Patent ID: 7923169

Claim:
A fuel cell comprising a membrane-electrode assembly and a first metal separator and a second metal separator disposed, respectively, on each side of said membrane-electrode assembly, each of said metal separators defining a fluid passage, said fluid passage defining a reactant gas passage formed at a first, membrane-electrode assembly-opposing surface of said metal separator, a coolant passage formed at a second, opposite surface of said metal separator, a reactant gas manifold fluidly connected to said reactant gas passage and a coolant manifold fluidly connected to said coolant passage, said fuel cell having first and second sides and being adapted to be piled with other fuel cells to construct a stack of fuel cells, wherein said first metal separator includes a rib made from said metal formed thereon so as to surround a portion of said first metal separator where said fluid passage is formed, said rib being adapted to metal-to-metal contact with a metal separator of an adjacent fuel cell to construct a seal for a fluid passage surrounded by said rib, a seal line constructed by said rib extending around said portion of the first metal separator where said fluid passage is formed, wherein said rib is integral with said first metal separator, and said rib protrudes in a direction away from a first side of the fuel cell and said rib has a top portion having a cross-sectional shape in the form of an alternating convex and concave surface, wherein said metal rib is adapted to realize a gasket-less structure between said fuel cell on said first side and a flat surface portion of said adjacent fuel cell, and said rib is located on only said first metal separator protruding away from said first side of said fuel cell, and wherein said rib has a plate thickness to provide elasticity, the plate thickness of said rib being constant and substantially equal to a thickness of each of the first and second separators.