JP2002170577A - Separator for fuel battery and fuel battery using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator for a fuel battery, a fuel battery using it, and a method for manufacturing a fuel battery wherein a joint part is suppressed from cracking or the like under a thermal stress to prevent increase of an internal resistance while an output density is improved, resulting in a lower manufacturing cost. SOLUTION: The separator for a fuel battery is provided wherein a conductive substrate 1 is held between an upper part electrode layer 3a and a lower part electrode layer 4a, with a lower surface comprising a groove 20a. Here, the material of the upper part electrode layer is identical with an electrode material which is at the bottom part of a cell laminated on the upper surface while the material of the lower part electrode layer is identical with an electrode material which is at the top of a cell coated on the lower surface. The fuel battery comprises a fuel battery stack where the cell and the separator for the fuel battery are combined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell separator, a fuel cell using the same, and a fuel cell manufacturing method. More specifically, the present invention relates to a small and highly reliable flat type SO.
The present invention relates to a fuel cell separator that can be used for FC, a fuel cell using the same, and a fuel cell manufacturing method.

[0002]

2. Description of the Related Art A fuel cell is constructed such that a solid electrolyte having ion conductivity such as oxygen ions or protons is sandwiched between a porous air electrode and a fuel electrode, and an oxidizing gas containing oxygen gas is provided on the air electrode side. Is supplied to the fuel electrode side with a reducing gas containing hydrogen or carbonized gas, and these gases electrochemically react via a solid electrolyte to generate an electromotive force. However, the electromotive force obtained by a single fuel cell (cell) is as small as about 1.12 V, and a plurality of cells must be connected in series / parallel to be used as a home power supply or a vehicle power supply.

[0003] The cells of a solid oxide fuel cell (hereinafter abbreviated as "SOFC"), which is one type of fuel cell, can be roughly classified into a cylindrical type in which an electrode and a solid electrolyte are coated around a cylinder, a solid electrolyte, and the like. There are two types of flat type in which the electrodes are formed in a flat shape. Cylindrical SO combining cylindrical cells
In FC, it is difficult to increase the area of the power generation section of the cell (the area of the solid electrolyte), and the power generation density per unit volume when the cell is connected is low. It is a fundamental problem. On the other hand, a flat-plate SO that combines a flat-type cell plate (cell plate)
The FC is a structure advantageous for increasing the power density per unit volume of the battery, and is an SOFC suitable for a mobile power supply requiring a smaller volume. In addition, this flat type SOF
As a technique for further increasing the output density of C, there is a flat panel SOFC in which the thickness of a solid electrolyte layer is formed thin by a thin film process in order to reduce the series resistance component of the SOFC. A conventional method of manufacturing a flat-plate SOFC using a general thin film process has been to deposit a solid electrolyte thin film on a porous electrode substrate using a thin film process such as plasma spraying or printing. . However, in order to form a homogeneous solid electrolyte membrane having no pinholes on a porous substrate, it is necessary to make the thickness sufficiently large, and it has been difficult to greatly reduce the series resistance component of the SOFC.

Therefore, Japanese Patent Application Laid-Open No. 8-64216 proposes an SOFC in which a solid electrolyte film thickness is 2 μm by forming a non-porous Si wafer as a supporting substrate. The structure of this flat type SOFC is shown in FIGS.
Shown in This flat type SOFC is configured by stacking a cell plate 11 and a separator 12. The structure of the cell plate 11 has a large number of small holes uniformly distributed.
i-substrate 7, solid electrolyte thin film 8 deposited thereon (stabilized zirconia single crystal thin film), and air electrode film 9 deposited on the solid electrolyte thin film 9 (La0.8Sr0.2MnO3)
And the fuel electrode film 1 attached to the surface opposite to the air electrode film 9
0 (CeO2), which is composed of a fuel electrode (Ni oxide) deposited on the surface of the Si substrate opposite to the surface on which the air electrode film is deposited. The Si substrate 7 is a (100) -oriented single-crystal Si substrate having a resistivity of 0.001 to 0.002 Ωcm by phosphorous doping and having both surfaces mirror-polished (FIG. 12). Further, as shown in FIG. 4, the structure of the separator 12 is a structure in which a gas passage portion having a depth of 2 mm is formed on both surfaces of the Si substrate using a dicing saw. The Si substrate used for the separator 12 is made of the same material as the substrate used for the cell 11, and has a thickness of about 5 mm and is mirror-polished on both sides.
A substrate is used.

The cell plate 11 and the separator 12
In the lamination method of (1), the lower part of the cell plate 11 and the upper part of the separator 12 use Si bonding of mirror-surface Si (FIG. 6-15), and electrical conduction is possible between the lower part of the cell plate 11 and the upper surface of the separator 12. For lamination of the upper part of the cell plate 11 and the lower part of the separator 12, a phosphor silicate glass 13 is applied to the peripheral part of the upper part of the cell plate 11, and the lower part of the separator 12 is pressed at high temperature (FIG. 6-14). At this time, a conductive silver paste 16 is applied in advance to a portion below the separator 12 and in contact with the air electrode 9 on the uppermost surface of the cell plate 11 to ensure more reliable electrical conduction (FIG. 6).

[0006]

In the above-mentioned flat type SOFC using the cell plate 11 and the separator 12, a solid electrolyte thin film can be formed on a non-porous Si substrate. Can be greatly reduced. However, in the lamination of the cell plate 11 and the separator 12, the joining portion between the upper portion of the cell plate 11 and the lower portion of the separator 12 is joined by the phosphosilicate glass 13, and due to a difference in material characteristics from the surroundings, joining by thermal stress is performed. There was a concern about cracking of the part and gas leakage accompanying the cracking. In addition, since the conductive paste for ensuring conduction between the upper part of the cell plate 11 and the lower part of the separator 12 comes into contact with the oxidizing gas, deterioration of conductivity due to oxidation of the conductive paste,
That is, there was a concern that the resistance inside the battery would increase.

The present invention has been made in view of such problems of the prior art, and an object of the present invention is to prevent cracks and the like caused by thermal stress in a joint portion and prevent an increase in internal resistance. Another object of the present invention is to provide a fuel cell separator capable of improving output density and reducing manufacturing costs, a fuel cell using the same, and a fuel cell manufacturing method.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, the joint surface of the separator and the joint surface of the cell are made of the same material, and the gas passage (groove) is formed. The above problems can be solved by forming a structure surrounded by a fuel electrode material or an air electrode material, providing a gas flow path only on one side of the separator, and fabricating the separator and the cell in the same process. And completed the present invention.

That is, the fuel cell separator of the present invention comprises:
In a fuel cell separator inserted between cells, a cell is formed by sandwiching a conductive substrate between an upper electrode layer and a lower electrode layer, has a groove on the lower surface, and has the upper electrode layer material laminated on the upper surface. And the material of the lower electrode layer is the same as the uppermost electrode material of the cell covered on the lower surface.

[0010] The fuel cell of the present invention is characterized by including a fuel cell stack formed by combining the fuel cell separator and the cell.

In a preferred embodiment of the fuel cell according to the present invention, the cell has a laminated structure in which a solid electrolyte layer and a conductive substrate are sandwiched between an upper electrode layer and a lower electrode layer, and the solid electrolyte layer has a lower surface. A conductive substrate, the conductive substrate is provided with a groove having a through hole in a part thereof, the upper electrode layer is laminated on the upper surface of the solid electrolyte layer, and the lower electrode layer is disposed on the lower surface of the conductive substrate. Is coated on the lower surface of the solid electrolyte layer via the through hole.

Further, in another preferred embodiment of the fuel cell of the present invention, the material of the upper electrode layer of the cell is the same as the material of the lowermost electrode layer of the separator above the cell.
The material of the lower electrode layer of the cell is the same as the material of the uppermost electrode layer of the separator below the cell.

[0013] Further, a fuel cell manufacturing method according to the present invention is a method for manufacturing the fuel cell, wherein the separator and the cell are stacked on each other and fired at a time to form a fuel cell stack. I do.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a fuel cell separator of the present invention will be described in detail with reference to FIGS. In this specification, “%” indicates mass percentage unless otherwise specified.

As shown in FIG. 1, the fuel cell separator of the present invention is inserted between cells and functions as a connector for connecting adjacent cells in series. As shown in FIG. 2, the separator includes a conductive substrate 1 sandwiched between an upper electrode layer (air electrode layer 3a) and a lower electrode layer (fuel electrode layer 4a). Road 20a)
Having. In other words, the flat surface and the gas passage 20a
Is formed by coating the air electrode layer 3a on the surface of the conductive substrate 1 having the back surface on which is formed, and coating the fuel electrode layer 4a on the back surface. The groove (gas flow path 20a) shown in FIG. 2 has a structure that does not penetrate the conductive substrate 1, but a part of the groove penetrates the substrate 1, and the air electrode layer 3a and the fuel electrode layer 4a
May be in contact with the structure. In addition, the gas flow path 20
a can be typically formed by mechanical processing such as dicing saw, electric discharge processing, and chemical processing such as etching.

Further, the material of the upper electrode layer 3a is applied to the electrode material at the bottom of the cell laminated on the upper surface (FIG. 3B).
The material of the lower electrode layer 4a is the same as the electrode material (FIG. 3-4b) at the uppermost part of the cell covered on the lower surface. As a result, when the separator has a laminated structure with the cell, the gas flow path (20a and 20b) is configured to be surrounded by only the fuel electrode layer or the air electrode layer. Is suppressed. That is,
When used as a fuel cell, an increase in the internal resistance of the cell can be prevented.

The upper electrode layer may be a reduction electrode or an oxidation electrode, and the lower electrode layer may be an oxidation electrode or a reduction electrode, depending on the configuration of the adjacent cells. For example, the covering position (adhering surface) of the air electrode layer 3a and the fuel electrode layer 4a of the separator shown in FIG. 2 can be reversed.

Next, the fuel cell of the present invention will be described in detail with reference to FIGS. This fuel cell includes a fuel cell stack formed by combining the above-described separator and the cell shown in FIG. 3, and such a fuel cell stack is configured such that the separator and the cell are mutually connected as shown in FIG. It is composed of stacked layers. Note that, in the fuel cell stack shown in FIG.
It is a state where a plurality of these are rigidly connected two-dimensionally in a direction substantially perpendicular to the laminating direction.

Here, as shown in FIG.
It is preferable to have a laminated structure in which the solid electrolyte layer 2 and the conductive substrate 1 are sandwiched between an upper electrode layer (fuel electrode layer 4b) and a lower electrode layer (air electrode layer 3b). The conductive substrate 1 is provided with a groove having a through hole in a part thereof, and by having the through hole, a fuel gas or air passing through the groove forms a three-layer interface with an electrode and an electrolyte. Function.

The upper electrode layer 4b may be a reduction electrode or an oxidation electrode depending on the configuration of the adjacent separator.
The lower electrode layer 3b can be an oxidation electrode or a reduction electrode. For example, the surfaces of the air electrode 3b and the fuel electrode 4b of the cell shown in FIG. 3 can be reversed.

The material of the upper electrode layer 4b of the cell is the same as the material of the lowermost electrode layer (FIG. 2-4b) of the separator above the cell, and the lower electrode layer 3b of the cell is formed. Is preferably the same as the material of the uppermost electrode layer (FIG. 2-3B) of the separator below the cell. Thus, the joint surface between the cell and the separator can be made of the same material, and destruction of the joint surface between the cell and the separator due to a difference in thermal expansion coefficient or the like can be suppressed. Further, it is preferable to use silicon as a material of the conductive substrate included in the cell and the separator. In this case, the groove processing of the cell and the separator can be facilitated by using the anisotropic etching technique of Si, and various film forming techniques used in the fabrication technique of the semiconductor device can be easily changed to the solid electrolyte, It can be used for forming an electrode layer.

Next, a method for manufacturing the fuel cell of the present invention will be described. Such a fuel cell manufacturing method is characterized in that the separator and the cells are stacked on each other and fired at a time to form a fuel cell stack.

Here, an example of a method of manufacturing the separator will be described with reference to FIG. The separator manufactured in FIG. 7 can form a fuel cell in combination with a plurality of cells (cell plates). First, a substrate 1 having electronic conductivity
The upper surface of (for example, a single crystal silicon substrate) is coated with an air electrode film 3a (for example, a lanthanum manganese composite oxide mixed with Sr). The coating method at this time is typically a physical vapor deposition method such as sputtering or ion plating, a chemical vapor deposition method such as plasma CVD,
And a liquid phase growth method such as electroless plating.
Next, a part of the lower surface (the surface that is not adhered) of the conductive substrate 1 is removed to form the gas flow path 20a. The gas flow path 20a can be typically formed by mechanical processing such as a dicing saw, electric discharge processing, and chemical processing such as etching. Further, a fuel electrode layer 4a (for example, nickel oxide) is coated on the lower surface (the gas flow channel forming surface) of the conductive substrate 1, and a separator having a gas flow channel 20a on one surface is obtained. Note that the fuel electrode layer 4a can be typically covered by the same method as the above-described air electrode layer 3a.

Next, an example of a method for manufacturing the above cell will be described with reference to FIG. Here, a method for manufacturing a cell in which a plurality of cells are two-dimensionally connected and integrated in a direction substantially perpendicular to the laminating direction of a conductive substrate, a solid electrolyte layer, and the like will be described. It is not at all different from the manufacturing method.

First, a substrate 1 having electronic conductivity (for example,
A solid electrolyte 2 (for example, yttria-stabilized zirconia) and a fuel electrode 4b (for example, nickel oxide) are laminated in this order on the upper surface of a single-crystal silicon substrate). The electrode layer 4b is formed (FIG. 8). As the lamination method at this time, typically, a physical vapor deposition method such as sputtering or ion plating, a chemical vapor deposition method such as plasma CVD, and a liquid phase growth method such as electroless plating are employed. it can.
Next, a gas flow path 20b (groove) is formed on the lower surface of the conductive substrate 1 where the solid electrolyte layer 2 / fuel electrode layer 4b is not formed, and a through hole 30 is provided in a part of the gas flow path 20b.
A portion where the electrode layer 3b on the gas flow path side and the solid electrolyte layer 2 are in contact with each other is distributed in the substrate surface. For example, a through hole 30 as shown in FIG. 11 can be formed. At this time, as a method of forming a gas flow path and a through hole, typically, machining such as a dicing saw, electric discharge machining, and chemical machining by etching or the like can be adopted. The diameter (width) of the through hole 30
May be the same as the width of the gas flow path 20b, or may be larger or smaller than this. Furthermore, an air electrode layer 3b (for example, a gas flow path / through hole forming surface)
Sr mixed lanthanum manganese composite oxide)
A cell plate is obtained. As a method of coating the air electrode layer 3b, typically, a physical vapor deposition method such as sputtering or ion plating, a chemical vapor deposition method such as plasma CVD, or a liquid vapor deposition method such as electroless plating are used. A growth method can be adopted. The obtained cell plate has a gas flow path 20b having an opening at a predetermined position, and the air electrode layer 3b / solid electrolyte layer 2 / fuel electrode layer 4b
To form a laminated structure.

Next, a method of manufacturing a fuel cell stack will be described with reference to FIG. 9 showing a preferred embodiment. Such a fuel cell stack is obtained by stacking the above-described separators and cell plates (cells). FIG. 9 shows a state where the separator A1 / cell B / separator A2 are stacked in this order from the bottom. That is, the upper surface (flat surface) of the separator A1 is joined to the lower surface (gas flow channel forming surface) of the cell B, and the lower surface (gas flow channel forming surface) of the separator A2 is bonded to the upper surface (flat surface) of the cell.
To join. At this time, the joining surface (electrode layer) between the separator and the cell is made of the same material as described above. For example,
A slurry of the same material as the electrode layer on the lower surface of the cell B is applied to the upper surface of the separator A1, and a slurry of the same material as the electrode layer on the gas flow path side of the separator A2 is applied to the upper surface of the cell B;
These are laminated and fired at once to produce a fuel cell (SOFC)
A stack is obtained.

Further, the gas flow path 20a of the separator and the gas flow path 20b of the cell are arranged so as to be substantially perpendicular to each other and at right angles to each other from the laminating direction of the separator and the cell. It is preferable from the viewpoint of the overall structural strength when laminated. The electrode layers of the separator and the cell are not coated at the time of lamination, but are coated by physical vapor deposition such as sputtering or ion plating, chemical vapor deposition such as plasma CVD, and liquid plating such as electroless plating. Separator and cell substrate that have been previously attached to the separator or cell by the phase growth method,
This is effective from the viewpoint of the adhesion strength between the solid electrolyte layer and the electrode layer. Because, the above-mentioned deposition method, compared with joining by sintering,
This is because the adhesion strength between different kinds of materials is excellent. Also,
In the fuel cell manufacturing method described above, the air electrode 3a is formed on the upper surface (flat surface) of the separator and the fuel electrode 4b is formed on the uppermost surface of the cell upper surface (flat surface).
And 3b) and the fuel electrode (4a and 4b)
The fuel cell is not limited to this combination, and may be exchanged with each other to manufacture a fuel cell.

In the fuel cell of the present invention, by combining the separator and the cell as described above, the separator and the cell are joined and laminated with the same material, which is a problem in the prior art. Cracks due to the thermal stress of the joint made of the phosphosilicate glass can be overcome. In addition, since the reducing gas and the oxidizing gas flow through a groove (gas flow path) surrounded only by the fuel electrode layer and the air electrode layer, the resistance between the electrodes due to the gas is suppressed from increasing,
That is, an increase in the internal resistance of the battery can be prevented. Furthermore,
Since the gas flow path is provided only on one side of the separator, the thickness of the separator is thinner than a structure having gas flow paths on both sides, and as a result, the output density of the SOFC can be improved. Furthermore, in the present invention, since the separator and the cell can be manufactured by substantially the same manufacturing process, the manufacturing process of the fuel cell can be simplified. In other words, manufacturing costs can be reduced.

[0029]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

EXAMPLE A (100) oriented single crystal silicon substrate (5 inch diameter, thickness 0.65 mm) having a resistivity of 10 to 11 Ωcm into which antimony was mixed was used. Was cut by a dicing saw into a square of 5 cm square so that each side was in the (110) direction. This square was subjected to a 10 minute immersion treatment in a mixed solution of water: hydrogen peroxide: ammonium hydroxide = 5: 1: 0.05 kept at 90 ° C., and then pure water was added to a 5% aqueous hydrofluoric acid solution for 1 minute. Immerse in water for 1 minute, take out, then dry with nitrogen gas injection, immediately with ultra-high vacuum specification, multiple targets
It was carried into a sputtering device. The outer peripheral portion of the film formation surface of the square silicon substrate housed in the substrate holder of the apparatus was covered with an Inconel mask to prevent the peripheral portion from being formed. The film formation area was set to be a 4 cm square portion at the center of the square substrate.

Using the above Si substrate, a separator and a cell plate were produced. 1) Preparation of Separator The substrate temperature of the above silicon substrate was raised to 500 ° C. using a radiant heater, and La0.8Sr0.2MnO
3 (hereinafter abbreviated as "LSM"), and a polycrystalline LSM having a thickness of about 5000
The film was grown. Next, a phosphorous silicate glass film (hereinafter, abbreviated as “PSG film”) having a thickness of about 5000 mm is deposited on both surfaces of the substrate by a normal pressure CVD method. Was transferred by a photolithography method, and only a transfer portion corresponding to a blank portion was removed by immersion treatment in a hydrofluoric acid-based etching solution. After the photoresist is removed by ashing, the substrate is immersed in an anisotropic etching solution of hydrazine hydrate kept at about 60 ° C., and as shown in FIG. 7, the silicon substrate is removed by etching according to the above pattern. Thus, a gas flow path was formed.
In this step, the time of immersion in the etching solution was shorter than the time of penetrating the substrate so that the etching was completed in the middle of the substrate. In this example, since the substrate was penetrated by the immersion time of about 8 hours, the immersion time of the etching solution during the production of the separator was within 8 hours. Subsequently, the silicon substrate was immersed in a hydrofluoric acid-based etchant to remove the protective PSG film. Through the above steps, an oxygen ion conductor thin film was manufactured. Next, a nickel oxide film having a thickness of about 5,000 ° was formed along the gas flow path on the substrate surface on which the gas flow path was formed by electron beam evaporation using a metal nickel vapor deposition source to produce a separator. .

2) Preparation of Cell Plate The above silicon substrate was heated to a temperature of 700 ° C. using a radiant heater, and was subjected to magnetron sputtering using a sintered target of LSM to a film thickness of about 5000 ° C. A crystalline LSM film was grown. Next, the substrate temperature was set to 600
The temperature was lowered to 10 ° C., and a 10 YSZ thin film having a thickness of about 2 μm was grown on the LSM film using a sintered target of 10 mol% yttria-added stabilized zirconia (hereinafter referred to as 10 YSZ). Next, the substrate temperature is lowered to 500 ° C.
Approximately 3000mm thick using a nickel metal target
Was grown. In this manner, the polycrystalline LSM film, 10YSZ
A film and a nickel oxide film were laminated. Next, a PSG film having a thickness of about 5000 mm is deposited on both surfaces of the substrate by a normal pressure CVD method, and then on the back surface of the silicon substrate (the back surface of the surface on which the 10YSZ film and the like are stacked) as shown in FIG. The pattern was transferred by photolithography, and only the transfer portion corresponding to the white portion was removed by immersion in a hydrofluoric acid-based etchant. Here, the reason why the area of the width of the etching pattern is narrow is to stop the etching in the middle of the substrate during the anisotropic etching. After the photoresist was removed by ashing, the substrate was immersed in an anisotropic etching solution of hydrazine hydrate kept at about 60 ° C. for about 8 hours, and as shown in FIG. Then, a small opening was formed in the substrate surface so that the laminated thin film was partially free standing. Next, the silicon substrate is immersed in a hydrofluoric acid-based etching solution,
The protective PSG film was removed. Subsequently, the surface where the laminated film was not formed was heated to a substrate temperature of 5 using a radiant heater.
The temperature was raised to 00 ° C., and a polycrystalline LSM film having a film thickness of about 3000 ° was grown along the gas flow path by magnetron sputtering using an LSM sintered target to produce a cell plate.

3) Lamination of Separator and Cell Plate A slurry of the same LSM air electrode material as the electrode material adhered to the flat surface of the separator prepared by the above procedure is applied to the flat surface electrode of the separator. Then, a slurry of the same nickel oxide fuel electrode material as the electrode material applied to the outermost surface of the flat surface of the cell plate is applied on the flat surface electrode of the cell plate, as shown in FIG. The flat main surface of the separator and the main surface of the cell where the gas flow path was formed, and the main surface of the separator where the gas flow path was formed and the flat main surface of the cell were stacked facing each other. After laminating them, they were fired at 600 ° C. in a firing furnace to produce a fuel cell stack, and a fuel cell was obtained by combining this with external extraction electrodes and a gas supply system.

(Comparative Example) As a conventional fuel cell, a fuel cell manufactured by using the technique introduced in the example of JP-A-8-64216 was used.

(Evaluation of Performance) Using the obtained fuel cell (two separators, one cell plate) and a conventional fuel cell,
Its performance was evaluated. The fuel cell was placed in an electric furnace, and a power generation test was performed at 700 ° C. using pure oxygen and pure hydrogen as raw material gases.

As shown in FIG. 13, as a result of the power generation test, the fuel cell of the example had an open electromotive force of 1.05 V and a maximum output of 0.45 W / cm ² . Although this result has almost the same output characteristics as the conventional fuel cell, the volume of the fuel cell of the present invention is about one-fourth (the difference in the thickness of the separator) as compared with the conventional fuel cell. Thus, it can be said that the output density of the fuel cell of the present invention is improved about three times.

Although the present invention has been described in detail with reference to preferred embodiments and examples, the present invention is not limited to these, and various modifications can be made within the scope of the present invention. For example, in the present invention, the shape and the like of the separator and the cell (cell plate) can be arbitrarily selected, and a fuel cell stack corresponding to a desired output can be manufactured. For convenience of explanation, one surface of each layer such as a substrate or an electrode layer is referred to as a “front surface” and “upper surface”, the other surface is referred to as a “back surface” and a “lower surface”, and accordingly, the electrode layer is referred to as an “upper electrode”. Although described as "lower electrode" and the like, these are equivalent elements, and it is needless to say that a configuration in which they are replaced with each other is also included in the scope of the present invention. Further, as the formation pattern of the through-hole shape, for example, a square, a rectangle, a polygon, a circle and the like can be appropriately selected.

[0038]

As described above, according to the present invention, the joint surface of the separator and the joint surface of the cell are made of the same material, and the gas flow passage (groove) is made of a fuel electrode material or an air electrode material. Since the structure is enclosed, the gas flow path is provided only on one side of the separator, and the separator and the cell are manufactured in the same process, cracks and the like due to thermal stress at the joint can be suppressed, and the internal resistance can be reduced. It is possible to provide a fuel cell separator capable of preventing an increase in power density, improving power density, and reducing manufacturing costs, a fuel cell using the same, and a fuel cell manufacturing method.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a fuel cell stack.

FIG. 2 is a cross-sectional view illustrating an example of a separator.

FIG. 3 is a cross-sectional view illustrating an example of a cell.

FIG. 4 is a schematic view showing an example of a conventional fuel cell stack.

FIG. 5 is a cross-sectional view showing an example of a conventional cell plate.

FIG. 6 is a schematic view showing a method for manufacturing a conventional fuel cell stack.

FIG. 7 is a schematic view illustrating an example of a method for manufacturing a separator.

FIG. 8 is a schematic view illustrating an example of a method for manufacturing a cell.

FIG. 9 is a schematic view showing a state where separators and cells are stacked.

FIG. 10 is a diagram illustrating an example of a gas flow path formed in a separator.

FIG. 11 is a diagram showing an example of a gas flow path and a through hole formed in a cell.

FIG. 12 is a diagram showing a cell used in the example.

FIG. 13 is a graph comparing output characteristics of a fuel cell as an example of the present invention and a conventional example.

[Explanation of symbols]

 1, 7 Conductive substrate (silicon substrate) 2, 8 Solid electrolyte layer (film) 3a, 3b, 9 Air electrode layer (film) 4a, 4b, 10 Fuel electrode layer (film) 11 Cell 12 Separator 13 Phosphosilicate glass 14 High-temperature compression bonding 15 Si bonding 16 Silver paste 20a, 20b Groove (gas flow path) 30 Through hole

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01M 8/24 H01M 8/24 E (72) Inventor Fumi Sato 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Mitsuru Yamanaka, Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture (72) Inventor Makoto Uchiyama 2nd Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture, Nissan Motor Co., Ltd. F-term (reference) in Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama 5H018 AA06 AS02 AS03 DD08 EE12 EE13 5H026 AA06 CC03 CX04 EE01

Claims (8)

[Claims] 1. A fuel cell separator inserted between cells, comprising a conductive substrate sandwiched between an upper electrode layer and a lower electrode layer.
It has a groove on the lower surface, and the material of the upper electrode layer is the same as the electrode material at the bottom of the cell laminated on the upper surface, and the material of the lower electrode layer is at the uppermost portion of the cell covered on the lower surface. A fuel cell separator characterized by being the same as the electrode material. 2. The fuel cell separator according to claim 1, wherein the upper electrode layer is a reduction electrode or an oxidation electrode, and the lower electrode layer is an oxidation electrode or a reduction electrode. 3. A fuel cell comprising a fuel cell stack comprising a combination of the fuel cell separator according to claim 1 and a cell. 4. The cell has a laminated structure in which a solid electrolyte layer and a conductive substrate are sandwiched between an upper electrode layer and a lower electrode layer, and the solid electrolyte layer has a conductive substrate on a lower surface thereof. The substrate is provided with a groove having a through hole in a part thereof, the upper electrode layer is laminated on the upper surface of the solid electrolyte layer,
4. The fuel cell according to claim 3, wherein the lower electrode layer covers the lower surface of the solid electrolyte layer from the entire lower surface of the conductive substrate via the through hole. 5. The fuel cell according to claim 4, wherein the upper electrode layer of the cell is a reduction electrode or an oxidation electrode, and the lower electrode layer is an oxidation electrode or a reduction electrode. 6. The material of the upper electrode layer of the cell is the same as the material of the lowermost electrode layer of the separator on the upper part of the cell, and the material of the lower electrode layer of the cell is the lower part of the cell. The fuel cell according to any one of claims 3 to 5, wherein the material is the same as the material of the uppermost electrode layer of the separator. 7. The fuel cell according to claim 3, wherein the material of the conductive substrate of the cell and the separator is silicon. 8. The method for manufacturing a fuel cell according to claim 3, wherein the separator and the cells are stacked on each other and fired at a time to form a fuel cell stack. A method for manufacturing a fuel cell, comprising: