High-entropy oxides have expanded the potential for high-performance Na-ion battery cathodes due to their vast compositional space and entropy-driven stabilization. However, a rational design approach for optimizing their composition is still lacking. Here, we develop an O3-type oxide cathode composed of all-3d transition metals, NaNi_0.3Cu_0.1Fe_0.2Mn_0.3Ti_0.1O₂ (NCFMT), which exhibits improved reversible specific capacity and exceptional cycling stability. Replacing Ti⁴⁺ with Sn⁴⁺ ions (NaNi_0.3Cu_0.1Fe_0.2Mn_0.3Sn_0.1O₂; NCFMS) results in poor structural reversibility and diminished cycling stability. Our investigations suggest that the structural integrity of the layered cathode is affected by the compatibility of constituent elements within the transition metal layers (TMO₂). In NCFMS, planar strain induced by metal-ion displacement triggers elemental segregation and crack formation during repeated cycling. In contrast, NCFMT demonstrates a robust structural framework for stable Na⁺ storage due to its high mechanochemical compatibility among constituent elements. This understanding provides insights for designing outstanding layered high-entropy cathode materials.

高熵氧化物由于其巨大的组成空间和熵驱动的稳定性，扩大了高性能钠离子电池阴极的潜力。然而，仍然缺乏优化其组成的合理设计方法。在这里，我们开发了一种由全 3 d过渡金属 NaNi _0.3 Cu _0.1 Fe _0.2 Mn _0.3 Ti _0.1 O ₂ (NCFMT) 组成的 O3 型氧化物阴极，它具有改进的可逆比容量和出色的循环稳定性。用Sn ⁴⁺离子（NaNi _0.3 Cu _0.1 Fe _0.2 Mn _0.3 Sn _0.1 O ₂ ；NCFMS）代替Ti ⁴⁺会导致结构可逆性差并降低循环稳定性。我们的研究表明，层状阴极的结构完整性受到过渡金属层（TMO ₂ ）内组成元素的相容性的影响。在 NCFMS 中，金属离子位移引起的平面应变在重复循环过程中触发元素偏析和裂纹形成。相比之下，NCFMT 由于其组成元素之间的高机械化学相容性而表现出用于稳定 Na ⁺存储的稳健结构框架。这种理解为设计出色的层状高熵阴极材料提供了见解。