Cylindrical secondary battery

Abstract

An embodiment of the present invention relates to a cylindrical secondary battery, which may include: an electrode assembly; a cylindrical can in which the electrode assembly is accommodated; and a cap assembly coupled to the can, electrically connected to the electrode assembly, insulated from the can, and a cover that covers the can and includes an upper cover that is exposed to the outside, a lower cover that supports the upper cover, an exhaust plate that is disposed between the upper cover and the lower cover to be spaced apart from the lower cover and has at least one notch formed therein, and an insulator that is made of an insulating material and is disposed between the upper cover and the lower cover and the can, the upper cover includes a plurality of perforations formed through the plate surface, a plurality of bridges disposed between the perforations, and a plurality of discharge holes formed through the plate surface and spaced apart from the perforations. According to the embodiment of the present invention, the discharge direction of the internal gas in the secondary battery is not bent and the gas can be discharged in a linear direction, so that the internal gas can be rapidly discharged.

Description

Technical Field

[0001] Embodiments of the present invention relate to a cylindrical secondary battery with a cover assembly having an improved structure. Background Technology

[0002] Typically, a cylindrical secondary battery includes: a cylindrical electrode assembly; a cylindrical can containing the electrode assembly and electrolyte; and a cap assembly that is attached to the upper opening of the can to seal the can and allow current generated in the electrode assembly to flow to an external device.

[0003] The cover assembly can consist of an upper cover, a vent plate, and a lower cover, with an insulator for insulation disposed between the vent plate and the lower cover. A notch is formed in the vent plate, and the notch breaks due to the increased internal pressure of the secondary battery when gas is generated. Gas discharged through the notch escapes to the outside of the secondary battery through a perforation formed in the upper cover. However, because the internal gas can only be discharged through the perforation, it may be difficult to discharge the gas quickly, which is problematic. Therefore, when venting the internal gas of the secondary battery, a path for rapid discharge needs to be ensured.

[0004] The information disclosed in this background section is only intended to enhance the understanding of the background of the present invention, and therefore may contain information that does not constitute prior art. Summary of the Invention

[0005] Technical issues Embodiments of the present invention provide a cylindrical secondary battery having a cover assembly capable of rapidly venting internal gases.

[0006] Technical solution A cylindrical secondary battery according to an embodiment of the present invention may include: an electrode assembly; a cylindrical can in which the electrode assembly is housed; and a cover assembly coupled to the can, electrically connected to the electrode assembly, insulated from the can, and including an upper cover exposed to the outside, a lower cover supporting the upper cover, a vent plate disposed between the upper cover and the lower cover and spaced apart from the lower cover and having at least one notch therein, and an insulator made of an insulating material and disposed between the lower cover and the vent plate, wherein the upper cover includes a plurality of perforations formed through the plate surface, a plurality of bridges disposed between the perforations, and a plurality of vent holes formed through the plate surface and spaced apart from the perforations.

[0007] The top cover has a lower part that contacts the exhaust plate, an upper part that protrudes upward from the lower part, and a perforation is formed at the boundary between the lower and upper parts.

[0008] The drain hole can be formed in the upper part of the cover.

[0009] The drain hole can be formed along the upper edge of the cover.

[0010] The discharge hole can be one of the following shapes: round, oval, rectangular, or arc-shaped.

[0011] Drainage holes can be located between the two ends of each perforation.

[0012] The discharge hole can be formed on the outside of the minimum weld diameter area, where the top cover is welded to the manifold.

[0013] The discharge hole can be configured such that at least a portion of the discharge hole corresponds to the position of the notch.

[0014] The discharge hole can be stacked with the notch.

[0015] Additionally, the cylindrical secondary battery according to an embodiment of the present invention may include an electrode assembly, a cylindrical can containing the electrode assembly therein, and a cover assembly, the cover assembly being electrically connected to the electrode assembly, insulated from the can, and including: an upper cover exposed to the outside and having a plurality of perforations formed therethrough; a lower cover supporting the upper cover; a vent plate disposed between the upper cover and the lower cover, spaced apart from the lower cover, and having at least one notch formed therein; and an insulator made of insulating material and disposed between the lower cover and the vent plate, wherein the upper cover has a double-hole structure having a plurality of vent holes spaced apart from and formed therethrough from the perforations.

[0016] The top cover may have a lower circular plate-shaped portion that contacts the exhaust plate, an upper circular plate-shaped portion that protrudes upward from the lower portion, and perforations formed at the boundary between the lower and upper portions.

[0017] The drain hole can be formed along the upper edge of the cover.

[0018] The discharge hole can be one of the following shapes: round, oval, rectangular, or arc-shaped.

[0019] Drainage holes can be located between the two ends of each perforation.

[0020] The discharge hole can be formed on the outside of the minimum weld diameter area, where the top cover is welded to the manifold.

[0021] The discharge hole can be configured such that at least a portion of the discharge hole corresponds to the position of the notch.

[0022] The discharge hole can be stacked with the notch.

[0023] Beneficial effects According to the disclosed embodiments, the gas inside the secondary battery can be discharged in a straight line without bending, thereby quickly discharging the internal gas. Attached Figure Description

[0024] Figure 1This is a perspective view showing a cylindrical secondary battery according to an embodiment of the present invention.

[0025] Figure 2 is based on Figure 1 A cross-sectional view of a cylindrical secondary battery.

[0026] Figure 3 This is a plan view showing the top cover according to an embodiment of the present invention.

[0027] Figure 4 It shows the internal gas passing through according to Figure 3 A side sectional view of the path through which the top cover discharges.

[0028] Figure 5 This is a plan view showing the top cover according to another embodiment of the present invention.

[0029] Figure 6 This is an exemplary plan view showing the diameter of the top cover and the diameter of the discharge hole according to an embodiment of the present invention.

[0030] Figure 7 This is an exemplary plan view showing the location of the discharge hole of the top cover according to an embodiment of the present invention. Detailed Implementation

[0031] Preferred embodiments of the invention will be described in detail below with reference to the accompanying drawings. Examples of the invention are provided to explain it more fully to those skilled in the art, and the following examples can be modified in various other forms. However, the invention can be embodied in many different forms and should not be construed as limited to the exemplary (or exemplary) embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete, and will convey aspects and features of the invention to those skilled in the art.

[0032] Additionally, for the sake of brevity and clarity, the dimensions or thicknesses of various components are exaggerated in the accompanying drawings. The same reference numerals consistently denote the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Furthermore, it will be understood that when element A is referred to as being "connected to" element B, element A may be directly connected to element B, or an intermediary element C may exist between them such that element A and element B are indirectly connected to each other.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that when the terms “comprising or including” and / or variations thereof are used in this specification, it indicates the presence of the stated features, quantities, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, quantities, steps, operations, elements, components, and / or groups thereof.

[0034] It will be understood that although the terms first, second, etc., may be used herein to describe various components, elements, regions, layers, and / or portions, these components, elements, regions, layers, and / or portions should not be limited by these terms. These terms are used only to distinguish one component, element, region, layer, and / or portion from another component, element, region, layer, and / or portion. Thus, for example, without departing from the teachings of the invention, the first component, first element, first region, first layer, and / or first portion discussed below may be referred to as a second component, second element, second region, second layer, and / or second portion.

[0035] For ease of description, spatial relative terms such as “below,” “under,” “lower,” “above,” and “upper” may be used herein to describe the relationship between one element or feature as shown in the figure and another element(s). It will be understood that, in addition to the orientation shown in the figure, the spatial relative terms are intended to cover different orientations of the device in use or operation. For example, if an element or feature in the figure is flipped, an element described as “below” or “under” other elements or features would be oriented “above” or “upper” other elements or features. Thus, the exemplary term “below” can cover both above and below orientations.

[0036] In the following, a cylindrical secondary battery according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0037] Figure 1 Figure 2 is a perspective view illustrating a cylindrical secondary battery according to an embodiment of the present invention. Figure 1 A cross-sectional view of a cylindrical secondary battery. Figure 3 This is a plan view showing the top cover according to an embodiment of the present invention.

[0038] like Figure 1As shown in Figure 2, the cylindrical secondary battery 10 according to the first embodiment of the present invention may include a cylindrical can 100, an electrode assembly 300 inserted into the interior of the can 100, a cap assembly 500 inserted into one end of the can 100, and an insulating washer 136 inserted between the can 100 and the cap assembly 500. The electrode assembly 300 may be supported by a central pin 380.

[0039] Can 100 includes a circular bottom 110 and a side portion 130 extending upward from the bottom 110, the upper part of which is open (hereinafter referred to as an opening). Can 100 may be formed of steel, steel alloy, nickel-plated steel, nickel-plated steel alloy, aluminum, aluminum alloy, or equivalents thereof, but is not limited thereto. A lid assembly 500 is inserted into the opening of can 100. A crimped portion 132 and a crimped portion 134 may be formed on the side portion 130 to prevent the inserted lid assembly 500 from separating to the outside through the opening of can 100.

[0040] The rolled edge portion 132 is formed at the lower part relative to the cover assembly 500 and is recessed towards the interior of the can 100. The crimping portion 134 is formed at the upper part relative to the cover assembly 500 and is curved towards the interior of the can 100. Because the rolled edge portion 132 and the crimping portion 134 hold the cover assembly 500 upward and downward, the cover assembly 500 does not separate from the can 100. In the manufacture of the secondary battery 10, the electrode assembly 300 can be inserted into the can 100 together with the electrolyte through the opening of the can 100.

[0041] Electrode assembly 300 includes a negative electrode plate 310, a positive electrode plate 320, and a separator 330. The negative electrode plate 310 may have a negative electrode active material (e.g., graphite, carbon, etc.) formed on both sides. The positive electrode plate 320 may have a positive electrode active material (e.g., transition metal oxides (LiCoO2, LiNiO2, LiMn2O4, etc.)) formed on both sides. The separator 330 is disposed between the negative electrode plate 310 and the positive electrode plate 320 to prevent short circuits and to allow only lithium ion movement. The negative electrode plate 310, the positive electrode plate 320, and the separator 330 are wound into a generally cylindrical shape and can be housed inside a can 100. The negative electrode plate 310 may be copper (Cu) foil or nickel (Ni) foil, the positive electrode plate 320 may be aluminum (Al) foil, and the separator 330 may be polyethylene (PE) or polypropylene (PP), but the present invention does not limit the materials to those listed above. A negative electrode tab 340 protruding downwards to extend a certain length from the negative electrode plate 310 can be welded in, and a positive electrode tab 350 protruding upwards to extend a certain length from the positive electrode plate 320 can be welded in, but the reverse is also possible. The negative electrode tab 340 can be made of copper or nickel, and the positive electrode tab 350 can be made of aluminum, but the invention does not limit the materials to those listed above. The negative electrode tab 340 can be welded to the bottom 110 of the can 100, in which case the can 100 can operate as a negative electrode. Conversely, the positive electrode tab 350 can be welded to the bottom 110 of the can 100, in which case the can 100 can operate as a positive electrode. In this embodiment, as an example, the negative electrode tab 340 is welded to the bottom 110 of the can 100.

[0042] Additionally, the first insulating plate 360 ​​and the second insulating plate 370 can be positioned between the upper and lower parts of the electrode assembly 300. The first insulating plate 360 ​​prevents the positive electrode plate 320 from making electrical contact with the bottom 110 of the canister 100, and the second insulating plate 370 prevents the negative electrode plate 310 from making electrical contact with the cover assembly 500.

[0043] In the first insulating plate 360, a first hole 362 communicating with the center pin 380 and a second hole 364 forming therethrough, allowing the negative electrode tab 340 to pass through, can be formed through the first insulating plate 360. When a large amount of gas is generated due to an anomaly in the secondary battery, the first hole 362 allows the gas to move upward through the cylindrical center pin 380. The negative electrode tab 340 can pass through the second hole 364 and is then soldered to the bottom 110.

[0044] In the second insulating plate 370, a first hole 372, allowing gas to move into the cover assembly 500 when a large amount of gas is generated due to an anomaly in the secondary battery, can be formed through the second insulating plate 370. Additionally, the second insulating plate 370 may have a second hole 374 formed therethrough, allowing the positive electrode tab 350 to pass through it. The positive electrode tab 350 can be welded to the lower cover 550, which will be described later, through the second hole 374. Multiple second holes 374 can be formed and can serve as inlets through which electrolyte is injected into the electrode assembly 300 during the electrolyte injection process.

[0045] Alternatively, although not shown in the accompanying drawings, other current collector structures can be applied to the secondary battery of this embodiment. That is, uncoated portions of the negative and positive electrodes are formed, in which active materials are not respectively coated onto the negative and positive electrode plates, and current collectors electrically connected to the uncoated portions of the negative and positive electrodes can be provided respectively. Here, the current collectors can be positioned at the location of the aforementioned insulating plate. In this case, the negative electrode current collector can be electrically connected to the can, and the positive electrode current collector can be electrically connected to the cover assembly while being insulated from the can.

[0046] The center pin 380 is in the shape of a hollow cylindrical tube and can be approximately attached to the center of the electrode assembly 300. The center pin 380 can be formed of steel, steel alloy, nickel-plated steel, nickel-plated steel alloy, aluminum, aluminum alloy, or polybutylene terephthalate, but the material is not limited to these. The center pin 380 suppresses deformation of the electrode assembly 300 during the charging and discharging of the secondary battery and serves as a channel for the movement of gas generated inside the secondary battery. In some cases, the center pin 380 can be omitted.

[0047] At the same time, such as Figure 1 As shown in Figure 2, the cover assembly 500 may include an upper cover 510 exposed to the outside of the can 100, a lower cover 550 located below the upper cover 510, a vent plate 530 located between the upper cover 510 and the lower cover 550, and an insulator 570 located between the vent plate 530 and the lower cover 550. In Figure 2, the direction toward the center pin 380 is defined as the inward direction, and the direction away from the center pin 380 is defined as the outward direction.

[0048] As shown in Figure 2 and Figure 3As shown, the upper cover 510 is located at the uppermost part of the cover assembly 500 and may include perforations 512 for venting gas generated inside the canister 100 to the outside. The upper cover 510 may have a generally circular shape, and a predetermined area may convexly project upward around a central axis A. One or more perforations 512 may be formed at the boundary between the circular portion and the protrusion. The remaining portion without perforations 512 may be defined as a bridge 514. Additionally, in the upwardly projecting portion, a plurality of vent holes 516 may be formed therethrough. The specific structure of the upper cover 510 will be described later. An exhaust plate 530 is disposed below the upper cover 510, and the exhaust plate 530 may be wrapped around the edge of the upper cover 510.

[0049] The vent plate 530 has a generally circular shape and an edge that curves toward the edge of the upper cover 510, thereby contacting the lower edge of the upper cover 510. The vent plate 530 may bend again toward the interior of the can 100 around the portion that contacts the upper cover 510, so as to contact the upper edge of the upper cover 510. In the vent plate 530, the uncurved circular portion is defined as the vent bottom 532, the portion curving toward the upper cover 510 from the vent bottom 532 is defined as the first support portion 534, and the portion curving inward from the first support portion 534 is defined as the second support portion 536. The portion that protrudes downward from the vent bottom 532 and contacts the lower cover 550 is defined as the contact portion 538. The vent plate 530 is formed such that all areas except the contact portion 538 do not contact the lower cover 550. At least one notch 532a may be formed on the vent bottom 532 of the vent plate 530. For example, the notch 532a may be formed such that at least a portion of it corresponds to the location of the discharge hole 516 of the upper cover 510, which will be described later. When the internal gas pressure of the canister 100 exceeds the predetermined rupture pressure, the notch 532a may rupture as the vent plate 530 flips upward. Therefore, the internal gas of the canister 100 can be quickly released to the outside through the vent hole 516 of the top cover 510.

[0050] The lower cover 550 is disposed below the exhaust plate 530 and has an approximately circular plate shape. For example, the lower cover 550 can be made of aluminum, aluminum alloy, or equivalents, but the material is not limited to these. The lower cover 550 supports the upper cover 510 to prevent the upper cover 510 from deforming due to external forces. The edge of the lower cover 550 is bent toward the exhaust plate 530, and an insulator 570 is placed at the bent portion. The portion bent toward the exhaust plate 530 is defined as a third support portion 552. In the lower cover 550, the unbent circular plate portion is defined as the lower cover bottom 554, and the lower cover bottom 554 can be formed to have a predetermined gap with the exhaust bottom 532 of the exhaust plate 530. However, the approximate center portion of the lower cover bottom 554 is in contact with the contact portion 538 of the exhaust plate 530. The lower cover 550 may also have a perforation 554a formed on the lower cover bottom 554. Therefore, the internal gas can be released to the outside of the tank 100 through the perforation 554a of the lower cover 550, the notch 532a of the exhaust plate 530, and the perforation 512 of the upper cover 510.

[0051] The insulator 570 allows the exhaust plate 530 and the lower cover 550 to remain spaced apart except for the contact portion 538, and serves to insulate the exhaust plate 530 and the lower cover 550 from each other. Therefore, when viewed from above, the insulator 570 can be formed into a ring shape with a certain width. For example, the insulator 570 can be formed from, but is not limited to, polyethylene (PE), polypropylene (PP), polystyrene (PS), ethylene-vinyl acetate copolymer (EVA), or equivalents thereof. The insulator 570 can be bonded to the exhaust plate 530 and the lower cover 550 by ultrasonic welding, laser welding, fusion welding, or other methods.

[0052] In a secondary battery without the above-described structure, gas is discharged through the perforation 512 when the notch 532a of the vent plate 530 ruptures during internal gas discharge. The gas discharge path through the perforation 512 penetrating the upper cover 510 at the upper part of the electrode assembly 300 has a curved path instead of a straight path (see...). Figure 4 (The curved arrow in the image). Therefore, due to the reduced efficiency of internal gas discharge, it is necessary to ensure a path for rapid discharge. To this end, the present invention proposes a cover structure equipped with a separate discharge port.

[0053] The construction of the cover according to various embodiments of the present invention will be described in detail below.

[0054] Figure 4 It shows the internal gas passing through according to Figure 3 A side sectional view of the path through which the top cover discharges. Figure 5 This is a plan view showing the top cover according to another embodiment of the present invention. Figure 6 This is an exemplary plan view showing the diameter of the top cover and the diameter of the discharge hole according to an embodiment of the present invention. Figure 7This is an exemplary plan view showing the location of the discharge hole of the top cover according to an embodiment of the present invention.

[0055] Refer again Figure 3 According to one embodiment of the present invention, the upper cover 510 may include a plurality of perforations 512, a bridge 514 formed between each perforation 512, and a plurality of discharge holes 516 formed through the uppermost surface of the upper cover 510. Based on an imaginary center point of the upper cover 510, the perforations 512 and the bridge 514 may be arc-shaped with the same center point.

[0056] The top cover 510 is circular in plan, and the upwardly protruding portion is also circular. For convenience, the edge region of the top cover 510, which is coupled to the exhaust plate 530, is referred to as the lower part, and the upwardly protruding portion is referred to as the upper part. Multiple exhaust holes 516 can pass through the upper part of the top cover 510 circumferentially. The multiple exhaust holes 516 can be arranged at equal intervals. For example, as... Figure 3 As shown, the discharge holes 516 can be circular and can be six in number. Although not shown in detail in the figure, the number of discharge holes 516 formed can range from a minimum of 2 to a maximum of 14; however, this is only an example, and the number of discharge holes 516 can vary depending on the diameter of the cover 510, the number of perforations 512, etc. For example, based on the imaginary center point of the cover 510, the discharge holes 516 can be positioned within an angular range between the two ends of each perforation 512. For example, as... Figure 6 As shown in B, the discharge port 516 can be located near either end of each perforation 512. Or, as... Figure 7 As shown in Figure C, the discharge hole 516 can be located at a position corresponding to the center of each through hole 512. The discharge hole 516 can be located near both ends of each bridge 514, but it can be located outside the position corresponding to the center of each bridge 514. Figure 7 (Position D in the middle). Bridge 514 is a blocking part in the upper cover 510, and therefore may slightly obstruct the exhaust of internal gas.

[0057] Additionally, the discharge hole 516 can be configured such that at least a portion of it corresponds to the position of the recess 532a formed in the exhaust plate 530. The degree of overlap between the recess 532a and the discharge hole 516 can vary depending on the diameter of the discharge hole 516. However, by forming the discharge hole 516 with a diameter larger than the width of the recess 532a or by controlling the position of the discharge hole 516, the recess 532a and the discharge hole 516 can be aligned in a straight line. That is, as... Figure 4 As shown, the gas emission path can be aligned with the electrode assembly 300 (see Figure 1). Figure 4 (The dashed arrow in the image). Therefore, the gas discharge path according to this embodiment differs from the gas discharge path through the existing perforation (…). Figure 4 Compared to the curved arrow in the image, this improves straightness, thereby shortening the gas discharge time.

[0058] exist Figure 3 In the embodiments described, an example of multiple discharge holes 516 being circular has been given, but the discharge holes 516 can also be elliptical, rectangular, or arc-shaped. Figure 5 As in the example, the discharge hole 516a can be in the form of an elongated hole. If it is elongated, the discharge hole 516a can be in the form of an arc-shaped slit. For example, based on the imaginary center point of the top cover 510a, the discharge hole 516a can be an elongated hole with an angle θ between its two ends of 10 degrees. However, the angle (θ or the length of the elongated hole) between the two ends of each discharge hole 516a can vary depending on the number and shape of the discharge holes 516a. For example, based on the imaginary center point of the top cover 510a, the discharge hole 516a can be located between the two ends of each through hole 512a ( Figure 6 Position B and / or Figure 7 Position C in the middle.

[0059] The diameter of the discharge hole (516, which will be described as a circular discharge hole for convenience) with the above structure can vary depending on the diameter of the upper part of the cover 510. (Refer to...) Figure 6 Describe the diameter of the top cover 510 and the diameter of the discharge hole 516.

[0060] For example, a cylindrical secondary battery with a diameter of 18-21Ø (pi) will be described by way of example. Here, the minimum diameter (D1) of the upper part of the cover 510 used for welding the busbar can be 6.5 pi. The minimum diameter of the notch 532a of the vent plate 530 that breaks when gas is discharged (i.e., the diameter D2 from the center point of the cover to the notch) can be 7 pi. The diameter of the notch 532a can be a minimum of 7 pi and a maximum of 9.5 pi. It is necessary to ensure the area for welding the busbar by placing the vent hole 516 outside the minimum diameter (D1) of the upper part of the cover 510. Therefore, the minimum diameter (D3) of the vent hole 516 can be 0.5 pi, and the maximum diameter (D4) of the vent hole 516 can be 1.15 pi. Depending on the diameter of the vent hole 516, the position of the vent hole 516 can overlap with the notch 532a, or it can not overlap with the notch 532a. If the position of the discharge hole 516 overlaps with the notch 532a, the gas discharge path becomes straight, and the gas discharge time can be shortened. However, even if the position of the discharge hole 516 does not overlap with the notch 532a, the gas discharge path is almost straight compared to the gas discharge path through the perforation 512, so the gas can still be discharged smoothly. The diameter of the upper part of the cover 510 and the diameter of the discharge hole 516 can vary according to the diameter of the cylindrical secondary battery.

[0061] While the foregoing embodiments are merely one example of implementing the secondary battery according to the present invention, they are not limited to this embodiment. However, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A cylindrical secondary battery, the cylindrical secondary battery comprising: Electrode assembly; A cylindrical container in which the electrode assembly is housed; as well as A cover assembly, coupled to the can, electrically connected to the electrode assembly, insulated from the can, and comprising: an upper cover exposed to the outside; a lower cover supporting the upper cover; an exhaust plate disposed between the upper cover and the lower cover, spaced apart from the lower cover and having at least one notch formed therein; and an insulator made of an insulating material and disposed between the lower cover and the exhaust plate. The top cover includes multiple perforations formed through the plate surface, multiple bridges arranged between the multiple perforations, and multiple discharge holes formed through the plate surface and spaced apart from the multiple perforations.

2. The cylindrical secondary battery according to claim 1, wherein, The top cover has a lower portion that contacts the exhaust plate and an upper portion that protrudes upward from the lower portion, and the plurality of perforations are formed at the boundary between the lower portion and the upper portion.

3. The cylindrical secondary battery according to claim 2, wherein, The plurality of discharge holes are formed in the upper part of the upper cover.

4. The cylindrical secondary battery according to claim 3, wherein, The plurality of discharge holes are formed along the upper edge of the top cover.

5. The cylindrical secondary battery according to claim 4, wherein, The plurality of discharge holes are one of the following: circular, elliptical, rectangular, and arc-shaped.

6. The cylindrical secondary battery according to claim 4, wherein, The plurality of discharge holes are disposed between the two ends of each of the plurality of perforations.

7. The cylindrical secondary battery according to claim 4, wherein, The plurality of discharge holes are formed on the outside of the minimum welding diameter region, in which the top cover is welded to the manifold.

8. The cylindrical secondary battery according to claim 4, wherein, The plurality of discharge holes are configured such that at least a portion of the plurality of discharge holes corresponds to the position of the at least one notch.

9. The cylindrical secondary battery according to claim 4, wherein, The plurality of discharge holes are stacked with the at least one recess.

10. A cylindrical secondary battery, the cylindrical secondary battery comprising: Electrode assembly; A cylindrical container in which the electrode assembly is housed; as well as A cover assembly, electrically connected to the electrode assembly, insulated from the can, and comprising: an upper cover exposed to the outside and having a plurality of perforations formed through the upper cover; a lower cover supporting the upper cover; an exhaust plate disposed between the upper cover and the lower cover, spaced apart from the lower cover, and having at least one notch formed therein; and an insulator made of an insulating material and disposed between the lower cover and the exhaust plate. The top cover has a double-hole structure, which has multiple discharge holes that are spaced apart from and pass through the multiple perforations.

11. The cylindrical secondary battery according to claim 10, wherein, The upper cover has a circular plate-shaped lower portion that contacts the exhaust plate and a circular plate-shaped upper portion that protrudes upward from the lower portion, and the plurality of perforations are formed at the boundary between the lower portion and the upper portion.

12. The cylindrical secondary battery according to claim 11, wherein, The plurality of discharge holes are formed along the upper edge of the top cover.

13. The cylindrical secondary battery according to claim 12, wherein, The plurality of discharge holes are one of the following: circular, elliptical, rectangular, and arc-shaped.

14. The cylindrical secondary battery according to claim 13, wherein, The plurality of discharge holes are disposed between the two ends of each of the plurality of perforations.

15. The cylindrical secondary battery according to claim 13, wherein, The plurality of discharge holes are formed on the outside of the minimum welding diameter region, in which the top cover is welded to the manifold.

16. The cylindrical secondary battery according to claim 13, wherein, The plurality of discharge holes are configured such that at least a portion of the plurality of discharge holes corresponds to the position of the at least one notch.

17. The cylindrical secondary battery according to claim 13, wherein, The plurality of discharge holes are stacked with the at least one recess.

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