JPS63128566A - Solid electrolyte fuel battery and manufacture thereof - Google Patents

Abstract

PURPOSE:To keep air tightness and obtain a dense solid electrolyte by constituting a fine particle film comprising yttria-stabilized zirconia fine particles and a superfine particle film comprising yttria-stabilized zirconia superfine particles and allocating the fine particle film at the porous substrate side. CONSTITUTION:An about 500 mum-thick porous LaCO3 film (air electrode) 2 is formed on a porous ceramics substrate 11. A flame coating film (fine particle film) 3 of YSZ (yttriastabilized zirconia) with an average particle size of 44 mum is formed on the air electrode 2, and, furthermore, a superfine particle solid electrolyte thin film (superfine particle film) 4 is formed on the flame coating film 3. An about 150 mum-thick fuel electrode 5 comprising NiO is formed on the electrolyte thin film 4. By the arrangement, a solid electrolyte fuel battery comprising a thin film with excellent characteristics is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solid electrolyte fuel cell and a method for manufacturing the same.

[Prior Art] As is well known, solid electrolyte fuel cells generate electromotive force due to the difference in oxygen concentration between the two ends of the electrolyte, but it is necessary to make the solid electrolyte a thin film in order to lower the electrical resistance of the battery. There is. For this reason, solid electrolytes have conventionally been deposited by thermal spraying or electrochemical vapor deposition (EVD).

[Problems to be Solved by the Invention] However, the prior art has the following problems.

(1) In the case of thermal spraying; the film formation rate is fast, but the resulting film is not dense and has air permeability. Therefore, it was necessary to provide a thick membrane with a thickness of 200 to 300 m in order to suppress the permeation of hydrogen gas used as fuel.

(2>EVD method: Although a dense film can be produced, the film formation rate is slow, and it lacks mass productivity, as it requires processing one substrate tube at a time at high temperatures for a long time.

The present invention was made in view of the above circumstances, and in order to suppress gas permeability, which is a drawback of the thermal spraying method, a dense solid electrolyte membrane made of ultrafine ceramic particles is formed by a slurry method on a solid electrolyte '14 thermally sprayed membrane. The purpose of the present invention is to provide a solid electrolyte fuel cell and a method for manufacturing the same, which can be used with a thinner film thickness than conventional thermal spraying by sealing and sealing, and which has excellent properties as a solid electrolyte membrane for fuel cells. shall be.

[Means and effects for solving the problems] The invention of the present application No. 1 provides a solid electrolyte fuel cell in which an air electrode, a solid electrolyte membrane, and a fuel electrode are formed on a porous base material. It is composed of a fine particle membrane formed of fine particles of yttria-stabilized zirconia and an ultrafine particle membrane formed of ultrafine particles of yttria-stabilized zirconia, and the fine particle membrane is disposed on the porous base material side. shall be.

The invention of the present application tube 2 includes a step of forming an air electrode or a fuel electrode on a porous base material, and a step of forming a fine particle film using fine particles of ittria-stabilized zirconia on the air electrode or fuel electrode. Then, on this fine particle film, a slurry made by mixing yttria-stabilized zirconia ultrafine particles with a binder, a deflocculant, and water is applied, dried, and fired to form an ultrafine particle film, and this ultrafine particle The method further comprises the step of laminating the remaining one of the fuel electrode and the air electrode on the membrane.

The details of the present invention are as described below.

In other words, the YSZ ultrafine particles with an average particle size of 1 uI11 or less have a fast sintering rate, so they can be fired at temperatures below 1400°C, and their small particle size allows them to penetrate into the pores on the surface of the sprayed film, resulting in good adhesion. A dense solid electrolyte membrane can be formed while sealing the membrane and treating pores. In addition, the thickness of all the solid electrolyte films can be kept thinner than when all the films are formed by thermal spraying, which has the effect of lowering the internal resistance of the fuel cell.

Further, the solid electrolyte spraying conditions are preferably as follows.

(2) The average particle size of the YSZ particles is 5 to 70 mm.

Here, if the average particle size is less than 5, the fluidity of the powder is poor and it becomes difficult to feed it to a thermal spraying device.

Moreover, if it exceeds 70 um, the quality of the sprayed film will become non-uniform and the film will not be of good quality.

(2) The thickness of the sprayed film is 10 to 150 IIm.

Here, if the thickness of the sprayed film is thinner than 10 -, there is a drawback that the applied slurry penetrates into the porous electrode at the bottom. Moreover, if the film thickness is thicker than 150 mm, the electrical resistance will increase and the cost will not be reduced.

Next, the slurry preparation and firing conditions are as follows.

■The average particle size of YSZ ultrafine particles is 111! is as follows.

Here, if the particle size of the YSZ ultrafine particles is larger than 1-, it is impossible to produce a dense film that produces effects such as lowering the degree of smoldering and infiltration of slurry into the sprayed film.

(2) Use 0.01 to 3 parts of water-soluble acrylic resin as a binder.

Here, the water-soluble acrylic resin is excellent as a binder because it has good properties such as slurry viscosity and the resulting slurry is easy to apply. Further, if the amount mixed is less than 0.011 parts by weight, there is no effect, and if it exceeds 3 parts by weight, cracks will occur during firing.

■ Add 0.01 to 2 parts by weight of deflocculant.

Here, alcohol or a surfactant is suitable as the deflocculant, but if the added layer is less than 0.01 part by weight, precipitation will occur in the slurry. Further, since the effect does not increase even if the amount exceeds 2 parts by weight, a range of 0.01 to 2 parts by weight is preferable.

(2) The amount of water mixed is 20 to 60 parts by weight.

If the amount of water mixed is less than 20 parts by weight, the slurry will have a high viscosity and will be difficult to coat. On the other hand, if the amount exceeds 60 parts by weight, the fluidity of the slurry is high and the formed film becomes too thin.

(2) The slurry is fired at a temperature of 1000 to 1400°C for 0.1 to 20 hours.

The firing rate of YSZ ultrafine particles varies depending on the average particle size of the particles, but at a temperature of 1400°C, the firing rate is 0° for 1 to 5 hours, 1
At a temperature of ooo<0>C, 10 to 20 hours are required. If the firing temperature exceeds 1,400° C., problems such as cracking of other porous electrodes already formed due to thermal stress will occur, and the cost will also increase. Furthermore, when the firing temperature is lower than 1000°C, the firing time becomes very long. Further, if the firing time at each temperature is too short, sintering will not be sufficient, and if the firing time is too long, the cost will increase and it is not appropriate for operation.

■The thickness of the YSZ ultrafine particle fired solid electrolyte membrane is 10 to 15
Set to 0-.

If the film thickness is less than 10IjIIt, the film will not be uniform and the sealing process will not be sufficient. Furthermore, if the film thickness exceeds 150 mm, the gas permeability is suppressed, but when the electrical resistance increases, the cost becomes high and the advantages are reduced.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a solid electrolyte fuel cell according to the present invention.

1 in the figure is a porous ceramic base material.

On this base material 1, a porous layer of LaCO5 with a thickness of about 500-1 is placed.
A membrane (air electrode) 2 is formed. On this air electrode 2, YSZ (Ittria-stabilized zirconia) with an average particle size of 44 mm is sprayed W! A (fine particle film) 3 is formed. This thermal spraying! On top of 1II3, an ultrafine particle solid electrolyte thin film (
Ultrafine particle pus) 4 is formed. This electrolyte 114 consists of 100 parts by weight of YSZ ultrafine particles with an average particle size of 0.02 mm, 1 part by weight of a water-soluble acrylic resin (trade name: Ricaboard 5A203, manufactured by Chuo Rika Co., Ltd.) as a binder, and 1 part by weight of a water-soluble acrylic resin (trade name: Ricaboard 5A203, manufactured by Chuo Rika Co., Ltd.) as a peptizer. Stearyl alcohol 0.5 parts by weight, water 40!11
1.5% and prepared a slurry. On the electrolyte 1114 is a layer made of NiO having a thickness of approximately 150 mm.
− fuel electrode 5 is formed.

Note that 6 in the figure indicates the pores (schematically shown) of the porous ceramic base material 1. However, as a result of cutting the solid electrolyte fuel cell having such a structure and observing the cross section with an optical microscope, it was confirmed that the thickness of the sprayed film 3 was about 50 mm, and the thickness of the electrolyte thin film was about 75 mm. Ta.

According to the above embodiment, the following effects are achieved.

That is, when we measured the gas permeability of the porous ceramic substrate, the air electrode, and the case where no thermal sprayed film was formed, and the case where a dense ultrafine particle solid electrolyte thin film was attached thereon, we obtained the results shown in Figure 2. Obtained. However, the measurement method is to introduce N2 gas at a gas pressure of 300 mmHQ (in am water) into the substrate tube and the substrate tube on which various films have been formed, stop the gas introduction, and then observe the decrease in gas pressure over time. It was measured as a function. In addition, (a) in the figure is a porous alumina base tube, (b) is a case where an air electrode and a sprayed film are formed, (C
) show cases in which an ultrafine particle solid electrolyte membrane is formed on a thermally sprayed membrane by a slurry method. From the figure, it is clear that the gas permeability is significantly suppressed by coating and baking the YSzIB fine particle slurry. Therefore, airtightness can be maintained. Further, by reducing the thickness of the solid electrolyte thin film 4, the electrical resistance is also lowered, so that a dense solid electrolyte 311114 suitable for a fuel cell can be obtained.

Next, a method for manufacturing the solid electrolyte fuel cell will be described.

■First, on the porous ceramic base material 1, porous La
CoO31112 was formed to a thickness of about 500 m by a thermal spraying method, and YsZ melt 1113 having an average particle size of 44 was formed thereon.

■100 parts by weight of YSZ ultrafine particles with an average particle size of 0.02s11, 1 part by weight of water-soluble acrylic resin as a binder, 0.51 part by weight of stearyl alcohol as a deflocculant, and 40 parts by weight of water.
Parts by weight were added to prepare a slurry.

(2) Subsequently, this slurry was applied onto the thermally sprayed film 3 and then baked at 1200° C. for 5 hours to obtain an ultrafine particle solid electrolyte film 4. After the death, a fuel electrode 5 made of NiO is placed on top of it.
A solid electrolyte fuel cell was manufactured by forming a film of about 150 cells by thermal spraying. According to this method of manufacturing a solid electrolyte fuel cell, as described above, it is possible to suppress gas permeability and maintain airtightness, and also to form a compact solid electrolyte 111114.
can be obtained.

In addition, although the above example shows the case where the air electrode is located on the porous ceramic base material, this is not limited to this, and the same effect can be obtained even when the fuel electrode is located on the porous ceramic base material side as shown in FIG. You can expect.

[Effects of the Invention] As detailed above, the present invention provides a solid electrolyte fuel cell that can suppress gas permeability to maintain airtightness and provide a dense solid electrolyte membrane, and a method for manufacturing the same. can.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a solid electrolyte fuel cell according to an embodiment of the present invention, and FIG. 2 is a characteristic diagram showing the relationship between gas pressure and time.
FIG. 3 is a sectional view of a solid electrolyte fuel cell according to another embodiment of the present invention. 1... Porous ceramic base material, 2... Porous La
CoO3 (air electrode), 3... thermal spray film (fine particle model),
4...Ultrafine particle solid electrolyte thin film (ultrafine particle membrane), 5
... fuel electrode, 6... pores. Applicant Sub-Attorney Patent Attorney Takehiko Suzue Time (Happy) Figure 2 Figure 3 Procedural Amendment 1, Case Description Patent Application No. 274323/1982 Title of Invention Solid Electrolyte Fuel Cell and Process for Manufacturing the Same 3, Amendment Patent applicant (820) Mitsubishi Heavy Industries, Ltd. 4, sub-agent UBE Building 7, 3-7-2 Kasumigaseki, Chiyoda-ku, Tokyo;
Contents of the amendment (1) In the specification section, page 6, line 12, the phrase "exceeding" is corrected to "exceeding". (2) In the specification section, page 7, line 17, the phrase "when increasing" is corrected to "as it increases." (3) On page 9, line 11 of the statement box, “mmHg (mm
Correct the text "rmmAq (mm underwater)" to "rmmAq (mm underwater)". (4) In line 13 of the same page of the specification, the phrase "as a function" is corrected to "as a function." (5) Figures 1 and 3 are corrected as shown in the attached sheet. Figure 1 Figure 3

Claims (2)

[Claims] (1) In a solid electrolyte fuel cell in which an air electrode, a solid electrolyte membrane, and a fuel electrode are formed on a porous base material, the solid electrolyte membrane is replaced with a fine particle membrane formed of fine particles of yttria-stabilized zirconia and yttria-stabilized zirconia. 1. A solid electrolyte fuel cell comprising an ultrafine particle membrane made of ultrafine zirconia particles, the fine particle membrane being disposed on the porous base material side. (2) a step of forming an air electrode or a fuel electrode on a porous base material; a step of forming a fine particle film using fine particles of yttria-stabilized zirconia on the air electrode or fuel electrode;
On this fine particle film, a slurry made by mixing yttria-stabilized zirconia ultrafine particles with a binder, a deflocculant, and water is applied, dried, and fired to form an ultrafine particle film; A method for producing a solid electrolyte fuel cell, comprising the steps of: laminating the remaining one of the fuel electrode or the air electrode.