Patent ID: 8309273

Claim:
A polymer electrolyte fuel cell comprising: a membrane-electrode assembly including a polymer electrolyte membrane and a pair of electrodes sandwiching a portion of the polymer electrolyte membrane, the portion being located inwardly of a peripheral portion of the polymer electrolyte membrane; an electrically-conductive first separator having a plate shape, disposed on a first face of the membrane-electrode assembly, and including a groove-like first reactant gas channel having a serpentine configuration and formed on one main surface of the first separator so as to contact one of the electrode; and an electrically-conductive second separator having a plate shape, disposed on a second face of the membrane-electrode assembly, and including a groove-like second reactant gas channel having a serpentine configuration and formed on one main surface of the second separator so as to contact the other one of the electrodes so as to bend, wherein: the first reactant gas channel includes an uppermost stream portion which is a part of the first reactant gas channel between at least a first portion where the first reactant gas channel extending from a first gas inlet first contacts the electrode and a second portion where the first reactant gas channel overlapping the second reactant gas channel first separates from the second reactant gas channel so as not to overlap the second reactant gas channel, when viewed from a thickness direction of the first separator, a width of the uppermost stream portion is smaller than a width of a portion of the first reactant gas channel which is a part of the first reactant gas channel other than the uppermost stream portion of the first reactant gas channel, and a cross-sectional area of the uppermost stream portion of the first reactant gas channel is substantially the same as a cross-sectional area of the part other than the uppermost stream portion of the first reactant gas channel.