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

Abstract

The present invention relates to a pouch film laminate comprising a base layer, a gas barrier layer, and a sealant layer that are sequentially stacked, wherein the sealant layer comprises a first sealant layer disposed adjacent to the gas barrier layer and a second sealant layer stacked on the first sealant layer, the second sealant layer comprises polypropylene (PP) modified with siloxane, and the polypropylene (PP) modified with siloxane has a weight average molecular weight of 100,000-500,000.

Description

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

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0142705 dated October 18, 2024, the entire contents of which are incorporated herein.

[0003]

[0004] Technology field

[0005] The present invention relates to a pouch film laminate, a pouch-type battery case, and a pouch-type secondary battery.

[0006]

[0007] Secondary batteries are used not only in small products such as digital cameras, P-DVDs, MP3 players, mobile phones, PDAs, portable game devices, power tools, and E-bikes, but also in large products requiring high output such as electric vehicles and hybrid vehicles, as well as in power storage devices that store surplus power or new and renewable energy and backup power storage devices.

[0008] Typically, a secondary battery is manufactured by applying an electrode active material slurry to a positive electrode current collector and a negative electrode current collector to produce a positive electrode and a negative electrode, and then stacking them on both sides of a separator to form an electrode assembly of a predetermined shape, and then housing the electrode assembly in a battery case and sealing it after injecting an electrolyte.

[0009] Secondary batteries are classified into pouch type and can type depending on the material of the case housing the electrode assembly. The pouch type houses the electrode assembly in a pouch made of a flexible polymer material. The can type, on the other hand, houses the electrode assembly in a case made of materials such as metal or plastic.

[0010] A pouch-type battery case is manufactured by performing press processing on a flexible pouch film laminate to form a cup portion. Then, once the cup portion is formed, an electrode assembly is housed in the receiving space of the cup portion and a sealing portion is sealed to manufacture a secondary battery.

[0011] Among these press processes, drawing forming is performed by inserting a pouch film into a press machine and applying pressure to the pouch film laminate with a punch to stretch the pouch film laminate. The pouch film laminate is generally formed of multiple layers in which a polymer film, such as polyethylene terephthalate, is laminated on one side of a metal gas barrier layer, and a sealant layer is laminated on the other side.

[0012] Recently, as the demand for high-capacity batteries, such as those for electric vehicles or ESS batteries, has increased, there is a growing demand for battery cases capable of accommodating more electrode assemblies. Accordingly, a two-cup molding method is being attempted to increase the volume of the cup portion by increasing the molding depth of the cup portion of a pouch-type battery case or by molding the cup portion in the upper case and the lower case separately.

[0013] In the conventional manufacturing of pouch film laminates, a lubricant was included in the sealant layer of the innermost layer of the pouch film or a lubricant was applied to the surface of the sealant layer to prevent adhesion between pouch films and to facilitate subsequent processing. However, this method had a problem in which the lubricant contaminates the molding die during pouch molding in the secondary battery manufacturing process because the lubricant component is present on the surface of the sealant layer.

[0014] Therefore, there is a need to develop pouch film laminates to improve the productivity of secondary batteries by preventing contamination of molding dies, thereby increasing processability, and reducing the frequency of cleaning.

[0015]

[0016] The present invention aims to solve the above-mentioned problems by preventing contamination of the molding die to improve processability while lowering the coefficient of friction, and by providing a pouch film laminate, a pouch-type battery case, and a pouch-type secondary battery that improve wrinkles and reduced moldability occurring during cup molding.

[0017]

[0018] [1] The present invention provides a pouch film laminate comprising a sequentially laminated substrate layer, a gas barrier layer, and a sealant layer, wherein the sealant layer comprises a first sealant layer disposed adjacent to the gas barrier layer and a second sealant layer laminated on the first sealant layer, and the second sealant layer comprises polypropylene (PP) modified with siloxane, and the polypropylene (PP) modified with siloxane has a weight-average molecular weight of 100,000 to 500,000.

[0019] [2] The present invention provides a pouch film laminate according to [1], wherein the second sealant layer comprises 10% to 70% by weight of the siloxane-modified polypropylene (PP) with respect to the total weight of the second sealant layer.

[0020] [3] The present invention provides a pouch film laminate in which the thickness of the second sealant layer is 10 μm or more, in accordance with [1] or [2].

[0021] [4] The present invention, in at least one of [1] to [3], wherein the amount of lubricant present on the surface of the sealant layer is 1 mg / m² 2 Provides a pouch film laminate of less than

[0022] [5] The present invention provides a pouch film laminate in which, in at least one of [1] to [4], the coefficient of friction of the sealant layer is 0.05 to 0.30.

[0023] [6] The present invention provides a pouch film laminate in which, in at least one of [1] to [5], the substrate layer comprises one or more of polyethylene terephthalate (PET) and nylon.

[0024] [7] The present invention provides a pouch film laminate in which the thickness of the substrate layer is 5 μm to 70 μm, in at least one of [1] to [6].

[0025] [8] The present invention provides a pouch film laminate in which, in at least one of [1] to [7], the gas barrier layer comprises one or more metals selected from the group consisting of aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti) and Invar.

[0026] [9] The present invention provides a pouch film laminate in which the thickness of the gas barrier layer is 20 μm to 100 μm, in at least one of [1] to [8].

[0027]

[0010] The present invention provides a pouch film laminate comprising, in at least one of [1] to [9], a sealant layer selected from polypropylene (PP), acid-modified polypropylene (PPa), and unoriented polypropylene (CPP).

[0028]

[0011] The present invention provides a pouch film laminate in which, in at least one of [1] to

[0010] , the thickness of the sealant layer is 30 μm to 130 μm.

[0029]

[0012] The present invention provides a pouch film laminate in which the thickness of the pouch film laminate is 120 μm to 300 μm, in at least one of [1] to

[0011] .

[0030]

[0013] The present invention provides a pouch-type battery case manufactured by drawing molding a pouch film laminate according to at least one of [1] to

[0012] .

[0031]

[0014] The present invention provides a pouch-type secondary battery comprising the pouch-type battery case of

[0013] .

[0032]

[0033] The pouch film laminate according to the present invention includes polypropylene (PP) modified with siloxane having a weight-average molecular weight of 100,000 to 500,000 in the second sealant layer, thereby lowering the coefficient of friction, and does not include a separate lubricant, which lowers the lubricant cleaning cycle of the molding die, thereby improving processability, and prevents wrinkles that occur during cup molding, thereby improving the moldability of the pouch film laminate.

[0034]

[0035] The drawings attached to this specification illustrate preferred embodiments of the present invention and serve to help to better understand the technical concept of the present invention together with the description of the invention above; therefore, the present invention is not to be interpreted as being limited only to the matters described in such drawings. Meanwhile, the shape, size, scale, or ratio of elements in the drawings included in this specification may be exaggerated to emphasize a clearer explanation.

[0036] FIG. 1 is a cross-sectional view of a pouch film laminate according to the present invention.

[0037] FIG. 2 is an exploded assembly diagram of a secondary battery according to the present invention.

[0038]

[0039] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0040] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components in addition to the components mentioned.

[0041]

[0042] The present invention will be described in detail below.

[0043] The pouch film laminate, pouch-type battery case, and / or pouch-type secondary battery according to the present invention comprises at least one of the configurations disclosed below, and may comprise any combination of technically feasible configurations among the configurations below.

[0044]

[0045] Pouch film laminate

[0046] First, a pouch film laminate (1) according to the present invention will be described. FIG. 1 illustrates a pouch film laminate (1) according to the present invention.

[0047] Referring to FIG. 1, a pouch film laminate (1) according to the present invention may include a sequentially laminated substrate layer (10), a gas barrier layer (20), and a sealant layer (30), and the sealant layer (30) may include a first sealant layer (32) and a second sealant layer (34). In the pouch film laminate (1), the substrate layer (10), the gas barrier layer (20), the first sealant layer (32), and the second sealant layer (34) may be laminated in order.

[0048] In the conventional manufacturing of pouch film laminates, a lubricant was present on the surface of the sealant layer by methods such as including a lubricant in the innermost sealant layer of the pouch film or applying a lubricant to the surface of the sealant layer in order to prevent adhesion between pouch film laminates and to facilitate subsequent processing. However, there was a problem in that the molding die was contaminated by the lubricant on the surface of the sealant layer, requiring frequent cleaning, which reduced processability.

[0049] However, when the second sealant layer is composed of polypropylene (PP) modified with siloxane having a weight-average molecular weight of 100,000 to 500,000 as in the present invention, physical properties can be maintained even at high temperatures due to the heat-resistant properties of siloxane, and the strong bonding of the siloxane structure increases resistance to wear, thereby improving the durability of the modified polypropylene (PP) and maintaining stable performance in various environments, thus enabling the production of a pouch film laminate with superior processability and moldability compared to cases where a lubricant is included or applied.

[0050]

[0051] Hereinafter, each configuration of the pouch film laminate according to the present invention will be described in more detail with reference to FIG. 1.

[0052]

[0053] (1) Base layer

[0054] The substrate layer (10) is disposed on the outermost layer of the battery case to protect the electrode assembly from external shock and to electrically insulate it, and the substrate layer (10) may include one or more of polyethylene terephthalate (PET) and nylon.

[0055] According to one embodiment, the substrate layer (10) may be 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 positioned toward the gas barrier layer (20), i.e., toward the inside, and the polyethylene terephthalate film (12) is positioned toward the surface of the battery case.

[0056] Polyethylene terephthalate (PET) has excellent durability and electrical insulation properties, so when a PET film is placed on the surface side, excellent durability and insulation properties are exhibited. However, in the case of a PET film, the adhesion to the aluminum alloy thin film constituting the gas barrier layer (20) is weak and the stretching behavior is different. Therefore, when a PET film is placed on the gas barrier layer side, delamination between the substrate layer and the gas barrier layer may occur during the molding process, and the gas barrier layer may not be stretched uniformly, resulting in a decrease in moldability. In contrast, since a nylon film has a stretching behavior similar to that of the aluminum alloy thin film constituting the gas barrier layer (20), an improvement in moldability can be obtained when a nylon film is placed between the polyethylene terephthalate and the gas barrier layer.

[0057] The thickness of the above substrate layer (10) may be 5㎛ to 70㎛, specifically 7㎛ to 65㎛, more specifically 10㎛ to 60㎛. When the above range is satisfied, excellent formability and rigidity after molding may be exhibited.

[0058] In addition, when the substrate layer (10) is a laminated structure of a polyethylene terephthalate (PET) film (12) and a nylon film (14), the polyethylene terephthalate film may have a thickness of 5 µm to 30 µm, specifically 7 µm to 30 µm, more specifically 10 µm to 15 µm, and the nylon film may have a thickness of 10 µm to 60 µm, specifically 10 µm to 55 µm, more specifically 15 µm to 40 µm. When the thicknesses of the polyethylene terephthalate film and the nylon film satisfy the above ranges, excellent moldability and rigidity after molding may be exhibited.

[0059]

[0060] (2) Gas barrier layer

[0061] The gas barrier layer (20) is laminated between the substrate layer (10) and the sealant layer (30) to secure the mechanical strength of the pouch, block the entry and exit of gas or moisture from outside the secondary battery, and prevent leakage of electrolyte from inside the pouch-type battery case.

[0062] The gas barrier layer (20) may be formed of metal. For example, the gas barrier layer may be a metal thin film comprising one or more metals selected from the group consisting of aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti), and invar, but is not limited thereto.

[0063] According to one embodiment of the present invention, the gas barrier layer (20) may be formed from an aluminum alloy thin film. When the gas barrier layer (20) is formed using an aluminum alloy thin film, it is possible to secure mechanical strength of a predetermined level or higher, while also ensuring light weight, complementing electrochemical properties of the electrode assembly and electrolyte, and heat dissipation. The aluminum alloy thin film may contain elements other than aluminum (Al). For example, the aluminum alloy thin film may contain one or more selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0064] In another example, the gas barrier layer (20) may be formed from a stainless steel thin film. Specifically, the gas barrier layer (20) may be manufactured by forming and / or processing a stainless steel thin film. The gas barrier layer (20) formed from stainless steel has relatively low thermal conductivity, which is effective in preventing or delaying heat diffusion to other cells during thermal runaway, and has relatively high toughness, which can suppress the occurrence of cracks in the pouch during use of the pouch-type battery. The stainless steel may include one or more elements other than iron (Fe), selected from the group consisting of copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0065] The thickness of the gas barrier layer (20) may be 20㎛ to 100㎛, specifically 30㎛ to 90㎛, and more specifically 40㎛ to 85㎛. Satisfying the above range is desirable in that it can properly block the entry and exit of gases or moisture, etc., from outside the secondary battery and properly prevent leakage of electrolyte from inside the pouch-type battery case. In addition, moldability and gas barrier performance can be improved when molding the cup portion.

[0066]

[0067] (3) Sealant layer

[0068] The sealant layer (30) is intended to completely seal the inside of the pouch-type battery case from the outside by mutually thermally bonding at the sealing portion (250) when the pouch-type battery case (210) that accommodates the electrode assembly on the inside is sealed. To this end, the sealant layer (30) may be formed of a material having excellent thermal bonding strength.

[0069] The sealant layer (30) may have a composite membrane structure formed by two or more materials forming layers. Specifically, the sealant layer (30) according to the present invention includes a first sealant layer (32) and a second sealant layer (34). In this case, the first sealant layer (32) is a layer disposed adjacent to the gas barrier layer (20), and the second sealant layer (34) is a layer disposed on the first sealant layer (32). The first sealant layer (32) and the second sealant layer (34) may each include materials with different materials and / or physical properties.

[0070] The thickness of the sealant layer (30) may be 30㎛ to 130㎛, preferably 40㎛ to 120㎛, and more preferably 60㎛ to 100㎛. When the thickness of the sealant layer satisfies the above range, it has the effect of ensuring the sealing strength of the sealing portion while also ensuring the moldability of the pouch film laminate.

[0071] The amount of lubricant present on the surface of the sealant layer (30) is 1 mg / m² 2 Less than, specifically 0.5 mg / m² 2The amount may be less than, and more specifically, may not include a lubricant. Even if the sealant layer according to the present invention includes a lubricant within the above range, it may separately include polypropylene (PP) modified with siloxane having a weight-average molecular weight of 100,000 to 500,000 in the second sealant layer (34), thereby exhibiting excellent slip and moldability, maintaining appropriate frictional force, and improving processability by extending the lubricant cleaning cycle as contamination of the molding die is reduced due to the small amount of lubricant.

[0072] The sealant layer (30) may have a friction coefficient of 0.05 or higher, specifically 0.1 or higher, more specifically 0.15 or higher, and 0.30 or lower, specifically 0.25 or lower, more specifically 0.22 or lower. When the above range is satisfied, the slip properties of the sealant layer are appropriately improved, so that even if physical deformation occurs in the sealant layer during molding, the occurrence of defects such as cracks is reduced and whitening can be reduced.

[0073]

[0074] Below, the first sealant layer (32) and the second sealant layer (34) described above will each be explained in more detail.

[0075]

[0076] 1) First sealant layer

[0077] The first sealant layer (32) is characterized by being positioned adjacent to the gas barrier layer (20) as described above.

[0078] The first sealant layer (32) may be formed from a polymer material. Specifically, the first sealant layer (32) may include one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber, and preferably may include a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may be composed of cast polypropylene (CPP), acid modified polypropylene (PPA), or a polypropylene-butylene-ethylene terpolymer. More preferably, the first sealant layer may include one or more selected from polypropylene (PP), acid-modified polypropylene (PPa), and unoriented polypropylene (CPP).

[0079] It is particularly preferable that the first sealant layer (32) includes acid-modified polypropylene (PPa) to ensure long-term adhesion performance between the gas barrier layer (20) and the first sealant layer (32).

[0080] The thickness of the first sealant layer (32) may be 10 to 100 μm, preferably 20 to 80 μm, and more preferably 30 to 50 μm. When the above range is satisfied, the sealing durability and insulation of the sealing part may be improved, and the sealing strength of the sealing part may be improved due to excellent yield strength. In addition, the overall thickness of the pouch film laminate may not be excessively thick, thereby increasing moldability, and the space for accommodating the electrode assembly in the pouch-type battery case manufactured by molding the pouch film laminate may be increased, thereby improving the energy density relative to the volume of the secondary battery.

[0081]

[0082] 2) Second sealant layer

[0083] The second sealant layer (34) is characterized by being laminated on the first sealant layer (32) as described above.

[0084] The second sealant layer (34) may be formed from a material having insulating, corrosion-resistant, and sealing properties. Since the second sealant layer (34) comes into direct contact with the electrode assembly and / or electrolyte inside the receiving space, it may be formed from a material having insulating and corrosion-resistant properties. Additionally, since the second sealant layer (34) must completely seal the inside of the pouch-type battery case to block material transfer between the inside and outside, it may be formed from a material having high sealing properties (e.g., excellent thermal sealing strength).

[0085] The second sealant layer (34) may include one or more materials selected from the group consisting of polypropylene (PP) modified with siloxane, polypropylene (PP), polyethylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber, and specifically may include polypropylene (PP) modified with siloxane and polypropylene (PP). The polypropylene (PP) modified with siloxane has a structure in which siloxane is attached to the end of the branches of polypropylene (PP), and the siloxane branches are arranged on the surface of the second sealant layer, so that the coefficient of friction can be lowered due to electrical and chemical properties. Therefore, the siloxane-modified polypropylene (PP) described above improves the flexibility and processability of the second sealant layer, thereby reducing wrinkles and cracks that may occur during the molding of the pouch film laminate. Consequently, friction can be maintained even without applying a separate lubricant to the sealant layer. Consequently, unlike when a lubricant is used, contamination of the molding die is reduced, extending the cleaning cycle and resulting in excellent processability. Additionally, the defect rate caused by contamination is reduced, improving processability, preventing wrinkles during cup molding, and ensuring excellent maximum molding depth.

[0086] At this time, the siloxane-modified polypropylene (PP) may have a weight-average molecular weight of 100,000 or more, specifically 150,000 or more, more specifically 200,000 or more, and 500,000 or less, specifically 450,000 or less, more specifically 400,000 or less. If the weight-average molecular weight of the siloxane-modified polypropylene (PP) is less than 100,000, the mechanical strength decreases due to the low weight-average molecular weight, which weakens durability and ultimately reduces thermal stability, causing wrinkles to form during molding. If the weight-average molecular weight of the siloxane-modified polypropylene (PP) exceeds 500,000, the viscosity is high, making processing difficult, and consequently, there is a problem of difficulty in mixing with the polypropylene (PP) in the second sealant layer.

[0087] The above weight-average molecular weight may refer to a converted value for standard polystyrene measured by gel permeation chromatography (GPC), and unless otherwise specifically defined, the molecular weight may refer to the weight-average molecular weight. For example, in the present invention, the weight-average molecular weight is measured using the Agilent 1200 series, and the column used may be an Agilent PL mixed B column, and the solvent may be tetrahydrofuran (THF).

[0088] The second sealant layer may contain siloxane-modified polypropylene (PP) in an amount of 10% to 70% by weight, specifically 30% to 65% by weight, and more specifically 45% to 55% by weight, based on the total weight of the second sealant layer. When the weight ratio of the siloxane-modified polypropylene (PP) satisfies the above range, the slip properties of the siloxane-modified polypropylene (PP) generate appropriate frictional force, thereby preventing the blocking phenomenon where the pouch film laminates stick together during manufacturing.

[0089] The thickness of the second sealant layer (34) may be 10㎛ or more, preferably 15㎛ or more, 20㎛ or more, 25㎛ or more, or 30㎛ or more, 80㎛ or less, 75㎛ or less, 70㎛ or less, 65㎛ or less, or 60㎛ or less, and more preferably 30㎛ to 60㎛. When the thickness of the second sealant layer satisfies the above range, it is possible to secure the sealing strength of the sealing portion while also securing the moldability of the pouch film laminate.

[0090]

[0091] The pouch film laminate according to the present invention as described above can be manufactured through a method for manufacturing a pouch film laminate known in the art. For example, the pouch film laminate according to the present invention can be manufactured by a method in which a substrate layer (10) is attached to the upper surface of a gas barrier layer (20) through an adhesive, a sealant layer (30) is formed on the lower surface of the gas barrier layer (20) through co-extrusion or an adhesive layer, and a silicone-based release coating layer (40) is coated on the lower surface of the sealant layer (30) through heat treatment, or by a method such as dry lamination or sandwich lamination. However, the method for manufacturing the pouch film laminate is not limited thereto.

[0092]

[0093] The thickness of the pouch film laminate according to the present invention may be 120㎛ to 300㎛, specifically 130㎛ to 280㎛, and more specifically 140㎛ to 200㎛. When the thickness of the pouch film laminate satisfies the above range, the molding depth can be increased while minimizing the reduction in the battery receiving space and the decrease in sealing durability caused by the increase in the thickness of the pouch laminate.

[0094]

[0095] Pouch-type secondary battery

[0096] Next, a pouch-type secondary battery (200) according to the present invention will be described. FIG. 2 shows an exploded assembly diagram of a pouch-type secondary battery (200) according to the present invention.

[0097] As illustrated in FIG. 2, a pouch-type secondary battery (200) according to the present invention may include a pouch-type battery case (210) manufactured by molding the aforementioned pouch film laminate, 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), an electrode lead (280), an insulating part (290), and an electrolyte (not shown).

[0098] Hereinafter, each configuration of the pouch-type secondary battery according to the present invention will be described in more detail with reference to FIG. 2.

[0099]

[0100] (1) Pouch-type battery case

[0101] A pouch-type battery case (210) can be manufactured by molding a pouch film laminate according to the present invention as described above. The pouch-type battery case (210) can accommodate an electrode assembly (260) inside. Since the detailed configuration and physical properties of the pouch film laminate are the same as those described above, a detailed description is omitted.

[0102] The pouch film laminate can be drawn and stretched by means of a punch or the like to manufacture a pouch-type battery case (210). As a result, the pouch-type battery case (210) may include a cup portion (222) and a receiving portion (224). The receiving portion (224) is a place for accommodating an electrode assembly and may refer to a receiving space formed in the shape of a pocket inside the cup portion (222) as the cup portion (222) is formed.

[0103] According to one embodiment of the present invention, a pouch-type battery case (210) may include a first case (220) and a second case (230) as shown in FIG. 3. The first case (220) includes a receiving portion (224) capable of receiving an electrode assembly (260), and the second case (230) may cover the receiving portion (224) from above so that the electrode assembly (260) does not escape to the outside of the battery case (210). As shown in FIG. 3, the first case (220) and the second case (230) may be manufactured with one side connected to the other, but are not limited thereto and may be manufactured in various ways, such as being separated from each other and manufactured separately.

[0104]

[0105] 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 drawn and formed adjacent to each other in a single pouch film laminate. In this case, cup portions (222, 232) can be formed in the first case (220) and the second case (230) respectively, as shown in FIG. 3. After receiving an electrode assembly (260) in a receiving portion (224) provided in the cup portion (222) of the first case (220), a 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 receive the electrode assembly (260) from above. Accordingly, since two cup portions (222, 232) accommodate one electrode assembly (260), an electrode assembly (260) with a thicker thickness than when there is only one cup portion (222) can be accommodated. Additionally, since one corner of the secondary battery (200) is formed by folding the pouch-type battery case (210), the number of corners to be sealed can be reduced when performing a sealing process later. Accordingly, the processing speed of the pouch-type secondary battery (200) can be improved and the number of sealing processes can be reduced.

[0106] The pouch-type battery case (210) can be sealed while accommodating the electrode assembly (260) so that a part of the electrode lead (280), which will be described later, i.e., the terminal part, is exposed. Specifically, when the electrode lead (280) is connected to the electrode tab (270) of the electrode assembly (260) and an insulating part (290) is formed on a part of the electrode lead (280), the electrode assembly (260) is accommodated in the receiving part (224) provided in the cup part (222) of the first case (220), and the second case (230) can cover the receiving part (224) from above. Subsequently, an electrolyte is injected into the interior of the receiving part (224), and the sealing part (250) formed on the edges of the first case (220) and the second case (230) can be sealed.

[0107] The sealing portion (250) can perform the function of sealing the receiving portion (224). Specifically, the sealing portion (250) can seal the receiving portion (224) by being formed along the edge of the receiving portion (224). The temperature at which the sealing portion (250) is sealed may be 180°C to 250°C, specifically 200°C to 250°C, and more specifically 210°C to 240°C. When the sealing temperature satisfies the above numerical range, the pouch-type battery case (210) can secure sufficient sealing strength by thermal bonding.

[0108]

[0109] (2) Electrode assembly

[0110] 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 is injected.

[0111] The electrode assembly (260) may be formed by sequentially stacking an anode, a separator, and a cathode. Specifically, the electrode assembly (260) may include two types of electrodes, an anode and a cathode, and a separator interposed between the electrodes to insulate them from one another.

[0112] The positive and negative electrodes may each have a structure in which an active material slurry is coated onto an electrode current collector in the form of a metal foil or metal mesh containing aluminum and copper. The slurry can typically be formed by stirring granular active material, an auxiliary conductor, a binder, and a conductive material with added solvent. The solvent can be removed in a subsequent process.

[0113] An electrode assembly (260) can be manufactured in a predetermined shape by applying a slurry, which is a mixture of an electrode active material and a binder and / or a conductive material, to an anode current collector and a cathode current collector to manufacture an anode and a cathode, and stacking them on both sides of a separator. The types of electrode assemblies (260) may include stack type, jelly roll type, stack and folding type, etc., but are not limited thereto.

[0114] The electrode assembly (260) may include an electrode tab (270).

[0115] The electrode tab (270) is connected to the positive and negative electrodes of the electrode assembly (260), respectively, and protrudes outward from the electrode assembly (260), serving as a path for electrons to move between the inside and outside of the electrode assembly (260). The electrode current collector included in the electrode assembly (260) may be composed of a portion coated with an electrode active material and a terminal portion not coated with an electrode active material, i.e., a non-coated portion. The electrode tab (270) may be formed by cutting the non-coated portion or by connecting a separate conductive member to the non-coated portion using ultrasonic welding or the like. As shown in FIG. 2, the electrode tab (270) may protrude in different directions from the electrode assembly (260), but is not limited thereto and may be formed to protrude in various directions, such as protruding in parallel from one side in the same direction.

[0116]

[0117] (3) Electrode lead

[0118] 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.

[0119] The electrode lead (280) is connected to the electrode assembly (260) and can protrude to the outside of the pouch-type battery case (210) via the sealing portion (250). Specifically, one end of the electrode lead (280) is connected to the electrode assembly (260), specifically the electrode tab (270), and the other end of the electrode lead (280) can protrude to the outside of the pouch-type battery case (210).

[0120] The electrode lead (280) may include a positive lead (282) that has one end connected to a positive tab (272) and extends in the direction in which the positive tab (272) protrudes, and a negative lead (284) that has one end connected to a negative tab (274) and extends in the direction in which the negative tab (274) protrudes. Both the positive lead (282) and the negative lead (284) may have their other ends protruding to the outside of the battery case (210). Thus, electricity generated inside the electrode assembly (260) can be supplied to the outside. Additionally, since the positive tab (272) and the negative tab (274) are formed to protrude in various directions, the positive lead (282) and the negative lead (284) may also extend in various directions. The positive lead (282) and the negative lead (284) may have different materials. That is, the positive lead (282) is made of the same aluminum (Al) material as the positive current collector, and the negative lead (284) may be made of the same copper (Cu) material as the negative current collector or a copper material coated with nickel (Ni). A portion of the electrode lead (280) protruding outside the battery case (210) can be a terminal portion and electrically connected to an external terminal.

[0121]

[0122] (4) Insulating part

[0123] The insulating part (290) prevents electricity generated from the electrode assembly (260) from flowing to the battery case (210) through the electrode lead (280) and can maintain the sealing of the battery case (210). To this end, the insulating part (290) may be formed of a non-conductive insulating material that does not conduct electricity well. Generally, the insulating part (290) is often made of insulating tape or film that is easy to attach to the electrode lead (280) and has a relatively thin thickness, but is not limited thereto, and any material capable of insulating the electrode lead (280) may be used.

[0124] The insulating portion (290) may be positioned to surround the outer surface of the electrode lead (280). Specifically, at least a portion of the electrode lead (280) may be surrounded by the insulating portion (290). In this case, the insulating portion (290) may be positioned between the electrode lead (280) and the pouch-type battery case (210). The insulating portion (290) may be located in a sealing portion (250) where the first case (220) and the second case (230) of the pouch-type battery case (210) are heat-fused, and the electrode lead (280) may be bonded to the battery case (210).

[0125]

[0126] (5) Electrolyte

[0127] The pouch-type secondary battery (200) according to the present invention may further include an electrolyte injected into the inside of the pouch-type battery case (210). The electrolyte is intended to move lithium ions generated by the electrochemical reaction of the electrodes during the charging / discharging of the secondary battery (200), and may include a non-aqueous organic electrolyte, which is a mixture of a lithium salt and an organic solvent, or a polymer using a polymer electrolyte. Furthermore, the electrolyte may include a sulfide-based, oxide-based, or polymer-based solid electrolyte, and such a solid electrolyte may have flexibility that allows it to be easily deformed by an external force.

[0128]

[0129] The present invention will be explained in more detail below through specific embodiments. However, the following embodiments are merely examples to aid in understanding the invention and do not limit the scope of the invention. It is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of this description, and it is natural that such variations and modifications fall within the scope of the appended claims.

[0130]

[0131] Examples and Comparative Examples

[0132] Example 1: Manufacture of pouch film laminate

[0133] A first sealant layer with a total thickness of 40 μm was prepared by sequentially stacking acid-modified polypropylene (PPa) and polypropylene (PP), and a second sealant layer with a total thickness of 40 μm was laminated on the first sealant layer by including polypropylene (PP) modified with siloxane having a weight-average molecular weight of 300,000. At this time, the second sealant layer was prepared to include polypropylene (PP) modified with siloxane and polypropylene (PP) in a weight ratio of 50:50.

[0134] After that, a second adhesive film, a nylon film with a thickness of 25 μm, a first adhesive film, and a polyethylene terephthalate film with a thickness of 12 μm were sequentially laminated on one side of an aluminum alloy thin film with a thickness of 60 μm, and a sealant layer including the first sealant layer and the second sealant layer was sequentially laminated on the other side of the aluminum alloy thin film.

[0135] As a result, a pouch film laminate having a structure in which the second sealant layer / first sealant layer / aluminum alloy thin film / second adhesive film / nylon film / first adhesive film / polyethylene terephthalate film manufactured as above are sequentially laminated was manufactured.

[0136]

[0137] Example 2: Manufacture of pouch film laminate

[0138] A pouch film laminate was prepared in the same manner as in Example 1, except that siloxane-modified polypropylene (PP) with a weight-average molecular weight of 100,000 was used.

[0139]

[0140] Example 3: Manufacture of pouch film laminate

[0141] A pouch film laminate was prepared in the same manner as in Example 1, except that a second sealant layer was prepared such that the weight ratio of siloxane-modified polypropylene (PP) to polypropylene (PP) was 70:30.

[0142]

[0143] Example 4: Manufacture of pouch film laminate

[0144] A pouch film laminate was manufactured in the same manner as in Example 1, except that the thickness of the second sealant layer was 10 μm.

[0145]

[0146] Example 5: Preparation of pouch film laminate

[0147] A pouch film laminate was manufactured in the same manner as in Example 1, except that the thickness of the second sealant layer was 8 μm.

[0148]

[0149] Example 6: Preparation of pouch film laminate

[0150] A pouch film laminate was manufactured in the same manner as in Example 1, except that the thickness of the second sealant layer was 60 μm.

[0151]

[0152] Comparative Example 1: Manufacture of pouch film laminate

[0153] A pouch film laminate was prepared in the same manner as in Example 1, except that polydimethylsiloxane (PDMS) was used instead of siloxane-modified polypropylene (PP).

[0154]

[0155] Comparative Example 2: Manufacture of pouch film laminate

[0156] A pouch film laminate was prepared in the same manner as in Example 1, except that siloxane-modified polypropylene (PP) with a weight-average molecular weight of 80,000 was used.

[0157]

[0158] Comparative Example 3: Manufacture of pouch film laminate

[0159] A pouch film laminate was prepared in the same manner as in Example 1, except that siloxane-modified polypropylene (PP) with a weight-average molecular weight of 600,000 was used.

[0160]

[0161] Comparative Example 4: Manufacture of pouch film laminate

[0162] Without separately forming a second sealant layer, the amount of lubricant on the surface of the sealant layer is 4 mg / m² 2 A pouch film laminate was prepared in the same manner as in Example 1, except that a lubricant (erucamide) was applied.

[0163]

[0164] Comparative Example 5: Manufacture of pouch film laminate

[0165] Without separately forming a second sealant layer, the amount of lubricant on the surface of the sealant layer is 26 mg / m² 2 A pouch film laminate was prepared in the same manner as in Example 1, except that a lubricant (erucamide) was applied.

[0166]

[0167] Experimental Example 1: Measurement of Friction Coefficient

[0168] The friction coefficient of each pouch film laminate prepared according to Examples 1 to 6 and Comparative Examples 1 to 5 was measured.

[0169] As a method for measuring the coefficient of friction, a sled metal having dimensions of 130 mm (MD direction) x 65 mm (TD direction) and a weight of 200 g was brought into contact with a silicone-based release coating layer of a pouch film laminate having dimensions of 300 mm (MD direction) x 200 mm (TD direction) and measured.

[0170] Specifically, the sled metal was moved 100 mm over the sealant layer at a speed of 100 mm / min, and the friction coefficient was measured by taking the average value of the kinetic friction coefficients measured 5 times in the 20 mm to 80 mm section.

[0171] The measurement results are shown in [Table 1] below.

[0172]

[0173] Experimental Example 2: Evaluation of Pouch Film Laminate Formability

[0174] (1) Evaluation of mold depth

[0175] The moldability of each pouch film laminate prepared according to Examples 1 to 6 and Comparative Examples 1 to 5 was evaluated.

[0176] As a method for evaluating the formability of a pouch film laminate, the pouch film laminates were each cut to the same size of 300 mm (MD direction) × 400 mm (TD direction), and then the maximum forming depth at which no cracks occurred was recorded while varying the forming depth in a battery case forming device having two forming sections of size 61 mm (MD direction) × 159 mm (TD direction). Here, the punch and forming section of the battery case forming device were filleted at the corners and edges, and the corner of the punch had a curvature of 2 mm and the edge had a curvature of 0.5 mm, while the corner of the forming section had a curvature of 2.5 mm and the edge had a curvature of 1 mm. Additionally, the clearance between the punch and the forming section was 0.5 mm.

[0177] The measured molding depth is listed in [Table 1] below.

[0178]

[0179] (2) Evaluation of whether wrinkles occur

[0180] During the above evaluation of molding depth, when molding a pouch film with an uncontaminated molding device, it was evaluated as O if wrinkles occurred in the cup portion of the pouch film laminate at the maximum molding depth, and X if no wrinkles occurred.

[0181] Whether wrinkles occurred is indicated in [Table 1] below.

[0182]

[0183] Experimental Example 3: Measurement of Lubricant Cleaning Cycle During Pouch Film Laminate Forming

[0184] When molding each pouch film laminate prepared according to Examples 1 to 6 and Comparative Examples 1 to 5, the lubricant cleaning cycle was measured.

[0185] Specifically, the lubricant cleaning cycle was measured based on the maximum number of strokes without wrinkles when continuously producing a pouch film laminate with a cup portion formed at the maximum molding depth.

[0186] The measured results are listed in [Table 1] below.

[0187]

[0188] Experimental Example 4: Measurement of Sealing Strength

[0189] The sealing strength of each pouch film laminate prepared according to Examples 1 to 6 and Comparative Examples 1 to 5 was measured.

[0190] As a method for measuring the sealing strength of a pouch film laminate, the pouch film laminate was cut to a width of 266 mm and a length of 200 mm, then folded in half to a size of 133 mm × 200 mm so that a silicone-based release coating layer was in contact, and then the end of the long side (200 mm) was sealed for 1.6 seconds, 3 seconds, or 5 seconds, respectively, under conditions of a seal bar area of ​​200 mm × 8 mm, 200°C, and 0.1 MPa, thereby manufacturing a pouch-type battery case with a sealing portion formed thereon, and the sealing strength of the pouch-type battery case according to each sealing time was measured.

[0191] Specifically, the sealing strength was calculated from the maximum value of the tensile strength measured by cutting the sealing portion formed in the pouch-type battery case at 15mm intervals and pulling it in the 180° direction at a speed of 5mm / min at room temperature using a UTM.

[0192] Based on the calculated sealing strength, it was evaluated as O if the measured sealing strength was 10 kgf or more, and X if it was less than 10 kgf.

[0193] The evaluation results are listed in [Table 1] below.

[0194]

[0195] Coefficient of Friction Molding Depth [mm] Presence of Wrinkle Occurrence Detergent Cleaning Cycle [Other] Sealing Strength Example 10.28 x 8000 O Example 20.18 x 8000 O Example 30.168 x 8000 O Example 40.28 x 8000 O Example 50.25 x 7.5 x 8000 O Example 60.28 x 8000 O Comparative Example 10.35 x 6.5 x 8000 O Comparative Example 20.18 x 8000 O Comparative Example 30.46 x 8000 O Comparative Example 40.46 x 5000 O Comparative Example 50.05 x 8.0 O 500 O

[0196] Referring to Table 1 above, in the case of the pouch film laminates of Examples 1 to 6, in which the second sealant layer comprises polypropylene (PP) modified with siloxane having a weight-average molecular weight of 100,000 to 500,000, it can be seen that wrinkles do not occur during molding compared to the pouch film laminates of Comparative Examples 1 to 5, the lubricant cleaning cycle is also long, and the sealing strength is also excellent.

[0197]

[0198] [Explanation of the symbol]

[0199] 1: Pouch film laminate

[0200] 10: Base layer

[0201] 12: Polyethylene terephthalate film

[0202] 14: Nylon film

[0203] 20: Gas barrier layer

[0204] 30: Sealant layer

[0205] 32: 1st sealant layer

[0206] 34: Second sealant layer

[0207] 200: Pouch-type secondary battery

[0208] 210: Pouch-type battery case

[0209] 220: First case

[0210] 222: Cups

[0211] 224: Reception Department

[0212] 230: Second case

[0213] 232: Cups

[0214] 240: Bridge section

[0215] 250: Sealing part

[0216] 260: Electrode assembly

[0217] 270: Electrode tab

[0218] 272: Positive tab

[0219] 274: Cathode tab

[0220] 280: Electrode Lead

[0221] 282: Positive lead

[0222] 284: Cathode Lead

[0223] 290: Insulation part

Claims

1. A pouch film laminate comprising a sequentially laminated substrate layer, a gas barrier layer, and a sealant layer, wherein The sealant layer comprises a first sealant layer disposed adjacent to the gas barrier layer and a second sealant layer laminated on the first sealant layer. The second sealant layer comprises polypropylene (PP) modified with siloxane, and The above siloxane-modified polypropylene (PP) is a pouch film laminate having a weight-average molecular weight of 100,000 to 500,000.

2. In Claim 1, The pouch film laminate comprising the second sealant layer containing 10% to 70% by weight of the siloxane-modified polypropylene (PP) based on the total weight of the second sealant layer.

3. In Claim 1, A pouch film laminate having a second sealant layer with a thickness of 10㎛ or more.

4. In Claim 1, The amount of lubricant present on the surface of the above sealant layer is 1 mg / m² 2 Pouch film laminate less than 5. In Claim 1, A pouch film laminate having a friction coefficient of the sealant layer of 0.05 to 0.

30.

6. In Claim 1, The above substrate layer is a pouch film laminate comprising one or more of polyethylene terephthalate (PET) and nylon.

7. In Claim 1, A pouch film laminate having a thickness of 5㎛ to 70㎛ of the substrate layer.

8. In Claim 1, The above gas barrier layer is a pouch film laminate comprising one or more metals selected from the group consisting of aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti), and Invar.

9. In Claim 1, A pouch film laminate having a gas barrier layer thickness of 20㎛ to 100㎛.

10. In Claim 1, The above first sealant layer comprises one or more types selected from polypropylene (PP), acid-modified polypropylene (PPa), and unoriented polypropylene (CPP), forming a pouch film laminate.

11. In Claim 1, A pouch film laminate having a sealant layer thickness of 30㎛ to 130㎛.

12. In Claim 1, A pouch film laminate having a thickness of 120㎛ to 300㎛.

13. A pouch-type battery case manufactured by drawing molding the pouch film laminate of Claim 1.

14. A pouch-type secondary battery comprising the pouch-type battery case of claim 13.

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