KR20050121903A - Secondary battery and cap assembly and safety valve using the same and method for mounting safety valve - Google Patents

Abstract

The present invention provides a secondary battery in which an electrode group in which a positive electrode plate and a negative electrode plate are positioned with a separator interposed therebetween is installed inside the case so that the safety valve structure of the secondary battery can be easily installed and uniform operation performance can be obtained. Provided is a secondary battery including a stepped hole on one side of the case, and a safety valve which is placed and attached to the stepped surface of the hole and is opened under a set pressure condition of the battery.

Description

SECONDARY BATTERY AND CAP ASSEMBLY AND SAFETY VALVE USING THE SAME AND METHOD FOR MOUNTING SAFETY VALVE}

The present invention relates to a secondary battery, and more particularly, to a cap assembly of a secondary battery and a secondary battery that is easy to install, and a method of installing a safety valve used therein.

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 packaged with a battery, a small electronic device such as a phone, a notebook computer, a camcorder, and the like are used for portable electronic devices. Connected 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 further includes a safety device that prevents the battery from being exploded by releasing gas by breaking under a set pressure condition in addition to a gasket for sealing an external terminal and a 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, in the prior art, a pressure release valve that is damaged 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 a 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.

That is, the pressure release valve according to the prior art is made of the same material as the cap plate and is formed at the same time as the manufacture of the cap plate to form an integral structure, for example, 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 secondary battery cap assembly and the To provide a safety valve installation method used.

In order to achieve the above object, the secondary battery of the present invention has a main point that a safety valve is manufactured and installed separately from a case.

To this end, the present invention

In a secondary battery in which an electrode group in which a positive electrode plate and a negative electrode plate are positioned with a separator interposed therebetween is provided in a case,

And a stepped hole at one side of the case, and a safety valve disposed on and attached to the stepped surface of the hole and opened under a predetermined pressure condition of the battery.

As a result, a safety valve is provided separately from the case, and the safety valve provided in the stepped hole is separately seated and installed on one side of the case, so that the safety valve can be easily installed and the safety valve can be uniformly operated. .

In addition, the present invention may further include a fastening member fitted to the step surface of the hole to fix the safety valve.

Here, the secondary battery is preferably installed in a rectangular case of the electrode group is wound in the shape of a jelly roll.

In addition, the secondary battery may be a secondary battery for HEV.

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

Here, the safety valve is preferably made of the same material as the case or cap plate formed with a hole.

In addition, the safety valve may be formed in the groove portion formed in the thickness of the flesh to be opened in a predetermined pressure condition on the front surface.

In addition, the safety valve may be attached to the fastening member on one surface to form a clad (clad) form.

Preferably, the safety valve and the fastening member is made of the same material.

In addition, the fastening member is preferably formed with a hole in the center communicating with the hole and fixed to the case or cap plate by welding.

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 stepped surface of the hole may be formed on the inner surface or the outer surface of the case or cap plate, preferably formed on the inner surface.

On the other hand, the cap assembly of the secondary battery according to the present invention,

And a cap plate having a stepped mounting hole, a positive and negative electrode terminal electrically connected to the electrode group installed on the cap plate, and installed in the case, and a safety valve placed on the step surface of the hole.

In addition, the cap assembly of the present invention may further include a fastening member which is fitted to the step surface to fix the safety valve in the airtight state.

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

First forming a hole having a stepped surface by being stepped on one side of the case or cap plate forming the secondary battery;

Fitting a fastening member having a safety valve attached to the stepped surface of the hole;

And welding the fastening member to the case or the cap plate.

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, and FIG. 2 is a cross-sectional view illustrating a portion A of FIG. 1 in detail as 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 and the electrode group 10 in which the positive electrode plate 11 and the negative electrode plate 12 are located between the separator 13, and the electrode group 10 is 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 outwardly, and a safety device 20 installed in the cap assembly 30 to discharge gas generated inside 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 a cap plate 33 which is coupled to the airtight state on the top of the case 14 via a gasket, and installed on both sides of the cap plate 33 and each tab Positive and negative terminals 31 and 32 electrically connected to the non-coated portions 11a and 12a of the electrode group via the medium 15, and the safety device 20 is provided at the center of the cap plate 33. It is installed structure.

According to this embodiment, the safety device 20 is provided separately from the cap assembly 30 and then assembled to the cap assembly 30.

The safety device 20 is placed in the step 22 of the cap plate 33 and has a step surface 21 facing the inside of the case, and is placed in the step surface 21 of the hole 22 and substantially. The safety valve 23 for blocking / discharging gas and the stepped surface 21 of the hole 22 are fastened to fix the safety valve 23 to the cap plate while maintaining the airtightness of the safety valve 23. And a member 24.

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

Here, it is preferable that the stepped surface 21 formed to be stepped with the hole 22 is formed in a circular shape, and the safety valve 23 and the fastening member 24 placed on the stepped surface 21 also have a stepped surface 21. To have a circular shape having a size corresponding to the size of.

The size and the like of the structure and thickness of the hole 22, the safety valve 23 and the fastening member 24 constituting the safety device is not particularly limited, and various modifications are made depending on the characteristics of the battery and the withstand voltage condition of the battery. Can be.

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

In addition, the safety valve 23 is a plate structure, the groove portion 25 is formed on the front so that the safety valve 23 can be easily torn when the pressure of the battery rises to form a thin thickness of the safety valve 23 It is a structure made.

In addition, the fastening member 24 is formed in a ring shape with a hole 26 corresponding to the hole 22 formed in the cap plate 33 at the center thereof, and is placed on the step surface 21 to be provided with the cap plate 33. It is fixed by welding.

As described above, the fastening member 24 is provided separately from the safety valve 23 to be mounted on the step surface 21, or attached to one side of the safety valve 23 to form a clad (clad). It is prepared in a state that can be mounted on the step surface 21 of the hole 22, such as a safety valve (23).

Meanwhile, FIG. 3 illustrates a structure in which a safety valve 23 separately provided in the cap plate 33 is directly attached to another embodiment of the secondary battery.

According to the above-described drawings, the safety device 20 of the secondary battery forms a stepped hole 22 on the cap plate 33, and the cap plate is formed on the step surface 21 of the hole 22. The safety valve 23 provided separately is brought into close contact with each other, and is welded and fixed by laser welding along a contact surface between the cap plate 33 and the safety valve 23.

At this time, the stepped surface 21 of the hole formed in the cap plate 33 so that the height thereof corresponds to the thickness of the safety valve 23 when the safety valve 23 is fitted into the hole safety valve ( 23) and the side of the cap plate is preferably made the same height.

In addition, Figure 4 is a cross-sectional view showing another embodiment of the present secondary battery, according to the above-described drawings, the safety device 20 of the secondary battery is on one surface of the safety valve 23 installed in the hole 22 The fastening member 24 is attached, and the safety valve 23 is fitted such that the fastening member 24 is placed on the step surface 21 of the hole 22, and the cap plate 33 and the safety valve 23 are attached. The contact surface of) is welded and fixed by laser welding.

Here, it is preferable that the stepped surface 21 formed to be stepped with the hole 22 is formed in a circular shape, and the safety valve 23 and the fastening member 24 placed on the stepped surface 21 also have a stepped surface 21. To have a circular shape having a size corresponding to the size of.

3 and 4, the reference numeral 25, which is not described, is a groove formed to easily tear the safety valve 23 when the pressure of the battery rises.

On the other hand, Figure 5 is a schematic flow chart illustrating a safety device installation process of the secondary battery according to an embodiment of the present invention, in the following description will be described as an example that the safety valve is fixed on the cap assembly by the fastening member. Looking at the process for installing the safety device 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 surface 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 surface 21 of the hole 22 is provided with a safety valve 23 which is prepared separately from the cap plate 33 and substantially torn when the internal pressure of the battery rises to release gas. )).

Here, the safety valve 23 may be provided in various diameters and thicknesses according to the size of the cap plate or the characteristics of the battery separately from the cap plate 33 of the battery, and may be used for the battery.

Therefore, the safety valve 23 has a size corresponding to the stepped surface 21 of the hole 22 and is placed on the stepped surface 21 as described above, thereby blocking the hole 22.

When the fastening member 24 is inserted into the stepped surface 21, the fastening member 24 is brought into close contact with the safety valve 23 placed on the stepped surface 21. It is coupled between the stepped surface 21 of the cap plate while keeping the airtight.

In this state, when finally welded (W) by ultrasonic welding along the contact surface of the fastening member 24 and the cap plate, the fastening member 24 is fixed to the cap plate and the installation of the safety device is completed.

Accordingly, the safety valve 23 provided separately from the cap assembly can be easily mounted to the cap plate through the above process.

Meanwhile, when the fastening member 24 is attached to one surface of the safety valve 23 to form a body in a clad form, the fastening member 24 to which the safety valve 23 is attached is directly opened to the hole ( 22, the safety device can be installed more simply by welding with laser welding or the like along the contact surface of the fastening member 24 and the cap platen.

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 enabling easy installation of the safety valve regardless of the size of the cap assembly.

In addition, since the safety valve is manufactured separately, the operation of the safety valve is uniform, thereby increasing the reliability of the battery.

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,

3 and 4 is a schematic cross-sectional view showing a safety valve installation state of a secondary battery according to another embodiment of the present invention,

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

Claims (21)

In a secondary battery in which an electrode group in which a positive electrode plate and a negative electrode plate are positioned with a separator interposed therebetween is provided in a case, And a stepped hole at one side of the case, and a safety valve placed and attached to the stepped surface of the hole and opened under a set pressure condition of the battery. 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 secondary battery of claim 2, wherein the safety valve is made of the same material as the cap plate. The secondary battery of claim 3, wherein the safety valve has a groove portion formed on the front surface thereof so as to have a thin thickness to be opened at a predetermined pressure condition. The secondary battery of claim 2, wherein the stepped surface of the hole is formed on an inner surface of the cap plate. The secondary battery of claim 1, further comprising a fastening member fitted to a stepped surface of the hole outside the safety valve seated in the hole to fix the safety valve. The secondary battery of claim 1, further comprising a fastening member disposed between the stepped surface of the hole and the safety valve. The rechargeable battery of claim 6, wherein the fastening member is attached to one surface of the safety valve. The secondary battery of claim 8, wherein the fastening member has a hole communicating with the hole at a center thereof and fixed to the cap plate by welding. The rechargeable battery of claim 9, wherein the fastening member is made of the same material as the cap plate. The secondary battery of claim 1, wherein the electrode group is wound in a jellyroll form, and the case is rectangular. The secondary battery of claim 1, wherein the secondary battery is for HEV. A cap plate having a stepped mounting hole, Positive and negative terminals, which is installed on the cap plate and electrically connected to the electrode group installed in the case, Safety valve is placed on the stepped surface of the hole and attached, Cap assembly of a secondary battery comprising a. The cap assembly of claim 13, wherein the safety valve has a groove formed on the front surface thereof so as to have a thin thickness to be opened at a predetermined pressure condition. The cap assembly of claim 13, further comprising a fastening member fitted to a stepped surface of the hole outside the safety valve seated in the hole to fix the safety valve. The cap assembly of claim 13, further comprising a fastening member disposed between the stepped surface of the hole and the safety valve. The cap assembly of claim 15 or 16, wherein the fastening member is attached to the safety valve. 18. The cap assembly of claim 17, wherein the fastening member has a hole communicating with the hole at the center thereof and fixed to the cap plate by welding. Forming a hole having a stepped surface on one side of a cap plate of the secondary battery; Attaching a safety valve to a step surface of the hole to closely contact the safety valve; Fixing the safety valve to the cap plate Safety valve installation method of a secondary battery comprising a. 20. The rechargeable battery of claim 19, wherein the fitting of the safety valve comprises attaching a fastening member to one surface of the safety valve and inserting the safety valve into the hole so that the fastening member contacts the step surface of the hole. How to install the safety valve. 20. The method of claim 19, further comprising fitting the fastening member to the outside of the safety valve fitted to the step surface of the hole, and welding and fixing the cap plate and the safety valve to each other.