Adhesive film for secondary battery and lithium secondary battery comprising same

Abstract

The present invention relates to an adhesive film for a secondary battery, the adhesive film comprising: an outer insulating layer; and an adhesive layer positioned on one surface of the outer insulating layer, wherein the contact angle of the adhesive layer is 100° or more, and the wetting tension of the adhesive layer is less than 30 mN / m.

Description

Adhesive film for secondary battery and lithium secondary battery comprising the same Cross-citation with related applications This application claims the benefit of priority from Korean Patent Application No. 10-2023-0190231, filed December 22, 2023, the entire contents of which are incorporated herein by reference. Technical field The present invention relates to an adhesive film for a secondary battery and a lithium secondary battery comprising the same, and more specifically, to an adhesive film for a secondary battery having excellent electrolyte resistance and a lithium secondary battery comprising the same. In general, types of secondary batteries include nickel cadmium batteries, nickel hydrogen batteries, lithium ion batteries, and lithium ion polymer batteries. These secondary batteries are used in not only small products such as digital cameras, P-DVDs, MP3Ps, mobile phones, PDAs, portable game devices, power tools, and e-bikes, but also large products requiring high output such as electric vehicles or hybrid vehicles, as well as power storage devices that store surplus generated power or renewable energy and backup power storage devices. However, concerns about the safety of lithium secondary batteries are growing due to recent occurrences of fires and explosions involving lithium secondary batteries. In particular, as the usage environments of lithium secondary batteries become more diverse and extreme, securing the safety of lithium secondary batteries in high-temperature environments is emerging as an important issue. Lithium secondary batteries are manufactured by manufacturing an electrode assembly including a positive electrode, a negative electrode, and a separator, then housing the electrode assembly in a battery case, injecting an electrolyte, and sealing the battery. At this time, an adhesive film is used for purposes such as fixing the electrode assembly housed in the battery case, protecting the welding area between the electrode tabs and the electrode leads that extend and protrude from each electrode plate of the electrode assembly, or fixing the side folding of the sealed secondary battery. However, if a lithium secondary battery with an adhesive film attached is continuously exposed to a high temperature environment, the adhesive strength of the adhesive film in contact with the electrolyte may decrease or the appearance of the adhesive film may change. Accordingly, the sealing property of the battery case may decrease or the quality may deteriorate due to the appearance change, and this may act as one of the factors that reduces the high temperature safety of the lithium secondary battery. The present invention is intended to solve the above problems, and to provide an adhesive film for a secondary battery having improved electrolyte resistance, excellent adhesiveness even after electrolyte impregnation, and suppression of appearance deformation, and a lithium secondary battery including the same having excellent high-temperature safety. [1] The present invention provides an adhesive film for a secondary battery, comprising: an outer insulating layer; and an adhesive layer positioned on one surface of the outer insulating layer; wherein a contact angle of the adhesive layer is 100° or more and a wetting tension of the adhesive layer is less than 30 mN / m. [2] The present invention provides an adhesive film for a secondary battery, wherein the adhesive layer comprises a rubber-based resin in the above [1]. [3] The present invention provides an adhesive film for a secondary battery, wherein, in the above [1] or [2], the rubber-based resin is at least one selected from the group consisting of natural rubber, epoxidized natural rubber, polyisobutylene rubber, epoxidized styrene block copolymer, ethylene propylene diene monomer rubber, and styrene-ethylene-butylene-styrene copolymer. [4] The present invention provides an adhesive film for a secondary battery, wherein in at least one of the above [1] to [3], the outer insulating layer is at least one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyimide, non-stretched polypropylene, high-density polyethylene, and low-density polyethylene. [5] The present invention provides an adhesive film for a secondary battery, wherein the adhesive layer has an adhesive strength of 200 gf / 25 mm or more in at least one of the above [1] to [4]. [6] The present invention provides an adhesive film for a secondary battery, wherein in at least one of the above [1] to [5], the adhesive layer has an internal electrolyte adhesive strength of 100 gf / 25 mm or more. [7] The present invention provides an adhesive film for a secondary battery, wherein in at least one of the above [1] to [6], the adhesive layer has an internal electrolyte index of 3 or less, as defined by the following equation 1. [Formula 1] [8] The present invention provides a lithium secondary battery comprising: an electrode assembly including a positive electrode, a negative electrode, and a separator; an electrode tab extending and protruding from each electrode plate of the electrode assembly; an electrode lead connected to the electrode tab by welding; an adhesive film for a secondary battery according to any one of [1] to [7]; an electrolyte; and a battery case in which the electrode assembly and the electrolyte are accommodated. [9] The present invention provides a lithium secondary battery, wherein, in the above [8], the adhesive film for the secondary battery is positioned on a welding portion where the electrode lead and the electrode tab are connected.

[0010] The present invention provides a lithium secondary battery, wherein, in the above [8], the adhesive film is positioned on the outer peripheral surface of the electrode assembly.

[0011] The present invention provides a lithium secondary battery, wherein, in the above [8], the adhesive film is positioned on a folded area of ​​the sealing portion of the battery case.

[0012] The present invention provides a lithium secondary battery, wherein, in at least one of the above [8] to

[0011] , the battery case is a pouch-type battery case. The adhesive film for a secondary battery according to the present invention includes an adhesive layer having a contact angle of 100° or more and a wetting tension of less than 30 mN / m, so that the adhesive film has excellent electrolyte resistance, so that a swelling phenomenon does not occur even when in contact with an electrolyte, and a decrease in adhesive strength can be suppressed, and accordingly, when applied to a lithium secondary battery, the adhesive film can be prevented from being detached, thereby improving safety and improving poor appearance of the lithium secondary battery. In particular, a lithium secondary battery including the same can have improved safety in a high-temperature environment. Figure 1 is a cross-sectional view showing the laminated state of an adhesive film according to one embodiment of the present invention. FIG. 2 is an exploded assembly drawing of a lithium secondary battery that does not illustrate an adhesive film for a secondary battery according to the present invention. Figure 3 is an exploded assembly diagram showing a lithium secondary battery according to one embodiment of the present invention. Figure 4 is an exploded assembly diagram showing a lithium secondary battery according to another embodiment of the present invention. Hereinafter, the present invention will be described in more detail. The terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as having meanings and concepts consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to explain his or her own invention in the best manner. The terminology used in this specification is for the purpose of describing exemplary embodiments only and is not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, it should be understood that the terms “include,” “comprising,” or “having” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof. In the present invention, the “contact angle” means, when a water drop is dropped on the adhesive layer of the adhesive film according to the present invention in the air, the angle formed by the tangent line and the surface of the adhesive layer at the point where the air, the water drop and the adhesive layer come into contact, of the angles that include the water droplet, and specifically, it can mean the angle formed by the interface of the adhesive layer surface and the water droplet measured within 5 seconds after dropping one drop of distilled water on the adhesive layer of the adhesive film according to the present invention at room temperature (25°C) using Phoenix mt of SEO Co. In the present invention, “adhesive strength” means the adhesive strength when the surface opposite to the surface of the adhesive layer in contact with the outer insulating layer is pressed against a SUS304 substrate using a 2 kg roller, and then the adhesive film is peeled at a peeling speed of 300 mm / min and a peeling angle of 180° at 25°C. In the present invention, “wetting tension” means the maximum surface tension of a liquid that spreads without bunching up on the surface of an adhesive layer, and has a unit of mN / m. The wetting tension can be measured according to a method compliant with JIS K 6768:1999, and specifically, after applying a solution to the surface of the adhesive layer, the state in which the solution spreads or forms beads on the surface is observed, and the highest surface tension value at which the solution spreads uniformly on the surface of the adhesive layer for 2 seconds or longer can be measured as the wetting tension of the adhesive layer using a Phoenix mt device of SEO Corporation. In the present invention, the “electrolyte adhesion” means the adhesion of an adhesive layer measured after immersing the adhesive film according to the present invention in an electrolyte, and specifically, an adhesive film cut to a size of 25 mm x 150 mm is immersed in an electrolyte, stored at 60°C for 24 hours, the impregnated adhesive film is taken out, and the opposite side of the adhesive layer in contact with the outer insulating layer is pressed against a SUS304 substrate using a 2 kg roller, and then the adhesive film is peeled at 25°C at a peeling speed of 300 mm / min and a peeling angle of 180°. The adhesion of the adhesive film at this time can be measured using ASTM D 3330. The adhesive film for a secondary battery and the lithium secondary battery according to the present invention include at least one of the configurations disclosed below, and may include any combination between technically possible configurations among the configurations below. Hereinafter, the present invention will be described in more detail. Adhesive film for secondary batteries An adhesive film for a secondary battery according to the present invention comprises an outer insulating layer; and an adhesive layer positioned on one surface of the outer insulating layer; wherein a contact angle of the adhesive layer is 100° or more, and a wetting tension of the adhesive layer is less than 30 mN / m. Figure 1 is a cross-sectional view showing the laminated state of an adhesive film according to one embodiment of the present invention. Referring to FIG. 1, an adhesive film (10) according to one embodiment of the present invention includes an outer insulating layer (11) and an adhesive layer (12) positioned on a first surface of the outer insulating layer. The shape of the adhesive film may vary without limitation depending on the intended use. For example, the adhesive film used to fix the shape of the electrode assembly may be in the shape of a rectangular plate, but is not limited thereto and may be used in various shapes such as a circular, triangular, or amorphous plate shape. Next, the outer insulating layer and adhesive layer constituting the adhesive film of the present invention will be described in more detail. (1) Outer insulation layer The external insulating layer according to the present invention can serve to provide mechanical rigidity necessary for performing a process of attaching an adhesive film to a secondary battery and implementing adhesive strength of the adhesive film, and can serve to protect the adhesive layer. At this time, the external insulating layer is a film or sheet-shaped layer and can have a shape such as a circle, a triangle, or an amorphous shape in addition to a square shape. Accordingly, the outer insulating layer may be used without particular limitation as long as it can provide mechanical rigidity to the adhesive film and protect the adhesive layer. For example, the outer insulating layer may include at least one selected from the group consisting of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), cast polypropylene (CPP), high density polyethylene (HDPE), and low density polyethylene (LDPE). Specifically, when the adhesive film is positioned on the welding portion where the electrode lead and the electrode tab of the secondary battery are connected, the outer insulating layer may preferably include non-stretched polypropylene. In this case, even if the outer insulating layer of the adhesive film is mixed and sealed during the process of sealing the pouch of the pouch-type secondary battery, the problems of reduced sealing strength and reduced insulation may be reduced because the outer insulating layer and the sealant layer of the pouch have similar components. Alternatively, when the adhesive film is positioned on the outer surface of the electrode assembly or the folded area of ​​the sealing portion of the battery case, the outer insulating layer may preferably include polyethylene terephthalate. In this case, since the mechanical rigidity and chemical resistance of the outer insulating layer are excellent, the electrode assembly or the folded area of ​​the sealing portion can be sufficiently fixed by the adhesive film. However, the components of the outer insulation layer are not limited thereto. Meanwhile, the thickness of the outer insulating layer may be 10 ㎛ to 110 ㎛, preferably 15 ㎛ to 105 ㎛, and more preferably 17 ㎛ to 100 ㎛. When the above range is satisfied, the tensile strength of the outer insulating layer is sufficiently secured, so that the adhesive film does not break easily during the roll process of attaching the adhesive film to the secondary battery, and the attachment process can be facilitated. Alternatively, when the adhesive film is positioned on the welding portion where the electrode lead and the electrode tab of the secondary battery are connected according to one embodiment of the present invention, the thickness of the outer insulating layer may be 30 µm to 110 µm, preferably 45 µm to 110 µm, and more preferably 60 µm to 100 µm. When the above range is satisfied, the adhesive film can sufficiently cover the bead generated at the welding portion, thereby preventing the sealant layer of the pouch film from being damaged by the bead. According to another embodiment of the present invention, when the adhesive film is positioned on the outer peripheral surface of the electrode assembly of the secondary battery, the thickness of the outer insulating layer may be 10 µm to 50 µm, preferably 12 µm to 40 µm, and more preferably 15 µm to 30 µm. When the above range is satisfied, the adhesive film can firmly fix the electrode assembly to prevent short-circuiting between the positive and negative electrodes, and can prevent damage to the electrode assembly due to collision occurring during the process. According to another embodiment of the present invention, when the adhesive film is positioned on the folded area of ​​the sealing portion of the battery case of the secondary battery, the thickness of the outer insulating layer may be 10 ㎛ to 50 ㎛, preferably 12 ㎛ to 40 ㎛, and more preferably 15 ㎛ to 30 ㎛. When the above range is satisfied, the energy density of the secondary battery and the vent pressure of the sealing portion can be improved by firmly fixing the sealing portion so that it is folded. (2) Adhesive layer The adhesive layer according to the present invention may be a layer that serves to attach the adhesive film to an adherend. The adhesive layer is located on one side of the outer insulating layer. Specifically, the adhesive layer may be located on at least one side of both sides of the outer insulating layer. In addition, the adhesive layer may have a single-layer or multi-layer structure. The adhesive layer has a contact angle of 100° or more. Specifically, the adhesive layer may have a contact angle of 100° or more, 105° or more, 110° or more, 115° or more, 120° or more, and may have a contact angle of 150° or less, 145° or less, 140° or less, 135° or less, 130° or less, 125° or less, or 120° or less. For example, the adhesive layer may have a contact angle of 100° or more, preferably 100° to 150°, more preferably 105° to 140°, and even more preferably 115° to 125°. When the above contact angle satisfies the above range, the adhesive layer can have sufficient hydrophobic properties, so that the electrolyte can be prevented from penetrating into the adhesive layer even when in contact with the electrolyte, and accordingly, the phenomenon of the adhesive layer swelling due to the electrolyte can be suppressed, the adhesive strength of the adhesive layer can be prevented from decreasing, and it can contribute to the safety and appearance improvement of the battery under high temperature conditions. The above contact angle can be appropriately controlled by the type of adhesive included in the adhesive layer, the type and content of additives, surface treatment such as plasma treatment, or the surface roughness of the adhesive layer. The wetting tension of the above adhesive layer is less than 30 mN / m. Specifically, the wetting tension of the adhesive layer is less than 30 mN / m, 29.5 mN / m or less, 29 mN / m or less, 28.5 mN / m or less, 28 mN / m or less, 27.5 mN / m or less, 27 mN / m or less, 1 mN / m or more, 2 mN / m or more, 3 mN / m or more, 4 mN / m or more, 5 mN / m or more, 6 mN / m or more, 7 mN / m or more, 8 mN / m or more, 9 mN / m or more, 10 mN / m or more, 11 mN / m or more, 12 mN / m or more, 13 mN / m or more, 14 mN / m or more, 15 mN / m or more, 16 mN / m or more, 17 mN / m or more, 18 mN / m or more, 19 mN / m or more, or It can be 20 mN / m or more. For example, the wetting tension of the adhesive layer can be less than 30 mN / m, 1 mN / m or more and less than 30 mN / m, 5 mN / m to 29 mN / m, 10 mN / m to 28 mN / m, or 20 mN / m to 27 mN / m. When the above range is satisfied, the wettability of the adhesive layer is low, so that it may be difficult for the electrolyte to spread or penetrate the surface, and accordingly, the chemical reaction between the adhesive layer and the electrolyte may be suppressed, and deterioration of the adhesive layer or deterioration of performance due to electrolyte decomposition may be prevented. Therefore, even if it comes into contact with the electrolyte, the structural stability of the adhesive layer may be excellent, so that the electrolyte resistance may be improved, and accordingly, the adhesive strength and appearance of the adhesive layer may be maintained even in a high-temperature situation. According to the present invention, when the contact angle of the adhesive layer is 100° or more and the wetting tension is less than 30 mN / m, the adhesive layer can have sufficient electrolyte resistance, and thus the adhesive film can be prevented from being detached or its appearance from being deformed even in high temperature or high voltage situations. The above wetting tension can be appropriately adjusted by the type of adhesive included in the adhesive layer, the type and content of additives, surface treatment such as plasma treatment, or the surface roughness of the adhesive layer. The adhesive layer may include a rubber-based resin. Specifically, the rubber-based resin may be at least one selected from the group consisting of natural rubber (polyisoprene), epoxidized natural rubber, polyisobutylene rubber, epoxidized styrene block copolymer, ethylene propylene diene monomer (EPDM), and styrene-ethylene-butylene-styrene copolymer (SEBS). When the adhesive layer includes a rubber-based resin, the hydrophobic property of the adhesive layer may be further improved, so that the electrolyte resistance may be excellent. The adhesive strength of the above adhesive layer can be 200 gf / 25 mm or more. Specifically, the adhesive strength of the adhesive layer may be 200 gf / 25 mm or more, 210 gf / 25 mm or more, 220 gf / 25 mm or more, 230 gf / 25 mm or more, 240 gf / 25 mm or more, 250 gf / 25 mm or more, 260 gf / 25 mm or more, 270 gf / 25 mm or more, 280 gf / 25 mm or more, 290 gf / 25 mm or more, and 1,500 gf / 25 mm or less, 1,400 gf / 25 mm or less, 1,300 gf / 25 mm or less, 1,200 gf / 25 mm or less, 1,100 gf / 25 mm or less, 1,000 gf / 25 mm or less, 900 gf / 25 mm or less, 800 gf / 25 mm or less, It can be 700gf / 25mm or less, 600gf / 25mm or less, 500gf / 25mm or less, 400gf / 25mm or less, or 300gf / 25mm or less. For example, the adhesive strength of the adhesive layer can be 200gf / 25mm or more, preferably 200gf / 25mm to 1,500gf / 25mm, more preferably 220gf / 25mm to 1,000gf / 25mm, and even more preferably 250gf / 25mm to 500gf / 25mm. When the above range is satisfied, the adhesive film can be sufficiently strongly fixed to the adherend so that the adhesive film is not easily detached, and the electrolyte resistance and the liquid resistance of the adhesive film can be balanced. The above adhesive strength can be controlled by the type of adhesive constituting the adhesive layer, the degree of cross-linking, the type and content of additives added to the adhesive layer, and the surface roughness and surface treatment of the adhesive layer. Specifically, in order to control the adhesive strength of the adhesive layer, the adhesive layer may include at least one selected from the group consisting of a tackifier, a silane coupling agent, an inorganic filler such as nano silica, and an organic filler such as an elastomer as an additive. At this time, if the additive is a tackifier, the additive may be included in an amount of 1 to 50 wt% based on the total weight of the adhesive layer, if the additive is a silane coupling agent, the additive may be included in an amount of 0.1 to 2.0 wt% based on the total weight of the adhesive layer, if the additive is an inorganic filler, the additive may be included in an amount of 0.1 to 10 wt% based on the total weight of the adhesive layer, and if the additive is an organic filler, the additive may be included in an amount of 0.1 to 10 wt% based on the total weight of the adhesive layer. Alternatively, in terms of controlling the adhesive strength of the adhesive layer, the surface roughness of the adhesive layer may be 0.01 ㎛ to 2.0 ㎛ based on the average roughness (Ra). Alternatively, in order to control the adhesive strength of the adhesive layer, the adhesive layer may be surface treated by plasma treatment, flame treatment, or the like. The adhesive strength of the above adhesive layer may be 100 gf / 25 mm or more. Specifically, the internal electrolyte adhesive strength of the adhesive layer may be 100 gf / 25 mm or more, 110 gf / 25 mm or more, 120 gf / 25 mm or more, 130 gf / 25 mm or more, 140 gf / 25 mm or more, 150 gf / 25 mm or more, 160 gf / 25 mm or more, 170 gf / 25 mm or more, 180 gf / 25 mm or more, 190 gf / 25 mm or more, and 1,500 gf / 25 mm or less, 1,400 gf / 25 mm or less, 1,300 gf / 25 mm or less, 1,200 gf / 25 mm or less, 1,100 gf / 25 mm or less, 1,000 gf / 25 mm or less, 900 gf / 25 mm or less, 800 gf / 25 mm Below, it can be 700gf / 25mm or less, 600gf / 25mm or less, 500gf / 25mm or less, 400gf / 25mm or less, or 300gf / 25mm or less. When the above range is satisfied, even when the electrolyte and the adhesive film come into contact, the adhesive film can be fixed and positioned without being detached, thereby ensuring the safety of the battery. The above-mentioned adhesive strength of the electrolyte solution can be controlled by the contact angle of the adhesive layer, the degree of crosslinking of the adhesive included in the adhesive layer, the surface treatment of the adhesive layer, and the surface roughness. Meanwhile, the adhesive layer may have a electrolyte resistance index defined by the following Equation 1 of 3 or less, preferably 0.2 to 2, and more preferably 0.5 to 1. The electrolyte resistance index refers to a value that numerically expresses the degree to which the adhesive film can maintain its adhesive strength and shape when in contact with an electrolyte. When the electrolyte resistance index satisfies the above range, the adhesive film for a secondary battery according to the present invention can secure sufficient adhesive strength even when in contact with an electrolyte, and can suppress deformation in its shape as much as possible, thereby improving the appearance defect of the battery and enhancing the quality of the battery. [Formula 1] Meanwhile, the thickness of the adhesive layer may be 1 ㎛ to 12 ㎛, preferably 2 ㎛ to 12 ㎛, and more preferably 3 ㎛ to 10 ㎛. When the above range is satisfied, the adhesive layer can secure sufficient adhesive strength and improve the decrease in energy density of the secondary battery. Alternatively, according to one embodiment of the present invention, when the adhesive film is positioned on the welding portion where the electrode lead and the electrode tab of the secondary battery are connected, the thickness of the adhesive layer may be 3 µm to 12 µm, preferably 5 µm to 12 µm, and more preferably 8 µm to 10 µm. When the above range is satisfied, the bead of the welding portion can be sufficiently filled, so that the sealant layer can be sufficiently protected from the bead of the welding portion, and can have high adhesive strength for the welding portion. According to another embodiment of the present invention, when the adhesive film is positioned on the outer surface of the electrode assembly of the secondary battery, the thickness of the adhesive layer may be 1 ㎛ to 9 ㎛, preferably 1 ㎛ to 7 ㎛, and more preferably 1 ㎛ to 4 ㎛. When the above range is satisfied, the adhesive strength of the adhesive layer can be sufficiently secured while firmly fixing the laminated electrode assembly. According to another embodiment of the present invention, when the adhesive film is positioned on the folded area of ​​the sealing portion of the battery case of the secondary battery, the thickness of the adhesive layer may be 1 ㎛ to 9 ㎛, preferably 1 ㎛ to 7 ㎛, and more preferably 1 ㎛ to 4 ㎛. When the above range is satisfied, the sealing portion can be firmly fixed in a folded state, thereby improving the energy density of the secondary battery. Lithium secondary battery According to one embodiment of the present invention, a lithium secondary battery comprises an electrode assembly including a positive electrode, a negative electrode, and a separator; an electrode tab extending and protruding from each electrode plate of the electrode assembly; an electrode lead connected to the electrode tab by welding; the adhesive film described above; an electrolyte; and a battery case in which the electrode assembly is accommodated. Hereinafter, each component of the lithium secondary battery according to the present invention will be described in more detail. (1) Battery case FIG. 2 is an exploded assembly drawing of a lithium secondary battery that does not illustrate an adhesive film for a secondary battery according to the present invention. Referring to FIG. 2, the battery case (210) according to the present invention can serve to store the electrode assembly (260). At this time, the battery case can be applied in various ways depending on the shape, structure, and manufacturing method of the lithium secondary battery, but specifically, it can be applied to a cylindrical shape, a square shape, a pouch shape, etc. Preferably, the battery case (210) according to the present invention can be a pouch-shaped case. Referring to FIG. 2, a pouch-shaped battery case (210) can be manufactured by molding a pouch film laminate. The pouch-shaped battery case (210) can be sealed by housing an electrode assembly (260) inside and injecting an electrolyte. The above pouch film laminate may be formed by sequentially laminating a substrate layer, a gas barrier layer, and a sealant layer, but is not limited thereto. Specifically, the substrate layer is formed on the outermost layer of the pouch film laminate to protect the secondary battery from friction and collision with the outside. The substrate layer is made of a polymer and can electrically insulate the electrode assembly from the outside. The above-mentioned substrate layer may be made of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, and Teflon. Among them, the above-mentioned substrate layer is preferably made of polyethylene terephthalate (PET), nylon, or a combination thereof, which have wear resistance and heat resistance. The above gas barrier layer is laminated between the substrate layer and the sealant layer to secure the mechanical strength of the pouch, block the ingress or egress of gas or moisture from outside the secondary battery, and prevent electrolyte leakage from inside the pouch-type battery case. The gas barrier layer may be formed of a metal. For example, the gas barrier layer may be a metal thin film including at least one metal selected from the group consisting of aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti), and invar (INVAR), but is not limited thereto. The above sealant layer is intended to completely seal the inside of the pouch-shaped battery case by mutually thermally bonding at the sealing portion when the pouch-shaped battery case accommodating the electrode assembly inside is sealed. To this end, the sealant layer may be formed of a material having excellent thermal bonding strength. The sealant layer may be formed of a material having insulating, corrosion-resistant, and sealing properties. Specifically, since the sealant layer is in direct contact with the electrode assembly and / or the electrolyte inside the pouch-shaped battery case, it may be formed of a material having insulating and corrosion-resistant properties. In addition, since the sealant layer must completely seal the inside of the pouch-shaped battery case to block material movement between the inside and the outside, it may be formed of a material having high sealing properties (e.g., excellent thermal bonding strength). In order to secure such insulating, corrosion-resistant, and sealing properties, the sealant layer may be formed of a polymer material. The sealant layer may be made of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, and Teflon, and preferably may be made of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may be composed of cast polypropylene (CPP), acid modified polypropylene (Acid Modified Polypropylene, PPa), a polypropylene-ethylene copolymer, and / or a polypropylene-butylene-ethylene terpolymer. The pouch film laminate may be drawn and stretched by a punch or the like to manufacture a pouch-shaped battery case (210). As a result, the pouch-shaped battery case (210) may include a cup portion (222) and a receiving portion (224). The receiving portion (224) is a place for receiving an electrode assembly, and may mean a receiving space formed in a pocket shape on the inside of the cup portion (222) as the cup portion (222) is formed. According to one embodiment of the present invention, the pouch-type battery case (210) may include a first case (220) and a second case (230) as illustrated in FIG. 2. The first case (220) may include a receiving portion (224) capable of receiving an electrode assembly (260), and the second case (230) may cover the receiving portion (224) from above so that the electrode assembly (260) does not fall out 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. 2, but are not limited thereto and may be manufactured in various ways, such as being manufactured separately from each other. According to another embodiment of the present invention, when forming a cup portion in a pouch film laminate, two symmetrical cup portions (222, 232) can be drawn and formed adjacent to each other in one pouch film laminate. In this case, cup portions (222, 232) can be formed in each of the first case (220) and the second case (230) as illustrated in FIG. 2. After the electrode assembly (260) is accommodated in the receiving portion (224) provided in the cup portion (222) of the first case (220), the bridge portion (240) formed between the two cup portions (222, 232) can be folded so that the two cup portions (222, 232) face each other. In this case, the cup portion (232) of the second case (230) can accommodate the electrode assembly (260) from above. Accordingly, since two cup parts (222, 232) accommodate one electrode assembly (260), an electrode assembly (260) having a thicker thickness can be accommodated than when there is only one cup part (222). In addition, since one corner of the secondary battery (200) is formed by folding the pouch-type battery case (210), the number of corners to be sealed can be reduced when performing a sealing process later. Accordingly, the process speed of the pouch-type secondary battery (200) can be improved, and the number of sealing processes can be reduced. The pouch-type battery case (210) can be sealed while housing the electrode assembly (260) so that a part of the electrode lead (280) described later, i.e., a terminal part, is exposed. Specifically, when the electrode lead (280) is connected to the electrode tab (270) of the electrode assembly (260) and an insulating part (290) is formed on a part of the electrode lead (280), the electrode assembly (260) can be housed in the receiving part (224) provided in the cup part (222) of the first case (220), and the second case (230) can cover the receiving part (224) from above. Then, an electrolyte can be injected into the interior of the receiving part (224), and the sealing part (250) formed on the edges of the first case (220) and the second case (230) can be sealed. 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 for sealing the sealing portion (250) 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 by heat bonding. At this time, the sealing portion can be formed by folding in the direction of the receiving portion to secure the energy density of the lithium secondary battery. (2) Electrode assembly An electrode assembly according to the present invention includes a positive electrode, a separator, and a negative electrode. Referring to FIG. 2, an electrode assembly (260) may be inserted into a pouch-shaped battery case (210) and sealed by the pouch-shaped battery case (210) after electrolyte injection. The electrode assembly (260) may be formed by sequentially stacking an anode, a separator, and a cathode. 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. 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 or copper. The slurry may be formed by stirring a granular active material, an auxiliary conductor, a binder, and a conductive agent while a solvent is added. The solvent may be removed in a subsequent process. A slurry containing an electrode active material and a binder and / or a conductive material is applied to a positive electrode current collector and a negative electrode current collector to manufacture a positive electrode and a negative electrode, and the positive electrode and negative electrode are laminated on both sides of a separator, thereby manufacturing an electrode assembly (260) in a predetermined shape. The types of the electrode assembly (260) may include, but are not limited to, a stack type, a jelly roll type, a stack and folding type, etc. (3) Electrode tab An electrode tab according to the present invention can extend and protrude from the electrode plate of each electrode of the electrode assembly. Referring to FIG. 2, the electrode tabs (270) are respectively connected to the positive and negative electrodes of the electrode assembly (260), and protrude outwardly from the electrode assembly (260) to serve as a path through which electrons can move between the inside and the outside of the electrode assembly (260). The electrode current collector included in the electrode assembly (260) may be composed of a portion where an electrode active material is applied and a terminal portion where the electrode active material is not applied, i.e., a non-coated portion. The electrode tabs (270) may be formed by cutting the non-coated portion or by connecting a separate conductive member to the non-coated portion by ultrasonic welding, etc. As illustrated in FIG. 2, the electrode tabs (270) may protrude in different directions from each other in the electrode assembly (260), but are not limited thereto, and may be formed to protrude in various directions, such as protruding side by side in the same direction from one side. (4) Electrode lead Referring to FIG. 2, the electrode lead (280) can supply electricity to the outside of the secondary battery (200). The electrode lead (280) can be connected to the electrode tab (270) of the electrode assembly (260) by welding, for example, by spot welding. 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). The electrode lead (280) may include a positive lead (282) having one end connected to the positive tab (272) and extending in the protruding direction of the positive tab (272), and a negative lead (284) having one end connected to the negative tab (274) and extending in the protruding direction of the negative tab (274). Both the positive lead (282) and the negative lead (284) may have other ends protruding outward from the battery case (210). Accordingly, electricity generated inside the electrode assembly (260) may be supplied to the outside. In addition, since the positive tab (272) and the negative tab (274) are formed to protrude in various directions, the positive lead (282) and the negative lead (284) may also extend in various directions, respectively. The positive lead (282) and the negative lead (284) may be made of different materials. That is, the positive electrode lead (282) may be made of the same aluminum (Al) material as the positive electrode collector, and the negative electrode lead (284) may be made of the same copper (Cu) material as the negative electrode collector or a copper material coated with nickel (Ni). A portion of the electrode lead (280) protruding outside the battery case (210) may be a terminal portion and may be electrically connected to an external terminal. The electrode lead (280) may include an insulating portion (190). The insulating portion (290) prevents electricity generated from the electrode assembly (260) from flowing to the battery case (210) through the electrode lead (280) and can maintain the sealing of the battery case (210). To this end, the insulating portion (290) can be formed of a non-conductive material that does not conduct electricity well. In general, the insulating portion (290) is often made of an insulating tape or film that is easy to attach to the electrode lead (280) and has a relatively thin thickness, but is not limited thereto, and any material capable of insulating the electrode lead (280) can be used. The insulating portion (290) may be arranged to surround the outer surface of the electrode lead (280). 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 heat-sealed, and may adhere the electrode lead (280) to the battery case (210). (5) Electrolyte The electrolyte used in the present invention may include various electrolytes that can be used in lithium secondary batteries, for example, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., and the type thereof is not particularly limited. Specifically, the electrolyte may include an organic solvent and a lithium salt. As the organic solvent, any solvent that can act as a medium through which ions involved in the electrochemical reaction of the battery can move may be used without particular limitation. Specifically, the organic solvent may include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; Examples of solvents that can be used include carbonate solvents, such as dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents, such as ethyl alcohol and isopropyl alcohol; nitriles, such as R-CN (wherein R represents a C2 to C20 linear, branched, or cyclic hydrocarbon group, and may include a double-bonded aromatic ring or an ether bond); amides, such as dimethylformamide; dioxolanes, such as 1,3-dioxolane; and sulfolanes. Among these, a carbonate solvent is preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) is more preferable. The lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2. LiCl, LiI, or LiB(C2O4)2. It is preferable to use the concentration of the lithium salt in the range of 0.1 to 5.0 M, preferably 0.1 to 3.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively. In addition to the electrolyte components, the electrolyte may further contain additives for the purposes of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. For example, the additives may include, but are not limited to, haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexamethylphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxy ethanol, or aluminum trichloride. The additives may be contained in an amount of 0.1 to 10 wt%, preferably 0.1 to 5 wt%, based on the total weight of the electrolyte. (6) Adhesive film Since the structure and components of the above adhesive film are the same as described above, a detailed description is omitted. Figure 3 is an exploded assembly diagram showing a lithium secondary battery according to one embodiment of the present invention. Referring to FIG. 3, the adhesive film (10) for the secondary battery may be positioned on the welding portion where the electrode lead (280) and the electrode tab (270) are connected. At this time, since the adhesive film is positioned on the welding portion, the sealant layer of the pouch film, the separator, or the electrode may be prevented from being damaged by the bead formed at the welding portion, and the resulting deterioration of the insulation of the battery case may be prevented. Figure 4 is an exploded assembly diagram showing a lithium secondary battery according to another embodiment of the present invention. Referring to FIG. 4, the adhesive film (10) for the secondary battery may be positioned on the outer surface of the electrode assembly (260). At this time, when the adhesive film (10) is positioned on the outer surface of the electrode assembly (260), the secondary battery can be prevented from being damaged by collision, and a short circuit can be prevented from occurring due to a mismatch between the positive and negative electrodes. FIG. 5 is a perspective view showing a lithium secondary battery according to another embodiment of the present invention. Referring to FIG. 5, the adhesive film (10) for the secondary battery may be positioned on the folded area of ​​the sealing portion (20) of the battery case (210). When the adhesive film is positioned on the folded area of ​​the sealing portion, the edge of the sealing portion is fixed in a folded state, so that the energy density of the secondary battery can be increased and the vent pressure can be improved. However, the adhesive film for the secondary battery is not limited to the above-described position. Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. <Adhesive film for welding protection> Example 1 An adhesive film for a secondary battery was manufactured by laminating a 7 ㎛ thick natural rubber (polyisoprene) film on one side of a 40 ㎛ thick non-stretched polypropylene (casting polypropylene) film. Here, the non-stretchy polypropylene film is the outer insulating layer and the natural rubber film is the adhesive layer. Example 2 An adhesive film for a secondary battery was manufactured by laminating a 7 ㎛ thick natural rubber (polyisoprene) film on one side of a 60 ㎛ thick non-stretched polypropylene (casting polypropylene) film. Here, the non-stretchy polypropylene film is the outer insulating layer and the natural rubber film is the adhesive layer. Example 3 An adhesive film for a secondary battery was manufactured by laminating a 10 ㎛ thick natural rubber (polyisoprene) film on one side of a 100 ㎛ thick non-stretched polypropylene (casting polypropylene) film. Here, the non-stretchy polypropylene film is the outer insulating layer and the natural rubber film is the adhesive layer. Example 4 An adhesive film for a secondary battery was manufactured by laminating a 7-㎛ thick polyisobutylene film on one side of a 60-㎛ thick cast polypropylene film. Here, the non-stretchy polypropylene film is the outer insulating layer and the polyisobutylene film is the adhesive layer. Example 5 An adhesive film for a secondary battery was manufactured by laminating a 7-㎛ thick ethylene propylene diene monomer rubber (EPDM rubber) film on one side of a 60-㎛ thick cast polypropylene film. Here, the non-stretchy polypropylene film is the outer insulating layer and the ethylene propylene diene monomer rubber film is the adhesive layer. Comparative Example 1 An adhesive film for a secondary battery was manufactured by laminating a 7-㎛ thick polystyrene copolymer film on one side of a 60-㎛ thick cast polypropylene film. Here, the non-stretchy polypropylene film is the outer insulating layer and the insulating layer, and the polystyrene copolymer film is the adhesive layer. Comparative Example 2 An adhesive film for a secondary battery was manufactured by laminating a 7-㎛ thick acrylonitrile butadiene styrene (ABS) film on one side of a 60-㎛ thick cast polypropylene film. Here, the non-stretchy polypropylene film is the outer insulating layer, and the acrylonitrile butadiene styrene film is the adhesive layer. Comparative Example 3 An adhesive film for a secondary battery was manufactured by laminating an acrylic copolymer film having a thickness of 7 ㎛ on one side of a cast polypropylene film having a thickness of 60 ㎛. Here, the non-stretchy polypropylene film is the outer insulating layer, and the acrylonitrile butadiene styrene film is the adhesive layer. <Adhesive film for battery fixation> Example 6 An adhesive film for a secondary battery was manufactured by laminating a 3-㎛ thick natural rubber (polyisoprene) film on one side of a 20-㎛ thick polyethylene terephthalate (PET) film. Here, the polyethylene terephthalate film is the outer insulating layer and the natural rubber film is the adhesive layer. Example 7 An adhesive film for a secondary battery was manufactured by laminating a 3-㎛ thick natural rubber (polyisoprene) film on one side of a 17-㎛ thick polyethylene terephthalate (PET) film. Here, the non-stretchy polypropylene film is the outer insulating layer and the natural rubber film is the adhesive layer. Comparative Example 4 An adhesive film for a secondary battery was manufactured by laminating a 3-㎛ thick natural rubber (polyisoprene) film on one side of a 20-㎛ thick polyethylene terephthalate (PET) film. At this time, the natural rubber film was manufactured by adding a silane coupling agent (vinyltrimethoxysilane) to natural rubber. Here, the polyethylene terephthalate film is an outer insulating layer, and the natural rubber film is an adhesive layer. Comparative Example 5 An adhesive film for a secondary battery was manufactured by laminating a 3-㎛ thick natural rubber (polyisoprene) film on one side of a 20-㎛ thick polyethylene terephthalate (PET) film. At this time, the natural rubber film was manufactured by subjecting natural rubber to plasma surface treatment. Here, the polyethylene terephthalate film is an outer insulating layer, and the natural rubber film is an adhesive layer. Comparative Example 6 An adhesive film for a secondary battery was manufactured by laminating a 5-㎛ thick acrylic copolymer film on one side of a 17-㎛ thick polyethylene terephthalate (PET) film. Here, the polyethylene terephthalate film is an outer insulating layer, and the acrylic copolymer film is an adhesive layer. Experimental Example 1: Measurement of adhesive layer contact angle, adhesive force, electrolyte adhesive force, and electrolyte index 1) Measurement of the contact angle of the adhesive layer Using a Phoenix mt from SEO Co., Ltd., one drop of distilled water was dropped onto the adhesive layer of each of the adhesive films manufactured in Examples 1 to 7 and Comparative Examples 1 to 6 at room temperature (25°C), and the angle formed between the surface and the interface of the water droplet was measured within 5 seconds. The results are shown in Table 1 below. 2) Measuring the adhesive strength of the adhesive layer Each of the adhesive films manufactured in Examples 1 to 7 and Comparative Examples 1 to 6 was cut to a size of 25 mm × 150 mm. The opposite side of the adhesive layer in contact with the outer insulating layer of the cut adhesive film was pressed onto a SUS304 substrate using a 2 kg roller. Thereafter, the adhesive film was peeled at a peeling speed of 300 mm / min and a peeling angle of 180° at 25°C. The adhesive strength at this time was measured using ASTM D 3330. The measurement results are shown in Table 1 below. 3) Measurement of the adhesive strength of the adhesive layer Each of the adhesive films manufactured in Examples 1 to 7 and Comparative Examples 1 to 6 was cut to a size of 25 mm × 150 mm. The cut adhesive films were impregnated in an electrolyte and then stored at 60°C for 24 hours. Thereafter, the impregnated adhesive films were taken out, and the opposite side of the adhesive layer in contact with the outer insulating layer was pressed onto a SUS304 substrate using a 2 kg roller. Thereafter, the adhesive films were peeled at a peeling speed of 300 mm / min and a peeling angle of 180° at 25°C. The adhesive strength at this time was measured using ASTM D 3330. The measurement results are shown in Table 1 below. 4) Measurement of the internal electrolyte index The contact angle, adhesive force, and electrolyte resistance of the adhesive films manufactured in Examples 1 to 7 and Comparative Examples 1 to 6 measured above were used to measure the electrolyte resistance index defined by Equation 1 below. The measurement results are shown in Table 1 below. [Formula 1] 5) Wetting tension measurement The wetting tension of the adhesive layer in the adhesive films manufactured in Examples 1 to 7 and Comparative Examples 1 to 6 was measured according to the method compliant with JIS K 6768:1999. Specifically, after applying the solution to the surface of the adhesive layer according to the method compliant with JIS K 6768:1999, the state in which the solution spreads or forms beads on the surface was observed, and the highest surface tension value at which the solution spreads uniformly on the surface of the adhesive layer for 2 seconds or more was measured as the wetting tension of the adhesive layer using a Phoenix mt device from SEO Corporation. The measurement results are shown in Table 1 below. Adhesive layer contact angle [˚] Adhesive force [gf / 25mm] Electrolyte adhesive force [gf / 25mm] Electrolyte wetting tension [mN / m] Example 11202903000.80620 Example 21203103200.80720 Example 31203503600.81020 Example 41123303200.92127 Example 51013603501.01826 Example 61204004900.68022 Example 71204205200.67321 Comparative example 1925001803.01934 Comparative example 2817001505.76138.5 Comparative example 3701,0501693.75041Comparative Example 4905501504.07432Comparative Example 5705005014.28638Comparative Example 6707002835.71442 Referring to Table 2 above, it can be confirmed that the adhesive films manufactured in Examples 1 to 7 having a contact angle of the adhesive layer of 100° or more and a wetting tension of less than 30 mN / m maintain a certain level or higher of adhesive strength even after immersion in an electrolyte at high temperature for 24 hours, but the adhesive films manufactured in Comparative Examples 1 to 6 having a contact angle of the adhesive layer of less than 100° and a wetting tension of 30 mN / m or more show a greatly reduced adhesive strength of the adhesive layer after immersion in an electrolyte at high temperature for 24 hours. Experimental Example 2: Evaluation of peeling and wrinkle occurrence in adhesive film 1) Evaluation of whether the adhesive film for welding protection is detached An electrode assembly was manufactured by stacking and laminating the positive and negative electrodes and the porous polyethylene separator. Thereafter, electrode leads were welded to the protruding electrode tabs of the positive and negative electrodes of the electrode assembly. Thereafter, each of the adhesive films manufactured in Examples 1 to 5 and Comparative Examples 1 to 3 was attached to the welding portions of the electrode tab and the electrode lead, and the electrolyte and electrode assembly were placed in a pouch-type battery case and sealed to manufacture a pouch-type lithium secondary battery. At this time, the electrolyte used was an electrolyte manufactured by adding 1.0 M LiPF6 to a solvent containing ethylene carbonate:ethyl methyl carbonate:dimethyl carbonate mixed in a volume ratio of 3:3:4. The pouch-type lithium secondary batteries manufactured including the adhesive films manufactured in Examples 1 to 5 and Comparative Examples 1 to 3 were stored at 60°C for 24 hours. Thereafter, each pouch-type lithium secondary battery was disassembled and visually observed to determine whether the adhesive films manufactured in Examples 1 to 7 and Comparative Examples 1 to 3 were detached. The results are shown in Table 2 below. O: The adhesive film is peeled off. X: The adhesive film does not detach. 2) Evaluation of whether wrinkles occur in the adhesive film for fixing the battery An electrode assembly was manufactured by stacking and laminating the positive and negative electrodes and the porous polyethylene separator. Thereafter, electrode leads were welded to the protruding electrode tabs of the positive and negative electrodes of the electrode assembly. Thereafter, each of the adhesive films manufactured in Examples 6 to 7 and Comparative Examples 4 to 6 was attached to the welding portions of the electrode tab and the electrode lead, and the electrolyte and electrode assembly were placed in a pouch-type battery case and sealed to manufacture a pouch-type lithium secondary battery. At this time, the electrolyte used was an electrolyte manufactured by adding 1.0 M LiPF6 to a solvent containing ethylene carbonate:ethyl methyl carbonate:dimethyl carbonate mixed in a volume ratio of 3:3:4. The pouch-type lithium secondary batteries manufactured including the adhesive films manufactured in Examples 6 to 7 and Comparative Examples 4 to 6 were stored at 60°C for 24 hours. Thereafter, each pouch-type lithium secondary battery was disassembled and visually observed to determine whether wrinkles occurred in the adhesive films manufactured in Examples 1 to 7 and Comparative Examples 1 to 3. The results are shown in Table 2 below. O: Wrinkles appear on the adhesive film. X: The adhesive film does not wrinkle. Whether the adhesive film detaches Whether the adhesive film wrinkles occur Example 1X-Example 2X-Example 3X-Example 4X-Example 5X-Example 6-X Example 7-X Comparative Example 1O-Comparative Example 2O-Comparative Example 3O-Comparative Example 4-O Comparative Example 5-O Comparative Example 6-O Referring to Table 2 above, it can be confirmed that the adhesive films manufactured in Examples 1 to 5 do not detach in a high temperature environment of 60°C even when used as adhesive films for welding protection in the manufacture of lithium secondary batteries, but the adhesive films manufactured in Comparative Examples 1 to 3 detach when used as adhesive films for welding protection in the manufacture of lithium secondary batteries. In addition, the adhesive films manufactured in Examples 6 to 7 do not wrinkle in a high temperature environment of 60°C even when used as adhesive films for battery fixing in the manufacture of lithium secondary batteries, but the adhesive films manufactured in Comparative Examples 4 to 6 wrinkle in a high temperature environment of 60°C when used as adhesive films for battery fixing in the manufacture of lithium secondary batteries. Through this, it can be understood that the adhesive films manufactured in Examples 1 to 7 have excellent electrolyte resistance and function excellently in a high temperature environment of 60°C as adhesive tapes for welding protection or battery fixing. (Explanation of symbols) 10: Adhesive film 11: Outer insulation layer 12: Adhesive layer 100: Pouch film laminate 200: Pouch-type secondary battery 210: Pouch-type case 220: Case 1 222: Cup part 224: Reception area 230: Case 2 232: Cup part 240: Bridge section 250: Sealing part 260: Electrode assembly 270: Electrode tab 272: Bipolar tab 274: Negative tab 280: Electrode Lead 282: Bipolar Lead 284: Negative lead 290: Insulation

Claims

1. An outer insulating layer; and an adhesive layer positioned on one surface of the outer insulating layer; The contact angle of the above adhesive layer is 100° or more, An adhesive film for a secondary battery, wherein the wetting tension of the adhesive layer is less than 30 mN / m.

2. In paragraph 1, An adhesive film for a secondary battery, wherein the adhesive layer comprises a rubber-based resin.

3. In paragraph 2, An adhesive film for a secondary battery, wherein the rubber-based resin is at least one selected from the group consisting of natural rubber, epoxidized natural rubber, polyisobutylene rubber, epoxidized styrene block copolymer, ethylene propylene diene monomer rubber, and styrene-ethylene-butylene-styrene copolymer.

4. In paragraph 1, An adhesive film for a secondary battery, wherein the outer insulating layer is at least one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyimide, non-stretched polypropylene, high-density polyethylene, and low-density polyethylene.

5. In paragraph 1, The above adhesive layer is an adhesive film for a secondary battery having an adhesive strength of 200 gf / 25 mm or more.

6. In paragraph 1, The above adhesive layer is an adhesive film for a secondary battery, wherein the adhesive strength of the internal electrolyte is 100 gf / 25 mm or more.

7. In paragraph 1, The adhesive layer is an adhesive film for a secondary battery, wherein the electrolyte index defined by the following equation 1 is 3 or less. [Formula 1] 8. Electrode assembly including anode, cathode and separator; Electrode tabs protruding from each plate of the electrode assembly; Electrode leads connected by welding to the above electrode tabs; An adhesive film for a secondary battery according to any one of claims 1 to 7; electrolyte; and A lithium secondary battery comprising a battery case in which the electrode assembly and the electrolyte are stored.

9. In paragraph 8, A lithium secondary battery, wherein the adhesive film for the secondary battery is positioned on a welding portion where the electrode lead and the electrode tab are connected.

10. In paragraph 8, A lithium secondary battery, wherein the adhesive film for the secondary battery is positioned on the outer surface of the electrode assembly.

11. In paragraph 8, A lithium secondary battery, wherein the adhesive film is positioned on a folded area of ​​a sealing portion of the battery case.

12. In paragraph 8, The above battery case is a pouch-type battery case, a lithium secondary battery.

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