JPH065273A - Manufacture of safety device and its sealing plate of cylindrical battery - Google Patents

Abstract

PURPOSE:To improve the reliability and the safety by cutting off the continuity perfectly regardless of the variation of temperature, as well as letting the pressure escape to the outer side, when the internal pressure rises in a cylindrical battery. CONSTITUTION:A positive electrode terminal plate 14 has a projecting cutting edge 14b at the lower side, which is opposed to a diaphragm 22. And a current breaker 24a is projecting-formed integrally, and blade-form rings 28 are laminated through a conductive plate 24 which consists of a metallic sheet and a sheet 26 for insulation and adhesion concurrently. And when the gas pressure inside the battery rises, the current breaker 24a is denatured to the positive electrode terminal 14 side, its bulb-form outer periphery is pushed against a cutting edge 28a and cut off, and the continuity inside the battery is cut off, so as to remove the cause of the temperature rise. Furthermore, when the internal pressure rises, the diaphragm 22 is also pushed against the cutting edge 14a at the positive electrode terminal 14 side to generate a broken hole, so as to let the gas escape to the outer side, and thereby, a breakage of the battery can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a cylindrical battery and a method of manufacturing a sealing plate for the battery, which allows the pressure to escape to the outside when the internal pressure of the battery rises and completely shuts off the conduction inside the battery. Regarding

[0002]

2. Description of the Related Art Generally, a cylindrical lithium battery has a high possibility of bursting due to an internal short circuit due to misuse or the like due to its higher electric energy density than other batteries. Therefore, in this type of battery, an explosion-proof safety device is provided by a combination of a terminal plate and a sealing plate. This safety device is a combination of a mechanism that allows the internal pressure caused by gas generation to escape to the outside and a mechanism that increases the resistance value by increasing the temperature and extremely limits the conduction inside the battery. Conventionally, the structure shown in FIG. 4 is generally adopted. Has been done.

In the figure, a sealing plate 2 provided on the lower surface of a terminal plate 1 having a gas vent hole 1a formed therein has a valve hole formed in the center of a lower surface of a ring-shaped positive temperature coefficient resistance element (PTC element) 3. Clamped ring 4 and diaphragm 5
Further, the positive electrode plate 7 connected to the positive electrode lead plate 6a led out from the power generation element 6 is provided. Then, a cutting blade 1b protruding downward from the gas vent hole 1a by cutting and raising.
Are opposed to the diaphragm 5, and the terminal plate 1 and the sealing plate 2 are fixed to the opening of the battery case 9 while being held by the inner periphery of the sealing gasket 8.

In this structure, when gas is generated due to an internal short circuit in the case 9 and the internal pressure rises rapidly, the diaphragm 5 bulges upward and the cutting edge 1b pierces it. Thus, the gas inside is released to the outside through the gas vent hole 1a.

Further, the resistance of the PTC element 3 connected to the terminal plate 1 increases extremely due to the temperature rise, so that the conduction between the terminal plate 1 and the positive electrode plate 7 is extremely limited, and an external short circuit occurs. When an overcurrent due to the above conditions flows, the current is narrowed down.

[0006]

However, in actuality, when an excessive current flows in the PTC element 3, the resistance increases remarkably as described above to limit the current, but a minute current continues to flow, so that the battery is It is not possible to sharply lower the temperature. Further, since the PTC element 3 is an element that operates in response to temperature, it may not be able to cope with a battery abnormality that does not change with temperature, or it may malfunction depending on the temperature of the environment in which the battery is used. It had the disadvantage of poor security and safety.

The present invention solves the above problems, and its purpose is to completely shut off the conduction when the internal pressure rises, regardless of the temperature thereof, and further improve the reliability and safety. Another object of the present invention is to provide a method of manufacturing the safety device for the cylindrical battery and the sealing plate thereof.

[0008]

In order to achieve the above object, the present invention provides a valve between a terminal plate having a gas vent hole in the center and a terminal plate disposed below the terminal plate. In a tubular battery provided with a sealing plate that constitutes a chamber, the sealing plate is a ring with a valve hole opened in the center, and is arranged below the ring, and holds the ring.
A conductive plate made of a thin metal plate integrally formed with a current breaker for connecting a lead plate that bulges in the shape of a bulb in the center of the lower surface, and is laminated on the lower surface of the conductive plate and faces the periphery of the current breaker. And a blade ring having a cutting edge formed around a central opening.

Further, the sealing plate is laminated on the lower surface of the ring, and is sandwiched integrally with the conductive plate together with the ring so as to always close the valve hole and to provide a cutout projecting from the gas vent hole. It may be configured to have a diaphragm facing the blade.

The blade ring may be made of a metal press-molded body and may be laminated on the lower surface of the conductive plate via an insulating ring, or may be made of an insulating material such as ceramic. Good.

In the sealing plate, a recess having a substantially cylindrical hollow portion is formed in the center of a disk-shaped metal thin plate, and a blade ring is formed on the back surface of the recess forming surface of the metal thin plate with an adhesive. The cutting edge formed on the blade-shaped ring is opposed to the convex portion that appears symmetrically on the back surface of the concave portion, the convex portion is placed on a rigid member, and the hollow portion of the concave portion is formed. By inserting a pipe filled with an elastic material such as silicone rubber or polyurethane rubber, and pressing the elastic material to push it out from the open end of the pipe into the hollow portion of the recess, the hollow portion is moved to the bottom of the recess. Is the widest, and the inner diameter of the thin metal plate is reduced as it gets closer to the surface of the thin metal plate, and it is manufactured by expanding into a bulb shape.

[0012]

According to the present invention having the above structure, when the gas pressure inside the battery increases, the current breaker is displaced toward the terminal plate side in response to the increase in the internal pressure, and the bulbous outer periphery is pressed against the cutting edge, By disconnecting, the conduction inside the battery is completely cut off. When the internal pressure further rises, the diaphragm is also pressed against the cutting edge on the terminal plate side to generate a rupture hole, and the gas is released to the outside.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view showing a portion of a safety device for a cylindrical lithium battery according to the present invention.

In the figure, reference numeral 10 denotes a cylindrical battery case in which an electric power generating element 12 is housed inside and an upper opening is provided.
Is a positive electrode terminal plate fixed to the opening of the case 10 through a sealing gasket 16, and 18 is a lower part of the terminal plate 14, and together with the terminal plate 14 in a state of being integrally contacted with a peripheral edge thereof, It is a sealing plate held inside the sealing gasket 16, and the sealing plate 18 and the terminal plate 14 constitute a safety device.

A gas vent hole 14a is opened in the center and the periphery of the terminal plate 14 in the same manner as in the conventional case, and a cutting blade 14b is provided on the lower surface of the terminal plate 14 by cutting and raising, and is provided in the center of the sealing plate 18. Facing each other.

The sealing plate 18 has a ring 20 having a valve hole 20a formed in the center thereof, and a diaphragm 22 laminated on the lower surface of the ring 20 to constantly close the valve hole 20a and face the cutting edge 14b. On the lower surface of the diaphragm 22, the ring 20 and the diaphragm 22 are held, and a conductive plate 24 made of a thin metal plate integrally formed with a current breaker 24a that bulges in a bulb shape in the center of the lower surface, A blade ring 28 made of a metal press-molded body is laminated on the lower surface of the conductive plate 24 via a sheet 26 that also serves as an insulator and an adhesive.

As the diaphragm 22, a laminated film in which a thin metal plate and a plastic film are laminated and which easily expands due to an increase in internal pressure is used.

A positive electrode lead plate 12a led to the upper part of the power generating element 12 is connected to the lower surface of the current breaker 24a, and a bent portion of a peripheral edge 24b of the conductive plate 24 is a peripheral flange of the positive electrode terminal plate 14. It is joined to the part.

An opening is formed in the center of the blade ring 28, and a cutting edge 28a having a downwardly directed cutting edge is integrally formed on the inner peripheral edge of the opening, and the bulb shape of the current breaker 24a is formed. Opposite the periphery of the bulge.

As described above, in this embodiment, the diaphragm 22 for releasing the internal pressure and the current breaker 24a for interrupting the current are integrally joined, but it is not always necessary to integrally provide both. .

The method of molding the sealing plate 18 of the present embodiment described above is shown in FIGS. 2 (a) to 2 (e). First, as shown in (a), the peripheral edge 24b of the conductive plate 24 is raised, and the blade ring 28 is bonded via the sheet 26 (hot melt) in a state where the convex portion 24a 'is formed in the current breaker 24a. Then, the cutting edge 28a is opposed to the convex portion 24a '.

Next, as shown in (b), the convex portion 24a '
Is placed on the stopper 30, a pipe 34 filled with an elastic material 32 such as silicone rubber or polyurethane rubber is inserted into the convex portion 24a ', and the elastic material 32 is extruded as shown in FIG. The lower part of 24a 'expands like a bulb to form a current breaker 24a.

After that, as shown in (d), the diaphragm 22 and the ring 20 are installed on the inner circumference of the upper portion of the conductive plate 24, and the peripheral edge 24b is caulked inside. Complete.

The operation of the safety device having the above configuration is as follows. First, when the gas pressure inside the battery rises for some reason, the current breaker 24a is displaced toward the terminal plate 14 side in response to the rise in the internal pressure, and the outer periphery of the bulbous bulge portion is the cutting edge of the blade ring 28. It is pressed against 28a and a part of it breaks. When the internal pressure further rises after that, the diaphragm 22 tries to bulge toward the terminal plate 14 side, but the current breaker 24a is also further deformed and eventually cuts off, completely interrupting the conduction between the lead plate 10a and the terminal plate 14. . After that, the diaphragm 24 swells and the terminal board 14
It is pressed against the side cutting edge 14b to form a rupture hole, which allows gas to escape to the outside and avoids rupture in advance.

At this time, since the internal circuit of the battery is completely cut off, the temperature rise of the battery is quickly stopped irrespective of the operating environment temperature, and the dangerous situation of ignition is completely avoided.

Next, the performance of the cylindrical lithium battery corresponding to the AA type SUM-3 type equipped with the safety device of the present invention shown in FIG. 1 and the battery of the conventional structure shown in FIG. 4 were compared by a short-circuit test. However, the results shown in FIG. 3 were obtained.

The figure shows the passage of time since the abnormality occurred (horizontal axis).
And changes in current and temperature (vertical axis). Focusing on the conventional example, the current value relatively sharply decreases and then becomes flat in the second quartile after a short circuit. After that, the current value decreases again in the quartile, and then the current continues to flow at a constant current value. This is due to the characteristics of the PTC element. on the other hand,
Battery temperature rises relatively rapidly up to about 4 minutes after short circuit,
After that, it becomes constant at about 100 ° C. The reason why the temperature becomes constant at such a high temperature is that the PTC element cannot completely block the current.

On the other hand, in the battery having the safety device of the present invention, both the current and the temperature show the same behavior as before until about 3 minutes after the short circuit, but the current value is 3.5 minutes after the short circuit. It becomes 0 at that point. This clearly indicates that the circuit has been completely cut off by the current breaker. On the other hand, the battery temperature rises slightly after the circuit is cut off and then gradually decreases to the normal temperature, which indicates that the temperature is effectively lowered by the circuit break.

When the above short circuit test was carried out for 200 pieces each of the conventional structure and the structure of the present invention, 8 pieces of the conventional structure ignited, whereas the number of ignition of the structure of the present invention was 0. It is clear that there is a significant difference in performance in terms of safety.

Further, in the above embodiment, the blade ring 28 is made of a metal press-molded body and laminated and adhered to the conductive plate 24 via the sheet 26 that serves both insulation and adhesion. The blade ring 28 may be made of an insulating material such as ceramic to increase the height.

[0031]

As described above in detail with reference to the embodiments, according to the safety device for a cylindrical battery and the method for manufacturing the sealing plate according to the present invention, when the gas pressure inside the battery increases, the internal pressure rises accordingly. The current breaker is displaced to the terminal board side, and its bulbous outer periphery is pressed against the cutting blade and cut,
Since the conduction inside the battery is completely cut off, the factor of temperature rise can be quickly eliminated.

When the internal pressure further rises, the diaphragm is also pressed against the cutting edge on the side of the terminal plate to form a rupture hole, which allows gas to escape to the outside, so that rupture of the battery due to an increase in internal pressure can be prevented. Safety is improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing a portion of a safety device for a cylindrical lithium battery according to the present invention.

FIG. 2 is a cross-sectional view illustrating a procedure for manufacturing a sealing plate in the safety device.

FIG. 3 is a graph comparing the elapsed time and changes in current value and temperature during a short-circuit test between the conventional product and the product of the present invention.

FIG. 4 is a cross-sectional view of a main part of a cylindrical lithium battery including a conventional safety device.

[Explanation of symbols]

 10 Battery Case 12 Power Generation Element 12a Positive Electrode Lead Plate 14 Positive Electrode Terminal Plate 14a Gas Venting Hole 14b Cutting Edge 16 Sealing Gasket 18 Sealing Plate 20 Ring 22 Diaphragm 24 Conductive Plate 24a Current Breaker 24b Peripheral Part (of Conductive Plate 24) 26 Adhesion / Insulation Combined sheet 28 Blade ring 28a Cutting blade

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiro Harada 5-311, Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (72) Hidenori Nagura 5-36-11 Shinbashi, Minato-ku, Tokyo Fuji Electrochemical Co., Ltd.

Claims (5)

[Claims] 1. A tubular battery comprising a terminal plate having a gas vent hole in the center thereof and a sealing plate disposed below the terminal plate and forming a valve chamber between the terminal plate and the terminal plate, The sealing plate includes: a ring having a valve hole opened in the center; disposed below the ring and holding the ring,
A conductive plate made of a thin metal plate integrally formed with a current breaker for connecting a lead plate, which bulges in the shape of a bulb in the center of the lower surface; and is laminated on the lower surface of the conductive plate and faces the periphery of the current breaker. A tubular battery safety device, comprising: a blade ring having a cutting edge formed around a central opening. 2. The sealing plate is laminated on the lower surface of the ring, and is sandwiched integrally with the conductive plate together with the ring so as to always close the valve hole and to provide a cutout protruding from the gas vent hole. The tubular battery safety device according to claim 1, further comprising a diaphragm facing the blade. 3. The cylindrical battery according to claim 1, wherein the blade ring is made of a metal press-molded body and is laminated on the lower surface of the conductive plate via an insulating ring. Safety device. 4. The blade-shaped ring is made of an insulating material such as ceramics.
The safety device for a cylindrical battery according to. 5. A disc-shaped metal thin plate is formed with a recess having a substantially cylindrical hollow portion in the center thereof, and a blade ring is adhered to the back surface of the recess-formed surface of the metal thin plate with an adhesive, The cutting edge formed on the blade ring is made to face the convex portion that appears symmetrically on the back surface of the concave portion, the convex portion is placed on the rigid member, and the hollow portion of the concave portion is made of silicone rubber or polyurethane rubber. By inserting a pipe filled with an elastic material such as, and pressing the elastic material into the hollow portion of the recess from the open end of the pipe, the hollow portion has the widest bottom portion, A method for manufacturing a sealing plate for a cylindrical battery, wherein the sealing plate spreads in a bulb shape whose inner diameter decreases as it approaches the surface of the thin metal plate.