POLYMER ELECTROLYTE FUEL CELL AND ITS OPERATING METHOD

An output decrease may be caused by the temperature difference between the cells located at the ends and the other cells due to heat dissipation from end plates. This invention provides a polymer electrolyte fuel cell capable of avoiding the voltage decrease of the cells closest to the end plates without affecting the output voltage of the other cells. The polymer electrolyte fuel cell of this invention comprises: a cell stack in which unit cells each comprising a polymer electrolyte membrane and an anode and a cathode sandwiching the electrolyte membrane are stacked with conductive separator plates; a pair of current collector plates and a pair of end plates, both of which sandwich the cell stack; and a coolant flow channel which is formed in a part of the conductive separator plates for cooling the unit cells, wherein the conductive separator plate between at least one of the end plates and the unit cell located closest to the one of the end plates has no coolant flow channel therein.