Abstract: A membrane-electrode unit (1) with integrated sealing edge for a polymer electrolyte membrane fuel cell having a polymer electrolyte membrane (2), an anode (3) arranged on one surface of the membrane and a cathode (4) arranged on the other surface of the membrane, is made from a layer material of anode material, cathode material and polymer electrolyte membrane material disposed therebetween, from which pieces of suitable size are severed, with the membrane, in the severed pieces, being covered completely by the electrodes on both of its sides. On the periphery of said piece, a sealing edge (5) is formed such that the sealing edge (5) penetrates an edge portion (6′, 7′) of at least one of the electrodes (3, 4) and adheres to the membrane portion adjacent the edge potion and/or the sealing edge adheres to the end faces of at least one of the electrodes and the end faces of the membrane.

Abstract: Gas diffusion electrodes (1) for polymer electrolyte membrane fuel cells are modified such that the diffusion of water therein is inhibited in comparison with un-modified electrodes. Polymer electrolyte membrane fuel cells with the modified gas diffusion electrodes can be operated, with on the average unchanged operating conditions, without addition of water, since the gas diffusion electrodes do not allow more water to escape than that formed during the reaction of burnable gas and oxidizing agent, and guarantee sufficient membrane moisture.

Abstract: A particularly inexpensive, homogeneous and porous gas diffusion electrode which comprises at least one electrically conductive, hydrophobic and gas-permeable gas diffusion layer, comprising a mechanically stable support material which is impregnated with at least one electrically conductive material having a bulk conductivity of ≧10 mS/cm is produced. The gas diffusion electrode can be coated with a catalytically active layer. The electrodes of the invention are particularly suitable for use in fuel cells and electrolysis cells.

Abstract: A particularly inexpensive, lightweight, homogeneous and porous gas diffusion electrode for polymer electrolyte membrane fuel cells is made in that carbonized carbon fiber nonwoven fabric is coated with a mixture of a soot suspension and a polytetrafluoroethylene suspension and sintered thereafter. The gas diffusion electrode may have a catalytically active layer applied thereto.