JPH0119626B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing an air electrode used in air cells, fuel cells, and the like. Conventionally, the air electrodes of air cells and fuel cells have used metal phthalocyanine as a catalyst to increase the ability to reduce oxygen to carbon materials such as carbon black and activated carbon. Dissolved in special organic solvent,
A carbon body was immersed in this solution, and after drying, the organic solvent was scattered to impregnate the carbon body with metal phthalocyanine, but this method had the following drawbacks. That is, the organic solvents used to dissolve metal phthalocyanine, such as quinoline, N/N-dimethylformamide, and α-chloronaphthalene, have a solubility of 1% or less for metal phthalocyanine, so they do not contain the required amount of metal in the carbon body. In order to impregnate phthalocyanine, it is necessary to repeat impregnation with the solution and removal of the solvent many times, and each solvent has a boiling point other than N-N-dimethylformamide (153°C), quinoline (238°C), Like α-chlornaphthalene (263°C), the temperature is over 200°C, making it extremely difficult to dry and requiring the use of expensive equipment. The present inventors have conducted various studies on solvents for metal phthalocyanine, and as a result, have found that halogenoacetic acid is suitable, and have finally completed the present invention.That is, the present invention has been made by converting metal phthalocyanine into halogenoacetic acid. The gist of the present invention is a method for producing an air electrode, which is characterized by dissolving the material and impregnating it into a carbon body. Since the halogenoacetic acid used as a solvent for the metal phthalocyanine of the present invention has a solubility in the metal phthalocyanine of 5 to 10%, it is easy to impregnate the carbon body with the required amount of metal phthalocyanine, and the boiling point is 200°C. If the following halogenoacetic acid is used, drying is easy and expensive equipment is not required, making it easy to manufacture an air battery. Hereinafter, the present invention will be explained in detail according to the composition. Examples of metal phthalocyanine include transition metal iron,
Phthalocyanines such as nickel and copper are used,
Preferably, the purity is 90% or more when recrystallized from 95% sulfuric acid. As the halogenoacetic acid used to dissolve the metal phthalocyanine, the fluoro and chloride derivatives shown in the table below are preferably used.

[Table] Carbon materials used include carbon blacks such as furnace black, channel black, and thermal black, as well as wood, charcoal, coconut shell charcoal, palm kernel charcoal, coal, petroleum residue, synthetic resin, and organic waste. Examples include one type or a mixture of two or more of activated carbon and graphite made using carbon and graphite, and are formed into a certain shape by extrusion molding, injection molding, pressure molding, etc. as necessary. The above-mentioned metal phthalocyanine is dissolved in halogenoacetic acid to obtain a 5-10% metal phthalocyanine solution, this solution is impregnated with a carbon material, and the halogenoacetic acid is removed by a conventional method to obtain the desired air electrode. Hereinafter, it will be explained in more detail according to Examples, and in the Examples, "parts" indicate "parts by weight". Example 1 10 parts of coconut shell activated carbon with a particle size of 0.1 to 1μ, particle size of 0.1 to 1μ
10 parts of 0.5μ graphite and 5 parts of thermoplastic resin (vinyl chloride resin) are mixed and extruded to make a round bar with a diameter of 10 mm.Then, the thermoplastic resin is decomposed by heat treatment at 200°C to form a carbon body. And so. This carbon body is immersed in a trifluoroacetic acid solution (boiling point 72°C) in which 10% by weight of iron phthalocyanine is dissolved, and then vacuum-dried at 50°C to attach 5% by weight of iron phthalocyanine/sulfonic acid to the carbon body. Obtained an air electrode. Example 2 A trichloroacetic acid solution (boiling point 197°C) in which the carbon body of Example 1 was dissolved with 8% by weight of copper phthalocyanine
The carbon body was immersed in water and then vacuum dried at 100°C to obtain an air electrode in which 3% by weight of copper phthalocyanine was adhered to the carbon body. Comparative Example 1 The carbon body of Example 1 was immersed in a saturated quinoline solution of copper phthalocyanine, and then vacuum-dried at 150°C to obtain an air electrode with copper phthalocyanine attached to the carbon body. Comparative Example 2 The operation of Comparative Example 1 was repeated twice to prepare an air electrode. The polarization characteristics of the air electrodes obtained in Examples 1 and 2 and Comparative Examples 1 and 2 are shown in FIGS. 1 and 2. As described above, the air electrode obtained by the present invention has excellent polarization characteristics because the carbon body is impregnated with an appropriate amount of metal phthalocyanine as a catalyst in a single treatment, and is suitable for use in air cells, fuel cells, etc. Although it is suitable for an air electrode, repeated treatment does not change the gist of the present invention in any way.

[Brief explanation of drawings]

Fig. 1 shows the polarization curve of the air electrode obtained in Example 1 and Comparative Example 1, and Fig. 2 shows the polarization curve of the air electrode obtained in Example 2 and Comparative Example 2. The polarization curves of the air electrodes obtained in Example 1, Comparative Example 1, Example 2, and Comparative Example 2 are shown, where the vertical axis represents the current density (mA/cm ² ) and the horizontal axis represents the potential (V/SCE). It shows.

Claims (1)

[Claims] 1. A method for producing an air electrode, which comprises dissolving metal phthalocyanine in halogenoacetic acid and impregnating it into a carbon body. 2. The method for producing an air electrode according to claim 1, wherein the metal phthalocyanine contains iron, nickel, cobalt, and copper. 3. Claim 1 or 2, wherein the halogenoacetic acid is at least one of monofluoroacetic acid, difluoroacetic acid, trifluoroacetic acid, monochloroacetic acid, dichloroacetic acid, and trichloroacetic acid.
2. Method for manufacturing an air electrode as described in Section 1.