EV Batteries– challenges for power, capacity, lifetime, cost and sustainability
Daniel Brandell Ångström Advanced Battery Centre
Uppsala University
The chemical framework for EV batteries: energy density
There are plenty of room for low energy and power batteries, but not likely EVs…
How realistic are ”next generation batteries” with ”ultra-high” capacities?
• Micro-architecture
• Safety
• Thin/light Profile
• Lifetime, Cost
Portable Electronics Electric Vehicles/Utility Grids Micro-Devices
Li-ion Batteries for Energy StorageSmall-scale application
Large-scale application
• Energy Density
• Safety
• Shape Flexibility
• Lifetime, Cost
• Safety
• Power/Energy Density
• Lifetime, Cost
• Scalability
• Sustainability
Issues for the Li-ion batteries
Cu foilDelamination
Salt degradationLoss of lithium
Micro-cracking
1st cycle SEI layer formation
M0 particle deposition
TM cross-over ”Ageing”Particle contact breakdown
TM dissolution
Corrosion
E = U × Q
Challenge: PowerKinetics – primarily solid state diffusion bottlenecks
• LTO (Li4Ti5O12) anodes -> Lower voltage
• Spinel cathodes
• Nano-particles –> increased surface area
• Non-graphite anodes – fast-charging of cells
• Operation at elevated temperatures -> ageing
Challenge: Capacity
• Trade-off between power and capacity.
• Solid electrolytes? Li-metal
• Li-rich cathode materials?
• Alloying anodes and conversion materials. Stability issues, but can be mixed in to somedegree.
Alloying
Conversion
MaXb a M + b LinX
MLiwM
Alloying
Conversion
MaXb a M + b LinX
MLiwM
Cathode lower capacity than anode
Challenge: Life-time
• Solid electrolytes (polymer and ceramic)? Higher operating temp?
• Coating of electrodes? -> Power loss
• Future chemistries (Li-S, Li-air) – not highlylikely in this perspective…
Uncertainties in EV battery lifetime today
Challenge: Cost• Cathode – Co, Ni,… LiFePO4? Li2FeSiO4?
• Electrolyte – require expensive additives: Flameretardents, redox shuttles, film forming species, etc., etc… Polymer electrolytes?
• Cu current collector. Possible replacements? For Na, yes.
• Cost strongly associated with lifetime.
350 USD/ton of lithium carbonate in 20033000 USD/ton of lithium carbonate in 20086400 USD/ton of lithium carbonate in 2015
Challenge: Sustainability• Organic electrodes? Biomass eletrodes?
• Na vs Li. Li ”strategic”?
• Non-Co chemistries?
• If using Ni and Co in EVs, perhaps other cathodematerials in other devices?
• Improved recycling. Economical feasibility?
8-9 June 2017
Thank you for your attention!
Sony
Sony
1990 2005
Nano-cathodes
20151995
Ener
gy d
ensi
ty
Sony
Organic
cathodes
Future
250 Wh/kg, 800Wh/l
A123
2007 Future
Li-air
Future
Li-S
Na-ion
chemistry
Future
Li-ion batteries – past and present
??????
x 2
13
Insertion
Alloying
Conversion
homogeneous
heterogeneous
MaXb a M + b LinX
MLiwM
Mr Z
LiyMr Z
LiyMr ZInsertion
Alloying
Conversion
homogeneous
heterogeneous
MaXb a M + b LinX
MLiwM
Mr Z
LiyMr Z
LiyMr Z
Anode materials – divided by mechanistic behaviour
Graphite, Li5Ti4O12
Si, Sn, Sb
FexOy, LixNiyTiOPO4
…and Li-metal!
Electrolyte problems
Safety concerns: Undesired reactions between the battery components and liquid organic electrolyte – not strange at high or low potentials – triggered by unpredictable events such as:• Short-circuits• Local overheating• Gas formation (volatile)⇒ Exothermic reaction of the electrolyte with the electrode materials.
Thermal runaway!!
Lithium travels along poly(ethylene oxide) chains
-(CH2-CH2-O-)n
Polymer electrolytes
To increase ion conductivity:• Plasticizers
• Nanoparticles
• Change polymer: PPO, polyimides
• Modify PEO: cross-links, side-chains
• Ionic Liquids
More safe, but less mass transport