A sodium-ion sulfide solid electrolyte with unprecedented conductivity at room temperature

摘要

Solid electrolytes are key materials to enable solid-state rechargeable batteries, a promising technology that could address the safety and energy density issues. Here, we report a sulfide sodium-ion conductor, Nasub2.88/subSbsub0.88/subWsub0.12/subSsub4/sub, with conductivity superior to that of the benchmark electrolyte, Lisub10/subGePsub2/subSsub12/sub. Partial substitution of antimony in Nasub3/subSbSsub4/sub with tungsten introduces sodium vacancies and tetragonal to cubic phase transition, giving rise to the highest room-temperature conductivity of 32?mS?cmsup-1/sup for a sintered body, Nasub2.88/subSbsub0.88/subWsub0.12/subSsub4/sub. Moreover, this sulfide possesses additional advantages including stability against humid atmosphere and densification at much lower sintering temperatures than those (1000?°C) of typical oxide sodium-ion conductors. The discovery of the fast sodium-ion conductors boosts the ongoing research for solid-state rechargeable battery technology with high safety, cost-effectiveness, large energy and power densities.