Intercalation-Type Halide Cathode Material for All-Solid-State Lithium Batteries

All-solid-state lithium batteries (ASSLBs) have garnered widespread attention due to their safety and high energy density. However, their electrochemical performances are significantly limited by the cathode materials. Herein, we present a layered halide cathode material, TiCl₃, suitable for halide-based ASSLBs. TiCl₃ undergoes reversible redox reactions, facilitating the insertion and extraction of Li⁺ at the Li1 and Li2 sites situated between the TiCl₆ octahedral interlayers without any phase transformation. The ASSLBs utilizing TiCl₃ as the cathode demonstrate a capacity of up to 170.6 mAh g^-1, satisfactory rate performance, and excellent cycling stability, with a capacity retention of 81.4% after 200 cycles at 0.2 C. Long-term cycling neither causes a significant increase in impedance nor produces obvious element diffusion at the cathode/solid-state electrolyte interface, demonstrating the compatibility between them. This study will greatly promote the development of new cost-effective halide cathode materials and contribute to the industrialization of ASSLBs.