掺杂的钛基锂电池负极材料的结构与性能的研究

Study on the Structure and Properties of Doped Titanium-Based Lithium Battery Cathode Materials

本文使用基于密度泛函理论(DFT)的超软赝势模拟法来对Li2ZnTi3O8、掺杂后的Li1.9Al0.1ZnTi3O8和Li1.9Ag0.1ZnTi3O8材料进行了电子结构与光学性质的研究。首先用CASTEP子程序对LZTO材料构建超晶胞并进行几何结构优化,并对优化后的电子结构进行计算:包括能带结构、晶格常数、各原子的分波态密度以及总体态密度等。结果表明,LZTO晶格常数为a = b = c = 8.009 Å,Li1.9Al0.1ZnTi3O8晶格常数a = b = c = 8.837 Å,Li1.9Ag0.1ZnTi3O8晶格常数为a = b = c = 8.959 Å,与实验值接近。通过能带结构和态密度图得到Li2ZnTi3O8是一种直接带隙半导体材料,掺杂后电子的能量范围变窄,主要来自于Li、Ag、Zn和Al元素的贡献。最后计算和分析了LZTO的光学性质(光学吸收光谱),以期为锂离子电池电极材料的设计与优化提供理论指导。

In this paper, the electronic structure and optical properties of Li2ZnTi3O8, doped Li1.9Al0.1ZnTi3O8 and Li1.9Ag0.1ZnTi3O8 have been studied by means of ultra-soft pseudopotential simulation based on density functional theory (DFT). Firstly, the supercell of LZTO material was constructed by CASTEP subroutine and the geometric structure was optimized, and the optimized electronic structure was calculated, including band structure, lattice constant, partial wave state density of each atom and total state density. The results show that LZTO lattice constant is a = b = c = 8.009Å, Li1.9Al0.1ZnTi3O8 lattice constant a = b = c = 8.837Å, Li1.9Ag0.1ZnTi3O8 lattice constant is a = b = c = 8.959, which is close to the experimental value. The band structure and state density map show that Li2ZnTi3O8 is a direct band gap semiconductor material, and the energy range of doped electrons is narrowed, mainly from the contributions of Li, Ag, Zn and Al elements. Finally, the optical properties (optical absorption spectra) of LZTO are calculated and analyzed, in order to provide theoretical guidance for the design and optimization of electrode materials for lithium-ion batteries.