Solid-state Lithium batteries: the next generation

Money is pouring into research into solid-state lithium batteries (SSBs) which promise to leapfrog existing lithium-ion battery technology.

A battery consists of three parts: a cathode, an anode, and the electrolyte. The cathode releases electrons which are then transported through the electrolyte and received by the anode. Current lithium-ion batteries use a graphite-silicon anode with a liquid electrolyte. Solid-state batteries replace the liquid with a solid electrolyte (SE), normally in a thin film — made from either an oxide, sulfide, a halide or a polymer.

Solid-State Battery

Metal-halides are gaining more attention due to their excellent compatibility toward oxide cathode materials, acceptable ionic conductivity and wide electrochemical stability. (Science Direct)

SSB Advantages

Solid-state batteries promise greater energy density, better performance at low temperatures, greater safety, faster charging, longer range, and longer battery life.

Enhanced thermal performance is expected to improve operation at low temperatures — a key weakness in cold climates. Safety is also improved by the solid electrolyte which is unlikely to leak if the battery casing is punctured — for example in a car accident — reducing the risk of a fire.

Anodes

There are still problems that have to be solved. A key stumbling block is the anode.

Lithium-metal anodes show promise but development has been plagued by dendrites which accumulate on the anode and rapidly reduce its effectiveness. Dendrites are also likely to cause a fire if they grow to the point that they pierce the barrier between the anode and the cathode.

Other developers have opted for silicon anodes but these present a different problem. Silicon is highly conductive, making it suitable for use in battery construction, but the silicon expands and contracts with each charging cycle, causing deterioration over time.

State of Progress

Toyota, one of the leading developers, has pushed back the planned introduction date for their new SSBs until 2028.

Another developer, California-based QuantumScape (NYSE:QS), seems to be making progress:

In January, Volkswagen announced successful testing on a solid-state battery developed by QuantumScape achieved more than 1,000 charging cycles and maintained 95% of its capacity. (The Guardian)

Acknowledgements

The big lithium short gets ‘dangerous’ on lower supply outlook | Bloomberg

From Mining.com:

Short bets worth billions against some of the world’s largest lithium producers are under threat as a supply glut shows signs of thinning.

UBS Group AG and Goldman Sachs Group Inc. have trimmed their 2024 supply estimates by 33% and 26%, respectively, while Morgan Stanley warned about the growing risk of lower inventories in China. The revisions come after lithium prices cratered last year as supply ran ahead of demand, with some producers cutting output.

Now, prices of the key material used to power electric vehicles are showing signs of a revival after the rout last year sent stocks spiraling and attracted short sellers. Bets against top producer Albemarle Corp. and Australian miner Pilbara Minerals Ltd. account for more than a fifth of their outstanding shares, or the equivalent to about $5 billion, according to data compiled by Bloomberg….

Long-term trends: Battery electric versus hydrogen

Scania EV

The shift towards sustainable transport systems is growing, with progress being made in electric vehicles and hydrogen fuel cells as alternatives to carbon fuels.

Heavy Transport

The major obstacle with heavy transport has been low battery range and lengthy charging times for electric vehicles (EV), leaving hydrogen fuel cells as the obvious choice.

Now, Sweden’s Scania AB, one of the world’s largest truck and bus manufacturers, is shifting emphasis to EV. Citing progress in battery technology — energy storage capacity per kg, charging times, charging cycles and economics per kg — Scania expects electrified vehicles to account for around 10 percent of their total vehicle sales volumes in Europe by 2025. And as high as 50 percent by 2030.

Hydrogen Fuel Cells

“Scania has invested in hydrogen technologies and is currently the only heavy-duty vehicle manufacturer with vehicles in operations with customers. The engineers have gained valuable insights from these early tests and efforts will continue. However, going forward the use of hydrogen for such applications will be limited since three times as much renewable electricity is needed to power a hydrogen truck compared to a battery electric truck. A great deal of energy is namely lost in the production, distribution, and conversion back to electricity.

Repair and maintenance also need to be considered. The cost for a hydrogen vehicle will be higher than for a battery electric vehicle as its systems are more complex, such as an extensive air- and cooling system. Furthermore, hydrogen is a volatile gas which requires more maintenance to ensure safety.” (Scania, January 19, 2021)

The Volkswagen AG-owned heavy vehicle manufacturer does, however, note that stationary fuel cells will still play an important part in electric charging systems. Especially in areas with abundant renewable energy, and in rural areas off the main electricity grid.

Conclusion

Electric vehicle technology has progressed much faster than hydrogen fuel cells and is the clear leader in the race for sustainable transport systems.