Research progress on P2-type layered oxide cathode materials for sodium-ion batteries

The P2-Na 0.67 Ni 0.33 Mn 0.67 O 2 material, renowned for the high sodium-ion (Na+) diffusion rate and conductivity, exhibits remarkable rate capability and cycling performance, making it a promising candidate for the cathode of SIBs. However, the performance of the P2-Na 0.67 Ni 0.33 Mn 0.67 O 2 cathode is hindered due to high-voltage phase transitions, structural reconstructions, oxygen release, metal dissolution, and air sensitivity. To cope with these problems, rational component regulation and structural design have been explored in recent years, but lack of systematic analysis and organization. Herein, from the relationship between the structure and performance of materials, the related mechanisms that give rise to these problems, and the advancements in modifying P2Na 0.67 Ni 0.33 Mn 0.67 O 2 cathode through various strategies including element doping, surface engineering, multiphase composites, and innovative configuration designs are reviewed comprehensively. Finally, some insights on the innovative research direction, potential modification strategies, and development trends of P2Na 0.67 Ni 0.33 Mn 0.67 O 2 cathode are presented. This review will supply a reference for the component regulation and structural design of the P2-Na 0.67 Ni 0.33 Mn 0.67 O 2 cathode, expected to facilitate the practical application of the P2-type layered oxide cathodes.