Sustainable Anionic Redox by Inhibiting Li Cross-Layer Migration in Na-Based Layered Oxide Cathodes

The irrational utilization of an anionic electron often accompanies structural degradation with an irreversible cation migration process upon cycling in sodium-layered oxide cathodes. Moreover, the insufficient understanding of the anionic redox involved cation migration makes the design strategies of high energy density electrodes even less effective. Herein, a P3-Na_0.67Li_0.2Fe_0.2Mn_0.6O₂ (P3-NLFM) cathode is proposed with the in-plane disordered Li distribution after an in-depth remolding of the Li ribbon-ordered P3-Na_0.6Li_0.2Mn_0.8O₂ (P3-NLM) layered oxide. The disordered Li sublattice in the transition metal slab of P3-NLFM leads to the dispersed |O_2p orbitals, the lowered charge transfer gap, and the suppressed phase transition at high voltages. Then the enhanced Mn-O interaction and electronic stability are disclosed by the crystal orbital Hamilton population (COHP) analysis at high voltage in P3-NLFM. Furthermore, ab initio molecular dynamics (AIMD) simulation suggests the order/disorder of the transition metal layer is highly correlated with the stability of the Li sublattice. The cross-layer migration and loss of Li in P3-NLM are suppressed in P3-NLFM to enable the high reversibility upon cycling. As a result, the P3-NLFM delivers a high capacity of 163 mAh g^-1 without oxygen release and an enhanced capacity retention of 81.9% (vs 42.9% in P3-NLM) after 200 cycles, which constitutes a promising approach for sustainable oxygen redox in rechargeable batteries.