JPH0837011A - Fuel cell base board in hollow flat plate form - Google Patents

Abstract

PURPOSE:To provide a fuel cell base board in the form of hollow flat plate equipped with a heightned mechanical strength while characteristics including a high gastightness are maintained by covering a gas passage formed from a porous support with an electrode material. CONSTITUTION:A plurality of oxidator gas passages 11 are provided in a porous support 9, which, is covered with an electrode material 10. A fuel cell base board in the form of hollow flat plate produced in this manner is equipped with an enhanced mechanical strength and also can be given such characteristics required of an electrode material as electric conductivity, reactivity, etc. Thus a fuel cell base board with a high mechanical strength can be fabricated while a high gas-tightness, etc., is maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow flat plate type fuel cell substrate for use in a solid oxide fuel cell, which is composed of an electrode material and a porous support and has a gas passage therein.

[0002]

2. Description of the Related Art A fuel cell is a general term for generating electric power by supplying two kinds of gases, an oxidant and a fuel, to an oxidant electrode and a fuel electrode. The solid oxide fuel cell described here is composed of constituent materials. A solid substance is used for all, and specifically, the following ceramics are listed as main materials.

Electrolyte; Yttria-stabilized zirconia (hereinafter, YSZ) fuel electrode; Nickel zirconia cermet (hereinafter, Ni-
YSZ) Oxidizer electrode; lanthanum manganite (hereinafter, LSM) The basic structure of one power generation cell of this fuel cell is that two electrodes are arranged on both sides of the electrolyte, but the output voltage of this cell is also open circuit voltage. It is less than 1V. Therefore, in order to obtain a practical output, it is necessary to have a structure in which such cells are laminated in multiple layers. FIG. 7 shows an example of the structure of a solid oxide fuel cell composed of a plurality of stacked cells. In the figure, 1 is a solid electrolyte, 2 is a fuel electrode, 3 is an oxidizer electrode, 4 is an interconnector, 5 is a fuel gas channel, 6 is an oxidant gas channel, and 7 is a unit cell. By supplying the fuel gas and the oxidant gas to the solid oxide fuel cell having such a structure, a predetermined electric output can be obtained. In the power generation in the solid oxide fuel cell having this structure, it is necessary to stack the gases so that the supplied gases can effectively spread to the respective reaction surfaces and that leakage from the ends of the electrodes does not occur in the periphery. . However, in the solid oxide fuel cell having the structure shown in FIG. 7, it is extremely difficult to secure the airtightness between each unit cell 7 and the interconnector 4 in the actual stacking. This is because it is extremely difficult to obtain gas tightness at the joint surface because all the above-mentioned constituent members are made of ceramics that are not flexible or deformable during compression. It is difficult to solve such a problem even if the flatness of the member is extremely improved. In addition, when the power generation cell of the solid oxide fuel cell is actually manufactured by the sintering method, there is a warp or the like. Considering that the occurrence of is unavoidable, it is almost impossible to realize. In the case of the method shown in FIG.
When the thickness of the electrolyte, which is the component having the smallest electrical conductivity, increases, the internal resistance of the battery increases and the power generation characteristics of the cell deteriorate, so it is necessary to reduce the thickness of the electrolyte. However, when the thickness of the electrolyte is reduced, the strength of the unit cell 7 decreases. Therefore, if a large pressure is applied from above and below the battery in order to improve the airtightness between the unit cell 7 and the interconnector 4, the unit cell 7 May be destroyed.

[0004] Therefore, as one method of solving the problem that it is difficult to ensure the gas tightness when such a laminated, the gas flow path inside the one electrode material in which either 8 A method has been proposed in which a hollow substrate (hollow flat plate-shaped oxidizer electrode) 3'having the above is prepared and a power generation section is formed on the hollow substrate 3 '(Japanese Patent Laid-Open No. 05-36417). In the figures, those parts corresponding to the same parts in the other figures are designated by the same reference numerals, and a description thereof will be omitted. In such a system, the substrate 3 '
Since the wall surface of the gas flow path of 1 acts as an electrode, the gas that reacts using this substrate 3'as an electrode is not the flow path formed by combining the unit cell 7 and the interconnector 4, but the flow provided in the substrate 3 '. Flow through the road. Therefore, the gas-tightness can be secured simply by applying gas seals to both ends of the substrate,
The sealability can be greatly improved. Further, since it is not necessary to apply a large pressure from above and below the battery in order to enhance the gas tightness, it is possible to obtain excellent characteristics in terms of life.

[0005]

However, the functions required for the electrodes of the solid oxide fuel cell are that they have high electrical conductivity and that the area of the interface between the electrolyte and the electrodes where the electrode reaction takes place is large. It has many functions such as high gas permeability and high mechanical or thermal strength. In particular, the area of the interface between the electrolyte and the electrode is wide,
In addition, in order to produce an electrode having high gas permeability, it is necessary to increase the porosity of the electrode.
This weakens the mechanical strength of the substrate, which causes the reliability and durability of the fuel cell to deteriorate. Therefore, it was very difficult to manufacture a substrate satisfying all of these required conditions with a single electrode material.

The present invention has been made in view of the above circumstances. An electrode material having a large interface area between the electrolyte and the electrode, high gas permeability, and high mechanical strength is used as at least one of the constituent materials. It is an object of the present invention to provide a hollow flat plate fuel cell substrate used for a part.

[0007]

In order to achieve the above object, a hollow flat plate fuel cell substrate of the present invention is used in a solid oxide fuel cell, and is a hollow flat plate having a plurality of flow passages arranged therein. The substrate of (1) has a structure in which a porous support that forms a flow channel is provided inside the substrate, and the porous support is coated with an electrode material.

Further, the hollow flat plate type fuel cell substrate of the present invention comprises:
As the porous support, a flat plate-like support having a plurality of flow paths inside is used, and at least one through hole penetrating from the upper surface to the lower surface of the support and not intersecting the flow paths is used. It has a structure in which the through hole is filled with an electrode material.

The hollow flat plate type fuel cell substrate of the present invention comprises:
As the porous support, a plurality of supports each having a tubular shape and having openings at both ends thereof are used, and both ends of the support are exposed at the end surface of the fuel cell substrate.

The hollow flat plate type fuel cell substrate of the present invention comprises:
The shape of the porous support is a comb shape in which tubular members are combined, and an opening is provided at least at two or more locations on the end of the comb support, and the opening is at one location on the substrate. It is characterized in that it has a shape exposed at the end face of the.

The hollow flat plate type fuel cell substrate of the present invention comprises:
It is characterized in that the electrode material has a structure in which the upper surface and the lower surface of the substrate are continuous between a plurality of supports arranged in the substrate.

[0012]

With the above means, the hollow flat plate type fuel cell substrate of the present invention has the following actions. In the invention according to claim 1, the porous support made of a material having a higher mechanical strength than the electrode material is disposed inside the fuel cell substrate to enhance the mechanical strength of the substrate, while it is required as an electrode. With respect to electric conductivity and reactivity, it is possible to impart the required characteristics to the substrate by coating the surface with an electrode material. Therefore, it becomes possible to manufacture a substrate having improved mechanical strength while maintaining characteristics such as high gas-tightness as compared with the conventional hollow flat battery substrate composed of only electrode materials.

According to the second aspect of the present invention, by using the flat plate-shaped porous support, the strength of the entire surface of the substrate is increased, and at least one or more through holes are provided in the support, and the through holes are provided. By filling the inside with the electrode material, the electrical connection between the upper surface and the lower surface of the substrate is made not only through the side surface of the substrate but also through the through holes, so that the substrate having the porous support has a small electric resistance. Can be manufactured.

According to the third aspect of the invention, the support is made easy by forming the porous support into a simple cylindrical shape. Further, in the invention according to claim 4, since the gas flow path is folded back in the substrate, the gas inlet and the outlet in the substrate can be provided at one end face of the substrate. As a result, when stacking cells with electrodes and interconnectors formed on this substrate, there is only one connection between the gas flow path of the battery container and the cells, and gas that is difficult to work in stacking. It is possible to have only one seal portion, and it is possible to improve the reliability and durability of the fuel cell.

Further, in the invention according to claim 5, the electrode material has a structure in which the upper surface and the lower surface of the substrate are continuous in a portion between the supports arranged in the substrate.
It is possible to reduce the resistance to the current flowing between the upper surface and the lower surface of the substrate during the operation of the cell, and it is possible to configure a fuel cell having a higher output.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings with reference to the drawings. The present invention is not limited to the following examples. [Embodiment 1] FIG. 1 is a perspective view showing the appearance of a hollow flat plate type fuel cell substrate according to an embodiment of the present invention, and FIG.
3 is a perspective view of a cross section taken along the line XX ′ in FIG. In the figure, 9 is a porous support, 10 is an electrode material, 11 is a gas flow path, and 12 is a through hole. Calcia-stabilized zirconia (hereinafter CSZ) containing 15 mol% of calcia was used as a raw material for the support 9.
As the electrode material 10, a powder of La0.8Sr0.2MnO3 having a perovskite structure and having a particle diameter of 1 to 3 μm, which is generally widely used as an oxidizer electrode material of a solid oxide fuel cell, was used.

The support 9 was produced by sintering an extruded body. The clay-like material used for extrusion molding is a mixture of 100 parts of CSZ raw material powder, about 5 parts of methylcellulose water-soluble polymer as a binder, and 10 parts of water (mixing ratio on a weight basis), and then kneaded by a raw material kneader. It was produced by Using the vacuum extrusion molding machine, the material produced in this way was made into a flat plate extrusion molding having a flow passage penetrating the inside thereof. After drying, the through holes 12 were cut out, and then degreased by heating at 400 ° C. for 4 hours, and thereafter, heating was performed at 1600 ° C. for 4 hours to sinter. The size of the hollow flat plate-shaped support after sintering is, for example, 100 mm in width, 150 mm in length and 5 mm in thickness.

Hollow flat plate-shaped support 9 produced by the above steps
Was coated with electrode material 10. Coating is slurry coating,
It was done by sintering. La0.8Sr0.2MnO3 powder, which is an electrode material, was used as a raw material powder for preparing a slurry, and polyethylene glycol and ethanol were added at 20% by weight ratio to obtain a slurry. The slurry is applied onto the support 9 and dried, and then the electrode material 1 is contracted by contraction.
The flatness of the substrate surface was improved by applying the slurry to the portion of the through hole 12 of the support body 9 in which 0 was depressed and drying it. Next, the coating part was formed by degreasing by heating at 400 ° C. for 4 hours and then baking at 1300 ° C. for 2 hours.

The bending strength of the thus manufactured hollow flat plate fuel cell substrate was measured and found to be about 17 MPa. Since the bending strength of the substrate formed of the conventional electrode material was about 6 MPa, by disposing the flat plate-shaped porous support member 9 inside the substrate, the bending strength of the substrate increased nearly three times. .

[Embodiment 2] FIG. 3 is a perspective view showing an outer appearance of a hollow flat plate type fuel cell substrate according to another embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along the line XX 'of FIG. It is a perspective view. In the figures, those parts corresponding to the same parts in the other figures are designated by the same reference numerals, and a description thereof will be omitted. The cylindrical support 9 used in this example was produced by using the same raw material as in Example 1 and sintering an extruded body in the same manner as in Example 1. The size of one support 9 after sintering is, for example, an outer diameter of 4 mm and a length of 150 mm.

The coating with the electrode material 10 was performed by a pressing method. First, with respect to the raw material powder 100 for the oxidizer electrode, about 5 parts of the methylcellulose-based water-soluble polymer, which is the binder,
After adding water 10 (mixing ratio on a weight basis), the raw material kneader was kneaded to prepare a clay-like electrode material 10.
The electrode material 10 produced in this manner is laid flat in a rectangular frame made of stainless steel to a thickness of about 4 mm, and the fired supports 9 are arranged at a predetermined interval thereon, and a clay-like material is formed thereon. The electrode material 10 was placed again with a thickness of about 4 mm, a stainless steel cylinder fitted to the inner dimensions of a rectangular frame was placed thereon, and the substrate was formed by compressing from above and below with a press machine at a pressure of 10 kg. Then, a substrate was prepared by performing degreasing and sintering under the same conditions as in Example 1.

The bending strength of the thus manufactured hollow flat fuel cell substrate was about 11 MPa. [Embodiment 3] FIG. 5 is a perspective view showing an outer appearance of a hollow flat plate type fuel cell substrate according to still another embodiment of the present invention, and FIG. 6 is a perspective view of a cross section taken along the plane XX 'of FIG. Is. In the figures, those parts corresponding to the same parts in the other figures are designated by the same reference numerals, and a description thereof will be omitted. The comb-shaped support 9 was produced by the procedure shown below. First, using the same raw material as in Example 1, a cylindrical member is formed by extrusion molding. After drying, one end of a single cylindrical member cut into a predetermined length is sealed with the clay-like material used for extrusion molding.
Further, a cutout is provided in a portion of the member whose both ends are sealed to which the cylindrical member corresponding to the teeth of the comb is bonded so that the hollow portion in the cylinder appears. Next, water is applied to the cut portion of the cylindrical member and one end of the cylindrical member cut into a predetermined length to slightly dissolve the binder in each member,
Glue these parts together. Further, the bonded portion was reinforced with a clay-like member. After making a comb shape like this,
It is dried again, and then degreased under the same conditions as in Example 1,
Sintering was performed.

The coating with the electrode material 10 was carried out by the pressing method as in Example 2. The bending strength of the hollow flat-plate fuel cell substrate produced in this way was measured to be about 1
It was 1 MPa.

In the above-mentioned embodiment, the oxygen electrode material is used as the coating material for the support 9, but a fuel electrode material may be used. Further, as the material of the porous support 9, in addition to CSZ, YSZ, alumina, magnesia,
Examples include ceria. Furthermore, as the cross-sectional shape of the gas flow path in the substrate, a square is used in the first embodiment, and a square shape is used in the second and third embodiments.
In the above, the circular shape is used, but other polygonal shapes such as a triangle and a hexagon, and an elliptical sectional shape may be used. Further, the shape of the substrate may be a shape other than the rectangular parallelepiped used in the above-mentioned embodiment, depending on the shape of the cell container or the like.

[0025]

As described above, the present invention has the following effects. That is, according to the hollow flat plate type fuel cell substrate according to claim 1, the gas flow path formed by the porous support is covered with the electrode material, which is an advantage of the conventional hollow flat plate type fuel cell substrate. It has become possible to increase the strength of the substrate without damaging features such as ease of sealing. As a result, the reliability and durability of the hollow flat plate solid oxide fuel cell are improved, and the output of the fuel cell can be easily increased by increasing the size of the fuel cell, and an extremely large effect can be obtained industrially. Can be done.

Further, according to the hollow flat plate fuel cell substrate of the second aspect, the same effect as that of the hollow flat plate fuel cell substrate of the first aspect is obtained, and a flat plate-shaped porous support is adopted. By increasing the strength of the entire surface of the substrate by forming a through hole in the support and filling the inside with an electrode material, the current flowing between the upper surface and the lower surface of the substrate can be transmitted not only through the side surface of the substrate but also through the substrate. It was possible to flow into the holes, and it became possible to suppress an increase in internal resistance of the battery.

According to the hollow flat plate fuel cell substrate of the third aspect, the same effect as that of the hollow flat plate fuel cell substrate of the first aspect is obtained, and the porous support has a simple tubular shape. By making it possible to facilitate the production of the support and the substrate having the support.

Further, according to the hollow flat plate type fuel cell substrate of the fourth aspect, the same effect as that of the hollow flat plate type fuel cell substrate of the first aspect can be obtained, and the gas flow path is folded back in the substrate to form the substrate. When the fuel cell is assembled with the unit power generation cell manufactured using the substrate of the present invention by providing the gas flow path opening only on the end face of the single cylinder, the gas flow path of the fuel cell container and the unit power generation cell It has become possible to connect the gas flow passage to one cylinder. As a result, the portion where the gas seal is required is only this one cylinder per unit power generation cell, which facilitates the assembly of the fuel cell stack and further enhances the reliability and durability of the cell.

Further, according to the hollow flat plate type fuel cell substrate of the present invention, the electrode material is continuous from the upper surface to the lower surface of the substrate in the portion between the supports arranged in the substrate. As a result, it is possible to reduce the resistance to the current flowing between the upper surface and the lower surface of the substrate during the operation of the cell, and it is possible to construct a fuel cell having a higher output.

[Brief description of drawings]

FIG. 1 is a perspective view showing the appearance of an embodiment of a hollow flat plate fuel cell substrate according to the present invention.

FIG. 2 is a perspective view of a cross section taken along the plane XX ′ of the hollow flat plate fuel cell substrate of the embodiment shown in FIG.

FIG. 3 is a perspective view showing an appearance of another embodiment of the hollow flat plate type fuel cell substrate according to the present invention.

FIG. 4 is a perspective view of a cross section taken along the plane XX ′ of the hollow flat plate fuel cell substrate of the embodiment shown in FIG.

FIG. 5 is a perspective view showing the appearance of yet another embodiment of the hollow flat plate type fuel cell substrate according to the present invention.

6 is a perspective view of a cross section taken along the line XX ′ of the hollow flat plate fuel cell substrate of the embodiment shown in FIG.

FIG. 7 is an exploded perspective view of an assembled state of a conventional solid oxide fuel cell.

FIG. 8 is a perspective view of a conventional solid oxide fuel cell using a substrate having a gas channel inside.

[Explanation of symbols]

1 ... Electrolyte, 2 ... Fuel electrode, 3 ... Oxidizer electrode, 3 '... Substrate (hollow flat plate oxidizer electrode), 4 ... Interconnector, 5 ... Fuel gas flow path, 6 ... Oxidant gas flow path, 7 ... Single cell, 8 ... Dense film, 9 ... Porous support, 10 ... Electrode material, 11 ... Gas flow path, 12 ... Through hole.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsumi Manabe 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Himeko Kanagawa 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (5)

[Claims] 1. A hollow flat plate-shaped substrate for use in a solid oxide fuel cell in which a plurality of channels are arranged, the substrate having a porous support for forming channels, A hollow flat plate fuel cell substrate having a structure in which the porous support is covered with an electrode material. 2. A flat plate-shaped support having a plurality of flow channels therein is used as the porous support, and the support has a through hole that penetrates from the upper surface to the lower surface and does not intersect the flow channels. 2. The hollow flat plate type fuel cell substrate according to claim 1, which has at least one of the above, and has a structure in which the through hole is filled with an electrode material. 3. A plurality of supports having a cylindrical shape and having openings at both ends thereof are used as the porous support, and both ends of the support are exposed at an end face of a fuel cell substrate. The hollow flat plate type fuel cell substrate according to claim 1. 4. The porous support has a comb shape in which tubular members are combined, and has openings at least at two or more end portions of the comb support, and the openings are provided. 2. The hollow flat plate type fuel cell substrate according to claim 1, wherein is a shape exposed at one end surface of the substrate. 5. The hollow flat plate type fuel cell substrate according to claim 3, wherein the electrode material has a structure in which a plurality of supports are arranged in the substrate and the electrode material is continuous from the upper surface to the lower surface of the substrate.