Argyrodite Solid Electrolyte with a Stable Interface and Superior Dendrite Suppression Capability Realized by ZnO Co-Doping.

Despite the high ionic conductivity and good machinability, the application of sulfide solid electrolytes (SEs) is severely limited by the poor compatibility of oxide cathodes with Li metals. Herein, a ZnO co-doping strategy is proposed to enhance the chemical and electrochemical performance of sulfide SEs. Given the synergistic effect by incorporation of ZnO, the argyrodite electrolyte achieves superior interfacial stability and Li dendrite suppression capability. By in-depth ex situ analyses, the enhancement is ascribed to LiZn and Li3OBr formed in the argyrodite/Li interface and a reduced electronic conductivity arising from the ZnO doping. In addition, O doping improves the air stability for argyrodite without degrading the ionic conductivity because of the compensation by Zn doping. Hence, all-solid-state batteries with ZnO-doped electrolytes achieve higher initial Coulombic efficiency and a larger specific capacity than those of the ZnO-free electrolyte. ZnO-doped sulfide SEs are promising to develop all-solid-state Li-metal batteries.