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Thin Film and Solid State Batteries – Is the future in R2R?
Nancy Dudney
Andrew Westover, Andrew Kercher, Sergiy Kalnaus ORNL
Erik Herbert, Michigan Technological Univ.
Valentina Lacivita, Gerd Ceder LBNL
ARPA-E IONICS program and DOE BES….
Research sponsored by:ARPA-E IONICS programDOE EERE Office of Vehicle Technologies, BMR program
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High expectations for solid-state Batteries
Toyota Roadmap for solid state battery
Bosch press release
MIT and Samsung
New superionic solid electrolyte based on bcc sulfur lattice
33
ORNL - DOE lab - solid state batteries for vehicles & grid• Battery teams work closely; different parts of ORNL organization• Always interested in finding industrial R&D partners
– https://www.ornl.gov/partnerships/industrial-partnerships
Physical Sciences
Directorate
Chemical Sciences Division
Phys Chem Materials
Nancy Dudney [email protected]
Energy & Environment Directorate
Energy & Transport Sci
Division
Roll to Roll Manufacturing
David Wood [email protected]
Computing and Comp Sci
Directorate
Computation Sci & EngDivision
Comp Energy & Energy Sci
John Turner [email protected]
44
TFB pioneered ORNL, good performance small batteries
• 1988 began research, 1996 first licensed technology • Key is electrolyte, Lipon, a lithium phosphorous oxynitride glass
e-
lo a d
55
Operation is clean. A physicist’s battery.
current collector
e-
load
Li anode
electrolyte
LiCoO2 cathode (101)
current collector
• Most electrode materials are same as bulk batteries. Others unique.• Ion diffusivity is critical; also electronic transport in electrodes
discharge chargeLi+ + e- LiLi+ + e- Li
discharge chargeLi1+xMOy LixMOy + Li+ + e-
Li1+xMOy LixMOy + Li+ + e-
66
Thin film batteries – based on intercalation compounds• See theoretical capacities• Shape reflects the crystallographic phases of cathodes• LiMn1.5Ni0.5O4 is latest and greatest, best option for Co-free
Reaction
Li0.5CoO2 LiCoO2
Mn1.5Ni0.5O4 Li Mn1.5Ni0.5O4
Mn2O4 LiMn2O4
LiMn2O4 Li2Mn2O4
V2O5 Li2V2O5
1 µAh = 3.5 mCoul
7
Exceptional cycling performance for thin film Li batteries
Li – Lipon – LixMn2O4 (550°C) Li – Lipon – LixCoO2 (800°C)
3.0
3.5
4.0
4.5
0 20 40 60 80 100
Initial ChargeD @ 10 to 500 µA/cm2
D at 0.2 to 2 mA/cm2
Cell
Pote
ntia
l (V)
Charge (µAh/cm 2)
Li - LiMn 2O4 (2µm, 550°C)
1 mA/cm2
1.52.0
0.5
10
20
30
40
50
60
70
0 1000 2000 3000 4000
Cap
acity
(µAh
/cm
2 )Cycle
600 µA/cm2100 µA/cm2
0.5 µm LiCoO2
100 µA/cm2
1.3 µm LiCoO2
4.2-3.0 V25°C
88
Excellent cycling performance: LiNi0.5Mn1.5O4 / Lipon / Li
• Same thin film cathode with solid Lipon electrolyte and liquid electrolyte• Rapid fade typical of typical composite cathodes • Conclude – fade not due to spinel cathode 1 µm LMNO films
3.5 – 5.1 V 25°C5C cycling
At 3.5V, ASR is about 200 ohm for TFB
99
Performance of thin film batteries demonstrates stability of Lipon electrolyte• High energy & power density, rapid recharge (~20 min)• High coulomb efficiency (~100%) and energy efficiency (~95%)• Long cycle life and low capacity fade (1000’s of cycles)• Stable cycling to >5V versus lithium• Self discharge negligible (store for years)• Can be solder bonded at 250°C.• Operating temperature -25° to 100°C with some degradation
Stable performance is attractive, but cost-effective manufacturing remains a challenge.
1010
10How TFBs are fabricated – Devil’s in the details!
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0.0
0.2
0.4
0.6
0.8
1.0
1.2
-0.2 0 0.2 0.4 0.6 0.8 1 1.2A
Anode current collector(dc magnetron sputtering)
Substrate Preparation
Current collector(dc magnetron sputtering)
Cathode(rf magnetron sputtering)
Electrolyte(rf magnetron sputtering)
Anode current collector(dc magnetron sputtering)
Anneal cathode(optional, 300-700°C)
Li anode(thermal evaporation)
Protective coating(parylene/Ti)
Lithium-ion anode(magnetron sputtering)
Here build on substrate.Other options to build on cathode, and build on electrolyte.
1111
Key is Lipon - sputtered dense metastable glass with N content
“Lipon” Thin Film Electrolyte Properties(Amorphous Lithium Phosphorous Oxynitride) •Typical composition Li3.3PO3.8N0.24 to Li2.9PO2.9N0.7
•Lithium conductivity 1-2 x 10-6 S/cm
•Electronic resistivity >1014 Ω cm
•Lithium ionic transference number = 1
•Stability window = 5.5 V vs. Li metal
•Stable in contact with lithium metal
•Stable to >300°C
•Near conformal, smooth surface, dense amorphous
•Elastic modulus 77 GPa
•Hardness 3.9 GPa
•Brittle, low fracture strength
Lipon electrolyte film
passivated or stable ?
Now also by ALD (Atomic Layer Deposition)University of Maryland &
PneumatiCoat Technologies
SEM cross-section of a Lipon film deposited on a polypropylene membrane.
1212
Lipon stability with Li & high V cathodes questioned?
• Abundant experimental evidence - N in Li3PO4 gives electrochem stability
• Important to understand –adding N complicates processing
• Gerd Ceder’s calculations suggest decomposition. – Li2O + Li3P + Li3N at Li anode– Li2PO2N + Li4P2O7 or just Li3PO4
at the cathode interface
• Possible passivation?
Richards, W. D.; Miara, L. J.; Wang, Y.; Kim, J. C.; Ceder, G. Interface Stability in Solid-State Batteries. Chem. Mater.2016, 28 (1), 266–273.
0 1V 2V 5V
Stability window (V vs Li metal)
13
Model for Lipon shows role of N in structure & Li mobility.
• ab initio molecular dynamics– No triply bonded N’s– N in structure as apical N and
bridging 2 PO3 groups
• Li mobility – Most mobile by a bridging N. – Least mobile at apical N.
• Models and experiment agree– .
• Pub: Valentina Lacivita and Gerd Ceder
14
Recent models and experiments reveal details of Liponstructure – not a typical glass
• Compositions with highest conductivity
• Well separate from normal glass forming compositions with PO2.5 network
• Usual N-bonding assignments do not fit with compositions
PN1.67
3
LiponDoped LiponLi3PO4, no N2
Li3PO4
LiO0.5
4 3.5
glass formingPO2.5
Li4P2O7
LiPO3
JACS 2018 V. Lacivita and A. Westover, et.al.
Experiment Models Agree:• Neutron PDF • FTIR So confident of structure
15
Recent models and experiments reveal details of Liponstructure – not a typical glass
• Compositions with highest conductivity
• Well separate from normal glass forming compositions with PO2.5 network
• Usual N-bonding assignments do not fit with compositions
PN1.67
3
LiponDoped LiponLi3PO4, no N2
Li3PO4
LiO0.5
4 3.5
glass formingPO2.5
Li4P2O7
LiPO3
JACS 2018 V. Lacivita and A. Westover, et.al.
Experiment Models Agree:• Neutron PDF • FTIR So confident of structure
16
Recent models and experiments reveal details of Liponstructure – not a typical glass
• Compositions with highest conductivity
• Well separate from normal glass forming compositions with PO2.5 network
• Usual N-bonding assignments do not fit with compositions
PN1.67
3
LiponDoped LiponLi3PO4, no N2
Li3PO4
LiO0.5
4 3.5
glass formingPO2.5
Li4P2O7
LiPO3
JACS 2018 V. Lacivita and A. Westover, et.al.
Experiment Models Agree:• Neutron PDF • FTIR So confident of structure
17
0.1
10
1
The ARPA-E IONICS challenge – stabilize Li metal anodes for high energy vehicle/grid batteries using cost-effective solid electrolytes.
Targets:• High current density
• Cycle almost all Li for deep cycle.
• Extended cycle life
• High energy per area
Albertus, (2018) Nat EnergySSB TFB with Lipon
1818
No solid electrolyte (SE) can meet all performance metrics
From IONICS arpa-e call for proposals, 2017, Paul Albertus
• Each SE material is deficient• Oxide ceramics and glass
are brittle, hard to make thin, expensive,
• Block co-polymers have lower conductivity and deform
• LGPS has poor stability with Li and is air sensitive
• What about composites of two SEs? – Interface gets in the way
of ion motion
LLZO Li7La3Zr2O12 dopedLGPS Li10GeP2S12
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Short circuits occur when Li penetrates thru solid electrolyteBlock copolymer (PS-PE)solid electrolyte in commercial batteries • Operation at 60C
• Lifetime depends on modulus, but is limited as SEEO gradually distorts, Li penetrates
Ceramic electrolyte with garnet structure, doped Li7La3Zr2O12• Superionic conductor
• Wide electrochemical stability
• Li deposits cause sudden shorts at higher current
Cheng E. J., Sharafi A. and J. Sakamoto J., Electrochimica Acta (2016).
M. Singh, ..., and M.P. Balsara , Macromolecules 40 , 4578 ( 2007 ).
Lipon does not fail by shorts
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Because Lipon does not fail by shorts, our IONICS goals are:
• New compositions “Lipon-like”, more conductive than Lipon
• Practical processing low cost
• Assembly of cells with thick cathode best energy dense
• Test hypothesis. Lipon, and Lipon-like glasses, are better suited to stabilize Li anodes, than ceramic or polymeric electrolytes.
Metastable and Glassy Ionic ConductorsA “MAGIC” solid electrolyte.
21
What is reason that Liponworks?• Composition (for passivation with Li
and conductivity)
• Microstructure (boundary free)
• Flaw free surface (glassy smooth)
• Mechanical properties (high modulus, but some plasticity)
• Electronic resistivity
Liponfilm
Are “Lipon-like” powders be scalable, less expensive?• Sufficient Li and N in glassy powder
• Reasonable conductivity as pressed compact, approaching sputtered films.
• Nice spray coat, How to sinter without crystallization?
• Rather expensive processing
22
Cost target (ARPA-E) $5 per sq.m for electrolyte– Sputter targets are expensive; assumed a more efficient design.
Deposition assumed 100nm/m.– Glassy powders formation capturing N also expensive, poor yield so far. – Scale up & larger tools will improve efficiency
powdersputtered
Membrane from:Powder throughput
2323
substrate
How do we get more energy from a solid state battery?
electrolyte
lithium
cathode
seed Li
protection Lithium
cathode
Typical battery, all a few micrometers
Optimize materials volume and weight:• Reduce inactive
components• Expand active
electrodes 10x• Balance electrode
capacitiesFor high energy
2424
New paths to Fabricate battery with very thick cathode
-0.2
0.0
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0.4
0.6
0.8
1.0
1.2
-0.2 0 0.2 0.4 0.6 0.8 1 1.2A
Anode current collector(dc magnetron sputtering)
Substrate Preparation
Current collector(dc magnetron sputtering)
Cathode(rf magnetron sputtering)
Electrolyte(rf magnetron sputtering)
Anode current collector(dc magnetron sputtering)
Anneal cathode(optional, 300-700°C)
Li anode(thermal evaporation)
Protective coating(parylene/Ti)
Lithium-ion anode(magnetron sputtering)
Cathode-supported battery• Rapid fabrication to
replace sputtering• Pure, dense cathode or
composite• Apply thin film current
collector• Maintain low R interfaces
Critical• Maintain good
interfaces, adhesion• Robust crack-free
cycling
2525 Z. Wang, … S Meng, NanoLetters 7 (2015)YI Jang, NJ Dudney, … , J ES. 149 (2002) A1442.
• Some free volume or disorder may relieve interface stress?
What is maximum cathode thickness for good energy? Consider: Li & electron motion, mechanical integrity.
Typical LiCoO2 cathode film annealed 700°C to crystallize
2626
Companies show ~15µm cathode can cycle as SS battery, LiCoO2 cathodes have particularly high Li+ and electron transport.
Sputtered cathodes Tape cast, sintered cathodes
Wei Lai and Yet-Ming Chiang, Adv Eng Mat. (2010)
Dense, 120 µm thick does not
cycle
74% dense, thick cycles when wet by
liquid electrolyte
Li+
e-
2727
Thick sintered cathodes require liquid electrolyte filled pores.• Demonstrated by Yet-Ming Chiang’s group • 100 cycles with < 5% capacity fade • Requires periodic replacement of the Li anode• No binder or carbon
Wei Lai and Yet-Ming Chiang, Adv Eng Mat. (2010)
2828
substrate
How do we reduce excess Lithium ? > 99.999% efficient• Traditionally, excess Li added
because a little is lost each cycle. SE should stop this!
electrolyte
lithium
cathode
seed Li
protection
cathode
Lithium~1/3rd cathode
thickness
Typical battery, all a few micrometers
Options• All Li can come from
cathode• Need a copper
current collector• High purity Li
• OR use a thin Li layer as the current collector• Can be very thin if
protected For high energy
2929
29Fabrication of the Li anode – Must grow on solid electrolyte
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
-0.2 0 0.2 0.4 0.6 0.8 1 1.2A
Anode current collector(dc magnetron sputtering)
Substrate Preparation
Current collector(dc magnetron sputtering)
Cathode(rf magnetron sputtering)
Electrolyte(rf magnetron sputtering)
Anode current collector(dc magnetron sputtering)
Anneal cathode(optional, 300-700°C)
Li anode(thermal evaporation)
Protective coating(parylene/Ti)
Lithium-ion anode(magnetron sputtering)
Vacuum evaporation of Li• UHV 10-9 torr• ~ 3 nm/s or more• ~15 cm throw• 1-10 µm thick onto solid
electrolyte
Active interface is buried and protected.
100 µm
tilted
Top surface will react without care to protect.
3030
Vacuum deposition conditions determine the grain size, film thickness, purity of the lithium and the interface.• Vacuum evaporation dense films, equiaxed grains. (unliked rolled Li)• Grain size, Li purity, determined by: deposition rate, base pressure, film thickness • Surface reaction/passivation determined by base pressure and Ar glove box purity• On clean solid electrolyte, Li coats entire surface with low interface resistance.
50
100150
200
250300
350
400
30 40 50 60 70 80
thin Li full
cps[110][200][211][220]cp
sdeg
Reflective Li films on glass
Coarse and fine grains of Li films No strong texture found by XRD of Li films
Plans – explore deposition conditions with new flexible deposition tool.
31
Efficient cycling demonstrated with Li-free battery• Upon charge Li from LiCoO2 cathode is plated at anode
– No Li deposited, thin film of Cu current collector– Extended cycling with little capacity loss. – Protected overlayer is essential to prevent Li loss through Cu
3μm Li
0 μm Li
0
20
40
60
80
100
120
0 200 400 600 800 1000
Cap
acity
(µAh
/cm
2 )
Cycle
no overlayer
parylene + Ti overlayer
Lipon overlayer
parylene overlayer(0.1 mA/cm2)
(1.0 mA)
(1.0)
(0.1)4.2-3.0V
25°C
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Efficient cycling demonstrated with Li-free battery• Upon charge Li from LiCoO2 cathode is plated at anode
– No Li deposited, thin film of Cu current collector– Extended cycling with little capacity loss. – Protected overlayer is essential to prevent Li loss through Cu
3μm Li
0 μm Li
0
20
40
60
80
100
120
0 200 400 600 800 1000
Cap
acity
(µAh
/cm
2 )
Cycle
no overlayer
parylene + Ti overlayer
Lipon overlayer
parylene overlayer(0.1 mA/cm2)
(1.0 mA)
(1.0)
(0.1)4.2-3.0V
25°C
33
Efficient cycling demonstrated with Li-free battery• Side by side, Li-free battery matches battery with great Li excess
– Small initial loss would go unnoticed– Cumulative loss over 1000 cycles would be obvious
– u
Solid lines = Li-freeDashed lines = Li battery
3μm Li
0 μm Li
3434
Good (indirect) evidence of low interface resistance for Lipon / Li • Low area specific resistance (ASR), probably ~10 Ω for Li/Lipon, for TFB• Buried interface is a clean interface; • Li film is dense, coats irregular surfaces
4 µm thick LiCoO2 / Lipon / Licycled 0.02 to 1 mA/cm2
3.0
3.2
3.4
3.6
3.8
4.0
4.2
0 50 100 150 200 250 300 350C
ell P
oten
tial
(V)
Charge (µAh/cm2)
4 µmcathode
Current (µA/cm2):20, 100, 200, 500,1000, and OCV
170ž•cm 2Ω·cm2ASR=170 Ω
1
10
102
103
1
10
102
103
0.001 0.1 10 103 105
Z(re
al)
(Ohm
)
Z(imaginary) (O
hm)
Frequency (Hz)
Complex impedance cell at 3.93 and 3.0V
full discharge
partial discharge
Re
Im
Re
Im
25C; 2.0µm cathode
Li/L
ipon
Lipo
n
35
Assess elastic and plastic behavior of Li thin films• As deposited then again with cycling
• Used nanoindentation housed in inert glove box.
3 Pubs by Erik Herbert J Mat Res (2018)Vol 33, issue 10
36
Assess elastic and plastic behavior of Li thin films• As deposited then again with cycling
• Used nanoindentation housed in inert glove box.
3 Pubs by Erik Herbert J Mat Res (2018)Vol 33, issue 10
Fused SilicaBerkovich indenter
loading unloading
S=dP/dh
Hardness, the mean pressure the surface can support (flow stress)
Elastic modulus
37
Mechanics tests – For Li metal thin films on glass.• Li metal is very ductile• Unusual punch-in effect. Stochastic. • Many indents mapped and analyzed for strain rate effects.
Measured High strain rate Low strain rate
38
Hardness, the mean pressure the surface can support (flow stress)
5 μm thick
18 μm thick
same nominal strain rates
Xu et al., PNAS 114 1 (2017)
Pressure supported by the Li depends on the length scale
Erik Herbert J Mat Res (2018)Vol 33, issue 10
Yield strength of bulk polycrystalline Li is 0.5MPa
39
Li is harder than you think, and will crack solid electrolytes
• In small volume, dislocation glide is not active, so Li is quite hard.
• What is the implication for electrolyte failure? Li filled cracks will certainly grow and short!.
L. Porz (2017) Adv Energy Mater
4040
Energy dense solid batteries possible at different length scales10 nm 1 µm 100 µm
Long, Rolison Dudney, Cirigliano, Dunn Sehee Lee
For good energy density:• active electrode materials must be thickest components• anode - efficient cycling of lithium metal
41
Other R&D fabrication of solid state batteries • 3D batteries - for higher interface area
– patterned electrodes, electrolyte by ALD to coat– Trilayer tape cast ceramic electrolyte (Wachsman)
• Laminated electrode and electrolyte layers *
• Milled and pressed layers * * with softer materials
* with softer materials
42
SummaryWhat are the keys for battery? Implications for processing• Different thicknesses for
maximum energy density• Requires multiple processing
methods?• Thick cathode – transport limited • Create hybrid adding liquid or
gel electrolyte• Good interfaces - conductive
and stable• Clean, 100% contact, other
factors TBD• Mechanical stability toward
breathing of cathode and plating of lithium
• Mechanics of materials, defect formation and diffusion
• Cost effective and scalable manufacturing
• Material by material, subassemblies, full battery?
• Critical flaws may cause failure • Low impurity, smooth surfaces.
