Suppressing the P2 − O2 phase transformation and Na+/vacancy ordering of high-voltage manganese-based P2-type cathode by cationic codoping

High-voltage and low-cost manganese-based P 2-type oxides show real promise as promising cathode for sodium-ion batteries (SIBs). But the P 2 − O2 phase transformation and Na + /vacancy ordering results in the inferior structural stability and Na + diffusion coefficient , which further leads to rapid decay of capacity and poor rate capability. Herein, in consideration of the synergetic effects of dual cationic doping, electrochemically inactive Li + and active Co 3+ codoping are proposed to solve the above issues. The novel two-step doping strategy, Co doping during synthesis of precursors via coprecipitation reaction followed by Li doping during solid-state reaction, are rationally developed. As anticipated, the Li/Co codoped P 2-type oxide exhibits the absence of P 2 − O2 phase transformation and Na + /vacancy disordering, which gives rise to an outstanding cycling stability (86.7% capacity retention within 100 cycles at 0.1C) and high-rate capability (reversible capacity of 109 mAh g −1 even at 10C). In addition, the full-cells composed of the codoped P 2-type positive and hard carbon negative show high energy-density, good lifespan and high-rate property. This proposed cationic codoping provides an effective and scalable tactics for modulating the structural properties of high-voltage P 2-type cathodes for advanced SIBs.