Secondary battery and method of manufacturing the same

Abstract

The present disclosure relates to a secondary battery and a method of manufacturing the same. The secondary battery includes: an electrode assembly; a cylindrical case including a bottom portion, a side wall portion connected to the bottom portion, and an upper opening portion facing the bottom portion, the cylindrical case accommodating the electrode assembly; a cap assembly coupled to the upper opening portion; and a gasket between the cylindrical housing and the cover assembly, the gasket including: a cylindrical body portion; a first extension portion extending from the cylindrical body portion toward the inside of the cylindrical housing; and a second extension portion extending obliquely downward from the first extension portion toward the bottom portion of the cylindrical housing, the second extension portion including a lower surface, an inner surface, and an inclined portion between the lower surface and the inner surface and extending obliquely with respect to the lower surface and the inner surface.

Description

Technical Field

[0001] This disclosure relates to a secondary battery and a method for manufacturing the secondary battery. Background Technology

[0002] Unlike primary batteries, which are not designed for (re)charging, secondary (or rechargeable) batteries are designed to be discharged and recharged. Low-capacity secondary batteries are used in portable small electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while high-capacity secondary batteries are widely used as power sources for driving motors in hybrid and electric vehicles and for storing electricity (e.g., household and / or utility-scale power storage). A secondary battery typically comprises an electrode assembly consisting of positive and negative electrodes, a housing that houses the electrode assembly, and electrode terminals connected to the electrode assembly.

[0003] A secondary battery can be manufactured by inserting an electrode assembly into a housing and then sealing the housing with a cover assembly. In the case of a cylindrical secondary battery, a rolled portion and a crimped portion can be formed in the upper part of the housing to secure the cover assembly.

[0004] The information disclosed in this background section is intended to enhance the understanding of the background art of this disclosure, and therefore may contain information that does not constitute related (or prior art). Summary of the Invention

[0005] According to some embodiments of this disclosure, a secondary battery is provided, the secondary battery comprising: an electrode assembly; a cylindrical housing including a bottom portion, a sidewall portion connected to the bottom portion, and an upper opening portion facing the bottom portion, and accommodating the electrode assembly; a cover assembly coupled to one end of the sidewall portion of the housing; and a gasket between the housing and the cover assembly, wherein the gasket comprises: a cylindrical body portion; a first extension portion extending from the body portion toward the interior of the housing; and a second extension portion extending obliquely downward from the first extension portion toward the bottom portion, the second extension portion including a lower surface, an inner surface, and an oblique portion formed by chamfering the lower surface and the inner surface.

[0006] According to some embodiments of this disclosure, the width w1 of the inclined portion can be 30% to 70% of the width w2 of the lower surface before it is beveled.

[0007] According to some embodiments of this disclosure, the height h1 of the inclined portion can be 30% to 70% of the height h2 of the inner surface of the second extension portion before it is obliquely cut.

[0008] According to some embodiments of this disclosure, the vertical cross-section of the inclined portion can be in the form of a straight line.

[0009] According to some embodiments of this disclosure, the vertical cross-section of the inclined portion can be in the form of a curve.

[0010] According to some embodiments of this disclosure, the sidewall portion of the housing includes a crimped portion formed by bending an end portion of the sidewall portion and a rolled portion formed by bending the sidewall portion inward in a downward direction in the crimped portion, and the electrode assembly can be accommodated below the rolled portion.

[0011] According to some embodiments of this disclosure, the main body portion of the pad may be configured to be in close contact with the crimping portion, and at least a portion of the first extension portion and the second extension portion of the pad may be configured to be in close contact with the roll-up portion and surround at least a portion of the inner surface of the roll-up portion.

[0012] According to some embodiments of this disclosure, an insulating plate may be further provided on the upper surface of the electrode assembly, and the second extension may be provided at a predetermined distance from the insulating plate, while at least a portion of the second extension is in close contact with the rolled portion.

[0013] According to some embodiments of this disclosure, the distance between the second extension portion and the insulating plate can be 0.3 mm or more.

[0014] According to some embodiments of this disclosure, the cover assembly may include an upper cover, a safety vent disposed below the upper cover, and a lower cover disposed below the safety vent and electrically connected to the electrode assembly.

[0015] According to some embodiments of this disclosure, the gasket can insulate the housing from the safety vent and the top cover.

[0016] According to some embodiments of this disclosure, a method for manufacturing a secondary battery is provided, the method comprising: preparing a cylindrical housing including a bottom portion, a sidewall portion connected to the bottom portion, and an upper opening portion facing the bottom portion; inserting an electrode assembly into the housing; forming a rolled portion by bending the sidewall portion; providing a gasket and cap assembly to seal the upper opening portion; and forming a crimped portion by bending an end portion of the sidewall portion, wherein the gasket includes a cylindrical body portion, a first extension portion extending from the body portion toward the interior of the housing, and a second extension portion extending obliquely downward from the first extension portion toward the bottom portion, and the second extension portion includes a lower surface, an inner surface, and an oblique portion formed by beveling the lower surface and the inner surface.

[0017] According to some embodiments of this disclosure, the width of the inclined portion can be 30% to 70% of the width of the lower surface before it is beveled.

[0018] According to some embodiments of this disclosure, the height of the inclined portion can be 30% to 70% of the height of the inner surface before it is beveled.

[0019] According to some embodiments of this disclosure, the vertical cross-section of the inclined portion can be in the form of a straight line.

[0020] According to some embodiments of this disclosure, the vertical cross-section of the inclined portion can be in the form of a curve.

[0021] According to some embodiments of this disclosure, forming the crimped portion may include the following steps: bending the end portion of the sidewall portion such that at least a portion of the first extension portion and the second extension portion of the pad are in close contact with the crimped portion while the second extension portion moves obliquely downward toward the bottom portion.

[0022] According to some embodiments of this disclosure, an insulating plate may be disposed to contact the upper surface of the electrode assembly, and the second extension may be disposed at a predetermined distance from the insulating plate, while at least a portion of the second extension is in close contact with the rolled portion.

[0023] According to some embodiments of this disclosure, the distance between the second extension portion and the insulating plate can be 0.3 mm or more.

[0024] According to some embodiments of this disclosure, the cover assembly may include an upper cover, a safety vent disposed below the upper cover, and a lower cover disposed below the safety vent and electrically connected to the electrode assembly, wherein the gasket can insulate the housing from the safety vent and the upper cover. Attached Figure Description

[0025] The following accompanying drawings illustrate embodiments of the present disclosure and, together with the detailed description of the present disclosure, further describe aspects and features of the present disclosure. Therefore, the present disclosure should not be construed as limited to the drawings.

[0026] Figure 1 This is a diagram illustrating an example of a secondary battery according to an embodiment of the present disclosure.

[0027] Figure 2 This is a diagram used to explain the compression process of the gasket according to embodiments of the present disclosure.

[0028] Figure 3 This is a diagram showing a comparative example of the padding.

[0029] Figure 4 This is a cross-sectional side view showing an example of a liner according to an embodiment of the present disclosure.

[0030] Figure 5 This is a partial enlarged view illustrating the shape of a pad according to an embodiment of the present disclosure.

[0031] Figure 6 This is a partially enlarged view illustrating the shape of a pad according to another embodiment of the present disclosure.

[0032] Figure 7 This is a diagram illustrating an example of the application of a pad according to another embodiment of this disclosure.

[0033] Figure 8 This is a flowchart of a method for manufacturing a secondary battery according to another embodiment of the present disclosure. Detailed Implementation

[0034] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The terms or words used in this specification and claims should not be construed as limited to their general or dictionary meanings, and should be interpreted in a manner consistent with the technical spirit of the present disclosure, based on the principle that the inventor is capable of interpreting the concepts of the terms appropriately as his / her own lexicographer.

[0035] The embodiments described in this specification and the configurations shown in the accompanying drawings are only some of the embodiments of this disclosure and do not represent all the technical ideas, aspects, and features of this disclosure. Accordingly, it should be understood that various equivalents and modifications that can replace or modify the embodiments described herein may exist at the time of filing this application.

[0036] It will be understood that when an element or layer is referred to as being "on" another element or layer, "connected to," or "linked to" another element or layer, it can be directly on, directly connected to, or linked to the other element or layer, or one or more intermediary elements or layers may be present. When an element or layer is referred to as being "directly on" another element or layer, "directly connected to," or "directly linked to" another element or layer, no intermediary element or layer is present. For example, when a first element is described as being "linked" or "connected" to a second element, the first element can be directly linked to or connected to the second element, or the first element can be indirectly linked to or connected to the second element via one or more intermediary elements.

[0037] In the figures, the dimensions of various elements, layers, etc., may be exaggerated for clarity of illustration. The same reference numerals denote the same elements. As used herein, the term “and / or” includes any and all combinations of one or more of the related listed items. Furthermore, when describing embodiments of this disclosure, the use of “may” refers to “one or more embodiments of this disclosure.” Expressions such as “at least one of…” and “any one of…” modify the entire list of elements when following it, and not individual elements within that list. When phrases such as “at least one of A, B, and C,” “at least one of A, B, or C,” “at least one selected from the group of A, B, and C,” or “at least one selected from A, B, and C” are used to refer to a list of elements A, B, and C, the phrase may refer to any one of A, B, and C and all suitable combinations or subsets of them, such as A, B, C, A and B, A and C, B and C, or A and B and C. As used herein, the term “use” may be considered synonymous with the term “utilize.” As used herein, the terms “substantially,” “approximately,” and similar terms are used as approximate terms rather than as terms of degree, and are intended to describe the inherent variation of a measured or calculated value that would be recognized by one of ordinary skill in the art.

[0038] It will be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or segment from another element, component, region, layer, or segment. Therefore, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment.

[0039] For ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” and “above” are used herein to describe the relationship between one element or feature illustrated in the figure and another element or feature. It will be understood that spatial relative terms are intended to cover different orientations of the device in use or operation other than the orientation depicted in the figure. For example, if the device in the figure is flipped, an element described as “below” or “under” other elements or features would then be oriented as “above” or “above” other elements or features. Therefore, the term “below” can encompass both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptive terms used herein should be interpreted accordingly.

[0040] The terminology used herein is for the purpose of describing embodiments of this disclosure and is not intended to limit this disclosure. As used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprising” and / or “including” as used in this specification specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0041] Furthermore, any numerical range disclosed and / or described herein is intended to include all subranges with the same numerical precision contained within the described range. For example, the range “1.0 to 10.0” is intended to include all subranges between the described minimum value of 1.0 and the described maximum value of 10.0 (and inclusive of both), i.e., a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as 2.4 to 7.6. Any maximum numerical limit described herein is intended to include all lower numerical limits contained therein, and any minimum numerical limit described herein is intended to include all higher numerical limits contained therein. Accordingly, the applicant reserves the right to amend this specification, including the claims, to explicitly describe any subranges contained within the scope explicitly described herein.

[0042] Referring to two compared elements, features, etc., as “identical” can mean that they are “substantially identical.” Therefore, the phrase “substantially identical” can include cases where the deviation is considered low in the art (e.g., 5% or less). Additionally, when a parameter is said to be consistent in a given region, it can mean that it is consistent in terms of average value.

[0043] Throughout this specification, unless otherwise stated, each element may be singular or plural.

[0044] Arranging any element "above (or below)" or "above (below)" another element can mean that the arbitrary element can be configured to contact the upper (or lower) surface of the element, and the other element can also be located between the element and the arbitrary element disposed on (or below) the element.

[0045] Additionally, it will be understood that when a component is referred to as a “link,” “connect,” or “attached” to another component, these components can be directly “connected,” “linked,” or “attached” to each other, or another component can be “between” these components.

[0046] Throughout this specification, unless otherwise stated, the phrase "A and / or B" means A, B, or A and B. That is, "and / or" includes any one or all of the listed items. Unless otherwise stated, the phrase "C to D" means C and below D.

[0047] In this disclosure, for clarity, the dimensions and relative dimensions of the areas shown in the accompanying drawings may be exaggerated. That is, the dimensions shown in the drawings are for ease of understanding only and are not limiting. Furthermore, throughout the specification, the same reference numerals denote the same parts.

[0048] Figure 1 This is a perspective view illustrating an example of a secondary battery 100 according to an embodiment of the present disclosure. Figure 1 As shown, the secondary battery 100 may include: an electrode assembly 110; a housing 120 that houses the electrode assembly 110 and an electrolyte therein; a cover assembly 130 that is connected to an opening (e.g., an upper opening portion) of the housing 120 to seal the housing 120; and an insulating plate 150 disposed inside the housing 120 between the electrode assembly 110 and the cover assembly.

[0049] The electrode assembly 110 may include a diaphragm 114, a first electrode 112, and a second electrode 113, and may be wound around a winding axis Y to form an electrode core shape, with the first electrode 112 and the second electrode 113 positioned between the diaphragm 114.

[0050] The first electrode 112 may include a first substrate and a first active material layer disposed on the first substrate. A first lead tab 115 may extend outward from a first uncoated portion of the first substrate, wherein the first active material layer is not located in the first uncoated portion, and the first lead tab 115 may be electrically connected to the cover assembly 130.

[0051] The second electrode 113 may include a second substrate and a second active material layer disposed on the second substrate. A second lead tab 116 may extend outward from a second uncoated portion of the second substrate, wherein the second active material layer is not located in the second uncoated portion, and the second lead tab 116 may be electrically connected to the housing 120. The first lead tab 115 and the second lead tab 116 may extend in opposite directions.

[0052] The first electrode 112 can be used as a positive electrode. In this case, the first substrate can be made of, for example, aluminum foil, and the first active material layer can include, for example, a transition metal oxide. The second electrode 113 can be used as a negative electrode. In this case, the second substrate can be made of, for example, copper foil or nickel foil, and the second active material layer can include, for example, graphite.

[0053] The separator 114 can be used to prevent short circuits between the first electrode 112 and the second electrode 113 while allowing lithium ions to move. The separator 114 can be made of, for example, a polyethylene membrane, a polypropylene membrane, or a polyethylene-polypropylene membrane.

[0054] The housing 120 can accommodate the electrode assembly 110 and the electrolyte, and the housing 120 and the cover assembly 130 can form the shape of the secondary battery 100. The housing 120 may include a substantially cylindrical sidewall portion 124 and a bottom portion 122 connected to one side of the sidewall portion 124. An inwardly deformed rolled portion 126 may be provided on the sidewall portion 124, and an inwardly bent crimped portion 128 may be provided on the open end portion of the sidewall portion 124.

[0055] The crimping portion 126 prevents the electrode assembly 110 from moving inside the housing 120 and facilitates the securing of the gasket 140 and the cover assembly 130. The crimping portion 128 secures the cover assembly 130 by pressing the edge of the cover assembly 130 via the gasket. The housing 120 may be made of, for example, nickel-plated steel.

[0056] The cover assembly 130 may include a safety vent 134, an upper cover 132 disposed above the safety vent 134, and a lower cover 138 disposed below the safety vent 134. The cover assembly 130 may further include an insulating member 136 and a gasket 140. The insulating member 136 is inserted between the safety vent 134 and the lower cover 138 to prevent a portion of the safety vent 134, except for its central portion, from contacting the lower cover 138. The gasket 140 provides insulation between the cover assembly 130 and the housing 120. In the safety vent 134, the central portion may contact the lower cover 138, and the portion supported by the insulating member 136 may be spaced apart from the lower cover 138. The safety vent 134 may have a notch that ruptures and releases gas when the internal pressure rises above a certain level.

[0057] An insulating plate 150 may be provided to contact the electrode assembly 110 below the coiled portion 126, and a tab opening for leading out the first lead tab 115 may be provided in the insulating plate 150. A cover assembly 130 electrically connected to the first electrode 112 via the first lead tab 115 may face the electrode assembly 110 with the insulating plate 150 between them, and the insulating plate 150 may be used to maintain insulation from the electrode assembly 110.

[0058] Figure 2This diagram illustrates the compression process of the gasket 240 according to embodiments of the present disclosure. In one embodiment, the housing 220 may include a bottom portion, a sidewall portion connected to the bottom portion, and an opening facing the bottom portion. A cover assembly 230 may be coupled to one end of the sidewall portion of the housing 220. The portion of the sidewall portion of the housing 220 that is bent and connected to the cover assembly 230 may be referred to as a crimped portion. For ease of explanation, the orientation of the bottom portion of the housing 220 is defined as a downward direction, and the orientation of the cover assembly 230 coupled to one end of the sidewall portion of the housing 220 is defined as an upward direction.

[0059] In one embodiment, the gasket 240 may be located between the housing 220 and the cover assembly 230 to insulate the housing 220 and the cover assembly 230. Specifically, the cover assembly 230 may include a safety vent 234, an upper cover 232 disposed above the safety vent 234, a lower cover 238 disposed below the safety vent 234, and an insulating member 236 disposed between the safety vent 234 and the lower cover 238. The housing 220 may include a crimp portion 228 formed by bending the end portions of the sidewall portions and a rolled portion 226 formed by bending the sidewall portions inward below the crimp portion 228. The cover assembly 230 and the gasket 240 may be mounted above the rolled portion 226. As the crimp portion 228 bends, the gasket 240 is compressed, and the cover assembly 230 and the gasket 240 may engage / secure to the housing 220.

[0060] In one embodiment, at least a portion of the gasket 240 may surround the crimped portion 226, thereby insulating the housing 220 from the cover assembly 230 and / or the lead tab. Specifically, the gasket 240 may include a body portion 242, a first extension portion 244 extending from the body portion 242 toward the inside (e.g., interior) of the housing 220, and a second extension portion 246 extending obliquely downward from the first extension portion 246. For example, the second extension portion 246 may extend downward from the first extension portion 244 toward the bottom portion of the housing 220 at a predetermined angle. When the crimped portion 228 is bent, the body portion 242 of the gasket 240 may come into close contact with the crimped portion 228, and the first extension portion 244 may come into close contact between the cover assembly 230 and the crimped portion 226. The second extension portion 246 may be configured to surround at least a portion of the inner surface of the crimped portion 226.

[0061] refer to Figure 2The distribution direction of the pressure applied to the gasket 240 by the bending of the crimp portion 228 can be examined. When the end portion of the side wall portion of the housing 220 is bent to form the crimp portion 228, the gasket 240 can be compressed in the vertical direction by being squeezed between the crimp portion 226 and the crimp portion 228. In this case, region A is the region where the pressure applied from above the gasket 240 generates a load on the gasket 240, and region B is the region where the pressure applied from above the gasket 240 generates stress on the gasket 240.

[0062] In this situation, as the gasket 240 is compressed in the vertical direction, sagging towards the bottom portion of the housing 220 may occur. Specifically, the pressure transmitted to the gasket 240 not only compresses the main body portion 242 of the gasket 240, but can also be transmitted along the direction of the arrows shown to the second extension portion 246 of the gasket 240 and the cover assembly 230. Due to the force transmitted in this way, the second extension portion 246 may sag towards the bottom portion of the housing 220 and move obliquely downwards. In this case, the end portion of the second extension portion 246 may interfere with the electrode assembly housed in the housing 220, resulting in a battery short circuit. For example, this phenomenon may occur due to a reduction in free space inside the housing 220 caused by a design that increases battery capacity.

[0063] Figure 3 This is a diagram illustrating a comparative example 300 of the gasket 340. For example, the gasket 340 may include a main body portion 342, a first extension portion 344 extending from the main body portion 342, and a second extension portion 346 extending obliquely downward from the first extension portion 346. For example, the second extension portion 346 may extend downward from the first extension portion 344 toward the bottom portion of the housing at a predetermined angle. The second extension portion 346 may be configured to surround at least a portion of the coiled portion 326 formed in the housing. The electrode assembly may be disposed below the coiled portion 326, so that the electrode assembly and the insulating plate disposed on the upper surface of the electrode assembly may be spaced apart from the lower line L1 of the coiled portion 328 by a certain distance.

[0064] For example, refer to Figure 3 During the crimping process, the end portion of the second extension 346 can extend downward at an angle, such that the end line L2 of the second extension 346 can be formed below the lower line L1 of the coiled portion 326. In this case, the risk of fire due to a battery short circuit may increase because the electrode assembly and insulating plate located below the lower line L1 of the coiled portion 326 are compressed by the second extension 346.

[0065] Figure 4This is a cross-sectional side view illustrating an example of a pad 400 according to an embodiment of the present disclosure. As illustrated, the pad 400 may include a generally cylindrical body portion 410 extending along a vertical direction (Y-axis) to have a predetermined length, a first extension portion 420 extending horizontally (X-axis) to be substantially perpendicular to the body portion 410, and a second extension portion 430 extending obliquely downward from the first extension portion 420 at a predetermined angle.

[0066] In one embodiment, the first extension 420 may extend inwardly from the main body 410 into the housing. Here, the expression "substantially perpendicular" means that the angle between the main body 410 and the first extension 420 is a right angle or close to a right angle.

[0067] In one embodiment, the second extension 430 may include an inner surface 432 formed along a direction parallel to the extension direction of the main body 410 (Y-axis), a lower surface 434 formed along a direction perpendicular to the inner surface 432 (X-axis), and an inclined portion 436 obtained by beveling the inner surface 432 and the lower surface 434. The inclined portion 436 is formed by beveling at least a portion of the lower surface 434 and at least a portion of the inner surface 432 at the corners where the lower surface 434 and the inner surface 432 of the second extension 430 contact each other. The inclined portion 436 may be formed such that the end portion of the second extension 430 is inclined upward at a predetermined angle (e.g., toward the inner surface 432). For example, refer to Figure 4 The inclined portion 436 may extend between and connect the lower surface 434 and the inner surface 432, and may extend obliquely relative to each of the lower surface 434 and the inner surface 432. For example, refer to Figure 4 An obtuse angle may be defined within the second extension 430 between the inclined portion 436 and each of the lower surface 434 and the inner surface 432. (See later...) Figure 5 and Figure 6 A specific example of the shape of the pad 400 is described in detail.

[0068] With this configuration, interference between the electrode assembly and the second extension 430 can be prevented even when the second extension 430 droops towards the bottom and its end portion moves downward at an angle. Specifically, the corners where the lower surface 434 and the inner surface 432 of the second extension 430 contact each other can be beveled, allowing the flat surface of the inclined portion 436 to face the electrode assembly side, thereby minimizing interference between the second extension 430 and the electrode assembly.

[0069] exist Figure 4For ease of explanation, only the formation of the inclined portion 436 by beveling the corner where the lower surface 434 and the inner surface 432 of the second extension portion 430 meet is explained to illustrate the shape of the second extension portion 430. For example, the inner surface 432, the lower surface 434, and the inclined portion 436 of the second extension portion 430 can be formed into the desired shape in one step during the initial manufacturing stage by injection molding or the like (for example, the inclined portion 436 can be directly injection molded into a flat shape without a separate beveling stage).

[0070] Figure 5 This is a partial enlarged view illustrating the shape of a pad 500 according to an embodiment of the present disclosure. Figure 5 It can be Figure 4 A magnified view of a portion of region C of the padding shown.

[0071] In one embodiment, the pad 500 may include a generally cylindrical body portion 410, a first extension portion 420 extending from the body portion 410 in a generally vertical (e.g., orthogonal) direction, and a second extension portion 430 extending obliquely downward from the first extension portion 420 at a predetermined angle.

[0072] The main body portion 410 can extend along a vertical direction (Y-axis) to have a predetermined length and includes an inner surface 412 and an outer surface 414. The outer surface 414 of the main body portion 410 can be in close contact (e.g., direct contact) with the crimped portion of the housing. For example, when forming the crimped portion, the upper portion of the main body portion 410 can be bent substantially horizontally (X-axis) together with the end portion of the sidewall portion of the housing. In this case, the inner surface 412 of the main body portion 410 can contact the cover assembly, and the outer surface 414 of the main body portion 410 can contact the crimped portion of the housing. For example, the thickness of the main body portion 410 (i.e., the distance between the inner surface 412 and the outer surface 414 of the main body portion 410) can be approximately 0.6 mm to 0.7 mm.

[0073] The first extension portion 420 may extend horizontally (X-axis) substantially perpendicular to the main body portion 410 and may include an upper surface 422 and a lower surface 424. The upper surface 422 of the first extension portion 420 may extend from the inner surface 412 of the main body portion 410 and contact the lower portion of the cover assembly. The lower surface 424 of the first extension portion 420 may extend from the outer surface 414 of the main body portion 410 and contact the upper portion of the rolled portion. The outer surface 414 of the main body portion 410 and the lower surface 424 of the first extension portion 420 may be connected in an arcuate shape with a predetermined curvature. For example, the diameter of the arcuate portion at the junction of the outer surface 414 of the main body portion 410 and the lower surface 424 of the first extension portion 420 may be approximately 0.4 mm. For example, the inner surface 412 of the main body 410 and the upper surface 422 of the first extension 420 can be connected perpendicularly to each other, or they can be connected in an arc shape with a predetermined curvature, similar to the connection between the outer surface 414 of the main body 410 and the lower surface 424 of the first extension 410. For example, the thickness of the first extension 420 (which is the distance between the upper surface 422 and the lower surface 424 of the first extension 420) can be approximately 0.75 mm.

[0074] The second extension 430 may extend downward at a predetermined angle from the first extension 420, and may include an inner surface 432, a lower surface 434, an inclined portion 436, an upper inclined surface 437, and a lower inclined surface 438.

[0075] In one embodiment, the upper inclined surface 437 of the second extension portion 430 can extend downward at a predetermined angle from the upper surface 422 of the first extension portion 420. For example, the upper inclined surface 437 of the second extension portion 430 can extend downward at a predetermined angle to the height where the lower surface 424 of the first extension portion 420 is formed, and then extend a predetermined length in the horizontal direction (X-axis). The downward inclined portion and the horizontal extension portion of the upper inclined surface 437 can be connected in an arc shape. For example, the diameter of the arc portion formed by connecting the downward inclined portion and the horizontal extension portion of the upper inclined surface 437 can be approximately 0.5 mm. In addition, the angle of inclination of the upper inclined surface 437 of the second extension portion 430 relative to the upper surface 422 of the first extension portion 420 can be approximately 40 degrees.

[0076] In one embodiment, the downwardly inclined surface 438 of the second extension 430 may extend downwardly at a predetermined angle from the lower surface 424 of the first extension 420. For example, the angle at which the downwardly inclined surface 438 of the second extension 430 is inclined relative to the lower surface 424 of the first extension 420 may approximately correspond to the angle at which the upwardly inclined surface 437 of the second extension 430 is inclined relative to the upper surface 422 of the first extension 420. For example, the downwardly inclined surface 438 may have an overall arcuate shape. For example, the diameter of the arcuate portion of the downwardly inclined surface 438 may be approximately 0.6 mm. The downwardly inclined surface 438 of the second extension 430 may be configured to surround at least a portion of the inner surface of the coiled portion.

[0077] In one embodiment, a lower surface 434 and an inner surface 432 may be formed at the end portion of the second extension 430. The lower surface 434 of the second extension 430 may extend horizontally (X-axis) from the lower inclined surface 438, and the inner surface 432 of the second extension 430 may extend vertically (Y-axis) from the upper inclined surface 437.

[0078] In one embodiment, the inclined portion 436 may be formed, for example, at an obtuse angle relative to each of the lower surface 434 and the inner surface 432 within the second extension 430. The inclined portion 436 may be formed by obliquely cutting at least a portion of the lower surface 434 and at least a portion of the inner surface 432 at the corner where the lower surface 434 and the inner surface 432 of the second extension 430 contact each other. For example, the inclined portion 436 may be an imaginary oblique cut of an imaginary corner (e.g., formed by an imaginary oblique cut of an imaginary corner formed by an imaginary intersection between the extensions of the lower surface 434 and the inner surface 432 of the second extension 430).

[0079] In one embodiment, the inclined portion 436 can be formed by beveling at least a portion of the lower surface 434. Accordingly, the width w1 of the inclined portion 436 can be formed to be 30% to 70% of the width w2 of the lower surface 434 before beveling. Alternatively, the inclined portion 436 can be formed by beveling at least a portion of the inner surface 432. Accordingly, the height h1 of the inclined portion 436 can be 30% to 70% of the height h2 of the inner surface 432 before beveling. For example, refer to... Figure 5 The first width w1 of the extension line from the lower surface 434 to the imaginary corner can be 30% to 70% of the second width w2 (i.e., the total width of the lower surface 434 and the first width w1). For example, refer to Figure 5 The first height h1 of the extension line from the inner surface 432 to the imaginary corner can be 30% to 70% of the second height h2 (i.e., the total height of the inner surface 432 and the first height h1).

[0080] For example, the width w2 of the lower surface 434 of the second extension 430 before being beveled can be approximately 0.85 mm, and the width of the lower surface 434 after being beveled can be approximately 0.25 mm. Accordingly, the width w1 of the inclined portion 436 formed by beveling a portion of the lower surface 434 can be approximately 0.6 mm. For example, the inclined portion 436 can be formed by beveling approximately 70% of the width w2 of the lower surface 434.

[0081] As another example, the height h2 of the inner surface 432 of the second extension 430 before being beveled can be approximately 0.65 mm, and the height of the inner surface 432 after being beveled can be approximately 0.3 mm. Accordingly, the height h1 of the inclined portion 436 formed by beveling a portion of the inner surface 432 can be approximately 0.35 mm; for example, approximately 54% of the height h2 of the inner surface 432 can be beveled to form the inclined portion 436.

[0082] In one embodiment, based on a cross-sectional view of the pad 500 in the vertical direction (Y-axis), the vertical section of the inclined portion 436 can be formed to slope upward in a straight line. The angle of inclination of the inclined portion 436 can be determined according to the ratio of the inclined portion 436 to the oblique tangent areas of the lower surface 434 and the inner surface 432, and can be appropriately varied between approximately 20 degrees and 60 degrees.

[0083] According to one embodiment, when assembling a secondary battery, the second extension portion 430 can be positioned at a distance from the electrode assembly housed inside the housing. For example, the crimping portion can be formed by bending a side wall portion of the housing after the gasket 500 and the cover assembly are placed at one end of the housing housing housing the electrode assembly. In this case, as the side wall portion of the housing is bent, the gasket 500 is compressed, and the end portion of the second extension portion 430 can move downwards at an angle toward the electrode assembly. In this case, the flat surface of the inclined portion 436 formed in the second extension portion 430 is set to face the electrode assembly side, thereby minimizing interference between the second extension portion 430 and the electrode assembly. Furthermore, when the end portion of the second extension portion 430 moves downwards at an angle toward the electrode assembly, the end of the second extension portion 430 can be spaced more than a certain distance from the electrode assembly.

[0084] In one embodiment, when the crimping portion is bent to mate / secure the cover assembly and the gasket 500 to the sidewall portion of the housing, the thickness of the crimping portion can be managed in an upper limit mode, a normal mode, a lower limit mode, etc., depending on the compressibility of the gasket 500. In terms of increasing battery capacity, it may be advantageous to manage the thickness in the lower limit mode, which maximizes the compression ratio of the gasket 500 (e.g., a compression ratio of 50% or more for the gasket 500, or a mating thickness of the crimping portion of 2.4 mm or less). However, in this case, the variable of fire risk due to the sagging of the gasket 500 may need to be weighed. Accordingly, when considering process dispersion and other factors that occur during the bending process, even when managing the compression ratio of the gasket 500 in the lower limit mode, the end of the second extension 430 needs to be designed to be spaced at a predetermined distance from the electrode assembly.

[0085] For example, when the compression ratio of the pad 500 is managed in a lower limit mode, the distance between the end of the second extension 430 and the insulating plate disposed on the upper surface of the electrode assembly can be designed to be 0.3 mm or more. For example, when considering increasing battery capacity, the distance between the end of the second extension 430 and the insulating plate disposed on the upper surface of the electrode assembly can be designed to be 0.5 mm or less. That is, the distance between the end of the second extension 430 and the insulating plate disposed on the upper surface of the electrode assembly can preferably be designed to be 0.3 mm or more and 0.5 mm or less.

[0086] refer to Figure 5 The main body portion 410, the first extension portion 420, and the second extension portion 430 of the pad 500 are described separately, but this is only for the purpose of clearly describing the structure of the pad 500. The main body portion 410, the first extension portion 420, and the second extension portion 430 may be integrally formed, and the pad 500 may have an annular shape that is connected as a whole.

[0087] Figure 6 This is a partially enlarged view showing the shape of a pad 600 according to another embodiment of the present disclosure. Figure 6 It can be Figure 4 A magnified view of a portion of area C of the padding shown. (Referring to...) Figure 6 In the description, refer to Figure 1 Descriptions or repeated configurations are omitted.

[0088] In one embodiment, the pad 600 may include a generally cylindrical body portion 410, a first extension portion 420 extending from the body portion 410 in a generally vertical direction, and a second extension portion 430 extending downward at a predetermined angle from the first extension portion 410.

[0089] The second extension 430 may extend downward at a predetermined angle from the first extension 420, and may include an inner surface 432, a lower surface 434, an inclined portion 436, an upper inclined surface 437, and a lower inclined surface 438.

[0090] In one embodiment, a lower surface 434 and an inner surface 432 may be formed at the end portion of the second extension 430. The lower surface 434 of the second extension 430 may extend horizontally (X-axis) from a lower inclined surface 438, and the inner surface 432 may extend vertically (Y-axis) from an upper inclined surface 437.

[0091] In one embodiment, the inclined portion 436 may be formed between the lower surface 434 and the inner surface 432 of the second extension 430. The inclined portion 436 is formed by beveling at least a portion of the lower surface 434 and at least a portion of the inner surface 432 at the corner where the lower surface 434 and the inner surface 432 of the second extension 430 contact each other. Accordingly, the width w1 of the inclined portion 436 may be formed to be 30% to 70% of the width w2 of the lower surface 434 before being beveled. In addition, the height h1 of the inclined portion 436 may be 30% to 70% of the height h2 of the inner surface 432 before being beveled.

[0092] In one embodiment, based on a cross-sectional view of the pad 600 in the vertical direction (Y-axis), the vertical section of the inclined portion 436 can be formed to slope upward in a curved shape. For example, the inclined portion 436 can have a substantially convex arc shape in the direction in which the second extension 430 extends from the first extension 420.

[0093] With this configuration, when assembling the secondary battery, the arc-shaped inclined portion 436 can be positioned to face the electrode assembly side, thereby minimizing damage to the electrode assembly even when the second extension portion 430 of the pad 600 comes into contact with the electrode assembly due to the drooping of the second extension portion 430.

[0094] The shape of the inclined portion 436 can be varied, as long as the corners where the lower surface 434 and the inner surface 432 of the second extension portion 430 contact each other are removed.

[0095] Figure 7This is a diagram illustrating an example 700 of a pad 740 applied according to an embodiment of the present disclosure. In one embodiment, the pad 740 may include a body portion 742, a first extension portion 744 extending from the body portion 742, and a second extension portion 746 extending obliquely downward from the first extension portion 744. The second extension portion 746 may be configured to surround at least a portion of a coiled portion 726 formed in a housing. An electrode assembly may be disposed below the coiled portion 726, and the electrode assembly and an insulating plate disposed on the upper surface of the electrode assembly may be configured to be spaced further away from the lower line L1 of the coiled portion 726.

[0096] refer to Figure 7 Since the second extension 746 includes an inclined portion formed by beveling the lower surface and the inner surface, it can be seen that during the crimping process, even when the end portion of the second extension 746 moves downward at an angle, the end line L2 of the second extension 746 is formed above the lower line L1 of the coiled portion 726. In this case, the electrode assembly and insulating plate disposed below the lower line L1 of the coiled portion 726 do not contact or interfere with the second extension 746, thereby minimizing damage to the electrode assembly caused by the sag of the second extension 746.

[0097] Figure 8 This is a flowchart 800 of a method for manufacturing a secondary battery according to another embodiment of the present disclosure. The method for manufacturing a secondary battery can begin by preparing a cylindrical battery including a bottom portion, a sidewall portion connected to the bottom portion, and an upper opening portion facing the bottom portion (S810). Thereafter, an electrode assembly can be inserted into a housing (S820). Additionally, a rolled portion can be formed by bending the sidewall portion of the housing (S830).

[0098] Then, a gasket and cover assembly can be provided to seal the opening (S840). Here, the gasket may include a cylindrical body portion, a first extension portion extending from the body portion toward the interior of the housing, and a second extension portion extending obliquely downward from the first extension portion toward the bottom portion. Additionally, the cover assembly may include a top cover, a safety vent disposed below the top cover, and a bottom cover disposed below the safety vent and electrically connected to the electrode assembly. In this case, the gasket can insulate the housing from the safety vent and the top cover.

[0099] In one embodiment, the second extension may include an inclined portion formed by beveling the lower surface and the inner surface. In this case, the width w1 of the inclined portion may be 30% to 70% of the width w2 of the lower surface before the second extension is beveled. Additionally, the height h1 of the inclined portion may be 30% to 70% of the height h2 of the inner surface of the second extension before it is beveled. Furthermore, the vertical cross-section of the inclined portion may be a straight line. Alternatively, the vertical cross-section of the inclined portion may be a curve.

[0100] Then, a crimped portion can be formed by bending the end portion of the sidewall portion (S850). Forming the crimped portion may include bending the end portion of the sidewall portion such that at least a portion of the first extension portion and the second extension portion of the pad are in close contact with the crimped portion while the second extension portion moves downward at an angle toward the bottom portion.

[0101] In one embodiment, the insulating plate may be configured to contact the upper surface of the electrode assembly. Additionally, the second extension may be positioned at a predetermined distance from the insulating plate, with at least a portion of the second extension in close contact with the rolled portion. In this case, the distance between the second extension and the insulating plate may be 0.3 mm or more.

[0102] Figure 8 The flowcharts and descriptions above are merely examples of this disclosure, and the scope of this disclosure is not limited to... Figure 8 The flowchart and the above description. For example, one or more steps in the flowchart and / or the above description can be added, changed, or deleted; the order of one or more steps can be changed; and one or more steps can be executed simultaneously.

[0103] In summary, after the electrode assembly is inserted into the housing, the top of the housing can be bent over the electrode assembly to form a crimped portion. Subsequently, a gasket and cap assembly can be placed on the crimped portion, and a crimped portion can be formed by bending the end portion of the housing to secure the gasket and cap assembly. However, during the process of forming the crimped portion by bending the housing, the gasket may sag and interfere with the electrode assembly.

[0104] In contrast, an exemplary embodiment provides a secondary battery and a method of manufacturing the secondary battery, wherein the corners where the lower and inner surfaces of the second extension of the liner contact each other are beveled. Therefore, even when the second extension droops and its end portion moves downwards at an angle toward the bottom portion of the housing, interference between the electrode assembly and the second extension can be prevented.

[0105] According to some embodiments, the corners where the lower and inner surfaces of the second extension of the pad come into contact with each other are beveled and rounded, thereby minimizing damage to the electrode assembly even when the second extension comes into contact with the electrode assembly due to the sagging of the pad.

[0106] However, the aspects and features of this disclosure are not limited to those described above, and those skilled in the art will clearly understand from the above detailed description other aspects and features not mentioned.

[0107] Although this disclosure has been described above with reference to embodiments thereof, it is not limited thereto. Various modifications and variations can be made by those skilled in the art within the spirit of this disclosure and the equivalents of the appended claims.

[0108] This document has disclosed exemplary embodiments. Although specific terminology has been used, it is used and interpreted in a general and descriptive sense only and is not intended to be limiting. In some cases, as will be apparent to those skilled in the art at the time of filing this application, features, characteristics, and / or elements described in connection with particular embodiments may be used alone or in combination with features, characteristics, and / or elements described in connection with other embodiments, unless otherwise specifically stated. Accordingly, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims

1.A secondary battery comprising: an electrode assembly; a cylindrical case including a bottom portion, a side wall portion connected to the bottom portion, and an upper open portion facing the bottom portion, the cylindrical case accommodating the electrode assembly; a cap assembly coupled to the upper open portion; and a gasket between the cylindrical case and the cap assembly, the gasket including: a cylindrical main portion; a first extension portion extending from the cylindrical main portion toward an inside of the cylindrical case; and a second extension portion extending obliquely downward from the first extension portion toward the bottom portion of the cylindrical case, the second extension portion including a lower surface, an inner surface, and an inclined portion obliquely extending between and with respect to the lower surface and the inner surface. 2.The secondary battery of claim 1, wherein: an imaginary intersection of an extension line of the lower surface and an extension line of the inner surface defines an imaginary corner portion, and a first width of the lower surface to the extension line of the imaginary corner portion is 30% to 70% of a total width of the lower surface and the first width. 3.The secondary battery of claim 2, wherein a first height of the inner surface to the extension line of the imaginary corner portion is 30% to 70% of a total height of the inner surface and the first height. 4.The secondary battery of claim 1, wherein a vertical cross section of the inclined portion is in a form of a straight line. 5.The secondary battery of claim 1, wherein a vertical cross section of the inclined portion is in a form of a curve. 6.The secondary battery of any one of claims 1 to 5, wherein: the side wall portion of the cylindrical case includes a crimped portion formed by bending an end portion of the side wall portion, and a crimped portion bent inward from the side wall portion below the crimped portion, and the electrode assembly is accommodated below the crimped portion. 7.The secondary battery of claim 6, wherein: the cylindrical main portion of the gasket is in close contact with the crimped portion, and at least a portion of the first extension portion and the second extension portion of the gasket is in close contact with the crimped portion and surrounds at least a portion of an inner surface of the crimped portion. 8.The secondary battery of claim 7, further comprising an insulating plate on an upper surface of the electrode assembly, the second extension portion being at a predetermined distance from the insulating plate while at least a portion of the second extension portion is in close contact with the crimped portion. 9.The secondary battery of claim 8, wherein the predetermined distance is 0.3 mm or more. 10.The secondary battery of any one of claims 1 to 5, wherein the cap assembly includes an upper cap, a safety vent below the upper cap, and a lower cap below the safety vent, the lower cap being electrically connected to the electrode assembly. 11.The secondary battery of claim 10, wherein the gasket insulates the cylindrical case from the safety vent and the upper cap. ​ 12.A method of manufacturing a secondary battery, the method comprising: preparing a cylindrical case including a bottom portion, a side wall portion connected to the bottom portion, and an upper open portion facing the bottom portion; inserting an electrode assembly into the cylindrical case; forming a crimped portion by bending the side wall portion; providing a gasket and a cap assembly to seal the upper open portion; and forming a crimped portion by bending an end portion of the side wall portion, wherein: the gasket includes a cylindrical main portion, a first extension portion extending from the cylindrical main portion toward an inside of the case, and a second extension portion extending obliquely downward from the first extension portion toward the bottom portion, and the second extension portion includes an inclined portion formed by beveling a lower surface and an inner surface of the second extension portion. 13.The method of manufacturing a secondary battery according to claim 12, wherein a width of the inclined portion is 30% to 70% of a width of the lower surface of the second extension portion before being beveled. 14.The method of manufacturing a secondary battery according to claim 12, wherein a height of the inclined portion is 30% to 70% of a height of the inner surface of the second extension portion before being beveled. 15.The method of manufacturing a secondary battery according to claim 12, wherein a vertical cross section of the inclined portion is in a form of a straight line. 16.The method of manufacturing a secondary battery according to claim 12, wherein a vertical cross section of the inclined portion is in a form of a curved line. 17.The method of manufacturing a secondary battery according to any one of claims 12 to 16, wherein forming the crimped portion includes bending the end portion of the side wall portion such that at least a portion of the first extension portion and the second extension portion of the gasket are in close contact with the crimped portion while the second extension portion is obliquely moved downward toward the bottom portion. 18.The method of manufacturing a secondary battery according to claim 17, wherein: an insulating plate is provided to be in contact with an upper surface of the electrode assembly, and the second extension portion is provided at a predetermined distance from the insulating plate while at least a portion of the second extension portion is in close contact with the crimped portion. 19.The method of manufacturing a secondary battery according to claim 18, wherein the predetermined distance is 0.3 mm or more. 20.The method of manufacturing a secondary battery according to any one of claims 12 to 16, wherein: the cap assembly includes an upper cap, a safety vent provided below the upper cap, and a lower cap provided below the safety vent and electrically connected to the electrode assembly, and the gasket insulates the case from the safety vent and the upper cap. ​

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