Patent ID: 7803492

Claim:
A fuel cell stack comprising: a fuel cell unit including at least first and second electrolyte electrode assemblies and at least first, second, and third metal separators, said first and second electrolyte electrode assemblies each including a pair of electrodes and an electrolyte interposed between said electrodes, said first separator and said second separator sandwiching said first electrolyte electrode assembly, said second separator and said third separator sandwiching said second electrolyte electrode assembly, wherein a plurality of the fuel cell units are stacked together to form the fuel cell stack, wherein said second separator is a single metal plate having a first surface and a second surface opposite the first surface and includes an oxygen-containing gas flow field provided on the first surface of the second separator and a fuel gas flow field provided on the second surface of the second separator; and a positioning mechanism for positioning said first to third separators in alignment with each other, wherein said positioning mechanism includes: a first protruded portion protruding from one surface of said second separator toward said first separator; a second protruded portion protruding from the other surface of said second separator toward said third separator, said first protruded portion and said second protruded portion being made of a resin material, and formed integrally with said second metal separator; a first recess provided on said first separator such that said first protruded portion is fitted to said first recess; and a second recess provided on said third separator such that said second protruded portion is fitted to said second recess, wherein surfaces of said first and second recesses are made of a resin material, and said first and second recesses are formed integrally with said first and third metal separators.