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

Abstract 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 H2S 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 BiBr3 as a volatile doping precursor, Bi and Br are uniformly incorporated into commercial Li6PS5Cl (LPSCl) particles through a sealed heat treatment at 500 °C. The volatilization of BiBr3 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.