Pouch-type secondary battery

Abstract

Provided is a pouch-type secondary battery comprising: an electrode assembly; a battery case including an accommodation part accommodating the electrode assembly, and a terrace part formed along the circumference of the accommodation part; an electrode lead which is connected to the electrode assembly, and which protrudes to the outside of the battery case through the terrace part; a lead film disposed between the electrode lead and the battery case; and a gas guide film disposed between the electrode lead and the lead film, wherein the terrace part includes a sealing part as a portion thereof sealed along the circumference of the accommodation part, and the lead film includes inorganic particles. The pouch-type secondary battery can have improved gas discharge performance due to the inorganic particles being contained in the lead film through which gas passes.

Description

pouch-type secondary battery

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0066764, filed May 22, 2024, the entire contents of which are incorporated herein by reference.

[0003]

[0004] Technology field

[0005] The present specification relates to a pouch-type secondary battery, and more specifically, to a pouch-type secondary battery provided with a lead film including inorganic particles and a gas-inducing film.

[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 gas pressure within the pouch increases, the pouch can vent, potentially leading to an explosion or fire.

[0010] 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.

[0011]

[0012] In this specification, it is intended to provide a pouch-type secondary battery having a gas discharge function provided by a gas induction film, which includes inorganic particles in a lead film through which gas is directly permeable, thereby removing HF gas generated by moisture and preventing corrosion of an electrode lead, and having an improved gas discharge rate.

[0013]

[0014] [1] In one aspect, a pouch-type secondary battery is provided, comprising: an electrode assembly; a battery case including a receiving portion for receiving the electrode assembly, and a terrace portion formed along a periphery of the receiving portion; an electrode lead connected to the electrode assembly and protruding to the outside of the battery case via the terrace portion; a lead film disposed between the electrode lead and the battery case; and a gas induction film disposed between the electrode lead and the lead film; wherein the terrace portion includes a sealing portion having a portion sealed along a periphery of the receiving portion, and the lead film includes inorganic particles.

[0015] [2] In the above [1], the pouch-type secondary battery may be provided with a gas permeable portion formed on the outside of the sealing portion at the interface between the lead film and the gas induction film, and a gas path formed through the sealing portion such that the gas permeable portion and the inside of the battery case are connected to each other.

[0016] [3] In the above [1] and / or [2], in the pouch-type secondary battery, when gas is generated inside the battery case, the interface between the lead film and the gas induction film may be opened, so that the generated gas may pass through the gas path and be discharged to the outside through the lead film on the gas permeable portion.

[0017] [4] In at least one of the above [1] to [3], the lead film has a structure in which a pouch adhesive layer, a core layer, and a lead adhesive layer are sequentially laminated, and the inorganic particles may be included in one or more layers selected from the group consisting of the core layer and the lead adhesive layer.

[0018] [5] In at least one of the above [1] to [4], the lead film has a structure in which a pouch adhesive layer, a core layer, and a lead adhesive layer are sequentially laminated, and the inorganic particles may be included in the core layer.

[0019] [6] In at least one of the above [1] to [5], the inorganic particles may be further included in the lead adhesive layer.

[0020] [7] In at least one of the above [1] to [6], the inorganic particles may include at least one selected from the group consisting of CaCO3, Ca(OH)2, CaCl2, CaO, KOH, NaOH and Na2CO3.

[0021] [8] In at least one of the above [1] to [7], the inorganic particles may be included in an amount of 1 wt% to 20 wt% based on the total weight of the lead film.

[0022] [9] In at least one of the above [1] to [8], the lead film may be arranged so that one end protruding toward the outside of the battery case protrudes further than one end of the gas induction film protruding toward the outside of the battery case and directly contacts the electrode lead.

[0023]

[0010] In at least one of the above [1] to [9], the gas induction film 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.

[0024]

[0011] In the above

[0010] , the adhesive resin layer may include at least one selected from the group consisting of acid-modified polypropylene (PPa) and acid-modified polyethylene (Pea).

[0025]

[0012] In the above

[0010] and / or

[0011] , the permeable resin layer may include at least one selected from the group consisting of polyimide (PI) and polytetrafluoroethylene (PTFE).

[0026]

[0013] In at least one of the above

[0010] to

[0012] , the ratio (D1 / D2) of the thickness (D1) of the adhesive resin layer to the thickness (D2) of the permeable resin layer may be 0.4 to 2.0.

[0027]

[0014] In at least one of the above

[0010] to

[0013] , the adhesive resin layer may have one end protruding toward the outside of the battery case more than one end of the transparent resin layer protruding toward the outside of the battery case.

[0028]

[0029] A pouch-type secondary battery according to the present specification has a function of discharging gas through a gas path and a gas permeable portion formed between a gas induction film and a lead film, and by including inorganic particles in the lead film through which gas is directly permeated in the gas permeable portion, corrosion of an electrode lead is prevented by removing HF gas generated by moisture, thereby improving the durability of the pouch-type secondary battery. In addition, since the inorganic particles are included in the lead film, the porosity of the film is increased, and accordingly, the rate of gas discharge is improved without increasing the amount of moisture infiltration, thereby improving gas discharge performance, thereby providing a pouch-type secondary battery with improved safety.

[0030]

[0031] The drawings attached to the 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 the matters described in such drawings.

[0032] Figure 1 is an exploded assembly diagram of a pouch-type secondary battery according to one embodiment of the present specification.

[0033] Figure 2 is a cross-sectional view of a sealed pouch-type secondary battery.

[0034] 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 film is opened.

[0035] Fig. 4 is an example of an enlarged cross-sectional view of part A of box 2, specifically showing the lead film before the interface between the lead film and the gas induction film is opened.

[0036] Fig. 5 is an example of an enlarged cross-sectional view of part A of box 2, specifically showing the lead film before the interface between the lead film and the gas induction film is opened.

[0037] Fig. 6 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 film is open.

[0038] Figure 7 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.

[0039] Figure 8 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.

[0040] Figure 9 is an example of a top perspective view in the B direction for part A of box in Figure 2.

[0041] Fig. 10 is another example of a top perspective view in the B direction for part A of box in Fig. 2.

[0042]

[0043] The advantages and features of the invention described herein, and the methods for achieving them, will become clearer with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In this specification, the description of “A and / or B” means A, or B, or A and B.

[0048] In this specification, “%” means weight percent unless explicitly indicated otherwise.

[0049]

[0050] In one aspect of the present specification, a pouch-type secondary battery includes: an electrode assembly; a battery case including a receiving portion for receiving the electrode assembly, and a terrace portion formed along a periphery of the receiving portion; an electrode lead connected to the electrode assembly and protruding to the outside of the battery case via the terrace portion; a lead film disposed between the electrode lead and the battery case; and a gas induction film disposed between the electrode lead and the lead film; wherein the terrace portion includes a sealing portion having a portion sealed along a periphery of the receiving portion, and the lead film is characterized in that it includes inorganic particles.

[0051] In general, the gas discharge performance of a gas induction film is determined by the properties of the material constituting the gas induction film, and depending on the properties 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 induction film plays an important role.

[0052] Factors that can improve gas discharge performance regardless of the material include the area of ​​the gas permeable portion formed on the gas induction film and the design of the width of the gas path formed on the gas induction film so as to connect from the inside of the battery case to the gas permeable portion, thereby improving gas discharge performance and moisture penetration and electrolyte leakage prevention performance.

[0053] The materials and design of the gas-inducing film described above may limit the ability to discharge gases generated within pouch-type secondary batteries when cells using materials that inevitably generate large amounts of gas are used. Furthermore, pouch-type secondary batteries utilizing gas-inducing films and thus possessing a gas-discharging function are inherently vulnerable to moisture infiltration and corrosion of electrode leads due to hydrofluoric acid (HF) gas generated as a side reaction in the electrolyte.

[0054] In this specification, it is intended to provide a pouch-type secondary battery with significantly improved durability and safety by including inorganic particles in a lead film that directly transmits gas to the outside and continuously comes into contact with the generated gas, so as to prevent corrosion of the electrode lead by HF gas generated internally while further improving gas emission performance and limiting the amount of moisture infiltration.

[0055]

[0056] First, each component of the pouch-type secondary battery of the present invention will be described in more detail with reference to the drawings.

[0057] FIG. 1 is an exploded assembly diagram of a pouch-type secondary battery (100) according to one embodiment of the present specification, 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 a battery case (110), an electrode assembly (160), an electrode lead (180), a lead film (190), and a gas induction film (200).

[0058]

[0059] (1) Battery case

[0060] In one aspect, the battery case (110) can house an electrode assembly (160) inside. The battery case (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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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 battery case.

[0066] 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).

[0067] 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.

[0068] The sealant layer is intended to completely seal the inside of the battery case, which houses the electrode assembly inside, by thermally bonding the sealing portion when the battery case is sealed. To this end, the sealant layer may be formed of a material having excellent thermal bonding strength.

[0069] 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 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 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.

[0070] 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.

[0071] 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.

[0072]

[0073] Meanwhile, the pouch film laminate may be drawn and stretched by a punch or the like to manufacture a battery case (110). As a result, the 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.

[0074] In one aspect, the 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.

[0075] In another aspect, 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 in 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 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.

[0076] The 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. 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, 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 (not shown).

[0077] 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).

[0078] 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 battery case (110) can secure sufficient sealing strength through thermal bonding.

[0079]

[0080] (2) Electrode assembly

[0081] In one aspect, the electrode assembly (160) can be inserted into the battery case (110) and sealed by the battery case (110) after electrolyte injection.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] The electrode assembly (160) may include an electrode tab (170).

[0086] 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.

[0087]

[0088] (3) Electrode lead

[0089] In one aspect, 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.

[0090] The electrode lead (180) is connected to the electrode assembly (160) and may protrude to the outside of the battery case (110) via the sealing portion (151). 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 battery case (110) via the terrace portion (150).

[0091] 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 copper material coated with nickel (Ni). 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.

[0092] One surface of the electrode lead (180) that is in direct contact with the lead film (190) and / or the gas induction film (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 film (200) can be secured.

[0093]

[0094] (4) Lead film

[0095] In one aspect, 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 can maintain 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 induction film (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.

[0096] The lead film (190) may be arranged to surround the outer circumference of the electrode lead (180) and the gas induction film (200). Specifically, the electrode lead (180) and the gas induction film (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 film (200) may be surrounded by the lead film (190). The lead film (190) may be positioned at the sealing portion (151) where the first case (120) and the second case (130) of the battery case (110) are thermally bonded, and may adhere the electrode lead (180) and the gas induction film (200) to the battery case (110).

[0097] In one aspect, the lead film (190) may be arranged so that one end of the lead film (190) protrudes outwardly from the battery case (110) and protrudes further outward than one end of the gas induction film (200), particularly an adhesive resin layer (210) to be described later, and comes into direct contact with the electrode lead (180). In this way, when the lead film (190) is formed to protrude further outwardly from the battery case (110) than one end of the gas induction film (200), the adhesive force between the electrode lead (180) and the gas induction film (200), and between the electrode lead (180) and the lead film (190), is strong, so that a decrease in durability due to an increase in internal pressure can be prevented, and the area of ​​the gas permeable portion (230) on the gas induction film (200) can be easily secured, so that stable gas discharge can be enabled.

[0098]

[0099] The lead film (190) may be placed between the electrode lead (180) and / or the gas induction film (200) and the battery case (110). For example, as illustrated in FIG. 2, the lower case (110), the lead film (190), the electrode lead (180), the gas induction film (200), the lead film (190), and the upper case (110) may be sequentially stacked in the terrace portion (150) area.

[0100]

[0101] FIGS. 3 to 5 are enlarged cross-sectional views of a portion corresponding to box A of FIG. 2, showing a lead film (190) containing inorganic particles (191). Referring to these, the inorganic particles (191) in the lead film (190) will be described.

[0102] Referring to FIG. 3, in one embodiment of the present invention, a pouch-type secondary battery includes inorganic particles (191) within the lead film (190). In addition, the lead film (190) may have a multilayer structure including one or more layers, as in FIGS. 4 and 5. Specifically, the lead film (190) may include a sequentially laminated pouch adhesive layer (1901), a core layer (1902), and a lead adhesive layer (1903).

[0103] The inorganic particles (191) may be included in one or more layers selected from the group consisting of the core layer (1902) and the lead adhesive layer (1903), and preferably may be included in the core layer (1902). In addition, as shown in FIG. 4, the inorganic particles (191) may be included in the core layer (1902), and may further be included in the lead adhesive layer (1903). For example, as shown in FIG. 5, the inorganic particles (191) may be included in two layers within the lead film (190). However, it may be preferable that the inorganic particles are not included in the pouch adhesive layer (1901). When the pouch adhesive layer also includes inorganic particles, apart from further improving gas discharge performance, the sealing strength is weakened, and therefore, in order to improve the durability of the battery itself due to the adhesive force between the battery case and the lead film, it may be preferable not to include inorganic particles in the pouch adhesive layer. The above-mentioned inorganic particles (191) can function to increase the porosity of the lead film (190) by being included in the lead film (190) so that gas can be discharged better, and since the inorganic particles can absorb hydrofluoric acid gas, it is expected that the function of preventing corrosion of the electrode lead due to hydrofluoric acid gas generated inside the battery will also be significantly improved.

[0104] The above-mentioned inorganic particles may include, for example, at least one selected from the group consisting of CaCO3, Ca(OH)2, CaCl2, CaO, KOH, NaOH, and Na2CO3, preferably may include CaCO3, Ca(OH)2, CaCl2, and / or CaO, and more preferably may include CaCO3, Ca(OH)2, and / or CaO. When such inorganic particles are applied, the absorption performance of hydrofluoric acid gas may be excellent.

[0105] In addition, the inorganic particles may be included in an amount of 1 wt% to 20 wt% based on the total weight of the lead film. Preferably, the inorganic particles may be included in an amount of 2 wt% to 18 wt%, 3 wt% to 17 wt%, or 5 wt% to 15 wt%. When included in the above ranges, there is an advantage in that the inorganic particles can excellently perform the function of removing moisture or hydrofluoric acid gas without hindering the flexibility of the lead film. Furthermore, when the inorganic particles are included in one or more of the three layers of the lead film, the inorganic particles may be included in an amount of 5 wt% to 15 wt%, preferably 6 wt% or more, 7 wt% or more, for each layer, based on the total weight of the included layer, and may also be included in an amount of 14 wt% or less, 13 wt% or less. When included in this range, it may be preferable for the aforementioned performance improvement and maintenance.

[0106]

[0107] Meanwhile, the pouch adhesive layer (1901) may be a layer that directly contacts the battery case (110), specifically, the sealant layer of the battery case (110). The pouch adhesive layer (1901) may include, but is not limited to, polypropylene or polyolefin elastomer (POE). Among them, the polymer included in the pouch adhesive layer (1901) may be a copolymer. The melting point of the pouch adhesive layer (1901) including the copolymer in the pouch adhesive layer (1901) can be controlled within the above numerical range, and has a melting point similar to that of the polymer in the sealant layer of the battery case (110), which is advantageous in securing the sealing processability. The thickness of the pouch adhesive layer (1901) may be 40 ㎛ to 100 ㎛, specifically, 40 ㎛ to 80 ㎛, and more specifically, 40 ㎛ to 60 ㎛. When the thickness of the pouch adhesive layer (1901) satisfies the above numerical range, there is an effect of securing a polymer (e.g., polypropylene) residual rate sufficient to secure strength when sealing between the electrode lead and the battery case (110).

[0108] The core layer (1902) may be a layer positioned at the center of the lead film (190). The core layer (1902) may include, but is not limited to, polypropylene, polyolefin elastomer (POE), and / or additives such as colorants. Among them, the polymer included in the core layer (1902) may be a homopolymer. When the core layer (1902) includes a homopolymer, the melting point of the core layer (1902) 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 (1902) may be 40 ㎛ to 70 ㎛, specifically 50 ㎛ to 70 ㎛, and more specifically 60 ㎛ to 70 ㎛. When the thickness of the core layer (1902) satisfies the above numerical range, it has a robust design effect in terms of securing insulation by preventing deformation due to heat applied during fusion and sealing.

[0109] The above lead adhesive layer (1903) 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 lead adhesive layer (1903) 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 lead adhesive layer (1903) 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 lead adhesive layer (1903) satisfies the above numerical range, there is an effect of preventing pinholes and leaks at the edge when the electrode lead and the lead film are fused together.

[0110]

[0111] (5) Gas-induced film

[0112] In one aspect, the gas induction film (200) is for discharging gas from the inside of the battery case (110) to the outside. As illustrated in FIG. 2, the gas induction film (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 film (200) is disposed, the electrode lead (180) and the lead film (190) do not directly contact each other, and in the area where the gas induction film (200) is not disposed, the electrode lead (180) and the lead film (190) may directly contact each other.

[0113] Hereinafter, the gas induction film (200) of the present invention will be described in more detail with reference to FIGS. 3 and 6. FIG. 3 illustrates a state before the interface between the lead film (190) and the gas induction film (200) of a pouch-type secondary battery is opened, and FIG. 6 illustrates a state after the interface between the lead film (190) and the gas induction film (200) is opened.

[0114] As illustrated in FIGS. 3 and 6, the interface between the gas induction film (200) and the lead film (190) is normally not open, and when the internal pressure increases due to gas generation or the like inside the battery case (110), the interface between the gas induction film (200) and the lead film (190) may be opened to form a gas discharge path (300). The gas inside the battery case (110) may move along the gas discharge path (300) and then pass through the lead film (190) to be discharged to the outside of the pouch. As a result, the internal pressure of the battery case (110) may be lowered, thereby preventing explosion or ignition of the battery case (110). At this time, the lead film (190) may include inorganic particles (191) to improve the gas discharge speed, effectively prevent moisture penetration, and prevent corrosion of the electrode lead by adsorbing hydrofluoric acid gas generated inside.

[0115]

[0116] Meanwhile, as shown in FIGS. 3 and 4, the gas induction film (200) of the present invention includes an adhesive resin layer (210) in contact with the electrode lead (180), and a permeable resin layer (220) disposed on the adhesive resin layer (210).

[0117] The adhesive resin layer (210) is in contact with the electrode lead (180) and may be used to adhere the gas induction film (200) to the electrode lead (180).

[0118]

[0119] In one aspect, as shown in FIGS. 3 and 7, the adhesive resin layer (210) of the gas induction film (200) may be formed to be longer in the outer direction of the battery case (110) than the permeable resin layer (220). In this case, when the adhesive resin layer (210) is formed to protrude further than one end of the permeable resin layer (220) in the outer direction of the battery case (110), the adhesive force between the electrode lead (180) and the gas induction film (200) is strong, so that an increase in internal pressure and a decrease in durability due to frequent opening of the lead film (190) and the gas induction film (200) can be prevented, and it is easy to secure the area of ​​the gas permeable portion (230) on the permeable resin layer (220), so that stable gas discharge can be possible.

[0120] Alternatively, as described above, as in FIG. 8, the lead film (190) may be arranged so that one end protruding outwardly from the battery case (110) protrudes further than one end of the gas induction film (200) protruding outwardly from the battery case (110) and comes into direct contact with the electrode lead (180), and as in FIG. 7, the adhesive resin layer (210) may be arranged so that one end protruding outwardly from the battery case (110) protrudes further than one end of the permeable resin layer (220) protruding outwardly from the battery case (110), but the lead film (190) may not come into direct contact with the electrode lead (180) but comes into direct contact with the adhesive resin layer (210).

[0121] In the case where the arrangement structure of the lead film (190), electrode lead (180) and gas induction film (200) is formed as in FIG. 3, FIG. 7 or FIG. 8, the lead film (190) is not arranged so that one end protrudes further outward from the battery case (110) than the permeable resin layer (220) of the gas induction film (200), but is arranged on the permeable resin layer (220) of the gas induction film (200), which may be advantageous in terms of securing durability and securing the area of ​​the permeable portion (230). However, although it may be arranged as in FIG. 3 most preferably, there is no disadvantage in performance in the structure of FIG. 7 or FIG. 8, and there may be some differences in design and process.

[0122]

[0123] 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 film (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 film (200) is prevented from being detached from the electrode lead (180) and pushed out of the pouch, or the electrolyte inside the pouch is prevented from leaking.

[0124] The adhesive resin layer (210) may include at least one of an acid-modified polyolefin and a silane-modified polyolefin.

[0125] 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 film (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.

[0126] 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.

[0127] 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).

[0128] 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 gas induction film (200) and the electrode lead (180) can be easily fused together by melting the adhesive resin layer (210) within a set production time (tact time).

[0129]

[0130] The permeable resin layer (220) may be a layer in contact with the lead film (190).

[0131] The permeable resin layer (220) may include at least one of polytetrafluoroethylene (PTFE) and polyimide (PI), but is not limited thereto. In particular, 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 (300) can be formed when the internal pressure of the case (110) increases.

[0132] 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 (300).

[0133]

[0134] Meanwhile, the ratio (D1 / D2) of the thickness (D1) of the adhesive resin layer to the thickness (D2) of the permeable resin layer 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 film (200) and the electrode lead (180).

[0135]

[0136] In one aspect, the gas discharge path (300) formed by the opening of the interface between the gas induction film (200) and the lead film (190) may include a gas permeable portion (230) formed on the outside of the sealing portion (151), and one or more gas paths (240) formed such that the gas permeable portion (230) and the inside of the battery case (110) are connected to each other via the sealing portion (151).

[0137] In addition, the gas induction film (200) may have at least one gas path (240), preferably at least two, and there is no limitation on the number thereof. However, considering the processability and ease of manufacturing the gas induction film, it may be preferable to form at least two gas paths (240).

[0138]

[0139] FIGS. 9 and 10 are top perspective views of an electrode lead (180) and a lead film (190) according to one embodiment, that is, a portion of box A in FIG. 2 when viewed from the direction B, with the terrace portion (150) of the battery case (110) omitted, and the sealing portion (151), which is a sealed portion, illustrated as an area. As described above, a gas induction film (200) is disposed on the electrode lead (180), which may be laminated in the order of an adhesive resin layer (210) and a permeable resin layer (220), and a lead film (190) may be disposed on the gas induction film (200), and the terrace portion (150) of the battery case (110) may be disposed on the lead film (190) to form a packaging structure, and a sealing portion (151) may be formed on the terrace portion (150) through sealing.

[0140] Referring to FIG. 9, the gas induction film (200) and the lead film (190) form a gas discharge path (300) by opening the interface when the internal pressure of the pouch-type secondary battery increases, and a gas permeable portion (230), which is a portion through which gas is permeable, is formed on the outside of the sealing portion (151), so that gas captured through the gas path (240) is discharged through the lead film (190), and the gas path (240) connects the inside of the battery case (110) from the permeable portion (230) via the sealing portion (151), thereby forming a path so that the gas can move to the gas permeable portion (230). The above gas path (240) can be formed in one, and in this case, it can have a “ㅜ” shape as in FIG. 9, and the gas path (240) can be formed in two, and in this case, it can have a “ㅠ” shape as in FIG. 10.

[0141] Here, the gas permeation portion (230) and the gas path (240) can be distinguished by a horizontal dividing line in the width direction of the electrode lead (180) formed at a point where the angle of the extension line of the gas path (240) changes with respect to the longitudinal straight line of the electrode lead (180) on the outside of the sealing portion (151) in the top perspective view of FIG. 9 or 10, and the inner region of the battery case (110) can be defined as the gas path (240), and the outer region can be defined as the gas permeation portion (230).

[0142] The above gas induction film has a gas emission coefficient (C) defined by the following equation 1 R ) can be 10 to 25 days.

[0143] [Formula 1]

[0144] C R = 2(S A / W L ) + W P

[0145] In the above equation 1, W P is the sum of the widths of one or more gas channels (mm), and W L is the width of the electrode lead (mm), and S A is the area of ​​the penetration section (mm) 2 )am.

[0146] The above gas discharge coefficient is a value designed by its dimensions regardless of the material of the gas induction film, and is characterized by taking into account the area of ​​the permeation portion, the width of the gas channel, and the width of the electrode lead as factors. The gas discharge rate is advantageous when the area of ​​the permeation portion and the width of the gas channel are large, but conversely, the larger the area, the higher the possibility of problems occurring in terms of preventing moisture infiltration and electrolyte leakage. In addition, when the area of ​​the permeation portion of the gas induction film increases relative to the width of the electrode lead, the increase in gas discharge performance is not large compared to the increase in the area of ​​the permeation portion, which may result in an inappropriate design when considering the possibility of moisture infiltration and electrolyte leakage. Furthermore, when the width of the gas channel increases relative to the area of ​​the permeation portion, the gas discharge rate increases and the operating pressure decreases, forming a complex relationship in which the problem of moisture infiltration occurs.

[0147] In other words, although the gas induction film has better performance as the area of ​​the gas permeable portion increases, under the limitations of the width of the electrode lead and the width of the gas path, the gas discharge performance, moisture infiltration prevention, and electrolyte leakage prevention effects can be improved only by expanding the area of ​​the permeable portion. Accordingly, the gas induction film according to one embodiment of the present invention has a gas discharge coefficient as expressed by Equation 1, and is characterized in that it has a fast gas discharge rate, can prevent electrolyte leakage and moisture infiltration, and can be operated at a low internal pressure.

[0148] Preferably, the gas emission coefficient may be 11 or more, 12 or more, 13 or more, or 14 or more, and may also be 24 or less, 23 or less, 22 or less, or 21 or less. When the gas emission coefficient satisfies the above-mentioned range, a gas induction film that can satisfy moisture penetration prevention performance and electrolyte leakage prevention performance together with gas emission performance can be implemented.

[0149] In one aspect, the gas induction film has a width (W) of the electrode lead L) for the area of ​​the permeable portion (S) A ) of the ratio (S) A / W L ) may be 1.7 mm to 7.5 mm, preferably 1.9 mm or more, 2.2 mm or more, 2.5 mm or more, or 2.7 mm or more, and also preferably 7.0 mm or less, 6.5 mm or less, 6.0 mm or less, 5.5 mm or less, or 5.0 mm or less.

[0150] In one aspect, the gas induction film is the sum of the widths of the gas paths (W P ) may be 6 mm to 20 mm. Preferably, it may be 7 mm or more, 8 mm or more, 9 mm or more, or 10 mm or more, and 18 mm or less, 16 mm or less, 15 mm or less, or 14 mm or less.

[0151] In one aspect, the gas emission coefficient of the above gas induction film is “the width of the electrode lead (W L ) for the area of ​​the permeable portion (S) A ) of the ratio (S) A / W L ) and “the sum of the widths of the gas euros (W P )” can mean the sum of the gas permeable area and the width of the gas path for the electrode lead width. That is, when the total sum of the gas permeable area and the width of the gas path has a mutually appropriate value, that is, when it is maintained in an appropriate range so as to complement each other, it can be advantageous in terms of gas discharge performance, moisture penetration, and prevention of electrolyte leakage.

[0152] Moreover, as batteries become larger and are designed in modules and packs, there may be various variables such as the battery cell itself becoming larger or multiple small battery cells being assembled, but in the case of the above gas emission coefficient, by reflecting the size of the battery cell through the width of the electrode lead, it is possible to determine an appropriate design point in the three-way trade-off relationship among the gas emission rate, moisture infiltration amount, and operating pressure depending on the amount of gas generated.

[0153] Accordingly, the pouch-type secondary battery described in this specification has the gas-inducing film as described above, but includes inorganic particles in the gas-permeable lead film, thereby being capable of discharging gas at a significantly higher rate at a low operating pressure, and also has excellent performance in preventing electrolyte leakage and moisture infiltration, and is provided with a means for minimizing corrosion problems caused by the generated gas or corrosion caused by moisture infiltration or electrolyte leakage, thereby contributing to an improvement in lifespan by increasing durability, and has the advantage of being able to maintain the operating performance of the cell by continuous gas discharge, and also ensuring safety by reducing the risk of explosion due to swelling.

[0154]

[0155] (6) Electrolyte

[0156] In one aspect, the pouch-type secondary battery (100) may further include an electrolyte (not shown) injected into the 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, an oxide type, or a polymer type, and such a solid electrolyte may have flexibility that is easily deformed by an external force.

[0157]

[0158] battery box

[0159] In one aspect, a battery box including the pouch-type secondary battery is provided. The battery box may include the pouch-type secondary battery and a packaging housing 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 one embodiment of the present specification described above.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164]

[0165] electrical devices

[0166] In one aspect, an electrical device including the battery box is provided. The battery box can be included in the electrical device and can be used as a power source for the electrical device.

[0167] The above electric device may be, for example, one or more medium- to large-sized devices, such as a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0168]

[0169] 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.

[0170]

[0171] Examples and Comparative Examples

[0172] Example 1

[0173] (1) Manufacturing of battery case

[0174] 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.

[0175] 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.

[0176] A battery case including a receiving portion and a sealing portion was manufactured by molding the above pouch film laminate.

[0177]

[0178] (2) Manufacturing of pouch-type secondary batteries

[0179] 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.

[0180] 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 battery case with the tips of the electrode leads extended outward, and the electrolyte was poured.

[0181] A 40 ㎛ thick acid-modified polypropylene film (adhesive resin layer) and a 50 ㎛ thick polytetrafluoroethylene film (permeable resin layer) were sequentially laminated on the upper surface of the electrode lead to form a gas induction film.

[0182] 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 film, respectively. The lead film includes a 75 μm thick lead 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. The core layer contained 8 wt% of inorganic particles of CaCO3 based on the total weight of the core layer, thereby preparing the lead film.

[0183] Afterwards, the sealing part of the battery case 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 of the terrace part where the gas induction film is formed has a structure in which a lower case / lead film / electrode lead / gas induction film / lead film / upper case are sequentially laminated.

[0184]

[0185] Example 2

[0186] A pouch-type secondary battery was manufactured in the same manner as Example 1, except that 8 wt% of CaCO3 was included as inorganic particles in each core layer and lead adhesive layer of the lead film, based on the total weight of each layer.

[0187]

[0188] Comparative Example 1

[0189] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a lead film containing no inorganic particles was applied.

[0190]

[0191] Experimental Example 1: Measurement of gas emission rate

[0192] The gas emission rate was measured for the pouch-type secondary batteries manufactured in Examples 1 and 2 and Comparative Example 1, respectively.

[0193] 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 2.0 atm, and the amount of gas emitted every 24 hours for 72 hours was measured, and the results are shown in Table 1 below.

[0194] Gas discharge rate @1.5 atm(cc / day)Gas discharge rate @2.0 atm(cc / day)Day 1Day 2Day 3AverageDay 1Day 2AverageExample 19.28.79.99.316.816.816.8Example 210.510.911.110.817.317.917.6Comparative example 17.18.97.37.813.712.213.0

[0195] Referring to Table 1 above, it can be confirmed that in Examples 1 and 2 including inorganic particles, the gas discharge rate is significantly improved compared to Comparative Example 1. In particular, it can be confirmed that the difference is more noticeable when the internal pressure is high, so it can be confirmed that it can be more suitably applied to cells with a large amount of gas generation, and even in other cases, it can make a significant contribution to ensuring safety.

[0196]

[0197] Experimental Example 2: Measurement of moisture penetration (HF concentration measurement)

[0198] In order to evaluate the moisture penetration amount of the pouch-type secondary batteries manufactured in Examples 1 and 2 and Comparative Example 1, the HF concentration was measured.

[0199] The moisture penetration amount was evaluated by leaving the pouch-type secondary battery under conditions of 60°C and 90% relative humidity for 16 weeks, then opening the secondary battery and measuring the concentration of HF in the electrolyte. The results are shown in Table 2 below.

[0200] HF concentration 2 weeks 8 weeks 16 weeks Example 1431.823464201 Example 2425.223324177 Comparative example 1444.424534212

[0201] Referring to Table 2 above, it can be confirmed that in the case of Examples 1 and 2, the amount of moisture penetration is reduced compared to Comparative Example 1, and the difference in the effect is not large, but in general, when designing in the direction of increasing the speed or amount of gas discharge, the problem of increased moisture penetration has always accompanied, but in the case of Examples 1 and 2, although the gas discharge performance was improved compared to Comparative Example 1, the amount of moisture penetration did not increase simultaneously, and it can be confirmed that in the case of the pouch-type secondary battery according to one embodiment of the present invention, the gas discharge performance can be improved without increasing the amount of moisture penetration.

[0202]

[0203] [Explanation of symbols]

[0204] 100: Pouch-type secondary battery

[0205] 110: Battery case

[0206] 120: Case 1

[0207] 122: Cup

[0208] 124: Reception area

[0209] 130: Case 2

[0210] 132: Cup

[0211] 140: Bridge section

[0212] 150: Terrace

[0213] 151: Sealing part

[0214] 160: Electrode assembly

[0215] 170: Electrode tab

[0216] 172: Positive tab

[0217] 174: Negative tab

[0218] 180: Electrode lead

[0219] 182: Positive lead

[0220] 184: Negative lead

[0221] 190: Lead Film

[0222] 191: Weapon particles

[0223] 1901: Pouch adhesive layer

[0224] 1902: Core layer

[0225] 1903: Lead adhesive layer

[0226] 200: Gas-induced film

[0227] 210: Adhesive resin layer

[0228] 220: Permeable resin layer

[0229] 230: Transmission section

[0230] 240: Gas Euro

[0231] 300: Gas discharge path

Claims

1. Electrode assembly; A battery case including a receiving portion for receiving the electrode assembly and a terrace portion formed along the periphery of the receiving portion; An electrode lead connected to the electrode assembly and protruding to the outside of the battery case via the terrace portion; A lead film disposed between the electrode lead and the battery case; and A gas induction film disposed between the electrode lead and the lead film; The above terrace portion includes a sealing portion that is partially sealed along the perimeter of the receiving portion, A pouch-type secondary battery, wherein the lead film comprises inorganic particles.

2. In paragraph 1, The above pouch-type secondary battery is a pouch-type secondary battery in which, when the internal pressure of the battery case increases, the interface between the lead film and the gas induction film opens to form a gas discharge path.

3. In paragraph 2, A pouch-type secondary battery, wherein the gas discharge path comprises a gas permeable portion formed on the outside of the sealing portion, and at least one gas path formed through the sealing portion so that the gas permeable portion and the inside of the battery case are connected to each other.

4. In paragraph 1, A pouch-type secondary battery, wherein the lead film has a structure in which a pouch adhesive layer, a core layer, and a lead adhesive layer are sequentially laminated, and the inorganic particles are included in at least one layer selected from the group consisting of the core layer and the lead adhesive layer.

5. In paragraph 1, A pouch-type secondary battery, wherein the lead film has a structure in which a pouch adhesive layer, a core layer, and a lead adhesive layer are sequentially laminated, and the inorganic particles are included in the core layer.

6. In paragraph 5, A pouch-type secondary battery, wherein the above-mentioned inorganic particles are further included in the lead adhesive layer.

7. In paragraph 1, A pouch-type secondary battery, wherein the above-mentioned inorganic particles include at least one selected from the group consisting of CaCO3, Ca(OH)2, CaCl2, CaO, KOH, NaOH, and Na2CO3.

8. In paragraph 1, A pouch-type secondary battery, wherein the inorganic particles are included in an amount of 1 wt% to 20 wt% based on the total weight of the lead film.

9. In paragraph 1, A pouch-type secondary battery, wherein the lead film is positioned so that one end protruding toward the outside of the battery case protrudes further than one end of the gas induction film protruding toward the outside of the battery case and is in direct contact with the electrode lead.

10. In paragraph 1, The above gas induction film is 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.

11. In paragraph 10, A pouch-type secondary battery, wherein the adhesive resin layer comprises at least one selected from the group consisting of acid-modified polypropylene (PPa) and acid-modified polyethylene (Pea).

12. In paragraph 10, A pouch-type secondary battery, wherein the above-mentioned permeable resin layer comprises at least one selected from the group consisting of polyimide (PI) and polytetrafluoroethylene (PTFE).

13. In paragraph 10, A pouch-type secondary battery, wherein the ratio (D1 / D2) of the thickness (D1) of the adhesive resin layer to the thickness (D2) of the permeable resin layer is 0.4 to 2.

0.

14. In paragraph 10, A pouch-type secondary battery, wherein the adhesive resin layer has one end protruding toward the outside of the battery case more than the end of the transparent resin layer protruding toward the outside of the battery case.

15. A battery box comprising a pouch-type secondary battery according to paragraph 1; and packaging for accommodating the pouch-type secondary battery.

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