Evaluating the Contribution of Direct vs. Indirect Carbonate Production in Anion Exchange Membrane Fuel Cells

One of the most widely discussed topics in the development of anion exchange membrane fuel cells (AEMFC) is the formation of carbonate/bicarbonate anions at the AEMFC anode. For the hydroxide exchange membrane fuel cell, carbonate formation is considered a poison that reduces electrolyte conductivity during operation, mostly through the formation of bicarbonate. In the carbonate exchange membrane fuel cell, the high selectivity of carbonate is required to enable high electrolyte stability while limiting the formation of bicarbonate anions. In both devices, there are two primary routes through which carbonate anions can be formed: direct electrochemical reduction of O2 and CO2, and the indirect formation of carbonate through the reaction of hydroxide with CO2. These two pathways are shown below