Welding apparatus, welding method, and electrode assembly

Abstract

A welding device according to an embodiment of the present invention can weld a plurality of electrode tabs of an electrode assembly. The welding device can include a pair of guides that collect the plurality of electrode tabs, and a welding unit that welds the plurality of electrode tabs collected by the pair of guides. The guides can include a lifting unit that lifts and lowers relative to the electrode tabs, and a rotating unit that rotates relative to the lifting unit while pressing the electrode tabs to pull the electrode tabs toward the electrode assembly.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0169085 filed on November 30, 2021, and all the contents disclosed in the document of the Korean patent application are incorporated herein by reference as part of this specification.

[0002] The present invention relates to a welding apparatus for welding a plurality of electrode tabs, a welding method using the welding apparatus, and an electrode assembly including a plurality of electrode tabs welded by the welding apparatus.

Background Art

[0003] Unlike primary batteries, secondary batteries can be recharged, and due to the possibility of miniaturization and large capacity, many research and developments have been carried out in recent years. As the technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source has been rapidly increasing.

[0004] Secondary batteries are classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries according to the shape of the battery case. In a secondary battery, an electrode assembly attached inside the battery case is a charge-dischargeable power generation element having a laminated structure of electrodes and a separator.

[0005] The electrode assembly can be generally classified into a jelly-roll type in which a separator is interposed between a sheet-like positive electrode and a negative electrode coated with an active material and wound, a stack type in which a plurality of positive electrodes and negative electrodes are sequentially laminated with a separator interposed therebetween, and a stack & folding type in which unit cells of the stack type are wound with a long separation film.

[0006] FIG. 1 is a diagram exemplarily showing a state in which electrode tabs of a general pouch-type secondary battery are bent.

[0007] Referring to Figure 1, a typical pouch-type secondary battery may include a pouch 10 that forms the external appearance, and an electrode assembly 20 housed in the pouch 10, in which multiple electrodes are stacked with separators in between.

[0008] The pouch 10 is formed by draw molding a pouch film, and the pouch film can be formed by laminating a metal layer, a first resin layer located on one side of the metal layer, and a second metal layer located on the other side of the metal layer. Therefore, the pouch 10 can have suitable strength and moldability, and the portion that houses the plurality of electrode tabs 30, which will be described later, can be easily deformed by external force.

[0009] The electrode assembly 20 may be provided with a plurality of electrode tabs 30 connected to the plurality of electrodes. The outer portions of the plurality of electrode tabs 30 can be welded to each other to form a welded portion 31, and electrode leads 40 protruding from the outside of the pouch 10 can be welded to the welded portion 31. With this configuration, the plurality of electrodes of the electrode assembly 20 can be electrically connected to an external terminal (not shown) via the plurality of electrode tabs 30 and electrode leads 40.

[0010] Conventionally, as shown in Figure 1, when the electrode lead 40 bends to one side (for example, the upper side) due to external impact or force, excessive tension is applied to the outermost electrode tab (for example, the lower outermost electrode tab) among the multiple electrode tabs 30 located on the opposite side from the bent lead, which can cause the outermost electrode tab to break or disconnect.

[0011] Furthermore, during the welding process of multiple electrode tabs 30, the electrode tabs 30 located further outward are welded in a more deformed state. Consequently, conventionally, during the welding process of multiple electrode tabs 30, excessive tension is applied to the outermost electrode tab, leading to the problem of the outermost electrode tab breaking or disconnecting. [Overview of the project] [Problems that the invention aims to solve]

[0012] One problem that the present invention aims to solve is to provide a welding apparatus and welding method that prevents excessive tension from being applied to the electrode tab.

[0013] Another problem that the present invention aims to solve is to provide an electrode assembly in which excessive tension is not applied to the electrode tabs. [Means for solving the problem]

[0014] A welding apparatus according to an embodiment of the present invention can weld a plurality of electrode tabs of an electrode assembly. The welding apparatus may include a pair of guides for gathering the plurality of electrode tabs, and a welding section for welding the plurality of electrode tabs gathered by the pair of guides. The guides may include a lifting section that moves up and down relative to the electrode tabs, and a rotating section that pushes the electrode tabs and rotates relative to the lifting section to pull the electrode tabs toward the electrode assembly.

[0015] The rotating portion may include a first surface facing the electrode assembly, a second surface located opposite the first surface, and an edge that connects the first and second surfaces, is rounded, and presses against the electrode tab.

[0016] The length of the second surface may be longer than the length of the first surface.

[0017] The distance between the first surface and the second surface can increase as they get closer to the edge.

[0018] The lifting mechanism may be formed to extend vertically and may consist of a pair of components spaced apart in the width direction of the electrode tab.

[0019] The guide may further include a slider that slides relative to the lifting section, and a link that connects the slider to the rotating section and links the operation of the slider to the rotating section.

[0020] The slider and the rotating part may be provided with a connecting part that hinges to the link.

[0021] When the slider moves toward the rotating part, the rotating part can be configured to pull the electrode tab toward the electrode assembly.

[0022] The guide may further include an elastic member that applies an elastic force to the slider in a direction away from the rotating part.

[0023] A sliding groove can be formed in the lifting section into which the end of the slider is inserted and into which the elastic member is arranged.

[0024] A welding method according to an embodiment of the present invention can weld a plurality of electrode tabs provided on an electrode assembly. The welding method may include the steps of: a pair of guides approaching each other to bring the plurality of electrode tabs together; the pair of guides pulling the electrode tabs toward the electrode assembly; and a welding portion welding the plurality of electrode tabs together.

[0025] The guide may include a lifting section that moves up and down relative to the electrode tab, and a rotating section that contacts the electrode tab and rotates relative to the lifting section. During the step of gathering the plurality of electrode tabs, the lifting section moves toward the electrode tab so that the rotating section presses the electrode tab, and during the step of pulling the electrode tab, the rotating section can rotate while pressing the electrode tab.

[0026] The guide may further include a slider that slides relative to the lifting section, and a link that connects the slider to the rotating section and links the operation of the slider to the rotating section. When the electrode tab is pulled, the slider can be moved toward the rotating section so that the rotating section rotates.

[0027] The electrode assembly according to an embodiment of the present invention can include a laminate in which a plurality of electrodes are laminated with a separator interposed therebetween, and a plurality of electrode tabs connected to the plurality of electrodes and welded to each other to form a welded portion. The outermost electrode tab among the plurality of electrode tabs can include a first section extending from the electrode and having an increasing distance from the laminate, and a second section extending from the first section and having a decreasing distance from the laminate.

[0028] The outermost electrode tab can further include a third section extending from the second section to the welded portion and having an increasing distance from the laminate.

[0029] At least a part of the plurality of electrode tabs is connected to the electrode and includes a flat portion formed flat, and the length of the flat portion may be longer as the electrode tab is located more outside.

[0030] The first section can include a flat portion formed flat and connected to the electrode, and a bent portion formed by bending and connecting the flat portion and the second section.

[0031] The outer end of the outermost electrode tab can have a step inside with respect to the outer ends of other electrode tabs.

[0032] The length from the point with the maximum curvature in the outermost electrode tab to the electrode may be longer than the length from the point with the maximum curvature in other electrode tabs to the electrode.

Advantage of the Invention

[0033] According to a preferred embodiment of the present invention, in a state where the rotating portion of the guide pulls the electrode tab, the welding portion welds the plurality of electrode tabs, so that the length between the laminate and the welded portion with respect to the electrode tab, particularly the outermost electrode tab, can be increased. Thereby, it is possible to prevent the outermost electrode tab from breaking due to the tension or vibration generated by the welding portion on the electrode tab.

[0034] Furthermore, in the completed electrode assembly, it is possible to prevent the electrode tabs, especially the outermost electrode tab, from breaking or disconnecting due to deformation such as bending of the leads. This improves the safety and reliability of the electrode assembly.

[0035] In addition, the present invention may include effects that can be easily predicted by those skilled in the art from the configuration of a preferred embodiment. [Brief explanation of the drawing]

[0036] The following drawings accompanying this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described later, serve to further illustrate the technical concept of the present invention. Therefore, the present invention should not be construed as being limited solely to the matters depicted in the drawings.

[0037] [Figure 1] This diagram illustrates a typical example of a bent electrode tab in a pouch-type rechargeable battery. [Figure 2] This is a perspective view of a welding apparatus according to one embodiment of the present invention. [Figure 3] This is a perspective view of the guide relating to one embodiment of the present invention. [Figure 4a] This is a diagram illustrating the operation of a guide relating to one embodiment of the present invention. [Figure 4b] This is a diagram illustrating the operation of a guide relating to one embodiment of the present invention. [Figure 4c] This is a diagram illustrating the operation of a guide relating to one embodiment of the present invention. [Figure 5] This is a flowchart of a welding method according to another embodiment of the present invention. [Figure 6] This is an enlarged side view of the electrode tab and its surroundings in an electrode assembly according to a comparative example. [Figure 7] This is an enlarged side view of the electrode tab and its surrounding area of ​​an electrode assembly according to another embodiment of the present invention. [Figure 8]This is an enlarged side view of the electrode tab and its surrounding area of ​​an electrode assembly according to another embodiment of the present invention. [Modes for carrying out the invention]

[0038] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. However, the present invention may be realized in various different forms and is not limited or restricted by the following embodiments.

[0039] In order to clearly explain the present invention, detailed descriptions of relevant prior art that are irrelevant to the description or that may unnecessarily obscure the essence of the invention have been omitted. In this specification, when assigning reference numerals to components in each drawing, the same or similar reference numerals are assigned to components that are the same or similar throughout the specification.

[0040] Furthermore, the terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather should be interpreted in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0041] Figure 2 is a perspective view of a welding apparatus according to one embodiment of the present invention, Figure 3 is a perspective view of a guide according to one embodiment of the present invention, and Figures 4a to 4c are diagrams illustrating the operation of the guide according to one embodiment of the present invention.

[0042] The welding apparatus 100 according to this embodiment can weld a plurality of electrode tabs 240 of an electrode assembly 200. The electrode assembly 200 may include a laminate 210 in which a plurality of electrodes are stacked with separators in between, and a plurality of electrode tabs 240 connected to the plurality of electrodes.

[0043] More specifically, the welding apparatus 100 may include a pair of guides 110 for gathering a plurality of electrode tabs 240, and welding sections 121, 122 for welding the plurality of electrode tabs 240 gathered by the pair of guides 110.

[0044] A pair of guides 110 can be positioned opposite each other with a plurality of electrode tabs 240 in between, and at least one of the pair of guides 110, preferably each guide 110, can be configured to move up and down relative to the electrode tabs 240. The pair of guides 110 can approach each other to grip the plurality of electrode tabs 240. The pair of guides 110 can gather the plurality of electrode tabs 240. The detailed configuration and operation of each guide 110 will be described in detail later.

[0045] The welded sections 121 and 122 can be formed by welding together a plurality of electrode tabs 240 that are brought together by a pair of guides 110 to form a welded section 245 (see Figure 4c). That is, the welded section 245 may be the portion where a plurality of electrode tabs 240 are welded to each other.

[0046] A pair of guides 110 can grip portions of the electrode assembly 200 in the electrode tab 240 that are relatively adjacent to the laminate 210, and welds 121 and 122 can weld portions of the electrode tab 240 that are relatively far from the laminate 210. The portion to be welded 245 can be separated from the laminate 210, and multiple electrode tabs 240 can extend so that they get closer to each other as they approach the portion to be welded 245.

[0047] The welds 121 and 122 can ultrasonically weld a plurality of electrode tabs 240 to each other. More specifically, the welds 121 and 122 may include an anvil 121 located on one side (e.g., the lower side) of the plurality of electrode tabs 240 and a horn 122 located on the other side (e.g., the upper side) of the plurality of electrode tabs 240. At least one of the anvil 121 and the horn 122 may be configured to move up and down relative to the electrode tabs 240.

[0048] One of the pair of guides 110 may be positioned adjacent to the anvil 121, and the other of the pair of guides 110 may be positioned adjacent to the horn 122.

[0049] With multiple electrode tabs 240 pressed between the anvil 121 and the horn 122, the horn 122 can vibrate at a high frequency, thereby welding the multiple electrode tabs 240 to each other. The anvil 121 can have a projection 121a that pushes the multiple electrode tabs 240 from one side, and the horn 122 can have a projection 122a that pushes the multiple electrode tabs 240 from the other side. Therefore, the welded portion 245 (see Figure 4c) formed on the multiple electrode tabs 240 can have multiple uneven shapes corresponding to the projections 121a and 121b.

[0050] On the other hand, the guide 110 may include a lifting section 111 that moves up and down relative to the electrode tab 240, and a rotating section 112 that rotates relative to the lifting section 111 while pressing the electrode tab 240. The guide 110 may further include a slider 113 that slides relative to the lifting section 111, and a link 114 that links the operation of the slider 113 and the rotating section 112.

[0051] It will be obvious to those skilled in the art that the welding apparatus 100 may be equipped with a lifting mechanism (not shown) for raising and lowering the lifting section 111.

[0052] The lifting section 111 can be formed as an extension in the vertical direction. The lifting section 111 may also be columnar in shape, extending substantially vertically. The lifting section 111 may be provided as a pair, spaced apart in the width direction of the electrode tab 240. The pair of lifting sections 111 can be arranged on both sides of the rotating section 112.

[0053] A slide groove 111a can be formed in the lifting section 111 to guide the slider 113. The slide groove 111a can extend in the longitudinal direction of the lifting section 111, i.e., in the vertical direction. The slide groove 111a can be formed on the inner surface of the lifting section 111. The slide grooves 111a of a pair of lifting sections 111 can face each other.

[0054] A connecting hole 111b can be formed in the lifting section 111, into which the rotating section 112 is rotatably connected. The connecting hole 111b can be formed closer to the electrode tab 240 than the slide groove 111a. The connecting holes 111b of a pair of lifting sections 111 can face each other.

[0055] The rotating part 112 rotates relative to the lifting part 111, allowing the electrode tab 240 to be pulled toward the electrode assembly 200, and more specifically toward the laminate 210. This increases the length of the electrode tab 240, particularly the outermost electrode tab, between the laminate 210 and the part to be welded 245. Consequently, the outermost electrode tab gains a length margin, which can prevent it from breaking due to external forces. This will be explained in more detail later.

[0056] The rotating part 112 may be a plate-like member that extends in the width direction of the electrode tab 240 and is positioned substantially vertically. The rotating part 112 can be rotatably connected to the lifting part 111. More specifically, the rotating part 112 may be provided with rotating shafts protruding from both sides, and these rotating shafts can be inserted into connecting holes 111b formed in the lifting part 111.

[0057] More specifically, the rotating part 112 may include a first surface 112a facing the electrode assembly 200, a second surface 112b located on the opposite side of the first surface 112a, and a rounded edge 112c connecting the first surface 112a and the second surface 112b.

[0058] The edge 112c can press against the electrode tab 240. Because the edge 112c is rounded, damage to the electrode tab 240 when pressed against the edge 112c can be prevented. As the rotating part 112 rotates, the edge 112c can pull the electrode tab 240 toward the electrode assembly 200, more specifically toward the laminate 210, while maintaining its pressure on the electrode tab 240. Needless to say, the edge 112c may be equipped with a material with high frictional force (e.g., rubber) to ensure that the edge 112c reliably pulls the electrode tab 240.

[0059] The rotation axis of the rotating part 112 can be located at the opposite end of the edge 112c. Therefore, even if the rotating part 112 rotates only slightly, the path that the edge 112c travels can be lengthened, allowing the edge 112c to sufficiently pull the electrode tab 240.

[0060] The length of the second surface 112b may be longer than the length of the first surface 112a. The edge 112c connecting the first surface 112a and the second surface 112b can be formed eccentrically toward the electrode assembly 200, or more specifically, toward the laminate 210. This ensures that contact between the edge 112c and the electrode tab 240 is reliably maintained as the rotating part 110 rotates and pulls the electrode tab 240 toward the laminate 210.

[0061] The first surface 112a and the second surface 112b can be formed at an angle to each other. More specifically, the distance between the first surface 112a and the second surface 112b can increase as they approach the edge 112c. This allows the length of the edge 112c in the round direction to be increased, and the contact area with the electrode tab 240 to be increased.

[0062] The slider 113 can slide relative to the lifting section 111. The slider 113 may be a plate-like member extending in the width direction of the electrode tab 240 and standing substantially vertically. The slider 113 can be positioned on the opposite side of the electrode tab 240 with the rotating section 112 in between. The slider 113 can slide in the length direction of the lifting section 111, i.e., vertically.

[0063] The slider 113 can slide along the slide groove 111a formed in the lifting section 111. Both ends of the slider 113 can be inserted into the slide groove 111a formed in the pair of lifting sections 111.

[0064] The welding apparatus 100 may be equipped with a pressurizing mechanism (not shown) that pressurizes the slider 113 toward the rotating part 112. The slider 113 can be moved toward the rotating part 112 by the pressurizing mechanism. The slider 113 can then be moved toward the rotating part 112 by an elastic member 115, which will be described later.

[0065] The link 114 may be substantially bar-shaped. The link 114 can connect the slider 113 and the rotating part 112. The link 114 can be rotatably connected to both the slider 113 and the rotating part 112.

[0066] More specifically, the slider 113 and the rotating part 112 may be provided with connecting parts 112d and 113d that hinge-connect to the link 114. The connecting part 112d on the rotating part 112 may be located at the opposite end of the edge 112c. The connecting part 113d on the slider 113 may be located at the end on the rotating part 112 side. The connecting part 112d on the rotating part 112 may hinge-connect to one end of the link 114, and the connecting part 113d on the slider 113 may hinge-connect to the other end of the link 114.

[0067] Link 114 can synchronize the movement of the slider 113 and the rotating part 112. Link 114 can convert the linear motion of the slider 113 into the rotational motion of the rotating part 112. When the slider 113 moves toward the rotating part 112, the rotating part 112 can be configured to pull the electrode tab 240 toward the electrode assembly 200. That is, when the slider 113 moves toward the rotating part 112, the rotating part 112 can rotate toward the electrode assembly 200, more specifically toward the laminate 210. Conversely, when the slider 113 moves toward the rotating part 112, the rotating part 112 can rotate toward the opposite side of the electrode assembly 200, more specifically toward the laminate 210.

[0068] The guide 110 may further include an elastic member 115 that applies an elastic force to the slider 113 in a direction away from the rotating part 112. For example, the elastic member 115 may be a spring. The elastic member 115 can be located inside the slide groove 111a of the lifting part 111. When the slider 113 is pressurized and moves toward the rotating part 112, the elastic member 115 can be compressed, and when the external force applied to the slider 113 is removed, the elastic force of the elastic member 115 can cause the slider 113 to move away from the rotating part 112.

[0069] The operation of the welding apparatus 100 according to this embodiment will be described below.

[0070] As shown in Figure 4a, the multiple electrode tabs 240 of the electrode assembly 200 can enter between a pair of guides 110 and between the anvil 121 and the horn 122.

[0071] Subsequently, as shown in Figure 4b, the pair of guides 110 can move closer to each other to collect the multiple electrode tabs 240. The multiple electrode tabs 240 are located on the rotating part 11 of the pair of guides 110. 2 It can be gripped between them. More specifically, the edge 112c of each rotating part 112 can press against the electrode tabs 240, especially the outermost electrode tabs.

[0072] Subsequently, as shown in Figure 4c, the pair of guides 110 can pull the electrode tabs 240 toward the laminate 210. More specifically, as the slider 113 moves toward the rotating part 112, the rotating part 112 rotates relative to the lifting part 111, and the edge 112c of the rotating part 112 can pull the outermost electrode tab toward the laminate 210 while maintaining contact with it. At this time, since the multiple electrode tabs 240 are in contact with each other, a frictional force acts between them, and not only the outermost electrode tab but also the other electrode tabs can be pulled toward the laminate 210.

[0073] In this state, the welds 121 and 122 can weld the electrode tabs 240 to form the welded portion 245. More specifically, at least one of the anvils 121 and horns 122 can move up and down to crimp and weld multiple electrode tabs 240.

[0074] As the rotating part 112 of the guide 110 pulls the electrode tab 240, the welding parts 121 and 122 weld multiple electrode tabs 240, allowing the length between the laminate 210 and the workpiece 245 to be welded to be increased with respect to the electrode tabs 240, especially the outermost electrode tab.

[0075] This prevents the electrode tabs 240, especially the outermost electrode tab, from fracturing due to the tension and vibration generated by the welds 121 and 122 on the electrode tabs 240.

[0076] Furthermore, it is possible to prevent the electrode tabs 240, particularly the outermost electrode tab, from breaking or disconnecting due to external forces on the completed electrode assembly 200. This improves the safety and reliability of the electrode assembly 200.

[0077] Figure 5 is a flowchart of a welding method according to another embodiment of the present invention.

[0078] The welding method using the welding apparatus 100 described above will be explained below as another embodiment of the present invention.

[0079] The welding method according to this embodiment can weld a plurality of electrode tabs 240 provided on an electrode assembly 200. More specifically, the welding method may include the steps of: bringing a pair of guides 110 closer together to gather a plurality of electrode tabs 240 (S20); pulling the electrode tabs 240 toward the electrode assembly 200 with the pair of guides 110 (S30); and causing the welding parts 121 and 122 to weld the plurality of electrode tabs 240 together (S40). The welding method may further include the step of stacking a plurality of electrodes 220 with a separator 230 (see Figure 7) in between to form a laminate 210 (S10) prior to the step of gathering a plurality of electrode tabs 240 (S20).

[0080] During the step of forming the laminate 210 (S10), multiple electrodes 220 (see Figure 7) can be stacked with a separator 230 in between. The method of stacking the multiple electrodes 220 is not limited. Each electrode 220 may include a surfaced portion coated with electrode active material and a plain portion not coated with electrode active material, and the plain portion can be processed into a suitable shape and act as an electrode tab 240.

[0081] During the step of gathering multiple electrode tabs 240 (S20), the lifting section 111 can move toward the electrode tabs 240 so that the rotating section 112 pushes the electrode tabs 240. More specifically, the lifting sections 111 of a pair of guides 110 can move closer to each other, and the multiple electrode tabs 240 can be gripped and gathered between the rotating sections 112 of the pair of guides 110.

[0082] During the step of pulling the electrode tab 240 (S30), the rotating part 112 can rotate while pressing against the electrode tab 240. At this time, the slider 113 can move toward the rotating part 112 so that the rotating part 112 rotates.

[0083] During the step (S40) of welding multiple electrode tabs 240 to each other, the welds 121 and 122 can weld the multiple electrode tabs 240 to form a welded portion 245. More specifically, at least one of the anvils 121 and horns 122 can move up and down to crimp and weld the multiple electrode tabs 240.

[0084] Although not shown in the drawings, electrode leads can be further welded to the welded portions 245 formed on multiple electrode tabs 240. The welding of the electrode leads to the welded portions 245 can be performed by laser welding.

[0085] Figure 6 is an enlarged side view of the electrode tab and its surroundings in an electrode assembly according to a comparative example, and Figures 7 and 8 are enlarged side views of the electrode tab and its surroundings in an electrode assembly according to yet another embodiment of the present invention.

[0086] More specifically, Figure 7 shows the state in which the rotating parts 112 of a pair of guides 110 have gathered multiple electrode tabs 240, and Figure 8 shows the state in which the rotating parts 112 of the pair of guides 110 shown in Figure 7 have rotated and pulled the multiple electrode tabs 240 toward the laminate 210.

[0087] Hereinafter, an electrode assembly 200 including a plurality of electrode tabs 240 welded by the welding apparatus 100 described above will be described as the present invention or another embodiment.

[0088] The electrode assembly 200 according to this embodiment may include a laminate 210 in which a plurality of electrodes 220 are stacked with a separator 230 in between, and a plurality of electrode tabs 240 connected to the plurality of electrodes 220 and welded to each other to form a welded portion 245 (see Figure 4c).

[0089] As described above, with the rotating part 112 of the guide 110 pulling the electrode tabs 240 toward the laminate 210, multiple electrode tabs 240 can be welded. Therefore, as shown in Figure 8, the outermost electrode tab 241 of the multiple electrode tabs 240 can be in an approximately S-shape or inverted S-shape. Figure 8 shows a state in which the rotating parts 112 of a pair of guides 110 grip multiple electrode tabs 240, but even if the pair of guides 110 separate from the multiple electrode tabs 240 after the formation of the welded portion 245 and the outermost electrode tab 241 deforms slightly, the outermost electrode tab 241 can maintain an approximately S-shape or inverted S-shape due to the welded portion 245.

[0090] More specifically, the outermost electrode tab 241 of the multiple electrode tabs 240 may include a first section 242 extending from the electrode 220, with increasing distance from the laminate 210, and a second section 243 extending from the first section 242, with decreasing distance from the laminate 210. The outermost electrode tab 241 may further include a third section 244 extending from the second section 243 to the workpiece 245, with increasing distance from the laminate 210.

[0091] The first section 242 may include a flat portion 242a that is connected to the electrode 220 and formed flat, and a curved portion 242b that is connected to the flat portion 242a and the second section 243 and formed by bending. The point where the outermost electrode tab 241 begins to bend can be separated from the laminate 210 by a predetermined distance, with the flat portion 242a in between. This has the advantage of preventing excessive stress concentration on the outermost electrode tab 241.

[0092] Not only the outermost electrode tab 241, but at least some of the multiple electrode tabs 240 may include a flat portion that is connected to the electrode 220 and formed flat. In this case, the further outward the electrode tab 240 is located, the longer the length of the flat portion can be formed. That is, the length of the flat portion 242a of the outermost electrode tab 241 may be longer than the length of the flat portions of the other electrode tabs 241.

[0093] The point P at which the curvature of the outermost electrode tab 241 is maximum can be located on the curved portion 242b. The length from the point P at which the curvature of the outermost electrode tab 241 is maximum to the electrode 220 may be longer than the length from the point P at which the curvature of the other electrode tabs 240 is maximum to the electrode 220. The distance d1 between the point P at which the curvature of the outermost electrode tab 241 is maximum and the laminate 210 may be greater than the distance d2 between the point P at which the curvature of the other electrode tabs 240 is maximum and the laminate 210.

[0094] In contrast, referring to Figure 6, the multiple electrode tabs 240' of the electrode assembly according to the comparative example can be welded together by a pair of guides 112' that do not include a rotating part. Therefore, the electrode tabs 240', especially the outermost electrode tab 241', do not have a section where they extend and the distance to the laminate 210 decreases. As a result, there is no margin in the length of the outermost electrode tab 241', and there is a risk that excessively high tension will be applied to the outermost electrode tab 241' due to external forces, etc., causing it to break. Also, since the outermost electrode tab 241' bends immediately at the point where it connects to the electrode 220, there is a risk that excessive stress concentration will occur and it will break.

[0095] On the other hand, referring again to Figure 8, the outer end of the outermost electrode tab 241 can have an inward step relative to the outer ends of the other electrode tabs 240. For example, the outer end of the outermost electrode tab 241 and the outer end of the central electrode tab can form a predetermined step S.

[0096] The outermost electrode tab 241 is pulled toward the laminate 210 by the rotating portion 112 of the pair of guides 110, and the frictional force between the multiple electrode tabs 240 causes the other electrode tabs 240 to also be pulled toward the laminate 210. Therefore, the further outward the electrode tab 240 is located, the more it is pulled toward the laminate 210, and for this reason, the outer end of the outermost electrode tab 241 can have an inward step relative to the outer ends of the other electrode tabs 240.

[0097] However, cutting or other processing may be performed to align the outer ends of multiple electrode tabs 240. In this case, a step does not need to be formed between the outer end of the outermost electrode tab 241 and the outer ends of the other electrode tabs 240.

[0098] The above description is merely illustrative of the technical concept of the present invention, and a person with ordinary skill in the art to which the present invention belongs can make various modifications and variations without departing from the essential characteristics of the present invention.

[0099] Therefore, the embodiments disclosed in this invention are for illustrative purposes only and not to limit the technical concept of the invention, and the scope of the technical concept of the invention is not limited by such embodiments.

[0100] The scope of protection of this invention shall be interpreted in accordance with the claims described below, and all technical ideas within an equivalent scope shall be interpreted as being included within the scope of rights of this invention. [Explanation of symbols]

[0101] 100: Welding equipment 110: Guide 111: Elevator 112: Rotating part 112a: First surface (of the rotating part) 112b: Second surface (of the rotating part) 112c: (The edge of the rotating part) 113: Slider 114: Link 115: Elastic member 121: Anvil (welded part) 122: Horn (welded part) 200: Electrode assembly 210: Laminate 220: Electrode 230: Separator 240: Electrode Tab 241: Outermost electrode tab 242: First section (of the outermost electrode tab) 242a: Flat section 242b: Curve 243: Second section (of the outermost electrode tab) 244: Third section (of the outermost electrode tab) 245: Welded part

Claims

1. A welding apparatus for welding multiple electrode tabs of an electrode assembly, A pair of guides for collecting the aforementioned multiple electrode tabs, A welding section for welding together multiple electrode tabs gathered by the aforementioned pair of guides, Includes, The aforementioned guide, A lifting mechanism that moves up and down relative to the electrode tab, A rotating part that presses the electrode tab and rotates relative to the lifting part to pull the electrode tab toward the electrode assembly, Welding equipment, including welding equipment.

2. The rotating part is, The first surface facing the electrode assembly, The second surface is located on the opposite side of the first surface, The welding apparatus according to claim 1, comprising: an edge that connects the first surface and the second surface, is formed in a rounded shape, and presses against the electrode tab.

3. The electrode assembly is constructed by stacking multiple electrodes with a separator in between. The welding apparatus according to claim 2, wherein the length of the second surface is longer than the length of the first surface with respect to the stacking direction of the electrodes.

4. The welding apparatus according to claim 2, wherein the distance between the first surface and the second surface increases as it approaches the edge.

5. The welding apparatus according to claim 1, wherein the lifting section is formed vertically and comprises a pair spaced apart in the width direction of the electrode tab.

6. The aforementioned guide, A slider that slides relative to the lifting mechanism, The welding apparatus according to claim 1, further comprising a link that connects the slider and the rotating part and links the operation of the slider and the rotating part.

7. The slider and the rotating part are: The welding apparatus according to claim 6, further comprising a connecting portion that hinges with the aforementioned link.

8. The welding apparatus according to claim 6, wherein when the slider moves toward the rotating part, the rotating part is configured to pull the electrode tab toward the electrode assembly.

9. The aforementioned guide, The welding apparatus according to claim 6, further comprising an elastic member that applies an elastic force to the slider in a direction away from the rotating part.

10. The welding apparatus according to claim 9, wherein the lifting section has a slide groove into which the end of the slider is inserted and in which the elastic member is arranged.

11. A welding method for welding multiple electrode tabs provided on an electrode assembly, The steps include: a pair of guides approaching each other to collect the plurality of electrode tabs; The step of the pair of guides pulling the electrode tab toward the electrode assembly, The weld includes the step of welding the plurality of electrode tabs together, The aforementioned guide, A lifting mechanism that moves up and down relative to the electrode tab, It includes a rotating part that contacts the electrode tab and rotates relative to the lifting part, During the step of collecting the plurality of electrode tabs, the lifting unit moves toward the electrode tabs so that the rotating unit presses against the electrode tabs. A welding method wherein, during the step of pulling the electrode tab, the rotating part rotates while pressing against the electrode tab.

12. The aforementioned guide, A slider that slides relative to the lifting mechanism, The invention further includes a link that connects the slider and the rotating part, and that links the operation of the slider and the rotating part, The welding method according to claim 11, wherein, during the step of pulling the electrode tab, the slider moves toward the rotating part so that the rotating part rotates.

13. A method for manufacturing an electrode assembly, comprising the welding method described in claim 11 or 12.

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