Effect of CO2 on the Alkaline Membrane Fuel Cell

A challenge to the maturation of Alkaline Membrane Fuel Cell (AMFC) is the development of materials and components with suitable thermal, chemical, and mechanical stability that can also provide reasonable functional performance. This is highlighted by the need for stable, conductive anion exchange (AE) membrane and ionomer electrolytes and active non-precious metal catalysts suited to alkaline conditions (1). Among the phenomena affecting the performance and stability of the AMFC are those occurring in the presence of carbon dioxide (CO2). Direct alcohol AMFCs maintains CO2 as an electrochemical oxidation reaction product while the ambient air typically used as an oxidant contains approximately 380 ppm CO2. Because carbonate and bicarbonate can form when CO2 is exposed to an alkaline solution, it is important that we gain a comprehension of both the nature and effects of CO2 on the AMFC. Present studies may be broken down into several categories, which may include the effects of the ionic form on the anion exchange membrane conductivity and stability (2,3), thermodynamic equilibrium (4), and electrochemical kinetics (5-8). This paper details a theoretical examination of the effects of CO2 on the AMFC and components. Conservative transport theory is used to examine the nature of CO2 in the respective AMFC electrodes under equilibrium conditions and the implications this has on the component and overall AMFC performance. Conditions related to oxygen and air oxidants as well as hydrogen and methanol fuels are considered