Ice Formation in PEM Fuel Cells Operated Isothermally at Sub-Freezing Temperatures

Abstract

The effect of MEA and GDL structure and composition on the performance of single-PEM fuel cells operated isothermally at sub-freezing temperatures is presented. The cell performance and durability are not only dependent on the MEA/GDL materials used but also on their interfaces. An increase in high frequency resistance was observed in certain MEAs where there is a possibility of ice formation between the catalyst layer and GDL leading to a loss in contact area. The total water/ice holding capacity for any MEA was lower at lower temperatures and higher current densities. The durability of MEAs subjected to multiple isothermal starts was better for cloth GDLs when compared to paper GDLs. The ice formation was monitored using high-resolution neutron radiography and was found to be concentrated near the cathode catalyst layer. Finally, there was significant ice formation in the GDLs especially at the higher temperature and lower current density operations.