Layered oxides are the most prevalent cathodes for sodium-ion batteries (SIBs), but their poor air stability significantly limits their practical application owing to the rapid performance degradation of aged materials and the cost increase for material storage and transportation. Here, an effective strategy of constructing stable transition metal (TM) layers with a highly symmetrical six-TM ring is suggested to enhance structure stability, thus hindering ambient air corrosion. The density functional theory calculations reveal that the higher symmetry ensures a higher thermodynamic energy for H 2 O insertion into Na layer. The combined analyses of selected area electron diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and chemical titration indicate that the six-TM ring structure can effectively suppress the series of aging processes including water insertion, the spontaneous loss of lattice sodium, TM valence increment and residual alkali formation. Benefiting from the overall suppression of aging process, the strategy results in an excellent improvement in capacity retention after air exposure from 13.57% to 95.59%, and exhibits a good universality for both P2-and O3-cathodes, which are the two most common structures of Nabased layered oxides with different aging mechanism. These findings provide new insight to design high-performance cathodes for SIBs.

Two kinds of crystal orderings in layered oxides typically exhibit opposite influences on performances: Na+/vacancy ordering in alkali metal layers with an unfavorable effect on electrochemical performance and the cation ordering in transition metal layers with a positive effect on air stability. However, because the two kinds of orderings are associated with each other and often occur at the same time, it is difficult to achieve an excellent comprehensive performance. Herein, we propose a strategy of introducing a new cation ordering to construct the coexistence of Na+ disordering and transition metal ordering. An absolute solid‐solution reaction mechanism is realized in the Na+ disordered system, resulting in a superior cycling stability of 90.4% retention after 150 cycles and a rate performance of 82.7 mAh g−1 capacity at 10C, much higher than the original 81.3% and 66.4 mAh g−1. Simultaneously, the cation ordering strengthens the interlayer interaction and inhibits the insertion of water molecules from the air, ensuring stable lattice stability and thermostability after air exposure. The synergy of dis‐/ordering configuration provides new insights to design high‐performance layered oxide cathode materials for secondary‐ion batteries.

Front cover image: Layered transition metal oxides are potential cathode materials for sodium ion batteries (SIBs). However, the poor air stability, Na+/vacancy ordering, and complex phase translation significantly limit their practical application. The synergy of dis‐/ordered configuration could relieve these problems. In article number https://doi.org/10.1002/cnl2.53, a strategy of introducing new cation ordering has been proposed to construct the coexistence of Na+ disordering and transition metal ordering in layered oxide cathodes. The synergy of dis‐/ordered configuration ensures the superior comprehensive performance originating from the suppressed P‐O phase transition, suppressed Na+ rearrangement, and inhibited insertion of foreign molecules. These findings provide new insights to design high performance layered oxide cathode materials for secondary‐ion batteries.