JPS6228548B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an air battery having an air electrode that uses oxygen in the air as an active substance, and provides a high-voltage, high-capacity air battery by using an electrolyte containing a mixture of zinc perchlorate and sulfamic acid. . Conventional air batteries use oxygen as the positive electrode active material and zinc as the negative electrode active material, and the electrolyte is a 30-40% caustic alkali aqueous solution such as caustic soda or caustic potash saturated with zinc oxide. By adding viscosity with a glue such as sodium acrylate and thickly covering the surface of the air electrode to prevent the oxygen reduction ability from decreasing, and by preventing leakage from the air supply hole in the positive electrode can, the battery can be miniaturized and sealed. was. Conventional air batteries use an alkaline electrolyte such as caustic potash, and during storage or discharge, a large amount of carbon dioxide gas flows in from the air supply hole in addition to oxygen, so the electrolyte comes into contact with carbon dioxide gas, and the caustic potassium in the liquid is mixed with the electrolyte. The reaction produced a large amount of potassium carbonate. As a result, the alkaline concentration of the electrolyte decreased, resulting in a decrease in electrical conductivity and a decrease in the discharge operating voltage of the battery. Furthermore, the alkaline electrolyte dissolved zincate ions generated by the zinc discharge reaction to near saturation, and when a large amount of carbon dioxide gas entered, it reacted with the zincate ions in the solution, producing a large amount of zinc carbonate. Zinc carbonate has a low solubility in the electrolytic solution and deposits on the zinc surface, reducing the discharge reaction area, resulting in disadvantages such as a decrease in discharge operating voltage and a decrease in discharge capacity. As an improvement to this, large air batteries circulated the electrolyte using a pump, etc., and used calcium hydroxide to regenerate the alkali carbonate into new alkali, but this required large equipment, and it was difficult to miniaturize the battery. There were many difficulties. The object of the present invention is to obtain a high-voltage, large-capacity air battery by using an acidic electrolyte consisting of an aqueous perchlorate solution. Embodiments of the present invention will be described based on the drawings. Reference numeral 1 denotes a positive electrode can which also serves as a positive electrode terminal, and has an air supply hole 2 at the bottom. The air electrode 3 is made of cobalt phthalocyanine, activated carbon, and water-repellent fluororesin, and is in contact with the separator paper 4, which is a lyophilic semipermeable membrane. 5 is zinc perchlorate and sulfamic acid 10:
This is an electrolyte holding material that holds an acidic electrolyte mixed at a ratio of 11 to 11. It is a nonwoven fabric or porous material with excellent liquid retention and acid resistance, and is in contact with the negative electrode body 6 made of zinc powder. Reference numeral 7 is paper with excellent air permeability, which is in contact with the air electrode 3 through an air-permeable membrane 8 made of polytetrafluoroethylene having many micropores, and the other side is a positive electrode can provided with air supply holes 2. It is in contact with the bottom of 1. 9 is a negative electrode can, and the opening of the positive electrode can 1 is bent through a gasket 10 to seal the battery.
Reference numeral 11 denotes a polyvinyl chloride sheet sealant that seals the air supply hole 2, and a pressure-sensitive adhesive 12 seals the air supply hole 2 at the bottom of the positive electrode can 1. The air electrode 3 has a surface area of approximately
Using granular carbon black of 800 m ² /g, dissolve 2 g of cobalt phthalocyanine, a metal chelate compound, in 300 c.c. of quinoline, thoroughly soak 10 g of activated carbon in this solution, and leave it in the liquid state.
Dry under reduced pressure at 140°C to evaporate quinoline, form a cobalt phthalocyanine and carbon black coexistence, heat treat in an electric furnace, treat with polytetrafluoroethylene emulsion, and then use a stainless steel net. It is sandwiched from both sides to form an air electrode. Especially, 150℃~1300℃
It is thought that those heat-treated at temperatures between 0.degree. However, at temperatures below 150°C, the co-yoke does not proceed, so not much effect was observed, and at temperatures above 1,300°C, the metal chelate compound sublimated significantly due to heat, so 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. Since the battery of the present invention uses an acidic electrolyte of zinc perchlorate and sulfamic acid, there is no generation of carbonates due to a large amount of carbon dioxide gas other than oxygen flowing in from the air supply hole 2 of the positive electrode can 1. Since the electrolytic solution does not deteriorate, there is no drop in the battery discharge operating voltage, and since there is no precipitate, there is no decrease in discharge capacity, and a high-voltage, large-capacity air battery can be obtained. Furthermore, when a mixed aqueous solution (PH of 1) of zinc perchlorate and sulfamic acid is used as the electrolyte of the battery of the present invention, the theoretical reduction potential of oxygen is +1.23V with respect to the hydrogen electrode, and the oxidation potential of zinc is -0.76V, the theoretical potential difference of the battery is 1.99V, and the operating voltage is approximately 1.5V due to polarization due to discharge. This is because the oxygen reduction potential in an alkaline electrolyte of PH15 is +0.40V, the oxidation potential of zinc is -1.32V, the theoretical potential difference of the battery is 1.72V, and the discharge operation voltage is approximately 1.3V due to polarization. The voltage increases by 0.2V, and an air battery with high voltage and large capacity can be obtained by that increase. In addition, since perchlorate is an oxidizing salt, it can sufficiently protect stainless steel even in acidic atmospheres, and is stable even at air electrode potential. It is possible to make the positive electrode can 1 which also serves as a positive electrode can. Next, a button-shaped air battery with a diameter of 11.5 mm and a height of 5.2 mm using an acidic electrolyte of a mixed aqueous solution of zinc perchlorate and sulfamic acid with pH = 1, which is an example battery according to the present invention, was used. Certain invention product [A]
and the conventional product [B], which is the same type of air battery using an alkaline electrolyte of caustic potassium aqueous solution with pH = 15, were discharged at 25°C with a constant current of 1.5 mA, and the discharge curve was plotted. The discharge capacities are summarized in Table 1 in FIG. In addition, 20 pieces of the invention product [A] and 20 pieces of the conventional product [B]
20 pieces were stored at 25℃, and 10 pieces each were stored at 6th and 12th months.
The cells were discharged at a constant current of 1.5 mA at 25°C, and the results are summarized in Table 1.

[Table] From FIG. 2 and Table 1, it can be seen that the product [A] of the present invention has a high discharge operating voltage, a long duration, and excellent storage performance. In addition, since the air battery of the present invention has an operating voltage of 1.5V, it can be used as an alkaline manganese battery, a silver oxide battery, or
It is compatible with nickel zinc batteries, etc. As described above, an air electrode made of a metal chelate compound, carbonaceous material, and water-repellent fluororesin, an acidic electrolyte made of a mixture of zinc perchlorate and sulfamic acid, and a zinc negative electrode body are connected to a positive electrode having air supply holes. The air battery of the present invention, which is inserted into a can and sealed with a gasket and a negative electrode can, has a high discharge operating voltage and an improved discharge capacity.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an air battery according to an embodiment of the present invention.
Figure 2 shows the inventive product [A] and the conventional product [B] at 25°C.
It is a comparison diagram of discharge curves of 1.5mA constant current. DESCRIPTION OF SYMBOLS 1... Positive electrode can, 2... Air supply hole, 3... Air electrode, 5... Electrolyte holding material, 6... Negative electrode body.

Claims (1)

[Scope of Claims] 1. An air cell comprising an air electrode made of a metal chelate compound, carbonaceous material, and water-repellent fluororesin, an acidic electrolyte solution made of a mixture of zinc perchlorate and sulfamic acid, and a zinc negative electrode. 2. The air battery according to claim 1, wherein the air electrode is housed in a stainless steel positive electrode can.