s crystal
structure is less uniform, exhibiting an, “open structure.”
This allows for the ions to pass through it with less
resistance, increasing conductivity [7]. Below, the crystal
structure of a liquid electrolyte is depicted on the left, and
the glass electrolyte’s structure on the right. It is apparent
that the liquid electrolyte’s structure is significantly more
dense and uniform, compared to the open and freer spacing
of the glass electrolyte.
electrolyte compounds were conductive at room temperature
or 25 degrees Celsius.
BENEFITS OF SWITCHING TO A SOLID
ELECTROLYTE BATTERY
Improved Efficiency
One of the main benefits of switching to a solid
electrolyte battery is the improved efficiency it could offer to
technology. To begin with, switching to a solid electrolyte
allows for a reduction in the size of the battery. In the cell of
a liquid electrolyte battery, large separators are required so
that the battery does not short circuit or become flammable.
Conventional liquid electrolyte batteries typically have
separators of twenty to thirty microns in thickness.
Switching to a solid electrolyte could reduce this thickness
to just three to four microns. This would allow for
technology such as laptops, cell phones, and electric vehicles
to be more compact [2]. Additionally, for large-scale battery
technology, size reduction can significantly decrease the
weight. This is especially important in technology such as
electric vehicles, where weight fluctuations affect the cars
performance [7].
The next way solid electrolyte batteries can improve
efficiency of our technology is through improvement on
lifespan. In the experiment done by J.B Bates and N.J
Dudley at the Oak Ridge Nation Laboratory, the thin-filmed
solid electrolyte showed only a 2% loss in capacitance over
4000 cycles, versus the liquid electrolyte, which showed an
80% loss in capacitance over 4000 cycles. For technology
such as cell phones, laptops, and electric vehicles, this
means that the battery can last longer on one charge.
Additionally, the battery itself will not need to be replaced as
frequently [6].
These qualities of the solid- state battery allow it to be
a more economically sustainable option to the consumer.
The consumer would have to pay to replace their technology
less often, and pay to recharge it frequently.
SolidEnergy, a company that specializes in thin-film
solid electrolyte battery technology, created a prototype of a
battery for use in an iPhone six that is half the size of the
current iPhone six battery. Additionally, their prototype
offers 2.0 amp-hours compared to the current iPhone 6’s 1.8
amp-hours. The company is currently working on a battery
for electric vehicles that will extend their range from two
hundred to four hundred miles [8].
FIGURE 5 [14]
Crystal structure of liquid electrolyte compared
to that of glass electrolyte
The structure of the glass electrolyte also increases the
life cycle of the battery. With the open structure and lack of
resistance in the compounds, charging and discharging can
occur in the battery more smoothly with minimal energy
loss. The results of the study showed that after five hundred
cycles of charging and discharging the battery, there was no
loss of capacity [6]. This is significant due to the fact that a
typical liquid electrolyte’s entire life span is five hundred
cycles [2]. The figure below shows the 100% efficiency
maintained by the glass electrolyte compound of 𝐿𝑖𝐶𝑜𝑂2 .
FIGURE 6 [14]
Performance of glass electrolyte
Versatility of the solid electrolyte
All three of the different types of electrolyte solids
show significant improvements upon the class liquid
electrolyte. The thin-film design falls short to the solid
superionic and glass electrolyte compounds, however, due
issues with conductivity. The thin-film design was only
found to be conductive enough at temperatures above 80
degrees Celsius, where as the superionic and glass
Solid electrolyte batteries also have an advantage over
liquid electrolyte batteries due to the variety of conditions
and situations that they can be used. The first condition solid
electrolyte batteries have advantage in temperature. For
example, a Lead-acid liquid electrolyte battery in an
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automobile typically functions in a range of temperatures
from -20℃ to 50℃. In contrast, the solid state superionic
compounds 𝐿𝑖9.54 𝑆𝑖1.74 𝑃1.44 𝑆11.7 𝐶𝑙0.3 and 𝐿𝑖9.6 𝑃3 𝑆12
functioned in temperatures from -30 ℃ 𝑡𝑜 100℃ , and the
thin film compounds 𝐿𝑖𝐶𝑜𝑂2 and 𝑆𝑛3 𝑁4 functioned in
temperatures of up to 250 ℃ [5][6]. This is due to the
increased conductivity and higher power density of the
electrolyte in a solid state [5].
Functionality over a wide range of temperatures is
important for a variety of applications. Automobile batteries
die at low temperatures, a threshold that could be expanded
through use of a solid electrolyte [7]. In addition, many
batteries in smaller devices such as microprocessors and
microcontrollers are exposed to high temperatures during the
soldering of the devices. Increasing the temperature a battery
can withstand would reduce the likely hood of hardware
malfunction in such technology [6].
Political and Economic Barriers
One major barrier of solid-state electrolyte batteries is
developing a material with low solid electrolyte-resistivity
that can compete with both current liquid electrolyte
batteries and alternative fuel sources, namely petrol. The
battery must be practical and affordable for consumers to
buy. Toyota Motor Corporation, Tokyo Institute of
Technology and High Energy Accelerator Research
Organization (KEK) in Japan have successfully designed
and conducted trials on novel, high power all-solid-state
batteries with promising results. According to experts, “these
promising results indicate that all-solid-state batteries may
soon provide a much-needed boost to applications requiring
stable, long-life energy storage” [10]. These improvements
to stability and energy storage may entice consumers to
purchase an electric vehicle with this new battery
technology.
Development of these materials is also an expensive
endeavor that must be considered. Recently, the Advanced
Research Projects Agency, an agency of the U.S.
Department of Energy, awarded a $3.4 million grant for the
purpose of creating a battery that can improve electric
vehicle driving range [11]. It should also be noted that many
of the superionic materials used in solid electrolyte
prototypes have been developed using the element
Germanium. Germanium is very expensive, so researchers
are investigating alternative superionic. Government grants
and other research investments will speed up the
development of such a material. Research into lithium ion
solid-state batteries may lead to the discovery of cheaper
electrolyte materials in the near future [11].
Improved safety
One of the most significant safety hazards associated
with liquid electrolyte batteries today is their flammability.
One way this can occur is during the charge and discharge of
the battery. Because Lithium is such a highly reactive
substance, separators are required within the battery to
separate the anode and the cathode. However, after long
periods of charging or any mechanical damage to the
battery, the separator can get damaged. This causes the
battery to discharge quickly, over heat, and short circuit.
Another way the liquid electrolyte can catch fire is
during charging, when some of the organic compounds in
the electrolyte start to break down. This creates an issue
because it increases the pressure in the battery, which cannot
be released because the battery is sealed. As the pressure
builds up, it can reach such a pressure that is bursts,
exposing the flammable electrolyte. This can lead
overheating of the cell, which can cause the technology to
catch fire [9].
Finally, the liquid electrolyte can catch fire due to a
release of oxygen within Lithium-ion cells. When the
Lithium compounds in a cell are over charged, they begin to
release oxygen, which reacts with the electrolyte. This
reaction with the electrolyte causes fibers to form on the
anode that increase the resistance within the cell. The
increased resistance leads to overheating, and flammability
of the battery [9].
A solid electrolyte improves these hazards associated
with the liquid electrolyte due to the fact that they are less
reactive than the lithium in its liquid form. In addition, the
cell is structured in such as way that the ions circulate from
the anode to cathode with minimal resistance. This reduces
the likelihood of short-circuiting and pressure within the cell
[9]. And finally, the solid electrolyte can withstand higher
temperatures [2].
Environmental Concerns
A primary concern with any new technology is its
environmental impact. The root environmental problem with
batteries is that the energy stored in a battery must come
from an energy source. Ideally, this energy source would be
clean and have minimal impact on the environment when
used to produce electricity, however if electricity is
generated primarily through burning coal then carbon
dioxide emissions from electrical vehicles are actually
greater than petroleum powered vehicles. This effect is a
result of the high carbon content of the coal used to generate
electricity that charge electric vehicles [12]. This effect can
be seen in the figure below. It is for this reason that some of
the opposition to electric vehicles arises.
There are two ways to reduce the carbon dioxide
emission from use of electric vehicles over petroleum
vehicles. These are reducing the carbon dioxide emissions
from electricity production or by reducing the carbon
dioxide emissions from battery production. To reduce the
carbon dioxide emissions from electricity production it is
necessary to change the source of electricity production from
BARRIERS AND CONCERNS
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fossil fuels to cleaner energy sources. The French electricity
distribution consists of 80% nuclear, 11% renewable and 9%
fossil fuels and waste combustion. [12]. It can be seen that
this distribution of electricity production significantly
reduces the overall carbon dioxide emissions from electric
vehicles compared to petroleum vehicles.
Another way to further reduce carbon dioxide
emissions from electric vehicles is to reduce the carbon
dioxide emissions from battery production. Solid-state
batteries would reduce the carbon dioxide emissions released
from battery production as a result of their long-life span
[11]. Reducing the carbon dioxide emissions from battery
production would reduce carbon dioxide emissions for all
electric vehicles using that battery regardless of electricity
distribution as seen in the figure below. Reduction of carbon
dioxide emissions from electricity and battery production
would reduce carbon dioxide emissions from electric
vehicles to overcome this environmental concern.
Reducing the electricity needed to charge the batteries is
important to environmental sustainability because while the
batteries may be a form of clean energy for the environment,
the source of electricity may not be [2].
Finally, solid-state ion batteries are indirectly related to
environmental sustainability through their use in electric
vehicles. Electric vehicles are more sustainable for the
environment due to the fact that they do not have any fossil
fuel emissions. Solid-state ion batteries would allow for
electric vehicles to run longer on a single charge. This makes
the electric vehicle more appealing to consumers, which
would increase the number of people who utilize an electric
vehicle, thus reducing fuel emissions [10].
Solid-state ion batteries also have political
sustainability issues involved with their use. EPA’s
definition in context of political sustainability would be
humans and their government creating conditions and
policies in which they work in harmony for present and
future generations. Solid-state ion batteries show difficulties
when it comes to political sustainability due to the fact that
research towards the batteries requires significant funding.
This is due to the fact that the batteries are made from
expensive materials such as Germanium, and they are not
yet manufacturing on a large scale to reduce the unit cost
[11].
Finally, solid-state ion batteries have economic
sustainability issues wit their use. Economic sustainability
means conditions in which humans and the cost of a product
can exist in harmony. Solid- state ion batteries present both
problems and solutions to economic sustainability.
The problem that exists with solid-state ion batteries
and economic sustainability is the fact that they are still
expensive to produce. The batteries are not manufactured on
a large scale yet to reduce costs. Additionally, many of the
solid-state batteries are made from super conducting
elements such as Germanium, which are expensive elements
[11]. The debate is whether or not the batteries
improvements upon conventional batteries are worth the
extra cost [10]. For example, solid- state batteries can last
longer on a single charge. How much more expensive of a
price is acceptable for a longer charge? In a study done by
Kevin Jones, he analyzes the cost of a solid-state ion battery
in an electric vehicle versus the driving range on a charge.
He predicts that the socially acceptable cost would be about
twenty-four cents per mile. Currently, batteries can be
produced at a cost of twenty-seven cents per mile [10]. In
order for the solid- state batteries to be economically
sustainable for electric vehicles, the cost per mile must be
reduced.
On the other hand, the batteries could create economic
sustainability. As Kevin Jones points out in his study on
solid-state batteries in electric vehicles, nations would not
have to import fuel from other nations. Additionally,
consumers would not have to pay to refuel their car. In a
more general view, any technology that utilizes a solid-state
Sustainability of solid-state ion batteries
With any new technology being researched and
designed, it is important to discuss the sustainability of the
product.
This encompasses many things including
environmental, political, and economic sustainability. And
while sustainability can encompass these three areas, it has
the same general meaning to it. According to the
Environmental Protection Agency (EPA), sustainability is,
“to create and maintain the conditions under which humans
and nature can exist in productive harmony to support
present and future generations,” [13]. Sustainability will be
discussed for environmental, political, and economic issues
with the context of this definition.
Environmental sustainability is one of the more widely
discussed topics of sustainability, especially with regards to
battery technology. The solid-state ion battery has the ability
to increase the environmental suitability of battery
technology in many ways [7]. Environmental sustainability
of battery taken in context with the EPA’s definition would
mean that the technology does not pose a threat to the
environment and the way humans interact, now or in the
future.
To start off, the solid- state lithium improves
environmental sustainability due to its longer life span. The
solid-state ion batteries, as shown in the experiment done by
J.B Bates and N.J Dudley at the Oak Ridge Nation
Laboratory, show minimal loss of capacity over a large
number of cycles [6]. A longer life span in a battery is more
sustainable because it does not need to be replaced as often,
which reduces the amount of batteries being disposed of and
into the environment [2].
Another example of how solid- state batteries improve
environmental sustainability of battery technology is through
their efficiency. Their lack of capacitance loss also reduces
the amount of times the batteries need to be charged. This
results in less electricity needed to charge the batteries.
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battery would have a longer life span, saving the consumer
money [10].
Another company heavily involved in the development
of solid-electrolyte batteries is NEI Corporation. The
company’s focus is to synthesize and manufacture materials
on a nano-scale level in order to improve the performance of
manufactured goods. The company offers materials made for
solid electrolytes, as well as cathodes to go with the
electrolyte material. The composition of the solid electrolyte
materials they offer include both oxide compounds such as
Lithium Titanium Phosphate, and sulfide compounds such as
Lithium Phosphorus Sulfide. They use these compounds due
to their high conductivity at room temperature [14].
The company has also developed different ways to
combine the cathode and solid electrolyte. The first way is a
method called composite morphology. In composite
morphology, the cathode and the electrolyte are evenly
distributed throughout the material, with the cathode and
electrolyte spaced at very small distances. Another method
used is by distributing the solid electrolyte material evenly
throughout the surface of the cathode. This method is often
favored, as the ionic conductivity of the electrolyte is better
preserved through this distribution [14].
The barrier to both companies, however, remains to be
the factor of cost. It is estimated that an all-solid electrolyte
battery for an electric vehicle would cost close to one
hundred thousand dollars. This is due to the fact that the
processes in producing the batteries on a larger scale are not
yet efficient enough, and certain compounds of the lithium
are expensive on such large scales [11].
Most recently, a potentially cheaper solid- electrolyte
solution was developed. A research team at the University of
Texas-Austin led by Professor John Goodenough and Maria
Helena Braga developed a solid glass electrolyte type battery
with an alkali-metal used for the anode. Their design
exhibits high conductivity even at temperatures as low as
negative twenty degrees Celsius They eliminated the cost
factor of solid electrolyte batteries by replacing the Lithium
with sodium. Another added benefit of the use of sodium in
their design is that the batteries are more environmentally
friendly. The team has patented their design, and is currently
working with battery makers to develop their battery to be
tested in electric vehicles [15].
WHAT’S NEXT?
On-going research and development
One of the most notable companies involved in solid
electrolyte battery production is the company Solid Energy.
In their design of batteries, they utilize a thin film lithium
anode and a combination of solid and liquid lithium
electrolyte. Their business model reduces the cost of a solid
electrolyte battery by using other partners in manufacturing
of the battery. The company develops the anode-lyte and
cathode-lyte, the two components of the electrolyte. This
consists of their compound of salts, ionic liquids, and other
chemical compounds. They then send these materials to
battery manufacturing along with a separator and cathode to
be assembled into a complete battery [8]. Solid Energy not
only focuses on solid-electrolyte batteries for use in electric
vehicles, but for use in personal electronics such as cellphones, watches, drones, and wearable technology. This
allows for increase demand and investment in the new
battery technology due to the greater market [8].
The company has already developed a working
prototype battery that functions in an iPhone six. The battery
is two Amp-hours versus the 1.8 Amp-hours currently in the
iPhone six and has an output of 400 Watt-hours per
kilogram. This is twice the energy density of the battery
currently in the iPhone six, but at only half the size. The
company developed this prototype battery within a year of
the company opening. Figure 7 below shows a size
comparison of Solid Energy’s iPhone six batteries, versus
the battery currently used [8].
CONCLUSION: A FUTURE WITH
SOLID ELECTROLYTES
Overall, solid electrolyte batteries have the potential to
improve upon our battery-powered technology in many
ways. Increased energy density, efficiency, and safety are
just a few notable benefits. These qualities will become
increasingly important as technology like electric vehicles
become more prevalent. However, the main barrier to this
technology becoming commercial is the barrier of cost. With
continued research and refinement of the processes used to
produce these batteries, production of costs could be
FIGURE 7 [8]
Solid Energy’s battery versus the iPhone six
battery size
7
Lindsey Laurune
Aaron Westerman
[13] “What is sustainability?” United States Environmental
Protection
Agency.
Accessed
3.28.2017.
https://www.epa.gov/sustainability/learn-aboutsustainability#what
[14] “Custom solid electrolyte materials.” NEI Corporation.
Accessed
3.03.2017.
http://www.neicorporation.com/products/batteries/solidstate-electrolyte/custom/
[15] “Lithium-Ion Battery Inventor Introduces New
Technology for Fast-Charging, Noncombustible Batteries.”
University of Texas- Austin. 2.28.2017. Accessed 3.03.2017.
https://news.utexas.edu/2017/02/28/goodenough-introducesnew-battery-technology
decreased. But with continued research and development of
the technology, this issue has the potential to be improved
upon, deeming solid electrolyte technology a promise
battery technology for our future.
SOURCES SECTION
[1]“Classification of Cells or Batteries” University of
Washington.
Accessed
2.19.2017.
http://depts.washington.edu/matseed/batteries/MSE/classific
ation.html
[2] Triggs, Robert. “What’s the difference between a Li-ion
and solid-state battery?” 11.8.2016. Accessed 2.21.2017.
http://www.androidauthority.com/lithium-ion-vs-solid-statebattery-726142/
[3] Lambert, Fred. “Breakdown of raw materials in Tesla’s
batteries and possible bottlenecks.” Electrek. 11.01.2016.
Accessed
3.01.2017.
https://electrek.co/2016/11/01/breakdown-raw-materialstesla-batteries-possible-bottleneck/
[4] “How does a battery work?” MIT School of Engineering.
05.01.2012.
Accessed
02.28.2017.
http://engineering.mit.edu/ask/how-does-battery-work
[5] Kato, Yuki. “High power all solid-state batteries using
sulfide superionic conductors.” Nature Energy. 3. 21. 2016.
Accessed 1.10.2017. http://tinyurl.com/h9l48n5
[6] J . Bates, N. Dudney. “Thin film lithium and lithium ion
batteries.” Elsevier. 11..1.2000. Accessed 2.28.2017.
http://www.sciencedirect.com/science/article/pii/S01672738
00003271
[7]”Solid-state battery developed at CU Boulder could
double the range of electric cars.” University of Colorado
Boulder.
9.18.2013.
Accessed
3.02.2017.
http://www.colorado.edu/today/2013/09/18/solid-statebattery-developed-cu-boulder-could-double-range-electriccars
[8]Hu, Qichao. “The renaissance of Lithum Metal:
SolidEnergy’s role in the future of lithium batteries” Solid
Energy.
Acessed
3.01.2017.
http://www.nature.com/nature/outlook/batteries/pdf/batteries
.pdf
[9] “Safety Concerns with Li-ion.” Battery University.
9.27.2016.
Accessed
3.01.2017.
http://batteryuniversity.com/learn/article/safety_concerns_wi
th_li_ion
[10] Jones, Kevin. “State of solid state batteries.” University
of Florida. Accessed 2.06.2017. http://ceramics.org/wpcontent/uploads/2011/08/energy-ss-batteries-jones.pdf
[11] “Lithium ion and beyond: the business of a battery
powered future.” SIS International Research. Accessed
2.07.2017.
https://www.sisinternational.com/publications/lithium-ionbattery-and-beyond/
[12] Espinosa, Denise. “An overview on the current
processes for the recycling of batteries.” Elsevier. 9. 3.2004.
Accessed1.10.2017. http://tinyurl.com/gvmuwb9
SOURCES REFERENCED
Knauth, Philippe. “Inorganic solid Li ion conductors: An
overview.” Elsevier. 6.25.2009. Accessed 1.9.2017.
http://www.sciencedirect.com/science/article/pii/S01672738
09001179
Wang, Yan. “Design principles for solid state lithium
superionic conductors.” 3.5.2015. Accessed 1.11.2017.
http://www.nature.com/nmat/journal/v14/n10/full/nmat4369.
html
ACKNOWLEDGMENTS
We would like to acknowledge our advisor Nick Haver
for guiding us through the process of writing the paper. He
kept us on track and provided advice on what information
was important to include. In addition, we would like to
acknowledge Bill Laurune, for introducing us to the idea of
solid electrolyte batteries.
8