JPS5882476A - Production method of button type alkaline battery - Google Patents

Abstract

PURPOSE:To improve the resistance against liquid leakage and stabilize the short-circuit current for the battery performance by assembling the battery after fixing a seperator by dropping a viscous solution which is made by adding a thickner in an alkaline solution on the surface of positive electrode depolarizing mix and removing various unstable factors caused by a shift of the position of the separator. CONSTITUTION:A desirable amount of a mixture 3 of hardened zinc powder, and carboxy-methyl cellulose powder is put into the assembled sealed plate which is used as a container, and also being used as a negative terminal, which is made by fitting insulating sealing ring 1 on which an sealing agent is painted, to the periphery of sealing plate 2; then a material to be impregnated 4 is placed; and a desirable amount of electrolyte solution which contains potassium hydroxide is poured. Then, a specified amount of positive electrode depolarizing mix 6 is inserted in the positive electrode case 5 having a step, and pressured. High viscous solution 7 which is made by adding the thickener into an alkaline solution is dropped on the surface of positive electrode, and the separator 8 is fixed, then, a battery is assembled by combining a negative electrode and a positive electrode.

Description

[Detailed Description of the Invention] The present invention relates to a method for manufacturing button-type alkaline batteries, and in particular, a method for manufacturing button-type alkaline batteries that has excellent mass productivity and storage stability by improving the separator insertion method when the side surface of the positive electrode case is stepped. It provides:

The separator insertion methods for conventional button-type alkaline batteries are roughly classified into the following two methods.

The first method is to insert the positive electrode mixture into the positive electrode case and pressurize it, then inject a predetermined amount of an electrolytic solution consisting of an aqueous potassium hydroxide solution, and then insert the separator into the positive electrode case. This method is widely used in current button-type alkaline batteries.

The second method is to mix zinc hydrate powder and a thickener, mainly carboxymethyl cellulose powder, insert the desired amount into the negative electrode sealing plate, then place the impregnating material and add potassium hydroxide. A predetermined amount of an aqueous electrolytic solution is injected into the negative electrode sealing plate, and then a separator is inserted onto the impregnated material.

The current method of manufacturing button-type alkaline batteries using stepped positive electrode cases mainly uses the second method, but this method has the following problems.

In other words, since the separator is simply placed on the surface of the impregnated material, the paste tends to be misaligned in the center of the negative electrode sealing plate, as shown in Figure 5, which tends to occur after assembly as shown in Figure 6. This can easily become an obstacle to mass production during the manufacturing process or cause variations in quality characteristics.

Furthermore, in the first method, because of the stepped case, the separator is likely to come off the case during the manufacturing process, making mass production impossible.

As mentioned above, with the conventional method, there was a problem within the ridge when inserting the separator into the stepped positive electrode case.

The present inventors propose a separator insertion method that solves these problems.

The present invention will be explained in detail below.

An insulating sealing ring 1 coated with a sealant is attached to the periphery of a sealing plate 2, and a desired amount of a mixture 3 of electrolytic zinc powder and carboxymethyl cellulose powder is inserted into the assembled sealing plate, which serves as a container that also serves as a negative electrode terminal. After that, the impregnating material 4 is placed, and a desired amount of electrolytic solution consisting of potassium hydroxide is injected.
As shown in the figure.

Next, add a predetermined amount of positive electrode mixture 6 to the stepped positive electrode case 6.
After the positive electrode is inserted and pressurized, a highly viscous solution 7 made by adding a thickener to an alkaline solution is dropped onto the surface of the positive electrode to adhere the separator 8, resulting in the state shown in FIG. A battery as shown in FIG. 3 is assembled by combining the negative electrode shown in FIG. 1 and the positive electrode shown in FIG. 2.

It was found that it is possible to improve the leakage resistance and stabilize the short circuit current in terms of battery performance.

Next, a specific example will be described.

JIS standard (7) MB2 type (HD), diameter 16. .

A case will be described in which the present invention is applied to a mercury battery with a height of 6.2 cm.

As shown in FIG. 4, an aqueous potassium hydroxide solution 7 containing 1.5 weight percent of carboxymethyl cellulose powder is dropped onto the surface of the 101'1jp IF electrode in the stepped positive electrode case 6 shown in FIG. Next, insert alkali-resistant separator No. 8.

For the positive electrode, a desired amount of positive electrode mixture 6, which is a mixture of mercury oxide and graphite powder, is weighed and press-molded in a stepped case 6 is used.

On the negative electrode side, as shown in FIG. 1, the negative electrode sealing plate 2 is mainly formed of a stainless steel plate, and a clad plate with copper on the inner surface and nickel on the outer surface is used.

The insulating ring 1 was made of boria 1-mid (6,6 nylon). Further, a sealant was applied in advance to the surface where the sealing ring and the sealing plate were in contact.

Inside the sealing plate 1 is an electrolytic solution consisting of 440gf of negative electrode mixture 3, which is a mixture of frozen zinc powder (freezing rate: 11%) and carboxymethyl cellulose powder as a thickener in proportion to 2 of the total weight, and potassium hydroxide. The desired amount was injected to form a gel. An electrolyte holding material 4 made of alkali-resistant fiber is placed on this negative electrode mixture 3.

A battery is made by combining the negative electrode configuration shown in FIG. 1 and the positive electrode configuration shown in FIG. 2 explained above.

The battery obtained by trial production in this way was heated to 60℃ at a temperature of 20C.
As a result of measuring short circuit current values, the average value was 0.517A.
The variation value was 0.086, which was a remarkable effect compared to the average value of 0.452A and the variation value of 0.115- for the previous batteries. Regarding the defective rate, as a result of mass production trial production of 1000 pieces and 60 pieces, the conventional defective rate was 1 to 2%, but with the present invention it is 0. It can be seen that the number has decreased from o1 to o and ooa.

Next, each feature of the present invention will be described.

There are thickeners that can be added to the surface of the positive electrode, but in the above example, a solution with a viscosity of 800 cps was used with an amount of carboxymethyl cellulose added of 1.6% by weight, but the optimum range for the present invention is from 1100 cps to 10,000 cps. The range was appropriate.

If it is less than 100 cps, the adhesive force of the separator on the surface of the positive electrode is weak and mass production in the manufacturing process is impossible.

It was also found that it was difficult to maintain the expected level of short circuit current due to drying of the positive electrode surface.

Furthermore, it was confirmed that if the pressure exceeds 10j5 cpa, it is difficult to drip onto the surface of the positive electrode, resulting in a significant decrease in workability.

Next, regarding the amount of viscous solution added, in the example of the present invention, an amount of 15 μl/cd was added to the surface area of the positive electrode. investigated.

As a result, it was found that as the amount added increases, the leakage resistance deteriorates significantly, which is not desirable. The leakage characteristics were evaluated by placing the battery in an atmosphere with a temperature of 45C1 and a relative temperature of 90%.
The solution was left to stand for a while and then observed under a microscope, and spots or white crystals precipitated were evaluated as leakage.

The results are shown in FIG.

From this result, the amount added to the positive electrode surface is 6 to 50 μl/cdl.
The following was optimal. Note that if the value is less than μQ, the adhesion effect cannot be achieved, making it difficult to mass produce the manufacturing process, and making it impossible to maintain the expected level of short-circuit current.

Regarding the thickener to be added to the alkaline solution, any substance that produces a thickening effect in the alkaline solution can be used; carboxymethyl cellulose was used in the above example, but sodium polyacrylate may also be used. , sodium alginate, methylcellulose.

Thickeners such as polyvinyl alcohol and polyethylene oxide can be used.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the negative electrode part of a button-type alkaline battery according to an embodiment of the present invention, Figure 2 is a cross-sectional view of the positive electrode part, Figure 3 is a cross-sectional view of the completed battery, and Figure 4 shows a viscous solution being used as the positive electrode. Figure 5 is a cross-sectional view showing the configuration of the negative electrode part of a conventional button-type alkaline battery, Figure 6 is a cross-sectional view of a conventional button-type alkaline battery assembled using the same negative electrode part, and Figure 7 The figure is a diagram showing the relationship between the amount of viscous solution added and the leakage rate. 1... Insulating sealing ring, 2... Sealing plate, 3... Negative electrode mixture, 5... Stepped positive electrode case, 6... - Positive electrode mixture, 7... viscous solution, 8... separator. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (3)

[Claims] (1) A positive electrode mixture is pressurized into a positive electrode case with a stepped structure on the side, and a viscous solution made by adding a thickener to an alkaline solution is dropped onto the surface of the positive electrode mixture to attach a separator. A method for manufacturing a button-type alkaline battery, which is characterized by assembling the battery. (2) The viscosity of the alkaline solution added with the thickener is 100
cps or more and 100,000 cps or less
2. Method for manufacturing button-type alkaline batteries as described in Section 1. (3) The amount of viscous solution added to the surface of the positive electrode mixture is
The method for producing a button-type alkaline battery according to claim 1 or 2, wherein the amount is in the range of 6 to 60 μl/cd relative to the surface area of the positive electrode mixture.