JPH06260161A - Safety valve for non-aqueous electrolyte secondary battery - Google Patents

Abstract

PURPOSE:To provide a non-aqueous electrolyte secondary battery which is free from risk of rupture due to failure such as misuse etc., and excels in the safety and anti-leak performance by furnishing a safety valve exerting good pressure responsiveness. CONSTITUTION:A resilient piece 3 made of fluorine rubber having resistance against organic solvent is provided for blocking an exhaust hole, while a retaining plate 4 of stainless steel having in the center a through hole is furnished to hold the resilient piece 3 by pressure. The upper exhaust hole in a metal sealing lid 2 is held pinchedly by pressure from the outside, while the resilient piece 3 is held pinchedly by pressure in the vertical direction by the retaining plate 4, and the lid 2 and plate 4 are spot welded. The actuation of this safety valve takes place with passing-through of the resilient piece 3 in the center through hole of the retaining plate 4, which is generated when the internal pressure of the battery rises due to gas production etc. As a result, an exhaust port is produced in the battery case, through which the gas is exhausted effectively, so that hazard of battery rupture etc., can be avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety valve used in a non-aqueous electrolyte secondary battery having high energy density and high safety.

[0002]

2. Description of the Related Art With the rapid miniaturization and weight reduction of electronic equipment, the development of a secondary battery that is smaller, lighter in weight and high in energy density, and that can be repeatedly charged and discharged with respect to the power source battery The demand is increasing. Non-aqueous electrolyte secondary batteries are the most promising secondary batteries that meet these requirements.

However, in order for this type of battery to be stably used for a long period of time, a battery caused by a reaction with a battery active material, an electrolyte or the like due to leakage of an electrolytic solution or intrusion of moisture in the air into the battery. Performance degradation must be prevented. Therefore, it is necessary to completely seal the battery, and the sealing is extremely high.

On the other hand, when an external short circuit of this type of battery or a sudden temperature rise due to deterioration of electrodes or separators or overcharging due to excessive voltage, the organic electrolyte is volatilized or decomposed to generate gas. However, this gas may be trapped inside the battery and the internal pressure of the battery may rise significantly. Further, when the battery is exposed to a high temperature such as being dropped into a fire, a runaway reaction between the battery active material such as lithium and the organic electrolyte occurs, and the battery internal pressure rises explosively.
As a result, the battery case may expand and deform, or the battery may burst, which is a serious safety problem.

Conventional reversible safety valves used in lead batteries and Ni-Cd batteries can cope with a gradual increase in internal pressure, but a sudden increase in internal pressure causes an increase in internal pressure due to a low gas discharge capacity. There was a risk that the battery could explode because it could not handle it.

In order to solve such a problem, in the conventional non-aqueous electrolyte battery, a special safety valve device for discharging gas when the internal pressure of the battery rises due to rapid gas generation is provided in the battery case or the sealing body. It was As a typical example, there is one that adopts a hermetic structure using an insulating member (8) such as a glass seal or a ceramic seal as shown in FIG. This is one in which the outer can (6) also serving as one polarity terminal and the metal sealing lid (7) are welded by laser welding or the like, and the other polarity terminal pin (9) is penetrated and fixed in the insulating member (8). is there.

However, in such a battery, due to its high hermeticity, there is a risk of the battery can bursting due to abnormal expansion of the outer can when the battery internal pressure rises under misuse or abnormal environment. In order to prevent the battery from bursting, if the structure is such that the insulating member (8) bursts when the internal pressure of the battery rises, the adhesion with the terminal pin (9) must be weakened, which causes electrolyte leakage. .

In order to prevent the battery from exploding, the outer can (10) is partially thinned at the bottom as shown in FIG. 4, so that the thin groove (11) is broken when the internal pressure of the battery rises. There are things that try to have a structure. However, generally, the outer can is made of iron or stainless steel in order to have mechanical strength, and when forming the thin groove portion (11), the wall thickness is 0.08 to 0.
The reality is that it can only be machined up to about 15 mm. In this case, there is a problem that the explosion-proof function does not operate unless the internal pressure of the battery reaches a high pressure of 40 to 60 kg / cm ² .

[0009]

SUMMARY OF THE INVENTION The present invention is a safety valve comprising an elastic body for closing an exhaust hole, and a holding body for holding the elastic body under pressure and having a through hole in a central portion thereof. When the internal pressure rises abnormally, the elastic body is released from the battery system through the through hole of the holding body to open the battery exhaust hole, thereby solving the above problem. further,
By providing a metal foil on at least a part of the upper part, the lower part or the part between the elastic members, the moisture in the atmosphere is effectively prevented from entering the battery.

[0010]

[Function] Since it is a safety valve with excellent pressure responsiveness and excellent gas discharge efficiency, it does not burst due to abnormal conditions such as throwing into the fire of a battery or misuse, and can improve safety and leak resistance . Further, since this safety valve can be assembled after assembling the battery, it has an excellent effect that it can also serve as a liquid injection port.

[0011]

EXAMPLES The present invention will be described below with reference to preferred examples.

FIG. 1 shows a cross-sectional view of an essential part of an organic electrolyte battery to which an embodiment of the present invention is applied. In the figure, (1) is an outer can, (2) is a stainless steel metal sealing lid having an opening, and the outer can (1) and the metal sealing lid (2) are welded by laser welding or the like, and a power generating element ( (Not shown) is incorporated. (3) is an elastic body made of organic solvent resistant fluororubber, and (4) is a stainless steel holding plate having a through hole in the center. The elastic body (3) is vertically pressed by the holding plate (4) to sandwich the upper exhaust port of the metal sealing cover (2) from the outside, and the metal sealing cover (2) and the holding plate (4) are held together. Spot welded.

The operation of the safety valve is performed by the elastic body (3) passing through the central through hole of the holding plate (4) when the internal pressure of the battery rises due to gas generation or the like. As a result, a discharge port is formed in the battery case, and gas is efficiently discharged from the discharge port, so that a dangerous state such as battery rupture can be avoided. The opening pressure of the safety valve is the opening diameter of the through-hole,
It can be freely set within the range of about 5 kg / cm ² to about 30 kg / cm ² by changing the shape, the elastic modulus of the elastic body, and the shape. Further, since this safety valve can be assembled after injecting the electrolytic solution into the battery, it can also serve as the electrolytic solution injection port.

In addition to the above embodiment, the safety valve can be assembled in the battery by disposing the elastic body (3) and the holding plate (4) inside the opening (2) of the metal sealing lid.
However, in this case, the safety valve cannot also serve as the liquid injection port.

The cross-sectional shape of the outlet of the metal sealing lid (2) of the above embodiment may be bent toward the inside or outside of the case, and the shape of the outlet may be elliptical or rectangular instead of circular.

The sectional shape of the through hole of the holding plate (4) is also
It may be bent inside or outside the case, and the shape of the through hole may be elliptical or rectangular instead of circular.

Further, although the elastic body (3) has a cylindrical shape in the above-mentioned embodiment, the opening pressure of the safety valve can be finely adjusted by forming it into a complicated shape such as a cone or a prism.

Further, as shown in FIG. 2, by providing a metal foil (5) such as aluminum in at least a part of the upper part, the lower part or the intervening part of the elastic body (3), it penetrates into the battery through the elastic body. It is possible to effectively prevent trace moisture in the atmosphere. When aluminum is used, the thickness of the metal foil is preferably 5 to 50 μm.

In the examples, the case where fluororubber is used for the elastic body has been described, but one or more of chloroprene, butyl rubber, silicone rubber, ethylene propylene rubber and the like can be used. Further, the reliability of the battery is further improved by protecting the elastic body from scratches by attaching a protective plate or a protective cap to the elastic body (3) outside the battery.

[0020]

As described above, since the present invention is a safety valve having a good pressure responsiveness, the non-aqueous electrolyte secondary battery does not burst due to abnormal use such as incorrect use of the battery and is excellent in safety and leak resistance. I was able to get

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of a non-aqueous electrolyte battery in an example of the present invention.

FIG. 2 is a cross-sectional view of a main part of a non-aqueous electrolyte battery when an elastic body including a metal foil is used.

FIG. 3 is a cross-sectional view of a main part of a conventional non-aqueous electrolyte battery.

FIG. 4 is a cross-sectional view of a main part of a conventional non-aqueous electrolyte battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 outer can 2 metal sealing lid 3 elastic body made of fluororubber 4 metal holding plate having an opening in the center 5 metal foil 6 outer can 7 metal sealing lid

Claims (2)

[Claims] 1. A safety valve for a non-aqueous electrolyte secondary battery, comprising a sealing lid, an elastic body, and a holding body, wherein the holding plate is fixed to the sealing lid, and the sealing lid has an opening, The holding plate has a through hole in the center, the elastic body is positioned so as to close the opening of the sealing lid, and the periphery is sandwiched between the sealing lid and the holding plate. Safety valve for batteries. 2. The safety valve for a non-aqueous electrolyte secondary battery according to claim 1, wherein a metal foil is provided on at least a part of an upper portion, a lower portion or a portion between the elastic bodies.