阅读说明：本技术 焊头和焊接装置 (Welding head and welding device ) 是由 朴政洙 安昶范 朴日焕 于 2019-10-01 设计创作，主要内容包括：为了解决问题,根据本发明一实施方式的焊头包括：多个突起形成部,多个突起形成部的每一个具有从焊接表面突出并且成行地布置成至少一行的多个突起,多个突起形成部分别在二次电池的电极接片中的最外侧电极接片上形成图案形成部；和无突起部,其设置在多个突起形成部之间并且其中未设置突起以将焊接表面暴露到外部,无突起部在最外侧电极接片上形成无图案部。无突起部具有比突起的每一个的宽度大的宽度。(In order to solve the problem, a bonding tool according to an embodiment of the present invention includes: a plurality of protrusion forming parts each having a plurality of protrusions protruding from the welding surface and arranged in at least one row in a row, the plurality of protrusion forming parts forming pattern forming parts on outermost electrode tabs among the electrode tabs of the secondary battery, respectively; and a non-protrusion portion disposed between the plurality of protrusion forming portions and in which no protrusion is disposed to expose the soldering surface to the outside, the non-protrusion portion forming a non-pattern portion on the outermost electrode tab. The non-protrusion portion has a width greater than a width of each of the protrusions.)

1. A bonding tool, comprising:

a plurality of protrusion forming parts each having a plurality of protrusions protruding from the welding surface and arranged in at least one row in a row, the plurality of protrusion forming parts forming pattern forming parts on outermost electrode tabs among the electrode tabs of the secondary battery, respectively; and

a no-protrusion portion disposed between the plurality of protrusion-forming portions and in which the protrusion is not disposed to expose the welding surface to the outside, the no-protrusion portion forming a no-pattern portion on the outermost electrode tab,

wherein the protrusion-free portion has a width greater than a width of each of the protrusions.

2. The weld head of claim 1, wherein the non-protrusion has a width that is less than twice a width of the protrusion.

3. The weld head of claim 1, wherein the protuberance formation comprises a first protuberance formation and a second protuberance formation, and

in the first protrusion forming portion, the plurality of protrusions are arranged in a plurality of rows in a row.

4. The horn of claim 3, wherein in the second projection formation, the plurality of projections are arranged parallel to the first projection formation.

5. The horn of claim 4, wherein the protuberance formation further comprises a third protuberance formation in which the plurality of protuberances are arranged in parallel with the second protuberance formation.

6. The weld head of claim 5, wherein the non-protrusion comprises:

a first non-protrusion portion provided between the first protrusion forming portion and the second protrusion forming portion; and

a second protrusion-free portion disposed between the second protrusion forming portion and the third protrusion forming portion.

7. The horn of claim 1, wherein the protrusion has a truncated conical shape.

8. The weld head of claim 7, wherein sides of the bottom surface of the projection are parallel to sides of the welding surface.

9. The horn of claim 7, wherein the sides of the top surface of the projection are half or more of the sides of the bottom surface of the projection.

10. The horn of claim 9, wherein the edge of the top surface of the projection is 2/3 or greater than the edge of the bottom surface of the projection.

11. A welding device, comprising:

a horn including a plurality of protrusion forming parts each having a plurality of protrusions protruding from a welding surface and arranged in at least one row in a row, the plurality of protrusion forming parts respectively forming pattern forming parts on outermost electrode tabs among electrode tabs of a secondary battery, the non-protrusion part being disposed between the plurality of protrusion forming parts and in which the protrusions are not disposed to expose the welding surface to the outside, and a non-protrusion part forming a non-pattern part on the outermost electrode tabs, wherein the non-protrusion part has a width greater than a width of each of the protrusions;

an anvil facing the horn with the electrode tab therebetween to weld the electrode tab; and

a laser generating part generating a laser beam to emit the laser beam onto the non-pattern part when the electrode tab overlaps the electrode lead.

12. The welding device according to claim 11, wherein the projection forming portion includes a first projection forming portion and a second projection forming portion,

in the first protrusion forming portion, the plurality of protrusions are arranged in a plurality of rows in a row, and

in the second projection forming portion, the plurality of projections are arranged in parallel with the first projection forming portion.

13. The welding device according to claim 12, wherein the projection forming portion further includes a third projection forming portion in which the plurality of projections are arranged in parallel with the second projection forming portion.

14. The welding device of claim 13, wherein the projection-free portion comprises:

a first non-protrusion portion provided between the first protrusion forming portion and the second protrusion forming portion; and

a second protrusion-free portion disposed between the second protrusion forming portion and the third protrusion forming portion.

Technical Field

Cross Reference to Related Applications

This application claims the benefit of priority from korean patent application No. 10-2019-0007599, filed on 21/1/2019, which is hereby incorporated by reference in its entirety.

Technical Field

The present invention relates to a welding head and a welding apparatus, and more particularly, to a welding head and a welding apparatus capable of improving the welding strength of laser welding performed after ultrasonic welding.

Background

Generally, as types of secondary batteries, there are nickel cadmium batteries, nickel hydrogen batteries, lithium ion batteries, and lithium ion polymer batteries. Such secondary batteries are being applied to large-sized products requiring high output, such as electric vehicles or hybrid electric vehicles, Power storage devices storing generated surplus Power and renewable energy, and backup Power storage devices, and small-sized products, such as digital cameras, P-DVDs, MP3P, mobile phones, PDAs, Portable Game devices (Portable Game devices), Power tools (Power tools), and electric bicycles (E-bikes).

To manufacture a secondary battery, Electrode active material slurry is first applied to a positive Electrode current collector and a negative Electrode current collector to manufacture a positive Electrode and a negative Electrode, and the positive Electrode and the negative Electrode are stacked on both sides of a Separator to form an Electrode Assembly (Electrode Assembly) having a predetermined shape. The electrode assembly is then received in a battery case, an electrolyte is injected into the battery case, and the battery case is sealed.

The electrode assembly includes electrode tabs. Each of the electrode tabs protrudes outward from the electrode assembly to serve as a path through which electrons are supplied to be movable between the inside and the outside of the electrode assembly. The electrode tabs protrude from each of the plurality of electrodes so as to be connected to each other at the outside of the electrode assembly. Here, when connecting the plurality of electrode tabs to each other, ultrasonic welding using a Horn (Horn) and an Anvil (Anvil) may be used. The electrode assembly further includes an electrode lead. Each of the electrode leads is connected to the electrode tab to supply power generated inside the electrode assembly to the outside. Here, the electrode tab may be connected to the electrode lead using laser welding.

Fig. 1 is a schematic diagram illustrating a welding surface 311 of a welding head 31 according to the related art, and fig. 2 is a side view of the welding head 31 according to the related art.

When ultrasonically welding a plurality of electrode tabs to each other, first, a plurality of electrode tabs to be welded to each other are stacked and placed on a welding surface (not shown) of an Anvil (Anvil), and then pressure is applied to the electrode tabs through a welding surface 311 of a Horn (Horn) 31. Here, as shown in fig. 1 and 2, a projection forming portion 313 is provided on the welding surface 311 of the horn 31, and a plurality of sharply projecting projections 312 are arranged in series at certain intervals in the projection forming portion 313. When the bonding tool 31 applies pressure to the plurality of electrode tabs, a pattern recessed to correspond to the shape of the protrusions 312 is formed on the surface of the electrode tabs. Then, ultrasonic waves are applied to weld the plurality of electrode tabs to each other.

Further, after the ultrasonic welding is completed, the electrode tab and the electrode lead are overlapped with each other, thereby performing the laser welding. However, according to the related art, there is no gap or a very small gap between the plurality of protrusions 312. As a result, there are also no gaps or very small gaps between the patterns. However, when a laser beam is emitted after overlapping the electrode lead with the pattern forming part on which the pattern is provided, the energy of the laser beam is dispersed on the surface of the electrode tab due to the pattern. Therefore, there is a problem that the welding strength of the laser welding is deteriorated.

Disclosure of Invention

Technical problem

An object of the present invention is to provide a welding head and a welding device capable of improving the welding strength of laser welding performed after ultrasonic welding.

The object of the present invention is not limited to the aforementioned object but other objects not described herein will be clearly understood from the following description by those skilled in the art.

Technical scheme

To solve the problem, a bonding tool according to an embodiment of the present invention includes: a plurality of protrusion forming parts each having a plurality of protrusions protruding from the welding surface and arranged in at least one row in a row, the plurality of protrusion forming parts forming pattern forming parts on outermost electrode tabs among the electrode tabs of the secondary battery, respectively; and a no-protrusion part disposed between the plurality of protrusion forming parts and in which the protrusion is not disposed to expose the welding surface to the outside, the no-protrusion part forming a no-pattern part on the outermost electrode tab, wherein the no-protrusion part has a width greater than a width of each of the protrusions.

Further, the protrusion-free portion may have a width smaller than twice a width of the protrusion.

Further, the protrusion forming part may include a first protrusion forming part and a second protrusion forming part, and the plurality of protrusions may be arranged in a plurality of rows in a row in the first protrusion forming part.

Further, in the second protrusion forming portion, the plurality of protrusions may be arranged in parallel with the first protrusion forming portion.

Further, the protrusion forming part may further include a third protrusion forming part in which the plurality of protrusions are arranged in parallel with the second protrusion forming part.

Further, the protrusion-free portion may include: a first non-protrusion portion provided between the first protrusion forming portion and the second protrusion forming portion; and a second non-protrusion portion provided between the second protrusion forming portion and the third protrusion forming portion.

Further, the protrusion may have a truncated pyramid shape.

Further, an edge of the bottom surface of the protrusion may be parallel to an edge of the welding surface.

Further, the side of the top surface of the protrusion may be half or more of the side of the bottom surface of the protrusion.

Further, the edge of the top surface of the protrusion may be 2/3 or greater than the edge of the bottom surface of the protrusion.

In order to solve the problem, a welding apparatus according to an embodiment of the present invention includes: a horn including a plurality of protrusion forming parts each having a plurality of protrusions protruding from a welding surface and arranged in at least one row in a row, the plurality of protrusion forming parts respectively forming pattern forming parts on outermost electrode tabs among electrode tabs of a secondary battery, the non-protrusion part being disposed between the plurality of protrusion forming parts and in which the protrusions are not disposed to expose the welding surface to the outside, and a non-protrusion part forming a non-pattern part on the outermost electrode tabs, wherein the non-protrusion part has a width greater than a width of each of the protrusions; an anvil facing the horn with the electrode tab therebetween to weld the electrode tab; and a laser generating part generating a laser beam to emit the laser beam onto the non-pattern part when the electrode tab overlaps the electrode lead.

Further, the protrusion forming part may include a first protrusion forming part in which the plurality of protrusions may be arranged in a plurality of rows in a row, and a second protrusion forming part in which the plurality of protrusions are arranged in parallel with the first protrusion forming part.

Further, the protrusion forming part may further include a third protrusion forming part in which the plurality of protrusions are arranged in parallel with the second protrusion forming part.

Further, the protrusion-free portion may include: a first non-protrusion portion provided between the first protrusion forming portion and the second protrusion forming portion; and a second non-protrusion portion provided between the second protrusion forming portion and the third protrusion forming portion.

Other specific features of the invention are included in the detailed description and the accompanying drawings.

Advantageous effects

According to the embodiments of the present invention, at least the following effects can be obtained.

When ultrasonic welding is performed in a state where no projection portion is provided between the plurality of projection forming portions of the horn, the no-pattern portion and the plurality of pattern forming portions may be formed on the electrode tab. Since the laser welding is performed through the non-pattern portion, energy dispersion of the laser beam can be prevented, thereby improving welding strength of the laser welding.

The effects according to the present invention are not limited to the features exemplified above, and more various effects are included in the present application.

Drawings

Fig. 1 is a schematic diagram illustrating a welding surface of a welding head according to the related art.

Fig. 2 is a side view of a bonding tool according to the related art.

Fig. 3 is an assembly view of a secondary battery according to an embodiment of the present invention.

Fig. 4 is a schematic view illustrating a state in which ultrasonic welding is performed on an electrode tab by a welding apparatus according to an embodiment of the present invention.

Fig. 5 is a schematic diagram illustrating a welding surface of a weld head according to an embodiment of the present invention.

Fig. 6 is a side view of a weld head according to an embodiment of the invention.

FIG. 7 is a perspective view of a protrusion according to an embodiment of the present invention.

Fig. 8 is a schematic view illustrating a state in which laser welding is performed on an electrode tab and an electrode lead by a welding apparatus according to an embodiment of the present invention.

Fig. 9 is a schematic diagram illustrating a welding surface of a weld head according to another embodiment of the present invention.

Detailed Description

Advantages and features of the present invention and methods of accomplishing the same will be apparent from the following detailed description of exemplary embodiments thereof, which is to be read in connection with the accompanying drawings. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Furthermore, the invention is limited only by the scope of the claims. Like reference numerals refer to like elements throughout.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Unless expressly defined specifically, terms defined in commonly used dictionaries are not to be interpreted as having an ideal or excessive meaning.

In the present application, the terms are used only for explaining the embodiments, and do not limit the present invention. In this application, singular terms are intended to include the plural unless the context clearly indicates otherwise. The use of "comprising" and/or "comprising" in this application does not exclude the presence or addition of other elements than those mentioned.

Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings.

Fig. 3 is an assembly view of the secondary battery 1 according to an embodiment of the present invention.

The manufacturing process of the pouch-type secondary battery 1 according to an embodiment of the present invention is as follows. A slurry mixed with an electrode active material, a binder, and a plasticizer is first applied to a positive electrode current collector and a negative electrode current collector to manufacture a positive electrode and a negative electrode. The positive and negative electrodes are then stacked on both sides of the Separator to form the electrode assembly 10 having a predetermined shape. The electrode assembly 10 is then inserted into the battery case 13, an electrolyte is injected into the battery case 13, and the battery case is sealed.

The Electrode Assembly (Electrode Assembly)10 includes an Electrode Tab (Electrode Tab)11, as shown in fig. 3. The electrode tab 11 is connected to each of the positive and negative electrodes of the electrode assembly 10 and protrudes outward from the electrode assembly 10 to serve as a path through which electrons move between the inside and the outside of the electrode assembly 10. The current collector of the electrode assembly 10 is provided with a portion coated with the electrode active material, and an end portion, i.e., an uncoated portion not coated with the electrode active material. Here, the electrode tab 11 may be formed by cutting the uncoated portion or by connecting a separate conductive member to the uncoated portion via ultrasonic welding or the like. Although the electrode tabs 11 protrude from one side of the electrode assembly 10 in parallel with each other in the same direction as shown in fig. 3, the embodiment is not limited thereto, and thus the electrode tabs may protrude in different directions, respectively.

An Electrode Lead (Electrode Lead)12 is connected to the Electrode tab 11 of the Electrode assembly 10 by laser welding or the like. Further, a part of the electrode lead 12 is surrounded by the insulating part 14. The insulating part 14 is provided to be confined within the sealing part 134, and in the sealing part 134, the upper and lower pockets 131 and 132 of the battery case 13 are thermally bonded to bond the electrode lead 12 to the battery case 13. Further, the insulating part 14 prevents the electricity generated from the electrode assembly 10 from flowing to the battery case 13 through the electrode leads 12 and maintains the sealing of the battery case 13. Thus, the insulating portion 14 is made of a non-conductor having a non-conductivity in which electric power does not flow well. In general, although a relatively thin insulating tape that is easily attached to the electrode lead 12 is widely used as the insulating part 14, embodiments are not limited thereto, and thus various members may be used as long as they can insulate the electrode lead 12.

The electrode leads 12 may extend in the same direction or may extend in opposite directions depending on the formation positions of the cathode tab 111 and the anode tab 112. The cathode lead 121 and the anode lead 122 may be made of different materials from each other. That is, the positive electrode lead 121 may be made of the same aluminum (Al) material as the positive electrode plate, and the negative electrode lead 122 may be made of the same copper (Cu) or nickel (Ni) -coated copper material as the negative electrode plate. Further, a portion of the electrode lead 12 protruding outward from the battery case 13 serves as a terminal portion and is electrically connected to an external terminal.

In the pouch-type secondary battery 1 according to the embodiment of the present invention, the battery case 13 is a pouch made of a flexible material. Hereinafter, the battery case 13 will be described as a pouch. Is sealed after the battery case 13 accommodates the electrode assembly 10 such that a portion of the electrode lead 12, i.e., the terminal portion, is exposed. The battery case 13 includes an upper pocket 131 and a lower pocket 132, as shown in fig. 3. The lower pouch 132 is provided with an accommodation space 1331 accommodating the electrode assembly 10, and the upper pouch 131 covers the accommodation space 1331 from the upper side so that the electrode assembly 10 is not separated to the outside of the battery case 13. Here, as shown in fig. 3, an accommodation space 1331 is also provided in the upper pouch 131 to accommodate the electrode assembly 10 from the upper side. Although the upper and lower pockets 131 and 132 may be manufactured such that one sides thereof are connected to each other as shown in fig. 3, embodiments are not limited thereto and the pockets may be manufactured differently, for example, by being separately manufactured by being separated from each other.

When the electrode lead 12 is connected to the electrode tab 11 of the electrode assembly 10 and the insulating part 14 is disposed on a portion of the electrode lead 12, the electrode assembly 10 is received in the receiving space 1331 disposed in the lower pouch 132, and the upper pouch 131 covers the receiving space 1331 from the upper side. When the electrolyte is injected and then the sealing part 134 provided at the edge of each of the upper and lower pouches 131 and 132 is sealed, the secondary battery 1 is prepared.

Fig. 4 is a schematic diagram illustrating a state in which ultrasonic welding is performed on the electrode tab 11 by the welding apparatus 2 according to an embodiment of the present invention.

When ultrasonically welding the plurality of electrode tabs 11 to each other, first, the plurality of electrode tabs 11 to be welded are placed on the welding surface of the Anvil (Anvil)22, and then, as shown in fig. 4, pressure is applied to the electrode tabs 11 through the welding surface 211 (see fig. 5) of the Horn (Horn) 21. Here, a plurality of protrusions 212 (see fig. 5) are continuously arranged at certain intervals on the welding surface 211 of the horn 21 to provide protrusion forming portions 213 (see fig. 5). As the plurality of protrusions 212 are inserted into the plurality of electrode tabs 11, a pattern recessed in a shape corresponding to the protrusions 212 is formed on the outermost surface of the electrode tab 11. Then, when ultrasonic waves having a high frequency of about 20kHz are applied, the vibration energy of the horn 21 and the anvil 22 is converted into thermal energy due to friction, thereby performing welding.

Further, laser welding is performed on the electrode tab 11 and the electrode lead 12 provided after completion of the ultrasonic welding. Here, after the electrode tab 11 and the electrode lead 12 are overlapped with each other, a laser beam having a high energy density is emitted to the electrode tab 11 and the electrode lead 12. Accordingly, the portion between the electrode tab 11 and the electrode lead 12 is temporarily melted, and the melted portion is solidified again and then welded.

Fig. 5 is a schematic diagram illustrating a welding surface 211 of a welding head 21 according to an embodiment of the present invention.

When ultrasonic welding is performed by using the welding apparatus 2 according to an embodiment of the present invention, since the no-protrusion 214 is provided between the plurality of protrusion forming portions 213 of the horn 21, a plurality of pattern forming portions 1131 and 1132 (see fig. 8) and a no-pattern portion 1133 (see fig. 8) are formed on the electrode tab 11. Since the laser welding is performed through the non-pattern portion 1133, energy dispersion of the laser beam can be prevented, thereby improving welding strength of the laser welding.

To this end, the welding apparatus 2 according to an embodiment of the present invention includes: a soldering tip 21, the soldering tip 21 including a plurality of protrusion forming portions 213 and a non-protrusion portion 214, each of the plurality of protrusion forming portions 213 having a plurality of protrusions 212 protruding from a soldering surface 211 and arranged in at least one row in a row, the plurality of protrusion forming portions 213 forming pattern forming portions 1131 and 1132, respectively, on an electrode tab 11 of a secondary battery 1, the non-protrusion portion 214 being disposed between the plurality of protrusion forming portions 213 and in which the protrusion 212 is not disposed to expose the soldering surface 211 to the outside, the non-protrusion portion 214 forming a non-pattern portion 1133 on the electrode tab 11, wherein the non-protrusion portion 214 has a width W greater than a width D of each of the protrusion 212; an anvil 22 that faces the horn 21 with the electrode tab 11 positioned between the anvil 22 and the horn 21 to weld the electrode tab 11; and a laser generating part 23 (see fig. 8), the laser generating part 23 generating a laser beam to emit the laser beam onto the non-pattern part 1133 when the electrode tab 11 overlaps the electrode lead 12.

Further, the bonding tool 21 according to an embodiment of the present invention includes: a plurality of protrusion forming parts 213, each of the plurality of protrusion forming parts 213 having a plurality of protrusions 212 protruding from the welding surface 211 and arranged in at least one row in a row, the plurality of protrusion forming parts 213 forming pattern forming parts 1131 and 1132, respectively, on the electrode tab 11 of the secondary battery 1; and a protrusion-free portion 214, the protrusion-free portion 214 being disposed between the plurality of protrusion-forming portions 213 and in which the protrusions 212 are not disposed to expose the welding surface 211 to the outside, the protrusion-free portion 214 forming a non-pattern portion 1133 on the electrode tab 11, wherein the protrusion-free portion 214 has a width W greater than a width D of each of the protrusions 212.

As shown in fig. 5, the projection forming portion 213 is a portion in which a plurality of projections 212 projecting from the welding surface 211 of the welding head 21 are arranged in at least one row in a row. According to an embodiment of the present invention, the protrusion forming part 213 is provided in plurality and includes a first protrusion forming part 2131 and a second protrusion forming part 2132, as shown in fig. 5.

The first projection formation 2131 is provided at an upper portion of the horn 21 as shown in fig. 5, and the second projection formation 2132 is provided at a lower portion of the horn 21 as shown in fig. 5. Further, when ultrasonic welding is performed, the upper portion of the welding horn 21 is directed toward the electrode assembly 10, and the lower portion of the welding horn 21 is directed toward the side opposite to the electrode assembly 10. However, when the plurality of electrode tabs 11 overlap each other, a force with which the electrode tabs 11 are intended to be separated from each other increases as the electrode assembly 10 is approached. Thus, even in the ultrasonic welding region 113 where the ultrasonic welding is performed to the electrode tab 11, the welding strength must be relatively more increased in a region close to the electrode assembly 10. For this reason, according to an embodiment of the present invention, in the first protrusion forming portion 2131, the plurality of protrusions 212 may be arranged in a plurality of rows in a row. For example, as shown in fig. 5, in the first protrusion forming portion 2131, the plurality of protrusions 212 may be arranged in two rows in a row.

On the other hand, as it goes away from the electrode assembly 10, the force with which the electrode tabs 11 are intended to be separated from each other is reduced. Thus, in the second protrusion forming portion 2132, the protrusions may be arranged in a row only in one row. However, the embodiment is not limited thereto, and thus, in the second protrusion forming portion 2132, the plurality of protrusions 212 may also be arranged in a plurality of rows in a row.

The first protrusion forming part 2131 and the second protrusion forming part 2132 are provided at upper and lower portions, respectively, as shown in fig. 5. Here, when pressure is applied to the electrode tab 11 of the secondary battery 1 by the soldering terminal 21, pattern forming portions 1131 and 1132 in which the pattern is recessed into a shape corresponding to the protrusion forming portion 213 are provided at positions corresponding to the protrusion forming portion 213. Thus, in the ultrasonic welding region 113 of the electrode tab 11, the first pattern forming part 1131 in which the pattern is recessed into a shape corresponding to the first protrusion forming part 2131 is provided at a position corresponding to the first protrusion forming part 2131. Further, a second pattern formation portion 1132 in which a pattern is recessed in a shape corresponding to the second protrusion formation portion 2132 is provided at a position corresponding to the second protrusion formation portion 2132. As a result, the first pattern formation portion 1131 and the second pattern formation portion 1132 are provided at both ends of the ultrasonic welding region 113, respectively. Therefore, the minimum welding strength in the ultrasonic welding region 113 can be ensured.

In the first and second protrusion forming portions 2131 and 2132, a plurality of protrusions 212 may be arranged in parallel with each other. Thus, the first and second pattern forming parts 1131 and 1132 provided by the first and second protrusion forming parts 2131 and 2132, respectively, are also parallel to each other.

As shown in fig. 5, no projection 214 is provided between the plurality of projection forming parts 213 and no projection 212 is provided to expose the welding surface 211 to the outside. When pressure is applied to the electrode tab 11 of the secondary battery 1 by the bonding tool 21, the non-pattern portion 1133 is formed on the electrode tab 11. Subsequently, laser welding is performed after the electrode tab 11 and the electrode lead 12 are overlapped with each other. Here, according to an embodiment of the present invention, the electrode tab 11 is laser-welded through the non-pattern portion 1133. Therefore, energy dispersion of the laser beam can be prevented, thereby improving the welding strength of the laser welding.

When performing laser welding, the non-pattern portion 1133 must have a width large to some extent to avoid interference of the laser beam with the pattern. However, when the non-pattern portion 1133 has an excessively large width, the welding strength may be reduced. Thus, the width W of the projection-free portion 214 of the horn 21 for providing the non-pattern portion 1133 is larger than the width D of the projection 212 and smaller than twice the width D of the projection 212. For example, when the width D of the protrusion 212 is 1.2mm, the width of the protrusion-free portion 214 may be greater than 1.2mm and less than 2.4mm, preferably 1.8mm to 2.2 mm. Therefore, the welding strength can be ensured while avoiding interference of the laser beam with the pattern.

Fig. 6 is a side view of a weld head 21 according to an embodiment of the present invention.

According to an embodiment of the present invention, as shown in fig. 6, in the projection forming portion 213 of the horn 21, each projection 212 is provided to project from the welding surface 211 to one side. As the shape of the protrusion 212 is sharper, the protrusion is inserted deeper into the electrode tab 11. As a result, heat energy may be concentrated at the tip of the protrusion 212, thereby improving the welding strength. Therefore, according to the related art, the protrusion 212 has a conical shape or a polygonal pyramid shape, but the shape may damage the electrode tab 11.

However, according to an embodiment of the present invention, after ultrasonic welding is performed between the plurality of electrode tabs 11, laser welding is performed between the electrode tabs 11 and the electrode leads 12. Here, the welding strength between the plurality of electrode tabs 11 can be significantly improved. Thus, according to an embodiment of the present invention, as shown in fig. 6, the protrusion 212 has a truncated cone shape or a truncated polygonal pyramid shape in which the top surface T and the bottom surface B are parallel to each other, and thus damage of the electrode tab 11 can be reduced because the protrusion 212 is not sharp.

Fig. 7 is a perspective view of a protrusion 212 according to an embodiment of the present invention.

Since the protrusion 212 has a truncated cone shape or a truncated pyramid shape, the protrusion 212 has a top surface T and a bottom surface B, and the top surface T and the bottom surface B are parallel to each other. In order to ensure the minimum welding strength in the ultrasonic welding when the protrusion 212 is inserted into the electrode tab 11, the surface area of the top surface T of the protrusion 212 must be narrow to some extent. Meanwhile, in order to minimize the damage of the electrode tab 11, the surface area of the top surface T of the protrusion 212 must be wide to some extent.

Thus, if the protrusion 212 has a truncated cone shape as shown in fig. 7, it is preferable that the length of the side D of the top surface T is half or more of the length of the side D of the bottom surface B. In particular, it is more preferable that the length of the side D of the top surface T is 2/3 or more of the length of the side D of the bottom surface B. For example, when the length of the side D of the bottom surface B of the protrusion 212 is 1.2mm, the length of the side D of the top surface T may be 0.5mm or more, more preferably 0.8mm or more. Thus, damage to the electrode tab 11 can be reduced as much as possible. However, it is preferable that the length of the side D of the top surface T is 3/4 or less of the length of the side D of the bottom surface B. Thus, a minimum welding strength can be ensured.

As described above, on the welding surface 211 of the horn 21, the width W of the non-projecting portion 214 is larger than the width D of the projection 212. When the protrusion 212 has a truncated pyramid shape, the width D of the protrusion 212 is equal to the length of the side D of the bottom surface B. Thus, the width W of the non-protrusion 214 is greater than the length of the side D of the bottom surface B of the protrusion 212. However, the embodiment is not limited thereto, and thus the width W of the non-protrusion 214 may be greater than the diameter of the bottom surface B of the protrusion 212 because the width D of the protrusion 212 is the diameter of the bottom surface B when the protrusion 212 has a truncated conical shape.

Further, when the protrusions 312 have a polygonal pyramid shape, particularly, a regular polygonal pyramid according to the related art as shown in fig. 1, a certain angle is formed between each side on the bottom surface thereof and each side on the welding surface, thereby establishing a regular arrangement having a diamond pattern. However, according to an embodiment of the present invention, the non-protrusion portion 214 is provided between the first protrusion forming portion 2131 and the second protrusion forming portion 2132. Further, the non-projecting portion 214 must have a width large to some extent. Thus, if the protrusion 212 has a truncated cone shape as shown in fig. 7, the side D of the bottom surface B of the protrusion 212 is disposed in parallel with the side of the welding surface 211 as shown in fig. 5. That is, the protrusions 212 may be regularly arranged in a checkerboard pattern. Therefore, a larger width W without the protrusions 214 can be secured in the limited ultrasonic welding region 113 compared to the arrangement having the diamond pattern, thereby improving space efficiency.

Fig. 8 is a schematic diagram illustrating a state in which laser welding is performed on the electrode tab 11 and the electrode lead 12 by the welding apparatus 2 according to an embodiment of the present invention.

When the ultrasonic welding of the plurality of electrode tabs 11 is completed by using the horn 21 and the anvil 22, the laser welding is performed by using the laser generating section 23, as shown in fig. 8.

When the electrode lead 12 overlaps the electrode tab 11, which is ultrasonically welded, the laser generating part 23 generates a laser beam to emit the laser beam onto a portion where the electrode tab 11 and the electrode lead 12 overlap each other. In particular, according to an embodiment of the present invention, the laser generating part 23 emits a laser beam onto the non-pattern part 1133, as shown in fig. 8. Therefore, energy dispersion of the laser beam can be prevented, thereby improving the welding strength of the laser welding.

Fig. 9 is a schematic diagram illustrating a welding surface 211 of a welding head 21 according to another embodiment of the present invention.

According to an embodiment of the present invention, the protrusion forming portion 213 includes a first protrusion forming portion 2131 and a second protrusion forming portion 2132, and a no-protrusion portion 214 is provided between the first protrusion forming portion 2131 and the second protrusion forming portion 2132. If the size of the secondary battery 1 is increased, the surface area of the electrode tab 11 may become large. In this case, the surface area of the ultrasonic welding region 113 is also preferably increased to some extent. However, if only one projection-free portion 214 is provided, the surface area of the ultrasonic welding region 113 may not become large, or only the projection forming portion 213 may become excessively large to increase the surface area of the ultrasonic welding region 113.

Thus, according to another embodiment of the present invention, the protrusion forming portion 213a has three or more protrusion forming portions, and the protrusion-free portion 214a has two or more protrusion-free portions. For example, the protrusion forming part 213a may further include a third protrusion forming part 2133a, as shown in fig. 9. According to another embodiment of the present invention, since the protrusion forming part 213a has three or more protrusion forming parts, the number of pattern forming parts (not shown) may correspond to the number of protrusion forming parts.

In the third protrusion forming portion 2133a, the plurality of protrusions 212 are also arranged in at least one row in a row. Further, as shown in fig. 9, a first protrusion formation portion 2131a may be provided at an upper portion of the horn 21a, a second protrusion formation portion 2132a may be provided at a middle portion of the horn 21a, and a third protrusion formation portion 2133a may be provided at a lower portion of the horn 21 a. Thus, in the ultrasonic welding area 113, a third pattern forming portion (not shown) in which a pattern is recessed in a shape corresponding to the third protrusion forming portion 2133a may be further provided at a position corresponding to the third protrusion forming portion 2133 a.

As described above, in the first protrusion forming portion 2131a, the plurality of protrusions 212 may be arranged in parallel with the second protrusion forming portion 2132 a. Further, as shown in fig. 9, in the third protrusion forming portion 2133a, a plurality of protrusions 212 may also be arranged in parallel with the second protrusion forming portion 2132 a. Thus, the first to third pattern forming parts (not shown) may be disposed in parallel with each other.

The protrusion-free portion 214a may be disposed between the plurality of protrusion-forming portions 213 a. Thus, as shown in fig. 9, the protrusion-free portion 214a may include a first protrusion-free portion 2141a disposed between the first protrusion forming portion 2131a and the second protrusion forming portion 2132a, and a second protrusion-free portion 2142a disposed between the second protrusion forming portion 2132a and the third protrusion forming portion 2133 a. Thus, when pressure is applied to the electrode tab 11 of the secondary battery 1 by the soldering tip 21a, a first non-pattern portion (not shown) is formed on the electrode tab 11 by the first non-protrusion portion 2141a, and a second non-pattern portion (not shown) is formed on the electrode tab 11 by the second non-protrusion portion 2142 a. Further, when laser welding is subsequently performed after the electrode tab 11 and the electrode lead 12 are overlapped with each other, the laser welding is performed on the electrode tab 11 through a first non-pattern portion (not shown) and a second non-pattern portion (not shown). Thus, since the surface area on which the laser welding is performed is increased, the welding strength of the laser welding can be further improved.

Further, each of the width W1 of the first non-protrusion 2141a and the width W2 of the second non-protrusion 2142a may be greater than the width D of the protrusion 212 and less than twice the width D of the protrusion 212. Therefore, the welding strength can be ensured while avoiding interference of the laser beam with the pattern.

Those skilled in the art to which the invention pertains will appreciate that the invention may be embodied in other specific forms without changing the technical idea or essential features. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. The scope of the invention is defined by the appended claims rather than the foregoing description and the exemplary embodiments described therein. Various modifications made within the meaning and scope of claims and the equivalent concept of the claims are included in the scope of the present invention.