Soft film laminate and secondary battery

Abstract

A soft envelope 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 gas barrier layer contains stainless steel and has a thickness of 50 [mu] m or more, and the thickness of the base layer is in the range of 10% to 30% of the thickness of the gas barrier layer.

Description

Technical Field

[0001] Cross - Reference to Related Applications

[0002] This application claims priority and the benefit of Korean Patent Application No. 10 - 2022 - 0182365, filed on December 22, 2022, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0004] The present disclosure relates to a soft - package laminate and a secondary battery manufactured by molding the soft - package laminate. Background Art

[0005] Generally, types of secondary batteries include nickel - cadmium batteries, nickel - metal hydride batteries, lithium - ion batteries, lithium - ion polymer batteries, etc. These secondary batteries are applied and used not only in small products such as digital cameras, P - DVDs, MP3Ps, mobile phones, PDAs, portable game devices, power tools, electric bicycles, etc., but also in large products that require high output such as electric vehicles or hybrid vehicles, as well as backup energy storage devices and energy storage devices for storing surplus generated electricity or renewable energy.

[0006] To manufacture such a secondary battery, first, an electrode active material slurry is coated on a positive electrode current collector and a negative electrode current collector to manufacture a positive electrode and a negative electrode, and then the positive electrode and the negative electrode are laminated on both sides of a separator to form an electrode assembly having a predetermined shape. Then, the positive electrode assembly is accommodated in a battery case, and then electrolyte injection and sealing are performed.

[0007] Secondary batteries are classified into pouch - type secondary batteries and can - type secondary batteries according to the material of the case configured to accommodate the electrode assembly. The pouch - type secondary battery has a structure in which the electrode assembly is accommodated in a pouch made of a flexible polymer material. The can - type secondary battery has a structure in which the electrode assembly is accommodated in a case made of a material such as metal, plastic, etc.

[0008] A pouch serving as a case of a pouch - type secondary battery is manufactured by performing stamping on a flexible soft - package laminate to form a cup portion. Once the cup portion is formed, a secondary battery can be manufactured by accommodating the electrode assembly in the inner accommodation space of the cup portion and sealing the sealing portion.

[0009] Generally, a flexible package laminate is formed of multiple layers in which a base layer is laminated on one surface of a gas barrier layer made of metal and a sealant layer is laminated on the other surface of the gas barrier layer. In the case of an aluminum flexible package where aluminum is applied to the gas barrier layer, it has the advantages of being lightweight and capable of supplementing the electrochemical properties of the electrode assembly and the electrolyte, and ensuring heat dissipation performance while ensuring mechanical strength above a specific level. However, the aluminum flexible package has a problem of melting and deforming when the pressure and temperature inside the battery cell rise due to a flame or the like. Therefore, technologies for applying stainless steel instead of aluminum to the gas barrier layer to prevent deformation due to high temperature and high pressure are being developed. However, when stainless steel is applied to the metal barrier layer, there is a problem of deterioration of the plasticity of the flexible package. Summary of the Invention

[0010] Technical Problem

[0011] According to the present disclosure, there is provided a flexible package laminate and a flexible pouch-type secondary battery capable of improving plasticity while ensuring the insulation of a flexible package containing stainless steel.

[0012] Technical Solution

[0013] According to an embodiment of the present disclosure, the flexible package laminate includes a base layer, a gas barrier layer, and a sealant layer laminated in sequence, wherein the gas barrier layer contains stainless steel, the thickness of the gas barrier layer is 50 μm or more, and the thickness of the base layer is in the range of 10% to 30% of the thickness of the gas barrier layer.

[0014] The flexible package laminate according to the present disclosure may have a thickness of 200 μm or less.

[0015] According to the present disclosure, the thickness of the base layer may be in the range of 2.5% to 6.5% of the thickness of the flexible package laminate. Specifically, the thickness of the base layer may be in the range of 5 μm to 20 μm. In addition, the base layer may include polyethylene terephthalate (PET).

[0016] According to the present disclosure, the thickness of the gas barrier layer may be 50 μm to 100 μm, and the melting point of the gas barrier layer may be 1000 °C or more.

[0017] The stainless steel included in the gas barrier layer may contain chromium in an amount of 10% by weight to 20% by weight and may contain nickel in an amount of 5% by weight to 20% by weight.

[0018] According to another embodiment of the present disclosure, a pouch-type secondary battery includes a pouch-type battery case accommodating 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 sequence. The gas barrier layer contains stainless steel, the thickness of the gas barrier layer is 50 μm or more, and the thickness of the base layer is in the range of 10% to 30% of the thickness of the gas barrier layer.

[0019] Advantageous effects

[0020] The pouch film laminate according to the present disclosure is characterized in that the thickness of the gas barrier layer containing stainless steel is 50 μm or more, and the thickness of the base layer is in the range of 10% to 30% of the thickness of the gas barrier layer. When the above conditions are satisfied, the pouch film laminate can significantly improve the plasticity of the pouch film laminate while ensuring insulation and chemical resistance, thereby ensuring the forming depth of the pouch. Therefore, by using the pouch film laminate according to the present disclosure, it is easy to realize a large-area pouch-type battery applied to an electric vehicle. Description of the drawings

[0021] Figure 1 is a cross-sectional view of the pouch film laminate according to the present disclosure.

[0022] Figure 2 is an exploded perspective view of the pouch-type secondary battery according to the present disclosure. Detailed description of the embodiments

[0023] With reference to the embodiments described in detail below and the drawings, the advantages and features of the present disclosure and the methods for achieving them will become clear. However, the present disclosure can be implemented in various different forms and should not be construed as limited to the embodiments disclosed below. On the contrary, these embodiments are provided only to make the disclosure of the present disclosure thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art to which the present disclosure pertains. Therefore, the present disclosure is not limited only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same elements.

[0024] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this specification can be used with the meanings commonly understood by those skilled in the art to which the present disclosure pertains. Additionally, unless specifically and clearly defined, the terms defined in a common dictionary cannot be interpreted ideally or excessively.

[0025] The terms used in this specification are used to describe the embodiments of the present disclosure and are not intended to limit the present disclosure. In this specification, unless otherwise specifically stated in the context, the singular form also includes the plural form. When used in the specification, the terms "comprise" and / or "include" do not exclude the presence or addition of one or more other elements in addition to the elements mentioned.

[0026] In this specification, when a part is referred to as including a specific component, unless otherwise specifically stated to the contrary, this does not mean excluding other components, but rather that the part may also include other components.

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

[0028] In this specification, unless otherwise clearly stated, the symbol "%" represents weight percentage.

[0029] Soft film laminate

[0030] The soft film laminate according to the present disclosure includes a base layer, a gas barrier layer, and a sealant layer laminated in this order, wherein the gas barrier layer contains stainless steel and has a thickness of 50 μm or more, and the thickness of the base layer is in the range of 10% to 30% of the thickness of the gas barrier layer.

[0031] Figure 1 is a cross-sectional view of the soft film laminate 100 according to the present disclosure. As Figure 1 shown, in the soft film laminate 100, a base layer 110, a gas barrier layer 120, and a sealant layer 130 may be laminated in this order.

[0032] According to the present disclosure, the thickness of the base layer 110 may be in the range of 10% to 30%, specifically 10% to 20%, and more specifically 10% to 15% of the thickness of the gas barrier layer 120. When the thickness of the base layer 110 is less than 10% of the thickness of the gas barrier layer 120, there may be a problem that the chemical resistance and insulation of the soft package may deteriorate. When the thickness of the base layer 110 is greater than 30% of the thickness of the gas barrier layer 120, the overall thickness of the soft package may increase, thereby reducing the energy density with respect to the volume of the secondary battery.

[0033] When the thickness of the base layer 110 is in the range of 10% to 30% of the thickness of the gas barrier layer 120, the formability of the soft film laminate 100 may be more affected by the thickness of the gas barrier layer 120 rather than the thickness of the base layer 110. Therefore, in the present disclosure, the thickness of the gas barrier layer 120 may be 50 μm or more, so that the formability of the soft film laminate 100 including the thin base layer 110 can be ensured.

[0034] The thickness of the soft film laminate 100 may be 200 μm or less, specifically 100 μm to 200 μm, and more specifically 100 μm to 180 μm. When the thickness of the soft film laminate 100 satisfies the above range, the soft package cup portion can be easily formed while ensuring sufficient mechanical strength to withstand the internal pressure of the soft package.

[0035] Hereinafter, each component of the soft packaging laminate of the present disclosure will be described in more detail.

[0036] (1) Base layer

[0037] The base layer 110 is formed on the outermost layer of the soft packaging laminate 100 to protect the secondary battery from external friction and collision. The base layer 110 is made of a polymer such that the base layer 110 can electrically insulate the electrode assembly from the outside.

[0038] The base layer 110 may have a single-layer film structure made of any one material. On the contrary, the base layer 110 may have a composite film structure in which two or more materials form respective layers.

[0039] Specifically, the base layer 110 according to the present disclosure may include a first layer, a second layer, and / or an adhesive layer. In this case, the thickness of the base layer 110 refers to the total thickness of the first layer, the second layer, and / or the adhesive layer. The first layer may be disposed on the outermost layer of the soft packaging laminate, and the second layer may be disposed between the first layer and the gas barrier layer. The adhesive layer may be disposed between the first layer and the second layer or between the second layer and the gas barrier layer. The first layer, the second layer, and the adhesive layer may be made of different materials and / or materials having different physical properties. An interface may exist between the first layer, the second layer, and the adhesive layer. This means that the first layer, the second layer, and the adhesive layer are different layers and can be formed separately. At the same time, the base layer 110 may include only the adhesive layer without the first layer and the second layer. In this case, the adhesive layer may be disposed on the outermost layer of the soft packaging laminate.

[0040] The first layer may be a layer disposed on the outermost layer of the soft packaging laminate. In this case, the first layer may be used to prevent moisture from penetrating from the outside of the soft package. The first layer may be made of 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, poly(p-phenylene benzobisoxazole), polyarylate, Teflon, and glass fiber. Preferably, the first layer may include at least one polyester-based film such as polyethylene terephthalate, polybutylene terephthalate, etc. having wear resistance and heat resistance, but the present disclosure is not limited thereto. More preferably, when the first layer includes polyethylene terephthalate (PET), it is flexible and excellent in external insulation, which makes it easy to manufacture the first layer with a thin thickness.

[0041] As described above, the second layer may be a layer disposed between the first layer and the gas barrier layer 120. In this case, the second layer may be used to improve the plasticity of the soft package. The second layer may include at least one polyamide-based film such as nylon 6, nylon (6,6), nylon MXD6, and nylon (4,10), but the present disclosure is not limited thereto. Preferably, the second layer may include nylon 6. In this case, due to the excellent elongation characteristics of nylon 6, there is an advantage that the plasticity of the soft package can be improved.

[0042] The thickness of the base layer 110 may be in the range of 2.5% to 6.5%, specifically 3.0% to 6.5%, and more specifically 3.0% to 6.0% of the thickness of the soft package film laminate 100. When the ratio of the thickness of the base layer 110 to the thickness of the soft package film laminate 100 satisfies the above numerical range, the external insulation and chemical resistance of the soft package can be ensured, and since the overall thickness of the soft package is not thick, the energy density with respect to the volume of the secondary battery can also be excellent.

[0043] The thickness of the base layer 110 may be in the range of 5 μm to 30 μm, specifically 5 μm to 25 μm, and more specifically 5 μm to 20 μm. When the thickness of the base layer 110 satisfies the above range, since the total thickness of the soft package is not thick, the energy density with respect to the volume of the secondary battery can be excellent, and the external insulation and chemical resistance of the soft package can also be ensured.

[0044] (2) Gas barrier layer

[0045] The gas barrier layer 120 is laminated between the base layer 110 and the sealant layer 130 to ensure the mechanical strength of the soft package, block the entry of gas or moisture from the outside of the secondary battery, and prevent the leakage of the electrolyte from the inside of the soft package type battery case.

[0046] The gas barrier layer 120 according to the present disclosure contains stainless steel. Specifically, the gas barrier layer 120 can be manufactured by molding and / or processing a stainless steel thin film. The gas barrier layer 120 containing stainless steel has a relatively low thermal conductivity, so it effectively prevents or delays the diffusion of heat to other battery cells in the event of thermal runaway, and has relatively high toughness to suppress the occurrence of cracks in the soft package during the use of the soft package type battery.

[0047] In addition to iron (Fe), the stainless steel further contains one or more materials selected from the group consisting of copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), zinc (Zn), molybdenum (Mo), carbon (C), phosphorus (P), sulfur (S), and nitrogen (N).

[0048] Specifically, the stainless steel may contain chromium in an amount of 10% by weight to 20% by weight, specifically 16% by weight to 20% by weight, and more specifically 18% by weight to 20% by weight. When the above numerical range is satisfied, the stainless steel has excellent corrosion resistance.

[0049] In addition, the stainless steel may contain nickel in an amount of 5% by weight to 20% by weight, specifically 6% by weight to 15% by weight, and more specifically 8% by weight to 14% by weight. When the above numerical range is satisfied, the corrosion resistance of the stainless steel to neutral and weak acids can be further improved.

[0050] The gas barrier layer 120 according to the present disclosure may have a thickness of 50 μm or more, specifically 50 μm to 100 μm, and more specifically 60 μm to 85 μm. When the thickness of the gas barrier layer 120 is less than 50 μm, the gas barrier layer 120 cannot be uniformly stretched, so the elongation rate of the soft package laminate may decrease, thereby reducing the formability of the soft package and making it impossible to ensure a sufficient forming depth of the soft package cup portion. Therefore, there is a problem in that it is difficult to realize a large-area soft package type battery applied to an electric vehicle. In addition, when the thickness of the gas barrier layer 120 is less than 50 μm, there is a problem that the gas barrier performance of the gas barrier layer 120 may deteriorate.

[0051] The melting point of the gas barrier layer 120 may be 1000 °C or more, specifically 1200 °C to 1500 °C, and more specifically 1300 °C to 1450 °C. When the melting point of the gas barrier layer 120 satisfies the above numerical range, even when the temperature of the soft package type battery cell rises significantly due to thermal runaway, the structure of the soft package can be prevented from collapsing.

[0052] (3) Sealant layer

[0053] The sealant layer 130 is used to completely seal the inside of the soft package type battery case by performing thermal bonding at the sealing portion when sealing the soft package type battery case in which the electrode assembly is accommodated. For this purpose, the sealant layer 130 may be formed of a material having excellent thermal bonding strength.

[0054] The sealant layer 130 may be formed of a material having insulation, corrosion resistance, and sealing properties. Specifically, since the sealant layer 130 is in direct contact with the electrode assembly and / or the electrolyte inside the soft package type battery case, the sealant layer 130 may be formed of a material having insulation and corrosion resistance. In addition, since the sealant layer 130 must completely seal the inside of the soft package type battery case to prevent materials from moving between the inside and outside of the soft package type battery case, it may be formed of a material having high sealing performance (for example, excellent thermal bonding strength). To ensure such insulation, corrosion resistance, and sealing performance, the sealant layer 130 may be formed of a polymer material.

[0055] The sealant layer 130 can be made of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, poly(p-phenylene benzobisoxazole), polyarylate, Teflon, and glass fiber. Preferably, the sealant layer 130 can be made of a polyolefin-based resin such as, for example, polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene can consist of cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butene-ethylene terpolymer.

[0056] The thickness of the sealant layer 130 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, it has the effect of ensuring the plasticity of the soft film laminate while ensuring the sealing strength of the sealed portion.

[0057] Meanwhile, the sealant layer 130 according to the present disclosure can have a single-layer film structure made of any one material. On the contrary, the sealant layer 130 can have a composite film structure in which two or more materials form respective layers. Specifically, the sealant layer 130 can include a first sealant layer and a second sealant layer. In this case, the first sealant layer can be a layer disposed adjacent to the gas barrier layer, and the second sealant layer can be a layer disposed on the first sealant layer. The first sealant layer and the second sealant layer can be made of different materials and / or materials having different physical properties. There can be an interface 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 can be formed separately.

[0058] In order to ensure the long-term adhesion performance between the gas barrier layer and the sealant layer, particularly preferably, the first sealant layer is made of acid-modified polypropylene (PPa). Here, the acid-modified polypropylene can be maleic anhydride polypropylene (MAH PP).

[0059] The second sealant layer can be made of a material having insulation, corrosion resistance, and sealing properties. Specifically, since the second sealant layer is in contact with the electrode assembly ( Figure 2 inside the accommodation space ( Figure 2It is in direct contact with the separator 260) and / or the electrolyte, so it can be formed of a material having insulation and corrosion resistance. In addition, since the second sealant layer must completely seal the interior of the battery case to prevent materials from moving between the interior and exterior of the battery case, it can be formed of a material having high sealing performance. To ensure such insulation, corrosion resistance, and sealing performance, the second sealant layer can be made of 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, poly(p-phenylene benzobisoxazole), polyarylate, Teflon, and glass fiber. Preferably, the second sealant layer can be made of a polyolefin-based resin such as, for example, polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene can be composed of cast polypropylene, acid-modified polypropylene, polypropylene-ethylene copolymer, and / or polypropylene-butene-ethylene terpolymer. Here, the acid-modified polypropylene can be maleic anhydride polypropylene (MAH PP). More preferably, the second sealant layer can include cast polypropylene (CPP) having heat sealing performance and high tensile strength.

[0060] Prismatic secondary battery

[0061] Next, a prismatic secondary battery according to the present disclosure will be described.

[0062] The prismatic secondary battery according to the present disclosure has a prismatic battery case in which an electrode assembly is accommodated, and the prismatic battery case includes a prismatic film laminate. Here, the prismatic film laminate includes a base layer, a gas barrier layer, and a sealant layer laminated in this order, wherein the gas barrier layer contains stainless steel and has a thickness of 50 μm or more, and the thickness of the base layer is in the range of 10% to 30% of the thickness of the gas barrier layer.

[0063] Hereinafter, each component of the prismatic secondary battery of the present disclosure will be described in more detail with reference to Figure 2 FIG. Figure 2 is an exploded perspective view of a prismatic secondary battery 200 according to the present disclosure. As Figure 2 shown, the prismatic secondary battery 200 according to the present disclosure may include: a prismatic battery case 210, an electrode assembly 260, electrode leads 280, an insulating portion 290, and an electrolyte (not shown).

[0064] (1) Prismatic battery case

[0065] The electrode assembly 260 may be accommodated in the prismatic battery case 210. The prismatic battery case 210 can be manufactured by molding the above-described prismatic film laminate of the present disclosure. Since the detailed configuration and physical properties of the prismatic film laminate are the same as those described above, their detailed description is omitted.

[0066] The soft-pack type battery case 210 can be manufactured by punching, stretching, molding, or elongating a soft film laminate. Thus, the soft-pack type battery case 210 can include a cup portion 222 and a receiving portion 224. The receiving portion 224 is shown as a position configured to receive the electrode assembly, that is, a receiving space formed in a notch shape inside the cup portion 222 when the cup portion 222 is formed.

[0067] According to an embodiment of the present disclosure, the soft-pack type battery case 210 can include a first case 220 and a second case 230, as Figure 2 shown. The first case 220 includes a receiving portion 224 configured to receive the electrode assembly 260, and the second case 230 can cover the receiving portion 224 from above to prevent the electrode assembly 260 from falling out of the battery case 210. As Figure 2 shown, the first case 220 and the second case 230 can be manufactured such that one side of each of the first case 220 and the second case 230 can be connected to each other, but the present disclosure is not limited thereto, and the first case 220 and the second case 230 can be manufactured in various ways, for example, separated from each other and manufactured individually.

[0068] According to another embodiment of the present disclosure, when forming the cup portion in the soft film laminate, two symmetrical cup portions 222 and 232 can be pulled out in one soft film laminate, and the cup portions 222 and 232 are formed adjacent to each other. In this case, the cup portions 222 and 232 can be formed in the first case 220 and the second case 230, respectively, as Figure 2 shown. After the electrode assembly 260 is received in the receiving portion 224 provided in the cup portion 222 of the first case 220, the bridging portion 240 formed between the two cup portions 222 and 232 can be folded so that the two cup portions 222 and 232 can face each other. In this case, the cup portion 232 of the second case 230 can be configured to receive the electrode assembly 260 from above. Thus, since two cup portions 222 and 232 receive one electrode assembly 260, a thicker electrode assembly 260 can be received compared to the case where there is only one cup portion 222. In addition, since one corner of the secondary battery 200 is formed by folding the soft-pack type battery case 210, the number of corners to be sealed can be reduced when performing a sealing process later. Therefore, the processing speed of the soft-pack type secondary battery 200 can be increased, and the number of sealing processes can be reduced.

[0069] The pouch-type battery case 210 can be sealed in a state where the electrode assembly 260 is accommodated therein, such that a part (i.e., terminal portion) of the electrode lead 280, which will be described later, is exposed. Specifically, when the electrode lead 280 is connected to the electrode tab 270 of the electrode assembly 260 and the insulating portion 290 is formed on a part of the electrode lead 280, the electrode assembly 260 can be accommodated in the accommodating portion 224 provided in the cup portion 222 of the first case 220, and the second case 230 can cover the accommodating portion 224 from above. Next, the electrolyte is injected into the accommodating portion 224, and the sealing portion 250 formed at the edges of the first case 220 and the second case 230 can be sealed.

[0070] The sealing portion 250 can be used to seal the accommodating portion 224. Specifically, the sealing portion 250 can be formed along the edge of the accommodating portion 224, so that the sealing portion 250 seals the accommodating portion 224. The temperature at which the sealing portion 250 is sealed can be in the range of 180°C to 250°C, specifically in the range of 200°C to 250°C, and more specifically in the range of 210°C to 240°C. When the sealing temperature satisfies the above numerical range, the pouch-type battery case 210 can obtain sufficient sealing strength through thermal bonding.

[0071] According to the present disclosure, when the respective sealing layers of the first case 220 and the second case 230 are laminated such that the sealant layers are in contact with each other, and then sealed for 1.6 seconds under the conditions of 210°C and 1.2 MPa, the thickness of the sealant layer at the sealing portion 250 formed in the pouch-type battery case 210 can be in the range of 54% to 86% of the thickness of the sealant layer of the pouch film laminate, specifically in the range of 55% to 85%, and more specifically in the range of 60% to 85%. When the thickness of the sealant layer of the sealing portion 250 satisfies the above numerical range with respect to the thickness of the sealant layer of the pouch film laminate, there is an effect of ensuring sufficient sealing strength while maintaining insulation performance.

[0072] (2) Electrode Assembly

[0073] The electrode assembly 260 can be inserted into the pouch-type battery case 210 and sealed in the pouch-type battery case 210 after injecting the electrolyte.

[0074] The electrode assembly 260 can be formed by sequentially laminating a positive electrode, a separator, and a negative electrode. Specifically, the electrode assembly 260 can include two types of electrodes (e.g., a positive electrode and a negative electrode) and a separator interposed between the electrodes to insulate the electrodes from each other.

[0075] The positive electrode and the negative electrode may 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 containing aluminum and copper, respectively. Generally, a paste can be formed by stirring granular active materials, auxiliary conductors, binders, conductive materials, etc. in a state where a solvent is added thereto. The solvent can be removed in a subsequent process.

[0076] A paste obtained by mixing an electrode active material with a binder and / or a conductive material is coated on a positive electrode current collector and a negative electrode current collector to manufacture the positive electrode and the negative electrode. Then, the positive electrode and the negative electrode can be stacked on both sides of a separator to manufacture an electrode assembly 260 having a predetermined shape. The types of the electrode assembly 260 include a stacked type, a wound type, and a stacked and folded type electrode assembly, but the present disclosure is not limited thereto.

[0077] The electrode assembly 260 may include an electrode tab 270.

[0078] The electrode tab 270 can be connected to each of the positive electrode and the negative electrode of the electrode assembly 260 and protrude outward from the electrode assembly 260 to serve as a path for electrons to move between the inside and the outside of the electrode assembly 260. The electrode current collector included in the electrode assembly 260 may be composed of a portion coated with the electrode active material and an end portion (i.e., a non-coated portion) not coated with the electrode active material. The electrode tab 270 can 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 Figure 2 shown, the electrode tab 270 can protrude from the electrode assembly 260 in different directions, but the present disclosure is not limited thereto, and the electrode tab 270 can protrude in various directions, such as protruding side by side in the same direction from one side.

[0079] (3) Electrode lead

[0080] The electrode lead 280 can supply power 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.

[0081] The electrode lead 280 can be 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 can be connected to the electrode assembly 260, particularly to 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.

[0082] The electrode lead 280 includes: a positive electrode lead 282, one end of the positive electrode lead 282 is connected to the positive electrode tab 272 and extends in the direction in which the positive electrode tab 272 protrudes; and a negative electrode lead 284, one end of the negative electrode lead 284 is connected to the negative electrode tab 274 and extends in the direction in which the negative electrode tab 274 protrudes. The other ends of both the positive electrode lead 282 and the negative electrode lead 284 may protrude to the outside of the battery case 210. Accordingly, the electric power generated inside the electrode assembly 260 can be supplied to the outside. Further, since each of the positive electrode tab 272 and the negative electrode tab 274 protrudes in various directions, each of the positive electrode lead 282 and the negative electrode lead 284 may also extend in various directions. The positive electrode lead 282 and the negative electrode lead 284 may be made of different materials. That is, the positive electrode lead 282 may be made of the same aluminum (Al) material as the positive electrode current collector, and the negative electrode lead 284 may be made of the same copper (Cu) material as the negative electrode current collector or made of copper material coated with nickel (Ni). A part of the electrode lead 280 that protrudes to the outside of the battery case 210 may be formed as a terminal portion and electrically connected to an external terminal.

[0083] (4) Insulating portion

[0084] The insulating portion 290 can prevent the electric power generated from the electrode assembly 260 from flowing into the battery case 210 through the electrode lead 280 and maintain the seal of the battery case 210. To this end, the insulating portion 290 may be formed of a non-conductive material that does not conduct electricity well. Generally, the insulating portion 290 is easily attached to the electrode lead 280 and is generally made of a relatively thin insulating tape or film, but the present disclosure is not limited thereto, and any member capable of insulating the electrode lead 280 may be used.

[0085] The insulating portion 290 may be provided to surround the outer peripheral surface of the electrode lead 280. Specifically, at least a part of the electrode lead 280 may be surrounded by the insulating portion 290. In this case, the insulating portion 290 may be provided between the electrode lead 280 and the pouch-type battery case 210. The insulating portion 290 may be arranged such that the insulating portion 290 is restricted to the sealing portion 250 that seals the first case 220 and the second case 230 of the pouch-type battery case 210 by thermal bonding, and the electrode lead 280 may be attached to the battery case 210.

[0086] (5) Electrolyte

[0087] The pouch-type secondary battery 200 according to the present disclosure may further include an electrolyte (not shown) injected into the pouch-type battery case 210. The electrolyte is used to move lithium ions generated by the electrochemical reaction of the electrodes during charging and discharging of the secondary battery 200, 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 such a solid electrolyte may be flexible to be easily deformed by an external force. [Detailed Description of Embodiments]

[0089] Hereinafter, the present disclosure will be described in more detail through specific examples of the present disclosure. However, it should be understood that the following examples are merely illustrative to assist in understanding the present disclosure and are not intended to limit the scope of the present disclosure. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present disclosure, and such changes and modifications fall within the scope of the appended patent claims.

[0090] Examples and Comparative Examples

[0091] Example 1: Manufacture of a Pouch Film Laminate

[0092] A first adhesive film having a width of 266 mm, a length of 50 m, and a thickness of 3 μm and a polyethylene terephthalate (PET) film having a width of 266 mm, a length of 50 m, and a thickness of 6 μm are sequentially laminated on one surface of a stainless steel thin film having a width of 266 mm, a length of 50 m, and a thickness of 80 μm. A polypropylene (PP) film having a width of 266 mm, a length of 50 m, and a thickness of 80 μm is laminated on the other surface of the stainless steel thin film. Thus, a pouch film laminate having a structure in which the polypropylene film, the stainless steel thin film, the first adhesive film, and the polyethylene terephthalate film are sequentially laminated is manufactured.

[0093] Here, the polypropylene film is a sealant layer, the stainless steel thin film is a gas barrier layer, and the first adhesive film and the polyethylene terephthalate film are base layers.

[0094] Example 2: Manufacture of a Pouch Film Laminate

[0095] A pouch film laminate is manufactured in the same manner as in Example 1, except that a stainless steel thin film having a thickness of 60 μm is used.

[0096] Example 3: Manufacture of a Pouch Film Laminate

[0097] A pouch film laminate is manufactured in the same manner as in Example 1, except that a stainless steel thin film having a thickness of 50 μm is used.

[0098] Comparative Example 1: Manufacture of Soft Encapsulation Laminate

[0099] A soft encapsulation laminate was manufactured in the same manner as in Example 1, except that a first adhesive film having a width of 266 mm, a length of 50 m, and a thickness of 3 μm; a nylon film having a width of 266 mm, a length of 50 m, and a thickness of 25 μm; a second adhesive film having a width of 266 mm, a length of 50 m, and a thickness of 3 μm; and a polyethylene terephthalate (PET) film having a width of 266 mm, a length of 50 m, and a thickness of 25 μm were sequentially laminated on one surface of a stainless steel thin film having a width of 266 mm, a length of 50 m, and a thickness of 80 μm.

[0100] Here, the polypropylene film is a sealant layer, the stainless steel thin film is a gas barrier layer, and the first adhesive film, nylon film, second adhesive film, and polyethylene terephthalate film are base layers.

[0101] Comparative Example 2: Manufacture of Soft Encapsulation Laminate

[0102] A soft encapsulation laminate was manufactured in the same manner as in Example 1, except that a stainless steel thin film having a thickness of 60 μm was used, and only a first adhesive layer having a thickness of 3 μm was used as the base layer.

[0103] Comparative Example 3: Manufacture of Soft Encapsulation Laminate

[0104] A soft encapsulation laminate was manufactured in the same manner as in Example 1, except that a stainless steel thin film having a thickness of 45 μm was used.

[0105] Experimental Example 1: Evaluation of Forming Depth and Plasticity of Soft Encapsulation Laminate

[0106] The forming depth of each soft encapsulation laminate manufactured in Examples 1 to 3 and Comparative Examples 1 to 3 was measured. Specifically, after cutting the soft encapsulation laminate into a width of 266 mm and a length of 200 mm, the cut soft encapsulation laminate was processed and stretched using a soft pack molding device (Kosho High-Tech Co., Ltd.) to mold a cup portion having a width of 90 cm and a length of 160 cm until the soft encapsulation laminate ruptured, and then the forming depth (unit: mm) of the cup portion was measured. The results are shown in Table 1 below.

[0107] In addition, cup portion molding was performed a total of 10 times on the soft encapsulation laminate, and it was visually confirmed whether the soft encapsulation laminate ruptured during the molding of the cup portion. The results are shown in Table 1 below.

[0108] - Good: The soft encapsulation laminate did not rupture when measured 10 times

[0109] - Poor: At least one soft film laminate breaks when measured 10 times

[0110] Experimental Example 2: Evaluation of the insulation of the soft film laminate

[0111] Each of the soft film laminates manufactured in Examples 1 to 3 and Comparative Examples 1 to 3 was cut into a size of 90 mm × 150 mm, and then stored in a vacuum oven at 60 °C for 24 hours. After that, the dielectric breakdown voltage was measured in a drying chamber using a dielectric breakdown voltage measuring device (Hioki E.E. Corp.). Specifically, aluminum films each having a thickness of 5t were provided on the upper and lower surfaces of the soft film laminate. After that, the positive electrode of the measuring device was connected to the gas barrier layer of the soft film laminate, and the negative electrode of the measuring device was connected to the aluminum film in contact with the base layer. Then, the voltage applied when the leakage current measured while applying voltage at a rate of 100 V / s was 0.5 mA or more was measured as the dielectric breakdown voltage, and the insulation was evaluated based on the following criteria.

[0112] - Good: The dielectric breakdown voltage is 1000 V or more.

[0113] - Poor: The dielectric breakdown voltage is less than 1000 V.

[0114] [Table 1]

[0115]

[0116] As shown in Table 1, it can be seen that Examples 1 to 3, which include a stainless steel having a thickness of 50 μm or more and a base layer having a thickness of 10% to 30% of the thickness of the gas barrier layer, have a greater cup forming depth and exhibit excellent soft packaging plasticity compared to Comparative Examples 2 and 3, and have excellent insulation compared to Comparative Example 2.

[0117] On the other hand, Comparative Example 1 has a plasticity at a similar level to that of the examples, but has the disadvantages that when the thickness of the soft film laminate exceeds 200 μm, the energy density of the battery cell decreases, and the manufacturing process cost increases due to the base layer having a four-layer structure. It can be seen that Comparative Example 2 has poor plasticity compared to Examples 1 to 3, and the insulation of the soft package cannot be ensured due to the thin base layer. In addition, it can be seen that Comparative Example 3 has poor plasticity compared to Examples 1 to 3. [Description of the Drawings]

[0119] 100: Soft film laminate

[0120] 110: Base layer

[0121] 120: Gas barrier layer

[0122] 130: Sealant layer

[0123] 200: Soft-pack secondary battery

[0124] 210: Soft-pack housing

[0125] 220: First housing

[0126] 222: Cup portion

[0127] 224: Accommodating portion

[0128] 230: Second housing

[0129] 232: Cup portion

[0130] 240: Bridging portion

[0131] 250: Sealing portion

[0132] 260: Electrode assembly

[0133] 270: Electrode tab

[0134] 272: Positive electrode tab

[0135] 274: Negative electrode tab

[0136] 280: Electrode lead

[0137] 282: Positive electrode lead

[0138] 284: Negative electrode lead

[0139] 290: Insulating portion

Claims

1. A flexible package laminate, comprising a base layer, a gas barrier layer, and a sealant layer laminated in sequence, wherein: the gas barrier layer contains stainless steel and has a thickness of 50 μm or more, and the thickness of the base layer is in the range of 10% to 30% of the thickness of the gas barrier layer.

2. The soft film laminate according to claim 1, wherein, The flexible package laminate has a thickness of 200 μm or less.

3. The soft film laminate according to claim 1, wherein, The thickness of the base layer is in the range of 2.5% to 6.5% of the thickness of the flexible package laminate.

4. The soft film laminate according to claim 1, wherein The thickness of the base layer is 5 μm to 20 μm.

5. The soft film laminate according to claim 1, wherein, The base layer includes polyethylene terephthalate (PET).

6. The soft film laminate according to claim 1, wherein, The thickness of the gas barrier layer is 50 μm to 100 μm.

7. The soft film laminate according to claim 1, wherein, The melting point of the gas barrier layer is 1000 °C or more.

8. The soft film laminate according to claim 1, wherein, The stainless steel contains 10% to 20% by weight of chromium.

9. The soft film laminate according to claim 1, wherein, The stainless steel contains 5% to 20% by weight of nickel.

10. A pouch-type secondary battery, comprising a pouch-type battery case accommodating an electrode assembly, wherein: the pouch-type battery case includes a flexible package laminate, the flexible package laminate includes a base layer, a gas barrier layer, and a sealant layer laminated in sequence, the gas barrier layer contains stainless steel and has a thickness of 50 μm or more, and the thickness of the base layer is in the range of 10% to 30% of the thickness of the gas barrier layer.

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