Pouch-shaped battery cell with attached vent and method of manufacturing the same

Abstract

A pouch-shaped battery cell and a method for manufacturing the same are disclosed, the pouch-shaped battery cell comprising: a pouch-shaped battery case made of a laminate sheet; an electrode assembly accommodated in the pouch-shaped battery case; and a vent configured to discharge gas in the pouch-shaped battery case, wherein the pouch-shaped battery case is provided with an opening, the opening being opened or closed by the vent attached to the inner side of the opening, wherein the vent opens to quickly discharge gas when pressure in the pouch-shaped battery cell increases, and the vent reversibly blocks the interior and exterior of the battery cell.

Description

Technical Field

[0001] This application claims the benefit of priority to Korean Patent Application No. 2019-0166594, filed on Dec. 13, 2019, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a pouch-shaped battery cell with a vent attached thereto and a method for manufacturing the same, and more particularly, to a pouch-shaped battery cell with a vent attached to the inner surface of a pouch-shaped battery case and a method for manufacturing the same, wherein the vent can be opened and closed so that gas is smoothly discharged when pressure in the pouch-shaped battery cell increases. Background Art

[0003] Lithium secondary batteries, which are reusable and have high energy density, have attracted attention as new energy sources with environmentally friendly characteristics because they can significantly reduce the use of fossil fuels and do not generate byproducts due to the use of energy.

[0004] Based on the type and shape of the housing member, lithium secondary batteries can be divided into pouch-shaped battery cells made of laminated sheets, cylindrical battery cells made of metal cans, or prismatic battery cells made of metal cans. Electrode assemblies are divided into jelly-roll type electrode assemblies, stacked type electrode assemblies, stacked folding type electrode assemblies, or laminated stacked type electrode assemblies based on their shapes.

[0005] Since the pouch-shaped lithium secondary battery can be easily manufactured to have various sizes, is lightweight, and has high energy density, the pouch-shaped lithium secondary battery has been used as a power source for electric vehicles or hybrid electric vehicles requiring high-output and high-capacity energy.

[0006] The pouch-shaped lithium secondary battery is manufactured by accommodating an electrode assembly and an electrolyte in a pouch-shaped battery case made of a laminate sheet and hermetically sealing the periphery of the battery case using heat and pressure.

[0007] In the process of manufacturing lithium secondary batteries, gas is generated due to the decomposition of the electrolyte during activation. In addition, gas is generated in the battery cell even during the process of charging and discharging the battery cell and in an abnormal use environment. As a result, the pressure in the battery cell increases.

[0008] This pressure increase may cause the explosion of the battery cell. For this reason, research has been conducted to discharge gas to the outside before the battery explodes in order to ensure the safety of the battery.

[0009] In this regard, Patent Document 1 relates to a battery module to which a valve member is added, the valve member including a porous membrane made of a Teflon-based resin, wherein the valve member is made of a porous membrane such as PTFE, and the porous membrane is fixed by a supporting member to the lower side of a vent hole formed in a housing cover.

[0010] That is, Patent Document 1 discloses a valve member applied to a battery module case, but does not disclose a vent member that can be applied to a pouch-shaped battery cell.

[0011] Patent Document 2 relates to a secondary battery having a structure configured to discharge gas in a battery case through a passage defined in a protrusion formed integrally with the battery case, wherein the protrusion and the passage protrude from one side of the periphery of the battery case.

[0012] Therefore, there is a high demand for a pouch-shaped battery cell and a method for manufacturing the same having a structure in which gas is smoothly discharged when the pressure in the pouch-shaped battery cell increases without increasing the outer size of the battery case and the battery can continue to be used after the gas is discharged.

[0013] (Prior art literature)

[0014] (Patent Document 1) Korean Patent Application Publication No. 2012-0009592 (2012.02.02)

[0015] (Patent Document 2) Korean Patent Application Publication No. 2018-0038880 (April 17, 2018) Summary of the invention

[0016] Technical issues

[0017] The present invention has been made in view of the above problems, and an object of the present invention is to provide a pouch-shaped battery cell and a method for manufacturing the same, the pouch-shaped battery cell having a vent attached to the inner side of an opening formed in a pouch-shaped battery case, the vent being openable and closable.

[0018] Technical Solution

[0019] In order to achieve the above-mentioned purpose, a pouch-shaped battery cell with a vent attached thereto according to the present invention includes: a pouch-shaped battery case made of a laminate sheet; an electrode assembly accommodated in the pouch-shaped battery case; and a vent configured to discharge gas in the pouch-shaped battery case, wherein the pouch-shaped battery case is provided with an opening, and the opening is opened or closed by the vent attached to the inner side of the opening.

[0020] The vent may be configured to have a structure in which a first layer having pores formed therein and a second layer having no pores formed therein are stacked.

[0021] The first layer and the second layer may be made of the same material.

[0022] The material may be polytetrafluoroethylene (PTFE).

[0023] The pouch-shaped battery case may include an outer resin layer, a metal layer, and an inner resin layer, and the vent may be attached such that the first layer and the inner resin layer contact each other.

[0024] The inner resin layer may be hardened in a state where a portion of the inner resin layer is melted and moved into the pores of the first layer, so that the inner resin layer and the first layer may be bonded to each other.

[0025] The vent portion may be attached to a portion of the pouch-shaped battery case adjacent to the sealing portion.

[0026] The pouch-shaped battery case may include: a first battery case in which an electrode assembly accommodating portion is formed, and a second battery case coupled to the first battery case, the second battery case being configured to hermetically seal the pouch-shaped battery case together with the first battery case, and the vent may be attached to at least one of a central portion of the first battery case and a central portion of the second battery case.

[0027] In addition, the present invention provides a method for manufacturing a pouch-shaped battery cell. Specifically, the method for manufacturing a pouch-shaped battery cell includes: (a) preparing a laminate sheet having an opening formed therein; (b) attaching a vent portion to the opening; (c) shaping the laminate sheet to manufacture a pouch-shaped battery case; and (d) accommodating an electrode assembly in the pouch-shaped battery case and hermetically sealing the pouch-shaped battery case.

[0028] The vent may be configured to have a structure in which a first layer having pores formed therein and a second layer having no pores formed therein are stacked.

[0029] The first layer and the second layer may be made of the same material.

[0030] The material may be polytetrafluoroethylene (PTFE).

[0031] Furthermore, the present invention provides a battery pack including the pouch-shaped battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a perspective view of a pouch-shaped battery cell in which a vent according to a first embodiment is formed.

[0033] Figure 2 is a perspective view of a pouch-shaped battery cell in which a vent according to a second embodiment is formed.

[0034] Figure 3 It is along Figure 1 A partial enlarged view of the vertical section taken along line A-A'.

[0035] Figure 4 This is a SEM photograph of the first layer of the ventilation part.

[0036] Figure 5 This is a SEM photograph of the second layer of the ventilation portion.

[0037] Figure 6 yes Figure 3 Another embodiment of .

[0038] Figure 7 This is a SEM photograph of the overlapping joint portion between the pouch-shaped battery case and the vent. DETAILED DESCRIPTION

[0039] Now, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the preferred embodiments of the present invention. However, in describing the working principle of the preferred embodiments of the present invention in detail, when the detailed description of the known functions and structures incorporated herein may obscure the subject matter of the present invention, the detailed description will be omitted.

[0040] In addition, the same reference numerals will be used throughout the drawings to represent components that perform similar functions or operations. Where a component is referred to as being connected to another component throughout the application, the component may not only be directly connected to the other component, but the component may also be indirectly connected to the other component via another component. In addition, the inclusion of a certain element does not mean the exclusion of other elements, but means that other elements may be further included unless otherwise specified.

[0041] Unless otherwise specifically limited, the description that embodies elements by limitation or addition is applicable to all inventions and does not limit the specific invention.

[0042] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0043] Figure 1 is a perspective view of a pouch-shaped battery cell in which a vent according to the first embodiment is formed.

[0044] Reference Figure 1 , the pouch-shaped battery cell 100 is configured to have a structure in which an electrode assembly is accommodated together with an electrolyte in a pouch-shaped battery case made of a laminate sheet and the outer circumference of the pouch-shaped battery case is sealed.

[0045] The electrode assembly may be a one-way electrode assembly in which the positive electrode lead 101 and the negative electrode lead 102 protrude in one direction. Figure 1 Different from that shown in FIG. 1 , the electrode assembly may be a bidirectional electrode assembly in which the positive electrode lead and the negative electrode lead protrude in different directions.

[0046] The pouch-shaped battery case 110 includes: a first battery case 111 in which an electrode assembly receiving portion 113 is formed; and a second battery case 112 coupled to the first battery case 111 to hermetically seal the pouch-shaped battery case 110. An opening is formed at a central portion of the second battery case 112, and a vent 130 is attached to an inner side of the opening.

[0047] The vent 130 has a circular planar shape. Since the size of the vent is larger than the diameter of the opening formed in the pouch-shaped battery case 110, the vent blocks the opening of the pouch-shaped battery case from the inside of the pouch-shaped battery case.

[0048] Although in Figure 1 Although not shown, a vent may be formed in the central portion of the first battery case 111 in addition to the central portion of the second battery case 112. Alternatively, a vent may be formed only in the central portion of the first battery case.

[0049] In the case where the pouch-shaped battery case 110 expands due to the gas generated in the pouch-shaped battery cell 100 due to the side reaction of the pouch-shaped battery cell 100, the central portions of the first and second battery cases expand the most, so that pressure may be concentrated in the central portions of the first and second battery cases. In this case, the difference between the pressure of the gas at the vent and the pressure outside the pouch-shaped battery cell increases, so the gas may be discharged through the pores of the vent.

[0050] That is, in the case where there is no or almost no difference between the pressure in the pouch-shaped battery cell and the pressure outside the pouch-shaped battery cell, no gas is discharged through the vent according to the present invention, and the vent prevents foreign matter from entering the battery cell. However, in the case where the pressure difference between the inside and outside of the pouch-shaped battery cell is 0.1atm or more, the gas in the pouch-shaped battery cell is discharged through the first layer and the second layer of the vent due to the pressure difference. In the case where the pressure difference between the inside and outside of the pouch-shaped battery cell is less than 0.1atm due to the gas being discharged to a certain extent, or there is no pressure difference between them, the process of blocking gas discharge can be reversibly performed.

[0051] Figure 2 is a perspective view of a pouch-shaped battery cell in which a vent according to a second embodiment is formed.

[0052] Reference Figure 2, except that the position of the vent 230 is formed in Figure 1 The pouch-shaped battery cell 200 is structurally similar to the pouch-shaped battery cell 100 except that the position of the vent 130 in the pouch-shaped battery cell 100 is different. Figure 1 The same as the pouch-shaped battery cell.

[0053] Figure 2 The vent portions 230 are configured to have a structure in which three vent portions 230 are attached to a portion of the pouch-shaped battery case adjacent to the sealing portion 215 in a state of being spaced apart from each other.

[0054] Figure 2 The radius of the vent 230 shown in FIG. Figure 1 The radius of the vent 130 is shown to be small. The number, size, and location of the vents may be selectively applied, taking into account the attachment location of the vent, the size of the battery housing, and the amount of gas generated.

[0055] Figure 3 It is along Figure 1 FIG. 2 is a partial enlarged view of a vertical section taken along the line AA′ of FIG. 1 , which shows in detail the structure of a pouch-shaped battery case to which the vent according to the present invention is attached.

[0056] Reference Figure 3 , the pouch-shaped battery case 110 includes an outer resin layer 110 a , a metal layer 110 b , and an inner resin layer 110 c .

[0057] The outer resin layer 110a is used to protect the battery cell from external influences. Therefore, the outer resin layer is required to exhibit excellent tolerance to the external environment, and therefore the outer resin layer is required to have excellent tensile strength and weather resistance for its thickness. For example, polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or polyethylene naphthalate (PEN); polyolefin resins such as polyethylene (PE) or polypropylene (PP); polystyrene resins such as polystyrene; polyvinyl chloride resins; or polyvinylidene chloride resins. These materials may be used alone or as a mixture of two or more materials, and an oriented nylon (ONy) film may be further used.

[0058] The metal layer may be made of aluminum (Al) or an aluminum alloy so as to exhibit a function of improving the strength of the battery case in addition to the function of preventing foreign matter such as gas and moisture from entering or electrolyte leakage. Examples of aluminum alloys may include alloy numbers 8079, 1N30, 8021, 3003, 3004, 3005, 3104, and 3105. These materials may be used alone or as a mixture of two or more materials.

[0059] A polymer resin that exhibits thermal fusibility (thermal bonding), has low hygroscopicity to the electrolyte to suppress the penetration of the electrolyte, and is not swollen or corroded by the electrolyte can be used as the inner resin layer. Preferably, polypropylene, acid-modified polypropylene, or a combination thereof is used.

[0060] In a preferred example, the pouch-shaped battery case according to the present invention may be configured to have a structure in which the thickness of the outer resin layer is 5 μm to 40 μm, the thickness of the metal layer is 20 μm to 150 μm, and the thickness of the inner resin layer is 10 μm to 50 μm. In the case where the thickness of each layer of the laminate is too small, it is difficult to achieve the material barrier function and the strength improvement, which is undesirable. On the other hand, in the case where the thickness of each layer of the laminate is too large, the formability is reduced, and the thickness of the sheet is increased, which is also undesirable.

[0061] The vent 130 according to the present invention is configured to have a structure in which a first layer 131 having pores formed therein and a second layer 132 having no pores formed therein are stacked. The first layer 131 and the second layer 132 are made of the same material, such as polytetrafluoroethylene (PTFE).

[0062] PTFE exhibits excellent electrolyte tolerance, heat resistance, and hydrophobicity. Therefore, PTFE can be used as a material for the vent attached to the inside of the pouch-shaped battery case.

[0063] The first layer 131 of the vent 130 and the second layer 132 of the vent are different in shape in that pores are formed in the first layer, but no pores are formed in the second layer.

[0064] In connection with this, Figure 4 This is a SEM photo of the first layer of the ventilation part. Figure 5 This is a SEM photograph of the second layer of the ventilation portion.

[0065] Reference Figure 4 and Figure 5 , it can be seen that Figure 4 The first layer has a structure in which open pores are formed so that the inside and the outside of the first layer communicate with each other, Figure 5The second layer of has a structure in which the surface of the second layer is rough but no pores are formed. However, since the second layer is made of PTFE, the gas can be discharged through the micro gaps in the polymer.

[0066] That is, the inner resin layer of the pouch-shaped battery case can be melted into the pores of the first layer of the vent so that the vent can be stably attached to the inner surface of the pouch-shaped battery case. Gas generated in the pouch-shaped battery case can be discharged to the outside through the first and second layers of the vent.

[0067] In addition, the melting point of PTFE is 327° C., which is greatly different from the melting point of about 160° C. of polypropylene (PP) mainly used as an inner resin layer of a pouch-shaped battery case.

[0068] In the case where heat and pressure are applied to attach a vent made of PTFE to an inner resin layer made of PP, if heat is applied to the extent that the PTFE melts, the PP is damaged. On the other hand, in the case where heat is applied to the extent that the PP melts but does not damage the PP, since the PTFE is not melted, it is difficult to bond the vent and the inner resin layer to each other.

[0069] In the present invention, a structure is used in which the vent is attached to the pouch-shaped battery case so that the first layer 131 formed with pores is in contact with the inner resin layer 110c of the pouch-shaped battery case. Therefore, in the case where a high temperature and high pressure are applied to the overlapping portion between the pouch-shaped battery case and the vent so as to attach the vent to the pouch-shaped battery case, the inner resin layer 110c is hardened in a state where a portion of the inner resin layer is melted and moved into the pores of the first layer 131, so that the first layer 131 and the inner resin layer 110c are combined with each other in a state where the inner resin layer is anchored to the first layer 131.

[0070] Figure 6 yes Figure 3 Another embodiment of the present invention shows in detail the structure of a pouch-shaped battery case to which a vent according to the present invention is attached.

[0071] Reference Figure 6 , the pouch-shaped battery case 310 is configured to have a structure in which an outer resin layer 310a, an adhesive layer 310d, a metal layer 310b, an adhesive layer 310d, and an inner resin layer 310c are sequentially stacked in a downward direction in the figure, Figure 3 The difference between the pouch-shaped battery case shown in is that an adhesive layer is further provided between the outer resin layer and the metal layer, and an adhesive layer is further provided between the metal layer and the inner resin layer. That is, by providing an adhesive layer, Figure 6 The adhesion between the layers of the pouch-shaped battery case can be greater than Figure 3The adhesion between the layers of the pouch-shaped battery case.

[0072] The vent 330 includes a first layer 331 in which pores are formed and a second layer 332 in which pores are not formed, and the first layer 331 is attached to the inner resin layer 310 c .

[0073] Therefore, when heat and pressure are applied to the overlapping portion between the vent and the pouch-shaped battery case 310 so as to attach the vent to the pouch-shaped battery case, the inner resin layer 310c melts and moves to the pores of the first layer 331, so that the inner resin layer and the first layer are bonded to each other by anchoring.

[0074] In addition, even in the case where the vent is attached to the outside of the opening of the pouch-shaped battery case, when the pressure in the pouch-shaped battery case increases due to the gas, a gas discharge effect can be achieved. However, in this case, the metal layer of the pouch-shaped battery case is exposed from the portion of the pouch-shaped battery case where the opening is formed. As a result, hydrofluoric acid generated due to the side reaction of the electrolyte corrodes the metal layer made of aluminum, which is undesirable.

[0075] Figure 7 This is a SEM photograph of the overlapping joint portion between the pouch-shaped battery case and the vent.

[0076] Reference Figure 7 The pouch-shaped battery case includes an outer resin layer 410a, a metal layer 410b, and an inner resin layer 410c. The vent 430 has a structure in which a first layer 431 and a second layer 432 are stacked.

[0077] The outer resin layer 410a has a structure in which a PET layer, an adhesive layer, a nylon layer, and an adhesive layer are sequentially stacked in an inward direction. The metal layer 410b is a layer made of aluminum. The inner resin layer 410c may be made of a combination of polypropylene and acid-modified polypropylene, or may be made of a cast polypropylene film.

[0078] The vent 430 includes a first layer 431 made of PTFE and having pores formed therein, and a second layer 432 made of PTFE and having no pores formed therein.

[0079] Before the pouch-shaped battery case and the vent are coupled to each other, the total thickness of the outer resin layer may be 33.1 μm, the thickness of the metal layer may be 41.4 μm, and the thickness of the inner resin layer may be 80 μm.

[0080] The inner resin layer may be manufactured by extruding each of polypropylene and acid-modified polypropylene on the metal layer, and the inner resin layer may be laminated with the metal layer and the outer resin layer to manufacture a pouch-shaped battery case. The thickness of the polypropylene may be 40 μm, and the thickness of the acid-modified polypropylene may be 40 μm.

[0081] Alternatively, the inner resin layer may be made of a cast polypropylene (CPP) film having a thickness of 80 μm. The cast polypropylene film may be attached to the metal layer using an adhesive, and the cast polypropylene film and the metal layer may be laminated with the outer resin layer to manufacture a pouch-shaped battery case.

[0082] When heat and pressure are applied to the pouch-shaped battery case and the vent so that the pouch-shaped battery case and the vent are bonded to each other, the polypropylene of the inner resin layer melts and moves into the pores of the first layer. Figure 7 As shown in , the thickness of the inner resin layer is reduced to 12.2 μm, and no voids are seen in the first layer 431 .

[0083] That is, it can be seen that the inner resin layer enters the pores of the first layer, and the inner resin layer and the first layer are bonded to each other by anchoring, thereby uniformly achieving overall adhesion between the inner resin layer and the first layer. Therefore, the vent is stably attached to the inner side of the pouch-shaped battery case.

[0084] The temperature required to attach the first layer and the inner resin layer to each other may be 180° C. to 220° C., the pressure required to attach the first layer and the inner resin layer to each other may be 0.05 MPa to 0.5 MPa, and the application time may be selectively applied within the range of 1 second to 5 seconds.

[0085] As a specific example, when gas is generated in a pouch-shaped battery cell due to a side reaction of the electrolyte, the pressure in the pouch-shaped battery cell becomes greater than the external atmospheric pressure, so that the gas can be discharged through the opening formed in the pouch-shaped battery case and the first and second layers of the vent.

[0086] Therefore, in the pouch-shaped battery cell according to the present invention, the process of discharging the gas in the battery cell through the vent when the pressure in the battery cell increases, and blocking the gas discharge and preventing external moisture from entering when the pressure in the battery cell becomes equal to the external atmospheric pressure can be reversibly performed.

[0087] In addition, the method for manufacturing a pouch-shaped battery cell according to the present invention may include: (a) preparing a laminate sheet having an opening formed therein; (b) attaching a vent to the opening; (c) forming the laminate sheet to manufacture a pouch-shaped battery case; and (d) housing an electrode assembly in the pouch-shaped battery case and hermetically sealing the pouch-shaped battery case.

[0088] That is, in consideration of processing convenience, it is preferable that the opening is formed before the electrode assembly receiving portion is formed, and the electrode assembly receiving portion is formed in a state where the vent is attached to the opening.

[0089] However, as necessary, step (b) may be performed between step (c) and step (d). Alternatively, the steps of forming an opening in the laminate sheet and attaching the vent to the opening may be performed between step (c) and step (d).

[0090] The vent may be configured to have a structure in which a first layer having pores formed therein and a second layer having no pores formed therein are stacked, and each of the first layer and the second layer may be made of PTFE.

[0091] Those skilled in the art to which the present invention pertains will appreciate that various applications and modifications are possible within the scope of the present invention based on the above description.

[0092] (Explanation of reference numbers)

[0093] 100, 200: Pouch cell

[0094] 101: Positive lead

[0095] 102: Negative lead

[0096] 110, 310: Pouch-shaped battery case

[0097] 110a, 310a, 410a: External resin layer

[0098] 110b, 310b, 410b: Metal layer

[0099] 110c, 310c, 410c: inner resin layer

[0100] 111: First battery housing

[0101] 112: Second battery housing

[0102] 113: Electrode assembly receiving portion

[0103] 130, 230, 330, 430: Ventilation

[0104] 131, 331, 431: First floor

[0105] 132, 332, 432: Second layer

[0106] 215: Sealing part

[0107] 310d: Adhesive layer.

[0108] Industrial Applicability

[0109] As apparent from the above description, the pouch-shaped battery cell according to the present invention is configured to have a structure in which a vent is attached to the inside of a battery case, and thus an increase in size of the battery cell due to the addition of the vent can be minimized.

[0110] Furthermore, when the pressure in the battery cell increases, the gas is immediately discharged, and thus the pressure in the battery cell can be maintained at a predetermined level.

[0111] Furthermore, the vent according to the present invention is not broken when opened but can be opened and closed to be used reversibly, so that the battery cell can be continuously used after the gas is exhausted.

Claims

1. A pouch-shaped battery cell, comprising: A pouch-shaped battery case made of a laminate sheet, wherein the pouch-shaped battery case comprises an outer resin layer, a metal layer, and an inner resin layer; an electrode assembly accommodated in the pouch-shaped battery case; as well as a vent configured to discharge gas in the pouch-shaped battery case, the vent having a structure in which a first layer having pores formed therein and a second layer having no pores formed therein are stacked, the first layer and the second layer being made of the same material, polytetrafluoroethylene, and the pores in the first layer being open pores through which the inside and the outside of the first layer communicate with each other, wherein the pouch-shaped battery case is provided with an opening, the opening being opened or closed by the vent attached to the inner side of the opening, wherein the vent is attached so that the first layer and the inner resin layer are in contact with each other, wherein the inner resin layer is hardened in a state where a portion of the inner resin layer is melted and moved into the pores of the first layer, so that the inner resin layer and the first layer are bonded to each other by anchoring, and Here, in a state where the inner resin layer and the vent are overlapped and bonded, a thickness of the inner resin layer is thinner than a thickness of the inner resin layer before bonding. 2 . The pouch-shaped battery cell according to claim 1 , wherein the vent portion is attached to a portion of the pouch-shaped battery case adjacent to a sealing portion.

3. The pouch-shaped battery cell according to claim 1, wherein The pouch-shaped battery housing comprises: a first battery case in which an electrode assembly accommodating portion is formed, and a second battery case coupled to the first battery case, the second battery case being configured to hermetically seal the pouch-shaped battery case together with the first battery case, and The vent is attached to at least one of a central portion of the first battery case and a central portion of the second battery case.

4. A method for manufacturing a pouch-shaped battery cell, the method comprising: (a) preparing a laminated sheet having an opening formed therein; (b) attaching a vent portion to the opening, the vent portion having a structure in which a first layer having pores formed therein and a second layer having no pores formed therein are stacked, the first layer and the second layer being made of the same material, polytetrafluoroethylene, and the pores in the first layer being open pores through which the inside and the outside of the first layer communicate with each other; (c) forming the laminated sheet to produce a pouch-shaped battery case; as well as (d) accommodating an electrode assembly in the pouch-shaped battery case and hermetically sealing the pouch-shaped battery case, The pouch-shaped battery case includes an outer resin layer, a metal layer and an inner resin layer. wherein the vent is attached so that the first layer and the inner resin layer are in contact with each other, wherein the inner resin layer is hardened in a state where a portion of the inner resin layer is melted and moved into the pores of the first layer, so that the inner resin layer and the first layer are bonded to each other by anchoring, and Here, in a state where the inner resin layer and the vent are overlapped and bonded, a thickness of the inner resin layer is thinner than a thickness of the inner resin layer before bonding. 5 . A battery pack comprising the pouch-shaped battery cell according to claim 1 .

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