KR20060086124A - Secondary battery and method for mounting safety valve - Google Patents

Abstract

The present invention provides an electrode group including a separator and a positive electrode plate and a negative electrode plate disposed on both sides of the separator so that the secondary battery can be easily installed by improving the safety valve structure of the secondary battery and obtains uniform operating performance. And a cap assembly coupled to the case to seal it and coupled to a terminal connected to the electrode group, a gas discharge hole formed at one side of the case, and a safety film made of a polymer material installed in the hole and opened under a predetermined pressure condition of the battery. It provides a secondary battery comprising a safety valve comprising.

Safety film, hole, cap plate, step processing part, polymer

Description

SECONDARY BATTERY AND METHOD FOR MOUNTING SAFETY VALVE}

1 is a schematic cross-sectional view showing a secondary battery according to an embodiment of the present invention;

2 is a cross-sectional view showing a portion A in detail in the secondary battery according to an embodiment of the present invention,

Figure 3 is a schematic cross-sectional view showing a safety film installation state of a secondary battery according to another embodiment of the present invention,

4 is a schematic flowchart illustrating a safety film installation process of a rechargeable battery according to an exemplary embodiment of the present invention.

The present invention relates to a secondary battery, and more particularly, to a secondary battery that is easy to install and a safety valve installation method used therefor.

In general, a secondary battery (secondary battery) is a battery that can be charged and discharge, unlike a primary battery that can not be charged, and recently, a high-output secondary battery using a non-aqueous electrolyte of high energy density has been developed, one battery cell pack type In the case of low-capacity batteries that are packaged in small batteries, portable electronic devices such as phones, notebook computers, and camcorders are used. By connecting the two in series or in parallel to form a large capacity secondary battery.

The secondary batteries are manufactured in various shapes, and typical shapes include cylindrical and rectangular shapes. The secondary batteries are wound in a vortex through a separator, which is an insulator, between the two bands and the negative electrode plate. , Jelly roll), or a plurality of positive electrode plates, negative electrode plates, and separators are stacked to form an electrode group, and then built in the case, and a cap assembly having external terminals formed on the case is configured to constitute a battery.

The cap assembly of the secondary battery is installed as a safety device that prevents the explosion of the battery by releasing the gas by breaking under a set pressure condition in addition to the gasket for sealing the external terminal and the case electrically connected to the electrode plate of the electrode group.

By the way, as described above, the secondary battery is provided with a protection circuit such as detecting excessive current during charging and discharging and cutting off the current, but when the protection circuit does not operate normally or an unexpected abnormal reaction of the battery occurs. Gases are generated by chemical reactions inside the battery, which increases the pressure inside the battery, and in severe cases, the battery may explode or burn.

Therefore, conventionally, a pressure release valve that is broken under a certain pressure condition is installed on a cap plate installed in a case, such as Japanese Laid-Open Publication No. 2000-223102, Japanese Laid-Open Patent Publication 1999-219692, or Japanese Laid-Open Patent Publication 1999-25935 to prevent abnormal operation of the battery. There is disclosed a technique that can prevent the explosion.

However, the above-described prior art has a problem in that the pressure release valve is formed during the cap plate manufacturing process, and thus it is not easy to manufacture and it is difficult to expect uniform performance.

The pressure release valve according to the related art is formed of the same material as the cap plate and is formed at the same time as the manufacture of the cap plate, thereby forming an integral structure. For example, the pressure release valve is made of an aluminum material by pressing the pressurized object several times using progressive molds. A pressure release valve integral with the cap plate and the cap plate is made.

However, the above-described conventional structure is difficult to manufacture because the cap plate and the pressure release valve of the thin film must be manufactured at the same time, and the manufactured valve also has a different thickness and the like, and the pressure conditions under which the valve is opened are different. It is difficult to expect uniform performance.

This problem is particularly acute for secondary batteries for HEV (hybrid electric vehicles). For HEV secondary batteries, the size of the battery is larger than that of a small battery for high output capacity, and thus the thickness of the cap plate itself is thicker. You lose. Since the valve must be integrally formed on such a large and thick cap plate, the manufacturing process becomes more difficult, and the required battery characteristics for HEV cannot be obtained.

Therefore, the present invention is to solve the above problems, an object of the present invention is to improve the safety valve structure of the secondary battery can be easily installed and to obtain a uniform operation performance of the secondary battery and the safety valve installation method used therefor In providing.

In order to achieve the above object, the secondary battery of the present invention has a structure in which a safety valve is made of a polymer material and installed in a case.

To this end, the secondary battery of the present invention includes an electrode group including a separator and a positive electrode plate and a negative electrode plate disposed on both sides of the separator, a case in which the electrode group is built, and a terminal connected to the case to seal the separator and connected to the electrode group. A cap assembly to be coupled, a gas discharge hole formed at one side of the case, and a safety film made of a polymer material installed in the hole and opened under a predetermined pressure condition of the battery.

Accordingly, a safety valve is provided separately from the case, and the safety membrane provided in the processed hole on one side of the case is seated and attached to provide a uniform function of the safety membrane as well as easy installation of the safety membrane.

Here, the safety membrane is preferably installed on one side of the cap assembly provided with a terminal electrically connected to the electrode group while sealing the case.

In addition, the safety membrane may be heat-attached to the outer peripheral portion of the hole.

In addition, in the present invention, the hole may be stepped inward, and a safety membrane may be inserted into and fixed to the step processing part of the hole.

In addition, the present invention may include a fastening member fitted to the hole in order to fix the safety film to the step processing portion of the hole.

The fastening member may have a hole communicating with the hole at the center thereof and may be fixed to the step processing part of the hole by interference fit or by welding with the outer peripheral part of the step processing part.

In this case, the hole may have a circular cross section, a quadrangular shape, or a polygonal shape, and preferably has a circular shape.

In addition, the safety valve fitted to the hole and the fastening member also forms the same cross-sectional structure as the hole.

In addition, the step processing portion of the hole may be formed on the inner side or the outer side of the case or cap assembly, and preferably formed on the inner side.

In addition, the present invention is preferably made of a polymer, PP, PE, PFA is excellent in the adhesive strength and heat resistance of the polymer material is difficult to penetrate moisture.

On the other hand, in the secondary battery of the present invention, looking at the method for installing a safety film,

First forming a hole having a step processing part by step machining on one side of the case or cap plate forming the secondary battery;

Positioning a safety film on the step processing part of the hole and attaching the fastening member to the hole to the outside thereof.

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

1 is a schematic cross-sectional view of a rechargeable battery according to an exemplary embodiment of the present invention.

Referring to the secondary battery with reference to the drawings, the secondary battery is the electrode group 10, the positive electrode plate 11 and the negative electrode plate 12 is positioned with the separator 13 between, and the electrode group 10 A case 14 having a built-in space, a cap assembly 30 installed in an opening of the case 14 to seal the case, and electrically connected to each other through the positive and negative electrode plates and the tab 15. (30) includes positive and negative electrode terminals 31 and 32 protruding outward, and a safety valve 20 installed in the cap assembly 30 to discharge gas generated in the battery to the outside.

The case 14 is made of a conductive metal such as aluminum, an aluminum alloy or nickel plated steel, and the shape is made of a cube or other shape having an internal space part in which the electrode group 10 is located.

In the present embodiment, the electrode group 10 is a jelly formed by winding the vortex in the state in which the positive electrode plate 11 and the negative electrode plate 12, each of which is coated on the current collector and laminated with the separator 13 interposed therebetween. It is made of a roll type, and the plain portion 11a of the positive electrode plate and the plain portion 12a of the negative electrode plate are disposed opposite to both ends of the electrode group 10, and the case 14 is vertically raised so that the cap assembly 30 can be turned upside down. It is installed so that the uncoated portions (11a, 12a) of the electrode group 10 is located on both sides of the case 14 relative to when placed in the downward direction, and the uncoated portions of both ends of the electrode group 10 ( The positive and negative terminals 31 and 32 of the cap assembly are electrically connected to each other via tabs 15 (or current collector plates) installed at 11a and 12a, respectively.

And more specifically, the cap assembly 30 is installed on both sides of the cap plate 33 and the cap plate 33 are coupled to each other while maintaining the airtight on the top of the case 14 via a gasket, respectively Positive and negative terminals 31 and 32 electrically connected to the plain portions 11a and 12a of the electrode group via the tab 15, and the safety valve 20 is disposed at the center of the cap plate 33. Has a structure installed.

According to the present embodiment, the safety valve 20 is provided separately from the cap assembly 30 and then assembled to the cap plate 33 of the cap assembly 30.

The safety valve 20 is placed in the hole 22 having the step processing portion 21 which is stepped on the cap plate 33 and faces the inside of the case, and is placed in the step processing portion 21 of the hole 22. The safety film 23 is inserted into the stepped portion 21 of the hole 22 to substantially block / discharge gas, and the safety film 23 is attached to the cap plate while maintaining the airtightness of the safety film 23. It includes a fastening member 24 for fixing.

Accordingly, the safety film 23 provided separately regardless of the structure or size of the cap plate 33 can be easily mounted on the cap plate.

According to this embodiment, the safety layer 23 is made of a polymer material.

Preferably, the safety layer 23 is a thin film and is made of a material having excellent metal adhesion, excellent heat resistance, and difficult to penetrate moisture, for example, made of PP, PE, or PFA.

Here, it is preferable that the step processing portion 21 formed to be stepped with the hole 22 is formed in a circular shape. In response thereto, the safety layer 23 and the fastening member 24 are also formed in a circular cross-sectional structure.

The thickness of the safety film 23 is not particularly limited as long as the safety film 23 is torn and opened within a set pressure range.

In addition, referring to the size of the safety film 23 and the fastening member 24 fitted into the step processing portion 21, the safety film 23 is stepped processing of the hole 22 as shown in FIG. Since it is fitted between the inner circumferential surface of the portion 21 and the outer circumferential surface of the fastening member 24 is preferably formed with a diameter of the size plus the depth of the stepped portion to the inner diameter of the step processing portion 21, Since the fastening member 22 is fitted to the step machining part 21 together with the safety membrane 23, the diameter of the upper fastening member 24 is smaller than the inner diameter of the step machining part 21 formed in the hole 22. It is made small in size so that the safety film 23 can be sandwiched between the inner peripheral surface of the step processing portion 21.

Herein, the structure and thickness of the hole 22, the safety film 23, and the fastening member 24 constituting the safety film 23 are not particularly limited, and according to the characteristics of the battery and the breakdown voltage conditions of the battery. It can be variously modified.

In addition, the safety membrane 23 and the fastening member 24 are made of the same material as the cap plate 33.

In addition, the safety layer 23 is a thin film structure, a groove portion (not shown) may be further formed on one side of the front surface to easily tear the safety layer 23 when the pressure of the battery rises.

In addition, the fastening member 24 has a structure in which a hole 26 corresponding to the hole 22 formed in the cap plate 33 is formed in a ring shape, and the center of the step processing portion 21 is formed. It can be coupled to the inner circumferential surface with the safety film 23 interposed therebetween, and welded to the cap plate 33 in a state of being fitted into the step processing portion 21 of the hole 22 for a more secure fastening. Can be fixed.

Meanwhile, FIG. 3 illustrates a structure in which a safety film provided separately on the cap plate is directly attached to the cap plate as another embodiment of the present secondary battery.

According to the above drawings, the safety valve 20 of the secondary battery has a hole 22 formed on the cap plate 33, and a safety of a polymer material provided separately from the cap plate on the outside of the hole 22. The membrane 23 is positioned, and the safety membrane 23 is heat-attached to the cap plate 33.

Since the safety layer 23 is excellent in adhesive strength with the metal itself, it can be strongly fixed to the cap plate 33 by being directly attached to the cap plate 33 made of a metal material with heat and pressure as described above.

The size of the safety film 23 is formed to a sufficient size to cover the hole 22.

Here, the hole 22 is preferably formed in a circular shape, so that the safety film 23 placed outside the hole 22 is also made in a circular shape.

On the other hand, Figure 4 is a schematic flow chart illustrating a safety valve installation process of a secondary battery according to an embodiment of the present invention, in the following description will be described as an example that the safety film is fixed on the cap assembly by the fastening member. Looking at the process for installing a safety film in the secondary battery with reference to the drawings as follows.

First, the hole 22 is stepped so that the diameter of the front face of the cap plate 33 differs. As a result, a hole 22 having a stepped portion 21 is formed in the cap plate at two steps.

When the hole 22 is formed in the cap plate as described above, a stepped portion of the hole 22 is formed of a polymer safety film 23 which is prepared separately from the cap plate 33 and substantially torn when the internal pressure of the battery rises to release gas. It is located outside the processing part 21.

Therefore, the safety film 23 is in a state of covering the stepped portion 21 of the hole 22.

When the fastening member 24 is inserted into the step processing unit 21 from the outside of the safety film 23, the fastening member 24 is brought into close contact with the safety film 23, and the safety film 23 is fastened to the fastening member ( 24) is coupled between the stepped portion 21 of the cap plate while keeping the airtight.

Through the above process, the safety membrane 23 provided separately from the cap assembly can be easily mounted on the cap plate.

As described above, the secondary battery and the battery module of the present invention can be effectively used when the thickness of the cap plate is thick as an HEV battery requiring high output / large capacity, but the use thereof is not necessarily limited to HEV.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to

As described above, according to the present exemplary embodiment, the safety valve is provided separately from the cap assembly to be coupled later, thereby allowing easy installation of the safety valve regardless of the size of the cap assembly.

In addition, by separately manufacturing a safety film made of a polymer material to be used as a safety valve it is easy to manufacture and the operation of the safety valve is uniform, thereby increasing the reliability of the battery.

Claims (12)

An electrode group including a separator and a positive electrode plate and a negative electrode plate disposed on both sides of the separator, A case in which the electrode group is embedded, a cap assembly coupled to the case to seal the case, and a terminal connected to the electrode group coupled thereto; A safety valve including a gas discharge hole formed at one side of the case and a safety film made of a polymer material installed in the hole and opened under a predetermined pressure condition of the battery; Secondary battery comprising a. The secondary battery of claim 1, wherein the hole is formed at one side of a cap plate having a terminal electrically connected to the electrode group while sealing the case. The rechargeable battery of claim 2, wherein the safety layer is selected from PP, PE, and PFA. The secondary battery of claim 2, wherein the safety layer is attached to an inner surface of the cap plate. The secondary battery of claim 1, wherein the safety layer is fixed to the step processing part via a fastening member fitted to the step processing part formed in the hole. The secondary battery of claim 5, wherein the fastening member has a hole communicating with the hole at a center thereof and is coupled to the step processing portion by a force fitting method. The secondary battery of claim 5 or 6, wherein the fastening member is welded to the step machining part. The secondary battery of claim 1, wherein the safety layer is heated and attached to an outer side of the hole. The secondary battery of claim 1, wherein the secondary battery is for driving a motor. Forming a hole having a stepped portion at one side of a cap plate of a secondary battery; Positioning a safety film outside the step processing portion of the hole; Fixing the safety barrier to the cap plate Safety valve installation method of a secondary battery comprising a. The method of claim 10, wherein the fitting of the safety membrane by close contact includes positioning the fastening member to the outside of the safety membrane and pushing the fastening member into the step processing part of the hole. The method of claim 10, wherein the fixing of the safety film to the cap plate comprises heating and attaching the safety film to the cap plate.

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