4.8 V and All-Climate (-60 to 55°C) All-Solid-State Batteries Enabled by Dual-Phase Symbiotic Halide Solid Electrolytes.

Overcoming the intrinsic trade-off between high-voltage compatibility, thermal stability, and low-temperature ionic conductivity in halide solid electrolytes remains a critical challenge for advancing all-solid-state lithium batteries (ASSLBs). Here, we propose a chemical symbiosis strategy to design a dual-phase halide electrolyte integrating nanocrystalline LiAlCl4 with amorphous Li-M-O-Cl (M = Ta/Al) phases. This innovative architecture synergistically combines the ultra-high-voltage stability (up to 4.8 V) of the crystalline phase with the low-energy-barrier ion transport pathways in the amorphous matrix. The designed electrolyte exhibits exceptional electrochemical performance under extreme conditions. It enables the ASSLBs to achieve a 90.5% capacity retention after 100 cycles at 4.8 V, maintain a specific capacity of 133 mA h g-1 over 500 cycles at 55 °C and 3 C, and deliver unprecedented low-temperature performance with a capacity of 109.6 mA h g-1 and 1800-h stability under dual extreme conditions of -60°C and 4.8 V. Comprehensive characterization reveals the amorphous phase facilitates facile percolation networks for rapid Li+ conduction, while the nanocrystalline domains maintain structural integrity against high-voltage degradation. The electrolyte's broad compatibility with diverse cathodes (LiCoO2, LiNi0.8Co0.1Mn0.1O2) also underscores its versatility for high-energy ASSLBs.