Soft film laminate and secondary battery

Abstract

The present disclosure relates to a pouch film laminate and a secondary battery including a pouch type battery case manufactured using the same. The pouch type film laminate according to the present disclosure includes a base layer, a gas barrier layer, and a sealant layer laminated in this order, in which the sealant layer has a melt viscosity of 1000 Pa.s to 3500 Pa.s as measured at 190 DEG C.

Description

Technical Field

[0001] The present disclosure relates to a flexible package laminate and a prismatic secondary battery manufactured by molding the flexible package laminate. Background Art

[0002] Secondary batteries are used not only for small products such as digital cameras, P-DVDs, MP3Ps, mobile phones, PDAs, portable game devices, power tools, and electric bicycles, but also for large products that require high output such as electric vehicles and hybrid vehicles, as well as energy storage devices for storing surplus generated power and renewable energy and backup energy storage devices. Types of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, lithium-ion polymer batteries, and the like.

[0003] A secondary battery can be manufactured by accommodating an electrode assembly in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are alternately laminated in a battery case, injecting an electrolytic solution into the battery case, and then sealing the battery case. According to the material of the case accommodating the electrode assembly, secondary batteries are classified into prismatic batteries, hard case batteries, and the like.

[0004] A prismatic secondary battery can be manufactured by performing a pressing process on a flexible flexible package laminate to form a cup portion, then accommodating the electrode assembly in the internal accommodation space of the cup portion and sealing the sealing portion. The flexible package laminate is formed of a plurality of layers in which a polymer film such as polyethylene terephthalate is laminated on one surface of a gas barrier layer of metal, and a sealant layer of a thermoplastic polyolefin-based resin is laminated on the other surface thereof. When sealing the prismatic battery case, the sealant layers are thermally joined to each other to form a sealing portion.

[0005] In recent years, as the capacity of prismatic secondary batteries has increased, the demand for flexible packages with excellent molding properties has also increased. Therefore, attempts are being made to improve the molding properties of flexible packages by increasing the thickness of the gas barrier layer. However, when the gas barrier layer is formed to be thick, a conventional sealant layer configuration may not ensure sufficient insulation, and as the total thickness of the flexible package increases, the sealant layer is not easily melted during sealing, resulting in poor sealing quality. Summary of the Invention

[0006] Technical Problem

[0007] One aspect of the present disclosure provides a prismatic battery including a flexible package laminate having a sealant layer with a specific melt viscosity at 190°C and having excellent sealing quality, and a battery case formed using the flexible package laminate.

[0008] Technical Solution

[0009] According to one aspect of the present disclosure, a soft package laminate is provided, which includes a base layer, a gas barrier layer, and a sealant layer laminated in sequence, wherein the melt viscosity of the sealant layer measured at 190 °C is 1000 Pa·s to 3500 Pa·s.

[0010] The melt viscosity of the sealant layer measured at 170 °C may be 1400 Pa·s to 4500 Pa·s, and the melt viscosity of the sealant layer measured at 210 °C may be 500 Pa·s to 2500 Pa·s.

[0011] The melt flow rate (MFR) of the sealant layer measured under the conditions of a temperature of 230 °C and a load of 2.16 kg may be 1 g / 10 min to 15 g / 10 min, 1.5 g / 10 min to 15 g / 10 min, or 5 g / 10 min to 15 g / 10 min.

[0012] The thickness of the sealant layer may be 30 μm to 130 μm, the thickness of the gas barrier layer may be 40 μm to 100 μm, and the thickness of the base layer may be 5 μm to 100 μm.

[0013] In addition, the base layer may include a first base layer and a second base layer disposed between the first base layer and the gas barrier layer, and the second base layer may include nylon. In this case, the second base layer may include nylon 6.

[0014] According to another aspect of the present disclosure, a pouch-type secondary battery is provided, which includes a pouch-type battery case accommodating an electrode assembly, wherein the pouch-type battery case includes a soft package laminate, the soft package laminate includes a base layer, a gas barrier layer, and a sealant layer laminated in sequence, and the melt viscosity of the sealant layer measured at 190 °C is 1000 Pa·s to 3500 Pa·s.

[0015] When the pouch-type battery case is sealed at 210 °C and 1.2 MPa for 1.6 seconds, the thickness of the sealant layer of the seal portion formed in the pouch-type battery case may be 54% to 86% of the thickness of the sealant layer of the soft package laminate.

[0016] Beneficial effects

[0017] The soft package laminate according to the present disclosure includes a sealant layer having a melt viscosity of 1000 Pa·s to 3500 Pa·s at 190°C. When the melt viscosity of the sealant layer at 190°C satisfies the above range, the flow characteristics of the sealant layer near the sealing temperature are improved to seal the sealing portion with a desired thickness within a predetermined production time, and the sealing strength of the soft package can be improved by performing sufficient sealing between the sealant layers. When the soft package type battery case manufactured using the soft package laminate according to the present disclosure is applied to a secondary battery, excellent safety is achieved because air leakage caused by a decrease in sealing strength and deterioration of insulation performance caused by a decrease in the thickness of the sealing portion are prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings attached to the specification illustrate preferred examples of the present disclosure by way of example and are used to further understand the technical concept of the present disclosure together with the detailed description of the present disclosure given below. Therefore, the present disclosure should not be construed only by the content in these drawings.

[0019] Figure 1 is an exploded assembly view showing a soft package type secondary battery according to the present disclosure. DETAILED DESCRIPTION

[0020] The advantages, features, and methods for realizing the same of the present disclosure will be clarified by the following embodiments described with reference to the drawings. However, the present disclosure may be implemented in different forms and should not be construed as limited to the embodiments set forth herein. However, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. In addition, the present disclosure is defined only by the scope of the claims. Throughout the specification, the same reference numerals denote the same elements.

[0021] Unless otherwise defined, all terms (including technical and scientific terms) used herein may be intended to have the meaning understood by those skilled in the art. In addition, unless clearly and explicitly defined otherwise in the description, terms defined in a common dictionary are not ideally or overly interpreted to have a formal meaning.

[0022] The techniques used herein are only for describing particular example embodiments and are not intended to limit the present disclosure. In this specification, unless otherwise stated, terms in the singular form may include the plural form. It will also be understood that when used in this specification, the terms "comprises" and / or "comprising" specify the presence of the stated components, but do not preclude the presence or addition of one or more other components.

[0023] In this specification, when a part is referred to as "comprising" an element, unless otherwise stated, this part does not exclude other elements, but may also include other elements.

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

[0025] In this specification, unless otherwise clearly stated, the expression "%" means wt%.

[0026] Soft package laminate

[0027] The soft package laminate according to the present disclosure includes a base layer, a gas barrier layer, and a sealant layer laminated in sequence, wherein the sealant layer has a melt viscosity of 1000 Pa·s to 3500 Pa·s measured at 190°C.

[0028] Hereinafter, each component of the soft package laminate of the present disclosure will be described in more detail.

[0029] (1) Base layer

[0030] The base layer is formed on the outermost layer of the soft package laminate to protect the secondary battery from external friction and collision. The base layer can be made of a polymer to electrically insulate the electrode assembly from the outside.

[0031] The base layer can be made of at least one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber. Preferably, the base layer can be made of polyethylene terephthalate (PET), nylon having abrasion resistance and heat resistance, or a combination of the foregoing materials.

[0032] The thickness of the base layer can be 5 μm to 100 μm, specifically, 7 μm to 70 μm, and more specifically, 25 μm to 60 μm. When the thickness of the base layer satisfies the above range, the insulation performance against the outside is excellent, and the entire soft package is not thick, so the energy density of the secondary battery can be excellent compared to the volume.

[0033] The base layer can have a single-layer film structure made of any one material. Alternatively, the base layer can have a composite film structure in which two or more materials are formed into layers respectively. In the composite film structure, an adhesive layer can be additionally formed between the respective layers.

[0034] Specifically, the base layer may include a first base layer and a second base layer. For example, the base layer may include a first base layer disposed on the outermost surface of the flexible package laminate and a second base layer disposed between the first base layer and the gas barrier layer. The first base layer may include at least one of polyester-based films such as polyethylene terephthalate and polybutylene terephthalate, but is not limited thereto. The second base layer may include at least one of polyamide-based films such as nylon 6, nylon (6,6), nylon MXD6, and nylon (4,10), but is not limited thereto. Preferably, the second base layer may include nylon 6, and in this case, due to the excellent stretching properties of nylon 6, there is an advantage of improving the molding performance of the flexible package.

[0035] (2) Gas barrier layer

[0036] The gas barrier layer is laminated between the base layer and the sealant layer to ensure the mechanical strength of the flexible package, block all gases, moisture, etc. from the outside of the secondary battery, and prevent the electrolyte from leaking from the inside of the flexible package battery case.

[0037] The gas barrier layer may be formed of a metal. For example, the gas barrier layer may be a metal thin film including one or more metals selected from the group consisting of aluminum (Al), copper (Cu), stainless steel (SUS), nickel, titanium, and invar (INVAR).

[0038] According to an embodiment of the present disclosure, the gas barrier layer may be formed of an aluminum alloy thin film. When the gas barrier layer is formed by using an aluminum alloy thin film, due to the electrode assembly and the electrolyte, the gas barrier layer can be lighter while ensuring at least a predetermined level of mechanical strength, and ensuring heat dissipation performance, supplementing electrochemical performance, etc. The aluminum alloy thin film may include metal elements other than aluminum (Al), for example, at least one selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0039] The thickness of the gas barrier layer may be 40 μm to 100 μm, specifically, 50 μm to 90 μm, and more specifically, 55 μm to 85 μm. When the thickness of the gas barrier layer satisfies the above range, the molding performance and gas barrier performance are excellent when forming the cup portion.

[0040] (3) Sealant layer

[0041] The function of the sealant layer is to completely seal the inside of the flexible package battery case from the outside. When sealing the flexible package battery case containing the electrode assembly, the sealant layers are thermally joined to each other at the sealing portion. For this purpose, the sealant layer may be formed of a material having excellent thermal joining strength.

[0042] The sealant layer can be formed of a material having insulation properties, corrosion resistance, and sealing properties. Specifically, since the sealant layer is in direct contact with the electrode assembly and / or electrolyte inside the pouch-type battery case, the sealant layer can be formed of a material having insulation properties and corrosion resistance. Additionally, since the sealant layer must completely seal the inside of the pouch-type battery case to prevent substances from moving between the inside and the outside, the sealant layer can be formed of a material having high sealing performance (e.g., excellent thermal bonding strength). To ensure such insulation, corrosion resistance, and sealing performance, the sealant layer can be formed of a polymer material.

[0043] Meanwhile, when the gas barrier layer is formed thick to manufacture a pouch having good formability, there is a limitation that the sealant layer is not easily melted when sealing the pouch-type battery case. To solve this limitation, when the sealing temperature is increased to 220 °C or higher, there is a limitation in the melting and deformation of the base layer.

[0044] As a result of extensive and repeated research to solve this limitation, the inventors found that by controlling the melt viscosity of the sealant layer of the pouch film laminate within a specific numerical range, the thermal bonding between the sealant layers can proceed smoothly, the sealing strength of the pouch can be improved, and the sealed portion can be sealed to a desired thickness within a predetermined production time, thereby completing the present disclosure.

[0045] In the present disclosure, the melt viscosity of the sealant layer measured at 190 °C can be from 1000 Pa·s to 3500 Pa·s, specifically, from 1000 Pa·s to 3000 Pa·s, and more specifically, from 1200 Pa·s to 3000 Pa·s. When the melt viscosity of the sealant layer measured at 190 °C is less than 1000 Pa·s, there is a limitation that the sealant layer is excessively melted during pouch sealing, thereby reducing the remaining thickness of the sealant layer included in the sealed portion and damaging the insulation. When the melt viscosity of the sealant layer measured at 190 °C is greater than 3500 Pa·s, there is a limitation that the sealant layer is not sufficiently melted during pouch sealing, so that the sealing performed by the thermal bonding between the sealant layers cannot be sufficiently carried out, thereby reducing the sealing strength.

[0046] The melt viscosity of the sealant layer measured at 170 °C can be from 1400 Pa·s to 4500 Pa·s, specifically, from 1400 Pa·s to 4000 Pa·s, and more specifically, from 1800 Pa·s to 4000 Pa·s. When the melt viscosity of the sealant layer measured at 170 °C satisfies the above numerical range, the sealed portion can be sealed to a desired thickness within a predetermined production time.

[0047] The melt viscosity of the sealant layer measured at 210 °C can be from 500 Pa·s to 2500 Pa·s, specifically, from 800 Pa·s to 2500 Pa·s, and more specifically, from 800 Pa·s to 2000 Pa·s. When the melt viscosity of the sealant layer measured at 210 °C satisfies the above numerical range, the seal portion can be sealed to a desired thickness within a predetermined production time.

[0048] The melt viscosity of the sealant layer can vary depending on the type and physical properties of the material constituting the sealant layer. For example, if a polyolefin-based copolymer is used to form the sealant layer, the melt viscosity can vary depending on the type and content of the unit monomers constituting the copolymer, the weight average molecular weight of the copolymer, etc.

[0049] Meanwhile, in the present disclosure, the melt flow rate (MFR) of the sealant layer measured under the conditions of a temperature of 230 °C and a load of 2.16 kg can be from 1 g / 10 min to 15 g / 10 min, from 1.5 g / 10 min to 15 g / 10 min, from 5 g / 10 min to 15 g / 10 min, from 6 g / 10 min to 15 g / 10 min, or from 6 g / 10 min to 14 g / 10 min. When the melt flow rate of the sealant layer satisfies this numerical range, the seal portion can be sealed to a desired thickness within a predetermined production time.

[0050] Meanwhile, the thickness of the sealant layer can be from 30 μm to 130 μm, specifically, from 50 μm to 120 μm, and more specifically, from 70 μm to 100 μm. When the thickness of the sealant layer satisfies the above range, there is an effect of ensuring the molding performance of the soft film laminate while ensuring the sealing strength of the seal portion.

[0051] Preferably, the thickness of the sealant layer can be greater than or equal to the thickness of the gas barrier layer. Specifically, the thickness of the sealant layer can be 1 to 1.5 times, 1.1 to 1.5 times, or 1.2 to 1.5 times the thickness of the gas barrier layer. This is because if the thickness of the sealant layer is thinner than the thickness of the gas barrier layer, the insulation property may deteriorate.

[0052] Meanwhile, the sealant layer can include, for example, polyolefin-based resins such as polyethylene, polypropylene, polybutene or their copolymers, polycarbonate-based resins, polyethylene terephthalate-based resins, polyvinyl chloride-based resins, acrylic polymers, polyacrylonitrile-based resins, polyimide-based resins, polyamide-based resins, cellulose-based resins, aramid-based resins, nylon-based resins, polyester-based resins, poly(p-phenylene benzobisoxazole), polyarylate-based resins, Teflon, glass fiber or their mixtures. Preferably, it can be made of a polyolefin-based resin. More preferably, the sealant layer can be composed of cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer and / or polypropylene-butene-ethylene terpolymer.

[0053] Meanwhile, the sealant layer according to the present disclosure may have a single-layer film structure made of any one material. Alternatively, the sealant layer may have a composite film structure formed by separately forming layers of two or more materials. Specifically, the sealant layer may include a first sealant layer and a second sealant layer. In this case, the first sealant layer may be a layer disposed adjacent to the gas barrier layer, and the second sealant layer may be a layer disposed on the first sealant layer. The first sealant layer and the second sealant layer may be made of materials having different qualities and physical properties. An interface may exist between the first sealant layer and the second sealant layer. This means that the first sealant layer and the second sealant layer are different layers and may be formed separately.

[0054] The first sealant layer may be made of acid-modified polypropylene (PPa) to ensure long-term adhesion performance between the gas barrier layer and the first sealant layer. Here, the acid-modified polypropylene may be maleic anhydride polypropylene (MAHPP).

[0055] The second sealant layer may be made of a material having insulation, corrosion resistance, and sealing properties. Specifically, since the second sealant layer is in direct contact with the electrode assembly ( Figure 1 160) and / or the electrolyte inside the accommodation space ( Figure 1 124), the second sealant layer may be formed of a material having insulation and corrosion resistance. In addition, since the second sealant layer needs to completely seal the inside of the battery case to prevent substances from moving between the inside and the outside, the second sealant layer may be formed of a material having high sealing performance. To ensure such insulation, corrosion resistance, and sealing performance, the second sealant layer may include, for example, polyolefin-based resins such as polyethylene, polypropylene, polybutene, or copolymers thereof, polycarbonate-based resins, polyethylene terephthalate-based resins, polyvinyl chloride-based resins, acrylic polymers, polyacrylonitrile-based resins, polyimide-based resins, polyamide-based resins, cellulose-based resins, aramid-based resins, nylon-based resins, polyester-based resins, poly(p-phenylene benzobisoxazole), polyarylate-based resins, Teflon, glass fiber, or mixtures thereof. Preferably, it may be made of a polyolefin-based resin. More preferably, the second sealant layer may be composed of cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butene-ethylene terpolymer.

[0056] Soft package secondary battery

[0057] Next, a pouch-type secondary battery according to the present disclosure will be described.

[0058] The pouch-type secondary battery according to the present disclosure includes a pouch-type battery case that houses an electrode assembly. The pouch-type battery case includes a pouch film laminate, and the pouch film laminate includes a base layer, a gas barrier layer, and a sealant layer laminated in this order. The sealant layer has a melt viscosity of 1000 Pa·s to 3500 Pa·s measured at 190°C.

[0059] Hereinafter, each component of the pouch-type secondary battery of the present disclosure will be described in more detail with reference to the drawings.

[0060] Figure 1 is an exploded assembly view showing the pouch-type secondary battery 100 according to the present disclosure. As Figure 1 shown, the pouch-type secondary battery 100 according to the present disclosure may include a pouch-type battery case 110, an electrode assembly 160, electrode leads 180, an insulating part 190, and an electrolytic solution (not shown).

[0061] (1) Pouch-type battery case

[0062] The pouch-type battery case 110 can house the electrode assembly 160 therein. The pouch-type battery case 110 can be manufactured by molding the above-described pouch film laminate of the present disclosure. The detailed configuration and physical properties of the pouch film laminate are the same as those described above, and thus their detailed description will be omitted.

[0063] The pouch film laminate can be stretched and molded by a punch or the like to manufacture the pouch-type battery case 110. Accordingly, the pouch-type battery case 110 may include a cup part 122 and a housing part 124. The housing part 124 is a position for housing the electrode assembly, and may refer to a housing space formed in a bag shape inside the cup part 122 when the cup part 122 is formed.

[0064] According to an embodiment of the present disclosure, as Figure 1 shown, the pouch-type battery case 110 may include a first case 120 and a second case 130. The first case 120 may include a housing part 124 capable of housing the electrode assembly 160, and the second case 130 may cover the housing part 124 from above so that the electrode assembly 160 does not escape from the battery case 110. As Figure 1 shown, the first case 120 and the second case 130 may be manufactured by connecting one side of them to each other, but are not limited thereto, and may be manufactured in various ways, for example, manufactured separately.

[0065] According to another embodiment of the present disclosure, when forming the cup part on the pouch film laminate, two cup parts 122 and 132 symmetric to one pouch film laminate may be drawn adjacent to each other. In this case, as Figure 1As shown, cup portions 122 and 132 may be formed in the first housing 120 and the second housing 130, respectively. After the electrode assembly 160 is received in the receiving portion 124 provided in the cup portion 122 of the first housing 120, the bridging portion 140 formed between the two cup portions 122 and 132 may be folded such that the two cup portions 122 and 132 face each other. In this case, the cup portion 132 of the second housing 130 may receive the electrode assembly 160 from above. Therefore, since two cup portions 122 and 132 receive one electrode assembly 160, an electrode assembly 160 having a thickness greater than that of the electrode assembly received in one cup portion 122 may be received. In addition, since one edge of the secondary battery 100 is formed by folding the pouch-type battery case 110, the number of edges to be sealed may be reduced when a subsequent sealing process is performed. Accordingly, the process speed of the pouch-type secondary battery 100 may be increased and the number of sealing processes may be reduced.

[0066] The pouch-type battery case 110 may be sealed in a state in which the electrode assembly 160 is received, and a part of the electrode lead 180, that is, its terminal portion described below, may be exposed. Specifically, when the electrode lead 180 is connected to the electrode tab 170 of the electrode assembly 160 and the insulating portion 190 is formed on a part of the electrode lead 180, the electrode assembly 160 may be received in the receiving portion 124 provided in the cup portion 122 of the first housing 120, and the second housing 130 may cover the receiving portion 124 from above. Then, the electrolyte may be injected into the receiving portion 124, and the sealing portion 150 formed on the edges of the first housing 120 and the second housing 130 may be sealed.

[0067] The sealing portion 150 may be used to seal the receiving portion 124. Specifically, the sealing portion 150 may be formed along the edge of the receiving portion 124 to seal the receiving portion 124. The sealing temperature of the sealing portion 150 may 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 satisfies the above numerical range, the pouch-type battery case 110 may ensure sufficient sealing strength through thermal bonding.

[0068] According to the present disclosure, when the sealant layers of the first housing 120 and the second housing 130 are laminated to contact each other and then sealed at 210°C and 1.2 MPa for 1.6 seconds, the thickness of the sealant layer of the sealing portion 150 formed in the pouch-type battery case 110 may be 54% to 86%, specifically 55% to 85%, and more specifically 60% to 85% of the thickness of the sealant layer of the pouch film laminate. When the thickness of the sealant layer of the sealing portion 150 satisfies the above numerical range with respect to the thickness of the sealant layer of the pouch film laminate, sufficient sealing strength may be ensured and insulation performance may be maintained.

[0069] (2) Electrode assembly

[0070] The electrode assembly 160 can be inserted into the pouch-type battery case 110 and sealed by the pouch-type battery case 110 after an electrolyte is injected therein.

[0071] The electrode assembly 160 can be formed by sequentially laminating a positive electrode, a separator, and a negative electrode. Specifically, the electrode assembly 160 can include two electrodes, i.e., a positive electrode and a negative electrode, and a separator interposed between the positive electrode and the negative electrode and insulating the electrodes from each other.

[0072] The positive electrode and the negative electrode can each have a structure in which an active material paste is coated on an electrode current collector in the form of a metal foil or a metal mesh including aluminum and copper. The paste can generally be formed by stirring granular active materials, auxiliary conductors, binders, conductive agents, etc., while adding a solvent. The solvent can be removed in a subsequent process.

[0073] The paste obtained by mixing an electrode active material, a binder, and / or a conductive agent is coated on the positive electrode current collector and the negative electrode current collector to manufacture the positive electrode and the negative electrode, and the positive electrode and the negative electrode are respectively laminated on both sides of the separator, thereby manufacturing the electrode assembly 160 of a predetermined shape. The type of the electrode assembly 160 can be a laminated type, a wound type, a laminated and folded type, etc., but is not limited thereto.

[0074] The electrode assembly 160 can include electrode tabs 170.

[0075] The electrode tabs 170 can be respectively connected to the positive electrode and the negative electrode of the electrode assembly 160, can protrude from the electrode assembly 160 to the outside, and can be a path for electrons to move between the inside and the outside of the electrode assembly 160. The electrode current collector included in the electrode assembly 160 can be composed of a portion coated with the electrode active material and an end portion not coated with the electrode active material (i.e., a non-coated portion). The electrode tabs 170 can be formed by cutting the non-coated portion or by connecting a separate conductive member to the non-coated portion by ultrasonic welding or the like. As Figure 1 shown, the electrode tabs 170 can protrude from the electrode assembly 160 in different directions, but are not limited thereto, and can protrude in various directions. For example, they can protrude parallel from one side in the same direction.

[0076] (3) Electrode leads

[0077] The electrode leads 180 can supply power to the outside of the secondary battery 100. The electrode leads 180 can be connected to the electrode tabs 170 of the electrode assembly 160 by spot welding or the like.

[0078] The electrode lead 180 can be connected to the electrode assembly 160 and can protrude to the outside of the pouch-type battery case 110 via the sealing part 150. Specifically, one end of the electrode lead 180 can be connected to the electrode assembly 160, particularly, the electrode tab 170, and the other end of the electrode lead 180 can protrude to the outside of the pouch-type battery case 110.

[0079] The electrode lead 180 can include: a positive electrode lead 182, one end of the positive electrode lead 182 is connected to the positive electrode tab 172 and extends in the direction in which the positive electrode tab 172 protrudes; and a negative electrode lead 184, one end of the negative electrode lead 184 is connected to the negative electrode tab 174 and extends in the direction in which the negative electrode tab 174 protrudes. Both the positive electrode lead 182 and the negative electrode lead 184 can have the other end protruding to the outside of the battery case 110. Thus, the electric power generated inside the electrode assembly 160 can be supplied to the outside. Additionally, since each of the positive electrode tab 172 and the negative electrode tab 174 is formed to protrude in various directions, each of the positive electrode lead 182 and the negative electrode lead 184 can also extend in various directions. The materials of the positive electrode lead 182 and the negative electrode lead 184 can be different from each other. That is, the positive electrode lead 182 can be made of the same aluminum (Al) material as the positive electrode current collector, and the negative electrode lead 184 can be made of the same (Cu) material as the negative electrode current collector or a copper material coated with nickel (Ni). A part of the electrode lead 180 protruding to the outside of the battery case 110 can become a terminal part and can be electrically connected to an external terminal.

[0080] (4) Insulating part

[0081] The insulating part 190 prevents the electric power generated from the electrode assembly 160 from flowing to the battery case 110 through the electrode lead 180 and can maintain the seal of the battery case 110. To this end, the insulating part 190 can be formed of a non-conductor having non-conductivity through which current does not flow. Generally, the insulating part 190 is easily attached to the electrode lead 180, and a relatively thin insulating tape or insulating film is widely used as the insulating part, but the present disclosure is not limited thereto, and any member capable of insulating the electrode lead 180 can be used.

[0082] The insulating part 190 can be arranged to surround the outer peripheral surface of the electrode lead 180. Specifically, at least a part of the electrode lead 180 can be surrounded by the insulating part 190. In this case, the insulating part 190 can be arranged between the electrode lead 180 and the pouch-type battery case 110. The insulating part 190 can be restricted within the sealing part 150 where the first case 120 and the second case 130 of the pouch-type battery case 110 are heat-sealed, and the electrode lead 180 can be attached to the battery case 110.

[0083] (5) Electrolyte

[0084] The pouch-type secondary battery 100 according to the present disclosure may further include an electrolyte (not shown) injected into the pouch-type battery case 110. The electrolyte is used to move lithium ions generated by an electrochemical reaction through the electrodes during charging and discharging of the secondary battery 100, and may include a non-aqueous organic electrolyte that is a mixture of a lithium salt and an organic solvent or a polymer using a polymer electrolyte. In addition, the electrolyte may include: a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a polymer-based solid electrolyte, and the solid electrolyte may have flexibility that is easily deformed by an external force.

[0085] Meanwhile, when pressure is applied due to an external force or gas generation, peeling may occur at the interface of the sealed battery case 110, which has relatively weak adhesion. For example, peeling may occur along the interface between the heat-sealing adhesive layers. However, in the case of the battery case manufactured from the pouch film laminate of the present disclosure, since heat bonding between the sealant layers having improved flow characteristics during melting is performed smoothly, the adhesion at the interface remains high, thus having excellent sealing strength.

[0086] Embodiments of the present disclosure

[0087] Hereinafter, the present disclosure will be described in more detail with reference to specific examples. However, the following examples are only for illustrative purposes of the present disclosure, and the scope of the present disclosure 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 present disclosure. Such modifications and changes fall within the scope of the claims included herein.

[0088] Examples and comparative examples

[0089] Example 1

[0090] (1) Preparation of the pouch film laminate

[0091] A first adhesive film with a width of 266 mm, a length of 50 m, and a thickness of 3 μm; a nylon film with a width of 266 mm, a length of 50 m, and a thickness of 25 μm; a second adhesive film with a width of 266 mm, a length of 50 m, and a thickness of 3 μm; and a polyethylene terephthalate (PET) film with a width of 266 mm, a length of 50 m, and a thickness of 12 μm are sequentially laminated on one surface of an aluminum alloy film with a width of 266 mm, a length of 50 m, and a thickness of 60 μm. Next, a polypropylene-ethylene-butene copolymer resin with a weight average molecular weight of 380,000 g / mol and a weight ratio of propylene:ethylene:butene of 87:9:4 is extruded onto the other surface of the aluminum alloy film to form a sealant layer with a width of 266 mm, a length of 50 m, and a thickness of 80 μm, thereby preparing a soft package laminate.

[0092] (2) Preparation of the soft package type battery case

[0093] The soft package laminate prepared by the above method is cut into a width of 266 mm and a length of 200 mm, and then folded in half into a size of 133 mm × 200 mm so that the sealant layers are in contact with each other, and then the ends of the long side (200 mm) are sealed for 1.6 seconds under the conditions of a seal strip area of 200 mm × 8 mm, 210 °C, and 1.2 MPa, thereby preparing a soft package type battery case with a sealed portion formed.

[0094] Example 2

[0095] A soft package laminate and a soft package type battery case are prepared in the same manner as in Example 1, except that a polypropylene-ethylene-butene copolymer resin with a weight average molecular weight of 360,000 g / mol and a weight ratio of propylene:ethylene:butene of 92:7:1 is used to form the sealant layer.

[0096] Example 3

[0097] A soft package laminate and a soft package type battery case are prepared in the same manner as in Example 1, except that a polypropylene-ethylene-butene copolymer resin with a weight average molecular weight of 330,000 g / mol and a weight ratio of propylene:ethylene:butene of 79:11:10 is used to form the sealant layer.

[0098] Example 4

[0099] A soft package laminate and a soft package type battery case are prepared in the same manner as in Example 1, except that a polypropylene-ethylene copolymer resin with a weight average molecular weight of 440,000 g / mol and a weight ratio of propylene:ethylene of 97:3 is used to form the sealant layer.

[0100] Comparative Example 1

[0101] A soft package laminate and a soft package type battery case were prepared in the same manner as in Example 1, except that a polypropylene-ethylene-butene copolymer resin having a weight average molecular weight of 430,000 g / mol and a weight ratio of propylene:ethylene:butene of 94:4:2 was used to form the sealant layer.

[0102] Comparative Example 2

[0103] A soft package laminate and a soft package type battery case were prepared in the same manner as in Example 1, except that a polypropylene-ethylene-butene copolymer resin having a weight average molecular weight of 310,000 g / mol and a weight ratio of propylene∶ethylene∶butene of 91∶3∶6 was used to form the sealant layer.

[0104] Experimental Example 1: Evaluation of the melting properties of the sealant layer

[0105] The melting properties of the sealant layer included in the soft package laminate prepared in each of Examples 1 to 4 and Comparative Examples 1 and 2 were measured.

[0106] Specifically, the soft package laminate was cut into a size of 5 cm × 30 cm and treated with 37 wt% hydrochloric acid for 24 hours to remove the aluminum alloy film (gas barrier layer). The polymer film (sealant layer) containing polypropylene was separated, and then the soft package laminate was dried in a vacuum oven for 24 hours.

[0107] Three dried samples (3 g) were rolled into a column and placed in an MFR measuring device (MI-40, Gottfert GmbH), and the melt flow rate (MFR) was measured with a measuring section of 24.0 - 1.0 mm under the conditions of 230 °C and a load of 2.16 kg.

[0108] In addition, a rheometer (DHR-20, TA Instruments) was used to measure the melt viscosity of the separated polymer film (sealant layer) at three temperatures of 170 °C, 190 °C, and 210 °C in the frequency sweep mode. In this case, a 25 mm parallel plate was used to measure the geometry at a strain of 0.1% in the range of 0.1 to 100 Hz, and then the value at a shear rate of 3.5 s -1 was measured by Cox-Merz transformation.

[0109] The measurement results are shown in Table 1 below.

[0110] Experimental Example 2: Measurement of the thickness ratio of the sealant layer of the sealed part

[0111] The ratio (%) of the thickness of the sealant layer included in the sealed portion of the pouch-type casing prepared in each of Examples 1 to 4 and Comparative Examples 1 and 2 was calculated by measuring the thickness of the sealant layer.

[0112] Specifically, the thickness of the sealant layer included in the sealed portion was calculated by measuring the thickness of the sealed portion formed in the pouch-type battery casing at equal intervals of 9 points using a micrometer device, and then subtracting the thicknesses of the base layer and the gas barrier layer from the average value.

[0113] Thereafter, in Examples 1 to 4 and Comparative Examples 1 and 2, the ratio (%) of the thickness of the sealant layer of the sealed portion to the thickness (80 μm) of the sealant layer of the pouch film laminate was calculated, and the results are shown in Table 1 below.

[0114] Experimental Example 3: Evaluation of the sealing strength of the pouch-type battery casing

[0115] The sealing strength of the pouch-type battery casings prepared in each of Examples 1 to 4 and Comparative Examples 1 and 2 was measured.

[0116] Specifically, the sealed portion formed in the pouch-type battery casing was cut at intervals of 15 mm, and then the maximum value of the tensile strength was measured by stretching the sealed portion at a rate of 5 mm / min in the direction of 180° at room temperature using a UTM, and the sealing strength was calculated based on this maximum value. The results are shown in Table 1 below.

[0117] Experimental Example 4: Evaluation of the insulation resistance of the pouch-type battery casing

[0118] The insulation resistance of the pouch-type battery casings prepared in each of Examples 1 to 4 and Comparative Examples 1 and 2 was measured.

[0119] Specifically, the insulation resistance was measured by using a resistance meter (RM3544-01) device of HIOKI and detecting the resistance value for 5 seconds after applying 100 V. The measurement results are shown in Table 1 below.

[0120] [Table 1]

[0121]

[0122] According to Table 1, in the case of Examples 1 to 4 where the melt viscosity of the sealant layer measured at 190 °C satisfies 1000 Pa·s to 3500 Pa·s, it was confirmed that within the sealing time (1.6 seconds), a sealed portion having a thickness of 54% to 86% of the thickness of the sealant layer of the sealed portion based on the thickness of the sealant layer of the pouch film laminate was formed, the sealing strength was significantly higher than that of Comparative Example 1, and the insulation resistance was significantly higher than that of Comparative Example 2.

[0123]

Explanation of Reference Numerals of the Drawings

[0124] 100: Soft-pack secondary battery

[0125] 110: Soft-pack battery case

[0126] 120: First case

[0127] 122: Cup portion

[0128] 124: Accommodating portion

[0129] 130: Second case

[0130] 132: Cup portion

[0131] 140: Bridging portion

[0132] 150: Sealing portion

[0133] 160: Electrode assembly

[0134] 170: Electrode tab

[0135] 172: Positive electrode tab

[0136] 174: Negative electrode tab

Claims

1. A flexible packaging laminate, comprising a base layer, a gas barrier layer, and a sealant layer laminated in sequence, wherein, the melt viscosity of the sealant layer measured at 190 °C is 1000 Pa·s to 3500 Pa·s.

2. The flexible packaging laminate according to claim 1, wherein, the melt viscosity of the sealant layer measured at 170 °C is 1400 Pa·s to 4500 Pa·s.

3. The flexible packaging laminate according to claim 1, wherein, the melt viscosity of the sealant layer measured at 210 °C is 500 Pa·s to 2500 Pa·s.

4. The flexible packaging laminate according to claim 1, wherein, the melt flow rate of the sealant layer measured under the conditions of a temperature of 230 °C and a load of 2.16 kg, that is, MFR, is 1 g / 10 min to 15 g / 10 min.

5. The flexible packaging laminate according to claim 1, wherein, the thickness of the sealant layer is 30 μm to 130 μm.

6. The flexible packaging laminate according to claim 1, wherein, the thickness of the gas barrier layer is 40 μm to 100 μm.

7. The flexible packaging laminate according to claim 1, wherein, the thickness of the base layer is 5 μm to 100 μm.

8. The flexible packaging laminate according to claim 1, wherein, the base layer includes a first base layer and a second base layer provided between the first base layer and the gas barrier layer, and the second base layer includes nylon.

9. The flexible packaging laminate according to claim 8, wherein, the second base layer includes nylon 6.

10. A pouch-type secondary battery, comprising a pouch-type battery case containing an electrode assembly, wherein, the pouch-type battery case includes a flexible packaging laminate, the flexible packaging laminate includes a base layer, a gas barrier layer, and a sealant layer laminated in sequence, wherein the melt viscosity of the sealant layer measured at 190 °C is 1000 Pa·s to 3500 Pa·s.

11. The pouch-type secondary battery according to claim 10, wherein, when the pouch-type battery case is sealed at 210 °C and 1.2 MPa for 1.6 seconds, the thickness of the sealant layer of the seal portion formed in the pouch-type battery case is 54% to 86% of the thickness of the sealant layer of the flexible packaging laminate.

Images