Pouch-type battery case and pouch-type secondary battery comprising same

Abstract

The pouch-type battery case according to the present invention may comprise a cup part having an accommodation space in which an electrode assembly is accommodated, a terrace part formed along the periphery of the accommodation part, and one or more gas discharge parts, wherein each of the gas discharge parts includes: a through-hole formed in at least one of the cup part and the terrace part; a gas-permeable film disposed on the inner side of the battery case to cover the through-hole; and a polymer protective film disposed on the outer side of the battery case to cover the through-hole. The gas discharge part configured as described above enables continuous discharge of gas while exhibiting excellent performance in preventing moisture penetration from the outside, thereby providing a pouch-type secondary battery having improved safety and lifespan.

Description

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

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0045610, filed April 3, 2024, the entire contents of which are incorporated herein by reference.

[0003]

[0004] Technology field

[0005] The present invention relates to a pouch-type battery case and a pouch-type secondary battery including the same, and more particularly, to a pouch-type battery case including a gas discharge unit with excellent moisture blocking performance and a pouch-type secondary battery including the same.

[0006]

[0007] Secondary batteries are used in a wide range of applications, from small products like digital cameras, DVDs, MP3 players, mobile phones, PDAs, portable game devices, power tools, and e-bikes, to larger, high-power products like electric and hybrid vehicles, as well as power storage devices that store surplus power or renewable energy, and as backup power storage devices. Types of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries.

[0008] Secondary batteries can be manufactured by housing an electrode assembly, in which a positive electrode, a negative electrode, and a separator interposed therebetween are alternately laminated, in a battery case, injecting an electrolyte, and then sealing the battery case. Secondary batteries are classified into pouch types and can types depending on the material of the case housing the electrode assembly. Among them, pouch type batteries can be manufactured by performing press processing on a flexible pouch film laminate to form a cup portion, housing the electrode assembly in the inner space of the cup portion, and sealing the seal portion.

[0009] Pouch-type secondary batteries can generate gas within the pouch during high-temperature operation, overcharging, or short-circuiting. If the gas pressure within the pouch increases, the pouch can vent, potentially leading to explosion or ignition. To address this issue, a component capable of continuously releasing gas without interrupting battery operation is essential.

[0010] In order to discharge the gas generated inside the battery, active research is being conducted on installing a gas discharge component configured as a valve. However, most valve-type gas discharge components are composed of heavy materials, and the problem of swelling due to gas generation is often not resolved due to high operating pressure.

[0011] Accordingly, a gas discharge component is being developed that prevents the movement of moisture and electrolyte while allowing only gas to pass through by deforming the lead film of the electrode lead portion or forming a hole by punching a portion of the battery case and then sealing it with a film that only allows gas to pass through.

[0012] However, in the case of a film that is permeable only to gas as described above, depending on the material applied, if the gas permeability is excellent, the possibility of liquid penetration also increases, and adhesion to the battery case may be a problem, and if the possibility of liquid penetration is attempted to be zero, there is a problem that the desired level of gas discharge performance is not achieved.

[0013] In addition, there is a problem that gas discharge performance or liquid blocking performance varies depending on the dimensional characteristics of the components that make up the gas discharge part, and since it has not been clearly identified what dimensions are variables that can affect gas discharge performance, in-depth research is required to implement a gas discharge part with excellent performance.

[0014]

[0015] The present invention is intended to solve the above-mentioned problems, and provides a pouch-type battery case having excellent performance in blocking moisture while allowing gas to be discharged well by designing it to include a polymer-based protective film covering the through hole from the outside of the battery case in addition to a through hole connecting the inside and outside of the case constituting the gas discharge portion and a gas-permeable film covering the through hole from the inside.

[0016] In addition, the present invention is intended to solve the above-mentioned problems, and to provide a pouch-type secondary battery with excellent safety and improved lifespan by applying the pouch-type battery case.

[0017]

[0018] [1] According to one embodiment of the present invention, a pouch-type battery case is provided, which includes a cup portion having a receiving space for receiving an electrode assembly, a terrace portion formed along a periphery of the receiving portion, and one or more gas discharge portions, wherein each of the gas discharge portions includes: a through hole formed at one or more positions among the cup portion and the terrace portion; a gas-permeable film covering the through hole on the inside of the battery case; and a polymer-based protective film covering the through hole on the outside of the battery case.

[0019] [2] In the above [1], the polymer protective film may include at least one selected from the group consisting of polypropylene, polyethylene, polytetrafluoroethylene, fluorinated ethylene propylene copolymer, perfluoroalkoxy-substituted polytetrafluoroethylene, and ethylene tetrafluoroethylene copolymer.

[0020] [3] In the above [1] and / or [2], the polymer-based protective film may have a case adhesive portion that comes into contact with the battery case at the periphery of the through hole, and the polymer-based protective film may be a portion of the polymer-based protective film that is inserted into the battery case at the case adhesive portion.

[0021] [4] In the above [1] and / or [2], the polymer-based protective film may be provided with a film adhesive portion in contact with the gas-permeable film within the through hole.

[0022] [5] In the above [4], the polymer protective film may have an area greater than the area of ​​the through hole, and the sealing area may have an area less than the area of ​​the through hole.

[0023] [6] In at least one of the above [1] to [5], the polymer-based protective film may include a water-repellent coating layer on a surface exposed to the outside of the battery case.

[0024] [7] In at least one of the above [1] to [6], the polymer-based protective film may contain a ceramic filler therein.

[0025] [8] In the above [7], the ceramic filler may include at least one selected from the group consisting of CaCO3, Ca(OH)2, CaCl2, CaO, KOH, NaOH, and Na2CO3.

[0026] [9] In at least one of the above [1] to [8], the gas-permeable film may include an adhesive resin layer arranged to be in contact with the battery case at the periphery of the through hole, and a permeable resin layer arranged on the adhesive resin layer.

[0027]

[0010] In the above [9], the adhesive resin layer may include a non-fluorinated polyolefin resin.

[0028]

[0011] In the above [9] and / or

[0010] , the permeable resin layer may include a fluorinated polyolefin resin.

[0029]

[0012] In at least one of the above [1] to

[0011] , the gas discharge portion may be formed at one or more locations selected from among a terrace portion and a cup portion adjacent to the terrace portion and not in contact with the electrode assembly inside.

[0030]

[0013] In at least one of the above [1] to

[0012] , the gas discharge unit may be arranged so that the adhesive resin layer is in contact with the pouch-shaped battery case.

[0031]

[0032]

[0014] According to another embodiment of the present invention, a pouch-type secondary battery is provided, which comprises: an electrode assembly; a pouch-type battery case as described above; an electrode lead connected to the electrode assembly and protruding to the outside of the pouch-type battery case via the terrace portion; and a lead film disposed between the electrode lead and the pouch-type battery case on the terrace portion; wherein a portion of the terrace portion is sealed along the periphery of the cup portion to form a sealing portion.

[0033]

[0034]

[0015] According to another embodiment of the present invention, a battery box is provided, including a plurality of pouch-type secondary batteries according to claim 14; and a packaging for accommodating the pouch-type secondary batteries.

[0035]

[0036] The pouch-type battery case according to the present invention is designed to have a gas discharge portion that is provided with a through hole connecting the inside and outside of the case forming a gas discharge portion, a gas-permeable film covering the through hole from the inside, and a polymer-based protective film covering the through hole from the outside, thereby enabling a pouch-type battery case to be implemented that has a gas discharge portion with excellent moisture-blocking performance while maintaining gas discharge at an appropriate level or higher.

[0037] In addition, the pouch-type secondary battery according to the present invention can contribute to improving the lifespan by providing excellent safety and improving durability by applying the pouch-type battery case.

[0038]

[0039] The drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the contents of the invention described above, serve to further understand the technical idea of ​​the present invention. Therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0040] Figure 1 is an exploded assembly diagram of a pouch-type secondary battery.

[0041] Figure 2 is a plan view of a pouch-type secondary battery according to one embodiment of the present invention.

[0042] Figure 3 is a cross-sectional view of a portion of a pouch-type secondary battery having a gas discharge unit according to one embodiment of the present invention.

[0043] Figure 4 is an enlarged cross-sectional view of a portion of a pouch-type secondary battery having a gas discharge unit according to one embodiment of the present invention.

[0044] Figure 5 is an enlarged cross-sectional view of a portion of a pouch-type secondary battery having a gas discharge unit according to one embodiment of the present invention.

[0045] Figure 6 is an enlarged cross-sectional view of a portion of a pouch-type secondary battery having a gas discharge unit according to one embodiment of the present invention.

[0046]

[0047] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided only to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Like reference numerals designate like elements throughout the specification.

[0048] Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used in their common sense to those of ordinary skill in the art to which the present invention pertains. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0049] The terminology used herein is for the purpose of describing embodiments and is not intended to limit the present invention. In this specification, singular forms also include plural forms, unless specifically stated otherwise. As used herein, the terms "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components in addition to the components mentioned.

[0050] In this specification, when it is said that a part includes a certain component, this does not mean that other components are excluded, but rather that other components may be included, unless specifically stated otherwise.

[0051] In this specification, the description of “A and / or B” means A, or B, or A and B.

[0052] In this specification, “%” means weight percent unless explicitly indicated otherwise.

[0053]

[0054] The pouch-type battery case, pouch-type secondary battery, and battery box described in this specification include at least one of the technical configurations described below, and may include any combination between technically possible configurations among the technical configurations below.

[0055]

[0056] pouch-type battery case

[0057] A pouch-type battery case according to the present invention comprises a cup portion having a receiving space for receiving an electrode assembly; a terrace portion formed along a periphery of the receiving portion; and one or more gas discharge portions, each of the gas discharge portions including a through hole formed at one or more positions among the cup portion and the terrace portion; a gas-permeable film covering the through hole on the inside of the battery case; and a polymer-based protective film covering the through hole on the outside of the battery case.

[0058] In general, the gas discharge performance of a gas discharge part is determined by the characteristics of the material constituting the gas discharge part, and depending on the characteristics of the material, the moisture penetration prevention performance and electrolyte leakage prevention performance can be determined, and gas permeability is also a property that varies depending on the material, and the material constituting the gas discharge part plays an important role.

[0059] However, when forming a through hole in the case, even if the liquid permeability of the gas-permeable film covering it is controlled, there is a limit to preventing moisture infiltration from the outside, and when the through hole is filled with another material to prevent moisture infiltration, the problem of a significant decrease in gas discharge performance may occur.

[0060] Accordingly, regardless of the dimensional design or material design of the gas-permeable film applied to the gas discharge portion, a design is to be applied to cover the through-hole on the outside of the pouch-type battery case using a polymer-based protective film so as to prevent moisture infiltration without affecting the gas permeation performance.

[0061]

[0062] FIG. 1 is an exploded assembly diagram of a pouch-type secondary battery (100) according to the present invention, FIG. 2 is a plan view of the pouch-type secondary battery (100), FIG. 3 is a cross-sectional view of a portion of a pouch-type battery case of the pouch-type secondary battery in which a gas exhaust port is provided, and FIGS. 4 to 6 are enlarged cross-sectional views of a portion of a pouch-type battery case of the pouch-type secondary battery in which a gas exhaust port is provided. In FIG. 2, some of the components of the pouch-type secondary battery (100) are omitted for convenience of understanding. As illustrated in FIGS. 1 to 6, the pouch-type secondary battery (100) of the present invention includes a pouch-type battery case (110) including a gas exhaust port (200) according to the present invention, an electrode assembly (160), an electrode lead (180), and a lead film (190).

[0063]

[0064] Referring to the drawings 1 to 6 above, the pouch-type battery case (110) and pouch-type secondary battery (100) of the present invention will be described.

[0065]

[0066] According to one embodiment of the present invention, the pouch-type battery case (110) includes a cup portion (122, 132) having a receiving space for receiving an electrode assembly; a terrace portion (150) formed along a periphery of the receiving portion; and one or more gas discharge portions (200), wherein each gas discharge portion (200) includes a through hole (220) formed at one or more positions among the cup portion and the terrace portion; a gas-permeable film (210) covering the through hole (220) on the inside of the battery case (110); and a polymer-based protective film (230) covering the through hole on the outside of the battery case (110).

[0067]

[0068] (1) Pouch film laminate

[0069] The above pouch-shaped battery case (110) can accommodate an electrode assembly (160) in an inner receiving space. The pouch-shaped battery case (110) can be manufactured by molding a pouch film laminate. In this case, the pouch-shaped battery case (110) can include a substrate layer (not shown), a gas barrier layer (not shown), and a sealant layer (not shown). The substrate layer, the gas barrier layer, and the sealant layer can be sequentially laminated from the outside of the battery case toward the inside.

[0070] The substrate layer is formed on the outermost layer of the pouch film laminate to protect the secondary battery from friction and collision with the outside world. The substrate layer is made of polymer and can electrically insulate the electrode assembly from the outside world.

[0071] The substrate layer may be made of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber. Preferably, the substrate layer may be made of polyethylene terephthalate (PET), nylon, or a combination thereof, which have wear resistance and heat resistance.

[0072] The substrate layer may have a single-layer structure composed of a single material. Alternatively, the substrate layer may have a composite-layer structure composed of two or more materials, each formed as a layer.

[0073] The thickness of the substrate layer may be 5 ㎛ to 50 ㎛, specifically 7 ㎛ to 40 ㎛, and more specifically 25 ㎛ to 38 ㎛. When the thickness of the substrate layer satisfies the above range, the external insulation is excellent, and the thickness of the entire pouch is not thick, so the energy density per volume of the secondary battery can be excellent.

[0074] The gas barrier layer is laminated between the substrate layer and the sealant layer to secure the mechanical strength of the pouch, block the ingress of gas or moisture from outside the secondary battery, and prevent electrolyte leakage from inside the pouch-type battery case.

[0075] The gas barrier layer may be formed of a metal, and specifically, may be formed of an aluminum alloy thin film. When the gas barrier layer is formed using an aluminum alloy thin film, a mechanical strength higher than a predetermined level can be secured, while being light in weight and ensuring complementary electrochemical properties and heat dissipation properties due to the electrode assembly and electrolyte. The aluminum alloy thin film may include at least one selected from the group consisting of metal elements other than aluminum (Al), for example, iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0076] The thickness of the gas barrier layer may be 40 ㎛ to 100 ㎛, specifically 50 ㎛ to 90 ㎛, and more specifically 55 ㎛ to 85 ㎛. When the thickness of the gas barrier layer satisfies the above range, the formability and gas barrier performance are excellent when forming the cup portion.

[0077] The sealant layer is intended to completely seal the interior of the pouch-shaped battery case, which houses the electrode assembly inside, by thermally bonding the sealing portion when the case is sealed. To this end, the sealant layer may be formed of a material having excellent thermal bonding strength.

[0078] The sealant layer may be formed of a material having insulating, corrosion-resistant, and sealing properties. Specifically, since the sealant layer is in direct contact with the electrode assembly and / or the electrolyte inside the pouch-type battery case, it may be formed of a material having insulating and corrosion-resistant properties. In addition, since the sealant layer must completely seal the inside of the pouch-type battery case to prevent material movement between the inside and the outside, it may be formed of a material having high sealing properties (e.g., excellent thermal bonding strength). To secure such insulating, corrosion-resistant, and sealing properties, the sealant layer may be formed of a polymer material.

[0079] The sealant layer may be made of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber, and preferably may be made of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may be composed of cast polypropylene (CPP), acid modified polypropylene (Acid Modified Polypropylene, PPa), polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene terpolymer.

[0080] The thickness of the sealant layer may be 30 ㎛ to 130 ㎛, specifically 50 ㎛ to 120 ㎛, and more specifically 70 ㎛ to 100 ㎛. When the thickness of the sealant layer satisfies the above range, there is an effect of securing the sealing strength of the sealing portion while also securing the formability of the pouch film laminate.

[0081]

[0082] Meanwhile, the pouch film laminate may be drawn and stretched by a punch or the like to manufacture a pouch-shaped battery case (110). As a result, the pouch-shaped battery case (110) may include a cup portion (122) and a receiving portion (124). The receiving portion (124) is a place for receiving the electrode assembly, and may refer to a receiving space formed in the shape of a pocket on the inside of the cup portion (122) as the cup portion (122) is formed.

[0083] According to one embodiment of the present invention, a pouch-type battery case (110) may include a first case (120) and a second case (130) as illustrated in FIG. 1. The first case (120) includes a receiving portion (124) capable of receiving an electrode assembly (160), and the second case (130) may cover the receiving portion (124) from above to prevent the electrode assembly (160) from being separated from the outside of the battery case (110). The first case (120) and the second case (130) may be manufactured such that one side thereof is connected to each other as illustrated in FIG. 1, but are not limited thereto and may be manufactured in various ways, such as being manufactured separately and separated from each other.

[0084] According to another embodiment of the present invention, when forming a cup portion on a pouch film laminate, two symmetrical cup portions (122, 132) can be drawn and formed adjacent to each other on one pouch film laminate. In this case, cup portions (122, 132) can be formed on the first case (120) and the second case (130) respectively, as shown in FIG. 1. After the electrode assembly (160) is accommodated in the receiving portion (124) provided in the cup portion (122) of the first case (120), the bridge portion (140) formed between the two cup portions (122, 132) can be folded so that the two cup portions (122, 132) face each other. In this case, the cup portion (132) of the second case (130) can accommodate the electrode assembly (160) from above. Accordingly, since two cup portions (122, 132) accommodate one electrode assembly (160), an electrode assembly (160) having a thicker thickness can be accommodated than when there is only one cup portion (122). In addition, since one corner of the secondary battery (100) is formed by folding the pouch-type battery case (110), the number of corners to be sealed can be reduced when performing a sealing process later. Accordingly, the process speed of the pouch-type secondary battery (100) can be improved, and the number of sealing processes can be reduced.

[0085] The pouch-type battery case (110) can be sealed while housing the electrode assembly (160) so that a portion of the electrode lead (180) described later, i.e., a terminal portion, is exposed, as shown in FIG. 2. Specifically, when the electrode lead (180) is connected to the electrode tab (170) of the electrode assembly (160) and a lead film (190) is formed on a portion of the electrode lead (180), the electrode assembly (160) can be housed in a receiving portion (124) provided in a cup portion (122) of the first case (120), and the second case (130) can cover the receiving portion (124) from above. Subsequently, as shown in FIG. 2, an electrolyte can be injected into the receiving portion (124), and a portion of the terrace portion (150) formed along the perimeter of the first case (120) and the second case (130) can be sealed to form a sealing portion (151).

[0086] The sealing portion (151) can perform the function of sealing the receiving portion (124). Specifically, the sealing portion can seal the receiving portion (124) by being formed on the terrace portion (150) formed along the perimeter of the receiving portion (124).

[0087] The temperature at which the sealing portion (151) is sealed may be 180°C to 250°C, specifically 200°C to 250°C, and more specifically 211°C to 240°C. When the sealing temperature satisfies the above numerical range, the pouch-type battery case (110) can secure sufficient sealing strength through thermal bonding.

[0088]

[0089] (2) Gas discharge section

[0090] According to one embodiment of the present invention, at least one gas discharge portion (200) of the pouch-shaped battery case (110) includes a through hole formed at at least one position among the cup portion and the terrace portion, a gas-permeable film covering the through hole on the inside of the battery case, and a polymer-based protective film covering the through hole on the outside of the battery case.

[0091] The gas discharge unit (200) above has a better gas discharge performance as the area of ​​the through hole increases. However, increasing the area of ​​the through hole (220) for gas discharge performance has a negative effect on the moisture penetration prevention performance, and even if the dimensional design and materials are controlled to maximize performance, there are clear limitations. Accordingly, the present invention is characterized by providing a gas discharge unit additionally equipped with a polymer protective film that covers the through hole from the outside of the battery case.

[0092]

[0093] Hereinafter, the gas discharge unit (200) of the present invention will be described in more detail with reference to FIGS. 2 to 4. FIG. 2 is an example of a plan view of a pouch-type secondary battery showing the location where the gas discharge unit (200) is formed, FIG. 3 is a cross-sectional view of the pouch-type secondary battery at the portion where the gas discharge unit (200) is formed, and FIGS. 4 to 6 are enlarged cross-sectional views of the gas discharge unit (200) portion of FIG. 3.

[0094] According to one embodiment of the present invention, the gas discharge portion (200) may be formed at one or more locations selected from the terrace portion (150) and the cup portion (122, 132) adjacent to the terrace portion (150) and not in contact with the electrode assembly inside. Here, the cup portion (122, 132) and the receiving portion (124) may not be substantially structurally distinguished, and the recessed portion formed by being molded in the pouch-type battery case (110) may be named the cup portion (122, 132), and the receiving space formed by being recessed in this way may be named the receiving portion (124).

[0095] Referring to FIGS. 2 and 3, the gas discharge portion (200) may be formed in the terrace portion (150) instead of the sealing portion (151), and may be formed in the cup portion (122) or the receiving portion (124) adjacent to the terrace portion (150). In particular, the electrode assembly (160) is accommodated and sealed inside the pouch-type battery case (110) to form the sealing portion (151), and it may be preferable to form the cup portion (122) in a space where the electrode assembly (160) and the pouch-type battery case (110) do not directly contact each other, that is, in a space where the electrode tab (170) is withdrawn from the electrode assembly (160) for electrical connection to the outside and comes into contact with the electrode lead (180).

[0096] At this time, the gas discharge unit (200) may be formed in one unit, or may be provided in two or more units, and the number of gas discharge units (200) may be designed in consideration of the characteristics of the cell applied inside, for example, whether the amount of gas generated is large or relatively small, and if each gas discharge unit (200) is provided with a polymer-based protective film (230) as described above, the moisture blocking performance may be excellent, and therefore, there is no particular limitation on the number.

[0097] As illustrated in FIG. 3, the gas discharge unit (200) may be formed by bonding a gas-permeable film (210) inside the pouch-type battery case (110) (dotted box) to close the through-hole (220), and by bonding a polymer-based protective film (230) outside the pouch-type battery case (110) (solid box) to secondarily close the through-hole (220). In this case, the portion where the gas-permeable film (210) and the pouch-type battery case (110) come into contact may be sealed by a method such as heat sealing, point-to-point bonding using a point-to-point adhesive, or point-to-point bonding using a point-to-point adhesive film.

[0098]

[0099] Referring to FIG. 4, the gas discharge portion (200) illustrated in FIG. 3 can be seen enlarged, and the adhesive resin layer (211) of the gas permeable film (210) may be positioned so as to be in contact with the sealant layer of the pouch-shaped battery case (110).

[0100] In addition, according to one embodiment of the present invention, the polymer-based protective film (230) may be provided with a case adhesive portion (231) that comes into contact with the base T1 layer of the pouch-type battery case (110) at the periphery of the through hole (220), and at this time, the case adhesive portion (231) may be a portion of the polymer-based protective film (230) that is introduced into the inside of the battery case (110). In this case, the introduced case adhesive portion (231) may be integrated with the pouch-type battery case (110) and function as a single resin layer, thereby being effective in blocking moisture from the outside.

[0101]

[0102] Meanwhile, referring to FIG. 5, the gas discharge unit (200) according to one embodiment of the present invention can form a film adhesive portion (232) in an area where the gas permeable film (210) and the polymer protective film (230) come into contact, unlike in FIG. 4. That is, the polymer protective film (230) covers the through hole (220) from the outside of the battery case (110), and the polymer protective film (230) in the through hole (220) can be designed to be introduced into the through hole and come into contact with the gas permeable film (210) covering the through hole (220) from the inside. At this time, the gas discharge unit (200) can be formed by sealing (thermal sealing, point / adhesion, etc.) part or all of the areas where the polymer protective film (230) and the gas permeable film (210) come into contact. In this case, the gas emission performance can be controlled depending on the area of ​​the film adhesive portion (232), and moisture penetration can also be prevented due to the polymer protective film (230) of the remaining portion protruding from the film adhesive portion (232) to the outside of the through hole (220).

[0103] In addition, referring to FIG. 6, the gas discharge unit (200) according to one embodiment of the present invention may be provided with a polymer-based protective film (230) designed to precisely fit the dimensions of the through hole (220), and the film adhesive portion (232) may be formed in an area in contact with the gas-permeable film (210), but a smaller area may be sealed compared to when the polymer-based protective film (230) is larger than the area of ​​the through hole (220).

[0104] In this case, the area to be sealed, i.e., the area of ​​the film adhesive portion (232), can be appropriately controlled, and the gas discharge portion (200) can be designed in consideration of the required gas discharge performance depending on the battery elements mounted inside, such as the components of the positive electrode, negative electrode, or electrolyte, or depending on the purpose for which the battery is used.

[0105] Accordingly, according to one embodiment of the present invention, the polymer-based protective film (230) may have an area greater than or equal to the area of ​​the through hole (220), and the film adhesive portion (232) may have an area less than or equal to the area of ​​the through hole (220). Preferably, the area of ​​the polymer-based protective film (230) may be 100% to 200% of the area of ​​the through hole (220), and the area of ​​the film adhesive portion (232) may be 50% to 100% of the area of ​​the through hole (220), more preferably 50% to 90%, or 50% to 85%, and most preferably 50% to 80%.

[0106]

[0107] In the case where the gas discharge portion (200) having a through hole (220) formed therein to prevent moisture infiltration as illustrated in FIGS. 3 to 6 is covered inside and outside the battery case, the moisture infiltration performance can be improved without deterioration of the gas discharge performance, and the material can be designed to perform not only the function of the polymer-based protective film (230) but also the function of the gas-permeable film (210), so that it can be an effective method for reducing the amount of moisture infiltration while minimizing the deterioration of the gas discharge performance. Preferably, forming the polymer-based protective film (230) as illustrated in FIG. 4 can further maximize the effect in preventing moisture infiltration, and in the case of the structure of FIG. 4, since there is a space that functions as a gas pocket between the gas-permeable film (210) and the polymer-based protective film (230), the deterioration of the gas discharge performance can be minimized compared to the case where the polymer-based protective film (230) is not applied. When bonding is performed in a pouch-type battery case (110) as in the structure of Fig. 4, a sealing effect by heat fusion or sealing by adhesive or a similar effect can be expected.

[0108]

[0109] According to one embodiment of the present invention, the polymer protective film (230) may be made of various materials, and when forming an adhesive portion (232) with the gas-permeable film (210) as in FIG. 5 or 6, it may be preferable to apply a material of the same type as the gas-permeable film (210), particularly the adhesive resin layer (211) on the side in contact with the battery case.

[0110] The above polymer protective film (230) may include at least one material selected from the group consisting of, for example, polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, polytetrafluoroethylene, fluorinated ethylene propylene copolymer, perfluoroalkoxy-substituted polytetrafluoroethylene, ethylene tetrafluoroethylene copolymer, and glass fiber, and preferably may include a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE), or a fluororesin such as polytetrafluoroethylene, fluorinated ethylene propylene copolymer, perfluoroalkoxy-substituted polytetrafluoroethylene, ethylene tetrafluoroethylene copolymer, and more preferably, polytetrafluoroethylene, fluorinated ethylene propylene copolymer, perfluoroalkoxy-substituted polytetrafluoroethylene, It may include a fluororesin such as substituted polytetrafluoroethylene, ethylene tetrafluoroethylene copolymer, etc. In this case, the polypropylene may include cast polypropylene (CPP), acid modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene terpolymer.

[0111] The above acid-modified polyolefin may be one in which a carboxyl group is introduced (graft-modified) by reacting an unsaturated carboxylic acid with a polyolefin resin. In this case, the unsaturated carboxylic acid may include the concept of a carboxylic anhydride, and the carboxyl group may include the concept of a carboxylic anhydride group. The unsaturated carboxylic acid to be reacted with the polyolefin resin may include at least one selected from the group consisting of maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitic acid, maleic anhydride, itaconic anhydride, glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornene dicarboxylic anhydride, and tetrahydrophthalic anhydride, but is not limited thereto.

[0112] The above silane-modified polyolefin refers to a polyolefin resin that has been graft-modified with an unsaturated silane compound. The silane-modified polyolefin may have a structure in which an unsaturated silane compound is graft-copolymerized onto a polyolefin resin, which is the main chain. The silane-modified polyolefin resin may include, but is not limited to, one or more selected from the group consisting of a silane-modified polypropylene resin and a silane-modified ethylene-vinyl acetate copolymer.

[0113]

[0114] In addition, although the polymer protective film (230) is not illustrated in FIGS. 4 to 6, it may form a multilayer structure, for example, a sealing layer may be provided in a portion where the bonding portion (231, 232) is formed, and a blocking layer may be provided on the sealing layer, and at least one separate intermediate layer may be included between the sealing layer and the blocking layer. In the case of forming such a multilayer structure, it may be advantageous in that a layer including a heat-sealable resin can be configured when sealing the polymer protective film using heat fusing. For example, when attaching a polyethylene terephthalate film or a polyimide film to a pouch-type battery case using an adhesive film or adhesive, the polymer protective film may be applied as a single layer in addition to the adhesive layer, and when heat fusing is performed, a polymer protective film having a multilayer structure in which a fusible material such as polypropylene or polyethylene is laminated may be applied.

[0115] Furthermore, according to one embodiment of the present invention, the polymer-based protective film may include a water-repellent coating layer on a surface exposed to the outside of the battery case, and may independently include a ceramic filler therein.

[0116] In the case of the above water-repellent coating layer, it can greatly contribute to the performance of blocking moisture from the outside. For example, the water-repellent coating layer can be formed by controlling the contact angle of the surface of the barrier layer exposed to the outside, forming a coating layer on the barrier layer using a hydrophobic material, or applying the barrier layer with a hydrophobic material. The contact angle can be implemented by injecting a filler on the barrier layer to control the unevenness of the surface, or by controlling the roughness of the roller when extruding the barrier layer.

[0117] In addition, in the case of the ceramic filler, when included in a polymer protective film, it has the advantage of being able to absorb moisture that has entered, and in addition, it can perform the function of absorbing byproducts generated by moisture, such as hydrogen fluoride (HF), and can also improve the ability to prevent damage caused by external physical factors by improving the strength of the film. The ceramic filler may be included in one or more layers among the multilayered layers constituting the polymer protective film, and may be injected to control the unevenness of the surface of the barrier layer, and the position of the layer to be injected may not be particularly limited as long as the content is adjusted at a level that does not lower the durability of the film, but it may be preferable to include the ceramic filler in a layer located internally for the effective removal of moisture and byproducts generated by moisture.

[0118] The above ceramic filler may include at least one selected from the group consisting of, for example, CaCO3, Ca(OH)2, CaCl2, CaO, KOH, NaOH and Na2CO3, and preferably, CaCO3.

[0119]

[0120] Meanwhile, according to one embodiment of the present invention as illustrated in FIGS. 4 to 6, the gas discharge unit (200) includes an adhesive resin layer (211) in contact with a pouch-type battery case (110) and a permeable resin layer (212) disposed on the adhesive resin layer (211).

[0121] The adhesive resin layer (211) is in contact with the pouch-type battery case (110) and is used to adhere the gas discharge unit (200) to the pouch-type battery case (110), and may include any material that is easily adhered to the pouch-type battery case (110). Specifically, the adhesive resin layer (211) may include a non-fluorinated polyolefin resin, and preferably, may include a modified polyolefin resin.

[0122] When the above adhesive resin layer (211) includes a modified polyolefin resin, the adhesive strength between the gas discharge unit (200) and the pouch-type battery case (110) is improved, so that even when the pouch-type secondary battery is stored in a high-temperature environment, the gas discharge unit (200) can be prevented from being detached from the pouch-type battery case (110), causing the electrolyte inside the pouch to leak out and moisture to penetrate.

[0123] For example, the adhesive resin layer (211) may include at least one of an acid-modified polyolefin and a silane-modified polyolefin.

[0124] Acid-modified polyolefin refers to a polyolefin resin that has been graft-modified with an acid. For example, the acid-modified polyolefin may be a polyolefin resin in which a carboxyl group is introduced (graft-modified) by reacting an unsaturated carboxylic acid. In this case, the unsaturated carboxylic acid may include the concept of a carboxylic anhydride, and the carboxyl group may include the concept of a carboxylic anhydride group. The unsaturated carboxylic acid reacted with the polyolefin resin may include at least one selected from the group consisting of maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitic acid, maleic anhydride, itaconic anhydride, glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornene dicarboxylic anhydride, and tetrahydrophthalic anhydride, but is not limited thereto. Among these, it is preferable to apply maleic anhydride to improve the adhesive strength between the gas discharge unit (200) and the electrode lead (180). The acid-modified polyolefin may include at least one selected from the group consisting of acid-modified polypropylene (PPa) and acid-modified polyethylene (PEa), but is not limited thereto.

[0125] Silane-modified polyolefin refers to a polyolefin resin that has been graft-modified with an unsaturated silane compound. The silane-modified polyolefin may have a structure in which an unsaturated silane compound is graft-copolymerized onto a polyolefin resin, which is the main chain. The silane-modified polyolefin resin may include, but is not limited to, one or more selected from the group consisting of silane-modified polypropylene resin and silane-modified ethylene-vinyl acetate copolymer.

[0126] The adhesive resin layer (211) may be modified, and the modification treatment may include ion implantation treatment, plasma treatment, radiation treatment, heat treatment, etc., and a treatment that changes the bonding structure of the polymer layer is preferable. These modification treatments may be performed singly by one type, or may be performed in combination of two or more types. The modified adhesive resin layer (211) may include, but is not limited to, plasma-treated polypropylene (PP).

[0127] The thickness of the adhesive resin layer (211) may be 20 µm to 250 µm, specifically 30 µm to 200 µm, and more specifically 30 µm to 150 µm. When the thickness of the adhesive resin layer (211) satisfies the above numerical range, the adhesive resin layer (211) is melted within a set production time (tact time), so that the gas discharge portion (200) and the pouch-type battery case (110) can be easily fused together.

[0128]

[0129] According to one embodiment of the present invention, the permeable resin layer (212) may be a layer in contact with the adhesive resin layer (211) to facilitate gas discharge.

[0130] The above-mentioned permeable resin layer (212) may include a fluorine-based polyolefin resin, and preferably, may include at least one of polytetrafluoroethylene (PTFE) and polyimide (PI).

[0131] The thickness of the above-mentioned permeable resin layer (212) may be 30 ㎛ to 200 ㎛, specifically 40 ㎛ to 150 ㎛, and more specifically 45 ㎛ to 100 ㎛. When the thickness of the permeable resin layer (212) satisfies the above numerical range, the gas discharge function can be smoothly performed without detachment of the gas discharge part (200) due to venting even when the internal pressure of the pouch-type battery case (110) increases.

[0132]

[0133] Meanwhile, according to one embodiment of the present invention, the thickness (T) of the gas permeable film (210) F ) may be 80 ㎛ to 500 ㎛, specifically 80 ㎛ to 450 ㎛, 80 ㎛ to 400 ㎛, 90 ㎛ to 350 ㎛, and more preferably 100 ㎛ to 300 ㎛. When the above range is satisfied, it is easy to control the thickness ratio of the adhesive resin layer (211) and the permeable resin layer (212) constituting the gas permeable film (210), and design considering adhesive force and gas discharge performance can be facilitated.

[0134] The thickness (T) of the above permeable resin layer (212) T ) thickness (T) of the adhesive resin layer (211) A ) ratio (T A / T T ) may 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. The ratio (T A / T T) satisfies the above numerical range, it may be easy to implement a gas discharge unit (200) that can discharge gas while maintaining adhesiveness without permanent damage to the gas discharge unit (200) due to venting while minimizing the pressure at which the gas discharge unit (200) starts to operate, and it may also be desirable to satisfy the above range when designing a moisture blocking index.

[0135]

[0136] Accordingly, the pouch-type battery case according to one embodiment of the present invention can significantly improve the performance of preventing electrolyte leakage and moisture infiltration by having the gas discharge portion as described above, while maintaining a satisfactory level of gas discharge performance. As a result, there is no problem of corrosion due to generated gas or corrosion due to moisture infiltration or electrolyte leakage, thereby contributing to an increase in durability and an improvement in lifespan. In addition, the operating performance of the cell can be maintained through continuous gas discharge, and the risk of explosion due to swelling is also reduced, thereby ensuring safety.

[0137]

[0138] pouch-type secondary battery

[0139] According to another embodiment of the present invention, a pouch-type secondary battery (100) is provided, which includes: 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 the terrace portion (150); and a lead film (190) disposed between the electrode lead (180) and the pouch-type case (110) on the terrace portion (150), wherein a portion of the terrace portion (150) is sealed along the periphery of the cup portion (122, 132) to form a sealing portion (151).

[0140]

[0141] Since the pouch-type battery case (110) and the gas discharge unit (200) provided in the pouch-type battery case (110) overlap with the above-described content, the description thereof will be omitted, and below, the components included in the other pouch-type secondary battery (100) will be described.

[0142]

[0143] (1) Electrode assembly

[0144] According to one embodiment of the present invention, the electrode assembly (160) may be housed in the receiving portion (124) of the pouch-type battery case (110) and sealed by a sealing portion (151) formed by thermal fusion of the terrace portion (150) after electrolyte injection.

[0145] The electrode assembly (160) may be formed by sequentially stacking an anode, a separator, and a cathode. Specifically, the electrode assembly (160) may include two types of electrodes, an anode and a cathode, and a separator interposed between the electrodes to mutually insulate the electrodes.

[0146] The positive and negative electrodes may each have a structure in which an active material slurry is applied to an electrode current collector in the form of a metal foil or metal mesh containing aluminum and copper, respectively. The slurry is typically formed by stirring granular active materials, auxiliary conductors, binders, and conductive agents with the addition of a solvent. The solvent can be removed in a subsequent process.

[0147] A slurry containing an electrode active material, a binder, and / or a conductive material is applied to a positive electrode current collector and a negative electrode current collector to manufacture a positive electrode and a negative electrode, and these are laminated on both sides of a separator, thereby manufacturing an electrode assembly (160) in a predetermined shape. The types of electrode assembly (160) may include, but are not limited to, a stack type, a jelly roll type, a stack and folding type, etc.

[0148] The electrode assembly (160) may include an electrode tab (170).

[0149] Referring to FIG. 1, the electrode tabs (170) are respectively connected to the positive and negative electrodes of the electrode assembly (160), and protrude outward from the electrode assembly (160) to serve as a path for electrons to move between the inside and the outside of the electrode assembly (160). The electrode current collector included in the electrode assembly (160) may be composed of a portion where an electrode active material is applied and a terminal portion where the electrode active material is not applied, i.e., a non-coated portion. The electrode tabs (170) may be formed by cutting the non-coated portion or by connecting a separate conductive member to the non-coated portion by ultrasonic welding, etc. As illustrated in FIG. 1, the electrode tabs (170) may protrude in different directions of the electrode assembly (160), but are not limited thereto, and may be formed to protrude in various directions, such as protruding in parallel in the same direction from one side.

[0150]

[0151] (2) Electrode leads

[0152] According to one embodiment of the present invention, the electrode lead (180) can supply electricity to the outside of the secondary battery (100). The electrode lead (180) can be connected to the electrode tab (170) of the electrode assembly (160) by spot welding or the like.

[0153] Referring to FIGS. 1 and 3, the electrode lead (180) may be connected to the electrode assembly (160) and may protrude to the outside of the pouch-type battery case (110) via the terrace portion (150). Specifically, one end of the electrode lead (180) may be connected to the electrode assembly (160), particularly to the electrode tab (170), and the other end of the electrode lead (180) may protrude to the outside of the pouch-type battery case (110) via the terrace portion (150).

[0154] The electrode lead (180) may include a positive lead (182) having one end connected to the positive tab (172) and extending in the direction in which the positive tab (172) protrudes, and a negative lead (184) having one end connected to the negative tab (174) and extending in the direction in which the negative tab (174) protrudes. Both the positive lead (182) and the negative lead (184) may have other ends protruding outward from the battery case (110). Accordingly, electricity generated inside the electrode assembly (160) may be supplied to the outside. In addition, since the positive tab (172) and the negative tab (174) are formed to protrude in various directions, the positive lead (182) and the negative lead (184) may also extend in various directions, respectively. The positive lead (182) and the negative lead (184) may be made of different materials. That is, the positive electrode lead (182) may be made of the same aluminum (Al) material as the positive electrode collector, and the negative electrode lead (184) may be made of the same copper (Cu) material as the negative electrode collector or a nickel (Ni)-coated copper material. A portion of the electrode lead (180) protruding outside the battery case (110) may serve as a terminal portion and be electrically connected to an external terminal.

[0155] One surface of the electrode lead (180) that is in direct contact with the lead film (190) and / or the gas discharge portion (200) may be coated with at least one selected from the group consisting of chromium (Cr), nickel (Ni), aluminum oxide (Al2O3), zirconium (Zr)-based anhydride salts, and titanium (Ti)-based anhydride salts. In this case, corrosion resistance against the electrolyte and adhesion to the lead film (190) and / or the gas discharge portion (200) can be secured.

[0156]

[0157] (3) Lead film

[0158] According to one embodiment of the present invention, the lead film (190) prevents electricity generated from the electrode assembly (160) from flowing to the battery case (110) through the electrode lead (180) and maintains the sealing of the battery case (110). To this end, the lead film (190) may be formed of a non-conductive material that does not conduct electricity well. In general, the lead film (190) is often made of an insulating tape that is easy to attach to the electrode lead (180) and / or the gas exhaust unit (200) and has a relatively thin thickness, but is not limited thereto, and any material capable of insulating the electrode lead (180) may be used.

[0159] The lead film (190) may be positioned to wrap around the outer circumference of the electrode lead (180). The lead film (190) may be positioned limited to the terrace portion (150) where the sealing portion (151) where the first case (120) and the second case (130) of the pouch-type battery case (110) are thermally fused is located, and the electrode lead (180) may be adhered to the battery case (110).

[0160] The lead film (190) may be placed between the electrode lead (180) and the pouch-type battery case (110). For example, as illustrated in FIG. 3, the lower case (110), the lead film (190), the electrode lead (180), the lead film (190), and the upper case (110) may be sequentially stacked in the terrace portion (150) area.

[0161]

[0162] Meanwhile, the lead film (190) may include one or more layers. Specifically, the lead film (190) may include a sequentially laminated metal adhesive layer, a core layer, and a pouch adhesive layer.

[0163] The metal adhesive layer may be in direct contact with the electrode lead (180) and may be used to adhere the lead film (190) to the electrode lead (180). The metal adhesive layer may include any material that is easily adhered to the electrode lead (180). Specifically, the metal adhesive layer may include an acid-modified polyolefin. For example, the metal adhesive layer may include at least one of acid modified polypropylene (PPa), acid modified polyethylene (PEa), and plasma-treated polypropylene (PP), but is not limited thereto. The thickness may be 50 ㎛ to 80 ㎛, specifically 50 ㎛ to 75 ㎛, and more specifically 60 ㎛ to 75 ㎛. When the thickness of the metal adhesive layer satisfies the above numerical range, there is an effect of preventing a through-hole and leakage at the edge portion when the electrode lead and the lead film are fused.

[0164] The core layer may be a layer located at 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 a colorant. Among them, the polymer included in the core layer may be a homopolymer. When the core layer includes a homopolymer, the melting point of the core layer can be controlled within the above numerical range, and deformation due to heat can be minimized, which is advantageous in terms of securing insulation. The thickness of the core layer may be 40 ㎛ to 70 ㎛, specifically 50 ㎛ to 70 ㎛, and more specifically 60 ㎛ to 70 ㎛. When the thickness of the core layer satisfies the above numerical range, deformation due to heat applied during fusion and sealing is prevented, thereby providing a robust design effect in terms of securing insulation.

[0165] The pouch adhesive layer may be a layer that directly contacts the battery case (110), specifically, the sealant layer of the pouch film laminate. The pouch adhesive layer may include, but is not limited to, polypropylene and polyolefin elastomer (POE). Among them, the polymer included in the pouch adhesive layer may be a copolymer. The melting point of the pouch adhesive layer including the copolymer in the pouch adhesive layer can be controlled within the above numerical range, and has a similar melting point to the polymer in the sealant layer of the pouch film laminate, which is advantageous in ensuring sealing processability. The thickness of the pouch adhesive layer may be 40 ㎛ to 100 ㎛, specifically, 40 ㎛ to 80 ㎛, and more specifically, 40 ㎛ to 60 ㎛. When the thickness of the pouch adhesive layer satisfies the above numerical range, there is an effect of ensuring a polymer (e.g., polypropylene) residual rate sufficient to secure strength when sealing between the electrode lead and the pouch film laminate.

[0166]

[0167] (4) Electrolyte

[0168] The pouch-type secondary battery (100) according to the present invention may further include an electrolyte (not shown) that is poured into the pouch-type battery case (110). The electrolyte is for moving lithium ions generated by an electrochemical reaction of an electrode during charging / discharging of the secondary battery (100), and may include a non-aqueous organic electrolyte that is a mixture of a lithium salt and an organic solvent, or a polymer using a polymer electrolyte. Furthermore, the electrolyte may include a solid electrolyte of a sulfide-type, oxide-type, or polymer-type, and such a solid electrolyte may have flexibility that is easily deformed by an external force.

[0169]

[0170] battery box

[0171] According to one embodiment of the present invention, a battery box including the pouch-type secondary battery is provided. The battery box according to one embodiment of the present invention may include the pouch-type secondary battery and packaging that accommodates the pouch-type secondary battery. The pouch-type secondary battery may be configured to charge and discharge electric energy, and in this case, the pouch-type secondary battery may be a secondary battery according to the embodiment of the present invention described above.

[0172] To increase the electric capacity or voltage of the above battery box, the pouch-type secondary batteries may be configured in multiple units. The multiple pouch-type secondary batteries may be arranged in a predetermined manner, for example, they may be stacked in one direction, but the arrangement of the pouch-type secondary batteries is not particularly limited.

[0173] The above packaging may be configured to accommodate a secondary battery and protect it from external contamination or impact. For example, the packaging may have a body shape, but the structure or shape of the packaging is not particularly limited as long as it can accommodate a secondary battery.

[0174] Additionally, the packaging may be equipped with components that perform specific functions to ensure the operation or safety of the battery box according to one embodiment of the present invention. For example, the packaging may be equipped with a connector or bus bar for energizing the secondary battery with the outside, or a vent plug for connecting the inside and outside of the packaging.

[0175] The above battery box may be used to mean, for example, a battery module or a battery pack, and may encompass a packaging and an assembly of battery cells containing a plurality of secondary batteries within the packaging.

[0176]

[0177] Hereinafter, the present invention will be described in more detail through specific examples. However, the following examples are merely illustrative and serve to aid understanding of the present invention and do not limit its scope. It will be apparent to those skilled in the art that various modifications and variations are possible within the scope and technical spirit of this disclosure, and such modifications and variations are naturally within the scope of the appended claims.

[0178]

[0179] Examples and Comparative Examples

[0180] Example 1

[0181] (1) Manufacturing of pouch-type battery case

[0182] A pouch film laminate having a polyethylene terephthalate (PET) film measuring 266 mm in width, 50 m in height, and 12 ㎛ in thickness and a nylon film measuring 266 mm in width, 50 m in height, and 25 ㎛ in thickness were laminated on one side of an aluminum alloy film measuring 266 mm in width, 50 m in height, and 60 ㎛ in thickness, and a polypropylene film measuring 266 mm in width, 50 m in height, and 80 ㎛ in thickness was laminated on the other side, thereby manufacturing a pouch film laminate having a polyethylene terephthalate / nylon / aluminum alloy film / polypropylene film structure. Here, the polyethylene terephthalate film and the nylon film are substrate layers, the aluminum alloy film is a gas barrier layer, and the polypropylene film is a sealant layer.

[0183] The above pouch film laminate was formed to manufacture a pouch-shaped battery case including a receiving portion and a terrace portion, and a through hole was formed on the receiving portion (cup portion) adjacent to the terrace portion as shown in FIG. 3, a gas-permeable film was thermally bonded on the inside of the pouch-shaped battery case, and a polymer protective film was thermally bonded on the outside of the pouch-shaped battery case to form a gas discharge portion having a structure as shown in FIG. 3.

[0184] At this time, the gas-permeable film was applied as a film in which 100 ㎛ of acid-modified polypropylene (PPa) was laminated as an adhesive resin layer and 100 ㎛ of polytetrafluoropropylene (PTFE) was laminated as a permeable resin layer, and a polytetrafluoroethylene tape having a thickness of 80 ㎛ was applied as a polymer-based protective film.

[0185]

[0186] (2) Manufacturing of pouch-type secondary batteries

[0187] An electrode assembly was manufactured by stacking and laminating the cathode, anode, and porous polyethylene separator. Thereafter, an electrode lead was attached to the electrode assembly.

[0188] An electrolyte was prepared by dissolving LiPF6 in a solvent (EC:EMC:DMC = 3:3:4 volume ratio) to a concentration of 1.0 M. The electrode assembly was placed in the pouch-type battery case with the tip of the electrode lead extended outward, and the electrolyte was poured.

[0189] Next, a 200 μm thick lead film was laminated on the lower surface of the electrode lead and the upper surface of the gas discharge portion, respectively. The lead film includes a 75 μm thick metal adhesive layer containing copolymer polypropylene and acid-modified polypropylene, a 65 μm thick core layer containing homopolymer polypropylene, and a 60 μm thick pouch adhesive layer containing copolymer polypropylene.

[0190] Afterwards, the sealing part of the pouch-type battery case was sealed for 2 seconds under the conditions of a seal bar area of ​​200 mm × 10 mm, 212°C, and 0.27 MPa, and then left at 60°C for 4 hours to manufacture a pouch-type secondary battery.

[0191]

[0192] Example 2

[0193] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a non-stretched polypropylene (cPP) tape (acrylic polymer adhesive) with a thickness of 80 ㎛ was used as a polymer protective film to form a gas discharge portion, and sealing was applied using an adhesive rather than heat-sealing.

[0194]

[0195] Example 3

[0196] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a non-stretched polypropylene (cPP) tape (natural rubber (isoprene) adhesive) with a thickness of 80 ㎛ was used as a polymer-based protective film to form a gas discharge portion, and sealing was applied using an adhesive rather than heat-sealing.

[0197]

[0198] Comparative Example 1

[0199] A pouch-type secondary battery was manufactured in the same manner as Example 1, except that a polymer-based protective film was not applied to form a gas discharge portion.

[0200]

[0201] Comparative Example 2

[0202] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a 1,013 ㎛ thick acrylic double-sided tape (3M, 4910 VHB) was used as a polymer protective film to form a gas discharge portion, and sealing was applied using an adhesive rather than heat sealing.

[0203]

[0204] Comparative Example 3

[0205] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a 50 ㎛ thick aluminum foil (acrylic polymer adhesive) was used as a polymer protective film to form a gas discharge portion, and sealing was applied using an adhesive rather than heat-sealing.

[0206]

[0207] Experimental Example 1: Evaluation of the Gas Emission Section

[0208] The properties of the gas permeable film were measured and the performance was evaluated using the following method for the following items.

[0209] 1) Confirmation of gas emission rate (cc / day) and desorption: Using pressure equipment from ITS, CO2 was injected into the pouch-type secondary battery to increase the pressure inside the pouch to 1.5 atm or 2.0 atm, and the amount of gas emitted was measured for 24 hours at 60℃, and it was confirmed whether the polymer protective film was desorbed due to deformation of the case caused by the increase in pressure inside the pouch. The results are shown in Table 1 below.

[0210] 2) HF concentration (ppm): After leaving the pouch-type secondary battery under conditions of 60℃ and 90% relative humidity for a week, the secondary battery was opened, 20 g of electrolyte was collected, and the HF concentration (weight ppm) was measured to evaluate the degree of moisture penetration, and the results are shown in Table 1 below.

[0211] 3) Tensile strength (N / 15mm): After cutting the polymer protective film to 15 mm (MD) x 10 mm (TD), the polymer protective film was fastened to the upper and lower jigs using UTM equipment (ZwickRoell) in accordance with ASTM 638, and the gap distance was set to 30 mm. When pulling at a speed of 5 mm / min, the maximum value of the force (N) applied until no breakage occurred was indicated. In general, the unit of tensile strength is N / mm 2 However, the maximum force until the breakage of a 15 mm long sample is measured without considering the thickness of each film, and the unit is expressed as N / 15 mm.

[0212] Discharge rate (@1.5 atm, cc / day)Discharge rate (@2.0 atm, cc / day)HF concentration (ppm, wt)Tensile strength (N / 15mm)DetachmentExample 12.66.1619.414.7XExample 2-5.3905.77.7XExample 3-4.8917.58.1XComparative example 13.2-1010.0-XComparative example 2-6.9857.50.6XComparative example 3-6.3865.263.8O

[0213] According to Table 1 above, in the case of Example 1, the gas emission rate does not differ significantly from that of Comparative Example 1 in which the polymer-based protective film was not applied, but it can be confirmed that the HF concentration increases significantly compared to the Examples in which the polymer-based protective film was not applied. For reference, in the case of the gas emission rate, the emission amount was measured in cc units for 24 hours, so the difference between the Examples and the Comparative Examples cannot be considered large. However, the HF concentration is an important factor that must be controlled because it can rapidly deteriorate the battery performance itself if it increases beyond a certain content.

[0214] In addition, compared to the above examples, the film of Comparative Example 2, i.e., the double-sided tape, has a thick thickness and thus performs the function of preventing moisture penetration to a certain extent, and its gas discharge performance is also satisfactory, but its tensile strength is weak, so it can be considered impossible for commercialization. In addition, in the case of using the aluminum foil of Comparative Example 3, although the tensile strength is strong, it was confirmed that there was a problem of detachment due to the insufficient flexibility of the material itself, which could not respond to deformation such as swelling of the pouch-type battery case.

[0215] On the other hand, it can be confirmed that Examples 1 to 3 using a polymer-based protective film can maintain gas emission performance to the maximum extent possible, prevent moisture penetration, maintain tensile strength above a certain level, and respond to deformation of the pouch-type battery case through the flexibility of the material itself.

[0216]

[0217] [Explanation of symbols]

[0218] 100: Pouch-type secondary battery

[0219] 110: Pouch-type battery case

[0220] 120: Case 1

[0221] 122: Cup

[0222] 124: Reception area

[0223] 130: Case 2

[0224] 132: Cup

[0225] 140: Bridge section

[0226] 150: Terrace

[0227] 151: Sealing part

[0228] 160: Electrode assembly

[0229] 170: Electrode tab

[0230] 172: Positive tab

[0231] 174: Negative tab

[0232] 180: Electrode lead

[0233] 182: Positive lead

[0234] 184: Negative lead

[0235] 190: Lead Film

[0236] 200: Gas exhaust

[0237] 210: Gas permeable film

[0238] 211: Adhesive resin layer

[0239] 212: Permeable resin layer

[0240] 220: Through hole

[0241] 230: Polymer protective film

[0242] 231: Case adhesive

[0243] 232: Film adhesive

Claims

1. A pouch-shaped battery case including a cup portion having a receiving space for storing an electrode assembly, a terrace portion formed along the periphery of the receiving portion, and one or more gas discharge portions. Each of the above gas discharge portions, A through hole formed at one or more locations among the cup portion and terrace portion; A gas-permeable film covering the through hole on the inside of the battery case; and A pouch-type battery case, comprising a polymer-based protective film covering the through hole on the outside of the battery case.

2. In paragraph 1, A pouch-type battery case, wherein the polymer-based protective film comprises at least one selected from the group consisting of polypropylene, polyethylene, polytetrafluoroethylene, fluorinated ethylene propylene copolymer, perfluoroalkoxy-substituted polytetrafluoroethylene, and ethylene tetrafluoroethylene copolymer.

3. In paragraph 1, The above polymer protective film is provided with a case adhesive portion that comes into contact with the battery case at the periphery of the through hole, The above polymer protective film is a pouch-type battery case in which a portion of the polymer protective film is introduced into the inside of the battery case from the case adhesive portion.

4. In paragraph 1, A pouch-type battery case in which the polymer-based protective film is provided with a film adhesive portion in contact with a gas-permeable film within the through hole.

5. In paragraph 4, A pouch-type battery case, wherein the polymer-based protective film has an area greater than the area of ​​the through hole, and the film adhesive portion has an area less than the area of ​​the through hole.

6. In paragraph 1, A pouch-type battery case, wherein the polymer-based protective film includes a water-repellent coating layer on a surface exposed to the outside of the battery case.

7. In paragraph 1, The above polymer protective film is a pouch-type battery case containing a ceramic filler inside.

8. In paragraph 7, A pouch-shaped battery case, wherein the ceramic filler comprises at least one selected from the group consisting of CaCO3, Ca(OH)2, CaCl2, CaO, KOH, NaOH, and Na2CO3.

9. In paragraph 1, A pouch-shaped battery case, wherein the gas-permeable film comprises an adhesive resin layer arranged to be in contact with the battery case at the periphery of the through hole and a permeable resin layer arranged on the adhesive resin layer.

10. In paragraph 9, A pouch-shaped battery case, wherein the adhesive resin layer comprises a non-fluorinated polyolefin resin.

11. In paragraph 9, A pouch-shaped battery case, wherein the above-mentioned permeable resin layer comprises a fluorinated polyolefin resin.

12. In paragraph 1, A pouch-shaped battery case, wherein the gas discharge portion is formed at one or more locations selected from among a terrace portion and a cup portion adjacent to the terrace portion and not in contact with the electrode assembly inside.

13. In paragraph 1, A pouch-shaped battery case, wherein the gas discharge portion is positioned so that the adhesive resin layer is in contact with the pouch-shaped battery case.

14. An electrode assembly; a pouch-shaped battery case according to claim 1; an electrode lead connected to the electrode assembly and protruding to the outside of the pouch-shaped battery case via the terrace portion; and a lead film disposed between the electrode lead and the pouch-shaped battery case on the terrace portion; A pouch-type secondary battery in which a portion of the above terrace portion is sealed along the periphery of the cup portion to form a sealing portion.

15. A plurality of pouch-type secondary batteries according to Article 14; and A battery box including a packaging that accommodates the above pouch-type secondary battery.

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