Designing F-doped Li3InCl6 electrolyte with enhanced stability for all-solid-state lithium batteries in a wide voltage window

Achieving high energy densities for all-solid-state lithium batteries is restricted by the poor high voltage stability of solid electrolytes. Herein, F-doping strategy is successfully employed on Li3InCl6 to obtain enhanced voltage stability and electrode compatability towards bare LiNi0.7Mn0.2Co0.1O2 at high voltages. The optimized Li3InCl5.5F0.5 electrolyte exhibits a decreased conductivity of 1.00 mS/cm, a wider voltage window, and improved electrochemical performance in solid-state batteries when cycled at upper cut-off voltages of 4.5 and 4.8 V (vs. Li+/Li0). The generation of more stable LiInF4 phase in the cathode mixture of Li3InCl5.5F0.5-based battery ensures superior electrochemical performances compared to the Li3InCl6-based battery. The former battery exhibits a higher discharge capacity of 218.9 mAh/g and coulombic efficiency of 86.7% for the first cycle, and retains 80.0% of its original value after 100 cycles when cycled in the range of 3.0-4.5 V (vs. Li+/Li0). In contrast, the Li3InCl6-based battery exhibits lower capacities and faster degradation under the same conditions due to the formation of InCl3 phase with poor electrochemical stability. This work facilitates the advancement of high energy density solid-state battery technologies by utilizing high-voltage cathodes.