阅读说明：本技术 包括其中形成有槽部的衬垫的圆柱形二次电池 (Cylindrical secondary battery including gasket having groove portion formed therein ) 是由 朴旻熙 金世元 车焄 罗鍾胜 金相佑 朴相俊 于 2020-05-18 设计创作，主要内容包括：公开了一种圆柱形二次电池,配置为使得在第一衬垫和第二衬垫的每一个的形状被修改的状态下应用第一衬垫和第二衬垫,以便确保气密密封性和绝缘性。圆柱形二次电池包括：圆柱形罐,配置为容纳包括正极、负极和隔膜的电极组件；位于圆柱形罐的上部的盖组件；第一衬垫,配置为在被添加以覆盖盖组件的顶盖的外周边缘和通气构件的外周边缘的状态下气密地密封圆柱形罐；位于盖组件的下部的电流中断装置(CID)；和位于电流中断装置的外周边缘的第二衬垫,其中第一衬垫的上端部具有配置为覆盖顶盖的外周边缘的上表面的结构,并且在第一衬垫的上端部的内表面的至少一部分中形成有槽部,槽部配置为防止第一衬垫与顶盖的外周边缘的上表面紧密接触。(Disclosed is a cylindrical secondary battery configured such that a first gasket and a second gasket are applied in a state in which the shape of each of the first gasket and the second gasket is modified, in order to ensure airtight sealability and insulation. The cylindrical secondary battery includes: a cylindrical can configured to receive an electrode assembly including a positive electrode, a negative electrode, and a separator; a cap assembly located at an upper portion of the cylindrical can; a first gasket configured to hermetically seal the cylindrical can in a state of being added to cover a peripheral edge of the top cap of the cap assembly and a peripheral edge of the vent member; a Current Interrupt Device (CID) located at a lower portion of the cap assembly; and a second gasket located at a peripheral edge of the current interruptive device, wherein an upper end portion of the first gasket has a structure configured to cover an upper surface of the peripheral edge of the top cap, and a groove portion configured to prevent the first gasket from coming into close contact with the upper surface of the peripheral edge of the top cap is formed in at least a part of an inner surface of the upper end portion of the first gasket.)

1. A cylindrical secondary battery comprising:

a cylindrical can configured to receive an electrode assembly including a positive electrode, a negative electrode, and a separator;

a cap assembly located at an upper portion of the cylindrical can;

a first gasket configured to hermetically seal the cylindrical can in a state of being added to cover a peripheral edge of a top cap of the cap assembly and a peripheral edge of a vent member;

a Current Interrupt Device (CID) located at a lower portion of the cap assembly; and

a second gasket located at a peripheral edge of the current interrupt device, wherein,

the upper end portion of the first gasket has a structure configured to cover an upper surface of a peripheral edge of the top cover, and

a groove portion is formed in at least a portion of an inner surface of the upper end portion of the first gasket, the groove portion being configured to prevent the first gasket from coming into close contact with an upper surface of a peripheral edge of the top cover.

2. The cylindrical secondary battery according to claim 1,

the top cap includes a bridge portion configured to connect a protruded central portion of the top cap and an outer peripheral edge of the top cap to each other, and

the groove portion is formed in the upper end portion of the first gasket facing an outer peripheral edge of the top cap connected to the bridge portion.

3. The cylindrical secondary battery according to claim 2, wherein a length connecting opposite ends of the groove part is greater than a width of the bridge part.

4. The cylindrical secondary battery according to claim 1, wherein the groove portion is integrally provided with a groove having a uniform depth.

5. The cylindrical secondary battery according to claim 1, wherein the groove part has a structure in which concave parts and convex parts are alternately formed.

6. The cylindrical secondary battery according to claim 5, wherein each of the protruding portions has a thickness equal to that of the upper end portion of the first gasket, at which the groove portion is not formed.

7. The cylindrical secondary battery according to claim 5, wherein each of the protruding portions has a thickness smaller than that of the upper end portion of the first gasket, at which the groove portion is not formed.

8. The cylindrical secondary battery according to claim 1, wherein the upper end portion of the first gasket has a porous structure.

9. The cylindrical secondary battery according to claim 1,

the second gasket includes: an upper portion located at an upper surface of an outer peripheral portion of the current interrupt device, the upper portion configured to prevent contact between the vent member and the current interrupt device; and a side portion located outside an outer peripheral portion of the current interrupt device, and

a stamped portion is formed in at least a portion of the upper portion.

10. The cylindrical secondary battery according to claim 9, wherein the punched portion is formed at a position adjacent to a positive electrode tab coupled to the current interruptive device.

11. The cylindrical secondary battery according to claim 9, wherein the punched portion is formed in a shape in which a portion of the inner side of the upper portion of the second gasket is removed.

12. The cylindrical secondary battery according to claim 9, wherein the punched part has a structure in which a groove is formed in a lower surface of an upper portion of the second gasket.

13. The cylindrical secondary battery according to claim 12, wherein the groove is formed in a slit shape.

Technical Field

The present application claims priority from korean patent application No. 2019-0072473, filed on 18.6.2019, the disclosure of which is incorporated herein by reference in its entirety.

The present invention relates to a cylindrical secondary battery including a gasket in which a groove part is formed, and more particularly, to a cylindrical secondary battery including a gasket in which a groove part is formed, in which the shape of the gasket adjacent to a high-temperature portion of a cap assembly is modified, thereby improving the resistance of the cylindrical secondary battery to high temperatures.

Background

The lithium secondary battery is classified into: a cylindrical secondary battery having an electrode assembly mounted in a cylindrical metal can, a prismatic secondary battery having an electrode assembly mounted in a prismatic metal can, and a pouch-shaped secondary battery having an electrode assembly mounted in a pouch-shaped case made of an aluminum laminate sheet. Among these batteries, the cylindrical secondary battery has advantages in that the capacity of the cylindrical secondary battery is relatively large and the cylindrical secondary battery is structurally stable.

The cylindrical secondary battery is configured such that the cap assembly is located at the open upper end of the cylindrical case, and the cylindrical secondary battery is hermetically sealed in a state in which a gasket is interposed between the cylindrical case and the cap assembly.

Fig. 1 is a vertical sectional view of a conventional cylindrical secondary battery. Referring to fig. 1, the cylindrical secondary battery 100 is configured such that a jelly-roll type electrode assembly 110 is received in a cylindrical battery case 120, a cap assembly 130 is located at an upper portion of the cylindrical battery case 120, and the cylindrical secondary battery 100 is hermetically sealed by a first gasket 133 of the cap assembly 130.

The cap assembly 130 includes: a safety vent 132 positioned at a lower portion of the top cap in a state of covering an outer circumference of the top cap 131, and a current interruptive device 134 positioned below the safety vent 132 in a state of contacting a central portion of the safety vent 132. The second gasket 135 is located at the outer circumferential edge of the current interrupt device 134, and the second gasket 135 is configured to prevent the safety vent 132 and the current interrupt device 134 from contacting each other at portions other than the central portion of the safety vent 132.

The positive electrode tab 111 of the jelly-roll type electrode assembly 110 is attached to the lower surface of the current interrupt device 134 such that the cap assembly 130 serves as a positive electrode terminal.

In connection with this, a portion of the top cover 131 where the gas discharge port is not formed is overheated due to heat generation of the positive electrode tab, and a portion of the first gasket in close contact with the heat generation portion of the top cover is highly likely to be melted. In the case where the first gasket is melted, there may occur a problem in that the hermetic seal of the secondary battery is deteriorated or a problem in that electrical conduction is caused due to contact between the battery case and the cap assembly.

Fig. 2 is a lower perspective view illustrating a positional relationship between the second gasket and the positive electrode tab of fig. 1.

Referring to fig. 2, a positive electrode tab 111 attached to and extending from the jelly-roll type electrode assembly is bonded to a current interrupt device (not shown). In the case where the end portion 112 of the positive electrode tab 111 is bent so as to stably couple the positive electrode tab to the current interrupt device, the end portion 112 of the positive electrode tab 111 may be coupled to a lower surface of the current interrupt device. That is, the positive electrode tab is not coupled to the central portion of the lower surface of the current interruptive device, but is coupled to the lower surface of the current interruptive device in a state biased to one side. Due to the temperature of the positive electrode tab, which is a main heat generating portion, a portion of the second gasket 135 adjacent to the end portion 112 of the positive electrode tab may melt. In this case, the current interrupt device 134 and the safety vent 132 may be electrically conductive with each other.

Therefore, each of the first and second gaskets may be made of a material having a high melting point and used, however, this causes an increase in manufacturing costs, and thus is difficult to apply.

Patent document 1 relates to a hermetically sealed battery including an inner gasket having convex portions formed on opposite surfaces thereof, in which electrolyte can be inhibited from permeating through a hermetically sealed body, so that a failure of a PTC element or an explosion-proof valve in the hermetically sealed body can be prevented. However, patent document 1 does not disclose a technique capable of preventing the gasket from being melted by heat generated by the cap assembly.

Patent document 2 discloses a structure in which a gasket having a groove formed therein is interposed between a cap assembly serving as a positive electrode terminal and a can serving as a negative electrode terminal in order to insulate the cap assembly and the can from each other. However, patent document 2 does not disclose a structure capable of preventing the gasket of the current interrupt device from melting.

Patent document 3 discloses a structure in which a groove is formed in a gasket interposed between a cap assembly and a battery can in a direction toward the battery can, however, this does not correspond to a technique capable of preventing the heated top cover of the gasket from melting.

Patent document 4 discloses a cylindrical battery cell configured to have the following structure: a groove is formed in the clamping portion of the metal can, i.e., the inner surface of the upper portion of the metal can, and the gasket is partially introduced into the groove by clamping, thereby preventing damage to the gasket during the clamping process.

As described above, there has not been proposed a scheme for preventing damage to the gasket due to high temperature in the cylindrical secondary battery, and therefore, there is a high demand for a technology capable of preventing the gasket from melting using an easy method, thereby improving hermetic sealability and insulation properties.

(prior art document)

- (patent document 1) Japanese patent application laid-open No. 1999-283588 (1999.10.15)

- (patent document 2) Korean patent application laid-open No. 2000-0051436 (2000.08.16)

- (patent document 3) Japanese patent application laid-open No. 2009-135008 (2009.06.18)

- (patent document 4) Korean patent application publication No. 2018-0036086 (2018.04.09)

Disclosure of Invention

Technical problem

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a cylindrical secondary battery including a gasket in which a groove portion is formed, wherein the cylindrical secondary battery is configured to have a structure in which the shape of a first gasket interposed between a top cap and a battery case is modified to minimize contact between a high-temperature portion of the top cap and the first gasket, and the shape of a second gasket located at the outer circumference of a current interruptive device is modified to keep the distance between a high-temperature positive electrode tab and the second gasket maximized.

Technical scheme

In order to achieve the above object, the present invention provides a cylindrical secondary battery comprising: a cylindrical can configured to receive an electrode assembly including a positive electrode, a negative electrode, and a separator; a cap assembly located at an upper portion of the cylindrical can; a first gasket configured to hermetically seal the cylindrical can in a state of being added to cover a peripheral edge of a top cap of the cap assembly and a peripheral edge of a vent member; a Current Interrupt Device (CID) located at a lower portion of the cap assembly; and a second gasket located at a peripheral edge of the current interruptive device, wherein an upper end portion of the first gasket has a structure configured to cover an upper surface of a peripheral edge of the top cap, and a groove portion configured to prevent the first gasket from coming into close contact with the upper surface of the peripheral edge of the top cap is formed in at least a part of an inner surface of the upper end portion of the first gasket.

The top cap may include a bridge portion configured to connect the protruded central portion of the top cap and the outer circumferential edge of the top cap to each other, and the groove portion may be formed in the upper end portion of the first gasket facing the outer circumferential edge of the top cap connected to the bridge portion.

A length connecting opposite ends of the groove portion may be greater than a width of the bridge portion.

The groove portion may be integrally provided with a groove having a uniform depth.

The groove portion may have a structure in which concave portions and convex portions are alternately formed.

A thickness of each of the protrusion portions may be equal to a thickness of the upper end portion of the first gasket, at which the groove portion is not formed.

The thickness of each of the protruding portions may be smaller than the thickness of the upper end portion of the first gasket, at which the groove portion is not formed.

The upper end portion of the first gasket may have a porous structure.

The second gasket may include: an upper portion located at an upper surface of an outer peripheral portion of the current interrupt device, the upper portion configured to prevent contact between the vent member and the current interrupt device; and a side portion located outside an outer circumferential portion of the current interruptive device, and in at least a part of the upper portion, a punched portion may be formed.

The punched portion may be formed at a position adjacent to a positive electrode tab coupled to the current interruptive device.

The punched portion may be formed in a shape in which a portion of an inner side of an upper portion of the second gasket is removed.

The punched portion may have a structure in which a groove is formed in a lower surface of an upper portion of the second gasket.

The groove may be formed in a slit shape.

Drawings

Fig. 1 is a vertical sectional view of a conventional cylindrical secondary battery.

Fig. 2 is a lower perspective view illustrating a positional relationship between the second gasket and the positive electrode tab of fig. 1.

Fig. 3 is a perspective view of the cap assembly.

Fig. 4 is a diagram showing a first embodiment of the first gasket.

Fig. 5 is a diagram showing a second embodiment of the first gasket.

Fig. 6 is a diagram showing a first embodiment of a second gasket.

Fig. 7 is a diagram illustrating a second embodiment of a second gasket.

Detailed Description

Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily implement the preferred embodiments of the present invention. However, in describing in detail the operational principle of the preferred embodiments of the present invention, when a detailed description of known functions and configurations incorporated herein may obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Further, the same reference numerals will be used throughout the drawings to designate portions that perform similar functions or operations. In the case where one portion is referred to as being connected to another portion in the present application, it may be not only that one portion is directly connected to the other portion but also that one portion is indirectly connected to the other portion via another portion. In addition, the inclusion of a certain element does not mean that other elements are excluded, but means that other elements may be further included unless otherwise specified.

Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 3 is a perspective view of the cap assembly.

Referring to fig. 3, the cap assembly is configured to have a structure in which the outer circumferential edge of the top cap 210 is covered with the first gasket 220. The top cover 210 includes: a protruding central portion 211, an opening 213 configured to discharge gas generated in the cylindrical can, and a bridge portion 212 configured to connect the central portion 211 and the outer peripheral edge of the top cover.

The positive electrode tab is coupled to a lower surface of the current interruptive device located at the lower end of the cap assembly. The positive electrode tab is a path through which current flows, and particularly, the electrode tab is an excessively heated portion.

As a result, the temperature of the entire cap assembly connected to the positive electrode tab is increased. In particular, in the first gasket 220, the upper end portion of the first gasket 220 facing the outer circumferential edge of the cap connected to the bridge portion 212 of the cap exhibits the highest temperature distribution.

Accordingly, the present invention proposes a structure capable of minimizing contact between the peripheral edge of the top cap and the first gasket, thereby suppressing high temperature of the bridge portion from being transferred to the first gasket, thereby preventing the first gasket from being melted.

In connection with this, fig. 4 is a diagram showing a first embodiment of the first gasket, and fig. 5 is a diagram showing a second embodiment of the first gasket.

Referring to fig. 4, the first gasket 230 has a structure in which a groove portion 232 is formed in an inner surface of an upper end portion 231 of the first gasket.

Specifically, the groove portion 232 is formed in the upper end portion 231 of the first gasket facing the outer peripheral edge of the top cap connected to the bridge portion of the top cap.

At the upper end portion of the first gasket, the groove portions 232 may be formed to have a uniform thickness, and the same number of groove portions 232 as the number of bridge portions formed on the top cap may be formed.

At the upper end portion of the first gasket, the thickness of the groove portion 232 is smaller than that of a portion of the first gasket where the groove portion is not formed, thereby forming a space spaced apart from the upper surface of the top cover in the groove portion 232 of the first gasket.

Preferably, the groove portion 232 has a size greater than that of an outer circumferential edge of the top cap connected with the bridge portion, wherein a length a1 of the packing 230 connecting opposite ends of the groove portion 232 may be greater than a width a2 of the bridge portion 212 of fig. 3.

Referring to fig. 5, the first gasket 240 has a structure in which a groove portion 242 is formed in an inner surface of an upper end portion 241 of the first gasket.

Like the first gasket 230 of fig. 4, the groove portion 242 of the first gasket 240 is formed in the inner surface of the upper end portion of the first gasket facing the outer peripheral edge of the top cap connected to the bridge portion of the top cap.

The groove portion 242 has a structure in which concave portions 242a and convex portions 242b are alternately formed. In the case where the thickness d2 of each convex portion 242b is equal to the thickness dl of the upper end portion of the first gasket, where the groove portion is not formed, the concave portion 242a of the groove portion is not in close contact with the upper surface of the outer peripheral edge of the top cap connected to the bridge portion, but the convex portion 242b of the groove portion is in close contact with the upper surface of the outer peripheral edge of the top cap connected to the bridge portion.

As described above, the contact point between the high temperature portion of the cap assembly and the first gasket may be partially removed, whereby damage to the first gasket due to the high temperature transferred to the first gasket may be suppressed.

Alternatively, in the case where the thickness d2 of each protrusion portion 242b is less than the thickness d1 of the upper end portion of the first gasket, where the groove portion is not formed, the entire groove portion is configured to be spaced apart from the upper surface of the outer peripheral edge of the top cap connected to the bridge portion, whereby the high temperature transferred to the first gasket can be minimized.

Alternatively, the upper end portion 231 or 241 of the first gasket 230 or 240 may have a porous structure in order to minimize the high temperature transferred to the first gasket, and the side portion 233 or 243 of the first gasket 230 or 240 may have a high-density structure in order to hermetically seal the cylindrical can.

Generally, a second gasket is located at an outer circumferential edge of the current interruptive device disposed at a lower portion of the cap assembly, the second gasket serving to maintain insulation between the current interruptive device and the safety vent when the current interruptive device and the safety vent are separated from each other.

The positive electrode tab of the electrode assembly is attached to the lower surface of the current interrupt device, and the positive electrode tab is attached to a position offset to one side from the center of the current interrupt device. Therefore, the portion of the second gasket adjacent to the positive electrode tab exhibits the highest temperature distribution.

In connection with this, fig. 6 is a diagram showing a first embodiment of the second gasket, and fig. 7 is a diagram showing a second embodiment of the second gasket.

Referring to fig. 6, the second gasket 350 includes: a second gasket upper part 351, the second gasket upper part 351 being located at an upper surface of an outer circumferential part of the current interruptive device so as to prevent contact between the vent member and the current interruptive device; and a second gasket side portion 352, the second gasket side portion 352 being located outside an outer circumferential portion of the current interruptive device, wherein a punched portion 353 is formed in at least a portion of the second gasket upper portion 351.

In fig. 6, a positive electrode tab 111 that is extended to be attached to the lower surface of the current interrupt device is shown by a dotted line. A part of the inner side of the second gasket upper part 351 is removed by punching at a position adjacent to the end 112 of the positive electrode tab coupled to the current interruptive device, thereby forming a punched part 353.

Preferably, the punched portion 353 is formed to have a size required to secure a distance from the positive electrode tab 111 and is located at a position required to secure a distance from the positive electrode tab 111. Preferably, the length c1 connecting the opposite ends of the punched part is greater than the width c2 of the positive electrode tab.

Accordingly, the distance between the end portion 112 of the positive electrode tab 111 and the second gasket 350 may be maximized.

Referring to fig. 7, the second gasket 360 includes: a second gasket upper part 361, the second gasket upper part 361 being located at an upper surface of an outer circumferential portion of the current interruptive device so as to prevent contact between the vent member and the current interruptive device; and a second pad side portion 362, the second pad side portion 362 being located outside an outer circumferential portion of the current interruptive device, wherein a stamped-out portion 363 is formed in at least a portion of the second pad upper portion 361.

The stamped part 363 has a structure in which a groove is formed in the lower surface of the second gasket upper part 361, wherein the groove is formed in a slit shape. Alternatively, in another embodiment, the stamped portion may have a through hole formed therein.

Accordingly, in the case where the safety vent is deformed due to the increase in the internal pressure of the cylindrical secondary battery, and thus the safety vent coupled to the current interrupt device is separated from the current interrupt device, it is possible to suppress damage to the second gasket due to high heat transferred to the positive electrode tab of the second gasket while ensuring insulation between the safety vent and the current interrupt device.

In the same manner as the stamped part 353 of fig. 6, a stamped part 363 is also formed in the upper part of the second gasket adjacent to the end 112 of the positive electrode tab, and the length connecting the opposite ends of the stamped part is greater than the width of the positive electrode tab.

For reference, for each of the positive electrode tabs shown in fig. 6 and 7, an end of the positive electrode tab opposite to the end 112 of the positive electrode tab coupled to the current interruptive device is a portion connected to the electrode assembly and positioned to be spaced apart from the cap assembly. Therefore, unlike shown in the drawings, the opposite end portion of the positive electrode tab is not positioned adjacent to the second gasket.

As described above, the present invention provides a cylindrical secondary battery configured such that a first gasket and a second gasket are applied in a state in which the shape of each of the first gasket and the second gasket is modified, thereby improving the resistance of the cylindrical secondary battery to high temperatures while ensuring the hermetic sealing property and the insulation property of the cylindrical secondary battery.

Those skilled in the art to which the invention pertains will appreciate that various applications and modifications can be made based on the above description without departing from the scope of the invention.

(reference mark explanation)

100: cylindrical secondary battery

110: jelly roll type electrode assembly

111: positive electrode tab

112: end of positive electrode tab

120: cylindrical battery shell

130: cap assembly

131. 210: top cover

132: safety ventilation piece

133. 220, 230, 240: first liner

134: current interruption device

135. 350 and 360: second liner

211: center part

212: bridge part

213: opening of the container

231. 241: the upper end of the first gasket

232. 242: trough part

233. 243, and (3) a step of: side part of the first pad

242 a: concave part

242 b: projecting part

351. 361: upper part of the second gasket

352. 362: second liner side

353. 363: stamped part

a 1: length of opposite ends of the connecting groove portion

a 2: width of bridge part

c 1: length connecting opposite ends of the stamped part

c 2: width of positive electrode tab

d 1: thickness of upper end part of first liner without groove part

d 2: the thickness of the protruding portion.

Industrial applicability

As is apparent from the above description, the cylindrical secondary battery according to the present invention is configured such that the groove portion is formed in the first gasket, thereby forming a portion in which the top cap, which is a high-temperature portion, and the first gasket are not in close contact with each other. Therefore, melting of the first gasket due to heat generation of the top cover can be minimized.

Further, the punched portion is formed in the second gasket, whereby the distance between the second gasket and the positive electrode tab can be kept maximized. Therefore, the melting of the second gasket due to the heat generation of the positive electrode tab can be minimized.

As described above, the resistance of the cylindrical secondary battery to high temperature may be improved using a method of modifying the shape of each of the first and second gaskets. Therefore, an additional process for securing high temperature resistance of the cylindrical secondary battery is not required, and thus the present invention can be easily applied to a process for manufacturing a conventional cylindrical secondary battery.

In addition, an expensive heat-resistant material is not used, whereby the manufacturing cost can be reduced.