摘要
采用原子基表示的第一原理赝势方法 ,计算了正极材料LiMn2 O4的电子结构 ,发现LiMn2 O4的价带主要是由Mn(8)和Mn(9)的 3d轨道和O(7)、O(6 )、O(4 )的 2p轨道构成 ,导带主要是由Mn(8)和Mn(9)的 3d轨道和O(7)的 2 p轨道构成 .通过计算Li5Mn7CoO8的电子结构 ,发现在LiMn2 O4中用钴离子取代 16d位锰离子将使电极材料的费米能减小 ,放电电压降低 ;锂离子的净电荷增大 ,锂离子与氧离子的相互作用增强 ,可逆容量降低 ;同时由于价带宽度变窄 ,Co-O键间的相互作用比Mn -O键间的相互作用强 ,所以 ,结构稳定性增加 ,电极循环性能改善 .
The electronic structures of electrode material LiMn 2O 4 and Li 5Mn 7CoO 8 for the lithium ion battery are studied by employing an ab initio 'atomic-basis+norm-conserving non-local pseudopotentias' method. The calculation results of the electronic structure of anode material LiMn 2O 4 show that the valence band of LiMn 2O 4 are mainly made up of 3d atomic orbits of Mn(8) and Mn(9), and 2p atomic orbits of O(7), O(6) and O(4), while the conduction band contains essentially 3d orbits of Mn(8) and Mn(9), and 2p atomic orbits of O(7). At the same time, the computing results of electronic structure of electrode material Li 5Mn 7CoO 8 indicate that the reversible capacity of the electrode can decrease and discharge voltage reduces in the cycling, and the net charge of partial lithium ions of the active electrode material and the interaction between lithium ions and oxygen ions increase. While the cycling performance of the anode can improve due to the structural stabilization of the material Li 5Mn 7CoO 8 corresponding to the decrease of the valence band width and enhancement of the Co-O bond.
