On the Determination of PEM Fuel Cell Catalyst Layer Resistance from Impedance Measurement in H2/N2 Cells

Impedance measurements of H2/N2 cell for the determination of PEMFC catalyst layer (CL) resistance can exhibit significant deviation from those predicted assuming homogeneous CL structure with uniform resistance and capacitance. Predictions from model with homogeneous structure but distributed resistance and/or capacitance shows deviation from the ideal mid-frequency response (45o line) but expected low-frequency response (vertical line). A distributed model considering agglomerate-type structure shows deviation from ideal mid-frequency response ((45o line) as well as from ideal vertical-line like response at experimentally employed frequencies although a vertical-line response is predicted at frequencies significantly lower than typically accessible in experiments.