Measuring the true hydroxide conductivity of anion exchange membranes

In this study, a CO2-in-situ purging technique was used to measure the true OH‾ conductivity of several anion exchange membranes (AEMs). During this process, membranes are in-situ de-carbonated allowing the AEMs to reach their full OH‾ form, and therefore to measure their highest (true) OH‾ conductivity. The de-carbonation process in all the studied AEMs was also investigated. The time constant of the de-carbonation process τ was calculated and related to the membrane properties as well as to the de-carbonation dynamics. The time constant of the de-carbonation process was found to decrease with increasing current densities and decreasing the IEC of the membranes. This work provides unique and important data crucial to increasing the understanding of the main factors that may mitigate the de-carbonation process in AEMs to allow AEM fuel cells to be operated with ambient air.