Nafion content in the catalyst layer of polymer electrolyte fuel cells: effects on structure and performance

The influence of the Nafion content in polymer electrolyte fuel cell (PEFC) gas diffusion electrodes with intermixed ionomer in the catalyst was evaluated. Electrochemical studies were carried out in a 50 cm(2) single cell in H-2/air operation at 70 degreesC. Low platinum loading (0.1 mg cm(2)) electrodes with a Nafion content ranging from 14 to 66 wt% were studied. The performance of PEFC electrodes is affected by the Nafion content and an optimal content of about 33 wt% of ionomer was found. Hg intrusion porosimetry and cyclic voltammetry were carried out to evaluate the pore size distribution and the electrochemical surface area respectively. These data were correlated with single-cell performance. The electrochemical experimental data were analysed using a theoretical equation and the kinetics parameters obtained were related to the catalytic layer structure. (C) 2001 Elsevier Science Ltd. All rights reserved.