JP2002025573A - Manufacturing method of electrode for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a quality electrode for fuel cell economically. SOLUTION: A 1st electrode mold 10 (positive electrode mold) is manufactured by photo-forming, a 2nd electrode mold 20 (negative electrode mold) is manufactured by electric casting using the 1st electrode mold 10, a 3rd electrode mold (positive electrode mold) is manufactured by using the 2nd electrode mold 20, and the electrodes for fuel cells are economically manufactured by electric casting using the 3rd electrode mold.

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 an electrode for a fuel cell, and more particularly, to a method for manufacturing a first electrode type by photoforming and then forming the second electrode type and a third electrode type by electroforming.
The present invention relates to a method for sequentially manufacturing an electrode type and manufacturing a high-quality fuel cell electrode using the third electrode type.

[0002]

2. Description of the Related Art Conventionally, in photoforming which combines a photoresist pattern forming technique and an electroforming technique, an electrode for electroplating is formed in an electrode form, and a metal layer is formed on the electrode form by electroplating. This is a technique for producing various metal sheet bodies having a thickness of several tens to several hundreds of micrometers by attaching the metal layer and peeling the metal layer. This photoforming has been widely used in the past, and according to this photoforming, since the adder cut does not occur unlike the photoetching, it is possible to form finer concaves and concaves of various shapes, irregularities, and fine holes. It can be carried out. For example, conventionally, various chemical vapor deposition masks, outer blades of electric razors, fine screens, fine meshes, fine filters, and the like have been manufactured by photoforming technology.

On the other hand, recently, automakers are keenly developing elemental technologies for the practical use of automobile fuel cells. For example, in a fuel cell using hydrogen and oxygen as fuel, a potassium hydroxide solution is used as an electrolytic solution, O ₂ gas as a positive electrode active material is supplied to the surface of the positive electrode, and H ₂ as a negative electrode active material is supplied to the surface of the negative electrode. ₂ gas supplies, via current and electrolyte solution which occurs between the positive electrode and the negative electrode, to generate electricity by reacting H ₂ gas and O ₂ gas. As this type of fuel cell electrode, for example, a thin metal plate of nickel is applied, and an electrochemical reaction occurs between an active material such as H ₂ or O ₂ , an electrolytic solution, and a solid electrode on the surface of the electrode. Therefore, in order to promote the contact between the electrode and the active material, a large number of fine concave portions having a diameter of about 1 mm are formed in the electrode at a fine pitch (about 1 to 2 mm) in the vertical and horizontal directions.

[0004]

When a large number of recesses and irregularities are formed in a thin metal plate such as the fuel cell electrode,
Usually, it is formed by press molding. However, about 1mm in diameter
Although it is possible to manufacture a metal mold having a large number of minute concave portions, the manufacturing cost of the metal mold is extremely high, which is not practical. Therefore, it is conceivable to manufacture a fuel cell electrode by photoforming. However, if the electrode mold is manufactured by photoforming, and the electrode for the fuel cell is simply formed by electroforming using the electrode mold, the corners of the minute recesses are too sharp, and the burr-like minute projections are likely to occur. When manufacturing a large fuel cell electrode, there is a problem that it is difficult to release the electrode smoothly when releasing the electrode, and defects such as minute cracks are likely to occur. An object of the present invention is to provide a method for manufacturing a fuel cell electrode that can solve the above-mentioned problems.

[0005]

According to a first aspect of the present invention, there is provided a method of manufacturing an electrode for a fuel cell, comprising forming a large number of fine concave portions on a thin metal sheet. A first step of manufacturing a conductive first electrode mold by electroforming a metal on the surface of the first electrode mold by electroforming, and then peeling the sheet to form a sheet having the same structure as the fuel cell electrode. Of the second electrode type
And a third step of electrodepositing a metal on the surface of the mold of the second electrode mold by electroforming and then peeling to produce a sheet-shaped third electrode mold having a large number of minute recesses. A fourth step of producing a sheet-shaped fuel cell electrode by electrodepositing a metal on the surface of the third electrode by electroforming and then peeling the metal.

In a first step, a conductive first electrode type is manufactured by photoforming. In this case, a metal base plate or a non-metal base plate having a conductive film formed on the surface is used, for example, a positive photoresist is applied to the base plate, and a mask is formed by forming a predetermined pattern on the photoresist. By exposing with the originals stacked,
The base member is immersed in a predetermined electroplating bath (for example, a nickel sulfate plating bath) while removing the photoresist other than the predetermined pattern of the photoresist and leaving the predetermined pattern of the photoresist. When the base plate is used as a cathode and the base plate is subjected to electroforming to electrodeposit a metal and then exposed, and then all the photoresist is removed, a first electrode type is obtained.

Next, in a second step, a predetermined release agent (for example, bengara) is applied to the surface of the mold of the first electrode type, and then is immersed in an electroplating bath similar to the above, to form a nickel-made material. A sheet having a structure similar to that of a fuel cell electrode, in which a metal (for example, nickel) is electrodeposited on the surface of the first electrode type by electroforming with the anode being used as a cathode while the first electrode type is used as a cathode. A second electrode mold having a shape of is formed.

Next, in a third step, an insulating film is formed on the surface opposite to the mold surface of the second electrode type, and a predetermined release agent similar to the above is applied to the mold surface of the second electrode type. In the state of application, the second
In a state where the electrode mold is immersed in the same electroplating bath as described above, a metal (for example, nickel) is electrodeposited by electroforming on the mold surface of the second electrode mold and then peeled off to form a sheet-like sheet having a number of minute recesses. A three-electrode type is manufactured.

Next, in a fourth step, an insulating film is formed on the surface opposite to the surface of the mold of the third electrode type, and a predetermined release agent similar to the above is applied to the surface of the mold of the second electrode type. In the state of application, the third
In a state where the electrode mold is immersed in the same electroplating bath as described above, a metal (for example, nickel) is electrodeposited by electroforming on the mold surface of the third electrode mold and then peeled off to produce a sheet-shaped fuel cell electrode. .

[0010]

Embodiments of the present invention will be described below with reference to the drawings. First, the structure of an electrode for a fuel cell of an automobile will be described. An electrode for a fuel cell of an automobile (hereinafter, referred to as a battery electrode) is applied to a positive electrode or a negative electrode of a fuel cell, and in the present embodiment, is made of nickel.

As shown in FIG. 1 to FIG.
Is a rectangular sheet of A4 size, for example.
The thickness t is, for example, 200 to 300 μm, and a large number of minute concave portions 2 (outer diameter d = approximately 1.0 mm, depth h = 0.4 to 0.2 μm).
8 mm) is a small pitch a (for example, a = 1.
5 to 2.5 mm).
However, the minute concave portion 2 is not always formed on the entire surface, and may be formed to have a predetermined pattern.

Next, a method for manufacturing the battery electrode will be described. First Step (Production of First Electrode Type): As shown in FIG. 4, a positive original plate 4 in which a portion corresponding to the minute concave portion 2 is made a black circle 3 and other portions are made transparent using a transparent glass plate. . The diameter of the black circle 3 in the positive master 4 is equal to the outer diameter d of the minute concave portion 2 in FIG. 3, and the vertical and horizontal pitch of the black circle 3 is equal to the pitch a of the minute concave portion 2.

Next, as shown in FIGS. 5 to 8, a conductive first electrode mold 10 is manufactured by photoforming.
In this case, first, as shown in FIG. 5, a photoresist layer 12 made of a positive photoresist having an appropriate thickness is formed on the upper surface of a base plate 11 made of A4 size metal (for example, phosphor bronze or stainless steel). At the same time as forming, the positive master 4 is superimposed on the upper surface of the photoresist layer 12, and is exposed by irradiating ultraviolet rays or excimer laser from above. As a result of this exposure, the photoresist layer 12 other than the portions corresponding to the black circles 3 is destroyed. Therefore, when the photoresist layer 12 is washed with a hydrofluoric acid solution or the like having an appropriate concentration, the pattern corresponding to the positive master 4 is developed as shown in FIG. can do.

Next, as shown in FIG.
The base plate 11 having the same photoresist pattern as described above is immersed in a nickel plating bath, and nickel plating is applied as electroforming until the thickness becomes equal to that of the photoresist layer 12. In this case, as a plating solution for the nickel plating bath, for example, a solution containing a nickel sulfate solution as a main component is applied, and a plating process (electroforming) is performed using the base plate 11 as a cathode and a nickel anode. By this plating process, nickel of the anode is electrodeposited on the pace plate 11 of the cathode.

Thereafter, the base plate 11 is taken out of the nickel plating bath and dried, and then the upper surface of the base plate 11 is irradiated with an ultraviolet ray or an excimer laser to destroy the photoresist layer 12a corresponding to the matrix-shaped black circle 3. Thereafter, by washing with an appropriate washing liquid, the first electrode type 10 as shown in FIG. 8 is obtained. The first electrode type 10 can be called a positive electrode type.

Second step (production of second electrode type):
In the step, nickel is electrodeposited on the mold surface of the first electrode mold 10 and then peeled off to form a sheet-like second electrode mold 20 having a large number of minute recesses, which is the same as the fuel cell electrode mold 1. A second electrode mold 20 having a structure is manufactured.

In this case, first, an appropriate release agent (for example, bengara) is applied in a thin film shape on the mold surface of the first electrode mold 10, and then the first electrode mold 10 is placed in a nickel plating bath similar to the above. Immersion, using the same plating solution and nickel anode as described above, and plating (electroforming) for a sufficient time using the first electrode mold 10 as a cathode to form a surface of about 200 to 300 μm on the mold surface of the first electrode mold 10. Electrodeposited layer 20a of nickel
To form

Thereafter, the first electrode mold 10 is taken out of the nickel plating bath, and the electrodeposition layer 20a is peeled off. Then, the sheet-like second electrode mold 20 having the same structure as the fuel cell electrode 1 and having a large number of minute recesses is obtained. can get. In addition, the second electrode type 2
0 corresponds to a negative electrode type, and since the lower surface side of the second electrode type 20 is a mold surface, as shown in FIG. Form an insulating film 21 made of a synthetic resin material.

Third step (production of third electrode type): This third step
In the step, nickel is electrodeposited on the mold surface of the second electrode mold 20 and then peeled off to form a third sheet-like sheet having a number of minute recesses.
Fabricate an electrode mold. In this case, first, the same mold release agent as described above is applied to the mold surface on the lower surface side of the second electrode mold 20, and then the second electrode mold 20 is immersed in the same nickel plating bath as above, and the same as above. Using a plating solution and a nickel anode,
Plating (electroforming) for a sufficient time using the second electrode type 20 as a cathode, as shown in FIG.
An electrodeposition layer 30a of nickel having a thickness of about 300 to 400 μm is formed on the surface of the mold 0.

Thereafter, the second electrode type 20 is taken out from the nickel plating bath, and the electrodeposition layer 30a is peeled off.
As shown in FIG. 2, a sheet-shaped third electrode mold 30 having a large number of minute concave portions is obtained. Note that the third electrode type 30 is a positive electrode type, and since the upper surface of the third electrode type 30 is a mold surface, as shown in FIG. An insulating film 31 made of a synthetic resin material is formed on the lower surface opposite to the surface.

Fourth step (manufacture of fuel cell electrode): In this fourth step, nickel is electrodeposited on the surface of the third electrode mold 30 and then peeled off to manufacture a sheet-like fuel cell electrode 1. . In this case, first, the same release agent as described above is applied to the mold surface of the third electrode mold 30, and then the third electrode mold 30 is immersed in the same nickel plating bath as above, and the same plating solution as above is applied. Using a nickel anode, plating (electroforming) for a sufficient time using the third electrode mold 30 as a cathode,
As shown in FIG. 13, about 20
An electrodeposition layer 1a of nickel having a thickness of 0 to 300 μm is formed.

Thereafter, the third electrode mold 30 is taken out of the nickel plating bath, and the electrodeposition layer 1a is peeled off.
Thus, a sheet-like fuel cell electrode 1 having a large number of minute concave portions as shown in FIG.

According to the above-described method for manufacturing a battery electrode, the conductive first electrode type 10 is formed by photoforming.
Then, nickel is electrodeposited by electroforming using the first electrode mold 10 to produce a second electrode mold 20, and then nickel is electroformed by electroforming using the second electrode mold 20. Then, the third electrode mold 30 is manufactured, and then nickel is electrodeposited by electroforming using the third electrode mold 30 to manufacture the fuel cell electrode. Therefore, the corners of the minute concave portions become too sharp. There is no burr-like microprojection, and even if the fuel cell electrode 1 is relatively large, the fuel cell electrode 1 is easily released smoothly when the fuel cell electrode 1 is released. Defects such as cracks are less likely to occur, and high-quality fuel cell electrodes can be economically mass-produced.

Next, a modified example in which the above-described embodiment is partially changed will be described. The base plate 1 is not necessarily made of metal, and may be a non-metallic base plate having a surface on which a conductive film is formed. Further, in the above-described embodiment, the case where the fuel cell electrode 1 made of nickel is manufactured is described as an example. However, the electrode 1 for fuel cell is not limited to nickel, and may be made of aluminum, chromium, or copper. Good. In this case, in the fourth step, the electroforming may be performed using an appropriate plating solution and using any anode such as aluminum, chromium, or copper. In addition, it goes without saying that the present embodiment can be implemented in a form in which various changes are added to the embodiment without departing from the spirit of the present invention.

[0025]

According to the method for manufacturing an electrode for a fuel cell of the first aspect, a conductive first electrode type (corresponding to a positive electrode type) is manufactured by photoforming, and then the first electrode type is used. A metal is electrodeposited by electroforming to produce a second electrode type (corresponding to a negative electrode type), and then a metal is electrodeposited by electroforming using the second electrode type to form a third electrode type (positive electrode type). Electrode type), and then, using the third electrode type, a metal is electrodeposited by electroforming to manufacture an electrode for a fuel cell. There is no burr-like microprojection, and even for relatively large fuel cell electrodes, it is easy to release smoothly when releasing the electrode, and defects such as minute cracks are unlikely to occur High-quality fuel cell electrodes can be mass-produced economically. Swell.

[Brief description of the drawings]

FIG. 1 is a plan view of a fuel cell electrode according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of a fuel cell electrode.

FIG. 3 is an enlarged sectional view of a main part of a fuel cell electrode.

FIG. 4 is an enlarged plan view of a main part of a positive master.

FIG. 5 is an enlarged sectional view of an essential part of a base plate, a photoresist layer, and a positive master.

FIG. 6 is an enlarged sectional view of a main part of a base plate and a photoresist layer.

FIG. 7 is an enlarged sectional view of a main part of a base plate, a photoresist layer, and an electrodeposition layer.

FIG. 8 is an enlarged sectional view of a main part of a first electrode type.

FIG. 9 is an enlarged sectional view of a main part of a first electrode type and an electrodeposition layer.

FIG. 10 is an enlarged sectional view of a main part of a second electrode type.

FIG. 11 is an enlarged sectional view of a main part of a second electrode type and an electrodeposition layer.

FIG. 12 is an enlarged sectional view of a main part of a third electrode type.

FIG. 13 is an enlarged sectional view of a main part of a third electrode type and an electrodeposition layer.

FIG. 14 is an enlarged sectional view of a main part of a fuel cell electrode separated from a third electrode type.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrode for fuel cells 2 Micro recess 10 First electrode type 20 Second electrode type 30 Third electrode type

Claims (1)

[Claims] 1. A method for forming an electrode for a fuel cell, wherein a large number of fine concave portions are formed in a thin metal sheet, comprising: a first step of producing a conductive first electrode type by photoforming; Next, a metal is electrodeposited by electroforming on the mold surface of the first electrode mold and then peeled off to produce a sheet-like second electrode mold having the same structure as the fuel cell electrode. A third step in which a metal is electrodeposited on the surface of the two-electrode mold by electroforming and then peeled to produce a sheet-shaped third electrode mold having a large number of minute recesses; A metal is electrodeposited by electroforming and then peeled off to produce a sheet-like fuel cell electrode.
A process for producing an electrode for a fuel cell, comprising the steps of: