The Viability of High Specific
Energy Lithium Air Batteries
October 7, 2010
Dr. Lonnie Johnson
Excellatron Solid State LLC
Proprietary and Confidential
LITHIUM-AIR PERFORMANCE PROJECTIONS FAR
EXCEED CONVENTIONAL STATE OF THE ART CELLS
THEORETICAL VALUES OF SELECTED METAL/OXYGEN BATTERY COUPLES
Metal/O2
couple
Li/O2
Ca/O2
Zn/O2
Al/O2
Cell reaction
4Li + O2 → 2Li2O
2Ca + O2 → 2CaO
2Zn + O2 → 2ZnO
4Al + 3O2 → 2Al2O3
Open-circuit Specific energy density (Wh/kg)
voltage (V)
Including O2
Excluding O2
2.91
5200
11,140
3.12
2990
4180
1.65
1090
1350
2.73
4300
8130
LITHIUM OXYGEN COUPLE OFFERS HIGHEST SPECIFIC ENERGY
LITHIUM-AIR PERFORMANCE PROJECTIONS
Lithium Air
Specific
Energy
(Wh/kg)
Energy
Density
(Wh/l)
Specific
Power
(W/kg)
Cycle Life
2000
2000
400
500
Proprietary and Confidential
Non-aqueous metal/air battery concept
introduced by Abraham in 1996
I
LOAD
ne-
ne-
Metal anode
Mn+
O2-
M2On
Porous Cathode
Non-Aqueous
Electrolyte
O2
• Avoid water corrosion problems
• Discharge product deposits in cathode
• 2 Li + O2
Li2O2 E0 = 3.10 V
• 4 Li + O2
Li2O E0 = 2.91 V
Proprietary and Confidential
EXCELLATRON BATTERIES UNDER DEVELOPMENT
SELF CONTAINED OXYGEN IN
Battery
cells
TERMINALS
Battery
module
O2 source
O2
Oxygen
tank
•Under water, high altitude and space applications where
ambient air operation is not practical
•Uses pressurized tank or large ambient pressure oxygen
enclosure
•Rechargeable or non-rechargeable
Recharge
pump
Battery
casing
OPERATE ON OXYGEN FROM AMBIENT AIR
AIR
INTAKE
AIR
EXHAUST
Battery
casing
Air
Charge
controller
Air intake
mechanism
Battery
module
•Compact size for portable power applications
•Use desiccant to enable ambient air breathing system
•Air intake mechanism activated only as needed to minimize
desiccant pack size
•Rechargeable or non-rechargeable
Proprietary and Confidential
Oxygen
depleted
exhaust air
Charge
controller
Why the Breakthrough is Significant
Previous Efforts to Develop Li-Oxygen Technology:
Early work yielded only limited rechargeability
(3 cycles, Abraham & Jiang, 1996)
Research by at Army Research Lab yielded similar
results (3 cycles, J. Read, 2002)
Army presently focusing on non-rechargeable cells
as rechargeability was considered not viable.
No practical approach for using oxygen from ambient air
Excellatron Early Results:
•Electrolyte solvent found to be a critical element
for O2 cathodes
•Improved cycle stability, but significant capacity
fade experienced after just a few cycles
Capacity (mAh/g C)
2000
LiTFSI/C Mesh
1500
fresh solvent added
1000
500
0
0
Proprietary and Confidential
10
20
30
Cycles
40
50
Excellatron - Progress
First Significant Estension:
• Increased capacity retention by 10X over earlier
results (from over 30 to over 300 cycles)
• Cycle life extended, noisy results, electrolyte loss
still a major problem
• Identified primary solvent loss mechanism as
anode related
Further Extended Cycle Life:
• Increased round trip efficiency to 75% by the use
of electrolyte additives
• Demonstrated extended cycle life of cathode
through half-cell testing
CHARGE DISCHARGE CAPACITY 01 15 10
Capacity/mAh
Achieved Major Milestone in Cycle Life:
• Demonstrated life of over 100 cycles using a
combination of
•electrolyte formulation including additives
electrical charge protocols
• Verified specific energy goal of 1300Wh/kg using
modeling to scale actual test data.
• Defined approach for using ambient air oxygen
• Verified high discharge rate cathode design
• Developed cathode design for high rate discharge
1.5
1.4
1.3
1.2
1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
5
10
15
20
25
30
35
40
45
50
Proprietary and Confidential
55
60
65
70
Cycle no.
75
CC of LA120809.037
80
85
DC of LA120809.037
90
95
100
105
110
115
120
125
130
Breakthrough in Cycle Life Allows Excellatron to Now
Focus on More Fundamental Cell Mechanisms
Proprietary and Confidential
R&D Issues Relating to Discharge Rate
Capability
Goal is 1000Wh/kg at High Rate
Maximize Cathode Utilization
Minimize O2 Blockage by
Crust During Discharge
Minimize Electrolyte
Reduce Li2O2
Precipitation
Non-Clogging Cathode
Liquid Electrolyte
Dominates Cell Mass
Addressed by Excellatron
Cathode Structure
Li2O2 Dissolution/Transport
Focus of Excellatron/Argonne
Nat Lab Collaboration
Proprietary and Confidential
Improve Ionic and
Electronic Continuity
Focus of Excellatron/Argonne
Nat Lab Collaboration
Specific capacity of Super P in PVDF air cathodes: a)
1.0mA/cm2, b) 0.5mA/cm2, c) 0.2mA/cm2, d) 0.1mA/cm2, and
e) 0.05mA/cm2. (J. Read; Journal of The Electrochemical
Society, 149 ~9! A1190-A1195 ~2002)
Li2O2 Discharge products
forms barrier and prevents
further O2 access
Lithium Anode
SEM micrographs of PTFE air cathodes (air side of
electrode). a) Not discharged and discharged at b)
0.05mA/cm2, c) 0.2mA/cm2 and d) 1.0mA/cm2
Porous cathode
O2
Glass electrolyte
separator
Underutilized
cathode
SEM micrographs of PTFE air cathodes (center of
electrode). a) Not discharged and discharged at b)
0.05mA/cm2, c) 0.2mA/cm2 and d) 1.0mA/cm2
Proprietary and Confidential
CELL DEMONSTRATED USING THIN FILM LiPON GLASS ELECTROLYTE
BARRIER TO PROTECT LITHIUM
ANODE
TERMINAL
EDGE
SEALANT
POROUS
SUBSTRATE
DEMONSTRATED PRIMARY
LITHIUM AMBIENT AIR CELL
SINGLE BARRIER CELLS DEMONSTRATED STABLE
DISCHARGE IN AMBIENT AIR FOR OVER 3 MONTHS
LITHIUM
METAL
ELECTROLYTE
SEPARATOR
SYSTEM
LiPON GLASS
ELECTROLYTE
COATING
NANO-POROUS
SUBSTRATE
COMPOSITE
CATHODE
CARBON COMPOSITE
CATHODE
CATHODE
TERMINALS
POROUSProprietary
ALUMINIM OXIDEand
SUBSTRATE MATERIAL
Confidential
LiPON GLASS ELECTROLYTE
COATING
Develop Flexible Porous Support for Large
Area Thin Glass Barrier Electrolyte System
Results of earlier material development efforts
Edge view of porous substrate
Porous substrate surface
Glass coating on porous substrate
• Support must tolerate processing Environment
• Small pores needed to allow support of thin glass coating
• Smooth surface needed for high quality thin coating
Proprietary and Confidential
Barrier Electrolyte System using Excellatron Glass Coating
Projected Cost on Order of $1/m2
Coating appears to be of
high quality except for
imperfections associated
with dust particles
Decreased pore size to 200nm
and increased pore density
Proprietary and Confidential
Excellatron Glass Electrolyte Results
-400000
-20
LLZO T F 5cts 81020.z
LLZO T F 5cts 81020.z
-300000
-10
-200000
Z''
Z''
-100000
0
0
100000
-100000
0
100000
200000
Z'
300000
400000
10
-10
0
10
20
Z'
Lithium stablility in contact with Excellatron glass demonstrated
over several weeks in glove box
Li ion conductivity > 1E-3 S/cm from high frequency intercept
Glass appears stable in organic liquid electrolytes and water
More cost effective and higher performance alternative to LiPON
Proprietary and Confidential
Micro Batteries Using Excellatron Glass
Electrolyte
Glass coating
Next steps:
Eliminate glass film imperfections such as debris and isolated cracks
Remove LiPON from glass electrolyte separator component
Integrate Excellatron glass electrolyte into Lithium Air battery
separator system
CASTED CATHODE COATED WITH SOL GEL COVERED BY LIPON
0.01
4.5
0.009
4
0.008
3.5
0.007
0.006
2.5
0.005
2
0.004
1.5
0.003
1
0.002
0.5
0.001
0
Current/mA
3
0
0
20
40
60
80
100
120
140
160
180
200
220
240
Time/h
V of SG040910a.003
I of SG040910a.003
Li/LiPON/Excellatron Glass/LiMnOx cell:
OCV maintained for several weeks
in direct contact with lithium
Proprietary and Confidential
LITHIUM AIR CAN EXCEED ALL USABC GOALS
Lithium ion close to USABC performance goals but falls far short of cost goals
USABC MINIMUM LONG
TERM PERFORMANCE
STATE OF THE ART
LITHIUM ION @200Wh/kg
EXCELLATRON Li-Air
SMALL BATTERY
OPTION
(1,300Wh/kg)
ANODE
Graphite
Lithium Metal
CATHODE
LiCoO2
CARBON + O2
FROM AMBIENT
VOLUME (L)
300Wh/l
66.6L BATTERY (@ 600Wh/l)
166L BATTERY
WEIGHT (kg)
200Wh/kg
200kg BATTERY
76kg BATTERY
POWER (kW)
80kW (400W/kg)
80kW
49kW
CAPACITY
USABC (Wh)
40kWh
40kWh
104kWh
$100/kWh
(USABC GOAL)
$500.00/kWh
(BASED ON PRICING OF
$0.50/Wh OR $100/kg
@200Wh/kg)
$73.00/kWh
(BASED ON Li-Ion
PRICING OF
$100/kg)
200
200
468
1000cycles
1000 CYCLES FOR 200,000
MILES
$4,000
$20,000
COST
RANGE PER
CHARGE (MILES)
INTEGRATED
LIFE RANGE
COST
430 CYCLES FOR
200,000 MILES
< $7,600
($4,843 if
2,000Wh/kg)
Comparison based on 200Wh/kg Li-ION VS. 1.37kWh/kg Li-AIR at a battery cost of $90/kg