Analysis of alkaline exchange membrane fuel cells performance at different operating conditions using DC and AC methods

Membrane electrode assemblies (MEAs) for anion exchange membrane fuel cells (AEMFCs) were manufactured from commercial materials: Pt/C catalyst, A201 AEM and AS4 ionomer by using an industrial mass-production digital printing method. The MEA designs selected are close to those recommended by US Department of Energy, including low loading of platinum on the cathode side (0.2 mg cm⁻²). Polarization curves and electrochemical impedance spectroscopy (EIS) were applied for MEA evaluation in fuel cell conditions with variation of gas humidification and oxygen partial pressure (air vs oxygen). The typical impedance curves recorded at H₂/O₂ gas configuration consist of high- and medium-frequency arcs responsible for hydrogen oxidation and oxygen reduction, respectively. Operation with air as a cathode feed gas resulted in a decrease in AEMFC performance due to possible CO₂ poisoning and mass transfer losses. At the same time, EIS demonstrated formation of a low frequency loop due to diffusion limitations. Despite the low loading of platinum on the cathode (0.2 mg cm⁻²), a peak power density of ∼330 mW cm⁻² was achieved (at 50/50% of RH on anode and cathode), which is substantially higher performance than for AEMFC MEAs tested at similar conditions.