JPS648430B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an anode having a novel composition for air batteries, and more specifically to an unfired electrode in which a resin is mixed with activated carbon and then heated and solidified. The present invention relates to a configuration of a positive electrode that can maintain discharge current density and control permeation of electrolyte. An air battery is a primary battery that uses oxygen in the air as a depolarizing agent, and has a composition of (air - carbon | electrolyte | zinc), but the permeation rate of the electrolyte is low when the carbon electrode is not waterproof. In the case of fired electrodes, the electrodes are immersed in a solution of waterproofing agent such as paraffin or resin, and then the solvent is evaporated and a thin waterproof membrane is coated to control the penetration of the electrolyte. In the case of unfired electrodes, activated carbon and resin solution are kneaded and molded and then dried and solidified, or
The process involves mixing colloidal resin powder of 0.5 μm or less with activated carbon and heating it to simultaneously generate and solidify a waterproof film. In short, all of the above methods are based on the principle of coating the carbon surface with a thin waterproof film to control penetration of the electrolyte into the electrode. On the other hand, the present invention differs from the known methods described above in principle, by appropriately selecting and blending the particle diameters of resin particles and activated carbon, and heating and welding them after mixing. By examining the blending ratio of raw material components, we were able to obtain a strong electrode with a high electromotive force and a slow permeation rate of electrolyte, which we have put to practical use. That is, the present invention uses activated carbon with a particle size of 200 mesh or less and two types of resins with particle sizes of 100 mesh or less and 300 mesh or less as raw materials. After mixing these three types of raw materials, they are heated and welded, and as shown in the attached drawings. As explained, molding is performed by forming a state in which resins of two types of particle sizes, large and small, are mixed and deposited in the activated carbon layer. It is difficult to find a critical range for the blending ratio of these three types of raw materials, but preferably activated carbon is 75-80% by weight, resin with a particle size of 300 mesh or less is 13-17% by weight, and resin with a particle size of 100 mesh or less is 3-3% by weight. A range of 12% by weight is recommended. To illustrate an example of the implementation of the present invention, 75% by weight of activated carbon with a particle size of 200 mesh or less, 15% by weight of polyethylene with a particle size of 2 to 40μ, and 10% by weight of polyethylene with a particle size of 100 to 200 mesh are mixed, and the mixture is placed in a molding machine. Heat at 120 to 130°C for 5 to 50 minutes while applying approximately 500g of pressure per ^1cm2 .
Heat for 10 minutes and then let cool. One side of the flat anode with a thickness of 1.7 mm thus obtained was used as the air-facing surface, the other side was used as the liquid-facing surface, and zinc was used as the cathode.
A battery of a known type using caustic soda or caustic potash solution as the electrolyte was assembled and discharged at a constant current density until the voltage suddenly decreased.The performance of the battery at that time was determined as follows.

[Table] In contrast, the performance of commercially available unfired batteries was as follows:

[Table] From Tables 1 and 2 above, for the same current density, electric capacity, and liquid immersion area, the thickness of the electrode according to the present invention is 1.7 mm, but the thickness of the commercially available product is 10 mm. This indicates that the electrolyte permeation rate is slow. In addition, the practical current density of conventional air batteries is said to be a maximum of approximately 5mA/ ^cm2 , but the product of the present invention
The fact that it can be used even at 10 mA/cm ² can be said to be an indication of the superiority of the present invention.

[Brief explanation of drawings]

The drawing is an enlarged model diagram of a part of the structure of the electrode of the present invention.
In the figure, large black dots indicate resin particles with a particle size of 100 mesh or less, small particles indicate resin particles with a particle size of 300 mesh or less, and medium black dots indicate activated carbon particles with a particle size of 200 mesh or less.

Claims (1)

[Claims] 1. An unfired electrode in which a resin is mixed with activated carbon and solidified by heating, and the resin has two types of particle sizes: 300 mesh or less and 100 mesh or less, and the activated carbon has a particle size of 200 mesh or less. An anode for an air battery characterized by: 2 Resin particle size of 300 mesh or less 13 to 17
The air according to claim 1 is characterized in that the blending ratio is 3 to 12% by weight of particles having the same particle size of 100 mesh or less and 75 to 80% by weight of activated carbon particles having a particle size of 200 mesh. Anode for batteries.