Effects of Both Oxygen Permeability and Ion Exchange Capacity for Cathode Ionomers on the Performance and Durability of Polymer Electrolyte Fuel Cells

For the large-scale commercialization of polymer electrolyte fuel cells (PEFCs),it is very important to reduce the amount of Pt by developing highly efficient cathode catalyst layers (CLs) due to the high cost and limited availability of Pt resources. We investigate the effects of high oxygen permeability ionomers and ion exchange capacity (IEC) on the cathode performance and durability of PEFCs. The high oxygen permeability ionomers are expected to increase the flux of oxygen near the Pt surface of the three-phase boundary, which is critical in the case of extremely low Pt loadings. The low Pt loading cathode CLs are prepared from the AB250-supported Pt catalyst. From the current-voltage (I-E) curve measurements, the high oxygen permeability ionomers improve the cathode performance without any adverse effects. During durability testing, the high IEC ionomers lead to increased solubility of Pt and cause severe Pt agglomeration and a large amount of redeposition of Pt particles in the membrane. Based on these results, we propose a strategy of ionomer property selection to improve both cell performance and durability. (C) The Author(s) 2018. Published by ECS.