First-principles study of the structural and electronic properties of LiFePO4 by graphene and N-doped graphene modification

Using first-principles calculations within the DFT + U framework, the structural and electronic properties of LiFePO4 (0 1 0) surface modified by graphene and N-doped graphene have been investigated. The calculated formation energy indicates that the graphene and N-doped graphene doped on the (0 1 0) surface of the LiFePO4(LFP) is energetically favored. N-substitution can significantly increase the impurity bands between the valence-band maximum and the conduction-band minimum, indicating better electro-conductive properties. Atomic Populations indicates that Li+ is more independent in olivine-type LFP crystal and can be embedded and exited in skeleton relatively freely after graphene and N modification.