阅读说明：本技术 包括正极接片固定构件的圆柱形二次电池 (Cylindrical secondary battery including positive electrode tab fixing member ) 是由 都珍旭 于 2020-06-26 设计创作，主要内容包括：公开了一种圆柱形二次电池,包括：电极组件,电极组件具有正极片和负极片在它们之间插置有隔膜的状态下被卷绕的结构；配置为容纳电极组件的圆柱形罐；以及安装至圆柱形罐的敞开的上端的盖组件,其中盖组件包括：位于盖组件的上部的顶盖,顶盖具有突出结构；通气构件,通气构件在包裹顶盖的外周边缘的同时位于顶盖的下部,通气构件向下凹陷；以及衬垫,衬垫配置为气密地密封圆柱形罐,电极组件的正极接片直接结合至通气构件的下表面,并且圆柱形二次电池进一步包括配置为固定正极接片的位置的绝缘的固定构件。(Disclosed is a cylindrical secondary battery comprising: an electrode assembly having a structure in which a positive electrode tab and a negative electrode tab are wound with a separator interposed therebetween; a cylindrical can configured to receive the electrode assembly; and a cap assembly mounted to the open upper end of the cylindrical can, wherein the cap assembly includes: a top cap positioned at an upper portion of the cap assembly, the top cap having a protruding structure; a vent member located at a lower portion of the top cover while wrapping a peripheral edge of the top cover, the vent member being downwardly recessed; and a gasket configured to hermetically seal the cylindrical can, the positive electrode tab of the electrode assembly is directly bonded to a lower surface of the vent member, and the cylindrical secondary battery further includes an insulating fixing member configured to fix a position of the positive electrode tab.)

1. A cylindrical secondary battery comprising:

an electrode assembly including a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet, the negative electrode sheet, and the separator being wound;

a cylindrical can configured to receive the electrode assembly; and

a cap assembly mounted to the open upper end of the cylindrical can, wherein

The cap assembly includes: a top cap positioned at an upper portion of the cap assembly, the top cap having a protruding structure; a vent member located at a lower portion of the top cap while wrapping around a peripheral edge of the top cap, the vent member being downwardly recessed; and a gasket configured to hermetically seal the cylindrical can,

the positive electrode tab of the electrode assembly is directly bonded to the lower surface of the vent member, and

the cylindrical secondary battery further includes an insulating fixing member configured to fix a position of the positive electrode tab.

2. The cylindrical secondary battery according to claim 1, wherein

The positive electrode tab includes a positive electrode tab main body, and a coupling part bent from one end of the positive electrode tab main body, the coupling part being coupled to the lower surface of the vent member, and

the fixing member is interposed between the positive electrode tab main body and the junction.

3. The cylindrical secondary battery according to claim 2, wherein the fixing member is adhered to the bonding part at a surface of the fixing member facing the bonding part.

4. The cylindrical secondary battery according to claim 3, wherein a bonding force between the fixing member and the bonding part is higher than a bonding force between the bonding part and the vent member.

5. The cylindrical secondary battery according to claim 1, wherein the fixing member is located at a lower portion of the gasket.

6. The cylindrical secondary battery according to claim 5, wherein the fixing member is coupled to the gasket by being engaged with the gasket.

7. The cylindrical secondary battery according to claim 1, wherein the fixing member is formed in a fan shape or a bar shape when viewed in a plan view.

8. The cylindrical secondary battery according to claim 1, wherein the fixing member is integrally combined with an upper insulating plate between the electrode assembly and the cap assembly.

9. The cylindrical secondary battery according to claim 8, wherein the fixing member extends upward from the outer circumferential portion of the upper insulating plate, is bent toward the central portion of the upper insulating plate, and is disposed parallel to the upper insulating plate.

10. A method of manufacturing the cylindrical secondary battery according to any one of claims 1 to 9, the method comprising the steps of:

accommodating an electrode assembly in a cylindrical can, the electrode assembly including a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet, the negative electrode sheet, and the separator being wound;

positioning an upper insulating plate at an upper portion of the electrode assembly;

forming a crimping part;

bonding a positive electrode tab of the electrode assembly to a lower surface of a vent member constituting a cap assembly;

bonding a fixing member to a gasket constituting the cap assembly; and

bonding the cap assembly to the cylindrical can and crimping the cylindrical can.

11. The method of claim 10, wherein the step of bonding the fixation member to the pad comprises: and bonding the bonding portion of the positive electrode tab and the fixing member to each other.

12. A method of manufacturing the cylindrical secondary battery according to any one of claims 1 to 9, the method comprising the steps of:

accommodating an electrode assembly in a cylindrical can, the electrode assembly including a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet, the negative electrode sheet, and the separator being wound;

positioning an upper insulating plate at an upper portion of the electrode assembly;

forming a crimping part;

a positive electrode tab of the electrode assembly is bonded to a lower surface of a vent member constituting a cap assembly;

fixing the positive electrode tab to a fixing member integrally combined with the upper insulating plate; and

bonding the cap assembly to the cylindrical can and crimping the cylindrical can.

13. The method of claim 12, wherein the step of securing the positive electrode tab comprises: extending the positive electrode tab through a lower surface of the fixing member, bending the positive electrode tab, and attaching the positive electrode tab to an upper surface of the fixing member.

Technical Field

This application claims the benefit of priority from korean patent application No. 2019-0077738, filed on 28.6.2019, the entire disclosure of which is incorporated herein by reference.

The present invention relates to a cylindrical secondary battery including a positive electrode tab fixing member, and more particularly, to a cylindrical secondary battery configured to omit a current interrupt device from a cap assembly, to which a positive electrode tab is directly coupled to a vent member, and including a fixing member configured to fix the positive electrode tab.

Background

Based on the shape of the battery case, 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 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 a cap assembly is located at an open upper end of a 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. The gasket also has a function of ensuring insulation between the cap assembly connected to the positive electrode tab of the electrode assembly and the cylindrical case connected to the negative electrode tab of the electrode assembly.

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

The cap assembly 130 includes a vent member 132 and a current interrupt device 135, the vent member 132 being located at a lower portion of the cap cover in a state of surrounding an outer circumference of the cap cover 131, and the current interrupt device 135 being located below the vent member 123 in a state of contacting a central portion of the vent member 132. The lower gasket 134 is located at the outer peripheral edge of the current interruptive device 135, and the lower gasket 134 is configured to prevent the vent member 132 and the current interruptive device 135 from contacting each other at portions other than the central portion of the vent member.

The positive electrode tab 111 of the electrode assembly 110 is attached to the lower surface of the current interruptive device 135 so that the cap assembly 130 serves as a positive electrode terminal.

As described above, the cap assembly of the cylindrical secondary battery includes the top cap, the vent member, the crimping gasket, the current interrupt device, and the lower gasket, wherein the pressure at which a short circuit occurs in the secondary battery is reduced due to the deformation of the vent member.

Further, in the case of reducing the overall height of the cap assembly while the components of the cap assembly remain unchanged, there is insufficient space for the vent member to deform, so that the vent member deforms slowly. As a result, it is difficult to specify the point of time at which the short circuit occurs. Further, the gas discharge path becomes narrow, which becomes an obstacle to gas discharge.

In connection with this, patent document 1 relates to a cap assembly configured to have a structure in which a positive electrode tab of an electrode assembly and a safety vent are welded to each other, when internal pressure is increased due to generation of gas, a welded portion between the safety vent and the positive electrode tab is broken, so that a short circuit occurs, and the positive electrode tab is fixed by a gasket.

In patent document 1, the positive electrode tab is fixed to the safety vent, thereby achieving structural simplification. However, the positive electrode tab must be attached to cross the central portion of the gasket so that the positive electrode tab is fixed by the gasket, and the gasket is used in a deformed shape.

Patent document 2 relates to a secondary battery configured such that an electrode tab, which is provided with a notch and is attached to a lower portion of a safety vent, electrically connects an electrode assembly and a cap assembly to each other, wherein the notch is cut off when a current equal to or higher than a reference current flows.

Patent document 3 relates to a secondary battery assembly configured such that a mesh-like metal grid having high conductivity is located on the upper side of an electrode assembly, wherein the secondary battery assembly includes: a positive electrode grid configured to contact the positive electrode, and a conductive positive electrode current collector plate configured to support the positive electrode grid. The number of contact points between the electrode and the current collector is increased, so that contact resistance can be reduced.

Each of patent document 2 and patent document 3 can provide a battery cell having improved safety, but a method of increasing the capacity of the battery cell even when the structure of the battery cell is changed is not proposed.

Therefore, there is a high necessity for a cylindrical secondary battery configured to have a structure in which a short circuit stably occurs while reducing the overall height of a cap assembly, thereby increasing the battery capacity.

(Prior art document)

(patent document 1) Korean patent application laid-open No. 2018-0005455 (2018.01.16)

(patent document 2) Korean patent application laid-open No. 2014-0082270 (2014.07.02)

(patent document 3) Korean patent application laid-open No. 2000-0026860 (2000.05.15)

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 having a stable structure in which the configuration of a cap assembly is simplified to increase the capacity of the battery, and when the internal pressure of the secondary battery is increased due to gas generated in the secondary battery, a vent member is easily separated from a positive electrode tab to easily achieve gas discharge.

Technical scheme

In order to achieve the above object, a cylindrical secondary battery according to the present invention includes: an electrode assembly having a structure in which a positive electrode tab and a negative electrode tab are wound with a separator interposed therebetween; a cylindrical can configured to receive the electrode assembly; and a cap assembly mounted to the open upper end of the cylindrical can, wherein the cap assembly includes: a top cap positioned at an upper portion of the cap assembly, the top cap having a protruding structure; a vent member located at a lower portion of the top cap while wrapping around a peripheral edge of the top cap, the vent member being downwardly recessed; and a gasket configured to hermetically seal the cylindrical can, a positive electrode tab of the electrode assembly is directly bonded to a lower surface of the vent member, and the cylindrical secondary battery further includes an insulating fixing member configured to fix a position of the positive electrode tab.

The positive electrode tab may include a positive electrode tab main body, and a bonding part bent from one end of the positive electrode tab main body, the bonding part being bonded to the lower surface of the vent member, and the fixing member may be interposed between the positive electrode tab main body and the bonding part.

The fixing member may be adhered to the bonding portion at a surface of the fixing member facing the bonding portion.

A coupling force between the fixing member and the coupling portion may be higher than a coupling force between the coupling portion and the vent member.

The fixing member may be located at a lower portion of the pad.

The securing member may be coupled to the pad by engaging with the pad.

The fixing member may be formed in a fan shape or a bar shape when viewed in a plan view.

The fixing member may be integrally combined with an upper insulating plate between the electrode assembly and the cap assembly.

The fixing member may extend upward from an outer circumferential portion of the upper insulating plate, may be bent toward a central portion of the upper insulating plate, and may be disposed parallel to the upper insulating plate.

The present invention provides a method of manufacturing a cylindrical secondary battery according to an embodiment, the method including the steps of: accommodating an electrode assembly in a cylindrical can, the electrode assembly having a structure in which a positive electrode tab and a negative electrode tab are wound with a separator interposed therebetween; positioning an upper insulating plate at an upper portion of the electrode assembly; forming a crimping part; bonding a positive electrode tab of the electrode assembly to a lower surface of a vent member constituting a cap assembly; bonding a fixing member to a gasket constituting the cap assembly; and bonding the cap assembly to the cylindrical can and crimping the cylindrical can.

The step of bonding the fixing member to the pad may include: and bonding the bonding portion of the positive electrode tab and the fixing member to each other.

The present invention also provides a method of manufacturing a cylindrical secondary battery according to another embodiment, the method including the steps of: accommodating an electrode assembly in a cylindrical can, the electrode assembly having a structure in which a positive electrode tab and a negative electrode tab are wound with a separator interposed therebetween; positioning an upper insulating plate at an upper portion of the electrode assembly; forming a crimping part; a positive electrode tab of the electrode assembly is bonded to a lower surface of a vent member constituting a cap assembly; fixing the positive electrode tab to a fixing member integrally combined with the upper insulating plate; and bonding the cap assembly to the cylindrical can and crimping the cylindrical can.

The step of fixing the positive electrode tab may include: extending the positive electrode tab through a lower surface of the fixing member, bending the positive electrode tab, and attaching the positive electrode tab to an upper surface of the fixing member.

Drawings

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

Fig. 2 is a vertical sectional view of a cylindrical secondary battery according to an embodiment.

Fig. 3 is an enlarged view of the upper portion of fig. 1 and 2.

Fig. 4 is a diagram illustrating a part of a process of manufacturing a cylindrical secondary battery.

Fig. 5 is a view illustrating a state in which a fixing member is coupled to the cylindrical secondary battery of fig. 4.

FIG. 6 is a perspective view of a fixation member according to an embodiment.

Fig. 7 is a perspective view of an upper insulating plate incorporating a fixing member according to an embodiment.

Detailed Description

Now, 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 preferred embodiments of the present invention. However, in describing in detail the operation principle of the preferred embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention.

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. 2 is a vertical sectional view of a cylindrical secondary battery according to an embodiment.

Referring to fig. 2, the cylindrical secondary battery 200 is configured such that: the electrode assembly 210 is received in the cylindrical can 220, the cap assembly 230 is located at the upper portion of the cylindrical can 220, and the cylindrical secondary battery 200 is hermetically sealed by the gasket 233.

The cap assembly 230 includes: a top cover 231 having an upwardly protruding central portion; a vent member 232, the vent member 232 being located at a lower portion of the top cap 231 while wrapping the outer circumferential edge of the top cap 231, the vent member 232 being downwardly recessed; and a gasket 233, the gasket 233 being configured to hermetically seal the secondary battery in a state of being in contact with the cylindrical can 220.

That is, the cap assembly 230 according to the present invention does not include a current interrupt device included in a cap assembly applied to a conventional cylindrical secondary battery and a gasket added to the outer circumferential edge of the current interrupt device.

Therefore, in the cylindrical secondary battery 200 according to the present invention, the positive electrode tab 211 is directly bonded to the lower surface of the vent member 232.

However, in the case where the vent member is deformed into an inverted shape due to an increase in internal pressure of the cylindrical secondary battery, the vent member must be separated from the positive electrode tab so that a short circuit occurs. For this, a fixing member 240 configured to fix the position of the positive electrode tab 211 is added.

Specifically, the lower end of the positive electrode tab is attached to the electrode assembly, and the upper end of the positive electrode tab is bonded to the lower surface of the vent member. The positive electrode tab may include a positive electrode tab main body 211a and a coupling part 211b coupled to a lower surface of the vent member.

The junction 211b is a portion bent and then extended from the upper end of the positive electrode tab main body 211 a. The coupling portion 211b and the positive electrode tab main body 211a are positioned to face each other, and the fixing member 240 is located between the coupling portion 211b and the positive electrode tab main body 211 a. Therefore, when the vent member 232 is separated from the positive electrode tab, the position of the positive electrode tab is fixed so that the positive electrode tab does not move.

The separation of the positive electrode tab main body 211a may be prevented by the fixing member 240. However, in order to prevent the coupling portion 211b coupled with the vent member 232 from moving upward together with the vent member 232, the fixing member 240 and the coupling portion 211b may be adhered to each other at surfaces thereof facing each other.

That is, the upper surface of the combining portion 211b is combined to the venting member 232, and the lower surface of the combining portion 211b is combined to the fixing member 240. However, when the vent member 232 is deformed and separated from the coupling portion 211b, the coupling between the coupling portion 211b and the fixing member 240 must be maintained. Therefore, it is preferable that the coupling force between the coupling portion 211b and the fixing member 240 is higher than the coupling force between the coupling portion 211b and the venting member 232.

As described above, since some components constituting the conventional cap assembly are omitted, the overall height of the cap assembly is reduced. Therefore, when comparing the capacities of the battery cells in the cylindrical secondary batteries having the same length, the cylindrical secondary battery according to the present invention can secure a larger electrode assembly receiving space, so that a high-capacity secondary battery can be provided.

In this regard, fig. 3 is an enlarged view of the upper portion of fig. 1 and 2.

Referring to fig. 3, the upper portion of the cylindrical secondary battery 100 of fig. 1 and the upper portion of the cylindrical secondary battery 200 of fig. 2 are shown side by side, whereby components of a cap assembly and the overall height of the cap assembly may be compared and a change in the size of a space in which a vent member is deformed may be confirmed.

Specifically, the cylindrical secondary battery 200 according to the present invention has a structure in which the lower gasket 134 and the current interruptive device 135 are omitted from the conventional cylindrical secondary battery 100.

In addition, the distance between the top cap 231 of the cylindrical secondary battery 200 according to the present invention and the venting member 232 is greater than the distance between the top cap 131 and the venting member 132 of the conventional cylindrical secondary battery 100.

Generally, in order to increase the capacity of the battery cell, the overall height of the cap assembly is reduced, so that the distance between the top cap and the vent member is designed to be short. As a result, even if a short circuit needs to be caused due to sudden deformation of the vent member when the internal pressure of the battery cell increases, the vent member is slowly deformed, so that it is difficult to specify a point of time when the short circuit occurs.

In the present invention, as shown in fig. 3, the distance between the top cover and the vent member is designed to be increased, so that the above-mentioned problems can be solved.

Further, in the cylindrical secondary battery 200 according to the present invention, the overall height of the cap assembly is reduced as compared to the conventional cylindrical secondary battery 100, so that the object of the present invention for manufacturing a high-capacity secondary battery can be achieved.

The method of manufacturing the cylindrical secondary battery 200 according to the present invention may include the steps of: accommodating an electrode assembly in the cylindrical can, the electrode assembly having a structure in which a positive electrode tab and a negative electrode tab are wound with a separator interposed therebetween; positioning an upper insulating plate at an upper portion of the electrode assembly; forming a crimping part; bonding a positive electrode tab of the electrode assembly to a lower surface of a vent member constituting the cap assembly; bonding the fixing member to a gasket constituting a cap assembly; and bonding the cap assembly to the cylindrical can and crimping the cylindrical can.

Further, the step of bonding the fixing member to the gasket may include the step of bonding the bonding portion of the positive electrode tab and the fixing member to each other.

In connection with this, fig. 4 is a view illustrating a part of a process of manufacturing a cylindrical secondary battery, and fig. 5 is a view illustrating a state in which a fixing member is coupled to the cylindrical secondary battery of fig. 4.

Referring to fig. 4 and 5, the electrode assembly 210 is received in the cylindrical can 220, the upper insulating plate 250 is located at an upper portion of the electrode assembly, and the beading part 260 is formed at an upper portion of the upper insulating plate 250.

In a state where the cap assembly 230 is assembled, the positive electrode tab 211 attached to the electrode assembly 210 is attached to the lower surface of the vent member 232. One surface of the positive electrode tab 211 is bonded to the vent member 232, and the other surface of the positive electrode tab 211 is bonded to the fixing member 240. The cap assembly 230 is coupled to the upper portion of the cylindrical can 220 in a state of being coupled with the positive electrode tab 211 and the fixing member 240, and crimps the cylindrical can 220.

The fixing member 240 may be located at a lower portion of the pad 233, and one end of the fixing member 240 overlapping the pad 233 may be coupled to the pad 233 by being engaged with the pad 233.

In a specific example, the fixing member 240 may be formed in a fan shape or a bar shape when viewed in a plan view.

In connection therewith, fig. 6 is a perspective view of a fixation member according to an embodiment.

Referring to fig. 6, the fixing member 241 is formed in a bar shape when viewed in a plan view, and the fixing member 241 includes: a rectangular base portion 241a configured to fix the positive electrode tab, and an engaging portion 241b configured to be coupled to the gasket by engaging with the gasket. In the case of using such a small fixing member 241, an increase in weight of the cylindrical secondary battery due to the addition of the fixing member can be minimized.

In addition, the fixing member 242 is formed in a fan shape, such as a semicircle, when viewed in a plan view, and the fixing member 242 includes: a semicircular base portion 242a configured to fix the positive electrode tab, and an engagement portion 242b configured to be coupled to the gasket by engaging with the gasket. In the case of using a fixing member including a large base portion, such as the fixing member 242, there is almost no limitation in setting the position of the fixing member based on the extended position of the positive electrode tab, and even in the case of including a plurality of positive electrode tabs, the positive electrode tab can be stably fixed.

In addition, a shape in which a fixing member is integrally added to a conventional battery cell part may be further suggested. For example, the fixing member may be integrally combined with the upper insulating plate between the electrode assembly and the cap assembly. Specifically, the fixing member may extend upward from the outer circumferential portion of the upper insulating plate, may be bent toward the central portion of the upper insulating plate, and may be disposed parallel to the upper insulating plate.

In connection with this, fig. 7 is a perspective view of an upper insulating plate incorporating a fixing member according to an embodiment.

Referring to fig. 7, a fixing member 243 integrally coupled with the upper insulating plate 251 is added to an outer circumferential portion of an upper surface of the upper insulating plate 251. The fixing member 243 extends vertically upward from the plane of the upper insulating plate 251, is bent by 90 degrees, and is positioned parallel to the upper insulating plate.

The upper insulating plate 251 is provided with a plurality of through-holes, through one of which the positive electrode tab 211 attached to the electrode assembly to extend upward from the electrode assembly extends. The positive electrode tab 211 extends through an overlapping portion between the fixing member 243 and the upper insulating plate 251 after extending through one of the plurality of through-holes, is bent 180 degrees, and is coupled to the upper surface of the fixing member 243.

However, the positive electrode tab 211 may be located between the fixing member and the upper insulating plate in a state of being coupled to the lower surface of the vent member. The method of manufacturing the cylindrical secondary battery using the fixing member 243 may include the steps of: accommodating an electrode assembly in the cylindrical can, the electrode assembly having a structure in which a positive electrode tab and a negative electrode tab are wound with a separator interposed therebetween; positioning an upper insulating plate at an upper portion of the electrode assembly; forming a crimping part; bonding a positive electrode tab of the electrode assembly to a lower surface of a vent member constituting the cap assembly; fixing the positive electrode tab to a fixing member integrally combined with the upper insulating plate; and bonding the cap assembly to the cylindrical can and crimping the cylindrical can.

As described above, in the present invention, the fixing member is included such that the positive electrode tab is completely separated from the vent when the vent is deformed, thereby causing a short circuit, a larger space in which the vent can be deformed is secured, such that the short circuit can be stably caused, and the overall height of the cap assembly is reduced, thereby providing a high-capacity 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 number description)

100. 200: cylindrical secondary battery

110. 210: electrode assembly

111. 211: positive electrode tab

120. 220, and (2) a step of: cylindrical tank

130. 230: cap assembly

131. 231: top cover

132. 232: ventilation member

133: crimping gasket

134: lower liner

135: current interruption device

211 a: positive electrode tab main body

211 b: joining part

233: liner pad

240. 241, 242, 243: fixing member

241a, 242 a: base part

241b, 242 b: engaging part

250. 251: upper insulating plate

260: and (4) curling edge parts.

Industrial applicability

As apparent from the above description, a cylindrical secondary battery according to the present invention includes a cap assembly in which a current interrupt device and a gasket added to the outer circumferential edge of the current interrupt device are omitted, wherein the overall height of the cap assembly is reduced, thereby securing a larger space occupied by the electrode assembly, and thus a secondary battery having an increased capacity can be provided.

Further, the positive electrode tab attached to the vent member may be stably fixed using the fixing member, so that when the vent member is deformed due to an increase in internal pressure of the secondary battery, the vent member is separated from the fixed positive electrode tab, and thus the flow of current may be interrupted.