Constructing coherent O3@P2 heterostructures enables enhanced reversibility and kinetics of layered cathodes for sodium-ion batteries

O3-type layered oxides are considered as promising cathodes for high-performance sodium-ion batteries (SIBs) due to their high energy density and cost-effectiveness. However, their large-scale commercial application is still limited by the inevitable phase transitions, complex transition pathway and poor air stability. Herein, a hierarchical design strategy involving coherent O3@P2 heterostructure is introduced to simultaneously address these challenges. The coherently grown P2-type layered oxides act as a multifunctional shell to constrain the phase transition of the O3-type core and provide effective channels for Na⁺ diffusion, remarkably enhancing the cycling stability and diffusion kinetics. Additionally, the designed O3@P2 cathode yields a high reversible capacity (122.5 mAh g⁻¹ at 1 C) and excellent cycling capability (76.4 % capacity retention after 1000 cycles at 10 C), confirming the synergistic effect of the coherent O3@P2 heterostructure. Furthermore, the modified O3@P2 cathode enables the remarkable capacity retention in full cell (near 100 % after 100 cycles at the rate of 0.5 C). This work demonstrates that the coherent growth of surface coating contributes to enhancing the stability of layered oxides, providing valuable insights in improving the performance of O3-type layered oxides.