Modulating the Interlayer Spacing and Na+/Vacancy Disordering of P2-Na0.67MnO2 for Fast Diffusion and High-Rate Sodium Storage

Modulating the interlayer spacing and Na + /vacancy disordering can significantly affect the electrochemical behavior of P2-type cathode materials. In this work, we prepare a series of P2-Na 0.67 MnO 2 cathodes (Na 0.67 Ni 0.2– x Mn 0.8 Mg x O 2 ) with varying doping amounts of Mg and Ni to realize the maximization of the interlayer spacing within the experimental range and optimize the Na + /vacancy ordering. Consequently, the as-prepared Na 0.67 Ni 0.1 Mn 0.8 Mg 0.1 O 2 illustrates an excellent rate performance of 193 mA h g –1 discharge capacity at 0.1 C (1 C = 180 mA g –1 ), and even at a high rate of 8 C, the battery can deliver a capacity of 70 mA h g –1 . The kinetics analysis indicates the raising of Na + mobility, which could due to the reduced Na + /vacancy ordering and the enhanced Na interlayer spacing. The codoping of Ni and Mg also enhances the stability of the layered structure, leading to improved cycling performance of 74.7% capacity retention after 100 cycles.