Electrochemical performance and interfacial stability in Ni-rich NCM/ halide solid state batteries

The widespread adoption of Li-ion batteries in energy storage and power applications necessitates advancements in energy density, safety, and reliability. All-solid-state Li-ion batteries (SSBs) are a promising direction. This study investigates the interfacial behavior of LiNi 0.83 Co 0.14 Mn 0.03 O 2 (NCM83)/Li 3 InCl 6 (LIC) SSBs at high potentials (≥4.3 V) before and after cycling. AC impedance analysis reveals increased interfacial impedance at high potentials, particularly during constant-current/constant-voltage charging, indicating interfacial instability. High-resolution transmission electron microscopy (HR-TEM) identifies a 5 nm rock-salt phase on NCM83 at 4.3 V, thickening to 12 nm at 4.5 V, accompanied by a 15 nm lattice distortion layer. X-ray absorption spectroscopy (XAS) confirms Ni 3 + /4 + reduction to Ni 2+ , correlating with rock-salt phase formation. X-ray photoelectron spectroscopy (XPS) detects Cl and In oxides on LIC at 4.5 V, suggesting interfacial reactions. Scanning electron microscopy (SEM) reveals cracks at the NCM83/LIC interface and within the LIC electrolyte, causing interfacial contact loss and structural degradation. In situ X-ray diffraction (XRD) attributes this to volume changes during H2–H3 phase transitions in NCM83. As a result, there are interfacial reactions at high potentials and interfacial contact loss during cycling. Electrode-dense structure damage of NCM83 in LIC-based SSBs leads to accelerated electrochemical performance degradation at high potentials.