第一性原理研究Ge掺杂对硅烯储锂行为的影响  

First-principles study on the effect of Ge doping on the lithium storage behavior of silicene

作　　者：宋俊 蒋明杰 尚文华 李会洁 周文俊 曾小蔚 SONG Jun;JIANG Mingjie;SHANG Wenhua;LI Huijie;ZHOU Wenjun;ZENG Xiaowei(School of Energy and Power Engineering,Zhenghou University of Light Industry,Zhengzhou 45000,Henan,China;College of Software,Zhengzhou University of Light Industry,Zhengzhou 45000,Henan,China)

机构地区：[1]郑州轻工业大学能源与动力工程学院,河南郑州450000 [2]郑州轻工业大学软件学院,河南郑州450000

出　　处：《储能科学与技术》2024年第4期1293-1301,共9页Energy Storage Science and Technology

基　　金：河南省科技攻关项目(232102240077)。

摘　　要：二维材料硅烯被认为是一种极具潜力的锂电负极材料,然而其难以单独稳定存在,通过元素掺杂可有效提高其结构稳定性。锗(Ge)不仅具有与硅(Si)相同的价电子结构,同时锗烯具有更高的电子电导率,并表现出更好的电化学性能。本工作通过基于密度泛函理论的第一性原理计算研究了Ge掺杂对硅烯储锂行为的影响。分别对Si17Ge的结构稳定性、吸附能力、扩散行为、理论比容量、开路电压和电子电导率等进行了计算和分析,结果表明掺杂Ge后,Si17Ge仍保持着硅烯原有的六角晶格结构,表现出良好的结构稳定性。吸附能和扩散能垒表明Ge的掺杂可提高硅烯对锂的吸附能力以及锂在水平和垂直方向的扩散能力。通过开路电压以及吸附能计算推测Si17Ge最大可吸附18个Li,同时具有高达876.85 mAh/g的理论比容量,与已有的二维材料相比,显示出较高的理论比容量和较低的扩散能垒。态密度分析显示Si17Ge吸附少量锂后,费米能级处的DOS因Li的吸附得到了增强,体系表现出金属性。当Si17Ge吸附较高浓度锂时,Li18Si17Ge的费米能级处出现明显带隙,整个体系从导体变为半导体。本研究将为二维硅基材料以及其他二维材料的设计提供重要的理论指导。Silicene,a two-dimensional material,is a promising anode material for lithium-ion batteries.However,it struggles to exist stably alone.Its structural stability can be effectively improved by elemental doping.Germanium(Ge)not only shares the same valence electron configuration as Silicon(Si),but germanene also boasts higher electronic conductivity and better electrochemical properties.This study investigates the impact of Ge doping on the lithium storage behavior of silicene through first-principles calculations based on density functional theory(DFT).The structural stability,adsorption capacity,diffusion behavior,theoretical specific capacity,open-circuit voltage(OCV),and electronic conductivity of Si17Ge were calculated and analyzed.These results demonstrate that Si17Ge maintains good structural stability after Ge doping without exhibiting structural protrusions,depressions,or planar states.This indicates that Ge doping does not alter the two-dimensional warped structure of silicene,distinguishing it from Ge-doped graphene.The adsorption and diffusion energy barriers indicate that Ge doping enhances the lithium adsorption and diffusion capacity of silicone in horizontal and vertical directions.In the horizontal direction,the diffusion step spans 4.63Åand requires overcoming an energy barrier of 0.18 eV,which is substantially lower than that of Li atoms on graphene(0.31 eV)and silicene(0.22 eV).Conversely,in the vertical direction,the diffusion energy barrier is 1.14 eV,higher than that on the surface,indicating increased difficulty in vertical diffusion of Li atoms in Si17Ge.Nevertheless,this value is lower than the vertical diffusion barrier of Li atoms in pure silicene(1.67 eV)and graphene(10.02 eV).Through OCV and adsorption energy calculations,it is estimated that Si17Ge can adsorb a maximum of 18 Li atoms and has a theoretical specific capacity as high as 876.85 mAh/g.It exhibits a higher theoretical specific capacity and lower diffusion energy barrier than existing two-dimensional materials.Density of sta

关 键 词：第一性原理 硅烯 储锂行为 掺杂 

分 类 号：O469[理学—凝聚态物理]