Patent ID: 8197984

Claim:
A fuel cell stack comprising: a box-shaped casing; and a stack body provided in said box-shaped casing, said stack body being formed by stacking a plurality of unit cells in a stacking direction, said unit cells each including an electrolyte electrode assembly and metal separators sandwiching said electrolyte electrode assembly, said metal separators being corrugated plates, said electrolyte electrode assembly including a pair of electrodes each having a gas diffusion layer and a catalyst layer, and an electrolyte interposed between said electrodes, wherein said casing comprises: end plates provided at opposite ends of said stack body in the stacking direction; a plurality of side plates provided on sides of said stack body; coupling members for coupling adjacent ends of said side plates; and a coupling pin for coupling said end plate and said side plate, wherein each of the corrugated plates includes a plurality of alternating ridges and grooves on one side and a plurality of alternating ridges and grooves on an opposed side, the grooves and ridges being linear and oriented perpendicular to the stacking direction of the fuel cell stack, wherein a ridge on one side of the plate corresponds to a groove on the opposed side of the plate, wherein a coolant flow field is formed between adjacent separators by direct contact of the ridges of one of the adjacent separators with the ridges of the other of the adjacent separators, wherein the corrugated plates include connecting portions extending from one end of a groove to a corresponding end of a ridge to directly connect the ridge to the groove, the connecting portions being both linear and slant such that the connecting portions are neither perpendicular nor parallel to the stacking direction of the fuel cell stack, so that the corrugated plates have elasticity in the stacking direction, wherein terminal plates are provided at opposite ends of said stack body in the stacking direction, and a spatially insulating spacer member for absorbing dimensional variation of the stack body in the stacking direction is interposed between at least one of said terminal plates and said end plate, the fuel cell stack including only a single spatially insulating spacer member at a single end of the fuel cell stack, and a tightening force applied to the fuel cell stack is adjusted by a thickness of the insulating spacer member, wherein the fuel cell stack is free of a spring member between the box-shaped casing and the terminal plates, and outer marginal regions of the metal separators comprise one or more sealing elements, and the sealing elements extend in the stacking direction only a portion of the distance between adjacent separators so that a gap exists between each sealing element and a seal of an adjacent separator.