Na-based layered iron-manganese oxide Na_0.67Fe_0.5Mn_0.5O₂ containing only low-cost elements is a promising cathode for Na-ion batteries used in large-scale energy storage systems. However, the poor cycle stability restricts its practical application. The capacity decay of Na_0.67Fe_0.5Mn_0.5O₂ mainly originates from the irreversible anionic redox reaction charge compensation due to the high-level hybridization between oxygen and iron. Herein, we rationally design a surface Ti doping strategy to tune the anionic redox reaction activity of Na_0.67Fe_0.5Mn_0.5O₂ and improve its Na-storage properties. The doped Ti ions not only enlarge the Na migration spacing layer but also improve the structure stability thanks to the strong Ti–O bond. More importantly, the d0-shell electronic structure of Ti⁴⁺ can suppress the charge transfer from the oxidized anions to cations, thus reducing the anionic redox reaction activity and enhancing the reversibility of charge compensation. The modified Na_0.67Fe_0.5Mn_0.5O₂ cathode shows a reversible capacity of 198 mA h g⁻¹ and an increased capacity retention from 15% to 73% after about 1 month of cycling. Meanwhile, a superior Na-ion diffusion kinetics and rate capability are also observed. This work advances the commercialization process of Na-based layered iron-manganese oxide cathodes; on the other hand, the proposed modification strategy paves the way for the design of high-performance electrode materials relying on anionic redox reactions.

仅包含低成本元素的钠基层状铁锰氧化物 Na _0.67 Fe _0.5 Mn _0.5 O ₂是用于大规模储能系统的钠离子电池的有前途的正极。然而，较差的循环稳定性限制了其实际应用。Na _0.67 Fe _0.5 Mn _0.5 O ₂的容量衰减主要源于氧和铁之间的高水平杂化导致的不可逆阴离子氧化还原反应电荷补偿。在此，我们合理设计了一种表面Ti掺杂策略来调节Na _0.67 Fe _0.5 Mn _0.5 O的阴离子氧化还原反应活性。₂提高其储钠性能。掺杂的 Ti 离子不仅扩大了 Na 迁移间隔层，而且由于强的 Ti-O 键而提高了结构稳定性。^{更重要的是，Ti 4+}的d0-壳层电子结构可以抑制电荷从被氧化的阴离子向阳离子的转移，从而降低阴离子氧化还原反应活性，增强电荷补偿的可逆性。改性的 Na _0.67 Fe _0.5 Mn _0.5 O ₂正极显示出 198 mAh g ^{-1的可逆容量}循环约 1 个月后，容量保持率从 15% 提高到 73%。同时，还观察到了优异的钠离子扩散动力学和倍率性能。这项工作推进了钠基层状铁锰氧化物正极的商业化进程；另一方面，所提出的改性策略为基于阴离子氧化还原反应的高性能电极材料的设计铺平了道路。