基于第一原理的Li嵌入路径的计算机模拟

Computer Simulation on Li-Insertion Routes Based on First-Principles

为了研究锂离子电池负极材料InSb的L i嵌入过程,使用基于密度泛函理论的第一原理赝势法,计算了L i离子电池非碳类负极材料InSb在L i嵌入时的125相不同情况下的总能、平衡体积和各相间转换的L i嵌入形成能及相对体积变化等,进而参考电压轮廓实验曲线,筛选出了中间经历两相的最可能的反应路径为L i+In4Sb4→L i1In4Sb4,2L i+L i1In4Sb4→L i3In4Sb4,9L i+L i3In4Sb4→L i12Sb4+4 In;中间经历三相的最可能的反应路径为L i+In4Sb4→L i1In4Sb4,2L i+L i1In4Sb4→L i3In4Sb4,4L i+L i3In4Sb4→L i7In3Sb4+In,5L i+L i7In3Sb4→L i12Sb4+3 In。计算了L i3Sb的晶格常数、总能等,讨论了其能带结构和电子态密度等性质。结果表明:随着L i嵌入到InSb中并生成L i3Sb,其体积略有膨胀,材料发生了由半导体性到金属性又到半导体性的转变。

In order to study the process of Li intercalations in InSb, an Ab initio method with the first-principles pseudo potentials based on the density functional theory was used to calculate the total energies, the equilibrium volumes of Li intercalations in InSb in 125 possible cases, the formation energies and the relative volume changes during the material changed from one phase to another. Comparing with the experimental voltage profile curve, we show that the most favored intercalation route for undergoing two intermediate phase is Li ＋ In4Sb4→Li1 In4Sb4, 2Li ＋ Li1 In4Sb4→Li3In4Sb4, 9Li ＋ Li3In4Sb4→Lil2 Sb4 ＋4In, and the most favored route for undergoing three intermediate is Li ＋ In4Sb4→Li1 In4Sb4, 2Li ＋ Li1In4Sb4→Li3In4Sb4, 4Li ＋ Li3In4Sb4→LiTIn3Sb4 ＋ In, 5Li ＋ LiTIn3Sb4→Lil2Sb4 ＋ 3In. The lattice constant and total energy of Li3Sb was also calculated. The band structures, electronic density of states for Li3Sb were also discussed. The result shows that the volume slightly expands from InSb to Li3Sb. The material changed from semiconducting to metallic then again to semiconducting.