Moisture-Tolerant Sulfide Solid Electrolytes Enabled by Gas-Phase Surface Engineering

Sulfide solid electrolytes are pivotal for the advancement of all-solid-state lithium batteries due to their superior ionic conductivity and mechanical ductility. However, their commercialization is severely hindered by inherent moisture sensitivity, which leads to structural degradation and hazardous H 2 S gas generation. Addressing this challenge without compromising ionic conductivity remains a significant hurdle. Herein, we develop a gas-phase surface-engineering strategy for in situ doping that simultaneously enhances the moisture tolerance and electrochemical performance of commercial solid-state electrolytes. Using low-melting-point BiBr 3 as a volatile doping precursor, Bi and Br are uniformly incorporated into commercial Li 6 PS 5 Cl (LPSCl) particles through a sealed heat treatment at 500 ° C. The volatilization of BiBr 3 promotes homogeneous gas–solid contact and reaction, yielding Bi/Br- co -doped LPSCl with substantially improved resistance to moisture-induced degradation. All-solid-state lithium batteries (ASSLBs) employing this electrolyte exhibit markedly improved rate capability and more stable cycling performance compared to ASSLBs using pristine LPSCl. This work provides a facile and effective pathway to simultaneously achieve high moisture tolerance and excellent electrochemical performance in sulfide solid electrolytes.