Current collector and cylindrical secondary battery including same

Abstract

A cylindrical secondary battery according to an embodiment of the present invention may include an electrode assembly having an electrode tab, a battery can that houses the electrode assembly, a terminal that penetrates the battery can and is insulated from the battery can, and a current collecting plate that electrically connects the electrode tab and the terminal. The current collecting plate may include a rim portion, a terminal coupling portion located inside the rim portion and coupled to the terminal, a bridge connecting the rim portion and the terminal coupling portion, and a tab coupling portion extending inward from the rim portion, spaced apart from the bridge and the terminal coupling portion, and coupled to the electrode tab. An inner end of the tab coupling portion may have a reduced width as it approaches the terminal coupling portion.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0010936, filed on January 25, 2022, the entire contents of which are incorporated herein by reference. The present invention relates to a current collector plate and a cylindrical secondary battery including the same. [Background technology]

[0002] Conventional cylindrical secondary batteries generally have a structure in which a tab that connects a jelly roll to an external terminal is welded to the foil of the jelly roll. In cylindrical secondary batteries with this structure, the current path is limited, and the resistance of the jelly roll itself is inevitably very high.

[0003] For this reason, attempts have been made to reduce resistance by increasing the number of tabs connecting the jelly roll to the external terminals, but there is a limit to how much resistance can be reduced to the desired level and how much of a current path can be secured simply by increasing the number of tabs.

[0004] Therefore, in order to reduce the resistance of the jelly roll itself, it is necessary to develop a new jelly roll structure and a current collector plate structure suitable for such a jelly roll structure. In particular, the application of such a new jelly roll structure and current collector plate is even more necessary for devices that require a battery pack with high output / high capacity, such as electric vehicles.

[0005] In addition, in the case of battery packs applied to electric vehicles, etc., it is unavoidable that they are exposed to a lot of vibration and impact when considering the usage environment. Therefore, it is necessary to develop a cylindrical secondary battery having a structure that reduces the risk of damage to welded parts even when vibration and external impact are applied, and a current collector plate structure applicable to such a cylindrical secondary battery. Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a current collector having a structure suitable for an electrode assembly having a low resistance structure, and a cylindrical secondary battery including the current collector.

[0007] Another object of the present invention is to provide a current collector having a structure that can significantly reduce the possibility of damage occurring at a welded portion to an electrode assembly and / or a welded portion to a battery can even when vibration and impact are applied, and a cylindrical secondary battery including the current collector. [Means for solving the problem]

[0008] A cylindrical secondary battery according to an embodiment of the present invention may include an electrode assembly having an electrode tab, a battery can housing the electrode assembly, a terminal penetrating the battery can and insulated from the battery can, and a current collecting plate electrically connecting the electrode tab and the terminal. The current collecting plate may include a rim portion, a terminal coupling portion located inside the rim portion and coupling with the terminal, a bridge connecting the rim portion and the terminal coupling portion, and a tab coupling portion extending inward from the rim portion, spaced apart from the bridge and the terminal coupling portion, and coupling with the electrode tab. An inner end of the tab coupling portion may have a reduced width as it approaches the terminal coupling portion.

[0009] The bridges and the tab coupling portions may be arranged alternately in the circumferential direction of the current collector plate. The outer end of the bridge may have an increased width as it approaches the rim portion. The bridge may include a narrow portion having a relatively narrow width.

[0010] The width of the narrow portion may be 70% to 80% of the width of the bridge. The narrowing may be located closer to the outer ends of either end of the bridge. The distance from the center of the current collector plate to the narrow portion in the radial direction of the current collector plate may be 0.4 to 0.9 times the radius of the electrode assembly.

[0011] At least a portion of the electrode tab may be bent toward a central axis of the electrode assembly, and the narrow portion may face the bent portion of the electrode tab in the axial direction of the electrode assembly.

[0012] The narrow portion may be recessed at both side edges of the bridge or may be formed by penetrating the bridge. The width of the narrow portion may be narrower than the width of the rim portion.

[0013] The bridge may include a cover member surrounding the bridge and made of an insulating material having a lower thermal conductivity than the bridge. The cover member may include a polyimide (PI) material.

[0014] The width of the rim portion may be narrower than the width of the tab connection portion. The radius of the current collector plate may be 33% to 102% of the radius of the electrode assembly. The radius of the current collector plate may be 33% to 98.5% of the inner radius of the battery can.

[0015] The radius of the terminal coupling portion may be 40% to 320% of the radius of the main body portion of the terminal that is coupled to the terminal coupling portion. At least one opening may be formed between the rim portion and the terminal coupling portion, and the area of ​​the at least one opening may account for 40% to 99% of the total area of ​​the current collecting plate.

[0016] A current collecting plate according to an embodiment of the present invention may electrically connect an electrode assembly and a terminal penetrating a battery can in which the electrode assembly is housed. The current collecting plate may include a rim portion, a terminal coupling portion located inside the rim portion and coupled to the terminal, a bridge connecting the rim portion and the terminal coupling portion, and a tab coupling portion extending inward from the rim portion, spaced apart from the bridge and the terminal coupling portion, and coupled to an electrode tab provided on the electrode assembly. An inner end of the tab coupling portion may have a reduced width as it approaches the terminal coupling portion.

[0017] A cylindrical secondary battery according to an embodiment of the present invention may include an electrode assembly including a first electrode tab and a second electrode tab, a battery can housing the electrode assembly, a terminal penetrating the battery can and insulated from the battery can, a first current collecting plate electrically connecting the first electrode tab and the battery can, and a second current collecting plate electrically connecting the second electrode tab and the terminal. A difference between a bonding area between the first electrode tab and the first current collecting plate and a bonding area between the second electrode tab and the second current collecting plate may be three times or less.

[0018] A press-fitted beading portion may be formed between a cap plate and the electrode assembly at a periphery of the battery can, and a can coupling portion of the first current collector may be coupled to the beading portion.

[0019] The second current collecting plate may not overlap the beading portion in a height direction of the electrode assembly. The second current collecting plate may overlap the beading portion in a height direction of the electrode assembly, and a width of an area of ​​the beading portion that overlaps with the second current collecting plate may be 80% or less of a width of the beading portion. Effect of the Invention

[0020] According to a preferred embodiment of the present invention, the resistance in the electrical connection between the electrode assembly and the battery can can be significantly reduced.

[0021] In addition, even if vibrations and impacts are applied during use of the secondary battery, the possibility of damage occurring at the welded portion between the current collector plate and the electrode assembly and / or the welded portion between the current collector plate and the battery can can be significantly reduced. In addition, the present invention can include effects that can be easily predicted by a person skilled in the art from the configurations according to the preferred embodiments of the present invention. [Brief description of the drawings]

[0022] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical ideas of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters depicted in the drawings.

[0023] [Figure 1] 1 is a perspective view of a cylindrical secondary battery according to one embodiment of the present invention; [Diagram 2] 1 is a cutaway cross-sectional view of a cylindrical secondary battery according to an embodiment of the present invention; [Diagram 3] 3 is an enlarged cross-sectional view of a first current collector plate and its periphery shown in FIG. 2. [Figure 4] FIG. 2 is a perspective view of a first current collecting plate according to one embodiment of the present invention. [Diagram 5] 3 is an enlarged cross-sectional view of the second current collector plate and its periphery shown in FIG. 2. [Figure 6] FIG. 4 is a plan view of a second current collecting plate according to one embodiment of the present invention. [Figure 7] FIG. 7 is an enlarged view of the narrow portion shown in FIG. 6. [Figure 8] 7 is a diagram showing a modified example of the narrow portion shown in FIG. 6. [Figure 9] 7 is a diagram showing a state in which the narrow portion shown in FIG. 6 is surrounded by a cover member. [Figure 10] FIG. 11 is a plan view of a second current collecting plate according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in order to enable those skilled in the art to easily carry out the present invention. However, the present invention may be realized in various different forms, and is not limited to the following embodiments.

[0025] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related prior art that may unnecessarily obscure the gist of the present invention will be omitted, and when assigning reference symbols to components in each drawing in this specification, the same or similar reference symbols will be assigned to the same or similar components throughout the specification.

[0026] Furthermore, the terms and words used in this specification and the claims should not be interpreted in a limited manner to their ordinary or dictionary meanings, but should be interpreted in a manner that is consistent with the technical ideas of the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best describe their invention.

[0027] FIG. 1 is a perspective view of a cylindrical secondary battery according to one embodiment of the present invention, and FIG. 2 is a cut-away cross-sectional view of the cylindrical secondary battery according to one embodiment of the present invention. A cylindrical secondary battery 1 (hereinafter, “secondary battery”) according to one embodiment of the present invention can include an electrode assembly 10 and a battery can 20 that houses the electrode assembly 10.

[0028] The electrode assembly 10 may include a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. The electrode assembly 10 may also include a first electrode tab 11 connected to one of the positive electrode and the negative electrode, and a second electrode tab 12 connected to the other of the positive electrode and the negative electrode.

[0029] More specifically, the electrode assembly 10 may be of a jelly-roll type. The electrode assembly 10 may be manufactured by winding up a laminate in which a positive electrode, a separator, a negative electrode, and a separator are sequentially stacked. The electrode assembly 10 preferably has a height to diameter ratio of 1 or more, but is not limited thereto. A hollow (C) extending in the height direction may be formed in the center of the electrode assembly 10. A separator may be located on the outermost side of the electrode assembly 10 to insulate the electrode assembly 10 from the inner circumference of the battery can 20.

[0030] The first electrode tab 11 and the second electrode tab 12 may be provided at both ends in the height direction of the electrode assembly 10. More specifically, the uncoated portion of either the positive electrode or the negative electrode may be located at one end of the electrode assembly 10 and may function as the first electrode tab 11. The uncoated portion of the other of the positive electrode or the negative electrode may be located at the other end of the electrode assembly 10 and may function as the second electrode tab 12.

[0031] Each electrode tab 11 , 12 can extend along the winding direction of the electrode assembly 10 . Alternatively, each electrode tab 11 , 12 may include multiple foil-flags arranged along the winding direction of the electrode assembly 10 .

[0032] A first current collecting plate 50, which will be described later, may be coupled to the first electrode tab 11, and a second current collecting plate 60, which will be described later, may be coupled to the second electrode tab 12. The electrode assembly 10 may be housed in a battery can 20 with the current collecting plates 50, 60 coupled to the electrode tabs 11, 12, respectively.

[0033] For example, the first electrode tab 11 may be a negative uncoated portion, and the second electrode tab 12 may be a positive uncoated portion. In this case, the first current collector 50 may be named a negative current collector, and the second current collector 60 may be named a positive current collector.

[0034] The battery can 20 may have a substantially cylindrical shape. One side of the battery can 20 in the height direction may have one surface 20a, and the other side may have an opening.

[0035] The electrode assembly 10 can be housed in a battery can 20 together with an electrolyte through the opening. The battery can 20 may be made of a conductive material such as a metal. The battery can 20 may be electrically connected to the first electrode tab 11 via a first current collecting plate 50, which will be described later. The battery can 20 may have the same polarity as the first electrode tab 11.

[0036] The battery can 20 may have a beading portion 21 and a crimping portion 22. The beading portion 21 and the crimping portion 22 may be formed adjacent to an opening of the battery can 20.

[0037] The beading portion 21 can be formed by radially inwardly press-fitting the periphery of the battery can 20. The inner diameter of the beading portion 21 may be smaller than the inner diameter of the battery can 20.

[0038] The beading portion 21 may be formed in a state in which the electrode assembly 10 is accommodated in the battery can 20. The electrode assembly 10 may be constrained between one surface 20a of the battery can 20 and the beading portion 21 in the height direction of the battery can 20. The beading portion 21 may prevent the electrode assembly 10 from being detached to the opening of the battery can 20. In addition, the beading portion 21 may be coupled to the first current collecting plate 50. For example, the first current collecting plate 50 may be welded to the beading portion 21. As a result, the first current collecting plate 50 may electrically connect the first electrode tab 11 and the battery can 20.

[0039] The crimping portion 22 may be formed adjacent to the beading portion 21. The crimping portion 22 may be formed by bending an end of a peripheral surface of the battery can 20 radially inward. The crimping portion 22 may be formed after the first current collecting plate 50 is coupled to the beading portion 21. The crimping portion 22, together with the beading portion 21, may restrain a cap plate 30, which will be described later.

[0040] The secondary battery 1 may include a cap plate 30 that covers the open portion of the battery can 20 . The cap plate 30 may be in the shape of a substantially circular plate. The cap plate 30 can form the exterior of the secondary battery 1 together with the battery can 20. An edge portion of the cap plate 30 can be restrained between the beading portion 21 and the crimping portion 22 of the battery can 20.

[0041] The cap plate 30 may be made of a material having high rigidity such as metal. The cap plate 30 may be insulated from the battery can 20 and may not have polarity. More specifically, a seal portion 72 of a spacer 70, which will be described later, may be interposed between the cap plate 30 and the battery can 20. This will be described later.

[0042] The secondary battery 1 may include a terminal 40 that penetrates and is fixed to one surface 20 a of the battery can 20 . The terminal 40 may penetrate one surface 20a of the battery can 20, more specifically, the center of the one surface 20a. A portion of the terminal 40 may be exposed to the outside of the battery can 20, and another portion may be located inside the battery can 20. For example, the terminal 40 may be fixed to the one surface 20a of the battery can 20 by riveting.

[0043] The terminals 40 may be made of a conductive material such as a metal. The terminal 40 may be coupled to a second current collecting plate 60, which will be described later. For example, the second current collecting plate 60 may be welded to the terminal 40. In this way, the second current collecting plate 60 may electrically connect the second electrode tab 12 and the terminal 40.

[0044] The terminal 40 may be insulated from the battery can 20. More specifically, an insulating gasket (G) may be interposed between the terminal 40 and the battery can 20. However, without being limited thereto, an insulating coating layer may be formed on a part of the terminal 40, or the terminal 40 and the battery can 20 may be separated from each other, and in this case, a method of structurally fixing the terminal 40 may be applied.

[0045] The insulating gasket (G) can be deformed and bent toward the inner surface of one surface 20a of the battery can 20 when the terminal 40 is riveted. The insulating gasket (G) can seal the gap between the terminal 40 and the battery can 20.

[0046] Due to the insulating gasket (G), the battery can 20 and the terminal 40 may have opposite polarities. More specifically, the battery can 20 may have the same polarity as the first electrode tab 11, and the terminal 40 may have the same polarity as the second electrode tab 12. Thus, one surface 2a of the battery can 20 may function as a first terminal having a first polarity, and the terminal 40 may function as a second terminal having a second polarity. Since the one surface 2a of the battery can 20 and the terminal 40 are adjacent to each other, the internal space required for installation of a bus bar in a battery module including a plurality of secondary batteries 1 may be reduced, and the energy density of the battery module may be increased.

[0047] The secondary battery 1 may include a first current collector 50 that electrically connects the first electrode tab 11 and the battery can 20. For example, the first electrode tab 11 may be connected to the negative electrode of the electrode assembly 10, and the first current collector 50 may be named a negative current collector.

[0048] The secondary battery 1 may include a second current collector 60 that electrically connects the second electrode tab 11 and the terminal 40. For example, the second electrode tab 12 may be connected to the positive electrode of the electrode assembly 10, and the second current collector 60 may be named a positive current collector.

[0049] The first current collector 50 and the second current collector 60 may be located within the battery can 20 . The first current collecting plate 50 may be located between the electrode assembly 10 and the cap plate 30 in the height direction of the battery can 20. The first current collecting plate 50 may be coupled to the first electrode tab 11. More specifically, the first current collecting plate 50 may be welded to the first electrode tab 11. Also, the first current collecting plate 50 may be welded to the battery can 20, more specifically, to the beading portion 21.

[0050] The second current collecting plate 60 may be located between the electrode assembly 10 and one surface 20a of the battery can 20 in the height direction of the battery can 20. The second current collecting plate 60 may be coupled to the second electrode tab 12. More specifically, the second current collecting plate 60 may be welded to the second electrode tab 12. In addition, the second current collecting plate 60 may be welded to the terminal 40.

[0051] The secondary battery 1 may include a spacer 70 located between the cap plate 30 and the electrode assembly 10. More specifically, the spacer 70 may be located between the cap plate 30 and the first current collector plate 50.

[0052] The height of the spacer 70 can correspond to the distance between the cap plate 30 and the electrode assembly 10. The spacer 70 can prevent the electrode assembly 10 from moving or shaking within the battery can 20.

[0053] The secondary battery 1 may include an insulator 80 located between the electrode assembly 10 and the battery can 20. More specifically, the insulator 80 may be located between the second current collector plate 60 and the battery can 20.

[0054] The insulator 80 can insulate the second current collector 60 and the electrode assembly 10 from the battery can 20. The insulator 80 can be made of a resin material having insulating properties.

[0055] A hole through which the terminal 40 passes may be formed in the center of the insulator 80. The terminal 40 may be coupled to the second current collecting plate 60 through the hole.

[0056] The insulator 80 may have a substantially cap-shaped configuration. In this case, a portion of the insulator 80 may be located between the surface 20a of the battery can 20 and the second current collector plate 60, and another portion may be located between the outer periphery of the second current collector plate 60 and the inner periphery of the battery can 20.

[0057] However, without being limited thereto, the insulator 80 may have a plate shape located between one surface 20a of the battery can 20 and the second current collecting plate 60. In this case, an insulating tape separate from the insulator 80 may be interposed between the outer periphery of the second current collecting plate 60 and the inner periphery of the battery can 20.

[0058] The height of the insulator 80 can correspond to the vertical distance between one surface 20a of the battery can 20 and the electrode assembly 10. The insulator 80, together with the spacer 70, can prevent the electrode assembly 10 from moving or shaking within the battery can 20.

[0059] FIG. 3 is an enlarged cross-sectional view of the first current collecting plate and its periphery shown in FIG. 2, and FIG. 4 is a perspective view of the first current collecting plate according to an embodiment of the present invention. As described above, the first current collecting plate 50 may be coupled to the first electrode tab 11. More specifically, at least a portion of the first electrode tab 11 may be bent toward the hollow (C) of the electrode assembly 10, and the first current collecting plate 50 may be coupled to the bent portion of the first electrode tab 11. Although not shown in FIG 3, the bent portions of the adjacent first electrode tabs 11 may overlap each other.

[0060] This reduces the height of the first electrode tab 11, thereby improving the energy density of the secondary battery 1. In addition, since the bonding area between the first electrode tab 11 and the first current collector 50 increases, the bonding strength between the first electrode tab 11 and the first current collector 50 improves and the resistance can be reduced.

[0061] More specifically, the first current collector 50 may include a center portion 51, a tab connecting portion 52 extending outward from the center portion 51 and connecting to the first electrode tab 11, a can connecting portion 53 connecting to the battery can 20 and spaced apart from the tab connecting portion 52, and a bridge 54 connecting the can connecting portion 53 and the center portion 51.

[0062] The center portion 51 may be located at the center of one side (e.g., the lower side) of the electrode assembly 10. The center portion 51 may have a substantially circular shape. A center hole 51a may be formed in the center portion 51. The center hole 51a may face the hollow (C) of the electrode assembly 10. The center hole 51a, together with the hollow (C), may function as a passage for inserting a welding rod for bonding between the terminal 40 and the second current collecting plate 60 and for irradiating a laser. The center hole 51a may also function as a passage for smoothly impregnating the inside of the electrode assembly 10 with the electrolyte when the electrolyte is injected.

[0063] The tab coupling portion 52 may extend radially outward from the central portion 51. The tab coupling portion 52 may be coupled to the first electrode tab 11. A plurality of tab coupling portions 52 may be provided, and the plurality of tab coupling portions 52 may extend radially from the central portion 51.

[0064] The width of the tab coupling portion 52 may become wider as it is farther from the center portion 51. Thus, the tab coupling portion 52 may widely cover the bent portion of the first electrode tab 11, and thus the bent portion of the first electrode tab 11 may be prevented from floating.

[0065] The central axes of the electrode assembly 10, the battery can 20, and the first current collector plate 50 may be substantially aligned. In the radial direction of the battery can 20, the distance (R1) from the central axis of the electrode assembly 10 to the outer edge of the tab coupling portion 52 may be smaller than the radius (Ra) of the electrode assembly 10 and may be equal to or smaller than the inner radius (Rb) of the beading portion 21.

[0066] More specifically, the outer edge of the tab coupling portion 52 may be arc-shaped with a first radius of curvature (R1). The center of curvature of the outer edge may coincide with the center of the first current collector plate 50.

[0067] The first curvature radius (R1) may be smaller than a radius (Ra) of the electrode assembly 10. In addition, the first curvature radius (R1) may be equal to or smaller than an inner radius (Rb) of a beading portion 21 formed on a battery can 20.

[0068] The tab coupling portion 52 may not overlap the beading portion 21 in the height direction of the battery can 20. That is, the tab coupling portion 52 may not be located between the electrode assembly 10 and the beading portion 21. This can prevent the tab coupling portion 52 from being pinched between the electrode assembly 10 and the beading portion 21 and being damaged during a sizing process. Sizing may refer to a compression process in which the height of the beading portion 21 is reduced to reduce the height of the secondary battery 1 after the beading portion 21 and the crimping portion 22 are formed in the battery can 20 housing the electrode assembly 10.

[0069] A distance (R1) from the central axis of the electrode assembly 10 to an outer edge of the tab coupling portion 52 may be 2 / 3 or more of a radius (Ra) of the electrode assembly 10. More specifically, the first radius of curvature (R1) may be 2 / 3 or more of a radius (Ra) of the electrode assembly 10. This ensures a sufficiently wide contact area of ​​the tab coupling portion 52 with the electrode tab 11 of the electrode assembly 10.

[0070] Both side edges of the tab coupling portion 52 may be formed along the radial direction of the first current collector plate 50. An imaginary line extending along both side edges may pass through the center of the first current collector plate 50.

[0071] A liquid injection hole 52d may be formed in the tab coupling portion 52. The liquid injection hole 52d can improve the impregnation of the electrode assembly 10 with the electrolyte. The width of the liquid injection hole 52d may be wider as it is farther away from the center portion 51. This allows the electrolyte to be more uniformly impregnated into the electrode assembly 10, which has a longer winding length per unit angle as it moves radially outward.

[0072] The can coupling portion 53 may be coupled to the battery can 20, more specifically, to the beading portion 21. The can coupling portion 53 may be coupled to a surface of the beading portion 21 that is located relatively far from the electrode assembly 10.

[0073] The can coupling portion 53 may have a predetermined height difference with respect to the center portion 51 and the tab coupling portion 52. The height difference may refer to the distance between the tab coupling portion 52 and the can coupling portion 53 in the height direction of the battery can 20. The height difference may correspond to the height of the beading portion 21. That is, the distance between the tab coupling portion 52 and the can coupling portion 53 in the height direction of the battery can 20 may be the same as or similar to the height of the beading portion 21.

[0074] The can joint portion 53 may be pressed by a sealing portion 72, which will be described later. More specifically, the can joint portion 53 may be interposed between the sealing portion 72 and the beading portion 21 and fixed thereto.

[0075] The can coupling part 53 may be spaced apart from the tab coupling part 52. More specifically, the can coupling part 53 and the tab coupling part 52 may only be connected to the center part 51, respectively, and the can coupling part 53 and the tab coupling part 52 may not be directly connected to each other. As a result, when the secondary battery 1 is subjected to an impact or vibration, stress acting on the coupling part between the tab coupling part 52 and the first electrode tab 11 and the coupling part between the can coupling part 53 and the battery can 20 is dispersed, thereby minimizing the possibility of damage to the first current collector 50.

[0076] There may be a plurality of can coupling portions 53. The can coupling portions 53 and the tab coupling portions 52 may be arranged alternately in the circumferential direction of the first current collector plate 50. The can joint 53 may extend along the inner circumference of the battery can 20. That is, the can joint 53 may extend in the circumferential direction of the beading portion 21. This increases the contact area between the can joint 53 and the beading portion 21, so that the joint between the can joint 53 and the beading portion 21 is stable and the resistance between the can joint 53 and the beading portion 21 can be reduced.

[0077] A distance (R2) from the central axis of the electrode assembly 10 to the outer edge of the can joint 53 in the radial direction of the battery can 20 may be greater than a distance (R1) from the central axis of the electrode assembly 10 to the outer edge of the tab joint 52. Also, a distance (R3) from the central axis of the electrode assembly 10 to the inner edge of the can joint 53 in the radial direction of the battery can 20 may be smaller than a distance (R2) from the central axis of the electrode assembly 10 to the outer edge of the can joint 53.

[0078] More specifically, the outer edge of the can coupling portion 53 may be arc-shaped with a second radius of curvature (R2) greater than the first radius of curvature (R1) described above. Also, the inner edge of the can coupling portion 53 may be arc-shaped with a third radius of curvature (R2) smaller than the second radius of curvature (R2). The centers of curvature of the outer edge and the inner edge of the can coupling portion 53 may substantially coincide with the central axis of the electrode assembly 10.

[0079] The second radius of curvature (R2) may be greater than an inner radius (Rb) of a beading portion 21 formed on the battery can 20, and the third radius of curvature (R3) may be smaller than the inner radius (Rb) of the beading portion 21. That is, in the radial direction of the battery can 20, the distance (R2) from the central axis of the electrode assembly 10 to the outer edge of the can coupling portion 53 may be greater than the inner radius (Rb) of the beading portion 21, and the distance (R3) from the central axis of the electrode assembly 10 to the inner edge of the can coupling portion 53 may be smaller than the inner radius (Rb) of the beading portion 21.

[0080] If the second radius of curvature (R2) is equal to or smaller than the inner radius (Rb) of the beading portion 21, it is difficult for the can joint portion 53 to be joined to the beading portion 21. If the third radius of curvature (R3) is equal to or larger than the inner radius (Rb) of the beading portion 21, there is a concern that interference may occur between the bridge 54 (described later) and the beading portion 21.

[0081] Both side edges of the can joint 53 may be formed along the radial direction of the first current collector plate 50. An imaginary line extending along both side edges may pass through the center of the first current collector plate 50.

[0082] The can coupling portion 53 and the tab coupling portion 52 may not overlap each other in the height direction of the battery can 20. As a result, when a plurality of first current collecting plates 50 are stacked before being coupled to the electrode assembly 10, the can coupling portion 53 of one first current collecting plate 50 and the tab coupling portion 52 of the other first current collecting plate 50 can be prevented from interfering with each other.

[0083] The bonding strength between the can coupling portion 53 and the battery can 20, more specifically, between the can coupling portion 53 and the beading portion 21, may be greater than the bonding strength between the tab coupling portion 52 and the first electrode tab 11. This allows the can coupling portion 53 to be stably coupled to the battery can 20, which is a rigid body.

[0084] The bridge 54 may connect the can coupling portion 53 and the center portion 51. The bridge 54 may extend radially outward from the center portion 51 and may be spaced apart from the tab coupling portion 52 in the circumferential direction of the first current collector plate 50.

[0085] Similar to the can coupling portions 53, a plurality of bridges 54 may be provided, and the plurality of bridges 54 may extend in a radial direction from the center portion 51. The bridges 54 and the tab coupling portions 52 may be arranged alternately in the circumferential direction of the first current collector plate 50.

[0086] Since there is a height difference between the center portion 51 and the can coupling portion 53, the bridge 54 may be formed at an incline. The bridge 54 may extend at an incline in a direction away from the electrode assembly 10 as it moves away from the center portion 51.

[0087] The inclination of the bridge 54 may become gentler as it moves away from the center portion 51. More specifically, the bridge 54 may include a first inclined portion 54a extending from the center portion 51 and a second inclined portion 54b extending from the first inclined portion 54a and having a gentler inclination than the first inclined portion 54a. However, the present invention is not limited to this, and the bridge 54 may be formed in a rounded shape that becomes more gentle as it moves away from the center portion 51.

[0088] This prevents the bridge 54 from being excessively deformed during the sizing process, and prevents the center portion 51 and the first electrode tab 11 coupled thereto from floating. During the sizing process, the beading portion 21 is compressed toward the electrode assembly 10 and its height is reduced, so that the tab coupling portion 52 coupled to the beading portion 21 can also move toward the electrode assembly 10. As a result, a repulsive force in a direction away from the electrode assembly 10 acts on the center portion 51 connected to the tab coupling portion 52 via the bridge 54. If the inclination of the bridge 54 is constant or is formed to become steeper as it moves away from the center portion 51, the repulsive force acts strongly on the center portion 51, and therefore there is a concern that the center portion 51 and the first electrode tab 11 coupled thereto may float. In contrast, the bridge 54 according to the present embodiment can minimize the floating phenomenon of the center portion 51 and the first electrode tab 11 that occurs during the sizing process.

[0089] In addition, the process of radially inwardly pressing the outer periphery of the battery can 20 to form the beading portion 21 may be performed in a state in which the electrode assembly 10 to which the first current collecting plate 50 is coupled is housed in the battery can 20. In this process, since the bridge 54 has a gentler inclination as it moves away from the center portion 51, the beading portion 21 can be easily formed without interfering with the bridge 54.

[0090] Meanwhile, the edge of the cap plate 30 may be positioned between the beading portion 21 and the crimping portion 22 of the battery can 20 and may be fixed by a sealing portion 72 described below.

[0091] The cap plate 30 does not have to protrude from the battery can 20. For example, when the cap plate 30 is located at the lower end of the battery can 20, the bottom surface of the plate portion 31 of the cap plate 30 may be located on the same plane as the bottom surface of the battery can 20 or may be located higher than the bottom surface. This prevents the cap plate 30 from being pushed upward by the bottom surface supporting the battery can 20, and prevents a phenomenon in which the pressure required to break the vent portion 34 due to the weight of the secondary battery 1 differs from the design value.

[0092] The cap plate 30 may be formed with a vent portion 34. The vent portion 34 may be formed to have a thickness thinner than the surrounding area. As a result, the vent portion 34 may be structurally weaker than the surrounding area, and when the internal pressure of the battery can 20 increases beyond a preset value, the vent portion 34 may be preferentially broken.

[0093] The vent portion 34 may be formed along the circumferential direction of the cap plate 30. For example, the vent portion 34 may have a closed loop shape such as a loop. Therefore, when the vent portion 34 is broken, a region of the cap plate 30 located on the inside of the vent portion 34 can be easily separated to form an opening, and gas in the battery can 20 can be quickly discharged.

[0094] The vent portion 34 may be formed by notching both sides of the cap plate 30 to a predetermined depth to partially reduce the thickness of the cap plate 30. However, the present invention is not limited to this, and the vent portion 34 may be formed by notching only one side of the cap plate 30.

[0095] Meanwhile, the spacer 70 may be made of an elastic material in order to effectively absorb shock or vibration applied to the secondary battery 1 . The height of the spacer 70 may correspond to the distance between the first current collecting plate 50 and the cap plate 30. In this case, the body 71 may effectively prevent the electrode assembly 10 from moving within the battery can 20 due to a gap formed between the first current collecting plate 50 and the cap plate 30. Therefore, the spacer 70 may prevent damage to the bonding portion between the electrode assembly 10 and the first current collecting plate 50 and / or the bonding portion between the first current collecting plate 50 and the battery can 20.

[0096] The spacer 70 may have an opening facing the hollow (C) of the electrode assembly 10 through the center hole 51a of the first current collecting plate 50. The opening, together with the center hole 51a and the hollow (C), may function as a passage for inserting a welding rod or a passage for laser irradiation. The opening may also function as a passage for smoothly impregnating the inside of the electrode assembly 10 with an electrolyte.

[0097] The seal portion 72 may be formed integrally with the spacer 70. However, the present invention is not limited to this. The sealing portion 72 may be in the shape of a circular loop extending along the inner circumference of the battery can 20. The sealing portion 72 may be fixed between the beading portion 21 and the crimping portion 22 of the battery can 20. A part of the sealing portion 72 may be folded together with the crimping portion 22 to surround the edge of the cap plate 30. This allows the sealing portion 72 to tightly seal between the cap plate 30 and the battery can 20. In this way, the sealing portion 72 may function as a gasket for improving the fixing force of the cap plate 30 and the sealing force of the battery can 20.

[0098] The seal portion 72 can press the can coupling portion 53 of the first current collector plate 50 toward the beading portion 21, thereby further strengthening the coupling between the can coupling portion 53 and the beading portion 21. In addition, the seal portion 72 can insulate the can coupling portion 53 from the cap plate 30.

[0099] FIG. 5 is an enlarged cross-sectional view of the second current collecting plate and its surroundings shown in FIG. 2, FIG. 6 is a plan view of the second current collecting plate according to one embodiment of the present invention, and FIG. 7 is an enlarged view of the narrow portion shown in FIG. 6.

[0100] As described above, the terminal 40 may penetrate the center of one surface 20a of the battery can 20, be coupled to the second current collecting plate 60, and be electrically connected to the second electrode tab 12. In addition, the terminal 40 may be insulated from the battery can 20 by an insulating gasket (G).

[0101] More specifically, the terminal 40 may include a terminal portion 41 , a body portion 42 , and a protrusion portion 43 . The terminal portion 41 may be located outside the battery can 20. The terminal portion 41 may be a portion to which a bus bar (not shown) located outside the battery can 20 is connected. The terminal portion 41 may be in the form of a substantially circular flat plate.

[0102] The main body portion 42 may be formed integrally with the terminal portion 41. The main body portion 42 may penetrate the battery can 20 and be coupled to the second current collector plate 60, more specifically, to a tab coupling portion 64 described below. The main body portion 42 may be in the shape of a substantially circular column.

[0103] The protrusion 43 may protrude radially outward from the periphery of the body 42 and may be located inside the battery can 20. The protrusion 43 may be formed integrally with the body 42. The protrusion 43 may be formed to be inclined in a direction approaching the second current collecting plate 60 as it moves away from the outer periphery of the body 42.

[0104] The end of the protruding portion 43 does not have to protrude further toward the second current collecting plate 60 than the end of the main body portion 42. Therefore, damage to the second current collecting plate 60 by the protruding portion 43 can be prevented.

[0105] The diameter of the terminal portion 41 and the protruding portion 43 may be larger than the diameter of the main body portion 42. This allows the terminal 40 to be fixed to the battery can 20 so that it does not come off.

[0106] The insulating gasket (G) can insulate the terminal 40 from the battery can 20. More specifically, the insulating gasket (G) can be folded along the terminal portion 41 and the protruding portion 43 and fixed between the battery can 20 and the terminal 40.

[0107] Meanwhile, the insulator 80 can insulate the second current collector 60 from the battery can 20. The insulator 80 can be located between the second current collector 60 and the battery can 20. More specifically, the insulator 80 may include a plate portion 81 and a peripheral portion 82 .

[0108] The plate portion 81 may be located between the second current collector plate 60 and one surface 20a of the battery can 20. The plate portion 81 may have a substantially circular plate shape.

[0109] A hole through which the terminal 70 passes may be formed in the center of the plate portion 81. The terminal 40 may be coupled to the second current collecting plate 60 toward the hole. An end of the protrusion 43 of the terminal 40 may face the inner circumference of the hole.

[0110] The peripheral portion 82 may protrude from an edge of the plate portion 81 between the inner circumference of the battery can 20 and the outer circumference of the electrode assembly 10. The peripheral portion 82 may be formed integrally with the plate portion 81, but is not limited thereto.

[0111] The peripheral portion 82 can be located between the outer periphery of the second current collecting plate 60 and the second electrode tab 12 and the inner periphery of the battery can 20. The height of the peripheral portion 82 in the height direction of the battery can 20 may be greater than the sum of the heights of the second electrode tab 12 and the second current collecting plate 60. This enables the peripheral portion 82 to reliably insulate the second electrode tab 12 and the second current collecting plate 60 from the battery can 20. Meanwhile, the central axes of the electrode assembly 10, the battery can 20, and the second current collector plate 60 can be substantially aligned.

[0112] The second current collecting plate 60 may be coupled to the second electrode tab 12. More specifically, at least a portion of the second electrode tab 12 may be folded toward the hollow (C) of the electrode assembly 10, and the second current collecting plate 60 may be coupled to the folded portion 12a of the second electrode tab 12. Although not shown in FIG 5, the folded portions 12a of the multiple adjacent second electrode tabs 12 may overlap each other.

[0113] This reduces the height of the second electrode tab 12, thereby improving the energy density of the secondary battery 1. In addition, since the bonding area between the second electrode tab 12 and the second current collecting plate 60 increases, the bonding force between the second electrode tab 12 and the second current collecting plate 60 improves and the resistance can be reduced.

[0114] More specifically, the second current collecting plate 60 may include a rim portion 61, a terminal connecting portion 62 located inside the rim portion 61 and connecting to the terminal 40, a bridge 63 connecting the rim portion 61 and the terminal connecting portion 62, and a tab connecting portion 64 extending inward from the rim portion 61, spaced apart from the bridge 63 and the terminal connecting portion 62, and connecting to the second electrode tab 12.

[0115] The rim portion 61 may have a substantially circular rim shape, but is not limited thereto. The rim portion 61 may be located between the second electrode tab 12 and the insulator 80 in the height direction of the battery can 20.

[0116] The terminal coupling portion 62 may be located at the inner center of the rim portion 61. At least a portion of the terminal coupling portion 62 may face the hollow (C) of the electrode assembly 10.

[0117] The terminal coupling portion 62 may have a generally circular shape. The terminal coupling portion 62 may be coupled to the terminal 40, more specifically, to the body portion 42 of the terminal 40. For example, the terminal coupling portion 62 may be welded to a bottom surface of the body portion 42 of the terminal 40.

[0118] The bridge 63 may connect the rim portion 61 and the terminal coupling portion 62. The bridge 63 may extend radially inward from the rim portion 61. A plurality of bridges 63 may be provided, and the plurality of bridges 63 may extend in a radial direction from the terminal connection portion 62 .

[0119] The width of the outer end 63a of the bridge 63 may increase as it approaches the rim portion 61. This may improve the rigidity of the portion where the bridge 63 and the rim portion 61 are connected. In addition, when the second current collecting plate 60 is transferred or transported, the outer end 63a of the bridge 63, which has a relatively high rigidity, is gripped, and the second current collecting plate 60 may be transported stably.

[0120] The tab bond 64 can extend radially inward from the rim portion 61. The tab bond 64 can be bonded to the second electrode tab 12. For example, the tab bond 64 can be welded to the bent portion 12a of the second electrode tab 12.

[0121] The tab coupling portion 64 may be spaced apart from the terminal coupling portion 62. More specifically, the tab coupling portion 64 may be spaced apart from the terminal coupling portion 62 in the radial direction of the second current collecting plate 60. That is, the tab coupling portion 64 and the terminal coupling portion 62 may only be connected to the rim portion 61, respectively, and may not be directly connected to each other. As a result, when the secondary battery 1 is subjected to an impact or vibration, stress acting on the coupling portion between the tab coupling portion 64 and the second electrode tab 12 and the coupling portion between the terminal coupling portion 62 and the terminal 40 is dispersed, thereby minimizing the possibility of damage to the second current collecting plate 60.

[0122] The tab joint 64 may be spaced apart from the bridge 63. More specifically, the tab joint 64 may be spaced apart from the bridge 63 in the circumferential direction of the second current collector plate 60.

[0123] A plurality of tab coupling portions 64 may be provided. In the present embodiment, the number of tab coupling portions 64 may be the same as the number of bridges 63. The bridges 63 and the tab coupling portions 64 may be arranged alternately in the circumferential direction of the second current collecting plate 60. Each bridge 63 may be located between a pair of adjacent tab coupling portions 64 in the circumferential direction of the second current collecting plate 60.

[0124] The width (w2) of the bridge 63 may be equal to or smaller than the width (w4) of the tab connection portion 64. This increases the electrical resistance of the bridge 63, and when an overcurrent occurs, a part of the bridge 63 breaks, making it possible to cut off the overcurrent.

[0125] In order to improve the overcurrent blocking function, narrow portions 63b having a relatively narrow width may be formed in the bridge 63. For example, the narrow portions 63b may be recessed at both side edges of the bridge 63.

[0126] The width (w3) of the narrow portion 63b may be narrower than the width (w2) of the bridge 63. The width (w3) of the narrow portion 63b may be narrower than the width (w1) of the rim portion 61.

[0127] As a result, the electrical resistance in the narrow portion 63b increases, and when an overcurrent flows through the bridge 63, the narrow portion 63b breaks preferentially over the rim portion 61 and the bridge 63, thereby reliably cutting off the overcurrent. In other words, the narrow portion 63b can function as a fuse.

[0128] More specifically, the width (w3) of the narrow portion 63b may be 70% to 80% of the width (w2) of the bridge 63. This allows the reliability of the fuse function to be maintained high while maintaining the rigidity of the narrow portion 63b sufficiently high. If the width (w3) of the narrow portion 63b is smaller than 70% of the width (w2) of the bridge 63, there is a concern that the narrow portion 63b may be easily broken when the secondary battery 1 is subjected to impact or vibration. In addition, if the width (w3) of the narrow portion 63b is larger than 80% of the width (w2) of the bridge 63, there is a concern that the narrow portion 63b may not be broken preferentially when an overcurrent flows.

[0129] The narrow portion 63b may face the bent portion 12a of the second electrode tab 12 in the height direction of the electrode assembly 10. This allows the bent portion 12a of the second electrode tab 12 to prevent residues generated when the narrow portion 63b is broken from entering the electrode assembly 10. The narrowed portion 63b may be located closer to the outer end 63a of the bridge 63 at either end.

[0130] In the radial direction of the second current collecting plate 60, the distance (d) from the center of the second current collecting plate 60 to the narrow portion 63b may be 0.4 to 0.9 times the radius (Ra) of the electrode assembly 10. That is, in the radial direction of the electrode assembly 10, the distance (d) from the central axis of the electrode assembly 10 to the narrow portion 63b may be 0.4 to 0.9 times the radius (Ra) of the electrode assembly 10.

[0131] As described above, the folded portions 12a of the second electrode tabs 12 may overlap each other. In this case, the degree or number of overlaps of the folded portions 12a of the second electrode tabs 12 may be reduced in a portion of the region adjacent to the outer periphery of the electrode assembly 10 and a portion of the region adjacent to the hollow (C). For this reason, if the distance (d) from the center of the second current collecting plate 60 to the narrow portion 63b is less than 0.4 times or more than 0.9 times the radius (Ra) of the electrode assembly 10, there is a concern that residues generated when the narrow portion 63b breaks may enter the electrode assembly 10.

[0132] In contrast, in the present embodiment, when the distance (d) from the center of the second current collecting plate 60 to the narrow portion 63b is 0.4 to 0.9 times the radius (Ra) of the electrode assembly 10, the narrow portion 63b can face a region where the folded portions 12a of the second electrode tabs 12 sufficiently overlap each other in the height direction of the electrode assembly 10. This makes it possible to reliably prevent residues generated when the narrow portion 63b breaks from entering the electrode assembly 10.

[0133] At least one opening 65 may be formed between the rim portion 61 and the terminal coupling portion 62. When there are multiple bridges 63, multiple openings 65 may be formed, partitioned into multiple regions by the multiple bridges 63. The tab coupling portion 64 may reduce the area of ​​the opening 65.

[0134] More specifically, the area of ​​the at least one open portion 65 may be 40% to 99% of the total area of ​​the second current collecting plate 60. The total area of ​​the second current collecting plate 60 may refer to the total area of ​​the rim portion 61, the terminal coupling portion 62, the bridge 63, the tab coupling portion 64, and the open portion 65. This allows the open portion 65 to improve the impregnation of the electrode assembly 10 with the electrolyte. If the area of ​​the at least one open portion 65 is less than 40% of the total area of ​​the second current collecting plate 60, there is a concern that the impregnation of the electrode assembly 10 with the electrolyte may be reduced.

[0135] An inner end 64a of the tab coupling portion 64 may be spaced apart from the terminal coupling portion 62 to form a predetermined gap. The width of the inner end 64a of the tab coupling portion 64 may decrease as it approaches the terminal coupling portion 62. As a result, the area of ​​the open portion 65 may be further increased, and the impregnation of the electrolyte into the electrode assembly 10 may be improved.

[0136] The width (w1) of the rim portion 61 may be narrower than the width (w4) of the tab coupling portion 64. This ensures a sufficiently wide coupling area between the tab coupling portion 64 and the second electrode tab 12 while maintaining a sufficiently wide area of ​​the open portion 65.

[0137] The radius (R5) of the second current collecting plate 60 may be 33% to 102% of the radius (Ra) of the electrode assembly 10. In addition, the radius (R5) of the second current collecting plate 60 may be 33% to 98.5% of the inner radius (Rd) of the battery can 20. The radius (R5) of the second current collecting plate 60 may refer to the distance from the center of the second current collecting plate 60 to the outer periphery of the rim portion 61.

[0138] If the radius (R5) of the second current collector 60 is smaller than 33% of the radius (Ra) of the electrode assembly 10 or smaller than 33% of the inner radius (Rd) of the battery can 20, the function of the second current collector 60 as an electrical pathway connecting the second electrode tab 12 and the terminal 40 may be reduced.

[0139] Conversely, if the radius (R5) of the second current collector 60 is greater than 102% of the radius (Ra) of the electrode assembly 10 or greater than 98.5% of the inner radius (Rd) of the battery can 20, the rim portion 61 of the second current collector 60 may interfere with the peripheral portion 82 of the insulator 80. If the size of the battery can 20 is increased or the size of the electrode assembly 10 is reduced to prevent such interference, the energy density of the secondary battery 1 may decrease.

[0140] The radius (R4) of the terminal coupling portion 62 may be 40% to 320% of the radius (Rc) of the main body portion 42 that is coupled to the terminal coupling portion 62 of the terminal 40. More specifically, the radius (R4) of the terminal coupling portion 62 may be 40% to 320% of the radius (Rc) of the bottom surface of the main body portion 42.

[0141] If the radius (R4) of the terminal coupling portion 62 is smaller than 40% of the radius (Rc) of the main body portion 42, the coupling area between the terminal coupling portion 62 and the terminal 40 may become excessively small, and the resistance may increase. Conversely, if the radius (R4) of the terminal coupling portion 62 is larger than 320% of the radius (Rc) of the main body portion 42, the length of the tab coupling portion 64 separated from the terminal coupling portion 62 may become shorter, and the area of ​​the open portion 65 may decrease. For this reason, the coupling area between the second electrode tab 12 and the tab coupling portion 64 may decrease, and the resistance may increase, which may lead to a decrease in the impregnation of the electrode assembly 10 with the electrolyte.

[0142] Meanwhile, the difference between the bonding area between the first electrode tab 11 and the first current collecting plate 50 (see FIG. 3) and the bonding area between the second electrode tab 12 and the second current collecting plate 60 may be three times or less. For convenience of explanation, the bonding area between the first electrode tab 11 and the first current collecting plate 50 is named the first bonding area, and the bonding area between the second electrode tab 12 and the second current collecting plate 60 is named the second bonding area.

[0143] The first bonding area may be a bonding area between the first electrode tab 11 and a tab bonding portion 52 (see FIG. 4) of the first current collector plate 50. The second bonding area may be a bonding area between the second electrode tab 12 and a tab bonding portion 64 of the second current collector plate 60.

[0144] Either the first bonding area or the second bonding area may be three times or less than the other. Preferably, the first bonding area is the same as or similar to the second bonding area. This can prevent the resistance of either the first current collecting plate 50 or the second current collecting plate 60 from becoming excessively large.

[0145] The second current collector plate 60 does not need to overlap with the beading portion 21 (see FIG. 3) in the height direction of the electrode assembly 10. Alternatively, the second current collecting plate 60 may overlap the beading portion 21 in the height direction of the electrode assembly 10, and the width of the area of ​​the beading portion 21 that overlaps with the second current collecting plate 60 may be 80% or less of the width (wb) of the beading portion 21. That is, the second current collecting plate 60 may overlap 80% or less of the width (wb) of the beading portion 21 in the height direction of the electrode assembly 10. In this case, the width (wb) of the beading portion 21 may mean the width in the radial direction of the battery can 20.

[0146] If the second current collecting plate 60 overlaps the electrode assembly 10 in the height direction by more than 80% of the width (wb) of the beading portion 21, the second current collecting plate 60 may interfere with the peripheral portion 82 of the insulator 80. If the size of the battery can 20 is increased or the size of the electrode assembly 10 is reduced to prevent this interference, the energy density of the secondary battery 1 may decrease.

[0147] FIG. 8 is a diagram showing a modification of the narrow portion shown in FIG. As described above, the narrow portion 63b may be recessed at both edges of the bridge 63. However, without being limited thereto, the narrow portion 63b may be formed by penetrating the bridge 63 as shown in FIG.

[0148] More specifically, a hole may be formed in the center of the bridge 63 in the width direction, and both sides of the hole may form the narrow portion 63b. In this case, the width (w3) of the narrow portion 63b may mean the combined value of the width (w31) of one side of the hole and the width (w32) of the other side. The above content is used to refer to the width (w3) of the narrow portion 63b.

[0149] FIG. 9 is a diagram showing how the narrow portion shown in FIG. 6 is surrounded by a cover member. A cover member 63c made of an insulating material surrounding the narrow portion 63b may be provided on the bridge 63 of the second current collector plate 60. For example, the cover member 63c may be a tape wound in a tape shape to surround the narrow portion 63b.

[0150] The cover member 63c can prevent residues generated when the bridge 63, particularly the narrow portion 63b, breaks due to an overcurrent from being dispersed to the surroundings. In addition, since the cover member 63c can reduce the heat dissipation of the narrow portion 63b, the amount of heat generated in the narrow portion 63b can be further increased and the narrow portion 63b can be broken more quickly when an overcurrent flows through the bridge 63. In order to effectively reduce the heat dissipation of the narrow portion 63b, the thermal conductivity of the cover member 63c may be lower than that of the bridge 63.

[0151] For example, the cover member 63c may include a polyimide (PI) material, which has a melting point of approximately 375° C. to 401° C. and therefore does not melt due to heat generated by the bridge 63.

[0152] 9, the bridge 63 may not have the narrow portion 63b, and the cover member 63c may surround a specific point of the bridge 63. In this case, the cover member 63c can reduce heat dissipation at the specific point of the bridge 63, so that when an overcurrent flows through the bridge 63, the amount of heat generated at the specific point increases, and the bridge 63 can break preferentially. That is, the specific point of the bridge 63 surrounded by the cover member 63c can function as a fuse.

[0153] Therefore, some of the description regarding the narrow portion 63b can be applied to the cover member 63c. More specifically, the cover member 63c can be located closer to the outer end 63a of both ends of the bridge 63. Also, the cover member 63c can face the bent portion 12a of the second electrode tab 12 in the axial direction of the electrode assembly 10. Also, in the radial direction of the second current collecting plate 60, the distance from the center of the second current collecting plate 60 to the cover member 63c can be 0.4 to 0.9 times the radius (Ra) of the electrode assembly 10.

[0154] FIG. 10 is a plan view of a second current collector plate according to another embodiment of the present invention. In the following, the contents that overlap with those described above will be cited, and the differences will be mainly described. In the second current collector plate 60 according to this embodiment, the number of bridges 63 may be less than the number of tab coupling portions 64 .

[0155] More specifically, some of the multiple tab coupling portions 64 may be arranged continuously in the circumferential direction of the second current collecting plate 60. That is, the tab coupling portions 64 and the bridges 63 do not have to be arranged alternately in the circumferential direction of the second current collecting plate 60. The bridges 63 may be located between a pair of adjacent tab coupling portions 64 in the circumferential direction of the second current collecting plate 60.

[0156] This increases the amount of current flowing through each bridge 63, thereby increasing the sensitivity of the narrow portions 63b to overcurrent. Therefore, the narrow portions 63b can be broken more quickly, and the safety of the secondary battery 1 can be improved.

[0157] The above description is merely an illustrative example of the technical concept of the present invention, and various modifications and variations can be made by those having ordinary knowledge in the technical field to which the present invention pertains without departing from the essential characteristics of the present invention.

[0158] Therefore, the embodiments disclosed in the present invention are intended to explain and not to limit the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by such embodiments.

[0159] The scope of protection of the present invention should be interpreted according to the claims set forth below, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0160] 1: Cylindrical secondary battery 10: Electrode assembly 11: First electrode tab 12: Second electrode tab 20: Battery can 21: Beading section 22: Crimping section 30: Cap plate 34: Vent section 40: Terminal 41:Terminal section 42: Main body 43:Protrusion 50: First current collector 51: Center section 51a: Center hole 52: Tab joint 52d: Liquid injection hole 53: Can joint 54: Bridge 60: Second current collector 61: Rim section 62:Terminal connection part 63: Bridge 63a: Outer end (of bridge) 63b: Narrow part 63c: Cover material 64: Tab joint 64a: Inner end (of tab joint) 65:Open part 70: Spacer 72: Seal part 80: Insulator 81: Plate section 82: Periphery

Claims

1. an electrode assembly having an electrode tab; a battery can that houses the electrode assembly; a terminal penetrating the battery can and insulated from the battery can; a current collecting plate electrically connecting the electrode tab and the terminal; Including, The current collector plate is A rim portion and a terminal coupling portion located inside the rim portion and coupled to the terminal; a bridge connecting the rim portion and the terminal coupling portion; a tab coupling portion extending inwardly from the rim portion, spaced apart from the bridge and the terminal coupling portion, and coupling to the electrode tab; Including, The inner end of the tab coupling portion has a width that decreases toward the terminal coupling portion.

2. The cylindrical secondary battery according to claim 1 , wherein the bridges and the tab connecting portions are alternately arranged in a circumferential direction of the current collector plate.

3. The cylindrical secondary battery according to claim 1 , wherein the outer end of the bridge has a width that increases toward the rim portion.

4. The cylindrical secondary battery according to claim 1 , wherein the bridge has a narrow portion having a relatively narrow width.

5. 5. The cylindrical secondary battery according to claim 4, wherein the width of the narrow portion is 70% to 80% of the width of the bridge.

6. 5. The cylindrical secondary battery according to claim 4, wherein the narrowed portion is located closer to the outer end of each of the two ends of the bridge.

7. 5. The cylindrical secondary battery according to claim 4, wherein a distance from a center of the current collector plate to the narrow portion in a radial direction of the current collector plate is 0.4 to 0.9 times a radius of the electrode assembly.

8. At least a portion of the electrode tab is bent toward a central axis of the electrode assembly; The cylindrical secondary battery according to claim 4 , wherein the narrow portion faces the bent portion of the electrode tab in the axial direction of the electrode assembly.

9. The cylindrical secondary battery according to claim 4 , wherein the narrow portion is formed by recessing both side edges of the bridge or penetrating the bridge.

10. The cylindrical secondary battery according to claim 4 , wherein the narrow portion has a width smaller than a width of the rim portion.

11. The cylindrical secondary battery according to claim 1 , wherein the bridge is provided with a cover member that surrounds the bridge and is made of an insulating material having a lower thermal conductivity than the bridge.

12. The cylindrical secondary battery of claim 11 , wherein the cover member includes a polyimide (PI) material.

13. The cylindrical secondary battery according to claim 1 , wherein the width of the rim portion is narrower than the width of the tab connection portion.

14. The cylindrical secondary battery according to claim 1 , wherein the radius of the current collector plate is 33% to 102% of the radius of the electrode assembly.

15. 2. The cylindrical secondary battery according to claim 1, wherein the radius of the current collector plate is 33% to 98.5% of the inner radius of the battery can.

16. 2. The cylindrical secondary battery according to claim 1, wherein a radius of the terminal coupling portion is 40% to 320% of a radius of a main body portion of the terminal that is coupled to the terminal coupling portion.

17. At least one opening is formed between the rim portion and the terminal coupling portion, 2. The cylindrical secondary battery according to claim 1, wherein the ratio of the area of ​​the at least one open portion to the total area of ​​the current collector plate is 40% to 99%.

18. A current collector that electrically connects an electrode assembly to a terminal that penetrates a battery can in which the electrode assembly is housed, A rim portion and a terminal coupling portion located inside the rim portion and coupled to the terminal; a bridge connecting the rim portion and the terminal coupling portion; a tab coupling portion extending inward from the rim portion, spaced apart from the bridge and the terminal coupling portion, and coupled to an electrode tab provided on the electrode assembly; Including, The inner end of the tab coupling portion has a width that decreases toward the terminal coupling portion.

19. an electrode assembly including a first electrode tab and a second electrode tab; a battery can that houses the electrode assembly; a terminal penetrating the battery can and insulated from the battery can; a first current collecting plate electrically connecting the first electrode tab and the battery can; a second current collecting plate electrically connecting the second electrode tab and the terminal; Including, a difference between a bonding area between the first electrode tab and the first current collector plate and a bonding area between the second electrode tab and the second current collector plate is three times or less.

20. a press-fit beading portion is formed between a cap plate and the electrode assembly at a periphery of the battery can; The cylindrical secondary battery according to claim 19 , wherein the can-joining portion of the first current collector plate is joined to the beading portion.

21. The cylindrical secondary battery of claim 20 , wherein the second current collector plate does not overlap the beading portion in a height direction of the electrode assembly.

22. the second current collecting plate overlaps with the beading portion in a height direction of the electrode assembly, The cylindrical secondary battery according to claim 20 , wherein a width of the area of ​​the beading portion that overlaps with the second current collector plate is 80% or less of a width of the beading portion.

Images