Amorphous Li₂O–LiI Solid Electrolytes Compatible to Li Metal

Abstract

Development of oxide solid electrolytes for all-solid-state batteries is attracting increasing attention. In this study, amorphous Li₂O–LiI materials are prepared via a mechanochemical process to achieve high lithium ionic conductivity and good compatibility to lithium metal. Amorphous 66.7Li₂O·33.3LiI (mol%) electrolyte shows a high ionic conductivity of 3.1 × 10⁻⁵ S cm⁻¹ at 25 °C with a relative density of 96 %. An all-solid-state Li symmetric cell (Li/66.7Li₂O·33.3LiI/Li) operates without an increase in overvoltage. A simple combination of lithium oxide and lithium iodide exhibits high ionic conductivity, ductility, and stability to lithium metal.