Pouch-type battery case and pouch-type secondary battery including the same

Abstract

The pouch-type battery case according to the present invention may include: a cup-shaped portion having a receiving space therein for accommodating electrode assemblies; a platform portion formed along the periphery of the receiving portion; and one or more gas venting portions, wherein each gas venting portion includes: a through-hole formed in at least one of the cup-shaped portion and the platform portion; a breathable membrane disposed on the inner side of the battery case to cover the through-hole; and a polymer-based protective film disposed on the outer side of the battery case to cover the through-hole. As described above, the gas venting portions are configured to continuously vent gas while exhibiting excellent performance in preventing moisture from penetrating from the outside, thereby improving the safety and lifespan of the pouch-type secondary battery.

Description

Technical Field

[0001] Cross-references to related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0045610, filed on April 3, 2024, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a pouch-type battery case and a pouch-type secondary battery including the pouch-type battery case, and more specifically, to a pouch-type battery case including a gas venting portion exhibiting excellent moisture-proof performance and a pouch-type secondary battery including the pouch-type battery case. Background Technology

[0004] Rechargeable batteries are used in a wide range of products, including small products such as digital cameras, P-DVD players, MP3 players, mobile phones, PDAs, portable gaming devices, power tools, and electric bicycles, as well as large products requiring high power, such as electric vehicles and hybrid vehicles. They are also used in power storage devices for storing surplus or renewable energy, and in backup power storage devices. Rechargeable batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries.

[0005] Secondary batteries are manufactured by housing an electrode assembly in which positive, negative, and spacers sandwiched between electrodes are alternately stacked in a battery case, injecting electrolyte, and then sealing the battery case. Depending on the material of the case housing the electrode assembly, secondary batteries are classified into pouch-type and can-type secondary batteries. Specifically, pouch-type batteries are manufactured by pressing a stretchable pouch film laminate to form a cup-shaped portion, then housing the electrode assembly within the containment space of the cup-shaped portion and sealing the portion.

[0006] When operated at high temperatures, overcharged, or short-circuited, pouch-type secondary batteries may generate gas inside the pouch. As the gas pressure inside the pouch increases, the pouch may release gas, potentially leading to an explosion or fire. To overcome these limitations, a component designed to continuously release gas without stopping battery operation is needed.

[0007] Although extensive research is underway to incorporate valve-type gas venting components for discharging gases generated inside batteries, most valve-type gas venting components are made of heavy materials and require high operating pressures, thus often failing to address the expansion caused by gas generation.

[0008] Therefore, efforts are underway to develop gas emission components that allow only gas to pass through by modifying the lead film in the electrode lead section or by punching a hole in a part of the battery box and sealing the hole with a breathable membrane, while preventing the migration of moisture and electrolyte.

[0009] However, in the case of membranes that only allow gas to pass through, as described above, depending on the materials used, there is a greater concern about the possibility of liquid infiltration and poor adhesion to the battery box when the permeability is high, and the desired level of gas emission performance cannot be achieved when the risk of liquid infiltration is reduced to zero.

[0010] Furthermore, the dimensional characteristics of the components constituting the gas emission component lead to variations in gas emission performance or liquid barrier performance. Since the specific dimensions that may affect gas emission performance have not yet been clearly identified, further research is needed to develop gas emission components that exhibit superior performance. Summary of the Invention

[0011] Technical issues

[0012] The present invention was designed to overcome the above-mentioned limitations, and therefore, one aspect of the present invention provides a pouch-type battery box that exhibits excellent moisture-proof and gas emission performance through the following design: including through-holes connecting the inside and outside of the box and a breathable membrane covering the through-holes from the inside, and further including a polymer-based protective film covering the through-holes from the outside of the battery box.

[0013] Furthermore, the present invention is designed to overcome the above-mentioned limitations, and therefore, another aspect of the present invention provides a pouch-type secondary battery exhibiting excellent safety and extended lifespan by applying the above-described pouch-type battery case.

[0014] Technical solution

[0015] [1] According to one aspect of the present invention, a pouch-type battery case is provided, the pouch-type battery case comprising: a cup-shaped portion having a receiving space for accommodating an electrode assembly; a platform portion formed along the periphery of the receiving portion; and at least one gas emission portion, wherein each gas emission portion comprises a through hole formed in at least one of the cup-shaped portion or the platform portion, a breathable membrane covering the through hole from the inside of the battery case, and a polymer-based protective film covering the through hole from the outside of the battery case.

[0016] [2] The present invention provides a pouch-type battery box according to [1] above, wherein the polymer-based protective film may include at least one selected from polypropylene, polyethylene, polytetrafluoroethylene, fluorinated ethylene propylene copolymer, perfluoroalkoxy substituted polytetrafluoroethylene and ethylene tetrafluoroethylene copolymer.

[0017] [3] The present invention provides a pouch-type battery case according to [1] and / or [2] above, wherein a polymer-based protective film may be provided around a through hole for a box adhesive portion in contact with the battery case, and a portion of the polymer-based protective film may be inserted into the battery case at the box adhesive portion.

[0018] [4] The present invention provides a pouch-type battery box according to [1] and / or [2] above, wherein the polymer-based protective film may be provided with a film bonding portion that contacts a breathable film in the through hole.

[0019] [5] The present invention provides a pouch-type battery box according to [4] above, wherein the area of ​​the polymer-based protective film is greater than or equal to the area of ​​the through hole, and the area of ​​the sealed portion is less than or equal to the area of ​​the through hole.

[0020] [6] The present invention provides a pouch-type battery case according to at least one of [1] to [5] above, wherein the polymer-based protective film may include a waterproof coating on a surface exposed to the outside of the battery case.

[0021] [7] The present invention provides a pouch-type battery case according to at least one of [1] to [6] above, wherein the polymer-based protective film may include ceramic filler.

[0022] [8] The present invention provides a pouch-type battery box according to [7] above, wherein the ceramic filler may include at least one selected from CaCO3, Ca(OH)2, CaCl2, CaO, KOH, NaOH and Na2CO3.

[0023] [9] The present invention provides a pouch-type battery case according to at least one of [1] to [8] above, wherein the breathable membrane may include an adhesive resin layer surrounding a through hole and in contact with the battery case, and a permeable resin layer disposed on the adhesive resin layer.

[0024]

[10] The present invention provides a pouch-type battery box according to [9] above, wherein the adhesive resin layer may comprise a non-fluorinated polyolefin-based resin.

[0025]

[11] The present invention provides a pouch-type battery case according to [9] and / or

[10] above, wherein the adhesive resin layer may comprise a non-fluorinated polyolefin-based resin.

[0026]

[12] The present invention provides a pouch-type battery case according to at least one of [1] to

[11] above, wherein a gas venting portion may be formed at at least one location selected from a platform portion and a cup-shaped portion located adjacent to the platform portion and having no internal contact with the electrode assembly.

[0027]

[13] The present invention provides a pouch-type battery case according to at least one of [1] to

[12] above, wherein the gas venting portion can be configured such that the adhesive resin layer contacts the pouch-type battery case.

[0028]

[14] According to another aspect of the invention, a pouch-type secondary battery is provided, the pouch-type secondary battery comprising: an electrode assembly; the aforementioned pouch-type battery case; an electrode lead connected to the electrode assembly and protruding to the outside of the pouch-type battery case via a platform portion; and a lead film disposed on the platform portion between the electrode lead and the pouch-type battery case, wherein a portion of the platform portion is sealed along the periphery of the cup-shaped portion to form a sealing portion.

[0029]

[15] According to another aspect of the invention, a battery case comprising a plurality of pouch-type secondary batteries according to claim 14 is provided, as well as a package for accommodating the pouch-type secondary batteries.

[0030] Beneficial effects

[0031] The pouch-type battery box according to the invention can be implemented as a pouch-type battery box with a gas emission section, the pouch-type battery box being designed to include a through hole connecting the inside and outside of the battery box, a breathable membrane covering the through hole from the inside of the battery box, and a polymer-based protective film covering the through hole from the outside of the battery box, thereby keeping the gas emission at at least at an appropriate level and exhibiting excellent moisture-proof performance.

[0032] Furthermore, the pouch-type secondary battery according to the present invention exhibits excellent safety and enhanced durability by applying the pouch-type battery case described above, thereby contributing to improved lifespan. Attached Figure Description

[0033] The accompanying drawings, which illustrate preferred embodiments of the invention by way of example, are used together with the following detailed description of the invention to enable a further understanding of the inventive concept, and therefore the invention should not be interpreted solely by the contents of such drawings.

[0034] Figure 1 This is an exploded view of a pouch-type secondary battery;

[0035] Figure 2 This is a plan view of a pouch-type secondary battery according to an embodiment of the present invention;

[0036] Figure 3 This is a cross-sectional view of the portion of a pouch-type secondary battery according to an embodiment of the present invention that has a gas emission section.

[0037] Figure 4 This is an enlarged cross-sectional view of the portion of a pouch-type secondary battery according to an embodiment of the present invention that has a gas emission section.

[0038] Figure 5 This is an enlarged cross-sectional view of the portion of a pouch-type secondary battery according to an embodiment of the present invention, which includes a gas emission section; and

[0039] Figure 6 This is an enlarged cross-sectional view of the portion of a pouch-type secondary battery according to an embodiment of the present invention that has a gas emission section. Detailed Implementation

[0040] The advantages and features of this disclosure, as well as methods for achieving these advantages and features, can be more readily understood from the following detailed description with reference to the embodiments and accompanying drawings. However, this disclosure may be implemented in different forms, and these embodiments are provided only to make the disclosure thorough and complete and to fully convey the scope of the disclosure to those skilled in the art, and therefore the disclosure is limited only by the scope of the appended claims. Throughout the specification, the same reference numerals denote the same elements.

[0041] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Unless explicitly and specifically defined, terms as defined in commonly used dictionaries shall not be interpreted ideally or excessively.

[0042] The terminology used herein is not intended to limit the invention, but rather to describe embodiments. As used herein, singular terms are intended to include plural forms as well, unless the context clearly indicates otherwise. The meaning of “comprising” and / or “including” as used herein does not exclude the presence or addition of one or more other components besides those mentioned.

[0043] As used herein, when an element “includes” a component, it may indicate that the element does not exclude another component, but may also include another component, unless there is an explicit description to the contrary.

[0044] As used in this article, the description “A and / or B” means either A or B or A and B.

[0045] As used herein, unless otherwise indicated, “%” indicates wt%.

[0046] The pouch-type battery box, pouch-type secondary battery, and battery case described herein may include at least one of the technical components described later, and may include any combination of technically feasible components from the following technical components.

[0047] pouch battery box

[0048] The pouch-type battery case according to the present invention includes a cup-shaped portion having a receiving space for accommodating electrode assemblies, a platform portion formed along the periphery of the receiving portion, and at least one gas venting portion, wherein each gas venting portion includes a through hole formed in at least one of the cup-shaped portion or the platform portion, a breathable membrane covering the through hole from the inside of the battery case, and a polymer-based protective film covering the through hole from the outside of the battery case.

[0049] Generally, the gas emission performance of a gas emission section is determined by the properties of the materials that constitute the gas emission section. The properties of the materials determine the water permeability and electrolyte leakage resistance, and the gas permeability also varies depending on the material. Therefore, the materials constituting the gas emission section are the decisive factors.

[0050] However, when through-holes are formed in the box, although the liquid permeability of the breathable membrane covering the through-holes is controlled, there are limitations in preventing moisture from seeping in from the outside, and when the through-holes are filled with another material to prevent moisture from seeping in, the gas emission performance may be significantly reduced.

[0051] Therefore, a design will be applied in which a polymer-based protective film is used to cover the perforations from the outside of the pouch-type battery box to prevent moisture penetration without affecting gas permeability. This design is independent of the size or material design of the breathable membrane applied to the gas emission section.

[0052] Figure 1 This is an exploded view of the pouch-type secondary battery 100 according to the present invention. Figure 2 This is a plan view of a pouch-type secondary battery 100. Figure 3 This is a cross-sectional view of the portion of the pouch-type secondary battery housing where a gas emission section is located. Figures 4 to 6 This is an enlarged cross-sectional view showing the portion of the pouch-type secondary battery housing where a gas venting section is provided. Figure 2 For ease of understanding, some components of the pouch-type secondary battery 100 are omitted. For example... Figures 1 to 6 As shown, the pouch-type secondary battery 100 of the present invention includes a pouch-type battery case 110 containing a gas emission section 200, an electrode assembly 160, an electrode lead 180, and a lead film 190 according to the present invention.

[0053] In the following text, refer to Figures 1 to 6 The present invention will be described in detail in the form of a pouch-type battery box 110 and a pouch-type secondary battery 100.

[0054] According to an embodiment of the present invention, the pouch-type battery case 110 includes cup-shaped portions 122 and 132 provided with a receiving space for accommodating electrode assemblies, a platform portion 150 formed along the periphery of the receiving portion, and at least one gas emission portion 200, wherein the gas emission portion 200 includes a through hole 220 formed in at least one of the cup-shaped portion or the platform portion, a breathable membrane 210 covering the through hole 220 from the inside of the battery case 110, and a polymer-based protective film 230 covering the through hole from the outside of the battery case 110.

[0055] (1) Bag film laminate

[0056] The pouch-type battery case 110 can accommodate the electrode assembly 160 within its internal receiving space. The pouch-type battery case 110 can be manufactured by molding a pouch film laminate. In this case, the pouch-type battery case 110 may include a substrate layer (not shown), a gas barrier layer (not shown), and a sealant layer (not shown). The substrate layer, gas barrier layer, and sealant layer can be stacked sequentially from the outside to the inside of the battery case.

[0057] A base layer is formed on the outermost layer of the bag film laminate to protect the secondary battery from external friction and impact. The base layer is made of polymer, which also allows the electrode assembly to be electrically insulated from the outside.

[0058] The base layer can be made of at least one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-benzodioxazole), polyarylate, polytetrafluoroethylene, and glass fiber. Preferably, the base layer can be made of polyethylene terephthalate (PET), nylon, or combinations thereof, which have abrasion resistance and heat resistance.

[0059] The base layer can be a single membrane structure made of any material. Alternatively, the base layer can be a composite membrane structure in which two or more materials are formed as layers.

[0060] The substrate can have a thickness of 5 μm to 50 μm, specifically 7 μm to 40 μm, and more specifically 25 μm to 38 μm. When the thickness of the substrate meets the above range, the external insulation is excellent and the entire bag is not thick, and therefore, the energy density of the secondary battery relative to its volume can be excellent.

[0061] A gas barrier layer is stacked between the base layer and the sealant layer to ensure the mechanical strength of the bag, prevent the entry and exit of external gases or moisture from the secondary battery, and prevent electrolyte leakage from the inside of the bag-type secondary battery.

[0062] The gas barrier layer can be formed of a metal, and specifically of an aluminum alloy film. When an aluminum alloy film is used to form the gas barrier layer, it can have a predetermined level of mechanical strength and is also lightweight, and can complement the electrochemical properties caused by the electrode assembly and electrolyte, and provide heat dissipation. The aluminum alloy film can include metallic elements other than aluminum (Al), for example, it can include 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).

[0063] The gas barrier layer can have a thickness of 40 μm to 100 μm, specifically 50 μm to 90 μm, and more specifically 55 μm to 85 μm. When the thickness of the gas barrier layer meets the above range, the moldability and gas barrier performance are excellent when molding the cup-shaped portion.

[0064] The sealant layer is thermally bonded together at the sealing portion when the pouch cell housing the electrode assembly is sealed, to completely seal the interior of the pouch cell. For this purpose, the sealant layer can be formed of a material with excellent heat-sealing strength.

[0065] The sealant layer can be formed of a material possessing insulating, corrosion-resistant, and sealing properties. Specifically, the sealant layer is in direct contact with the electrode components and / or electrolyte inside the pouch cell, and therefore can be formed of a material possessing both insulating and corrosion-resistant properties. Furthermore, the sealant layer should completely seal the interior of the pouch cell and prevent material movement between the interior and exterior, and therefore can be formed of a material with high sealing properties (e.g., excellent heat-sealing strength). To ensure such insulating, corrosion-resistant, and sealing properties, the sealant layer can be formed of a polymer material.

[0066] The sealant layer may be made of at least one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-benzodioxazole), polyarylate, polytetrafluoroethylene, and glass fiber, and may preferably be made of polyolefin-based resins such as polypropylene (PP) and / or polyethylene (PE). In this case, polypropylene may include cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butene-ethylene terpolymer.

[0067] The sealant layer can have a thickness of 30 μm to 130 μm, specifically 50 μm to 120 μm, and more specifically 70 μm to 100 μm. When the thickness of the sealant layer meets the above ranges, it has the effect of ensuring both the sealing strength of the sealed portion and the formability of the bag film laminate.

[0068] Meanwhile, the pouch film laminate can be drawn, molded, or stretched using a punch or the like to manufacture the pouch-type battery case 110. Therefore, the pouch-type battery case 110 may include a cup-shaped portion 122 and a receiving portion 124. The receiving portion 124 is a place for receiving electrode assemblies and may indicate the receiving space formed in the shape of a pouch inside the cup-shaped portion 122 during the molding of the cup-shaped portion 122.

[0069] According to an embodiment of the present invention, the pouch-type battery box 110 may include a first box 120 and a second box 130, such as Figure 1 As shown in the diagram, the first box 120 may include a receiving portion 124 capable of accommodating the electrode assembly 160, and the second box 130 may cover the receiving portion 124 from above to prevent the electrode assembly 160 from separating to the outside of the battery box 110. The first box 120 and the second box 130 may be as follows: Figure 1 The manufacturing shown allows one side of the first box 120 and one side of the second box 130 to be connected to each other, but embodiments of the invention are not limited thereto, and the first box 120 and the second box 130 may be manufactured differently, for example, by being manufactured separately from each other.

[0070] According to another embodiment of the invention, when forming cup-shaped portions in a bag film laminate, two symmetrical cup-shaped portions 122 and 132 can be drawn and molded adjacent to each other in one bag film laminate. In this case, cup-shaped portions 122 and 132 can be formed in the first box 120 and the second box 130, respectively, as shown. Figure 1 As shown, after the electrode assembly 160 is housed in the receiving portion 124 within the cup-shaped portion 122 of the first housing 120, the bridging portion 140 formed between the two cup-shaped portions 122 and 132 can be folded so that the two cup-shaped portions 122 and 132 face each other. In this case, the cup-shaped portion 132 of the second housing 130 can accommodate the electrode assembly 160 from above. Therefore, the two cup-shaped portions 122 and 132 accommodate one electrode assembly 160, and thus can accommodate a thicker electrode assembly 160 than when only one cup-shaped portion 122 is present. In addition, one edge of the secondary battery 100 is formed by folding the pouch-type battery case 110, and therefore, the number of edges to be sealed can be reduced when a sealing process is performed later. Therefore, the processing speed of the pouch-type secondary battery 100 can be increased, and the number of sealing processes can be reduced.

[0071] like Figure 2 As described, the pouch-type battery case 110 can be sealed while housing the electrode assembly 160, exposing a portion of the electrode leads 180, i.e., the terminal portion, which will be described later. Specifically, when the electrode leads 180 are connected to the electrode tabs 170 of the electrode assembly 160 and a lead film 190 is formed on a portion of the electrode leads 180, the electrode assembly 160 can be housed in a receiving portion 124 disposed in the cup-shaped portion 122 of the first case 120, and the second case 130 can cover the receiving portion 124 from above. Then, as described above, electrolyte is injected into the receiving portion 124, and a portion of the platform portion 150 formed along the periphery of the first case 120 and the second case 130 can be sealed to form a sealing portion 151.

[0072] The sealing portion 151 can be used to seal the receiving portion 124. Specifically, the sealing portion can seal the receiving portion 124 by forming a platform portion 150 along the periphery of the receiving portion 124.

[0073] The sealing temperature of the sealing portion 151 can be from 180°C to 250°C, specifically from 200°C to 250°C, and more specifically from 211°C to 240°C. When the sealing temperature meets the numerical range described above, the pouch-type battery box 110 can achieve sufficient sealing strength through thermal bonding.

[0074] (2) Gas emission section

[0075] According to an embodiment of the present invention, at least one gas emission portion 200 of the pouch-type battery box 110 includes a through hole formed in at least one of the cup-shaped portion or the platform portion, a breathable membrane covering the through hole from the inside of the battery box, and a polymer-based protective film covering the through hole from the outside of the battery box.

[0076] While a larger perforated area in the gas emission section 200 improves gas emission performance, increasing the area of ​​the perforations 220 for gas emission performance can adversely affect waterproofing performance. Even when performance is maximized through controlled dimensional design and materials, there are certainly significant limitations. Therefore, the present invention provides a gas emission section further provided with a polymer-based protective film covering the perforations from the outside of the battery compartment.

[0077] In the following text, reference will be made to Figures 2 to 4 The gas emission section 200 of the present invention will be described in more detail. Figure 2 This is a plan view of an example pouch-type secondary battery showing the location where the gas emission section 200 is formed. Figure 3 It is a cross-sectional view of the pouch-type secondary battery at the portion forming the gas emission section 200, and Figures 4 to 6It shows Figure 3 Enlarged cross-sectional view of the gas emission section 200.

[0078] According to an embodiment of the invention, the gas emission portion 200 may be formed at at least one location selected from the platform portion 150 and the cup-shaped portions 122 and 132 located adjacent to the platform portion 150 and having no internal contact with the electrode assembly. In this case, the cup-shaped portions 122 and 132 and the receiving portion 124 may be substantially indistinguishable in structure, and the recessed portions formed by molding in the pouch-type battery case 110 may be named the cup-shaped portions 122 and 132, and the receiving space formed by these recesses may be named the receiving portion 124.

[0079] Reference Figure 2 and Figure 3 The gas emission portion 200 may be formed in the platform portion 150 instead of the sealing portion 151, and may be formed in the cup-shaped portion 122 or the receiving portion 124 adjacent to the platform portion 150. In particular, the electrode assembly 160 is received and sealed inside the pouch battery case 110 to form the sealing portion 151, and preferably, the sealing portion 151 is formed in the cup-shaped portion 122, which is a space where the pouch battery case 110 and the electrode assembly 160 do not directly contact each other, that is, the portion of the cup-shaped portion 122 is the space where the electrode tab 170 is pulled out from the electrode assembly 160 to make electrical connection with the outside and to contact the electrode lead 180.

[0080] In this case, the gas emission section 200 can be formed as a single unit, or it can be set as two or more units. The number of gas emission sections 200 can be designed with consideration of the characteristics of the battery for internal applications, such as whether the amount of gas generated is large or small. When the polymer-based protective film 230 is provided, each gas emission section 200 can exhibit excellent moisture-proof performance, and therefore there is no particular limitation on its number.

[0081] like Figure 3 As shown, the gas emission section 200 may have a breathable membrane 210 (indicated by the dashed box) adhered to the inside of the pouch battery case 110 to seal the through-hole 220, and a polymer-based protective film 230 (indicated by the solid box) adhered to the outside of the pouch battery case 110 to secondary seal the through-hole 220. In this case, the portion of the breathable membrane 210 in contact with the pouch battery case 110 can be sealed by methods such as heat fusion, bonding / adhesion using a binder / adhesive, or bonding / adhesion using a bonding / adhesive film.

[0082] Reference Figure 4 It can be seen under magnification. Figure 3The gas emission section 200 shown, and the adhesive resin layer 211 of the breathable membrane 210 can be configured to contact the sealant layer of the pouch battery box 110.

[0083] Furthermore, according to an embodiment of the present invention, the polymer-based protective film 230 may be provided with a box-adhesive portion 231, which contacts the substrate T1 layer of the pouch-type battery case 110 around the through-hole 220. In this case, the box-adhesive portion 231 may be a portion of the polymer-based protective film 230 inserted into the battery case 110. In this case, the inserted box-adhesive portion 231 can be bonded to the pouch-type battery case 110 and serves as a single resin layer, which can effectively block moisture from the outside.

[0084] At the same time, refer to Figure 5 ,and Figure 4 Unlike other embodiments of the present invention, the gas emission portion 200 can form a membrane bonding portion 232 in the area where the breathable membrane 210 contacts the polymer-based protective membrane 230. That is, the polymer-based protective membrane 230 covers the through-hole 220 from the outside of the battery case 110, but the polymer-based protective membrane 230 in the through-hole 220 can be designed to be inserted into the through-hole and contact the breathable membrane 210 covering the through-hole 220 from the inside. In this case, the gas emission portion 200 can be formed by sealing (via thermal fusion, bonding / adhesion, etc.) the partial or complete area where the polymer-based protective membrane 230 and the breathable membrane 210 contact. In this case, the gas emission performance can be controlled according to the area of ​​the membrane bonding portion 232, and moisture penetration can also be prevented due to the remaining portion of the polymer-based protective membrane 230 protruding from the membrane bonding portion 232 to the outside of the through-hole 220.

[0085] Additionally, refer to Figure 6 According to an embodiment of the invention, the gas emission portion 200 may be provided with a polymer-based protective film 230 precisely designed to match the size of the through-hole 220. Although the film bonding portion 232 may be formed in the area in contact with the breathable membrane 210, the area to be sealed may be smaller compared to the case where the area of ​​the polymer-based protective film 230 is larger than that of the through-hole 220.

[0086] In this case, the area to be sealed, i.e. the area of ​​the membrane bonding portion 232, can be appropriately controlled, and the gas emission portion 200 can be designed according to the battery components installed inside, such as the positive electrode, negative electrode, or electrolyte components, or according to the intended use of the battery, taking into account the required gas emission performance.

[0087] Therefore, according to embodiments of the present invention, the area of ​​the polymer-based protective film 230 can be greater than or equal to the area of ​​the through-hole 220, and the area of ​​the film adhesive portion 232 can be less than or equal to the area of ​​the through-hole 220. Preferably, the area of ​​the polymer-based protective film 230 can be 100% to 200% of the area of ​​the through-hole 220, and the area of ​​the film adhesive portion 232 can be 50% to 100%, more preferably 50% to 90% or 50% to 85%, and most preferably 50% to 80% of the area of ​​the through-hole 220.

[0088] like Figures 3 to 6 As shown, when the gas emission portion 200, in which the through-holes 220 are formed, is covered from the inside and outside of the battery box to prevent moisture penetration, moisture permeability can be improved without reducing gas emission performance. Furthermore, the material can be designed to function not only as a polymer-based protective film 230 but also as a breathable film 210, which is an effective method to reduce moisture penetration while minimizing the decline in gas emission performance. Preferably, as... Figure 4 As shown, forming a polymer-based protective film 230 can further maximize the effect of preventing moisture penetration, and Figure 4 In the case of this structure, there is a space between the breathable membrane 210 and the polymer-based protective membrane 230 that serves as an air pocket; therefore, the reduction in gas emission performance can be minimized compared to the case where the polymer-based protective membrane 230 is not applied. When adhered to, such as Figure 4 When the pouch-type battery box 110 shown is used, a sealing effect similar to that achieved by heat-sealing or by adhesive sealing can be expected.

[0089] According to embodiments of the present invention, the polymer-based protective film 230 can be made of a variety of materials. For example... Figure 5 or Figure 6 As shown, when forming the breathable membrane 210 and the adhesive portion 232, it is preferable to use the same type of material as the breathable membrane 210, especially the adhesive resin layer 211 on the side in contact with the battery compartment.

[0090] The polymer-based protective film 230 may include at least one material selected from, for example, polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylenebenzobisazole), polyarylate, polytetrafluoroethylene, fluorinated ethylene propylene copolymer, perfluoroalkoxy-substituted polytetrafluoroethylene, ethylene tetrafluoroethylene copolymer, and glass fiber. Preferably, it may include polyolefin resins such as polypropylene (PP) and / or polyethylene (PE), or fluoropolymers such as polytetrafluoroethylene, fluorinated ethylene propylene copolymer, perfluoroalkoxy-substituted polytetrafluoroethylene, and ethylene tetrafluoroethylene copolymer, and more preferably, it may include fluoropolymers such as polytetrafluoroethylene, fluorinated ethylene propylene copolymer, perfluoroalkoxy-substituted polytetrafluoroethylene, and ethylene tetrafluoroethylene copolymer. In this case, the polypropylene may include cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butene-ethylene terpolymer.

[0091] Acid-modified polyolefins can be obtained by introducing carboxyl groups (grafting modification) through the reaction of unsaturated carboxylic acids with polyolefin resins. In this case, the unsaturated carboxylic acid can include the concept of carboxylic anhydride, and the carboxyl group can include the concept of a carboxylic anhydride group. The unsaturated carboxylic acid reacting with the polyolefin resin can include, but is not limited to, at least one selected from maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaric acid, tetrahydrophthalic acid, aconitic acid, maleic anhydride, itaconic anhydride, glutaric anhydride, citraconic anhydride, aconitic anhydride, norbornene anhydride, and tetrahydrophthalic anhydride.

[0092] Silane-modified polyolefins refer to polyolefin resins grafted with unsaturated silane compounds. Silane-modified polyolefins may have a structure in which unsaturated silane compounds are grafted copolymerized onto a polyolefin resin as the main chain. Silane-modified polyolefin resins may include, but are not limited to, at least one selected from silane-modified polypropylene resins and silane-modified ethylene-vinyl acetate copolymers.

[0093] In addition, although Figures 4 to 6Although not shown, the polymer-based protective film 230 can be formed into a multilayer structure. For example, a sealing layer can be provided in the portions forming the adhesive portions 231 and 232, a barrier layer can be provided on the sealing layer, and at least one separate intermediate layer can be included between the sealing layer and the barrier layer. Forming such a multilayer structure may be more advantageous because it allows for a configuration including layers of hot-melt resin when the polymer-based protective film is sealed using heat fusion. For example, in the case of attaching a polyethylene terephthalate film or a polyimide film to a pouch battery case by means of an adhesive film or adhesive, a single layer of polymer-based protective film can be applied in addition to the adhesive layer, and in the case of using heat fusion, a multilayer polymer-based protective film bonded to a fusible material such as polypropylene or polyethylene can be applied.

[0094] Furthermore, according to embodiments of the present invention, the polymer-based protective film may include a waterproof coating on the surface exposed to the outside of the battery case, and may independently include ceramic filler inside.

[0095] Waterproof coatings can significantly improve the performance of blocking external moisture. For example, waterproof coatings can be formed by controlling the contact angle of the barrier layer surface exposed to the outside, forming a coating on the barrier layer using a hydrophobic material, or applying a barrier layer that acts as a hydrophobic material. This contact angle can be achieved by controlling surface irregularities through injecting filler into the barrier layer, or by controlling the roughness of the rollers during the extrusion of the barrier layer.

[0096] Furthermore, when ceramic fillers are included in polymer-based protective films, they can absorb incoming moisture and byproducts generated by moisture, such as hydrogen fluoride (HF). They can also enhance the film's strength, thereby improving its ability to prevent damage from external physical factors. Ceramic fillers can be included in at least one layer of the multilayer structure constituting the polymer-based protective film and can be added to control the irregularity of the barrier layer surface. However, the location of the layer in which the ceramic filler is added may not be particularly limited if the content is controlled at a level that does not reduce the film's durability; however, for effective removal of moisture and moisture-generated byproducts, it is preferable to include ceramic fillers in the inner layers.

[0097] The ceramic filler may include at least one selected from CaCO3, Ca(OH)2, CaCl2, CaO, KOH, NaOH and Na2CO3, preferably CaCO3.

[0098] Meanwhile, according to embodiments of the present invention, such as Figures 4 to 6 As shown, the gas emission section 200 includes an adhesive resin layer 211 that contacts the pouch-type battery box 110 and a permeable resin layer 212 disposed on the adhesive resin layer 211.

[0099] The adhesive resin layer 211 contacts the pouch-type battery case 110 and is intended to bond the gas emission portion 200 to the pouch-type battery case 110, and may include any material that facilitates bonding to the pouch-type battery case 110. Specifically, the adhesive resin layer 211 may comprise a non-fluorinated polyolefin resin, and preferably may comprise a modified polyolefin resin.

[0100] When the adhesive resin layer 211 includes a modified polyolefin resin, the adhesive strength between the gas venting portion 200 and the pouch battery box 110 is increased, and therefore, even when the pouch secondary battery is stored in a high-temperature environment, the gas venting portion 200 can be prevented from detaching from the pouch battery box 110, thereby preventing electrolyte leakage and moisture penetration inside the pouch.

[0101] For example, the adhesive resin layer 211 may include at least one of an acid-modified polyolefin or a silane-modified polyolefin.

[0102] Acid-modified polyolefins refer to polyolefin resins that have been grafted with acid. For example, acid-modified polyolefins can be obtained by reacting an unsaturated carboxylic acid with a polyolefin resin to introduce carboxyl groups (grafting modification). In this case, the unsaturated carboxylic acid can include the concept of a carboxylic anhydride, and the carboxyl group can include the concept of a carboxylic anhydride group. The unsaturated carboxylic acid undergoing reaction with the polyolefin resin can include, but is not limited to, at least one selected from maleic acid, fumaric acid, itaconic acid, citraconic acid, pentadienoic acid, tetrahydrophthalic acid, aconitic acid, maleic anhydride, itaconic anhydride, pentadienoic anhydride, citraconic anhydride, aconitic anhydride, norbornene dicarboxylic anhydride, and tetrahydrophthalic anhydride. In particular, maleic anhydride is preferably applied to improve the adhesion between the gas emission section 200 and the electrode lead 180. Acid-modified polyolefins can include, but are not limited to, at least one selected from acid-modified polypropylene (PPa) and acid-modified polyethylene (PEa).

[0103] Silane-modified polyolefins refer to polyolefin resins grafted with unsaturated silane compounds. Silane-modified polyolefins may have a structure in which the unsaturated silane compound is graft copolymerized with a polyolefin resin as the main chain. Silane-modified polyolefin resins may include, but are not limited to, at least one selected from silane-modified polypropylene resins and silane-modified ethylene-vinyl acetate copolymers.

[0104] The adhesive resin layer 211 can be modified, and examples of modification treatments include ion implantation, plasma treatment, irradiation treatment, heat treatment, etc., and preferably treatments that change the bonding structure of the polymer layer. These modification treatments can be performed alone or in combination of two or more types. The modified adhesive resin layer 211 may include, but is not limited to, plasma-treated polypropylene (PP).

[0105] The thickness of the adhesive resin layer 211 can be from 20 μm to 250 μm, specifically from 30 μm to 200 μm, and more specifically from 30 μm to 150 μm. When the thickness of the adhesive resin layer 211 meets the above numerical range, the adhesive resin layer 211 melts within a specified cycle time, and accordingly, the gas emission portion 200 and the pouch-type battery box 110 can be easily fused together.

[0106] According to an embodiment of the present invention, the permeable resin layer 212 may be a layer that contacts the adhesive resin layer 211 to facilitate gas discharge.

[0107] The permeable resin layer 212 may include a fluorinated polyolefin resin, and preferably may include at least one of polytetrafluoroethylene (PTFE) or polyimide (PI).

[0108] The thickness of the permeable resin layer 212 can be from 30 μm to 200 μm, specifically from 40 μm to 150 μm, and more specifically from 45 μm to 100 μm. When the thickness of the permeable resin layer 212 meets the above numerical range, the gas venting function can be performed smoothly even when the internal pressure of the pouch battery box 110 increases, without the gas venting section 200 detaching due to ventilation.

[0109] Meanwhile, according to embodiments of the present invention, the breathable membrane 210 may have a thickness (T) of 80 μm to 500 μm, specifically 80 μm to 450 μm, 80 μm to 400 μm, 90 μm to 350 μm, and more preferably 100 μm to 300 μm. F When the above range is met, the thickness ratio of the adhesive resin layer 211 and the permeable resin layer 212 constituting the breathable membrane 210 can be easily adjusted, thereby facilitating designs that take into account adhesive strength and gas emission performance.

[0110] The thickness of the adhesive resin layer 211 (T) A ) and the thickness (T) of the permeable resin layer 212 T The ratio of (T) A / T T The ratio (T) can be 0.4 to 2.0, specifically 0.4 to 1.5, more specifically 0.4 to 1.2, and preferably 0.5 to 1.0. When the above ratio (T) A / T T When the above numerical range is met, the following gas venting section 200 can be easily implemented, which can vent gas while maintaining adhesive strength, without causing permanent damage to the gas venting section 200 due to ventilation and minimizing the pressure when the gas venting section 200 starts operating, and can be expected to meet the above range when designing the moisture resistance index.

[0111] Therefore, the pouch-type secondary battery case according to an embodiment of the present invention has a gas venting section as described above, and thus can significantly improve the performance in preventing electrolyte leakage and moisture penetration while maintaining a satisfactory gas venting performance level. This prevents corrosion caused by the generated gas or by moisture penetration or electrolyte leakage, thereby contributing to increased lifespan due to increased durability. The battery's driving performance can be maintained through continuous gas venting, and the risk of explosion due to expansion is also reduced, thereby ensuring safety.

[0112] pouch-type secondary batteries

[0113] According to another embodiment of the present invention, a pouch-type secondary battery 100 is provided, the pouch-type secondary battery 100 including an electrode assembly 160, a pouch-type battery case 110 as described above, an electrode lead 180 connected to the electrode assembly 160 and protruding to the outside of the pouch-type case 110 via a platform portion 150, and a lead film 190 disposed on the platform portion 150 between the electrode lead 180 and the pouch-type case 110, wherein a portion of the platform portion 150 is sealed along the periphery of the cup-shaped portions 122 and 132 to form a sealing portion 151.

[0114] The descriptions of the pouch-type battery case 110 and the gas emission section 200 disposed within the pouch-type battery case 110 are repeated from those described above, and therefore their descriptions will be skipped. Other components included in the pouch-type secondary battery 100 will be described below.

[0115] (1) Electrode assembly

[0116] According to an embodiment of the present invention, the electrode assembly 160 can be housed in the receiving portion 124 of the pouch-type battery box 110 and sealed by a sealing portion 151, which is formed by thermal fusion of the platform portion 150 after electrolyte injection.

[0117] The positive electrode, the separator, and the negative electrode can be stacked sequentially to form an electrode assembly 160. Specifically, the electrode assembly 160 may include both positive and negative electrodes, and includes a separator sandwiched between the electrodes to insulate them from each other.

[0118] The positive and negative electrodes can have the following structure: an active material slurry is applied to an electrode current collector in the form of a metal foil or mesh containing aluminum and copper, respectively. Typically, granular active material, auxiliary conductor, binder, and conductive material are stirred together with an added solvent to form a slurry. The solvent can be removed in subsequent processing.

[0119] A slurry mixed with electrode active materials, binders, and / or conductive materials can be applied to positive and negative current collectors to manufacture positive and negative electrodes, which are stacked on both sides of a separator, thereby enabling the electrode assembly 160 to be manufactured into a predetermined shape. The type of electrode assembly 160 may include, but is not limited to, stacked, wound, and stacked and folded types.

[0120] Electrode assembly 160 may include electrode tabs 170.

[0121] Reference Figure 1 Electrode tab 170 is connected to each of the positive and negative electrodes of electrode assembly 160 and protrudes outward from electrode assembly 160, thus serving as a path for electrons to move between the inside and outside of the electrode tab. The current collector included in electrode assembly 160 may have a portion to which electrode active material is applied and an end portion to which no electrode active material is applied, i.e., an uncoated portion. Electrode tab 170 can be formed by cutting the uncoated portion, or by connecting individual conductive members to the uncoated portion using methods such as ultrasonic welding. Figure 1 As shown, electrode tab 170 can protrude from electrode assembly 160 in different directions, but is not limited thereto, and can be formed to protrude in various directions, such as protruding from one side in the same direction.

[0122] (2) Electrode leads

[0123] According to an embodiment of the present invention, the electrode lead 180 can supply power to the outside of the secondary battery 100. The electrode lead 180 can be connected to the electrode contacts 170 of the electrode assembly 160 by spot welding or the like.

[0124] Reference Figure 1 and Figure 3 The electrode lead 180 can be connected to the electrode assembly 160 and can protrude to the outside of the pouch battery case 110 via the platform portion 150. Specifically, one end of the electrode lead 180 can be connected to the electrode assembly 160, particularly to the electrode tab 170, and the other end of the electrode lead 180 can protrude to the outside of the pouch battery case 110 via the platform portion 150.

[0125] Electrode leads 180 may include a positive lead 182 and a negative lead 184. One end of the positive lead 182 is connected to the positive terminal 172 and extends in the direction in which the positive terminal 172 protrudes. One end of the negative lead 184 is connected to the negative terminal 174 and extends in the direction in which the negative terminal 174 protrudes. The other ends of both the positive lead 182 and the negative lead 184 may protrude to the outside of the battery case 110. Therefore, power generated inside the electrode assembly 160 can be supplied to the outside. Furthermore, the positive terminal 172 and the negative terminal 174 are each formed to protrude in various directions, and therefore, the positive lead 182 and the negative lead 184 may also extend in various directions. The positive lead 182 and the negative lead 184 may be made of different materials. In other words, the positive electrode lead 182 can be made of the same aluminum (Al) material as the positive current collector, and the negative electrode lead 184 can be made of the same copper (Cu) or nickel (Ni) coated copper material as the negative current collector. The portion of the electrode lead 180 protruding to the outside of the battery case 110 can be used as a terminal portion and electrically connected to an external terminal.

[0126] The side of the electrode lead 180 that is in direct contact with the lead film 190 and / or the gas emission portion 200 may be coated with at least one selected from chromium (Cr), nickel (Ni), alumina (Al2O3), zirconium (Zr)-based anhydride salts, and titanium (Ti)-based anhydride salts. In this case, corrosion resistance to the electrolyte solution and adhesion to the lead film 190 and / or the gas emission portion 200 can be obtained.

[0127] (3) Lead film

[0128] According to an embodiment of the invention, the lead film 190 prevents electricity generated from the electrode assembly 160 from flowing through the electrode leads 180 to the battery case 110, and allows the battery case 110 to remain sealed. For this purpose, the lead film 190 can be formed of a non-conductor having non-conductive properties in which current cannot flow well. Typically, a relatively thin insulating strip that is easily attached to the electrode leads 180 and / or the gas vent portion 200 is widely used as the lead film 190; however, embodiments of the invention are not limited to this, and therefore any component capable of insulating the electrode leads 180 can be used.

[0129] The lead film 190 can be configured to surround the outer peripheral surface of the electrode lead 180. The lead film 190 can be positioned within the platform portion 150 where the sealing portions 151 of the first box 120 and the second box 130 of the pouch-type battery box 110 are heat-fused, and can allow the electrode lead 180 to be bonded to the battery box 110.

[0130] The lead film 190 can be disposed between the electrode lead 180 and the pouch-type battery case 110. For example, as... Figure 3 As shown, the lower box 110, lead film 190, electrode lead 180, lead film 190 and upper box 110 can be stacked and arranged in the platform portion 150 in this order.

[0131] Meanwhile, the lead film 190 may include at least one layer. Specifically, the lead film 190 may include a metal adhesive layer, a core layer, and a pouch adhesive layer stacked sequentially.

[0132] The metal adhesive layer is in direct contact with the electrode lead 180 and can be used to adhere the lead film 190 to the electrode lead 180. The metal adhesive layer can comprise any material that readily adheres to the electrode lead 180. Specifically, the metal adhesive layer can comprise an acid-modified polyolefin. For example, the metal adhesive layer can comprise at least one of acid-modified polypropylene (PPa), acid-modified polyethylene (PEa), or plasma-treated polypropylene (PP), but is not limited thereto. The metal adhesive layer can have a thickness of 50 μm to 80 μm, specifically 50 μm to 75 μm, more specifically 60 μm to 75 μm. When the thickness of the metal adhesive layer meets the above numerical range, it has the effect of preventing pinhole penetration and leakage at the edge portions during the fusion between the electrode lead and the lead film.

[0133] The core layer may be a layer disposed in the center of the lead film 190. The core layer may include, but is not limited to, additives such as polypropylene, polyolefin elastomer (POE), and / or colorants. In particular, the polymer contained in the core layer may be a homopolymer. When a homopolymer is included in the core layer, the melting point of the core layer can be controlled within the aforementioned numerical range, and heat-induced deformation can be minimized, which is better for ensuring insulation. The core layer may have a thickness of 40 μm to 70 μm, specifically 50 μm to 70 μm, and more specifically 60 μm to 70 μm. When the thickness of the core layer meets the aforementioned numerical range, deformation caused by heat applied during fusion and sealing can be prevented, thereby providing a stable design effect in ensuring insulation.

[0134] The bag adhesive layer can be a layer in direct contact with the battery compartment 110, specifically a sealant layer of the bag film laminate. The bag adhesive layer can include, but is not limited to, polypropylene or polyolefin elastomer (POE). In particular, the polymer contained in the bag adhesive layer can be a copolymer. The melting point of the bag adhesive layer containing the copolymer can be controlled within the aforementioned numerical range, and the bag adhesive layer has a melting point similar to that of the polymer in the sealant layer of the bag film laminate, which is better for ensuring sealable processability. The bag adhesive layer can have a thickness of 40 μm to 100 μm, specifically 40 μm to 80 μm, more specifically 40 μm to 60 μm. When the thickness of the bag adhesive layer meets the aforementioned numerical range, it has the effect of ensuring that the residual amount of polymer (e.g., polypropylene) is sufficient to obtain the strength required for sealing between the electrode leads and the bag film laminate.

[0135] (4) Electrolytes

[0136] The pouch-type secondary battery 100 according to the invention may further include an electrolyte (not shown) injected into the pouch-type battery case 110. The electrolyte is used to move lithium ions generated by electrochemical reactions at the electrodes during charging / discharging of the secondary battery 100, and may comprise a non-aqueous organic electrolyte solution as a mixture of lithium salt and organic solvent, or a polymer electrolyte. Additionally, the electrolyte may include a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a polymer-based solid electrolyte, and such solid electrolyte may be flexible and therefore easily deformable under external force.

[0137] Battery box

[0138] According to an embodiment of the present invention, a battery case including a pouch-type secondary battery is provided. The battery case according to the embodiment of the present invention may include a pouch-type secondary battery and a packaging component therein containing the pouch-type secondary battery. The pouch-type secondary battery may be configured to charge and discharge, and in this case, the pouch-type secondary battery may be the secondary battery described above according to the embodiment of the present invention.

[0139] To increase the capacity or voltage of the battery box, multiple pouch-type secondary batteries can be constructed. These multiple pouch-type secondary batteries can be arranged in a predetermined manner, for example, they can be stacked in one direction, but the arrangement of the pouch-type secondary batteries is not particularly limited.

[0140] The packaging can be configured to house the secondary battery and protect it from external contamination or impact. For example, the packaging can have a shell shape, but there are no particular restrictions on the structure or shape of the packaging, as long as it can accommodate the secondary battery.

[0141] Furthermore, according to embodiments of the present invention, for the operation or safety of the battery box, components performing predetermined functions can be installed in the packaging. For example, the packaging may also be equipped with connectors or busbars for electrically connecting the secondary battery to the outside, and vent plugs for connecting the inside and outside of the packaging.

[0142] The battery box can be used to include, for example, battery modules or battery packs, and can include a package and battery cells, wherein multiple secondary batteries are housed within the package.

[0143] The invention will be described in more detail below through specific embodiments. However, the examples shown below are for illustrative purposes only, and the scope of the inventive concept is not limited thereto. It will be apparent to those skilled in the art that various modifications and alterations can be made within the scope and technical range of the invention, and that such modifications and alterations fall within the scope of the claims contained herein.

[0144] Examples and Comparison Examples

[0145] Example 1

[0146] (1) Manufacturing of pouch-type battery boxes

[0147] A bag film laminate with a polyethylene terephthalate (PET) film and a nylon film of 266 mm width, 50 m length, and 60 μm thickness are stacked on one side of an aluminum alloy film. The PET film has a width of 266 mm, a length of 50 m, and a thickness of 12 μm, and the nylon film has a width of 266 mm, a length of 50 m, and a thickness of 25 μm. A polypropylene film with a width of 266 mm, a length of 50 m, and a thickness of 80 μm is stacked on the other side of the aluminum alloy film. In this case, the PET film and nylon film are the base layers, the aluminum alloy film is the gas barrier layer, and the polypropylene film is the sealant layer.

[0148] The pouch film laminate is molded into a pouch-shaped battery case comprising a receiving portion and a platform portion, such as... Figure 3 As shown, through holes are formed in the receiving portion (cup-shaped portion) adjacent to the platform portion, a breathable membrane is thermally fused inside the pouch-shaped battery box, and a polymer-based protective film is thermally fused to the outside of the pouch-shaped battery box to form a structure having... Figure 3 The gas emission section of the structure shown.

[0149] In this case, the breathable membrane used is a membrane composed of a 100 μm thick acid-modified polypropylene (PPa) as the adhesive resin layer and a 100 μm thick polytetrafluoroethylene (PTFE) as the permeable resin layer, and the polymer-based protective membrane used is an 80 μm thick polytetrafluoroethylene (PTFE) tape.

[0150] (2) Manufacturing of pouch-type secondary batteries

[0151] The negative electrode, positive electrode, and porous polyethylene separator are assembled using a stacking method and then laminated to manufacture the electrode assembly. Electrode leads are then connected to the electrode assembly.

[0152] LiPF6 was dissolved in a solvent (EC:EMC:DMC = 3:3:4, volume ratio) to prepare a 1.0 M electrolyte. The electrode assembly was housed in a pouch cell, wherein the front ends of the electrode leads protrude outwards and are injected with electrolyte.

[0153] Then, a 200 μm thick lead film is stacked on each of the lower surface of the electrode leads and the upper surface of the gas emission section. The lead film may include a 75 μm thick metal adhesive layer of copolymer polypropylene and acid-modified polypropylene, a 65 μm thick core layer of homopolymer polypropylene, and a 60 μm thick bag adhesive layer of copolymer polypropylene.

[0154] Subsequently, the sealed portion of the pouch-type battery box was sealed for 2 seconds under conditions of a sealing strip area of ​​200 mm × 10 mm, 212°C, and 0.27 MPa, and then placed at 60°C for 4 hours to manufacture the pouch-type secondary battery.

[0155] Example 2

[0156] The pouch-type secondary battery is manufactured in the same manner as in Example 1, except that an 80 μm thick cast polypropylene (cPP) strip (acrylic polymer-based adhesive) is used as a polymer-based protective film to apply a seal via adhesive rather than heat-melting to form a gas emission portion.

[0157] Example 3

[0158] The pouch-type secondary battery is manufactured in the same manner as in Example 1, except that an 80 μm thick cast polypropylene (cPP) strip (natural rubber (isoprene) based adhesive) is used as a polymer-based protective film to apply a seal via adhesive rather than heat-melting to form a gas emission portion.

[0159] Comparison Example 1

[0160] The pouch-type secondary battery is manufactured in the same manner as in Example 1, except that no polymer-based protective film is applied to form the gas emission portion.

[0161] Comparison Example 2

[0162] The pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a 1013 μm thick acrylic double-sided tape (3M, 4910 vhb) was used as a polymer-based protective film to apply a seal via adhesive rather than heat-melting to form a gas venting section.

[0163] Comparison Example 3

[0164] The pouch-type secondary battery is manufactured in the same manner as in Example 1, except that a 50 μm thick aluminum foil (acrylic polymer-based adhesive) is used as a polymer-based protective film to apply a seal via adhesive rather than heat fusion to form a gas emission section.

[0165] Experimental Example 1: Assessment of Gas Emissions

[0166] The properties of the breathable membrane were determined and its performance evaluated using the following methods for the following items.

[0167] 1) Observation of gas emission rate (cc / day) and detachment: Using the internal pressure device of ITS, CO2 was injected into the pouch cell to increase the internal pressure to 1.5 atm or 2.0 atm, and then the gas emission was measured at 60°C for 24 hours. It was observed whether the polymer-based protective film detached due to cell deformation caused by the increase in internal pressure. The results are shown in Table 1 below.

[0168] 2) HF concentration (ppm): The pouch cell was placed at 60°C and 90% relative humidity for one week. Then, the cell was opened, and 20 g of electrolyte was collected to measure the HF concentration (wt pp) to assess the degree of moisture penetration. The results are shown in Table 1 below.

[0169] 3) Tensile Strength (N / 15 mm): The polymer-based protective film was cut into 15 mm (MD) × 10 mm (TD) dimensions. Then, using a UTM (Universal Testing Machine) from ZwickRoell, the protective film was clamped between the upper and lower fixtures of the upper fixture box according to ASTM D638 and stretched at a speed of 5 mm / min with a gap of 30 mm to determine the maximum force (N) applied to the point of breakage. Typically, tensile strength is measured in N / mm². 2 However, in this case, without considering the thickness of each membrane, the maximum force at the breaking point of a 15 mm long sample was measured, so the unit is expressed as N / 15 mm.

[0170] [Table 1]

[0171]

[0172] According to Table 1 above, in the case of Example 1, the gas emission rate was not significantly different from that of Comparative Example 1 without the polymer-based protective film. However, when the polymer-based protective film was not applied, the HF concentration was found to be significantly increased compared to the implementation with the applied HF concentration. For reference, in the case of gas emission rate, the emission amount over 24 hours was measured in cc, so the difference between the example and the comparative example was not significant. However, HF concentration is an important factor that needs to be controlled because when the HF concentration exceeds a certain level, the battery performance itself may rapidly decline.

[0173] In addition, compared to the examples, the membrane of Comparative Example 2, i.e., the double-sided strip, is thick enough to prevent moisture penetration to some extent and also shows satisfactory gas emission performance, but shows low tensile strength, indicating that it is not commercially feasible. Comparative Example 3, which has been found to use aluminum foil, shows high tensile strength, but the material itself lacks flexibility, which prevents it from adapting to deformation, such as expanding the pouch battery box, leading to detachment.

[0174] In contrast, Examples 1 to 3, which have been found to use polymer-based protective films, can maximize gas emission performance, prevent moisture penetration, maintain a certain level or higher tensile strength, and adapt to the deformation of the pouch-shaped battery box through the flexibility of the material itself.

[0175] [Explanation of reference numerals in the attached figures]

[0176] 100: Pouch-type secondary battery

[0177] 110: Pocket-type battery box

[0178] 120: First box

[0179] 122: Cup-shaped part

[0180] 124: Containment section

[0181] 130: Second box

[0182] 132: Cup-shaped part

[0183] 140: Bridging section

[0184] 150: Platform Section

[0185] 151: Sealing part

[0186] 160: Electrode assembly

[0187] 170: Electrode contacts

[0188] 172: Positive electrode connector

[0189] 174: Negative electrode connector

[0190] 180: Electrode lead

[0191] 182: Positive lead

[0192] 184: Negative lead

[0193] 190: Lead film

[0194] 200: Gas Emission Section

[0195] 210: Breathable membrane

[0196] 211: Adhesive resin layer

[0197] 212: Permeable resin layer

[0198] 220: Through hole

[0199] 230: Polymer-based protective film

[0200] 231: Box adhesive part

[0201] 232: Membrane bonding section

Claims

1. A pouch-type battery box, comprising: The cup-shaped portion has a receiving space for accommodating the electrode assembly; The platform portion is formed along the periphery of the receiving portion; as well as At least one gas emission section, Each of the gas emission sections includes: A through-hole, wherein the through-hole is formed in at least one of the cup-shaped portion or the platform portion; A breathable membrane, the breathable membrane covering the through-hole from the inside of the battery compartment; and A polymer-based protective film covers the through-hole from the outside of the battery compartment.

2. The pouch-type battery box according to claim 1, wherein, The polymer-based protective film includes at least one selected from polypropylene, polyethylene, polytetrafluoroethylene, fluorinated ethylene propylene copolymer, perfluoroalkoxy-substituted polytetrafluoroethylene, and ethylene tetrafluoroethylene copolymer.

3. The pouch-type battery box according to claim 1, wherein, The polymer-based protective film has a box-adhesive portion surrounding the through-hole and in contact with the battery case, and A portion of the polymer-based protective film is inserted into the battery compartment at the adhesive portion of the compartment.

4. The pouch-type battery box according to claim 1, wherein, The polymer-based protective film is provided with a film bonding portion that contacts the breathable film within the through-hole.

5. The pouch-type battery box according to claim 4, wherein, The area of ​​the polymer-based protective film is greater than or equal to the area of ​​the through-hole, and the area of ​​the film adhesive portion is less than or equal to the area of ​​the through-hole.

6. The pouch-type battery box according to claim 1, wherein, The polymer-based protective film includes a waterproof coating on the surface exposed to the outside of the battery box.

7. The pouch-type battery box according to claim 1, wherein, The polymer-based protective film includes ceramic fillers.

8. The pouch-type battery box according to claim 7, wherein, The ceramic filler includes at least one selected from CaCO3, Ca(OH)2, CaCl2, CaO, KOH, NaOH, and Na2CO3.

9. The pouch-type battery box according to claim 1, wherein, The breathable membrane includes an adhesive resin layer surrounding the through-hole and in contact with the battery compartment, and a permeable resin layer disposed on the adhesive resin layer.

10. The pouch-type battery box according to claim 9, wherein, The adhesive resin layer comprises a non-fluorinated polyolefin-based resin.

11. The pouch-type battery box according to claim 9, wherein, The permeable resin layer comprises a fluorinated polyolefin-based resin.

12. The pouch-type battery box according to claim 1, wherein, The gas emission portion is formed at at least one location selected from the platform portion and the cup-shaped portion located adjacent to the platform portion and having no internal contact with the electrode assembly.

13. The pouch-type battery box according to claim 1, wherein, The gas emission section is configured such that the adhesive resin layer contacts the pouch-shaped battery box.

14. A pouch-type secondary battery, comprising: Electrode assembly; The pouch-type battery box according to claim 1; Electrode leads are connected to the electrode assembly and protrude to the outside of the pouch-shaped battery compartment via the platform portion; as well as A lead film is disposed on the platform portion between the electrode leads and the pouch-shaped battery compartment. A portion of the platform section is sealed along the periphery of the cup-shaped section to form a sealed portion.

15. A battery box, comprising: Multiple pouch-type secondary batteries according to claim 14; as well as A package for containing the pouch-type secondary battery.

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