Open AccessFirst-principles study of structural stability and lithium storage property of Si<sub><i>n</i></sub> clusters (<i>n</i> ≤ 6) adsorbed on graphene
Author(s) -
Ding Shen,
Yao-Han Liu,
Shuwei Tang,
Wei Dong,
Wen Sun,
Laigui Wang,
Shaobin Yang
Publication year - 2021
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.70.20210521
Subject(s) - graphene , materials science , lithium (medication) , crystallography , nanotechnology , chemistry , medicine , endocrinology
Silicon/carbon composite is one of the most potential high-capacity anode materials for lithium-ion batteries. The interface state between silicon and carbon of silicon/carbon composite is an important factor affecting its electrochemical performance. In this paper, Si n ( n ≤ 6) clusters with different numbers of Si atoms are constructed on graphene as a structural unit of carbon material. The geometric configuration, structure stability and electronic property of Si n clusters adsorbed on graphene (Si n /Gr) are studied by the first-principles method based on density functional theory (DFT). The results show that when the number of Si atoms n ≤ 4, the Si n clusters are preferentially adsorbed on graphene in a two-dimensional configuration parallel to graphene. When n ≥ 5, the Si n clusters are preferentially adsorbed on graphene in a three-dimensional configuration. With the increase of the number of Si atoms n , the thermodynamic stability of Si n clusters on graphene decreases significantly, the interface binding strength between Si n clusters and graphene decreases, and the charge transfer between Si n clusters and graphene becomes less. At the same time, the storage capacity of Li atoms in Si n /Gr complex is also studied. Li atoms are mainly stored on the graphene surface near Si n clusters and around Si n clusters. The complex synergistic effect of Si n clusters and graphene enhances the thermodynamic stability of Li adsorption. When n ≤ 4, storing two Li atoms is beneficial to improving the thermodynamic stability of x Li-Si n /Gr system, and the thermodynamic stability decreases with the increase of Li atom number. When n ≥ 5, the thermodynamic stability of x Li-Si n /Gr system decreases with the increase of Li atom number. In the x Li-Si 5 /Gr system, the C-C bond and Si-Si bond are mainly covalent bonds, while the Li-C bond and Li-Si bond are mainly ionic bonds with certain covalent properties.