Suppressing the P2–O2 Phase Transition of Na 0.67 Mn 0.67 Ni 0.33 O 2 by Magnesium Substitution for Improved Sodium‐Ion Batteries

Room-temperature sodium-ion batteries (SIBs) have shown great promise in grid-scale energy storage, portable electronics, and electric vehicles because of the abundance of low-cost sodium. Sodium-based layered oxides with a P2-type layered framework have been considered as one of the most promising cathode materials for SIBs. However, they suffer from the undesired P2-O2 phase transition, which leads to rapid capacity decay and limited reversible capacities. Herein, we show that this problem can be significantly mitigated by substituting some of the nickel ions with magnesium to obtain Na0.67 Mn0.67 Ni0.33-x Mgx O2 (0≤x≤0.33). Both the reversible capacity and the capacity retention of the P2-type cathode…

• NN
  National Natural Science Foundation of China

  Awards: 21127901, 51225204, 21303222
• CA
  Chinese Academy of Sciences