Generalized flooded agglomerate model for the cathode catalyst layer of a polymer electrolyte membrane fuel cell

► A generalized flooded agglomerate model was developed to account for agglomerate shape. ► The new agglomerate model was coupled to a 2D CFD code for PEMFC performance. ► Agglomerate shape effects were found to be negligible for small agglomerates (<200 nm). ► For larger agglomerates, shape is critical, and the performance scales as surface-to-volume ratio.