Polymer electrolyte fuel cell

A polymer electrolyte fuel cell comprising:

• a membrane-electrode assembly including a polymer electrolyte membrane and a pair of electrodes sandwiching the polymer electrolyte membrane;
• and
• separators each formed in a plate shape and having electrical conductivity, wherein:
• each of the electrodes includes a gas diffusion layer and a catalyst layer having one main surface contacting the polymer electrolyte membrane and is formed such that an outer periphery thereof is located on an inner side of an outer eriphery of the polymer electrolyte membrane when viewed from a thickness direction of the separator;
• the membrane-electrode assembly is sandwiched between a pair of the separators;
• a reactant gas supply manifold hole and a reactant gas discharge manifold hole are formed on main surfaces of each of the separators so as to penetrate the separator in the thickness direction, and a plurality of groove-like first connection channels connected to the reactant gas supply manifold hole and a plurality of groove-like second connection channels connected to the reactant gas discharge manifold hole are formed on one main surface of each of the separators, the main surface contacting the electrode;
• a plurality of groove-like reactant gas channels each having one end communicating with the first connection channel and the other end communicating with the second connection channel are formed on a main surface of at least one of the separator and the gas diffusion layer;
• and
• in a case where among the plurality of reactant gas channels, a reactant gas channel formed to overlap a peripheral portion of the electrode twice and formed such that a length of a portion overlapping the peripheral portion is a predetermined length or shorter when viewed from the thickness direction of the separator and tracing the reactant gas channel from an upstream end thereof to a downstream end thereof is defined as a first reactant gas channel, and
• among the plurality of reactant gas channels, a reactant gas channel formed to overlap the peripheral portion of the electrode and formed such that a length of a portion overlapping the peripheral portion is longer than the predetermined length when viewed from the thickness direction of the separator and tracing the reactant gas channel from an upstream end thereof to a downstream end thereof is defined as a second reactant gas channel,
• each of the plurality of reactant gas channels is formed such that a flow rate of a reactant gas flowing through the second reactant gas channel is lower than that of the reactant gas flowing through the first reactant gas channel.