第一性原理研究:Mg^2+掺杂尖晶石型LiMn2O4的的电子结构

First-Principles Study:the Electron Structure of Mg^2+Doped Spinel LiMn2O4

尖晶石LiMn2O4正极材料是在原有锂电池正极材料LiCoO2、LiNiO2、LiMnO2的基础上研发出来的优选正极材料,它相较于LiCoO2材料价格更加低廉热稳定性加强且安全性能有所提高。采用Mg^2+掺杂LiMn2O4正极材料,利用基于密度泛函理论的第一性原理对LiMg0.5Mn1.5O4晶格常数与能带结构、态密度进行计算与分析。结果表明:新材料LiMg0.5Mn1.5O4的空间群为F4332,掺杂后晶胞参数a明显减小,晶胞体积收缩;掺杂量为0.5时明显比掺杂量0.125时Fermi能量和能量密度高。Mg^2+掺杂能影响LiMn2O4的晶体结构,形成更加稳定的共价键。掺杂量会改变LiMn2O4的空间群影响到结构稳定性,所以掺杂量不宜过大。

Spinel LiMn2O4 cathode material is a preferred cathode material developed on the basis of the original lithium battery cathode materials LiCoO2,LiNiO2 and LiMnO2.Compared with LiCoO2 material,it has lower price,better thermal stability and better safety performance.Mg^2+doped LiMn2O4 anode material is used.Based on the first principle of density functional theory,the lattice constant,energy band structure and state density of LiMg0.5Mn1.5O4 are calculated and analyzed.The results show that the space group of new material LiMg0.5Mn1.5O4 is F4332.After doping,it is found that cell parameter a decreases and cell volume decreases.When the doping amount is 0.5,the Fermi energy and energy density are significantly higher than when the doping amount is 0.125.Mg^2+doping can affect the crystal structure of LiMn2O4 and form a more stable covalent bond.The doping amount change the spatial group of LiMn2O4 and affect the structural stability.So the amount of doping should not be too much.