KR20040022003A - Secondary battery - Google Patents

Abstract

PURPOSE: A secondary battery is provided to prevent the counterflow of an electrolyte during the sealing of the electrolyte injection port and the leakage of the electrolyte through the inside of the electrolyte injection port and to improve the battery quality. CONSTITUTION: The secondary battery comprises: an electrode assembly(32) comprising a first electrode plate(32a), a second electrode plate(32b), a separator inserted between both electrode plates, and a first and a second electrode tabs(33a,33b) drawn from the first and the second electrode plates(32a,32b), respectively; a can(31) for enclosing the electrode assembly(32); a cap assembly(40) for sealing the can(31), comprising a cap plate(41) equipped with an electrolyte injection port(42) that is sealed after the injection of the electrolyte into the can; a first and a second terminal parts electrically connected to the first and the second electrode tabs(33a,33b) and insulated each other; and a dam member(48) formed on the bottom of the cap plate(41) and surrounding the electrolyte injection port(42).

Description

Secondary Battery

The present invention relates to a secondary battery, and more particularly, to a secondary battery having an improved structure to prevent electrolyte leakage through an electrolyte injection hole.

Secondary batteries (secondary battery) is a battery that can be charged and discharge, unlike a primary battery that can not be charged, and is widely used in the field of advanced electronic devices such as cellular phones, notebook computers, camcorders. 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 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. In general, a battery is classified into a liquid electrolyte battery and a polymer electrolyte battery according to the type of electrolyte. 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. In addition, lithium secondary batteries are manufactured in various shapes, and typical shapes include cylindrical, rectangular, and pouch types.

1 illustrates a rectangular secondary battery. As shown in FIG. 1, the rectangular secondary battery accommodates an electrode assembly 12 and an electrolyte material in a rectangular can 11 of a rectangular parallelepiped having one surface open. The electrode assembly 12 insulates the positive electrode plate 12a and the negative electrode plate 12b coated with the positive electrode and the negative electrode active material including the positive electrode and the negative electrode active material, respectively, from the separator 12c, and separates the positive electrode plate 12a and the negative electrode from each other. It is formed by winding the electrode plate 12b and the separator 12c in the form of a jelly roll, and a positive electrode tab connected to the positive electrode plate 12a and the negative electrode plate 12b on one side of the electrode assembly 12, respectively. 13a and negative electrode tab 13b are formed. A cap assembly 20 is coupled to an opening of the can 11 to seal the can 11. The cap assembly 20 includes a cap plate 21 for sealing an opening of the can 11, and the cap. An insulating tube 24 inserted into the plate 21, a terminal pin 23 inserted into a hole formed in the insulating tube 24 and electrically connected to the negative electrode tab 13b of the electrode assembly 12; An insulating plate 26 for electrically insulating the negative electrode tab 13b and the cap plate 21, and a terminal plate 25 attached to the lower portion of the insulating plate 26 so as to be insulated from the cap plate 21. It is provided. The positive electrode and the negative electrode tab are bonded to the cap assembly 20, wherein the positive electrode tab 13a is welded to the lower surface of the cap plate 21, and the negative electrode tab 13b is connected to the terminal pin 23 or the terminal plate. Weld on 25. Further, a protective case 14 made of an insulating material is further inserted between the cap assembly 20 and the electrode assembly 12 to prevent a short circuit due to the swing of the electrode assembly 12.

After the cap assembly 20 is bonded to the can 11, the electrolyte is injected through the electrolyte inlet 22, and the plug 27 is pressed onto the electrolyte inlet 22 and then welded to the electrolyte inlet ( 22) Seal.

However, in the related art, when the electrolyte is injected and then the electrolyte injection port 22 is sealed, a phenomenon in which the electrolyte flows back to the electrolyte injection port 22 occurs.

As shown in FIG. 2, after the electrolyte is injected, the electrolyte is buried in the bottom surface of the cap plate 21 to remain as the residual electrolyte R. The residual electrolyte R remains on the smooth surface of the bottom of the cap plate 21 as the electrolyte injected into the can gradually penetrates the electrode assembly. These residual electrolytes R leak through the inner wall of the electrolyte injection hole 22 by pressing the plug 27 against the electrolyte injection hole 22 as shown in FIG. 2 (L). The leakage of the electrolyte is because the surface tension of the bottom surface of the cap plate 21 made of aluminum is weak and the stress of the electrolyte is weak, so that the diffusion of the residual electrolyte R, that is, the bleeding phenomenon occurs. That is, the residual electrolyte R having good diffusion is pushed back to the inner wall of the electrolyte injection hole 22 as the pressure inside the can increases as the plug 27 is pressurized.

The leaked electrolyte L thus flowed back up to the outside of the plug 27 to contaminate the equipment and generate sparks during welding of the plug 27, resulting in a poor sealing, which is caused by a failure of the entire battery.

The present invention is to solve the above problems, an object of the present invention is to provide a secondary battery that can prevent the leakage of electrolyte by blocking the electrolyte flowing back through the electrolyte injection port in advance.

Another object of the present invention is to provide a secondary battery capable of preventing a poor sealing of the electrolyte injection hole.

1 is an exploded perspective view showing a conventional rectangular secondary battery.

FIG. 2 is a partially enlarged cross-sectional view of a portion A of FIG. 1. FIG.

3 is a cross-sectional view of a secondary battery according to an embodiment of the present invention.

4 is a partially enlarged cross-sectional view of a portion B of FIG. 3.

5 is an exploded perspective view showing another preferred embodiment of the dam member shown in FIG.

6 is a cross-sectional view showing the operation of the dam member of the secondary battery according to an embodiment of the present invention according to FIG.

Figure 7 is a partially enlarged cross-sectional view of the cap plate of the secondary battery according to another embodiment of the present invention.

8 is a partially separated perspective view of a cap plate of a secondary battery according to another preferred embodiment of the present invention.

9 is a cross-sectional view showing the operation of the dam member of the secondary battery according to another preferred embodiment of the present invention according to FIG.

<Brief description of the major symbols in the drawings>

31 can 32 electrode assembly

32a: first electrode plate 32b: second electrode plate

33a: first electrode tab 33b: second electrode tab

40: cap assembly 41: cap plate

42: electrolyte inlet 43: terminal pin

44: insulated tube 45: terminal plate

46: insulation plate 47: plug

48,49: dam member

In order to achieve the above object, the present invention is provided with a first electrode plate and a second electrode plate via a separator, and having a first and a second electrode tab drawn out from the first and second electrode plates, respectively. A cap assembly including an electrode assembly, a can including the electrode assembly, a cap plate having an electrolyte injection hole sealed after injecting electrolyte into the can by sealing the can, and the first and second electrodes. It provides a secondary battery comprising a first and second terminal portions electrically connected to each other and insulated from the tab, and a dam member formed on the bottom of the cap plate to surround the electrolyte injection hole.

According to another feature of the invention, the dam member may be provided so that the inner circumferential portion is in contact with the electrolyte injection hole.

According to another feature of the invention, the dam member may be provided so that the inner peripheral portion is spaced apart from the electrolyte inlet by a predetermined distance.

According to another feature of the invention, the dam member may be a hollow disc or hollow polygonal plate.

In the present invention as described above, the dam member may be integrally formed with the cap plate.

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

3 illustrates a secondary battery according to a preferred embodiment of the present invention.

Referring to the drawings, the secondary battery may include a can 31, a jelly-roll electrode assembly 32 accommodated in the can 31, and a cap assembly 40 coupled to an upper portion of the can 31. ).

The can 31 is made of a metal material having a substantially rectangular shape, and according to a preferred embodiment of the present invention, it is possible to perform a terminal role by itself made of aluminum or an aluminum alloy.

The electrode assembly 32 accommodated in the can 31 is provided with a first electrode plate 32a and a second electrode plate 32b via a separator 32c. According to an exemplary embodiment of the present invention, The said 1st electrode plate 32a and the 2nd electrode plate 32b have the shape of the jelly roll wound through the separator 32c. According to a preferred embodiment of the present invention, the first electrode plate may be a positive electrode plate, the second electrode plate may be a negative electrode plate, but the polarity may be reversed.

The positive electrode plate includes a positive electrode current collector made of a strip-shaped metal thin plate, and an aluminum thin plate may be used as the positive electrode current collector.

At least one surface of the positive electrode current collector is coated with a positive electrode mixture including a positive electrode active material, and the positive electrode mixture may include a mixture containing a binder, a plasticizer, a conductive material, and the like in a positive electrode active material of a lithium oxide.

The negative electrode plate may include a negative electrode current collector made of a strip-shaped metal thin plate, and a copper thin plate may be used as the negative electrode current collector.

At least one surface of the negative electrode current collector is coated with a negative electrode mixture, and the negative electrode mixture may be formed of a mixture containing a binder, a plasticizer, a conductive material, and the like in a negative electrode active material of a carbon material.

A separator is provided between one side of the positive electrode plate and one side of the negative electrode plate and the other side of the positive electrode plate, respectively, and the laminate is wound to form an electrode assembly. The separator mutually insulates between the positive electrode plate and the negative electrode plate, and allows active material ions to be exchanged between the electrode plates. The separator is preferably made of sufficient length so as to completely insulate between the electrode plates even if the electrode assembly is contracted and expanded.

The first electrode tab 33a and the second electrode tab 33b are drawn out to an upper portion of the electrode assembly 32 formed as described above. The first electrode tab 33a and the second electrode tab 33b are joined to the first electrode plate 32a and the second electrode plate 32b, respectively. According to an exemplary embodiment of the present invention, the first electrode tab 33a may be a positive electrode tab, and the second electrode tab 33b may be a negative electrode tab. In this case, the first electrode tab 33a may be aluminum or The aluminum alloy and the second electrode tab 33b may be made of nickel or a nickel alloy. As described above, the first electrode tab 33a and the second electrode tab 33b may be configured to have different polarities. Although not shown in the drawings, the insulating tape may be wrapped at portions of the first and second electrode tabs 33a and 33b that protrude to the outside of the electrode assembly 32 to prevent a short circuit between the electrode plates.

The first and second electrode tabs 33a and 33b of the electrode assembly 32 are electrically connected to the first terminal portion and the second terminal portion, respectively, which are exposed to the outside of the secondary battery. In a preferred embodiment of the present invention, the first terminal portion and the second terminal portion may be provided in the can 31 and the cap plate 41 to be described later.

According to a preferred embodiment of the present invention, the cap assembly 40 is to seal the opening of the can 31, the cap plate 41 which may be formed of the same material as the can 31, and the cap It may be provided with a terminal pin 43 formed to be insulated from the plate 41. The terminal pin 43 may be formed through the cap plate 41 through the insulating tube 44, and may be further coupled to the insulating plate 46 and the terminal plate 45 at the bottom of the cap plate 41. have. According to a preferred embodiment of the present invention, the electrode tabs are bonded to the cap assembly 40 as described above, wherein the first electrode tab 33a is bonded to the bottom surface of the cap plate 41 and the second The electrode tab 33b may be bonded to the terminal pin 43. Therefore, according to an exemplary embodiment of the present invention, the cap plate 41 and the can 31 made of the same material may be the first terminal part electrically connected to the first electrode tab 33a, and the terminal pin ( 43 becomes a second terminal portion electrically connected to the second electrode tab 33b. The structure of the cap assembly 40 as described above is not limited to the above-described embodiment, and may be variously modified. That is, as shown in the drawing, rather than having a single terminal pin at the center of the cap plate, two terminal pins are insulated from both sides, and the first and second electrode tabs are joined to each terminal pin. Thus, each terminal pin may be configured to constitute the first and second terminal portions, and any other applicable form may be applied. Reference numeral 34 denotes a protective case and is interposed between the electrode assembly 32 and the cap assembly 40 to prevent rocking of the electrode assembly 32.

The cap assembly 40 as described above is bonded to the opening of the can 31 and sealed, and after the electrolyte is injected into the can 31 through the electrolyte injection hole 42 formed in the cap plate 41, the plug is plugged. The electrolyte injection hole 42 is sealed as a 47. In the present invention, the dam member 48 is disposed on the bottom surface of the cap plate 41 on which the electrolyte injection hole 42 is formed so as to surround the electrolyte injection hole 42. ) May be further provided.

The dam member 48 is to prevent the residual electrolytes buried in the bottom surface of the cap plate 41 from flowing backward to the electrolyte injection port 42 in advance, and as shown in FIG. 4, the cap plate 41 is shown. The bottom surface may be integrally formed with the cap plate 41 around the electrolyte injection hole 42. In this case, as shown in FIG. 4, the inner circumferential portion 48a of the dam member 48 may be in contact with the electrolyte injection hole 42, and inclined outward from the dam member 48 from the inner circumferential portion 48a. This can be formed to extend. This is to allow the electrolyte to flow smoothly from the inner surface of the electrolyte injection port 42.

As shown in FIG. 5, the dam member may be formed as a separate member from the cap plate 41. As shown in FIG. 5, the dam member 48 ′ formed in advance may be formed in a hollow disk shape such that the diameter of the inner peripheral portion 48a ′ is the same as that of the electrolyte injection hole 42. . In this case, the inner circumferential portion 48a ′ may be in contact with the electrolyte injection hole 42. The dam member as described above may be formed in a hollow disc shape as shown in FIG. 5, but is not necessarily limited thereto, and may be applied in any shape as long as it has a structure that can prevent electrolyte from flowing from the other part of the cap plate 41. Can be. That is, although not shown in the drawings, the dam member may be provided in a hollow polygonal plate shape. In addition, when the dam member 48 'is formed as a separate member, the dam member 48' does not need to be formed of aluminum or an aluminum alloy of the same material as the cap plate 41. It can be formed of any material such as metal or insulator.

6 shows the operation of the dam member as described above. 6 illustrates an integrated dam member as shown in FIG. 4, but the same may be applied to a preferred embodiment of the present invention as shown in FIG. 5.

As can be seen in Figure 6, the electrolyte inlet 42 is sealed with a plug 47. At this time, the lower part around the cap plate 41 in FIG. 6 represents the inside of a can which is not shown in figure. When the electrolyte injection hole 42 is sealed in this way, the edge portion of the cap plate 41 is already bonded to the can and the can is sealed, and the electrolyte is injected into the can. In this state, as shown in FIG. 6, residual electrolyte R may remain on the bottom surface of the cap plate 41.

The residual electrolyte R flows in the direction of the electrolyte injection hole 42 when the electrolyte injection hole 42 is pressurized using the plug 47 to be sealed, and at this time, the residual electrolyte R flows. The dam member 48 of the present invention is blocked. Accordingly, the electrolyte solution does not flow to the inner wall of the electrolyte injection hole 42, so that the leakage of the electrolyte through the electrolyte injection hole and the phenomenon that the electrolyte is buried in the welding part may prevent the phenomenon of welding in advance.

Meanwhile, as shown in FIG. 7, the dam member may be formed such that the inner circumferential portion 49a is spaced apart from the electrolyte injection hole 42 by a predetermined distance. The dam member 49 may also be formed integrally with the cap plate 41 as shown in FIG. 7, but may be formed as a separate dam member 49 'as shown in FIG. 8 to be joined to the cap plate 41. . In addition, the dam members 49 and 49 'may be formed in a hollow disk shape, but may be formed in a hollow polygonal plate shape. When the dam members 49 and 49' are formed in a separate dam member 49 ', the material may be a metal material. It may be formed of any material such as an insulator.

9 shows the operation of the dam member 49 according to another embodiment of the present invention. FIG. 9 illustrates an embodiment as shown in FIG. 7, but the same may be applied to the case of the embodiment as shown in FIG. 8.

As shown in FIG. 9, after the electrolyte is injected through the electrolyte inlet 42 of the cap plate 41 that seals the can, residual electrolyte R 1 and R 2 may remain on the bottom surface of the cap plate 41. Can be. At this time, since the inner peripheral portion 49a of the dam member 49 is spaced apart from the electrolyte injection port 42 by a predetermined distance, the electrolyte is inward of the inner peripheral portion 49 of the dam member 49. Even a small amount will remain.

After the electrolyte injection, the electrolyte injection port 42 is pressurized with the plug 47 to seal the residual electrolyte R1 and R2 according to the pressing force of the plug 47. At this time, the residual electrolyte solution R1 remaining outside the dam member 49 is blocked by the flow of the dam member 49, and the remaining electrolyte solution R2 remaining inside the dam member 49 is It is caught by the surface tension between the inner circumferential portion 49a of the dam member 49 and the bottom face of the cap plate 41 so as not to flow toward the electrolyte injection port 42. When the inner circumferential portion 49a of the dam member 49 is too far from the electrolyte injection port 42 so that the amount of the residual electrolyte solution R2 remaining inside of the dam member increases, the residual electrolyte solution R2 is formed in the dam member. Since it is not sufficiently held by the 49 and flows to the electrolyte injection port 42 side, it is preferable that the inner circumferential portion 49a of the dam member 49 is not too far from the electrolyte injection port 42.

As described above, even when the inner circumference of the dam member is formed to be spaced apart from the electrolyte inlet by a predetermined distance, the dam prevents the electrolyte from flowing back to the electrolyte inlet side, thereby preventing welding failure due to the electrolyte leaked in the subsequent plug welding process. It can prevent and solve the electrolyte leakage problem.

According to the present invention as described above, the following effects can be obtained.

First, when the electrolyte injection port is sealed, it is possible to prevent the electrolyte from flowing back to the electrolyte injection port side.

Second, it is possible to prevent the leakage of electrolyte through the inner surface of the electrolyte inlet to prevent welding failure due to the leaked electrolyte when welding the plug sealing the electrolyte inlet.

Third, electrolyte leakage through the electrolyte inlet can be prevented in advance, thereby reducing the battery failure rate.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Could be. Accordingly, the true scope of protection of the invention should be defined only by the appended claims.

Claims (5)

An electrode assembly having a first electrode plate and a second electrode plate provided through a separator, and having first and second electrode tabs respectively drawn out from the first and second electrode plates; A can containing the electrode assembly; A cap assembly including a cap plate having an electrolyte injection hole formed therein to seal the can and inject an electrolyte into the can; First and second terminal portions electrically connected to and insulated from the first and second electrode tabs, respectively; And And a dam member formed on the bottom surface of the cap plate to surround the electrolyte injection hole. The method of claim 1, The dam member is a secondary battery, characterized in that the inner peripheral portion is provided so as to contact the electrolyte inlet. The method of claim 1, The dam member is a secondary battery, characterized in that the inner peripheral portion is provided so that a predetermined distance away from the electrolyte injection port. The method of claim 1, The dam member is a secondary battery, characterized in that the hollow disc or hollow polygonal plate. The method according to any one of claims 1 to 4, The dam member is a secondary battery, characterized in that formed integrally with the cap plate.