氮掺杂的石墨烯作为钠离子电池负极材料的第一性原理研究
Nitrogen-doped graphene as anode materials for sodium ion batteries: a first-principles study

采用基于密度泛函理论的第一性原理方法，研究了本征石墨烯、氮掺杂的石墨烯和叽咯石墨烯吸附钠原子的电荷密度、吸附能、态密度和储存量。结果表明，三种石墨烯中，钠原子的最佳吸附位置为H位。与本征石墨烯相比，氮掺杂的石墨烯对钠原子的吸附能提高，叽咯石墨烯对钠原子的吸附能是-3.274 eV，约为本征石墨烯对钠原子吸附能的1.7倍。钠原子与叽咯石墨烯中的氮原子发生轨道杂化，而与本征石墨烯和氮掺杂的石墨烯没有发生轨道杂化现象。叽咯石墨烯能够吸附10个钠原子，与本征石墨烯相比显著提高，氮掺杂的石墨烯只能吸附4个钠原子。因此，叽咯石墨烯有望成为一种潜在的储钠材料
Abstract: We investigate the charge densities, adsorption energies, densities of states and storage capacities of Na atoms on pristine graphene, N-doped-graphene and pyrrolic graphene using the first-principles method of density functional theory combined with the pseudopotential approximation. The results indicate that the most stable site is H site in the three graphenes. The adsorption energy of Na on pyrrolic graphene is -3.274 eV, which is over 1.7 times that of Na on the pristine graphene, while the N-doped graphene has a higher adsorption energy than the pristine graphene. The orbital hybridizations can be observed in the pyrrolic graphene, while there is no orbital hybridization in the pristine graphene or N-doped graphene. Pyrrolic graphene can adsorb up to ten Na atoms, which is larger than that of pristine graphene and N-doped graphene. This work demonstrates that pyrrolic graphene is expected to be a potential materials for storing Na.