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

1、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

2、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

3、摘要】Lattice dyn amical properties of LiFePO4 are studiedusing first-principles density functional theorytaking into account the on-site Coulomb interactionwithin theGGA+U scheme. Born effective charge ten sors, phononfrequencies at the Brillouinzone center and phonon dispersioncurves are calculated a

4、nd an alyzed. The Born effective charge ten sorsexhibit ani sotropy, which gives an in direct evide nee for theone-dimensional Li migration tunnel along the 010 directi on in LiFePO4,which has bee n proposed by other theoretical calculations andexperimental observation. The calculated pho non freque

5、 ncies at therpoint of the Brillo uin zone agree well with the available experime ntalresults.A ntisite defect, electr onic con ductivity and ionic dyn amicproperties of LiFePO4 have bee n inv estigated using first-principlesdensity functional theory taking into accountthe on-site Coulomb in teracti

6、o n within the GGA+U scheme.Results in dicate the Li/Fe excha nge defect is the most preferred tooccur in LiFePO4, which causes the Fe-O bond length to cha nge in thedirecti on favors the formatio n of Li+ diffusi on cha nn els, hence improving the ionic dyn amic properties of the olivi ne LiFePO4.A

7、tomic andelectro nic structures of LiFePO4 with Mg doping at Li and Fe sites havebeen investigatedusingthe first-principles density functional theory with the on-site Coulombinteraction taken into account. It isdem on strated that Mgis prefere ntiallydoped at Fe site in steadof Li site to form a new

8、 LiFe1-yMgyPO4 solid solution,leadingto a higher ionic conductivity. Besides, it is found that formatio n en ergiesand the cell volumes decreased gradually with the in crease of Mgconcen trati on in LiFe1-yMgyPO4, which agrees well with the availableexperimental 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 amicsFirst-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】索购全文在线加好友釣: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 8-291.1锂离子电池发展的历史及其工作原理9-121.2 锂离子电池正极材料的类型和结构12-161.2.1 锂离子电池正极材料的类型 121.2.2 锂离子电池正极材料的结构12-1