Lithium-ion batteries are the global source of power for smartphones, electric vehicles (EVs), robots and grid storage. These batteries replaced older chemistries that could not compete on lifespan or weight.

But lithium-ion batteries aren’t perfect. Far from it. Because these batteries are prone to overheating and irreversible capacity loss, companies are focused on improving them for longer lifespans.

Asahi Kasei believes it may have an answer. The company has developed a pre-doping technology for high-voltage lithium-ion batteries with silicon-based anodes that use lithium carbonate to serve as an additional lithium source at lower voltages to reduce this permanent capacity loss.

This is especially important with the growing adoption of EVs and humanoid robots demanding more from their lithium-ion batteries with higher energy densities.

Asahi Kasei pointed to previous developments that focused on partially replacing graphite with silicon-based materials in the anode or those focused on increasing the operating voltage of the cathode materials as insufficient. This is due to silicon-based anodes suffering irreversible capacity loss during the initial charge/discharge cycle, which limits the battery’s lifespan and total energy density.

Asahi Kasei’s pre-doping development could boost total energy density leading to longer lasting lithium-ion batteries. Source: Asahi Kasei

The answers previously were to add greater amounts of cathode active material, but this results in higher materials use and therefore higher costs.

Asahi Kasei said lithium carbonate as an alternative in lithium-ion batteries is a challenge because the existing method of using the material has a decomposition voltage far above the nominal operating voltage of lithium-ion batteries.

The method developed by Asahi Kasei uses special additives in the electrolyte to promote the decomposition of lithium carbonate at typical cell voltages of standard lithium-ion batteries. This allows the material to be pre-added to the cathode as a lithium sacrifice during the initial charge.

Test results

The company claims the use of the low-cost material improves energy density. Asahi Kasei ran internal tests with a nickel-manganese-cobalt cell having an anode of 90% graphite and 10% silicon monoxide (SiO), which showed a 10% increase in energy density.

It also improved the cycle life at a low cost per watt-hour.

Without significant modifications to existing battery manufacturing lines, the company claims the method could be applied and could be broadly applicable across a range of cathode and anode material systems.

The next steps are to license the technology and create a collaborative framework through 2027.