Li3InCl6 electrolyte with high voltage compatibility for Ni-rich layered oxide cathodes-based all-solid-state batteries

The sulfide electrolyte-based all-solid-state batteries with high-nickel layered oxide cathodes face significant challenges due to the narrow electrochemical window of sulfides and severe side reactions caused by direct contact with high-voltage oxide cathode materials such as LiNi_0.9Mn_0.05Co_0.05O₂ (NCM90). Here, we successfully synthesized Li₃InCl₆ (LIC) halide electrolytes through ball-milling followed by annealing method, achieving the ionic conductivity of 2.0 mS cm⁻¹ at room-temperature. The interface between this electrolyte and NCM90 cathode material without any interface modification is stable. By introducing the LIC electrolyte layer, the NCM90/LIC+Cl1.5/Li-In battery exhibits significantly improved electrochemical performance at different temperatures, particularly in terms of initial discharge capacity. Notably, the battery demonstrates outstanding discharge capacity and cycling stability at low temperatures. Experimental investigations reveal that the introduction of the LIC electrolyte with high oxidation potential facilitates the H2-H3 phase transition in NCM90 during high-voltage operation, which is critical for enhancing the discharge capacity. This work provides fundamental insights into interfacial engineering strategies for high-voltage sulfide-based all-solid-state battery systems.