Method for operating a fuel cell, polymer electrolyte membrane fuel cell which works with the method and process for producing the fuel cell

摘要

When operating known polymer electrolyte membrane fuel cells it has to be made sure that the phosphoric acid does not directly contact the metal bipolar plate of the fuel cell at high temperatures. In order to avoid such a contact, a sufficiently electroconducting intermediate layer is interposed between the membrane electrode unit and the bipolar plate of the fuel cell, which prevents the phosphoric acid or a mixture of phosphoric acid and water that may escape from the membrane-electrode unit from reaching the bipolar plate. For producing the fuel cell, at least a two-layer stratified structure is introduced which becomes more hydrophobic and more finely pored with increasing proximity to the bipolar plate.