Li-ion batteries nearing peak, improvements possible

Lithium-ion batteries based on graphite anodes, liquid electrolytes, and cathode materials such as NMC and LFP are generally considered to be reaching their performance limits, explains IDTechEx in a new report.

“However, from cell materials to battery designs, there are still several routes that can lead to further improvements in performance and cost,” it says in releasing the report Advanced Li-ion and Beyond Lithium Batteries 2022-2032: Technologies, Players, Trends, Markets.

These include a shift from graphite to silicon.

“Promising significant improvements in energy density and performance, silicon anodes offer an exciting alternative to the incumbent graphite anodes used,” IDTechEx explains.

“While silicon material has been used in the anode in small quantities of <5 wt%, moving beyond its use as an additive has proved difficult due to its inherent volume expansion and resulting stability and cycle life issues.

“However, silicon anode technology has steadily improved over the past 10-15 years, allowing cells to use anywhere from 5-100% silicon in the anode.”

IDTechEx adds that the holy-grail battery technology for many EV manufacturers remains the solid-state battery, which can offer significant improvements to safety by replacing the flammable liquid electrolytes currently used with a solid electrolyte.

“In addition, solid electrolytes also offer the potential for using lithium metal anodes, which could push energy densities beyond 1000Wh/l. The solid-state battery market is expected to grow to over US$8 billion by 2031 with liquid electrolytes remaining an important part of the market.

“Challenges regarding the stability, cycle life, manufacturability, and even safety of solid-electrolyte systems mean the race continues between different electrolyte systems.”

Developments point to the maturing of the silicon anode market with the adoption of advanced silicon anode materials in a variety of applications becoming increasingly likely. As such, IDTechEx forecasts considerable growth in the adoption of silicon anode materials, though graphite is still expected to remain the dominant anode through to the 2030s.

Future li-ion batteries are likely to use a similar suite of cathode materials that are commercially available today, says IDTechEx.

“LNMO or the LFP related LMFP could be considered exceptions, though neither would provide improvements to energy density but offer different trade-offs between high performance and low cost.

“Li-Mn-rich NMC cathodes could provide a modest increase in energy density, but commercial development is limited and slow. Improvements to cathode materials are generally going to be incremental.

“Instead, the largest shift in cathode technology and innovation could stem from how they are synthesised. Current synthesis techniques require high temperatures over relatively long periods of time (days) whilst also using high volumes of reagent and water, leading to high manufacturing costs and environmental impact. Nano One Materials and 6K Energy (part of 6K Inc) are two companies aiming to commercialise new ways of synthesising cathode materials.”

Both promise streamlined production processes for improved throughputs, yields, and lower manufacturing costs as well as reduced environmental impacts, IDTechEx adds.

Use of new additives and electrolyte formulations can offer continued incremental improvements to liquid electrolyte systems, IDTechEx explains.

For EVs, battery pack design offers another key route to enhanced performance, says IDTechEx.

“Many automotive companies have announced batteries with cell-to-pack designs to eliminate materials associated with module housings and optimise packing efficiency, ultimately helping to improve energy density and improve battery integration into the vehicle.

“BYD advertises the possibility of improving volume utilisation by 50%, from 40% to 60%, while battery manufacturer CATL announced that its latest cell-to-pack design could achieve a 72% volume utilisation.”

IDTechEx says maximising energy density can help to mitigate the primary disadvantage of cheaper LFP cells, offering a route to cheaper, long-range batteries.

Improvements to battery management systems (BMS) can provide a route to improving multiple aspects of battery performance without the challenges associated with materials development, it says.

Ultimately, there are numerous routes to improve battery performance and cost, including various others, IDTechEx adds.

“While some developments may only offer incremental benefits, their combination will allow li-ion battery performance to continue its steady drive forward.”