KR100788574B1 - Secondary battery - Google Patents

Abstract

-형)로 일정 깊이의 홈이 파이고 상기 열린 부분이 상기 캔의 넓은 측면의 중앙을 향하도록 위치한 벤트를 형성함으로써, 전지 내압에 의한 벤트 파단시 캔의 과도한 파손을 막음과 동시에, 벤트의 파단부 두께를 비교적 두껍게 형성하여 전지의 낙하 같은 외부충격에 의한 벤트의 파손을 방지하고 벤트의 파단부 성형작업을 용이하게 할 수 있다.In the secondary battery according to the present invention, a trapezoid having one side open in the center between two adjacent corner portions of a wide side of the can (

To form a vent positioned so that a certain depth of the groove is formed and the open portion is directed toward the center of the wide side of the can, thereby preventing excessive breakage of the can when the vent breaks due to battery internal pressure, and at the same time, breaking the vent. By forming the thick portion relatively thick, it is possible to prevent the breakage of the vent due to external impact such as the drop of the battery and to facilitate the forming of the break part of the vent.

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 front view of a wide side of the can of the secondary battery shown in FIG. 1;

3 is a perspective view schematically illustrating a process in which the side vent of the secondary battery shown in FIG. 1 is broken;

4 is a tensile stress distribution diagram of a wide side of a can caused by battery internal pressure.

Explanation of symbols on the main parts of the drawings

10: secondary battery 11: can

11a: wide side of the can 12: electrode assembly

100: cap assembly 200: vent

210: upper side 220: left slope

230: right slope

The present invention relates to a secondary battery, and more particularly, in a vent formed at a center between two neighboring corner portions of a wide side of the can, preventing the can from being excessively damaged when the vent breaks due to battery internal pressure, The present invention relates to a secondary battery having a vent shape designed to form a break thickness relatively thick to prevent breakage of the vent due to an external impact such as dropping of the battery, and to facilitate forming of the break portion of the vent.

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. 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 becomes a container of the electrode assembly and the electrolyte solution, and the upper portion opened to insert the electrode assembly is sealed by the cap assembly.

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, and the positive electrode is electrically connected to the cap plate or the can through the positive electrode tab.

Meanwhile, a vent may be formed at one side of the cap plate, or a vent may be formed at one corner of a wide side of the can. Such vents break preferentially than other parts when the internal pressure of the battery increases due to overcharging, etc., thereby releasing internal gas, thereby ensuring safety of the battery. Vents (hereinafter, also referred to as "side vents") formed on the wide side of the can are portions in which breaks having grooves of a predetermined depth are formed.

Conventional side vents are formed at the corners of the can. This is because the greatest tensile stress is applied to the corner when the can is swelled by the pressure of the internal gas. That is, to improve the stability of the battery by placing the side vent in the corner portion, which is the position where the greatest tensile stress is applied to react sensitively to the increase in the internal pressure.

However, when the side vents are located at the corners of the wide side of the can, as described above, the greatest tensile stress is applied to the corners. It spreads to all parts. As a result, the can, which is an outer material protecting the electrode assembly and the electrode tab, may be excessively damaged, resulting in damage to the electrode assembly and / or the electrode tab.

In particular, when the side vent is located at the upper right corner or the upper left corner of the wide side of the can, cracks due to the break of the vent may damage the welding portion of the cap plate coupled to the top of the can, thereby causing an electrode assembly or an electrode tab. You can also get out of the can. Therefore, not only the electrode assembly and / or the electrode tab are damaged, but also there is a problem of lowering the reliability of the battery.

In order to overcome this problem, a secondary battery in which a side vent is formed in the center between two neighboring corner portions of a wide side of the can may be proposed.

However, in the center between the two corner portions, since the tensile stress applied during swelling is smaller than the corner portion, a vent having a thinner fracture portion than the corner portion is required.

Accordingly, when forming the break portion of the vent requires a highly precise molding work, there is a problem that the process cost increases and the working time is delayed.

In addition, there is a risk that the breakage portion of the vent is broken by an external shock such as a drop of the battery.

The present invention is to solve this problem, in the vent formed in the center between the two corners of the wide side of the can, the breakage of the vent and at the same time to prevent excessive breakage of the can during the break The purpose is to design the shape of the vent to form a relatively thick portion to prevent the breakage of the vent due to external impact, such as a battery drop, and to facilitate the forming of the break portion of the vent.

In order to achieve this object, the secondary battery according to the present invention,

-형)로 일정 깊이의 홈이 파이고 상기 열린 부분이 상기 캔의 넓은 측면의 중앙을 향하도록 위치한 벤트가 형성되는 것을 특징으로 한다.Electrode assembly; A can containing the electrode assembly; And a cap assembly coupled to the open top of the can, the trapezoid having one side open at the center between two neighboring corner portions of the wide side of the can (

A groove having a predetermined depth is formed and a vent is formed so that the open portion faces the center of the wide side of the can.

In this case, the vent may be formed at a position corresponding to an upper edge of an approximately quadrangle formed by four corners of the wide side of the can.

Hereinafter, with reference to the accompanying drawings will be described in detail an 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, the secondary battery includes an electrode assembly 12, a can 11 accommodating the electrode assembly 12, and a cap assembly 100 coupled to the can 11.

The electrode assembly 12 typically forms the anode 13 and the cathode 15 in a wide plate shape in order to increase the capacitance, and then separates the separator 14 between the anode 13 and the cathode 15 to insulate them from each other. Laminated and sandwiched and wound into a spiral shape 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. A vent 200 is formed on the wide side of the can, which will be described later.

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 or the can 11. An insulating case 190 may be further installed below the terminal plate 150. On the other hand, the battery may be designed by changing the polarity.

An electrolyte injection hole 112 for injecting an electrolyte into the can 11 is formed at one 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.

Vent 200 formed on the wide side of the can in more detail as follows.

FIG. 2 is a front view of a wide side of the can of the secondary battery illustrated in FIG. 1, and FIG. 3 is a perspective view schematically illustrating a process in which the side vent of the secondary battery illustrated in FIG. 1 is broken.

-형)로 일정 깊이의 홈이 파이고 상기 열린 부분이 캔의 넓은 측면의 중앙을 향하도록 위치한 벤트(200)가 형성되어 있다. Referring to the drawings, the secondary battery according to an embodiment of the present invention, the trapezoid (opening one side in the center between two neighboring corners of the wide side 11a of the can (

Vent-shaped groove is formed, and the vent 200 is formed so that the open portion faces the center of the wide side of the can.

The vent 200 is a portion having a groove having a predetermined depth, and when the pressure caused by the internal gas of the battery increases due to overcharging, etc., the vent 200 breaks preferentially, releasing internal gas, thereby ensuring safety of the battery. Do it.

The tensile stress distribution of the wide side 11a of the can swelled by the internal gas of the battery (where the can has a long side of 48.7 mm and a short side of 33.8 mm), as shown in FIG. It can be seen that the tensile stress increases in the order of the corner portion 21, the planar portion 22, the first corner portion 23, and the second corner portion 24. That is, when the can is swelled by the pressure of the internal gas, the greatest tensile stress occurs at the corner portions 23 and 24.

As shown in Figure 2, according to the present invention by changing the position of the vent formed in the corner portion of the conventional can is formed in the center between two neighboring corner portions, excessive breakage of the can during break of the vent 200 by internal pressure This prevents damage to the electrode assembly and / or the electrode tab.

The vent 200 may be formed at a position corresponding to a long side or a short side of an approximately quadrangle formed by the four corners of the wide side 11a of the can, but corresponds to the short side between the two neighboring corners. It is preferable to be formed in the position to make. In order to have the same breaking pressure, the farther away from the corner where the greatest tensile stress is applied, the thinner the breaking portion of the vent needs to be.

Referring to FIG. 4, it can be seen that a relatively large tensile stress is applied to the upper left and upper right corners of the can, rather than the tensile stress at the lower left and lower right corners of the can. Accordingly, the vent 200 is preferably formed at a position corresponding to an upper side of an approximately quadrangle formed by four corners of the wide side 11a of the can.

Referring to FIG. 2, the upper side 210 of the vent 200 is disposed in parallel with the upper end of the wide side 11a of the can. It is easier to break the break of the vent than the upper side 210 is formed in a straight line is bent. In addition, since the upper edge 210 formed in a straight line at the center of the can is disposed in parallel with the upper end of the can, the tensile stress due to the battery pressure gas acts uniformly on the vent 200, so that the break pressure design of the vent is easy. Become.

Here, the upper side 210 of the vent 200 may be spaced 2.0 to 3.5mm from the upper end of the wide side (11a) of the can. When smaller than 2.0 mm, as shown in FIG. 4, the break of the upper side of the said vent is not easy adjacent to the edge part 21 of the can with the weakest tensile stress. In addition, when larger than 3.5 mm, the area between the second corner portion 24 of the upper left portion and the upper corner portion 24 of the upper right portion where the tensile stress is greatest is out of range, and the break of the upper side of the vent is not easy.

The length of the upper side 210 of the vent 200 is preferably within the range of 0.18 to 0.25 ratio when the length of the horizontal side of the wide side 11a of the can is viewed as a ratio of 1. That is, when the ratio of the length of the upper edge to the length of the horizontal edge is less than 0.18, breakage is not easy, and when larger than 0.25, the reliability of the battery may be lost due to excessive breakage of the can.

-형"의 벤트와 비교해 볼 때, 좌· 우변이 귀퉁이부분에 좀 더 가깝게 위치할 수 있게 되어, 벤트의 파단부의 파단이 용이해진다.2, the left and right inclined sides 220 and 230 of the vent 200 are inclined to form an obtuse angle with the upper side 210, respectively. "

Compared with the "-type" vent, the left and right sides can be located closer to the corner, so that the breakage of the vent is easier to break.

-형"의 벤트와 별 차이가 없어 벤트의 파단부의 파단이 용이하지 않게 되고, 120°보다 크면, 한 변이 열린 사다리꼴에서 상기 열린 부분의 길이가 너무 길게 되어 오히려 벤트의 파단부의 파단이 용이하지 않게 되고, 파단시 내부가스의 방출이 용이하지 않게 된다.In this case, the angle θ formed by the upper side 210 and the left and right inclined sides 220 and 230 may be 100 to 120 °, respectively. If less than 100 °, "

The breakage of the vent is not easy because there is no difference with the "-type" vent, and if it is larger than 120 °, the length of the open portion is too long in the trapezoid of one side, so that the break of the vent is not easy. It is not easy to release the internal gas at the time of breaking.

-형"의 벤트와 별 차이가 없어 벤트의 파단부의 파단이 용이하지 않게 되고, 상변(210)의 길이의 비율이 캔의 넓은 측면(11a)의 가로변의 길이에 ㄷ대하여 0.68 범위보다 작으면, 한 변이 열린 사다리꼴에서 상기 열린 부분의 길이가 너무 길게 되어 오히려 벤트의 파단부의 파단이 용이하지 않게 되고, 파단시 내부가스의 방출이 용이하지 않게 된다.In addition, the positions of the lower end portions (m, n) of the left and right inclined sides (220, 230) are 0.68 to the distance from the left and right ends of the wide side surface 11a of the can to the center of gravity at a ratio of 1. It can be located at the corresponding point within 0.72. As described above, the length of the upper side 210 of the vent 200 is within the range of 0.18 to 0.25 ratio with respect to the length of the horizontal side of the wide side 11a of the can, the inclination of the left and right of the vent 200 Considering that the sides 220 and 230 are inclined to form an obtuse angle with the upper side 210, respectively, if the ratio of the length of the upper side 210 is greater than the range of 0.72 with respect to the length of the horizontal side of the wide side 11a of the can. "

If there is no difference between the vents of the " -type " and the breakage of the vents of the vents is not easy, and the ratio of the length of the upper side 210 is smaller than the 0.68 range for the length of the transverse side of the wide side 11a of the can, In the open trapezoid of one side, the length of the open portion is too long, so that the break of the vent of the vent is not easy, and the release of the internal gas is not easy at the time of breaking.

-형"의 벤트와 "

-형" 벤트의 각 파단부의 두께를 달리하여 파단압 실험 및 낙하 테스트를 실시한 결과이다.next "

"Bent of" type "and"

This is the result of the break pressure test and the drop test by varying the thickness of each break portion of the “-type” vent.

Experimental Example

Two groups of secondary batteries having a rectangular parallelepiped structure having a long side length of 33.8 mm, a long side length of 48.7 mm, and a thickness of 5.0 mm were prepared.

-형)을 띄며 상기 열린 부분이 캔의 넓은 측면의 중앙을 향하도록 위치하는 벤트가 형성되어 있다. One group of secondary batteries (hereinafter referred to as "first sample group") has a square shape with one side open at the center between two neighboring corner portions of the wide side of the can.

Vents are formed so that the open portion faces the center of the wide side of the can.

The upper side of the vent of the first sample group is formed with a length of 7.0 mm parallel to the upper end of the can, 3.0 mm apart from the upper end of the wide side of the can, and the left and right sides each have an angle of 90 ° with the upper side. It is formed in length as much as 5.0mm.

In addition, the fracture | rupture part thickness of the vent of a 1st sample group is 0.04 mm.

-형)을 띄며 상기 열린 부분이 캔의 넓은 측면의 중앙을 향하도록 위치하는 벤트가 형성되어 있다. On the other hand, the other group of secondary batteries (hereinafter referred to as the "second sample group") is a trapezoid (one side open in the center between two adjacent corners of the wide side of the can)

Vents are formed so that the open portion faces the center of the wide side of the can.

The upper side of the vent of the second sample group is formed with a length of 7.0 mm in parallel with the upper end of the can while 3.0 mm away from the upper end of the wide side of the can. The left and right sides of the vent are inclined at an angle of about 106.7 ° with the upper side so that the height of the trapezoid is 5.0 mm and the length of the open portion is 10.0 mm.

In addition, the fracture | rupture part thickness of the vent of a 2nd sample group is 0.06 mm.

First, a break pressure test was performed.

The breaking pressure of the first sample group was 5 to 6 kgf / cm 2 on average, and the breaking pressure of the second sample group was 5 to 7 kgf / cm 2 on average.

From the above experimental results, it can be seen that even though the thickness of the vent break of the second sample group is formed thicker than that of the first sample group, the break pressure has the same break pressure or higher break pressure. This is a phenomenon that occurs when the left and right sides of the vent are formed to be inclined and close to the corners where the tensile stress is large. Therefore, the effort, time, and cost required for forming the break portion of the vent can be saved.

In addition, the second sample group shows a higher breaking pressure than the first sample group, indicating that the internal gas can be discharged at a higher internal pressure. Therefore, the discharge rate and the discharge rate of the internal gas are larger than those of the first sample group.

Then, a free fall experiment of the battery was performed at a height of 1 m.

The breakage portion of the vent was broken at an average of 100 to 150 times in the first sample group, and the breakage portion of the vent was broken at an average of 200 to 300 times in the second sample group.

From the experimental results, it can be seen that the second sample group is more resistant to external shocks such as battery drop than the first sample group. This is because the vent fracture portion of the second sample group is formed thicker than that of the first sample group.

-형"보다 "

-형"인 것이 바람직하다.In the experimental results, the shape of the vent centered between two neighboring corners of the wide side of the can is "

Than "type"

-Type ".

-형)로 일정 깊이의 홈이 파이고 상기 열린 부 분이 상기 캔의 넓은 측면의 중앙을 향하도록 위치한 벤트를 형성함으로써, 전지 내압에 의한 벤트 파단시 캔의 과도한 파손을 막음과 동시에, 벤트의 파단부 두께를 비교적 두껍게 형성하여 전지의 낙하 같은 외부충격에 의한 벤트의 파손을 방지하고 벤트의 파단부 성형작업을 용이하게 할 수 있다.In the secondary battery according to the present invention, a trapezoid having one side open in the center between two adjacent corner portions of a wide side of the can (

To form a vent positioned so that the groove has a certain depth and the open portion faces the center of the wide side of the can, thereby preventing excessive breakage of the can when the vent breaks due to battery internal pressure, and at the same time, breaking the vent. By forming the thick portion relatively thick, it is possible to prevent the breakage of the vent due to external impact such as the drop of the battery and to facilitate the forming of the break part of the vent.

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 (8)

delete delete delete Electrode assembly; A can containing the electrode assembly; In the secondary battery comprising a cap assembly coupled to the open top of the can, A trapezoid with one side open in the center between two adjacent corners of the wide side of the can (

-Shaped), a groove of a certain depth is dug and a vent is formed so that the open portion faces the center of the wide side of the can, and the vent is the upper side of the approximately square center formed by the four corners of the wide side of the can. The upper side of the vent is disposed in parallel with the upper end of the wide side of the can, and the upper side of the vent is spaced 2 to 3.5 mm from the upper end of the wide side of the can. Secondary battery characterized in that the. The method of claim 4, wherein The length of the upper side of the vent is within the range of 0.18 to 0.25 ratio with respect to the length of the horizontal side of the wide side of the can. The method of claim 5, The left and right inclined sides of the vent are inclined to form an obtuse angle with the upper side, respectively. The method of claim 6, Secondary battery, characterized in that the angle formed by the upper side and the left and right inclined sides are 100 to 120 °. The method of claim 6, The lower end portion of the left and right inclined sides of the secondary battery, characterized in that located within a point corresponding to the ratio of 0.68 to 0.72 with respect to the distance from the left and right end of the wide side of the can to the center.

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