Layered oxides NaMO_2(M is one metal or several metals mixture)are a potential materials,which can be used as cathodes for commercial sodium ion battery.These oxides’crystal structures can be divided into two groups of P2and O3types according to the sodium positions and arrangement ways of oxygen in the structure. Layered oxides NaMO 2 (M is one metal or several metals mixture) are a potential materials, which can be used as cathodes for commercial sodium ion batteries. These oxides’ crystal structures can be divided into two groups of P2 and O3types according to the sodium positions and arrangement ways of oxygen in the structure.