KR20080037869A - Secondary battery - Google Patents

Abstract

A secondary battery is provided to prevent a vent from being damaged by external impact such as dropping of a battery, and to improve the time-, labor- and cost-efficiency in forming a vent. A secondary battery(10) comprises an electrode assembly(12), a can(11) for housing the electrode assembly, a cap assembly(100) coupled to the top opening of the can and including a cap plate(110) having a vent(116) with a smaller thickness than other peripheral portions, and an insulated casing(190) disposed between the electrode assembly and the cap assembly. The insulated casing further comprises a protrusion(195) formed upwardly at the portion corresponding to the vent, wherein the protrusion is spaced apart from the vent by a predetermined distance, but is in contact with the vent when the insulated casing is deformed by the internal pressure of the battery or heat exposure conditions.

Description

Secondary Battery {SECONDARY BATTERY}

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

2 is a perspective view of an insulating case used in the secondary battery shown in FIG.

3 is a cross-sectional view of the cap assembly and the insulating case of the secondary battery shown in FIG.

4 is a cross-sectional view of the cap assembly showing a state in which the protrusion of the insulating case deformed by the battery breakdown contact the vent.

Explanation of symbols on the main parts of the drawings

10: secondary battery 11: can

12: electrode assembly 100: cap assembly

110: cap plate 116: vent

190: insulation case 193: plate

194: side wall portion 195: protrusion

The present invention relates to a secondary battery, and more particularly, by forming a protrusion that promotes deformation of a vent in an insulating case, thereby providing a vent having a relatively thick weak part, thereby preventing a breakage of the vent due to an external shock such as a drop of the battery. It relates to a battery.

In general, a secondary battery refers to a battery that can be charged and discharged, unlike a primary battery that cannot be charged, and is widely used in the field of advanced electronic devices such as a cellular phone, a notebook computer, a camcorder, and the like. In particular, lithium secondary batteries have an operating voltage of 3.6V, which is three times higher than nickel-cadmium batteries or nickel-hydrogen batteries, which are widely used as electronic equipment power sources, and are rapidly increasing in terms of high energy density per unit weight.

Such lithium secondary batteries mainly use lithium-based oxides as positive electrode active materials and carbon materials as negative electrode active materials. Moreover, although lithium secondary batteries are manufactured in various shapes, typical shapes include cylindrical shape, square shape, and pouch type.

Among these, the rectangular secondary battery includes an electrode assembly, a can containing the electrode assembly, and a cap assembly coupled to the can.

In the electrode assembly, a positive electrode and a negative electrode and a separator interposed between these two electrodes are wound, and the positive and negative electrode tabs are drawn out from the positive and negative electrodes, respectively.

The can is a metal container having a substantially rectangular parallelepiped shape in a rectangular secondary battery, and is formed by a processing method such as deep drawing.

The cap assembly includes a cap plate coupled to an upper portion of the can, an electrode terminal provided through a terminal hole, and a gasket for insulating the cap plate on an outer surface thereof, an insulating plate installed on a lower surface of the cap plate, and the insulation It is provided on the bottom surface of the plate and comprises a terminal plate that is energized with the electrode terminal.

The negative electrode of the electrode assembly is electrically connected to the electrode terminal through the negative electrode tab and the terminal plate, the positive electrode is electrically connected to the cap plate through the positive electrode tab.

An insulating case may be further installed below the terminal plate, and the insulating case serves to insulate between the electrode assembly and the cap assembly.

Meanwhile, a vent may be formed at one side of the cap plate. Since the vent is thinner than other parts of the surroundings, when the internal pressure of the battery increases due to overcharging or the like, the vent breaks preferentially than other parts, thereby releasing internal gas, thereby ensuring safety of the battery.

However, the conventional vent has the following problems.

Typically, the thickness of the cap plate is 0.8 to 1.0 mm, the thickness of the cap plate of the part where the vent is formed is 70 μm, and the thickness of the fragile part, which is expected to break in the vent when the inside of the battery is abnormal, is 20 to 30 μm. It is only.

As described above, the original vent serves to secure the safety of the battery by being broken by the internal gas pressure of the battery. There is a risk of cracking or breaking of the weak point. In other words, the vent is damaged, thereby reducing the reliability of the battery.

In addition, since the thickness of the weak part in the vent is very thin, there is a limit in designing a secondary battery having a vent operated at a pressure lower than the operating pressure of the existing vent.

In addition, in order to form a vent of such a precise thickness, there is a problem that a highly precise molding operation is required, a manufacturing cost is increased, and a process time is delayed.

The present invention is to solve this problem, by providing a vent having a relatively thick weak part by forming a protrusion to promote the deformation of the vent in the insulating case, to prevent the breakage of the vent due to external impact, such as falling of the battery, The aim is to reduce the effort, cost and time involved in molding the mold.

Secondary battery according to the present invention for achieving this object,

A cap assembly including an electrode assembly, a can housing the electrode assembly, a cap plate coupled to an open upper portion of the can and having a vent thinner than another portion around the can, and between the electrode assembly and the cap assembly. And an insulating case positioned at an upper portion of the insulating case, wherein a protrusion upwardly is formed at a portion of the insulating case corresponding to the vent, and the protrusion is spaced apart from the vent by a predetermined distance, and the battery is exposed to the battery by pressure or heat exposure. Characterized in that the insulating case is made to contact the vent when the deformation.

The insulating case may further include a plate forming a bottom portion, and a sidewall portion extending upward from an edge of the plate, and the protrusion may be formed on the plate.

In this case, the length of the protrusion may be equal to the length of the side wall portion.

In addition, a balance protrusion having the same size and shape as the protrusion may be formed at a position symmetrical with a portion where the protrusion is formed with respect to the center of the plate.

In addition, the shape of the protrusion may be any one selected from hexahedral, cylindrical, conical shape.

Meanwhile, the weakest part having the thinnest thickness is formed in the vent, and the protrusion may be formed at a portion corresponding to the weak part of the insulating case.

In addition, the cap assembly is installed through the cap plate, a terminal through-hole formed in the cap plate and an electrode terminal in which a gasket for insulation with the cap plate is located on the outer surface, the cap plate is installed below the And a terminal plate coupled to the lower end of the electrode terminal, and an insulating plate installed between the cap plate and the terminal plate, wherein the insulating plate and the terminal plate are not located between the vent and the protrusion of the insulating case. It is preferably formed so as not to.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of a secondary battery according to the present invention.

1 is an exploded perspective view illustrating a rechargeable battery according to an exemplary embodiment of the present invention.

Referring to the drawings, a secondary battery 10 according to an embodiment of the present invention is an electrode assembly 12, a can 11 for receiving the electrode assembly 12, and a cap coupled to the can 11 It comprises an assembly 100, and an insulating case 190 for insulating between the cap assembly 100 and the electrode assembly 12.

The electrode assembly 12 typically forms a wide plate shape of the positive electrode 13 and the negative electrode 15 to increase the capacitance, and then interposes a separator 14 between the positive electrode 13 and the negative electrode 15 to insulate them from each other. It is then laminated, rolled up into a vortex to form a so-called 'Jelly Roll'. The negative electrode 15 and the positive electrode 13 may be formed by coating carbon as the negative electrode active material and lithium cobalt as the positive electrode active material, respectively, on a current collector made of copper and aluminum foil. The separator 14 is made of polyethylene, polypropylene, or a copolymer of polyethylene and polypropylene. Separator 14 is formed to be wider than the positive electrode 13 and the negative electrode 15 is advantageous to prevent short circuit between the electrode plates. In the electrode assembly 12, positive and negative electrode tabs 16 and 17 connected to each electrode are drawn out. An insulating tape 18 is wound around the positive and negative electrode tabs 16 and 17 to prevent a short circuit between the electrode plates 13 and 15 at the boundary portion drawn out of the electrode assembly 12.

The can 11 is a metal container having a substantially rectangular parallelepiped shape in a rectangular secondary battery as shown, and formed by a processing method such as deep drawing. It is therefore possible for the can itself to act as a terminal. As the material for forming the can, aluminum or aluminum alloy, which is a lightweight conductive metal, is preferable. The can 11 becomes a container of the electrode assembly 12 and the electrolyte solution, and the upper part opened to the electrode assembly 12 is sealed by the cap assembly 100.

The cap assembly 100 includes a cap plate 110, an electrode terminal 130, an insulating plate 140, and a terminal plate 150. The cap plate 110 has a terminal through hole 111 formed therein, and the electrode terminal 130 penetrates through the terminal through hole 111 with the gasket 120 positioned on the outer surface thereof to insulate the cap plate 110. Is installed. An insulating plate 140 is provided on the lower surface of the cap plate 110, and a terminal plate 150 is provided on the lower surface of the insulating plate 140. The lower end of the electrode terminal 130 is coupled to the terminal plate 150.

The negative electrode 15 of the electrode assembly 12 is electrically connected to the electrode terminal 130 through the negative electrode tab 17 and the terminal plate 150. In the case of the positive electrode 13 of the electrode assembly 12, the positive electrode tab 16 is welded to the cap plate 110. On the other hand, the battery may be designed by changing the polarity.

An insulating case 190 is installed below the terminal plate 150 to insulate between the cap assembly 100 and the electrode assembly 12. The insulating case may be made of PP (polypropylene) and may be injection molded. It can manufacture by such a method. This insulating case 190 will be described later.

A vent 116 is formed at one side of the cap plate 110. The vent 116 serves to ensure safety of the battery by releasing internal gas when the internal pressure of the battery increases due to overcharging. The vent 116 is formed to be thinner than other portions of the cap plate 110, and when the internal pressure increases, the vent 116 is first broken to release the internal gas.

An electrolyte injection hole 112 for injecting an electrolyte into the can 11 is formed at the other side of the cap plate 110, and a sealing unit 160 for sealing the electrolyte injection hole 112 after electrolyte injection is provided. Is formed.

The shape of the insulating case 190 is as follows.

Referring to FIG. 1, an upward protrusion 195 is formed at a portion of the insulating case 190 corresponding to the vent 116 formed on the cap plate 110, and the protrusion 195 is usually a vent 116. ) Is spaced apart from the predetermined distance and is in contact with the vent 116 when the insulating case 190 is deformed by the battery breakdown voltage or heat exposure. To this end, the insulating plate 194 and the terminal plate 150 need not be located between the vent 116 and the protrusion 195 of the insulating case 190.

Referring to FIG. 2, the shape of the insulating case is described in more detail. The insulating case 190 includes a plate 193 forming a bottom portion and a sidewall portion 194 extending upward from an edge of the plate 193. The protrusion 195 is formed on the plate 193. In addition, the plate 193 includes a hole 191 through which the negative electrode tab passes, a side groove 191 formed in the side of the plate 193 so that the positive electrode tab passes, and a hole 192 through which the electrolyte passes. Formed.

Although not shown, a balance protrusion having the same size and shape as the protrusion 195 may be formed at a position symmetrical with a portion where the protrusion 195 is formed based on the center of the plate 193. If the thickness of the plate is thick, the capacity of the battery is reduced, so it is necessary to form a thin plate.On the other hand, if only the protrusion is formed and the center of gravity of the insulation case is pulled to one side, the insulation case may be damaged by external force such as torsion of the battery or internal pressure of the battery. Since the problem can easily be reversed, it is to maintain the center of gravity of the insulated case by forming a balanced protrusion in a position symmetrical with the protrusion to prevent this.

The shape of the protrusion may be any one selected from hexahedron, cylinder, and cone. However, the content of the present invention is not limited thereto.

Figure 3 shows the shape of the cap assembly and the insulating case of the above-described shape. When an external shock such as a drop of the battery is applied, the sidewall portion 194 contacts the edge of the lower surface of the cap plate 110 while the plate 193 of the insulating case 190 maintains a flat shape, and the protrusion 195 is vented. 116). In this case, the length of the protrusion 195 may be formed to be the same as the length of the side wall portion 194.

However, as shown in FIG. 4, when the plate 193 of the insulating case 190 is bowed upward by the internal gas pressure of the battery, the protrusion 195 is configured to contact the vent 116. That is, the protrusion 195 may facilitate deformation of the vent 116. This phenomenon may occur even when the shape of the insulating case 190 is deformed by heat exposure.

Therefore, it is possible to have a vent having a relatively thick weak portion than the existing vent, it is possible to prevent the breakage of the vent due to external impact such as falling of the battery, and to reduce the effort, cost and time required to mold the vent do.

Furthermore, the weakest part having the thinnest thickness is formed in the vent 116, and the protrusion 195 may be formed at a portion of the insulating case 190 corresponding to the weakest part. In this case, since the magnetic pole is directly applied to the weak part in the vent by the protrusion of the insulating case, the thickness of the weak part of the vent to be designed to be broken by the same internal pressure as before can be increased.

According to the secondary battery according to the present invention, by providing a vent having a relatively thick weak portion by forming a protrusion for promoting the deformation of the vent in the insulating case, to prevent the breakage of the vent due to external impact, such as falling of the battery, forming the vent This will save you a lot of effort, money and time.

Although the present invention has been described with reference to the illustrated embodiments, it is merely exemplary, and the present invention may encompass various modifications and equivalent other embodiments that can be made by those skilled in the art. Will understand.

Claims (7)

A cap assembly including an electrode assembly, a can housing the electrode assembly, a cap plate coupled to an open upper portion of the can and having a vent thinner than another portion around the can, and between the electrode assembly and the cap assembly. In the secondary battery comprising an insulating case located in, A protrusion upwardly is formed on a portion of the insulating case corresponding to the vent, and the protrusion is spaced apart from the vent by a predetermined distance so that the protrusion comes into contact with the vent when the insulation case is deformed by battery pressure or heat exposure. Secondary battery, characterized in that made. The method of claim 1, The insulating case further includes a plate forming a bottom portion, and a sidewall portion extending upward from an edge of the plate, wherein the protrusion is formed on the plate. The method of claim 2, The length of the protrusion is a secondary battery, characterized in that the same as the length of the side wall. The method of claim 2, The secondary battery, characterized in that the balance protrusion having the same size and shape as the protrusion is formed in a position symmetrical with the portion formed with the protrusion relative to the center of the plate. The method of claim 1, The shape of the protrusion is a secondary battery, characterized in that any one selected from hexahedron, cylinder, cone. The method of claim 1, The secondary battery, characterized in that the weak portion having the thinnest thickness is formed in the vent, the protrusion is formed in a portion corresponding to the weak portion of the insulating case. The method of claim 1, The cap assembly may be installed through the cap plate, a terminal through hole formed in the cap plate, and an electrode terminal having a gasket for insulation from the cap plate on an outer surface thereof, and installed below the cap plate. It comprises a terminal plate coupled to the lower end of the, and the insulating plate is installed between the cap plate and the terminal plate, The secondary battery, characterized in that the insulating plate and the terminal plate is not located between the vent and the protrusion of the insulating case.

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