Pouch-type secondary battery and battery pack including same

Abstract

A pouch-type secondary battery according to the present invention includes an electrode assembly: an outer material including an accommodation unit for accommodating the electrode assembly and a terrace unit formed along the circumference of the accommodation unit and having a sealing unit in which a part of the width is sealed; an electrode lead which is electrically connected to the electrode assembly and protrudes to the outside of the outer material; a lead film disposed between the electrode lead and the outer material; a gas induction unit disposed between the electrode lead and the lead film and including a transmission unit provided on the outside of the outer material and at least one gas flow path extending from the transmission unit toward the electrode assembly via the sealing unit; and a reinforcing film disposed on the lead film so as to cover at least a portion of the transmission unit.

Description

Pouch-type secondary battery and battery pack including the same The present invention relates to a pouch-type secondary battery and a battery pack including the same, and more particularly, to a pouch-type secondary battery and a battery pack including a gas induction unit. 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. 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. Pouch-type secondary batteries can generate gas within the pouch during high-temperature operation, overcharging, or short-circuiting. If gas pressure within the pouch increases, the pouch can vent, potentially leading to an explosion or fire. Accordingly, research is being conducted on various types of gas exhaust components to solve the above problems, and the need for gas exhaust components that simultaneously consider gas exhaust, moisture infiltration from the outside, and electrolyte leakage, gas exhaust components that can withstand high internal pressure but have low operating pressure, and gas exhaust components with excellent durability is continuously increasing. The present invention is intended to solve the above problems, and to provide a pouch-type secondary battery and a battery pack including the same, which improve durability by applying a reinforcing film to prevent deformation of a gas induction portion in a secondary battery equipped with a gas induction portion, thereby solving the problem of moisture infiltration or electrolyte leakage due to stretching of a film in a portion through which gas is transmitted while maintaining a gas discharge rate at an appropriate level. [1] According to one embodiment of the present invention, a pouch-type secondary battery is provided, including: an electrode assembly; an outer shell including a receiving portion for receiving the electrode assembly, and a terrace portion formed along a periphery of the receiving portion, the terrace portion having a sealing portion with a portion of the width sealed; an electrode lead electrically connected to the electrode assembly and protruding to the outside of the outer shell; a lead film disposed between the electrode lead and the outer shell; a gas induction portion disposed between the electrode lead and the lead film, the gas induction portion including a permeation portion provided on the outside of the outer shell and at least one gas path extending from the permeation portion toward the electrode assembly via the sealing portion; and a reinforcing film disposed on the lead film so as to cover at least a portion of the permeation portion. [2] In the above [1], the secondary battery may be configured such that the interface between the lead film and the gas induction part is opened along the gas path due to an increase in the internal pressure of the outer material, thereby providing a gas discharge path. [3] In the above [1] and / or [2], the reinforcing film may include an insertion portion occupying a portion of the width of the sealing portion, and the insertion portion may be a region in which one end of the reinforcing film extends in the direction of the inner side of the outer material and is inserted between the outer material of the sealing portion and the lead film. [4] In at least one of the above [1] to [3], the reinforcing film may have an area based on the outer circumference that is 100% to 500% of the area of ​​the transmission portion. [5] In at least one of the above [1] to [4], the reinforcing film may be disposed on the lead film so as to cover the entire permeable portion of the gas induction portion and a portion of the gas passage. [6] In at least one of the above [1] to [5], the reinforcing film may have a hollow formed therein, and the area of ​​the hollow may be smaller than the area of ​​the transmission portion. [7] In at least one of the above [1] to [6], the reinforcing film may have a hollow portion formed therein, and the area of ​​the hollow portion may be 50% to 90% of the area of ​​the transmission portion. [8] In at least one of the above [1] to [7], the reinforcing film may include at least one selected from the group consisting of a polyester resin, a polyolefin resin, a polyamide resin, and a polycarbonate resin. [9] In at least one of the above [1] to [8], the reinforcing film includes an adhesive layer in contact with the lead film; and a protective layer disposed on the adhesive layer; and the protective layer may include at least one selected from the group consisting of a polyester resin, a polyolefin resin, a polyamide resin, and a polycarbonate resin.

[0010] In at least one of the above [1] to [9], the reinforcing film is hollow and includes an adhesive layer in contact with the lead film; a protective layer disposed on the adhesive layer; and an insulating layer disposed on the protective layer; and the protective layer may include at least one selected from the group consisting of a polyester resin, a polyolefin resin, a polyamide resin, and a polycarbonate resin.

[0011] In at least one of the above [1] to

[0010] , the gas induction unit may have a structure in which an adhesive resin layer and a permeable resin layer are laminated from the upper surface of the electrode lead.

[0012] In the above

[0011] , the adhesive resin layer may have one end protruding toward the outside of the outer material more than one end of the permeable resin layer protruding toward the outside of the outer material.

[0013] In the above

[0011] and / or

[0012] , the lead film may have one end protruding outwardly of the outer material more protruding than one end of the permeable resin layer protruding outwardly of the outer material.

[0014] According to another embodiment of the present invention, a battery pack is provided, comprising: a plurality of pouch-type secondary batteries; and a packaging for accommodating the secondary batteries, wherein the pouch-type secondary batteries include: an electrode assembly; an outer case including a receiving portion for accommodating the electrode assembly, and a terrace portion formed along a periphery of the receiving portion, the terrace portion having a sealing portion with a portion of the width sealed; an electrode lead electrically connected to the electrode assembly and protruding to the outside of the outer case; a lead film disposed between the electrode lead and the outer case; a gas induction portion disposed between the electrode lead and the lead film, the gas induction portion including a permeable portion provided on the outside of the outer case and one or more gas channels extending from the permeable portion toward the electrode assembly via the sealing portion; and a reinforcing film disposed on the lead film so as to cover at least a portion of the permeable portion. The pouch-type secondary battery and battery pack according to the present invention have the advantage of introducing a reinforcing film that covers the permeable portion of the gas induction portion, and introducing it on the upper surface of the lead film, thereby preventing whitening that occurs when the lead film is continuously subjected to tension as gas is discharged, and further solving the problem of electrolyte leakage, while also reducing the possibility of moisture infiltration. In addition, the pouch-type secondary battery and battery pack according to the present invention introduce a reinforcing film covering the permeable portion of the gas induction portion so as to minimize the slowdown in gas discharge speed due to the reinforcing film covering the permeable portion, and by controlling the material of the layer constituting the reinforcing film, the area of ​​the permeable portion covered by the reinforcing film, whether a hollow is formed, and the laminated structure, a gas induction portion having excellent durability can be implemented. Figure 1 is an exploded assembly diagram of a pouch-type secondary battery. Figure 2 is a cross-sectional view of a sealed pouch-type secondary battery. Figure 3 is an example of an enlarged cross-sectional view of part A of box 2, showing the state before the interface between the lead film and the gas induction part is opened. Fig. 4 is an example of an enlarged cross-sectional view of part A of box 2, showing a state in which the interface between the lead film and the gas induction section is open. Figure 5 is another example of an enlarged cross-sectional view of part A of box 2, showing the state before the interface between the lead film and the gas induction film is opened. Figure 6 is another example of an enlarged cross-sectional view of part A of box 2, showing the state before the interface between the lead film and the gas induction film is opened. Figure 7 is a top perspective view of the electrode lead portion where the reinforcing film covers the entire permeable portion of the gas induction portion. Figure 8 is a top perspective view of an electrode lead portion in which a hollow reinforcing film covers a portion of a permeable portion of a gas induction portion. Figure 9 is a top perspective view of an electrode lead portion in which a hollow reinforcing film covers a portion of the permeable portion of a gas induction portion. Figure 10 is an enlarged cross-sectional view of a two-layer structure reinforcing film. Figure 11 is an enlarged cross-sectional view of a three-layer structure reinforcing film. 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. 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. 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. 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. In this specification, the description of “A and / or B” means A, or B, or A and B. In this specification, “%” means weight percent unless explicitly indicated otherwise. The pouch-type secondary battery and battery pack described herein include at least one of the technical configurations described below, and may include any combination between technically possible configurations among the technical configurations below. A pouch-type secondary battery according to the present invention is characterized by including: an electrode assembly; a housing portion for accommodating the electrode assembly; and a terrace portion formed along a periphery of the housing portion and having a sealing portion with a portion of the width sealed; an electrode lead electrically connected to the electrode assembly and protruding to the outside of the housing portion; a lead film disposed between the electrode lead and the housing portion; a gas induction portion disposed between the electrode lead and the lead film, the gas induction portion including a permeation portion provided on the outside of the housing portion and one or more gas channels extending from the permeation portion toward the electrode assembly via the sealing portion; and a reinforcing film disposed on the lead film so as to cover at least a portion of the permeation portion. First, each component of the pouch-type secondary battery of the present invention will be described in more detail with reference to the drawings. FIG. 1 is an exploded assembly diagram of a pouch-type secondary battery (100) according to the present invention, and FIG. 2 is a cross-sectional view of a sealed pouch-type secondary battery (100). In FIG. 2, some of the components of the pouch-type secondary battery (100) are omitted for ease of understanding. As illustrated in FIGS. 1 and 2, the pouch-type secondary battery (100) of the present invention includes an outer material (110), an electrode assembly (160), an electrode lead (180), a lead film (190), a gas induction part (200), and a reinforcing film (300). (1) Exterior material According to one embodiment of the present invention, the outer packaging material (110) can accommodate an electrode assembly (160) inside. The outer packaging material (110) can be manufactured by molding a pouch film laminate. In this case, the pouch film laminate can include a substrate layer, a gas barrier layer, and a sealant layer. In the pouch film laminate, the substrate layer, the gas barrier layer, and the sealant layer can be sequentially laminated. 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. 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. 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. 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. 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 outer material. 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). 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. The sealant layer is intended to completely seal the interior of the outer material by thermally bonding the outer material with the electrode assembly when the outer material is sealed. To this end, the sealant layer may be formed of a material having excellent thermal bonding strength. 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 electrolyte inside the outer 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 outer 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. 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. 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. Meanwhile, the pouch film laminate may be drawn and stretched by a punch or the like to manufacture the outer material (110). As a result, the outer material (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. According to one embodiment of the present invention, the outer 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 outer 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. 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 outer casing (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. The outer material (110) may 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. 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) may be housed in a receiving portion (124) provided in a cup portion (122) of the first case (120), and the second case (130) may cover the receiving portion (124) from above. Subsequently, an electrolyte may 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) may be sealed to form a sealing portion (not shown). The sealing portion can serve to seal 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). The temperature at which the sealing portion is sealed may be 180°C to 250°C, specifically 200°C to 250°C, and more specifically 210°C to 240°C. When the sealing temperature satisfies the above numerical range, the exterior material (110) can secure sufficient sealing strength through thermal bonding. (2) Electrode assembly According to one embodiment of the present invention, the electrode assembly (160) may be inserted into the outer material (110) and sealed by the outer material (110) after electrolyte injection. 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. 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. 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. The electrode assembly (160) may include an electrode tab (170). The electrode tabs (170) are respectively connected to the positive and negative electrodes of the electrode assembly (160), and may 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. (3) Electrode lead 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. The electrode lead (180) is connected to the electrode assembly (160) and may protrude to the outside of the outer material (110) via the sealing portion (150). Specifically, one end of the electrode lead (180) is 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 outer material (110) via the terrace portion (150). 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 to the outside of the outer material (110). Therefore, 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 outer material (110) may serve as a terminal portion and be electrically connected to an external terminal. One surface of the electrode lead (180) that is in direct contact with the lead film (190) and / or the gas induction unit (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 induction unit (200) can be secured. (4) Lead film According to one embodiment of the present invention, the lead film (190) prevents electricity generated from the electrode assembly (160) from flowing to the outer case (110) through the electrode lead (180) and can maintain the sealing of the outer 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 induction 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. The lead film (190) may be arranged to surround the outer circumference of the electrode lead (180) and the gas induction unit (200). Specifically, the electrode lead (180) and the gas induction unit (200) may be in contact with each other at one side, and at least a portion of the electrode lead (180) and the gas induction unit (200) may be surrounded by the lead film (190). The lead film (190) may be positioned limited to the sealing portion (150) where the first case (120) and the second case (130) of the outer material (110) are heat-sealed, and may adhere the electrode lead (180) and the gas induction unit (200) to the outer material (110). The lead film (190) may be placed between the electrode lead (180) and / or the gas induction unit (200) and the outer material (110). For example, as illustrated in FIG. 2, the lower case (110), the lead film (190), the electrode lead (180), the gas induction unit (200), the lead film (190), and the upper case (110) may be sequentially stacked in the sealing unit (150) area. 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. 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. 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. The pouch adhesive layer may be a layer that directly contacts the outer material (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. (5) Gas induction unit According to one embodiment of the present invention, the gas induction unit (200) is for discharging gas from the inside of the outer material (110) to the outside, and may include a permeation unit (230) provided on the outside of the outer material (110) and one or more gas passages (240) extending from the permeation unit (230) toward the electrode assembly (160) via the sealing unit. As illustrated in FIG. 2, the gas induction unit (200) of the present invention may be disposed between the electrode lead (180) and the lead film (190). In this case, in the area between the electrode lead (180) and the lead film (190), where the gas induction unit (200) is disposed, the electrode lead (180) and the lead film (190) do not come into direct contact, and in the area where the gas induction unit (200) is not disposed, the electrode lead (180) and the lead film (190) may come into direct contact. Hereinafter, the gas induction unit (200) of the present invention will be described in more detail with reference to FIGS. 3 and 4. FIG. 3 is a cross-sectional view of a pouch-type secondary battery before the interface between the gas induction unit (200) and the lead film (190) is opened, and FIG. 4 is a cross-sectional view of a pouch-type secondary battery after the interface between the gas induction unit (200) and the lead film (190) is opened. As illustrated in FIGS. 3 and 4, the interface between the gas induction unit (200) and the lead film (190) is normally not open, and when the pressure inside the outer casing (110) increases, the interface between the gas induction unit (200) and the lead film (190) is opened along the gas path (240), thereby forming a gas discharge path (250). The gas inside the outer casing (110) can move to the permeation unit (230) along the gas discharge path (250) on the gas path (240), and at this time, when a gas pocket is formed on the permeation unit (230), the gas can permeate the lead film (190) and be discharged to the outside of the outer casing (110). As a result, the internal pressure of the outer casing (110) can be lowered, thereby preventing explosion or ignition of the secondary battery. As illustrated in FIGS. 3 and 4, the gas induction unit (200) of the present invention includes an adhesive resin layer (210) that is in contact with the electrode lead (180), and a permeable resin layer (220) that is disposed on the adhesive resin layer (210). The adhesive resin layer (210) is in contact with the electrode lead (180) and may be used to adhere the gas induction unit (200) to the electrode lead (180). As illustrated in FIGS. 3 and 4, the gas induction unit (200) includes an adhesive resin layer (210) that is in contact with the electrode lead (180) and a permeable resin layer (220) that is disposed on the adhesive resin layer (210). The adhesive resin layer (210) is in contact with the electrode lead (180) and may be used to adhere the gas induction unit (200) to the electrode lead (180). In one aspect, as shown in FIG. 3, the adhesive resin layer (210) of the gas induction unit (200) may be formed so that the end in the outer direction (E) of the outer material is longer than the end in the outer direction (E) of the permeable resin layer (220). Accordingly, a structure may be formed in which the adhesive resin layer (210) is in direct contact with the lead film (190) at the end in the outer direction (E) of the gas induction unit (200). Independently of this, the end of the lead film (190) protruding in the outer direction (E) of the outer material may be positioned to protrude further outward (E) than the end of the adhesive resin layer (210) in the same direction and come into direct contact with the electrode lead (180). In addition, independently of this, the end of the lead film (190) protruding in the outer direction (E) of the outer material may be arranged to protrude further outward (E) than the end of the permeable resin layer (220) in the same direction. When the adhesive resin layer (210) is formed to protrude further outward (E) of the outer casing than the permeable resin layer (220), or when the lead film (190) is formed to protrude further outward than one end of the permeable resin layer (220) and / or the adhesive resin layer (210) in the outer casing, the adhesive strength between the electrode lead (180) and the gas induction portion (200), and between the electrode lead (180) and the lead film (190) can be excellent, and thus, a decrease in durability due to an increase in internal pressure can be prevented, and since it is easy to secure the area of ​​the permeable portion (230) on the permeable resin layer (220), stable gas discharge can be possible. In another aspect, as shown in FIG. 5, the lead film (190) may be arranged so that one end protruding in the case outer direction (E) protrudes further than the case outer direction (E) end of the gas induction unit (200) and comes into direct contact with the electrode lead (180). Independently, the outer direction (E) ends of the two layers on the gas induction unit (200) may be formed to coincide. In another aspect, as shown in FIG. 6, the adhesive resin layer (210) may be formed such that one end protruding in the case outer direction (E) protrudes further than the case outer direction (E) end of the permeable resin layer (220), but the outer direction (E) end of the adhesive resin layer (210) matches the outer direction (E) end of the lead film (190). In this case, the lead film (190) may have a structure in which it does not directly contact the electrode lead (180) but rather contacts the adhesive resin layer (210). In the case where the arrangement structure of the lead film (190), electrode lead (180) and gas induction unit (200) is formed as in FIG. 3, FIG. 5 or FIG. 6, it may be advantageous in terms of securing durability and securing the area of ​​the permeable unit (230) compared to the case where the lead film (190) is not arranged so that one end protrudes further outward from the outer material (110) than the gas induction unit (200) but is arranged on the permeable resin layer (220) of the gas induction unit (200). However, although it may be arranged as in FIG. 3 most preferably, there is no disadvantage in performance in the structure of FIG. 5 or FIG. 6, and there may be some differences in design and process. The adhesive resin layer (210) may include any material that is easily bonded to the electrode lead (180). Specifically, the adhesive resin layer (210) may include a modified polyolefin-based resin. When the adhesive resin layer (210) includes a modified polyolefin-based resin, the adhesive strength between the gas induction unit (200) and the electrode lead (180) is improved, so that even when the pouch-type secondary battery is stored in a high-temperature environment, the gas induction unit (200) is prevented from being detached from the electrode lead (180) and pushed out of the pouch, or the electrolyte inside the pouch from leaking. The adhesive resin layer (210) may include at least one of an acid-modified polyolefin and a silane-modified polyolefin. 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 induction 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. 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. The adhesive resin layer (210) 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 (210) may include, but is not limited to, plasma-treated polypropylene (PP). The thickness of the adhesive resin layer (210) may be 5 µm to 130 µm, specifically 30 µm to 120 µm, and more specifically 30 µm to 80 µm. When the thickness of the adhesive resin layer (210) satisfies the above numerical range, the adhesive resin layer (210) is melted within a set production time (tact time), so that the gas induction unit (200) and the electrode lead (180) can be easily fused together. The permeable resin layer (220) may be a layer in contact with the lead film (190). The permeable resin layer (220) may include at least one of polytetrafluoroethylene (PTFE) and polyimide (PI), but is not limited thereto. Among these, when the permeable resin layer (220) includes polyimide, the adhesive force between the permeable resin layer (220) and the lead film (190) is reduced, which is preferable in that a gas discharge path (250) can be formed when the internal pressure of the case (110) increases. The thickness of the permeable resin layer (220) may be 40 ㎛ to 100 ㎛, specifically 40 ㎛ to 90 ㎛, and more specifically 45 ㎛ to 75 ㎛. When the thickness of the permeable resin layer (220) satisfies the above numerical range, the permeable resin layer (220) may not melt during the sealing process, and when the internal pressure of the case (110) increases, the interface between the permeable resin layer (220) and the lead film (190) may be lifted to form a gas discharge path (250). Meanwhile, the ratio (D1 / D2) of the thickness (D1) of the adhesive resin layer to the thickness (D2) of the permeable resin layer (220) may be 0.4 to 2.0, specifically 0.4 to 1.5, and more specifically 0.4 to 1.0. When the ratio (D1 / D2) satisfies the above numerical range, when the internal pressure of the case (110) increases, the interface between the permeable resin layer (220) and the lead film (190) is lifted to form a gas discharge path, while improving the adhesive strength between the gas induction unit (200) and the electrode lead (180). The above-described transparent resin layer (220) and adhesive resin layer (210) can be laminated through thermocompression, and can be combined after forming an adhesive layer therebetween, or can be in the form of a tape in which an adhesive is applied to one surface of the transparent resin layer (220) or the adhesive resin layer (210) and a release film is attached, and can be combined after the release film is removed. There is no particular limitation on the method for laminating the above-described transparent resin layer (220) and adhesive resin layer (210), and in addition to the above-described method, any method can be applied as long as the two layers can adhere well to each other. (6) Reinforcing film According to one embodiment of the present invention, the reinforcing film (300) is disposed on the lead film (190) so as to cover at least a portion of the permeable portion (230) of the gas induction portion (200), thereby preventing whitening and electrolyte seepage. The above pouch-type secondary battery (100) has a series of mechanisms in which, when the internal pressure increases, the interface between the gas induction unit (200) and the lead film (190) is opened, and the laminates including the lead film (190) and the outer covering (110) thereon are lifted upward only in the portion where the gas induction unit (200) is arranged, thereby forming a gas discharge path (250), and the gas inside is discharged to the outside by passing through the lead film (190) in the permeation portion (230) through the gas discharge path (250) thus formed. When this gas discharge mechanism is repeated, the lead film (190) located on the gas-permeable portion, i.e., the permeable portion (230) of the gas induction portion (200), is continuously subjected to tension, and as the internal pressure increases, the tension applied to the lead film (190) increases, and a whitening phenomenon may occur in the relevant portion. Specifically, the whitening phenomenon may occur when the molecular structure inside the film is deformed due to the continuous stretching of the lead film (190), the internal stress increases due to the deformation, and the bonding force between molecules is weakened accordingly, and in the portion where the bonding force between molecules is weakened. Meanwhile, when the gas is discharged and the internal pressure is lowered again, that is, when a series of charge / discharge reactions are completed and the battery is placed in a storage state and all the gas inside is discharged, the lifted lead film (190) returns to its original state and the gas discharge path (250) is closed again. The closure of the gas discharge path (250) can minimize the possibility of the electrolyte leaking to the outside. However, as described above, a part where the bonding force between molecules is weakened occurs inside the lead film (190), and the electrolyte can infiltrate through this part. This can cause a problem in that the electrolyte may be observed to seep through the permeable part (230) of the gas induction part (200) on the lead film (190), or in severe cases, leakage may occur. Once the electrolyte seeps through or leaks, the possibility of moisture infiltration from the outside increases significantly. In addition, if the above phenomenon is repeated, the electrode lead (180) may corrode, and if the internal pressure increases, a problem may occur in which the lead film (190) bursts around the part where the bonding strength is weakened. Accordingly, the present invention aims to solve the above problem by introducing a reinforcing film (300) on the permeable portion (230) of the gas induction portion (200), which is an area through which gas is permeated on the lead film (190), thereby ensuring durability by suppressing deterioration of the gas induction portion (200) and the lead film (190) due to continuous gas discharge. Referring to FIGS. 3 and 4, a gas induction member (200) is placed on an electrode lead (180), a lead film (190) is placed on the gas induction member (200), and the reinforcing film (300) is placed on the lead film (190), but is placed on a surface where the lead film (190) is exposed outside the terrace member (150) of the outer material (110). As shown in FIG. 4, when the internal pressure increases, the interface between the gas induction part (200) and the lead film (190) is opened, forming a gas discharge path (250). The permeation part (230) of the gas induction part (200) is arranged at the outermost side of the gas induction part (200) outside the terrace part (150) as shown in FIG. 7, so that gas is discharged through the lead film (190) of this part. By placing a reinforcing film (300) on the lead film (190) of the part where this gas is discharged, even if continuous gas discharge occurs, electrolyte seepage or whitening due to continuous stretching of the lead film (190) is prevented, thereby enhancing durability. The reinforcing film (300) may have an area based on the outer circumference of the reinforcing film (300) that is 100% to 500% of the area of ​​the permeable portion (230) of the gas induction portion (200). That is, the reinforcing film (300) may be arranged to cover at least the entire area of ​​the permeable portion (230), and the area (S) of the permeable portion (230) A) can be arranged to cover up to 500%, preferably 400%, 350%, or 300% of the area of ​​the transmission portion (230). As long as the area of ​​the reinforcing film (300) covering the transmission portion (230) is designed to cover the entire area, there is no particular problem, but it may be disadvantageous in terms of design, such as the sealing process and the thickness of the terrace portion after sealing, so it may be desirable to design it to satisfy the above-mentioned range. In addition, in order to effectively suppress the electrolyte seepage phenomenon and prevent the whitening phenomenon due to stretching, it is desirable to design the area of ​​the reinforcing film (300) to be 110% or more, 130% or more, or 150% or more of the area of ​​the transmission portion (230). In addition, when designing the area covering the transmission section (230), the reinforcing film (300) can be arranged so that a portion of the reinforcing film exceeding the area of ​​the transmission section (230) can also cover a portion of the gas path (240). That is, in order to effectively prevent electrolyte seepage and whitening due to stretching, in the case where the area of ​​the permeation portion (230) of the gas induction portion (200) is designed to exceed the area of ​​the permeation portion (230) of the gas induction portion (200), it may be desirable to design the reinforcement film (300) to be wide in the width direction of the electrode lead (180) and long in the length direction of the electrode lead (180), and preferably, it may be arranged to cover not only the permeation portion (230) but also the gas passage (240), and further, it may be designed to extend to a portion adjacent to the sealing portion (151). According to one embodiment of the present invention, the reinforcing film (300) may have a hollow (301) formed therein, as shown in FIGS. 8 and 9, and the hollow may have a square (FIG. 8) or circular (FIG. 9) shape in a plan view. The area of ​​the hollow (301) inside the reinforcing film (300) may have a greater influence on the gas discharge performance or the protection of the lead film (190) than the shape thereof, and in terms of securing the gas discharge area through the formation of the hollow (301), a shape that can secure the optimal area can be appropriately selected by considering the configuration of the electrode assembly designed together or the specifications of the cell. Specifically, the area of ​​the hollow (301) may be smaller than the area of ​​the permeation portion (230), and preferably, the area of ​​the hollow (301) may be 50% to 90% of the area of ​​the permeation portion (230). The greatest expected effect of forming the hollow (301) lies in the gas discharge performance, but the expected effect of suppressing the whitening phenomenon and electrolyte seepage phenomenon to be obtained by covering the reinforcing film (300) should also be taken into consideration, and therefore, the area of ​​the hollow (301) is preferably appropriately designed at a level of 50% to 90% of the area of ​​the permeation portion, which is the above range, and more preferably, the hollow (301) may be formed in a range of 50% to 85%, and even more preferably, 50% to 80%. The above-mentioned hollow may have various shapes as described above, but when designed in a square shape, the length of the hollow in the protruding direction of the electrode lead may be designed to be shorter than the length of the transmission portion, and the width of the hollow in the width direction of the electrode lead may be designed to be less than the width of the transmission portion. As described in relation to the area of ​​the hollow (301), it may be desirable that the width and length of the hollow (301) are also designed in the same sense, and it is desirable to design it taking into account that the length of the hollow in the longitudinal direction of the electrode lead is preferably shorter than the length of the transmission portion. In one aspect, the reinforcing film (300) may be inserted between the outer material (110) and the lead film (190) in the sealing portion (151) with its end extending in the inner direction (I) of the outer material, and may be extended to occupy a portion of the width of the sealing portion (151). In this case, the sealing strength may be improved, and thereby the durability may be improved by maintaining the sealing strength even when the interface between the lead film (190) and the gas induction portion (200) is repeatedly opened, thereby preventing an unintended venting phenomenon. The insertion part (not shown) of the above reinforcing film (300) has a sealing width (W) of the sealing part (151). S ) may be 0.05 to 0.90. When the insertion portion (301) is formed so that the length ratio satisfies the range, it is expected that the sealing strength can be secured at a level that does not lower the fairness of the sealing process. That is, when the reinforcing film (300) is inserted deep within the sealing width so that the insertion portion (not shown) covers the entire sealing portion (151), peeling may occur at the interface between the reinforcing films (300) having a multi-layer structure. Therefore, by making the end of the reinforcing film (300) in the inner direction (I) of the outer material cover only a part of the sealing width, it is possible to prevent the problem of interface peeling as described above by covering the sealing portion (151). To further enhance this effect, preferably, the length ratio may be 0.07 or more, 0.09 or more, 0.10 or more, or 0.11 or more, and may also be 0.85 or less, 0.83 or less, 0.80 or less, 0.79 or less, or 0.78 or less. In one aspect, the reinforcing film (300) may include at least one selected from the group consisting of a polyester resin, a polyolefin resin, a polyamide resin, and a polycarbonate resin. Preferably, the polyester resin may include polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), and preferably polyethylene naphthalate (PEN). In addition, the polyolefin resin may include polyethylene (PE), polypropylene (PP), or a resin modified with an acid or silicone thereof, and an unstretched, non-stretched polyolefin may be applied. In addition, nylon or polycarbonate may also be applied. It is preferable to select the material of the reinforcing film in consideration of the tensile strength, gas barrier properties, etc. of the material, and an appropriate material may be selected in consideration of whether or not a hollow portion of the reinforcing film is to be formed. In one aspect, the reinforcing film (300) may specifically have a two-layer structure as in FIG. 10, or a three-layer structure as in FIG. 11. When the reinforcing film (300) has a two-layer structure, it may include a protective layer (310) and an adhesive layer (320) disposed between the protective layer (310) and the lead film (190). In addition, when the reinforcing film (300) has a three-layer structure, it may include a protective layer (310), an adhesive layer (320) disposed between the protective layer (310) and the lead film (190), and an insulating layer (330) disposed on the outermost surface of the protective layer (310). In the case of the above protective layer (310), as described above, it may include at least one selected from the group consisting of polyester-based resin, polyolefin-based resin, polyamide-based resin, and polycarbonate-based resin, and the adhesive layer (320) and the insulating layer (330) may each independently include at least one selected from the group consisting of acid-modified polypropylene (PPa) and acid-modified polyethylene (Pea). When acid-modified polypropylene or acid-modified polyethylene is applied as the adhesive layer (320), it has excellent adhesion to the lead film (190), thereby providing excellent durability, and when acid-modified polypropylene or acid-modified polyethylene is applied as the insulating layer (330), it can greatly contribute to the ability to prevent moisture penetration from the outside. Here, the 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 that has been subjected to a carboxyl group introduction (graft modification) by reacting an unsaturated carboxylic acid with a polyolefin resin. 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. 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). In one aspect, the reinforcing film (300) can be appropriately combined in terms of a laminated structure and hollow formation. When a hollow (301) is formed in the reinforcing film (300), the laminated structure of the reinforcing film (300) can be applied to both a two-layer structure and a three-layer structure. When a hollow (301) is formed, a minimum gas discharge area can be secured, so the gas discharge area is secured through the hollow (301), and the reinforcing film (300) outside the hollow (301) performs the functions of suppressing whitening and electrolyte seepage, thereby achieving the expected effects of the present invention. In the case where a hollow space (301) is not formed in the above reinforcing film (300), it is preferable not to apply a reinforcing film (300) having a three-layer structure. A reinforcing film (300) having a two-layer structure does not significantly slow down the gas discharge rate even if it covers the area through which gas is permeated, and even if it slows down, it can be seen as having sufficient performance in maintaining cell performance and preventing swelling. However, since the gas discharge rate slows down rapidly when a three-layer structure is formed, it is preferable to avoid a three-layer structure in which a hollow space is not formed when designing a reinforcing film (300). Preferably, the reinforcing film may include an adhesive layer in contact with the lead film; and a protective layer disposed on the adhesive layer and containing a polyester-based resin; or, the reinforcing film may include an adhesive layer in contact with the lead film, in which a hollow portion is formed; and a protective layer disposed on the adhesive layer and containing a polyester-based resin. As another example, the reinforcing film may include a hollow portion formed therein and an adhesive layer in contact with the lead film; a protective layer disposed on the adhesive layer and including a polyester resin; and an insulating layer disposed on the protective layer. (7) Electrolyte The pouch-type secondary battery (100) according to the present invention may further include an electrolyte (not shown) injected into the exterior material (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, an oxide type, or a polymer type, and such a solid electrolyte may have flexibility that allows it to be easily deformed by an external force. 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. Examples and Comparative Examples Example 1 (1) Manufacturing of exterior materials A polyethylene terephthalate (PET) film measuring 266 mm wide, 50 m long, and 12 ㎛ thick and a nylon film measuring 266 mm wide, 50 m long, and 25 ㎛ thick were laminated on one side of an aluminum alloy film measuring 266 mm wide, 50 m long, and 60 ㎛ thick, and a polypropylene film measuring 266 mm wide, 50 m long, and 80 ㎛ thick 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 nylon film are the substrate layer, the aluminum alloy thin film is the gas barrier layer, and the polypropylene film is the sealant layer. The above pouch film laminate was molded to manufacture an outer material including a receiving portion and a sealing portion. (2) Manufacturing of pouch-type secondary batteries 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. 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 housed in the outer case with the tip of the electrode lead extended outward, and the electrolyte was poured. A 50 μm thick polytetrafluoroethylene tape (permeable resin layer) was attached to a 40 μm thick acid-modified polypropylene film (adhesive resin layer) on the upper surface of the electrode lead to form a gas induction section. Next, a 200 μm thick lead film was laminated on the lower surface of the electrode lead and the upper surface of the gas induction unit, 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. Finally, a 40 ㎛ thick acid-modified polypropylene film and a 12 ㎛ thick polyethylene naphthalate film were sequentially laminated on the upper surface of the lead film on which the gas induction section was formed, particularly on the upper surface of the lead film on which the gas induction section's permeable portion, which is positioned on the outside of the outer material relative to the sealing position, was formed to form a reinforcing film. Afterwards, the sealing part of the above outer material was sealed for 2 seconds under the conditions of a seal bar area of ​​200 mm × 10 mm, 220°C, and 0.27 MPa, and then left at 60°C for 4 hours to manufacture a pouch-type secondary battery. At this time, the part where the permeable part of the gas induction part among the terrace parts is formed has a structure in which a lower case / lead film / electrode lead / gas induction part / lead film / upper case are sequentially laminated. Example 2 A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a hollow portion was formed in the reinforcing film so that the hollow portion area was 50% of the permeable portion area of ​​the gas induction portion. Example 3 A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a hollow portion was formed in the reinforcing film so that the hollow portion area was 75% of the permeable portion area of ​​the gas induction portion. Example 4 A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a 40 μm thick acid-modified polypropylene film was additionally laminated on the upper surface of the polyethylene naphthalate film of the reinforcing film, and a hollow portion was formed so that the hollow area was 50% of the area of ​​the permeable portion of the gas induction portion. Example 5 A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a 40 μm thick acid-modified polypropylene film was additionally laminated on the upper surface of the polyethylene naphthalate film of the reinforcing film, and a hollow portion was formed so that the hollow area was 75% of the area of ​​the permeable portion of the gas induction portion. Example 6 A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a 100 μm thick polypropylene film was used instead of the polyethylene naphthalate film of the reinforcing film. Example 7 A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a 200 μm thick polypropylene film was used instead of the polyethylene naphthalate film of the reinforcing film. Comparative Example 1 A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a reinforcing film was not formed. Experimental Example 1: Measurement of gas emission rate The gas emission rate was measured for each pouch-type secondary battery manufactured in Examples 1 to 7 and Comparative Example 1. Specifically, CO2 was injected into the pouch-type secondary battery using pressure equipment from ITS Corporation to increase the pressure inside the pouch to 1.5 atm, and the amount of gas emitted for 24 hours was measured, and the results are shown in Table 1 below. Experimental Example 2: Measuring the operating pressure of the gas induction unit The operating pressure of the gas induction unit was measured for each of the pouch-type secondary batteries manufactured in Examples 1 to 7 and Comparative Example 1. Specifically, while injecting CO2 into the interior of a pouch-type secondary battery using pressure equipment from ITS Corporation and increasing the pressure inside the pouch by 0.1 atm units, the battery was left for 24 hours at each pressure, and the pressure at which the permeation section of the gas induction section was completely deformed (when the entire permeation section was lifted) was measured, and the results are shown in Table 1 below. Experimental Example 3: Occurrence of whitening and electrolyte penetration For each of the pouch-type secondary batteries manufactured in Examples 1 to 7 and Comparative Example 1, CO2 was injected into the pouch-type secondary batteries using pressure-resistant equipment from ITS Corporation to increase the pressure inside the pouch to 2.0 atm, and then, for 24 hours, the whitening (stretching) phenomenon at the edge of the gas induction section was calculated using the following mathematical formula 1, and the presence of electrolyte seepage was confirmed. [Mathematical Formula 1] Whitening phenomenon (%) = [Whitening occurrence length on lead film (mm)] / [Total edge length of gas induction section (mm)] Gas discharge rate (cc / day)Operating pressure (atm)Whitening phenomenon (%)Electrolyte immersionExample 15.30.80XExample 28.10.86.15XExample 38.90.812.2XExample 44.60.86.1XExample 57.40.812.2XExample 68.40.80XExample 76.80.80XComparative example 116.80.897.6O According to Table 2 above, in the cases of Examples 1 to 7 in which a reinforcing film was applied to the upper surface of the lead film on the permeable portion of the gas induction portion, it was confirmed that the gas discharge rate was maintained at an appropriate level, while the degree of whitening phenomenon was significantly low or did not occur at all, and the electrolyte seepage phenomenon also did not occur. However, in the case of Comparative Example 1, although the gas discharge rate was fast, the whitening phenomenon occurred extremely severely and the electrolyte seepage phenomenon was confirmed to occur. [Explanation of symbols] 100: Pouch-type secondary battery 110: Exterior material 120: Case 1 122: Cup 124: Reception area 130: Case 2 132: Cup 140: Bridge section 150: Terrace 151: Sealing part 160: Electrode assembly 170: Electrode tab 172: Positive tab 174: Negative tab 180: Electrode lead 182: Positive lead 184: Negative lead 190: Lead Film 200: Gas induction unit 210: Adhesive resin layer 220: Permeable resin layer 230: Transmission section 240: Gas Euro 250: Gas discharge path 300: Reinforcement film 301: Hollow 310: Protective layer 320: Adhesive layer 330: Insulating layer

Claims

1. Electrode assembly; An outer material including a receiving portion for receiving the electrode assembly and a terrace portion formed along the periphery of the receiving portion, the terrace portion having a sealing portion with a portion of the width thereof sealed; An electrode lead electrically connected to the electrode assembly and protruding outward from the outer surface of the outer material; A lead film disposed between the electrode lead and the outer material; A gas induction unit disposed between the electrode lead and the lead film, including a permeable portion provided on the outside of the outer material and one or more gas passages extending from the permeable portion toward the electrode assembly via the sealing portion; and A pouch-type secondary battery, comprising a reinforcing film disposed on a lead film so as to cover at least a portion of the above-mentioned transmission portion.

2. In paragraph 1, The above secondary battery, A pouch-type secondary battery, wherein the interface between the lead film and the gas induction section is opened along the gas path due to an increase in internal pressure of the outer material, thereby providing a gas discharge path.

3. In claim 1, The above reinforcing film, Including an insertion portion occupying a portion of the width of the above sealing portion, A pouch-type secondary battery, wherein the above insertion portion is a region where one end of the reinforcing film extends inwardly toward the outer material and is inserted between the outer material of the sealing portion and the lead film.

4. In claim 1, The above reinforcing film, A pouch-type secondary battery having an area based on the outer circumference that is 100% to 500% of the area of ​​the above-mentioned permeable portion.

5. In claim 1, The above reinforcing film, A pouch-type secondary battery arranged on the lead film so that the entire permeable portion of the gas induction portion and a portion of the gas path are covered.

6. In claim 1, The above reinforcing film, A pouch-type secondary battery in which a cavity is formed, and the area of ​​the cavity is smaller than the area of ​​the transmission portion.

7. In claim 1, The above reinforcing film, A pouch-type secondary battery in which a cavity is formed, and the area of ​​the cavity is 50% to 90% of the area of ​​the transmission section.

8. In claim 1, The above reinforcing film, A pouch-type secondary battery comprising at least one selected from the group consisting of polyester resin, polyolefin resin, polyamide resin, and polycarbonate resin.

9. In claim 1, The above reinforcing film, An adhesive layer in contact with the lead film; and a protective layer disposed on the adhesive layer; A pouch-type secondary battery, wherein the protective layer comprises at least one selected from the group consisting of polyester resin, polyolefin resin, polyamide resin, and polycarbonate resin.

10. In claim 1, The above reinforcing film, A hollow was formed, An adhesive layer in contact with the lead film; a protective layer disposed on the adhesive layer; and an insulating layer disposed on the protective layer; A pouch-type secondary battery, wherein the protective layer comprises at least one selected from the group consisting of polyester resin, polyolefin resin, polyamide resin, and polycarbonate resin.

11. In claim 1, The above gas induction part A pouch-type secondary battery having a structure in which an adhesive resin layer and a permeable resin layer are laminated from the upper surface of an electrode lead.

12. In claim 11, The above adhesive resin layer A pouch-type secondary battery, wherein one end of the outer shell protrudes further than one end of the permeable resin layer protruding in the outer shell.

13. In claim 11, The above lead film, A pouch-type secondary battery, wherein one end of the outer shell protrudes further than one end of the permeable resin layer protruding in the outer shell.

14. A plurality of pouch-type secondary batteries; and a packaging for accommodating the secondary batteries, The above pouch-type secondary battery, electrode assembly; An outer material including a receiving portion for receiving the electrode assembly and a terrace portion formed along the periphery of the receiving portion, the terrace portion having a sealing portion with a portion of the width thereof sealed; An electrode lead electrically connected to the electrode assembly and protruding outward from the outer surface of the outer material; A lead film disposed between the electrode lead and the outer material; A gas induction unit disposed between the electrode lead and the lead film, including a permeable portion provided on the outside of the outer material and one or more gas passages extending from the permeable portion toward the electrode assembly via the sealing portion; and A battery pack comprising a reinforcing film disposed on a lead film so as to cover at least a portion of the above-described transmission portion.

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