Membrane electrode assembly with gas diffusion layers having a rib porosity and method of manufacturing the same, as well as fuel cell

A fuel cell comprising:

• a membrane electrode assembly;
• a first separator;
• and
• a second separator,
• wherein the membrane electrode assembly comprises:
• a polymer electrolyte membrane;
• a pair of catalyst layers formed so as to sandwich the polymer electrolyte membrane;
• and
• paired gas diffusion layers that are formed so as to sandwich the pair of catalyst layers and the polymer electrolyte membrane, the paired gas diffusion layers including a first gas diffusion layer and a second gas diffusion layer,
• wherein the first gas diffusion layer is comprised of a porous member mainly comprised of conductive particles and a polymer resin, and is provided with a first main surface and a second main surface positioned on a side opposite to the first main surface, the second main surface being in contact with an adjacent one of the pair of catalyst layers, the first gas diffusion layer including a plurality of longitudinal gas flow passages being formed on a first main surface side of the first gas diffusion layer so as to extend along a length direction of the first gas diffusion layer and so as to be adjacent to one another, and so that a rib portion that separates the mutually adjacent plurality of longitudinal gas flow passages from each other has a porosity that is lower than a porosity of a lower area positioned on a second main surface side below the rib portion, and
• wherein the first separator is placed on the first main surface side of the first gas diffusion layer,
• wherein the first separator includes a first main surface and a second main surface positioned on a side opposite to the first main surface,
• wherein the first main surface of the first separator is in contact with the first main surface of the first gas diffusion layer,
• wherein the first main surface of the first separator includes no gas fluid passage which overlaps with one of the plurality of the longitudinal gas flow passages when seen from a thickness direction of the polymer electrolyte membrane,
• wherein the second separator includes a first main surface and a second main surface positioned on a side opposite to the first main surface,
• wherein the first main surface of the second separator is in contact with the first main surface of the second gas diffusion layer,
• wherein the first main surface of the second separator includes a gas fluid passage, and
• wherein the first main surface of the second gas diffusion layers has no gas fluid passage.