Multilayer films in pouch form, fabrication methods for these multilayer films in pouch form, and pouch-type secondary batteries.

Abstract

The invention relates to a multilayer pouch-like film comprising a stretch support layer, a gas barrier layer, and a sealing layer, laminated sequentially, wherein the stretch support layer comprises a first stretch nylon film and a second stretch nylon film laminated sequentially, and this multilayer pouch-like film has a TSTM value expressed by equation 1 in the range of 0.80 to 1.24. Equation 1: TSTM = (TST) / (TSM). In equation 1, TST is the tensile strength in the TD direction (N / 15 mm) of the multilayer pouch-like film, and TSM is the tensile strength in the MD direction (N / 15 mm) of the multilayer pouch-like film.

Description

Pouch film laminate, method for manufacturing the same, and pouch-type secondary battery Cross-citation with related applications This application claims the benefit of priority to Korean Patent Application No. 10-2023-0157720, dated November 14, 2023, the entire contents of which are incorporated herein by reference. Technical field The present invention relates to a pouch film laminate, a method for manufacturing the same, and a pouch-type secondary battery. Typically, secondary batteries are manufactured by applying electrode active material slurry to a positive electrode current collector and a negative electrode current collector to manufacture a positive electrode and a negative electrode, laminating them on both sides of a separator to form an electrode assembly of a predetermined shape, then housing the electrode assembly in a battery case, injecting electrolyte, and sealing it. Secondary batteries are classified into pouch type and can type depending on the material of the case that accommodates the electrode assembly. The pouch type accommodates the electrode assembly in a pouch made of a flexible polymer material. The can type accommodates the electrode assembly in a case made of a material such as metal or plastic. A pouch-type battery case is manufactured by performing press processing on a flexible pouch film laminate to form a cup portion. Then, when the cup portion is formed, an electrode assembly is accommodated in the receiving space of the cup portion and the sealing portion is sealed to manufacture a secondary battery. Among these press processes, drawing forming is performed by inserting a pouch film into a press device and applying pressure to the pouch film laminate with a punch to stretch the pouch film laminate. The pouch film laminate is generally formed of multiple layers in which a polymer film such as polyethylene terephthalate is laminated on one side of a gas barrier layer made of a metal material, and a sealant layer is laminated on the other side. Recently, as the demand for high-capacity batteries such as electric vehicle batteries and ESS batteries increases, the demand for battery cases that can accommodate more electrode assemblies is increasing. Accordingly, a two-cup molding method is being attempted in which the depth of the cup molding of a pouch-type battery case is increased, or the cup volume is increased by molding the cups in the upper case and the lower case, respectively. In the conventional manufacture of pouch film laminates, the substrate layer and / or the metal barrier layer were manufactured thickly in order to increase the cup portion volume. However, there are problems in that the cup portion forming depth is not sufficiently increased, or the thickness of the pouch film laminate is thickened, which reduces the energy density, reduces the ease of moisture drying, and reduces the insulation. Therefore, there is a need for the development of a pouch film laminate having excellent insulation properties and ease of moisture drying without causing cracks even when the cup forming depth is increased. The present invention is intended to solve the above problems, and provides a pouch film laminate, a pouch-type battery case, and a pouch-type secondary battery having excellent formability, insulation, and ease of moisture drying by controlling the ratio of tensile strengths in the MD direction and the TD direction of a pouch film laminate to a certain level or less while using a double layer of stretched nylon films. The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned can be clearly understood by those skilled in the art from the description below. [1] The present invention is a pouch film laminate comprising a sequentially laminated stretching auxiliary layer, a gas barrier layer, and a sealant layer, wherein the stretching auxiliary layer comprises a sequentially laminated first stretching nylon film layer and a second stretching nylon film layer, and the pouch film laminate comprises a TS represented by the following formula 1. TM A pouch film laminate having a value of 0.80 to 1.24 is provided. [Formula 1] TS TM= (TS T ) / (TS M ) In the above formula 1, TS T is the tensile strength (N / 15mm) in the TD direction of the above pouch film laminate, and TS M is the MD direction tensile strength (N / 15mm) of the above pouch film laminate. [2] In the present invention, in the above [1], the thickness of the extension auxiliary layer can be 10 ㎛ to 80 ㎛. [3] In the present invention, in the above [1] or [2], the thickness of the first stretched nylon film layer can be 5 ㎛ to 40 ㎛. [4] In at least one of the above [1] to [3], the thickness of the second stretched nylon film layer can be 5 µm to 40 µm. [5] In at least one of the above [1] to [4], the first stretched nylon film layer and the second stretched nylon film layer may be made of the same material. [6] The present invention is characterized in that in at least one of the above [1] to [5], the pouch film laminate is T represented by the following formula 2. N This can be more than 1.5. [Formula 2] T N = (T N,A ) / (T N,B ) In the above equation 2, T N,A is the property of the above extension auxiliary layer, and T N,B is the toughness of the stretching auxiliary layer made of a single-layer stretched nylon film with a thickness of 15㎛. [7] The present invention may further include a surface protective layer formed on the extension auxiliary layer in at least one of the above [1] to [6]. [8] In at least one of the above [1] to [7], the thickness of the gas barrier layer may be 20 ㎛ to 150 ㎛. [9] In at least one of the above [1] to [8], the thickness of the sealant layer may be 30 ㎛ to 130 ㎛.

[0010] The present invention provides a method for manufacturing a pouch film laminate, comprising: a step of sequentially laminating a first stretched nylon film layer and a second stretched nylon film layer to manufacture a stretching auxiliary layer; and a step of sequentially laminating the stretching auxiliary layer, a gas barrier layer, and a sealant layer to manufacture a pouch film laminate; wherein the first stretched nylon film layer and the second stretched nylon film layer are arranged with stretching directions alternating with each other.

[0011] In the present invention, in the above

[0010] , the first stretched nylon film layer and the second stretched nylon film layer may be arranged so that their respective stretching directions intersect at an angle of 75° to 90°.

[0012] The present invention provides a pouch-type secondary battery including a pouch-type battery case manufactured by drawing-molding at least one of the pouch film laminates among [1] to [9] above. The pouch film laminate according to the present invention has a higher breakdown voltage when a pinhole occurs and is easy to dry due to moisture than a pouch film laminate using a conventional stretched nylon film having a single-layer structure, thereby realizing excellent insulation and processability. The pouch film laminate according to the present invention can realize better formability by reducing the imbalance in tensile properties such as tensile strength and toughness according to the direction of the pouch film laminate by controlling the stretching direction and the lamination direction of the stretched nylon film when laminating a double layer of stretched nylon films. The drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the contents of the invention described above, serve to better understand the technical idea of ​​the present invention, so the present invention is not limited to the matters described in such drawings. Meanwhile, the shape, size, scale or ratio of elements in the drawings included in this specification may be exaggerated to emphasize a clearer explanation. Figure 1 is a cross-sectional view of a pouch film laminate according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of a pouch film laminate according to one embodiment of the present invention. Figure 3 is an exploded assembly diagram of a secondary battery according to one embodiment of the present invention. Figure 4 is a conventional sequential lamination method of auxiliary extension layers. FIG. 5 is a drawing showing a sequential lamination method of an extension auxiliary layer according to one embodiment of the present invention. Figure 6 is an example of a stress-strain curve for measuring toughness according to Experimental Example 2 of the present invention. Hereinafter, the present invention will be described more preferably. The terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as having 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 or her own invention in the best manner. In the present invention, the MD direction (Machine Direction) means the longitudinal direction of the pouch film laminate, and the TD direction (Transverse Direction) means the width direction of the pouch film laminate. The inventors of the present invention have found that a pouch-type secondary battery having excellent formability, insulation, and ease of moisture drying can be implemented by using a double layer of a stretched nylon film as an extension auxiliary layer and controlling the ratio of the tensile strength in the MD direction and the TD direction according to the stretching direction of the stretched nylon film during each thickness and lamination, thereby completing the present invention. The pouch film laminate according to the present invention, the method for manufacturing the same, and the pouch-type secondary battery include at least one of the following disclosed configurations, and may include any combination between technically possible configurations among the following configurations. Pouch film laminate FIG. 1 illustrates one embodiment of a pouch film laminate according to the present invention. Hereinafter, the pouch film laminate according to the present invention will be described with reference to FIG. 1. Referring to FIG. 1, a pouch film laminate (1) according to the present invention is a pouch film laminate (1) including a sequentially laminated stretching auxiliary layer (13), a gas barrier layer (20), and a sealant layer (30), and the stretching auxiliary layer (13) includes a sequentially laminated first stretching nylon film layer (14) and a second stretching nylon film layer (15). The above pouch film laminate (1) is represented by the following formula 1: TS TM The values ​​are between 0.80 and 1.24. [Formula 1] TS TM = (TS T ) / (TS M ) In the above formula 1, TS T is the tensile strength (N / 15mm) in the TD direction of the above pouch film laminate, and TS M is the MD direction tensile strength (N / 15mm) of the above pouch film laminate. In the conventional manufacture of pouch film laminates, the thickness of the base layer (stretching protection layer and surface protection layer) and / or the metal barrier layer is manufactured thick in order to increase the cup portion volume. However, even if the thickness is manufactured thick, the cup portion forming depth is not sufficiently increased, or the thickness of the pouch film laminate is thickened, so that the energy density decreases, the ease of moisture drying is reduced, and the insulation is reduced. In particular, when a nylon film thicker than the conventionally commercially available 15 ㎛ or 25 ㎛ thick nylon film is used as the stretching protection layer, additional process costs may be consumed, and the problem of difficulty in moisture drying may occur due to the thickened thickness. In addition, in the case of the stretched nylon film, it has mechanical properties suitable for pouch film laminate molding compared to the non-stretched nylon film, but the stretched nylon film has directionality due to its characteristics. In this case, there is a change in the mechanical properties such as tensile strength and elongation between the stretching direction and the vertical direction, and since pouch molding is performed by stretching in all directions, if the tensile properties differ depending on the direction, there may be a problem of reduced formability due to the imbalance of the properties. For example, if each stretched nylon film is stretched in the MD direction as shown in Fig. 4, and a stretching auxiliary layer is manufactured by arranging a double-layer stretched nylon film so that the stretching directions are located on the same line, compared to the stretching auxiliary layer including a single-layer stretched nylon film, since it is configured as a double layer, when a pinhole occurs in one layer of the stretched nylon film, the dielectric breakdown voltage is high and moisture drying can be easy. However, since the double-layer stretched nylon films are arranged so that the stretching direction is on the same line, there may be a problem of reduced formability due to an imbalance in tensile properties such as tensile strength and toughness depending on the direction. Therefore, the pouch film laminate according to the present invention, for example, as shown in FIG. 5, comprises a stretching auxiliary layer by forming a double layer of stretched nylon films, and includes double layers of stretched nylon films with opposite stretching directions within the pouch film laminate to solve the above problem. Specifically, each of the stretched nylon films included in the double-layer stretched nylon film is included in the pouch film laminate so as to have different stretching directions. That is, since the pouch film laminate having the double-layer stretched nylon film layers is manufactured to be isotropic, the insulation breakdown voltage is high when a pinhole occurs due to the double-layer configuration, and not only is moisture drying easy, but also the pouch film laminate is manufactured to be isotropic, so that excellent formability can be implemented. According to one embodiment of the present invention, the pouch film laminate (1) is represented by the following formula 1: TS TM The value may be from 0.80 to 1.24, preferably from 0.85 or more, from 0.90 or more or from 0.95 or more, and may be from 1.20 or less, from 1.15 or less, from 1.10 or less or from 1.05 or less, and preferably from 0.95 to 1.05. [Formula 1] TS TM = (TS T ) / (TS M ) In the above formula 1, TS T is the tensile strength (N / 15mm) in the TD direction of the above pouch film laminate, and TS M is the MD direction tensile strength (N / 15mm) of the above pouch film laminate. TS above TMWhen the value is less than 0.80 or more than 1.24, the tensile properties of the stretched nylon film in the pouch film laminate differ greatly depending on the direction, so that a problem occurs in which the formability of the pouch film laminate deteriorates when the cup part is formed. In addition, even if the cup part is formed, the tensile properties in one direction are deteriorated, so there is a problem in which cracks are likely to occur when an external force is applied in the direction in which the tensile properties are deteriorated. Therefore, when the above range is satisfied, the tensile properties of the pouch film laminate are similar depending on the direction, so that excellent formability is realized, while preventing the occurrence of cracks due to external force. According to one embodiment of the present invention, the TS T The tensile strength may be 150 N / 15 mm to 320 N / 15 mm, preferably 160 N / 15 mm or more, 170 N / 15 mm or more, 180 N / 15 mm or more, or 189 N / 15 mm or more, and may be 320 N / 15 mm or less, 300 N / 15 mm or less, 280 N / 15 mm or less, or 265 N / 15 mm or less, and more preferably 189 N / 15 mm to 265 N / 15 mm. When the above range is satisfied, it may be preferable in that excellent toughness of the pouch film laminate can be implemented while also implementing an excellent forming depth. According to one embodiment of the present invention, the TS M The tensile strength may be 150 N / 15 mm to 320 N / 15 mm, preferably 160 N / 15 mm or more, 170 N / 15 mm or more, 180 N / 15 mm or more, or 182 N / 15 mm or more, and may be 320 N / 15 mm or less, 300 N / 15 mm or less, 280 N / 15 mm or less, or 260 N / 15 mm or less, and more preferably 182 N / 15 mm to 260 N / 15 mm. When the above range is satisfied, it may be preferable in that an excellent forming depth can be achieved while implementing excellent toughness of the pouch film laminate. Below, each component is described in more detail. (Extension auxiliary layer) The above-mentioned stretching auxiliary layer (13) is arranged on the outer layer of the battery case to assist stretching of the pouch film laminate (1) so that it is not easily broken when stretching of the pouch film laminate (1) occurs during the forming process of the pouch film laminate (1). According to one embodiment of the present invention, the thickness of the stretching auxiliary layer (13) may be 10 ㎛ to 80 ㎛, preferably 20 ㎛ to 70 ㎛, more preferably 35 ㎛ to 65 ㎛, and even more preferably 40 ㎛ to 60 ㎛. When the above range is satisfied, excellent formability of the pouch film laminate can be secured, while preventing a decrease in the energy density per volume of the secondary battery due to the thickness of the pouch film laminate becoming excessively thick. The above-mentioned stretching auxiliary layer (13) includes a first stretching nylon film layer (14) and a second stretching nylon film layer (15) that are sequentially laminated. According to one embodiment of the present invention, the thickness of the first stretched nylon film layer (14) may be 5 µm to 40 µm, preferably 10 µm to 30 µm, more preferably 10 µm to 25 µm, and even more preferably 15 µm to 20 µm. When the above range is satisfied, excellent formability of the pouch film laminate can be secured, while preventing a decrease in the energy density per volume of the secondary battery due to the thickness of the pouch film laminate becoming excessively thick. In addition, it is also preferable in terms of facilitating moisture drying. According to one embodiment of the present invention, the thickness of the second stretched nylon film layer (15) may be 5 ㎛ to 40 ㎛, preferably 15 ㎛ to 40 ㎛, more preferably 20 ㎛ to 35 ㎛, and even more preferably 20 ㎛ to 30 ㎛. When the above range is satisfied, excellent formability of the pouch film laminate can be secured, while preventing a decrease in the energy density per volume of the secondary battery due to the thickness of the pouch film laminate becoming excessively thick. In addition, it is also preferable in terms of facilitating moisture drying. According to one embodiment of the present invention, the first stretched nylon film layer (14) and the second stretched nylon film layer (15) may each independently include a stretched nylon film obtained by stretching a nylon film, which is a polyamide-based film. Specifically, the first stretched nylon film layer and the second stretched nylon film layer may each independently be a stretched nylon film layer obtained by stretching a nylon film layer including at least one selected from the group consisting of nylon 6,6, nylon MXD6 (polyxylylene adipamide), nylon 4, nylon 4,6, and nylon 4,10. When the above conditions are satisfied, each of the stretched nylon film layers can have excellent tensile strength and elongation, and is preferable in that it can have excellent chemical resistance. According to one embodiment of the present invention, the first stretched nylon film layer (14) and the second stretched nylon film layer (15) may be the same material, or may be different materials, but preferably, the first stretched nylon film layer (14) and the second stretched nylon film layer (15) may be the same material. When the above condition is satisfied, it may be preferable in terms of maximizing the physical properties or characteristics of a specific stretched nylon film layer. For example, when nylon 6,6 is used as the first stretched nylon film layer (14), nylon 6,6 may also be used as the second stretched nylon film layer (15). According to one embodiment of the present invention, the first stretched nylon film layer (14) and the second stretched nylon film layer (15) may each independently include a uniaxially stretched nylon film. According to one embodiment of the present invention, the first stretched nylon film layer (14) may include a uniaxially stretched nylon film. Here, stretching refers to a method of imparting orientation to a specific material by pulling it in the MD direction or the TD direction between the softening temperature and the melting temperature and then cooling it. Therefore, a nylon film stretched in one direction is called a uniaxially stretched nylon film, and a uniaxially stretched nylon film that is stretched once more in a direction perpendicular to the uniaxial direction is called a biaxially stretched (biaxially stretched) nylon. When the first stretched nylon film layer (14) includes a uniaxially stretched nylon film, it is possible to realize better flexibility and elasticity than when it includes a biaxially stretched film, and it is possible to realize excellent processability and cost-saving effects. According to one embodiment of the present invention, the second stretched nylon film layer (15) may include a uniaxially stretched nylon film. Here, stretching refers to a method of imparting orientation to a specific material by pulling it in the MD direction or the TD direction between the softening temperature and the melting temperature and then cooling it. Therefore, a nylon film stretched in one direction is called a uniaxially stretched nylon film, and a nylon film that is stretched once more in a direction perpendicular to the uniaxial direction is called a biaxially stretched (biaxially stretched) nylon. When the first stretched nylon film layer (15) includes a uniaxially stretched nylon film, it is possible to realize better flexibility and elasticity than when it includes a biaxially stretched film, and it is possible to realize excellent processability and cost-saving effects. According to one embodiment of the present invention, the stretching auxiliary layer (13) may take 12 hours or less, preferably 10 hours or less, and more preferably 8 hours or less, to dry in a dry room at 25° C., until the moisture content becomes 1000 ppm or less. When the above range is satisfied, the time and energy required for manufacturing a pouch film laminate may be reduced, thereby realizing excellent processability. According to one embodiment of the present invention, the pouch film laminate (1) is T represented by the following formula 2 N This can be greater than or equal to 1.5, preferably greater than or equal to 2.0, and more preferably greater than or equal to 2.5. [Formula 2] T N = (T N,A ) / (T N,B ) In the above equation 2, T N,A is the property of the above extension auxiliary layer, and T N,B is the toughness of the stretching auxiliary layer made of a single-layer stretched nylon film with a thickness of 15㎛. The toughness of the above-mentioned extension auxiliary layer can be measured through a stress-strain curve, a graph showing the relationship between stress and strain. Specifically, when a tensile force is applied to a material, the relationship between stress and strain can be represented graphically. At this time, if the vertical axis of the graph is stress and the horizontal axis is strain, the area under the graph is the toughness of the material. Toughness refers to the degree of material resistance to destruction, and the higher the toughness, the more the material can be stretched before it is destroyed. At this time, the vertical axis stress is the stress divided by the cross-sectional area perpendicular to the load direction when applying a load to the material (ρ = W / A, W: kgf, A: mm 2 ), and the strain on the horizontal axis is the ratio of the deformation to the size of the original object (ε = (l 1 -l 0 ) / (l 0 ), l 0 : Length before load, l 1 : It means the length after applying a load. In addition, the toughness according to the present invention means the area under the graph when the strain is at the breaking point. According to one embodiment of the present invention, the pouch film laminate may have an outer layer insulation breakdown voltage of 500 V or higher, preferably 530 V or higher, and more preferably 560 V or higher when a pinhole occurs in the stretching auxiliary layer. Specifically, the outer layer insulation breakdown voltage may be 500 V or higher, preferably 530 V or higher, and more preferably 560 V or higher when a pinhole occurs in the first stretching nylon film layer. When the above range is satisfied, the external insulation required for a battery module or pack can be provided, and this is preferable in that sufficient external insulation can be provided even if a pinhole occurs in either the first or second stretching auxiliary layer. According to one embodiment of the present invention, the stretching protection layer (13) may include metal oxide particles. The metal oxide particles may remove moisture within the stretching protection layer (13) by being hydroxylated by reaction with moisture introduced into the stretching protection layer (13). The metal oxide particles may include at least one selected from the group consisting of CaO, MnO, SrO, MgO, and ZnO. Preferably, the metal oxide particles may include at least one of CaO and MgO, which are advantageous for hydroxylation with moisture. According to one embodiment of the present invention, the stretching protection layer (13) may further include an additive. By including an additive in the stretching protection layer (13), the physical properties of the stretching protection layer (13) may be changed. For example, as an additive for controlling the tensile strength of the stretching protection layer (13), at least one of carbon fiber, glass fiber, and aramid fiber may be added. (Surface protection layer) FIG. 2 illustrates one embodiment of a pouch film laminate according to the present invention. Hereinafter, the pouch film laminate according to the present invention will be described with reference to FIG. 2. According to one embodiment of the present invention, the pouch film laminate (1) may include a surface protection layer (12) on the outermost surface of the pouch film laminate, and more specifically, may include a surface protection layer (12) formed on the stretching auxiliary layer (13). The surface protection layer (12) may play a role in protecting the battery from external impact, and since it comes into direct contact with hardware, it is required to have insulation and heat resistance. According to one embodiment of the present invention, the material of the surface protection layer (12) may include a single layer or two or more composite layers selected from polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), low-density polyethylene (LDPE), and high-density polyethylene (HDPE), and preferably may be formed of polyethylene terephthalate. The above polyethylene terephthalate (PET) has excellent durability and electrical insulation properties, and thus, when the PET film is placed on the surface side, it exhibits excellent durability and insulation properties. However, in the case of the PET film, the adhesion to the aluminum alloy thin film constituting the gas barrier layer (20) is weak, and the stretching behavior is also different, so when the PET film is placed on the gas barrier layer side, the substrate layer and the gas barrier layer may be peeled off during the forming process, and the gas barrier layer may not be stretched uniformly, which may cause a problem in that the formability is reduced. In contrast, since the stretching auxiliary layer (13) has a similar stretching behavior to the aluminum alloy thin film constituting the gas barrier layer (20), when the stretching auxiliary layer (13) is placed between the polyethylene terephthalate and the gas barrier layer, an effect of improving the formability can be obtained. According to one embodiment of the present invention, the thickness of the surface protection layer (12) may be 5 ㎛ to 30 ㎛, preferably 5 ㎛ to 20 ㎛, more preferably 5 ㎛ to 15 ㎛, and even more preferably 7 ㎛ to 15 ㎛. When the above range is satisfied, the surface protection effect, formability, and post-molding rigidity are excellent. (Gas barrier layer) The gas barrier layer (20) is laminated between the extension auxiliary layer (13) and the sealant layer (30) to secure the mechanical strength of the pouch, block the ingress of gas or moisture from outside the secondary battery, and prevent electrolyte leakage from inside the pouch-type battery case. According to one embodiment of the present invention, the gas barrier layer (20) may be formed of a metal. For example, the gas barrier layer may be a metal thin film including at least one metal selected from the group consisting of aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti), and invar (INVAR), but is not limited thereto. According to one embodiment of the present invention, the gas barrier layer (20) may be formed of an aluminum alloy thin film. When the gas barrier layer (20) is formed using an aluminum alloy thin film, a mechanical strength higher than a predetermined level can be secured, while being light in weight and securing electrochemical properties and heat dissipation properties by the electrode assembly and the electrolyte. The aluminum alloy thin film may contain elements other than aluminum (Al). For example, the aluminum alloy thin film may contain at least one selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn). According to an embodiment of the present invention, the gas barrier layer (20) may be formed of a stainless steel thin film. Preferably, the gas barrier layer (20) may be manufactured by forming and / or processing a stainless steel thin film. The gas barrier layer (20) formed of stainless steel has a relatively low thermal conductivity, which is effective in preventing or delaying heat diffusion to other cells during thermal runaway, and has a relatively high toughness, which can suppress crack generation in the pouch during use of the pouch-type battery. The stainless steel may include at least one selected from the group consisting of elements other than iron (Fe), for example, copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn). According to an embodiment of the present invention, the thickness of the gas barrier layer (20) may be 20 μm to 150 μm, preferably 30 μm to 140 μm, more preferably 40 μm to 100 μm, and even more preferably 60 μm to 80 μm. When the above range is satisfied, the formability of the gas barrier layer is improved, so that when the pouch film laminate is drawn and formed, the depth of the cup portion can be formed deeper, the outer wall of the cup portion can be closer to vertical, and the radius of curvature of the cup portion corner can also be reduced. Accordingly, since the volume of the accommodating portion increases, more electrode assemblies can be stacked on the electrode assembly accommodated therein, and the energy efficiency per unit volume can increase. Also, without significantly increasing the manufacturing cost, without reducing the thickness of the sealant layer, the overall thickness of the pouch may not increase significantly, and the sealing durability may not decrease. (Sealant layer) The sealant layer (30) is for completely sealing the inside of the pouch-type battery case when the pouch-type battery case accommodating the electrode assembly therein is sealed, and the sealant layers are thermally adhered to each other at the sealing portion. For this purpose, the sealant layer (30) may be formed of a material having excellent thermal adhesion strength. According to one embodiment of the present invention, the sealant layer (30) may be formed of a material having insulating, corrosion-resistant, and sealing properties. Preferably, since the sealant layer (30) is in direct contact with the electrode assembly and / or the electrolyte inside the pouch-shaped battery case, it may be formed of a material having insulating and corrosion-resistant properties. In addition, since the sealant layer (30) must completely seal the inside of the pouch-shaped battery case to block material movement between the inside and the outside, it may be formed of a material having high sealing properties (e.g., excellent thermal bonding strength). In order to secure such insulating, corrosion-resistant, and sealing properties, the sealant layer (30) may be formed of a polymer material. According to one embodiment of the present invention, the sealant layer (30) may be made of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, and Teflon, and preferably may be made of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may be composed of cast polypropylene (CPP), acid modified polypropylene (Acid Modified Polypropylene, PPa), a polypropylene-ethylene copolymer, and / or a polypropylene-butylene-ethylene terpolymer. According to one embodiment of the present invention, the thickness of the sealant layer (30) may be 30 ㎛ to 130 ㎛, preferably 40 ㎛ to 120 ㎛, and more preferably 60 ㎛ to 100 ㎛. When the thickness of the sealant layer satisfies the above range, there is an effect of securing the sealing strength of the sealing portion while also securing the formability of the pouch film laminate. According to one embodiment of the present invention, the sealant layer (30) according to the present invention may have a composite film structure in which two or more materials are each formed to form layers. For example, the sealant layer (30) may have a multilayer structure. An adhesive layer and / or a skin layer may be arranged between each layer of the sealant layer (30) having the composite film structure. The adhesive layer and / or the skin layer may have thermal adhesiveness and thus may play a role in assisting adhesion between each layer of the sealant layer (30). For example, the adhesive layer and / or the skin layer may include a polypropylene-based resin, but is not limited thereto. In addition, the adhesive layer and / or the skin layer may be arranged between the sealant layer (30) and the gas barrier layer (20). The pouch film laminate (1) of the present invention as described above can be manufactured through a method for manufacturing a pouch film laminate known in the art. For example, the pouch film laminate of the present invention can be manufactured through a method of attaching a stretching auxiliary layer (13) to an upper surface of a gas barrier layer (20) through an adhesive, and forming a sealant layer (30) on a lower surface of the gas barrier layer (20) through coextrusion or an adhesive layer, and can be manufactured through a method such as dry lamination or sandwich lamination. However, the method for manufacturing the pouch film laminate is not limited thereto. According to one embodiment of the present invention, the pouch film laminate (1) may have a total thickness of 120 µm to 300 µm, preferably 140 µm to 280 µm, and more preferably 160 µm to 260 µm. When the thickness of the pouch film laminate satisfies the above range, the forming depth can be increased while minimizing a decrease in the battery accommodation space and a decrease in sealing durability due to an increase in the thickness of the pouch laminate. According to one embodiment of the present invention, when the pouch film laminate (1) is formed to have one cup portion measuring 160 mm in width x 90 mm in length after cutting the pouch film laminate to a size of 240 mm x 266 mm, the forming depth at which a crack occurs may be 10 mm or more, preferably, the forming depth at which a crack occurs may be 12 mm or more, more preferably, the forming depth at which a crack occurs may be 14 mm or more, and even more preferably, the forming depth at which a crack occurs may be 16 mm or more. When the above range is satisfied, the cup portion forming depth becomes deeper, so that more electrode assemblies can be accommodated, which is preferable in that the energy density per volume of the battery can be increased. Method for manufacturing a pouch film laminate Next, a method for manufacturing a pouch film laminate according to the present invention will be described. A method for manufacturing a pouch film laminate according to the present invention comprises: (1) a step of sequentially laminating a first stretched nylon film layer and a second stretched nylon film layer to manufacture a stretching auxiliary layer; and (2) a step of sequentially laminating the stretching auxiliary layer, a gas barrier layer, and a sealant layer to manufacture a pouch film laminate; wherein the first stretched nylon film layer and the second stretched nylon film layer are arranged such that stretching directions are alternately arranged. First, the step of manufacturing a stretching auxiliary layer by sequentially laminating a first stretching nylon film layer and a second stretching nylon film layer is described. The specific composition, physical properties, etc. of the first stretched nylon film layer and the second stretched nylon film layer have been described above and are therefore omitted. According to one embodiment of the present invention, the first stretched nylon film layer and the second stretched nylon film layer are arranged so that their stretching directions are alternately arranged. Since the stretched nylon film has a directionality according to its nature according to stretching, changes occur in the mechanical properties such as tensile strength and elongation between the stretching direction and the perpendicular direction. At this time, since the pouch forming is performed while stretching in all directions, if a difference in the tensile properties occurs depending on the direction, there may be a problem of reduced formability due to the imbalance of the properties. That is, if a pouch film laminate is manufactured by arranging double-layer stretched nylon films, each stretched in the MD direction as in FIG. 4, so that their respective stretching directions are positioned on the same line, a problem of reduced formability may occur. Therefore, the pouch film laminate according to the present invention aims to solve the above problem by manufacturing the pouch film laminate by disposing the stretching directions of the double-layer stretched nylon films, each stretched in the MD direction, in different directions, as shown in FIG. 5. Specifically, since the double layers of stretched nylon films are included in the pouch film laminate with different orientations from each other, and the pouch film laminate can be manufactured to be isotropic, even when the pouch film laminate is manufactured by drawing and forming a pouch-shaped battery case, the difference in the physical properties of the pouch film laminate between the TD direction and the MD direction is not excessive, and thus excellent formability can be realized. In addition, since the stretching auxiliary layer includes a double-layer stretching nylon film, the insulation breakdown voltage is high when a pinhole occurs, and moisture drying is easy. According to an embodiment of the present invention, the first drawn nylon film layer and the second drawn nylon film layer are arranged such that their drawing directions are offset from each other. Preferably, the first drawn nylon film layer and the second drawn nylon film layer may be arranged such that their respective drawing directions intersect at an angle of 75° to 90°, more preferably 80° to 90°, and even more preferably 90°. When the above range is satisfied, the pouch film laminate can be manufactured to be isotropic, so that the difference in drawing physical properties according to the drawing direction of the pouch film laminate is not excessive, and excellent moldability can be achieved. The drawing direction can be measured as the angle with the straight line of the drawing direction of the second drawn nylon film layer when the drawing direction of the first drawn nylon film layer is assumed to be a straight line on the x-axis. Preferably, it can be measured as the smaller angle among the angles generated when the straight line of the drawing direction of the first drawn nylon film layer and the straight line of the drawing direction of the second drawn nylon film layer are translated and crossed. Next, the step of manufacturing a pouch film laminate by sequentially laminating the drawing assist layer, the gas barrier layer, and the sealant layer will be described. Regarding the composition, physical properties, etc. of the drawing assist layer, the gas barrier layer, and the sealant layer, they are omitted as described above. The drawing assist layer, the gas barrier layer, and the sealant layer can be sequentially laminated to produce a pouch film laminate. As disclosed in FIG. 1, among the drawing assist layers, the first drawn nylon film layer (14) is located on the outer surface of the pouch film laminate (1), and the second drawn nylon film layer (15) is located on the inner surface, specifically, on the gas barrier layer surface. At this time, the method for manufacturing a pouch film laminate according to the present invention may, in some cases, include a step of sequentially laminating the surface protection layer (12), the stretching auxiliary layer (13), the gas barrier layer (20), and the sealant layer (30) described above, as disclosed in FIG. 2. Preferably, a pouch film laminate can be manufactured by sequentially laminating the gas barrier layer (20) by attaching a stretching auxiliary layer (13) to the upper surface of the gas barrier layer (20) using an adhesive, attaching a surface protection layer (12) to the upper surface of the stretching auxiliary layer (13) using an adhesive, and forming a sealant layer (30) on the lower surface of the gas barrier layer (20) using coextrusion or an adhesive layer, and by using a method such as dry lamination or sandwich lamination. However, the method for manufacturing the pouch film laminate is not limited thereto. Pouch-type secondary battery Next, a pouch-type secondary battery according to the present invention will be described. Figure 3 is an exploded assembly drawing of a pouch-type secondary battery (200) according to the present invention. As illustrated in FIG. 3, a pouch-type secondary battery (200) according to the present invention may include a pouch-type battery case (210) manufactured by molding the aforementioned pouch film laminate, and an electrode assembly (260) housed in the pouch-type battery case (210). Preferably, the pouch-type secondary battery (200) of the present invention may include a pouch-type battery case (210), an electrode assembly (260), an electrode lead (280), an insulator (290), and an electrolyte (not shown). Hereinafter, each component of the pouch-type secondary battery of the present invention will be described in more detail with reference to FIG. 3. (Pouch-type battery case) The pouch-shaped battery case (210) can be manufactured by molding the pouch film laminate of the present invention described above, and preferably, can be manufactured by drawing molding the pouch film laminate of the present invention. The pouch-shaped battery case (210) can store an electrode assembly (260) inside. Since the detailed configuration and physical properties of the pouch film laminate are the same as those described above, a detailed description is omitted. The pouch film laminate may be drawn and stretched by a punch or the like to manufacture a pouch-shaped battery case (210). As a result, the pouch-shaped battery case (210) may include a cup portion (222) and a receiving portion (224). The receiving portion (224) is a place for receiving an electrode assembly, and may mean a receiving space formed in a pocket shape on the inside of the cup portion (222) as the cup portion (222) is formed. According to one embodiment of the present invention, the pouch-type battery case (210) may include a first case (220) and a second case (230) as illustrated in FIG. 3. The first case (220) includes a receiving portion (224) capable of receiving an electrode assembly (260), and the second case (230) may cover the receiving portion (224) from above to prevent the electrode assembly (260) from being separated from the outside of the battery case (210). The first case (220) and the second case (230) may be manufactured such that one side thereof is connected to each other as illustrated in FIG. 3, but are not limited thereto and may be manufactured in various ways, such as being manufactured separately from each other. According to another embodiment of the present invention, when forming a cup portion in a pouch film laminate, two symmetrical cup portions (222, 232) can be drawn and formed adjacent to each other in one pouch film laminate. In this case, cup portions (222, 232) can be formed in each of the first case (220) and the second case (230) as illustrated in FIG. 3. After the electrode assembly (260) is accommodated in the receiving portion (224) provided in the cup portion (222) of the first case (220), the bridge portion (240) formed between the two cup portions (222, 232) can be folded so that the two cup portions (222, 232) face each other. In this case, the cup portion (232) of the second case (230) can accommodate the electrode assembly (260) from above. Accordingly, since two cup parts (222, 232) accommodate one electrode assembly (260), an electrode assembly (260) having a thicker thickness can be accommodated than when there is only one cup part (222). In addition, since one corner of the secondary battery (200) is formed by folding the pouch-type battery case (210), the number of corners to be sealed can be reduced when performing a sealing process later. Accordingly, the process speed of the pouch-type secondary battery (200) can be improved, and the number of sealing processes can be reduced. The pouch-type battery case (210) may be sealed while housing the electrode assembly (260) so that a portion of the electrode lead (280) described later, i.e., a terminal portion, is exposed. Preferably, when the electrode lead (280) is connected to the electrode tab (270) of the electrode assembly (260) and an insulating portion (290) is formed on a portion of the electrode lead (280), the electrode assembly (260) may be housed in a receiving portion (224) provided in a cup portion (222) of the first case (220), and the second case (230) may cover the receiving portion (224) from above. Subsequently, an electrolyte may be injected into the receiving portion (224), and the sealing portion (250) formed on the edges of the first case (220) and the second case (230) may be sealed. The sealing portion (250) can perform a function of sealing the receiving portion (224). Preferably, the sealing portion (250) can seal the receiving portion (224) while being formed along the edge of the receiving portion (224). The temperature for sealing the sealing portion (250) can be 180° C. to 250° C., preferably 200° C. to 250° C., and more preferably 210° C. to 240° C. When the sealing temperature satisfies the above numerical range, the pouch-type battery case (210) can secure sufficient sealing strength by heat bonding. (electrode assembly) The electrode assembly (260) can be inserted into a pouch-shaped battery case (210) and sealed by the pouch-shaped battery case (210) after electrolyte injection. The electrode assembly (260) may be formed by sequentially stacking an anode, a separator, and a cathode. Preferably, the electrode assembly (260) may include two types of electrodes, an anode and a cathode, and a separator interposed between the electrodes to mutually insulate the electrodes. The positive and negative electrodes may each have a structure in which an active material slurry is applied to an electrode current collector in the form of a metal foil or metal mesh containing aluminum and copper, respectively. The slurry may be formed by stirring a granular active material, an auxiliary conductor, a binder, and a conductive agent while a solvent is added. The solvent may be removed in a subsequent process. A slurry containing an electrode active material and a binder and / or a conductive material is applied to a positive electrode current collector and a negative electrode current collector to manufacture a positive electrode and a negative electrode, and the positive electrode and negative electrode are laminated on both sides of a separator, thereby manufacturing an electrode assembly (260) in a predetermined shape. The types of the electrode assembly (260) may include, but are not limited to, a stack type, a jelly roll type, a stack and folding type, etc. The electrode assembly (260) may include an electrode tab (270). The electrode tabs (270) are respectively connected to the positive and negative electrodes of the electrode assembly (260), and may protrude outwardly from the electrode assembly (260) to serve as a path through which electrons may move between the inside and the outside of the electrode assembly (260). The electrode current collector included in the electrode assembly (260) may be composed of a portion where an electrode active material is applied and a terminal portion where the electrode active material is not applied, i.e., a non-coated portion. The electrode tabs (270) may be formed by cutting the non-coated portion or by connecting a separate conductive member to the non-coated portion by ultrasonic welding, etc. As illustrated in FIG. 2, the electrode tabs (270) may protrude in different directions from each other in the electrode assembly (260), but are not limited thereto, and may be formed to protrude in various directions, such as protruding side by side in the same direction from one side. (electrode leads) The electrode lead (280) can supply electricity to the outside of the secondary battery (200). The electrode lead (280) can be connected to the electrode tab (270) of the electrode assembly (260) by spot welding, etc. The electrode lead (280) is connected to the electrode assembly (260) and may protrude to the outside of the pouch-type battery case (210) via the sealing portion (250). Preferably, one end of the electrode lead (280) is connected to the electrode assembly (260), particularly to the electrode tab (270), and the other end of the electrode lead (280) may protrude to the outside of the pouch-type battery case (210). The electrode lead (280) may include a positive lead (282) having one end connected to the positive tab (272) and extending in the protruding direction of the positive tab (272), and a negative lead (284) having one end connected to the negative tab (274) and extending in the protruding direction of the negative tab (274). Both the positive lead (282) and the negative lead (284) may have other ends protruding outward from the battery case (210). Accordingly, electricity generated inside the electrode assembly (260) may be supplied to the outside. In addition, since the positive tab (272) and the negative tab (274) are formed to protrude in various directions, the positive lead (282) and the negative lead (284) may also extend in various directions, respectively. The positive lead (282) and the negative lead (284) may be made of different materials. That is, the positive electrode lead (282) may be made of the same aluminum (Al) material as the positive electrode collector, and the negative electrode lead (284) may be made of the same copper (Cu) material as the negative electrode collector or a copper material coated with nickel (Ni). A portion of the electrode lead (280) protruding outside the battery case (210) may be a terminal portion and may be electrically connected to an external terminal. (insulating part) The insulating portion (290) prevents electricity generated from the electrode assembly (260) from flowing to the battery case (210) through the electrode lead (280) and can maintain the sealing of the battery case (210). To this end, the insulating portion (290) can be formed of a non-conductive material that does not conduct electricity well. In general, the insulating portion (290) is often made of an insulating tape or film that is easy to attach to the electrode lead (280) and has a relatively thin thickness, but is not limited thereto, and any material capable of insulating the electrode lead (280) can be used. The insulating portion (290) may be arranged to surround the outer surface of the electrode lead (280). Preferably, at least a portion of the electrode lead (280) may be surrounded by the insulating portion (290). In this case, the insulating portion (290) may be arranged between the electrode lead (280) and the pouch-type battery case (210). The insulating portion (290) may be positioned limited to the sealing portion (250) where the first case (220) and the second case (230) of the pouch-type battery case (210) are heat-sealed, and may adhere the electrode lead (280) to the battery case (210). (electrolyte) The pouch-type secondary battery (200) according to the present invention may further include an electrolyte (not shown) that is poured inside the pouch-type battery case (210). The electrolyte is for moving lithium ions generated by an electrochemical reaction of an electrode during charging / discharging of the secondary battery (200), and may include a non-aqueous organic electrolyte that is a mixture of a lithium salt and an organic solvent, or a polymer using a polymer electrolyte. Furthermore, the electrolyte may include a solid electrolyte of a sulfide type, an oxide type, or a polymer type, and such a solid electrolyte may have flexibility that is easily deformed by an external force. Hereinafter, the present invention will be described in more detail through specific examples. However, the following examples are only examples to help understand the present invention and do not limit the scope of the present invention. It will be obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present description, and it is natural that such changes and modifications fall within the scope of the appended patent claims. Examples and Comparative Examples Example 1: Preparation of pouch film laminate A stretching auxiliary layer was manufactured by sequentially laminating a first stretched nylon film (uniaxially stretched nylon film) having a thickness of 15 ㎛, an adhesive layer having a thickness of 3 ㎛, and a second stretched nylon film (uniaxially stretched nylon film) having a thickness of 25 ㎛. At this time, the first stretched nylon film and the second stretched nylon film were laminated so that their stretching directions intersected each other by 90°. Thereafter, a 3-㎛ thick adhesive layer, the above-mentioned fabricated stretching auxiliary layer, a 3-㎛ thick adhesive layer, and a 12-㎛ thick polyethylene terephthalate (PET) film as a surface protection layer were sequentially laminated on one side of an 80-㎛ thick aluminum alloy thin film, and an 80-㎛ thick polypropylene (PP) film was sequentially laminated as a sealant layer on the other side of the aluminum alloy thin film. As a result, a pouch film laminate having a structure in which a polypropylene layer / aluminum alloy thin film / adhesive layer / second stretched nylon film / adhesive layer / first stretched nylon film / adhesive layer / polyethylene terephthalate layer are sequentially laminated was manufactured. Example 2: Preparation of pouch film laminate A pouch film laminate was manufactured in the same manner as in Example 1, except that a 60 ㎛ thick aluminum alloy film was used. Example 3: Preparation of pouch film laminate A pouch film laminate was manufactured in the same manner as in Example 1, except that an aluminum alloy film having a thickness of 40 μm was used. Comparative Example 1: Manufacturing of pouch film laminate A pouch film laminate was manufactured in the same manner as in Example 1, except that the first stretched nylon film and the second stretched nylon film were laminated so that their stretching directions did not intersect at 90° to each other but were parallel to each other. Comparative Example 2: Manufacturing of Pouch Film Laminate A pouch film laminate was manufactured in the same manner as in Example 1, except that the first stretched nylon film and the second stretched nylon film were laminated so that their stretching directions did not intersect at 90° to each other but were parallel to each other, and an aluminum alloy thin film having a thickness of 60 μm was used. Comparative Example 3: Manufacturing of pouch film laminate A pouch film laminate was manufactured in the same manner as in Example 1, except that the first stretched nylon film and the second stretched nylon film were laminated so that their stretching directions did not intersect at 90° to each other but were parallel to each other, and an aluminum alloy thin film having a thickness of 40 μm was used. Comparative Example 4: Manufacturing of Pouch Film Laminate A 25 ㎛ thick stretched nylon film (uniaxially stretched nylon film) was manufactured as a stretching auxiliary layer. Thereafter, a 3-㎛ thick adhesive layer, the above-mentioned fabricated stretching auxiliary layer, a 3-㎛ thick adhesive layer, and a 12-㎛ thick polyethylene terephthalate (PET) film as a surface protection layer were sequentially laminated on one side of an 80-㎛ thick aluminum alloy thin film, and an 80-㎛ thick polypropylene (PP) film was sequentially laminated as a sealant layer on the other side of the aluminum alloy thin film. As a result, a pouch film laminate having a structure in which a polypropylene layer / aluminum alloy thin film / adhesive layer / stretched nylon film / adhesive layer / polyethylene terephthalate layer are sequentially laminated was manufactured. Comparative Example 5: Manufacturing of Pouch Film Laminate A 25 ㎛ thick stretched nylon film (uniaxially stretched nylon film) was manufactured as a stretching auxiliary layer. Thereafter, a 3-㎛ thick adhesive layer, the above-mentioned fabricated stretching auxiliary layer, a 3-㎛ thick adhesive layer, and a 12-㎛ thick polyethylene terephthalate (PET) film as a surface protection layer were sequentially laminated on one side of a 60-㎛ thick aluminum alloy film, and an 80-㎛ thick polypropylene (PP) film was sequentially laminated as a sealant layer on the other side of the aluminum alloy film. As a result, a pouch film laminate having a structure in which a polypropylene layer / aluminum alloy thin film / adhesive layer / stretched nylon film / adhesive layer / polyethylene terephthalate layer are sequentially laminated was manufactured. Comparative Example 6: Manufacturing of pouch film laminate A 15 ㎛ thick stretched nylon film (uniaxially stretched nylon film) was manufactured as a stretching auxiliary layer. Thereafter, a 3-㎛ thick adhesive layer, the above-mentioned fabricated stretching auxiliary layer, a 3-㎛ thick adhesive layer, and a 12-㎛ thick polyethylene terephthalate (PET) film as a surface protection layer were sequentially laminated on one side of a 40-㎛ thick aluminum alloy film, and an 80-㎛ thick polypropylene (PP) film was sequentially laminated as a sealant layer on the other side of the aluminum alloy film. As a result, a pouch film laminate having a structure in which a polypropylene layer / aluminum alloy thin film / adhesive layer / stretched nylon film / adhesive layer / polyethylene terephthalate layer are sequentially laminated was manufactured. The above manufacturing method is summarized and shown in [Table 1] below. Surface protection layerExtension auxiliary layerGas barrier layerSealant layerMaterialThickness(㎛)First and second oriented nylon filmExtension direction intersection degree(°)First oriented nylon film thickness(㎛)Second oriented nylon film thickness(㎛)Thickness(㎛)Thickness(㎛)Example 1PET129015258080Example 2PET129015256080Example 3PET129015254080Comparative Example 1PET12015258080Comparative Example 2PET12015256080Comparative Example 3PET12015254080Comparative Example 4PET12-25-8080Comparative Example 5PET12-25-6080Comparative Example 6PET12-15-4080 Experimental Example 1: Measurement of MD and TD direction tensile strength of pouch film laminate The tensile strength in the MD direction and the TD direction of each pouch film laminate manufactured according to Examples 1 to 3 and Comparative Examples 1 to 6 was measured. Specifically, each of the pouch film laminates manufactured according to Examples 1 to 3 and Comparative Examples 1 to 6 was cut to a length (MD direction) × width (TD direction) of 120 mm × 15 mm to manufacture a sample. At this time, the sample was cut so that the length direction of the sample matched the MD direction of the pouch film laminate. Thereafter, the samples were fixed to the UTM device with a grip gap of 50 mm, and the strength at which the samples were pulled at a tensile speed of 5 mm / min was measured as the tensile strength (N / 15 mm). In addition, each of the pouch film laminates manufactured according to Examples 1 to 3 and Comparative Examples 1 to 6 was cut to a length (MD direction) × width (TD direction) of 15 mm × 120 mm to manufacture a sample. At this time, the sample was cut so that the length direction of the sample was identical to the TD direction of the pouch film laminate. Thereafter, the samples were fixed to the UTM device with a grip gap of 50 mm, and the strength at which the samples were pulled at a tensile speed of 5 mm / min was measured as the tensile strength (N / 15 mm). The measured tensile strengths in the MD and TD directions are shown in [Table 2] to [Table 4] below. Experimental Example 2: Measurement of drying time and toughness of the extension auxiliary layer The elongation auxiliary layers manufactured according to Examples 1 to 3 and Comparative Examples 1 to 6 were each dried in a dry room at 25°C, and the time required for the moisture content to become 1000 ppm or less was measured. Specifically, the stretching auxiliary layers manufactured according to Examples 1 to 3 and Comparative Examples 1 to 6 were dried in a dry room at 25°C, and the moisture content of each was measured every 2, 4, 6, 8, 16, and 24 hours. At this time, the time for the moisture content to become 1000 ppm or less was measured as the moisture drying time. The measured results are shown in [Table 2] to [Table 4] below. In addition, the toughness of the extension auxiliary layers manufactured according to Examples 1 to 3 and Comparative Examples 1 to 6 was measured by integrating the area under the SS curve graph when the strain is at the breaking point. Based on the toughness of a 15 ㎛ thick stretched nylon film (Comparative Example 6) as a single layer, the relative values ​​of the toughness in each of the Examples and Comparative Examples are shown in [Tables 2] to [Tables 4] below. Experimental Example 3: Evaluation of pouch film laminate formability and measurement of breakdown voltage (V) when pinholes exist in the stretching auxiliary layer The formability of each pouch film laminate manufactured according to Examples 1 to 3 and Comparative Examples 1 to 6 was evaluated, and the outer layer insulation breakdown voltage (V) was measured when a pinhole existed in the stretching auxiliary layer. Specifically, as a method for evaluating the formability of a pouch film laminate, the pouch film laminates were cut to the same size such that the length (MD direction) x width (TD direction) was 240 mm x 266 mm, and then the forming depth was changed in a battery case forming device having one forming section having the length (MD direction) x width (TD direction) of 160 mm x 90 mm, and the forming depth when a crack occurred was recorded. Here, the punch and the forming section of the battery case forming device were filleted at the corners and edges, and the corner of the punch had a curvature of 2 mm and the corner had a curvature of 0.5 mm, and the corner of the forming section had a curvature of 2.5 mm and the corner had a curvature of 1.5 mm. In addition, the clearance between the punch and the forming section was 0.5 mm. In addition, as a method for measuring the outer layer breakdown voltage (V) when a pinhole exists in the stretching auxiliary layer, a pinhole with a diameter of 0.5 mm was formed in the first stretching nylon film layer by a laser, and then the pouch film laminates were cut to the same size so that the length (MD direction) x width (TD direction) was 100 mm x 266 mm. Thereafter, the gas barrier layer (aluminum layer) and the surface protection layer (polyethylene terephthalate layer) were electrically connected, and then the voltage was increased at a rate of 100 V / s with AC, and when the current value was 0.5 mA or higher, it was considered that the insulation was broken, and the applied voltage value at that time was measured as the outer layer breakdown voltage (V). The measured forming depth (mm) and outer layer insulation breakdown voltage (V) are listed in [Table 2] to [Table 4] below. At this time, examples and comparative examples when the aluminum alloy film was 80 ㎛, 60 ㎛, and 40 ㎛ were divided and described in [Table 2] to [Table 4], respectively. Experimental Example 1 Experimental Example 2 Experimental Example 3 Tensile strength (N / 15mm) Moisture drying time (h) Toughness (%) Forming depth (mm) Insulation breakdown voltage (V) TD direction MD direction TS TM Example 12652601.019826016.5566Comparative Example 12962371.249826015.5566Comparative Example 42732191.2471613614.0452 Referring to the above [Table 2], it can be confirmed that Example 1 and Comparative Example 1, which consist of a double-layer stretched nylon film, showed better results in terms of moisture drying time, toughness of the nylon film, forming depth, and insulation breakdown voltage than Comparative Example 4, which consists of a single-layer stretched nylon film. In addition, in the case of Example 1, where the double-layer stretched nylon films were laminated in an alternating direction, the ratio of the tensile strength in the TD direction to the MD direction was not as large as in Comparative Example 1, where the films were laminated in a parallel direction, showing an excellent effect in the molding depth. In addition, when comparing [Table 3] to [Table 4] below with [Table 2] above, it can be seen that when the thickness of the aluminum alloy film is 80 ㎛, it exhibits a better forming depth than when it is 60 ㎛ or 40 ㎛. Experimental Example 1 Experimental Example 2 Experimental Example 3 Tensile strength (N / 15mm) Moisture drying time (h) Toughness (%) Forming depth (mm) Insulation breakdown voltage (V) TD direction MD direction TS TM Example 22552481.028826015.5566Comparative Example 22642121.245826014.0566Comparative Example 52591881.3781613613.0452 Referring to the above [Table 3], it can be confirmed that Example 2 and Comparative Example 2, which consist of a double-layer stretched nylon film, showed better results in terms of moisture drying time, toughness of the nylon film, forming depth, and insulation breakdown voltage than Comparative Example 5, which consists of a single-layer stretched nylon film. In addition, in the case of Example 2, where the double-layer stretched nylon films were laminated in an alternating direction, the ratio of the tensile strength in the TD direction to the MD direction was not as large as in Comparative Example 2, where the films were laminated in a parallel direction, showing an excellent effect in terms of the molding depth. In addition, when comparing [Table 4] below with [Table 3] above, it can be seen that when the thickness of the aluminum alloy film is 60 ㎛, a better forming depth is shown than when it is 40 ㎛. Experimental Example 1 Experimental Example 2 Experimental Example 3 Tensile strength (N / 15mm) Moisture drying time (h) Toughness (%) Forming depth (mm) Insulation breakdown voltage (V) TD direction MD direction TS TM Example 31891821.038826010.5566Comparative Example 32011591.26482609.5566Comparative Example 61831421.28981009.0452 Referring to the above [Table 4], it can be confirmed that Example 3 and Comparative Example 3, which consist of a double-layer stretched nylon film, showed better results in terms of moisture drying time, toughness of the nylon film, forming depth, and insulation breakdown voltage than Comparative Example 6, which consists of a single-layer stretched nylon film. In addition, in the case of Example 3, where the double-layer stretched nylon films were laminated in an alternating direction, the ratio of the tensile strength in the TD direction to the MD direction was not as large as in Comparative Example 3, where the films were laminated in a parallel direction, showing an excellent effect in molding depth. [Explanation of symbols] 1: Pouch film laminate 12: Surface protection layer 13: Extension auxiliary layer 14: First stretched nylon film layer 15: Second stretched nylon film layer 16a, 16b, 16c: Adhesive layer 20: Gas barrier layer 30: Sealant layer 200: Pouch-type secondary battery 210: Pouch-type case 220: Case 1 222: Cup part 224: Reception area 230: Case 2 232: Cup part 240: Bridge section 250: Sealing part 260: Electrode assembly 270: Electrode tab 272: Bipolar tab 274: Negative tab 280: Electrode Lead 282: Bipolar Lead 284: Negative lead 290: Insulation

Claims

1. A pouch film laminate comprising a sequentially laminated stretching auxiliary layer, a gas barrier layer, and a sealant layer, The above-mentioned stretching auxiliary layer comprises a first stretching nylon film layer and a second stretching nylon film layer that are sequentially laminated, The above pouch film laminate is represented by the following formula 1: TS TM Pouch film laminates having values ​​of 0.80 to 1.24: [Formula 1] TS TM = (TS T ) / (TS M ) In the above formula 1, TS T is the tensile strength (N / 15mm) in the TD direction of the above pouch film laminate, and TS M is the MD direction tensile strength (N / 15mm) of the above pouch film laminate.

2. In paragraph 1, A pouch film laminate, wherein the thickness of the above-mentioned extension auxiliary layer is 10 ㎛ to 80 ㎛.

3. In paragraph 1, A pouch film laminate, wherein the thickness of the first stretched nylon film layer is 5 ㎛ to 40 ㎛.

4. In paragraph 1, A pouch film laminate, wherein the thickness of the second stretched nylon film layer is 5 ㎛ to 40 ㎛.

5. In paragraph 1, A pouch film laminate wherein the first stretched nylon film layer and the second stretched nylon film layer are made of the same material.

6. In paragraph 1, The above pouch film laminate is T represented by the following formula 2 N Pouch film laminate having a thickness of 1.5 or more: [Formula 2] T N = (T N,A ) / (T N,B ) In the above equation 2, T N,A is the property of the above extension auxiliary layer, and T N,B is the toughness of the stretching auxiliary layer made of a single-layer stretched nylon film with a thickness of 15㎛.

7. In paragraph 1, A pouch film laminate further comprising a surface protective layer formed on the above-mentioned extension auxiliary layer.

8. In paragraph 1, A pouch film laminate wherein the thickness of the gas barrier layer is 20 ㎛ to 150 ㎛.

9. In paragraph 1, A pouch film laminate having a thickness of the sealant layer of 30 ㎛ to 130 ㎛.

10. A step of manufacturing a stretching auxiliary layer by sequentially laminating a first stretching nylon film layer and a second stretching nylon film layer; and A step of manufacturing a pouch film laminate by sequentially laminating the extension auxiliary layer, the gas barrier layer, and the sealant layer; A method for manufacturing a pouch film laminate, wherein the first stretched nylon film layer and the second stretched nylon film layer are arranged with stretching directions alternating with each other.

11. In paragraph 10, A method for manufacturing a pouch film laminate, wherein the first stretched nylon film layer and the second stretched nylon film layer are arranged so that their stretching directions intersect at an angle of 75° to 90°.

12. A pouch-type secondary battery including a pouch-type battery case manufactured by drawing and molding the pouch film laminate of clause 1.

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