VS_(2)作为锂离子电池负极材料的第一性原理研究  

First-principles study of VS2 as anode material for Li-ion batteries

作　　者：周斌 肖事成 王一楠 张晓毓 钟雪 马丹 戴赢 范志强[1] 唐贵平[1] Zhou Bin;Xiao Shi-Cheng;Wang Yi-Nan;Zhang Xiao-Yu;Zhong Xue;Ma Dan;Dai Ying;Fan Zhi-Qiang;Tang Gui-Ping(School of Physics and Electronic Science,Changsha University of Science and Technology,Changsha 410114,China)

机构地区：[1]长沙理工大学物理与电子科学学院,长沙410114

出　　处：《物理学报》2024年第11期110-118,共9页Acta Physica Sinica

基　　金：国家自然科学基金面上项目(批准号:12074046);柔性电子材料基因工程湖南省重点实验室资助的课题。

摘　　要：随着对锂离子电池(LIBs)性能要求的提高,研究开发锂离子电池的新型电极尤显重要.本文采用第一性原理计算研究二硫化钒(VS_(2))作为锂离子电池负极材料的可能性.计算结果表明:VS_(2)具有金属性,费米能级附近的态密度主要来源于钒的3d轨道及硫的3p轨道;Li在VS_(2)单层中优先吸附钒(V)的顶位,Li在VS_(2)表面具有非常好的扩散性,扩散势垒仅为0.20 eV,低于石墨烯,表明Li能够较快地迁移,有利于LIB快速充电-放电过程;VS_(2)机械性能良好,杨氏模量为96.82 N/m,且吸附Li后的杨氏模量与泊松比都未减小,表明VS_(2)在吸附Li以及Li离子扩散迁移过程中,刚性并不会降低;并且计算得到VS_(2)的电池容量(466 mAh/g)比石墨烯更高.研究表明VS_(2)具有出色的导电性能和优异的机械刚性及较高的理论容量,是一种非常有前景的锂离子电池负极材料.With the increase of performance requirements for lithium-ion batteries(LIBs),it is particularly important to study and develop new electrodes for lithium-ion batteries.In this work,a 3×3×1 supercell of VS2 is constructed,and the possibility of using it as an anode material for lithium-ion batteries is study by the first-principles method based on density functional theory.Through the analysis of the energy band diagram,it is found that VS2 has metallic properties.Combining the density of states diagram,the analysis shows that the energy band near the Fermi level of VS2 is contributed by the 3d state of V and the 3p state electrons of S,which means that the conductive properties of VS2 are largely affected by the 3d state of V and the 3p state electrons of S.Of the vacancies,bridge sites,and top sites of lithium adsorbing vanadium(V),the top site has the lowest adsorption energy,indicating that lithium will preferentially adsorb the top site of vanadium(V).Through first-principles molecular dynamics simulations of the top position of adsorbed vanadium(V),it is found that at a temperature of 300 K,the total energy of the system and the magnitude of the total temperature fluctuation can reach a steady state,indicating that lithium can exist at the top position of stably adsorbed vanadium(V).Moreover,the interlayer spacing of the double-layer VS2 reaches 3.67Å,which is larger than the interlayer spacing of graphene.From the top position to the vacancy,its diffusion barrier is only 0.20 eV.Its interlayer spacing is larger than the double-layer graphene’s,and its diffusion barrier is lower than graphene’s,indicating that lithium has very good diffusivity on the VS2 surface,and lithium can migrate quickly on the VS2 surface,which is conducive to the rapid charge-discharge process of LIB.In addition to excellent electrical conductivity,VS2 has good mechanical properties.The calculated Young's modulus is 96.82 N/m,and the Young's modulus and Poisson’s ratio do not decrease after adsorbing lithium,indicating that

关 键 词：锂离子电池 吸附能 第一性原理 

分 类 号：TM9[电气工程—电力电子与电力传动]