JPH05311475A - Gas diffusion electrode and its production - Google Patents

Abstract

PURPOSE:To easily obtain the large-sized gas diffusion electrode which has high strength, is hardly deflectable and is easy to use by pouring the dispersion of the raw materials of a reaction layer and/or a gas diffusion layer into the stitch structure of a foamed metal, then removing a surfactant and press molding the metal. CONSTITUTION:The dispersion of the raw materials of the gas diffusion layer and/or the dispersion of the raw materials of the reaction layer are poured and filled into the stitch structure of the foamed metal 1. The dispersion of the raw materials of the reaction layer consists of, for example, hydrophilic and water repellent carbon black and polytetrafluoroethylene, surfactant and water. The above-mentioned dispersion of the raw materials of the gas diffusion layer consists of, for example, the water repellent carbon black and polytetrafluoroethylene, surfactant and water. After the poured raw materials are dried, the surfactant is extracted away. The reaction layer 8 where the fine hydrophilic parts 6 and the water repellent parts 7 allowing the admission and emission of gases nest and coexist. and the gas diffusion layer 10 where the water repellent parts 9 disperse are formed in two layers into the said stitch structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas diffusion electrode used in electrolysis, fuel cells, electroplating, electrochemical reactors and the like, and a method for producing the same.

[0002]

2. Description of the Related Art A conventional gas diffusion electrode has a reaction layer in which a fine hydrophilic portion (passage) through which a liquid can permeate and a fine water repellent portion (passage) through which a gas can flow in and out are mixed and in contact with each other. Generally, it is attached to a current collector, or the reaction layer and a gas diffusion layer in which fine water-repellent portions (passages) capable of gas flow are finely dispersed are attached to a current collector. These gas diffusion electrodes are manufactured by dispersing the reaction layer raw material and the gas diffusion layer raw material in an aqueous solution, filtering and drying them, forming them into dough with solvent naphtha, and then collecting them into a plate with rolls. It is a method of obtaining a gas diffusion electrode by putting it in a metal jig together with the metal net of the body and hot pressing with the jig.

By the way, in this method for manufacturing a gas diffusion electrode, the steps are complicated, the workability is poor, and mass production is not possible. Further, since a jig is used, it is difficult to increase the size, and since it cannot be continuously manufactured by hot pressing, the productivity is low. Further, the gas diffusion electrode obtained by the above manufacturing method has low strength, is easily bent, and is inconvenient to handle and cannot be increased in size. Poor efficiency and insufficient electrode performance.

[0004]

Therefore, the present invention is to provide a gas diffusion electrode which has high strength, is hard to bend, is easy to handle, can be made large, and has good current collecting efficiency and excellent electrode performance. It is what Further, it is an object of the present invention to provide a method capable of efficiently manufacturing such a gas diffusion electrode in a simple process with good workability and suitable for mass production, and without using an expensive jig or hot press. It is a thing.

[0005]

The gas diffusion electrode of the present invention for solving the above-mentioned problems has a fine hydrophilic part through which liquid can penetrate and a fine water-repellent layer through which gas can flow in and out, in the structure of a mesh of foam metal. It comprises a reaction layer in which parts are mixed in contact with each other and / or a gas diffusion layer in which fine water-repellent parts capable of gas flow are finely dispersed.

The method of manufacturing the gas diffusion electrode of the present invention is
A dispersion of the reaction layer raw material or /
And the dispersion of the gas diffusion layer raw material is poured to fill the reaction layer raw material or / and the gas diffusion layer raw material, and then this is dried, and then the surfactant is extracted and removed with an organic solvent, and then heated, After that, it is characterized in that it is pressure-molded by a roll and rapidly cooled.

[0007]

Since the skeleton of the gas diffusion electrode of the present invention having the above structure is made of foam metal, it has high strength, is not easily bent, is easy to handle, and can be upsized. Further, since the skeleton of the foamed metal has a large contact area as a current collector, it has good current collection efficiency and excellent electrode performance.

Further, in the method for producing the gas diffusion electrode of the present invention described above, the knitted structure of the foamed metal is filled with the dispersion liquid of the reaction layer raw material or the dispersion liquid of the gas diffusion layer raw material and dried to obtain the interfacial activity. Since the agent is extracted and removed with an organic solvent, the reaction layer raw material and the gas diffusion layer raw material do not flow, so it is easy to press-mold with a roll and rapidly cooled with a roll to obtain a gas diffusion electrode with the required thickness. Be done. Moreover, with a simple process, workability is good and it is suitable for mass production, and furthermore, a large gas diffusion electrode can be continuously and efficiently manufactured without using an expensive jig or hot press.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the gas diffusion electrode and the method for manufacturing the same according to the present invention will be described with reference to the drawings. Thickness 1 as shown in Figure 1
mm, length 200 mm, width 120 mm, and 0.1 mm to 0.2 mm in the stitch structure of Celmet 1 having a gas diffusion layer raw material dispersion, that is, water repellent carbon black with an average particle size of 420 Å and average particles. Polytetrafluoroethylene with a diameter of 0.3 μm was mixed at a ratio of 6.5: 3.5 with water and a surfactant to pour liquid into the Celmet 1 placed on the paper 12 while removing water from the upper part, and then reacted on it. Layer material dispersion, that is, platinum-supported (10%) hydrophilic carbon black and water-repellent carbon black with an average particle size of 420Å and average particle size
0.3 μm of polytetrafluoroethylene was poured at a ratio of 5: 3: 4 while removing a water content and a surfactant while removing water, and as shown in FIG. 2, the reaction layer raw material 2 and the gas diffusion layer raw material 3 And two layers were filled. Next, this was dried and then the surfactant Triton × 100 was extracted and removed with ethanol. Then, as shown in FIG. 3, it was heated in an electric furnace 11 at 380 ° C. in a stream of N ₂ . After that, the rolls 4 and 4 ′ are cooled and pressure-molded to a thickness of 0.5 mm.
Quenched at 4 '. The gas diffusion electrode 5 of the embodiment produced in this manner has a fine hydrophilic part 6 into which liquid can penetrate and a gas can flow in and out of the mesh structure of the celmet 1 as shown in a partially enlarged sectional view of FIG. A reaction layer 8 in which fine water-repellent portions 7 are mixed together and in contact with each other and a gas diffusion layer 10 in which fine water-repellent portions 9 through which gas can flow in and out are finely dispersed are formed in two layers. Has been done. The performance of the gas diffusion electrode 5 of this example was measured at 60 ° C. by supplying hydrogen and oxygen at 1 atm using a 25% KOH electrolytic solution.
It was cm ² and showed extremely high performance.

[0010]

As can be seen from the above description, the gas diffusion electrode of the present invention has a foam metal skeleton with high strength, is hard to bend, is convenient to handle, and can be made large in size. Since it has a large contact area as an electric body, it has good current collection efficiency and excellent electrode performance. In addition, the method for producing the gas diffusion electrode of the present invention comprises filling the dispersion structure of the reaction layer raw material or the dispersion liquid of the gas diffusion layer raw material in the structure of the metal foam, and drying the surfactant and then adding a surfactant to the organic solvent. Since the raw material for the reaction layer and the raw material for the gas diffusion layer do not flow because they are extracted and removed by, the pressure diffusion molding is easy with the roll, and the gas diffusion electrode with a required thickness can be rapidly cooled with the roll. Moreover, the process is simple, the workability is good, and it is suitable for mass production. Moreover, since an expensive jig or hot press is not used, a large gas diffusion electrode can be continuously and efficiently manufactured.

[Brief description of drawings]

FIG. 1 is a diagram showing steps of a method for manufacturing a gas diffusion electrode according to the present invention.

FIG. 2 is a diagram showing steps of a method for producing a gas diffusion electrode of the present invention.

FIG. 3 is a diagram showing steps of a method for producing a gas diffusion electrode of the present invention.

FIG. 4 is a partially enlarged sectional view of a gas diffusion electrode obtained by the manufacturing method of the present invention.

[Explanation of symbols]

 1 Celmet (foamed metal) 2 Raw material for reaction layer 3 Raw material for gas diffusion layer 4, 4'roll 5 Gas diffusion electrode 6 Hydrophilic portion 7 Water repellent portion 8 Reaction layer 9 Water repellent portion 10 Gas diffusion layer

Claims (2)

[Claims] 1. A reaction layer in which a fine hydrophilic portion through which a liquid can permeate and a fine water repellent portion through which a gas can flow in and out are mixed and in contact with each other in a mesh structure of a foam metal, and / or a flow in and out of a gas. A gas diffusion electrode which is filled with a gas diffusion layer in which possible fine water-repellent portions are finely dispersed. 2. The reaction layer raw material dispersion and / or the gas diffusion layer raw material dispersion is poured into the structure of the foam metal to fill the reaction layer raw material and / or the gas diffusion layer raw material,
Next, after drying this, the surfactant is extracted and removed with an organic solvent, followed by heating, followed by pressure molding with a roll and rapid cooling, which is a method for producing a gas diffusion electrode.