Heterovalent Cation Substitution to Enhance the Ionic Conductivity of Halide Electrolytes
Xuming Luo, Xianzhang Wu, Jiayuan Xiang, Dan Cai, Min Li, Xiuli Wang, Xinhui Xia, Changdong Gu, Jiangping Tu
Abstract
Application of halide electrolytes including Li3InCl6 in all-solid-state lithium-metal batteries is still challenging due to the instability with lithium metal and limited ionic conductivity compared with liquid electrolytes and some sulfides. Here, through Zr substitution, a novel Li2.9In0.9Zr0.1Cl6 electrolyte is synthesized through the ball milling and subsequent annealing process. The ionic conductivity of Li2.9In0.9Zr0.1Cl6 (1.54 mS cm–1 at 20 °C) is nearly double that of original Li3InCl6 (0.88 mS cm–1 at 20 °C). Such conductivity enhancement is mainly attributed to the enlarged interplanar spacing and lattice volume, improved concentration of lithium-ion vacancies created by introducing higher-valence Zr4+, and the change of the preferred orientation from the (001) plane to the (131) plane. As a result, the all-solid-state lithium-metal batteries (ASSLMBs) assembled with the Li2.9In0.9Zr0.1Cl6 electrolyte also demonstrate a higher charge/discharge capacity, better cycle stability, and rate performance during cycling without an extra lithium source at the anode side.