KR100591442B1 - Polygonal li secondary battery - Google Patents

Abstract

The present invention relates to a rectangular lithium secondary battery having improved reliability and safety by forming a part of the gasket to cover a portion where the safety vane of the cap plate is formed, thereby preventing the safety vant from being broken by external pressure. The rectangular lithium secondary battery of an electrode assembly having a first electrode plate, a second electrode plate, a separator interposed between the first electrode plate and the second electrode plate; A case having a space for accommodating the electrode assembly; And a cap assembly having a terminal through hole and a safety vent, an electrode terminal inserted into the terminal through hole, and a gasket for insulating the cap plate from the electrode terminal, the cap assembly being coupled to the case to seal the cap assembly. Part of the gasket is characterized in that the outer cover of the safety vent of the cap plate.

Square lithium secondary battery, safety band, gasket

Description

Rectangular Lithium Secondary Battery

1A is an exploded perspective view illustrating a rectangular lithium secondary battery according to an embodiment of the present invention.

Figure 1b is a perspective view after the coupling of the square lithium secondary battery according to an embodiment of the present invention.

Figure 2a is a plan view for explaining the cap assembly of the prismatic lithium secondary battery according to an embodiment of the present invention.

Figure 2b is a cross-sectional view for explaining the cap assembly of the prismatic lithium secondary battery according to an embodiment of the present invention.

(Explanation of symbols for main parts of drawing)

100; Rectangular lithium secondary battery 110; Secondary Battery Case

200; Electrode assembly 210; First electrode plate

215; First electrode tab 220; Second electrode plate

225; Second electrode tab 230; Separator

240; Insulating tape 300; Cap assembly

310; Cap plate 311; Terminal through hole

312; Electrolyte injection hole 313; Bowl

315; Safety van 317; spin

320; Electrode terminal 330; gasket

337; Protrusion coupling portion 340; Insulation Plate

350; Terminal plate 355; Electrode terminal accommodating part

360; Insulated case 400; Protection circuit module

410; Input and output terminals 500; Molding part

The present invention relates to a square lithium secondary battery, and more particularly, a part of the gasket is formed to cover a portion where the safety vane of the cap plate is formed, thereby preventing the safety vane from being broken by external pressure, thereby ensuring reliability and safety. This improved square lithium secondary battery relates.

Recently, compact and lightweight electric / electronic devices such as cellular phones, notebook computers, camcorders, etc. have been actively developed and produced. These portable electric / electronic devices have a battery pack that can be operated in a place where no separate power source is provided. The built-in battery pack includes at least one battery therein for outputting a predetermined level of voltage for driving the portable electric / electronic device for a period of time.

In view of economical aspects, the battery pack employs a secondary battery capable of charging and discharging. Representative secondary batteries include lithium secondary batteries such as nickel-cadmium (Ni-Cd) batteries, nickel-hydrogen (Ni-MH) batteries, lithium (Li) batteries, and lithium ion (Li-ion) batteries.

In particular, the lithium secondary battery has an operating voltage of 3.6 V, which is three times higher than that of a nickel-cadmium battery or a nickel-hydrogen battery, which is widely used as a power source for portable electronic equipment, and is rapidly expanding in terms of high energy density per unit weight. to be.

Such lithium secondary batteries mainly use lithium-based oxides as positive electrode active materials and carbon materials as negative electrode active materials. In general, a battery is classified into a liquid electrolyte battery and a polymer electrolyte battery according to the type of electrolyte, and a battery using a liquid electrolyte is called a lithium ion battery, and a battery using a polymer electrolyte is called a lithium polymer battery. Moreover, although a lithium secondary battery is manufactured in various shapes, typical shapes include cylindrical shape, square shape, and pouch type.

Typically, the lithium ion secondary battery is positioned between the positive electrode plate coated with a positive electrode active material, the negative electrode plate coated with a negative electrode active material, and between the positive electrode plate and the negative electrode plate to prevent a short and to prevent lithium ions (Li-ion). A lithium ion secondary battery case accommodating the electrode assembly, an electrolyte solution injected into the lithium ion secondary battery case to allow lithium ions to move, and the like; .

A rectangular lithium secondary battery of such a lithium secondary battery is formed as follows.

First, the positive electrode active material is coated and the positive electrode tab is connected to the positive electrode tab, the negative electrode active material is coated, the negative electrode plate is connected to the negative electrode tab and the separator is laminated, and then wound to prepare an electrode assembly.

Thereafter, the electrode assembly is accommodated in a case for a lithium secondary battery having a rectangular can shape, and a cap assembly including a cap plate having a safety vane formed on an upper portion of the lithium secondary battery case is assembled to prevent detachment of the electrode assembly. .

After the cap assembly is assembled to the lithium secondary battery case, an electrolyte solution is injected into the lithium ion secondary battery case and sealed.

Then, a protective circuit module is attached to the top of the cap assembly, and the protective circuit module is molded to complete a rectangular lithium secondary battery.

Meanwhile, the process of molding the protective circuit module of the rectangular lithium secondary battery as described above is performed through a hot melting process using hot melt. The hot melting process is generally performed under high pressure conditions of 25 bar to 30 bar.

However, in the process of molding the protective circuit module, an external pressure may act on the safety van by the condition of the high pressure, and thus there is a problem that the safety van of the cap plate is destroyed.

The breakdown of the safety vent causes a problem in that the electrolyte inside the lithium secondary battery leaks. That is, there is a problem that a significant adverse effect on the reliability of the lithium secondary battery.

An object of the present invention is to solve the above-described problems of the prior art, the present invention is formed so that a portion of the gasket can cover the portion where the safety vane of the cap plate is formed to prevent the breakage of the safety van by external pressure It is an object of the present invention to provide a rectangular lithium secondary battery with improved reliability and safety.

The rectangular lithium secondary battery of the present invention for achieving the above object comprises an electrode assembly having a separator interposed between the first electrode plate, the second electrode plate, the first electrode plate and the second electrode plate; A case having a space for accommodating the electrode assembly; And a cap assembly having a terminal through hole and a safety vent, an electrode terminal inserted into the terminal through hole, and a gasket for insulating the cap plate from the electrode terminal, the cap assembly being coupled to the case to seal the cap assembly. Part of the gasket is characterized in that the outer cover of the safety vent of the cap plate.

The cap plate may further include a predetermined protrusion on the opposite side of the terminal through-hole based on the safety vant, and the gasket may further include a protrusion coupling portion coupled to the protrusion.

It is preferable that the softening point of the gasket is 100 ° C. or more, and more preferably, the gasket is made of any one of Teflon and low pressure molded polyethylene.

It is preferable to include a protection circuit module electrically connected to the electrode assembly accommodated in the secondary battery case to control charging, discharging and malfunction of the electrode assembly, and more preferably the protection circuit module It can be provided with input and output terminals.

It is preferable to have a molding part which protects the said protection circuit module and integrates the said cap plate and the said protection circuit module.

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

Like reference numerals in the drawings denote like elements.

1A is an exploded perspective view illustrating a rectangular lithium secondary battery according to an embodiment of the present invention, and FIG. 1B is a perspective view after coupling of a rectangular lithium secondary battery according to an embodiment of the present invention.

1A and 1B, a rectangular lithium secondary battery 100 according to an embodiment of the present invention includes a secondary battery case 110 and a jelly-roll type electrode accommodated inside the secondary battery case 110. An assembly 200, a cap assembly 300 coupled to an upper portion of the secondary battery case 110, a protection circuit module 400, and a molding part 500 protecting the protection circuit module 400 is provided. It is made of a structure.

The lithium secondary battery case 110 is formed of a metal can having a shape of an approximately open box (box) with an upper opening, and may itself serve as a terminal.

The electrode assembly 200 may be attached to any one of the first electrode tab 215 used as the positive electrode tab and the second electrode tab 225 used as the negative electrode tab, for example, the first electrode tab 215. The second electrode plate 220 to which the first electrode plate 210 and the other one of the first electrode tab 215 and the second electrode tab 225, for example, the second electrode tab 225, are attached. And, the separator 230 interposed between the first electrode plate 210 and the second electrode plate 220 is formed in a wound form, it is accommodated in the secondary battery case 110. have. In order to prevent a short circuit between the first electrode plate 210 and the second electrode plate 220 at the boundary portion at which the first electrode tab 215 and the second electrode tab 225 are drawn out from the electrode assembly 200. Each is insulated by an insulating tape 240.

In addition, the first electrode plate 210 and the second electrode plate 220 may be different from each other, and at least one surface of each of the first electrode plate 210 and the second electrode plate 220 may be a positive electrode active material or a negative electrode. The active material is applied. In this case, a chalcogenide compound is used as the cathode active material, and complex metal oxides such as LiCoO 2, LiMn 2 O 4, LiNiO 2, LiNi 1-x Cox O 2 (0 <x <1), and LiMnO 2 are used. As the negative electrode active material, carbon (C) -based materials, Si, Sn, tin oxides, composite tin alloys, transition metal oxides, lithium metal nitrides, or lithium metal oxides are used. In addition, an electrode plate, for example, the first electrode plate 210, which is used as the anode electrode plate among the first electrode plate 210 and the second electrode plate 220, is made of aluminum (Al) and a cathode electrode plate. The electrode plate used as, for example, the second electrode plate 220 is made of a copper (Cu) material, the separator 230 generally uses polyethylene (PE) or polypropylene (PP), but The invention is not limited to the above materials.

The cap assembly 300 is provided with a flat cap plate 310 having a size and shape corresponding to the opening of the secondary battery case 110. A terminal through hole 311 is formed at the center of the cap plate 310, and an electrolyte injection hole 312 for injecting an electrolyte is formed at one side of the cap plate 310, and the electrolyte injection hole 312 is formed. ) Is combined with the bowl 313 to be sealed. In addition, on the other side of the cap plate 310, when the internal pressure of the prismatic lithium secondary battery 100 rises, a safety vent 315 is formed to prevent explosion of the prismatic lithium secondary battery 100. In addition, a predetermined protrusion 317 is formed on a part of the other side of the cap plate 310.

An electrode terminal 320, for example, a negative electrode terminal, may be inserted into the terminal through hole 311. In addition, the outer surface of the electrode terminal 320 is provided with a tube-shaped gasket 330 for electrical insulation with the cap plate 310. In this case, a part of the gasket 330 extends to cover the safety vent 315 of the cap plate 310, and a protrusion coupling part 337 coupled to the protrusion 317 is formed. .

An insulating plate 340 is disposed below the cap plate 310 and attached to a lower surface of the cap plate 310 and includes a through hole 341 corresponding to the terminal through hole 311. The lower surface of the insulating plate 340 is provided with a terminal plate 350 having a through hole 351 corresponding to the terminal through hole 311. In addition, the bottom portion of the electrode terminal 320 is electrically connected to the terminal plate 350 in a state of interposing the insulating plate 340.

The first electrode tab 215 drawn from the first electrode plate 210 is welded to the lower surface of the cap plate 310, and the lower end of the electrode terminal 320 is welded from the second electrode plate 220. The drawn second electrode tab 225 is welded.

On the other hand, the upper surface of the electrode assembly 200 electrically insulates the electrode assembly 200 and the cap assembly 300, and at the same time an insulating case 360 that can cover the upper end of the electrode assembly 200 Is installed. The insulating case 360 is provided with an electrolyte injection hole 362 at a position corresponding to the electrolyte injection hole 312 of the cap plate 310, so that the electrolyte can be injected. The insulating case 360 is an insulating polymer resin, preferably made of polypropylene, but the material is not limited in the embodiment of the present invention.

The protection circuit module 400 may include a first electrode tab 215 and a second electrode tab 225 of the electrode assembly 200 accommodated in the secondary battery case 110 at an upper portion of the cap assembly 300. It is electrically connected to control charging, discharging and malfunction of the electrode assembly 200. For example, when overcurrent flows from the electrode assembly 200, the overcurrent is blocked. In addition, the protection circuit module 400 includes an input / output terminal 410 for charging and discharging the rectangular lithium secondary battery 100 on an upper surface thereof. In addition, the protection circuit module 400 is not shown in the drawings, but generally has a structure having a variety of protection circuits.

The molding part 500 substantially protects the protection circuit module 400, and is a molded part for integrating the cap plate 310 and the protection circuit module 400, and is formed of a foamed resin. In addition, the molding part 500 is formed so that a part of the input / output terminal 410 of the protection circuit module 400 is exposed.

2A is a plan view illustrating a cap assembly of a prismatic lithium secondary battery according to an embodiment of the present invention, and FIG. 2B is a cross-sectional view illustrating a cap assembly of a prismatic lithium secondary battery according to an embodiment of the present invention.

2A and 2B, the cap assembly 300 of the prismatic lithium secondary battery 100 according to an embodiment of the present invention includes a cap plate 310 having a terminal through hole 311 and the terminal through hole 311. ) An electrode terminal 320 inserted into the electrode), a gasket 330 that insulates the electrode terminal 320 and the cap plate 310, an insulating plate 340 attached to a lower surface of the cap plate 310, and the The terminal plate 350 is attached to the lower surface of the insulating plate 340. Here, the configuration of the cap assembly is structurally identical to the cap assembly described in FIGS. 1A and 1B, and thus a detailed description thereof will be omitted.

The cap plate 310 is generally made of a conductive metal, such as aluminum or an aluminum alloy. The cap plate 310 has an electrolyte injection hole 311 formed at a portion of one side of the cap plate 310 based on the terminal through hole 311 and is coupled to the bowl 312 to be sealed. In addition, the cap plate 310 has a safety vent 315 formed to prevent an explosion when the internal pressure of the prismatic lithium secondary battery 100 rises on a portion of the other side of the cap plate 310 based on the terminal through hole 311. have. In addition, a predetermined protrusion 317 is formed at a part of the other side and coupled to the gasket 330. Preferably, the protrusion 317 of the terminal throughhole 311 is based on the safety vent 315. It is located on the opposite side.

The gasket 330 is basically formed in the shape of a tube, and a portion of the gasket 330 is extended to cover the safety vent 315 of the cap plate 310. In addition, a protrusion coupling portion 337 which allows the protrusion 317 and the gasket 330 to be coupled to a portion of the gasket 330, preferably at a position corresponding to the protrusion 317 of the cap plate 310. Is formed. Thus, the gasket 330 is inserted into the terminal through hole 311 of the cap plate 310 together with the electrode terminal 320, a part of which covers the upper portion of the safety vent 315, the protrusion coupling The portion 337 is coupled to the protrusion of the cap plate 310. In this case, the electrode terminal 320 is generally inserted using a spinning method, and the gasket 330 may be prevented from rotating by the protrusion 317 and the protrusion coupling part 337.

In addition, the gasket 330 is preferably made of a material having a softening point of 100 ° C. or more, and more preferably made of any one of the Teflon and low pressure molded polyethylene. The internal temperature of the rectangular lithium secondary battery 100 may rise to about 100 ° C. during the use of the rectangular lithium secondary battery 100, that is, during charging and discharging. In this case, the gasket 330 is softened to This is to prevent the internal sealing of the rectangular lithium secondary battery 100 from being broken.

As described above, in one embodiment of the present invention, the rectangular lithium secondary battery 100 is formed so that the gasket 330 of the cap assembly 300 may cover the safety vent 315 of the cap plate 310. After coupling the cap assembly 300 to the upper portion of the secondary battery case 110 and attaching the protection circuit module 400, the molding part 500 for protecting the protection circuit module 400. It is possible to prevent the destruction of the safety vent 315 that may occur when forming the.

In addition, the gasket 330 is additionally formed to be coupled to the protrusion 317 of the cap plate 310, thereby preventing the gasket 330 from rotating during the insertion process of the electrode terminal 320. can do.

As described above, according to the present invention, the present invention is formed so that a portion of the gasket can cover the portion where the safety van of the cap plate is formed to prevent the breakage of the safety van by external pressure, thereby improving the reliability and safety A lithium secondary battery can be provided.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (7)

An electrode assembly having a first electrode plate, a second electrode plate, a separator interposed between the first electrode plate and the second electrode plate; A case having a space for accommodating the electrode assembly; And a cap assembly having a terminal through hole and a safety vent, an electrode terminal inserted into the terminal through hole, and a gasket for insulating the cap plate from the electrode terminal, the cap assembly being coupled to the case to seal the cap assembly. , Part of the gasket is a rectangular lithium secondary battery, characterized in that for covering the safety band of the cap plate from the outside. The method of claim 1, The cap plate is further provided with a predetermined projection on the opposite side of the terminal hole based on the safety vane, The gasket is a rectangular lithium secondary battery, characterized in that further comprising a projection coupling portion coupled to the projection. The method of claim 1, The softening point of the gasket is a rectangular lithium secondary battery, characterized in that 100 ℃ or more. The method of claim 3, wherein The gasket is a rectangular lithium secondary battery, characterized in that consisting of Teflon or low-pressure molded polyethylene. The method of claim 1, And a protective circuit module electrically connected to the electrode assembly housed in the secondary battery case, the protective circuit module controlling charge, discharge and malfunction of the electrode assembly. The method of claim 5, The protective circuit module includes an input / output terminal for charging and discharging. The method of claim 5, And a molding part which protects the protection circuit module and integrates the cap plate and the protection circuit module.

Images