Ultrasonic welding device and welding structure

Abstract

According to one embodiment of the present invention, an ultrasonic welding apparatus comprises: a welding head for pressing a first member to ultrasonically weld the first member to a second member, in which the welding head comprises a knurled portion having a plurality of protrusions protruding toward the first member to create a concave-convex shape on the first member, and the protrusions located in the outermost region of the knurled portion and the protrusions located in the inner region of the knurled portion have different shapes.

Description

Technical Field

[0001] The present invention relates to an ultrasonic welding device and a welding structure using the ultrasonic welding device.

[0002] This application claims priority to Korean Patent Application No. 10-2022-0183127 filed in Korea on December 23, 2022, the disclosure of which is incorporated herein by reference. Background Art

[0003] As an energy source for electronic devices such as mobile phones, laptop computers, and wearable devices or electric vehicles, the demand for secondary batteries is increasing. Secondary batteries are classified into nickel-cadmium secondary batteries, nickel-hydrogen secondary batteries, and lithium secondary batteries according to the type of electrode, and lithium secondary batteries with advantages such as high operating voltage and high energy density per unit weight are currently being actively researched and developed.

[0004] Lithium secondary batteries are classified into square secondary batteries and cylindrical secondary batteries according to the shape of a battery case, in which an electrode assembly is accommodated in a metal can, and pouch-type secondary batteries, in which an electrode assembly is accommodated in a pouch case made of an aluminum laminate.

[0005] In addition, when the cylindrical battery is inserted, the terminal provided on the closed portion of the battery can can pass through the closed portion and contact the collector plate provided in the battery can. Therefore, the contact portion between the collector plate and the terminal can be welded by performing ultrasonic welding while the welding corner contacts the collector plate in the battery can.

[0006] As described above, the current collector plate and the terminal may be connected, for example, by ultrasonic welding, and the ultrasonic welding device uses an anvil on which the terminal is placed and a horn that presses the current collector plate.

[0007] The existing welding head has a structure including a plurality of protrusions to increase friction and pressure. However, according to this structure, the pressing force at the outermost point of the welding area may generate burrs and / or foreign matter on the upper member, and if used without separate treatment, the burrs and / or foreign matter remaining inside the battery may affect performance. Summary of the invention

[0008] Technical issues

[0009] The present disclosure has been designed to solve the problems of the related art, and thus the present disclosure is directed to providing an ultrasonic welding device configured to prevent burrs and / or foreign matter from being generated on an object to be welded when performing ultrasonic welding.

[0010] In another aspect, the present disclosure provides a structure including a plurality of welded stacked objects in which burrs and / or foreign matter are not generated.

[0011] In another aspect, the present disclosure also provides a structure including a plurality of welded stacked objects having burrs and / or foreign objects that are equal to or smaller than a specific size or a specific number.

[0012] On the other hand, the present disclosure is also intended to enhance the internal performance of a battery and ensure stable battery performance by preventing the generation of burrs and / or foreign matter.

[0013] However, technical problems that the present disclosure is intended to solve are not limited to the above problems, and other problems not mentioned above will be clearly understood by those skilled in the art from the description of the present invention described below.

[0014] Technical Solution

[0015] According to one aspect of the present disclosure, an ultrasonic welding device is provided, comprising: a welding head, wherein the welding head is configured to press a first member to ultrasonically weld the first member and a second member, wherein the welding head comprises a knurled portion having a plurality of protrusions to produce an uneven shape on the first member, the plurality of protrusions being configured to protrude toward the first member, and wherein the shape of the protrusions located in the outermost area of ​​the knurled portion is different from the shape of the protrusions located in the inner area of ​​the knurled portion.

[0016] Preferably, the protrusion may be configured such that a cross-sectional area of ​​the protrusion gradually decreases toward the first member.

[0017] According to one aspect of the present disclosure, a first width of the protrusion at an end point of the protrusion may be smaller than a second width of the protrusion at a point where the protrusion starts to protrude.

[0018] According to another aspect of the present disclosure, the first width of the protrusion located in the outermost region of the knurled portion may be configured to be greater than the first width of the protrusion located in the inner region of the knurled portion.

[0019] Preferably, the first width of the protrusion located in the outermost region of the knurled portion may be configured to be within a range of 1.2 to 1.8 times the first width of the protrusion located in the inner region of the knurled portion.

[0020] According to another aspect of the present disclosure, the second width of the protrusion located in the outermost region of the knurled portion may be less than or equal to the second width of the protrusion located in the inner region of the knurled portion.

[0021] Preferably, the second width of the protrusion located in the outermost region of the knurled portion may be configured to be within a range of 0.4 to 1.0 times the second width of the protrusion located in the inner region of the knurled portion.

[0022] According to another aspect of the present disclosure, a height of the protrusions located in the outermost region of the knurled portion may be smaller than a height of the protrusions located in the inner region of the knurled portion.

[0023] According to another aspect of the present disclosure, the protrusion may be configured to have a trapezoidal shape in a longitudinal cross-section of the protrusion.

[0024] According to one embodiment of the present disclosure, a structure is provided including a plurality of stacked objects to be welded, wherein the plurality of stacked objects can be ultrasonically welded, wherein a plurality of indentations can be formed on outer surfaces of the plurality of stacked objects by ultrasonic welding, and wherein the width of the indentations in an outermost region among the plurality of indentations can be greater than the width of the indentations in an inner region.

[0025] According to another embodiment of the present disclosure, a structure is provided including a plurality of stacked objects to be welded, wherein the plurality of stacked objects can be ultrasonically welded, wherein a plurality of indentations can be formed on outer surfaces of the plurality of stacked objects by ultrasonic welding, and wherein the depth of the indentations in an outermost area among the plurality of indentations can be smaller than the depth of the indentations in an inner area.

[0026] Here, the structure including the plurality of stacked objects to be welded may be a cylindrical battery.

[0027] In particular, the plurality of stacked objects to be welded may be terminals and collectors included in a cylindrical battery.

[0028] Beneficial Effects

[0029] According to the present disclosure, it is possible to prevent burrs and / or foreign matter from being generated on an object to be welded when ultrasonic welding is performed.

[0030] On the other hand, according to the present disclosure, it is possible to enhance the internal performance of a battery and ensure stable battery performance by preventing the generation of burrs and / or foreign matter.

[0031] However, effects obtainable from the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned above will be clearly understood by those skilled in the art from the description of the present invention described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the detailed description of the present invention, serve to provide further understanding of the technical concept of the present disclosure, and therefore, the present disclosure is not to be construed as being limited to the accompanying drawings.

[0033] Figure 1 is a diagram showing an ultrasonic welding device and an object to be welded according to an embodiment of the present disclosure.

[0034] Figure 2 is a diagram illustrating an ultrasonic welding process of an ultrasonic welding device according to an embodiment of the present disclosure.

[0035] Figure 3 is a diagram showing a horn included in an ultrasonic welding device according to an embodiment of the present disclosure.

[0036] Figure 4 is a diagram illustrating an ultrasonic welding device and a first member according to an embodiment of the present disclosure.

[0037] Figure 5 is a diagram showing the structure of a conventional welding head.

[0038] Figure 6 is a diagram showing a process of ultrasonically welding a first member and a second member using a conventional horn.

[0039] Figure 7 is a diagram showing the structure of a welding head according to one embodiment of the present disclosure.

[0040] Figure 8 is a diagram showing the structure of a welding head according to another embodiment of the present disclosure.

[0041] Fig. 9 is a diagram illustrating a process of ultrasonically welding a first member and a second member using a horn according to an embodiment of the present disclosure.

[0042] Fig.10 : is a graph comparing the total amount of foreign matter generated by ultrasonic welding using a conventional horn and the total amount of foreign matter generated by ultrasonic welding using a horn according to an embodiment of the present disclosure.

[0043] Fig.11 is a diagram illustrating an ultrasonic welding system according to an embodiment of the present disclosure.

[0044] Fig.12is a diagram illustrating a first collecting electrode included in an ultrasonic welding system according to an embodiment of the present disclosure.

[0045] Fig.13 is along Fig.12 Schematic cross-sectional view taken along line CC' in FIG. DETAILED DESCRIPTION

[0046] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general and dictionary meanings, but should be interpreted based on the meanings and concepts corresponding to the technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to appropriately define the terms to obtain the best interpretation.

[0047] Therefore, the embodiments of this specification and the configurations proposed in the drawings only represent the most preferred embodiments of the present disclosure and do not represent all technical concepts of the present disclosure, and therefore it should be understood that various equivalents and modifications may be made thereto when an application is filed.

[0048] In addition, to help understand the present disclosure, the drawings are not drawn to true scale and the sizes of some elements may be exaggerated.

[0049] Figure 1 is a diagram showing an ultrasonic welding device 3 and an object to be welded according to an embodiment of the present disclosure, and Figure 2 is a diagram illustrating an ultrasonic welding process of the ultrasonic welding device 3 according to an embodiment of the present disclosure.

[0050] Reference Figure 1 and Figure 2 , the ultrasonic welding device 3 according to the present disclosure includes a horn 5. The horn 5 may be formed into an uneven shape on the first member S1. The horn 5 may press the first member S1 with a predetermined weight while in contact with the first member S1, and also apply ultrasonic waves, thereby ultrasonically welding the first member S1 and the second member S2. That is, the horn 5 may press the first member S1 to ultrasonically weld the first member S1 and the second member S2. The horn 5 may include a knurled portion N having a plurality of protrusions T configured to protrude toward the first member S1. The plurality of protrusions T may press the first member S1 with a predetermined weight while in contact with the first member S1 and apply ultrasonic waves, thereby performing ultrasonic welding of the first member S1 and the second member S2. However, the present disclosure is not limited to an example in which only the first member S1 and the second member S2 are ultrasonically welded. That is, the ultrasonic welding device 3 according to the present disclosure may ultrasonically weld two or more members.

[0051] Reference Figure 2In order to perform ultrasonic welding, the plurality of protrusions T need to press the upper member S1 with a predetermined weight in a state of contact with the upper member S1 of the object to be welded while applying ultrasonic waves.

[0052] Figure 3 is a diagram showing a horn 5 included in an ultrasonic welding device 3 according to an embodiment of the present disclosure. Figure 4 is a diagram showing an ultrasonic welding device 3 and a first member S1 according to an embodiment of the present disclosure.

[0053] Reference Figure 3 and Figure 4 , the plurality of protrusions T may be arranged at regular intervals n. The plurality of protrusions T may be arranged at regular intervals n along the X-axis and the Y-axis between adjacent protrusions T. The plurality of protrusions T may have a square shape. For example, the plurality of protrusions T may be arranged so that adjacent protrusions T are as follows: Figure 3 point contact with each other as shown in (a) or as Figure 3 In this case, the regular interval n may be a distance between the front ends of adjacent protrusions T protruding in the -Z axis direction.

[0054] Each of the plurality of protrusions T may be configured so that the cross-sectional area gradually decreases toward the first member S1 (in the -Z axis direction). For example, in a case where the width of the protrusion T at the end point of the protrusion T is the first width A and the width of the protrusion T at the point where the protrusion T begins to protrude is the second width B, the first width A may be configured to be smaller than the second width B. In this case, the first width A and the second width B represent the width of the cut surface obtained by cutting the protrusion T along a plane perpendicular to the protruding direction of the protrusion T and including the end point of the protrusion T. That is, the protrusion T may be configured to have a trapezoidal cross section.

[0055] In another aspect of the present disclosure, each of the plurality of protrusions T may have an inclination of a predetermined angle θ relative to the first member S1. For example, in the case where each of the plurality of protrusions T is configured as a rectangular pyramid, the edge of the rectangular pyramid and the XY plane may form a predetermined angle θ therebetween. As an example, each of the plurality of protrusions T may be configured as Figure 4 The rectangular pyramid shown, and the angle between the edge of the rectangular pyramid and the XY plane can be about 30 degrees to about 60 degrees.

[0056] According to the structure of the present disclosure, the arrangement of the plurality of protrusions T can be changed according to the friction force required for ultrasonic welding. For example, if a large friction force is required, the plurality of protrusions T can be arranged so that the predetermined angle θ increases and the regular interval n decreases, thereby increasing the density of the plurality of protrusions T in the knurled portion N, and if a small friction force is required, the plurality of protrusions T can be arranged so that the predetermined angle θ decreases and the regular interval n increases, thereby reducing the density of the plurality of protrusions T in the knurled portion N.

[0057] In another aspect of the present disclosure, referring to Figure 3 and Figure 4 , the plurality of protrusions T may be configured to have a flat surface obtained by cutting the end protruding toward the first member S1 along a plane parallel to the first member S1 by a predetermined length l. Here, the predetermined length l may be a vertical distance along the -Z axis direction from the flat surface formed by cutting the end to the front end before cutting.

[0058] Each of the plurality of protrusions T may be configured as a polygonal pyramid formed by cutting the end of the polygonal pyramid by a predetermined length along a plane parallel to the XY plane. For example, each of the plurality of protrusions T may be a rectangular pyramid. Alternatively, as another embodiment, each protrusion T may be a truncated cone formed by cutting the end of a cone by a predetermined length along a plane parallel to the XY plane. Figure 4 , the protrusion T may be configured as a shape obtained by cutting a substantially polygonal pyramid or cone structure having a height m along a plane parallel to the first member S1. The cutting position may be spaced apart from the vertex of the substantially polygonal pyramid or cone by a length l in a direction perpendicular to the first member S1. Therefore, the total height h of the protrusion T may be ml.

[0059] According to the structure of the present disclosure, when welding a thin upper member S1, the upper member S1 can be prevented from being damaged or torn due to the plurality of sharp protrusions T. In addition, the contact area between the plurality of protrusions T and the upper member can be controlled by adjusting the predetermined length l to be cut according to the friction force required for ultrasonic welding.

[0060] Figure 5 is a diagram showing the structure of a conventional welding head 5, and Figure 6 1 is a diagram showing a process of ultrasonically welding a first member S1 and a second member S2 using a conventional horn 5 .

[0061] Reference Figure 5, the conventional welding head 5 may include a knurled portion N having a plurality of protrusions T so as to produce an uneven shape on the first member S1, and the plurality of protrusions T are configured to protrude toward the first member S1. Here, the shape of the protrusions T of the knurled portion N is constant regardless of their position. That is, the knurling pattern of the conventional welding head 5 is configured to be a constant shape, such as Figure 5 shown.

[0062] If ultrasonic welding is performed using a conventional horn 5, such as Figure 6 As shown, due to the pressing force, plastic deformation occurs at the outermost point of the knurled portion N in the first member S1. This may cause burrs or foreign matter such as metal particles. Therefore, if the first member S1 and the second member S2 are components arranged inside the battery, the foreign matter will remain inside the battery. Residual foreign matter is a potential risk factor such as short circuit and is the main reason that greatly affects battery performance. Therefore, according to the conventional welding head 5, burrs or foreign matter such as metal particles are likely to be generated, so there is a potential risk such as short circuit. That is, using a conventional welding head 5 to weld the first member S1 and the second member S2 may have a significant impact on the degradation of battery performance.

[0063] Figure 7 is a diagram showing the structure of a welding head 5 according to one embodiment of the present disclosure, and Figure 8 is a diagram showing the structure of a welding head 5 according to another embodiment of the present disclosure. Fig. 9 is a diagram showing a process of ultrasonically welding a first member S1 and a second member S2 using the horn 5 according to an embodiment of the present disclosure.

[0064] In one aspect of the present disclosure, the shape of protrusions T1 located in the outermost region of the knurled portion N may be configured differently from the shape of protrusions T2 located in the inner region of the knurled portion N.

[0065] For example, refer to Figure 7 , the first width A1 of the protrusion T1 located in the outermost area of ​​the knurled portion N may be configured to be greater than the first width A2 of the protrusion T2 located in the inner area of ​​the knurled portion N. Preferably, the first width A1 of the protrusion T1 located in the outermost area of ​​the knurled portion N may be configured to be within a range of about 1.2 times to 1.8 times the first width A2 of the protrusion T2 located in the inner area of ​​the knurled portion N. More preferably, the first width A1 of the protrusion T1 located in the outermost area of ​​the knurled portion N may be configured to be within a range of about 1.3 times to 1.5 times the first width A2 of the protrusion T2 located in the inner area of ​​the knurled portion N.

[0066] According to this structure, Fig. 9As shown, during welding, due to the reduction of plastic deformation caused by the pressing force in the outermost area of ​​the knurled portion N, the effect of preventing the generation of burrs and foreign matter can be obtained. Therefore, if the first member S1 and the second member S2 are elements provided inside the battery, the internal performance of the battery can be enhanced by preventing foreign matter and ensuring stable battery performance.

[0067] That is, the structure including a plurality of objects to be welded stacked with the first member S1 and the second member S2 can be configured so that the plurality of stacked objects are ultrasonically welded, so that a plurality of indentations are formed on the outer surfaces of the plurality of stacked objects by ultrasonic welding, and so that the width of the indentation in the outermost region among the plurality of indentations is greater than the width of the indentation in the inner region. In this structure, the generation of burrs and foreign matter can be minimized.

[0068] As another embodiment of the present disclosure, refer to Figure 8 , the second width B1 of the protrusion T1 located in the outermost area of ​​the knurled portion N may be less than or equal to the second width B2 of the protrusion T2 located in the inner area of ​​the knurled portion N. Preferably, the second width B1 of the protrusion T1 located in the outermost area of ​​the knurled portion N may be configured to be within a range of about 0.4 times to 1.0 times the second width B2 of the protrusion T2 located in the inner area of ​​the knurled portion N. More preferably, the second width B1 of the protrusion T1 located in the outermost area of ​​the knurled portion N may be configured to be within a range of about 0.4 times to 0.6 times the second width B2 of the protrusion T2 located in the inner area of ​​the knurled portion N.

[0069] According to this structure, Fig. 9 As shown, during welding, due to the reduction of plastic deformation caused by the pressing force in the outermost area of ​​the knurled portion N, the effect of preventing the generation of burrs and foreign matter can be obtained. Therefore, if the first member S1 and the second member S2 are elements provided inside the battery, the internal performance of the battery can be enhanced by preventing foreign matter and ensuring stable battery performance.

[0070] That is, the structure including a plurality of objects to be welded stacked with the first member S1 and the second member S2 can be configured so that the plurality of stacked objects are ultrasonically welded, so that a plurality of indentations are formed on the outer surfaces of the plurality of stacked objects by ultrasonic welding, and so that the depth of the indentation in the outermost region among the plurality of indentations is less than the depth of the indentation in the inner region. In this structure, the generation of burrs and foreign matter can be minimized.

[0071] In another aspect of the present disclosure, referring to Figure 8 , the height h1 of the protrusion T1 located in the outermost area of ​​the knurled portion N can be configured to be smaller than the height h2 of the protrusion T2 located in the inner area of ​​the knurled portion N. According to this structure, Fig. 9 As shown, during welding, due to the reduction of plastic deformation caused by the pressing force in the outermost area of ​​the knurled portion N, the effect of preventing the generation of burrs and foreign matter can be obtained.

[0072] In another aspect of the present disclosure, referring to Figure 7 and Figure 8 , the inclination angle of the protrusion T1 located in the outermost area of ​​the knurled portion N can be configured to be the same as the inclination angle of the protrusion T2 located in the inner area of ​​the knurled portion N.

[0073] For example, refer to Figure 7 Since the first width A1 of the protrusion T1 located in the outermost area of ​​the knurled portion N is configured to be greater than the first width A2 of the protrusion T2 located in the inner area of ​​the knurled portion N, and since the inclination angle of the protrusion T1 located in the outermost area of ​​the knurled portion N is the same as the inclination angle of the protrusion T2 located in the inner area of ​​the knurled portion N, the height h1 of the protrusion T1 located in the outermost area of ​​the knurled portion N can be smaller than the height h2 of the protrusion T2 located in the inner area of ​​the knurled portion N.

[0074] In addition, refer to Figure 8 Since the second width B1 of the protrusion T1 located in the outermost area of ​​the knurled portion N is less than or equal to the second width B2 of the protrusion T2 located in the inner area of ​​the knurled portion N, and since the inclination angle of the protrusion T1 located in the outermost area of ​​the knurled portion N is the same as the inclination angle of the protrusion T2 located in the inner area of ​​the knurled portion N, the height h1 of the protrusion T1 located in the outermost area of ​​the knurled portion N can be smaller than the height h2 of the protrusion T2 located in the inner area of ​​the knurled portion N.

[0075] According to this structure, Fig. 9 As shown, during welding, due to the reduction of plastic deformation caused by the pressing force in the outermost area of ​​the knurled portion N, the effect of preventing the generation of burrs and foreign matter can be obtained.

[0076] In another aspect of the present disclosure, the position of the point where the cross-sectional area of ​​the protrusion T1 located in the outermost region of the knurled portion N begins to decrease may be different from the position of the point where the cross-sectional area of ​​the protrusion T2 located in the inner region of the knurled portion N begins to decrease.

[0077] For example, refer to Figure 8, the point where the cross-sectional area of ​​the protrusion T1 located in the outermost region of the knurled portion N begins to decrease may be located at a point vertically away from the horn 5 by a distance k, and the point where the cross-sectional area of ​​the protrusion T2 located in the inner region of the knurled portion N begins to decrease may be located on the surface of the horn 5. That is, the point where the cross-sectional area of ​​the protrusion T1 located in the outermost region of the knurled portion N begins to decrease may be spaced apart from the point where the cross-sectional area of ​​the protrusion T2 located in the inner region of the knurled portion N begins to decrease by a distance k.

[0078] According to this structure, Fig. 9 As shown, during welding, due to the reduction of plastic deformation caused by the pressing force in the outermost area of ​​the knurled portion N, the effect of preventing the generation of burrs and foreign matter can be obtained. Therefore, if the first member S1 and the second member S2 are elements provided inside the battery, the internal performance of the battery can be enhanced by preventing foreign matter and ensuring stable battery performance.

[0079] In order to verify the above-mentioned effect, the inventors performed ultrasonic welding using the conventional horn 5 and the horn 5 of the present disclosure, and measured the total amount of foreign matter generated therefrom.

[0080] first, Figure 5 The conventional welding head 5 shown corresponding to the comparative example is configured to include a knurled portion N including a protrusion T of a predetermined shape having a first width A of 0.14 mm and a second width B of 0.6 mm. Next, Figure 7 The welding head 5 shown corresponding to Example 1 of the present disclosure is configured so that the first width A1 of the protrusion T1 located in the outermost area of ​​the knurled portion N is 0.14 mm, and the first width A2 of the protrusion T2 located in the inner area of ​​the knurled portion N is 0.10 mm. The second width B is set to 0.6 mm regardless of the position of the protrusion T. In addition, Figure 8 The horn 5 shown corresponding to Example 2 of the present disclosure is configured so that the second width B1 of the protrusion T1 located in the outermost area of ​​the knurled portion N is 0.4 mm, and the second width B2 of the protrusion T2 located in the inner area of ​​the knurled portion N is 0.8 mm. The first width A is set to 0.18 mm regardless of the position of the protrusion T. In addition, ultrasonic welding of the first member S1 and the second member S2 was performed using the above-mentioned horn 5 under the conditions of energy of 15 J, pressure of 3 bar, and amplitude of 50%. Fig.10 The total amount of foreign matter generated in each case is shown in FIG.

[0081] Fig.10 : is a graph comparing the total amount of foreign matter generated by ultrasonic welding using a conventional horn 5 and the total amount of foreign matter generated by ultrasonic welding using a horn 5 according to an embodiment of the present disclosure.

[0082] Reference Fig.10 , it can be seen that due to ultrasonic welding using the conventional horn 5, a total of about 42 foreign objects were generated. On the other hand, it can be seen that due to ultrasonic welding using the horn 5 according to the embodiment of the present disclosure, a total of about 24 foreign objects were generated in Example 1 and a total of about 32 foreign objects were generated in Example 2. That is, according to the embodiment of the present disclosure, it was confirmed that the total amount of foreign objects was reduced by about 57% to 76% compared with the conventional ultrasonic welding device 3.

[0083] That is, it can be seen from the above experimental results that according to the present disclosure, during welding, due to the reduction of plastic deformation caused by the pressing force in the outermost area of ​​the knurled portion N, the effect of preventing the generation of burrs and foreign matter can be obtained. Therefore, if the first member S1 and the second member S2 are elements provided inside the battery, the internal performance of the battery can be enhanced by preventing foreign matter and ensuring stable battery performance.

[0084] In one aspect of the present disclosure, the structure including the plurality of stacked objects to be welded may be a cylindrical battery. More specifically, the plurality of stacked objects to be welded may be a terminal and a collector included in the cylindrical battery.

[0085] Fig.11 is a diagram showing an ultrasonic welding system 1 according to an embodiment of the present disclosure. Fig.12 is a diagram showing a first collecting electrode included in the ultrasonic welding system 1 according to an embodiment of the present disclosure. Fig.13 is along Fig.12 Schematic cross-sectional view taken along line CC' in FIG.

[0086] Reference Figures 11 to 13 , an ultrasonic welding system 1 according to the present disclosure may include an electrode assembly 10 , a collecting electrode 30 , a terminal 40 , and an ultrasonic welding device 3 .

[0087] The electrode assembly 10 may include a first electrode having a first polarity, a second electrode having a second polarity, and a separator interposed between the first electrode and the second electrode. The first electrode may be a negative electrode or a positive electrode, and the second electrode may have a polarity opposite to that of the first electrode. The electrode assembly 10 may be manufactured by winding a laminate formed by sequentially stacking a first electrode, a separator, a second electrode, and a separator at least once. That is, the electrode assembly 10 applied to the present disclosure may be a core-wound electrode assembly 10.

[0088] Such a jelly jelly type electrode assembly 10 may have a central hole C formed substantially at the center of the jelly jelly type electrode assembly 10 and extending in a height direction (a direction parallel to the Z axis).

[0089] The first electrode may include a first electrode plate and a first electrode active material layer formed by applying a first electrode active material on at least one surface of the first electrode plate. The second electrode may include a second electrode plate and a second active material layer formed by applying a second electrode active material on at least one surface of the second electrode plate. The first electrode may include a first uncoated portion 11 in which no positive electrode active material or negative electrode active material is coated on the electrode plate. The second electrode may include a second uncoated portion in which no positive electrode active material or negative electrode active material is coated on the electrode plate. At least a portion of the first uncoated portion 11 may be used as a first electrode tab, and at least a portion of the second uncoated portion 11 may be used as a second electrode tab.

[0090] In addition, at least a portion of the first uncoated portion 11 may include a plurality of segments divided along the winding direction of the electrode assembly 10. In this case, the plurality of segments may be bent in the radial direction of the electrode assembly 10. The plurality of bent segments may overlap in a plurality of layers. In this case, the collector 30, which will be described later, may be coupled to the region where the plurality of segments overlap in a plurality of layers.

[0091] The collector 30 may be coupled to one side of the electrode assembly 10. The collector 30 may include a first coupling portion 31 coupled to the electrode assembly 10 and a second coupling portion 32 coupled to a terminal 40 to be described later.

[0092] The first coupling portion 31 may be provided at one side of the electrode assembly 10. The first coupling portion 31 may be coupled to the first uncoated portion 11. The first coupling portion 31 may be coupled to the first uncoated portion 11 by laser welding. The first coupling portion 31 may have a laser welding portion L coupled to the first uncoated portion 11 by laser welding. A plurality of first coupling portions 31 may be provided.

[0093] The second coupling portion 32 may be coupled to the terminal 40. The second coupling portion 32 may be coupled to the terminal 40 by ultrasonic welding. The second coupling portion 32 may have an ultrasonic welding portion U coupled to the terminal 40. For example, the entire second coupling portion 32 may be the ultrasonic welding portion U, and a substantially central portion of the second coupling portion 32 may be the ultrasonic welding portion U.

[0094] At least a portion of the second coupling portion 32 may be formed thinner than the first coupling portion 31 . The relatively thin reduced thickness region may include an ultrasonic welding portion U. The reduced thickness region may have a thickness of about 50% or more and less than 90% of the thickness of the first coupling portion 31 .

[0095] The terminal 40 includes a terminal exposure portion 41 and a terminal insertion portion 42. The terminal exposure portion 41 is exposed to the outside of the battery case. The terminal exposure portion 41 may be located substantially at the center of the closed portion of the case 20.

[0096] The terminal insertion portion 42 may be coupled to the second coupling portion 32 of the current collector 30. The terminal insertion portion 42 may be coupled to the current collector 30 at a position corresponding to the central hole C of the electrode assembly 10 by ultrasonic welding.

[0097] The collector 30 and the terminal 40 can be welded by ultrasonic welding. Ultrasonic welding requires less expensive equipment and causes less thermal deformation than laser welding. In addition, laser welding may damage the diaphragm of the electrode assembly due to the heat generated, while ultrasonic welding is advantageous because there is no such risk. In addition, during the welding process, laser welding requires the size of the center hole C to be larger than a certain size in order to ensure laser focusing, but ultrasonic welding can be performed by inserting a welding head 5 corresponding to the size of the center hole C.

[0098] The ultrasonic welding device 3 may ultrasonically weld the collector 30 and the terminal 40. That is, the collector may correspond to the first member S1, and the terminal may correspond to the second member S2. The ultrasonic welding device 3 may include a horn 5 that presses the collector 30. The ultrasonic welding device 3 may include an anvil 7 that supports the terminal 40. The ultrasonic welding device 3 may have a plurality of protrusions T that protrude toward the collector 30, and each protrusion has a protruding length equal to or greater than the thickness of the collector 30. The thickness of the collector 30 may indicate the thickness of the portion of the collector 30 where ultrasonic welding is performed. That is, it may indicate the thickness of the ultrasonic welding portion U of the second coupling portion 32 of the collector 30. The horn 5 of the ultrasonic welding device 3 may be inserted into the center hole C of the electrode assembly 10 to perform welding between the collector 30 and the terminal 40.

[0099] In addition, according to ultrasonic welding, the upper member and the lower member are welded by recrystallization of plastic flow. Therefore, if the second coupling portion 32 is too thick, plastic flow may not occur effectively. Fig.13 As shown, preferably, the second coupling portion 32 is configured to have a predetermined thickness or less.

[0100] As described above, although the present disclosure has been described with reference to limited embodiments and drawings, the present disclosure is not limited thereto, and various modifications and variations are possible within the technical concept of the present disclosure and those skilled in the art to which the present disclosure belongs will be understood to be within the equivalent scope of the claims described below.

[0101] [Explanation of Reference Numerals]

[0102] 1 Ultrasonic welding system

[0103] 3 Ultrasonic welding device

[0104] 5 Welding head

[0105] N Knurled part

[0106] T-tab

[0107] 7 Anvil

[0108] S1 First component

[0109] S2 Second component

[0110] 10 Electrode assembly

[0111] 11 First uncoated portion

[0112] C Center hole

[0113] 30 Collector

[0114] 31 First connection part

[0115] L Laser welding part

[0116] 32 Second connection part

[0117] U Ultrasonic welding part

[0118] 40 terminals

[0119] 41 Terminal exposed part

[0120] 42 terminal insertion part

Claims

1. An ultrasonic welding device, comprising: a welding head configured to press the first member to ultrasonically weld the first member and the second member, wherein the welding head comprises a knurled portion having a plurality of protrusions to produce a non-uniform shape in the first member, the plurality of protrusions being configured to protrude toward the first member, and Wherein, the shape of the protrusion located in the outermost area of ​​the knurled portion is different from the shape of the protrusion located in the inner area of ​​the knurled portion.

2. The ultrasonic welding device according to claim 1, in, The protrusion is configured such that a cross-sectional area of ​​the protrusion gradually decreases toward the first member.

3. The ultrasonic welding device according to claim 1, in, A first width of the protrusion at an end point of the protrusion is smaller than a second width of the protrusion at a point where the protrusion starts to protrude.

4. The ultrasonic welding device according to claim 3, in, The first width of the protrusions in the outermost region of the knurled portion is greater than the first width of the protrusions in the inner region of the knurled portion.

5. The ultrasonic welding device according to claim 3, in, The first width of the protrusion located in the outermost region of the knurled portion is 1.2 to 1.8 times the first width of the protrusion located in the inner region of the knurled portion.

6. The ultrasonic welding device according to claim 3, in, The second width of the protrusion located in the outermost region of the knurled portion is less than or equal to the second width of the protrusion located in the inner region of the knurled portion.

7. The ultrasonic welding device according to claim 3, in, The second width of the protrusion located in the outermost region of the knurled portion is 0.4 to 1.0 times the second width of the protrusion located in the inner region of the knurled portion.

8. The ultrasonic welding device according to claim 1, in, The height of the protrusions located in the outermost region of the knurled portion is smaller than the height of the protrusions located in the inner region of the knurled portion.

9. The ultrasonic welding device according to claim 1, in, The protrusion is configured to have a trapezoidal shape in a longitudinal cross section of the protrusion.

10. A structure comprising a plurality of stacked objects to be welded, in, performing ultrasonic welding on the plurality of stacked objects, wherein a plurality of indentations are formed on the outer surfaces of the plurality of stacked objects by ultrasonic welding, and Among the plurality of indentations, the width of the indentation in the outermost region is greater than the width of the indentation in the inner region.

11. A structure comprising a plurality of stacked objects to be welded, in, performing ultrasonic welding on the plurality of stacked objects, wherein a plurality of indentations are formed on the outer surfaces of the plurality of stacked objects by ultrasonic welding, and Among the plurality of indentations, a depth of an indentation in an outermost region is smaller than a depth of an indentation in an inner region.

12. The structure according to claim 10 or 11, in, The structure including the plurality of stacked objects to be welded is a cylindrical battery.

13. The structure according to claim 12, in, The plurality of stacked objects to be welded are terminals and collectors included in the cylindrical batteries.

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