Boosting oxygen redox reversibility in chemo-mechanically robust Li-rich oxides cathode via multi-scale defect design

Abstract

Li-rich oxides (LROs) cathode can deliver high-energy density established on the synergistic effect of cation and anion redox. However, continued accumulation of lattice strain and irreversible oxygen-anion redox reactions generate severe mechanically 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 the agency of tailoring the excess-Li distribution with the property of enhancing the cathode electrolyte interfacial (CEI) stability and prevent 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 cycle 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.