Membrane electrode assembly with integrated seal

A membrane electrode assembly with an integrated seal for a solid polymer electrolyte fuel cell, the assembly to be compressed to a nominal thickness by a compressing surface, comprising:

• a membrane electrode subassembly comprising a membrane electrolyte, a porous cathode electrode and a porous anode electrode wherein the membrane electrode subassembly is planar and has two major surfaces;
• and
• an edge seal made of a seal material, the edge seal comprising:
• a) an inboard pad adjacent to the two major surfaces at the edges of the membrane electrode subassembly wherein the pad saturates the pores at the edges of the electrodes around the periphery of the membrane electrode subassembly, and wherein the pad is thicker than the membrane electrode subassembly at least at the edges and the pad thickness is such that the stress on the pad is less than the electrode interface stress limit for the seal material when the assembly is compressed to the nominal thickness;
• b) a flexible coupling adjacent to the inboard pad and the edge of the membrane electrode subassembly wherein the coupling thickness is less than that of the inboard pad and is such that a gap remains between the compressing surface and the coupling when the assembly is compressed to the nominal thickness;
• and
• c) a sealing element adjacent to the flexible coupling wherein the thickness of the sealing element is greater than that of the inboard pad and is such that the sealing element is compressed more than the inboard pad when the assembly is compressed to the nominal thickness;
• wherein the shape of the sealing element is described by two offset circles perpendicular to the major surfaces of the membrane electrode subassembly.