Pouch film laminate, pouch-type battery case, and pouch-type secondary battery

Abstract

The pouch film laminate according to the present invention includes a base layer, a gas barrier layer, and a sealant layer which are sequentially stacked, wherein the base layer includes an auxiliary stretching film disposed on the gas barrier layer and a surface protection film disposed on the auxiliary stretching film, with the ratio of the auxiliary stretching film to the surface protection film ranging from 0.9 to 1.1 in terms of MD direction tensile strength and from 0.9 to 1.1 in terms of TD direction tensile strength.

Description

Pouch film laminate, pouch-type battery case and pouch-type secondary battery

[0001] Cross-citation with related applications

[0002] This application claims the benefit of 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 entire contents of which are incorporated herein by reference.

[0003]

[0004] Technology field

[0005] The present invention relates to a pouch film laminate, a pouch-shaped battery case, and a secondary battery manufactured by molding the same, and more particularly, to a pouch film laminate, a pouch-shaped battery case, and a secondary battery manufactured by molding the same, which have improved moldability by reducing the difference in mechanical properties between a surface protection film and a stretching auxiliary film.

[0006]

[0007] Secondary batteries are used not only in small products such as digital cameras, P-DVDs, MP3 players, mobile phones, PDAs, portable game devices, power tools, and e-bikes, but also in large products requiring high output such as electric vehicles and hybrid vehicles, as well as in power storage devices that store surplus generated power or renewable energy and power storage devices for backup purposes.

[0008] 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.

[0009] Secondary batteries are classified into pouch type and can type, depending on the material of the case housing the electrode assembly. Pouch type batteries house the electrode assembly in a pouch made of a flexible polymer material. Can type batteries house the electrode assembly in a case made of materials such as metal or plastic.

[0010] A pouch-type battery case is manufactured by forming a cup portion by performing press processing on a flexible pouch film laminate. Then, once the cup portion is formed, an electrode assembly is accommodated in the cup portion's receiving space and a sealing portion is sealed to manufacture a secondary battery.

[0011] 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, each of which has a polymer film, such as polyethylene terephthalate, laminated on one side of a metal gas barrier layer and a sealant layer laminated on the other side.

[0012] Recently, with the increasing demand for high-capacity batteries, such as those for electric vehicles and energy storage systems (ESS), there's a growing need for technologies that increase the amount of cell material per pouch to improve energy density. To compensate for the increased weight and volume of cells, a technology has been developed that increases the thickness of the aluminum gas barrier layer to increase the formability and rigidity of the pouch, the outer material. However, this method has limitations, resulting in a lower overall energy density per volume.

[0013]

[0014] 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 capable of improving formability by changing the properties of a surface protection film included in an outer layer of a pouch structure to be similar to a stretching auxiliary film.

[0015]

[0016] [1] In one aspect, the present invention provides a pouch film laminate comprising a sequentially laminated substrate layer, a gas barrier layer, and a sealant layer, wherein the substrate layer comprises a stretching auxiliary film disposed on the gas barrier layer and a surface protection film disposed on the stretching auxiliary film, wherein a ratio of the MD direction tensile strength of the stretching auxiliary film to the MD direction tensile strength of the surface protection film is 0.9 to 1.1, and a ratio of the TD direction tensile strength of the stretching auxiliary film to the TD direction tensile strength of the surface protection film is 0.9 to 1.1.

[0017] [2] In the pouch film laminate of the above [1], the ratio of the MD direction elongation of the stretching auxiliary film to the MD direction elongation of the surface protection film may be 0.9 to 1.1, and the ratio of the TD direction elongation of the stretching auxiliary film to the TD direction elongation of the surface protection film may be 0.9 to 1.1.

[0018] [3] In the pouch film laminate of [1] and / or [2], the MD direction tensile strength of the surface protection film may be 66 N / 15 mm to 95 N / 15 mm, and the MD direction tensile strength of the stretching auxiliary film may be 70 N / 15 mm to 90 N / 15 mm.

[0019] [4] In at least one of the pouch film laminates among [1] to [3], the surface protection film may have a TD direction tensile strength of 76 N / 15 mm to 105 N / 15 mm, and the stretching auxiliary film may have a TD direction tensile strength of 80 N / 15 mm to 100 N / 15 mm.

[0020] [5] In at least one of the pouch film laminates among [1] to [4], the MD direction elongation of the surface protection film may be 105% to 137%, and the MD direction elongation of the stretching auxiliary film may be 110% to 130%.

[0021] [6] In at least one of the pouch film laminates among [1] to [5], the TD direction elongation of the surface protection film may be 114% to 147%, and the TD direction elongation of the stretching auxiliary film may be 120% to 140%.

[0022] [7] In at least one of the pouch film laminates among [1] to [6], the thickness of the surface protection film may be 10 µm to 35 µm.

[0023] [8] In at least one of the pouch film laminates among [1] to [7], the thickness of the stretching auxiliary film may be 20 µm to 45 µm.

[0024] [9] In at least one of the pouch film laminates among [1] to [8], the thickness of the substrate layer may be 40 µm to 70 µm.

[0025]

[0010] In at least one of the pouch film laminates among [1] to [9], the thickness of the gas barrier layer may be 70 µm to 90 µm.

[0026]

[0011] In at least one pouch film laminate among the above [1] to

[0010] , the thickness of the sealant layer may be 70 ㎛ to 90 ㎛.

[0027]

[0012] In at least one of the pouch film laminates among [1] to

[0011] , the thickness of the pouch film laminate may be 100 µm to 300 µm.

[0028]

[0013] In at least one of the pouch film laminates among [1] to

[0012] , the ratio of the thickness of the pouch film laminate to the thickness of the surface protection film may be 5 to 10.

[0029]

[0014] In at least one of the pouch film laminates among [1] to

[0013] , the ratio of the thickness of the gas barrier layer to the thickness of the surface protection film may be 2.5 to 3.3.

[0030]

[0015] In at least one of the pouch film laminates among [1] to

[0014] , the ratio of the thickness of the gas barrier layer to the thickness of the substrate layer may be 1.4 to 1.8.

[0031]

[0016] In at least one of the pouch film laminates among [1] to

[0015] , the ratio of the thickness of the stretching auxiliary film to the thickness of the surface protection film may be 1.2 or less.

[0032]

[0017] In at least one of the pouch film laminates among the above [1] to

[0016] , the surface protection film may include at least one selected from the group consisting of polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, and Teflon.

[0033]

[0018] In at least one pouch film laminate among the above [1] to

[0017] , the stretching auxiliary film may include at least one selected from the group consisting of nylon 6, nylon 6,6, nylon MXD6 (polyxylylene adipamide), nylon 4, nylon 4,6, and nylon 4,10.

[0034]

[0019] In at least one of the pouch film laminates among [1] to

[0018] , the gas barrier layer may include at least one selected from the group consisting of aluminum, copper, stainless steel, nickel, titanium, and invar.

[0035]

[0020] In at least one pouch film laminate among the above [1] to

[0019] , the sealant layer may include at least one selected from the group consisting of polypropylene, polyethylene terephthalate, polyethylene, polycarbonate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber.

[0036]

[0021] In at least one pouch film laminate among the above [1] to

[0020] , the sealant layer may include a first sealant layer arranged to be 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.

[0037]

[0022] In another aspect, the present invention provides a pouch-shaped battery case manufactured by drawing and molding at least one pouch film laminate among the above [1] to

[0021] .

[0038]

[0023] In another aspect, the present invention provides a pouch-type secondary battery including a pouch-type battery case according to the above

[0022] .

[0039]

[0040] The pouch film laminate according to the present invention is characterized by including a surface protection film having a tensile strength similar to that of the stretching auxiliary film, and when the difference in mechanical properties between the two layers located on the outermost surface of the pouch-type battery case is small, as described above, breakage or pinholes due to the difference in properties of each layer are prevented, significantly improving formability, and thus ensuring sufficient forming depth.

[0041]

[0042] The drawings attached to the specification illustrate preferred embodiments of the present invention and, together with the contents of the invention described above, serve to further understand the technical idea of ​​the present invention. Therefore, the present invention should not be interpreted as being limited to the matters described in such drawings.

[0043] Fig. 1 is a cross-sectional view of a pouch film laminate according to the present invention.

[0044] Figure 2 is an exploded assembly diagram of a pouch-type secondary battery according to the present invention.

[0045]

[0046] 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 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 to explain his or her own invention in the best way.

[0047] The terminology used herein is for the purpose of describing embodiments and is not intended to limit the present invention. In this specification, singular forms also include plural forms, unless specifically stated otherwise. As used herein, the terms "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components in addition to the components mentioned.

[0048] In this specification, MD direction (Machine Direction) means the longitudinal direction of the stretching auxiliary film and surface protection film, and TD direction (Transverse Direction) means the width direction of the stretching auxiliary film and surface protection film.

[0049] The MD tensile strength (N / 15 mm) of the surface protection film and the stretching auxiliary film according to the present invention can be measured as the strength at which a break occurs when the surface protection film and the stretching auxiliary film are cut to have a length (MD direction) x width (TD direction) of 130 mm x 15 mm, respectively, and then fixed to a UTM device with a grip gap of 50 mm and pulled at a tensile speed of 5 mm / min. The MD elongation (%) of the surface protection film and the stretching auxiliary film can be calculated as a value obtained by dividing the grip gap at the time of breakage by the grip gap before stretching (50 mm) and multiplying by 100.

[0050] The tensile strength (N / 15 mm) in the TD direction of the surface protection film and the stretching auxiliary film according to the present invention can be measured by cutting the surface protection film and the stretching auxiliary film to have a length (MD direction) x width (TD direction) of 15 mm x 130 mm, fixing them to a UTM device with a grip gap of 50 mm, and pulling them at a tensile speed of 5 mm / min, and the strength at which a break occurs. The elongation (%) in the TD direction of the surface protection film and the stretching auxiliary film can be calculated by dividing the grip gap at the break by the grip gap before stretching (50 mm) and multiplying the result by 100.

[0051]

[0052] Hereinafter, the present invention will be described in more detail.

[0053] The pouch film laminate according to the present invention comprises at least one of the configurations described below, and may comprise any combination between technically possible configurations among the configurations below.

[0054]

[0055] Pouch film laminate

[0056] First, a pouch film laminate according to the present invention will be described.

[0057] A pouch film laminate (100) according to the present invention includes a sequentially laminated substrate layer (110), a gas barrier layer (120), and a sealant layer (130), and the substrate layer (110) includes a stretching auxiliary film (114) disposed on the gas barrier layer (120) and a surface protection film (112) disposed on the stretching auxiliary film (114).

[0058] Hereinafter, each configuration of the pouch film laminate according to the present invention will be described in more detail with reference to FIG. 1.

[0059]

[0060] (1) Substrate layer

[0061] The substrate layer (110) according to the present invention is formed on the outermost layer of the pouch film laminate (100) to protect the secondary battery from friction and collision with the outside. The substrate layer (110) is made of a polymer and can electrically insulate the electrode assembly from the outside.

[0062] The above-described substrate layer (110) may include a surface protection film (112) and a stretching auxiliary film (114). In this case, the surface protection film (112) may be a layer disposed on the outermost layer of the pouch film laminate, and the stretching auxiliary film (114) may be a layer disposed between the surface protection film (112) and the gas barrier layer (120). The surface protection film (112) and the stretching auxiliary film (114) may each be formed of materials having different materials and / or different physical properties. An interface may exist between the surface protection film (112) and the stretching auxiliary film (114). This means that the surface protection film (112) and the stretching auxiliary film (114) are different layers and may be formed separately.

[0063]

[0064] The surface protection film (112) according to the present invention may be a layer disposed on the outermost layer of the pouch film laminate as described above. In this case, the surface protection film (112) is intended to protect the pouch surface from the external environment and may serve to prevent moisture penetration from the outside, etc.

[0065] The surface protection film (112) may be made of one or more materials selected from the group consisting of polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber. Specifically, the surface protection film (112) may include at least one material selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, which have wear resistance and heat resistance, but is not limited thereto.

[0066] The surface protection film (112) may include additives, if necessary. By including additives in the surface protection film (112), the physical properties of the surface protection film (112) can be changed. For example, as an additive for controlling the tensile strength of the surface protection film (112), at least one of carbon fiber, glass fiber, and aramid fiber may be added.

[0067]

[0068] The thickness of the surface protection film (112) may be 10 µm to 35 µm, preferably 20 µm to 30 µm, more preferably 22 µm to 28 µm, and even more preferably 24 µm to 26 µm. When the thickness of the surface protection film (112) satisfies the above range, it has a similar thickness to the stretching auxiliary film (114) according to the present invention, so that the difference in tensile strength is reduced, and thus the occurrence of breakage due to the difference in physical properties of the two films is prevented, thereby improving the formability of the pouch, and in a structure that requires deep forming by applying pressure, durability is strengthened, so that the problem of the film being torn or wrinkled during forming can be prevented.

[0069]

[0070] The stretching auxiliary film (114) according to the present invention may be a layer disposed between the surface protection film (112) and the gas barrier layer (120) as described above. The stretching auxiliary film (114) has a high elongation, and thus, when deformation is applied, it stretches and does not tear easily, thereby preventing the pouch film laminate from being easily broken during the forming process, thereby assisting in the stretching of the pouch film laminate.

[0071] The stretching auxiliary film (114) may include a polyamide film. The stretching auxiliary film (114) may include at least one selected from the group consisting of nylon 6, nylon 6,6, nylon MXD6 (polyxylylene adipamide), nylon 4, nylon 4,6, and nylon 4,10, but is not limited thereto. Specifically, in order for the stretching auxiliary film (114) to have a melting temperature of 240° C. or higher, the stretching auxiliary film (114) may include nylon 6,6 and / or nylon MXD6.

[0072] The thickness of the stretching auxiliary film (114) may be 20 µm to 45 µm, preferably 20 µm to 30 µm, more preferably 22 µm to 28 µm, and even more preferably 24 µm to 26 µm. When the thickness of the stretching auxiliary film (114) satisfies the above numerical range, the tensile strength is secured while the elongation is increased, thereby achieving a balance with the formability of the gas barrier layer, so that the pouch is not broken during stretching, thereby securing the formability of the pouch, and the reduction in the energy density per volume of the secondary battery due to the thickness of the pouch film laminate becoming excessively thick can be prevented.

[0073]

[0074] The ratio of the thickness of the stretching auxiliary film (114) to the thickness of the surface protection film (112) may be 1.2 or less, preferably 1.2 or less, 1.1 or less, or 1.05 or less, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more, and more preferably 0.9 to 1.05. When the above range is satisfied, the tensile stress is uniformly distributed so that the stress is not concentrated in a specific portion, so that the film is uniformly stretched, and the adhesive force between the two films acts uniformly so that delamination between layers does not occur, thereby improving formability and ensuring a high forming depth.

[0075]

[0076] In the pouch film laminate (100) according to the present invention, the ratio of the MD direction tensile strength of the stretching auxiliary film (114) to the MD direction tensile strength of the surface protection film (112) is 0.9 to 1.1, and the TD direction tensile strength ratio is 0.9 to 1.1. When the MD and TD direction tensile strength ratios of the stretching auxiliary film (114) to the surface protection film (112) satisfy the above ranges, the difference in mechanical properties between the surface protection film (112) and the stretching auxiliary film (114) is reduced, thereby preventing the occurrence of breakage due to the difference in properties during pouch forming, thereby improving the formability of the pouch.

[0077] The MD direction tensile strength ratio of the stretching auxiliary film (114) to the surface protection film (112) may be specifically 0.95 to 1.05, more specifically 0.98 to 1.02, and the TD direction tensile strength ratio of the stretching auxiliary film (114) to the surface protection film (112) may be specifically 0.95 to 1.05, more specifically 0.98 to 1.02.

[0078] In addition, the MD direction elongation ratio of the stretching auxiliary film (114) to the surface protection film (112) may be 0.9 to 1.1, and the TD direction elongation ratio may be 0.9 to 1.1. When the MD and TD direction elongation ratios of the stretching auxiliary film (114) to the surface protection film (112) satisfy the above ranges, the difference in tensile properties between the laminated structural layers is reduced, so that both films are uniformly deformed during drawing molding, and wrinkles due to excessive shrinkage or stretching can be prevented, and stress concentration that may occur at the film interface during molding is reduced, so that layer delamination can be prevented.

[0079] The MD direction elongation ratio of the stretching auxiliary film (114) to the surface protection film (112) may be specifically 0.95 to 1.05, more specifically 0.98 to 1.02, and the TD direction elongation ratio of the stretching auxiliary film (114) to the surface protection film (112) may be specifically 0.95 to 1.05, more specifically 0.98 to 1.02.

[0080]

[0081] The MD direction tensile strength of the surface protection film (112) may be 66 N / 15 mm to 95 N / 15 mm, specifically 70 N / 15 mm to 90 N / 15 mm, more specifically 76 N / 15 mm to 84 N / 15 mm, and the MD direction tensile strength of the stretching auxiliary film (114) may be 70 N / 15 mm to 90 N / 15 mm, specifically 72 N / 15 mm to 88 N / 15 mm, more specifically 75 N / 15 mm to 85 N / 15 mm.

[0082] In addition, the TD direction tensile strength of the surface protection film (112) may be 76 N / 15 mm to 105 N / 15 mm, specifically 81 N / 15 mm to 100 N / 15 mm, more specifically 86 N / 15 mm to 95 N / 15 mm, and the TD direction tensile strength of the stretching auxiliary film (114) may be 80 N / 15 mm to 100 N / 15 mm, specifically 82 N / 15 mm to 98 N / 15 mm, more specifically 85 N / 15 mm to 95 N / 15 mm.

[0083] When the tensile strength in the MD direction or TD direction of the surface protection film (112) and the stretching auxiliary film (114) satisfies the above range, the fatigue and puncture resistance improvement effect after cup forming can be improved, and even if a tensile load of a certain level or higher is applied to the pouch for pouch forming, the problem of the pouch film laminate (100) being broken or pinholes being generated can be prevented.

[0084] The MD direction elongation of the surface protection film (112) may be 105% to 137%, specifically 110% to 130%, more specifically 114% to 126%, and the MD direction elongation of the stretching auxiliary film (114) may be 110% to 130%, specifically 112% to 127%, more specifically 115% to 125%.

[0085] The TD direction elongation of the surface protection film (112) may be 114% to 147%, specifically 120% to 140%, more specifically 124% to 137%, and the TD direction elongation of the stretching auxiliary film (114) may be 120% to 140%, specifically 122% to 138%, more specifically 125% to 135%.

[0086] When the elongation in the MD direction and TD direction of the surface protection film (112) and the stretching auxiliary film (114) satisfies the above range, the gas barrier layer is well held, thereby obtaining an effect of improving formability.

[0087]

[0088] The MD direction and TD direction tensile strength and elongation of the surface protection 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, etc., and thus, the type of film, the thickness of the film, and / or the thickness of the adhesive layer, etc. can be appropriately adjusted to form the surface protection film (112) and the stretching auxiliary film (114) having the desired tensile strength and elongation.

[0089] According to one embodiment, the surface protection film (112) may be a polyethylene terephthalate film, and the stretching auxiliary film (114) may be a nylon film. At this time, it is preferable that the nylon film is disposed on the gas barrier layer (120) side, i.e., on the inside, and the polyethylene terephthalate film is disposed on the surface side of the battery case.

[0090] Polyethylene terephthalate has excellent durability and electrical insulation properties, so when a polyethylene terephthalate film is placed on the surface side, it exhibits excellent durability and insulation properties. However, in the case of the polyethylene terephthalate film, the adhesion with the aluminum alloy thin film constituting the gas barrier layer (120) is weak, and the stretching behavior is also different. Therefore, when the polyethylene terephthalate film is placed on the gas barrier layer (120) side, the substrate layer and the gas barrier layer (120) may be peeled off during the forming process, and the gas barrier layer (120) may not be stretched uniformly, which may cause a problem of reduced formability. In contrast, since the stretching behavior of a nylon film is similar to that of an aluminum alloy thin film constituting the gas barrier layer (120), when a nylon film is placed between the polyethylene terephthalate and the gas barrier layer (120), an effect of improved formability can be obtained.

[0091]

[0092] The above-mentioned base layer (110) may have a composite film structure in which two or more materials are formed in layers. In the composite film structure, an adhesive layer may be additionally formed between each layer. The adhesive layer may be formed by applying an adhesive commonly used in the present invention, for example, a urethane-based adhesive. At this time, the thickness of the adhesive layer may be 1 µm to 8 µm, specifically 1 µm to 5 µm, and more specifically 2 µm to 4 µm. The above-mentioned base layer (110) includes a surface protection film and a stretching auxiliary film, and preferably may further include an adhesive layer disposed between the surface protection film and the stretching auxiliary film. Specifically, the adhesive layer may be formed by applying it between the surface protection film (112) and the stretching auxiliary film (114), and for example, the base layer (110) may have a structure in which a surface protection film / adhesive layer / stretching auxiliary film are sequentially laminated.

[0093] At this time, the thickness of the substrate layer (110) may be 40 ㎛ to 70 ㎛, specifically 45 ㎛ to 60 ㎛, and more specifically 48 ㎛ to 58 ㎛. When the thickness of the substrate layer (110) satisfies the above range, durability, insulation, and formability are excellent. If the thickness of the substrate layer (110) is too thin, durability may be reduced, and the substrate layer may be damaged during the forming process, and if it is too thick, formability may be reduced, and the overall thickness of the pouch film laminate may increase, reducing the battery accommodation space and lowering the energy density. At this time, the thickness of the substrate layer (110) may be a thickness including an adhesive layer that may be included in the substrate layer (110), and may be a thickness including an adhesive layer that bonds the gas barrier layer (120) and the substrate layer (110). As described above, when the thickness of the substrate layer (100) includes the adhesive layer within the substrate layer (100) and the adhesive layer that bonds the gas barrier layer (120) and the substrate layer (110), a more clear effect can be achieved.

[0094]

[0095] (2) Gas barrier layer

[0096] The gas barrier layer (120) according to the present invention is laminated between the substrate layer (110) and the sealant layer (130) 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.

[0097] The gas barrier layer (120) may be formed of a metal. For example, the gas barrier layer may be a metal thin film including one or more metals 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.

[0098] The gas barrier layer (120) may be formed of an aluminum alloy thin film. When the gas barrier layer (120) 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 ensuring complementary electrochemical properties and heat dissipation properties due to the electrode assembly and electrolyte. The aluminum alloy thin film may contain elements other than aluminum (Al). For example, the aluminum alloy thin film may contain one or more selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0099]

[0100] In the past, it was common to form the gas barrier layer (120) to a thickness of 30 ㎛ to 50 ㎛. However, when the thickness of the gas barrier layer is 30 ㎛ to 50 ㎛, even if the pouch film laminate is drawn and formed, there was a limit to deepening the depth of the cup portion or forming the outer wall of the cup portion to be close to vertical, and there was also a limit to reducing the filleting curvature radius of the corner of the cup portion. In addition, there was also a problem that the internal electrode assembly was easily damaged when the battery case was impacted from the outside due to the weak puncture strength.

[0101] Accordingly, in order to improve such problems, the present invention forms the thickness of the gas barrier layer (120) to be 70 ㎛ to 90 ㎛, specifically 75 ㎛ to 85 ㎛, and more specifically 78 ㎛ to 82 ㎛. When the above range is satisfied, the formability of the gas barrier layer is improved, so that the depth of the cup part can be formed deep when drawing-molding the pouch film laminate, and the radius of curvature of the corners of the cup part can also be reduced. Accordingly, the volume of the accommodation space increases, so that more electrodes and separators can be laminated on the electrode assembly accommodated therein, and the energy efficiency per volume can increase. However, when the thickness of the gas barrier layer exceeds 90 ㎛, the thickness of the pouch film laminate becomes excessively thick, which may lower the energy density per volume of the secondary battery.

[0102] The ratio of the thickness of the gas barrier layer to the thickness of the surface protection film may be 2.5 to 3.3. Preferably, it may be 2.50 or more, 2.55 or more, 2.60 or more, 2.65 or more, 2.70 or more, 2.75 or more, 2.80 or more, 2.85 or more, 2.90 or more, 2.95 or more, or 3.00 or more, and 3.30 or less. More preferably, it may be 3.00 to 3.30. When the above range is satisfied, the thickness of the surface protection film and the gas barrier layer are balanced, so that the tensile force is evenly distributed during the molding process, thereby facilitating deformation, and thus ensuring a high molding depth.

[0103]

[0104] The ratio of the thickness of the gas barrier layer to the thickness of the substrate layer may be 1.4 to 1.8, specifically 1.4 to 1.7. When the above range is satisfied, cracking can be prevented during molding, thereby ensuring a high molding depth.

[0105]

[0106] (3) Sealant layer

[0107] The sealant layer (130) according to the present invention is intended to completely seal the interior of the pouch-type battery case by mutually thermally bonding the sealing portion when the pouch-type battery case containing the electrode assembly inside is sealed. To this end, the sealant layer (130) may be formed of a material having excellent thermal bonding strength.

[0108] The sealant layer (130) may be formed of a material having insulating, corrosion-resistant, and sealing properties. Specifically, since the sealant layer (130) is in direct contact with the electrode assembly and / or electrolyte inside the pouch-type battery case, it may be formed of a material having insulating and corrosion-resistant properties. In addition, since the sealant layer (130) must completely seal the inside of the pouch-type 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 (130) may be formed of a polymer material.

[0109] The sealant layer (130) may include at least one selected from the group consisting of polypropylene, polyethylene terephthalate, polyethylene, polycarbonate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber, and preferably may include a polyolefin resin such as polypropylene and / or polyethylene. In this case, the polypropylene may be composed of cast polypropylene (CPP), acid modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene terpolymer.

[0110] The thickness of the sealant layer (130) may be 70 µm to 90 µm, specifically 75 µm to 85 µm, and more specifically 78 µm to 82 µm. 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.

[0111]

[0112] The above sealant layer (130) may include a first sealant layer arranged to be 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.

[0113]

[0114] According to one embodiment of the present invention, the first sealant layer may include polypropylene, and preferably, to secure long-term adhesion between the gas barrier layer and the first sealant layer, may include acid-modified polypropylene (PPa). Here, the acid-modified polypropylene may be maleic anhydride polypropylene (MAH PP).

[0115]

[0116] According to one embodiment of the present invention, the second sealant layer may be formed of a material having insulating, corrosion-resistant, and sealing properties. Preferably, it may be formed of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber. Preferably, the second sealant layer may be formed of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may be composed of non-stretched polypropylene, acid-modified polypropylene, polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene terpolymer. Here, the acid-modified polypropylene may be maleic anhydride polypropylene (MAH PP). More preferably, the second sealant layer may include cast polypropylene (CPP) having heat sealability and high tensile strength.

[0117]

[0118] According to one embodiment of the present invention, the third sealant layer may include polypropylene, preferably a polypropylene random copolymer, more preferably at least one selected from the group consisting of an ethylene-propylene random copolymer and a butene-propylene random copolymer, and even more preferably an ethylene-propylene random copolymer. When the above conditions are satisfied, the melt flow rate (MFR) is high and the melting point is low, so that when the same amount of heat is applied, the desired sealing thickness can be quickly achieved. Accordingly, even without increasing the sealing temperature, the sealing time can be shortened compared to when a polypropylene homocopolymer is included, and the process time of the secondary battery can be shortened, thereby improving productivity and processability, and at the same time having strong thermal bonding strength, so that the pouch-type battery case can have excellent sealing properties.

[0119]

[0120] The pouch film laminate according to the present invention as described above can be manufactured through a manufacturing method of 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 substrate 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) through co-extrusion or an adhesive layer, but is not limited thereto.

[0121] The pouch film laminate may have a total thickness of 100 µm to 300 µm, specifically 160 µm to 250 µm, and more specifically 200 µm to 230 µm. When the thickness of the pouch film laminate satisfies the above range, the forming depth can be increased while minimizing a decrease in battery accommodation space and a decrease in sealing durability due to an increase in the thickness of the pouch laminate.

[0122]

[0123] The ratio of the thickness of the pouch film laminate to the thickness of the surface protection film may be 5 to 10, preferably 6.0 or more, 6.5 or more, 7.5 or more, or 8.0 or more, and 10 or less, 9.5 or less, or 9.0 or less, and more preferably 8.0 to 9.0. When the above range is satisfied, the ratio of the thickness of the surface protection film to the thickness of the pouch film laminate is appropriate, so that tensile deformation does not easily occur, and thus the phenomenon of wrinkles occurring during the molding process can be prevented, and thus the molding depth can be increased, and the robustness can be excellent. In addition, when the above condition is satisfied, the edge and / or corner are the parts where the stretching stress is concentrated during pouch molding, and since the stretching occurs the most, they are formed thinner than other parts and are vulnerable to external impact, and therefore the thickness of the edge and / or corner is prevented from becoming excessively thin, and the robustness can be excellent.

[0124]

[0125] Pouch-type secondary battery

[0126] Next, the pouch-type secondary battery according to the present invention will be described in more detail with reference to FIG. 2.

[0127] A pouch-type secondary battery (200) according to the present invention includes a pouch-type battery case (210) in which an electrode assembly is accommodated, the pouch-type battery case (210) includes a pouch film laminate (100), the pouch film laminate (100) includes a substrate layer (110), a gas barrier layer (120), and a sealant layer (130) that are sequentially laminated, the substrate layer includes a surface protection film (112) and a stretching auxiliary film (114), and the stretching auxiliary film (114) is disposed between the surface protection film (112) and the gas barrier layer (120).

[0128]

[0129] (1) Pouch-type battery case

[0130] The pouch-shaped battery case (210) according to the present invention can house an electrode assembly (260) inside. The pouch-shaped battery case (210) can be manufactured by molding the pouch film laminate of the present invention described above. Since the detailed configuration and physical properties of the pouch film laminate are the same as those described above, a detailed description thereof will be omitted.

[0131] The pouch film laminate can 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) can include a cup portion (222) and a receiving portion (224). The receiving portion (224) is a place for receiving an electrode assembly, and can mean a receiving space formed in the shape of a pocket on the inside of the cup portion (222) as the cup portion (222) is formed.

[0132]

[0133] According to one embodiment of the present invention, a 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 and separated from each other.

[0134] According to another embodiment of the present invention, when forming a cup portion on a pouch film laminate, two symmetrical cup portions (222, 232) can be drawn and formed adjacent to each other on one pouch film laminate. In this case, cup portions (222, 232) can be formed in the first case (220) and the second case (230), respectively, 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 portions (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 portion (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.

[0135]

[0136] The pouch-type battery case (210) can 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. Specifically, 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) can be housed in a receiving portion (224) provided in a cup portion (222) of the first case (220), and the second case (230) can cover the receiving portion (224) from above. Subsequently, an electrolyte can be injected into the interior of the receiving portion (224), and the sealing portions (250) formed on the edges of the first case (220) and the second case (230) can be sealed.

[0137] The sealing portion (250) can perform a function of sealing the receiving portion (224). Specifically, the sealing portion (250) can seal the receiving portion (224) while being formed along the edge of the receiving portion (224). The temperature at which the sealing portion (250) is sealed can be 180°C to 250°C, specifically 200°C to 250°C, and more specifically 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 through thermal bonding.

[0138]

[0139] (2) Electrode assembly

[0140] The electrode assembly (260) according to the present invention can be inserted into a pouch-type battery case (210) and sealed by the pouch-type battery case (210) after electrolyte injection.

[0141] The electrode assembly (260) may be formed by sequentially stacking an anode, a separator, and a cathode. Specifically, 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.

[0142] 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 is typically formed by stirring granular active materials, auxiliary conductors, binders, and conductive agents with the addition of a solvent. The solvent can be removed in a subsequent process.

[0143] A slurry containing an electrode active material, 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 these are laminated on both sides of a separator, thereby manufacturing an electrode assembly (260) in a predetermined shape. The types of electrode assembly (260) may include, but are not limited to, a stack type, a jelly roll type, a stack and folding type, etc.

[0144] The electrode assembly (260) may include an electrode tab (270).

[0145] The electrode tabs (270) are respectively connected to the positive and negative electrodes of the electrode assembly (260), and may protrude outward from the electrode assembly (260) to serve as a path for electrons to 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. 1, the electrode tabs (270) may protrude in different directions of the electrode assembly (260), but are not limited thereto, and may be formed to protrude in various directions, such as protruding in parallel in the same direction from one side.

[0146]

[0147] (3) Electrode lead

[0148] The electrode lead (280) according to the present invention 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 or the like.

[0149] 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). Specifically, 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).

[0150] 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 nickel (Ni)-coated copper material. A portion of the electrode lead (280) protruding outside the battery case (210) may serve as a terminal portion and be electrically connected to an external terminal.

[0151]

[0152] (4) Insulation

[0153] The insulating portion (290) according to the present invention 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) may be formed of a non-conductive material that does not conduct electricity well. Generally, the insulating portion (290) is often formed 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) may be used.

[0154] The insulating portion (290) may be arranged to surround the outer circumference 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 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 thermally fused, and may adhere the electrode lead (280) to the battery case (210).

[0155]

[0156] (5) Electrolyte

[0157] The pouch-type secondary battery (200) according to the present invention may further include an electrolyte (not shown) injected into the pouch-type battery case (210). The electrolyte according to the present invention 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, oxide-type, or polymer-type, and such a solid electrolyte may have flexibility that is easily deformed by an external force.

[0158] Meanwhile, if pressure is applied due to external force or gas generation, peeling may occur at an interface with relatively weak adhesive strength among the sealed battery cases (210). For example, peeling may occur along the interface between sealant layers that are thermally bonded to each other. However, in the case of the battery case manufactured from the pouch film laminate of the present invention, since thermal bonding between the sealant layers with improved flow characteristics upon melting is smoothly achieved, the adhesive strength at the interface is maintained high, thereby achieving excellent sealing strength.

[0159]

[0160] Hereinafter, the present invention will be described in more detail through specific examples. However, the following examples are merely illustrative and serve to aid understanding of the present invention and do not limit its scope. It will be apparent to those skilled in the art that various modifications and variations are possible within the scope and technical spirit of this disclosure, and such modifications and variations are naturally within the scope of the appended claims.

[0161]

[0162] Example 1

[0163] A urethane adhesive was applied 3 ㎛ thick between a 25 ㎛ thick nylon film and a 25 ㎛ thick polyethylene terephthalate film to form a first adhesive layer 3 ㎛ thick, and then thermally laminated to form a substrate layer. At this time, films having the tensile strength and elongation as described in Tables 1 and 2 below were used as the nylon film and polyethylene terephthalate film.

[0164] After that, a urethane adhesive was applied to one side of an aluminum alloy having a thickness of 80 ㎛ as a gas barrier layer to form a second adhesive layer having a thickness of 3 ㎛, and the base layer manufactured above was laminated on the second adhesive layer, followed by thermal lamination.

[0165] Next, a pouch film laminate was manufactured by sequentially laminating a surface protection film / first adhesive layer / elastic auxiliary film / second adhesive layer / gas barrier layer / first sealant layer / second sealant layer / third sealant layer by coextruding a first sealant layer having a thickness of 30 μm containing acid modified polypropylene (PP) on the other surface of the gas barrier layer, a second sealant layer having a thickness of 30 μm containing non-stretched polypropylene (PP), and a third sealant layer having a thickness of 20 μm containing an ethylene-propylene random copolymer.

[0166]

[0167] Examples 2 to 4 and Comparative Examples 1 to 3

[0168] Pouch film laminates of Examples 2 to 4 and Comparative Examples 1 to 3 were manufactured in the same manner as in Example 1, except that films having tensile strength and elongation in the MD and TD directions as shown in Tables 1 and 2 below were used as nylon films and polyethylene terephthalate films, respectively.

[0169]

[0170] Comparative Example 4

[0171] A pouch film laminate was manufactured in the same manner as in Example 1, except that the thickness of the surface protection film was 12 μm and the thickness of the gas barrier layer was 60 μm.

[0172]

[0173] Comparative Example 5

[0174] A pouch film laminate was manufactured in the same manner as Example 1, except that the thickness of the surface protection film was 12 μm, the thickness of the stretching auxiliary film was 15 μm, the thicknesses of the gas barrier layer, the first sealant layer, and the third sealant layer were 40 μm, and the second sealant layer was not included, thereby manufacturing a pouch film laminate in which the surface protection film / first adhesive layer / stretching auxiliary film / second adhesive layer / gas barrier layer / first sealant layer / third sealant layer were sequentially laminated.

[0175]

[0176] MD direction tensile strength [N / 15mm] Tensile strength Non-TD direction tensile strength [N / 15mm] Tensile strength Non-nylon film PET film Nylon film PET film Example 182781.0593891.04 Example 276800.9582840.98 Example 388831.0495901.05 Example 490950.95991040.95 Comparative example 175890.8487851.02 Comparative example 283811.0292721.27 Comparative example 3821000.82901060.85 Comparative example 468461.4779401.97 Comparative example 582441.8693372.51

[0177] MD direction elongation [%] elongation Non-TD direction elongation [%] elongation Non-nylon film PET film Nylon film PET film Example 1 20 1 1 4 1.05 13 1 1 2 6 1.04 Example 2 1 1 2 1 1 6 0.96 12 5 12 9 0.97 Example 3 1 2 8 12 2 1.05 13 3 12 9 1.03 Example 4 1 3 0 1 2 5 1.04 13 8 14 2 0.97 Comparative example 1 1 2 0 1 3 6 0.88 12 5 12 8 0.98 Comparative example 2 1 2 5 1 1 7 1.05 13 6 11 4 1.19 Comparative example 3 1 0 2 1 3 8 0.74 9 9 12 6 0.79 Comparative example 4 1 1 2 7 0 1.60 10 16 9 1.46 Comparative example 5130771.68124641.93

[0178] Experimental Example: Evaluation of Maximum Forming Depth

[0179] The maximum forming depth of the pouch film laminates manufactured in Examples 1 to 4 and Comparative Examples 1 to 5 was measured.

[0180] Specifically, when a pouch film laminate was cut to 266 mm wide and 200 mm long and then cold-formed to form a cup portion of 90 mm wide and 160 mm long, the processing depth just before the pouch film laminate was broken was defined as the maximum processing depth (unit: mm). 15 pouch film laminates of Examples 1 to 4 and Comparative Examples 1 to 5 were prepared, and the above maximum processing depth measurement experiment was performed 15 times, and the average value thereof is shown in Table 3 below.

[0181]

[0182] Average value of maximum processing depth [mm] Example 113.5 Example 213.0 Example 313.0 Example 413.0 Comparative Example 112.5 Comparative Example 213.0 Comparative Example 311.0 Comparative Example 47.5 Comparative Example 59.0

[0183] According to Table 3 above, in Examples 1 to 4, where the ratio of the MD direction tensile strength and the TD direction tensile strength of the nylon film to the PET film is 0.9 to 1.1, the processing depth is greater than that of Comparative Examples 1 to 5, and it can be confirmed from this that the formability of the pouch film laminate manufactured in Examples 1 to 4 is superior to that of Comparative Examples 1 to 5.

[0184]

[0185] [Explanation of symbols]

[0186] 100: Pouch film laminate

[0187] 110: Base layer

[0188] 112: Surface protection film

[0189] 114: Extension auxiliary film

[0190] 120: Gas barrier layer

[0191] 130: Sealant layer

[0192] 200: Pouch-type secondary battery

[0193] 210: Pouch-type case

[0194] 220: Case 1

[0195] 222: Cup Department

[0196] 224: Reception area

[0197] 230: Case 2

[0198] 232: Cup

[0199] 240: Bridge section

[0200] 250: Sealing part

[0201] 260: Electrode assembly

[0202] 270: Electrode tab

[0203] 271: Negative tab

[0204] 272: Positive tab

[0205] 280: Electrode lead

[0206] 282: Positive lead

[0207] 284: Negative lead

[0208] 290: Insulation

Claims

1. Contains a sequentially laminated substrate layer, a gas barrier layer, and a sealant layer, The above-mentioned substrate layer includes a stretching auxiliary film disposed on the gas barrier layer and a surface protection film disposed on the stretching auxiliary film, The ratio of the MD direction tensile strength of the stretching auxiliary film to the MD direction tensile strength of the surface protection film is 0.9 to 1.1, A pouch film laminate having a ratio of the TD direction tensile strength of the stretching auxiliary film to the TD direction tensile strength of the surface protection film of 0.9 to 1.

1.

2. In claim 1, The ratio of the MD direction elongation of the stretching auxiliary film to the MD direction elongation of the surface protection film is 0.9 to 1.1, A pouch film laminate having a ratio of the TD direction elongation of the stretching auxiliary film to the TD direction elongation of the surface protection film of 0.9 to 1.

1.

3. In claim 1, The MD direction tensile strength of the above surface protection film is 66 N / 15 mm to 95 N / 15 mm, A pouch film laminate having a tensile strength in the MD direction of the above-mentioned stretching auxiliary film of 70 N / 15 mm to 90 N / 15 mm.

4. In claim 1, The tensile strength of the surface protection film in the TD direction is 76 N / 15 mm to 105 N / 15 mm, A pouch film laminate having a tensile strength in the TD direction of the above-mentioned extension auxiliary film of 80 N / 15 mm to 100 N / 15 mm.

5. In claim 1, The MD direction elongation of the above surface protection film is 105% to 137%, A pouch film laminate having an MD direction elongation ratio of the above-mentioned stretching auxiliary film of 110% to 130%.

6. In claim 1, The TD direction elongation of the above surface protection film is 114% to 147%, A pouch film laminate having a TD direction elongation ratio of the above-mentioned elongation auxiliary film of 120% to 140%.

7. In claim 1, A pouch film laminate having a thickness of the surface protection film of 10㎛ to 35㎛.

8. In claim 1, A pouch film laminate having a thickness of the above-mentioned extension auxiliary film of 20㎛ to 45㎛.

9. In claim 1, A pouch film laminate having a thickness of the above-mentioned substrate layer of 40 ㎛ to 70 ㎛.

10. In claim 1, A pouch film laminate having a thickness of the gas barrier layer of 70 ㎛ to 90 ㎛.

11. In claim 1, A pouch film laminate having a thickness of the sealant layer of 70 ㎛ to 90 ㎛.

12. In claim 1, A pouch film laminate having a thickness of 100 ㎛ to 300 ㎛.

13. In claim 1, A pouch film laminate having a ratio of the thickness of the pouch film laminate to the thickness of the surface protection film of 5 to 10.

14. In claim 1, A pouch film laminate having a ratio of the thickness of the gas barrier layer to the thickness of the surface protection film of 2.5 to 3.

3.

15. In claim 1, A pouch film laminate in which the ratio of the thickness of the gas barrier layer to the thickness of the substrate layer is 1.4 to 1.

8.

16. In claim 1, A pouch film laminate in which the ratio of the thickness of the stretching auxiliary film to the thickness of the surface protection film is 1.2 or less.

17. In claim 1, The above surface protection film is a pouch film laminate comprising at least one selected from the group consisting of polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber.

18. In claim 1, The above-mentioned stretching auxiliary film is a pouch film laminate comprising at least one selected from the group consisting of nylon 6, nylon 6,6, nylon MXD6 (polyxylylene adipamide), nylon 4, nylon 4,6, and nylon 4,10.

19. In claim 1, A pouch film laminate in which the gas barrier layer comprises at least one selected from the group consisting of aluminum, copper, stainless steel, nickel, titanium, and invar.

20. In claim 1, A pouch film laminate, wherein the sealant layer comprises at least one selected from the group consisting of polypropylene, polyethylene terephthalate, polyethylene, polycarbonate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber.

21. In claim 1, A pouch film laminate comprising a first sealant layer arranged to be 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 manufactured by drawing and molding the pouch film laminate of claim 1.

23. A pouch-type secondary battery comprising the pouch-type battery case of claim 22.

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