Breaking the Vicious Spiral to Suppress Oxygen Loss in Li‐Rich Oxide Cathode Materials

Abstract The irreversible oxygen loss (O‐loss) hinders the application of oxygen redox (O‐redox) cathode material in high‐energy‐density Li/Na‐ion batteries. Although O‐loss is commonly associated with O 2 release, the underlying mechanism remains unclear, which is not a simple surface problem. Herein, the O‐loss/redox behaviors of the layered Li 2 MnO 3 and spinel Li 4 Mn 5 O 12 are comparatively investigated through experiments and density functional theory (DFT) calculations. It shows that the vicious spiral between O─O dimerization and Mn migration drive the void growth, chain‐like structural collapse, and O 2 release in Li 2 MnO 3 . In contrast, the stable spinel framework and inert O in O‐LiMn 3 coordination of Li 4 Mn 5 O 12 break this spiral and trap O 2 within the bulk, ensuring a reversible O‐redox. By atomically compositing Li 4 Mn 5 O 12 with LiNi 0.5 Mn 1.5 O 4 , a novel Co‐free Li‐rich spinel oxide (LRSO) with high energy density (>1000 Wh kg −1 ) is produced. These findings clarify the correlation between structural rearrangement and O‐redox and contribute to the design of advanced O‐redox cathode materials.