Fast Li+-conducting Zr4+-based oxychloride electrolyte with good thermal and solvent stability

Li2ZrCl6 with a trigonal structure is a low-cost Li+-conducting chloride electrolyte, which is stable at high voltages up to 4.2 V and is compatible with high-voltage cathodes. However, its relatively low room-temperature ionic conductivity, poor stability in different solvents and at high temperatures limit its application for next-generation all-solid-state batteries. Herein, we prepared new oxychloride electrolytes with different molar ratios of Li2O, ZrCl4, and LiCl, replacing Cl− with O2− anion to optimize the electrolyte performance. The results showed that increasing the Li2O content reduced the crystallization degree of trigonal Li2ZrCl6 and induced a monoclinic structure in the prepared oxychloride electrolyte. The oxychloride with the general formula Li2.22Zr1.11Cl5.33O0.67 had a high room-temperature ionic conductivity above 10−3 S cm−1. Moreover, introducing Li2O considerably increased the thermal and solvent stability of the electrolyte. Good ionic conductivity and stability of the electrolyte enable the stable cycling of all-solid-state Li-In/LiCoO2 batteries.