Ionic Conductivity, Diffusion Coefficients, and Degree of Dissociation in Lithium Electrolytes, Ionic Liquids, and Hydrogel Polyelectrolytes.
Ionic Conductivity, Diffusion Coefficients, and Degree of Dissociation in Lithium Electrolytes, Ionic Liquids, and Hydrogel Polyelectrolytes.
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DOI：
10.1021/acs.jpcb.8b06424
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发表时间：
2018-08
期刊：
影响因子：
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通讯作者：
L. Garrido;I. Aranaz;A. Gallardo;C. García;N. García;E. Benito;J. Guzmán
中科院分区：
文献类型：
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作者：
L. Garrido;I. Aranaz;A. Gallardo;C. García;N. García;E. Benito;J. Guzmán
研究了电解质在具有不同介电和粘弹性的介质中的导电和扩散行为。提出了一种修正模型，用于区分解离和非解离物质对 NMR 确定的扩散系数的贡献。阻抗谱用于测量水介质中的锂盐、非质子溶剂中的离子液体和水凝胶聚电解质的离子电导率。这些系统中感兴趣物质的扩散系数是通过多核脉冲梯度自旋回波 (PGSE) NMR 确定的。使用修订后的模型对结果进行分析。结果表明，电离程度可以直接通过测量不同类型电解质和各种浓度的离子电导率和扩散系数来确定。此外，这些发现支持了关于电解质的原始阿伦尼乌斯假说，并表明不需要完全解离的假设来描述其导电行为。与溶液中相比，在处于或接近溶胀平衡的水凝胶中观察到的电导率降低主要归因于网络结构引起的离子迁移率受阻。
The conductive and diffusional behavior of electrolytes in media with different dielectric and viscoelastic properties is investigated. A revised model to separate the contribution of dissociated and nondissociated species to the diffusion coefficients determined with NMR is proposed. Impedance spectroscopy is used to measure the ionic conductivity of lithium salts in aqueous medium, ionic liquids in aprotic solvents, and hydrogel polyelectrolytes. The diffusion coefficients of the species of interest in those systems are determined with multinuclear pulsed-gradient spin-echo (PGSE) NMR. The results are analyzed using the revised model. It is shown that the degree of ionization could be determined directly from measurements of ionic conductivity and diffusion coefficients in very different types of electrolytes and in a wide range of concentrations. Furthermore, these findings support the original Arrhenius hypothesis about electrolytes and show that the assumption of a complete dissociation is not required to describe their conductive behavior. The reduced conductivity observed in hydrogels, at or near swelling equilibrium, compared to that in solutions could be attributed mainly to the hindered ionic mobility caused by the network structure.