Solid oxide fuel cell and inter-connector

1. A solid oxide fuel cell comprising:

a fuel cell body which has a cathode layer, a solid electrolyte layer formed of an oxide, and an anode layer and which has a power generation function; and

an inter-connector which has a base portion and a plurality of projecting portions projecting from the base portion toward the fuel cell body and electrically connected to the fuel cell body and which is integrally formed from a metallic material, wherein

each of the projecting portions has a contour composed of a pair of linear portions which are disposed parallel to each other and each of which includes a straight line, and a pair of curved portions which connect opposite ends of the linear portions;

a cross section of each projecting portion taken along a straight line connecting the centers of the pair of linear portions and perpendicular to the pair of linear portions has a first region whose radius of curvature is 1 to 70 mm, a pair of second regions whose first ends are connected to opposite ends of the first region and whose radius of curvature is 0.1 to 0.5 mm, and a pair of third regions which connect second ends of the second regions to the base portion; and

a cross section of each of the projecting portions taken along a straight line connecting the centers of the pair of curved portions, parallel to the pair of linear portions, and located at the middle between the pair of linear portions, and being perpendicular to a plane on which the pair of linear portions are present, has a region whose radius of curvature is 70 mm to 500 mm.

2. A solid oxide fuel cell according to claim 1 , further comprising a second fuel cell body which has a second cathode layer, a second solid electrolyte layer formed of an oxide, and a second anode layer and which has a power generation function, wherein

the inter-connector further has a plurality of second projecting portions projecting from the base portion toward the second fuel cell body and electrically connected to the second fuel cell body;

each of the second projecting portions has a contour composed of a pair of second linear portions which are disposed parallel to each other and each of which includes a straight line, and a pair of second curved portions which connect opposite ends of the second linear portions; and

a cross section of each second projecting portion taken along a straight line connecting the centers of the pair of second linear portions and perpendicular to the pair of linear portions has a fourth region whose radius of curvature is 1 to 70 mm, a pair of fifth regions whose first ends are connected to opposite ends of the fourth region and whose radius of curvature is 0.1 to 0.5 mm, and a pair of sixth regions which connect second ends of the fifth regions to the base portion.

3. A solid oxide fuel cell comprising:

a fuel cell body which has a cathode layer, a solid electrolyte layer formed of an oxide, and an anode layer and which has a power generation function;

a second fuel cell body which has a second cathode layer, a second solid electrolyte layer formed of an oxide, and a second anode layer and which has a power generation function; and

an inter-connector integrally formed from a metallic material and interposed between the fuel cell body and the second fuel cell body, the inter-connector having a plurality of projecting portions projecting toward the fuel cell body and electrically connected to the fuel cell body, and a plurality of second projecting portions projecting toward the second fuel cell body and electrically connected to the second fuel cell body, wherein

each of the projecting portions and the second projecting portions has a contour composed of a pair of linear portions which are disposed parallel to each other and each of which includes a straight line, and a pair of curved portions which connect opposite ends of the linear portions;

a cross section of each of the projecting portions and the second projecting portions taken along a straight line connecting the centers of the pair of linear portions and perpendicular to the pair of linear portions is divided into a first region whose radius of curvature is 1 to 70 mm, a pair of second regions whose first ends are connected to opposite ends of the first region and whose radius of curvature is 0.1 to 0.5 mm, and a pair of third regions which connect second ends of the second regions to the base portion; and

a cross section of each of the projecting portions and the second projecting portions taken along a straight line connecting the centers of the pair of curved portions, parallel to the pair of linear portions, and located at the middle between the pair of linear portions, and being perpendicular to a plane on which the pair of linear portions are present, has a region whose radius of curvature is 70 mm to 500 mm.

4. A solid oxide fuel cell according to claim 2 , wherein a cross section of each of the projecting portions and the second projecting portions taken along a straight line connecting the centers of the pair of curved portions, parallel to the pair of linear portions, and located at the middle between the pair of linear portions, and being perpendicular to a plane on which the pair of linear portions are present, has a region whose radius of curvature is 70 mm to 500 mm.

5. A solid oxide fuel cell according to claim 1 , wherein the inter-connector is formed from a plate-shaped metallic material through press working.

6. A solid oxide fuel cell according to claim 1 , wherein

the base portion has a flat shape; and

the solid oxide fuel cell further comprises a current collector which is disposed on at least one of the inter-connector and the fuel cell body and which is electrically connected to the base portion.

7. An inter connector which is integrally formed from a metallic material and which has a plurality of projecting portions projecting toward a fuel cell body and electrically connected to the fuel cell body, wherein

each of the projecting portions has a contour composed of a pair of linear portions which are disposed parallel to each other and each of which includes a straight line, and a pair of curved portions which connect opposite ends of the linear portions;

a cross section of each projecting portion taken along a straight line connecting the centers of the pair of linear portions and perpendicular to the pair of linear portions has a first region whose radius of curvature is 1 to 70 mm, a pair of second regions whose first ends are connected to opposite ends of the first region and whose radius of curvature is 0.1 to 0.5 mm, and a pair of third regions which connect second ends of the second regions to the base portion; and

a cross section of each of the projecting portions taken along a straight line connecting the centers of the pair of curved portions, parallel to the pair of linear portions, and located at the middle between the pair of linear portions, and being perpendicular to a plane on which the pair of linear portions are present, has a region whose radius of curvature is 70 mm to 500 mm.

8. A solid oxide fuel cell according to claim 3 , wherein the inter-connector is formed from a plate-shaped metallic material through press working.

9. A solid oxide fuel cell according to claim 3 , wherein

the base portion has a flat shape; and

the solid oxide fuel cell further comprises a current collector which is disposed on at least one of the inter-connector and the fuel cell body and which is electrically connected to the base portion.