Polymer electrolyte fuel cell

#This application is the U.S. National Phase under 35 U.S.C. §371 of International Application No. PCT/JP2012/004728, filed on Jul. 25, 2012, which in turn claims the benefit of Japanese Application No. 2011-169236, filed on Aug. 2, 2011, the disclosures of which Applications are incorporated by reference herein.

#The present invention relates to the structure of a polymer electrolyte fuel cell.

#A polymer electrolyte fuel cell (hereinafter referred to as a “PEFC”) causes an electrochemical reaction between a hydrogen-containing fuel gas and an oxygen-containing oxidizing gas, such as air, to generate electric power and heat at the same time. A unit cell (cell) of the PEFC includes a MEA (Membrane-Electrode Assembly), gaskets, and electrically-conductive plate-shaped separators. The MEA is constituted by a polymer electrolyte membrane and a pair of gas diffusion electrodes (an anode and a cathode). The PEFC is commonly formed such that a plurality of cells are stacked, these stacked cells are sandwiched between end plates, and the end plates and the cells are fastened by fastening members (see PTL 1, for example).

#FIG. 1 is a perspective view schematically showing a schematic configuration of a fuel cell stack including a polymer electrolyte fuel cell according to Embodiment 1 of the present invention.

#FIG. 2 is a cross-sectional view schematically showing a schematic configuration of the polymer electrolyte fuel cell of the fuel cell stack shown in FIG. 1.

#FIG. 3 is a front view schematically showing a schematic configuration of an inner surface of a cathode separator of the fuel cell shown in FIG. 2.

#Hereinafter, preferred embodiments of the present invention will be explained in reference to the drawings. In the drawings, the same reference signs are used for the same or corresponding components, and a repetition of the same explanation is avoided. Moreover, in the drawings, only components necessary to explain the present invention are shown, and the other components may be omitted. Further, the present invention is not limited to the embodiments below.

#Embodiment 1

#A polymer electrolyte fuel cell according to Embodiment 1 of the present invention includes: a membrane-electrode assembly including a polymer electrolyte membrane and a pair of electrodes sandwiching the polymer electrolyte membrane; and a pair of separators each formed in a plate shape and having electrical conductivity, wherein: each of the separators includes a peripheral portion and a portion other than the peripheral portion; when viewed from a thickness direction of the separator, the peripheral portion of the separator is formed in an annular shape and is a region located on an inner side of an outer periphery of the separator; and the separator is configured such that a porosity of the peripheral portion is higher than that of the portion other than the peripheral portion.