JPS6010424B2 - air battery - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in air electrodes for air batteries.

The air electrodes of conventional air batteries used catalysts such as metal phthalocyanine to strengthen the oxygen reduction ability of activated carbon, but metal phthalocyanines do not dissolve in water, so they dissolve into organic solvents such as quinoline. Activated carbon was soaked in this solution, pulled up and dried to scatter the organic solvent and deposit the catalyst on the surface of the activated carbon. However, since the amount of saturated melting was small, this operation was repeated several times to make about 10% of the catalyst by weight precipitate and coexist on the activated carbon. However, metal phthalocyaniso, which is the catalyst for conventional air batteries, is generally used as a pigment and is insoluble in most liquids, such as quinoline, NN, etc.
It was only soluble in very limited organic solvents such as -dimethylformamide and a-chlornaphthalene, and moreover, the amount dissolved at saturation was only 1 to 2% by weight based on the solvent.

Therefore, in order to deposit an effective amount of catalyst on activated carbon, the operations from impregnation with a solution to scattering and drying deposition of a solvent must be repeated about eight times, which is a laborious and time-consuming process.

In addition, in order to evaporate and scatter the organic solvent by drying, a temperature higher than the boiling point is required.
The boiling point of N-dimethylformamide is 153°C, and that of a-chlornaphthalene is 26°C, requiring the use of expensive equipment for drying.Furthermore, the vapor of the organic solvent that evaporates and scatters is hazardous to the human body for health and safety reasons. It had disadvantages such as undesirability. The purpose of the present invention is to use cobalt phthalocyanine having a sulfone group as a catalyst for the air electrode and to make the cobalt phthalocyanine soluble in water, thereby improving the amount of work in battery production and solving health and safety problems.

An embodiment of the present invention will be described with reference to FIG.

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 an air electrode which is in contact with a lyophilic semipermeable membrane 4.

5 is an electrolyte holding layer holding a caustic alkaline electrolyte, which is a nonwoven fabric or porous material with excellent liquid retention and liquid resistance;
It is in contact with the negative electrode body 6.

7 is paper with good air permeability, and is in contact with the air electrode through a polytetrafluoroethylene sheet 8 having many holes, and the other side is at the bottom of the cathode can 1 where air supply holes 2 are provided. are in contact with each other.

Reference numeral 9 denotes a negative electrode can, and the opening □ of the positive electrode can 1 is bent through a gasket 10 to seal the battery.

Air electrode 3 was prepared by soaking a nickel dawn stripe in an aqueous solution of cobalt phthalocyanine having a sulfon group of 8% by weight.
After drying at 0°C, it was soaked in polytetrafluoroethylene emulsion (3% water emulsion) and dried.

As shown in Figure 2, the cobalt phthalocyanine having a sulfon group used in the present invention is a phthalocyanine whose outer benzene ring is substituted with a hydrophilic sulfon group (-S0, Since cobalt phthalocyanine, which was previously insoluble in water, has a sulfon group and becomes water-soluble, impregnation of the catalyst can be carried out using an aqueous solution.

Further, the number of sulfon groups can be 1 to 4 per molecule of phthalocyanine, and any of them is effective as a catalyst for the air electrode 3. Although metal phthalocyanine with a sulfon group is water-soluble, ``when it comes into contact with the battery electrolyte, it hardly dissolves in the electrolyte because the concentration of salts such as caustic potassium in the electrolyte is very high, and the air electrode 3. In the present invention, cobalt phthalocyanine, which is a catalyst that is insoluble in water, is sulfonated and soluble in water, and the amount of solubility can be increased. The catalyst deposition operations from impregnation to dry deposition can be greatly reduced, thereby improving labor and time.

Furthermore, since water can be used as a solvent without using an organic solvent, only water vapor is scattered during drying, eliminating any health and safety problems. Furthermore, when the air electrode 3 to which the cobalt phthalocyanine catalyst having a sulfon group is attached is heat-treated in the range of 150 to 1300°C in an inert gas atmosphere such as nitrogen or argon, the storage performance of the battery is improved.
Figure 3 shows 20q of air electrodes [1] which were heat-treated for each female at 500°C and air electrodes [B] which were not heat-treated.
It is a comparison diagram of the discharge electrode line at the constant current density of oMhA/ground. Measurement of the sulfon groups in the catalyst of the heat-treated air electrode 3 reveals that the number has decreased compared to before the heat treatment, and as the sulfon groups in the catalyst decompose or scatter due to the heat treatment, part or most of the sulfon groups Cobalt phthalocyanine changes to cobalt phthalocyanine which is no longer oxidized, but when heated, cobalt phthalocyanine increases the number of highly covalent bonds, stabilizes it for a long time, and maintains its oxygen reduction ability for a long time. As described above, the air battery of the present invention using water-soluble cobalt phthalocyanine having a sulfone group as an air electrode catalyst improves the amount of work in battery manufacturing and solves health and safety issues. The industrial value is great.

Brief Description of the Drawings Figure 1 is a cross-sectional view of an air cell according to the present invention, Figure 2 is a structural diagram of cobalt phthalocyanine having a sulfon group, and Figure 3 is a mercury oxide standard with a heat-treated air electrode and an unheated air electrode. FIG. 3 is a comparison diagram of discharge curves for electrodes.

1... Positive electrode can, 2... Air supply hole, 3... Air electrode, 4. ...Semipermeable membrane, 6.Negative electrode body, 7.Paper, 8.
...Sheet.

Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. An air cell using a water-soluble cobalt phthalocyanine having a sulfone group as an air electrode catalyst.