Enhancement of electrochemical performance of sodium-ion battery cathode material Na0.67Ni0.33Mn0.67O2 by Zn/Al co-substitution

[Display omitted] •Using Zn/Al co-substitution design gave Na0.67Ni0.2Zn0.13Mn0.62Al0.05O2.•Improvement of crystal structure reversibility.•The electrochemical performance was enormous enhanced after treatment.•Improve the conductivity of Na+ and reduce the impedance.•Simple operation and high efficiency. P2-Na0.67Ni0.33Mn0.67O2 cathode material is considered as an ideal cathode material for sodium-ion batteries due to its high capacity. However, it has P2-O2 phase transition, which leads to fast capacity decay. This paper investigates the effect of Zn/Al co-substitution on their chemical-electrical properties. The experimental results show that this strategy successfully transforms the unfavorable P2-O2 phase transition that occurs in the material during cycling into a reversible P2-OP4 phase transition, and the reversible capacity and capacity retention of the P2-type cathode material are significantly improved. It maintains a high energy density of up to 444 Wh·Kg−1 in the first five charge/discharge cycles, facilitating the future practical implementation and commercialization of the material.