Li10GeP2S12 is a phosphosulfide solid electrolyte that exhibits exceptionally high Li-ion conductivity, reaching a conductivity above 10-3 S cm-1 at room temperature, rivaling that of liquid electrolytes. Herein, a method to produce glassy-ceramic Li10GeP2S12 via a single-step utilizing high-energy ball milling was developed and systematically studied. During the high energy milling process, the precursors experience three different stages, namely, the 'Vitrification zone' where the precursors undergo homogenization and amorphization, 'Intermediary zone' where Li3PS4 and Li4GeS4 are formed, and the 'Product stage' where the desired glassy-ceramic Li10GeP2S12 is formed after 520 min of milling. At room temperature, the as-milled sample achieved a high ionic conductivity of 1.07 × 10-3 S cm-1. It was determined via quantitative phase analyses (QPA) of transmission X-ray diffraction results that the as-milled Li10GeP2S12 possessed a high degree of amorphization (44.4 wt %). To further improve the crystallinity and ionic conductivity of the Li10GeP2S12, heat treatment of the as-milled sample was carried out. The optimal heat-treated Li10GeP2S12 is almost fully crystalline and possesses a room temperature ionic conductivity of 3.27 × 10-3 S cm-1, an over 200% increase compared to the glassy-ceramic Li10GeP2S12. These findings help provide previously lacking insights into the controllable preparation of Li10GeP2S12 material.
Keywords: Li10GeP2S12; ball milling; single step synthesis; solid-state electrolyte; superionic conductor.