Secondary battery and method for manufacturing same

Abstract

The method for manufacturing a secondary battery according to various embodiments may comprise the steps of: preparing at least one pouch sheet having a masking tape attached thereto; placing an electrode assembly inside a battery case formed by overlapping the at least one pouch sheet; injecting an electrolyte into the battery case and sealing the edge of the battery case; performing formation with regard to the secondary battery; cutting a partial region of the battery case, removing the masking tape, and degassing same; and resealing the region corresponding to the removed masking tape. Other additional embodiments are possible.

Description

Secondary battery and method for manufacturing the same

[0001] Various embodiments of the present disclosure relate to a secondary battery and a method for manufacturing the same, and a pouch sheet used in manufacturing the secondary battery.

[0002] Secondary batteries, capable of being recharged and discharged, are widely used in portable mobile devices such as digital cameras, mobile phones, and laptops. In particular, with the rapid development of the electrical, electronics, communications, and computer industries, demand for high-performance, high-stability secondary batteries is steadily increasing.

[0003] In particular, pouch-type secondary batteries have an exterior made of a pouch outer material composed of a multilayer film of a metal layer (foil) and a synthetic resin layer coated on the upper and lower surfaces of the metal layer, and thus, compared to cylindrical or square secondary batteries using metal cans, they have the advantage of being significantly lighter, lighter, and can be transformed into various shapes, and thus, they are receiving a lot of attention and various developments are being carried out accordingly.

[0004] Meanwhile, liquid electrolytes are widely used in secondary batteries, but liquid electrolytes have the problem of leakage and solvent volatility and instability. Accordingly, various studies are being conducted recently to commercialize polymer electrolytes, such as gel polymer electrolytes, as electrolytes to replace liquid electrolytes.

[0005] Gel polymer electrolytes are attracting attention because they offer superior electrochemical safety compared to liquid electrolytes and can maintain a constant thickness of the battery.

[0006] However, when a secondary battery is manufactured using a conventional manufacturing method by applying a gel polymer electrolyte, problems such as complete sealing not being achieved during the resealing process or the gelled electrolyte forming stains on the outside, which detracts from the aesthetic appeal, may become particularly noticeable, depending on the characteristics of the gel polymer electrolyte.

[0007] Various embodiments of the present disclosure have been devised to solve at least some of the problems of the prior art as described above, and provide a manufacturing method capable of effectively preventing electrolyte from remaining in a resealing area during the manufacturing process of a secondary battery through a simple method using a pouch sheet to which a masking tape is attached, a secondary battery manufactured thereby, and a pouch sheet used in the manufacturing of the secondary battery.

[0008] According to various embodiments of the present disclosure, a method for manufacturing a secondary battery may include: preparing at least one pouch sheet having a masking tape attached thereto; accommodating an electrode assembly inside a battery case formed by overlapping at least one pouch sheet; injecting an electrolyte into the inside of the battery case and sealing an edge of the battery case; performing a formation on a secondary battery; cutting a portion of the battery case, and then removing and degassing the masking tape; and performing a resealing on an area corresponding to the removed masking tape.

[0009] A pouch sheet for manufacturing a battery case of a secondary battery according to various embodiments includes a concave portion for accommodating an electrode assembly; and a masking tape detachably attached to one side adjacent to the concave portion, wherein the masking tape can extend along the length direction of an area to be resealed so as to at least partially correspond to an area to be resealed during the manufacturing process of the secondary battery.

[0010] According to various embodiments of the present disclosure, it is possible to effectively prevent various problems that may arise due to improper sealing in the resealing area of ​​a secondary battery by preventing electrolyte from remaining in the resealing area, such as shortening of the battery life due to oxygen or moisture entering the case of the secondary battery.

[0011] In addition, it can prevent external defects in secondary batteries and improve aesthetics.

[0012] FIG. 1 is a schematic exploded perspective view of a secondary battery according to one embodiment of the present disclosure.

[0013] FIG. 2A is a front view of a pouch sheet used in manufacturing a secondary battery case according to one embodiment of the present disclosure.

[0014] Figure 2b is a side cross-sectional view of the pouch sheet of Figure 2a cut along line AA.

[0015] Figure 2c is a side cross-sectional view of the pouch sheet of Figure 2a cut along line BB.

[0016] FIG. 3 is a schematic front view of a pouch sheet for forming a case of a secondary battery according to one embodiment of the present disclosure.

[0017] FIG. 4 is a schematic front view illustrating a sealing area and a resealing area in a pouch sheet according to one embodiment of the present disclosure.

[0018] FIG. 5 is a schematic side view illustrating a sealing area and a resealing area in a pouch sheet according to one embodiment of the present disclosure.

[0019] FIG. 6 is a schematic front view of a pouch sheet for explaining an area where a masking tape is attached in the pouch sheet according to one embodiment of the present disclosure.

[0020] FIG. 7 is a schematic side view of a pouch sheet for explaining an area where a masking tape is attached in the pouch sheet according to one embodiment of the present disclosure.

[0021] FIG. 8A is a schematic front view of a pouch sheet for explaining an area where a masking tape is attached in the pouch sheet according to one embodiment of the present disclosure.

[0022] Figure 8b is a drawing schematically showing the shape of a masking tape attached to the pouch sheet of Figure 8a.

[0023] Figure 9 is an image taken of the periphery of the resealing area of ​​a secondary battery manufactured using a manufacturing method according to a comparative example.

[0024] FIG. 10 is an image taken of the periphery of a resealing area of ​​a secondary battery manufactured using a manufacturing method according to one embodiment of the present disclosure.

[0025] Before going into the detailed description of the present invention, it should be noted that the terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted with meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term in order to explain his own invention in the best way. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical idea of ​​the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of this application.

[0026] The same reference numbers or symbols used in each drawing attached to this specification represent parts or components that perform substantially the same functions. For convenience of explanation and understanding, the same reference numbers or symbols may be used in different embodiments. In other words, even if components with the same reference numbers are depicted in multiple drawings, they do not necessarily represent a single embodiment.

[0027] In the following description, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms such as "comprises" or "comprises" should be understood to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0028] In addition, in the description below, expressions such as top, upper, lower, lower, side, front, and rear are expressed based on the direction shown in the drawing, and it is noted in advance that they may be expressed differently if the direction of the object in question changes.

[0029] Additionally, terms including ordinal numbers, such as "first," "second," etc., may be used in this specification and claims to distinguish between components. These ordinal numbers are used to distinguish identical or similar components from each other, and the use of these ordinal numbers should not be interpreted in a limited manner. For example, components associated with these ordinals should not be interpreted in a restricted manner, such as in the order of use or arrangement, based on their numbers. If necessary, each ordinal number may be used interchangeably.

[0030] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. However, the spirit of the present invention is not limited to the presented embodiments. For example, those skilled in the art who understand the spirit of the present invention may propose other embodiments within the spirit of the present invention by adding, modifying, or deleting components, etc., but such embodiments will also be considered to be within the spirit of the present invention. The shapes and sizes of elements in the drawings may be exaggerated for clarity.

[0031] FIG. 1 is a schematic exploded perspective view of a secondary battery (100) according to one embodiment of the present disclosure.

[0032] FIG. 2a is a front view of a pouch sheet (110) used in the manufacture of a secondary battery case according to one embodiment of the present disclosure. FIG. 2b is a side cross-sectional view of the pouch sheet (110) of FIG. 2a when cut along line AA. FIG. 2c is a side cross-sectional view of the pouch sheet (110) of FIG. 2a when cut along line BB.

[0033] Referring to FIGS. 1 to 2C, a secondary battery (100) according to various embodiments may include an electrode assembly (200) and a battery case (50) that accommodates the electrode assembly (200).

[0034] According to various embodiments, the electrode assembly (200) may include a plurality of electrodes (220), an electrode tab (230) extending from at least one of the plurality of electrodes (220), and a separator interposed between the plurality of electrodes (220). The plurality of electrodes (220) may be composed of an anode and a cathode, and for example, the electrode assembly (200) may have a structure in which an anode, a separator, and a cathode are sequentially stacked.

[0035] The negative electrode may include a negative electrode current collector and a negative electrode active material laminated on the negative electrode current collector. For example, the negative electrode may be formed by applying a mixture including at least a negative electrode active material, a conductive material, and a binder to a negative electrode current collector formed of a material such as a copper alloy. Meanwhile, in an embodiment, the negative electrode may be formed of an integrated lithium metal sheet, instead of separately providing the negative electrode current collector and the negative electrode active material. The lithium metal sheet is a flat sheet member made of lithium metal (lithium or an alloy material including lithium). For example, the negative electrode and the negative electrode tab extending from an end of the negative electrode may both be formed of lithium metal as an integrated body.

[0036] The positive electrode may include a positive electrode current collector and a positive electrode active material laminated on the positive electrode current collector. For example, the positive electrode may be formed by applying a mixture including at least a positive electrode active material, a conductive material, and a binder to a positive electrode current collector formed of a material such as an aluminum alloy. For example, the positive electrode active material may be composed of lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a compound or mixture containing one or more of these. As another example, a sulfur-based material having an SS bond may be used as the positive electrode active material.

[0037] The separator may be configured to prevent electrical short-circuiting between electrodes and to be impregnated with an electrolyte to allow ion passage. For example, the separator may be formed of a porous polymer film or a porous nonwoven fabric. However, the separator applied to the secondary battery according to various embodiments of the present disclosure is not necessarily limited to the above materials, and various materials commonly applied in secondary batteries may be used.

[0038] The electrode tab (230) may include a positive tab extending from an end of the positive electrode and a negative tab extending from an end of the negative electrode. The electrode tab (230) may be electrically connected to an electrode lead (240) that serves as a terminal in the secondary battery (100). For example, the positive tab may be formed of an aluminum (Al) material, and the negative tab may be formed of a copper (Cu) or lithium (Li) material.

[0039] In various embodiments, the secondary battery (100) may include a unidirectional secondary battery in which the positive and negative tabs of the electrode tabs (230) extend in the same direction, or a bidirectional secondary battery in which the positive and negative tabs extend in opposite directions. For example, various embodiments of the present disclosure may be applied to a unidirectional secondary battery such as that illustrated in FIG. 1, but may also be applied to a bidirectional secondary battery such as that illustrated in FIG. 4.

[0040] The electrode lead (240) may be electrically connected to the electrode assembly (200) (e.g., the electrode tab (230) of the electrode assembly (200). For example, the electrode lead (240) may include a positive lead connected to a positive tab extending from the positive electrode, and a negative lead electrically connected to a negative tab extending from the negative electrode. For this purpose, the electrode lead (240) may be formed of a conductive metal material. For example, the electrode lead (240) may be formed of at least one of nickel, copper, nickel-plated copper, and aluminum. The electrode lead (240) and the electrode tab (230) may be electrically connected through various welding methods including ultrasonic welding, but a physical fastening method using a rivet, etc. may also be applied.

[0041] For example, an insulating member (245) may be placed in one area of ​​the electrode lead (240). For example, the insulating member (245) may be formed of a material having insulating and adhesive properties (e.g., a thermoplastic resin), and may be bonded to a portion of the battery case (50) while wrapping a portion of the electrode lead (240), thereby ensuring electrical insulation between the electrode lead (240) and the battery case (50). The insulating member (245) may seal the battery case (50) in an area where the electrode lead (240) protrudes from the inside to the outside of the battery case (50), and may serve as a buffer to prevent damage that may occur to the electrode lead (240) during the sealing process of the battery case (50).

[0042] The battery case (50) may include a receiving portion (150), which is an internal space in which the electrode assembly (200) can be received, and a sealing portion (170), which is an area sealed to shield the electrode assembly (200) at least at a portion of the edge of the receiving portion (150).

[0043] Meanwhile, the battery case (50) can be formed by combining an upper case (52) and a lower case (54). The upper case (52) and the lower case (54) can be mutually combined, for example, by a compression or heat-sealing method in the sealing portion (170) area, thereby preventing external foreign substances or moisture from entering the electrode assembly (200) disposed inside the receiving portion (150).

[0044] For example, the battery case (50) may be formed by at least one pouch sheet (110) made of a flexible material (e.g., an aluminum laminate sheet). This pouch sheet (110) may be processed to include a concave portion on the inside to form a receiving portion (150), which is a space for receiving the electrode assembly (200). The concave portion formed in the pouch sheet (110) may be provided to correspond to the shape and size of the electrode assembly (200).

[0045] Meanwhile, in FIG. 1, only the lower case (54) is illustrated as including a concave shape for forming a receiving portion (150), and the upper case (52) is illustrated as not including a separate concave shape structure. However, in various embodiments of the present disclosure, the upper case (52) may also include a concave shape forming a receiving portion (150) just like the lower case (54), and it may be understood that a single receiving portion (150) is implemented by combining the upper case (52) and the lower case (54). For example, the upper case (52) and the lower case (54) may have a substantially symmetrical structure, and may be formed by a pouch sheet (110) including a concave portion (112) as illustrated in FIGS. 2A to 2C, respectively. In addition, unlike this, as illustrated in FIG. 1, it is of course possible that the upper case (52) is not provided with a concave shape, and only the lower case (54) is provided with a concave shape.

[0046] FIGS. 3 to 5 are drawings for explaining a method for manufacturing a secondary battery (100) according to one embodiment of the present disclosure. Specifically, FIG. 3 is a schematic front view of a pouch sheet (110) for forming a case (50) of a secondary battery (100) according to one embodiment of the present disclosure. FIGS. 4 and 5 are schematic front and side views, respectively, for explaining a sealing area (310) and a resealing area (320) in a pouch sheet (110) of a secondary battery (100) according to one embodiment of the present disclosure.

[0047] Referring to FIGS. 3 to 5, a battery case (50) of a secondary battery (100) according to various embodiments can be manufactured using at least one pouch sheet (110).

[0048] For example, the case (50) of the secondary battery (100) can be formed by placing the electrode assembly (200) between two pouch sheets (110) and joining the peripheral portion where the electrode assembly (200) is placed by sealing or resealing. Meanwhile, the two pouch sheets (110) can each include a concave portion (112), and when the two pouch sheets (110) are joined, a receiving portion (150) space in which the electrode assembly (200) is accommodated can be formed in the inner space of the two concave portions (112). For example, the two pouch sheets (110) may be substantially symmetrical or have the same structure.

[0049] Although not shown, in another example, the case (50) of the secondary battery (100) may be formed by folding a single pouch sheet (110) so that both ends overlap each other, placing the electrode assembly (200) inside the folded portion, and then bonding the open end so that the electrode assembly (200) is sealed inside.

[0050] Meanwhile, in the manufacturing process of a secondary battery (100), after two pouch sheets (110) are overlapped to form a battery case (50) and an electrode assembly (200) is accommodated inside, a step of injecting an electrolyte into the inside of the battery case (50) and sealing the edge of the battery case (50) may be performed.

[0051] In particular, the sealing work may be performed in the following order: first sealing the remaining area except for one edge among the multiple edges forming the edge sealing area (310) of the battery case (50), injecting the electrolyte through the unsealed edge, and then sealing the unsealed edge as well. At this time, the last edge of the battery case (50) to be sealed, that is, the edge into which the electrolyte is injected, may correspond to an edge that is relatively far from the edge where the concave portion (112) is formed in the pouch sheet (110) (for example, the right edge of the sealing area (310) of the pouch sheet (110) illustrated in FIG. 4).

[0052] Next, after the entire edge of the battery case (50), which is the sealing area (310), is sealed, formation can be performed on the secondary battery (100). The formation is a process of forming an SEI layer (Solid Electrolyte Interphase layer) on the surface of the electrodes (220) of the electrode assembly (200) through a charging process and charging the electrodes, thereby allowing the secondary battery (100) to be charged so as to supply power.

[0053] Meanwhile, in various embodiments of the present disclosure, the electrolyte applied to the secondary battery (100) may include a gel polymer electrolyte. Compared to a typical liquid electrolyte, the gel polymer electrolyte may have the advantage of maintaining a constant thickness of the battery and of being able to manufacture a thin-film battery with excellent electrical and chemical safety due to the inherent adhesive strength of the gel phase.

[0054] In this way, when the electrolyte applied to the secondary battery (100) is a gel polymer electrolyte, a curing process may be further performed to gel the liquid gel polymer electrolyte. In the method for manufacturing a secondary battery according to one embodiment of the present disclosure, the curing process may be performed immediately before performing formation. However, the manufacturing order is not limited thereto, and in other embodiments, the curing process for gelation may be performed after performing formation, depending on the case.

[0055] Next, after curing and forming the secondary battery (100) are performed, a cutting operation may be performed to cut a portion of the sealed battery case (50) for degassing. For example, a cutting operation may be performed on the case (50) of the secondary battery (100) along the CC line of the pouch sheet (110) illustrated in FIGS. 3 and 4 .

[0056] After that, the packaging process of the secondary battery (100) can be completed after degassing and resealing operations are performed under vacuum conditions. At this time, the resealing (i.e., resealing) operation can be performed in the resealing area (320) illustrated in FIGS. 4 and 5. The resealing area (320) can include at least a portion of an area opened by a cutting operation performed along the CC line among the periphery of the edge of the concave portion (112) inside the case (50) where the electrode assembly (200) of the secondary battery (100) is placed (i.e., an area corresponding to the sealing portion (170) of the battery case (50). For example, as illustrated in FIG. 4, the resealing area (320) may be an area that extends in the x-axis direction among the areas open in the direction toward the CC line in the concave portion (112) and overlaps with the sealing area (310), and in particular, may be an area adjacent to the concave portion (112).

[0057] Meanwhile, when manufacturing a secondary battery (100) according to the process sequence described above, the electrolyte may get on the resealing area (320) during the electrolyte injection process, which may prevent proper sealing in the resealing area (320), potentially allowing oxygen or moisture to enter the electrode assembly (200) inside the battery case (50), and a problem of deteriorating the appearance of the secondary battery (100) may also occur. In particular, when a gel polymer electrolyte is used, the electrolyte may harden during the curing process, resulting in the electrolyte remaining in the form of a jelly in the resealing area (320), which may further increase the possibility of improper sealing or appearance defects.

[0058] Accordingly, in the secondary battery (100) according to various embodiments of the present disclosure, a masking tape is attached in advance to a portion of a pouch sheet (110) forming a battery case (50), and after a predetermined process is performed, the battery case (50) is cut for degassing, and the attached masking tape on which the electrolyte is present is removed, and after removing the masking tape, a degassing and resealing process is performed, thereby preventing the electrolyte from being present in a predetermined area where the masking tape was attached, thereby preventing the occurrence of defects caused by the electrolyte as described above.

[0059] FIG. 6 and FIG. 7 are schematic front and side views of a pouch sheet (110) for explaining an area (330) where a masking tape is attached in the pouch sheet (110) forming a battery case (50) of a secondary battery (100) according to one embodiment of the present disclosure.

[0060] To form a battery case (50), each of the two facing pouch sheets (110) may have a masking tape pre-attached to an area (330) corresponding to at least a portion of the resealing area (320).

[0061] At this time, in order to prevent the sealing area (310) from being unsealed due to the masking tape or the sealing of the sealing area (310) from being disabled when the masking tape is removed, the masking tape may not be attached to the area where the resealing area (320) and the sealing area (310) overlap.

[0062] Meanwhile, the area (330) where the masking tape is attached in advance in the pouch sheet (110) may have a larger margin area than the area excluding the sealing area (310) among the resealing areas (320).

[0063] For example, the width of the area (330) where the masking tape is attached can be set to be equal to or larger than the width of the resealing area (320), thereby more reliably preventing the electrolyte from being deposited on the resealing area (320).

[0064] In an embodiment, the masking tape may be attached to the inner surface of each of two overlapping pouch sheets (110). The masking tape is in the form of a film with an adhesive layer formed on only one surface, and the masking tape may be attached to the pouch sheet (110) by the adhesive layer.

[0065] Masking tapes can be attached to each of two pouch sheets (110). The non-adhesive film sides of each of the masking tapes attached to the two pouch sheets (110) can face each other, and the electrolyte can be injected between the two film sides of each masking tape.

[0066] Meanwhile, each masking tape may be removed after accommodating the electrode assembly (200) in the recess (112) between the two pouch sheets (110), injecting the electrolyte, sealing the sealing area (310), optionally curing the electrolyte, forming the secondary battery (100), and performing a cutting operation along the CC line for degassing. In addition, after removing the masking tape in this manner, degassing and resealing operations may be performed in a vacuum.

[0067] For example, when applying a gel polymer electrolyte, since the electrolyte is already hardened as the curing process is performed in the step prior to the cutting process, even if the battery case (50) is cut and the masking tape is removed from the inner surface of each pouch sheet (110), the electrolyte may no longer be transferred to the resealing area (320).

[0068] FIG. 8a is a schematic front view illustrating an area (330) to which a masking tape is attached in a pouch sheet (110) of a secondary battery (100) according to another embodiment of the present disclosure. FIG. 8b is a drawing illustrating a schematic shape of a masking tape attached to the pouch sheet (110) of FIG. 8a.

[0069] Referring to FIGS. 8A and 8B, in the manufacturing process of a secondary battery (100) according to various embodiments, a masking tape pre-attached to a pouch sheet (110) for forming a battery case (50) may include a resealing portion (432) corresponding to a resealing area (320) and an extension portion (435) formed to extend in one direction from the resealing portion (432).

[0070] The resealing portion (432) may be attached to a first region (332) corresponding to a region of the resealing region (320) of the pouch sheet (110) excluding the sealing region (310). The extension portion (435) may have a shape extending in the Y-axis direction from one side (or multiple sides) of the first region (332), and may be located, for example, in a second region (335) that does not correspond to the resealing region (320).

[0071] By masking the pouch sheet (110) using a masking tape that further includes an extension portion (435) formed by extending from the resealing portion (432), the worker can easily remove the masking tape while holding the extension portion (435) during the process of removing the masking tape after the pre-cutting operation for degassing.

[0072] The resealing portion (432) and the extension portion (435) of the masking tape may be formed as an integral body, but the adhesive layer of the masking tape may be formed only on the resealing portion (432). For example, the extension portion (435) of the masking tape may not have adhesive strength on both sides of the film layer constituting the masking tape. However, this is not limited to this embodiment, and an adhesive layer may be formed on each of the resealing portion (430) and the extension portion (435).

[0073] Meanwhile, in various embodiments of the present disclosure, the number and positions of the extension portions (435) of the masking tape and the second areas (335) on the pouch sheet (110) where the extension portions (435) are positioned are not limited to those illustrated in FIGS. 8A and 8B. For example, the extension portions (435) may be formed to extend from each end of the resealing portion (432), or may be formed to extend from each end and the center of the resealing portion (432), and various other modified structures may also be applied.

[0074] FIG. 9 is an image of the periphery of the resealing area (320) of a secondary battery (100) manufactured without attaching masking tape using a manufacturing method according to a comparative example, and FIG. 10 is an image of the periphery of the resealing area (320) of a secondary battery (100) manufactured using masking tape using a manufacturing method according to an embodiment of the present disclosure.

[0075] Referring to FIGS. 9 and 10, in the comparative example of FIG. 9 where no masking tape was used, it can be confirmed with the naked eye that electrolyte remains on the pouch sheet (110) around the resealing area (320) and stains occur, but in the case of the result according to the embodiment of FIG. 10 where masking tape was used, it can be confirmed that no electrolyte remains on the pouch sheet (110) around the resealing area (320), and thus no appearance defects occur.

[0076] Meanwhile, although terms indicating directions such as up and down are used in this specification, it is obvious to those skilled in the art that these terms are only for convenience of explanation and may vary depending on the location of the target object or the location of the observer.

[0077] While various embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it will be apparent to those skilled in the art that various modifications and variations are possible without departing from the technical spirit of the present invention as set forth in the claims. Furthermore, the embodiments described above may be implemented by deleting some components, and the embodiments may be implemented in combination with each other.

Claims

1. In a method for manufacturing a secondary battery, A step of preparing at least one pouch sheet with masking tape attached; A step of accommodating an electrode assembly inside a battery case formed by overlapping at least one of the above pouch sheets; A step of injecting electrolyte into the inside of the battery case and sealing the edge of the battery case; A step of performing formation on the above secondary battery; After cutting out a portion of the battery case, the step of removing the masking tape and degassing; and A method for manufacturing a secondary battery, comprising the step of performing resealing on an area corresponding to the removed masking tape.

2. In paragraph 1, The area of ​​the above pouch sheet to which the masking tape is attached is, At least partially comprising a re-ceiling area in which the re-ceiling is performed; A method for manufacturing a secondary battery, excluding a sealing area in which the above sealing is performed.

3. In paragraph 1, The above masking tape, A resealing section corresponding to a resealing area where the above resealing is performed; and A method for manufacturing a secondary battery, comprising an extension portion formed to extend in one direction from the above-mentioned resealing portion.

4. In paragraph 3, A method for manufacturing a secondary battery, wherein the extension does not include an adhesive layer.

5. In paragraph 1, The above electrolyte comprises a gel electrolyte, A method for manufacturing a secondary battery, further comprising a step of performing a curing process to gel the gel electrolyte prior to performing the formation.

6. In paragraph 1, The step of sealing the edge of the above battery case is: A step of sealing some of the open edges of the above battery case; and A method for manufacturing a secondary battery, comprising the step of sealing a remaining portion of the open edge after injecting an electrolyte into the inside of the battery case.

7. In a pouch sheet for manufacturing a battery case of a secondary battery, The above pouch sheet, a recess for accommodating an electrode assembly; and Including a masking tape detachably attached to one side adjacent to the above concave portion, The above masking tape is a pouch sheet that extends along the length direction of the area to be resealed so as to at least partially correspond to the area to be resealed during the manufacturing process of the secondary battery.

8. In paragraph 7, The above masking tape, A resealing portion corresponding to the above resealing area; and A pouch sheet including an extension portion formed to extend in a direction other than the longitudinal direction from the above-described resealing portion.

9. In paragraph 8, The above resealing portion includes an adhesive layer, A pouch sheet, wherein the above extension does not include an adhesive layer.

10. In paragraph 7, The above masking tape, A pouch sheet that is removed prior to the degassing process after the cutting process for degassing during the manufacturing process of a secondary battery.

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