Abstract Accurate measurements of membrane ionic conductivity are important for advancing the fundamental understanding of electric field-driven ion transport in ion-exchange membranes. There is no standardized technique for performing such measurements on membranes equilibrated with salt solutions, despite a longstanding interest in this topic. As a result, discrepancies between reported ionic conductivity values for common commercial membranes are often found in the open literature. This study examines ionic conductivity measurements based on the experimental technique in which a membrane directly contacts the electrodes. In the through-plane configuration of this technique, external resistances due to the interfacial region between the membrane and electrodes contribute significantly to the total measured resistance, particularly for thin membranes equilibrated with dilute salt solutions. A non-invasive approach to account for such external resistances based on performing the measurements with membranes having different thicknesses is presented. The total resistance of the electrochemical cell containing membranes with different thicknesses was measured via electrochemical impedance spectroscopy, and the results were extrapolated to zero thickness to determine the magnitude of the external resistances. The membrane ionic conductivity results obtained from this approach were compared to those obtained from measurements utilizing the in-plane configuration, in which external resistances were negligible, as well as measurements in which external resistances were eliminated by replacing the solution on the membrane surface with a highly conducting electrolyte solution. The salt concentration dependence of the ionic conductivity of homogeneous ion-exchange membranes is discussed within the Nernst-Einstein framework.

中文翻译：

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离子交换膜的离子电导率：测量技术和盐浓度依赖性

摘要 膜离子电导率的准确测量对于促进对离子交换膜中电场驱动离子传输的基本理解非常重要。尽管长期以来对这个主题很感兴趣，但没有标准化技术可以对用盐溶液平衡的膜进行此类测量。因此，在公开文献中经常发现普通商业膜报告的离子电导率值之间存在差异。本研究基于膜直接接触电极的实验技术检查离子电导率测量。在该技术的贯穿平面配置中，由于膜和电极之间的界面区域引起的外部电阻对总测量电阻有显着影响，特别适用于用稀盐溶液平衡的薄膜。提出了一种基于对具有不同厚度的膜进行测量的非侵入性方法来解决这种外部电阻。通过电化学阻抗谱测量包含不同厚度膜的电化学电池的总电阻，并将结果外推至零厚度以确定外部电阻的大小。将从这种方法获得的膜离子电导率结果与使用面内配置测量获得的结果进行比较，其中外部电阻可以忽略不计，以及通过用高导电电解质溶液代替膜表面上的溶液来消除外部电阻的测量。在 Nernst-Einstein 框架内讨论了均质离子交换膜的离子电导率的盐浓度依赖性。