WO2024136214A1 - Stratifié de film de poche et batterie secondaire - Google Patents

Stratifié de film de poche et batterie secondaire Download PDF

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Publication number
WO2024136214A1
WO2024136214A1 PCT/KR2023/019729 KR2023019729W WO2024136214A1 WO 2024136214 A1 WO2024136214 A1 WO 2024136214A1 KR 2023019729 W KR2023019729 W KR 2023019729W WO 2024136214 A1 WO2024136214 A1 WO 2024136214A1
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WIPO (PCT)
Prior art keywords
gas barrier
barrier layer
pouch
layer
film laminate
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PCT/KR2023/019729
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English (en)
Korean (ko)
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최지은
김상훈
강경수
유형균
이재호
이지선
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주식회사 엘지에너지솔루션
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Priority claimed from KR1020230172543A external-priority patent/KR20240100238A/ko
Publication of WO2024136214A1 publication Critical patent/WO2024136214A1/fr

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  • the present invention relates to a pouch film laminate and a secondary battery manufactured by molding the same.
  • types of secondary batteries include nickel cadmium batteries, nickel hydrogen batteries, lithium ion batteries, and lithium ion polymer batteries. These 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 E-bikes, but also for large products requiring high output such as electric vehicles and hybrid vehicles, as well as for surplus power generation. It is also applied to power storage devices that store power or renewable energy and backup power storage devices.
  • the electrode active material slurry is first applied to the positive electrode current collector and the negative electrode current collector to manufacture the positive and negative electrodes, and then laminated on both sides of the separator to form an electrode assembly of a predetermined shape. forms. Then, the electrode assembly is stored in the battery case, and the electrolyte is injected and sealed.
  • Secondary batteries are classified into pouch type and can type, etc., depending on the material of the case that accommodates the electrode assembly.
  • the pouch type houses the electrode assembly in a pouch made from a laminate of polymer and metal thin films.
  • the can type accommodates the electrode assembly in a case made of materials such as metal or plastic.
  • a pouch which is a case of a pouch-type secondary battery, is manufactured by performing press processing on a flexible pouch film laminate to form a cup portion. Once the cup portion is formed, a secondary battery can be manufactured by storing the electrode assembly in the inner receiving space of the cup portion and sealing the sealing portion.
  • a pouch film laminate is formed of a plurality of layers in which a base layer is laminated on one side of a metal gas barrier layer and a sealant layer is laminated on the other side.
  • a base layer is laminated on one side of a metal gas barrier layer
  • a sealant layer is laminated on the other side.
  • aluminum pouch with aluminum applied to the gas barrier layer it has the advantage of being able to secure mechanical strength above a certain level, while being light in weight, complementing the electrochemical properties caused by the electrode assembly and electrolyte, and securing heat dissipation.
  • aluminum pouches may melt or deform when the pressure and temperature inside the cell rise due to a fire, etc.
  • the present invention provides a pouch film laminate and a pouch-type secondary battery that can improve the formability of a high-strength pouch.
  • a pouch film laminate including a sequentially laminated base layer, a gas barrier layer, and a sealant layer may be provided.
  • the gas barrier layer may include stainless steel.
  • the fracture energy difference according to Equation 1 below may be 2000J or less.
  • Breaking energy difference (J)
  • the fracture energy of the gas barrier layer in the MD direction may be 5000 J or more, and the fracture energy of the gas barrier layer in the TD direction may be 5000 J or more.
  • the difference in tensile elongation at break according to Equation 2 below may be 10% or less.
  • the tensile elongation at break in the MD direction of the gas barrier layer may be 15% or more, and the tensile elongation at break in the TD direction of the gas barrier layer may be 15% or more.
  • the difference in tensile breaking strength according to Equation 3 below may be 150 MPa or less.
  • the tensile breaking strength of the gas barrier layer in the MD direction may be 400 MPa or more, and the tensile breaking strength of the gas barrier layer in the TD direction may be 400 MPa or more.
  • the thickness of the gas barrier layer may be 30 ⁇ m to 100 ⁇ m.
  • R t (%) (thickness of gas barrier layer/thickness of pouch film laminate) ⁇ 100
  • the thickness of the pouch film laminate may be 80 ⁇ m to 300 ⁇ m.
  • a pouch-type secondary battery including a pouch-type battery case in which an electrode assembly is housed, and the pouch-type battery case includes a pouch film laminate.
  • the pouch film laminate may include a sequentially laminated base layer, a gas barrier layer, and a sealant layer.
  • the gas barrier layer may include stainless steel.
  • the fracture energy difference according to Equation 1 above may be 2000J or less.
  • the pouch film laminate includes a base layer, a gas barrier layer, and a sealant layer.
  • the gas barrier layer may include stainless steel, and the gas barrier layer may be disposed between the base layer and the sealant layer.
  • the difference between the fracture energy of the gas barrier layer in the MD (machine direction) direction and the fracture energy of the gas barrier layer in the TD (transverse) direction may be 2000 J or less.
  • the MD direction may be parallel to the rolling direction when manufacturing the gas barrier layer, and the TD direction may be perpendicular to the rolling direction when manufacturing the gas barrier layer.
  • the fracture energy of the gas barrier layer in the MD direction may be 5000 J or more, and the fracture energy of the gas barrier layer in the TD direction may be 5000 J or more.
  • the difference between the tensile elongation at break in the MD direction of the gas barrier layer and the tensile elongation at break in the TD direction of the gas barrier layer may be 10% or less.
  • the tensile fracture extension length in the MD direction of the gas barrier layer may be 15% or more of the original length in the MD direction of the gas barrier layer, and the TD of the gas barrier layer
  • the tensile fracture elongation length in the direction may be 15% or more of the original length in the TD direction of the gas barrier layer.
  • the difference between the tensile breaking strength of the gas barrier layer in the MD direction and the tensile breaking strength of the gas barrier layer in the TD direction may be 150 MPa or less.
  • the tensile breaking strength of the gas barrier layer in the MD direction may be 400 MPa or more, and the tensile breaking strength of the gas barrier layer in the TD direction may be 400 MPa or more.
  • the thickness of the gas barrier layer may be 10% to 50% of the thickness of the pouch film laminate.
  • the thickness of the gas barrier layer may be 30 ⁇ m to 100 ⁇ m.
  • the thickness of the pouch film laminate may be 80 ⁇ m to 300 ⁇ m.
  • the pouch-type secondary battery may include a pouch-type battery case in which an electrode assembly is stored.
  • the pouch-type battery case may include a pouch film laminate.
  • the pouch film laminate may include a base layer, a gas barrier layer, and a sealant layer.
  • the gas barrier layer may include stainless steel.
  • the gas barrier layer may be disposed between the base layer and the sealant layer.
  • the difference between the fracture energy of the gas barrier layer in the MD (machine direction) direction and the fracture energy of the gas barrier layer in the TD (transverse) direction may be 2000 J or less.
  • the MD direction may be parallel to the rolling direction when manufacturing the gas barrier layer, and the Transverse Direction (TD) direction may be perpendicular to the rolling direction when manufacturing the gas barrier layer.
  • the fracture energy of the gas barrier layer in the MD direction may be 5000 J or more, and the fracture energy of the gas barrier layer in the TD direction may be 5000 J or more.
  • the difference between the tensile elongation at break in the MD direction of the gas barrier layer and the tensile elongation at break in the TD direction of the gas barrier layer may be 10% or less.
  • the tensile fracture extension length in the MD direction of the gas barrier layer may be 15% or more of the original length in the MD direction of the gas barrier layer, and the TD of the gas barrier layer
  • the tensile fracture elongation length in the direction may be 15% or more of the original length in the TD direction of the gas barrier layer.
  • the difference between the tensile breaking strength of the gas barrier layer in the MD direction and the tensile breaking strength of the gas barrier layer in the TD direction may be 150 MPa or less.
  • the tensile breaking strength of the gas barrier layer in the MD direction may be 400 MPa or more, and the tensile breaking strength of the gas barrier layer in the TD direction may be 400 MPa or more.
  • the thickness of the gas barrier layer may be 10% to 50% of the thickness of the pouch film laminate.
  • the thickness of the gas barrier layer may be 30 ⁇ m to 100 ⁇ m.
  • a method for manufacturing a pouch-type secondary battery includes providing a pouch film laminate including a base layer, a gas barrier layer, and a sealant layer, the gas barrier layer being disposed between the base layer and the sealant layer; measuring a first fracture energy of the gas barrier layer along a first direction of the gas barrier layer; measuring a second fracture energy of the gas barrier layer along a second direction that is perpendicular to the first direction of the gas barrier layer; determining a difference between the first fracture energy and the second fracture energy to be less than or equal to a preset threshold; and manufacturing a pouch-type secondary battery by molding the pouch film laminate to accommodate the electrode assembly.
  • the preset threshold may be 2000J or less.
  • the first direction is the MD direction of the gas barrier layer
  • the MD direction of the gas barrier layer may be a direction parallel to the rolling direction when manufacturing the gas barrier layer.
  • the pouch film laminate according to the present invention includes a gas barrier layer containing stainless steel, and is characterized in that the difference between the fracture energy of the gas barrier layer in the MD direction and the fracture energy in the TD direction is 2000 J or less.
  • a pouch film laminate using a gas barrier layer that satisfies the above conditions has excellent durability at high temperature and high pressure, and at the same time, the formability of the pouch film laminate is significantly improved and a sufficient forming depth can be secured.
  • 1 is a photographic image of a gas barrier layer to illustrate the MD direction and TD direction of the gas barrier layer.
  • Figure 2 is a cross-sectional view of the pouch film laminate according to the present invention.
  • Figure 3 is an exploded and assembled view of a pouch-type secondary battery according to the present invention.
  • a and/or B herein means A, or B, or A and B.
  • the MD (Machine Direction) direction is a direction parallel to the rolling direction when manufacturing a thin film for forming a gas barrier layer
  • the Transverse Direction (TD) direction is a direction perpendicular to the rolling direction when manufacturing a thin film for forming a gas barrier layer. it means.
  • the MD direction and TD direction of the gas barrier layer can be confirmed with the naked eye through patterns formed on the surface of the gas barrier layer.
  • Figure 1 shows a veining pattern extending along the MD direction and perpendicular to the TD direction.
  • breaking energy refers to the total energy required until the specimen breaks when pulled in one direction (for example, when the specimen breaks and has two or more separated parts), and stress -Can correspond to the area of the strain curve.
  • the breaking energy is calculated by cutting the specimen to 15 mm in width and 100 mm in length, then fastening both ends of the specimen in the longitudinal direction to the upper/lower jig of the UTM (at this time, the end of the part fastened to the upper jig and the part fastened to the lower jig)
  • the spacing between the ends may be 50 mm) and can be measured by performing a tensile test by pulling in a 180° direction at a speed of 5 mm/min at room temperature (25°C).
  • tensile elongation at break means the percentage (%) of the length increased until the specimen breaks compared to the initial length of the specimen when the specimen is pulled in one direction.
  • Tensile fracture elongation is determined by cutting the specimen to 15 mm in width and 100 mm in length, then fastening both ends of the specimen in the longitudinal direction to the upper/lower jig of the UTM (at this time, the ends of the part fastened to the upper jig and the ends of the part fastened to the lower jig)
  • the spacing between the ends of the part may be 50 mm) and can be measured by performing a tensile test by pulling in a 180° direction at a speed of 5 mm/min at room temperature (25°C).
  • the tensile breaking strength means the maximum load applied until the specimen breaks when the specimen is pulled in one direction divided by the cross-sectional area of the specimen before tensioning. More specifically, the tensile breaking strength is determined by preparing a specimen with a width of 15 mm and a length of 100 mm, and then fastening both ends of the specimen in the longitudinal direction to the upper/lower jig of the UTM (at this time, the ends and lower parts of the part fastened to the upper jig are The gap between the ends of the part fastened to the jig may be 50 mm) and then pulled in a 180° direction at a speed of 5 mm/min at room temperature (25°C), the maximum load applied until the specimen breaks is the specimen before tensioning. It can be defined as the value divided by the cross-sectional area of .
  • the pouch film laminate according to the present invention includes a sequentially laminated base layer, a gas barrier layer, and a sealant layer, and the gas barrier layer includes stainless steel, and the fracture energy difference according to Equation 1 below is 2000. J and below.
  • Breaking energy difference (J)
  • the present invention solves the problem of reduced formability, which was a conventional problem when using stainless steel, a high-strength material, as a gas barrier layer component, by adjusting the difference in fracture energy in the MD and TD directions of the gas barrier layer to a specific range.
  • the pouch film laminate of the present invention can have excellent durability and high moldability, and thus can accommodate a large number of electrode assemblies, improving cell energy density, and providing a pouch with excellent durability against high heat and pressure. It is possible to implement a type secondary battery.
  • FIG. 2 is a cross-sectional view of the pouch film laminate 100 according to the present invention. As shown in FIG. 2, a base layer 110, a gas barrier layer 120, and a sealant layer 130 may be sequentially laminated on the pouch film laminate 100.
  • a base layer 110 As shown in FIG. 2, a base layer 110, a gas barrier layer 120, and a sealant layer 130 may be sequentially laminated on the pouch film laminate 100.
  • a sealant layer 130 may be sequentially laminated on the pouch film laminate 100.
  • the base layer 110 is formed on the outermost layer of the pouch film laminate 100 to protect the secondary battery from friction and collision with the outside.
  • the base layer 110 is made of polymer and can electrically insulate the electrode assembly from the outside.
  • the thickness of the base layer 110 may be 5 ⁇ m to 100 ⁇ m, specifically 7 ⁇ m to 70 ⁇ m, and more specifically 25 ⁇ m to 60 ⁇ m. When the thickness of the base layer 110 satisfies the above range, external insulation is excellent, and the entire pouch is not thick, so the energy density compared to the volume of the secondary battery can be excellent.
  • the base layer 110 is made of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, and polyparaphenylene. It may be made of one or more materials selected from the group consisting of benzobisoxazole, polyarylate, Teflon, and glass fiber.
  • the base layer may be made of polyethylene terephthalate (PET), nylon, or a combination thereof, which has wear resistance and heat resistance. More preferably, the base layer is polyethylene terephthalate; Or it may include polyethylene terephthalate and nylon.
  • the base layer 110 may have a single layer structure.
  • the base layer 110 is made of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenyl. It may be made of one or more materials selected from the group consisting of lenbenzobisoxazole, polyarylate, Teflon, and glass fiber.
  • the base layer may preferably include at least one of polyester-based films such as polyethylene terephthalate and polybutylene terephthalate, which have abrasion resistance and heat resistance, specifically polyethylene terephthalate, but is not limited thereto.
  • the pouch film laminate may further include an adhesive layer interposed between the base layer 110 and a gas barrier layer 120 to be described later.
  • the adhesive layer may be introduced for adhesion or attachment of the base layer and the gas barrier layer, and adhesive layers known in the art may be used without limitation.
  • the base layer 110 may have a composite film structure formed by layering two or more materials.
  • the base layer 110 may include a first base layer, a second base layer, and/or an adhesive layer.
  • the thickness of the base layer 110 refers to the total thickness of the first base layer, the second base layer, and/or the adhesive layer.
  • the first base layer may be disposed on the outermost layer of the pouch film laminate, and the second base layer may be disposed between the first base layer and the gas barrier layer.
  • the adhesive layer may be disposed between the first substrate layer and the second substrate layer, or between the second substrate layer and the gas barrier layer.
  • the first base layer, the second base layer, and the adhesive layer may each be made of materials with different materials and/or physical properties.
  • An interface may exist between the first base layer, the second base layer, and the adhesive layer. This means that the first base layer, the second base layer, and the adhesive layer are different layers and can be formed separately.
  • the first base layer may be a layer disposed on the outermost layer of the pouch film laminate.
  • the first base layer may serve to prevent moisture from penetrating from the outside of the pouch.
  • the first base layer is polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzoate. It may be made of one or more materials selected from the group consisting of bisoxazole, polyarylate, Teflon, and glass fiber.
  • the first base layer may include at least one of polyester-based films having abrasion resistance and heat resistance, such as polyethylene terephthalate and polybutylene terephthalate, but is not limited thereto.
  • the second base layer may be a layer disposed between the first base layer and the gas barrier layer 120.
  • the second base layer may play a role in improving the formability of the pouch.
  • 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.
  • the second base layer may include nylon 6, and in this case, there is an advantage of improving the formability of the pouch due to the excellent stretching properties of nylon 6.
  • the gas barrier layer 120 is laminated between the base layer 110 and the sealant layer 130 to secure the mechanical strength of the pouch, block gas or moisture from outside the secondary battery, and prevent gas or moisture from entering the pouch-type battery case. This is to prevent electrolyte leakage.
  • the gas barrier layer 120 includes stainless steel.
  • the gas barrier layer 120 may be manufactured by molding and/or processing a stainless steel thin film.
  • the gas barrier layer 120 containing stainless steel has relatively low thermal conductivity and is effective in preventing or delaying heat diffusion to other cells in the event of thermal runaway, and has relatively high toughness to prevent cracks in the pouch during use of the pouch-type battery. Occurrence can be suppressed.
  • stainless steel when stainless steel is included in the gas barrier layer, there is a problem of lowering the formability of the pouch film laminate.
  • the present invention sets the relationship of fracture energy in the MD and TD directions of the gas barrier layer to a specific level. By adjusting it, it is possible to implement a pouch film that can improve durability at high temperature and high pressure and at the same time has improved formability.
  • the stainless steel contains metal elements other than iron (Fe), such as copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn). ) may include one or more species selected from the group consisting of
  • the SUS grade of the stainless steel may be at least one of SUS304, SUS304I, SUS304L, and SUS316L, and specifically, it may be at least one of SUS304I and SUS316L.
  • the fracture energy difference according to Equation 1 below may be 2000 J or less, specifically 2000 J or less, more specifically 1950 J or less, and even more specifically 800 J or less.
  • the lower limit of the breaking energy difference according to Equation 1 below is not particularly limited.
  • the breaking energy difference according to Equation 1 below may be 150 J or more, specifically 200 J or more.
  • the breaking energy refers to the total energy that can be absorbed until the specimen breaks when the specimen is pulled in one direction. If the difference between the fracture energy in the MD direction and the TD direction exceeds 2000 J, the difference between the fracture energy in the MD direction and the TD direction increases, causing the pouch film laminate to fracture in the direction where the fracture energy is relatively low. There is a problem with pinholes occurring.
  • Fracture energy difference (J)
  • the fracture energy of the gas barrier layer 120 in the MD direction may be 5000 J or more, specifically 8000 J or more, more specifically 10000 J or more, and even more specifically 14300 J or more.
  • the upper limit of the fracture energy in the MD direction of the gas barrier layer 120 is not particularly limited, and may be, for example, 20000 J or less.
  • the fracture energy in the TD direction of the gas barrier layer 120 may be 5000 J or more, specifically 8000 J or more, more specifically 10000 J or more, and even more specifically 13000 J or more.
  • the upper limit of the fracture energy of the gas barrier layer 120 in the TD direction is not particularly limited, and may be, for example, 20000 J or less.
  • the breaking energy in the MD or TD direction satisfies the above numerical range, even if a certain level of energy is applied to the pouch film laminate during pouch molding, the pouch film laminate is not immediately destroyed but stretches, thereby ensuring pouch moldability. there is.
  • the fracture energy in the MD direction and TD direction of the gas barrier layer can be changed by adjusting the physical properties of the stainless steel as needed included in the gas barrier layer.
  • the fracture energy in the MD and TD directions of the gas barrier layer can be realized by adjusting the rolling temperature, cooling temperature, and cooling time of the stainless steel included in the gas barrier layer.
  • the difference in tensile elongation at break according to Equation 2 below is 10% or less, specifically 0.2% to 10%, more specifically 0.4% to 9.2%, and even more specifically 0.4% to 3.0%.
  • tensile elongation at break means the percentage (%) of the length increased until the specimen breaks compared to the initial length of the specimen when the specimen is pulled in one direction. If the difference between the tensile elongation at break in the MD direction and the tensile elongation at break in the TD direction satisfies the above numerical range, the elongation difference in the MD and TD directions is reduced when forming the pouch, which has the effect of improving the formability of the pouch. .
  • the tensile elongation at break in the MD direction of the gas barrier layer 120 may be 15% or more, specifically 16% to 60%, and more specifically 17% to 55%. Additionally, the tensile elongation at break in the TD direction of the gas barrier layer 120 may be 15% or more, specifically 16% to 60%, and more specifically 17% to 55%.
  • the pouch film laminate is sufficiently stretched during pouch molding, thereby ensuring the processing depth of the cup portion.
  • the difference in tensile strength at break according to Equation 3 below may be 150 MPa or less, specifically 140 MPa or less, more specifically 120 MPa or less, and more specifically 40 MPa or less.
  • the lower limit of the difference in tensile strength at break according to Equation 3 is not particularly limited, and for example, the difference in tensile strength at break according to Equation 3 below may be 10 MPa or more, specifically 20 MPa or more.
  • the tensile breaking strength means the maximum load applied until the specimen breaks when the specimen is pulled in one direction divided by the cross-sectional area of the specimen before tensioning.
  • the tensile strength deviation in the MD and TD directions is reduced during pouch molding, which has the effect of improving the formability of the pouch. there is.
  • the tensile breaking strength of the gas barrier layer 120 in the MD direction may be 400 MPa or more, specifically 400 MPa to 1000 MPa, and more specifically 400 MPa to 900 MPa. Additionally, the tensile breaking strength of the gas barrier layer 120 in the TD direction may be 400 MPa or more, specifically 400 MPa to 1000 MPa, and more specifically 400 MPa to 900 MPa. If the tensile breaking strength in the MD or TD direction satisfies the above numerical range, the problem of the pouch film laminate being broken or pinholes occurring even if a tensile load above a certain level is applied to the pouch for pouch molding can be prevented.
  • the thickness of the gas barrier layer 120 may be 30 ⁇ m to 100 ⁇ m, specifically 40 ⁇ m to 90 ⁇ m, and more specifically 50 ⁇ m to 80 ⁇ m. When the thickness of the gas barrier layer 120 satisfies the above range, formability and gas barrier performance are excellent when molding the cup portion, and sufficient mechanical strength to withstand the internal pressure of the pouch can be secured.
  • the gas barrier layer according to the present invention includes stainless steel, there may be no or insignificant change in the thickness of the gas barrier layer due to the cup portion forming or stretching process of the pouch film laminate.
  • the percentage R t of the thickness of the gas barrier layer with respect to the thickness of the pouch film laminate calculated by Equation 4 below is 10% to 50%, specifically 25% to 40%, more specifically 30% to 50%. It could be 37%.
  • R t (%) (thickness of gas barrier layer/thickness of pouch film laminate) ⁇ 100
  • the sealant layer 130 is used to completely seal the inside of the pouch-type battery case by being thermally bonded to each other at the sealing portion when the pouch-type battery case accommodating the electrode assembly inside is sealed.
  • the sealant layer 130 may be formed of a material having excellent thermal adhesive strength.
  • 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 electrolyte inside the pouch-type battery case, it may be formed of a material having insulating properties and corrosion resistance. In addition, since the sealant layer 130 must completely seal the inside of the pouch-type battery case to block material movement between the inside and outside, it may be formed of a material with high sealing properties (for example, excellent thermal bonding strength). To ensure such insulation, corrosion resistance, and sealing properties, the sealant layer 130 may be formed of a polymer material.
  • the sealant layer 130 is made of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, and polyparaphenylene. It may be made of one or more materials selected from the group consisting of benzobisoxazole, polyarylate, Teflon, and glass fiber, and may preferably be made of polyolefin resin such as polypropylene (PP) and/or polyethylene (PE). there is.
  • PP polypropylene
  • PE polyethylene
  • polypropylene consists of cast polypropylene (CPP), acid modified polypropylene (PPa), polypropylene-ethylene copolymer, and/or polypropylene-butylene-ethylene terpolymer. It can be.
  • the thickness of the sealant layer 130 may be 30 ⁇ m to 130 ⁇ m, specifically 50 ⁇ m to 120 ⁇ m, and more specifically 70 ⁇ m to 100 ⁇ m. When the thickness of the sealant layer satisfies the above range, there is an effect of securing the moldability of the pouch film laminate while securing the sealing strength of the sealing portion.
  • the sealant layer 130 may have a single film structure made of any one material.
  • the sealant layer 130 may have a composite film structure formed by forming two or more materials as separate layers.
  • the sealant layer 130 may include a first sealant layer and a second sealant layer.
  • the first sealant layer may be a layer disposed adjacent to the gas barrier layer
  • the second sealant layer may be a layer disposed on the first sealant layer.
  • the first sealant layer and the second sealant layer may each be made of different materials and/or 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 can be formed separately.
  • the first sealant layer is made of acid-modified polypropylene (PPa) in order to ensure long-term adhesion between the gas barrier layer and the first sealant layer.
  • the acid modified polypropylene may be maleic anhydride polypropylene (MAH PP).
  • the second sealant layer may be formed of a material having insulation, corrosion resistance, and sealing properties. Specifically, since the second sealant layer is in direct contact with the electrode assembly 260 and/or the electrolyte inside the receiving space 224, it may be formed of a material having insulating properties and corrosion resistance. In addition, since the second sealant layer must completely seal the inside of the battery case and block material movement between the inside and outside, it can be formed of a material with high sealing properties. To ensure insulation, corrosion resistance, and sealing properties, the second sealant layer is made of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, and aramid.
  • the second sealant layer may be made of a polyolefin-based resin such as polypropylene (PP) and/or polyethylene (PE).
  • the polypropylene may be composed of unstretched polypropylene, acid modified polypropylene, polypropylene-ethylene copolymer, and/or polypropylene-butylene-ethylene terpolymer.
  • the acid modified polypropylene may be maleic anhydride polypropylene (MAH PP).
  • the second sealant layer may include cast polypropylene (CPP), which has heat sealability and high tensile strength.
  • the thickness of the pouch film laminate according to the present invention is 80 ⁇ m to 300 ⁇ m, specifically 80 ⁇ m to 250 ⁇ m, more specifically 100 ⁇ m to 250 ⁇ m, even more specifically 120 ⁇ m to 230 ⁇ m, and even more specifically 120 ⁇ m to 190 ⁇ m. It can be.
  • the pouch cup portion can be easily formed and sufficient mechanical strength to withstand the internal pressure of the pouch can be secured.
  • a pouch-type secondary battery includes a pouch-type battery case in which an electrode assembly is stored, the pouch-type battery case includes a pouch film laminate, and the pouch film laminate includes sequentially laminated base layers and a gas barrier. layer and a sealant layer, the gas barrier layer includes stainless steel, and the fracture energy difference according to Equation 1 below is 2000J or less.
  • Breaking energy difference (J)
  • FIG 3 is an exploded and assembled view of the pouch-type secondary battery 200 according to the present invention.
  • the pouch-type secondary battery 200 of the present invention includes a pouch-type battery case 210, an electrode assembly 260, an electrode lead 280, an insulator 290, and an electrolyte (not shown). may include.
  • the pouch-type battery case 210 can store the electrode assembly 260 inside.
  • the pouch-type battery case 210 can be manufactured by molding the pouch film laminate of the present invention described above. Since the detailed configuration and physical properties of the pouch film laminate are the same as described above, detailed description is omitted.
  • the pouch film laminate may be drawn, formed and stretched by a punch or the like to manufacture the pouch-type battery case 210.
  • the pouch-type battery case 210 may include a cup portion 222 and a receiving portion 224.
  • the receiving part 224 is a place to store the electrode assembly, and may mean a receiving space formed in the shape of a pocket inside the cup part 222 as the cup part 222 is formed.
  • the pouch-type battery case 210 may include a first case 220 and a second case 230, as shown in FIG. 3.
  • the first case 220 includes a receiving portion 224 capable of accommodating the electrode assembly 260, and the second case 230 prevents the electrode assembly 260 from falling out of the battery case 210.
  • the receiving portion 224 can be covered from above.
  • the first case 220 and the second case 230 may be manufactured with one side connected to each other as shown in FIG. 3, but are not limited to this and may be manufactured in various ways, such as being separated from each other and manufactured separately.
  • cup portions 222 and 232 in one pouch film laminate can be drawn and molded adjacent to each other.
  • cup portions 222 and 232 may be formed in the first case 220 and the second case 230, respectively, as shown in FIG. 3.
  • the two cup parts 222 and 232 are placed between the two cup parts 222 and 232 so that the two cup parts 222 and 232 face each other.
  • the bridge portion 240 formed in can be folded.
  • the cup portion 232 of the second case 230 can accommodate the electrode assembly 260 from above.
  • the two cup parts 222 and 232 accommodate one electrode assembly 260, an electrode assembly 260 with a thicker thickness can be accommodated than when there is only one cup part 222.
  • one corner of the secondary battery 200 is formed by folding the pouch-type battery case 210, the number of corners to be sealed may be reduced when a sealing process is performed later. Accordingly, the process speed of the pouch-type secondary battery 200 can be improved and the number of sealing processes can be reduced.
  • the pouch-type battery case 210 may be sealed while accommodating the electrode assembly 260 so that a portion of the electrode lead 280, that is, the terminal portion, 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 in a portion of the electrode lead 280, the cup portion of the first case 220 ( The electrode assembly 260 is accommodated in the accommodating part 224 provided in 222, and the second case 230 may cover the accommodating part 224 from the top. Next, an electrolyte is injected into the receiving portion 224 and the sealing portion 250 formed on the edge of the first case 220 and the second case 230 may be sealed.
  • the sealing portion 250 may serve to seal the receiving portion 224. Specifically, the sealing portion 250 may be formed along the edge of the receiving portion 224 and seal the receiving portion 224.
  • the temperature at which the sealing portion 250 is sealed may be 180°C to 250°C, specifically 200°C to 250°C, and more specifically 210°C to 240°C. When the sealing temperature satisfies the above numerical range, the pouch-type battery case 210 can secure sufficient sealing strength through thermal bonding.
  • the pouch-type battery case 210 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.
  • the thickness of the sealant layer of the sealing portion 250 satisfies the above numerical range compared to the thickness of the sealant layer of the pouch film laminate, there is an effect of maintaining insulation properties while securing sufficient sealing strength.
  • the electrode assembly 260 may be inserted into the pouch-type battery case 210 and sealed by the pouch-type battery case 210 after electrolyte injection.
  • the electrode assembly 260 may be formed by sequentially stacking an anode, a separator, and a cathode.
  • the electrode assembly 260 may include two types of electrodes, an anode and a cathode, and a separator interposed between the electrodes to insulate the electrodes from each other.
  • the positive electrode and the negative electrode may have a structure in which an active material slurry is applied to an electrode current collector in the form of a metal foil or metal mesh containing aluminum and copper, respectively.
  • Slurry can typically be formed by stirring granular active materials, auxiliary conductors, binders, and conductive materials with a solvent added. The solvent may be removed in subsequent processing.
  • a slurry mixed with an electrode active material, a binder, and/or a conductive material is applied to the positive electrode current collector and the negative electrode current collector to manufacture the positive electrode and the negative electrode, and the electrode assembly 260 is manufactured by stacking them on both sides of the separator. It can be manufactured in the shape of. Types of the electrode assembly 260 may include a stack type, a jelly roll type, and a stack and fold type, but are not limited thereto.
  • the electrode assembly 260 may include an electrode tab 270.
  • the electrode tab 270 is connected to the anode and cathode of the electrode assembly 260, respectively, and protrudes outward from the electrode assembly 260 to become a path for electrons to move between the inside and outside of the electrode assembly 260. You can.
  • the electrode current collector included in the electrode assembly 260 may be composed of a portion to which the electrode active material is applied and a distal portion to which the electrode active material is not applied, that is, an uncoated portion.
  • the electrode tab 270 may be formed by cutting the uncoated area or by connecting a separate conductive member to the uncoated area using ultrasonic welding or the like. As shown in FIG. 3, the electrode tabs 270 may protrude in different directions from the electrode assembly 260, but are not limited to this and may protrude in various directions, such as protruding side by side in the same direction from one side. there is.
  • the electrode lead 280 may supply electricity to the outside of the secondary battery 200.
  • the electrode lead 280 may be connected to the electrode tab 270 of the electrode assembly 260 by spot welding, etc.
  • the electrode lead 280 is connected to the electrode assembly 260 and may protrude out of the pouch-type battery case 210 via the sealing portion 250. Specifically, one end of the electrode lead 280 is connected to the electrode assembly 260, especially the electrode tab 270, and the other end of the electrode lead 280 may protrude to the outside of the pouch-type battery case 210. .
  • the electrode lead 280 has one end connected to the positive tab 272 and extends in the direction in which the positive tab 272 protrudes, and one end connected to the negative electrode tab 274 and the negative electrode tab 274. It may include a negative electrode lead 284 extending in this protruding direction. The other ends of both the positive lead 282 and the negative lead 284 may protrude to the outside of the battery case 210 . Therefore, electricity generated inside the electrode assembly 260 can be supplied to the outside. In addition, since the positive electrode tab 272 and the negative electrode tab 274 each protrude in various directions, the positive electrode lead 282 and the negative electrode lead 284 may also extend in various directions.
  • the anode lead 282 and the cathode lead 284 may be made of different materials.
  • the positive electrode lead 282 may be made of the same aluminum (Al) material as the positive electrode current collector, and the negative lead 284 may be made of the same copper (Cu) material as the negative electrode current collector or a copper material coated with nickel (Ni).
  • a portion of the electrode lead 280 protruding to the outside of the battery case 210 may become a terminal portion and be electrically connected to an external terminal.
  • the insulating portion 290 prevents electricity generated from the electrode assembly 260 from flowing into the battery case 210 through the electrode lead 280 and maintains the sealing of the battery case 210.
  • the insulating portion 290 may be formed of a non-conductive material that does not conduct electricity well.
  • the insulating portion 290 is easily attached to the electrode lead 280 and an insulating tape or film with a relatively thin thickness is often used, but the insulating portion 290 is not limited to this, and any member capable of insulating the electrode lead 280 may be used. You can.
  • the insulating portion 290 may be arranged to surround the outer peripheral surface of the electrode lead 280. Specifically, at least a portion of the electrode lead 280 may be surrounded by the insulating portion 290. In this case, the insulating portion 290 may be disposed between the electrode lead 280 and the pouch-type battery case 210. The insulating portion 290 may be located limited to the sealing portion 250 where the first case 220 and the second case 230 of the pouch-type battery case 210 are heat-sealed, and the electrode lead 280 may be provided. It can be attached to the battery case 210.
  • the pouch-type secondary battery 200 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 electrode during charging/discharging of the secondary battery 200, and is made of a non-aqueous organic electrolyte solution that is a mixture of lithium salt and organic solvents or a polymer using a polymer electrolyte. It can be included.
  • the electrolyte may include a sulfide-based, oxide-based, or polymer-based solid electrolyte, and such solid electrolyte may have the flexibility to be easily deformed by external force.
  • peeling may occur at the interface of the sealed battery case 210 with relatively weak adhesive force.
  • delamination may occur along the interface between sealant layers that are heat bonded to each other.
  • thermal bonding between sealant layers with improved flow characteristics when melted is smoothly achieved, so that the adhesive force on the interface is maintained high and can have excellent sealing strength.
  • a first adhesive film with a thickness of 3 ⁇ m, a nylon film with a thickness of 25 ⁇ m, a second adhesive film with a thickness of 3 ⁇ m, and a polyethylene terephthalate (PET) film with a thickness of 12 ⁇ m were sequentially laminated on one side of the stainless steel thin film with a thickness of 60 ⁇ m.
  • a polypropylene (PP) film with a thickness of 80 ⁇ m was laminated on the other side of the stainless steel thin film.
  • the SUS grade of the stainless steel included in the stainless steel thin film was SUS304I.
  • the polypropylene film is a sealant layer
  • the stainless steel thin film is a gas barrier layer
  • the first adhesive film, nylon film, second adhesive film, and polyethylene terephthalate film are base layers.
  • a pouch film laminate was manufactured in the same manner as Example 1, except that stainless steel thin films with different tensile and fracture properties were used.
  • the SUS grade of the stainless steel included in the stainless steel thin film of Example 2 was SUS304I.
  • a pouch film laminate was manufactured in the same manner as Example 1, except that stainless steel thin films with different tensile and fracture properties were used.
  • the SUS grade of the stainless steel included in the stainless steel thin film of Example 3 was SUS304I.
  • a pouch film laminate was manufactured in the same manner as Example 1, except that stainless steel thin films with different tensile and fracture properties were used.
  • the SUS grade of the stainless steel included in the stainless steel thin film of Example 4 was SUS304I.
  • a pouch film laminate was manufactured in the same manner as Example 1, except that stainless steel thin films with different tensile and fracture properties were used.
  • the SUS grade of the stainless steel included in the stainless steel thin film of Example 5 was SUS316L.
  • a pouch film laminate was manufactured in the same manner as Example 1, except that stainless steel thin films with different tensile and fracture properties were used.
  • the SUS grade of the stainless steel included in the stainless steel thin film of Comparative Example 1 was SUS304I.
  • a pouch film laminate was manufactured in the same manner as Example 1, except that stainless steel thin films with different tensile and fracture properties were used.
  • the SUS grade of the stainless steel included in the stainless steel thin film of Comparative Example 2 was SUS304I.
  • a pouch film laminate was manufactured in the same manner as Example 1, except that stainless steel thin films with different tensile and fracture properties were used.
  • the SUS grade of the stainless steel included in the stainless steel thin film of Comparative Example 3 was SUS304I.
  • the tensile breaking strength, tensile breaking elongation, and breaking energy of the stainless steel thin film were measured by cutting the stainless steel thin film to 15 mm in width and 100 mm in length to produce a specimen, and then attaching both ends in the longitudinal direction of the specimen to the upper/lower part of the UTM. Fasten to the jig (at this time, the distance between the end of the part fastened to the upper jig and the end of the part fastened to the lower jig is 50 mm) and then pull in the direction of 180° at a speed of 5 mm/min at room temperature (25°C). Tests were conducted and each measurement was performed. The measurement results are shown in Table 1 below.
  • the maximum forming depth of the pouch film laminates prepared in Examples 1 to 5 and Comparative Examples 1 to 3, respectively, was measured. Specifically, when the pouch film laminate is cut to 266 mm in width and 200 mm in height, and then cold formed to form a cup portion of 90 mm in width and 160 mm in height, the processing depth just before the pouch film laminate is fractured is the maximum processing depth (unit). :mm). Ten pouch film laminates of Examples 1 to 5 and Comparative Examples 1 to 3 were prepared and the maximum processing depth measurement experiment was performed 10 times, and the average values are shown in Table 1 below.
  • Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 MD direction
  • Tensile breaking strength (MPa) 622.5 507.3 788.2 652.6 580.0 532.1 576.7 670.3
  • Tensile breaking elongation (%) 35.2 43.9 21.2 34.4 40.9 30.4 26.8 31.2
  • Breaking energy (J) 17987 14358 15870 18834 19074 13233 12897 14241 TD direction
  • Tensile breaking elongation (%) 35.8 52.3 17.1 48.6 39.0 38.6 44.9 20.1
  • Breaking energy (J) 17346 13425 13957 17623 17501 17501 24332 12103 ⁇
  • Tensile breaking strength difference (MPa) 36.6 117.0 44.7 129.3 30.7 17.2 65.7 142.0 Difference

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  • Sealing Battery Cases Or Jackets (AREA)

Abstract

Un stratifié de film de poche selon la présente invention comprend une couche de base, une couche de barrière aux gaz et une couche d'étanchéité, la couche de barrière aux gaz comprenant de l'acier inoxydable, la couche de barrière aux gaz étant disposée entre la couche de base et la couche d'étanchéité, et la différence entre l'énergie de rupture de la couche de barrière aux gaz dans la direction de la machine (MD) et l'énergie de rupture de la couche de barrière aux gaz dans la direction transversale (TD) étant inférieure ou égale à 2 000 J.
PCT/KR2023/019729 2022-12-22 2023-12-01 Stratifié de film de poche et batterie secondaire WO2024136214A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR10-2022-0182363 2022-12-22
KR20220182363 2022-12-22
KR10-2023-0172543 2023-12-01
KR1020230172543A KR20240100238A (ko) 2022-12-22 2023-12-01 파우치 필름 적층체 및 이차 전지

Publications (1)

Publication Number Publication Date
WO2024136214A1 true WO2024136214A1 (fr) 2024-06-27

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Application Number Title Priority Date Filing Date
PCT/KR2023/019729 WO2024136214A1 (fr) 2022-12-22 2023-12-01 Stratifié de film de poche et batterie secondaire

Country Status (1)

Country Link
WO (1) WO2024136214A1 (fr)

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