Numerical simulation of the ordered catalyst layer in cathode of proton exchange membrane fuel cells

A steady-state, one-dimensional numerical model based on cylindrical electrode structure is presented to analyze the performance of the ordered cathode catalyst layer in Proton Exchange Membrane Fuel Cells. The model equations account for the Tafel kinetics of oxygen reduction reaction, proton migration, oxygen diffusion in the cylindrical electrolyte and the gas pores, oxygen distribution at the gas/electrolyte interface. The simulation results reveal that ordered catalyst layers have better performance than conventional catalyst layers due to the improvements of mass transport and the uniformity of the electrochemical reaction rate across the whole width of the catalyst layer. The influences of oxygen diffusivity in gas phase and electrolyte, and the proton conductivity have been shown. The limitation by oxygen diffusion in gas phase drives the active region of the catalyst layer to the catalyst layer/gas diffuser interface. The limitation by proton migration confines the active region of the catalyst layer to the membrane/catalyst layer interface. The limitation due to oxygen diffusion in electrolyte film maintains the uniform distribution of the active region throughout the ordered catalyst layer.