A Review of Degradation Mechanisms and Recent Achievements for Na‐Ion Layered Transition Metal Oxides

Due to the low price and high specific capacity, sodium ion batteries (SIBs) have become a crucial candidate for the future large‐scale energy storage power station, providing strong support for energy transition. Layered transition metal oxides (LTMOs), as one of the most promising cathode materials for SIBs, are usually accompanied by the sodiation/de‐sodiation during charging/discharging, which leads to the slippage and deformation of the layered structure, and consequently causes to the degradation of electrochemical performance. The degradation mechanisms of LTMOs attributed to the structural change are important references for improving the electrochemical performance of cathode materials. Here, this paper presents the main degradation mechanisms such as irreversible anion redox reaction, Na+/vacancy ordering transition and poor air stability as well as the corresponding modification means. It also summarizes the challenges faced by sodium‐ion LTMOs cathode materials, and gives an outlook on the key issues that need to be solved for future development.