Low humidification effect on performance of proton exchange membrane fuel cells under high current density conditions

Abstract

To enhance water management in proton exchange membrane fuel cells, the influence of drying and flooding on performance in different voltage ranges is investigated by experiment. The current density attenuates as the voltage decreases in the concentration polarization range. Through the analysis of the performance curves under different conditions, the performance attenuation is due to the high current and overpotential at low voltage, which leads to the temperature rising and drying up. At high flow rates, the current attenuates at low voltages, indicating that the current density attenuation is not because of flooding and insufficient reactants. According to calculations, the anode water content is low due to more protons and water being transferred from anode toward cathode at the high current, which causes the current density to attenuate. From the current ratio, the cell can generate an additional current density of 3.2% at 0.1 V voltage, which can evaluate the degree of carbon corrosion and water electrolyzation due to the insufficient supply of reactants. In addition, the voltage undershoot of switching to high current is great, and the fuel cell has a high demand for water. Finally, reducing temperature and increasing humidification can alleviate the attenuation of current density.