Patent ID: 7569301

Claim:
A fuel cell comprising: an electrolyte electrode assembly having a pair of electrodes and an electrolyte interposed between the electrodes; separators stacked with the electrolyte electrode assembly, each separator having a first and second metal plate; a reactant gas supply passage and a reactant gas discharge passage extended through the fuel cell in the stacking direction; a reactant gas inlet buffer on respective surfaces of the first and second metal plates facing a respective one of the electrodes, wherein the reactant gas inlet buffer has bosses; a reactant gas outlet buffer on the respective surfaces of the first and second metal plates facing a respective one of the electrodes, wherein the reactant gas outlet buffer has bosses; a reactant gas flow field between each reactant gas inlet buffer and corresponding reactant gas outlet buffer; a coolant inlet buffer on respective surfaces of the first and second metal plates that are opposite the reactant gas inlet and outlet buffers, wherein the coolant inlet buffer has bosses; a coolant outlet buffer on respective surfaces of the first and second metal plates that are opposite the reactant gas inlet and outlet buffers, wherein the coolant outlet buffer has bosses; a coolant flow field between each coolant inlet buffer and corresponding coolant outlet buffer; and the coolant inlet buffer and the coolant outlet buffer including bosses on each of the first and second metal plates facing away from respective electrodes, wherein each coolant inlet buffer and each coolant outlet buffer overlaps at least one of the reactant gas inlet buffers or reactant gas outlet buffers in the stacking direction, and wherein the bosses of overlapping buffers do not overlap each other in the stacking direction.