Improvement in the diffusion characteristics of low Pt-loaded electrodes for PEFCs

Low Pt loading electrodes have been obtained by the direct mixing of electr ocatalyst and Nafion(R) ionomer (for catalyst layer) and by the introductio n of an intermediate hydrophobic carbon layer to optimize gas distribution. The influence of Teflon(R) content in the carbon layer has been studied an d an optimum content of 20 wt% has been found. The behaviour of the improve d electrodes as a function of temperature (70-95 degrees C) and gas (H-2 an d air) pressure (1-5 bar) has been evaluated in a 50 cm(2) single cell. In air operation at 5 bar absolute pressure and 95 degrees C a maximum in the power density of about 450 mW cm(-2) has been obtained.