Fuel cell and fuel cell stack

1. A fuel cell comprising:

a pair of interconnectors;

a single cell located between the interconnectors and having an electrolyte layer and electrode layers formed on upper and lower surfaces, respectively, of the electrolyte layer; and

current-collecting members disposed between the electrode layers and the interconnectors, respectively, and adapted to electrically connect the corresponding electrode layers and interconnectors;

the fuel cell being characterized in that

the current-collecting member corresponding to at least one of the electrode layers comprises a connector contact portion in contact with the interconnector, a cell contact portion in contact with the electrode layer of the single cell, a connection portion connecting the connector contact portion and the cell contact portion, and a spacer disposed between the connector contact portion and the cell contact portion;

an end of the spacer located opposite the connection portion recedes from an end of the cell contact portion located opposite the connection portion and from an end of the connector contact portion located opposite the connection portion; and

a material of the spacer is more flexible in a thickness direction than the current-collecting members.

2. A fuel cell according to claim 1 , wherein one of or both of the connector contact portion and the cell contact portion have an inwardly-warped warp end formed at a side opposite the connection portion.

3. A fuel cell according to claim 2 , wherein the warp end is formed through shear deformation which occurs when at least one of the connector contact portion and the cell contact portion is stamped from a metal sheet.

4. A fuel cell according to claim 1 , wherein, as viewed in plane, at least a portion of the current-collecting member opposite the current-collecting member corresponding to the one electrode layer is in contact with the other electrode layer in a region where the spacer is in contact with the cell contact portion and with the connector contact portion.

5. A fuel cell according to claim 1 , wherein an entire region of the spacer as viewed in plane is contained, as viewed in plane, in a region of contact between the cell contact portion and the electrode layer.

6. A fuel cell according to claim 1 , wherein the spacer is of at least one of mica, alumina felt, vermiculite, carbon fiber, silicon carbide fiber, and silica.

7. A fuel cell according to claim 1 , further comprising a tightening member for unitarily tightening a stack of the interconnectors, the single cell, and the current-collecting members, wherein the tightening member and the spacer press the cell contact portion of the current-collecting member against the single cell and the connector contact portion of the current-collecting member against the interconnector.

8. A fuel cell according to claim 7 , wherein the spacer is higher in thermal expansion coefficient in a tightening direction than the tightening member.

9. A fuel cell according to claim 1 , wherein at least one of the current-collecting members is formed of a porous metal, a metal mesh, wire, or a punched metal.

10. A fuel cell according to claim 1 , wherein the cell contact portion of the current-collecting member is joined to a surface of the electrode layer of the single cell.

11. A fuel cell according to claim 1 , wherein the connector contact portion of the current-collecting member is joined to the interconnector.

12. A fuel cell according to claim 1 , wherein the current-collecting member is disposed between the electrode layer corresponding to fuel gas and the interconnector and is formed of Ni or an Ni alloy.

13. A fuel cell stack characterized in that a plurality of the fuel cells according to claim 1 are stacked and fixed together by a tightening member.

14. A fuel cell according to claim 1 , wherein the electrolyte layer assumes a plate-like form.

15. A fuel cell according to claim 2 , wherein the warp end is engaged with an edge of the spacer.