Na-ion batteries can be made using copper sulfide: research

While commercial lithium-ion batteries have been around since 1991 and have found applications powering everything from personal electronics to electric vehicles — and now helping to support electricity grid — around the world there has long been an effort to find cheaper, safer and more powerful alternatives.

Sodium-ion batteries have shown some promise as an alternative and sodium is significantly more available and cheaper than lithium. Sodium-ion batteries could also be safer — they can be completely drained of their charge during shipping or storage, while lithium-ion batteries need to maintain about 30% of their charge, providing energy that could ignite a fire if the batteries are damaged.

Researchers at Korea Advanced Institute of Science and Technology (KAIST) have presented a new strategy for extending sodium-ion batteries’ cyclability, using copper sulfide as the electrode material. This strategy has led to high-performance conversion reactions and is expected to advance the commercialisation of sodium-ion batteries as they emerge as an alternative to lithium-ion batteries.

Commercial lithium-ion batteries use intercalation-type materials, such as graphite, to serve as anode (negative electrode) materials that store and release lithium ions between planes of carbon atoms. But graphite anodes have not been viable for high-capacity sodium storage due to their insufficient spacing between the carbon atom layers to accommodate sodium ions.

The Korean team, led by Professor Jong Min Yuk, have confirmed a stable sodium storage mechanism using copper sulfide that is pulverised and that induces capacity recovery.

“Sodium-ion batteries employing copper sulfide can advance sodium-ion batteries, which could contribute to the development of low-cost energy storage systems and address the micro-dust issue,” said Yuk.

The team’s findings suggest that when employing copper sulfide, sodium-ion batteries will have a lifetime of more than five years with one charge per day. Copper sulfide is also composed of abundant natural materials and so has better cost-competitiveness than lithium-ion batteries, which use lithium and cobalt.

Image caption: Professor Yuk and his two PhD candidates.