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 material layer, a second base material layer, a gas barrier layer, and a sealant layer laminated in this order, wherein the moisture content per unit weight of the pouch film laminate is 1,000 ppm or more, the melting temperature of the second base material layer is 240°C or more, and the thickness of the gas barrier layer is 45 μm to 100 μm.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0015126 filed on February 3, 2023, and Korean Patent Application No. 10-2024-0009781 filed on January 22, 2024, and all contents disclosed in the documents of said Korean patent applications 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 electricity 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, which is made up of alternately stacked positive and negative electrodes and separators interposed between them, in a battery case, injecting an electrolyte, and then sealing the battery case. Secondary batteries are 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 increased. To manufacture pouches with excellent moldability, a thick gas barrier layer is formed, but this results in the sealant layer not easily melting during the sealing of the pouch-type battery case. To address this issue, methods of applying more heat during the sealing of pouch-type battery cases have been used, such as increasing the sealing temperature and / or sealing time. However, increasing the sealing temperature above 235°C causes deformation due to melting of the base layer, and extending the sealing time increases the production time (tact time), resulting in reduced productivity. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made to solve the above problems, and provides a pouch film laminate that can ensure both sealing quality and processability by preventing deformation of the seal portion and shortening the sealing time during the process of sealing a pouch-type battery case manufactured from the pouch film laminate. [Means for solving the problem]

[0008] One embodiment of the present invention provides a pouch film laminate including a first base material layer, a second base material layer, a gas barrier layer, and a sealant layer laminated in that order, wherein the moisture content per unit weight of the pouch film laminate is 1,000 ppm or more, the melting temperature of the second base material layer is 240°C or more, and the thickness of the gas barrier layer is 45 μm to 100 μm.

[0009] The moisture content per unit weight of the pouch film laminate can be 1,000 ppm to 7,000 ppm.

[0010] The melting temperature of the first base layer may be 250°C or higher. The thickness of the first base layer may be 10 μm to 50 μm. The first base layer may include a polyester film. Specifically, the first base layer may include at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

[0011] The thickness of the second base layer may be 10 μm to 50 μm. The second base layer may include a polyamide film. Specifically, the second base layer may include at least one selected from the group consisting of nylon 6,6, nylon MXD6 (polyxylylene adipamide), nylon 4, nylon 4,6, and nylon 4,10.

[0012] The thickness of the gas barrier layer can be from 60 μm to 80 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] In another embodiment of the present invention, there is provided a pouch-type battery case manufactured by molding the above-mentioned pouch film laminate.

[0016] In 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 conventional pouch film laminates, even if the first substrate layer attempts to prevent moisture penetration 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, in the case of pouch-type battery cases manufactured by molding conventional pouch film laminates, when the case is sealed at high temperatures to provide sufficient heat within the required production time, the moisture absorbed in the second substrate layer within the pouch film laminate evaporates, causing bubbles to form in the second substrate layer. This causes deformation and damage to the seal, resulting in a decrease in the insulating properties of the pouch.

[0018] To solve these problems, pouch-type battery cases manufactured from conventional pouch film laminates are sealed at low temperatures, which increases the sealing time and reduces the efficiency of the production process.Furthermore, to solve these problems, reducing the moisture content per unit weight of the pouch film laminate to less than 1,000 ppm requires difficult and expensive storage management of the pouch film laminate after production.

[0019] To solve the above-mentioned problems, the present invention incorporates a second base material layer having a gas barrier layer thickness of 45 μm to 100 μm and a melting temperature of 240°C or higher into a pouch film laminate having a moisture content per unit weight of 1,000 ppm or higher. This makes it possible to suppress the generation of bubbles due to evaporation of moisture in the second base material layer, even when a pouch battery case manufactured from the pouch film laminate is sealed at a temperature of 235°C or higher. As a result, deformation of the seal of the pouch battery case is prevented, and the sealing time can be shortened, ensuring the sealing quality and processability of the pouch battery case, and improving the durability and life characteristics of the pouch secondary battery.

[0020] Furthermore, when a pouch-type battery case is manufactured using the pouch film laminate of the present invention, a separate process for reducing the moisture content per unit weight of the pouch film laminate to less than 1,000 ppm is not required, thereby improving the efficiency of the manufacturing process and reducing manufacturing costs. [Brief explanation of the drawings]

[0021] 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, but the present invention should not be interpreted as being limited solely to the matters depicted in such drawings.

[0022] [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

[0023] The advantages and features of the present invention, as well as methods for achieving them, will become clearer with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be realized in various different forms. However, the present embodiments are provided to provide a complete disclosure of the present invention and to enable those skilled in the art to fully understand the scope of the invention, and the present invention is defined solely by the claims. The same reference symbols refer to the same elements throughout the specification.

[0024] Unless otherwise specified, 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 should not be interpreted ideally or excessively unless otherwise clearly defined.

[0025] The terms used in this specification are for the purpose of describing the embodiments and are not intended to limit the present invention. In this specification, the singular form includes the plural form unless otherwise stated in the text. The terms "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.

[0026] In this specification, when a part is said to include a certain component, this does not mean that it excludes other components, but that it may further include other components, unless otherwise specified to the contrary.

[0027] In this specification, the phrase "A and / or B" means A, or B, or A and B.

[0028] In this specification, "%" means % by weight unless expressly indicated otherwise.

[0029] 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) at 150°C using a Karl Fischer moisture meter.

[0030] Pouch film laminate The pouch film laminate according to the present invention comprises a first base material layer, a second base material layer, a gas barrier layer, and a sealant layer laminated in that order, and has a moisture content per unit weight of 1,000 ppm or more, a melting temperature of the second base material layer of 240°C or more, and a thickness of the gas barrier layer of 45 μm to 100 μm.

[0031] The moisture content per unit weight of the pouch film laminate according to the present invention may be 1,000 ppm or more, specifically 1,000 ppm to 7,000 ppm, and more specifically 1,000 ppm to 3,000 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). In the present invention, 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.

[0032] In general, when conventional pouch film laminates with a moisture content per unit weight within the above range are sealed at temperatures above 235°C to provide sufficient heat within the required production time during the manufacturing process of a pouch-type battery case from the pouch film laminate, the moisture contained in the second substrate layer evaporates, causing bubbles to form in the second substrate layer. The formation of bubbles in the second substrate layer can cause deformation and damage to the seal, resulting in a reduction in the insulating properties of the pouch. To avoid this problem, reducing the moisture content per unit weight of the pouch film laminate to less than 1,000 ppm requires a separate post-processing step during the manufacturing process of the pouch film laminate, which is costly.

[0033] However, since the pouch film laminate according to the present invention includes a gas barrier layer having a thickness of 45 μm to 100 μm and a second base material layer having a melting temperature of 240°C or higher, even if the moisture content per unit weight of the pouch film laminate is 1,000 ppm or higher, the generation of bubbles due to evaporation of moisture in the base material layer can be suppressed when a pouch-type battery case manufactured from the pouch film laminate is sealed at a temperature of 235°C or higher.

[0034] The thickness of the gas barrier layer 120 included in the pouch film laminate according to the present invention is 45 μm to 100 μm. The thickness of the gas barrier layer 120 can be specifically 50 μm to 90 μm, more specifically 60 μm to 80 μm. If the thickness of the gas barrier layer 120 is less than 45 μm, moldability during cup molding decreases. Furthermore, when the seal portion is sealed for the same time and at the same temperature, heat loss from the second substrate layer 114 to the gas barrier layer 120 decreases, causing a rapid rise in the temperature of the second substrate layer 114, resulting in the generation of bubbles in the second substrate layer 114 and a decrease in the mechanical strength of the pouch film laminate. If the thickness of the gas barrier layer exceeds 100 μm, the yield strength of the pouch film laminate increases, causing the pouch film laminate to slip easily from the mold during molding, resulting in wrinkles. Furthermore, if the gas barrier layer 120 is excessively thick, heat loss to the gas barrier layer 120 increases, and heat is not sufficiently transferred to the sealant layer 130, resulting in a decrease in hermetic sealing performance. Therefore, when the thickness satisfies the above range, excellent formability during cup formation can be achieved, the mechanical strength of the pouch film laminate can be increased, and deformation and damage to the seal portion can be prevented, thereby improving the insulation properties of the pouch. Another feature of the present invention is that a rapid increase in temperature of the second base layer 114 is prevented, preventing the generation of bubbles, and heat is sufficiently transferred to the sealant layer 130, achieving excellent hermetic sealing performance. Therefore, it is preferable to satisfy the above thickness of the gas barrier layer 120 in terms of achieving excellent insulation, processability, and hermetic sealing performance.

[0035] 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.

[0036] (1) Base material layer The substrate layer 110 is formed as the outermost layer of the pouch film laminate 100 and protects 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.

[0037] 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 does not increase, and the energy density per volume of the secondary battery can be increased.

[0038] 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.

[0039] 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 having different materials 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.

[0040] The first base material layer 112 and the second base material layer 114 will now be described in more detail.

[0041] 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.

[0042] 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 to this.

[0043] 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 insulation 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 does not increase, and the energy density per volume of the secondary battery is increased.

[0044] The melting temperature of the first base layer 112 may be 250° C. or higher, specifically 250° C. to 350° C., and more specifically 250° C. to 300° C. If the temperature of the first base layer 112 falls within this range, thermal deformation and damage to the first base layer can be minimized when sealing is performed at a high temperature of 235° C. or higher.

[0045] 2) Second base material layer As described above, the second substrate layer 114 may be a layer disposed between the first substrate layer 112 and the gas barrier layer 120. In this case, the second substrate layer 114 may serve to improve the formability of the pouch.

[0046] The melting temperature of the second base layer 114 according to the present invention may be 240°C or higher, specifically 240°C to 350°C, and more specifically 240°C to 300°C. In the pouch film laminate according to the present invention, which has a moisture content per unit weight of 1,000 ppm or higher, if the melting temperature of the second base layer 114 is lower than 240°C, there is a problem that when sealing is performed at a temperature of 235°C or higher to supply a sufficient amount of heat within a predetermined required production time, the moisture contained in the second base layer evaporates, causing deformation and damage to the sealed portion. There is also a problem that when sealing is performed at a temperature of lower than 235°C, the sealing time increases, reducing the efficiency of the production process.

[0047] The second base layer 114 may include a polyamide-based film. For example, the second base layer 114 may include at least one selected from the group consisting of nylon 6,6, nylon-MXD6 (polyxylylene adipamide), nylon 4, nylon 4,6, and nylon 4,10, but is not limited to this. Preferably, since the second base layer 114 has a melting temperature of 240°C or higher, the second base layer 114 may include nylon 6,6 and / or nylon-MXD6, and may not include nylon 6, nylon 6,10, nylon 6,12, nylon 10,10, nylon 11, and / or nylon 11,12.

[0048] 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.

[0049] The second substrate layer 114 may contain metal oxide particles. The metal oxide particles are hydroxylated by reacting with moisture that flows 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.

[0050] The second base layer 114 may further include an additive. The inclusion of an additive in the second base layer 114 can 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.

[0051] (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.

[0052] 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.

[0053] In 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).

[0054] As another example, the gas barrier layer 120 can be formed of a stainless steel thin film. Specifically, the gas barrier layer 120 can be manufactured by molding and / or processing the stainless steel thin film. The gas barrier layer 120 formed 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 suppress the occurrence of cracks 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).

[0055] (3) Sealant layer When the pouch-type battery case accommodating the electrode assembly therein is sealed, the sealant layer 130 is thermally bonded to each other at the seal portion to completely seal the inside of the pouch-type battery case. For this reason, the sealant layer 130 may be formed of a material with excellent thermal adhesive strength.

[0056] 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 to prevent the transfer of substances 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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).

[0061] 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 electrolyte inside the storage 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 inside and outside, 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 can be composed of unstretched polypropylene, acid-modified polypropylene, polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene terpolymer. Here, the acid-modified polypropylene can be maleic anhydride polypropylene (MAH PP). More preferably, the second sealant layer can be cast polypropylene (CPP), which has heat-sealability and high tensile strength.

[0062] Pouch-type secondary battery Next, the pouch-type secondary battery according to the present invention will be described.

[0063] 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, 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, the moisture content per unit weight being 1,000 ppm or more, and the melting temperature of the second substrate layer being 240°C or higher.

[0064] Hereinafter, each component of the pouch-type secondary battery of the present invention will be described in more detail with reference to FIG.

[0065] 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).

[0066] (1) Pouch-type battery case The pouch-shaped battery case 210 can be manufactured by molding the pouch film laminate of the present invention described above. The pouch-shaped battery case 210 can house the electrode assembly 260 inside. The detailed structure and physical properties of the pouch film laminate are as described above, so a detailed description will be omitted.

[0067] 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 have 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 when the cup portion 222 is formed.

[0068] In one embodiment of the present invention, the pouch-type battery case 210 may have 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 can 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 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.

[0069] In 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 cup portions 222, 232, respectively. After the electrode assembly 260 is housed in the housing 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 house the electrode assembly 260 from above. Therefore, since two cup portions 222, 232 house one electrode assembly 260, a thicker electrode assembly 260 can be housed than if there were only one cup portion 222. Furthermore, by folding the pouch-type battery case 210, one end of the secondary battery 200 is formed, and the number of ends to be sealed in the subsequent sealing process can be reduced, thereby improving the processing speed of the pouch-type secondary battery 200 and reducing the number of sealing processes.

[0070] The pouch-type battery case 210 can 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, when the electrode lead 280 is connected to the electrode tab 270 of the electrode assembly 260 and an insulating portion 290 is formed on a portion of the electrode lead 280, the electrode assembly 260 can be housed in the housing portion 224 provided in the cup portion 222 of the first case 220, and the second case 230 can cover the housing portion 224 from above. Next, an electrolyte is injected into the housing portion 224, and the seal portion 250 formed on the periphery of the first case 220 and the second case 230 can be sealed.

[0071] 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.

[0072] (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.

[0073] 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 types of electrodes, a positive electrode and a negative electrode, and a separator interposed between the electrodes to insulate them from each other.

[0074] 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 is typically formed by stirring a granular active material, auxiliary conductor, binder, and conductive material in a solvent. The solvent can be removed in a subsequent process.

[0075] 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.

[0076] The electrode assembly 260 may include an electrode tab 270 .

[0077] 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 form a path 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 not coated with the electrode active material, i.e., a plain portion. 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, etc. 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 parallel to one side in the same direction.

[0078] (3) Electrode lead The electrode lead 280 can supply electricity to the outside of the secondary battery 200. The electrode lead 280 can be connected to the electrode tab 270 of the electrode assembly 260 by spot welding or the like.

[0079] The electrode lead 280 is connected to the electrode assembly 260 and can protrude to the outside of the pouch-type battery case 210 through 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 can protrude to the outside of the pouch-type battery case 210.

[0080] 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 271 and extending in the direction in which the negative electrode tab 271 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 271 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 can be electrically connected to an external terminal.

[0081] (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 that is electrically non-conductive and does not easily allow electricity to pass through. 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.

[0082] The insulating part 290 may be disposed to cover 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 disposed 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 the electrode lead 280 may be bonded to the battery case 210.

[0083] (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 migrates lithium ions generated by an electrochemical reaction of the electrodes during charge / discharge 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.

[0084] The present invention will be described in more detail below with reference to specific examples. However, the following examples are merely illustrative to aid in understanding the present invention 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 fall within the scope of the appended claims.

[0085] 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-MXD6 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. A polypropylene (PP) film measuring 266 mm wide, 50 mm long, and 80 μm thick was coextruded on the other side of the aluminum alloy thin film. As a result, a pouch film laminate was produced with a structure in which polypropylene film / aluminum alloy thin film / first adhesive film / Nylon-MXD6 film / second adhesive film / polyethylene terephthalate film were laminated in this order.

[0086] 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.

[0087] 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.

[0088] Example 2: Manufacturing of a pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that an aluminum alloy thin film having a thickness of 80 μm was used.

[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 3: Preparation of a pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that an 80 μm thick aluminum alloy thin film and a 30 μm thick nylon 6,6 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] Comparative Example 1: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that a nylon 6 film was used instead of the nylon MXD6 film.

[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 2: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that an 80 μm thick aluminum alloy thin film was used and a 25 μm thick nylon 6 film was used instead of the nylon MXD6 film.

[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 3: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that an 80 μm thick aluminum alloy thin film and a 30 μm thick nylon 6,6 film were used.

[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 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 MXD6 film were used.

[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] Experimental Example 1: Measurement of moisture content per unit weight of pouch film laminate The moisture content per unit weight of the pouch film laminates produced in Examples 1 to 3 and Comparative Examples 1 to 4 was measured. Specifically, the pouch film laminates were cut into pieces measuring 50 mm x 40 mm, and the amount 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. The measurement results are shown in Table 1 below.

[0101] Experimental example 2: Evaluation of appearance deformation of the seal Six pouch film laminates were prepared for each of Examples 1 to 3 and Comparative Examples 1 to 4. 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 six conditions to produce pouch-type battery cases.

[0102] -Seal bar area 200mm x 8mm, 210℃, surface pressure 1.2MPa, seal for 1.8 seconds -Seal bar area 200mm x 8mm, 220℃, surface pressure 1.0MPa, seal for 1.8 seconds -Seal bar area 200mm x 8mm, 230℃, surface pressure 0.9MPa, seal for 1.8 seconds -Seal bar area 200mm x 8mm, 235℃, surface pressure 0.9MPa, seal for 1.6 seconds -Seal bar area 200mm x 8mm, 240℃, surface pressure 0.9MPa, seal for 1.4 seconds -Seal bar area 200mm x 8mm, 250℃, surface pressure 0.9MPa, seal for 1.2 seconds.

[0103] Next, each pouch-type battery case sealed at different temperatures was visually inspected to see if the seal had been deformed due to bubbles generated in the second base material layer disposed in the seal. The results are shown in Table 1 below.

[0104] ○: Air bubbles cause deformation of the seal ×: No bubbles are generated and the seal portion is not deformed.

[0105] [Table 1]

[0106] According to Table 1, in Examples 1 to 3, where the moisture content per unit weight of the pouch film laminate is 1,000 ppm or more, the melting temperature of the second base layer is 240°C or more, and the thickness of the gas barrier layer is 45 μm to 100 μm, it can be seen that, unlike Comparative Examples 1 to 3, where the moisture content per unit weight of the pouch film laminate is 1,000 ppm or more, the melting temperature of the second base layer is less than 240°C, and the thickness of the gas barrier layer is 45 μm to 100 μm, no bubbles are generated in the second base layer and the seal portion of the pouch-type battery case does not deform even when sealed at temperatures of 220°C or higher.

[0107] In Comparative Example 4, the same Nylon-MXD6 film as in Examples 1 and 2 was used as the second base material layer, but the thickness of the gas barrier layer was less than 45 μm, so the heat loss of the Nylon-MXD6 film could not be sufficiently increased. As a result, when the pouch-type battery case was sealed at a temperature of 235°C or higher, air bubbles were generated in the second base material layer, and the sealed portion of the pouch-type battery case was deformed.

[0108] On the other hand, in the case of Example 3, since the melting temperature of the nylon 6,6 film contained in the second base material layer is 250°C, it can be confirmed that even when sealing is performed at a temperature condition of 240°C, no air bubbles are generated in the second base material layer and the seal portion of the pouch-type battery case does not deform. [Explanation of symbols]

[0109] 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 271 Negative electrode tab 272 Positive electrode tab 280 Electrode Lead 282 Positive lead 284 Negative lead 290 Insulation

Claims

1. A pouch film laminate comprising a first base material layer, a second base material layer, a gas barrier layer, and a sealant layer laminated in this order, The moisture content per unit weight of the pouch film laminate is 1,000 ppm or more, The melting temperature of the second base material layer is 240°C or higher, The pouch film laminate, wherein the gas barrier layer has a thickness of 45 μm to 100 μm.

2. The pouch film laminate according to claim 1, wherein the moisture content per unit weight of the pouch film laminate is 1,000 ppm to 7,000 ppm.

3. The pouch film laminate according to claim 1 , wherein the melting temperature of the first base material layer is 250° C. or higher.

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

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

6. 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.

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

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

9. The pouch film laminate according to claim 1, wherein the second substrate layer comprises at least one selected from the group consisting of nylon 6,6, nylon MXD6 (polyxylylene adipamide), nylon 4, nylon 4,6, and nylon 4,10.

10. 2. The pouch film laminate according to claim 1, wherein the gas barrier layer has a thickness of 60 μm to 80 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; an electrode assembly housed in the pouch-type battery case; A pouch-type secondary battery comprising:

Images