锂离子电池正极材料LiMnPO4的电子结构

摘要

采用基于密度泛函理论的第一性原理计算方法,计算了锂离子电池LiMnPO4正极材料的电子结构.计算结果表明:当Li+嵌入体系后,O和P的原子布居变化较小,电子向金属原子的转移明显得到加强.Li+和O2-有弱相互作用,当Li+离子脱出以后,氧原子所得到的电子数减小,导致布居减小.锂是以离子形式存在的于LiMnPO4正极材料中.在LiMnPO4和MnPO4体系中,Mn原子具有磁性,其磁矩分别为4.78μB和3.84μB,其余原子磁性近似为0.氧为负离子,带负电荷,而P和Mn则为正离子.O2p与P3s、P3p轨道发生有效重叠,并形成共价键,Mn3d和O2p之间能够有效地发生重叠并形成共价键.在放电过程中有电子从外电路进入正极,大部分电子所带电荷分布在Mn原子上.%The electronic structure of LiMnP04 positive electrode material for lithium ion battery was calculated by the first principles method based on the density functional theory (DFT). The calculated results demonstrate that the change for the atomic populations of 0 and P is slight, and the transfer of electrons to the metal atoms is obviously strengthened after the intercalation of Li+ ions. There is a weak interaction between Li+ ions and O2"ions, and the obtained electric charge of oxygen atom reduces, and then the atomic population decreases after deintercalation of Li+ ions. As a result, lithium element exists in the LiMnPO4 positive electrode material mainly in form of ions. In the LiMnP04 and MnP04, Mn atoms have magnetic properties, and the magnetic moment values are 4.78μB and 3.84μB, respectively. However, the magnetic properties of the rest atoms approximate to zero. For oxygen anion, with negative charge, and P and Mn is positive ion. There is an effective overlap between O2p, P3s, P3p orbits and Mn3d, 02p orbits, and then forms the covalent bonds. During the discharge, the electrons enter the positive electrode from external circuit, and most of the electrons mainly fill in the Mn atoms.