Dual-Function Modifications for High-Stability Li-Rich Cathode Toward Sulfide All-Solid-State Batteries

With the growing demand for high-energy-density lithium-ion batteries, Li-rich Mn-based layered oxide (LLO) cathodes with high specific capacity and low cost receive significant attention in conventional liquid lithium-ion batteries. However, LLO is rarely used in sulfide all-solid-state lithium batteries (ASSLBs) because of severe interfacial side reactions with sulfide solid electrolytes (SEs), especially at a high operation voltage of 4.8 V (vs Li/Li + ). In this work, a dual-function modification strategy is proposed to enable electrochemically stable LLO in sulfide ASSLBs. The covalent Ru─O bond formed by Ru-doping can not only stabilize lattice oxygen, preventing further interfacial decomposition involving oxygen, but also enhance the ability of Li diffusion in Li 2 MnO 3 component, and then stimulate the activation of Li 2 MnO 3 phase. Meanwhile, the surface sulfidation strategy establishes a highly stable interface, contributing to the rapid ionic transport at LLO/LPSCl interface. Results show that the modified LLO in sulfide ASSLBs delivers two times higher initial discharge capacity and an extra-long life of 2022 cycles of up to 4.2 V (vs Li–In) (with >70% capacity retention at 1 C). This research enriches the strategies for improving interfacial compatibility between LLO cathodes and sulfide SEs, thus providing new inspiration for guiding the application of LLO in sulfide ASSLBs.