Soft film laminate and secondary battery

Abstract

A soft envelope laminate according to the present disclosure includes a base material layer, a gas barrier layer, and a sealant layer that are laminated in this order, in which the base material layer includes a first base material layer, a first adhesive layer, and a second base material layer that are laminated in this order, and the first adhesive layer includes metal oxide particles in an amount of greater than 15 wt% to less than 60 wt% based on a total weight of the first adhesive layer.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority from Korean Patent Application No. 10-2023-0015851, filed on February 6, 2023, and Korean Patent Application No. 10-2024-0009052, filed on January 19, 2024, the disclosures of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a soft-pack film laminate and a soft-pack secondary battery prepared by molding the soft-pack film laminate. Background Art

[0004] Secondary batteries are used in a variety of fields, including small products such as digital cameras, P-DVDs, MP3 players, mobile phones, PDAs, portable gaming devices, power tools, and electric bicycles, as well as large products requiring high output, such as electric and hybrid vehicles, energy storage devices, and backup energy storage devices for storing surplus generated electricity or renewable energy. Types of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries.

[0005] A secondary battery can be prepared by housing an electrode assembly in which a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrodes are alternately stacked in a battery case, injecting an electrolyte, and then sealing the battery case. Depending on the material of the case housing the electrode assembly, secondary batteries are classified into soft-pack secondary batteries, can-type secondary batteries, etc.

[0006] After forming a cup portion by pressing the flexible soft-pack film laminate, the electrode assembly can be housed in the accommodation space inside the cup portion and the sealing portion is sealed to prepare a soft-pack secondary battery. The soft-pack film laminate is composed of a plurality of layers in which a polymer film such as polyethylene terephthalate is laminated on one surface of the metal gas barrier layer and a sealant layer of a thermoplastic polyolefin-based resin is laminated on the other surface. When sealing the soft-pack battery case, the sealant layers can be thermally bonded to each other to form the sealing portion.

[0007] Recently, as the capacity of soft-pack secondary batteries has increased, the demand for soft packs with excellent formability has increased. In the case where the gas barrier layer is formed to be thicker to prepare a soft pack with good formability, there is a problem that the sealant layer is not easily melted when the soft-pack battery case is sealed. Generally, in order to solve this problem, a method of increasing the sealing temperature and / or sealing time is used as a method of applying more heat during the sealing of the soft-pack battery case. However, when the sealing temperature is increased to 220°C or more, there is a problem of deformation due to the melting of the base material layer, and when the sealing time is increased, there is a problem of reduced productivity due to an increase in the tact time. Summary of the Invention

[0008] Technical issues

[0009] One aspect of the present disclosure provides a soft-pack film laminate that can ensure sealing quality and workability by reducing the sealing time while preventing deformation of the sealing portion in the process of sealing a soft-pack film laminate, as well as a soft-pack battery case and a soft-pack secondary battery prepared by molding the soft-pack film laminate.

[0010] Technical Solution

[0011] According to an embodiment of the present disclosure, a soft coating laminate is provided, comprising: a base material layer, a gas barrier layer and a sealant layer stacked in sequence, wherein the base material layer comprises a first base material layer, a first adhesive layer and a second base material layer stacked in sequence, and the first adhesive layer comprises metal oxide particles in an amount greater than 15 wt % to less than 60 wt % based on the total weight of the first adhesive layer.

[0012] The metal oxide particles may include at least one selected from the group consisting of CaO, MnO, SrO, MgO, and ZnO. The average particle size D of the metal oxide particles is 50 It can be 0.2 μm to 1 μm.

[0013] The first adhesive layer may include the metal oxide particles in an amount of about 16 wt % to about 59 wt % based on the total weight of the first adhesive layer.

[0014] The first base material layer may have a thickness of 10 μm to 50 μm. The first base material layer may include a polyester base film.

[0015] The first adhesive layer may have a thickness of 1 μm to 10 μm. The first adhesive layer may include at least one selected from the group consisting of a polyurethane-based polymer, an epoxy-based polymer, and an acrylic-based polymer.

[0016] The second base material layer may have a thickness of 10 μm to 50 μm. The second base material layer may include a polyamide-based film.

[0017] The base material layer may further include a second adhesive layer provided between the second base material layer and the gas barrier layer.

[0018] The thickness of the gas barrier layer may be 30 μm to 100 μm.

[0019] The thickness of the sealant layer may be 30 μm to 130 μm.

[0020] According to another embodiment of the present disclosure, a soft-pack type battery case is provided, which is prepared by molding the soft-pack film laminate.

[0021] According to another embodiment of the present disclosure, a soft-pack secondary battery is provided, including: a soft-pack battery case prepared by molding the soft-pack film laminate; and an electrode assembly accommodated in the soft-pack battery case.

[0022] Beneficial effects

[0023] With respect to conventional soft-pack film laminates, although the first base material layer prevents moisture from penetrating from the outside of the soft pack, due to thickness and material limitations, moisture outside the soft pack may also reach the second base material layer by passing through the first base material layer. In this case, moisture may be easily absorbed into the second base material layer by forming hydrogen bonds with functional groups (e.g., amide structures) in the polymer included in the second base material layer. Therefore, with respect to a soft-pack type battery case prepared by molding a conventional soft-pack film laminate, if it is sealed at a high temperature to supply sufficient heat within a prescribed tact time, the moisture absorbed in the second base material layer in the soft-pack film laminate evaporates to generate bubbles in the second base material layer, and therefore there is a problem of degradation of the insulation performance of the soft pack due to deformation and damage of the sealing portion.

[0024] Sealing a soft-pack battery case made of a conventional soft-pack film laminate at low temperatures to address this issue increases sealing time, thereby reducing production process efficiency. Furthermore, reducing the moisture content per unit weight of the soft-pack film laminate to less than 1000 ppm to address this issue can make storage management of the soft-pack film laminate difficult or expensive after production.

[0025] In order to solve the above problems, in the present disclosure, since the first adhesive layer provided between the first base material layer and the second base material layer includes metal oxide particles in an amount of greater than 15wt% to less than 60wt%, the moisture introduced from the outside of the soft pack can be removed by hydroxylation of the metal oxide in the first adhesive layer before being absorbed into the second base material layer. Therefore, since the generation of bubbles due to evaporation of moisture in the second base material layer can be suppressed even when the soft pack type battery case prepared by the soft pack film laminate of the present disclosure is sealed at a temperature of 220°C or above, the sealing time can be shortened while preventing deformation of the sealing portion. Therefore, the sealing quality and workability of the soft pack type battery case prepared by the soft pack film laminate of the present disclosure can be ensured, and the durability and life characteristics of the soft pack type secondary battery can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The following drawings attached to the specification illustrate preferred examples of the present disclosure by way of example and are used to enable the technical concept of the present disclosure to be further understood together with the detailed description of the present disclosure given below, and thus the present disclosure should not be interpreted solely by the contents in these drawings.

[0027] Figure 1 is a cross-sectional view of a soft-coat laminate according to the present disclosure.

[0028] Figure 2 1 is an exploded assembly diagram of a soft-pack secondary battery according to the present disclosure. DETAILED DESCRIPTION

[0029] The advantages and features of the present disclosure and their implementation methods will be explained by the following embodiments described with reference to the accompanying drawings. However, the present disclosure can be implemented in different forms and should not be construed as being limited to the embodiments described herein. However, these embodiments are provided so that the present disclosure will become thorough and complete, and will fully convey the scope of the present disclosure to those of ordinary skill in the art. In addition, the present disclosure is limited only by the scope of the claims. Throughout the specification, the same reference numerals represent the same elements.

[0030] Unless otherwise defined, all terms used herein (including technical and scientific terms) may be intended to have the meanings understood by those of ordinary skill in the art. In addition, unless otherwise specifically defined, the terms defined in commonly used dictionaries should not be interpreted abnormally or exaggeratedly.

[0031] The terms used herein are for the purpose of describing specific example embodiments only and are not intended to limit the present disclosure. In this specification, unless otherwise specified, terms in the singular may include plural forms. It will also be understood that when used in this specification, the terms "include" and / or "comprising" specify the presence of the components described, but do not exclude the presence or addition of one or more other components.

[0032] In this specification, unless specifically described to the contrary, when it is mentioned that a part includes specific components, this means that other components may also be included, and does not exclude other components.

[0033] The description "A and / or B" in this specification means A, or B, or A and B.

[0034] In this specification, "%" means wt% unless otherwise specifically stated.

[0035] In this manual, D 50 Indicates the particle size at which the cumulative volume is 50% in the particle size distribution curve. For example, D can be measured by using a laser diffraction method. 50 Laser diffraction can typically measure particle sizes from submicrometers to several millimeters, and can obtain highly reproducible and high-resolution results.

[0036] Soft film laminate

[0037] The soft envelope laminate according to the present disclosure includes a base material layer, a gas barrier layer and a sealant layer stacked in sequence, wherein the base material layer includes a first base material layer, a first adhesive layer and a second base material layer stacked in sequence, and the first adhesive layer includes metal oxide particles in an amount greater than 15 wt % to less than 60 wt % based on the total weight of the first adhesive layer.

[0038] Figure 1 is a cross-sectional view of a soft-coated laminate 100 according to the present disclosure. Figure 1 Each configuration of the soft cover laminate 100 of the present disclosure is described in more detail.

[0039] (1) Base material layer

[0040] The base material layer 110 is formed as the outermost layer of the soft package laminate 100 to protect the secondary battery from friction and collision with the outside. The base material layer 110 is formed of a polymer so that it can electrically insulate the electrode assembly from the outside.

[0041] The thickness of the base material layer 110 may be 5 μm to 100 μm, particularly 7 μm to 70 μm, and more particularly 25 μm to 60 μm. When the thickness of the base material layer 110 satisfies the above range, the energy density to volume ratio of the secondary battery may be excellent because the external insulation is excellent and the entire soft pack is not thick.

[0042] The base material layer 110 according to the present disclosure has a composite layer structure formed by laminating two or more materials. An adhesive layer can be provided between the layers in the composite layer structure. Specifically, the base material layer 110 according to the present disclosure includes: a first base material layer 112, a first adhesive layer 116, and a second base material layer 114. In addition, the base material layer 110 may also include a second adhesive layer 118 provided between the second base material layer 114 and the gas barrier layer 120.

[0043] The first base material layer 112 may be a layer provided as the outermost layer of the soft envelope laminate, and the second base material layer 114 may be a layer provided between the first base material layer 112 and the gas barrier layer 120. The first adhesive layer 116 may be a layer provided between the first base material layer 112 and the second base material layer 114. The second adhesive layer 118 may be a layer provided between the second base material layer 114 and the gas barrier layer 120. The first base material layer 112, the second base material layer 114, the first adhesive layer 116, and the second adhesive layer 118 may be formed of materials having different materials and / or physical properties, respectively. An interface may exist between the various layers of the base material layer 110 including the first base material layer 112, the second base material layer 114, the first adhesive layer 116, and the second adhesive layer 118. This means that the various layers are different layers from each other and can be formed separately.

[0044] Hereinafter, each of the above-described first base material layer 112 , second base material layer 114 , first adhesive layer 116 , and second adhesive layer 118 will be described in more detail.

[0045] (1) First base material layer

[0046] The first base material layer 112 may be the outermost layer of the soft pack film laminate as described above. In this case, the first base material layer 112 may prevent moisture from penetrating from the outside of the soft pack.

[0047] The first base material layer 112 may be formed of at least one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber. Preferably, the first base material layer 112 may include a polyester base film having wear resistance and heat resistance. For example, the first base material layer 112 may include at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, but is not limited thereto.

[0048] The thickness of the first base material layer 112 can be 10 μm to 50 μm, particularly 10 μm to 40 μm, and more particularly 12 μm to 25 μm. When the thickness of the first base material layer 112 falls within the aforementioned range, moisture penetration into the interior of the soft-pack film stack can be effectively suppressed, while ensuring the insulation and formability of the soft-pack. Furthermore, since the entire soft-pack is not thick, the secondary battery has an excellent energy density to volume ratio.

[0049] 2) Second base material layer

[0050] The second base material layer 114 may be a layer provided between the first base material layer 112 and the gas barrier layer 120. In this case, the second base material layer 114 may play a role in improving the moldability of the soft package.

[0051] The second base material layer 114 may include a polyamide-based film. For example, the second base material layer 114 may include at least one selected from the group consisting of nylon 6, nylon (6,6), nylon MXD6 (polyxylylene adipamide), nylon 4, nylon (4,6), and nylon (4,10), but is not limited thereto. Preferably, the second base material layer 114 may include nylon 6. In this case, due to the excellent elongation properties of nylon 6, the moldability of the soft bag can be improved.

[0052] The thickness of the second base material layer 114 may be 10 μm to 50 μm, particularly 10 μm to 40 μm, and more particularly 15 μm to 35 μm. When the thickness of the second base material layer 114 falls within the above numerical range, a decrease in the energy density to volume ratio of the secondary battery due to an excessive increase in the thickness of the soft pack film laminate can be prevented while ensuring the formability of the soft pack.

[0053] The second base material layer 114 may include an additive. By including the additive in the second base material layer 114, the physical properties of the second base material layer 114 may be changed. For example, as an additive to adjust the tensile strength of the second base material layer 114, at least one of carbon fiber, glass fiber, and aramid fiber may be added.

[0054] 3) First adhesive layer

[0055] The first adhesive layer 116 may be a layer provided between the first base material layer 112 and the second base material layer 114. In this case, the first adhesive layer 116 may serve to adhere the first base material layer 112 and the second base material layer 114 to each other.

[0056] The first adhesive layer 116 may include at least one selected from the group consisting of a polyurethane-based polymer, an epoxy-based polymer, and an acrylic-based polymer, but is not limited thereto. Preferably, the first adhesive layer 116 may include a polyurethane-based polymer, and in this case, the first adhesive layer 116 may be easily formed and cut while being bonded to the first base material layer 112 and the second base material layer 114.

[0057] The thickness of the first adhesive layer 116 may be 1 μm to 10 μm, particularly 2 μm to 8 μm, and more particularly 2 μm to 5 μm. When the thickness of the first adhesive layer 116 falls within the above numerical range, sufficient adhesion between the first base material layer 112 and the second base material layer 114 is ensured while preventing a decrease in the energy density to volume ratio of the secondary battery due to an excessive increase in the thickness of the soft envelope laminate.

[0058] The first adhesive layer 116 includes metal oxide particles 140. Before moisture passing through the first base material layer 112 is introduced into the second base material layer 114, the metal oxide particles 140 may be hydroxylated by reacting with the moisture to remove the moisture.

[0059] The metal oxide particles 140 may include at least one selected from the group consisting of CaO, MnO, SrO, MgO, and ZnO. Preferably, the metal oxide particles 140 may include at least one of CaO and MgO that are favorable for hydroxylation with water.

[0060] The metal oxide particles 140 may be included in an amount of greater than 15 wt% to less than 60 wt% based on the total weight of the first adhesive layer 116. Specifically, the metal oxide particles 140 may be included in an amount of greater than 15 wt%, 16 wt% or 20 wt% or more, and less than 60 wt%, 59 wt% or less, or 50 wt% or less, based on the total weight of the first adhesive layer 116. For example, the metal oxide particles 140 may be included in an amount of greater than 15 wt% to less than 60 wt%, preferably 16 wt% to 59 wt%, and more preferably 20 wt% to 50 wt%, based on the total weight of the first adhesive layer 116. When the metal oxide particles 140 are included in an amount of 15 wt% or less in the first adhesive layer 116, since the moisture introduced into the second base material layer 114 is not sufficiently removed, when the soft pack type battery case prepared from the soft pack film laminate is sealed at a temperature of 220° C. or more, bubbles are generated in the second base material layer due to the evaporation of the moisture contained in the second base material layer, thereby causing a problem of deterioration of the insulation performance of the soft pack due to deformation and damage of the sealing portion. In the case where the first adhesive layer 116 includes metal oxide particles 140 in an amount of 60 wt % or more, the adhesion between the first base material layer 112 and the second base material layer 114 is reduced due to the excessive increase in the amount of metal oxide particles 140 in the first adhesive layer 116. As a result, there is a problem of delamination between the first base material layer 112 and the second base material layer 114 or the inability to perform stacking correctly.

[0061] The average particle size D of the metal oxide particles 140 50 The average particle size D of the metal oxide particles 140 may be 0.2 μm to 1 μm, specifically 0.2 μm to 0.8 μm, and more specifically 0.3 μm to 0.7 μm. 50 When the above numerical range is met, the preparation of the metal oxide particles 140 can be easy, the coating performance of the composition for molding the first adhesive layer 116 including the metal oxide particles 140 can be ensured, and damage to the first base material layer 112 and the second base material layer 114 that are in direct contact with the first adhesive layer 116 can be prevented.

[0062] 4) Second adhesive layer

[0063] The second adhesive layer 118 may be a layer provided between the second base material layer 114 and the gas barrier layer 120. In this case, the second adhesive layer 118 may serve to bond the second base material layer 114 and the gas barrier layer 120 to each other.

[0064] The second adhesive layer 118 may include at least one selected from the group consisting of a polyurethane-based polymer, an epoxy-based polymer, and an acrylic-based polymer, but is not limited thereto. Preferably, the second adhesive layer 118 may include a polyurethane-based polymer. In this case, the second adhesive layer 118 can be easily formed and cut while being bonded to the second base material layer 114 and the gas barrier layer 120.

[0065] The thickness of the second adhesive layer 118 may be 1 μm to 10 μm, particularly 2 μm to 8 μm, and more particularly 2 μm to 5 μm. When the thickness of the second adhesive layer 118 falls within the above numerical range, sufficient adhesion between the second base material layer 114 and the gas barrier layer 120 is ensured while preventing a decrease in the energy density to volume ratio of the secondary battery due to an excessive increase in the thickness of the soft envelope laminate.

[0066] (2) Gas barrier layer

[0067] The gas barrier layer 120 is laminated between the base material layer 110 and the sealant layer 130 to ensure mechanical strength of the pouch, block entry and exit of gas or moisture from outside the secondary battery, and prevent leakage of electrolyte from inside the pouch-type battery case.

[0068] The gas barrier layer 120 may be formed of a metal. For example, the gas barrier layer may be a metal thin film including at least one metal selected from the group consisting of aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti), and invar (INVAR), but is not limited thereto.

[0069] According to an embodiment of the present disclosure, the gas barrier layer 120 can be formed of an aluminum alloy film. When the gas barrier layer 120 is formed using an aluminum alloy film, the gas barrier layer 120 is lightweight while ensuring mechanical strength higher than a predetermined level, electrochemical performance can be compensated by the electrode assembly and the electrolyte, and heat dissipation performance can be ensured. The aluminum alloy film may contain elements other than aluminum (Al). For example, the aluminum alloy film may contain at least one selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0070] In another example, the gas barrier layer 120 may be formed of a stainless steel film. Specifically, the gas barrier layer 120 may be prepared by molding and / or processing a stainless steel film. Since the gas barrier layer 120 formed of stainless steel has a relatively low thermal conductivity, it effectively prevents or delays the diffusion of heat to other battery cells during thermal runaway, and since it has a relatively high toughness, it can inhibit the generation of cracks in the soft pack during the use of the soft pack type battery. Stainless steel may contain elements other than iron (Fe), for example, at least one selected from the group consisting of copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si) and zinc (Zn).

[0071] The thickness of the gas barrier layer 120 may be 30 to 100 μm, specifically 30 to 90 μm, and more specifically 40 to 80 μm. When the thickness of the gas barrier layer 120 satisfies the above range, gas barrier properties and moldability are excellent when the cup portion is molded.

[0072] (3) Sealant layer

[0073] When sealing the pouch-type battery case containing the electrode assembly, the sealant layer 130 is used to completely seal the interior of the pouch-type battery case by thermally bonding each other at the sealing portion. To this end, the sealant layer 130 may be formed of a material having excellent thermal bonding strength.

[0074] The sealant layer 130 can 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-pack battery case, the sealant layer 130 can be formed of a material having insulation and corrosion resistance. In addition, since the sealant layer 130 completely seals the interior of the soft-pack battery case to prevent the material from moving between the inside / outside, the sealant layer 130 can be formed of a material having high sealing properties (e.g., excellent thermal bonding strength). In order to ensure such insulation, corrosion resistance and sealing properties, the sealant layer 130 can be formed of a polymer material.

[0075] The sealant layer 130 may be formed of at least one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, poly(terephthalaldehyde benzobisoxazole), polyarylate, Teflon, and glass fiber, and may preferably be formed of a polyolefin-based resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene (PP) may be composed of cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene terpolymer.

[0076] The thickness of the sealant layer 130 may be 30 to 130 μm, particularly 50 to 120 μm, and more particularly 70 to 100 μm. When the thickness of the sealant layer satisfies the above range, the formability of the soft film laminate and the sealing strength of the sealing portion are ensured.

[0077] The sealant layer 130 according to the present disclosure may have a single-layer structure formed of any one material. Alternatively, the sealant layer 130 may have a composite layer structure formed by laminating two or more materials separately. Specifically, the sealant layer 130 may include a first sealant layer and a second sealant layer. In this case, the first sealant layer may be a layer arranged adjacent to the gas barrier layer, and the second sealant layer may be a layer arranged on the first sealant layer. The first sealant layer and the second sealant layer may be formed of materials having different materials and / or physical properties, respectively. There may 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 from each other and may be formed separately.

[0078] In order to ensure long-term adhesion between the gas barrier layer and the first sealant layer, it is particularly desirable that the first sealant layer is formed of acid-modified polypropylene (PPa). Herein, the acid-modified polypropylene may be maleic anhydride polypropylene (MAH PP).

[0079] The second sealant layer can be formed of a material having insulation, corrosion resistance and sealing properties. Figure 2 224) inside the electrode assembly ( Figure 2260) and / or electrolyte are in direct contact, so the second sealant layer 134 can be formed of a material with insulation and corrosion resistance. In addition, since the second sealant layer completely seals the interior of the battery housing to prevent material from moving between the inside / outside, the second sealant layer 134 can be formed of a material with high sealing. In order to ensure such insulation, corrosion resistance and sealing, the second sealant layer can be formed by at least one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyterephthalaldehyde benzobisoxazole, polyarylate, Teflon and glass fiber. Preferably, the second sealant layer can be formed of a polyolefin-based resin such as polypropylene (PP) and / or polyethylene (PE). In this case, polypropylene can be composed of cast polypropylene, acid-modified polypropylene, polypropylene ethylene copolymer and / or polypropylene-butene-ethylene terpolymer. Herein, the acid-modified polypropylene may be maleic anhydride polypropylene (MAH PP). More preferably, the second sealant layer may include cast polypropylene (CPP) having high tensile strength and heat sealability.

[0080] Soft-pack secondary batteries

[0081] Next, a pouch-type secondary battery according to the present disclosure will be described.

[0082] The soft-pack secondary battery according to the present disclosure includes a soft-pack battery case prepared by molding the above-mentioned soft-pack film laminate and an electrode assembly housed in the soft-pack battery case. Specifically, the soft-pack secondary battery according to the present disclosure includes a soft-pack battery case housing an electrode assembly, the soft-pack battery case is prepared by molding the soft-pack film laminate, and the soft-pack film laminate includes a base material layer, a gas barrier layer, and a sealant layer stacked in sequence, wherein the base material layer includes a first base material layer, a first adhesive layer, and a second base material layer stacked in sequence, and the first adhesive layer includes metal oxide particles in an amount greater than 15wt% to less than 60wt% based on the total weight of the first adhesive layer.

[0083] In the following, reference will be made to Figure 2 Each configuration of the pouch-type secondary battery of the present disclosure is described in more detail.

[0084] Figure 2 FIG is an exploded assembly diagram of a soft-pack type secondary battery 200 according to the present disclosure. Figure 2 As shown, the pouch-type secondary battery 200 of the present disclosure may include a pouch-type battery case 210 , an electrode assembly 260 , an electrode lead 280 , an insulating portion 290 , and an electrolyte (not shown).

[0085] (1) Soft-pack battery case

[0086] The soft-pack type battery case 210 can be prepared by molding the soft-pack film laminate of the present disclosure. The inside of the soft-pack type battery case 210 can accommodate the electrode assembly 260. Since the detailed configuration and physical properties of the soft-pack film laminate are the same as above, detailed description is omitted.

[0087] The soft-pack film laminate can be pulled out and stretched by a punch or the like to prepare a soft-pack type battery case 210. Therefore, the soft-pack type battery case 210 may include a cup portion 222 and a receiving portion 224. The receiving portion 224 is a location for receiving the electrode assembly, wherein the receiving portion 224 may refer to a receiving space formed in the shape of a pocket inside the cup portion 222 as the cup portion 222 is formed.

[0088] According to an embodiment of the present disclosure, the soft pack type battery case 210 may include a first case 220 and a second case 230. Figure 2 As shown. The first shell 220 includes a receiving portion 224 capable of receiving the electrode assembly 260, and the second shell 230 can cover the receiving portion 224 from the top so that the electrode assembly 260 will not be separated from the outside of the battery shell 210. Figure 2 As shown, the first shell 220 and the second shell 230 can be prepared by connecting one side thereof to each other, but the present disclosure is not limited thereto, and the first shell 220 and the second shell 230 can be prepared in various ways, for example, the first shell 220 and the second shell 230 are separated from each other and manufactured separately.

[0089] According to another embodiment of the present disclosure, in the case where a cup portion is formed on a soft film laminate, two symmetrical cup portions 222 and 232 can be drawn out adjacent to each other on one soft film laminate. Figure 2 As shown, cup portions 222 and 223 can be formed in the first shell 220 and the second shell 230, respectively. After the electrode assembly 260 is accommodated in the accommodating portion 224 provided in the cup portion 222 of the first shell 220, the bridge portion 240 formed between the two cup portions 222 and 232 can be folded so that the two cup portions 222 and 232 face each other. In this case, the cup portion 232 of the second shell 230 can accommodate the electrode assembly 260 from above. Therefore, since the two cup portions 222 and 232 accommodate one electrode assembly 260, an electrode assembly 260 with a greater thickness than that of a single cup portion 222 can be accommodated. In addition, since one edge of the secondary battery 200 is formed by folding the soft-pack battery case 210, the number of edges to be sealed can be reduced when the sealing process is performed later. Therefore, the process speed of the soft-pack secondary battery 200 can be increased and the number of sealing processes can be reduced.

[0090] The soft pack type battery case 210 can be sealed in a state where it accommodates 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 at a portion of the electrode lead 280, the electrode assembly 260 is accommodated in the accommodation portion 224 provided in the cup portion 222 of the first case 220, and the second case 230 can cover the accommodation portion 224 from the top. Subsequently, the electrolyte is injected into the accommodation portion 224, and the sealing portion 250 formed at the edge of the first case 220 and the second case 230 can be sealed.

[0091] The sealing portion 250 may be used to seal the accommodating portion 224. Specifically, the sealing portion 250 may be formed along the edge of the accommodating portion 224 and seal the accommodating portion 224. The temperature at which the sealing portion 250 is sealed may be in the range of 180°C to 250°C, particularly 200°C to 250°C, and more particularly 210°C to 240°C. When the sealing temperature satisfies the above numerical range, the soft pack type battery case 210 may ensure sufficient sealing strength through thermal bonding.

[0092] (2) Electrode assembly

[0093] The electrode assembly 260 may be inserted into the pouch type battery case 210 and may be sealed by the pouch type battery case 210 after injecting an electrolyte.

[0094] The electrode assembly 260 may be formed by sequentially stacking a positive electrode, a separator, and a negative electrode. Specifically, the electrode assembly 260 may include two types of electrodes, such as a positive electrode and a negative electrode, and a separator disposed between the electrodes to insulate the electrodes from each other.

[0095] The positive and negative electrodes may be structures in which active material slurries are applied to electrode current collectors in the form of metal foil or metal mesh, including aluminum and copper, respectively. Typically, the slurry is formed by stirring particulate active material, auxiliary conductor, binder, and conductive agent in the presence of a solvent. The solvent may be removed in a subsequent process.

[0096] A slurry in which an electrode active material, a binder, and / or a conductive agent are mixed is applied to a positive electrode collector and a negative electrode collector to prepare a positive electrode and a negative electrode, and the positive electrode and the negative electrode can be stacked on both sides of a separator to prepare an electrode assembly 260 in a predetermined shape. Types of the electrode assembly 260 may include, but are not limited to, a stacked type, a wound type, and a stacked folded type.

[0097] The electrode assembly 260 may include an electrode tab 270 .

[0098] The electrode terminal tab 270 is connected to each of the positive electrode and the negative electrode of the electrode assembly 260 and protrudes from the electrode assembly 260 to the outside, so that it can be a path through which electrons can 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 an electrode active material and an end portion (i.e., a non-coating portion) that is not coated with the electrode active material. The electrode terminal tab 270 may be formed by cutting the non-coating portion, or may be formed by connecting a separate conductive member to the non-coating portion by ultrasonic welding or the like. As Figure 2 As shown, the electrode tabs 270 may protrude in different directions of the electrode assembly 260, respectively, but are not limited thereto, and may be formed to protrude in various directions, for example, the electrode tabs 270 protrude side by side from one side of the electrode assembly 260 in the same direction.

[0099] (3) Electrode leads

[0100] The electrode lead 280 may supply power 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 or the like.

[0101] The electrode lead 280 is connected to the electrode assembly 260 and may protrude to the outside of the soft-pack type battery case 210 via the sealing portion 250. Specifically, one end of the electrode lead 280 is connected to the electrode assembly 260, particularly the electrode tab 270, and the other end of the electrode lead 280 may protrude to the outside of the soft-pack type battery case 210.

[0102] Electrode lead 280 may include a positive electrode lead 282, one end of which is connected to positive electrode tab 272 and extends in the direction in which positive electrode tab 272 protrudes; and a negative electrode lead 284, one end of which is connected to negative electrode tab 271 and extends in the direction in which negative electrode tab 271 protrudes. The other ends of both positive electrode lead 282 and negative electrode lead 284 may protrude outside of battery case 210. Thus, electricity generated within electrode assembly 260 can be supplied to the outside. Furthermore, since positive electrode tab 272 and negative electrode tab 271 are formed to protrude in various directions, positive electrode lead 282 and negative electrode lead 284 may also extend in various directions. The materials of positive electrode lead 282 and negative electrode lead 284 may be different from each other. That is, the positive electrode lead 282 can be formed of the same aluminum (Al) material as the positive electrode current collector, and the negative electrode lead 284 can be formed of the same copper (Cu) material or nickel (Ni) coated copper material as the negative electrode current collector. Since a portion of the electrode lead 280 protruding to the outside of the battery case 210 becomes a terminal portion, it can be electrically connected to an external terminal.

[0103] (4) Insulation

[0104] The insulating portion 290 prevents the electricity generated from the electrode assembly 260 from flowing to the battery case 210 through the electrode lead 280 and can maintain the sealing of the battery case 210. To this end, the insulating portion 290 can be formed of an insulator having non-conductivity that does not conduct electricity well. Generally, as the insulating portion 290, an insulating tape or film that is easily attached to the electrode lead 280 and is relatively thin is widely used, but the present disclosure is not limited thereto, and any member that can insulate the electrode lead 280 can be used.

[0105] The insulating portion 290 may be provided 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 provided between the electrode lead 280 and the soft-pack type battery case 210. The insulating portion 290 may be limitedly located at the sealing portion 250, and the first shell 220 and the second shell 230 of the soft-pack type battery case 210 are heat-welded to the sealing portion 250, and the electrode lead 280 may be bonded to the battery case 210.

[0106] (5) Electrolyte

[0107] The soft-pack secondary battery 200 according to the present disclosure may further include an electrolyte (not shown) injected into the soft-pack battery case 210. The electrolyte is used to move lithium ions generated by the electrochemical reaction of the electrodes during the charge and discharge of the secondary battery 200, wherein the electrolyte may include a non-aqueous organic electrolyte that is a mixture of a lithium salt and an organic solvent or a polymer electrolyte. In addition, the electrolyte may include a sulfide-based, oxide-based, or polymer-based solid electrolyte, and the solid electrolyte may have flexibility that is easily deformed by external forces.

[0108] Hereinafter, the present disclosure will be described in detail based on specific examples. However, the following examples are only used to illustrate the present disclosure, and the scope of the present disclosure is not limited thereto. It is obvious to those skilled in the art that various modifications and variations can be made within the scope and technical spirit of the present disclosure. Such modifications and variations fall within the scope of the claims included herein.

[0109] Examples and Comparative Examples

[0110] Example 1: Preparation of soft film laminate

[0111] A film having a size of 266 mm in width, 50 m in length, and 3 μm in thickness and including CaO particles (average particle size D 50 : 0.5 μm) of the first adhesive layer.

[0112] A second adhesive layer (polyurethane base film) having a width of 266 mm, a length of 50 m, and a thickness of 3 μm; a nylon film (second base material layer) having a width of 266 mm, a length of 50 m, and a thickness of 25 μm; a first adhesive layer; and a polyethylene terephthalate (PET) film (first base material layer) having a width of 266 mm, a length of 50 m, and a thickness of 12 μm are sequentially stacked on one surface of an aluminum alloy film having a width of 266 mm, a length of 50 m, and a thickness of 60 μm. A polypropylene (PP) film having a width of 266 mm, a length of 50 m, and a thickness of 80 μm is coextruded on the other surface of the aluminum alloy film. Thus, a soft envelope laminate having a structure in which polypropylene film / aluminum alloy film / second adhesive layer / nylon film / first adhesive layer / polyethylene terephthalate film are sequentially stacked is prepared.

[0113] Herein, the polypropylene film is the sealant layer, the aluminum alloy thin film is the gas barrier layer, and the second adhesive layer, the nylon film, the first adhesive layer, and the polyethylene terephthalate film are base material layers.

[0114] Example 2: Preparation of soft film laminate

[0115] A soft coat laminate was prepared in the same manner as in Example 1, except that the first adhesive layer included CaO particles in an amount of 30 wt % based on the total weight of the first adhesive layer.

[0116] Example 3: Preparation of soft film laminate

[0117] A soft coat laminate was prepared in the same manner as in Example 1, except that the first adhesive layer included CaO particles in an amount of 40 wt % based on the total weight of the first adhesive layer.

[0118] Example 4: Preparation of soft film laminate

[0119] A soft coat laminate was prepared in the same manner as in Example 1, except that the first adhesive layer included CaO particles in an amount of 50 wt % based on the total weight of the first adhesive layer.

[0120] Comparative Example 1: Preparation of soft film laminate

[0121] A soft coat laminate was prepared in the same manner as in Example 1, except that CaO particles were not included in the first adhesive layer.

[0122] Comparative Example 2: Preparation of soft film laminate

[0123] A soft coat laminate was prepared in the same manner as in Example 1, except that the first adhesive layer included CaO particles in an amount of 5 wt % based on the total weight of the first adhesive layer.

[0124] Comparative Example 3: Preparation of soft film laminate

[0125] A soft coat laminate was prepared in the same manner as in Example 1, except that the first adhesive layer included CaO particles in an amount of 10 wt % based on the total weight of the first adhesive layer.

[0126] Comparative Example 4: Preparation of soft film laminate

[0127] A soft coat laminate was prepared in the same manner as in Example 1, except that the first adhesive layer included CaO particles in an amount of 15 wt % based on the total weight of the first adhesive layer.

[0128] Comparative Example 5: Preparation of soft film laminate

[0129] A soft coat laminate was prepared in the same manner as in Example 1, except that the first adhesive layer included CaO particles in an amount of 60 wt % based on the total weight of the first adhesive layer.

[0130] Comparative Example 6: Preparation of soft film laminate

[0131] A film having a size of 266 mm in width, 50 m in length, and 3 μm in thickness and including CaO particles (average particle size D 50 : 0.5 μm) of the second adhesive layer.

[0132] A second adhesive layer; a nylon film (second base material layer) having a width of 266 mm, a length of 50 m, and a thickness of 25 μm; a first adhesive layer (polyurethane base film) having a width of 266 mm, a length of 50 m, and a thickness of 3 μm; and a polyethylene terephthalate (PET) film (first base material layer) having a width of 266 mm, a length of 50 m, and a thickness of 12 μm were sequentially stacked on one surface of an aluminum alloy film having a width of 266 mm, a length of 50 m, and a thickness of 60 μm. A polypropylene (PP) film having a width of 266 mm, a length of 50 m, and a thickness of 80 μm was coextruded on the other surface of the aluminum alloy film. Thus, a soft film laminate having a structure in which polypropylene film / aluminum alloy film / second adhesive layer / nylon film / first adhesive layer / polyethylene terephthalate film were sequentially stacked was prepared.

[0133] Herein, the polypropylene film is the sealant layer, the aluminum alloy thin film is the gas barrier layer, and the second adhesive layer, the nylon film, the first adhesive layer, and the polyethylene terephthalate film are base material layers.

[0134] Comparative Example 7: Preparation of soft film laminate

[0135] A film having a size of 266 mm in width, 50 m in length, and 3 μm in thickness and including CaO particles (average particle size D 50 : 0.5 μm) of the third adhesive layer.

[0136] A second adhesive layer (polyurethane base 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 first adhesive layer (polyurethane base 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 12 μm are sequentially stacked on one surface of an aluminum alloy film having a width of 266 mm, a length of 50 m, and a thickness of 60 μm. A third adhesive layer is stacked on the other surface of the aluminum alloy film, and a polypropylene (PP) film having a width of 266 mm, a length of 50 m, and a thickness of 80 μm is coextruded. Thus, a soft film laminate having a structure in which polypropylene film / third adhesive layer / aluminum alloy film / second adhesive layer / nylon film / first adhesive layer / polyethylene terephthalate film are sequentially stacked is prepared.

[0137] Herein, the polypropylene film is the sealant layer, the aluminum alloy thin film is the gas barrier layer, and the second adhesive layer, the nylon film, the first adhesive layer, and the polyethylene terephthalate film are base material layers.

[0138] Experimental Example 1: Measuring the moisture content per unit weight of the soft film laminate and evaluating the degree of adhesion between the first base material layer and the second base material layer

[0139] After the soft coat film laminates prepared in Examples 1 to 4 and Comparative Examples 1 to 7 were stored at 60°C and 90% relative humidity for 2 hours, the moisture content per unit weight of the soft coat film laminates was measured. Specifically, after the soft coat film laminates cut into a size of 50 mm x 40 mm were stored at 60°C and 90% relative humidity for 2 hours, the weight of moisture contained in the soft coat film laminate per unit weight of the soft coat film laminate (μg / g = ppm) was measured at 150°C using a Karl Fischer hygrometer. The measurement results are shown in Table 1 below.

[0140] Furthermore, the degree of adhesion between the first and second base material layers was evaluated by visually inspecting whether delamination occurred between the first and second base material layers in the soft envelope film laminate stored at 60°C and 90% relative humidity for 2 hours. The results are shown in Table 1 below.

[0141] O: Delamination occurs between the first base material layer and the second base material layer

[0142] X: No delamination occurs between the first base material layer and the second base material layer

[0143] Experimental Example 2: Evaluation of Deformation of the Seal in a Pouch-Type Battery Case

[0144] Two of the various soft-coat film laminates prepared in Examples 1 to 4 and Comparative Examples 1 to 7, respectively, were prepared. Thereafter, after each soft-coat film laminate was cut into a size of 266 mm in width and 200 mm in length and then folded in half into a size of 133 mm × 200 mm so that the sealant layers were in contact with each other, a soft-pack type battery case was prepared by sealing the end portions of the long sides (200 mm) under the following three conditions, respectively.

[0145] - Seal for 1.8 seconds at a sealing strip area of 200 mm x 8 mm, 210°C and a cylinder pressure of 0.1 MPa.

[0146] - Seal for 1.8 seconds at a sealing strip area of 200 mm x 8 mm, 230°C and a cylinder pressure of 0.075 MPa.

[0147] Next, for each of the pouch-type battery cases sealed at different temperatures, visual inspection was performed to determine whether the seal portion was deformed due to bubbles generated in the second base material layer located in the seal portion. The results are shown in Table 1 below.

[0148] O: The seal is deformed due to the generation of bubbles

[0149] X: No bubbles are generated and the sealing part is not deformed

[0150] [Table 1]

[0151]

[0152]

[0153] According to Table 1, regarding Examples 1 to 4 in which the first adhesive layer included metal oxide particles in an amount of greater than 15 wt % to less than 60 wt %, since bubbles were not generated in the second base material layer even when sealing was performed at a temperature of 230° C., it was confirmed that the sealing portion of the soft pack type battery case was not deformed and the lamination between the first base material layer and the second base material layer was excellent.

[0154] In contrast, regarding Comparative Examples 1 to 4 in which the first adhesive layer included metal oxide particles in an amount of 15 wt % or less, since a relatively large amount of moisture was present in the second base material layer, bubbles were generated in the second base material layer when sealing was performed at a temperature of 230° C., and thus it was confirmed that the sealing portion of the soft-pack type battery case was deformed.

[0155] In addition, regarding Comparative Example 5 in which the first adhesive layer includes metal oxide particles in an amount of 60 wt % or more, since the adhesion between the first base material layer and the second base material layer in the soft coating laminate is reduced, it can be confirmed that delamination occurs between the first base material layer and the second base material layer and lamination cannot be completed well.

[0156] In addition, with respect to Comparative Examples 6 and 7, in Comparative Examples 6 and 7, the metal oxide particles are included in an amount of greater than 15 wt % to less than 60 wt % in the second adhesive layer stacked between the second base material layer and the gas barrier layer or in the third adhesive layer stacked between the gas barrier layer and the sealant layer, rather than in the first adhesive layer stacked between the first base material layer and the second base material layer. Since there is a relatively large amount of moisture in the second base material layer, bubbles are generated in the second base material layer when sealing is performed at a temperature of 230°C, and therefore it can be confirmed that the sealing portion of the soft-pack type battery case is deformed.

[0157] (Explanation of Reference Numerals)

[0158] 100: Soft film laminate

[0159] 110: Base material layer

[0160] 112: First base material layer

[0161] 114: Second base material layer

[0162] 116: First adhesive layer

[0163] 118: Second adhesive layer

[0164] 120: Gas barrier layer

[0165] 130: Sealant layer

[0166] 140: Metal oxide particles

[0167] 200: Soft pack secondary battery

[0168] 210: Soft-pack housing

[0169] 220: First shell

[0170] 222: Cup Department

[0171] 224: Accommodation

[0172] 230: Second shell

[0173] 232: Cup Department

[0174] 240: Bridge

[0175] 250: Sealing part

[0176] 260: Electrode assembly

[0177] 270: Electrode terminal

[0178] 271: Negative terminal lug

[0179] 272: Positive terminal lug

[0180] 280: Electrode lead

[0181] 282: Positive lead

[0182] 284: Negative lead

[0183] 290: Insulation

Claims

1. A soft film laminate comprising: The base material layer, gas barrier layer and sealant layer are stacked in sequence, Wherein, the base material layer comprises a first base material layer, a first adhesive layer and a second base material layer stacked in sequence, and The first adhesive layer includes metal oxide particles in an amount of greater than 15 wt % to less than 60 wt % based on the total weight of the first adhesive layer.

2. The soft-coated laminate according to claim 1, wherein The metal oxide particles include at least one selected from the group consisting of CaO, MnO, SrO, MgO, and ZnO.

3. The soft-coated laminate according to claim 1, wherein The average particle size D of the metal oxide particles 50 0.2μm to 1μm.

4. The soft-coated laminate according to claim 1, wherein The first adhesive layer includes the metal oxide particles in an amount of about 16 wt % to about 59 wt % based on the total weight of the first adhesive layer.

5. The soft-coated laminate according to claim 1, wherein The thickness of the first base material layer is 10 μm to 50 μm. The soft-coated laminate according to claim 1 , wherein: The first base material layer includes a polyester base film.

7. The soft-coated laminate according to claim 1, wherein The first adhesive layer has a thickness of 1 μm to 10 μm.

8. The soft-coated laminate according to claim 1, wherein The first adhesive layer includes at least one selected from the group consisting of a polyurethane-based polymer, an epoxy-based polymer, and an acrylic-based polymer.

9. The soft-coated laminate according to claim 1, wherein The thickness of the second base material layer is 10 μm to 50 μm.

10. The soft-coated laminate according to claim 1, wherein The second base material layer includes a polyamide-based film.

11. The soft-coated laminate according to claim 1, wherein The base material layer further includes a second adhesive layer disposed between the second base material layer and the gas barrier layer.

12. The soft-coated laminate according to claim 1, wherein The gas barrier layer has a thickness of 30 μm to 100 μm.

13. The soft-coated laminate according to claim 1, wherein The sealant layer has a thickness of 30 μm to 130 μm. 14 . A soft-pack battery case, produced by molding the soft-pack film laminate according to claim 1 .

15. A soft-pack secondary battery comprising: A soft-pack type battery case prepared by molding the soft-pack film laminate according to any one of claims 1 to 13; as well as An electrode assembly is housed in the pouch-type battery case.

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