High-Voltage Long-Cycling All-Solid-State Lithium Batteries with High-Valent-Element-Doped Halide Electrolytes

All-solid-state batteries (ASSBs) have garnered considerable attention as promising candidates for next-generation energy storage systems due to their potentially simultaneously enhanced safety capacities and improved energy densities. However, the solid future still calls for materials with high ionic conductivity, electrochemical stability, and favorable interfacial compatibility. In this study, we present a series of halide solid-state electrolytes (SSEs) utilizing a doping strategy with highly valent elements, demonstrating an outstanding combination of enhanced ionic conductivity and oxidation stability. Among these, Li_2.6In_0.8Ta_0.2Cl₆ emerges as the standout performer, displaying a superionic conductivity of up to 4.47 mS cm^-1 at 30 °C, along with a low activation energy barrier of 0.321 eV for Li⁺ migration. Additionally, it showcases an extensive oxidation onset of up to 5.13 V (vs Li⁺/Li), enabling high-voltage ASSBs with promising cycling performance. Particularly noteworthy are the ASSBs employing LiCoO₂ cathode materials, which exhibit an extended cyclability of over 1400 cycles, with 70% capacity retention under 4.6 V (vs Li⁺/Li), and a capacity of up to 135 mA h g^-1 at a 4 C rate, with the loading of active materials at 7.52 mg cm^-2. This study demonstrates a feasible approach to designing desirable SSEs for energy-dense, highly stable ASSBs.