New cathode material boosts lifecycle of solid lithium batteries

Researchers from Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT) have created a new cathode material to increase the lifecycle of all-solid-state lithium batteries, thereby improving their viability for commercial applications. The researchers found that all-solid-state lithium batteries using solid electrolytes are less likely to leak and burn than conventional liquid lithium-ion batteries, which are widely used in electric vehicles, mobile phones and computers.

According to Ju Jiangwei, a PhD researcher from QIBEBT, the new cathode empowers all-solid-state lithium batteries with high conductivity, high specific discharge capacity, small volume change, high energy density and a long lifecycle compared to previous solid lithium batteries. The homogenous cathode material, which enhances the safety and performance of solid lithium batteries, has not yet been named.

Ju said the new material achieves over 1000 times the electronic and ionic conductivity of traditional battery cathode materials. It can also undergo charge and discharge cycles without conductive additives, which simplifies the battery preparation process and improves the performance of the all-solid-state lithium battery.

The new material’s 1.2% volume change during charge and discharge is more conducive to maintaining the stability of the battery structure than the traditional material, which has a volume charge of over 2.6%. The new material battery also retained 80% of its initial capacity after 5000 charge and discharge cycles.

The researchers also found that the new material battery’s energy density of up to 390 watt-hours per kilogram reportedly reflects a longer battery life 1.3 times that of the most advanced lithium-ion batteries on the market.

The new cathode material’s parent material was initially noticed in an article published by Nobel Prize winner John Bannister Goodenough in 2008. The research team found that it had the potential for excellent ionic conductivity, but due to its elemental composition, it took the team two years to synthesise this parent material.

“Contrary to our expectations, the ionic conductivity of this material is low, while the electronic conductivity is high. Therefore, we first improved the ionic conductivity by doping it with germanium, then tried to enhance the electronic conductivity by replacing sulfur with selenium, and finally obtained the new material,” Ju said.

The research team also found that replacing germanium with silicon can reduce the battery’s cost and contribute to the commercialisation of all-solid-state lithium batteries.

“We are currently preparing this material in small batches and expect to achieve large-scale production in two to three years. In terms of cost, we hope to develop a new material with less lithium in the future. If successful, the cost of sulfide solid-state lithium batteries can be reduced to 30% of that of liquid lithium batteries,” Ju said.

The researchers will also focus on the recycling of all-solid-state lithium batteries in future research. The research findings were published in the journal Nature Energy.

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