Li在石墨烯、BC_7及C_7N表面吸附与迁移的第一性原理研究

First Principle Study on Surface Adsorption and Diffusion Behavior of Li on Graphene,BC_7,C_7N

基于密度泛函理论的第一性原理方法,本文系统研究了Li在本征石墨烯及BC7、C7N表面的吸附和迁移行为。与本征石墨烯相比,硼含量为12.5at%时提高了Li的吸附能,而氮含量为12.5at%时减弱了Li的吸附能,这归因于掺杂物种具有不同的电子结构。通过NEB方法计算了Li在本征石墨烯、BC7、C7N表面的迁移。结果表明,相比于本征石墨烯,硼含量为12.5at%的石墨烯减弱了Li的扩散,而氮含量为12.5at%的石墨烯促进了Li的扩散,有助于提高石墨烯负极材料的充放电性能。

The adsorption and diffusion behavior of Li particle on pristine graphene,BC7 and C7N surface have been systematically calculated through the first principle method. Compared with pristine graphene,boron content for 12. 5at% significantly enhances the adsorption energy of Li,whereas the adsorption energy of Li is slightly weakened when nitrogen content for 12. 5at%,which should be attributed to the different electronic structures of the dopant. The diffusion of Li on graphene,BC7,C7 N surface was also computed through nudged elastic band method,and the results reveal that compared to pristine graphene,boron content for 12. 5at% weakens the diffusion of Li,and nitrogen content for 12. 5at% promots the diffusion of Li. It helps to improve the performance of graphene anode materials for charge and discharge.