JP3349382B2 - Method for producing solid electrolyte type electrochemical cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a solid oxide electrochemical cell used in such solid oxide fuel cells and solid oxide steam electrolytic apparatus.

[0002]

2. Description of the Related Art FIG. 2 shows a main structure of a conventional electrochemical cell of a solid oxide fuel cell of a cylindrical series type. In FIG. 2, 21 is a base tube, 22 is a fuel electrode, 23 is a solid electrolyte,
24 is an air electrode and 25 is an interconnector.

[0003] The base tube 21 is porous and has a cylindrical shape. The fuel electrode 22 is porous, and the base tube 2
A plurality of films are formed on one at predetermined intervals. Solid electrolyte 2
Numerals 3 are formed on the fuel electrode 22 and between one adjacent fuel electrode 22 by a predetermined length. The air electrode 24 is porous and is formed on the solid electrolyte 23. The interconnector 25 electrically connects a single element including the fuel electrode 22, the solid electrolyte 23, and the air electrode 24, that is, connects the fuel electrode 22 of one single element and the air electrode 24 of the other single element. Films are formed between the single elements so as to be electrically connected to the solid electrolytes 23 of both the single elements while being in contact with each other.

In such an electrochemical cell, the whole is heated to a predetermined temperature (about 800 to 1000 ° C.), and while the fuel gas 11 such as hydrogen or methane is supplied into the base tube 21, the base tube is heated. 21, that is, the cathode 24
An oxidizing gas 12, such as air or oxygen, is supplied to the outside of the device, and the gases 11, 12 are electrochemically reacted to generate electric power.

The electrochemical cell of the solid electrolyte type steam electrolyzer has the same structure as the above-mentioned electrochemical cell of the solid electrolyte type fuel cell. When air is supplied to the outside of the fuel cell 21 and a voltage is applied, water vapor is electrolyzed to obtain hydrogen.

In these electrochemical cells, the hermeticity of the solid electrolyte 23 is increased as much as possible in order to make the electromotive force and the hydrogen yield as close to theoretical values as possible. In order to obtain such a highly airtight solid electrolyte 23, EV
D (Electro-chemical Vaper Diposition) method, CVD (C
The solid electrolyte 23 and the like are formed on the substrate tube 21 by a method such as a chemical vapor deposition method or a thermal spraying method.

[0007] Such a solid electrolyte 2 having high airtightness
Among the methods for forming a film of No. 3 or the like, an organic vehicle comprising a binder, a solvent, and raw material powders such as the fuel electrode 22 and the solid electrolyte 23 are mixed to prepare a slurry for each raw material powder, and these slurries are used as base materials. A screen printing method of forming a film on the base tube 21 by printing the tube 21 through a screen mesh has been actively studied in recent years because it has high production efficiency and can greatly reduce the production cost. In this screen printing method, the film thickness that can be formed by one printing is 50 to
Since it is about 100 μm, when forming a film with a film thickness of 100 μm or more, it is necessary to perform printing several times, but since a single printing speed (film forming speed) is extremely high, a thick film is used. However, it can be produced efficiently.

[0008]

In the conventional electrochemical cell as described above, the fuel electrode 22 needs to have a thickness of 100 μm or more, and the solid electrolyte 23 needs to have a thickness of several μm to several tens μm. If such an electrochemical cell is to be produced by the screen printing method as described above, it is difficult for the mesh or squeegee rubber to follow between the adjacent fuel electrodes 22 (stepped portion), so that the solid electrolyte 23 is uniformly applied to the stepped portion. And the non-film-formed portion without the solid electrolyte 23 is generated along the step portion (even if printing is further continued in the same place, the step is further increased, and as a result, the non-film-formed portion does not disappear. .) There was a case.

In this manner, the solid electrolyte 23
In the solid oxide fuel cell, the fuel gas 11 and the oxidizing gas 12 flow so as to be in direct contact with each other without passing through the solid electrolyte 23, so that the electromotive force is significantly reduced. In addition to the risk that the fuel cell 11 may be damaged due to the combustion of the fuel gas 11 due to the contact between the fuel gas 11 and the oxidizing gas 12, the cell may be significantly damaged locally.

[0010] Such an unformed portion may occur when the interconnector 24 is formed on the step between the adjacent solid electrolytes 23.

In addition to the electrochemical cell of the solid electrolyte type steam electrolyzer, the solid electrolyte type electrochemical cell in which a film is formed by printing on a plate-like substrate,
In some cases, the same problem as described above occurs.

[0012] For this reason, the present invention has an object to provide a method of <br/> producing solid oxide electrochemical cell having a less susceptible structure of ungrown portion.

[0013]

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a method for manufacturing a solid electrolyte type electrochemical cell according to the present invention comprises the steps of: In a method of manufacturing a solid electrolyte type electrochemical cell by printing the slurry of the electrolyte multiple times and printing the slurry of the second electrode, the position and the solid electrolyte where the slurry of the first electrode is printed by overlapping The printing position is shifted by overlapping the slurry.

[0015]

The embodiment in which the manufacturing method of the embodiment of the invention solid electrolyte electrochemical cell according to the present invention is applied to the manufacture of electrochemical cells of the solid oxide fuel cell of the cylinder series connection type with reference to FIG. 1 explained I do. FIG. 1 is a schematic structural view of a main part of the manufactured electrochemical cell.

In FIG. 1, 1 is a base tube, 2 is a fuel electrode as a first electrode, 3 is a solid electrolyte, 4 is an air electrode as a second electrode, and 5 is an interconnector.

The base tube 1 is porous and has a cylindrical shape. The fuel electrode 2 is porous, and a plurality of the fuel electrodes 2 are formed on the base tube 1 at predetermined intervals, and stepped portions 2a each having a step shape are formed on both ends thereof. The solid electrolyte 3 is formed on the fuel electrode 2 and between one adjacent fuel electrode 2 with a predetermined length, and a step 3a having a step shape is formed on the step 2a of the fuel electrode 2. Have been. The air electrode 4 is porous and is formed on the solid electrolyte 3. The interconnector 5 electrically connects a single element including the fuel electrode 2, the solid electrolyte 3, and the air electrode 4, that is, the fuel electrode 2 of one of the single elements.
The step 2a and the air electrode 4 of the other single element are electrically connected to the step 3a of the solid electrolyte 3 of the other single element and the end of the solid electrolyte 3 of the one single element. As described above, a film is formed between the single elements.

In FIG. 1, reference numeral 11 denotes a fuel gas such as hydrogen or methane, and reference numeral 12 denotes an oxidizing gas such as air or oxygen.

Next, a method for manufacturing an electrochemical cell having such a structure will be described. The fuel electrode 2 is placed on the outer peripheral surface of the base tube 1 so that the outermost one becomes gradually smaller in the longitudinal direction of the base tube 1.
The slurry of the raw material powder is superposed a plurality of times and screen-printed, so that the fuel electrode 2 having a stepped portion 2a having a step-like shape at both ends in the longitudinal direction of the base tube 1 is formed along a predetermined length along the longitudinal direction of the base tube 1. A plurality of films are formed at intervals (fuel electrode film forming process). The outer circumferential surface of the fuel electrode 2 and the stepped portion 2a of the fuel electrode 2 are so arranged that the size of the base tube 1 on the stepped portion 2a of the fuel electrode 2 in the longitudinal direction becomes gradually smaller as it is located on the outer side. The slurry of the raw material powder of the solid electrolyte 3 is overlapped a plurality of times and screen-printed, so that the solid electrolyte 3 having the step portion 3a in a step shape on the step portion 2a of the fuel electrode 2 is formed on the fuel electrode 2 respectively. A film is formed (solid electrolyte film forming step).

Subsequently, adjacent step portions 2 between the fuel electrode 2 and the solid electrolyte 3 are connected so as to connect the adjacent solid electrolytes 3.
The interconnector 5 is formed into a film by screen printing a slurry of the raw material powder of the interconnector 5 between a and 3a (interconnector film forming step). Next, a slurry of the raw material powder for the air electrode 4 is screen-printed on the exposed outer peripheral surface of the solid electrolyte 3 and the outer peripheral surface of the interconnector 5 to form the air electrode 5 (air electrode film forming step).

In other words, by shifting the printing position of the slurry of the fuel electrode 2, the step portion 2 a having a step shape is formed at the end of the fuel electrode 2, and then the slurry of the solid electrolyte 3 is printed in an overlapping manner. By displacing the position, a stepped portion 3a having a stepped shape following the stepped portion 2a of the fuel electrode 2 is formed at the end of the solid electrolyte 3, and the slurry of the interconnector 5 is printed on the stepped portions 2a and 3a. I did it.

Therefore, even in the screen printing of the slurry of the solid electrolyte 3 or the screen printing of the slurry of the interconnector 5 between the adjacent anodes 2, the mesh or the squeegee rubber can easily follow along the gap. The solid electrolyte 3 and the interconnector 5 can be reliably formed between them.

Therefore, according to the present embodiment, the occurrence of unformed portions of the solid electrolyte 3 and the interconnector 5 is significantly reduced, so that the fuel gas 11 and the oxidizing gas 12 flow in direct contact. This can prevent the electromotive force from remarkably lowering and damage due to local remarkable heat generation.

In the fuel electrode 2 having the stepped portion 2a as described above, since the film thickness on the end side is reduced, the conductivity is lowered, and the electromotive force may be reduced. If the magnitude of the deviation is 1 mm or less, the reduction in the electromotive force due to the occurrence of the non-film-formed portion is larger than the reduction in the electromotive force due to the above-described decrease in the conductivity. Absent.

In the present embodiment, the first electrode is used as the fuel electrode 2 and the second electrode is used as the air to flow the fuel gas 11 inside the base tube 1 and the oxidizing gas 12 outside the base tube 1. Although the electrode 4 is used, when an oxidizing gas flows inside the base tube and a fuel gas flows outside the base tube 1,
The first electrode may be an air electrode and the second electrode may be a fuel electrode.

In this embodiment, a case where the present invention is applied to a cell of a solid electrolyte fuel cell of a cylindrical series type has been described. However, a solid electrolyte electrochemical cell formed by printing on a plate-like substrate to form a film or a solid electrolyte fuel cell The same can be applied to the electrochemical cell of the steam electrolyzer in the same manner as in the above-described case.

[0027]

EXAMPLES To confirm the effect of the manufacturing method of the solid oxide electrochemical according to the invention was carried out as follows confirmation experiments.

[Production of each slurry] The composition of the slurry of the fuel electrode is shown in Table 1, the composition of the slurry of the solid electrolyte is shown in Table 2, the slurry of the interconnector is shown in Table 3, and the composition of the slurry of the air electrode is shown in Table 1. It is shown in Table 4.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

[Table 4]

First, the main component is added to ethanol, mixed and melted in a ball mill for 15 hours, then heated under reduced pressure (100 torr) by a rotary evaporator for 2 hours (60 ° C.) to remove ethanol, and further heated in a drier for 1 hour. (1
Dry at 50 ° C). Next, an organic solvent such as a solvent mixture such as solvent naphtha, an organic vehicle in which a binder such as polyacryl is dissolved, and a dispersant are added and mixed for several minutes. ) Is sufficiently dispersed.

[Production of Substrate] CSZ (calcia-stabilized zirconia) was kneaded with an organic binder or the like and extruded into a tube.

[Manufacture of Electrochemical Cells under Various Conditions] Four samples of electrochemical cells were manufactured under the respective conditions of Examples 1 to 5 and Comparative Examples 1 and 2 shown below.

<Example 1> A fuel electrode film forming step A fuel electrode slurry was printed on the outer peripheral surface of the base tube with a commercially available screen printing machine (using a polyamide-based 100 mesh screen mesh), and dried for 10 minutes with a dryer. Degree heating (70
℃) After drying, 0. 0 in the longitudinal direction (axial direction) of the base tube.
By repeating printing of the anode slurry again by shifting it by 25 mm and drying it again three times, a fuel electrode having a step-like step on the longitudinal end side of the base tube is formed into a film (total of four times printing, Dried). The formed fuel electrode has a dry film thickness of about 200 μm.

Solid electrolyte film forming step The solid electrolyte slurry is printed and dried in the same manner as in the fuel electrode film forming step, and then dried in the longitudinal direction (axial direction) of the base tube.
By printing the solid electrolyte slurry again by shifting it by 5 mm, and drying it again, a solid electrolyte having a stepped step portion on the longitudinal end side of the base tube is formed into a film (two times of printing and drying).
did.

An interconnector film forming process was performed by printing and drying an interconnector slurry in the same manner as in the conventional interconnector film forming process, thereby forming an interconnector film (one printing and drying in total).

Air electrode film formation step An air electrode film was formed by printing and drying an air electrode slurry in the same manner as in the conventional air electrode film formation step.

<Embodiment 2> A fuel electrode film forming step A fuel electrode slurry was printed and dried by the same method as in the fuel electrode film forming step of Example 1, and then the fuel electrode slurry was printed in the longitudinal direction (axial direction) of the base tube. By repeating printing of the anode slurry again by shifting by 0.5 mm and drying again three times, a fuel electrode having a stepped step portion at the longitudinal end side of the base tube is formed into a film (total of four printings). , Dried). The formed fuel electrode has a dry film thickness of about 200 μm.

Solid electrolyte film forming step The solid electrolyte slurry is printed and dried in the same manner as in the solid electrolyte film forming step of Example 1, whereby a solid having a stepped step at the longitudinal end of the base tube is obtained. An electrolyte was deposited.

An interconnector film forming process was performed by printing and drying an interconnector slurry in the same manner as in the interconnector film forming process of Example 1.

Air electrode film formation step An air electrode film was formed by printing and drying an air electrode slurry in the same manner as in Example 1.

<Embodiment 3> Fuel electrode film forming step After the anode slurry was printed and dried in the same manner as in the fuel electrode forming step of Example 1, one was formed in the longitudinal direction (axial direction) of the base tube. The fuel electrode slurry is printed again by shifting it by 0.0 mm, and drying is repeated again three times, thereby forming a fuel electrode having a stepped step on the longitudinal end side of the base tube (a total of four times printing). , Dried). The formed fuel electrode has a dry film thickness of about 200 μm.

Solid electrolyte film-forming step The solid electrolyte slurry is printed and dried in the same manner as in the solid electrolyte film-forming step of Example 1 to obtain a solid having a stepped step at the longitudinal end of the base tube. An electrolyte was deposited.

An interconnector film was formed by printing and drying an interconnector slurry in the same manner as in the interconnector film forming step of the first embodiment.

Air electrode film formation step The air electrode slurry was printed and dried in the same manner as in the air electrode film formation step of Example 1 to form an air electrode film.

<Fourth Embodiment> A fuel electrode forming step A fuel electrode slurry is printed and dried in the same manner as in the fuel electrode forming step of the first embodiment, so that a step-like shape is formed on the longitudinal end side of the base tube. A fuel electrode having a step was formed.

Solid electrolyte film-forming step A solid electrolyte slurry was printed and dried in the same manner as in the solid electrolyte film-forming step of Example 1, and then shifted by 0.25 mm in the longitudinal direction (axial direction) of the base tube. By printing the electrolyte slurry again and drying it again, a solid electrolyte having a step-like step on the longitudinal end side of the base tube was formed into a film (two times of printing and drying).

An interconnector film formation step was performed by printing and drying an interconnector slurry in the same manner as in the interconnector film formation step of Example 1.

Air electrode film formation step An air electrode film was formed by printing and drying the air electrode slurry in the same manner as in the air electrode film formation step of Example 1.

Fifth Embodiment Anode Formation Step A fuel electrode slurry is printed and dried in the same manner as in the first embodiment, so that a step-like shape is formed on the end of the base tube in the longitudinal direction. A fuel electrode having a step was formed.

Solid electrolyte film forming step The solid electrolyte slurry was printed and dried in the same manner as in the solid electrolyte film forming step of Example 1, and then shifted by 0.1 mm in the longitudinal direction (axial direction) of the base tube to form a solid. By printing the electrolyte slurry again and drying it again, a solid electrolyte having a step-like step on the longitudinal end side of the base tube was formed into a film (two times of printing and drying).

An interconnector film was formed by printing and drying an interconnector slurry in the same manner as in the interconnector film forming step of the first embodiment.

Air electrode film formation step An air electrode film was formed by printing and drying the air electrode slurry in the same manner as in the air electrode film formation step of Example 1.

<Comparative Example 1> Fuel electrode film forming step Printing and drying of the fuel electrode slurry in the same manner as in the fuel electrode film forming step of Example 1 was performed in the longitudinal direction (axial direction) of the base tube.
By repeating the process four times without shifting, a fuel electrode similar to the conventional one was formed.

Solid electrolyte film forming step By printing and drying a solid electrolyte slurry in the same manner as in the solid electrolyte film forming step of Example 1, a solid having a stepped step at the longitudinal end of the base tube is formed. An electrolyte was deposited.

An interconnector film formation step An interconnector film was formed by printing and drying an interconnector slurry in the same manner as in the interconnector film formation step of Example 1.

Air electrode film formation step An air electrode film was formed by printing and drying the air electrode slurry in the same manner as in the air electrode film formation step of Example 1.

<Comparative Example 2> Fuel electrode film forming step A fuel electrode slurry was printed and dried in the same manner as in the fuel electrode film forming step of Example 1, so that a stepwise shape was formed on the longitudinal end of the base tube. A fuel electrode having a step was formed.

Solid electrolyte film forming step Printing and drying of the solid electrolyte slurry in the same manner as in the solid electrolyte film forming step of Example 1 are repeated twice without shifting in the longitudinal direction (axial direction) of the base tube. As a result, a solid electrolyte similar to the conventional one was formed.

The interconnector film was formed by printing and drying the interconnector slurry in the same manner as in the interconnector film forming step of the first embodiment.

Air electrode film formation step An air electrode film was formed by printing and drying the air electrode slurry in the same manner as in the air electrode film formation step of Example 1.

[Experimental method] <Confirmation of film formation state> The appearance of the electrochemical cell printed and formed as described above is examined to confirm the film formation state (unformed portion, presence or absence of pinholes, etc.). did.

<Calculation of Gas Leak Rate> After firing the electrochemical cell whose film formation state was confirmed, hydrogen gas was passed through the inside of the base tube, and the amount of hydrogen gas leaked to the outside was measured by gas chromatography to measure gas leak. The rate was calculated. In addition,
It has been empirically found that there is no particular problem if the gas leak rate is 10 vol.% Or less (if it exceeds 10 vol.%, The open circuit voltage is reduced and the power generation performance is likely to be insufficient). I have.

[Experimental Results] Table 5 shows the experimental results.

[0067]

[Table 5]

As can be seen from Table 5, it was confirmed that the samples of Examples 1 to 5 had no unformed portions and pinholes, and had no problem in the film formation state. Example 2,
3,5 samples (all deviations are 0.5mm
Above), the average gas leak rate was around 5 vol.%, And it was confirmed that there was no problem. However, the samples of Examples 1 and 4 (having a size of displacement of 0.25 mm) were used. Since the average gas leak rate was about 8 vol.%, Which was a slightly large value, a power generation performance test was performed as an additional confirmation experiment, and it was confirmed that there was no particular problem.

On the other hand, in the sample of Comparative Example 1, an unformed portion of the solid electrolyte was confirmed at a plurality of portions, and the average gas leak rate was 35 vol.%. Further, in the sample of Comparative Example 2, the unfilmed portion of the interconnector was confirmed at a plurality of locations,
The average gas leak rate was 25 vol.%.

From the above, according to the present invention , it was confirmed that the occurrence of unformed portions of the solid electrolyte and the interconnector was significantly reduced, and the direct contact between gases could be significantly reduced.

The above-described shift width in the longitudinal direction of the base tube in printing the fuel electrode slurry or the solid electrolyte slurry a plurality of times is preferably within a range of 0.25 to 1 mm. More preferably, it is within the range of 0.5 to 1 mm. Because the shift width is 0.2
If it is smaller than 5 mm, the above-mentioned effects due to the features of the present invention are less likely to be exhibited.
If it is smaller than the above, as can be seen from the above-described embodiment, the above-mentioned effects by the features of the present invention can be obtained, but the degree is small, and if it is larger than 1 mm, the overall average thickness becomes too small and the electric conductivity becomes too small. This is because there is a possibility that the electromotive force is excessively reduced, and the electromotive force is reduced more than the electromotive force is reduced due to the occurrence of the unformed portion.

[0072]

The solid electrolyte type electrochemical cell according to the present invention
In the manufacturing method, a step-shaped step is formed at the end of the first electrode and the solid electrolyte by shifting the position where the slurry of the first electrode is overprinted and the position where the slurry of the solid electrolyte is overprinted. In this way, when printing, the mesh or squeegee rubber or the like can easily follow along the end portion, so that the solid electrolyte or the like can be reliably formed at the portion, and the solid electrolyte or the like can be formed. The occurrence of unformed portions is significantly reduced.

[Brief description of the drawings]

FIG. 1 shows the production of a solid electrolyte type electrochemical cell according to the present invention .
Method of electrochemical cell for solid oxide fuel cell with cylindrical series
FIG. 2 is a main part structural view of an electrochemical cell manufactured according to an embodiment when applied to manufacture of a cell.

FIG. 2 shows a conventional battery of a solid oxide fuel cell of a cylindrical series type .
It is a principal part structural diagram of a chemical cell .

[Description of Signs] 1 base tube 2 fuel electrode 2a step 3 solid electrolyte 3a step 4 air electrode 5 interconnector 11 fuel gas 12 oxidizing gas

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-185882 (JP, A) JP-A-63-147324 (JP, A) JP-A-64-66953 (JP, A) JP-A-2- 232924 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 8/02 H01M 8/10-8/12 H01M 4/86-4/98 H01L 21/88 H01L 21/302

Claims (1)

(57) [Claims] 1. A slurry of a first electrode is stacked on a substrate a plurality of times.
And then printing the solid electrolyte slurry multiple times
The solid electrolyte is printed by printing the slurry of the second electrode.
In the method for producing a type electrochemical cell, the first electrode
And the position where the slurry is overlapped and printed
It is characterized in that the printing position is shifted by overlapping the quality slurry.
A method for producing a solid electrolyte type electrochemical cell.