Fuel cell stack and method of producing the same

1. A fuel cell stack of a flat plate type, comprising a plurality of plate-shaped fuel cells stacked on one another in a stacking direction, each of the plate-shaped fuel cells including an electrolyte layer, an anode disposed on one surface of the electrolyte layer and in contact with fuel gas, and a cathode disposed on the other surface of the electrolyte layer and in contact with oxidant gas, the fuel cells being assembled in a state in which they are pressed in the stacking direction,

the fuel cell stack being characterized in that

at least one of a fuel manifold communicating with a space adjacent to the anode which is a flow passage where the fuel gas comes into contact with the anode and an oxidant manifold communicating with a space adjacent to the cathode which is a flow passage where the oxidant gas comes into contact with the cathode is provided to extend in the stacking direction;

around the at least one manifold of the fuel manifold and the oxidant manifold, the at least one manifold extending in the stacking direction, a compression seal member and a glass seal member are disposed in parallel along a plane in which the corresponding fuel cell extends such that the compression seal member and the glass seal member are sandwiched in the stacking direction between corresponding two of components of the fuel cell stack and surround the at least one manifold;

the compression seal member is disposed surrounding the entire periphery of the at least one manifold;

the glass seal member has a softening point higher than an operating temperature of the fuel cell stack;

the compression seal member is a sheet-shaped member composed of mica or vermiculite which deforms when pressed to thereby form a gas seal,

wherein the compression seal member and the glass seal member are disposed between (i) one of interconnectors and (ii) one of separators, the respective interconnectors serving as a partition between adjacent two of the fuel cells, end plates being disposed at opposite ends of the fuel cell stack in the stacking direction, and the respective separators being joined to the electrolyte layer of the corresponding fuel cell and separating the space adjacent to the anode of the corresponding fuel cell and the space adjacent to the cathode of the corresponding fuel cell,

wherein the separators are formed of metal, and

wherein (i) the one of the separators and (ii) the one of the interconnectors are disposed between the two anodes in the adjacent two of the fuel cells.

2. A fuel cell stack according to claim 1 , wherein the glass seal member has an annular shape and is disposed around the at least one manifold extending in the stacking direction, and the compression seal member is disposed around an outer circumference of the glass seal member.

3. A fuel cell stack according to claim 1 , wherein the compression seal member has an annular shape and is disposed around the at least one manifold extending in the stacking direction, and the glass seal member is disposed around an outer circumference of the compression seal member.

4. A fuel cell stack according to claim 1 , wherein the fuel cell stack is assembled in a state in which it is pressed in the stacking direction as a result of fastening with a bolt.

5. A method of producing a fuel cell stack according to claim 1 , the method comprising:

a first step of disposing the compression seal member and a glass material that later becomes the glass seal member on a common plane such that the compression seal member and the glass material are sandwiched in the stacking direction between corresponding two of the components of the fuel cell stack and surround the at least one of the fuel manifold and the oxidant manifold, the at least one manifold extending in the stacking direction, and the compression seal member is disposed such that the entire periphery of the at least one manifold is surrounded by the compression seal member;

a second step of applying, after the first step, a pressure in the stacking direction of the fuel cell stack to press the compression seal member; and

a third step of performing, after the second step, heating at a temperature equal to or higher than a softening point of the glass material and then cooling to form the glass seal member and to join the glass seal member to corresponding two of the components of the fuel cell stack.

6. A fuel cell stack according to claim 1 , wherein the one of the interconnectors is disposed at an upper side of the one of the separators in the stacking direction.