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

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 LiCoO₂ (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/Li₂CO₃/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 Li₁₀GeP₂S₁₂ (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.