A comprehensive modification enables the high rate capability of P2-Na0.75Mn0.67Ni0.33O2 for sodium-ion cathode materials

The Na+/vacancy ordering can effectively affect the electrochemical behavior of P2-type cathode material. In this work we proposed an integrated strategy by attaining a high Na content, In3+ doping in conjunction with NaInO2 coating in the P2-Na0.75Mn0.67Ni0.33O2 which can inhibit the sodium vacancy order, smooth the electrochemical curve, and enhance the structural stability and rate capability. A combination of X-ray diffraction analysis and DFT calculation indicate that the In3+ ions in the Na layer serve as “pillars” to stabilize the layered structure, especially for high current density charging. The P2-Na0.75Mn0.67Ni0.33In0.02O2 with an impressive sodium content exhibits a remarkable reversible capacity of 109.6 mAh g−1, superior rate capability capacity of 79.8 mAh g−1 at 20 C, and 85% capacity retention after 100 cycles at 5 C. This work demonstrates an efficient approach for the comprehensive optimization of sodium ion cathode materials.