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

Low Pt loading electrodes have been obtained by the direct mixing of electrocatalyst and Nafion(R) ionomer (for catalyst layer) and by the introduction of an intermediate hydrophobic carbon layer to optimize gas distribution. The influence of Teflon(R) content in the carbon layer has been studied and an optimum content of 20 wt% has been found. The behaviour of the improved electrodes as a function of temperature (70-95 degrees C) and gas (H-2 and 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.