JP2021022507A - Fuel battery cell - Google Patents

Abstract

To provide a fuel battery cell that mitigates stress in joint material.SOLUTION: A fuel battery cell includes a fuel battery cell main body 10, a separator 30, and a joint material 110. The separator 30 is configured in a frame shape having an opening portion 32 that exposes an area excluding an outer peripheral edge portion 14 of the fuel battery cell main body 10, and has an inner peripheral edge portion 31 that overlaps with the outer peripheral edge portion 14 of the fuel battery cell main body 10. The joint material 110 joins the outer peripheral edge portion 14 of the fuel battery cell main body 10 and the inner peripheral edge portion 31 of the separator 30. The joint material 110 has a central portion 111, a first protruding portion 112, and a second protruding portion 113. The first protruding portion 112 protrudes from the central portion 111 to the inner peripheral side. The second protruding portion 113 protrudes from the central portion 111 to the outer peripheral side. The ratio of the maximum protruding length L113b of the second protruding portion to the minimum protruding length L113a of the second protruding portion 113 in a direction orthogonal to the lamination direction is not less than 1.01 and not more than 10.0.SELECTED DRAWING: Figure 5

Description

The present invention relates to a fuel cell.

A flat cell stack device in which a plurality of fuel cell cell bodies having a flat plate-shaped solid electrolyte and a fuel electrode and an air electrode provided so as to sandwich the solid electrolyte are laminated is known (for example, Patent Document 1). ). Patent Document 1 discloses that a separator that separates a space in which a fuel gas exists and a space in which an oxidant gas exists is attached to a fuel cell main body using a bonding material.

Japanese Unexamined Patent Publication No. 2014-49324

The fuel cell cell body may be deformed due to a temperature change due to the operation of the cell stack device of Patent Document 1, that is, a thermal cycle. In this case, stress is applied to the joining material that joins the fuel cell body. Therefore, an object of the present invention is to relieve stress in the bonding material.

The present inventor has found that the problem that stress is applied to the joint material is based on the fact that the stress caused by the deformation of the fuel cell body tends to remain on the outer peripheral edge of the joint material.

The fuel cell according to a certain aspect of the present invention includes a fuel cell main body, a separator, and a bonding material. The fuel cell cell body has a solid electrolyte, and a fuel electrode and an air electrode laminated so as to sandwich the solid electrolyte. The separator has a frame shape having an opening that exposes an area excluding the outer peripheral edge of the fuel cell body. Further, the separator has an inner peripheral edge portion that overlaps with the outer peripheral edge portion of the fuel cell main body. The joining material joins the outer peripheral edge of the fuel cell body and the inner peripheral edge of the separator. In the stacking direction view, the outer peripheral edge of the joining material has two sets of stretched portions facing each other and a connecting portion for connecting the stretched portions. At least one stretched portion has a curved portion. The joining material has a central portion, a first protruding portion, and a second protruding portion. The central portion overlaps the fuel cell cell body and the separator in the stacking direction. The first protruding portion protrudes from the central portion toward the inner peripheral side. The second protruding portion protrudes from the central portion toward the outer peripheral side. In the direction orthogonal to the stacking direction, the ratio of the maximum protrusion length of the second protrusion to the minimum protrusion length of the second protrusion is 1.01 or more and 10.0 or less.

According to this configuration, the outer peripheral edge of the joining material has a curved portion. The ratio of the maximum protruding length of the second protruding portion to the minimum protruding length of the second protruding portion of the joint material is 1.01 or more and 10.0 or less. Therefore, the stress remaining on the outer peripheral edge of the bonding material is dispersed, and the concentration of stress is easily suppressed. Therefore, the stress in the joint material can be relaxed.

Preferably, the ratio of the maximum protrusion length of the second protrusion to the width of the center is 0.1 or more and 3 or less.

Preferably, the second protrusion is in contact with the side surface of the fuel cell body. The ratio of the thickness of the second protruding portion in contact with the side surface of the fuel cell body to the thickness of the central portion between the separator and the fuel cell body is 0.02 or more and 5 or less.

Preferably, the porosity of the second protrusion is greater than the porosity of the central portion between the separator and the fuel cell body.

Preferably, the ratio of the exposed length of the second protrusion to the thickness of the central portion between the separator and the fuel cell body is more than 1 and 10 or less.

According to the present invention, the stress in the bonding material can be relieved.

Perspective view of the cell stack device. Sectional drawing of the cell stack device. Enlarged sectional view of the cell stack. An enlarged cross-sectional view showing the vicinity of the joint material. Top view of the joint material. The plan view of the joining material which concerns on a modification. The plan view of the joining material which concerns on a modification. An enlarged cross-sectional view showing the vicinity of the joint material according to the modified example. An enlarged cross-sectional view showing the vicinity of the joint material according to the modified example. An enlarged cross-sectional view showing the vicinity of the joint material according to the modified example. An enlarged cross-sectional view showing the vicinity of the joint material according to the modified example. An enlarged cross-sectional view showing the vicinity of the joint material according to the modified example. An enlarged cross-sectional view showing the vicinity of the joint material according to the modified example.

Hereinafter, embodiments of the cell stack device according to the present invention will be described with reference to the drawings.

As shown in FIGS. 1 and 2, the cell stack device 1 includes a fuel cell and fastening members 21 to 28. The fuel cell includes a fuel cell main body 10, a separator 30, and a first bonding material 110. The cell stack device 1 has a structure in which a plurality of fuel cell cells are stacked. That is, the cell stack device 1 has a so-called flat cell stack structure.

The fastening members 21 to 28 fasten a plurality of fuel cell cells. The four fastening members are formed with flow paths through which the oxidant gas or the fuel gas flows along the stacking direction (z-axis). In the present embodiment, the fastening member 23 is used as a fuel gas supply pipe, the fastening member 27 is used as a fuel gas discharge pipe, the fastening member 25 is used as an oxidant gas supply pipe, and the fastening member 21 is used as an oxidant gas discharge pipe. Used as a tube.

[Fuel cell body]
As shown in FIGS. 2 and 3, the fuel cell main body 10 has a solid electrolyte 11, an air electrode 12, and a fuel electrode 13. In the present specification, the direction in which each layer of the solid electrolyte 11, the air electrode 12, and the fuel electrode 13 is laminated is referred to as a lamination direction. The stacking direction is orthogonal to the main surface of each layer. The stacking direction of this embodiment is the z-axis direction. The fuel cell main body 10 has a rectangular shape in a stacking direction view, that is, a plan view (z-axis direction view). The fuel cell main body 10 is configured as a solid oxide fuel cell.

The solid electrolyte 11 has a flat plate shape, and the main surface faces the stacking direction. The air electrode 12 is arranged on one main surface of the solid electrolyte 11. The fuel electrode 13 is arranged on the other main surface of the solid electrolyte 11. That is, the solid electrolyte 11 is sandwiched between the air electrode 12 and the fuel electrode 13. The air pole 12 and the fuel pole 13 have a flat plate shape, and the main surfaces thereof face the stacking direction. In the present embodiment, the air electrode 12 is arranged on the upper surface of the solid electrolyte 11, and the fuel electrode 13 is arranged on the lower surface of the solid electrolyte 11.

The fuel cell body 10 extends in a direction (y-axis direction) orthogonal to the stacking direction. The thickness (dimension in the z-axis direction) of the fuel cell body 10 is substantially uniform throughout. For example, the thickness of the fuel cell body 10 is about 100 to 2100 μm. In this embodiment, the fuel electrode 13 is thicker than each of the solid electrolyte 11 and the air electrode 12. Therefore, the fuel electrode 13 is configured to support the solid electrolyte 11 and the air electrode 12.

The solid electrolyte 11 is composed of a dense material containing, for example, YSZ (yttria-stabilized zirconia). The porosity of the solid electrolyte 11 is, for example, 0 to 10%. The solid electrolyte 11 may be made of a porous material such as GDC (gadolinium-doped ceria). The thickness of the solid electrolyte 11 is, for example, 1 to 50 μm. The coefficient of thermal expansion of the solid electrolyte 11 is, for example, 9 to 11 ppm / K.

The air electrode 12 is made of a porous material containing, for example, LSM (La (Sr) MnO ₃ : lanthanum strontium manganite), LSCF ((La, Sr) (Co, Fe) O ₃ : lanthanum strontium cobalt ferrite) and the like. Will be done. The porosity of the air electrode 12 is, for example, 15 to 55%. The thickness of the air electrode 12 is, for example, 50 to 200 μm. The coefficient of thermal expansion of the air electrode 12 is, for example, 11 to 17 ppm / K.

The fuel electrode 13 has a fuel electrode substrate 131 and a fuel electrode active portion 132. The fuel electrode active portion 132 is arranged on the fuel electrode substrate 131. The dimension in the direction orthogonal to the stacking direction of the fuel electrode substrate 131 is larger than that of the fuel electrode active portion 132. The entire fuel electrode active portion 132 is covered with the solid electrolyte 11. The outer peripheral portion of the fuel electrode substrate 131 is exposed from the fuel electrode active portion 132 and the solid electrolyte 11.

The fuel electrode substrate 131 is made of, for example, a porous material containing Ni and YSZ. The porosity of the fuel electrode substrate 131 is, for example, 15 to 55%. The thickness of the fuel electrode substrate 131 is, for example, 50 to 2000 μm. The coefficient of thermal expansion of the fuel electrode substrate 131 is, for example, 11 to 14 ppm / K.

The fuel electrode active portion 132 is made of, for example, a porous material containing Ni and YSZ. The porosity of the fuel electrode active portion 132 is, for example, 15 to 55%. The thickness of the fuel electrode active portion 132 is, for example, 5 to 100 μm. The coefficient of thermal expansion of the fuel electrode active portion 132 is, for example, 11 to 14 ppm / K.

The fuel cell main body 10 may further include an anti-reaction film (not shown) arranged between the solid electrolyte 11 and the air electrode 12. The anti-reaction film causes a phenomenon in which the material constituting the solid electrolyte 11 and the material constituting the air electrode 12 react with each other to form a reaction layer having a large electric resistance at the interface between the solid electrolyte 11 and the air electrode 12. It is provided to suppress it. The anti-reaction membrane is composed of, for example, GDC. The porosity of the anti-reaction membrane is, for example, 10 to 30%. The thickness of the anti-reaction membrane is, for example, 3 to 50 μm.

[Separator]
As shown in FIGS. 2 to 4, the separator 30 is connected to the fuel cell main body 10. Specifically, the separator 30 is bonded to the solid electrolyte 11 by the first bonding material 110. The separator 30 separates the space through which the fuel gas flows and the space through which the oxidant gas flows. The separator 30 has a function of preventing mixing of the oxidant gas and the fuel gas.

FIG. 5 is a plan view of the first joining material 110, which will be described later. In FIG. 5, the fuel cell main body 10 and the separator 30 are shown by virtual lines. As shown in the virtual line of FIG. 5, the separator 30 has a frame shape having an opening 32. That is, the separator 30 is a continuous one-piece ring. The opening 32 exposes a region of the fuel cell body 10 excluding the outer peripheral edge 14. In the present specification, the central side of the opening 32 is referred to as an inner peripheral side, and the opposite side thereof is referred to as an outer peripheral side.

The separator 30 has main surfaces facing each other. The main surface is a surface extending along the extending direction of the separator 30.

The separator 30 is made of, for example, metal. The separator 30 is preferably made of a ferritic stainless steel, an austenitic stainless steel, or a Ni-based heat-resistant alloy (for example, Inconel 600 and Hastelloy). The thickness of the separator 30 can be, for example, 10 to 1000 μm. The coefficient of thermal expansion of the separator 30 can be, for example, about 11 to 18 ppm / K.

As shown in FIGS. 2 and 3, the separator 30 has a curved portion. The separator 30 of the present embodiment has a shape that is entirely curved. Specifically, the separator 30 is curved so as to move away from the fuel cell body 10 toward the outer peripheral side.

The separator 30 has an inner peripheral edge portion 31 that overlaps with the outer peripheral edge portion 14 of the fuel cell main body 10. The inner peripheral edge portion 31 is joined by the first joining member 110. The inner peripheral edge portion 31 has a frame shape. The inner peripheral edge portion 31 will be described later.

[Interconnector]
As shown in FIGS. 2 and 3, the interconnector 40 ensures continuity between the fuel cell main bodies 10. Further, the interconnector 40 prevents gas from being mixed between the fuel cell main bodies 10. The interconnector 40 has a plate shape and extends in the x-axis direction and the y-axis direction. The interconnector 40 is made of, for example, metal.

As shown in FIG. 2, a holding plate 41 may be arranged on the uppermost layer and the lowermost layer instead of the interconnector 40.

[Current collector]
The current collector 50 ensures continuity between the air pole 12 and the fuel pole 13 of the fuel cell main body 10 and the interconnector 40. The current collector 50 is, for example, a plurality of protrusions protruding from the interconnector 40 toward the air electrode 12. Further, the current collector 50 is, for example, a plurality of protrusions protruding from the interconnector 40 toward the fuel electrode 13. The protrusions are spaced apart from each other. A gas flow path is formed between the protrusions. For example, the current collectors 50 are arranged at intervals in the y-axis direction and extend in the x-axis direction. The current collector 50 is made of, for example, metal.

[First joint material]
As shown in FIGS. 3 to 5, the first bonding material 110 joins the outer peripheral edge portion 14 of the fuel cell main body 10 and the inner peripheral edge portion 31 of the separator 30. The first bonding material 110 of the present embodiment joins the outer peripheral edge portion 14 of the solid electrolyte 11 and the fuel electrode 13 and the inner peripheral edge portion 31 of the separator 30. The first bonding material 110 is in contact with the fuel gas and the oxidant gas.

As shown in FIG. 5, the first joining material 110 has a frame shape. That is, the first bonding material 110 is a continuous integral ring shape and has an opening 110a. As shown in FIGS. 3 and 4, the surface 114 of the first bonding material 110 is curved.

The first bonding material 110 is arranged between the fuel cell main body 10 and the separator 30. As shown in FIGS. 4 and 5, the first joining member 110 has a central portion 111, a first protruding portion 112, and a second protruding portion 113.

The central portion 111 overlaps with the fuel cell main body 10 and the separator 30 in the stacking direction (z-axis direction). The central portion 111 of the present embodiment has an inner peripheral edge portion 31 of the separator 30 embedded therein. That is, the central portion 111 is arranged on the upper side and the lower side in the stacking direction of the separator 30. Further, the central portion 111 is not located below the fuel cell main body 10 in the stacking direction.

The first projecting portion 112 projects from the central portion 111 toward the inner peripheral side. The first protruding portion 112 overlaps with the fuel cell main body 10 and does not overlap with the separator 30 in the stacking direction. The first protruding portion 112 of the present embodiment is not located above the separator 30 in the stacking direction.

The second projecting portion 113 projects from the central portion 111 toward the outer peripheral side. The second protruding portion 113 overlaps with the separator 30 and does not overlap with the fuel cell main body 10 in the stacking direction. The second protruding portion 113 of the present embodiment is not located below the fuel cell main body 10 in the stacking direction.

As shown in FIGS. 4 and 5, the first joining member 110 has an inner peripheral edge 115 and an outer peripheral edge 116. The inner peripheral edge 115 defines the opening 110a. The inner peripheral edge 115 is the inner peripheral edge of the surface of the first joining material 110 that comes into contact with the fuel cell body 10. The inner peripheral edge 115 of the present embodiment is included in the first protruding portion 112.

As shown in FIG. 5, the inner peripheral edge 115 has a substantially rectangular shape in the stacking direction. The inner peripheral edge 115 has two sets of extending portions facing each other and a connecting portion connecting each extending portion. A region excluding the outer peripheral edge portion 14 of the fuel cell main body 10 is located between the two sets of extended portions. Therefore, the two sets of extending portions face each other via the fuel cell main body 10. At least one stretched portion has a curved portion. The entire circumference of the inner peripheral edge 115 of the present embodiment has a curved shape.

Specifically, the inner peripheral edge 115 has first to fourth extending portions 115a to 115d and first to fourth connecting portions 115e to 115h. The first and second stretched portions 115a and 115b face each other. The third and fourth stretched portions 115c and 115d face each other. The first connecting portion 115e connects the first and third extending portions 115a and 115c. The second connecting portion 115f connects the third and second extending portions 115c and 115b. The third connecting portion 115g connects the second and fourth stretching portions 115b and 115d. The fourth connecting portion 115h connects the fourth and first extending portions 115d and 115a. The first to fourth stretched portions 115a to 115d correspond to the sides of the rectangle. The first to fourth connecting portions 115e to 115h correspond to the corner portions of the rectangle.

At least one of the first to fourth stretched portions 115a to 115d has a curved portion. In the present embodiment, each of the first to fourth stretched portions 115a to 115d has a curved portion. Further, each of the first to fourth stretched portions 115a to 115d is curved so as to be separated from the separator 30. Further, the entire first to fourth stretched portions 115a to 115d are curved lines.

The curved portion of the present embodiment is located at the central portion of each of the first to fourth stretched portions 115a to 115d. The central portion is a region located in the center when each of the first to fourth stretched portions 115a to 115d is divided into three equal parts in the extending direction in the stacking direction view.

The curved portion has an inflection point. The inflection point is a point where the bending direction changes in the curved portion. The inflection point of the present embodiment is a point where the maximum protrusion length L112b of the first protrusion 112 is obtained. The inflection point is located at the center of each of the first to fourth stretched portions 115a to 115d.

Each of the first to fourth connecting portions 115e to 115h has an R shape. That is, each of the first to fourth connecting portions 115e to 115h is curved in an arc shape in the stacking direction view. Each of the first to fourth connecting portions 115e to 115h is curved so as to approach the separator 30.

The outer peripheral edge 116 is the outer peripheral edge of the first joining member 110. The outer peripheral edge 116 of the present embodiment is included in the second protruding portion 113. Further, the outer peripheral edge 116 is not in contact with the separator 30 and the fuel cell body 10.

The outer peripheral edge 116 has a substantially rectangular shape in the stacking direction. Specifically, the outer peripheral edge 116 has fifth to eighth extending portions 116a to 116d and fifth to eighth connecting portions 116e to 116h. The fifth and sixth stretched portions 116a and 116b face each other. The seventh and eighth stretched portions 116c and 116d face each other. The fifth connecting portion 116e connects the fifth and seventh extending portions 116a and 116c. The sixth connecting portion 115f connects the seventh and sixth extending portions 116c and 116b. The seventh connecting portion 116g connects the sixth and eighth stretching portions 116b and 116d. The eighth connecting portion 116h connects the eighth and fifth extending portions 116d and 116a. The fifth to eighth stretched portions 116a to 116d correspond to the sides of the rectangle. The fifth to eighth connecting portions 116e to 116h correspond to the corner portions of the rectangle.

At least one of the fifth to eighth stretched portions 116a to 116d has a curved portion. In the present embodiment, the fifth to eighth stretched portions 116a to 116d are curved so as to be separated from the fuel cell main body 10. Further, the entire 5th to 8th stretched portions 116a to 116d are curved lines.

Each of the fifth to eighth connecting portions 116e to 116h has an R shape. That is, each of the 5th to 8th connecting portions 116e to 116h is curved in an arc shape in the stacking direction view. Each of the fifth to eighth connecting portions 116e to 116h is curved so as to be separated from the fuel cell main body 10. The first to fourth connecting portions 115e to 115h and the fifth to eighth connecting portions 116e to 116h are curved in the same direction.

The protrusion length L112 of the first protrusion 112 and the protrusion length L113 of the second protrusion 113 are not constant in the direction orthogonal to the stacking direction. The protruding length L112 of the first protruding portion 112 is a distance that protrudes from the inner peripheral end edge 33 of the separator 30 toward the inner peripheral side in the first joining member 110. The protruding length L113 of the second protruding portion 113 is a distance of the first joining material 110 that protrudes from the outer peripheral edge of the fuel cell main body 10 to the outer peripheral side. The width L111 of the central portion 111 is substantially constant in the direction orthogonal to the stacking direction. The width L111 of the central portion 111 is a distance extending between the outer peripheral edge of the fuel cell main body 10 and the inner peripheral edge 33 of the separator 30. The width L111, the protruding length L112, and the width L113 are distances in the direction from the inner peripheral side to the outer peripheral side in the stacking direction view.

Specifically, as shown in FIG. 5, the ratio (L112b / L112a) of the maximum protrusion length L112b of the first protrusion 112 to the minimum protrusion length L112a of the first protrusion 112 is preferably 1.01. It is 10.0 or more, more preferably 1.10 or more and 8.00 or less. When the ratio (L112b / L112a) is 1.01 or more and 10.0 or less, the stress remaining on the inner peripheral edge of the first bonding material 110 is dispersed, and the concentration of stress is easily suppressed. The ratio (L112b / L112a) is specified by the minimum protruding length L112a and the maximum protruding length L112b measured from the cross section in the stacking direction shown in FIG. 4 in one stretched portion having a curved portion.

The ratio (L113b / L113a) of the maximum protrusion length L113b of the second protrusion 113 to the minimum protrusion length L113a of the second protrusion 113 is preferably 1.01 or more and 10.0 or less, and more preferably 1. .10 or more and 8.00 or less. When the ratio (L113b / L113a) is 1.01 or more and 10.0 or less, the stress remaining on the outer peripheral edge of the first bonding material 110 is dispersed, and the concentration of stress is easily suppressed. The ratio (L113b / L113a) is specified by the minimum protruding length L113a and the maximum protruding length L113b measured from the cross section in the stacking direction shown in FIG. 4 in one stretched portion having a curved portion.

As shown in FIG. 4, the ratio (L112b / L111) of the maximum protruding length L112b of the first protruding portion 112 to the width L111 of the central portion L111 is 0.1 or more and 3 or less. When the ratio (L112a / L111) is 0.1 or more and 3 or less, the stress distribution effect of the first protruding portion 112 can be obtained while ensuring the joint strength between the fuel cell main body 10 and the separator 30. That is, since the stress generated due to insufficient bonding strength between the fuel cell body 10 and the separator 30 can be reduced and the stress dispersion effect of the first protruding portion 112 can be obtained, the first bonding material 110 It becomes easier to suppress the concentration of stress on the inner peripheral edge of the. The ratio (L112b / L111) is specified by the width L111 and the maximum protrusion length L112b measured from the cross section in the stacking direction shown in FIG. 4 in one stretched portion having a curved portion.

The ratio (L113b / L111) of the maximum protruding length L113b of the second protruding portion 113 to the width L111 of the central portion 111 is 0.1 or more and 3 or less. When the ratio (L113b / L111) is 0.1 or more and 3 or less, the stress distribution effect of the second protruding portion 113 can be obtained while ensuring the joint strength between the fuel cell main body 10 and the separator 30. That is, since the stress generated due to insufficient bonding strength between the fuel cell body 10 and the separator 30 can be reduced and the stress dispersion effect of the second protruding portion 113 can be obtained, the first bonding material 110 It becomes easier to suppress the concentration of stress on the outer peripheral edge of the. The ratio (L113b / L111) is specified by the width L111 and the maximum protrusion length L113b measured from the cross section in the stacking direction shown in FIG. 4 in one stretched portion having a curved portion.

The central portion 111 is in contact with the fuel cell main body 10 and the separator 30. Specifically, the central portion 111 is in contact with the fuel electrode 13 of the fuel cell main body 10 and the inner peripheral edge portion 31 of the separator 30. The ratio (L112b / H111) of the maximum protruding length L112b of the first protruding portion 112 to the thickness H111 of the central portion 111 between the separator 20 and the fuel cell main body 10 is 2.0 or more and 150 or less. When the ratio (L112b / H111) is 2.0 or more and 150 or less, it is possible to suppress the concentration of stress on the inner peripheral edge. The thickness H111 of the central portion 111 between the separator 20 and the fuel cell main body 10 is the distance in the stacking direction between the separator 20 and the fuel cell main body 10 in the central portion 111. The thickness H111 of this embodiment is smaller than the thickness of the central portion 111. The ratio (L112b / H111) is specified by the thickness H111 and the maximum protrusion length L112b measured from the cross section in the stacking direction shown in FIG. 4 in one stretched portion having a curved portion.

Further, the second protruding portion 113 is in contact with the fuel cell main body 10. Specifically, the second protrusion 113 is in contact with the side surface of the fuel electrode 13. The ratio (H113 / H111) of the thickness H113 of the second protruding portion 113 of the portion in contact with the side surface of the fuel cell body 10 with respect to the thickness H111 of the central portion 111 between the separator 30 and the fuel cell body 10. It is 0.02 or more and 5 or less. When the ratio (H113 / H111) is 0.02 or more and 5 or less, the stress can be dispersed to the fuel cell main body 10 as well, so that the local concentration of stress can be suppressed. The thickness H113 of this embodiment is smaller than the thickness of the fuel electrode 13. The ratio (H113 / H111) is specified by the thicknesses H111 and H113 measured from the cross section in the stacking direction shown in FIG. 4 in one stretched portion having a curved portion.

Further, as shown in FIG. 4, the ratio (E113 / H111) of the exposed length E113 of the second protruding portion 113 to the thickness H111 of the central portion 111 between the separator 30 and the fuel cell main body 10 is 1. It exceeds and is 10 or less. When the ratio (E113 / H111) is more than 1 and 10 or less, the stress applied to the outer peripheral edge 116 can be dispersed. The exposed length E113 of the second protruding portion 113 is the length of the portion indicated by the arrow shown in FIG. 4, and is the maximum length from the contact point with the fuel cell main body 10 to the contact point with the separator 30 in the second protruding portion 113. The length. The ratio (E113 / H111) is specified by the thickness H111 and the exposure length E113 measured from the cross section in the stacking direction shown in FIG. 4 in one stretched portion having a curved portion.

The ratio (L112b / L112a), ratio (L113b / L113a), ratio (L112b / L111), ratio (L113b / L111), ratio (L112b / H111), ratio (H113 / H111), and ratio (E113 / H111) described above. ) Is, for example, a method of masking the fuel cell body 10 and applying the material to be the first bonding material 110 in the step of applying the material to be the first bonding material 110 to the fuel cell body 10 and the separator 30. It can be controlled by a method of precisely controlling the coating amount of the material to be the first bonding material 110 after controlling the space between the fuel cell body 10 and the separator 30.

The first protruding portion 112 and the second protruding portion 113 have exposed surfaces exposed to gas. Specifically, the exposed surfaces of the first protruding portion 112 and the second protruding portion 113 are exposed to a gas such as an oxidant gas or a fuel gas. On the other hand, the central portion 111 between the separator 30 and the fuel cell main body 10 does not have an exposed surface exposed to gas. Specifically, in the stacking direction, the central portion 111 between the lower surface of the separator 30 and the upper surface of the fuel cell body 10 does not have an exposed surface exposed to gas.

The porosity of the first protruding portion 112 and the porosity of the central portion 111 are different. Specifically, the porosity of the first protrusion 112 is greater than the porosity of the central portion 111 between the separator 30 and the fuel cell body 10. In this case, since the deformability of the first protruding portion 112 to which a stress larger than that of the central portion 111 is applied can be improved, the stress can be relaxed. The ratio of the porosity of the first protruding portion 112 to the porosity of the central portion 111 between the separator 30 and the fuel cell main body 10 is, for example, 1.25 or more and 200 or less.

The porosity of the second protruding portion 113 and the porosity of the central portion 111 are different. Specifically, the porosity of the second protrusion 113 is greater than the porosity of the central portion 111 between the separator 30 and the fuel cell body 10. In this case, the deformability of the second protruding portion 113 to which a stress larger than that of the central portion 111 is applied between the separator 30 and the fuel cell main body 10 can be improved, so that the stress can be relaxed. The ratio of the porosity of the second protruding portion 113 to the porosity of the central portion 111 between the separator 30 and the fuel cell main body 10 is, for example, 1.25 or more and 200 or less.

The porosity of the central portion 111 between the separator 30 and the fuel cell main body 10 and the porosity of the central portion 111 on the separator 30 may be the same or different. The central portion 111 on the separator 30 of the present embodiment has an exposed surface exposed to gas.

The porosity of the first protruding portion 112 is, for example, 1.0% or more and 25% or less, preferably 5.0% or more and 25% or less. The porosity of the central portion 111 between the separator 30 and the fuel cell main body 10 is, for example, 0.10% or more and 4.0% or less. The porosity of the central portion 111 on the separator 30 is, for example, 1.0 or more and 25% or less. The porosity of the second protruding portion 113 is, for example, 1.0% or more and 25% or less, preferably 5.0% or more and 25% or less.

The above-mentioned "porosity" is a value measured by quantifying the pore portion of the cross-sectional image of the FE-SEM by image analysis. Specifically, an image magnified 1000 to 20000 times by FE-SEM is analyzed by the image analysis software HALCON manufactured by MVTech. The area occupancy of each of the material portion and the pore portion constituting the bonding material member is obtained on the cross-sectional image after the analysis, and the area occupancy of the pore portion is defined as the porosity. The cross-sectional image was taken for each of the 10 visual fields of the central portion 111, the first protruding portion 112, and the second protruding portion 113 to quantify the porosity, and the average value was calculated as the central portion 111, the first protruding portion 112, and the second protruding portion 113. Let it be the porosity of part 113.

Further, the maximum pore diameter of the first protruding portion 112 is larger than the maximum pore diameter of the central portion 111 between the separator 30 and the fuel cell main body 10. The maximum pore diameter of the second protruding portion 113 is larger than the maximum pore diameter of the central portion 111 between the separator 30 and the fuel cell main body 10. The maximum pore diameter of the first protruding portion 112 is, for example, 0.1 μm or more and 20 μm or less, and the maximum pore diameter of the central portion 111 between the separator 30 and the fuel cell body 10 is, for example, 0.05 μm or more and 10 μm or less. The maximum pore diameter of the second protruding portion 113 is, for example, 0.1 μm or more and 20 μm or less.

The above-mentioned "pore diameter" is a value of a circle-equivalent diameter of a pore obtained by image analysis of a cross-sectional image of an FE-SEM. Here, the equivalent circle diameter is the diameter of a circle having an area value of a measurement target (particles or pores) obtained by image analysis of a cross section. Similar to the calculation of porosity, the cross-sectional image is taken for 10 fields of view and the pore diameter is quantified. The average pore diameter of each visual field is calculated, and the average of the average pore diameters of the 10 visual fields is defined as the pore diameter. However, when calculating the average pore diameter, those with a pore diameter of 0.01 μm or less are excluded.

The porosity and pore diameter of the central portion 111, the first protruding portion 112, and the second protruding portion 113 are, for example, the size and amount (volume ratio) of the pore-forming material containing the organic component added before the heat treatment. Can be controlled by adjusting.

The first bonding material 110 is, for example, crystallized glass. As the crystallized glass, for example, SiO _2- B ₂ O ₃ system, SiO _2- CaO system, or SiO _2- Mg O system can be adopted. In the present specification, the crystallized glass has a ratio (crystallinity) of "volume occupied by the crystal phase" to the total volume of 60% or more, and "volume occupied by the amorphous phase and impurities" with respect to the total volume. Refers to glass with a proportion of less than 40%. Amorphous glass, brazing material, ceramics, or the like may be used as the material of the first bonding material 110. Specifically, the first bonding material 110 is at least one selected from the group consisting of SiO _2- MgO-B ₂ O _3- Al ₂ O ₃ system and SiO _2- MgO-Al ₂ O _3- ZnO system. .. The first bonding material 110 may be composed of a single material or may be composed of a plurality of materials. When composed of a plurality of materials, the materials may be in contact and integrated, or may be partially or wholly non-contact.

[Joining separator with first bonding material]
As shown in FIGS. 3 and 4, the inner peripheral edge portion 31 of the separator 30 is joined to the outer peripheral edge portion 14 of the fuel cell main body 10 by the first joining member 110. The main surface of the inner peripheral edge portion 31 of the separator 30 is inclined with respect to a direction (y-axis direction) orthogonal to the stacking direction (z-axis direction). That is, the inner peripheral edge portion 31 is inclined with respect to the fuel cell main body 10. The inner peripheral edge portion 31 is in contact with the surface 114 of the first joining member 110.

The stacking direction is specified by a region joined to the first joining member 110 in the fuel cell main body 10. Specifically, the region joined to the first bonding material 110 in the fuel cell main body 10 in the non-power generation state is determined, and the direction orthogonal to the main surface of the layer constituting the region is specified as the stacking direction. .. The inner peripheral edge portion 31 of the separator 30 in a state where power is not generated is inclined with respect to the direction orthogonal to the stacking direction specified in this way. That is, by observing the inner peripheral edge portion 31 and the outer peripheral edge portion 14 joined to the first joining member 110 in the cell stack device 1 that does not generate electricity, the main surface of the inner peripheral edge portion 31 of the separator 30 is in the stacking direction. Whether or not it is tilted with respect to the orthogonal direction is specified.

The inner peripheral edge portion 31 of the separator 30 and the outer peripheral edge portion 14 of the fuel cell main body 10 face each other via the first joining member 110. The facing surfaces (one of the main surfaces) of the inner peripheral edge portion 31 and the outer peripheral edge portion 14 are non-parallel to each other. Specifically, in the cell stack device 1 in a state where power is not generated, the main surfaces of the inner peripheral edge portion 31 and the outer peripheral edge portion 14 joined to the first joining member 110 are not parallel to each other. In FIG. 4, the facing surface of the outer peripheral edge portion 14 extends in the horizontal direction, and the facing surface of the inner peripheral edge portion 31 extends upward.

The angle θ formed by the extending direction of the main surface of the inner peripheral edge portion 31 and the direction orthogonal to the stacking direction exceeds 0 degrees. The angle θ is, for example, 0.05 degrees or more and 30 degrees or less. This angle θ is a value obtained by the height (height / length) of the inner peripheral edge portion 31 in the z-axis direction with respect to the length of the inner peripheral edge portion 31 in the y-axis direction.

The inner peripheral edge 31 includes an inner peripheral edge 33 that defines the opening. In the stacking direction shown in FIG. 4, the inner peripheral edge 33 of the separator 30 is chamfered. Specifically, at least a part of the inner peripheral edge 33 of the separator 30 is curved in an arc shape. That is, the inner peripheral edge 33 has an R shape. In the present embodiment, the corner portion of the inner peripheral edge 33 on the air pole side is rounded. The corners of the inner peripheral edge 33 on the fuel pole 13 side may be rounded, and both the corners on the air pole 12 side and the fuel pole 13 side may be rounded. By chamfering the inner peripheral edge 33 into an R shape or the like, stress can be relaxed even if the separator 30 is deformed due to a temperature change due to power generation or the like.

[Second joint material]
As shown in FIGS. 2 and 3, the second bonding material 120 is provided on a member constituting the flow path of the oxidant gas supplied to the air electrode 12 and the flow path of the fuel gas supplied to the fuel electrode 13. There is. Specifically, the second joining member 120 joins the separator 30, the interconnector 40, and the fastening members 23, 27. The second bonding material 120 isolates the inside and the outside of the cell stack device 1. That is, as a result of sealing the gaps between the plurality of members, the second joining member 120 divides the internal space and the external space of the cell stack device 1.

The second bonding material 120 has a frame shape. That is, the second bonding material 120 is a continuous integral ring.

The cell stack device 1 may further include a third joining material (not shown). The third joining material is, for example, a joining material that joins the separator 30 and the interconnector 40. Specifically, the third joining material joins the separator 30 and the interconnector 40 alone without using other members or in a state where other members are arranged. Other members include, for example, an insulating material for insulating between the separator 30 and the interconnector 40, a compression sealing material, and the like. When the separator 30 and the interconnector 40 are sealed with other members, the third bonding material may be omitted.

The cell stack device 1 configured as described above generates electricity as follows. An oxidant gas is passed through the air electrode 12, and a fuel gas (hydrogen gas or the like) is passed through the fuel electrode 13. Then, when the cell stack device 1 is connected to an external load, the electrochemical reaction shown in the following formula (1) occurs at the air electrode 12, and the electrochemical reaction shown in the following formula (2) occurs at the fuel pole 13. Flows.
(1/2) ・ O ₂ + 2e ⁻ → O ^2- … (1)
H ₂ + O ^2- → H ₂ O + 2e ⁻ … (2)

For example, the volume of the fuel electrode 13 of the fuel cell body 10 changes due to a thermal cycle such as a temperature change due to this power generation. In the present embodiment, the outer peripheral edge 116 of the first joint member 110 has a curved portion, and the ratio of the maximum protrusion length L113b of the second protrusion 113 to the minimum protrusion length L113a of the second protrusion 113 (L113b / L113a) is 1.01 or more and 10.0 or less. Therefore, the direction of the stress applied to the first bonding material 110 due to the deformation of the fuel electrode 13 is dispersed. As a result, the stress remaining on the outer peripheral edge of the first bonding material 110 is dispersed, and the concentration of stress is easily suppressed. Therefore, the stress in the first bonding material 110 can be relaxed.

Further, in the present embodiment, the main surface of the inner peripheral edge portion 31 of the separator 30 joined by the first joining member 110 is inclined with respect to the direction orthogonal to the stacking direction. Therefore, since the separator 30 is inclined with respect to the fuel cell main body 10, the flexibility of the separator 30 is increased. As a result, when the fuel electrode 13 is deformed by the thermal cycle, the separator 30 is subsequently deformed. By the deformation of the separator 30, the stress applied to the first bonding material 110 can be further relaxed.

[Modification example]
Although the embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made without departing from the spirit of the present invention.

Modification 1
In the above-described embodiment, the structure in which the entire fifth to eighth stretched portions 116a to 116d are curved has been described as an example, but the present invention is not limited thereto. For example, the entire stretched portion may be curved and the remaining stretched portion may be straight. Further, for example, a part of at least one stretched portion may be curved. That is, at least one stretched portion may have a curved portion and a straight portion.

Further, for example, as shown in FIG. 6, at least one stretched portion of the outer peripheral edge 116 may be curved so as to be separated from the separator 30. In FIG. 6, the entire fifth to eighth stretched portions 116a to 116d are curved so as to separate from the separator 30.

Further, for example, as shown in FIG. 7, a part or all of the fifth to eighth stretched portions 116a to 116d may have a wavy shape. The wavy shape is a concave-convex shape in which concave portions and convex portions are alternately repeated.

Modification 2
In the above-described embodiment, at least a part of the inner peripheral edge 115 and the outer peripheral edge 116 is curved, but the inner peripheral edge 115 may be formed by a straight line. Further, the first to fourth stretched portions of the inner peripheral edge 115 may be curved so as to be separated from the fuel cell main body 10 as shown in FIG. 6, and have a wavy shape as shown in FIG. May be good.

Modification 3
In the above-described embodiment, the inner peripheral edge portion 31 is embedded in the first joining member 110, but is not limited thereto. For example, as shown in FIG. 8, the inner peripheral edge portion 31 of the separator 30 may be in contact with the surface 114 of the first joining member 110. In the case of FIG. 8, the central portion 111 is sandwiched between the fuel cell main body 10 and the separator 30. That is, the central portion 111 is not arranged on the upper side in the stacking direction with respect to the separator 30, and is not arranged on the lower side in the stacking direction with respect to the fuel cell main body 10. In this case, the entire central portion 111 does not have an exposed surface exposed to gas. Specifically, the outer surface of the central portion 111 is in contact with the fuel cell body 10 and the separator 30.

Further, for example, as shown in FIG. 9, only a part of the inner peripheral edge portion 31 may be buried. Specifically, a part of the inner peripheral edge portion 31 is in contact with the surface 114 of the first joining member 110, and the other part of the inner peripheral edge portion 31 is embedded in the first joining member 110.

Modification 4
In the above-described embodiment, the outer peripheral side of the inner peripheral edge portion 31 is inclined so as to be separated from the fuel cell main body 10, but the present invention is not limited to this. As shown in FIGS. 10 and 11, the inner peripheral edge portion 31 may be inclined so as to approach the fuel cell main body 10 toward the outer peripheral side.

In this modification, the inner peripheral edge portion 31 extends along the surface 114 of the first joining member 110. In this case, in the separator 30, the bonding area with the first bonding material 110 increases.

The separator 30 in FIG. 10 is curved downward. Specifically, the separator 30 is curved downward as a whole. The separator 30 in FIG. 11 is curved downward and upward. Specifically, in the separator 30, the outer peripheral side of the separator 30 is curved upward from the inner peripheral edge portion 31.

Modification 5
In the above-described embodiment, the first joining material 110 has a shape in which a part of the ellipse is missing in a cross-sectional view, but the first joining material 110 is not limited to this. The first bonding material 110 can have various shapes, and may have, for example, the shapes shown in FIGS. 9 and 11 to 13 in a cross-sectional view.

Modification 6
In the above-described embodiment, the entire separator 30 is curved, but the present invention is not limited to this. A part of the separator 30 may be curved, and may have, for example, a bent portion and a stepped portion. Further, the separator 30 may extend so as to be linearly inclined with respect to the fuel cell main body 10. The separator 30 has a shape in which at least a part of the separator 30 bends.

Modification 7
In the above-described embodiment, the inner peripheral edge 115 of the surface of the first joint material 110 in contact with the fuel cell body 10 is located on the innermost peripheral side of the first joint material 110, but is not limited thereto. For example, in the stacking direction, the first bonding member 110 that does not contact the fuel cell body 10 may be arranged on the inner peripheral side of the inner peripheral edge 115 of the surface that contacts the fuel cell body 10.

Modification 8
In the above-described embodiment, the direction orthogonal to the stacking direction is the y-axis direction, and the inner peripheral edge portion 31 is inclined with respect to the y-axis direction, but the present invention is not limited to this. For example, the direction orthogonal to the stacking direction may be inclined with respect to the y-axis direction, and the inner peripheral edge portion 31 may extend in the y-axis direction. Further, the direction orthogonal to the stacking direction is inclined with respect to the y-axis direction, and the inner peripheral edge portion 31 is also inclined with respect to the y-axis direction, and may intersect with each other. Even in this case, since the separator 30 has flexibility, the separator 30 can absorb the deformation according to the deformation of the fuel cell body 10. The main surface of the inner peripheral edge portion 31 of the present invention may be parallel to the direction orthogonal to the stacking direction.

Modification 9
In the above-described embodiment, the outer peripheral portions of the fuel electrode substrate 131 and the fuel electrode active portion 132 have a stepped structure, but the present invention is not limited to this. For example, the outer peripheral surfaces of the fuel electrode substrate 131 and the fuel electrode active portion 132 may be aligned.

[Example 1]
In this example, the effect of the ratio (L113b / L113a) of the maximum protrusion length 113b of the second protrusion 113 to the minimum protrusion length 113a of the second protrusion 113 was investigated.

(Sample Nos. 1 to 5)
The cell stack device shown in FIGS. 1 to 5 was prepared. The first bonding material is crystallized glass. As shown in FIG. 5, the four stretched portions of the outer peripheral edge 116 of the first joining material 110 had curved portions. The ratio (L113b / L113a) of the maximum protrusion length L113b of the first protrusion 112 to the minimum protrusion length L113a of the second protrusion 113 of each sample is as shown in Table 1 below.

(Sample No. 6)
Sample No. No. 6 did not have a curved portion in the four stretched portions. Specifically, the two sets of stretched portions are parallel to each other, and the ratio of the maximum protruding length L113b of the second protruding portion 113 to the minimum protruding length L113a of the second protruding portion 113 (L113b / L113a) is 1. Met.

(Evaluation methods)
Sample No. The cell stack devices 1 to 6 were examined for the amount of gas leak and the presence or absence of cracks by a thermal cycle test. Specifically, each cell stack device is installed in an electric furnace, and after repeating raising and lowering from room temperature to 800 ° C. at an elevating temperature rate of 400 ° C./hr 10 times, it is taken out from the electric furnace to generate gas leaks and cracks. I checked for the presence or absence of.

Regarding the amount of gas leak, the flow rate of gas leaking from the air electrode to the fuel electrode was measured. Specifically, after sealing the oxidant gas discharge pipe outlet end and the fuel gas discharge pipe inlet end of the cell stack device 1, argon gas is supplied from the oxidant gas supply pipe, and the oxidant gas supply side The amount of gas leak was measured with a flow meter provided at the outlet end of the fuel gas supply pipe under the condition that the pressure was pressurized by 10 kPa. The presence or absence of cracks was confirmed by disassembling the cell stack device, applying a penetrant flaw detector to the surface of the first bonding material, and observing with a microscope. These results are listed in "Evaluation Results" in Table 1 below.

The "evaluation results" in Table 1 were evaluated in four stages according to the amount of cracks and gas leaks. "◎" means that there were no cracks and no gas leak, "○" means that minute cracks were generated and there was no gas leak, and "△" means that minute cracks were generated. Moreover, it means that the amount of gas leak was small (less than 1 cc / min), and "x" means that a large crack occurred and the amount of gas leak was large (1 cc / min or more).

(Evaluation results)
As shown in Table 1, the sample No. 1 in which the stretched portion of the outer peripheral edge of the first bonding material did not have a curved portion. In No. 6, the stress of the first joint material could not be sufficiently relaxed, so that cracks occurred. As a result, a large amount of argon gas introduced into the internal space leaked out.

On the other hand, the sample No. 1 in which the stretched portion of the outer peripheral edge of the first bonding material had a curved portion. In Nos. 1 to 5, the stress remaining on the inner peripheral edge of the first bonding material was dispersed, so that the stress could be relaxed. Therefore, cracks generated in the first bonding material could be suppressed. As a result, it was confirmed that the gas leak could be suppressed. In particular, the sample No. in which the ratio (L113b / L113a) of the maximum protruding length 113b of the second protruding portion 113 to the minimum protruding length 113a of the second protruding portion 113 was 1.01 or more and 10.0 or less. In Nos. 1 to 4, no through cracks occurred, so no gas leak occurred. The sample No. having a ratio (L113b / L113a) of 1.10 or more and 8.00 or less. In 2 and 3, the occurrence of cracks could be suppressed very much.

[Example 2]
In this example, the effect of the ratio (L113b / L111) of the maximum protrusion length L113b of the second protrusion 113 to the width L111 of the central portion 111 was investigated.

(Sample No. 7-10)
Sample No. In the cell stack device 7 to 10, the ratio (L113b / L113a) of the maximum protrusion length L113b of the second protrusion 113 to the minimum protrusion length L113a of the second protrusion 113 is 1.01 or more and 10.0 or less. Yes, as shown in Table 2 below, the maximum protrusion length L113b of the second protrusion 113 and the width L111 of the central portion 111 were changed.

(Evaluation methods)
Sample No. For the cell stack devices of 7 to 10, the heat cycle test of Example 1 described above was made severe, and the amount of gas leak and the presence or absence of cracks were examined. Specifically, each cell stack device is installed in an electric furnace, and after repeating raising and lowering from room temperature to 800 ° C. at an elevating temperature rate of 600 ° C./hr 20 times, it is taken out from the electric furnace to generate a gas leak amount and cracks. I checked for the presence or absence of. The results are shown in Table 2 below. The evaluation criteria are the same as in Example 1.

(Evaluation results)
As shown in Table 2, the ratio (L113b / L111) of the maximum protruding length L113b of the second protruding portion 113 to the width L111 of the central portion 111 is 0.1 or more and 3 or less. 8 and 9 are sample Nos. It was found that the occurrence of cracks could be suppressed even in a harsh thermal cycle test as compared with 7 and 10.

[Example 3]
In this embodiment, the ratio of the thickness H113 of the second protruding portion 113 of the portion in contact with the side surface of the fuel cell body 10 to the thickness H111 of the central portion 111 between the separator 30 and the fuel cell body 10 (H113). The effect of / H111) was investigated.

(Sample Nos. 11 to 15)
Sample No. In the cell stack devices 11 to 15, the ratio (L113b / L113a) of the maximum protruding length L113b of the second protruding portion 113 to the minimum protruding length L113a of the second protruding portion 113 is 1.01 or more and 10.0 or less. Yes, as shown in Table 3 below, the thickness H111 of the central portion 111 between the separator 30 and the fuel cell main body 10 and the second protruding portion 113 of the portion in contact with the side surface of the fuel cell main body 10. The thickness H113 was changed. In addition, sample No. The second protruding portion 113 of the first bonding material of 11 did not come into contact with the side surface of the fuel cell main body 10.

(Evaluation methods)
Sample No. The cell stack devices of 11 to 15 were examined for the amount of gas leak and the presence or absence of cracks by the thermal cycle test of Example 2 which was more severe than that of Example 1.

(Evaluation results)
As shown in Table 3, the sample No. 1 in which the second protruding portion 113 is in contact with the fuel cell main body 10. In Nos. 12 to 15, the second protruding portion 113 was not in contact with the fuel cell main body 10. Compared with No. 11, cracks could be suppressed even in a harsh heat cycle test. Further, the ratio of the thickness H113 of the second protruding portion 113 of the portion in contact with the side surface of the fuel cell body 10 to the thickness H111 of the central portion 111 between the separator 30 and the fuel cell body 10 (H113 / H111). Sample No. of 0.02 or more and 5 or less. 13 and 14 are sample Nos. It was found that the occurrence of cracks could be further suppressed as compared with 12 and 15.

[Example 4]
In this example, the effect of the porosity of the second protruding portion and the porosity of the central portion between the separator 30 and the fuel cell body 10 was investigated.

(Sample Nos. 16-18)
Sample No. In the cell stack devices 16 to 18, the ratio (L113b / L113a) of the maximum protrusion length L113b of the second protrusion 113 to the minimum protrusion length L113a of the second protrusion 113 is 1.01 or more and 10.0 or less. Yes, as shown in Table 4 below, the porosities of the central portion 111 and the second protruding portion 113 between the separator 30 and the fuel cell main body 10 were changed.

(Evaluation methods)
Sample No. The cell stack devices 16 to 18 were examined for the amount of gas leak and the presence or absence of cracks by the thermal cycle test of Example 2 which was more severe than that of Example 1.

(Evaluation results)
As shown in Table 4, the sample No. in which the porosity of the second protruding portion 113 between the separator 30 and the fuel cell main body 10 is larger than the porosity (or the maximum pore diameter) of the central portion 111. In sample No. 17, the porosity of the first protruding portion 112 is the same as the porosity of the central portion 111 between the separator 30 and the fuel cell main body 10. In sample No. 16, the porosity of the central portion 111 between the separator 30 and the fuel cell body 10 is larger than the porosity of the second protruding portion 113. It was found that the occurrence of cracks could be further suppressed as compared with 18.

[Example 5]
In this embodiment, the effect of the ratio of the exposed length E113 of the second protruding portion 113 to the thickness H111 of the central portion 111 between the separator 30 and the fuel cell main body 10 (E113 / H111) was investigated.

(Sample Nos. 19 to 22)
Sample No. In the cell stack devices 19 to 22, the ratio (L113b / L113a) of the maximum protrusion length L113b of the second protrusion 113 to the minimum protrusion length L113a of the second protrusion 113 is 1.01 or more and 10.0 or less. Yes, as shown in Table 5 below, the ratio of the thickness H111 of the central portion 111 and the exposed length E113 of the second protruding portion 113 between the separator 30 and the fuel cell body 10 (E113 / H111). Changed.

(Evaluation methods)
Sample No. The cell stack devices 19 to 22 were examined for the amount of gas leak and the presence or absence of cracks by the thermal cycle test of Example 2 which was more severe than that of Example 1.

(Evaluation results)
As shown in Table 5, the ratio (E113 / H111) of the exposed length E113 of the second protruding portion 113 to the thickness H111 of the central portion 111 between the separator 30 and the fuel cell main body 10 exceeds 1. Sample No. 10 or less. 20 and No. Reference numeral 21 is sample No. 21. It was found that the occurrence of cracks could be suppressed even in a harsher thermal cycle test as compared with 19 and 22.

1 Cell stack device 10 Fuel cell cell 30 Separator 31 Inner peripheral edge 110 Joint material 111 Central part 112 First protruding part 113 Second protruding part 115 Inner peripheral edge 116 Outer peripheral edge 116a, 116b, 116c, 116d Extension 116e, 116f, 116g, 116h connecting part

Claims (5)

A solid electrolyte, and a flat fuel cell body having a fuel electrode and an air electrode laminated so as to sandwich the solid electrolyte.
A frame-shaped separator having an opening that exposes an area other than the outer peripheral edge of the fuel cell body, and a separator having an inner peripheral edge that overlaps the outer peripheral edge of the fuel cell body.
A bonding material for joining the outer peripheral edge of the fuel cell body and the inner peripheral edge of the separator.
With
In the stacking direction view, the outer peripheral edge of the joining material has two sets of stretched portions facing each other and a connecting portion for connecting the stretched portions.
At least one stretched portion has a curved portion and has a curved portion.
The joining material is
In the stacking direction, the fuel cell body and the central portion overlapping the separator,
A first protruding portion that protrudes from the central portion toward the inner peripheral side,
A second protruding portion that protrudes from the central portion toward the outer peripheral side,
Have,
The ratio of the maximum protrusion length of the second protrusion to the minimum protrusion length of the second protrusion is 1.01 or more and 10.0 or less.
Fuel cell.
The ratio of the maximum protrusion length of the second protrusion to the width of the center is 0.1 or more and 3 or less.
The fuel cell according to claim 1.
The second protruding portion is in contact with the side surface of the fuel cell main body.
The ratio of the thickness of the second protruding portion of the portion in contact with the side surface of the fuel cell body to the thickness of the central portion between the separator and the fuel cell body is 0.02 or more and 5 or less. is there,
The fuel cell according to claim 1 or 2.
The porosity of the second protrusion is larger than the porosity of the central portion between the separator and the fuel cell body.
The fuel cell according to any one of claims 1 to 3.
The ratio of the exposed length of the second protrusion to the thickness of the central portion between the separator and the fuel cell main body is more than 1 and 10 or less.
The fuel cell according to any one of claims 1 to 4.

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