A new sodium-ion conductor developed by an international research team offers scope for enhancing the stability of solid-state sodium-ion batteries. Incorporated into higher-voltage oxide cathodes, this solid electrolyte could improve the efficiency and lifespan of these batteries.

Candidate materials for the new conductor were screened by use of a machine learning model and led to the selection of halide sodium conductors composed of sodium, yttrium, zirconium and chloride. Characterization of this NYZC material demonstrated to be electrochemically stable and chemically compatible with the oxide cathodes used in higher voltage sodium-ion batteries.

The presence of zirconium increases the conduction of sodium ions by expanding the volume of the cell The NYZC structure, with the orange/brown structures surrounding the zirconium (green) denoting rotation. Source: Shyue Ping Ong et al.battery unit. Another performance benefit is imparted by the combination of zirconium and chloride ions, which maintain a rotating motion, generating more conduction pathways for sodium ions. The halide material is also more stable than materials currently used in solid-state sodium batteries.

A proof of concept battery built with the new material lasted over 1,000 cycles and retained 89% of its capacity, demonstrating performance superior to that of other available solid-state sodium batteries. Research will continue to strengthen battery power density and to scale up the conductor material manufacturing process.

A paper on the study conducted by scientists from the University of California San Diego, the University of California Santa Barbara, Stony Brook University, TCG Center for Research and Education in Science and Technology (India), Shell International Exploration & Production Inc and Shell Global Solutions International BV (the Netherlands) appears in Nature Communications.