JP5050124B1 - Fuel cell structure - Google Patents

Abstract

A structure of a fuel cell of “horizontal stripe type”, in which when a support substrate receives an external force, the support substrate is not easily deformed, has a high power generation output, and generates cracks around a fuel electrode. Provide something that can be suppressed.
A plurality of power generating element portions A electrically connected in series are arranged at a predetermined interval on a main surface of a flat support substrate 10 in which a fuel gas flow path 11 is formed. . On the main surface of the support substrate 10, recesses 12 defined by side walls and bottom walls closed in the circumferential direction are formed at positions corresponding to the respective power generating element portions A. In each recess 12, a fuel electrode current collector 21 of the corresponding power generation element portion A is embedded. A concave portion 21 a defined by a side wall and a bottom wall closed in the circumferential direction is formed on the outer surface of each fuel electrode current collector 21. In each recess 21a, the anode active portion 22 of the corresponding power generation element portion A is embedded.
[Selection] Figure 2

Description

  The present invention relates to a fuel cell structure.

  Conventionally, “a porous support substrate having no electron conductivity in which a gas flow path is formed” and “a plurality of locations separated from each other on the surface of the support substrate, a fuel electrode, a solid A plurality of power generation element portions in which an electrolyte and an air electrode are stacked, and one fuel electrode of each of the adjacent power generation element portions provided between one or a plurality of adjacent power generation element portions, There is known a structure of a solid oxide fuel cell provided with “one or more electrical connection parts having electronic conductivity for electrically connecting the other air electrode” (for example, Patent Document 1). 2). Such a configuration is also called a “horizontal stripe type”.

  Hereinafter, attention is focused on the shape of the support substrate. In the “horizontal stripe type” solid oxide fuel cell structure described in Patent Document 1, the support substrate has a cylindrical shape. On the surface (cylindrical surface) of the cylindrical support substrate, a plurality of “annular grooves” for embedding the fuel electrode are respectively formed at a plurality of axial positions (see FIG. 3). Therefore, the outer diameter of the portion where the “annular groove” is formed in the support substrate is small. For this reason, it can be said that this structure is a structure that is easily deformed when an external force in the bending direction or the twisting direction is applied to the support substrate.

  In the structure of the “horizontal stripe type” solid oxide fuel cell described in Patent Document 2, the support substrate has a flat plate shape having a longitudinal direction. A “long groove extending in the longitudinal direction and opened in the longitudinal direction” for embedding a fuel electrode or the like is formed on the main surface (plane) of the flat support substrate (see FIG. 3B). . Therefore, the thickness of the portion where the “long groove” is formed in the support substrate is small.

  In addition, the “long groove” has side walls extending in the longitudinal direction at both ends in the width direction orthogonal to the longitudinal direction, and does not have side walls extending in the width direction at both ends in the longitudinal direction. That is, the “long groove” does not have a side wall closed in the circumferential direction. Therefore, the frame surrounding the “long groove” is not formed on the support substrate. Due to these reasons, this structure can be said to be a structure that is easily deformed particularly when an external force in the twisting direction is applied to the support substrate. From the above, in the structure of the “horizontal stripe” fuel cell, it is desired to suppress the deformation of the support substrate when the support substrate receives an external force.

  Furthermore, in the fuel cell structure described above, the fuel electrode is usually used mainly for the activation of the current collector and the chemical reaction (see formula (2) described later). And an active part. In this configuration, it is desired to increase the power generation output and suppress the generation of cracks around the fuel electrode by devising the arrangement of the fuel electrode current collector and the fuel electrode active part.

JP-A-8-106916 JP 2008-226789 A

  The present invention relates to a structure of a “horizontal stripe” fuel cell, in which the support substrate is not easily deformed when the support substrate receives an external force, the power generation output is high, and cracks occur around the fuel electrode. It aims at providing what can control.

  The structure of the fuel cell according to the present invention includes a flat plate-like porous support substrate that has a gas flow path formed therein and does not have electron conductivity, and a main surface of the flat plate-like support substrate that is separated from each other. Provided at each of a plurality of locations, `` a plurality of power generation element portions formed by laminating at least a fuel electrode, a solid electrolyte, and an air electrode '', and provided between one or a plurality of adjacent power generation element portions, One or a plurality of electrical connection portions having electronic conductivity for electrically connecting one fuel electrode and the other air electrode of the adjacent power generation element portions. That is, this structure is a “horizontal stripe type” fuel cell structure.

  The characteristics of the fuel cell structure according to the present invention are as follows. That is, the plurality of locations on the main surface of the flat support substrate include a bottom wall made of the support substrate material and a circumferentially closed side wall made of the support substrate material over the entire circumference. One recess is formed. In each of the first recesses, a corresponding current collecting portion of the fuel electrode of the power generating element portion is embedded. On the outer surface of each buried fuel electrode current collector, a bottom wall made of the material of the fuel electrode current collector and a side wall closed in the circumferential direction made of the material of the fuel electrode current collector over the entire circumference. Each of the second recesses having the shape is formed. And the active part of the fuel electrode of the said electric power generation element part corresponding to each said 2nd recessed part is each embed | buried. Here, the fuel electrode includes a fuel electrode current collector and a fuel electrode active part. The anode active portion has a higher content ratio of a substance having oxygen ion conductivity than the anode current collecting portion.

  Thus, in the “horizontal stripe type” fuel cell structure according to the present invention, each first recess for embedding the fuel electrode current collector has a side wall closed in the circumferential direction. In other words, a frame surrounding each first recess is formed on the support substrate. Therefore, it can be said that this structure is a structure that is not easily deformed when the support substrate receives an external force.

  In addition, the fuel electrode active portion is embedded in a recess formed on the outer surface of the fuel electrode current collector. Therefore, the area of the interface between the fuel electrode current collector and the fuel electrode active part is reduced as compared with the case where the configuration in which the fuel electrode active part is laminated (contacted) on the outer surface of the fuel electrode current collector is employed. Can be big. Therefore, the electron conductivity between the fuel electrode current collector and the fuel electrode active part can be increased. As a result, the power generation output of the fuel cell can be increased.

  Moreover, the recessed part for embedding a fuel electrode active part has the bottom wall which consists of material of a fuel electrode current collection part, and the side wall closed in the circumferential direction which consists of material of a fuel electrode current collection part over the perimeter. That is, the entire side surface and bottom surface of the buried anode active portion are covered with the anode current collecting portion. Therefore, a configuration in which the fuel electrode current collector is interposed between the fuel electrode active portion and the support substrate (a configuration in which the fuel electrode active portion and the support substrate are not in contact) is obtained. Therefore, various components (for example, Mg, Al, Fe) constituting the support substrate can be prevented from diffusing into the anode active portion, and a decrease in the active function of the anode active portion due to such diffusion can be suppressed. . As a result, the power generation output of the fuel cell can be increased.

  In general, the Ni content (volume) ratio of the fuel electrode active portion is larger than the Ni content ratio of the support substrate. Therefore, in the configuration in which the anode active portion and the support substrate are in contact, NiO in the anode active portion is likely to diffuse into the support substrate. On the other hand, as described above, in the configuration in which the fuel electrode current collector is interposed between the fuel electrode active part and the support substrate, the Ni content ratio of the fuel electrode current collector part is the Ni content ratio of the fuel electrode active part. Due to the same degree, the diffusion of NiO in the fuel electrode active portion to the support substrate can be suppressed. Therefore, a decrease in the active function of the fuel electrode active part due to such diffusion can be suppressed. As a result, the power generation output of the fuel cell can be increased.

  In addition, in the above configuration, the entire area of the side surface and the bottom surface of the buried anode active portion is covered with the anode current collecting portion. In other words, a three-layer interface (three points) where all of the fuel electrode active part, the fuel electrode current collector part, and the support substrate gather is not formed. When a three-layer interface is formed, cracks due to stress concentration are likely to occur near the three-layer interface during firing or the like. As described above, in the above configuration, generation of cracks around the fuel electrode can be suppressed.

1 is a perspective view showing a structure of a fuel cell according to the present invention. It is sectional drawing corresponding to the 2-2 line of the structure of the fuel cell 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. It is a figure for demonstrating the operating state of the structure 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 structure 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 structure 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 structure 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 structure 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 structure 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 structure 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 structure 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 structure shown in FIG. 1. FIG. 8 is a cross-sectional view corresponding to FIG. 2 in an eighth stage in the manufacturing process of the fuel cell structure shown in FIG. 1. It is sectional drawing corresponding to FIG. 2 of the 1st modification of the structure of the fuel cell concerning this invention. It is sectional drawing corresponding to FIG. 2 of the 2nd modification of the structure of the fuel cell concerning this invention. It is sectional drawing corresponding to FIG. 2 of the 3rd modification of the structure of the fuel cell concerning 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 viewed from above is, for example, a rectangle having a length of 5 to 50 cm in the longitudinal direction and a length of 1 to 10 cm in the width direction (y-axis direction) perpendicular to the longitudinal direction. 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. 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 circumferentially closed side wall made of the material of the fuel electrode current collector 21 (two side walls and a width along the longitudinal direction). Two side walls extending in the direction), and a rectangular parallelepiped-shaped depression.

  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.

  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 the material of the fuel electrode current collector 21 and a side wall made of the material of the fuel electrode current collector 21 over the entire circumference (two side walls and a width along the longitudinal direction). Two side walls extending in the direction), and a rectangular parallelepiped-shaped depression.

  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 surfaces and the bottom surface of each interconnector 30 are in contact with the fuel electrode current collector 21 in the recess 21b.

  In each recess 12, the shortest distance L1 (see FIG. 3) between the side wall along the longitudinal direction (x-axis direction) of the recess 12 and the side wall along the longitudinal direction (x-axis direction) of the recess 21a is 0.10 to 0.10. 2.0 mm, and the shortest distance L2 (see FIG. 3) between the side wall along the width direction (y-axis direction) of the recess 12 and the side wall along the width direction (y-axis direction) of the recess 21a is 0.10. ~ 2.0 mm. That is, the shortest distance between the side wall of the recess 12 and the side wall of the recess 21a is 0.10 mm or more.

  Hereinafter, when viewed from a direction perpendicular to the main surface of the support substrate 10 (see FIG. 3), the area of the recess 12, the area of the buried anode active portion 22, and the area of the buried interconnector 30 are as follows. I will add about the ratio.

  In the configuration shown in FIG. 3, when viewed from a direction perpendicular to the main surface of the support substrate 10, the area of the fuel electrode active part 22 is preferably larger than the area of the interconnector 30 for each recess 12. Specifically, for each recess 12, the ratio of the area of the interconnector 30 to the area of the recess 12 is preferably 3 to 30%, and the ratio of the area of the anode active portion 22 to the area of the recess 12 is It is suitable that it is 30 to 90%.

  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 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”.

The interconnector 30 can be composed of, for example, LaCrO ₃ (lanthanum chromite). LaCrO ₃ may be (La, Ca) CrO ₃ (calcium doped planan chromite) doped with Ca and Sr, or (La, Sr) CrO ₃ (strontium doped planan 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. 2, in this example, the solid electrolyte membrane 40 includes the upper surface of the fuel electrode 20 (current collector 21 + active portion 22), both end portions in the longitudinal direction on the upper surface of the interconnector 30, and the support substrate. 10 main surfaces are covered. 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. 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 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, as shown in FIG. 4, the fuel gas (hydrogen gas or the like) flows through the fuel gas flow path 11 of the support substrate 10 with respect to the “horizontal stripe” SOFC structure described above. 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. 5, a 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. 4, the SOFC structure as a whole (specifically, the interconnector 30 of the power generating element part A on the frontmost side in FIG. 4 and the air electrode of the power generating element part A on the innermost 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. 6 to 14, “g” at the end of the reference numeral of each member represents that the member is “before firing”.

  First, a support substrate molded body 10g having the shape shown in FIG. 6 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. 7 to 14 showing partial cross sections corresponding to line 7-7 shown in FIG. 6.

  When the support substrate molded body 10g is manufactured as shown in FIG. 7, the fuel electrode current collector is then placed in each recess formed in the upper and lower surfaces of the support substrate molded body 10g as shown in FIG. Each of the molded parts 21g is embedded and formed. Next, as shown in FIG. 9, 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. 10, in 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. The interconnector molded bodies 30g are respectively embedded and formed. 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. 11, the outer periphery extending in the longitudinal direction of the molded body 10g of the support substrate in a state in which the molded body (21g + 22g) of the plurality of fuel electrodes and the molded body 30g of the plurality of interconnectors are respectively embedded and formed. A solid electrolyte membrane molded film 40g is formed on the entire surface excluding the central portion in the longitudinal direction of each portion where the plurality of interconnector molded bodies 30g 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. 12, a reaction prevention film molding film 50g is formed on the outer surface of the solid electrolyte membrane molding body 40g in contact with the fuel electrode molding body 22g. 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. 13, 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. 14, for each pair of adjacent power generation element portions, air is formed so as to straddle the air electrode molding 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, and the interconnector 30, a formed film 70g of the air electrode current collecting film 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. The example of the method for manufacturing the SOFC structure shown in FIG. 1 has been described above.

(Action / Effect)
As described above, in the “horizontal stripe type” SOFC structure according to the embodiment of the present invention, the fuel electrode 20 (current collector 21) formed on the upper and lower surfaces of the support substrate 10 is embedded. Each of the plurality of recesses 12 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.

  In addition, the support substrate 10 and the embedded member are filled in the recesses 12 of the support substrate 10 such as the fuel electrode 20 (current collector 21 + active portion 22) and the interconnector 30 without any gaps. And are co-sintered. Therefore, a sintered body having high bondability between members and high reliability can be obtained.

  Further, the anode active portion 22 is embedded in a recess 21 a formed on the outer surface of the anode current collecting portion 21. Therefore, as compared with the case where the configuration in which the anode active portion 22 is stacked (contacted) on the outer surface of the anode current collecting portion 21 is adopted, the anode current collecting portion 21 and the anode active portion 22 are separated from each other. The area of the interface can be increased. Therefore, the electron conductivity between the fuel electrode current collector 21 and the fuel electrode active part 22 can be increased. As a result, the power generation output of the fuel cell can be increased.

  Moreover, the recessed part 21a for embedding the anode active part 22 has the bottom wall which consists of the material of the anode current collection part 21, and the side wall closed in the circumferential direction which consists of the material of the anode current collection part 21 over the perimeter. And have. That is, the entire area of the side surface and the bottom surface of the buried anode active portion 22 is covered with the anode current collecting portion 21. Therefore, a configuration in which the fuel electrode current collector 21 is interposed between the fuel electrode active portion 22 and the support substrate 10 (a configuration in which the fuel electrode active portion 22 and the support substrate 10 are not in contact) is obtained. Therefore, various components (for example, Mg, Al, Fe) constituting the support substrate 10 can be prevented from diffusing into the anode active portion 22, and the active function of the anode active portion 22 can be reduced due to such diffusion. Can be suppressed. As a result, the power generation output of the fuel cell can be increased.

  In general, the Ni content (volume) ratio (for example, about 40% by volume) of the fuel electrode active portion is larger than the Ni content ratio (for example, about 15% by volume) of the support substrate. Therefore, in the configuration in which the anode active portion and the support substrate are in contact, NiO in the anode active portion is likely to diffuse into the support substrate. On the other hand, in the configuration in which the anode current collector 21 is interposed between the anode active portion 22 and the support substrate 10 as described above, the Ni content ratio (for example, 40% by volume) of the anode current collector 21 is provided. Is about the same as the Ni content of the anode active portion 22, the diffusion of NiO in the anode active portion 22 to the support substrate 10 can be suppressed. Therefore, a decrease in the active function of the fuel electrode active part 22 due to such diffusion can be suppressed. As a result, the power generation output of the fuel cell can be increased.

  Further, in the above configuration, the entire area of the side surface and the bottom surface of the buried anode active portion 22 is covered with the anode current collecting portion 21. In other words, the three-layer interface (three points) where all of the anode active part 22, the anode current collecting part 21, and the support substrate 10 gather is not formed. When a three-layer interface is formed, cracks due to stress concentration are likely to occur near the three-layer interface during firing or the like. As described above, in the above configuration, the generation of cracks around the fuel electrode 20 (current collector 21 + active part 22) can be suppressed.

  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, two side surfaces and a bottom surface along the width direction (y-axis direction) of the rectangular interconnector 30 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.

  Further, in the above-described embodiment, a plurality of power generation element portions A are provided on each of 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.

  Further, in the above embodiment, the solid electrolyte membrane 40 includes the outer surface of the fuel electrode 20 (current collector 21 + active portion 22), both end portions in the longitudinal direction of the outer surface of the interconnector 30, and the main surface of the support substrate 10. Covering. 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.

  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 embodiment, as shown in FIG. 6 and the like, the planar shape of the recess 12 formed in the support substrate 10 (the shape when viewed from the direction perpendicular to the main surface of the support substrate 10) is a rectangle. However, it may be, for example, a square, a circle, an ellipse, or a long hole shape.

  In the above embodiment, the entire interconnector 30 is embedded in each recess 12, but only a part of the interconnector 30 is embedded in each recess 12, and the remaining portion of the interconnector 30 is recessed 12. May protrude outside (that is, protrude from the main surface of the support substrate 10).

  Moreover, in the said embodiment, although the angle (theta) which the bottom wall and side wall in the recessed part 12 make is 90 degrees, as shown in FIG. 15, angle (theta) may be 90-135 degrees. Moreover, in the said embodiment, as shown in FIG. 16, the part where the bottom wall and side wall in the recessed part 12 cross | intersect is the circular arc shape of the radius R, and the ratio of the radius R with respect to the depth of the recessed part 12 is 0. .01 to 1 may be used.

  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.

  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, 40 ... Solid Electrolyte membrane, 50 ... reaction preventing membrane, 60 ... air electrode, 70 ... air electrode current collector membrane, A ... power generation element section

Claims (4)

A flat porous 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 flat support substrate, and a stack of at least a fuel electrode, a solid electrolyte, and an air electrode;
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 structure comprising:
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 over the entire circumference at the plurality of locations on the main surface of the flat support substrate. Each formed,
In each of the first recesses, a corresponding current collecting part of the fuel electrode of the power generating element part is embedded,
On the outer surface of each buried fuel electrode current collector, a bottom wall made of the material of the fuel electrode current collector and a side wall closed in the circumferential direction made of the material of the fuel electrode current collector over the entire circumference. A second recess having each of
The active portion of the fuel electrode that is the active portion of the fuel electrode of the power generation element portion corresponding to each of the second recesses and has a large content ratio of the substance having oxygen ion conductivity with respect to the corresponding fuel electrode current collector portion A fuel cell structure in which each is embedded. The fuel cell structure according to claim 1,
The fuel cell structure according to any one of the first recesses, wherein a shortest distance between a side wall of the first recess and a side wall of the second recess is 0.10 mm or more. In the structure of the fuel cell according to claim 1 or 2,
The structure of the fuel cell, wherein the ratio of the area of the second recess to the area of the first recess is 30 to 90% when viewed from the direction perpendicular to the main surface of the support substrate. body. In the structure of the fuel cell according to any one of claims 1 to 3,
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,
The fuel electrode current collector is formed over the entire circumference of the bottom wall made of the material of the fuel electrode current collector at a position different from the position where the second recess is formed on the outer surface of each buried fuel electrode current collector. A third recess having a circumferentially closed side wall made of a material of the electric part is formed,
A structure of a fuel cell, wherein the first portion of the corresponding electrical connection portion is embedded in each third recess.

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