Cap assembly and secondary battery including same

Abstract

The present disclosure relates to a cap assembly and a secondary battery including same. The technical problem to be solved is to provide a cap assembly capable of preventing deformation of a safety vent and a secondary battery including same. To this end, the present disclosure provides a cap assembly comprising: an upper cap; a lower cap disposed below the upper cap; a safety vent disposed between the upper cap and the lower cap; a stepped portion extending stepwise from the upper cap; and a bending portion extending from the safety vent and surrounding the stepped portion.

Description

Cap assembly and secondary battery including the same

[0001] The present disclosure relates to a cap assembly and a secondary battery including the same.

[0002] Secondary batteries, unlike non-rechargeable primary batteries, are rechargeable and dischargeable. Low-capacity secondary batteries are used in small, portable electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while large-capacity secondary batteries are widely used as power sources for motor drives and power storage in hybrid and electric vehicles. These secondary batteries include an electrode assembly comprising a positive and negative electrode, a case housing the electrode assembly, and electrode terminals connected to the electrode assembly.

[0003] The above-described information disclosed in the background technology of this invention is only intended to improve understanding of the background of the present invention, and therefore may include information that does not constitute prior art.

[0004] The purpose of the present invention is to provide a cap assembly capable of preventing deformation of a safety vent and a secondary battery including the same.

[0005] 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.

[0006] According to one embodiment of the present invention for solving the above technical problem, a cap assembly includes: a cap up, a cap down disposed below the cap up, a safety vent disposed between the cap up and the cap down, a step portion extending from the cap up, and a banding portion extending from the safety vent and surrounding the step portion.

[0007] The cap up includes an inner body, an outer body spaced apart from the inner body and in contact with the safety vent, and a bridge arranged between the inner body and the outer body, and the step portion can extend from the outer body.

[0008] The thickness of the above-mentioned step portion may be smaller than the thickness of the above-mentioned outer body.

[0009] The difference between the thickness of the outer body and the thickness of the step portion may be 0.1 mm to 0.15 mm.

[0010] The above-mentioned step portion may include a first step surface and a second step surface arranged to face in a direction opposite to the first step surface.

[0011] It may further include a third step surface extending obliquely from the first step surface toward the outer body.

[0012] The above first step surface can be arranged to face downward.

[0013] The above first step surface may be positioned higher than the lower surface of the outer body.

[0014] The above second step surface can be arranged at the same height as the upper surface of the outer body.

[0015] The length of the first step surface may be 2 mm to 3 mm.

[0016] The above-mentioned step portion may further include a protruding portion formed on at least one of the first step surface, the second step surface, and the third step surface.

[0017] The safety vent may include a vent plate coupled with the cap down and having a notch, and a connecting portion extending from the vent plate and in contact with the outer body.

[0018] The above-mentioned banding portion may include a first banding portion extending from the connecting portion and in contact with the first step surface, a second banding portion spaced apart from the first banding portion and in contact with the third step surface, and a connecting portion connecting the first banding portion and the second banding portion.

[0019] The first banding portion may include a bending portion extending in a bending manner from the joining portion.

[0020] The above-mentioned bending portion can be in contact with the third step surface.

[0021] A gap may be formed between the third step surface and the bending portion.

[0022] It may further include a first insulating member disposed between the safety vent and the cap down.

[0023] According to one embodiment of the present invention, a secondary battery includes: a can having an opening, an electrode assembly accommodated in the can, and a cap assembly covering the opening, wherein the cap assembly includes a cap up, a cap down disposed below the cap up, a safety vent disposed between the cap up and the cap down, a step portion extending from the cap up, and a banding portion extending from the safety vent and surrounding the step portion.

[0024] The above can may include a crimping portion that surrounds the banding portion.

[0025] It may further include a second insulating member disposed between the banding portion and the crimping portion.

[0026] According to the present invention, by applying a step structure to the lower edge of the cap up, the pressure applied to the safety vent during the crimping process of the cap assembly is distributed and supported, thereby preventing deformation of the safety vent.

[0027] However, the effects that can be obtained through the present invention are not limited to the effects described above, and other technical effects that are not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0028] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0029] FIG. 1 is a perspective view schematically showing the configuration of a secondary battery according to a first embodiment of the present invention.

[0030] Figure 2 is a cross-sectional view schematically showing the configuration of a secondary battery according to the first embodiment of the present invention.

[0031] Figure 3 is a partial cross-sectional view schematically showing the configuration of a secondary battery according to the first embodiment of the present invention.

[0032] Fig. 4 is a cross-sectional view schematically showing the configuration of a cap assembly according to the first embodiment of the present invention.

[0033] Fig. 5 is a partial cross-sectional view schematically showing the configuration of a cap assembly according to the first embodiment of the present invention.

[0034] Fig. 6 is a partial cross-sectional view schematically showing the configuration of a step portion in a cap assembly according to the first embodiment of the present invention.

[0035] Figure 7 is a cross-sectional view schematically showing the configuration of a secondary battery according to the second embodiment of the present invention.

[0036] Figure 8 is a partial cross-sectional view schematically showing the configuration of a secondary battery according to a second embodiment of the present invention.

[0037] Fig. 9 is a cross-sectional view schematically showing the configuration of a cap assembly according to a second embodiment of the present invention.

[0038] Fig. 10 is a partial cross-sectional view schematically showing the configuration of a cap assembly according to a second embodiment of the present invention.

[0039] Fig. 11 is a partial cross-sectional view schematically showing the configuration of a step portion in a cap assembly according to a second embodiment of the present invention.

[0040] Fig. 12 is a partial bottom view schematically showing the configuration of a step portion in a cap assembly according to a third embodiment of the present invention.

[0041] Fig. 13 is a partial cross-sectional view schematically showing the configuration of a cap assembly according to a third embodiment of the present invention.

[0042] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as substitutes for them at the time of filing this application.

[0043] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and / or groups thereof.

[0044] In addition, when describing embodiments of the present invention, “may be”, “may be” may include “one or more embodiments of the present invention.” In addition, to help understanding of the invention, the attached drawings may not be drawn to scale, but the dimensions of some components may be exaggerated. In addition, the same reference numbers may be given to the same components in different embodiments.

[0045] The statement that two compared objects are "identical" means "substantially identical." Therefore, "substantially identical" may include deviations considered low in the art, such as deviations of less than 5%. Furthermore, uniformity of a parameter over a given region may imply uniformity on average.

[0046] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0047] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0048] Any configuration being placed "on (or under)" or "above (or below)" a component may mean not only that any configuration is placed in contact with the upper surface (or lower surface) of said component, but also that other configurations may intervene between said component and any configuration placed on (or below) said component.

[0049] Additionally, when it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to each other, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through another component. Furthermore, when it is said that a part is electrically coupled to another part, this includes not only cases where they are directly connected, but also cases where they are connected with another element in between.

[0050] When reference is made throughout the specification to "A and / or B," this means A, B, or A and B, unless otherwise stated. In other words, "and / or" includes all or any combination of the listed items. When reference is made to "C through D," this means C or more and D or less, unless otherwise stated.

[0051] FIG. 1 is a perspective view schematically showing the configuration of a secondary battery according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view schematically showing the configuration of a secondary battery according to a first embodiment of the present invention, and FIG. 3 is a partial cross-sectional view schematically showing the configuration of a secondary battery according to a first embodiment of the present invention.

[0052] Referring to FIGS. 1 to 3, a secondary battery (1) according to the first embodiment of the present invention may include a can (100), an electrode assembly (200), and a cap assembly (300).

[0053] The can (100) may be formed in a hollow cylindrical shape. The can (100) may include a generally circular bottom portion (110) and a side wall portion (120) extending upward from the bottom portion (110) by a set length. The can (100) may be made of steel, a steel alloy, nickel-plated steel, a nickel-plated steel alloy, aluminum, or an aluminum alloy.

[0054] During the manufacturing process of the secondary battery (1) according to the first embodiment of the present invention, the upper portion of the can (100) may be opened. That is, an opening (100a) may be provided on the upper surface of the can (100). The opening (100a) may be formed by penetrating the upper surface of the can (100) in the vertical direction.

[0055] The electrode assembly (200) can be accommodated inside the can (100). During the assembly process of the secondary battery (1) according to the first embodiment of the present invention, the electrode assembly (200) can be integrated into a single structure and inserted into the can (100). Thereafter, an electrolyte can be additionally injected into the can (100).

[0056] A beading part (130) recessed in the direction of the central axis (C) of the can (100) may be formed on the upper part of the can (100) to prevent the electrode assembly (200) from being separated from the outside of the can (100) through the opening (100a).

[0057] The beading part (130) may be located on the lower side of the cap assembly (300). A crimping part (140) bent to wrap around the banding part (350) may be formed on the upper part of the beading part (130).

[0058] The electrode assembly (200) may include or be referred to as an electrode, an electrode group, or a jelly roll. The electrode assembly (200) may include a negative electrode plate (210) coated with a negative electrode active material (e.g., graphite, carbon, etc.), a positive electrode plate (220) coated with a positive electrode active material (e.g., a transition metal oxide (LiCoO2, LiNiO2, LiMn2O4, etc.)), and a separator (230) positioned between the negative electrode plate (210) and the positive electrode plate (220) to prevent short circuiting and allow only the movement of lithium ions.

[0059] The negative electrode plate (210), the positive electrode plate (220), and the separator (230) can be wound in a roughly cylindrical shape. The negative electrode plate (210) can be a copper (Cu) foil, the positive electrode plate (220) can be an aluminum (Al) foil, and the separator (230) can be polyethylene (PE) or polypropylene (PP).

[0060] A negative electrode tab (240) may be welded to the negative electrode plate (210). The negative electrode tab (240) may protrude and extend to the lower portion of the electrode assembly (200) by a set length. A positive electrode tab (250) may be welded to the positive electrode plate (220).

[0061] The positive electrode tab (250) may be extended to protrude a set length from the top of the electrode assembly (200). The negative electrode tab (240) may be copper (Cu) or nickel (Ni), and the positive electrode tab (250) may be aluminum (Al).

[0062] The negative tab (240) can be welded to the bottom (110) of the can (100). Therefore, the can (100) can operate as a negative electrode. The negative tab (240) can be ultrasonically or laser welded to the bottom (110) of the can (100). Of course, conversely, the positive tab (250) can be welded to the bottom (110) of the can (100), in which case the can (100) can operate as a positive electrode.

[0063] The electrode assembly (200) may further include a center pin (260). The center pin (260) is in the form of a hollow circular pipe and may be coupled to approximately the center of the electrode assembly (200). The center pin (260) may be formed of steel, stainless steel, aluminum, an aluminum alloy, or polybutylene terepthalate, but the material is not limited thereto.

[0064] The center pin (260) can suppress deformation of the electrode assembly (200) during charging and discharging of the electrode assembly (200). The center pin (260) can function as a passage for gas generated in the electrode assembly (200). In some cases, the center pin (260) may be omitted.

[0065] The cap assembly (300) can be coupled to the can (100) to cover the opening (100a). The cap assembly (300) can be fixed to the can (100) by a crimping portion (140). The cap assembly (300) can be electrically connected to the electrode assembly (200). The cap assembly (300) can seal the opening (100a) of the can (100) and protect the electrode assembly (200) from the external environment.

[0066] When the internal pressure of the can (100) rises above the set pressure due to thermal runaway or ignition of the electrode assembly (200), the cap assembly (300) may rupture, releasing the internal gas of the can (100) to the outside. The cap assembly (300) may serve as a positive terminal.

[0067] FIG. 4 is a cross-sectional view schematically showing the configuration of a cap assembly according to a first embodiment of the present invention, FIG. 5 is a partial cross-sectional view schematically showing the configuration of a cap assembly according to a first embodiment of the present invention, and FIG. 6 is a partial cross-sectional view schematically showing the configuration of a step portion in a cap assembly according to a first embodiment of the present invention.

[0068] Referring to FIGS. 1 to 6, a cap assembly (300) according to the first embodiment of the present invention may include a cap up (310), a safety vent (320), a cap down (330), a step portion (340), and a banding portion (350).

[0069] The cap up (310) can serve as a terminal electrically connected to an external device. The cap up (310) can serve as a positive terminal.

[0070] The cap up (310) may be provided with a first opening (310a). The first opening (310a) may serve to discharge internal gas to the outside when an abnormal internal pressure occurs within the can (100) due to overfilling or other reasons. The cap up (310) may be manufactured from aluminum or an aluminum alloy.

[0071] The cap up (310) may include an inner body (311), an outer body (312), and a bridge (313).

[0072] The inner body (311) can form the central outer appearance of the cap up (310). The inner body (311) can be formed to have a roughly circular shape. The inner body (311) can be arranged so that its central axis (C) is aligned with the central axis (C) of the can (100).

[0073] The outer body (312) may form the outer edge of the cap up (310). The outer body (312) may be in contact with the safety vent (320). The outer body (312) may be formed to have a substantially hollow ring shape. The diameter of the outer body (312) may be formed to be larger than the diameter of the inner body (311).

[0074] The outer body (312) can be arranged coaxially with the inner body (311). That is, the central axis (C) of the outer body (312) can be arranged to coincide with the central axis (C) of the inner body (311) and the central axis (C) of the can (100).

[0075] The inner body (311) and the outer body (312) may be arranged to be spaced apart from each other vertically. The outer body (312) may be arranged on the lower side of the inner body (311). Alternatively, the inner body (311) and the outer body (312) may also be arranged on the same plane.

[0076] The bridge (313) is placed between the inner body (311) and the outer body (312) and can support the inner body (311) with respect to the outer body (312). The bridge (313) can be formed so that each end has a rod shape connecting the outer surface of the inner body (311) and the inner surface of the outer body (312).

[0077] A plurality of bridges (313) may be provided. The plurality of bridges (313) may be spaced apart from each other along the circumference of the can (100) with the central axis (C) of the can (100) as the center. The spacing between adjacent bridges (313) may be the same, but is not limited thereto.

[0078] The first opening (310a) may be formed to have the shape of a hole that penetrates the cap up (310). The first opening (310a) may be formed to have the shape of a hole that penetrates the area between the inner body (311) and the outer body (312).

[0079] The first opening (310a) may be provided in multiple numbers. The multiple first openings (310a) may be individually positioned between adjacent bridges (313). The number of first openings (310a) is not limited to that illustrated in FIG. 1, and the design may be changed to a variety of numbers.

[0080] The safety vent (320) may be positioned between the cap up (310) and the cap down (330). The safety vent (320) may be in close contact with, in contact with, coupled with, or connected to the lower portion of the cap up (310).

[0081] The safety vent (320) can be in close contact with, in contact with, coupled with or connected to the edge of the cap up (310) excluding the center portion protruding upward from the cap up (310), i.e., the inner body (311), i.e., the outer body (312). The safety vent (320) can be made of aluminum or an aluminum alloy.

[0082] The safety vent (320) may include a vent plate (321) and a joint (322).

[0083] The vent plate (321) can be placed between the cap up (310) and the cap down (330). The vent plate (321) can be combined with the cap down (330). The lower surface of the central portion of the vent plate (321) can be in close contact with, in contact with, combined with, or connected to the upper surface of the central portion of the cap down (330).

[0084] The vent plate (321) may be provided with a notch (321a). A plurality of notches (321a) may be provided on the vent plate (321). The notches (321a) may be formed concavely to a set depth from the inner or outer surface of the vent plate (321), but are not limited thereto.

[0085] As the internal pressure of the can (100) rises above the reference pressure (or the rupture pressure of the safety vent (320)) due to thermal runaway or ignition of the electrode assembly (200), the notch (321a) is ruptured, and the exhaust generated inside the can (100) can sequentially pass through the second opening (330a) of the cap down (330), the notch (321a), and the first opening (310a) of the cap up (310) and be discharged to the outside. Here, the exhaust discharged from the first opening (310a) may include at least one of flame, gas, and smoke.

[0086] The connecting portion (322) may extend radially from the vent plate (321) to the can (100). The connecting portion (322) may be connected to the outer body (312). The upper surface of the connecting portion (322) and the lower surface of the outer body (312) may be in close contact with, in contact with, connected to, or connected to each other.

[0087] The step portion (340) can be extended stepwise from the cap up (310). The step portion (340) can be extended radially from the outer body (312) of the can (100).

[0088] The thickness (T) of the step portion (340) may be formed to be smaller than the thickness (T) of the outer body (312). The difference between the thickness (T) of the outer body (312) and the thickness (T) of the step portion (340) may be about 0.1 mm to about 0.15 mm.

[0089] As shown in [Table 1], if the difference between the thickness (T) of the outer body (312) and the thickness (T) of the step portion (340) is less than about 0.1 mm or more than about 0.15 mm, the safety vent (320) may be deformed during the crimping process of the cap assembly (300).

[0090] Thickness (mm) Difference deformation degree 0.05O0.1X0.15X0.2O

[0091] The step portion (340) may include a first step surface (341) and a second step surface (342). The first step surface (341) may be arranged to face downward. Here, downward may refer to the direction in which the can (100) is positioned. The first step surface (341) may be formed as a flat plane. The first step surface (341) may be arranged higher than the lower surface of the outer body (312). The length (L) of the first step surface (341) may be about 2 mm to about 3 mm. As shown in [Table 2], when the length (L) of the first step surface (341) is less than about 2 mm, the safety vent (320) may be deformed during the crimping process of the cap assembly (300).

[0092] Length (mm) Deformation degree Deformation amount 1.0O△0.081.5O△0.042.0X△0.022.5X△0.013.0X△0.00

[0093] The second step surface (342) may be arranged to face upward opposite to the first step surface (341). The second step surface (342) may be arranged at the same height as the upper surface of the outer body (312). The bending portion (350) may extend from the safety vent (320) and surround the step portion (340). The bending portion (350) may extend from the joining portion (322) in the radial direction of the can (100) to surround the step portion (340). The bending portion (323) may extend upwardly from the joining portion (322) in a curved manner to surround the step portion (340). The bending portion (350) may include a first bending portion (351), a second bending portion (352), and a connecting portion (353).

[0094] The first banding portion (351) can be formed to be in contact with the first step surface (341) of the step portion (340). The first banding portion (351) can be in close contact with the first step surface (341).

[0095] The second banding portion (352) may be formed to be spaced apart from the first banding portion (351) and to be in contact with the second step surface (342) of the step portion (340). The second banding portion (352) may be in close contact with the second step surface (342).

[0096] The connecting portion (353) can connect between the first banding portion (351) and the second banding portion (352). The connecting portion (353) is provided to be in contact with the free end of the step portion (340) and can connect one end of the first banding portion (351) and one end of the second banding portion (352).

[0097] The first banding portion (351) may further include a bending portion (351a). The bending portion (351a) may extend in a bending manner from the connecting portion (322). The bending portion (351a) may connect the connecting portion (322) and the first banding portion (351). The bending portion (351a) may be formed in a bending shape from the connecting portion (322) toward the first banding portion (351).

[0098] The cap down (330) may be positioned on the lower side of the cap up (310). The cap down (330) may be positioned on the lower side of the safety vent (320). The cap down (330) may be coupled to the safety vent (320). The cap down (330) may be provided with a second opening (330a). The second opening (330a) may be formed in the form of a hole formed by penetrating the cap down (330).

[0099] The second opening (330a) can serve to discharge internal gas to the outside when abnormal internal pressure occurs inside the can (100) due to overcharging or other reasons. The second opening (330a) can communicate with the first opening (310a) when the safety vent (320) is ruptured.

[0100] The upper surface of the central portion of the cap down (330) may be in close contact with, in contact with, coupled with, or connected to the lower surface of the central portion of the vent plate (321). The cap down (330) may be electrically connected to the electrode assembly (200) via the positive electrode tab (250). The cap down (330) may be electrically connected to the safety vent (320) and the cap up (310).

[0101] The positive electrode tab (250) of the electrode assembly (200) may be welded to the lower surface of the cap down (330). The lower surface of the cap down (330) may be ultrasonically and / or laser welded to the positive electrode tab (250). The cap down (330) may be made of aluminum or an aluminum alloy.

[0102] In the event of thermal runaway or ignition of the electrode assembly (200), the safety vent (320) is deformed by the internal pressure of the can (100), and the cap down (330) and the safety vent (320) can be electrically separated.

[0103] A first insulating member (360) may be installed between the safety vent (320) and the cap down (330). The first insulating member (360) may be located between the edge of the cap down (330) and the joint (322).

[0104] The first insulating member (360) can serve to insulate between the cap down (330) and the safety vent (320) when the safety vent (320) is deformed by the internal gas of the can (100). The first insulating member (360) can be formed of a resin material such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), etc., but the material is not limited thereto.

[0105] A second insulating member (400) may be installed on the upper part of the can (100). The second insulating member (400) may be installed between the banding member (350) surrounding the step member (340) and the crimping member (140).

[0106] The second insulating member (400) can be in close contact with the outer surface of the banding portion (350) and the inner surface of the crimping portion (140). The end of the second insulating member (400) can be in close contact with the inner surface of the beading portion (130).

[0107] The second insulating member (400) may serve to insulate between the can (100) and the cap assembly (300). The second insulating member (400) may be formed of a resin material such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), etc., but the material is not limited thereto.

[0108] FIG. 7 is a cross-sectional view schematically showing the configuration of a secondary battery according to a second embodiment of the present invention, FIG. 8 is a partial cross-sectional view schematically showing the configuration of a secondary battery according to a second embodiment of the present invention, FIG. 9 is a cross-sectional view schematically showing the configuration of a cap assembly according to a second embodiment of the present invention, FIG. 10 is a partial cross-sectional view schematically showing the configuration of a cap assembly according to a second embodiment of the present invention, and FIG. 11 is a partial cross-sectional view schematically showing the configuration of a step portion in a cap assembly according to a second embodiment of the present invention.

[0109] Referring to FIGS. 7 to 11, a secondary battery (1) according to a second embodiment of the present invention may include a can (100), an electrode assembly (200), and a cap assembly (300).

[0110] In describing the secondary battery (1) according to the second embodiment of the present invention, another embodiment of the cap assembly (300) described in the secondary battery (1) according to the first embodiment of the present invention will be described.

[0111] The description of the secondary battery (1) according to the first embodiment of the present invention can be applied as is to the remaining configuration of the secondary battery (1) according to the second embodiment of the present invention.

[0112] The cap assembly (300) may include a cap up (310), a safety vent (320), a cap down (330), a step portion (340), and a banding portion (350).

[0113] The cap up (310) may be provided with a first opening (310a). The first opening (310a) may serve to discharge internal gas to the outside when an abnormal internal pressure occurs inside the can (100) due to overcharging or other reasons.

[0114] The cap up (310) may include an inner body (311), an outer body (312), and a bridge (313).

[0115] The inner body (311) can form the central outer appearance of the cap up (310). The inner body (311) can be formed to have a roughly circular shape. The inner body (311) can be arranged so that its central axis (C) is aligned with the central axis (C) of the can (100).

[0116] The outer body (312) may form the outer edge of the cap up (310). The outer body (312) may be in contact with the safety vent (320). The outer body (312) may be formed to have a substantially hollow ring shape. The diameter of the outer body (312) may be formed to be larger than the diameter of the inner body (311).

[0117] The outer body (312) can be arranged coaxially with the inner body (311). That is, the central axis (C) of the outer body (312) can be arranged to coincide with the central axis (C) of the inner body (311) and the central axis (C) of the can (100).

[0118] The inner body (311) and the outer body (312) may be arranged to be spaced apart from each other vertically. The outer body (312) may be arranged on the lower side of the inner body (311). Alternatively, the inner body (311) and the outer body (312) may also be arranged on the same plane.

[0119] The bridge (313) is placed between the inner body (311) and the outer body (312) and can support the inner body (311) with respect to the outer body (312). The bridge (313) can be formed so that each end has a rod shape connecting the outer surface of the inner body (311) and the inner surface of the outer body (312).

[0120] A plurality of bridges (313) may be provided. The plurality of bridges (313) may be spaced apart from each other along the circumference of the can (100) with the central axis (C) of the can (100) as the center. The spacing between adjacent bridges (313) may be the same, but is not limited thereto.

[0121] The first opening (310a) may be formed to have the shape of a hole that penetrates the cap up (310). The first opening (310a) may be formed to have the shape of a hole that penetrates the area between the inner body (311) and the outer body (312).

[0122] The first opening (310a) may be provided in multiple numbers. The multiple first openings (310a) may be individually positioned between adjacent bridges (313). The number of first openings (310a) may be designed to vary.

[0123] The safety vent (320) may be positioned between the cap up (310) and the cap down (330). The safety vent (320) may be in close contact with, in contact with, coupled with, or connected to the lower portion of the cap up (310).

[0124] The safety vent (320) can be in close contact with, in contact with, coupled with or connected to the center portion protruding upward from the cap up (310), that is, the edge of the cap up (310) excluding the inner body (311), that is, the outer body (312).

[0125] The safety vent (320) may include a vent plate (321) and a joint (322).

[0126] The vent plate (321) can be placed between the cap up (310) and the cap down (330). The vent plate (321) can be combined with the cap down (330). The lower surface of the central portion of the vent plate (321) can be in close contact with, in contact with, combined with, or connected to the upper surface of the central portion of the cap down (330).

[0127] The vent plate (321) may be provided with a notch (321a). A plurality of notches (321a) may be provided on the vent plate (321). The notches (321a) may be formed concavely to a set depth from the inner or outer surface of the vent plate (321), but are not limited thereto.

[0128] As the internal pressure of the can (100) rises above the reference pressure (or the rupture pressure of the safety vent (320)) due to thermal runaway or ignition of the electrode assembly (200), the notch (321a) is ruptured, and the discharged matter generated inside the can (100) can sequentially pass through the second opening (330a) of the cap down (330), the notch (321a), and the first opening (310a) of the cap up (310) and be discharged to the outside.

[0129] The connecting portion (322) may extend radially from the vent plate (321) to the can (100). The connecting portion (322) may be connected to the outer body (312). The upper surface of the connecting portion (322) and the lower surface of the outer body (312) may be in close contact with, in contact with, connected to, or connected to each other.

[0130] The step portion (340) can be extended stepwise from the cap up (310). The step portion (340) can be extended radially from the outer body (312) of the can (100).

[0131] The thickness (T) of the step portion (340) may be formed to be smaller than the thickness (T) of the outer body (312). The difference between the thickness (T) of the outer body (312) and the thickness (T) of the step portion (340) may be about 0.1 mm to about 0.15 mm.

[0132] As shown in [Table 3], if the difference between the thickness (T) of the outer body (312) and the thickness (T) of the step portion (340) is less than about 0.1 mm or more than about 0.15 mm, the safety vent (320) may be deformed during the crimping process of the cap assembly (300).

[0133] Thickness (mm) Difference deformation degree 0.05O0.1X0.15X0.2O

[0134] The step portion (340) may include a first step surface (341), a second step surface (342), and a third step surface (343). The first step surface (341) may be arranged to face downward. Here, downward may refer to a direction in which the can (100) is positioned. The first step surface (341) may be formed as a flat plane. The first step surface (341) may be arranged higher than the lower surface of the outer body (312). The length (L) of the first step surface (341) may be about 2 mm to about 3 mm. As shown in [Table 4], when the length (L) of the first step surface (341) is less than about 2 mm, the safety vent (320) may be deformed during the crimping process of the cap assembly (300).

[0135] Length (mm) Deformation degree Deformation amount 1.0O△0.081.5O△0.042.0X△0.022.5X△0.013.0X△0.00

[0136] The second step surface (342) may be arranged to face upward opposite to the first step surface (341). The second step surface (342) may be arranged at the same height as the upper surface of the outer body (312). The third step surface (343) may be formed as an inclined surface inclined at a set angle. The third step surface (343) may extend downwardly from the first step surface (341) toward the outer body (312) in a slanted manner. The bending portion (350) may extend from the safety vent (320) and wrap around the step portion (340). The bending portion (350) may extend from the joining portion (322) in the radial direction of the can (100) and wrap around the step portion (340). The banding portion (323) can extend upwardly from the joining portion (322) to wrap around the step portion (340).

[0137] The banding portion (350) may include a first banding portion (351), a second banding portion (352), and a connecting portion (353).

[0138] The first banding portion (351) can be formed to be in contact with the first step surface (341) of the step portion (340). The first banding portion (351) can be in close contact with the first step surface (341).

[0139] The second banding portion (352) may be formed to be spaced apart from the first banding portion (351) and to be in contact with the second step surface (342) of the step portion (340). The second banding portion (352) may be in close contact with the second step surface (342).

[0140] The connecting portion (353) can connect between the first banding portion (351) and the second banding portion (352). The connecting portion (353) is provided to be in contact with the free end of the step portion (340) and can connect one end of the first banding portion (351) and one end of the second banding portion (352).

[0141] The first bending portion (351) may further include a bending portion (351a). The bending portion (351a) may extend in a bending manner from the connecting portion (322). The bending portion (351a) may connect the connecting portion (322) and the first bending portion (351). The bending portion (351a) may be formed in a shape that is bent upward at a set angle from the connecting portion (322) toward the first bending portion (351). The inclination angle of the bending portion (351a) may be the same as the inclination angle of the third step surface (343).

[0142] The bending portion (351a) may be in contact with the third step surface (343). A stress generation point may be formed at the area where the bending portion (351a) and the third step surface (343) come into contact, where stress is applied to the safety vent (320) during the crimping process of the cap assembly (300).

[0143] To elaborate, in the past, during the crimping process of the cap assembly (300), the stress generation point was formed at the edge of the cap assembly (300), but in the present invention, the stress generation point can be formed at the area where the bending portion (351a) and the third step surface (343) come into contact. That is, since the stress generation point is changed to a position closer to the central axis (C) of the cap assembly (300), the deformation amount of the safety vent (320) according to the deformation angle of the safety vent (320) can be reduced compared to the past.

[0144] The cap down (330) may be positioned on the lower side of the cap up (310). The cap down (330) may be positioned on the lower side of the safety vent (320). The cap down (330) may be coupled to the safety vent (320). The cap down (330) may be provided with a second opening (330a). The second opening (330a) may be formed in the form of a hole formed by penetrating the cap down (330).

[0145] The second opening (330a) can serve to discharge internal gas to the outside when abnormal internal pressure occurs inside the can (100) due to overcharging or other reasons. The second opening (330a) can communicate with the first opening (310a) when the safety vent (320) is ruptured.

[0146] The upper surface of the central portion of the cap down (330) may be in close contact with, in contact with, coupled with, or connected to the lower surface of the central portion of the vent plate (321). The cap down (330) may be electrically connected to the electrode assembly (200) via the positive electrode tab (250). The cap down (330) may be electrically connected to the safety vent (320) and the cap up (310).

[0147] The positive electrode tab (250) of the electrode assembly (200) can be welded to the lower surface of the cap down (330). In the event of thermal runaway or ignition of the electrode assembly (200), the safety vent (320) is deformed by the internal pressure of the can (100), and the cap down (330) and the safety vent (320) can be electrically separated.

[0148] Fig. 12 is a partial bottom view schematically showing the configuration of a step portion in a cap assembly according to a third embodiment of the present invention, and Fig. 13 is a partial cross-sectional view schematically showing the configuration of a cap assembly according to a third embodiment of the present invention.

[0149] Referring to Fig. 12, the step portion (340) may further include a recessed portion (344). The recessed portion (344) may be formed in the form of an embossing that protrudes from the surface of the step portion (340). The recessed portion (344) may be formed on at least one of the first step surface (341), the second step surface (342), and the third step surface (343).

[0150] By further including the uneven portion (344) in the step portion (340), the stress applied to the safety vent (320) during the crimping process of the cap assembly (300) for the can (100) can be supported, thereby preventing deformation of the safety vent (320).

[0151] Referring to Fig. 13, the bending portion (351a) may not be in contact with the third step surface (343). When the bending portion (351a) and the third step surface (343) are not in contact, a gap (G) may be formed between the third step surface (343) and the bending portion (351a).

[0152] Although the present invention has been described with reference to the embodiments shown in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom.

[0153] Therefore, the technical protection scope of the present invention should be defined by the following patent claims.

Claims

1. Cap up; A cap down positioned on the lower side of the above cap up; A safety vent positioned between the cap up and the cap down; a step portion extending in a stepwise manner from the above cap up; and A cap assembly characterized by including a banding portion extending from the safety vent and surrounding the step portion.

2. In paragraph 1, The above cap up is, Inner body; An outer body disposed apart from the inner body and in contact with the safety vent; and A bridge disposed between the inner body and the outer body; A cap assembly characterized in that the step portion extends from the outer body.

3. In paragraph 2, A cap assembly characterized in that the thickness of the step portion is smaller than the thickness of the outer body.

4. In paragraph 3, A cap assembly characterized in that the difference between the thickness of the outer body and the thickness of the step portion is 0.1 mm to 0.15 mm.

5. In paragraph 2, The above step part is, First step surface; and A cap assembly characterized by including a second step surface arranged to face in a direction opposite to the first step surface.

6. In paragraph 5, A cap assembly further comprising a third step surface extending obliquely from the first step surface toward the outer body.

7. In paragraph 6, A cap assembly characterized in that the first step surface is arranged to face downward.

8. In paragraph 7, A cap assembly characterized in that the first step surface is positioned higher than the lower surface of the outer body.

9. In paragraph 7, A cap assembly characterized in that the second step surface is arranged at the same height as the upper surface of the outer body.

10. In paragraph 7, A cap assembly, characterized in that the length of the first step surface is 2 mm to 3 mm.

11. In paragraph 6, A cap assembly characterized in that the step portion further includes a protruding portion formed on at least one of the first step surface, the second step surface, and the third step surface.

12. In paragraph 11, The above safety vent is, A vent plate coupled with the cap down and having a notch; and A cap assembly characterized by including a connecting portion extending from the vent plate and in contact with the outer body.

13. In paragraph 12, The above banding part, A first banding portion extending from the above-mentioned joint and in contact with the first step surface; A second banding portion spaced apart from the first banding portion and in contact with the third step surface; and A cap assembly characterized by including a connecting portion connecting the first banding portion and the second banding portion.

14. In paragraph 13, A cap assembly characterized in that the first banding portion includes a bending portion extending in a bending manner from the joining portion.

15. In paragraph 14, A cap assembly characterized in that the above-mentioned bending portion is in contact with the third step surface.

16. In paragraph 14, A cap assembly characterized in that a gap is formed between the third step surface and the bending portion.

17. In paragraph 1, A cap assembly further comprising a first insulating member disposed between the safety vent and the cap down.

18. A can having an opening; An electrode assembly accommodated in the can; and A cap assembly covering the above opening; The above cap assembly, cap up; A cap down positioned on the lower side of the above cap up; A safety vent positioned between the cap up and the cap down; a step portion extending in a stepwise manner from the above cap up; and A secondary battery characterized by including a banding portion extending from the safety vent and surrounding the step portion.

19. In paragraph 18, A secondary battery characterized in that the can includes a crimping portion that wraps the banding portion.

20. In paragraph 19, A secondary battery further comprising a second insulating member disposed between the banding portion and the crimping portion.

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