Ultrasonic welding device and electrode assembly produced thereby

Abstract

An ultrasonic welding device according to an embodiment of the present invention can weld a plurality of electrode tabs of an electrode assembly. The ultrasonic welding device may include an anvil located on one side of the plurality of electrode tabs, a horn facing the anvil with the plurality of electrode tabs interposed therebetween, and a protrusion provided on at least one of the anvil and the horn and facing the plurality of electrode tabs. The protrusion may include an inner protrusion having a plurality of first protrusions arranged along a first direction parallel to a width direction of the electrode tabs, and a pair of outer protrusions located on both sides of the inner protrusion in a second direction perpendicular to the first direction, and having a plurality of second protrusions arranged at a wider interval than the plurality of first protrusions.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0169084, filed November 30, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to an ultrasonic welding device for welding together a plurality of electrode tabs of an electrode assembly, and to an electrode assembly manufactured by the ultrasonic welding device. [Background technology]

[0003] Unlike primary batteries, secondary batteries are rechargeable and have the potential to be small and have large capacities. Due to this, research and development of secondary batteries has been extensive in recent years. With the increasing technological development and demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing.

[0004] Secondary batteries are classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries depending on the shape of the battery case. In secondary batteries, the electrode assembly attached inside the battery case is a chargeable and dischargeable power generating element consisting of a laminated structure of electrodes and separators.

[0005] Electrode assemblies can be broadly classified into a jelly-roll type in which a separator is interposed between a sheet-like positive electrode and a sheet-like negative electrode coated with an active material and wound up, a stack type in which multiple electrodes are stacked in sequence with a separator interposed therebetween, and a stack & folding type in which a stack-type unit cell is wound up with a long separating film.

[0006] In particular, stack-type and stack-and-fold-type electrode assemblies include electrode tabs connected to a plurality of electrodes, and the plurality of electrode tabs are generally welded together using an ultrasonic welding device. However, since the electrode tabs have a thickness of several micrometers, there is a concern that the ultrasonically welded portion may be easily broken due to external disturbances, etc. Therefore, an ultrasonic welding device that can resolve this concern is needed. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION One object of the present invention is to provide an ultrasonic welding device that minimizes the risk of breakage or cracks occurring in a welded portion to which multiple electrode tabs are welded. Another object of the present invention is to provide an electrode assembly manufactured by the ultrasonic welding apparatus. [Means for solving the problem]

[0008] An ultrasonic welding device according to an embodiment of the present invention can weld a plurality of electrode tabs of an electrode assembly. The ultrasonic welding device may include an anvil positioned on one side of the plurality of electrode tabs, a horn facing the anvil with the plurality of electrode tabs interposed therebetween, and protrusions provided on at least one of the anvil and the horn and facing the plurality of electrode tabs. The protrusions may include an inner protrusion having a plurality of first protrusions arranged along a first direction parallel to the width direction of the electrode tabs, and a pair of outer protrusions positioned on both sides of the inner protrusion in a second direction perpendicular to the first direction, and having a plurality of second protrusions arranged at a wider interval than the plurality of first protrusions.

[0009] The length of the protrusion in the first direction may be smaller than the width of the electrode tab. The distance between both ends of the protrusion and both side edges of the electrode tab may be 1 / 45 to 1 / 30 of the width of the electrode tab.

[0010] The length of the inner protrusion in the first direction may be longer than the length of the outer protrusion. The pair of outer protrusions may have a symmetrical shape with respect to the inner protrusion.

[0011] The inner protrusion portion may be arranged such that the first protrusions form a plurality of rows along the first direction. The outer protrusion may have the plurality of second protrusions arranged along an imaginary curve.

[0012] The curve may be a portion of an ellipse. The distance between the inner protrusion and the outer protrusion in the second direction may decrease as they move outward in the first direction.

[0013] The maximum distance between the inner protrusion and the outer protrusion in the second direction may be 0.5 to 0.75 times the width of the inner protrusion in the second direction.

[0014] An electrode assembly according to an embodiment of the present invention may include a plurality of electrodes stacked with separators interposed therebetween, a plurality of electrode tabs connected to the plurality of electrodes, and a welded portion formed by welding the plurality of electrode tabs to each other. The welded portion includes an inner embossed pattern extending in a first direction parallel to the width direction of the electrode tabs, and two welded portions located on both sides of the inner embossed pattern in a second direction perpendicular to the first direction and spaced apart from each other by a wider gap than the inner embossed pattern. A pair of An outer embossed pattern can be formed.

[0015] The welded portion may be provided on a part of both sides in the width direction and may include a flat portion where the inner embossed pattern and the outer embossed pattern are not formed.

[0016] The width of the flat portion may be 1 / 45 to 1 / 30 of the width of the electrode tab. The length of the inner embossed pattern in the first direction may be longer than the length of the outer embossed pattern.

[0017] The pair of outer embossed patterns may have a symmetrical shape with respect to the inner embossed pattern. The inner embossing pattern may be arranged in a plurality of rows along the first direction.

[0018] The outer embossing pattern may be formed along an imaginary curve. The curve may be a portion of an ellipse. A distance between the inner embossed pattern and the outer embossed pattern in the second direction may decrease as they move outward in the first direction.

[0019] The maximum distance between the inner embossed pattern and the outer embossed pattern in the second direction may be 0.5 to 0.75 times the width of the inner embossed pattern in the second direction. [Effects of the Invention]

[0020] According to a preferred embodiment of the present invention, the intervals between the second embossments included in the outer embossed pattern may be greater than the intervals between the first embossments included in the inner embossed pattern, thereby reducing the possibility of breakage or cracks occurring at the welded boundary due to external disturbances and minimizing the expansion of breakage or cracks even if they do occur.

[0021] In addition, the outer embossed pattern may be formed along a curve, which further reduces the possibility of breakage or cracks occurring at the welded boundary due to external disturbances, and minimizes the expansion of breakage or cracks even if they do occur.

[0022] In addition, since the embossed pattern is not formed on a portion of both sides of the welded portion in the width direction, it is possible to minimize the risk of breakage or cracks occurring at the edges of both sides of the welded portion. Other 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 can also be included. [Brief explanation of the drawings]

[0023] 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 concept of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters depicted in the drawings.

[0024] [Figure 1] 1 is a schematic diagram of an ultrasonic welding device according to an embodiment of the present invention. [Figure 2] FIG. 4 is an enlarged view of a protrusion according to an embodiment of the present invention. [Figure 3] FIG. 10 is a perspective view of an electrode assembly according to another embodiment of the present invention. [Figure 4] FIG. 10 is a plan view of a welded portion of an electrode assembly according to another embodiment of the present invention. [Figure 5] FIG. 10 is an enlarged view of a protrusion according to a comparative example of the present invention. [Figure 6] FIG. 10 is a plan view of a welded portion of an electrode assembly according to a comparative example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will now be described in detail with reference to the accompanying drawings, in which preferred embodiments of the present invention can be easily implemented by those skilled in the art, although the present invention may be embodied in various different forms and should not be construed as being limited to the following embodiments.

[0026] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may unnecessarily obscure the gist of the present invention will be omitted, and in this specification, when assigning reference symbols to components in each drawing, the same or similar reference symbols will be assigned to the same or similar components throughout the specification.

[0027] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0028] FIG. 1 is a schematic diagram of an ultrasonic welding device according to one embodiment of the present invention, and FIG. 2 is an enlarged view of a protrusion according to one embodiment of the present invention. The ultrasonic welding device 100 (hereinafter referred to as the welding device) according to this embodiment can weld together the plurality of electrode tabs 13 of the electrode assembly 10. The welding device 100 can weld together the plurality of electrode tabs 13 to form a welded portion 14 (see FIG. 3). That is, the welded portion 14 may be a portion where the plurality of electrode tabs 13 are welded together.

[0029] More specifically, the welding device 100 may include an anvil 110 located on one side of the plurality of electrode tabs 13, a horn 120 facing the anvil 110 with the plurality of electrode tabs 13 therebetween, and a protrusion 130 provided on at least one of the anvil 110 and the horn 120 and facing the plurality of electrode tabs 13.

[0030] The anvil 110 may be positioned below the plurality of electrode tabs 13 and the horn 120 may be positioned above the plurality of electrode tabs 13 . The distance between the anvil 110 and the horn 120 may be adjustable. For example, the horn 120 may be configured so that its distance from the anvil 110 is adjustable. As a result, the electrode tabs 13 may be pressed between the anvil 110 and the horn 120. In this state, the horn 120 vibrates at a high frequency to weld the electrode tabs 13 together. More specifically, ultrasonic waves generated by a vibrator may be amplified by a booster and transmitted to the horn 120. Thus, the horn 120 applies pressure to the electrode tabs 13 placed on the anvil 110 with a certain load, and also applies the amplified ultrasonic waves transmitted from the booster to the electrode tabs 13, thereby welding the electrode tabs 13 together. The configurations and operations of the ultrasonic vibrator and booster are well-known technologies, and therefore detailed description thereof will be omitted.

[0031] The protrusions 130 may be provided on at least one of the anvil 110 and the horn 120. Hereinafter, a case where the protrusions 130 are provided on each of the anvil 110 and the horn 120 will be described as an example.

[0032] Each protrusion 130 may face one of the electrode tabs 13. More specifically, one protrusion 130 may be provided on the bottom surface of the anvil 110, and the other protrusion 130 may be provided on the bottom surface of the horn 120. The protrusion 130 provided on the anvil 110 may face the lower, outermost electrode tab of the electrode tabs 13, and the protrusion 130 provided on the horn 120 may face the upper, outermost electrode tab of the electrode tabs 13. The protrusion 130 provided on the anvil 110 may press the electrode tabs 13 from below, and the protrusion 130 provided on the horn 120 may press the electrode tabs 13 from above.

[0033] The protrusion portion 130 may include a plurality of protrusions 141, 151 protruding toward the electrode tab 13. The plurality of protrusions 141, 151 may include a plurality of first protrusions 141 included in an inner protrusion portion 140 (to be described later) and a plurality of second protrusions 151 included in an outer protrusion portion 150 (to be described later). The first protrusions 141 and the second protrusions 151 may have the same size and shape, but are not limited to this.

[0034] The cross-sectional area of ​​each of the protrusions 141, 151 may become narrower as it approaches the electrode tab 13. For example, each of the protrusions 141, 151 may have a substantially polygonal pyramid shape.

[0035] The welded portion 14 (see FIG. 3) formed by welding the plurality of electrode tabs 13 has the plurality of protrusions. 141 , 151 A plurality of embossed patterns 20, 30 (see FIG. 4) corresponding to the above patterns can be formed, which will be described in detail later.

[0036] More specifically, the protrusion portion 130 may include an inner protrusion portion 140 in which a plurality of first protrusions 141 are arranged along a first direction (a direction parallel to the x-axis in Figure 2) parallel to the width direction of the electrode tab 13, and a pair of outer protrusion portions 150 located on both sides of the inner protrusion portion 140 in a second direction (a direction parallel to the y-axis in Figure 2) perpendicular to the first direction, in which a plurality of second protrusions 151 are arranged at wider intervals than the plurality of first protrusions 141.

[0037] The inner protrusion 140 may be formed by grouping a plurality of first protrusions 141. The inner protrusion 140 may be arranged such that the plurality of first protrusions 141 form at least one row in the first direction. Preferably, the inner protrusion 140 may be arranged such that the plurality of first protrusions 141 form a plurality of rows in the first direction.

[0038] The pair of outer protrusions 150 may have a symmetrical shape with respect to the inner protrusion 140. However, the present invention is not limited to this. Each outer protrusion 150 may be formed by grouping a plurality of second protrusions 151. In each outer protrusion 150, the plurality of second protrusions 151 may be arranged along a virtual curve CL1. That is, each outer protrusion 150 may be formed along the curve CL1. The curve CL1 may form a part of an ellipse.

[0039] The number of rows formed by the plurality of second protrusions 151 may be less than the number of rows formed by the plurality of first protrusions 141. For example, the plurality of second protrusions 151 may be arranged to form one row along the curve CL1, and the plurality of first protrusions 141 may be arranged to form a plurality of rows along the first direction.

[0040] By forming the outer protrusion 150 along the curve CL1, the outer embossed pattern 30 (see FIG. 4), which will be described later, can also be formed along the curve CL2.

[0041] The interval g between the plurality of second protrusions 151 included in the outer protrusion portion 150 may be wider than the interval g between the plurality of first protrusions 141 included in the inner protrusion portion 140. For example, the plurality of first protrusions 141 may not be arranged adjacent to each other to form an interval, and the interval g between the plurality of second protrusions 151 may be equal to or greater than the width of each second protrusion 151.

[0042] In the first direction, the length L11 of the inner protrusion 140 may be longer than the length L12 of the outer protrusion 150. In the first direction, the length L11 of the inner protrusion 140 may refer to the length of the protrusion 130.

[0043] The length of the protrusion 130 in the first direction may be smaller than the width w of the electrode tab 13. That is, the length L11 of the inner protrusion 140 in the first direction may be smaller than the width w of the electrode tab 13.

[0044] More specifically, a predetermined distance d12 may be formed between both ends of the protrusion 130 and both side edges of the electrode tab 13. The distance d12 may be 1 / 45 to 1 / 30 of the width w of the electrode tab 13. For example, the width w of the electrode tab 13 may be about 45 mm, and the distance d12 may be about 1 mm to 1.5 mm.

[0045] This allows the multiple electrode tabs 13 to be reliably welded together, while forming flat portions 14a on both widthwise edges of the welded portion 14 (see Figure 4), which will be described later, without the embossed patterns 20, 30 formed thereon.

[0046] The distance d11 between the inner protrusion 140 and the outer protrusion 150 in the second direction may decrease as they move outward in the first direction. Therefore, the distance d11 between the inner protrusion 140 and the outer protrusion 150 in the second direction may be a maximum distance dm1 at the center of the protrusion 130 in the first direction.

[0047] The maximum distance dm1 between inner protrusion 140 and outer protrusion 150 in the second direction may be 0.5 to 0.75 times the width w1 of inner protrusion 140 in the second direction. For example, the width w1 of inner protrusion 140 may be approximately 4 mm, and the maximum distance dm1 between inner protrusion 140 and outer protrusion 150 may be approximately 2 mm to 3 mm.

[0048] This makes it possible to weld the electrode tabs 13 reliably while preventing the expansion of breaks or cracks that may occur in the welded portion 14 (see FIG. 4) described below.

[0049] FIG. 3 is a perspective view of an electrode assembly according to another embodiment of the present invention, and FIG. 4 is a plan view of a portion to be welded of the electrode assembly according to another embodiment of the present invention. Hereinafter, the electrode assembly 10 manufactured by the ultrasonic welding apparatus 100 will be described as another embodiment of the present invention.

[0050] The electrode assembly 10 according to this embodiment may include a plurality of electrodes 11 stacked with separators 12 interposed therebetween, a plurality of electrode tabs 13 connected to the plurality of electrodes 11, and a welded portion 14 formed by welding the plurality of electrode tabs 13 to each other.

[0051] The electrode 11 may be formed by applying an active material slurry to a metal foil or metal mesh electrode current collector. The electrode 11 may be divided into a positive electrode or a negative electrode, and the positive electrode current collector may include an aluminum material, while the negative electrode current collector may include a copper material. The positive electrode and the negative electrode may be alternately stacked with a separator 12 interposed therebetween.

[0052] The electrode tab 13 protrudes from the electrode 11 and, together with the electrode lead 15 , can act as a path through which electrons can travel between the inside and outside of the electrode assembly 10 . Multiple electrodes 11 Of these, the plurality of electrode tabs 13 connected to the positive electrode and the plurality of electrode tabs 13 connected to the negative electrode may protrude in the same direction relative to the electrode assembly 10, as shown in Fig. 3. However, without being limited thereto, it goes without saying that the plurality of electrode tabs 13 connected to the positive electrode and the plurality of electrode tabs 13 connected to the negative electrode may protrude in opposite directions relative to the electrode assembly 10.

[0053] Some of the electrode tabs 13 can be welded together to form the welded portion 14. The electrode tabs 13 can be closer to each other as they move closer to the welded portion 14 side. The width of the welded portion 14 is determined by the distance between the electrode tabs 13 and the welded portion 14. 13 The welded portion 14 can be formed by the ultrasonic welding device 100 described above.

[0054] An electrode lead 15 may be connected to the plurality of electrode tabs 13, more specifically, to the welded portions 14, by spot welding or the like. When the electrode assembly 10 is housed in a battery case (not shown), one end of the electrode lead 15 is connected to the plurality of electrode tabs 13. 13and the other end may protrude outside the battery case.

[0055] A portion of the electrode lead 15 may be surrounded by an insulating portion 16. For example, the insulating portion 16 may include insulating tape. The insulating portion 16 prevents electricity generated in the electrode assembly 10 from flowing to the battery case via the electrode lead 15. This is a well-known technique, so a detailed description will be omitted.

[0056] 4, embossed patterns 20 and 30 may be formed on the welded portion 14. The embossed patterns 20 and 30 are formed by an ultrasonic welding device. 100 The embossed patterns 20 and 30 may be formed by the protrusions 130. The characteristics of the embossed patterns 20 and 30 may correspond to the characteristics of the protrusions 130 described above.

[0057] The embossed patterns 20 and 30 may include a plurality of embossments 21 and 31. The plurality of embossments 21 and 31 may include a plurality of first embossments 21 included in the inner embossed pattern 20, which will be described later, and a plurality of second embossments 31 included in the outer embossed pattern 30, which will be described later. The first embossments 21 and the second embossments 31 may have the same size and shape, but are not limited to this.

[0058] The embossed patterns 20 and 30 are formed by an ultrasonic welding device. 100 The ultrasonic welding device 10 may include an inner embossed pattern 20 formed by the inner protrusions 140 of the ultrasonic welding device 10 and an outer embossed pattern 30 formed by the outer protrusions 150 of the ultrasonic welding device 10.

[0059] A more detailed description will now be given with reference to both FIG. 2 and FIG. The welded portion 14 may be formed with an inner embossed pattern 20 extending along a first direction (a direction parallel to the x-axis in FIG. 4) parallel to the width direction of the electrode tab 13, and outer embossed patterns 30 positioned on both sides of the inner embossed pattern 20 in a second direction (a direction parallel to the y-axis in FIG. 4) perpendicular to the first direction and formed at a wider interval than the inner embossed pattern 20.

[0060] The inner embossed pattern 20 may be formed by grouping a plurality of first embossments 21. The inner embossed pattern 20 may be arranged such that the plurality of first embossments 21 form at least one row in the first direction. Preferably, the inner embossed pattern 20 may be arranged such that the plurality of first embossments 21 form a plurality of rows in the first direction.

[0061] The pair of outer embossed patterns 30 may have a symmetrical shape with respect to the inner embossed pattern 20. However, this is not limitative. A pair of outer embossed patterns 30 can form a welded boundary.

[0062] Each outer embossed pattern 30 may be formed by grouping a plurality of second embosses 31. In each outer embossed pattern 30, a plurality of second embosses 31 may be arranged along a virtual curve CL2. That is, each outer embossed pattern 30 may be formed along the curve CL2. The curve CL2 may form a part of an ellipse. The curve CL2 may correspond to the curve CL1 formed by the outer protrusion 150 of the ultrasonic welding device 100.

[0063] The number of rows formed by the plurality of second embossments 31 may be smaller than the number of rows formed by the plurality of first embossments 21. For example, the plurality of second embossments 31 may be arranged to form one row along the curve CL2, and the plurality of first embossments 21 may be arranged to form a plurality of rows along the first direction.

[0064] Since the outer embossed pattern 30 is formed along the curve CL2, the welded boundary can be curved. The intervals g2 between the plurality of second embossments 31 included in the outer embossed pattern 30 may be wider than the intervals g1 between the plurality of first embossments 21 included in the inner embossed pattern 20.

[0065] This reduces the risk of breakage or cracks occurring at the welded boundary due to external disturbances, and even if breakage or cracks do occur, the expansion of the breakage or cracks can be limited.

[0066] In the first direction, the length L21 of the inner embossed pattern 20 may be longer than the length L22 of the outer embossed pattern 30. The length L21 of the inner embossed pattern 20 may be the same as or slightly shorter than the length L11 of the inner protrusion 140 of the ultrasonic welding device 100. The length L22 of the outer embossed pattern 30 may be the same as or slightly shorter than the length L12 of the outer protrusion 150 of the ultrasonic welding device 100. The length L21 of the inner embossed pattern 20 in the first direction may refer to the length of the embossed patterns 20, 30.

[0067] The length of the embossed patterns 20, 30 in the first direction may be smaller than the width w of the electrode tab 13. That is, the length L of the inner embossed pattern 20 in the first direction 21 may be smaller than the width w of the welded portion 14.

[0068] The welded portion 14 may include flat portions 14a that are provided on a portion of both sides in the width direction and that do not have the inner embossed pattern 20 and the outer embossed pattern 30. The embossed patterns 20, 30 may not be formed on a portion of both sides in the width direction of the welded portion 14. As a result, the embossed patterns 20, 30 do not invade or are not formed adjacent to both side edges of the welded portion 14 in the width direction, minimizing the risk of damage such as cracks or breaks occurring on both side edges of the welded portion 14 in the width direction.

[0069] The width d22 of the flat portion 14a may be 1 / 45 to 1 / 30 of the width w of the electrode tab 13, i.e., the width w of the welded portion 14. For example, the width w of the electrode tab 13 may be approximately 45 mm, and the width d22 of the flat portion 14a may be 1 mm to 1.5 mm.

[0070] This minimizes the risk of damage such as cracks or breakage occurring at both widthwise edges of the welded portion 14 while maintaining the welded portion 14 in a stable state. If the width d22 of the flat portion 14a is less than 1 / 45 of the width w of the electrode tab 13, the embossed patterns 20, 30 may be excessively adjacent to both widthwise edges of the welded portion 14, potentially causing damage such as cracks or breakage at both widthwise edges of the welded portion 14. Conversely, if the width d22 of the flat portion 14a is more than 1 / 30 of the width w of the electrode tab 13, the welding strength between the multiple electrode tabs 13 may be weak, and the welded portion 14 may not be able to be maintained in a stable state.

[0071] The distance d21 between the inner embossed pattern 20 and the outer embossed pattern 30 in the second direction may decrease as they move outward in the first direction. Therefore, the distance d21 between the inner embossed pattern 20 and the outer embossed pattern 30 in the second direction may be a maximum distance dm2 at the center of the welded portion 14 in the first direction.

[0072] The maximum distance dm2 between the inner embossed pattern 20 and the outer embossed pattern 30 in the second direction may be 0.5 to 0.75 times the width w2 of the inner embossed pattern 20 in the second direction. For example, the width w2 of the inner embossed pattern 20 may be approximately 4 mm, and the maximum distance dm2 between the inner embossed pattern 20 and the outer embossed pattern 30 may be approximately 2 mm to 3 mm.

[0073] This allows the welded portion 14 to be stably maintained while limiting the expansion of breaks or cracks that may occur in the inner embossed pattern 20. If the maximum distance dm2 is less than 0.5 times the width w2 of the inner embossed pattern 20, the line formed by the outer embossed pattern 30 will be closer to a straight line rather than a curve CL2, which may make it difficult to achieve the effect of limiting the expansion of breaks or cracks that may occur in the inner embossed pattern 20. Conversely, if the maximum distance dm2 is more than 0.75 times the width w2 of the inner embossed pattern 20, the arrangement density per unit area of ​​the embossed patterns 20, 30 will be excessively low, which may weaken the welding force between the multiple electrode tabs 13 and make it difficult to maintain the welded portion 14 stably.

[0074] FIG. 5 is an enlarged view of a protrusion according to a comparative example of the present invention, and FIG. 6 is a plan view of a welded portion of an electrode assembly according to a comparative example of the present invention. 5 and 6, the length L of the protrusion 130' according to the comparative example may be equal to or greater than the width w of the welded portion 14'. Therefore, the embossed pattern 20' formed on the welded portion 14' by the protrusion 130' may penetrate or be adjacent to both widthwise edges of the welded portion 14'. This increases the likelihood of damage, such as cracks or breaks, occurring on both widthwise edges of the welded portion 14'.

[0075] In addition, the plurality of protrusions 131' included in the protruding portion 130' may be arranged at regular intervals. Accordingly, the plurality of embossments 21' included in the embossed pattern 20' formed on the welded portion 14' may also be arranged at regular intervals, and the welded boundary may form a straight line.

[0076] Therefore, there is a problem that breaks or cracks are likely to occur at the boundaries of the embossed pattern 20', and the breaks or cracks can quickly expand. Those skilled in the art will be able to more easily understand the configuration and effects of the present invention from such comparative examples.

[0077] The above description is merely an illustrative example of the technical concept of the present invention, and various modifications and variations are possible within the scope of the essential characteristics of the present invention, by those having ordinary knowledge in the technical field to which the present invention pertains.

[0078] Therefore, the embodiments disclosed in the present invention are intended to illustrate, 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.

[0079] The scope of protection of the present invention should be interpreted by the following claims, 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]

[0080] 10: Electrode assembly 11: Electrode 12: Separator 13: Electrode tab 14: Welded part 15: Electrode lead 20: Inner embossing pattern 21: First Emboss 30: Outer embossed pattern 31: Second embossing 100: Ultrasonic welding equipment 110: Anvil 120: Horn 130:Protrusion 140: Inner protrusion 141:1st protrusion 150: Outer protrusion 151:Second protrusion

Claims

1. An ultrasonic welding device for welding a plurality of electrode tabs of an electrode assembly, comprising: an anvil located on one side of the plurality of electrode tabs; a horn facing the anvil with the plurality of electrode tabs therebetween; a protrusion on at least one of the anvil and the horn, the protrusion extending toward the plurality of electrode tabs; Including, The protrusion is an inner protrusion portion having a plurality of first protrusions arranged along a first direction parallel to the width direction of the electrode tab; a pair of outer protrusions located on both sides of the inner protrusion in a second direction perpendicular to the first direction, the outer protrusions including a plurality of second protrusions arranged at intervals wider than the intervals between the plurality of first protrusions; Including, a distance between the inner protrusion and the outer protrusion in the second direction decreases toward the outside in the first direction; The maximum distance between the inner protrusion and the outer protrusion in the second direction is 0.5 to 0.75 times the width of the inner protrusion in the second direction. Ultrasonic welding equipment.

2. The ultrasonic welding device according to claim 1 , wherein the length of the protrusion in the first direction is smaller than the width of the electrode tab.

3. 3. The ultrasonic welding device according to claim 2, wherein the distance between each end of the protrusion and each of the two side edges of the electrode tab is 1 / 45 to 1 / 30 of the width of the electrode tab.

4. The ultrasonic welding device according to claim 1 , wherein a length of the inner protrusion in the first direction is longer than a length of the outer protrusion.

5. The ultrasonic welding device according to claim 1 , wherein the pair of outer projections have a symmetrical shape with respect to the inner projection.

6. The ultrasonic welding device according to claim 1 , wherein the inner protrusion portion has the plurality of first protrusions arranged in a plurality of rows along the first direction.

7. The ultrasonic welding device according to claim 1 , wherein the outer protrusion portion has the plurality of second protrusions arranged along an imaginary curve.

8. The ultrasonic welding apparatus of claim 7 , wherein the curve is a portion of an ellipse.

9. A plurality of electrodes stacked with separators interposed therebetween; a plurality of electrode tabs connected to the plurality of electrodes; a welded portion formed by welding the plurality of electrode tabs to each other; Including, The welded portion has an inner embossed pattern extending along a first direction parallel to a width direction of the electrode tab; a pair of outer embossed patterns located on both sides of the inner embossed pattern in a second direction perpendicular to the first direction and formed at a wider interval than the inner embossed patterns; is formed, a distance between the inner embossed pattern and the outer embossed pattern in the second direction decreases toward the outside in the first direction; a maximum distance between the inner embossed pattern and the outer embossed pattern in the second direction is 0.5 to 0.75 times the width of the inner embossed pattern in the second direction; Electrode assembly.

10. The welded portion is The electrode assembly according to claim 9 , further comprising flat portions provided on both sides in the width direction, where the inner embossed pattern and the outer embossed pattern are not formed.

11. The electrode assembly of claim 10, wherein the width of the flat portion is 1 / 45 to 1 / 30 of the width of the electrode tab.

12. The electrode assembly of claim 9 , wherein a length of the inner embossed pattern in the first direction is longer than a length of the outer embossed pattern.

13. The electrode assembly according to claim 9 , wherein the pair of outer embossed patterns have a symmetrical shape with respect to the inner embossed pattern.

14. The electrode assembly of claim 9 , wherein the inner embossed patterns form a plurality of rows along the first direction.

15. The electrode assembly according to claim 9 , wherein the outer embossing pattern is formed along an imaginary curve.

16. The electrode assembly of claim 15 , wherein the curve is a portion of an ellipse.

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