Bag film laminate, bag-shaped battery case, and bag-shaped secondary battery

Abstract

The present invention relates to a bag film laminate comprising a substrate layer, a barrier layer and a sealant layer laminated sequentially, wherein the bag film laminate comprises a silicone-based release coating coated on the sealant layer, the thickness of the silicone-based release coating is 1 μm or less, and the silicone-based release coating comprises a silicone-based release agent, wherein the silicone-based release agent is a crosslinked silicone-based polymer having a weight average molecular weight of less than 1,000,000 g / mol.

Description

Technical Field

[0001] Cross Reference to Related Applications

[0002] This application claims priority to Korean Patent Application No. 10-2024-0052218, filed on April 18, 2024, the disclosure of which is incorporated herein by reference. Technical Field

[0004] This invention relates to pouch-film laminates, pouch-type battery boxes, and pouch-type secondary batteries. Background Technology

[0005] Secondary batteries are used not only in small products such as digital cameras, P-DVDs, MP3 players, mobile phones, PDAs, portable gaming devices, power tools, and electric bicycles, but also in large products that require high output, such as electric vehicles and hybrid vehicles, as well as energy storage devices and backup energy storage devices that store surplus generated electricity or renewable energy.

[0006] Typically, secondary batteries are prepared by the following method: electrode active material slurry is applied to positive electrode current collector and negative electrode current collector respectively to prepare positive electrode and negative electrode, positive electrode and negative electrode are stacked on both sides of separator to form electrode assembly with predetermined shape, electrode assembly is then housed in battery case, and battery case is sealed after electrolyte is injected.

[0007] Secondary batteries are classified into pouch-type, can-type, etc., depending on the material used to house the electrode assembly. Pouch-type batteries house the electrode assembly in a pouch made of a flexible polymer material. Can-type batteries house the electrode assembly in a box made of a material such as metal or plastic.

[0008] The pouch-type battery case is fabricated by pressing a flexible pouch film laminate to form a cup-shaped portion. Then, once the cup-shaped portion is formed, the secondary battery is fabricated by housing the electrode assembly within the cup-shaped portion and sealing it with a seal.

[0009] In the pressing process, stretching is performed by inserting the bag film into a pressing device and applying pressure to the bag film laminate using a punch to stretch the bag film laminate. The bag film laminate typically consists of multiple layers in which a polymer film (e.g., polyethylene terephthalate) is laminated on one surface of a gas barrier layer formed of metal and a sealing layer is laminated on the other surface.

[0010] Recently, with the increasing demand for high-capacity batteries (such as batteries for electric vehicles and energy storage systems (ESS) batteries), the demand for battery boxes that can accommodate more electrode components is also increasing. Therefore, efforts are being made to increase the forming depth of the cup-shaped portion of pouch-type battery boxes, or to explore a double-cup forming method, in which a cup-shaped portion is formed in each of the upper and lower boxes to increase the volume of the cup-shaped portion.

[0011] In the preparation of conventional bag-film composites, a lubricant is included in the innermost sealing layer of the bag film or applied to the surface of the sealing layer to prevent adhesion between the bag films and to facilitate post-processing. However, this method has the problem that during bag molding in the secondary battery manufacturing process, the lubricant contaminates the molding die due to the presence of lubricant components on the surface of the sealing layer.

[0012] Therefore, there is a need to develop bag-film laminates to improve processability by preventing contamination of molding dies and to improve the productivity of secondary batteries by reducing cleaning frequency. Summary of the Invention

[0013] Technical issues

[0014] One aspect of the present invention provides a pouch-film laminate, a pouch-type battery box, and a pouch-type secondary battery that improves processability by preventing contamination of the molding die, while reducing the coefficient of friction and improving wrinkles and formability degradation that occur during cup-shaped part molding.

[0015] Technical solution

[0016] [1] The present invention provides a bag-film laminate comprising a substrate layer, a gas barrier layer and a sealing layer sequentially laminated, wherein the bag-film laminate includes a silicone-based release coating applied to the sealing layer, the silicone-based release coating having a thickness of 1 μm or less, and the silicone-based release coating comprising a silicone-based release agent, wherein the silicone-based release agent is a crosslinked silicone-based polymer with a weight average molecular weight of less than 1,000,000 g / mol.

[0017] [2] In the bag film laminate of [1] above, the organosilicon-based polymer may be selected from at least one of polydimethylsiloxane (PDMS), polysilane, polycarbosilane and polysilazane.

[0018] [3] In the bag film composite of [1] or [2] above, the silicone-based release coating contains a polyolefin-based resin, and the silicone-based release coating may contain a silicone-based release agent in an amount of 80% by weight or more based on the total weight of the silicone-based release coating.

[0019] [4] In at least one of the bag film composites described in [1] to [3] above, the amount of lubricant present on the surface of the sealing layer may be less than 1 mg / m 2 .

[0020] [5] In at least one of the bag film composites above [1] to [4], the sealing layer may have a coefficient of friction of 0.05 to 0.30.

[0021] [6] In at least one of the bag film composites [1] to [5] above, the substrate layer may comprise at least one of polyethylene terephthalate (PET) and nylon.

[0022] [7] In at least one of the bag film composites above [1] to [6], the thickness of the substrate layer may be from 5 μm to 70 μm.

[0023] [8] In at least one of the bag membrane composites above [1] to [7], the gas barrier layer may contain at least one metal selected from aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti) and Invar.

[0024] [9] In at least one of the bag membrane composites [1] to [8] above, the thickness of the gas barrier layer can be from 20 μm to 100 μm.

[0025]

[10] In at least one of the bag film composites [1] to [9] above, the sealing layer may comprise at least one selected from polypropylene (PP), acid-modified polypropylene (PPa), and cast polypropylene (CPP).

[0026]

[11] In at least one of the bag film composites above [1] to

[10] , the sealing layer may have a thickness of 30 μm to 130 μm.

[0027]

[12] In at least one of the bag film laminates above [1] to

[11] , the bag film laminate may have a thickness of 120 μm to 300 μm.

[0028]

[13] The present invention provides a pouch-type battery box, which is prepared by stretching at least one of the pouch film layers of [1] to

[12] above.

[0029]

[14] The present invention provides a pouch-type secondary battery, which includes the pouch-type battery box described above

[13] .

[0030] Beneficial effects

[0031] Since the bag-film laminate according to the invention reduces the coefficient of friction by forming a silicone-based release coating on the sealing layer and does not contain lubricant, it improves processability by reducing the lubricant cleaning cycle of the molding die and improves the formability of the bag-film laminate by preventing wrinkles that occur during cup forming. Attached Figure Description

[0032] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the detailed description, serve to provide an explanation of the principles of the disclosure, but are not intended to limit the scope of the disclosure thereto. On the other hand, for clarity, the shape, size, scale, or proportion of elements in the drawings shown herein may be enlarged.

[0033] Figure 1 This is a cross-sectional view of the bag-film laminate according to the present invention.

[0034] Figure 2 This is an exploded assembly diagram of the secondary battery according to the present invention. Detailed Implementation

[0035] The invention will be described in more detail below.

[0036] It should be understood that the words or terms used in the specification and claims should not be interpreted as having the meaning defined in a common dictionary, and it should be further understood that the words or terms should be interpreted as having a meaning consistent with their meaning in the context of the relevant field and technical concept of the invention, based on the inventor's ability to appropriately define the meaning of the words or terms to best illustrate the principles of the invention.

[0037] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to limit the invention. In this specification, singular terms may include plural forms unless otherwise stated. It should be further understood that, when used in this specification, the terms “comprising” and / or “including” expressly specify the presence of the said component, but do not exclude the presence or addition of one or more other components.

[0038] <Bag-film laminate>

[0039] First, the bag film laminate 1 according to the present invention will be described. Figure 1 The image shows a bag film laminate 1 according to the present invention.

[0040] Reference Figure 1 The bag film laminate 1 according to the present invention includes a substrate layer 10, a gas barrier layer 20 and a sealing layer 30 sequentially laminated, and includes a silicone-based release coating 40 on the sealing layer 30.

[0041] In the preparation of conventional bag film laminates, to prevent adhesion between the laminates and facilitate post-processing, lubricant is often included in the innermost sealing layer of the bag film or applied to the surface of the sealing layer to ensure its presence. However, this results in reduced processability because the molding die becomes contaminated with lubricant on the sealing layer surface, requiring frequent cleaning.

[0042] Therefore, when the surface of the sealing layer is coated with a separate silicone-based release coating, a bag-film composite with better processability and formability than when a lubricant is included or applied can be prepared.

[0043] In the following text, reference will be made to Figure 1 The various configurations of the bag-film laminate according to the present invention will be described in more detail.

[0044] (1) Substrate layer

[0045] The substrate layer 10 is configured as the outermost layer of the battery box to protect the electrode assembly from external impacts and to electrically insulate it, wherein the substrate layer 10 may contain at least one of polyethylene terephthalate (PET) and nylon.

[0046] According to one embodiment, the substrate layer 10 may have a laminated structure of a polyethylene terephthalate (PET) film 12 and a nylon film 14. In this case, it is preferable that the nylon film 14 is disposed toward (i.e., on the inside) the gas barrier layer 20, and the polyethylene terephthalate film 12 is disposed toward the surface of the battery compartment.

[0047] Because polyethylene terephthalate (PET) possesses excellent durability and electrical insulation properties, its durability and insulation properties are excellent when the PET film is positioned facing the surface. However, due to the weak adhesion of the PET film to the aluminum alloy film constituting the gas barrier layer 20 and its different stretching behavior, delamination between the substrate layer and the gas barrier layer may occur during the molding process when the PET film is positioned facing the gas barrier layer. Furthermore, the formability may be reduced due to uneven stretching of the gas barrier layer. In contrast, since nylon film has similar stretching behavior to the aluminum alloy film constituting the gas barrier layer 20, improving formability can be achieved when the nylon film is positioned between the polyethylene terephthalate and the gas barrier layer.

[0048] The thickness of the substrate layer 10 can be from 5 μm to 70 μm, particularly from 7 μm to 65 μm, and even more particularly from 10 μm to 60 μm. When these ranges are met, the formability and post-molding rigidity can be excellent.

[0049] Furthermore, when the substrate layer 10 has a laminated structure of polyethylene terephthalate (PET) film 12 and nylon film 14, the thickness of the PET film can be from 5 μm to 30 μm, particularly from 7 μm to 30 μm, and more particularly from 10 μm to 27 μm, and the thickness of the nylon film can be from 10 μm to 60 μm, particularly from 10 μm to 55 μm, and more particularly from 15 μm to 50 μm. When the thicknesses of the PET film and the nylon film meet the above ranges, the formability and rigidity after molding can be excellent.

[0050] (2) Gas barrier layer

[0051] The gas barrier layer 20 is laminated between the substrate layer 10 and the sealing layer 30 to ensure the mechanical strength of the bag, prevent gas or moisture from the outside of the secondary battery from flowing in and out, and prevent electrolyte from leaking from the inside of the bag-type battery box.

[0052] The gas barrier layer 20 can be formed of metal. For example, the gas barrier layer can be a metal film containing at least one metal selected from aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti), and Invar, but is not limited thereto.

[0053] According to one embodiment of the present invention, the gas barrier layer 20 can be formed of an aluminum alloy thin film. When the gas barrier layer 20 is formed using an aluminum alloy thin film, the gas barrier layer 20 is lightweight while ensuring mechanical strength above a predetermined level, compensating for the electrochemical characteristics of the electrode assembly and the electrolyte, and ensuring heat dissipation characteristics. The aluminum alloy thin film may contain elements other than aluminum (Al). For example, the aluminum alloy thin film may contain at least one selected from iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0054] In another example, the gas barrier layer 20 can be formed of a stainless steel film. Specifically, the gas barrier layer 20 can be prepared by forming and / or processing a stainless steel film. Because the gas barrier layer 20 formed of stainless steel has relatively low thermal conductivity, it is effective in preventing or delaying heat diffusion to other battery cells during thermal runaway, and because of its relatively high toughness, it can suppress the formation of cracks in the pouch during use of the pouch battery. The stainless steel may contain elements other than iron (Fe), for example, at least one selected from copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0055] The thickness of the gas barrier layer 20 can be from 20 μm to 100 μm, preferably from 30 μm to 90 μm, and more preferably from 40 μm to 85 μm. When the thickness meets these ranges, it is desirable that the layer can adequately prevent the inflow and outflow of gases or moisture from the outside of the secondary battery, and can adequately prevent electrolyte leakage from the inside of the pouch-type battery case. Furthermore, it can improve the formability and gas barrier performance during the molding of the cup-shaped portion.

[0056] (3) Sealing layer

[0057] The sealing layer 30 is used to completely seal the interior of a pouch battery case, in which electrode assemblies are housed, by thermally bonding them together at the sealing portion. For this purpose, the sealing layer 30 can be formed of a material with excellent thermal bonding strength.

[0058] The sealing layer 30 can be formed of a material with insulating, corrosion-resistant, and sealing properties. Specifically, since the sealing layer 30 is in direct contact with the electrode components and / or electrolyte inside the pouch battery case, it can be formed of a material with insulating and corrosion-resistant properties. Furthermore, since the sealing layer 30 completely seals the interior of the pouch battery case to prevent material movement between the interior and exterior, it can be formed of a material with high sealing properties (e.g., excellent thermal bonding strength). To ensure such insulating, corrosion-resistant, and sealing properties, the sealing layer 30 can be formed of a polymer material.

[0059] The sealing layer 30 may comprise at least one material selected from polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, nylon, polyester, poly(p-phenylenebenzobis(II)), polyarylate, and Teflon, and may specifically comprise a polyolefin-based resin, such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may be composed of cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butene-ethylene terpolymer. More specifically, the sealing layer 30 may comprise at least one selected from polypropylene (PP), acid-modified polypropylene (PPa), and cast polypropylene (CPP), and even more specifically, from the gas barrier side, the sealing layer 30 may be formed of any of the following: a laminate of acid-modified polypropylene and polypropylene, a laminate of acid-modified polypropylene and cast polypropylene, or a single layer of cast polypropylene.

[0060] The amount of lubricant present on the surface of the sealing layer 30 can be less than 1 mg / m 2 Especially less than 0.8 mg / m 2 And more specifically less than 0.5 mg / m 2Even with lubricants encompassing the above range, the present invention maintains appropriate friction due to the presence of a separate silicone release coating, and improves processability by extending the lubricant cleaning cycle due to reduced mold contamination caused by the small amount of lubricant.

[0061] The coefficient of friction of the sealing layer 30 can be from 0.05 to 0.30, particularly from 0.1 to 0.2, and even more particularly from 0.12 to 0.18. When the above ranges are met, the sliding characteristics of the sealing layer are appropriately improved, so even if physical deformation occurs in the sealing layer during molding, the occurrence of defects such as cracks is reduced, and whitening can be reduced.

[0062] The thickness of the sealing layer 30 can be from 30 μm to 130 μm, particularly from 40 μm to 120 μm, and even more particularly from 60 μm to 100 μm. When the thickness of the sealing layer meets the above ranges, it has the effect of ensuring the sealing strength of the sealing part while ensuring the formability of the bag film layer assembly.

[0063] The sealing layer 30 according to the invention can have a composite layer structure formed by laminating two or more materials respectively. For example, the sealing layer 30 can have a multilayer structure. An adhesive layer and / or a surface layer can be provided between the individual layers of the sealing layer 30 having a composite layer structure. Since the adhesive layer and / or the surface layer have thermal adhesive properties, they can serve to facilitate adhesion between the individual layers of the sealing layer 30. For example, the adhesive layer and / or the surface layer can contain a polypropylene-based resin, but is not limited thereto. Furthermore, an adhesive layer and / or a surface layer can be provided between the sealing layer 30 and the gas barrier layer 20.

[0064] (4) Silicone-based release coating

[0065] According to one embodiment of the invention, a silicone-based release coating 40 is applied to the sealing layer 30, wherein the thickness of the silicone-based release coating 40 is characterized as 1 μm or less, and may specifically be 0.5 μm or less, more specifically 0.1 μm or less.

[0066] When the thickness of the silicone-based release coating meets the above range, the sealing strength can be ensured due to the small thickness. However, when the thickness of the silicone-based release coating is greater than 1 μm, the sealing strength is reduced because the silicone-based polymer and polypropylene cannot mix well at the interface during bag sealing.

[0067] The silicone-based release coating 40 comprises a silicone-based release agent, and the silicone-based release agent is characterized as a crosslinked silicone-based polymer with a weight-average molecular weight of less than 1,000,000 g / mol.

[0068] There are no particular limitations on the silicone-based polymer, as long as it provides sliding properties, but it can specifically be selected from at least one of polydimethylsiloxane (PDMS), polysilane, polycarbosilane, and polysilazane, and more specifically polydimethylsiloxane (PDMS). When the silicone-based release coating contains a silicone-based polymer, unlike when using a lubricant, the processability can be excellent because the cleaning cycle is extended due to reduced contamination of the molding die; the processability can also be improved because the failure rate due to contamination is reduced; wrinkles do not occur during cup-shaped part molding; and the maximum molding depth can be excellent.

[0069] Silicon-based polymers are characterized by a weight-average molecular weight of less than 1,000,000 g / mol, and more specifically, less than 900,000 g / mol, and more specifically, less than 600,000 g / mol. When the weight-average molecular weight of the silicone-based polymer is 1,000,000 g / mol or greater, there is a problem of reduced coatability due to the high viscosity.

[0070] Weight-average molecular weight can be expressed as the equivalent value of standard polystyrene measured by gel permeation chromatography (GPC), and unless otherwise stated, molecular weight can be expressed as weight-average molecular weight. For example, the weight-average molecular weight in this invention is measured using the Agilent Technologies 1200 series, in which case an Agilent Technologies PL mixed B column can be used, and tetrahydrofuran (THF) can be used as the solvent.

[0071] Silicone-based mold release agents are characterized by being cross-linked silicone-based polymers. In the absence of cross-linking of the silicone-based polymer, the silicone may migrate to the molding die due to potentially weakened physical properties, thereby contaminating the molding die.

[0072] In addition to silicone-based polymers, silicone-based release coatings can also contain polyolefin-based resins, such as polyethylene (PE) and polypropylene (PP). The inclusion of polyolefin-based resins can advantageously maintain the adhesion between the silicone-based release coating and the sealing layer of the bag film assembly, and can ensure heat resistance because its melting point is higher than that of the silicone-based polymers.

[0073] Based on the total weight of the silicone-based release coating, the silicone-based release coating 40 may contain polydimethylsiloxane (PDMS) in an amount of 80% by weight or more, particularly 85% by weight or more, and more particularly 90% by weight or more. When the weight ratio of polydimethylsiloxane (PDMS) satisfies the above ranges, appropriate friction is generated due to the sliding properties of PDMS when mixed with the crosslinking agent, thus preventing the layer-to-layer adhesion during the preparation of the bag film composite.

[0074] The silicone-based release coating 40 can be formed by coating the sealing layer 30. There are no particular limitations on the coating method, and known coating methods can be used, such as slot die coating, gravure coating, spin coating, spray coating, roll coating, curtain coating, extrusion, casting, screen printing, inkjet printing, chemical vapor deposition (CVD), or physical vapor deposition (PVD).

[0075] The bag-film laminate according to the invention described above can be prepared by methods known in the art for preparing bag-film laminates. For example, the bag-film laminate according to the invention can be prepared by attaching the substrate layer 10 to the upper surface of the gas barrier layer 20 using an adhesive, forming a sealing layer 30 on the lower surface of the gas barrier layer 20 by co-extrusion or an adhesive layer, and coating the lower surface of the sealing layer 30 with a silicone-based release coating 40 by heat treatment. It can also be prepared by methods such as dry lamination and sandwich lamination. However, the methods for preparing the bag-film laminate are not limited to these.

[0076] The thickness of the bag-film laminate according to the invention can be from 120 µm to 300 µm, particularly from 130 µm to 280 µm, and more particularly from 140 µm to 250 µm. When the thickness of the bag-film laminate meets the above range, the molding depth can be increased while minimizing the reduction in sealing durability or the reduction in battery housing space caused by the increase in the thickness of the bag-film laminate.

[0077] <Pouch-type secondary batteries>

[0078] Next, the pouch-type secondary battery 200 according to the present invention will be described. Figure 2 An exploded assembly diagram of the pouch-type secondary battery 200 according to the present invention is shown.

[0079] like Figure 2As shown, the pouch-type secondary battery 200 according to the present invention may include a pouch-type battery case 210 prepared by molding the aforementioned pouch film layers together, and an electrode assembly 260 housed in the pouch-type battery case 210. Specifically, the pouch-type secondary battery 200 according to the present invention may include a pouch-type battery case 210, an electrode assembly 260, electrode leads 280, an insulating portion 290, and an electrolyte (not shown).

[0080] In the following text, reference will be made to Figure 2 The various configurations of the pouch-type secondary battery according to the present invention will be described in more detail.

[0081] (1) Pouch-type battery box

[0082] The pouch-type battery case 210 can be manufactured by molding the pouch-film laminate according to the present invention. The pouch-type battery case 210 can internally house the electrode assembly 260. Since the detailed configuration and physical properties of the pouch-film laminate are the same as described above, a detailed description is omitted.

[0083] The pouch-type battery box 210 can be prepared by drawing and stretching the pouch film composite using a stamping machine or the like. Therefore, the pouch-type battery box 210 may include a cup-shaped portion 222 and a receiving portion 224. The receiving portion 224 is a place for accommodating electrode components, which may refer to a receiving space formed in a pocket shape inside the cup-shaped portion 222 when the cup-shaped portion 222 is formed.

[0084] 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 FIG3. The first case 220 includes a receiving portion 224 capable of accommodating an electrode assembly 260, and the second case 230 can cover the receiving portion 224 from the top so that the electrode assembly 260 does not detach from the outside of the battery case 210. As shown in FIG3, the first case 220 and the second case 230 can be prepared by connecting one side of them to each other, but the invention is not limited thereto, and the first case and the second case can be prepared in various ways, for example, the first case and the second case can be separated from each other and prepared separately.

[0085] According to another embodiment of the invention, where the cup-shaped portions are formed on the pouch film laminate, two symmetrical cup-shaped portions 222 and 232 can be drawn adjacent to each other on a pouch film laminate. In this case, as shown in FIG3, the cup-shaped portions 222 and 232 can be formed in the first box 220 and the second box 230, respectively. After the electrode assembly 260 is accommodated in the receiving portion 224 provided in the cup-shaped portion 222 of the first box 220, the bridging portion 240 formed between the two cup-shaped portions 222 and 232 can be folded so that the two cup-shaped portions 222 and 232 face each other. In this case, the cup-shaped portion 232 of the second box 230 can accommodate the electrode assembly 260 from above. Therefore, since the two cup-shaped portions 222 and 232 accommodate one electrode assembly 260, an electrode assembly 260 with a greater thickness than when there is only one cup-shaped portion 222 can be accommodated. Furthermore, since one edge of the secondary battery 200 is formed by folding the pouch-shaped battery case 210, the number of edges to be sealed during the subsequent sealing process can be reduced. Therefore, the processing speed of the pouch-shaped secondary battery 200 can be improved, and the number of sealing processes can be reduced.

[0086] The pouch-type battery case 210 can be sealed while housing the electrode assembly 260, exposing a portion of the electrode lead 280, i.e., the terminal portion, which will be described later. 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 in this portion of the electrode lead 280, the electrode assembly 260 is housed in a receiving portion 224 provided in the cup-shaped portion 222 of the first case 220, and the second case 230 can cover the receiving portion 224 from the top. Subsequently, electrolyte is injected into the receiving portion 224, and the sealing portions 250 formed on the edges of the first case 220 and the second case 230 can be sealed.

[0087] The sealing portion 250 can be used to seal the receiving portion 224. Specifically, the sealing portion 250 can seal the receiving portion 224 while being formed along its edge. The temperature at which the sealing portion 250 is sealed can be in the range of 180°C to 250°C, particularly 200°C to 250°C, and more particularly 210°C to 240°C. When the sealing temperature meets the above numerical range, the pouch-type battery box 210 can ensure sufficient sealing strength through thermal bonding.

[0088] (2) Electrode assembly

[0089] The electrode assembly 260 can be inserted into the pouch battery case 210 and can be sealed by the pouch battery case 210 after electrolyte is injected.

[0090] Electrode assembly 260 can be formed by sequentially stacking a positive electrode, a spacer, and a negative electrode. Specifically, electrode assembly 260 may include two types of electrodes (e.g., a positive electrode and a negative electrode) and spacers disposed between the electrodes to insulate them from each other.

[0091] The positive and negative electrodes can be structures in which an active material slurry is applied to an electrode current collector in the form of a metal foil or metal mesh containing aluminum and copper, respectively. The slurry is typically formed by stirring granular active material, auxiliary conductors, binders, and conductive agents in the presence of a solvent. The solvent can be removed in subsequent processes.

[0092] A slurry containing a mixture of electrode active materials, binders, and / or conductive agents is applied to a positive electrode current collector and a negative electrode current collector to prepare positive and negative electrodes. The electrode assembly 260 can be prepared in a predetermined shape by stacking the positive and negative electrodes on both sides of a separator. The type of electrode assembly 260 may include, but is not limited to, stacked, wound, and stacked-folded types.

[0093] The electrode assembly 260 may include electrode tabs 270.

[0094] Electrode tabs 270 are connected to each of the positive and negative electrodes of the electrode assembly 260 and protrude outward from the electrode assembly 260, such that electrode tabs 270 can serve as a path for electrons to move between the interior and exterior of the electrode assembly 260. The electrode current collector included in the electrode assembly 260 can be composed of a portion to which electrode active material is applied and an end to which no electrode active material is applied (i.e., an uncoated portion). Electrode tabs 270 can be formed by cutting the uncoated portion, or by connecting individual conductive members to the uncoated portion via ultrasonic welding or the like. Figure 2 As shown, the electrode tabs 270 may protrude in different directions of the electrode assembly 260, but are not limited thereto, and may be formed to protrude in various directions, for example, the electrode tabs may protrude side by side from one side of the electrode assembly in the same direction.

[0095] (3) Electrode leads

[0096] Electrode lead 280 can supply power to the external source of secondary battery 200. Electrode lead 280 can be connected to electrode tab 270 of electrode assembly 260 by spot welding or the like.

[0097] Electrode leads 280 are connected to electrode assemblies 260 and can protrude to the outside of the pouch-type battery case 210 via sealing portions 250. Specifically, one end of electrode leads 280 is connected to electrode assemblies 260, particularly electrode tabs 270, and the other end of electrode leads 280 can protrude to the outside of the pouch-type battery case 210.

[0098] Electrode leads 280 may include a positive lead 282 and a negative lead 284. The positive lead 282 has one end connected to a positive electrode tab 272 and extends in the protruding direction of the positive electrode tab 272. The negative lead 284 has one end connected to a negative electrode tab 274 and extends in the protruding direction of the negative electrode tab 274. The other ends of both the positive lead 282 and the negative lead 284 may protrude to the outside of the battery case 210. Therefore, electricity generated inside the electrode assembly 260 can be supplied to the outside. Furthermore, since the positive electrode tab 272 and the negative electrode tab 274 are formed to protrude in different directions, the positive lead 282 and the negative lead 284 may also extend in different directions. The materials of the positive lead 282 and the negative lead 284 may be different from each other. That is, the positive electrode lead 282 can be formed of the same aluminum (Al) material as the positive electrode current collector, and the negative electrode lead 284 can be formed of the same copper (Cu) material as the negative electrode current collector or a copper material coated with nickel (Ni). Since the portion of the electrode lead 280 that protrudes to the outside of the battery case 210 becomes a terminal portion, it can be electrically connected to an external terminal.

[0099] (4) Insulation part

[0100] The insulating portion 290 prevents electricity generated from the electrode assembly 260 from flowing through the electrode lead 280 to the battery case 210 and maintains the seal of the battery case 210. For this purpose, the insulating portion 290 can be formed of a non-conductive insulator that does not conduct electricity well. Typically, insulating tape or insulating film that is easy to attach to the electrode lead 280 and is relatively thin is widely used as the insulating portion 290, but the invention is not limited to this, and any component capable of insulating the electrode lead 280 can be used.

[0101] The insulating portion 290 can be configured to surround the outer peripheral 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 disposed between the electrode lead 280 and the pouch-type battery case 210. The insulating portion 290 can be positioned at the sealing portion 250 where the first case 220 and the second case 230 of the pouch-type battery case 210 are thermally fused, and can adhere the electrode lead 280 to the battery case 210.

[0102] (5) Electrolytes

[0103] The pouch-type secondary battery 200 according to the invention may further include an electrolyte (not shown) injected into the pouch-type battery case 210. The electrolyte is used to move lithium ions generated by the electrochemical reaction of the electrodes during charging / discharging of the secondary battery 200, wherein the electrolyte may include a non-aqueous organic electrolyte as a mixture of lithium salt and organic solvent, or a polymer electrolyte. Furthermore, the electrolyte may include a sulfide-based, oxide-based, or polymer-based solid electrolyte, and the solid electrolyte may have flexibility that is easily deformed by external force.

[0104] The present invention will be described in detail below with reference to specific embodiments. However, the following embodiments are presented merely as illustrations of the invention, and the scope of the invention is not limited thereto. It will be apparent to those skilled in the art that various modifications and changes can be made within the scope and spirit of the invention. Such modifications and changes fall within the scope of the claims included herein.

[0105] Examples and Comparative Examples

[0106] Example 1: Preparation of bag-film composite

[0107] A sealing layer comprising sequentially laminated acid-modified polypropylene (PPa) and polypropylene (PP) with a total thickness of 80 μm was prepared, and an organosilicon-based release coating of 0.1 μm was applied to the sealing layer, consisting only of cross-linked polydimethylsiloxane (PDMS) with a weight average molecular weight of 590,000 g / mol.

[0108] Subsequently, a second adhesive film, a 25 μm thick nylon film, a first adhesive film, and a 12 μm thick polyethylene terephthalate (PET) film are sequentially laminated on one surface of a 60 μm thick aluminum alloy film, and the sealing layer coated with a silicone-based release coating is sequentially laminated on the other surface of the aluminum alloy film.

[0109] As a result, a bag-film laminate with the following structure was prepared: wherein the above-prepared silicone-based release coating / sealing layer (polypropylene / acid-modified polypropylene) / aluminum alloy film / second adhesive film / nylon film / first adhesive film / polyethylene terephthalate film were sequentially laminated.

[0110] Example 2: Preparation of bag-film composite

[0111] The bag-film composite was prepared in the same manner as in Example 1, except that a silicone-based release coating was applied to a thickness of 0.5 μm.

[0112] Example 3: Preparation of bag-film composite

[0113] The bag-film composite was prepared in the same manner as in Example 1, except that a silicone-based release coating was applied to a thickness of 1.0 μm.

[0114] Example 4: Preparation of bag-film composite

[0115] The bag-film composite was prepared in the same manner as in Example 1, except that cross-linked polydimethylsiloxane (PDMS) with a weight-average molecular weight of 800,000 g / mol was used.

[0116] Example 5: Preparation of bag-film composite

[0117] The bag-film composite was prepared in the same manner as in Example 1, except that the silicone-based release coating was prepared by mixing 80% by weight of polydimethylsiloxane (PDMS) and 20% by weight of polypropylene (PP) based on the total weight of the silicone-based release coating.

[0118] Example 6: Preparation of bag-film composite

[0119] The bag-film composite was prepared in the same manner as in Example 1, except that the silicone-based release coating was prepared by mixing 70% by weight of polydimethylsiloxane (PDMS) and 30% by weight of polypropylene (PP) based on the total weight of the silicone-based release coating.

[0120] Comparative Example 1: Preparation of Bag-Film Composite

[0121] The bag-film composite was prepared in the same manner as in Example 1, except that a silicone-based release coating was applied to a thickness of 2.0 μm.

[0122] Comparative Example 2: Preparation of Bag-Film Composite

[0123] The bag-film composite was prepared in the same manner as in Example 1, except that a separate silicone-based release coating was not formed, and a lubricant (erucamide) was applied to the surface of the sealing layer at an amount of 4 mg / m². 2 .

[0124] Comparative Example 3: Preparation of Bag-Film Composite

[0125] The bag-film composite was prepared in the same manner as in Example 1, except that a separate silicone-based release coating was not formed, and a lubricant (erucamide) was applied to the surface of the sealing layer at an amount of 26 mg / m². 2 .

[0126] Comparative Example 4: Preparation of Bag-Film Composite

[0127] The bag-film composite was prepared in the same manner as in Example 1, except that cross-linked polydimethylsiloxane (PDMS) with a weight-average molecular weight of 1,100,000 g / mol was used.

[0128] However, in this case, the viscosity of the silicone-based release agent increases excessively due to its high weight-average molecular weight, thus preventing the formation of a silicone-based release coating.

[0129] Experimental Example 1: Measurement of Friction Coefficient

[0130] The coefficient of friction of each bag film composite prepared according to Examples 1 to 6 and Comparative Examples 1 to 3 was measured.

[0131] As a method for measuring the coefficient of friction, the measurement is performed by bringing a slider metal with dimensions of 130 mm (machine direction (MD)) × 65 mm (transverse direction (TD)) and a weight of 200 g into contact with a silicone-based release coating of a bag film composite with dimensions of 300 mm (MD) × 200 mm (TD).

[0132] Specifically, the slider metal is moved 100 mm on the sealing layer at a speed of 100 mm / min, and the coefficient of friction is measured by taking the average of the kinetic friction coefficients from 5 measurements within the range of 20 mm to 80 mm.

[0133] The measurement results are presented in Table 1 below.

[0134] Experimental Example 2: Evaluation of the formability of bag-film composites

[0135] (1) Evaluation of molding depth

[0136] The formability of each bag film composite prepared according to Examples 1 to 6 and Comparative Examples 1 to 3 was evaluated.

[0137] As a method for evaluating the formability of the bag film laminate, after cutting each bag film laminate into identical dimensions of 300 mm (MD) × 400 mm (TD), the maximum forming depth without cracking was recorded while varying the forming depth in a battery box forming apparatus having two forming sections of 61 mm (MD) × 159 mm (TD). In this paper, the corners and edges of the forming sections of the press and battery box forming apparatus were chamfered. The corners of the press had a curvature of 2 mm, and its edges had a curvature of 0.5 mm. The corners of the forming sections had a curvature of 2.5 mm, and its edges had a curvature of 1 mm. Furthermore, the gap between the press and the forming sections was 0.5 mm.

[0138] The measured forming depths are listed in Table 1 below.

[0139] (2) Assessment of the presence of wrinkles

[0140] When forming the bag film using an uncontaminated forming device during the forming depth assessment, if wrinkles appear in the cup-shaped portion of the bag film layer at the maximum forming depth, it is assessed as O; otherwise, it is assessed as X.

[0141] The presence of wrinkles is listed in Table 1 below.

[0142] Experimental Example 3: Measurement of Lubricant Cleaning Cycle During Bag-Film Layer Assembly Molding

[0143] The lubricant cleaning cycle was measured when each bag film layer prepared according to Examples 1 to 6 and Comparative Examples 1 to 3 was assembled.

[0144] Specifically, during continuous production of a bag-film composite in which a cup-shaped portion with maximum forming depth is formed, the lubricant cleaning cycle is measured based on the maximum number of strokes without wrinkles.

[0145] The measurement results are listed in Table 1 below.

[0146] Experiment Example 4: Measurement of Sealing Strength

[0147] The sealing strength of each bag film layer assembly prepared according to Examples 1 to 6 and Comparative Examples 1 to 3 was measured.

[0148] As a method for measuring the sealing strength of a bag-film laminate, a bag-shaped battery box with a sealing portion is prepared by cutting the bag-film laminate into a size of 266 mm wide and 200 mm long, then folding it into a size of 133 mm × 200 mm, so that the silicone-based release coatings come into contact with each other, and sealing the end of the long side (200 mm) for 1.6 seconds, 3 seconds or 5 seconds under the conditions of a sealing strip area of ​​200 mm × 8 mm, 200 °C and 0.1 MPa, respectively. The sealing strength of the bag-shaped battery box is measured according to each sealing time.

[0149] Specifically, the sealing strength is calculated by the maximum value of the tensile strength measured by cutting the seal formed in the pouch-type battery box at 15 mm intervals and pulling it at a speed of 5 mm / min in a 180° direction at room temperature using a universal testing machine (UTM).

[0150] Based on the calculated seal strength, cases where the measured seal strength is 10 kgf or greater are assessed as O, and cases where the measured seal strength is less than 10 kgf are assessed as X.

[0151] The evaluation results are listed in Table 1 below.

[0152] [Table 1]

[0153]

[0154] Referring to [Table 1], it can be determined that Examples 1 to 6 have a lower coefficient of friction or better formability than Comparative Examples 1 to 3.

[0155] Furthermore, regarding Examples 1 to 6, it can be determined that the lubricant cleaning cycle is longer than that of Comparative Examples 2 and 3, in which the lubricant is applied to the surface of the sealing layer, and no wrinkles occur during the assembly of the bag film layer.

[0156] [Explanation of reference numerals in the attached figures]

[0157] 1: Bag film layer combination

[0158] 10: Substrate layer

[0159] 12: Polyethylene terephthalate film

[0160] 14: Nylon membrane

[0161] 20: Gas barrier layer

[0162] 30: Sealing layer

[0163] 40: Silicone-based release coating

[0164] 200: Pouch-type secondary battery

[0165] 210: Bag-type box

[0166] 220: First box

[0167] 222: Cup-shaped part

[0168] 224: Reception Department

[0169] 230: Second box

[0170] 232: Cup-shaped part

[0171] 240: Bridging section

[0172] 250: Sealing part

[0173] 260: Electrode assembly

[0174] 270: Electrode tabs

[0175] 272: Positive electrode tab

[0176] 274: Negative electrode tab

[0177] 280: Electrode lead

[0178] 282: Positive lead

[0179] 284: Negative lead

[0180] 290: Insulation section

Claims

1. A bag-film laminate, comprising: The substrate layer, gas barrier layer, and sealing layer are sequentially laminated. The bag-film laminate includes a silicone-based release coating applied to the sealing layer. The thickness of the silicone-based release coating is 1 μm or less, and The silicone-based release coating contains a silicone-based release agent. The silicone-based release agent is a cross-linked silicone-based polymer with a weight-average molecular weight of less than 1,000,000 g / mol.

2. The bag-film laminate according to claim 1, wherein the organosilicon-based polymer is selected from at least one of polydimethylsiloxane (PDMS), polysilane, polycarbosilane, and polysilazane.

3. The bag-film laminate according to claim 1, wherein the silicone-based release coating comprises a polyolefin-based resin, and Based on the total weight of the silicone-based release coating, the silicone-based release coating contains the silicone-based release agent in an amount of 80% by weight or greater.

4. The bag-film laminate according to claim 1, wherein the amount of lubricant present on the surface of the sealing layer is less than 1 mg / m³. 2 .

5. The bag-film composite according to claim 1, wherein the coefficient of friction of the sealing layer is 0.05 to 0.

30.

6. The bag film composite of claim 1, wherein the substrate layer comprises at least one of polyethylene terephthalate (PET) and nylon.

7. The bag-film composite according to claim 1, wherein the thickness of the substrate layer is 5 μm to 70 μm.

8. The bag-film composite according to claim 1, wherein the gas barrier layer comprises at least one metal selected from aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti), and Invar.

9. The bag-film composite according to claim 1, wherein the thickness of the gas barrier layer is 20 μm to 100 μm.

10. The bag-film composite of claim 1, wherein the sealing layer comprises at least one selected from polypropylene (PP), acid-modified polypropylene (PPa), and cast polypropylene (CPP).

11. The bag-film composite according to claim 1, wherein the thickness of the sealing layer is 30 μm to 130 μm.

12. The bag-film laminate according to claim 1, wherein the thickness of the bag-film laminate is from 120 μm to 300 μm.

13. A pouch-shaped battery box prepared by stretching the pouch-film laminate according to claim 1.

14. A pouch-type secondary battery, comprising the battery case according to claim 13.

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