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 x 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.