TRIUMF, Vancouver, B.C., Canada , V6T 2A3.
J Am Chem Soc. 2014 Jun 4;136(22):7833-6. doi: 10.1021/ja503066a. Epub 2014 May 25.
β-Detected nuclear spin relaxation of (8)Li(+) 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 α relaxation and was well described by the Vogel-Fulcher-Tammann relation, implying the α 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 α relaxation plays an important role.
β 探测核自旋弛豫的（8）Li(+)已被用于研究锂离子在聚（环氧乙烷）（PEO）薄膜中的微观扩散，其中植入的锂离子浓度极低，并且在玻璃化转变温度以上和以下的很宽温度范围内存在 30wt%LiCF3SO3 的 PEO。Do 等人最近的测量结果[Phys. Rev. Lett. 2013, 111, 018301]发现，Li(+)电导率的温度依赖性与介电α弛豫的温度依赖性相同，并很好地符合 Vogel-Fulcher-Tammann 关系，这意味着α弛豫主导 Li(+)输运过程。相比之下，我们发现两种样品中 Li(+)在高温粘弹相中的跳跃遵循阿仑尼乌斯定律，并且显著依赖于盐含量。我们提出，Li(+)在笼之间的跳跃涉及聚合物的运动，但只有在长程扩散中，α弛豫才起着重要作用。
