Influence of Different Gas Diffusion Layers on the Water Management of the PEFC Cathode

Changes in the performance of polymer electrolyte fuel cells were investigated by studying the material properties of the gas diffusion layer, especially hydrophobicity. The study involved development of a detailed one-dimensional model to measure the differential pressure over anode and cathode and to obtain information about the water content of anode and cathode. The measured differential pressure was found to correlate with the humidification level; this was attributed to the porosity and wetting behaviour of the pores. Measuring the current voltage showed an increase in the loss of performance with rising polytetrafluoroethylene (PTFE) content of the cathode gas diffusion layer. The degree of flooding of the cathode layer was found to be linked with the water transport properties of the cathode diffusion layer, and consequently, with the operating conditions of the cell. 22 refs., 4 tabs., 11 figs.