Secondary battery

Abstract

A secondary battery according to an aspect of the present invention may comprise: a case; an electrode assembly inserted into the case; a cap plate coupled to the case; and a vent part formed in the case or the cap plate, wherein the vent part may include a plurality of side notches and a connection notch connecting the side notches, and the connection notch may include at least one curve line consisting of curves.

Description

secondary battery

[0001] The present invention relates to a secondary battery capable of being charged and discharged.

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

[0003] Currently commercially available secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Among these, lithium secondary batteries are attracting attention for their advantages, including virtually no memory effect compared to nickel-based batteries, free charging and discharging, a very low self-discharge rate, and high energy density.

[0004] These lithium secondary batteries primarily use lithium oxide and carbon materials as the positive and negative electrode active materials, respectively. Furthermore, the lithium secondary battery comprises a positive electrode plate and a negative electrode plate coated with the positive and negative electrode active materials, an electrode assembly in which the positive and negative electrode plates are positioned with a separator between them, and an outer case that seals and houses the electrode assembly together with an electrolyte.

[0005] Meanwhile, lithium secondary batteries can be classified into can-type secondary batteries, in which the electrode assembly is housed in a metal can, and pouch-type secondary batteries, in which the electrode assembly is housed in a pouch made of aluminum laminate sheet, depending on the shape of the battery case. Can-type secondary batteries can be further classified into cylindrical batteries and square batteries, depending on the shape of the metal can.

[0006] In the case of a square battery, a vent part is provided that opens as the internal pressure increases. The safety of the secondary battery can be increased if the vent part opens precisely at a preset pressure.

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

[0008] A secondary battery according to one aspect of the present invention includes a case, an electrode assembly inserted into the case, a cap plate coupled to the case, and a vent formed in the case or the cap plate, wherein the vent includes a plurality of side notches and a connecting notch connecting the side notches, and the connecting notch may include at least one curved line.

[0009] According to one aspect of the present invention, the curve line continues in an arc shape having a first radius of curvature, and at least one of the side notches may include a curved portion that is curved in an arc shape but has a second radius of curvature.

[0010] According to one aspect of the present invention, the connecting notch may be located on the concave inner side of the facing curved portion of the side notch.

[0011] According to one aspect of the present invention, the first radius of curvature may be larger than the second radius of curvature, and the first radius of curvature may be 1.1 to 5.5 times the second radius of curvature.

[0012] According to one aspect of the present invention, the side notch may include a first straight portion connected to one end of the curved portion and extending in a straight line, and a second straight portion connected to the other end of the curved portion and extending in a straight line.

[0013] The connecting notch according to one aspect of the present invention includes a first curve line and a second curve line, and the first curve line and the second curve line can protrude convexly in opposite directions.

[0014] According to one aspect of the present invention, the first curve line and the second curve line can be formed to have the same radius of curvature.

[0015] According to one aspect of the present invention, the connecting notch has an inflection point formed where the first curve line and the second curve line meet, and the tangent line at the inflection point is located at the center of the width direction of the vent part, and the acute angle of inclination at which it meets an imaginary reference line extending in the length direction of the vent part can be 5 to 60 degrees.

[0016] According to one aspect of the present invention, the first distance, which is the maximum distance from the connecting notch on a virtual reference line extending in the longitudinal direction of the vent portion, may be 0.05 to 0.4 times the second distance, which is the maximum distance from the side notch on the virtual reference line.

[0017] According to one aspect of the present invention, the vent portion includes two side notches, and the two side notches can be formed to surround the connecting notch by 50% to 90%.

[0018] According to one aspect of the present invention, the vent portion includes a base having a first side and a second side opposite to the first side, and the connecting notch and the side notch can be formed on the first side or the second side.

[0019] According to one aspect of the present invention, the vent portion includes a first linear protrusion convexly protruding from the first side of the base and a first linear groove concavely recessed from the second side of the base, wherein the first linear protrusion and the first linear groove each extend along the connecting notch, and the connecting notch can be formed in the first linear protrusion or the first linear groove.

[0020] According to one aspect of the present invention, the vent portion includes a first groove portion surrounding the side notches and the connecting notch and a second groove portion located at the bottom of the first groove portion and extending in the longitudinal direction of the connecting notch, wherein the side notches may be located in the first groove portion and the connecting notch may be located in the second groove portion.

[0021] According to one aspect of the present invention, the vent portion may be located on at least one of the cap plate, the bottom of the case, and the side of the case.

[0022] According to one aspect of the present invention, the curve line may be formed as a curve having a plurality of radii of curvature.

[0023] According to one aspect of the present invention, the vent portion includes a first convex portion and a second convex portion that are arranged adjacent to each other and have the connecting notch positioned therebetween, and the first convex portion and the second convex portion may extend between the connecting notch and any one of the plurality of side notches and protrude from the base.

[0024] According to one aspect of the present invention, both the first convex portion and the second convex portion may protrude from the base toward the first side or the second side, or each of the first convex portion and the second convex portion may protrude from the base toward the first side and the second side.

[0025] According to one aspect of the present invention, the longitudinal direction of the vent portion may be parallel to the longitudinal direction of the cap plate.

[0026] According to one aspect of the present invention, the longitudinal direction of the vent portion may extend in a direction intersecting the longitudinal direction of the cap plate.

[0027] According to a secondary battery according to one embodiment of the present invention, the connection notch includes at least one curved line, thereby efficiently and reliably relieving an increase in internal pressure of the case.

[0028] FIG. 1 is a perspective view illustrating a secondary battery according to a first embodiment of the present invention.

[0029] Figure 2 is a cross-sectional view taken along line II-II in Figure 1.

[0030] Figure 3 is a plan view from above of a secondary battery according to the first embodiment of the present invention.

[0031] Figure 4 is a plan view illustrating a vent section according to the first embodiment of the present invention.

[0032] Figure 5 is a cross-sectional view taken along line V-V in Figure 3.

[0033] FIG. 6 is a drawing partially illustrating a connection notch according to a first embodiment of the present invention.

[0034] Fig. 7 is a perspective view showing a vent section in an open state according to the first embodiment of the present invention.

[0035] Figure 8 is a perspective view illustrating a vent section according to a second embodiment of the present invention.

[0036] Fig. 9 is a cross-sectional view taken along line Ⅸ-Ⅸ in Fig. 8.

[0037] Fig. 10 is a cross-sectional view showing a vent part according to a third embodiment of the present invention.

[0038] Fig. 11 is a perspective view illustrating a vent section according to a fourth embodiment of the present invention.

[0039] Fig. 12 is a cross-sectional view taken along line ⅩⅡ-ⅩⅡ in Fig. 11.

[0040] Fig. 13 is a plan view illustrating a vent section according to the fifth embodiment of the present invention.

[0041] Fig. 14 is a perspective view illustrating a vent section according to the sixth embodiment of the present invention.

[0042] Fig. 15 is a cross-sectional view of the vent section of Fig. 14.

[0043] Figure 16 is a cross-sectional view taken along line A3-A3 in Figure 14.

[0044] Figure 17 is a cross-sectional view taken along line A4-A4 in Figure 14.

[0045] Figure 18 is a cross-sectional view taken along line A5-A5 in Figure 14.

[0046] Fig. 19 is a perspective view illustrating a vent section according to the seventh embodiment of the present invention.

[0047] Figure 20 is a cross-sectional view taken along line A6-A6 in Figure 19.

[0048] Fig. 21 is a perspective view from below of a vent section according to the eighth embodiment of the present invention.

[0049] Figure 22 is a cross-sectional view taken along line A7-A7 in Figure 21.

[0050] Fig. 23 is a cross-sectional view of a portion where a connecting notch and a first side notch are located in a vent section according to the ninth embodiment of the present invention.

[0051] Fig. 24 is a cross-sectional view showing a portion where a connecting notch and a second side notch are located in a vent section according to the ninth embodiment of the present invention.

[0052] Fig. 25 is a cross-sectional view of a portion where a connecting notch and a first side notch are located in a vent section according to the 10th embodiment of the present invention.

[0053] Fig. 26 is a cross-sectional view showing a portion where a connecting notch and a second side notch are located in a vent section according to the 10th embodiment of the present invention.

[0054] Fig. 27 is a perspective view illustrating a secondary battery according to the 11th embodiment of the present invention.

[0055] Fig. 28 is a drawing illustrating a vent protection film according to the 11th embodiment of the present invention.

[0056] Figure 29 is a cross-sectional view taken along line ⅩⅥ-ⅩⅥ in Figure 27.

[0057] Fig. 30 is a perspective view illustrating a secondary battery according to the 12th embodiment of the present invention.

[0058] Fig. 31 is a perspective view illustrating a secondary battery according to the 13th embodiment of the present invention.

[0059] Figure 32 is a plan view from above of a secondary battery according to the 14th embodiment of the present invention.

[0060] Figure 33 is a plan view illustrating the vent section of Figure 32.

[0061] Figure 34 is a plan view of a secondary battery according to the 15th embodiment of the present invention.

[0062] The present invention is susceptible to various modifications and embodiments. 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, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0063] The terminology used herein is merely used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In the present invention, it should be understood that the terms "comprise" or "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0064] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Please note that, where possible, identical components are represented by identical reference numerals throughout the drawings. Furthermore, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted.

[0065] Below, a secondary battery according to one embodiment of the present invention is described.

[0066] FIG. 1 is a perspective view showing a secondary battery according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1, and FIG. 3 is a plan view of the secondary battery according to the first embodiment of the present invention as seen from above.

[0067] Referring to FIGS. 1 to 3, a 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) accommodating 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).

[0068] The electrode assembly (10) performs charging and discharging, and can be formed in various forms such as an all-solid-state electrode assembly, a lithium-ion electrode assembly, and a sodium-ion electrode assembly.

[0069] The electrode assembly (10) includes an anode (11), a cathode (12), and a separator (13) interposed between the anode (11) and the cathode (12). The anode (11), the separator (13), and the cathode (12) may be formed in a laminated structure or in a structure wound in the form of a jelly roll.

[0070] In addition, the electrode assembly (10) may be configured in a structure in which a positive electrode (11) and a negative electrode (12) are alternately inserted between separators (13) bent in a zigzag shape. In addition, the electrode assembly (10) may be configured in various forms, such as an all-solid-state type without a separator. The separator may be a material such as an electrically non-conductive polymer or ceramic material that separates the positive electrode and the negative electrode 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-state type in which there is no separate separator and a solid electrolyte can perform the roles of both the electrolyte and the separator.

[0071] In this embodiment, the z-axis direction (or vertical direction) may mean, for example, a direction perpendicular to the cap or cap plate (21) (or the corresponding opening in the case (30)). That is, a direction perpendicular to a surface of the cap or cap plate (21), particularly a main surface. The x-axis and y-axis directions (or horizontal directions or horizontal planes) may mean, for example, directions parallel to the cap or cap plate (21) (for example, a direction parallel to the surface of the cap or cap plate (21), particularly a main surface), and an opening in the case (30). The x-axis direction and the y-axis direction may be positioned, for example, along the smallest horizontal expansion direction and the largest horizontal expansion direction of the case (30), respectively.

[0072] With respect to the case (30), the direction perpendicular to the opening of the case (30) (z-axis direction) of the cap or cap plate (21) may be referred to as the longitudinal direction of the case (30). The smallest expansion direction of the case (30) in a plane perpendicular to the longitudinal direction may also be referred to as the thickness direction of the case (30), which may coincide with the x-axis direction. The largest expansion direction of the case (30) in a plane perpendicular to the longitudinal direction 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.

[0073] With respect to other configurations (e.g., parts, structures, elements, etc.), and particularly configurations that may have a planar or substantially planar shape (e.g., cap plate (21) and vent portion (50)), the greatest 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., the direction perpendicular to the main plane of the object) may be referred to as the thickness direction of the configuration. The smallest extension direction of the configuration in a plane perpendicular to the thickness direction (lateral extension) may be referred to as the width direction (or lateral direction) of the configuration.

[0074] The positive electrode (11) and the negative electrode (12) may include a coated portion, which is a region 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 a side end of the positive electrode (11), and the negative electrode non-coated portion (16) may protrude from a 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).

[0075] The positive electrode non-coated portion (15) and the negative electrode non-coated portion (16) are formed in the form 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 by notching. In addition, the tabs can be a member separately coupled to the electrodes. The positive electrode non-coated portions (15) and the negative electrode non-coated portions (16) can be stacked in the thickness direction (x-axis direction) of the case (30).

[0076] In addition, the positive electrode non-conductive part (15) can be connected to the first terminal (23) via a current collecting member (41), and the negative electrode non-conductive part (16) can be connected to the second terminal (24) via a current collecting member (42).

[0077] 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 composed 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).

[0078] 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 a square shape or a cylindrical shape. One electrode assembly (10) or multiple electrode assemblies (10) may be inserted into the case (30).

[0079] The case (30) may have a prism shape (i.e., at least substantially prism-shaped), and in particular may have a square (quadrilateral) prism shape, such as a rectangular cuboid shape (i.e., at least substantially rectangular cuboid shape). Alternatively, the case and / or the housing may have a cylindrical shape, for example. The case (30) may be formed with an opening, for example, for inserting an electrode assembly into the case (30). The opening may be formed in at least one side of the case (e.g., the surface, the top side, or the surface). In some examples, the opening may extend across the entire side of the case (e.g., the entire top or top surface).

[0080] An electrolyte can be accommodated together with an electrode assembly (10) inside the case (100). The electrolyte can be in the form of a liquid, solid, or gel.

[0081] 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.

[0082] An electrolyte injection port (H1) for injecting electrolyte and a vent hole (H2) in which a vent part (50) is installed may be formed in the cap plate (21). A sealing plug (28) that blocks the electrolyte injection port (H1) may be installed in the electrolyte injection port (H1), and a vent part (50) that opens at a preset pressure may be formed in the vent hole (H2).

[0083] An upper insulating member (29) may be placed at the bottom 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 in the longitudinal direction (y-axis direction) of the cap plate (21).

[0084] Terminals (23, 24) are connected 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 configured as a positive terminal, and the second terminal (24) may be configured as a negative terminal. When one terminal is installed on the cap plate (21), the case (30) may be charged negatively.

[0085] The first terminal (23) and the second terminal (24) may be formed in a plate shape. Any shape that allows effective electrical connection to an external load may be used for the first terminal (23) and the second terminal (24), including but not limited to a rod, a tube, a stud, a post, a button, or a pin, and the first terminal (23) and the second terminal (24) may be bent or straight. A gasket (25) for insulation may be installed between the first terminal (23) and the cap plate (21), and a gasket (26) for insulation may also be installed between the second terminal (24) and the cap plate (21). In addition, the gaskets (25, 26) may be connected downward and positioned between the current collecting member (41, 42) and the cap plate (21). The gaskets (25, 26) may be formed as a single member or may be divided into multiple members.

[0086] The first terminal (23) is electrically connected to the positive electrode non-conducting portion (15) via the first current collecting member (41), and the second terminal (24) can be electrically connected to the negative electrode non-conducting portion (16) via the second current collecting member (42).

[0087] The first terminal (23) and the second terminal (24) are formed in a plate shape, and a hole into which a connecting pillar of the first current collecting member (41) or the second current collecting member (42) is inserted can be formed in the center of the first terminal (23) and the second terminal (24).

[0088] The electrode assembly (10) may include two positive electrode non-polar arrays having the same polarity, and the positive electrode non-polar 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 positive electrode non-polar array may be welded to the first current collecting member (41).

[0089] Additionally, the electrode assembly (10) may include two negative electrode non-conductive arrays having the same polarity, and the negative electrode non-conductive 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-conductive array may be welded to the first current collecting member (41).

[0090] FIG. 4 is a plan view illustrating a vent part according to a first embodiment of the present invention, FIG. 5 is a cross-sectional view taken along line V-V in FIG. 3, FIG. 6 is a drawing partially illustrating a connection notch according to the first embodiment of the present invention, and FIG. 7 is a perspective view illustrating a vent part according to the first embodiment of the present invention in an open state.

[0091] Referring to FIGS. 4 to 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 oval 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 and / or straight sides, such as a square, rectangle, polygon, or circle, may also be applied.

[0092] The vent portion (50) may extend in the longitudinal direction (y-axis direction) of the cap plate (21). The vent portion (50) may have a longitudinal major axis direction and a widthwise minor axis direction, and the major axis direction may extend parallel to the longitudinal direction (y-axis direction) of the cap plate (21).

[0093] 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 that firmly fixes 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 sandwiched between the upper and lower portions of the cap plate (21) to fix the vent portion (50) to the cap plate (21).

[0094] 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) are formed as long 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 and arcs.

[0095] The vent portion (50) may form a weakened portion compared to adjacent or surrounding portions to form a connecting notch (51) and side notches (52, 53). The connecting notch (51) and side notches (52, 53) may be a notch shape having a groove shape on the surface of the vent material, or the connecting notch (51) and side notches (52, 53) may be formed by weakening the vent material, such as by chemical, thermal, compression, or radiation. The connecting notch (51) and side notches (52, 53) may be configured to be easily broken when a predetermined specific breaking pressure is reached within the secondary battery. The pressure may be a pressure difference between the inside and the outside of the secondary battery (100), and may be caused, for example, by gas formation within the secondary battery or expansion of the electrolyte and / or electrode assembly (10).

[0096] The notches (51, 52, 53) may be intentionally introduced weak lines or areas and may be configured to fracture (e.g., bend and / or burst, open, fold, and / or otherwise deform) at a predetermined specific fracture pressure. This allows the vent structure to be opened. Each of the notches (51, 52, 53) may be, for example, a structurally weakened portion of the vent structure, which may be formed, for example, by removal and / or deformation of material. The notches may be formed in the base of the vent portion (e.g., a substrate such as a plate or slab), as described below.

[0097] Additionally, the connecting notch (51) and the side notches (52, 53) can be broken at a preset pressure. As shown in Fig. 5, a base groove (55) is formed in the vent portion (50), and the connecting notch (51) and the side notches (52, 53) can be formed at the bottom of the base groove (55).

[0098] The vent portion (50) may be configured to seal, for example, 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., the 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 escape from within the secondary battery when opened.

[0099] In the present 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), and the first side represents an upper side of the base, i.e., an outer side facing the outside of the secondary battery, and the second side represents a lower side of the base, i.e., an inner side facing the inside of the secondary battery.

[0100] At this time, the connecting notch (51) and the side notch (52, 53) may be formed on the first side of the base, i.e., 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, i.e., the lower side of the base.

[0101] The connecting notch (51) may include a first curve line (51a) and a second curve line (51b) formed in a curved shape. 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.

[0102] The first curve line (51a) may protrude convexly toward one side end of the vent part (50) (in the -x-axis direction), and the second curve line (51b) may protrude convexly toward the other side end of the vent part (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.

[0103] Here, the inflection point (CP1) where the first curve line (51a) and the second curve line (51b) meet can be formed at the longitudinal center of the connecting notch (51). In addition, 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 the first radius of curvature (R11). Accordingly, the connecting notch (51) can be formed point-symmetrically with respect to the inflection point (CP1).

[0104] The connecting notch (51) may be connected to, for example, the two side notches (52 53) at an angle (e.g., they may meet or intersect), wherein the angle (e.g., the smallest angle formed between each fracture line) may be, for example, between 20° and 90°, for example, greater than or equal to 45° or 60° and / or less than or equal to 90°, 80° or 70°. The two side notches (52 53) may be spatially separated from each other (e.g., not directly connected only by the connecting notch (51) (indirectly)) or alternatively may be connected to each other, for example, forming part of a single fracture line.

[0105] Meanwhile, the two side notches (52, 53) are formed convexly in opposite directions, but may protrude convexly toward the longitudinal outer side 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) may have the same structure and be arranged symmetrically.

[0106] The first side notch (52) may include a curved portion (52a) that is curved in an arc shape, a first straight portion (52b) that is connected to one end of the curved portion (52a) and is connected in a straight line, and a second straight portion (52c) that is connected to the other end of the curved portion (52a) and is connected in a straight line.

[0107] The first straight portion (52b) and the second straight portion (52c) extend in the longitudinal direction (y-axis direction) of the cap plate (21) and can be arranged parallel to each other. The curved portion (52a) is formed as an arc having a second radius of curvature (R12) and is formed to partially surround the connecting notch (51).

[0108] In addition, the second side notch (53) may include a curved portion (53a) that is curved in an arc shape, a first straight portion (53b) that is connected to one end of the curved portion (53a) and is connected in a straight line, and a second straight portion (53c) that is connected to the other end of the curved portion (53a) and is connected in a straight line. In addition, the connecting notch (51) may be connected to the longitudinal central portions of the first side notch (52) and the second side notch (53).

[0109] The side notches (52, 53) may surround 25% to 100%, preferably 50% to 90%, and in one example 60% to 80% of the length of the connecting notch (51) (i.e., surround the connecting notch (51) along that portion of its length). The length of the connecting notch (51) is, for example, the distance between the two points on the connecting notch (51) that are furthest from each other and / or the length of the (curved) path along which the connecting notch (51) extends. A connecting notch (51) may be considered to be "surrounded" by two side notches (52, 53) if the side notches (52, 53) are arranged on either side of the connecting notch (51) (e.g., in a direction perpendicular to the connecting notch (51)).

[0110] The first side notch (52) and the second side notch (53) are spaced apart from each other and may be formed to partially surround the connecting notch (51). Here, the first side notch (52) and the second side notch (53) may surround the connecting notch (51) by 50% to 90%.

[0111] One or both of the first straight portion (52b) and the second straight portion (52c) may be smoothly connected to the curved portion (i.e., without twisting or sharp bending), for example, connected tangentially to the corresponding end of the curved portion. One or both of the first straight portion (52b) and the second straight portion (52c) may extend parallel or substantially parallel to the greatest extension direction (longitudinal direction) of the vent portion (50) and / or the greatest extension direction (longitudinal direction) of the side surface of the cap or case on which the vent structure is formed. The first straight portion (52b) and the second straight portion (52c) may be parallel or substantially parallel to each other. One or more of the side notches (52, 53) may have a U-shape (the curved portion connects two straight legs / linear portions). As described herein, two directions or elements being substantially parallel means that each direction and element is positioned at an angle (e.g., extended or projected) of between -20° and 20° with respect to the other, and in some examples between -10° and 10°, in one example between -5° and 5°, and in one example between -2° and 2°.

[0112] The first gap (G11), which is the maximum gap between the connecting notch (51) and the virtual reference line (SL1) located at the center portion in the width direction (x-axis direction) of the vent part (50) and extending in the length direction (y-axis direction) of the vent part (50), may be 0.05 to 0.4 times the second gap (G12), which is the maximum gap between the first side notch (52) and the virtual reference line (SL1).

[0113] Meanwhile, as illustrated in Fig. 6, the acute angle (A11) at which the tangent line (SL2) at the inflection point (CP1) meets the virtual reference line (SL1) may be 5 to 60 degrees. Preferably, the acute angle (A11) may be 10 to 30 degrees.

[0114] The first radius of curvature (R11) and the second radius of curvature (R12) are formed differently, and the first radius of curvature (R11) can be formed larger than the second radius of curvature (R12). The first radius of curvature (R11) can be formed to be 1.1 to 5.5 times the second radius of curvature (R12), and further, the first radius of curvature (R11) can be formed to be 1.8 to 2.2 times the second radius of curvature (R12).

[0115] When 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) continues as a gentle curve, so that when the connecting notch (51) breaks, the connecting notch can be easily broken along the curve.

[0116] In addition, if the first radius of curvature (R11) is formed smaller than the second radius of curvature (R12), there is a problem in that the height deviation of the bent pieces (50a, 50b) that are broken and folded is formed too large, as shown in Fig. 7. If the height deviation of the bent pieces (50a, 50b) is large, there is a problem in that the high part touches the upper structure and cannot be opened properly, or there is a problem in that a lot of space must be secured at the top.

[0117] When the connecting notch (51) is connected in an S-shaped curve, the pressure-bearing area increases compared to a straight line, enabling accurate and easy breaking at a preset breaking pressure. Furthermore, when the connecting notch (51) breaks, it can easily and quickly break along the curve. By enabling easy and quick breaking along the curve, the connecting notch can initiate the opening of the vent portion.

[0118] In addition, in the side notches (52, 53), the curved portion (52a) can be broken and 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 pieces (50a, 50b) can be easily bent to quickly secure a discharge space. In addition, 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). In addition, the side notches (52, 53) can minimize obstruction or interference from the vent pieces (50a, 50b) during gas discharge.

[0119] Meanwhile, in some cases, the connecting notch (51) may not be broken and the side notches (52, 53) may be broken first. In this case, the curved portion (52a), the first straight portion (52b), and the second straight portion (52c) are all broken, forming two openings on both sides, thereby securing sufficient space for gas discharge.

[0120] Below, a secondary battery according to a second embodiment of the present invention is described.

[0121] Fig. 8 is a perspective view showing a vent part according to a second embodiment of the present invention, and Fig. 9 is a cross-sectional view taken along line Ⅸ-Ⅸ in Fig. 8.

[0122] Referring to FIGS. 8 and 9, 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 part (210), so a duplicate description of the same configuration is omitted.

[0123] The vent portion (210) may include two side notches (212, 213) and a connecting notch (211) connecting the side notches (212, 213).

[0124] In addition, the vent portion (210) may include a first linear protrusion (215) that extends in the longitudinal direction of the connecting notch (211) and protrudes convexly, and a second linear protrusion (216) that extends in the longitudinal direction of the side notches (212, 213) and protrudes convexly. The vent portion (210) includes two second linear protrusions (216), and the second linear protrusions (216) may be connected to the first linear protrusion (215). In addition, a first linear groove portion (214) may be formed on an opposite surface of the first linear protrusion portion (215), and a second linear groove portion (217) may be formed on an opposite surface of the second linear protrusion portion (216).

[0125] The first linear protrusion (215) and the second linear protrusion (216) may be convexly protruded from the surface of the vent portion (210). The first linear protrusion (215) and the second linear protrusion (216) may be formed, for example, as raised portions protruding from the surface of the vent portion (210). The first linear protrusion (215) and the second linear protrusion (216) may have a constant top height along the longitudinal direction. The first linear protrusion (215) and the second linear protrusion (216) may have varying top heights along the longitudinal direction. The heights or maximum heights or minimum heights of the first linear protrusion (215) and the second linear protrusion (216) may be the same or different.

[0126] A connecting notch (211) is formed in the first linear protrusion (215) and may be located at the uppermost part of the first linear protrusion (215). The connecting notch (211) may be located along the first linear protrusion (215) at a height other than the highest part of the first linear protrusion (215). A part of the connecting notch (211) may be located at the uppermost part of the linear protrusion (215), and a part of the connecting notch (211) may be located along the first linear protrusion (215) at a height other than the highest part of the first linear protrusion (215). In addition, side notches (212, 213) are formed in the second linear protrusion (216) and may be located at the uppermost part of the second linear protrusion (216). The side notches (212, 213) may also be positioned along the second linear protrusion (216) at a height other than the highest portion of the linear protrusion (216). A portion of either or both of the side notches (212, 213) may be positioned at the uppermost portion of the second linear protrusion (216), and a portion of either or both of the side notches (212, 213) may be positioned along the second linear protrusion (216) at a height other than the highest portion of the second linear protrusion (216). The longitudinal cross sections of the first linear protrusion (215) and the second linear protrusion (216) may be formed in an arc shape or a triangle shape.

[0127] The width of the first linear protrusion (215) or the second linear protrusion (216) (e.g., perpendicular to the longitudinal direction in which the protrusion mainly extends) may be equal to or greater than the width of the connecting notch (510) (e.g., 1.5 to 20 times, and in some examples, 2.0 to 10 times, the width of the connecting notch (51). In particular, when the connecting notch (51) is implemented as a notch. In an example in which the connecting notch (51) is implemented as a notch, the depth of the notch may be less than or equal to the height (e.g., in the direction perpendicular to the bottom surface of the vent and / or in the thickness direction of the vent) of the first linear protrusion (215) or the second linear protrusion (216), for example, 0.05 to 0.9 times, and in some examples, 0.1 to 0.5 times.

[0128] When the first linear protrusion (215) and the second linear protrusion (216) are formed as in the second embodiment, the connecting notch (211) and the side notches (212, 213) can be easily broken.

[0129] Below, a secondary battery according to a third embodiment of the present invention is described.

[0130] Fig. 10 is a cross-sectional view showing a vent part according to a third embodiment of the present invention.

[0131] Referring to FIG. 10, 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 part (220), so a duplicate description of the same configuration is omitted.

[0132] The vent portion (220) may include two side notches (222) and a connecting notch (221) connecting the side notches (222). In addition, the vent portion (220) may include a first linear protrusion (225) extending in the longitudinal direction of the connecting notch (221) and protruding convexly, and a second linear protrusion (226) extending in the longitudinal direction of the side notch (222) and protruding convexly.

[0133] The vent portion (220) includes two second linear protrusions (226), and the second linear protrusions (226) can be connected to the first linear protrusion (225). A first linear groove portion (224) can be formed on the opposite surface of the first linear protrusion portion (225), and a second linear groove portion (227) can be formed on the opposite surface of the second linear protrusion portion (226).

[0134] The first linear groove (224) and the second linear groove (227) may be formed on a surface of the vent (220) facing the inside of the case. The first linear groove (224) may extend in the longitudinal direction of the connecting notch (221) and may have a concavely sunken structure. The second linear groove (227) may extend in the longitudinal direction of the side notch (222) and may have a concavely sunken structure.

[0135] The connecting notch (221) may be located at the bottom of the first linear groove portion (224), and the side notch (222) may be located at the bottom of the second linear groove portion (227). Accordingly, the connecting notch (221) and the side notch (222) are also formed on the surface of the vent portion (220) facing the inside of the case.

[0136] Below, a secondary battery according to a fourth embodiment of the present invention is described.

[0137] Fig. 11 is a perspective view showing a vent part according to the fourth embodiment of the present invention, and Fig. 12 is a cross-sectional view taken along line ⅩⅡ-ⅩⅡ in Fig. 19.

[0138] Referring to FIGS. 19 and 20, 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 part, so a duplicate description of the same configuration is omitted.

[0139] The vent portion (230) may include two side notches (232, 233) and a connecting notch (231) connecting the side notches (232, 233). In addition, the vent portion (230) may include a first groove portion (234) surrounding the side notches (232, 233) and the connecting notch (231) and a second groove portion (237) extending in the longitudinal direction of the connecting notch (231).

[0140] The first groove (234) is located on the lower surface of the vent (230), and the side notches (232, 233) can be located in the first groove (234). The first groove (234) can have a cross-section in the shape of a track in which two semicircles are connected by two straight lines.

[0141] Meanwhile, the second groove (237) is formed by being sunken into the bottom of the first groove (234), and the connecting notch (231) can be located in the second groove (237). The second groove (237) extends in the longitudinal direction of the connecting notch (231) and can be formed to surround the connecting notch (231).

[0142] Meanwhile, a first protrusion (235) may be formed on the opposite surface of the first groove (234), and a second protrusion (236) may be formed on the opposite surface of the second groove (237). The second protrusion (236) may be positioned on the first protrusion (235).

[0143] As in the fourth embodiment, when a second groove (237) is formed at the bottom of the first groove (234) and the connecting notch (231) is positioned at the second groove (237), pressure is concentrated on the connecting notch (231), so that the connecting notch (231) can be easily broken.

[0144] Below, a secondary battery according to a fifth embodiment of the present invention is described.

[0145] Fig. 13 is a plan view illustrating a vent section according to the fifth embodiment of the present invention.

[0146] Referring to FIG. 13, 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 part (240), so a duplicate description of the same configuration is omitted.

[0147] 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 curved line (241a) and a second curved line (241b) formed in a curved shape. The first curved line (241a) and the second curved line (241b) may be formed in an arc shape and may protrude convexly in different directions. For example, a line protruding in one direction may be bent like a bow in the direction in which the line protrudes to form a bulge of the line.

[0148] The first curve line (241a) may protrude convexly toward one side end of the vent part (240), and the second curve line (241b) may protrude convexly toward the other side end of the vent part (240). The first curve line (241a) and the second curve line (241b) may have the same shape, but may protrude convexly in opposite directions.

[0149] 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 portion (241aa) having a first radius of curvature (R21), a second portion (241ab) connected to one longitudinal end of the first portion (241aa) and having a second radius of curvature (R22), and a third portion (241ac) connected to the other longitudinal end of the first portion (241aa) and having a third radius of curvature (R23). The first radius of curvature (R21) may be formed to be larger than the second radius of curvature (R22), and the first radius of curvature (R21) may be formed to 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.

[0150] Alternatively, the first radius of curvature (R21) may be greater than one or both of the second radius of curvature (R22) and the third radius of curvature (R23), for example at least 10% greater, in some examples at least 25% greater, in one example at least 50% greater, or in one example at least 100% greater.

[0151] Meanwhile, the second curve line (241b) may be formed as a curve having multiple radii of curvature. The second curve line (241b) may include a first portion (241ba), a second portion (241bb) connected to one longitudinal end of the first portion (241ba), and a third portion (241bc) connected to the other longitudinal end of the first portion (241ba).

[0152] The radius of curvature of the first part (241ba) is formed to be larger than the radii 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.

[0153] The two side notches (242, 243) may be convexly protruded in opposite directions and may include a curved portion connected in an arc shape. The two side notches (242, 243) may be spaced apart from each other and formed to partially surround the connecting notch (241). The curved portion of the side notches (242, 243) may have a fourth radius of curvature (R24).

[0154] 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 formed to be 0.3 to 0.7 times the second radius of curvature (R22).

[0155] As in the fifth embodiment, when the first curve line (241a) and the second curve line (241b) have multiple curvature radii, the design freedom of the connecting notch (241) increases further, and the connecting notch (241) can be easily broken under more precise pressure. As the length of the connecting notch increases, the area subject to pressure also increases due to the increased notch length compared to the case where the connecting notch has a single curvature radius, so that venting can occur more easily.

[0156]

[0157] Below, a secondary battery according to the sixth embodiment of the present invention is described.

[0158] Fig. 14 is a perspective view showing a vent part according to the sixth embodiment of the present invention, and Fig. 15 is a cross-sectional view of the vent part of Fig. 14.

[0159] Referring to FIGS. 14 and 15, 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 part, so a duplicate description of the same configuration is omitted.

[0160] Referring to FIGS. 14 and 15, the vent portion (50) may include a first convex portion (56) and a second convex portion (57) formed between the connecting notch (51) and the side notches (52, 53). The first convex portion (56) may be positioned between one side end of the connecting notch (51) and the side notches (52, 53), and the second convex portion (57) may be positioned between one side 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 portions can be formed by two connecting notches spaced apart from each other, and four convex portions can be formed by connecting notches having three curved lines spaced apart from each other.

[0161] 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., the plane is a plane on which the notches on which the first convex portion (56) and the second convex portion (57) are arranged are located). Alternatively, 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., out of the plane of the vent portion or the bottom). The first convex portion (56) and the second convex portion (57) may protrude outwardly (away from the interior of the case) or inwardly (toward the interior of the case). The first convex portion (56) and the second convex portion (57) can be continuously bent along 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 inverse of the bending radius) or the bending angle or inclination (e.g., with respect 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 the bending angle / inclination of the first and second concave portions, respectively, and in some examples may be substantially smaller (e.g., at least twice smaller, in some examples at least three times smaller, in one example at least five times smaller, and in another example at least ten times smaller).

[0162] The first convex portion (56) and the second convex portion (57) may be arranged adjacently and spaced apart from each other with a connecting notch (51) therebetween. For example, the first convex portion (56) may be arranged on the left side of the connecting notch (51), and the second convex portion (57) may be arranged on the right side of the connecting notch (51).

[0163] A support plate (58) made of a flat plate and inserted between the cap plate (21) and the upper insulating member (29) can be formed on the outer side of the first convex portion (56) and the second convex portion (57).

[0164] The first convex portion (56) and the second convex portion (57) can extend from the portion where the connecting notch (51) and the first side notch (52) are connected to the portion where the connecting notch (51) and the second side notch (53) are connected. A concave portion can be formed on the opposite surface of the first convex portion (56) and the second convex portion (57).

[0165] Both the first convex portion (56) and the second convex portion (57) may protrude toward the upper surface 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 surface of the base, i.e., the second side. Alternatively, the first convex portion (56) may protrude toward the upper surface of the base, and the second convex portion (57) may protrude toward the lower surface of the base.

[0166] 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 larger than the height of the second convex portion (57) (for example, at least 2% larger, in some examples at least 10% larger, and in some examples at least 20% larger). For example, the height of the first convex portion (56) may be 1.02 to 2.5 times larger than the height of the second convex portion (57).

[0167] Accordingly, the first distance (D11) between the upper end of the first convex portion (56) and the inner end of the vent member (50) may be formed to be greater than the second distance (D12) between the upper end of the second convex portion (57) and the inner end of the vent member (50). The first distance (D11) may be formed to 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 may be more easily broken due to an imbalance in force.

[0168]

[0169] Fig. 16 is a cross-sectional view taken along line A3-A3 in Fig. 14, Fig. 17 is a cross-sectional view taken along line A4-A4 in Fig. 14, and Fig. 18 is a cross-sectional view taken along line A5-A5 in Fig. 14.

[0170] Referring to FIGS. 14, 16, and 18, the connecting notch (51) may include an inflection point (CP1) where the first curve line (51a) and the 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 another variation, additional curve lines that meet at midpoints instead of the 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 120 degrees apart from each other (of course, other angles may also be used). As another example, four curved lines may be arranged to meet at a midpoint, and the ends of the four curved lines may be spaced 90 degrees apart (although other angles may also be used). In another embodiment, the curved lines forming the connecting notch may be of equal length, or one or more may have different lengths.

[0171] In addition, the first inclination angle (K21) formed by the tangent line of the widthwise outer end of the first convex portion (56) of the vent portion (50) at the first reference point (CP2) and the imaginary reference plane (SF1) parallel to the cap plate (21) and the second inclination angle (K22) formed by the tangent line of the widthwise outer end of the first convex portion (56) at the second reference point (CP3) and the reference plane (SF1) can be formed to be greater than the third inclination angle (K23) formed by the tangent line of the widthwise outer end of the first convex portion (56) at the inflection point (CP1) and the reference plane (SF1).

[0172] Here, the outer end of the first convex portion (56) in the width direction 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) from the first reference point (CP2), the second reference point (CP3), or the inflection point (CP1).

[0173] Additionally, the first inclination angle (K21) and the second inclination angle (K22) may be 1.2 to 2.5 times the third inclination angle (K23).

[0174] 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.

[0175] When the first inclination angle (K21) and the second inclination angle (K22) are formed to be greater than the third inclination angle (K23), when the inclination angle is swelled in the center, uniform deformation of the center and the side is induced, so that the notch can be easily broken. In particular, when 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 part (50) can be controlled more precisely. Alternatively, the third inclination angle (K23) may be at least 10% smaller than the first inclination angle (K21) and the second inclination angle (K22), or in some examples, at least 20% smaller, or in some examples, at least 30% smaller.

[0176] According to this embodiment, a first convex portion (56) and a second convex portion (57) are formed, and the heights of the first convex portion (56) and the second convex portion (57) are formed differently, so that the notch can be easily and safely broken at a preset pressure.

[0177] When the connecting notch (51) is connected in an S-shaped curve, the area under pressure increases compared to a straight line, so that it can be accurately and easily broken at a preset breaking pressure. In addition, when the connecting notch (51) is broken, it can be easily and quickly broken along the curve.

[0178] In addition, in the side notches (52, 53), the curved portion (52a) can be broken, and 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. In addition, the first straight portion (52b) and the second straight portion (52c) may be partially or completely broken depending on the breaking environment.

[0179] Meanwhile, in some cases, the connecting notch (51) may not be broken and the side notches (52, 53) may be broken first. In this case, the curved portion (52a), the first straight portion (52b), and the second straight portion (52c) are all broken, forming two openings on both sides, thereby securing sufficient space for gas discharge.

[0180]

[0181] Below, a secondary battery according to the seventh embodiment of the present invention is described.

[0182] Fig. 19 is a perspective view showing a vent part according to the seventh embodiment of the present invention, and Fig. 20 is a cross-sectional view taken along line A6-A6 in Fig. 19.

[0183] Referring to FIGS. 19 and 20, the secondary battery according to the seventh embodiment has the same structure as the secondary battery according to the sixth embodiment described above except for the vent part (150), so a duplicate description of the same configuration is omitted.

[0184] 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 an outer surface of the vent portion (150) facing the outside of the case.

[0185] The connecting notch (151) and side notch (152, 153) according to the seventh embodiment have the same structure as the connecting notch and side notch of the sixth embodiment described above.

[0186] Additionally, the vent portion (150) may further include a first support rib (154) positioned on the outside of the first side notch (152) and surrounding the first side notch (152), and a second support rib (155) positioned on the outside of the second side notch (153) and surrounding the second side notch (153).

[0187] 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 upper end 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).

[0188] The first support rib (154) can prevent deformation of the vent portion (150) and can play a supporting role so that the first side notch (152) can be easily torn when the first side notch (152) is broken.

[0189] In addition, 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 upper end of the second side notch (153), but the present invention is not limited thereto. The second support rib (155) may prevent deformation of the vent portion (150) and may play a supporting role so that the second side notch (153) can be easily torn when the second side notch (153) is broken.

[0190] 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 positioned between one side end of the connecting notch (151) and the side notches (152, 153), and the second convex portion (157) may be positioned between one side end of the connecting notch (151) and the side notches (152, 153). For example, the first convex portion (156) may be positioned on the left side of the connecting notch (151), and the second convex portion (157) may be positioned on the right side of the connecting notch (151).

[0191] The first convex portion (156) and the second convex portion (157) can 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) can be formed on the opposite surface of the first convex portion (156), and a second concave portion (159) can be formed on the opposite surface of the second convex portion (157).

[0192] The connecting notch (151) may be located in the valley portion (VL1) formed between the first convex portion (156) and the second convex portion (157). The 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 the 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).

[0193] The first tangential angle (K31) formed by the tangent line at the end adjacent to the connecting notch (151) in the first convex portion (156) and the imaginary reference plane (SF1) parallel to the cap plate (21) may be formed smaller than the second tangential angle (K32) formed by the tangent line at the end adjacent to the first side notch (152) or the second side notch (153) in the first convex portion (156) and the reference plane (SF1).

[0194] The first tangential angle (K31) can be from 1 to 20 degrees, and the second tangential angle (K32) can be from 2 to 30 degrees. In addition, the first tangential angle (K31) can be from 2 to 15 degrees, and the second tangential angle (K32) can be from 2 to 25 degrees.

[0195] The second tangent angle (K32) may 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) may be 1 to 10 degrees.

[0196] The third tangent angle (K33) formed by the tangent line at the end adjacent to the connecting notch (151) in the second convex portion (157) and the imaginary reference plane (SF1) parallel to the cap plate (21) may be formed smaller than the fourth tangent angle (K34) formed by the tangent line at the end adjacent to the first side notch (152) or the second side notch (153) in the second convex portion (157) and the reference plane (SF1).

[0197] The fourth tangent angle (K34) can 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) can be 1 to 10 degrees.

[0198] The third tangential angle (K33) can be from 1 to 20 degrees, and the fourth tangential angle (K34) can be from 2 to 30 degrees. In addition, the third tangential angle (K33) can be from 2 to 15 degrees, and the fourth tangential angle (K35) can be from 2 to 25 degrees.

[0199] As described above, according to the seventh embodiment, the first support rib (154) and the second support rib (155) are formed, so that deformation of the vent portion (150) is prevented, and the side notches (152, 153) can be easily torn.

[0200] In addition, since the tangential angle of the portion connected to the connecting notch (151) in the first convex portion (156) and the second convex portion (157) is formed smaller than the tangential angle of the portion connected to the side notch (152, 153) in the first convex portion (156) and the second convex portion (157), not only can the connecting notch (151) placed in the center be easily elevated and deformed by pressure, but also the connecting notch (151) and the side notch (152, 153) can be easily broken.

[0201]

[0202] Below, a secondary battery according to the eighth embodiment of the present invention is described.

[0203] Fig. 21 is a perspective view of a vent section according to the eighth embodiment of the present invention as viewed from below, and Fig. 22 is a cross-sectional view taken along line A7-A7 in Fig. 21.

[0204] Referring to FIGS. 21 and 22, the secondary battery according to the eighth embodiment has the same structure as the secondary battery according to the sixth embodiment described above except for the vent part (160), so a duplicate description of the same configuration is omitted.

[0205] 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 eighth embodiment have the same structure as the connecting notch and the side notch of the sixth embodiment described above.

[0206] Additionally, the vent portion (160) may further include a first support rib (164) positioned on the outside of the first side notch (162) and surrounding the first side notch (162), and a second support rib (165) positioned 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.

[0207] 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).

[0208] 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.

[0209] The first convex portion (166) and the second convex portion (167) may be positioned with a connecting notch (161) therebetween. A first concave portion (168) may be formed on the opposite surface of the first convex portion (166), and a second concave portion (169) may be formed on the opposite surface of the second convex portion (167).

[0210] The connecting notch (161) may be located in the valley portion (VL2) formed between the first convex portion (166) and the second convex portion (167). The 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 the 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).

[0211] A first tangent angle (K41) formed by a tangent line at an end adjacent to the connecting notch (161) in the first concave portion (168) and an imaginary reference plane (SF1) parallel to the cap plate (21) can be formed smaller than a second tangent angle (K42) formed by a tangent line at an end adjacent to the first side notch (162) in the first concave portion (168) and the reference plane (SF1).

[0212] The first tangent angle (K41) can be 1 to 20 degrees, and the second tangent angle (K42) can be 2 to 30 degrees. In addition, the first tangent angle (K41) can be 2 to 15 degrees, and the second tangent angle (K42) can be 2 to 25 degrees. The difference between the first tangent angle (K41) and the second tangent angle (K42) can be 1 to 10 degrees.

[0213] The third tangent angle (K43) formed by the tangent line at the end adjacent to the connecting notch (161) in the second concave portion (169) and the imaginary reference plane (SF1) parallel to the cap plate (21) can be formed smaller than the fourth tangent angle (K44) formed by the tangent line at the end adjacent to the first side notch (162) in the second concave portion (169) and the reference plane (SF1).

[0214] The third tangential angle (K43) can be from 1 to 20 degrees, and the fourth tangential angle (K44) can be from 2 to 30 degrees. In addition, the third tangential angle (K43) can be from 2 to 15 degrees, and the fourth tangential angle (K44) can be from 2 to 25 degrees. The difference between the third tangential angle (K43) and the fourth tangential angle (K44) can be from 1 to 10 degrees.

[0215] As described above, according to the third embodiment, the side notches (162, 163) and the connecting notch (161) are formed on the inner surface of the vent portion (160) facing the inside of the case, 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.

[0216] In addition, since the tangential angle of the portion connected to the connecting notch (161) in the first concave portion (168) and the second concave portion (169) is formed smaller than the tangential angle of the portion connected to the side notch (162, 163) in the first concave portion (168) and the second concave portion (169), the connecting notch (161) and the side notch (162, 163) can be easily broken.

[0217]

[0218] Below, a secondary battery according to the ninth embodiment of the present invention is described.

[0219] Fig. 23 is a cross-sectional view showing a portion where a connecting notch and a first side notch are located in a vent part according to a ninth embodiment of the present invention, and Fig. 24 is a cross-sectional view showing a portion where a connecting notch and a second side notch are located in a vent part according to a ninth embodiment of the present invention.

[0220] Referring to FIGS. 23 and 24, the secondary battery according to the 9th embodiment has the same structure as the secondary battery according to the 6th embodiment described above except for the vent part (180), so a duplicate description of the same configuration is omitted.

[0221] 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 ninth embodiment have the same structure as the connecting notch and the side notch of the sixth embodiment described above.

[0222] Additionally, the vent portion (180) may further include a first support rib (184) positioned on the outside of the first side notch (182) and surrounding the first side notch (182), and a second support rib (185) positioned 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.

[0223] 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).

[0224] 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 an opposite surface of the first convex portion (186), and a second concave portion (189) may be formed on an opposite surface of the second convex portion (187).

[0225] The connecting notch (181) may be located at the peak (PK1) formed between the first concave portion (188) and the second concave portion (189). The 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 the 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).

[0226]

[0227] Below, a secondary battery according to the tenth embodiment of the present invention is described.

[0228] FIG. 25 is a cross-sectional view showing a portion where a connecting notch and a first side notch are located in a vent part according to the 10th embodiment of the present invention, and FIG. 26 is a cross-sectional view showing a portion where a connecting notch and a second side notch are located in a vent part according to the 10th embodiment of the present invention.

[0229] Referring to FIGS. 25 and 26, the secondary battery according to the 10th embodiment has the same structure as the secondary battery according to the 6th embodiment described above except for the vent part (190), so a duplicate description of the same configuration is omitted.

[0230] 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 an 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 tenth embodiment have the same structure as the connecting notch and the side notch of the sixth embodiment described above.

[0231] Additionally, the vent portion (190) may further include a first support rib (194) positioned on the outside of the first side notch (192) and surrounding the first side notch (192), and a second support rib (195) positioned 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.

[0232] 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).

[0233] 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.

[0234] A first concave portion (198) may be formed on the opposite surface of the first convex portion (196), and a second concave portion (199) may be formed on the opposite surface of the second convex portion (197). The connecting notch may be located at the peak portion (PK2) formed between the first concave portion (198) and the second concave portion (199). The 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 the 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).

[0235]

[0236] Below, a secondary battery according to the 11th embodiment of the present invention is described.

[0237] FIG. 27 is a perspective view illustrating a secondary battery according to the 11th embodiment of the present invention, FIG. 28 is a drawing illustrating a vent protection film according to the 11th embodiment of the present invention, and FIG. 29 is a cross-sectional view taken along the line ⅩⅥ-ⅩⅥ in FIG. 27.

[0238] Referring to FIGS. 27 to 29, the secondary battery (101) according to the 11th embodiment has the same structure as the secondary battery according to the first embodiment described above except for the vent part (130), so a duplicate description of the same configuration is omitted.

[0239] The secondary battery (101) may be formed as a square battery having a case (30) having a roughly square prism shape, and the vent part (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.

[0240] An exhaust hole (36) for gas discharge is formed on the bottom (35) of the case (30), a first step (37) into which a vent part (130) is inserted is formed on the lower outer side of the exhaust hole (36), and a second step (38) into which a vent protection film (60) is inserted can be formed on the lower outer side of the first step (37).

[0241] The vent part (130) is formed in a plate shape and can be fixed to the case (30) by welding. The vent part (130) can include two side notches (132, 133) and a connecting notch (131) connecting the side notches (132, 133). Since the connecting notches (131) and the side notches (132, 133) have the same structure as the connecting notches and the side notches according to the first embodiment described above, a duplicate description thereof will be omitted.

[0242] Meanwhile, a vent protection film (60) may be installed at the bottom of the vent portion (130). The vent protection film (60) may be formed of a flexible film, and a connecting hole (61) for pressure release may be formed in the vent protection film (60). In addition, a fixing area (62) for fixation may be formed on the outside of the vent protection film (61). The fixing area (62) may be adhered or fused to the vent portion (50) or the cap plate (21).

[0243] As described above, according to the sixth embodiment, a vent part (130) is formed on the bottom (35) of the case (30), so that when the vent part (130) is opened, the electrolyte can also be discharged.

[0244] Below, a secondary battery according to the 12th embodiment of the present invention is described.

[0245] Fig. 30 is a perspective view illustrating a secondary battery according to the 12th embodiment of the present invention.

[0246] Referring to FIG. 30, the secondary battery (102) according to the 12th embodiment has the same structure as the secondary battery according to the first embodiment described above except for the vent part (140), so a duplicate description of the same configuration is omitted.

[0247] The secondary battery (102) may be formed as a square battery having a case (30) having a roughly square prism shape, and the vent part (140) may be formed on a side surface (32) of the case (30). The vent part (140) may be formed in a groove shape on any one of the four side surfaces (32) of the case (30). For example, a groove may be directly formed on the outer surface of the case (30) so that the vent part (140) formed as an integral part with the case (30) may be formed on the side surface (32) of the case (30).

[0248] The vent portion (140) may include two side notches (142, 143) and a connecting notch (141) connecting the side notches (142, 143). Since the connecting notches (141) and the side notches (142, 143) have the same structure as the connecting notches and the side notches according to the first embodiment described above, a duplicate description thereof will be omitted.

[0249] As described above, according to the present embodiment, a vent part (140) is formed on the side (32) of the case (30), so that when the vent part (140) is opened, the electrolyte can also be discharged.

[0250]

[0251] Below, a secondary battery according to the eighth embodiment of the present invention is described.

[0252] Fig. 31 is a perspective view illustrating a secondary battery according to the 13th embodiment of the present invention.

[0253] Referring to FIG. 31, the secondary battery (103) according to the 13th embodiment may be formed as a cylindrical battery having a case (80) having a generally cylindrical shape, and the vent portion (120) may be formed on the bottom (85) of the case (80). The bottom (85) of the case (80) may be formed integrally with the case (80) or may be fixed to the case (80) by welding or the like.

[0254] The secondary battery (103) according to the 13th embodiment may be formed of a cylindrical battery of various widely known structures, and is not limited to a specific cylindrical battery structure.

[0255] The vent part (120) is formed on the bottom (85) of the case (80) and can be formed integrally with the case (80) by directly processing a groove on the bottom (85) of the case (80). However, the present invention is not limited thereto, and the vent part (120) may be formed in a plate shape and may be fixed to the bottom (85) of the case (80) by welding.

[0256] The vent portion (120) may include two side notches (122, 123) and a connecting notch (121) connecting the side notches (122, 123). Since the connecting notches (121) and the side notches (122, 123) have the same structure as the connecting notches and the side notches according to the first embodiment described above, a duplicate description thereof will be omitted.

[0257]

[0258] Below, a secondary battery according to the 14th embodiment of the present invention is described.

[0259] Fig. 32 is a plan view from above of a secondary battery according to the 14th embodiment of the present invention. Fig. 33 is a plan view illustrating the vent part of Fig. 32.

[0260] Referring to FIGS. 32 and 33, the secondary battery (104) according to the 14th embodiment has the same structure as the secondary battery according to the first embodiment described above except for the arrangement of the vent part (70), so a duplicate description of the same configuration is omitted.

[0261] The vent portion (70) may extend in the width direction (x-axis direction) of the cap plate (21). The vent portion (70) may have a longitudinal major axis and a width direction, and the major axis may extend in a direction intersecting the longitudinal direction (y-axis direction) of the cap plate (21). In particular, the major axis may be formed perpendicular to the longitudinal direction (y-axis direction) of the cap plate (21), and the minor axis may be formed parallel to the longitudinal direction (y-axis direction) of the cap plate (21).

[0262] The vent part (70) has a major axis (X11) and a minor axis (X12). The major axis (X11) refers to a line segment having the maximum length that passes through the center of the vent part (70) and connects the outer ends of the vent part (70). The major axis (X11) may extend in a direction intersecting the longitudinal direction of the cap plate (21). In addition, the major axis (X11) may extend in a direction perpendicular to the longitudinal direction of the cap plate (21), that is, in the width direction of the cap plate (21). However, the present invention is not limited thereto, and the major axis (X11) may be arranged to be inclined with respect to the longitudinal direction of the cap plate (21).

[0263] The short axis (X12) connects the outer ends of the vent part (70) and is a line segment that extends in the longitudinal direction of the cap plate (21) and has the longest length. The short axis (X12) can connect the outer ends while passing through the center of the vent part (70) and can be perpendicular to the long axis (X11).

[0264] The major axis (X11) is formed longer than the minor axis (X12), and the major axis (X11) can be formed 1.2 to 3.5 times longer than the minor axis (X12).

[0265] The major axis (X11) may extend in the longitudinal direction of the vent portion (70) and the width direction of the cap plate (21), and the minor axis (X12) may extend in the width direction of the vent portion (70) and the length direction of the cap plate (21).

[0266] In this description, the length of the major axis (X11) may mean the length of the vent part (70) exposed to the outside through the vent hole (H2). The major axis (X11) may intersect the longitudinal direction of the cap plate (21). In addition, the major axis (X11) may be formed perpendicular to the longitudinal direction of the cap plate (21).

[0267] When the length of the cap plate (21) is L11, the width of the cap plate (21) is L12, the length of the major axis (X11), which is the longest line segment extending in the width direction of the cap plate from the vent part, is L21, and the length of the minor axis (X12), which is the longest line segment extending in the length direction of the cap plate from the vent part, is L22, the length of the minor axis (X12) (L22) / length of the cap plate (21) (L11) = AL * length of the major axis (X11) (L21) / width (L12) of the cap plate (21) can be satisfied. Here, AL can be a constant that satisfies 0.08≤AL≤0.36.

[0268] When the length (L22) of the short axis (X12) / the length (L11) of the cap plate (21) is made up of the length (L21) of the AL* long axis (X11) / the width (L12) of the cap plate (21), not only can the breaking pressure of the vent part (70) be precisely set, but also when the vent part (70) is opened, non-products such as gas can be quickly discharged. In addition, since sufficient lower space is secured, the gap between the electrode tabs can be increased.

[0269] Meanwhile, the electrode assembly (10) is configured with a structure in which a separator (13) is laminated between a plate-shaped positive electrode (11) and a negative electrode (12). The plate-shaped positive electrode (11) has two positive electrode tabs (15), and the plate-shaped negative electrode (12) has two negative electrode tabs (16).

[0270] The positive electrode tabs (15) may be spaced apart in the longitudinal direction of the cap plate (21), and the negative electrode tabs (16) may also be spaced apart in the longitudinal direction of the cap plate (21). The gap (L31) between the positive electrode tabs (15) may be formed to be larger than the maximum width (L22) of the vent portion (50).

[0271] In more detail, when the spacing between the anode tabs (15) located on one anode (11) formed in a plate shape is L31, the spacing between the anode tabs (15) (L31) = BL * the shortened length (L22) of the vent part (50) can be satisfied. Here, BL can be a constant satisfying 1.2≤BL≤6.5.

[0272] When the gap (L31) between the positive tabs (15) is BL * short-circuit length (L22), the heat generated between the tabs where the current is concentrated is quickly released, and problems such as increased heat generation can be prevented.

[0273] The vent portion (70) 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) are formed as long 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 and arcs.

[0274] Additionally, the connecting notch (51) and the side notches (52, 53) can be broken at a preset pressure. The connecting notch (51) can include a first curved line (51a) and a second curved line (51b) formed in a curved shape. The first curved line (51a) and the second curved line (51b) can be formed in an arc shape and can protrude convexly in different directions.

[0275] The first curve line (51a) may protrude convexly toward one side end of the vent part (70) (in the y-axis direction), and the second curve line (51b) may protrude convexly toward the other side end of the vent part (50) (in the -y-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.

[0276] 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 (x-axis direction) of the connecting notch (51). In addition, 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 the first radius of curvature (R11). Accordingly, the connecting notch (51) can be formed point-symmetrically with respect to the inflection point (CP1).

[0277] Here, the length of the connecting notch (51) can be 0.9 to 1.3 times the length (L21) of the major axis (X11). In addition, the length of the connecting notch (51) can be formed to be longer than the length (L21) of the major axis (X11). For example, the length of the connecting notch (51) can be 1.01 to 1.3 times the length (L21) of the major axis (X11).

[0278] Meanwhile, the two side notches (52, 53) are formed convexly in opposite directions, but can protrude convexly toward the outer side in the longitudinal direction (x-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) can have the same structure and be arranged symmetrically.

[0279] The first side notch (52) may include a curved portion (52a) that is curved in an arc shape, a first straight portion (52b) that is connected to one end of the curved portion (52a) and is connected in a straight line, and a second straight portion (52c) that is connected to the other end of the curved portion (52a) and is connected in a straight line.

[0280] The first straight portion (52b) and the second straight portion (52c) extend in the width direction (x-axis direction) of the cap plate (21) and can be arranged parallel to each other. The curved portion (52a) is formed as an arc having a second radius of curvature (R12) and is formed to partially surround the connecting notch (51).

[0281] In addition, the second side notch (53) may include a curved portion (53a) that is curved in an arc shape, a first straight portion (53b) that is connected to one end of the curved portion (53a) and is connected in a straight line, and a second straight portion (53c) that is connected to the other end of the curved portion (53a) and is connected in a straight line. In addition, the connecting notch (51) may be connected to the longitudinal central portions of the first side notch (52) and the second side notch (53).

[0282] The first side notch (52) and the second side notch (53) are spaced apart from each other and may be formed to partially surround the connecting notch (51). Here, the first side notch (52) and the second side notch (53) may surround the connecting notch (51) by 50% to 90%.

[0283] The length of the connecting notch (51) may be the (shortest / straight-line) distance (projection length) between the two points that are the farthest from each other on the connecting notch (51) and / or the length of the (curved) path (path length) along which the connecting notch (51) extends. The connecting notch (51) may be considered to be “surrounded” by two side notches (52, 53) if the side notches (52, 53) are positioned on either side of the connecting notch (51) (e.g., in a direction perpendicular to the connecting notch (51) and / or in a direction perpendicular to a line connecting the two points that are the farthest from each other on the connecting notch (51).

[0284] Meanwhile, the first side notch (52) and the second side notch (53) have the same length, and the lengths of the side notches (52, 53) can be formed to be longer than the length of the connecting notch (51). The lengths of the side notches (52, 53) can be 1.02 to 1.27 times the length of the connecting notch (51). For example, the length of the connecting notch (51) can be 18 to 55 mm, and the lengths of the side notches (52, 53) can be 19 to 60 mm.

[0285] If the length of the side notches (52, 53) is 1.02 to 1.27 times the length of the connecting notch (51), not only the connecting notch (51) may break first, but also the side notches (52, 53) may break first. If the side notches (52, 53) break first, two openings may be formed, and if the connecting notch (51) breaks first, two pieces may rise to form one opening.

[0286] In addition, when the length of the connecting notch (51) is L41 and the length of the side notch (52, 53) is L42, 'connecting notch (L41)' + 2 * 'length of side notch (L42)' = DL * 'maximum width of the vent part (L21)' can be satisfied. Here, DL can be a constant of 2.5≤DL≤6.5.

[0287] Meanwhile, the first gap (G11), which is the maximum gap between the major axis (X11) and the connecting notch (51), may be 0.05 to 0.4 times the second gap (G12), which is the maximum gap between the major axis (X11) and the first side notch (52).

[0288]

[0289] Below, a secondary battery according to the 15th embodiment of the present invention is described.

[0290] Figure 34 is a plan view of a secondary battery according to the 15th embodiment of the present invention.

[0291] Referring to FIG. 34, the secondary battery (106) according to the 15th embodiment has the same structure as the secondary battery according to the first embodiment described above except for the arrangement of the vent part (90), so a duplicate description of the same configuration is omitted.

[0292] The secondary battery (106) may be formed as a square battery having a case (30) having a roughly square prism shape, and the vent part (90) may be fixed to the cap plate (21). 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.

[0293] The vent part (90) is formed in a plate shape and can be fixed to the cap plate (21) by welding. The vent part (90) can be arranged so that its length direction is inclined with respect to the length direction of the cap plate (21). The vent part (90) has a major axis (X11) and a minor axis (X12). The major axis (X11) refers to a line that passes through the center of the vent part (240) and connects the outer ends, but is the longest line. The minor axis (X12) refers to a line that passes through the center of the vent part (90) and connects the outer ends, but is perpendicular to the major axis (X11).

[0294] The major axis (X11) of the vent portion (90) can be arranged to be inclined with respect to the longitudinal direction of the cap plate (21). The inclination angle (K12) formed by the major axis (X11) of the vent portion (90) and the longitudinal direction of the cap plate (21) can be 60 to 120 degrees.

[0295] As in the present embodiment, when the major axis (X11) of the vent part (90) is arranged at an angle of 60 to 120 degrees with respect to the longitudinal direction of the cap plate (21), the proportion of the vent part (240) with respect to the longitudinal direction of the cap plate (21) is reduced, and more free space can be secured at the bottom of the cap plate (21). In addition, the direction of gas discharge through the vent part (90) can be easily controlled by adjusting the angle of inclination of the vent part (240).

[0296]

[0297] Above, one embodiment of the present invention has been described, but a person having ordinary skill in the art will be able to modify and change the present invention in various ways by adding, changing, deleting or adding components, etc., within the scope that does not depart from the spirit of the present invention described in the claims, and this will also be considered to be included within the scope of the rights of the present invention.

Claims

1. Case; An electrode assembly inserted into the above case; a cap plate coupled to the above case; and including a vent formed in the case or the cap plate; A secondary battery, wherein the vent portion includes a plurality of side notches and a connecting notch connecting the side notches, and the connecting notch includes at least one curved line.

2. In paragraph 1, A secondary battery, wherein the above curve line continues in an arc shape having a first radius of curvature, and at least one of the side notches is curved in an arc shape and includes a curved portion having a second radius of curvature.

3. In paragraph 2, A secondary battery, wherein the above connecting notch is located on the concave inner side of the facing curved portion of the side notch.

4. In paragraph 2, The above first radius of curvature is larger than the above second radius of curvature, A secondary battery, wherein the first radius of curvature is 1.1 to 5.5 times the second radius of curvature.

5. In paragraph 2, A secondary battery, wherein the side notch includes a first straight portion connected to one end of the curved portion and extending in a straight line, and a second straight portion connected to the other end of the curved portion and extending in a straight line.

6. In paragraph 1, A secondary battery, wherein the above 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.

7. In paragraph 6, A secondary battery, wherein the first curve line and the second curve line have the same radius of curvature.

8. In paragraph 6, In the above connecting notch, an inflection point is formed where the first curve line and the second curve line meet, A secondary battery, wherein the tangent line at the above inflection point is located at the center of the width direction of the vent part and the acute angle of inclination at which it meets the imaginary reference line extending in the length direction of the vent part is 5 to 60 degrees.

9. In paragraph 1, A secondary battery, wherein the first interval, which is the maximum interval from the connecting notch on a virtual reference line extending in the longitudinal direction of the vent portion, is 0.05 to 0.4 times the second interval, which is the maximum interval from the virtual reference line to the side notch.

10. In paragraph 1, A secondary battery, wherein the vent portion includes two side notches, and the two side notches are formed to surround the connecting notch by 50% to 90%.

11. In paragraph 1, A secondary battery, wherein the vent portion includes a base having a first side and a second side opposite to the first side, and the connecting notch and the side notch are formed on the first side or the second side.

12. In paragraph 11, The above-mentioned vent portion includes a first linear protrusion convexly protruding from the first side of the base and a first linear groove concavely recessed from the second side of the base, The first linear protrusion and the first linear groove each extend along the connecting notch, A secondary battery, wherein the above connecting notch is formed in the first linear protrusion or the first linear groove.

13. In paragraph 12, The above-mentioned vent portion includes a second linear protrusion convexly protruding from the first side of the base and a second linear groove concavely recessed from the second side of the base, The second linear protrusion and the second linear groove each extend along the side notch, A secondary battery, wherein the side notch is formed in the second linear protrusion or the second linear groove.

14. In paragraph 1, The above vent portion includes a first groove portion surrounding the side notches and the connecting notch, and a second groove portion located at the bottom of the first groove portion and extending in the longitudinal direction of the connecting notch, A secondary battery, wherein the side notches are located in the first groove portion, and the connecting notch is located in the second groove portion.

15. In paragraph 1, A secondary battery, wherein the vent portion is located on at least one of the cap plate, the bottom of the case, and the side of the case.

16. In paragraph 1, The above curve line is a secondary battery composed of curves having multiple radii of curvature.

17. In paragraph 11, The above-mentioned vent portion includes a first convex portion and a second convex portion that are arranged adjacent to each other and have the connecting notch positioned therebetween, A secondary battery, wherein the first convex portion and the second convex portion extend between the connecting notch and one of the plurality of side notches and protrude from the base.

18. In paragraph 17, Both the first convex portion and the second convex portion protrude from the base toward the first side or the second side, A secondary battery, wherein each of the first convex portion and the second convex portion protrudes from the base toward the first side and the second side, respectively.

19. In paragraph 1, A secondary battery in which the longitudinal direction of the above-mentioned vent portion is parallel to the longitudinal direction of the above-mentioned cap plate.

20. In paragraph 1, A secondary battery in which the longitudinal direction of the above-mentioned vent section continues in a direction intersecting the longitudinal direction of the above-mentioned cap.

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