JP2015065047A - Solid oxide fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide type fuel battery cell capable of improving gas shielding performance.SOLUTION: Solid electrolyte membranes 40 are extended from both sides of one and the other power generation element parts A and arranged on both end parts of an interconnector 30 in layers. An air electrode collector part 70 is extended from the surface of an air electrode 60 of the other power generation element part A to one power generation element part A side and laminated on the surface of the interconnector 30. An end face and an end part surface of a solid electrolyte membrane 40 of the other power generation element part A on the interconnector 30 side are covered with a cover seal layer 71. The cover seal layer 71 is joined to the surface of the interconnector 30 or an insulating seal portion.

Description

  The present invention relates to a solid oxide fuel cell.

  Conventionally, a flat porous support substrate having a gas flow path formed therein, and a plurality of power generating element portions respectively provided at a plurality of locations separated from each other on the main surface of the flat support substrate, An electric connection part for electrically connecting one fuel electrode and the other air electrode of the matching power generation element part, and at a plurality of locations on the main surface of the flat support substrate, A solid oxide fuel cell is known in which first recesses having side walls closed in a direction are formed, and in each first recess, a fuel electrode current collector of a corresponding power generation element unit is embedded. (For example, refer to Patent Document 1).

  In Patent Document 1, a second recess is formed in a fuel electrode current collector embedded in each first recess, a fuel electrode active unit is embedded in the second recess, and a fuel electrode current collector is provided. A third recess is formed in the part, and an interconnector is embedded in the third recess.

  A solid electrolyte membrane is formed on the surface of the support substrate except for the central portion in the longitudinal direction of the cell in the interconnector, and a gas seal layer composed of a dense membrane is formed by the interconnector and the solid electrolyte membrane, which is supplied to the fuel electrode. The fuel gas and the air supplied to the air electrode are prevented from being mixed.

JP 2012-38718 A

  However, in Patent Document 1 described above, a fuel electrode current collector is embedded in the first recess of the support substrate, and a fuel electrode active unit is embedded in the second recess of the fuel electrode current collector. Since the interconnector was embedded in the third recess of the part and fired in this state to produce a solid oxide fuel cell, the firing shrinkage behavior of the material constituting the recess and the material embedded in the recess Depending on the difference in thermal expansion coefficient, etc., there is a risk that a gap will be formed between the wall surface constituting the recess and the material embedded in the recess.

  Due to the formation of this gap, stress is generated in the solid electrolyte laminated on the boundary between the wall surface constituting the recess and the embedded material, the solid electrolyte is cracked, or the solid electrolyte laminated on the interconnector is The fuel gas that peels off and flows in the support substrate leaks out of the support substrate, and there is a problem that the gas blocking performance between the fuel gas supplied to the fuel electrode and the air supplied to the air electrode is lowered.

  An object of this invention is to provide the solid oxide fuel cell which can improve gas interruption | blocking performance.

The solid oxide fuel cell of the present invention is provided in each of a flat porous support substrate having a gas flow path formed therein and a plurality of locations separated from each other on the main surface of the support substrate, Provided between a plurality of power generation element portions in which a fuel electrode, a solid electrolyte, and an air electrode are laminated, and the adjacent power generation element portions, and the fuel electrode of one power generation element portion and the other power generation element portion The fuel electrode has a larger amount of the material having ion conductivity than the fuel electrode current collector and the fuel electrode current collector. Each of the plurality of locations on the main surface of the support substrate is provided with a first recess having a bottom wall and a side wall closed in the circumferential direction, and the fuel electrode is provided in each first recess. Current collectors are respectively embedded and the first The anode active portion is embedded in a second recess formed on the outer surface of the anode current collector embedded in the portion, and the second recess of the anode current collector embedded in the first recess is formed. A solid electrolyte laminated on the fuel electrode active portion is formed by embedding a conductive dense body constituting a part of the electrical connection portion in a third recess formed on the outer surface at a position different from the formed position. Extending from both sides of the one and the other power generating element part, and laminated on both ends of the conductive dense body, or both ends of the insulating seal part provided at both ends of the conductive dense body, Further, an air electrode current collector that constitutes a part of the electrical connection portion is extended from the air electrode surface of the other power generation element portion to the one power generation element portion side, and the surface of the conductive dense body And the electric conductivity of the solid electrolyte of the one power generation element portion. The end face and the end surface of the dense electrolyte side is coated with a coating sealing layer, characterized in that the coating sealing layer is bonded to the conductive dense material or a surface of the insulating seal portion.

  In the solid oxide fuel cell of the present invention, the end surface and the end surface of the solid electrolyte of one power generation element portion on the conductive dense body side are covered with the covering seal layer, and the covering seal layer is the conductive dense body. Alternatively, since it is bonded to the surface of the insulating seal portion, gas leaks between the solid electrolyte and the conductive dense body or insulating seal portion, and from the end surface of the solid electrolyte on the conductive dense body side. Can be suppressed, and the gas shut-off performance can be improved.

(A) is a perspective view which shows a solid oxide fuel cell, (b) is a top view which shows the state by which the fuel electrode and the interconnector (electroconductive dense body) were embed | buried in the recessed part. (A) is sectional drawing corresponding to the 2-2 line of the solid oxide fuel cell shown in FIG. 1 (a), (b) is sectional drawing which shows a 1st recessed part and its vicinity. It is a figure for demonstrating the operating state of the solid oxide fuel cell shown in FIG. It is sectional drawing which shows the state which formed the insulating sealing layer in four side surfaces of a 3rd recessed part so that an interconnector (conductive dense body) may be enclosed. The form which the air electrode current collection part of the other fuel battery cell is extended beyond one fuel battery cell side end of an interconnector (conductive dense body), and is laminated | stacked on the surface of the covering sealing layer is shown. It is sectional drawing. It is a perspective view which shows the molded object of the support substrate of FIG. (A) is sectional drawing corresponding to the 7-7 line | wire of FIG. 6, (b) is sectional drawing which shows the state which formed each layer in the 1st recessed part. It is a top view which shows the interconnector with which 4 side surfaces were embed | buried under the 3rd recessed part which consists of material of a fuel electrode current collection part.

  FIG. 1A shows a solid oxide fuel cell (hereinafter also referred to as a cell) according to an embodiment of the present invention. This cell has a flat plate shape having a longitudinal direction (x-axis direction). A plurality of (four in this embodiment) identical power generation element portions A electrically connected in series to the upper and lower surfaces (main surfaces (planes) on both sides parallel to each other) of the porous support substrate 10 Are arranged at a predetermined interval in the longitudinal direction, and have a so-called “horizontal stripe type” structure.

The shape of the cell viewed from above is, for example, a rectangle having a side length of 5 to 50 cm in the longitudinal direction and a length in the width direction (y-axis direction) orthogonal to the longitudinal direction of 1 to 10 cm. The thickness of this cell is 1-5 mm. This cell 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. 1A, details of this cell will be described with reference to FIG. 2A which is a partial sectional view corresponding to line 2-2 shown in FIG. 1A of this cell. .

  FIG. 2A is a partial cross-sectional view showing a configuration (part of) each of a representative 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 of the 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 electron conductivity (insulating). Inside the support substrate 10, a plurality (six in this embodiment) of fuel gas passages 11 (through holes) extending in the longitudinal direction are formed at predetermined intervals in the width direction. In the present embodiment, first recesses 12 are formed at a plurality of locations on the main surface of the support substrate 10, and each first recess 12 extends over the entire circumference of the bottom wall made of the material of the support substrate 10. It is a rectangular parallelepiped depression defined by circumferentially closed side walls (two side walls along the longitudinal direction and two side walls along the width direction) made of the material of the support substrate 10.

  The support substrate 10 is made of “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 FIG. 2, the entire fuel electrode current collector 21 is embedded (filled) in each first 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 second recess 21 a is formed on the upper surface (outer surface) of each fuel electrode current collector 21. As shown in FIG. 1B, each of the second recesses 21a has a bottom wall made of the material of the fuel electrode current collector 21, a side wall closed in the circumferential direction (two side walls along the longitudinal direction, and a width direction). A rectangular parallelepiped depression defined by two side walls). Of the side walls closed in the circumferential direction, two side walls along the longitudinal direction (x-axis direction) are made of the material of the support substrate 10, and the two side walls along the width direction (y-axis direction) are the anode current collector 21. Made of material.

The entire fuel electrode active portion 22 is embedded (filled) in each second recess 21a. Therefore,
Each fuel electrode active part 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. Two side surfaces and a bottom surface along the width direction (y-axis direction) of each anode active portion 22 are in contact with the anode current collecting portion 21 in the second recess 21a.

  A third recess 21b is formed in the upper surface (outer surface) of each fuel electrode current collector 21 except for the second recess 21a. Each of the third recesses 21b is defined by a bottom wall made of the material of the anode current collector 21 and side walls closed in the circumferential direction (two side walls along the longitudinal direction and two side walls along the width direction). It is a rectangular parallelepiped depression. Of the side walls closed in the circumferential direction, two side walls along the longitudinal direction (x-axis direction) are made of the material of the support substrate 10, and the two side walls along the width direction (y-axis direction) are the anode current collector 21. Made of material.

  An interconnector (conductive dense body) 30 is embedded (filled) in each third 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. Two side surfaces and a bottom surface along the width direction (y-axis direction) of each interconnector 30 are in contact with the fuel electrode current collector 21 in the third recess 21b.

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

The fuel electrode active part 22 may be composed of, for example, NiO (nickel oxide) and YSZ (yttria stabilized zirconia). Or you may be comprised 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 (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 first 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 oxidative ion conductivity relative to the total volume excluding the pore portion” in the anode active portion 22 is “the oxidative ion conductivity relative to the entire volume excluding the pore portion” in the anode current collecting portion 21. More than the volume fraction of the substance having

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

Each of the portions where the plurality of interconnectors 30 are formed on the outer peripheral surface extending in the longitudinal direction (the arrangement direction of the power generating element portions A) of the support substrate 10 in a state where the fuel electrode 20 is embedded in each of the first recesses 12. The entire surface excluding the central portion in the longitudinal direction is covered with the solid electrolyte membrane 40. The solid electrolyte membrane 40 is a fired body made of a dense material having ionic conductivity and not electron conductivity. The solid electrolyte membrane 40 can be made of, for example, YSZ (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 first 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. 2A, in this embodiment, the solid electrolyte membrane 40 has a longitudinal direction on the upper surface of the fuel electrode 20 (the fuel electrode current collector 21 + the fuel electrode active portion 22) and the upper surface of the interconnector 30. Both side ends and the main surface of the support substrate 10 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 as viewed from above is substantially the same rectangle as the fuel electrode active part 22, or the reaction prevention film 50 is slightly wider than 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 membrane 40 and the Sr in the air electrode 60 react with each other in the cell during cell production or in operation, and the solid electrolyte membrane 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). That is, on the upper surface of the support substrate 10, a plurality (four in this embodiment) of power generating element portions A are arranged at a predetermined interval in the longitudinal direction.

  Regarding the adjacent power generation element portions A and A, the air electrode 60 of the other power generation element portion A (on the left side in FIG. 2A) and one power generation element portion A (on the right side in FIG. 2A). The air electrode current collecting film 70, which is an air electrode current collector, is formed on the upper surfaces of the air electrode 60 and the interconnector 30 so as to straddle 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, it may be composed of LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite). 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, the air electrode 60 of the other power generation element part A (on the left side in FIG. 2A) for the adjacent power generation element parts A and A, One (on the right side in FIG. 2 (a)) the fuel electrode 20 (particularly the fuel electrode current collector 21) of the power generation element part A is electronically conductive, “air electrode current collector film 70 and interconnector 30”. ”Is electrically connected.

  As a result, a plurality (four in this embodiment) of power generating 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”.

  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. 3, the fuel gas (hydrogen gas or the like) flows through the fuel gas passage 11 of the support substrate 10 and the upper and lower surfaces of the support substrate 10 ( In particular, by exposing each air electrode current collector film 70) to “a 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 membrane 40 An electromotive force is generated by a difference in oxygen partial pressure generated between the two side surfaces. 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. 2A, the current flows as indicated by the arrows in the adjacent power generation element portions A and A. As a result, electric power is extracted from the entire cell (specifically, via the interconnector 30 of the power generating element portion A on the frontmost side and the air electrode 60 of the power generating element portion A on the farthest side in FIG. 3).

  And in this form, as shown to Fig.2 (a), the end surface and end part surface in the side of the interconnector 30 of the solid electrolyte membrane 40 of one electric power generation element part A are coat | covered with the covering sealing layer 71, and this covering seal | sticker Layer 71 is bonded to the surface of interconnector 30.

  That is, the solid electrolyte membrane 40 is extended from both sides of one and the other power generation element part A and laminated on both ends of the interconnector 30, and the air electrode current collector 70 is connected to the air electrode of the other power generation element part A. 60 extends from the surface to one power generation element portion A side and is laminated on the surface of the interconnector 30, and the end portion of the solid electrolyte membrane 40 extending from the one power generation element portion A is formed on the surface of the interconnector 30. The end surface and the end surface of the solid electrolyte membrane 40 on the surface of the interconnector 30 are covered with the covering seal layer 71.

  Further, the end surface and the end surface of the reaction preventing film 50 on the interconnector 30 side are also covered with the covering seal layer 71.

  Thereby, the leakage of gas from the interface between the solid electrolyte membrane 40 and the interconnector 30 and the end surface of the solid electrolyte membrane 40 can be suppressed, and the gas blocking performance can be improved.

That is, conventionally, an anode current collector 21 is embedded in the first recess 12 of the support substrate 10, and an anode active portion 22 is embedded in the second recess 21 a of the anode current collector 21. Since the interconnector 30 is embedded in the third recess 21b of the portion 21 and fired in this state to produce the solid oxide fuel cell, the support substrate material constituting the recesses 12, 21a, 21b, and the recess 12, 21 a, 21 b due to differences in firing shrinkage behavior, thermal expansion coefficient, etc., from the materials constituting the anode current collector 21, anode active portion 22, and interconnector 30 embedded in the anodes 21, 21 a, 21 b. A gap is formed between the wall surface forming the material and the material embedded in the recesses 12, 21a, 21b, and as a result, a crack occurs in the solid electrolyte membrane 40, or the solid electrolyte membrane 40 and the interconnect 30, the fuel gas flowing in the support substrate 10 leaks out of the support substrate 10, and the gas blocking performance between the fuel gas supplied to the fuel electrode 20 and the air supplied to the air electrode 60 decreases. There was a fear.

  On the other hand, in this embodiment, the end surface and the end surface on the interconnector 30 side of the solid electrolyte membrane 40 of one power generation element portion A are covered with the covering seal layer 71, and the covering seal layer 71 is Since it is bonded to the surface, separation between the solid electrolyte membrane 40 and the interconnector 30 can be suppressed, leakage of fuel gas from the interface between them can be suppressed, and the wall surfaces constituting the recesses 12, 21a, 21b Due to differences in firing shrinkage behavior, thermal expansion coefficient, etc. between the materials embedded in the recesses 12, 21a, 21b, gaps are formed between them, and cracks are formed on the end surface of the solid electrolyte membrane 40. Even if it occurs, since it is covered with the covering seal layer 71, leakage of the fuel gas from the end surface of the solid electrolyte membrane 40 can be suppressed, and the gas blocking performance can be improved.

  Further, since the end surface and the end surface of the reaction preventing film 50 on the interconnector 30 side are also covered with the covering seal layer 71, the reaction preventing film 50 can be prevented from being peeled off from the solid electrolyte film 40.

  The covering seal layer 71 is made of, for example, forsterite or glass.

  In FIG. 4, a dense insulating seal portion 78 is disposed around the interconnector 30, and the entire periphery of the outer peripheral edge of the insulating seal portion 78 is covered with the solid electrolyte membrane 40. In this embodiment, the end portion of the solid electrolyte membrane 40 is disposed on the upper surface of the insulating seal portion 78, and the end surface and the end portion surface of the solid electrolyte membrane 40 of one power generation element portion A on the interconnector 30 side are shown. Is covered with the covering seal layer 71, and the covering seal layer 71 is bonded to the surface of the insulating seal portion 78.

  That is, as shown in FIG. 4, an insulating seal portion 78 made of a material different from that of the interconnector 30 and the solid electrolyte membrane 40 is formed between the side wall of the third recess 21 b and the interconnector 30. The solid electrolyte membrane 40 is laminated on the insulating seal portion 78 and is not laminated on the interconnector 30. The difference from FIG. 2A is that the insulating seal portion 78 surrounds the periphery of the interconnector 30.

The insulating seal part 78 is a fired body made of a dense material having electrical insulation. The insulating seal part 78 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. Further, as trace components, transition metal oxides (for example, NiO, Mn ₃ O ₄ , Fe ₂ O ₃ , Cr ₂ O ₃ , CoO)
May be included.

These components may exist as oxides, and the above “(AE) ZrO ₃ , Mg
At least one selected from the group consisting of O, 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 “type of 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 insulating seal part 78 is 10 to 100 μm.

  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 surface of the interconnector and the inner surface of the solid electrolyte membrane, and the “gas seal function” is liable 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. That is, a decrease in the “gas seal function” can be suppressed.

  FIG. 5 shows a form in which one power generating element part A side of the air electrode current collector 70 is laminated on the surface of the covering seal layer 71 in the form shown in FIG.

  In this embodiment, even if the fuel electrode current collector 21 exists inside the solid electrolyte membrane 40 and the air electrode current collector 70 exists outside, the insulation between the solid electrolyte membrane 40 and the air electrode current collector membrane 70 is present. The non-ionic and non-conductive covering seal layer 71 is interposed, and the air current collecting film 70 is not laminated on the surface of the solid electrolyte film 40. Contrary to 2), a battery through which a current flows is not formed, and the power generation performance can be improved.

(Production method)
Next, an example of a manufacturing method of the “horizontal stripe type” cell shown in FIG. 1 will be briefly described with reference to FIGS. 6 to 7, “g” at the end of the reference numeral of each member indicates that the member is “before firing”.

  First, a support substrate molded body 10g having the shape shown in FIG. 6 is manufactured. The support substrate molded body 10g is produced 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, NiO + MgO). .

  Next, as shown in FIG. 7B, the molded body 21g of the fuel electrode current collector is embedded and formed in each first recess formed on the upper and lower surfaces of the molded body 10g of the support substrate. Next, a molded body 22g of the fuel electrode active part is embedded and formed in each second recess formed on the outer surface of the molded body 21g of each fuel electrode current collector. Further, the molded body 21g of each fuel electrode current collector and each fuel electrode active part 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). Then embed and form using printing methods.

Subsequently, the interconnector is molded in each third recess formed in the “surface portion excluding the portion where the molded body 22g of the fuel electrode active portion is embedded” on the outer surface of the molded body 21g of each fuel electrode current collector. Each body 30g is embedded and formed. The molded body 30g of each interconnector is embedded and formed 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, the plurality of interconnectors are formed on the outer peripheral surface extending in the longitudinal direction of the molded body 10g of the support substrate in which the plurality of molded fuel electrode bodies (21g + 22g) and the plurality of interconnector molded bodies 30g are embedded and formed. A molded membrane of a solid electrolyte membrane is formed on the entire surface excluding the central portion in the longitudinal direction of each portion where the molded body 30g is formed. The molded membrane of the solid electrolyte membrane is formed by 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), using a printing method, a dipping method, or the like.

  Next, a molded film of the reaction preventing film is formed on the outer surface of the portion of the solid electrolyte membrane that is in contact with the molded body of each fuel electrode. The molded film of each reaction prevention film is formed using a slurry obtained by adding a binder or the like to the powder of the material of the reaction prevention film 50 (for example, GDC), 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 at 1500 ° C. for 3 hours in air, for example. Thereby, the structure in a state where the air electrode 60 and the air electrode current collector 70 are not formed in the cell shown in FIGS.

  Thereafter, a slurry such as forsterite or glass is applied to the end surface and the end surface of the solid electrolyte membrane 40 on the surface of the interconnector 30 and heat-treated to form the covering seal layer 71. Further, the slurry is applied to the end surface and the end surface of the reaction preventing film 50 to form the covering seal layer 71.

  Next, an air electrode forming film is formed on the outer surface of each reaction preventing film 50. The molded film 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, for each pair of adjacent power generating element portions, the air electrode forming film, the interconnect film 30 of the other power generating element portion A and the interconnector 30 of one power generating element portion A are straddled. A molding film for the air electrode current collector is formed on the outer surface of the connector 30.

  The forming film of each air electrode current collector is formed by using a printing method or the like using a slurry obtained by adding a binder or the like to the powder of the material of the air electrode current collector 70 (for example, LSCF), for example. To do.

  And the support substrate 10 in the state in which the molded film is formed in this way is baked, for example, in air at 1050 ° C. for 3 hours. Thereby, the cell shown in FIG. 2 is obtained.

  In addition, when the firing temperature of the covering seal layer 71 is lower than the firing temperature of the air electrode 60 and the air electrode current collector 70, after forming the air electrode 60 and the air electrode current collector 70, the covering seal layer 71 is formed. Can be formed.

(Action / Effect)
As described above, in the “horizontal stripe” cell according to the embodiment of the present invention, the end surface and the end surface on the interconnector 30 side of the solid electrolyte membrane 40 of one power generation element portion A are covered with the covering seal layer 71. Since the covering seal layer 71 is bonded to the surface of the interconnector 30, the separation between the solid electrolyte membrane 40 and the interconnector 30 can be suppressed, and the leakage of fuel gas from the interface between them can be suppressed. In addition, even if a crack is generated on the end surface of the solid electrolyte membrane 40, it is covered with the coating seal layer 71, so that leakage of fuel gas from the end surface of the solid electrolyte membrane 40 can be suppressed, and gas blocking performance can be achieved. Can be improved.

  In addition, each of the plurality of first recesses 12 embedded in the upper and lower surfaces of the support substrate 10 for embedding the fuel electrode 20 (current collector 21) is made of the material of the support substrate 10 over the entire circumference. It has a side wall closed in the circumferential direction. In other words, a frame surrounding each first recess 12 is formed on the support substrate 10. Therefore, this structure is not easily deformed when the support substrate 10 receives an external force.

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

  Further, the interconnector 30 is embedded in a third recess 21b formed on the outer surface of the fuel electrode current collector 21, and as a result, two side surfaces along the width direction (y-axis direction) of the rectangular interconnector 30 are formed. And the bottom surface 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.

  In the above-described embodiment, the solid electrolyte membrane 40 includes the outer surface of the fuel electrode 20 (the current collector 21 + the active portion 22), both side ends 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.

  Moreover, in the said embodiment, although the whole interconnector 30 is embed | buried under each 3rd recessed part 21b, only a part of interconnector 30 is embed | buried in each 3rd recessed part 21b, and the remainder of the interconnector 30 is filled. The portion may protrude outside the third recess 21b (that is, protrude from the main surface of the support substrate 10).

  Further, in the above embodiment, a plurality of first recesses 12 are formed on each of the upper and lower surfaces of the flat support substrate 10 and a plurality of power generating element portions A are provided, but only one side of the support substrate 10 is provided. A plurality of first recesses 12 may be formed 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.

In addition, in the above embodiment, as shown in FIG. 1 (b), the recess 21 b formed on the outer surface of the fuel electrode current collector 21 has a bottom wall made of the material of the fuel electrode current collector 21, A rectangular parallelepiped shape defined by side walls closed in the circumferential direction (two side walls along the longitudinal direction made of the material of the support substrate 10 and two side walls along the width direction made of the material of the fuel electrode current collector 21). It is a depression. As a result, the two side surfaces and the bottom surface along the width direction of the interconnector 30 embedded in the third recess 21b are in contact with the fuel electrode current collector 21 in the recess 21b.

  On the other hand, as shown in FIG. 8, the third recess 21 b formed on the outer surface of the fuel electrode current collector 21 has a bottom wall made of the material of the fuel electrode current collector 21 and the fuel over the entire circumference. It may be a rectangular parallelepiped recess defined by circumferentially closed side walls (two side walls along the longitudinal direction and two side walls along the width direction) made of the material of the pole current collector 21.

DESCRIPTION OF SYMBOLS 10 ... Support substrate 11 ... Fuel gas flow path 12 ... 1st recessed part 20 ... Fuel electrode 21 ... Fuel electrode current collection part 21a ... 2nd recessed part 21b ... 3rd recessed part 22 ... Fuel electrode active part 30 ... Interconnector (conductive dense body)
60 ... Air electrode 70 ... Air electrode current collector 71 ... Coating seal layer 78 ... Insulating seal part A ... Power generation element

Claims (3)

A flat porous support substrate having a gas flow path formed therein;
A plurality of power generation element portions each provided at a plurality of locations separated from each other on the main surface of the support substrate, and a stack of at least a fuel electrode, a solid electrolyte, and an air electrode;
Each provided between the adjacent power generation element parts, and having an electrical connection part for electrically connecting the fuel electrode of one of the power generation element parts and the air electrode of the other power generation element part,
The fuel electrode comprises a fuel electrode current collector and a fuel electrode active part having a higher content ratio of a substance having ion conductivity than the fuel electrode current collector,
A first recess having a bottom wall and a side wall closed in the circumferential direction is provided at each of the plurality of locations on the main surface of the support substrate, and the fuel electrode current collector is embedded in each first recess.
The anode active part is embedded in a second recess formed on the outer surface of the anode current collector embedded in the first recess;
Conductivity that constitutes a part of the electrical connection portion in the third recess formed on the outer surface of the fuel electrode current collector embedded in the first recess at a position different from the position where the second recess is formed. The dense and dense body is buried,
Solid electrolytes stacked on the fuel electrode active portion are extended from both sides of the one and the other power generation element portions and provided at both ends of the conductive dense body or both ends of the conductive dense body. Further, an air current collector that is stacked on both ends of the insulating seal part and that constitutes a part of the electrical connection part is disposed on the one power generation element part side from the air electrode surface of the other power generation element part. And the end surface and the end surface of the solid electrolyte of the one power generating element portion on the conductive dense body side are covered with a covering seal layer, A solid oxide fuel cell, wherein a covering seal layer is bonded to a surface of the conductive dense body or the insulating seal portion.   A reaction preventing layer is interposed between the solid electrolyte and the air electrode current collecting layer, and an end surface and an end surface of the reaction preventing layer on the conductive dense body side are covered with the covering seal layer. The solid oxide fuel cell according to claim 1, wherein:   The air electrode current collector is extended to the one power generation element part side of the conductive dense body and laminated on the surface of the covering seal layer. The solid oxide fuel cell as described.

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