Anion-exchange membrane (AEM) degradation during fuel cell operation represents the main challenge that hampers the implementation of AEM fuel cells (AEMFCs). Reported degradation values of AEMs are difficult to reproduce as no standard methods are used. The present use of different techniques based on exposure of membranes to aqueous KOH solutions under different conditions and measuring different outputs during time does not allow for a reliable and meaningful comparison of reported degradation data of different AEMs. In this study, we present a practical and reproducible ex-situ technique to measure AEM degradation in conditions that mimic an operando fuel cell environment. In this novel technique, we measure the change of the true hydroxide conductivity of the AEM over time, while exposing it to different relative humidity conditions. The technique does not make use of liquid alkaline solution, thus simulating real fuel cell conditions and providing a good baseline for comparative degradation studies.

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.