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, Li2.6In0.8Ta0.2Cl6 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.