Understanding the impact of fuel cell anode layer thickness and layer design on reversal tolerance

Membrane electrode assemblies (MEAs) for proton exchange membrane fuel cell (PEMFC) applications must survive fuel starvation events which occur when the flow field becomes blocked by dust/debris/or ice (during freeze events) leading to high (>2 V) potentials at the anode. While most research has focused on optimizing these ‘reversal’ catalysts, recent work has also demonstrated that anode layer thickness/structure has an enormous impact on anode durability. In the present work, the impact of catalyst layer structure is studied in more detail, with a focus on understanding the mechanism for this improvement. The effect of both anode layer thickness as well as the spatial distribution of Ir within the anode layer is evaluated. The longest reversal time is found to result from thin layers, or placing the Ir adjacent to gas diffusion layer (GDL) interface. While both approaches lead to improved reversal times, reducing anode layer thickness is found to be a more promising approach as it results in less degradation during reversal, and is easier to manufacture vs. selectively placing the Ir adjacent to the GDL.