Patent ID: 8911916

Claim:
A fuel cell comprising: a membrane electrode assembly comprising: a solid polymer electrolyte membrane including a first side surface and a second side surface opposite to the first side surface in a stacking direction; a first electrode provided on the first side surface of the solid polymer electrolyte membrane and including an electrode catalyst layer and a gas diffusion layer; a second electrode provided on the second side surface of the solid polymer electrolyte membrane and including an electrode catalyst layer and a gas diffusion layer, an outer dimension of the first electrode being set to be smaller than an outer dimension of the second electrode when viewed from the stacking direction; and a resin frame member provided to surround an outer periphery of the solid polymer electrolyte membrane, the membrane electrode assembly including a power generation section and a stepped section, the power generation section being located in an interior space of the resin frame member, the solid polymer electrolyte membrane being provided between the first electrode and the second electrode in the power generation section, the stepped section being located on an outer side of the first electrode, the solid polymer electrolyte membrane being provided between the second electrode and the resin frame member in the stepped section; a first separator disposed on a first side of the membrane electrode assembly; and a second separator disposed on a second side of the membrane electrode assembly, wherein thicknesses of the membrane electrode assembly, the first separator, and the second separator are provided such that a contact pressure of the power generation section is greater than a contact pressure of the stepped section when the fuel cell is in a clamped and assembled state, wherein the resin frame member includes a frame main body and a thin-walled portion, wherein the frame main body is provided to surround the outer periphery of the solid polymer electrolyte membrane, wherein the thin-walled portion inwardly extends from an inner periphery of the frame main body and is provided to surround an outer periphery of the first electrode, the thin-walled portion having a thickness thinner than a thickness of the frame main body in the stacking direction, wherein the stepped section is composed of the thin-walled portion of the resin frame, the solid polymer electrolyte membrane, and the second electrode, wherein the resin frame member directly contacts the first separator, wherein the resin frame member has no direct contact with the second separator, and wherein a space is provided between the resin frame member and the second separator such that the space extends over a surface of the frame main body to the exterior of the resin frame member, wherein the space provides no direct contact between the resin frame member and the second separator.