Patent ID: 8465880

Claim:
A fuel cell stack including power generation units formed by stacking an even number of electrolyte electrode assemblies and metal separators alternately, the electrolyte electrode assemblies each including an anode, a cathode, and an electrolyte interposed between the anode and the cathode, a fuel gas flow field for supplying a fuel gas to the anode and an oxygen-containing gas flow field for supplying an oxygen-containing gas to the cathode being formed in each of power generation units, the fuel gas flow field and the oxygen-containing gas flow field each having an uneven buffer at least at one of a flow field inlet and a flow field outlet of the fuel gas flow field and the oxygen-containing gas flow field, the power generation units including a first power generation unit and a second power generation unit stacked alternately such that a coolant flow field is formed between the first power generation unit and the second power generation unit, wherein each of the first power generation unit and the second power generation unit includes at least first and second electrolyte electrode assemblies; the first electrolyte electrode assembly is stacked on a first metal separator, a second metal separator is stacked on the first electrolyte electrode assembly, the second electrolyte electrode assembly is stacked on the second metal separator, and a third metal separator is stacked on the second electrolyte electrode assembly, in the first power generation unit, bosses of the first metal separator are in a same phase as bosses of the third metal separator; in the second power generation unit, bosses of the first metal separator are in a same phase as bosses of the third metal separator; and bosses of the first metal separator of the first power generation unit are staggered from the bosses of the first metal separator of the second power generation unit in a direction perpendicular to the stacking direction.