JP2002329514A - Single cell for fuel cell and solid electrolyte fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized, high output and highly reliable single cell, cell plate, a stack for a fuel cell provided with these and a solid electrolyte fuel cell. SOLUTION: In the single cell for the fuel cell, a solid electrolyte layer 9 is arranged in a groove or a hole providing an air electrode layer 5 and a fuel electrode layer 6 on a substrate 10, an electrochemical reaction fluid is formed in a solid electrolyte layer interface, and a conductive material 3 is inserted in the substrate 10. Electron conductivity of the conductive material 3 is higher than electron conductivity of a forming material of the air electrode layer 5 and the fuel electrode layer 6. The solid electrolyte fuel cell uses the stack for the solid electrolyte fuel cell as a power generating element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid oxide fuel cell (SOFC) that uses a solid electrolyte to obtain electric energy by an electrochemical reaction, and more particularly, to a solid electrolyte sandwiched between electrode layers. The present invention relates to a single cell, a cell plate, a fuel cell stack including the same, and a solid oxide fuel cell.

[0002]

2. Description of the Related Art In recent years, fuel cells have attracted attention as a clean energy source capable of high energy conversion and friendly to the global environment, and applications as power sources for automobiles are being studied. 2. Description of the Related Art Solid oxide fuel cells (hereinafter abbreviated as “SOFC”) have been attracting attention as highly efficient fuel cells. However, since the electromotive force of a single fuel cell is as low as about 1 V, it is necessary to connect a plurality of single cells in series to form a stack in order to increase the voltage. Therefore, a stacking method is important. Further, when considering the application as a power source for automobiles, it is necessary to increase the output. One of the techniques for increasing the output of an SOFC is to reduce the thickness of a solid electrolyte or an electrode. JP-A-8-64
In the structure disclosed in Japanese Patent Application Publication No. 216 and the like, the current collecting function is insufficient, and a wiring structure for smoothly extracting a current is required.

[0003]

In the conventional fuel cell stack as described above, since the electrode portion also has a current collecting function, the thinner the electrode, the smaller the cross-sectional area of the conductive path, and the lower the electrical resistance. Becomes large. Further, if a separator or an interconnector is arranged between the cell elements in order to improve the current collection function, the ratio of the non-power generation elements in the fuel cell stack increases, and the output density decreases. Further, the conventional interconnector is exposed to both an oxidizing gas atmosphere and a reducing gas atmosphere at a high temperature, so high durability is required, and usable materials are limited. Furthermore, it is necessary to serialize the single cells in order to increase the voltage, but in a flat stack without a gas separator, it is extremely difficult to connect each single cell in series inside the stack. The external connection must be performed in series, and there are problems related to the complexity of the wiring structure and the increase in the number of components.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a highly reliable single cell that can be reduced in size and output.
An object of the present invention is to provide a cell plate, a stack for a fuel cell provided with these, and a solid oxide fuel cell.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that the above-mentioned problems can be solved by arranging a conductive material for collecting electricity in a predetermined shape. As a result, the present invention has been completed.

That is, the single cell for a fuel cell according to the present invention comprises a solid electrolyte layer sandwiched between an air electrode layer and a fuel electrode layer, which are arranged in grooves or holes provided in a conductive substrate or an insulating substrate. A single cell for a fuel cell, wherein the air electrode layer and the fuel electrode layer are electrically and mechanically joined to the solid electrolyte layer to form an electrochemical reaction field at the solid electrolyte layer interface; It is characterized in that a conductive material capable of collecting current from the reaction field and conducting current to the outside penetrates into a portion of the substrate in the extending direction and where the groove or hole does not exist.

In a preferred embodiment of the fuel cell unit cell according to the present invention, the electronic conductivity of the conductive material is equal to or higher than that of the material forming the air electrode layer and the fuel electrode layer. And

Further, the fuel cell plate according to the present invention provides the fuel cell unit cell in a two-dimensional and continuous manner in a direction substantially perpendicular to the laminating direction of the air electrode layer, the fuel electrode layer and the solid electrolyte layer. Alternatively, it is characterized by a plurality of intermittently joined ones.

Further, in the fuel cell stack according to the present invention, the fuel cell unit cell or the fuel cell cell plate may be disposed in a direction substantially the same as the lamination direction of the air electrode layer, the fuel electrode layer and the solid electrolyte layer. It is characterized in that it is two-dimensionally connected and integrated.

In a preferred embodiment of the fuel cell stack according to the present invention, the fuel cell single cell or the conductive material is provided with an insulating portion, and one or more single cells are provided on the air electrode layer side and the fuel electrode layer side. A current collecting portion for collecting the current.

Further, in another preferred embodiment of the fuel cell stack according to the present invention, the average area Sc of the cross section of the current collector and the average area Sr of the cross section of the reaction field satisfy Sc / Sr ≧ 10.
Is satisfied.

Still further, a solid oxide fuel cell according to the present invention is characterized in that the solid oxide fuel cell stack is constituted as a power generating element.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a single cell and a cell plate for a solid oxide fuel cell according to the present invention will be described in detail. In addition, in this specification, "%" shows a mass percentage unless otherwise specified. For convenience of description, one surface of each layer such as a single cell or an electrode layer is described as “upper surface, front surface”, and the other surface is described as “lower surface, back surface”, etc., but these are equivalent elements, and Needless to say, such a configuration is also included in the scope of the present invention. Further, the cell plate is a practical product form for promoting the integration of the single cells and increasing the output of the obtained fuel cell.

As described above, the single cell of the present invention comprises a solid electrolyte layer sandwiched between an air electrode layer and a fuel electrode layer, which is disposed on a substrate. Here, the substrate is, in particular, silicon (Si).
The present invention is not limited to the substrate, and any of a conductive substrate and an insulating substrate can be employed. For example, a glass substrate or a metal substrate can be used. Thus, the cost for the substrate can be reduced.
However, it is particularly desirable to use a Si substrate or a metal substrate. Further, the sandwiching body (the laminate of the air electrode layer, the solid electrolyte layer, and the fuel electrode layer) is arranged in a groove or a hole provided in the substrate. Thus, the electrode current collector is formed without using the dead space in the single cell and reducing the output density. Further, since the electrode current collector does not come into contact with the raw material gas (oxidizing gas and fuel gas), a material having low gas durability can be used. Further, a reaction field (power generation unit) formed by contact of the raw material gas is fixed in a desired form. The grooves and holes can be formed into various shapes in consideration of the output when the fuel cell is used, the source gas flow path, and the like, and the depths of the grooves and holes are not particularly limited.

The constituent materials of the air electrode layer and the fuel electrode layer include, for example, nickel (N
i), copper (Cu) and cermets thereof can be used, and LSM, LSC and Pt can be used as an air electrode layer.

Further, the solid electrolyte layer is necessary for exhibiting a power generation function, and is a conventionally known material having oxygen ion conductivity, for example, neodymium oxide (Nd
₂ O _3), samarium oxide _{(Sm 2 O} 3), yttria _(Y 2 _{O 3)} and stabilized zirconia and the solid solution and gadolinium oxide _(Gd 2 _{O 3),} ceria (CeO ₂₎ solid solution, bismuth oxide And LaGaO ₃ can be used, but is not limited thereto.

Further, in the single cell of the present invention, the air electrode layer and the fuel electrode layer are electrically and mechanically joined to the solid electrolyte layer to form an electrochemical reaction field at the solid electrolyte layer interface. In addition, a conductive material capable of collecting current from the reaction field and conducting current to the outside penetrates into a portion of the substrate in the extending direction and where the groove or hole does not exist. And Thus, the DC resistance of the stack can be reduced, and the single cells can be connected in series in the stack. Further, since the conductive material is not exposed to gas, even a material having low durability can be used. Further, by using a material having high strength as the conductive material, mechanical strength can be improved.

Examples of the conductive material include lanthanum-strontium-manganese (La-Sr-Mn) composite oxide and lanthanum-strontium-cobalt (La).
-Sr-Co) composite oxide, lanthanum chromite, silver (Ag), nickel (Ni), copper (Cu), platinum (P
Alloys comprising metals according to t) or iron (Fe), and any combination thereof, and / or stainless steel can be used. As described above, by selecting a material that can reduce the difference in thermal expansion coefficient between the other portions, the thermal shock when the stack is formed can be reduced, and the temperature of the fuel cell stack can be increased at a high speed. In addition, the power collection function is high,
A stable electrode layer current collector can be formed even at a high temperature.
It is also effective to use a heating element such as a nickel-chromium alloy as the conductive material. In this case, it can be used as a starting heat source for a stack or the like by energization.

Further, it is preferable that the electronic conductivity of the conductive material is equal to or higher than the electron conductivity of the material forming the air electrode layer and the fuel electrode layer. Accordingly, the resistance of each electrode layer current collector is made sufficiently small, and current collection is easily performed. Further, when the cell plate is formed, the temperature distribution in the cell plate can be made uniform, and the thermal durability of the stack can be improved.

The cell plate for a fuel cell according to the present invention is characterized in that the above-mentioned single cell is two-dimensionally and continuously or intermittently arranged in a direction substantially perpendicular to the laminating direction of the air electrode layer, the fuel electrode layer and the solid electrolyte layer. And a plurality of them. In this case, the balance between the electric resistance and the power generation output can be adjusted by appropriately changing the number of single cells handled by the conductive material, which is effective. Here, the case where such a cell plate is formed by intermittently joining the unit cells means that the unit plate is a unit plate obtained by combining the unit cells of the present invention in which the conductive material is removed from the unit cells. In other words, a configuration is adopted in which a conductive material is provided for each of two or more single cell units.

Next, the stack for a solid oxide fuel cell according to the present invention will be described. Such a stack for a solid oxide fuel cell comprises two or more two-dimensionally connected single cells or cell plates for the fuel cell described above, which are two-dimensionally connected in the same direction as the lamination direction of the air electrode layer, the fuel electrode layer and the solid electrolyte layer. Become
When such a stack is used as a power generation element, a fuel cell having excellent output characteristics (suitable for an automobile power supply) can be obtained.

Further, an insulating portion is provided on the single cell for a fuel cell or the conductive material to form a current collecting portion for collecting current on the air electrode layer side and the fuel electrode layer side for one or more single cells. Is preferred. In other words, the reaction field responsible for the electrode reaction and the current collecting part responsible for the current transport can be separated for each desired unit, the DC resistance of the stack can be reduced, and the single cells can be easily connected in series. The insulating portions can be provided so as to be connected in series. In addition, examples of the insulator constituting the insulating portion include alumina, SiN, and glass. Note that, in the solid oxide fuel cell stack of the present invention, it is desirable to insulate each electrode layer from the conductive material.

Further, the average area Sc of the cross section of the current collector is described.
Is preferably larger than the average area Sr of the cross section of the reaction field. Specifically, the average area Sc of the cross section of the current collector and the average area Sr of the cross section of the reaction field are S
It is preferable that the relationship of c / Sr ≧ 10 is satisfied, that is, the cross-sectional area of the current collecting unit is at least 10 times the cross-sectional area of the reaction field responsible for current collection. In this case, the resistance of the electrode layer current collector can be sufficiently reduced, and current collection can be performed smoothly.

Next, the solid oxide fuel cell of the present invention will be described. Such a fuel cell is obtained by configuring the solid oxide fuel cell stack described above as a power generation element. As a result, since the fuel cell is constituted by a stack in which a conductive material is penetrated, the conductive material can be used as an interconnector (electrically conductive path), and it is easy to make the fuel cell thinner and smaller.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings by way of examples and comparative examples, but the present invention is not limited to these examples.

In Examples 1 and 2, a plurality of unit cell plates A and B were stacked to produce a solid oxide fuel cell, and its performance was evaluated.

Example 1 1) Fabrication of Substrate A (1) having a resistivity of 10 to 11 Ωcm mixed with antimony was used.
00) Oriented single crystal silicon substrate (5 inch diameter, thickness 1.
0 mm), using a mirror-polished surface on one side,
This was cut with a dicing saw into a square of 5 cm square so that each side was in the (110) direction. This square was kept at 90 ° C. water: hydrogen peroxide: ammonium hydroxide =
After immersion treatment in a 5: 1: 0.05 mixed solution for 10 minutes, immersion in a 5% aqueous hydrofluoric acid solution for 1 minute and immersion in pure water for 1 minute, and then taking out, followed by drying with nitrogen gas injection, and immediately It was carried into a vacuum specification, multiple target sputtering system. 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. A cell plate was produced using the Si substrate.

2) Preparation of single cell plate A The above silicon substrate was heated to 700 ° C. using a radiant heater, and oxidized to a thickness of about 5000 ° by RF sputtering using a metal nickel target. A nickel film was grown. Next, the temperature of the substrate was lowered to 600 ° C., and a 10 mol% yttria-added stabilized zirconia (hereinafter, referred to as “10YSZ”) sintered target was used to form a 10 YSZ film having a thickness of about 2 μm on the nickel oxide film.
A thin film was grown. Next, the substrate temperature is lowered to 500 ° C., and a film thickness of about 30
A polycrystalline LSM film of 00 ° was grown. In this manner, the nickel oxide film, 10
A YSZ film and a polycrystalline LSM film were laminated.

Next, a PSG (phosphosilicate glass) film having a thickness of about 5000 mm is deposited on both surfaces of the substrate by a normal pressure CVD method, and then the back surface of the silicon substrate (the back surface of the surface on which the 10YSZ film and the like are laminated). Then, the pattern shown in FIG. 1 was transferred by photolithography, and only the transfer portion corresponding to the white portion in FIG. 1 was removed by immersion in a hydrofluoric acid-based etching solution. 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 the silicon substrate was made to conform to the above pattern as shown in FIG. Then, a small opening 2 is formed in the substrate surface so that the laminated thin film is partially free standing. Also, the groove 3 serving as an electrode current collector is formed simultaneously between the small openings. This groove does not penetrate the substrate in the thickness direction. Next, the silicon substrate is immersed in a hydrofluoric acid-based etching solution,
The protection PSG film 4 was removed. Subsequently, the substrate temperature was raised to 500 ° C. using a radiant heater on the surface on which the above-mentioned laminated film was not formed, and along a gas flow path by RF sputtering using a sintered target of metallic nickel. Then, a nickel oxide film having a thickness of about 3000 ° was grown, and then a metal nickel paste was filled in a groove serving as an electrode current collector and dried to produce a unit cell plate A. The size of each element is 1.0 mm × 1.0 mm for the opening 2, and the interval between the openings 2 is 1.
0 mm, the width of the groove is 0.8 mm at the longest part (the bottom side of the triangle when viewed in cross section), and the depth of the groove is 0.7 mm.

3) Preparation of Single Cell Plate B The above silicon substrate was heated to 700 ° C. using a radiant heater, and was subjected to RF sputtering using an LSM sintered target to a film thickness of about 5000 ° C. Polycrystalline L
An SM film was grown. Next, the substrate temperature was lowered to 600 ° C., and a 10 YSZ thin film having a thickness of about 2 μm was grown on the LSM film by using a sintered target of 10 mol% yttria-added stabilized zirconia (hereinafter referred to as 10 YSZ). . Next, the substrate temperature was lowered to 500 ° C., and a nickel oxide film having a thickness of about 3000 ° was grown using a metal nickel target. Thus, a polycrystalline LSM film, a 10YSZ film, and a nickel oxide film were sequentially laminated on one surface of the silicon substrate.

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 the back surface of the silicon substrate (the back surface of the surface on which the 10YSZ film and the like are laminated).
Then, the pattern shown in FIG. 1 was transferred by photolithography, and only the transfer portion corresponding to the white portion in the figure was removed by immersion in a hydrofluoric acid-based etching solution. 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 is removed by ashing, the substrate is 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 2 is formed in the substrate surface so that the laminated thin film is partially free standing. Also, the groove 3 serving as an electrode current collector is formed simultaneously between the small openings. This groove does not penetrate the substrate in the thickness direction. Next, the silicon substrate was immersed in a hydrofluoric acid-based etching solution to remove the protective PSG film 4. Subsequently, the substrate temperature was raised to 500 ° C. using a radiant heater on the surface on which the laminated film was not formed, and along a gas flow path by RF sputtering using a sintered target of LSM. Polycrystalline LS with a thickness of about 3000mm
An M film was grown, and then a metal nickel paste was filled in a groove serving as an electrode current collector and dried to prepare a unit cell plate B. The size of each element is 1.0 mm x 1.0 for the opening.
mm, the interval between the openings is 1.0 mm, the width of the groove is 0.8 mm at the longest part (the bottom of the triangle when viewed in cross section), and the depth of the groove is 0.7 mm.

4) Fabrication of Solid Oxide Fuel Cell (Lamination of Unit Cell Plates) A slurry of the same LSM air electrode material as the electrode material adhered to the flat surface of the unit cell plate A manufactured by the above procedure Is applied onto the flat surface electrode of the unit cell plate A, and then a slurry of the same nickel oxide fuel electrode material as the electrode material adhered to the outermost surface of the flat surface of the unit cell plate is applied to the unit cell plate. Was applied on the flat surface electrode, and as shown in FIG. 2, each unit cell plate was laminated so as to face each other. After laminating them, they were batch fired at 600 ° C. in a firing furnace to produce a fuel cell.

[Evaluation of Performance] The above-mentioned unit cell plate A2 was placed in an electric furnace.
A fuel cell in which the fuel cell and the single cell plate B are stacked is installed, and 70
The temperature was raised to 0 ° C., and an AC impedance measurement and a power generation test were performed using pure oxygen and pure hydrogen as raw material gases. As a result of the AC impedance measurement, the direct current resistance was 0.3Ω when the electrode layer collector was not formed, whereas the direct resistance was as low as 0.03Ω when manufactured in this example. . In addition, as a result of the power generation test, the open electromotive force 1.
05 V and a maximum output of 0.8 W / cm ² .

(Embodiment 2) FIG. 4 shows the manufacturing process of this embodiment. FIG. 3 shows a cross-sectional view and a plan view of a part of the cell plate. Using high silicate glass having a thickness of 0.5 mm and a square of 5 cm square as the substrate 11, six holes of 2 mmφ and a groove (size) to be an electrode current collector were processed. (A) Next, a silane coupling material is applied to the surface of the Si substrate as the temporary substrate 12 and placed on the upper surface of the substrate 11,
And heat bonded. (B) YSZ is formed as an electrolyte layer 13 to a thickness of 1 μm as an electrolyte layer 13 on the opening in a desired pattern from the lower surface of the substrate by using an evaporation mask by an RF sputtering method. (C) Subsequently, the LSM is applied to the lower electrode layer 14 by 5 μm by RF sputtering so that the lower electrode layer 14 is directly adhered to the electrolyte layer from the lower surface of the substrate.
m is formed. (D) The temporary substrate is peeled off using a hydrofluoric acid-based etchant. (E) Ni metal paste is filled in a groove to be an electrode current collector of the substrate and dried to form an electrode current collector 15. (F) YSZ and Ni are formed as the upper electrode layer 16 from the upper surface of the substrate by 5 μm by a two-source sputtering method. (G) The unit cell plate thus prepared was referred to as a unit cell plate A.

In the above manufacturing process, the step (d)
The lower electrode layer is formed by sputtering YSZ and Ni by two-source sputtering.
A cell plate having an upper electrode layer of 5 μm formed by RF sputtering on the upper electrode layer in step (g) was
And

[Evaluation of Performance] In the same manner as in Example 1, the power generation characteristics at 500 ° C. were evaluated using a fuel cell in which the two unit cells A and one unit cell B were stacked. The open-circuit voltage was 0.92 V, and the output was 0.22 W / cm ² .

Although the present invention has been described in detail with reference to the embodiments, 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 single cell and the cell plate can be arbitrarily selected, and a solid oxide fuel cell according to the desired output can be manufactured. In addition, the conductive material can penetrate not only in the direction in which the substrate extends but also in the direction in which the electrode layers are stacked. Desired output control is possible by combining and connecting these conductive materials. A simple fuel cell can be obtained.

[0038]

As described above, according to the present invention, since the conductive material for collecting current is arranged in a predetermined shape, it is possible to reduce the size, increase the output, and obtain a highly reliable unit. It is possible to provide a cell, a cell plate, a fuel cell stack including the same, and a solid oxide fuel cell.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a substrate.

FIG. 2 is a cross-sectional view illustrating an example of a fuel cell stack.

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

FIG. 4 is a cross-sectional view illustrating an example of a manufacturing process of the cell plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas flow path (part which becomes a gas flow path) 2 Cell hole (part which becomes a cell hole) 3 Groove (current collection part) (part which becomes a groove (current collection part)) 4 Unetched part (protective PSG film) 5 Air electrode 6 Fuel electrode 7 Air electrode reaction part 8 Fuel electrode reaction part 9 Electrolyte 10, 11 Substrate (glass substrate) 12 Temporary substrate 13 Electrolyte layer 14 Lower electrode layer 15 Electrode collector 16 Upper electrode layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tadashi Shibata Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture (72) Inventor Masaharu Hatano 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa, Nissan Motor Co. 72) Inventor Naoki Hara 2 Takaracho, Kanagawa-ku, Yokohama City, Kanagawa Prefecture Nissan Motor Co., Ltd. (72) Inventor Fumi Sato 2 Takaracho, Kanagawa-ku, Yokohama City, Kanagawa Prefecture Nissan Motor Co., Ltd. (72) Inventor Mitsugu Yamanaka Kanagawa Prefecture Nissan Motor Co., Ltd., 2nd, Takaracho, Kanagawa-ku, Yokohama-shi (72) Inventor Makoto Uchiyama 2nd, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. F-term (reference) 5H026 AA06 CC03 CV06 EE08 EE13 HH02

Claims (9)

[Claims] 1. A single cell for a fuel cell comprising a solid electrolyte layer sandwiched between an air electrode layer and a fuel electrode layer and arranged in a groove or a hole provided in a conductive substrate or an insulating substrate, The air electrode layer and the fuel electrode layer are electrically and mechanically joined to the solid electrolyte layer to form an electrochemical reaction field at the solid electrolyte layer interface. A unit cell for a fuel cell, wherein a conductive material capable of collecting current from the reaction field and conducting current to the outside penetrates into a portion where no hole exists. 2. The unit cell for a fuel cell according to claim 1, wherein the electronic conductivity of the conductive material is equal to or higher than the electronic conductivity of the material forming the air electrode layer and the fuel electrode layer. 3. The method according to claim 1, wherein the conductive material is at least one selected from the group consisting of lanthanum-strontium-manganese composite oxide, lanthanum-strontium-cobalt composite oxide, lanthanum chromite, silver, nickel, copper, platinum and iron. 3. The unit cell for a fuel cell according to claim 1, wherein the unit cell is made of an alloy containing any one of the above and / or stainless steel. 4. The fuel cell unit according to claim 1, wherein the single cell for a fuel cell is two-dimensionally arranged in a direction substantially perpendicular to a laminating direction of the air electrode layer, the fuel electrode layer and the solid electrolyte layer. A cell plate for a fuel cell, wherein a plurality of cells are continuously or intermittently joined. 5. The fuel cell unit cell according to any one of claims 1 to 3, or the fuel cell panel according to claim 5, wherein the air electrode layer, the fuel electrode layer, and the solid electrolyte layer are provided. A solid oxide fuel cell stack comprising a plurality of two-dimensionally connected and integrated two-dimensionally in substantially the same direction as the lamination direction. 6. An insulating portion is provided on the fuel cell single cell or the conductive material, and a current collecting portion for collecting power on the air electrode layer side and the fuel electrode layer side is formed for each of one or more single cells. The solid oxide fuel cell stack according to claim 5, wherein 7. An average area Sc of a cross section of the current collector is:
7. The stack for a solid oxide fuel cell according to claim 6, wherein the average area of the cross section of the reaction field is larger than Sr. 8. The average area Sc of the cross section of the current collector and the average area Sr of the cross section of the reaction field are Sc / Sr ≧ 1.
The stack for a solid oxide fuel cell according to claim 7, wherein a relationship of 0 is satisfied. 9. A solid oxide fuel cell comprising the stack for a solid oxide fuel cell according to claim 5 as a power generating element.