Manufacturing Apparatus for Secondary Battery and Method for Manufacturing Secondary Battery

Abstract

The manufacturing apparatus for a secondary battery according to an embodiment of the present invention is a manufacturing apparatus for a secondary battery including a plurality of electrodes and separator membranes laminated alternately, an electrode tab provided at an end portion of the plurality of electrodes, and an electrode lead coupled to the electrode tab, and includes an upper fixing mold and a lower fixing mold that sandwich and fix the electrode lead, a lower molding mold disposed at a position spaced apart from an outer end portion side of the electrode lead from the lower fixing mold, and a plurality of upper molding molds disposed at a position spaced apart from an end portion side of the electrode lead from the upper fixing mold. The plurality of upper molding molds include a first upper molding mold that fixes the electrode lead and a second upper molding mold that forms first and second bending portions. The first upper molding mold and the second upper molding mold are separated from each other and are sequentially disposed in a direction from the electrode assembly toward an end portion of the electrode lead.

Description

Technical Field

[0001] Cross-reference to related application(s) This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0088171 filed on July 18, 2022, and all the contents disclosed in the document of the Korean patent application are incorporated herein by reference in their entirety.

[0002] The present invention relates to an apparatus for manufacturing a secondary battery and a method for manufacturing a secondary battery, and more particularly, to an apparatus for manufacturing a secondary battery and a method for manufacturing a secondary battery that can reduce tensile stress applied to a coupling portion between an electrode lead and an electrode tab and prevent disconnection.

Background Art

[0003] Due to the rapid increase in the use of fossil fuels, there is an increasing demand for the use of alternative energy and clean energy. As part of this, the fields of power generation and power storage using electrochemistry are the most actively studied.

[0004] Currently, a typical example of an electrochemical device using such electrochemical energy is a secondary battery, and its usage area is increasingly expanding.

[0005] Recently, as the technology development and demand for portable devices such as portable computers, mobile phones, and cameras have increased, the demand for secondary batteries as an energy source has increased rapidly. Among them, many studies have been conducted on lithium secondary batteries that exhibit high energy density, operating potential, long cycle life, and low self-discharge rate, and they have also been commercialized and widely used.

[0006] In addition, as interest in environmental issues grows, research on electric vehicles, hybrid electric vehicles, etc., which can replace vehicles using fossil fuels such as gasoline vehicles and diesel vehicles, which are one of the main causes of air pollution, is being actively pursued. As power sources for such electric vehicles, hybrid electric vehicles, etc., nickel-metal hydride secondary batteries are mainly used, but research using lithium secondary batteries with high energy density and discharge voltage is actively underway and some are in the commercialization stage.

[0007] Such a lithium secondary battery is manufactured by coating a current collector with a positive or negative electrode active material, a binder, and a conductive agent in the form of a slurry and drying to form an electrode mixture layer to produce a positive electrode and a negative electrode, interposing a separator between the positive electrode and the negative electrode, and incorporating the laminated electrode assembly together with an electrolytic solution into a battery case. The electrode tabs extending from each battery of the electrode assembly incorporated in the battery case are collected and welded so as to be connected to an electrode lead. It is electrically connected to an external device by an electrode lead.

[0008] FIG. 1 and FIG. 2 are diagrams showing, as an example, a manufacturing apparatus for a secondary battery according to the prior art.

[0009] FIG. 1 is a diagram showing a state before bending and forming of an electrode lead in a manufacturing apparatus for a secondary battery according to the prior art, and FIG. 2 is a diagram showing a state after bending and forming of an electrode lead in a manufacturing apparatus for a secondary battery according to the prior art.

[0010] Referring to FIGS. 1 and 2, an electrode assembly 1 is formed by laminating a plurality of positive electrodes and negative electrodes with a separator interposed therebetween, and a secondary battery can be manufactured by housing such an electrode assembly 1 in a battery case 2. The electrode tabs 3 connected to each electrode included in the electrode assembly 1 are collected and welded as shown in the drawing and then connected to an electrode lead 4. A lead film 5 surrounding the electrode lead 4 may be positioned on the electrode lead 4 so as to enhance the sealing force with the battery case 2.

[0011] The electrode lead 4 can be electrically connected to an external device and can be appropriately formed into various forms according to the environment in such a connected state. A process of bending the electrode lead 4 into an appropriate form is required for the forming of the electrode lead 4. For such bending, as shown in FIGS. 1 and 2, upper and lower molds 30, 40 having the shape of the electrode lead 4 to be obtained are prepared, and with the joining portion of the battery case 2 and the electrode lead 4 fixed by the upper fixed mold 10 and the lower fixed mold 20, the upper and lower molds 30, 40 are joined to press the electrode lead 4. At this time, due to the force for pressing the electrode lead 4, a strong tensile force is particularly applied to the joining portion A between the electrode lead 4 and the electrode tab 3, which may cause problems such as disconnection of the joining portion A between the electrode tab 3 and the electrode lead 4. Summary of the Invention Problems to be Solved by the Invention

[0012] The problem to be solved by the present invention is to provide a manufacturing apparatus for a secondary battery and a manufacturing method for a secondary battery that can prevent disconnection from occurring at the joining portion between the electrode tab and the electrode lead due to the tensile force generated in the forming process of the electrode lead.

[0013] However, the problems to be solved by the embodiments of the present invention are not limited to the foregoing problems and can be variously extended within the scope of the technical idea included in the present invention. Means for Solving the Problems

[0014] The manufacturing apparatus for a secondary battery according to an embodiment of the present invention is a manufacturing apparatus for a secondary battery including a plurality of electrodes and separation membranes laminated alternately, an electrode tab provided at an end portion of the plurality of electrodes, and an electrode lead coupled to the electrode tab, including an upper fixing die and a lower fixing die that sandwich and fix the electrode lead, a lower molding die disposed at a position spaced apart from an outer end portion side of the electrode lead from the lower fixing die, and a plurality of upper molding dies disposed at a position spaced apart from an end portion side of the electrode lead from the upper fixing die. The plurality of upper molding dies include a first upper molding die that fixes the electrode lead and a second upper molding die that forms first and second bending portions. The first upper molding die and the second upper molding die are separated from each other and are sequentially arranged in a direction from the electrode assembly toward an end portion of the electrode lead.

[0015] The first upper molding die and the second upper molding die are movable independently of each other.

[0016] The manufacturing apparatus may further include a third upper molding die that is disposed adjacent to the second upper molding die in a direction from the electrode assembly toward an end portion of the electrode lead and forms a third bending portion.

[0017] The third upper molding die is separated from the first upper molding die and the second upper molding die and is movable independently.

[0018] Only the electrode lead may be disposed between the first upper molding die and the lower molding die.

[0019] A method for manufacturing a secondary battery according to another embodiment of the present invention is a method for manufacturing a secondary battery including a plurality of electrodes and separator films alternately laminated, an electrode tab provided at an end of the plurality of electrodes, and an electrode lead coupled to the electrode tab. The method includes, between an upper fixed mold and a lower fixed mold, a step of primarily fixing the electrode lead at a first fixing portion, a step of secondarily fixing the electrode lead by lowering a first upper forming mold toward a lower forming mold at a second fixing portion spaced apart from an outer end portion side of the electrode lead from the first fixing portion, and a step of forming a first bending portion and a second bending portion on the electrode lead by lowering a second upper forming mold positioned adjacent to the outer end portion side of the electrode lead toward the lower forming mold.

[0020] In a state where the second upper forming mold is lowered, the method may include a step of forming a third bending portion on the electrode lead by lowering a third upper forming mold positioned on the outer end portion side of the electrode lead from the second upper forming mold toward the lower forming mold.

[0021] At the second fixing portion, only the electrode lead may be disposed between the first upper forming mold and the lower fixed mold.

[0022] At the first fixing portion, the electrode lead, a lead film surrounding the electrode lead, and a battery case of the secondary battery may be disposed between the upper fixed mold and the lower fixed mold.

[0023] At the first fixing portion and the second fixing portion, the same magnitude of force may be applied to press the electrode lead against the upper fixed mold and the first upper forming mold.

[0024] At the second fixing portion, the force for pressing the electrode lead by the first upper forming mold may be even greater than the force for pressing the electrode lead by the upper fixed mold at the first fixing portion.

Advantages of the Invention

[0025] According to an embodiment of the present invention, it is possible to minimize the generation of tensile force in the electrode lead forming process and prevent disconnection from occurring at the joint between the electrode tab and the electrode lead.

[0026] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned should be clearly understood by those skilled in the art from the description of the claims.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0028] Hereinafter, with reference to the accompanying drawings, various embodiments of the present invention will be described in detail so that those having ordinary knowledge in the technical field to which the present invention pertains can easily implement them. The present invention can be embodied in various different forms and is not limited to the embodiments described here.

[0029] To clearly explain the present invention, parts not related to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

[0030] In addition, the sizes and thicknesses of the respective components shown in the drawings are arbitrarily shown for convenience of explanation, and thus the present invention is not necessarily limited to those shown. The thickness is enlarged to clearly show various layers and regions in the drawings. And for convenience of explanation in the drawings, the thicknesses of some layers and regions are exaggerated.

[0031] Also, when a part such as a layer, film, region, or plate is said to be "on" or "above" another part, this includes not only the case where it is directly above the other part but also the case where there are other parts in between. Conversely, when a part is said to be "directly above" another part, it means that there are no other parts in between. Also, being "on" or "above" a reference part means being located above or below the reference part, and does not necessarily mean being located "on" or "above" in the direction opposite to gravity.

[0032] Also, throughout the specification, when a part "includes" a certain component, this means that, unless otherwise stated to the contrary, it does not exclude other components and may further include other components.

[0033] Also, throughout the specification, when "on a plane" is mentioned, this means when looking at the target part from above, and when "in a cross-section" is mentioned, this means when looking at a cross-section cut perpendicularly to the target part from the side.

[0034] Hereinafter, a manufacturing apparatus for a secondary battery according to an embodiment of the present invention will be described with reference to FIGS. 3 and 4.

[0035] The secondary battery comprises an electrode assembly 1 housed in a battery case 2 and includes an electrode lead 4 drawn out to the outside of the battery case 2 for electrical connection to the outside. The electrode assembly 1 is a power generation element capable of charge and discharge, and has a structure in which a positive electrode and a negative electrode are alternately laminated with a separator interposed therebetween. Electrode tabs 3 are formed to extend from the ends of the electrodes included in the electrode assembly 1, respectively. The electrode tabs 3 can be collected and welded at one point, and the collected electrode tabs 3 and the electrode lead 4 can be joined by means such as welding.

[0036] One end of the electrode lead 4 is electrically connected to the electrode tab 3, extends through the sealing portion of the battery case 2, and the opposite end protrudes outside the battery case 2. The lead film 5 may be positioned so as to surround the electrode lead 4 at at least one of the upper and lower portions of the electrode lead 4. The lead film 5 can prevent a short circuit from occurring in the electrode lead 4 during heat fusion and can improve the sealing performance between the sealing portion of the battery case 2 and the electrode lead 4.

[0037] Referring to FIGS. 3 and 4, a manufacturing apparatus for a secondary battery according to an embodiment of the present invention is an apparatus for forming, among the aforementioned electrode leads 4, particularly a portion protruding outside the battery case 2, and includes an upper fixing die 100 and a lower fixing die 200 for fixing the electrode lead 4, and a plurality of upper forming dies 300 and lower forming dies 400 for directly contacting the electrode lead 4 and forming the shape of the electrode lead 4.

[0038] The upper fixing die 100 and the lower fixing die 200 are for fixing the electrode lead 4 during the forming process, and particularly support the portion where the electrode lead 4 is fixed to the battery case 2 to fix the electrode lead 4. For this purpose, as shown in FIGS. 3 and 4, the upper and lower portions are formed to press while contacting the overlapping portion of the battery case 2 and the electrode lead 4, that is, the first fixing portion P1. Between the upper fixing die 100 and the lower fixing die 200 at the first fixing portion P1, together with the electrode lead 4, the lead film 5 surrounding the electrode lead and the battery case 2 heat-sealed to the lead film 5 can also be interposed and fixed.

[0039] The lower forming die 400 is arranged adjacent to the lower fixing die 200 at a distance from the outer end side of the electrode lead 4. The lower forming die 400 is configured to be in direct contact with the electrode lead 4 and coupled to the upper forming die 300 with the electrode lead 4 sandwiched therebetween, and the forming surface in contact with the electrode lead 4 has a shape corresponding to the shape of the electrode lead 4 to be formed. In this embodiment, the case of having three bending surfaces is taken as an example, but it is not limited thereto, and it can be variously deformed according to the final shape of the electrode lead 4 to be obtained.

[0040] The upper forming die 300 is arranged at a distance from the upper fixing die 100 to the outer end side of the electrode lead 4. A plurality of upper forming dies 300 may be provided. In this embodiment, the case of including three upper forming dies 300 is taken as an example for description, but it is not limited thereto, and the number and position of the upper forming dies 300 can be adjusted variously.

[0041] Referring to FIGS. 3 and 4, in this embodiment, the upper forming die 300 includes a first upper forming die 310, a second upper forming die 320, and a third upper forming die 330. These first upper forming die 310, second upper forming die 320, and third upper forming die 330 are sequentially arranged in the direction from the upper fixing die 100 toward the outer end of the electrode lead 4. The forming surface facing the lower forming die 400 in the state where the three upper forming dies 300 are combined has a shape corresponding to the shape of the electrode lead 4 to be formed. Further, the first upper forming die 310, the second upper forming die 320, and the third upper forming die 330 are formed separately from each other, and thus, they can be independently controlled during the process. For example, they can be controlled to descend one by one in the order of the first upper forming die 310, the second upper forming die 320, and the third upper forming die 330 and be coupled to the lower forming die 400 while pressing the electrode lead 4.

[0042] At this time, the first upper mold 310 can press the electrode lead 4 by sandwiching the electrode lead 4 between the lower mold 400 at the second fixing portion P2. The second fixing portion P2 is spaced apart from the first fixing portion P1 in the direction toward the outer end of the electrode lead 4. At the portion where the second fixing portion P2 is located, only the electrode lead 4 extends, and the lead film 5 and the battery case 2 are not located. Therefore, at the second fixing portion P2, since the fixing can be performed with only the electrode lead 4 disposed between the lower mold 400 and the first upper mold 310, the electrode lead 4 can be more surely pressed and fixed at the first fixing portion P1. Further, in some cases, by increasing the width of the second fixing portion P2 within a range where interference between the molds does not occur, the length of the electrode lead 4 fixed at the second fixing portion P2 can be increased, and thereby, the electrode lead 4 can be fixed with a stronger force.

[0043] The second upper mold 320 is spaced apart from the first upper mold 310 in the direction toward the outer end of the electrode lead 4. The molding surface of the second upper mold 320 may have a shape continuous from the first upper mold 310 and may have a shape corresponding to the first and second bending portions 41, 42 (shown in FIG. 7), but is not limited thereto, and may have various shapes according to the form of the electrode lead 4.

[0044] The third upper mold 330 is spaced apart from the second upper mold 320 in the direction toward the outer end of the electrode lead 4. The molding surface of the third upper mold 330 may have a shape continuous from the second upper mold 320 and may have a shape corresponding to the third bending portion 43 (shown in FIG. 6), but is not limited thereto, and may have various shapes according to the form of the electrode lead 4.

[0045] By separating and sequentially lowering such first to third upper molding dies 310, 320, and 330 from each other, they can be combined with the lower molding die 400 to form the electrode lead 4. According to such a configuration, first, the first upper molding die 310 performs additional fixing at the second fixing portion P2, so that the magnitude of the tensile force applied to the electrode lead 4 during the molding of the electrode lead 4 can be reduced. That is, the tensile force applied to the electrode lead 4, particularly the joint portion A between the electrode lead 4 and the electrode tab 3, is generated in the direction in which the electrode lead 4 is pulled during molding, but can only be reduced by the frictional force generated by fixing at the first and second fixing portions P1 and P2. Conventionally, fixing was performed only at the first fixing portion P1, and the electrode lead 4 was fixed via the lead film 5 and the battery case 2 at that portion, so the frictional force generated by fixing was not sufficient, and the magnitude of the tensile force generated during molding could not be reduced, and it was directly transmitted to the joint portion A between the electrode lead 4 and the electrode tab 3, resulting in problems such as wire breakage. However, in this embodiment, not only is additional fixing performed at the second fixing portion P2, but at that portion, only the electrode lead 4 is directly fixed, so the magnitude of the frictional force may be greater, and therefore, the magnitude of the tensile force generated during molding can be sufficiently reduced, so that the occurrence of wire breakage at the joint portion A between the electrode lead 4 and the electrode tab 3 can be prevented.

[0046] Also, compared to the case where the molding die presses the electrode lead 4 at once, since the molding die is divided and sequentially lowered and pressed, the magnitude of the tensile force generated at once can be reduced, so that the wire breakage of the electrode lead 4 can be effectively prevented. Thus, according to the manufacturing apparatus for a secondary battery according to an embodiment of the present invention, the tensile force applied to the electrode lead 4 and the electrode tab 3 during the bending molding of the electrode lead 4 can be minimized to prevent the occurrence of wire breakage.

[0047] Hereinafter, a manufacturing method using the manufacturing apparatus for a secondary battery described above will be described, which is a manufacturing method for a secondary battery according to an embodiment and other embodiments of the present invention.

[0048] FIGS. 5 to 7 are diagrams for explaining a method of manufacturing a secondary battery according to an embodiment of the present invention.

[0049] Referring to FIG. 5, in a method of manufacturing a secondary battery according to an embodiment of the present invention, first, an electrode lead 4 is fixed between an upper fixed mold 100 and a lower fixed mold 200 (a first fixed portion P1). Then, a first upper molding mold 310 is lowered toward a lower molding mold 400. At this time, the electrode lead 4 may be additionally fixed at a second fixed portion P2, or the upper molding mold 300 may simply be lowered so as to be applied sequentially without additional fixing. When additionally fixing, not only the electrode lead 4 but also a lead film 5 and a part of a battery case 2 may be fixed together at the first fixed portion P1, and only the electrode lead 4 may be fixed at the second fixed portion P2.

[0050] Also, at the first fixed portion P1 and the second fixed portion P2, pressure may be applied by the upper fixed mold 100 or the first upper molding mold 310 for additional fixing. Thereby, the electrode lead 4 can be fixed more reliably. At this time, the forces applied at the first fixed portion P1 and the second fixed portion P2 may be the same, or a larger force may be applied at the second fixed portion P2. At the second fixed portion P2, only the electrode lead 4 is fixed, and the electrode lead 4 has a higher strength than the battery case 2 fixed at the first fixed portion P1, etc., so there is a lower possibility of dents and damage occurring due to a larger pressure. Therefore, when it is necessary to increase the fixing strength, it is preferable to increase the fixing strength by increasing the pressing force at the second fixed portion P2.

[0051] Next, referring to FIG. 6, the second upper mold 320 disposed adjacent to the first upper mold 310 is lowered toward the lower mold 400 to form the first bending portion 41 and the second bending portion 42. That is, the first bending portion 41 may be formed at a portion where the first upper mold 310 and the second upper mold 320 are continuous, or may be bent by the second upper mold 320 descending while pressing the electrode lead 4. The second bending portion 42 may be formed by bending along the shape of the forming surface of the second upper mold 320.

[0052] Finally, referring to FIG. 7, the forming of the electrode lead 4 can be completed by lowering the third upper mold 330 to form the third bending portion 43.

[0053] Thus, in the manufacturing method of forming the electrode lead 4 using the manufacturing apparatus for a secondary battery according to an embodiment of the present invention, while the electrode lead 4 is being pressed and a tensile force is applied, the electrode lead 4 is fixed by the first and second fixing portions P1 and P2. Therefore, the tensile force applied to the electrode lead 4 can be reduced. In addition, since the molding die over the entire region of the electrode lead 4 applies the tensile force sequentially in the order close to the electrode assembly without applying the tensile force at once, the tensile force applied to the electrode lead 4 can be dispersed over time. Thus, it is possible to prevent disconnection that may occur when an excessive tensile force is applied to the electrode lead 4. Further, in the present embodiment, the upper mold 300 is divided into three steps for molding, but the present invention is not limited to this, and the upper mold 300 can be variously divided and molded according to the shape of the electrode lead 4 and the process situation.

[0054] Hereinafter, the tensile forces generated in the manufacturing method of a secondary battery according to an embodiment of the present invention and the manufacturing method of a secondary battery according to a comparative example will be measured, and the results will be described.

[0055] In Example 1, by the manufacturing method shown in FIGS. 5 to 7, the first to third upper molding dies 310, 320, and 330 were sequentially moved by about 12 mm. At this time, pressure was applied with a force of 45 kgf at the first fixing portion P1, and at the second fixing portion P2, the first upper molding die 310, the second upper molding die 320, and the third upper molding die 330 simply performed molding in sequence without being fixed.

[0056] In Example 2, molding was performed in the same manner as in Example 1, and additionally, pressure was applied with a force of 45 kgf at the second fixing portion P2 for fixing.

[0057] In Example 3, molding was performed in the same manner as in Example 2. The widths of the first upper molding die 310 and the lower molding die 400 were increased by 2.5 mm on the side of the fixing dies 100 and 200, and fixing was performed with the length of contact between the electrode lead 4 and the die increased at the second fixing portion P2. As a result, the contact area between the electrode lead 4 and the die at the second fixing portion P2 was increased by three times compared to Example 2, and consequently, pressure was applied with a force of 135 kgf, which was three times the increased force, for fixing at the second fixing portion P2.

[0058] On the other hand, in the comparative example, the upper die 30 was moved by about 12 mm in the same manner as in Example 1 using the dies shown in FIGS. 1 and 2 to mold the electrode lead 4.

[0059] During molding in Examples 1 to 3 and the comparative example, the maximum value of the tensile force applied to the joint portion A between the electrode tab 3 and the electrode lead 4 was measured. The results are shown in Table 1 below.

[0060]

Table 1

[0061] As shown in Table 1 above, in the case of the examples of the present invention, it was confirmed that the maximum tensile force value was significantly lower than that of the comparative example. Therefore, according to the examples of the present invention, it was found that disconnection of the electrode tab 3 and the electrode lead 4 can be prevented during the molding process of the electrode lead 4.

[0062] Although the preferred embodiments of the present invention have been described in detail above, the scope of the rights of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also belong to the scope of the rights of the present invention.

Description of Reference Numerals

[0063] 3: Electrode tab 4: Electrode lead 100: Upper fixed mold 200: Lower fixed mold 300: Upper forming mold 310: First upper forming mold 320: Second upper forming mold 330: Third upper forming mold 400: Lower forming mold

Claims

1. A manufacturing apparatus for a secondary battery, comprising a plurality of electrodes and separation membranes laminated alternately, an electrode tab provided at an end of the plurality of electrodes, and an electrode lead coupled to the electrode tab, an upper fixing die and a lower fixing die that sandwich and fix the electrode lead, a lower molding die disposed at a distance from the outer end side of the electrode lead from the lower fixing die, and a plurality of upper molding dies disposed at a distance from the end side of the electrode lead from the upper fixing die including, the plurality of upper molding dies includes a first upper molding die for fixing the electrode lead, and a second upper molding die for forming a first bending portion and a second bending portion, the first upper molding die and the second upper molding die are separated from each other and are sequentially arranged in a direction from the electrode assembly of the secondary battery toward the end of the electrode lead, a manufacturing apparatus for a secondary battery.

2. The manufacturing apparatus for a secondary battery according to claim 1, wherein the first upper molding die and the second upper molding die are movable independently of each other.

3. The manufacturing apparatus for a secondary battery according to claim 1 or 2, further comprising a third upper molding die disposed adjacent to the second upper molding die in a direction from the electrode assembly toward the end of the electrode lead, and forming a third bending portion.

4. The manufacturing apparatus for a secondary battery according to claim 3, wherein the third upper molding die is separated from the first upper molding die and the second upper molding die and is movable independently.

5. The manufacturing apparatus for a secondary battery according to claim 1, wherein only the electrode lead is disposed between the first upper molding die and the lower molding die.

6. A manufacturing method for a secondary battery, comprising a plurality of electrodes and separation membranes laminated alternately, an electrode tab provided at an end of the plurality of electrodes, and an electrode lead coupled to the electrode tab, a step of primarily fixing the electrode lead with a first fixing portion between an upper fixing die and a lower fixing die; a step of secondarily fixing the electrode lead by lowering a first upper molding die toward a lower molding die with a second fixing portion located at a distance from the outer end side of the electrode lead from the first fixing portion; a step of forming a first bending portion and a second bending portion on the electrode lead by lowering a second upper molding die located adjacent to the outer end side of the electrode lead and the first upper molding die toward the lower molding die; A method for manufacturing a secondary battery including

7. The method for manufacturing a secondary battery according to claim 6, including a step of lowering a third upper forming die located on the outer end side of the electrode lead from the second upper forming die toward the lower forming die to form a third bending portion on the electrode lead in a state where the second upper forming die is lowered.

8. The method for manufacturing a secondary battery according to claim 6 or 7, wherein only the electrode lead is disposed between the first upper forming die and the lower fixing die in the second fixing portion.

9. The method for manufacturing a secondary battery according to claim 8, wherein the electrode lead, a lead film surrounding the electrode lead, and a battery case of the secondary battery are disposed between the upper fixing die and the lower fixing die in the first fixing portion.

10. The method for manufacturing a secondary battery according to claim 6, wherein the same magnitude of force is applied to the upper fixing die and the first upper forming die to press the electrode lead in the first fixing portion and the second fixing portion.

11. The method for manufacturing a secondary battery according to claim 6, wherein the force for pressing the electrode lead by the first upper forming die in the second fixing portion is even greater than the force for pressing the electrode lead by the upper fixing die in the first fixing portion.

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