JPH10302745A - Shield structure of sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shield structure of which an explosion-proof valve composing an explosion safety mechanism, a plastic switch plate, and a sealing cap are assembled with low electric resistance within a small dispersion and with high assembly workability in a sealed lithium secondary battery containing a non-aqueous electrolytic solution. SOLUTION: An explosion-proof valve 18 having elasticity in the vertical direction to the face of a valve main body to release the inner pressure of a battery, a plastic switch plate 20 for preventing over current by shutting off the over current when over current flows, and a sealing cap 22 to be a cathode terminal are stuck and these members are installed in a packing member 24a of an upper face aperture made of an insulating synthetic resin material and at the same time these members are pressurized and pinched by a locking piece 38a formed in the inner circumferential rim part of the upper end of the packing member 24a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed battery using a non-aqueous electrolyte such as a lithium secondary battery, and more particularly, to an explosion-proof safety mechanism for preventing an accident due to overcharging or reverse charging. The present invention relates to a shield structure when mounted on such a sealed battery.

[0002]

2. Description of the Related Art Conventionally, for example, in a lithium secondary battery or the like,
A non-aqueous electrolyte such as an organic electrolyte is used, and discharge is performed by moving lithium ions to the positive electrode and charging is performed by moving lithium ions in the non-aqueous electrolyte. In a battery using a non-aqueous electrolyte such as an organic electrolyte, it is necessary to hermetically shield a battery container (case) so as to prevent leakage of the electrolyte. As the density increases, the danger increases. For example, if the battery is overcharged or short-circuited at the time of charging, the electrolyte may decompose and gas may be generated to increase the internal pressure of the battery. If the battery temperature rises rapidly due to overcharge or short circuit, the battery may be ruptured.

In order to avoid such a situation, for example, as disclosed in Japanese Patent Application Laid-Open No. 8-315798,
A sealed battery provided with an explosion-proof safety mechanism has been proposed. As shown in FIG. 5, a safety valve made of a metal plate that is deformed due to an increase in battery internal pressure is provided at an opening on an upper surface of a battery case 40 in which a non-aqueous electrolyte is loaded. An explosion-proof valve) 42, a polyswitch plate (PTC element) 44 for interrupting the flow of current when an excessive current flows, and an outer peripheral edge of a sealing cap (lid) 46 are overlapped. The explosion-proof safety device is provided in a sealed state by caulking the opening edge of the battery case 40 inward while simultaneously caulking in the direction perpendicular to the surface.

[0004] A secondary battery disclosed in Japanese Patent Application Laid-Open No. 8-124554, which does not have a polyswitch plate (PTC element) but has an explosion-proof safety valve, has a safety valve (explosion-proof valve) and a normally-open pressure-sensitive valve. It is also known to have an explosion-proof safety device including a switch mechanism. This secondary battery is shown in FIG.
As shown in FIG. 1, an explosion-proof diaphragm (explosion-proof valve) 52, a washer 56 having an opening 54 in the center, and a sealer are provided at an opening on the upper surface of a battery case 50 in which a non-aqueous electrolyte is loaded. The outer peripheral edge of the cap 58 is overlapped and mounted via an insulating gasket 60, and the opening edge of the battery case 50 is swaged inward, and at the same time, further swaged in a direction perpendicular to the surface, whereby the explosion-proof safety device is provided. Battery case 5
0 is mounted in a sealed state.

Further, the sealed type battery disclosed in Japanese Patent Application Laid-Open No. 5-34043 is not shown because it has substantially the same configuration as that disclosed in Japanese Patent Application Laid-Open No. 8-315798. (Explosion-proof valve) and the outer edge of the sealing cap are overlapped and attached to the top opening of the battery case via an insulating gasket, and the opening edge of the battery case is swaged inward and at the same time in a direction perpendicular to the surface. It has a configuration that makes it crouch.

Further, a non-aqueous electrolyte battery disclosed in Japanese Patent Application Laid-Open No. 6-163018 has a battery case (outer can) 6 containing a non-aqueous electrolyte, as schematically shown in FIG.
The explosion-proof safety mechanism 70 is provided at the opening on the upper surface of the explosion-proof 0. The explosion-proof safety mechanism 70 is configured such that a flexible thin plate for explosion-proof (corresponding to an explosion-proof valve) 62 and an outer peripheral edge of a sealing cap 64 are overlapped. A flat terminal plate (package plate material) 68 having an opening 66 in the center is applied from below, and the outer peripheral edge of the package plate material 68 is bent to form the flexible thin plate 62 and the sealing cap 64. The explosion-proof safety mechanism 70 is mounted via an insulating gasket 72, and the opening edge of the battery case 60 is crimped inward and, at the same time, crimped in a direction perpendicular to the surface. As a result, it is in a sealed (shielded) state.

[0007]

However, the secondary battery disclosed in the first Japanese Patent Application Laid-Open No. 8-315798 is
The explosion-proof valve and the poly switch board are simply overlapped, mounted in the battery case via a gasket, and the upper edge of the battery case is caulked. Since there is a problem that the safety quality is not stable due to the variation in pressure and the variation in electric resistance, by caulking from the surface direction,
We are trying to solve the problem. In addition, there is a problem that it takes time to align the explosion-proof valve, the polyswitch plate, and the sealing cap, and the workability is poor in caulking the upper edge of the battery case.

Japanese Unexamined Patent Publication Nos. 8-124554 and 5-34043 do not have a polyswitch plate, but are disclosed in the above-mentioned JP-A-8-31579.
There is a problem similar to that disclosed in Japanese Patent Application Laid-Open No. 8-208, and there is a problem that workability of caulking is poor.

Furthermore, the one disclosed in JP-A-6-163018 does not have a polyswitch plate,
In addition to having the problems described in each of the above publications, the explosion-proof valve and the sealing cap are overlapped, the plate material for the package is bent and crimped and integrated, and this is attached to the battery case via a gasket, and then the battery case is further mounted. For example, when the upper end edge is caulked twice, the workability for assembling is further deteriorated because the caulking is performed twice, and the number of parts also increases.

An object of the present invention is to provide an explosion-proof valve, a polyswitch plate, and an explosion-proof safety mechanism in a sealed battery using a non-aqueous electrolyte such as a lithium secondary battery.
An object of the present invention is to provide a sealed structure of a sealed battery in which a battery resistance is reduced and a variation thereof is small when the sealing cap is assembled, and the workability of assembling these members is excellent.

[0011]

To solve this problem, a sealed structure of a sealed battery according to the present invention is provided with an explosion-proof valve for releasing internal pressure of a battery having elasticity in a direction perpendicular to a surface of a valve body. A polyswitch plate for preventing overcurrent, which shuts off when an overcurrent flows, and a sealing cap serving as a positive terminal are overlapped, and these members are placed in a packing container having an upper surface opening made of an insulating synthetic resin material. And attached to
These members are squeezed by locking pieces formed on the inner peripheral edge at the upper end of the packing container, and these are hermetically mounted on the upper opening of the battery case in which the non-aqueous electrolyte is loaded. The gist is to caulk the opening.

According to the sealed structure of a sealed battery having the above-described structure, when the explosion-proof valve, the polyswitch plate, and the sealing cap are overlapped and mounted in the packing container, the positioning of these members is accurately performed. In addition, these members are pressed by the locking pieces formed on the inner peripheral edge of the upper end of the packing container, and there is no variation in battery resistance due to a constant surface pressure. In this state, the battery case is hermetically mounted in the opening on the upper surface of the battery case, so that the assembling work can be performed easily and quickly.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view showing the shield structure of the sealed battery before the caulking step.
The sealed battery 10 is assumed to be a lithium ion secondary battery, and has an outer can (battery case) 12 having an open upper surface.
Although a detailed configuration is not shown, an electrode body 14 including a positive electrode, a negative electrode, and a separator is mounted, and a nonaqueous electrolyte is loaded. As a non-aqueous electrolyte,
For example, an organic solvent in which an electrolyte of 1 N lithium phosphofluoride (LiPF ₆ ) is dissolved in a 1: 1 mixed solvent of polycarbonate (PC) and dimethoxyethane (DME) is used.

A constricted portion 16 bent toward the inside of the case is provided on the peripheral surface of the battery case 12 near the upper opening, and an explosion-proof safety mechanism is provided on the constricted portion 16.
That is, an explosion-proof valve 18 as an internal pressure release mechanism that ruptures due to an increase in battery internal pressure, and a polyswitch plate (PT) that switches off when excessive current flows through the battery.
C element 20 and a cap-shaped sealing cap 22 that protects the inside of the battery and has a function as a current-carrying positive electrode terminal are integrally mounted on a packing member (packing case) 24 made of an insulating resin material. Battery case 12
The battery case 12 is hermetically sealed by being pressed into the upper opening of the battery case by the elastic force of the packing member 24.

FIG. 2 is an exploded sectional view of the sealing cap, explosion-proof valve, polyswitch plate and packing member. As shown in the drawing, the explosion-proof valve 18 has a circular thin film portion 28 for sensing the internal pressure of the battery provided at the center of a disk-shaped valve body 26 corresponding to the inner shape of the battery case 12. A bent portion 30 bent in a direction perpendicular to the surface of the valve body is formed on the outer peripheral edge of the valve body 26, thereby providing elasticity in a direction perpendicular to the surface.

In the packing member 24, a circular opening 34 is formed at the center of a disk-shaped bottom plate 32.
A side wall plate 36 is provided around the outer peripheral edge of the bottom plate 32, and an inward locking piece 38 is provided around the inner peripheral surface of the upper end edge of the side wall plate 36.

When the above-mentioned explosion-proof safety mechanism is mounted on the packing member 24, the explosion-proof valve 18, the polyswitch plate 20 and the sealing cap 22 are overlapped and pushed from the top opening side of the packing member (packing case) 24. . At this time, since the packing member 24 itself is made of an elastic resin material and has elasticity, the upper edge of the opening is pushed out in the radial direction, and the explosion-proof valve 18, the polyswitch plate 20, and the sealing cap 22 are placed inside the packing member 24. It is charged smoothly.

Since the explosion-proof valve 18 is configured to have elasticity in a direction perpendicular to the plane thereof, when the explosion-proof valve 18 is pushed into the packing member 24, the explosion-proof valve 18 The switch plate 20 and the sealing cap 22 are clamped by the bottom plate 32 of the packing member 24 and mounted in a flat state.

When the explosion-proof valve 18, the polyswitch plate 20, and the sealing cap 22 are integrally mounted on the battery case 12, as shown in FIG. Valve 18
Is connected to the positive electrode of the electrode body 14. The explosion-proof safety device thus configured is housed in the opening of the battery case 12 and supported by the constricted portion 16 for positioning.

A packing member 24 integrally provided with the explosion-proof valve 18, the polyswitch plate 20, and the sealing cap 22 is mounted on the upper opening of the battery case 12,
A sealed battery having the cross-sectional structure shown in FIG. 1 is formed. Since the packing member 24 is formed of an insulating elastic resin material, the space between the battery case 12 and the packing member 24 is sealed well.

According to the sealed structure of the sealed battery of the present invention having the above-described structure, the sealing cap 22, the polyswitch plate 20, and the explosion-proof valve 18 are integrated in a state where they are easily positioned in advance by the packing member (packing case) 24. At this time, a state in which the spring property in the direction perpendicular to the surface of the explosion-proof valve 18 is suppressed by the locking piece 38 of the packing member 24 is obtained. Therefore, explosion-proof valve 18, polyswitch plate 2
0, and a reduction in contact resistance between the sealing caps 22 was obtained. Incidentally, the contact resistance is reduced from several hundred mΩ to about 30 to 40 mΩ which is very close to the original resistance value of the polyswitch plate, and the battery performance is improved.

FIG. 3 shows a state in which the explosion-proof safety mechanism is mounted on the battery case 12 as shown in FIG.
FIG. 3 is a cross-sectional view of the lithium secondary battery after a caulking step of an upper opening edge of the lithium secondary battery. The locking piece 38a formed at the upper opening edge of the packing member 24a is
Is pressed by crimping the upper end opening edge inward to compress the packing member 24a from above to maintain a sealed state with the battery case 12.

FIG. 4 shows another configuration applicable to the above-mentioned packing member. This packing member 40 has a circular opening 4 in the center of a disk-shaped bottom plate 42.
4 is formed, and a side wall plate 4 is formed on the outer peripheral edge of the bottom plate 42.
6 are provided around the inner peripheral surface of the side wall plate 46, and three inward locking pieces 48 are provided at equal intervals from each other. When the caulking pressure is strong or the like, a locking portion having such a simplified configuration may be used. When using the packing member 40, the explosion-proof valve 18, the polyswitch plate 20, and the sealing cap 22 are overlapped and pushed from the top opening side of the packing member 40, and the locking piece 48 is used.
As a result, the explosion-proof valve 18, the polyswitch plate 20 and the sealing cap 22 are pressed by the bottom plate 42 of the packing member 40, and are mounted in a flat state.

The present invention is not limited to the above-described embodiment at all, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the polyswitch plate and the explosion-proof valve are separate members, but if a composite material of a synthetic resin layer and a metal material layer is applied, a single member can be provided with the overcurrent prevention and explosion-proof function with a single member. Therefore, the number of parts is further reduced, and a simpler and quicker operation becomes possible.

[0025]

As described above, according to the sealed structure of the sealed battery of the present invention, the explosion-proof valve, the polyswitch plate, and the sealing cap are previously mounted in the insulating packing case. Since the battery case is hermetically mounted, the assembling workability is excellent. At that time, the explosion-proof valve housed in the packing case is provided with elasticity in the direction perpendicular to the surface, and this is suppressed by the locking piece of the packing case to suppress the contact resistance inside the battery. Since the variation is reduced, the electric energy loss is small, which contributes to the increase in capacity and density of this type of closed member.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a state before a caulking step of a shield structure of a sealed battery according to an embodiment of the present invention.

FIG. 2 is an exploded sectional view of the explosion-proof safety mechanism of the sealed battery according to one embodiment of the present invention.

FIG. 3 is a partial cross-sectional view showing a shield structure of a sealed battery as a final product in a state where an upper end opening edge of a battery case is inwardly caulked from the state shown in FIG.

FIG. 4 is a diagram showing a configuration of a packing member according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a shield structure of a conventional sealed battery.

FIG. 6 is a cross-sectional view showing a shield structure of a conventional sealed battery.

FIG. 7 is a sectional view showing a shield structure of a conventional sealed battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Sealed battery 12 Battery case 14 Electrode body 16 Constriction part 18 Explosion-proof valve 20 Poly switch plate 22 Sealing cap 24, 24a Packing member (packing case) 26 Valve main body 28 Thin film part 30 Bent part 32 Bottom plate 34 Opening 36 Side wall plate 38, 38a Locking piece

Claims (1)

[Claims] 1. An explosion-proof valve for releasing internal pressure of a battery having elasticity in a direction perpendicular to a surface of a valve body, a polyswitch plate for preventing an overcurrent from flowing when an overcurrent flows,
The sealing cap serving as a positive electrode terminal is overlapped, and these members are mounted in a packing container having an upper surface opening made of an insulating synthetic resin material, and these members are formed by locking pieces formed on an inner peripheral edge at an upper end of the packing container. A sealed structure for a sealed battery, wherein the member is clamped, and the member is hermetically mounted on an upper surface opening of a battery case in which a non-aqueous electrolyte is loaded, and the upper surface opening of the battery case is caulked. .