Dynamical Origin of Ionic Conductivity for Li7P3S11 Metastable Crystal As Studied by 6/7Li and 31P Solid-State NMR

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• 作者：Miwa Murakami ; Keiji Shimoda ; Shinya Shiotani ; Akio Mitsui ; Koji Ohara ; Yohei Onodera ; Hajime Arai ; Yoshiharu Uchimoto ; Zempachi Ogumi
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：October 29, 2015
• 年：2015
• 卷：119
• 期：43
• 页码：24248-24254
• 全文大小：330K
• ISSN：1932-7455

文摘

To examine the dynamical origin of high ionic conductivity of (Li₂S)₇₀(P₂S₅)₃₀ glass ceramic obtained by annealing (Li₂S)₇₀(P₂S₅)₃₀ glass, we applied ^6/7Li and ³¹P solid-state NMR. NMR line shapes and spin鈥搇attice relaxation times (T₁) were measured as a function of temperature. The results showed that dynamics of the PS₄ tetrahedra and P₂S₇ ditetrahedra units in (Li₂S)₇₀(P₂S₅)₃₀ glass ceramic is not appreciable at temperatures below ca. 310 K, where the ionic conductivity is low. At higher temperatures, however, significant motion especially for the P₂S₇ ditetrahedra unit is apparent in both of ³¹P-T₁ and ³¹P MAS line shapes. Further, we applied the ³¹P鈥?sup>31P dipolar correlation experiment to examine the ³¹P line width, which is reduced by motion at higher temperatures. It was shown that the line width of the P₂S₇ unit is attributable to the distribution of local structures of and around the P₂S₇ ditetrahedra unit. With these, we concluded that the significant motional fluctuation of the P₂S₇ ditetrahedra unit at above 310 K allows facile diffusive motion of lithium ions, leading to the high ionic conductivity.