JP2013239330A - Solid oxide fuel cell and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide fuel battery which can both prevent the spread of chromium from an interconnector and secure a gas passage in the interconnector and a manufacturing method therefor.SOLUTION: A solid oxide fuel battery comprises: a fuel battery cell body which includes an air electrode layer, a solid electrolyte layer and a fuel electrode layer and has power generation function; and an interconnector which includes a flat shaped flat portion and a plurality of convex portions protruding from a plane on one side of the flat portion and electrically connected to an electrode layer on one side of the air electrode layer and the fuel electrode layer, part of which being pushed into the electrode layer on the one side, and which is formed from a metallic material. The solid oxide fuel battery further includes a coating layer covering the top faces and at least part of the side faces of the convex portions and not covering at least part of the flat portion.

Description

  The present invention relates to a solid oxide fuel cell having a solid electrolyte layer and a method for manufacturing the same.

As a fuel cell, a solid oxide fuel cell (hereinafter also referred to as “SOFC”) using a solid electrolyte (solid oxide) is known. This SOFC is composed of, for example, a fuel cell body (stacked body) provided with a fuel electrode and an air electrode on each surface of a plate-like solid electrolyte layer. Electric power is generated by supplying fuel gas to the fuel electrode, supplying air to the air electrode, and chemically reacting fuel (fuel gas) and oxygen in the air (oxidant gas) via the solid electrolyte layer. To do.
A current collector (interconnector) is electrically connected to the fuel cell body, and the electric power generated from the fuel cell body is output to the outside.

  Here, a technique for ensuring the contact area between the fuel cell body and the current collector is disclosed (see Patent Document 1). That is, the plurality of convex portions provided on the current collector are inserted into the crushing deformation portions formed in the electrode layer (fuel cell main body). Since the convex portion of the current collector is inserted into the electrode layer, the contact area between the fuel cell body and the current collector is ensured.

  A technique for preventing diffusion of chromium from a separator for separating fuel gas and oxidant gas has been disclosed (see Patent Document 2). That is, a surface protective layer made of an oxide that easily reacts with chromium is formed on the surface of the oxidant gas passage of the separator. The oxide of the surface protective layer reacts with chromium to prevent the diffusion of chromium.

JP 2010-272499 A JP-A-7-153469

Here, a metal containing chromium is used for the interconnector in terms of conductivity and heat resistance. If this chromium diffuses into the fuel cell body, the function of the fuel cell body may be degraded.
By applying the technique of Patent Document 1, it is possible to improve the reliability of electrical connection between the fuel cell body and the interconnector, but it is difficult to prevent diffusion of chromium from the interconnector.
Even if the technique of Patent Document 2 is applied, the surface protective layer formed on the interconnector may narrow the oxidant gas passage, which may make it difficult to secure the gas passage.

  The present invention has been made to solve the above-described problems, and is a solid oxide fuel cell that achieves both prevention of diffusion of chromium from an interconnector and securing of a gas flow path on the interconnector. And it aims at providing the manufacturing method.

A. A solid oxide fuel cell according to an aspect of the present invention includes an air electrode layer, a solid electrolyte layer, and a fuel electrode layer, and has a power generation function, a fuel cell body, a flat flat portion, and the flat portion. A plurality of protrusions protruding from one surface of the portion and electrically connected to one of the air electrode layer or one of the fuel electrode layers, a portion of which is pushed into the one electrode layer, A solid oxide fuel cell comprising: an interconnector formed of a metal material, wherein the coating covers an upper surface and at least a part of a side surface of the convex part and does not cover at least a part of the flat part Further comprising a layer,
It is characterized by that.

  In this solid oxide fuel cell, the interconnector has “a plurality of protrusions electrically connected to the air electrode layer or one of the fuel electrode layers and part of which is pushed into the one electrode layer. By having the “part”, the reliability of electrical connection between the interconnector and one of the electrode layers is ensured. In addition, “a covering layer that covers the upper surface and at least a part of the side surface of the convex part and does not cover at least a part of the flat part” is provided. That is, since the coating layer does not cover at least a part of the flat portion, a gas flow path on the flat portion is ensured. As a result, it is possible to achieve both the reliability of the electrical connection and the securing of the gas flow path.

(1) It is preferable that the thickness of the coating layer is 0.001 mm or more and less than (0.5 × L) (L: distance between the plurality of convex portions).
If the thickness of the coating layer is less than 0.001 mm, the reliability of electrical connection may not be ensured. Further, if the thickness of the coating layer is (0.5 × L) or more, the plurality of convex portions are blocked by the coating layer, and it is difficult to secure a gas flow path on the flat portion.

(2) It is preferable that the curvature radius R2 of the edge part of the coating layer corresponding to the tip side edge part is larger than the curvature radius R1 of the tip side edge part of the convex part.
By rounding the shape of the edge part of the coating layer rather than the edge part on the tip side of the convex part, the stress concentration when the convex part is pushed into one electrode layer is alleviated and cracking of one electrode layer is prevented it can.

(3) The coating layer may be formed by printing.
The coating layer can be easily formed using printing. For this printing, mask printing having a larger opening than the convex portion, screen printing, tamping printing, or the like can be used.

(4) The coating layer may contain any of Ag, AgPd alloy, spinel material, and perovskite material. These materials have the function of preventing the diffusion of chromium.

B. A method for manufacturing a solid oxide fuel cell includes: a flat portion having a flat shape; and a plurality of electrodes that protrude from one surface of the flat portion and are electrically connected to one electrode layer of the air electrode layer or the fuel electrode layer. And a step of preparing an interconnector formed of a metal material, and a covering layer that covers an upper surface and at least a part of a side surface of the convex part and does not cover at least a part of the flat part And a step of forming by printing.

  Since the interconnector has “a plurality of convex portions electrically connected to one electrode layer”, the reliability of electrical connection is improved, and “the upper surface and at least a part of the side surfaces of the convex portions are covered, By forming a coating layer that does not cover at least a part of the flat portion by printing, a gas flow path can be secured. That is, it is possible to manufacture a solid oxide fuel cell capable of satisfying both the reliability of electrical connection and the securing of a gas flow path.

(1) The step of forming the coating layer by printing includes a step of applying the paste to the plurality of convex portions by extruding a paste of a material constituting the coating layer from a plurality of openings of the mask. Also good.
The coating layer can be efficiently formed by extruding the paste from a plurality of openings of the mask and applying the paste to the plurality of convex portions.

(2) The plurality of openings may be arranged corresponding to the plurality of convex portions and have a diameter larger than those convex portions.
By extruding the paste from a plurality of openings arranged corresponding to the plurality of protrusions and having a diameter larger than these protrusions, the coating layer can be efficiently applied not only to the tips of the protrusions but also to the side surfaces thereof. Can be formed.

(3) The step of forming the coating layer by printing includes a step of applying the paste to the plurality of convex portions by pressing a plate-like member to which the paste of the material constituting the coating layer is applied. May be.
By pressing the plate-like member to which the paste is applied, this paste can be applied to a plurality of convex portions, and the coating layer can be formed efficiently.

(4) The paste may contain any of Ag, AgPd alloy, spinel material, and perovskite material. These materials have the function of preventing the diffusion of chromium.

(5) A step of preparing a fuel cell body having an air electrode layer, a solid electrolyte layer, and a fuel electrode layer and having a power generation function; and within one of the air electrode layer and the fuel electrode layer, And a step of pushing in the plurality of convex portions of the interconnector on which the coating layer is formed.
By "pressing the plurality of protrusions of the interconnector on which the coating layer is formed in one electrode layer", the reliability of electrical connection between the interconnector and one electrode layer is ensured.

  ADVANTAGE OF THE INVENTION According to this invention, the solid oxide fuel cell which aimed at the diffusion prevention of chromium from an interconnector, and ensuring the flow path of the gas on an interconnector, and its manufacturing method can be provided.

1 is a perspective view illustrating a solid oxide fuel cell according to an embodiment of the present invention. It is sectional drawing showing the state which cut | disconnected the solid oxide fuel cell in the X-axis direction of FIG. It is a side view showing the state where the fuel cell body and the interconnector face each other. It is an enlarged side view showing the state where the interconnector was pushed into the fuel cell body. It is a front view of an interconnector. It is the enlarged view to which a part of FIG. 5 was expanded. It is a flowchart showing the manufacturing process of a solid oxide fuel cell. In the solid oxide fuel cell concerning the comparative example 1, it is an enlarged side view showing the state by which the interconnector was pushed in the fuel cell main body. In the solid oxide fuel cell concerning the comparative example 2, it is an enlarged side view showing the state by which the interconnector was pushed in the fuel cell main body. FIG. 6 is an enlarged side view showing a state in which an interconnector is pushed into a fuel cell body in a solid oxide fuel cell according to Modification 1. FIG. 9 is an enlarged side view showing a state where an interconnector is pushed into a fuel cell body in a solid oxide fuel cell according to Modification 2. FIG. 9 is an enlarged side view showing a state where an interconnector is pushed into a fuel cell body in a solid oxide fuel cell according to Modification 3.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Embodiment)
FIG. 1 is a perspective view showing a solid oxide fuel cell (solid oxide fuel cell stack) 10 according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a state where the solid oxide fuel cell 10 is cut in the X-axis direction of FIG. FIG. 3 is a side view showing a state in which the fuel cell body 110 and the interconnector 130 face each other. FIG. 4 is an enlarged side view showing a state where the interconnector 130 is pushed into the fuel cell main body 110. FIG. 5 is a front view of the interconnector 130. FIG. 6 is an enlarged view of a part of FIG.

  The solid oxide fuel cell 10 has a substantially rectangular parallelepiped shape, and includes an upper surface 11, a bottom surface 12, an oxidant gas flow channel 21, 23, fuel gas flow channels 22 and 24, and through holes 25 to 28, and a connecting member ( Fasteners 41 to 48 and nuts 51 to 58) are attached.

  Members 61, 63, 62, 64 are arranged on the upper surface 11 corresponding to the oxidant gas passages 21, 23 and the fuel gas passages 22, 24. The members 61, 63, 62, and 64 have through holes that communicate with the oxidant gas channels 21 and 23 and the fuel gas channels 22 and 24, respectively. Bolts 41 to 44 are inserted into members 61 to 64, and nuts 51 to 54 are screwed.

  Since the diameter of the shafts of the bolts 41 to 44 is smaller than the diameter of the through holes of the members 61 to 64, gas (oxidant gas (air), power generation) is formed between the through holes of the members 61 to 64 and the shafts of the bolts 41 to 44. The remaining fuel gas, the remaining oxidant gas, and the fuel gas after power generation) pass through. That is, oxidant gas (air) and fuel gas flow into the solid oxide fuel cell 10 from the members 61 and 62, respectively. The remaining oxidant gas (air) after power generation and the remaining fuel gas after power generation flow out from the solid oxide fuel cell 10 to the members 63 and 64.

  The solid oxide fuel cell 10 is configured by laminating a plurality of flat solid oxide fuel cells 100 as power generation units. A plurality of solid oxide fuel cells 100 (100 (1) to 100 (3)) are electrically connected in series. For ease of viewing, the number of solid oxide fuel cells 100 in FIG. In many cases, more (for example, 20) solid oxide fuel cells 100 are stacked to form the solid oxide fuel cell 10.

  The solid oxide fuel cell 100 has a rectangular parallelepiped shape, and includes a stacked body (fuel cell main body) 110 in which a fuel electrode layer 111, a solid electrolyte layer 112, and an air electrode layer 113 are sequentially stacked.

  The fuel electrode layer 111 is in contact with a fuel gas (for example, hydrogen) serving as a reducing agent and functions as a negative electrode in the solid oxide fuel cell.

Examples of the material of the fuel electrode layer 111 include ZrO ₂ ceramics such as zirconia stabilized by at least one of metals such as Ni and Fe and rare earth elements such as Sc and Y, CeO ₂ ceramics, and the like. Examples thereof include a mixture with at least one of ceramics such as manganese oxide. Moreover, metals, such as Pt, Au, Ag, Pd, Ir, Ru, Rh, Ni, and Fe, are mentioned.

These metals may be used alone or in an alloy of two or more metals. Further, a mixture (including cermet) of these metals and / or alloys and at least one of each of the above ceramics may be mentioned.
Moreover, the mixture of the oxide of metals, such as Ni and Fe, and at least 1 type of each of the said ceramic etc. are mentioned.

  The solid electrolyte layer 112 has ion conductivity capable of moving a part of one of the fuel gas introduced into the fuel electrode or the oxidant gas introduced into the air electrode during operation of the battery as ions. Examples of the ions include oxygen ions and hydrogen ions.

Examples of the material for the solid electrolyte layer include ZrO ₂ ceramics, LaGaO ₃ ceramics, BaCeO ₃ ceramics, SrCeO ₃ ceramics, SrZrO ₃ ceramics, and CaZrO ₃ ceramics.

  The air electrode layer 113 is in contact with an oxidant gas (for example, air (specifically, oxygen in the air)) serving as an oxidant, and functions as a positive electrode in the solid oxide fuel cell.

  As a material of the air electrode layer 113, for example, various metals, metal oxides, metal double oxides, and the like can be used. Further, as a material for the air electrode layer 113, a mixture thereof (for example, a cermet of a metal material and a ceramic material (oxide or the like)) can be used.

Examples of the metal include metals such as Pt, Au, Ag, Pd, Ir, Ru, and Rh, or alloys containing two or more metals. Examples of the metal oxide include oxides such as La, Sr, Ce, Co, Mn, and Fe (La ₂ O ₃ , SrO, Ce ₂ O ₃ , Co ₂ O ₃ , MnO _2, FeO, and the like). As the double oxide, a double oxide containing at least La, Pr, Sm, Sr, Ba, Co, Fe, Mn, etc. (La _1-x Sr _x CoO ₃ -based double oxide, La _1-x Sr _x FeO ₃ -based double oxide, La _1-x Sr _x Co _1-y Fe _y O ₃ -based double oxide, La _1-x Sr _x MnO ₃ -based double oxide, Pr _1-x Ba _x CoO ₃ -based double oxide Oxides (LSCF (lanthanum strontium cobalt iron oxide)) and Sm _1-x Sr _x CoO ₃ -based double oxides).

  The air electrode layer 113 is divided into a first electrode layer 113a having a relatively high density or particle bond strength and a second electrode layer 113b having a relatively low density or particle bond strength. For example, the first electrode layer 113a uses a mixture of LSCF (lanthanum strontium cobalt ferrite) and GDC (Gadolinium doped Ceria), and the second electrode layer 113b uses only LSCF. Can be formed. The density of the first electrode layer 113a or the bond strength of the particles is greater than that of the second electrode layer 113b. As a result, the hardness of the second electrode layer 113b is smaller than the hardness of the first electrode layer 113a.

  The first and second electrode layers 113a and 113b are formed by, for example, printing and sintering a powder material paste constituting the first electrode layer 113a, and then applying the powder material paste constituting the second electrode layer 113b to the first electrode layer 113a. The electrode layer 113a can be formed by printing and sintering.

  At this time, the particle size of the powder material of the first electrode layer 113a is made smaller than the particle size of the powder material of the second electrode layer 113b before the sintering. Accordingly, the degree of sintering progress of the first electrode layer 113a is larger than the degree of sintering progress of the second electrode layer 113b. As a result, the density of the first electrode layer 113a after sintering or the bond strength of the particles is larger than that of the second electrode layer 113b.

  As shown in FIG. 4, a convex portion 133 of an interconnector 130 described later is pushed into the second electrode layer 113b. The region having a predetermined thickness in the Z direction of the second electrode layer 113b is crushed and deformed, so that the protrusion 133 can be pushed in. As a result, the contact area between the second electrode layer 113b (the air electrode layer 113 and thus the fuel cell body 110) and the interconnector 130 is increased, and the reliability of the electrical connection is improved.

In the present embodiment, a so-called support membrane type solid oxide fuel cell 100 in which the fuel electrode layer 111 serves as a support base is taken as an example, but the present invention is not limited thereto.
In addition, a rectangular frame 150 is provided around the side of the laminated body 110, and an interconnector 130 and a current collector 140 are provided in the vertical direction of the laminated body 110.

  The frame 150 includes insulating frames 151 and 152 made of mica (mica), and metal frames 153 and 154 made of, for example, SUS430, and an in-cell separator 155 disposed therebetween.

  The in-cell separator 155 is joined over the entire circumference on the outer circumference of the upper surface of the solid electrolyte layer 112. The internal separator 155 separates the space inside the solid oxide fuel cell 100 into a fuel chamber 115 to which fuel gas is supplied and an air chamber 116 to which oxidant gas is supplied. Fuel gas flows in the Y direction in the fuel chamber 115. Oxidant gas flows in the X direction in the air chamber 116.

  The frame 150 is provided with oxidant gas passages 21, 23 and fuel gas passages 22, 24 penetrating the frame 150 in the vertical direction in FIG.

  The interconnector 130 is provided in contact with the air electrode layer 113 so as to obtain electrical conduction. The interconnector 130 has an outer peripheral part 131, a flat part 132, a convex part 133, and a coating layer 134. Among these, the outer peripheral part 131, the flat part 132, and the convex part 133 can be comprised integrally from a metal material.

  Examples of the metal material include heat-resistant alloys having conductivity and heat resistance, such as stainless steel, nickel-base alloy, and chromium-base alloy. The same applies to the metal frame described later.

  Specifically, examples of the stainless steel include ferritic stainless steel, martensitic stainless steel, and austenitic stainless steel. Examples of ferritic stainless steel include SUS430, SUS434, SUS405, and SUS444. Examples of martensitic stainless steel include SUS403, SUS410, and SUS431. Examples of austenitic stainless steel include SUS201, SUS301, and SUS305.

Further, examples of the nickel-based alloy include Inconel 600, Inconel 718, Incoloy 802, and the like. Examples of the chromium-based alloy include Ducrloy CRF (94Cr5Fe1Y ₂ O ₃ ). Moreover, Crofer22 alloy, ZMG232L, etc. are also mentioned.

  These metal materials (heat-resistant alloys such as stainless steel, nickel-base alloys, and chromium-base alloys) contain chromium (Cr). When this chromium diffuses into the air electrode layer 113, the function of the air electrode layer 113 may be deteriorated. In order to prevent this diffusion of chromium, the covering layer 134 is disposed on the convex portion 133.

  The outer peripheral portion 131 is disposed on the outer periphery of the interconnector 130. The outer peripheral portion 131 is provided with oxidant gas passages 21 and 23 in the X direction, and the fuel gas passages 22 and 24 are provided in the Y direction. Bolts 45 to 48 pass through the outer peripheral portion 131. Through holes 25 to 28 are provided.

  The flat portion 132 is a rectangular flat region disposed in the outer peripheral portion 131. The flat portion 132 and the outer peripheral portion 131 constitute one plane. That is, the flat portion 132 and the outer peripheral portion 131 are not clearly divided. For this reason, the boundary between the outer peripheral portion 131 and the flat portion 132 is indicated by a broken line.

The convex portion 133 is a dome-shaped region that protrudes from the flat portion 132 and whose tip contacts the surface of the air electrode layer 113.
As shown in FIGS. 5 and 6, the protrusions 133 are arranged at intervals (distances) Lx and Ly in the X and Y directions, respectively. The oxidant gas flows in the X direction through the interval Ly of the convex 133, and the oxidant gas flow path in the X direction in which the oxidant gas flow paths 21 and 23 are disposed is secured. When viewed on the XY plane, the convex 133 has a substantially rectangular shape having a long side in the X direction in which the oxidizing gas flows.

  As described above, the tip of the convex portion 133 is pushed into the second electrode layer 113b. By pressing the interconnector 130 toward the second electrode layer 113b in a state where the front end surface of the convex portion 133 and the upper surface of the second electrode layer 113b are overlapped, stress concentration occurs in the second electrode layer 113b. A part is brittle fractured, and the convex 133 is pushed in at a predetermined depth. Thereby, the interconnector 130 is joined to the air electrode layer 113 via the convex part 133 and the coating layer 134.

  Since the plurality of convex portions 133 are pushed into the air electrode layer 113, for example, when the air electrode layer 113 is warped or undulated, and the facing surfaces of the interconnector 130 and the air electrode layer 113 are difficult to be parallel to each other. However, the contact area between the air electrode layer 113 and the interconnector 130 is ensured, and the contact resistance is reduced.

  In the present embodiment, the interconnector 130 has a coating layer 134. The covering layer 134 suppresses diffusion of chromium from the interconnector 130 to the air electrode layer 113. As described above, the metal material of the interconnector 130 contains chromium. When this chromium diffuses into the air electrode layer 113, the function of the air electrode layer 113 may be deteriorated. The covering layer 134 electrically connects the interconnector 130 and the air electrode layer 113.

Thus, the constituent material of the coating layer 134 preferably has both suppression of chromium diffusion and electrical conductivity. As this constituent material, metal material (for example, Ag, AgPd alloy), metal (for example, noble metal (Ag, AgPd alloy, Pt)) and oxide (for example, (MnCo) ₃ O ₄ , (CuMn) ₃ O _4, etc.) of spinel type material, LSM: can select a mixed material of (lanthanum strontium manganite, lanthanum strontium manganite _{((La 1-x Sr x} ) y MnO 3) perovskite material, etc.).

  Metal materials such as Ag and AgPd alloys have both suppression of chromium diffusion and electrical conductivity. For this reason, these metal materials can be used as the constituent material of the coating layer 134.

  Spinel-based materials and perovskite-based materials (generally oxides) have a great ability to suppress the diffusion of chromium because they easily react with chromium. On the other hand, oxides generally have poor electrical conductivity. For this reason, it is conceivable that spinel materials, perovskite materials, etc. (oxides) and metals are mixed to form a constituent material of the coating layer 134 to achieve both suppression of chromium diffusion and electrical conductivity.

As the perovskite oxide, an oxide of at least one element or two or more elements selected from Ca, Sr, Ba, Y, La, and Ce (for example, La ₂ O ₃ , CaO, and SrO) can be considered. These oxides react with chromium to produce stable perovskite oxides (for example, LaCrO ₃ , CaCrO ₃ , SrCrO ₃ ). As a result, the diffusion of chromium from the interconnector 130 to the air electrode layer 113 is suppressed.

  As shown in FIG. 4, the covering layer 134 covers the bottom surface (upper surface) and the lower side surface of FIG. 4 (Z-axis negative direction), and the upper side surface of FIG. 4 (Z-axis positive direction) and the flat portion 132. Is not covered.

  It is important that the covering layer 134 covers the portion of the interconnector 130 that is pushed into the air electrode layer 113 (the bottom surface (upper surface) of the convex portion 133 and the side surface in the lower side of FIG. 4 (Z-axis negative direction)). This is to prevent direct diffusion of chromium from the interconnector 130 to the air electrode layer 113. On the other hand, in the portion that is not pushed into the air electrode layer 113 (the side surface in the upper part of FIG. 4 (Z-axis positive direction) and the flat portion 132), direct diffusion of chromium from the interconnector 130 to the air electrode layer 113 does not occur. Therefore, the necessity for disposing the coating layer 134 is poor. However, it is preferable that the coating layer 134 covers the convex portion 133 beyond the boundary between the convex portion 133 and the air electrode layer 113.

When the distance (interval) between the convex portions 133 is L, the thickness d of the coating layer 134 is preferably 0.001 mm or more and less than (0.5 × L) (see FIG. 4).
If the thickness of the coating layer 134 is less than 0.001 mm, the reliability of electrical connection may not be ensured. If the thickness d of the coating layer 134 is (0.5 × L) or more, the plurality of convex portions 133 are blocked by the coating layer 134, and it is difficult to secure a gas flow path on the flat portion 132. It becomes. Here, the distance L corresponds to the interval (distance) Ly. This is because the oxidant gas flows in the X direction between the convex portions 133 due to the interval Ly as described above.

The curvature radius R2 of the edge part of the coating layer 134 corresponding to this front edge part is larger than the curvature radius R1 of the front edge part of the convex part 133.
By rounding the shape of the edge portion of the covering layer 134 rather than the edge portion on the front end side of the convex portion 133, stress concentration when the convex portion 133 is pushed into the air electrode layer 113 is alleviated, and the air electrode layer 113 Breaking can be prevented. For example, by forming the coating layer 134 by printing, the shape of the edge portion of the coating layer 134 can be rounded more than the tip side edge portion of the convex portion 133.

  The interconnectors 130 (2) and 130 (3) are shared by the solid oxide fuel cells 100 (1) and 100 (2) and the solid oxide fuel cells 100 (2) and 100 (3), respectively. The

  In addition, the fuel electrode layer 111 of the solid oxide fuel cell 100 (2) is electrically connected to the air electrode layer 113 of the solid oxide fuel cell 100 (3) by the current collector 140 and the interconnector 130. Is done. The air electrode layer 113 of the solid oxide fuel cell 100 (2) is electrically connected to the fuel electrode layer 111 of the solid oxide fuel cell 100 (1) by the interconnector 130 and the current collector 140. ing. Even when the number of solid oxide fuel cells 100 is four or more, the connection relationship is the same except for the uppermost and lowermost solid oxide fuel cells 100.

  The current collector 140 can be made of a metal such as nickel (Ni).

  The air electrode layer 113 of the uppermost solid oxide fuel cell 100 (1) is formed on the metal end plate 121 serving as the positive electrode, and the fuel electrode layer 111 of the lowermost solid oxide fuel cell 100 (3) is formed. , And are electrically connected to the metal end plate 122 serving as a negative electrode.

(Manufacture of solid oxide fuel cell 10)
FIG. 7 is a flowchart showing the manufacturing process of the solid oxide fuel cell 10. The solid oxide fuel cell 10 can be manufactured by the following procedure.

(1) Formation of interconnector 130 main body (outer peripheral part 131, flat part 132, convex part 133) (step S11)
An interconnector 130 body having an outer peripheral portion 131, a flat portion 132, and a convex portion 133 is formed. For example, the convex 133 can be formed by processing a metal plate by pressing, etching, or the like.

(2) Formation of coating layer 134 on convex portion 133 of interconnector 130 (step S12)
A coating layer 134 is formed on the convex portion 133. Printing can be used for this formation. The coating layer 134 can be easily formed using printing. For this printing, a mask having an opening larger than the convex portion 133 can be used. Further, screen printing, tamping printing, or the like may be used.

  When the coating layer 134 is printed using a mask having an opening, the paste can be applied to the convex portion 133 by extruding a paste of a material constituting the coating layer 134 from a plurality of openings of the mask.

  Here, the openings of the mask may be arranged corresponding to the convex portions 133 and have a diameter larger than those of the convex portions 133. Since the opening of the mask has a diameter larger than that of the convex portion 133, formation of the coating layer 134 on the side surface of the convex portion 133 is facilitated.

  A plate-like member may be used in place of the mask having an opening. The paste can be applied to the convex portion 133 by pressing a plate-like member to which the material paste constituting the coating layer 134 is applied.

(3) Lamination of current collector 140, fuel cell body 110, and interconnector 130 (step S13)
The current collector 140, the fuel cell body 110, and the interconnector 130 are stacked. Here, the current collector 140 can be formed by sequentially printing and baking the materials constituting the fuel electrode layer 111, the solid electrolyte layer 112, and the air electrode layer 113, respectively. This firing may be performed in each layer of the fuel electrode layer 111, the solid electrolyte layer 112, and the air electrode layer 113, or may be performed collectively in a plurality of layers.

  As described above, the air electrode layer 113 is divided into the first electrode layer 113a having a relatively high density or particle bond strength and the second electrode layer 113b having a relatively low density or particle bond strength. Powder materials with different particle sizes are used.

(4) Pressure application by press (step S14)
The stacked current collector 140, fuel cell body 110, and interconnector 130 are pressurized with a press or the like. By this pressurization, the convex portion 133 of the interconnector 130 is pushed into the air electrode layer 113. That is, the stress is concentrated on a part of the second electrode layer 113b by the convex part 133, a part thereof is brittlely broken, and the convex part 133 is pushed in. Thereby, the interconnector 130 is joined to the air electrode layer 113 via the convex part 133 and the coating layer 134.

(Comparative Example 1)
A solid oxide fuel cell 10x1 according to Comparative Example 1 will be described. FIG. 8A is an enlarged side view showing a state in which the interconnector 130x1 is pushed into the fuel cell body 110 in the solid oxide fuel cell 10x1.

  The interconnector 130x1 has a flat portion 132, a convex portion 133, and a covering layer 134x. The covering layer 134x covers the entire surface of the convex portion 133 (the bottom surface and the side surface) and the entire surface of the flat portion 132. For this reason, between the convex parts 133 is narrowed, and oxidant gas becomes difficult to flow.

(Comparative Example 2)
A solid oxide fuel cell 10x2 according to Comparative Example 2 will be described. FIG. 8B is an enlarged side view showing a state in which the interconnector 130x2 is pushed into the fuel cell main body 110 in the solid oxide fuel cell 10x2.

  The interconnector 130x2 has a flat portion 132 and a convex portion 133, and does not have a coating layer 134. For this reason, the interconnector 130x2 and the air electrode layer 113 are in direct contact, and it becomes difficult to prevent diffusion of chromium from the interconnector 130x2 to the air electrode layer 113.

(Modification 1)
A solid oxide fuel cell 10a according to Modification 1 will be described. FIG. 9 is an enlarged side view showing a state in which the interconnector 130a is pushed into the fuel cell main body 110 in the solid oxide fuel cell 10a.

  The interconnector 130a has a flat portion 132, a convex portion 133, and a covering layer 134a. The covering layer 134a is disposed on the bottom surface (upper surface) of the convex portion 133 and is not disposed on the side surface thereof. Even in this case, the direct contact between the interconnector 130a and the air electrode layer 113 is prevented by the coating layer 134a, and diffusion of chromium from the interconnector 130a to the air electrode layer 113 is prevented.

(Modification 2)
A solid oxide fuel cell 10b according to Modification 2 will be described. FIG. 10 is an enlarged side view showing a state where the interconnector 130b is pushed into the fuel cell body 110 in the solid oxide fuel cell 10b.

  The interconnector 130b has a flat portion 132, a convex portion 133, and a coating layer 134b. The covering layer 134b is disposed on the entire surface (the bottom surface (upper surface) and the side surface) of the convex portion 133 and is not disposed on the convex portion 133. Even in this case, since the coating layer 134 b is not disposed on the flat portion 132, it is possible to secure an oxidant gas flow path between the convex portions 133.

(Modification 3)
A solid oxide fuel cell 10c according to Modification 3 will be described. FIG. 11 is an enlarged side view showing a state in which the interconnector 130c is pushed into the fuel cell body 110 in the solid oxide fuel cell 10c.

  The interconnector 130c has a flat portion 132, a convex portion 133c, and a covering layer 134c. The convex portion 133c becomes larger as it goes downward (toward the tip). Thus, even if the shape of the convex portion 133c is different, diffusion of chromium from the interconnector 130c to the air electrode layer 113 is prevented by having the coating layer 134c. Further, it is possible to secure a flow path for the oxidant gas between the convex portions 133c.

(Other embodiments)
Embodiments of the present invention are not limited to the above-described embodiments, and can be expanded and modified. The expanded and modified embodiments are also included in the technical scope of the present invention.

  In the above embodiment, the interconnector 130 having the convex portion 133 and the covering layer 134 is disposed on the air electrode layer 113 side. Instead, the interconnector 130 having the convex portion 133 and the coating layer 134 may be disposed on the fuel electrode layer 111 side.

  In this case, the fuel electrode layer 111 is divided into a lower layer having a relatively high density or particle bond strength and an upper layer having a relatively low density or particle bond strength so that the protrusion 133 can be easily pushed. Is preferred. This is because the protrusion 133 can be easily pushed into the fuel electrode layer 111 (upper layer).

  Further, when the hardness of the first electrode layer 113a and the second electrode layer 113b is made different, in the above embodiment, the same powder material is used and the particle diameter of the powder material is made different. For example, materials having different hardnesses may be used in advance.

DESCRIPTION OF SYMBOLS 10 Solid oxide fuel cell 11 Upper surface 21, 23 Oxidant gas flow path 22, 24 Fuel gas flow path 25-28 Through-hole 41-48 Bolt 51-58 Nut 61-64 Member 100 Solid oxide fuel cell 110 Laminated body 111 Fuel electrode layer 112 Solid electrolyte layer 113 Air electrode layers 113a and 113b First and second electrode layers 115 Fuel chamber 116 Air chamber 121 Metal end plate 122 Metal end plate 130 Interconnector 131 Outer peripheral portion 132 Flat portion 133 Convex Part 134 coating layer 140 current collector 150 frame 151, 152 insulating frame 153, 154 metal frame 155 separator in cell

Claims (11)

A fuel cell body having an air electrode layer, a solid electrolyte layer, and a fuel electrode layer, and having a power generation function;
A flat portion having a flat shape, protruding from one surface of the flat portion and electrically connected to one of the air electrode layer or the fuel electrode layer, a part of which is pushed into the one electrode layer An interconnector having a plurality of protrusions and formed of a metal material;
In a solid oxide fuel cell comprising:
A covering layer that covers the upper surface and at least part of the side surface of the convex part and does not cover at least part of the flat part;
A solid oxide fuel cell. 2. The solid oxide fuel cell according to claim 1, wherein the coating layer has a thickness of 0.001 mm or more and less than (0.5 × L).
L: Distance between the plurality of convex portions 3. The solid oxide according to claim 1, wherein a curvature radius R <b> 2 of an edge portion of the coating layer corresponding to the tip side edge portion is larger than a curvature radius R <b> 1 of the tip side edge portion of the convex portion. Fuel cell. The solid oxide fuel cell according to any one of claims 1 to 3, wherein the coating layer is formed by printing. The coating layer contains any of Ag, AgPd alloy, spinel material, and perovskite material,
The solid oxide fuel cell according to any one of claims 1 to 4, wherein the solid oxide fuel cell is provided. A flat portion having a flat shape, and a plurality of convex portions protruding from one surface of the flat portion and electrically connected to one electrode layer of the air electrode layer or the fuel electrode layer, and a metal material A step of preparing an interconnector formed from
Forming a coating layer covering the upper surface and at least a part of the side surface of the convex part and not covering at least a part of the flat part by printing;
A method for producing a solid oxide fuel cell, comprising: The step of forming the coating layer by printing includes a step of applying the paste to the plurality of convex portions by extruding a paste of a material constituting the coating layer from a plurality of openings of the mask. The method for producing a solid oxide fuel cell according to claim 6. 8. The method for manufacturing a solid oxide fuel cell according to claim 7, wherein the plurality of openings are arranged corresponding to the plurality of protrusions and have a diameter larger than those of the protrusions. The step of forming the coating layer by printing has a step of applying the paste to the plurality of convex portions by pressing a plate-like member to which the paste of the material constituting the coating layer is applied. A method for producing a solid oxide fuel cell according to claim 6. The paste contains any of Ag, AgPd alloy, spinel material, and perovskite material,
The method for producing a solid oxide fuel cell according to any one of claims 7 to 9. Providing a fuel cell body having an air electrode layer, a solid electrolyte layer, and a fuel electrode layer and having a power generation function;
Pushing the plurality of protrusions of the interconnector in which the coating layer is formed into one of the air electrode layer or the fuel electrode layer;
The method for producing a solid oxide fuel cell according to claim 6, further comprising:

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