Optimizing membrane pretreatment for improved performance of anion exchange membrane-unitized regenerative fuel cells

Anion exchange membranes (AEMs) play a critical role in anion exchange membrane-unitized regenerative fuel cells (AEM-URFCs). In this study, we investigated the effect of different membrane treatment processes on the performance of AEM-URFCs. By replacing bromide ions (Br-) with hydroxyl ions (OH-), we were able to greatly enhance cell performance. We treated a membrane electrode assembly (MEA) with KOH solutions of varying solvents and concentrations, which caused the AEM to swell and replace Br- ions with OH- ions. We found that the concentration of OH- ions in the KOH solution had a significant impact on Br- ion replacement. The MEA treated with 1.0 M KOH in a mixture of isopropyl alcohol (IPA) and deionized water (H2O) (25/75 vol%) had the lowest Br- ion content and exhibited a current density of 215.0 mA cm(-2) at 0.5 V (fuel cell mode) and 65.0 mA cm(-2) at 2.0 V (water electrolyzer mode). These findings can inform future research on AEM-based fuel cells and water electrolyzers by identifying an optimal membrane pretreatment process.