【摘要】 由广义梯度近似的密度泛函理论,计算了LiFePO4在Mg掺杂前后的电子结构.结果表明,Fe—O键是较弱的共价键;而P—O键的键级大,键长短,形成的是很强的共价键.掺杂Mg后,键中的共价成分有些减弱.在总态密度中费米能级附近的价带和导带,主要来自于Fe的3d态电子.掺杂物的能隙明显小于纯LiFePO4的能隙,并且掺杂后,发生了红移现象,从而表明掺杂Mg可以提高LiFePO4的导电性能.更多还原

【Abstract】 The electronic structures in pure and Mg-doped LiFePO4 were studied by density functional theory(DFT) based on general gradient approximation(GGA).The results show that Fe—O covalent bond is clearly weaker than P—O covalent bond.The valence and conduction bands around the Fermi level in total DOS are mainly due to the 3d electrons of Fe.Compared with the band gap of 0.56 eV in pure LiFePO4,the dopant possesses a small band gap of 0.397 eV,and the red shift appears after doping,which indicates that the impurities Mg increases electronic conductivity of LiFePO4.更多还原