Electrode lead welding method

Abstract

The present invention relates to an electrode lead welding method for welding electrode leads of a cell assembly composed of a plurality of cells, comprising the steps of: preparing a cell stack in which a plurality of cells from which electrode leads are extruded are stacked; preparing a busbar frame having a lead connection portion including a pair of lead slits spaced apart at a predetermined interval; combining the cell stack and the busbar frame so that the electrode leads of the cell stack are inserted through the lead slits; bending the electrode leads that have passed through the lead slits of the lead connection portion so that they overlap each other; and welding the pair of overlapped electrode leads; wherein the lead connection portion includes an insertion groove between the pair of lead slits, and further comprising the step of inserting a welding prevention bar into the insertion groove prior to the welding step, wherein the welding prevention bar is inserted into the insertion groove at a predetermined interval from the rear surface of the electrode leads.

Description

Technology Field

[0001] The present invention relates to an electrode lead welding method for welding electrode leads of a cell assembly composed of a plurality of cells, and is characterized by providing a method of welding electrode leads using a welding prevention bar to prevent damage to the busbar frame by welding in order to electrically connect the electrode leads. Background Technology

[0003] FIG. 1 shows a cell assembly (1) comprising a cell stack (10) in which a plurality of cells (11) are stacked, each having electrode leads (12) extended on both sides.

[0004] The cell assembly (1) includes a cell stack (10) and a busbar frame (20) coupled to at least one side of the cell stack (10).

[0005] In the case of a conventional cell assembly (1), a bus bar (21) is applied for electrical connection between stacked cells (11), and a plurality of electrode leads (12) drawn from each of the plurality of cells (11) are positioned on the bus bar (21) and then welding is performed.

[0006] At this time, a plurality of busbars (21) are positioned at a predetermined interval on the busbar frame (20), and the welding is performed by a welding unit configured to move freely on the busbar frame (20).

[0007] The welding above can be performed toward the surface of the bent electrode lead (12) that is drawn out to the front of the busbar frame (20) as shown in FIG. 2.

[0008] The electrical connection between the electrode lead (12) and the bus bar (21) is completed by the above welding.

[0009] However, there may be a problem where the heat generated to perform the above welding is transferred to the busbar frame (20).

[0010] Since conventional busbar frames (20) are sometimes made of plastic material, the high temperature heat generated by the welding can have a very fatal effect. Prior art literature

[0012] Korean Patent Publication No. 10-2015-0038930 The problem to be solved

[0013] Accordingly, the present invention was devised to solve the above-mentioned problems and aims to provide a welding method that can prevent damage to the busbar frame when welding electrode leads.

[0014] In addition, the present invention aims to provide a welding method that prevents contact damage to the electrode lead by means of a welding prevention bar provided to prevent damage to the busbar frame during the welding process.

[0015] Other objects and advantages of the present invention may be understood from the following description and will become more clearly apparent from the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. means of solving the problem

[0017] According to the present invention, an electrode lead welding method is provided comprising: a step of preparing a cell stack in which a plurality of cells with electrode leads protruding are stacked; a step of preparing a busbar frame having a lead connection portion including a pair of lead slits spaced apart at a predetermined interval; a step of combining the cell stack and the busbar frame so that the electrode leads of the cell stack are inserted through the lead slits; a step of bending the electrode leads that have passed through the lead slits of the lead connection portion so that they overlap each other; and a step of welding the pair of overlapped electrode leads; wherein the lead connection portion includes an insertion groove between the pair of lead slits, and further comprising a step of inserting a welding prevention bar into the insertion groove prior to the welding step, wherein the welding prevention bar is inserted into the insertion groove at a predetermined interval from the rear surface of the electrode leads.

[0018] The above welding can be performed by laser welding.

[0019] The above insertion groove may be formed to extend along the length direction of the lead slit.

[0020] The above busbar frame may include a plurality of lead connection parts.

[0021] The above busbar frame includes a busbar mounted on the insertion groove so as to be in contact with the above-mentioned bent electrode lead, and in the welding step, the busbar and the electrode lead can be joined together by welding.

[0022] The busbar frame includes a busbar insertion portion that supports the rear surface of the busbar, and the busbar insertion portion may be located at the end of the insertion groove with respect to the length direction of the busbar frame and at the upper part of the insertion groove with respect to the thickness direction of the busbar frame.

[0023] At least one electrode lead can pass through the lead slit.

[0024] Each of the pair of lead slits included in the lead connection part can have electrode leads of different polarities pass through them.

[0025] The temperature of the heat generated by the above welding is 2000℃ or higher, and

[0026] The above-mentioned welding prevention bar may include a heat-resistant material capable of withstanding the heat generated in the welding.

[0027] The above welding prevention bars are provided in multiple numbers at the end of a prevention bar frame configured to be capable of reciprocating movement toward the busbar frame, and

[0028] Each of the above-mentioned welding prevention bars may be spaced apart at a predetermined distance from the end of the prevention bar frame.

[0029] Each of the above-mentioned welding prevention bars can be positioned at the end of the prevention bar frame corresponding to the spacing of the insertion groove of the bus bar frame.

[0030] The thickness length of the above-mentioned welding prevention bar is shorter than the depth of the above-mentioned insertion groove, and the above-mentioned welding prevention bar can be inserted so as to come into contact with the bottom part of the above-mentioned insertion groove.

[0031] The above-mentioned welding prevention bar can be inserted into the insertion groove during the step of preparing the busbar frame.

[0032] The above-mentioned welding prevention bar can be inserted into the insertion groove during the step of bending the electrode lead.

[0033] A plate-shaped welding filler that melts by welding may be interposed between the above-mentioned pair of electrode leads and the insertion groove of the busbar frame. Effects of the invention

[0035] According to the present invention, electrode leads and busbars, etc. can be welded without damaging the parts.

[0036] In addition, according to the present invention, contact damage to the electrode lead can be prevented by a welding prevention bar used to prevent damage to the busbar frame during welding. Brief explanation of the drawing

[0038] FIG. 1 is a perspective view of a conventional cell assembly. Figure 2 is an enlarged view of a part of the cell assembly of Figure 1. FIG. 3 shows a flowchart of an electrode lead welding method according to a first embodiment of the present invention. Figure 4 illustrates each step according to the flowchart of Figure 3 using a cell stack and a busbar frame. FIG. 5 is a perspective view of the busbar frame of the present invention. Figure 6 is a drawing of the busbar frame of Figure 5 cut in the horizontal direction. Figure 7 is a plan view of Figure 6 above. Figure 8 shows a busbar frame of Figure 7 with a welding prevention bar applied. Figure 9 is a front view of the busbar frame of Figure 8. Figure 10 is an enlarged view of a part of Figure 8 above. Figure 11 shows a welded anti-bar combined with an anti-bar frame. Figure 12 shows a part of a busbar frame with electrode leads bent. FIG. 13 is a cross-sectional view of a portion of the busbar frame of FIG. 12. Figure 14 shows a partial cross-section of a busbar frame with weld fillers applied. Figure 15 briefly illustrates the process of removing the welding prevention bar after welding. FIG. 16 shows a flowchart of an electrode lead welding method according to a second embodiment of the present invention. Figure 17 illustrates some of the steps according to the flowchart of Figure 16 using cell stacks and busbar frames. Specific details for implementing the invention

[0039] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, and should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0040] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0041] In addition, in describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the invention, such detailed description is omitted.

[0042] Since embodiments of the present invention are provided to more fully explain the invention to those skilled in the art, the shapes and sizes of the components in the drawings may be exaggerated, omitted, or schematically depicted for clearer explanation. Accordingly, the size or proportion of each component does not entirely reflect the actual size or proportion.

[0045] The present invention relates to an electrode lead welding method for welding electrode leads of a cell assembly composed of a plurality of cells, and is characterized by providing a method of welding electrode leads using a welding prevention bar to prevent damage to the busbar frame by welding in order to electrically connect the electrode leads.

[0046] FIGS. 3 to 15 relate to an electrode lead welding method according to a first embodiment of the present invention, and FIGS. 16 to 17 relate to an electrode lead welding method according to a second embodiment of the present invention.

[0047] Hereinafter, the electrode lead welding method of the present invention will be described with reference to each drawing.

[0049] (First embodiment)

[0050] FIG. 3 shows a flowchart of an electrode lead (111) welding method according to a first embodiment of the present invention. FIG. 4 shows each step according to the flowchart of FIG. 3 using a cell stack (100) and a busbar frame (200).

[0051] The electrode lead (111) welding method according to the first embodiment of the present invention is basically composed of a cell stack (100) preparation step (S1), a busbar frame (200) preparation step (S2), a joining step (S3), a bending step (S4), and a welding step (S5) as shown in FIG. 3, and an insertion step (S2') is further added to the basic configuration.

[0052] Below, each step will be explained with reference to FIGS. 3 and FIGS. 4.

[0054] Cell stack (100) preparation step (S1)

[0055] The step is to prepare a cell stack (100) in which a plurality of cells (110) with electrode leads (111) derived are stacked.

[0056] The cell (110) comprises an electrode assembly formed by stacking electrodes and a separator, an electrode lead (111) electrically connected to the electrode assembly, a case that encloses and seals the electrode assembly so that the electrode lead (111) is exposed to the outside, and an electrolyte filled together with the electrode assembly inside the case.

[0057] The cell (110) of the present invention includes a pair of electrode leads (111) having different polarities.

[0058] The cell stack (100) includes a plurality of cells (110) stacked in one direction so that electrode leads (111) can be arranged side by side at predetermined intervals.

[0060] Busbar frame (200) preparation stage (S2)

[0061] The step is to prepare a busbar frame (200) equipped with a lead connection portion (200p) including a pair of lead slits (230) spaced apart at a predetermined interval.

[0062] The above busbar frame (200) is provided with a busbar (210) that can be electrically connected to the electrode lead (111) of the cell stack (100).

[0063] The busbar frame (200) is combined with the cell stack (100) to fix the cell stack (100), and at the same time supports the rear surface of the electrode lead (111) so that the electrode lead (111) derived from the cell stack (100) can be fixed to the busbar (210).

[0064] FIG. 5 is a perspective view of the busbar frame (200) of the present invention, FIG. 6 is a horizontally cut view of the busbar frame (200) of FIG. 5, and FIG. 7 is a plan view of FIG. 6.

[0065] The lead connection portion (200p) is composed of a pair of lead slits (230) and an insertion groove (220) formed between the lead slits (230).

[0066] The above busbar frame (200) may have a plurality of lead connection parts (200p) formed according to the number of electrode leads (111) of the cell stack (100) being combined.

[0067] The lead slit (230) is opened so that the electrode lead (111) can pass through.

[0068] The lead slit (230) is formed in a shape through which the electrode lead (111) of the cell stack (100) combined with the busbar frame (200) can pass.

[0069] The lead slit (230) of the present invention is formed to extend along the short width direction of the busbar frame (200).

[0070] The above insertion groove (220) is formed in a shape that is recessed to a certain depth in the thickness direction of the busbar frame (200).

[0071] The above insertion groove (220) prevents the busbar frame (200) from coming into direct contact with the heat generated by welding, and may also serve as a passage for gases and byproducts generated by welding. In particular, in the present invention, the above insertion groove (220) becomes a zone into which a welding prevention bar (310), used to protect the surface of the busbar frame (200) from the heat of welding, is inserted.

[0072] The insertion groove (220) is formed to extend along the length direction of the lead slit (230).

[0073] The bus bar (210) is mounted on the insertion groove (220) so as to be electrically contacted with the electrode lead (111) penetrating the lead slit (230). That is, one bus bar (210) may be included in one lead connection part (200p).

[0074] The busbar frame (200) further includes a busbar (210) insertion portion formed in a recessed shape in the thickness direction of the busbar frame (200) so that the busbar (210) can be inserted.

[0075] The busbar (210) insertion portion may be formed at the end of the insertion groove (220). That is, the busbar (210) insertion portion is located at the end of the insertion groove (220) with respect to the short width direction of the busbar frame (200).

[0076] The busbar (210) insertion portion may be formed to overlap with the insertion groove (220). That is, the busbar (210) insertion portion may be located above the insertion groove (220) with respect to the thickness direction of the busbar frame (200).

[0077] The above bus bar (210) is inserted into the bus bar (210) insertion part so that the rear side can be supported.

[0079] Insertion step (S2')

[0080] The step is to insert a welding prevention bar (310) into the insertion groove (220) of the busbar frame (200).

[0081] The welding prevention bar (310) of the present invention can be inserted into the insertion groove (220) during the step of preparing the busbar frame (200). Accordingly, the step of preparing the busbar frame (200) of the present invention (S2) may include an insertion step (S2').

[0082] The above-mentioned welding prevention bar (310) is used to prevent the busbar frame (200) from being directly damaged by the high temperature heat generated by welding. That is, the welding prevention bar (310) is installed on the surface of the area to be protected from welding.

[0083] It is preferable that the above-mentioned welding prevention bar (310) comprises a heat-resistant material capable of withstanding the heat generated during welding. For example, the above-mentioned welding prevention bar may comprise carbon steel.

[0084] The electrode lead (111) welding method according to the first embodiment of the present invention involves attaching a welding prevention bar (310) to the busbar frame (200) in the step of preparing the busbar frame (200).

[0085] The above welding prevention bar (310) is inserted into the insertion groove (220) so that it can be attached and detached in various forms.

[0086] FIG. 8 shows a busbar frame (200) of FIG. 5 with a welding prevention bar (310) applied thereto, FIG. 9 is a front view of the busbar frame (200) of FIG. 8, and FIG. 10 is an enlarged view of a part of FIG. 8.

[0087] The above welding prevention bar (310) is composed of a bar-shaped prevention part (310a) that is extended so as to be inserted into the insertion groove (220), and a protrusion (310b) having a width longer than the width of the prevention part (310a) so as to catch at the entrance of the insertion groove (220) at the end of the prevention part (310a).

[0088] The above welding prevention bar (310) is coupled to the busbar frame (200) such that the prevention part (310a) is slidably inserted into the insertion part of the busbar frame (200) and the protrusion (310b) is caught in a protruding shape at the end of the busbar frame (200).

[0089] The above welding prevention bar (310) is inserted so as to come into contact with the bottom of the insertion groove (220).

[0090] The plurality of welding prevention bars (310) can be inserted independently into the required insertion grooves (220) as shown in FIGS. 8 and 9, or can be combined with one prevention bar frame (300) and inserted simultaneously into each insertion groove (220).

[0091] FIG. 11 shows a weld prevention bar (310) coupled to a prevention bar frame (300).

[0092] The above welding prevention bar (310) is provided in multiple numbers at the end of the prevention bar frame (300), which is configured to be able to move back and forth toward the bus bar frame (200). Specifically, the protrusion (310b) of the welding prevention bar (310) is coupled to the end of the prevention bar frame (300).

[0093] A plurality of welding prevention bars (310) coupled to the above prevention bar frame (300) are arranged so as to face in one direction on one side of the above prevention bar frame (300).

[0094] Each of the above welding prevention bars (310) is positioned at a predetermined distance from the end of the prevention bar frame (300) as shown in FIG. 11.

[0095] Each of the above-mentioned welding prevention bars (310) is located at the end of the prevention bar frame (300) corresponding to the spacing of the insertion groove (220) of the bus bar frame (200). That is, the position of each welding prevention bar (310) coupled to the prevention bar frame (300) is affected by the spacing of the insertion groove (220).

[0096] In the electrode lead (111) welding method of the present invention, it is preferable that the thickness length of the welding prevention bar (310) used is shorter than the depth of the insertion groove (220). At this time, if the thickness length of the welding prevention bar (310) is equal to the depth of the insertion groove (220) or is longer than the depth of the insertion groove (220), a problem may occur where the welding prevention bar (310) comes into contact with the electrode lead (111) when sliding it in the insertion groove (220).

[0098] Combination step (S3)

[0099] The step is to combine the cell stack (100) and the busbar frame (200) so that the electrode lead (111) of the cell stack (100) is inserted through the lead slit (230).

[0100] A plurality of electrode leads (111) protruding from one side of the cell stack (100) are inserted through a plurality of lead slits (230) formed in the busbar frame (200).

[0101] At least one electrode lead (111) passes through the above-mentioned lead slit (230).

[0102] Each of the pair of lead slits (230) included in the lead connection part (200p) has an electrode lead (111) of a different polarity passing through it.

[0104] Bending step (S4)

[0105] The step is to bend the electrode leads (111) that have passed through the lead slit (230) of the lead connection part (200p) so that they overlap each other.

[0106] FIG. 12 shows a part of a busbar frame (200) in which an electrode lead (111) is bent.

[0107] The electrode lead (111) that penetrates the lead slit (230) vertically is bent at an almost right angle and overlapped with each other so that it can be supported on the front of the busbar frame (200).

[0108] FIG. 13 is a cross-sectional view of a portion of the busbar frame (200) of FIG. 12.

[0109] The electrode lead (111) welding method of the present invention is characterized in that, as shown in FIG. 13, the welding prevention bar (310) is spaced apart from the rear surface of the electrode lead (111) by a predetermined distance so as not to come into contact with each other. That is, it is preferable that the rear surface of the bent electrode lead (111) is supported only by the busbar frame (200). At this time, the front surface of the busbar (210) is in contact with and connected to the rear surface of the bent electrode lead (111) as shown in FIG. 13.

[0110] A welding filler (400) that melts by welding may be interposed between the above-mentioned pair of electrode leads (111) and the insertion groove (220) of the busbar frame (200).

[0111] FIG. 14 shows a partial cross-section of a busbar frame (200) with a welding filler (400) applied.

[0112] The welding filler (400) may be plate-shaped, and both ends may be bent toward the busbar frame (200) as shown in FIG. 14.

[0113] Both ends of the bent weld filler (400) can be inserted into the lead slit (230) of the lead connection part (200p).

[0115] Welding step (S5)

[0116] This is the step of welding a pair of stacked electrode leads (111).

[0117] The above welding can be performed by laser welding.

[0118] The temperature of the heat generated at the welded area by the above welding is 2000℃ or higher.

[0119] The electrode leads (111) can be joined together by the above welding, or the electrode leads (111) and the bus bar (210) can be joined.

[0121] Removal step (S6)

[0122] The electrode lead (111) welding method of the present invention may further include a step of removing the welding prevention bar (310) inserted into the insertion groove (220).

[0123] Since the above welding prevention bar (310) has no additional use other than protecting the busbar frame (200) from welding, it is desirable to remove it to reduce the weight of the cell (110) assembly.

[0124] Accordingly, the inserted welding prevention bar (310), or the welding prevention bar (310) and the prevention bar frame (300) are removed by retracting from the bus bar frame (200).

[0125] Figure 15 briefly illustrates the process of removing the welding prevention bar (310) after welding.

[0126] The above welding prevention bar (310) is joined so as to be in close contact with the bottom of the insertion groove (220) to protect the bottom portion of the insertion groove (220) from the welding heat. At this time, the welding prevention bar (310) is not joined to the electrode lead (111) and welding filler (400), etc. by welding.

[0127] According to FIG. 15 above, after welding is finished, the welding prevention bar (310) is separated from and removed from the insertion groove (220).

[0129] (Second embodiment)

[0130] The step of inserting the welding prevention bar (310) may be included in the busbar frame (200) preparation step, or may be included in any step between the busbar frame (200) preparation step and the welding step.

[0131] FIG. 16 shows a flowchart of an electrode lead (111) welding method according to a second embodiment of the present invention. FIG. 17 shows some of the steps according to the flowchart of FIG. 16 using a cell stack (100) and a busbar frame (200).

[0132] The electrode lead (111) welding method according to the second embodiment of the present invention basically consists of a cell stack (100) preparation step (S1), a busbar frame (200) preparation step (S2), a joining step (S3), a bending step (S4), and a welding step (S5), and an insertion step (S4') is further added to the basic configuration.

[0134] The electrode lead (111) welding method according to the second embodiment of the present invention differs from the electrode lead (111) welding method according to the first embodiment in that the welding prevention bar (310) is not prepared by being inserted into the insertion groove (220) during the preparation stage of the busbar frame (200). That is, the welding prevention bar (310) is inserted in the stage immediately preceding each welding stage.

[0135] Referring to FIG. 16, the welding prevention bar (310) is inserted into the insertion groove (220) during the step of bending the electrode lead (111).

[0136] However, the thickness length of the welding prevention bar (310) is shorter than the depth of the insertion groove (220). Therefore, during the process of sliding the welding prevention bar (310) into the insertion groove (220), the welding prevention bar (310) and the bent electrode lead (111) do not come into contact.

[0138] The welding method of the electrode lead (111) according to the second embodiment of the present invention may further include the step of removing the welding prevention bar (310) inserted into the insertion groove (220), similar to the first embodiment.

[0139] Since the above welding prevention bar (310) has no additional use other than protecting the busbar frame (200) from welding, it is desirable to remove it to reduce the weight of the cell (110) assembly.

[0140] Accordingly, the inserted welding prevention bar (310), or the welding prevention bar (310) and the prevention bar frame (300) are removed by retracting from the bus bar frame (200).

[0141] The above welding prevention bar (310) is joined so as to be in close contact with the bottom of the insertion groove (220) to protect the bottom portion of the insertion groove (220) from the welding heat. At this time, the welding prevention bar (310) is not joined to the electrode lead (111) and welding filler (400), etc. by welding.

[0142] After the welding is finished, the welding prevention bar (310) is separated from and removed from the insertion groove (220).

[0144] The present invention has been described in more detail above through drawings and embodiments. However, the configurations described in the drawings or embodiments described in this specification are merely one embodiment of the present invention and do not represent all technical concepts of the present invention; therefore, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application. Explanation of the symbols

[0146] 1: (Prior art) Cell assembly 10: (Prior Art) Cell Stack 11: (Prior art) Cell 12: (Prior Art) Electrode Lead 20: (Prior Art) Busbar Frame 21: (Prior art) Busbar 100: Cell Stack 110: Cell 111: Electrode lead 200: Busbar frame 200p: Lead connector 210: Busbar 220: Insertion slot 230: Lead slit 300: Guard bar frame 310: Welding prevention bar 310a: Prevention part 310b: Protrusion 400: Welding filler S1: Cell stack preparation step S2: Busbar Frame Preparation Step S3: Combination step S4: Bending step S2', S4': Insertion step S5: Welding step S6: Removal step W: Welding

Claims

Claim 1 A method for welding electrode leads of a plurality of cells constituting a cell assembly, comprising the steps of: preparing a cell stack in which the plurality of cells are stacked; preparing a busbar frame including a lead connection portion having a pair of lead slits spaced apart from each other and an insertion groove provided between the pair of lead slits; joining the cell stack and the busbar frame so that the electrode leads of the plurality of cells are inserted into the pair of lead slits of the busbar frame; and bending the electrode leads so that the electrode leads penetrating the pair of lead slits of the busbar frame overlap each other and are supported on the front surface of the busbar frame. The electrode lead welding method comprises the step of welding the electrode leads that are stacked on top of each other; and further comprises the step of inserting a welding prevention bar into the insertion groove of the busbar frame prior to the step of welding the electrode leads, wherein the welding prevention bar is inserted into the insertion groove of the busbar frame such that it is spaced apart from the rear surfaces of the electrode leads supported on the front surface of the busbar frame, and in the step of welding the electrode leads, a space is formed between the welding prevention bar inserted into the insertion groove of the busbar frame and the rear surfaces of the electrode leads supported on the front surface of the busbar frame, and wherein the space is located between the rear surfaces of the electrode leads and the welding prevention bar in the thickness direction of the busbar frame. Claim 2 An electrode lead welding method according to claim 1, wherein the welding is performed by laser welding and further comprises the step of removing the welding prevention bar from the busbar frame. Claim 3 An electrode lead welding method according to claim 1, wherein the insertion groove of the busbar frame extends along the length direction of the pair of lead slits and has a shape recessed from the front of the busbar frame in the thickness direction of the busbar frame. Claim 4 In claim 1, the above-described busbar frame is an electrode lead welding method comprising a plurality of lead connection portions. Claim 5 An electrode lead welding method according to claim 1, wherein the busbar frame comprises a busbar mounted on the busbar frame so as to be in contact with the electrode leads stacked together, and the busbar and the electrode leads are joined together by welding during the welding step. Claim 6 In claim 5, the busbar frame includes a busbar insertion portion that supports the busbar, and the busbar insertion portion is located at one end of the insertion groove of the busbar frame, in an electrode lead welding method. Claim 7 An electrode lead welding method according to claim 1, wherein at least one of the electrode leads is inserted into each of the pair of lead slits of the busbar frame. Claim 8 An electrode lead welding method according to claim 1, wherein each of the pair of lead slits included in the lead connection part has an electrode lead of a different polarity passing through it. Claim 9 An electrode lead welding method according to claim 1, wherein the temperature of the heat generated by the welding is 2000℃ or higher, and the welding prevention bar comprises a heat-resistant material capable of withstanding the heat generated by the welding. Claim 10 In claim 1, the electrode lead welding method wherein the welding prevention bar is provided in a plurality of portions at the end of a prevention bar frame configured to be capable of reciprocating movement toward the bus bar frame. Claim 11 In claim 10, the above-mentioned busbar frame is an electrode lead welding method comprising a plurality of insertion grooves into which a plurality of welding prevention bars are inserted. Claim 12 In claim 1, an electrode lead welding method in which the thickness length of the welding prevention bar is shorter than the depth of the insertion groove of the busbar frame. Claim 13 In claim 1, the electrode lead welding method wherein the welding prevention bar is inserted into the insertion groove of the busbar frame during the step of preparing the busbar frame. Claim 14 In claim 1, the electrode lead welding method wherein the welding prevention bar is inserted into the insertion groove of the busbar frame during the step of bending the electrode leads. Claim 15 A method for welding electrode leads according to claim 1, wherein a plate-shaped welding filler that melts by welding is interposed between the electrode leads that are stacked on top of each other and the insertion groove of the busbar frame, and in the step of welding the electrode leads, a space is formed between the welding prevention bar inserted into the insertion groove of the busbar frame and the welding filler.

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