硅纳米团簇与石墨烯复合结构储锂性能的第一性原理研究

本文采用第一性原理计算方法, 研究了不同晶向硅纳米团簇与石墨烯复合结构稳定性及其储锂性能. 计算了不同高度、大小硅团簇与石墨烯复合结构的结合能, 复合结构中嵌锂吸附能和PDOS. 分析表明, 硅团簇和石墨烯之间形成较强的Si—C键, 其中111]晶向硅团簇与石墨烯作用的形成能最高, 结构最为稳定. 进一步计算其嵌锂吸附能, 发现硅团簇中靠近石墨烯界面处的储锂位置更加有利于锂的吸附, 由于锂和碳、硅之间有较强电荷转移, 其吸附能明显大于其他储锂位置. 同时在锂嵌入过程中, 由于石墨烯的引入, 明显减小了界面处硅的形变, 有望提高其作为锂电池负极材料的可逆容量.

First-principles study on the Li-storage performance of silicon clusters and graphene composite structure

This paper focuses on the Li-storage performances and the stabilities of the hybrid structure of different lattice planes of the silicon clusters and graphene by the first-principles theory. In this paper, we calculate the binding energy, the adsorption energy, and the PDOS of the hybrid structure of the different heights and sizes of the silicon clusters and graphene. We figure out that strong Si-C bonds between the silicon cluster and graphene can form. Especially, the hybrid structure of the silicon clusters with plane (111) and graphene performs best with the highest formation energy and the outstanding stability. According to the calculation of Li-absorption energy, we conclude that the location of the silicon cluster near the graphene has higher possibility and higher absorption energy of the Li storage, owing to the charge transfers between lithium and carbon, and between lithium and silicon. Because the graphene is used, the deformation of the interface of the silicon cluster can be obviously reduced during the absorption of Li, which brings about a good future for the hybrid structure used as the battery anode materials.