Recent progress in high-voltage P2-Na TMO₂ materials and their future perspectives

P2-type layered materials (Na TMO₂) have become attractive cathode electrodes owing to their high theoretical energy density and simple preparation. However, they still face severe phase transition and low conductivity. Current research on Na TMO₂ is mostly focused on the modification of bulk materials, and the application performances have been infrequently addressed. This review summarizes the information on current common P2-Na TMO₂ materials and discusses their sodium-storage mechanisms. Furthermore, modification strategies to improve their performance are addressed for practical applications based on a range of key parameters (output voltage, specific capacity, and lifespan). We also discuss the future development trends and application prospects for P2 cathode materials.