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 priority under Korean Patent Application No. 10-2023-0015125 dated 3 February 2023, and all content disclosed in the said Korean Patent Application is incorporated herein by reference.

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

[0003] Rechargeable batteries are used in a wide range of applications, from small products such as digital cameras, DVD players, MP3 players, mobile phones, PDAs, portable game devices, power tools, and electric bicycles (E-bikes), to large products requiring high power output, such as electric vehicles and hybrid vehicles, as well as power storage devices and backup power storage devices that store surplus generated electricity and new renewable energy. Types of rechargeable batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries.

[0004] Rechargeable batteries can be manufactured by housing an electrode assembly, in which positive electrodes, negative electrodes, and separators interposed between them are alternately stacked, in a battery case, injecting an electrolyte, and then sealing the battery case. Rechargeable batteries are classified into pouch type and can type, etc., depending on the material of the case that houses the electrode assembly.

[0005] A pouch-type secondary battery can be manufactured by press-forming a flexible pouch film laminate to form a cup portion, then housing an electrode assembly in the internal storage space of the cup portion, and finally sealing the seal portion. The pouch film laminate is formed from multiple layers, each consisting of a gas barrier layer made of metal material with a polymer film such as polyethylene terephthalate laminated on one side and a sealant layer made of thermoplastic polyolefin resin laminated on the other side. When the pouch-type battery case is sealed, the sealant layers are heat-bonded to each other, thereby forming the seal portion.

[0006] Recently, as the capacity of pouch-type secondary batteries has increased, the demand for pouches with excellent moldability has been growing. When the thickness of the gas barrier layer is increased to produce pouches with excellent moldability, there is a problem in that the sealant layer does not melt easily when sealing the pouch-type battery case. Conventionally, to solve this problem, methods such as increasing the sealing temperature and / or sealing time have been used to apply more heat when sealing the pouch-type battery case. However, when the sealing temperature is raised to 220°C or higher, the base layer melts and deforms, and when the sealing time is extended, the production time (tact time) increases and productivity decreases. [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention aims to solve the above-mentioned problems and provides a pouch film laminate that prevents deformation of the sealed portion and shortens the sealing time during the sealing process of a pouch-type battery case manufactured from a pouch film laminate, thereby ensuring both sealing quality and processability. [Means for solving the problem]

[0008] According to one embodiment of the present invention, the material comprises a first substrate layer, a second substrate layer, a gas barrier layer, and a sealant layer, which are stacked in order, and the moisture content index of the second substrate layer, represented by the following formula 1, is 17,000 ppm·g / cm³. 3 The following pouch film laminate is provided. [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 / cm³) 3 ) × Thickness of the pouch film laminate (μm) / Thickness of the second substrate 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 substrate layer can be 10 μm to 50 μm. The first substrate layer may include a polyester film. Specifically, the first substrate 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 substrate layer can 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 between 30 μm and 100 μm.

[0013] The gas barrier layer may include aluminum.

[0014] The thickness of the sealant layer can be between 30 μm and 130 μm.

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

[0016] According to another embodiment of the present invention, there is provided a pouch-type secondary battery including the 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, by setting the moisture content index of the second base material layer represented by the above formula 1 to be 17,000 ppm·g / cm 3 or less, even when the pouch-type battery case manufactured from the pouch film laminate is sealed at a temperature of 220°C or higher, it is possible to suppress the generation of bubbles due to the vaporization of moisture in the second base material layer, prevent deformation of the seal portion, and shorten the sealing time. As a result, it is possible to ensure the sealing quality and processability of the pouch-type battery case manufactured from the pouch film laminate of the present invention, and improve the durability and life characteristics of the pouch-type secondary battery.

Brief Description 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 better understand the technical idea of the present invention. The present invention should not be construed as being limited only to the matters described in such drawings.

[0019] [Figure 1] It is a cross-sectional view of the pouch film laminate according to the present invention. [Figure 2] It is an exploded perspective view of the pouch-type secondary battery according to the present invention.

Modes for Carrying Out 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 embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and can be realized in a variety of different forms. These embodiments are provided to complete the disclosure of the present invention and to fully inform those who are ordinary skill in the art to which the invention pertains, of the scope of the invention, which is defined only by the claims. Throughout the specification, the same reference numerals refer to the same components.

[0021] Unless otherwise defined, all terms used herein (including technical and scientific terms) should be used in a way that can be commonly understood by a person of ordinary skill in the art to which this invention pertains. Furthermore, terms defined in commonly used dictionaries should not be interpreted ideally or excessively unless explicitly defined otherwise.

[0022] The terms used herein are for illustrative purposes only and are not intended to limit the invention. In this specification, singular nouns include plural nouns unless otherwise specified. The terms “comprises” and / or “comprising” as used in this specification do not preclude the presence or addition of one or more other components beyond those mentioned.

[0023] In this specification, when a part is said to include a component, this means that, unless otherwise specified, it may include other components rather than excluding them.

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

[0025] In this specification, "%" means weight percent unless otherwise explicitly indicated.

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

[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, which are laminated in order, and the moisture content index of the second substrate layer, represented by the following formula 1, is 17,000 ppm·g / cm³. 3 The following applies:

[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 / cm³) 3 ) × Thickness of the pouch film laminate (μm) / Thickness of the second substrate layer (μm)

[0029] In conventional pouch film laminates, although the first substrate layer prevents moisture from penetrating from outside the pouch, due to its thickness and material limitations, moisture from outside the pouch may pass through the first substrate layer and reach the second substrate layer. In this case, the moisture can be easily 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 into the second substrate layer vaporizes, causing bubbles to form in the second substrate layer. This deforms and damages the seal portion of the pouch, leading to a decrease in the pouch's insulating properties.

[0030] The present invention solves the above-mentioned problems by reducing the moisture content of the pouch film laminate to below a predetermined level. Specifically, the pouch film laminate according to the present invention has a moisture content index of the second base material layer represented by formula 1 of 17,000 ppm·g / cm³. 3The following is the case. As a result, even when the pouch film laminate of the present invention is sealed at a high temperature, generation of bubbles due to vaporization 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 material layer represented by the formula 1 is 17,000 ppm·g / cm 3 Hereinafter, specifically, it is 1,000 ppm·g / cm 3 ~17,000 ppm·g / cm 3 More specifically, it can be 1,000 ppm·g / cm 3 ~16,000 ppm·g / cm 3 Here, the moisture content index of the second base material layer means the weight (ppm·g / cm 3 ) ) of moisture contained in the second base material layer per unit volume of the second base material layer. When the moisture content index of the second base material layer exceeds 17,000 ppm·g / cm 3 , in order to supply sufficient heat within the production required time defined in the process of sealing the pouch-type battery case manufactured from the pouch film laminate, when sealing at a temperature condition of 220 °C or higher, the moisture contained in the second base material layer vaporizes, generating bubbles in the second base material layer, and as a result, there is a problem that the insulating property of the pouch decreases due to deformation and damage of the seal portion.

[0032] The moisture content per unit weight of the pouch film laminate according to the present invention can 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 water contained in the pouch film laminate per unit weight (μg / g = ppm). When the moisture content per unit weight of the pouch film laminate satisfies the above numerical range, the moisture content contained 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 a temperature of 220°C or higher, the generation of bubbles due to the vaporization of water in the second base layer can be suppressed, and damage to the sealed portion can be prevented. On the other hand, the moisture content per unit weight of the pouch film laminate may vary depending on the amount of moisture in the air in the chamber where the pouch film laminate is stored, and / or the exposure time of the pouch film laminate to the air, but the method of controlling the moisture content is not limited to this.

[0033] On the other hand, Figure 1 is a cross-sectional view of the pouch film laminate 100 according to the present invention. Hereinafter, each component of the pouch film laminate 100 of the present invention will be described in more detail with reference to Figure 1.

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

[0035] The thickness of the base 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 layer 110 satisfies the above range, it can have excellent external insulation properties, a low overall pouch thickness, and excellent energy density relative to the volume of the secondary battery.

[0036] The substrate layer 110 according to the present invention may have a composite film structure in which two or more materials are formed in layers. In the composite film structure, adhesive layers may be further formed between each layer.

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

[0038] The first base layer 112 and the second base layer 114 described above will be explained in more detail below.

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

[0040] The first base layer 112 can 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, poly(p-phenylenebenzobisoxazole), polyarylate, Teflon®, and glass fiber. Preferably, the first base layer 112 may include a polyester-based film having abrasion resistance and heat resistance. For example, the first base layer 112 may include, but is not limited to, at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

[0041] The thickness of the first base material 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 material layer 112 satisfies the above numerical range, the insulating properties and moldability of the pouch can be ensured, and the penetration of moisture into the interior of the pouch film laminate can be effectively suppressed. Furthermore, the overall thickness of the pouch is not large, resulting in excellent energy density relative to the volume of the secondary battery.

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

[0043] The second base layer 114 may include a polyamide film. For example, the second base layer 114 may include, but is not limited to, 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. Preferably, the second base layer 114 may contain nylon 6, in which case the excellent stretchability of nylon 6 has the advantage of improving the moldability of the pouch.

[0044] The thickness of the second base material 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 material layer 114 satisfies the above numerical range, the moldability of the pouch can be ensured, and a decrease in the energy density relative to the volume of the secondary battery due to the thickness of the pouch film laminate being excessively thick can be prevented.

[0045] The second substrate layer 114 may contain metal oxide particles. Since the metal oxide particles undergo hydroxylation by reacting with moisture that flows into the second substrate layer 114, moisture in the second substrate layer 114 can be removed. The metal oxide particles may include at least one selected from the group consisting of CaO, MnO, SrO, MgO, and ZnO. Preferably, the metal oxide particles may include at least one of CaO and MgO, which are favorable for hydroxylation with moisture.

[0046] The second base layer 114 may further contain additives. By including additives in the second base layer 114, the physical properties of the second base layer 114 can be altered. For example, at least one of carbon fiber, glass fiber, and aramid fiber can 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 substrate layer 110 and the sealant layer 130 to ensure the mechanical strength of the pouch, block the entry and exit of gases or moisture from the outside of the secondary battery, and prevent electrolyte leakage from inside the pouch-type battery case.

[0048] The gas barrier layer 120 can be formed of a metal. For example, the gas barrier layer may be, but is 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 can be formed from an aluminum alloy thin film. When the gas barrier layer 120 is formed using an aluminum alloy thin film, it is possible to ensure mechanical strength above a predetermined level, and the weight is light, while complementing the electrochemical properties of the electrode assembly and electrolyte, as well as ensuring heat dissipation, etc. 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 can be formed from a stainless steel thin film. Specifically, the gas barrier layer 120 can be manufactured by molding and / or processing a stainless steel thin film. Because the gas barrier layer 120 formed from stainless steel has relatively low thermal conductivity, it is effective in preventing or delaying heat diffusion to other cells during thermal runaway, and because it has relatively high toughness, it can suppress the occurrence of cracks in the pouch during use of pouch-type batteries. Stainless steel may contain one or more elements other than iron (Fe), for example, 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 the above range, the moldability and gas barrier performance are excellent during the molding of the cup portion.

[0052] (3) Sealant layer The sealant layer 130 is designed to completely seal the inside of the pouch-type battery case by being heat-bonded to each other at the sealing portion when the pouch-type battery case, which houses the electrode assembly inside, is sealed. For this purpose, the sealant layer 130 can be formed from a material that has excellent heat bonding strength.

[0053] The sealant layer 130 can be formed from a material that has insulating, corrosion-resistant, and sealing properties. Specifically, since the sealant layer 130 is in direct contact with the electrode assembly and / or electrolyte inside the pouch-type battery case, it can be formed from a material that has insulating and corrosion-resistant properties. Furthermore, since the sealant layer 130 must completely seal the inside of the pouch-type battery case and block the movement of substances between the inside and outside, it can be formed from a material with high sealing properties (e.g., excellent thermal adhesion strength). To ensure such insulating, corrosion-resistant, and sealing properties, the sealant layer 130 can be formed from a polymer material.

[0054] The sealant layer 130 can consist of one or more substances selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyarylate, Teflon®, and glass fibers, and preferably consists of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene can consist of unoriented polypropylene (Cast Polypropylene, CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer and / or polypropylene-butylene-ethylene ternary copolymer.

[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 has the effect of ensuring the seal strength of the sealed portion and ensuring the moldability of the pouch film laminate.

[0056] On the other hand, the sealant layer 130 according to the present invention may have a single film structure made of any one of the following materials. In contrast, the sealant layer 130 may have a composite film structure formed by two or more materials each forming a layer. 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 positioned adjacent to the gas barrier layer, and the second sealant layer may be a layer positioned on the first sealant layer. The first sealant layer and the second sealant layer may each be made of materials with different properties and / or materials. 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] The first sealant layer is particularly preferably made of acid-modified polypropylene (PPa) in order to ensure long-term adhesion between the gas barrier layer and the first sealant layer. Here, the acid-modified polypropylene can be Malak anhydride polypropylene (MAH PP).

[0058] The second sealant layer can be formed from 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 Figure 2) and / or electrolyte inside the containment space (224 in Figure 2), it can be formed from a material having insulating and corrosion-resistant properties. Furthermore, since the second sealant layer must completely seal the inside of the battery case and block the movement of substances between the inside and outside, it can be formed from a material with high sealing properties. To ensure such insulating, corrosion-resistant, and sealing properties, the second sealant layer can consist 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, poly(p-phenylenebenzobisoxazole), polyarylate, Teflon®, and glass fibers. Preferably, the second sealant layer can consist of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene can consist of unoriented polypropylene, acid-modified polypropylene, polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene ternary copolymer. Here, the acid-modified polypropylene can be Malak anhydride polypropylene (MAH PP). More preferably, the second sealant layer may include unoriented polypropylene (Cast Polypropylene, CPP) which has heat-sealing properties and high tensile strength.

[0059] Pouch-type rechargeable 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 in which the electrode assembly is housed, the pouch-type battery case is manufactured by molding a pouch film laminate, the pouch film laminate includes a first substrate layer, a second substrate layer, a gas barrier layer and a sealant layer that are sequentially laminated, and the moisture content index of the second substrate layer, represented by the following formula 1, is 17,000 ppm·g / cm³. 3 The following applies:

[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 / cm³) 3 ) × Thickness of the pouch film laminate (μm) / Thickness of the second substrate layer (μm)

[0062] The components of the pouch-type secondary battery of the present invention will be described in more detail below with reference to Figure 2.

[0063] Figure 2 is an exploded assembly diagram of the pouch-type secondary battery 200 according to the present invention. As shown in Figure 2, the pouch-type secondary battery 200 of the present invention may include a pouch-type battery case 210, an electrode assembly 260, electrode leads 280, an insulating part 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 described above. The pouch-type 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, and a detailed explanation is omitted.

[0065] The pouch film laminate can be drawn and stretched by punching or the like for the manufacture of a pouch-type battery case 210. As a result, the pouch-type battery case 210 may include a cup portion 222 and a housing portion 224. The housing portion 224 is a portion for housing an electrode assembly and can mean a housing space that is formed in a bag-like shape 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 Figure 2. The first case 220 includes a housing section 224 capable of housing an electrode assembly 260, and the second case 230 can cover the housing section 224 from above to prevent the electrode assembly 260 from detaching from the battery case 210. The first case 220 and the second case 230 may be manufactured with one side connected to the other, as shown in Figure 2, but are not limited to this, and can be manufactured in various ways, such as being manufactured separately from each other.

[0067] According to another embodiment of the present invention, when forming cup portions in a pouch film laminate, two symmetrical cup portions 222, 232 can be formed in a single pouch film laminate so that they are adjacent to each other. In this case, cup portions 222, 232 can be formed in the first case 220 and the second case 230, respectively, as shown in Figure 2. After housing the electrode assembly 260 in the housing portion 224 provided in the cup portion 222 of the first case 220, the bridge portion 240 formed between the two cup portions 222, 232 can be folded so that the two cup portions 222, 232 face each other. In this case, the cup portion 232 of the second case 230 can accommodate the electrode assembly 260 from above. Therefore, since the two cup portions 222, 232 accommodate one electrode assembly 260, an electrode assembly 260 that is even thicker can be accommodated than when there is only one cup portion 222. Furthermore, when the pouch-type battery case 210 is folded, one edge of the secondary battery 200 is formed, and the number of edges to be sealed during subsequent sealing processes can be reduced. This improves the process speed of the pouch-type secondary battery 200 and reduces the number of sealing steps.

[0068] The pouch-type battery case 210 can be sealed with the electrode assembly 260 housed inside such that a portion of the electrode lead 280, i.e., the terminal portion, is exposed. Specifically, when the electrode lead 280 is connected to the electrode tab 270 of the electrode assembly 260, and an insulating portion 290 is formed on a portion of the electrode lead 280, the electrode assembly 260 is 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, the electrolyte is injected into the housing portion 224, and the sealing portions 250 formed on the periphery of the first case 220 and the second case 230 can be sealed.

[0069] The sealing portion 250 can serve to seal the housing portion 224. Specifically, the sealing portion 250 can seal the housing portion 224 while being formed along the periphery of the housing portion 224. The sealing temperature of the sealing portion 250 can be 180°C to 250°C, specifically 200°C to 250°C, and more specifically 210°C to 240°C. When the sealing temperature meets the above numerical range, the pouch-type battery case 210 can ensure sufficient sealing strength through heat bonding.

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

[0071] The electrode assembly 260 can be formed by stacking a positive electrode, a separator, and a negative electrode in that order. 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.

[0072] The positive and negative electrodes can each be constructed by coating an active material slurry onto electrode current collectors in the form of metal foil or metal mesh containing aluminum and copper, respectively. The slurry can typically be formed by stirring granular active material, auxiliary conductors, binders, and conductive materials with a solvent. The solvent can be removed in a subsequent step.

[0073] A slurry of electrode active material and binder and / or conductive material is applied to a positive electrode current collector and a negative electrode current collector to manufacture the positive and negative electrodes, and these are then stacked on both sides of a separator to manufacture an electrode assembly 260 in a predetermined shape. Possible and not limited to the types of electrode assemblies 260 include stack type, jelly roll type, and stack-and-fold type.

[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 outward from the electrode assembly 260, becoming pathways through which electrons can move between the inside and outside of the electrode assembly 260. The electrode current collector included in the electrode assembly 260 can consist of a portion coated with electrode active material and an end portion not coated with electrode active material, i.e., a plain portion. The electrode tabs 270 can be formed by cutting the plain portion or by connecting another conductive member to the plain portion by ultrasonic welding or the like. As illustrated in Figure 2, the electrode tabs 270 may protrude in different directions from the electrode assembly 260, but are not limited to this, and can be formed to protrude in various directions, such as protruding parallel to the same direction from one side.

[0076] (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.

[0077] The electrode lead 280 is connected to the electrode assembly 260 and can protrude outside the pouch-type battery case 210 via the seal portion 250. Specifically, one end of the electrode lead 280 is connected to the electrode assembly 260, in particular to the electrode tab 270, and the other end of the electrode lead 280 can protrude outside the pouch-type battery case 210.

[0078] The electrode leads 280 may include a positive electrode lead 282, one end of which is connected to the positive electrode tab 272 and extends in the direction in which the positive electrode tab 272 protrudes, and a negative electrode lead 284, one end of which is connected to the negative electrode tab 274 and extends in the direction in which the negative electrode tab 274 protrudes. Both the positive electrode lead 282 and the negative electrode lead 284 can have their other ends protruding outside the battery case 210. Therefore, electricity generated inside the electrode assembly 260 can be supplied to the outside. Also, since the positive electrode tab 272 and the negative electrode tab 274 are formed to protrude in various directions, the positive electrode lead 282 and the negative electrode lead 284 can also extend in various directions. The positive electrode lead 282 and the negative electrode lead 284 may be made of different materials. In other words, the positive electrode lead 282 can be made of the same aluminum (Al) material as the positive electrode current collector, and the negative electrode lead 284 can be made of the same copper (Cu) material as the negative electrode current collector, or copper material coated with nickel (Ni). A portion of the electrode lead 280 that protrudes outside the battery case 210 becomes a terminal and can be electrically connected to an external terminal.

[0079] (4) Insulation The insulating portion 290 prevents electricity generated from the electrode assembly 260 from flowing through the electrode leads 280 to the battery case 210, thereby maintaining the seal of the battery case 210. For this purpose, the insulating portion 290 can be formed from an insulator that has non-conductive properties that make it difficult for electricity to pass through. Generally, insulating tape or film that adheres easily to the electrode leads 280 and is relatively thin is often used as the insulating portion 290, but it is not limited to this, and any material that can insulate the electrode leads 280 can be used.

[0080] The insulating portion 290 can be positioned to enclose the outer circumferential surface of the electrode lead 280. Specifically, at least a portion of the electrode lead 280 can be surrounded by the insulating portion 290. In this case, the insulating portion 290 can be positioned between the electrode lead 280 and the pouch-type battery case 210. The insulating portion 290 can be positioned exclusively within the sealing portion 250 where the first case 220 and the second case 230 of the pouch-type battery case 210 are heat-fused together, thereby allowing the electrode lead 280 to be bonded 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) that is injected into the inside of the pouch-type battery case 210. The electrolyte is for moving lithium ions generated by the electrochemical reaction of electrodes during charging / discharging of the secondary battery 200, and may include a non-aqueous organic electrolyte which is a mixture of lithium salts and organic solvents, 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 by external forces.

[0082] The present invention will be described more specifically below with reference to concrete examples. However, the following examples are illustrative to aid in understanding the present invention and do not limit its scope. It will be obvious to those skilled in the art that various changes and modifications are possible within the scope of the described concept and art, and it goes without saying that such variations and modifications fall within the scope of the appended claims.

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

[0084] Here, the polypropylene film is the sealant layer, the aluminum alloy thin film is the gas barrier layer, and the first adhesive film, nylon film, second adhesive film, and polyethylene terephthalate film are the substrate 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 amount of moisture in the air inside the chamber.

[0086] Example 2: Manufacturing of a pouch film laminate A pouch film laminate was manufactured using the same method 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 inside the chamber where the pouch film laminate was stored.

[0088] Example 3: Manufacturing of a pouch film laminate A pouch film laminate was manufactured using the same method 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 inside the chamber where the pouch film laminate was stored.

[0090] Example 4: Manufacturing of a pouch film laminate A pouch film laminate was manufactured 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 inside the chamber where the pouch film laminate was stored.

[0092] Example 5: Manufacturing of a pouch film laminate A pouch film laminate was manufactured 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 inside the chamber where the pouch film laminate was stored.

[0094] Comparative Example 1: Manufacturing of a pouch film laminate A pouch film laminate was manufactured using the same method 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 inside the chamber where the pouch film laminate was stored.

[0096] Comparative Example 2: Manufacturing of a Pouch Film Laminate A pouch film laminate was manufactured using the same method 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 inside the chamber where the pouch film laminate was stored.

[0098] Comparative Example 3: Manufacturing of a pouch film laminate A pouch film laminate was manufactured using the same method 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 inside the chamber where the pouch film laminate was stored.

[0100] Comparative Example 4: Manufacturing of a pouch film laminate A pouch film laminate was manufactured 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 inside the chamber where the pouch film laminate was stored.

[0102] Comparative Example 5: Manufacturing of a pouch film laminate A pouch film laminate was manufactured 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 inside the chamber where the pouch film laminate was stored.

[0104] Comparative Example 6: Manufacturing of a pouch film laminate A pouch film laminate was manufactured 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 inside the chamber where the pouch film laminate was stored.

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

[0107] Furthermore, the moisture content index of the second base material layer was calculated using the following formula 1 from the moisture content per unit weight of the pouch film laminate and the density of the pouch film laminate, 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 / cm³) 3 ) × Thickness of the pouch film laminate (μm) / Thickness of the second substrate layer (μm)

[0109] [Table 1]

[0110] Experimental Example 2: Evaluation of whether or not deformation occurs in the seal area Three pouch film laminates were prepared for each of the examples 1-5 and comparative examples 1-6. Then, each pouch film laminate was cut to 266 mm wide and 200 mm long, folded in half to a size of 133 mm wide x 200 mm long so that the sealant layer was in contact with the laminate, and the long edge (200 mm) was sealed under the following three conditions to produce pouch-type battery cases.

[0111] - Seal bar area 200mm x 8mm, sealed for 1.8 seconds under conditions of 210°C and surface pressure of 1.2MPa. - Seal bar area 200mm x 8mm, sealed for 1.8 seconds under conditions of 220°C and surface pressure of 1.0 MPa. - Seal bar area 200mm x 8mm, sealed for 1.8 seconds under conditions of 230°C and surface pressure of 0.9MPa.

[0112] Next, for each pouch-type battery case sealed at different temperatures, we visually inspected whether the seal area had deformed, based on the occurrence of air bubbles in the second substrate layer located at the seal. The results are shown in Table 2 below.

[0113] ○: The seal area deforms due to the formation of air bubbles. ×: No air bubbles were generated, and the seal remained undeformed.

[0114] [Table 2]

[0115] According to Tables 1 and 2, the moisture content index of the second substrate layer is 17,000 ppm·g / cm³. 3 In Examples 1 to 5, unlike Comparative Examples 1 to 6, it can be confirmed that no air bubbles are generated in the second substrate layer and the sealed portion of the pouch-type battery case does not deform even when sealed at a temperature of 220°C.

[0116] Furthermore, the moisture content index of the second substrate layer was 16,000 ppm·g / cm³. 3 In Examples 1, 2, and 4 described below, it can be confirmed that even when sealed at a temperature of 230°C, no air bubbles are generated in the second substrate layer and the sealed portion of the pouch-type battery case does 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 rechargeable batteries 210 pouch-type cases 220 Case 1 222 Cup section 224 Storage Unit 230 Case 2 232 Cup section 240 Bridge section 250 seal section 260 Electrode assembly 270 electrode tabs 272 Positive Tab 274 Negative Electrode Tab 280 electrode leads 282 Positive lead 284 Negative lead 290 Insulation part

Claims

1. It includes a first substrate layer, a second substrate layer, a gas barrier layer, and a sealant layer, which are stacked in order. The moisture content index of the second substrate layer, represented by the following formula 1, is 17,000 ppm·g / cm³. ３ The following is a laminated pouch film. [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 / cm³) ３ ) × Thickness of the pouch film laminate (μm) / Thickness of the second substrate 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 substrate layer is 10 μm to 50 μm.

4. The pouch film laminate according to claim 1, wherein the first substrate layer includes a polyester film.

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

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

8. 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 substrate layer is 220°C or higher.

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

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

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

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

14. A pouch-type battery case manufactured by molding a pouch film laminate according to any one of claims 1 to 12, A pouch-type secondary battery, comprising an electrode assembly housed in the aforementioned pouch-type battery case.

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