Superior Air-Stable Li4P0.9Sb0.1S4I Solid Electrolyte for All-Solid-State Lithium Batteries

Sulfide solid electrolytes have received particular attention due to their outstanding ionic conductivity and good mechanical ductility. Nevertheless, their chemical instability toward humid air is a significant challenge that impedes the commercialization of all-solid-state batteries. Herein, air-stable Li4P0.9Sb0.1S4I solid electrolyte is synthesized by doping LiI and partially replacing P with Sb in Li3PS4 electrolyte. The Li4P0.9Sb0.1S4I solid electrolyte shows superior chemical stability under 30% relative humidity air, which is attributed to the generated LiI center dot H2O protective barrier between electrolyte and H2O molecule. In addition, benefitting from the formation of a Li4PS4I phase with Sb substitution, the Li4P0.9Sb0.1S4I electrolyte possesses high ion conductivity of 1.6 mS cm(-1). Moreover, the Li/Li4P0.9Sb0.1S4I/Li battery can stably cycle for 1500 h at 0.1 mA cm(-2), showing enhanced stability against lithium. As a result, the LiCoO2/Li4P0.9Sb0.1S4I/Li battery delivers an initial discharge capacity of 109.2 mAh g(-1) with a capacity retention of 83.6% after 500 cycles at 1C. These results demonstrate a promising Li4P0.9Sb0.1S4I solid electrolyte with high ionic conductivity, favorable stability against moisture and lithium for all-solid-state lithium batteries.