JP2015076339A - Fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery whose inner electrode embedded in a concave portion formed in a principal plane of a support substrate with a gas passage formed therein, and having a large joining strength at "an interface of a second seal part, which is part of a gas-seal part, and a fuel electrode".SOLUTION: In a fuel battery, a gas-seal part includes: a dense solid electrolyte 40 forming part of a power generation element part A; a first seal part 40 connected with the solid electrolyte 40, and made of a dense constituent material which is the same as or different from that of the solid electrolyte 40; a second seal part 35 connected with the first seal part 40, and made of a dense constituent material different from that of the first seal part 40; and an interconnector 30 connected with the second seal part 35. In a cross section including the second seal part 35 made of the dense material and a fuel electrode current collecting part 21 made of a porous material after a reduction treatment, the "joining rate" is 36-78%, and the "joining width" is 0.3-3.3 μm.

Description

  The present invention relates to a fuel cell.

  Conventionally, “a support substrate having a gas flow path formed therein” and “provided respectively at a plurality of locations apart from each other on the main surface of the support substrate, and at least a fuel electrode, a solid electrolyte, and an air electrode are stacked. A plurality of power generation element portions ”and“ one set of or a plurality of sets of adjacent power generation element portions, and electrically connecting one fuel electrode and the other air electrode of the adjacent power generation element portions ”. One or a plurality of electrical connecting portions connected to the first electrode and the air electrode provided between the one or a plurality of adjacent power generation element portions and supplied to the fuel electrode, respectively. There is known a fuel cell including a gas seal portion made of a dense constituent material that prevents mixing with the second gas supplied to the gas (see, for example, Patent Document 1). Such a configuration is also called a “horizontal stripe type”.

  In the fuel cell described in this document, first recesses each having a bottom wall made of the material of the support substrate and a side wall made of the material of the support substrate at the plurality of locations on the main surface of the support substrate, respectively. Is formed. The fuel electrode of the corresponding power generation element portion is embedded in each first recess. Each of the electrical connection portions includes a first portion (interconnector) made of a dense material, and a second portion (air electrode current collector membrane) connected to the first portion and made of a porous material. The first portion is connected to one fuel electrode of the adjacent power generation element portion and the second portion, and the second portion is connected to the other air electrode of the adjacent power generation element portion. Connected to the first portion.

Japanese Patent No. 4824135

  By the way, in the fuel cell having the above-described configuration, it is required to reliably suppress the deterioration of the gas seal function of the gas seal portion. For this reason, this inventor has already proposed the following structure about the said gas seal part in Japanese Patent Application No. 2013-122592. That is, in the portion covering the outer surface of each buried fuel electrode in the gas seal portion, the gas seal portion is connected to the dense solid electrolyte as a part of the power generation element portion and the solid electrolyte. And a first seal portion made of a dense constituent material that is the same as or different from the solid electrolyte, and a second seal portion made of a dense constituent material that is connected to the first seal portion and is different from the first seal portion. And a first part of the electrical connection part connected to the second seal part, wherein the first seal part and the first part of the electrical connection part are configured not to contact each other.

  In the gas seal part, the second seal part is made of a dense material, and the fuel electrode is made of a porous material. Therefore, the interface between the second seal portion and the fuel electrode is a boundary between the dense layer and the porous layer.

  In this way, the inventor has paid attention to the “interface between the second seal portion and the fuel electrode” which is a boundary between the dense layer and the porous layer. And this inventor discovered the conditions which joining strength becomes large regarding the joining state (contact state) of this interface.

  That is, the present invention relates to a fuel cell in which an inner electrode is embedded in a recess formed in a main surface of a support substrate in which a gas flow path is formed, and “a second seal that is a part of a gas seal portion”. An object of the present invention is to provide a high bonding strength with respect to the bonding state of the “interface between the fuel cell and the fuel electrode”.

  The gas seal part of the fuel cell according to the present invention is connected to the dense solid electrolyte as a part of the power generation element part and the dense electrolyte that is the same as or different from the solid electrolyte and connected to the solid electrolyte, as described above. The first seal part made of a constituent material, the second seal part made of a dense constituent material that is connected to the first seal part and different from the first seal part, and the second seal part connected to the second seal part And a first portion of the electrical connection portion.

  The fuel cell according to the present invention is characterized in that, in a state where the fuel cell is a reductant that has been heat-treated in a reducing atmosphere, “the second seal portion in a cross section including the second seal portion and the fuel electrode” For "the length of the boundary line corresponding to the interface with the fuel electrode", "the total length of the plurality of portions where the second seal portion and the fuel electrode are in contact with each other on the boundary line" The “joining rate” as a ratio is 36 to 78%.

  As will be described later, the present inventor found that when the “joining rate” is 36 to 78%, compared with the case where the “joining rate” is not 36 to 78%, “the second seal portion and the fuel electrode It has been found that the bonding strength increases at the “interface”.

  In addition, as will be described later, in the state where the fuel cell is a reductant that has been heat-treated in a reducing atmosphere and the “joining rate” is 36 to 78%, When the “joining width”, which is the average of the lengths of the plurality of portions in contact with the second seal portion and the fuel electrode, is 0.3 to 3.3 μm, the joining strength may be particularly increased. I found it.

1 is a perspective view showing a fuel cell according to the present invention. FIG. 2 is a cross-sectional view corresponding to line 2-2 of the fuel cell shown in FIG. It is the top view which showed the state of the fuel electrode, the interconnector, and the sealing material which were embed | buried under the recessed part formed on the main surface of the support substrate shown in FIG. It is a figure corresponding to FIG. 3 in the state in which the solid electrolyte membrane was formed on the main surface of a support substrate. It is a figure for demonstrating the operation state of the fuel cell shown in FIG. It is a figure for demonstrating the flow of the electric current in the operating state of the fuel cell shown in FIG. It is a perspective view which shows 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. 7 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. FIG. 7 is a cross-sectional view corresponding to FIG. 2 in an eighth stage in the manufacturing process of the fuel cell shown in FIG. 1. FIG. 10 is a cross-sectional view corresponding to FIG. 2 in a ninth stage in the manufacturing process of the fuel cell shown in FIG. 1. FIG. 2 is a schematic diagram showing a “structure around a recess formed in an outer surface of a fuel electrode” in the fuel cell shown in FIG. 1. It is the schematic diagram which showed the "structure around the recessed part formed in the outer surface of a fuel electrode" in the conventional fuel cell. It is sectional drawing corresponding to FIG. 17 of the 1st modification of the fuel cell which concerns on this invention. It is sectional drawing corresponding to FIG. 17 of the 2nd modification of the fuel cell which concerns on this invention. It is sectional drawing corresponding to FIG. 17 of the 3rd modification of the fuel cell which concerns on this invention. It is sectional drawing corresponding to FIG. 17 of the 4th modification of the fuel cell which concerns on this invention. It is sectional drawing corresponding to FIG. 17 of the 5th modification of the fuel cell which concerns on this invention. It is sectional drawing corresponding to FIG. 17 of the 6th modification of the fuel cell which concerns on this invention. FIG. 5 is a sketch diagram of an image obtained by enlarging a cross section including a seal portion and a fuel electrode current collector according to an embodiment of the present invention with an electron microscope, for explaining “joining rate” and “joining width”; FIG. It is sectional drawing corresponding to FIG. 2 of the 7th modification of the fuel cell which concerns on this invention.

(Constitution)
FIG. 1 shows a structure of a solid oxide fuel cell (SOFC) according to an embodiment of the present invention. This SOFC structure is 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 (x-axis direction). (In this example, four) power generation element portions A having the same shape are arranged at a predetermined interval in the longitudinal direction and have a so-called “horizontal stripe type” configuration.

  The shape of the entire SOFC structure as viewed from above is, for example, a rectangle having a length of 50 to 500 mm in the longitudinal direction and a length in the width direction (y-axis direction) perpendicular to the longitudinal direction of 10 to 100 mm. is there. The total thickness of the SOFC structure is 1 to 5 mm. The entire SOFC structure 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. Hereinafter, in addition to FIG. 1, the details of the SOFC structure will be described with reference to FIG. 2, which is a partial cross-sectional view of the SOFC structure corresponding to line 2-2 shown in FIG. 1. 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 made of a porous material having no electronic conductivity. As shown in FIG. 6 to be described later, a plurality of (six in this example) fuel gas passages 11 (through holes) extending in the longitudinal direction are provided in the support substrate 10 at predetermined intervals in the width direction. Is formed. In this example, each recess 12 includes 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 over the entire circumference (two side walls along the longitudinal direction and the width direction). A rectangular parallelepiped depression defined by two side walls).

The support substrate 10 can be made of, for example, CSZ (calcia stabilized zirconia). Alternatively, it may be composed of NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia), NiO (nickel oxide) and Y ₂ O ₃ (yttria), or MgO. (Magnesium oxide) and MgAl ₂ O ₄ (magnesia alumina spinel) may be used.

  The support substrate 10 may be configured to include “transition metal oxide or transition metal” and insulating ceramics. As the “transition metal oxide or transition metal”, NiO (nickel oxide) or Ni (nickel) is suitable. The transition metal can function as a catalyst for promoting a reforming reaction of the fuel gas (hydrocarbon-based gas reforming catalyst).

Further, as the insulating ceramic, MgO (magnesium oxide) or “mixture of MgAl ₂ O ₄ (magnesia alumina spinel) and MgO (magnesium oxide)” is preferable. Further, CSZ (calcia stabilized zirconia), YSZ (8YSZ) (yttria stabilized zirconia), Y ₂ O ₃ (yttria) may be used as the insulating ceramic.

  As described above, since the support substrate 10 contains “transition metal oxide or transition metal”, the gas containing the residual gas component before the reforming is supplied to the fuel through the numerous pores inside the porous support substrate 10. In the process of being supplied from the gas flow path 11 to the fuel electrode, the catalytic action can promote the reforming of the residual gas component before the reforming. In addition, the insulating property of the support substrate 10 can be ensured by the support substrate 10 containing insulating ceramics. As a result, insulation between adjacent fuel electrodes can be ensured.

  The thickness of the support substrate 10 is 1 to 5 mm. The porosity of the support substrate 10 is 20 to 60% after “reduction treatment” described later. Hereinafter, the porosity values of the other members are also values after the reduction treatment. The porosity was measured by polishing the cross section of the resin-embedded sample (after the reduction treatment) and analyzing the image (secondary electron image) of the cross section by SEM (scanning electron microscope). . The acceleration voltage of SEM was set to 5 kV, and the magnification of SEM was set to 5000 times or 7500 times. The measurement of the porosity was performed on arbitrary 10 cross-sections of the sample, and the average value thereof was adopted as the porosity value.

  Hereinafter, only the configuration on the upper surface side of the support substrate 10 will be described in consideration of the fact that the shape of the structure is vertically symmetrical. The same applies to the configuration of the lower surface side of the support substrate 10.

  As shown in FIGS. 2 and 3, the entire fuel electrode current collector 21 is embedded (filled) in each recess 12 formed in the upper surface (upper main surface) of the support substrate 10. 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 includes a bottom wall made of the material of the fuel electrode current collector 21 and a side wall (two side walls along the longitudinal direction) closed in the circumferential direction made of the material of the fuel electrode current collector 21 over the entire circumference. And two side walls along the width direction).

  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 four side surfaces and the bottom surface of each anode active portion 22 are in contact with the anode current collecting portion 21 in the recess 21a.

The fuel electrode active part 22 can 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. The porosity of the fuel electrode current collector 21 is 25 to 50%, and the porosity of the fuel electrode active part 22 is also 25 to 50%.

  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 oxidative ion (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”.

  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).

  In each recess 21b, an interconnector 30 and a seal portion 35 (corresponding to the “second seal portion”) are embedded (filled). Specifically, as shown in FIG. 3, in each recess 21b, the interconnector 30 is embedded (arranged) in the center of the recess 21b. Each interconnector 30 has a rectangular parallelepiped shape having two side walls along the longitudinal direction and two side walls along the width direction. The seal portion 35 is embedded at the peripheral edge portion of the recess 21b located around the interconnector 30 so as to be in contact with the entire periphery of the sidewall (inner wall) of the recess 21b and the entire periphery of the sidewall of the outer periphery of the interconnector 30. (Filled). That is, each seal portion 35 has a square frame shape. While the side surface of each interconnector 30 is not in contact with the fuel electrode 20 (current collector 21), the entire bottom surface of each interconnector 30 is in contact with the fuel electrode 20 (current collector 21).

The interconnector 30 is a fired body made of a dense material having electronic conductivity. The interconnector 30 can be composed of, for example, lanthanum chromite (LC). The chemical formula of lanthanum _{chromite, La 1-x A x Cr} 1-y-z B y O 3 ( provided that, A: Ca, at least one element Sr, is selected from Ba, B: Co, Ni, Mg, At least one element selected from Al, 0.05 ≦ x ≦ 0.2, 0.02 ≦ y ≦ 0.22, 0 ≦ z ≦ 0.05).

Alternatively, the interconnector 30 can be composed of titanium oxide. The chemical formula of titanium oxide is (A _1-x , B _x ) _1-z (Ti _1-y , D _y ) O ₃ (where A: at least one element selected from alkaline earth elements, B : At least one element selected from Sc, Y, and lanthanoid elements, D: transition metals of the fourth period, the fifth period, and the sixth period, and Al, Si, Zn, Ga, Ge, Sn, Sb, At least one element selected from Pb and Bi, 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.5, −0.05 ≦ z ≦ 0.05). In this case, it can be composed of (Sr, La) TiO ₃ (strontium titanate). The thickness of the interconnector 30 is 10 to 100 μm. The porosity of the interconnector 30 is 10% or less.

The seal part 35 is a fired body made of a dense material having electrical insulation. The seal part 35 contains, for example, a metal oxide, and preferably contains a metal oxide as a main component. Specifically, the metal oxide contains at least one oxide selected from the group consisting of (AE) ZrO ₃ , MgO, MgAl ₂ O ₄ , and Ce _x Ln _1-x O _2. Also good. Here, AE is an alkaline earth metal, Ln is at least one element selected from the group consisting of Y and a lanthanoid, and x satisfies 0 <x ≦ 0.3. Examples of elements corresponding to AE include Mg, Ca, Sr, and Ba. Moreover, transition metal oxides (for example, NiO, Mn ₃ O ₄ , Fe ₂ O ₃ , Cr ₂ O ₃ , CoO) may be included as a trace component. These components may exist as an oxide, or at least one selected from the group consisting of “(AE) ZrO ₃ , MgO, MgAl ₂ O ₄ , and Ce _x Ln _1-x O _2. It may be present in the form of a solid solution in the oxide. The average particle size of the metal oxide is preferably from 0.1 to 5.0 μm, more preferably from 0.3 to 4.0 μm. The thickness of the seal part 35 is 10 to 100 μm. The porosity of the seal part 35 is 10% or less.

  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, the upper surface (outer surface) of the seal portion 35, and the support substrate 10 With this main surface, one flat surface (the same flat surface as the main surface of the support substrate 10 when the recessed part 12 is not formed) is comprised. That is, no step is formed between the upper surface of the fuel electrode 20, the upper surface of the interconnector 30, the upper surface of the seal portion 35, and the main surface of the support substrate 10.

  A plurality of seal portions 35 and interconnectors 30 are provided on the outer peripheral surface (including the main surface) extending in the longitudinal direction of the support substrate 10 in a state where the fuel electrode 20, the interconnector 30, and the seal portions 35 are embedded in the recesses 12. The entire surface excluding the corresponding part is covered with the solid electrolyte membrane 40. More specifically, as shown in FIG. 4, the solid electrolyte membrane 40 is formed on the main surface of the support substrate 10 so as to cover the entire periphery of the outer peripheral surface of the seal portion 35. As a result, the seal portion 35 and the interconnector 30 are in contact with each other, and the seal portion 35 and the solid electrolyte membrane 40 are in contact with each other, while the interconnector 30 and the solid electrolyte membrane 40 are not in contact with each other.

  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. The porosity of the solid electrolyte membrane 40 is 10% or less.

  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, the seal portion 35, and the solid electrolyte membrane 40. ing. 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. 2, in this example, 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 substrate 60.

  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. The porosity of the air electrode current collector film 70 is 20 to 60%.

  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 the “electrical connection portion”, and the interconnector 30 corresponds to the “first portion of the electrical connection portion”. The air electrode current collector film 70 corresponds to the “second portion of the electrical connection portion”. Further, the “interconnector 30, the seal film 35, and the solid electrolyte film 40” made of a dense material correspond to the “gas seal portion”. In the present application, the “dense material” refers to a material having a porosity that is small enough to have a gas sealing function, and typically the porosity of the material is 10% or less.

As shown in FIG. 5, the fuel gas (hydrogen gas or the like) flows through the fuel gas flow path 11 of the support substrate 10 as shown in FIG. By exposing the upper and lower surfaces (particularly, each air electrode current collecting film 70) to “gas containing oxygen” (air or the like) (or flowing a gas containing oxygen along the upper and lower surfaces of the support substrate 10), the solid electrolyte An electromotive force is generated by an oxygen partial pressure difference generated between both side surfaces of the film 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. 6, 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. 5, from the entire SOFC structure (specifically, in FIG. 5, the interconnector 30 of the power generating element portion A on the foremost side and the air electrode of the power generating element portion A on the farthest side in FIG. The power is extracted (via 60).

(Production method)
Next, an example of a manufacturing method of the “horizontal stripe type” SOFC structure shown in FIG. 1 will be briefly described with reference to FIGS. 7 to 16, “g” at the end of the symbol of each member indicates that the member is “before firing”.

  First, a support substrate molded body 10g having the shape shown in FIG. 7 is produced. The molded body 10g of the support substrate is manufactured by using a method such as extrusion molding or cutting using a slurry obtained by adding a binder or the like to the material of the support substrate 10 (for example, CSZ). obtain. Hereinafter, the description will be continued with reference to FIGS. 8 to 16 showing partial cross sections corresponding to line 8-8 shown in FIG.

  As shown in FIG. 8, when the support substrate molded body 10g is manufactured, as shown in FIG. 9, the fuel electrode current collector is then placed in each recess formed on the upper and lower surfaces of the support substrate molded body 10g. Each of the molded parts 21g is embedded and formed. Next, as shown in FIG. 10, a molded body 22g of the fuel electrode active portion is embedded and formed in each recess formed in the outer surface of the molded body 21g of each fuel electrode current collector. The molded body 21g of each fuel electrode current collector and each of the fuel electrode active parts 22g use, for example, 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), It is embedded and formed using printing methods.

Subsequently, as shown in FIG. 11, each concave portion formed in “the portion excluding the portion where the molded body 22 g of the fuel electrode active portion is embedded” on the outer surface of the molded body 21 g of each fuel electrode current collector. A rectangular parallelepiped shaped interconnector molded body 30g is embedded and formed in the center. The molded body 30g of each interconnector is embedded and formed by using a slurry obtained by adding a binder or the like to the material of the interconnector 30 (for example, LaCrO ₃ ), using a printing method or the like. .

Next, as shown in FIG. 12, a molded body 35 g of a sealing material is embedded and formed in a peripheral portion located around the molded body 30 g of each concave portion. The molded body 35g of each sealing material is, for example, a printing method using a slurry obtained by adding a binder or the like to the powder of the material of the sealing portion 35 (for example, MgO or a composite material of MgO and CaZrO ₃ ). It is buried and formed using

  Next, as shown in FIG. 13, the outer peripheral surface extending in the longitudinal direction in the molded body 10g of the support substrate in a state where the molded bodies (21g + 22g) of the plurality of fuel electrodes and the molded bodies 30g, 35g are embedded and formed, respectively. A solid electrolyte membrane molded film 40g is formed on the entire surface excluding the respective portions where the plurality of molded bodies 30g and 35g are formed. 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. 14, a molded film 50 g of a 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 thus formed is fired in air at 1500 ° C. for 3 hours. As a result, a structure in which the air electrode 60 and the air electrode current collector film 70 are not formed in the SOFC structure shown in FIG. 1 is obtained.

  Next, as shown in FIG. 15, 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. 16, for each pair of adjacent power generation element portions, air is formed so as to straddle the air electrode forming film 60 g 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 60g, the solid electrolyte film 40, the interconnector 30, and the seal portion 35, an air electrode current collecting film forming film 70g 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.

  Then, the support substrate 10 in which the molded films 60g and 70g are thus formed is baked in air at 1050 ° C. for 3 hours. As a result, the SOFC structure shown in FIG. 1 is obtained. At this time, the Ni component in the support substrate 10 and the fuel electrode 20 is NiO by firing in an oxygen-containing atmosphere. Therefore, in order to acquire the conductivity of the fuel electrode 20, thereafter, a reducing fuel gas is flowed from the support substrate 10 side, and NiO is reduced at 700 to 1000 ° C. for 1 to 100 hours. This reduction process may be performed during power generation. The example of the method for manufacturing the SOFC structure shown in FIG. 1 has been described above.

(Configuration of gas seal)
As schematically shown in FIG. 17, in the above-described embodiment, the “dense layer in which the interconnector 30, the seal portion 35, and the solid electrolyte membrane 40 are continuously connected” is used to mix fuel gas and air. The gas seal function to prevent is exhibited. While a part (peripheral part) of the outer surface of the seal part 35 arranged at the peripheral part of the concave part 21 b formed on the outer surface of the fuel electrode 20 (current collector part 21) is covered with the solid electrolyte membrane 40. The outer surface of the interconnector 30 disposed in the center of the recess 21b is not covered with the solid electrolyte membrane 40.

  Here, as a conventional example for comparison with the above embodiment, as shown in FIG. 18, a mode in which the interconnector is embedded (filled) in the entire recess formed on the outer surface of the fuel electrode is considered. In this case, in order to suppress a decrease in gas sealing performance, as shown in FIG. 18, the peripheral portion of the outer surface of the interconnector is often covered with an electrolyte membrane. In general, an interconnector (particularly, an interconnector composed of lanthanum chromite) has a property of expanding during the reduction treatment described above (reduction expansion). Due to this reductive expansion, there is a problem that peeling occurs at the interface between the peripheral edge of the outer side surface of the interconnector and the inner side surface of the electrolyte membrane, and the “gas seal function” is likely to deteriorate. On the other hand, in the above embodiment, as described above, the dense membrane (solid electrolyte membrane 40) is not provided on the outer surface of the interconnector 30. Therefore, the “gas seal function” is not deteriorated due to the peeling due to the reduction expansion of the interconnector described above. In other words, it is possible to reliably suppress a decrease in the “gas seal function”.

  Moreover, in the said embodiment, as shown in FIG. 17, although the whole area of the bottom face of the rectangular parallelepiped interconnector 30 is contacting the fuel electrode 20 (current collection part 21), as shown in FIG. The middle part of the bottom surface of the interconnector 30 is in contact with the fuel electrode 20 (current collector 21), and the peripheral part located around the central part of the bottom surface of the interconnector 30 is in contact with the seal part 35. May be. Further, as shown in FIG. 20, a part of the peripheral edge portion on the bottom surface of the seal portion 35 may be configured to contact the interconnector 30.

Further, as shown in FIG. 21, an intermediate layer 38 may be interposed between the bottom surface of the interconnector 30 and the fuel electrode 20 (current collector 21). The intermediate layer 38 is made of a conductive material having a conductivity higher than that of the interconnector 30, and includes, for example, a mixed powder of NiO and Y ₂ O ₃ (yttria), a mixed powder of NiO and GDC (gadolinia doped ceria), NiO and LaCrO _3. Or the like. By inserting the intermediate layer 38, the interfacial resistance existing between the interconnector 30 and the fuel electrode current collector 21 can be greatly reduced. Therefore, the current path can be controlled so that the current passes through the “bottom surface of the interconnector 30 having a large area” rather than the “side surface of the interconnector 30 having a small area”, and the electrical resistance of the SOFC as a whole is reduced. can do.

In the configuration shown in FIG. 21, “the portion covering the entire circumference of the peripheral edge of the outer surface of the seal portion 35 (corresponding to the“ second seal portion ”)” in the solid electrolyte membrane 40 is replaced with the solid electrolyte membrane 40. The solid electrolyte membrane 40 may be composed of a dense membrane 37 (corresponding to the “first seal portion”) having a different constituent material. The dense film 37 can be made of, for example, GDC = (Ce, Gd) O ₂ (gadolinium-doped ceria).

  In this case, in the portion covering the outer surface of the fuel electrode 20 (current collector 21) in the “gas seal portion”, the “gas seal portion” includes the solid electrolyte membrane 40 as a part of the power generation element portion, A dense membrane 37 (corresponding to the “first seal portion”) made of a material different from that of the solid electrolyte membrane 40 and connected to the solid electrolyte membrane 40 is connected to the dense membrane 37 and is different from the dense membrane 37. A seal portion 35 (corresponding to the “second seal portion”) made of a dense constituent material and an interconnector 30 connected to the seal portion 35 are configured. In this case, the dense membrane 37 and the interconnector 30 do not contact each other, and the solid electrolyte membrane 40 and the seal portion 35 do not contact each other.

  In the configuration shown in FIG. 21, the seal portion 35 and the interconnector 30 are embedded in the recess 21b formed on the outer surface of the fuel electrode 20 (current collector 21). However, as shown in FIG. Only the interconnector 30 (and the intermediate layer 38) may be embedded in 21b. Alternatively, as shown in FIG. 23, only the seal portion 35 (and the intermediate layer 38) may be embedded in the recess 21b. Alternatively, as shown in FIG. 24, the recess 21 b is not formed on the outer surface of the fuel electrode 20 (current collector 21), and the interconnector 30 and the seal portion 35 may be formed on the main surface of the support substrate 10. .

  Similar to the configuration shown in FIG. 21, in the configuration shown in FIGS. 22 to 24, in the portion covering the outer surface of the fuel electrode 20 (current collector 21) in the “gas seal portion”, the “gas seal portion” “Solid electrolyte membrane 40 as a part of the power generation element portion” and “Dense membrane 40 connected to solid electrolyte membrane 40 and made of the same constituent material as solid electrolyte membrane 40 or dense membrane 37 made of a different constituent material” (Corresponding to the “first seal portion”) and “the seal portion 35 made of a dense constituent material that is connected to the dense film 40 or 37 and is different from the dense film 40 or 37” (the “second seal portion”) And "interconnector 30 connected to seal portion 35".

  Similar to the configuration shown in FIG. 21, in the configuration shown in FIGS. 22 to 24, when the “first seal portion” is the dense membrane 40 (= solid electrolyte membrane 40), the dense membrane 40 (= solid electrolyte membrane 40). And the interconnector 30 do not contact. When the “first seal portion” is the dense membrane 37 (≠ solid electrolyte membrane 40), the dense membrane 37 (≠ solid electrolyte membrane 40) and the interconnector 30 are not in contact with each other, and the solid electrolyte membrane 40 and the seal are sealed. The part 35 does not contact.

(Interface between seal part and anode current collector part)
Hereinafter, attention is focused on the interface between the seal portion 35 (particularly, the bottom surface of the seal portion 35) and the anode current collector 21, that is, the boundary between the dense layer and the porous layer. FIG. 25 shows a cross section (cross section along the stacking direction (film thickness direction), each element (each film) including the seal portion 35 and the anode current collector 21 according to the embodiment of the present invention after the reduction treatment. It is the figure which sketched an example of the image obtained by magnifying the cross section perpendicular | vertical to the plane direction of this with an electron microscope.

  In this specification, in this cross section, a line corresponding to the interface between the seal portion 35 (dense layer) and the fuel electrode current collector 21 (porous layer) (in the example shown in FIG. 25, a line segment L) is referred to as “boundary. Called “Line”. This boundary line can be defined as follows, for example. That is, a plurality of pores that are present facing the dense layer among a large number of pores included in the porous layer on the cross section are extracted. For each of the plurality of extracted pores, the point on the dense layer side in the region corresponding to the inside of the pore (in the example shown in FIG. 25, the uppermost point in the region corresponding to the inside of the pore) is plotted (FIG. In the example shown in FIG. 25, see a plurality of black dots). Using the plotted points and one of the well-known statistical techniques (eg, least squares method), a line (straight line or curve) passing through each of the plotted points is determined. . This line (in the example shown in FIG. 25, the line segment L) becomes the “boundary line”. In the example shown in FIG. 25, since the seal portion 35 is flat, the “boundary line” is a straight line. For example, when the seal portion 35 is warped or curved. The “boundary line” is a curved line. Further, the “boundary line” may be composed of a combination of a straight line and a curved line.

  With respect to the “boundary line” defined in this way, “joining rate” and “joining width” are defined as follows. The “joining rate” is the length of the “boundary line” (in the example shown in FIG. 25, the length of the line segment L in the figure) on the “boundary line” and the seal portion 35 and the fuel electrode current collector 21. Is defined as the ratio of the total length of the “parts” in contact with each other (a part that does not correspond to the pores). “Junction width” is defined as the average length of the “plurality of portions”.

  The present inventor found that after the reduction treatment, when the “joining rate” is 36 to 78%, compared with the case where the “joining rate” is not 36 to 78%, It has been found that the bonding strength increases at the “interface”. Hereinafter, test A in which this has been confirmed will be described.

(Test A)
In the test A, a seal part and a fuel electrode current collector part, which are a part of the fuel cell according to the present embodiment, are a seal part and a fuel electrode current collector part (hereinafter referred to as “joint body”). A plurality of samples having different combinations of materials and “joining rate” were produced. Specifically, as shown in Table 1, 10 types (combinations) were prepared. Twenty samples (N = 20) were made for each level.

  Each sample (joint) has a circular shape (diameter: about 2 cm) and a thickness of about 1 mm as viewed from above, and a circular shape (diameter: about 1 cm) and a thickness of about 100 μm as viewed from above. A laminated body in which a fuel electrode current collector was laminated. Each sample (joined body) was produced by co-firing a seal part and a fuel electrode current collector part. Adjustment of the “joining rate” is made by adjusting the particle size and specific surface area of powder (NiO powder, etc.) used for firing the fuel electrode current collector, the amount of organic components (binder, pore former), the seal part and the fuel. This was achieved by adjusting the co-firing temperature of the pole current collector.

Specifically, the average particle diameter of the powder was adjusted within a range of 0.5 to 5 μm. The specific surface area of the powder was adjusted within a range of 3 to 30 m ² / g. The amount (weight) of the organic component was adjusted within a range of 10 to 50% with respect to the total weight of the powder. Cellulose, carbon, PMMA, etc. were used as the pore former. The co-firing temperature was adjusted within the range of 850 to 1300 ° C. The firing time was adjusted within a range of 1 to 20 hours. After the firing, the above reduction treatment was performed on each sample. This reduction treatment was performed by exposing each sample to a hydrogen atmosphere at 800 ° C. for 5 hours.

  And the tensile strength was measured about each sample (joined body, after a reduction process). This measurement was made as follows. That is, jigs for a tensile test were attached to the upper and lower surfaces (the upper surface of the seal portion and the lower surface of the fuel electrode current collector), respectively. A force (tensile force) for pulling up and down was applied to the upper and lower jigs, and this tensile force was gradually increased. The magnitude of the tensile force (hereinafter referred to as “tensile strength”) at the time when the joining part (site near the interface between the seal part and the fuel electrode current collector) of the sample (joined body) peeled was measured. The measurement results of the tensile strength are as shown in Table 1. As a measurement result, an average value of N = 20 was adopted for each level.

  As can be understood from Table 1, when the “joining rate” is less than 36%, the tensile strength is small.

  Further, when the “joining rate” is larger than 78%, the tensile strength is small. The reason for this is not clear, but is considered as follows. In other words, an increase in the “joining rate” means that sintering of the seal portion and the fuel electrode current collector at the joining interface has progressed. As the sintering proceeds, the respective elements diffuse to each other, and phases having different compositions are generated at the bonding interface. When such a heterogeneous phase is generated, it can be a starting point for debonding of the bonding interface.

  From the above, it is considered that when the “joining rate” is large, the tensile strength becomes small as in the case where the “joining rate” is small.

  On the other hand, when the “joining rate” is 36 to 78%, the tensile strength is larger than when the “joining rate” is not 36 to 78%. In other words, after the reduction treatment, when the “joining rate” is 36 to 78%, compared to the case where the “joining rate” is not 36 to 78%, the “interface between the seal portion and the fuel electrode current collector”. It can be said that the bonding strength is high.

  In addition, the present inventor, after the reduction treatment, when the “joining rate” is 36 to 78% and the “joining width” is 0.3 to 3.3 μm, It has also been found that the bonding strength is particularly increased at the “interface with the electric part”. Hereinafter, test B in which this has been confirmed will be described.

(Test B)
In Test B as well as Test A, regarding the “joint” of the seal portion and the anode current collector that is a part of the fuel cell according to the present embodiment, the material of the seal portion and the material of the anode current collector A plurality of samples having different combinations of “joining rate” and “joining width” were produced. Specifically, as shown in Table 2, ten kinds of levels (combinations) were prepared. Twenty samples (N = 20) were made for each level. The shape of each sample (joint) was the same as that of Test A. The “joining rate” of each sample (joined body, after reduction treatment) is in the range of 36 to 78%. Adjusting the “joining width” is the same as adjusting the “joining rate”, the particle diameter and specific surface area of the powder (NiO powder, etc.) used for firing the fuel electrode current collector, organic components (binder, pore former) This was achieved by adjusting the amount of selenium and the co-firing temperature. Each adjustment range of the average particle diameter of the powder, the specific surface area of the powder, the amount (weight) of the organic component, the firing temperature, and the firing time is the same as in the case of Test A described above. The conditions for the reduction treatment are also the same as in the case of test A described above.

  And about each sample (joined body, after a reduction process), the tensile strength was measured by the method similar to the test A. FIG. The measurement results are as shown in Table 2. As can be understood from Table 2, when the “joining rate” is 36 to 78%, the “joining width” is not 0.3 to 3.3 μm when the “joining width” is 0.3 to 3.3 μm. Compared to the case, the tensile strength is large. That is, after the reduction treatment, when the “joining rate” is 36 to 78%, when the “joining width” is 0.3 to 3.3 μm, “at the interface between the seal portion and the fuel electrode current collector”. It can be said that the bonding strength is particularly high.

  Note that “the joining rate is 36 to 78%” (and the joining width is 0.3 to 3.3 μm) may be established for any one cross section including the seal portion and the fuel electrode current collector. Alternatively, “the joining rate is 36 to 78%” (and the joining width is 0.3 to 3.3 μm) is an arbitrary plurality of cross sections (for example, parallel to a certain direction) including the seal portion and the anode current collector. It is necessary to be established for each of two cross sections and two cross sections parallel to a direction orthogonal to the direction.

  The present invention is not limited to the above embodiment, and various modifications can be employed within the scope of the present invention. For example, in the above-described embodiment, the stack constituting the fuel cell exists alone (see FIG. 1), but this stack may exist as a part of an entire apparatus. Moreover, in the said embodiment, as shown in FIG. 7 etc., the planar shape (shape when it sees from the direction perpendicular | vertical to the main surface of the support substrate 10) of the recessed part 12 formed in the support substrate 10 becomes a rectangle. However, it may be, for example, a square, a circle, an ellipse, or a long hole shape.

  Moreover, in the said embodiment, although the several recessed part 12 is formed in each of the upper and lower surfaces of the flat support substrate 10, and the several electric power generation element part A is provided, as shown in FIG. A plurality of recesses 12 may be formed only on one side of the ten and a plurality of power generation element portions 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.

  DESCRIPTION OF SYMBOLS 10 ... Support substrate, 11 ... Fuel gas flow path, 12 ... Recessed part, 20 ... Fuel electrode, 21 ... Fuel electrode current collecting part, 21a, 21b ... Recessed part, 22 ... Fuel electrode active part, 30 ... Interconnector, 35 ... Seal , 37 ... dense membrane, 38 ... intermediate layer, 40 ... solid electrolyte membrane, 50 ... reaction preventing membrane, 60 ... air electrode, 70 ... air electrode current collector membrane, A ... power generation element portion

Claims (5)

A support substrate having a gas flow path formed therein;
A plurality of power generating element portions each provided at a plurality of locations separated from each other on the main surface of the support substrate, wherein at least a fuel electrode, a solid electrolyte, and an air electrode are laminated;
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
Densely provided between one set or a plurality of adjacent power generation element portions to prevent mixing of the first gas supplied to the fuel electrode and the second gas supplied to the air electrode A gas seal portion made of a constituent material;
In a fuel cell comprising
First recesses having a bottom wall made of the material of the support substrate and a side wall made of the material of the support substrate are formed in the plurality of locations on the main surface of the support substrate, respectively.
In each of the first recesses, the corresponding fuel electrode of the power generation element unit is embedded,
Each of the electrical connection portions includes a first portion made of a dense material and a second portion connected to the first portion and made of a porous material. Connected to one fuel electrode of the adjacent power generation element portion and the second portion, the second portion is connected to the other air electrode of the adjacent power generation element portion and the first portion,
In the part covering the outer surface of each buried fuel electrode in the gas seal part, the gas seal part is connected to the dense solid electrolyte as a part of the power generation element part and the solid electrolyte. A first seal portion made of a dense constituent material the same as or different from the solid electrolyte, a second seal portion connected to the first seal portion and made of a dense constituent material different from the first seal portion, and A first portion of the electrical connection portion connected to the second seal portion, and configured so as not to contact the first seal portion and the first portion of the electrical connection portion,
In a state where the fuel cell is a reductant that has been heat-treated in a reducing atmosphere, the first portion in a cross section including the second seal portion made of a dense material and the fuel electrode made of a porous material. The total length of a plurality of portions where the second seal part and the fuel electrode are in contact with each other on the boundary line with respect to the length of the boundary line corresponding to the interface between the two seal parts and the fuel electrode A fuel cell having a bonding rate of 36 to 78%. The fuel cell according to claim 1, wherein
In the state where the fuel cell is a reductant that has been heat-treated in a reducing atmosphere, the joining is an average length of the plurality of portions where the second seal portion and the fuel electrode are in contact with each other on the boundary line A fuel cell having a width of 0.3 to 3.3 μm. The fuel cell according to claim 1 or 2,
Second recesses having a bottom wall made of the material of the fuel electrode and a side wall made of the material of the fuel electrode 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 and the corresponding second seal portion are embedded, respectively.
In each of the second recesses,
A first portion of the electrical connection portion is embedded in a central portion of the second recess,
The second seal portion is a peripheral portion located around the central portion of the second recess, and the entire periphery of the side wall of the second recess and the outer periphery of the first portion of the electrical connection portion Buried in contact with the entire circumference of the
In each of the second recesses,
The fuel cell, wherein the entire periphery of the outer peripheral surface of the second seal portion is covered with the first seal portion. The fuel cell according to claim 3, wherein
In each of the second recesses,
A central portion of the bottom surface of the first portion of the electrical connection portion is in contact with the fuel electrode, and a peripheral portion located around the central portion of the bottom surface of the first portion of the electrical connection portion is the second seal portion. A fuel cell in contact with the fuel cell. The fuel cell according to claim 3, wherein
In each of the second recesses,
A central portion of the bottom surface of the first portion of the electrical connection portion is in contact with the fuel electrode via an intermediate layer made of a conductive material having a conductivity higher than that of the first portion of the electrical connection portion, and A fuel cell, wherein a peripheral edge located around the central portion of the bottom surface of the first portion of the general connection portion is in contact with the second seal portion.

Images