JPH0132635B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to improvements in air electrodes for air batteries. The air electrode of conventional air batteries is made by mixing powdered activated carbon with a fine powder binder of polytetrafluoroethylene (PTFE), which has excellent water repellency, and forming the mixture into a thin plate and adding it to a current collector made of metal mesh such as stainless steel. They were pressed together to form a thin plate-like air electrode. However, when conventional air batteries are stored at high temperatures for long periods of time, the oxygen reduction ability of the activated carbon in the air electrode decreases.
This had the disadvantage that the discharge performance of the battery was extremely degraded. The reason for this is that during high-temperature storage, heavy metals such as zinc dissolved in the electrolyte and carbon dioxide gas in the atmosphere adsorb to the surface or active sites of activated carbon, severely deteriorating the capacity of the air electrode. It was hot. The present invention improves the storage characteristics of air batteries by using an air electrode made of a mixture of cobalt phthalocyanine and carbon black, which have an oxygen reducing power and are irradiated with microwave discharge plasma, and a water-repellent fluororesin. It is something. Embodiments of the present invention will be described based on the drawings. Reference numeral 1 denotes a positive electrode can that also serves as a positive electrode terminal, and has an air supply hole 2 at the bottom. 3 is made of a mixture of a cobalt phthalocyanine and carbon black irradiated with microwave discharge plasma at the air electrode and a water-repellent fluororesin binder, and the separator paper 4 is a lyophilic semipermeable membrane. are in contact with each other. Reference numeral 5 denotes an electrolyte holding material that holds an electrolyte containing 30% caustic potassium and zinc oxide, which 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. There is. Reference numeral 7 is paper with excellent air permeability, which is in contact with the air electrode 3 through a PTFE air-permeable membrane 8 having many micropores, and the other side of the cathode can 1 is provided with air supply holes 2. It touches the bottom. 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 sealing material that seals the air supply hole 2, and is stuck to the bottom of the positive electrode can 1 with a pressure-sensitive adhesive to seal the air supply hole 2. The air electrode 3 has a surface area of approximately
Using granular carbon black of 800 m ² /g, 2 g of cobalt phthalocyanine, which is a metal chelate compound, was dissolved in 300 c.c. of quinoline, and 10 g of carbon black was fully immersed in this solution, and then heated at 140°C while retaining the liquid. Dry under reduced pressure to evaporate the quinoline,
A cobalt phthalocyanine and carbon black coexistence is formed, and this coexistence is treated with microwave discharge plasma. In this case, the electromagnetic wave oscillation part of the plasma discharge treatment equipment is a 2450MHz microwave, _N2 is used for raw material processing, the gas pressure is 1 to 2 Torr, and the flow rate is
The output and processing time were set at 100 ml/min as follows. Output: 430 W, processing time: 8 minutes, sample rotation. In this case, the carbon black used for the air electrode 3 is subjected to concentrated high energy in microwave discharge plasma treatment, which distorts the crystal structure of the carbon black surface. Lattice defects are generated, and adsorption and desorption of atoms becomes active. Furthermore, the surface does not react uniformly, and a large number of specific points, that is, active points, appear strongly, and the catalytic action changes extremely strongly. The air electrode 3 made of such carbon black has the best oxygen reduction ability. Next, 2450MHz, output as an example of the present invention.
Using an air electrode obtained by mixing a cobalt phthalocyanine and carbon black coexistence that was irradiated with a 430W microwave discharge plasma and a water-repellent fluororesin PTFE, a 30% caustic potassium electrolyte was used. The product of the present invention [A], which is a button-type air cell with a size of 5.2 mm and the height of 5.2 mm, and the conventional product [B], which is an air cell of the same type without being exposed to microwave discharge plasma irradiation, are 10 pieces, initially at 25℃
The discharge capacity was measured by discharging at a constant current of 1.5 mA.
In addition, 20 pieces of the invention product [A] and 20 pieces of the conventional product [B] were combined into 45 pieces.
Store at ℃, 10 pieces each at 6th and 12th month
The battery was discharged at a constant current of 1.5 mA at °C, and the duration of the discharge was measured. The following table summarizes the measurement results.

[Table] From this table, it can be seen that the product [A] of the present invention has a long discharge duration after storage and has excellent storage performance. As described above, the air battery of the present invention using an air electrode having an oxygen reduction ability that has been irradiated with micro-discharge wave plasma has excellent storage performance.

[Brief explanation of drawings]

The figure is a cross-sectional view of a button-type air battery using the air electrode obtained in an example of the present invention. 3...Air pole.

Claims (1)

[Claims] 1. A step of applying microwave discharge plasma irradiation to a cobalt phthalocyanine and carbon black coexisting material having oxygen reducing power, and a step of mixing the coexisting material subjected to the microwave discharge plasma irradiation with a water-repellent fluororesin. A method for producing an air electrode characterized by having the following.