P2-type layered Na0.67MnO2 has been considered to be a promising candidate cathode material for sodium ion batteries.Nevertheless,the undesired phase transitions during operation and the large Na+ radius induced sluggish ion diffusion remain the stumbling blocks to realize its high performance.Herein,we propose a Zn/Mg co-doping strategy,which is proved to have bifunctional effects.First,relative to the pristine P2-Na0.67MnO2 and the single-ion (Zn/Mg) doped samples,the Zn/Mg dual-doped P2-Na0.67MnO2 demonstrates a lower Mn3+/Mn4+ ratio and a higher lattice O content,which facilitate the structural stability of the cathode material.More intriguingly,the Zn/Mg co-doping gives rise to enlarged interplanar spacing,which provides spacious ion diffusion channels for fast Na+ intercalation/extraction.As a result,the Zn/Mg dual-doped sample exhibits a high Na+ diffusion coefficient and a solid-solution reaction during charge/discharge,with a cell volume change determined to be only 0.55％.Taking advantages of the above favorable features,the Zn/Mg dual-doped P2-Na0.67MnO2 demonstrates a high rate performance with 67.2 mAh·g-1 delivered at 10 C and a decent cycling stability with a capacity retention of 93.8％ achieved at 1 C after 100 cycles.This work introduces the Zn/Mg co-doping strategy to simultaneously improve the cycling stability and rate capability of P2-Na0.67MnO2,which may offer a promising avenue for further performance enhancement of the layered Na-ion batteries cathode materials.