Versatility of Sb-doping enabling argyrodite electrolyte with superior moisture stability and Li metal compatibility towards practical all-solid-state Li metal batteries

Sulfide solid-state electrolytes (SSEs) are considered as one of the most promising candidates for all-solid-state Li metal batteries (ASSLMBs) on account of their high ionic conductivity and outstanding ductility. However, the poor air stability and incompatibility with Li metal seriously obstruct their application in ASSLMBs. Herein, versatile Sb-doped Li6P1-xSbxS5Cl SSEs are successfully developed to tackle these issues. The synthesized Li6P0.925Sb0.075S5Cl displays an ultrahigh ionic conductivity of 3.6 x 10-3 S cm-1 at room temperature by optimizing the concentrations of dopant. Furthermore, such electrolyte exhibits remarkable structural stability and admirable hydrolysis resistance when exposed to humid air or water, owing to the formation of SbS4 units that are thermodynamically stable to water in the Sb-doped electrolyte. Importantly, the Li6P0.925Sb0.075S5Cl SSE can induce the formation of Li-Sb alloy at the Li/SSE interface, which serves critical functions to regulate the Li+ plating/stripping behavior and decrease Li+ diffusion energy barrier across the anode interface, thus endowing an excellent long-term cyclic stability of the Li symmetric batteries (stable cycle at 0.1 mA cm-2 over 800 h) and significantly improved critical current density (1.2 mA cm-2). More encouragingly, either pristine-synthesized or air-exposed Li6P0.925Sb0.075S5Cl enables ASSLMBs with satisfying electrochemical performance at room temperature.

Automated summary

Sulfide solid-state electrolytes (SSEs) doped with Sb are developed to improve their air stability and compatibility with Li metal, making them promising candidates for all-solid-state Li metal batteries (ASSLMBs). The optimized Li6P0.925Sb0.075S5Cl electrolyte exhibits ultrahigh ionic conductivity and remarkable structural stability. It can induce the formation of Li-Sb alloy at the Li/SSE interface, regulating Li+ plating/stripping behavior and reducing Li+ diffusion energy barrier, resulting in excellent cyclic stability and improved critical current density.