Method for manufacturing secondary battery

Abstract

The present invention relates to a method for manufacturing a secondary battery, the method comprising: a step of preparing a pouch case provided with an accommodating part in which an electrode assembly is accommodated, and a collecting part in which the electrode assembly is collected; a collection part which is in communication with the accommodation part and in which a gas generated during a charge / discharge process for activation is collected; a step of forming an opening in the collection part so as to discharge the gas collected in the collection part; a step for pressing at least a portion of the edge of the pouch case to the outside of the pouch case; and a step for forming a main sealing part for separating and sealing the accommodating part and the collecting part between the accommodating part and the collecting part after the bag case is pressed or in a state in which the bag case is pressed.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2022-0138752, filed on October 25, 2022, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a method for manufacturing a secondary battery. Background Art

[0004] Generally, unlike non-rechargeable primary batteries, secondary batteries are chargeable and dischargeable, and are widely used in electronic devices such as mobile phones, notebook computers, camcorders, electric vehicles, etc. In particular, since lithium secondary batteries have a larger capacity than nickel-cadmium batteries or nickel-metal hydride batteries and have a high energy density, their utilization has rapidly increased.

[0005] Secondary batteries may be divided into cylindrical or prismatic batteries in which an electrode assembly 2 is built into a cylindrical or prismatic metal can and pouch-type batteries in which an electrode assembly 2 is built into a pouch-type casing configured as a laminate.

[0006] Figure 1 is a diagram showing an example of a pouch-type secondary battery. The pouch-type secondary battery 1 includes an electrode assembly 2 in which electrodes and separators are alternately stacked, and a pouch-type housing 20, in which the electrode assembly 2 is accommodated. The electrode tabs 15 may be respectively connected to the electrodes of the electrode assembly. The electrode tabs 15 may be welded to each other on predetermined areas and then connected to the electrode lead 17 by welding. The housing 20 may include a receiving portion 21 for accommodating the electrode assembly 2. The receiving portion 21 of the housing 20 may be provided by one or two recesses. Figure 1 An example of the receiving portion 21 provided by two recessed portions is shown. A sealing portion (land portion) 23 may be provided around the circumference of the receiving portion 21 by heat fusion.

[0007] In a pouch type secondary battery, Figure 1 The bag-type shell 20 can be made of a bag shell, which includes a housing portion for housing the electrode assembly and a collecting portion for collecting the gas generated during the charging / discharging process for activation. The secondary battery requires a charging / discharging process for activation. Gas may be generated during the process, and the generated gas may be collected in the collecting portion. The gas collected in the collecting portion may be discharged to the outside of the bag shell through a degassing process. After the degassing process, a sealing portion may be provided between the housing portion and the collecting portion to separate and seal the housing portion from the collecting portion, and the collecting portion may be separated from the housing portion. Through this process, a Figure 1 Bag-type outer packaging 20.

[0008] However, due to the flexible nature of the bag shell, wrinkles may be generated on the bag shell during the preparation of the bag shell or during the degassing process. If the seal portion is provided in a wrinkled state, the sealing strength of the seal portion may be weakened. If the sealing strength is weakened, the high temperature storage performance and long life performance of the secondary battery may be weakened. Summary of the invention

[0009] Technical issues

[0010] An object of the present invention is to provide a method for manufacturing a secondary battery which does not cause a reduction in sealing strength due to wrinkles.

[0011] Technical Solution

[0012] In one embodiment, a method for manufacturing a secondary battery is provided, which includes: step (a): preparing a bag shell body, the bag shell body being provided with a housing portion and a collecting portion, the housing portion housing an electrode assembly, the collecting portion being connected to the housing portion and wherein a gas generated during a charge / discharge process for activation is collected in the collecting portion; step (b): forming an opening in the collecting portion to discharge the gas collected in the collecting portion; step (c): pressing at least a portion of an edge of the bag shell body toward the outside of the bag shell body; and step (d): forming a main sealing portion between the housing portion and the collecting portion after or while the bag shell body is pressed, the main sealing portion being used to separate and seal the housing portion from the collecting portion.

[0013] In another embodiment, step (c) may include a process of pressing at least a portion of the edge of the bag case from the inside of the bag case toward the outside.

[0014] In another embodiment, process (c) may include the following process: when forming the main seal, two of the edges of the bag shell are pressed to the outside of the bag shell in the direction where the main seal is to be formed, and the two edges pass through both ends of the main seal in a direction intersecting the main seal.

[0015] In another embodiment, the bag shell may include a first edge extending in a predetermined direction and disposed adjacent to the collecting portion, a second edge and a third edge extending from both ends of the first edge and disposed facing each other, and a fourth edge connecting the second edge and the third edge to each other, disposed facing the first edge and disposed adjacent to the accommodating portion.

[0016] In yet another embodiment, step (b) may include a process of removing at least a portion of the first sealing portion formed along the first edge to form an opening.

[0017] In another embodiment, step (c) may include inserting a pair of pressing bars into the bag case through the opening, and moving the pressing bars away from each other to press the second edge and the third edge of the bag case to the outside of the bag case.

[0018] In yet another embodiment, the press rod may be inserted in a direction toward the electrode assembly until an inner end of the press rod facing the electrode assembly is disposed adjacent to a location where the primary seal is to be formed.

[0019] In yet another embodiment, the compression rod may not be inserted into the bag housing beyond the position where the primary seal is to be formed.

[0020] In yet another embodiment, the pressure rod may be inserted into the bag housing and arranged parallel to the second edge and the third edge, respectively.

[0021] In yet another embodiment, in a state where the pressing bar is disposed parallel to the second edge and the third edge respectively, the pressing bar may move toward the second edge and the third edge to at least linearly contact the inner portion of the bag housing corresponding to the second edge and the third edge.

[0022] In yet another embodiment, each pressing bar may include a portion that gradually becomes thinner toward a side end facing the second edge or the third edge, and the portion is pressed by the pressing bar so that its thickness is thinnest at the side end.

[0023] In yet another embodiment, each press rod may include a portion that gradually becomes thinner toward an inner end facing the electrode assembly such that the thickness thereof is thinnest at the inner end.

[0024] In yet another embodiment, the method may further include a process of cutting the collecting portion outside the main sealing portion along the main sealing portion.

[0025] In still another embodiment, the collecting portion may be cut in a state where the bag housing is pressed.

[0026] Beneficial Effects

[0027] According to the present invention, since the main seal portion is formed in a state where wrinkles are removed or in a state where wrinkles are prevented from being generated, a secondary battery in which the sealing strength is not weakened due to wrinkles can be manufactured. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a diagram showing an example of a pouch-type secondary battery.

[0029] Figures 2 to 4 It is a diagram for explaining the degassing process of the prior art.

[0030] Figures 5 to 9 It is a diagram for explaining the method for manufacturing a secondary battery according to Example 1 of the present invention.

[0031] Fig.10 It is a diagram for explaining a method for manufacturing a secondary battery according to Example 2 of the present invention.

[0032] Fig.11 It is shown that the application Fig.10 A perspective view of a press rod of the manufacturing method.

[0033] Fig.12 yes Fig.11 Cross-sectional view of the compression rod taken along line AA.

[0034] Fig.13 yes Fig.11 Cross-sectional view of the compression rod taken along line BB. DETAILED DESCRIPTION

[0035] Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in several different forms and is not limited or constrained by the following embodiments.

[0036] In order to explain the present invention clearly, parts that are not related to the description or detailed descriptions of related known technologies that may unnecessarily obscure the gist of the present invention have been omitted, and in this specification, reference numerals are added to the components in each of the accompanying drawings. In this case, the same or similar reference numerals are assigned to the same or similar elements throughout the specification.

[0037] Furthermore, the terms or words used in the specification and claims should not be restrictively interpreted as ordinary meanings or dictionary-based meanings, but should be interpreted as meanings and concepts consistent with the scope of the present invention based on the principle that the inventor can appropriately define the concepts of the terms in order to best describe and interpret his or her invention.

[0038] The pouch type secondary battery may be manufactured through the following process.

[0039] First, the electrode assembly 2 may be prepared and then housed in the pouch case 310 (see Figure 2 ). The bag housing 310 can be prepared by connecting two bags disposed facing each other in a state where the electrode assembly 2 is accommodated. The two bags can be connected to each other in a state of being prepared separately. Three of the four edges of the two bags can be sealed and connected by hot melt. The sealing portion can be provided by the above-mentioned sealing. The opening for injecting electrolyte can be defined by one edge that is not at least partially sealed. Alternatively, the bag housing 310 can be prepared by folding one bag (see Figure 1 ). The folded portion of a bag may not be sealed. For reference, Figure 2The pouch housing 310 is shown sealed after the electrolyte is injected, which will be described later. For example, the sealing portion 331 may not be provided Figure 2 The edge 321 of the substrate 320 is provided so that the electrolyte can be injected, and then the sealing portion 331 can be provided on the edge 321 after the electrolyte is injected.

[0040] Next, the electrolyte may be injected into the pouch case 310 through the non-sealed edge of the pouch case 310. The electrode assembly 2 may be impregnated with the injected electrolyte.

[0041] Next, the unsealed edge of the bag case 310 may be sealed. As a result, the bag case 310 may be completely sealed.

[0042] Next, the battery can be charged and discharged for activation. Charging and discharging may occur several times, and gases may be generated in the process.

[0043] Next, a degassing process may be performed to remove the gas generated during the charging and discharging process. Figures 2 to 4 This is described in detail. Figures 2 to 4 It is a diagram for explaining the degassing process of the prior art.

[0044] The bag housing 310 including the receiving portion 311 and the collecting portion 312 can be prepared through the above process (see Figure 2 ). The inner space of the bag housing 310 may be divided into a space for accommodating the electrode assembly 2 and a space for collecting gas. The former may be a receiving portion 311, and the latter may be a collecting portion 312. The electrode assembly 2 may be accommodated in the receiving portion 311. To this end, a receiving portion 21 for receiving the electrode assembly 2 may be formed in the receiving portion 311 (see Figure 1 ). The collecting portion 312 may be a partial space in the pouch case 310 that communicates with the receiving portion 311, and may be a space for collecting gas generated during a charging and discharging process for activation.

[0045] Figure 2 An example of a bag housing 310 provided by folding a bag is shown. Figure 2 In addition to the folded portion 324 of the bag case 310, the sealing portions 331 to 333 may be respectively provided on the remaining edges 321 to 323. For reference, the electrode lead 17 electrically connected to the electrode assembly 2 may extend from both longitudinal ends of the electrode assembly 2 to protrude to the outside of the bag case 310, such as Figure 2 shown.

[0046] When the bag housing 310 is prepared, a linear gap 341 may be formed in the collecting portion 312 of the bag housing 310 (see Figure 3). For this purpose, a knife may be used. When the opening 341 is formed, the gas collected in the collecting portion 312 may be discharged to the outside of the bag housing 310 through the slit 341. In order to facilitate the discharge of the gas, the bag housing 310 may be placed under a vacuum atmosphere.

[0047] When the gas is completely exhausted, the main sealing portion 334 may be formed between the receiving portion 311 and the collecting portion 312 (see Figure 4 ). The main sealing portion 334 may be a portion for separating and sealing the receiving portion 311 from the collecting portion 312, and may be formed by heat melting in the same manner as the other sealing portions 331 to 333 are formed.

[0048] However, due to the flexible property of the bag case 310, wrinkles (ridges) may be easily formed on the bag case 310. For example, wrinkles may be formed while the bag case 310 is being prepared or while gas is being exhausted through the slits 341.

[0049] Typically, the bag housing 310 may be made of a bag film including a metal layer made of metal (e.g., aluminum), an inner resin layer (e.g., a layer made of polypropylene) disposed inside the metal layer, and an outer resin layer (e.g., a layer made of polyethylene terephthalate) disposed outside the metal layer. When the main seal 334 is formed in a wrinkled state, stress may be concentrated on the inner resin layer of the bag housing 310, and therefore, the inner resin layer may be more easily melted. This may weaken the sealing strength of the seal 334. If the sealing strength of the seal becomes weak, the seal may be accidentally ruptured when high temperature is generated or when used for a long time. As a result, if the main seal 334 is formed in a wrinkled state, the high temperature storage performance and long-term life performance of the secondary battery may be weakened.

[0050] The method for manufacturing a secondary battery according to Embodiment 1 described below is characterized in that, in order to solve the above-mentioned problem, the main seal portion is formed in a state where wrinkles (protuberances) are removed (or the occurrence of wrinkles is prevented). Figures 5 to 9 A method for manufacturing the secondary battery of Example 1 will be described.

[0051] Example 1

[0052] Figures 5 to 9 It is a diagram for explaining the method for manufacturing a secondary battery according to Example 1 of the present invention.

[0053] First, if Figure 5 As shown, a pouch case 110 provided with a receiving part 111 receiving the electrode assembly 2 and a collecting part 112 collecting gas generated during a charge / discharge process for activation may be prepared. Figure 5 The bag housing 110 can be Figure 2 The bag housing 110 is the same.

[0054] The bag housing 110 may include four edges 121 to 124, such as Figure 5 The first edge 121 may be a portion of the bag housing 110 in a predetermined direction (eg, Figure 5 The second edge 122 and the third edge 123 may be edges of the bag body 110 that extend from both ends of the first edge 121 and are disposed to face each other. The fourth edge 124 may be an edge that connects the second edge 122 and the third edge 123 to each other, is disposed to face the first edge 121, and is disposed to be adjacent to the receiving portion 111.

[0055] The first to third sealing portions 131, 132 and 133 formed by heat fusion may be respectively disposed on the first to third edges 121, 122 and 123 of the bag body 110. As described above, the fourth edge 124 of the bag body 110 may be a portion where a bag is folded, and a sealing portion may not be disposed on the fourth edge 124.

[0056] Next, an opening 141 may be formed in the collecting portion 112 (see Figure 7 ) to discharge the gas collected in the collecting portion 112. The opening 141 of the collecting portion 112 can be formed by removing at least a portion of the first sealing portion 131 formed along the first edge 121. For example, the bag housing 110 can be formed along the inside of the first sealing portion 131. Figure 5 The cutting line L1 is cut to form the opening 141. When considering the pressure rod 150 (see Figure 8 ) when moving, the entire first sealing portion 131 can be removed. After this process, the bag housing 110 can have a Figure 6 Shape shown.

[0057] In order to promote the discharge of gas, the bag housing 110 can be placed under a vacuum atmosphere. For example, the bag housing 110 can be placed in a vacuum chamber capable of forming a vacuum. Even while maintaining the vacuum, pressure can be applied to the edge of the bag housing 110. This will be described later.

[0058] Next, at least a portion of the edge of the bag housing 110 may be pressed to the outside of the bag housing 110. Due to this pressing, wrinkles formed on the bag housing 110 may be removed. Fig. 9 ) applies pressure, wrinkles can be prevented from occurring during the formation process of the main seal 134.

[0059] Below, refer to Figures 6 to 8 The pressing process will be described in detail.

[0060] In this embodiment, the pressing of the bag housing 110 can be achieved by the pressing rod 150. The pressing rod 150 of this embodiment can be Figure 6 The vertical direction and the left-right direction of the bag body 110 are moved to press the bag body 110. This movement can be made by Figure 6 The driving portion 160 is realized. The driving portion 160 may include a support portion 161 and a movable portion 162 that moves in a vertical direction relative to the support portion 161. The pressure rod 150 may be connected to the movable portion 162 so as to be movable in the left-right direction. When the pressure rod 150 needs to move vertically (for example, when the pressure rod is inserted into the bag shell through the opening), the movable portion 162 may move in the vertical direction along the support portion 161. When the left-right movement of the pressure rod 150 is required (for example, when the edge of the bag shell is pressed outward by the pressure rod), the pressure rod 150 may move in the left-right direction along the movable portion 162.

[0061] First, if Figure 7 As shown, a pair of pressing rods 150 may be inserted into the bag housing 110 through an opening 141 of the bag housing 110 , the opening 141 being formed by removing the first sealing portion 131 .

[0062] The pressing rod 150 can be moved in a direction toward the electrode assembly 2 (eg, Figure 7 The pressing rod 150 is inserted in the downward direction until the inner end 151 of the pressing rod 150 facing the electrode assembly 2 is arranged to be in contact with the main sealing portion 134 (see Fig. 9 Here, the pressing rod 150 may not be inserted beyond the position P where the main seal 134 is to be formed in the bag housing 110. For example, the pressing rod 150 may be inserted only to a position that does not overlap with the position P where the main seal 134 is to be formed. The forming process of the main seal 134, which will be described later, can be performed while keeping the pressing of the pressing rod 150, and the reason for doing so is that the pressing rod 150 does not interfere with the forming process of the main seal 134.

[0063] Next, if Figure 8 As shown, the pressure rods 150 can be moved in a direction away from each other (for example, see Figure 8 The second edge 122 and the third edge 123 of the bag housing 110 are respectively pressed to the outside of the bag housing 110. Due to this pressing, wrinkles formed on the bag housing 110 can be removed. Fig. 9 ) applies pressure, it is possible to prevent wrinkles from occurring during the formation process of the main seal portion 134. In the case of this embodiment, the pressure rod 150 can be used to directly press many parts of the second edge 122 and the third edge 123, so wrinkles can be removed or prevented from occurring very effectively.

[0064] The second edge 122 and the third edge 123 of the edge of the bag housing 110 may be formed when the main seal 134 is formed (see Fig. 9 ;See Figure 8 When the position P of the main seal portion is to be formed, in the cross direction of the main seal portion (such as Figure 8 The second edge 122 and the third edge 123 may pass through the two edges at both ends of the main seal portion 134 in the direction in which the main seal portion 134 is to be formed (for example, Figure 8 The main seal portion 134 is formed on the bag housing 110, such as Figure 4 As shown in the partially enlarged view of , therefore, when the edge of the bag shell 110 is pressed in the above direction, wrinkles can be effectively removed.

[0065] like Figure 7 As shown, the pressure bar 150 can be inserted into the bag housing 110 and arranged parallel to the second edge 122 and the third edge 123. For example, in the pressure bar 150, the left pressure bar 150L can be arranged parallel to the second edge 122, and the right pressure bar 150R can be arranged parallel to the third edge 123. Here, in the state where the pressure bar 150 is arranged parallel to the second edge 122 and the third edge 123, as shown in FIG. Figure 8 As shown, the pressing bar 150 may move toward the second edge 122 and the third edge 123 so as to linearly contact with the inner portion of the bag housing 110 corresponding to the second edge 122 and the third edge 123 .

[0066] For example, when the left end of the left pressure bar 150L is formed sharply, the left end of the left pressure bar 150L may be in linear contact with the inside of the bag housing 110 on which the second sealing portion 132 is formed. When the left end of the left pressure bar 150L is formed in an arc shape, the left end of the left pressure bar 150L may be in contact with the inner surface of the bag housing 110. As described above, the pressure bar 150 of this embodiment may be in contact with the inside of the bag housing 110 in as wide a range as possible. This may be very effective in removing wrinkles or preventing the occurrence of wrinkles.

[0067] After pressing the bag housing 110, as Fig. 9 As shown, the main seal 134 may be formed between the receiving portion 111 and the collecting portion 112 to separate and seal the receiving portion 111 from the collecting portion 112. The main seal 134 may be formed by hot melting. If the main seal 134 is formed while the bag housing 110 is kept pressed, wrinkles may be prevented from occurring during the formation of the main seal 134.

[0068] Next, the collection portion 112 may be cut along the main seal 134 on the outside of the main seal 134. For example, the bag body 110 may be cut along Fig. 9 L2 in the bag housing 110 is cut to remove the collecting portion 112. As a result, a pouch-type secondary battery can be manufactured. Even during such cutting, the pressing of the pressing bar 150 can be applied. If the bag housing 110 is cut in a state where the second edge 122 and the third edge 123 of the bag housing 110 are supported by the pressing bar 150, the cutting process can be stable.

[0069] Even during the discharge of the collected gas, the pressing of the pressing rod 150 may be applied. For example, if the pressing of the pressing rod 150 is applied even during the discharge of the gas, Figure 8 The pressure in the bag body 110 can prevent the second edge 122 and the third edge 123 of the bag body 110 from curling inward during gas discharge and causing wrinkles on the bag body 110. In order to promote gas discharge, gas discharge can be performed under a vacuum atmosphere, and in a vacuum atmosphere, the curling of the second edge 122 and the third edge 123 may be more serious. However, if the pressure bar 150 supports the second edge 122 and the third edge 123, the above curling can be prevented.

[0070] Example 2

[0071] Fig.10 1 is a diagram for explaining a method for manufacturing a secondary battery according to Example 2 of the present invention. The manufacturing method of Example 2 differs from the manufacturing method of Example 1 in the structure of the pressure rod. The manufacturing method of Example 2 will be described below with these points as the focus.

[0072] Reference Figures 5 to 9 The contents described above can be similarly applied to the manufacturing method of Example 2. Fig.10 As shown, in this embodiment, the structure of the pressing rod 250 for pressing the bag housing 110 is different from the above content.

[0073] Reference Figures 11 to 13 The pressure rod of this embodiment will be described. Fig.11 It is shown that the application Fig.10 A perspective view of a pressure rod of the manufacturing method, Fig.12 It is taken along line AA Fig.11 The interface diagram of the pressure rod, Fig.13 It was taken along line BB Fig.11 For reference, Fig.11 The pressure bar in the Fig.10 The right pressure rod 250R of the pressure rod 250 in the figure.

[0074] The pressing rod 250 of this embodiment may include a portion that gradually becomes thinner toward the side end of the second edge 122 or the third edge 123 facing the bag housing 110, and the portion will be pressed by the pressing rod so that its thickness is thinnest at the side end. Fig.11 As shown, Fig.10 The right pressure rod 250R may include a side end 252 facing the third edge 123, and as Fig.12 As shown, the thickness t2 may gradually become thinner toward the side end 252 , and thus, the thickness t2 may be thinnest at the side end 252 .

[0075] Since the edge of the bag case 110 is fitted, the space where the press rod 250 is inserted may become narrower as the edge inside the bag case 110 is approached. As described above, if the press rod 250 includes a portion with a gradually thinning thickness, the insertion of the press rod 250 can be facilitated even in a narrow space.

[0076] exist Fig.12 In the figure, the right half of the right pressure bar 250R is shown as a shape with a thinner overall thickness, but the shape of the right pressure bar 250R is not limited thereto. For example, the thickness may be thinner only at a portion adjacent to the side end 252 of the right half of the right pressure bar 250R. Fig.12 In the figure, the left half of the right pressure rod 250R is shown in a symmetrical shape of the right half, but the shape of the left half is not limited thereto. For example, the left half may have a rectangular cross section. However, if the left half is formed in a symmetrical shape with the right half, a pressure rod of a single shape may be used as the left and right pressure rods.

[0077] The pressure rod 250 of the present embodiment may include a portion that gradually becomes thinner toward the inner end 251 facing the electrode assembly 2 and has the thinnest thickness at the inner end 251. For example, Fig.10 The pressure rod 250 may include Fig.11 The inner end 251 shown facing the electrode assembly 2 and as Fig.13 As shown, the thickness t1 may gradually become thinner toward the inner end 251, and thus, the thickness t1 may be thinnest at the inner end 251. Fig.10 As shown, the inner end 251 of the pressing rod 250 may be first inserted into the opening 141. As the thickness gradually becomes thinner toward the inner end 251, the pressing rod 250 may be easily inserted into the opening 141.

[0078] The above-disclosed subject matter is to be considered illustrative rather than restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments that fall within the true spirit and scope of the present invention.

[0079] Therefore, the embodiments of the present invention should be considered illustrative rather than restrictive, and the technical spirit of the present invention is not limited to the foregoing embodiments.

[0080] Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.

Claims

1. A method for manufacturing a secondary battery, the method comprising: include: Step (a): preparing a bag case provided with a housing portion and a collecting portion in which the electrode assembly is housed, the collecting portion being in communication with the housing portion and in which gas generated during a charge / discharge process for activation is collected; Step (b): forming an opening in the collecting portion to discharge the gas collected in the collecting portion; Step (c): pressing at least a portion of the edge of the bag shell toward the outside of the bag shell; and Step (d): after the bag case is pressed or in a state where the bag case is pressed, forming a main seal portion between the storage portion and the collecting portion, the main seal portion being used to separate and seal the storage portion from the collecting portion.

2. The method according to claim 1, in, The step (c) includes a process of pressing at least a portion of the edge of the bag case outward from the inside of the bag case.

3. The method according to claim 1, in, The process (c) includes the following process: when forming the main seal, two edges of the bag shell are pressed to the outside of the bag shell in the direction where the main seal is to be formed, and the two edges pass through both ends of the main seal in a direction intersecting the main seal.

4. The method according to claim 1, in, The bag housing comprises: a first edge extending in a predetermined direction and disposed adjacent to the collecting portion; a second edge and a third edge, the second edge and the third edge respectively extending from both ends of the first edge and arranged facing each other; and A fourth edge connects the second edge and the third edge to each other, is disposed facing the first edge, and is disposed adjacent to the accommodation portion.

5. The method according to claim 4, in, The step (b) includes removing at least a portion of a first sealing portion formed along the first edge to form an opening.

6. The method according to claim 4, in, The step (c) comprises: The process of inserting a pair of pressure rods into the bag housing through the opening; and The pressing rods are moved in directions away from each other, thereby pressing the second edge and the third edge of the bag case to the outside of the bag case.

7. The method according to claim 6, in, The press rod is inserted in a direction toward the electrode assembly until an inner end of the press rod facing the electrode assembly is disposed adjacent to a position where the main seal is to be formed.

8. The method according to claim 7, in, The press bar is not inserted into the bag housing beyond the position where the primary seal is to be formed.

9. The method according to claim 6, in, The pressing rods are inserted into the bag housing and are arranged parallel to the second edge and the third edge, respectively.

10. The method according to claim 9, in, In a state where the pressing bar is disposed parallel to the second edge and the third edge, respectively, the pressing bar moves toward the second edge and the third edge to be in at least linear contact with the inner portion of the bag case corresponding to the second edge and the third edge.

11. The method according to claim 6, in, The pressing bars each include a portion that gradually becomes thinner toward a side end facing the second edge or the third edge, and the portion to be pressed by the pressing bar is thinnest at the side end.

12. The method according to claim 6, in, The press rods each include a portion that gradually becomes thinner toward an inner end facing the electrode assembly such that a thickness thereof is thinnest at the inner end.

13. The method according to claim 1, further comprising a process of cutting the collecting portion outside the main seal portion along the main seal portion.

14. The method according to claim 12, in, The collecting portion is cut in a state where the bag case is pressed.

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