JP7790955B2 - Cylindrical battery sealing body and cylindrical battery including said sealing body - Google Patents

Description

The present invention relates to a sealing body for a cylindrical battery and a cylindrical battery including the sealing body.

A typical example of a battery is a cylindrical secondary battery, and nickel-metal hydride batteries are used in a wide range of fields due to their large capacity and clean characteristics. Cylindrical alkaline secondary batteries typically have a sealing body with a safety valve placed at the open end of a cylindrical, bottomed outer can via an insulating gasket. The can is then crimped to close the open end with the sealing body. The mainstream battery manufacturing process involves fitting the sealing body to a gasket and then placing the gasket at the open end of the battery can.

Special Publication No. 2002-502087

The outer periphery of the sealing body is cylindrical, and the inner periphery of the gasket into which the sealing body fits is also cylindrical. With this configuration, if the gasket deforms when the outer can is crimped, the sealing body may come off the gasket, causing a short circuit or poor appearance in the battery.

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

To achieve the above objective, one aspect of the present invention provides a sealing body for a circular battery that is fitted with an insulating gasket to seal the opening of a bottomed outer can of a cylindrical battery. The sealing body has a conductive main body with a flat circular shape, 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 located farther from the center of the main body than the 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 main body, the gasket has an abutment portion that abuts against the outer surface of the main body before the outer can is crimped, and the abutment portion prevents the main body, fitted with the inner circumferential surface, from moving relative to the gasket.

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 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 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 force is applied to the gasket, the sealing body is prevented from moving away from the gasket.

FIG. 1 is a vertical cross-sectional view showing a cylindrical battery according to one embodiment. 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. FIG. 2 is a diagram showing the sealing body and the gasket before they are fitted to each other. FIG. 2 is a schematic diagram showing an exterior can with a sealing body crimped.

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.

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

The outer can 10 contains a roughly cylindrical electrode group 12 together with an alkaline electrolyte (not shown).

The electrode group 12 is composed of a strip-shaped positive electrode plate 16, a negative electrode plate 18, and a separator 20, with the separator 20 sandwiched between the positive electrode plate 16 and the negative electrode plate 18 and wound in a spiral shape. 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.

The positive electrode plate 16 is a strip-shaped electrode filled with a positive electrode active material. 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 hydrophilic groups have been added. The alkaline electrolyte is, for example, a potassium hydroxide solution, a lithium hydroxide solution, a sodium hydroxide solution, or a mixture of these.

One end of the 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 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.

The gas vent hole 26 is normally airtightly closed by the valve body 28. However, if gas is abnormally generated inside the outer can 10 and the internal pressure increases, the valve body 28 is compressed, opening the gas vent hole 26 to the outside, allowing the gas to be released from the outer can 10. In this way, the sealing plate 24, valve body 28, and positive terminal 30 form a safety valve.

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 surface 24A of the sealing plate 24 and the inner 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 short-circuiting between the sealing plate 24, which is connected to the positive terminal 30, and the outer can 10, which is connected to the negative terminal (not shown), and also prevents leakage of electrolyte from the outer can 10.

2. Structures of the Outer Can, Sealing Plate, and Gasket The outer can 10 is a cylindrical shape with an inside diameter _R0 and a central axis X (hereinafter referred to as axis X) that is open at one end, and has a bottom. As shown in Figure 2, a sealing plate receiving portion 10D is formed on the inner circumferential surface 10C, slightly closer to the bottom 10B than the open end 10A. The sealing plate receiving portion 10D protrudes from the inner circumferential surface 10C toward axis X, reducing the inside diameter and extending circumferentially. The sealing plate receiving portion 10D is a portion within the outer can where the sealing plate 24 inserted from the open end 10A of the outer can 10 is placed. The sealing plate receiving portion 10D has an inside diameter _R1 that is smaller than the inside diameter _R0 of the outer can 10 and is also smaller than the diameter of the sealing plate 24, which will be described later.

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 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.

Because the lid plate 24 is engaged with the lid plate receiving portion 10D when inserted into the outer can 10, 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.

The gasket 32 is an insulating, short-axis, bottomed cylinder. When the sealing plate 24 is fitted, the 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 in 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 that is 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 of side wall surface 32E is _R3 , which is the same as the diameter _R3 of outer surface 24C of sealing plate 24. Furthermore, 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.

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.

3. Sealing the outer can After the electrode group 12 is inserted into the opening end 10A of the outer can 10, one end of the current collecting tab 22 is welded to a predetermined position on the positive electrode plate 16, and alkaline electrolyte is poured into the outer can 10.

As shown in FIG. 3 , the sealing plate 24 is fitted into the space defined by the inner peripheral 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 peripheral surface 24A overcomes the inner diameter portion 32G of the inner peripheral surface 32C. Furthermore, the outer peripheral surface 24A engages with the groove 32D, thereby securing the sealing plate 24 to the inner peripheral surface 32C of the gasket 32. At this time, the peripheral edge 24D and its vicinity 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. The sealing plate 24 is then inserted into the exterior can 10 and placed in the sealing plate receiving portion 10D, as shown in Figure 2.

Next, to crimp and secure the sealing plate 24, the edge of the opening end 10A of the outer can 10 is bent in the direction of axis X using a jig, along with the opening end of the cylindrical surface 32A of the gasket 32. When the outer can 10 is crimped, the sealing plate 24 is fitted and secured 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 sealed with the sealing plate 24.

In this way, when the outer can 10 is crimped, the sealing plate 24 does not come off the gasket 32, 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, it is possible to prevent defects in the appearance of the battery 1.

4. Examples As examples, 10,000 AA-size cylindrical batteries having the sealing plate and gasket of the above-described embodiment were manufactured, and as comparative examples, 10,000 AA-size cylindrical batteries having a conventional configuration in which the outer peripheral surface of the sealing plate was cylindrical and the gasket had no grooves were manufactured, and the incidence of detachment of the sealing plate from the gasket when the outer can 10 was crimped was compared.

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.

1 Battery 10 Exterior can 10B Bottom 10A Open end 24 Main body (sealing body)
24B: Inner surface 24C: Outer surface 32: Gasket 32E: Side wall surface 32C: Inner peripheral surface X: Axis

Claims (5)

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. 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. The cylindrical battery sealing body according to claim 2, wherein the side wall portion abuts against the peripheral edge of the outer surface in a band-like manner. The cylindrical battery sealing body according to any one of claims 1 to 3, wherein the main body has a truncated cone shape with the outer surface serving as the bottom surface and the inner surface serving as the top surface. 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.