锑烯吸附金属Li原子的密度泛函研究

Density functional study of metal lithium atom adsorption on antimonene

锑烯(antimonene)是继石墨烯和磷烯之后出现的新型二维材料,在锂离子电池等领域受到关注.本文基于第一性原理的密度泛函理论,计算研究了锑烯对Li原子的吸附特性,包括Li原子的最稳定吸附构型、吸附密度以及吸附Li原子的扩散路径.结果表明:Li原子最稳定的吸附位置位于谷位,即底层Sb原子之上、顶层三个Sb原子中心位置,吸附能为1.69 eV,吸附距离为2.81?;能带计算发现,锑烯为带隙宽度1.08 eV的间接带隙半导体,吸附Li原子后费米能级上升进入导带,呈现出金属性;原子分波态密度分析发现, Sb原子的p电子态和Li原子的p和s电子态形成明显的共振交叠,表现出杂化成键的特征;随着吸附Li原子数量增加,锑烯晶格结构和电子结构发生较大变化.通过微动弹性带方法计算发现, Li原子在锑烯表面的扩散势垒为0.07 eV,较小的势垒高度有利于快速充放电过程.

Since the discovery of graphene, researchers have been being increasingly attracted by the emerging of a bunch of two-dimensional(2 D) materials, such as BN, MoS2 and black phosphorene. These materials possess outstanding physical and chemical properties, which could find great potential applications in nanoelectronics,energy conversion or storage, photocatalysts, etc. Recently, a theoretically predicted pucker layered material consisting of Sb atoms, antimonene, has been prepared, and is attracting the attention in the field of lithium ion batteries.In this paper, based on first-principle density functional theory, the adsorption characteristics of Li atoms on antimony are studied, including the most stable adsorption configuration, the adsorption density and the diffusion path of Li atom on antimonene. The results show that the most stable adsorption configuration of Li atom is in the valley site, i.e. the center of the three Sb atoms in the top layer and one Sb in the bottom layer.The adsorption energy is 1.69 eV and the adsorption distance is 2.81 ?. The band structure shows that antimony is an indirect band gap semiconductor with a band gap of 1.08 eV. After the absorption of Li atom,the Fermi level enters into the conduction band, which shows an electronic property similar to metal. The analysis of density of states shows that the p-electronic state of Sb atom and the p and s electronic state of Li atom possess distinct resonance peaks, showing hybrid bonding characteristics. With the increase of the number of Li atoms adsorbed, the lattice structure and electronic structure of antimonene change greatly. The nudged elastic band calculation shows that the diffusion barrier of Li atom on antimony surface is 0.07 eV, and a smaller barrier height is beneficial to the rapid charge-discharge process. To sum up, antimony has a good potential as an anode material for lithium ion batteries.