LiFePO4论文：锂离子电池正极材料LiFePO_4及其掺杂改性的第一性原理研究.doc

LiFeP04论文：锂离子电池正极材料 LiFeP0_4及其掺杂改性的第一性原理研究【中文摘要】基于考虑了 Fe-3d电子间的库仑作用U和交换作用 J的GGA+方案,应用第一性原理计算系统研究了 LiFeP04的晶格动力学性质我们计算并分析了玻恩有效电荷张量、 布里渊区中心的声子频率和声子色散曲线玻恩有效电荷张量显示各向异性 ，佐证了LiFeP04中锂离子沿一维通道方向迁移的机理布里渊区中心点声子 频率的计算值和相应的实验结果符合得比较好 应用第一性原理计算系统研究了 LiFeP04的对位缺陷，以及对位缺陷的形成对材料的电导 率和离子扩散速率的影响结果表明,Li/Fe交换缺陷是最容易形成 的,形成缺陷后的Fe-0键变长,扩宽了锂离子传输通道，有利于锂离 子在通道中的扩散，对材料电化学性能的改善起到了一定的作用应 用第一性原理计算系统研究了具有 Mg掺杂Li和Fe位的LiFeP04材 料的原子和电子结构结果显示,Mg更容易掺杂到LiFeP04的Fe位, 进而形成新的LiFe1-yMgyP04固溶体，可以很好地提高LiFeP04的离 子电导率和电子电导率，并由此提出可能的微观导电机理同时,我们 发现随着Mg含量的增加，杂质的形成能和LiFe1-yMgyP04的体积呈现 降低和减小的趋势，这与实验结果符合得比较好。

英文摘要】Lattice dyn amical properties of LiFePO4 are studied using first-principles density functional theorytaking into account the on-site Coulomb interaction within the GGA+U scheme. Born effective charge ten sors, phononfrequencies at the Brillouin zone center and phonon dispersioncurves are calculated and an alyzed. The Born effective charge ten sors exhibit ani sotropy, which gives an in direct evide nee for the one-dimensional Li migration tunnel along the [010] directi on in LiFePO4, which has bee n proposed by other theoretical calculations and experimental observation. The calculated pho non freque ncies at the r point of the Brillo uin zone agree well with the available experime ntal results.A ntisite defect, electr onic con ductivity and ionic dyn amic properties of LiFePO4 have bee n inv estigated using first-principles density functional theory taking into accountthe on-site Coulomb in teractio n within the GGA+U scheme.Results in dicate the Li/Fe excha nge defect is the most preferred to occur in LiFePO4, which causes the Fe-O bond length to cha nge in the directi on favors the formatio n of Li+ diffusi on cha nn els, hence impro ving the ionic dyn amic properties of the olivi ne LiFePO4.Atomic and electro nic structures of LiFePO4 with Mg doping at Li and Fe sites have been investigated usingthe first-principles density functional theory with the on-site Coulomb interaction taken into account. It isdem on strated that Mgis prefere ntially doped at Fe site in steadof Li site to form a new LiFe1-yMgyPO4 solid solution, leadingto a higher ionic conductivity. Besides, it is found that formatio n en ergies and the cell volumes decreased gradually with the in crease of Mg concen trati on in LiFe1-yMgyPO4, which agrees well with the available experimental data.【关键词】LiFePO4对位缺陷Mg掺杂晶格动力学第一性原理 计算【英文关键词】LiFePO4 An tiste defectMg-dop ing Lattice dyn amics First-pr in ciplescalculati ons【目录】锂离子电池正极材料 LiFePO_4及其掺杂改性的第一性 原理研究【备注】索购全文加好友釣:1.39938848同时提供论文写作一对一指导和论文发表委托服务摘要 4-5 Abstract 5 第一章绪论 8-29 1.1锂离子电池发展的历史及其工作原理 9-12 1.2锂离子电池正极材料的类型和结构 12-16 1.2.1锂离子电池正极材料的类型 12 1.2.2 锂离子电池正极材料的结构 12-16 1.3LiFePO_4 材料 16-22 1.3.1 LiFePO_4 的结构特点16-17 1.3.2 LiFePO_4 的优缺点 17 1.3.3 LiFePO_4的制备方法 17-19 1.3.4 LiFePO_4 的改性研究19-221.4本论文的研究目的及意义 22-23参考文献。