Secondary battery and method for manufacturing same

Abstract

One embodiment of the present disclosure relates to a secondary battery and a method of manufacturing the same, the secondary battery including: a cylindrical can including a circular bottom portion and a side portion extending from the circular bottom portion, the side portion having an open end portion; an electrode assembly accommodated in the cylindrical can; a current interruption device disposed in the open end portion of the side portion and having an exhaust port therein; and a pad disposed between the side portion and the current interruption device and including a protrusion configured to support a lower portion of the current interruption device. According to an embodiment of the present disclosure, by improving the shape of the gasket, components such as an upper cap and a safety vent will not deform due to pressure when forming a crimped portion and a crimped portion on a can for assembling the cap assembly. Therefore, the stability of the secondary battery can be improved.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority and benefit of Korean Patent Application No. 10 - 2024 - 0012970, filed with the Korean Intellectual Property Office on January 29, 2024, the entire contents of which are incorporated herein by reference. Technical field

[0003] One embodiment of the present disclosure relates to a secondary battery having an improved structure of a cover assembly. Background art

[0004] Generally, a cylindrical secondary battery includes a cylindrical electrode assembly, a cylindrical can configured to accommodate the electrode assembly and an electrolyte, and a cover assembly coupled to an upper opening of the can to seal the can and allow current generated in the electrode assembly to flow to an external device.

[0005] A crimping part is formed on an upper part of the can, the cover assembly is disposed on the crimping part, and a crimping portion is formed to fix the cover assembly, thereby fixing the cover assembly to the can. Thus, the cover assembly includes a gasket for insulating from the can. However, the pressure applied to the cover assembly during the formation of the crimping part may cause the upper cover to be compressed and deformed, resulting in deformation of the upper cover and the safety vent.

[0006] The above - mentioned information disclosed in the technology used as the background art of the present disclosure is only for enhancing the understanding of the background art of the present disclosure, and thus may include information that does not constitute related art. Summary of the invention

[0007] The present disclosure aims to provide a secondary battery having an improved structure of a cover assembly, which prevents component deformation during the assembly of the cover assembly.

[0008] A secondary battery according to an embodiment of the present disclosure includes: a cylindrical can including a circular bottom and a side portion extending from the circular bottom, the side portion having an open end portion; an electrode assembly accommodated in the cylindrical can; a current interruption device disposed in the open end portion of the side portion and having an exhaust port in the current interruption device; and a gasket disposed between the side portion and the current interruption device and including a protrusion configured to support a lower portion of the current interruption device.

[0009] The gasket may include an insulating material.

[0010] The cross - sectional shape of the protrusion may be any one of a triangular shape, a streamline shape, a semi - circular shape, a semi - elliptical shape, and a polygonal shape.

[0011] The highest point of the protrusion may contact a preset point of the current interruption device.

[0012] The side portion may include a crimping portion adjacent to one end of the side portion and having an inwardly concave shape, and a crimping portion including the inwardly bent end portion of the side portion.

[0013] The upper portion of the gasket may be disposed between the crimping portion and the current interruption device, and the lower portion of the gasket may be disposed between the current interruption device and the crimping portion. A protrusion may protrude from the upper surface of the lower portion of the gasket.

[0014] The highest point of the protrusion may be set closer to the center of the cylindrical can in the diameter direction of the cylindrical can than the end portion of the crimping portion.

[0015] When the cross section of the protrusion has a triangular shape or a streamline shape, the angle of the upwardly convex inclined surface of the protrusion with respect to the lower surface of the lower portion of the gasket may be in the range of 7° to 14°.

[0016] Furthermore, a secondary battery according to an embodiment of the present disclosure includes: a cylindrical can including a circular bottom, a side portion extending from the circular bottom, a crimping portion having a concave shape at one end of the side portion, and a crimping portion including the bent end portion of the side portion; an electrode assembly accommodated in the cylindrical can; a lid assembly configured to seal the cylindrical can and including a gasket configured to be insulated from the cylindrical can; and a current interruption device, wherein the gasket includes an annular body, a connecting portion extending from the annular body, an extending portion extending downward from the connecting portion, and a protrusion protruding upward from the connecting portion to support the lower portion of the current interruption device.

[0017] The gasket may include an insulating material.

[0018] The cross-sectional shape of the protrusion may be any one of a triangular shape, a streamline shape, a semi-circular shape, a semi-elliptical shape, and a polygonal shape.

[0019] The gasket may have a shape in which the thickness of the annular body decreases toward the end portion of the gasket.

[0020] The connecting portion of the gasket is bent and may extend from the annular body at a predetermined angle, and the protrusion may protrude from the upper surface of the connecting portion.

[0021] The annular body of the gasket may be disposed between the crimping portion and the current interruption device, and the connecting portion of the gasket may be disposed between the current interruption device and the crimping portion.

[0022] The highest point of the protrusion may be set closer to the center of the cylindrical can in the diameter direction of the cylindrical can than the end portion of the crimping portion.

[0023] The protrusion includes a first inclined surface protruding upward and a second inclined surface extending downward and inclining from the first inclined surface. When the protrusion has a triangular cross-section or a streamline cross-section, the angle between the first inclined surface and the lower surface of the connecting portion can be in the range of 7° to 14°.

[0024] Furthermore, a method of manufacturing a secondary battery according to an embodiment of the present disclosure includes: forming a cylindrical can including a circular bottom, a side portion extending from the circular bottom, a crimping portion, and a caulking portion, wherein the crimping portion is recessedly formed at one end of the side portion and the caulking portion is formed by bending an end portion of the side portion; accommodating an electrode assembly in the cylindrical can; accommodating a current interruption device in the cylindrical can; and sealing the cylindrical can with a lid assembly including a gasket insulated from the cylindrical can, wherein the gasket includes an annular body, a connecting portion extending from the annular body, an extending portion extending downward from the connecting portion, and a protrusion protruding upward from the connecting portion, and the method further includes supporting a lower portion of the current interruption device with the protrusion.

[0025] The method may further include forming the gasket into a shape in which the thickness of the annular body decreases toward an end portion of the gasket.

[0026] Forming the gasket may include: bending the connecting portion of the gasket at a predetermined angle to extend from the annular body, and forming the protrusion to protrude from an upper surface of the connecting portion.

[0027] The method may further include: positioning an upper portion of the gasket between the caulking portion and the current interruption device, and positioning a lower portion of the gasket between the current interruption device and the crimping portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1A is a longitudinal sectional view illustrating a general cylindrical secondary battery.

[0029] Figure 1B is according to Figure 1A an enlarged sectional view of a part of the lid assembly.

[0030] Figure 1C is according to Figure 1A a modified example of an enlarged sectional view of a part of the lid assembly.

[0031] Figure 2A is an illustration of when assembling according to Figures 1A - 1C a partial sectional view of the direction of the pressure applied to the lid assembly.

[0032] Figure 2B is a detailed illustration of according to Figure 2A a partial sectional view of the pressure distribution.

[0033] Figure 3 is an illustration of when assembling according toFigures 1A - 1C Computed tomography (CT) images of the deformed state of the rear cover component of the cover component.

[0034] Figure 4 Illustrates for each position of the gasket of the cover component according to Figures 1A - 1C A partial sectional view of the compression area.

[0035] Figure 5 Is used to compare the gasket according to Figures 1A - 4 And a partial perspective view of the gasket according to an embodiment of the present disclosure.

[0036] Figure 6 And Figure 7 Is a partial perspective view illustrating the detailed structure of the gasket according to an embodiment of the present disclosure.

[0037] Figure 8 Is a CT image illustrating the state after assembling the cover component to which the gasket according to an embodiment of the present disclosure is applied.

[0038] Figure 9 Is a longitudinal sectional view illustrating an exemplary cylindrical secondary battery. Detailed Description of the Invention

[0039] Embodiments of the present disclosure are provided to more fully describe the present disclosure to those skilled in the art. The following embodiments can be modified into many different forms, and the scope of the present disclosure is not limited to the following embodiments. On the contrary, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the spirit of the present disclosure to those skilled in the art.

[0040] In addition, in the following drawings, for convenience and clarity of illustration, the thickness or size of each layer may be enlarged, and the same reference numerals indicate the same elements in the drawings. As used in this specification, the term "and / or" may include any and all combinations of one or more of the related listed items. Further, in this specification, it should be understood that when component A is referred to as being "connected to" component B, component A may be directly connected to component B, or component C may be interposed between component A and component B such that component A is indirectly connected to component B.

[0041] The terms used herein are for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used in this specification, the singular form may include the plural form unless the context clearly indicates otherwise. Further, when used in this specification, the terms "comprises" and / or "comprising" specify the presence of the stated features, quantities, steps, operations, components, elements, and / or groups thereof, but do not preclude the presence or addition of one or more other features, quantities, steps, operations, components, elements, and / or groups thereof.

[0042] In this specification, although terms such as "first" and "second" may be used to describe various components, parts, regions, layers, and / or portions, these components, parts, regions, layers, and / or portions are not limited by these terms. These terms are used to distinguish one component, part, region, layer, or portion from another component, part, region, layer, or portion. Thus, without departing from the teachings of the present disclosure, the first component, part, region, layer, or portion described below may also refer to the second component, part, region, layer, or portion.

[0043] To facilitate understanding of the relationship between one element or feature and another element or feature as shown in the accompanying drawings, spatial relative terms such as "beneath", "below", "lower", "above", "upper" may be used herein. These spatial relative terms are intended to facilitate understanding of the present disclosure in accordance with various process states or usage states of the present disclosure and are not intended to limit the present disclosure. For example, when an element or feature in the drawings is flipped, an element or feature described as "beneath" or "below" may be changed to "above" or "upper". Thus, the term "beneath" may include the terms "above" and "below".

[0044] Hereinafter, a general cylindrical secondary battery will be briefly described with reference to the accompanying drawings.

[0045] Figure 1A is a longitudinal sectional view illustrating a general cylindrical secondary battery. Figure 1B is according to Figure 1A an enlarged sectional view of a part of the lid assembly. Figure 1C is according to Figure 1A an enlarged sectional view of a part of the lid assembly of a modified example.

[0046] See Figure 1A , a cylindrical secondary battery 1 as a general secondary battery includes: a cylindrical can 10 having one end open in the longitudinal direction, an electrode assembly 30 accommodated in the can 10, and a lid assembly 50 configured to seal the can 10.

[0047] The can 10 includes a circular bottom 12 and a side portion 14 extending upward from the bottom 12, and the upper part (or end portion) of the side portion 14 is open. In the process of manufacturing the secondary battery 1, the electrode assembly 30 is accommodated in the can 10 together with an electrolyte through the opening of the can 10. The can 10 may be formed of steel, steel alloy, nickel-plated steel, nickel-plated steel alloy, aluminum, aluminum alloy, or the like.

[0048] The crimping portion 16 and the caulking portion 18 are formed on the upper part of the side portion 14 to fix the lid assembly 50. The crimping portion 16 is formed by bending the side portion 14 concavely toward the inside of the can 10. The crimping portion 16 is the portion on which the lid assembly 50 is placed when assembling the lid assembly 50. The caulking portion 18 is formed by bending the end portion of the side portion 14 toward the inside of the can 10 after placing the lid assembly 50. The caulking portion 18 prevents the lid assembly 50 from separating from the can 10. The crimping portion 16 is formed to be spaced apart from the electrode assembly 30 so as not to contact the electrode assembly 30.

[0049] The electrode assembly 30 includes a negative electrode plate 31 coated with a negative electrode active material (e.g., graphite or carbon, etc.), a positive electrode plate 32 coated with a positive electrode active material (e.g., a transition metal oxide such as LiCoO2, LiNiO2 or LiMn2O4, etc.), and a separator 33 interposed between the negative electrode plate 31 and the positive electrode plate 32 to prevent a short circuit between the negative electrode plate 31 and the positive electrode plate 32. The negative electrode plate 31 may be a copper (Cu) foil or a nickel (Ni) foil, the positive electrode plate 32 may be an aluminum (Al) foil, and the separator 33 may include polyethylene (PE) or polypropylene (PP). A negative electrode tab 34 protruding downward by a certain length is welded to the negative electrode plate 31, and a positive electrode tab 35 protruding upward by a certain length is welded to the positive electrode plate 32. The negative electrode tab 34 is welded to the bottom 12 of the can 10, and the positive electrode tab 35 is welded to the lid assembly 50. Accordingly, the can 10 serves as a negative electrode, and the lid assembly 50 serves as a positive electrode. The negative electrode plate 31, the positive electrode plate 32 and the separator 33 are wound in a cylindrical shape and accommodated inside the can 10.

[0050] See Figure 1A and Figure 1B The lid assembly 50 includes a current interruption device (CID) 51, an upper lid 52 provided above the CID 51, and a lower lid 53 provided below the CID 51. The lid assembly 50 further includes an insulating member 54 inserted between the CID 51 and the lower lid 53 and configured to be insulated to prevent a portion other than the central portion of the CID 51 from contacting the lower lid 53, and an insulating gasket 55 configured to be insulated between the lid assembly 50 and the can 10. The gasket 55 may be provided between the side portion 14 and the CID 51. The upper portion of the gasket 55 may be provided between the caulking portion 18 and the CID 51, and the lower portion of the gasket 55 may be provided between the CID 51 and the crimping portion 16. The CID 51 may be provided in the open end portion of the side portion 14. The portion of the CID 51 at the center of the can 10 contacts the lower lid 53, and the portion of the CID 51 supported by the insulating member 54 is spaced apart from the lower lid 53. In the CID 51, an exhaust port (e.g., a notch) 51a is formed to rupture and discharge gas when the internal pressure rises above a certain pressure.

[0051] Meanwhile, the cover assembly may have a structure that includes only the CID 51 without an upper cover. As Figure 1C shown, the cover assembly may have a structure excluding the upper cover from the Figure 1A and Figure 1B shown cover assemblies. In this case, the edge of the CID 51 may be folded upward once, and the folded portion may be in close contact with the upper surface of the CID 51. The insulating layer 51b may be further provided between the upper surface of the CID 51 and the folded portion, on the upper surface of the folded portion, and between the CID 51 and the insulating member 54.

[0052] Figure 2A is a partial cross-sectional view illustrating the direction of the pressure applied when assembling the cover assembly according to Figures 1A - 1C . Figure 2B is a partial cross-sectional view illustrating in detail the pressure distribution according to Figure 2A . Figure 3 is a computed tomography (CT) image illustrating the deformed state of the cover assembly after assembling the cover assembly according to Figures 1A - 1B . Figure 4 is a partial cross-sectional view illustrating the compressed regions at each position of the gasket for the cover assembly according to Figures 1A - 1C .

[0053] Meanwhile, as Figure 2A shown, when the side portion 14 of the can 10 is pressed using a side jig to form the crimped portion 16, the pressure is applied to the gasket 55 from the crimped portion 16 in the order of arrows ①, ②, and ③. In addition, when the upper end of the side portion 14 is pressed using an upper jig to form the crimped joint 18, the pressure is applied to the gasket 55 from the crimped joint 18 in the order of arrows ①, ②, and ③.

[0054] At this time, Figure 2B region A is the region that generates a load by the pressure applied from above, and region B is the region that generates stress by the pressure applied from below. Therefore, the gasket 55 is compressed due to the pressure applied in the vertical direction. In addition, the pressure transmitted to the gasket 55 not only compresses the gasket 55 but also is transmitted to the lower cover 53 through the CID 51, the upper cover 52, and the insulating member 54 in the direction of the arrow in Figure 2B . This transmitted force causes the CID 51 and the upper cover 52 to deform in the downward direction.

[0055] See Figure 3 , in the CT image of the cover assembly 50, it can be seen that due to the deformation of the upper cover 52, the CID 51 also receives a load and deforms in the downward direction (for convenience, in Figure 3 , a secondary battery having a structure without an upper cover is illustrated, but it should be noted that the deformation of the CID is equally applicable to a secondary battery having an upper cover).

[0056] SeeFigure 4 When the region E, which is the upper region of the gasket 55, is compressed by 7% compared to its pre-deformed state, the region F, which is the lower region of the gasket 55, is compressed by 54% compared to its pre-deformed state. That is to say, the region F as the lower region can receive a relatively large amount of pressure.

[0057] When the lid assembly 50 is deformed as described above, the stability and reliability of the secondary battery 1 may deteriorate. Therefore, in order to solve this problem, in the present embodiment, a new structure gasket 500 that can reduce the deformation of the CID 51 is proposed (in the following description, for convenience, the detailed description of the configuration identical to that in Figures 1A - 4 will be omitted).

[0058] Figure 5 is a partial perspective view for comparing the gasket according to Figures 1A - 4 and the gasket according to an embodiment of the present disclosure. Figure 6 and Figure 7 are partial perspective views illustrating the detailed structure of the gasket according to an embodiment of the present disclosure (the remaining components other than the gasket are marked with (' or ”) in the reference numerals to distinguish them from the components in Figures 1A - 4 ).

[0059] See Figures 1A - 4 and Figure 5 The above-described gasket 55 has a substantially annular shape to surround and support the edges of the CID 51 and the upper lid 52. The gasket 55 has an outer peripheral surface 55a and an inner peripheral surface 55b, and the upper surface of the inner peripheral surface 55b is partially chamfered to have a short inclined surface 55c. On the other hand, the gasket 500 according to an embodiment of the present disclosure has a chamfered shape to have an upper inclined surface 516 that is longer than the short inclined surface 55c formed on the inner peripheral surface 55b of the gasket 55. In addition, the gasket 500 has a structure in which the lower region where the CID 51 is disposed bulges upward at a certain angle.

[0060] See Figure 5 The gasket 500 according to the present embodiment has a substantially annular shape and includes a main body 510 having a predetermined length in the vertical direction, a connecting portion 530 that is substantially vertically bent from the main body 510, and an extending portion 550 that extends substantially vertically downward from the connecting portion 530. The expression “substantially vertical” means that the angles between the main body 510 and the connecting portion 530 and between the connecting portion 530 and the extending portion 550 are vertical or nearly vertical, but the present disclosure is not limited to such angles. A protrusion 536 where the CID 51’ (see Figure 8 ) is disposed is formed at the upper part between the connecting portion 530 and the extending portion 550. In one embodiment, the gasket 500 may include a protrusion 536 configured to support the lower part of the CID 51’.

[0061] The main body 510 may include an outer peripheral surface 512 that is flat in the vertical direction, an inner peripheral surface 514, an upper inclined surface 516 inside the outer peripheral surface 512, and an upper surface 518 that connects the outer peripheral surface 512 to the upper inclined surface 516. The outer peripheral surface 512 is the surface that contacts the side portion 14 of the can 10, similar to Figures 1A - 4 the outer peripheral surface 55a of the gasket 55 shown in. The inner peripheral surface 514 is the portion that closely contacts the edge of the CID (see Figure 8 51' in). The inner peripheral surface 514 refers to the lower part of the outer peripheral surface 512 that is substantially bisected in the vertical direction. When the gasket 500 is bent, only a part of the upper side of the inner peripheral surface 514 bends and contacts the upper part of the CID 51'. The upper inclined surface 516 refers to the upper part of the outer peripheral surface 512 that is substantially bisected in the vertical direction. The upper inclined surface 516 is a surface formed by chamfering a part that was previously the inner peripheral surface into an inclined shape. The upper inclined surface 516 has a shape in which the distance from the outer peripheral surface 512 (e.g., the thickness of the main body) decreases toward the upper side. That is, the thickness of the upper part of the gasket 500 in the direction away from the electrode assembly 30 is smaller than the thickness of the lower part (e.g., the part where the connecting portion and the extending portion are located) of the gasket 500. In addition, the gasket 500 has an upper thickness that decreases toward the upper end of the gasket 500, and has a shape in which the thickness of the annular main body 510 decreases toward the end portion of the gasket 500.

[0062] The connecting portion 530 is a part of the gasket 500 that bends substantially perpendicularly from the main body 510 so as to have a predetermined length in the horizontal direction. The connecting portion 530 has an outer surface 532 and an inner surface 534, and the distance between the outer surface 532 and the inner surface 534 (e.g., the thickness of the connecting portion 530) may be equal to or similar to the distance between the outer peripheral surface 512 and the inner peripheral surface 514 of the main body 510. A part of the inner surface 534 bulges upward to form a protrusion 536.

[0063] In the protrusion 536, a part of the inner surface 534 bulges and slopes upward to form a highest point (e.g., top dead center). The surface formed to slope downward from the highest point is connected to the extending portion 550. The surface that bulges upward to form the highest point is defined as the first inclined surface 536a, and the surface that extends downward from the first inclined surface 536a is defined as the second inclined surface 536b. Figure 5It is illustrated that the first inclined surface 536a and the second inclined surface 536b are connected to form a projection 536 with a triangular cross-section. The angle between the first inclined surface 536a and the outer surface (or lower surface) 532 of the connecting portion 530 may be in the range of 7° to 14°. The highest point of the projection 536 is the part that receives the maximum force caused by stress. By increasing the thickness of the part where the stress is applied and making the part that sags under stress protrude in the direction opposite to the sagging direction, the force applied to the CID 51' can be reduced. Therefore, the force applied to the upper cover can also be reduced.

[0064] The starting point of the first inclined surface 536a described above is the lowest point in the projection 536. When the height from the outer surface 532 to the highest point is 0.7 mm, the height difference between the lowest point and the highest point may be 0.2 mm. That is, the height from the outer surface 532 to the lowest point is 0.5 mm (in Figure 5 it, the horizontal line extending the outer surface is defined as L1, the line parallel to L1 passing through the lowest point is defined as L2, and the line parallel to L1 passing through the highest point is defined as L3. L1 and L2 are similarly applicable to Figure 6 and Figure 7 ).

[0065] For convenience, the inner surface 534 and the projection 536 are described with separate reference numerals. However, since the projection 536 is formed by changing the shape of the inner surface 534, the projection 536 may be referred to as the inner surface or the projection.

[0066] The extension portion 550 is a portion that is bent substantially vertically at the end portion of the connecting portion 530 and extends downward to have a predetermined length. The extension portion 550 has an outer peripheral surface 552, an inner peripheral surface 554, and a lower surface 558 connecting the outer peripheral surface 552 and the inner peripheral surface 554. The above-mentioned projection 536 is connected to the upper part of the inner peripheral surface 554.

[0067] The main body 510, the connecting portion 530, and the extension portion 550 have been described separately above, but this is only for clearly illustrating the structure. The main body 510, the connecting portion 530, and the extension portion 550 may be integrally formed, and the gasket 500 has an integrally connected annular shape.

[0068] In the above embodiment, the projection 536 is illustrated as having a triangular cross-section. However, the cross-sectional shape of the projection 536 may be any one of a streamline shape, a semi-circular shape, a semi-elliptical shape, and a polygonal shape.

[0069] In Figure 6In the embodiment shown, the cross-sectional shape of the protrusion 536' is a streamlined shape. When the height from the outer surface 532' to the lowest point of the protrusion 536' is 0.5 mm, the angle between the line L2 passing through the lowest point of the protrusion 536' and the first inclined surface 536a' can be 7°. Similarly, since L1 and L2 are parallel to each other, the angle between the first inclined surface 536a' and L1 is also 7°.

[0070] In Figure 7 the embodiment shown, the cross-sectional shape of the protrusion 536” is also a streamlined shape. When the height from the outer surface 532” to the lowest point of the protrusion 536” is 0.5 mm, the angle between the line L2 passing through the lowest point of the protrusion 536” and the first inclined surface 536a” can be 14°. Similarly, since L1 and L2 are parallel to each other, the angle between the first inclined surface 536a” and L1 is also 14°.

[0071] The above Figures 5 - 7 highest points of the protrusions 536, 536' and 536” should be located in the recessed deformation section of the gasket 500 after maximizing compression by crimping.

[0072] Figure 8 is a CT image illustrating the state after assembling the gasket to which the embodiment according to the present disclosure is applied to the lid assembly.

[0073] In Figure 8 , the gasket 500 is maximally compressed by crimping and is supported by the crimping portion 16'. At this time, the section shown by the solid line is the section where the gasket 500 is supported and is the stress generation section. That is, the section shown by the solid line is the section where the gasket 500 is deformed due to stress. The section shown by the dashed line is the section where the gasket 500 is not supported. This section is the section where the CID 51' is recessed and deformed due to the sag of the gasket rather than due to stress. This section is conveniently referred to as the recessed deformation section, which can be a preset point of the CID 51'. That is, when applying the gaskets 500, 500' and 500” described above, the upwardly protruding sections of the protrusions 536, 536' and 536” are located in the recessed deformation section (the highest point of the protrusion is closer to the center of the can in the diameter direction of the can than the end portion of the crimping portion). In one embodiment, the highest point of the protrusion can contact the preset point of the CID 51'. Therefore, the deformation of the CID can be minimized. Figures 5 - 7 Referring to

[0074] Referring to Figure 8 , it can be seen that in the CT image of the actual lid assembly to which the gasket 500 of the present embodiment is applied, the CID51' is not deformed in the downward direction.

[0075] As described above, according to an embodiment of the present disclosure, by improving the shape of the gasket, when a caulking portion and a crimping portion are formed on the can for assembling the lid assembly, components such as the upper lid and the safety vent will not be deformed due to pressure. Therefore, the stability of the secondary battery can be improved.

[0076] Meanwhile, the above-described structure of the gasket can also be applied to other types of cylindrical secondary batteries.

[0077] Figure 9 is a longitudinal sectional view of an exemplary cylindrical secondary battery.

[0078] The exemplary secondary battery 910 may include a can 100, an electrode assembly 200, a first current collector plate 300, a second current collector plate 400, a negative electrode lead 450, an insulating member 590, a positive electrode terminal 600, a first gasket 700, a cover plate 800, and a second gasket 900.

[0079] The can 100 houses the electrode assembly 200 and the electrolyte, and may have a generally cylindrical shape. The can 100 includes a circular upper surface portion 110 and a side portion 120 extending downward from the upper surface portion 110. The positive electrode terminal 600 and the first gasket 700 may be coupled to the upper surface portion 110. A crimping portion 122 and a caulking portion 124 may be formed on the lower portion of the side portion 120. When the electrode assembly 200 is assembled in the can 100, the crimping portion 122 is formed by setting the can 100 with the upper surface portion 110 facing downward after inserting the electrode assembly 200. The electrode assembly 200 can be prevented from separating from the can 100 by the crimping portion 122. The crimping portion 122 may be formed by processing the lower end of the side portion 120 to be concave toward the inside of the can 100. After the crimping portion 122 is formed, the cover plate 800 and the second gasket 900 are assembled, and the caulking portion 124 is formed to prevent the cover plate 800 from separating from the can 100. The caulking portion 124 may be formed by bending the end portion of the side portion 120 toward the inside of the can 100.

[0080] The electrode assembly 200 may be arranged such that the uncoated portion of the first electrode plate 210 protrudes upward farther than the upper end of the second electrode plate 220. In addition, the uncoated portion of the second electrode plate 220 is arranged to protrude downward farther than the lower end of the first electrode plate 210, and the electrode assembly 200 may be wound in a jelly-roll shape. In this state, the first current collector plate 300 may be welded to the uncoated portion of the first electrode plate 210, and the second current collector plate 400 may be welded to the uncoated portion of the second electrode plate 220.

[0081] The first current collector plate 300 is welded and electrically connected to the first electrode plate 210 serving as a positive electrode plate, so the first current collector plate 300 can be defined as a positive electrode current collector plate. The first current collector plate 300 may have a substantially disk shape. The first current collector plate 300 may be electrically connected to the positive electrode terminal 600 at its central portion. A plate-shaped insulating member 590 may be provided between the first current collector plate 300 and the can 100.

[0082] The second current collector plate 400 is welded and electrically connected to the second electrode plate 220 serving as a negative electrode plate, so the second current collector plate 400 can be defined as a negative electrode current collector plate. The second current collector plate 400 may have a substantially disk shape. The second current collector plate 400 may be electrically connected to the side portion 120 of the can 100 through a plurality of negative electrode leads 450. Since the negative electrode leads 450 are electrically connected to the side portion 120, the can 100 becomes a negative electrode. Therefore, the positive electrode terminal 600 is installed to be insulated from the can 100.

[0083] The positive electrode terminal 600 is installed to be insulated from the upper surface portion 110 of the can 100 through the first gasket 700. Exemplarily, the positive electrode terminal 600 may be a rivet terminal riveted to the upper surface portion 110 from the inside or outside of the can 100.

[0084] The first gasket 700 insulates the positive electrode terminal 600 from the can 100. Exemplarily, the first gasket 700 may include an upper gasket 710 that insulates the positive electrode terminal 600 from the outer surface of the upper surface portion 110 and a lower gasket 720 that insulates the positive electrode terminal 600 from the inner surface of the upper surface portion 110.

[0085] The cover plate 800 may be a substantially disk-shaped plate and may be coupled to the side portion 120 through the second gasket 900. The cover plate 800 may be fixed to the can 100 through a crimping portion 122 and a caulking portion 124. Since the second gasket 900 is provided between the cover plate 800 and the side portion 120, the cover plate 800 is insulated from the can 100. Therefore, the cover plate 800 becomes neutral (i.e., non-polar), having neither a negative polarity nor a positive polarity. A notch 810 for discharging gas may be provided in the plate surface of the cover plate 800.

[0086] See above Figures 5 - 7 The shapes of the gaskets 500, 510' and 510'' described above can be applied to the second gasket 900. That is, Figure 9 the second gasket 900 of Figures 5 - 7 can be replaced with one of the gaskets 500, 510' and 510''.

[0087] Therefore, when the crimping portion and the caulking portion are formed on the can for assembling the cover plate, the cover plate and the notch are not deformed due to the pressure. Therefore, the stability of the secondary battery can be improved.

[0088] According to an embodiment of the present disclosure, by improving the shape of the gasket, when a caulking portion and a curling portion are formed on a can for assembling a lid assembly, components such as an upper lid and a safety vent do not deform due to pressure. Therefore, the stability of the secondary battery can be improved.

[0089] Hereinafter, a method of manufacturing a secondary battery according to an embodiment of the present disclosure will be described.

[0090] The method of manufacturing a secondary battery may include: forming a cylindrical can including a circular bottom, a side portion extending from the circular bottom, a curling portion, and a caulking portion, wherein the curling portion is recessed at one end of the side portion and the caulking portion is formed by bending an end portion of the side portion; accommodating an electrode assembly in the cylindrical can; accommodating a current interruption device in the cylindrical can; and sealing the cylindrical can with a lid assembly including a gasket insulated from the cylindrical can, wherein the gasket includes an annular body, a connecting portion extending from the annular body, an extending portion extending downward from the connecting portion, and a protrusion protruding upward from the connecting portion, and the method further includes supporting a lower portion of the current interruption device with the protrusion.

[0091] The method may further include forming the gasket into a shape in which the thickness of the annular body decreases toward an end portion of the gasket.

[0092] Forming the gasket may include: bending the connecting portion of the gasket at a predetermined angle to extend from the annular body, and forming a protrusion protruding from an upper surface of the connecting portion.

[0093] The method may further include: positioning an upper portion of the gasket between the caulking portion and the current interruption device, and positioning a lower portion of the gasket between the current interruption device and the curling portion.

[0093] The above description is only for implementing an embodiment of the present disclosure, and the present disclosure is not limited to the above embodiment. As claimed in the claims, the technical spirit of the present disclosure includes the scope in which those skilled in the art can make various changes without departing from the gist of the present disclosure.

Claims

1. A secondary battery, comprising: A cylindrical can, including a circular bottom and a side portion extending from the circular bottom, the side portion having an open end portion; An electrode assembly accommodated in the cylindrical can; A current interruption device provided in the open end portion of the side portion and having an exhaust port in the current interruption device; And A gasket provided between the side portion and the current interruption device and including a protrusion configured to support a lower portion of the current interruption device.

2. The secondary battery according to claim 1, wherein the gasket includes an insulating material.

3. The secondary battery according to claim 1 or 2, wherein a cross-sectional shape of the protrusion is any one of a triangular shape, a streamline shape, a semi-circular shape, a semi-elliptical shape, and a polygonal shape.

4. The secondary battery according to claim 3, wherein a highest point of the protrusion contacts a preset point of the current interruption device.

5. The secondary battery according to claim 4, wherein the side portion includes a crimped portion adjacent to one end of the side portion and having an inward concave shape and a crimping portion including an inwardly curved end portion of the side portion.

6. The secondary battery according to claim 5, wherein: An upper portion of the gasket is provided between the crimping portion and the current interruption device, and A lower portion of the gasket is provided between the current interruption device and the crimped portion, and the protrusion protrudes from an upper surface of the lower portion of the gasket.

7. The secondary battery according to claim 6, wherein the highest point of the protrusion is set to be closer to a center of the cylindrical can than an end portion of the crimping portion in a diameter direction of the cylindrical can.

8. The secondary battery according to claim 6, wherein, When the cross-section of the protrusion has a triangular shape or a streamline shape, an angle of an upwardly protruding inclined surface of the protrusion with respect to a lower surface of the lower portion of the gasket is in a range of 7° to 14°.

9. A secondary battery, comprising: A cylindrical can, including a circular bottom, a side portion extending from the circular bottom, a crimped portion having a concave shape at one end of the side portion, and a crimping portion including a curved end portion of the side portion; An electrode assembly accommodated in the cylindrical can; A lid assembly configured to seal the cylindrical can and including a gasket configured to be insulated from the cylindrical can; And A current interruption device, Wherein the gasket includes an annular main body, a connecting portion extending from the annular main body, an extending portion extending downward from the connecting portion, and a protrusion protruding upward from the connecting portion to support a lower portion of the current interruption device.

10. The secondary battery according to claim 9, wherein the gasket includes an insulating material.

11. The secondary battery according to claim 9 or 10, wherein a cross-sectional shape of the protrusion is any one of a triangular shape, a streamline shape, a semi-circular shape, a semi-elliptical shape, and a polygonal shape.

12. The secondary battery according to claim 11, wherein the gasket has a shape in which a thickness of the annular main body decreases toward an end portion of the gasket.

13. The secondary battery according to claim 12, wherein: The connecting portion of the gasket is curved and extends from the annular body at a predetermined angle, and the protrusion protrudes from the upper surface of the connecting portion.

14. The secondary battery according to claim 13, wherein: the annular body of the gasket is disposed between the crimping portion and the current interruption device, and the connecting portion of the gasket is disposed between the current interruption device and the crimping portion.

15. The secondary battery according to claim 14, wherein the highest point of the protrusion is set to be closer to the center of the cylindrical can than the end portion of the crimping portion in the diameter direction of the cylindrical can.

16. The secondary battery according to claim 15, wherein the protrusion includes a first inclined surface protruding upward and a second inclined surface extending downward and inclined from the first inclined surface, and when the protrusion has a triangular cross-section or a streamline cross-section, the angle between the first inclined surface and the lower surface of the connecting portion is in the range of 7° to 14°.

17. A method of manufacturing a secondary battery, the method comprising: forming a cylindrical can including a circular bottom, a side portion extending from the circular bottom, a crimping portion, and a crimping portion, wherein the crimping portion is recessed at one end of the side portion and the crimping portion is formed by bending the end portion of the side portion; accommodating an electrode assembly in the cylindrical can; accommodating a current interruption device in the cylindrical can; and sealing the cylindrical can with a cover assembly including a gasket insulated from the cylindrical can, wherein the gasket includes an annular body, a connecting portion extending from the annular body, an extending portion extending downward from the connecting portion, and a protrusion protruding upward from the connecting portion, and the method further includes supporting a lower portion of the current interruption device with the protrusion.

18. The method according to claim 17, further comprising forming the gasket into a shape in which the thickness of the annular body decreases toward the end portion of the gasket.

19. The method according to claim 18, wherein forming the gasket includes: bending the connecting portion of the gasket at a predetermined angle to extend from the annular body, and forming the protrusion to protrude from the upper surface of the connecting portion.

20. The method according to claim 19, further comprising: positioning an upper portion of the gasket between the crimping portion and the current interruption device, and positioning a lower portion of the gasket between the current interruption device and the crimping portion.

Images