JPS6298563A - Manufacture of anode plate for nickel-cadmium alkaline storage battery - Google Patents

Abstract

PURPOSE:To increase oxygen gas absorbing capability to reduce an increase in internal pressure in a battery during quick charge-discharge by using hydrophilic and hydrophobic binders. CONSTITUTION:Cadmium oxide powder and a hydrophobic binder are mixed in a dry process, and the mixture is kneaded with a solvent in which a hydrophilic binder is dissolved, then the kneaded mixture is applied to a grid to manufacture an anode plate. For example, 73pts. cadmium oxide powder and 2pts. polytetrafluoroethylene are mixed for 30min in a dry process. A solution obtained by dissolving 23pts. ethylene glycol and 2pts. polyvinyl alcohol is added to the mixture, and they are kneaded 2hr at 20+ or -2 deg.C to obtain paste. 11.8g of the paste is applied to punched nickel plate measuring 34mmX200mm and dried at 100 deg.C until generation of white vapor of ethylene glycol stops. 11.8g of the paste is equivalent to 3.6Ah of the capacity of anode active material. This anode plate is coupled with a cathode plate having a capacity of 1.2Ah to form a battery.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improvement in the manufacturing method of a cathode plate for a nickel-cadmium alkaline storage battery, and particularly relates to charging characteristics during rapid charging.

Conventional technology In conventional nickel-cadmium alkaline storage batteries, the cathode plate is a sintered type in which the active material cadmium hydroxide or metal cadmium is chemically or electrochemically retained in the pores of a nickel sintered body. was the majority. Recently, due to the increase in the capacity of batteries and the development of new manufacturing methods, bunching metal I is produced by kneading cadmium oxide powder with melted binder powder or dispersion of binder powder and using it as a core material. A cathode plate manufacturing method called a paste method or a slurry method is attracting attention.

Problems to be Solved by the Invention The binder powder used in the paste type or slurry type cathode plate manufacturing method can be either hydrophilic or hydrophobic. As mentioned above, methylcellulose, polyvinyl alcohol, and the like are known as hydrophilic binders, which are used by melting them in water, ethylene glycol, or the like. Therefore, the surface of the cadmium oxide powder, which is the active material, is coated.

On the other hand, the rapid charging characteristics depend on how efficiently the cathode plate absorbs the oxygen generated from the anode force (7)). This gas absorption occurs most efficiently at the three-phase interface of @polar active material, electrolyte, and intoxicant. Therefore, as mentioned above, if the surface of the active material is covered with a hydrophilic binder, this film will slow down the movement of oxygen gas to the cadmium surface.
At 11<, the binder is completely leaked by the electrolyte, making it very difficult to form the three-phase interface described above.For this reason, when using a hydrophilic binder, it is difficult to form a three-phase interface. It is extremely difficult to manufacture a cathode plate that satisfies the charging characteristics.On the other hand, hydrophobic binder powders include polytetrafluoroethylene, which can be mixed with water or ethylene/toluene. This binder does not completely coat the surface of the active material and is difficult to cover with the electrolyte, making it difficult to form a three-phase interface. ,
The ability of the cathode plate to absorb oxygen gas increases, allowing rapid charging. However, when oxidized rum is kneaded with a dispersion of this binder, it becomes gum-like, which is no problem at the experimental level, but it is extremely difficult to produce at the final stage.

In producing these three cathode plates capable of rapid charging, there have been problems in terms of performance and manufacturing, depending on the type of binder.

problem? Means for Solving the Problem In view of the above-mentioned problems, the present invention involves dry mixing cadmium oxide powder and hydrophobic binder powder, then kneading with a solvent in which the hydrophilic binder is melted, and applying the mixture to the core material.
Thus, when producing a cathode plate, a hydrophobic binder can be dispersed on the cadmium surface covered with a hydrophilic binder, forming a three-phase interface for oxygen gas absorption. . Also, since the hydrophobic binder is dry mixed, unlike a dispersion, it does not come out in the form of a gum, but rather in the form of a paste or slurry. ! There is no problem with the physical aspect.

EXAMPLE 73 parts of cadmium oxide powder and 2 parts of polytetrafluoroethylene were mixed for 30 minutes. Then 23 parts of ethylene glycol and 2 parts of polyvinyl alcohol? Add the molten solution and knead for 2 hours. The temperature at this time is 20 parts 2
It is ℃.

This paste 'i:' 34 ram X 200 m
Thick m! 11.8 on nickel punched metal
The paste of f was applied and dried at a drying temperature of H1oo°C until no white vapor of ethylene glycol was emitted. The paste amount of 11.8SF is equivalent to the cathode active material guest t3°5Ah. This cathode plate and a 1,2 Ahcv anode plate were assembled to form a battery.

The south side shows the results of comparing the battery internal pressures during charging between Battery A according to the present invention manufactured in this manner and Battery B using a cathode plate manufactured using only a conventional hydrophilic binder. The photoelectric current at this time is 0.5 crrA
It is. Since the anode plate is almost completely charged after 2 hours of photovoltaic time, oxygen gas is generated from the anode. In conventional battery B, the internal pressure of the battery can rises and falls because the absorption of oxygen gas by the cathode plate does not proceed much. On the other hand, in the electrolyte oil A according to the present invention, the oxygen gas absorption reaction progresses at a lower rate, so the internal pressure of the battery can decreases to about 2 K.
It is almost constant at q/tri.

As stated above, the present invention improves the oxygen gas absorption ability of the cathode plate and reduces the internal pressure of the IT battery can during rapid charging. The industrial value can be kept low, and the production value is not extremely difficult or difficult to produce as when a hydrophobic binder dispersion is used.

[Brief explanation of drawings]

Figure 1 is a T-curve diagram showing the change in battery can internal pressure over time for battery B using a conventional electrode plate and battery A using an electrode plate according to the present invention E.

Claims (1)

[Claims] A method for producing a cathode plate for a nickel-cadmium alkaline storage battery, characterized by using a hydrophilic and hydrophobic binder.