Influence of Ionomer Structures and Ratios on Performance and Degradation of PEM Fuel Cells

In recent years, short side chain (SSC) ionomers with lower equivalent weights have been demonstrated to increase cell performance via more-homogenous coating and higher proton conductivity than the conventional ionomer, Nafion, used in the catalyst layer (CL). In spite of some studies on cell performance, the impact of an ionomer's structure and ratio on cell durability has hardly been reported. In this study, a systematic experimental investigation is performed to study the impact of SSC ionomer structures and ratios on fuel cell durability using a scaled up cell (45 cm(2)). A CL fabricated with an SSC ionomer is shown to perform better and be more durable than a CL prepared by Nafion in the same ratio. Moreover, increasing the ionomer ratio in the catalyst layer leads to lower cell performance at high current densities, but higher cell durability. These results highlight the importance of the structure and ratio of the ionomers in cell performance and durability.