Experimental Investigation of Proton Exchange Membrane Fuel Cell with Metal Foam Flow Field

Compared with conventional flow field, metal foam has been increasingly used for gas distributor in the PEM (proton exchange membrane) fuel cell due to its high porosity and conductivity, which significantly enhances the species transport under high current density condition. In this study, the cell performances with metal foam and graphite parallel flow field are compared under normal and subzero temperature conditions. Besides, electrochemical impedance spectroscopy (EIS) is recorded to characterize the Ohmic, polarization and polarization resistance. Under normal condition, the cell with metal foam exhibits three times better performance than the one with parallel flow field. Meanwhile, the effects of inlet gas humidity and flow rates on cell performance are also studied, indicating that the cathode flooding easily occurs due to its difficult water removal. However, the high flow rate can greatly ease the cathode water flooding. Under subzero temperature condition, metal foam cell shows higher startup voltage and better ice storage capability. In addition, the effects of start-up temperature and current density on cold start performance of PEM fuel cell are studied and the high frequency resistance (HFR) is also utilized to characterize the water content and ice formation/melting in cell. The experimental results show that low initial water content, high startup temperature, and low startup current density are beneficial to PEM fuel cell cold start performance. Overall, the results shown in this study will facilitate a further understanding of the PEM fuel cell with metal foam flow field.