JP4902013B1 - Fuel cell - Google Patents

Abstract

[PROBLEMS] To provide a "horizontal stripe" capable of reforming a residual gas component before reforming which has flowed into a fuel gas flow path through a large number of pores inside a support substrate while ensuring insulation between adjacent fuel electrodes. Providing a “type” fuel cell.
A power generating element portion (a fuel electrode thereof) is disposed at a plurality of locations on a main surface of a flat porous support substrate 10 in which a gas flow path 11 is formed. The support substrate 10 exists in a portion close to the wall surface of the gas flow path 11 and includes a first portion 10a composed of a catalyst component and an electrically insulating component, and a support substrate 10 that is in contact with the fuel electrode of the power generation element portion A. And a second portion 10b that exists in a portion close to the main surface and is composed only of an electrically insulating component. In the gas flow path 11 of the support substrate 10, not only the gas after passing through the reformer that reforms the hydrocarbon gas (reformed gas (for example, hydrogen gas), but also before reforming). Including residual gas).
[Selection] Figure 1

Description

  The present invention relates to a fuel battery cell.

  Conventionally, "a porous support substrate having an insulating property in which a fuel gas flow path for flowing fuel gas is formed inside" and "a plurality of locations apart from each other on the outer surface of the support substrate" are provided. , A plurality of power generation element units in which at least a fuel electrode, a solid electrolyte, and an air electrode are stacked in this order ”and“ the one or more sets of adjacent power generation element units, respectively, There is known a fuel battery cell including one or a plurality of electrical connection portions that electrically connect one fuel electrode of the element portion and the other air electrode (see, for example, Patent Document 1). ). Such a configuration is also called a “horizontal stripe type”.

JP 2008-226789 A

  By the way, as the fuel gas (gas used for power generation reaction) introduced into the fuel gas flow path in the support substrate of the fuel cell, a hydrocarbon gas (for example, city) is usually used by using a reformer. A reformed gas (for example, hydrogen gas) obtained by reforming the gas) is used. However, the gas component that has not been reformed by the reformer (for example, city gas) is contained in the gas that has passed through the reformer (that is, gas introduced into the fuel gas flow path of the support substrate). ) May inevitably remain.

  The gas flowing into the fuel gas flow channel is supplied from the inner wall of the fuel gas flow channel to the fuel electrode through a large number of pores inside the porous support substrate, and used for power generation reaction. In order to increase the power generation efficiency of the fuel cell, it is preferable to supply as much reformed gas as possible to the fuel electrode. For this purpose, it is required to reform the residual gas component before reforming that has flowed into the fuel gas flow path in the process of passing through a large number of pores inside the support substrate.

  In order to achieve this requirement, it is conceivable to include a catalyst component (for example, nickel) that promotes the reforming reaction of the fuel gas in the material constituting the support substrate. In general, however, such catalyst components are electrically conductive. Therefore, if a large amount of the catalyst component is uniformly included in the material of the support substrate, it is difficult to ensure insulation of the support substrate.

  On the other hand, in the case of the “horizontal stripe type”, in order to prevent a short-circuit current from flowing between adjacent fuel electrodes, it is necessary to ensure the insulation of the support substrate. This is because, in the case of the “horizontal stripe type”, a plurality of fuel electrodes are provided at a plurality of locations separated from each other on the outer surface of the support substrate.

  As described above, in the “horizontal stripe type”, in the process of passing the residual gas component before reforming flowing into the fuel gas flow path through a large number of pores inside the support substrate while ensuring insulation between adjacent fuel electrodes. Therefore, it has been desired to be improved.

  The present invention has been made in order to solve the above-described problem. The remaining gas component before reforming that has flowed into the fuel gas passage is disposed inside the support substrate while ensuring insulation between adjacent fuel electrodes. An object is to provide a “horizontal stripe type” fuel cell that can be reformed in the process of passing through a large number of pores.

  The fuel battery cell according to the present invention includes a porous support substrate having insulating properties in which a fuel gas flow path for flowing fuel gas is formed, and a plurality of locations apart from each other on the outer surface of the support substrate. A plurality of power generation element portions, each of which is provided, and at least a fuel electrode, a solid electrolyte, and an air electrode are stacked in this order; and one set or a plurality of sets of the power generation element portions adjacent to each other. One or a plurality of electrical connection portions that electrically connect one fuel electrode and the other air electrode of the power generation element portion are provided. That is, this cell is a “horizontal stripe type” fuel cell.

A feature of the fuel battery cell according to the present invention is that a material constituting the support substrate includes a catalyst component that promotes a reforming reaction of a fuel gas and an electrically insulating component, and the fuel is contained inside the support substrate. The volume concentration of the catalyst component near the wall surface of the gas flow path is larger than the volume concentration of the catalyst component near the outer surface of the support substrate in contact with the fuel electrode. Here, the catalyst component is preferably conductive, but may be non-conductive. The catalyst component is, for example, a catalyst component that promotes a reforming reaction for reforming a hydrocarbon-based gas into hydrogen, and examples of the conductive component include Fe, Ni, Co, Cu, etc. Ni is preferred. Further, those having no conductivity, e.g., NiAl ₂ O ₄ and the like. NiAl ₂ O ₄ is described in detail, for example, in JP-A-2005-340164.

Hereinafter, additional remarks will be made regarding NiAl ₂ O ₄ . NiAl ₂ O ₄ is an oxidizing atmosphere (i.e., the supporting substrate inside the production stage or the like of cells functioning as an oxidizing atmosphere), the stably exist as NiAl ₂ O _4. This form shows insulation. However, NiAl ₂ O ₄ is present a reducing atmosphere (i.e., operation steps, such as the cell supporting substrate inside the reducing atmosphere) is better in, and the Ni and _Al 2 _{O 4} are present in isolation as NiAl ₂ O ₄ It becomes more stable than you do. Therefore, Ni precipitates from NiAl ₂ O ₄ . The deposited Ni functions as a “catalyst for promoting fuel gas reforming”. As described above, when NiAl ₂ O ₄ is uniformly included in the material of the support substrate as a catalyst component, it is difficult to ensure the insulating properties of the support substrate due to precipitation of conductive Ni during cell operation. That is, the same problem as in the case where Ni as a catalyst component is uniformly contained in the material of the support substrate may occur. As described above, as a material that exhibits “stable in an oxidizing atmosphere and decomposes in a reducing atmosphere to precipitate Ni” and can be used as the catalyst component, in addition to NiAl ₂ O ₄ , “NiO And MgO doped with “a spinel compound containing Ni” and the like.

  According to the above configuration, the volume concentration of the catalyst component in the “portion close to the wall surface of the fuel gas flow path” inside the porous support substrate can be increased. Therefore, the initial stage in the process in which the gas flowing into the fuel gas channel (including the residual gas component before reforming) is supplied from the fuel gas channel to the fuel electrode through a large number of pores inside the porous support substrate. In the stage, the reforming of the residual gas component before reforming is promoted by the catalytic action of the catalyst component. As a result, the residual gas component before reforming can be sufficiently reformed.

  In addition, according to the above configuration, the volume concentration of the catalyst component in the “portion close to the outer surface of the support substrate in contact with the fuel electrode” inside the porous support substrate can be reduced (for example, “0”). Accordingly, at least insulation of “a portion connecting adjacent fuel electrodes” inside the support substrate can be ensured. As a result, insulation can be ensured between adjacent fuel electrodes. As described above, according to the present invention, in the process in which the residual gas component before reforming that has flowed into the fuel gas flow path passes through a large number of pores inside the support substrate while ensuring insulation between adjacent fuel electrodes. It can be modified.

  In the fuel cell according to the present invention, specifically, for example, the support substrate is “a first portion including a wall surface of the fuel gas flow path (and not including an outer surface of the support substrate). A first portion composed of the electrically insulating component and the catalyst component, and “including the outer surface of the support substrate (and not including the wall surface of the fuel gas flow path) and the first portion. The second part connected to the part, and the second part composed of (only) the electrically insulating component ”. In this case, the volume concentration of the catalyst component in the first portion may be 5 to 50%. In addition, such a support substrate can be formed by integrating a molded body composed of a plurality of portions having different volume concentrations of the catalyst component by firing.

1 is a perspective view showing a fuel battery cell according to an embodiment of the present invention. It is sectional drawing corresponding to the 2-2 line of the fuel battery cell shown in FIG. It is a figure for demonstrating the operation state of the fuel battery cell shown in FIG. It is a figure for demonstrating the flow of the electric current in the operating state of the fuel battery cell shown in FIG. It is a perspective view which shows the 1st part of the support substrate shown in FIG. It is a perspective view which shows the whole containing the 1st, 2nd part of the support substrate shown in FIG. FIG. 3 is a cross-sectional view corresponding to FIG. 2 in a first stage in the manufacturing process of the fuel cell shown in FIG. 1. FIG. 3 is a cross-sectional view corresponding to FIG. 2 in a second stage in the manufacturing process of the fuel cell shown in FIG. 1. FIG. 3 is a cross-sectional view corresponding to FIG. 2 in a third stage in the manufacturing process of the fuel cell shown in FIG. 1. FIG. 4 is a cross-sectional view corresponding to FIG. 2 in a fourth stage in the manufacturing process of the fuel cell shown in FIG. 1. FIG. 6 is a cross-sectional view corresponding to FIG. 2 in a fifth stage in the manufacturing process of the fuel cell shown in FIG. 1. FIG. 6 is a cross-sectional view corresponding to FIG. 2 in a sixth stage in the manufacturing process of the fuel cell shown in FIG. 1. FIG. 8 is a cross-sectional view corresponding to FIG. 2 in a seventh stage in the manufacturing process of the fuel cell shown in FIG. 1. It is sectional drawing corresponding to FIG. 2 of the fuel cell concerning the other modification of embodiment of this invention. It is sectional drawing corresponding to FIG. 1 of the fuel cell concerning the other modification of embodiment of this invention. FIG. 7 is a perspective view corresponding to FIG. 6 of a fuel cell according to another modification of the embodiment of the present invention. FIG. 7 is a perspective view corresponding to FIG. 6 of a fuel cell according to another modification of the embodiment of the present invention. It is sectional drawing corresponding to FIG. 2 of the fuel cell which employ | adopted the support substrate shown in FIG. It is the top view which showed the state of the fuel electrode and interconnector which were embed | buried under the recessed part of the support substrate shown in FIG.

(Constitution)
FIG. 1 shows a solid oxide fuel cell (SOFC) cell according to an embodiment of the present invention. This SOFC cell has a plurality (four in this example) electrically connected in series to the upper and lower surfaces (main surfaces (planes) on both sides parallel to each other) of the flat support substrate 10 having a longitudinal direction. ) Having the same shape, the so-called “horizontal stripe type” is disposed at predetermined intervals in the longitudinal direction.

  The shape of the entire SOFC cell viewed from above is, for example, a rectangle having a side length of 5 to 50 cm in the longitudinal direction and a length of 1 to 10 cm in the width direction perpendicular to the longitudinal direction. The total thickness of this SOFC cell is 1-5 mm. The entire SOFC cell preferably has a vertically symmetrical shape with respect to a plane passing through the center in the thickness direction and parallel to the main surface of the support substrate 10, but is not limited thereto. Hereinafter, in addition to FIG. 1, the details of the SOFC cell will be described with reference to FIG. 2, which is a partial cross-sectional view of the SOFC cell corresponding to line 2-2 shown in FIG. FIG. 2 is a partial cross-sectional view showing a configuration (part of) each of a typical pair of adjacent power generation element portions A and A and a configuration between the power generation element portions A and A. The configuration between the other power generation element portions A and A in other sets is the same as the configuration shown in FIG.

  The support substrate 10 is a flat plate-like fired body having a longitudinal direction made of a porous material. The side end portion along the longitudinal direction of the support substrate 10 has a curved surface that is convex outward (in the width direction). A plurality (six in this example) of fuel gas passages 11 (through holes) extending in the longitudinal direction are formed in the support substrate 10 at predetermined intervals in the width direction.

The support substrate 10 is a first portion 10a (a region indicated by fine dots in FIGS. 1, 2 and other drawings) composed of an electrically insulating component (a component having no electronic conductivity) and a catalyst component. And a second portion 10b composed of an electrically insulating component (only). Examples of the electrical insulating component include CSZ (calcia stabilized zirconia), YSZ (8YSZ) (yttria stabilized zirconia), Y ₂ O ₃ (yttria), CaZrO ₃ (calcium zirconate), MgO (magnesia), MgAl ₂ O ₄ (spinel) or the like, or a mixture of any two or more thereof. Examples of the catalyst component include Ni (nickel) and Ru (ruthenium). The volume concentration of the catalyst component of the first portion 10a is 5 to 50%. The “volume concentration of the catalyst component” refers to the ratio of the volume of the catalyst component to the total volume excluding the pores.

  In this example, the first portion 10a is a single flat layer that includes the entirety of the plurality of fuel gas passages 11 therein. The first portion 10 a includes the inner wall surfaces of the plurality of fuel gas passages 11. The 2nd part 10b is a flat layer laminated | stacked on the upper and lower sides of the layer of the 1st part 10a, respectively. The outer surface of each second portion 10 b constitutes the outer surface (main surface) of the support substrate 10. That is, each second portion 10 b includes the outer surface of the support substrate 10. As will be described later, the fuel electrodes 20 of the plurality of power generating element portions A are in contact with the outer surface of each second portion 10b. The thickness of the support substrate 10 (distance between both main surfaces) is 1 to 5 mm. Hereinafter, only the configuration on the upper surface side of the support substrate 10 will be described for simplification of description. The same applies to the configuration of the lower surface side of the support substrate 10.

  As shown in FIG. 2, a rectangular parallelepiped fuel electrode 20 is provided on the upper surface (upper main surface) of the support substrate 10. The fuel electrode 20 is a fired body made of a porous material having electron conductivity. The fuel electrode 20 includes a fuel electrode active part 22 that contacts a solid electrolyte membrane 40 described later, and a fuel electrode current collector 21 that is the remaining part other than the fuel electrode active part 22. The shape of the anode active portion 22 viewed from above is a rectangle extending in the width direction over the range where the anode current collecting portion 21 exists.

The fuel electrode active part 22 can be composed of, for example, nickel oxide NiO and yttria stabilized zirconia YSZ (8YSZ). Alternatively, it may be composed of nickel oxide NiO and gadolinium-doped ceria GDC. The fuel electrode current collector 21 may be composed of, for example, nickel oxide NiO and yttria stabilized zirconia YSZ (8YSZ). Alternatively, it may be composed of nickel oxide NiO and yttria Y ₂ O ₃ , or may be composed of nickel oxide NiO and calcia stabilized zirconia CSZ. The thickness of the anode active portion 22 is 5 to 30 μm, and the thickness of the anode current collecting portion 21 is 50 to 500 μm.

  As described above, the fuel electrode current collector 21 includes a substance having electronic conductivity. The fuel electrode active part 22 includes a substance having electron conductivity and a substance having oxygen ion conductivity. The “volume ratio of the substance having oxygen ion conductivity with respect to the entire volume excluding the pore portion” in the anode active portion 22 is “having oxygen ion conductivity with respect to the entire volume excluding the pore portion” in the anode current collecting portion 21. It is larger than the “volume ratio of the substance”.

An interconnector 30 is formed at a predetermined location on the upper surface of each fuel electrode 20 (more specifically, each fuel electrode current collector 21). The interconnector 30 is a fired body made of a dense material having electronic conductivity. The shape of the interconnector 30 as viewed from above is a rectangle extending in the width direction over the range where the fuel electrode 20 exists. The interconnector 30 can be composed of, for example, LaCrO ₃ (lanthanum chromite). Alternatively, it may be composed of (Sr, La) TiO ₃ (strontium titanate). The thickness of the interconnector 30 is 10 to 100 μm.

The entire outer surface of the support substrate 10 in the state where the plurality of fuel electrodes 20 are provided, excluding the portion where the plurality of interconnectors 30 are formed, is covered with the solid electrolyte membrane 40. The solid electrolyte membrane 40 is a fired body made of a dense material having ionic conductivity and not electron conductivity. The solid electrolyte membrane 40 may be composed of, for example, YSZ (yttria stabilized zirconia) containing Y ₂ O ₃ (yttria). Or you may comprise from LSGM (lantern gallate). The thickness of the solid electrolyte membrane 40 is 3 to 50 μm.

  That is, the entire outer peripheral surface extending in the longitudinal direction of the support substrate 10 in a state where the plurality of fuel electrodes 20 are provided is covered with a dense layer composed of the interconnector 30 and the solid electrolyte membrane 40. This dense layer exhibits a gas sealing function that prevents mixing of the fuel gas flowing in the space inside the dense layer and the air flowing in the space outside the dense layer. Here, the “interconnector 30 and the solid electrolyte membrane 40” made of a dense material corresponds to the “gas seal portion”.

  An air electrode 60 is formed on the upper surface of a portion in contact with each fuel electrode active part 22 in the solid electrolyte membrane 40 via a reaction preventing film 50. The reaction preventing film 50 is a fired body made of a dense material, and the air electrode 60 is a fired body made of a porous material having electron conductivity and ion conductivity. The shape of the reaction preventing film 50 and the air electrode 60 viewed from above is substantially the same rectangle as the fuel electrode active part 22.

The reaction preventing film 50 can be made of, for example, GDC = (Ce, Gd) O ₂ (gadolinium-doped ceria). The thickness of the reaction preventing film 50 is 3 to 50 μm. The air electrode 60 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, from LSF = (La, Sr) FeO ₃ (lanthanum strontium ferrite), LNF = La (Ni, Fe) O ₃ (lanthanum nickel ferrite), LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite), etc. It may be configured. Further, the air electrode 60 may be configured by two layers of a first layer (inner layer) made of LSCF and a second layer (outer layer) made of LSC. The thickness of the air electrode 60 is 10 to 100 μm.

  The reaction preventing film 50 is interposed because the YSZ in the solid electrolyte film 40 and the Sr in the air electrode 60 react with each other in the SOFC during the production or operation of the SOFC, and the solid electrolyte film 40 and the air electrode. This is to suppress the occurrence of a phenomenon in which a reaction layer having a large electric resistance is formed at the interface with the film.

  Here, the laminated body formed by laminating the fuel electrode 20, the solid electrolyte membrane 40, the reaction preventing membrane 50, and the air electrode 60 corresponds to the “power generation element portion A” (see FIG. 2). In other words, a plurality (four in this example) of power generating element portions A are arranged on the upper surface of the support substrate 10 at a predetermined interval in the longitudinal direction.

  For each pair of adjacent power generation element portions A and A, the air electrode 60 of one power generation element portion A (on the left side in FIG. 2) and the interconnector of the other power generation element portion A (on the right side in FIG. 2). The air electrode current collecting film 70 is formed on the upper surfaces of the air electrode 60, the solid electrolyte film 40, and the interconnector 30. The air electrode current collector film 70 is a fired body made of a porous material having electron conductivity. The shape of the air electrode current collector film 70 as viewed from above is a rectangle.

The air electrode current collector film 70 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite) may be used. Or you may comprise from Ag (silver) and Ag-Pd (silver palladium alloy). The thickness of the air electrode current collector film 70 is 50 to 500 μm.

  By forming each air electrode current collecting film 70 in this way, for each pair of adjacent power generation element portions A and A, the air electrode 60 of one power generation element portion A (on the left side in FIG. 2), The other fuel electrode 20 (particularly, the fuel electrode current collector 21) of the power generating element part A (on the right side in FIG. 2) passes through the “air electrode current collector film 70 and interconnector 30” having electronic conductivity. Are electrically connected. As a result, a plurality (four in this example) of power generation element portions A arranged on the upper surface of the support substrate 10 are electrically connected in series. Here, the “air electrode current collector film 70 and the interconnector 30” having electronic conductivity correspond to “electrical connection portions”.

As described above, as shown in FIG. 3, the fuel gas flows into the fuel gas flow path 11 of the support substrate 10 and the upper and lower surfaces of the support substrate 10 (in particular, each of the above-described “horizontal stripe type” SOFC cells). The air electrode current collector film 70) is exposed to “a gas containing oxygen” (air or the like) (or a gas containing oxygen flows along the upper and lower surfaces of the support substrate 10). Thereby, an electromotive force is generated by an oxygen partial pressure difference generated between both side surfaces of the solid electrolyte membrane 40. Furthermore, when this structure is connected to an external load, chemical reactions shown in the following formulas (1) and (2) occur, and current flows (power generation state).
(1/2) · O ₂ + 2e ⁻ → O ²⁻ (where: air electrode 60) (1)
H ₂ + O ²⁻ → H ₂ O + 2e ⁻ (in the fuel electrode 20) (2)

  In the power generation state, as shown in FIG. 4, current flows as indicated by an arrow in each pair of adjacent power generation element portions A and A. As a result, as shown in FIG. 3, from the entire SOFC cell (specifically, in FIG. 3, the interconnector 30 of the power generating element portion A on the foremost side and the air electrode 60 of the power generating element portion A on the farthest side in FIG. The power is removed.

The fuel gas introduced into the fuel gas passage 11 is a reformed gas obtained by reforming a hydrocarbon-based gas (city gas CH ₄ or the like) using a reformer (not shown). (Hydrogen gas H ₂ or the like) is used. In the reformer, for example, the chemical reaction shown in the following formulas (3) and (4) occurs, so that the gas (CH ₄ ) before reforming becomes the gas (H ₂ ) used for the power generation reaction of SOFC. Reformed.

CH ₄ + H ₂ O → 3H ₂ + CO (3)
CO + H ₂ O → H ₂ + CO ₂ (4)

(Production method)
Next, an example of a manufacturing method of the “horizontal stripe type” SOFC cell shown in FIG. 1 will be briefly described with reference to FIGS. 5 to 13, “g” at the end of the reference numeral of each member indicates that the member is “before firing”.

  First, a molded body 10ag of the first portion of the support substrate having a thin plate shape shown in FIG. 5 is produced. This molded body 10ag can be produced, for example, by molding and solidifying the powder of the material (for example, CSZ and Ni) of the first portion 10a of the support substrate using a so-called extrusion molding method or the like.

  Next, as shown in FIG. 6, a molded body of the molded body 10 bg of the second portion of the support substrate is formed on the upper and lower surfaces of the molded body 10 ag obtained as described above. Thereby, 10 g of a molded body of the support substrate is obtained. The formed body 10bg can be formed by using a tape forming method, a printing method, or the like using a slurry obtained by adding a binder or the like to the powder of the material (for example, CSZ only) of the second portion 10b of the support substrate. . Hereinafter, the description will be continued with reference to FIGS. 7 to 13 showing a partial cross section of the molded body 10g of the support substrate shown in FIG.

  As shown in FIG. 7, when the support substrate molded body 10g is manufactured, next, as shown in FIG. 8, the upper and lower surfaces of the support substrate molded body 10g (more specifically, the second portion 10bg). A fuel electrode compact (21 g + 22 g) is formed at a predetermined position. The molded body (21 g + 22 g) of each fuel electrode is formed by using a printing method or the like using a slurry obtained by adding a binder or the like to the powder of the material of the fuel electrode 20 (for example, Ni and YSZ). The

Next, as shown in FIG. 9, an interconnector molded film 30g is formed at a predetermined location on the outer surface of the molded body 21g of each fuel electrode. The molded film 30g of each interconnector is formed by using a printing method or the like using a slurry obtained by adding a binder or the like to the powder of the material of the interconnector 30 (for example, LaCrO ₃ ).

  Next, as shown in FIG. 10, a plurality of interconnector molded bodies 30g are formed on the outer peripheral surface extending in the longitudinal direction of the molded body 10g of the support substrate in a state where a plurality of molded fuel electrode bodies (21g + 22g) are formed. A solid electrolyte membrane molded film 40g is formed on the entire surface (including the surface of the side end portion of the support substrate molded body 10g) excluding the formed portion. The molded membrane 40g of the solid electrolyte membrane is formed using, for example, a printing method, a dipping method, etc., using a slurry obtained by adding a binder or the like to the powder of the material of the solid electrolyte membrane 40 (for example, YSZ). The

  Next, as shown in FIG. 11, a molded film 50 g of the reaction preventing film is formed on the outer surface of the solid electrolyte membrane molded body 40 g in contact with the molded body 22 g of each fuel electrode. The molded film 50g of each reaction preventing film is formed using a slurry obtained by adding a binder or the like to the powder of the material (for example, GDC) of the reaction preventing film 50, using a printing method or the like.

  Then, 10 g of the support substrate molded body in which various molded films are formed in this way is fired in air at 1400 to 1500 ° C. for 1 to 20 hours. As a result, the structure in which the air electrode 60 and the air electrode current collector film 70 are not formed in the SOFC cell shown in FIG. 1 is obtained.

  Next, as shown in FIG. 12, an air electrode forming film 60 g is formed on the outer surface of each reaction preventing film 50. The molded film 60g of each air electrode is formed using a slurry obtained by adding a binder or the like to the powder of the material of the air electrode 60 (for example, LSCF), using a printing method or the like.

  Next, as shown in FIG. 13, for each pair of adjacent power generation element portions, air is formed so as to straddle the forming film 60 g of the air electrode of one power generation element portion and the interconnector 30 of the other power generation element portion. On the outer surface of the electrode forming film 60 g, the solid electrolyte film 40, and the interconnector 30, the air electrode current collecting film forming film 70 g is formed. The forming film 70g of each air electrode current collector film is obtained by using a slurry obtained by adding a binder or the like to the powder of the material of the air electrode current collector film 70 (for example, LSCF), using a printing method or the like. It is formed.

  And the support substrate 10 in the state in which the molded films 60g and 70g are formed in this way is fired at 900 to 1100 ° C. for 1 to 20 hours in the air. Thereby, the SOFC cell shown in FIG. 1 is obtained. The example of the method for manufacturing the SOFC cell shown in FIG. 1 has been described above.

(Give volume concentration distribution for catalyst components in the support substrate)
As described above, as a fuel gas (gas used for power generation reaction) introduced into the fuel gas flow path 11 in the support substrate 10 of the SOFC cell described above, carbonization is performed using a reformer (not shown). A reformed gas (for example, hydrogen gas H ₂ ) obtained by reforming a hydrogen-based gas (for example, city gas CH ₄ ) is used. However, in the gas that has passed through the reformer (that is, the gas introduced into the fuel gas flow path 11 of the support substrate 10), the gas component before reforming that could not be reformed by the reformer (for example, City gas CH ₄ ) can inevitably remain.

  The gas that has flowed into the fuel gas channel 11 is supplied from the inner wall of the fuel gas channel 11 to the fuel electrode 20 through a large number of pores inside the porous support substrate 10. Therefore, in order to increase the power generation efficiency of the SOFC, it is preferable to supply as much of the reformed gas as possible to the fuel electrode 20. For this purpose, it is required to reform the residual gas component before reforming that has flowed into the fuel gas flow path 11 in the process of passing through a large number of pores inside the support substrate 10.

  For this reason, it is conceivable that the material constituting the support substrate 10 includes a catalyst component (Ni or the like) that promotes the reforming reaction of the fuel gas (see the above formulas (3) and (4)). However, generally, the catalyst component (Ni or the like) has electrical conductivity. Therefore, if a large amount of the catalyst component is uniformly contained in the material of the support substrate 10, it is difficult to ensure insulation of the support substrate 10.

  On the other hand, in the case of a “horizontal stripe type” SOFC as in this example, at least “a portion connecting adjacent fuel electrodes” in the support substrate 10 in order to prevent a short-circuit current from flowing between adjacent fuel electrodes. It is necessary to ensure the insulation. This is due to the fact that in the case of a “horizontal stripe” SOFC, a plurality of fuel electrodes are provided at a plurality of locations separated from each other on the outer surface of the support substrate.

  In the SOFC cell according to the present embodiment, a volume concentration distribution is given to the catalyst component inside the support substrate 10 in consideration of the above-described contents. That is, the support substrate 10 is composed of a first portion 10a composed of an electrically insulating component (CSZ or the like) and a catalyst component (Ni or the like) and a second portion 10b composed only of the electrically insulating component. The Here, the first portion 10 a containing the catalyst component is present in the “portion close to the inner wall surface of the fuel gas passage 11” inside the support substrate 10. Therefore, the gas (including the residual gas component before reforming) flowing into the fuel gas channel 11 passes from the inner wall of the fuel gas channel 11 to the fuel electrode 20 through a number of pores inside the porous support substrate 10. In the initial stage of the supplied process, reforming of the residual gas component before reforming is promoted by the catalytic action of the catalyst component. As a result, the residual gas component before reforming can be sufficiently reformed.

  In addition, the second portion 10b that does not include a catalyst component (consisting only of an electrically insulating component) is the “portion close to the outer surface (main surface) of the support substrate 10 that contacts the fuel electrode 20” inside the support substrate 10. Exists. Therefore, insulation of at least “portion connecting adjacent fuel electrodes 20” inside the support substrate 10 can be ensured. As a result, insulation can be ensured between the adjacent fuel electrodes 20. As described above, according to the present embodiment, the remaining gas component before reforming that has flowed into the fuel gas flow path 11 has a large number of pores inside the support substrate 10 while ensuring insulation between the adjacent fuel electrodes 20. It can be modified in the process of passing. As a result, the power generation efficiency of the SOFC as a whole can be increased.

  In addition, this invention is not limited to the said embodiment, A various modification can be employ | adopted within the scope of the present invention. For example, in the above-described embodiment, the support substrate 10 includes the first portion 10a that includes a catalyst component and an electrical insulating component, and the second portion 10b that does not include a catalyst component and includes only an electrical insulating component. However, the first and second portions 10a and 10b are each composed of a catalyst component and an electrically insulating component, and the volume concentration of the catalyst component in the first portion 10a is greater than the volume concentration of the catalyst component in the second portion 10b. You may be comprised so that it may become large.

  In the above-described embodiment, the volume concentration of the “part close to the wall surface of the fuel gas channel 11” of the catalyst component inside the support substrate 10 is “the part close to the outer surface of the support substrate 10 in contact with the fuel electrode 20”. When the volume concentration distribution is given so as to be larger than the volume concentration, a two-stage distribution (5 to 50% in the first portion 10a and 0 to 20% in the second portion 10b) is given. The “volume concentration of the catalyst component” refers to the ratio of the volume of the catalyst component to the total volume excluding the pores. In contrast, the catalyst component in the support substrate 10 has a volume concentration from “a portion close to the wall surface of the fuel gas flow path 11” to “a portion close to the outer surface of the support substrate 10 in contact with the fuel electrode 20”. A volume concentration distribution may be given so as to gradually decrease. Furthermore, the support substrate may be configured by stacking two or more layers having different volume concentrations of the catalyst component. In this case, considering the complexity of the cell manufacturing process, the number of layers is preferably 10 or less.

  In the above embodiment, a plurality of power generation element portions A are provided on the upper and lower surfaces of the flat support substrate 10, but a plurality of power generation elements are provided only on one side of the support substrate 10 as shown in FIG. 14. The element part A may be provided. Further, in the above embodiment, the fuel electrode 20 is composed of two layers of the fuel electrode current collector 21 and the fuel electrode active portion 22, but the fuel electrode 20 is a single layer corresponding to the fuel electrode active portion 22. It may be configured.

  Moreover, in the said embodiment, the 1st part 10a which consists of a catalyst component and an electrical insulation component is a single flat layer which includes the whole of several fuel gas flow paths 11, and is electrically insulated. The 2nd part 10b which consists only of a component is a flat layer laminated | stacked on the upper and lower sides of the layer of the 1st part 10a, respectively. On the other hand, as shown in FIG. 15, the first portion 10a composed of the catalyst component and the electrically insulating component is a plurality of hollow cylindrical layers surrounding each of the fuel gas flow paths 11, The second portion 10b made of only the insulating component may be configured to be the remaining portion.

  The molded body of the second portion 10b of the support substrate shown in FIG. 15 is formed by, for example, molding and solidifying the powder of the material (for example, CSZ) of the second portion 10b of the support substrate using a so-called extrusion molding method or the like. Can be made. For example, the molded body of the first portion 10a of the support substrate shown in FIG. 15 is formed on the inner wall of the hole corresponding to the fuel gas flow path 11 in the molded body of the second portion 10b using the dip coating method. It can be produced by forming a film made of the material of the first portion 10a (for example, CSZ and Ni). Furthermore, after the molded body of the second portion 10b is fired, the first portion 10a may be provided using a dip coating method for the hole corresponding to the fuel gas flow path 11 in the fired body.

  Also in the embodiment shown in FIG. 15, the first and second portions 10a and 10b are each composed of a catalyst component and an electrically insulating component, and the volume concentration of the catalyst component in the first portion 10a is that of the second portion 10b. You may be comprised so that it may become larger than the volume concentration of a catalyst component.

In addition, in the embodiment, Ni having conductivity as a catalyst component is used, NiAl ₂ O ₄ may be used as a catalyst component. NiAl ₂ O ₄ is stably present in an oxidizing atmosphere and exhibits insulating properties. However, in the operation stage of the cell (that is, the stage in which the inside of the support substrate becomes a reducing atmosphere), Ni and Al ₂ O ₄ are separated and exist more stably than NiAl ₂ O _4. Then, Ni precipitates from NiAl ₂ O ₄ . The deposited Ni functions as a “catalyst for promoting fuel gas reforming”. As described above, the material that is stable in an oxidizing atmosphere and decomposes in a reducing atmosphere to precipitate Ni and that can be used as a catalyst component includes, in addition to NiAl ₂ O ₄ , “NiO “Doped MgO”, “spinel compound containing Ni” and the like.

  Further, in the above embodiment, the fuel electrode 20 is formed (laminated) on the outer surface (planar) of the flat support substrate 10 and the interconnector 30 is formed on the outer surface (plane) of the fuel electrode 20 ( 16-19, the fuel electrode 20 is embedded in a recess (see FIGS. 16 and 17) formed on the outer surface of the support substrate 10, and the interconnector 30 is a fuel. It may be embedded in a recess formed on the outer surface of the pole 20. Hereinafter, the main differences of the form shown in FIGS. 16 to 19 with respect to the above embodiment will be briefly described.

  In the form shown in FIGS. 16 to 19, a plurality of recesses 12 are formed on the main surface (upper and lower surfaces) of the support substrate 10 at predetermined intervals in the longitudinal direction. Each recess 12 has a bottom wall made of the material of the support substrate 10 and side walls closed in the circumferential direction made of the material of the support substrate 10 (two side walls along the longitudinal direction and two side walls along the width direction). ) And a rectangular parallelepiped depression defined by The entire fuel electrode current collector 21 is embedded (filled) in each recess 12. Therefore, each fuel electrode current collector 21 has a rectangular parallelepiped shape.

  A recess 21 a is formed on the upper surface (outer surface) of each fuel electrode current collector 21. Each recess 21a has a rectangular parallelepiped shape defined by a bottom wall made of the material of the fuel electrode current collector 21 and side walls closed in the circumferential direction (two side walls along the longitudinal direction and two side walls along the width direction). It is a depression. Of the side walls closed in the circumferential direction, two side walls along the longitudinal direction are made of the material of the support substrate 10, and two side walls along the width direction are made of the material of the fuel electrode current collector 21.

  The entire anode active portion 22 is embedded (filled) in each recess 21a. Accordingly, each fuel electrode active portion 22 has a rectangular parallelepiped shape. A fuel electrode 20 is configured by the fuel electrode current collector 21 and the fuel electrode active unit 22. The fuel electrode 20 (fuel electrode current collector 21 + fuel electrode active part 22) is a fired body made of a porous material having electron conductivity. The two side surfaces and the bottom surface along the width direction of each anode active portion 22 are in contact with the anode current collecting portion 21 in the recess 21a.

  A recess 21b is formed in a portion of the upper surface (outer surface) of each fuel electrode current collector 21 excluding the recess 21a. Each recess 21b includes a bottom wall made of a material of the fuel electrode current collector 21 and a circumferentially closed side wall made of the material of the fuel electrode current collector 21 (two side walls along the longitudinal direction). And two side walls along the width direction).

  An interconnector 30 is embedded (filled) in each recess 21b. Accordingly, each interconnector 30 has a rectangular parallelepiped shape. The interconnector 30 is a fired body made of a dense material having electronic conductivity. The four side walls (two side walls along the longitudinal direction and two side walls along the width direction) and the bottom surface of each interconnector 30 are in contact with the fuel electrode current collector 21 in the recess 21b.

  The upper surface (outer surface) of the fuel electrode 20 (the fuel electrode current collector 21 and the fuel electrode active unit 22), the upper surface (outer surface) of the interconnector 30, and the main surface of the support substrate 10 form one plane (recessed portion). The same plane as the main surface of the support substrate 10 when 12 is not formed) is formed. That is, no step is formed between the upper surface of the fuel electrode 20, the upper surface of the interconnector 30, and the main surface of the support substrate 10.

The fuel electrode active part 22 may be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Or you may comprise from NiO (nickel oxide) and GDC (gadolinium dope ceria). The fuel electrode current collector 21 can be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Alternatively, it may be composed of NiO (nickel oxide) and Y ₂ O ₃ (yttria), or may be composed of NiO (nickel oxide) and CSZ (calcia stabilized zirconia). The thickness of the anode active portion 22 is 5 to 30 μm, and the thickness of the anode current collecting portion 21 (that is, the depth of the recess 12) is 50 to 500 μm.

  As described above, the fuel electrode current collector 21 includes a substance having electronic conductivity. The fuel electrode active part 22 includes a substance having electron conductivity and a substance having oxygen ion conductivity. The “volume ratio of the substance having oxygen ion conductivity with respect to the entire volume excluding the pore portion” in the anode active portion 22 is “having oxygen ion conductivity with respect to the entire volume excluding the pore portion” in the anode current collecting portion 21. It is larger than the “volume ratio of the substance”.

The interconnector 30 can be composed of, for example, LaCrO ₃ (lanthanum chromite). Alternatively, it may be composed of (Sr, La) TiO ₃ (strontium titanate). The thickness of the interconnector 30 is 10 to 100 μm.

  The entire surface excluding the central portion in the longitudinal direction of each portion where the plurality of interconnectors 30 are formed on the outer peripheral surface extending in the longitudinal direction of the support substrate 10 in a state where the fuel electrode 20 and the interconnector 30 are embedded in the respective recesses 12. Is covered with a solid electrolyte membrane 40. The solid electrolyte membrane 40 is a fired body made of a dense material having ionic conductivity and not electron conductivity. The solid electrolyte membrane 40 can be made of, for example, YSZ (8YSZ) (yttria stabilized zirconia). Or you may comprise from LSGM (lantern gallate). The thickness of the solid electrolyte membrane 40 is 3 to 50 μm.

  That is, the entire outer peripheral surface extending in the longitudinal direction of the support substrate 10 in a state where the fuel electrode 20 is embedded in each recess 12 is covered with a dense layer composed of the interconnector 30 and the solid electrolyte membrane 40. This dense layer exhibits a gas sealing function that prevents mixing of the fuel gas flowing in the space inside the dense layer and the air flowing in the space outside the dense layer.

  As shown in FIG. 18, in this example, the solid electrolyte membrane 40 covers the upper surface of the fuel electrode 20, both side ends in the longitudinal direction on the upper surface of the interconnector 30, and the main surface of the support substrate 10. Here, as described above, no step is formed between the upper surface of the fuel electrode 20, the upper surface of the interconnector 30, and the main surface of the support substrate 10. Therefore, the solid electrolyte membrane 40 is flattened. As a result, compared with the case where a step is formed in the solid electrolyte membrane 40, the generation of cracks in the solid electrolyte membrane 40 due to stress concentration can be suppressed, and the gas sealing function of the solid electrolyte membrane 40 is reduced. Can be suppressed.

  An air electrode 60 is formed on the upper surface of a portion in contact with each fuel electrode active part 22 in the solid electrolyte membrane 40 via a reaction preventing film 50. The reaction preventing film 50 is a fired body made of a dense material, and the air electrode 60 is a fired body made of a porous material having electron conductivity. The shape of the reaction preventing film 50 and the air electrode 60 viewed from above is substantially the same rectangle as the fuel electrode active part 22.

The reaction preventing film 50 can be made of, for example, GDC = (Ce, Gd) O ₂ (gadolinium-doped ceria). The thickness of the reaction preventing film 50 is 3 to 50 μm. The air electrode 60 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, from LSF = (La, Sr) FeO ₃ (lanthanum strontium ferrite), LNF = La (Ni, Fe) O ₃ (lanthanum nickel ferrite), LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite), etc. It may be configured. Further, the air electrode 60 may be configured by two layers of a first layer (inner layer) made of LSCF and a second layer (outer layer) made of LSC. The thickness of the air electrode 60 is 10 to 100 μm.

  The reaction preventing film 50 is interposed because the YSZ in the solid electrolyte film 40 and the Sr in the air electrode 60 react with each other in the SOFC during the production or operation of the SOFC, and the solid electrolyte film 40 and the air electrode. This is to suppress the occurrence of a phenomenon in which a reaction layer having a large electric resistance is formed at the interface with the film.

  Here, the laminated body formed by laminating the fuel electrode 20, the solid electrolyte membrane 40, the reaction preventing membrane 50, and the air electrode 60 corresponds to the “power generation element portion A” (see FIG. 18). In other words, a plurality (four in this example) of power generating element portions A are arranged on the upper surface of the support substrate 10 at a predetermined interval in the longitudinal direction.

  For each pair of adjacent power generation element portions A and A, the air electrode 60 of one power generation element portion A (on the left side in FIG. 18) and the interconnector of the other power generation element portion A (on the right side in FIG. 18). The air electrode current collecting film 70 is formed on the upper surfaces of the air electrode 60, the solid electrolyte film 40, and the interconnector 30. The air electrode current collector film 70 is a fired body made of a porous material having electron conductivity. The shape of the air electrode current collector film 70 as viewed from above is a rectangle.

The air electrode current collector film 70 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite) may be used. Or you may comprise from Ag (silver) and Ag-Pd (silver palladium alloy). The thickness of the air electrode current collector film 70 is 50 to 500 μm.

  By forming each air electrode current collecting film 70 in this way, for each pair of adjacent power generation element parts A and A, the air electrode 60 of one power generation element part A (on the left side in FIG. 18), The other fuel electrode 20 (particularly, the fuel electrode current collector 21) of the power generating element part A (on the right side in FIG. 18) passes through the “air electrode current collector film 70 and interconnector 30” having electronic conductivity. Are electrically connected. As a result, a plurality (four in this example) of power generation element portions A arranged on the upper surface of the support substrate 10 are electrically connected in series. Here, the “air electrode current collector film 70 and the interconnector 30” having electronic conductivity correspond to the “electrical connection part”.

  The interconnector 30 corresponds to the “first portion made of a dense material” in the “electrical connection portion” and has a porosity of 10% or less. The air electrode current collecting film 70 corresponds to the “second portion made of a porous material” in the “electrical connection portion”, and has a porosity of 20 to 60%.

  As described above, in the embodiments shown in FIGS. 16 to 19, as in the above embodiment, the support substrate 10 includes the first portion 10 a composed of the electrically insulating component (CSZ or the like) and the catalyst component (Ni or the like), and the electric The second portion 10b is composed of only a mechanical insulating component (see FIGS. 16 and 17). As a result, insulation can be ensured between the adjacent fuel electrodes 20. Therefore, as in the above-described embodiment, the remaining gas component before reforming that has flowed into the fuel gas flow path 11 passes through a large number of pores inside the support substrate 10 while ensuring insulation between the adjacent fuel electrodes 20. It can be modified in the process. As a result, the power generation efficiency of the SOFC as a whole can be increased.

  Further, each of the plurality of recesses 12 for embedding the fuel electrode 20 has a side wall closed in the circumferential direction made of the material of the support substrate 10 over the entire circumference. In other words, the support body 10 is formed with a frame surrounding each recess 12. Therefore, this structure is not easily deformed when the support substrate 10 receives an external force.

  Further, the support substrate 10 and the embedded member are co-sintered in a state in which the members such as the fuel electrode 20 and the interconnector 30 are filled and embedded in the recesses 12 of the support substrate 10 without any gap. Therefore, a sintered body having high bondability between members and high reliability can be obtained.

  Further, the interconnector 30 is embedded in a recess 21b formed on the outer surface of the fuel electrode current collector 21, and as a result, the four sidewalls of the rectangular parallelepiped interconnector 30 (two sidewalls along the longitudinal direction, width) Two side walls along the direction) and the bottom face are in contact with the anode current collector 21 in the recess 21b. Therefore, the fuel electrode 20 (the current collector 21) and the interconnector 30 are compared to the case where a configuration in which the rectangular parallelepiped interconnector 30 is laminated (contacted) on the outer plane of the fuel electrode current collector 21 is employed. The area of the interface with can be increased. Therefore, the electronic conductivity between the fuel electrode 20 and the interconnector 30 can be increased, and as a result, the power generation output of the fuel cell can be increased.

  A plurality of power generating element portions A are provided on the upper and lower surfaces of the flat support substrate 10. Thereby, compared with the case where a plurality of power generation element portions are provided only on one side surface of the support substrate, the number of power generation element portions in the structure can be increased, and the power generation output of the fuel cell can be increased.

  In addition, the solid electrolyte membrane 40 covers the outer surface of the fuel electrode 20, both longitudinal ends of the outer surface of the interconnector 30, and the main surface of the support substrate 10. Here, no step is formed between the outer surface of the fuel electrode 20, the outer surface of the interconnector 30, and the main surface of the support substrate 10. Therefore, the solid electrolyte membrane 40 is flattened. As a result, compared with the case where a step is formed in the solid electrolyte membrane 40, the generation of cracks in the solid electrolyte membrane 40 due to stress concentration can be suppressed, and the gas sealing function of the solid electrolyte membrane 40 is reduced. Can be suppressed.

  DESCRIPTION OF SYMBOLS 10 ... Support substrate, 10a ... 1st part, 10b ... 2nd part, 11 ... Fuel gas flow path, 12 ... Recessed part, 20 ... Fuel electrode, 21 ... Fuel electrode current collection part, 21b ... Recessed part, 22 ... Fuel electrode active , 30 ... interconnector, 40 ... solid electrolyte membrane, 50 ... reaction prevention membrane, 60 ... air electrode, 70 ... air electrode current collector membrane, 80 ... insulator, A ... power generation element portion

Claims (8)

A porous support substrate having a fuel gas passage for flowing fuel gas formed therein;
A plurality of power generating element portions each provided at a plurality of locations apart from each other on the outer surface of the support substrate, wherein at least a fuel electrode, a solid electrolyte, and an air electrode are stacked in this order;
One or a plurality of electrical connections that are respectively provided between one or a plurality of adjacent power generation element portions and electrically connect one fuel electrode and the other air electrode of the adjacent power generation element portions. And
In a fuel cell comprising:
The material constituting the support substrate includes a catalyst component that promotes a reforming reaction of fuel gas and an electrically insulating component, and the catalyst in a portion near the wall surface of the fuel gas flow path inside the support substrate The fuel cell, wherein the volume concentration of the component is larger than the volume concentration of the catalyst component in a portion close to the outer surface of the support substrate in contact with the fuel electrode. The fuel cell according to claim 1,
The support substrate is
A first portion including a wall surface of the fuel gas flow path, the first portion including the electrically insulating component and the catalyst component;
A second part including the outer surface of the support substrate and connected to the first part, the second part comprising the electrically insulating component;
A fuel cell comprising: The fuel cell according to claim 2,
The fuel cell, wherein the volume concentration of the catalyst component in the first portion is 5 to 50%. In the fuel cell according to any one of claims 1 to 3,
The fuel cell, wherein the catalyst component is a catalyst component that promotes a reforming reaction for reforming a hydrocarbon-based gas into hydrogen. The fuel cell according to claim 4, wherein
The fuel battery cell, wherein the catalyst component is nickel. In the fuel cell according to any one of claims 1 to 5,
The support substrate is
A fuel battery cell, in which formed bodies composed of a plurality of portions having different volume concentrations of the catalyst component are integrated by firing. A flat porous support substrate having a fuel gas flow path formed therein for flowing a fuel gas;
A plurality of power generating element portions each provided at a plurality of positions separated from each other on the outer surface of the flat support substrate, and at least a fuel electrode, a solid electrolyte, and an air electrode are laminated in this order;
One or a plurality of electrical connections that are respectively provided between one or a plurality of adjacent power generation element portions and electrically connect one fuel electrode and the other air electrode of the adjacent power generation element portions. And
In a fuel cell comprising:
Recesses having a bottom wall made of the material of the support substrate and a side wall closed in the circumferential direction made of the material of the support substrate over the entire circumference at the plurality of locations on the outer surface of the flat support substrate, respectively. Formed,
In each of the recesses, the corresponding fuel electrode of the power generation element portion is embedded,
The material constituting the support substrate includes a catalyst component that promotes a reforming reaction of fuel gas and an electrically insulating component, and the catalyst in a portion near the wall surface of the fuel gas flow path inside the support substrate The fuel cell, wherein the volume concentration of the component is larger than the volume concentration of the catalyst component in a portion close to the outer surface of the support substrate in contact with the fuel electrode. A flat porous support substrate having a fuel gas flow path formed therein for flowing a fuel gas;
A plurality of power generating element portions each provided at a plurality of positions separated from each other on the outer surface of the flat support substrate, and at least a fuel electrode, a solid electrolyte, and an air electrode are laminated in this order;
One or a plurality of electrical connections that are respectively provided between one or a plurality of adjacent power generation element portions and electrically connect one fuel electrode and the other air electrode of the adjacent power generation element portions. And
In a fuel cell comprising:
Each of the electrical connection portions includes a first portion made of a dense material, and a second portion made of a porous material connected to the first portion,
A first recess having a bottom wall made of the material of the support substrate and a side wall made of the material of the support substrate in the circumferential direction at the plurality of locations on the outer surface of the flat support substrate. Each formed,
In each of the first recesses, the corresponding fuel electrode of the power generation element unit is embedded,
Second recesses each having a bottom wall made of the fuel electrode material and a circumferentially closed side wall made of the fuel electrode material are formed on the outer surface of each buried fuel electrode. ,
In each of the second recesses, the corresponding first portion of the electrical connection portion is embedded,
The material constituting the support substrate includes a catalyst component that promotes a reforming reaction of fuel gas and an electrically insulating component, and the catalyst in a portion near the wall surface of the fuel gas flow path inside the support substrate The fuel cell, wherein the volume concentration of the component is larger than the volume concentration of the catalyst component in a portion close to the outer surface of the support substrate in contact with the fuel electrode.

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