JP5249643B2 - Solid oxide fuel cell manufacturing method and solid oxide fuel cell manufactured using the same - Google Patents

Description

  The present invention relates to a method for producing a solid oxide fuel cell and a solid oxide fuel cell produced using the method.

In a cylindrical horizontal stripe-shaped solid oxide fuel cell, a fuel electrode, an electrolyte, and an air electrode are formed on a cylindrical substrate tube, and this is used as a unit power generation element. A plurality of unit power generation elements are arranged at intervals in the axial direction, and are electrically connected by an interconnector formed between the unit power generation elements.
For film formation of the fuel electrode, electrolyte, air electrode, and interconnector, for example, an apparatus in which a slurry of a constituent material is applied by screen printing as shown in Patent Document 1 is used for the advantage of manufacturing cost. ing. Thus, what was formed into a film is baked and solidified.

Japanese Patent Laid-Open No. 10-12248

By the way, in the conventional screen printing for forming a film, the screen portion of the screen plate is exposed in its entirety, and the entire periphery of the application portion is shielded. The end of each formed an upright surface substantially orthogonal to the surface of the base tube.
For this reason, for example, in the case where the film is formed between the film forming portions facing each other, such as an interconnector, a large resistance is received from the film forming portion of the unit power generating element where the slurry stands up to the bottom. This could lead to a situation in which the interconnector does not sufficiently cover the film-forming part of the unit power generation element because it was divided by the film-forming part of the unit power generation element, and the quality of the solid oxide fuel cell could be degraded. . This also has the same tendency even in the case of an electrolyte formed on the fuel electrode so as to cover it.

  Moreover, in order to ensure the thickness of the fuel electrode, the electrolyte, the air electrode, and the interconnector, it is necessary to apply the constituent material multiple times by screen printing. On the other hand, when screen printing is performed on a cylindrical surface such as a base tube, since the start end and the end of the coating portion are close to each other and face each other, a step is generated in this portion. For this reason, the next coating portion is overlapped with the step portion. However, when the start end portion and the end portion form a sharp surface substantially orthogonal to the surface of the base tube, the slurry applied on the top end There was a possibility that a gap was formed between the upper and lower coating parts that received large resistance from the part and the terminal part and did not reach the bottom part. Such gaps degrade the quality of the fuel electrode, electrolyte, air electrode and interconnector.

  In view of the above problems, an object of the present invention is to provide a high-quality solid oxide fuel cell manufacturing method and a solid oxide fuel cell using screen printing capable of smoothly stacking coated portions. .

In order to achieve the above object, the present invention provides the following means.
The method for forming a functional film according to the present invention comprises a plurality of single elements comprising a fuel electrode, an electrolyte and an air electrode on a porous substrate, and an interconnector for connecting the single elements, at least part of which is screen-printed. A method for producing a solid oxide fuel cell comprising a coating step in which a slurry of a constituent material is applied to form a film, wherein the screen printing includes at least a part of an inner edge portion of an exposed space where the screen is exposed Is performed using a screen plate in which a relaxation coating portion formed so as to sequentially reduce the exposure ratio of the screen toward the edge portion and all coating portions provided inside the relaxation coating portion. It is characterized by that.

As described above, the screen printing is performed using a screen plate formed such that at least a part of the inner edge portion of the exposed space portion where the screen is exposed gradually decreases the exposure ratio of the screen toward the edge portion. Therefore, in that portion, the amount of the slurry supplied to the coating surface through the exposed space during screen printing is gradually reduced toward the edge in the inner portion of the exposed space.
Thereby, since the thickness of the application part applied to the application surface is gradually reduced toward the end part, a smooth inclined surface can be formed. When slurry is applied so as to cover this application part, the resistance is low due to the inclined surface, so that it prevents the applied slurry from reaching the bottom or being divided by the previous application part. it can.

In addition, where the ends having smooth inclined surfaces face each other, it is possible to form a space that opens upward, in other words, a space that increases the distance between the ends facing upward. Therefore, the resistance applied to the slurry applied thereon is reduced. Thereby, since the slurry applied so that it may be piled up in this space can move smoothly below, it can control that it will not reach the bottom part, or will become the situation where it is divided by the previous application part. The inner edge portion where the exposure rate decreases sequentially is formed where it is needed.
As a result, the fuel electrode, the electrolyte, the air electrode, and the interconnector are densely formed without gaps, so that a high-quality solid oxide fuel cell with few defects due to gaps and the like can be manufactured.

The substrate may be a flat plate or a curved plate, or may be tubular with various cross-sectional shapes.
In the tubular base, the start end and the end of the application portion applied in the circumferential direction are close to each other and face each other.
In order to ensure the thickness of the fuel electrode, electrolyte, air electrode, and interconnector, it is necessary to apply the slurry of the constituent material multiple times by screen printing. It is shifted in the circumferential direction so that the parts do not overlap. For this reason, the next slurry is applied to the stepped portion in an overlapping manner. By making the starting end portion and the terminating end portion inclined, it is possible to easily enter the slurry to be applied overlappingly between them. Since the fuel electrode, the electrolyte, the air electrode, and the interconnector are densely formed without gaps, a high-quality solid oxide fuel cell with few defects due to gaps and the like can be manufactured.

  The solid oxide fuel cell according to the present invention is manufactured by using the above-described method for manufacturing a solid oxide fuel cell.

  The fuel electrode, electrolyte, air electrode, and interconnector are manufactured using a method for manufacturing a solid oxide fuel cell that is densely formed without gaps between each other. An oxide fuel cell can be obtained.

  According to the present invention, the screen printing uses a screen plate formed such that at least a part of the inner portion of the edge of the exposed space where the screen is exposed gradually decreases the exposure ratio of the screen toward the edge. As a result, the fuel electrode, the electrolyte, the air electrode, and the interconnector can be densely formed without any gap between them. Thereby, a high quality solid oxide fuel cell with few defects due to gaps and the like can be manufactured.

A solid oxide fuel cell 1 and a method for manufacturing the same according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a partial cross-sectional view schematically showing a cross section of a solid oxide fuel cell 1 manufactured using the method for manufacturing a solid oxide fuel cell 1 according to the present embodiment.
In the solid oxide fuel cell 1, a plurality of power generation elements (single elements) 5 are formed on a base tube (base body) 3 at intervals in the axial direction, and these power generation elements 5 are electrically connected in series. It is structured.

The base tube 3 is made of porous ceramic and has a hollow cylindrical shape. The fuel gas flows in the hollow portion of the base tube 3.
The power generation element 5 includes a fuel electrode 7 that is a fuel-side electrode, an air electrode 9 that is an air-side electrode, and an electrolyte 11 that is between them and passes only ions.
The air electrode 9 is formed of, for example, a lanthanum strontium-based material and generates oxygen ions from the air.

  The electrolyte 11 is made of, for example, yttria-stabilized zirconia (YSZ), and transmits oxygen ions generated at the air electrode 9 to the fuel electrode 7. The fuel electrode 7 is formed of, for example, zirconia-based ceramics such as NiO—YSZ, and generates hydrogen ions from the fuel gas. The fuel electrode 7 generates electric energy by reacting the generated hydrogen ions with oxygen ions supplied from the electrolyte.

An interconnector 13 is formed between adjacent power generation elements 5. The interconnector 13 is formed of, for example, a titanate material, and electrically connects the power generating elements 5.
The interconnector 13 is in contact with the base tube 3 and needs a function of a dense structure and an electronic conductor that can block fuel gas and air.

Hereinafter, the manufacturing process of the solid oxide fuel cell 1 will be described.
First, the base tube 3 is made into a tubular shape by extrusion molding using, for example, calcia-stabilized zirconia (CSZ) as a material. The base tube 3 is dried and moves to the next step.

Next, the fuel electrode 7, the electrolyte 11 and the interconnector 13 are started.
In this film forming process, screen printing is used. The screen printing film forming operation will be described with reference to FIGS.
A support member (not shown) supports the base tube 3 as an object so as to be rotatable and movable up and down. A squeegee 15 is provided above the base tube 3 so as to be movable upward and downward. A screen plate 17 attached to the frame 19 is movable in the lateral direction between the squeegee 15 and the base tube 3.

As shown in FIG. 2, a slurry 21 to be applied is placed on a predetermined position of the screen plate 17. From this state, the base tube 3 is raised and the squeegee 15 is lowered.
Then, with the squeegee 15 pressing the screen plate 17 against the base tube 3, the screen plate 17 moves in the horizontal direction (right direction in FIGS. 2 and 3) as shown in FIG. It rotates clockwise in FIG.
As a result, the slurry 21 is transferred onto the base tube 3 to form a film.

As shown in FIG. 4, the screen plate 17 is provided with a masking portion 23 that does not allow the slurry 21 to pass therethrough and an application pattern (exposed space portion) 25 that allows the slurry to pass therethrough.
The coating pattern 25 is formed in accordance with the shape and size of the part to be formed.
On the inner side of the edge portion 27 of the application pattern 25, a relaxation application portion (edge inner portion) 29 is provided.
The inside of the relaxation application part 29 is the entire application part 31 where the screen is completely exposed.

Next, creation of the screen plate 17 will be described.
The screen version 17 is created using the screen 33. As shown in FIG. 5, the screen 33 is knitted so that, for example, a weft yarn 35 and a warp yarn 37 of nylon yarn cross each other.
The screen 33 used for screen printing has a mesh which is the number of yarns per inch of 2.54 cm, for example, 100 to 400, and an aperture ratio of 30 to 60%. 6, the area of the space 39 formed by the adjacent weft 35 and warp 37 occupies the area of the space 41 formed at the center position of the weft 35 and the warp 37 surrounding the space 39. It is a ratio.

First, a positive as shown in FIG. 8 is printed on a film 45 that transmits light, for example. FIG. 8 shows a portion forming part A of FIG. 4 in the printing state of the film 45. In FIG. 8, the printed portion is shaded.
A portion corresponding to the entire application portion 31 is solid. The portion corresponding to the relaxation application portion 29 is printed such that the proportion of the printed portion decreases as the proportion of the printed portion increases from the portion corresponding to the entire application portion 31. The portion corresponding to the masking portion 23 is not printed.

  FIG. 8 illustrates the state of printing of the portion corresponding to the relaxation application portion 29, that is, the state in which the proportion of the print portion gradually decreases from the portion corresponding to the entire application portion 31 toward the masking portion 23. However, the present invention is not limited to this. For example, the portion corresponding to the relaxation application portion 29 may be printed such that the number of dot-printing portions having substantially the same area per unit area is sequentially reduced as shown in FIG. In addition, it is good also as a form suitably.

For example, a diazo photosensitive emulsion 43 is coated on the surface of the screen 33 and dried.
As shown in FIG. 7, the printed film 45 is superimposed on the photosensitive emulsion 43 side of the screen 33.
Note that printing may be performed directly on the photosensitive emulsion 43 without using the printed film 45.
The ultraviolet lamp 47 irradiates (exposes) ultraviolet rays from the film 45 side for a predetermined time. Thereafter, the film 45 is removed and water is applied to the photosensitive emulsion 43 to stop (develop) the exposure.
As a result, as shown in FIG. 9, the unprinted portion becomes a film 49 in which the photosensitive emulsion 43 that has been exposed and cured is fixed to the screen 33 and does not pass through the slurry 21. On the other hand, the photosensitive emulsion 43 flows with water in the non-photosensitive printed portion, and the screen 33 through which ink passes is exposed.

That is, the screen 33 is exposed to 100% in the portion corresponding to the entire coating portion 31, and the portion corresponding to the masking portion 23 is covered with the 100% film 49, and the exposure of the screen 33 is 0%.
A film 49 is partially formed in a portion corresponding to the relaxation application portion 29. Further, the exposure ratio at which the screen 33 without the film 49 is exposed gradually decreases from the portion corresponding to the entire coating portion 31 toward the portion corresponding to the masking portion 23, that is, the edge portion 27.

In this way, the screen plate 17 for the fuel electrode 7, the electrolyte 11, and the interconnector 13 is manufactured. The fuel electrode 7, the electrolyte 11, and the interconnector 13 are formed using the screen plates 17.
In the fuel electrode 7, for example, a predetermined amount of each powder of nickel oxide and yttria stabilized zirconia is mixed, and a solvent is added to form a slurry 21.
The slurry 21 is attached so as to cover the coating pattern 25 of the screen plate 17, and screen printing is performed as described above. Screen printing is repeated several times to obtain the required thickness.

Next, the electrolyte 11 is deposited so as to cover the fuel electrode 7 by screen printing a plurality of times. In the case of the electrolyte 11, a predetermined amount of each powder of yttria-stabilized zirconia is mixed, and a solvent is added to form a slurry 21.
Next, the interconnector 13 is formed between the electrolyte 11 of the adjacent power generation element 5 and the fuel electrode 7 by screen printing a plurality of times. In the case of the interconnector 13, a predetermined amount of titanate powder is mixed and a solvent 21 is added to form a slurry 21.

In this way, when the fuel electrode 7, the electrolyte 11, and the interconnector 13 are formed, firing is performed using an electric furnace.
Next, the screen plate 17 for the air electrode 9 is manufactured, and the air electrode 9 is formed so as to cover the electrolyte 11 and the interconnector 13 by screen printing a plurality of times. In the air electrode 9, a predetermined amount of lanthanum strontium powder is mixed, and a solvent is added to form a slurry 21.
When film formation of the air electrode 9 is completed, it is baked using an electric furnace.

  Next, actions and effects according to the present embodiment will be described with reference to FIGS. 11 and 12 show a partial cross section along the axial direction of the base tube 3, and FIG. 11 shows a state when screen printing is performed according to the present embodiment. FIG. 12 shows a state of conventional screen printing.

The conventional coating pattern 25 is composed of a part where the screen 33 is completely exposed and a part around which the screen 33 is shielded, that is, a part where the screen 33 is not exposed at all. When screen printing is performed using this, as shown in FIG. 12, the end portion of the film forming portion 51 applied to the base tube 3 forms a vertical surface 53 that is substantially perpendicular to the surface of the base tube 3.
The second film forming part 55 (for example, the interconnector 13) formed between the film forming parts 51 receives a large resistance from the corner formed by the upper surface and the vertical surface 53 of the film forming part 51. The substrate tube 3 was not reached (FIG. 12B), or it was divided by the film forming portion 51 and part of the film forming portion 51 was not covered (FIG. 12A).

When screen printing is performed using the screen plate 17 in which the relaxation application portion 29 is provided in the coating pattern 25 as in the present embodiment, the exposure ratio at which the screen 33 is exposed in the relaxation application portion 29 is set toward the edge 27. Since it is formed so as to decrease sequentially, the amount of the slurry 21 supplied to the base tube 3, that is, the coating surface through the exposed space of the screen plate 17 during screen printing is directed toward the edge 27 in the relaxation coating unit 29. It will decrease sequentially.
Thereby, since the film-forming part 51 apply | coated on the base | substrate pipe | tube 3 becomes thin toward the edge part, the thickness near the edge part becomes small sequentially, Therefore The smooth inclined surface 57 can be formed.
Since the second film forming part 55 formed between the film forming parts 51 receives less resistance due to the inclined surface 57 when the slurry 21 is pushed in during screen printing, the applied slurry 21 is less than the substrate tube 3. It can be suppressed that the situation does not reach or is divided by the film forming portion 51.

As shown in FIG. 13, since the base tube 3 is a cylinder, the start end portion 61 and the end end portion 63 of the film forming portion 59 applied in the circumferential direction are close to each other and face each other. For this reason, a step is generated between the start end portion 61 and the end end portion 63.
On the other hand, in order to ensure the thickness of the fuel electrode 7, the electrolyte 11, the air electrode 9, and the interconnector 13, it is necessary to apply the slurry 21 a plurality of times by screen printing. Since these need to be continuously formed in the circumferential direction, they are shifted in the circumferential direction so that the step portions do not overlap.
For this reason, the next slurry 21 is applied on the stepped portion, but in this embodiment, since the relaxation applying portion 29 is provided as described above, the start end portion 61 and the end end portion 63 are gradually formed. It becomes thinner. As a result, the start end portion 61 and the end end portion 63 are largely opened with a large inclination, so that the slurry 21 of the second film forming portion 65 to be applied in an overlapping manner can easily enter.
Therefore, since the second film forming portion 65 is formed so as to reach the base tube 3, the fuel electrode 7, the electrolyte 11, the interconnector 13, and the air electrode 9 are densely formed without any gaps, and performance deterioration due to the gaps or the like. Therefore, it is possible to manufacture a high-performance solid oxide fuel cell 1 with a small amount of.

  Further, in this embodiment, since the starting end 61 and the terminating end 63 of the film forming portion 59 can be gradually made thinner toward the front, by adjusting the thickness, for example, as shown in FIG. It is also possible to eliminate the step by making 61 and the terminal portion 63 overlap.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, the present embodiment is a solid oxide fuel cell 1 using a cylindrical substrate tube 3, but is not limited to this, for example, a solid oxide fuel cell using a flat plate substrate. 1 may be applied.

It is a fragmentary sectional view showing roughly the section of the solid oxide fuel cell manufactured using the manufacturing method of the solid oxide fuel cell concerning one embodiment of the present invention. It is a schematic diagram which shows the structure of the screen printing concerning one Embodiment of this invention. It is a schematic diagram which shows the structure of the screen printing concerning one Embodiment of this invention. It is a fragmentary top view which shows the screen plate concerning one Embodiment of this invention. It is a fragmentary top view which shows the screen concerning one Embodiment of this invention. FIG. 6 is an enlarged partial plan view showing a part of FIG. 5 in an enlarged manner. It is a schematic diagram which shows the manufacturing process of the screen plate concerning one Embodiment of this invention. It is a fragmentary top view which shows the printed film concerning one Embodiment of this invention. It is an enlarged plan view which shows the A section of FIG. It is a fragmentary top view which shows another aspect of the printed film concerning one Embodiment of this invention. It is the longitudinal cross-sectional view typically shown explaining the effect | action of the screen printing concerning one Embodiment of this invention. It is the longitudinal cross-sectional view typically shown explaining the effect | action of the conventional screen printing. It is the cross-sectional view typically shown explaining the effect | action of the screen printing concerning one Embodiment of this invention. It is the cross-sectional view typically shown showing another aspect of the screen printing concerning one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid oxide fuel cell 3 Base tube 5 Power generation element 7 Fuel electrode 9 Air electrode 11 Electrolyte 13 Interconnector 17 Screen plate 25 Application pattern 27 Edge 29 Relaxation application part 33 Screen

Claims (3)

A plurality of single elements composed of a fuel electrode, an electrolyte, and an air electrode and an interconnector connecting the single elements are formed on a porous substrate by coating a slurry of a constituent material by screen printing at least partially. A manufacturing method of a solid oxide fuel cell having a coating step,
The screen printing includes a relaxation application part formed such that at least a part of an inner part of an edge part of an exposed space part where the screen is exposed gradually reduces the exposure ratio of the screen toward the edge part, and the relaxation application part A method for producing a solid oxide fuel cell, characterized in that the method is carried out using a screen plate in which all the coating portions provided inside are formed .   2. The method for manufacturing a solid oxide fuel cell according to claim 1, wherein the base is tubular.   A solid oxide fuel cell manufactured using the method for manufacturing a solid oxide fuel cell according to claim 1.

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