Heavily Se-Doping Influence on the Structure and Properties of Na₃SbS₄

Solid-state sodium metal batteries using sulfide-based solid electrolytes (SEs) have attracted considerable attention in terms of their high theoretical specific capacity, safety, and abounding resources. Sodium chalcogenide ionic conductors are great candidates as solid electrolytes in solid-state sodium batteries. Their high ionic conductivity of 10^-4~10^-2 S cm^-2 at room temperature, and their attractive chemical stability in the air give them great advantages. However, the synthesis method of chalcogenide solid electrolytes is required to be simple, efficient, and with a scalable approach. In this presentation, we will introduce a solvent-free and low-temperature synthesis method for heavily Se-doped Na₃SbS₄ chalcogenides with compositional control and doping contents. Se-doping in Na₃SbS₄ results in a substantial change of Sb-S bonding in Raman spectra, and enhanced ionic conductivity at room temperature. Furthermore, the electrochemical stability of heavily Se-doped Na₃SbS₄ is also demonstrated in solid-state Na||FeS₂ battery within the voltage window of 1.0-2.7 V. This technique is promoting the practical applications of chalcogenide SEs in solid-state batteries.