Investigation of Gradient Platinum Loading and Porosity Distribution for Anion Exchange Membrane Fuel Cells

Anion exchange membrane fuel cells (AEMFCs) are in development as a low-cost alternative to proton exchange membrane fuel cells (PEMFCs). AEMFCs produce water at the anode side and consume it at the cathode side, resulting in no cathode water flooding like in PEMFCs. However, it brings complexity to water transportation behavior and requires appropriate water balance to avoid membrane drying out. In this study, a two-dimensional two-phase multi-physics model has been developed to investigate the impacts of three key electrode parameters (porosity, catalyst loading, and ionomer content) that are responsible for water production and transport as well as the performance of an AEMFC. A piecewise constant function along the x-direction (reactant diffusion direction) is used to apply the gradient on the porosity and platinum loading. The present results show that a larger porosity gradient near the cathode gas diffusion layer (GDL)/flow channel interface and lower near the GDL/microporous layer (MPL) interface can enhance mass transport and water removal, which is benefited the AEMFC performance. However, anode GDL porosity gradients show a lower AEMFC performance compared to the cathode porosity gradients. Moreover, it was confirmed that for both electrodes, the performance of AEMFC was significantly dependent on each electrode parameter.