JP2958782B2 - Method for manufacturing flat solid electrolyte fuel cell - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a flat solid electrolyte fuel cell.

[Conventional technology and its problems]

A plate-type solid electrolyte fuel cell usually has a structure in which unit cells composed of an air electrode, a solid electrolyte, a fuel electrode, and a separator are stacked.

In order to manufacture a flat solid electrolyte fuel cell using the four types of components constituting the unit cell, in the simplest case, as shown in FIG.
According to the first method of firing, it is preferable to use a separator or an electrode plate as a support, and to improve the denseness of the solid electrolyte and the thin film of the separator or to make the manufacturing process consistent, A second method of manufacturing a battery by sequentially laminating thin films by a method such as physical vapor deposition such as thermal spraying or sputtering, or a chemical vapor deposition, or a third method of stacking and sintering green sheets of the respective components together is known. ing. These conventional manufacturing methods have the following problems.

In the first method by firing, the thickness of the solid electrolyte and the separator needs to be about 100 μm or more in order to ensure the denseness, and the internal resistance of the battery is large because the resistivity of these components is large. There is a disadvantage that it becomes. The third method using integral sintering has a drawback that it is difficult to control the shrinkage of each component during calcination and during calcination. In addition, it is difficult to fire a large-area product due to warpage due to shrinkage.

In the second method by plasma spraying, a raw material powder having a particle diameter of several tens of microns is often used in order to stably supply the raw material powder into a plasma frame. Has a low thermal conductivity,
Without sufficiently melting into the interior of the particles, the raw material powder
It is difficult to obtain a sufficient density to reach the deposition supporting plate composed of the electrode plate or the separator plate.

The chemical vapor deposition in the second method is, for example, a method disclosed in Japanese Patent Application Laid-Open No. 61-153280, and is used for manufacturing a cylindrical solid electrolyte fuel cell. According to this method, a very dense solid electrolyte and a thin film of a separator can be formed, and a good solid electrolyte-electrode interface can be formed, but the growth rate of the thin film is low. Is the problem. Further, in the manufacturing process of the cylindrical battery, a masking process is required, and there is a disadvantage that the manufacturing process is too complicated.

In the physical vapor deposition such as sputtering used in the second method, a sufficiently dense thin film can be formed, but there is a problem that the growth rate is lower than that in the case of chemical vapor deposition.

In the second method, plasma spraying, physical vapor deposition,
When a battery is formed by sequentially laminating constituent thin films on a support by chemical vapor deposition or the like, there are disadvantages that the number of quality control steps increases and the yield of products decreases.

JP-A-63-166154 discloses an interconnector, an oxygen electrode, a fuel electrode, and a flat solid electrolyte fuel cell in which cells are formed by sequentially stacking respective flat plates of an interconnector, an oxygen electrode, a solid electrolyte, and a fuel electrode. A flat solid electrolyte fuel cell characterized in that any one or any two of the above is combined to increase the wall thickness to have a function of a support.

According to the cell disclosed in the above-mentioned publication, although the problem of strength is temporarily solved as compared with the case where the cell is constituted only by a thin film, the claims in the above-mentioned publication disclose “combining any two”. In addition, the thickness is increased. "In the same gazette, page 4, lower left column, lines 6 to 8 describe" a combination of two or more types of interconnector 4, oxygen electrode 1, and fuel electrode 3 ". However, there is no description of the specific contents of the combination, but only a method of merely sequentially stacking the cell components. Therefore, it is difficult to control the shrinkage ratio of each component at the time of firing, the number of quality control steps is large, and the yield of products is low.

[Object of the invention]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and is directed to the manufacture of a flat solid electrolyte fuel cell using physical vapor deposition or chemical vapor deposition as a vapor phase method capable of forming a dense solid electrolyte and a thin film of a separator. In the method, it is difficult to control the shrinkage rate of each component during firing by forming in advance two types of integrated parts by a specific combination of components of the unit cell by forming, firing and vapor deposition. It is an object of the present invention to provide a method of manufacturing a flat solid electrolyte fuel cell which solves the problems in the prior art, reduces the number of quality control steps, improves product yield, and can simplify the manufacturing steps. .

[Means and actions for solving the problems]

The present invention provides, in a first aspect, a method for producing a flat solid electrolyte fuel cell comprising a separator, an air electrode, a solid electrolyte, and a fuel electrode, the method comprising:
An integrated portion A-1 formed by depositing a solid electrolyte on the smooth surface of the fired thick film air electrode to form a single layer of the thin film and a gas passage, and a formed and fired thickness A separator is deposited on the smooth surface of the fuel electrode of the membrane, and an integrated portion B-1 obtained by integrally forming a thin film of the separator is directly opposed to the air electrode and the fuel electrode, and the solid electrolyte membrane is sandwiched therebetween. Another object of the present invention is to provide a method of manufacturing a flat solid electrolyte fuel cell, which comprises stacking unit cells in such a shape and stacking the unit cells.

According to a second aspect of the present invention, in the method for producing a flat solid electrolyte fuel cell comprising a separator, an air electrode, a solid electrolyte, and a fuel electrode, the separator is deposited on a smooth surface of the air electrode to further form a thin film thereof. An integrated part A-2 formed only integrally and an integrated part B-2 formed by depositing a solid electrolyte on the smooth surface of the fuel electrode to form a thin film as a single layer, An air electrode and a fuel electrode are directly opposed to each other so as to sandwich a solid electrolyte membrane so as to sandwich the solid electrolyte membrane to form a unit cell. To provide.

According to a third aspect of the present invention, in the manufacturing method according to the first aspect of the present invention, a thin film made of the same raw material as the fuel electrode is further formed on the surface of the solid electrolyte thin film of the integrated portion A-1. A method of manufacturing a flat solid electrolyte fuel cell, characterized by firing to form an integrated portion A-3.

The present invention, in a fourth aspect, is the production method according to the second aspect of the present invention, further comprising forming a thin film made of the same raw material as the air electrode on the surface of the solid electrolyte thin film of the integrated portion B-2. The present invention provides a method of manufacturing a flat solid electrolyte fuel cell, characterized by firing to form an integrated portion A-4.

A flat solid electrolyte fuel cell (hereinafter, may be simply referred to as a battery) in the present invention is formed by stacking unit cells each including an air electrode, a solid electrolyte, a fuel electrode, and a separator.

As the fuel electrode constituting the unit cell of the present invention, a conventionally known fuel electrode can be used, but it is stable under a high-temperature reducing atmosphere, has high electron conductivity, and allows passage of gaseous reactants and products. It is required that the thermal expansion coefficient difference between the solid electrolyte and the solid electrolyte be small, for example, it is possible to use a porous body of nickel-zirconia cermet, and specifically, the particle size is 20 microns or less. Of metallic nickel and yttria-stabilized zirconia powder in a weight ratio of 5: 5 to 7: 3 with an organic binder, solvent, plasticizer, dispersant, and defoamer. Get the slurry,
After injection molding, it is fired in a reducing atmosphere to form a thick-film porous plate having a groove functioning as a fuel gas passage and having a thickness of about 3 mm. The obtained porous fuel electrode is polished on both sides in order to improve the surface accuracy. Although a method of using nickel oxide as a nickel component and reducing it in the operating atmosphere of a battery is also conceivable, a method using metallic nickel is preferable because cracks may occur in the electrode plate due to a volume change during reduction.

The fuel electrode of the present invention is a thick film and also has a function as a support.

The fuel gas passage of the fuel electrode of the present invention is generally the same as shown in FIGS. 1a and 1b.
Although it is formed as a groove as shown in the figure, as shown in FIG. 2, it may be formed as a through hole extending from one end surface of the electrode plate to the other end surface facing the electrode plate. The electrode plate having the structure shown in FIG. 2 has a smooth surface, so that it can have a high contact point density and a low contact resistance when laminated with other battery components, but have a larger thickness. It must be formed, and fabrication is more difficult.

The air electrode constituting the unit cell of the present invention requires the same requirements as for the fuel electrode, and is a known method, specifically, by a method similar to the fuel electrode, for example, doped with strontium. Lantern Manganite (La _0.05 S
r _0.15 MnO ₃ ) is used as a raw material to form a grooved thick-film porous plate with a thickness of about 3 mm. The cathode is a thick film,
Like the above-mentioned fuel electrode, it has a gas passage and also has a function as a support.

As the solid electrolyte constituting the unit cell of the present invention, a known solid electrolyte can be appropriately selected and used.However, since fuel and air flow on both sides of the solid electrolyte through itself, the solid electrolyte is so dense that gas does not permeate. It must be formed as a thin film because it has a resistivity approximately three orders of magnitude higher than that of the electrode material and can cause an increase in internal resistance.

The solid electrolyte requires high oxide ion conductivity, and for example, stabilized zirconia to which yttria or the like is added can be used.

The separator constituting the unit cell of the present invention is a component necessary for separating air and fuel, and must be stable under a high-temperature oxidizing and reducing atmosphere of about 1000 ° C. and have high electron conductivity. Is required, for example, lanthanum chromite to which magnesium or the like is added can be used.

According to the first aspect of the method of the present invention, the solid electrolyte is provided on a smooth surface of the air electrode of the thick film which has a gas passage formed by grooving or drilling of a through hole, and which is formed and fired in advance. An integrated part A-1 is obtained by depositing the thin film by chemical vapor deposition or physical vapor deposition, preferably by chemical vapor deposition, and forming only one thin film integrally with the air electrode. On the other hand, having a gas passage formed in the same manner as the air electrode, a separator is deposited by chemical vapor deposition or physical vapor deposition, preferably by chemical vapor deposition, on the smooth surface of the thick-film fuel electrode formed and fired in advance, and the thin film is formed. Only one layer is formed integrally with the fuel electrode to form an integrated part B-
Get 1. The integrated portion A-1 and the integrated portion B-1 obtained in this manner are arranged such that the air electrode and the fuel electrode do not directly face each other and the gas passages are orthogonal, parallel or opposite to each other, preferably orthogonal. The cells are stacked in such a manner as to sandwich the solid electrolyte membrane in the direction in which the cells are formed, and the cells are stacked to obtain the battery of the present invention.

According to a second aspect of the method of the present invention, the separator is formed by chemical vapor deposition or physical vapor deposition on the smooth surface of the air electrode to form a single thin film integrally with the air electrode to form an integrated portion A-2. Get. On the other hand, a solid electrolyte is chemically vapor-deposited or physically vapor-deposited on the smooth surface of the fuel electrode, and a single thin film is formed integrally with the fuel electrode to obtain an integrated portion B-2. The integrated part A-2 and the integrated part B thus obtained
-2 in a direction in which the air electrode and the fuel electrode do not directly face each other and the gas passages are in a direction orthogonal, parallel or opposite to each other, preferably in a direction orthogonal to each other and sandwich the solid electrolyte membrane to form a single unit. A battery is formed and laminated to obtain the battery of the present invention.

According to the above-described first and second aspects of the method of the present invention, only one thin film is formed on the air electrode or the fuel electrode which is a thick film and has a function as a support. It has the effect of avoiding complication and improving the product yield. The yield of the product, for example in the case of forming continuously a plurality of times a thin film components on one support, the average yield per one r, when a series of consecutive formation number and n, r ⁿ And exponentially decreases, but according to the method of the present invention,
r, and the product yield can be improved.

According to a third aspect of the method of the present invention, the first aspect of the method of the present invention is provided.
A slurry made of the same raw material as that of the fuel electrode is further applied to the surface of the solid electrolyte thin film of the integrated portion A-1 obtained in the above embodiment, and the thin film is formed and fired to obtain the integrated portion A-3. The integrated portion A-3 thus obtained and the integrated portion B-1 obtained in the first embodiment of the method of the present invention are brought into contact with a thick-film fuel electrode and a thin-film fuel electrode. Unit cells are formed by stacking them in the same manner as in the first embodiment, and the unit cells are stacked to obtain the battery of the present invention.

According to the fourth aspect of the method of the present invention, a slurry made of the same raw material as the air electrode is further applied to the surface of the solid electrolyte thin film of the integrated portion B-2 obtained in the second aspect of the method of the present invention. Then, the thin film is formed and fired to obtain an integrated portion A-4. The integrated part A- thus obtained
4 and the integrated portion A-2 obtained in the second embodiment of the method of the present invention are overlapped with each other in the same manner as in the second embodiment so that the thick-film air electrode and the thin-film air electrode are brought into contact with each other. A battery is formed and laminated to obtain the battery of the present invention.

According to the above-described third and fourth aspects of the present invention, the electromotive reaction can proceed smoothly by forming an integrated portion formed by further forming and firing a thin film of the fuel electrode or the air electrode. A good solid electrolyte / electrode interface structure can be formed.

〔Example〕

Example 1 The method of the present invention will be specifically described with reference to FIG. 1a. No.
In FIG. 1a, a strontium-doped lanthanum manganite is used as a raw material, and a porous plate with a groove of about 3 mm in thickness is formed. On a smooth surface of the fired air electrode 1, zirconium and yttrium chloride are used as a raw material. A dense film 2 of a solid electrolyte (yttria-stabilized zirconia) having a thickness of about 50 microns is formed by a chemical vapor deposition method to obtain an integrated portion A-1.

On the other hand, metallic nickel having a particle size of 20 microns or less and yttria-stabilized zirconia powder in a weight ratio of 5: 5 to 7: 3, together with an organic binder, a solvent, a plasticizer, a dispersant, and an antifoaming agent. After mixing well to obtain a viscous slurry, which is injection-molded, fired in a reducing atmosphere, the fuel is formed as a thick-film porous plate with a thickness of about 3 mm with grooves functioning as fuel gas passages. On the smooth surface of pole 3, lanthanum, chromium,
By a chemical vapor deposition method using magnesium chloride as a raw material, a separator 4 (lanthanum chromite doped with magnesium: LaCr _1-x Mg _x O ₃₀ <x
An integrated part B-1 is obtained by forming a dense film of <0.15).
The integrated part A-1 and the integrated part B-1 thus obtained are overlapped as shown in FIG. 1a to form a unit cell, and the unit cell is laminated to obtain the battery of the present invention. Can be

Example 2 An integrated part A- obtained in the same manner as in Example 1 except that the solid electrolyte 2 and the separator 4 of Example 1 were replaced.
2 and the integrated portion B-2 were overlapped in the same manner as in Example 1 to form a unit cell, and this was laminated to obtain the battery of the present invention.

Example 3 In FIG. 1b, the surface of the solid electrolyte 2 of the integrated portion A-1 composed of the air electrode 1 and the solid electrolyte 2 obtained in the same manner as in Example 1 was further the same as the fuel electrode 3 in Example 1. Is applied with a slurry made of the same raw material as the fuel electrode 3b,
The thin film 3a is formed and fired to obtain an integrated portion A-3.
The integrated part A-3 obtained in this way and Example 1
In FIG. 1b, a unit cell is formed by stacking the fuel electrode 3b and the separator 4 in the same manner as in Example 1 to form a unit cell. The battery of the present invention is obtained.

Example 4 In FIG. 1b, as in Example 3, an integrated part A-4 obtained by firing a thin film 3a made of the same material as the air electrode 3b on the surface of the solid electrolyte 2 of Example 2
And a unit cell, which is the same as the integrated portion A-2 in Example 2, but is composed of the air electrode 3b and the separator 4 is overlapped in the same manner as in Example 1 to form a unit cell. The battery of the present invention is obtained.

〔The invention's effect〕

According to the present invention, firstly, there is provided a flat solid electrolyte fuel cell which can solve the problem of the prior art that it is difficult to control the shrinkage ratio of the constituent elements constituting the unit cell during firing.

Secondly, according to the present invention, there is provided a method for manufacturing a flat solid electrolyte fuel cell which can reduce the number of quality control steps and improve product yield.

Thirdly, according to the present invention, there is provided a method of manufacturing a flat solid electrolyte fuel cell capable of easily and safely forming unit cells and stacking the formed unit cells.

[Brief description of the drawings]

FIG. 1a is an exploded perspective view for explaining the first or second aspect of the present invention, and FIG. 1b is an exploded perspective view for explaining the third or fourth aspect of the present invention. FIG. 2 shows one of the gas passages of the air electrode or the fuel electrode in the present invention.
FIG. 3 is a perspective view for explaining an example, and FIG. 3 is an exploded view for explaining a stacking step of each component of the battery in a conventional method for manufacturing a flat solid electrolyte fuel cell. Description of reference numerals: 1 ... air electrode or fuel electrode, 2 ... solid electrolyte or separator, 3.3a / 3b ... fuel electrode or air electrode, 4 ...
Separator or solid electrolyte, 11 ... gas passage.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-166154 (JP, A) JP-A-61-153280 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01M 8/00-8/24

Claims (4)

(57) [Claims] 1. A method for manufacturing a flat solid electrolyte fuel cell comprising a separator, an air electrode, a solid electrolyte and a fuel electrode, comprising a gas passage, a solid film formed on a smooth surface of a thick-film air electrode formed and fired. It has an integrated portion A-1 formed by depositing an electrolyte to form a single layer of the thin film and a gas passage, and a separator is deposited on the smooth surface of the formed and fired thick film fuel electrode. A unit cell is formed by superimposing an integrated portion B-1 obtained by integrally forming a single layer of the thin film such that the air electrode and the fuel electrode are directly opposed to each other and sandwich the solid electrolyte membrane slightly. A method for manufacturing a flat solid electrolyte fuel cell, comprising stacking unit cells. 2. A method for manufacturing a flat solid electrolyte fuel cell comprising a separator, an air electrode, a solid electrolyte and a fuel electrode, wherein a separator is deposited on a smooth surface of the air electrode and a thin film is integrally formed. Integrated part A
-2 and an integrated part B formed by depositing a solid electrolyte on the smooth surface of the fuel electrode to form a single thin film integrally
Wherein the air electrode and the fuel electrode are directly opposed to each other and sandwich the solid electrolyte membrane so as to form a unit cell, and the unit cells are stacked to form a flat solid electrolyte fuel. Battery manufacturing method. 3. The integrated portion A-3 is formed by further forming and firing a thin film made of the same material as the fuel electrode on the surface of the solid electrolyte thin film of the integrated portion A-1. 2. The production method according to 1. 4. An integrated portion A-4 is formed by further forming and firing a thin film made of the same material as the air electrode on the surface of the solid electrolyte thin film of the integrated portion B-2. 2. The production method according to 2.