Electrode tab welding device and electrode tab welding method

Abstract

The present invention relates to an electrode tab welding device for welding electrode tabs protruding from an electrode assembly to each other, and includes a guide portion provided to converge the electrode tabs, and a welding portion provided to weld the electrode tabs converged by the guide portion at a predetermined welding region, and the guide portion may be provided to press the electrode tabs toward the electrode assembly while moving toward the electrode assembly so that a length from the electrode assembly to the welding region of at least a portion of the electrode tabs is increased before welding by the welding portion.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0167739, filed November 29, 2021, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an electrode tab welding device and an electrode tab welding method. [Background technology]

[0003] In general, secondary batteries are batteries that can be charged and discharged, unlike primary batteries that cannot be recharged, and are widely used in electronic devices such as mobile phones, laptops, and camcorders, as well as electric vehicles, etc. In particular, lithium secondary batteries have a larger capacity and higher energy density than nickel-cadmium batteries or nickel-metal hydride batteries, and therefore their use is rapidly increasing.

[0004] Depending on the shape of the battery case, secondary batteries can be divided into cylindrical batteries and prismatic batteries, in which the electrode assembly is housed in a cylindrical or prismatic metal case, and pouch batteries, in which the electrode assembly is housed in a pouch-shaped case made of an aluminum laminate sheet.

[0005] FIG. 1 illustrates an example of a pouch-type secondary battery. The pouch-type secondary battery 1 includes an electrode assembly 10 formed by alternately stacking electrodes and separators, and a pouch 20 that houses the electrode assembly 10. Electrode tabs 15 may be connected to the electrodes of the electrode assembly 10. The electrode tabs 15 may be welded to each other in predetermined areas and then connected to an electrode lead 17. The pouch 20 includes a recessed cup portion 21 for housing the electrode assembly 10. The pouch 20 may include one or two cup portions 21. FIG. 1 illustrates the pouch 20 including a left cup portion and a right cup portion. A peripheral portion 23 (terrace) for sealing is formed around the periphery of the cup portion 21.

[0006] However, when a tensile force is applied to the electrode tab 15 due to deformation of the periphery 23 of the pouch 20, the electrode tab 15 may gradually become taut and break. Alternatively, when a tensile force is applied to the electrode tab 15 due to expansion of the pouch 20, the electrode tab 15 may gradually become taut and break. Such breakage has been cited as a major cause of fires. In the case of pouch-type secondary batteries, the length of the periphery 23 has recently been reduced to increase energy density in response to demands for higher capacity and performance. However, this reduces the "length from the electrode assembly 10 to the welding point of the electrode tab 15" of the electrode tab 15, further increasing the possibility of breakage. Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide an electrode tab welding device and an electrode tab welding method that can prevent electrode tab breakage even in high-capacity, high-performance pouch-type secondary batteries by increasing the "length from the electrode assembly to the welding point of the electrode tab." [Means for solving the problem]

[0008] In one example, an electrode tab welding device for welding electrode tabs protruding from an electrode assembly to each other includes a guide portion configured to converge the electrode tabs, and a welding portion configured to weld the electrode tabs converged by the guide portion in a predetermined welding region, and the guide portion may be configured to press the electrode tabs toward the electrode assembly while moving toward the electrode assembly so that the length from the electrode assembly to the welding region of at least some of the electrode tabs increases before welding by the welding portion.

[0009] In another example, when the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground, the guide portion may include a first rod disposed on one of the upper and lower sides of the electrode tab and a second rod disposed on the other of the upper and lower sides of the electrode tab, and the first rod may be configured to move in a proximity direction toward the electrode assembly.

[0010] In yet another example, the first and second rods may be arranged to move relatively towards each other to adjust the distance between them in the vertical direction.

[0011] In yet another example, the first rod may be configured to move in the proximity direction while the first and second rods move relatively toward each other to press the electrode tab in the vertical direction.

[0012] In yet another example, the first rod may include a first rod body configured to move in the proximal direction, and a first rod roller disposed at one of an upper end and a lower end of the first rod body that faces the electrode tab, and configured to rotate while contacting the electrode tab located closest to the electrode tab when the first rod moves in the proximal direction.

[0013] In yet another example, the second rod may include a second rod body configured to move in the approaching direction in conjunction with the first rod body, and a second rod roller disposed at one of an upper end and a lower end of the second rod body that faces the electrode tab, and configured to rotate while contacting a nearest electrode tab among the electrode tabs while pressing the electrode tab in the vertical direction together with the first rod roller when moving in the approaching direction.

[0014] In yet another example, when the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground, the guide portion may include a first rod portion disposed on one of the upper and lower sides of the electrode tab, and a second rod portion disposed on the other of the upper and lower sides of the electrode tab, the first rod portion may include a first pressure rod for pressurizing the electrode tab in the vertical direction, and a first movable roller configured to move toward the electrode assembly and pull at least a portion of the electrode tab toward the electrode assembly, and the second rod portion may include a second pressure rod for moving relative to the first rod in the vertical direction and pressurizing the electrode tab in the vertical direction together with the first pressure rod.

[0015] In yet another example, the second rod portion may further include a second movable roller configured to move toward the electrode assembly in conjunction with the first movable roller when the electrode tab is pressed in the vertical direction by the first and second pressure rods.

[0016] In yet another example, a welding method for electrode tabs relates to a welding method for electrode tabs that welds electrode tabs protruding from an electrode assembly to each other, and may include: (a) a step of converging the electrode tabs by applying pressure to the electrode tabs from above and below when the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground; a step of applying pressure to the electrode tabs toward the electrode assembly in a state in which the electrode tabs are converged, thereby pulling at least a portion of the electrode tabs toward the electrode assembly; and a step of welding the electrode tabs in a predetermined welding area after the pulling.

[0017] In yet another example, the at least some of the electrode tabs may be welded in a state where the length from the electrode assembly to the welding region is increased by tension.

[0018] In yet another example, step (b) may be a step in which a first rod disposed on either the upper side or the lower side of the electrode tab moves toward the electrode assembly to press the at least a portion of the electrode tab toward the electrode assembly.

[0019] In yet another example, step (a) may be a step in which a second rod disposed on the other of the upper and lower sides of the electrode tab presses the electrode tab from above and below together with the first rod.

[0020] In yet another example, the first rod may include a first rod roller configured to move upward or downward in a proximity direction toward the electrode assembly and a separation direction away from the electrode assembly, and configured to rotate while contacting the electrode tab located closest to the first rod when moving in the proximity direction. [Effects of the Invention]

[0021] According to the present invention, by pulling at least a portion of the electrode tab toward the electrode assembly and then welding the electrode tab, it is possible to increase the length from the electrode assembly to the welding area of ​​at least a portion of the electrode tab. In the case of a battery manufactured according to the present invention, even if a tensile force is applied to the electrode tab due to deformation of the peripheral portion (terrace) of the pouch or due to expansion of the battery, the electrode tab can be prevented from breaking. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram illustrating an example of a pouch-type secondary battery. [Figure 2a] 10A to 10C are diagrams illustrating an exemplary process applicable to welding electrode tabs of a pouch-type secondary battery. [Figure 2b] 10A to 10C are diagrams illustrating an exemplary process applicable to welding electrode tabs of a pouch-type secondary battery. [Figure 2c]10A to 10C are diagrams illustrating an exemplary process applicable to welding electrode tabs of a pouch-type secondary battery. [Figure 2d] 10A to 10C are diagrams illustrating an exemplary process applicable to welding electrode tabs of a pouch-type secondary battery. [Figure 3] 1 is a cross-sectional view illustrating a portion of a battery module in which a plurality of pouch-type batteries are housed in a case. [Figure 4] 1 is a diagram illustrating an electrode tab welding device according to a first embodiment of the present invention; [Figure 5a] 5 is a diagram for explaining a method for welding an electrode tab using the welding device of FIG. 4. FIG. [Figure 5b] 5 is a diagram for explaining a method for welding an electrode tab using the welding device of FIG. 4. FIG. [Figure 5c] 5 is a diagram for explaining a method for welding an electrode tab using the welding device of FIG. 4. FIG. [Figure 5d] 5 is a diagram for explaining a method for welding an electrode tab using the welding device of FIG. 4. FIG. [Figure 5e] 5 is a diagram for explaining a method for welding an electrode tab using the welding device of FIG. 4. FIG. [Figure 6] 10A and 10B are diagrams illustrating a welding device for electrode tabs according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily understand and practice the present invention. However, the present invention may be embodied in various different forms and should not be construed as being limited to the following embodiments.

[0024] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may obscure the gist of the present invention will be omitted, and when referring to components in each drawing in this specification, the same or similar reference symbols will be used throughout the specification for the same or similar components.

[0025] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0026] First, a process for welding electrode tabs of a pouch-type secondary battery will be described with reference to Fig. 2. Fig. 2 is a view for explaining an exemplary process applicable to welding electrode tabs of a pouch-type secondary battery.

[0027] First, as shown in FIG. 2a, an electrode assembly 10 is prepared. The electrode assembly 10 may include an electrode 11 and a separator 13 stacked together. The electrode 11 includes a positive electrode and a negative electrode. An electrode tab 15 may be connected to the electrode 11. For convenience of explanation, only the negative electrode tab 15 connected to the negative electrode is illustrated in FIG. 2 and other figures. The positive electrode tab connected to the positive electrode may also be provided in the electrode assembly 10 so as to extend in a direction different from the extension direction of the negative electrode tab 15 and may be welded in the same manner as the negative electrode tab. Next, as shown in FIG. 2b, the electrode tabs 15 are converged. For example, the electrode tabs 15 may be converged by applying pressure to them using two rods 30A and 30B. Next, as shown in FIG. 2c, the electrode tabs 15 are welded via a welding portion 120.

[0028] Through this process, an electrode assembly 10 having electrode tabs 15 welded together at a predetermined welding area W can be manufactured as shown in Figure 2d. After connecting electrode leads 17 (see Figure 1) to the electrode tabs 15, the electrode assembly 10 can be housed in a pouch 20 (see Figure 1), thereby manufacturing a pouch-type battery 1.

[0029] A plurality of pouch-type batteries 1 can be housed in a single case C to be manufactured as a battery module, as shown in Fig. 3. Fig. 3 is a cross-sectional view illustrating a portion of a battery module in which a plurality of pouch-type batteries are housed in a case.

[0030] Here, during the manufacturing of the battery module, the periphery 23 of the pouch 20 may be bent. Deformation of the periphery 23 may induce bending of the electrode leads 17, which may cause tensile force on the electrode tabs 15 connected to the electrode leads 17 (see, for example, the electrode tab designated by reference numeral 15a in FIG. 3). This force may pull the electrode tabs 15 taut, causing breakage of the electrode tabs 15. This force may be greater in the outer electrode tabs 15a. The above-mentioned breakage problem may also occur when the battery expands.

[0031] The present invention, which will be described in detail below, is intended to solve the above-mentioned problem of broken wires.

[0032] Embodiment 1 4 is a diagram illustrating an electrode tab welding device according to a first embodiment of the present invention. The electrode tab welding device according to the first embodiment of the present invention relates to an apparatus for welding together electrode tabs 15 protruding from an electrode assembly 10, and as shown in FIG. 4, includes a guide portion 110 and a welding portion 120. For reference, hereinafter, it is assumed that the electrodes 11 and separators 13 of the electrode assembly 10 are stacked in a vertical direction perpendicular to the ground. However, this is merely an example, and the stacking direction of the electrodes 11 and separators 13 may vary depending on the direction from which the electrode assembly 10 is viewed.

[0033] The guide unit 110 may be provided to converge the electrode tabs 15. For example, the guide unit 110 may include a first rod 111 disposed on one of the upper and lower sides of the electrode tabs 15, and a second rod 112 disposed on the other of the upper and lower sides of the electrode tabs 15. Figure 4 illustrates an example of the first rod 111 disposed on the upper side and the second rod 112 disposed on the lower side. The first and second rods 111 and 112 may converge the electrode tabs 15 to a predetermined region G.

[0034] The first and second rods 111, 112 can move relative to each other in the vertical direction. For example, the second rod 112 can be stationary and only the first rod 111 can move toward the second rod 112, or the first rod 111 can be stationary and only the second rod 112 can move toward the first rod 111, or the first and second rods 111, 112 can move toward each other.

[0035] The distance between the first and second rods 111 and 112 can be adjusted by the relative movement of the first and second rods 111 and 112. When the distance between the first and second rods 111 and 112 decreases, the electrode tabs 15 can be pressed vertically by the first and second rods 111 and 112. This pressure can converge the electrode tabs 15 to a predetermined region G. In this process, the electrode tabs 15 can be bent toward the predetermined region G.

[0036] The welding unit 120 may be provided to weld the electrode tabs 15 converged by the guide unit 110 in a predetermined welding area W. For example, the welding unit 120 may include a horn and anvil for ultrasonic welding. Electrode leads 17 (see FIG. 1) for supplying electricity to the outside of the battery may be welded to the electrode tabs 15 welded by the welding unit 120.

[0037] In this embodiment, the guide unit 110 may pressurize the electrode tab 15 toward the electrode assembly 10 while moving toward the electrode assembly 10 before welding by the welding portion 120. By applying pressure in this manner, the guide unit 110 may increase the reference length L of all or part of the electrode tab 15. Here, the reference length L may be the "length from the electrode assembly 10 to the welding region W" of the electrode tab 15.

[0038] For example, when the electrode tab 15 is vertically pressed by the first and second rods 111 and 112 and the first and second rods 111 and 112 move toward the electrode assembly 10, at least a portion of the electrode tab 15 may be pulled toward the electrode assembly 10 by the pressure of the first and second rods 111 and 112, thereby increasing the "length L from the electrode assembly 10 to the welding area W" of the electrode tab 15. The remaining portion of the electrode tab 15 (e.g., the right portion of the welding area W in FIG. 4) may also be pulled toward the electrode assembly 10. For reference, while the second rod 112 supports the electrode tab 15, only the first rod 111 may move toward the electrode assembly 10. The guide unit 110 may apply pressure to the electrode tab 15 to an extent that allows the electrode tab 15 to be pulled.

[0039] When the electrode tabs 15 are welded in this tensioned state or after tension, the "length L from the electrode assembly 10 to the welding area W" of at least some of the electrode tabs 15 (e.g., the electrode tab designated by reference numeral 15b in FIG. 4) can be increased. This increase in length can prevent or delay breakage of the electrode tabs 15 due to the electrode tabs being pulled taut. This is because the electrode tabs 15 are stretched taut when pulled more than before the length increase. For reference, force applied to the electrode lead 17 (see FIG. 1) can be transmitted to the electrode tab 15 via the connection point between the electrode tab 15 and the electrode lead 17.

[0040] The pulling force of the electrode tabs 15 may be greater for electrode tabs (e.g., electrode tab 15b) located on the outer side (e.g., upper or lower side in FIG. 4) because the outermost electrode tabs 15 are subjected to greater pressure by the guide part 110.

[0041] The electrode tab welding device of this embodiment includes a guide portion 110 that is configured to pressurize the electrode tab 15 toward the electrode assembly 10 while moving toward the electrode assembly 10 so that the length L from the electrode assembly 10 to the welding area W of at least a portion of the electrode tab 15 increases before welding by the welding portion 120.Therefore, in the case of a battery manufactured by the electrode tab welding device of this embodiment, even if a tensile force is applied to the electrode tab 15 due to deformation of the peripheral portion 23 (terrace) of the pouch 20 or even if a tensile force is applied to the electrode tab 15 due to expansion of the battery, the electrode tab 15 will not be broken.

[0042] In this embodiment, the guide unit 110 can determine the degree of tension of the electrode tab 15 in consideration of the increase in length required to prevent disconnection. For example, in the case of a battery module in which the periphery of the pouch 20 is significantly deformed, the guide unit 110 can move further toward the electrode assembly 10. In this way, the guide unit 110 can adjust the distance it moves toward the electrode assembly 10 to adjust the degree of tension of the electrode tab 15, i.e., the increase in the reference length L.

[0043] Meanwhile, the first rod 111 may include a first rod body 111a configured to move in a direction toward the electrode assembly 10. Hereinafter, the direction toward the electrode assembly 10 (e.g., leftward in reference to FIG. 4) will be referred to as the approaching direction. The first rod body 111a may be a bar or block that rotatably supports a first rod roller 111b (described later). This also applies to a second rod body 112a (described later). For reference, the first rod 111 can move not only in the approaching direction but also in a receding direction, which is a direction away from the electrode assembly 10 (e.g., rightward in reference to FIG. 4). This also applies to the second rod 112.

[0044] The first rod 111 may include a first rod roller 111b disposed at the lower end of the first rod body 111a. When moving in the approaching direction, the first rod roller 111b may rotate while contacting the electrode tab 15 located closest to it (e.g., the electrode tab located at the top in FIG. 4). For example, the first rod roller 111b may move toward the electrode assembly 10 while contacting the uppermost electrode tab 15b, and may rotate due to friction with the electrode tab 15b. When the first rod 111 includes the first rod roller 111b, it is possible to apply pressure to the electrode tab 15 without damaging the electrode tab 15.

[0045] In this embodiment, the first rod 111 is disposed above the electrode tab 15, and therefore the first rod roller 111b may be disposed at the lower end of the first rod body 111a, which is the end facing the electrode tab 15, among the upper and lower ends. When the first rod is disposed below the electrode tab, the first rod roller may be disposed at the upper end of the first rod body.

[0046] The second rod 112 may also include a second rod body 112a configured to move in the proximal direction. The second rod body 112a may move in conjunction with the first rod body 111a. For example, when the first rod body 111a moves in the proximal direction while the electrode tab 15 is pressed by the first rod roller 111b and the second rod roller 112b (described later), the second rod body 112a may move in the proximal direction together with the first rod body 111a.

[0047] The second rod 112 may also include a second rod roller 112b disposed at one of the upper and lower ends of the second rod body 112a, whichever is closer to the electrode tab 15. Figure 4 illustrates the second rod roller 112b disposed at the upper end of the second rod body 112a. When moving in the approaching direction, the second rod roller 112b presses the electrode tab 15 vertically together with the first rod roller 111b, and can rotate while contacting the electrode tab 15 located closest to it (e.g., the electrode tab located at the bottom in Figure 4).

[0048] The welding process of the electrode tab 15 by the welding device of this embodiment will be described below with reference to Fig. 5. Fig. 5 is a diagram for explaining the method of welding the electrode tab by the welding device of Fig. 4.

[0049] First, as shown in Fig. 5a, the electrode assembly 10 is prepared. At this time, the electrode assembly 10 may be placed on a mounting unit 140. The mounting unit 140 may be a jig or a die on which the electrode assembly 10 may be placed.

[0050] Next, as shown in FIG. 5b, the electrode tabs 15 are converged. This can be achieved by operating the guide unit 110. For example, the first and second rods 111 and 112 can move toward each other to converge the electrode tabs 15 to a predetermined region G. Alternatively, the first rod 111 can pressurize the electrode tabs 15 from above to below while the second rod 112 supports the electrode tabs 15 from below, thereby converging the electrode tabs 15 to a predetermined region. In this way, the electrode tabs 15 can be converged by applying pressure from above and below.

[0051] Next, as shown in FIG. 5c, while the electrode tabs 15 are gathered, they are pressed toward the electrode assembly 10. This pressing may pull at least some of the electrode tabs 15 toward the electrode assembly 10. This may be achieved by operating the guide unit 110. For example, the first and second rod bodies 111a and 112a may move vertically to cause the first and second rod rollers 111b and 112b to press the electrode tabs 15 vertically. In this pressed state, the first and second rod bodies 111a and 112a may move horizontally to cause the first and second rod rollers 111b and 112b to press the electrode tabs 15 toward the electrode assembly 10. This pressing may pull at least some of the electrode tabs 15 (e.g., the electrode tab located at the top or bottom in FIG. 4) toward the electrode assembly 10.

[0052] Next, as shown in FIG. 5d, the electrode tab 15 is welded in the welding area W via the welding portion 120 while the electrode tab 15 is being pulled.

[0053] Through this process, the "length L (see FIG. 5d) from the electrode assembly 10 to the welding area W" can be increased in at least some of the electrode tabs 15, and the electrode tabs 15 can be welded together in this state. As a result, in the case of at least some of the electrode tabs 15 (e.g., the electrode tab designated by reference numeral 15c), as shown in FIG. 5e, the length from the electrode assembly 10 to the welding area W can be increased compared to when the pulling process is not performed. For reference, the closer the electrode tab 15 is to the guide portion 110, the greater the increase in length.

[0054] Embodiment 2 6 is a diagram illustrating an electrode tab welding apparatus according to a second embodiment of the present invention. The welding apparatus of the second embodiment differs from the welding apparatus of the first embodiment in the guide portion. The following description will focus on the guide portion of the second embodiment. For reference, the matters described in the first embodiment may be applied identically or similarly to the second embodiment.

[0055] The guide portion 210 may include a first rod portion 211 disposed on either the upper or lower side of the electrode tab 15. Figure 6 illustrates the first rod portion 211 disposed on the upper side of the electrode tab 15. The guide portion 210 may include a second rod portion 212 disposed on the other of the upper or lower side of the electrode tab 15. Figure 6 illustrates the second rod portion 212 disposed on the lower side of the electrode tab 15.

[0056] The first rod portion 211 may include a first pressure rod 211a for vertically pressing the electrode tab 15. FIG. 6 illustrates an example of a first pressure rod 211a that is disposed above the electrode tab 15 and descends downward to pressurize the electrode tab 15. The first pressure rod 211a may be implemented in various shapes that can pressurize the electrode tab 15. FIG. 6 illustrates an example of a rod-shaped first pressure rod 211a having a convex lower end. The first pressure rod 211a may descend to approach the electrode tab 15 or ascend to move away from the electrode tab 15. The content related to the first pressure rod 211a may be applied identically or similarly to the second pressure rod 212a described below.

[0057] The first rod portion 211 may include a first movable roller 211b configured to move toward the electrode assembly 10 and pull at least a portion of the electrode tab 15 toward the electrode assembly 10. The first movable roller 211b may be implemented in various shapes capable of pulling the electrode tab 15. FIG. 6 illustrates an example of a roller-shaped first movable roller 211b. The first movable roller 211b may move toward the electrode assembly 10 (e.g., leftward in FIG. 6) and away from the electrode assembly 10 (e.g., rightward in FIG. 6). The first movable roller 211b may move downward to move closer to the electrode tab 15 or upward to move away from the electrode tab 15. The description of the first movable roller 211b may be applied identically or similarly to the second movable roller 212b described below.

[0058] The second rod portion 212 may include a second pressure rod 212a that moves vertically relative to the first pressure rod 211a and applies vertical pressure to the electrode tabs 15 together with the first pressure rod 211a. The relative movement of the second pressure rod 212a can be described as the first pressure rod 211a being stationary and the second pressure rod 212a moving toward the first pressure rod 211a, the second pressure rod 212a being stationary and the first pressure rod 211a moving toward the second pressure rod 212a, or the first and second pressure rods 211a, 212a moving toward each other. The relative movement of the first and second pressure rods 211a, 212a may apply vertical pressure to the electrode tabs 15, thereby concentrating the electrode tabs 15 in a predetermined region.

[0059] The second rod portion 212 may include a second movable roller 212b that is arranged to move in conjunction with the first movable roller 211b toward the electrode assembly 10 when the electrode tab 15 is pressed in the vertical direction by the first and second pressure rods 211a and 212a. For example, when the first movable roller 211b moves, the second movable roller 212b may also move.

[0060] When the first and second pressure rods 211a, 212a move relative to each other to converge the electrode tabs 15 into a predetermined collection area, the first and second movable rollers 211b, 212b move together toward the electrode assembly 10, thereby increasing the "length from the electrode assembly 10 to the (planned) welding area" of at least some of the electrode tabs 15 (e.g., the uppermost or lowermost electrode tabs among the electrode tabs). After this increase in length, the welding unit 120 can weld the electrode tabs 15 in the welding area. For reference, the first and second movable rollers 211b, 212b can move from a state where they are vertically spaced apart from the electrode tabs 15 to a state where they approach the electrode tabs 15 and then move toward the electrode assembly 10. It is also possible for the guide unit 210 to include only the first movable roller 211b, and for the electrode tabs 15 to be pressed by only the first movable roller 211b.

[0061] The above description is merely an illustrative example of the technical concept of the present invention, and various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains without departing from the essential characteristics of the present invention.

[0062] Therefore, the embodiments disclosed in the present invention are for illustrative purposes only and are not intended to limit the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by such embodiments.

[0063] The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0064] 1. Pouch-type secondary battery 10 Electrode assembly 11 electrodes 13 Separator 15, 15a, 15b, 15c Electrode tabs 17 Electrode Lead 20 pouches 21 Cup section 23 Periphery 30A Rod 30B Rod 110 Guide section 111 First Rod 111a 1st rod body 111b First rod roller 112 Second Rod 112a 2nd rod body 112b Second rod roller 120 Welded Section 140 Placement section 210 Guide section 211 First rod section 211a First pressure rod 211b First moving roller 212 Second rod section 212a Second pressure rod 212b Second moving roller

Claims

1. An electrode tab welding device for welding electrode tabs protruding from an electrode assembly to each other, a guide portion configured to converge the electrode tabs by applying pressure in a vertical direction; a welding portion provided to weld the electrode tabs converged by the guide portion in a predetermined welding area, The guide portion is an electrode tab welding device configured to converge the electrode tabs by pressing them in the vertical direction so that the length from the electrode assembly to the welding area increases in at least a portion of the electrode tabs before welding by the weld portion, and to press the converged electrode tabs toward the electrode assembly while moving in a direction perpendicular to the vertical direction toward the electrode assembly.

2. The guide portion is When the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground, the electrode assembly includes a first rod disposed on one of the upper and lower sides of the electrode tab, and a second rod disposed on the other of the upper and lower sides of the electrode tab, The first rod is 2. The electrode tab welding device of claim 1, wherein the electrode tab welding device is adapted to move in a proximal direction toward the electrode assembly.

3. The first and second rods are 3. The electrode tab welding device according to claim 2, wherein the electrodes are adapted to move relative to each other to adjust the distance between them in the vertical direction.

4. The first rod is 4. The electrode tab welding device according to claim 3, wherein the first and second rods are arranged to move relative to each other and move in the approaching direction while pressing the electrode tab in the vertical direction.

5. The first rod is a first rod body configured to move in the approaching direction; 3. The electrode tab welding device according to claim 2, further comprising: a first rod roller disposed at one of the upper and lower ends of the first rod body that faces the electrode tab, the first rod roller being adapted to rotate while contacting the electrode tab located closest to the first rod body when the first rod body moves in the approaching direction.

6. The second rod is a second rod body provided to move in the approaching direction in conjunction with the first rod body; a second rod roller disposed at one of the upper and lower ends of the second rod body that faces the electrode tab, the second rod roller configured to rotate while contacting the electrode tab positioned closest to the electrode tab while pressing the electrode tab in the vertical direction together with the first rod roller when the second rod roller moves in the approaching direction.

7. An electrode tab welding device for welding electrode tabs protruding from an electrode assembly together, comprising: a guide portion provided to converge the electrode tabs; a welding portion provided to weld the electrode tab converged by the guide portion in a predetermined welding area, The guide portion is a welding section for welding the electrode tab to the welding region, the welding section being configured to press the electrode tab toward the electrode assembly while moving the electrode tab toward the electrode assembly so that the length from the electrode assembly to the welding region increases in at least a portion of the electrode tab; The guide portion is When the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground, the electrode assembly includes a first rod portion disposed on one of the upper and lower sides of the electrode tab, and a second rod portion disposed on the other of the upper and lower sides of the electrode tab, The first rod portion is a first pressure rod for applying pressure to the electrode tab in the vertical direction; and a first moving roller configured to move toward the electrode assembly and pull at least a portion of the electrode tab toward the electrode assembly, The second rod portion is a second pressure rod that moves relative to the first pressure rod in the vertical direction and presses the electrode tab in the vertical direction together with the first pressure rod;

8. The second rod portion is 8. The electrode tab welding device according to claim 7, further comprising a second movable roller configured to move toward the electrode assembly in conjunction with the first movable roller while the electrode tab is pressed in the vertical direction by the first and second pressure rods.

9. 1. A method for welding electrode tabs protruding from an electrode assembly together, comprising: (a) applying pressure to the electrode tabs from above and below in a vertical direction when the electrodes and separators of the electrode assembly are stacked in a vertical direction perpendicular to the ground, thereby converging the electrode tabs; (b) pressing the electrode tabs toward the electrode assembly while the electrode tabs are gathered, thereby pulling at least some of the electrode tabs toward the electrode assembly in a direction perpendicular to the vertical direction; (c) after the tensioning, welding the electrode tab at a predetermined welding area.

10. The at least some of the electrode tabs are The electrode tab welding method according to claim 9, wherein welding is performed in a state where the length from the electrode assembly to the welding area is increased by pulling.

11. The step (b) 10. The electrode tab welding method according to claim 9, further comprising the step of: moving a first rod disposed on one of an upper side and a lower side of the electrode tab toward the electrode assembly to press the at least a portion of the electrode tab toward the electrode assembly.

12. The step (a) The method for welding an electrode tab according to claim 11, further comprising the step of: applying pressure to the electrode tab from above and below together with the first rod using a second rod disposed on the other of the upper and lower sides of the electrode tab.

13. The first rod is 13. The electrode tab welding method according to claim 12, further comprising: a first rod roller adapted to move upward or downward in a proximity direction toward the electrode assembly and a separation direction away from the electrode assembly, and adapted to rotate while contacting a closest electrode tab among the electrode tabs when moving in the proximity direction.

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