Asahi Kasei reports 10% energy-density gain in internal battery test

On the first charge of a silicon-rich battery, some lithium disappears before the cell has begun its useful working life. Asahi Kasei says it has found a way to put some of it back: in an internal test, its pre-doping method delivered a 10% increase in energy density in an NMC lithium-ion cell using an anode made from 90% graphite and 10% silicon monoxide.

The trick starts with lithium carbonate, a relatively inexpensive material already used in battery manufacturing. Normally, it decomposes at a voltage far above the operating range of a standard lithium-ion battery. Asahi Kasei says special additives in the electrolyte change those conditions, allowing lithium carbonate placed in the cathode to break down during the initial charge and supply extra lithium.

That extra supply targets silicon's main limitation. Silicon can store more lithium than graphite, but it consumes a significant amount during the first charge, causing permanent capacity loss. By compensating for that loss, the process could leave more lithium available for subsequent charging and discharging, while reducing the need for additional cathode active material.

And so what, concretely? Battery manufacturers could test the approach without building an entirely new production system: Asahi Kasei says it can be applied to existing lines without significant modifications and across different cathode and anode combinations. For electric vehicles and other applications seeking higher energy density, that means a possible performance improvement through a materials and electrolyte change rather than a complete cell redesign.

The distance from test cell to product is still substantial. These figures come from Asahi Kasei's internal testing, and no larger-scale or independent reproduction is reported here. The company plans global proof-of-concept evaluations with customers and intends to license the technology through collaboration models tailored to each customer's development stage.