锂离子电池中石墨烯阳极磷掺杂效应的原子学研究
Atomistic Insights into the Effects of Phosphorous Doping of Graphene Anode in a Lithium Ion Battery
摘要：
受最近的实验和理论研究的启发[Yang等人，2017]，其中石墨烯中的突起已被提出作为增强钠离子电池性能的有效策略，通过使用密度泛函理论进行石墨烯中磷掺杂对Li的吸附和扩散行为的影响的全面研究。我们发现，在石墨烯中引入P-掺杂剂的突起增强了单个Li原子到阳极上的吸附，这是由于Li和衬底的碳原子之间的额外的部分共价键合特性。然而，随着Li原子浓度的增加，它们倾向于形成团簇，这可能导致枝晶生长并因此导致电池失效。费米能级的有限态密度保证了P掺杂石墨烯在吸附Li原子前后的电子导电性。除了费米能级随Li浓度的增加有一个小的上移外，没有观察到DOS的显著变化。这种突起的存在充当Li的捕获中心，并阻碍它们在衬底上的迁移，导致阳极的循环性能差。这一原子水平的研究将为进一步开发新型电池技术的阳极材料提供有用的指导。
英文摘要：
Inspired by a recent experimental and theoretical study [Yang et al., 2017], wherein protrusions in graphene have been proposed as an effective strategy to enhance the performance of sodium ion batteries, a comprehensive study of the effects of phosphorus doping in graphene on adsorption and diffusion behaviour of Li is carried out by using density functional theory. We find that protrusion introduced by P-dopant in graphene enhances the adsorption of a single Li atom onto the anode due to an additional partial covalent bonding character between Li and carbon atoms of the substrate. However, with increase in concentration of Li atoms, they tend to form clusters which may lead to dendrite growth and hence battery failure. Finite density of states at Fermi level ensures the electronic conductivity of the P-doped graphene before and after the adsorption of a Li atom. No momentous variation in DOS is observed except a small up shift in Fermi level with increased Li concentration. The presence of such protrusions acts as trapping centres for Li and hinders their migration over the substrate, leading to poor cycling performance of anode. This atomic level study will act as a useful guideline for further development of anode materials for novel battery technologies.
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