Solid oxide fuel cell and method for manufacturing same

Abstract

This solid oxide fuel cell is provided with: a first electrode structure; an electrolyte layer laminated on the first electrode structure; and a second electrode structure. And an electrolyte layer laminated on the electrolyte layer. The first electrode structure has a first porous metal support layer and a first electrode layer. The first electrode structure is provided with: a filling part; and a first dam which is located outside the filling part when viewed in the stacking direction, and which is a portion densified so as to prevent leakage of the filling material to the outside of the filling part.

Description

Technical Field

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

[0002] A solid oxide fuel cell is a fuel cell that uses a solid material as an electrolyte. A solid oxide fuel cell generally has an electrolyte layer, an anode electrode, and a cathode electrode. The anode electrode and the cathode electrode are arranged in a manner that the electrolyte layer is separated. During power generation, anode gas is supplied to the anode electrode, and cathode gas is supplied to the cathode electrode. There is a case where a metal support layer is provided as a support on the outside of the anode electrode and / or the cathode electrode. In order to be able to supply gas from the outside to the electrode, the metal support layer needs to be permeable. Therefore, the metal support layer is generally formed of a porous material.

[0003] The metal supporting layer is porous, so there is a possibility that the supplied gas leaks from the end of the metal supporting layer. As a result, there is a possibility that the gas mixes between the two electrodes. In order to achieve efficient power generation, it is necessary to prevent the leakage of the gas at the end so that the gas is separated between the two electrodes.

[0004] In connection with the above, Patent Document 1 (JP2008-159428A) describes that a solid oxide fuel cell is manufactured using a porous body in which at least one region is filled with metallic glass to form a gas sealing region. Summary of the invention

[0005] According to the technology described in Patent Document 1, gas leakage is prevented in a gas-sealed area filled with metallic glass. However, there is a case where the solid oxide fuel cell reaches a high temperature during operation. As a result, there is a possibility that the filled metallic glass softens. In addition, there is a case where the internal pressure of any electrode becomes high due to the supply of gas during operation. As a result, there is a possibility that the softened metallic glass flows outward due to the increased internal pressure, and the gas sealing performance is impaired.

[0006] Therefore, an object of the present invention is to provide a solid oxide fuel cell whose gas sealing properties are not impaired even at high temperatures and high internal pressures, and a method for manufacturing the same.

[0007] The solid oxide fuel cell of the present invention comprises: a porous first electrode structure; an electrolyte layer, which is stacked on the first electrode structure; and a second electrode structure, which is stacked on the electrolyte layer. The first electrode structure comprises: a first porous metal supporting layer; and a first electrode layer, which is arranged between the first porous metal supporting layer and the electrolyte layer. A filling portion and a first dam are provided in the first electrode structure. The filling portion is an area where the pores are filled with a filling material. The filling portion is provided in a ring-shaped manner when viewed along the stacking direction. The first dam is located outside the filling portion when viewed along the stacking direction. The first dam is a portion that is densified to prevent the filling material from leaking to the outside of the filling portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a top view of the solid oxide fuel cell according to the first embodiment.

[0009] Figure 2 It is a cross-sectional view showing the solid oxide fuel cell according to the first embodiment.

[0010] Figure 3 This is a schematic cross-sectional view showing a solid oxide fuel cell during the manufacturing process.

[0011] Figure 4 This is a schematic cross-sectional view showing a solid oxide fuel cell during the manufacturing process.

[0012] Figure 5 This is a schematic cross-sectional view showing a solid oxide fuel cell during the manufacturing process.

[0013] Figure 6 This is a schematic cross-sectional view showing a solid oxide fuel cell during the manufacturing process.

[0014] Figure 7 This is a schematic cross-sectional view showing a solid oxide fuel cell during the manufacturing process.

[0015] Figure 8 This is a schematic cross-sectional view showing an end portion of a solid oxide fuel cell according to a second embodiment. DETAILED DESCRIPTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0017] [First embodiment]

[0018] Figure 1 This is a diagram showing a state where the cell units of the solid oxide fuel cell 1 according to the first embodiment are viewed along the stacking direction, that is, a plan view of the solid oxide fuel cell. Figure 2 is a cross-sectional view showing a solid oxide fuel cell 1 and Figure 1 Figure AA section in.

[0019] like Figure 1 and Figure 2 As shown, the solid oxide fuel cell 1 schematically includes a metal frame 7, a stack 5, and a seal 6. The stack 5 is supported by the metal frame 7. The seal 6 is provided so as to cover the end of the stack 5.

[0020] The stack 5 has an electrolyte layer 2, a first electrode structure 3, and a second electrode structure 4. They are stacked. That is, the electrolyte layer 2 is stacked on the first electrode structure 3, and the second electrode structure 4 is stacked on the electrolyte layer 2. In other words, the electrolyte layer 2 is sandwiched by the first electrode structure 3 and the second electrode structure 4. One of the first electrode structure 3 and the second electrode structure 4 functions as an anode, and the other functions as a cathode. In addition, the first electrode structure 3 can also be an anode, and the second electrode structure 4 can also be an anode. During operation, anode gas is supplied to one of the first electrode structure 3 and the second electrode structure 4, and cathode gas is supplied to the other.

[0021] The stacked body 5 is supported by the metal frame 7 on the side of the first electrode structure 3. Specifically, the outer periphery of the first electrode structure 3 is located on the frame of the metal frame 7. In addition, the stacked body 5 is joined to the metal frame 7 by welding (Japanese: melting) in the outer periphery. Figure 2 In FIG. 1 , the welded portion is indicated as a welded portion 10 .

[0022] In addition, the center of the lower surface of the first electrode structure 3 is located above the opening of the metal frame 7. That is, the lower surface of the first electrode structure 3 is exposed at the center. According to such a structure, gas (anode gas or cathode gas) can be supplied to the first electrode structure 3 through the opening of the metal frame 7.

[0023] The electrolyte layer 2 is formed of a dense ceramic layer. In addition, ceramic refers to a sintered body of an inorganic substance, and is a concept that includes not only non-metallic oxides but also metal oxides. The electrolyte layer 2 may be configured in a manner that allows oxide ions to be conducted and does not allow gas to pass through. For example, the electrolyte layer 2 may be formed of a solid oxide ceramic. There is no particular limitation on the solid oxide ceramic, but for example, materials containing zirconium oxide may be cited. As materials containing zirconium oxide, stabilized zirconium oxide doped with yttrium oxide, neodymium oxide, samarium, gadolinium, and scandium may be cited. The thickness of the electrolyte layer 2 is, for example, 0.5 to 20 μm, preferably 1 to 10 μm.

[0024] The first electrode structure 3 and the second electrode structure 4 are porous structures, respectively. In addition, the first electrode structure 3 and the second electrode structure 4 are two-layer structures, respectively. Specifically, the first electrode structure 3 includes a first electrode layer 3-1 and a first porous metal supporting layer 3-2. The second electrode structure 4 includes a second electrode layer 4-1 and a second porous metal supporting layer 4-2. The first electrode layer 3-1 and the second electrode layer 4-1 are arranged in a manner of sandwiching the electrolyte layer 2 and bonded to the electrolyte layer 2. The first porous metal supporting layer 3-2 and the second porous metal supporting layer 4-2 are arranged on the outside of the first electrode layer 3-1 and the second electrode layer 4-1, respectively.

[0025] The first electrode layer 3-1 and the second electrode layer 4-1 are layers for the exchange of electrons during power generation. The first electrode layer 3-1 and the second electrode layer 4-1 are composed of porous ceramic layers. The porous ceramic layer can be formed of, for example, solid oxide ceramics. As solid oxide ceramics, for example, stabilized zirconium oxide doped with yttrium oxide, neodymium oxide, samarium, gadolinium, scandium, etc. can be cited. The thickness of the first electrode layer 3-1 and the second electrode layer 4-1 is, for example, 0.3 to 50 μm, preferably 0.5 to 30 μm.

[0026] The first porous metal supporting layer 3-2 and the second porous metal supporting layer 4-2 are provided for the purpose of shape maintenance. By providing these supporting layers, the shape can be maintained even when the thickness of the electrolyte layer 2, the first electrode layer 3-1 and the second electrode layer 4-1 is thin. The thickness of each porous metal supporting layer (3-2 and 4-2) is determined from the viewpoint of shape maintenance, for example, 50 to 1000 μm, preferably 100 to 500 μm. Each porous metal supporting layer (3-2 and 4-2) can be formed of, for example, Fe and Cr.

[0027] However, in the present embodiment, the first electrode structure 3 is provided with the filling portion 11 , the first dam 8 , and the second dam 9 .

[0028] The filling portion 11 is a region where the pores are filled with a filler. The filling portion 11 has a ring-shaped shape when viewed along the stacking direction. The filling portion 11 is provided at the outer periphery of the first electrode structure 3. Specifically, the filling portion 11 is provided in the region where the first electrode structure 3 overlaps with the metal frame 7. Therefore, the width of the filling portion 11 when viewed along the stacking direction is smaller than the width of the portion where the first electrode structure 3 overlaps with the metal frame 7.

[0029] The filling portion 11 is provided to prevent gas from leaking from the outer peripheral end portion of the first electrode structure 3. As described above, the first electrode structure 3 is porous. Therefore, in the case where the filling portion 11 is not provided, there is a possibility that the gas supplied to the first electrode structure 3 leaks to the outside from the outer peripheral end portion. In particular, the first porous metal support layer 3-2 is designed to have air permeability, so that gas easily leaks from the end portion of the first porous metal support layer 3-2. Although a seal 6 is provided at the end portion of the laminate 5, it is difficult to completely prevent gas leakage only by the seal 6. In contrast, in the present embodiment, the filling portion 11 is provided, so that the gas supplied to the first electrode structure 3 hardly leaks to the outside from the end portion.

[0030] The filling material is not particularly limited, but for example, at least one selected from the group consisting of metal powder, glass, and ceramics (such as cerium oxide and zirconium oxide) can be cited.

[0031] The filling portion 11 is preferably provided to a height (Japanese: depth) reaching from the surface (lower surface) of the first electrode structure 3 to the electrolyte layer 2. By providing the filling portion 11 at such a height, gas leakage from between the metal frame 7 and the electrolyte layer 2 to the side can be more reliably prevented. In addition, even if gas leakage cannot be completely prevented at the filling portion 11, the leakage channel is narrowed, so that the internal pressure applied to the seal 6 is reduced. Therefore, damage to the seal 6 caused by an increase in the internal pressure can be prevented, and the reliability of the sealing function at the end portion of the laminate 5 can be improved.

[0032] The first dam 8 is located outside the filling portion 11 when viewed in the stacking direction. The first dam 8 is a portion where densification is performed to prevent the filling material from leaking outside the filling portion 11. The first dam 8 is provided in a ring shape along the outer peripheral portion of the first electrode structure 3 when viewed in the stacking direction.

[0033] As described above, during the operation of the solid oxide fuel cell 1, the solid oxide fuel cell 1 may become hot. As a result, the filling material filled in the filling portion 11 may soften. In addition, gas is supplied to the first electrode structure 3, so that the internal pressure sometimes increases. In the case where the first dam 8 is not provided, there is a possibility that the fluidized filling material flows outwards as the internal pressure increases, and the function of the filling portion 11 is impaired. However, according to the present embodiment, the first dam 8 is provided, so that the filling material is intercepted. Therefore, the function in the filling portion 11, that is, the gas tightness, can be maintained even at high temperature and high internal pressure.

[0034] The first dam 8 may be densified so as not to fluidize even when the filler material is heated to a high temperature to fluidize. For example, the metal constituting the first porous metal supporting layer 3-2 is heated to melt the metal, and the pores are filled with the melted metal, thereby forming the first dam 8. For example, the first dam 8 may be formed by a weld bead of wire discharge machining or laser welding.

[0035] The second dam 9 is provided inside the filling portion 11 when viewed along the stacking direction. The second dam 9 is a portion densified to prevent the filling material from leaking inside the filling portion 11. The second dam 9 can be formed by the same method as the first dam 8. By providing the second dam 9, it is possible to prevent not only the filling material from leaking outside but also the filling material from leaking inside.

[0036] The first dam 8 and the second dam 9 are both provided in the region where the first electrode structure 3 overlaps with the metal frame 7. In addition, the first dam 8 is separated from the second dam 9. That is, the width of the first dam 8 itself and the width of the second dam 9 itself are each smaller than 0.5 times the width of the region where the first electrode structure 3 overlaps with the metal frame 7.

[0037] The first dam 8 is preferably provided at a height from the surface (lower surface) of the first electrode structure 3 to the electrolyte layer 2. By providing the first dam 8 at such a height, leakage of the filler can be more reliably prevented.

[0038] On the other hand, the second dam 9 is preferably set to a height lower than the height of the first dam 8 from the surface of the first electrode structure 3. That is, the second dam 9 preferably does not reach the electrolyte layer 2. The higher the height of the dam, the easier it is to prevent leakage of the filler. However, if the second dam 9 is formed at a height that reaches the electrolyte layer 2, the electrolyte layer 2 is sometimes damaged. As a result, there is a possibility of gas leakage through the damaged portion. In contrast, if the height of the second dam 9 is a height that does not reach the electrolyte layer 2, damage to the electrolyte layer 2 can be prevented. Therefore, gas leakage caused by damage to the electrolyte layer 2 can be prevented.

[0039] Furthermore, the first dam 8 is located in a portion surrounded by the filling portion 11 and the seal 6. Therefore, even if the electrolyte layer 2 is damaged on the first dam 8, there is little concern about gas leakage through the damaged portion. Therefore, from the viewpoint of more reliably preventing leakage of the filling material, the first dam 8 is preferably provided at a height reaching the electrolyte layer 2 as described above.

[0040] Next, the welding portion 10 will be described. As already mentioned, the stack 5 is joined to the metal frame 7 by means of the welding portion 10. Among them, the welding portion 10 is formed in a ring-shaped manner when viewed along the stacking direction. Moreover, the welding portion 10 is provided in the filling portion 11. That is, the welding portion 10 is provided between the first dam 8 and the second dam 9. By providing the welding portion 10 at such a position, it is possible to prevent the gas from leaking to the outside through the interface between the first electrode structure 3 and the metal frame 7. In addition, when the filling portion 11 is filled with metal as a filler, the weld bead constituting the welding portion 10 is more dense at the filling portion 11. Therefore, the gas is more reliably sealed at the welding portion 10.

[0041] Next, the structure of the second electrode structure 4 will be described.

[0042] like Figure 2 As shown, the second porous metal supporting layer 4-2 is not provided at the periphery of the second electrode structure 4. That is, when viewed along the stacking direction, the outer shape of the second porous metal supporting layer 4-2 is located at a position closer to the inside than the outer shapes of the second electrode layer 4-1 and the electrolyte layer 2. As a result, the second electrode layer 4-1 is exposed at the periphery of the stack 5. In addition, a seal 6 is provided in a manner covering the exposed portion of the second electrode layer 4-1 and the end of the stack 5. The exposed portion of the second electrode layer 4-1 is a portion formed by removing the second porous metal supporting layer 4-2 by etching or the like, and is rougher than the surface of the second porous metal supporting layer 4-2. According to such a structure, the seal 6 can be firmly bonded to the exposed portion of the second electrode layer 4-1 by the anchoring effect.

[0043] In addition, Figure 2 In the example shown, the second electrode layer 4 - 1 is exposed at the outer periphery. However, instead of the second electrode layer 4 - 1 , the electrolyte layer 2 may be exposed, and the exposed portion of the electrolyte layer 2 may be covered by the sealing member 6 .

[0044] The structure of the solid oxide fuel cell 1 according to the first embodiment has been described above. In the above example, the structure of the cell unit of the solid oxide fuel cell 1 has been described, but the solid oxide fuel cell 1 may be provided as a cell module in which a plurality of cell units are stacked.

[0045] Next, a method for manufacturing the solid oxide fuel cell 1 according to the present embodiment will be described using an example. Figure 3 to Figure 7 1 is a schematic cross-sectional view showing the solid oxide fuel cell 1 during the manufacturing process.

[0046] (Step S1) Preparation of Green Sheet Laminate

[0047] First, if Figure 3As shown, a raw sheet stack 5' is prepared by stacking a raw sheet 3' for a first electrode structure, a raw sheet 2' for an electrolyte layer, and a raw sheet 4' for a second electrode structure. In addition, the raw sheet 3' for the first electrode structure has a raw sheet 3-2' for a first porous metal supporting layer and a raw sheet 3-1' for the first electrode layer. In addition, the raw sheet 4' for the second electrode structure has a raw sheet 4-2' for a second porous metal supporting layer and a raw sheet 4-1' for the second electrode layer. The raw sheet stack 5' can be formed, for example, by a tape casting method. Specifically, first, a slurry containing raw materials for each layer included in the stack is prepared. Then, each prepared slurry is formed in a sheet-like manner. Thus, the raw sheets of each layer can be obtained. And, the obtained raw sheets are stacked. Thus, a raw sheet stack 5' can be obtained.

[0048] (Step S2) Firing

[0049] Next, the green sheet laminate 5' is fired. Thus, a fired laminate in which the first porous metal supporting layer 3-2, the first electrode layer 3-1, the electrolyte layer 2, the second electrode layer 4-1, and the second porous metal supporting layer 4-2 are sequentially stacked can be obtained. In addition, at this time, the fired laminate has a symmetrical structure with the electrolyte layer 2 interposed therebetween, so that warping is unlikely to occur in the laminate 5 during firing.

[0050] (Step S3) Formation of Exposed Part

[0051] Next, if Figure 4 As shown, at least part of the second electrode structure 4 is removed from the outer periphery of the fired stack, so that the second electrode layer 4-1 or the electrolyte layer 2 is exposed. Thus, an exposed portion 12 is formed. The second electrode structure 4 can be chemically removed, for example, by etching using a solution (e.g., acid). Alternatively, the second electrode structure 4 can also be removed by mechanical processing. In the exposed portion 12 formed in this way, the surface roughness is coarser than the surface roughness of the surface of the second porous metal supporting layer 4-2. Therefore, when the seal 6 is formed in a later process, the seal 6 can be firmly bonded to the stack 5 by utilizing the anchoring effect.

[0052] (Step S4) Dam formation

[0053] Next, if Figure 5 As shown, the first dam 8 and the second dam 9 are formed on the first electrode structure 3. The first dam 8 and the second dam 9 can be formed by wire discharge machining and laser welding bead as described above. At this time, as described above, it is preferred that the first dam 8 is formed at a height that reaches the electrolyte layer 2. It is preferred that the second dam 9 is formed at a height that does not reach the electrolyte layer 2.

[0054] (Step S5) Formation of Filling Section

[0055] Next, if Figure 6 As shown, the filling material is supplied between the first dam 8 and the second dam 9 to form the filling portion 11. At this time, since the first dam 8 and the second dam 9 are provided, the filling material can be prevented from accidentally leaking outside the first dam 8 and inside the second dam 9.

[0056] When metal powder is used as a filler, for example, the metal powder is arranged at a predetermined position and melted by LMD (Laser Metal Deposition) to fill the pores with metal. When glass is used as a filler, the glass is melted by calcination to fill the pores with glass. When ceramics are used as a filler, for example, a liquid containing powdered ceramics is supplied between the first dam 8 and the second dam 9 and then fired to form the filling portion 11.

[0057] As described above, the filler is preferably supplied at a height that reaches the electrolyte layer 2 .

[0058] (Step S6) Joining the Metal Frame 7 and the Laminated Body 5

[0059] Next, if Figure 7 As shown, the laminate 5 is placed on the metal frame 7. Then, the filling portion 11 and the metal frame 7 are joined by welding. Thus, the welded portion 10 is formed, and the laminate 5 is fixed to the metal frame 7. The welded portion 10 can be formed by, for example, laser welding, brazing, or the like.

[0060] (Step S7) Formation of the seal 6

[0061] Next, the sealing member 6 is formed so as to cover the exposed portion 12 and the end of the laminate 5. Thus, a Figure 1 and Figure 2 In this case, as described above, the surface roughness becomes rougher at the exposed portion 12, so that the seal 6 and the stacked body 5 can be firmly bonded together by the anchor effect.

[0062] When glass is used as the seal 6, for example, glass powder is arranged at a predetermined position for forming the seal 6, and the glass powder is melted by heating to form the seal 6. Alternatively, a binder resin in which glass powder is dispersed is prepared, and the binder resin is applied to a predetermined position of the laminate 5 and fired to form the seal 6. Alternatively, a green sheet containing glass powder is arranged at a predetermined position and fired to form the seal 6.

[0063] According to the above method, in steps S1 and S2, the green sheet stack 5' is fired in batches. Then, the exposed portion 12, the first dam 8, the second dam 9, and the filling portion 11 are formed. According to such a method, it is not necessary to perform a firing process for forming each layer separately, and the firing process can be performed at one time, so the cost required for firing can be suppressed to a minimum.

[0064] In the above example, the following case is described: after the exposed portion 12 is formed in step S3, the dam and the filling portion 11 are formed in steps S4 to S5. However, the order is not limited. For example, the exposed portion 12 may be formed after the first dam 8, the second dam 9, and the filling portion 11 are formed.

[0065] The first embodiment has been described above. Hereinafter, representative structures and their effects in this embodiment will be summarized.

[0066] According to the present embodiment, the solid oxide fuel cell 1 comprises: a porous first electrode structure 3; an electrolyte layer 2 laminated on the first electrode structure 3; and a second electrode structure 4 laminated on the electrolyte layer 2. The first electrode structure 3 comprises: a first porous metal supporting layer 3-2; and a first electrode layer 3-1 provided between the first porous metal supporting layer 3-2 and the electrolyte layer 2. The first electrode structure 3 comprises: a filling portion 11, which is a region where pores are filled with a filling material and is provided in a ring-shaped manner when viewed along the stacking direction; and a first dam 8, which is located outside the filling portion 11 when viewed along the stacking direction and is a densified portion to prevent the filling material from leaking outside the filling portion 11. By adopting such a structure, even if the filling material in the filling portion 11 is softened at a high temperature, the softened filling material is intercepted by the first dam 8. Therefore, gas sealing can be maintained even at a high temperature and a high internal pressure.

[0067] In a preferred embodiment, the first electrode structure 3 is further provided with a second dam 9, which is provided inside the filling portion 11 when viewed along the stacking direction and is a portion that is densified to prevent the filling material from leaking inside the filling portion 11. By adopting such a structure, when the filling material is filled into the filling portion 11, the filling material is intercepted by the second dam 9, thereby preventing the filling material from accidentally leaking inside. In addition, it is also possible to prevent the softened filling material from leaking inside during operation.

[0068] In a preferred embodiment, the first dam 8 is set to a height that reaches the electrolyte layer 2 from the surface of the first electrode structure 3. In addition, the second dam 9 is set to a height lower than the height of the first dam 8 from the surface of the first electrode structure 3. According to such a structure, the first dam 8 is set at a height that reaches the electrolyte layer 2, so it is possible to more reliably prevent the filler from leaking to the outside. In addition, the second dam 9 does not reach the electrolyte layer 2, so the electrolyte layer 2 is not damaged. Therefore, it is possible to prevent the gas from leaking between the two electrodes through the damaged electrolyte layer 2.

[0069] In a preferred embodiment, a metal frame 7 is provided under the first electrode structure 3. The first electrode structure 3 is joined to the metal frame 7 at the filling portion 11. More preferably, the first electrode structure 3 is joined to the metal frame 7 by welding. By adopting such a structure, the first electrode structure 3 can be firmly joined to the metal frame 7, and the mechanical strength can be improved.

[0070] In a preferred embodiment, the filling portion 11 is formed to have a height from the surface of the first electrode structure 3 to the electrolyte layer 2. By adopting such a structure, leakage of the gas supplied to the first electrode structure 3 can be more reliably prevented.

[0071] In a preferred embodiment, the second electrode structure 4 includes: a second porous metal supporting layer 4-2; and a second electrode layer 4-1 provided between the second porous metal supporting layer 4-2 and the electrolyte layer 2. According to such a structure, the metal supporting layer is also provided on the second electrode structure 4 side, so that the structure of the stack 5 becomes a symmetrical structure centered on the electrolyte layer 2. By forming a symmetrical structure, the warping of the stack 5 when the green sheet stack 5' is fired can be reduced.

[0072] In a preferred embodiment, the solid oxide fuel cell 1 further includes a seal 6. An exposed portion 12 where the second electrode layer 4-1 or the electrolyte layer 2 is exposed is provided on the outer periphery of the second electrode structure 4. The seal 6 is provided so as to cover the end of the stack 5 and the exposed portion 12. According to such a structure, the seal 6 is bonded to the second electrode layer 4-1 or the electrolyte layer 2 at the exposed portion 12, so that the seal 6 can be firmly bonded to the end of the stack 5.

[0073] The manufacturing method of the solid oxide fuel cell 1 of the present embodiment comprises the following steps: a step of manufacturing a green sheet stack 5' in which a green sheet 3' for a first electrode structure, a green sheet 2' for an electrolyte layer, and a green sheet 4' for a second electrode structure are stacked; a step of firing the green sheet stack 5' to manufacture a fired stack; a step of forming a first dam 8 in a ring-shaped manner on the first electrode structure 3 when viewed along the stacking direction after the step of manufacturing the fired stack; and a step of supplying a filler to the first electrode structure 3 in a region on the inner side of the first dam 8 when viewed along the stacking direction to form a filling portion 11. According to such a method, it is sufficient to perform firing once when obtaining the stack 5. Therefore, the cost required for firing can be reduced.

[0074] In a preferred form, the manufacturing method of the present embodiment further comprises a step of forming a ring-shaped second dam 9 in a region located inside the first dam 8 when viewed along the stacking direction after the step of preparing the fired stacked body. The step of forming the filling portion 11 comprises a step of supplying a filling material between the first dam 8 and the second dam 9. According to this method, when the filling material is filled, the filling material is intercepted by the first dam 8 and the second dam 9. Therefore, it is possible to prevent the filling material from leaking to an unexpected region during manufacturing.

[0075] In a preferred embodiment, the second electrode structure 4 includes: a second porous metal supporting layer 4-2; and a second electrode layer 4-1, which is disposed between the second porous metal supporting layer 4-2 and the electrolyte layer 2. Furthermore, after the step of preparing the fired laminate, at least a portion of the second electrode structure 4 is removed from the outer periphery of the fired laminate so that the second electrode layer 4-1 or the electrolyte layer 2 is exposed to form an exposed portion 12. In addition, a seal 6 is formed in a manner covering the exposed portion 12 and the end of the fired laminate. According to this method, a rough surface exposed portion 12 can be formed by removing a portion of the outer portion of the second electrode structure 4 after firing. Furthermore, by bonding the seal 6 to the exposed portion 12, the seal 6 can be firmly bonded to the laminate 5 by utilizing an anchoring effect. Furthermore, the exposed portion 12 can be formed by processing the fired laminate after firing the green sheet laminate 5'. The exposed portion 12 can be formed by simple processing, so it is also advantageous in terms of manufacturing cost.

[0076] [Second embodiment]

[0077] Next, a second embodiment will be described. In this embodiment, a further improvement is made to the structure of the filling portion 11. In addition, in this embodiment, since the same structure as that of the first embodiment can be adopted, the description thereof will be omitted.

[0078] Figure 81 is a schematic cross-sectional view showing the end of the solid oxide fuel cell 1 of the present embodiment. In the present embodiment, the first electrode layer 3-1 is a porous ceramic layer. In addition, the pore size of the first electrode layer 3-1 is smaller than the pore size of the first porous metal supporting layer 3-2. In addition, the filling portion 11 is set to a height from the surface (lower surface) of the first electrode structure 3 to the electrolyte layer 2.

[0079] In the above-described structure, since two layers having different pore sizes exist in the first electrode structure 3 , it is difficult to uniformly fill the two layers with a filler. Therefore, in this embodiment, such a method is described below.

[0080] That is, in the present embodiment, the filling portion 11 includes a first filling portion 11 - 1 and a second filling portion 11 - 2 .

[0081] The first filling portion 11-1 is a region where the pores in the first electrode layer 3-1 are filled. The first filling portion 11-1 is filled with first particles as a filler. The first particles have a particle size smaller than the pore size of the first electrode layer 3-1. Ceramic particles such as cerium oxide are used as the first particles.

[0082] On the other hand, the second filling portion 11-2 is a region where the pores in the first porous metal supporting layer 3-2 are filled. The second filling portion 11-2 is filled with second particles as a filler. As the second particles, particles having a larger particle size than the first particles are used. However, the particle size of the second particles is smaller than the pore size of the first porous metal supporting layer 3-2.

[0083] As described above, in this embodiment, the first electrode layer 3-1 having a smaller pore size is filled with the first particles having a smaller particle size. Furthermore, the first porous metal supporting layer 3-2 having a larger pore size is filled with the second particles having a larger particle size. Since particles having a particle size corresponding to the pore size are filled as the filler, the filler can be densely filled in the entire filling portion 11.

[0084] Furthermore, a mixture of ceramic and metal (cermet) is filled as the second particles in the second filling portion 11-2. In addition, in the second filling portion 11-2, the ratio of ceramic to metal in the filling material is different in the height direction. Specifically, at a position close to the first electrode layer 3-1 (in the figure, region A), the ratio of ceramic to metal is large, and at a position close to the metal frame 7 (in the figure, region B), the ratio of ceramic is smaller than the ratio of ceramic in region A (the ratio of metal is larger than the ratio of metal in region A).

[0085] As described above, the first electrode layer 3-1 is formed of ceramic. In this embodiment, the ratio of ceramic increases at a position close to the first electrode layer 3-1, thereby improving the affinity between the second filling portion 11-2 and the first electrode layer 3-1. On the other hand, at a position close to the metal frame 7, the ratio of metal increases, thereby improving the affinity between the second filling portion 11-2 and the metal frame 7, and it is easy to form the welding portion 10.

[0086] Next, a method for manufacturing the solid oxide fuel cell 1 of the present embodiment will be described. The solid oxide fuel cell 1 of the present embodiment can be obtained by refining the process of forming the filling portion 11 (step S5) in the first embodiment.

[0087] Specifically, in the present embodiment, the first particles are filled into the pores of the first electrode layer 3-1 by pre-infiltrating the first electrode layer 3-1 with a liquid (slurry) containing the first particles as a filler. The filling of the first particles can be implemented at any stage as long as it is after the firing of the raw sheet stack (step S2). For example, after the firing of the raw sheet stack 5' and before the formation of the exposed portion 12, the liquid containing the first particles is supplied to the periphery of the first electrode structure 3. At this time, as the liquid containing the first particles, a liquid with a viscosity that can penetrate the first porous metal supporting layer 3-2 is used. Thus, the liquid containing the first particles penetrates the first porous metal supporting layer 3-2 and reaches the first electrode layer 3-1. Thereafter, a heat treatment is performed as needed, and the solvent is removed. Thus, the pores of the first electrode layer 3-1 can be filled with the first particles, and the first filling portion 11-1 can be formed in the first electrode layer 3-1.

[0088] Furthermore, after the first dam 8 and the second dam 8 are formed (after step S4), a mixture of metal and ceramic is filled between the first dam 8 and the second dam 9 as the second particles. For example, the second particles are supplied between the first dam 8 and the second dam 9 in a state where the second particles are dispersed in a binder or the like. After supplying, the binder or the like is removed by firing or the like as needed. At this time, first, a raw material having a larger ratio of ceramic to metal is supplied. Next, a raw material having a smaller ratio of ceramic to metal is filled. Thus, the second filling portion 11-2 can be formed in a manner in which the ratio of ceramic to metal is different in the height direction.

[0089] As described above, in the present embodiment, the filling portion 11 is set to a height from the surface of the first electrode structure 3 to the electrolyte layer 2. Moreover, the pore size in the first electrode layer 3-1 is smaller than the pore size in the first porous metal supporting layer 3-2. Furthermore, in the filling portion 11, the first electrode layer 3-1 is filled with the first particles as a filler, and the first porous metal supporting layer 3-2 is filled with the second particles having a larger particle size than the first particles as a filler. Since the particles having a particle size corresponding to the size of the pore size are filled, the filling material can be densely filled in the entire filling portion 11 even though the size of the pore size is different between the first electrode layer 3-1 and the first porous metal supporting layer 3-2.

[0090] In addition, according to the present embodiment, the first electrode layer 3-1 is a porous ceramic layer. In addition, in the filling portion 11, a mixture of ceramic and metal is filled in the first porous metal supporting layer 3-2 as a filling material. Moreover, the ratio of ceramic to metal in the filling material filled in the first porous metal supporting layer 3-2 is larger at a position close to the first electrode layer 3-1 and smaller at a position close to the metal frame 7. According to such a structure, the affinity between the second filling portion 11-2 and the first electrode layer 3-1 can be improved. In addition, the affinity between the metal frame 7 and the filling portion 11 can also be improved, and welding can be easily performed.

Claims

1. A solid oxide fuel cell comprising: A porous first electrode structure; an electrolyte layer stacked on the first electrode structure; and a second electrode structure, which is stacked on the electrolyte layer, The first electrode structure has: a first porous metal supporting layer; and a first electrode layer disposed between the first porous metal supporting layer and the electrolyte layer, The first electrode structure is provided with: A filling portion is a region where the pores are filled with a filler, and is provided in a ring shape when viewed along the stacking direction; and The first dam is located outside the filling portion when viewed along the stacking direction and is a portion densified to prevent the filling material from leaking outside the filling portion.

2. The solid oxide fuel cell according to claim 1, wherein: The first electrode structure further includes a second dam, which is provided inside the filling portion when viewed along the stacking direction and is a portion densified to prevent the filling material from leaking inside the filling portion.

3. The solid oxide fuel cell according to claim 2, wherein: The first dam is set to a height from the surface of the first electrode structure to the electrolyte layer. The second dam is set to have a height lower than that of the first dam from the surface of the first electrode structure.

4. The solid oxide fuel cell according to claim 1 or 2, wherein: The solid oxide fuel cell further comprises a metal frame disposed below the first electrode structure. The first electrode structure is joined to the metal frame at the filling portion.

5. The solid oxide fuel cell according to claim 4, wherein: The first electrode structure is joined to the metal frame by welding.

6. The solid oxide fuel cell according to claim 5, wherein: The first electrode layer is a porous ceramic layer. In the filling portion, the first porous metal supporting layer is filled with a mixture of ceramics and metal as the filling material. The ratio of ceramic to metal in the filler filled in the first porous metal supporting layer is larger at a position close to the first electrode layer and smaller at a position close to the metal frame.

7. The solid oxide fuel cell according to claim 1 or 2, wherein: The filling portion is set to a height reaching the electrolyte layer from the surface of the first electrode structure.

8. The solid oxide fuel cell according to claim 7, wherein: The pore size in the first electrode layer is smaller than the pore size in the first porous metal supporting layer. In the filling portion, the first electrode layer is filled with first particles as the filler, and the first porous metal supporting layer is filled with second particles having a larger particle size than the first particles as the filler.

9. The solid oxide fuel cell according to claim 1 or 2, wherein: The second electrode structure has: a second porous metal supporting layer; and The second electrode layer is provided between the second porous metal supporting layer and the electrolyte layer.

10. The solid oxide fuel cell according to claim 9, wherein: The solid oxide fuel cell further comprises a sealing member, An exposed portion where the second electrode layer or the electrolyte layer is exposed is provided on the outer periphery of the electrolyte layer on the second electrode structure side. The sealing member is provided so as to cover the end portion and the exposed portion of a stacked body composed of the first electrode structure, the electrolyte layer, and the second electrode structure.

11. A method for manufacturing the solid oxide fuel cell according to claim 1, wherein: The manufacturing method comprises the following steps: A step of manufacturing a green sheet stacked body in which the green sheet for the first electrode structure, the green sheet for the electrolyte layer, and the green sheet for the second electrode structure are stacked; The step of firing the green sheet stack to produce a fired stack consisting of the first electrode structure, the electrolyte layer, and the second electrode structure; After the step of manufacturing the fired laminate, a step of forming the first dam in the first electrode structure so as to be ring-shaped when viewed along the stacking direction; and A step of supplying the filling material to the first electrode structure to form the filling portion in a region on the inner side of the first dam when viewed along the stacking direction.

12. The manufacturing method according to claim 11, wherein: The manufacturing method further comprises: After the step of preparing the fired stacked body, a step of forming a second ring-shaped dam in a region located inside the first dam when viewed along the stacking direction, The step of forming the filling portion includes the step of supplying the filling material between the first dam and the second dam.

13. The manufacturing method according to claim 11, wherein: The second electrode structure has: a second porous metal supporting layer; and a second electrode layer provided between the second porous metal supporting layer and the electrolyte layer, The manufacturing method further comprises: After the step of preparing the fired laminate, a step of removing at least a portion of the second electrode structure at the outer periphery of the fired laminate to expose the second electrode layer or the electrolyte layer to form an exposed portion; A step of forming a sealing member in a manner covering the exposed portion and the end portion of the fired laminated body.

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