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