High-Voltage Induced Stable Interface Promoting Electrochemical Performance for Halide-Based All-Solid-State Batteries

Halide-based solid-state electrolytes (SSEs) exhibit favorable ionic conduction with wide electrochemical windows, yet their practical applications are significantly constrained by the interfacial instability between the electrolyte and cathode. In this work, the compatibility and interaction mechanisms between Li₃InCl₆ (LIC) and single-crystal LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode material at high voltage have been in-depth investigated. It has been found that spontaneous delithiation can be triggered via direct contact between LIC and NCM811, leading to capacity degradation. However, at a high voltage of 4.7 V, the proposed LIC-based all-solid-state battery presents exceptional cycling stability with 84.7% capacity retention after 200 cycles, outperforming that of 70.8% retention at 4.4 V. The oxidation of LIC at 4.7 V triggers a self-limiting side reaction, leading to the formation of a well-adhered cathode-electrolyte interphase (CEI) through interfacial oxygen scavenging, which suppresses further side reactions and enhances interfacial electrochemical stability. This work provides fundamental insights for designing high-voltage all-solid-state batteries (ASSBs) and advances research on cathode-electrolyte compatibility.