Enhancing Moisture Stability and Structural Integrity of Argyrodite Li ₆ PS ₅ Cl Solid Electrolytes via Porous Silica Incorporation

Porous silica particles are incorporated into argyrodite-type Li₆PS₅Cl (LPSCl) solid electrolytes to mitigate structural degradation and ionic conductivity loss under moisture exposure. Because of its high pore volume and large surface area, porous silica efficiently captures H₂O molecules before reacting with LPSCl, thereby suppressing H₂S evolution and moisture-induced decomposition. Moreover, the porous silica enhances the mechanical integrity of the composite cathode. While the intrinsic softness of LPSCl results in stress localization to the cathode active materials and nonuniform densification during electrode compaction, the relatively higher stiffness of porous silica facilitates pressure redistribution, promoting uniform densification and improving interparticle contact. Structural and electrochemical analyses confirm that the porous silica-incorporated LPSCl maintains its ionic conductivity and moisture stability, even at 50% relative humidity. Furthermore, all-solid-state batteries (ASSBs) utilizing a silica-embedded LPSCl composite electrolyte exhibit superior cycling performance. This dual-function strategy provides a practical and scalable route for simultaneously improving the moisture and structural stabilities of sulfide electrolytes, thereby advancing the development of high-performance ASSBs suitable for ambient processing.