Solvent-Free and Long-Cycling Garnet-Based Lithium-Metal Batteries

Solid-state batteries using ceramic solid electrolytes promise to deliver enhanced energy density and intrinsic safety. However, the challenge of integrating solid electrolytes with electrode materials limits the electrochemical performance. Herein, we report a solvent-free ceramic-based lithium-metal battery with good cycling stability at a wide temperature range from 45 to 100 degrees C, enabled by an inorganic ternary salt of low eutectic point. By using a garnet electrolyte with molten salts at the electrolyte|cathode interface, the Li||LiFePO4 cells perform a long cycling with capacity retention of 81.4% after 1000 cycles at 1 C. High-voltage LiFe0.4Mn0.6PO4 cathodes also deliver good electrochemical performance. Specifically, commercial electrode pieces with high area capacities can be adopted directly in the quasi-solid-state lithium-metal batteries. These stable performances are ascribable to the low melting point, high ionic conductivity and good thermal/electrochemical stability of the ternary salt system. Our findings provide an effective method on fabrication of solid-state batteries for practical applications.