Enabling ultrafast lithium-ion conductivity of Li2ZrCl6 by indium doping

Solid-state batteries with high energy density and safety are promising next-generation battery systems. However, lithium oxide and lithium sulfide electrolytes suffer low ionic conductivity and poor electrochemical stability, respectively. Lithium halide solid electrolyte shows high conductivity and good compatibility with the pristine high-voltage cathode but limited applications due to the high price of rare metal. Zr-based lithium halides with low cost and high stability possess great potential. Herein, a small amount of In3+ is introduced in Li2ZrCl6 to synthesize Li2.25Zr0.75In0.25Cl6 electrolytes with a high room temperature Li-ion conductivity of 1.08 mS/cm. Solid-state batteries using Li2.25Zr0.75In0.25Cl6/Li5.5PS4.5Cl1.5 bilayer solid electrolytes combined with Li-In anode and pristine LiNi0.7Mn0.2Co0.1O2 cathode deliver high initial discharge capacities under different cut-off voltages. This work provides an effective strategy for enhancing the conductivity of Li2ZrCl6 electrolytes, promoting their applications in solid-state batteries.