Cylindrical battery sealing body and cylindrical battery including said sealing body

Abstract

To provide a cylindrical battery sealing body which does not come off from a gasket when crimped to an outer can.SOLUTION: A cylindrical battery sealing body has a conductive flat body having a circular shape. The body has an inner surface configured to face the bottom of an outer can and an outer surface opposite the inner surface. The peripheral edge of the outer surface is positioned farther from the axis of the outer can to be sealed than the peripheral edge of the inner surface. A gasket has a cylindrical shape with a short axis and is positioned between the outer can and the sealing body. The gasket has a contact portion that contacts the outer surface of the body before crimping of the outer can. The contact portion suppresses the movement of the body fitted to the inner peripheral surface with respect to the gasket.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a sealing body for a cylindrical battery and a cylindrical battery including the sealing body. [Background technology]

[0002] A typical example of a battery is a cylindrical secondary battery, and among these, nickel-metal hydride batteries are used in a wide range of fields due to their large capacity and clean characteristics. Cylindrical alkaline secondary batteries generally have a configuration in which a sealing body equipped with a safety valve is placed at the open end of a cylindrical, bottomed outer can via an insulating gasket, and then the outer can is crimped to close the open end with the sealing body. In the battery manufacturing process, the sealing body is typically fitted with a gasket and then placed together with the gasket at the open end of the battery can. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2002-502087 Summary of the Invention [Problem to be solved by the invention]

[0004] The sealing body has a cylindrical outer circumferential surface, and the gasket into which the sealing body is fitted also has a cylindrical inner circumferential surface. With this configuration, if the gasket is deformed when the outer can is crimped, the sealing body may come off the gasket, resulting in a short circuit or poor appearance of the battery.

[0005] In view of the above problems, an object of the present invention is to provide a sealing body for a cylindrical battery that prevents the sealing body from moving relative to a gasket when the outer can is crimped, and a battery equipped with the sealing body. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a sealing body for a circular battery according to one aspect of the present invention is a sealing body for a cylindrical battery that is fitted with an insulating gasket to seal the opening of a bottomed outer can of a cylindrical battery, and is characterized in that it has a conductive main body that is flat and circular, the main body having an inner surface configured to face the bottom of the outer can and an outer surface opposite the inner surface, the peripheral edge of the outer surface being positioned farther from the center of the main body than the peripheral edge of the inner surface, the gasket having a cylindrical shape with a short axis and being arranged between the outer can and the main body, the gasket having an abutment portion that abuts against the outer surface of the main body in a state before the outer can is crimped, and the abutment portion suppresses movement of the main body that is fitted with the inner circumferential surface relative to the gasket. [Effects of the Invention]

[0007] According to the present invention, when the sealing body is fitted onto the inner peripheral surface of the gasket before being crimped to the outer can, the abutting portion of the gasket abuts against the peripheral edge of the outer surface of the sealing body. This prevents the sealing body from moving relative to the gasket, and the sealing body and the gasket are integrated. Therefore, when the sealing body fitted onto the gasket is placed inside the opening of the outer can and crimped to the outer can, even if a force is applied to the gasket, the sealing body is prevented from moving away from the gasket. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a vertical cross-sectional view showing a cylindrical battery according to one embodiment. [Figure 2] FIG. 2 is a schematic diagram showing an outer can in a state before crimping, in which a sealing body is fitted onto a gasket. [Figure 3] FIG. 2 is a diagram showing the sealing body and the gasket before they are fitted to each other. [Figure 4] FIG. 2 is a schematic diagram showing an exterior can with a sealing body crimped. DETAILED DESCRIPTION OF THE INVENTION

[0009] The sealing body and battery according to the present embodiment will be described below with reference to the accompanying drawings. 1. Battery configuration FIG. 1 shows a nickel-metal hydride secondary battery 1 as a cylindrical battery according to one embodiment of the present invention.

[0010] Battery 1 is an AA-size cylindrical battery, for example, 50.5 mm in height and 14.5 mm in outer diameter, and includes an outer can 10 having a cylindrical shape with one open end and a bottom. Outer can 10 is formed by multi-stage pressing of a nickel-plated steel sheet into a cylindrical shape with one open end 10A and the other closed end 10B. The outer surface of the bottom wall of outer can 10 functions as a conductive negative electrode terminal.

[0011] The exterior can 10 accommodates a substantially cylindrical electrode group 12 together with an alkaline electrolyte (not shown).

[0012] The electrode group 12 is composed of a strip-shaped positive electrode plate 16, a negative electrode plate 18, and a separator 20, and is spirally wound with the separator 20 sandwiched between the positive electrode plate 16 and the negative electrode plate 18. A portion of the negative electrode plate 18 is located at the outermost periphery of the electrode group 12. The outermost periphery of the negative electrode plate 18 comes into contact with the inner surface of the peripheral wall of the outer can 10, thereby electrically connecting the negative electrode plate 18 to the outer can 10.

[0013] The positive electrode plate 16 is a strip-shaped electrode filled with a positive electrode active material. Meanwhile, the negative electrode plate 18 is a strip-shaped electrode made of a hydrogen storage alloy. The separator 20 is made of, for example, a polyolefin fiber nonwoven fabric to which a hydrophilic group has been added. The alkaline electrolyte is, for example, a potassium hydroxide aqueous solution, a lithium hydroxide aqueous solution, a sodium hydroxide aqueous solution, or a mixture thereof.

[0014] One end of a current collecting tab 22 is electrically connected to the positive electrode plate 16 near the open end 10A of the outer can 10, and the other end of the current collecting tab 22 is welded to a circular, conductive sealing plate 24. The sealing plate 24 has a gas vent hole 26 in its center, and a rubber valve body 28 is disposed on the outer surface of the sealing plate 24 so as to cover the gas vent hole 26. The sealing plate 24 is an example of a sealing body or main body. Furthermore, a cylindrical positive electrode terminal 30 with a flange that covers the valve body 28 is fixed to the outer surface of the sealing plate 24, and the positive electrode terminal 30 presses the valve body 28 against the sealing plate 24.

[0015] Gas vent hole 26 is normally airtightly closed by valve element 28. On the other hand, if gas is abnormally generated inside outer can 10 and the internal pressure increases, valve element 28 is compressed, and gas vent hole 26 communicates with the outside, allowing the gas to be released from outer can 10. In this way, sealing plate 24, valve element 28, and positive electrode terminal 30 form a safety valve.

[0016] The sealing plate 24 is located at the opening end 10A of the outer can 10, and a gasket 32 ​​made of an insulating material is sandwiched between the outer peripheral surface 24A of the sealing plate 24 and the inner peripheral surface 10C of the outer can 10. The sealing plate 24 and gasket 32 ​​are fixed to the opening end 10A of the outer can 10 by crimping the portion of the outer can 10 on the opening end 10A side toward the sealing plate 24, thereby closing the opening end 10A. The gasket 32 ​​prevents a short circuit between the sealing plate 24, which is connected to the positive electrode terminal 30, and the outer can 10, which is connected to the negative electrode terminal (not shown), and also prevents leakage of the electrolyte from the outer can 10.

[0017] 2. Structure of outer can, sealing plate and gasket The outer can 10 is a cylindrical shape with a bottom, an inner diameter R0, and a central axis X (hereinafter referred to as axis X) that is open at one end. As shown in Fig. 2, a closure plate receiving portion 10D is formed on the inner circumferential surface 10C at a portion slightly closer to the bottom 10B than the open end 10A. The closure plate receiving portion 10D protrudes from the inner circumferential surface 10C toward axis X, reducing the inner diameter and extending in the circumferential direction. The closure plate receiving portion 10D is a portion within the outer can where the closure plate 24 inserted from the open end 10A of the outer can 10 is placed. The closure plate receiving portion 10D has an inner diameter R1 that is smaller than the inner diameter R0 of the outer can 10 and is also smaller than the diameter of the closure plate 24, which will be described later.

[0018] As shown in Fig. 3, the sealing plate 24 is made of a conductive flat plate with a thickness W. In this embodiment, the sealing plate 24 has a truncated cone shape with its thickness direction parallel to the axis X. The sealing plate 24 has an inner surface 24B that faces the bottom 10B of the outer can 10 when the sealing plate 24 is sealed to the open end 10A of the outer can 10, and an outer surface 24C that is on the opposite side of the thickness direction from the inner surface 24B. Furthermore, the inner surface 24B of the sealing plate 24 forms the top surface of the truncated cone, and the outer surface 24C forms the bottom surface of the truncated cone. In other words, the peripheral edge 24D of the outer surface 24C is located farther away from the axis X than the peripheral edge 24F of the inner surface 24B.

[0019] When the lid plate 24 is inserted into the outer can 10, it is engaged with the lid plate receiving portion 10D, so the diameter R2 of the inner surface 24B is larger than the inner diameter R1 of the lid plate receiving portion 10D. Therefore, the outer peripheral surface 24A connecting the peripheral edge 24D of the outer surface 24C and the peripheral edge 24F of the inner surface 24B is cylindrical and forms a conical surface with a virtual apex on the inner surface 24B side. The outer peripheral surface 24A may be formed by chamfering a circular plate having the same radius as the outer surface 24C.

[0020] The gasket 32 ​​is an insulating, short-axis, bottomed cylinder. When the sealing plate 24 is fitted, its outer diameter R4 is slightly smaller than the inner diameter R0 of the outer can 10. The gasket 32 ​​has a cylindrical surface 32A and a bottom portion 32B that is open at its center and faces the bottom of the outer can 10. An annular groove 32D extending circumferentially is formed on the inner peripheral surface 32C of the cylindrical surface 32A. As shown in FIG. 3 , the groove 32D is composed of a sidewall surface 32E that extends parallel to a direction perpendicular to the axis of the cylindrical surface 32A, and an inclined surface 32F that connects a portion P1 of the sidewall surface 32E farthest from the axis X in the radial direction to an inner edge P2 of the bottom portion 32B. The sidewall surface 32E is an example of an abutment portion. The outer diameter R3 of the sidewall surface 32E is the same as the diameter R3 of the outer surface 24C of the sealing plate 24. Additionally, the axial width W of groove 32D is the same as the thickness W of sealing plate 24. Groove 32D can also be formed by chamfering inner circumferential surface 32C of cylindrical surface 32A radially outward from peripheral edge P2 of bottom surface portion 32B.

[0021] Furthermore, the gasket 32 ​​has an inner diameter portion 32G on the inner circumferential surface 32C, on the opposite side of the bottom surface portion 32B with respect to the groove 32D, that gently protrudes toward the axis X to reduce the inner diameter of the gasket 32 ​​and extends circumferentially. The inner diameter portion 32G forms a temporary seat portion during the process of fitting the sealing plate 24 to the gasket 32. The inner diameter R5 of the inner diameter portion 32G is smaller than the diameter R2 of the inner surface of the sealing plate 24. Note that in other embodiments, the inner diameter portion 32G on the inner circumferential surface of the gasket may be omitted.

[0022] 3. Sealing the outer can The battery 1 is manufactured by inserting the electrode group 12 into the exterior can 10 through the open end 10A, welding one end of the current collecting tab 22 to a predetermined position on the positive electrode plate 16, and pouring alkaline electrolyte into the exterior can 10.

[0023] As shown in FIG. 3 , the sealing plate 24 is fitted into the space defined by the inner circumferential surface 32C of the gasket 32 ​​so that the inner surface 24B contacts the bottom surface 32B of the gasket 32. More specifically, when the sealing plate 24 is pressed toward the bottom surface 32B of the gasket 32, the outer circumferential surface 24A overcomes the inner diameter portion 32G of the inner circumferential surface 32C. Furthermore, the outer circumferential surface 24A engages with the groove 32D, thereby securing the sealing plate 24 to the inner circumferential surface 32C of the gasket 32. At this time, the peripheral edge 24D and the vicinity of the peripheral edge of the outer surface 24C of the sealing plate 24 abut against the side wall surface 32E of the groove 32D of the gasket 32, thereby securing and integrating the sealing plate 24 with the gasket 32. Next, one end of the current collecting tab 22 is connected to the sealing plate 24 via the bottom surface 32B of the gasket 32. Thereafter, the sealing plate 24 is inserted into the exterior can 10 and placed in the sealing plate receiving portion 10D, as shown in FIG.

[0024] Next, to crimp and fix the sealing plate 24, the edge of the opening end 10A of the outer can 10 is bent in the direction of the axis X together with the opening end of the cylindrical surface 32A of the gasket 32 ​​using a jig. When the outer can 10 is crimped, the sealing plate 24 is fitted and fixed to the gasket 32, so even if the gasket 32 ​​is deformed, the outer peripheral surface 23A of the sealing plate 24 will not come out of the groove 32D of the gasket 32. Figure 4 shows the outer can 10 after the outer can 10 has been crimped and the opening end 10A has been sealed with the sealing plate 24.

[0025] In this way, the sealing plate 24 does not come off the gasket 32 ​​when the outer can 10 is crimped, preventing contact between the sealing plate 24 and the outer can 10, i.e., preventing short-circuiting of the electrodes. Furthermore, because the sealing plate 24 is fixed to the outer can 10 at a predetermined location, the appearance of the battery 1 can also be prevented from being poor.

[0026] 4. Working Example As an example, 10,000 AA-size cylindrical batteries having the sealing plate and gasket of the above embodiment were manufactured, and as a comparative example, 10,000 AA-size cylindrical batteries having a conventional configuration in which the outer peripheral surface of the sealing plate is cylindrical and the gasket has no groove were manufactured, and the incidence of the sealing plate coming off the gasket when the outer can 10 was crimped was compared.

[0027] [Table 1]

[0028] 5. Discussion As can be seen from Table 1, in the batteries of the example, no detachment of the sealing plate occurred in the production of 10,000 batteries. On the other hand, in the batteries of the comparative example, in the production of 10,000 batteries, the sealing plate detached or fell off from the gasket in two batteries, an occurrence rate of 0.02%. Considering the current widespread use of batteries as power sources, in the real world, this will lead to a considerable number of defective products. In this way, by engaging and fixing the outer surface of the sealing plate with the gasket, it becomes possible to manufacture higher quality batteries. [Explanation of symbols]

[0029] 1 battery 10 outer can 10B bottom 10A open end 24 Main body (sealing body) 24B Inner surface 24C outer surface 32 Gasket 32E side wall 32C Inner surface X-axis

Claims

1. A cylindrical battery sealing body that is fitted into an insulating gasket and crimps to seal the opening of a bottomed outer can of a cylindrical battery, a conductive body having a flat circular shape; the main body has an inner surface configured to face the bottom of the outer can and an outer surface opposite to the inner surface, and a peripheral edge of the outer surface is located farther from the center of the main body than a peripheral edge of the inner surface; the gasket has a cylindrical shape with a short axis and is disposed between the outer can and the body; The gasket has a contact portion that contacts the outer surface of the main body before the outer can is crimped, and the contact portion suppresses movement of the main body, which is fitted onto the inner circumferential surface, relative to the gasket.

2. the gasket includes an annular groove extending in a circumferential direction on the cylindrical inner peripheral surface, 2. The cylindrical battery sealing body in accordance with claim 1, wherein a side wall portion of said groove extending in a direction perpendicular to the axis abuts against an edge portion of the outer surface of said main body.

3. The cylindrical battery sealing body in accordance with claim 2 , wherein the side wall portion abuts against the peripheral edge of the outer surface in a strip-like manner.

4. 4. The cylindrical battery sealing body according to claim 1, wherein the main body has a truncated cone shape with the outer surface serving as a bottom surface and the inner surface serving as a top surface.

5. an outer can having a cylindrical shape, including an open end portion that is open at one end in the axial direction and a bottom portion that is closed at the other end, and capable of accommodating an electrode group and an electrolyte solution therein; a circular plate-shaped sealing body that seals the open end; an insulating annular gasket disposed at an open end of the outer can between an inner circumferential surface of the outer can and the sealing body; Equipped with the sealing body has an inner surface facing the bottom and an outer surface opposite the inner surface, a peripheral edge portion of the outer surface is located farther away from an axis of the outer can than a peripheral edge portion of the inner surface, The gasket has a contact portion that contacts the outer surface of the sealing body before the outer can is crimped, and the contact portion prevents the sealing body, which is fitted to the inner peripheral surface, from moving relative to the gasket.

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