Preparation of OH Anion-Doped Li₆PS₅Cl Argyrodite Solid Electrolyte for Enhanced Stability in All-Solid-State Lithium Batteries

Sulfide-based solid electrolytes have garnered significant interest for their high ionic conductivity and compatibility with lithium metal anodes in all-solid-state lithium batteries (ASSLBs). Among these systems, Li6PS5Cl-type argyrodite solid electrolytes exhibit promising electrochemical properties. In this study, hydroxide (OH–) anion doping was employed to modify Li6PS5Cl solid electrolytes with the aim to enhance their structural stability and electrochemical performance. Powder X-ray diffraction measurements confirmed the successful incorporation of OH– anions in the crystal lattice. The optimized Li5.4PS4.4Cl(OH)0.6 electrolyte exhibited an ionic conductivity of 6.26 mS cm–1 at room temperature. The electrochemical analysis revealed improved stability against lithium metal, with the OH–-doped electrolyte achieving a critical current density of 0.65 mA cm–2 and sustaining stable cycling for over 300 h. An assembled ASSLB with the Li5.4PS4.4Cl(OH)0.6 electrolyte exhibited a specific capacity of 201.6 mAh g–1, 67.5% Coulombic efficiency, and excellent cycling stability with 93.0% capacity retention after 100 cycles.