INVESTIGATION OF THE CHANGE OF THE HYDROPHOBIC BEHAVIOR OF ELECTRODES FOR LOW TEMPERATURE FUEL CELLS

Kurzfassung

The electrochemical performance of electrodes for low temperature fuel cells depends not only on the activity of the used catalysts, in particular at higher current densities the transport characteristics become more important. Especially the transport of the water can yield to high losses in the electrochemical performance due to a hindering of the reactants to enter the reaction zone. The transport of the water is mainly determined by the hydrophobic character of electrodes and their components. Due to fuel cell operation the hydrophobic properties of the electrodes can change. Changes of the hydrophobic character yield to a change of the electrochemical characteristic and requires an adaptation of the operation conditions. For the investigation of the hydrophobic character and its change surface science methods are helpful. The change of the hydrophobic character of low temperature fuel cells was investigated in alkaline fuel cells, polymer electrolyte membrane fuel cells and direct methanol fuel cells.