JPS5948510B2 - air battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the improvement of the air electrode of an air battery, and its purpose is to improve the storage performance of the battery.

Conventional air batteries use an air electrode made by mixing powdered activated carbon or granular activated carbon with a water-repellent binder such as polytetrafluoroethylene powder, and press-molding the mixture into a thin plate shape on a conductor such as nickel net. Ta.

The disadvantage of the above-mentioned conventional battery is that during long-term storage, the activity of the activated carbon surface deteriorates, reducing the oxygen reduction ability and causing the battery to deteriorate.

In order to improve this, catalysts such as N2', '-tedium, and platinum were added and mixed to maintain the oxygen reduction ability.
The amount added has increased, making it expensive.

The purpose of the present invention is to obtain an air battery that is inexpensive and has good characteristics in long-term storage and long-term discharge with a weak battery, using an air electrode that coexists with a sulfate such as cobalt phthalocyanine having a sulfonic group. It is.
Embodiments of the present invention will be described based on the drawings.

1 is a positive electrode can that also serves as a positive electrode terminal, and an air supply hole 2 is provided at the bottom; 3 is an air electrode, which is in contact with the bottom of the positive electrode can 1 and reinforced on both sides with conductive porous reinforcing material 4 such as stainless steel net. , the peripheral portion is fixed by pressure contact with a gasket 5.

Reference numeral 6 denotes an electrolyte retaining layer impregnated with a caustic gel electrolyte having a viscosity of 10,000 centipoise, which is a nonwoven fabric or porous material with excellent retention and liquid resistance, and is provided between the negative electrode body 7 and the air electrode 3. It is intervening.

A negative electrode can 8 also serves as a negative electrode terminal, and the opening of the positive electrode can 1 is bent through a gasket 5 to seal the battery.

Inside the air supply hole 2, a liquid-absorbing paper 9 is interposed so that the electrolyte does not leak out, and absorbs the leaking electrolyte. Furthermore, a sealing material 10 is attached to the outside of the air supply hole 2 to prevent air from flowing in, so that the air electrode 3 will not deteriorate due to the influence of carbon dioxide gas during storage.

The air electrode 3 has a surface area of about 800 go/cm by gas adsorption method.
Using 3g of granular activated carbon, 2g of cobalt phthalocyanine having a hydrophilic sulfone group and 4g of sodium sulfate O.
Dissolve g in 200 cc of water, and add 10 g of activated carbon to this solution.
After fully immersing the material, the water is dried under reduced pressure at 100°C in a water-holding state to evaporate the water, forming a cobalt phthalocyanine, sodium sulfate, and activated carbon coexistence, which is then heat-treated in an electric furnace to form a polyester. An air electrode is formed by sandwiching a material treated with a tetrafluoroethylene emulsion from both sides with stainless steel nets. Heat treatment is performed at 150℃~B (
company) to ℃. In the present invention, cobalt phthalocyanine is mixed with sulfate and heat treated.
It is cheaper than precious metal catalysts, has stronger oxygen reduction ability, lasts for a long time, has less deterioration, and improves the long-term discharge and long-term storage performance of batteries.

This is because the waste matter adsorbed on the activated carbon surface is replaced by sulfate radicals, increasing the number of active sites and improving the active ability of the catalyst, that is, the oxygen reduction ability. Further, the catalyst changes into a highly covalent bond by the heat treatment, and the activity remains stable.

However, if the temperature is lower than 150°C, the co-yoke does not proceed, so it is not very effective, and if the temperature exceeds 1300°C, the cobalt phthalocyanine is significantly sublimated by heat, so that the expected effect could not be obtained. It should be noted that when the heat treatment was carried out in an inert gas such as nitrogen or argon, a reducing gas such as hydrogen, or in a vacuum, the weight loss due to oxidation was less and the effect was better. The example battery of the present invention used sulfonated cobalt phthalocyanine as shown in the formula below, where n=1 to 4. Some Fe, Ni, Mg,
Similar effects were obtained with Cu and Mn.

Furthermore, in addition to the phthalocyanine ring, similar effects were obtained with the porphyrin ring (Hohin ring) as shown in the following formula. n = 1 to 4 Similarly, excellent effects as air electrodes were obtained with ammonium salts.

In addition, the present invention processes the activated carbon surface to make it water-repellent and adds viscosity to the electrolytic solution. Through wetting due to penetrating force and surface tension, an extremely thin layer of electrolytic solution is formed on the activated carbon surface, maintaining high oxygen reduction ability. Moreover, since a wide discharge area can be ensured, high performance can be obtained in air batteries.

Furthermore, a substance having a nobler potential than oxygen, such as manganese dioxide, nickel oxyhydroxide, silver oxide, etc., is further coexisted in the air electrode made of activated carbon coexisting with the cobalt phthalonanine and sulfate, and the voltage is increased. It was also confirmed that the air electrode operated normally.

Next, an air electrode made of cobalt phthalocyanine, sodium sulfate, and activated carbon according to the present invention and a caustic potash electrolyte with a viscosity of 10,000 centipoise were used.
A button-type air battery of the present invention with a size of 5.2 mm and a height of 5.2 mm [A] and a conventional product of the same type air battery using a conventional activated carbon air electrode [B] A cobalt phthalocyanine having a sulfone group. Thirty pieces of each of the conventional product [C] used were stored at 25°C, and 10 pieces of each were discharged at a constant current of 1.5 mA every 6 months and 12 months.
Table 1 shows the discharge capacity maintenance rate with respect to the initial stage.

In addition, Table 2 shows the results of calculating the capacitance efficiency of the air electrode from the zinc utilization efficiency by discharging with a weak current of 0.1 mA for a long period of time.
It was shown to.

According to Table 1, the air battery of the present invention has excellent storage performance,
Table 2 shows that it can withstand long-term discharge with a weak current.

As described above, an air battery using an air electrode in which cobalt phthalocyanine having a sulfone group, sulfate, and activated carbon coexist is inexpensive and has good characteristics in long-term storage and long-term discharge with weak current. The industrial value is great.

[Brief explanation of the drawing]

The figure is a cross-sectional view of an embodiment of an air battery according to the present invention. DESCRIPTION OF SYMBOLS 1... Positive electrode can, 2... Air supply hole, 3... Air electrode, 4... Porous reinforcement body, 6... Electrolyte holding layer,
7... Negative electrode body, 10... Sealing material.

Claims (1)

[Scope of Claims] 1. An air battery characterized by using an air electrode in which cobalt phthalocyanine having a sulfone group, sulfate, and activated carbon coexist. 2. The air battery according to claim 1, wherein the sulfate is sodium sulfate.