Revitalizing Sulfide Solid Electrolytes for All-Solid-State Batteries: Dry-Air Exposure and Microwave-Driven Regeneration

Abstract

Processing sulfide solid electrolytes under dry-air conditions at which certain levels of moisture are unavoidable poses challenges in the practical mass production of all-solid-state batteries (ASSBs). Herein, a facile microwave-driven regeneration method is presented for Li6PS5Cl (LPSCl) degraded by dry-air exposure, particularly after solvent treatment. While dry-air exposure with a dew point of -40 degrees C for 6 h degrades the Li+ conductivity of wet-processed LPSCl from 3.33 to 2.55 mS cm-1 at 30 degrees C, microwave irradiation at 800 W for only 10 min restores 98.3% of the Li+ conductivity of pristine LPSCl (3.26 mS cm-1) and maintains its electron-insulating property. By contrast, conventional furnace heat treatment recovers only 83.8% of Li+ conductivity and causes severe carbonization. Comprehensive analyses reveal that microwave heating selectively eliminates hydration layers and carbonates without inducing structural alterations or byproduct evolution. Electrochemical tests demonstrate that the microwave-regenerated LPSCl achieves performance nearly identical to the pristine LPSCl in LiNi0.7Co0.15Mn0.15O2||(Li-In) cells. Its practical applicability is further validated in LiNi0.7Co0.15Mn0.15O2||(Ag-C) pouch-type ASSBs. This rapid, scalable, and energy-efficient regeneration method can ensure consistent sulfide solid electrolyte performance, regardless of storage or transport history, enabling reliable large-scale manufacturing of ASSBs.