Mitigating the P2–O2 phase transition of high-voltage P2-Na2/3[Ni1/3Mn2/3]O2 cathodes by cobalt gradient substitution for high-rate sodium-ion batteries

A nanoscale cobalt gradient substitution is introduced to suppress the P2–O2 phase transition and improve the Na⁺ kinetics of high-voltage P2-Na_2/3[Ni_1/3Mn_2/3]O₂ cathodes for sodium-ion batteries.