In order to understand the above findings, density functional theory (DFT) calculations were used to study the effect of Mg and Sc doping on the lattice parameters and the redox mechanism of P2-NaxNi0.33Mn0.67O2. The atomic structures of the three materials with Na contents of x=0.67 and 0.22 (corresponding to the OCV and fully charged states, respectively) were determined (see Figure and Table ) by performing an extensive set of Coulomb energy and DFT calculations as discussed in the method section. The computed lattice parameters using DFT-PBE+U and DFT-PBE+U+D3 agree with the experimental observations and confirm the oxidation of TMs with desodiation. (For further details, see Table in the Supporting Information).