KR20040022715A - Lithium secondary battery - Google Patents

Abstract

PURPOSE: A lithium secondary battery is provided, to reduce the number of components by employing a deformation part acting as an electrolyte solution injection hole and to improve the safety by allowing an insulator to be deformed when the internal pressure of a battery exceeds a limit. CONSTITUTION: The lithium secondary battery(20) comprises a battery part(22) comprising a positive electrode plate(23), a separator(24) and a negative electrode plate(25) in turns; a can(21) providing the space where the battery part is received; a cap assembly(200) which is combined to the upper part of the can and has the cap plate(210) formed of an electrolyte solution injection hole, and the electrode terminal(230) penetrating into the inside of the can through the terminal hole formed at the cap plate and inserted with a gasket(220) on the outer surface for the insulation with the cap plate; and an insulator(260) set inside the can, which comprises a plated body part(261) insulating the electrode part and the cap assembly and a deformation part(262) extended from the body part and isolating the electrolyte solution injection hole. Preferably the insulator is made of a highly elastic material.

Description

Lithium secondary battery {Lithium secondary battery}

The present invention relates to a lithium secondary battery, and more particularly, to a lithium secondary battery having an improved structure for isolating a cap assembly and a battery unit by being accommodated inside a can containing 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 advanced electronic devices such as a cellular phone, a notebook computer, and a camcorder. In particular, lithium secondary batteries have a working 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 is 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. Generally, a liquid electrolyte battery and a polymer electrolyte battery are classified 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 lithium secondary batteries are manufactured in various shapes, typical shapes include cylindrical shape, square shape, and pouch type.

1 illustrates a conventional rectangular lithium secondary battery 10.

Referring to the drawings, the lithium secondary battery 10 includes a can 11, a battery unit 12 accommodated in the can 11, and a cap assembly 100 coupled to the can 11. Include.

The can 11 is a rectangular case of a hollow metal material, and the battery part 12 is a jelly-roll type in the order of the positive electrode plate 13, the separator 14, and the negative electrode plate 15. ), And the positive electrode and negative electrode leads 16 and 17 are drawn out from the positive and negative electrode plates 13 and 15, respectively.

The cap assembly 100 includes a cap plate 110 coupled to an upper portion of the can 11, a negative electrode terminal 130 inserted into the cap plate 110 through a gasket 120, and the cap. Insulation plate 140 is provided on the bottom surface of the plate 110, and the terminal plate 150 is installed on the bottom surface of the insulating plate 140 and the cathode terminal 130 is energized.

The positive lead 16 is electrically connected to the cap plate 110, and the negative lead 17 is electrically connected to the negative lead 130 through the terminal plate 150.

The can 11 is disposed under the terminal plate 150, and an insulator 160 is provided to insulate the battery unit 11 from the cap assembly 100. The insulator 260 is seated on an upper surface of the battery unit 22. The insulator 160 is molded of a thermoplastic polymer resin such as polypropylene.

In addition, the cap plate 110 is formed with an electrolyte injection hole 111 that provides a passage through which the electrolyte is injected into the can 11, and the ball 170 is sealable in the electrolyte injection hole 111. Are combined.

On the other hand, the bottom of the can 11 is provided with a safety valve 180 that breaks before other parts when the internal pressure rises due to the abnormality of the battery 10. The safety side 180 is a thin plate-shaped plate thinner than the thickness of the can 11 to cover the through hole formed in the bottom surface of the can 11.

The lithium secondary battery 10 having the above structure has the following problems.

First, in order to insulate the battery assembly 12 of the jelly-roll type from the cap assembly 100, a step of inserting the insulator 160 made of a polymer resin into the can 11 and the cap plate ( Forming an electrolyte injection hole 110 on one side of the 110, and injecting the electrolyte through it, and then sealing using a ball 170, and forming a through hole on the bottom of the can 111, this through hole The process of installing the plate-shaped safety valve 180 to seal the need. As such, the process of assembling the lithium secondary battery 10 becomes complicated, and the number of parts increases. As a result, the manufacturing cost of the lithium secondary battery 10 increases.

Second, the insulator 160 is difficult to maintain a constant tolerance with the can 11, it is difficult to prevent the leakage of the electrolyte.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has an object of providing a lithium secondary battery having an improved structure so as to simultaneously insulate the battery unit and the cap assembly and act as a safety valve and prevent electrolyte leakage. .

1 is an exploded perspective view showing a conventional lithium secondary battery,

Figure 2 is an exploded perspective view showing a lithium secondary battery according to an embodiment of the present invention,

FIG. 3 is a cross-sectional view of a portion of FIG. 2;

<Brief description of symbols for the main parts of the drawings>

20 Lithium rechargeable battery 21 Can

22 Battery ... 23 Anode plate

24 Separator 25 Cathode plate

26 Anode lead 27 Anode lead

200 Cap assembly 210 Cap plate

220 ... gasket 230 ... cathode terminal

240 ... insulated plate 250 ... terminal plate

260 Insulator 261

262 Deformation part 263 Cutoff part

262b ... Deformation space

In order to achieve the above object, a lithium secondary battery according to an aspect of the present invention,

A battery unit arranged in the order of a positive electrode plate, a separator, and a negative electrode plate;

A can providing a space in which the battery unit is accommodated;

An electrode terminal coupled to an upper portion of the can, through which a cap plate having an electrolyte injection hole and a terminal through hole formed in the cap plate penetrate into the can, and having a gasket interposed therebetween for insulating the cap plate. Branched cap assembly; And

And an insulator installed inside the can and having a flat body portion for insulating the battery portion and the cap assembly from each other, and an insulator extending from the body portion and sealing the electrolyte injection hole. .

In addition, the insulator is made of a material of high elasticity to inject a predetermined amount of electrolyte into the interior of the can by penetrating the deformation part through the electrolyte injection hole by an injection means, and then sealing the injection passage by self-restoration. do.

Further, the insulator is in close contact with the bottom surface of the cap plate by an adhesive member to seal the electrolyte injection hole.

In addition, the deformation portion is deformed when the gas generated inside the battery is characterized in that the deformation space is formed to open the passage of the electrolyte injection hole.

In addition, the deformation space is characterized in that the thickness is formed thinner than the deformation so that deformation is preferentially generated by the increased pressure inside the battery.

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

2 illustrates a rectangular lithium secondary battery 20 according to an embodiment of the present invention.

Referring to the drawings, the lithium secondary battery 20 may include a can 21, a battery unit 22 accommodated in the can 21, and a cap assembly 200 coupled to an upper portion of the can 21. ).

The can 21 is a rectangular metal material having a hollow formed therein, and can itself serve as a terminal.

The battery unit 22 accommodated in the can 21 includes a positive electrode plate 23, a negative electrode plate 25, and a separator 24. The positive and negative electrode plates 23 and 25 and the separator 24 each consist of one strip, and are arranged in the order of the positive electrode plate 23, the separator 24, and the negative electrode plate 25 to be wound in a jelly-roll shape. .

In the case of the lithium secondary battery 20, the positive electrode plate 23 is coated with a positive electrode current collector made of thin aluminum, and a positive electrode active material layer containing lithium-based oxide as a main component on both sides thereof, and the negative electrode plate 25 is a thin plate A negative electrode current collector made of copper and a negative electrode active material layer mainly composed of a carbon material are coated on both surfaces thereof.

From the positive electrode plate 23 and the negative electrode plate 25, a positive electrode lead 26 and a negative electrode lead are formed in an electrode uncoated area of the positive electrode collector and the negative electrode collector, that is, an area where the electrode active material layer is not coated. 27) are respectively welded. A part of the positive electrode and negative electrode leads 26 and 27 is drawn out above the battery unit 22 wound in a jelly-roll shape. The anode and cathode leads 26 and 27 may be arranged with different polarities.

Insulating tapes 28 are wrapped in the lead portions of the positive and negative electrode leads 26 and 27 to prevent short circuits between the electrode plates 23 and 25.

A cap plate 210 is provided in the cap assembly 200 coupled to the upper portion of the can 21. The cap plate 210 is a flat metal having a size and shape corresponding to that of the can 21. A terminal hole 212 having a predetermined size is formed in the center of the cap plate 210. An electrolyte injection hole 211 is formed at one side of the cap plate 210.

Through the terminal through hole 212, one electrode terminal, for example, the negative electrode terminal 230 can be installed to be inserted. The outer surface of the negative electrode terminal 230 is provided with a tube-shaped gasket 220 to insulate it from the cap plate 210.

An insulating plate 240 is installed on the bottom surface of the cap plate 210. The terminal plate 250 is installed on the bottom surface of the insulating plate 240. The negative electrode terminal 230 is inserted through the terminal through hole 212 in a state in which the gasket 220 is wrapped, and a bottom surface thereof is exposed downward of the cap plate 210 so that the insulating plate 240 and the terminal plate ( The position is fixed with respect to the cap plate 210 in the state that the 250 is interposed. The bottom portion of the negative electrode terminal 230 is electrically connected to the terminal plate 250.

Here, an insulator 260 is inserted in the upper side of the can 21 in which the battery unit 22 is accommodated to electrically insulate the battery unit 22 from the cap assembly 200. Plays a role of safety valve and electrolyte leakage prevention.

In more detail as follows.

The insulator 260 has a shape that can be inserted into the hollow of the can 21 and has a size that can be fit to the inner wall of the can 21. In addition, the outer surface of the insulator 260 is hermetically contacted with the inner wall of the can 21.

The insulator 260 includes a flat body portion 261 and a deformable portion 262 formed to extend from one edge of the body portion 261.

The main body portion 261 has an insertion hole 261a formed at the center thereof. The insertion hole 261a provides a passage through which the negative electrode lead 27 drawn from the battery unit 22 protrudes upward.

A blocking wall 263 is formed upwardly from one side of the body portion 261 and a short side portion opposite to a portion where the deformation portion 262 is formed. The blocking wall 263 is a portion in which the contact area is expanded to reinforce the sealing property with the inner wall of the can 21 when assembled to the can 21.

The surface where the insertion hole 261a is formed has a height different from that of the deformable portion 262 and the blocking portion 263, when the cap assembly 200 is coupled to the negative lead 27 and the negative electrode terminal 230. In order to provide a space portion that can be connected to, and a space portion on which the insulating plate 240 and the terminal plate 250 can be seated. Alternatively, as long as the outer shape of the main body 261 is a shape corresponding to the hollow of the can 21, it may be formed in other shapes.

The deformable portion 262 is formed integrally with the main body portion 261 and is formed to have a thickness that is substantially thinner than that of other portions of the insulator 260. The deformable portion 262 provides a flat surface 262a so that an upper surface thereof may be in close contact with a lower surface of the cap plate 250. The flat surface 262a may maintain a uniform flatness to completely seal the electrolyte injection hole 211 of the cap plate 250.

A deformation space portion 262b is secured to the lower portion of the flat surface 262a. To this end, the flat surface 262a is formed with a plurality of connecting portions 262c extending downward from both edges, and a groove having a predetermined depth is formed inside the connecting portion 262c to deform the space 262b. To achieve. An end portion of the one side connection portion 262c is integrally connected with the main body portion 261.

The main body 261 and the deformable portion 262 integrally formed therefrom are formed of a high elastic material such as a rubber material or a foamable resin having excellent recoverability. The foamable resin is preferably a rubber foamed resin or a polyethylene foamed resin. The insulator 260 made of a highly compressible material such as a rubber material or a foamable resin can be inserted by being pressed against the inner wall of the can 21 by a predetermined pressure.

3 illustrates a lithium secondary battery 20 in which an insulator 260 is inserted and assembled.

Here, the same reference numerals as in the above-described drawings indicate the same members having the same function.

Referring to the drawings, the battery unit 22 is inserted into the can 21. The cap assembly 200 is welded to the upper portion of the can 21. The negative electrode terminal 230 which can be insulated by the gasket 220 is inserted into the terminal through hole 212 of the cap plate 210, and the lower end of the negative electrode terminal 230 has an insulating plate 240 and a terminal plate. The position is fixed to the lower surface of the cap plate 210 via the medium (250).

In this case, a predetermined space portion 21a is provided on an upper portion of the can 21 on which the battery unit 22 is mounted. The insulator 260 is provided in the space portion 21a. Since the insulator 260 is a rubber material or a foamable resin having excellent compressibility, it is contracted and installed on the inner wall of the can 21, and then restored to be in close contact with the side wall of the can 21.

At this time, the insulator 260 is in close contact with the lower surface of the cap plate 210 with the adhesive member 31 interposed therebetween. Accordingly, the electrolyte injection hole 211 formed in the cap plate 210 is attached to the flat surface 262a, which is the upper surface of the deformable portion 262, to be sealed.

On the other hand, the positive lead 26 drawn from the positive electrode plate 23 of the battery unit 22 is directly welded to the bottom of the cap plate 210. The negative lead 27 drawn from the negative electrode plate 25 protrudes into the insertion hole 261a of the insulator 260, and is welded and electrically connected to the negative electrode terminal 230 through the terminal plate 250. have. Such a connection method may be manufactured with different polarities according to the method of designing the battery 20.

Looking at the operation of the lithium secondary battery 20 having the configuration as described above are as follows.

The battery unit 22 is mounted inside the can 22, and the cap assembly 200 having the insulator 260 attached thereto is inserted into the battery 22 through the adhesive member 31. 20 will be assembled.

Next, the electrolyte is injected into the can 21 through the electrolyte injection hole 211 formed at one side of the cap plate 210. At this time, the insulator 260 is in close contact with the bottom surface of the cap plate 210 on which the electrolyte injection hole 211 is formed. A nozzle, which is an injection means, is inserted through the electrolyte injection hole 221 to penetrate the deformation part 262 and penetrate into the can 22. In this state, a small amount of electrolyte is injected.

After the electrolyte is injected into the can 22, the nozzle is removed. When the nozzle is removed from the deformable portion 262, the electrolyte injection hole 211 can be sealed again by the restoring force of the insulator 260 itself.

On the other hand, when the internal pressure increases due to abnormality of the battery while the lithium secondary battery 20 is operating, gas is generated in the can 21. At this time, the deformable portion 262 is deformed to include a flat surface (262a) when the internal pressure of the threshold value or more is applied. When the flat surface 262a or the plurality of connection portions 262c are deformed toward the deformation space portion 262b, the electrolyte injection hole 211 is opened. It can be said that the gas can be quickly discharged through the electrolyte injection hole 211 opened in this way.

As described above, the lithium secondary battery of the present invention can obtain the following effects.

First, since the deformation part serves as an injection hole of the electrolyte injected through the electrolyte injection hole, a separate means for sealing an electrolyte injection hole is not required, so the number of parts is reduced and the number of manufacturing processes is simplified.

Second, when the internal pressure of the battery exceeds the limit. Since the insulator itself is deformed, the electrolyte injection hole can be opened to thereby quickly prevent gas, thereby improving safety.

Third, since the insulator itself serves as both the electrolyte injection hole and the gas discharge passage, the number of parts is greatly reduced, thereby simplifying the manufacturing process.

Fourth, since the insulator interposed between the battery unit and the cap plate is made of a material that is excellent in resilience, it is easy to maintain the tolerance when the inner wall of the can is combined.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (10)

A battery unit arranged in the order of a positive electrode plate, a separator, and a negative electrode plate; A can providing a space in which the battery unit is accommodated; An electrode terminal coupled to an upper portion of the can, through which a cap plate having an electrolyte injection hole and a terminal through hole formed in the cap plate penetrate into the can, and having a gasket interposed therebetween for insulating the cap plate. Branched cap assembly; And And an insulator installed inside the can and having a flat body portion for insulating the battery portion and the cap assembly from each other, and an insulator extending from the body portion and sealing the electrolyte injection hole. Secondary battery. The method of claim 1, The insulator is made of a material of high elasticity so as to inject a predetermined amount of electrolyte into the can by penetrating a deformation part through the electrolyte injection hole by an injection means, and then close the injection passage by self-restoration. Secondary battery. The method of claim 2, The insulator is a lithium secondary battery, characterized in that the rubber foam resin. The method of claim 2, The insulator is a lithium secondary battery, characterized in that the polyethylene foam resin. The method of claim 2, The insulator is a lithium secondary battery, characterized in that the rubber material. The method of claim 1, The insulator is a lithium secondary battery, characterized in that the close contact with the bottom surface of the cap plate by an adhesive member to seal the electrolyte injection hole. The method of claim 1, The deformation part is a lithium secondary battery, characterized in that the deformation space is formed when the gas generated inside the battery opening the passage of the electrolyte injection hole in the lower portion. The method of claim 7, wherein The deformation space portion is a lithium secondary battery, characterized in that formed by a thickness thinner than the deformation portion so that deformation is preferentially generated by the increased pressure inside the battery. The method of claim 1, The insulator is a lithium secondary battery, characterized in that the outer surface is formed to be in close contact with the predetermined inner wall of the can. The method of claim 1, The main body portion is a lithium secondary battery, characterized in that a space that can be combined with the electrode lead, the electrode lead drawn out from any one of the battery plate of the battery unit.