JPH10334878A - Alkaline battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability against impact, namely, suppress the movement of a bottom paper against impacts by specifying inclined angles of the thickness of the bottom paper, in the bottom end of the inside of a cylindrical separator and a rising part surrounding the bottom paper to the bottom face respectively. SOLUTION: A hollow cylindrical positive electrode mix 4 is inserted into a metal positive electrode case 3 so as to be in pressure contact with the metal positive electrode case 3. After that, a separator 5 is inserted into the positive electrode mix which is wound around into a bottom cylindrical shape, so as to be in pressure contact therewith, Second, a hooped bottom paper is cut into a prescribed shape, an insertion punch and a die are set, and then the cut bottom paper 1 is inserted and in pressure contact with the bottom end of the inside face of the cylindrical separator 5, so as to be formed into the bottom paper 1. The bottom paper of this alkaline battery is set so as to have the thickness of 0.2 mm to 0.5 mm and an inclined angle of the surrounding rising part of the bottom paper of 50 deg. to 70 deg.. This alkaline battery thus causes no internal short circuit and is superior in impact resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkaline battery and, more particularly, to an improvement in a base paper thereof.

[0002]

2. Description of the Related Art In recent years, the demand for cordless portable devices, such as notebook personal computers and PHSs, which require a large amount of current and is compatible with power supplies as well as rechargeable batteries has tended to increase sharply. With this increase in demand, there has been a demand for improvement in the discharge performance of alkaline batteries, and in particular, improvement in high-rate characteristics corresponding to strong discharge use.

[0003] A conventional alkaline battery will be described below. In FIG. 2, reference numeral 11 denotes a circular bottom paper. 2 is an exterior label, 3 is a positive electrode case, 4 is a positive electrode mixture, 5 is a separator, 6 is a gelled negative electrode, 7 is a current collector, 8 is a resin sealing body,
9 is an insulating washer and 10 is a bottom plate.

Conventionally, the base paper 11 has been laminated with a non-electroconductive alkali-resistant coating in order to prevent a short circuit between the positive electrode case 3 and the gelled negative electrode 6. Also,
When the bottom paper 11 is inserted into the inner surface of the separator using an insertion punch and a die, the conventional method of scraping and inserting the bottom paper one by one requires the bottom paper to have a thickness of about 0.5 mm, and has a round shape. The bottom paper is squeezed into a cup and inserted.

[0005]

When considering the improvement of the reaction efficiency by reducing the thickness of the base paper in order to improve the discharge performance, an impact due to continuous vibration when transporting or carrying an alkaline battery or a strong impact due to dropping is considered. On the other hand, the bottom paper is also easy to move along with the movement of the gelled negative electrode inside the alkaline battery.
That is, there is a risk of causing an internal short circuit.

As means for preventing the internal short-circuit, means for injecting a hot-melt substance into the lower end of the separator instead of the bottom paper (JP-A-58-154177) is implemented. Does not cause an internal short circuit, but there is a drawback that the injection of the heat-meltable substance reduces the effective volume of the gelled negative electrode, and the manufacturing process becomes complicated, leading to an increase in cost.

The present invention solves the above problems,
It is an object of the present invention to provide an alkaline battery in which the reliability against impact, that is, the movement of the bottom paper due to the impact is suppressed.

[0008]

In order to achieve this object, an alkaline battery according to the present invention has a bottom paper having a thickness of 0.2 mm to 0.5 mm and an inclination angle of the rising portion around the bottom paper with respect to the bottom surface of 50 °. It has a configuration of up to 70 °.

Further, the bottom paper is inserted into the battery by using an insertion punch having a convex portion for forming the peripheral rising portion with an inclination angle of 50 ° to 70 ° with respect to the bottom surface and a die corresponding thereto. This is a manufacturing method in which the lower part of the inner surface of the separator is pressed against the inner surface.

[0010] As described above, by relaxing the inclination angle of the rising portion around the bottom paper from a right angle, the rising portion around the bottom paper presses the inner side surface of the separator, thereby increasing the “tensile” and reducing the thickness of the bottom paper. However, the bottom paper becomes difficult to move due to the continuous vibration and the impact due to the drop, and the separation between the positive electrode case and the gelled negative electrode is maintained, and no internal short circuit occurs.
In other words, if the inclination angle is larger than 70 °, the bottom shape is formed by the insertion punch and the die, and there is a risk that the rising corner of the bottom sheet may be cut off when inserted into the battery. Conversely, the inclination angle is larger than 50 °. If it is too small, the "tension" that presses on the inner surface of the separator will be too strong, and when the base paper is inserted, the separator will be partially pushed down together with the base paper, causing the separator height to drop, causing the gelled negative electrode to overflow and causing a short circuit inside the positive electrode mixture. is there.

[0011]

FIG. 1A is a half sectional view of a cylindrical alkaline battery LR6 used in an embodiment of the present invention.
FIG. 1B is an enlarged cross-sectional view of the lower part of FIG. Except for the bottom paper of No. 1, all are the same as conventional alkaline batteries.

The production method of the present invention will be described below with reference to FIGS. First, the metal positive electrode case 3
A positive electrode mixture 4 having a hollow cylindrical shape is inserted into the positive electrode mixture 4 and pressed into contact with the metal positive electrode case 3 (FIG. 3A). Thereafter, the separator 5 is wound into a cylindrical shape with a bottom, and the pressed positive electrode mixture is pressed. Step of inserting into the mixture (FIG. 3 (b), supplying the hoop-shaped bottom paper 14 and cutting it into a fixed shape, setting the insertion punch 12 and die 13 (FIG. 3 (c)), and then cutting. The bottom paper 1 of the present invention is formed in the step of inserting and pressing the bottom paper 1 to the lower end of the inner surface of the cylindrical separator 5 with the insertion punch 12 (FIG. 3D).

At this time, as shown in FIG. 4, the tip of the insertion punch 12 used has a tapered shape with respect to the bottom surface, and the inclination angle of the rising portion around the bottom paper with respect to the bottom surface is adjusted. .

In this embodiment, the bottom paper is made of vinylon and has a thickness of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 m.
m, and the above six types of bottom papers are inclined to the bottom surface of the rising portion around the bottom paper at 40, 50, 60, 70, and 80 using convex insertion punches and dies of various taper. The cylindrical separator was inserted into the lower part of the inner surface of the cylindrical separator and pressed into contact with the lower part to form a total of 30 types. Thereafter, an alkaline battery was produced by a usual production method.

Here, as shown in Table 1, the degree of press-contact of the bottom paper with the side surface of the separator, that is, "tensile strength" was examined for the thickness of the bottom paper and the inclination angle of the rising portion of the bottom paper.
Further, as shown in (Table 2), impact resistance (internal short-circuit occurrence rate) was examined. Here, as a substitute characteristic representing "tensile strength", a value obtained by measuring an insertion pressure when a base paper is inserted into a separator using a load cell is shown.

[0016] The impact resistance is defined as +
A test to determine the presence or absence of an internal short-circuit by measuring the voltage after applying the vibration 60 times a minute at an amplitude of 50 mm for 1 hour with the pole up, and measuring the voltage before and after the vibration 100 batteries were tested by the test method, and the number of batteries having a voltage fluctuation of 10 mV or more before and after vibration was regarded as defective.

[0017]

[Table 1]

[0018]

[Table 2]

As can be seen from Table 1, when the inclination angle of the rising portion around the bottom paper is small and the thickness of the bottom paper is large, the insertion pressure "tensile strength" becomes large. As can be seen from Table 2, when the inclination angle of the peripheral rising portion of the bottom paper is smaller than 50 °, the gelled negative electrode overflows and an internal short circuit occurs. This is probably because the insertion pressure “tensile strength” was large and the separator was pushed down when the bottom paper was inserted. Conversely, the inclination angle is 70 °
If it is larger than this, the clearance between the bottom paper insertion punch and the die and the thickness of the bottom paper becomes small, and the bottom paper breaks during insertion, causing an internal short circuit.

In the case of the bottom paper having a thickness of 0.1 mm, the insertion pressure "tensile strength" is small, so that the bottom paper moves due to vibration, and the gelled negative electrode turns under the bottom paper to cause an internal short circuit. . Conversely, with a base paper with a thickness of 0.6 mm, the above-mentioned “tensile strength” is strong and the separator can be easily pushed down when the base paper is inserted,
There was a tendency for the internal short circuit occurrence rate to increase.

On the other hand, from 0.2 mm to 0.2 mm according to the present invention.
Alkaline batteries with a thickness of 5 mm and a base paper with a rising angle of 50 ° to 70 ° at the rising edge of the base paper are free from internal short-circuits, are excellent in impact resistance, and are more cost-effective due to thinner base paper. When considering the surface and the reaction efficiency, the effect is more obtained by using a bottom paper having a thickness of 0.2 mm to 0.4 mm and an inclination angle of 50 ° to 70 °.

In this embodiment, the square base paper is employed. However, the same effect can be obtained with a circular or other shape, but the square shape is superior in terms of productivity and production cost. ing.

In this embodiment, vinylon is used as the material of the bottom paper. However, similar effects can be obtained by using other synthetic resins, kraft paper, or the like.

In this embodiment, a cylindrical separator having a bottom is used as the cylindrical separator. However, a similar effect can be obtained with a simple cylindrical separator without a bottom.

[0025]

As described above, according to the present invention, there is provided a bottom paper having a shape in which the thickness of the bottom paper is 0.2 mm to 0.5 mm and the inclination angle of the rising portion around the bottom paper is 50 ° to 70 °. Thereby, an excellent alkaline battery capable of improving impact resistance can be realized.

[Brief description of the drawings]

FIG. 1A is a half cross-sectional view of an AA alkaline battery LR6 according to an embodiment of the present invention. FIG.

FIG. 2 is a half sectional view of a conventional AA alkaline battery LR6.

FIG. 3 is a process schematic diagram showing the production method of the present invention.

FIG. 4 is a side view of the bottom paper insertion punch of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bottom paper (square shape) 2 Exterior label 3 Positive electrode case 4 Positive electrode mixture 5 Separator 6 Gelled negative electrode 7 Current collector 8 Resin sealing body 9 Insulation washer 10 Bottom plate 11 Bottom paper (circular shape) 12 Insert punch 13 Die 14 Hoop shape Bottom paper

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takayuki Aoi 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A metal positive electrode case, a hollow cylindrical positive electrode mixture inscribed therein, a cylindrical separator inscribed in the positive electrode mixture, a negative electrode active material and an alkali contained in the separator. Having a bottom paper at the lower end of the inner surface of the separator, a peripheral rising portion thereof is inclined, and the lower part of the inner surface of the separator is pressed against and closed, and the bottom paper has a thickness. 0.2 to 0.5 mm, and the inclination angle of the rising portion around the bottom paper with respect to the bottom surface is 50 mm.
° to 70 ° alkaline batteries. 2. The base paper having a thickness of 0.2 mm to 0.4 mm
2. The alkaline battery according to claim 1, wherein the distance is in mm. 3. The alkaline battery according to claim 1, wherein said cylindrical separator has a bottom. 4. The alkaline battery according to claim 1, wherein said bottom paper has a square shape. 5. A step of inserting and pressing a hollow cylindrical positive electrode mixture into a metal positive electrode case, and a step of winding a separator into a cylindrical shape and inserting it into the pressed positive electrode mixture, and Inserting and press-contacting the bottom paper cut into a shape at the lower end of the inner surface of the cylindrical separator, wherein the inclination angle of the bottom paper with respect to the bottom surface of the peripheral rising portion with respect to the bottom surface is 50 ° or more.
A method for manufacturing an alkaline battery, comprising: inserting into a battery using an insertion punch having a convex portion formed into a shape of 70 ° and a die corresponding thereto, and pressing a lower portion of an inner surface of the separator into pressure. . 6. The method according to claim 5, wherein the bottom paper is supplied in a hoop shape.