Stabilizing the interface between high-Ni oxide cathode and Li6PS5Cl for all-solid-state batteries via dual-compatible halides

Abstract

All-solid-state batteries (ASSBs) with enhanced safety are promising next-generation energy storage systems for electric vehicles. However, the utilization of ASSBs is hindered by the high interfacial resistances between high-Ni-oxide cathodes and sulfide solid electrolytes (SEs). Passivating interphases form on the cathode in contact with the SE upon charging, deteriorating the power capability and cyclability. Inspired by the excellent stability of halides at high voltages, herein, we propose the interfacial engineering of LiNixCoyMnzO2 (NCM) and Li6PS5Cl (LPSCl) using Li+-conductive halides with ʻdual compatibilityʼ. The charge-transport and interfacial resistances of the halide-coated NCM (NCM@halide) electrodes are analyzed using a transmission-line-based impedance model. Impedance analyses indicate that the interfacial halide nanolayers slightly increase the Li+-transport resistance, but the NCM@halide electrodes exhibit considerably lower interfacial resistances than bare NCM. Furthermore, the interfacial resistance is highly dependent on the halide composition: NCM@Li2ZrCl6 shows a lower interfacial resistance than NCM@Li3InCl6 and NCM@Li3YCl6, resulting in superior rate-capability and cycling stability. The composition-dependent electrochemical properties of the NCM@halide electrodes are discussed in terms of the dual compatibility of the halides with NCM and LPSCl. This study offers an effective approach for addressing the interfacial challenges of sulfide-based ASSBs with high-Ni oxide cathodes.