JPH04218264A - Manufacturing method of solid electrolyte fuel cell - Google Patents

Abstract

PURPOSE:To control contraction in the case of baking a complex compact and porosity of a fuel electrode by constituting a complex compact having a fuel electrode compact on an electrolyte compact by means of metallic oxide or slurry formed by adding metal and carbonic powder together. CONSTITUTION:After an electrolyte compact 5 is formed by using slurry containing zirconia obtained by adding a stabilizing agent therein, metallic oxide or slurry containing metal and carbonic powder is poured onto the electrolyte compact 5 so as to constitute a fuel electrode compact 6 as a complex compact, and then by baking it, a solid electrolyte - fuel electrode complex having a fuel electrode 7 on one surface and a solid electrolyte film 8 on the other surface is formed. Since the solid electrolyte film 8 and the fuel electrode 7 can integrally be constituted in one body, its porosity and mechanical strength can be controlled optionally, so that a solid electrolyte fuel cell having high performance can be realized.

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 solid electrolyte fuel cells.

0002

[Prior Art] Solid electrolyte fuel cells include a phosphoric acid fuel cell, a flat plate type with a structure similar to a molten carbonate fuel cell, a monolithic type proposed by Argonne National Laboratory in the United States, and a Japanese electronics technology complex. The cylindrical multi-element type currently being developed by the Institute, and the cylindrical single element type proposed by Westinghouse Corporation in the United States, are well known, but currently Westing is currently developing a cylindrical multi-element type that is being developed by Westinghouse, Inc. in the United States. Guhaus' cylindrical single element type is attracting attention.

Methods for manufacturing the solid electrolyte used in such solid electrolyte fuel cells include plasma spraying, chemical vapor deposition (CVD), electrochemical vapor deposition (EVD), and thermal decomposition of organometallic zirconium salts. Although it is known,
The only methods for obtaining a dense solid electrolyte membrane are plasma spraying and electrochemical vapor deposition (EVD).

Furthermore, as a method for producing a dense solid electrolyte membrane as described above, an attempt has been made to make a slurry of stabilized zirconia powder 3, apply it onto a base material 1, and sinter it as shown in FIG. .

[0005]

[Problem to be Solved by the Invention] The former manufacturing method described above requires expensive manufacturing equipment and takes time to mask the parts that require a solid electrolyte membrane and the parts that do not. Therefore, there was a problem with the mass production of batteries.

Furthermore, in the latter manufacturing method, since the stabilized zirconia powder 3 shrinks during firing, cracks 2 may occur in the solid electrolyte membrane 8 formed on the base material 1 or the solid electrolyte membrane 8 may peel off. There was a problem.

[0007]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a step of forming an electrolyte molded body by molding a slurry containing zirconia to which a stabilizer has been added, and a step of forming one of the electrolyte molded bodies. A step of forming a slurry containing metal or metal oxide and carbon powder on a surface to form a fuel electrode compact, and obtaining a composite compact in which the electrolyte compact and the fuel electrode compact are integrated; A step of firing a composite molded body to obtain a solid electrolyte-fuel electrode composite, and
This is characterized in that an air electrode is formed on the solid electrolyte side of the fuel electrode composite.

[0008]

[Operation] As described above, the present invention provides a solid electrolyte-fuel electrode by firing a composite molded body in which an electrolyte molded body and a fuel electrode molded body are integrated using carbon powder contained in the fuel electrode molded body. When forming a composite, the carbon powder is oxidized and released to the outside as carbon monoxide or carbon dioxide. Therefore, by controlling the amount of carbon powder contained, the shrinkage on the fuel electrode side can be reduced to the shrinkage on the solid electrolyte membrane side. It can be approximated.

Furthermore, by controlling the particle size of the carbon powder, the porosity on the fuel electrode side can be changed.

Furthermore, in the present invention, since the composite molded body is fired, the strength of the fuel electrode is increased and it also functions as a base material.

[0011]

[Example] Fig. 1 is a cross-sectional view of an electrolyte molded body 5 formed by the method for producing a solid electrolyte fuel cell of the present invention. zirconia, water, dispersion material,
The state is shown in which a slurry consisting of a binder and an antifoaming agent is poured in, left to stand for a certain period of time, and then the excess slurry is removed.

FIG. 2 shows one side of the electrolyte molded body 5,
That is, this is a cross-sectional view of a state in which the fuel electrode molded body 6 is formed on the inner surface, and after pouring a slurry containing metal or metal oxide and carbon powder onto the inner surface of the electrolyte molded body 5 and leaving it for a certain period of time, The figure shows a state in which the excess slurry has been removed to form a composite molded body in which the electrolyte molded body 5 and the fuel electrode molded body 6 are integrated.

FIG. 3 is a cross-sectional view of a solid electrolyte-fuel electrode composite obtained by drying the composite molded body of FIG. 2, removing the mold 4, and then firing it. A dense solid electrolyte membrane 8 is formed on the outside.

[0014] When firing the composite molded body, the fuel electrode molded body 6
Since the carbon powder contained therein is oxidized and released to the outside as carbon monoxide or carbon dioxide, increasing the amount of carbon powder contained increases the shrinkage rate on the fuel electrode 7 side. On the other hand, since the shrinkage rate on the solid electrolyte membrane 8 side is almost constant, the amount of carbon powder contained in the fuel electrode molded body 6 is controlled, and the shrinkage rate on the fuel electrode 7 side is adjusted to the solid electrolyte membrane 8 side. By approximating the shrinkage rate to , it is possible to simultaneously manufacture the porous fuel electrode 7 and the dense solid electrolyte membrane 8.

On the other hand, depending on the amount of yttria added, zirconia can be made into cubic zirconia, tetragonal zirconia, or partially stabilized zirconia, and the strength of the solid electrolyte membrane 8 can be controlled. By using it together with controlling the amount of powder, cracking and peeling of the composite molded body during firing can be prevented, and the performance of the solid electrolyte-fuel electrode composite can be improved.

FIG. 4 is a cross-sectional view of a state in which strontium-doped LaMnO3 is formed as an air electrode 9 on the outside of the solid electrolyte membrane 8 of the solid electrolyte-fuel electrode composite by the dipping method, that is, by the manufacturing method of the present invention. FIG. 3 is a cross-sectional view of the obtained solid electrolyte fuel cell. Note that methods for forming the air electrode 9 include, in addition to the dipping method, a slurry coating method, a thermal spraying method, and the like, and it goes without saying that the method is not particularly limited.

When the solid electrolyte fuel cell thus obtained as shown in FIG. 4 is heated from the operating temperature of 700° C. to 1000° C., and fuel is supplied to the fuel electrode 7 side and air to the air electrode 9 side, the fuel The nickel oxide in the fuel electrode 7 is reduced by this.

Therefore, when the fuel electrode 7 and the air electrode 9 in FIG. 4 are connected to an external circuit, the oxygen taken in from the air electrode 9 takes in the electrons supplied from the external circuit and becomes oxygen ions. It passes through the solid electrolyte membrane 8 and reaches the interface between the solid electrolyte membrane 8 and the fuel electrode 7 .

On the other hand, hydrogen or carbon monoxide that has diffused through the fuel electrode 7 is present at this interface, and this hydrogen or carbon monoxide reacts with the oxygen ions to generate water vapor and carbon dioxide. Since electrons are emitted to the external circuit, an electromotive force is generated in the external circuit with the air electrode 9 as the positive electrode and the fuel electrode 7 as the negative electrode, and it functions as a battery.

In the above explanation, a composite molded body is formed using the mold 4, but it goes without saying that a flat plate-shaped composite molded body can be formed by molding the slurry into a tape shape using a calendar roll or the like.

[0021]

[Effects of the Invention] As described above, according to the present invention, a dense solid electrolyte membrane 8 and a porous fuel electrode 7 can be easily formed, and the porosity can be changed by controlling the particle size of the carbon powder contained therein. Since the mechanical strength can be changed by controlling the amount of carbon powder contained, a high-performance solid electrolyte fuel cell can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a state in which surplus slurry is removed after slurry is poured into a mold 4 and left for a certain period of time to form an electrolyte molded body 5. FIG.

FIG. 2 is a cross-sectional view of a state in which a slurry is poured onto the electrolyte molded body 5 of FIG. 1 and left for a certain period of time to form a fuel electrode molded body 6, and then excess slurry is removed to form a composite molded body. .

3 is a cross-sectional view of a solid electrolyte-fuel electrode composite obtained by firing after removing the mold 4 from the composite molded body of FIG. 2. FIG.

FIG. 4 is a cross-sectional view of a state in which an air electrode 9 is formed on the outside of the solid electrolyte-fuel electrode composite.

FIG. 5 is a cross-sectional view of a solid electrolyte membrane 8 manufactured by a conventional solid electrolyte fuel cell manufacturing method.

[Explanation of symbols]

4 type 5　Electrolyte molded body 6　Fuel electrode molded body 7 Fuel electrode 8 Solid electrolyte membrane 9 Air electrode

Claims (6)

[Claims] 1. A step of forming an electrolyte molded body by molding a slurry containing zirconia to which a stabilizer has been added, and containing metal or metal oxide and carbon powder on one surface of the electrolyte molded body. A step of molding the slurry to form a fuel electrode molded body to obtain a composite molded body that integrates the electrolyte molded body and the fuel electrode molded body, and firing the composite molded body to form a solid electrolyte-fuel electrode composite body. 1. A method for manufacturing a solid electrolyte fuel cell, comprising: obtaining the solid electrolyte fuel electrode, and forming an air electrode on the solid electrolyte side of the solid electrolyte-fuel electrode composite. 2. The solid electrolyte fuel according to claim 1, wherein the zirconia added with a stabilizer is composed of cubic zirconia, tetragonal zirconia, partially stabilized zirconia alone or in a mixture of multiple types. How to manufacture batteries. 3. The method for manufacturing a solid electrolyte fuel cell according to claim 1, wherein the stabilizer is an oxide of yttrium, calcium, scandium, ytterbium, neodymium, or quadrinium. 4. The method for manufacturing a solid electrolyte fuel cell according to claim 1, wherein the metal oxide or metal is an oxide of nickel or cobalt, or metal nickel or metal cobalt. 5. The method for manufacturing a solid oxide fuel cell according to claim 1, wherein the calcination is performed in an inert gas flow or a reducing atmosphere. 6. The air electrode is made of LaMnO3 or LaCoO3 doped with strontium or calcium.
, CaMnO3, the method for manufacturing a solid electrolyte fuel cell according to claim 1.