Progress of the Elements Doped NaFeO2Cathode Materials for High Performance Sodium‐ion Batteries

Abstract Layered metal oxide NaFeO 2 has been recognized is a promising cathode material for high‐energy sodium‐ion batteries (SIBs) due to its low cost and high capacity. However, its poor structural stability during the Na + insertion/extraction results in capacity degradation and a short cycle life. Elemental doping is a very promising method to improve its performance. Here, layered iron‐based oxides (NaFeO 2 or NaFeMeO 2 [Me=manganese, nickel, and so on]) were doped with different elements (manganese, nickel, copper, fluorine, etc.) and their performance as cathode materials of SIBs are reviewed and analyzed. We found that synergistic doping with multiple cations can improve sodium storage performance. Moreover, anionic doping is also worth exploring to improve the crystal structure and the sodium storage of these materials.