A Near‐Surface Structure Reconfiguration Strategy to Regulate Mn3+/Mn4+and O2−/(O2)n−Redox for Stabilizing Lithium‐Rich Oxide Cathode

Abstract

AbstractLithium‐rich layered oxides (LROs) are one class of the most competitive high‐capacity cathode materials due to their anion/cation synergistic redox activity. However, excessive oxidation of the oxygen sublattices can induce serious oxygen loss and structural imbalance. Hence, a near‐surface reconfiguration strategy by fluorinating graphene is proposed to precisely regulate Mn3+/Mn4+and O2−/(O2)n−redox couples for remarkably stabilizing high‐capacity LROs and realizing the simultaneous reduction of the lattice stress, regulation of the Mn metal at a lower charge state, and construction of 3D Li+diffusion channels. Combining with a highly conductive graphene‐coating layer, the surface oxygen loss, transition metal dissolution, and electrolyte catalytic decomposition are suppressed. Benefiting from this synergy, the modified LROs disclose higher initial Coulombic efficiency and discharge‐specific capacity and improve cyclability compared with pristine LROs. Further, it is revealed that the F−impact becomes easier for the O sites at the lattice interface ofC2/mandRmto sufficiently buffer lattice stress. Moreover, lithium ions coupled to the doped F atoms at the lattice interface migrate to the Ni‐richRmlattice sites with lower migration energies. This consolidated understanding will open new avenues to regulate reversible oxygen redox of LROs for high‐energy‐density lithium‐ion batteries.