JP2008004428A - Alkaline battery - Google Patents

Abstract

The present invention provides a highly reliable alkaline dry battery having excellent leakage resistance by suppressing the occurrence of cracks in a connecting portion of a sealing body during caulking.
An alkaline dry battery includes a battery case 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, a negative electrode current collector, and a resin sealing member. The negative electrode terminal plate is provided on the flat portion disposed in the central portion, the flange portion disposed on the peripheral edge portion of the flat portion, and the outer peripheral edge portion of the flange portion, and the cross-section from the folded portion having a V-shaped cross section. The folded portion includes a first portion extending downward from the outer peripheral edge of the flange portion and a second portion extending upwardly inclined from the lower side of the first portion and extending upward. The end portion is bent so as to wrap the upper cylindrical portion of the sealing body, the bent portion is crimped inward, and the folded portion of the negative electrode terminal plate is tightened.
[Selection] Figure 2

Description

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

  In general, an alkaline battery has a negative electrode terminal plate, a negative electrode current collector, and a resin sealing body having a flat part at the center part and a flange part at the peripheral part as an opening part of a battery case that also serves as a positive electrode terminal in which a power generation element is housed. It is sealed by the assembly sealing part which consists of. 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 that connects the portion and the outer peripheral 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. And the opening edge part of the said battery case is bent so that the upper end of the upper cylinder part of the said sealing body may be wrapped, the bending part is crimped inward, and the peripheral part of the said negative electrode terminal plate is clamped.

Conventionally, in order to improve the liquid leakage resistance of alkaline batteries, various studies have been conducted on alkaline batteries having the assembly sealing portion.
For example, in Patent Document 1, in order to suppress stress on the sealing body due to deformation of the flange portion of the peripheral edge of the negative electrode terminal plate during caulking, and to suppress the generation of cracks in the sealing body, It has been proposed to make the collar part thicker than the flat part.
However, even in the configuration of the sealing portion of Patent Document 1, when the upper cylindrical portion of the sealing body is caught by tightening the opening end portion of the battery case during caulking, the connecting portion is pulled to the outer peripheral cylindrical portion side. In addition, stress is applied to the connecting portion of the sealing body, and the connecting portion may be cracked.

Moreover, although it differs from the structure using said assembly sealing part, in patent document 2, in order to improve leakage resistance, the opening part of the battery case which also serves as the positive electrode terminal which accommodated the electric power generation element in the inside is made into the negative electrode terminal plate. In the button-type silver oxide battery sealed with, it has been proposed that the edge of the peripheral edge of the negative electrode terminal plate is folded and compressed, and the folded part is overlapped with the peripheral edge. In this battery, a ring-shaped sealing body is interposed between the opening of the battery case and the peripheral edge of the negative electrode terminal plate, and the peripheral edge of the negative electrode terminal plate is caulked inwardly. Is tightened. As described above, in the negative electrode terminal plate, the folded portion is overlapped with the peripheral portion, whereby the strength of the peripheral portion of the negative electrode terminal plate is increased and the sealing performance can be improved.
However, in an assembly sealing part like patent document 1, the detailed examination regarding the shape of a negative electrode terminal board is still not performed for the purpose of prevention of generation | occurrence | production of the crack in the connection part of a sealing body.
JP 2001-313010 A Japanese Patent Laid-Open No. 5-3024

  Therefore, in order to solve the above-described conventional problems, the present invention relieves stress applied to the connecting portion of the sealing body during caulking, suppresses the occurrence of cracks in the connecting portion during long-term storage, and has excellent leakage resistance. Another object of the present invention is to provide a highly reliable alkaline battery.

  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. 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 downward from the inner peripheral edge of the horizontal portion, and the negative terminal plate is formed at the central portion. Provided flat part, of the flat part A flange portion provided at an edge portion and an outer peripheral edge portion of the flange portion, and a cross-section is formed of a V-shaped folded portion, and the folded portion extends downward from the outer peripheral edge portion of the flange portion. And a second portion extending upwardly inclined downward from the lower side of the first portion, and bent so that the opening end portion of the battery case wraps the upper end of the upper cylindrical portion of the sealing body The bent portion is caulked inward to fasten the folded portion of the negative terminal plate.

In the negative electrode terminal plate, an angle formed by a direction perpendicular to the flat portion and the second portion is preferably 1 to 20 °.
The height H of the second portion, the height H1 of the first portion, and the height H2 of the negative electrode terminal plate preferably satisfy the relational expression: 1 / 2H1 <H <H2.

  According to the present invention, the stress applied to the connecting portion of the sealing body during caulking is alleviated, and the occurrence of cracks in the connecting portion during long-term storage can be prevented. Therefore, a highly reliable alkali with excellent leakage resistance A dry battery is obtained.

An embodiment of the alkaline dry battery of the present invention will be described with reference to FIGS.
FIG. 1 is a front view of a cross section of a part of an AA alkaline battery (LR6) 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. On the stepped portion 1a, a horizontal portion 14b of the sealing body 5 described later is disposed. The assembly sealing portion 12 includes a negative electrode terminal plate 7, a negative electrode current collector 6, and a resin sealing body 5.

  2 and 3, the negative electrode terminal plate 7 has a disk-shaped flat portion 8b at the center, an annular flange 8a at the peripheral edge of the flat portion 8b, and a cross section at the outer peripheral edge of the flange 8a. It has a character-shaped folded portion 9. The folded portion 9 includes an annular first portion 9a that extends downward from the outer peripheral edge of the flange portion 8a, and an annular second portion 9b that extends upward from the lower side of the first portion 9a. Consists of.

  The first portion 9a is inclined in the direction of the arrow Q (that is, the inner direction of the alkaline battery) with respect to the axis P (the direction perpendicular to the flat portion 8b) indicating the longitudinal direction of the alkaline battery in FIG. , May be substantially parallel to the axis P. On the other hand, the second portion 9b needs to be inclined with respect to the axis P in the direction of the arrow R (that is, the outer direction of the alkaline battery). The degree of inclination (inclination angle) can be selected as appropriate.

The thickness t of the negative electrode terminal plate 7 is, for example, 0.2 to 0.4 mm, and preferably 0.2 mm.
The diameter of the flat portion 8b is, for example, 7 to 9 mm, and preferably 8.7 mm. The level difference between the flat portion 8b and the flange portion 8a is, for example, 1.0 to 2.0 mm, and preferably 1.7 mm. The width | variety of the collar part 8a is 0.4-0.8 mm, for example, Preferably it is 0.6 mm.
The flat portion 8 b of the negative electrode terminal plate 7 is electrically connected to the head 6 a of the negative electrode current collector 6, and the negative electrode current collector 6 is inserted in the center of the gelled negative electrode 3.

As shown in FIG. 2, the sealing body 5 is interposed between the central cylindrical portion 13 having the through hole 13 a into which the negative electrode current collector 6 is inserted, the folded portion of the negative 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.
In the sealing body 5, the thickness of the outer periphery cylinder part 14 is 0.5-0.8 mm, for example, Preferably it is 0.6 mm. The thickness of the connection part 15 is 0.6-1.2 mm, for example, Preferably it is 0.8 mm. The thickness of the thin portion 15a is, for example, 0.15 to 0.40 mm, and preferably 0.25 mm.
The height of the center cylinder part 13 is 5.0-10.0 mm, for example, Preferably it is 6.0 mm. The outer diameter of the center cylinder part 13 is 4-6 mm, for example, Preferably it is 4 mm. The inner diameter of the central cylinder portion 13 is, for example, 1 to 2 mm, and preferably 1.375 mm.

  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 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 folded portion 9 of the negative terminal plate 7 is tightened onto the horizontal portion 14b. It has been. The outer surface of the battery case 1 is covered with an exterior label 10.

Since the outermost peripheral portion (second portion 9b of the folded portion) of the negative electrode terminal plate 7 is inclined upward from the lower side of the first portion 9a and extends upward, the portion of the sealing body 5 is sealed when sealed. Since the upper tube portion 14a is hard to be inserted, the upper tube portion 14a can be prevented from being caught during the caulking process, and the stress applied to the connecting portion 15 of the sealing body 5 can be reduced. Therefore, the occurrence of cracks in the connecting portion 15 due to this stress can be suppressed, and an alkaline dry battery having excellent leakage resistance even during long-term storage can be obtained.
Since the upper cylindrical portion 14a is difficult to be inserted, it is preferable that the end surface (cut end) on the outermost peripheral side of the second portion 9b faces the outside.

  Here, FIG. 4 is an enlarged cross-sectional view of the Y portion (the folded portion 9 of the negative electrode terminal plate 7) in FIG. As shown in FIG. 4, the angle θ formed by the axis P (the direction perpendicular to the flat portion 8b) indicating the longitudinal direction of the alkaline battery and the second portion 9b is 1 to 20 °. preferable. If the angle θ is less than 1 °, the connecting portion 15 is likely to crack. If the angle θ exceeds 20 °, leakage (sealing creep) from between the battery case 1 and the upper cylindrical portion 14a due to insufficient tightening of the opening end of the battery case 1 is likely to occur.

  The height H of the second portion 9b, the height H1 of the first portion 9a, and the height H2 of the negative electrode terminal plate 7 (the height from the flat portion 8b to the lowest portion of the folded portion 8) are related. It is preferable to satisfy the formula: 1 / 2H1 <H <H2. When H is 1 / 2H1 or less, sealing creep tends to occur. When H is H2 or more, the space for storing the power generation element is reduced, and the battery capacity is reduced.

  The maximum width W of the folded portion 9 is, for example, 0.4 to 1.5 mm, and preferably 0.5 mm. The height H1 of the first portion 9a is, for example, 0.6 to 1.2 mm, and preferably 0.8 mm. The height H of the second portion 9b is, for example, 0.3 to 2.0 mm, and preferably 0.8 mm. A height H2 from the flat part 8b of the negative electrode terminal plate 7 to the lowermost part of the folded part 8 is, for example, 1.5 to 3.0 mm, and preferably 2.1 mm.

  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 (step portion) between the flange portion 8a and the flat portion 8b. 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. The leakage due to the occurrence of cracks in the connecting portion 15 is caused by the electrolyte solution leaking from the cracks flowing out through the holes.

Examples of the present invention will be described in detail below, but the present invention is not limited to these examples.
<< Examples 1-8 and Comparative Example 1 >>
(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 then pressed into a hollow cylindrical shape 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. FIG. 2 shows an enlarged cross-sectional view of the portion X (sealed 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 disposed 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 6a of the negative electrode current collector 6 and the flat portion 8b of the negative electrode terminal plate 7, and the negative electrode current collector 6 is connected to the nylon sealing body 5 (thickness of the outer peripheral cylinder portion 14: 0). 6 mm, the thickness of the connecting portion 15: 0.8 mm, and the thickness of the thin portion 15 a is 0.2 mm).
And the opening edge part of the battery case 1 is bent, the upper end of the upper cylinder part 14 a of the sealing body 5 is wrapped and caulked inward, and the folded part around the periphery of the negative electrode terminal plate 7 is connected to the battery case 1 via the outer cylinder part 14. The opening portion of the battery case 1 was sealed by tightening with the opening end portion. The outer surface of the battery case 1 was covered with the exterior label 10.

During the manufacture of the alkaline battery, the negative electrode terminal plate 5 (thickness t: 0.4 mm, diameter: 11.5 mm, first portion 8a height H1: 0.8 mm, and negative electrode terminal plate 7 Height H2: 2.0 mm) was produced. At this time, the angle θ formed by the first portion 9a and the second portion 9b and the height H dimension of the second portion 9b were changed as shown in Table 1.
And the alkaline dry battery was produced using these negative electrode terminal boards 7, respectively.

<< Comparative Example 2 >>
Instead of the negative electrode terminal plate 7, a negative electrode terminal plate having no folded portion, that is, a negative electrode terminal plate 17 (thickness: 0) having a flat portion 18b (diameter: 8.0 mm) at the central portion and a flange portion 18a at the peripheral portion. An alkaline dry battery was produced in the same manner as in Example 1 except that .4 mm, diameter: 11.5 mm, and height (step between the flange portion 18a and the flat portion 18b): 2.0 mm were used.

[Evaluation]
100 each of the batteries obtained above were produced, and the leakage resistance of the batteries was evaluated by the following method.
About each battery, after preserve | saving for 12 hours in the environment of temperature-20 degreeC, the heat cycle test which repeats the process preserve | saved for 12 hours in the environment of temperature 80 degreeC was done. Then, when 6 months and 8 months have passed, the battery is disassembled, a crack is generated in the connecting portion of the sealing body, and the liquid leaks from the hole provided between the flange portion and the flat portion of the negative electrode terminal plate. Investigate whether or not. In addition, it was examined whether liquid leakage (sealing creep) occurred between the sealing body and the battery case.
The evaluation results are shown in Table 2.

  In the batteries of Comparative Examples 1 and 2, there were batteries that leaked due to the occurrence of cracks in the connecting portion of the sealing body. On the other hand, in Examples 1-8, there was no crack in the connection part of a sealing body in any battery, and it was able to suppress the liquid leakage by generation | occurrence | production of a crack. In particular, in Examples 1 to 5, in any of the batteries, there was no leakage from between the battery case and the sealing body, and excellent leakage resistance was obtained.

  The alkaline dry battery of the present invention has excellent leakage resistance, and is suitably used as a power source 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 negative electrode terminal plate 7 of FIG. It is the longitudinal cross-sectional view which expanded the folding | turning part (Y part) in FIG. It is a longitudinal cross-sectional view of the negative electrode terminal board in the alkaline dry battery of the conventional comparative example 2.

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 8a Eave part 8b Flat part 9 Folding part 9a 1st part 9b 2nd part 10 Exterior label 11 Negative electrode terminal board DESCRIPTION OF SYMBOLS 12 Assembly sealing part 13 Central cylinder part 13a Through-hole 14 Outer periphery cylinder part 14a Upper cylinder part 14b Horizontal part 14c Lower cylinder part 15 Connection part 15a Thin part

Claims (3)

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,
The negative electrode terminal plate includes a flat portion provided at a center portion, a flange portion provided at a peripheral edge portion of the flat portion, and an outer peripheral edge portion of the flange portion, and a cross-section including a V-shaped folded portion. ,
The folded portion is composed of a first portion extending downward from the outer peripheral edge of the flange portion and a second portion extending upwardly inclined downward from the lower side of the first portion,
An alkali characterized in that an opening end portion of the battery case is bent so as to wrap an upper end of an upper cylindrical portion of the sealing body, and the bent portion is caulked inward to fasten a folded portion of the negative electrode terminal plate. Dry cell.   2. The alkaline dry battery according to claim 1, wherein in the negative electrode terminal plate, an angle formed between a direction perpendicular to the flat portion and the second portion is 1 to 20 °. The height H of the second portion, the height H1 of the first portion, and a height H2 of the negative electrode terminal plate satisfy a relational expression: 1 / 2H1 <H <H2. Alkaline battery.

Images