尾-NMR Measurements of Lithium Ion Transport in Thin Films of Pure and Lithium-Salt-Doped Poly(ethylene oxide)

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• 作者：Iain McKenzie ; Masashi Harada ; Robert F. Kiefl ; C. D. Philip Levy ; W. Andrew MacFarlane ; Gerald D. Morris ; Shin-Ichi Ogata ; Matthew R. Pearson ; Jun Sugiyama
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：June 4, 2014
• 年：2014
• 卷：136
• 期：22
• 页码：7833-7836
• 全文大小：270K
• 年卷期：v.136,no.22(June 4, 2014)
• ISSN：1520-5126

文摘

尾-Detected nuclear spin relaxation of ⁸Li⁺ has been used to study the microscopic diffusion of lithium ions in thin films of poly(ethylene oxide) (PEO), where the implanted lithium ions are present in extremely low concentration, and PEO with 30 wt % LiCF₃SO₃ over a wide range of temperatures both above and below the glass transition temperature. Recent measurements by Do et al. [Phys. Rev. Lett. 2013, 111, 018301] found that the temperature dependence of the Li⁺ conductivity was identical to that of the dielectric 伪 relaxation and was well described by the Vogel鈥揊ulcher鈥揟ammann relation, implying the 伪 relaxation dominates the Li⁺ transport process. In contrast, we find the hopping of Li⁺ in both samples in the high temperature viscoelastic phase follows an Arrhenius law and depends significantly on the salt content. We propose that the hopping of Li⁺ between cages involves motion of the polymer but that it is only for long-range diffusion where the 伪 relaxation plays an important role.