Bag film laminate, bag-shaped battery case, and bag-shaped secondary battery

Abstract

The bag film laminate according to the present invention comprises a base layer, a gas barrier layer and a sealant layer stacked sequentially, wherein the base layer comprises a stretching auxiliary film disposed on the gas barrier layer and a surface protective film disposed on the stretching auxiliary film, wherein the ratio of the tensile strength in the MD direction of the stretching auxiliary film to the tensile strength in the MD direction of the surface protective film is in the range of 0.9 to 1.1, and the ratio of the tensile strength in the TD direction of the stretching auxiliary film to the tensile strength in the TD direction of the surface protective film is in the range of 0.9 to 1.1.

Description

Technical Field

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2024-0037462, filed March 18, 2024; Korean Patent Application No. 10-2024-0037463, filed March 18, 2024; Korean Patent Application No. 10-2024-0196382, filed December 24, 2024; and Korean Patent Application No. 10-2025-0034241, filed March 17, 2025, the disclosures of which are incorporated herein by reference. Technical Field

[0004] The present invention relates to pouch film laminates, pouch-type battery boxes and secondary batteries prepared by forming pouch film laminates, and more specifically, to pouch film laminates having improved formability by reducing the difference in mechanical properties between the surface protective film and the stretching auxiliary film, and pouch-type battery boxes and secondary batteries prepared by forming the pouch film laminates. Background Technology

[0005] Secondary batteries are used not only in small products such as digital cameras, P-DVDs, MP3 players, mobile phones, PDAs, portable gaming devices, power tools, and electric bicycles, but also in large products that require high output, such as electric vehicles and hybrid vehicles, as well as in power storage devices for storing surplus generated electricity or renewable energy, and in backup power storage devices.

[0006] Typically, secondary batteries are prepared by applying an electrode active material slurry to a positive current collector and a negative current collector to prepare the positive and negative electrodes respectively, stacking the positive and negative electrodes on both sides of a separator to form an electrode assembly with a predetermined shape, then housing the electrode assembly in a battery case, and sealing the battery case after injecting electrolyte.

[0007] Secondary batteries are classified into pouch-type secondary batteries, can-type secondary batteries, etc., based on the material used to house the electrode assembly. Pouch-type secondary batteries house the electrode assembly in a pouch made of a flexible polymer material. Can-type secondary batteries house the electrode assembly in a box made of a material such as metal or plastic.

[0008] The pouch-type battery case is manufactured by pressing a flexible pouch film laminate to form a cup-shaped portion. Then, once the cup-shaped portion is formed, the secondary battery is prepared by accommodating the electrode assembly within the receiving space of the cup-shaped portion and sealing the sealing portion.

[0009] Stretching in the pressing process is performed by inserting the bag film into a pressing device and applying pressure to the bag film laminate using a punch to stretch the bag film laminate. The bag film laminate typically comprises multiple layers, wherein a polymer film such as polyethylene terephthalate is laminated on one surface of a gas barrier layer formed of metal, and a sealant layer is laminated on the other surface of the gas barrier layer.

[0010] Recently, with the increasing demand for high-capacity batteries such as batteries for electric vehicles and energy storage systems (ESS), there is a need for technologies to increase energy density by increasing the amount of battery material in each pouch. As one example, a technique has been developed to increase the thickness of the aluminum in the gas barrier layer in response to the increased weight and number of batteries, thereby increasing the formability and stiffness of the pouch. However, this technique has limitations and suffers from a general problem of reduced volumetric energy density. Summary of the Invention Technical issues

[0011] One aspect of the present invention aims to provide a pouch film laminate, a pouch-type battery box, and a pouch-type secondary battery, the pouch film laminate being able to improve formability by changing the physical properties of a surface protective film included in the outer layer of the pouch structure to be similar to the physical properties of a stretching aid film. Technical solution

[0012] [1] In one aspect, the present invention provides a bag film laminate comprising a base material layer, a gas barrier layer and a sealant layer laminated sequentially, wherein the base material layer comprises a stretching auxiliary film disposed on the gas barrier layer and a surface protective film disposed on the stretching auxiliary film, the ratio of the machine direction (MD) tensile strength of the stretching auxiliary film to the MD tensile strength of the surface protective film being in the range of 0.9 to 1.1, and the ratio of the transverse direction (TD) tensile strength of the stretching auxiliary film to the TD tensile strength of the surface protective film being in the range of 0.9 to 1.1.

[0013] [2] In the bag film laminate of [1] above, the ratio of the MD elongation of the stretching auxiliary film to the MD elongation of the surface protective film can be in the range of 0.9 to 1.1, and the ratio of the TD elongation of the stretching auxiliary film to the TD elongation of the surface protective film can be in the range of 0.9 to 1.1.

[0014] [3] In the bag film laminates of [1] and / or [2] above, the MD tensile strength of the surface protective film can be in the range of 66 N / 15 mm to 95 N / 15 mm, and the MD tensile strength of the stretching auxiliary film can be in the range of 70 N / 15 mm to 90 N / 15 mm.

[0015] [4] In the bag film laminate of at least one of [1] to [3] above, the TD tensile strength of the surface protective film can be in the range of 76 N / 15 mm to 105 N / 15 mm, and the TD tensile strength of the stretching auxiliary film can be in the range of 80 N / 15 mm to 100 N / 15 mm.

[0016] [5] In the bag film laminate of at least one of [1] to [4] above, the MD elongation of the surface protective film can be in the range of 105% to 137%, and the MD elongation of the stretching auxiliary film can be in the range of 110% to 130%.

[0017] [6] In the bag film laminate of at least one of [1] to [5] above, the TD elongation of the surface protective film can be in the range of 114% to 147%, and the TD elongation of the stretching auxiliary film can be in the range of 120% to 140%.

[0018] [7] In at least one of [1] to [6] above, the thickness of the surface protective film may be from 10 μm to 35 μm.

[0019] [8] In the bag film laminate of at least one of [1] to [7] above, the thickness of the stretching auxiliary film may be from 20 μm to 45 μm.

[0020] [9] In at least one of [1] to [8] above, the thickness of the base material layer may be from 40 μm to 70 μm.

[0021]

[10] In at least one of the above [1] to [9], the thickness of the gas barrier layer may be from 70 μm to 90 μm.

[0022]

[11] In the bag film laminate of at least one of [1] to

[10] above, the thickness of the sealant layer may be from 70 μm to 90 μm.

[0023]

[12] In at least one of [1] to

[11] above, the thickness of the bag film laminate may be from 100 μm to 300 μm.

[0024]

[13] In at least one of the above [1] to

[12] , the ratio of the thickness of the bag film laminate to the thickness of the surface protective film can be in the range of 5 to 10.

[0025]

[14] In the bag film laminate of at least one of [1] to

[13] above, the ratio of the thickness of the gas barrier layer to the thickness of the surface protective film may be in the range of 2.5 to 3.3.

[0026]

[15] In the bag film laminate of at least one of [1] to

[14] above, the ratio of the thickness of the gas barrier layer to the thickness of the base material layer may be in the range of 1.4 to 1.8.

[0027]

[16] In the bag film laminate of at least one of [1] to

[15] above, the ratio of the thickness of the stretching auxiliary film to the thickness of the surface protective film may be less than or equal to 1.2.

[0028]

[17] In the bag film laminate of at least one of [1] to

[16] above, the surface protective film may include at least one selected from polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyarylate and Teflon.

[0029]

[18] In the bag film laminate of at least one of [1] to

[17] above, the stretching auxiliary film may include at least one selected from nylon 6, nylon 6,6, nylon MXD6 (poly(xylene adipamide)), nylon 4, nylon 4,6 and nylon 4,10.

[0030]

[19] In the bag film laminate of at least one of [1] to

[18] above, the gas barrier layer may include at least one selected from aluminum, copper, stainless steel, nickel, titanium and Invar alloy.

[0031]

[20] In the bag film laminate of at least one of [1] to

[19] above, the sealant layer may include at least one selected from polypropylene, polyethylene terephthalate, polyethylene, polycarbonate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyarylate, Teflon and glass fiber.

[0032]

[21] In the bag film laminate of at least one of [1] to

[20] above, the sealant layer includes a first sealant layer disposed in contact with the gas barrier layer, a second sealant layer laminated on the first sealant layer, and a third sealant layer laminated on the second sealant layer.

[0033]

[22] In another aspect, the present invention provides a pouch-type battery case, which is prepared by stretching a pouch film laminate of at least one of [1] to

[21] above.

[0034]

[23] In another aspect, the present invention provides a pouch-type secondary battery comprising the pouch-type battery case described above

[22] . Beneficial effects

[0035] The pouch film laminate according to the invention is characterized by including a surface protective film having a tensile strength similar to that of the stretching auxiliary film, and as described above, in the case of using a pouch-type battery case with a small difference in mechanical properties between the two layers set to their outermost surface, the formability is significantly improved by preventing pinholes or breaks caused by differences in the physical properties of the individual layers, thus ensuring sufficient forming depth. Attached Figure Description

[0036] The following accompanying drawings illustrate preferred embodiments of the invention by way of example, and together with the following detailed description of the invention, are provided to enable a further understanding of the technical concept of the invention, and therefore the invention should not be interpreted solely by the contents of such drawings.

[0037] Figure 1 This is a cross-sectional view of the bag film laminate according to the present invention.

[0038] Figure 2 This is an exploded assembly diagram of the pouch-type secondary battery according to the present invention. Detailed Implementation

[0039] It will be understood that the words or terms used in the specification and claims should not be interpreted as having the meaning defined in a commonly used dictionary, and it will be further understood that, based on the inventor's ability to appropriately define the meaning of words or terms in order to best illustrate the principles of the invention, the words or terms should be interpreted as having a meaning consistent with their meaning in the context of the relevant field and technical concept of the invention.

[0040] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to limit the invention. In this specification, singular terms may include plural forms unless otherwise stated. It will be further understood that, when used in this specification, the terms “comprising” and / or “including” indicate the presence of a stated component but do not exclude the presence or addition of one or more other components.

[0041] In this specification, MD (machine direction) refers to the longitudinal direction of the stretching auxiliary film and the surface protective film, and TD (transverse direction) refers to the width direction of the stretching auxiliary film and the surface protective film.

[0042] The MD tensile strength (N / 15 mm) of the surface protective film and the stretching auxiliary film according to the present invention can be measured as the strength at which the surface protective film and the stretching auxiliary film break when each is cut into lengths (MD) × widths (TD) of 130 mm × 15 mm, fixed to a universal testing machine (UTM) with a gripping gap of 50 mm and stretched at a tensile speed of 5 mm / min. The MD elongation (%) of the surface protective film and the stretching auxiliary film can be calculated as the value obtained by dividing the gripping gap at the point of breakage by the gripping gap before stretching (50 mm) and then multiplying by 100.

[0043] The TD tensile strength (N / 15 mm) of the surface protective film and the stretching auxiliary film according to the present invention can be measured as the strength at which the surface protective film and the stretching auxiliary film break when each is cut into lengths (MD) × widths (TD) of 15 mm × 130 mm, fixed to the UTM with a gripping gap of 50 mm, and stretched at a stretching speed of 5 mm / min. The TD elongation (%) of the surface protective film and the stretching auxiliary film can be calculated as the value obtained by dividing the gripping gap at the time of breakage by the gripping gap before stretching (50 mm) and then multiplying by 100.

[0044] The invention will be described in more detail below.

[0045] The bag film laminate according to the invention includes at least one of the following disclosed configurations, and may include any combination of technically possible configurations among the following configurations.

[0046] <Bag film laminate>

[0047] First, the bag film laminate according to the present invention will be described.

[0048] The bag film laminate 100 according to the present invention includes a base material layer 110, a gas barrier layer 120 and a sealant layer 130 laminated sequentially, wherein the base material layer 110 includes a stretching auxiliary film 114 disposed on the gas barrier layer 120 and a surface protective film 112 disposed on the stretching auxiliary film 114.

[0049] In the following text, reference will be made to Figure 1 The various configurations of the bag film laminate according to the present invention will be described in more detail.

[0050] (1) Basic material layer

[0051] According to the invention, the base material layer 110 is formed as the outermost layer of the pouch film laminate 100 to protect the secondary battery from friction and impact with the outside. The base material layer 110 is formed of a polymer, such that the base material layer 110 can electrically insulate the electrode assembly from the outside.

[0052] The base material layer 110 may include a surface protective film 112 and a stretching auxiliary film 114. In this case, the surface protective film 112 may be the outermost layer of the bag film laminate, and the stretching auxiliary film 114 may be a layer disposed between the surface protective film 112 and the gas barrier layer 120. The surface protective film 112 and the stretching auxiliary film 114 may be formed of materials with different materials and / or physical properties. A joint may exist between the surface protective film 112 and the stretching auxiliary film 114. This means that the surface protective film 112 and the stretching auxiliary film 114 are different layers from each other and can be formed separately.

[0053] The surface protective film 112 according to the invention can be the outermost layer of the bag film laminate as described above. In this case, the surface protective film 112 is used to protect the surface of the bag from the influence of the external environment, wherein the surface protective film 112 can prevent moisture from penetrating from the outside.

[0054] The surface protective film 112 may be formed from at least one material selected from polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyarylate, Teflon, and glass fiber. Specifically, the surface protective film 112 may include, but is not limited to, at least one selected from polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, which have abrasion resistance and heat resistance.

[0055] If necessary, the surface protective film 112 may include additives. By including additives in the surface protective film 112, the physical properties of the surface protective film 112 can be modified. For example, at least one of carbon fiber, glass fiber, and aramid fiber can be added as an additive for adjusting the tensile strength of the surface protective film 112.

[0056] The thickness of the surface protective film 112 can be from 10 μm to 35 μm, preferably from 20 μm to 30 μm, more preferably from 22 μm to 28 μm, and even more preferably from 24 μm to 26 μm. When the thickness of the surface protective film 112 meets the above ranges, since the surface protective film has a similar thickness to the stretching auxiliary film 114 according to the invention, the difference in tensile strength is reduced, preventing breakage due to differences in the physical properties between the two films. Furthermore, since durability is improved in structures requiring deep forming under pressure, the formability of the bag can be improved, and problems such as film tearing or wrinkling during forming can be prevented.

[0057] As described above, the stretching aid film 114 according to the present invention can also be a layer disposed between the surface protective film 112 and the gas barrier layer 120. The stretching aid film 114 has a high elongation, and therefore, since the stretching aid film 114 stretches but is not easily torn when deformation is applied, the stretching aid film 114 assists in the stretching of the bag film laminate by preventing easy breakage during the forming process of the bag film laminate.

[0058] The stretching auxiliary film 114 may comprise a polyamide-based film. The stretching auxiliary film 114 may comprise, but is not limited to, at least one selected from nylon 6, nylon 6,6, nylon MXD6 (poly(xylene adipamide)), nylon 4, nylon 4,6, and nylon 4,10. Specifically, to enable the stretching auxiliary film 114 to have a melting temperature greater than or equal to 240°C, the stretching auxiliary film 114 may comprise nylon 6,6 and / or nylon MXD6.

[0059] The thickness of the stretching aid membrane 114 can be from 20 μm to 45 μm, preferably from 20 μm to 30 μm, more preferably from 22 μm to 28 μm, and even more preferably from 24 μm to 26 μm. When the thickness of the stretching aid membrane 114 meets the above numerical range, since the elongation is increased while ensuring tensile strength, it is balanced with the formability of the gas barrier layer to prevent damage during stretching, and thus the formability of the bag can be ensured, and the reduction in the volumetric energy density of the secondary battery due to excessive increase in the thickness of the bag film laminate can be prevented.

[0060] The ratio of the thickness of the stretching auxiliary film 114 to the thickness of the surface protective film 112 can be less than or equal to 1.2, preferably less than or equal to 1.2, less than or equal to 1.1, or less than or equal to 1.05, and greater than or equal to 0.5, greater than or equal to 0.6, greater than or equal to 0.7, greater than or equal to 0.8, or greater than or equal to 0.9, and more preferably in the range of 0.9 to 1.05. When the above ranges are met, the film is stretched uniformly because stress is not concentrated in specific areas due to the uniform distribution of tensile stress, and delamination is prevented due to the uniform adhesion between the two films, thus improving formability and ensuring a high forming depth.

[0061] In the bag film laminate 100 according to the present invention, the ratio of the MD tensile strength of the stretching aid film 114 to the MD tensile strength of the surface protective film 112 is in the range of 0.9 to 1.1, and the ratio of the TD tensile strength is in the range of 0.9 to 1.1. When the ratio of the MD tensile strength and TD tensile strength of the stretching aid film 114 to the surface protective film 112 satisfies the above range, the difference in mechanical properties between the surface protective film 112 and the stretching aid film 114 is reduced, thereby preventing breakage due to differences in physical properties during the bag forming process, and thus improving the formability of the bag.

[0062] The MD tensile strength ratio of the stretching auxiliary film 114 to the surface protective film 112 can specifically be in the range of 0.95 to 1.05, more specifically in the range of 0.98 to 1.02, and the TD tensile strength ratio of the stretching auxiliary film 114 to the surface protective film 112 can specifically be in the range of 0.95 to 1.05, more specifically in the range of 0.98 to 1.02.

[0063] Furthermore, the MD elongation ratio of the stretching aid film 114 to the surface protective film 112 is in the range of 0.9 to 1.1, and the TD elongation ratio is in the range of 0.9 to 1.1. When the MD elongation ratio and TD elongation ratio of the stretching aid film 114 to the surface protective film 112 meet the above ranges, the difference in tensile properties between the laminated structural layers is reduced, so the two films deform uniformly during stretching, and wrinkles caused by excessive shrinkage or elongation can be prevented, and stress concentration that may occur at the film interface during forming can be reduced, thereby preventing layer delamination.

[0064] The MD elongation ratio of the stretching auxiliary film 114 to the surface protective film 112 can specifically be in the range of 0.95 to 1.05, more specifically in the range of 0.98 to 1.02, and the TD elongation ratio of the stretching auxiliary film 114 to the surface protective film 112 can specifically be in the range of 0.95 to 1.05, more specifically in the range of 0.98 to 1.02.

[0065] The surface protective film 112 has a tensile strength of MD ranging from 66 N / 15 mm to 95 N / 15 mm, particularly from 70 N / 15 mm to 90 N / 15 mm, and even more particularly from 76 N / 15 mm to 84 N / 15 mm, and the tensile auxiliary film 114 has a tensile strength of MD ranging from 70 N / 15 mm to 90 N / 15 mm, particularly from 72 N / 15 mm to 88 N / 15 mm, and even more particularly from 75 N / 15 mm to 85 N / 15 mm.

[0066] Furthermore, the TD tensile strength of the surface protective film 112 can be in the range of 76 N / 15 mm to 105 N / 15 mm, particularly in the range of 81 N / 15 mm to 100 N / 15 mm, and even more particularly in the range of 86 N / 15 mm to 95 N / 15 mm, and the TD tensile strength of the stretching auxiliary film 114 can be in the range of 80 N / 15 mm to 100 N / 15 mm, particularly in the range of 82 N / 15 mm to 98 N / 15 mm, and even more particularly in the range of 85 N / 15 mm to 95 N / 15 mm.

[0067] When the MD tensile strength or TD tensile strength of the surface protective film 112 and the stretching auxiliary film 114 meet the above range, the fatigue resistance and puncture resistance of the cup after forming can be enhanced, and even if a certain level or higher tensile load is applied to the bag for bag forming, the problem of bag film laminate 100 breaking or producing pinholes can be prevented.

[0068] The surface protective film 112 has an MD elongation in the range of 105% to 137%, particularly in the range of 110% to 130%, and even more particularly in the range of 114% to 126%, and the stretching auxiliary film 114 has an MD elongation in the range of 110% to 130%, particularly in the range of 112% to 127%, and even more particularly in the range of 115% to 125%.

[0069] The TD elongation of the surface protective film 112 can be in the range of 114% to 147%, particularly in the range of 120% to 140%, and even more particularly in the range of 124% to 137%, and the TD elongation of the stretching auxiliary film 114 can be in the range of 120% to 140%, particularly in the range of 122% to 138%, and even more particularly in the range of 125% to 135%.

[0070] When the MD elongation and TD elongation of the surface protective film 112 and the stretching auxiliary film 114 meet the above ranges, the gas barrier layer is well maintained, thus improving the formability can be achieved.

[0071] Since the tensile strength and elongation of the surface protective film 112 and the stretching auxiliary film 114 vary depending on the type of film, the thickness of the film and / or the thickness of the adhesive layer, the surface protective film 112 and the stretching auxiliary film 114 with the desired tensile strength and elongation can be formed by appropriately adjusting the type of film, the thickness of the film and / or the thickness of the adhesive layer.

[0072] According to an embodiment, the surface protective film 112 may be a polyethylene terephthalate film, and the stretching auxiliary film 114 may be a nylon film. In this case, it is desirable that the nylon film is disposed toward the gas barrier layer 120, i.e., disposed on the inside, while the polyethylene terephthalate film is disposed toward the surface of the battery compartment.

[0073] Because polyethylene terephthalate (PET) possesses excellent durability and electrical insulation properties, its durability and insulation performance are excellent when the PET film is positioned facing the surface. However, regarding the PET film, due to its weak adhesion to the aluminum alloy film constituting the gas barrier layer 120 and its different tensile properties, delamination may occur between the base material layer and the gas barrier layer 120 during the forming process when the PET film is positioned facing the gas barrier layer 120. Furthermore, uneven stretching of the gas barrier layer 120 may lead to reduced formability. Conversely, because the nylon film has similar tensile properties to the aluminum alloy film constituting the gas barrier layer 120, improved formability can be achieved when the nylon film is positioned between the PET and the gas barrier layer 120.

[0074] The base material layer 110 may have a composite layer structure formed by laminating two or more materials respectively. An adhesive layer may be additionally formed between the corresponding layers in the composite layer structure. The adhesive layer may be formed by applying an adhesive commonly used in this invention, such as a urethane-based adhesive. In this case, the thickness of the adhesive layer may be from 1 μm to 8 μm, particularly from 1 μm to 5 μm, and more particularly from 2 μm to 4 μm. The base material layer 110 includes a surface protective film and a stretching auxiliary film, and may preferably further include an adhesive layer disposed between the surface protective film and the stretching auxiliary film. Specifically, the adhesive layer may be formed between the surface protective film 112 and the stretching auxiliary film 114, and for example, the base material layer 110 may have a structure in which the surface protective film / adhesive layer / stretching auxiliary film are laminated sequentially.

[0075] In this case, the thickness of the base material layer 110 can be 40 μm to 70 μm, particularly 45 μm to 60 μm, and more particularly 48 μm to 58 μm. When the thickness of the base material layer 110 meets the above range, durability, insulation performance, and formability are excellent. If the thickness of the base material layer 110 is too thin, durability may decrease, and the base material layer may be damaged during the molding process. If the thickness is too thick, formability may decrease, the total thickness of the pouch film laminate may increase, and the battery housing space may decrease, thus reducing energy density. In this case, the thickness of the base material layer 110 can be the thickness of the adhesive layer that may be included in the base material layer 110, and can be the thickness of the adhesive layer that adheres the gas barrier layer 120 and the base material layer 110. As described above, when the thickness of the base material layer 100 is the thickness of the adhesive layer that includes the base material layer 100 and the adhesive layer that adheres the gas barrier layer 120 and the base material layer 110, a more pronounced effect can be obtained.

[0076] (2) Gas barrier layer

[0077] According to the invention, the gas barrier layer 120 is laminated between the base material layer 110 and the sealant layer 130 to ensure the mechanical strength of the bag, block the inflow and outflow of gas or moisture from outside the secondary battery, and prevent electrolyte from leaking from the inside of the bag-shaped battery box.

[0078] The gas barrier layer 120 can be formed of a metal. For example, the gas barrier layer can be a thin film of at least one metal selected from aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti), and Invar, but is not limited thereto.

[0079] The gas barrier layer 120 can be formed of an aluminum alloy thin film. When the gas barrier layer 120 is formed using an aluminum alloy thin film, it is lightweight while ensuring mechanical strength above a predetermined level, compensating for the electrochemical performance of the electrode assembly and electrolyte, and ensuring heat dissipation performance. The aluminum alloy thin film may include elements other than aluminum (Al). For example, the aluminum alloy thin film may include at least one selected from iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0080] Typically, the gas barrier layer 120 is formed to a thickness of 30 μm to 50 μm. However, when the thickness of the gas barrier layer is in the range of 30 μm to 50 μm, even when stretching the pouch film laminate, there are limitations in increasing the depth of the cup-shaped portion or making the outer wall of the cup-shaped portion nearly vertical, and there are also limitations in reducing the radius of curvature of the rounded corners of the cup-shaped portion. Furthermore, due to the low puncture strength, there is a problem that the internal electrode assembly is easily damaged when the battery box is subjected to external impacts.

[0081] Therefore, to improve this problem in the present invention, the gas barrier layer 120 is formed with a thickness of 70 μm to 90 μm, particularly 75 μm to 85 μm, and even more particularly 78 μm to 82 μm. When the thickness of the gas barrier layer meets the above range, due to the improved formability of the gas barrier layer, the cup-shaped portion can be formed deeper when stretching the pouch film laminate, and the radius of curvature of the edge of the cup-shaped portion can also be reduced. Therefore, due to the increased volume of the accommodating space, more electrodes and separators can be stacked in the electrode assembly housed therein, and the volumetric energy efficiency can be increased. However, when the thickness of the gas barrier layer is greater than 90 μm, the volumetric energy density of the secondary battery may decrease because the thickness of the pouch film laminate may be excessively increased.

[0082] The ratio of the thickness of the gas barrier layer to the thickness of the surface protective film can be in the range of 2.5 to 3.3. Preferably, this ratio can be greater than or equal to 2.50, greater than or equal to 2.55, greater than or equal to 2.60, greater than or equal to 2.65, greater than or equal to 2.70, greater than or equal to 2.75, greater than or equal to 2.80, greater than or equal to 2.85, greater than or equal to 2.90, greater than or equal to 2.95, or greater than or equal to 3.00, and can be less than or equal to 3.30. More preferably, this ratio can be in the range of 3.00 to 3.30. When the above ranges are met, due to the balance of the thicknesses of the surface protective film and the gas barrier layer, the tensile force is uniformly distributed during the forming process to facilitate deformation, and therefore, a higher forming depth can be ensured.

[0083] The ratio of the gas barrier layer thickness to the base material layer thickness can be in the range of 1.4 to 1.8, specifically in the range of 1.4 to 1.7. When this range is met, a higher forming depth can be ensured because cracking is prevented during forming.

[0084] (3) Sealant layer

[0085] The sealant layer 130 according to the invention is used to completely seal the interior of the pouch battery case by thermal bonding to each other at the sealing portion when the pouch battery case containing the electrode assembly is sealed. For this purpose, the sealant layer 130 can be formed of a material with excellent thermal bonding strength.

[0086] The sealant layer 130 can be formed of a material with insulating, corrosion-resistant, and sealing properties. Specifically, since the sealant layer 130 is in direct contact with the electrode components and / or electrolyte inside the pouch cell, it can be formed of a material with insulating and corrosion-resistant properties. Furthermore, since the sealant layer 130 completely seals the interior of the pouch cell to prevent movement of matter between the interior and exterior, it can be formed of a material with high sealing properties (e.g., excellent thermal bonding strength). To ensure these insulating, corrosion-resistant, and sealing properties, the sealant layer 130 can be formed of a polymer material.

[0087] The sealant layer 130 may include at least one selected from polypropylene, polyethylene terephthalate, polyethylene, polycarbonate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyarylate, Teflon, and glass fiber, and may preferably include polyolefin-based resins such as polypropylene and / or polyethylene. In this case, polypropylene may include cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butene-ethylene terpolymer.

[0088] The thickness of the sealant layer 130 can be from 70 μm to 90 μm, particularly from 75 μm to 85 μm, and even more particularly from 78 μm to 82 μm. When the thickness of the sealant layer meets the above range, it has the effect of ensuring the sealing strength of the sealed part while ensuring the formability of the bag film laminate.

[0089] The sealant layer 130 may include a first sealant layer disposed in contact with the gas barrier layer, a second sealant layer laminated on the first sealant layer, and a third sealant layer laminated on the second sealant layer.

[0090] According to embodiments of the present invention, the first sealant layer may comprise polypropylene, and preferably, to ensure long-term adhesion between the gas barrier layer and the first sealant layer, the first sealant layer may comprise acid-modified polypropylene (PPa). In this document, the acid-modified polypropylene may be maleic anhydride polypropylene (MAH PP).

[0091] According to embodiments of the present invention, the second sealant layer can be formed of a material having insulating, corrosion-resistant, and sealing properties. Preferably, the second sealant layer can be formed of at least one material selected from polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyarylate, Teflon, and glass fiber. Preferably, the second sealant layer can be formed of a polyolefin-based resin such as polypropylene (PP) and / or polyethylene (PE). In this case, polypropylene can include cast polypropylene, acid-modified polypropylene, polypropylene-ethylene copolymer, and / or polypropylene-butene-ethylene terpolymer. Herein, acid-modified polypropylene can be maleic anhydride polypropylene (MAH PP). More preferably, the second sealant layer can include cast polypropylene (CPP) having high tensile strength and heat-sealing properties.

[0092] According to embodiments of the present invention, the third sealant layer may comprise polypropylene, preferably a random copolymer of polypropylene, more preferably at least one selected from ethylene-propylene random copolymers and butene-propylene random copolymers, and even more preferably ethylene-propylene random copolymers. When the above conditions are met, due to the high melt flow rate (MFR) and low melting point, the desired seal thickness can be achieved quickly when the same amount of heat is applied. Therefore, compared to the case comprising polypropylene homopolymer, the sealing time can be shortened even without increasing the sealing temperature, and the processing time of the secondary battery can be shortened, thus improving productivity and processability. Furthermore, due to the high thermal bonding strength of the third sealant layer, the pouch-type battery case can have excellent sealing performance.

[0093] As described above, the bag film laminate according to the present invention can be prepared by methods known in the art for preparing bag film laminates. For example, the bag film laminate of the present invention can be prepared by attaching a base material layer 110 to the upper surface of a gas barrier layer 120 using an adhesive, and forming a sealant layer 130 on the lower surface of the gas barrier layer 120 by co-extrusion or adhesive layer, but the present invention is not limited thereto.

[0094] The total thickness of the bag film laminate can be from 100 μm to 300 μm, particularly from 160 μm to 250 μm, and even more particularly from 200 μm to 230 μm. When the thickness of the bag film laminate meets the above range, the forming depth can be increased while minimizing the reduction in sealing durability or the reduction in battery housing space caused by the increase in the thickness of the bag laminate.

[0095] The ratio of the thickness of the bag film laminate to the thickness of the surface protective film can be in the range of 5 to 10, preferably greater than or equal to 6.0, 6.5, 7.5, or 8.0, and can be less than or equal to 10, 9.5, or 9.0, and more preferably in the range of 8.0 to 9.0. When the above ranges are met, since the ratio of the thickness of the bag film laminate to the thickness of the surface protective film is appropriate, tensile deformation is less likely to occur, preventing wrinkles during the forming process, thus increasing the forming depth, and resulting in excellent strength. Furthermore, when the above conditions are met, since most of the stretching occurs at the edges and / or corners, which are areas of concentrated tensile stress during bag forming, they are formed thinner than other parts and are more susceptible to external impacts. Therefore, by preventing excessive reduction in the thickness of the edges and / or corners, superior strength can be achieved.

[0096] <Pouch-type secondary batteries>

[0097] Next, we will refer to Figure 2 The pouch-type secondary battery according to the present invention will be described in more detail.

[0098] The pouch-type secondary battery 200 according to the present invention includes a pouch-type battery case 210 for accommodating electrode assemblies. The pouch-type battery case 210 includes a pouch film laminate 100, and the pouch film laminate 100 includes a base material layer 110, a gas barrier layer 120 and a sealant layer 130 laminated in sequence. The base material layer includes a surface protective film 112 and a stretching auxiliary film 114, and the stretching auxiliary film 114 is disposed between the surface protective film 112 and the gas barrier layer 120.

[0099] (1) Pouch-type battery box

[0100] The pouch-type battery case 210 according to the present invention can internally house the electrode assembly 260. The pouch-type battery case 210 can be manufactured by forming the pouch film laminate of the present invention as described above. Since the detailed configuration and physical properties of the pouch film laminate are the same as described above, detailed description is omitted.

[0101] The pouch-type battery case 210 can be prepared by stretching and extending the pouch film laminate using a punch or similar means. Therefore, the pouch-type battery case 210 may include a cup-shaped portion 222 and a receiving portion 224. The receiving portion 224 is a location for receiving electrode assemblies, wherein the receiving portion 224 can refer to a receiving space formed in a recessed shape within the cup-shaped portion 222 when the cup-shaped portion 222 is formed.

[0102] According to an 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 FIG3. The first case 220 includes a receiving portion 224 capable of accommodating an electrode assembly 260, and the second case 230 can cover the receiving portion 224 from the top, such that the electrode assembly 260 does not detach to the outside of the battery case 210. As illustrated in FIG3, the first case 220 and the second case 230 can be prepared by connecting one side of them to each other, but the invention is not limited thereto, and the first case and the second case can be prepared in various ways, for example, the first case and the second case can be separated from each other and prepared separately.

[0103] According to another embodiment of the invention, when the cup-shaped portions are formed on a pouch film laminate, two symmetrical cup-shaped portions 222 and 232 can be stretched adjacent to each other on a pouch film laminate. In this case, as illustrated in FIG. 3, the cup-shaped portions 222 and 232 can be formed in a first box 220 and a second box 230, respectively. After the electrode assembly 260 is accommodated in the receiving portion 224 provided in the cup-shaped portion 222 of the first box 220, the bridging portion 240 formed between the two cup-shaped portions 222 and 232 can be folded so that the two cup-shaped portions 222 and 232 face each other. In this case, the cup-shaped portion 232 of the second box 230 can accommodate the electrode assembly 260 from above. Therefore, since the two cup-shaped portions 222 and 232 accommodate one electrode assembly 260, an electrode assembly 260 with a greater thickness can be accommodated compared to when there is only one cup-shaped portion 222. Furthermore, since one edge of the secondary battery 200 is formed by folding the pouch-shaped battery case 210, the number of edges to be sealed can be reduced when a sealing process is performed later. Therefore, the processing speed of the pouch-shaped secondary battery 200 can be increased, and the number of sealing processes can be reduced.

[0104] The pouch-type battery case 210 can be sealed while housing the electrode assembly 260, exposing a portion of the electrode leads 280, i.e., the terminal portion, as described later. Specifically, when the electrode leads 280 are connected to the electrode tabs 270 of the electrode assembly 260 and an insulating portion 290 is formed in this portion of the electrode leads 280, the electrode assembly 260 is housed in a receiving portion 224 provided in the cup-shaped portion 222 of the first case 220, and the second case 230 can cover the receiving portion 224 from the top. Subsequently, electrolyte is injected into the receiving portion 224, and sealing portions 250 formed on the edges of the first case 220 and the second case 230 can be sealed.

[0105] The sealing portion 250 can be used to seal the receiving portion 224. Specifically, the sealing portion 250 can seal the receiving portion 224 while being formed along its edge. The sealing temperature of the sealing portion 250 can be in the range of 180°C to 250°C, particularly in the range of 200°C to 250°C, and even more particularly in the range of 210°C to 240°C. When the sealing temperature meets the above numerical range, the pouch-type battery box 210 can ensure sufficient sealing strength through thermal bonding.

[0106] (2) Electrode assembly

[0107] The electrode assembly 260 according to the invention can be inserted into the pouch battery case 210 and can be sealed by the pouch battery case 210 after electrolyte is injected.

[0108] Electrode assembly 260 can be formed by sequentially stacking a positive electrode, a spacer, and a negative electrode. Specifically, electrode assembly 260 may include two types of electrodes, such as a positive electrode and a negative electrode, and a spacer disposed between the electrodes to insulate them from each other.

[0109] The positive and negative electrodes can be structures in which an active material slurry is applied, respectively, to an electrode current collector in the form of a metal foil or mesh, including aluminum and copper. The slurry is typically formed by stirring granular active material, auxiliary conductors, binders, and conductive agents with a solvent added. The solvent can be removed in subsequent processes.

[0110] A slurry containing electrode active materials, binders, and / or conductive agents is applied to a positive current collector and a negative current collector to prepare positive and negative electrodes. Electrode assemblies 260 can be prepared in a predetermined shape by stacking the positive and negative electrodes on both sides of a separator. The types of electrode assemblies 260 may include, but are not limited to, stacked, wound, and stacked and folded types.

[0111] Electrode assembly 260 may include electrode tabs 270.

[0112] Electrode tab 270 is connected to each of the positive and negative electrodes of electrode assembly 260 and protrudes from the electrode assembly 260 to the outside, such that electrode tab 270 can be a path through which electrons can move between the inside and outside of electrode assembly 260. The electrode current collector included in electrode assembly 260 may include a portion to which electrode active material is applied and an end portion to which no electrode active material is applied, i.e., an uncoated portion. Electrode tab 270 can be formed by cutting the uncoated portion, or by connecting individual conductive members to the uncoated portion by means of ultrasonic welding, etc. Figure 1As illustrated, the electrode tabs 270 may protrude in different directions along the electrode assembly 260, but are not limited thereto, and may be formed to protrude in various directions, for example, the electrode tabs may protrude side by side from one side of the electrode assembly in the same direction.

[0113] (3) Electrode leads

[0114] The electrode lead 280 according to the present invention can supply power to the outside of the secondary battery 200. The electrode lead 280 can be connected to the electrode contacts 270 of the electrode assembly 260 by spot welding or the like.

[0115] Electrode leads 280 are connected to electrode assemblies 260 and can protrude to the outside of the pouch-type battery case 210 via sealing portions 250. Specifically, one end of electrode lead 280 can be connected to electrode assemblies 260, particularly electrode tabs 270, and the other end of electrode lead 280 can protrude to the outside of the pouch-type battery case 210.

[0116] Electrode leads 280 may include a positive lead 282 and a negative lead 284. One end of the positive lead 282 is connected to the positive terminal 272 and extends along the protruding direction of the positive terminal 272. One end of the negative lead 284 is connected to the negative terminal 271 and extends along the protruding direction of the negative terminal 271. The other ends of both the positive lead 282 and the negative lead 284 may protrude to the outside of the battery case 210. Therefore, the power generated inside the electrode assembly 260 can be supplied to the outside. Furthermore, since the positive terminal 272 and the negative terminal 271 are formed to protrude in different directions, the positive lead 282 and the negative lead 284 may also extend in different directions. The materials of the positive lead 282 and the negative lead 284 may be different from each other. That is, the positive electrode lead 282 can be formed of the same aluminum (Al) material as the positive current collector, and the negative electrode lead 284 can be formed of the same copper (Cu) material as the negative current collector or nickel (Ni) coated copper material. Since a portion of the electrode lead 280 protruding to the outside of the battery case 210 becomes a terminal portion, the electrode lead 280 can be electrically connected to an external terminal.

[0117] (4) Insulation part

[0118] The insulating portion 290 according to the invention prevents the electricity generated by the electrode assembly 260 from flowing through the electrode lead 280 to the battery case 210 and can maintain the seal of the battery case 210. For this purpose, the insulating portion 290 can be formed of an insulator that is non-conductive and does not conduct electricity well. Typically, insulating tapes or films that are easy to attach to the electrode lead 280 and are relatively thin are widely used as the insulating portion 290, but the invention is not limited to this, and any component capable of insulating the electrode lead 280 can be used.

[0119] The insulating portion 290 may be configured to surround the outer peripheral surface of the electrode lead 280. Specifically, 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 disposed between the electrode lead 280 and the pouch-type battery case 210. The insulating portion 290 may be limited at the sealing portion 250 located at the thermal fusion of the first case 220 and the second case 230 of the pouch-type battery case 210, and may adhere the electrode lead 280 to the battery case 210.

[0120] (5) Electrolytes

[0121] The pouch-type secondary battery 200 according to the invention may further include an electrolyte (not shown) injected into the pouch-type battery case 210. The electrolyte according to the invention is used to move lithium ions generated by the electrochemical reaction of the electrodes during charging / discharging of the secondary battery 200. The electrolyte may comprise a non-aqueous organic electrolyte solution as a mixture of lithium salt and organic solvent, or a polymer using a polymer electrolyte. Furthermore, the electrolyte may comprise a sulfide-based, oxide-based, or polymer-based solid electrolyte, and the solid electrolyte may have flexibility that allows it to be easily deformed by external forces.

[0122] If pressure is applied due to external forces or gas generation, delamination may occur at interfaces with relatively weak adhesion in the sealed battery case 210. For example, delamination can occur along the interface between thermally bonded sealant layers. However, for battery cases prepared using the pouch film laminate of the present invention, the adhesion at the interface remains high due to the smooth thermal bonding between sealant layers with improved flow characteristics during melting, and thus excellent sealing strength can be achieved.

[0123] The invention will be described in detail below with reference to specific examples. However, the examples given below are merely illustrative and the scope of the invention is not limited thereto. It will be apparent to those skilled in the art that various modifications and variations can be made within the scope and spirit of the invention. Such modifications and variations fall within the scope of the claims included herein.

[0124] Example 1

[0125] After applying a 3 μm thick urethane adhesive between a 25 μm thick nylon film and a 25 μm thick polyethylene terephthalate film to form a 3 μm thick first adhesive layer, thermal lamination is performed to form a base material layer. In this case, films having the tensile strength and elongation described in Tables 1 and 2 below are used as the nylon film and the polyethylene terephthalate film.

[0126] Then, a urethane adhesive is applied to one surface of an 80 μm thick aluminum alloy as a gas barrier layer to form a 3 μm thick second adhesive layer, and the base material layer prepared above is laminated on the second adhesive layer and then subjected to heat lamination.

[0127] Next, a 30 μm thick first sealant layer comprising acid-modified polypropylene (PPa), a 30 μm thick second sealant layer comprising cast polypropylene (PP), and a 20 μm thick third sealant layer comprising ethylene-propylene random copolymer are co-extruded on the other surface of the gas barrier layer to prepare a bag film laminate sequentially laminated with a surface protective film / first adhesive layer / stretching aid film / second adhesive layer / gas barrier layer / first sealant layer / second sealant layer / third sealant layer.

[0128] Examples 2 through 4 and comparison examples 1 through 3

[0129] Except for using films with tensile strength and elongation of MD and TD as shown in Table 1 and Table 2 below as nylon films and polyethylene terephthalate films respectively, the bag film laminates of Examples 2 to 4 and Comparative Examples 1 to 3 were prepared in the same manner as in Example 1.

[0130] Comparison Example 4

[0131] Except that the thickness of the surface protective film is 12 μm and the thickness of the gas barrier layer is 60 μm, the bag film laminate is prepared in the same manner as in Example 1.

[0132] Comparison Example 5

[0133] Except for the surface protective film having a thickness of 12 μm, the stretching auxiliary film having a thickness of 15 μm, and the gas barrier layer, the first sealant layer, and the third sealant layer having a thickness of 40 μm, and excluding the second sealant layer, a bag film laminate consisting of a surface protective film, a first adhesive layer, a stretching auxiliary film, a second adhesive layer, a gas barrier layer, a first sealant layer, and a third sealant layer is prepared in the same manner as in Example 1.

[0134] [Table 1]

[0135] [Table 2]

[0136] Experimental Example: Evaluation of Maximum Forming Depth

[0137] The maximum forming depth of each bag film laminate prepared in Examples 1 to 4 and Comparative Examples 1 to 5 was measured.

[0138] Specifically, when the bag film laminate was cut into pieces with a width of 266 mm and a length of 200 mm and then cold-formed to form a cup-shaped portion with a width of 90 mm and a length of 160 mm, the forming depth of the bag film laminate before fracture was defined as the maximum forming depth (unit: mm). After preparing 15 bag film laminates each of Examples 1 to 4 and Comparative Examples 1 to 5, and performing 15 maximum forming depth measurement experiments, the average value of the maximum forming depth is shown in Table 3 below.

[0139] [Table 3]

[0140] According to Table 3, for Examples 1 to 4 where the ratio of the tensile strength in the MD direction or the tensile strength in the TD direction of the nylon film to the tensile strength in the MD direction or the tensile strength in the TD direction of the PET film is in the range of 0.9 to 1.1, the forming depth of Examples 1 to 4 is greater than that of Comparative Examples 1 to 5. Therefore, it can be confirmed that the formability of the bag film laminates prepared in Examples 1 to 4 is better than that of the bag film laminates prepared in Comparative Examples 1 to 5.

[0141] [Description of reference numerals in the attached figures]

[0142] 100: Bag film laminate

[0143] 110: Basic material layer

[0144] 112: Surface protective film

[0145] 114: Stretch-assisted membrane

[0146] 120: Gas Barrier Layer

[0147] 130: Sealant layer

[0148] 200: Pouch-type secondary battery

[0149] 210: Bag-type box

[0150] 220: First box

[0151] 222: Cup-shaped part

[0152] 224: Accommodation section

[0153] 230: Second box

[0154] 232: Cup-shaped part

[0155] 240: Bridging section

[0156] 250: Sealing part

[0157] 260: Electrode assembly

[0158] 270: Electrode contacts

[0159] 271: Negative electrode connector

[0160] 272: Positive electrode connector

[0161] 280: Electrode lead

[0162] 282: Positive lead

[0163] 284: Negative lead

[0164] 290: Insulation part

Claims

1. A bag film laminate, comprising: The base material layer, gas barrier layer, and sealant layer are laminated sequentially. The base material layer includes a stretching aid film disposed on the gas barrier layer and a surface protective film disposed on the stretching aid film. The ratio of the tensile strength in the MD direction of the stretching aid film to the tensile strength in the MD direction of the surface protective film is in the range of 0.9 to 1.1, and The ratio of the tensile strength in the TD direction of the stretching auxiliary film to the tensile strength in the TD direction of the surface protective film is in the range of 0.9 to 1.

1.

2. The bag film laminate according to claim 1, wherein, The ratio of the MD-direction elongation of the stretching aid film to the MD-direction elongation of the surface protective film is in the range of 0.9 to 1.1, and The ratio of the elongation in the TD direction of the stretching auxiliary film to the elongation in the TD direction of the surface protective film is in the range of 0.9 to 1.

1.

3. The bag film laminate according to claim 1, wherein, The tensile strength in the MD direction of the surface protective film is in the range of 66 N / 15 mm to 95 N / 15 mm, and The tensile strength in the MD direction of the stretching aid membrane is in the range of 70 N / 15 mm to 90 N / 15 mm.

4. The bag film laminate according to claim 1, wherein, The tensile strength in the TD direction of the surface protective film is in the range of 76 N / 15 mm to 105 N / 15 mm, and The tensile strength in the TD direction of the stretching aid membrane is in the range of 80 N / 15 mm to 100 N / 15 mm.

5. The bag film laminate according to claim 1, wherein, The elongation in the MD direction of the surface protective film is in the range of 105% to 137%, and The elongation in the MD direction of the stretching auxiliary membrane is in the range of 110% to 130%.

6. The bag film laminate according to claim 1, wherein, The elongation in the TD direction of the surface protective film is in the range of 114% to 147%, and The elongation in the TD direction of the stretching auxiliary membrane is in the range of 120% to 140%.

7. The bag film laminate according to claim 1, wherein, The thickness of the surface protective film is 10 μm to 35 μm.

8. The bag film laminate according to claim 1, wherein, The thickness of the stretching auxiliary membrane is 20 μm to 45 μm.

9. The bag film laminate according to claim 1, wherein, The thickness of the base material layer is 40 μm to 70 μm.

10. The bag film laminate according to claim 1, wherein, The thickness of the gas barrier layer is 70 μm to 90 μm.

11. The bag film laminate according to claim 1, wherein, The thickness of the sealant layer is 70 μm to 90 μm.

12. The bag film laminate according to claim 1, wherein, The thickness of the bag film laminate is 100 μm to 300 μm.

13. The bag film laminate according to claim 1, wherein, The ratio of the thickness of the bag film laminate to the thickness of the surface protective film is in the range of 5 to 10.

14. The bag film laminate according to claim 1, wherein, The ratio of the thickness of the gas barrier layer to the thickness of the surface protective film is in the range of 2.5 to 3.

3.

15. The bag film laminate according to claim 1, wherein, The ratio of the thickness of the gas barrier layer to the thickness of the base material layer is in the range of 1.4 to 1.

8.

16. The bag film laminate according to claim 1, wherein, The ratio of the thickness of the stretching auxiliary film to the thickness of the surface protective film is less than or equal to 1.

2.

17. The bag film laminate according to claim 1, wherein, The surface protective film comprises at least one selected from polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyarylate, Teflon, and glass fiber.

18. The bag film laminate according to claim 1, wherein, The stretching-assisted membrane includes at least one selected from nylon 6, nylon 6,6, nylon MXD6 (poly(xylene adipamide)), nylon 4, nylon 4,6 and nylon 4,10.

19. The bag film laminate according to claim 1, wherein, The gas barrier layer comprises at least one selected from aluminum, copper, stainless steel, nickel, titanium, and Invar alloy.

20. The bag film laminate according to claim 1, wherein, The sealant layer comprises at least one selected from polypropylene, polyethylene terephthalate, polyethylene, polycarbonate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyarylate, Teflon, and glass fiber.

21. The bag film laminate according to claim 1, wherein, The sealant layer includes a first sealant layer disposed in contact with the gas barrier layer, a second sealant layer laminated on the first sealant layer, and a third sealant layer laminated on the second sealant layer.

22. A pouch-shaped battery case, said pouch-shaped battery case being prepared by stretching the pouch film laminate according to claim 1.

23. A pouch-type secondary battery, comprising the pouch-type battery case according to claim 22.

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