Boosting oxygen redox reversibility in chemo-mechanically robust Li-rich oxide cathodes via multi-scale defect design†

Li-rich oxide (LRO) cathodes can deliver high-energy density based on the synergistic effect of cation and anion redox. However, continued accumulation of lattice strain and irreversible oxygen-anion redox reactions generate severe mechanical failure and rapid voltage decay in lithium-ion batteries (LIBs). Herein, we constructed a layered-spinel lattice-matched epitaxial structure with delocalized Li@Mn₆ superstructural units to intercept lattice strain-induced structural evolution and facilitate oxygen redox reversibility. This multiscale regulation strategy was realized by tailoring the excess-Li distribution, which enhances the cathode electrolyte interfacial (CEI) stability and prevents the rapid performance decay of LROs. The modified LROs achieved significant improvements, including uniform current distribution, minimal lattice strain change (0.00179), impressive initial coulombic efficiency (87.1%), exceptional thermal stability and enhanced cycling stability. Specifically, the capacity retention of the pristine LROs increased from 47.6% to 90.8% after 400 cycles. These results highlight the outstanding electro-chemo-mechanical stability of the modified LROs. Therefore, this multiscale defect-regulated strategy could help to solve the structural collapse and electrochemical decay caused by irreversible anionic redox in practical application of LROs.