JPH08273683A - Manufacture of fuel cell - Google Patents

Abstract

PURPOSE: To provide a manufacturing method of high temperature solid electrolyte fuel cell by which large output is obtained. CONSTITUTION: After gelatinizing and drying a solution composition composed of a zirconium alkoxide, a hydrate of an yttrium nitrate and first and second solvents, it is pulverized. After obtained powder is temporarily baked at 100 to 700 deg.C, it is pulverized, and yttria-containing zirconia powder is obtained. A paint film is formed on a porous electrode 1 or 4 by a paint film forming composition containing the powder, and it is baked, and a backing layer 2 composed of yttria stabilizing zirconia is formed. A paint film is formed on the backing layer 2 by the solution composition, and it is dried and baked, and a dense solid electrolyte film 3 composed of yttria stabilizing zirconia is formed. The backing layer 2 is formed by spraying of a suspension by dispersing YZ powder in an alcohol type solvent or dripping, soaking and electrodeposition of a suspension by dispersing the suspension or the YZ powder in sol of the solution composition. It is also formed by application of a paste-like substance by dispersing YZ powder in turpentine oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a high temperature solid oxide fuel cell.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, for example, a high temperature solid electrolyte fuel is air composed of a metal oxide (lanthanum strontium manganite) having a porous LaMnO ₃ type crystal structure (perovskite type structure). A dense solid electrolyte membrane 3 is formed on the electrode 1, and a fuel electrode 4 made of a porous Ni-yttria-stabilized zirconium cermet or the like is further formed thereon.

The solid electrolyte membrane 3 is preferably a thin and dense membrane made of cubic zirconia in order to obtain high electric conductivity, but such a dense solid electrolyte membrane 3 is formed by plasma spraying or electrochemical deposition. It can be manufactured only by the (EVD) method. In order to manufacture by the above-mentioned method, an expensive device is required, and it takes a long time to mask the part that needs the solid electrolyte membrane 3 and the part that does not need the solid electrolyte membrane 3. Therefore, mass productivity is low. Become.

Therefore, it has been considered to apply a slurry of zirconia powder containing a stabilizer such as yttria to the air electrode 1 or the fuel electrode 4 and then to bake it, but the zirconia powder shrinks during firing. However, there is a problem that the solid electrolyte membrane formed from the slurry is cracked or peeled off from the air electrode.

In order to solve the problem of shrinkage during firing of the zirconia powder, the present inventors have already dissolved a zirconium alkoxide such as zirconium propoxide and yttrium nitrate hydrate in a solvent common to both 1-propanol and the like. In addition, a coating solution composition in which a solvent that dissolves both of 2,4-pentanedione and the like is added is proposed (see Japanese Patent Application No. 6-272704). According to the coating solution composition described in the above specification, a dense solid electrolyte membrane of cubic zirconia stabilized with yttria is obtained by gelling a sol generated in a solution and heating and firing the gel. To be

Accordingly, the coating solution composition comprises
The dense solid electrolyte membrane 3 can be formed as described above by coating the air electrode 1 or the fuel electrode 4, gelling it, and then firing it. However, an output that is practical as a fuel cell can be obtained. Further improvements are desired to obtain.

[0007]

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a method for manufacturing a high temperature solid oxide fuel cell which can provide a large output.

[0008]

In order to achieve the above object, a method for producing a fuel cell according to the present invention comprises a zirconium alkoxide, a yttrium nitrate hydrate, and a first solvent which dissolves both of the compounds in a homogeneous manner. And a gel obtained from a solution composition consisting of both of the compounds and a second solvent that dissolves the reaction product thereof homogeneously after drying, and then pulverized into a powder, the powder having a temperature in the range of 100 to 700 ° C. After being calcined in, a coating film-forming composition containing yttria-containing zirconia powder (hereinafter abbreviated as YZ powder) obtained by further pulverization was used to form a coating film on the porous electrode of the high temperature solid oxide fuel cell Forming a base layer by baking the coating film to form a base layer made of yttria-stabilized zirconia (hereinafter abbreviated as YSZ); and forming a coating film on the base layer by the solution composition. And, the coating film was dried and baked, Y
And a solid electrolyte membrane forming step of forming a dense solid electrolyte membrane made of SZ.

Examples of the zirconium alkoxide used in the solution composition as the raw material of the YZ powder include zirconium propoxide, zirconium isopropoxide, zirconium butoxide, etc., but a dense solid electrolyte membrane can be obtained. Zirconium propoxide is suitable because of its solubility in the first solvent common to yttrium nitrate.

Examples of the first solvent include 1-propanol, 2-propanol, 2-methyl-1-propanol, benzene, hexane, methanol, ethanol and the like. The zirconium alkoxide and yttrium nitrate hydrate are mentioned. 1-Propanol is suitable because it has excellent solubility in both substances.

Examples of the second solvent include 2,4-pentanedione (acetylacetone), triethanolamine and diethanolamine, and the zirconium alkoxide, yttrium nitrate hydrate and the reaction product thereof are homogeneous. 2,4-Pentanedione is suitable because it is highly soluble.

When the coating film forming composition is a suspension prepared by dispersing the YZ powder in an alcohol solvent, the coating film forming composition is sprayed onto the porous electrode in the base layer forming step. The coating film is formed by applying and drying. Alternatively, a method of dropping the coating film forming composition on the porous electrode and drying, a method of immersing the porous electrode in the coating film forming composition and drying, the porous electrode and other electrodes Is immersed in the coating film-forming composition, a direct current is applied between the other electrode and the porous electrode as a cathode, and the yttria-containing zirconia powder is electrodeposited on the porous electrode and dried. The coating film is formed by the method described above.

Further, when the coating film forming composition is a suspension obtained by dispersing the YZ powder in a sol obtained from the solution composition as a raw material thereof, the coating film forming step is performed in the base layer forming step. A method of dropping a forming composition on the porous electrode and drying, a method of immersing the porous electrode in the coating film forming composition and drying, a method of forming the porous electrode and another electrode to form the coating film. The composition is dipped in a composition, a direct current is applied between the other electrode and the porous electrode as a cathode, the yttria-containing zirconia powder is electrodeposited on the porous electrode, and the coating is performed by a method of drying. Form a film.

Further, when the coating film forming composition is a paste-like substance formed by mixing the YZ powder with turpentine oil, the paste-like substance is applied onto the porous electrode in the base layer forming step. Then, the coating film is formed by drying.

[0015]

According to the method for producing a fuel cell of the present invention, first,
Zirconium alkoxide such as zirconium propoxide, yttrium nitrate hydrate, a first solvent such as 1-propanol that dissolves both compounds homogeneously, and both compounds and reaction products thereof dissolve homogeneously. A solution composition is prepared by mixing a second solvent such as 2,4-pentanedione. In this solution composition, zirconium alkoxide and yttrium nitrate hydrate react with each other in the solution to form a sol, and the sol gels as the reaction progresses.

Then, after drying the gel, it is pulverized into a powder, the powder is calcined at a temperature in the range of 100 to 700 ° C., and then further pulverized to obtain a zirconia powder containing yttria composed of fine particles. (YZ powder) is obtained. If the calcination temperature is lower than 100 ° C, decomposition of organic components such as a solvent is insufficient, and if it exceeds 700 ° C, the particles of the obtained powder tend to be large.

Next, a coating film forming composition containing the YZ powder is prepared. The coating film composition is prepared by dispersing the YZ powder in a solvent or the like, and the solvent may be water, an inorganic solvent, an organic solvent or the like as long as it can disperse the YZ powder. Good. However, since the YZ powder composed of the fine particles is unlikely to settle when dispersed, and has excellent volatility when the coating composition is applied, an alcohol solvent is preferably used, and particularly preferable. Is ethanol. Further, the coating composition may be a suspension in which the YZ powder is dispersed in a sol obtained from the solution composition as a raw material thereof to form a suspension.
The powder may be mixed with turpentine oil to form a pasty substance.

Next, when the coating composition is applied onto the porous electrode of the high temperature solid oxide fuel cell, the YZ powder consisting of the fine particles penetrates into the fine pores formed on the surface of the porous electrode. Then, a coating film in which the fine holes are buried is formed.
Then, when the coating film is baked, the YZ powder contained in the coating film composition is composed of the fine particles as described above, and thus forms an extremely dense film. Moreover, the YZ powder is
The firing results in YSZ.

Therefore, the solid electrolyte membrane having a desired thickness may be formed only by the film formed from the coating composition, but the YZ powder contained in the coating composition is as described above. Since it consists of fine particles, the coating composition has to be applied more than once in order to obtain the required solid electrolyte membrane, which complicates the operation.

Therefore, in the production method of the present invention, a film formed from the coating film composition is used as an underlayer, and the solution composition which is a raw material of the YZ powder is applied onto the underlayer and gelled. By firing the gel, a required solid electrolyte membrane is formed.

In the step of forming the undercoat layer, when the coating composition is a suspension prepared by dispersing the YZ powder in ethanol, ethanol is a solvent excellent in volatility and fluidity, and thus sprayed. The coating film composition is formed by spraying the coating film composition onto the porous electrode with a gun or the like, or dropping and drying the composition. Alternatively, a method of immersing the porous electrode in the coating film forming composition and drying it, immersing the porous electrode and other electrodes in the coating film forming composition, and using the porous electrode as a cathode A direct current is applied between the electrode and the electrode to deposit the yttria-containing zirconia powder on the porous electrode, and the coating is formed by a method of drying.

When the coating composition is a suspension prepared by dispersing the YZ powder in a sol obtained from the solution composition as a raw material, the suspension uses ethanol as a solvent. Since the viscosity is higher than that of a suspension and the amount attached to the porous electrode is large, a method of immersing the porous electrode in the coating film forming composition and drying, or the porous electrode and other An electrode is immersed in the coating film forming composition, a direct current is applied between the other electrode and the porous electrode as a cathode, and the yttria-containing zirconia powder is electrodeposited on the porous electrode, The coating film is formed by a drying method. Alternatively, the coating film is formed by dropping the coating film composition on the porous electrode and drying.

When the coating composition is a paste-like substance formed by mixing the YZ powder with turpentine oil, the paste-like substance has an extremely high viscosity, so that the porous electrode of the coating composition is Since it adheres to the porous electrode easily, the paste-like substance is directly applied onto the porous electrode by a brush or the like and dried to form the coating film.

[0024]

EXAMPLE 1 Next, the method for producing a fuel cell of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is an explanatory cross-sectional view showing one structural example of the fuel cell of this example, and FIG. 2 is a YZ used for the coating film forming composition of this example.
4 is a graph showing the relationship between the particle size distribution of the powder and the calcination temperature, FIG. 3 is a graph showing the results of thermal analysis of the YZ powder used in the coating film forming composition of this example, and FIG. 4 is shown in FIG. 5 is a graph showing the result of X-ray diffraction of the underlayer of FIG. 5, and FIG. 5 is an explanatory cross-sectional view showing another configuration example of the fuel cell of this example.

As shown in FIG. 1, the fuel cell manufactured in this example has a base layer 2 made of YSZ and a solid body made of YSZ on the outer side of an air electrode 1 formed in a cylindrical shape having a hemispherical bottom. The electrolyte membrane 3 is provided, and the fuel electrode 4 is provided further outside the solid electrolyte membrane 3.

Next, a method of manufacturing the fuel cell shown in FIG. 1 will be described.

First, lanthanum oxide, manganese dioxide, and strontium carbonate are added at a La: Sr: Mn molar ratio of 0.
Mix and mold so that it becomes 7: 0.3: 1 and 110
After calcination at 0 ° C., it was pulverized to obtain a powder. Next, 30% by weight of corn starch was added to and mixed with the obtained powder, and the mixture was molded into an electrode shape shown in FIG.
After degreasing by heating from room temperature to 600 ° C, it is further baked at 1300 ° C to obtain La with an apparent porosity of about 40%.
A porous air electrode 1 was produced as a metal oxide (lanthanum strontium manganite) substrate having a MnO ₃ system crystal structure. In the preparation of the air electrode, the corn starch is used to make the substrate obtained by firing porous.

Next, YS is applied to the outside of the porous air electrode 1.
A base layer 2 made of Z was formed.

In this example, in order to form the underlayer 2, a coating film forming composition prepared as follows was used. The coating film forming composition of this example was prepared by first adding a 1.5 M-1-propanol solution of zirconium propoxide,
1.5 of 2,4-pentanedione (acetylacetone)
The M-1-propanol solution was added and mixed such that zirconium was contained in a ratio of 2 (molar ratio) to 2,4-pentanedione, and then mixed with yttrium nitrate 5
A 0.261M-1-propanol solution of the hydrate was mixed with the zirconium propoxide solution in an equal amount and stirred to prepare a solution composition. In the solution composition, 1-propanol is used as a common solvent for zirconium propoxide and yttrium nitrate hydrate, and 2,4-pentanedione is used as a homogenizing solvent for homogenizing the solution. Composition of zirconia: yttria = 9
The ratio is 2: 8 (molar ratio).

When the solution composition is continuously stirred, the zirconium alkoxide is hydrolyzed and polymerized in the solution by mixing the crystal water of yttrium nitrate or water vapor in the air to polymerize the zirconium alkoxide. Alternatively, a sol in which hydroxide particles or ions are dissolved is formed. When the sol is further stirred, the reaction proceeds and gels.

Then, next, the gel obtained from the solution composition was dried at about 100 ° C., and the obtained solid substance was pulverized in a mortar into powder. The powder is then added to 100-70
The yttria-containing zirconia powder (YZ powder) was obtained by calcination at a temperature in the range of 0 ° C. and crushing in a mortar.

The coating film forming composition used in this example is shown in FIG.
In order to bury the fine pores on the surface of the air electrode 1 shown in the figure to form the underlayer 2, it is desirable that the particle size is small. As shown in FIG.
Although YZ powder having a small center particle size can be obtained by calcining at, the center particle size tends to increase when the temperature exceeds 700 ° C.

Further, as is clear from the results of thermogravimetric measurement (TG) in the thermal analysis shown in FIG. 3, the YZ powder had its weight rapidly decreased up to 400 ° C., and when the temperature exceeded 400 ° C. It is decreasing gradually. From the result of the differential thermal analysis (DTA) of the thermal analysis shown in FIG.
There is an exothermic peak that is considered to be due to thermal decomposition of an organic component such as a solvent, and a broad peak that is considered to be due to crystallization of yttria and zirconia near 300 to 350 ° C. Therefore, the YZ powder does not reach YSZ,
It is considered to be a mixture containing organic components such as a solvent.

Next, 3 to 4 g of the YZ powder was put into 100 ml of ethanol, and the container was placed in an ultrasonic cleaner to irradiate ultrasonic waves for about 3 minutes to disperse the ultrasonic waves, and then a magnetic stirrer was used. Stir for about 10 minutes. After stirring, the mixture was allowed to stand for about 10 minutes to settle large particles, whereby a supernatant liquid in which the fine particles of the YZ powder were suspended in ethanol was obtained as the first coating film-forming composition.

In the manufacturing method of the present embodiment, next, the air electrode 1 is heated to about 100 ° C. with a hot plate, and the first coating film forming composition is dropped on the outer surface thereof with a dropper. Then, after drying several times, 100
By firing at 0 to 1300 ° C for 1 hour, the thickness is about 3
A base layer 2 having a thickness of μm was formed.

Next, a solid electrolyte membrane 3 made of YSZ was formed on the outside of the underlayer 2. To form the solid electrolyte membrane 3, first, the air electrode 1 on which the underlayer 2 is formed is dipped in the coating solution composition by using the sol of the solution composition of the raw material of the YZ powder as the coating solution composition, The coating solution was attached to the surface and gelled. In the immersion, an appropriate amount of the coating solution is attached by setting the pulling rate when pulling up the air electrode 1 from the coating solution composition to be 0.05 mm / sec or more.
The dipping is performed in order to obtain the desired solid electrolyte membrane 3.
It is preferably performed about 30 times, and particularly preferably about 20 times in order to obtain the solid electrolyte membrane 3 having a thickness of about 3 μm.

Next, the air electrode 1 having the coating solution gelled on its surface is heated from room temperature to 500 ° C. at a temperature rising rate of 1.6 ° C./sec or less and calcined for 10 minutes, and then 1
The dense solid electrolyte membrane 3 made of YSZ was formed by heating to 000 to 1300 ° C., firing for 5 hours, and cooling. By repeating the operation of forming the solid electrolyte membrane 3 several more times, the final thickness is about 10 μm.
The air electrode 1 provided with the solid electrolyte membrane 3 was obtained.

Next, the fuel electrode 4 was formed further outside the solid electrolyte membrane 3 to complete the fuel cell. Fuel electrode 4
First, a nickel powder having a central particle size of 1 μm and a central particle size of 2 μm
YSZ powder having a molar ratio of yttria of m to zirconia of 8:92 was mixed in a weight ratio of 4: 6, and 30% by weight of corn starch was added to the resulting mixture, The mixed material was applied to the outside of the solid electrolyte membrane 3 to form an electrode shape, and baked at 1400 ° C. for 2 hours to obtain a NiO-YSZ substrate having an apparent porosity of about 35.3%. Next, the NiO-YSZ substrate was fired at 1000 ° C. for 1 hour in the coexistence of carbon to reduce NiO to form a porous Ni-YSZ cermet substrate, which was used as a fuel electrode 4. The fuel electrode 4 may be a platinum paste electrode.

The arrangement of the air electrode 1 and the fuel electrode 4 may be reversed. At this time, the firing temperature is 1200 to outside the fuel electrode 4 which is formed in a cylindrical shape having a hemispherical bottom.
A fuel cell is obtained by forming a base layer 2 made of YSZ and a solid electrolyte membrane 3 made of YSZ and forming an air electrode 1 further outside the solid electrolyte membrane 3 in the same manner as above except that the temperature is set to 1400 ° C. .

The fuel cell having the underlayer 2 and the solid electrolyte membrane 3 formed as described above has a temperature of 800 ° C. or higher of 0.3.
An output of W / cm ² or more was obtained.

[0041]

Example 2 In this example, the air electrode 1 or the fuel electrode 4 shown in FIG. 1 was dipped in the first coating film-forming composition obtained in Example 1 to form the coating film on the outer surface thereof. Deposit the composition,
After repeating the operation of drying at room temperature, calcining at 500 ° C. for 10 minutes and cooling several times, and then calcining at a predetermined calcining temperature for 1 hour, the underlayer 2 having a thickness of about 3 μm was formed. A fuel cell including a solid electrolyte membrane 3 having a thickness of about 10 μm was obtained in the same manner as in Example 1. The firing temperature is 1000 to 1,000 when the underlayer 2 is formed on the surface of the air electrode 1.
The temperature is 1300 ° C, and the temperature is 1200 to 1400 ° C when the underlayer 2 is formed on the surface of the fuel electrode 4. As described above, the fuel cell on which the underlayer 2 and the solid electrolyte membrane 3 were formed could obtain an output of 0.3 W / cm ² or more at 800 ° C. or more.

[0042]

Example 3 In this example, the first coating film-forming composition obtained in Example 1 was heated to about 100 ° C. on a hot plate to the outside of the air electrode 1 or the fuel electrode 4 shown in FIG. The surface is sprayed with a spray gun for painting, dried, and baked at a specified baking temperature for 1 hour to give a thickness of approximately 3 μm.
A fuel cell including a solid electrolyte membrane 3 having a thickness of about 10 μm was obtained in the same manner as in Example 1 except that the underlayer 2 was formed. The fuel cell on which the underlayer 2 and the solid electrolyte membrane 3 are formed as described above is 0.3 W / cm at 800 ° C. or higher.
More than ² outputs were obtained.

[0043]

Example 4 In this example, an electrode formed by winding a nickel wire into a coil was immersed in a container containing the first coating film-forming composition obtained in Example 1, and the inside of the coiled electrode was immersed. To Figure 1
A nickel wire wound in a coil around the air electrode 1 or the fuel electrode 4 shown in the figure is immersed, and the coiled electrode is used as an anode, and the air electrode 1 or the fuel electrode 4 is used as a cathode.
A constant DC current of 30 mA at 30 mA is applied for 5 to 10 minutes to electrodeposit YZ powder particles on the outer surface of the air electrode 1 or the fuel electrode 4, and after drying, calcination is performed at a predetermined calcination temperature for 1 hour. Except that the underlayer 2 having a thickness of about 3 μm is formed by
A solid electrolyte membrane 3 having a thickness of about 10 μm as in Example 1
A fuel cell having Underlayer 2 as described above
And the fuel cell on which the solid electrolyte membrane 3 is formed is 800 ° C.
With the above, an output of 0.3 W / cm ² or more was obtained.

[0044]

[Embodiment 5] In this embodiment, 3 to 4 g of the YZ powder obtained in Embodiment 1 is used as a sol 1 of a solution composition as a raw material of the YZ powder.
The mixture was put into an amount of 00 ml, and the whole container was placed in an ultrasonic cleaner to radiate ultrasonic waves for about 3 minutes to disperse the ultrasonic waves, and then stirred with a magnetic stirrer for about 10 minutes. After stirring, the mixture was allowed to stand for about 10 minutes to settle large particles, whereby a supernatant liquid in which fine particles of the YZ powder were suspended in the sol was obtained as a second coating film forming composition.
The concentration of zirconium poropoxide in the sol was 0.
It is preferably 6 M or less, and when it is more than 6 M, cracks are likely to occur in the underlayer 2 obtained from the second coating film forming composition.

In this example, the air electrode 1 or the fuel electrode 4 shown in FIG. 1 was heated to about 100 ° C. on a hot plate, and the second coating film forming composition was dropped on it by a dropper, The drying operation was repeated several times, and then the base layer 2 having a thickness of about 3 μm was formed by firing at a predetermined firing temperature for 1 hour.
A fuel cell provided with a solid electrolyte membrane 3 of μm was obtained. As described above, the fuel cell on which the underlayer 2 and the solid electrolyte membrane 3 were formed could obtain an output of 0.3 W / cm ² or more at 800 ° C. or more.

As a result of the X-ray diffraction measurement of the underlayer 2 obtained in this example, the pattern shown in FIG. 4 was obtained. The pattern had a molar ratio of yttria to zirconia of 8:
This is in agreement with YSZ of 92, and it is clear that the YZ powder obtained in Example 1 is crystallized by the above firing to form YSZ.

[0047]

Example 6 In this example, the air electrode 1 or the fuel electrode 4 shown in FIG. 1 was immersed in the second coating film-forming composition obtained in Example 5, and the coating film was formed on the outer surface thereof. Deposit the composition,
After repeating the operation of drying at room temperature, calcining at 500 ° C. for 10 minutes and cooling several times, and then calcining at a predetermined calcining temperature for 1 hour, the underlayer 2 having a thickness of about 3 μm was formed. A fuel cell including a solid electrolyte membrane 3 having a thickness of about 10 μm was obtained in the same manner as in Example 1. The fuel cell in which the underlayer 2 and the solid electrolyte membrane 3 are formed as described above is 800
An output of 0.3 W / cm ² or more was obtained at a temperature of ° C or higher.

[0048]

Example 7 In this example, an electrode formed by winding a nickel wire into a coil was immersed in a container containing the second coating film-forming composition obtained in Example 5, and the inside of the coiled electrode was immersed. To Figure 1
A nickel wire wound in a coil around the air electrode 1 or the fuel electrode 4 shown in the figure is immersed, and the coiled electrode is used as an anode, and the air electrode 1 or the fuel electrode 4 is used as a cathode.
By passing a constant DC current of mA, 30 V for 5 to 10 minutes to electrodeposit YZ powder particles on the surface of the air electrode 1 or the fuel electrode 2, and after drying, firing at a predetermined firing temperature for 1 hour, A fuel cell including a solid electrolyte membrane 3 having a thickness of about 10 μm was obtained in the same manner as in Example 1 except that the underlayer 2 having a thickness of about 3 μm was formed. The fuel cell having the underlayer 2 and the solid electrolyte membrane 3 formed as described above provided an output of 0.3 W / cm ² or more at 800 ° C. or higher.

[0049]

Example 8 In this example, 24 g of the YZ powder obtained in Example 1 was added to 2 to 5 ml of turpentine oil and stirred well to form a paste, whereby the third coating film-forming composition was obtained. Obtained.

In this example, the third coating film-forming composition was applied to the air electrode 1 or the fuel electrode 4 shown in FIG.
After repeating the operation of drying with hot air several times, 1200 to
By firing at 1400 ℃ for 1 hour, the thickness is about 5μm
A fuel cell including a solid electrolyte membrane 3 having a thickness of about 10 μm was obtained in the same manner as in Example 1 except that the underlayer 2 was formed. A fuel cell having the underlayer 2 and the solid electrolyte membrane 3 formed as described above has a temperature of 800 ° C. or higher of 0.3 W / cm ²
The above output was obtained.

In each of the examples, the firing temperature for forming the underlayer 2 is 1000 to 1300 ° C. when the underlayer 2 is formed on the surface of the air electrode 1, and the fuel electrode 4 is used.
1200 to 140 when the underlayer 2 is formed on the surface of
0 ° C.

[0052]

[Embodiment 9] In each of the above embodiments, an example of a cylindrical battery having a hemispherical bottom as shown in FIG. 1 has been described. However, the manufacturing method of the present invention is the coin type battery shown in FIG. Can also be applied.

Next, a method of manufacturing the coin battery shown in FIG. 5 will be described. First, using a material similar to that used in Example 1, as shown in FIG.
m to a disk shape with a thickness of about 2 to 3 mm, from room temperature to 6
After degreasing by heating at a temperature of 00 ° C, further 1300
A porous air electrode 1 similar to that of Example 1 is manufactured by firing at 0 ° C., and then any of the above-mentioned examples is formed outside the porous air electrode 1 as shown in FIG. 5B. By the method YSZ
The underlayer 2 having a thickness of about 3 μm is formed.

Next, as shown in FIG. 5C, a solid electrolyte membrane 3 having a thickness of about 10 μm was formed on the underlayer 2 in the same manner as in Example 1, and the lower surface of the obtained disk-shaped body was formed. Figure 5
The portion shown in phantom in (c) is ground to expose the air electrode 1 as shown in FIG. 5 (d). The polishing can be performed by a method known per se.

Next, as shown in FIG. 5E, the apparent porosity was about 35.3 on the disk-shaped solid electrolyte membrane 3 with the air electrode 1 exposed on the lower surface side in the same manner as in Example 1. % NiO-
The YSZ substrate 4a is baked. NiO-YSZ substrate 4a
NiO is reduced by firing at 1000 ° C. for 1 hour in the presence of carbon, and the fuel electrode 4 of the porous Ni—YSZ cermet substrate is obtained as shown in FIG.
As in the first embodiment, the air electrode 1 and the fuel electrode 4 may be arranged in reverse.

In the coin-type fuel cell having the underlayer 2 and the solid electrolyte membrane 3 formed as described above, an output of 0.3 W / cm ² or more can be obtained at 800 ° C. or higher as in the above-mentioned respective examples. To be

[0057]

As is apparent from the above, according to the production method of the present invention, a coating film forming composition containing YZ powder consisting of fine particles on the porous electrode of a high temperature solid oxide fuel cell. Since the underlayer is formed by, the micropores on the surface of the porous electrode are buried by the underlayer, and the solid electrolyte membrane is formed on the underlayer with the solution composition as the raw material of the YZ powder. A thin and dense solid electrolyte membrane made of YSZ can be easily formed. Moreover, since the base layer itself becomes YSZ by firing, the solid electrolyte membrane can be integrated with the base layer and can be surely adhered to the porous electrode.

Therefore, according to the manufacturing method of the present invention, by forming the thin and dense solid electrolyte membrane as described above, a high output fuel cell can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view showing one structural example of a high temperature solid oxide fuel cell according to the present invention.

FIG. 2 is a graph showing the relationship between the particle size distribution of YZ powder used in the coating film forming composition of this example and the calcination temperature.

FIG. 3 is a graph showing the results of thermal analysis of YZ powder used in the coating film forming composition of this example.

FIG. 4 is a graph showing the results of X-ray diffraction of the underlayer shown in FIG.

FIG. 5 is an explanatory cross-sectional view showing another configuration example of the high temperature solid oxide fuel cell according to the present invention.

FIG. 6 is an explanatory cross-sectional view showing the structure of a conventional high temperature solid oxide fuel cell.

[Explanation of symbols]

1, 4 ... Porous electrode, 2 ... Underlayer, 3 ... Solid electrolyte membrane.

Claims (11)

[Claims] 1. A zirconium alkoxide, yttrium nitrate hydrate, a first solvent that dissolves both compounds in a homogeneous manner, and a second solvent that dissolves both compounds and their reaction products in a homogeneous manner. After drying the gel obtained from the solution composition, it is pulverized into a powder, and the powder is 100-700.
After calcination at a temperature in the range of ° C, a coating film-forming composition containing the yttria-containing zirconia powder obtained by further pulverization forms a coating film on the porous electrode of the high temperature solid oxide fuel cell, A base layer forming step of forming a base layer made of yttria-stabilized zirconia by baking the coating film, and the solution composition, to form a coating film on the base layer,
A solid electrolyte membrane forming step of forming a dense solid electrolyte membrane of yttria-stabilized zirconia by drying and firing the coating film. 2. The method for producing a fuel cell according to claim 1, wherein the zirconium alkoxide is zirconium propoxide. 3. The method for producing a fuel cell according to claim 1, wherein the first solvent is 1-propanol. 4. The method for producing a fuel cell according to claim 1, wherein the second solvent is 2,4-pentanedione. 5. The coating film forming composition is a suspension obtained by dispersing the yttria-containing zirconia powder in an alcoholic solvent, according to any one of claims 1 to 4. Of manufacturing a fuel cell of. 6. The fuel cell according to claim 5, wherein in the step of forming the underlayer, the coating film is formed by spraying the coating film forming composition onto the porous electrode and drying. Manufacturing method. 7. The coating film forming composition is a suspension obtained by dispersing the yttria-containing zirconia powder in a sol obtained from the solution composition. The method for manufacturing a fuel cell according to any one of claims 1. 8. The coating film is formed by dropping the coating film forming composition on the porous electrode in the step of forming the underlayer and drying the composition. 7. The method for producing a fuel cell according to 7. 9. The coating film is formed by immersing the porous electrode in the coating film forming composition and drying in the base layer forming step. Of manufacturing a fuel cell of. 10. In the step of forming the underlayer, the porous electrode and another electrode are immersed in the coating film forming composition, and a direct current is applied between the porous electrode and the other electrode as a cathode. The method for producing a fuel cell according to claim 5 or 7, wherein the yttria-containing zirconia powder is electrodeposited on the porous electrode and dried to form the coating film. 11. The coating film forming composition is a paste-like substance formed by mixing the yttria-containing zirconia powder with turpentine oil, and the paste-like substance is formed on the porous electrode in the underlayer forming step. The method for producing a fuel cell according to claim 1, wherein the coating film is formed by applying and drying.