Mitigating the P2–O2 transition and Na+/vacancy ordering in Na2/3Ni1/3Mn2/3O2 by anion/cation dual-doping for fast and stable Na+ insertion/extraction

Ca²⁺/F⁻ co-doping mitigates P2–O2 transition and Na⁺/vacancy ordering in P2-type Na_2/3Ni_1/3Mn_2/3O₂, which significantly improves the rate capability and cycling performance due to the synergy of Ca²⁺ and F⁻.