Cylindrical secondary battery

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 accommodates the electrode assembly through an opening formed on one side, a cap plate that covers the opening, a current collector disposed between the electrode assembly and the cap plate and electrically connecting the electrode tab and the battery can, and a spacer having a body portion located between the current collector and the cap plate, a sealing portion that seals between the battery can and the cap plate, and a connecting portion that connects the body portion and the sealing portion. The current collector may include a center portion, a tab connecting portion that extends outward from the center portion and is connected to the electrode tab, a can connecting portion that is connected to the battery can and has a height difference with the tab connecting portion, and a bridge that connects the center portion and the can connecting portion and extends in a direction away from the electrode assembly as it moves away from the center portion. The bridge of the current collector and the connecting portion of the spacer may be arranged to be offset from each other so as not to overlap with each other in a height direction of the battery can.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0010937, filed on January 25, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference. The present invention relates to a cylindrical secondary battery. [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 cylindrical secondary battery including a current collector having a structure suitable for an electrode assembly having a low resistance structure.

[0007] Another object of the present invention is to provide a cylindrical secondary battery including 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. [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 that accommodates the electrode assembly through an opening formed on one side, a cap plate that covers the opening, a current collector disposed between the electrode assembly and the cap plate and electrically connecting the electrode tab and the battery can, and a spacer having a body portion located between the current collector and the cap plate, a sealing portion that seals between the battery can and the cap plate, and a connecting portion that connects the body portion and the sealing portion. The current collector may include a center portion, a tab connecting portion that extends outward from the center portion and is connected to the electrode tab, a can connecting portion that is connected to the battery can and has a height difference with the tab connecting portion, and a bridge that connects the center portion and the can connecting portion and extends in a direction away from the electrode assembly as it moves away from the center portion. The bridge of the current collector and the connecting portion of the spacer may be arranged to be offset from each other so as not to overlap with each other in a height direction of the battery can.

[0009] The bridge and tab connection portions may be arranged alternately in the circumferential direction of the center portion. The tab joint portion and the can joint portion do not need to overlap in the height direction of the battery can.

[0010] The bridge may have a gentler inclination as it moves away from the center portion. The can joint may extend along an inner periphery of the battery can. The tab connection portion may have a width that increases with distance from the center portion.

[0011] At least one liquid inlet may be formed in the tab connection portion. The injection hole may be formed so that its width increases as it moves away from the center portion.

[0012] In a radial direction of the battery can, a distance from a central axis of the battery can to an outer edge of the can joint may be greater than a distance from the central axis of the battery can to an outer edge of the tab joint.

[0013] The outer edge of the tab attachment portion may be arcuate having a first radius of curvature and the outer edge of the can attachment portion may be arcuate having a second radius of curvature greater than the first radius of curvature.

[0014] A press-fit beading portion may be formed between the cap plate and the electrode assembly at a periphery of the battery can, and the can coupling portion may be coupled to the beading portion.

[0015] The cylindrical secondary battery may further include a sealing portion surrounding an edge of the cap plate, and the can coupling portion may be interposed and fixed between the sealing portion and the beading portion.

[0016] The can coupling portion may include an outer region overlapping the beading portion in a height direction of the battery can, and an inner region located inside the outer region and coupled to the bridge.

[0017] The tab connection portion may not overlap the beading portion in the height direction of the can. The distance from the central axis of the battery can to the outer edge of the tab connection portion may be greater than or equal to 2 / 3 of the radius of the electrode assembly.

[0018] A height difference between the tab joint portion and the can joint portion may correspond to a height of the beading portion. A bond strength between the battery can and the can bond may be greater than a bond strength between the electrode tab and the tab bond.

[0019] A press-fit beading portion may be formed between the cap plate and the electrode assembly at a periphery of the battery can, and the can coupling portion may be welded onto a flat region of the beading portion.

[0020] The weld bead formed at the can joint may be located inside the boundary of the flat region at a distance of 0.1 mm or more. The cap plate may have a vent portion having a thickness that is 1 / 10 or less of the thickness of the cap plate.

[0021] The height of the body portion may correspond to the distance between the current collector plate and the cap plate. The main body portion does not need to apply pressure to the current collecting plate.

[0022] The sealing portion may surround an edge portion of the cap plate to insulate the battery can from the cap plate. A distance between the connecting portion and the cap plate may increase as the connecting portion is farther away from the body portion. Effect of the Invention

[0023] 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.

[0024] In addition, even if vibrations and impacts are applied during use of the secondary battery, the possibility of damage occurring to 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]

[0025] 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.

[0026] [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] FIG. 2 is a plan view of a first current collecting plate according to one embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view taken along line AA' in FIG. 5. [Figure 7] 4 is an enlarged cross-sectional view showing a state in which a first current collecting plate is coupled to a beading portion according to an embodiment of the present invention. FIG. [Figure 8] 4 is a plan view showing a state in which a first current collecting plate is coupled to a beading portion according to an embodiment of the present invention. FIG. [Figure 9] FIG. 13 is a perspective view of a cap plate and a spacer according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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 .

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] FIG. 3 is an enlarged cross-sectional view of the first current collecting plate and its surroundings shown in FIG. 2, FIG. 4 is an oblique view of the first current collecting plate according to one embodiment of the present invention, FIG. 5 is a plan view of the first current collecting plate according to one embodiment of the present invention, and FIG. 6 is a cross-sectional view taken along line A-A' in FIG. 5.

[0063] Hereinafter, the first current collector plate 50 will be described with reference to FIGS. 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.

[0064] 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.

[0065] 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.

[0066] The center portion 51 may be located at the center of one side (e.g., the lower side) of the electrode assembly 10. 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 or for irradiating a laser. In addition, the center hole 51a may function as a passage for smoothly impregnating the inside of the electrode assembly 10 with the electrolyte when the electrolyte is injected.

[0067] 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.

[0068] 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.

[0069] 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 battery can 20 to the outer edge 52a 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.

[0070] More specifically, the outer edge 52a of the tab coupling portion 52 may be an arc shape having a first radius of curvature (R1). The center of curvature of the outer edge 52a may coincide with the center of the first current collector plate 50.

[0071] 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.

[0072] 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.

[0073] A distance (R1) from the central axis of the battery can 20 to an outer edge 52a 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.

[0074] Both side edges 52b 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 52b may pass through the center of the first current collector plate 50.

[0075] 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 liquid inlet 52d may be located outside the coupling region 52c of the tab coupling portion 52 which couples with the first electrode tab 11. For example, a pair of liquid inlet holes 52d may be formed in the tab coupling portion 52, and the pair of liquid inlet holes 52d may be formed with the coupling region 52c therebetween. In this case, the width (W) of the coupling region 52c may be formed to be constant. The pair of liquid inlet holes 52d may have symmetrical shapes with respect to the coupling region 52c.

[0076] 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.

[0077] 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.

[0078] The can coupling portion 53 may have a predetermined height difference (H) with respect to the center portion 51 and the tab coupling portion 52. The height difference (H) 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 (H) 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.

[0079] 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.

[0080] 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 area 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.

[0081] 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.

[0082] In the radial direction of the battery can 20, the distance (R2) from the central axis of the battery can 20 to the outer edge 53a of the can joint 53 may be greater than the distance (R1) from the central axis of the battery can 20 to the outer edge 52a of the tab joint 52. In addition, in the radial direction of the battery can 20, the distance (R3) from the central axis of the battery can 20 to the inner edge 53b of the can joint 53 may be smaller than the distance (R2) from the central axis of the battery can 20 to the outer edge 53a of the can joint 53.

[0083] More specifically, the outer edge 53a of the can coupling portion 53 may be arc-shaped with a second radius of curvature (R2) larger than the first radius of curvature (R1) described above. Also, the inner edge 53a 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 53a and the inner edge 53b of the can coupling portion 53 may substantially coincide with the central axis of the battery can 20.

[0084] 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 battery can 20 to an outer edge 53a of the can joint 53 may be greater than the inner radius (Rb) of the beading portion 21, and the distance (R3) from the central axis of the battery can 20 to an inner edge 53b of the can joint 53 may be smaller than the inner radius (Rb) of the beading portion 21.

[0085] 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.

[0086] Both side edges 53c of the can coupling portion 53 may be formed along the radial direction of the first current collecting plate 50. An imaginary line extending along both side edges 53c may pass through the center of the first current collecting plate 50.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] Since there is a height difference (H) 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.

[0092] 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.

[0093] The first inclined portion 54a can form a first angle (a1) with respect to a horizontal plane perpendicular to the height direction of the battery can 20, and the second inclined portion 54b can form a second angle (a2) smaller than the first angle (a1). 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.

[0094] 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 53 coupled to the beading portion 21 can also move toward the electrode assembly 10. As a result, a repulsive force acts on the center portion 51 connected to the tab coupling portion 53 via the bridge 54 in a direction away from the electrode assembly 10. 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 on the center portion 51 to a large extent, 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 of the center portion 51 and the first electrode tab 11 that occurs during the sizing process.

[0095] 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.

[0096] FIG. 7 is an enlarged cross-sectional view showing a state in which a first current collecting plate according to one embodiment of the present invention is coupled to a beading portion, and FIG. 8 is a plan view showing a state in which a first current collecting plate according to one embodiment of the present invention is coupled to a beading portion.

[0097] The connection between the can connection portion 53 of the first current collector plate 50 and the beading portion 21 may be performed before the crimping portion 22 (see FIG. 3) is formed on the battery can 20 .

[0098] The can coupling portion 53 may include an outer region 531 that overlaps with the beading portion 21 in the height direction of the battery can 20, and an inner region 532 that is located more inward than the outer region 531. That is, a part of the inner side of the can coupling portion 53 may not overlap with the beading portion 21 in the height direction of the battery can 20. Since the inner region 532 is connected to the bridge 54 described above, it is possible to minimize the concern that the beading portion 21 will interfere with the bridge 54.

[0099] Meanwhile, the can joint portion 53 may be welded to the flat region 21a on the beading portion 21. That is, the weld bead 53d formed on the can joint portion 53 may be located on the flat region 21a.

[0100] The weld bead 53d may be formed long in the circumferential direction of the beading portion 21. Each can joint portion 53 may have at least one weld bead 53d formed therein.

[0101] When the beading portion 21 is formed, a portion connecting the periphery of the battery can 20 and the beading portion 21 may be formed in a rounded shape. Therefore, the flat region 21a may be spaced apart from the inner circumference of the battery can 20 in the radially inward direction of the battery can 20.

[0102] The welding position of the can joint 53 to the flat region 21a may be spaced apart from the boundary of the flat region 21a. That is, the weld bead 53d formed at the can joint 53 may be formed on the inside with a predetermined interval from the boundary of the flat region 21a. Preferably, the weld bead 53d may be formed on the inside with an interval of 0.1 mm or more from the boundary of the flat region 21a. For example, based on the outer periphery of the battery can 20, the distance (d1) to the outer boundary of the flat region 21a may be 1.95 mm, and the distance (d2) to the inner boundary of the flat region 21a may be 3.15 mm. In this case, based on the outer periphery of the battery can 20, the position of the weld bead 53d may be located in an area of ​​2.05 mm to 3.05 mm.

[0103] This can eliminate the concern that weld bead 53d of can joint 53 will extend beyond the boundary of flat region 21a, and can joint 53 can be stably welded to flat region 21a.

[0104] FIG. 9 is a perspective view of a cap plate and a spacer according to another embodiment of the present invention. The cap plate 30 and the spacer 70 will now be described with reference to FIGS.

[0105] The cap plate 30 may include a plate portion 31, an inclined portion 32 extending from a periphery of the plate portion 31 and formed in an inclined shape, and an edge portion 33 extending from the inclined portion 32. The plate portion 31, the inclined portion 32, and the edge portion 33 may be integrally formed.

[0106] The plate portion 31 may have a substantially flat disk shape. The inclined portion 32 may be formed to be inclined in a direction approaching the electrode assembly 10 as it is farther from the plate portion 31.

[0107] The edge portion 33 may be substantially parallel to the plate portion 31 and may have a predetermined height difference with respect to the plate portion 31. More specifically, the distance from the electrode assembly 10 to the plate portion 31 in the height direction of the battery can 20 may be greater than the distance from the electrode assembly 10 to the edge portion 31.

[0108] The edge portion 33 may be located between the beading portion 21 and the crimping portion 22 of the battery can 20. The edge portion 33 may be fixed by a sealing portion 72, which will be described later. This allows the rigidity of the cap plate 30 to be increased, as compared to a case in which the entire cap plate 30 is formed flat.

[0109] The cap plate 30 may have a vent portion 34 formed therein. More specifically, the vent portion 31 may be formed in the plate portion 31 of the cap plate 30.

[0110] The vent portion 34 may be formed to have a thickness thinner than that of the plate portion 31. 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.

[0111] 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.

[0112] If the internal pressure of the battery can 20 is the same, the force applied to the vent portion 34 can be greater as the area located inside the vent portion 34 in the cap plate 30 becomes larger. Therefore, in order to quickly break the vent portion 34, the vent portion 34 can be formed closer to the inclined portion 32 than to the center of the plate portion 31. Preferably, the vent portion 31 can be formed adjacent to the inclined portion 32.

[0113] The thickness (t2) of the vent portion 34 may be 1 / 10 or less of the thickness (t1) of the cap plate 30, more specifically, the plate portion 31. If the thickness (t2) of the vent portion 34 is greater than 1 / 10 of the thickness (t1) of the plate portion 31, the vent portion 34 may not break easily.

[0114] 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. If only one side of the cap plate 30 is notched, there is a concern that the shape of the cap plate 30 may be deformed.

[0115] The center of the cap plate 30 can coincide with the central axis of the battery can 20. When the vent portion 31 is formed along the circumferential direction of the cap plate 30, the distance from the center of the cap plate 30 to the vent portion 31 may be the radius of curvature (Rc) of the closed curve formed by the vent portion 31.

[0116] A portion of the vent portion 34 may overlap the tab coupling portion 52 of the first current collector plate 50 in the height direction of the battery can 20. More specifically, a distance (R1) from the central axis of the battery can 20 to an outer edge 52a of the tab coupling portion 52 of the first current collector plate 50 may be greater than a distance (Rc) to the vent portion 34 of the cap plate 30. That is, the first radius of curvature (R1) may be greater than the radius of curvature (Rc) of the vent portion 31. This may be a feature for the tab coupling portion 52 to have a sufficiently wide contact area with the first electrode tab 11.

[0117] 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.

[0118] Meanwhile, the spacer 70 can prevent the electrode assembly 10 from shaking or moving and can strengthen the sealing force of the battery can 20. The spacer 70 can have an elastic material to effectively absorb impacts or shaking applied to the secondary battery 1.

[0119] More specifically, the spacer 70 may include a body portion 71 located between the first current collecting plate 50 and the cap plate 30, a seal portion 72 that seals between the battery can 20 and the cap plate 30, and a connecting portion 73 that connects the body portion 71 and the seal portion 72. The body portion 71, the seal portion 72, and the connecting portion 73 may be integrally formed.

[0120] The main body portion 71 may be located at approximately the center of the electrode assembly 10 with the first current collecting plate 50 therebetween. The main body portion 71 may face the first current collecting plate 50, more specifically, the center portion 51.

[0121] The main body 71 may have a spacer hole 71a formed therein, facing the hollow (C) of the electrode assembly 10 through the center hole 51a of the first current collecting plate 50. The spacer hole 71a, 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 spacer hole 71a may also function as a passage for allowing the inside of the electrode assembly 10 to be smoothly impregnated with an electrolyte.

[0122] The height of the body portion 71 may correspond to the distance between the first current collecting plate 50 and the cap plate 30. In this case, the body portion 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 body portion 71 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.

[0123] Before the sizing process is performed, the distance between the first current collecting plate 50 and the cap plate 30 may be greater than the height of the body part 71, and the height of the beading part 21 is reduced by the sizing process, so that the distance between the first current collecting plate 50 and the cap plate 30 may be the same as or similar to the height of the body part 71. Therefore, the body part 71 does not elastically deform between the cap plate 30 and the first current collecting plate 50, and the body part 71 does not press the first current collecting plate 50. This can prevent the first current collecting plate 50 from being damaged by the spacer 70.

[0124] 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 fix the cap plate 30, more specifically, the edge portion 33. 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.

[0125] 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.

[0126] The connecting portion 73 may connect the main body portion 71 and the sealing portion 72. A plurality of connecting portions 73 may be provided, and the plurality of connecting portions 73 may extend radially from the main body portion 71 to the sealing portion 72. An electrolyte may be smoothly injected through spaces between the plurality of connecting portions 73. In addition, when the vent portion 34 is broken due to an increase in the internal pressure of the battery can 20, gas inside the battery can 20 may be smoothly discharged through the spaces between the plurality of connecting portions 73.

[0127] The distance between the connecting portion 73 and the cap plate 30 may increase as it moves away from the body portion 71. More specifically, in the height direction of the battery can 20, the distance between the connecting portion 73 and the plate portion 31 of the cap plate 30 may increase as it moves toward the radially outer side of the battery can 20.

[0128] As a result, deformation of the connecting portion 73 of the spacer 70 caused by a compressive force in the height direction being applied to the battery can 20 during the sizing process can be minimized, and even if deformation does occur, interference with the cap plate 30 can be minimized.

[0129] The connecting portion 73 does not have to overlap with the bridge 54 of the first current collector plate 50 in the height direction of the battery can 20. The connecting portion 73 can overlap with the tab coupling portion 52 of the first current collector plate 50 in the height direction of the battery can 20.

[0130] More specifically, the bridges 54 of the first current collector 50 and the connecting portions 73 of the spacer 70 may be arranged to be offset from one another so as not to overlap with one another in the height direction of the battery can 20. That is, the bridges 54 and the connecting portions 73 may be positioned alternately with one another in the circumferential direction.

[0131] As a result, when a compressive force in the height direction is applied to the battery can 20 during the sizing process, and deformation occurs in the connecting portion 73 of the spacer 70 and the bridge 54 of the first current collector 50, interference between the connecting portion 73 and the bridge 54 can be prevented.

[0132] 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.

[0133] 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.

[0134] 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]

[0135] 1: Cylindrical secondary battery 10: Electrode assembly 11: First electrode tab 12: Second electrode tab 20: Battery can 21: Beading section 21a: Flat area 22: Crimping section 30: Cap plate 31: Plate section 32: Inclined part 33: Edge section 34: Vent section 40: Terminal 50: First current collector 51: Center section 51a: Center hole 52: Tab joint 52a: Outer edge (of tab joint) 52b: Both edges (of the tab joint) 52c: Combined area 52d: Liquid injection hole 53: Can joint 531: Outer Region 532: Inner Region 53a: Outer edge of (can joint) 53b: Inner edge of (can joint) 53c: Both edges of (can joint) 53d: Weld bead 54: Bridge 54a: 1st slope part 54b: Second slope part 60: Second current collector 70: Spacer 71: Main body 72: Seal part 73:Connection part 80: Insulator

Claims

1. an electrode assembly having an electrode tab; a battery can that accommodates the electrode assembly through an opening formed on one side thereof; A cap plate for covering the opening; a current collecting plate disposed between the electrode assembly and the cap plate to electrically connect the electrode tab and the battery can; a spacer including a body portion located between the current collecting plate and the cap plate, a seal portion that seals between the battery can and the cap plate, and a connecting portion that connects the body portion and the seal portion; Including, The current collector plate is The center section and a tab coupling portion extending outward from the center portion and coupled to the electrode tab; a can coupling portion coupled to the battery can and having a height difference with the tab coupling portion; a bridge connecting the center portion and the can coupling portion, the bridge extending at an angle from the center portion to the electrode assembly, a cylindrical secondary battery, wherein the bridge of the current collector plate and the connecting portion of the spacer are offset from each other in a height direction of the battery can so as not to overlap each other.

2. The cylindrical secondary battery according to claim 1 , wherein the bridges and the tab connection portions are alternately arranged in a circumferential direction of the center portion.

3. The cylindrical secondary battery according to claim 1 , wherein the tab joint portion and the can joint portion do not overlap in a height direction of the battery can.

4. The cylindrical secondary battery according to claim 1 , wherein the bridge has a gradually increasing inclination as it moves away from the center portion.

5. The cylindrical secondary battery according to claim 1 , wherein the can joint portion extends along an inner circumference of the battery can.

6. The cylindrical secondary battery according to claim 1 , wherein the tab connection portion has a width that increases with increasing distance from the center portion.

7. The cylindrical secondary battery according to claim 1 , wherein the tab connection portion is formed with at least one liquid injection hole.

8. The cylindrical secondary battery according to claim 7 , wherein the liquid injection hole is formed so that its width increases with increasing distance from the center portion.

9. 2. The cylindrical secondary battery according to claim 1, wherein a distance from a central axis of the battery can to an outer edge of the can joint in a radial direction of the battery can is greater than a distance from the central axis of the battery can to an outer edge of the tab joint.

10. an outer edge of the tab connection portion is arcuate having a first radius of curvature; The cylindrical secondary battery according to claim 1 , wherein an outer edge of the can joint is arc-shaped having a second radius of curvature larger than the first radius of curvature.

11. a press-fit beading portion is formed between the cap plate and the electrode assembly at a periphery of the battery can; The cylindrical secondary battery according to claim 1 , wherein the can-joining portion is joined to the beading portion.

12. The cap plate further includes a seal portion surrounding a periphery of the cap plate; The cylindrical secondary battery according to claim 11 , wherein the can coupling portion is interposed and fixed between the sealing portion and the beading portion.

13. The can joint is an outer region overlapping the beading portion in a height direction of the battery can; The cylindrical secondary battery according to claim 11 , further comprising: an inner region located inside the outer region and connected to the bridge.

14. The cylindrical secondary battery according to claim 11 , wherein the tab connection portion does not overlap the beading portion in a height direction of the battery can.

15. The cylindrical secondary battery according to claim 11 , wherein a distance from a central axis of the battery can to an outer edge of the tab connection portion is equal to or greater than ⅔ of a radius of the electrode assembly.

16. The cylindrical secondary battery of claim 11 , wherein a height difference between the tab joint portion and the can joint portion corresponds to a height of the beading portion.

17. The cylindrical secondary battery according to claim 1 , wherein a bonding strength between the battery can and the can joint is greater than a bonding strength between the electrode tab and the tab joint.

18. a press-fit beading portion is formed between the cap plate and the electrode assembly at a periphery of the battery can; The cylindrical secondary battery according to claim 1 , wherein the can joint portion is welded onto a flat region of the beading portion.

19. The cylindrical secondary battery according to claim 18 , wherein the weld bead formed at the can joint is located inside the boundary of the flat region at a distance of 0.1 mm or more.

20. The cylindrical secondary battery of claim 1 , wherein the cap plate is formed with a vent having a thickness equal to or less than 1 / 10 of the thickness of the cap plate.

21. The cylindrical secondary battery according to claim 1 , wherein a height of the main body portion corresponds to a distance between the current collector plate and the cap plate.

22. The cylindrical secondary battery according to claim 1 , wherein the main body does not pressurize the current collector plate.

23. The cylindrical secondary battery according to claim 1 , wherein the sealing portion surrounds an edge portion of the cap plate to insulate the battery can from the cap plate.

24. The cylindrical secondary battery according to claim 1 , wherein the distance between the connecting portion and the cap plate increases as the connecting portion is farther away from the body portion.

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