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

Authors：Shi, Yuansheng; Geng, Fushan; Sun, Yang; Jiang, Pengfeng; Kan, Wang Hay; Tong, Wei; Lu, Xueyi; Qian, Guoyu; Zhang, Nan; Wei, Bin; Hu, Bingwen; Cao, Dapeng; Lu, Xia

Source：ACS Nano, 2024.

DOI：10.1021/acsnano.3c11146

• P3-Na0.67Li0.2Fe0.2Mn0.6O2
• anionic redox
• structural ordering/disordering
• Li migration
• sodium-ion batteries

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-Na0.67Li0.2Fe0.2Mn0.6O2 (P3-NLFM) cathode is proposed with the in-plane disordered Li distribution after an in-depth remolding of the Li ribbon-ordered P3-Na0.6Li0.2Mn0.8O2 (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.

• Institution
  中山大学; 中国科学院; 北京化工大学