Lattice Oxygen Redox Reversibility Modulation in Enhancing the Cycling Stability of Li‐Rich Cathode Materials

Abstract The practical application of lithium‐rich layered oxides is prohibited by the drawbacks such as severe capacity and voltage degradation resulting from unstable oxygen redox environment and the accompanied irreversible oxygen release. Herein, a facile and effective strategy is proposed to regulate the oxygen redox chemistry via foreign Fe doping and its induced intrinsic transition metal (TM) doping as well as the in situ constructed spinel surface layer. The Fe doping, together with the induced intrinsic TM dual doping, can stabilize the lattice oxygen in the bulk due to the formed stronger FeO bond, and restrain the irreversible TM migration and then the undesirable phase transformation. More importantly, thermodynamical energy barrier of oxygen activation is dramatically decreased by the O 2p–Fe 3d charge‐transfer, allowing stable oxygen redox activity. And the pre‐constructed spinel layer can effectively stabilize the surface lattice oxygen and suppress harmful interfacial side‐reactions. Such a simple optimizing method make the modified cathode exhibit a high specific capacity of 298 mAh g −1 at 0.2 C, outstanding cycling stability with a superior capacity and voltage retentions of 92.5% and 90.8%, respectively, after 400 cycles at 1 C. This study provides a new direction for developing advanced Li‐ion batteries.