共掺杂TiO2-B作为可充电锂离子电池负极材料的DFT+U分析

摘要

Passivated co-doped TiO2-B models,with N+V and C+Cr co-doping,were con-structed using multiple cell combination method and the calculation on the models were carried out by first-principles density functional theory.The dopant atoms N+V and C+Cr were in tro-duced into TiO2-B as the candidate for high-performance Li-ion battery cathode material.By cal-culating the embedding site and the activation energy of diffusion path the most stable sites were determined in the co-doped model at low Li+ concentration,the correspondent diffusion activation energies are 0.47,0.42 eV,respectively,for N+V and C+Cr systems.The embedding voltage for N+V model at high-concentration of Li+ is 0.83~0.97 V,is lower than 1.05~1.27 V for C+Cr model,suggesting N+V co-doped TiO2-B is more suitable for Li-ion battery cathode mate-rial.By computing two co-doped materials'density of states(DOS),band gaps are 1.7,1.4 eV, respectively,for N+V and C+Cr models,suggesting N and C mainly modify the structure of va-lence band,while V and Cr mainly modify the structure of conduction band.%采用多元胞组合法构建出钝化共掺杂TiO2-B模型,并引入共掺杂原子N+V和C+Cr,对其进行第一性原理的密度泛函理论(density functional theory,DFT)分析.通过对Li+嵌入位点和迁移活化能的计算,确定了Li+低浓度下共掺杂模型中最稳定的嵌入位点,得出N+V和C+Cr共掺杂体系的迁移活化能分别为0.47,0.42 eV;对Li+高浓度下嵌入电压进行计算,得出N+V共掺杂嵌入电压为0.83~0.97 V,比C+Cr共掺杂的对应值1.05~1.27 V小,因此N+V共掺杂模型更适合用作锂离子电池的负极材料;对两种共掺杂的态密度进行计算,得出N+V和C+Cr共掺杂体系的带隙宽度分别为1.7,1.4 eV,说明N和C主要修饰价带结构,V和Cr主要修饰导带结构.