Synthesis and electrochemical performance of antiperovskite-like Li3SI solid electrolyte

Abstract Lithium-rich antiperovskite-type (LiRAP) solid electrolytes have received a great deal of attention due to their high mobile ion occupancy rate and narrow activation barrier. Oxide-based LiRAPs are widely studied. However, almost no reports are available on the electrochemical nature of sulfide-based LiRAPs. Here, we prepared the first antiperovskite-like Li3SI – solid solution type solid electrolyte and studied its electrochemical properties. The crystalline nature of the electrolyte was evaluated by powder X-ray diffraction. Electrochemical impedance spectroscopy showed that the Li3SI solid electrolyte exhibited an ionic conductivity of 2.2 × 10−5 S cm−1 at room temperature. The electrochemical stability of the electrolyte was studied with cyclic voltammetry and DC cycle tests, which showed that the proposed electrolyte was stable up to 10 V and >100 h, respectively. An assembled all-solid-state lithium battery using the Li3SI solid electrolyte exhibited an initial discharge capacity of 96.8 mAh g−1 at a current density of 3 mA g−1.