Experimental and numerical investigations of high-temperature PEM fuel cells under different anode dilution levels and varying temperatures

This work investigates the effect of nitrogen in the anode gas mixture on the performance of HT-PEMFCs using experiments and simulations. It explores four H₂/N₂ ratios (100/0, 80/20, 60/40 and 50/50) at three temperatures (140 °C, 160 °C, 180 °C), and four current densities (0.1 A cm⁻² to 0.4 A cm⁻²). The results demonstrate that N₂ dilution negatively impacts fuel cells performance, but higher temperatures can mitigate this effect. Temperature influences electrochemical impedance spectroscopy, with initial ohmic resistance increase followed by a slight decrease. N₂ dilution effects charge and mass transfer resistances. Current density has minimal impact on ohmic resistance but improves charge transfer resistance, especially at high frequencies. This understanding can optimize fuel cell performance, especially in ammonia-fueled systems with hydrogen and nitrogen mixtures or during anode gas recycling with significant nitrogen crossover.