Lithium Ion Conduction in LiTi2(PO4)3 and Related Compounds Based on the NASICON Structure: A First-Principles Study
Lithium Ion Conduction in LiTi2(PO4)3 and Related Compounds Based on the NASICON Structure: A First-Principles Study
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DOI：
10.1021/acs.chemmater.5b01582
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发表时间：
2015-07-28
影响因子：
8.6
通讯作者：
Elsaesser, Christian
中科院分区：
文献类型：
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作者：
Lang, Britta;Ziebarth, Benedikt;Elsaesser, Christian
LiTi2(PO4)(3)(LTP)及基于NaZr2(PO4)(3)(NZP)结构的相关材料属于锂离子电池用锂离子导电化合物家族。由于它们具有TiO6八面体和PO4四面体的三维骨架，为移动载流子提供了多个位置，并且在这种结构中结晶了大量可能的化合物，因此它们是一种很有前途的离子导电材料。在这项工作中，我们用密度泛函理论研究了这些化合物的菱面体结构中间隙锂离子和锂空位的迁移势垒。我们的结果表明，在各种三价、四价和五价阳离子X(LXTP)的LIT中，钛原子的取代导致了影响Li迁移率的结构变化。计算的空位迁移激活能在0.29-0.75 eV之间变化，并与结构中LiO6八面体的尺寸有关。对于体相LTP中的间隙迁移，计算得到的激活能约为0.19 eV。然而，Al等三价离子的取代引入了间隙Li离子以进行电荷补偿，但这些额外的Li离子被捕获在三价离子附近。
LiTi2(PO4)(3) (LTP) and related materials based on the structure of NaZr2(PO4)(3) (NZP) belong to a family of Li ion conducting compounds for applications in Li ion batteries. Because of their three-dimensional framework of TiO6 octahedra and PO4 tetrahedra, which provide several positions for mobile charge carriers, and the large number of possible compounds crystallizing in this type of structure, they are promising ion conducting materials. In this work, we investigate the migration barriers for an interstitial Li ion and a Li vacancy in the rhombohedral structure Of these compounds using density functional theory. Our results show that the Substitution of Ti atoms in LIT by a variety of tri-, tetra-, and pentavalent cations X (LXTP) leads to structural changes influencing the Li mobility. The calculated activation energies for migrating vacancies vary between 0.29 and 0.75 eV and are related to the sizes of LiO6 octahedra in the structure. For migrating interstitials in bulk LTP, the calculated activation energy of about 0.19 eV is much lower. However, substitution by trivalent ions like Al introduces interstitial Li ions for charge compensation, but these additional Li ions get trapped near the trivalent ions.