Membrane-electrode unit with an integrated wear ring, and method of making the same

A method of making a membrane-electrode unit with an integrated sealing edge for a polymer electrolyte membrane fuel cell, comprising the following steps:

• forming a membrane-electrode layer material made of an anode electrode and a cathode electrode with a polymer electrolyte membrane disposed therebetween;
• severing a piece of the layer material in a size suitable for making a desired membrane-electrode unit, both surfaces of the membrane of said severed piece being covered substantially completely by the electrodes;
• pretreating portions of the electrodes and/or of the membrane on which a sealing edge is to be formed before formation of the sealing edge;
• and
• forming the sealing edge around the periphery of said severed piece by at least one of having a sealing agent penetrate into an edge portion of at least one of the electrodes, the pores of the at least one electrode being filled substantially completely in said edge portion such that the sealing edge penetrates an edge portion of at least one of the electrodes and adheres to the portion of the membrane in contact with the edge portion, and by applying a sealing agent to the end face of at least one of the electrodes and to the end faces of the membrane such the sealing edge adheres to at least the end faces of said membrane;
• wherein said pretreatment consists in wetting the portions of the electrode on which the sealing edge is to be formed, with a solvent of the sealing agent.

A method of making a membrane-electrode unit with an integrated sealing edge for a polymer electrolyte membrane fuel cell, comprising the following steps:

• forming a membrane-electrode layer material made of an anode electrode and a cathode electrode with a polymer electrolyte membrane disposed therebetween;
• severing a piece of the layer material in a size suitable for making a desired membrane-electrode unit, both surfaces of the membrane of said severed piece being covered substantially completely by the electrodes;
• pretreating portions of the electrodes and/or of the membrane on which a sealing edge is to be formed before formation of the sealing edge;
• and
• forming the sealing edge around the periphery of said severed piece by at least one of having a sealing agent penetrate into an edge portion of at least one of the electrodes, the pores of the at least one electrode being filled substantially completely in said edge portion such that the sealing edge penetrates an edge portion of at least one of the electrodes and adheres to the portion of the membrane in contact with the edge portion, and by applying a sealing agent to the end faces of at least one of the electrodes and to the end faces of the membrane such the sealing edge adheres to at least the end faces of said membrane;
• wherein said pretreatment consists of milling portions of the surface of the electrode on which the sealing edge is to be formed.

A method of making a membrane-electrode unit with an integrated sealing edge for a polymer electrolyte membrane fuel cell, comprising the following steps:

• forming a membrane-electrode layer material made of an anode electrode and a cathode electrode with a polymer electrolyte membrane disposed therebetween;
• severing a piece of the layer material in a size suitable for making a desired membrane-electrode unit, both surfaces of the membrane of said severed piece being covered substantially completely by the electrodes;
• pretreating portions of the electrodes and/or of the membrane on which a sealing edge is to be formed before formation of the sealing edge;
• and
• forming a sealing edge around the periphery of said severed piece by at least one of having a sealing agent penetrate into an edge portion of at least one of the electrodes, the pores of the at least one electrode being filled substantially completely in said edge portion such that the sealing edge penetrates an edge portion of at least one of the electrodes and adheres to the portion of the membrane in contact with the edge portion, and by applying a sealing agent to the end face of at least one of the electrodes and to the end faces of the membrane such the sealing edge adheres to at least the end faces of said membrane;
• wherein said pretreatment consists of partial oxidation of the portions of the carbon materials of the electrode on which the sealing edge is to be formed.