Boosting the electrochemical performance of P2-type Mn-based cathode for SIBs by Fe-doping

P2-type layered Mn-based excess metal oxide cathode is considered to be one of the most promising cathode materials for sodium-ion batteries (SIBs) due to the open sodium ion diffusion channels and low diffusion energy barrier. However, the deep charge/discharge process of the P2-type layered oxide cathodes at high potential leads to the displacement and irreversible alterations of the crystal structure, thereby resulting in poor rate capability and deteriorated capacity retention. The charge/discharge curves are smoothed after Fe doping. The specific discharge capacity, rate capability and cycling stability of the samples are significantly improved by Fe-doping. When x  = 0.03, the obtained Na 0.6 Mn 1-x Fe x O 2 cathode delivers excellent electrochemical performance. The initial discharge specific capacity of the cathode is 193.14 mAh g −1 at 0.1C, and can remain 91.05 mAh g −1 after 100 cycles. The capacity retention rate is as high as 86.02 % when the current density turn back to 0.1C after cycles at different current densities. The present work may propose a strategy to improve P2-type layered Mn-based cathode materials for sodium-ion batteries by a doping method, which will be of great significance for the commercialization of sodium-ion batteries.