Variation of ionic conductivity in a plastic-crystalline mixture.
Variation of ionic conductivity in a plastic-crystalline mixture.
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DOI：
10.1063/1.5001946
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发表时间：
2017-04
期刊：
影响因子：
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通讯作者：
D. Reuter;C. Geiss;P. Lunkenheimer;A. Loidl
中科院分区：
文献类型：
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作者：
D. Reuter;C. Geiss;P. Lunkenheimer;A. Loidl
离子导电塑料晶体（PC）是能量存储设备中固态电解质的可能候选者。有趣的是，大分子与最突出的分子PC电解质琥珀腈的混合物显示出极大地增强其离子电导率。因此，二元混合物似乎是一种很有前途的方式来调整这种固态电解质的导电性。然而，为了阐明塑料晶体中离子电荷传输的一般机制和混合的影响，需要更广泛的数据库。在目前的工作中，我们研究了两个著名的塑料结晶系统，环己醇和环辛醇的混合物，其中1摩尔。%的Li离子。应用差示扫描量热法和介电谱，我们提出了一个彻底的调查相行为和离子和偶极动力学的这个系统。所有的混合物揭示塑性结晶相与相应的取向玻璃化转变。此外，它们的导电性似乎是由“旋转门”机制，这意味着周围的塑料结晶基质的离子平移和分子重取向动力学之间的密切耦合。与基于丁二腈的混合物相反，这种耦合随混合比没有强烈的变化。
Ionically conducting plastic crystals (PCs) are possible candidates for solid-state electrolytes in energy-storage devices. Interestingly, the admixture of larger molecules to the most prominent molecular PC electrolyte, succinonitrile, was shown to drastically enhance its ionic conductivity. Therefore, binary mixtures seem to be a promising way to tune the conductivity of such solid-state electrolytes. However, to elucidate the general mechanisms of ionic charge transport in plastic crystals and the influence of mixing, a much broader database is needed. In the present work, we investigate mixtures of two well-known plastic-crystalline systems, cyclohexanol and cyclooctanol, to which 1 mol. % of Li ions were added. Applying differential scanning calorimetry and dielectric spectroscopy, we present a thorough investigation of the phase behavior and the ionic and dipolar dynamics of this system. All mixtures reveal plastic-crystalline phases with corresponding orientational glass-transitions. Moreover, their conductivity seems to be dominated by the "revolving-door" mechanism, implying a close coupling between the ionic translational and the molecular reorientational dynamics of the surrounding plastic-crystalline matrix. In contrast to succinonitrile-based mixtures, there is no strong variation of this coupling with the mixing ratio.