JPH1012245A - Manufacture of alkaline dry battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly efficient manufacturing method of a high capacity alkaline dry battery. SOLUTION: After pressurizing molding is performed on a positive electrode mix 2 composed of a manganese dioxide, carbon and a pottasium hydroxide aqueous solution of 39wt.% to 48wt.%, a potassium hydroxide aqueous solution of 30wt.% to 38wt.% is injected into a separator 4 and the positive electrode mix 2, and the concentration of the potassium hydroxide aqueous solution in the whole battery is set to 35wt.% to 45wt.%. Density after pressurizing molding of the positive electrode mix 2 is set not less than 3.4g/cm<3> . By being constituted in this way, the occurrence of a crack and a fragment of the positive electrode mix 2 is reduced, and since impregnating time of an electrolyte can be shortened, a high capacity alkaline dry battery can be manufactured with an excellent yield.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to increasing the capacity and manufacturing efficiency of an alkaline dry battery using a powdered positive electrode mixture.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for higher capacity batteries as power supplies for portable electronic devices and cordless electronic devices. In order to increase the capacity of this battery, it has been conventionally considered to increase the filling amount of the active material of the positive electrode and the negative electrode in view of the volume limitation of the battery. For example, it is common to form a positive electrode mixture into a ring shape without using a binder to increase the density. However, since a binder is not used, it is difficult to secure the moldability and shape stability of the positive electrode mixture, and a high-viscosity electrolytic solution is applied to the densified positive electrode mixture in a short time. It was also difficult to impregnate.

In order to improve the moldability of the positive electrode mixture, a crosslinked type sodium polyacrylate is used as a binder of the positive electrode mixture to prevent cracking and chipping when the positive electrode mixture is formed into a cylindrical shape. There is technology to do. This is described, for example, in the specification of JP-A-57-152677. However, in this method, a part of the limited battery internal volume is used for a binder not involved in the battery reaction, which is not only a problem in increasing the capacity, but also a problem.
This also increases the types of materials used for the battery, and also increases the manufacturing cost.

In addition, the impregnation of the pressure-molded positive electrode mixture with the electrolytic solution has been conventionally performed by adding the electrolytic solution and allowing the mixture to stand for a long time. In order to accelerate the impregnation of the electrolyte, after storing the positive electrode mixture in the positive electrode can, an excessive amount of the electrolyte is injected, and the entire mixture is heated to impregnate the electrolyte with the positive electrode mixture. There are techniques such as removing the electrolyte. Regarding this, for example, Japanese Patent Laid-Open No. 57-1488
No. 79 is mentioned in the specification. However, in this impregnation method, the steps of heating and removing the electrolytic solution are increased, and
There is also a problem that a process for treating an excessive electrolyte is required, and the manufacturing process is complicated.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent cracks and chipping from occurring when a positive electrode mixture is formed into a cylindrical shape, and to apply an electrolyte to the positive electrode mixture in a short time. An object of the present invention is to provide a method of manufacturing an alkaline dry battery which can be impregnated, has a good yield, and has high productivity.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a process for manufacturing an alkaline dry battery having a powdered positive electrode mixture, in which manganese dioxide, carbon and 39% by weight or more and 48% by weight or less are used. After press-molding a positive electrode mixture composed of an aqueous solution of potassium hydroxide, 30% by weight or more and 38% by weight or less of an aqueous potassium hydroxide solution are injected into the separator and the positive electrode mixture, and the concentration of the aqueous potassium hydroxide solution in all the batteries is reduced to 35%. % By weight and 45% by weight or less. Further, the density of the above-mentioned positive electrode mixture after pressure molding was 3.4 g /
The above problem is solved by using a method for manufacturing an alkaline dry battery having a capacity of ³ cm ³ or more.

According to the production method of the present invention, cracking and chipping of the positive electrode mixture can be prevented without adding a binder, and the time for impregnation with the electrolyte can be shortened.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a cylindrical alkaline dry battery as an example of the present invention, and FIG. 2 is a flowchart for explaining electrolyte injection.

[0009] As shown in FIG.
A positive electrode mixture 2 composed of manganese dioxide, carbon and an aqueous solution of potassium hydroxide is placed outside in a cylindrical positive electrode case 1 which also serves as a battery case and has a closed upper end and an open lower end. It is provided separated by a separator 4 made of a non-woven fabric with the gelled negative electrode mixture 3 made of an aqueous solution of potassium oxide, a thickener and the like inside.

A cylindrical outer peripheral surface of the positive electrode case 1 is covered with an outer label 5, and a positive electrode terminal 6 is provided on the upper part of the positive electrode case 1. A sealing member 7 is fitted into the opening of the positive electrode case 1 and seals this opening. The sealing member 7 is made of a plastic material such as nylon or polypropylene. A reinforcing member 8 is provided to reinforce the sealing member 7. -Shaped metal cover is attached. In addition, a brass collector pin 11 is inserted into the negative electrode mixture 3 through a through hole of the sealing member 7 in which the reinforcing member 8 is fitted.

Next, the injection of the electrolyte will be described with reference to FIG. First, manganese dioxide (symbol 20) was converted to 90
Weight% (reference number 23) and carbon (reference number 2).
1) is weighed at 4% by weight (reference numeral 24) and both are dry-mixed (reference numeral 26). On the other hand, 39% to 48% by weight of the electrolytic solution (reference numeral 22) is measured at 6% by weight (reference numeral 25), and the dry-mixed electrolyte is wet-mixed (reference numeral 27).
Next, this mixture is granulated (reference numeral 28), pressed and molded (reference numeral 29) to form a pellet of the positive electrode mixture, and inserted into a positive electrode case (reference numeral 30). Thereafter, a sealant (not shown) is applied, and a separator is inserted inside the pellet (reference numeral 31).
An electrolyte of 8% by weight is injected (reference numeral 32). Illustration and description of subsequent steps are omitted.

EXAMPLES In accordance with the above-described production method, the following types of cylindrical alkaline dry batteries were produced. First, the positive electrode mixtures A to H shown in Table 1 are prepared. The values in the table are the concentrations of the aqueous potassium hydroxide solutions constituting the positive electrode mixtures A to H. This positive electrode mixture was prepared by mixing manganese dioxide, carbon (graphite), and an aqueous potassium hydroxide solution having the concentrations shown in Table 1 at a weight ratio of 90: 4: 6, and was 13.2 mm in outer diameter, 9 mm in inner diameter, 14 mm in height, and 3 in mass. This was a ring having a density of 0.5 g and a density of 3.4 g / cm ³ .

[0013]

[Table 1]

[0014] Each of the above-mentioned molded articles of the positive electrode mixtures A to H was manufactured in 10,000 pieces, and the occurrence rate of cracks and chips in the positive electrode mixture molding step was examined. Table 2 shows the results.

[0015]

[Table 2]

As shown in Table 2, it can be seen that the occurrence of cracks in the molded article of the positive electrode mixture is related to the concentration of the aqueous potassium hydroxide solution. In particular, at a concentration of 38% or less, the incidence of cracks and chips is rapidly increasing.

Further, after three positive electrode mixture molded articles A were filled in the positive electrode case 1 and the separator 4 was inserted, 1 g of an aqueous potassium hydroxide solution having a concentration of a to h as shown in Table 3 was injected. The impregnation time was measured.

[0018]

[Table 3]

During the impregnation time, no liquid pool of the aqueous potassium hydroxide solution was observed at the bottom of the positive electrode case 1 and the positive electrode case 1
The time when the liquid does not spill even if it is reversed is the impregnation time,
Table 4 shows the results.

[0020]

[Table 4]

As shown in Table 4, it can be seen that the impregnation time of the aqueous potassium hydroxide solution with respect to the positive electrode mixture molded product A is related to the concentration of the aqueous potassium hydroxide solution. Especially 3
Above 9%, the impregnation time increases rapidly.

From the above results, by adding an electrolyte comprising an aqueous solution of potassium hydroxide of 39% by weight or more and 48% by weight or less before forming the positive electrode mixture, the occurrence rate of cracking and chipping of the formed body can be greatly reduced In addition, by injecting an electrolyte composed of an aqueous solution of potassium hydroxide of 30% by weight or more and 38% by weight or less in the subsequent step of injecting the electrolyte into the separator and the positive electrode mixture, It can be seen that the impregnation time of the.

[0023]

As is clear from the above description, the production method according to the present invention, that is, at least 39% by weight and 48% by weight
The following electrolytic solution consisting of an aqueous potassium hydroxide solution is added before forming the positive electrode mixture, and in the subsequent step of injecting the electrolytic solution into the separator and the positive electrode mixture, 30% by weight or more and 38% by weight or less of hydroxide are added. By injecting the electrolytic solution composed of the aqueous potassium solution, the occurrence of cracks and chips in the positive electrode mixture molded article is reduced, and the impregnation time of the electrolytic solution is shortened. Therefore, a high-capacity alkaline dry battery can be efficiently manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cylindrical alkaline dry battery which is an example of the present invention.

FIG. 2 is a flowchart for explaining electrolyte injection.

[Description of References] 1 ... Positive electrode case, 2 ... Positive electrode mixture, 3 ... Negative electrode mixture, 4 ... Separator, 5 ... Outer label, 6 ... Positive electrode terminal, 7 ... Sealing member, 8 ... Reinforcement member, 9 ... Spring, 10 ... negative electrode terminal,
11 ... current collecting pin

Claims (2)

[Claims] In a manufacturing process of an alkaline dry battery having a powdered positive electrode mixture, manganese dioxide, carbon, and at least 39% by weight
After press-molding a positive electrode mixture comprising an aqueous solution of potassium hydroxide of not more than 30% by weight, an aqueous solution of potassium hydroxide of not less than 30% by weight and not more than 38% by weight is poured into the separator and the positive electrode mixture. Aqueous solution concentration of 35% by weight or more,
A method for producing an alkaline dry battery, wherein the content is 45% by weight or less. 2. The density of the positive electrode mixture after pressure molding is set to 3.
Characterized by a 4g / cm ³ or more, a manufacturing method of an alkaline dry battery according to claim 1.