JPH09283155A - Manufacture of electrode for high molecular solid electrolyte fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode, which can improve the H2 gas supplying property of an anode and which can improve the oxidizing gas and water discharging property of a cathode, by forming specified grooves in an electrode base material, and forming a catalyst layer thereon in the predetermined condition. SOLUTION: An electrode base material 1, which is desirably formed of a carbon paper, is formed with plural parallel grooves or grid-shaped grooves 3 at 1μ-1mm of width by a dicing device, and the paste-like catalyst obtained by forming the carbon powder, which carries platinum, into the paste with water or the organic solvent such as alcohol having C3-4 is coated thereon, and dried so as to form a catalyst layer. As a cross section shape, a square at about 1μ-1mm of width and at about 1μ-1mm of depth is desirable, but various shapes such as a U-shape, V-shape and semi-circular are possible.

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 polymer electrolyte fuel cell, and more particularly to a method for manufacturing an electrode suitable for improving the characteristics of a polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art Conventionally, in order to manufacture an electrode for a polymer electrolyte fuel cell, a paste catalyst is applied to one side of an electrode base material cut out in accordance with the shape of the electrode such as carbon paper and dried. The catalyst layer was formed.

On the other hand, in recent years, solid polymer electrolyte fuel cells have been required to be lighter and smaller, so that the electrodes used therefor are also required to be smaller, and the catalyst utilization rate is improved and the anode (H ₂ electrode) is used. ) Has been required to be improved, and the discharge property of water as a cathode (O ₂ electrode) has been required to be improved.

However, in the above-mentioned conventional electrode manufacturing method,
It has not been possible to obtain an electrode that can meet such requirements.

[0005]

Therefore, the present invention is directed to improving the utilization rate of the catalyst, improving the supply of hydrogen gas as the anode (H ₂ electrode), and supplying the oxidizing gas as the cathode (O ₂ electrode). Another object of the present invention is to provide a method for producing an electrode for a polymer electrolyte fuel cell, which can improve the drainage of water.

[0006]

Means for Solving the Problems In order to solve the above problems, a method for producing an electrode for a polymer electrolyte fuel cell according to the present invention comprises forming a plurality of parallel grooves or grid-like grooves on an electrode substrate, It is characterized in that a catalyst in paste form is applied thereon and dried to form a catalyst layer, and the groove is formed by using a dicing device, and its width is 1 μm to 1 mm. desirable. The above-mentioned electrode base material is preferably carbon paper, and the paste-like catalyst is preferably one in which carbon powder carrying platinum is made into a paste form with water or an organic solvent.

The groove formed on the surface of the electrode base material maximizes the amount of the catalyst which is carried and exposed on the surface of the electrode base material and utilized in the electrode reaction as described above, and the gas supply to the electrode and It has a function for smoothing gas discharge from the electrode. Therefore, the width, pitch, depth, etc. of the grooves may be appropriately determined within a range that does not impair the function. A preferred cross-sectional shape of the groove is a rectangular shape having a width of about 1 μm to 1 mm and a depth of about 1 μm to 1 mm, and its pitch is about 5 μm to 5 mm, and the number of grooves is determined according to the pitch and the width of the electrode base material. It However, the cross-sectional shape of the groove is not particularly limited to the rectangular shape as long as the functions of increasing the electrode area and smooth flow of gas are secured, and various shapes such as U-shape, V-shape, and semi-circle shape can be used. can do.

It is not desirable that the plurality of grooves form a curved line or that adjacent grooves intersect with each other from the viewpoint of smooth gas supply and smooth discharge, and the linear grooves are located in parallel with each other. It is preferable that the plurality of parallel linear grooves of (1) intersect at a right angle to form a lattice shape. Although it is not easy to form a plurality of grooves on the surface of the electrode base material such as the carbon paper described above, the present invention can be suitably formed using a dicing device. Two or more parallel blades are usually installed in this dicing device, and a plurality of parallel or lattice-shaped grooves can be formed on the surface of the electrode base material by rotating the blades. However, in the method of the present invention, a plurality of grooves can be formed by means other than this dicing device.

Next, the surface of the electrode substrate having the plurality of grooves thus formed is coated with a catalyst layer. By forming this catalyst layer on the entire surface of the electrode base material including the groove, one of the purposes of the method of the present invention of increasing the electrode area is achieved. This catalyst is formed by supporting a catalyst metal on a fine particle carrier, preferably carbon particles as the carrier, and platinum group metals such as platinum and palladium as the catalyst metal. Even if the catalyst is coated on the surface of the electrode base material as it is, the carrier such as carbon particles cannot be firmly adhered to the surface of the electrode base material such as carbon paper, and therefore the carrier is an organic solvent having an appropriate viscosity, for example, A paste is prepared by using an alcohol having 3 to 4 carbon atoms, the paste is applied to the surface of the electrode base material, dried, and further fired if necessary to form a fuel cell electrode. Since the electrode is formed by applying a paste onto an electrode base material having a plurality of grooves and drying the paste, the paste enters the grooves, that is, the recesses on the surface of the electrode base material, and the amount of the paste above the grooves is insufficient, so that the final As a result, irregularities are generated on the surface of the electrode, which increases the electrode area and improves the catalyst utilization rate.

In the polymer solid oxide fuel cell electrode manufactured by the above manufacturing method, a plurality of parallel grooves or grid grooves, preferably a plurality of grooves, are formed on the electrode substrate, and the catalyst layer is formed thereon. Therefore, the electrode area is remarkably increased, and when the electrode is used for the polymer electrolyte fuel cell, the joint area with the electrolyte membrane is increased several times. Therefore,
Using this electrode at the anode (H _2-pole) side, to improve the supply of hydrogen gas along with contact efficiency therefore catalyst utilization of hydrogen gas is increased, the cathode (O _2-pole) when used in the side, oxygen The efficiency of contact with gas and thus the utilization rate of the catalyst is improved, the supply of the oxidizing gas and the discharge of the produced water are improved, and the cell characteristics of the polymer electrolyte fuel cell are improved.

[0011]

Embodiments of the method of the present invention will now be described with reference to the accompanying drawings.

Example 1 As shown in FIG. 1, the electrode base material is 150 mm in length.
× width 200mm × thickness 0.36mm carbon paper 1 by rotating the blade 2 of the dicing device, width 100μm depth 50
Grooves of μm are formed in a grid pattern at a pitch of 200 μm as shown in FIG. 2, and carbon powder (particle size 20 μm to 30 μm) carrying platinum is placed on the grid-shaped grooves 3 with an organic solvent (1-propanol). The catalyst in paste form was applied and dried to form a catalyst layer 4 having a thickness of 50 to 80 μm as shown in FIG. 3 to obtain a polymer solid oxide fuel cell electrode 5.

The polymer solid oxide fuel cell electrode 5 thus obtained is joined to the central portion of separators 6 and 7 of length 250 mm × width 250 mm × thickness 8 mm as shown in FIG. The electrolyte membrane (Nafion 112 membrane manufactured by DuPont) 8 was sandwiched and opposed to each other to form a single cell 9 of a polymer electrolyte fuel cell. In this single cell 9, the fuel gas is H ₂ , the oxidizing gas is air, and 1 kgf / cm
^When operated at a pressure of ² , the maximum output of the single cell 9 having the separators 6 and 7 equipped with the electrode 5 of the present example is 0.4.
At W / cm ² , the output was improved as compared with the comparative example described later. This means that the electrode 5 of the present embodiment has an increased bonding area with the electrolyte membrane 8, an improved utilization rate of the catalyst, an improved hydrogen gas supply ability as an anode, an air supply ability as a cathode, and generated water. It is presumed that this is because the discharge property was improved and the battery characteristics were improved as a whole.

[0013]

Comparative Example 1 On the other hand, a solid polymer electrolyte fuel cell electrode 5'shown in FIG. 4 having the same dimensions as in Example 1 in which the catalyst layer 4 was formed on the carbon paper 1 on which the grid-shaped grooves 3 were not formed was used. A single cell 9'of a polymer electrolyte fuel cell was constructed in the same manner as above. This single cell 9 '
Output under the same conditions as in Example 1
It was 0.3 W / cm ² , and the output decreased.

[0014]

As can be seen from the above description, according to the method for producing an electrode for a polymer electrolyte fuel cell of the present invention, a plurality of parallel grooves or grid-like grooves formed on the surface of an electrode substrate are The surface area of the catalyst layer formed on the surface of the electrode base material is increased to improve the utilization rate of the catalyst, and the hydrogen gas is supplied more easily as the anode (H ₂ electrode) and the oxidizing gas is used as the cathode (O ₂ electrode). It is possible to provide an electrode for a polymer electrolyte fuel cell with improved battery characteristics and improved battery characteristics.

[Brief description of drawings]

FIG. 1 is a schematic view showing a state in which a groove is formed on a carbon paper as an electrode base material by a dicing device.

FIG. 2 is a plan view showing a state in which grid-like grooves are formed on carbon paper.

3 is a cross-sectional view showing an electrode for a polymer electrolyte fuel cell of an example obtained by forming a catalyst layer on the groove of the carbon paper of FIG.

FIG. 4 is a cross-sectional view showing a conventional polymer solid oxide fuel cell electrode.

FIG. 5 is a cross-sectional view showing a single cell of a polymer electrolyte fuel cell.

[Explanation of symbols]

 1 Electrode Base Material (Carbon Paper) 2 Blade of Dicing Device 3 Lattice-Shaped Grooves 4 Catalyst Layer 5 Polymer Solid Electrolyte Fuel Cell Electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 391016716 STONEHART ASSOCIATES INCORPORATED United States 06443 Connecticut, Madison, Cottage Road 17, P-O Box 1220 (72) Inventor Keiji Murayama Kanagawa 2-7 Shinmachi, Hiratsuka-shi, Japan Tanaka Kikinzoku Kogyo Co., Ltd. Technology Development Center

Claims (4)

[Claims] 1. A polymer solid characterized in that a plurality of parallel grooves or a grid-like groove is formed on an electrode base material, a paste-like catalyst is applied onto the groove, and the catalyst layer is dried to form a catalyst layer. Manufacturing method of electrode for electrolyte fuel cell. 2. The electrode substrate is 1 μm by a dicing device.
The method for producing an electrode for a polymer electrolyte fuel cell according to claim 1, wherein a plurality of parallel grooves or a grid-shaped groove having a width of m to 1 mm are formed. 3. The method for producing an electrode for a polymer electrolyte fuel cell according to claim 1, wherein the electrode base material is carbon paper. 4. A method for producing an electrode for a polymer electrolyte fuel cell, wherein the paste-like catalyst is carbon powder carrying platinum and made into a paste with water or an organic solvent.