Plate In-Plane Electrical Resistance Impact to Stack Performance

In a cell consisting of composite bipolar plates and a polymer electrolyte membrane a significant cell voltage difference has been measured between the reactant inlet end and the reactant outlet end when the cell is aged or defective. In order to gain further understanding, modeling and experimental studies were conducted simulating the effects of local defects in the MEA. The studies indicate that in the presence of a high local resistance in the MEA or GDL, current bypasses the region creating voltage differences due to high in-plane current. The studies also included incorporating metal plates into the cell with a region of the MEA blocked. In this case, both experimental and modeling results show uniform cell voltage from inlet to outlet. It was concluded that both bipolar plate through-plane electrical resistance and in-plane electrical resistance are important metrics for plate selection and design.