Cylinder type rechargeable battery

Abstract

The cylinder type rechargeable battery of the present invention comprises: a can including an inner space and an opening; an electrode assembly accommodated in the inner space of the can; and a cap assembly coupled to the can, sealing the opening, and including a cap-up and a safety vent disposed under the cap-up, wherein the distance between the uppermost portion of the cap-up and the safety vent is within a range of 1.6mm to 1.8mm.

Description

cylindrical secondary battery

[0001] The present invention relates to a cylindrical secondary battery.

[0002] Secondary batteries, unlike primary batteries that cannot be recharged, are batteries that can be charged and discharged. Low-capacity batteries with one electrode assembly packaged in a pack form are used in small portable electronic devices such as mobile phones and camcorders, and large-capacity batteries with dozens of electrode assemblies connected are widely used as power sources for driving motors in electric scooters, hybrid cars, and electric vehicles.

[0003] Secondary batteries are manufactured in various shapes, among which a cylindrical secondary battery includes an electrode assembly, a cylindrical can that accommodates the electrode assembly and an electrolyte, and a cap assembly that is joined to the upper opening of the can to seal the can and allow current generated from the electrode assembly to flow to an external device.

[0004] The safety vent included in the cap assembly can tear when exposed to gas generated within the secondary battery, allowing the gas to pass through. However, if the space within the cap assembly is insufficient, the safety vent may interfere with the cap assembly, preventing it from tearing smoothly and preventing the gas from passing through. Alternatively, the cap assembly may become deformed as the safety vent contacts it.

[0005] The present invention is intended to overcome the above-described conventional problems, and an object of the present invention is to provide a cylindrical secondary battery capable of preventing interference between a safety vent and a cap-up.

[0006] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0007] According to one embodiment of the present invention for solving the above technical problem, a cylindrical secondary battery includes a can including an internal space and an opening, an electrode assembly accommodated in the internal space of the can, and a cap assembly coupled to the can and sealing the opening, wherein the cap assembly includes a cap-up and a safety vent positioned at a lower portion of the cap-up, and the cap-up includes a coupling portion coupled to the safety vent, a protrusion positioned inwardly with respect to the coupling portion and protruding outward, and a connecting portion connecting the coupling portion and the protrusion, wherein a thickness of the protrusion portion is made relatively thinner than a thickness of the coupling portion.

[0008] The distance between the top of the cap-up and the safety vent may be in the range of 1.6 mm to 1.8 mm.

[0009] The vertical distance from the lowermost side of the above-mentioned joint to the lower side of the above-mentioned protrusion may be within the range of 1.3 mm to 1.4 mm.

[0010] The radius of curvature of the portion adjacent to the joint on the upper surface of the connecting portion of the above cap-up may exceed 0.5 mm.

[0011] The above connecting portion may have a thickness that increases from the protrusion to the joining portion.

[0012] The safety vent may include a vent contact portion that comes into contact with the cap-up, a vent slope portion that is inclined downward from the vent contact portion, a vent bottom portion that extends from the vent slope portion and is arranged parallel to the vent contact portion, and a vent protrusion portion that protrudes in one direction from the vent bottom portion.

[0013] The distance between the protrusion of the cap-up and the vent protrusion of the safety vent may be in the range of 1.6 mm to 1.8 mm.

[0014] The connection portion of the above cap-up may have one or more gas penetration holes.

[0015] The cylindrical secondary battery according to the present invention can secure sufficient space between the cap-up and the safety vent. Therefore, the safety vent can be smoothly deformed by gas within the can, and the gas can pass through the safety vent and be discharged to the outside through the gas penetration hole. Furthermore, deformation of the cap-up due to contact between the safety vent and the cap-up can be prevented.

[0016] In addition, in a cylindrical secondary battery according to one embodiment of the present invention, the connecting portion of the cap-up (141) may have a thickness that increases from the protrusion to the joining portion. Accordingly, the cap-up can be prevented from being deformed due to stress during the crimping process.

[0017] In addition, the cylindrical secondary battery according to one embodiment of the present invention is configured such that the radius of curvature of the upper surface of the cap-up connection portion adjacent to the joint portion exceeds 0.5 mm. Therefore, the cylindrical secondary battery according to one embodiment of the present invention can prevent the cap-up from being deformed during the crimping process.

[0018] FIG. 1 is a perspective view illustrating a cylindrical secondary battery according to one embodiment of the present invention.

[0019] Figure 2 is an exploded perspective view illustrating the cylindrical secondary battery of Figure 1.

[0020] Figure 3 is a cross-sectional view illustrating the cylindrical secondary battery of Figure 1.

[0021] Fig. 4 is a cross-sectional view illustrating the cap-up, safety vent, and cap-down of the cylindrical secondary battery of Fig. 3.

[0022] Figure 5 is a cross-sectional view showing the process of manufacturing a cap-up by pressing using a forging method.

[0023] FIG. 6 is a photograph of a cylindrical secondary battery according to one embodiment of the present invention, cut out and taken of some parts.

[0024] Fig. 7 is a photograph showing the safety vent of the cylindrical secondary battery of Fig. 6 deformed by internal gas.

[0025] Figure 8 is a photograph showing a state in which a safety vent of a cylindrical secondary battery according to a comparative example is deformed by internal gas.

[0026] The embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. The following embodiments may be modified in various ways, and the scope of the present invention is not limited to the embodiments described below. Rather, these embodiments are provided to more faithfully and completely explain the present disclosure and fully convey the spirit of the present invention to those skilled in the art.

[0027] In addition, in the drawings below, the thickness and size of each layer are exaggerated for convenience and clarity of explanation, and the same reference numerals in the drawings indicate the same elements. As used herein, the term "and / or" includes any one and all combinations of one or more of the listed items. In addition, the meaning of "connected" in this specification means not only when member A and member B are directly connected, but also when member C is interposed between member A and member B, so that member A and member B are indirectly connected.

[0028] The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the present invention. As used herein, the singular forms "a," "an," and "the" may include the plural forms unless the context clearly dictates otherwise. Furthermore, as used herein, the words "comprise" and "include" and / or "comprising" and "including" specify the presence of stated features, numbers, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, components, and / or groups thereof.

[0029] Although the terms first, second, etc. are used herein to describe various elements, components, regions, layers, and / or portions, it is to be understood that these elements, components, regions, layers, and / or portions are not limited by these terms. These terms are only used to distinguish one element, component, region, layer, or portion from another element, layer, or portion. Accordingly, a first element, component, region, layer, or portion described below may also refer to a second element, component, region, layer, or portion without departing from the teachings of the present invention.

[0030] In addition, terms related to space, such as "beneath," "below," "lower," "above," and "upper," may be used to facilitate understanding of one element or feature depicted in the drawings and other elements or features. These terms related to space are provided to facilitate understanding of the present invention in various process states or usage states, and are not intended to limit the present invention. For example, if an element or feature in the drawing is flipped, an element or feature described as "beneath" or "below" becomes "above" or "above." Therefore, "below" is a concept that encompasses "upper" or "below."

[0031] Hereinafter, a cylindrical secondary battery according to an embodiment of the present invention will be described in detail with reference to the attached drawings.

[0032] FIG. 1 is a perspective view illustrating a secondary battery according to one embodiment of the present invention, FIG. 3 is an exploded perspective view illustrating the cylindrical secondary battery of FIG. 1, and FIG. 2 is a cross-sectional view illustrating the cylindrical secondary battery of FIG. 1.

[0033] As illustrated in FIGS. 1 to 3, a cylindrical secondary battery (100) according to one embodiment of the present invention includes a can (110), an electrode assembly (120), and a cap assembly (140).

[0034] The can (110) may include a circular bottom portion (111) and a cylindrical side portion (112) extending upward from the bottom portion (111) by a certain length. During the manufacturing process of the cylindrical secondary battery (100), the top of the can (110) is open. Therefore, during the assembly process of the cylindrical secondary battery, the electrode assembly (120) may be inserted into the can (110) together with the electrolyte. For this purpose, the can (110) may include an opening.

[0035] The can (110) may include steel, a steel alloy, aluminum, an aluminum alloy, or an equivalent thereof. The can (110) may have a beading part (113) sunken inwardly at the bottom thereof centered around the cap assembly (140) to prevent the electrode assembly (120) and the cap assembly (140) from being detached to the outside, and may have a crimping part (114) bent inwardly at the top thereof.

[0036] An electrode assembly (120) can be accommodated inside a can (110). The electrode assembly (120) can include a negative electrode plate (121) coated with a negative electrode active material (e.g., graphite, carbon, etc.), a positive electrode plate (122) coated with a positive electrode active material (e.g., transition metal oxide (LiCoO2, LiNiO2, LiMn2O4, etc.)), and a separator (123) positioned between the negative electrode plate (121) and the positive electrode plate (122) to prevent short circuit and allow only the movement of lithium ions.

[0037] The negative electrode plate (121), the positive electrode plate (122), and the separator (123) can be wound in a roughly cylindrical shape. The negative electrode plate (121) can include copper (Cu) or nickel (Ni) foil, the positive electrode plate (122) can include aluminum (Al) foil, and the separator (123) can include polyethylene (PE) or polypropylene (PP).

[0038] A negative electrode tab (124) that protrudes downward by a certain length may be welded to the negative electrode plate (121), and a positive electrode tab (125) that protrudes upward by a certain length may be welded to the positive electrode plate (122), but the opposite is also possible. The negative electrode tab (124) may include a copper or nickel material, and the positive electrode tab (125) may include an aluminum material.

[0039] The negative tab (124) of the electrode assembly (120) can be welded to the bottom (111) of the can (110). Therefore, the can (110) can operate as a negative electrode. Of course, conversely, the positive tab (125) can be welded to the bottom (111) of the can (110), in which case the can (110) can operate as a positive electrode.

[0040] A first insulating plate (126) may be interposed between the electrode assembly (120) and the bottom portion (111). The first insulating plate (126) is coupled to the can (110) and has a first hole (126a) in the center and a second hole (126b) on the outside thereof. This first insulating plate (126) may prevent the electrode assembly (120) from electrically contacting the bottom portion (111) of the can (110).

[0041] The first insulating plate (126) can prevent the positive electrode plate (122) of the electrode assembly (120) from making electrical contact with the bottom portion (111). The first hole (126a) can allow the gas to quickly move upward through the center pin (130) when a large amount of gas is generated due to an abnormality in the cylindrical secondary battery. In addition, the negative electrode tab (124) can be welded to the bottom portion (111) by penetrating the second hole (126b).

[0042] A second insulating plate (127) can be interposed between the electrode assembly (120) and the cap assembly (140). The second insulating plate (127) is coupled to the can (110) and has a first hole (127a) in the center and a plurality of second holes (127b) on the outside thereof.

[0043] This second insulating plate (127) can prevent the electrode assembly (120) from making electrical contact with the cap assembly (140). The second insulating plate (127) can limit the electrical contact of the negative electrode plate (121) of the electrode assembly (120) with the cap assembly (140).

[0044] The first hole (127a) can allow the gas to quickly move to the cap assembly (140) when a large amount of gas is generated due to an abnormality in the cylindrical secondary battery, and the second hole (127b) can allow the positive electrode tab (125) to pass through and be welded to the cap assembly (140). In addition, the remaining second hole (127b) can allow the electrolyte to quickly flow into the electrode assembly (120) during the electrolyte injection process.

[0045] Meanwhile, the diameter of each of the first hole (126a) of the first insulating plate (126) and the first hole (127a) of the second insulating plate (127) may be smaller than the diameter of the center pin (130). Accordingly, the center pin (130) can be prevented from electrically contacting the bottom portion (111) of the can (110) or the cap assembly (140) due to external impact.

[0046] The center pin (130) is a hollow, circular pipe shape and can be joined approximately at the center of the electrode assembly (120). The center pin (130) can include steel, steel alloy, aluminum, aluminum alloy, or polybutylene terepthalate.

[0047] This center pin (130) serves to suppress deformation of the electrode assembly (120) during charging and discharging of the battery, and acts as a passage for gas generated inside the cylindrical secondary battery. In some cases, the center pin (130) may be omitted.

[0048] A cap assembly (140) is coupled to the can (110) and seals the opening of the can (110). The cap assembly (140) includes a cap-up (141) and a safety vent (142) located at the bottom of the cap-up (141). One or more gas penetration holes (141e) may be present in the cap-up (141). These gas penetration holes (141e) may allow gases that may be generated inside the can (110) to be discharged to the outside.

[0049] In addition, the cap assembly (140) may include a connecting ring (143) positioned below the safety vent (142), a cap-down (144) positioned below the safety vent (142) and the connecting ring (143) and including a plurality of through holes (144a), and electrically connected to the positive tab (125). The cap-down (144) is positioned on the opposite side of the cap-up (141) with the safety vent (142) interposed therebetween. In addition, the cap assembly (140) may further include an insulating gasket (145).

[0050] An insulating gasket (145) insulates the cap-up (141), the safety vent (142), and the cap-down (144) from the side (112) of the can (110). This insulating gasket (145) can be substantially compressed between the beading portion (113) and the crimping portion (114) included in the side (112) of the can (110).

[0051] The through hole (141a) of the cap-up (141) and the through hole (144a) of the cap-down (144) can discharge internal gas to the outside when an abnormal internal pressure occurs inside the can (110). The internal gas inverts the safety vent (142) upward through the through hole (144a) of the cap-down (144). At this time, the safety vent (142) is electrically separated from the cap-down (144). Then, when the safety vent (142) is torn, the internal gas can be discharged to the outside through the through hole (141a) of the cap-up (141).

[0052] An electrolyte (not shown in the drawing) may be poured into the inside of the can (110), which allows lithium ions generated by an electrochemical reaction in the negative electrode plate (121) and positive electrode plate (122) inside the battery to move during charging and discharging. This electrolyte may include a non-aqueous organic electrolyte that is a mixture of a lithium salt and a high-purity organic solvent. The electrolyte may include a polymer or solid electrolyte using a polymer electrolyte.

[0053] Meanwhile, the cylindrical secondary battery (100) according to one embodiment of the present invention is not necessarily limited to having the configuration described above, and may be applied to cylindrical secondary batteries having various structures including a cap-up (141) and a safety vent (142).

[0054] Hereinafter, a cap assembly (140) included in a cylindrical secondary battery (100) according to one embodiment of the present invention will be described in more detail with reference to the drawings.

[0055] FIG. 3 is a cross-sectional view illustrating the cylindrical secondary battery of FIG. 1, and FIG. 4 is a cross-sectional view illustrating the cap-up, safety vent, and cap-down extracted from the cylindrical secondary battery of FIG. 3.

[0056] Referring to FIGS. 3 and 4, a cap-up (141) included in a cap assembly (140) included in a cylindrical secondary battery (100) according to one embodiment of the present invention will be described in more detail. The cap-up (141) may include a coupling portion (141a), a protrusion portion (141b), and a connection portion (141c).

[0057] The connecting portion (141a) is connected to the safety vent (142). The connecting portion (141a) may be an edge portion of the cap-up (141). The edge portion of the safety vent (142), which will be described later, may be bent multiple times to connect to the connecting portion (141a). The safety vent (142) and the connecting portion (141a) may be more strongly connected using a welding method or an adhesive material.

[0058] The protrusion (141b) is positioned on the inside of the connecting portion (141a) and may protrude outward. The protrusion (141b) may be the central portion of the cap-up (141). The protrusion (141b) may be arranged parallel to the connecting portion (141a).

[0059] The connecting portion (141c) connects the connecting portion (141a) and the protrusion (141b). The shape of the vertical cross-section of the portion connected to each of the connecting portion (141a) and the protrusion (141b) in the connecting portion (141c) may be a round shape.

[0060] Meanwhile, in order to ensure sufficient space between the cap-up (141) and the safety vent (142), the thickness (T1) of the protrusion (141b) may be made relatively thinner than the thickness (T2) of the connecting portion (141a).

[0061] In addition, in the cap-up (141) as described above, the vertical distance (D2) from the lowermost side of the connecting portion (141a) to the lower side of the protrusion (141b) may be within a range of 1.3 mm to 1.4 mm. Accordingly, even if the safety vent (142) is deformed by gas, sufficient space can be secured between the cap-up (141) and the safety vent (142).

[0062] Meanwhile, if the safety vent deforms and comes into contact with the cap-up, the safety vent may not deform sufficiently to tear a portion of the safety vent. Consequently, gas may not be released to the outside through the cap-up's penetration hole. Furthermore, the cap-up may deform as the safety vent comes into contact with it.

[0063] On the other hand, in the cylindrical secondary battery (100) according to one embodiment of the present invention, sufficient space is secured between the cap-up (141) and the safety vent (142).

[0064] The gas generated inside the cylindrical secondary battery (100) deforms the safety vent (142) upward through the through hole (144a) of the cap down (144). At this time, the safety vent (142) is electrically separated from the cap down (144), and then a portion of the safety vent (142) is torn (opened), allowing the gas to be released to the outside through the through hole (141a) of the cap up (141). At this time, the safety vent (142) does not interfere with the cap up (141).

[0065] Meanwhile, to ensure sufficient space between the cap-up (141) and the safety vent (142), the cap-up (141) can be manufactured by a forging process. The forging process is a process of manufacturing metal using pressing or rolling, and the cap-up (141) can be manufactured by pressing a plate.

[0066] Referring to Fig. 5, as the cap-up (141) is pressed by a press (not shown), the thickness of the protrusion (141b) is gradually reduced. Accordingly, when examining the shape of the final vertical cross-section of the cap-up (141), the thickness of the protrusion (141b) (T1, see Fig. 4) becomes relatively thinner than the thickness of the connecting portion (141a) (T2, see Fig. 4). Accordingly, the space between the cap-up (141) and the safety vent (142, see Fig. 4) can be secured to the maximum extent.

[0067] FIG. 6 is a photograph of a cylindrical secondary battery according to one embodiment of the present invention, cut out and taken of some parts.

[0068] Referring to FIG. 6, the distance (D1) between the uppermost portion of the cap-up (141) and the safety vent (142) may be within the range of 1.6 mm to 1.8 mm.

[0069] Fig. 7 is a photograph showing the safety vent of the cylindrical secondary battery of Fig. 6 deformed by internal gas.

[0070] As shown in Fig. 7, when the distance (D1) between the uppermost part of the cap-up (141) and the safety vent (142) is within the range of 1.6 mm to 1.8 mm, even if the safety vent (142) is deformed, it is possible to prevent it from coming into contact (interfering) with the cap-up (141).

[0071] Figure 8 is a photograph showing a state in which a safety vent of a cylindrical secondary battery according to a comparative example is deformed by internal gas.

[0072] As shown in Fig. 8, in the case of a cylindrical secondary battery according to a comparative example manufactured so that the distance between the uppermost part of the cap-up (141) and the safety vent (142) is less than 1.6 mm, the safety vent (142) may interfere with the cap-up (141) as it deforms.

[0073] And, although not shown in the drawing, in the case of a cylindrical secondary battery manufactured so that the distance between the top of the cap-up and the safety vent exceeds 1.8 mm, the length of the secondary battery may become excessively long.

[0074] Meanwhile, returning to FIG. 4, the aforementioned safety vent (142) may include, for example, a vent contact portion (142a) that comes into contact with the cap-up (141), a vent slope portion (142b) that is inclined downward from the vent contact portion (142a), a vent bottom portion (142c) that extends from the vent slope portion (142b) and is arranged parallel to the vent contact portion (142a), and a vent protrusion portion (142d) that protrudes in one direction from the vent bottom portion (142c).

[0075] Here, the vent contact portion (142a) can be folded multiple times to contact the lower surface, side surface, and upper surface of the cap-up (141), respectively. In addition, the vent bottom portion (142c) can contact (connect or be connected to) the cap-down (144). Since such a safety vent (142) has been described above, a detailed description thereof will be omitted.

[0076] Meanwhile, as previously described, the distance between the protrusion (141b) of the cap-up (141) and the vent protrusion (142d) of the safety vent (142) may be within a range of 1.6 mm to 1.8 mm. Since the numerical limitation of the distance between the protrusion (141b) and the vent protrusion (142d) has been described previously, a detailed description thereof will be omitted.

[0077] Meanwhile, in the assembly process of a cylindrical secondary battery (100) according to one embodiment of the present invention, a crimping process may be performed. The crimping process is a finishing process for assembling a cylindrical secondary battery, which includes an insulating gasket (145) and various safety devices (PTC, Safety Vent, Current Break), etc., to pressurize and seal a portion of the cylindrical secondary battery together with the can, and then press.

[0078] During the crimping process, a significant amount of pressure may be applied to the cap-up (141). For example, the pressure applied to the cap-up (141) may be approximately 10 kgf.

[0079] In a cylindrical secondary battery (100) according to one embodiment of the present invention, the thickness of the connecting portion (141c) of the cap-up (141) may increase from the protrusion (141b) to the joining portion (141a). In addition, the radius of curvature (R) of the portion adjacent to the joining portion (141a) on the upper surface of the connecting portion (141c) of the cap-up (141) may be set to exceed 0.5 mm.

[0080] A portion adjacent to the joining portion (141a) in the connecting portion (141c) may be subjected to relatively greater stress during the crimping process compared to other portions. In the cylindrical secondary battery (100) according to one embodiment of the present invention, the thickness of the portion adjacent to the joining portion (141a) in the connecting portion (141c) is made relatively thick, thereby preventing deformation of the cap-up (141) due to stress.

[0081] Unlike the above, in the case of a secondary battery manufactured in which the radius of curvature (R) of the portion adjacent to the connecting portion (141a) on the upper surface of the connecting portion (141c) of the cap-up (141) is less than 0.5 mm, the cap-up (141) may be deformed during the crimping process. Here, the deformity of the cap-up (141) means that the portion adjacent to the connecting portion (141c) at the connecting portion (141a) is bent downward based on the direction illustrated in FIG. 4.

[0082] In a secondary battery according to a comparative example, in which the radius of curvature (R) of the portion adjacent to the connecting portion (141a) on the upper surface of the connecting portion (141c) of the cap-up (141) was 0.4 mm, the portion adjacent to the connecting portion (141c) of the connecting portion (141a) of the cap-up (141) was deformed by 1.01 mm.

[0083] And, in the secondary battery according to the comparative example manufactured with a radius of curvature (R) of 0.3 mm at the upper surface of the connecting portion (141c) of the cap-up (141) and the portion adjacent to the connecting portion (141a), the portion adjacent to the connecting portion (141c) of the connecting portion (141a) of the cap-up (141) was deformed by 1.2 mm.

[0084] On the other hand, in the secondary battery (100) according to the embodiment manufactured with a radius of curvature (R) of 0.7 mm at the upper surface of the connecting portion (141c) of the cap-up (141) and the portion adjacent to the connecting portion (141a), the portion adjacent to the connecting portion (141c) of the connecting portion (141a) of the cap-up (141) was very finely deformed by 0.1 mm.

[0085] And, in the secondary battery (100) according to the embodiment manufactured with a radius of curvature (R) of 1.03 mm at the upper surface of the connecting portion (141c) of the cap-up (141) and the portion adjacent to the connecting portion (141a), the portion adjacent to the connecting portion (141c) of the connecting portion (141a) of the cap-up (141) was hardly deformed by 0.05 mm.

[0086] As described above, the cylindrical secondary battery (100) according to one embodiment of the present invention is formed so that the radius of curvature (R) of the portion adjacent to the coupling portion (141a) on the upper surface of the connecting portion (141c) of the cap-up (141) exceeds 0.5 mm. Therefore, the cylindrical secondary battery (100) according to one embodiment of the present invention can prevent the cap-up (141) from being deformed during the crimping process.

[0087] According to one embodiment of the present invention, a cylindrical secondary battery (100) can ensure sufficient space between the cap-up (141) and the safety vent (142). Accordingly, the safety vent (142) can be smoothly deformed by the gas inside the can (110), and the gas can pass through the safety vent (142) and be discharged to the outside through the gas penetration hole (141e). In addition, deformation of the cap-up (141) due to the safety vent (142) coming into contact with the cap-up can be prevented.

[0088] In addition, in the cylindrical secondary battery (100) according to one embodiment of the present invention, the connecting portion (141c) of the cap-up (141) may have a thickness that increases from the protrusion (141b) to the joining portion (141a). Accordingly, the cap-up (141) can be prevented from being deformed due to stress during the crimping process.

[0089] In addition, the cylindrical secondary battery (100) according to one embodiment of the present invention is configured such that the radius of curvature (R) of the portion adjacent to the coupling portion (141a) on the upper surface of the connecting portion (141c) of the cap-up (141) exceeds 0.5 mm. Therefore, the cylindrical secondary battery (100) according to one embodiment of the present invention can prevent the cap-up (141) from being deformed during the crimping process.

[0090] While various embodiments of the present invention have been described above, the drawings and detailed description of the invention described so far are merely illustrative of the present invention, and are used solely for the purpose of explaining the present invention and are not intended to limit the meaning or scope of the present invention as set forth in the claims. Therefore, those skilled in the art will understand that various modifications and equivalent embodiments are possible. Accordingly, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

[0091] - Explanation of symbols -

[0092] 100: Cylindrical secondary battery

[0093] 110; can

[0094] 120; electrode assembly

[0095] 140: Cap assembly

[0096] 141: Cap Up

[0097] 141a: Joint

[0098] 141b: Protrusion

[0099] 141c: Connection

[0100] 142: Safety vent

Claims

1. A can containing an inner space and having an opening; An electrode assembly accommodated in the internal space of the can; and A cap assembly coupled to the can and sealing the opening; The above cap assembly, Cap up; and A safety vent located at the bottom of the cap-up; The above cap-up is, A joint that is coupled with the above safety vent; A protrusion positioned on the inside of the above-mentioned joint and protruding outward; and A connecting portion connecting the above-mentioned joint portion and the above-mentioned protrusion portion; A cylindrical secondary battery in which the thickness of the protrusion is thinner than the thickness of the connecting portion.

2. In paragraph 1, A cylindrical secondary battery, wherein the distance between the top of the cap-up and the safety vent is in the range of 1.6 mm to 1.8 mm.

3. In paragraph 1, A cylindrical secondary battery, wherein the vertical distance from the lowermost side of the above-mentioned joint to the lower side of the above-mentioned protrusion is in the range of 1.3 mm to 1.4 mm.

4. In paragraph 1, A cylindrical secondary battery having a radius of curvature of a portion adjacent to the joint portion on the upper surface of the connecting portion of the cap-up exceeding 0.5 mm.

5. In paragraph 1, The above connecting portion is a cylindrical secondary battery in which the thickness increases from the protrusion to the joining portion.

6. In paragraph 1, The above safety vent is, A vent contact portion that comes into contact with the above cap-up; A vent slope that slopes downward from the above vent contact portion; A vent bottom portion extending from the above vent slope and arranged parallel to the above vent contact portion; and A cylindrical secondary battery comprising a vent protrusion protruding in one direction from the vent bottom.

7. In paragraph 5, A cylindrical secondary battery, wherein the distance between the protrusion of the cap-up and the vent protrusion of the safety vent is in the range of 1.6 mm to 1.8 mm.

8. In paragraph 1, A cylindrical secondary battery having one or more gas penetration holes in the connecting portion of the above cap-up.

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