As the representative layered oxide cathode for sodium ion batteries (SIBs) featuring the low cost, P2-type Na-Fe-Mn oxide (NFMO) delivers a high capacity but a limited cycling stability, while O3-type NFMO shows extended cycling lifespan but a lower capacity. Considering the complementarity of two phases in electrochemistry, we successfully designed and fabricated a Fe/Mn-based layered oxide Na_0.67Li_0.11Fe_0.36Mn_0.36Ti_0.17O₂ with a unique P2/O3 biphasic architecture through high-proportion Li/Ti co-substitution. High-proportion Li substitution in transition metal layers triggers the reversible O redox below 4.2 V due to the formation of the special O bonding environment, delivering a highest capacity of 235 mA h g¹ ever reported among all Fe- and Mn-based layered oxide cathodes. Moreover, the unique intersected complex way at the phase boundary significantly suppressed the P2→OP4 phase transition and decreased the lattice mismatch between two phases at high potentials, greatly enhancing the cycling stability. This novel phase complex strategy benefits the design of promising cathode materials with high capacity and long lifespan for SIBs and beyond.

作为钠离子电池（SIBs）的代表性层状氧化物正极，具有低成本的特点，P2 型 Na-Fe-Mn 氧化物（NFMO）提供高容量但循环稳定性有限，而 O3 型 NFMO 显示出更长的循环寿命但较低的容量。考虑到电化学中两相的互补性，我们成功设计并制备了 Fe/Mn 基层状氧化物 Na _0.67 Li _0.11 Fe _0.36 Mn _0.36 Ti _0.17 O ₂通过高比例的 Li/Ti 共取代具有独特的 P2/O3 双相结构。由于形成特殊的 O 键合环境，过渡金属层中高比例的 Li 取代触发了低于 4.2 V 的可逆 O 氧化还原，在所有 Fe 和 Mn 基层状氧化物正极中提供了有史以来报告的最高容量 235 mAh g ¹ . 此外，相边界处独特的交叉复杂方式显着抑制了 P2→OP4 相变，减少了高电位下两相之间的晶格失配，大大提高了循环稳定性。这种新颖的相复合策略有利于设计具有高容量和长寿命的 SIB 及其他正极材料。