Moisture Stability and Interfacial Compatibility of Surface Engineered Argyrodite-Type Solid Electrolytes for All-Solid-State Lithium Batteries

All-solid-state batteries (ASSBs) represent a promising alternative to traditional lithium-ion batteries by offering enhanced safety and increased energy density.Among solid electrolytes, sulfide-based materials such as Li₆PS₅Cl (LPSCl) demonstrate high ionic conductivity and facile process ability.However, their susceptibility to atmospheric moisture, which leads to the production of toxic hydrogen sulfide (H₂S) gas, presents a significant challenge.This study addresses these issues by developing and evaluating an oxygen-treated LPSCl solid electrolyte.Oxygen treatment performed under ambient conditions reduced the release of H₂S gas by 66% relative to pristine LPSCl and markedly enhanced air stability.Structural analysis disclosed lattice expansion and reorganization within the argyrodite phase, thereby enhancing pathways for lithium-ion transport.Electrochemical impedance spectroscopy (EIS) showed that the oxygen-treated LPSCl maintained a post-air-exposure ionic conductivity of 1.03 mS/cm, as opposed to 0.59 mS/cm for the untreated sample.Furthermore, the oxygen-treated electrolyte displayed enhanced lithium metal stability, achieving prolonged DC cycle performance at 0.1 mA/cm² and a discharge specific capacity of 162.2 mAh/g at a 0.1 C-rate.These findings underscore the potential of controlled oxygen exposure to improve moisture stability, ionic conductivity, and electrochemical performance, offering a scalable approach for integrating sulfide-based electrolytes into next-generation ASSBs.