Method for manufacturing reinforced membrane electrode assembly and reinforced membrane electrode assembly
The present invention provides a method for manufacturing a membrane electrode assembly which improves the reliability of seal, mechanical strength, and handling ability of a solid polymer type fuel cell. The manufacturing method includes: preparing a membrane electrode assembly which differs in the size of the gas diffusion layers at the anode side and the cathode side; and providing a resin frame at the outer peripheral edge of the membrane electrode assembly by molding; wherein the molding includes the use of a mold that keeps penetration of the resin frame material into the gas diffusion layers and/or electrode layers to a minimum and prevents warping of the outer peripheral edges.
1. A manufacturing method of a reinforced membrane electrode assembly for solid polymer type fuel cell use comprising:
preparing a membrane electrode assembly including
a polymer electrolyte membrane,
a first electrode layer which is provided on one side of said electrolyte membrane,
a first gas diffusion layer which is provided on said first electrode layer on the side opposite to said electrolyte membrane,
a second electrode layer which is provided on the other side of said electrolyte membrane, and
a second gas diffusion layer which is provided on said second electrode layer on the side opposite to said electrolyte membrane;
in which membrane electrode assembly, said first gas diffusion layer and said first electrode layer are arranged on the surface of said electrolyte membrane
so that the outer peripheral edge of said first gas diffusion layer as a whole fits within the range of the outer peripheral edge of said electrolyte membrane and
so that a surface region of said electrolyte membrane remains between the outer peripheral edge of said first electrode layer and the outer peripheral edge of said electrolyte membrane across the entire circumference of the outer peripheral edge of said first electrode layer; and
in which membrane electrode assembly, said second gas diffusion layer is extended up to at least part of the opposite side from said surface region across the entire circumference of the outer peripheral edge of said electrolyte membrane; and
providing, at said membrane electrode assembly, a resin frame by molding
so as to surround all of the outer peripheral edge of said electrolyte membrane and at least the parts of the outer peripheral edges of said first and second gas diffusion layers near said first and second electrode layers, and
so as to fasten at least part of said surface region,
wherein said molding comprises providing a top mold and bottom mold with projections,
said projections partially compressing at least parts of said first and second gas diffusion layers,
said compressed part of said first gas diffusion layer is near the outer peripheral edge of said first gas diffusion layer at a farther position than said compressed part of said second gas diffusion layer as seen from a center part of said membrane electrode assembly;
whereby penetration of said resin frame material to said first gas diffusion layer and/or said first electrode layer is kept to a minimum; and
whereby warping of the outer peripheral edges of said electrolyte membrane, said second electrode layer, and said second gas diffusion layer is prevented.
2. The method as set forth in claim 1 wherein said projections are arranged to compress a part near the outer peripheral edge of said first gas diffusion layer.
3. The method as set forth in claim 1 wherein said projections are arranged in rim edge shapes continuously or discontinuously.