Co掺杂对单斜LiMnO_2结构与性能的影响

采用基于密度泛函理论的第一性原理计算方法研究Co掺杂对单斜LiMnO2结构与性能的影响.结果表明:Co掺杂可缩短阴阳离子间的距离、抑制Jahn-Teller畸变、减小材料的绝缘带隙;掺杂体系中Co3+的电子组态为t62geg0,处于非自旋态,Mn3+的电子组态为t23geg1,处于高自旋态,由于过渡金属原子与氧原子间存在较强的共价相互作用,因此该掺杂体系并非理想的离子晶体.

Effects of Co-Doping on the Structures and Properties of Monoclinic LiMnO2

First\|principle calculation based on density functional theory was employed to investigate the effects of Co\|doping in monoclinic LiMnO₂. It was found that Co\|doping shortened the distances between the anions and the cations effectively, suppressed the Jahn\|Teller distortion markedly and decreased the insulating band gap greatly, which respectively enhanced the structural stability of monoclinic LiMnO₂, increased the intercalation voltage, improved the stability during electrochemical cycles, and increased the electrical conductivity. The calculated results also revealed that the Co ion in the doped system was in non\|spin state with an electron configuration of t⁶_2ge⁰_g and a valence of +3, and the Mn ion was in high\|spin state with an electron configuration of t³_2ge¹_g and also a valence of +3, nevertheless there were strong covalent interactions between the transition\|metal ions and the oxygen ions. The doped material is not an ideal ionic crystal.