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

Abstract

The pouch film laminate according to the present invention comprises a first base layer, a second base layer, a gas barrier layer, and a sealant layer laminated in this order, and the moisture content index of the second base layer, represented by the following formula 1, is 17,000 ppm g / cm 3 The following is the result. [Formula 1] Moisture content index of the second base layer = Moisture content per unit weight of the pouch film laminate (ppm) × Density of the pouch film laminate (g / cm 3 ) × thickness of pouch film laminate (μm) / thickness of second base layer (μm)

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0015125, filed February 3, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a pouch film laminate and a pouch-type secondary battery produced by molding the same. [Background technology]

[0003] Secondary batteries are used in a wide range of fields, from small products such as digital cameras, DVD players, MP3 players, mobile phones, PDAs, portable game devices, power tools, and e-bikes to large products requiring high output such as electric vehicles and hybrid vehicles, as well as power storage devices and backup power storage devices for storing surplus generated power and new renewable energy. Types of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries.

[0004] A secondary battery can be manufactured by placing an electrode assembly, in which a positive electrode, a negative electrode, and a separator interposed between them are alternately stacked, in a battery case, injecting an electrolyte, and then sealing the battery case. Secondary batteries can be classified into pouch types, can types, etc., depending on the material of the case that houses the electrode assembly.

[0005] A pouch-type secondary battery can be manufactured by pressing a flexible pouch film laminate to form a cup, placing an electrode assembly in the receiving space inside the cup, and sealing the seal. The pouch film laminate is formed of multiple layers, including a metal gas barrier layer on one side of which a polymer film such as polyethylene terephthalate is laminated, and a sealant layer made of a thermoplastic polyolefin resin is laminated on the other side. When the pouch-type battery case is sealed, the sealant layers are thermally bonded to each other to form the seal.

[0006] Recently, as the capacity of pouch-type secondary batteries has increased, the demand for pouches with excellent moldability has been increasing. When a thick gas barrier layer is formed to produce a pouch with excellent moldability, a problem arises in that the sealant layer does not easily melt when sealing the pouch-type battery case. To solve this problem, methods have been used to increase the heat applied when sealing the pouch-type battery case by increasing the sealing temperature and / or sealing time. However, increasing the sealing temperature to 220°C or higher can cause deformation due to melting of the base layer, and extending the sealing time can increase the production time (tact time), resulting in reduced productivity. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention is intended to solve the above problems, and provides a pouch film laminate that can prevent deformation of the seal portion and shorten the sealing time during the process of sealing a pouch-type battery case manufactured from the pouch film laminate, thereby ensuring both sealing quality and processability. [Means for solving the problem]

[0008] According to one embodiment of the present invention, a coating film is provided which includes a first substrate layer, a second substrate layer, a gas barrier layer, and a sealant layer, which are laminated in this order, and the moisture content index of the second substrate layer, represented by the following formula 1, is 17,000 ppm g / cm 3 There is provided a pouch film laminate, which is: [Formula 1] Moisture content index of the second base layer = Moisture content per unit weight of the pouch film laminate (ppm) × Density of the pouch film laminate (g / cm 3 ) × thickness of pouch film laminate (μm) / thickness of second base layer (μm)

[0009] The moisture content per unit weight of the pouch film laminate can be 1,500 ppm or less.

[0010] The thickness of the first base layer can be 10 μm to 50 μm. The first base layer can include a polyester film. Specifically, the first base layer can include at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

[0011] The thickness of the second substrate layer may be 10 μm to 50 μm. The second substrate layer may include a polyamide film. Specifically, the second substrate layer 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. The melting temperature of the second substrate layer may be 220°C or higher.

[0012] The thickness of the gas barrier layer can be 30 μm to 100 μm.

[0013] The gas barrier layer may include aluminum.

[0014] The thickness of the sealant layer can be from 30 μm to 130 μm.

[0015] According to another embodiment of the present invention, there is provided a pouch-type battery case manufactured by molding the above-mentioned pouch film laminate.

[0016] According to another embodiment of the present invention, there is provided a pouch-type secondary battery including: a pouch-type battery case manufactured by molding the above-described pouch film laminate; and an electrode assembly housed in the pouch-type battery case. [Effects of the Invention]

[0017] In the present invention, the moisture content index of the second base layer represented by the above formula 1 is 17,000 ppm g / cm 3 By satisfying the following conditions, even when a pouch-type battery case manufactured from the pouch film laminate is sealed at a temperature of 220°C or higher, the generation of bubbles due to evaporation of moisture in the second base material layer can be suppressed, deformation of the sealed portion can be prevented, and the sealing time can be shortened. As a result, the sealing quality and processability of the pouch-type battery case manufactured from the pouch film laminate of the present invention can be ensured, and the durability and life characteristics of the pouch-type secondary battery can be improved. [Brief explanation of the drawings]

[0018] The drawings attached to the specification illustrate preferred embodiments of the present invention and, together with the above-described content of the invention, serve to further understand the technical concept of the present invention, and the present invention should not be interpreted as being limited solely to the matters shown in such drawings.

[0019] [Figure 1] 1 is a cross-sectional view of a pouch film laminate according to the present invention. [Figure 2] 1 is an exploded view of a pouch-type secondary battery according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0020] The advantages and features of the present invention, as well as methods for achieving them, will become clearer with reference to the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be embodied in various different forms. The present embodiments are provided to fully disclose the present invention and to fully convey the scope of the invention to those skilled in the art to which the present invention pertains. The present invention is defined only by the claims. The same reference symbols refer to the same elements throughout the specification.

[0021] Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used in the sense that can be commonly understood by a person having ordinary skill in the art to which the present invention belongs. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless they are clearly and specifically defined.

[0022] The terms used in this specification are for the purpose of describing embodiments and are not intended to limit the present invention. In this specification, the singular includes the plural unless otherwise stated in the text. The words "comprises" and / or "comprising" used in this specification do not exclude the presence or addition of one or more other elements in addition to the elements mentioned.

[0023] In this specification, when a part is said to include a certain component, this does not mean that it may further include other components, unless specifically stated to the contrary.

[0024] In this specification, the phrase "A and / or B" means A, B, or A and B.

[0025] In this specification, "%" means % by weight unless expressly indicated otherwise.

[0026] In this specification, the moisture content per unit weight of the pouch film laminate was measured by cutting the pouch film laminate into a size of 50 mm x 40 mm and then measuring the weight of moisture contained in the pouch film laminate per unit weight of the pouch film laminate (μg / g = ppm) using a Karl Fischer moisture meter at 150°C.

[0027] Pouch film laminate The pouch film laminate according to the present invention comprises a first substrate layer, a second substrate layer, a gas barrier layer, and a sealant layer laminated in this order, and the moisture content index of the second substrate layer, as represented by the following formula 1, is 17,000 ppm g / cm 3 The following is the result.

[0028] [Formula 1] Moisture content index of the second base layer = Moisture content per unit weight of the pouch film laminate (ppm) × Density of the pouch film laminate (g / cm 3 ) × thickness of pouch film laminate (μm) / thickness of second base layer (μm)

[0029] In conventional pouch film laminates, although the first substrate layer prevents moisture from penetrating from outside the pouch, moisture from outside the pouch can pass through the first substrate layer and reach the second substrate layer due to limitations in its thickness and material. In this case, the moisture can easily be absorbed into the second substrate layer by forming hydrogen bonds with functional groups (e.g., amide structures) in the polymer contained in the second substrate layer. As a result, when conventional pouch film laminates are sealed at high temperatures, the moisture absorbed in the second substrate layer evaporates, causing bubbles to form in the second substrate layer, which can deform and damage the sealed portion of the pouch, resulting in a decrease in the insulating properties of the pouch.

[0030] The present invention solves the above problem by reducing the moisture content of the pouch film laminate to a predetermined level or less. Specifically, the pouch film laminate according to the present invention has a moisture content index of the second substrate layer, as expressed by Equation 1, of 17,000 ppm g / cm. 3As a result, even when the pouch film laminate of the present invention is sealed at high temperatures, the generation of bubbles due to evaporation of moisture in the second base material layer can be suppressed, damage to the seal portion can be prevented, and the durability and life characteristics of the pouch-type secondary battery can be improved.

[0031] In the present invention, the moisture content index of the second base layer represented by the formula 1 is 17,000 ppm g / cm 3 Specifically, 1,000 ppm g / cm 3 ~17,000 ppm g / cm 3 , more specifically 1,000 ppm·g / cm 3 ~16,000 ppm g / cm 3 Here, the moisture content index of the second substrate layer is the weight of moisture contained in the second substrate layer per unit volume of the second substrate layer (ppm g / cm 3 ) means that the moisture content index of the second base layer is 17,000 ppm g / cm 3 In the case of over 220°C, when the pouch-type battery case manufactured from the pouch film laminate is sealed at a temperature of 220°C or higher to ensure sufficient heat is supplied within the required production time, the moisture contained in the second base material layer evaporates, causing bubbles to form in the second base material layer, which can deform and damage the seal, resulting in a decrease in the insulating properties of the pouch.

[0032] The moisture content per unit weight of the pouch film laminate according to the present invention may be 1,500 ppm or less, specifically 100 ppm to 1,500 ppm, and more specifically 100 ppm to 1,000 ppm. Here, the moisture content per unit weight of the pouch film laminate refers to the weight of moisture contained in the pouch film laminate per unit weight of the pouch film laminate (μg / g = ppm). When the moisture content per unit weight of the pouch film laminate satisfies the above numerical range, the moisture content in the second base layer of the pouch film laminate can be relatively reduced. As a result, even when the pouch film laminate is sealed at temperatures above 220°C, the generation of bubbles due to evaporation of moisture in the second base layer can be suppressed, preventing damage to the seal. Meanwhile, the moisture content per unit weight of the pouch film laminate may vary depending on the amount of moisture in the air in a chamber in which the pouch film laminate is stored and / or the exposure time of the pouch film laminate in air, but the method for controlling the moisture content is not limited thereto.

[0033] 1 is a cross-sectional view of a pouch film laminate 100 according to the present invention. Each component of the pouch film laminate 100 according to the present invention will be described in more detail below with reference to FIG.

[0034] (1) Base material layer The substrate layer 110 is formed as the outermost layer of the pouch film laminate 100 to protect the secondary battery from external friction and impact. The substrate layer 110 is made of a polymer and can electrically insulate the electrode assembly from the outside.

[0035] The thickness of the base material layer 110 can be 5 μm to 100 μm, specifically 7 μm to 70 μm, and more specifically 25 μm to 60 μm. When the thickness of the base material layer 110 satisfies this range, the external insulation is excellent, the overall thickness of the pouch is not large, and the energy density relative to the volume of the secondary battery can be excellent.

[0036] The substrate layer 110 according to the present invention may have a composite membrane structure formed by layers of two or more materials, and an adhesive layer may be further formed between each layer in the composite membrane structure.

[0037] Specifically, the substrate layer 110 according to the present invention may include a first substrate layer 112 and a second substrate layer 114. In this case, the first substrate layer 112 may be a layer disposed as the outermost layer of the pouch film laminate, and the second substrate layer 114 may be a layer disposed between the first substrate layer 112 and the gas barrier layer 120. The first substrate layer 112 and the second substrate layer 114 may be made of materials different in material and / or physical properties. An interface may exist between the first substrate layer 112 and the second substrate layer 114. This means that the first substrate layer 112 and the second substrate layer 114 are different layers and may be formed separately.

[0038] The first base material layer 112 and the second base material layer 114 will now be described in more detail.

[0039] 1) First base layer As described above, the first base layer 112 may be the outermost layer of the pouch film laminate, and in this case, the first base layer 112 may serve to prevent moisture from penetrating from outside the pouch.

[0040] The first base layer 112 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, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon (registered trademark), and glass fiber. Preferably, the first base layer 112 may include a polyester film having abrasion resistance and heat resistance. For example, the first base layer 112 may include at least one material selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, but is not limited thereto.

[0041] The thickness of the first base layer 112 can be 10 μm to 50 μm, specifically 10 μm to 40 μm, and more specifically 12 μm to 25 μm. When the thickness of the first base layer 112 satisfies the above numerical range, the insulating properties and formability of the pouch can be ensured, and the penetration of moisture into the inside of the pouch film laminate can be effectively suppressed. In addition, the overall thickness of the pouch is not large, and the energy density relative to the volume of the secondary battery is excellent.

[0042] 2) Second base material layer As described above, the second base material layer 114 can be a layer disposed between the first base material layer 112 and the gas barrier layer 120. In this case, the second base material layer 114 can play a role in improving the formability of the pouch.

[0043] The second base material layer 114 may include a polyamide film. For example, the second base material layer 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. Preferably, the second base material layer 114 may include nylon 6, which has the advantage of improving the formability of the pouch due to the excellent stretchability of nylon 6.

[0044] The thickness of the second base layer 114 can be 10 μm to 50 μm, specifically 10 μm to 40 μm, and more specifically 15 μm to 35 μm. When the thickness of the second base layer 114 satisfies the above numerical range, the formability of the pouch can be ensured, and a decrease in the energy density relative to the volume of the secondary battery caused by an excessively thick pouch film laminate can be prevented.

[0045] The second substrate layer 114 may contain metal oxide particles. The metal oxide particles are hydroxylated by reacting with moisture that has flowed into the second substrate layer 114, thereby removing moisture from the second substrate layer 114. The metal oxide particles may contain at least one selected from the group consisting of CaO, MnO, SrO, MgO, and ZnO. Preferably, the metal oxide particles may contain at least one of CaO and MgO, which are advantageous for hydroxylation with moisture.

[0046] The second base layer 114 may further include an additive. By including an additive in the second base layer 114, it is possible to change the physical properties of the second base layer 114. For example, at least one of carbon fiber, glass fiber, and aramid fiber may be added as an additive to adjust the tensile strength of the second base layer 114.

[0047] (2) Gas barrier layer The gas barrier layer 120 is laminated between the base layer 110 and the sealant layer 130 to ensure the mechanical strength of the pouch, block the entry and exit of gas or moisture from outside the secondary battery, and prevent electrolyte leakage from inside the pouch-type battery case.

[0048] The gas barrier layer 120 may be formed of a metal, such as, but not limited to, a thin metal film containing one or more metals selected from the group consisting of aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti), and invar.

[0049] According to one embodiment of the present invention, the gas barrier layer 120 may be formed of an aluminum alloy thin film. Forming the gas barrier layer 120 using an aluminum alloy thin film can ensure a certain level of mechanical strength, light weight, and the electrochemical properties of the electrode assembly and electrolyte, as well as heat dissipation. The aluminum alloy thin film may contain elements other than aluminum (Al). For example, the aluminum alloy thin film may contain one or more elements selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0050] As another example, the gas barrier layer 120 may be formed of a stainless steel thin film. Specifically, the gas barrier layer 120 may be manufactured by molding and / or processing a stainless steel thin film. A gas barrier layer 120 made of stainless steel has relatively low thermal conductivity, which is effective in preventing or delaying heat diffusion to other cells during thermal runaway. Furthermore, its relatively high toughness can prevent cracks from occurring in the pouch during use of the pouch-type battery. The stainless steel may contain elements other than iron (Fe), such as one or more selected from the group consisting of copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0051] The thickness of the gas barrier layer 120 can be 30 μm to 100 μm, specifically 30 μm to 90 μm, and more specifically 40 μm to 80 μm. When the thickness of the gas barrier layer 120 satisfies this range, excellent moldability and gas barrier performance are achieved when the cup portion is formed.

[0052] (3) Sealant layer The sealant layer 130 is intended to completely seal the inside of the pouch-type battery case by being thermally bonded to each other at the seal portion when the pouch-type battery case accommodating the electrode assembly inside is sealed. For this purpose, the sealant layer 130 may be made of a material having excellent thermal adhesive strength.

[0053] The sealant layer 130 may be formed of a material having insulating properties, corrosion resistance, 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 properties and corrosion resistance. Furthermore, since the sealant layer 130 must completely seal the interior of the pouch-type battery case and prevent the transfer of materials between the inside and outside, it may be formed of a material having high sealing properties (e.g., excellent thermal adhesive strength). To ensure such insulating properties, corrosion resistance, and sealing properties, the sealant layer 130 may be formed of a polymer material.

[0054] The sealant layer 130 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, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon®, and glass fiber, and is preferably made of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may be cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene terpolymer.

[0055] The thickness of the sealant layer 130 can be 30 μm to 130 μm, specifically 50 μm to 120 μm, and more specifically 70 μm to 100 μm. When the thickness of the sealant layer satisfies the above range, it is possible to ensure the seal strength of the sealed portion and the formability of the pouch film laminate.

[0056] Meanwhile, the sealant layer 130 according to the present invention may have a single film structure made of any one material. Alternatively, the sealant layer 130 may have a composite film structure formed by layers of two or more materials. Specifically, the sealant layer 130 may include a first sealant layer and a second sealant layer. In this case, the first sealant layer may be a layer disposed adjacent to the gas barrier layer, and the second sealant layer may be a layer disposed on the first sealant layer. The first sealant layer and the second sealant layer may be made of materials having different materials and / or physical properties. An interface may exist between the first sealant layer and the second sealant layer. This means that the first sealant layer and the second sealant layer are different layers and may be formed separately.

[0057] In order to ensure long-term adhesion between the gas barrier layer and the first sealant layer, it is particularly preferable that the first sealant layer is made of acid-modified polypropylene (PPa), which may be maleic anhydride polypropylene (MAH PP).

[0058] The second sealant layer may be formed of a material having insulating, corrosion-resistant, and sealing properties. Specifically, since the second sealant layer is in direct contact with the electrode assembly (260 in FIG. 2) and / or the electrolyte inside the receiving space (224 in FIG. 2), it may be formed of a material having insulating and corrosion-resistant properties. Furthermore, since the second sealant layer must completely seal the interior of the battery case and prevent the transfer of materials between the interior and exterior, it may be formed of a material having high sealing properties. To ensure such insulating, corrosion-resistant, and sealing properties, the second sealant layer 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, polyparaphenylene benzobisoxazole, 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 unstretched 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), which has heat sealability and high tensile strength.

[0059] Pouch-type secondary battery Next, the pouch-type secondary battery according to the present invention will be described.

[0060] The pouch-type secondary battery according to the present invention includes a pouch-type battery case manufactured by molding the above-mentioned pouch film laminate, and an electrode assembly housed in the pouch-type battery case. Specifically, the pouch-type secondary battery according to the present invention includes a pouch-type battery case housing an electrode assembly, the pouch-type battery case being manufactured by molding a pouch film laminate, and the pouch film laminate including a first substrate layer, a second substrate layer, a gas barrier layer, and a sealant layer laminated in that order, and the moisture content index of the second substrate layer, as represented by the following formula 1, is 17,000 ppm g / cm 3 The following is the result.

[0061] [Formula 1] Moisture content index of the second base layer = Moisture content per unit weight of the pouch film laminate (ppm) × Density of the pouch film laminate (g / cm 3 ) × thickness of pouch film laminate (μm) / thickness of second base layer (μm)

[0062] Hereinafter, each component of the pouch-type secondary battery of the present invention will be described in more detail with reference to FIG.

[0063] 2 is an exploded view of a pouch-type secondary battery 200 according to the present invention. As shown in FIG. 2, the pouch-type secondary battery 200 according to the present invention may include a pouch-type battery case 210, an electrode assembly 260, an electrode lead 280, an insulating portion 290, and an electrolyte (not shown).

[0064] (1) Pouch-type battery case The pouch-type battery case 210 can be manufactured by molding the pouch film laminate of the present invention. The pouch-type battery case 210 can house the electrode assembly 260 inside. The detailed structure and properties of the pouch film laminate are as described above, and a detailed description thereof will be omitted.

[0065] The pouch film laminate may be drawn and stretched using a punch or the like to manufacture the pouch-type battery case 210. As a result, the pouch-type battery case 210 may include a cup portion 222 and a receiving portion 224. The receiving portion 224 is a portion that receives the electrode assembly, and may refer to a bag-shaped receiving space formed inside the cup portion 222 as the cup portion 222 is formed.

[0066] 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 shown in Fig. 2. The first case 220 includes a receiving portion 224 that can receive the electrode assembly 260, and the second case 230 may cover the receiving portion 224 from above to prevent the electrode assembly 260 from falling out of the battery case 210. The first case 220 and the second case 230 may be manufactured with one side connected to each other as shown in Fig. 2, but are not limited to this and may be manufactured in various ways, such as being separately manufactured.

[0067] According to another embodiment of the present invention, when forming cup portions in a pouch film laminate, two symmetrical cup portions 222, 232 may be formed adjacent to each other by drawing one pouch film laminate. In this case, as shown in FIG. 2, the first case 220 and the second case 230 may be formed with the cup portions 222, 232, respectively. After the electrode assembly 260 is accommodated in the accommodating portion 224 of the cup portion 222 of the first case 220, the bridge portion 240 formed between the two cup portions 222, 232 may 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 may accommodate the electrode assembly 260 from above. Therefore, since two cup portions 222, 232 accommodate one electrode assembly 260, an electrode assembly 260 that is thicker than when there is only one cup portion 222 can be accommodated. In addition, folding the pouch-type battery case 210 forms one edge of the secondary battery 200, which reduces the number of edges to be sealed during the subsequent sealing process, thereby improving the processing speed of the pouch-type secondary battery 200 and reducing the number of sealing processes.

[0068] The pouch-type battery case 210 may be sealed with the electrode assembly 260 housed therein so that a portion of the electrode lead 280, i.e., a terminal portion, described below, is exposed. Specifically, after the electrode lead 280 is connected to the electrode tab 270 of the electrode assembly 260 and an insulating portion 290 is formed on a portion of the electrode lead 280, the electrode assembly 260 may be housed in the housing portion 224 provided in the cup portion 222 of the first case 220, and the second case 230 may cover the housing portion 224 from above. Next, an electrolyte may be injected into the housing portion 224, and the sealing portion 250 formed on the periphery of the first case 220 and the second case 230 may be sealed.

[0069] The sealing portion 250 may serve to seal the receiving portion 224. Specifically, the sealing portion 250 may be formed along the periphery of the receiving portion 224 to seal the receiving portion 224. The temperature at which the sealing portion 250 is sealed may be 180°C to 250°C, specifically 200°C to 250°C, and more specifically 210°C to 240°C. When the sealing temperature is within this range, the pouch-type battery case 210 can ensure sufficient seal strength through thermal bonding.

[0070] (2) Electrode assembly The electrode assembly 260 can be inserted into the pouch-type battery case 210 and sealed by the pouch-type battery case 210 after the electrolyte is injected.

[0071] The electrode assembly 260 may be formed by sequentially stacking a positive electrode, a separator, and a negative electrode. Specifically, the electrode assembly 260 may include two electrodes, a positive electrode and a negative electrode, and a separator interposed between the electrodes to insulate the electrodes from each other.

[0072] 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. The slurry may be formed by stirring a granular active material, auxiliary conductor, binder, conductive material, etc., in a solvent. The solvent may be removed in a subsequent process.

[0073] A slurry containing a mixture of 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, which are then stacked on both sides of a separator to manufacture a predetermined shape of the electrode assembly 260. The electrode assembly 260 may be of a stack type, a jelly roll type, a stack and folding type, or the like, but is not limited thereto.

[0074] The electrode assembly 260 may include an electrode tab 270 .

[0075] The electrode tabs 270 are connected to the positive and negative electrodes of the electrode assembly 260, respectively, and protrude from the electrode assembly 260 to serve as paths for electrons to move between the inside and outside of the electrode assembly 260. The electrode current collector included in the electrode assembly 260 may be composed of a portion coated with an electrode active material and an end portion, i.e., a plain portion, where the electrode active material is not coated. The electrode tabs 270 may be formed by cutting the plain portion or by connecting a separate conductive member to the plain portion by ultrasonic welding, for example. As shown in FIG. 2, the electrode tabs 270 may protrude in different directions from the electrode assembly 260, but are not limited thereto. They may protrude in various directions, such as protruding in parallel from one side in the same direction.

[0076] (3) Electrode lead The electrode lead 280 may supply electricity to the outside of the secondary battery 200. The electrode lead 280 may be connected to the electrode tab 270 of the electrode assembly 260 by spot welding or the like.

[0077] 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 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.

[0078] The electrode lead 280 may include a positive electrode lead 282 having one end connected to the positive electrode tab 272 and extending in the direction in which the positive electrode tab 272 protrudes, and a negative electrode lead 284 having one end connected to the negative electrode tab 274 and extending in the direction in which the negative electrode tab 274 protrudes. The other ends of the positive electrode lead 282 and the negative electrode lead 284 may protrude to the outside of the battery case 210. This allows electricity generated inside the electrode assembly 260 to be supplied to the outside. In addition, since the positive electrode tab 272 and the negative electrode tab 274 protrude in different directions, the positive electrode lead 282 and the negative electrode lead 284 may also extend in different directions. The positive electrode lead 282 and the negative electrode 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 current collector, and the negative electrode lead 284 may be made of the same copper (Cu) material as the negative electrode current collector or a copper material coated with nickel (Ni). A portion of the electrode lead 280 protruding outside the battery case 210 serves as a terminal portion and may be electrically connected to an external terminal.

[0079] (4) Insulation section The insulating portion 290 prevents electricity generated from the electrode assembly 260 from flowing to the battery case 210 via the electrode lead 280, thereby maintaining the seal of the battery case 210. To this end, the insulating portion 290 may be formed of an insulator having low electrical conductivity. Generally, the insulating portion 290 is formed of a relatively thin insulating tape or film that is easily attached to the electrode lead 280, but is not limited thereto, and any material that can insulate the electrode lead 280 may be used.

[0080] The insulating part 290 may be disposed to surround the outer circumferential surface of the electrode lead 280. Specifically, at least a portion of the electrode lead 280 may be surrounded by the insulating part 290. In this case, the insulating part 290 may be disposed between the electrode lead 280 and the pouch-type battery case 210. The insulating part 290 may be located only in the seal part 250 where the first case 220 and the second case 230 of the pouch-type battery case 210 are thermally sealed, and may bond the electrode lead 280 to the battery case 210.

[0081] (5) Electrolyte 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 is used to move lithium ions generated by an electrochemical reaction of the electrodes during charging / discharging of the secondary battery 200, and may include a non-aqueous organic electrolyte solution 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 sulfide-based, oxide-based, or polymer-based solid electrolyte, and such a solid electrolyte may have flexibility that makes it easily deformable under external force.

[0082] The present invention will be described in more detail below with reference to specific examples. However, the following examples are merely illustrative and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope and technical concept of the present description, and it goes without saying that such changes and modifications are within the scope of the appended claims.

[0083] Examples and Comparative Examples Example 1: Manufacturing of a pouch film laminate On one side of an aluminum alloy thin film measuring 266 mm wide, 50 mm long, and 60 μm thick, a first adhesive film measuring 266 mm wide, 50 mm long, and 3 μm thick, a nylon film measuring 266 mm wide, 50 mm long, and 25 μm thick, a second adhesive film measuring 266 mm wide, 50 mm long, and 3 μm thick, and a polyethylene terephthalate (PET) film measuring 266 mm wide, 50 mm long, and 12 μm thick were laminated in this order. On the other side of the aluminum alloy thin film, a polypropylene (PP) film measuring 266 mm wide, 50 mm long, and 80 μm thick was laminated. As a result, a pouch film laminate was produced with a structure in which polypropylene film / aluminum alloy thin film / first adhesive film / nylon film / second adhesive film / polyethylene terephthalate film were laminated in this order.

[0084] Here, the polypropylene film is a sealant layer, the aluminum alloy thin film is a gas barrier layer, and the first adhesive film, nylon film, second adhesive film and polyethylene terephthalate film are base layers.

[0085] The pouch film laminate manufactured by the above method was stored in a chamber, and the moisture content per unit weight of the pouch film laminate was controlled by adjusting the moisture content in the air in the chamber.

[0086] Example 2: Manufacturing of a pouch film laminate A pouch film laminate was produced in the same manner as in Example 1.

[0087] Here, the moisture content per unit weight of the pouch film laminate was changed by adjusting the amount of moisture in the air in the chamber in which the pouch film laminate was stored.

[0088] Example 3: Preparation of a pouch film laminate A pouch film laminate was produced in the same manner as in Example 1.

[0089] Here, the moisture content per unit weight of the pouch film laminate was changed by adjusting the amount of moisture in the air in the chamber in which the pouch film laminate was stored.

[0090] Example 4: Preparation of a pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that a 40 μm thick aluminum alloy thin film and a 15 μm thick nylon film were used.

[0091] Here, the moisture content per unit weight of the pouch film laminate was changed by adjusting the amount of moisture in the air in the chamber in which the pouch film laminate was stored.

[0092] Example 5: Preparation of a pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that a 40 μm thick aluminum alloy thin film and a 15 μm thick nylon film were used.

[0093] Here, the moisture content per unit weight of the pouch film laminate was changed by adjusting the amount of moisture in the air in the chamber in which the pouch film laminate was stored.

[0094] Comparative Example 1: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1.

[0095] Here, the moisture content per unit weight of the pouch film laminate was changed by adjusting the amount of moisture in the air in the chamber in which the pouch film laminate was stored.

[0096] Comparative Example 2: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1.

[0097] Here, the moisture content per unit weight of the pouch film laminate was changed by adjusting the amount of moisture in the air in the chamber in which the pouch film laminate was stored.

[0098] Comparative Example 3: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1.

[0099] Here, the moisture content per unit weight of the pouch film laminate was changed by adjusting the amount of moisture in the air in the chamber in which the pouch film laminate was stored.

[0100] Comparative Example 4: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that a 40 μm thick aluminum alloy thin film and a 15 μm thick nylon film were used.

[0101] Here, the moisture content per unit weight of the pouch film laminate was changed by adjusting the amount of moisture in the air in the chamber in which the pouch film laminate was stored.

[0102] Comparative Example 5: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that a 40 μm thick aluminum alloy thin film and a 15 μm thick nylon film were used.

[0103] Here, the moisture content per unit weight of the pouch film laminate was changed by adjusting the amount of moisture in the air in the chamber in which the pouch film laminate was stored.

[0104] Comparative Example 6: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that a 40 μm thick aluminum alloy thin film and a 15 μm thick nylon film were used.

[0105] Here, the moisture content per unit weight of the pouch film laminate was changed by adjusting the amount of moisture in the air in the chamber in which the pouch film laminate was stored.

[0106] Experimental Example 1: Measurement of moisture content per unit weight of pouch film laminate and evaluation of moisture content index of second substrate layer The moisture content per unit weight of the pouch film laminates prepared in Examples 1 to 5 and Comparative Examples 1 to 6 was measured. Specifically, the pouch film laminates were cut into pieces measuring 50 mm x 40 mm, and the weight of moisture (μg / g = ppm) contained in the pouch film laminate per unit weight of the pouch film laminate was measured at 150°C using a Karl Fischer moisture meter.

[0107] Furthermore, the moisture content index of the second base layer was calculated from the moisture content per unit weight of the pouch film laminate and the density of the pouch film laminate according to the following formula 1, and is shown in Table 1 below.

[0108] [Formula 1] Moisture content index of the second base layer = Moisture content per unit weight of the pouch film laminate (ppm) × Density of the pouch film laminate (g / cm 3 ) × thickness of pouch film laminate (μm) / thickness of second base layer (μm)

[0109] [Table 1]

[0110] Experimental example 2: Evaluation of seal deformation Three pouch film laminates were prepared for each of Examples 1 to 5 and Comparative Examples 1 to 6. Each pouch film laminate was then cut to a size of 266 mm wide and 200 mm long, and then folded in half to a size of 133 mm wide x 200 mm long so that the sealant layers were in contact. The edges of the long sides (200 mm) were then sealed under the following three conditions to produce pouch-type battery cases.

[0111] - Seal bar area 200mm x 8mm, seal for 1.8 seconds at 210℃ and surface pressure 1.2MPa - Seal bar area 200mm x 8mm, seal for 1.8 seconds at 220℃ and surface pressure 1.0MPa - Seal bar area 200mm x 8mm, seal for 1.8 seconds at 230℃ and surface pressure 0.9MPa

[0112] Next, for each pouch-type battery case sealed at different temperatures, we visually checked whether the seal had deformed due to the generation of bubbles in the second base material layer located at the seal. The results are shown in Table 2 below.

[0113] ○: The seal is deformed due to the generation of bubbles. ×: No bubbles are generated and the seal is not deformed.

[0114] [Table 2]

[0115] According to Tables 1 and 2, the moisture content index of the second substrate layer is 17,000 ppm·g / cm 3 In the case of Examples 1 to 5 below, unlike Comparative Examples 1 to 6, it can be confirmed that even when sealed at a temperature of 220°C, no air bubbles are generated in the second base material layer and the sealed portion of the pouch-type battery case does not deform.

[0116] In addition, the moisture content index of the second base layer is 16,000 ppm g / cm 3 In the following Examples 1, 2, and 4, it was confirmed that even when sealing was performed at a temperature of 230°C, no air bubbles were generated in the second base material layer, and the sealed portion of the pouch-type battery case did not deform. [Explanation of symbols]

[0117] 100 Pouch film laminate 110 Base material layer 112 1st base layer 114 Second base layer 120 Gas barrier layer 130 Sealant Layer 200 Pouch-type secondary battery 210 Pouch-type case 220 Case 1 222 Cup section 224 Storage Unit 230 Case 2 232 Cup section 240 Bridge section 250 Seal part 260 Electrode assembly 270 Electrode Tab 272 Positive electrode tab 274 Negative electrode tab 280 Electrode Lead 282 Positive lead 284 Negative lead 290 Insulation

Claims

1. The laminated film includes a first substrate layer, a second substrate layer, a gas barrier layer, and a sealant layer, which are laminated in this order; The moisture content index of the second base layer represented by the following formula 1 is 17,000 ppm g / cm ３ A pouch film laminate, which is: [Formula 1] Moisture content index of second base layer = moisture content per unit weight of pouch film laminate (ppm) × density of pouch film laminate (g / cm ３ ) × thickness of pouch film laminate (μm) / thickness of second base layer (μm)

2. The pouch film laminate according to claim 1, wherein the moisture content per unit weight of the pouch film laminate is 1,500 ppm or less.

3. The pouch film laminate according to claim 1, wherein the thickness of the first base layer is 10 μm to 50 μm.

4. The pouch film laminate according to claim 1 , wherein the first base layer comprises a polyester-based film.

5. The pouch film laminate according to claim 1 , wherein the first base layer comprises at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

6. The pouch film laminate according to claim 1, wherein the second base layer has a thickness of 10 μm to 50 μm.

7. The pouch film laminate according to claim 1 , wherein the second substrate layer comprises a polyamide-based film.

8. 2. The pouch film laminate according to claim 1, wherein the second substrate layer comprises 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.

9. The pouch film laminate according to claim 1 , wherein the melting temperature of the second base material layer is 220° C. or higher.

10. 2. The pouch film laminate according to claim 1, wherein the gas barrier layer has a thickness of 30 μm to 100 μm.

11. The pouch film laminate according to claim 1 , wherein the gas barrier layer comprises aluminum.

12. 2. The pouch film laminate according to claim 1, wherein the sealant layer has a thickness of 30 μm to 130 μm.

13. A pouch-type battery case manufactured by molding the pouch film laminate according to any one of claims 1 to 12.

14. A pouch-type battery case manufactured by molding the pouch film laminate according to any one of claims 1 to 12; and an electrode assembly housed in the pouch-type battery case.

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