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 evalu ated. 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)) elec trodes with a Nafion content ranging from 14 to 66 wt% were studied. The pe rformance of PEFC electrodes is affected by the Nafion content and an optim al content of about 33 wt% of ionomer was found. Hg intrusion porosimetry a nd cyclic voltammetry were carried out to evaluate the pore size distributi on and the electrochemical surface area respectively. These data were corre lated with single-cell performance. The electrochemical experimental data w ere analysed using a theoretical equation and the kinetics parameters obtai ned were related to the catalytic layer structure. (C) 2001 Elsevier Scienc e Ltd. All rights reserved.