石墨烯和硼氮类石墨烯对LiFePO4表面结构的改进及其电导的促进作用

利用密度泛函理论研究石墨烯和硼氮类石墨烯包覆对LiFePO₄ (010)表面结构和电导性质的影响. 结果表明包覆层和LiFePO₄ (010)表面之间的相互作用可以改善LiFePO₄ (010)表面的电导性能. 石墨烯包覆LiFePO₄ (010)表面后, 禁带宽度从3.3 eV减小到2.1 eV. 硼氮类石墨烯包覆LiFePO₄ (010)表面后, 虽然其价带顶和导带底仍由Fe的3d轨道贡献, 但禁带中出现两个间隔为0.6 eV的带隙态, 由硼氮类石墨烯与LiFePO₄(010)表面有直接接触并形成共价键的B原子和N原子贡献.

Improvement of Surface Structure and Enhancement of Conductivity of LiFePO4 Surface by Graphene and Graphene-Like B-C-N Coating

Density functional theory calculations are used to investigate the surface structure and electric conductivity of the (010) surface of LiFePO₄ coated with graphene or graphene-like B-C-N. The calculations indicate that the interaction between the coating and LiFePO₄ (010) surface improves the electric conductivity of the LiFePO₄ (010) surface. The band gap decreases from 3.3 to 2.1 eV when the LiFePO₄ (010) surface is coated with graphene. When the LiFePO₄ (010) surface is coated with graphene-like B-C-N, the valence band maximum and conduction band minimum are still dominated by Fe-3d orbitals; however, two in-gap states with an interval of 0.6 eV appear in the band gap, which are attributed to the bonding interaction between graphene-like B-C-N and the LiFePO₄ (010) surface.