Identifying key sintering factors for high ionic conductive garnet Li6.4La3Zr2Ga0.2O12 solid electrolytes

Abstract

Garnet electrolyte Li6.4La3Zr2Ga0.2O12 (LLZGO) is one of the promising electrolyte candidates due to high Li-ion conductivity (10−4∼10−3 S/cm), superior chemical stability and wide electrochemical stable window. However, the sintering and densification process of solid-state electrolyte pellets under high temperature results in the volatilization of Li element, leading to low ionic conductivity and inaccurate control of electrolyte pellets composition. Herein, the LLZGO particle size is precisely optimized during solid-phase sintering process, exhibiting an ultrahigh ionic conductivity of 1.09 × 10−3 S/cm at room temperature. Importantly, the effects of ball milling parameters such as ball milling time, grinding aid type, and material-to-ball ratio on the particle size of electrolyte powder are revealed. This work presents a comprehensive strategy for the preparation of high conductive solid electrolytes to meet application requirements.