KR101348218B1 - Secondary Battery Including Heat Shrinking Member - Google Patents

Abstract

The present invention relates to a secondary battery in which an electrode assembly is connected to an electrode terminal of a battery case via an electrode tab, wherein the electrode tab of the electrode assembly is positioned through a central hollow portion and has a cutter mounted at one end thereof; A support member on which the frame member is mounted; And a heat-shrinkable member having one end connected to the frame member at a position opposite to the cutter, the other end opposed to the end being fixed to an inner surface of the support member, and being heat-shrinkable at a predetermined temperature or more. When the temperature rises above, the thermal contraction member is contracted to provide a secondary battery, wherein the electrode tab is cut by a cutter to induce electrical breakdown in the process of pulling the frame member.

Description

Secondary battery including heat shrink member {Secondary Battery Including Heat Shrinking Member}

The present invention relates to a secondary battery in which an electrode assembly is connected to an electrode terminal of a battery case via an electrode tab. More specifically, an electrode tab of an electrode assembly is positioned through a central hollow portion and a cutter is mounted at one end thereof. Frame members; A support member on which the frame member is mounted; And a heat shrink member having one end connected to the frame member at a position opposite to the cutter, and the other end opposite to the end fixed to the inner surface of the support member, the heat shrink member being heat-shrinked at a predetermined temperature or more. When the temperature rises above, the thermal contraction member is contracted to cut an electrode tab by a cutter in the process of pulling the frame member, thereby inducing an electrical short circuit and thus a secondary battery having improved safety.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and accordingly, a lot of researches on batteries that can meet various demands have been conducted.

The lithium secondary battery may be classified into a lithium ion battery, a lithium ion polymer battery, a lithium polymer battery, and the like according to the composition of the electrolyte. A lithium ion battery is a battery having a structure in which a positive electrode / membrane / cathode is impregnated into a lithium electrolyte solution, and a lithium polymer battery is a battery having a structure in which a solid electrolyte is used as an electrolyte in parallel. A lithium ion polymer battery is an intermediate battery of a lithium ion battery and a lithium polymer battery, and is a battery having a structure in which a positive electrode and a negative electrode are bonded to a separator and a lithium electrolyte solution is impregnated at such a part.

The lithium secondary battery may be classified into a cylindrical battery, a square battery, and a pouch battery according to the shape of the battery case. Cylindrical cells and rectangular batteries are batteries having a structure in which an electrode assembly is attached to a metal can, and a pouch type battery is a battery having a structure in which the electrode assembly is attached to a pouch type case of an aluminum laminate sheet, for example.

One of the major research challenges in these cells is to improve safety. For example, a lithium secondary battery may have high temperatures inside the battery, which may be caused by abnormal operating conditions of the battery, such as internal short circuits, overcharge conditions exceeding the allowed currents and voltages, exposure to high temperatures, dropping, or deformation from external shocks. And explosion of the battery by high pressure.

Therefore, essential considerations for the development of a lithium secondary battery are to ensure safety. As an effort to secure such safety, Japanese Patent Application Laid-Open No. 2005-285429, for example, uses a heat shrinkable resin as a means for applying shear stress to a negative electrode current collector having an unformed negative electrode active material region. , The secondary battery having a non-aqueous electrolyte, characterized in that the current is cut off by cutting the portion of the region of the negative active material non-forming region facing the positive electrode active material in the overcharge state, so that when the aluminum-lithium alloy is formed, the current is cut off. Doing.

However, this technique is reliable because the superheated state is maintained until the Al-Li alloy is formed and sufficient alloy forming region is formed to cut off the current flowing from the outside of the battery and the current collector is cut. There is a problem that can not be secured.

Meanwhile, as another prior art, Korean Patent Application Publication No. 2006-0054635 discloses a lithium secondary battery including a cap assembly having a safety vent and a current blocking means, which is formed of a heat shrink film having a predetermined shape and one side of the outer ring and Disclosed is a current blocking means fixed between the insulating rings and having a cutout of a predetermined shape such that the bimetal is in contact with the safety vent, and further comprising a shrink film that insulates the bimetal and the seat belt when the temperature rises.

However, the above technique insulates the bimetal and the safety vent by the heat shrink film, and if any one of them is not functioning, it is not operated, and since the bimetal and the safety vent are included, it is not efficient in terms of manufacturing process and cost. Has its drawbacks.

Therefore, when the battery rises above a predetermined temperature, there is an urgent need for a means for quickly and sensitively operating to cut off the current.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems of the prior art and the technical problems required from the past.

After in-depth research and various experiments, the inventors of the present application have developed a secondary battery including a frame member and a heat shrinkable member on which a cutter is mounted, and such a secondary battery may have a temperature higher than a predetermined temperature. When the heat shrink tube contracts and pulls the frame member, the electrode tab is cut by the cutter to induce electrical short circuit, thereby discovering that the safety of the battery can be greatly improved, and thus the present invention has been completed.

Accordingly, the secondary battery according to the present invention is a secondary battery in which an electrode assembly is connected to an electrode terminal of a battery case via an electrode tab.

A frame member having an electrode tab of the electrode assembly penetrating through the central hollow portion and having a cutter mounted at one end thereof; A support member on which the frame member is mounted; And a heat shrink member having one end connected to the frame member at a position opposite to the cutter, and the other end opposite to the end fixed to the inner surface of the support member and heat-shrinked at a predetermined temperature or more.

Including,

When the temperature rises above the predetermined temperature, the heat shrinkable member is contracted to cut the electrode tab by the cutter in the process of pulling the frame member to induce electrical breakdown.

That is, when the battery or the battery pack is exposed to an abnormal environment and the temperature of the battery rises above a certain temperature due to the external temperature of the battery or the heat generation inside the battery, the cutter is mounted with the shrinkage force generated by the contraction of the heat shrink tube. Since the frame member is moved, the electrode tab is cut by the cutter to ensure the safety of the battery. Therefore, the secondary battery according to the present invention can operate quickly and sensitively with high reliability when an abnormality occurs in the battery.

For example, the frame member may have an outer surface shape corresponding to the inner surface shape of the support member on a horizontal cross section. As one preferred example, the support member may have a rectangular inner surface on a horizontal cross section, and the frame member may have a rectangular outer surface corresponding thereto.

A fastening groove is formed on an inner side of the support member, and a fastening protrusion is formed on a corresponding outer side of the frame member, so that the support member and the frame member can be coupled in an assembly manner by a fastening structure. Therefore, when the heat shrink tube contracts, the fastening protrusion of the frame member moves along the fastening groove inside the support member, thereby effectively cutting the electrode tab.

The heat shrinkable member of the secondary battery according to the present invention may have various structures as long as it has a characteristic of shrinking above a predetermined temperature to operate mechanically according to a change in temperature of the surrounding environment. , Triangles and the like, but are not limited thereto.

In one preferred embodiment, the heat shrinkable member may be a circular or oval hollow structure in a horizontal cross section as a heat shrinkable tube, and a frame member is connected to one end of the heat shrinkable tube, and the other end opposite to the end is supported. It may be a structure fixed to the inner surface.

The material of the heat-shrink tube is not particularly limited as long as it has a property of shrinking above a predetermined temperature. For example, polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, ethylene propylene rubber, isoprene rubber, chloroprene rubber, Styrene butadiene rubber, nitrile butadiene rubber, Teflon and the like can be used in one or two or more combinations. Especially, a polyvinyl chloride material is especially preferable.

The temperature at which heat shrinkage of the heat shrinkable member is started may vary depending on the configuration of the battery, and may be configured to start heat shrinkage at least 70 to 120 ° C. In general, since the lithium secondary battery operates at 70 ° C. or lower in a normal state, the heat shrinkable member is preferably operated at 70 ° C. or higher, which is a temperature at which the lithium secondary battery starts abnormal operation. On the contrary, the internal temperature of the lithium secondary battery is Since the lithium secondary battery may explode when it is 120 ° C. or higher, safety cannot be ensured unless the heat shrinkable member contracts even at 120 ° C.

On the other hand, the heat shrinkable member is not particularly limited as long as it is a shrinkage rate capable of cutting the electrode tab in the above temperature range. For example, the heat shrinkable member may be contracted by 50% or more based on the initial length by heat, preferably 50% to 80%. The electrode tab may be cut by the cutter inside the frame member in the process of pulling the frame member.

In another preferred embodiment, the secondary battery according to the present invention includes two pairs of frame members and a heat shrink member, wherein the first frame member and the first heat shrink member are in a heat shrink direction with respect to the second frame member and the second heat shrink member. It may be a structure that is mounted to form the opposite direction to each other.

Therefore, when the first heat contraction member and the second heat contraction member contract in opposite directions when the battery is overheated, the cutters inside the first frame member and the second frame member are pulled out in the process of pulling the first frame member and the second frame member, respectively. As a result, the electrode tab can be more easily cut and converted into an electrical disconnection state.

The type of secondary battery according to the present invention is not particularly limited, and preferably may be a lithium secondary battery in which safety is a problem.

If the secondary battery has a structure in which the electrode assembly is connected to the electrode terminal of the battery case via the electrode tab, the shape thereof is not particularly limited. For example, the electrode assembly may be a jelly-roll type, a stack type, a stack / The battery may be manufactured in a folding type, or the like, and may be manufactured in a cylindrical can, a square can, or a battery case of a laminate sheet including a metal layer and a resin layer. Since it is well known in the art, detailed description thereof is omitted herein.

The lithium secondary battery according to the present invention may be preferably used as a unit cell for a high output large capacity battery or a battery pack, in which safety problems due to overheating may be particularly serious, and the battery pack is particularly required for an electric vehicle requiring excellent high temperature storage characteristics. It can be preferably used as a power source for a vehicle such as a hybrid electric vehicle.

As described above, in the secondary battery including the frame member and the heat shrinkable member according to the present invention, in the process of pulling the frame member while the heat shrinkable tube contracts when overheating occurs due to an abnormal operation of the battery, the secondary battery includes a cutter mounted on the frame member. By inducing electrical breakdown by cutting the electrode tab, ultimately, the safety of the battery can be ensured.

1 is a schematic diagram showing the mounting process of the frame member and the heat shrink tube is mounted with a cutter according to an embodiment of the present invention;
2A and 2B are some schematic views of a secondary battery including a frame member and a heat shrinkable member on which a cutter is mounted according to one embodiment of the present invention;
3a and 3b are some schematic diagrams showing the cutting process of the electrode tab in the process of pulling the frame member by the contraction of the heat shrinkable member according to an embodiment of the present invention;
4 is a schematic diagram showing a fastening structure of a support member having a fastening groove formed therein and a frame member having a fastening protrusion corresponding thereto according to an embodiment of the present invention.

Hereinafter, the present invention will be described with reference to some drawings, but the scope of the present invention is not limited thereto.

Figure 1 is a schematic diagram showing the mounting process of the support member 500, the frame member (200, 201) and the heat shrink tube (400, 401) is mounted with a cutter according to an embodiment of the present invention.

Referring to FIG. 1, a fastening groove is formed on an inner side surface of the support member 500, and a fastening protrusion is formed on a corresponding outer side surface of the first frame member 200 and the second frame member 201.

In addition, a cutter 300 is mounted at one end of the first frame member 200, a first heat shrinkable member 400 is connected to the other end thereof, and a cutter (20) at one end of the second frame member 201. 301 is mounted, and a second heat shrink member 401 is connected to the other end portion.

The first frame member 200, the second frame member 201 and the support member 500 are coupled in an assembly manner by a fastening structure, and the electrode tab 101 of the electrode assembly 100 is connected to the pair of frame members ( The support member 500 is mounted to the inner surface of the battery case 102.

The first heat contraction member 400 is the second heat shrink member so that the first frame member 200 and the second frame member 201 can cut the electrode tab 101 while moving in opposite directions at a predetermined temperature or more. It is attached to the inner surface of the support member 500 so that the heat contraction direction may form a direction opposite to each other with respect to 401.

2A and 2B illustrate a pair of frame members 200 and 201, a pair of heat shrinking members 400 and 401 connected thereto, and a support member 500 mounted therewith, according to an embodiment of the present invention. It is a schematic diagram of the secondary battery including the support member 500, when the temperature of the battery is a steady state, it shows the form before the heat shrinkable member (400, 401) shrinks.

Referring to these drawings, the electrode tab 101 of the electrode assembly 100 is positioned to penetrate the central hollow portion of the first frame member 200 and the second frame member 201, and The inner surface of the supporting member 500 has a heat shrink direction in which the first heat shrinkable member 400 and the second frame member 201 and the second heat shrinkable member 401 having one end connected to each other form a direction opposite to each other. Composed in an assembly manner by a fastening structure to the opposite positions of the, the support member 500 is located in a predetermined space inside the battery case (102).

3A and 3B illustrate a cutting process of the electrode tab 101 in the process of pulling the frame members 200 and 201 of one phase by contraction of the pair of heat shrinking members 400 and 401 according to one embodiment of the present invention. It is a schematic diagram showing that, after the temperature of the battery rises and the battery is in an abnormal state, a pair of heat shrinkable members (400, 401) shows the form after shrinking.

Referring to these drawings, as the temperature of the battery rises due to the abnormal operation of the battery, the length of the first heat shrinkable member 400 and the second heat shrinkable member 401 shrinks. As described above, one end of the pair of heat-shrinkable members 400 and 401 is connected to the frame member at a position opposite to the cutter, while the other end is fixed at a position opposite to the inner surface of the support member 500. have.

As a result, the first frame member 200 and the second frame member 201 are moved in opposite directions in the contracting process of the first heat shrinkable member 400 and the second heat shrinkable member 401, and thus, in this process, The electrode tab 101 is cut by cutters 301 and 302 moving in opposite directions.

4 is a schematic diagram showing the movement of the frame members 200 and 201 mounted inside the support member 500 when the heat shrinkable members 400 and 401 are contracted.

As described above, a fastening groove is formed on an inner side surface of the support member 500, and a fastening protrusion is formed on a corresponding outer side surface of the first frame member 200 and the second frame member 201, thereby supporting it. The member 500 and the frame members 200 and 201 are coupled in an assembly manner by a fastening structure. Therefore, since the fastening protrusions outside the frame members 200 and 201 move along the fastening grooves inside the frame 500 when the heat shrinkable members 400 and 401 are contracted, the electrode tab 101 may be effectively cut.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (14)

A secondary battery in which an electrode assembly is connected to an electrode terminal of a battery case via an electrode tab,
A frame member in which an electrode tab of the electrode assembly is located through the central hollow portion and a cutter is mounted at one end thereof;
A support member on which the frame member is mounted; And
A heat contraction member having one end connected to the frame member at a position opposite to the cutter, the other end facing the end being fixed to an inner surface of the support member, and heat-shrinked at a predetermined temperature or more;
Including,
When the temperature rises above the predetermined temperature, the secondary battery, characterized in that the heat shrink member is contracted to cut the electrode tab by the cutter in the process of pulling the frame member to induce electrical breakdown. The secondary battery of claim 1, wherein the frame member has an outer surface shape corresponding to an inner surface shape of the support member on a horizontal cross section. The secondary battery of claim 2, wherein the support member has a rectangular inner surface on a horizontal cross section, and the frame member has a rectangular outer surface corresponding thereto. The method of claim 1, wherein the fastening groove is formed on the inner side of the support member, the fastening projection is formed on the corresponding outer side of the frame member, the support member and the frame member is coupled in an assembly manner by the fastening structure Secondary battery characterized in that The secondary battery of claim 1, wherein the heat shrink member is a heat shrink tube. The method of claim 5, wherein the heat shrink tube is one selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, ethylene propylene rubber, isoprene rubber, chloroprene rubber, styrene butadiene rubber, nitrile butadiene rubber, and teflon. Or a secondary battery comprising two or more materials. The secondary battery of claim 6, wherein the heat shrink tube is made of a polyvinyl chloride material. The secondary battery of claim 1, wherein the heat shrinkable member starts heat shrinking at 70 to 120 ° C. 3. The secondary battery of claim 1, wherein the heat shrinkable member contracts by 50% or more based on the initial length by heat. 2. The apparatus of claim 1, comprising two pairs of frame members and a heat shrink member, wherein the first frame member and the first heat shrink member are mounted such that the heat shrink directions are opposite to each other with respect to the second frame member and the second heat shrink member. Secondary battery characterized in that. The secondary battery according to claim 1, wherein the secondary battery is a lithium secondary battery. A battery pack comprising the secondary battery according to claim 1. The battery pack as claimed in claim 12, wherein the battery pack includes two or more pouch-type battery cells as a unit cell. The battery pack according to claim 13, wherein the battery pack is used as a power source for an electric vehicle or a hybrid electric vehicle.

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