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

A hierarchical design strategy involving coherent O3@P2 heterostructure is introduced to improve the electrochemical performance of O3-type layered oxides . Specifically, the high Na-content P2-type layered oxide grows coherently on the O3-type lattice, stabilizing the O3-type core and providing effective channels for Na + diffusion Additionally, the P2-type multifunctional shell ensures excellent surface stability, preventing side reactions and moisture damage. This design significantly improves the cycling stability and kinetic performance of O3-type layered oxides, making it highly promising for practical application. • The O3@P2 cathode with coherent heterostructure is constructed based on gradient design. • Coherent heterostructure enhances structure stability and suppresses phase transition. • The multifunctional coating mitigates side reactions and improves surface stability. • O3@20%P2 cathode exhibits excellent electrochemical performance and air stability. 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.