Ultrasonic Welding Device and Ultrasonic Welding Method for Secondary Battery

Abstract

The ultrasonic welding device for a secondary battery according to the present invention is configured to weld the overlapping surface of an electrode tab and an electrode lead provided in an electrode assembly. The ultrasonic welding device includes: an anvil on which the overlapping surface of the electrode tab and the electrode lead is provided; a sonotrode configured to apply ultrasonic waves to the overlapping surface of the electrode tab and the electrode lead provided on the anvil while pressing the overlapping surface; an electrode tab measurement unit configured to measure the thickness of the electrode tab provided on the overlapping surface; and a pressure adjustment device configured to adjust the pressure applied to the overlapping surface by the anvil and the sonotrode according to the thickness value of the electrode tab measured by the electrode tab measurement unit.

Description

[0001] Cross-reference to related applications

[0002] This application claims the priority benefit of Korean Patent Application No. 10-2020-0089914, filed on Jul. 20, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to an ultrasonic welding apparatus and an ultrasonic welding method for secondary batteries, and more particularly, to an ultrasonic welding apparatus and an ultrasonic welding method for secondary batteries that can adjust the pressing force of an anvil and a sonotrode. Background Art

[0004] Generally, unlike non-rechargeable primary batteries, a secondary battery is a rechargeable and dischargeable battery. Such secondary batteries are widely used in high-tech electronic fields such as mobile phones, laptop computers, and portable video cameras.

[0005] Such secondary batteries are classified into can-type secondary batteries in which an electrode assembly is built into a metal can and pouch-type secondary batteries in which an electrode assembly is built into a pouch. The pouch-type secondary battery includes: an electrode assembly provided with an electrode tab, an electrode lead wire coupled to the electrode tab, and a pouch that houses the electrode assembly in a state where the front end of the electrode lead wire is led to the outside.

[0006] Here, the electrode tab and the electrode lead wire are joined to each other using an ultrasonic welding apparatus for secondary batteries. That is, an ultrasonic welding apparatus for secondary batteries according to the related art includes: an anvil on which an overlapping surface of the electrode tab and the electrode lead wire is disposed; and a sonotrode that applies ultrasonic waves to the overlapping surface disposed on the anvil to weld the overlapping surface.

[0007] However, in the ultrasonic welding apparatus for secondary batteries according to the related art, when the overlapping surface is pressed by the anvil and the sonotrode with a pressure exceeding a set pressure, the overlapping surface is deformed, thereby causing product defects. In particular, welding defects are caused due to the deformation of the overlapping surface. Summary of the Invention

[0008] Technical Problem

[0009] In order to solve the above problems, an ultrasonic welding apparatus and an ultrasonic welding method for secondary batteries according to the present invention can adjust the pressing force of an anvil and a sonotrode that press an overlapping surface of an electrode tab and an electrode lead wire, so that the overlapping surface is pressed with a constant pressure by the anvil and the sonotrode, thereby preventing deformation of the overlapping surface, and thus preventing product defects and welding defects from occurring.

[0010] Technical Solution

[0011] To achieve the above object, an ultrasonic welding device for a secondary battery according to the present invention is configured to weld an overlapping surface of an electrode tab and an electrode lead provided in an electrode assembly. The ultrasonic welding device includes: an anvil, on which the overlapping surface of the electrode tab and the electrode lead is provided; a welding head configured to apply ultrasonic waves to the overlapping surface of the electrode tab and the electrode lead provided on the anvil while pressing the overlapping surface; an electrode tab measuring unit configured to measure the thickness of the electrode tab provided on the overlapping surface; and a pressure adjusting device configured to adjust the pressure applied to the overlapping surface by the anvil and the welding head according to the thickness value of the electrode tab measured by the electrode tab measuring unit.

[0012] The pressure adjusting device may include a welding head pressure adjusting unit configured to increase or decrease the pressing force applied by the welding head to the overlapping surface according to the thickness value of the electrode tab measured by the electrode tab measuring unit, thereby adjusting the pressure applied to the overlapping surface by the anvil and the welding head.

[0013] The welding head pressure adjusting unit may include: a welding head control member configured to calculate the pressure value of the welding head by comparing the thickness value measured by the electrode tab measuring unit with a preset thickness reference value of the electrode tab; and a welding head pressure adjusting member configured to increase or decrease the pressing force applied by the welding head to the overlapping surface according to the pressure value of the welding head calculated by the welding head control member.

[0014] The welding head pressure adjusting member may be configured to raise or lower the welding head in the direction of the overlapping surface, thereby adjusting the pressure of the welding head by the distance between the overlapping surface and the welding head.

[0015] Three or more electrode tab measuring units may be installed at the electrode tab provided on the overlapping surface to measure the thicknesses at three or more positions of the electrode tab, and the welding head control member may be configured to set the average value of the three or more thickness values of the electrode tab measured by the electrode tab measuring unit as the thickness value of the electrode tab.

[0016] The ultrasonic welding device may further include an electrode lead measuring unit configured to measure the thickness of the electrode lead provided on the overlapping surface, wherein the welding head pressure adjusting unit may be configured to increase or decrease the pressing force applied by the welding head to the overlapping surface according to the thickness value of the electrode lead measured by the electrode lead measuring unit, thereby adjusting again the pressure applied to the overlapping surface by the anvil and the welding head.

[0017] The pressure regulating device may include an anvil pressure regulating part configured to increase or decrease the pressing force applied by the anvil to the overlapping surface according to the thickness value of the electrode tab measured by the electrode tab measuring part, so as to regulate the pressure applied by the anvil and the welding head to the overlapping surface.

[0018] The anvil pressure regulating part may include: an anvil control member configured to calculate the pressure value of the anvil by comparing the thickness value measured by the electrode tab measuring part with a preset thickness reference value of the electrode tab; and an anvil pressure regulating member configured to increase or decrease the pressing force applied by the anvil to the overlapping surface according to the pressure value of the anvil calculated by the anvil control member.

[0019] The anvil pressure regulating member may be configured to raise or lower the anvil in the direction of the overlapping surface, so as to regulate the pressure of the anvil by adjusting the distance between the overlapping surface and the anvil.

[0020] The ultrasonic welding device may further include a height regulating part configured to constantly maintain the height of the overlapping surface provided between the anvil and the welding head.

[0021] The ultrasonic welding device may further include an arranging member arranged in a state where the electrode tab and the electrode lead provided in the electrode assembly overlap each other.

[0022] According to the ultrasonic welding method for secondary batteries of the present invention, the ultrasonic welding method is performed to weld the overlapping surface of the electrode tab and the electrode lead provided in the electrode assembly. The ultrasonic welding method includes: a setting step of setting the overlapping surface of the electrode tab and the electrode lead provided in the electrode assembly between the welding head and the anvil and setting the overlapping surface on the top surface of the anvil; an electrode tab measuring step of measuring the thickness of the electrode tab provided on the overlapping surface; a pressure regulating step of regulating the pressure applied by the anvil and the welding head to the overlapping surface according to the thickness value of the electrode tab measured in the electrode tab measuring step; and a welding step of applying ultrasonic waves to the overlapping surface while pressing the overlapping surface by the welding head and the anvil whose pressure has been regulated.

[0023] In the pressure regulating step, the pressing force applied by the welding head to the overlapping surface may be increased or decreased according to the thickness value of the electrode tab measured in the electrode tab measuring step, so as to regulate the pressure applied by the anvil and the welding head to the overlapping surface.

[0024] In the pressure adjustment process, the pressing force applied by the anvil to the overlapping surface can be increased or decreased according to the thickness value of the electrode tab measured in the electrode tab measurement process, so as to adjust the pressure applied to the overlapping surface by the anvil and the welding head.

[0025] The ultrasonic welding method may further include a height adjustment process between the setting process and the electrode tab measurement process, and the height adjustment process adjusts the height of the overlapping surface to be constantly maintained.

[0026] Advantageous Effects

[0027] The ultrasonic welding device for secondary batteries according to the present invention may include an anvil, a welding head, an electrode tab measurement unit, and a pressure adjustment device. Therefore, the pressure applied to the overlapping surface by the anvil and the welding head can be constantly adjusted according to the thickness value of the electrode tab, so that the overlapping surface can be welded evenly to prevent damage and deformation of the overlapping surface.

[0028] In addition, in the ultrasonic welding device for secondary batteries according to the present invention, the pressure adjustment device may be configured to adjust the pressure applied to the overlapping surface through the anvil and the welding head by increasing or decreasing the pressing force of the welding head, so as to easily adjust the pressure applied to the overlapping surface.

[0029] In addition, the ultrasonic welding device for secondary batteries according to the present invention may further include an electrode lead measurement unit that measures the thickness of the electrode lead provided on the overlapping surface. Therefore, in addition to the thickness of the electrode lead, the pressure applied to the overlapping surface by the anvil and the welding head can be adjusted again, so as to more precisely adjust the pressure applied to the overlapping surface by the anvil and the welding head.

[0030] In the ultrasonic welding device for secondary batteries according to the present invention, the pressure adjustment device may include an anvil pressure adjustment unit that increases or decreases the pressing force applied by the anvil to the overlapping surface according to the thickness value of the electrode tab, so as to evenly adjust the pressure applied to the overlapping surface by the anvil and the welding head.

[0031] In addition, in the ultrasonic welding device for secondary batteries according to the present invention, the pressure adjustment device may further include a height adjustment unit that maintains a constant height of the overlapping surface provided between the anvil and the welding head, so as to evenly adjust the pressure applied to the overlapping surface by the anvil and the welding head. Brief Description of the Drawings

[0032] Figure 1 is a schematic side view illustrating an ultrasonic welding device for secondary batteries according to a first embodiment of the present invention.

[0033] Figure 2It is a flowchart illustrating an ultrasonic welding method for a secondary battery according to a first embodiment of the present invention.

[0034] Figure 3 It is a schematic side view illustrating an ultrasonic welding apparatus for a secondary battery according to a second embodiment of the present invention.

[0035] Figure 4 It is a graph illustrating the results obtained by measuring the tensile strength of a negative tab and a negative lead wire welded by an ultrasonic welding apparatus for a secondary battery according to a first embodiment of the present invention.

[0036] Figure 5 It is a graph illustrating the results obtained by measuring the tensile strength of a positive tab and a positive lead wire welded by an ultrasonic welding apparatus for a secondary battery according to a first embodiment of the present invention. Detailed Embodiments

[0037] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in such a manner that those of ordinary skill in the art to which the present invention pertains can easily implement the technical concept of the present invention. However, the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. In the drawings, for clarity, any unnecessary content for describing the present invention will be omitted, and in addition, the same reference numerals in the drawings denote the same elements.

[0038] [Secondary Battery According to a First Embodiment of the Present Invention]

[0039] Referring to Figure 1 , a secondary battery according to a first embodiment of the present invention includes an electrode assembly 10 provided with an electrode tab 11 and an electrode lead 20 coupled to the electrode tab 11.

[0040] Here, the electrode tab 11 and the electrode lead 20 are arranged to partially overlap each other, and then the overlapping surface 30 of the electrode tab 11 and the electrode lead 20 is ultrasonically welded by ultrasonic waves to couple the electrode tab 11 to the electrode lead 20. Here, an ultrasonic welding apparatus for a secondary battery according to a first embodiment of the present invention is used.

[0041] [Ultrasonic Welding Apparatus for a Secondary Battery According to a First Embodiment of the Present Invention]

[0042] As shown in Figure 1 , an ultrasonic welding apparatus 100 for a secondary battery according to a first embodiment of the present invention includes: an anvil 110 on which an overlapping surface 30 of an electrode tab 11 and an electrode lead 20 provided in the electrode assembly 10 is disposed; and a welding head 120 that welds the overlapping surface 30 of the electrode tab 11 and the electrode lead 20 disposed on the anvil 110.

[0043] Anvil

[0044] The anvil 110 is disposed below the overlapping surface 30, and the overlapping surface 30 is arranged such that the overlapping surface 30 is in close contact with the top surface of the anvil 110. In addition, a plurality of concavo-convex portions in the shape of triangular pyramids can be formed on the top surface of the anvil 110, and the weldability of the overlapping surface 30 can be improved through the concavo-convex portions.

[0045] The welding head 120 is disposed above the overlapping surface 30 to irradiate ultrasonic waves in a state where the overlapping surface 30 is pressed together with the anvil 110, thereby welding the overlapping surface 30. In addition, a plurality of concavo-convex portions in the shape of triangular pyramids can be formed on the bottom surface of the welding head 120, and the weldability of the overlapping surface 30 can be improved through the concavo-convex portions.

[0046] In the ultrasonic welding device 100 for secondary batteries having the above structure according to the first embodiment of the present invention, in a state where the anvil 110 and the welding head 120 press the overlapping surface 30 of the electrode tab 11 and the electrode lead 20, the overlapping surface 30 can be ultrasonically welded through the welding head 120, thereby bonding the electrode tab 11 to the electrode lead 20.

[0047] In the ultrasonic welding device 100 for secondary batteries according to the first embodiment of the present invention, when the pressure applied to the overlapping surface 30 by the anvil 110 and the welding head 120 is equal to or greater than a set value, the overlapping surface 30 will be stretched, causing damage and deformation, thereby causing welding defects.

[0048] To solve this problem, the ultrasonic welding device 100 for secondary batteries according to the first embodiment of the present invention can keep the pressing force applied to the overlapping surface 30 by the anvil 110 and the welding head 120 constant, thereby preventing the overlapping surface from being damaged and deformed and also preventing welding defects.

[0049] That is to say, the ultrasonic welding device 100 for secondary batteries according to the first embodiment of the present invention can adjust the distance between the anvil 110 and the welding head 120 pressing the overlapping surface 30 to adjust the pressing force applied to the overlapping surface 30 by the anvil 110 and the welding head 120, thereby preventing welding defects of the overlapping surface 30. That is to say, the welding head 120 or the anvil 110 pressing the overlapping surface 30 can be adjusted in height to adjust the pressing force applied to the overlapping surface 30 by the anvil 110 and the welding head 120.

[0050] For example, the ultrasonic welding device 100 for secondary batteries according to the first embodiment of the present invention includes an electrode tab measurement unit 130 and a pressure adjustment device 140.

[0051] Electrode tab measuring section

[0052] The electrode tab measuring unit 130 is provided on one side of the overlapping surface 30 to measure the thickness of the electrode tab 11 provided on the overlapping surface 30.

[0053] Here, three or more electrode tab measuring units 130 are installed at the electrode tab 11 provided on the overlapping surface 30 (at both ends and the center in the length direction of the electrode tab) to measure the thickness at three or more positions of the electrode tab 11.

[0054] Pressure regulating device

[0055] The pressure adjusting device 140 adjusts the pressure applied to the overlapping surface 30 by the anvil 110 and the welding head 120 according to the thickness value of the electrode tab 11 measured by the electrode tab measuring unit 130.

[0056] For example, the pressure adjusting device 140 includes a welding head pressure adjusting unit 141. The welding head pressure adjusting unit 141 increases or decreases the pressing force applied by the welding head 120 to the overlapping surface 30 according to the thickness value of the electrode tab 11 measured by the electrode tab measuring unit 130, thereby adjusting the pressure applied to the overlapping surface 30 by the anvil 110 and the welding head 120.

[0057] The welding head pressure adjusting unit 141 includes: a welding head control member 141a that calculates the pressure value of the welding head 120 by comparing the thickness value measured by the electrode tab measuring unit 130 with a preset thickness reference value of the electrode tab 11; and a welding head pressure adjusting member 141b that increases or decreases the pressing force applied by the welding head 120 to the overlapping surface 30 according to the pressure value of the welding head 120 calculated by the welding head control member 141a.

[0058] The welding head control member 141a can set the average value of three or more thickness values of the electrode tab 11 measured by the electrode tab measuring unit 130 as the thickness value of the electrode tab 11, so that the overall thickness of the electrode tab 11 can be more clearly reflected.

[0059] In addition, the welding head pressure adjusting member 141b can raise or lower the welding head 120 in the direction of the overlapping surface 30 in a state where the distance between the overlapping surface 30 and the welding head 120 is set, so as to reset the distance between the overlapping surface 30 and the welding head 120, thereby adjusting the pressure of the welding head 120 through the distance between the overlapping surface 30 and the welding head 120.

[0060] The welding head pressure adjustment unit 141 with the above structure can calculate the pressure value of the welding head according to the thickness of the electrode tab 11 through the welding head control member 141a, and can also make the welding head 120 rise or fall relative to the overlapping surface 30 through the welding head pressure adjustment member 141b corresponding to the pressure value of the welding head calculated by the welding head control member 141a, thereby adjusting the distance between the overlapping surface 30 and the welding head 120, and as a result, adjusting the pressure exerted by the welding head 120 on the overlapping surface 30.

[0061] Therefore, the ultrasonic welding device 100 for secondary batteries according to the first embodiment of the present invention may include a pressure adjustment device 140 provided with a welding head pressure adjustment unit 141, so that the pressing force exerted on the overlapping surface by the anvil 110 and the welding head 120 can be constantly maintained to prevent the overlapping surface 30 from being damaged or deformed, thereby preventing welding defects from occurring.

[0062] In the ultrasonic welding device 100 for secondary batteries according to the first embodiment of the present invention, the thickness of the electrode lead bonded to the electrode assembly may vary according to the use, so the pressing force exerted on the overlapping surface 30 by the anvil 110 and the welding head 120 can be adjusted by reflecting the thickness of the electrode lead 20.

[0063] Electrode lead measuring section

[0064] That is to say, the ultrasonic welding device 100 for secondary batteries according to the first embodiment of the present invention further includes an electrode lead measurement unit 150, and the electrode lead measurement unit 150 measures the thickness of the electrode lead 20 provided on the overlapping surface 30. Therefore, the welding head pressure adjustment unit 141 can increase or decrease the pressing force exerted by the welding head 120 on the overlapping surface 30 according to the thickness value of the electrode lead 20 measured by the electrode lead measurement unit 150, thereby adjusting again the pressure exerted on the overlapping surface 30 by the anvil 110 and the welding head 120.

[0065] The ultrasonic welding device 100 for secondary batteries with the above structure according to the first embodiment of the present invention can reflect the thickness of the electrode lead together with the electrode tab to more constantly adjust the pressure exerted on the overlapping surface 30.

[0066] The ultrasonic welding device 100 for secondary batteries according to the first embodiment of the present invention further includes a height adjustment unit 160, and the height adjustment unit 160 constantly maintains the height of the overlapping surface provided between the anvil and the welding head.

[0067] Height adjusting section

[0068] The height adjustment unit 160 measures the height of the overlapping surface 30 provided between the anvil 110 and the welding head 120 with respect to the ground 40 to adjust the height, thereby constantly maintaining the height of the overlapping surface 30 provided between the anvil 110 and the welding head 120. That is to say, the electrode assembly can be raised or lowered, thereby constantly maintaining the height of the overlapping surface 30 provided between the anvil 110 and the welding head 120 and connected to the electrode assembly 10.

[0069] The ultrasonic welding device 100 for secondary batteries according to the first embodiment of the present invention further includes an arrangement member 170, and the electrode assembly 10 is arranged on the arrangement member 170.

[0070] Arrangement member

[0071] The electrode assembly 10 can be arranged on the top surface of the arrangement member 170 such that the overlapping surface 30 of the electrode tab 11 provided in the electrode assembly 10 and the electrode lead 20 is stably arranged between the anvil 110 and the welding head 120.

[0072] Therefore, the ultrasonic welding device 100 for secondary batteries according to the first embodiment of the present invention can adjust the pressing force applied to the overlapping surface by the anvil 110 and the welding head 120 to prevent welding defects from occurring in advance.

[0073] Hereinafter, the ultrasonic welding method for secondary batteries according to the first embodiment of the present invention will be described.

[0074] [Ultrasonic Welding Method for Secondary Batteries According to the First Embodiment of the Present Invention]

[0075] As Figure 2 shown, the ultrasonic welding method for secondary batteries according to the first embodiment of the present invention is performed to weld the overlapping surface of the electrode tab provided in the electrode assembly and the electrode lead. The ultrasonic welding method for secondary batteries according to the first embodiment of the present invention includes a setting process (S10), a height adjustment process (S15), an electrode tab measurement process (S20), a pressure adjustment process (S30), and a welding process (S40).

[0076] Setting process

[0077] In the setting process (S10), the electrode assembly 10 is arranged on the top surface of the arrangement member 170. Then, the overlapping surface 30 of the electrode tab 11 provided in the electrode assembly 10 and the electrode lead 20 is arranged between the anvil 110 and the welding head 120, and then the overlapping surface 30 is arranged to be in close contact with the top surface of the anvil 110.

[0078] Height adjusting process

[0079] In the height adjustment process (S15), the height of the overlapping surface 30 provided between the anvil 110 and the welding head 120 is measured by the height adjustment unit 160, and then the measured value is compared with the input reference value. Here, when the comparison value is within the set range, it is determined to be normal, and when the comparison value is outside the set range, the height of the overlapping surface 30 is adjusted by the difference value. Thus, the height of the overlapping surface 30 provided between the anvil 110 and the welding head 120 can be adjusted to be maintained at a constant height.

[0080] Electrode tab measuring process

[0081] In the electrode tab measurement process (S20), the thickness of the electrode tab 11 provided on the overlapping surface 30 is measured by the electrode tab measurement unit 130. Here, the electrode tab measurement unit 130 measures the thickness at three or more positions of the electrode tab 11 provided on the overlapping surface 30.

[0082] Pressure regulating process

[0083] In the pressure adjustment process (S30), according to the thickness value of the electrode tab 11 measured in the electrode tab measurement process (S20), the pressure applied to the overlapping surface 30 by the anvil 110 and the welding head 120 is adjusted by the pressure adjustment device 140.

[0084] That is to say, the pressure adjustment device 140 increases or decreases the pressing force applied by the welding head 120 to the overlapping surface 30 through the welding head pressure adjustment unit 141 according to the thickness value of the electrode tab 11 measured in the electrode tab measurement process (S20), so as to adjust the pressure applied to the overlapping surface 30 by the anvil 110 and the welding head 120. Here, the welding head pressure adjustment unit 141 adjusts the pressing force of the welding head 120 by comparing the average value of the thickness of the electrode tab 11 measured by the electrode tab measurement unit 130 at three or more positions of the electrode tab 11 with the preset thickness reference value of the electrode tab 11.

[0085] Welding process

[0086] In the welding process, ultrasonic waves are applied in a state where the welding head 120 and the anvil 110 whose pressure has been adjusted press the overlapping surface 30 to perform welding.

[0087] When the above processes are completed, an electrode assembly in which the electrode tab and the electrode lead are uniformly welded can be manufactured.

[0088] Hereinafter, in the description of another embodiment of the present invention, components having the same functions as those in the above embodiment are given the same reference numerals in the drawings, and thus repeated descriptions will be omitted.

[0089] [Ultrasonic Welding Device for Secondary Battery According to the Second Embodiment of the Present Invention]

[0090] As Figure 3 shown in, the ultrasonic welding device 100 for a secondary battery according to the second embodiment of the present invention includes: an anvil 110, on which the overlapping surface 30 of the electrode tab 11 and the electrode lead 20 provided in the electrode assembly 10 is disposed; a welding head 120, which welds the overlapping surface 30 of the electrode tab 11 and the electrode lead 20 disposed on the anvil 110; an electrode tab measuring unit 130, which measures the thickness of the electrode tab 11 provided on the overlapping surface 30; and a pressure adjusting device 140, which adjusts the pressure applied to the overlapping surface 30 by the anvil 110 and the welding head 120 according to the thickness value of the electrode tab 11 measured by the electrode tab measuring unit 130.

[0091] The anvil 110, the welding head 120, and the electrode tab measuring unit 130 have the same structure and function as the above-mentioned anvil, welding head, and electrode tab measuring unit, respectively, and thus the repeated description will be omitted.

[0092] Herein, the pressure adjusting device 140 includes an anvil pressure adjusting unit 142, which increases or decreases the pressing force applied by the anvil 110 to the overlapping surface 30 according to the thickness value of the electrode tab 11 measured by the electrode tab measuring unit 130, so as to adjust the pressure applied to the overlapping surface 30 by the anvil 110 and the welding head 120.

[0093] The anvil pressure adjusting unit 142 includes: an anvil control member 142a, which calculates the pressure value of the anvil 110 by comparing the thickness value measured by the electrode tab measuring unit 130 with a preset thickness reference value of the electrode tab 11; and an anvil pressure adjusting member 142b, which increases or decreases the pressing force applied by the anvil 110 to the overlapping surface 30 according to the pressure value of the anvil 110 calculated by the anvil control member 142a.

[0094] The anvil pressure adjusting member 142b can adjust the pressure of the anvil by adjusting the distance between the overlapping surface and the anvil by raising or lowering the anvil 110 in the direction of the overlapping surface 30.

[0095] Therefore, the ultrasonic welding device 100 for a secondary battery according to the second embodiment of the present invention may include a pressure adjusting device 140 provided with an anvil pressure adjusting unit 142, so that the pressing force applied to the overlapping surface by the anvil 110 and the welding head 120 can be constantly maintained to prevent the overlapping surface 30 from being damaged or deformed, thereby preventing welding defects from occurring.

[0096] Hereinafter, the ultrasonic welding method for a secondary battery according to the second embodiment of the present invention will be described.

[0097] [Ultrasonic welding method for secondary battery according to the second embodiment of the present invention]

[0098] Perform the ultrasonic welding method for secondary battery according to the second embodiment of the present invention to weld the overlapping surface of the electrode tab and the electrode lead provided in the electrode assembly. The ultrasonic welding method for secondary battery according to the second embodiment of the present invention includes a setting process (S10), a height adjustment process (S15), an electrode tab measurement process (S20), a pressure adjustment process (S30), and a welding process (S40).

[0099] Here, the setting process (S10), the height adjustment process (S15), the electrode tab measurement process (S20), and the welding process (S40) are the same as the above-mentioned setting process (S10), height adjustment process (S15), electrode tab measurement process (S20), and welding process (S40), so the repeated description will be omitted.

[0100] In the pressure adjustment process (S30), according to the thickness value of the electrode tab measured in the electrode tab measurement process (S20), the pressure applied to the overlapping surface by the anvil and the welding head is adjusted by the anvil pressure adjustment unit 142.

[0101] That is to say, in the pressure adjustment process (S30), the pressing force applied by the anvil to the overlapping surface can be increased or decreased according to the thickness value of the electrode tab measured in the electrode tab measurement process, so as to adjust the pressure applied to the overlapping surface by the anvil and the welding head.

[0102] [Experimental example]

[0103] Experiment preparation

[0104] Use the ultrasonic device 100 for secondary battery according to the first embodiment of the present invention to weld the overlapping surfaces of the electrode tabs and the electrode leads provided in Preparation Examples 1 to 5. Here, the thickness of the electrode tab provided on the overlapping surface is 0.5 mm, and the thickness of the electrode lead provided on the overlapping surface is 0.2 mm. Therefore, the thickness of the overlapping surface is 0.7 mm.

[0105] In particular, based on the thickness of the overlapping surface, the gap between the anvil and the welding head is changed in units of 0.05 mm, and then the overlapping surfaces of the electrode tabs and the electrode leads provided in Preparation Examples 1 to 5 are welded.

[0106] In Preparation Example 1, the overlapping surface of the electrode tab and the electrode lead is welded in a state where the gap between the anvil and the welding head is separated by a distance of 0.6 mm smaller than the thickness of the overlapping surface, and the pressing force is measured at this time.

[0107] In Preparation Example 2, the overlapping surface of the electrode tab and the electrode lead is welded in a state where the gap between the anvil and the welding head is spaced 0.65 mm, which is smaller than the thickness of the overlapping surface, and the pressing force is measured at this time.

[0108] In Preparation Example 3, the overlapping surface of the electrode tab and the electrode lead is welded in a state where the gap between the anvil and the welding head is spaced 0.7 mm, which is equal to the thickness of the overlapping surface, and the pressing force is measured at this time.

[0109] In Preparation Example 4, the overlapping surface of the electrode tab and the electrode lead is welded in a state where the gap between the anvil and the welding head is spaced 0.75 mm, which is larger than the thickness of the overlapping surface, and the pressing force is measured at this time.

[0110] In Preparation Example 5, the overlapping surface of the electrode tab and the electrode lead is welded in a state where the gap between the anvil and the welding head is spaced 0.8 mm, which is larger than the thickness of the overlapping surface, and the pressing force is measured at this time.

[0111] Here, the electrode tab includes a negative electrode tab and a positive electrode tab, and the electrode lead includes a negative electrode lead and a positive electrode lead. That is, the negative electrode tab and the negative electrode lead are welded for 0.36 seconds, and at this time, the amplitude is 41%. The positive electrode tab and the positive electrode lead are welded for 0.17 seconds, and at this time, the amplitude is 37%.

[0112] Tensile strength test

[0113] As the measurement result of the tensile strength of the welded portion formed on the overlapping surface of the negative electrode tab and the negative electrode lead in Preparation Examples 1 to 5, a graph as shown in Figure 4 can be obtained.

[0114] As the measurement result of the tensile strength of the welded portion formed on the overlapping surface of the positive electrode tab and the positive electrode lead in Preparation Examples 1 to 5, a graph as shown in Figure 5 can be obtained.

[0115] Here, the control tensile strength of the negative electrode is set to 80 kgf. In addition, the control tensile strength of the positive electrode is set to 60 kgf. Here, a tensile strength of 80 kgf corresponds to a pressing force of 150 kgf, and a tensile strength of 60 kgf corresponds to a pressing force of 75 kgf. In addition, the welded portion has a length of 44 mm, a width of 3 mm, and a thickness of 0.5 mm.

[0116] Pressing force test results by tensile strength

[0117] As a result of the test result of the overlapping surface of the welded negative electrode tab and the negative electrode lead, referring to Figure 4, in Preparation Examples 1 to 3, it can be seen that since the measured tensile strength is greater than the control tensile strength, the welding is normal. That is to say, it can be seen that since the pressing force in Preparation Example 1 was measured as 164 kgf, the pressing force in Preparation Example 2 was measured as 156 kgf, and the pressing force in Preparation Example 3 was measured as 150 kgf, the pressing force is equal to or greater than 150 kgf as the control pressing force, so the welding is normal. In addition, in Preparation Examples 4 and 5, it can be seen that since the measured pressing force is equal to or less than the control tensile strength, the pressing force must be adjusted, or the welding is defective. That is to say, it can be seen that since the pressing force in Preparation Example 4 was measured as 141 kgf and the pressing force in Preparation Example 5 was measured as 133 kgf, the measured pressing force is less than 150 kgf as the control pressing force, so the pressing force must be adjusted, or the welding is defective.

[0118] As a result of the test results of the overlapping surface of the positive electrode plate and the positive electrode lead to be welded, refer to Figure 5 , in Preparation Examples 1 to 3, it can be seen that since the measured tensile strength is greater than the control tensile strength, the welding is normal. That is to say, it can be seen that since the pressing force in Preparation Example 1 was measured as 97 kgf, the pressing force in Preparation Example 2 was measured as 88 kgf, and the pressing force in Preparation Example 3 was measured as 82 kgf, the pressing force is equal to or greater than 75 kgf as the control pressing force, and the welding is normal. In addition, in Preparation Examples 4 and 5, it can be seen that since the measured pressing force is equal to or less than the control tensile strength, the pressing force must be adjusted, or the welding is defective. That is to say, it can be seen that since the pressing force in Preparation Example 4 was measured as 73 kgf and the pressing force in Preparation Example 5 was measured as 68 kgf, the measured pressing force is less than 75 kgf as the control pressing force, so the pressing force must be adjusted, or the welding is defective.

[0119] Therefore, as the measurement results of the tensile strength in Preparation Examples 1 to 5, the gap between the adjustable anvil and the welding head can be adjusted to prevent welding defects of the electrode tab and the electrode lead welded by the anvil and the welding head.

[0120] Therefore, the scope of the present invention is defined by the appended claims, rather than by the foregoing description and the exemplary embodiments described herein. Various modifications within the equivalent meaning of the claims of the present invention and within the claims should be considered to be within the scope of the present invention.

[0121] [Description of reference numerals]

[0122] 100: Ultrasonic welding device for secondary battery

[0123] 110: Anvil

[0124] 120: Welding head

[0125] 130: Electrode tab measuring section

[0126] 140: Pressure regulating device

[0127] 141: Welding head pressure regulating section

[0128] 141a: Welding head control part

[0129] 141b: Welding head pressure regulating part

[0130] 142: Anvil pressure regulating section

[0131] 150: Electrode lead measuring section

[0132] 160: Height regulating section.

Claims

1. An ultrasonic welding device for a secondary battery, the ultrasonic welding device being configured to weld an overlapping surface of an electrode tab and an electrode lead provided in an electrode assembly, the ultrasonic welding device comprising: An anvil, on which the overlapping surface of the electrode tab and the electrode lead is provided; A welding head configured to apply ultrasonic waves to the overlapping surface of the electrode tab and the electrode lead provided on the anvil while pressing the overlapping surface; An electrode tab measuring unit configured to measure the thickness of the electrode tab provided on the overlapping surface; A pressure adjusting device configured to adjust the pressure applied to the overlapping surface by the anvil and the welding head according to the thickness value of the electrode tab measured by the electrode tab measuring unit; and A height adjusting unit configured to constantly maintain the height of the overlapping surface provided between the anvil and the welding head, wherein the ultrasonic welding device further includes an electrode lead measuring unit configured to measure the thickness of the electrode lead provided on the overlapping surface, and the pressure adjusting device is configured to re-adjust the pressure applied to the overlapping surface by the anvil and the welding head according to the thickness value of the electrode lead measured by the electrode lead measuring unit, The height adjusting unit can raise or lower the electrode assembly so as to keep the height of the overlapping surface provided between the anvil and the welding head constant.

2. The ultrasonic welding device according to claim 1, wherein the pressure adjusting device includes a welding head pressure adjusting unit configured to increase or decrease the pressing force applied by the welding head to the overlapping surface according to the thickness value of the electrode tab measured by the electrode tab measuring unit, thereby adjusting the pressure applied to the overlapping surface by the anvil and the welding head.

3. The ultrasonic welding device according to claim 2, wherein the welding head pressure adjusting unit comprises: A welding head control member configured to calculate the pressure value of the welding head by comparing the thickness value measured by the electrode tab measuring unit with a preset thickness reference value of the electrode tab; and A welding head pressure adjusting member configured to increase or decrease the pressing force applied by the welding head to the overlapping surface according to the pressure value of the welding head calculated by the welding head control member.

4. The ultrasonic welding device according to claim 3, wherein the welding head pressure adjusting member is configured to raise or lower the welding head in the direction of the overlapping surface, thereby adjusting the pressure of the welding head through the distance between the overlapping surface and the welding head.

5. The ultrasonic welding device according to claim 3, wherein three or more electrode tab measuring units are installed at the electrode tab provided on the overlapping surface to measure the thicknesses at three or more positions of the electrode tab, and the welding head control member is configured to set the average value of the three or more thickness values of the electrode tab measured by the electrode tab measuring unit as the thickness value of the electrode tab.

6. The ultrasonic welding device according to claim 2, wherein the tip pressure adjustment unit is configured to increase or decrease the pressing force applied by the tip to the overlapping surface according to the thickness value of the electrode lead measured by the electrode lead measurement unit, so as to adjust again the pressure applied by the anvil and the tip to the overlapping surface.

7. The ultrasonic welding device according to claim 1, wherein the pressure adjustment device includes an anvil pressure adjustment unit, and the anvil pressure adjustment unit is configured to increase or decrease the pressing force applied by the anvil to the overlapping surface according to the thickness value of the electrode tab measured by the electrode tab measurement unit, so as to adjust the pressure applied by the anvil and the tip to the overlapping surface.

8. The ultrasonic welding device according to claim 7, wherein the anvil pressure adjustment unit includes: an anvil control member configured to calculate the pressure value of the anvil by comparing the thickness value measured by the electrode tab measurement unit with a preset thickness reference value of the electrode tab; and an anvil pressure adjustment member configured to increase or decrease the pressing force applied by the anvil to the overlapping surface according to the pressure value of the anvil calculated by the anvil control member.

9. The ultrasonic welding device according to claim 8, wherein the anvil pressure adjustment member is configured to move the anvil up or down in the direction of the overlapping surface, so as to adjust the pressure of the anvil by adjusting the distance between the overlapping surface and the anvil.

10. The ultrasonic welding device according to claim 1, further comprising an arrangement member configured to arrange the electrode tab and the electrode lead provided in the electrode assembly in a state where they overlap each other.

11. An ultrasonic welding method for a secondary battery, the ultrasonic welding method being performed to weld the overlapping surface of the electrode tab and the electrode lead provided in the electrode assembly, the ultrasonic welding method comprises: a setting step of setting the overlapping surface of the electrode tab and the electrode lead provided in the electrode assembly between the tip and the anvil and setting the overlapping surface on the top surface of the anvil; an electrode tab measurement step of measuring the thickness of the electrode tab provided on the overlapping surface; a pressure adjustment step of adjusting the pressure applied by the anvil and the tip to the overlapping surface according to the thickness value of the electrode tab measured in the electrode tab measurement step; and a welding step of applying ultrasonic waves to the overlapping surface while pressing the overlapping surface by the tip and the anvil whose pressure has been adjusted, further comprising a height adjustment step between the setting step and the electrode tab measurement step, the height adjustment step adjusting the height of the overlapping surface to be kept constant by a height adjustment unit. The ultrasonic welding method further includes an electrode lead measurement process of measuring the thickness of the electrode lead disposed on the overlapping surface, and the pressure adjustment process re-adjusts the pressure applied to the overlapping surface by the anvil and the welding head according to the thickness value of the electrode lead measured in the electrode lead measurement process. The height adjustment unit can raise or lower the electrode assembly, so as to keep the height of the overlapping surface disposed between the anvil and the welding head constant.

12. The ultrasonic welding method according to claim 11, wherein in the pressure adjustment process, the pressing force applied by the welding head to the overlapping surface is increased or decreased according to the thickness value of the electrode tab measured in the electrode tab measurement process, so as to adjust the pressure applied to the overlapping surface by the anvil and the welding head.

13. The ultrasonic welding method according to claim 11, wherein in the pressure adjustment process, the pressing force applied by the anvil to the overlapping surface is increased or decreased according to the thickness value of the electrode tab measured in the electrode tab measurement process, so as to adjust the pressure applied to the overlapping surface by the anvil and the welding head.

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