Rechargeable battery

Abstract

The present invention provides a secondary battery capable of efficiently and reliably relieving an increase in internal pressure. A secondary battery according to one aspect of the present invention comprises a case, an electrode assembly inserted into the case, a cap plate coupled to the case, and a vent portion formed in the case or the cap plate, wherein the vent portion may include a first convex portion and a second convex portion protruding and arranged adjacently to each other, and a connecting notch located between the first convex portion and the second convex portion and connected by a curve.

Description

Technology Field

[0001] The present invention relates to a secondary battery capable of charging and discharging. Background Technology

[0002] Recently, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has increased rapidly, and the development of electric vehicles, energy storage batteries, robots, and satellites has accelerated, research on high-performance secondary batteries capable of repeated charging and discharging is actively underway.

[0003] Currently commercialized rechargeable batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium-ion batteries. Among these, lithium-ion batteries are gaining attention for their advantages, such as the ability to freely charge and discharge with almost no memory effect compared to nickel-based batteries, a very low self-discharge rate, and high energy density.

[0004] These lithium secondary batteries primarily use lithium-based oxides and carbon materials as the positive and negative active materials, respectively. Additionally, the lithium secondary battery comprises a positive plate and a negative plate coated with these positive and negative active materials, respectively; an electrode assembly in which the positive and negative plates are arranged with a separator in between; and an outer casing that seals and encloses the electrode assembly together with an electrolyte.

[0005] Meanwhile, lithium secondary batteries can be classified according to the shape of the battery case into can-type secondary batteries, in which the electrode assembly is embedded in a metal can, and pouch-type secondary batteries, in which the electrode assembly is embedded in a pouch of aluminum laminate sheets. Furthermore, can-type secondary batteries can be further classified into cylindrical batteries and prismatic batteries depending on the shape of the metal can.

[0006] In the case of a prismatic battery, a vent portion is provided that opens as internal pressure increases, and the safety of the secondary battery can be increased if the vent portion opens accurately at a preset pressure. The problem to be solved

[0007] The present invention provides a secondary battery capable of efficiently and reliably relieving an increase in internal pressure. means of solving the problem

[0008] A secondary battery according to one aspect of the present invention comprises a case, an electrode assembly inserted into the case, a cap plate coupled to the case, and a vent portion formed in the case or the cap plate, wherein the vent portion may include a first convex portion and a second convex portion protruding and arranged adjacently to each other, and a connecting notch located between the first convex portion and the second convex portion and connected by a curve.

[0009] According to one aspect of the present invention, the angle of inclination formed by the tangent of the first convex portion or the second convex portion with the plane parallel to the cap plate in the portion connected to the connecting notch may be 1 to 20 degrees.

[0010] According to one aspect of the present invention, the connecting notch includes a first curve line and a second curve line, and the first curve line and the second curve line may protrude convexly in opposite directions.

[0011] According to one aspect of the present invention, the vent portion may further include a plurality of side notches connected to the connecting notch.

[0012] According to one aspect of the present invention, the first tangent angle formed by the tangent at the end adjacent to the connecting notch in the first convex portion with a virtual reference plane parallel to the cap plate may be formed to be smaller than the second tangent angle formed by the tangent at the end adjacent to any one of the side notches in the first convex portion with the reference plane.

[0013] According to one aspect of the present invention, the second tangent angle may be 1.1 to 3.5 times the first tangent angle.

[0014] According to one aspect of the present invention, the connecting notch includes an inflection point where the first curve line and the second curve line meet, a first reference point where the first curve line forms a maximum distance from a reference line extending in the longitudinal direction from the center of the width direction of the vent portion, and a second reference point where the second curve line forms a maximum distance from the reference line. The first angle of inclination formed by the tangent of the outer end of the first convex portion at the first reference point with a virtual reference plane parallel to the cap plate and the second angle of inclination formed by the tangent of the outer end of the first convex portion at the second reference point with the reference plane may be formed to be greater than the third angle of inclination formed by the tangent of the outer end of the first convex portion at the inflection point with the reference plane.

[0015] According to one aspect of the present invention, the first inclination angle and the second inclination angle may be 1.2 to 2.5 times the third inclination angle.

[0016] According to one aspect of the present invention, the side notches include a curved portion that is curved in an arc shape, the first curve line or the second curve line has a first radius of curvature, the curved portion has a second radius of curvature, and the first radius of curvature and the second radius of curvature may be formed differently.

[0017] According to one aspect of the present invention, the first radius of curvature may be formed to be larger than the second radius of curvature.

[0018] According to one aspect of the present invention, the first radius of curvature may be 1.1 to 5.5 times the second radius of curvature.

[0019] According to one aspect of the present invention, the first radius of curvature may be 1.8 to 2.2 times the second radius of curvature.

[0020] In one aspect of the present invention, let the first radius of curvature be R11 and the second radius of curvature be R12, and let G11 be the first gap, which is the maximum gap between a virtual reference line extending in the longitudinal direction of the vent portion and the connecting notch, then R11 = A * R12 + G11(1.3≤ <A≤4.5)를 만족할 수 있다.

[0021] According to one aspect of the present invention, the side notch may include a first straight section connected to one end of the curved section and connected in a straight line, and a second straight section connected to the other end of the curved section and connected in a straight line.

[0022] According to one aspect of the present invention, an inflection point is formed in the connecting notch where the first curve line and the second curve line meet, and the acute angle of inclination at the inflection point, which is located in the central part of the width direction of the vent portion and meets a virtual reference line extending in the length direction of the vent portion, can be formed at 5 to 60 degrees.

[0023] According to one aspect of the present invention, an inflection point is formed in the connecting notch where the first curve line and the second curve line meet, and the acute angle of inclination at the inflection point, which is located in the center of the width direction of the vent portion and meets a virtual reference line extending in the length direction of the vent portion, can be 10 to 30 degrees.

[0024] According to one aspect of the present invention, the first curve line may be formed of a curve having a plurality of radii of curvature.

[0025] According to one aspect of the present invention, the first curve line comprises a first part, a second part connected to one end in the longitudinal direction of the first part, and a third part connected to the other end in the longitudinal direction of the first part, and the radius of curvature of the first part may be formed to be larger than the radii of curvature of the second part and the third part.

[0026] According to one aspect of the present invention, the first gap, which is the maximum gap with the connecting notch in a virtual reference line extending in the longitudinal direction of the vent portion, may be 0.05 to 0.4 times the second gap, which is the maximum gap with the first side notch in the virtual reference line.

[0027] According to one aspect of the present invention, the vent portion includes two side notches, and the two side notches may be formed to surround the connecting notch by 50% to 90%.

[0028] According to one aspect of the present invention, the connecting notch, the side notches, the first convex portion, and the second convex portion may be formed on a surface facing the outside of the case.

[0029] According to one aspect of the present invention, the connecting notch, the side notches, the first convex portion, and the second convex portion may be formed on a surface facing the inside of the case.

[0030] According to one aspect of the present invention The first convex portion and the second convex portion may be formed on a surface facing the outside of the case, and the connecting notch and the side notch may be formed on a surface facing the inside of the case.

[0031] According to one aspect of the present invention, the first convex portion and the second convex portion may be formed on a surface facing the inside of the case, and the connecting notch and the side notch may be formed on a surface facing the outside of the case.

[0032] According to one aspect of the present invention, the vent portion may further include a support rib that protrudes from the outside of the side notch and surrounds the side notch. Effects of the invention

[0033] According to a secondary battery according to one embodiment of the present invention, a first convex portion and a second convex portion are formed in the vent portion, and a connecting notch formed by a curve between the first convex portion and the second convex portion is formed, so that stress is concentrated in the dome-shaped first convex portion and the second convex portion, allowing the vent portion to be easily opened at a preset pressure. In addition, since the heights of the first convex portion and the second convex portion are formed differently, the notch can be easily and safely broken at a preset pressure even in various environments where pressure increases.

[0034] Furthermore, if the connecting notch includes convex curve lines in different directions, the pressure-receiving area increases compared to a straight line, allowing for accurate and easy fracture at a preset fracture pressure. Additionally, since the pressure-receiving area increases, the overall rigidity of the vent section can be designed to be high, and consequently, when the connecting notch fractures, the vent section can open wide under a large force. Brief explanation of the drawing

[0035] FIG. 1 is a perspective view illustrating a secondary battery according to a first embodiment of the present invention. Figure 2 is a cross-sectional view taken along the line A1-A1 in Figure 1. FIG. 3 is a plan view illustrating a cap assembly according to a first embodiment of the present invention. FIG. 4 is a plan view illustrating a vent portion according to a first embodiment of the present invention. FIG. 5 is a drawing partially illustrating a connecting notch according to a first embodiment of the present invention. FIG. 6 is a perspective view illustrating a vent portion according to a first embodiment of the present invention. Figure 7 is a cross-sectional view taken along the line A2-A2 in Figure 3. Figure 8 is a cross-sectional view taken along the line A3-A3 in Figure 6. Figure 9 is a cross-sectional view taken along the line A4-A4 in Figure 6. Figure 10 is a cross-sectional view taken along the line A5-A5 in Figure 6. FIG. 11 is a perspective view illustrating a vent portion according to a second embodiment of the present invention. Figure 12 is a cross-sectional view taken along the line A6-A6 in Figure 11. FIG. 13 is a perspective view of a vent portion viewed from below according to a third embodiment of the present invention. Figure 14 is a cross-sectional view taken along the line A7-A7 in Figure 13. FIG. 15 is a cross-sectional view taken of the portion where the connecting notch and the first side notch are located in the vent portion according to the fourth embodiment of the present invention. FIG. 16 is a cross-sectional view taken of the portion where the connecting notch and the second side notch are located in the vent portion according to the fourth embodiment of the present invention. FIG. 17 is a cross-sectional view taken of the portion where the connecting notch and the first side notch are located in the vent portion according to the fifth embodiment of the present invention. FIG. 18 is a cross-sectional view taken of the portion where the connecting notch and the second side notch are located in the vent portion according to the fifth embodiment of the present invention. FIG. 19 is a plan view illustrating a vent portion according to the 6th embodiment of the present invention. FIG. 20 is a perspective view illustrating a secondary battery according to the seventh embodiment of the present invention. FIG. 21 is a drawing illustrating a vent protection film according to the seventh embodiment of the present invention. Specific details for implementing the invention

[0036] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0037] The terms used in this invention are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this invention, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0038] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that in the accompanying drawings, identical components are indicated by the same reference numerals whenever possible. Furthermore, detailed descriptions of known functions and configurations that may obscure the essence of the present invention will be omitted. For the same reason, some components in the accompanying drawings may be exaggerated, omitted, or schematically depicted.

[0039] A secondary battery according to one embodiment of the present invention will be described below.

[0040] FIG. 1 is a perspective view illustrating a secondary battery according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line A1-A1 in FIG. 1, and FIG. 3 is a plan view illustrating a secondary battery according to a first embodiment of the present invention.

[0041] Referring to FIGS. 1 to 3, the secondary battery (100) according to the present embodiment may include an electrode assembly (10) including a positive electrode (11) and a negative electrode (12), a case (30) that accommodates the electrode assembly (10), a cap plate (21) coupled to the case (30), terminals (23, 24) installed on the cap plate (21), an upper insulating member (29) disposed between the cap plate (21) and the electrode assembly (10), and a vent portion (50) disposed on the cap plate (21).

[0042] The electrode assembly (10) performs charging and discharging and can be made in various forms such as an all-solid electrode assembly, a lithium-ion electrode assembly, a sodium-ion electrode assembly, etc.

[0043] The electrode assembly (10) includes an anode (11), a cathode (12), and a separator (13) interposed between the anode (11) and the cathode (12), and the anode (11), separator (13), and cathode (12) may be formed in a stacked structure or in a structure wound in the form of a jelly roll.

[0044] Additionally, the electrode assembly (10) may be structured such that an anode (11) and a cathode (12) are alternately inserted between separators (13) that are folded in a zigzag shape. Furthermore, the electrode assembly (10) may be formed in various forms, such as an all-solid type without a separator. The separator may be a material such as an electrically non-conductive polymer or ceramic material that separates the anode and cathode while allowing the permeation of the electrolyte and / or the movement of charge carriers. The electrode assembly (10) may also be implemented in various forms, such as an all-solid type in which there is no separate separator and the solid electrolyte performs both the roles of the electrolyte and the separator.

[0045] In this embodiment, the z-axis direction (or vertical direction) may mean a direction perpendicular to, for example, the cap or cap plate (21) (or the corresponding opening in the case (30)). That is, a direction perpendicular to the surface of the cap or cap plate (21), particularly the main surface. The x-axis and y-axis directions (or horizontal direction or horizontal plane) may mean a direction parallel to, for example, the cap or cap plate (21) (for example, a direction parallel to the surface of the cap or cap plate (21), particularly the main surface) or the opening in the case (30). The x-axis direction and the y-axis direction may be located along, for example, the smallest horizontal expansion direction and the largest horizontal expansion direction of the case (30), respectively.

[0046] With respect to the case (30), the direction perpendicular to the opening of the cap or cap plate (21) and the case (30) (z-axis direction) may be referred to as the longitudinal direction of the case (30). In a plane perpendicular to the longitudinal direction, the smallest expansion direction of the case (30) may also be referred to as the thickness direction of the case (30), which may coincide with the x-axis direction. In a plane perpendicular to the longitudinal direction, the largest expansion direction of the case (30) may also be referred to as the width direction of the case (30), which may or may not be perpendicular to the thickness direction and may coincide with the y-axis direction. The largest expansion direction of the case (30) may be, for example, the longitudinal direction or the width direction.

[0047] With respect to other configurations (e.g., parts, structures, elements, etc.), particularly configurations that may have a planar or substantially planar shape (e.g., cap plate (21) and vent portion (50)), the largest extension direction of the configuration may be referred to as the longitudinal direction (or length direction) of the configuration. The smallest extension direction of the configuration (e.g., a direction perpendicular to the main plane of the object) may be referred to as the thickness direction of the configuration. In a plane perpendicular to the thickness direction (lateral extension), the smallest extension direction of the configuration may be referred to as the width direction (or lateral direction) of the configuration.

[0048] The positive electrode (11) and the negative electrode (12) may include a coated portion, which is an area where an active material is applied to a metal foil, and a non-coated portion, where no active material is applied. The positive electrode non-coated portion (15) may protrude from the side end of the positive electrode (11), and the negative electrode non-coated portion (16) may protrude from the side end of the negative electrode (12). The positive electrode non-coated portion (15) and the negative electrode non-coated portion (16) may protrude in the same direction, but may protrude in a direction (z-axis direction) toward the cap plate (21).

[0049] The positive electrode blank (15) and the negative electrode blank (16) are formed in the shape of tabs and can be spaced apart in the width direction (y-axis direction) of the case (30). The tabs can be formed integrally with the electrodes and formed by notching. Additionally, the tabs may be members that are separately coupled to the electrodes. The positive electrode blank (15) and the negative electrode blank (16) can be stacked in the thickness direction (x-axis direction) of the case (30).

[0050] Additionally, the positive electrode unconnected portion (15) can be connected to the first terminal (23) via a current collector (41), and the negative electrode unconnected portion (16) can be connected to the second terminal (24) via a current collector (42).

[0051] A separator (13) is placed between the positive electrode (11) and the negative electrode (12), and the separator (13) prevents short circuits and enables the movement of ions. If the secondary battery (100) is made of an all-solid-state battery, a solid electrolyte may be placed between the positive electrode (11) and the negative electrode (12) instead of the separator (13).

[0052] The case (30) may be formed in the shape of a box having an internal space for accommodating the electrode assembly (10). The case (30) may be formed in various shapes, such as prismatic or cylindrical. A single electrode assembly (10) or multiple electrode assemblies (10) may be inserted into the case (30).

[0053] The case (30) may have a prism shape (i.e., at least substantially a prism shape), and in particular may have a square (quadrilateral) prism shape, such as a rectangular prism shape (i.e., at least substantially a rectangular prism shape). Alternatively, the case and / or housing may have a cylindrical shape, for example. An opening may be formed in the case (30) for inserting, for example, an electrode assembly into the case (30). The opening may be formed on at least one side of the case (e.g., a surface, a top side, or a top surface). In some examples, the opening may extend across the entire side of the case (e.g., the entire top or top surface).

[0054] An electrolyte may be contained together with an electrode assembly (10) inside the case (100). The electrolyte may be in the form of a liquid, solid, or gel.

[0055] The cap plate (21) is made of a plate material that covers the opening of the case (30) and may have a shape corresponding to the shape of the opening of the case (30). The cap plate (21) may be fixed to the case (30) by welding.

[0056] In the cap plate (21), an electrolyte injection port (H1) for injecting the electrolyte and a vent hole (H2) in which a vent portion (50) is installed may be formed. A sealing plug (28) that blocks the electrolyte injection port (H1) is installed in the electrolyte injection port (H1), and a vent portion (50) that opens at a preset pressure may be formed in the vent hole (H2).

[0057] An upper insulating member (29) may be disposed on the lower part of the cap plate (21), and the upper insulating member (29) may be formed as a plate parallel to the cap plate (21) and may extend along the longitudinal direction (y-axis direction) of the cap plate (21).

[0058] Terminals (23, 24) are coupled to the cap plate (21), and one or two terminals (23, 24) may be installed on the cap plate (21). When two terminals (23, 24) are installed on the cap plate (21), the first terminal (23) may be a positive terminal and the second terminal (24) may be a negative terminal. When one terminal is installed on the cap plate (21), the case (30) may be charged as a negative terminal.

[0059] The first terminal (23) and the second terminal (24) may be plate-shaped. As long as the shape enables an effective electrical connection to an external load, the first terminal (23) and the second terminal (24) may be used in any form including, but not limited to, rods, tubes, studs, posts, buttons, or pins, and the first terminal (23) and the second terminal (24) may be bent or straight. An insulating gasket (25) may be installed between the first terminal (23) and the cap plate (21), and an insulating gasket (26) may also be installed between the second terminal (24) and the cap plate (21). Additionally, the gaskets (25, 26) may extend downward and be located between the current collector (41, 42) and the cap plate (21). The gaskets (25, 26) may be made of a single component or divided into multiple components.

[0060] The first terminal (23) is electrically connected to the positive electrode unconnected portion (15) via the first current collector (41), and the second terminal (24) can be electrically connected to the negative electrode unconnected portion (16) via the second current collector (42).

[0061] The first terminal (23) and the second terminal (24) are formed in a plate shape, and a hole may be formed in the center of the first terminal (23) and the second terminal (24) into which a connecting column of the first current collecting member (41) or the second current collecting member (42) is inserted.

[0062] The electrode assembly (10) may include two anode-free arrays having the same polarity, and the anode-free arrays may be arranged so as not to overlap in the width direction (y-axis direction) and thickness direction (x-axis direction) of the electrode assembly (10). The anode-free arrays may be welded to the first current collector (41).

[0063] Additionally, the electrode assembly (10) may include two negative electrode non-removable arrays having the same polarity, and the negative electrode non-removable arrays may be arranged so as not to overlap in the width direction (y-axis direction) and thickness direction (x-axis direction) of the electrode assembly (10). The negative electrode non-removable arrays may be welded to the first current collector (41).

[0064] FIG. 4 is a plan view illustrating a vent portion according to a first embodiment of the present invention, FIG. 5 is a drawing partially illustrating a connecting notch according to a first embodiment of the present invention, FIG. 6 is a perspective view illustrating a vent portion according to a first embodiment of the present invention, and FIG. 7 is a cross-sectional view taken along the line A2-A2 in FIG. 3.

[0065] Referring to FIGS. 4 through 7, the vent portion (50) is formed in a plate shape and opens at a preset pressure. The vent portion (50) may be formed in an elliptical shape, i.e., a track-shaped plate in which two arcs are connected by a straight line. However, the present invention is not limited thereto. Other shapes including rounded sides and / or straight sides, such as squares, rectangles, polygons, or circles, may also be applied.

[0066] The vent portion (50) may extend along the length direction (y-axis direction) of the cap plate (21), but the present invention is not limited thereto and may be arranged to extend along the width direction (x-axis direction) of the cap plate (21).

[0067] Additionally, the vent portion (50) may be fixed to the cap plate (21) by welding. Alternatively, the vent portion (50) may be fixed to the cap plate (21) by another method of firmly securing it to the cap plate (21). The vent portion (50) may be fixed to the lower surface of the cap plate (21), but may also be fixed to the upper surface of the cap plate (21). The vent portion (50) may be inserted between the upper and lower portions of the cap plate (21) to secure the vent portion (50) to the cap plate (21).

[0068] The vent portion (50) may include two side notches (52, 53) and a connecting notch (51) connecting the side notches (52, 53). The connecting notch (51) and the side notches (52, 53) may be formed as long, continuous grooves and may be formed as grooves having a trapezoidal cross-section. However, the present invention is not limited thereto, and the connecting notch (51) and the side notches (52, 53) may have cross-sections of various shapes, such as triangles or arcs.

[0069] The vent portion (50) may form a portion that is weakened compared to an adjacent or surrounding portion to create a connecting notch (51) and a side notch (52, 53). The connecting notch (51) and the side notch (52, 53) may be in the form of notches having a groove shape on the surface of the vent material, or the connecting notch (51) and the side notch (52, 53) may be formed by weakening the vent material, such as through chemical, thermal, compression, or radiation. The connecting notch (51) and the side notch (52, 53) may be configured to break easily when a specific predetermined breaking pressure is reached within the secondary battery. The pressure may be a pressure difference between the inside and outside of the secondary battery (100), and may be caused, for example, by gas formation within the secondary battery or by the expansion of the electrolyte and / or the electrode assembly (10).

[0070] The notches (51, 52, 53) may be intentionally introduced weak lines or regions and may be configured to break (e.g., bending and / or rupturing, opening, folding and / or other deformation) at a preset specific breaking pressure. This allows the vent structure to be opened. Each notch (51, 52, 53) may be, for example, a structurally weakened part of the vent structure, which may be formed, for example, by the removal and / or deformation of material. The notches may be formed in the base of the vent (e.g., a substrate such as a plate or slab) as described below.

[0071] The vent portion (50) may be configured, for example, to seal the electrolyte of the secondary battery. The vent portion (50) may be configured to open as the internal pressure of the secondary battery (e.g., case and / or housing) increases (e.g., at a preset pressure, for example, when the internal pressure is equal to or greater than the preset pressure). The vent portion (50) may be configured to allow gas (and optionally liquid) to be discharged from inside the secondary battery when opened.

[0072] In this embodiment, the vent portion (50) may include a base having a first side and a second side. Here, the base represents a plate forming the vent portion (50), the first side represents the upper side of the base, i.e., an outer side facing the outside of the secondary battery, and the second side represents the lower side of the base, i.e., an inner side facing the inside of the secondary battery.

[0073] At this time, the connecting notch (51) and the side notch (52, 53) may be formed on the first side of the base, that is, on the upper side of the base. Alternatively, the connecting notch (51) and the side notch (52, 53) may be formed on the second side of the base, that is, on the lower side of the base.

[0074] Additionally, the connecting notch (51) and the side notches (52, 53) can be broken at a preset pressure. The connecting notch (51) may include a first curve line (51a) and a second curve line (51b) formed by a curve. The first curve line (51a) and the second curve line (51b) may be formed in an arc shape and may protrude convexly in different directions.

[0075] The first curve line (51a) may protrude convexly toward one side end of the vent portion (50) (in the -x-axis direction), and the second curve line (51b) may protrude convexly toward the other side end of the vent portion (50) (in the x-axis direction). Accordingly, the first curve line (51a) and the second curve line (51b) may protrude convexly in opposite directions to form a wave shape or an S shape.

[0076] Here, the inflection point (CP1) where the first curve line (51a) and the second curve line (51b) meet can be formed at the center of the longitudinal direction (y-axis direction) of the connecting notch (51). Additionally, the first curve line (51a) and the second curve line (51b) have the same radius of curvature, and the first curve line (51a) and the second curve line (51b) can be formed to have a first radius of curvature (R11). Accordingly, the connecting notch (51) can be formed point-symmetric with respect to the inflection point (CP1).

[0077] The connecting notch (51) may be connected at an angle to, for example, the two side notches (52 53) (e.g., may meet or intersect), where the angle (e.g., the smallest angle formed between each break line) may be, for example, between 20° and 90°, for example, 45° or 60° or greater and / or 90°, 80° or 70° or less. The two side notches (52 53) may be spatially separated from each other (e.g., may not be directly connected only by the connecting notch (51) (indirectly)) or alternatively connected to each other, for example, may form part of a single break line.

[0078] Meanwhile, the two side notches (52, 53) are formed convexly in opposite directions, but may protrude convexly toward the outer side in the longitudinal direction (y-axis direction) of the vent portion (50). The first side notch (52) and the second side notch (53) are connected to the connecting notch (51), and the first side notch (52) and the second side notch (53) have the same structure and may be arranged symmetrically.

[0079] The first side notch (52) may include a curved section (52a) that is curved in an arc shape, a first straight section (52b) that is connected to one end of the curved section (52a) and is connected in a straight line, and a second straight section (52c) that is connected to the other end of the curved section (52a) and is connected in a straight line.

[0080] The first straight section (52b) and the second straight section (52c) are connected in the longitudinal direction (y-axis direction) of the cap plate (21) and can be arranged parallel to each other. The curved section (52a) is formed as an arc having a second radius of curvature (R12) and is formed to partially wrap around the connecting notch (51).

[0081] Additionally, the second side notch (53) may include a curved section (53a) that is curved in an arc shape, a first straight section (53b) that is connected to one end of the curved section (53a) and is connected in a straight line, and a second straight section (53c) that is connected to the other end of the curved section (53a) and is connected in a straight line. Additionally, the connecting notch (51) may be connected to the longitudinal central portion of the first side notch (52) and the second side notch (53).

[0082] The side notches (52, 53) may encircle 25% to 100% of the length of the connecting notch (51), preferably 50% to 90%, and in one example, 60% to 80% (i.e., encircle the connecting notch (51) according to the corresponding portion of the length). The length of the connecting notch (51) is, for example, the distance between the two points furthest apart from each other at the connecting notch (51) and / or the length of the (curved) path through which the connecting notch (51) extends. The connecting notch (51) may be considered "encircled" by two side notches (52, 53) if the side notches (52, 53) are placed on both sides of the connecting notch (510) (e.g., in a direction perpendicular to the connecting notch (51)).

[0083] The first side notch (52) and the second side notch (53) are spaced apart and can be formed to partially wrap around the connecting notch (51). The connecting notch (51) can be located on the concave inner side of the mutually facing curved portions (52a, 53a) of the side notches (52, 53). Here, the first side notch (52) and the second side notch (53) can wrap around the connecting notch (51) by 50% to 90%.

[0084] One or both of the first straight section (52b) and the second straight section (52c) may be smoothly connected to the curved section (i.e., without twisting or abrupt bending), for example, connected tangentially to the corresponding end of the curved section. One or both of the first straight section (52b) and the second straight section (52c) may extend parallel or substantially parallel to the greatest extension direction (vertical direction) of the vent section (50) and / or the greatest extension direction (vertical direction) of the side of the cap or case where the vent structure is formed. The first straight section (52b) and the second straight section (52c) may be parallel or substantially parallel to each other. One or more side notches (52, 53) may have a U-shape (where the curved section connects the two straight legs / linear sections). As described in this specification, two directions or elements being substantially parallel means that each direction and element are positioned at an angle between -20° and 20° relative to each other (e.g., extension or projection), and in some examples between -10° and 10°, in one example between -5° and 5°, and in another example between -2° and 2°.

[0085] The first gap (G11), which is the maximum gap with the connecting notch (51) in the virtual reference line (SL1) that is located in the central part of the width direction (x-axis direction) of the vent portion (50) and extends in the length direction (y-axis direction) of the vent portion (50), can be 0.05 to 0.4 times the second gap (G12), which is the maximum gap with the first side notch (52) in the virtual reference line (SL1).

[0086] Meanwhile, as shown in FIG. 5, the acute angle of inclination (K11) at which the tangent (SL2) at the inflection point (CP1) meets the virtual reference line (SL1) can be 5 to 60 degrees. Preferably, the acute angle of inclination (K11) can be 10 to 30 degrees.

[0087] The first radius of curvature (R11) and the second radius of curvature (R12) are formed differently, and the first radius of curvature (R11) may be formed larger than the second radius of curvature (R12). The first radius of curvature (R11) may be 1.2 to 5.5 times the second radius of curvature (R12), and the first radius of curvature (R11) may also be 1.8 to 2.2 times the second radius of curvature (R12).

[0088] The equation 1st radius of curvature (R11) = A * 2nd radius of curvature (R12) + 1st interval (G11) can be satisfied. Here, 1.3 ≤ <A≤4.5을 만족하는 상수로 이루어질 수 있다.

[0089] If the first radius of curvature (R11) is formed to be larger than the second radius of curvature (R12), the line of the connecting notch (51) is formed as a gentle curve, so that when the connecting notch (51) is broken, the connecting notch can be easily broken along the curve.

[0090] In addition, if the first radius of curvature (R11) is formed to be smaller than the second radius of curvature (R12), there is a problem in that the height difference of the vent piece that breaks and folds becomes too large. If the height difference of the vent piece is large, the higher part touches the upper structure and cannot be opened properly, or there is a problem in that a large amount of space must be secured at the top.

[0091] Referring to FIGS. 6 and 7, the vent portion (50) may include a first convex portion (56) and a second convex portion (57) formed between a connecting notch (51) and side notches (52, 53). The first convex portion (56) may be located between one end of the connecting notch (51) and the side notches (52, 53), and the second convex portion (57) may be located between one end of the connecting notch (51) and the side notches (52, 53). The first convex portion and the second convex portion may be provided as a pair of convex portions. However, the vent portion is not limited to two convex portions and may include more convex portions spaced apart by additional connecting notches. For example, three convex sections can be formed by two spaced-apart connecting notches, and four convex sections can be formed by connecting notches having three spaced-apart curved lines.

[0092] The first convex portion (56) and the second convex portion (57) may include dome-shaped, concave, or curved portions. The first convex portion (56) and the second convex portion (57) may protrude from a plane extending between the connecting notch (51) and one or more side notches (52, 53) (e.g., where the plane is the plane on which the notch is placed where the first convex portion (56) and the second convex portion (57) are positioned). Or the first convex portion (56) and the second convex portion (57) may be bent in the thickness direction of the vent portion (50) (i.e., away from the plane of the vent portion or bottom). The first convex portion (56) and the second convex portion (57) may protrude outward (away from the inside of the case) or inward (toward toward the inside of the case). The first convex portion (56) and the second convex portion (57) may be continuously bent throughout the entire convex portion, for example, from the connecting notch (51) to one or more side notches (52, 53). The first convex portion (56) and the second convex portion (57) may not include, for example, flat or straight portions. The bending curvature (e.g., the reciprocal of the bending radius) or the bending angle or slope (e.g., relative to the reference plane) of the first convex portion (56) and the second convex portion (57) may be smaller than the bending curvature and / or bending angle / slope of the first and second concave portions, respectively, and in some examples may be substantially smaller (e.g., at least 2 times smaller, in some examples at least 3 times smaller, in one example at least 5 times smaller, and in another example at least 10 times smaller).

[0093] The first convex portion (56) and the second convex portion (57) may be spaced apart and positioned adjacently with the connecting notch (51) in between. For example, the first convex portion (56) may be positioned to the left of the connecting notch (51), and the second convex portion (57) may be positioned to the right of the connecting notch (51).

[0094] A support plate (58) can be formed on the outer side of the first convex portion (56) and the second convex portion (57), and is made of a flat plate and inserted between the cap plate (21) and the upper insulating member (29).

[0095] The first convex portion (56) and the second convex portion (57) may extend from the part where the connecting notch (51) and the first side notch (52) are connected to the part where the connecting notch (51) and the second side notch (53) are connected. A concave portion may be formed on the opposite side of the first convex portion (56) and the second convex portion (57).

[0096] Both the first convex portion (56) and the second convex portion (57) may protrude toward the upper side of the base, i.e., the first side, or both the first convex portion (56) and the second convex portion (57) may protrude toward the lower side of the base, i.e., the second side. Alternatively, the first convex portion (56) may protrude toward the upper side of the base, and the second convex portion (57) may protrude toward the lower side of the base.

[0097] The height of the first convex portion (56) may be formed differently from the height of the second convex portion (57), and the height of the first convex portion (56) may be formed to be greater than the height of the second convex portion (57).

[0098] Accordingly, the first distance (D11) between the top of the first convex portion (56) and the inner end of the vent member (50) can be formed to be larger than the second distance (D12) between the top of the second convex portion (57) and the inner end of the vent member (50). The first distance (D11) can be 1.02 to 2.5 times the second distance (D12). If the heights of the first convex portion (56) and the second convex portion (57) are formed differently, the notch can be broken more easily due to the imbalance of forces.

[0099] FIG. 8 is a cross-sectional view taken along the line A3-A3 in FIG. 6, FIG. 9 is a cross-sectional view taken along the line A4-A4 in FIG. 6, and FIG. 10 is a cross-sectional view taken along the line A5-A5 in FIG. 6.

[0100] Referring to FIGS. 6, 8 through 10, the connecting notch (51) may include an inflection point (CP1) where a first curve line (51a) and a second curve line (51b) meet, a first reference point (CP2) where the first curve line (51a) forms a maximum distance from a reference line (SL1) extending longitudinally from the center of the width direction of the vent portion, and a second reference point (CP3) where the second curve line (51b) forms a maximum distance from the reference line (SL1). In other variations, additional curve lines meeting at midpoints instead of inflection points may be provided. For example, three curve lines may be arranged to meet at midpoints, and the ends of the three curve lines may be spaced apart from each other by 120 degrees (of course, other angles may also be used). In another example, four curve lines may be arranged to meet at a midpoint, and the ends of the four curve lines may be spaced 90 degrees apart (of course, other angles may also be used). In another embodiment, the lengths of the curve lines forming the connecting notch may be the same, or one or more may have different lengths.

[0101] Additionally, the first inclination angle (K21) formed by the tangent of the outer end of the first convex portion (56) of the vent portion (50) in the width direction at the first reference point (CP2) with a virtual reference plane (SF1) parallel to the cap plate (21), and the second inclination angle (K22) formed by the tangent of the outer end of the first convex portion (56) in the width direction at the second reference point (CP3) with the reference plane (SF1) can be formed larger than the third inclination angle (K23) formed by the tangent of the outer end of the first convex portion (56) in the width direction at the inflection point (CP1) with the reference plane (SF1).

[0102] Here, the outer end in the width direction of the first convex portion (56) at the first reference point (CP2), the second reference point (CP3), or the inflection point (CP1) means the outer end of the first convex portion (56) that meets the line extending in the width direction of the first convex portion (56) at the first reference point (CP2), the second reference point (CP3), or the inflection point (CP1).

[0103] In addition, the first inclination angle (K21) and the second inclination angle (K22) may be 1.2 to 2.5 times the third inclination angle (K23).

[0104] For example, the first inclination angle (K21) and the second inclination angle (K22) may be 6 to 25 degrees, and the third inclination angle (K23) may be 5 to 15 degrees.

[0105] If the first inclination angle (K21) and the second inclination angle (K22) are formed to be larger than the third inclination angle (K23), when swelling from the center, uniform deformation of the center and sides is induced, allowing the notch to easily break. In particular, if the first inclination angle (K21) and the second inclination angle (K22) are formed to be 1.2 to 2.5 times the third inclination angle (K23), the opening pressure of the vent portion (50) can be controlled more accurately. Alternatively, the third inclination angle (K23) may be at least 10% smaller than the first inclination angle (K21) and the second inclination angle (K22), at least 20% smaller in some examples, or at least 30% smaller in some examples.

[0106] According to the present embodiment, a first convex portion (56) and a second convex portion (57) are formed, and since the heights of the first convex portion (56) and the second convex portion (57) are formed differently, the notch can be easily and safely broken at a preset pressure.

[0107] If the connecting notch (51) is connected in a curve similar to an S, the pressure-receiving area increases compared to a straight line, so it can be broken accurately and easily at a preset breaking pressure. In addition, when the connecting notch (51) is broken, it can be broken easily and quickly along the curve. By allowing it to break easily and quickly along the curve, the connecting notch can start opening the vent portion.

[0108] Additionally, at the side notches (52, 53), the curved portion (52a) can be broken, while the first straight portion (52b) and the second straight portion (52c) can be folded without being broken. When the first straight portion (52b) and the second straight portion (52c) are formed, the vent piece can be easily bent to quickly secure a discharge space. Additionally, the first straight portion (52b) and the second straight portion (52c) may be partially or completely broken depending on the breaking environment. The side notches (52, 53) allow the vent portion to be opened as much as possible after opening is initiated by the connecting notch (51). Furthermore, the side notches (52, 53) can minimize obstruction or interference from the vent piece (50a, 50b) during gas discharge.

[0109] Meanwhile, in some cases, the connecting notch (51) may not break and the side notch (52, 53) may break first. In this case, the curved portion (52a), the first straight portion (52b), and the second straight portion (52c) may all break, forming two openings on both sides, thereby securing sufficient space for gas to be discharged.

[0110] A secondary battery according to a second embodiment of the present invention will be described below.

[0111] FIG. 11 is a perspective view illustrating a vent portion according to a second embodiment of the present invention, and FIG. 12 is a cross-sectional view taken along the line A6-A6 in FIG. 11.

[0112] Referring to FIGS. 11 and 12, the secondary battery according to the second embodiment has the same structure as the secondary battery according to the first embodiment described above, except for the vent portion (150), so a redundant description of the same configuration is omitted.

[0113] The vent portion (150) may include two side notches (152, 153) and a connecting notch (151) connecting the side notches (152, 153). The side notches (152, 153) and the connecting notch (151) may be formed on the outer surface of the vent portion (150) facing the outside of the case.

[0114] The connecting notch (151) and side notch (152, 153) according to the second embodiment are formed with the same structure as the connecting notch and side notch of the first embodiment described above.

[0115] Additionally, the vent portion (150) may further include a first support rib (154) located on the outside of the first side notch (152) and surrounding the first side notch (152), and a second support rib (155) located on the outside of the second side notch (153) and surrounding the second side notch (153).

[0116] The first support rib (154) is positioned further from the center of the vent portion (150) than the first side notch (152) and may be connected to the top of the first side notch (152), but the present invention is not limited thereto, and the first support rib (154) may be positioned spaced apart from the first side notch (152).

[0117] The first support rib (154) prevents deformation of the vent portion (150) and can serve to support the first side notch (152) so that it can be easily torn when the first side notch (152) breaks.

[0118] Additionally, the second support rib (155) is positioned further from the center of the vent portion (150) than the second side notch (153) and may be connected to the top of the second side notch (153), but the present invention is not limited thereto. The second support rib (155) prevents deformation of the vent portion (150) and may serve to support the second side notch (153) so that it can be easily torn when the second side notch (153) breaks.

[0119] Additionally, the vent portion (150) may include a first convex portion (156) and a second convex portion (157) formed between the connecting notch (151) and the side notches (152, 153). The first convex portion (156) may be located between one end of the connecting notch (151) and the side notches (152, 153), and the second convex portion (157) may be located between one end of the connecting notch (151) and the side notches (152, 153). For example, the first convex portion (156) may be positioned to the left of the connecting notch (151), and the second convex portion (157) may be positioned to the right of the connecting notch (151).

[0120] The first convex portion (156) and the second convex portion (157) may extend from the portion where the connecting notch (151) and the first side notch (152) are connected to the portion where the connecting notch (151) and the second side notch (153) are connected. A first concave portion (158) may be formed on the opposite side of the first convex portion (156), and a second concave portion (159) may be formed on the opposite side of the second convex portion (157).

[0121] A connecting notch (151) may be located in a valley portion (VL1) formed between a first convex portion (156) and a second convex portion (157). A first side notch (152) may be located between the first convex portion (156) and the first support rib (154) and between the second convex portion (157) and the first support rib (154), and a second side notch (153) may be located between the first convex portion (156) and the second support rib (155) and between the second convex portion (157) and the second support rib (155).

[0122] The first tangent angle (K31) formed by the tangent at the end adjacent to the connecting notch (151) in the first convex portion (156) with the virtual reference plane (SF1) parallel to the cap plate (21) can be formed to be smaller than the second tangent angle (K32) formed by the tangent at the end adjacent to the first side notch (152) or the second side notch (153) in the first convex portion (156) with the reference plane (SF1).

[0123] The first tangent angle (K31) may be 1 to 20 degrees, and the second tangent angle (K32) may be 2 to 30 degrees. Additionally, the first tangent angle (K31) may be 2 to 15 degrees, and the second tangent angle (K32) may be 2 to 25 degrees.

[0124] The second tangent angle (K32) can be 1.1 to 3.5 times the first tangent angle (K31). Additionally, the difference between the first tangent angle (K31) and the second tangent angle (K32) can be 1 to 10 degrees.

[0125] The third tangent angle (K33) formed by the tangent at the end adjacent to the connecting notch (151) in the second convex portion (157) with the virtual reference plane (SF1) parallel to the cap plate (21) can be formed to be smaller than the fourth tangent angle (K34) formed by the tangent at the end adjacent to the first side notch (152) or the second side notch (153) in the second convex portion (157) with the reference plane (SF1).

[0126] The fourth tangent angle (K34) may be 1.1 to 3.5 times the third tangent angle (K33). The difference between the third tangent angle (K33) and the fourth tangent angle (K34) may be 1 to 10 degrees.

[0127] The third tangent angle (K33) may be 1 to 20 degrees, and the fourth tangent angle (K34) may be 2 to 30 degrees. Additionally, the third tangent angle (K33) may be 2 to 15 degrees, and the fourth tangent angle (K35) may be 2 to 25 degrees.

[0128] As described above, according to the second embodiment, the first support rib (154) and the second support rib (155) are formed, thereby preventing deformation of the vent portion (150) and allowing the side notches (152, 153) to be easily torn.

[0129] In addition, since the tangential angle of the part connected to the connecting notch (151) in the first convex part (156) and the second convex part (157) is formed to be smaller than the tangential angle of the part connected to the side notch (152, 153) in the first convex part (156) and the second convex part (157), the connecting notch (151) placed in the center can be easily deformed upward by pressure, and the connecting notch (151) and the side notch (152, 153) can be easily broken.

[0130] A secondary battery according to the third embodiment of the present invention will be described below.

[0131] FIG. 13 is a perspective view of a vent portion according to a third embodiment of the present invention viewed from below, and FIG. 14 is a cross-sectional view taken along line A7-A7 in FIG. 13.

[0132] Referring to FIGS. 13 and 14, the secondary battery according to the third embodiment has the same structure as the secondary battery according to the first embodiment described above, except for the vent portion (160), so a redundant description of the same configuration is omitted.

[0133] The vent portion (160) may include two side notches (162, 163) and a connecting notch (161) connecting the side notches (162, 163). The side notches (162, 163) and the connecting notch (161) may be formed on the inner surface of the vent portion (160) facing the inside of the case. The connecting notch (161) and the side notches (162, 163) according to the third embodiment are formed with the same structure as the connecting notch and the side notch of the first embodiment described above.

[0134] Additionally, the vent portion (160) may further include a first support rib (164) located on the outside of the first side notch (162) and surrounding the first side notch (162), and a second support rib (165) located on the outside of the second side notch (163) and surrounding the second side notch (163). The first support rib (164) and the second support rib (165) may protrude toward the inside of the case.

[0135] The first support rib (164) may be positioned further from the center of the vent portion (160) than the first side notch (162), and the second support rib (165) may be positioned further from the center of the vent portion (160) than the second side notch (163).

[0136] Additionally, the vent portion (160) may include a first convex portion (166) and a second convex portion (167) formed between the connecting notch (161) and the side notches (162, 163). The first convex portion (166) and the second convex portion (167) may protrude toward the inside of the case.

[0137] The first convex portion (166) and the second convex portion (167) may be positioned with the connecting notch (161) in between. A first concave portion (168) may be formed on the opposite side of the first convex portion (166), and a second concave portion (169) may be formed on the opposite side of the second convex portion (167).

[0138] A connecting notch (161) may be located in a valley portion (VL2) formed between a first convex portion (166) and a second convex portion (167). A first side notch (162) may be located between the first convex portion (166) and the first support rib (164) and between the second convex portion (167) and the first support rib (164), and a second side notch (163) may be located between the first convex portion (166) and the second support rib (165) and between the second convex portion (167) and the second support rib (165).

[0139] The first tangent angle (K41) formed by the tangent at the end adjacent to the connecting notch (161) in the first concave portion (168) with the virtual reference plane (SF1) parallel to the cap plate (21) can be formed to be smaller than the second tangent angle (K42) formed by the tangent at the end adjacent to the first side notch (162) in the first concave portion (168) with the reference plane (SF1).

[0140] The first tangent angle (K41) may be 1 to 20 degrees, and the second tangent angle (K42) may be 2 to 30 degrees. Additionally, the first tangent angle (K41) may be 2 to 15 degrees, and the second tangent angle (K42) may be 2 to 25 degrees. The difference between the first tangent angle (K41) and the second tangent angle (K42) may be 1 to 10 degrees.

[0141] The third tangent angle (K43) formed by the tangent at the end adjacent to the connecting notch (161) in the second concave portion (169) with the virtual reference plane (SF1) parallel to the cap plate (21) can be formed to be smaller than the fourth tangent angle (K44) formed by the tangent at the end adjacent to the first side notch (162) in the second concave portion (169) with the reference plane (SF1).

[0142] The third tangent angle (K43) may be 1 to 20 degrees, and the fourth tangent angle (K44) may be 2 to 30 degrees. Additionally, the third tangent angle (K43) may be 2 to 15 degrees, and the fourth tangent angle (K44) may be 2 to 25 degrees. The difference between the third tangent angle (K43) and the fourth tangent angle (K44) may be 1 to 10 degrees.

[0143] As described above, according to the third embodiment, the side notches (162, 163) and the connecting notch (161) are formed on the inner surface facing the inside of the case from the vent portion (160), and the first convex portion (166) and the second convex portion (167) protrude toward the inside of the case, so that the side notches (162, 163), the connecting notch (161), the first convex portion (166), and the second convex portion (167) can be prevented from being damaged by external impact or pressure during transportation, etc.

[0144] In addition, since the tangential angle of the part connected to the connecting notch (161) in the first concave part (168) and the second concave part (169) is formed to be smaller than the tangential angle of the part connected to the side notch (162, 163) in the first concave part (168) and the second concave part (169), the connecting notch (161) and the side notch (162, 163) can be easily broken.

[0145] Hereinafter, a secondary battery according to the fourth embodiment of the present invention will be described.

[0146] FIG. 15 is a cross-sectional view taken of the portion where the connecting notch and the first side notch are located in the vent portion according to the fourth embodiment of the present invention, and FIG. 16 is a cross-sectional view taken of the portion where the connecting notch and the second side notch are located in the vent portion according to the fourth embodiment of the present invention.

[0147] Referring to FIGS. 15 and 16, the secondary battery according to the fourth embodiment has the same structure as the secondary battery according to the first embodiment described above, except for the vent portion (180), so a redundant description of the same configuration is omitted.

[0148] The vent portion (180) may include two side notches (182, 183) and a connecting notch (181) connecting the side notches (182, 183). The side notches (182, 183) and the connecting notch (181) may be formed on the inner surface of the vent portion (180) facing the inside of the case. The connecting notch (181) and the side notches (182, 183) according to the fourth embodiment are formed with the same structure as the connecting notch and the side notch of the first embodiment described above.

[0149] Additionally, the vent portion (180) may further include a first support rib (184) located on the outside of the first side notch (182) and surrounding the first side notch (182), and a second support rib (185) located on the outside of the second side notch (183) and surrounding the second side notch (183). The first support rib (184) and the second support rib (185) may protrude in a direction toward the outside of the case.

[0150] The first support rib (184) may be positioned further from the center of the vent portion (180) than the first side notch (182), and the second support rib (185) may be positioned further from the center of the vent portion (180) than the second side notch (183).

[0151] Additionally, the vent portion (180) may include a first convex portion (186) and a second convex portion (187) formed between the connecting notch (181) and the side notches (182, 183). The first convex portion (186) and the second convex portion (187) may protrude outward. A first concave portion (188) may be formed on the opposite side of the first convex portion (186), and a second concave portion (189) may be formed on the opposite side of the second convex portion (187).

[0152] A connecting notch (181) may be located in a peak (PK1) formed between a first concave portion (188) and a second concave portion (189). A first side notch (182) may be located between the first concave portion (188) and the first support rib (184) and between the second concave portion (189) and the first support rib (184), and a second side notch (183) may be located between the first concave portion (188) and the second support rib (185) and between the second concave portion (189) and the second support rib (185).

[0153] Hereinafter, a secondary battery according to the fifth embodiment of the present invention will be described.

[0154] FIG. 17 is a cross-sectional view taken of the portion where the connecting notch and the first side notch are located in the vent portion according to the fifth embodiment of the present invention, and FIG. 18 is a cross-sectional view taken of the portion where the connecting notch and the second side notch are located in the vent portion according to the fifth embodiment of the present invention.

[0155] Referring to FIGS. 17 and 18, the secondary battery according to the fifth embodiment has the same structure as the secondary battery according to the first embodiment described above, except for the vent portion (190), so a redundant description of the same configuration is omitted.

[0156] The vent portion (190) may include two side notches (192, 193) and a connecting notch (191) connecting the side notches (192, 193). The side notches (192, 193) and the connecting notch (191) may be formed on the outer surface of the vent portion (190) facing the outside of the case. The connecting notch (191) and the side notches (192, 193) according to the fifth embodiment are formed with the same structure as the connecting notch and the side notch of the first embodiment described above.

[0157] Additionally, the vent portion (190) may further include a first support rib (194) located on the outside of the first side notch (192) and surrounding the first side notch (192), and a second support rib (195) located on the outside of the second side notch (193) and surrounding the second side notch (193). The first support rib (194) and the second support rib (195) may protrude toward the inside of the case.

[0158] The first support rib (194) may be positioned further from the center of the vent portion (190) than the first side notch (192), and the second support rib (195) may be positioned further from the center of the vent portion (190) than the second side notch (193).

[0159] Additionally, the vent portion (190) may include a first convex portion (196) and a second convex portion (197) formed between the connecting notch (191) and the side notches (192, 193). The first convex portion (196) and the second convex portion (197) may protrude toward the inside of the case.

[0160] A first concave portion (198) may be formed on the opposite side of the first convex portion (196), and a second concave portion (199) may be formed on the opposite side of the second convex portion (197). A connecting notch may be located at a peak portion (PK2) formed between the first concave portion (198) and the second concave portion (199). A first side notch (192) may be located between the first concave portion (198) and the first support rib (194) and between the second concave portion (199) and the first support rib (194), and a second side notch (193) may be located between the first concave portion (198) and the second support rib (195) and between the second concave portion (199) and the second support rib (195).

[0161] Hereinafter, a secondary battery according to the 6th embodiment of the present invention will be described.

[0162] FIG. 19 is a plan view illustrating a vent portion according to the 6th embodiment of the present invention.

[0163] Referring to FIG. 19, the secondary battery according to the sixth embodiment has the same structure as the secondary battery according to the first embodiment described above, except for the vent portion (240), so a redundant description of the same configuration is omitted.

[0164] The vent portion (240) may include two side notches (242, 243) and a connecting notch (241) connecting the side notches (242, 243). The connecting notch (241) may include a first curve line (241a) and a second curve line (241b) formed by a curve. The first curve line (241a) and the second curve line (241b) may be formed in an arc shape and may protrude convexly in different directions.

[0165] The first curve line (241a) may protrude convexly toward one side of the vent portion (240), and the second curve line (241b) may protrude convexly toward the other side of the vent portion (240). The first curve line (241a) and the second curve line (241b) may have the same shape but may protrude convexly in opposite directions. For example, a line protruding in one direction may be bent like a bow in the direction of protrusion to form a bulge of the line.

[0166] The first curve line (241a) may be formed as a curve having multiple radii of curvature. The first curve line (241a) may include a first part (241aa) having a first radius of curvature (R21), a second part (241ab) having a second radius of curvature (R22) connected to one end of the first part (241aa) in the longitudinal direction, and a third part (241ac) having a third radius of curvature (R23) connected to the other end of the first part (241aa) in the longitudinal direction. The first radius of curvature (R21) is formed to be larger than the second radius of curvature (R22), and the first radius of curvature (R21) may be 1.1 to 2.5 times the second radius of curvature (R22). The second radius of curvature (R22) and the third radius of curvature (R23) can be formed identically.

[0167] Or the first radius of curvature (R21) may be larger than one or both of the second radius of curvature (R22) and the third radius of curvature (R23), for example, at least 10% larger, at least 25% larger in some examples, at least 50% larger in one example, or at least 100% larger in one example.

[0168] Meanwhile, the second curve line (241b) may be formed of a curve having multiple radii of curvature. The second curve line (241b) may include a first part (241ba), a second part (241bb) connected to one end of the first part (241ba) in the longitudinal direction, and a third part (241bc) connected to the other end of the first part (241ba) in the longitudinal direction.

[0169] The radius of curvature of the first part (241ba) is formed to be larger than the radius of curvature of the second part (241bb) and the third part (241bc), and the radius of curvature of the second part (241bb) and the radius of curvature of the third part (241bc) can be formed to be the same.

[0170] The two side notches (242, 243) may include a curved portion that protrudes convexly in opposite directions and is connected in an arc shape. The two side notches (242, 243) may be spaced apart and formed to partially wrap around the connecting notch (241). The curved portion of the side notches (242, 243) may have a fourth radius of curvature (R24).

[0171] The fourth radius of curvature (R24) may be formed to be smaller than the first radius of curvature (R21) and the second radius of curvature (R22), and the fourth radius of curvature (R24) may be 0.3 to 0.7 times the second radius of curvature (R22).

[0172] As in the sixth embodiment, if the first curve line (241a) and the second curve line (241b) have multiple radii of curvature, the design freedom of the connecting notch (241) is further increased, and the connecting notch (241) can be easily broken at a more precise pressure. As the length of the connecting notch increases, the pressure-receiving area also increases due to the increased notch length compared to the case where a single radius of curvature is present, making venting easier to occur.

[0173] Hereinafter, a secondary battery according to the seventh embodiment of the present invention will be described.

[0174] FIG. 20 is a perspective view illustrating a secondary battery according to the 7th embodiment of the present invention, and FIG. 21 is a drawing illustrating a vent protection film according to the 7th embodiment of the present invention.

[0175] Referring to FIGS. 20 and 21, the secondary battery (101) according to the seventh embodiment has the same structure as the secondary battery according to the first embodiment described above, except for the vent portion (130), so a redundant description of the same configuration is omitted.

[0176] The secondary battery (101) may be composed of a rectangular battery having a case (30) in the shape of a rectangular prism, and the vent portion (130) may be fixed to the bottom (35) of the case (30). The bottom (35) of the case (30) may be formed integrally with the case (30) or fixed to the case (30) by welding or the like.

[0177] An exhaust hole for discharging gas is formed in the bottom (35) of the case (30), and a stepped portion into which a vent portion (130) is inserted may be formed on the lower outer side of the exhaust hole (36).

[0178] The vent portion (130) is formed in the shape of a plate and can be fixed to the case (30) by welding. The vent portion (130) may include two side notches (132, 133) and a connecting notch (131) connecting the side notches (132, 133). Since the connecting notch (131) and the side notches (132, 133) are formed with the same structure as the connecting notch and side notches according to the first embodiment described above, a redundant description thereof is omitted.

[0179] Meanwhile, a vent protection film (60) may be installed on the lower part of the vent section (50). The vent protection film (60) may be made of a flexible film, and a connection hole (61) for discharging pressure may be formed in the vent protection film (60). Additionally, a fixing area (62) for fixing may be formed on the outer side of the vent protection film (61). The fixing area (62) may be adhered or fused to the vent section (50) or the cap plate (21).

[0180] As described above, according to the 10th embodiment, a vent portion (130) is formed on the bottom (35) of the case (30), so that the electrolyte can also be discharged when the vent portion (130) is opened.

[0181] Although an embodiment of the present invention has been described above, those skilled in the art may modify and change the present invention in various ways by adding, changing, deleting, or adding components, etc., without departing from the spirit of the present invention as described in the claims, and such modifications and changes are also to be included within the scope of the rights of the present invention. Explanation of the symbols

[0182] 100, 101: Secondary battery 10: Electrode assembly 11: Anode 12: Cathode 13: Separator 15: Anode non-existent part 16: Cathode non-cathode area 21: Cap plate 23: 1st terminal 24: 2nd terminal 25, 26: Gasket 28: Sealing plug 29: Upper insulating member 30: Case 41: First Servant 42: Second Servant 50, 130, 150, 160, 180, 190, 240: Vent section 51, 131, 151, 161, 181, 191, 241: Connecting notch 51a, 241a: 1st curve line 51b, 241b: 2nd curve line 52, 132, 152, 162, 182, 192, 242: 1st side notch 53, 133, 153, 163, 183, 193, 243: Second side notch 52a, 53a: Curved section 52b, 53b: First straight section 52c, 53c: Second straight section 58: Support plate 60: Vent protective film 61: Connection hole 62: Fixed area 56, 156, 166, 186, 196: First convex portion 57, 157, 167, 187, 197: Second convex portion 154, 164, 184, 194: First support rib 155, 165, 185, 195: Second support rib 158, 168, 188, 198: 1st concave area 159, 169, 189, 199: 2nd concave area 241aa, 241ba: Part 1 241ab 241bb: Part 2 241ac, 241bc: Part 3

Claims

Claim 1 A secondary battery comprising: a case; an electrode assembly inserted into the case; a cap plate coupled to the case; and a vent portion formed in the case or the cap plate; wherein the vent portion comprises a first convex portion and a second convex portion protruding and arranged adjacently to each other, a connecting notch located between the first convex portion and the second convex portion and connected by a curve, and two side notches connected to the connecting notch, wherein the side notch includes a curved portion connected by a curve, and the connecting notch is connected to an inner portion located between the two ends of the curved portion of the side notches along the longitudinal direction of the vent portion. Claim 2 A secondary battery according to claim 1, wherein the angle of inclination formed by the tangent of the first convex portion or the second convex portion at the portion connected to the connecting notch with the plane parallel to the cap plate is 1 to 20 degrees. Claim 3 A secondary battery according to claim 1, wherein the connecting notch includes a first curve line and a second curve line, and the first curve line and the second curve line protrude convexly in opposite directions. Claim 4 delete Claim 5 A secondary battery according to claim 1, wherein the first tangent angle formed by the tangent at the end adjacent to the connecting notch in the first convex portion with a virtual reference plane parallel to the cap plate is formed to be smaller than the second tangent angle formed by the tangent at the end adjacent to any one of the side notches in the first convex portion with the reference plane. Claim 6 A secondary battery according to claim 5, wherein the second tangent angle is 1.1 to 3.5 times the first tangent angle. Claim 7 In paragraph 3, the connecting notch includes an inflection point where the first curve line and the second curve line meet, a first reference point where the first curve line forms a maximum distance from a reference line extending in the longitudinal direction from the center of the width direction of the vent portion, and a second reference point where the second curve line forms a maximum distance from the reference line, wherein the first angle of inclination formed by the tangent of the outer end of the width direction of the first convex portion at the first reference point with a virtual reference plane parallel to the cap plate and the second angle of inclination formed by the tangent of the outer end of the width direction of the first convex portion at the second reference point with the reference plane are formed to be greater than the third angle of inclination formed by the tangent of the outer end of the width direction of the first convex portion at the inflection point with the reference plane. Claim 8 A secondary battery according to claim 7, wherein the first inclination angle and the second inclination angle are 1.2 to 2.5 times the third inclination angle. Claim 9 In paragraph 3, the first curve line or the second curve line has a first radius of curvature, the curved portion has a second radius of curvature, and the first radius of curvature and the second radius of curvature are different, a secondary battery. Claim 10 In claim 9, the first radius of curvature is larger than the second radius of curvature, a secondary battery. Claim 11 A secondary battery according to claim 9, wherein the first radius of curvature is 1.1 to 5.5 times the second radius of curvature. Claim 12 In claim 9, let the first radius of curvature be R11 and the second radius of curvature be R12, and let G11 be the first gap, which is the maximum gap between the connecting notch and a virtual reference line extending in the longitudinal direction of the vent portion, then R11 = A * R12 + G11(1.3≤ <A≤4.5)인, 이차 전지. Claim 13 A secondary battery according to claim 9, wherein the side notch comprises a first straight section connected to one end of the curved portion and connected in a straight line, and a second straight section connected to the other end of the curved portion and connected in a straight line. Claim 14 A secondary battery according to paragraph 3, wherein an inflection point is formed in the connecting notch where the first curve line and the second curve line meet, and the acute angle of inclination at the inflection point is 5 to 60 degrees, where the tangent line at the inflection point is located in the center of the width direction of the vent portion and meets a virtual reference line extending in the length direction of the vent portion. Claim 15 In claim 3, the secondary battery, wherein the first curve line is composed of a curve having a plurality of radii of curvature. Claim 16 A secondary battery according to claim 3, wherein the first curve line comprises a first part, a second part connected to one longitudinal end of the first part, and a third part connected to the other longitudinal end of the first part, and the radius of curvature of the first part is formed to be larger than the radii of curvature of the second part and the third part. Claim 17 A secondary battery according to claim 1, wherein the first gap, which is the maximum gap with the connecting notch in a virtual reference line extending in the longitudinal direction of the vent portion, is 0.05 to 0.4 times the second gap, which is the maximum gap with the first side notch in the virtual reference line. Claim 18 A secondary battery according to claim 1, wherein the two side notches are formed to surround the connecting notch by 50% to 90%. Claim 19 A secondary battery according to claim 1, wherein the connecting notch, the side notches, the first convex portion, and the second convex portion are formed on a surface facing the outside of the case. Claim 20 A secondary battery according to claim 1, wherein the connecting notch, the side notches, the first convex portion, and the second convex portion are formed on a surface facing the inside of the case. Claim 21 A secondary battery according to claim 1, wherein the first convex portion and the second convex portion are formed on a surface facing the outside of the case, and the connecting notch and the side notch are formed on a surface facing the inside of the case. Claim 22 A secondary battery according to claim 1, wherein the first convex portion and the second convex portion are formed on a surface facing the inside of the case, and the connecting notch and the side notch are formed on a surface facing the outside of the case. Claim 23 A secondary battery according to claim 1, wherein either of the first convex portion and the second convex portion is formed on a surface facing the outside of the case, and the other is formed on a surface facing the inside of the case. Claim 24 A secondary battery according to claim 1, wherein the vent portion further includes a support rib that protrudes from the outside of the side notch and surrounds the side notch.

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