Secondary battery

Abstract

The present invention provides a secondary battery (10) comprising: an electrode assembly (100); a case (200) which accommodates the electrode assembly (100) and is open toward one side in a first direction; and a cap assembly (300) covering an end portion on the one side of the case (200) in the first direction. The cap assembly (300) may comprise: a cap plate (310) including an exhaust port (312); and a plate-shaped vent member (320) which is disposed on the opposite side to the cap plate (310) in the first direction and has a plurality of notch portions (N) each having a notch, wherein the plurality of notch portions (N) can fracture when the internal pressure of the case (200) reaches or exceeds a first threshold value. The plurality of notch portions (N) are positioned along the circumferential direction surrounding a first portion (322) of the vent member (320) and may be spaced a predetermined distance apart from each other. Each of the notch portions (N) may include: a pair of side portions (N1) extending outward from the first portion (322) and spaced apart from each other; and an outer portion (N2) connecting the outer ends of the pair of side portions (N1) and partially surrounding the first portion (322).

Description

secondary batteries

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0191918, dated December 26, 2023, and Korean Patent Application No. 10-2024-0192195, dated December 20, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a secondary battery, and more particularly, to a secondary battery in which gas or heat generated inside is discharged quickly and uniformly, thereby improving safety and increasing or miniaturizing battery capacity.

[0003] Secondary batteries are widely used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) that are powered by electrical power sources. Types of secondary batteries include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries.

[0004] Secondary batteries can generate internal gas as they are repeatedly charged and discharged, causing internal pressure to rise. If this pressure builds up, there's a risk of explosion. Therefore, secondary batteries have a gas-venting mechanism. In this regard, consider Figure 1.

[0005] Fig. 1 is a drawing showing a venting structure of a secondary battery according to the prior art. Referring to Fig. 1, a secondary battery (1) may include an electrode assembly (2), a case (3) that accommodates the electrode assembly (2), and a cap assembly (4) that covers the upper side of the case (3).

[0006] The cap assembly (4) may include a cap plate (5), a venting member (7), and a current interrupt device (8, Current Interrupt Device, CID). The cap plate (5) may include an exhaust port (6). A plurality of exhaust ports (6) may be formed along the outer circumference of the protruding cylindrical head of the cap plate (5). The cap plate (5) may be electrically connected by being coupled to the venting member (7). The current interrupt device (8) may be electrically connected to the electrode assembly (2) and the cap plate (5) by being coupled to the electrode lead of the electrode assembly (2) and the venting member (7) (Fig. 1a).

[0007] When the internal pressure of the case (3) increases, the vent member (7) may be deformed, causing a portion of the current cutoff device (8) to be separated. As a result, the electrode assembly (2) and the cap plate (5) may be insulated (Fig. 1 b). In addition, the vent member (7) may be broken, allowing gas and heat inside the case (3) to be discharged to the outside through the exhaust port (6) (Fig. 1 c). The vent member (7) may include a notch portion formed with a notch to facilitate breaking.

[0008] In the conventional venting structure, the notch portion of the vent member (7) is formed asymmetrically, so that the vent member (7) can be open only on one side and closed on the other side (c in Fig. 1). Therefore, since gas and heat are discharged only on one side, they cannot be discharged quickly, which poses a risk of explosion or ignition. In addition, since the size of the exhaust port (6) on one side must be large in order to discharge the gas and heat quickly, there is a problem that the battery capacity is relatively reduced. In addition, since the vent member (7) is open only on one side, the size of the broken piece when the notch portion is broken may be large, which may hinder the discharge of gas and heat.

[0009] A related prior art document is Korean Patent Publication No. 10-2011-0095118.

[0010] The present invention has been devised to solve the above-described problems, and aims to provide a secondary battery in which gas or heat generated internally is discharged quickly and evenly, thereby improving safety.

[0011] The purpose of the present invention is to provide a secondary battery with increased battery capacity or reduced size.

[0012] The purpose of the present invention is to provide a secondary battery in which the notch portion of the vent member is sufficiently and reliably broken.

[0013] The purpose of the present invention is to provide a secondary battery in which a vent member and a current blocking device are stably coupled.

[0014] The purpose of the present invention is to provide a secondary battery in which a broken piece formed by breaking a notch portion of a vent member is stably supported.

[0015] The technical objectives of the present invention are not limited to the purposes mentioned above. Other objectives and advantages of the present invention not mentioned above can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the objectives and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0016] In order to solve the above-described problem, the present invention provides a secondary battery including an electrode assembly (100), a case (200), and a cap assembly (300).

[0017] The above case (200) accommodates the electrode assembly (100) and can be opened to one side in the first direction.

[0018] The above cap assembly (300) can cover one end of the first direction of the case (200).

[0019] The above cap assembly (300) may include a cap plate (310) and a vent member (320).

[0020] The above cap plate (310) may include an exhaust port (312).

[0021] The above vent member (320) can be placed on the other side of the first direction of the cap plate (310).

[0022] The above vent member (320) may have a plurality of notch portions (N).

[0023] A notch can be formed in each of the plurality of notch portions (N).

[0024] If the internal pressure of the above case (200) exceeds the first threshold value, the plurality of notch portions (N) may be broken.

[0025] The above vent member (320) may be plate-shaped.

[0026] The above plurality of notches (N) can be positioned along the circumferential direction surrounding the first portion (322) of the vent member (320).

[0027] The above plurality of notches (N) can be positioned at a predetermined interval from each other.

[0028] Each of the above notch portions (N) may include a pair of side portions (N1) and an outer portion (N2).

[0029] The above pair of side portions (N1) can be formed to extend outward from the first portion (322).

[0030] The above pair of side portions (N1) can be spaced apart from each other.

[0031] The above outer portion (N2) can connect the outer ends of the pair of side portions (N1).

[0032] The above outer portion (N2) may partially surround the first portion (322).

[0033] Each of the above notch portions (N) may have a predetermined radial section (S) in which the distance between the pair of side portions (N1) gradually increases as the distance increases in the radial direction from the center (C) of the first portion (322).

[0034] In one embodiment, the outer portion (N2) of each of the notch portions (N) may protrude convexly toward the outside of the first portion (322).

[0035] In one embodiment, the plurality of notches (N) may have corresponding sizes and shapes and be positioned at equiangular intervals around the first portion (322).

[0036] In one embodiment, each of the notches (N) may have a fan shape centered on the first portion (322).

[0037] In one embodiment, the plurality of notches (N) may have corresponding sizes and shapes.

[0038] The above plurality may be 3 or more and 6 or less.

[0039] In one embodiment, the plurality of notches (N) may have corresponding sizes and shapes and be positioned at equiangular intervals around the first portion (322).

[0040] The above vent member (320) may include the first portion (322), the second portion (324), and a plurality of third portions (326).

[0041] The above second portion (324) can surround the above first portion (322) and the plurality of notch portions (N).

[0042] The above plurality of third portions (326) can be located between the plurality of notch portions (N).

[0043] The above plurality of third sections (326) can extend in one or the other direction in the radial direction.

[0044] The above plurality of third parts (326) can connect the first part (322) and the second part (324).

[0045] The width (W) of each of the third portions (326) may be greater than or equal to 1 / 25 and less than or equal to 1 / 4 of the diameter of the case (200) or cap assembly (300).

[0046] In one embodiment, the width (W) of each of the third portions (326) may be greater than or equal to 1 / 25 and less than or equal to 3 / 20 of the diameter of the case (200) or cap assembly (300).

[0047] In one embodiment, the vent member (320) may be formed so that the central portion protrudes toward the other side in the first direction.

[0048] Accordingly, the other end of the first portion (322) in the first direction may be located on the other side in the first direction than the other end of the outer portion (N2) in the first direction of each of the plurality of notch portions (N).

[0049] When the internal pressure of the case (200) is equal to or greater than the second threshold value, the vent member (320) can be bent so that the central portion protrudes to one side in the first direction.

[0050] Accordingly, one end of the first portion (322) in the first direction may be located on one side of the first direction compared to one end of the outer portion (N2) in the first direction of each of the plurality of notch portions (N) when the plurality of notch portions (N) are not broken.

[0051] In one embodiment, the second threshold may be different from the first threshold.

[0052] In one embodiment, the second threshold may be greater than or equal to the first threshold.

[0053] In one embodiment, for each of the notch portions (N), the strength of the outer portion (N2) may be different from the strength of the pair of side portions (N1).

[0054] In one embodiment, in each of the notch portions (N), the strength of the outer portion (N2) may be less than the strength of the pair of side portions (N1).

[0055] In one embodiment, the diameter (R) of the first portion (322) may be greater than or equal to 1 / 25 and less than or equal to 1 / 4 of the diameter of the case (200) or cap assembly (300).

[0056] In one embodiment, the diameter (R) of the first portion (322) may be greater than or equal to 3 / 40 and less than or equal to 1 / 8 of the diameter of the case (200) or cap assembly (300).

[0057] In one embodiment, the vent member (320) may be coupled and electrically connected to the cap plate (310).

[0058] The above cap assembly (300) may further include a current blocking device (340) that electrically connects the electrode assembly (100) and the cap plate (310) by being coupled with the first portion (322).

[0059] According to embodiments of the present invention, a secondary battery may include: an electrode assembly (100); a case (200) that accommodates the electrode assembly (100) and is open to one side in a first direction; and a cap assembly (300) that covers one end of the case (200) in the first direction. The cap assembly (300) may include a cap plate (310) that includes an exhaust port (312), and a plate-shaped vent member (320) that is arranged on the other side of the cap plate (310) in the first direction and has a plurality of notch portions (N) each having a notch formed therein, and in which the plurality of notch portions (N) can be broken when the internal pressure of the case (200) becomes equal to or higher than a first threshold value. The plurality of notch portions (N) may be positioned along the circumferential direction surrounding the first portion (322) of the vent member (320) and may be positioned spaced apart from each other by a predetermined distance. Each of the notch portions (N) may include a pair of side portions (N1) that extend outward from the first portion (322) and are spaced apart from each other, and an outer portion (N2) that connects the outer ends of the pair of side portions (N1) and partially surrounds the first portion (322). Each of the notch portions (N) may have a predetermined radial section (S) in which the distance between the pair of side portions (N1) gradually increases as it gets farther away from the center (C) of the first portion (322) in the radial direction.

[0060] Accordingly, when the internal pressure of the secondary battery (10) increases, the plurality of notched portions (N) surrounding the first portion (322) of the vent member (320) may be broken, and not only the outer portion (N2) of each notched portion (N) but also a pair of side portions (N1) may be broken, so that gas or heat generated inside the secondary battery (10) can be quickly discharged in all directions. For example, when projected onto a plane perpendicular to the first direction, gas or heat can be quickly discharged in a radial direction from the first portion (322). Accordingly, the risk of ignition or explosion of the secondary battery (10) is reduced, so that the safety of the secondary battery (10) can be improved.

[0061] In addition, since the exhaust port (312) of the cap plate (310) can be formed to be distributed in all directions so that gas or heat passing through the broken vent member (320) can be quickly discharged in all directions, the size (e.g., width / diameter or height) of the cap plate (310) can be reduced. If the width / diameter of the cap plate (310) is reduced, a short circuit between the cap plate (310) and the case (200) can be prevented, so that the safety of the secondary battery (10) can be improved. If the height (width / length in the first direction) of the cap plate (310) is reduced, the width / length in the first direction of the electrode assembly (100) can be increased, so that the actual capacity can be increased or the secondary battery can be miniaturized.

[0062] In addition, since not only the outer portion (N2) of each notch portion (N) but also a pair of side portions (N1) can be broken, even if the size of each notch portion (N) is reduced, gas or heat can be discharged more quickly than when only the outer portion (N2) of each notch portion (N) is broken. If the size of each notch portion (N) is reduced, the size of each broken piece (L) formed when each notch portion (N) is broken can also be reduced. Accordingly, the size of the empty space provided between the cap plate (310) and the vent member (320) can be reduced so that a plurality of broken pieces (L) can be bent to form an opening (H) in the vent member (320). Accordingly, since the size (e.g., width / diameter or height) of the cap plate (310) can be reduced, the safety of the secondary battery (10) can be improved, the battery capacity can be increased, or the secondary battery (10) can be miniaturized.

[0063] In addition, since each notch portion (N) has the predetermined section (S), even if a plurality of notches (N) are positioned along the circumferential direction, the overall size of a plurality of openings (H) formed by breaking a plurality of notches (N) can increase. Accordingly, gas or heat can be quickly discharged.

[0064] According to embodiments of the present invention, the outer portion (N2) of each of the notch portions (N) may protrude convexly toward the outside of the first portion (322).

[0065] Accordingly, the inner area (area of ​​the fracture fragment (L)) of each notch portion (N) can be increased. Accordingly, each notch portion (N) can receive sufficient pressure, so that each notch portion (N) can be sufficiently fractured. Accordingly, the risk of ignition or explosion of the secondary battery (10) is reduced, so that the safety of the secondary battery (10) can be improved.

[0066] According to embodiments of the present invention, the plurality of notches (N) may have sizes and shapes corresponding to each other and be positioned at equal angular intervals around the first portion (322).

[0067] Accordingly, when the multiple notches (N) of the vent member (320) are broken, gas or heat can be discharged uniformly and quickly in all directions. Accordingly, the risk of ignition or explosion of the secondary battery (10) is reduced, so the safety of the secondary battery (10) can be improved.

[0068] According to embodiments of the present invention, each of the notch portions (N) may have a fan shape centered on the first portion (322).

[0069] Accordingly, the overall size of the plurality of openings (H) formed by the rupture of the plurality of notches (N) can be increased. Accordingly, gas or heat can be quickly discharged.

[0070] Additionally, when multiple notches (N) are broken, gas or heat can be discharged uniformly and quickly in all directions. Accordingly, the risk of ignition or explosion of the secondary battery (10) is reduced, thereby improving the safety of the secondary battery (10).

[0071] According to embodiments of the present invention, the plurality of notches (N) may have sizes and shapes corresponding to each other. The number of notches may be three or more and six or less.

[0072] Accordingly, since there are six or fewer simple notches (N), the inner area of ​​each notch (N) (area of ​​the fracture piece (L)) can be sufficiently large. Accordingly, since each notch (N) can receive sufficient pressure, each notch (N) can be sufficiently fractured.

[0073] In addition, since there are three or more notch portions (N), the angle between a pair of side portions (N1) of each notch portion (N) can be sufficiently reduced to a predetermined angle (e.g., 120 degrees) or less. Accordingly, since the length of the outer portion (N2) is reduced, not only the outer portion (N2) but also the pair of side portions (N1) can receive sufficient pressure, both the outer portion (N2) and the pair of side portions (N1) can be sufficiently fractured.

[0074] According to embodiments of the present invention, the plurality of notch portions (N) may have corresponding sizes and shapes and may be positioned at equiangular intervals centered on the first portion (322). The vent member (320) may include the first portion (322), a second portion (324) surrounding the first portion (322) and the plurality of notch portions (N), and a plurality of third portions (326) positioned between the plurality of notch portions (N) and extending in one or the other direction in the radial direction to connect the first portion (322) and the second portion (324). The width (W) of each of the third portions (326) may be greater than or equal to 1 / 25 and less than or equal to 1 / 4 of the diameter of the case (200) or the cap assembly (300).

[0075] Accordingly, since the width (W) of the third portion (326) is 1 / 25 or more of the diameter of the case (200) or the cap assembly (300), the width of the third portion (326) is sufficiently large so that the third portion (326) can stably support the first portion (322) that supports the plurality of broken pieces (L). Accordingly, the plurality of broken pieces (L) can be stably supported. In addition, since the width (W) of the third portion (326) is 1 / 4 or less of the diameter of the case (200) or the cap assembly (300), the size of the opening (H) formed by the fracture of the plurality of notches (N) can be sufficiently large. Accordingly, gas or heat can be quickly discharged.

[0076] According to embodiments of the present invention, the width (W) of each of the third portions (326) may be greater than or equal to 1 / 25 and less than or equal to 3 / 20 of the diameter of the case (200) or the cap assembly (300).

[0077] Accordingly, since the width (W) of the third portion (326) is 1 / 25 or more of the diameter of the case (200) or the cap assembly (300), the width of the third portion (326) is sufficiently large so that the third portion (326) can stably support the first portion (322) that supports the plurality of broken pieces (L). Accordingly, the plurality of broken pieces (L) can be stably supported. In addition, since the width (W) of the third portion (326) is 3 / 20 or less of the diameter of the case (200) or the cap assembly (300), the size of the opening (H) formed by the fracture of the plurality of notches (N) can be sufficiently large. Accordingly, gas or heat can be quickly discharged.

[0078] According to embodiments of the present invention, the vent member (320) is formed so that its central portion protrudes to the other side in the first direction, and thus, the other end of the first portion (322) in the first direction can be located on the other side in the first direction than the other end of the outer portion (N2) of each of the plurality of notch portions (N) in the first direction. When the internal pressure of the case (200) is equal to or greater than the second threshold value, the vent member (320) is bent so that its central portion protrudes to one side in the first direction, and thus, one end of the first portion (322) in the first direction can be located on one side in the first direction than one end of the outer portion (N2) of each of the plurality of notch portions (N) in the first direction when the plurality of notch portions (N) are not broken.

[0079] Accordingly, when the vent member (320) is deformed (flipped) so that the central portion of the vent member (320) protrudes from the other side in the first direction to one side, a force such as a compressive force or a tensile force can be concentrated and acted on a plurality of notch portions (N) having relatively small strength among the vent member (320) (for example, toward one side or the other side in the radial direction). Accordingly, when the vent member (320) is deformed (flipped), the plurality of notch portions (N) can be sufficiently broken. Accordingly, gas or heat can be quickly discharged.

[0080] In particular, when the vent member (320) is deformed (turned over) and a compressive or tensile force is applied to one or the other side in the radial direction to the vent member (320), the degree to which the side portion (N1) with low rigidity is deformed due to the formation of a notch may be different from the degree to which the two sides of the side portion (N1) with high rigidity are deformed due to the non-formation of the notch. Due to this difference in the degree of deformation, the side portion (N1) is greatly pressurized along the longitudinal direction of the side portion (N1) extending to one or the other side in the radial direction, so that the side portion (N1) can be sufficiently fractured. Accordingly, gas or heat can be quickly discharged.

[0081] According to embodiments of the present invention, the second threshold value may be different from the first threshold value.

[0082] Accordingly, since bending (flip) and breaking of the bent member (320) can occur sequentially, multiple notch portions (N) can be broken reliably.

[0083] According to embodiments of the present invention, the second threshold value may be greater than or equal to the first threshold value.

[0084] Accordingly, when the second threshold value is greater than the first threshold value, when the internal pressure of the case (200) reaches the first threshold value and the multiple notch portions (N) are fractured but insufficiently fractured by the internal pressure, when the internal pressure increases due to the insufficient fracture and reaches the second threshold value, the vent member (320) is deformed (flipped) and the multiple notch portions (N) are pressurized and can be sufficiently fractured. In addition, when the second threshold value is equal to the first threshold value, when the internal pressure of the case (200) reaches the first threshold value, the multiple notch portions (N) can be sufficiently fractured by the internal pressure and the deformation of the vent member (320). Therefore, it is possible to prevent the multiple notch portions (N) from being insufficiently fractured. Accordingly, the risk of ignition or explosion of the secondary battery (10) is reduced, so the safety of the secondary battery (10) can be improved.

[0085] According to embodiments of the present invention, in each of the notch portions (N), the strength of the outer portion (N2) may be different from the strength of the pair of side portions (N1).

[0086] Accordingly, since the outer portion (N2) and the side portion (N1) can be broken sequentially, multiple notch portions (N) can be broken reliably.

[0087] According to embodiments of the present invention, in each of the notch portions (N), the strength of the outer portion (N2) may be less than the strength of the pair of side portions (N1).

[0088] Accordingly, the outer portion (N2) can be fractured before the pair of side portions (N1). Accordingly, the fracture of the pair of side portions (N1) connected to both ends of the outer portion (N2) can be induced by the outer portion (N2) that is fractured first. Accordingly, not only the outer portion (N2) of each notch portion (N) but also the pair of side portions (N1) can be sufficiently fractured.

[0089] According to embodiments of the present invention, the diameter (R) of the first portion (322) may be greater than or equal to 1 / 25 and less than or equal to 1 / 4 of the diameter of the case (200) or the cap assembly (300).

[0090] Accordingly, since the diameter (R) of the first portion (322) is 1 / 25 or more of the diameter of the case (200) or the cap assembly (300), the size of the first portion (322) is sufficiently large to stably support a plurality of broken pieces (L), and when the first portion (322) is combined with the current interrupting device (340), the first portion (322) and the current interrupting device (340) can be stably joined (e.g., welded). In addition, since the diameter (R) of the first portion (322) is 1 / 4 or less of the diameter of the case (200) or the cap assembly (300), the size of the opening (H) formed by the breaking of the plurality of notches (N) can be sufficiently large. Accordingly, gas or heat can be quickly discharged.

[0091] According to embodiments of the present invention, the diameter (R) of the first portion (322) may be greater than or equal to 3 / 40 and less than or equal to 1 / 8 of the diameter of the case (200) or the cap assembly (300).

[0092] Accordingly, since the diameter (R) of the first portion (322) is 3 / 40 or more of the diameter of the case (200) or the cap assembly (300), the size of the first portion (322) is sufficiently large to stably support a plurality of broken pieces (L), and when the first portion (322) is combined with the current interrupting device (340), the first portion (322) and the current interrupting device (340) can be stably joined (e.g., welded). In addition, since the diameter (R) of the first portion (322) is 1 / 8 or less of the diameter of the case (200) or the cap assembly (300), the size of the opening (H) formed by the breaking of the plurality of notches (N) can be sufficiently large. Accordingly, gas or heat can be quickly discharged.

[0093] According to embodiments of the present invention, the vent member (320) may be coupled and electrically connected to the cap plate (310). The cap assembly (300) may further include a current blocking device (340) that electrically connects the electrode assembly (100) and the cap plate (310) by being coupled to the first portion (322).

[0094] Accordingly, since the current cutoff device (340) is coupled to the first portion (322) where the notch portion (N) is not formed, the vent member (320) and the current cutoff device (340) can be stably coupled. In addition, when the notch portion (N) is broken, the first portion (322) can stably support the broken piece (L).

[0095] In addition to the effects described above, specific effects of the present invention are described below while explaining specific details for carrying out the invention.

[0096] Figure 1 is a drawing showing the venting structure of a secondary battery according to the prior art.

[0097] FIG. 2 and FIG. 3 are cross-sectional views schematically showing a secondary battery according to one embodiment of the present invention.

[0098] Figures 4 to 6 are plan views showing three embodiments of the vent member of Figures 2 and 3.

[0099] Fig. 7 is a perspective view schematically showing the vent member of Fig. 4 in an open state.

[0100] [Explanation of symbols]

[0101] 10: Secondary batteries

[0102] 100: Electrode assembly 110: Electrode lead

[0103] 200: Case

[0104] 300: Cap assembly

[0105] 310: Cap plate 312: Exhaust port

[0106] 320: Venting member 322: First section

[0107] 324: Second part 326: Third part

[0108] N: Notch N1: Side

[0109] N2: Outer part S: Specified section

[0110] L: Fractured piece H: Opening

[0111] 330: Gasket

[0112] 340: Current circuit breaker

[0113] 342: First joint 344: Second joint

[0114] The above-described objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily practice the technical idea of ​​the present invention. In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0115] 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.

[0116] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0117] Hereinafter, the phrase "any configuration is placed on (or below)" a component or "on (or below)" a component may mean that any configuration is placed in contact with the upper surface (or lower surface) of said component, and that other configurations may be interposed between said component and any configuration placed on (or below) said component.

[0118] 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 one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through another component.

[0119] As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "consisting of" or "comprising" should not necessarily be construed to include all of the components or steps described in the specification, and should be construed to mean that some of the components or steps may not be included, or that additional components or steps may be included.

[0120]

[0121] Fig. 1 is a drawing showing a venting structure of a secondary battery according to the prior art. Figs. 2 and 3 are cross-sectional views schematically showing a secondary battery according to an embodiment of the present invention. Figs. 4 to 6 are plan views showing three embodiments of the vent member of Figs. 2 and 3. Fig. 7 is a perspective view schematically showing the vent member of Fig. 4 in an open state.

[0122]

[0123] [Secondary battery]

[0124] Referring to FIGS. 2 and 3, a secondary battery (10) according to one embodiment may include an electrode assembly (100), a case (200), and a cap assembly (300).

[0125] The electrode assembly (100) may be a jelly roll-shaped structure in which a positive electrode sheet, a separator sheet, and a negative electrode sheet are laminated and wound. However, the configuration is not limited to this. The electrode assembly (100) may include an electrode lead (110) that protrudes toward one side (e.g., upward) in a first direction (e.g., upward-downward).

[0126] The case (200) can accommodate the electrode assembly (100). The case (200) can be opened on one side in the first direction.

[0127] The cap assembly (300) can cover one end of the first direction of the case (200).

[0128] The cap assembly (300) may include a cap plate (310) and a vent member (320). The cap assembly (300) may include a gasket (330). The cap assembly (300) may include a current interrupt device (340, Current Interrupt Device, CID).

[0129] The cap plate (310) may include an exhaust port (312). The exhaust port (312) may be formed on a side or upper surface of the cap plate (310). One or more exhaust ports (312) may be formed along a circumferential direction. Here, the circumferential direction may be a direction extending in a first direction and surrounding an imaginary axis (A) passing through the center of the first portion (322).

[0130] The cap plate (310) can be combined with the vent member (320). The cap plate (310) can be electrically connected to the vent member (320).

[0131] A gasket (330) may be placed between the cap plate (310) and the vent member (320) and the case (200). The gasket (330) may insulate the case (200) from the cap plate (310) and the vent member (320).

[0132] The current blocking device (340) may be arranged on the other side of the first direction of the vent member (320). The current blocking device (340) may electrically connect the electrode assembly (100) and the cap plate (310). To this end, the current blocking device (340) may include a first coupling portion (342) and a second coupling portion (344). The first coupling portion (342) may be coupled with the electrode lead (110) of the electrode assembly (100). The second coupling portion (344) may be coupled with the first portion (322) of the vent member (320) that is electrically connected to the cap plate (310).

[0133] The current cutoff device (340) electrically connects the electrode assembly (100) and the cap plate (310) and when the internal pressure of the case (200) exceeds a predetermined value, the current cutoff device (340) can electrically cut off the electrode assembly (100) and the cap plate (310).

[0134] For example, the current interrupting device (340) may include a first coupling portion (342) and a second coupling portion (344) as described above, and when the internal pressure of the case (200) becomes higher than the second threshold value, the vent member (320) is deformed, and accordingly, the second coupling portion (344) coupled with the vent member (320) may be separated from the first coupling portion (342) as shown in FIG. 1. Accordingly, the electrode assembly (100) and the cap plate (310) may be electrically disconnected.

[0135] Below, the vent member (320) will be examined.

[0136]

[0137] [Bent absence]

[0138] The vent member (320) may be placed on the other side (e.g., the lower side) of the cap plate (310) in the first direction. The vent member (320) may be plate-shaped. The vent member (320) may be formed of a material including metal (e.g., aluminum).

[0139]

[0140] [Notch]

[0141] Referring further to FIGS. 4 to 7, the vent member (320) according to one embodiment may have a plurality of notch portions (N).

[0142] A plurality of notches (N) may be positioned along the aforementioned circumferential direction surrounding the first portion (322) of the vent member (320).

[0143] A plurality of notches (N) may be positioned at a predetermined interval from each other. When the internal pressure of the case (200) exceeds the first threshold value, the plurality of notches (N) may be broken.

[0144] Each notch portion (N) may have a notch formed therein. The notches may be formed continuously or intermittently. When each notch portion (N) is broken, a broken piece (L) may be formed. One side of the broken piece (L) may be joined to the first portion (322). When the broken piece (L) is bent or deformed, an opening (H) may be formed in the vent member (300) (Fig. 7). Gas and heat may be discharged to the outside through the opening (H) and the exhaust port (312).

[0145] Each notch portion (N) may include a pair of side portions (N1) and an outer portion (N2).

[0146] A pair of side portions (N1) may be formed by extending outwardly (e.g., radially to one side or the other side) from the first portion (322). The pair of side portions (N1) may be spaced apart from each other.

[0147] Here, the radial direction may be a direction extending in the first direction and moving away from or closer to the imaginary axis on a plane perpendicular to the imaginary axis passing through the center (C) of the first portion (322).

[0148] The outer portion (N2) can connect the outer ends of a pair of side portions (N1). The outer portion (N2) can partially surround the first portion (322).

[0149] Accordingly, when the internal pressure of the secondary battery (10) increases, the plurality of notched portions (N) surrounding the first portion (322) of the vent member (320) may be broken, and not only the outer portion (N2) of each notched portion (N) but also a pair of side portions (N1) may be broken, so that gas or heat generated inside the secondary battery (10) can be quickly discharged in all directions. For example, when projected onto a plane perpendicular to the first direction, gas or heat can be quickly discharged in a radial direction from the first portion (322). Accordingly, the risk of ignition or explosion of the secondary battery (10) is reduced, so that the safety of the secondary battery (10) can be improved.

[0150] In addition, since the exhaust port (312) of the cap plate (310) can be formed to be distributed in all directions so that gas or heat passing through the broken vent member (320) can be quickly discharged in all directions, the size (e.g., width / diameter or height) of the cap plate (310) can be reduced. If the width / diameter of the cap plate (310) is reduced, a short circuit between the cap plate (310) and the case (200) can be prevented, so that the safety of the secondary battery (10) can be improved. If the height (width / length in the first direction) of the cap plate (310) is reduced, the width / length in the first direction of the electrode assembly (100) can be increased, so that the actual capacity can be increased or the secondary battery can be miniaturized.

[0151] In addition, since not only the outer portion (N2) of each notch portion (N) but also a pair of side portions (N1) can be broken, even if the size of each notch portion (N) is reduced, gas or heat can be discharged more quickly than when only the outer portion (N2) of each notch portion (N) is broken. If the size of each notch portion (N) is reduced, the size of each broken piece (L) formed when each notch portion (N) is broken can also be reduced. Accordingly, the size of the empty space provided between the cap plate (310) and the vent member (320) can be reduced so that a plurality of broken pieces (L) can be bent to form an opening (H) in the vent member (320). Accordingly, since the size (e.g., width / diameter or height) of the cap plate (310) can be reduced, the safety of the secondary battery (10) can be improved, the battery capacity can be increased, or the secondary battery (10) can be miniaturized.

[0152] The outer portion (N2) of each notch portion (N) may protrude convexly toward the outside of the first portion (322).

[0153] Accordingly, the inner area (area of ​​the fracture fragment (L)) of each notch portion (N) can be increased. Accordingly, each notch portion (N) can receive sufficient pressure, so that each notch portion (N) can be sufficiently fractured. Accordingly, the risk of ignition or explosion of the secondary battery (10) is reduced, so that the safety of the secondary battery (10) can be improved.

[0154] Each notch portion (N) may have a predetermined radial section (S) in which the distance between a pair of side portions (N1) gradually increases as it moves away from the center (C) of the first portion (322) in the radial direction (Fig. 4).

[0155] Accordingly, since each notch portion (N) has the predetermined section (S), even if a plurality of notches (N) are positioned along the circumferential direction, the overall size of a plurality of openings (H) formed by breaking a plurality of notches (N) can increase. Accordingly, gas or heat can be quickly discharged.

[0156] For each notch portion (N), the strength of the outer portion (N2) may be different from the strength of a pair of side portions (N1).

[0157] Accordingly, since the outer portion (N2) and the side portion (N1) can be broken sequentially, multiple notch portions (N) can be broken reliably.

[0158] For each notch portion (N), the strength of the outer portion (N2) may be less than the strength of a pair of side portions (N1).

[0159] Accordingly, the outer portion (N2) can be fractured before the pair of side portions (N1). Accordingly, the fracture of the pair of side portions (N1) connected to both ends of the outer portion (N2) can be induced by the outer portion (N2) that is fractured first. Accordingly, not only the outer portion (N2) of each notch portion (N) but also the pair of side portions (N1) can be sufficiently fractured.

[0160] Each notch (N) may have a fan shape centered on the first portion (322).

[0161] Accordingly, the overall size of the plurality of openings (H) formed by the rupture of the plurality of notches (N) can be increased. Accordingly, gas or heat can be quickly discharged.

[0162] Additionally, when multiple notches (N) are broken, gas or heat can be discharged uniformly and quickly in all directions. Accordingly, the risk of ignition or explosion of the secondary battery (10) is reduced, thereby improving the safety of the secondary battery (10).

[0163] The plurality of notches (N) may have corresponding sizes and shapes. The plurality may be three or more and six or less.

[0164] Accordingly, since the number of notches (N) is 6 or less, the inner area of ​​each notch (N) (area of ​​the fracture piece (L)) can be sufficiently large. Accordingly, since each notch (N) can receive sufficient pressure, each notch (N) can be sufficiently fractured.

[0165] In addition, since there are three or more notch portions (N), the angle between a pair of side portions (N1) of each notch portion (N) can be sufficiently reduced to a predetermined angle (e.g., 120 degrees) or less. Accordingly, since the length of the outer portion (N2) is reduced, not only the outer portion (N2) but also the pair of side portions (N1) can receive sufficient pressure, both the outer portion (N2) and the pair of side portions (N1) can be sufficiently fractured.

[0166] The plurality of notches (N) may have corresponding sizes and shapes and may be positioned at equiangular intervals centered on the first portion (322).

[0167] Accordingly, when the multiple notches (N) of the vent member (320) are broken, gas or heat can be discharged uniformly and quickly in all directions. Accordingly, the risk of ignition or explosion of the secondary battery (10) is reduced, so the safety of the secondary battery (10) can be improved.

[0168]

[0169] [Part 1, Part 2, Part 3]

[0170] The vent member (320) may include a first portion (322). The vent member (320) may include a second portion (324) and a third portion (326).

[0171] The first portion (322) may be the central portion of the vent member (320). One side of a plurality of broken pieces (L) may be joined to the first portion (322) (Fig. 7).

[0172] The diameter (R) of the first portion (322) may be greater than or equal to 1 / 25 and less than or equal to 1 / 4 of the diameter of the case (200) or the cap assembly (300). For example, the diameter (R) of the first portion (322) may be greater than or equal to 1 mm and less than or equal to 5 mm. For example, when the diameter of the case (200) or the cap assembly (300) is 21 mm, the diameter (R) of the first portion (322) may be greater than or equal to 1 mm and less than or equal to 5 mm.

[0173] Accordingly, since the diameter (R) of the first portion (322) is 1 / 25 or more of the diameter of the case (200) or the cap assembly (300), the size of the first portion (322) is sufficiently large to stably support a plurality of broken pieces (L), and when the first portion (322) is combined with the current interrupting device (340), the first portion (322) and the current interrupting device (340) can be stably joined (e.g., welded). In addition, since the diameter (R) of the first portion (322) is 1 / 4 or less of the diameter of the case (200) or the cap assembly (300), the size of the opening (H) formed by the breaking of the plurality of notches (N) can be sufficiently large. Accordingly, gas or heat can be quickly discharged.

[0174] Preferably, the diameter (R) of the first portion (322) may be greater than or equal to 3 / 40 and less than or equal to 1 / 8 of the diameter of the case (200) or the cap assembly (300). For example, the diameter (R) of the first portion (322) may be greater than or equal to 1.5 mm and less than or equal to 2.5 mm. For example, when the diameter of the case (200) or the cap assembly (300) is 21 mm, the diameter (R) of the first portion (322) may be greater than or equal to 1.5 mm and less than or equal to 2.5 mm.

[0175] Accordingly, since the diameter (R) of the first portion (322) is 3 / 40 or more of the diameter of the case (200) or the cap assembly (300), the size of the first portion (322) is sufficiently large to stably support a plurality of broken pieces (L), and when the first portion (322) is combined with the current interrupting device (340), the first portion (322) and the current interrupting device (340) can be stably joined (e.g., welded). In addition, since the diameter (R) of the first portion (322) is 1 / 8 or less of the diameter of the case (200) or the cap assembly (300), the size of the opening (H) formed by the breaking of the plurality of notches (N) can be sufficiently large. Accordingly, gas or heat can be quickly discharged.

[0176] The first portion (322) can be coupled to the aforementioned current blocking device (340). Accordingly, the current blocking device (340) can electrically connect the electrode assembly (100) and the cap plate (310) through the first portion (322).

[0177] Accordingly, since the current cutoff device (340) is coupled to the first portion (322) where the notch portion (N) is not formed, the vent member (320) and the current cutoff device (340) can be stably coupled. In addition, when the notch portion (N) is broken, the first portion (322) can stably support the broken piece (L).

[0178] The second portion (324) can surround the first portion (322) and a plurality of notches (N).

[0179] A plurality of third sections (326) may be provided. The plurality of third sections (326) may be positioned between the plurality of notch portions (N). The plurality of third sections (326) may extend in one or the other radial direction. The plurality of third sections (326) may connect the first section (322) and the second section (324).

[0180] When a plurality of notches (N) have corresponding sizes and shapes and are positioned at equiangular intervals with the first portion (322) as the center, the width (W) of each third portion (326) may be greater than or equal to 1 / 25 and less than or equal to 1 / 4 of the diameter of the case (200) or the cap assembly (300). For example, the width (W) of each third portion (326) may be 1 mm or more and 5 mm or less. For example, when the diameter of the case (200) or the cap assembly (300) is 21 mm, the diameter (R) of the first portion (322) may be 1 mm or more and 5 mm or less.

[0181] Accordingly, since the width (W) of the third portion (326) is 1 / 25 or more of the diameter of the case (200) or the cap assembly (300), the width of the third portion (326) is sufficiently large so that the third portion (326) can stably support the first portion (322) that supports the plurality of broken pieces (L). Accordingly, the plurality of broken pieces (L) can be stably supported. In addition, since the width (W) of the third portion (326) is 1 / 4 or less of the diameter of the case (200) or the cap assembly (300), the size of the opening (H) formed by the fracture of the plurality of notches (N) can be sufficiently large. Accordingly, gas or heat can be quickly discharged.

[0182] At this time, preferably, the width (W) of each third portion (326) may be greater than or equal to 1 / 25 and less than or equal to 3 / 20 of the diameter of the case (200) or the cap assembly (300). For example, the diameter (R) of the first portion (322) may be greater than or equal to 1 mm and less than or equal to 3 mm. For example, when the diameter of the case (200) or the cap assembly (300) is 21 mm, the diameter (R) of the first portion (322) may be greater than or equal to 1 mm and less than or equal to 3 mm.

[0183] Accordingly, since the width (W) of the third portion (326) is 1 / 25 or more of the diameter of the case (200) or the cap assembly (300), the width of the third portion (326) is sufficiently large so that the third portion (326) can stably support the first portion (322) that supports the plurality of broken pieces (L). Accordingly, the plurality of broken pieces (L) can be stably supported. In addition, since the width (W) of the third portion (326) is 3 / 20 or less of the diameter of the case (200) or the cap assembly (300), the size of the opening (H) formed by the fracture of the plurality of notches (N) can be sufficiently large. Accordingly, gas or heat can be quickly discharged.

[0184]

[0185] [Deformation of the vent member]

[0186] The vent member (320) may be formed so that its central portion protrudes toward the other side (e.g., the lower side) in the first direction. Accordingly, the other end (e.g., the lower side) in the first direction of the first portion (322) may be located toward the other side in the first direction than the other end (e.g., the lower side) of the outer portion (N2) of each of the plurality of notch portions (N) in the first direction (Fig. 2).

[0187] When the internal pressure of the case (200) becomes equal to or greater than the second threshold value, the vent member (320) may be bent so that the central portion protrudes to one side (e.g., the upper side) in the first direction. Accordingly, one end (e.g., the upper end) of the first portion (322) in the first direction may be located further to one side in the first direction than one end (e.g., the upper end) of each of the outer portions (N2) of the plurality of notch portions (N) in the first direction when the plurality of notch portions (N) are not broken (dotted line in FIG. 3). Here, when the plurality of notch portions (N) are not broken, it may mean that each notch portion (N) is not broken or is assumed not to be broken.

[0188] Accordingly, when the vent member (320) is deformed (flipped) so that the central portion of the vent member (320) protrudes from the other side in the first direction to one side, a force such as a compressive force or a tensile force can be concentrated and acted on a plurality of notch portions (N) having relatively small strength among the vent member (320) (for example, toward one side or the other side in the radial direction). Accordingly, when the vent member (320) is deformed (flipped), the plurality of notch portions (N) can be sufficiently broken. Accordingly, gas or heat can be quickly discharged.

[0189] In particular, when the vent member (320) is deformed (turned over) and a compressive or tensile force is applied to one or the other side in the radial direction to the vent member (320), the degree to which the side portion (N1) with low rigidity is deformed due to the formation of a notch may be different from the degree to which the two sides of the side portion (N1) with high rigidity are deformed due to the non-formation of the notch. Due to this difference in the degree of deformation, the side portion (N1) is greatly pressurized along the longitudinal direction of the side portion (N1) extending to one or the other side in the radial direction, so that the side portion (N1) can be sufficiently fractured. Accordingly, gas or heat can be quickly discharged.

[0190] The above second threshold value may be different from the above-mentioned first threshold value.

[0191] Accordingly, since bending (flip) and breaking of the bent member (320) can occur sequentially, multiple notch portions (N) can be broken reliably.

[0192] The above second threshold value may be greater than or equal to the above-mentioned first threshold value.

[0193] Accordingly, when the second threshold value is greater than the first threshold value, when the internal pressure of the case (200) reaches the first threshold value and the multiple notch portions (N) are fractured but insufficiently fractured by the internal pressure, when the internal pressure increases due to the insufficient fracture and reaches the second threshold value, the vent member (320) is deformed (flipped) and the multiple notch portions (N) are pressurized and can be sufficiently fractured. In addition, when the second threshold value is equal to the first threshold value, when the internal pressure of the case (200) reaches the first threshold value, the multiple notch portions (N) can be sufficiently fractured by the internal pressure and the deformation of the vent member (320). Therefore, it is possible to prevent the multiple notch portions (N) from being insufficiently fractured. Accordingly, the risk of ignition or explosion of the secondary battery (10) is reduced, so the safety of the secondary battery (10) can be improved.

[0194]

[0195] It should be understood that the above-described embodiments are illustrative in all respects and not restrictive, and the scope of the present invention will be determined by the claims that follow, rather than by the detailed description set forth above. Furthermore, the meaning and scope of the claims that follow, as well as all possible modifications and variations derived from their equivalent concepts, should be construed as encompassing the scope of the present invention.

[0196] Although the present invention has been described with reference to the drawings exemplified above, it is to be understood that the present invention is not limited to the embodiments and drawings disclosed herein, and that various modifications may be made by those skilled in the art within the scope of the technical idea of ​​the present invention. Furthermore, even if the operational effects according to the configuration of the present invention have not been explicitly described while describing the embodiments of the present invention, it is natural that the effects predictable by the corresponding configuration should also be acknowledged.

Claims

1. Electrode assembly (100); A case (200) that accommodates the above electrode assembly (100) and is opened to one side in the first direction; and It includes a cap assembly (300) covering one end of the first direction of the case (200), The above cap assembly (300) includes a cap plate (310) including an exhaust port (312), and a plurality of notch portions (N) arranged on the other side of the first direction of the cap plate (310) and each having a notch formed therein, and a plate-shaped vent member (320) capable of causing the plurality of notch portions (N) to break when the internal pressure of the case (200) exceeds a first threshold value. The above plurality of notches (N) are positioned along the circumferential direction surrounding the first portion (322) of the vent member (320) and are spaced apart from each other by a predetermined distance. Each of the above notches (N) is It includes a pair of side parts (N1) that extend outwardly from the first part (322) and are spaced apart from each other, and an outer part (N2) that connects the outer ends of the pair of side parts (N1) and partially surrounds the first part (322). It has a radial predetermined section (S) in which the distance between the pair of side parts (N1) gradually increases as it moves away from the center (C) of the first part (322) in the radial direction. Secondary battery.

2. In claim 1, A secondary battery, wherein the outer portion (N2) of each of the above notch portions (N) protrudes convexly toward the outside of the first portion (322).

3. In claim 1 or claim 2, A secondary battery in which the above plurality of notches (N) have corresponding sizes and shapes and are positioned at equal angular intervals centered on the first portion (322).

4. In any one of claims 1 to 3, A secondary battery, wherein each of the above notches (N) has a fan shape centered on the first portion (322).

5. In claim 4, The above plurality of notches (N) have corresponding sizes and shapes, A secondary battery, wherein the above plurality is 3 or more and 6 or less.

6. In claim 4, The above plurality of notches (N) have corresponding sizes and shapes and are positioned at equal angular intervals centered on the first portion (322). The above-mentioned vent member (320) includes the first portion (322), a second portion (324) surrounding the first portion (322) and the plurality of notched portions (N), and a plurality of third portions (326) positioned between the plurality of notched portions (N) and extending to one or the other side in the radial direction and connecting the first portion (322) and the second portion (324). The width (W) of each of the third portions (326) is greater than or equal to 1 / 25 and less than or equal to 1 / 4 of the diameter of the case (200) or cap assembly (300), the secondary battery.

7. In claim 6, The width (W) of each of the third portions (326) is greater than or equal to 1 / 25 and less than or equal to 3 / 20 of the diameter of the case (200) or cap assembly (300), the secondary battery.

8. In any one of claims 1 to 7, The above-mentioned vent member (320) is formed so that the central portion protrudes to the other side in the first direction, and accordingly, the other end of the first portion (322) in the first direction is located on the other side in the first direction than the other end of the outer portion (N2) in the first direction of each of the plurality of notch portions (N). A secondary battery, wherein when the internal pressure of the case (200) becomes equal to or greater than the second threshold value, the vent member (320) is bent so that the central portion protrudes to one side in the first direction, and accordingly, one end of the first portion (322) in the first direction is located further to one side in the first direction than one end of the outer portion (N2) of each of the plurality of notch portions (N) in the first direction when the plurality of notch portions (N) are not broken.

9. In claim 8, The above second threshold value is different from the above first threshold value, a secondary battery.

10. In claim 8, A secondary battery wherein the second threshold value is greater than or equal to the first threshold value.

11. In any one of claims 1 to 10, A secondary battery, wherein in each of the above notch portions (N), the strength of the outer portion (N2) is different from the strength of the pair of side portions (N1).

12. In claim 11, A secondary battery, wherein in each of the above notch portions (N), the strength of the outer portion (N2) is smaller than the strength of the pair of side portions (N1).

13. In any one of claims 1 to 12, A secondary battery in which the diameter (R) of the first portion (322) is greater than or equal to 1 / 25 and less than or equal to 1 / 4 of the diameter of the case (200) or cap assembly (300).

14. In claim 13, A secondary battery in which the diameter (R) of the first portion (322) is greater than or equal to 3 / 40 and less than or equal to 1 / 8 of the diameter of the case (200) or cap assembly (300).

15. In any one of claims 1 to 14, The above vent member (320) is combined with the cap plate (310) and electrically connected, A secondary battery, wherein the cap assembly (300) further includes a current blocking device (340) that electrically connects the electrode assembly (100) and the cap plate (310) by being coupled with the first portion (322).

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