Cylindrical secondary battery

Abstract

A cylindrical secondary battery includes: an electrode assembly; a can accommodating the electrode assembly; a cap assembly electrically connected to the electrode assembly, coupled to one side of the canister to close an inlet of the canister, and including an upper cap exposed to the outside; and a gasket between the cap assembly and the canister. The upper cover may include: a terminal portion having a circular shape; a base portion spaced apart from the terminal portion and surrounding an outer side of the terminal portion; and a plurality of bridge portions configured to connect the terminal portion to the base portion, and spaced apart from each other and having connection holes between the plurality of bridge portions. A width of a portion of each of the plurality of bridges connected to the terminal portion may be smaller than a width of a portion of each of the plurality of bridges connected to the base portion.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority and benefit of Korean Patent Application No. 10 - 2023 - 0194518, filed with the Korean Intellectual Property Office on December 28, 2023, the entire content of which is incorporated herein by reference. Technical field

[0003] Aspects of embodiments of the present disclosure relate to a cylindrical secondary battery having an improved lid assembly structure. Background art

[0004] Generally, a cylindrical secondary battery includes: a cylindrical electrode assembly; a cylindrical can configured to accommodate the electrode assembly and an electrolyte; and a lid assembly coupled to an upper opening of the can to seal the can and allow current generated in the electrode assembly to flow to an external device.

[0005] The lid assembly may include an upper lid, an exhaust plate, a lower lid, and an insulator between the exhaust plate and the lower lid. A notch that breaks when the internal pressure of the secondary battery increases is formed in the exhaust plate. The gas discharged through the notch is discharged to the outside of the secondary battery through a perforation provided in the upper lid. However, since the internal gas is discharged only through the perforation, when the internal pressure of the secondary battery increases, the gas may not be discharged quickly. In addition, when the structural stiffness of the upper lid is low, the shape of the upper lid may be deformed by an external force, blocking the perforation, and thus the gas may not be discharged smoothly.

[0006] The above information disclosed in the art used as the background of the present disclosure is only for improving the understanding of the background of the present disclosure, and thus may include information that does not constitute related art. Summary of the invention

[0007] Aspects of embodiments of the present disclosure relate to a cylindrical secondary battery having a lid assembly that can ensure a gas discharge flow path while maintaining a required compressive strength.

[0008] A cylindrical secondary battery according to an embodiment of the present disclosure may include: an electrode assembly; a can accommodating the electrode assembly; a lid assembly electrically connected to the electrode assembly, coupled to one side of the can to close an inlet of the can, and including an upper lid exposed to the outside; and a gasket between the lid assembly and the can.

[0009] In one or more embodiments, the upper cover may include: a terminal portion having a circular shape; a base portion spaced apart from the terminal portion and surrounding an outer side of the terminal portion; and a plurality of bridging portions configured to connect the terminal portion to the base portion, spaced apart from each other and having connection holes therebetween. A width of a portion of each of the plurality of bridging portions connected to the terminal portion may be less than a width of a portion of each of the plurality of bridging portions connected to the base portion.

[0010] In one or more embodiments, the width of the portion of the bridging portion connected to the terminal portion is an upper width, the width of the portion of the bridging portion connected to the base portion is a lower width, and a width of a central portion of the bridging portion is a central width, and the lower width may be greater than each of the upper width and the central width.

[0011] In one or more embodiments, the upper width may be greater than the central width.

[0012] In one or more embodiments, the central width may be greater than the upper width.

[0013] In one or more embodiments, a ratio I of the upper width to the lower width is defined as I = (upper width / lower width) × 100, and a value of the ratio I may be in a range of about 52 to about 68.

[0014] In one or more embodiments, a section in which the value of the ratio I is in a range of about 52 to about 56 is a first section, a section in which the value of the ratio I is in a range of about 57 to about 58 is a second section, and a stiffness of the upper cover in the first section may be lower than a stiffness in the second section.

[0015] In one or more embodiments, one of the bridging portions may include grooves on both sides of the bridging portion, and each groove faces the connection hole at one side of the bridging portion.

[0016] In one or more embodiments, when a curvature of each of the grooves increases, the central width may decrease, and when the curvature of each of the grooves decreases, the central width may increase.

[0017] In one or more embodiments, the bridging portions may be spaced apart from each other at the same angle.

[0018] In one or more embodiments, the lid assembly may further include: a lower lid below the upper lid; an exhaust plate between the upper lid and the lower lid; and an insulator between the exhaust plate and the lower lid.

[0019] A cylindrical secondary battery according to an embodiment of the present disclosure may include: a can having a cylindrical shape and an open upper side; an electrode assembly accommodated in the can together with an electrolyte; and a lid assembly coupled to an upper portion of the can, insulated from the can, electrically connected to the electrode assembly, and including an upper lid exposed to the outside.

[0020] In one or more embodiments, the upper lid may include: a terminal portion having a circular shape; a base portion spaced apart from the terminal portion, positioned below the terminal portion, and mounted in an annular shape; and a plurality of bridging portions configured to connect the terminal portion and the base portion, spaced apart from each other and having connection holes therebetween.

[0021] In one or more embodiments, a width of a portion of the bridging portion connected to the terminal portion is an upper width, a width of a portion of the bridging portion connected to the base portion is a lower width, and the lower width may be greater than the upper width.

[0022] In one or more embodiments, the cylindrical secondary battery may further include a gasket mounted between the lid assembly and the can, made of an insulating material, and surrounding an edge of the lid assembly.

[0023] In one or more embodiments, the can may include: a bottom having a circular shape; a side portion extending upward from an edge of the bottom; a crimping portion extending from the side portion and recessed inwardly above the electrode assembly to support a lower portion of the gasket; and a caulking portion extending upward from the crimping portion and bent inwardly to surround an upper portion of the gasket.

[0024] In one or more embodiments, the bridging portion may include grooves on both sides of the bridging portion, each groove facing the connection hole on one side of the bridging portion, a width of a portion of the bridging portion having the narrowest width is a center width, and a curvature of each groove and the center width may be inversely proportional to each other.

[0025] In one or more embodiments, the upper width may be greater than the center width. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a perspective view illustrating a cylindrical secondary battery according to an embodiment of the present disclosure.

[0027] Figure 2It is a cross-sectional view of a cylindrical secondary battery according to an embodiment of the present disclosure.

[0028] Figure 3 It is an example of a cross-sectional view of a cover assembly according to an embodiment of the present disclosure.

[0029] Figure 4 It is an example of a cross-sectional view of another embodiment of an exhaust plate according to an embodiment of the present disclosure.

[0030] Figure 5 It is an example of a perspective view of an upper cover according to an embodiment of the present disclosure.

[0031] Figure 6 It is a plan view of an upper cover according to an embodiment of the present disclosure.

[0032] Figures 7 to 9 It is an example of a plan view of a terminal portion and a bridging portion according to an embodiment of the present disclosure.

[0033] Figure 10 and Figure 11 It is an example of a view of a side groove formed in a bridging portion according to an embodiment of the present disclosure.

[0034] Figure 12 It is an example of a view of a structure in which an upper width of a bridging portion is greater than a center width of the bridging portion according to an embodiment of the present disclosure.

[0035] Figure 13 It is an example of a view of a structure in which a center width of a bridging portion is greater than an upper width according to an embodiment of the present disclosure. Detailed Description

[0036] Embodiments of the present disclosure are provided to more fully describe the present disclosure to those skilled in the art, and the following embodiments may be modified in many different forms, and the scope of the present disclosure is not limited to the following embodiments. On the contrary, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the spirit of the present disclosure to those skilled in the art.

[0037] In addition, in the following drawings, for convenience and clarity of illustration, the dimensions (e.g., thickness) of each layer are exaggerated, and like reference numerals in the drawings refer to like elements. As used in this specification, the term "and / or" may include any and all combinations of one or more of the associated listed items. Further, in this specification, it should be understood that when component A is referred to as being "connected to" component B, component A may be directly connected to component B, or component C may be interposed between component A and component B such that component A is indirectly connected to component B.

[0038] The terms used herein are for the purpose of describing particular embodiments and are not intended to limit the present disclosure. As used in this specification, the singular forms may include the plural forms unless the context clearly indicates otherwise. Further, when used in this specification, the terms "comprises" and / or "comprising" specify the presence of the described shapes, numbers, steps, operations, components, elements, and / or groups thereof, but do not preclude the presence or addition of one or more other shapes, numbers, steps, operations, components, elements, and / or groups thereof.

[0039] In this specification, although terms such as "first", "second", etc. may be used to describe various components, parts, regions, layers, and / or portions, these components, parts, regions, layers, and / or portions should not be limited by these terms. These terms are used to distinguish one component, part, region, layer, or portion from another component, part, region, layer, or portion. Thus, the first component, part, region, layer, or portion described below may also be referred to as the second component, part, region, layer, or portion without departing from the teachings of the present disclosure.

[0040] For ease of understanding the relationship between one element or feature illustrated in the drawings and another element or feature, spatial relative terms such as "under", "below", "beneath", "above", "on" may be used herein. These spatially relative terms are intended to facilitate understanding of the present disclosure according to various process states or usage states of the present disclosure and are not intended to limit the present disclosure. For example, when an element or feature in the drawings is flipped, an element or feature described as "under" or "below" may be changed to "above" or "on". Thus, the term "under" may encompass the terms "above" or "below".

[0041] Hereinafter, a cylindrical secondary battery 1 according to an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0042] Figure 1 is a perspective view illustrating a cylindrical secondary battery 1 according to an embodiment of the present disclosure, Figure 2 is a cross-sectional view of a cylindrical secondary battery 1 according to an embodiment of the present disclosure, Figure 3 is a cross-sectional view illustrating a cap assembly 400 according to an embodiment of the present disclosure, and Figure 4 is a cross-sectional view illustrating an exhaust plate 450' according to an embodiment of the present disclosure.

[0043] As Figures 1 to 4As shown in the figure, a cylindrical secondary battery 1 according to an embodiment of the present disclosure may include a can 100, an electrode assembly 200, and a cap assembly 400. In addition, the cylindrical secondary battery 1 may further include at least one of a negative electrode tab 300, a positive electrode tab 310, a first insulating plate 360, a second insulating plate 370, a center pin 380, and a gasket 500.

[0044] The can 100 that houses the electrode assembly 200 may have a cylindrical shape with an open upper side (e.g., an open upper end). The can 100 according to an embodiment of the present disclosure may include: a circular bottom 110; a side portion 130 extending upward from an edge (e.g., an outer peripheral edge) of the bottom 110; a crimping portion 132 extending inward from the side portion 130 and recessed inward at an upper portion of the electrode assembly 200 to support a lower portion of the gasket 500; and a caulking portion 134 extending upward from the crimping portion 132 and bent inward to surround an upper portion of the gasket 500.

[0045] The can 100 includes a circular bottom 110 and a side portion 130 extending upward from the bottom 110. An opening is formed at an upper end or an upper part of the side portion 130. The can 100 may be formed of steel, a steel alloy, nickel-plated steel, a nickel-plated steel alloy, aluminum, an aluminum alloy, or an equivalent thereof, but the present disclosure is not limited to these materials. The cap assembly 400 is inserted through the opening of the can 100. The crimping portion 132 and the caulking portion 134 may be formed on the side portion 130 such that the inserted cap assembly 400 is held and does not separate to the outside through the opening of the can 100.

[0046] The crimping portion 132 is located at a lower portion of the cap assembly 400 and is recessed in a direction toward the inside of the can 100. The gasket 500 may be located between the crimping portion 132 and the cap assembly 400.

[0047] The caulking portion 134 may extend from the crimping portion 132 and surround an upper portion of the cap assembly 400. The gasket 500 may be located between the caulking portion 134 and the cap assembly 400. The caulking portion 134 is bent in a direction toward the inside of the can 100. The crimping portion 132 and the caulking portion 134 restrict the downward and upward movement of the cap assembly 400 such that the cap assembly 400 does not separate from the can 100. In addition, in the secondary battery manufacturing process, the electrode assembly 200 may be accommodated in the can 100 together with an electrolyte through the opening of the can 100.

[0048] The electrode assembly 200 accommodated in the can 100 together with the electrolyte may be formed in various shapes. The electrode assembly 200 according to an embodiment of the present disclosure includes a negative electrode plate 210, a positive electrode plate 220, and a separator 230.

[0049] The negative electrode active material can be formed on both surfaces of the negative electrode plate 210. In one or more embodiments, the negative electrode active material can be graphite, carbon, etc. The positive electrode active material can be formed on both surfaces of the positive electrode plate 220. In one or more embodiments, the positive electrode active material can be made of a transition metal oxide, and the transition metal oxide can include, for example, LiCoO2, LiNiO2, LiMn2O4, etc.

[0050] The separator 230 is located between the negative electrode plate 210 and the positive electrode plate 220 to prevent short circuits and allow the movement of lithium ions. The negative electrode plate 210, the positive electrode plate 220, and the separator 230 can be wound into a substantially cylindrical shape and accommodated inside the can 100.

[0051] In one or more embodiments, the negative electrode plate 210 can be made of copper (Cu) foil or nickel (Ni) foil, the positive electrode plate 220 can be made of aluminum (Al) foil, and the separator 230 can be made of polyethylene (PE) or polypropylene (PP), but the present disclosure is not limited to these materials.

[0052] In one or more embodiments, the negative electrode tab 300 can protrude a predetermined length below the negative electrode plate 210 and can be fixed to the negative electrode plate 210 by welding. In one or more embodiments, the positive electrode tab 310 can protrude a predetermined length above the positive electrode plate 220 and can be fixed to the positive electrode plate 220 by welding. In one or more embodiments, the mounting positions of the negative electrode tab 300 and the positive electrode tab 310 can be interchanged.

[0053] The negative electrode tab 300 can be made of copper or nickel material, and the positive electrode tab 310 can be made of aluminum material, but the present disclosure is not limited to these materials. The negative electrode tab 300 can be welded to the bottom 110 of the can 100 so that the can 100 can operate as a negative electrode. In one or more embodiments, the positive electrode tab 310 can be welded to the bottom 110 of the can 100 so that the can 100 can operate as a positive electrode. In Figures 1 to 4 the illustrated embodiment, the negative electrode tab 300 is welded to the bottom 110 of the can 100.

[0054] In addition, the first insulating plate 360 and the second insulating plate 370 can be located at the lower and upper portions of the electrode assembly 200, respectively. The first insulating plate 360 prevents (or at least reduces) electrical contact between the positive electrode plate 220 and the bottom 110 of the can 100, and the second insulating plate 370 prevents (or at least reduces) electrical contact between the negative electrode plate 210 and the lid assembly 400.

[0055] A first hole 362 (e.g., a lower hole) communicating with the center pin 380 and a second hole 364 allowing the negative electrode tab 300 to pass through are provided in a first insulating plate 360 located at the lower part of the electrode assembly 200. Each of the first hole 362 and the second hole 364 has a hole shape passing through the first insulating plate 360 in the vertical direction.

[0056] When a large amount of gas is generated due to an abnormality in the secondary battery 1, the first hole 362 guides the large amount of gas to move upward through the cylindrical center pin 380. The negative electrode tab 300 can be welded to the bottom 110 of the can 100 through the second hole 364.

[0057] A first hole 372 (e.g., an upper hole) is provided in a second insulating plate 370 located at the upper part of the electrode assembly 200. When a large amount of gas is generated due to an abnormality in the secondary battery, the first hole 372 allows the large amount of gas to move to the lid assembly 400. In addition, a second hole 374 allowing the positive electrode tab 310 to pass through can be provided in the second insulating plate 370. Each of the first hole 372 and the second hole 374 has a hole shape passing through the second insulating plate 370 in the vertical direction.

[0058] The positive electrode tab 310 can be welded to a lower lid 460 to be described below through the second hole 374. A plurality of second holes 374 can be formed to serve as inlets through which the electrolyte is injected into the electrode assembly 200 during the electrolyte injection process.

[0059] In one or more embodiments, other current collecting structures can be used in the secondary battery of the present embodiment. In one or more embodiments, current collecting plates respectively electrically connected to the uncoated portion of the negative electrode and the uncoated portion of the positive electrode can be provided, wherein the uncoated portion of the negative electrode and the uncoated portion of the positive electrode on which no active material is coated are respectively formed on the negative electrode plate 210 and the positive electrode plate 220. The current collecting plates can be provided at the positions of the above-mentioned insulating plates. In one or more embodiments, the negative electrode current collecting plate can be electrically connected to the can 100, and the positive electrode current collecting plate can be electrically connected to the lid assembly and insulated from the can 100.

[0060] The electrode assembly 200 can be supported by the center pin 380. The center pin 380 can be a hollow circular tube and can be coupled to the approximate center of the electrode assembly 200. The center pin 380 can be formed of steel, steel alloy, nickel-plated steel, nickel-plated steel alloy, aluminum, aluminum alloy or polybutylene terephthalate, but the present disclosure is not limited to these materials. The center pin 380 is used to suppress the deformation of the electrode assembly 200 during charging and discharging of the secondary battery 1 and serves as a path through which the gas generated inside the secondary battery moves. In one or more embodiments, the center pin 380 can be omitted.

[0061] The lid assembly 400 is electrically connected to the electrode assembly 200 and is coupled to one side of the can 100 to close (e.g., seal) the inlet of the can 100. The lid assembly 400 is coupled to the upper part of the can 100 and is insulated from the can 100. In one or more embodiments, the lid assembly 400 may include an upper lid 410 that is exposed to the outside.

[0062] The lid assembly 400 according to one embodiment of the present disclosure may include an upper lid 410 that is exposed to the outside of the can 100, a lower lid 460 below the upper lid 410, an exhaust plate 450 between the upper lid 410 and the lower lid 460, and an insulator 470 between the exhaust plate 450 and the lower lid 460. In Figure 2 it, the direction facing the center pin 380 is defined as the inward direction, and the direction away from the center pin 380 is defined as the outward direction.

[0063] The upper lid 410 protrudes above the upper lid assembly 400 and serves as a terminal. In one or more embodiments, the upper lid 410 is located at the uppermost part of the upper lid assembly 400 and may include a terminal portion 411, a base portion 412, a bridging portion 420, and a connection hole 430 through which the gas generated inside the can 100 is discharged to the outside.

[0064] The upper lid 410 may have a generally disk shape with a predetermined area that protrudes upwardly around its central axis. The central axis may be a virtual line that passes vertically through the terminal center point C to be described below.

[0065] At least one connection hole 430 may be formed at the boundary between the disk portion and the protruding portion. The remaining portion where the connection hole 430 is not formed may be defined as a bridge. The detailed structure of the upper lid 410 will be described below. The exhaust plate 450 may be below the upper lid 410, and the exhaust plate 450 may surround the edge of the upper lid 410.

[0066] The exhaust plate 450 is between the upper lid 410 and the lower lid 460 and is electrically connected to the upper lid 410. The exhaust plate 450 has a generally disk shape with an edge that is bent upward toward the edge of the upper lid 410 and contacts the lower part of the edge of the upper lid 410. The exhaust plate 450 may be bent again toward the inside of the can 100 at the portion in contact with the upper lid 410 such that the exhaust plate 450 contacts the upper part of the edge of the upper lid 410.

[0067] According to one embodiment of the present disclosure, the exhaust plate 450 may include an exhaust bottom portion 452, a first support portion 454, a second support portion 456, and a contact portion 458. The unbent disk portion of the exhaust plate 450 is defined as the exhaust bottom portion 452, the portion of the exhaust plate 450 bent upward from the exhaust bottom portion 452 toward the upper cover 410 is defined as the first support portion 454, and the portion of the exhaust plate 450 bent inward from the first support portion 454 is defined as the second support portion 456. The second support portion 456 surrounds the edge of the upper cover 410.

[0068] The portion protruding convexly downward from the exhaust bottom portion 452 and contacting the lower cover 460 is defined as the contact portion 458. The exhaust plate 450 is formed such that all regions except the contact portion 458 do not contact the lower cover 460. At least one notch 452a may be formed in the exhaust bottom portion 452 of the exhaust plate 450. In one or more embodiments, the notch 452a may be formed in a circular shape in the exhaust bottom portion 452.

[0069] In one or more embodiments, as Figure 4 shown, notches 452a' may be formed in the exhaust bottom portion 452', and may be formed corresponding to the positions of the bridging portions 420 of the upper cover 410 to be described below. At least some or all of the notches 452a' may be formed corresponding to the positions of the bridging portions 420 of the upper cover 410. When the gas pressure inside the can 100 is greater than a predetermined rupture pressure, the notches 452a' may break when the exhaust plate 450 is inverted in the upward direction. Accordingly, the gas inside the can 100 can be quickly discharged to the outside through the connection holes 430 of the upper cover 410.

[0070] The lower cover 460 is below the upper cover 410. The lower cover 460 is below the exhaust plate 450 and has a substantially disk shape. In one or more embodiments, the lower cover 460 may be formed of aluminum, aluminum alloy, and / or equivalents thereof, but the present disclosure is not limited to these materials. The lower cover 460 is used to support the upper cover 410 to prevent (or at least mitigate) the upper cover 410 from deforming due to external forces.

[0071] The lower cover 460 according to one embodiment of the present disclosure includes a lower cover bottom portion 464 and a third support portion 462, and perforations 464a may be provided in the lower cover bottom portion 464. The edge of the lower cover 460 is bent toward the exhaust plate 450 to form the third support portion 462. An insulator 470 is between the third support portion 462 and the exhaust plate 450.

[0072] The unbent disk portion of the lower cover 460 is defined as the lower cover bottom portion 464, and the lower cover bottom portion 464 is spaced apart from the exhaust bottom portion 452 of the exhaust plate 450 by a set separation distance (e.g., a gap). The approximate center portion of the lower cover bottom portion 464 contacts the contact portion 458 of the exhaust plate 450. Perforations 464a through which gas moves can be formed in the lower cover bottom portion 464. Thus, the internal gas can be discharged to the outside of the can 100 via the perforations 464a of the lower cover 460, the notches 452a of the exhaust plate 450, and the connection holes 430 of the upper cover 410.

[0073] The insulator 470 is between the exhaust plate 450 and the lower cover 460, and is an insulating member that blocks the movement of electricity (electric current). The insulator 470 serves as a spacer such that the exhaust plate 450 and the lower cover 460 can be kept spaced apart except at the contact portion 458.

[0074] The insulator 470 is made of an insulating material that prevents the exhaust plate 450 and the lower cover 460 from being electrically connected to each other except at the contact portion 458. When viewed from above, the insulator 470 can be formed in an annular shape having a predetermined width. In one or more embodiments, the insulator 470 can be formed of polyethylene (PE), polypropylene (PP), polystyrene (PS), ethylene-vinyl acetate copolymer (EVA), or the like, but the present disclosure is not limited thereto. The insulator 470 can be coupled to the exhaust plate 450 and the lower cover 460 by ultrasonic welding, laser welding, fusion, or the like.

[0075] The gasket 500 between the can 100 and the lid assembly 400 is made of an insulating material that blocks electrical connection. Since the gasket 500 is installed (located) between the lid assembly 400 and the can 100, the lid assembly 400 and the can 100 are prevented from being electrically connected to each other. The gasket 500 according to an embodiment of the present disclosure is installed (located) between the lid assembly 400 and the can 100 and surrounds the edge of the lid assembly 400.

[0076] In the secondary battery 1 having the above-described configuration, the upper cover 410 can have a compressive strength such that the upper cover 410 is configured not to block the connection holes 430 that serve as gas discharge flow paths when pressure is applied from the outside.

[0077] When the compressive strength of the upper cover 410 is too low, all the bridging portions 420 may break when the internal gas is discharged, which is advantageous for gas discharge. However, when pressure is applied from the outside, the upper cover 410 may be distorted, blocking the connection holes 430 that serve as gas discharge flow paths, thereby preventing gas discharge.

[0078] When the compressive strength of the upper cover 410 is too high, the bridging portion 420 may not break during gas discharge inside the secondary battery. Therefore, since gas is discharged only through the connection hole 430, it may be difficult to quickly discharge the internal gas. Accordingly, in order to quickly discharge the internal gas while appropriately maintaining the compressive strength of the upper cover 410, the bridging portion 420 can be cut to provide an additional flow path.

[0079] Accordingly, in the upper cover 410 according to an embodiment of the present disclosure, the width of the bridging portion 420 can be selected such that the secondary battery 1 can provide an internal gas discharge flow path while maintaining sufficient compressive strength of the upper cover 410.

[0080] Hereinafter, the structure of the upper cover 410 according to various embodiments of the present disclosure will be described in detail.

[0081] Figure 5 is a perspective view illustrating an upper cover 410 according to an embodiment of the present disclosure, Figure 6 is a plan view of an upper cover 410 according to an embodiment of the present disclosure. As Figure 5 and Figure 6 shown, the upper cover 410 according to an embodiment of the present disclosure includes a terminal portion 411, a base portion 412, a bridging portion 420, and a connection hole 430.

[0082] The terminal portion 411 may have a circular shape, such as a circular plate shape. The terminal portion 411 is electrically connected to the electrode assembly 200 and may protrude outward from the cover assembly 400. The terminal portion 411 may be a disk or a plate formed in various shapes. The terminal portion 411 and the exhaust plate 450 may be electrically connected to each other, the exhaust plate 450 and the lower cover 460 may be electrically connected to each other, and the lower cover 460 and the electrode assembly 200 may be electrically connected to each other.

[0083] The base portion 412 is spaced apart from the terminal portion 411 and is positioned lower than the terminal portion 411. In one or more embodiments, the base portion 412 may have an annular shape. The base portion 412 according to an embodiment of the present disclosure is spaced apart from the terminal portion 411 and has a shape surrounding the outer side of the terminal portion 411. The center of the terminal portion 411 is referred to as the terminal center point C (see Figure 6 ), and the base portion 412 may extend in an arc direction around the terminal center point C. A circular hole may be formed in the center of the base portion 412, and the terminal portion 411 may be located above the circular hole. The terminal portion 411 and the base portion 412 are connected to each other by the bridging portion 420.

[0084] The bridging part 420 connects the terminal part 411 to the base part 412, and they are spaced apart from each other and have connection holes 430 therebetween (e.g., one connection hole 430 between each pair of adjacent bridging parts 420). A plurality of bridging parts 420 are formed, with the upper side of each bridging part 420 connected to the terminal part 411 and the lower side of each bridging part 420 connected to the base part 412.

[0085] In one or more embodiments, the upper cover 410 may include two or more bridging parts 420, and the bridging parts 420 may be spaced apart from each other at the same (or substantially the same) angle. In one or more embodiments where the upper cover 410 includes three bridging parts 420, each bridging part 420 may be spaced apart from each other at an interval of approximately 120°. However, the number of bridging parts 420 and the angular interval of the bridging parts 420 may be modified in various embodiments.

[0086] The bridging part 420 may have an upwardly inclined shape. The bridging part 420 may have a plate shape with a constant (or substantially constant) width. Each of the connection holes 430 through which gas moves is provided between adjacent bridging parts 420. Each of the connection holes 430 is located between the terminal part 411 and the base part 412 and is a hole extending in an arc direction around the terminal center point C.

[0087] In one or more embodiments of the present disclosure, side grooves (e.g., recesses) 425 are respectively provided on both sides of the bridging part 420 facing the connection hole 430. In one or more embodiments, the side grooves 425 may be formed only on one side or the other side of the bridging part 420. Additionally, in one or more embodiments, a plurality of side grooves 425 may be formed on one side of one of the bridging parts 420, and a single side groove 425 may be formed on the other side of that bridging part 420. In one or more embodiments, a single side groove 425 may be formed on one side of one of the bridging parts 420, and a plurality of side grooves 425 may be formed on the other side of that bridging part 420.

[0088] Figures 7 to 9 is a plan view illustrating the terminal part 411 and the bridging part 420 according to an embodiment of the present disclosure. As Figures 7 to 9 shown, the terminal part 411 and the base part 412 are connected together by the bridging part 420.

[0089] In one or more embodiments, the width of the part of the bridging part 420 connected to the terminal part 411 is defined as the upper width U1, and the width of the part of the bridging part 420 connected to the base part 412 is defined as the lower width D1. Additionally, in one or more embodiments, the width of the part of the bridging part 420 having the narrowest width is defined as the center width C1.

[0090] The upper portion of each bridging portion 420 is connected to the terminal portion 411. Thus, the length of the upper portion of the bridging portion 420 that is connected to the terminal portion 411 is referred to as the upper width U1. The portion of the bridging portion 420 that is connected to the terminal portion 411 extends in the arc direction, but for ease of description, this portion will be described as extending in the left - right width direction. Thus, in one or more embodiments of the present disclosure, the upper width U1 may be defined as the length of the upper end of the bridging portion 420 in the width direction.

[0091] The lower portion of the bridging portion 420 is connected to the base portion 412. Thus, the length of the lower portion of the bridging portion 420 that is connected to the base portion 412 is referred to as the lower width D1. The portion of the bridging portion 420 that is connected to the base portion 412 extends in the arc direction, but for ease of description, this portion will be described as extending in the left - right width direction. Thus, in one or more embodiments of the present disclosure, the lower width D1 may be defined as the length of the lower end of the bridging portion 420 in the width direction.

[0092] In one or more embodiments, side grooves 425 are formed on both sides of the bridging portion 420. Thus, the center width C1 located at the center of the bridging portion 420 may be less than the upper width U1 and / or the lower width D1. Due to the shape of the side grooves 425, the position of the center width C1 may vary in the vertical direction. The side grooves 425 may be formed to have different curvatures or groove shapes at the upper and lower portions with respect to the portion where the center width C1 is formed.

[0093] In the upper cover 410 according to an embodiment of the present disclosure, the width of the portion of the bridging portion 420 that is connected to the terminal portion 411 may be less than the width of the portion of the bridging portion 420 that is connected to the base portion 412. That is, the upper width U1 may be less than the lower width D1. In one or more embodiments, the lower width D1 is greater than the upper width U1, so that the stiffness of the bridging portion 420 can be achieved, and when the internal pressure of the can 100 increases, the bridging portion 420 ruptures around the portion having the upper width U1, so that gas can be discharged quickly.

[0094] In the upper cover according to an embodiment of the present disclosure, the lower width D1 may be greater than each of the upper width U1 and the center width C1. In one or more embodiments, the lower width D1 may be greater than the upper width U1, and the upper width U1 may be greater than the center width C1. Thus, the bridging portion 420 may break around the portion having the center width C1. In one or more embodiments, the upper width U1 may be greater than the center width C1. Thus, since the lower width D1 of the lower portion of the bridging portion 420 is greater than the upper width U1 and the center width C1, the bridging portion 420 can be stably supported.

[0095] Next, with reference to Figures 7 to 9 and Table 1 below, the ratio of the center width C1 to the lower width D1 for each angle of the connection hole 430 will be described.

[0096] [Table 1]

[0097]

[0098] As Figure 7 shown, in an embodiment where the upper width U1 of the bridging portion 420 is approximately 3.91 mm, its center width C1 is approximately 3.44 mm, and its lower width D1 is approximately 4.91 mm, the first angle A1 as the angle of the connection hole 430 is approximately 80°. The angle of the connection hole 430 is the angle around the terminal center point C between one end of the connection hole 430 in contact with the bridging portion 420 and the other end. The value obtained by subtracting the center

[0099] width C1 from the lower width D1 is 1.47 mm, and the ratio of the center width C1 to the lower width D1 is approximately 70%. The ratio of the center width C1 to the lower width D1 is referred to as I, and I is defined as I = (center width C1 / lower width D1) × 100. In one or more embodiments, the value of the ratio I is 70. As Figure 8 shown, in an embodiment where the upper width U2 of the bridging portion 421 is approximately 3.19 mm, its center width C2 is approximately 2.68 mm, and its lower width D2 is approximately 4 mm, the second angle A2 as the angle of the connection hole 431 is approximately 90°. The value obtained by subtracting the center width C2 from the lower width D2 is approximately 1.32 mm, and the ratio (I) of the center width C2 to the lower width D2 is approximately 67%.

[0100] As Figure 9 shown, in an embodiment where the upper width U3 of the bridging portion 422 is approximately 2.44 mm, its center width C3 is approximately 1.8 mm, and its lower width D3 is approximately 3.05 mm, the third angle A3 as the angle of the connection hole 432 is approximately 100°. The value obtained by subtracting the center width C3 from the lower width D3 is approximately 1.25 mm, and the ratio (I) of the center width C3 to the lower width D3 is approximately 59%.

[0101] As Figures 7 to 9As shown, in embodiments where the area of the terminal portion 411 is the same, the lower width D1 is formed to have a maximum value, followed by the upper width U1 and the center width C1. Further, in embodiments where the ratio of the center width C1 to the lower width D1 is in the range of approximately 57% to approximately 59%, deformation of the bridging portion 420 can be prevented during normal use of the bridging portion 420, and in an emergency, the bridging portion 420 can be caused to break to rapidly discharge gas.

[0102] Differences according to changes in the ratio of the upper width U1 to the lower width D1 of the bridging portion 420 will be described below with reference to Table 2.

[0103] [Table 2]

[0104]

[0105]

[0106] As shown in Table 2, the bridging portion 420 can be configured such that the ratio of the upper width U1 to the lower width D1 is in the range of approximately 52% to approximately 68%, and the value of the lower width D1 is fixed. The ratio of the upper width U1 to the lower width D1 is referred to as I, and I is defined as I = (upper width U1 / lower width D1) × 100. In one or more embodiments, the value of the ratio I can be in the range of approximately 52 to approximately 68. In one or more embodiments, the section where the value of the ratio I of the bridging portion 420 is in the range of approximately 52 to approximately 56 is referred to as the first section, and the section where the value of the ratio I is in the range of approximately 57 to approximately 58 is referred to as the second section, and the upper cover 410 can exhibit reduced stiffness in the first section compared to the second section.

[0107] In one or more embodiments where the value of the ratio I is in the range from approximately 52 to approximately 68, under normal conditions, the bridging portion 420 can remain undeformed or can be slightly deformed. In an emergency where the gas pressure inside the tank 100 increases, the bridging portion 420 can break due to the gas pressure.

[0108] In the first section where the value of the ratio I is in the range of approximately 52 to approximately 56, the upper width U1 is less than the lower width D1, and thus, the possibility of deformation or rupture at the portion having the center width C1 or the upper width U1 is high.

[0109] In a second section where the value of ratio I ranges from approximately 57 to approximately 58, the upper width U1 is relatively large compared to the first section. Therefore, the possibility of deformation or rupture at the portion with the center width C1 or the upper width U1 is lower than that of the first section. However, since even in the second section the upper width U1 is smaller than the lower width D1, when the internal gas pressure is greater than the set gas pressure, deformation or rupture occurs at the upper width U1 or the center width C1, allowing the gas to be discharged quickly.

[0110] When the value of ratio I is greater than or equal to 72, the stiffness of the bridging portion 420 increases. Therefore, the bridging portion 420 may not even deform or be cut off due to gas pressure, and the gas generated inside the tank 100 may not be quickly discharged to the outside of the upper cover 410, increasing the risk of safety accidents. Thus, in one or more embodiments, the value of ratio I may not be greater than or equal to approximately 72.

[0111] In addition, since the stiffness of the bridging portion 420 is too weak when the value of I is less than or equal to approximately 48, the bridging portion 420 may be prone to deformation even during normal use and may block the connection hole 430, making it difficult to discharge the gas generated inside the tank 100. Therefore, in one or more embodiments, the value of ratio I may not be less than or equal to approximately 48.

[0112] The unit of ratio I may be %, and the unit of ratio I may vary as needed.

[0113] Figure 10 and Figure 11 is a view showing side grooves 425, 426 formed in the bridging portion 420 according to an embodiment of the present disclosure. As Figure 10 shown, along the direction in which the curvature of the side groove 425 increases, the center width C1 may decrease, and along the direction in which the curvature of the side groove 423 decreases, the center width C1 may increase.

[0114] In an embodiment where the width of the portion of the bridging portion 420 having the narrowest width is referred to as the center width C1, the curvature of the side groove 425 and the center width C1 may be inversely proportional to each other. In another embodiment of the present invention, the center width C1 may be the width of the portion located at the center of the bridging portion 420.

[0115] Figure 10 The curvature of the side groove 425 shown may be greater than Figure 11 the curvature of the side groove 426 shown. In addition, in Figure 10 an embodiment where the lower width D1 shown is the same (or substantially the same) as Figure 11 the lower width D1 shown, Figure 10 the center width C1 shown may be greater than Figure 11The central width C3 shown. In addition, Figure 10 the upper width U1 shown may be greater than Figure 11 the upper width U3 shown.

[0116] The stiffness of the bridging portion 420 may be adjusted according to the curvature of the side grooves 425, 426. In an embodiment where the curvature of the side groove 426 is small, the central width C1 increases, so that the stiffness of the bridging portion 420 increases. In addition, in an embodiment where the curvature of the side groove 425 is large, the central width C1 decreases, so that the stiffness of the bridging portion 420 increases. Curvature and radius of curvature have an inverse relationship.

[0117] Figure 12 is a view illustrating a state in which the upper width U1 of the bridging portion 420 according to an embodiment of the present disclosure is greater than the central width C1. As Figure 12 shown, in an embodiment where the lower width D1, the upper width U1, and the central width C1 of the bridging portion 420 gradually decrease in this order, the side groove 425 facing the connection hole 430 may be formed as a groove having a radius of curvature. That is, the side groove 425 facing the connection hole 430 may be formed as a groove having a radius of curvature.

[0118] Figure 13 is a view illustrating a structure in which the central width C1 of the bridging portion 420 according to an embodiment of the present disclosure is greater than the upper width U4. As Figure 13 shown, in an embodiment where the lower width D1, the central width C1, and the upper width U4 of the bridging portion 420 gradually decrease in this order, the side groove 425 located on the upper side of the portion having the central width C1 may be formed with a bent portion, and the side groove 425 located on the lower side of the portion having the central width C1 may be formed as a straight line. In this embodiment, the lower width D1 may be greater than the central width C1, and the central width C1 may be greater than the upper width U4.

[0119] As described above, the compressive strength of the upper cover 410 can be adjusted by adjusting the upper width U1, the central width C1, and the lower width D1 of the bridging portion 420 provided in the upper cover 410, thereby ensuring a gas discharge flow path. In addition, the reliability of the passive propagation resistance (PPR) test results can be improved, and the safety of the cylindrical secondary battery 1 can be improved. PPR in a secondary battery is a technology for improving the safety of the entire battery pack by controlling the spread of an abnormal event (e.g., thermal runaway) in a secondary battery to adjacent battery cells even when the abnormal event starts in one battery cell.

[0120] According to an embodiment of the present disclosure, the compressive strength of the upper cover can be adjusted by adjusting the upper width, the central width, and the lower width of the bridging portion provided in the upper cover, thereby ensuring a gas discharge flow path.

[0121] In addition, the reliability of the passive propagation resistance (PPR) test results can be improved, and the safety of the cylindrical secondary battery can be improved.

[0122] The above description is only an embodiment for implementing the present disclosure, and the present disclosure is not limited to the above embodiment. As claimed, the technical spirit of the present disclosure will be considered to the extent that various modifications can be made by those skilled in the art without departing from the gist of the present disclosure.

Claims

1. A cylindrical secondary battery, comprising: Electrode assembly; a tank accommodating the electrode assembly; a cap assembly electrically connected to the electrode assembly and coupled to one side of the can to close an inlet of the can, the cap assembly comprising an upper cover exposed to the outside; as well as a gasket, between the cap assembly and the can, The upper cover comprises: a terminal portion having a circular shape; a base portion spaced apart from the terminal portion and surrounding an outer side of the terminal portion; and a plurality of bridge portions configured to connect the terminal portion to the base portion, the plurality of bridge portions being spaced apart from each other and having connection holes between the plurality of bridge portions, and A width of a portion of each of the plurality of bridge portions connected to the terminal portion is smaller than a width of a portion of each of the plurality of bridge portions connected to the base portion.

2. A cylindrical secondary battery according to claim 1, wherein the width of the portion of each bridge portion connected to the terminal portion is an upper width, the width of the portion of each bridge portion connected to the base portion is a lower width, the width of the central portion of each bridge portion is a central width, and the lower width is greater than each of the upper width and the central width. 3 . The cylindrical secondary battery according to claim 2 , wherein the upper width is greater than the center width. The cylindrical secondary battery according to claim 2 , wherein the center width is greater than the upper width. 5 . The cylindrical secondary battery according to claim 2 , wherein a ratio I of the upper width to the lower width is defined as I=(the upper width / the lower width)×100, and wherein a value of the ratio I is in the range of 52 to 68.

6. A cylindrical secondary battery according to claim 5, wherein a segment in which the value of the ratio I is in the range of 52 to 56 is a first segment, a segment in which the value of the ratio I is in the range of 57 to 58 is a second segment, and the stiffness of the upper cover in the first segment is lower than that in the second segment. 7 . The cylindrical secondary battery according to claim 2 , wherein a bridge portion of the plurality of bridge portions includes grooves on both sides of the bridge portion, and wherein each of the grooves faces the connection hole at one of the sides of the bridge portion.

8. The cylindrical secondary battery according to claim 7, wherein the center width decreases as the curvature of each of the grooves increases, and Wherein, when the curvature of each of the grooves decreases, the central width increases.

9. The cylindrical secondary battery according to any one of claims 1 to 8, wherein The plurality of bridge portions are spaced apart from each other at the same angle.

10. The cylindrical secondary battery according to any one of claims 1 to 8, wherein the cap assembly further comprises: a lower cover, below the upper cover; An exhaust plate, between the upper cover and the lower cover; and An insulator is between the exhaust plate and the lower cover.

11. A cylindrical secondary battery comprising: a tank, having a cylindrical shape and an open upper side; an electrode assembly housed in the tank together with an electrolyte; as well as a cap assembly coupled to the upper side of the can, insulated from the can, electrically connected to the electrode assembly, and including an upper cover exposed to the outside, The upper cover comprises: a terminal portion having a circular shape; a base portion that is spaced apart from the terminal portion, is positioned lower than the terminal portion, and has a ring shape; and a plurality of bridge portions configured to connect the terminal portion to the base portion, the plurality of bridge portions being spaced apart from each other and having connection holes between the plurality of bridge portions, and The width of a portion of each of the plurality of bridge portions connected to the terminal portion is an upper width, the width of a portion of each of the plurality of bridge portions connected to the base portion is a lower width, and the lower width is greater than the upper width. 12 . The cylindrical secondary battery according to claim 11 , further comprising a gasket between the cap assembly and the can, wherein the gasket comprises an insulating material, and wherein the gasket surrounds an edge of the cap assembly.

13. The cylindrical secondary battery according to claim 12, wherein the can comprises: The bottom portion, having a rounded shape; a side portion extending upwardly from an edge of the base; a curling portion extending from the side portion and recessed inwardly at an upper portion of the electrode assembly to support a lower portion of the gasket; and The crimping portion extends upward from the crimping portion and is bent inwardly and surrounds the upper portion of the gasket.

14. The cylindrical secondary battery according to claim 11, wherein each of the bridge portions comprises grooves on both sides of each of the bridge portions, wherein each of the grooves faces the connection hole along one of the sides of each of the bridge portions, and The width of a portion having the narrowest width of each bridge portion is a central width, and the curvature of each groove and the central width are inversely proportional to each other. 15 . The cylindrical secondary battery according to claim 14 , wherein the upper width is greater than the center width.

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