JP5315656B2 - Stack structure of solid oxide fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inter-connector for a solid oxide fuel cell capable of preventing fuel cells from shifting and stably stacking, and a stack structure using the same inter-connector for the solid oxide fuel cell. <P>SOLUTION: In the inter-connector for a plate-shaped solid oxide fuel cell wherein a fuel electrode and an air electrode are arranged to sandwich an electrolyte, the inter-connector comprises a support member forming a through-hole where a fuel cell is fitted in, and a gas supply member arranged to block the through-hole of the support member and forming a recessed gas passage on the surface opposite to the through-hole. A shoulder section supporting the fuel cell is formed on a side wall surface of the through-hole of the support member. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an interconnector used in a solid oxide fuel cell operated by a fuel gas and an oxidant gas, and a stack structure in which a plurality of solid oxide fuel cells are stacked using the interconnector.

A fuel cell is a cell that can directly convert chemical energy generated when fuel is oxidized into electric energy while continuously supplying fuel from the outside and exhausting combustion products. The types of fuel cells are classified according to the electrolyte, and those using metal oxides having ion conductivity for the electrolyte are called solid oxide fuel cells. In many cases, a plurality of such solid oxide fuel cells are prepared and stacked. For example, Patent Document 1 discloses a single cell in which a fuel electrode, a solid electrolyte, and an air electrode are sequentially stacked on a concave conductive support plate to form a concave shape as a whole. The conductive support has a gas flow path formed therein, and can supply gas to the fuel electrode. When the single cells are stacked, the space formed by the recesses serves as a gas flow path for the air electrode, resulting in a two-chamber stack structure as a whole. Patent Document 2 discloses a single-chamber stack structure in which a plurality of solid oxide fuel cells are arranged at predetermined intervals with spacers interposed therebetween. In this stack structure, a gap is provided between adjacent batteries by the spacer, and this gap becomes a space through which gas flows.
JP 2007-173115 A JP 2005-174661 A

  However, in the stack structure as described above, a gap is formed between adjacent batteries, so that there is a problem that the overall stack structure has low rigidity. For example, there is a possibility that the battery may be displaced due to vibration or the like, and there is a problem that it is difficult to maintain a stable output.

  The present invention has been made in order to solve the above-described problem, and prevents the displacement of the battery, and can be stably stacked, and a stack using the same. The purpose is to provide a structure.

The present invention is an interconnector for a plate-shaped solid oxide fuel cell in which a fuel electrode and an air electrode are arranged so as to sandwich an electrolyte, and has been made in order to solve the above problems. A support member having a through-hole into which a battery is fitted, a gas supply member that is disposed so as to close the through-hole of the support member, and has a concave gas flow path formed on a surface facing the through-hole; A shoulder for supporting the fuel cell is formed on the side wall surface of the through hole of the support member, and a gas flow path leading from the side wall of the through hole to the side end surface is formed on the support member. .

  According to this configuration, the through hole into which the fuel cell is fitted is formed, and the shoulder portion for supporting the fuel cell is formed on the side wall surface of the through hole. Thereby, since a fuel cell is hold | maintained in a through-hole, the shift | offset | difference by a vibration, a crack, etc. can be prevented. In addition, since the fuel cell is disposed on the shoulder, by applying an adhesive such as a glass seal to the shoulder, gas leak can be prevented and the fuel cell can be more firmly fixed.

The stack structure of the solid oxide fuel cell according to the present invention is made in order to solve the above problem, and the fuel electrode and the air electrode are arranged so as to sandwich the plurality of interconnectors or the electrolyte. A plurality of interconnectors for a plate-shaped solid oxide fuel cell, the support member having a through-hole into which the fuel cell is fitted, and the through-hole of the support member. A gas supply member having a concave gas flow path formed on a surface facing the through hole, and a shoulder for supporting the fuel cell is formed on a side wall surface of the through hole of the support member. and has a plurality of interconnector, the fitted into the through holes of the interconnector, the fuel electrode so as to sandwich the electrolyte (the anode) and an air electrode (cathode) is arranged a plate-shaped solid oxide A fuel cell and a conductive member disposed between adjacent interconnectors, wherein the adjacent interconnectors are disposed such that the support member and the gas supply member of each interconnector face each other. The conductive member connects a fuel cell facing the outside through the through hole and a gas supply member facing the fuel cell.

  In the interconnector in the stack structure, there are various methods for connection between the fuel cell and the gas supply member. For example, between the surface facing the gas supply member side of the fuel cell and the gas supply member, It can connect by arrange | positioning the electroconductive member which can distribute | circulate gas. As such a conductive member, for example, a porous conductive material or a conductive mesh material can be used.

  Alternatively, a protrusion can be formed on the surface of the fuel cell electrolyte facing the gas supply member, and a fuel electrode or an air electrode can be formed at the tip of the protrusion. The electrode may be in direct contact with the gas supply member, or a sheet-like current collector may be interposed.

  The support member and the gas supply member can have various shapes, such as a plate shape, a sheet shape, and a block shape, and the planar shape can be various shapes such as a polygonal shape and a circular shape in addition to a rectangular shape. be able to.

  According to the present invention, it is possible to prevent battery misalignment and stably stack.

  Hereinafter, an embodiment of a stack structure of a solid oxide fuel cell according to the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view of an interconnector used in a stack structure of a solid oxide fuel cell according to this embodiment, and FIG. 2 is a plan view of FIG. First, the interconnector will be described.

  As shown in FIGS. 1 and 2, this interconnector X is composed of a rectangular support member 1 that supports the fuel cell and a rectangular gas supply member 2 joined to the lower surface thereof, both of which are conductive. It is made of sex material. The support member 1 and the gas supply member 2 can be joined by, for example, thermocompression bonding after metal plating. The fuel cell 3 used here is configured by forming a thin-film fuel electrode 33 on the upper surface of a rectangular plate-shaped electrolyte 31 and forming a thin-film air electrode 32 on the lower surface. A through hole 11 having the same shape as the fuel cell 3 is formed in the support member 1, and the fuel cell 3 is fitted into the through hole 11. At the lower part of the inner wall surface of the through hole 11, a shoulder shoulder 12 that supports the fuel cell 3 protrudes from the four sides in the center direction of the through hole 11. The air electrode 32 of the fuel cell 3 is formed to a size that does not contact the shoulder 12, that is, a size that faces the gas supply member 2 from the through hole 11 narrowed by the shoulder 12. Therefore, the electrolyte 31 of the fuel cell 3 is in contact with the shoulder 12, and here, the electrolyte 31 is fixed to the shoulder 12 by a glass seal (not shown). By sealing with such a glass seal, the gas flow between the fuel electrode 33 and the air electrode 32 is blocked in the through hole 11. Further, the depth of the through hole 11 is larger than the total thickness of the electrolyte 31 and the fuel electrode 33, so that the fuel electrode 33 does not protrude from the through hole 11.

  On the other hand, in the gas supply member 2, gas flow paths 21 including a plurality of grooves are formed in parallel on the upper surface, and open at both end portions of the gas supply member 2. The gas passage 21 is disposed so as to face the through hole 11 of the support member 1, and the gas passing through the gas passage 21 is supplied to the fuel cell 3. A porous sheet-like current collector (conductive member) 4 is arranged in the space between the air electrode 32 and the gas flow path 21, and thereby the fuel cell 3 and the gas supply The member 2 is electrically connected.

Next, the stack structure will be described. FIG. 3 is a side sectional view of the stack structure. As shown in the figure, this stack structure is such that three solid oxide fuel cells 3 are stacked by three interconnectors X. Each fuel cell 3 is fixed to the interconnector X described above. In this stack structure, the support member 1 and the gas supply member 2 of the adjacent interconnector X are arranged so as to face each other. An insulating spacer 5 is provided between the opposing support member 1 and the gas supply member 2, and a gap S is formed. A porous sheet-shaped current collector (conductive member) 6 is provided between the fuel electrode 33 of the fuel cell 3 and the lower surface of the gas supply member 2 so as to fill the gap S. ing. Thereby, three fuel cells are connected in series.

  Subsequently, materials constituting the fuel cell will be described. As the material of the electrolyte 31, those known as electrolytes for solid oxide fuel cells can be used. For example, ceria oxide (GDC) doped with samarium or gadolinium, lanthanum doped with strontium or magnesium An oxygen ion conductive ceramic material such as a galide oxide, zirconia oxide (YSZ) containing scandium or yttrium can be used.

  The fuel electrode 33 and the air electrode 32 can be formed of a ceramic powder material. The average particle size of the powder used at this time is preferably 10 nm to 100 μm, more preferably 50 nm to 50 μm, and particularly preferably 100 nm to 10 μm. In addition, an average particle diameter can be measured according to JISZ8901, for example.

As the fuel electrode 33, for example, a mixture of a metal catalyst and a ceramic powder material made of an oxide ion conductor can be used. As the metal catalyst used at this time, a material that is stable in a reducing atmosphere, such as nickel, iron, cobalt, or a noble metal (platinum, ruthenium, palladium, etc.) and has hydrogen oxidation activity can be used. In addition, as the oxide ion conductor, one having a fluorite structure or a perovskite structure can be preferably used. Examples of those having a fluorite structure include ceria-based oxides doped with samarium, gadolinium, and the like, and zirconia-based oxides containing scandium and yttrium. In addition, examples of those having a perovskite structure include lanthanum galide oxides doped with strontium and magnesium. Of the above materials, the fuel electrode 33 is preferably formed of a mixture of an oxide ion conductor and nickel. The mixed form of the ceramic material made of the oxide ion conductor and nickel may be a physical mixed form, or may be a powder modification to nickel or a nickel modification to ceramic material. Good. Moreover, the ceramic material mentioned above can be used individually by 1 type or in mixture of 2 or more types. The fuel electrode 33 can also be configured using a metal catalyst alone.

As the ceramic powder material forming the air electrode 32, for example, a metal oxide made of Co, Fe, Ni, Cr, Mn or the like having a perovskite structure or the like can be used. Specifically, (Sm, Sr) CoO ₃ , (La, Sr) MnO ₃ , (La, Sr) CoO ₃ , (La, Sr) (Fe, Co) O ₃ , (La, Sr) (Fe, Co , Ni) O _{3 and the} like, and (La, Sr) (Fe, Co) O ₃ is preferable. The ceramic material mentioned above can be used individually by 1 type or in mixture of 2 or more types.

  The fuel electrode 33 and the air electrode 32 can be formed by various methods. For example, it can be formed by a wet coating method or a dry coating method. Examples of the wet coating method include a screen printing method, an electrophoresis (EPD) method, a doctor blade method, a spray coating method, an ink jet method, a spin coating method, and a dip coating method. At this time, the fuel electrode 33 and the air electrode 32 need to be paste-like, and are formed by adding appropriate amounts of a binder resin, an organic solvent, and the like with the above-described material as a main component. More specifically, it is preferable to add a binder resin or the like so that the main component is 50 to 95% by weight in the mixing of the main component and the binder resin. Examples of dry coating methods include vapor deposition, sputtering, ion plating, chemical vapor deposition (CVD), electrochemical vapor deposition, ion beam, laser ablation, and atmospheric pressure plasma deposition. Alternatively, it can be formed by a low pressure plasma film forming method or the like. In addition, the electrolyte can be formed by the same method as the above-described fuel electrode and air electrode. However, if formed by a dry coating method or a sol-gel method, the electrolyte is generally at a lower temperature than the wet coating method. A dense metal oxide film can be formed.

The interconnector X and the current collectors 4 and 6 are made of a conductive metal or metal oxide material, and are made of Pt, Au, Ag, Ni, SUS materials, or La (Cr, Mg) O ₃ , (La, It can be formed of lanthanum chromite materials such as Ca) CrO ₃ and (La, Sr) CrO _3, and one of these may be used alone or a mixture of two or more. May be.

  In the stack structure configured as described above, power generation is performed as follows. First, an oxidant gas such as air is supplied to the gap S between the interconnectors X, and a fuel gas made of hydrocarbons such as hydrogen or methane or ethane is supplied from the gas flow path 21 of the gas supply member 2 into the stack structure. Supply. As a result, the fuel gas and the oxidant gas enter the stack structure and come into contact with the fuel electrode 33 and the air electrode 32 of each fuel cell 3 individually. Thus, since the fuel electrode 33 and the air electrode 32 are in contact with the fuel gas and the oxidant gas, respectively, oxygen ion conduction through the electrolyte 31 occurs between the fuel electrode 33 and the air electrode 32, and power generation is performed.

  As described above, according to the present embodiment, the through-hole 11 into which the fuel cell 3 is fitted is formed in the interconnector X, and the shoulder 12 for supporting the fuel cell is formed on the side wall surface of the through-hole 11. ing. Thereby, since the fuel cell 3 is held in the through-hole 11, it is possible to prevent displacement and cracking due to vibration. Further, since the fuel cell 3 is disposed on the shoulder portion 12, the fuel cell 3 can be more firmly fixed by applying a glass seal to the shoulder portion 12. Moreover, since the support member 1 and the gas supply member 2 are joined by metal plating and thermocompression bonding as described above, it is not necessary to use a sealing material, and gas leakage can be prevented.

  The embodiment of the present invention has been described above, but the present invention is not limited to this, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, the two-chamber type fuel cell is used. However, if a mixed gas is supplied, the single-chamber type can be used. In this case, the gas can be supplied from the side surface of the support member 1 by forming a gas flow path from the side wall of the through-hole 11 and opening the side end surface of the support member 1. Further, in the above embodiment, the fuel cell in which the thin-film fuel electrode and the air electrode are respectively formed on the upper surface and the lower surface of the plate-shaped electrolyte is used. It is also possible to use a so-called electrode-supported battery in which the other electrode and the electrolyte are formed in a thin film.

In the above embodiment, the porous current collector is filled in the gap between the fuel electrode of the fuel cell and the gas supply member, but a mesh-shaped current collector can also be used. Alternatively, the shape of the electrolyte can be changed. For example, as shown in FIG. 4, a part of the electrolyte 31 can be protruded from the through hole narrowed by the shoulder 12 toward the gas supply member 2 and brought into contact with the gas supply member 2. At this time, a sheet-like current collector may be disposed between the gas supply member 2 and the gas supply member 2. Further, the through hole does not have to be the same size as the fuel cell, and may have a shape that makes contact with at least a part of the side surface of the fuel cell. For example, it may be a through hole that comes into contact with the opposite side surfaces of the fuel cell. Even in this case, the fuel cell can be prevented from being displaced. In the above embodiment, the depth of the through hole is designed so that the fuel electrode 33 does not protrude from the through hole 11. However, the height of the opening of the through hole 11 and the upper surface of the fuel electrode 33 are the same. Alternatively, the depth of the through hole 11 can be adjusted so that the fuel electrode 33 protrudes. By doing so, the current collector 6 disposed between the interconnectors can be reliably connected.

1 is a side sectional view showing an embodiment of an interconnector used in a tack structure for extending a solid oxide fuel cell according to the present invention. It is a top view of the interconnector of FIG. It is a sectional side view of the stack structure using the interconnector of FIG. FIG. 7 is a side sectional view showing another example of the interconnector of FIG. 1.

Explanation of symbols

X interconnector 1 support member 11 through hole 12 shoulder 2 gas supply member 21 gas flow path 3 fuel cell 31 electrolyte 32 air electrode 33 fuel electrode

Claims (4)

A plurality of interconnectors for a plate-shaped solid oxide fuel cell in which a fuel electrode and an air electrode are arranged so as to sandwich an electrolyte, wherein the support member has a through-hole into which the fuel cell is fitted; and A gas supply member, which is disposed so as to close the through hole of the support member, and has a concave gas flow path formed on a surface facing the through hole, and on the side wall surface of the through hole of the support member, A plurality of interconnectors formed with shoulders for supporting the fuel cell;
A plate-shaped solid oxide fuel cell in which a fuel electrode and an air electrode are disposed so as to be fitted in the through holes of each of the interconnectors and sandwich the electrolyte;
A conductive member disposed between the adjacent interconnectors,
The adjacent interconnectors are arranged such that the support member and the gas supply member of each interconnector face each other,
The conductive member is a stack structure of a solid oxide fuel cell, which connects a fuel cell facing the outside from the through hole and the gas supply member facing the fuel cell. The stack structure of a solid oxide fuel cell according to claim 1, wherein a gas flow path leading from the side wall of the through hole to the side end surface is formed in the support member. A surface facing the gas supply member side in the fuel cell, between the gas supply member, capable conductive member circulation of gas is arranged, the solid oxide according to claim 1 or 2 Fuel cell stack structure. The surface facing the gas supply member side in the electrolyte of the fuel cell has protrusions formed at the tip of the protruding portion, the fuel electrode or the air electrode is formed, according to claim 1 or 2 Solid oxide fuel cell stack structure.

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