Secondary battery and method for manufacturing the same

Abstract

This simple method, which uses a pouch sheet with masking tape attached, effectively prevents electrolyte from remaining in the resealed area during the manufacturing process of secondary batteries. [Solution] A method for manufacturing a secondary battery may include the steps of: preparing at least one pouch sheet with masking tape attached; housing an electrode assembly inside a battery case formed by stacking the at least one pouch sheet; injecting an electrolyte into the battery case and sealing the ends of the battery case; performing a formation on the secondary battery; cutting open a portion of the battery case, removing the masking tape and degassing it; and resealing the area corresponding to the removed masking tape. Other embodiments are also possible.

Description

Technical Field

[0001] Various embodiments of the present disclosure relate to secondary batteries, methods for manufacturing the same, and pouch sheets used in the manufacture of secondary batteries.

Background Art

[0002] Secondary batteries can be charged and discharged and are widely used in portable mobile devices such as digital cameras, mobile phones, and laptop computers. In particular, recently, with the rapid development of the electric, electronic, communication, and computer industries, the demand for high-performance and high-stability secondary batteries has been gradually increasing.

[0003] In particular, a pouch-type secondary battery uses a pouch exterior material composed of a multilayer film of a metal layer (foil) and synthetic resin layers coated on the upper and lower surfaces of the metal layer to form its appearance. Compared with cylindrical or prismatic secondary batteries using metal cans, it has the advantages of significantly reducing weight, being able to achieve weight reduction, and being deformable into various forms, attracting much attention, and various developments have been carried out accordingly.

[0004] On the other hand, generally, liquid electrolytes are widely used in secondary batteries. However, in the case of liquid electrolytes, there is a possibility of leakage, and there are problems such as the volatility and instability characteristics of the solvent. Accordingly, recently, various studies have been carried out to commercialize polymer electrolytes such as gel polymer electrolytes as electrolytes to replace liquid electrolytes.

[0005] Gel polymer electrolytes have attracted attention because they are superior in electrochemical stability compared to liquid electrolytes and can maintain the thickness of the battery constant.

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when using gel polymer electrolytes to manufacture secondary batteries using conventional manufacturing methods, the properties of the gel polymer electrolyte can lead to particularly noticeable problems such as incomplete sealing during the resealing process, or the gelled electrolyte forming stains that detract from the aesthetic appearance.

[0007] Various embodiments of this disclosure have been devised to solve at least some of the problems of the prior art described above, and provide a manufacturing method that can effectively prevent electrolyte from remaining in the resealed area during the manufacturing process of a secondary battery by using a pouch sheet to which masking tape has been attached, a secondary battery manufactured thereby, and a pouch sheet used in the manufacture of a secondary battery. [Means for solving the problem]

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

[0009] A pouch sheet for manufacturing a battery case for a secondary battery according to various embodiments includes a recess for housing an electrode assembly and a masking tape detachably attached to one side adjacent to the recess, the masking tape being extended along the length 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. [Effects of the Invention]

[0010] According to various embodiments of this disclosure, it is possible to prevent electrolyte residue from remaining in the resealed area of ​​a secondary battery and effectively prevent various problems that may occur due to insufficient sealing in the resealed area, such as the shortening of battery life due to the inflow of oxygen and moisture into the case of the secondary battery. Furthermore, it is possible to prevent cosmetic defects of the secondary battery and improve its aesthetic appearance. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic exploded perspective view of a secondary battery according to one embodiment of the present disclosure. [Figure 2a] This is a front view of a pouch sheet used in the manufacture of a secondary battery case according to one embodiment of the present disclosure. [Figure 2b] This is a side cross-sectional view of the pouch sheet shown in Figure 2a, when it has been cut along the AA line. [Figure 2c] This is a side cross-sectional view of the pouch sheet shown in Figure 2a, when it has been cut along the BB line. [Figure 3] This is a schematic front view of a pouch sheet for forming a case for a secondary battery according to one embodiment of the present disclosure. [Figure 4] This is a schematic front view illustrating the sealing area and the resealing area in a pouch sheet according to one embodiment of the present disclosure. [Figure 5] This is a schematic side view illustrating the sealing area and the resealing area in a pouch sheet according to one embodiment of the present disclosure. [Figure 6] This is a schematic front view of a pouch sheet illustrating the area to which masking tape is applied in a pouch sheet according to one embodiment of the present disclosure. [Figure 7] This is a schematic side view of a pouch sheet illustrating the area to which masking tape is applied in a pouch sheet according to one embodiment of the present disclosure. [Figure 8a] This is a schematic front view of a pouch sheet illustrating the area to which masking tape is applied in a pouch sheet according to one embodiment of the present disclosure. [Figure 8b] Figure 8a shows the approximate shape of the masking tape that will be attached to the pouch sheet. [Figure 9] This is an image of the peripheral area of ​​the resealed region of a secondary battery manufactured using a comparative manufacturing method. [Figure 10] This is an image of the peripheral area of ​​the resealed region of a secondary battery manufactured by the manufacturing method according to one embodiment of this disclosure. [Modes for carrying out the invention]

[0012] Prior to a detailed description of the present invention, terms and words used herein and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, based on the principle that inventors can appropriately define terms as concepts in order to best describe their invention. Accordingly, the embodiments described herein and the configurations illustrated in the drawings represent only the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention; therefore, it should be understood that, at the time of filing, there may be a variety of equivalents and variations that can be substituted therefor.

[0013] The same reference numerals or symbols in the drawings attached to this specification indicate parts or components that perform substantially the same function. For the sake of explanation and understanding, different embodiments may also be described using the same reference numerals or symbols. That is, even if multiple drawings illustrate components with the same reference numerals, not all of the drawings necessarily represent a single embodiment.

[0014] In the following description, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms such as "including" or "comprising" are intended to specify that there are features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should not be construed as precluding the presence or addition of one or more different features, numbers, steps, operations, components, parts, or combinations thereof.

[0015] Also, in the following description, expressions such as upper side, upper part, lower side, lower part, side surface, front surface, and rear surface are represented based on the directions shown in the drawings, and it is clearly stated in advance that they may be represented differently if the direction of the corresponding object is changed.

[0016] Also, in this specification and the claims, terms including ordinal numbers such as "first", "second", etc. may be used for the purpose of distinguishing between components. Such ordinal numbers are used to distinguish the same or similar components from each other, and the meaning of the terms should not be limitedly construed by the use of such ordinal numbers. As an example, the components combined with such ordinal numbers should not be limitedly construed by their numbers in terms of the order of use or the order of arrangement, etc. If necessary, each ordinal number may be used alternately with each other.

[0017] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the idea of the present invention is not limited to the presented embodiments. For example, those skilled in the art who understand the idea of the present invention can propose other embodiments included within the scope of the idea of the present invention through the addition, modification, or deletion of components, etc., and these will also be included within the scope of the idea of the present invention. In the drawings, the shapes and sizes of elements may be exaggerated for clearer explanation.

[0018] FIG. 1 is a schematic exploded perspective view of a secondary battery 100 according to an embodiment of the present disclosure.

[0019] Figure 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. Figure 2b is a side cross-sectional view of the pouch sheet 110 in Figure 2a when cut along line AA. Figure 2c is a side cross-sectional view of the pouch sheet 110 in Figure 2a when cut along line BB.

[0020] Referring to Figures 1 to 2c, the secondary battery 100 in various embodiments may include an electrode assembly 200 and a battery case 50 that receives the electrode assembly 200.

[0021] 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 separation membrane interposed between the plurality of electrodes 220. The plurality of electrodes 220 may consist of positive electrodes and negative electrodes, and for example, the electrode assembly 200 may have a structure in which the positive electrode, separation membrane, and negative electrode are sequentially stacked.

[0022] 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 coating a negative electrode current collector, which is made of a material such as a copper alloy, with a mixture containing at least a negative electrode active material, a conductive material, and a binder. On the other hand, in an embodiment, the negative electrode may consist of an integrated lithium metal sheet instead of separately comprising a negative electrode current collector and a negative electrode active material. The lithium metal sheet is a flat sheet member made of lithium metal (lithium or a lithium-containing alloy material), and for example, the negative electrode and the negative electrode tabs extending from the ends of the negative electrode may all be made of lithium metal as an integrated unit.

[0023] 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 coating a positive electrode current collector, which is made of a material such as an aluminum alloy, with a mixture containing at least a positive electrode active material, a conductive material, and a binder. For example, the positive electrode active material may consist 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 with SS bonds may be used as the positive electrode active material.

[0024] The separation membrane may not only prevent electrical short circuits between electrodes, but may also be configured to be impregnated with an electrolyte and allow ions to pass through. Exemplarily, the separation membrane may be formed from a porous polymer film or a porous nonwoven fabric. However, the separation membranes applied to secondary batteries according to various embodiments of this disclosure are not necessarily limited to the aforementioned materials, and a variety of materials commonly used in secondary batteries may be used.

[0025] The electrode tabs 230 may include a positive electrode tab extending from the positive electrode end and a negative electrode tab extending from the negative electrode end. The electrode tabs 230 may be electrically connected to electrode leads 240 that act as terminals in the secondary battery 100. For example, the positive electrode tab may be formed from aluminum (Al) material, and the negative electrode tab may be formed from copper (Cu) or lithium (Li) material.

[0026] In various embodiments, the secondary battery 100 may include a unidirectional secondary battery in which the positive and negative electrode tabs of the electrode tabs 230 extend in the same direction, or a bidirectional secondary battery in which the positive and negative electrode tabs extend in opposite directions. For example, various embodiments of the present disclosure may be applied to a unidirectional secondary battery as shown in Figure 1, but may also be applied to a bidirectional secondary battery as shown in Figure 4.

[0027] The electrode leads 240 can be electrically connected to the electrode assembly 200 (e.g., the electrode tabs 230 of the electrode assembly 200). For example, the electrode leads 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 leads 240 may be formed from a conductive metallic material. Exemplarily, the electrode leads 240 may be formed from at least one of nickel, copper, nickel-plated copper, or aluminum. The electrode leads 240 and the electrode tabs 230 can be electrically connected by various welding methods, including ultrasonic welding, but physical fastening methods such as rivets may also be applied.

[0028] Exemplary, an insulating member 245 may be placed over a region of the electrode lead 240. For example, the insulating member 245 can be made of a material having insulating and adhesive properties (e.g., thermoplastic resin) and can be bonded to a portion of the battery case 50 while covering a portion of the electrode lead 240, thereby ensuring electrical insulation between the electrode lead 240 and the battery case 50. In the region where the electrode lead 240 protrudes from the inside to the outside of the battery case 50, the insulating member 245 can act as a buffer to seal the battery case 50 while simultaneously preventing damage that may occur to the electrode lead 240 during the sealing process of the battery case 50.

[0029] 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 a region sealed to shield the electrode assembly 200 at least a portion of the end of the receiving portion 150.

[0030] On the other hand, the battery case 50 can be formed by joining an upper case 52 and a lower case 54. The upper case 52 and the lower case 54 can be joined to each other, for example, by crimping or heat sealing in the sealing portion 170 region, thereby preventing external foreign matter and moisture from flowing into the electrode assembly 200 located inside the receiving portion 150.

[0031] For example, the battery case 50 may be formed from at least one pouch sheet 110 made of a flexible material (e.g., an aluminum laminate sheet). Such a pouch sheet 110 may be processed to include an inner recess in order to form a receiving portion 150, which is a space for receiving the electrode assembly 200. The recess formed in the pouch sheet 110 may be provided to correspond to the shape and size of the electrode assembly 200.

[0032] On the other hand, Figure 1 shows that only the lower case 54 includes a recessed shape for forming the receiving portion 150, and the upper case 52 does not appear to include a separate recessed structure. However, in the various embodiments of this disclosure, the upper case 52 also includes a recessed shape for forming the receiving portion 150, similar to the lower case 54, and it can of course be understood that a single receiving portion 150 is realized by the combination of the upper case 52 and the lower case 54. For example, the upper case 52 and the lower case 54 can have substantially symmetrical structures and can each be formed by a pouch sheet 110 including a recess 112 as shown in Figures 2a and 2c. Alternatively, as shown in Figure 1, the upper case 52 may not have a recessed shape, and only the lower case 54 may have a recessed shape.

[0033] Figures 3 to 5 illustrate a method for manufacturing a secondary battery 100 according to one embodiment of the present disclosure. Specifically, Figure 3 is a schematic front view of a pouch sheet 110 for forming the case 50 of the secondary battery 100 according to one embodiment of the present disclosure. Figures 4 and 5 are schematic front and side views illustrating the seal area 310 and reseal area 320 in the pouch sheet 110 of the secondary battery 100 according to one embodiment of the present disclosure, respectively.

[0034] Referring to Figures 3 to 5, the battery case 50 of the secondary battery 100 in various embodiments can be manufactured using at least one pouch sheet 110.

[0035] For example, the case 50 of the secondary battery 100 may be formed by arranging an electrode assembly 200 between two pouch sheets 110 and joining the periphery where the electrode assembly 200 is located by sealing or resealing. On the other hand, each of the two pouch sheets 110 may include a recess 112, and the joining of the two pouch sheets 110 can form a receiving portion 150 space in which the electrode assembly 200 is housed in the inner space of the two recesses 112. For example, the two pouch sheets 110 may be substantially symmetrical or have the same structure.

[0036] Although not shown in the illustration, in other examples, the case 50 of the secondary battery 100 may be formed by folding both ends of a single pouch sheet 110 so that they enclose each other, arranging the electrode assembly 200 inside the folded portion, and then joining the open ends so that the electrode assembly 200 is sealed inside.

[0037] On the other hand, in the manufacturing process of the secondary battery 100, after stacking two pouch sheets 110 to form a battery case 50 and receiving the electrode assembly 200 inside, an electrolyte may be injected into the battery case 50 and the ends of the battery case 50 may be sealed.

[0038] In particular, the sealing process may be carried out in the following order: first, the remaining area of ​​the multiple ends forming the end sealing region 310 of the battery case 50 is sealed, excluding one end; then, the electrolyte is injected through the unsealed end; and finally, the unsealed end is also sealed. In this case, the end that is sealed last in the battery case 50, i.e., the end into which the electrolyte is injected, may be the end located relatively far from the end of the pouch sheet 110 where the recess 112 is formed (for example, the right end of the sealing region 310 of the pouch sheet 110 shown in Figure 4).

[0039] Next, once the seal region 310, which is the entire end of the battery case 50, is sealed, the secondary battery 100 may be subjected to formation. Formation is a process in which an SEI layer (Solid Electrolyte Interphase layer) is formed on the surface of the electrodes 220 of the electrode assembly 200 through the charging process, causing it to become charged, thereby allowing the secondary battery 100 to be charged and able to supply power.

[0040] On the other hand, the electrolyte applied to the secondary battery 100 in various embodiments of this disclosure may include a gel polymer electrolyte. Compared to general liquid electrolytes, gel polymer electrolytes have the advantage of being able to maintain a constant battery thickness and, due to the inherent adhesive strength of the gel, can be used to manufacture thin-film batteries with excellent electrical and chemical stability.

[0041] In the case where the electrolyte applied to the secondary battery 100 is a gel polymer electrolyte, a curing step may be further performed to gel the liquid gel polymer electrolyte. In a method for manufacturing a secondary battery according to one embodiment of the present disclosure, the curing step may be performed immediately before formation. However, the manufacturing sequence is not limited to this, and in other embodiments, the curing step for gelation may be performed after formation.

[0042] Next, once the secondary battery 100 has been cured and formed, a portion of the sealed battery case 50 may be cut open for degassing. For example, the cutting of the secondary battery 100 into the case 50 may be performed along the CC line of the pouch sheet 110 shown in Figures 3 and 4.

[0043] Subsequently, after degassing and resealing operations are performed under vacuum conditions, the packaging process of the secondary battery 100 can be completed. At this time, the resealing (i.e., resealing) operation may be performed in the resealing region 320 shown in Figures 4 and 5. The resealing region 320 may include at least a portion of the area that has been opened by the cutting operation performed along the CC line, which is the area around the end of the recess 112 inside the case 50 where the electrode assembly 200 is placed in the secondary battery 100 (i.e., the area corresponding to the seal portion 170 of the battery case 50). For example, as shown in Figure 4, the resealing region 320 may be an area that extends in the x-axis direction and overlaps with the sealing region 310, which has been opened in the direction toward the CC line in the recess 112, and may be an area adjacent to the recess 112 in particular.

[0044] On the other hand, when manufacturing the secondary battery 100 according to the process described above, electrolyte may adhere to the resealable region 320 during the electrolyte injection process, resulting in incomplete sealing in the resealable region 320. This could allow oxygen and moisture to enter the electrode assembly 200 inside the battery case 50, potentially impairing the aesthetic appearance of the secondary battery 100. In particular, when using a gel polymer electrolyte, the electrolyte hardens during the curing process, leaving a jelly-like substance in the resealable region 320. Consequently, proper sealing may not be achieved, potentially leading to a greater problem of cosmetic defects.

[0045] As a result, in the secondary battery 100 according to various embodiments of this disclosure, masking tape is applied in advance to a portion of the pouch sheet 110 forming the battery case 50, and after proceeding with a predetermined process, the battery case 50 is cut open for degassing, the applied masking tape which may have electrolyte on it is removed, and after the removal of the masking tape, degassing and resealing work is performed, thereby preventing the presence of electrolyte in the predetermined area where the masking tape was applied and preventing the occurrence of defects caused by electrolyte as described above.

[0046] Figures 6 and 7 are schematic front and side views of a pouch sheet 110, illustrating a region 330 on which masking tape is applied in the pouch sheet 110 forming the battery case 50 of a secondary battery 100 according to one embodiment of the present disclosure.

[0047] Each of the two opposing pouch sheets 110 that face each other to form the battery case 50 may have masking tape pre-applied to it, corresponding to an area 330 that is at least a portion of the resealable area 320.

[0048] In this case, in order to prevent the problem of the sealing area 310 not being sealed by the masking tape, or the sealing of the sealing area 310 being rendered ineffective by removing the masking tape, masking tape does not need to be applied to the area where the resealable area 320 and the sealing area 310 overlap.

[0049] On the other hand, the area 330 on the pouch sheet 110 to which masking tape is applied in advance may have a larger margin area than the area of ​​the resealable area 320 excluding the sealing area 310.

[0050] For example, the width of the area 330 to which the masking tape is applied can be set to be the same as or larger than the width of the resealable area 320, thereby more reliably preventing electrolytes from adhering to the resealable area 320.

[0051] In one embodiment, the masking tape can be attached to the inner surfaces of two overlapping pouch sheets 110. The masking tape is in the form of a film with an adhesive layer formed on only one side, and the adhesive layer allows the masking tape to be attached to the pouch sheets 110.

[0052] Masking tape can be attached to each of the two pouch sheets 110. Each masking tape attached to the two pouch sheets 110 has non-adhesive film surfaces facing each other, and an electrolyte can be injected between the two film surfaces of each masking tape.

[0053] On the other hand, each masking tape can be removed after housing the electrode assembly 200 in the recess 112 between the two pouch sheets 110, injecting the electrolyte, sealing against the seal area 310, selectively curing the electrolyte, forming it against the secondary battery 100, and performing an incision along the CC line for degassing. Furthermore, after removing the masking tape in this way, degassing and resealing can be performed under vacuum conditions.

[0054] For example, when a gel polymer electrolyte is applied, the electrolyte is already hardened as the curing process is carried out prior to the incision process. Therefore, even if the battery case 50 is incised and the masking tape is removed from the inner surface of each pouch sheet 110, the electrolyte will no longer adhere to the reseal area 320.

[0055] Figure 8a is a schematic front view illustrating a region 330 on a pouch sheet 110 of a secondary battery 100 according to another embodiment of the present disclosure, to which masking tape is applied. Figure 8b is a schematic diagram showing the shape of the masking tape applied to the pouch sheet 110 in Figure 8a.

[0056] Referring to Figures 8a and 8b, in the manufacturing process of the secondary battery 100 according to various embodiments, the masking tape pre-applied to the pouch sheet 110 for forming the battery case 50 may include a reseal portion 432 corresponding to the reseal area 320 and an extension portion 435 formed by extending in one direction from the reseal portion 432.

[0057] The reseal portion 432 can be attached to a first region 332 of the pouch sheet 110 that corresponds to the area of ​​the reseal region 320 in which the seal region 310 has been excluded. The extension portion 435 may have a shape that extends in the Y-axis direction on one (or more) sides of the first region 332, and may be located, for example, in a second region 335 that does not correspond to the reseal region 320.

[0058] By masking the pouch sheet 110 with masking tape that further includes an extension portion 435 formed in the reseal 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 work for degassing.

[0059] The resealable portion 432 and the extension portion 435 of the masking tape may be configured as a single unit, but the adhesive layer of the masking tape may be formed only on the resealable portion 432. For example, the extension portion 435 of the masking tape does not need to have adhesive strength on both sides of the film layer constituting the masking tape. However, the embodiment is not limited to this, and adhesive layers may be formed on both the resealable portion 430 and the extension portion 435.

[0060] On the other hand, in various embodiments of the present disclosure, the number and location of the extensions 435 of the masking tape and the second regions 335 on the pouch sheet 110 in which the extensions 435 are located are not limited to those shown in Figures 8a and 8b. For example, the extensions 435 may be formed as extensions at both ends of the reseal portion 432, or at both ends and the center of the reseal portion 432, and various other modified structures can be applied.

[0061] Figure 9 is an image of the peripheral area of ​​the reseal region 320 of a secondary battery 100 manufactured without masking tape in the comparative manufacturing method, and Figure 10 is an image of the peripheral area of ​​the reseal region 320 of a secondary battery 100 manufactured using masking tape in the manufacturing method according to one embodiment of the present disclosure.

[0062] Referring to Figures 9 and 10, in the comparative configuration of Figure 9, where masking tape is not used, it can be visually confirmed that electrolyte remains on the pouch sheet 110 around the resealable area 320, causing staining. However, in the case of the result according to the embodiment of Figure 10, where masking tape is used, it can be confirmed that no electrolyte remains on the pouch sheet 110 around the resealable area 320, and no appearance defects occur.

[0063] In this specification, terms such as "up" and "down" are used to indicate directions, but these terms are for convenience of explanation and it will be obvious to those skilled in the art that they may change depending on the position of the object in question, the observer's position, etc.

[0064] Although 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 obvious to anyone with average knowledge of the art that various modifications and variations are possible as long as they do not deviate from the technical idea of ​​the present invention as described in the claims. Furthermore, some components of the above-described embodiments may be omitted, and each embodiment may be combined with others.

Claims

1. A method for manufacturing a secondary battery, The first step is to prepare at least one pouch sheet with masking tape attached, The steps include: housing the electrode assembly inside a battery case formed by stacking at least one of the aforementioned pouch sheets; The steps include injecting an electrolyte into the battery case and sealing the end of the battery case, The steps include performing a formation on the aforementioned secondary battery, After cutting open a portion of the battery case, the masking tape is removed and degassed. A method for manufacturing a secondary battery, comprising the step of resealing the area corresponding to the removed masking tape.

2. The area of ​​the pouch sheet to which the masking tape is attached is, The resealing region in which the resealing is performed is at least partially included, A method for manufacturing a secondary battery according to claim 1, wherein the sealing region where the sealing is performed is not included.

3. The aforementioned masking tape is A resealing section corresponding to the resealing area where the resealing is performed, A method for manufacturing a secondary battery according to claim 1, comprising an extension formed in one direction from the reseal portion.

4. The method for manufacturing a secondary battery according to claim 3, wherein the extension portion does not include an adhesive layer.

5. The aforementioned electrolyte includes a gel electrolyte, A method for manufacturing a secondary battery according to claim 1, further comprising the step of performing a curing step to gel the gel electrolyte before performing the formation.

6. The step of sealing the end of the battery case is as follows: The steps include sealing a portion of the open end of the battery case, A method for manufacturing a secondary battery according to claim 1, comprising the steps of injecting an electrolyte into the battery case and then sealing the remaining portion of the open end.

7. A pouch sheet for manufacturing battery cases for secondary batteries, The aforementioned pouch sheet is A recess for receiving the electrode assembly, The recess and a masking tape that is detachably attached to one side adjacent to the recess, The masking tape is a pouch sheet that extends along the length of the area to be resealed so as to correspond at least partially to the area to be resealed during the manufacturing process of the secondary battery.

8. The aforementioned masking tape is A resealing portion corresponding to the area to be resealed, The pouch sheet according to claim 7, further comprising an extension portion formed in a direction other than the longitudinal direction in the reseal portion.

9. The resealable portion includes an adhesive layer. The pouch sheet according to claim 8, wherein the extension portion does not include an adhesive layer.

10. The aforementioned masking tape is The pouch sheet according to claim 7, which is removed during the manufacturing process of a secondary battery, after the incision for degassing and before the degassing operation.

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