JP2007173042A - Alkaline battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable alkaline battery having good liquid leakage resistance. <P>SOLUTION: A sealing body for this alkaline battery is provided with an outer circumference cylinder part, which is constructed of an upper cylinder part, a horizontal part, and a lower cylinder part, an inner circumference cylinder part having a through-hole for inserting a negative collector, and a connection part connecting the outer circumference cylinder part and the inner circumference cylinder part together. A thickness ratio of the horizontal part to the upper cylinder part is 0.65 or less, and in the upper cylinder part, a ratio of its thickness to its outside diameter is 0.015 or more. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an alkaline battery, and more particularly to a sealing body of an assembly sealing portion that closes an opening of a battery case.

Conventionally, in order to improve the leakage resistance of alkaline batteries, various studies have been made on the sealing portion.
For example, in Patent Document 1, in a configuration in which an opening of a battery case is sealed using a resin sealing body and a negative electrode terminal plate, an outer peripheral cylindrical portion of the sealing body is interposed between the battery case and the terminal plate, and the battery case The opening end portion of the sealing body is bent inward together with the upper end of the outer peripheral cylindrical portion, and the compression state of the outer peripheral cylindrical portion of the sealing body when the outer peripheral cylindrical portion of the sealing body is tightened to the peripheral edge portion of the terminal plate and caulked is proposed Yes.

  Moreover, in patent document 2, in order to relieve the stress applied to the sealing body after the caulking process in order to prevent the crack from occurring in the sealing body due to the stress generated by the caulking process during long-term storage, together with the battery case It has been proposed that a portion that receives the lower surface of the peripheral portion of the negative electrode terminal plate and a portion that suppresses the upper surface of the peripheral portion of the negative electrode terminal plate are separately provided in the outer peripheral cylindrical portion of the sealing body that is caulked. That is, it has been proposed to provide a structure in which the upper end of the outer peripheral cylindrical portion of the sealing body is directed inward in advance by separately providing a portion for suppressing the upper surface of the peripheral portion of the negative electrode terminal plate.

However, in the case of using a sealing body in which the upper end of the outer peripheral cylindrical portion bends inward during caulking, as in Patent Document 1, the purpose is to prevent the occurrence of cracks during long-term storage by relaxation of stress caused by caulking. However, the examination of the form of the sealed body has not been sufficiently conducted.
Moreover, in patent document 2, since a sealing body was divided | segmented and used, there existed a problem that part cost and the number of battery assembly processes increased, and manufacturing cost increased.
JP 2001-28395 A Japanese Patent Laid-Open No. 2003-051295

  Accordingly, the present invention provides a highly reliable alkaline battery that suppresses stress applied to the sealing body during caulking and has excellent liquid leakage resistance even during long-term storage in order to solve the above-described conventional problems. Objective.

The alkaline battery of the present invention includes a battery case that also serves as a positive electrode terminal in which a power generation element is housed, and an assembly sealing portion that closes an opening of the battery case, and the assembly sealing portion includes a negative electrode terminal plate and the negative electrode terminal. A negative electrode current collector electrically connected to the plate, and a resin sealing body, the sealing body having a through hole into which the negative electrode current collector is inserted, a peripheral edge portion of the negative electrode terminal plate, An outer peripheral cylindrical portion interposed between the open end portion of the battery case and a connecting portion that connects the central cylindrical portion and the outer peripheral cylindrical portion, and the outer peripheral cylindrical portion receives a peripheral portion of the negative electrode terminal plate. An annular horizontal portion, an upper cylindrical portion that rises upward from the outer peripheral edge of the horizontal portion, and a lower cylindrical portion that extends downwardly from the inner peripheral edge of the horizontal portion. Wrap the top end of the upper cylinder of the sealing body Folded as writing, a peripheral portion of the negative electrode terminal plate is swaged its bent portion or inwardly an alkaline dry battery tightened onto the horizontal portion,
The ratio of the thickness of the upper cylinder part to the thickness of the horizontal part is 0.65 or less, and the ratio of the thickness of the upper cylinder part to the outer diameter of the upper cylinder part is 0.015 or more. Features.

The connecting part preferably has a thin part.
The sealing body is preferably made of a polyamide resin.
The polyamide-based resin is preferably 6,12-nylon.

  According to the present invention, since the sealing body has sufficient strength and can reduce the stress applied to the sealing body after being swaged, it prevents cracking of the sealing body during long-term storage and has liquid leakage resistance. And a highly reliable alkaline dry battery.

An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a front view with a cross section of a part of an alkaline battery as an embodiment of the present invention.
A hollow cylindrical positive electrode mixture 2 is inscribed in a bottomed cylindrical battery case 1 that also serves as a positive electrode terminal. A gelled negative electrode 3 is disposed in the hollow portion of the positive electrode mixture 2 via a bottomed cylindrical separator 4. The positive electrode mixture 2, the separator 4, and the gelled negative electrode 3 contain an alkaline electrolyte. For the separator 4, for example, a nonwoven fabric mainly composed of polyvinyl alcohol fiber and rayon fiber is used.

For the positive electrode mixture 2, for example, a mixture of at least one of manganese dioxide powder and nickel oxyhydroxide powder as a positive electrode active material, graphite powder as a conductive agent, and a potassium hydroxide aqueous solution as an alkaline electrolyte is used.
For the gelled negative electrode 3, for example, a mixture of zinc powder as a negative electrode active material, sodium polyacrylate as a gelling agent, and an aqueous potassium hydroxide solution as an alkaline electrolyte is used.

Here, FIG. 2 is an enlarged cross-sectional view of a portion X (a sealing portion of an alkaline battery) in FIG.
In the battery case 1, a power generation element such as the positive electrode mixture 2 is accommodated, and then a step 1 a is provided in the vicinity of the opening. The opening of the battery case 1 is sealed by the assembly sealing part 12. A horizontal portion 14b described later is disposed on the step portion 1a. The assembly sealing portion 12 includes a negative electrode terminal plate 7 having a peripheral edge flange portion 7a and a central flat portion 7b, a negative electrode current collector 6 electrically connected to the flat portion 7b of the negative electrode terminal plate 7, and a resin seal It is composed of a body 5. A negative electrode current collector 6 is inserted in the center of the gelled negative electrode 3.

  As shown in FIG. 3, the sealing body 5 is interposed between the central cylinder portion 13 having a through hole 13 a into which the negative electrode current collector 6 is inserted, the peripheral portion of the negative electrode terminal plate 7, and the opening end portion of the battery case 1. The outer peripheral cylinder part 14 is connected, and the central cylinder part 13 and the outer peripheral cylinder part 14 are connected to each other, and the connection part 15 has an annular thin part 15a that functions as a safety valve. The outer peripheral cylindrical portion 14 is inclined downward from the annular horizontal portion 14b that receives the peripheral portion of the negative electrode terminal plate 7, the upper cylindrical portion 14a that rises upward from the outer peripheral portion of the horizontal portion 14b, and the inner peripheral portion of the horizontal portion 14b. It consists of the lower cylinder part 14c extended. The opening end portion of the battery case 1 is bent so as to wrap around the upper end of the upper cylindrical portion 14a of the sealing body 5, the bent portion is caulked inward, and the peripheral edge portion of the negative electrode terminal plate 7 is tightened onto the horizontal portion 14b. ing. The outer surface of the battery case 1 is covered with an exterior label 10.

  In the sealing body 5 shown in FIG. 3, the ratio of the thickness A of the upper cylindrical portion 14a to the thickness B of the horizontal portion 14b (hereinafter referred to as A / B) is 0.65 or less and The ratio of the thickness A of the upper cylindrical portion 14a to the outer diameter C of the cylindrical portion 14a (hereinafter referred to as A / C) is 0.015 or more.

When the sealing body 5 satisfies the above-described configuration, stress can be prevented from concentrating on the connecting portion 15 between the horizontal portion 14b and the inner peripheral cylindrical portion 13, particularly the thin-walled portion 15a, during caulking. Thus, even during long-term storage, the generation of cracks in the sealing body 5 due to stress can be suppressed, and an alkaline dry battery having excellent leakage resistance can be obtained. Further, unlike the conventional case, it is not necessary to divide the outer peripheral cylindrical portion 14, so that the component cost and the number of battery assembly steps increase, and the manufacturing cost does not increase.
When A / B exceeds 0.65, the stress applied to the connecting portion 15 of the sealing body 5 increases, and cracks are likely to occur during long-term storage. On the other hand, when A / C is less than 0.015, the strength of the upper cylindrical portion 14a of the sealing body 5 is lowered, and the upper cylindrical portion 14a may be deformed when the sealing body 5 is stored. It is preferable that A / B is 0.6 or less and A / C is 0.02 or more in that the above effect can be obtained more remarkably.

In order to ensure the strength of the sealing body 5, the thickness A of the upper cylindrical portion 14a and the thickness B of the horizontal portion 14b are preferably 0.2 mm or more.
More preferably, the thickness A of the upper cylindrical portion 14a is 0.3 to 0.8 mm, and the thickness B of the horizontal portion 14b is 0.5 to 1.5 mm. If the thickness A of the upper cylindrical portion 14a exceeds 0.8 mm, a large force is required during caulking, and the stress applied to the connecting portion 15 increases accordingly, and the sealing body 5 is likely to crack. On the other hand, when the thickness B of the horizontal portion 14b exceeds 1.5 mm, the assembly sealing portion 12 becomes thick, and the filling volume of the active material decreases.
The outer diameter C of the upper cylindrical portion 14a is a minimum of 6 mm of the LR8D425 size and a maximum of 33 mm of the single 1 type (LR20) size.
When the thickness A and outer diameter C of the upper cylindrical portion 14a and the thickness B of the horizontal portion 14b are within the above ranges, for example, A / B is 0.13 to 0.65, and A / C is 0. .015 to 0.13.

For the sealing body 5, for example, polypropylene, polyethylene, or polyamide-based resin such as 6-nylon, 6,6-nylon, or 6,12-nylon is used.
Among these, it is preferable to use a polyamide-based resin. When the polyamide-based resin is immersed in an alkaline electrolyte, hydrolysis of the resin proceeds and the resin becomes brittle. This property is more effective for suppressing the generation of cracks by reducing the stress generated by caulking. Among polyamide-based resins, 6,12-nylon is more preferable in that it has a small water absorption and excellent dimensional stability.

  In the upper cylindrical portion 14a of the sealing body 5, the ratio of the height h2 shown in FIG. 2 after being bent by caulking to the height h1 shown in FIG. 3 before caulking (hereinafter referred to as compression ratio (h2 / h1)) Is preferably 0.6 to 0.9. When the compression ratio exceeds 0.9, compression by caulking is insufficient and airtightness may not be sufficiently obtained. When the compression ratio is less than 0.6, the reaction force (stress) to the connecting portion or the like in the sealing body increases, and cracks in the sealing body are likely to occur.

  For example, an aqueous potassium hydroxide solution is used as the alkaline electrolyte. The concentration of the aqueous potassium hydroxide solution is preferably 32 to 40% by weight. When the concentration of the potassium hydroxide aqueous solution exceeds 40% by weight, the absolute amount of water contributing to the battery reaction is reduced, and the battery performance is deteriorated. On the other hand, when the concentration of the potassium hydroxide aqueous solution is less than 32% by weight, hydrolysis of the resin constituting the sealing body proceeds and cracks are likely to occur.

  The negative electrode terminal plate 7 has, for example, a hole (not shown) for releasing the gas in the battery to the outside at the boundary portion between the flange portion 7a and the flat portion 7b. When the battery internal pressure rises abnormally, the thin portion 15a of the sealing body 5 is broken, and gas can be released to the outside from the above holes.

Examples of the present invention will be described in detail below, but the present invention is not limited to these examples.
<< Examples 1 to 6 and Comparative Examples 1 to 4 >>
(1) Preparation of positive electrode mixture Manganese dioxide powder and graphite powder were mixed at a weight ratio of 90:10. And this mixture and 40 weight% potassium hydroxide aqueous solution as alkaline electrolyte were mixed by the weight ratio of 100: 3, and after fully stirring, it compression-molded to flake shape. Next, the flaky positive electrode mixture was pulverized into granules, classified by a sieve, and pressed into a hollow cylinder to obtain a pellet-shaped positive electrode mixture.

(2) Preparation of gelled negative electrode Sodium polyacrylate as a gelling agent, 40 wt% potassium hydroxide aqueous solution as an alkaline electrolyte, and zinc powder as a negative electrode active material were mixed at a weight ratio of 1:33:66. Thus, a gelled negative electrode was obtained.

(3) Assembly of cylindrical alkaline battery An AA alkaline battery (LR6) having the structure shown in FIG. 1 was produced by the following procedure. FIG. 1 is a front view with a cross section of a part of a cylindrical alkaline battery. Further, FIG. 2 shows an enlarged cross-sectional view of an X portion (sealing portion) in FIG.
Two of the positive electrode mixtures 2 obtained as described above were inserted into the battery case 1, and the positive electrode mixture 2 was remolded with a pressure jig and adhered to the inner wall of the battery case 1. A bottomed cylindrical separator 4 was placed in the center of the positive electrode mixture 2 in close contact with the inner wall of the battery case 1. A predetermined amount of 40% by weight potassium hydroxide aqueous solution was injected into the separator 4 as an alkaline electrolyte. After a predetermined time had elapsed, the gelled negative electrode 3 obtained above was filled in the separator 4. In addition, the separator 4 used the nonwoven fabric which mixed and mixed mainly the polyvinyl alcohol fiber and the rayon fiber.

A groove portion is formed in the vicinity of the opening portion of the battery case 1 to form a step portion 1a, and the assembly sealing portion 12 is formed in the opening portion of the battery case 1 so as to receive the horizontal portion 14b of the assembly sealing portion 12 on the step portion 1a. Was installed. At this time, a part of the negative electrode current collector 6 was inserted into the on-gel negative electrode 3. The assembly sealing portion 12 is electrically welded to the head portion 6 a of the negative electrode current collector 6 and the flat portion 7 b of the negative electrode terminal plate 7, and the negative electrode current collector 6 is inserted into the through hole 13 a of the central cylindrical portion 13 of the nylon sealing body 5. Obtained by insertion.
And the opening edge part of the battery case 1 is bent, the upper end of the upper cylinder part 14a of the sealing body 5 is wrapped and caulked inward, and the peripheral part of the negative electrode terminal plate 7 is connected to the battery case 1 via the outer cylinder part 14. The opening of the battery case 1 was sealed by tightening with the opening end. The outer surface of the battery case 1 was covered with the exterior label 10.

The sealing body 5 made of 6,6-nylon was obtained by injection molding. At this time, the dimension of the thickness A of the upper cylindrical portion 14a is variously changed, the ratio (A / B) of the thickness A of the upper cylindrical portion 14a to the thickness B of the horizontal portion 14b, and the outer side of the upper cylindrical portion 14a. Sealing bodies 5 having different ratios (A / C) of the thickness A of the upper cylindrical portion 14a to the diameter C were produced. In addition, the thickness B of the horizontal part 14b was 0.8 mm, and the outer diameter C of the upper cylinder part 14a was 13.1 mm.
Moreover, the compression ratio of the upper cylinder part 14a at this time was 0.75.
And the alkaline dry battery was produced using these sealing bodies 5, respectively.

[Evaluation]
(1) Evaluation of battery leakage resistance Prepare 60 batteries obtained above, store them in a high temperature environment of 80 ° C for 4 months, and examine the number of batteries that leaked after storage. It was. In addition, the presence or absence of liquid leakage was judged visually.

(2) Leaving test of sealing bodies Each of the sealing bodies obtained as described above was prepared in 1000 pieces, the sealing bodies were boxed and allowed to stand at room temperature for 1 week, and the number of deformed sealing bodies was examined. At this time, the sealing body was passed through a gauge having an inner diameter of 13.4 mm, and it was determined that the sealing body in which a portion where the outer diameter C of the upper cylindrical portion caught by the gauge exceeded 0.3 mm was present was deformed.
The evaluation results are shown in Table 1.

  In Comparative Examples 1 and 2, since the dimension of the thickness of the outer peripheral cylindrical portion was too large, the stress applied to the sealing body after caulking was increased, and a crack occurred in the sealing body during the storage period, resulting in leakage. A battery was found. Moreover, in the sealing bodies of Comparative Examples 3 and 4, since the outer peripheral cylindrical portion was too thin, the strength was reduced, and a sealing body in which the outer peripheral cylindrical portion was deformed after being packaged and stored in a container was observed.

  In Examples 1-6, since the intensity | strength of a sealing body is enough and a shape is maintained, after packing into a container, none of the sealing bodies deform | transformed. In addition, since the stress applied to the connecting portion of the sealing body after the caulking process was reduced and no crack was generated during the storage period, none of the batteries leaked. Thus, in the batteries of Examples 1 to 6, excellent leakage resistance was obtained.

  The alkaline dry battery of the present invention has high reliability and is suitably used for power supplies for electronic devices and portable devices.

It is the front view which made some alkaline dry batteries in one embodiment of the present invention a section. It is the longitudinal cross-sectional view which expanded the sealing part (X part) in FIG. It is a longitudinal cross-sectional view of the sealing body used for the alkaline dry battery in one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery case 2 Positive electrode mixture 3 Gel-like negative electrode 4 Separator 5 Sealing body 6 Negative electrode current collection 7 Negative electrode terminal board 10 Exterior label 12 Assembly sealing part 13 Central cylinder part 13a Through-hole 14 Outer cylinder part 14a Upper cylinder part 14b Horizontal part 14c Lower cylinder part 15 Connection part 15a Thin part

Claims (4)

A battery case that also serves as a positive electrode terminal that houses a power generation element therein, and an assembly sealing portion that closes an opening of the battery case,
The assembly sealing portion comprises a negative electrode terminal plate, a negative electrode current collector electrically connected to the negative electrode terminal plate, and a resin sealing body,
The sealing body includes a central cylindrical portion having a through-hole into which the negative electrode current collector is inserted, an outer peripheral cylindrical portion interposed between a peripheral edge portion of the negative electrode terminal plate and an opening end portion of the battery case, and the central cylindrical portion A connecting portion for connecting the portion and the outer cylindrical portion,
The outer peripheral cylindrical portion extends from the annular horizontal portion that receives the peripheral edge of the negative electrode terminal plate, the upper cylindrical portion that rises upward from the outer peripheral edge of the horizontal portion, and the inclined downward from the inner peripheral edge of the horizontal portion. It consists of a lower cylinder part,
An alkali in which the opening end of the battery case is bent so as to wrap around the upper end of the upper cylindrical portion of the sealing body, and the bent portion is crimped inward to tighten the peripheral edge of the negative terminal plate onto the horizontal portion A dry cell,
The ratio of the thickness of the upper cylinder part to the thickness of the horizontal part is 0.65 or less,
The alkaline dry battery, wherein a ratio of a thickness of the upper cylindrical portion to an outer diameter of the upper cylindrical portion is 0.015 or more.   The alkaline battery according to claim 1, wherein the connecting portion has a thin portion.   The alkaline dry battery according to claim 1, wherein the sealing body is made of a polyamide-based resin. The alkaline dry battery according to claim 3, wherein the polyamide-based resin is 6,12-nylon.

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