A multi-layer structured cathode for the PEMFC

Multi-layer structured cathodes for PEMFC were prepared by a spray-drying method to provide more efficient oxygen reduction in the cathode. The catalytic layer is, in general, composed of electrolyte for proton conduction and of Pt/C for both the electrochemical reaction and electron conduction. Although the presence of electrolyte is essential for proton conduction, the electrolyte phase retards the electron conduction through the catalytic layer because the electrolyte is electronically insulating. For the Pt/C part, vice versa is valid. In an attempt to develop a cathode possessing superior properties both in the proton and electron conduction, double catalytic electrolyte-rich and -poor layers were coated on the polymer electrolyte membrane (PEM). Performances of the double layered cathodes were evaluated from the current-voltage (I-V) characteristics of single cells. In addition, pressure drops across the fabricated cathodes were determined by using permeability measuring apparatus. From the experimental results, the rate of electrochemical reaction in the cathode was discussed in terms of proton transport and electronic conduction along with oxygen transport. (C) 2003 Published by Elsevier Science B.V.