Sulfide redox couple enabled dynamic lattice-oxygen stabilization in lithium-rich manganese oxide all-solid-state batteries

Lithium-rich manganese oxide (LRMO) emerges as a next-generation cathode material due to high operating voltage and exceptional specific capacity. Matching LRMO with solid-state electrolytes (SSEs) to develop LRMO-based all-solid-state lithium batteries (ASSLBs) is promising to achieve high energy density. However, the irreversible release of lattice oxygen triggers oxidative decomposition of SSEs and structural collapse of LRMO, posing a critical bottleneck for practical implementation. Herein, we introduce a dynamic lattice-oxygen stabilization strategy via S 2− /SO 3 2− redox couple. The failure mechanism of LRMO-based ASSLBs and the lattice-oxygen stabilization mechanism are revealed. The sulfide redox-couple coating not only suppresses oxygen release but also enables reversible oxygen redox chemistry. The Li 2 S@LRMO demonstrates outstanding electrochemical performance, delivering a high specific capacity and stably cycling over 1,000 cycles. This work provides a mechanistic insight into stabilizing lattice oxygen in LRMO-based ASSLBs, paving the way for scalable cathode design in solid-state energy storage.