Recent Progress of P2‐Type Layered Transition‐Metal Oxide Cathodes for Sodium‐Ion Batteries

Sodium‐ion batteries (SIBs) have attracted much attention due to their abundance, easy accessibility, and low cost. All of these advantages make them potential candidates for large‐scale energy storage. The P2‐type layered transition‐metal oxides (NaxTMO2; TM=Mn, Co, Ni, Ti, Fe, V, Cr, and a mixture of multiple elements) exhibit good Na+ ion conductivity and structural stability, which make them an excellent choice for the cathode materials of SIBs. Herein, the structural evolution, anionic redox reaction, some challenges, and recent progress of NaxTMO2 cathodes for SIBs are reviewed and summarized. Moreover, a detailed understanding of the relationship of chemical components, structures, phase compositions, and electrochemical performance is presented. This Review aims to provide a reference for the development of P2‐type layered transition‐metal oxide cathode materials for SIBs. Seeking suitable structures: The P2‐type layered transition‐metal oxides (NaxTMO2, TM=transition‐metal element), as cathodes for sodium‐ion batteries (SIBs), have potential for large‐scale commercial applications. Herein, structural evolution, anionic redox reactions, some challenges, and recent progress of the application of NaxTMO2 cathodes for SIBs are reviewed and summarized.