Solid oxide fuel cell and method for manufacturing same

Abstract

This solid oxide fuel cell includes a battery laminate and gas seal parts for sealing outer peripheral ends of the battery laminate. The battery laminate includes: an electrolyte layer; an anode electrode layer and a cathode electrode layer disposed so as to sandwich the electrolyte layer therebetween; a cathode support disposed on the cathode electrode layer and including stainless steel; and a cathode junction layer disposed between the cathode electrode layer and the cathode support. The interfacial strength between the cathode junction layer and the cathode electrode layer is greater than the interfacial strength between the cathode support and the cathode junction layer.

Description

Solid oxide fuel cell and manufacturing method thereof

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

[0002] Metal-supported fuel cells are known as solid oxide fuel cells. A metal-supported fuel cell is a solid oxide fuel cell provided with a metal support. In a metal-supported fuel cell, an electrolyte layer is sandwiched between an anode electrode layer and a cathode electrode layer. Furthermore, a metal support is provided on at least one of the anode electrode layer and the cathode electrode layer.

[0003] In relation to metal-supported batteries, Patent Document 1 (U.S. Pat. No. 7,553,573) discloses a composite including a porous electrically conductive layer, a porous ion-conducting layer containing an electrocatalyst provided thereon, a dense ion-conducting layer provided thereon, and an electrode provided thereon. Patent Document 1 describes that the composite is used as a solid oxide fuel cell, and that the porous electrically conductive layer is made of a metal or alloy.

[0004] The present inventors have been studying metal-supported batteries, which have a configuration in which a metal support (cathode support) is provided on a cathode electrode layer. However, it has been found that cracks may occur between the cathode electrode layer and the cathode support in such batteries. When cracks occur, the area contributing to power generation is reduced, and the performance of the battery is reduced.

[0005] Therefore, an object of the present invention is to provide a technology that can suppress the deterioration of battery performance due to cracks.

[0006] In one aspect, a solid oxide fuel cell according to the present invention includes a battery stack and a gas seal that seals the outer peripheral edge of the battery stack. The battery stack includes an electrolyte layer, an anode electrode layer and a cathode electrode layer arranged to sandwich the electrolyte layer, a cathode support member that is arranged on the cathode electrode layer and includes stainless steel, and a cathode junction layer that is arranged between the cathode electrode layer and the cathode support. The interfacial strength between the cathode junction layer and the cathode electrode layer is greater than the interfacial strength between the cathode support member and the cathode junction layer.

[0007] In one aspect, a method for producing a solid oxide fuel cell according to the present invention includes the steps of preparing an electrolyte green sheet, an anode electrode layer green sheet, a cathode electrode layer green sheet, a cathode support green sheet, and a cathode junction layer green sheet; stacking the anode electrode layer green sheet, the electrolyte green sheet, the cathode electrode layer green sheet, the cathode junction layer green sheet, and the cathode support green sheet to obtain a green sheet laminate; and firing the green sheet laminate.

[0008] FIG. 1 is a schematic cross-sectional view showing a solid oxide fuel cell according to a first embodiment. FIG. 2A is a schematic cross-sectional view showing a solid oxide fuel cell according to a reference example. FIG. 2B is a schematic cross-sectional view showing a solid oxide fuel cell according to the first embodiment. FIG. 3A is a schematic diagram showing the structure of the interface between two layers formed by particles of approximately the same size. FIG. 3B is a schematic diagram showing the structure of the interface between two layers formed by particles of different sizes. FIG. 4 is a schematic cross-sectional view showing a solid oxide fuel cell according to a second embodiment. FIG. 5 is a schematic cross-sectional view showing a solid oxide fuel cell according to a third embodiment. FIG. 6 is a flowchart showing a method for manufacturing a solid oxide fuel cell. FIG. 7 is a graph showing the measurement results of the change in current density over time during operation.

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

[0010] 1 is a schematic cross-sectional view showing a solid oxide fuel cell 1 according to this embodiment. The solid oxide fuel cell 1 has a cell stack 2 and a gas seal portion 3.

[0011] The battery stack 2 is the part that realizes the power generation function. The battery stack 2 has an anode electrode layer 6, an electrolyte layer 4, a cathode electrode layer 5, a cathode junction layer 8, and a cathode support 7. These are stacked in this order. In other words, the anode electrode layer 6 and the cathode electrode layer 5 are arranged to sandwich the electrolyte layer 4. The cathode support 7 is arranged on the cathode electrode layer 5, with the cathode junction layer 8 interposed between them. The cathode support 7 contains stainless steel.

[0012] The gas seal 3 seals the outer peripheral edge of the battery stack 2. The gas seal 3 is provided to separate gases between the anode and cathode.

[0013] During operation, a fuel gas containing hydrogen is supplied to the anode electrode layer 6. An oxygen-containing gas such as air is supplied to the cathode electrode layer 5 via the cathode support 7 and the cathode junction layer 8. Then, an electrochemical reaction proceeds in the anode electrode layer 6 and the cathode electrode layer 5, and the solid oxide fuel cell 1 generates electricity.

[0014] In this embodiment, as described above, the cathode contact layer 8 is provided between the cathode electrode layer 5 and the cathode support 7. The interfacial strength between the cathode contact layer 8 and the cathode electrode layer 5 is greater than the interfacial strength between the cathode support 7 and the cathode contact layer 8. This configuration can suppress deterioration of battery performance due to cracks. This point will be described below with reference to the Reference Examples.

[0015] FIG. 2A is a schematic cross-sectional view showing a solid oxide fuel cell according to a reference example. In this cell, a cathode junction layer 8 is not provided. That is, the cathode support 7 and the cathode electrode layer 5 are in direct contact with each other. During operation, as described above, a fuel gas containing hydrogen is supplied to the anode electrode layer 6. Furthermore, an oxygen-containing gas, such as air, is supplied to the cathode electrode layer 5 via the cathode support 7. Ideally, the presence of the gas seal 3 blocks gas between the anode and cathode. However, in practice, it is difficult to completely block gas. Therefore, hydrogen contained in the anode electrode layer 6 may pass between the gas seal 3 and the end of the electrolyte layer 4 and flow into the cathode side. The hydrogen that flows into the cathode side is combusted by oxygen. As described above, the cathode support 7 contains stainless steel. Therefore, the surface of the cathode support 7 is oxidized, and Fe ３ O ４ is formed. ３ O ４ The cathode support 7 often has a thermal expansion coefficient significantly different from that of the material (typically zirconia) that constitutes the cathode electrode layer 5. This can cause thermal stress between the cathode support 7 and the cathode electrode layer 5, which can cause the cathode support 7 to peel off from the cathode electrode layer 5. In other words, cracks can occur. Cracks usually start at the outer periphery of the battery stack 2 and progress inward (see the arrows in Figure 2A). Resistance becomes very high in the area where a crack occurs, and almost no current flows in the cathode electrode layer 5. This reduces the area of ​​the portion that contributes to power generation, resulting in a decrease in battery performance.

[0016] 2B is a schematic cross-sectional view showing the solid oxide fuel cell 1 according to this embodiment, illustrating the configuration during operation. In this embodiment, as described above, the cathode junction layer 8 is provided, and the interfacial strength between the cathode junction layer 8 and the cathode electrode layer 5 is greater than the interfacial strength between the cathode support 7 and the cathode junction layer 8. Therefore, even if a crack occurs, it will occur between the cathode support 7 and the cathode junction layer 8, which has a lower interfacial strength. The cathode junction layer 8 can be formed from a material with higher electronic conductivity than the cathode electrode layer 5. Therefore, even if a crack occurs between the cathode support 7 and the cathode junction layer 8, current will flow in the in-plane direction (perpendicular to the stacking direction) in the cathode junction layer 8, and the area of ​​the portion contributing to power generation will not decrease significantly. This prevents performance degradation due to cracking.

[0017] The above is an outline of this embodiment. Next, the detailed configuration of this embodiment will be described in detail.

[0018] (Electrolyte Layer) The electrolyte layer 4 may be configured to be oxide ion conductive but gas impermeable. Preferably, the electrolyte layer 4 is made of dense ceramics. For example, the electrolyte layer 4 may be made of solid oxide ceramics. Examples of solid oxide ceramics include, but are not limited to, zirconia-containing materials and perovskite oxides. Examples of zirconia-containing materials include stabilized zirconia doped with yttria, neodymium oxide, samarium, gadolinium, scandium, and the like. The thickness of the electrolyte layer 4 is, for example, 0.5 to 20 μm, preferably 1 to 10 μm.

[0019] (Cathode Electrode Layer and Anode Electrode Layer) The cathode electrode layer 5 is a layer that converts oxygen molecules contained in an oxygen-containing gas into oxide ions, while the anode electrode layer 6 is a layer that reacts a fuel such as hydrogen with the oxide ions to generate electrons.

[0020] The cathode electrode layer 5 and the anode electrode layer 6 are formed of, for example, porous ceramics. Examples of porous ceramics include solid oxide ceramics. Examples of solid oxide ceramics include zirconia and perovskite oxide. Examples of zirconia include stabilized zirconia doped with yttria, neodymium oxide, samarium, gadolinium, scandium, or the like.

[0021] The thickness of each of the cathode electrode layer 5 and the anode electrode layer 6 is, for example, 0.3 to 50 μm, preferably 0.5 to 30 μm.

[0022] A cathode catalyst for promoting the electrode reaction may be supported on the cathode electrode layer 5. Examples of the cathode catalyst include praseodymium oxide.

[0023] An anode catalyst for promoting the electrode reaction may also be supported on the anode electrode layer 6. Examples of such anode catalyst include nickel (Ni), palladium (Pd), platinum (Pt), ruthenium (Ru), Ni—Fe alloy, Ni—Co alloy, Fe—Co alloy, Ni—Cu alloy, and Pd—Pt alloy.

[0024] (Cathode Support) The cathode support 7 is provided for the purpose of maintaining the shape, etc. The thickness of the cathode support 7 is determined from the viewpoint of maintaining the shape, etc., and is, for example, 50 to 1000 μm, preferably 100 to 500 μm.

[0025] As described above, the cathode support 7 contains stainless steel. Preferably, most of the constituent material of the cathode support 7 is stainless steel. For example, 95 mass % or more of the cathode support 7 is stainless steel. More preferably, 99 mass % or more of the cathode support 7 is stainless steel. If the cathode support 7 contains stainless steel, as described above, the surface of the cathode support 7 may oxidize and cracks may occur. However, according to this embodiment, as described above, the power generation area is ensured even if cracks occur, and therefore performance degradation due to cracks can be suppressed.

[0026] The cathode support 7 has gas permeability. Specifically, the cathode support 7 has a porous structure. For example, the cathode support 7 is formed of an aggregate of particulate matter. This makes it possible to supply an oxygen-containing gas to the cathode electrode layer 5 from the outside through the cathode support 7.

[0027] (Cathode Bonding Layer) As described above, the cathode bonding layer 8 is provided to control the location of crack generation.

[0028] The volume resistivity of the cathode junction layer 8 is preferably smaller than the volume resistivity of the cathode electrode layer 5. With this configuration, current flows more easily in the planar direction in the cathode junction layer 8, so that a power generation region is ensured even if cracks occur. Preferably, the volume resistivity of the cathode junction layer 8 is 1 / 10 or less of the volume resistivity of the cathode electrode layer 5.

[0029] There are no particular limitations on the constituent material of the cathode junction layer 8. Any material may be used so that the interfacial strength between the cathode junction layer 8 and the cathode electrode layer 5 is greater than the interfacial strength between the cathode support 7 and the cathode junction layer 8.

[0030] In a preferred embodiment, the cathode junction layer 8 contains stainless steel. Stainless steel has excellent electronic conductivity. The inclusion of stainless steel makes it easy to reduce the volume resistivity of the cathode junction layer 8. For example, 95% by mass or more of the cathode junction layer 8 is stainless steel. Preferably, 99% by mass or more of the cathode junction layer 8 is stainless steel.

[0031] Alternatively, the cathode bonding layer 8 preferably contains a cermet of stainless steel and a ceramic containing zirconia. The inclusion of stainless steel facilitates reducing the volume resistivity of the cathode bonding layer 8, as described above. Furthermore, when the cathode electrode layer 5 contains zirconia, if the cathode bonding layer 8 also contains zirconia, the interfacial strength between the cathode bonding layer 8 and the cathode electrode layer 5 is likely to increase due to interdiffusion. Therefore, a configuration in which the interfacial strength between the cathode bonding layer 8 and the cathode electrode layer 5 is greater than the interfacial strength between the cathode support 7 and the cathode bonding layer 8 is likely to be obtained.

[0032] The cathode junction layer 8 preferably has a porous structure that is gas permeable. In a preferred embodiment, the cathode support 7 and the cathode junction layer 8 are each formed of particles. The average particle diameter of the cathode support 7 is larger than the average particle diameter of the cathode junction layer 8. By adopting such a configuration, the location of crack generation can be more reliably controlled. This point will be described with reference to FIGS. 3A and 3B.

[0033] FIG. 3A is a schematic diagram showing the structure of the interface between two layers formed with particles of similar sizes. Meanwhile, FIG. 3B is a schematic diagram showing the structure of the interface between two layers formed with particles of different sizes. As shown in FIG. 3A , when the particle sizes are similar, the bonding area at the interface increases, thereby increasing the interfacial strength between the two layers. On the other hand, as shown in FIG. 3B , when the particle sizes are different, the two layers are bonded by point contact, resulting in low interfacial strength. If the average particle diameter of the cathode support 7 is larger than the average particle diameter of the cathode junction layer 8, as shown in FIG. 3B , the cathode support 7 and the cathode junction layer 8 are bonded by point contact, resulting in low interfacial strength. As a result, cracks can be selectively propagated at the interface between the cathode support 7 and the cathode junction layer 8, preventing cracks from occurring in unintended areas. In other words, the location of crack occurrence can be more reliably controlled. This more reliably prevents degradation of battery performance.

[0034] In this specification, the average particle diameters of the cathode support 7 and the cathode junction layer 8 can be determined by observing the cross section with a microscope. For example, a micrograph of the cross section of the solid oxide fuel cell is obtained, and image analysis is performed to calculate the circle-equivalent diameter of each particle, and the number average thereof is calculated, thereby determining the average particle diameter.

[0035] The thickness of the cathode junction layer 8 is preferably 1 / 10 to 1 / 2 of the thickness of the cathode support 7. The thicker the cathode junction layer 8, the more easily current flows in the surface direction of the cathode junction layer 8. As a result, it becomes easier to suppress deterioration of battery performance due to cracks. On the other hand, if the thickness of the cathode junction layer 8 is small, cracks tend to occur selectively at the interface between the cathode junction layer 8 and the cathode support 7, and it becomes possible to suppress cracks from occurring in unintended areas. In other words, it becomes easier to control the location of crack occurrence. If the thickness of the cathode junction layer 8 is within the above-mentioned range, it becomes possible to sufficiently control the location of crack occurrence while sufficiently suppressing deterioration of the power generation region.

[0036] (Gas Seal Portion) The gas seal portion 3 may be configured to have a gas blocking function, and may be made of, for example, a glass material.

[0037] (2) Second Embodiment Next, a second embodiment will be described. Detailed description will be omitted for the points where the same configuration as the above-described embodiment can be adopted.

[0038] 4 is a schematic cross-sectional view showing a solid oxide fuel cell 1 according to this embodiment. In this embodiment, the size of the cathode junction layer 8 is specified. Specifically, when viewed along the stacking direction, the end of the cathode junction layer 8 is located more inward than the end of the cathode support 7. Note that the ends of the cathode electrode layer 5, electrolyte layer 4, and anode electrode layer 6 are aligned when viewed along the stacking direction. As a result, outside the cathode junction layer 8, the cathode support 7 and the cathode electrode layer 5 are in direct contact with each other.

[0039] According to this embodiment, the crack propagation position can be more reliably controlled. The interfacial strength between the cathode electrode layer 5 and the cathode support 7 is relatively small. Therefore, cracks propagate inward from the interface between the cathode electrode layer 5 and the cathode support 7 at the outer peripheral edge of the battery stack 2. Cracks that propagate inward are guided upward (to the interface between the cathode contact layer 8 and the cathode support 7) at the outer peripheral edge of the cathode contact layer 8. This makes it easier to limit the location of crack generation to between the cathode support 7 and the cathode contact layer 8. Since crack generation in unintended areas is more reliably prevented, deterioration of battery performance can be more reliably suppressed.

[0040] (3) Third Embodiment Next, a third embodiment will be described. Detailed description will be omitted for the fact that the same configuration as the previously described embodiments can be adopted.

[0041] 5 is a schematic cross-sectional view showing a solid oxide fuel cell 1 according to this embodiment. In this embodiment, the cell stack 2 further includes an anode support 9. The anode support 9 is provided on the anode electrode layer 6. As the anode support 9, for example, one having the same configuration as the cathode support 7 can be used.

[0042] According to this embodiment, the solid oxide fuel cell 1 has a symmetrical configuration in the stacking direction centered on the electrolyte layer 4. Therefore, distortion is less likely to occur in the solid oxide fuel cell 1, and a flat configuration can be achieved.

[0043] (4) Manufacturing Method Next, a method for manufacturing the solid oxide fuel cell 1 will be described. Fig. 6 is a flowchart showing the method for manufacturing the solid oxide fuel cell 1.

[0044] Step S1: Preparation of Green Sheets First, green sheets that serve as precursors for each part are prepared. Specifically, a green sheet for the electrolyte, a green sheet for the anode electrode layer, a green sheet for the cathode electrode layer, a green sheet for the cathode support, and a green sheet for the cathode junction layer are prepared. If an anode support is provided, a green sheet for the anode support is also prepared. Each green sheet can be prepared, for example, by preparing a slurry containing the constituent materials and then using a tape casting method.

[0045] Step S2: Lamination Subsequently, the anode electrode layer green sheet, the electrolyte green sheet, the cathode electrode layer green sheet, the cathode junction layer green sheet, the cathode support green sheet, and, if necessary, the anode support green sheet are laminated to obtain a green sheet laminate.

[0046] If necessary, the green sheet laminate is cut to a desired size.

[0047] Step S3: Firing (reducing atmosphere) The green sheet laminate is then fired in a reducing atmosphere to obtain a fired body. The firing temperature is, for example, 1200 to 1500°C.

[0048] Step S4: Formation of Gas Seal Portion Subsequently, a seal material is applied to cover the end portion of the fired body, and the fired body is then fired. In this way, the gas seal portion 3 is formed.

[0049] Step S5: Impregnation of electrode catalyst and heat treatment Subsequently, each electrode layer is impregnated with an electrode catalyst and heat treatment is performed. Specifically, an anode catalyst-containing liquid and a cathode catalyst-containing liquid are prepared. Then, each electrode layer is impregnated with each catalyst-containing liquid. Specifically, first, one of the anode electrode layer and the cathode electrode layer is impregnated with the catalyst-containing liquid and heat treatment is performed. Thereafter, the other of the anode electrode layer and the cathode electrode layer is impregnated with the catalyst-containing liquid and heat treatment is performed. This allows the electrode catalyst to be supported on each electrode layer.

[0050] The method described above can produce a solid oxide fuel cell 1. In the above-described method, if an appropriate material is selected for the cathode junction layer, the interfacial strength between the cathode junction layer and the cathode electrode layer in the resulting solid oxide fuel cell 1 will be greater than the interfacial strength between the cathode support and the cathode junction layer.

[0051] Next, examples carried out by the present inventors will be described, but the present invention should not be construed as being limited to the following examples.

[0052] Example 1 In Example 1, a solid oxide fuel cell having the configuration shown in FIG. 1 was fabricated. Specifically, the solid oxide fuel cell was fabricated according to the flowchart shown in FIG. 6. The electrolyte layer was made of scandium-doped stabilized zirconia. The thickness of the electrolyte layer was 10 microns. The anode electrode layer and the cathode electrode layer were made of ceramics containing zirconia. The thickness of the anode electrode layer was 20 microns. The thickness of the cathode electrode layer was 20 microns. The cathode bonding layer was made of a cermet of stainless steel powder and scandium-doped stabilized zirconia powder. The thickness of the cathode bonding layer was 10 microns. The volume resistivity of the cathode bonding layer was 1 / 10 or less of that of the cathode electrode layer. The cathode support was made of stainless steel. The thickness of the cathode support was 300 microns. The average particle diameter in the cathode bonding layer was smaller than the average particle diameter in the cathode support.

[0053] Comparative Example 1 A solid oxide fuel cell according to Comparative Example 1 was fabricated in the same manner as in Example 1, except that no cathode junction layer was used.

[0054] The solid oxide fuel cells according to Example 1 and Comparative Example 1 were operated. Specifically, air was supplied to the cathode electrode layer, and hydrogen was supplied to the anode electrode layer. The change in current density over time during operation was measured. The results are shown in FIG. 7. In FIG. 7, spectrum a is for Example 1, and spectrum b is for Comparative Example 1. As shown in FIG. 7, Example 1 showed less decrease in current density over time than Comparative Example 1. This confirmed that the provision of a cathode junction layer having a specific configuration can suppress the deterioration of cell performance.

[0055] [Additional Notes] Representative configurations and their effects in this embodiment will be summarized below as additional notes.

[0056] (Supplementary Note 1) A solid oxide fuel cell comprising: a battery stack 2; and a gas seal part 3 that seals the outer peripheral edge of the battery stack; the battery stack 2 comprising: an electrolyte layer 4; an anode electrode layer 6 and a cathode electrode layer 5 arranged to sandwich the electrolyte layer; a cathode support 7 arranged on the cathode electrode layer and including stainless steel; and a cathode junction layer 8 arranged between the cathode electrode layer and the cathode support; and the interfacial strength between the cathode junction layer 8 and the cathode electrode layer 5 is greater than the interfacial strength between the cathode support 7 and the cathode junction layer 8.

[0057] According to the above-described configuration, the location of crack generation can be controlled to the interface between the cathode support 7 and the cathode junction layer 8. This makes it possible to suppress a decrease in the power generation region and a decrease in the cell performance.

[0058] (Supplementary Note 2) The solid oxide fuel cell according to Supplementary Note 1, wherein the volume resistivity of the cathode contact layer is lower than the volume resistivity of the cathode electrode layer.

[0059] According to the above-described configuration, even if a crack occurs at the interface between the cathode support 7 and the cathode junction layer 8, a current flows in the surface direction of the cathode junction layer, thereby suppressing a decrease in the power generation area and, as a result, suppressing a decrease in the cell performance.

[0060] (Supplementary Note 3) The solid oxide fuel cell according to Supplementary Note 1 or 2, wherein the cathode junction layer includes a cermet of stainless steel and ceramics containing zirconia.

[0061] According to the above-described configuration, the use of stainless steel reduces the volume resistivity of the cathode bonding layer. Furthermore, if the cathode electrode layer contains zirconia, the interdiffusion of zirconia increases the strength of the interface between the cathode electrode layer and the cathode bonding layer. As a result, the location of crack generation can be more reliably controlled.

[0062] (Supplementary Note 4) The solid oxide fuel cell according to Supplementary Note 1 or 2, wherein the cathode junction layer contains stainless steel.

[0063] According to the above-described configuration, the volume resistivity of the cathode junction layer can be easily reduced.

[0064] (Appendix 5) The solid oxide fuel cell according to any one of Appendices 1 to 4, wherein the cathode support and the cathode junction layer are each formed of particles, and an average particle diameter of the cathode support is larger than an average particle diameter of the cathode junction layer.

[0065] According to the above-mentioned configuration, the strength of the interface between the cathode junction layer and the cathode support is reduced, so that the location of crack generation can be more reliably controlled.

[0066] (Supplementary Note 6) The solid oxide fuel cell according to any one of Supplementary Notes 1 to 5, wherein the thickness of the cathode junction layer is 1 / 10 to 1 / 2 of the thickness of the cathode support.

[0067] According to the above-described configuration, cracks are likely to be selectively generated at the interface between the cathode junction layer and the cathode support layer while sufficiently suppressing the reduction in the power generation region.

[0068] (Supplementary Note 7) The solid oxide fuel cell according to any one of Supplementary Notes 1 to 6, wherein an end of the cathode junction layer is located more inward than an end of the cathode support when viewed along the stacking direction.

[0069] According to the above-described configuration, cracks are more likely to occur between the cathode support and the cathode contact layer, which more reliably prevents cracks from occurring in unintended areas and more reliably suppresses deterioration of battery performance.

[0070] (Supplementary Note 8) The solid oxide fuel cell according to any one of Supplementary Notes 1 to 7, further comprising an anode support formed of a metal and provided on the anode electrode layer.

[0071] According to the above-described configuration, a solid oxide fuel cell having a flat configuration can be realized.

[0072] (Appendix 9) A method for producing a solid oxide fuel cell according to any one of Appendices 1 to 8, comprising the steps of: preparing an electrolyte green sheet, an anode electrode layer green sheet, a cathode electrode layer green sheet, a cathode support green sheet, and a cathode junction layer green sheet; stacking the anode electrode layer green sheet, the electrolyte green sheet, the cathode electrode layer green sheet, the cathode junction layer green sheet, and the cathode support green sheet to obtain a green sheet laminate; and firing the green sheet laminate.

[0073] According to the above-described method, it is possible to manufacture a solid oxide fuel cell in which deterioration of the cell performance due to the occurrence of cracks is suppressed.

Claims

1. A solid oxide fuel cell comprising: a battery stack; and a gas seal part that seals the outer peripheral edge of the battery stack, wherein the battery stack comprises: an electrolyte layer; an anode electrode layer and a cathode electrode layer arranged to sandwich the electrolyte layer; a cathode support member arranged on the cathode electrode layer and including stainless steel; and a cathode junction layer arranged between the cathode electrode layer and the cathode support member, wherein the interfacial strength between the cathode junction layer and the cathode electrode layer is greater than the interfacial strength between the cathode support member and the cathode junction layer.

2. The solid oxide fuel cell according to claim 1, wherein the volume resistivity of the cathode contact layer is smaller than the volume resistivity of the cathode electrode layer.

3. A solid oxide fuel cell according to claim 1 or 2, wherein the cathode junction layer contains a cermet of stainless steel and ceramics containing zirconia.

4. The solid oxide fuel cell according to claim 1 or 2, wherein the cathode junction layer contains stainless steel.

5. A solid oxide fuel cell according to claim 1 or 2, wherein the cathode support and the cathode junction layer are each formed of particles, and the average particle diameter of the cathode support is larger than the average particle diameter of the cathode junction layer.

6. A solid oxide fuel cell according to claim 1 or 2, wherein the thickness of the cathode junction layer is 1 / 10 to 1 / 2 of the thickness of the cathode support.

7. A solid oxide fuel cell according to claim 1 or 2, wherein, when viewed along the stacking direction, an end of the cathode junction layer is located inside an end of the cathode support.

8. A solid oxide fuel cell according to claim 1 or 2, further comprising an anode support formed of a metal and provided on the anode electrode layer.

9. A method for producing a solid oxide fuel cell according to claim 1, comprising the steps of: preparing an electrolyte green sheet, an anode electrode layer green sheet, a cathode electrode layer green sheet, a cathode support green sheet, and a cathode junction layer green sheet; stacking the anode electrode layer green sheet, the electrolyte green sheet, the cathode electrode layer green sheet, the cathode junction layer green sheet, and the cathode support green sheet to obtain a green sheet laminate; and firing the green sheet laminate.

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