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Requirement, Design, and Challenges in Inorganic Solid State Batteries
Venkat AnandanEnergy Storage Research Department
1
2017
Ford’s Electrified Vehicle Line-up
2
HEV
Hybrid Electric
Vehicle
PHEV
Plug-in Hybrid
Electric Vehicle
BEV
Battery Electric
Vehicle
C-Max Hybrid
C-Max Energy
Fusion Hybrid
Fusion Energy
Focus Electric
Lincoln MKZ Hybrid
2017
Motivation
3
Double the mpg/Half the emission !
Energy Independence
Environment
Government Regulations
Reduce Dependence on Foreign Oil
ACCESS Number 41, Fall 2012
163
gCO2/mile
54.5 mpg
250 gCO2/mile
2017
US Electrified Vehicle Outlook
4
http://www.iea.org/media/topics/transport/GlobalEVOutlook2016FLYER.pdf
EV growth, 2010-2015
EV future outlook
http://www.iea.org/media/topics/transport/GlobalEVOutlook2016FLYER.pdf
2017
Higher specific capacity and power
density
Higher operating voltage
Higher energy efficiency
No “memory effect” means simpler
controls
OCV can be used to monitor SOC
Why Li-ion ?
5
Li-ion far exceeds the energy and power capability of Pb-acid, Ni-
Cd and Ni-MH
Saharan, V. and Nakai, K.SAE Technical Paper 2017-01-1200, 2017,
2017
Limitations in SOA Li-ion Batteries for EV Applications
6
Need a Battery technology better
than conventional Li-ion battery
technology
Vo
l. e
nerg
y d
en
sit
y
(Wh
/l)
2015 2020 2025
200
400
600
~275 Wh/L
800
Supplier
Projection
600 Wh/L
1000
Conventional Li-ion
~350 Wh/L
Beyond Li-ion ?
Samsung Galaxy Note 7
Burned Li-ion in Boeing
787
Energy Density LimitationSafety
High Packaging Cost
20177
Beyond Conventional Lithium-ion
solid state batteries could deliver high volumetric energy density than other technologies
Wh
/Kg
200
400
600
800
200 400 600 800 1000
Wh/l
2017
Advanced High Energy Lithium Battery Technologies
8
Cell Type Potential Advantages Key Challenges
Li-Air • Low cost, weight cathode (oxygen)
• High theoretical specific energy
• Similar to fuel cell technology
• Low practical energy density(~550 Wh/l).
• Low demonstrated current density and cycle life
• Complex systems requirements - on board air
scrubbing or closed O2 cycling.
• Safety issues
Li-S • Low cost cathode
• High theoretical capacity
• Sealed cell design
• Self discharge and short cycle life
• Low voltage (high cell count)
• Safety issues
solid state • No flammable electrolytes
• Compatible with existing cathode materials
• Wide temperature and voltage operating window
• Low demonstrated current density and cycle life
• Scalability uncertain
• Materials compatibility issues
Key Takeaways:
All the above technologies has to use Li metal as anode to provide high energy density
Li-air and Li-S will still have safety concerns due to the presence of liquid electrolyte
Solid state batteries offer better safety and vol energy density than other technologies
None of the technologies are ready at present for EV applications
2017
Thin film Battery Commercially available for applications including sensors, RFID tag, medical devices, and smarter cards.
Excellent cycle life (many thousands)
Very low capacity (~µAh/cm2), low current density (~ µA/cm2)
Expensive manufacturing process includes vacuum deposition tools such as sputtering, CVD, PVD.
Not Suitable for EV applications
Types of Solid State battery
9
Thin film Battery Design
EFL700A39 EnFilm from
STMicroelectronics
3.9V, 700 µAH
2017
Types of Solid State battery
10
Benefits
High energy density: Enables lithium metal and high voltage cathodes
Better safety: Eliminates flammable liquid electrolyte and may prevent dendrite formation
Thermal Stability: Stable at high temperature operations
Reduce cost: Reduction in cost and complexity may be possible at the pack level
1Assumed 20um separator, 85 um cathode thickness, 4.0 mAh/cm2 capacity loading2Assumed 50um Solid electrolyte separator, 75 um composite cathode thickness, 4.0 mAh/cm 2 capacity loading
Bulk Type Solid State Battery
NMC Cathode
Solid Electrolyte
Lithium Anode
Graphite Anode
NMC Cathode
Liquid Electrolyte
Separator
Solid State batteryConventional Li-ion
230 Wh/kg, 630 Wh/L
(Cell Level)1
230 Wh/kg, 866 Wh/L
(Cell Level)2
75 µm
20 µm
94 µm
75 µm
50 µm
40 µm
2017
Performance to Target
11
0
50
100
150
200
250
1 2 3 4 5
Sp
. E
ne
rgy d
en
sit
y)
Cathode Materials
LC
O
NC
A
NM
C
LM
O
LF
P
Cathode Materials
Sp
. E
ne
rgy D
en
sit
y
(Wh
/kg
)
0
200
400
600
800
1000
1 2 3 4 5
Vo
l. E
ner
gy d
ensi
ty
Cathode Materials
Vo
l. E
ne
rgy D
en
sit
y
(Wh
/L)
Cathode Materials
LC
O
NC
A
NM
C
LM
O
LF
P
Graphite/NMC
Li-ion Cell
Graphite/NMC
Li-ion Cell
Cathode Active
Material
Solid
Electrolyte
Lithium
Anode
A bulk type SSB design containing
existing active materials can meet
energy density target for automotive
application
Assumed 50um Solid electrolyte separator, 75 um composite cathode thickness, 4.0 mAh/cm2 capacity loading,
2x lithium metal, cathode layer contain 70% active material, 5% carbon, and 25% solid electrolyte
SSB Design
2017
Current Inorganic solid electrolytes
12
Ionic conductivity >10-4 S/cm
Negligible electronic
conductivity
Transference
Number=1
Electrochemical
window 0 to ≥ 6V
Chemical Stability
with electrodeShear Modulus
Fracture
Toughness
Relative Density
Manufacturability
( <40 µm sheets)
Lithium lanthanum Zirconium Oxide (LLZO) meets most of the requirements !
2017
Solid Electrolyte Film Processing
13
Conductivity~10-4 S/cm
Density=89%
Tape Casting Process
Solid Electrolyte (LLZO) Sheet
2017
Li Metal/Solid Electrolyte (SE) Compatibility
14
Low Li/solid electrolyte interfacial resistance with
excellent cycling could be obtained.
Cycling performance at high current density need
to be evaluated.
Li
Me
tal
LL
ZO
(S
E)
CL
i M
eta
l Low Li/LLZO
interface resistance
~44 Ω.cm2
0 10000 20000 30000
-0.2
-0.1
0
0.1
0.2
0.3
0.4
Time (Sec)
E (V
olts
)
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step01.cor
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step02.cor
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step03.cor
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step04.cor
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step05.cor
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step06.cor
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step07.cor
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step08.cor
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step09.cor
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step10.cor
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step11.cor
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step12.cor
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step13.cor
Li_LLZO_Li_58b_Cycle_Run01_Un1Ch5_Step14.cor
25µA/cm2 50µA/cm2
74µA/cm2 100µA/cm2
Shorting !
Time (s)
Po
ten
tial
(V)
With ALD-Al2O3 Coating interface
resistance ~1 Ω.cm2 and excellent cycling
was demonstratedHan et al. Nature Materials. 2016. Cycling of Li/SE/Li
Impedance of Li/SE/LiLi/SE Interface Modification
2017
Compatibility with Cathode Materials
15
Observed color change after sintering >800 °C
LLZO LLZO/LCOLLZO/LCO sintered at
900C for 5 h
Y. Ren et al. / J Materiomics xx (2016) 1-9
LLZO/LCO Compatibility
Reactivity between LLZO (SE) and cathodes
2017
A thick (>50 µm) composite cathode
structure is required.
Composite cathode should contain
active material, ionic and electronic
conducting materials.
All these materials should be
mechanically, electrochemically, and
chemically stable.
Electrode Design
16
NMC Composite
Cathode
Solid Electrolyte
Lithium Anode
NMC Active
Material
Electronic Conducting
Material
Ionic Conducting
Material
2017
Key Challenges in Solid State Battery technology
17
Electrochemistry Communications 57 (2015) 27–30
Original Solid
electrolyte Pellet
Cross section of Pellet after
short circuited
Electrochemistry Communications 57 (2015) 27–30
Li dendrite
Scalability High Rate
Lithium Dendrite Durability
SOA SSB
Need large format SSB SOA SSB performs at ~1
mA/cm2, while current Li-ion
performs >10 mA/cm2
Cycle life of SOA SSB is only about
100, while the current automotive Li-
ion battery has a cycle life of more
than 1000
2017
Conventional Li-ion battery technologies could deliver energy density ~750 Wh/l
through engineering optimization, so next generation technologies should target
beyond that.
Solid state batteries has a potential to deliver more than 900 Wh/l with better safety
than conventional Li-ion batteries.
Current state of art of the solid state batteries are not yet ready to meet the various
2020 EV requirements.
Both material and processing challenges has to be overcome to enable Solid State
batteries for EV applications.
Summary
18
