The Effect of Ambient Carbon Dioxide on Anion-Exchange Membrane Fuel Cells

Over the past 10 years, there has been a surge of interest in anion-exchange membrane fuel cells (AEMFCs) as a potentially lower cost alternative to proton-exchange membrane fuel cells (PEMFCs). Recent work has shown that AEMFCs achieve nearly identical performance to that of state-of-the-art PEMFCs; however, much of that data has been collected while feeding CO₂ -free air or pure oxygen to the cathode. Usually, removing CO₂ from the oxidant is done to avoid the detrimental effect of CO₂ on AEMFC performance, through carbonation, whereby CO₂ reacts with the OH^- anions to form HCO₃^- and CO₃^2- . In spite of the crucial importance of this topic for the future development and commercialization of AEMFCs, unfortunately there have been very few investigations devoted to this phenomenon and its effects. Much of the data available is widely spread out and there currently does not exist a resource that researchers in the field, or those looking to enter the field, can use as a reference text that explains the complex influence of CO₂ and HCO₃^- /CO₃^2- on all aspects of AEMFC performance. The purpose of this Review is to summarize the experimental and theoretical work reported to date on the effect of ambient CO₂ on AEMFCs. This systematic Review aims to create a single comprehensive account of what is known regarding how CO₂ behaves in AEMFCs, to date, as well as identify the most important areas for future work in this field.