Secondary battery and ultrasonic welding device and welding method for secondary battery

Abstract

The present invention includes: an anvil, which is configured so that the overlapping surfaces of the electrode tabs and electrode leads arranged in the electrode assembly are arranged on the anvil; a welding head, which is configured to weld the overlapping surfaces arranged on the anvil; and an inspection component, which is configured to inspect the horizontality of the opposing component relative to the overlapping surface based on an overlapping surface level value and an opposing level value, wherein the overlapping surface level value is the level value of the overlapping surface relative to a predetermined reference plane, the opposing level value is the level value of the opposing component relative to the predetermined reference plane, and the opposing component is one of a welding portion of the welding head facing the overlapping surface and a setting portion of the anvil on which the overlapping surface is arranged.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2020-0089211, filed on Jul. 17, 2020, and Korean Patent Application No. 10-2021-0081002, filed on Jun. 22, 2021, which are hereby incorporated by reference in their entirety. Technical Field

[0003] The present invention relates to a secondary battery and an ultrasonic welding device and a welding method for the secondary battery, and more particularly, to a secondary battery in which overlapping surfaces of an electrode tab and an electrode lead are uniformly welded and an ultrasonic welding device and a welding method for the secondary battery. Background Art

[0004] Generally, a secondary battery refers to a battery that can be charged and discharged, unlike a non-rechargeable primary battery. Such secondary batteries are being widely used in high-tech electronic fields such as mobile phones, notebook computers, and camcorders.

[0005] Secondary batteries are divided into can-type secondary batteries in which the electrode assembly is built into a metal can, and pouch-type secondary batteries in which the electrode assembly is built into a bag. In addition, the pouch-type secondary battery includes: an electrode assembly, an electrode lead coupled to an electrode tab of the electrode assembly, and a bag that accommodates the electrode assembly in a state in which the front end of the electrode lead is led out.

[0006] The electrode tabs and electrode leads of the electrode assembly are joined by welding, and an ultrasonic welding device is used.

[0007] The ultrasonic welding device comprises: an anvil, on which the overlapping surfaces of the electrode contact piece and the electrode lead are arranged; and a welding head, which applies ultrasonic waves to the overlapping surfaces arranged on the anvil, thereby welding the overlapping surfaces.

[0008] However, the ultrasonic welding device has a problem in that when the anvil and the horn are not disposed horizontally with respect to the overlapping surface, the entire overlapping surface is not uniformly welded, resulting in welding defects.

[0009] In more detail, in the ultrasonic welding device according to the related art, when the anvil and the horn are not horizontally disposed with respect to the overlapping surface, welding energy is not uniformly transmitted to the entire overlapping surface, thereby causing welding defects. Summary of the invention

[0010] Technical issues

[0011] An object of the present invention for solving the above-mentioned problems is to provide a secondary battery and an ultrasonic welding device and a welding method for a secondary battery, wherein the horizontality of an anvil and a welding head are adjusted to be horizontally arranged relative to the overlapping surface of the electrode tab and the electrode lead, so that the welding energy is uniformly (equally) transmitted to the overlapping surface of the electrode tab and the electrode lead, thereby uniformly welding the entire overlapping surface, thereby improving the welding quality.

[0012] Technical Solution

[0013] In order to achieve the above-mentioned purpose, the ultrasonic welding device according to the present invention includes: an anvil, which is configured so that the overlapping surfaces of the electrode tabs and electrode leads arranged in the electrode assembly are arranged on the anvil; a welding head, which is configured to weld the overlapping surfaces arranged on the anvil; and an inspection component, which is configured to inspect the horizontality of the opposing component relative to the overlapping surface based on an overlapping surface level value and an opposing level value, wherein the overlapping surface level value is the level value of the overlapping surface relative to a predetermined reference plane, and the opposing level value is the level value of the opposing component relative to the predetermined reference plane, and the opposing component is one of a welding portion of the welding head facing the overlapping surface and a setting portion of the anvil on which the overlapping surface is set.

[0014] When the horizontality is determined to be within a predetermined normal range by the inspection member, the horn may be configured to apply ultrasonic waves to the overlapping surface in a state where the welding portion of the horn is supported on the overlapping surface.

[0015] The ultrasonic welding device may further include: an overlapping surface measuring component, which is configured to measure the overlapping surface level value of the overlapping surface relative to the predetermined reference plane; and an opposing measuring component, which is configured to measure the opposing level value, the opposing level value is the level value of the opposing component relative to the predetermined reference plane, and the opposing component is one of the welding portion of the welding head facing the overlapping surface and the setting portion of the anvil on which the overlapping surface is set.

[0016] The ultrasonic welding device may further include an angle adjustment member configured to adjust the angle of the opposing member by a difference between the overlapping surface level and the opposing level.

[0017] The angle adjustment member may be configured to adjust the angle of the opposing member by the difference between the overlapping surface level value and the opposing level value when the checking member determines that the level is outside a predetermined normal range.

[0018] When the predetermined reference plane is set to an angle of 0°, the overlapping surface horizontal value may include the inclination angle of the overlapping surface in the full length direction and the inclination angle of the overlapping surface in the full width direction. When the predetermined reference plane is set to an angle of 0°, the opposing horizontal value may include the inclination angle of the opposing member in the full length direction and the inclination angle of the opposing member in the full width direction, and the inspection member may be configured to compare the inclination angle of the overlapping surface in the full length direction with the inclination angle of the opposing member in the full length direction, and to compare the inclination angle of the overlapping surface in the full width direction with the inclination angle of the opposing member in the full width direction.

[0019] The predetermined normal range may be set to an angle of 0.30° or less.

[0020] According to the present invention, the ultrasonic welding method for secondary batteries includes: step (a), setting the overlapping surface of the electrode tab and the electrode lead arranged in the electrode assembly on the anvil; step (b), setting a welding head for welding the overlapping surface arranged on the anvil; and step (c), checking the horizontality of the opposing member relative to the overlapping surface based on the overlapping surface level value and the opposing level value, the overlapping surface level value is the level value of the overlapping surface relative to the predetermined reference plane, the opposing level value is the level value of the opposing member relative to the predetermined reference plane, and the opposing member is one of the welding part of the welding head facing the overlapping surface and the setting part of the anvil on which the overlapping surface is set.

[0021] The step (c) may further include a step of applying ultrasonic waves in a state where the welding portion of the welding head is supported on the overlapping surface when it is determined that the horizontality is within a predetermined normal range.

[0022] The step (c) may further include the step of adjusting the angle of the opposing member by a difference between the overlapping surface level and the opposing level when it is determined that the level is outside a predetermined normal range.

[0023] The step (a) may further include a step of measuring a level of the overlapping surface, wherein the level of the overlapping surface is a level of the overlapping surface relative to the predetermined reference surface.

[0024] The process (b) may further include a process of measuring the opposing level value, wherein the opposing level value is a level value of the opposing member relative to the predetermined reference plane, and the opposing member is one of the welding portion of the welding head facing the overlapping surface and the setting portion of the anvil on which the overlapping surface is set.

[0025] The predetermined normal range may be set to an angle of 0.30° or less.

[0026] The secondary battery according to the present invention includes an electrode assembly provided with an electrode tab and an electrode lead, wherein an overlapping surface bonded by ultrasonic welding is provided at a portion where the electrode tab and the electrode lead overlap each other, and the overlapping surface has the same overall bonding force in the full length direction and the full width direction of the overlapping surface.

[0027] Beneficial Effects

[0028] The ultrasonic welding device for secondary batteries of the present invention includes an inspection member, which checks the horizontality of the anvil and the welding head relative to the overlapping surface of the electrode tab and the electrode lead. That is, the inspection member can check the horizontality of the opposing member relative to the overlapping surface based on the overlapping surface level value and the opposing level value, the overlapping surface level value is the horizontal value of the overlapping surface relative to a predetermined reference surface, the opposing level value is the horizontal value of the opposing member relative to the reference surface, and the opposing member is one of the welding part of the welding head facing the overlapping surface and the setting part of the anvil on which the overlapping surface is set. Therefore, it can be checked whether the anvil and the welding head press the entire overlapping surface evenly, and as a result, it can be checked whether a defect occurs.

[0029] In addition, the ultrasonic welding device for a secondary battery according to the present invention may include an angle adjustment member for correcting the angle of the anvil and the horn relative to the overlapping surface. That is, the angle adjustment member may be configured to adjust the angle of the opposing member to the difference between the overlapping surface level value and the opposing level value when the inspection member determines that the horizontality is outside the predetermined normal range. Therefore, the anvil and the horn can uniformly press the entire overlapping surface, and as a result, the bonding force of the entire overlapping surface can be uniform, thereby preventing defects from occurring. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a cross-sectional view of a secondary battery according to a first embodiment of the present invention.

[0031] Figure 2 is a side view illustrating an ultrasonic welding device for a secondary battery according to a second embodiment of the present invention.

[0032] Figure 3 is a side view illustrating a horn measuring member and a horn angle adjusting member of an ultrasonic welding device for a secondary battery according to a second embodiment of the present invention.

[0033] Figure 4 yes Figure 3 Front view of .

[0034] Figure 5 is a side view illustrating an anvil measuring member and an anvil angle adjusting member of an ultrasonic welding device for a secondary battery according to a second embodiment of the present invention.

[0035] Figure 6 yes Figure 5 Front view of .

[0036] Figure 7 is a flowchart illustrating an ultrasonic welding method for a secondary battery according to a second embodiment of the present invention.

[0037] Figures 8 to 10 This is a picture taken of overlapping surfaces welded by the ultrasonic welding device for a secondary battery according to the second embodiment of the present invention.

[0038] Fig.11 is a graph illustrating results obtained by measuring the tensile strength of a negative electrode tab and a negative electrode lead welded by an ultrasonic welding apparatus for a secondary battery according to a second embodiment of the present invention.

[0039] Fig.12 is a graph illustrating results obtained by measuring the tensile strength of a positive electrode tab and a positive electrode lead welded by an ultrasonic welding apparatus for a secondary battery according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0040] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in a manner that a person of ordinary skill in the art to which the present invention belongs 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 accompanying drawings, any unnecessary content for describing the present invention will be omitted for the sake of clarity, and in addition, the same reference numerals in the drawings represent the same elements.

[0041] [Secondary Battery According to First Embodiment of the Present Invention]

[0042] like Figure 1 As shown, a secondary battery 1 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 combined with the electrode tab 11, and a bag 50 accommodating the electrode assembly 10 in a state where a front end of the electrode lead 20 is led out to the outside.

[0043] Here, the electrode tab 11 and the electrode lead 20 are arranged to partially overlap each other, and then the overlapping portion of the electrode tab 11 and the electrode lead 20 is ultrasonically welded to bond the electrode tab 11 to the electrode lead 20. That is, an overlapping surface 30 bonded by ultrasonic welding is provided at the overlapping portion of the electrode tab and the electrode lead. Here, the ultrasonic welding device for a secondary battery according to the second embodiment of the present invention is used.

[0044] In particular, since the overlapping surface 30 can be ultrasonically welded by the ultrasonic welding device for a secondary battery according to the second embodiment of the present invention, the overlapping surface 30 is Figure 1 The overall bonding strength in the left-right direction when viewed in the middle) and the full width direction (in the Figure 1 The overall bonding strength in the front-to-back direction (when viewed in the middle) can be provided uniformly (equally), thereby improving the welding quality.

[0045] Hereinafter, an ultrasonic welding device for a secondary battery according to a second embodiment of the present invention will be described in detail.

[0046] [Ultrasonic welding device for secondary battery according to second embodiment of the present invention]

[0047] like Figures 2 to 6 As shown in the figure, an ultrasonic welding device 100 for a secondary battery according to a second embodiment of the present invention includes: an anvil 110, on which the overlapping surfaces 30 of the electrode tabs 11 and the electrode leads 20 provided in the electrode assembly 10 are provided; and a welding head 120, which is configured to weld the overlapping surfaces 30 provided on the anvil 110.

[0048] That is, in the ultrasonic welding device 100 for a secondary battery according to the second embodiment of the present invention, when 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 by the welding head 120 to connect and combine the electrode tab 11 to the electrode lead 20.

[0049] In the ultrasonic welding device 100 for a secondary battery according to the second embodiment of the present invention, when the welding portion 121 of the welding head 120 or the setting portion 111 of the anvil on which the overlapping surface is set has a horizontality different from the horizontality of the overlapping surface 30, the entire overlapping surface 30 will not be uniformly pressed by the anvil 110 and the welding head 120, so that a difference in welding energy applied to the entire overlapping surface 30 will occur, thereby causing welding defects.

[0050] In order to solve the above problems, the ultrasonic welding device 100 for a secondary battery according to the second embodiment of the present invention includes an inspection member for inspecting the horizontality of the setting portion 111 of the anvil or the welding portion 121 of the horn 120 relative to the overlapping surface 30. The inspection member 150 can inspect whether the entire overlapping surface 30 is uniformly pressed by the anvil 110 and the horn 120 to inspect whether a welding defect occurs.

[0051] That is, the inspection component 150 can check the horizontality of the opposing component relative to the overlapping surface 30 based on the overlapping surface level value and the opposing level value, wherein the overlapping surface level value is the level value of the overlapping surface 30 relative to the predetermined reference plane 40, and the opposing level value is the level value of the opposing component relative to the reference plane, and the opposing component is one of the welding part 121 of the welding head 120 and the setting part 111 of the anvil on which the overlapping surface is set.

[0052] Here, when the horizontality is determined to be within a predetermined normal range by the inspection component 150, the welding head 120 is configured to apply ultrasonic waves when the welding portion 121 of the welding head 120 is supported on the overlapping surface 30, so that the welding energy applied to the entire overlapping surface 30 can be uniform, thereby improving the welding quality due to uniform welding on the entire overlapping surface.

[0053] Therefore, the ultrasonic welding device 100 for a secondary battery according to the second embodiment of the present invention may include an inspection component to check the horizontality of the setting portion 111 of the anvil 110 or the welding portion 121 of the welding head 120 relative to the overlapping surface 30, so as to check whether the entire overlapping surface 30 is evenly pressed, and finally check whether a welding defect occurs.

[0054] The ultrasonic welding device 100 for a secondary battery according to the second embodiment of the present invention includes: an overlapping surface measuring member 130, the overlapping surface measuring member 130 measures the overlapping surface level value, which is the level value of the overlapping surface 30 relative to a predetermined reference plane 40; and an opposing measuring member, the opposing measuring member measures the opposing level value, which is the level value of the opposing member relative to the reference plane 40, and the opposing member is one of the welding portion 121 of the welding head 120 facing the overlapping surface 30 and the setting portion 111 of the anvil 110 on which the overlapping surface 30 is set.

[0055] The overlapping surface measuring member 130 is disposed near the overlapping surface 30 of the electrode tab 11 and the electrode lead 20 to measure the level of the overlapping surface 30 relative to the reference surface 40. That is, the overlapping surface measuring member 130 calculates the overlapping surface level at which the overlapping surface 30 has an inclination angle relative to the reference surface 40.

[0056] On the other hand, the overlap surface measuring member 130 is set at at least three positions on the overlap surface 30, so that the overlap surface measuring member 130 can measure the measured level values ​​of the overlap surface 30 at three or more positions, thereby calculating the overlap surface level value as the average value of the level values ​​measured at the three or more positions.

[0057] When the reference plane is set to an angle of 0°, the overlapping surface level includes the inclination angle A1° of the overlapping surface 30 in the full length direction and the inclination angle A2° of the overlapping surface 30 in the full width direction. That is, the overlapping surface measuring member 130 measures the overlapping surface level relative to the reference plane 40 including the inclination angle A1° of the overlapping surface in the full length direction and the inclination angle A2° of the overlapping surface in the full width direction.

[0058] The opposing measuring member measures an opposing level value, which is a level value of an opposing member relative to the reference surface 40, and the opposing member is one of a welding portion 121 of a welding head 120 facing the overlapping surface 30 and a setting portion 111 of an anvil 110 on which the overlapping surface 30 is set. That is, the opposing measuring member measures the opposing level value to determine how many degrees of inclination angle the opposing member has relative to the overlapping surface.

[0059] In a state where the reference plane or the overlapping plane is set to an angle of 0°, the opposing horizontal value includes the inclination angle of the opposing member in the full length direction and the inclination angle of the opposing member in the full width direction. Therefore, the inspection member is configured to compare the inclination angle of the overlapping plane in the full length direction with the inclination angle of the opposing member in the full length direction, and is configured to compare the inclination angle of the overlapping plane in the full width direction with the inclination angle of the opposing member in the full width direction.

[0060] For example, the opposing measurement components include a horn measurement component 140 and an anvil measurement component 170 .

[0061] The horn measuring member 140 measures the level of the welded portion of the horn 120 facing the overlapped surface 30 relative to the reference plane 40. In a state where the reference plane 40 is set at an angle of 0°, the level of the welded portion of the horn includes the inclination angle B1° of the horn 120 in the full length direction and the inclination angle B2° of the horn 120 in the full width direction. That is, the horn measuring member 140 measures the level of the welded portion of the horn including the inclination angle B1° of the horn 120 in the full length direction and the inclination angle B2° of the horn 120 in the full width direction relative to the reference plane 40.

[0062] That is, the inspection member 150 compares the overlapped surface level value measured by the overlapped surface measuring member 130 with the level value of the welded portion measured by the welding head measuring member 140. Then, when it is determined that the difference is within the normal range, it is determined to be normal, and on the other hand, when it is determined that the difference is outside the normal range, it is determined to be defective.

[0063] For example, the inspection component 150 compares the inclination angle A1° of the overlapping surface 30 in the full length direction with the inclination angle B1° of the welding head 120 in the full length direction to calculate the difference of the welding head in the full length direction, and also compares the inclination angle A2° of the overlapping surface 30 in the full width direction with the inclination angle B2° of the welding head 120 in the full width direction to calculate the difference of the welding head in the full width direction.

[0064] Therefore, when the inspection member 150 determines that the difference in the entire length direction of the welding head and the difference in the entire width direction of the welding head are both within the normal range, it is determined to be normal, and if any one is determined to be outside the normal range, it is determined to be defective.

[0065] The anvil measuring member 170 is provided in the anvil 110 to measure a level value of a setting portion 111 of the anvil 110 with respect to the reference surface 40 .

[0066] As an example, in a state where the reference plane 40 is set to an angle of 0°, the arranged horizontal values ​​include the tilt angle C1° of the anvil 110 in the full length direction and the tilt angle C2° of the anvil 110 in the full width direction. That is, the anvil measuring member 170 measures the tilt angle C1° of the anvil 110 in the full length direction and the tilt angle C2° of the anvil 110 in the full width direction relative to the reference plane 40.

[0067] As described above, when the setting portion level value is measured by the anvil measuring member, the inspection member 150 compares the setting portion level value of the anvil 110 measured by the anvil measuring member 170 with the overlapping surface level value measured by the overlapping surface measuring member 130. Then, when it is determined that the difference is within the normal range, it is judged to be normal, and on the other hand, when it is determined that the difference is outside the normal range, it is judged to be defective.

[0068] Here, the inspection member 150 compares the inclination angle A1° of the overlapping surface 30 in the full length direction with the inclination angle C1° of the anvil 110 in the full length direction to calculate the difference of the anvil in the full length direction, and also compares the inclination angle A2° of the overlapping surface 30 in the full width direction with the inclination angle C2° of the anvil 110 in the full width direction to calculate the difference of the anvil in the full width direction.

[0069] Therefore, when the inspection member 150 determines that the difference in the entire length direction of the anvil and the difference in the entire width direction of the anvil are both within the normal range, it is judged to be normal, and if either one is determined to be outside the normal range, it is judged to be defective.

[0070] The ultrasonic welding device 100 for a secondary battery according to the second embodiment of the present invention having the above configuration may include an overlapping surface measuring member 130 and an opposing measuring member to accurately confirm the horizontality of each of the horn 120 and the anvil relative to the overlapping surface, thereby accurately confirming the possibility of occurrence of welding defects.

[0071] Here, the reference surface 40 may be the ground or a support surface of a workbench on which the ultrasonic welding device is installed.

[0072] The ultrasonic welding device 100 for a secondary battery according to the second embodiment of the present invention further includes an angle adjustment member which adjusts the angle of the opposing member by a difference between the overlapping surface level and the opposing level when the level is determined to be defective.

[0073] That is, when the horizontality is determined to be outside the predetermined normal range by the inspection member 150, the angle adjustment member can adjust the difference between the angle of the opposed member and the opposed horizontal value. Thus, the horizontality of the opposed member relative to the overlap surface 30 can be adjusted to be set within the normal range.

[0074] For example, the angle adjustment member includes a horn angle adjustment member 160 and an anvil angle adjustment member 180 .

[0075] When it is determined to be defective by the inspection member 150, the welding head angle adjustment member 160 rotates the welding head 120 in the left-right direction or the front-back direction by the difference obtained by subtracting the overlapping surface level value from the level value of the welding portion of the welding head 120. Thus, the overlapping surface level value and the level value of the welding portion of the welding head 120 can be set to be consistent with each other relative to the reference surface.

[0076] When it is determined to be defective by the inspection member 150, the anvil angle adjustment member 180 rotates the anvil 110 in the left-right direction or the front-back direction by the difference obtained by subtracting the overlapping surface level value from the setting portion level value of the anvil 110, thereby adjusting the level of the setting portion of the anvil 110. Thus, the overlapping surface level value and the setting portion level value can be set to be consistent with each other relative to the reference surface.

[0077] A normal range may be 0.30° or less, preferably 0.075° or less.

[0078] Therefore, the ultrasonic welding device 100 for a secondary battery according to the second embodiment of the present invention may include an angle adjustment member so that the horizontality of the opposing member relative to the overlapping surface 30 is adjusted to be set within a normal range, so that the entire overlapping surface is welded with uniform welding energy through the anvil and the welding head in a state where the entire overlapping surface is pressed.

[0079] Hereinafter, a welding method using the ultrasonic welding device for a secondary battery according to the second embodiment of the present invention will be described.

[0080] [Ultrasonic welding method for secondary battery according to second embodiment of the present invention]

[0081] like Figure 7 As shown in the figure, an ultrasonic welding method for a secondary battery according to a second embodiment of the present invention is performed to weld the electrode tabs 11 and the electrode leads 20 provided in the electrode assembly 10, and includes: step (a), setting the overlapping surface on an anvil; step (b), setting a welding head for welding the overlapping surface; and step (c), checking the horizontality and welding.

[0082] In step (a), the overlapping surface 30 of the electrode tab 11 and the electrode lead 20 provided in the electrode assembly 10 is placed on the anvil 110 .

[0083] Here, the step (a) further includes a step of measuring an overlapping surface level value, which is a level value of the overlapping surface 30 relative to a predetermined reference surface 40. Here, an overlapping surface measuring member 130 is used.

[0084] That is, the overlapping surface measuring member 130 measures the horizontal value of the overlapping surface 30 of the electrode tab 11 and the electrode lead 20 relative to the reference surface 40. Here, the overlapping surface measuring member 130 measures the inclination angle of the overlapping surface 30 in the full length direction and the inclination angle of the overlapping surface 30 in the full width direction as the overlapping surface horizontal value.

[0085] In step (b), the horn 120 for welding the overlapping surface 30 placed on the anvil 110 is provided.

[0086] Here, the process (b) further includes a process of measuring a counter level value, which is a level value of a counter member relative to a reference plane, the counter member being one of a welding portion 121 of a horn 120 facing the overlapping surface 30 and a setting portion 111 of an anvil 110 on which the overlapping surface 30 is set. Here, a counter measurement member is used, and the counter measurement member includes an anvil measurement member 170 and a horn measurement member 140.

[0087] The anvil measuring member 170 measures the level of the setting portion of the anvil 110 on which the overlapping surface is set relative to the reference surface. The horn measuring member 140 measures the level of the welding portion of the horn facing the overlapping surface 30 relative to the reference surface.

[0088] In step (c), based on the overlapping surface level value (the overlapping surface level value is the level value of the overlapping surface 30 relative to the predetermined reference surface 40) and the opposing level value (the opposing level value is the level value of the opposing member relative to the reference surface), the horizontality of the opposing member relative to the overlapping surface 30 is checked, and the opposing member is one of the welding portion 121 of the welding head 120 and the setting portion 111 of the anvil on which the overlapping surface is set. Here, the inspection member 150 is used.

[0089] The inspection member 150 compares the setting portion level value with the overlapping surface level value to determine whether the difference is within the normal range. As a result, when it is determined that the difference is outside the normal range, it is determined to be defective, and when it is determined that the difference is within the normal range, it is determined to be normal. That is, the inspection member 150 can confirm the difference in the pressing force applied to the entire overlapping surface through the overlapping surface level value and the setting portion level value, and thus can confirm in advance that a welding defect occurs on the overlapping surface 30.

[0090] In addition, the inspection member 150 compares the overlapping surface level value with the welding portion level value to determine whether the difference is within the normal range. As a result, when it is determined that the difference is outside the normal range, it is determined to be defective, and when it is determined that the difference is within the normal range, it is determined to be normal. That is, the inspection member 150 can confirm the difference in the pressing force applied to the entire overlapping surface 30 through the overlapping surface level value and the welding portion level value, and thus can confirm in advance that a welding defect occurs on the overlapping surface 30.

[0091] Here, the process (c) further includes a process of applying ultrasonic waves to weld the overlapping surfaces 30 in a state where the welding portion 121 of the horn 120 is supported on the overlapping surfaces 30 when it is determined that the horizontality is within a predetermined normal range.

[0092] The predetermined normal range may be 0.30° or less, preferably 0.075° or less.

[0093] Step (c) further includes the following steps: when it is determined that the horizontality is outside the predetermined normal range, adjusting the angle of the opposing member by the difference between the overlapping surface level value and the opposing level value. Here, an angle adjustment member is used, and the angle adjustment member includes a welding head angle adjustment member 160 and an anvil angle adjustment member 180.

[0094] That is, the welding head angle adjustment component 160 is configured to adjust the horizontality of the welding head, thereby adjusting the angle of the welding part of the welding head 120 to the difference between the horizontal value of the overlapping surface and the horizontal value of the welding part, so that the horizontal value of the overlapping surface is consistent with the horizontal value of the welding part, thereby uniformly applying the entire overlapping surface or uniformly applying ultrasonic waves to the entire overlapping surface to prevent welding defects.

[0095] The anvil angle adjustment member 180 is configured to adjust the level of the anvil, thereby adjusting the angle of the setting portion of the anvil to the difference between the level of the setting portion of the anvil and the level of the overlapping surface. Thus, the level of the setting portion of the anvil can be consistent with the level of the overlapping surface, thereby preventing welding defects.

[0096] Therefore, in the ultrasonic welding method for a secondary battery according to the second embodiment of the present invention, the entire overlapping surfaces of the electrode tab and the electrode lead can be uniformly welded, and as a result, the welding quality can be improved.

[0097] [Experimental example]

[0098] Experimental Preparation

[0099] An electrode tab and an electrode lead are welded using the ultrasonic welding device 100 for a secondary battery according to the second embodiment of the present invention.

[0100] In preparation example 1, when the difference in horizontality between the anvil 110 and the welding head 120 is 0°, the overlapping surfaces of the electrode tab and the electrode lead are welded, and then the welded overlapping surfaces are photographed. Then, the Figure 8 Here, the unit area (mm2) of the welded overlap is 2 ) has a length of 44 mm and a width of 3 mm.

[0101] In preparation example 2, when the difference in level between the anvil 110 and the welding head 120 is 0.075°, the overlapping surfaces of the electrode tab and the electrode lead are welded, and then the welded overlapping surfaces are photographed. Then, the Fig. 9 Here, the unit area (mm2) of the welded overlapped surface is 2 ) has a length of 44 mm and a width of 3 mm.

[0102] In preparation example 3, when the difference in level between the anvil 110 and the welding head 120 is 0.15°, the overlapping surfaces of the electrode tab and the electrode lead are welded, and then the welded overlapping surfaces are photographed. Fig.10 Here, the unit area (mm2) of the welded overlapped surface is 2 ) has a length of 44 mm and a width of 3 mm.

[0103] Here, the electrode tabs include negative tabs and positive tabs, and the electrode leads include negative leads and positive leads. That is, the welding states of the negative tabs and the negative leads and the welding states of the positive tabs and the positive leads are tested respectively.

[0104] Welding results

[0105] Reference Figure 8 In Preparation Example 1, it can be seen that the entire overlapping surfaces of the electrode tab and the electrode lead are uniformly welded.

[0106] Reference Fig. 9 In Preparation Example 2, it can be seen that a welding defect occurs in a portion on the right side of the entire overlapping surface of the electrode tab and the electrode lead. That is, it is confirmed that a welding defect occurs in the separation portion between the anvil and the welding head.

[0107] Reference Fig.10 In Preparation Example 3, it can be seen that welding defects occur in about half of the entire overlapping surface of the electrode tab and the electrode lead. That is, it can be seen that welding defects occur because about half of the anvil and the welding head are not pressed.

[0108] Therefore, in the ultrasonic welding device 100 for a secondary battery according to the second embodiment of the present invention, as in Preparation Example 1, when welding the overlapping surfaces of the electrode tab and the electrode lead, the horizontalities of the anvil and the welding head are adjusted to be the same to uniformly weld the overlapping surfaces of the electrode tab and the electrode lead, thereby improving the welding quality.

[0109] Tensile strength test

[0110] As the measurement results of the tensile strength of the overlapping surfaces of the negative electrode tab and the negative electrode lead welded in Preparation Examples 1 to 3, it can be obtained that Fig.11 The diagram shown in .

[0111] As the measurement results of the tensile strength of the overlapping surfaces of the positive electrode tab and the positive electrode lead welded in Preparation Examples 1 to 3, it can be obtained that Fig.12 The diagram shown in .

[0112] Here, the managed tensile strength of the negative electrode is set to 80 kgf. In addition, the managed tensile strength of the positive electrode is set to 60 kgf. In addition, the unit area (mm2) of the overlapped surface of the welded negative electrode tab and the negative electrode lead is 2 ) and the unit area of ​​the overlapped surface of the welded positive electrode tab and positive electrode lead (mm 2 ) each having a length of 44 mm, a width of 3 mm and a thickness of 0.5 mm.

[0113] Results of tensile strength test

[0114] As the test result of the overlapped surface of the welded negative electrode tab and the negative electrode lead, refer to Fig.11 In preparation example 1, it was confirmed as normal welding because the measured tensile strength was greater than the managed tensile strength. In addition, in preparation example 2, it was confirmed as normal welding because the measured tensile strength corresponded to the managed tensile strength, and in preparation example 3, it was confirmed as defective welding because the measured tensile strength was less than the managed tensile strength.

[0115] As the test results of the overlapped surface of the welded positive electrode tab and the positive electrode lead, refer to Fig.12 In Preparation Example 1, it was confirmed as normal welding because the measured tensile strength was measured to be greater than the managed tensile strength. In addition, in Preparation Example 2, it was confirmed as normal welding because the measured tensile strength corresponded to the managed tensile strength, and in Preparation Example 3, it was confirmed as defective welding because the measured tensile strength was measured to be less than the managed tensile strength.

[0116] Therefore, as a result of measuring the tensile strength in Preparation Examples 1 to 3, the horizontality of each of the anvil and the horn must be controlled to 0.075° or less, and if controlled as described above, the welding quality of the electrode tab and the electrode lead can be maintained.

[0117] 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 made 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.

[0118] [Description of Reference Numbers]

[0119] 100: Ultrasonic welding device

[0120] 110: Anvil

[0121] 120: welding head

[0122] 130: Overlap surface measurement component

[0123] 140: Welding head measuring component

[0124] 150: Check components

[0125] 160: Welding head angle adjustment component

[0126] 170: Anvil measuring component

[0127] 180: Anvil angle adjustment component.

Claims

1. An ultrasonic welding device, comprising: an anvil, the anvil being arranged so that the overlapping surfaces of the electrode tabs and the electrode leads arranged in the electrode assembly are arranged on the anvil; a welding head configured to weld the overlapping surfaces disposed on the anvil; and an inspection member configured to inspect the horizontality of the opposing member relative to the overlapping surface based on an overlapping surface level value and an opposing level value, wherein the overlapping surface level value is a level value of the overlapping surface relative to a predetermined reference surface, and the opposing level value is a level value of the opposing member relative to the predetermined reference surface, wherein the opposing member is one of a welding portion of the welding head facing the overlapping surface and a setting portion of the anvil on which the overlapping surface is set, Wherein, when the predetermined reference plane is set at an angle of 0°, the horizontal value of the overlapping surface includes the inclination angle of the overlapping surface in the full length direction and the inclination angle of the overlapping surface in the full width direction, In a state where the predetermined reference plane is set at an angle of 0°, the opposing horizontal value includes an inclination angle of the opposing member in the full length direction and an inclination angle of the opposing member in the full width direction, and The inspection member is configured to compare the inclination angle of the overlapping surface in the full length direction with the inclination angle of the opposing member in the full length direction to obtain an angle difference in the full length direction, compare the inclination angle of the overlapping surface in the full width direction with the inclination angle of the opposing member in the full width direction to obtain an angle difference in the full width direction, and determine whether the horizontality is within a predetermined normal range based on the angle difference in the full length direction and the angle difference in the full width direction.

2. The ultrasonic welding device according to claim 1, wherein: When the horizontality is determined to be within a predetermined normal range by the inspection member, the horn is configured to apply ultrasonic waves to the overlapping surface in a state where the welding portion of the horn is supported on the overlapping surface.

3. The ultrasonic welding device according to claim 1, further comprising: an overlap surface measuring member, the overlap surface measuring member being configured to measure a horizontal value of the overlap surface relative to the predetermined reference plane; and The opposing measuring member is configured to measure the opposing level value, wherein the opposing level value is a level value of the opposing member relative to the predetermined reference plane. 4 . The ultrasonic welding device according to claim 1 , further comprising an angle adjustment member configured to adjust the angle of the opposing member by a difference between the overlapping surface level and the opposing level.

5. The ultrasonic welding device according to claim 4, wherein the angle adjustment member is configured to adjust the angle of the opposing member by the difference between the overlapping surface level value and the opposing level value when the inspection member determines that the horizontality is outside a predetermined normal range.

6. The ultrasonic welding device according to claim 2 or 5, wherein the predetermined normal range is set to an angle of 0.30° or less.

7. An ultrasonic welding method for a secondary battery, comprising: Step (a), placing the overlapping surfaces of the electrode tabs and the electrode leads provided in the electrode assembly on an anvil; Step (b), providing a welding head for welding the overlapping surfaces disposed on the anvil; and Step (c), checking the horizontality of the opposing member relative to the overlapping surface based on an overlapping surface level value and an opposing level value, wherein the overlapping surface level value is a level value of the overlapping surface relative to a predetermined reference surface, and the opposing level value is a level value of the opposing member relative to the predetermined reference surface, wherein the opposing member is one of a welding portion of the welding head facing the overlapping surface and a setting portion of the anvil on which the overlapping surface is set, Wherein, when the predetermined reference plane is set at an angle of 0°, the horizontal value of the overlapping surface includes the inclination angle of the overlapping surface in the full length direction and the inclination angle of the overlapping surface in the full width direction, In a state where the predetermined reference plane is set at an angle of 0°, the opposing horizontal value includes an inclination angle of the opposing member in the full length direction and an inclination angle of the opposing member in the full width direction, and The process (c) includes: comparing the inclination angle of the overlapping surface in the full length direction with the inclination angle of the opposing member in the full length direction to obtain the angle difference in the full length direction, comparing the inclination angle of the overlapping surface in the full width direction with the inclination angle of the opposing member in the full width direction to obtain the angle difference in the full width direction, and determining whether the horizontality is within a predetermined normal range based on the angle difference in the full length direction and the angle difference in the full width direction.

8. The ultrasonic welding method according to claim 7, wherein the step (c) further comprises the step of applying ultrasonic waves in a state where the welding portion of the horn is supported on the overlapping surface when it is determined that the horizontality is within a predetermined normal range.

9. The ultrasonic welding method according to claim 7, wherein the step (c) further comprises the step of adjusting the angle of the opposing members by the difference between the overlapping surface level and the opposing level when it is determined that the horizontality is outside a predetermined normal range.

10. The ultrasonic welding method according to claim 7, wherein the step (a) further comprises a step of measuring a level of the overlapping surface, wherein the level of the overlapping surface is a level of the overlapping surface relative to the predetermined reference surface.

11. The ultrasonic welding method according to claim 7, wherein the step (b) further comprises a step of measuring the opposing level value, the opposing level value being a level value of the opposing member relative to the predetermined reference plane.

12. The ultrasonic welding method according to claim 8 or 9, wherein the predetermined normal range is set to an angle of 0.30° or less.

13. A secondary battery manufactured by the ultrasonic welding method according to any one of claims 7 to 12, comprising an electrode assembly provided with an electrode tab and an electrode lead, wherein the portion where the electrode tab and the electrode lead overlap each other is provided with an overlapping surface joined by ultrasonic welding, and The overlapping surface has the same overall bonding force in the entire length direction and the entire width direction of the overlapping surface.

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