Patent ID: 8232021

Claim:
A fuel cell stack comprising an electricity generating unit for generating electrical energy by electrochemically reacting a fuel and an oxidizing agent, the electricity generating unit comprising: a first separator; a second separator; a membrane electrode assembly (MEA) between the first separator and the second separator, each of the first and second separators comprising a channel on a surface facing the MEA, the channel being divided into a plurality of sections by a barrier rib, and a manifold in the surface facing the MEA, the manifold communicating with the channel; and a gasket, positioned at an outer circumference portion of an area where the MEA is positioned, for sealing a space between the first and second separators and for covering an open area of a channel extension area of at least one of the first and second separators where the manifold communicates with the channel, the channel extension area having a single inclined surface extending from an edge of the manifold to an edge of the barrier rib, the gasket being a separable piece from the MEA and having substantially flat sides respectively facing the first separator and the second separator, wherein the gasket comprises a hard material layer and a plurality of soft material layers, the hard material layer having a higher hardness level than that of the soft material layers, and the soft material layers are respectively on opposite sides of the hard material layer, the soft material layers being thinner than the hard material layer.