JPS60198051A - Sealed battery - Google Patents

Abstract

PURPOSE:To prevent any explosion of a sealed battery which might be caused by an increase in the internal pressure by installing a doughnut-like shape- memorizing alloy having a blade with a sharp edge between the sealing plate and the generation element so that the thin section of the sealing plate is broken by the blade when the temperature of the battery increases. CONSTITUTION:The opening of a negative case 11 containing a lithium plate 12, a separator 13 and a carbon electrode 14 is sealed with a sealing plate 17 having a thin section 19 by fusing the plate 17 to the case 11 through a fusion section 16. A doughnut-like shape-memorizing alloy 20 composed of 50% Ti and 50% Ni and having a blade 21 with a sharp edge located corresponding to the thin section 19 is installed between the sealing plate 17 and the generation element and the outer periphery of the alloy 20 is fused to the case 11, thereby constituting a sealed battery. Because of the above structure, when the temperature of the battery increases, the alloy 20 deforms into a flat shape breaking the thin section 19 by the blade 21 thereby resulting in gas exhaustion. Accordingly it is possible to prevent any increase in the internal pressure of the battery.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sealed battery used as a power source for small electronic devices related to electronics.

Conventional Structure and Its Problems A sealed nickel-cadmium battery with a built-in safety valve device according to the first example is shown in FIG. In the figure, 1 is a metal case that also serves as a negative electrode terminal, 2 is a cadmium negative electrode, 3 is a separator, 4 is a nickel positive electrode, 5 is a thin metal plate, 6 is a cutting edge portion made by cutting out a part of the sealing plate 9 and bending it inward. 7 is a positive electrode lead plate, 8 is an opening, 9 is a sealing plate that also serves as a positive electrode terminal, and 10 is a sealing gas hole.

In the case of this battery, when the internal pressure of the battery rises, the thin metal plate 5 is pushed up and broken by the cutting edge 6, and the gas is released into the opening 8.
is discharged to the outside.

The thin metal plate that functions as a safety mechanism is fixed by caulking the sealing plate 9, which also serves as a positive terminal, with its peripheral edge in close contact with a sealing gasket.

This battery uses a resin gasket in the sealing part, so when it is used at high or low temperatures, the gasket softens or shrinks, changing the mechanical caulking state. There is a drawback that if the liquid creep phenomenon occurs and is severe, it may lead to liquid leakage.

In particular, when a sealed battery using an alkaline electrolyte is stored under high temperature and high humidity conditions, it is extremely difficult to completely prevent leakage from the seal.

If a hole is created by cutting a part of the sealing plate as described above, if the product is stored under high temperature and high humidity conditions, moisture will enter the interior through the opening and water droplets will adhere to the bottom of the sealing plate and the thin metal plate. .

On the other hand, when using the crimp sealing method described above, when an organic electrolyte is applied, depending on the type of electrolyte used, the resin gasket may be eroded and the electrolyte may creep from the sealing part, resulting in significant deterioration of battery characteristics. There are drawbacks.

In order to improve these problems, it is necessary to weld and seal the battery case with a non-metallic terminal. In addition, it is particularly important in practical terms that when an abnormality occurs in the battery, a safety valve device is activated to prevent accidents such as explosion.

Purpose of the Invention The present invention maintains the airtightness of the battery at all times.In the event that an abnormality occurs in the battery, a safety valve device is activated to prevent the battery from exploding. The purpose is to provide batteries.

Structure of the Invention The present invention relates to a safety valve device for a completely sealed battery in which a metal container and a sealing plate of the battery are sealed by laser welding. The battery is characterized by a completely sealed battery with a built-in safety valve device in which the peripheral edge of a shape memory alloy with a sharp cutting blade fixed thereto is fixed to the inner wall of a metal container.

Description of examples Examples of the present invention will be described in detail below.

FIG. 2 shows a half-sectional view of a battery incorporating the safety mechanism of the present invention. In the figure, 11 is a negative electrode case made of nickel-plated iron.
12 is a lithium metal plate, 13 is a separator made of glass non-woven fabric, 14 is a porous carbon electrode made by mixing carbon powder and tetrafluoroethylene powder in a weight ratio of 1d° of 90:10 and press-molding it, and 15 is made of a nickel material. Positive electrode current collector, 1
6 is a welded part where the sealing plate 17 and the battery container 1 are laser welded, 18 is a glass welded part, 19 is a thin part of the sealing plate, 2
o is a shape memory alloy having a composition of 50% Ti and 50% Ni, which is processed into a donut shape, and a cutting edge with a sharp tip is formed at a position corresponding to the thin wall portion 19 of the sealing plate 17.

Reference numeral 22 denotes a peripheral portion formed by bending a shape memory alloy processed into a donut shape into a "pan bottom shape", and this is welded and fixed to the inner wall of the battery container. 23 deforms into a flat plate shape when the battery temperature rises (as shown by the dotted line), and at this time the cutting blade 24 breaks the thin wall part 19 of the sealing plate, discharging the gas and suppressing the increase in internal pressure, causing the battery to burst. 〇Recently used as a memory bank power supply, for example,
+85℃~-55℃ for car electronics related equipment
There is a request to clear the following conditions.

Note that, depending on the temperature resistance conditions, the present invention can also be applied to batteries having a sealed structure using a gasket.

Effects of the Invention The effects of the present invention were confirmed, for example, in a lithium-thionyl chloride battery system having the structure shown in FIG. 2, and were as follows.

While the battery was stored at 80℃, an external short circuit was applied, and the battery temperature decreased to 1.
When the temperature exceeds 00℃, the shape memory alloy returns to a flat plate shape,
The cutting blade pierced through the thin wall of the sealing plate, preventing a rise in internal pressure and preventing the battery from exploding.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a sealed nickel-cadmium battery with a built-in non-recoverable explosion-proof structure, and Fig. 2 is a cross-sectional view of a lithium battery with a built-in fracture structure of the shape memory alloy of the present invention. . 19... Thin wall portion of sealing plate, 2o... Shape memory alloy, 21... Cutting edge, 23... Shape memory alloy returned to flat plate shape. Name of agent: Patent attorney Satoshi Nakao and one other person Figure 1 Figure 2

Claims (1)

[Scope of Claims] 0) A sealed battery characterized by incorporating a shape memory alloy having a sharp cutting edge between a sealing plate and a power generation element. 2. The sealed battery according to claim 1, wherein the shape memory alloy is a Ti-Ni alloy. (3) The sealed battery according to claim 1, wherein the shape memory alloy has a round shape and the peripheral edge thereof is welded to the inner wall of the battery container.