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Two models of the cathode of the proton exchange membrane fuel cell, a pseudohomogeneous film model and an agglomerate model, have been compared. The influence of different parameters on the shape of the polarization curves has been shown. Curves simulated by use of the two models and different values of oxygen permeability, effective conductivity and thickness of the active layer as well as thickness of the Nafion® film surrounding agglomerates have been presented and compared with the experimental results. On the basis of the simulations and the SEM study of the structure of the active catalyst layer it has been concluded that the agglomerate model is a better representation of the active catalyst layer than the pseudohomogeneous film model. [ABSTRACT FROM AUTHOR]

Oxygen and hydrogen permeability through Nafion® 117 membrane and recast Nafion film has been studied by means of gas chromatography at different values of temperature and gas relative humidity. Water uptake from the vapour phase by Nafion® 117 membrane and recast film has been investigated. It has been shown that oxygen and hydrogen permeability increases both with temperature and relative humidity of the gas, but water vapour uptake by both Nafion® 117 membrane and recast film decreased with increasing temperature. SEM studies have been performed on the membrane-electrode assembly obtained by impregnation/hot-pressing and on carbon/Nafion® composite; these have indicated that the active catalyst layer is porous with channels for the gas transport. [ABSTRACT FROM AUTHOR]