KR20040110535A - Secondary battery assembly with gas discharge mechanism by case rupture - Google Patents

Abstract

PURPOSE: Provided is a secondary battery assembly, which has a rupture mechanism to prevent explosion and ignition of a battery when the internal temperature or internal gas pressure of the battery is increased excessively under extreme conditions. CONSTITUTION: The secondary battery assembly(12) comprises: a secondary battery(10) comprising an electrode assembly(24) for generating electricity and a casing(11) for housing the electrode assembly; and a pack(15) for secondary battery, which receives the secondary battery in its inner space and is equipped with a rupture mechanism which can perforate the casing when the secondary battery is expanded. Particularly, the rupture mechanism is at least one protrusion(51) attached on the inner surface of the inner space.

Description

Secondary battery assembly with rupture mechanism {Secondary battery assembly with gas discharge mechanism by case rupture}

The present invention relates to a secondary battery assembly, and more particularly, to a secondary battery assembly having a burst mechanism to prevent explosion and ignition of a battery.

In general, secondary batteries are rechargeable and can be miniaturized and large-capacity. Typically, nickel-hydrogen (Ni-MH) batteries and lithium (Li) secondary batteries are used.

Secondary batteries may be classified into cylindrical batteries using cylindrical aluminum cans, rectangular batteries using rectangular aluminum cans, and pouch-type batteries housed in thin pouch cases, depending on the appearance of the case housing the electrode assembly.

On the other hand, when the internal voltage of the secondary battery increases due to overcharging, gas may be generated, causing the secondary battery case to expand and explode. In particular, lithium ion batteries emit gas such as carbon dioxide or carbon monoxide as the liquid electrolyte decomposes due to overcharging, thereby increasing the internal pressure of the battery. In addition, when an overcurrent flows due to over-discharge or short circuit, the temperature inside the battery rises and the liquid electrolyte turns into a gas. Accordingly, the pressure and temperature inside the battery rise. In particular, there is a risk of ignition. come.

In addition, the secondary battery as described above can be safely used by keeping the temperature conditions at the time of charging and the temperature at the time of use. In the case of severe use environment, that is, the temperature at the time of charging / discharging is excessively high, If the operating temperature is too high, such external temperature conditions may increase the temperature of the battery, causing an explosion or fire.

Therefore, due to the safety issues of such secondary batteries, in addition to safety tests such as overcharge and forced discharge, the high temperature storage test, thermal shock test and thermal exposure ( Various thermal safety tests, including thermal exposure tests, are conducted. This thermal safety test is to leave the battery in different temperature conditions for several tens of minutes to several tens of hours, at which time there should be no explosion or ignition of the battery, and in extreme cases, the battery should be unsealed to prevent explosion and ignition.

Attempts to solve the safety problem of the secondary battery has been progressed so far, in particular, many technologies have been developed to install the safety valve in the secondary battery case to remove the gas inside. Among them, the technique disclosed in US Pat. No. 5,595,835 is to laminate a cover plate and a support plate through a metal thin plate plate, to integrate a laminate by laser welding, and then to form a can containing a power generation element. It seals with a laminated body. Here, the metal thin plate is etched and holes are formed in the cover plate and the support plate. Therefore, when gas is generated such as overcharge and the internal pressure is higher than the designed value, the sealing part is torn off to secure the internal pressure and ensure safety.

However, in such a technique, an additional process is required, resulting in a decrease in productivity, and greatly affected by the conditions of the process, such as an etching process, thereby lowering the burst reliability. In addition, the opposite properties are required in which the laminations must be rupturable with sealability. In addition, rupture of the laminate part due to the breakdown voltage of the battery causes a problem that the entire device is damaged in the case of an electronic device that directly stores the battery in the circuit part. Moreover, in the case of the pouch type secondary battery, since the case is made of a flexible thin plate in which a metal material such as aluminum and a resin material such as a polymer resin are mixed, it is more difficult to provide a safety device according to the prior art.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a simple structure to provide a secondary battery assembly having an improved safety device when the internal pressure of the battery increases due to overcharge, overdischarge, or other overheating conditions. .

1 is a perspective view of a secondary battery assembly according to an embodiment of the present invention;

2 is an exploded perspective view of a secondary battery accommodated in the rechargeable battery pack of FIG. 1;

3, 4 and 5 are cross-sectional views corresponding to the line I-I of FIG. 1, illustrating embodiments of the rupture mechanism;

6 is an operation state diagram of the secondary battery assembly according to FIG.

<Brief description of symbols for the main parts of the drawings>

10 secondary battery 11 case

12 Secondary battery assembly 15 Secondary battery pack

24 ... electrode assembly 31,41,51 ... protrusion

In order to achieve the above object, the secondary battery assembly according to the present invention includes a secondary battery having an electrode assembly for generating electricity, and a case for receiving the electrode assembly;

And a secondary battery pack having a burst mechanism that accommodates the secondary battery in its internal space and opens a hole in the case when the secondary battery is expanded.

The bursting mechanism may be at least one protrusion attached to an inner surface of the inner space. In addition, the rupture mechanism is located on the inner surface of the inner space, may be at least one protrusion formed integrally with the secondary battery pack.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view of a secondary battery assembly according to an embodiment of the present invention, Figure 2 is an exploded perspective view of a secondary battery accommodated in the secondary battery pack of FIG. 3, 4 and 5 are cross-sectional views corresponding to the line I-I of FIG. 1, which illustrate embodiments of the rupture mechanism.

In the drawings, a pouch type secondary battery is illustrated as an example for convenience of description, but the practical features of the present invention described below are not limited to a pouch type battery, but may be equally applied to a rectangular or cylindrical secondary battery. .

As shown in FIG. 1, a secondary battery assembly 12 according to a preferred embodiment of the present invention includes a secondary battery 10 and a secondary battery pack 15 incorporating the secondary battery 10.

Referring to FIG. 2, the secondary battery 10 includes a case 11 and an electrode assembly 24 accommodated in the case 11.

The case 11 forms an inner space to accommodate the electrode assembly 24. Meanwhile, the case of the pouch type secondary battery may be formed of a thin plate in which a metal material such as aluminum and a resin material such as a polymer resin are mixed.

The electrode assembly 24 includes a battery unit 20 for storing a predetermined current, a positive electrode tab 25 and a negative electrode tab 26.

One end of the electrode tabs 25 and 26 is electrically connected to the battery unit 20, and the other end thereof is drawn out to be electrically connected to an external positive electrode terminal and a negative electrode terminal (not shown), respectively. In order to electrically insulate between the case 11 and the electrode tabs 25 and 26, tab tapes 27 are wound around respective portions of the positive electrode tab 25 and the negative electrode tab 26 in contact with the case 11. .

The battery unit 20 includes a positive electrode plate 21, a negative electrode plate 23, and a separator 22 interposed between the electrode plates 21 and 23. Here, the battery unit 20 is formed by winding together the separator 22 between the positive electrode plate 21 and the negative electrode plate 23. The battery unit 20 is not necessarily limited thereto, and the positive electrode plate 21 and the negative electrode plate 23 may be stacked electrode assemblies stacked using the separator 22.

The secondary battery pack 15 is designed with an internal space for accommodating the secondary battery 10. According to one feature of the invention, the inner space portion, when the secondary battery 10 is expanded, is provided with a rupture mechanism that can make a hole in the secondary battery (10). The bursting mechanism may be manufactured by attaching a plate having a plurality of wedge-shaped protrusions 31 to the inner surface of the inner space, as shown in FIG. 3. In addition, as shown in FIG. 4, the rupture mechanism may be manufactured by attaching a plate having a plurality of pins as the protrusion 41 to the inner surface of the space part. In addition, the rupture mechanism may be a protrusion 51 formed integrally with the secondary battery pack and formed on the inner surface of the space, as shown in FIG. 5.

In such embodiments, the protrusions 31, 4, and 51 may be spaced apart from the accommodated secondary battery 10 by a predetermined interval. The predetermined interval is designed as follows. That is, when the internal temperature of the battery 10 rises or the gas pressure inside the battery 10 becomes excessively high due to the overcharging and overdischarging of the secondary battery 10 or the internal short circuit and other overheating conditions, the secondary battery ( 10) will expand. In this case, when the secondary battery 10 expands to reach the protrusions 31, 41, and 51 spaced apart from the predetermined interval, the secondary battery 10 contacts the protrusions 31, 41, and 51, and the case of the secondary battery. 11 is ruptured by the ends of the projections 31, 41 and 51. Thus, the internal pressure is released and the explosion is prevented. Here, the predetermined interval is designed in consideration of the set pressure and the operating environment.

On the other hand, in the above-described embodiments, the protrusions 31, 41, 51 are located on the inner surface facing the widest side of the secondary battery (10).

Next, with reference to FIG. 6, the operation of the secondary battery assembly 12 according to an embodiment of the present invention configured as shown in FIG.

In the secondary battery, when the battery is overcharged or used at a high temperature, the pressure inside the battery increases. Accordingly, the battery is expanded, and this expansion is further increased when swelling occurs. If left unchanged, fire or explosion occurs inside the battery. Therefore, the gas inside the battery must be discharged before such a ignition and explosion occurs.

FIG. 6 illustrates a state in which the secondary battery 10 is expanded due to an increase in the internal pressure of the battery 10. In this case, when the secondary battery 10 is expanded to a predetermined value or more, the secondary battery 10 is formed on the inner surface of the secondary battery pack 15 to the protrusion 51 formed to be spaced apart from one side of the secondary battery 10 by a predetermined interval. Will come. Here, the case 11 of the secondary battery is ruptured by the end of the protrusion 51, the gas inside the battery is discharged through the rupture portion to prevent the battery ignition or explosion.

According to the present invention as described above, the following effects can be obtained.

First, by increasing the thermal safety of the battery, it is possible to prevent the battery from exploding and igniting when the battery is used in a high temperature environment, or the thermal runaway of the battery (thermal runaway).

Second, safety may be ensured even when excessive gas pressure occurs inside the battery due to swelling due to overcharging and other internal short circuits.

Third, it is possible to secure battery safety with a simple structure, without the need to form a separate safety valve, it is possible to lower the production cost and increase the product yield.

Fourth, it is hardly influenced by the production process, and precise process control is unnecessary, so that the reliability of the safety of the secondary battery can be increased when the internal pressure increases.

Fifth, even when the secondary battery case is ruptured due to the increased internal pressure, the secondary battery is embedded in the secondary battery pack, thereby protecting external devices driven by the secondary battery.

Sixth, the present invention is also applicable to a pouch type secondary battery that is difficult to have a separate safety device in the case of the secondary battery.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Could be. Therefore, the true scope of protection of the present invention should be defined by the appended claims.

Claims (5)

A secondary battery having an electrode assembly generating electricity and a case accommodating the electrode assembly; A secondary battery pack having a rupture mechanism, the secondary battery pack having a rupture mechanism capable of accommodating the secondary battery in the inner space and inflating the secondary battery when the secondary battery is expanded; . The method of claim 1, The rupture mechanism is a secondary battery assembly having a rupture mechanism, characterized in that at least one protrusion attached to the inner surface of the inner space. The method of claim 1, The bursting mechanism is located on the inner surface of the inner space, the secondary battery assembly having a burst mechanism, characterized in that at least one protrusion formed integrally with the secondary battery pack. The method according to claim 2 or 3, The protrusion unit is a secondary battery assembly having a rupture mechanism, characterized in that spaced apart from one side of the case by a predetermined interval. The method according to claim 2 or 3, The protrusion is a secondary battery assembly having a rupture mechanism, characterized in that located on the inner surface facing the widest side of the case.