Secondary battery manufacturing method

Abstract

The present invention relates to a method for manufacturing a secondary battery, and may include the steps of: preparing a pouch case having a storage section for storing an electrode assembly and a collection section that is connected to the storage section and collects gas generated during a charge / discharge process for activation; forming an opening in the collection section to discharge the gas collected in the collection section; pressurizing at least a portion of an edge of the pouch case toward the outside of the pouch case; and forming a main seal section between the storage section and the collection section after or while the pouch case is pressurized, for separating and sealing the storage section from the collection section.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0138752, filed October 25, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a method for manufacturing a secondary battery. [Background technology]

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

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

[0005] FIG. 1 is a diagram showing an example of a pouch-type secondary battery. The pouch-type secondary battery 1 includes an electrode assembly 2 formed by alternately stacking electrodes and separators, and a pouch-type exterior material 20 in which the electrode assembly 2 is housed. Electrode tabs 15 may be connected to the electrodes of the electrode assembly 2. The electrode tabs 15 may be welded to the electrode assembly 2 in predetermined areas and then connected to electrode leads 17 by welding. The exterior material 20 may include a housing portion 21 for housing the electrode assembly 2. The housing portion 21 of the exterior material 20 may be formed with one or two indented portions. FIG. 1 illustrates an example of a housing portion 21 formed with two indented portions. A seal portion 23 (terrace) may be formed around the periphery of the housing portion 21 by thermal fusion.

[0006] Meanwhile, in a pouch-type secondary battery, the pouch-type outer casing 20 of FIG. 1 can be manufactured from a pouch case including a storage section that stores an electrode assembly and a collection section that collects gas generated during the charge / discharge process for activation. A secondary battery requires a charge / discharge process for activation. Gas is generated during this process, and the generated gas can be collected in the collection section. The gas collected in the collection section can be discharged to the outside of the pouch case in a degassing process. After the degassing process, a seal section is formed between the storage section and the collection section to separate and seal the storage section from the collection section, and the collection section can be separated from the storage section. Through this process, the pouch-type outer casing 20 of FIG. 1 can be formed.

[0007] However, due to the flexibility of the pouch case, wrinkles are easily formed in the pouch case during preparation or degassing. If the seal is formed in a wrinkled state, the seal strength of the seal may be reduced. The reduced seal strength may result in a reduction in the high-temperature storage performance and long-term life performance of the secondary battery. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a method for manufacturing a secondary battery that does not cause a decrease in seal strength due to wrinkles. [Means for solving the problem]

[0009] In one example, a method for manufacturing a secondary battery may include the steps of: (a) preparing a pouch case having a storage section in which an electrode assembly is stored and a collection section that is connected to the storage section and that collects gas generated during a charging / discharging process for activation; (b) forming an opening in the collection section to discharge the gas collected in the collection section; (c) pressurizing at least a portion of the edge of the pouch case toward the outside of the pouch case; and (d) forming a main seal section between the storage section and the collection section after or while the pouch case is pressurized to separate and seal the storage section from the collection section.

[0010] In another example, step (c) may be a step of applying pressure to at least a portion of the edge of the pouch case from the inside to the outside of the pouch case.

[0011] In yet another example, step (c) may be a step of pressing two edge portions of the pouch case that pass through both ends of the main seal portion in a direction that crosses the main seal portion when the main seal portion is formed, against the outside of the pouch case in the direction in which the main seal portion is formed.

[0012] In yet another example, the pouch case may include a first edge portion extending in a predetermined direction and positioned adjacent to the collection section, second and third edge portions extending from both ends of the first edge portion and positioned opposite each other, and a fourth edge portion connecting the second and third edge portions, positioned opposite the first edge portion, and positioned adjacent to the storage section.

[0013] In yet another example, step (b) may be a step of removing at least a portion of a first seal portion formed along the first edge portion to form the opening.

[0014] In yet another example, step (c) may include the steps of inserting a pair of pressure rods into the interior of the pouch case through the opening, and moving the pressure rods away from each other to pressurize the second and third edges of the pouch case against the outside of the pouch case, respectively.

[0015] In yet another example, the pressure rod may be inserted in a direction toward the electrode assembly until an inner end of the pressure rod facing the electrode assembly is positioned adjacent to a position where the main seal portion is formed.

[0016] In yet another example, the pressure rod may not be inserted into the pouch case beyond the position where the main seal portion is formed.

[0017] In yet another example, the pressure rods may be inserted inside the pouch case and arranged parallel to the second and third edges, respectively.

[0018] In yet another example, the pair of pressure rods may be arranged parallel to the second and third edges, respectively, and move toward the second and third edges so as to make at least line contact with the internal portions of the pouch case corresponding to the second and third edges.

[0019] In yet another example, each of the pair of pressure rods may include a portion whose thickness gradually decreases toward the side end facing the second edge or the third edge that it applies pressure to, and whose thickness is thinnest at the side end.

[0020] In yet another example, each of the pair of pressure rods may include a portion whose thickness gradually decreases toward an inner end facing the electrode assembly, the inner end being the thinnest in thickness.

[0021] In yet another example, the method for manufacturing a secondary battery may further include cutting off the collection portion along the main seal portion and outside the main seal portion.

[0022] In yet another example, the collection portion may be cut off while the pouch case is in a pressurized state. [Effects of the Invention]

[0023] According to the present invention, the main seal portion can be formed in a state where wrinkles are removed or where the occurrence of wrinkles is prevented, so that a secondary battery can be manufactured in which the seal strength is not reduced due to wrinkles. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a diagram showing an example of a pouch-type secondary battery. [Figure 2] FIG. 1 is a diagram for explaining a conventional degassing process. [Figure 3] FIG. 1 is a diagram for explaining a conventional degassing process. [Figure 4] FIG. 1 is a diagram for explaining a conventional degassing process. [Figure 5] 2A to 2C are diagrams illustrating a method for manufacturing a secondary battery according to the first embodiment of the present invention. [Figure 6] 2A to 2C are diagrams illustrating a method for manufacturing a secondary battery according to the first embodiment of the present invention. [Figure 7] 2A to 2C are diagrams illustrating a method for manufacturing a secondary battery according to the first embodiment of the present invention. [Figure 8] 2A to 2C are diagrams illustrating a method for manufacturing a secondary battery according to the first embodiment of the present invention. [Figure 9] 2A to 2C are diagrams illustrating a method for manufacturing a secondary battery according to the first embodiment of the present invention. [Figure 10] 10A to 10C are diagrams illustrating a method for manufacturing a secondary battery according to a second embodiment of the present invention. [Figure 11] 11 is a perspective view showing a pressure rod used in the manufacturing method of FIG. 10. FIG. [Figure 12] 12 is a cross-sectional view of the pressure rod of FIG. 11 taken along line AA. [Figure 13] 12 is a cross-sectional view of the pressure rod of FIG. 11 taken along the line BB. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily understand the preferred embodiments of the present invention. However, the present invention can be realized in various different forms and is not limited to the following embodiments.

[0026] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may obscure the gist of the present invention will be omitted, and when assigning reference symbols to components in each drawing in this specification, the same or similar reference symbols will be assigned to the same or similar components throughout the specification.

[0027] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, in accordance with the principle that an inventor can appropriately define the concept of a term in order to best explain his or her invention.

[0028] The pouch-type secondary battery can be manufactured through the following process.

[0029] First, the electrode assembly 2 is prepared, and then it can be housed in the pouch case 310 (see FIG. 2). The pouch case 310 may be formed by joining two pouches arranged opposite each other with the electrode assembly 2 housed therein. The two pouches may also be provided separately and joined together. Three of the four edges of the two pouches may be sealed and joined by heat fusion. The sealed portion may be formed by such sealing. An opening for injecting the electrolyte may be formed by one edge that is at least partially unsealed. Alternatively, the pouch case 310 may be formed by folding one pouch (see FIG. 1). The folded portion of the pouch may not be sealed. Note that FIG. 2 shows the pouch case 310 after the sealing process has been completed after the electrolyte has been injected, as described below. For example, the edge portion 321 in FIG. 2 does not have the seal portion 331 formed thereon, so that the electrolyte can be injected therethrough, and the seal portion 331 may be formed on the edge portion 321 after the electrolyte is injected.

[0030] Next, an electrolyte solution can be injected into the pouch case 310 through an unsealed edge of the pouch case 310. The electrode assembly 2 may be impregnated with the injected electrolyte solution.

[0031] Next, the unsealed edges of the pouch case 310 can be sealed, thereby sealing the pouch case 310 entirely.

[0032] The battery can then be charged and discharged for activation, possibly multiple times, during which gas may be generated.

[0033] Next, a degassing step can be carried out to remove gas generated during the charge / discharge steps. This will be described in detail below with reference to Figures 2 to 4. Figures 2 to 4 are diagrams for explaining a conventional degassing step.

[0034] Through the above process, a pouch case 310 having a storage portion 311 and a collecting portion 312 can be prepared (see FIG. 2). The internal space of the pouch case 310 may be divided into a space for storing the electrode assembly 2 and a space for collecting gas. The former may be the storage portion 311, and the latter may be the collecting portion 312. The electrode assembly 2 may be stored in the storage portion 311. To this end, the storage portion 311 may be formed with a storage portion 21 (see FIG. 1) for storing the electrode assembly 2. The collecting portion 312 may be a portion of the space within the pouch case 310 that is connected to the storage portion 311 and that is used to collect gas generated during the charge / discharge process for activation.

[0035] Fig. 2 shows an example of a pouch case 310 formed by folding one pouch. In the pouch case 310 of Fig. 2, seal portions 331 to 333 are formed on the other edge portions 321 to 323, excluding the folded portion 324. Note that the electrode lead 17 electrically connected to the electrode assembly 2 may extend from both ends of the electrode assembly 2 in the longitudinal direction and protrude outside the pouch case 310, as shown in Fig. 2.

[0036] Once pouch case 310 is prepared, linear gap 341 can be formed in collection section 312 of pouch case 310 (see FIG. 3). A knife may be used for this purpose. Once gap 341 is formed, the gas trapped in collection section 312 can be discharged through gap 341 to the outside of pouch case 310. To facilitate the discharge of gas, pouch case 310 may be placed in a vacuum atmosphere.

[0037] Once all the gas has been discharged, main seal 334 can be formed between storage section 311 and collection section 312 (see FIG. 4). Main seal 334 is a part for separating and sealing storage section 311 from collection section 312, and may be formed by heat fusion, like the other seals 331 to 333.

[0038] However, due to the flexible characteristics of the pouch case 310, wrinkles (wrinkles) are likely to form in the pouch case 310. For example, wrinkles are likely to form during preparation of the pouch case 310 or while gas is being released from the gap 341.

[0039] The pouch case 310 can be manufactured from a pouch film that typically includes a metal layer (e.g., aluminum), an inner resin layer (e.g., polypropylene) disposed inside the metal layer, and an outer resin layer (e.g., polyethylene terephthalate) disposed outside the metal layer. However, if the main seal portion 334 is formed in a wrinkled state, stress may concentrate on the inner resin layer inside the pouch case 310, causing the inner resin layer to melt more. This may reduce the seal strength of the seal portion 334. If the seal strength of the seal portion is reduced, the seal portion may be unintentionally opened during high temperatures or long-term use. In other words, if the main seal portion 334 is formed in a wrinkled state, the high-temperature storage performance and long-term life performance of the secondary battery may be reduced.

[0040] The method for manufacturing a secondary battery according to the first embodiment described below is characterized in that, in order to solve the above problem, the main seal is formed in a state in which wrinkles (waviness) are removed (or in a state in which the occurrence of wrinkles is prevented). Hereinafter, the method for manufacturing a secondary battery according to the first embodiment will be described with reference to Figs. 5 to 9.

[0041] Embodiment 1 5 to 9 are diagrams illustrating the method for manufacturing the secondary battery according to the first embodiment of the present invention.

[0042] First, as shown in Fig. 5, a pouch case 110 may be prepared, which includes a storage section 111 for storing the electrode assembly 2 and a collection section 112 for collecting gas generated during the charge / discharge process for activation. The pouch case 110 of Fig. 5 may be the same as the pouch case 310 of Fig. 2 described above.

[0043] As shown in Fig. 5, the pouch case 110 may include four edges 121 to 124. The first edge 121 may extend in a predetermined direction (e.g., the left-right direction in Fig. 5) and may be an edge of the pouch case 110 disposed adjacent to the collecting section 112. The second and third edges 122, 123 may extend from both ends of the first edge 121 and may be edges of the pouch case 110 positioned opposite each other. The fourth edge 124 may be an edge of the pouch case 110 that connects the second and third edges 122, 123, is positioned opposite the first edge 121, and is disposed adjacent to the storage section 111.

[0044] First to third seal portions 131, 132, 133 formed by heat sealing may be provided on first to third edge portions 121, 122, 123 of pouch case 110, respectively. Fourth edge portion 124 of pouch case 110 may be a portion where one pouch is folded, as described above, and fourth edge portion 124 may not be provided with a seal portion.

[0045] Next, an opening 141 (see FIG. 7) is formed in the collecting portion 112 to allow the gas trapped in the collecting portion 112 to be discharged. The opening 141 in the collecting portion 112 may be formed by removing at least a portion of the first seal portion 131 formed along the first edge portion 121. For example, the opening 141 may be formed by cutting the pouch case 110 along the incision line L1 in FIG. 5 inside the first seal portion 131. Considering the movement of the pressure rod 150 (see FIG. 8), which will be described later, the entire first seal portion 131 may be removed. Through this process, the pouch case 110 may have the shape shown in FIG. 6.

[0046] To promote the gas discharge, the pouch case 110 may be placed in a vacuum atmosphere. For example, the pouch case 110 may be placed in a vacuum chamber capable of forming a vacuum. Pressurization may also be applied to the edges of the pouch case 110 while the vacuum is maintained. This will be described later.

[0047] Next, at least a portion of the edge of the pouch case 110 can be pressed against the outside of the pouch case 110. Such pressing can remove wrinkles that have formed in the pouch case 110. If such pressing is also applied during the process of forming a main seal portion 134 (see FIG. 9 ), which will be described later, it is possible to prevent wrinkles from occurring during the process of forming the main seal portion 134.

[0048] The pressurization process will be described in detail below with reference to FIGS.

[0049] In this embodiment, pressure is applied to the pouch case 110 by a pressure rod 150. The pressure rod 150 of this embodiment can move up and down and left and right with reference to FIG. 6 in order to apply pressure to the pouch case 110. Such movement can be achieved by a drive unit 160 shown in FIG. 6. The drive unit 160 may include a support part 161 and a moving part 162 that is configured to move up and down relative to the support part 161. The pressure rod 150 may be coupled to the moving part 162 so as to be movable left and right. When vertical movement of the pressure rod 150 is required (e.g., when the pressure rod is inserted into the pouch case through the opening), the moving part 162 can move up and down along the support part 161. When horizontal movement of the pressure rod 150 is required (e.g., when the pressure rod is to pressurize the edge of the pouch case outward), the pressure rod 150 can move left and right along the moving part 162.

[0050] First, as shown in FIG. 7, a pair of pressure rods 150 can be inserted into the pouch case 110 through the opening 141 of the pouch case 110 formed by removing the first seal portion 131.

[0051] The pressure rod 150 may be inserted in a direction toward the electrode assembly 2 (e.g., downward in FIG. 7 ) until an inner end 151 of the pressure rod 150 facing the electrode assembly 2 is positioned adjacent to a position P where the main seal 134 (see FIG. 9 ) is formed. Here, the pressure rod 150 may not be inserted deeper into the pouch case 110 than the position P where the main seal 134 is formed. For example, the pressure rod 150 may be inserted only to a position that does not overlap with the position P where the main seal 134 is formed. The process of forming the main seal 134, which will be described later, may be performed while the pressure applied by the pressure rod 150 is maintained, but this is to prevent the pressure rod 150 from interfering with the process of forming the main seal 134.

[0052] Next, as shown in FIG. 8, the pressure rods 150 are moved away from each other (e.g., in the direction of the arrows in FIG. 8) to pressurize the second and third edges 122, 123 of the pouch case 110 toward the outside of the pouch case 110. This pressure can remove any wrinkles that may have formed in the pouch case 110. If this pressure is also applied during the formation of a main seal 134 (see FIG. 9), which will be described later, it can also prevent wrinkles from forming during the formation of the main seal 134. In this embodiment, since most of the second and third edges 122, 123 are directly pressed by the pressure rods 150, this is very effective in removing any existing wrinkles or preventing wrinkles from forming.

[0053] The second and third edges 122, 123 may be two edges of the edges of the pouch case 110 that pass through both ends of the main seal portion 134 in a direction across the main seal portion 134 (e.g., the vertical direction in FIG. 8) when the main seal portion 134 (see FIG. 9; see position P where the main seal portion is formed in FIG. 8) is formed. The second and third edges 122, 123 may be pressed against the outside of the pouch case 110 in the direction in which the main seal portion 134 is formed (e.g., the horizontal direction in FIG. 8). Since wrinkles may form in the pouch case 110 in the direction in which the main seal portion 134 is formed, as shown in the partially enlarged view of FIG. 4, pressing the edges of the pouch case 110 in the aforementioned direction is effective in removing the wrinkles.

[0054] Meanwhile, the pressure rods 150 may be inserted into the pouch case 110 and disposed parallel to the second and third edges 122 and 123, respectively, as shown in Fig. 7. For example, among the pressure rods 150, the left pressure rod 150L may be disposed parallel to the second edge 122, and the right pressure rod 150R may be disposed parallel to the third edge 123. Here, the pressure rods 150 may be disposed parallel to the second and third edges 122 and 123, respectively, and may move toward the second and third edges 122 and 123 so as to make at least line contact with the interior portions of the pouch case 110 corresponding to the second and third edges 122 and 123, as shown in Fig. 8.

[0055] For example, if the left end of the left pressure rod 150L is formed in a pointed shape, the left end of the left pressure rod 150L can come into line contact with the interior portion of the pouch case 110 where the second seal portion 132 is formed. If the left end of the left pressure rod 150L is formed in an arc shape, the left end of the left pressure rod 150L can also come into surface contact with the interior portion of the pouch case 110. In this way, the pressure rod 150 of this embodiment can come into contact with the interior portion of the pouch case 110 over as wide an area as possible. This is very effective in removing wrinkles that have occurred or preventing wrinkles from occurring.

[0056] After pressurizing the pouch case 110, a main seal 134 for separating and sealing the storage section 111 from the collecting section 112 can be formed between the storage section 111 and the collecting section 112, as shown in Fig. 9. The main seal 134 may be formed by heat sealing. If the main seal 134 is formed while the pouch case 110 is maintained under pressure, it is possible to prevent wrinkles from occurring during the process of forming the main seal 134.

[0057] Next, the collecting portion 112 can be cut out along the main seal portion 134 and outside the main seal portion 134. For example, the pouch case 110 can be cut along L2 in FIG. 9 to remove the collecting portion 112. This allows a pouch-type secondary battery to be manufactured. Pressurization by the pressure rod 150 can also be applied during this cutting process. The cutting process is stable when the pouch case 110 is cut while the second and third edges 122 and 123 of the pouch case 110 are supported by the pressure rod 150.

[0058] Meanwhile, pressure can be applied by the pressure rod 150 even during the discharge of the trapped gas. For example, if pressure is applied as shown in FIG. 8 during the discharge of the gas, it is possible to prevent the second and third edges 122 and 123 of the pouch case 110 from curling inward during the gas discharge, thereby preventing the pouch case 110 from becoming wrinkled. To expedite the gas discharge, the gas discharge may be performed in a vacuum atmosphere, but the curling of the second and third edges 122 and 123 may become more severe in a vacuum atmosphere. However, if the pressure rod 150 supports the second and third edges 122 and 123, the curling can be prevented.

[0059] Embodiment 2 10 is a diagram illustrating a manufacturing method of a secondary battery according to embodiment 2 of the present invention. The manufacturing method of embodiment 2 differs from the manufacturing method of embodiment 1 in the structure of the pressure rod. The manufacturing method of embodiment 2 will be described below, focusing on this point.

[0060] 5 to 9 can be similarly applied to the manufacturing method of embodiment 2. However, as shown in Fig. 10, in this embodiment, the structure of the pressure rod 250 used to pressurize the pouch case 110 differs from the above-described content.

[0061] The pressure rod of this embodiment will be described with reference to Figures 11 to 13. Figure 11 is a perspective view showing a pressure rod applied to the manufacturing method of Figure 10, Figure 12 is a cross-sectional view of the pressure rod of Figure 11 taken along line AA, and Figure 13 is a cross-sectional view of the pressure rod of Figure 11 taken along line BB. The pressure rod of Figure 11 shows the right pressure rod 250R of the pressure rod 250 of Figure 10.

[0062] The pressure rod 250 of this embodiment may have a portion whose thickness gradually decreases toward the side end facing the second edge 122 or the third edge 123 of the pouch case 110 that it presses, and whose thickness is thinnest at the side end. For example, the right pressure rod 250R in Fig. 10 may have a side end 252 facing the third edge 123 as shown in Fig. 11, and may have a portion whose thickness t2 gradually decreases toward the side end 252, and whose thickness t2 is thinnest at the side end 252 as shown in Fig. 12.

[0063] Because the edges of the pouch case 110 are joined, the space into which the pressure rod 250 is inserted narrows as it approaches the edges inside the pouch case 110. If the pressure rod 250 includes a portion where the thickness gradually decreases as described above, the pressure rod 250 can be easily inserted even in a narrow space.

[0064] Meanwhile, although FIG. 12 shows the right half of the right pressure rod 250R as having a shape that is thinner overall, the shape of the right pressure rod 250R is not limited to this. For example, the right half of the right pressure rod 250R may have a thinner thickness only in a portion adjacent to the side end 252. Also, although FIG. 12 shows the left half of the right pressure rod 250R as having a mirror image of the right half, the shape of the left half is not limited to this. For example, the left half may have a rectangular cross section. However, if the left half is formed in a mirror image of the right half, a single shaped pressure rod can be used as both the left and right pressure rods.

[0065] The pressure rod 250 of this embodiment may have a portion whose thickness gradually decreases toward the inner end 251 facing the electrode assembly 2, with the thickness being thinnest at the inner end 251. For example, the pressure rod 250 of FIG. 10 may have an inner end 251 facing the electrode assembly 2 as shown in FIG. 11 , and may have a portion whose thickness t1 gradually decreases toward the inner end 251, with the thickness t1 being thinnest at the inner end 251 as shown in FIG. 13 . As shown in FIG. 10 , the inner end 251 of the pressure rod 250 is inserted into the opening 141 first, and if the thickness gradually decreases toward the inner end 251, it becomes easier to insert the pressure rod 250 into the opening 141.

[0066] The above description merely exemplifies the technical concept of the present invention, and various modifications and variations may be made by a person having ordinary knowledge in the technical field to which the present invention pertains without departing from the essential characteristics of the present invention.

[0067] Therefore, the embodiments disclosed in the present invention are for illustrative purposes only and are not intended to limit the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by such embodiments.

[0068] The scope of protection of the present invention should be interpreted by the appended claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0069] 1. Pouch-type secondary battery 2 electrode assembly 15 Electrode tab 17 Electrode Lead 20 Exterior materials 21 Storage unit 23 Seal part 110 Pouch Case 111 Storage area 112 Collection unit 121~124 Edge 131 First seal part 132 Second seal part 133 Third seal part 134 Main seal part 150 Pressure Rod 151 Internal End 160 Drive Unit 161 Supporting Part 162 Moving Part 250 Pressure Rod 251 Internal End 252 Side end 310 Pouch Case 311 Storage section 312 Collection unit 331~333 Seal part 334 Main seal part 341 Gap

Claims

1. (a) preparing a pouch case having a storage section for storing an electrode assembly and a collection section communicating with the storage section and for collecting gas generated during a charge / discharge process for activation; (b) forming an opening in the collection section to discharge the gas collected in the collection section; (c) pressing at least a portion of the edge of the pouch case against the outside of the pouch case; (d) forming a main seal portion between the storage portion and the collection portion after pressurizing the pouch case or in a pressurized state, for separating and sealing the storage portion from the collection portion.

2. 2. The method for manufacturing a secondary battery according to claim 1, wherein the step (c) is a step of applying pressure to at least a part of the edge of the pouch case from the inside to the outside of the pouch case.

3. 2. The method for manufacturing a secondary battery according to claim 1, wherein step (c) is a step of pressing two edge portions of the pouch case that pass through both ends of the main seal portion in a direction that crosses the main seal portion when the main seal portion is formed, against the outside of the pouch case along the direction in which the main seal portion is formed.

4. 4. The method for manufacturing a secondary battery according to claim 1, wherein the pouch case includes: a first edge portion extending in a predetermined direction and disposed adjacent to the collecting portion; second and third edge portions extending from both ends of the first edge portion and positioned opposite each other; and a fourth edge portion connecting the second and third edge portions, positioned opposite the first edge portion, and disposed adjacent to the storage portion.

5. The method for manufacturing a secondary battery according to claim 4 , wherein the step (b) is a step of forming the opening by removing at least a part of a first sealing portion formed along the first edge portion.

6. The step (c) inserting a pair of pressure rods into the pouch case through the opening; and moving the pressure rods in directions away from each other to pressurize the second and third edges of the pouch case against the outside of the pouch case.

7. 7. The method of manufacturing a secondary battery according to claim 6, wherein the pressure rod is inserted in a direction toward the electrode assembly until an inner end of the pressure rod facing the electrode assembly is positioned adjacent to a position where the main seal portion is formed.

8. The method for manufacturing a secondary battery according to claim 7 , wherein the pressure rod is not inserted into the pouch case beyond a position where the main seal portion is formed.

9. The method of manufacturing a secondary battery according to claim 6 , wherein the pressure rods are inserted into the pouch case and arranged parallel to the second and third edges, respectively.

10. 10. The method for manufacturing a secondary battery according to claim 9, wherein the pressure rod is disposed parallel to the second and third edges, respectively, and moves toward the second and third edges so as to make at least line contact with internal portions of the pouch case corresponding to the second and third edges.

11. Each of the pair of pressure rods is 7. The method for manufacturing a secondary battery according to claim 6, wherein the thickness gradually decreases toward a side end facing the second edge or the third edge that the sheet itself presses, and the side end includes a portion where the thickness is thinnest.

12. Each of the pair of pressure rods is The method of manufacturing a secondary battery according to claim 6 , wherein the thickness gradually decreases toward the inner end facing the electrode assembly, and the inner end includes a portion where the thickness is thinnest.

13. The method for manufacturing a secondary battery according to claim 1 , further comprising the step of cutting off the collection portion along the main seal portion and outside the main seal portion.

14. The method for manufacturing a secondary battery according to claim 13 , wherein the collection portion is cut while the pouch case is being pressed.

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