Self‐Sacrificing Reductive Interphase for Robust and High‐Performance Sulfide‐Based All‐Solid‐State Lithium Batteries

Abstract All‐solid‐state lithium‐ion batteries (ASSLIBs) based on sulfide solid‐state electrolytes (S‐SSEs) are considered as one of the most promising choices to address the safety hazards of traditional lithium‐ion batteries. However, the high‐voltage cathodes, such as LiCoO 2 (LCO) with high‐valence Co (+3), tend to spontaneously oxidize S‐SSEs, causing polarization increase and rapid degradation. Herein, a self‐sacrificing reductive interphase consisting of CoO/Li 2 CO 3 /C, is in situ constructed on LCO surface via a simple carbon‐induced thermal reduction of LCO. With such a design, the Co valence of LCO surface is reduced to +2, reducing the oxidative nature of LCO to avoid reactions with S‐SSEs. As a result, ASSLIBs using Li 10 GeP 2 S 12 (LGPS) S‐SSEs achieve a high initial capacity of 144.9 mAh g ‒1 at 0.2 C and retard 93.1% of initial capacity after 100 cycles. Additionally, excellent rate cyclability of 109.2 mAh g ‒1 at 1.0 C with 81.5% retentive capacity for 200 cycles is attained as well. Comprehensive evidence strongly demonstrates the effectiveness of this self‐sacrificing reductive interphase in inhibiting the interfacial reactions and ensuring long‐term cyclability. The proposed concept of a self‐sacrificing reductive interface in this study paves the way for stabilizing the cathode/SSEs interface and offers a novel approach for the design of high‐performance sulfide‐based ASSLIBs.