Welding device

Abstract

The utility model relates to a welding device. The welding device according to an embodiment of the present application may comprise: a welding head having a first welding surface on which a plurality of first protrusions are provided; and an anvil facing the horn, having a plurality of electrode tabs included in a secondary battery between the horn and the anvil, the anvil having a second welding surface on which a plurality of second protrusions are provided, the shape of the plane cross section of each first protrusion is different from that of the plane cross section of each second protrusion, and the width of each electrode connecting piece arranged between the welding head and the anvil block is larger than that of the welding head.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10 - 2022 - 0019798, filed on February 15, 2022, the entire contents of which are incorporated herein by reference. Technical field

[0003] This application relates to a welding device, and more particularly, to a welding device capable of minimizing the occurrence of welding defects. Background art

[0004] The demand for secondary batteries as an energy source for electronic devices such as mobile phones, laptop computers, and wearable devices, or electric vehicles, is increasing. According to the type of electrode, secondary batteries are classified into nickel - cadmium secondary batteries, nickel - metal hydride secondary batteries, lithium secondary batteries, etc., and research and development of lithium secondary batteries, which have advantages such as a high operating voltage and a high energy density per unit weight, are being actively carried out.

[0005] Generally, a secondary battery may include an electrode assembly and a case using the electrode assembly. A plurality of electrodes may be stacked in one electrode assembly, and in order to easily supply the power generated from the plurality of electrodes to the outside, electrode tabs may be provided on each electrode. A welding device including a welding head and an anvil may be used to weld a plurality of electrode tabs to each other through a welding process. However, it may not be possible to appropriately ensure the welding strength during the welding process, or welding defects may occur due to deviations occurring during the manufacturing process, etc. Summary of the utility model

[0006] Technical problem

[0007] According to an embodiment of the present application, there is provided a welding device capable of minimizing the occurrence of welding defects.

[0008] The technical problems of the present application are not limited to the above - mentioned technical problems, and those skilled in the art will clearly understand other technical problems not described herein from the following description.

[0009] Technical solution

[0010] A welding device according to an embodiment of the present application may include: a welding head having a first welding surface on which a plurality of first protrusions are provided; and an anvil facing the welding head, with a plurality of electrode tabs disposed in a secondary battery between the welding head and the anvil, the anvil having a second welding surface on which a plurality of second protrusions are provided, wherein the shape of the planar cross-section of each of the first protrusions is different from the shape of the planar cross-section of each of the second protrusions, and the width of each of the electrode tabs aligned between the welding head and the anvil is greater than the width of the welding head.

[0011] According to an embodiment, the electrode tab may include a starting point and an ending point, the starting point being disposed relatively far from an electrode lead provided in the secondary battery, and the ending point being disposed adjacent to the electrode lead. The first welding surface may include a first region close to the starting point of the electrode tab and a second region far from the starting point of the electrode tab. Each of the first protrusions may be disposed to be spaced apart from an adjacent first protrusion in the first region and not spaced apart from an adjacent first protrusion in the second region.

[0012] According to an embodiment, in the first region, the spacing distance between the plurality of first protrusions may be set to be the same as the pitch of the first protrusions.

[0013] According to an embodiment, at least one of the first protrusions or the second protrusions may have a pitch of 1.2 mm to 1.5 mm.

[0014] According to an embodiment, the width of the welding head may be set to be 2 mm to 2.5 mm smaller than the width of the electrode tab.

[0015] According to an embodiment, the width of the anvil may be greater than or equal to the width of the welding head.

[0016] According to an embodiment, each of the first protrusions and each of the second protrusions may have the shape of a frustum of a square pyramid. The first protrusion may include a first outer surface facing the anvil, the first outer surface having a rectangular shape with a first horizontal length extending in a first direction and a second horizontal length extending in a second direction. The second protrusion may include a second outer surface facing the welding head, the second outer surface being parallel to the first outer surface and having a rhombus shape in which a first diagonal is transverse to the first direction, a second diagonal is transverse to the second direction, and the first diagonal and the second diagonal are perpendicular to each other.

[0017] According to an embodiment, the welding head may include a first side surface, a second side surface, a third side surface, and a fourth side surface, and each of the first side surface, the second side surface, the third side surface, and the fourth side surface contacts the first welding surface to define an edge. The radius of curvature of one of the first side surface, the second side surface, the third side surface, and the fourth side surface may be greater than the radius of curvature of each of the remaining side surfaces of the first side surface, the second side surface, the third side surface, and the fourth side surface.

[0018] According to an embodiment, the first side surface may be disposed near the starting point of the electrode tab, and the radius of curvature of the first side surface may be greater than the radius of curvature of at least one of the second side surface, the third side surface, or the fourth side surface.

[0019] Beneficial effect

[0020] According to an embodiment of the present application, the welding strength can be ensured during ultrasonic welding of the electrode tab.

[0021] In addition, according to an embodiment of the present application, damage to the electrode tab caused by direct contact with the welding head can be minimized, and thus the occurrence of welding defects (e.g., disconnection) can be prevented or reduced.

[0022] In addition, according to an embodiment of the present application, manufacturing process defects can be prevented or reduced, and thus, the performance of the secondary battery can be ensured and the safety of the secondary battery can be improved.

[0023] In addition, various effects directly or indirectly discovered herein can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is an exploded perspective view of a secondary battery according to an embodiment of the present application.

[0025] Figure 2 is a view of a device for manufacturing a secondary battery according to an embodiment of the present application.

[0026] Figure 3 is a plan view of a welding head included in a device for manufacturing a secondary battery according to an embodiment of the present application.

[0027] Figure 4 is a view showing along Figure 3 a cross-sectional view of the welding head taken along line A-A' in

[0028] Figure 5It is a view showing the relationship between the interval between the first protrusions of a welding head included in an apparatus for manufacturing a secondary battery according to an embodiment of the present application and the tensile strength.

[0029] Figure 6 It is a plan view of an anvil included in an apparatus for manufacturing a secondary battery according to an embodiment of the present application.

[0030] Figure 7 It is shown along Figure 6 A cross-sectional view of the anvil taken along line B-B' in

[0031] Figure 8a and 8b It is a view for explaining the width relationship between a welding head and an anvil during the process of manufacturing a secondary battery according to an embodiment of the present application.

[0032] Figure 9a It is a view for explaining the arrangement relationship between a welding head and an electrode tab during the process of manufacturing a secondary battery according to an embodiment of the present application.

[0033] Figure 9b It is a view showing an electrode tab after the manufacturing process according to an embodiment of the present application.

[0034] Figure 9c It is a view showing an electrode tab after the manufacturing process according to a comparative example.

[0035] Figure 10 It is a view showing the relationship between the number of stacked electrode tabs of a secondary battery and the first width of a first welding surface according to an embodiment of the present application.

[0036] Figure 11 It is a plan view of a welding head having a curved surface shape on its side surface according to another embodiment of the present application.

[0037] Figure 12 It is along Figure 11 A cross-sectional view taken along line C-C' in

[0038] Figure 13 It is a plan view of an anvil having a curved surface shape on its side surface according to another embodiment of the present application.

[0039] Figure 14 It is along Figure 13 A cross-sectional view taken along line D-D' in Detailed Description

[0040] Hereinafter, preferred embodiments of the present application will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present application pertains can easily implement the present application. However, the present application can be implemented in different forms and should not be construed as being limited by the embodiments set forth herein.

[0041] To clearly describe the present application, descriptions of irrelevant parts or detailed descriptions of related well-known technologies that may unnecessarily obscure the subject matter of the present application will be excluded. Throughout the specification, the same reference numerals denote the same elements.

[0042] In addition, the terms or words used in this specification and the claims should not be construed restrictively as ordinary meanings or dictionary-based meanings, but should be construed as meanings and concepts that conform to the scope of the present application based on the concept that the inventor can appropriately define the terms to best describe and explain the principles of his or her invention.

[0043] Figure 1 is an exploded perspective view showing a secondary battery according to an embodiment of the present application.

[0044] Refer to Figure 1 , a secondary battery 1 according to an embodiment of the present application may include an electrode assembly 10 and a case 13 surrounding the electrode assembly 10.

[0045] The electrode assembly 10 is a power generation device in which a positive electrode and a negative electrode are sequentially stacked with a separator interposed therebetween, and may have a stacked type or a stacked and folded type structure. The separator included in the electrode assembly 10 insulates the positive electrode and the negative electrode from each other.

[0046] The electrode assembly 10 may include a plurality of electrode tabs 11 extending from the electrode assembly 10. The electrode assembly 10 may include a positive electrode tab 111 and a negative electrode tab 112. The positive electrode tab 111 may extend from the positive electrode of the electrode assembly 10 to protrude outside the electrode assembly 10. The negative electrode tab 112 may extend from the negative electrode of the electrode assembly 10 to protrude outside the electrode assembly 10.

[0047] An electrode lead 12 may be connected to the electrode tab 11. For example, the electrode lead 12 may be connected to the electrode tab 11 through a welding process such as laser welding. The electrode lead 12 may include a positive electrode lead 121 and a negative electrode lead 122. The positive electrode lead 121 and the negative electrode lead 122 may extend in the same direction or in opposite directions according to the formation positions of the positive electrode tab 111 and the negative electrode tab 112. The positive electrode lead 121 and the negative electrode lead 122 may have different materials. For example, the positive electrode lead 121 may have the same aluminum (Al) material as the positive electrode, and the negative electrode lead 122 may have the same copper (Cu) material as the negative electrode or a copper material coated with nickel (Ni). The portion of the electrode lead 12 protruding outside the case 13 may serve as a terminal portion electrically connected to an external terminal.

[0048] The electrode lead 12 may have a portion surrounded by the insulating portion 14. The upper pocket 131 and the lower pocket 132 of the housing 13 are heat-sealed to each other at the sealing portion 134, and the insulating portion 14 may be disposed on the sealing portion 134 to join the electrode lead 12 to the housing 13. In addition, the electric power generated from the electrode assembly 10 can be prevented from flowing to the housing 13 through the electrode lead 12, and the sealing of the housing 13 can be maintained. The insulating portion 14 is made of a non-conductive material that does not allow current to flow smoothly. A material that can be easily attached to the electrode lead 12 and has a relatively small thickness may be used for the insulating portion 14. For example, the insulating portion 14 may be made of an insulating tape. The material of the insulating portion 14 is not limited to the insulating tape, and various members may be used as long as these members can insulate the electrode lead 12.

[0049] The housing 13 provides a receiving space capable of receiving the electrode assembly 10 and has a bag shape as a whole. The housing 13 can receive and seal the electrode assembly 10 such that a portion (i.e., the terminal portion) of the electrode lead 12 is exposed. The housing 13 includes an upper pocket 131 and a lower pocket 132. The lower pocket 132 is provided with a receiving space 133 capable of receiving the electrode assembly 10, and the upper pocket 131 covers the receiving space 133 on the upper side so that the electrode assembly 10 does not come off to the outside of the housing 13. Here, the receiving space 133 may also be defined in the upper pocket 131 to receive the electrode assembly 10 from the upper side. The upper pocket 131 and the lower pocket 132 may be manufactured such that the corresponding sides of the upper pocket 131 and the lower pocket 132 are connected to each other, but the embodiments of the present application are not limited thereto. For example, the upper pocket 131 and the lower pocket 132 may be manufactured in various ways, such as being separately manufactured.

[0050] The electrode tabs 11 included in such a secondary battery may be connected to each other by at least one welding process among resistance welding, laser welding, and ultrasonic welding.

[0051] Figure 2 is a view showing a device for manufacturing a secondary battery according to an embodiment of the present application. Figure 2 The shown manufacturing device may be an ultrasonic welding device that welds the electrode tabs 11 to each other.

[0052] Reference Figure 2 , a device 200 for manufacturing a secondary battery according to an embodiment of the present application may include a welding head 300 and an anvil 400. The welding head 300 may include a plurality of first protrusions 320, and the anvil 400 may include a plurality of second protrusions 420.

[0053] A plurality of electrode tabs 11 as welding targets may be disposed on an anvil 400. The welding head 300 and the anvil 400 may be aligned to face each other, and the plurality of electrode tabs 11 are located between the welding head 300 and the anvil 400. The welding head 300 may press the plurality of electrode tabs 11 with a fixed load while applying ultrasonic waves to the welding head 300 to weld the plurality of electrode tabs 11 to each other.

[0054] When the welding head 300 applies pressure vertically (e.g., in the negative (-) Z direction), the welding head 300 may undergo horizontal vibrations (e.g., in the X direction and / or the Y direction) such that frictional heat is generated on the contact surface between the electrode tabs 11. The electrode tabs 11 may be welded to each other by the generated frictional heat. As an example, the anvil 400 may be fixed while the welding head 300 performs a vertical movement to apply pressure vertically.

[0055] Figure 3 is a plan view showing a welding head included in an apparatus for manufacturing a secondary battery according to an embodiment of the present application. Figure 4 is shown along Figure 3 is a cross-sectional view of the welding head taken along line A-A' in

[0056] Reference Figure 3 and Figure 4 According to an embodiment of the present application, the welding head 30 may include a plurality of first protrusions 320 provided on a first welding surface 310.

[0057] The first welding surface 310 may include a first region 311 and a second region 312. The first region 311 may have a smaller area than the second region 312. The first region 311 may be a peripheral region adjacent to the starting point of the electrode tab (e.g., the electrode tab 11 in Figure 1 ). The starting point of the electrode tab may be a region set relatively far from the electrode lead (e.g., the electrode lead 12 in Figure 1 ), and the ending point of the electrode tab may be a region set adjacent to the electrode lead.

[0058] The plurality of first protrusions 320 may be provided in some regions of the first region 311, and the plurality of first protrusions 320 may not be provided in the remaining regions of the first region 311.

[0059] The plurality of first protrusions 320 may have the same size or different sizes between the first region 311 and the second region 312. For example, the first protrusions 320 provided in the first region 311 and the first protrusions 320 provided in the second region 312 may have the same pitch P1.

[0060] A plurality of first protrusions 320 may be arranged in a row in a first direction (e.g., the X direction) in a first region 311. In the first region 311, each first protrusion 320 may be set to be spaced apart from an adjacent first protrusion 320 by a preset first spacing distance d1 in the first direction. Each first protrusion 320 provided in the first region 311 may not be spaced apart from an adjacent first protrusion 320 in a second direction (e.g., the Y direction), but may be set to be in contact with the adjacent first protrusion 320.

[0061] According to an embodiment, in the first region 311, the first spacing distance d1 by which the first protrusion 320 is spaced apart from an adjacent first protrusion 320 is the same as or similar to the pitch P1 of the first protrusion 320. The pitch P1 of each first protrusion 320 may be 1.2 mm to 1.5 mm. For example, when the pitch P1 of each first protrusion 320 is 1.2 mm, on the first region 311 of the first welding surface 310, each first protrusion 320 may be set to be spaced apart from an adjacent first protrusion 320 by a first spacing distance d1 of 1.2 mm in the first direction.

[0062] On a second region 312 of the first welding surface 310, a plurality of first protrusions 320 may be arranged in a matrix shape in the first and second directions. In the second region 312, each first protrusion 320 may not be spaced apart from an adjacent first protrusion 320 in the first and second directions, but may be set to be in contact with the adjacent first protrusion 320.

[0063] Each first protrusion 320 may include a first inner surface 321 and a first outer surface 322 that are parallel to each other. The first inner surface 321 may be in contact with the first welding surface 301. The first outer surface 322 may be set to be opposite to the first inner surface 321 and face the anvil 400 during the welding process. Each first protrusion 320 may have a size that gradually decreases from the first inner surface 321 to the first outer surface 322. The area of the first outer surface 322 may be smaller than the area of the first inner surface 321. The area of the first outer surface 322 may be set to an area such that the first outer surface 322 is embedded in the electrode tab to ensure a minimum welding force and also minimize damage to the electrode tab.

[0064] The planar cross-section of each of the first protrusions 320 may have a polygonal shape. As an example, each of the first outer surface 322 and the first inner surface 321 may have a rectangular shape having a horizontal length parallel to the first direction and a vertical length parallel to the second direction (or the vibration direction). Each of the first protrusions 320 may have the shape of a frustum of a square pyramid. For example, the first outer surface 322 of each of the first protrusions 320 may be arranged to have a square shape with two sides parallel to the vibration direction. Compared with a comparative example in which the first outer surface of the first protrusion has a rhombus shape, an embodiment in which the first outer surface 322 of each of the first protrusions 320 has a square shape may have a lower maximum plastic strain and a higher tensile strength of the electrode tab. Therefore, according to an embodiment of the present application, disconnection of the electrode tab during the welding process can be prevented.

[0065] Figure 5 is a view showing the relationship between the interval between the first protrusions of the welding head included in the apparatus for manufacturing a secondary battery according to an embodiment of the present application and the tensile strength.

[0066] Reference Figure 5 , as the first interval distance d1 between the first protrusions (e.g., the first protrusions 320 in Figure 3 and Figure 4 the first region 311) provided in the first region (e.g., Figure 3 and Figure 4 ) increases, the stress propagation distance (or non-welded region) between adjacent welded portions can increase. Therefore, the elongation at break can increase and the tensile strength can increase. As the tensile strength of the outermost electrode tab (e.g., the electrode tab 11 in Figure 1 ) increases, disconnection of the electrode tab can be prevented. For example, when the distance between the first protrusions is 1.0 mm, the tensile strength can increase by 15% compared to a distance of 0 mm.

[0067] Figure 6 is a plan view of an anvil included in the apparatus for manufacturing a secondary battery according to an embodiment of the present application. Figure 7 is a cross-sectional view of the anvil taken along the line B-B' in Figure 6 .

[0068] Reference Figure 6 and Figure 7 , the anvil 400 according to an embodiment of the present application may include a plurality of second protrusions 420 provided on the second welding surface 410.

[0069] A plurality of second protrusions 420 may be arranged on the second welding surface 410 in a matrix shape in a first direction (e.g., the X direction) and a second direction (e.g., the Y direction). The plurality of second protrusions 420 may have the same size or different sizes. Each second protrusion 420 may be set to have a pitch P2 of 1.2 mm to 1.5 mm.

[0070] Each second protrusion 420 may include a second inner surface 421 and a second outer surface 422 that are parallel to each other. The second inner surface 421 may be in contact with the second welding surface 410. The second outer surface 422 may be set to be opposite to the second inner surface 421 and face the welding head (e.g., Figure 2 the welding head 300 in). Each second protrusion 420 may have a size that gradually decreases from the second inner surface 421 to the second outer surface 421. The area of the second outer surface 422 may be smaller than the area of the second inner surface 421. The area of the second outer surface 422 may be set to an area in which the second outer surface 422 is embedded in the electrode tab (e.g., Figure 2 the electrode tab 11 in) to ensure a minimum welding force and also minimize damage to the electrode tab.

[0071] The shape of the planar cross-section of each second protrusion 420 may be different from the shape of the planar cross-section of each first protrusion (e.g., Figure 3 and Figure 4 the first protrusion 320 in). As an example, the planar cross-section of each second protrusion 420 may have a rhombus shape. At least one of the second outer surface 422 or the second inner surface 421 may have a rhombus shape in which a first diagonal parallel to the first direction and a second diagonal parallel to the second direction are perpendicular to each other. Each first protrusion 320 may have a frustum of a quadrangular pyramid in which the second outer surface and the second inner surface each have a rhombus shape. The second diagonal included in each of the second outer surface 422 and the second inner surface 421 may be parallel to the vibration direction of the welding head.

[0072] The second inner surface 421 of each second protrusion 420 may not be spaced apart from an adjacent second inner surface 421 by a certain distance in the first direction and the second direction, but may be set to be in contact with the adjacent second inner surface 421.

[0073] According to the direction in which the second outer surfaces 422 are adjacent to each other, the corresponding second outer surfaces 422 of the plurality of second protrusions 420 may have different spacing distances. The second outer surface 422 of each second protrusion 420 may be spaced apart from an adjacent second outer surface 422 by a second spacing distance d2 in a first direction. The second outer surface 422 of each second protrusion 420 may be spaced apart from an adjacent second outer surface 422 by a second spacing distance d2 in a second direction. The second outer surface 422 of each second protrusion 420 may be spaced apart from an adjacent second outer surface 422 by a third spacing distance d3 in a direction parallel to one side edge of the second outer surface 422. The second outer surface 422 of each second protrusion 420 may be spaced apart from an adjacent second outer surface 422 by a third spacing distance d3 in a direction parallel to the other side edge of the second outer surface 422. Since the second outer surfaces 422 of the plurality of second protrusions 420 are spaced apart by different distances according to the direction in which the second outer surfaces 422 are adjacent to each other, and the third spacing distance d3 is smaller than the second spacing distance d2, the welding deviation is small.

[0074] Figure 8a and 8b are views for explaining the width relationship between the welding head and the anvil during the manufacturing process of a secondary battery according to an embodiment of the present application.

[0075] Reference Figure 8a and 8b , according to an embodiment of the present application, during the manufacturing process of a secondary battery, the welding head 300 and the anvil 400 may be aligned to face each other. The first welding surface 310 of the welding head 300 and the second welding surface 410 of the anvil 400 may be arranged to face each other. The first protrusions (e.g., Figure 3 and Figure 4 the first protrusion 320 in) may be provided on the first welding surface 310, and the second protrusions 420 may be provided on the second welding surface 410.

[0076] The size of the second welding surface 410 may be greater than or equal to the size of the first welding surface 310. For example, the second width W2 of the second welding surface 410 may be greater than or equal to the first width W1 of the first welding surface 310. When the second welding surface 410 of the anvil 400 is set to be greater than or equal to the first welding surface 310 of the welding head 300, the area of the electrode tab (e.g., Figure 2 the electrode tab 11 in) that contacts (or is pressed by the first welding surface 310 of the welding head 300) may be set as the welding area. It is possible to prevent the occurrence of a non-welding area in the area of the electrode tab pressed by the welding head 300.

[0077] Figure 9ais a view for explaining the arrangement relationship between a welding head and an electrode tab during the process of manufacturing a secondary battery according to an embodiment of the present application, Figure 9b is a view showing the electrode tab after the manufacturing process according to an embodiment of the present application, Figure 9c is a view showing the electrode tab after the manufacturing process according to a comparative example. Figures 9a to 9c The electrode tab 11 shown may be an electrode tab extending from a stacked or stacked and folded electrode assembly.

[0078] Reference Figure 9a , according to an embodiment of the present application, during the process of manufacturing a secondary battery, the electrode tab 11 may be aligned with the welding head 300. The welding head 300 having a first width W1 of the first welding surface 310 and the electrode tab 11 having a third width W3 may be aligned for a welding process. The first width W1 may be smaller than the third width W3. For example, the first width W1 of the welding head 300 may be set to be 2 mm to 2.5 mm smaller than the third width W3 of the electrode tab 11.

[0079] Some regions of the electrode tab 11 aligned with the welding head 300 may not overlap with the first protrusion (e.g., Figure 4 the first protrusion 320 in) of the welding head 300, and the remaining regions of the electrode tab 11 may not overlap with the welding head 300. The central region 113 of the electrode tab 11 may overlap with the first protrusion of the welding head 300, and the peripheral regions 111 and 112 of the electrode tab 11 may not overlap with the first protrusion of the welding head 300. The peripheral regions 111 and 112 of the electrode tab 11 may extend from some parts of the central region 113 of the electrode tab 11 to face each other. For example, the peripheral regions of the electrode tab 11 may include a first peripheral region 111 and a second peripheral region 112. The first peripheral region 111 and the second peripheral region 112 may be set to be spaced apart from each other in the width direction of the electrode tab 11.

[0080] The first peripheral region 111 of the electrode tab 11 may be aligned to protrude a first extension width We1 from one side of the welding head 300. The second peripheral region 112 of the electrode tab 11 may be aligned to protrude a second extension width We2 from the other side of the welding head 300. The first extension width We1 and the second extension width We2 may have the same size or different sizes. For example, the first extension width We1 and the second extension width We2 may have the same size of 1 mm to 1.25 mm.

[0081] After a welding process using a soldering head 300 aligned with the electrode tab 11, the central region 113 of the electrode tab 11 can be set as a welding region, and the first peripheral region 111 and the second peripheral region 112 of the electrode tab 11 can be set as non-welding regions. Even if there are meandering lines in the foil forming the electrode tab 11, since the width of the soldering head 300 is smaller than the width of the electrode tab 11, the peripheral regions 111 and 112 of the electrode tab 11 can be set as non-welding regions. Therefore, it is possible to prevent the peripheral regions 111 and 112 of the electrode tab 11 from being pressed during the welding process, and thus, it is possible to increase the tensile strength of the peripheral regions 111 and 112 of the electrode tab 11.

[0082] Specifically, as Figure 9b shown, in the electrode tab 11 according to the embodiment, after a welding process using a soldering head 300 with a width smaller than the width of the electrode tab 11, the first peripheral region 111 and the second peripheral region 112 can be set as non-welding regions, and the central region 113 can be set as a welding region. Since the peripheral regions 111 and 112 of the electrode tab 11 are not pressed by the soldering head 300 during the welding process, it is possible to prevent damage to the foil forming the peripheral regions 111 and 112 of the electrode tab.

[0083] On the other hand, as Figure 9c shown, in the electrode tab 11 according to the comparative example, after a welding process using a soldering head 300 with a width larger than the width of the electrode tab 11, the first peripheral region 111, the second peripheral region 112, and the central region 113 can all be set as welding regions. When the peripheral regions 111 and 112 of the electrode tab 11 are pressed by the soldering head 300 during the welding process, the foil forming the peripheral regions 111 and 112 may be damaged.

[0084] For example, as shown in Table 1, it can be seen that the embodiment in which the soldering head 300 is 2 mm smaller than the electrode tab 11 has a tensile strength approximately 8% higher than that of the comparative example in which the width of the soldering head is 3 mm larger than the width of the electrode tab.

[0085] [Table 1]

[0086] Example Control example Tensile strength (kgf) 9.02 8.38

[0087] Therefore, in the embodiment according to the present application, as the tensile strength of the peripheral regions 111 and 112 of the electrode tab 11 relatively increases, the risk of the electrode tab 11 breaking can be reduced. Figure 10 is a view for explaining the relationship between the number of electrode tabs stacked in a secondary battery according to an embodiment of the present application and the first width of the first welding surface. Referring to Figure 10 , as the stacked electrode tabs (e.g., Figure 9aThe number of electrode tabs 11) therein is increased, and the first welding surface of the welding head (e.g., Figure 3 and Figure 4 the first welding surface 310 of the welding head 300 therein) (e.g., Figure 3 and Figure 4 the first width of the first welding surface 310 (e.g., Figure 9a the first width W1 therein) can be reduced. Additionally, as the thickness of the electrode tab increases, the pitch of at least one of the first protrusions or anvils of the welding head (e.g., Figure 6 and Figure 7 the anvil 400 therein) (e.g., Figure 6 and Figure 7 the second protrusion 420 therein) can be increased. The thickness of the electrode tab can be calculated by multiplying the number of stacked electrode tabs by the thickness of one sheet of foil. Welding heads and anvils including protrusions with different pitches can be used to weld electrode tabs with a predetermined thickness to each other through a welding process. For example, a welding head including a first protrusion with a first pitch (e.g., Figure 3 the first pitch P1 therein) and an anvil including a second protrusion with a second pitch smaller than the first pitch (e.g., Figure 6 the second pitch P2 therein) can be used to weld electrode tabs with a predetermined thickness to each other through a welding process. Welding heads and anvils including protrusions with the same or different pitches can be used to weld negative electrode tabs and positive electrode tabs with the same thickness through a welding process. For example, when the positive electrode tab and the negative electrode tab have the same thickness, the welding head and anvil applied to the negative electrode tab can have the same or a greater pitch than the pitch of the welding head and anvil applied to the positive electrode tab.

[0088] Figure 11 FIG. is a plan view showing a welding head having a curved surface shape on a side surface according to another embodiment of the present application. Figure 12 FIG. is a cross-sectional view taken along line C-C' in Figure 11 FIG.

[0089] Referring to Figure 11 and Figure 12 , the first welding surface 310 of the welding head according to another embodiment of the present application may include a first region 311, a second region 312, and a third region 313. The description of the first region 311 and the second region 312 of the first welding surface 310 described with reference to Figure 3 and Figure 4 is applicable to the first region 311 and the second region 312 of the first welding surface 310 shown in Figure 11 and Figure 12 , and thus, the repeated description will be omitted.

[0090] The third region 313 of the first welding surface 310 may be set to surround a part of the first region 311 and a part of the second region 312. The third region 313 of the first welding surface 310 may contact the first side surface 1111, the second side surface 1112, the third side surface 1113, and the fourth side surface 1114 of the welding head 300 to define an edge. The first side surface 1111 may extend in a first direction (e.g., the X direction), and is set to be close to the starting point of the electrode tab (e.g., Figure 2 the electrode tab 11 in

[0091] during the welding process. The second side surface 1112 may be set to face the first side surface 1111, and is set to be away from the starting point of the electrode tab during the welding process. The third side surface 1113 may extend in a second direction and is disposed between the first side surface 1111 and the second side surface 1112. The fourth side surface 1114 may be set to face the third side surface 1113.

[0092] To define the edge of the welding head to have a curved surface shape, at least one of the first side surface 1111, the second side surface 1112, the third side surface 1113, or the fourth side surface 1114 may be set to have a curved surface shape by a processing treatment (e.g., chamfering). The second side surface 1112, the third side surface 1113, the first side surface 1111, and the fourth side surface 1114 may be processed in sequence.

[0093] According to an embodiment, the side surface among the first side surface 1111, the second side surface 1112, the third side surface 1113, and the fourth side surface 1114 that is set to be close to the starting point of the electrode tab during the welding process may have a larger radius of curvature than the other side surfaces. The radius of curvature of the first side surface 1111 may be set to be greater than the radius of curvature of at least one of the second side surface 1112, the third side surface 1113, or the fourth side surface 1114. For example, the respective radii of curvature of the second side surface 1112, the third side surface 1113, and the fourth side surface 1114 may be set to be the same, and the radius of curvature of the first side surface 1111 may be set to be greater than the radii of curvature of the second side surface 1112, the third side surface 1113, and the fourth side surface 1114.

[0094] According to an embodiment, side surfaces of each outermost first protrusion 320 adjacent to the first side surface 1111, the second side surface 1112, the third side surface 1113, and the fourth side surface 1114, respectively, may also have a circular shape during a processing operation. In this case, a radius of curvature of each outermost first protrusion 320 adjacent to the first side surface 1111 may be greater than a radius of curvature of each outermost first protrusion 320 adjacent to the second side surface 1112, the third side surface 1113, and the fourth side surface 1114, respectively.

[0095] Figure 13 is a plan view of an anvil having a curved surface shape on a side surface according to another embodiment of the present application. Figure 14 is along Figure 13 in the line D-D' of the cross-sectional view. Refer to Figure 6 and Figure 7 The description of the anvil described can be applied to Figure 13 and Figure 14 The anvil shown, and thus, repeated descriptions will be omitted.

[0096] Refer to Figure 13 and Figure 14 , an anvil 400 according to an embodiment of the present application may include one side surface 1311 and another side surface 1312 facing each other. One side surface 1311 and another side surface 1312 of the anvil 400 may contact a second welding surface 410 to define an edge. An edge defined by the second welding surface 410 contacting one side surface 1311 and another side surface 1312, respectively, may be provided to have a gentle curved surface. The edge having a curved surface shape defined on the anvil 400 may disperse pressure applied to an electrode tab (e.g., Figure 1 the electrode tab 11 in

[0097] ), and thus, damage to the electrode tab may be prevented.

[0098] According to an embodiment, the side surfaces of each outermost second protrusion 420 adjacent to one side surface 1311 and another side surface 1312 may also have a circular shape during the processing. In this case, the radius of curvature of each outermost second protrusion 420 adjacent to one side surface 1311 may be the same as the radius of curvature of each outermost second protrusion 420 adjacent to another side surface 1312.

[0099] Although the present application has been described with reference to limited embodiments and drawings, the present application is not limited thereto, and those of ordinary skill in the art to which the present application pertains can implement the present application in various ways within the technical concept of the present application and equivalent solutions of the appended claims.

[0100] [Description of Reference Numerals]

[0101] 1: Secondary battery

[0102] 10: Electrode assembly

[0103] 11: Electrode tab

[0104] 200: Welding device

[0105] 300: Welding head

[0106] 320, 420: Protrusion

[0107] 400: Anvil

Claims

1. A welding device, characterized in that, the welding device comprises: a welding head having a first welding surface on which a plurality of first protrusions are provided; and an anvil facing the welding head, with a plurality of electrode tabs disposed in a secondary battery between the welding head and the anvil, the anvil having a second welding surface on which a plurality of second protrusions are provided, wherein the shape of the planar cross-section of each of the first protrusions is different from the shape of the planar cross-section of each of the second protrusions, wherein the width of each of the electrode tabs aligned between the welding head and the anvil is greater than the width of the welding head.

2. The welding device according to claim 1, characterized in that, each of the electrode tabs comprises: a starting point which is arranged relatively far from the electrode lead disposed in the secondary battery; and an end point which is arranged adjacent to the electrode lead, wherein the first welding surface comprises: a first region near the starting point of the electrode tab; and a second region far from the starting point of the electrode tab, wherein each of the first protrusions is arranged to be spaced apart from each adjacent first protrusion on the first region, and wherein each of the first protrusions has no spacing from adjacent first protrusions on the second region.

3. The welding device according to claim 2, characterized in that, in the first region, the spacing distance between the plurality of first protrusions is set to be the same as the pitch of the plurality of first protrusions.

4. The welding device according to claim 1, characterized in that, at least one of the first protrusions or the second protrusions has a pitch of 1.2 mm to 1.5 mm.

5. The welding device according to claim 1, characterized in that, the width of the welding head is set to be 2 mm to 2.5 mm smaller than the width of the plurality of electrode tabs.

6. The welding device according to claim 1, characterized in that, the width of the anvil is greater than or equal to the width of the welding head.

7. The welding device according to claim 1, characterized in that, each of the first protrusions and each of the second protrusions has the shape of a frustum of a square pyramid, the first protrusion comprises a first outer surface facing the anvil, the first outer surface having a rectangular shape with a first horizontal length extending in a first direction and a second horizontal length extending in a second direction, the second protrusion comprises a second outer surface facing the welding head, the second outer surface being parallel to the first outer surface and having a rhombus shape, in the rhombus shape, a first diagonal is transverse to the first direction, a second diagonal is transverse to the second direction, and the first diagonal and the second diagonal are perpendicular to each other.

8. The welding device according to claim 2, characterized in that, The welding head includes a first side surface, a second side surface, a third side surface, and a fourth side surface, and each of the first side surface, the second side surface, the third side surface, and the fourth side surface contacts the first welding surface to define an edge. The radius of curvature of one of the first side surface, the second side surface, the third side surface, and the fourth side surface is greater than the radius of curvature of each of the remaining side surfaces of the first side surface, the second side surface, the third side surface, and the fourth side surface.

9. The welding device according to claim 8, wherein, the first side surface is arranged to be close to the starting point of the plurality of electrode tabs, and the radius of curvature of the first side surface is greater than the radius of curvature of at least one of the second side surface, the third side surface, or the fourth side surface.

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