Li4.1P0.9Sn0.1S₄I Solid Electrolyte with Favorable Air Stability for All-Solid-State Lithium Batteries

Sulfide electrolytes are promising materials for all-solid-state lithium batteries because of their high ionic conductivity and good processability. However, the high reactivity of sulfide electrolytes with moisture leads to the structure decomposition and production of toxic H2S gas, which hinders their practical application. Herein, based on the Li3PS4 solid electrolyte, the Li4.1P0.9Sn0.1S4I solid electrolyte is synthesized through LiI and Sn codoping, which merely generates 0.098 cm3 g–1 H2S gas after air exposure due to air-stable SnS44– groups and the protection of reactant LiI·H2O. Besides, the Li/Li4.1P0.9Sn0.1S4I/Li battery exhibits a high critical current density of up to 1.1 mA cm–2 and an excellent cycling durability of 1500 h at a current density of 0.1 mA cm–2, suggesting great compatibility of the Li4.1P0.9Sn0.1S4I solid electrolyte with lithium metal. The Li4.1P0.9Sn0.1S4I-based all-solid-state lithium battery delivers an initial discharge specific capacity of 104.8 mAh g–1 and maintains a reversible capacity of 76.9 mAh g–1 after 1200 cycles at a high current density of 1C, making the Li4.1P0.9Sn0.1S4I solid electrolyte a promising candidate for all-solid-state lithium batteries.