Sm/O Co-doped zirconium chloride electrolytes for solid-state Li batteries

Abstract

The development of solid-state batteries with high safety and energy density is critical for next-generation storage. However, conventional halide electrolytes like Li2ZrCl6 suffer from low room-temperature ionic conductivity. We propose a synergistic Sm3+ and O2− co-doping strategy and synthesize a novel oxychloride LSZCO via ball milling. Sm3+ expands Li+ migration channels, while O2− induces local disorder to build an isotropic fast-ion network. The optimized LSZCO-1.250 achieves 1.204 mS cm−1 conductivity, 0.296 eV activation energy. Assembled all-solid-state batteries with Li6PS5Cl buffer, Li–In anode, and NCM811@LNO or LCO cathodes show at 0.1 A g−1 an initial discharge capacity of 171 mAh g−1 for NCM811, with 50.3% retention after 250 cycles, and 86.2% retention after 70 cycles for LCO. Rate tests confirm capacity recovery after high currents, indicating good interfacial stability. This work provides an effective doping strategy for high-conductivity oxyhalide electrolytes.