JPH05101841A - Manufacture of solid electrolytic fuel cell - Google Patents

Abstract

PURPOSE:To simplify the manufacturing processes by pouring a 1st, 2nd, and 3rd slurry into a form, and forming an air electrode molding, an electrolyte molding, and a fuel electrode molding. CONSTITUTION:A 1st slurry including metal oxide is poured into a form having water absorptiveness to form an air electrode molding 5, and thereover a 2nd slurry containing zirconia with stabilizer as additive is poured in so as to form an electrolyte molding 6, and further thereover a 3rd slurry including metal oxide or a metal is poured in to form an air electrode molding 7, which are dried and get rid of the form 4, followed by baking, and a solid electrolyte fuel cell is accomplished which has an air electrode 8 on the outside, a solid electrolyte film 9 in the middle, and a fuel electrode 10 on the inside. Accordingly the air electrode 8, electrolyte film 9, and fuel electrode 10 are constructed in a single piece, wherein the thickness is controllable to any desired value, which can provide the resultant fuel cell with a high operating performance.

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 solid oxide fuel cell.

[0002]

2. Description of the Related Art As solid electrolyte fuel cells, phosphoric acid fuel cells, flat-plate type fuel cells having a structure similar to molten carbonate fuel cells, monolithic type proposed by Argonne National Laboratory in the United States, Japanese electronic technology comprehensive The cylindrical multi-element type being developed by the laboratory and the cylindrical single-element type proposed by Westinghouse, Inc. in the United States are known, but at present, Westin is easy to gas seal at high temperature and easy to construct a stack. Guhouse's cylindrical single element type is receiving attention.

As a method for producing a solid electrolyte used in such a solid electrolyte fuel cell, there are a plasma spraying method, a chemical vapor deposition method (CVD), an electrochemical vapor deposition method (EVD), a thermal decomposition method of an organic metal zirconium salt, and the like. Although known, the plasma spraying method and the electrochemical vapor deposition method (EVD) are the only methods for obtaining a dense solid electrolyte membrane.

Further, as a method of forming the dense solid electrolyte membrane as described above, an attempt has been made to make the stabilized zirconia powder 3 into a slurry, apply the slurry to the base material 1 and fire the slurry as shown in FIG. ..

[0005]

In the former manufacturing method described above, an expensive manufacturing apparatus is required, and it takes a long time to perform masking for forming a portion requiring the solid electrolyte membrane and a portion not requiring the solid electrolyte membrane. Therefore, there is a problem in mass productivity of the battery.

Further, in the latter manufacturing method, the particles of the stabilized zirconia powder 3 contract during firing, so that cracks 2 occur in the solid electrolyte membrane 9 formed on the base material 1 or the solid electrolyte membrane 9 is formed. There was a problem of peeling.

[0007]

In order to solve the above problems, the present invention provides a surplus slurry after casting a first slurry containing a metal oxide into a mold having water absorbency to form an air electrode formed body. And a step of removing a surplus of the slurry after the second slurry containing zirconia added with a stabilizer is poured onto the air electrode molded body to form an electrolyte molded body, and a metal oxide or metal A step of pouring a third slurry containing the above into the above-mentioned electrolyte molded body to form a fuel electrode molded body, removing excess slurry to form a three-layer molded body, and drying the three-layer molded body to obtain a mold. Is removed and then calcined to form an air electrode, a solid electrolyte membrane, and a fuel electrode.

[0008]

As described above, according to the present invention, the first, second, and third slurries are poured into a mold having water absorbency to form an air electrode molded body,
Since the electrolyte molded body and the fuel electrode molded body are formed and are fired at the same time, a dense solid electrolyte membrane and a porous air electrode and fuel electrode can be easily formed, and the thickness thereof is also the slurry. It can be controlled arbitrarily depending on the flowing time.

The air electrode formed body composed of the first slurry and the fuel electrode formed body composed of the third slurry may be fired to increase the strength of the air electrode and the fuel electrode. It is possible to act as a base material.

[0010]

EXAMPLE FIG. 1 is a cross-sectional view of a mold 4 used in the method for manufacturing a solid oxide fuel cell of the present invention, which is made of a material having a water absorbing property such as gypsum.

FIG. 2 shows a zirconia powder obtained by adding LaMnO ₃ containing strontium as a metal oxide to the mold 4 and adding yttria as a stabilizer.
FIG. 3 is a cross-sectional view of a state in which a surplus slurry is removed after a first slurry composed of water, a dispersant, a binder, and a defoaming agent is poured and left for a certain period of time to form an air electrode molded body 5.

FIG. 3 shows a second layer consisting of zirconia powder added with yttria as a stabilizer, water, a dispersant, a binder and a defoaming agent until the air electrode molded body 5 dries.
FIG. 4 is a cross-sectional view showing a state in which the excess slurry is removed after the slurry of 1 is poured onto the air electrode molded body 5 and left for a certain period of time to form the electrolyte molded body 6.

FIG. 4 shows a zirconia powder to which nickel oxide as a metal oxide and yttria as a stabilizer are added before the electrolyte molded body 6 dries.
A cross-sectional view of a state in which a third slurry composed of water, a dispersant, a binder, and a defoaming agent is poured onto the electrolyte molded body 6 and left for a certain period of time to form a fuel electrode molded body 7, and then excess slurry is removed. That is, it is a cross-sectional view of a three-layer molded body.

In FIG. 5, the three-layer molded body of FIG. 4 is dried to remove the mold 4 and then fired to form a porous air electrode 8 on the outside, a dense solid electrolyte membrane 9 in the middle, and a porous solid electrolyte membrane on the inside. FIG. 1 is a cross-sectional view of a state where a fuel electrode 10 is formed, that is, a cross-sectional view of a solid oxide fuel cell obtained by the manufacturing method of the present invention.

When the solid electrolyte fuel cell thus obtained as shown in FIG. 5 is heated from an operating temperature of 700 ° C. to 1000 ° C. and air is supplied to the air electrode 8 side and fuel is supplied to the fuel electrode 10 side, Thereby, nickel oxide in the fuel electrode 10 is reduced.

Therefore, when the fuel electrode 10 and the air electrode 8 of FIG. 5 are connected to an external circuit, the oxygen taken in from the air electrode 8 takes in the electrons supplied from the external circuit to become oxygen ions, and these oxygen ions are It passes through the solid electrolyte membrane 9 and reaches the interface between the solid electrolyte membrane 9 and the fuel electrode 10.

On the other hand, hydrogen or carbon monoxide that has diffused in the fuel electrode 10 is present at this interface, and the hydrogen or carbon monoxide reacts with the oxygen ions to generate water vapor and carbon dioxide. Since electrons are emitted to the external circuit, the air electrode 8 is the positive electrode and the fuel electrode 1 is in the external circuit.
An electromotive force with 0 as a negative electrode is generated, and the battery functions.

Although the above description is for manufacturing a three-layer molded body having a cylindrical mold 4, if the mold 4 as shown in FIG. 6 is used, a three-layer molded body of a flat plate type can be obtained. It goes without saying that a monolithic three-layer molded body can be manufactured by using the mold 4 as shown in FIG.

[0019]

As described above, according to the present invention, the dense solid electrolyte membrane 9, the porous fuel electrode 10 and the air electrode 8 can be easily formed, and the thickness thereof is the first, second and third slurries. The resistance and mechanical strength of the solid electrolyte membrane 9 can be easily controlled, and the performance of the solid electrolyte fuel cell can be improved.

Further, since the slurry is poured into the water-absorbing mold 4 to form the cathode molded body 5, the electrolyte molded body 6, and the anode molded body 7, the mold 4 is removed and fired, so that the manufacturing process is performed. Can be simplified.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mold 4 used in the method for producing a solid oxide fuel cell of the present invention.

FIG. 2 is a cross-sectional view showing a state in which a surplus slurry is removed after the first slurry is poured into the mold 4 of FIG. 1 and left for a certain period of time to form an air electrode molded body 5.

FIG. 3 is a plan view of the electrolyte molded body 6 after pouring a second slurry on the air electrode molded body 5 of FIG.
It is sectional drawing in the state which removed the excessive slurry.

FIG. 4 is a diagram showing a structure of a fuel electrode compact 7 after pouring a third slurry on the electrolyte compact 6 of FIG.
It is sectional drawing of the state which removed the excessive slurry and made it into a three-layer molded body.

FIG. 5 is a cross-sectional view of a solid oxide fuel cell obtained by the manufacturing method of the present invention.

FIG. 6 is a cross-sectional view of a three-layer molded body obtained in another example of the present invention.

FIG. 7 is a sectional view of a three-layer molded body obtained in another example of the present invention.

FIG. 8 is a cross-sectional view of a solid electrolyte membrane 9 manufactured by a conventional method for manufacturing a solid electrolyte fuel cell.

[Explanation of symbols]

 4 type 5 air electrode molded body 6 electrolyte molded body 7 fuel electrode molded body 8 air electrode 9 solid electrolyte membrane 10 fuel electrode

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[Procedure amendment]

[Submission date] September 21, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

[0007]

In order to solve the above-mentioned problems, the present invention comprises the steps of pouring a first slurry containing a metal oxide into a mold having a water-absorbing property to form an air electrode formed body, and Second containing zirconia with added agent
The step of pouring the slurry of 1. above onto the cathode molded body to form an electrolyte molded body, and pouring a third slurry containing a metal oxide or a metal onto the electrolyte molded body to form a fuel electrode molded body, and air. From the step of forming a three-layer molded body in which the electrode molded body, the electrolyte molded body, and the fuel electrode molded body are integrated, and the step of firing the three-layer molded body to form an air electrode, a solid electrolyte membrane, and a fuel electrode. It is characterized by becoming.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

FIG. 2 shows a zirconia powder obtained by adding LaMnO ₃ containing strontium as a metal oxide to the mold 4 and adding yttria as a stabilizer.
FIG. 3 is a cross-sectional view of a state in which a surplus slurry is removed after a first slurry composed of water, a dispersant, a binder, and a defoaming agent is poured and left for a certain period of time to form an air electrode molded body 5. In addition, LaMnO ₃ for forming this air electrode molded body 5
By increasing the particle size of the powder and zirconia powder,
A porous air electrode can be formed by firing described below.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

FIG. 3 shows a second layer consisting of zirconia powder added with yttria as a stabilizer, water, a dispersant, a binder and an antifoaming agent until the air electrode molded body 5 is dried.
FIG. 4 is a cross-sectional view of a state in which the excess slurry is removed after the slurry of FIG. In addition, the second for forming the electrolyte molded body 6
Needless to say, the above slurry and the first slurry for forming the air electrode molded body 5 do not have to be the same, but the second slurry contains a zirconia powder having a small particle size and is dispersed. By adding the agent, a dense solid electrolyte membrane can be formed by firing described later. Also, by increasing the cubic zirconia in the zirconia powder, the electric resistance of the solid electrolyte membrane can be reduced, and by increasing the tetragonal zirconia, the strength of the solid electrolyte membrane can be increased.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

FIG. 4 shows a zirconia powder to which nickel oxide as a metal oxide and yttria as a stabilizer are added before the electrolyte molded body 6 dries.
A cross-sectional view of a state where a third slurry composed of water, a dispersant, a binder, and a defoaming agent is poured onto the electrolyte molded body 6 and left for a certain period of time to form a fuel electrode molded body 7, and then excess slurry is removed, That is, it is a cross-sectional view of a three-layer molded body. The third slurry for forming the fuel electrode compact 7 and the first and second slurries for forming the air electrode compact 5 and the electrolyte compact 6 do not have to be the same. Needless to say, by increasing the particle size of the zirconia powder or the nickel oxide powder, it is possible to form a porous fuel electrode by firing described later.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

[0019]

As described above, according to the present invention, the dense solid electrolyte membrane 9, the porous fuel electrode 10 and the air electrode 8 can be easily formed, and the thickness thereof is the first, second and third slurries. It is possible to control the resistance and mechanical strength of the solid electrolyte membrane 9 by changing the kind and amount of the stabilizer added to the zirconia powder in the slurry. Therefore, a high performance solid electrolyte fuel cell can be easily obtained.

Claims (5)

[Claims] 1. A step of pouring a first slurry containing a metal oxide into a mold having a water absorbing property to form an air electrode molded body and removing excess slurry, and containing zirconia to which a stabilizer is added. A step of pouring the second slurry to the cathode molded body to form an electrolyte molded body and then removing excess slurry; and a third slurry containing a metal oxide or a metal on the electrolyte molded body. A step of pouring into a fuel electrode molded body to remove excess slurry to form a three-layer molded body, and drying the three-layer molded body to remove the mold and then firing to form an air electrode, a solid electrolyte membrane, A method for manufacturing a solid oxide fuel cell, comprising the steps of forming a fuel electrode. 2. The metal oxide contained in the first slurry is LaMn to which a rare earth or alkaline earth metal is added.
The method for producing a solid oxide fuel cell according to claim 1, wherein the solid electrolyte fuel cell is O ₃ , LaCoO ₃ , CaMnO ₃ , or LaCrO ₃ . 3. The solid according to claim 1, wherein the zirconia contained in the second slurry comprises cubic zirconia, tetragonal zirconia, partially stabilized zirconia alone or as a mixture of plural kinds. Method for manufacturing electrolyte fuel cell. 4. The method for producing a solid electrolyte fuel cell according to claim 1, wherein the stabilizer is an oxide of yttrium, calcium, scandium, ytterbium, neodymium, or gadolinium. 5. The solid electrolyte fuel cell according to claim 1, wherein the metal oxide or metal contained in the third slurry is nickel or cobalt oxide or metal nickel or metal cobalt. Production method.