卤素
离子电导率
离子键合
热扩散率
扩散
从头算量子化学方法
离子半径
从头算
材料科学
化学
结晶学
化学物理
离子
物理化学
热力学
分子
电解质
物理
有机化学
电极
烷基
作者
Andreas R. Stamminger,Benedikt Ziebarth,Matous Mrovec,Thomas Hammerschmidt,Ralf Drautz
标识
DOI:10.1021/acs.chemmater.9b02047
摘要
Halogenated argyrodites Li6PS5Br, Li6PS5Cl, and Li6PS5I exhibit large differences in the measured Li ionic conductivities. Crystallographic analysis has shown that these differences may be related to occupations of specific Wyckoff sites in different argyrodite types, but detailed understanding of the relationship between the atomic structure and operating diffusion mechanisms is still lacking. In this work, we employed ab initio molecular dynamics simulations to calculate the Li diffusivity for different argyrodite structure types. Our calculations show that the Li diffusivity does not depend implicitly on the type of halogen but is rather governed by the degree of structural disorder. Assuming disordered structures to arise naturally from the ordered structure type by thermally activated antisite defects, we are able to explain the degree of disorder found for the different types of halogens from the calculated defect formation energies. Comparing the calculated formation energies to the ionic radii of the halogen atoms, we find a strong correlation between the radii and energies required for introducing the antisite defects.
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