Changes of Anion Exchange Membrane Properties during Chemical Degradation

Water content plays a major role in the properties of anion-exchange membranes (AEMs) and, therefore, in the AEM fuel cell (AEMFC) performance and performance stability. Characterization of AEMs during membrane degradation is critical in order to understand the membrane behavior during fuel cell operation time. In spite of its importance, the relationship between different membrane properties during chemical degradation has yet to be investigated. In this study, we measure the changes in AEM properties - in particular, ion exchange capacity (IEC), water uptake (WU) and conductivity - during membrane chemical degradation in alkaline medium. To the best of our knowledge, this is the first time this kind of data has been investigated. While all the properties change during AEM degradation, results indicate that membrane WU decreases linearly with decreasing IEC; however, AEM ion-conductivity shows a sigmoidal-like shape relationship with IEC. We introduce a simple model to explain these effects.