Solid oxide fuel cell, and method for manufacturing solid oxide fuel cell

Abstract

To provide a solid oxide fuel cell capable of satisfying strength, sealing performance and insulation of a junction between dissimilar materials of a power generation cell and a metal thin plate at the same time.SOLUTION: A solid oxide fuel cell includes: a power generation cell including a fuel electrode layer, an electrolyte layer and an air electrode layer stacked in this order; a support layer disposed to sandwich the fuel electrode layer together with the electrolyte layer; and a separator disposed to sandwich the support layer together with the power generation cell. The separator includes a connection part disposed to circle around the outside of an outline of the power generation cell in plan view. The air electrode layer is disposed in a central part on the other main surface of the electrolyte layer. A bonding auxiliary layer that is a mixture of a metal material and ceramic and has an air tight structure is disposed to circle around a peripheral part of the other main surface of the electrolyte layer, and is placed away from the air electrode layer. A seal portion formed of a material containing the metal material is disposed in the connection part so as to circle around an outer periphery of the power generation cell and the support layer. The seal portion is bonded at least to a side face of the bonding auxiliary layer and the connection part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a solid oxide fuel cell and a method for manufacturing the same.

Background Art

[0002] Patent Document 1 discloses a technique for housing a power generation cell of a solid oxide fuel cell in a metal frame, disposing a sealing material between the side surface of the power generation cell and the inner wall of the metal frame, and joining the power generation cell and the metal frame.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in joining dissimilar materials between a power generation cell made of ceramics and a metal frame, it is difficult to simultaneously satisfy the strength, sealing performance, and insulation of the joint.

[0005] An object of the present invention is to provide a solid oxide fuel cell and a method for manufacturing the same that simultaneously satisfy the strength, sealing performance, and insulation of a joint between dissimilar materials made of a power generation cell and a metal thin plate.

Means for Solving the Problems

[0006] According to the solid oxide fuel cell of the present invention, a power generation cell including an electrolyte layer, a first electrode layer disposed on one main surface of the electrolyte layer, and a second electrode layer disposed on the other main surface of the electrolyte layer; a support layer disposed so as to sandwich the first electrode layer together with the electrolyte layer and supporting the power generation cell; and a metal thin plate disposed so as to sandwich the support layer together with the power generation cell. In this solid oxide fuel cell, the metal thin plate includes a connection portion disposed so as to go around the outside of the outer shapes of the electrolyte layer, the first electrode layer, and the second electrode layer in a plan view, and the second electrode layer is disposed at the center of the other main surface of the electrolyte layer. Further, a joining auxiliary layer having an airtight structure and being a mixture of a metal material and a ceramic goes around the peripheral portion of the other main surface of the electrolyte layer and is disposed so as to be separated from the second electrode layer, and a seal portion formed of a material containing a metal material is disposed in the connection portion so as to go around the outer periphery of the power generation cell and the support layer. And the seal portion is joined to at least the side surface of the joining auxiliary layer and the connection portion.

Advantages of the Invention

[0007] According to the present invention, since the joining auxiliary layer has an airtight structure, the joining strength with the seal portion is ensured. Further, since the seal portion contains a metal, the joining strength with the metal thin plate is also ensured. And since the seal portion is joined so as to connect the metal thin plate and the joining auxiliary layer, it is possible to suppress a decrease in the sealing performance while sealing the side surfaces of the power generation cell and the support layer. Also, since the joining auxiliary layer is separated from the second electrode layer, it is possible to ensure the insulation between the first electrode layer and the second electrode layer. From the above, it is possible to simultaneously satisfy the strength, the sealing performance, and the insulation of the joint portion between different materials by the power generation cell and the metal thin plate.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] [First embodiment] Fig. 1 is a cross-sectional view of a solid oxide fuel cell 100 of a first embodiment, Fig. 1(a) showing a basic form, Fig. 1(b) showing a first modified example of a sealing portion 5, and Fig. 1(c) showing a second modified example of a sealing portion 5. Fig. 2 is a plan view of the solid oxide fuel cell 100 (basic form) of the first embodiment.

[0011] As shown in FIG. 1(a), the solid oxide fuel cell 100 of the first embodiment is formed by laminating a fuel electrode layer 12, an electrolyte layer 11, and an air electrode layer 13 in this order on one main surface of a support layer 2, and the fuel electrode layer 12, the electrolyte layer 11, and the air electrode layer 13 form a power generation cell 1.

[0012] The air electrode layer 13 is (La,Sr)MnO 3 (LSM), (La,Sr)CoO 3 (LSC), (La,Sr)(Co,Fe)O 3 The cathode layer 13 is made of a material such as LSCF and is an electrode to which a cathode gas (air) is supplied from the outside. The air cathode layer 13 receives electrons (e - ) is supplied, oxygen molecules (O 2 ) in the air electrode layer 13 (1 / 2O 2 +2e - →O 2- ) to form oxygen ions (O 2- )

[0013] The electrolyte layer 11 is made of zirconium oxide (ZrO 2 ), cerium oxide (CeO 2)It is made of a ceramic material having oxygen ion conductivity, such as yttria-stabilized zirconia (YSZ) added with rare earth elements (yttrium (Y), gadolinium (Gd), scandium (Sc), etc.), gadolinium-doped ceria (GDC), etc., and hermetically separates the gases supplied to the air electrode layer 13 and the fuel electrode layer 12 respectively. The electrolyte layer 11 supplies the oxygen ions (O 2- ) generated in the air electrode layer 13 to the fuel electrode layer 12.

[0014] The fuel electrode layer 12 is formed with a porous structure having a catalytic function in the skeleton, such as Ni-YSZ, etc. In addition, it is composed of a single ceramic material having oxygen ion conductivity or a porous skeleton surface of a mixture with a metal material, on which catalytic particles such as Ni are later supported. It is an electrode to which anode gas is supplied from the outside. The fuel electrode layer 12 reacts the oxygen ions (O 2- ) supplied from the air electrode layer 13 through the electrolyte layer 11 with the fuel in the anode gas to form a product and release electrons (e - ). In particular, when hydrogen (H 2 ) is used as the fuel, the reaction (H 2 +O 2- →H 2 O+2e - ) in the fuel electrode layer 12 generates water (H 2 O) and supplies electrons (e - ) to the external circuit.

[0015] The support layer 2 is formed of a material having electron conductivity and is made of a metal or an alloy. For example, it is formed of a metal material containing iron (Fe) and chromium (Cr), and supports the power generation cell 1 to ensure the strength of the whole cell.

[0016] On the other main surface of the support layer 2, a separator 3 (thin metal plate) is attached. The separator 3 is formed of a metal material (e.g., stainless steel (SUS)) containing, for example, aluminum (Al). The separator 3 has a corrugated portion 32 that forms a first flow path 61 through which anode gas flows between the separator 3 and the support layer 2, a flat plate portion 33 that is in surface contact with the support layer 2, and a connection portion 31 that is disposed outside the power generation cell 1 in a plan view (see FIG. 2). The corrugated portion 32 is joined to the support layer 2 at the portion in contact with the support layer 2 by welding or the like.

[0017] Between the corrugated portion 32 and the support layer 2 is a first flow path 61 through which anode gas (fuel) flows. The support layer 2 has a porous structure and allows the anode gas to permeate. Thus, the first flow path 61 communicates with the fuel electrode layer 12, and the anode gas supplied to the first flow path 61 permeates through the support layer 2 and is supplied to the fuel electrode layer 12.

[0018] As will be described later (see FIG. 4), when a plurality of integrated bodies composed of the power generation cell 1, the support layer 2, and the separator 3 are stacked to form a stack structure, the separator 3 communicates with the air electrode layer 13 and forms a second flow path 62 through which cathode gas flows, and the second flow path 62 is spatially separated from the first flow path 61.

[0019] In this embodiment, the arrangement of the fuel electrode layer 12 and the air electrode layer 13 may be interchanged. In this case, the air electrode layer 13 is disposed so as to cover the entire surface of the support layer 2 between the support layer 2 and the separator 3, and the fuel electrode layer 12 is disposed at the central portion of the electrolyte layer 11 in a plan view. Then, cathode gas is supplied to the first flow path 61, and anode gas is supplied to the second flow path 62.

[0020] As shown in FIG. 2, the air electrode layer 13 is disposed at the central portion of the electrolyte layer 11 in a plan view. Correspondingly, the corrugated portion 32 is disposed at a position overlapping the air electrode layer 13 in a plan view. Thus, in the power generation cell 1, a power generation reaction mainly occurs at the portion overlapping the air electrode layer 13 in a plan view.

[0021] As shown in FIGS. 1 and 2, a joining auxiliary layer 4 is disposed on the main surface of the electrolyte layer 11 where the air electrode layer 13 is disposed so as to go around the peripheral portion of the main surface.

[0022] The joining auxiliary layer 4 is a mixture of ceramics and metal, is formed in a frame shape in plan view, and is spatially separated from the air electrode layer 13. The joining auxiliary layer 4 has an airtight structure in which ceramics and metal are mixed.

[0023] The joining auxiliary layer 4 has a first layer 41 disposed on the electrolyte layer 11 and a second layer 42 disposed on the first layer 41.

[0024] In the first layer 41, the blending ratio of ceramics in the mixture of ceramics and metal is set higher than that of the metal (for example, metal: ceramics = 2:8). In the second layer 42, the blending ratio of metal in the mixture of ceramics and metal is set higher than that of the ceramics (for example, metal: ceramics = 8:2).

[0025] As the ceramics to be applied to the joining auxiliary layer 4, the same kind of material as the ceramics used in the electrolyte layer 11, such as zirconium oxide (ZrO 2 ) etc., is suitable. Thereby, the joining strength between the joining auxiliary layer 4 (first layer 41) and the electrolyte layer 11 is ensured. Also, as the metal to be applied to the joining auxiliary layer 4, a metal material (for example, stainless steel) containing the same kind of metal (for example, aluminum) as the seal portion 5 described later is suitable. Thereby, the joining strength between the joining auxiliary layer 4 (second layer 42) and the seal portion 5 described later is ensured.

[0026] In the present embodiment, the joining auxiliary layer 4 has a two-layer structure of the first layer 41 and the second layer 42, but it may have a multi-layer structure of three or more layers, with the blending ratio of metal increasing as going to the upper layer and the blending ratio of ceramics increasing as going to the lower layer. The blending ratio of metal and ceramics (metal: ceramics) may be changed, for example, in the range from 1:9 (the lowermost layer joined to the electrolyte layer 11) to 9:1 (the uppermost layer joined to the seal portion 5).

[0027] As shown in Fig. 2, the seal part 5 is arranged on the connection part 31 so as to go around the side surface of the power generation cell 1. The seal part 5 is joined to the connection part 31, the side surface of the power generation cell 1, and the side surface of the joining auxiliary layer 4. Thereby, a closed space is formed by the electrolyte layer 11, the seal part 5, and the separator 3. The closed space includes the first flow path 61 but does not communicate with the air electrode layer 13 side. Therefore, the anode gas supplied to the first flow path 61 does not leak to the air electrode layer 13 side. Further, for the seal part 5, a metal material (stainless steel) containing the same kind of metal (for example, aluminum) as the separator 3 is applied. Thereby, the joining strength between the seal part 5 and the separator 3 (connection part 31) is ensured.

[0028] The seal part 5 is joined to the separator 3 (connection part 31), the support layer 2, the fuel electrode layer 12, the electrolyte layer 11, and the joining auxiliary layer 4. In particular, the seal part 5 is joined to the separator 3 (connection part 31) with ensured joining strength and the joining auxiliary layer 4. Thereby, the joint part 51 between the seal part 5 and the separator 3 (connection part 31), and the joint part 52 between the seal part 5 and the joining auxiliary layer 4 sandwich the joint part 53 between the seal part 5 and the support layer 2, the joint part 54 between the seal part 5 and the fuel electrode layer 12, and the joint part 55 between the seal part 5 and the electrolyte layer 11 from the thickness direction of the power generation cell 1. Thereby, the thermal strain applied to the joint part 53, the joint part 54, and the joint part 55 and the pressing force during stacking can be reduced. Further, even if the seal performance of the joint part 53, the joint part 54, and the joint part 54 deteriorates, the seal performance of the joint part 51 between the seal part 5 and the separator 3 (connection part 31) and the joint part 52 between the seal part 5 and the joining auxiliary layer 4 is maintained, so that a decrease in the seal performance of the entire seal part 5 can be suppressed.

[0029] By the way, when the seal part 5 and the separator 3 are formed of stainless steel (SUS), chromium oxide (Cr 2 O 3The layer 502 of 2 O 3 ) is formed (see the enlarged view of Fig. 1(a)). However, when the chromium component detaches from the chromium oxide layer 502 and adheres to the air electrode layer 13, the chromium component may damage the catalyst of the air electrode layer 13 and reduce the power generation efficiency of the fuel cell 1. Therefore, by adding aluminum (Al) to stainless steel at a predetermined concentration (2 to 6 wt%), as shown in the enlarged view of Fig. 1(a), a layer 502 of chromium oxide (Cr 2 O 3 ) is formed on the stainless steel 501, and further, a layer 503 of aluminum oxide (Al

[0030] As the form of the seal portion 5, in addition to the basic form of Fig. 1(a), there are a first modified example shown in Fig. 1(b) and a second modified example shown in Fig. 1(c).

[0031] The seal portion 5 of the first modified example is arranged to cover the upper surface of the joining auxiliary layer 4. As a result, as an effect other than the effect of the seal portion 5 shown in Fig. 1(a), the joint portion 51 between the seal portion 5 and the separator 3 (connection portion 31) and the joint portion 56 between the seal portion 5 and the upper surface of the joining auxiliary layer 4 are pressed from the thickness direction of the fuel cell 1, and since they are pressed in the direction of increasing the joint strength, a decrease in the sealing performance of the seal portion 5 can be suppressed.

[0032] The seal portion 5 of the second modified example covers the upper surface of the joining auxiliary layer 4 and enters inside the joining auxiliary layer 4 in a plan view, and is joined to the inner side surface of the joining auxiliary layer 4 and the main surface of the electrolyte layer 11. However, the seal portion 5 is spatially separated from the air electrode layer 13.

[0033] In this case, the bonding strength between the seal portion 5 and the separator 3 (connection portion 31) is ensured as described above. And, for example, when a force is applied to bend the fuel electrode layer 12 side concave and the air electrode layer 13 side convex with respect to the entire fuel cell 1, a force to peel the joint portion 57 from the joint auxiliary layer 4 is not applied to the joint portion 57 with the inner side surface of the joint auxiliary layer 4 of the seal portion 5. Further, since the portion inside the joint auxiliary layer 4 in the plan view of the seal portion 5 is in contact (bonded) with the electrolyte layer 11, a shearing force is not applied to the joint portion 57 even when the bending force is applied. Therefore, by maintaining the sealing performance of the joint portion 51 between the seal portion 5 and the separator 3 and the joint portion 57 between the seal portion 5 and the inner side surface of the joint auxiliary layer 4, a decrease in the sealing performance of the entire seal portion 5 can be suppressed.

[0034] Also, for example, when a force is applied to bend the fuel electrode layer 12 side concave and the air electrode layer 13 side convex with respect to the entire fuel cell 1, a force in the direction of peeling the joint portion 52 from the joint auxiliary layer 4 is not applied to the joint portion 52 with the outer side surface of the joint auxiliary layer 4 of the seal portion 5. Further, since the joint portion 52 is supported by the joint portion 56 with the upper surface of the joint auxiliary layer 4 of the seal portion 5, a shearing force in the direction of shearing the joint portion 52 toward the separator 3 side is not applied even when the bending force is applied. Therefore, the seal portion 5 can suppress a decrease in sealing performance between the joint portion 51 between the seal portion 5 and the separator 3 (connection portion 31) and the joint portion 52 between the seal portion 5 and the outer side surface of the joint auxiliary layer 4.

[0035] As described above, even when a bending force is applied to the fuel cell 1 in the thickness direction, at least the sealing performance (a state where gases do not flow into each other) between the space (first flow path 61) on the fuel electrode layer 12 side and the space (second flow path 62) on the air electrode layer 13 side can be maintained.

[0036] [Manufacturing Process of the First Embodiment] FIG. 3 is a cross-sectional view showing the manufacturing process of the solid oxide fuel cell 100 (second modification) of the first embodiment.

[0037] As a manufacturing process of the solid oxide fuel cell 100 of the present embodiment, first, an integrated body composed of a support layer 2, a fuel electrode layer 12, an electrolyte layer 11, an air electrode layer 13, and a joining auxiliary layer 4 is formed. Specifically, a green sheet (including a pore former) composed of the raw material of the support layer 2 is formed into the shape of the support layer 2, and a green sheet composed of the raw material of the fuel electrode layer 12 and a green sheet composed of the material of the electrolyte layer 11 are laminated thereon. Further, a green sheet (not including a pore former) composed of the material of the joining auxiliary layer 4 (the first layer 41 and the second layer 42) is disposed at the peripheral edge of the green sheet composed of the material of the electrolyte layer 11. Then, by firing the laminate of the green sheets, an integrated structure including the support layer 2, the fuel electrode layer 12, the electrolyte layer 11, and the joining auxiliary layer 4 is formed. This manufacturing method is generally called co-firing, but not limited to this method. A green sheet in which the support layer 2 and the fuel electrode layer 12 are laminated is degreased and fired to obtain a sintered body, and the electrolyte layer 11 is densely formed on the fuel electrode layer 12 by physical vapor deposition (PVD). Further, a green sheet (not including a pore former) composed of the material of the joining auxiliary layer 4 (the first layer 41 and the second layer 42) is disposed at the peripheral edge of the electrolyte layer 11 formed by physical vapor deposition, and an integrated structure can also be formed by following the procedure of firing again. When a material having catalytic activity such as Ni is not contained in the fuel electrode layer 12 during the production of the green sheet, an aqueous solution containing a catalyst material is dropped onto the fuel electrode layer 12, and heat treatment is performed to impart an electrode function to the fuel electrode layer 12. The paste material serving as the material of the air electrode layer 13 is laminated on the electrolyte layer 11 of the integrated structure (the fired product of the support layer 2, the fuel electrode layer 12, the electrolyte layer 11, and the joining auxiliary layer 4). At this time, the paste material serving as the material of the air electrode layer 13 is disposed at the central portion of the electrolyte layer 11 in plan view. By sintering this, the air electrode layer 13 is formed, and an integrated body composed of the support layer 2, the fuel electrode layer 12, the electrolyte layer 11, the air electrode layer 13, and the joining auxiliary layer 4 is formed.

[0038] Next, a metal flat plate serving as the material of the separator 3 is deformed to form a corrugated shape portion 32, and the portion where the corrugated shape portion 32 contacts the support layer 2 and the flat plate portion 33 are joined to the support layer 2 by welding or the like.

[0039] The seal portion 5 is formed by applying, for example, the LMD (Laser Metal Deposition) method. Specifically, the powder metal used as the raw material for the seal portion 5 is arranged following the cross-sectional shape of the seal portion 5, and the powder metal and the separator 3 (connection portion 31) are melted by laser light to form a metal thin film on the separator 3 (connection portion 31). Then, the metal powder material is arranged again on the metal thin film, and the powder metal and the metal thin film are melted by laser light to laminate a new metal thin film on the previously formed metal thin film. By repeating this process, the seal portion 5 is formed.

[0040] As shown in FIG. 3(a), a metal thin film is laminated following the outer shape of the portion joined to the separator 3 (connection portion 31) of the seal portion 5. At this time, a new metal thin film is laminated by melting the metal powder, the metal thin film in contact therewith, and the side surface (metal component) of the power generation cell 1.

[0041] As shown in FIG. 3(b), when the height of the metal thin film reaches the height of the upper surface of the electrolyte layer 11, a metal thin film is laminated following the outer shape of the portion joined to the separator 3 (connection portion 31) of the seal portion 5 and the outer shape of the portion joined to the electrolyte layer 11 of the seal portion 5.

[0042] Then, when the height of the metal thin film reaches the height of the upper surface of the joining auxiliary layer 4, a metal thin film is laminated following the planar shape of the seal portion 5 and laminated to a desired height, thereby forming the seal portion 5 shown in FIG. 1(c).

[0043] By the above manufacturing process, since the seal portion 5 and the separator 3 (connection portion 31) are fusion-connected by metals, the joining strength (i.e., the sealing performance) of the joining portion 51 between the seal portion 5 and the separator 3 is ensured. Also, the joining portion 52 between the outer side surface of the joining auxiliary layer 4 of the seal portion 5, the joining portion 56 between the upper surface of the joining auxiliary layer 4 of the seal portion 5, and the joining portion 57 between the inner side surface of the joining auxiliary layer 4 of the seal portion 5 are also substantially fusion-connected by metals, so the joining strength (i.e., the sealing performance) of the joining portion 52, the joining portion 56, and the joining portion 57 is ensured.

[0044] In addition, since the seal portion 5 is formed after forming an integrated body composed of the power generation cell 1, the support layer 2, and the separator 3, even if there are shape variations in the power generation cell 1, the seal portion 5 can be formed in a manner that cancels out such variations, thereby enhancing the manufacturing yield of the solid oxide fuel cell 100.

[0045] Note that Patent Document 1 discloses a technique in a solid oxide fuel cell in which a power generation cell is housed in a metal frame (separator), and a sealing material (made from a metal paste as a raw material) is injected between the side surface of the power generation cell and the inner wall of the metal frame to join the power generation cell and the metal frame.

[0046] However, when the metal paste is fired to form a sealing material, firing shrinkage occurs in the sealing material, so peeling may occur at the interface between the sealing material and the power generation cell or at the interface between the sealing material and the metal frame, and there is a possibility of cross leakage occurring between the anode and the cathode through the seal portion 5.

[0047] In addition, in Patent Document 1, the thermal strain received from the power generation cell and the metal frame and the load when in a stack structure may cause the behavior of peeling the sealing material.

[0048] However, by adopting the configuration of the first modification example (Fig. 1(b)), when the solid oxide fuel cell 100 is formed into a stack structure and pressed from the thickness direction, or when power generation is executed and the temperature of the solid oxide fuel cell 100 rises and the seal portion 5 etc. expand, the joint portion 51 of the seal portion 5 with the separator 3 (connection portion 31) is pressed against the separator 3 (connection portion 31), and the joint portion 56 of the seal portion 5 with the joint auxiliary layer 4 is pressed against the joint auxiliary layer 4. Therefore, the joint portion 51 and the joint portion 56 are not peeled off, and a decrease in the sealing performance of the seal portion 5 can be suppressed.

[0049] Moreover, by adopting the configuration of the second modification (Fig. 1(c)), when the solid oxide fuel cell 100 is formed into a stack structure and pressed from the thickness direction, or when power generation is executed and the temperature of the solid oxide fuel cell 100 rises, causing the seal portion 5 etc. to expand, the joint portion 51 of the seal portion 5 with the separator 3 (connection portion 31) is pressed against the separator 3 (connection portion 31), the joint portion 56 of the seal portion 5 with the joint auxiliary layer 4 is pressed against the joint auxiliary layer 4, and the joint portion 58 of the seal portion 5 with the electrolyte layer 11 is pressed against the electrolyte layer 11. Therefore, the joint portions 51, 56, and 58 are not peeled off, and a decrease in the sealing performance of the seal portion 5 can be suppressed.

[0050] [Effects of the First Embodiment] In the solid oxide fuel cell 100 of the first embodiment, a power generation cell 1 including an electrolyte layer 11, a first electrode layer (fuel electrode layer 12) disposed on one main surface of the electrolyte layer 11, and a second electrode layer (air electrode layer 13) disposed on the other main surface of the electrolyte layer 11; a support layer 2 disposed so as to sandwich the first electrode layer (fuel electrode layer 12) together with the electrolyte layer 11 and support the power generation cell 1; and a metal thin plate disposed so as to sandwich the support layer 2 together with the power generation cell 1. In the solid oxide fuel cell 100, the metal thin plate (separator 3) includes a connection portion 31 disposed so as to go around the outside of the outer shape of the power generation cell 1 in a plan view. The second electrode layer (air electrode layer 13) is disposed at the center of the other main surface of the electrolyte layer 11. A joint auxiliary layer 4, which is a mixture of a metal material and ceramics and has an airtight structure, goes around the peripheral edge of the other main surface of the electrolyte layer 11 and is disposed so as to be separated from the second electrode layer (air electrode layer 13). A seal portion 5 formed of a material containing a metal material is disposed on the connection portion 31 so as to go around the outer peripheries of the power generation cell 1 and the support layer 2. The seal portion 5 is joined at least to the side surface of the joint auxiliary layer 4 and the connection portion 31.

[0051] With the above configuration, since the joining auxiliary layer 4 has an airtight structure, the joining strength with the seal portion 5 is ensured. Further, since the seal portion 5 contains metal, the joining strength with the metal thin plate (separator 3) is also ensured. And, since the seal portion 5 is joined so as to connect the metal thin plate (separator 3) and the joining auxiliary layer 4, it is possible to suppress a decrease in the sealing performance while sealing the side surfaces of the power generation cell 1 and the support layer 2. Also, since the joining auxiliary layer 4 is separated from the second electrode layer (air electrode layer 13) as well, it is possible to ensure the insulation between the first electrode layer (fuel electrode layer 12) and the second electrode layer (air electrode layer 13). As described above, it is possible to simultaneously satisfy the strength, sealing performance, and insulation of the joint portion between different materials of the power generation cell 1 and the metal thin plate (separator 3).

[0052] Note that the joining auxiliary layer 4 is disposed on the main surface of the electrolyte layer 11 where the second electrode layer (air electrode layer 13) is disposed, and the joining auxiliary layer 4 and the second electrode layer (air electrode layer 13) are disposed at the same position in the thickness direction. Therefore, it is possible to suppress an increase in the thickness dimension of the solid oxide fuel cell 100 accordingly.

[0053] In the present embodiment, the seal portion 5 and the metal thin plate (separator 3) are made of a metal material containing aluminum. When the seal portion 5 and the metal thin plate (separator 3) are formed of stainless steel (SUS), a layer of chromium oxide (Cr 2 O 3 ) is formed on the surface of the stainless steel. However, when the chromium component detaches from the layer of chromium oxide and adheres to the second electrode layer (air electrode layer 13), the chromium component may damage the catalyst of the second electrode layer (air electrode layer 13) and reduce the power generation efficiency of the power generation cell 1. Therefore, by adding aluminum (Al) to the stainless steel at a predetermined concentration (2 to 6 wt%), a layer of aluminum oxide (Al 2 O 3 ) is formed on the layer of chromium oxide (Cr 2 O 3 ), so that detachment of the chromium component can be prevented and damage to the catalyst of the second electrode layer (air electrode layer 13) can be reduced.

[0054] In this embodiment, the seal portion 5 is arranged so as to cover the main surface of the joining auxiliary layer 4. As a result, when the solid oxide fuel cell 100 is stacked, the joint portion 51 between the seal portion 5 and the metal thin plate (separator 3 (connection portion 31)) and the joint portion 56 between the seal portion 5 and the upper surface of the joining auxiliary layer 4 are pressed from the thickness direction of the power generation cell 1, and are pressed in a direction in which the joint strength is increased. Therefore, it is possible to suppress a decrease in the sealing performance of the seal portion 5.

[0055] In this embodiment, the seal portion 5 is arranged so as to cover up to a position inside the joining auxiliary layer 4 of the electrolyte layer 11 in a plan view. As a result, for example, even if a force that curves the power generation cell 1 in the thickness direction is applied, at least the sealing performance (a state in which gases do not flow into each other) between the space (first flow path 61) on the fuel electrode layer 12 side and the space (second flow path 62) on the air electrode layer 13 side can be maintained.

[0056] In this embodiment, the support layer 2 is made of a metal material (stainless steel) containing chromium that forms a passivation film on the surface. As a result, it is possible to form the support layer 2 that is difficult to corrode.

[0057] In this embodiment, in the joining auxiliary layer 4, the blending ratio of the ceramics is higher the closer it is to the electrolyte layer 11, and the blending ratio of the metal is higher the farther it is from the electrolyte layer 11. As a result, the joint strength between the joining auxiliary layer 4 (first layer 41) and the electrolyte layer 11 and the joint strength between the joining auxiliary layer 4 (second layer 42) and the seal portion 5 can be ensured.

[0058] In this embodiment, the ceramics constituting the joining auxiliary layer 4 are of the same type as the ceramics constituting the electrolyte layer 11 and contain zirconium oxide (ZrO 2 ). As a result, the joint strength between the joining auxiliary layer 4 (first layer 41) and the electrolyte layer 11 can be ensured.

[0059] In this embodiment, the metal material constituting the joining auxiliary layer 4 is of the same type as the metal material of the seal portion 5 and includes aluminum (Al). As a result, the joint strength between the joining auxiliary layer 4 (second layer 42) and the seal portion 5 can be ensured.

[0060] According to the manufacturing method of the solid oxide fuel cell 100 of the present embodiment, a power generation cell 1 including an electrolyte layer 11, a first electrode layer (fuel electrode layer 12) disposed on one main surface of the electrolyte layer 11, and a second electrode layer (air electrode layer 13) disposed on the other main surface of the electrolyte layer 11, a support layer 2 attached to the first electrode layer (fuel electrode layer 12) and supporting the power generation cell 1, and a metal thin plate (separator 3) attached to the support layer 2. In the manufacturing method of the solid oxide fuel cell 100, the metal thin plate is formed to include a connection portion 31 that circulates outside the outer shape of the power generation cell 1 in a plan view, the second electrode layer (air electrode layer 13) is disposed at the center of the other main surface of the electrolyte layer 11, and a bonding auxiliary layer 4 that is a mixture of a metal material and ceramics and has an airtight structure is disposed so as to circulate around the peripheral edge of the other main surface of the electrolyte layer 11 and be separated from the second electrode layer (air electrode layer 13). By laminating a large number of thin films of the metal material on the connection portion 31, a seal portion 5 joined to at least the side surface of the bonding auxiliary layer 4 and the connection portion 31 is formed.

[0061] According to the above manufacturing method, since the seal portion 5 and the separator 3 (connection portion 31) are melt-connected to each other, the bonding strength (i.e., the sealing performance) of the joint portion 51 of the seal portion 5 and the separator 3 is ensured. Also, since the joint portion 52 between the seal portion 5 and the outer side surface of the bonding auxiliary layer 4 is also substantially a melt-connection between metals, the bonding strength (i.e., the sealing performance) of the joint portion 52 is ensured.

[0062] In addition, since the seal portion 5 is formed after forming an integrated body composed of the power generation cell 1, the support layer 2, and the separator 3, even if there are shape variations in the power generation cell 1, the seal portion 5 can be formed in a manner that offsets the variations, so the manufacturing yield of the solid oxide fuel cell 100 can be increased.

[0063] In the solid oxide fuel cell 100 formed by the above manufacturing method, since the joining auxiliary layer 4 has an airtight structure, the joining strength with the seal portion 5 is ensured. Further, since the seal portion 5 contains a metal, the joining strength with the metal thin plate (separator 3) is also ensured. And, since the seal portion 5 is joined so as to connect the metal thin plate (separator 3) and the joining auxiliary layer 4, it is possible to suppress a decrease in the sealing performance while sealing the side surfaces of the power generation cell 1 and the support layer 2. Also, since the joining auxiliary layer 4 is separated from the second electrode layer (air electrode layer 13) as well, it is possible to ensure the insulation between the first electrode layer (fuel electrode layer 12) and the second electrode layer (air electrode layer 13). From the above, it is possible to simultaneously satisfy the strength, the sealing performance, and the insulation of the joint portion between different materials formed by the power generation cell 1 and the metal thin plate (separator 3).

[0064] [Second Embodiment] FIG. 4 is a cross-sectional view of the solid oxide fuel cell 100 according to the second embodiment. The solid oxide fuel cell 100 according to the second embodiment is similar to the first embodiment, but in the inner seal portion 59 which is the portion inside the electrolyte layer 11 in a plan view among the seal portions 5 and which joins to the electrolyte layer 11 and the joining auxiliary layer 4, in addition to the metal material, it contains ceramics (for example, zirconium oxide (ZrO 2 )). Thereby, it is possible to ensure the joining strength of the joint portion 58 of the inner seal portion 59 with the electrolyte layer 11 and the joining strength of the joint portion 57 of the inner side surface of the inner seal portion 59 with the joining auxiliary layer 4, respectively. Note that the mixing ratio of the metal and the ceramics in the inner seal portion 59 may be 1:1.

[0065] Also, in the second embodiment, for example, an insulator spacer 7 is arranged at the connection portion 31, and another solid oxide fuel cell 100 is stacked on the solid oxide fuel cell 100, and this is repeated to form a multi-stage stack structure.

[0066] As shown in FIG. 4, an auxiliary electrode layer 131 (which may be omitted) is disposed on the air electrode layer 13 of the solid oxide fuel cell 100 disposed in the lower stage. The auxiliary electrode layer 131 (or the air electrode layer 13) is in contact with the separator 3 of the solid oxide fuel cell 100 disposed in the upper stage. The separator 3 is electrically connected to the fuel electrode layer 12 via the support layer 2.

[0067] That is, the air electrode layer 13 of the solid oxide fuel cell 100 disposed in the lower stage and the fuel electrode layer 12 of the solid oxide fuel cell 100 disposed in the upper stage are short-circuited. Therefore, by adopting the multi-stage stack structure as described above, all the solid oxide fuel cells 100 are electrically connected in series.

[0068] Also, as shown in FIG. 4, the air electrode layer 13, the electrolyte layer 11, the seal portion 5, the separator 3, and the spacer 7 of the solid oxide fuel cell 100 disposed in the lower stage communicate with the air electrode layer 13 of the solid oxide fuel cell 100 disposed in the lower stage by the separator 3 of the solid oxide fuel cell 100 disposed in the upper stage, and a second flow path 62 spatially separated from the fuel electrode layer 12 (first flow path 61) of the solid oxide fuel cell 100 disposed in the upper stage is formed.

[0069] Note that, as shown in FIG. 4, a closed space is formed by the auxiliary electrode layer 131, the air electrode layer 13, the electrolyte layer 11, the seal portion 5 (insulating material 504 described later), the separator 3 (connection portion 31), and the spacer 7 of the solid oxide fuel cell 100 disposed in the lower stage and the separator 3 of the solid oxide fuel cell 100 disposed in the upper stage, and the second flow path 62 is included in the closed space.

[0070] The seal portion 5 is connected to the separator 3 via the joint portion 51, but faces another separator 3 different from the separator 3 when a stack structure is adopted. That is, the seal portion 5 is disposed between the separator 3 connected via the joint portion 51 and another separator 3 different from (electrically insulated from) the separator 3.

[0071] Correspondingly, the surface of the seal portion 5 is covered with an insulating material 504. As the insulating material 504, aluminum oxide (Al 2 O 3 ) or zirconium oxide (ZrO 2 ) is applied. Thereby, a short circuit between the seal portion 5 of the solid oxide fuel cell 100 disposed in the lower stage and the separator 3 of the solid oxide fuel cell 100 disposed in the upper stage can be avoided.

[0072] In the second embodiment, the spacer 7 may be disposed between the seal portion 5 (insulating material 504) of the solid oxide fuel cell 100 disposed in the lower stage and the separator 3 of the solid oxide fuel cell 100 disposed in the upper stage. Further, the spacer 7 may be omitted and the seal portion 5 (insulating material 504) of the solid oxide fuel cell 100 disposed in the lower stage and the separator 3 of the solid oxide fuel cell 100 disposed in the upper stage may be joined.

[0073] [Effects of the Second Embodiment] According to the solid oxide fuel cell 100 of the second embodiment, the metal thin plate (separator 3) and the seal portion 5 communicate with the first electrode layer (fuel electrode layer 12) and form a first flow path 61 spatially separated from the second electrode layer (air electrode layer 13). When a plurality of integrated bodies including the power generation cell 1, the support layer 2, and the metal thin plate (separator 3) are laminated, the metal thin plate (separator 3) of one of a pair of adjacent integrated bodies (for example, the solid oxide fuel cell 100 disposed in the upper stage in FIG. 4) communicates with the second electrode layer (air electrode layer 13) of the other of the pair of integrated bodies (for example, the solid oxide fuel cell 100 disposed in the lower stage in FIG. 4) and forms a second flow path 62 spatially separated from the first flow path 61 formed in one of the integrated bodies (for example, the solid oxide fuel cell 100 disposed in the upper stage in FIG. 4).

[0074] With the above configuration, the second flow path 62 can be formed by stacking the solid oxide fuel cells 100 in a stack structure without previously forming the second flow path 62. Therefore, the dimension (pitch width) in the thickness direction of the solid oxide fuel cell 100 can be reduced accordingly, and the height of the stack structure can be suppressed.

[0075] In the second embodiment, the surface of the seal portion 5 is covered with an insulating material 504 made of aluminum oxide or zirconium oxide. Thereby, in the stack structure described above, a short circuit between the metal thin plate (separator 3) of one of a pair of integrated objects adjacent to each other (for example, the solid oxide fuel cell 100 disposed in the upper stage of FIG. 4) and the seal portion 5 of the other of the pair of integrated objects adjacent to each other (for example, the solid oxide fuel cell 100 disposed in the lower stage of FIG. 4) can be avoided.

[0076] Although the embodiments of the present invention have been described above, the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. Also, the above embodiments can be combined as appropriate.

Explanation of reference numerals

[0077] 100 Solid oxide fuel cell, 1 Power generation cell, 11 Electrolyte layer, 12 Fuel electrode layer, 13 Air electrode layer, 2 Support layer, 3 Separator, 4 Bonding auxiliary layer, 5 Seal portion

Claims

1. A power generation cell including an electrolyte layer, a first electrode layer disposed on one main surface of the electrolyte layer, and a second electrode layer disposed on the other main surface of the electrolyte layer; A support layer disposed to sandwich the first electrode layer together with the electrolyte layer and supporting the power generation cell; In a solid oxide fuel cell including a metal thin plate disposed to sandwich the support layer together with the power generation cell, The metal thin plate includes a connection portion disposed to surround the outside of the outer shape of the power generation cell in a plan view; The second electrode layer is disposed at the center of the other main surface of the electrolyte layer; A joining auxiliary layer, which is a mixture of a metal material and ceramics and has an airtight structure, surrounds the peripheral edge of the other main surface of the electrolyte layer and is disposed so as to be separated from the second electrode layer; A seal portion formed of a material containing a metal material is disposed in the connection portion so as to surround the outer periphery of the power generation cell and the support layer; The solid oxide fuel cell in which the seal portion is joined to at least the side surface of the joining auxiliary layer and the connection portion.

2. The metal thin plate and the seal portion form a first flow path that communicates with the first electrode layer and is spatially separated from the second electrode layer, When a plurality of integrated bodies including the power generation cell, the support layer, and the metal thin plate are stacked, one of the metal thin plates of a pair of adjacent integrated bodies communicates with the second electrode layer of the other of the pair of integrated bodies and forms a second flow path that is spatially separated from the first flow path formed in one of the integrated bodies. The solid oxide fuel cell according to Claim 1.

3. The solid oxide fuel cell according to Claim 1 or Claim 2, wherein the seal portion and the metal thin plate are made of a metal material containing aluminum.

4. The solid oxide fuel cell according to any one of Claims 1 to 3, wherein the seal portion is disposed so as to cover the main surface of the joining auxiliary layer.

5. The solid oxide fuel cell according to any one of Claims 1 to 3, wherein the seal portion is disposed so as to cover up to a position inside the joining auxiliary layer of the electrolyte layer in a plan view.

6. The solid oxide fuel cell according to Claim 5, wherein a portion of the seal portion that is inside the joining auxiliary layer of the electrolyte layer in a plan view is of the same type as the ceramics constituting the electrolyte layer and contains zirconium oxide.

7. The solid oxide fuel cell according to any one of claims 1 to 6, wherein the surface of the seal portion is coated with an insulating material made of aluminum oxide or zirconium oxide.

8. The solid oxide fuel cell according to any one of claims 1 to 7, wherein the support layer is made of a metal material containing chromium that forms a passive film on the surface.

9. The solid oxide fuel cell according to any one of claims 1 to 8, wherein the joining auxiliary layer has a higher ceramic blending ratio the closer it is to the electrolyte layer, and a higher metal blending ratio the farther it is from the electrolyte layer.

10. The solid oxide fuel cell according to claim 9, wherein the ceramic constituting the joining auxiliary layer is of the same type as the ceramic constituting the electrolyte layer and contains zirconium oxide.

11. The solid oxide fuel cell according to claim 9 or 10, wherein the metal material constituting the joining auxiliary layer is of the same type as the metal material of the seal portion and includes aluminum.

12. A power generation cell including an electrolyte layer, a first electrode layer disposed on one main surface of the electrolyte layer, and a second electrode layer disposed on the other main surface of the electrolyte layer; A support layer attached to the first electrode layer for supporting the power generation cell; A method for manufacturing a solid oxide fuel cell including a metal thin plate attached to the support layer, the method comprising: Forming the metal thin plate to include a connection portion that circulates outside the outer shape of the power generation cell in a plan view; Disposing the second electrode layer at the central portion of the other main surface of the electrolyte layer; Arranging a joining auxiliary layer, which is a mixture of a metal material and a ceramic and has an airtight structure, to circulate around the peripheral portion of the other main surface of the electrolyte layer and be spaced apart from the second electrode layer; A method for manufacturing a solid oxide fuel cell, wherein a plurality of thin films of a metal material are laminated on the connection portion to form a seal portion joined to at least the side surface of the joining auxiliary layer and the connection portion.

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