Pouch-type rechargeable battery

Abstract

The pouch-type secondary battery according to the present invention includes an electrode assembly, a pouch-type case including a housing for housing the electrode assembly and a terrace portion provided around the housing, the terrace portion having a sealed portion in which a part of its width is sealed, electrode leads connected to the electrode assembly and protruding to the outside of the pouch-type case via the terrace portion, a lead film disposed between the electrode leads and the pouch-type case, and a gas induction film disposed between the electrode leads and the lead film. The gas induction film also includes a permeable portion formed on the outside of the sealed portion and one or more gas passages formed so that the permeable portion and the inside of the pouch-type case are connected to each other via the sealed portion, and the gas emission coefficient (C R ) is characterized by being between 10 and 25.

Description

[Technical Field]

[0001] The present invention relates to a pouch-type rechargeable battery, and more particularly to a pouch-type rechargeable battery including a gas induction film. [Background technology]

[0002] Rechargeable batteries are used in a wide range of applications, from small products such as digital cameras, DVD players, MP3 players, mobile phones, PDAs, portable game devices, power tools, and e-bikes, to large products requiring high output, such as electric vehicles and hybrid vehicles, as well as power storage devices and backup power storage devices that store surplus generated electricity and new / renewable energy. Types of rechargeable batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries.

[0003] Secondary batteries can be manufactured by housing an electrode assembly, in which positive electrodes, negative electrodes, and a separator membrane interposed between them are alternately stacked, in a battery case, injecting an electrolyte, and then sealing the battery case. Secondary batteries are classified into pouch type and can type, etc., depending on the material of the case that houses the electrode assembly. Among these, pouch type batteries can be manufactured by press-forming a flexible pouch film laminate to form a cup portion, then housing the electrode assembly in the housing space inside the cup portion, and sealing the seal portion.

[0004] Pouch-type rechargeable batteries can generate gas inside the pouch during high-temperature operation, overcharging, or short-circuiting. A problem arose where high gas pressure inside the pouch could cause the pouch to vent, leading to explosion or fire.

[0005] Therefore, research is being conducted on various forms of gas exhaust components to solve the above-mentioned problems. Currently, there is an increasing need for gas exhaust components that simultaneously address the issues of gas discharge, moisture infiltration from the outside, and electrolyte leakage, as well as gas exhaust components that can withstand high internal pressures while operating at low pressures, and gas exhaust components with superior durability. [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention aims to solve the above-mentioned problems and provides a pouch-type secondary battery that can operate at low internal pressure and has a fast gas discharge rate, while minimizing moisture penetration and electrolyte leakage through the design of the gas induction film. [Means for solving the problem]

[0007] [1] According to one embodiment, the invention includes an electrode assembly, a pouch-type case including a housing for housing the electrode assembly and a terrace portion provided around the housing, the terrace portion having a sealed portion having a portion of its width sealed, an electrode lead connected to the electrode assembly and protruding to the outside of the pouch-type case via the terrace portion, a lead film disposed between the electrode lead and the pouch-type case, and a gas induction film disposed between the electrode lead and the lead film, wherein the gas induction film includes a permeable portion formed on the outside of the sealed portion and one or more gas passages formed so that the permeable portion and the inside of the pouch-type case are connected to each other via the sealed portion, and the gas emission coefficient (C) is represented by the following formula 1. R A pouch-type rechargeable battery is provided, with a value of 10 to 25.

[0008]

number

[0009] In the above formula 1, W P is the sum of the widths of one or more gas flow paths (mm), W Lis the width (mm) of the electrode lead, and S A is the area (mm 2 ) of the permeable portion.

[0010] [2] In the above [1], when the internal pressure of the pouch-type secondary battery increases, the interface between the lead film and the gas guide film may be opened, and a gas discharge path may be formed along the gas flow path.

[0011] [3] In the above [1] and / or [2], the ratio (S L ) of the area of the permeable portion to the width (W A ) of the electrode lead (S A / W L ) may be 1.7 mm to 7.5 mm.

[0012] [4] In at least one of the above [1] to [3], the total width (W P ) of the gas flow path may be 6 mm to 20 mm.

[0013] [5] In at least one of the above [1] to [4], the gas guide 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.

[0014] [6] In the above [5], the adhesive resin layer may contain one or more selected from the group consisting of acid-modified polypropylene (PPa) and acid-modified polyethylene (Pea).

[0015] [7] In the above [5] and / or [6], the permeable resin layer may contain one or more selected from the group consisting of polyimide (PI) and polytetrafluoroethylene (PTFE).

[0016] [8] In at least one of the above [5] to [7], the ratio (D1 / D2) of the thickness of the adhesive resin layer (D1) to the thickness of the permeable resin layer (D2) may be 0.4 to 2.0.

[0017] [9] In at least one of the above [5] to [8], the thickness of the adhesive resin layer may be 5 μm to 130 μm.

[0018]

[10] In at least one of the above [5] to [9], the thickness of the permeable resin layer may be 40 μm to 100 μm.

[0019]

[11] In at least one of the above [5] to

[10] , the adhesive resin layer of the gas induction film may have one end that protrudes outward from the pouch-type case and protrudes further than the one end of the permeable resin layer of the gas induction film that protrudes outward from the pouch-type case.

[0020]

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

[11] , the gas flow path may be two or more.

[0021]

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

[12] , the lead film may be arranged such that one end protruding outward from the pouch-type case protrudes further than one end of the gas induction film protruding outward from the pouch-type case, and is in direct contact with the electrode lead.

[0022]

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

[13] , one surface of the electrode lead may be coated with one or more selected from the group consisting of chromium (Cr), nickel (Ni), aluminum oxide (Al2O3), zirconium (Zr)-based anhydrous oxide salts and titanium (Ti)-based anhydrous oxide salts. [Effects of the Invention]

[0023] The pouch-type secondary battery according to the present invention has the advantage of a fast gas discharge rate even with a low operating pressure at which gas discharge begins in the gas induction film, due to the dimensional design of the gas flow path and permeable portion constituting the gas induction film. Furthermore, while the problems of moisture penetration and electrolyte leakage through the gas induction film tend to be highly dependent on the material, these can be minimized through dimensional design, greatly contributing to overcoming the limitations of the material.

[0024] Therefore, the pouch-type secondary battery of the present invention can immediately discharge gas to the outside as soon as it is generated, and minimize electrolyte leakage and moisture penetration, thus providing excellent durability and safety. [Brief explanation of the drawing]

[0025] The drawings attached to the specification illustrate preferred embodiments of the present invention and serve to further illustrate the technical concept of the present invention together with the content of the invention described above. Therefore, the present invention should not be construed as being limited solely to the matters described in such drawings.

[0026] [Figure 1] This is an exploded assembly diagram of a pouch-type secondary battery according to the present invention. [Figure 2] This is a cross-sectional view of a sealed pouch-type rechargeable battery. [Figure 3] This is an example of a cross-sectional view of a pouch-type rechargeable battery before the pouch-type case is lifted. [Figure 4] This is an example of a cross-sectional view of a pouch-type secondary battery when the pouch-type case is being lifted. [Figure 5] This is another example of a cross-sectional view of a pouch-type rechargeable battery before the pouch-type case is lifted. [Figure 6] This is yet another example of a cross-sectional view of a pouch-type rechargeable battery before the pouch-type case is lifted. [Figure 7] This is a top perspective view of a gas induction film with a single gas channel according to one embodiment of the present invention. [Figure 8] This is a top perspective view of a gas induction film with two gas channels according to one embodiment of the present invention. [Modes for carrying out the invention]

[0027] The advantages and features of the present invention, as well as methods for achieving them, will become apparent with reference to the embodiments described below in detail, along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and can be realized in a variety of different forms. These embodiments are provided merely to complete the disclosure of the present invention and to allow a person ordinary in the art to which the invention belongs to to fully understand the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals indicate the same components.

[0028] Unless otherwise defined, all terms used herein (including technical and scientific terms) will be used in a sense that is commonly understood by those with ordinary skill in the art to which this invention pertains. Furthermore, terms defined in commonly used dictionaries will not be interpreted ideally or excessively unless otherwise clearly defined.

[0029] The terms used herein are for illustrative purposes only and do not limit the invention. In this specification, singular terms include plural terms unless otherwise specified in the statement. The terms “comprises” and / or “comprising” as used herein do not exclude the presence or addition of one or more other components in addition to those mentioned.

[0030] In this specification, if a part is said to include a component, it means that, unless otherwise stated, it may include other components rather than excluding them.

[0031] In this specification, the term "A and / or B" means A, B, or A and B.

[0032] In this specification, "%" means weight percent unless otherwise explicitly indicated.

[0033] The pouch-type rechargeable battery described herein includes at least one of the technical configurations described below, and may include any combination of technically feasible configurations from the following technical configurations.

[0034] The pouch-type secondary battery according to the present invention includes an electrode assembly, a pouch-type case including a housing for housing the electrode assembly and a terrace portion provided around the housing for the housing, the terrace portion having a sealed portion in which a part of its width is sealed, electrode leads connected to the electrode assembly and protruding to the outside of the pouch-type case via the terrace portion, a lead film disposed between the electrode leads and the pouch-type case, and a gas induction film disposed between the electrode leads and the lead film, wherein the gas induction film includes a permeable portion formed on the outside of the sealed portion and one or more gas passages formed so that the permeable portion and the inside of the pouch-type case are connected to each other via the sealed portion, and the pouch-type secondary battery has a gas emission coefficient (C) represented by the following formula 1. R ) is between 10 and 25.

[0035]

number

[0036] In the above formula 1, W P is the sum of the widths of one or more gas flow paths (mm), W L This is the width of the electrode lead (mm), S A The area of ​​the transparent part (mm²) 2 )

[0037] Generally, the gas emission performance of a gas induction film is determined by the properties of the materials that make up the film. The moisture penetration prevention performance and electrolyte leakage prevention performance are determined in accordance with the material properties, and the gas permeability is also a physical property that differs depending on the material. Therefore, the materials that make up the gas induction film play an important role.

[0038] However, even though materials play an important role, there are clearly areas that are not determined by the materials, and there are factors that can improve gas emission performance independently of the materials. Focusing on this, the present invention defines a gas induction film that has excellent gas emission performance while also improving moisture penetration prevention performance and electrolyte leakage prevention performance by designing the area of ​​the gas permeable portion in the gas induction film and the width of the gas flow path formed from the inside of the pouch-type case to the gas permeable portion.

[0039] First, the components of the pouch-type secondary battery of the present invention will be described in more detail with reference to the drawings.

[0040] Figure 1 is an exploded assembly diagram of the pouch-type secondary battery 100 according to the present invention, and Figure 2 is a cross-sectional view of the sealed pouch-type secondary battery 100. In Figure 2, some components of the pouch-type secondary battery 100 are omitted for ease of understanding. As shown in Figures 1 and 2, the pouch-type secondary battery 100 of the present invention includes a pouch-type case 110, an electrode assembly 160, electrode leads 180, a lead film 190, and a gas induction film 200.

[0041] (1) Pouch-type case According to one embodiment of the present invention, the pouch-type case 110 can house the electrode assembly 160 inside. The pouch-type case 110 can be manufactured by molding a pouch film laminate. In this case, the pouch film laminate may include a base layer, a gas barrier layer, and a sealant layer. In the pouch film laminate, the base layer, gas barrier layer, and sealant layer may be laminated sequentially.

[0042] The base layer is formed on the outermost layer of the pouch film laminate to protect the secondary battery from friction and impact with the outside. The base layer is made of polymer and can electrically insulate the electrode assembly from the outside.

[0043] The base layer may consist 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, poly(p-phenylenebenzobisoxazole), polyarylate, Teflon, and glass fiber. Preferably, the base layer consists of polyethylene terephthalate (PET), nylon, or a combination thereof, which have abrasion resistance and heat resistance.

[0044] The substrate layer may have a single film structure consisting of any one of the following materials. Alternatively, the substrate layer may have a composite film structure formed by two or more materials, each forming a layer.

[0045] The thickness of the substrate layer may be 5 μm to 50 μm, specifically 7 μm to 40 μm, or more specifically 25 μm to 38 μm. When the thickness of the substrate layer meets the above range, it exhibits excellent external insulation properties, and because the overall thickness of the pouch is not thick, it provides excellent volume-specific energy density for the secondary battery.

[0046] The gas barrier layer is laminated between the substrate layer and the sealant layer to ensure the mechanical strength of the pouch, block the entry and exit of gases and moisture from the outside of the secondary battery, and prevent electrolyte leakage from inside the pouch-type case.

[0047] The gas barrier layer may be formed of a metal, and more specifically, of an aluminum alloy thin film. When an aluminum alloy thin film is used to form the gas barrier layer, it is possible to ensure mechanical strength above a predetermined level, while keeping the weight low and ensuring complementarity of electrochemical properties by the electrode assembly and electrolyte, as well as heat dissipation. The aluminum alloy thin film may contain one or more metallic elements other than aluminum (Al), such as iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0048] The thickness of the gas barrier layer may be 40 μm to 100 μm, specifically 50 μm to 90 μm, or more specifically 55 μm to 85 μm. When the thickness of the gas barrier layer meets the above range, the moldability during molding of the cup portion and the gas barrier performance are excellent.

[0049] The sealant layer is intended to completely seal the inside of the pouch-type case, which contains the electrode assembly, by heat-bonding it to itself at the sealing portion when the pouch-type case is sealed. For this purpose, the sealant layer may be formed from a material that has excellent heat-bonding strength.

[0050] The sealant layer may be formed from a material that has insulating, corrosion-resistant, and sealing properties. Specifically, since the sealant layer is in direct contact with the electrode assembly and / or electrolyte inside the pouch-type case, it may be formed from a material that has insulating and corrosion-resistant properties. Also, since the sealant layer must completely seal the inside of the pouch-type case and block the movement of material between the inside and outside, it may be formed from a material with high sealing properties (e.g., excellent thermal adhesion strength). To ensure such insulating, corrosion-resistant, and sealing properties, the sealant layer may be formed from a polymer material.

[0051] The sealant layer may consist of one or more substances selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyarylate, Teflon, and glass fibers, and is preferably composed of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may consist of unoriented polypropylene (Cast Polypropylene, CPP), acid-modified polypropylene (PPA), polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene ternary copolymer.

[0052] The thickness of the sealant layer may be 30 μm to 130 μm, specifically 50 μm to 120 μm, or more specifically 70 μm to 100 μm. When the thickness of the sealant layer is within the above range, it has the effect of ensuring the moldability of the pouch film laminate while ensuring the seal strength of the sealed portion.

[0053] On the other hand, the pouch film laminate may be drawn and stretched using a punch or the like for the manufacture of the pouch-type case 110. As a result, the pouch-type case 110 may include a cup portion 122 and a storage portion 124. The storage portion 124 is a portion for housing the electrode assembly and can mean a storage space that is formed in a pocket shape inside the cup portion 122 when the cup portion 122 is formed.

[0054] According to one embodiment of the present invention, the pouch-type case 110 may include a first case 120 and a second case 130, as shown in Figure 1. The first case 120 includes a housing section 124 capable of housing an electrode assembly 160, and the second case 130 may cover the housing section 124 from above to prevent the electrode assembly 160 from detaching from the battery case 110. The first case 120 and the second case 130 may be manufactured with one side connected to the other, as shown in Figure 1, but are not limited to this, and can be manufactured in various ways, such as being manufactured separately from each other.

[0055] According to another embodiment of the present invention, when forming cup portions in a pouch film laminate, drawing-molding may be performed so that two symmetrical cup portions 122 and 132 are adjacent to each other in one pouch film laminate. In that case, cup portions 122 and 132 can be formed in the first case 120 and the second case 130, respectively, as shown in Figure 1. The electrode assembly 160 is housed in the housing portion 124 provided in the cup portion 122 of the first case 120, and then the bridge portion 140 formed between the two cup portions 122 and 132 is folded so that the two cup portions 122 and 132 face each other. In that case, the cup portion 132 of the second case 130 can house the electrode assembly 160 from above. Therefore, since two cup portions 122 and 132 house one electrode assembly 160, a thicker electrode assembly 160 can be housed than when there is only one cup portion 122. Furthermore, since one edge of the secondary battery 100 is formed when the pouch-type case 110 is folded, the number of edges to be sealed during the subsequent sealing process can be reduced. This improves the process speed of the pouch-type secondary battery 100 and reduces the number of sealing steps.

[0056] The pouch-type case 110 may be sealed with the electrode assembly 160 housed inside such that a portion of the electrode lead 180, i.e., the 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 is housed in a housing portion 124 provided in the cup portion 122 of the first case 120, and the housing portion 124 may be covered from above by the second case 130. Next, an electrolyte is injected into the housing portion 124, and a portion of the terrace portion 150 formed on the edges along the perimeter of the first case 120 and the second case 130 may be sealed to form a sealed portion (not shown).

[0057] The sealing portion serves to seal the housing portion 124. Specifically, the sealing portion may be formed on a terrace portion 150 formed on the edge along the perimeter of the housing portion 124 to seal the housing portion 124.

[0058] The sealing temperature of the seal portion may be 180°C to 250°C, specifically 200°C to 250°C, or more specifically 210°C to 240°C. When the sealing temperature meets the above numerical range, the pouch-type case 110 can achieve sufficient seal strength through heat bonding.

[0059] (2) Electrode assembly According to one embodiment of the present invention, the electrode assembly 160 may be inserted into a pouch-type case 110, injected with an electrolyte, and then sealed by the pouch-type case 110.

[0060] The electrode assembly 160 may be formed by sequentially stacking a positive electrode, a separator membrane, and a negative electrode. Specifically, the electrode assembly 160 may include two types of electrodes, a positive electrode and a negative electrode, and a separator membrane interposed between the electrodes to insulate them from each other.

[0061] The positive and negative electrodes may each have a structure in which an active material slurry is coated onto a metal foil or metal mesh electrode current collector containing aluminum and copper, respectively. The slurry may typically be formed by stirring granular active material, auxiliary conductors, binders, conductive materials, etc., with a solvent added. The solvent may be removed in a subsequent step.

[0062] An electrode assembly 160 can be manufactured in a predetermined shape by applying a slurry of electrode active material and binder and / or conductive material to a positive electrode current collector and a negative electrode current collector, and then stacking them on both sides of a separator. The types of electrode assemblies 160 include, but are not limited to, stack type, jelly roll type, and stack-and-fold type.

[0063] The electrode assembly 160 may include an electrode tab 170.

[0064] The electrode tabs 170 are connected to the positive and negative electrodes of the electrode assembly 160, respectively, and protrude outward from the electrode assembly 160, serving as pathways for electron movement between the inside and outside of the electrode assembly 160. The electrode current collector included in the electrode assembly 160 may consist of a portion coated with electrode active material and an end portion not coated with electrode active material, i.e., a plain portion. The electrode tabs 170 may be formed by cutting the plain portion, or by connecting another conductive member to the plain portion by ultrasonic welding or the like. As shown in Figure 1, the electrode tabs 170 may protrude in different directions from the electrode assembly 160, but are not limited to this, and can be formed to protrude in various directions, such as protruding parallel to the same direction from one side.

[0065] (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 may be connected to the electrode tab 170 of the electrode assembly 160 by spot welding or the like.

[0066] The electrode lead 180 may be connected to the electrode assembly 160 and protrude to the outside of the pouch-type case 110 via the sealing portion 150. Specifically, one end of the electrode lead 180 may be connected to the electrode assembly 160, specifically to the electrode tab 170, and the other end of the electrode lead 180 may protrude to the outside of the pouch-type case 110 via the terrace portion 150.

[0067] The electrode leads 180 may include a positive electrode lead 182, one end of which is connected to the positive electrode tab 172 and extends in the direction in which the positive electrode tab 172 protrudes, and a negative electrode lead 184, one end of which is connected to the negative electrode tab 174 and extends in the direction in which the negative electrode tab 174 protrudes. The other ends of both the positive electrode lead 182 and the negative electrode lead 184 may protrude outside the battery case 110. Thus, electricity generated inside the electrode assembly 160 can be supplied to the outside. Also, since the positive electrode tab 172 and the negative electrode tab 174 are formed to protrude in various directions, the positive electrode lead 182 and the negative electrode lead 184 can also extend in various directions. The positive electrode lead 182 and the negative electrode 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 current collector, and the negative electrode lead 184 may be made of the same copper (Cu) material as the negative electrode current collector or copper material coated with nickel (Ni). A portion of the electrode lead 180 protruding from the outside of the battery case 110 may serve as a terminal and be electrically connected to an external terminal.

[0068] 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 one or more selected from the group consisting of chromium (Cr), nickel (Ni), aluminum oxide (Al2O3), zirconium (Zr)-based anhydrous oxide salts, and titanium (Ti)-based anhydrous oxide salts. In this case, corrosion resistance to the electrolyte and adhesion to the lead film 190 and / or the gas induction film 200 can be ensured.

[0069] (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 through the electrode leads 180 to the battery case 110, thereby maintaining the seal of the battery case 110. For this purpose, the lead film 190 may be formed of a non-conductive material that does not conduct electricity well. Generally, the lead film 190 is often an insulating tape that is easy to attach to the electrode leads 180 and / or the gas induction film 200 and is relatively thin in thickness, but it is not limited to this, and any material that can insulate the electrode leads 180 may be used.

[0070] The lead film 190 may be positioned to surround the outer surfaces 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 on one side, with at least a portion of the electrode lead 180 and the gas induction film 200 being surrounded by the lead film 190. The lead film 190 is positioned within the sealing portion 150 where the first case 120 and the second case 130 of the pouch-type case 110 are heat-fused together, allowing the electrode lead 180 and the gas induction film 200 to be bonded to the battery case 110.

[0071] The lead film 190 may be placed between the electrode lead 180 and / or the gas induction film 200 and the pouch-type case 110. For example, as shown in Figure 2, the lower case 110, lead film 190, electrode lead 180, gas induction film 200, lead film 190, and upper case 110 may be arranged in a sequentially laminated state in the sealing portion 150 area.

[0072] On the other hand, the lead film 190 may include one or more layers. Specifically, the lead film 190 may include sequentially laminated metal adhesive layers, core layers, and pouch adhesive layers.

[0073] The metal adhesive layer may be in direct contact with the electrode lead 180 and be used to bond the lead film 190 to the electrode lead 180. The metal adhesive layer may contain any material that readily adheres to the electrode lead 180. Specifically, the metal adhesive layer may contain acid-modified polyolefin. For example, the metal adhesive layer may contain, but is not limited to, at least one of PPa (acid modified polypropylene), PEa (acid modified polyethylene), and plasma-treated PP (plasma-treated polypropylene). The thickness may be 50 μm to 80 μm, more specifically 50 μm to 75 μm, and more specifically 60 μm to 75 μm. When the thickness of the metal adhesive layer satisfies the above numerical range, it has the effect of preventing through-type pinholes and leaks at the edge when the electrode lead and lead film are fused together.

[0074] The core layer may be a layer located in the center of the lead film 190. The core layer may, but is not limited to, polypropylene, polyolefin elastomer (POE), and / or additives such as colorants. Among these, the polymer contained in the core layer may be a homopolymer. When the core layer contains 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 ensuring insulation. The thickness of the core layer may be 40 μm to 70 μm, specifically 50 μm to 70 μm, and more specifically 60 μm to 70 μm. When the thickness of the core layer satisfies the above numerical range, deformation due to heat applied during fusion and sealing is prevented, resulting in a robust design effect in terms of ensuring insulation.

[0075] The pouch adhesive layer may be a layer that is in direct contact with the battery case 110, specifically the sealant layer of the pouch film laminate. The pouch adhesive layer may contain, but is not limited to, polypropylene or polyolefin elastomer (POE). Among these, the polymer contained in the pouch adhesive layer may be a copolymer. When the pouch adhesive layer contains such a copolymer, the melting point of the pouch adhesive layer can be controlled to the above numerical range, and since it has a melting point similar to that of the polymer in the sealant layer of the pouch film laminate, it is advantageous for ensuring sealing processability. The thickness of the pouch adhesive layer may be 40 μm to 100 μm, specifically 40 μm to 80 μm, and more specifically 40 μm to 60 μm. When the thickness of the pouch adhesive layer satisfies the above numerical range, it has the effect of ensuring a sufficient remaining polymer (e.g., polypropylene) to secure strength when sealing the electrode lead and the pouch film laminate.

[0076] (5) Gas induction film According to one embodiment of the present invention, the gas induction film 200 is for discharging gas from the inside of the pouch-type case 110 to the outside. As shown in Figure 2, the gas induction film 200 of the present invention may be placed between the electrode lead 180 and the lead film 190. In that case, in the region between the electrode lead 180 and the lead film 190, the electrode lead 180 and the lead film 190 do not come into direct contact in the region where the gas induction film 200 is placed, while the electrode lead 180 and the lead film 190 may come into direct contact in the region where the gas induction film 200 is not placed.

[0077] The gas induction film 200 of the present invention will be described in more detail below with reference to Figures 3 and 4. Figure 3 is a cross-sectional view of the pouch-type secondary battery before the pouch-type case is lifted, and Figure 4 is a cross-sectional view of the pouch-type secondary battery when the pouch-type case is lifted.

[0078] As shown in Figures 3 and 4, the interface between the gas induction film 200 and the lead film 190 can remain closed and not open under typical driving conditions or when the amount of gas generated internally is small.

[0079] However, if gas is generated during the internal battery reaction for a predetermined reason, causing the internal pressure of the pouch-type case 110 to increase, the interface between the gas induction film 200 and the lead film 190 opens along the gas flow path 240 of the gas induction film 200, thereby forming a gas discharge path 300. The gas inside the pouch-type case 110 moves to the permeable section 230 via the gas discharge path 300 formed along the gas flow path 240, and is then discharged to the outside of the pouch by passing through the lead film 190. As a result, the internal pressure of the pouch-type case 110 is reduced, preventing explosion or ignition of the pouch-type case 110 and thus ensuring the safety of the secondary battery.

[0080] On the other hand, as shown in Figures 3 and 4, the gas induction film 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 disposed on the adhesive resin layer 210.

[0081] The adhesive resin layer 210 may be in contact with the electrode lead 180 and may be used to bond the gas induction film 200 to the electrode lead 180.

[0082] According to one embodiment of the present invention, as shown in Figure 3 or Figure 4, the adhesive resin layer 210 of the gas induction film 200 may be formed to be longer than the permeable resin layer 220 in the outward direction of the pouch-type case 110, and one end of the lead film 190 that protrudes outward from the pouch-type case 110 may protrude further outward from the adhesive resin layer 210 and be arranged to be in direct contact with the electrode lead 180. When the lead film 190 is formed to protrude further outward from one end of the gas induction film 200 in the outward direction of the pouch-type case 110 in this way, 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 a decrease in durability due to an increase in internal pressure can be prevented, the area of ​​the permeable portion 230 on the permeable resin layer 220 can be easily secured, and stable gas discharge is possible.

[0083] Alternatively, as shown in Figure 5, the lead film 190 may be positioned so that one end protruding outward from the pouch-type case 110 protrudes further than one end of the gas induction film 200 protruding outward from the pouch-type case 110 and is in direct contact with the electrode lead 180. Or, as shown in Figure 6, the adhesive resin layer 210 may be positioned so that one end protruding outward from the pouch-type case 110 protrudes further than one end of the permeable resin layer 220 protruding outward from the pouch-type case 110, and the lead film 190 does not directly contact the electrode lead 180 but is in contact with the adhesive resin layer 210.

[0084] When the arrangement of the lead film 190, electrode lead 180, and gas induction film 200 is formed as shown in Figures 3, 5, or 6, the lead film 190 is not positioned so that one end protrudes further outside the pouch-type case 110 than the gas induction film 200. This arrangement is advantageous in terms of ensuring durability and securing the area of ​​the permeable portion 230 compared to when the lead film 190 is positioned on the permeable resin layer 220 of the gas induction film 200. However, the arrangement as shown in Figure 3 is the most preferable. Nevertheless, there are no disadvantages in terms of performance in the structures shown in Figures 5 or 6, and there may be some differences in design and manufacturing processes.

[0085] The adhesive resin layer 210 may contain any material that readily adheres to the electrode leads 180. Specifically, the adhesive resin layer 210 may contain a modified polyolefin resin. When the adhesive resin layer 210 contains a modified polyolefin resin, the adhesive strength between the gas induction film 200 and the electrode leads 180 is improved, so even when the pouch-type secondary battery is stored in a high-temperature environment, it is possible to prevent the gas induction film 200 from detaching from the electrode leads 180 and being pushed to the outside of the pouch, or the electrolyte inside the pouch from leaking out.

[0086] The adhesive resin layer 210 may contain at least one of acid-modified polyolefins and silane-modified polyolefins.

[0087] Acid-modified polyolefin refers to a polyolefin resin that has been graft-modified with acid. For example, an acid-modified polyolefin may be a polyolefin resin that has been reacted with an unsaturated carboxylic acid to introduce a carboxyl group (graft modification). In this case, the unsaturated carboxylic acid may include the concept of a carboxylic acid anhydride, and the carboxyl group may include the concept of a carboxylic acid anhydride group. The unsaturated carboxylic acid to be reacted with the polyolefin resin may include, but is not limited to, one or more selected from the group consisting of maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, citraconic acid, aconitic acid, norbornenedicarboxylic acid anhydride, and tetrahydrophthalic acid anhydride. Among these, it is preferable to use maleic anhydride so that the adhesive strength between the gas induction film 200 and the electrode lead 180 can be improved. Acid-modified polyolefins may include, but are not limited to, one or more selected from the group consisting of PPa (acid-modified polypropylene) and PEa (acid-modified polyethylene).

[0088] Silane-modified polyolefin refers to a polyolefin resin that has been graft-modified with an unsaturated silane compound. A silane-modified polyolefin may have a structure in which an unsaturated silane compound is graft-copolymerized onto the main chain of the polyolefin resin. A silane-modified polyolefin resin may contain, 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.

[0089] The adhesive resin layer 210 may be modified, and examples of such modification treatments include ion implantation, plasma treatment, radiation irradiation, and heat treatment, with a preference for treatments that change the bonding structure of the polymer layer. These modification treatments can be carried out individually or in combination of two or more types. The modified adhesive resin layer 210 may, but is not limited to, plasma-treated polypropylene (PP).

[0090] The thickness of the adhesive resin layer 210 may be 5 μm to 130 μm, specifically 30 μm to 120 μm, or 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 melts within a specified tact time, allowing the gas induction film 200 and the electrode lead 180 to be easily fused together.

[0091] The permeable resin layer 220 may be a layer in contact with the lead film 190.

[0092] The permeable resin layer 220 may contain, but is not limited to, at least one of polytetrafluoroethylene (PTFE) and polyimide (PI). Among these, the case in which the permeable resin layer 220 contains polyimide is preferable because it reduces the adhesive strength between the permeable resin layer 220 and the lead film 190, and a gas discharge path 300 is formed when the internal pressure of the case 110 increases. The case in which polytetrafluoroethylene is contained is preferable because it has excellent gas permeability as well as excellent liquid barrier properties, which reduces the possibility of electrolyte seeping in through the gas discharge path when gas is not discharged, and the adhesive strength with the lead film 190 is weak, allowing the operating pressure to be lowered and gas discharge to be started earlier.

[0093] The thickness of the permeable resin layer 220 may be 40 μm to 100 μm, specifically 40 μm to 90 μm, or more specifically 45 μm to 75 μm. When the thickness of the permeable resin layer 220 satisfies the above numerical range, the permeable resin layer 220 does 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 is lifted, forming a gas discharge path 300.

[0094] On the other hand, the ratio (D1 / D2) of the thickness of the adhesive resin layer (D1) to the thickness of the permeable resin layer (D2) may be 0.4 to 2.0, more specifically 0.4 to 1.5, or more specifically 0.4 to 1.0. When the ratio (D1 / D2) satisfies the above numerical range, the interface between the permeable resin layer 220 and the lead film 190 is lifted when the internal pressure of the case 110 increases, forming a gas discharge path, while the adhesive strength between the gas induction film 200 and the electrode lead 180 can be improved.

[0095] According to one embodiment of the present invention, the gas induction film 200 includes a permeable portion 230 formed on the outside of the sealing portion, and one or more gas flow paths 240 formed such that the permeable portion and the inside of the pouch-type case are connected to each other via the sealing portion.

[0096] Furthermore, the gas induction film 200 has one or more gas flow channels 240, preferably two or more. There are no restrictions on the number of gas flow channels as long as the gas emission coefficient described later is satisfied. However, considering ease of process and the ease of manufacturing the gas induction film, it is preferable that two gas flow channels 240 are formed.

[0097] Figures 7 and 8 are top perspective views of the gas induction film 200 on the electrode lead 180 and lead film 190 portion according to one embodiment of the present invention, in which the terrace portion 150 of the pouch-type case 110 is omitted, and the sealed portion 151 is shown as a region. As described above, the gas induction film 200 is placed on the electrode lead 180, but it may also be laminated in the order of adhesive resin layer 210 and permeable resin layer 220, and the lead film 190 may be placed on the gas induction film 200, and the terrace portion 150 of the pouch-type case 110 may be placed on the lead film 190 for packaging, and a sealed portion 151 may be formed on the terrace portion 150 by sealing.

[0098] Referring to Figure 7, the gas induction film 200 has a permeable portion 230, which is the part through which gas passes, formed outside the sealing portion 151, and the gas flow path 240 forms a path through which gas is discharged, connecting the permeable portion 230, the sealing portion 151, and the inside of the pouch-type case 110. The gas induction film 200 may have one gas flow path 240, which may have a "┬" shape as shown in Figure 7, or it may have two gas flow paths 240, which may have a "Π" shape as shown in Figure 8. When there are two or more gas flow paths 240 as shown in Figure 6, the width (W) of the multiple gas flow paths 240 is P1 , W P2 , W P3 ···W Pn The sum of ) is used as a factor in the gas emission coefficient in the following equation 1. P (WP=W P1 +W P2 +W P3 +···+W Pn ) is also acceptable.

[0099] Here, the permeable portion 230 and the gas flow path 240 are separated by a dividing line horizontal to the width direction of the electrode lead 180, formed at a point on the top perspective view of the gas induction film 200 as shown in Figure 7 or Figure 8, outside the seal portion 151, where the angle of the extension line of the gas flow path 240 changes with respect to the straight line in the longitudinal direction of the electrode lead 180. The area on the inside of the pouch-type case 110 can be defined as the gas flow path 240, and the area on the outside as the permeable portion 230.

[0100] The aforementioned pouch-type secondary battery has a gas emission coefficient (C) defined by the following formula 1. R ) is between 10 and 25.

[0101]

number

[0102] In the above formula 1, W P is the sum of the widths of one or more gas flow paths (mm), W L This is the width of the electrode lead (mm), S A The area of ​​the transparent part (mm²) 2 )

[0103] In the following explanation of gas emission coefficients, the reference numerals for each component in the drawings will be omitted.

[0104] The aforementioned gas emission coefficient is a value designed based on the dimensions of the gas induction film, independent of the material of the film, and is characterized by having the area of ​​the permeate, the width of the gas flow path, and the width of the electrode lead as factors. The gas emission rate is advantageous as the area of ​​the permeate and the width of the gas flow path increase, but conversely, the larger these factors are, the higher the likelihood of problems arising in terms of preventing moisture penetration and electrolyte leakage. Furthermore, if the area of ​​the permeate of the gas induction film is larger than the width of the electrode lead, the improvement in gas emission performance is not large compared to the increase in the area of ​​the permeate, which may result in an inappropriate design considering the possibility of moisture penetration and electrolyte leakage. Moreover, if the width of the gas flow path is larger than the area of ​​the permeate, the gas emission rate increases and the operating pressure decreases, but the problem of moisture penetration arises, forming a complex relationship.

[0105] In other words, while a gas induction film exhibits superior performance with a larger permeable area, the gas discharge performance, moisture penetration prevention effect, and electrolyte leakage prevention effect cannot be improved without expanding the permeable area under the limitations of the electrode lead width and gas flow path width. Accordingly, a gas induction film according to one embodiment of the present invention has a gas discharge coefficient as shown in Formula 1 above, and is characterized by a fast gas discharge rate, the ability to prevent electrolyte leakage and moisture penetration, and the ability to operate at low internal pressure.

[0106] The gas emission coefficient is preferably 11 or more, 12 or more, 13 or more, or 14 or more, and also preferably 24 or less, 23 or less, 22 or less, or 21 or less. When the gas emission coefficient satisfies the above range, a gas induction film that satisfies not only gas emission performance but also moisture penetration prevention performance and electrolyte leakage prevention performance can be realized.

[0107] More specifically, a gas induction film according to one embodiment of the present invention has an electrode lead width (W L Area of ​​the transparent part (S) relative to ) A ) ratio (S A / W LThe diameter may be between 1.7 mm and 7.5 mm, but is preferably 1.9 mm or more, 2.2 mm or more, 2.5 mm or more, or 2.7 mm or more, and is 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.

[0108] Furthermore, the gas induction film according to one embodiment of the present invention has a total width (W) of the gas flow path. P The diameter may be 6mm to 20mm. It is preferably 7mm or more, 8mm or more, 9mm or more, or 10mm or more, and 18mm or less, 16mm or less, 15mm or less, or 14mm or less.

[0109] The gas emission coefficient of a gas induction film according to one embodiment of the present invention is "the width of the electrode lead (W L Area of ​​the transparent part (S) relative to ) A ) ratio (S A / W L ) and "the sum of the widths of the gas flow paths (W P This means the sum of the area of ​​the permeable portion and the width of the gas flow path relative to the width of the electrode lead. In other words, when the sum of the area of ​​the permeable portion and the width of the gas flow path relative to the width of the electrode lead has an appropriate value for each other, that is, when an appropriate range is maintained so that they complement each other, it is advantageous for gas discharge performance, prevention of moisture penetration and electrolyte leakage. If the area of ​​the permeable portion and the width of the gas flow path are both too small relative to the width of the electrode lead, the gas discharge coefficient will be small, less than 10, and as a result, an effect above a certain level can be achieved in terms of moisture penetration and electrolyte leakage, but naturally, the operating pressure will be too high and the gas discharge rate will be slow, so gas discharge will not be smooth, and as a result, problems due to cell swelling may occur.

[0110] Conversely, if both the permeable area relative to the electrode lead width and the gas channel width increase simultaneously, the gas emission coefficient may exceed 25. In this case, the problems of moisture penetration and electrolyte leakage become serious, making it difficult to apply as a gas induction film for cells. Furthermore, if the permeable area relative to the electrode lead width is somewhat small, the gas induction film can be designed by utilizing the gas emission coefficient, for example, by designing a relatively wide gas channel width, or by designing a wide permeable area relative to the electrode lead width even if the gas channel width is narrow.

[0111] Furthermore, as batteries become larger and are designed in module and pack units, various modifications can occur, such as the battery cells themselves becoming larger or multiple small battery cells being assembled. However, in the case of the gas emission coefficient, by reflecting the size of the battery cell using the width of the electrode leads, it is possible to grasp the appropriate design point in the trade-off relationship between the gas emission rate, moisture infiltration rate, and operating pressure, depending on the amount of gas generated.

[0112] As a result, the pouch-type secondary battery according to one embodiment of the present invention, by incorporating the aforementioned gas induction film, can discharge gas at a high speed with low operating pressure, has excellent performance in preventing electrolyte leakage and moisture penetration, and since there are no problems with corrosion caused by the generated gas or corrosion caused by moisture penetration or electrolyte leakage, it can contribute to an improved lifespan by increasing durability, can maintain the driving performance of the cell by continuously discharging gas, and can also ensure safety by reducing the risk of explosion due to swelling.

[0113] (6) Electrolyte The pouch-type secondary battery 100 according to the present invention may further include an electrolyte (not shown) that is injected into the inside of the pouch-type case 110. The electrolyte is for moving lithium ions generated by the electrochemical reaction of electrodes during charging / discharging of the secondary battery 100, and may include a non-aqueous organic electrolyte which is a mixture of lithium salt and organic solvents, or a polymer using a polymer electrolyte. The electrolyte may also include a sulfide-based, oxide-based, or polymer-based solid electrolyte, and such a solid electrolyte may have flexibility that makes it easily deformable by external force. [Examples]

[0114] The present invention will be described in more detail below with reference to specific examples. However, the following examples are merely illustrative to aid in understanding the present invention and do not limit its scope. It will be obvious to those skilled in the art that various changes and modifications are possible within the scope of the description and the technical concept, and that such variations and modifications are included in the appended claims.

[0115] Examples and Comparative Examples Examples 1-7, Comparative Examples 1-6 (1) Manufacturing of pouch-type cases A pouch film laminate with a polyethylene terephthalate / nylon / aluminum alloy thin film / polypropylene film structure was manufactured by laminating a polyethylene terephthalate / nylon / aluminum alloy thin film / polypropylene film onto one side of an aluminum alloy thin film measuring 266 mm wide, 50 m long, and 60 μm thick, and a polyethylene terephthalate (PET) film measuring 266 mm wide, 50 m long, and 12 μm thick, and a nylon film measuring 266 mm wide, 50 m long, and 25 μm thick, and laminating a polypropylene film measuring 266 mm wide, 50 m long, and 80 μm thick onto the other side.

[0116] Here, the polyethylene terephthalate film and nylon film are the base layer, the aluminum alloy thin film is the gas barrier layer, and the polypropylene film is the sealant layer.

[0117] A pouch-type case including a storage section and a sealing section was manufactured by molding the aforementioned pouch film laminate.

[0118] (2) Manufacturing of pouch-type rechargeable batteries An electrode assembly was manufactured by stacking a negative electrode, a positive electrode, and a porous polyethylene separation membrane, and then laminating them. Next, electrode leads were attached to the electrode assembly.

[0119] An electrolyte was prepared by dissolving LiPF6 in a solvent (volume ratio of EC:EMC:DMC = 3:3:4) to a concentration of 1.0 M. The electrode assembly was placed in the pouch-type case with the tips of the electrode leads extended to the outside, and the electrolyte was poured in.

[0120] A gas induction film was formed by sequentially laminating a 40 μm thick acid-modified polypropylene film (adhesive resin layer) and a 50 μm thick polytetrafluoroethylene film (permeable resin layer) onto the upper surface of the electrode lead.

[0121] Next, a lead film with a thickness of 200 μm was laminated onto 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 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.

[0122] Subsequently, the sealing portion of the pouch-type case was sealed for 2 seconds under the conditions of a sealing bar area of ​​200 mm x 10 mm, 220°C, and 0.27 MPa, and then left at 60°C for 4 hours to manufacture the pouch-type secondary battery. In this case, the portion of the terrace where the gas induction film is formed has a structure in which the lower case / lead film / electrode lead / gas induction film / lead film / upper case are sequentially laminated.

[0123] Using the method described above, pouch-type secondary batteries of Examples 1-7 and Comparative Examples 1-6 were manufactured so that the gas induction film had the dimensions shown in Table 1 below.

[0124] [Table 1]

[0125] Experimental Example 1: Measurement of Gas Emission Rate The gas discharge rate was measured for the pouch-type secondary batteries manufactured in Examples 1-7 and Comparative Examples 1-6, respectively.

[0126] Specifically, CO2 was injected into the pouch-type secondary battery using an internal pressure device manufactured by ITS Corporation to increase the internal pressure of the pouch to 1.5 atm. The amount of gas discharged was then measured for 24 hours, and the results are shown in Table 2 below.

[0127] Experimental Example 2: Measurement of the operating pressure of a gas induction film The operating pressure of the gas induction film was measured for the pouch-type secondary batteries manufactured in Examples 1-7 and Comparative Examples 1-6, respectively.

[0128] Specifically, using an internal pressure device manufactured by ITS Corporation, CO2 was injected into the pouch-type secondary battery, and the internal pressure of the pouch was increased in increments of 0.1 atm while the battery was left for 24 hours at different pressure levels. The pressure at which the permeable portion of the gas induction film was completely deformed (when the entire permeable portion was lifted) was measured, and the results are shown in Table 2 below.

[0129] Experiment Example 3: Measurement of water infiltration (measurement of HF concentration) In the pouch-type secondary batteries manufactured in Examples 1-7 and Comparative Examples 1-6, the HF concentration was measured to evaluate the amount of moisture penetration.

[0130] The amount of moisture penetration was evaluated by leaving pouch-type secondary batteries at 60°C and 90% relative humidity for 16 weeks, then opening the batteries and measuring the HF concentration in the electrolyte. The results are shown in Table 2 below.

[0131] [Table 2]

[0132] Referring to Table 2 above, in Examples 1 to 7, which satisfy the gas emission coefficient, it can be confirmed that, although there are individual differences in the effects of the three types of effects—gas emission rate, operating pressure, and moisture penetration amount—none of them exhibit effects at a level that could be problematic. Specifically, in Examples 1 to 4, it can be confirmed that the gas emission rate was very fast and the HF concentration was at a negligible level. In Examples 5 to 7, the operating pressure was higher than in Examples 1 to 4, and the gas emission rate was relatively low, but the HF concentration was at a level of almost zero, so it can be confirmed that the moisture barrier effect was also excellent. However, in Comparative Examples 1, 4 to 6, because the gas emission coefficient was designed to be very small, the HF concentration was low, but the operating pressure was too high, and the gas emission rate was very slow in comparison, making it difficult to prevent the phenomenon of battery swelling. In Comparative Examples 2 and 3, it can be predicted that there is a problem in that the moisture penetration amount is too large, significantly increasing the possibility of side reactions occurring between battery operations. On the other hand, in the case of HF concentration, the permissible range may differ depending on the battery specifications. However, using the battery specifications evaluated in this experimental example as a standard, below 8,000 ppm, it is considered that while there is a possibility of slightly reducing the battery's durability, no side reactions significant enough to affect the cycle characteristics will occur. Below 4,000 ppm, it can be understood that there is no effect on the battery. Above 8,000 ppm, it can be evaluated that problems may arise such as a rapid deterioration of the durability of the seals and electrode leads due to battery corrosion, and accelerated capacity degradation due to the occurrence of side reactions. [Explanation of symbols]

[0133] 100 pouch-type rechargeable batteries 110 Pouch-type cases 120 Case 1 122 Cup section 124 Storage Unit 130 Case 2 132 Cup section 140 Bridge section 150 Terrace section 151 Seal part 160 Electrode assembly 170 Electrode Tabs 172 Positive Tab 174 Negative Electrode Tab 180 electrode leads 182 Positive lead 184 Negative lead 190 Lead Film 200 Gas Induction Film 210 Adhesive resin layer 220 Transparent resin layer 230 Transparent part 240 Gas flow path 300 Gas Emissions Pathways

Claims

1. Electrode assembly and A pouch-type case including a housing section for housing the electrode assembly, and a terrace section provided around the housing section, having a sealed section in which a portion of its width is sealed, An electrode lead connected to the electrode assembly and protruding to the outside of the pouch-type case via the terrace portion, A lead film is placed between the electrode lead and the pouch-type case, The electrode lead and the lead film are disposed between the electrode lead and the lead film, The gas induction film includes a permeable portion formed on the outside of the sealing portion, and one or more gas passages formed so as to connect the permeable portion and the inside of the pouch-type case via the sealing portion. The gas emission coefficient (C) is expressed by the following formula 1. Ｒ A pouch-type rechargeable battery with a value of 10 to 25. [Math 1] In the above formula 1, W Ｐ is the sum of the widths of one or more gas flow paths (mm), W Ｌ is the width of the electrode lead (mm), S Ａ The area of ​​the transparent part (mm²) ２ )

2. The pouch-type secondary battery according to claim 1, wherein when the internal pressure of the pouch-type case increases, the interface between the lead film and the gas induction film is opened, and a gas discharge path is formed along the gas flow path.

3. The gas guiding film has an area (S Ｌ ) of the permeation part with respect to the width (W Ａ ) of the electrode lead, and a ratio (S Ａ / W Ｌ ) of 1.7 mm to 7.5 mm. The pouch-type secondary battery according to claim 1.

4. The gas induction film has a total width (W) of the gas flow path. Ｐ A pouch-type secondary battery according to claim 1, wherein the diameter is 6 mm to 20 mm.

5. The pouch-type secondary battery according to claim 1, wherein the gas induction film has a structure in which an adhesive resin layer and a permeable resin layer are laminated from the upper surface of the electrode lead.

6. The pouch-type secondary battery according to claim 5, wherein the adhesive resin layer comprises one or more selected from the group consisting of acid-modified polypropylene (PPa) and acid-modified polyethylene (PEa).

7. The pouch-type secondary battery according to claim 5, wherein the permeable resin layer comprises one or more selected from the group consisting of polyimide (PI) and polytetrafluoroethylene (PTFE).

8. The pouch-type secondary battery according to claim 5, wherein the ratio (D1 / D2) of the thickness of the adhesive resin layer (D1) to the thickness of the permeable resin layer (D2) is 0.4 to 2.

0.

9. The pouch-type secondary battery according to claim 5, wherein the thickness of the adhesive resin layer is 5 μm to 130 μm.

10. The pouch-type secondary battery according to claim 5, wherein the thickness of the permeable resin layer is 40 μm to 100 μm.

11. The pouch-type secondary battery according to claim 5, wherein one end of the adhesive resin layer of the gas induction film protrudes outward from the pouch-type case, and this end protrudes further than the other end of the permeable resin layer of the gas induction film protruding outward from the pouch-type case.

12. The pouch-type secondary battery according to claim 1, wherein the gas flow path is two or more.

13. The pouch-type secondary battery according to claim 1, wherein one end of the lead film protruding outward from the pouch-type case protrudes further than one end of the gas induction film protruding outward from the pouch-type case.

14. One side of the electrode lead is made of chromium (Cr), nickel (Ni), and aluminum oxide (Al ２ O ３ The pouch-type secondary battery according to claim 1, which is coated with one or more selected from the group consisting of zirconium (Zr)-based anhydrous oxide salts and titanium (Ti)-based anhydrous oxide salts.

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