High-Conductivity and Moisture-Tolerant Sulfide Electrolyte Enabled by Bifunctional Coating for Practical All-Solid-State Lithium Batteries.

The pursuit of safer and higher-energy-density batteries has driven the advancement of all-solid-state lithium batteries (ASSLBs). Among various material systems, sulfide solid-state electrolytes (SEs) stand out as highly promising candidates owing to their exceptional ionic conductivity. Nevertheless, their extreme sensitivity to moisture results in the release of toxic H2S and rapid structural degradation, which severely impedes their scalable manufacturing under ambient conditions. A bifunctional (3-mercaptopropyl)trimethoxysilane (MPTMS) coating strategy is herein presented to shield Li5.5PS4.5Cl0.8Br0.7 (LPSCBr) from moisture-induced degradation. The MPTMS layer forms a hydrophobic barrier of approximately 10 nm, which reduces H2S emission by 93.0% after 35 min of exposure to 30% relative humidity, while maintaining 83.1% of the initial ionic conductivity (10.8 mS cm-1). This approach tackles the core challenge associated with sulfide solid-state electrolytes: the realization of compatibility with controlled ambient air without sacrificing critical electrochemical properties. The modified electrolyte maintains a high ionic conductivity (> 5.7 mS cm-1) even after 10 h of air exposure. When applied in all-solid-state cells paired with LiNi0.83Co0.11Mn0.06O2 cathodes, it exhibits remarkable electrochemical performance, delivering a capacity retention of 84.6% after 1000 cycles. By enabling moisture-tolerant processing, MPTMS-modified LPSCBr SEs lay a solid foundation for the scalable, high-performance, and cost-effective production of ASSLBs.