Pouch-type rechargeable battery

Abstract

The pouch-type secondary battery according to the present invention is characterized by comprising: an electrode assembly; an outer casing material including a housing portion for housing the electrode assembly and a terrace portion formed around the housing portion and having a sealed portion in which a part of its width is sealed; electrode leads electrically connected to the electrode assembly and protruding to the outside of the outer casing material; a lead film disposed between the electrode leads and the outer casing material; a gas induction portion disposed between the electrode leads and the lead film and including a permeable portion provided on the outside of the sealed portion and one or more gas flow channels extending from the permeable portion toward the electrode assembly via the sealed portion; and a reinforcing film disposed on the lead film such that at least a part of the permeable portion is covered. Furthermore, the reinforcing film includes an insertion portion occupying a part of the width of the sealed portion, and the insertion portion is characterized in that one end of the reinforcing film extends inward toward the outer casing material and is inserted between the outer casing material and the lead film of the sealed portion.

Description

Technical Field

[0001] This specification relates to a pouch-type secondary battery, and more particularly to a pouch-type secondary battery including a gas guiding portion for discharging internal gas.

Background Art

[0002] Secondary batteries are used not only in small products such as digital cameras, P-DVDs, MP3Ps, mobile phones, PDAs, portable game devices, power tools, and e-bikes, but also in large products that require high power such as electric vehicles and hybrid vehicles, as well as power storage devices for storing surplus generated power and new / renewable energy and backup power storage devices. Types of secondary batteries include nickel cadmium batteries, nickel metal hydride batteries, lithium ion batteries, and lithium ion polymer batteries.

[0003] A secondary battery 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 type, can type, etc. according to the material of the case that houses the electrode assembly. Among them, a pouch-type battery can be manufactured by performing press working on a flexible pouch film laminate to form a cup portion, then housing the electrode assembly in the accommodation space inside the cup portion, and sealing the seal portion.

[0004] In a pouch-type secondary battery, gas may be generated inside the pouch during high-temperature driving, overcharging, or short circuit occurrence. When the gas pressure inside the pouch increases, there is a problem that the pouch is bent and explodes or catches 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 and a battery pack containing the same, which solve the problem of moisture penetration or electrolyte leakage due to stretching of the film in the gas-permeable portion of a secondary battery equipped with a gas induction portion, by applying a reinforcing film to prevent deformation of the gas induction portion, while maintaining an appropriate gas discharge rate.

[0007] Furthermore, in the aforementioned secondary battery, a reinforcing film is applied to prevent deformation of the gas induction portion. By arranging the reinforcing film so as to be inserted into the sealing portion, deformation of the film is prevented while improving the sealing strength of the gas induction portion and the portion to which the reinforcing film is added, thereby providing a pouch-type secondary battery including a gas induction portion and a battery pack including the same. [Means for solving the problem]

[0008] [1] In one aspect of this specification, a pouch-type secondary battery is provided, comprising: an electrode assembly; an outer material including a housing for housing the electrode assembly and a terrace portion formed around the housing and having a sealed portion having a portion of its width sealed; electrode leads electrically connected to the electrode assembly and protruding to the outside of the outer material; a lead film disposed between the electrode leads and the outer material; a gas induction portion disposed between the electrode leads and the lead film and including a permeable portion provided outside the sealed portion and one or more gas channels extending from the permeable portion to the electrode assembly via the sealed portion; and a reinforcing film disposed on the lead film such that at least a portion of the permeable portion is covered, wherein the reinforcing film includes an insertion portion occupying a portion of the width of the sealed portion, the insertion portion being a region in which one end of the reinforcing film extends inward toward the outer material and is inserted between the outer material and the lead film of the sealed portion.

[0009] [2] In the above [1], the pouch-type secondary battery may be configured such that, due to an increase in the internal pressure of the outer casing material, the interface between the lead film and the gas induction film along the gas flow path is opened, thereby providing a gas discharge path.

[0010] [3] In the above [1] and / or [2], the reinforcing film may be placed on the lead film such that the entire transparent portion is covered.

[0011] [4] In at least one of the above [1] to [3], the reinforcing film may have a tensile strength of 6.0 MPa to 9.0 MPa at 60°C.

[0012] [5] In at least one of the above [1] to [4], the ratio of the length of the insertion portion of the reinforcing film to the width of the sealing portion may be 0.05 to 0.90.

[0013] [6] In at least one of the above [1] to [5], the reinforcing film may have a thickness of 60 μm to 150 μm.

[0014] [7] In at least one of the above [1] to [6], the reinforcing film may include an adhesive layer in contact with the lead film and an insulating layer on which a portion of the surface is exposed to the outside.

[0015] [8] In at least one of the above [1] to [7], the reinforcing film may include an adhesive layer in contact with the lead film and an insulating layer on which a portion of the surface is exposed to the outside, wherein the adhesive layer includes a modified polyolefin resin and the insulating layer includes an unmodified polyolefin resin.

[0016] [9] In at least one of the above [1] to [8], the reinforcing film may include an adhesive layer in contact with the lead film, an insulating layer with a portion of its surface exposed to the outside, and an intermediate layer disposed between the adhesive layer and the insulating layer.

[0017]

[10] In at least one of the above [1] to [9], the reinforcing film includes an adhesive layer in contact with the lead film, an intermediate layer disposed on the adhesive layer, and an insulating layer disposed on the intermediate layer with a portion of its surface exposed to the outside, wherein the adhesive layer may have a lower melting point (Tm) than the intermediate layer.

[0018]

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

[10] , the reinforcing film includes an adhesive layer in contact with the lead film, an intermediate layer disposed on the adhesive layer, and an insulating layer disposed on the intermediate layer with at least a portion of its surface exposed to the outside, wherein the adhesive layer includes a modified polyolefin resin, and the intermediate layer and the insulating layer each independently include an unmodified polyolefin resin.

[0019]

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

[11] , the gas induction portion may include an adhesive resin layer in contact with the electrode lead and a permeable resin layer in contact with the lead film.

[0020]

[13] In the above

[12] , the adhesive resin layer may have one end that protrudes outward from the exterior material and protrudes further than one end of the permeable resin layer that protrudes outward from the exterior material.

[0021]

[14] In the above

[12] and / or

[13] , the lead film may have one end that protrudes outward from the exterior material and that protrudes further than one end of the permeable resin layer that protrudes outward from the exterior material.

[0022]

[15] In another aspect of this specification, a battery pack is provided comprising a plurality of pouch-type secondary batteries and packaging for housing the pouch-type secondary batteries, the pouch-type secondary batteries comprising an electrode assembly, an outer material including a housing for housing the electrode assembly and a terrace formed around the housing and having a sealed portion having a portion of its width sealed, electrode leads electrically connected to the electrode assembly and protruding to the outside of the outer material, a lead film disposed between the electrode leads and the outer material, a gas induction portion disposed between the electrode leads and the lead film and including a permeable portion provided outside the sealed portion and one or more gas channels extending from the permeable portion to the electrode assembly via the sealed portion, and a reinforcing film disposed on the lead film so as to cover at least a portion of the permeable portion, the reinforcing film including an insertion portion in which a portion of the end extending inward toward the outer material is inserted between the outer material and the lead film of the sealed portion. [Effects of the Invention]

[0023] In one embodiment of this specification, a pouch-type secondary battery and battery pack have the advantage of preventing the whitening phenomenon that occurs when the lead film is subjected to continuous tension due to gas discharge, solving the problem of electrolyte leakage, and reducing the possibility of moisture penetration from a long-term perspective, by introducing a reinforcing film that covers the permeable portion of the gas induction section.

[0024] In other aspects of the present specification, the pouch-type secondary battery and the battery pack introduce a reinforcing film that covers the permeable portion of the gas guiding portion. By inserting a part of the reinforcing film into the sealing region and sealing them together, even if the process of opening the interface between the gas guiding portion and the lead film is repeated during gas discharge, the sealing strength is excellent, and deformation of the film such as a phenomenon where a part of the film is pushed or a specific interface peels off can be prevented. Therefore, an improvement in durability can be expected.

Brief Description of the Drawings

[0025] [Figure 1] It is an exploded view of a pouch-type secondary battery. [Figure 2] It is a cross-sectional view of a sealed pouch-type secondary battery. [Figure 3] It is an example of an enlarged cross-sectional view of the box A portion in FIG. 2, showing the state before the interface between the lead film and the gas guiding portion is opened. [Figure 4] It is an example of an enlarged cross-sectional view of the box A portion in FIG. 2, showing the state after the interface between the lead film and the gas guiding portion is opened. [Figure 5] It is another example of an enlarged cross-sectional view of the box A portion in FIG. 2, showing the state before the interface between the lead film and the gas guiding portion is opened. [Figure 6] It is yet another example of an enlarged cross-sectional view of the box A portion in FIG. 2, showing the state before the interface between the lead film and the gas guiding portion is opened. [Figure 7] It is an example of a top perspective view in the B direction of the box A portion in FIG. 2. [Figure 8] It is a cross-sectional view of a two-layer structure reinforcing film. [Figure 9] It is a cross-sectional view of a three-layer structure reinforcing film.

Modes for Carrying Out the Invention

[0026] 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 with ordinary skill in the art 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] In this specification, the term "A and / or B" means A, B, or A and B.

[0031] In this specification, "%" means weight percent unless otherwise explicitly indicated.

[0032] The pouch-type rechargeable batteries and battery packs described herein include at least one of the technical configurations described below, and may include any combination of technically feasible configurations from the following technical configurations.

[0033] In one embodiment, a pouch-type secondary battery includes an electrode assembly, an outer material including a housing for housing the electrode assembly and a terrace formed around the housing, an electrode lead connected to the electrode assembly and protruding to the outside of the outer material via the terrace, a lead film disposed between the electrode lead and the outer material, a gas induction portion disposed between the electrode lead and the lead film, and a reinforcing film disposed on the lead film.

[0034] Furthermore, in the pouch-type secondary battery, the terrace portion is provided with a sealing portion in which a part of its width is sealed along the perimeter of the housing portion, the gas induction portion includes a permeable portion provided on the outside of the sealing portion and one or more gas passages provided such that the permeable portion and the inside of the outer casing material are connected to each other via the sealing portion, the reinforcing film covers the entire surface of the permeable portion of the gas induction portion and includes an insertion portion in which a part of the end extending in the direction toward the inside of the case is inserted between the case and the lead film on the sealing portion, and the reinforcing film has a multilayer structure and includes an adhesive layer in contact with the lead film and an insulating layer in which a part of the surface is exposed to the outside.

[0035] First, we will provide an overview of the components of the pouch-type secondary battery by referring to the diagram.

[0036] Figure 1 is an exploded assembly diagram of the pouch-type secondary battery 100, 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 includes an outer casing 110, an electrode assembly 160, electrode leads 180, lead film 190, a gas induction section 200, and a reinforcing film 300.

[0037] (1) Exterior materials In one embodiment, the exterior material 110 can house the electrode assembly 160 inside. The exterior material 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 can be laminated sequentially.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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 since the overall thickness of the pouch does not increase, it provides excellent volume-specific energy density for the secondary battery.

[0042] 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 outer packaging material.

[0043] 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).

[0044] 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.

[0045] The sealant layer is intended to completely seal the interior of the exterior material by being heat-bonded to each other at the sealing portion when the exterior material, which houses the electrode assembly inside, is sealed. For this purpose, the sealant layer may be formed from a material having excellent heat bonding strength.

[0046] 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 exterior material, 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 exterior material and block the movement of substances between the inside and outside, it may be formed from a material that has 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.

[0047] 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.

[0048] 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.

[0049] The pouch film laminate may be drawn and stretched by punching or the like for the manufacture of the outer packaging material 110. As a result, the outer packaging material 110 may include a cup portion 122 and a housing portion 124. The housing portion 124 is a portion for housing the electrode assembly and can mean a housing space that is formed in a pocket shape inside the cup portion 122 when the cup portion 122 is formed.

[0050] In one embodiment, the exterior material 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 the 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 outside of 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.

[0051] In another embodiment, when forming cup portions on a pouch film laminate, drawing-molding may be performed so that two symmetrical cup portions 122 and 132 are adjacent to each other on one pouch film laminate. In that case, cup portions 122 and 132 can be formed on 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 one electrode assembly 160 is housed by two cup portions 122 and 132, 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 outer casing material 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.

[0052] The outer casing material 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).

[0053] 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.

[0054] 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 exterior material 110 can ensure sufficient sealing strength through heat bonding.

[0055] (2) Electrode assembly In one embodiment, the electrode assembly 160 may be inserted into the outer casing material 110, injected with electrolyte, and then sealed by the outer casing material 110.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] The electrode assembly 160 may include an electrode tab 170.

[0060] 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.

[0061] (3) Electrode lead In one embodiment, 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.

[0062] The electrode lead 180 may be connected to the electrode assembly 160 and protrude to the outside of the outer casing material 110 via the seal 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 outer casing material 110 via the terrace portion 150.

[0063] 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.

[0064] One surface of the electrode lead 180 that is in direct contact with the lead film 190 and / or the gas induction portion 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 portion 200 can be ensured.

[0065] (4) Lead film In one embodiment, 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 easily. Generally, insulating tape that is easy to attach to the electrode leads 180 and / or the gas induction section 200 and is relatively thin is often used as the lead film 190, but it is not limited to this, and any material that can insulate the electrode leads 180 may be used.

[0066] The lead film 190 may be arranged to surround the outer circumferential surfaces of the electrode lead 180 and the gas induction portion 200. Specifically, the electrode lead 180 and the gas induction portion 200 may be in contact with each other on one side, and at least a portion of the electrode lead 180 and the gas induction portion 200 may be surrounded by the lead film 190. The lead film 190 is positioned exclusively within the seal portion 150 where the first case 120 and the second case 130 of the outer casing material 110 are heat-fused together, allowing the electrode lead 180 and the gas induction portion 200 to be bonded to the battery case 110.

[0067] The lead film 190 may be placed between the electrode lead 180 and / or the gas induction section 200 and the outer casing material 110. For example, as shown in Figure 2, the lower case 110, lead film 190, electrode lead 180, gas induction section 200, lead film 190, and upper case 110 may be arranged in a sequentially stacked state in the terrace section 150 region.

[0068] 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.

[0069] The metal adhesive layer may be in direct contact with the electrode lead 180 and may 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 a modified polyolefin resin, for example, an acid-modified polyolefin. For example, the metal adhesive layer may contain, but is not limited to, at least one of acid-modified polypropylene (PPa), acid-modified polyethylene (PEa), and 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-pinholes and leaks at the edge when the electrode lead and lead film are fused together.

[0070] The aforementioned acid-modified polyolefin means a polyolefin resin that has been graft-modified with an 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.

[0071] The core layer may be a layer located in the center of the lead film 190. The core layer may contain an unmodified polyolefin resin, and may contain additives such as polypropylene resin, polyolefin elastomer (POE), and / or colorants, but is not limited to these. Among these, the core layer may contain, for example, a polypropylene homopolymer. When the core layer contains a polypropylene homopolymer, the melting point of the core layer can be controlled to an appropriate numerical range, and thermal deformation 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.

[0072] 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 an unmodified polyolefin resin, for example, a polypropylene resin or a polyolefin elastomer (POE), but is not limited to these. Among these, the pouch adhesive layer may contain a polypropylene copolymer such as a polypropylene random copolymer or a polypropylene block copolymer. When the pouch adhesive layer contains such a copolymer, the melting point of the pouch adhesive layer can be controlled to an appropriate 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 meets the above numerical range, it has the effect of ensuring a sufficient residual polymer (e.g., polypropylene) to guarantee strength when sealing the electrode lead and the pouch film laminate.

[0073] (5) Gas induction section In one embodiment, the gas induction section 200 is provided for discharging gas from the inside of the exterior material 110 to the outside, and may include a permeable section 230 provided on the outside of the exterior material 110, and one or more gas flow paths 240 extending from the permeable section 230 toward the electrode assembly 160 via the sealing section.

[0074] As shown in Figure 2, the gas induction portion 200 of the present invention may be arranged 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 portion 200 is arranged, while the electrode lead 180 and the lead film 190 may come into direct contact in the region where the gas induction portion 200 is not arranged.

[0075] The gas induction section 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 interface between the gas induction section 200 and the lead film 190 is opened, and Figure 4 is a cross-sectional view of the pouch-type secondary battery after the interface between the gas induction section 200 and the lead film 190 is opened.

[0076] As shown in Figures 3 and 4, under normal conditions, the interface between the gas induction section 200 and the lead film 190 may not be open. However, when the internal pressure of the outer casing material 110 increases, the interface between the gas induction section 200 and the lead film 190 opens along the gas flow path 240, forming a gas discharge path 250. The gas inside the outer casing material 110 moves to the permeable section 230 along the gas discharge path 250 on the gas flow path 240. At that time, a gas pocket is formed on the permeable section 230, and the gas is discharged to the outside of the outer casing material 110 by passing through the lead film 190. As a result, the internal pressure of the outer casing material 110 can be reduced, preventing the secondary battery from exploding or igniting.

[0077] As shown in Figures 3 and 4, the gas induction portion 200 includes an adhesive resin layer 210 that contacts the electrode lead 180 and a permeable resin layer 220 disposed on the adhesive resin layer 210. The adhesive resin layer 210 may also be for contacting the electrode lead 180 and for bonding the gas induction portion 200 to the electrode lead 180.

[0078] In one embodiment, as shown in Figure 3, the adhesive resin layer 210 of the gas induction portion 200 may be formed to be longer than the permeable resin layer 220 at the end in the outward direction (E) of the exterior material. Thus, at the outward end (E) of the gas induction portion 200, a structure is formed in which the adhesive resin layer 210 is in direct contact with the lead film 190.

[0079] Independently thereafter, the end of the lead film 190 protruding outward (E) from the exterior material may be positioned to protrude further outward (E) than the end of the adhesive resin layer 210 in the same direction, and to be in direct contact with the electrode lead 180.

[0080] In addition, independently of that, the end of the lead film 190 protruding outward (E) from the exterior material may be positioned to protrude even further outward (E) than the end of the permeable resin layer 220 in the same direction.

[0081] When the adhesive resin layer 210 is formed to protrude further outward (E) from the exterior material than the permeable resin layer 220, or when the lead film 190 is formed to protrude further outward from one end of the permeable resin layer 220 and / or adhesive resin layer 210, the adhesive strength between the electrode lead 180 and the gas induction portion 200 and between the electrode lead 180 and the lead film 190 is excellent, thereby preventing a decrease in durability due to an increase in internal pressure, making it easy to secure the area of ​​the permeable portion 230 on the permeable resin layer 220, and enabling stable gas discharge.

[0082] In another embodiment, as shown in Figure 5, the lead film 190 may be positioned such that one end protruding outward (E) from the case protrudes further than the end of the gas induction section 200 in the outward (E) direction from the case and is in direct contact with the electrode lead 180. Independently, the outward (E) ends of the two layers of the gas induction section 200 may be formed to coincide.

[0083] In yet another embodiment, as shown in Figure 6, the adhesive resin layer 210 may be formed such that one end protruding outward (E) from the case protrudes further than the end of the permeable resin layer 220 in the outward (E) direction from the case, and the end of the adhesive resin layer 210 in the outward (E) direction coincides with the end of the lead film 190 in the outward (E) direction. In this case, the lead film 190 may have a structure in which it does not directly contact the electrode lead 180 but contacts the adhesive resin layer 210.

[0084] When the arrangement of the lead film 190, electrode lead 180, and gas induction portion 200 is formed as shown in Figures 3, 5, or 6, it is advantageous in terms of ensuring durability and securing the area of ​​the permeable portion 230 compared to when the lead film 190 is not arranged so that one end protrudes further outside the outer covering material 110 from the gas induction portion 200, but is instead arranged on the permeable resin layer 220 of the gas induction portion 200. The arrangement as shown in Figure 3 is most preferable, but in some cases the structure shown in Figures 5 or 6 can also be applied, and any structure can be selectively applied.

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

[0086] The aforementioned acid-modified polyolefin means 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 apply maleic anhydride so that the adhesive strength between the gas induction part 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).

[0087] The 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 the polyolefin resin that forms 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.

[0088] 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).

[0089] 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 section 200 and the electrode lead 180 to be easily fused together.

[0090] The permeable resin layer 220 may be a layer in contact with the lead film 190. The permeable resin layer 220 may contain one or more of polytetrafluoroethylene (PTFE) and polyimide (PI). The permeable resin layer 220 is preferable because, since it does not have high adhesion to the lead film 190, even if that portion is sealed, the interface with the lead film 190 opens when the internal pressure of the case 110 increases, thereby forming a gas discharge path 250.

[0091] 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 opens, forming a gas discharge path 250.

[0092] On the other hand, the ratio (D1 / D2) of the thickness of the adhesive resin layer (D1) to the thickness (D2) of the permeable resin layer 220 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 section 200 and the electrode lead 180 can be improved.

[0093] The permeable resin layer 220 and the adhesive resin layer 210 may be laminated by heat-pressing, or laminated after forming an adhesive layer between them, or they may be in the form of a tape in which an adhesive is applied to one side of the permeable resin layer 220 or the adhesive resin layer 210 and a release film is attached, and the layers are laminated after removing the release film. There are no particular restrictions on the method of laminating the permeable resin layer 220 and the adhesive resin layer 210, and any method other than those described above can be applied as long as the two layers can be properly bonded to each other.

[0094] (6) Reinforcement film In one embodiment, the reinforcing film 300 is arranged on the lead film 190 such that at least a portion of the permeable portion 230 of the gas induction portion 200 is covered, and is characterized in that it has the function of preventing whitening and reflection of the electrolyte.

[0095] The pouch-type secondary battery 100 has a series of mechanisms through which gas is discharged. When the internal pressure rises, the interface between the gas induction section 200 and the lead film 190 is opened, causing the laminate, including the lead film 190 and the outer casing material 110 above it, to be lifted upward only in the area where the gas induction section 200 is located, thereby forming a gas discharge path 250. Through this gas discharge path 250, the internal gas is discharged to the outside by passing through the lead film 190 in the permeable section 230.

[0096] If such a gas discharge mechanism is repeated, the lead film 190 located on the gas permeable portion, i.e., the permeable portion 230 region of the gas induction portion 200, will continue to be subjected to tension, and the tension on the lead film 190 will increase as the internal pressure rises, which can cause a whitening phenomenon in that portion. The whitening phenomenon can occur in the portion where the intermolecular bonding force has weakened, as the molecular structure inside the lead film is deformed by the continuous stretching of the lead film 190, the internal stress increases due to the deformation, and the intermolecular bonding force weakens as a result.

[0097] On the other hand, when the gas is released and the internal pressure decreases again, that is, when the series of charge-discharge reactions are completed and the device is placed in storage, and all the internal gas is released, the lifted lead film 190 returns to its original state and the gas discharge path 250 is closed again. When the gas discharge path 250 is closed, the possibility of electrolyte leakage to the outside is minimized. However, as mentioned above, areas where the intermolecular bonding force is weakened may occur inside the lead film 190, and the electrolyte may penetrate through these areas. This can lead to problems such as reflection of the electrolyte onto the permeable portion 230 of the gas induction portion 200 on the lead film 190, or in severe cases, leakage. Once the reflection of the electrolyte or leakage occurs, the possibility of moisture penetration from the outside also increases. Furthermore, if the above phenomena are repeated, the electrode lead 180 may corrode, and if the internal pressure increases, venting may occur, mainly around the areas where the bonding force of the lead film 190 is weakened.

[0098] Therefore, in one embodiment, the present inventors attempt to solve the above-mentioned problems by introducing a reinforcing film 300 onto the permeable portion 230 of the gas induction portion 200, which is a region on the lead film 190 through which gas permeates, in the pouch-type secondary battery 100. This suppresses the deterioration of the gas induction portion 200 and the lead film 190 due to continuous gas discharge, thereby ensuring durability.

[0099] In one embodiment, the reinforcing film 300 is characterized by including an insertion portion 301 that occupies a part of the width of the sealing portion 151. The insertion portion 301 can mean a region in which one end of the reinforcing film 300 extends in the inward direction (I) of the outer material and is inserted between the outer material and the lead film of the sealing portion 151. In this case, the sealing strength can be improved, thereby improving durability and preventing unintended venting by maintaining the sealing strength even when the interface between the lead film 190 and the gas induction portion 200 is repeatedly opened.

[0100] The insertion portion 301 of the reinforcing film 300 has a seal width (W) of the seal portion 151. S The ratio of the length to the seal portion may be 0.05 to 0.90. When the insertion portion 301 is formed such that the ratio of the length satisfies this range, it is possible to expect the advantage that seal strength can be secured at a level that does not reduce the processability of the sealing process. That is, if the reinforcing film 300 is deeply inserted within the seal width and the insertion portion 301 covers the entire seal portion 151, delamination may occur at the interface between the multilayer reinforcing films 300. Therefore, by ensuring that the end of the reinforcing film 300 in the inward direction (I) of the outer material covers only a part of the seal width, it is possible to cover it with the seal portion 151 and prevent the above-mentioned problem of delamination at the interface. To further achieve such effects, it is preferable that the ratio of the length is 0.07 or more, 0.09 or more, 0.10 or more, or 0.11 or more, and also 0.85 or less, 0.83 or less, 0.80 or less, 0.79 or less, or 0.78 or less.

[0101] Referring to Figures 3 and 4, a gas induction portion 200 is placed on the electrode lead 180, a lead film 190 is placed on the gas induction portion 200, and the reinforcing film 300 is placed on the lead film 190. The reinforcing film 300 may cover at least a part of the permeable portion 230 of the gas induction portion 200, and it is preferable to cover the entire surface of the permeable portion 230. When the reinforcing film 300 covers the entire surface of the permeable portion 230, it is not possible to rule out the possibility that the gas discharge rate will be relatively slower compared to when only a part is covered, but considering that it has excellent effects in preventing whitening and increasing durability, and that this can offset the decrease in gas discharge performance, it can be appropriately modified and applied depending on the application to which the secondary battery is applied.

[0102] The reinforcing film 300 may have an area based on its outer circumference that is 100% to 500% of the area of ​​the permeable portion 230 of the gas induction portion 200. That is, the reinforcing film 300 may be arranged to cover at least the entire area of ​​the permeable portion 230, and the area of ​​the permeable portion 230 (S A The reinforcing film 300 may be positioned to cover up to 500% of the transparent portion 230. While there are no particular problems if the area of ​​the reinforcing film 300 that covers the transparent portion 230 is designed to cover the entire area, this may be disadvantageous in terms of the sealing process and the thickness of the terrace portion after sealing, so it is preferable to design it to satisfy the aforementioned range. Furthermore, in order to effectively suppress the reflection phenomenon of the electrolyte and prevent the whitening phenomenon due to stretching, it is preferable to design the area of ​​the reinforcing film 300 to be 110% or more, 130% or more, or 150% or more of the area of ​​the transparent portion 230.

[0103] When designing the area of ​​the reinforcing film 300 to cover the permeable portion 230, the portion of the reinforcing film that exceeds the area of ​​the permeable portion 230 may also cover a part of the gas flow path 240.

[0104] In other words, the tension exerted on the lead film 190 at the point where the permeable portion 230 of the gas induction section 200 and the gas flow path 240 are in contact is relatively large. Therefore, in order to effectively prevent the reflection of the electrolyte and the whitening phenomenon due to stretching, when designing the reinforcing film 300 to exceed the area of ​​the permeable portion 230 of the gas induction section 200, it is preferable to design the reinforcing film 300 to be wide in the width direction of the electrode lead 180 and long in the length direction of the electrode lead 180, and to arrange it so as to cover not only the permeable portion 230 but also the gas flow path 240.

[0105] In one embodiment, the reinforcing film 300 can be one having a tensile strength of 6.0 MPa to 9.0 MPa at 60°C. Here, the tensile strength is the maximum force applied when the reinforcing film is cut to a width of 15 mm and a length of 90 mm, then both ends are inserted into a grip 20 mm apart using a UTM, and then stretched at 60°C at a rate of 1 mm / min by 20 mm. The tensile strength of the reinforcing film varies depending on the layer structure, the material of each layer, the thickness of each layer, etc., and it is easy for anyone with common technical knowledge in the industry to manufacture or obtain a reinforcing film 300 having a specific tensile strength.

[0106] The tensile strength of the reinforcing film 300 is preferably such that it can prevent deformation of the lead film 190 under tension and suppress the whitening phenomenon, and that the opening of the interface between the lead film 190 and the gas guide section 200 is not obstructed during gas discharge, thereby preventing the operating pressure from increasing. When the above range is satisfied, it is advantageous for achieving such effects, and is preferably 6.5 MPa or higher, 6.8 MPa or higher, or 7.0 MPa or higher, and also preferably 8.7 MPa or lower, or 8.5 MPa or lower.

[0107] In one embodiment, the reinforcing film 300 may have a multilayer structure, and referring to Figure 8, it has a two-layer structure, characterized by including an adhesive layer 320 that is in contact with the lead film and an insulating layer 310 whose surface is partially exposed to the outside.

[0108] The adhesive layer 320 of the reinforcing film 300 is a layer in contact with the lead film and can be made of a polyolefin resin, preferably a modified polyolefin resin. The modified polyolefin resin may be an acid-modified polyolefin or a plasma-treated polyolefin, and may include at least one of the following: acid-modified polypropylene (PPa), acid-modified polyethylene (PEa), and plasma-treated polypropylene.

[0109] The aforementioned 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 carboxyl groups (graft modification). The unsaturated carboxylic acid 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, tetrahydrophthalic acid, aconitic acid, maleic anhydride, itaconic anhydride, glutaconic anhydride, citraconic anhydride, aconitic acid anhydride, norbornenedicarboxylic acid anhydride, and tetrahydrophthalic anhydride. Among these, it is preferable to apply maleic anhydride so that the adhesive strength between the reinforcing film 300 and the lead film 190 can be improved.

[0110] The adhesive layer 320 of the reinforcing film 300 may contain a modified polyolefin resin, or it may further contain an unmodified polyolefin resin. The unmodified polyolefin resin can be the same type of material as the material contained in the insulating layer 310 described later, and may further contain polypropylene copolymers such as polypropylene random copolymer or polypropylene block copolymer. The unmodified polyolefin resin may also be an unstretched polyolefin, which is manufactured by casting without being stretched in a specific direction during the manufacturing or processing process, and is more flexible than stretched polyolefin resins, does not have the problem of tearing in a specific direction, and is relatively easy to process. When the unmodified polyolefin resin is contained in the adhesive layer 320, it is similar in material to the upper layer of the lead film 190 that is in contact with the reinforcing film 300, which is advantageous in achieving stronger sealing strength during sealing, and because the materials are similar, it is possible to expect the advantage of minimizing resistance at the interface when gas permeates and preventing a decrease in gas emission performance.

[0111] The adhesive layer 320 of the reinforcing film 300 may have a thickness of 30 μm to 65 μm, preferably 40 μm to 60 μm, and more specifically 45 μm to 55 μm. When the above thickness is met, the reinforcing film 300 can be stably attached to the lead film 190, minimizing the loss of gas discharge performance and the decrease in operating pressure.

[0112] The reinforcing film 300 may further include an insulating layer 310 on the adhesive layer 320. The insulating layer 310 may have its surface exposed to the outside, and in some cases, when forming an insertion portion 301, a part of it may be exposed, with the remainder being the insertion portion 301 and a layer in contact with the exterior material 110. A polyolefin resin can also be applied to this, and it is preferable to include an unmodified polyolefin resin. When an unmodified polyolefin resin is applied, it will be in contact with the exterior material 110 in part, but generally, a modified polyolefin resin is applied to the sealant layer, which is the innermost layer of the exterior material 110. This prevents excessive fusion during sealing, thus allowing the seal thickness to be maintained at or above a predetermined thickness, and is advantageous in ensuring processability, thus favorably acting in ensuring a high level of seal strength. Here, the unmodified polyolefin resin can be any resin described above that may be further included in the adhesive layer 320 in addition to the modified polyolefin resin.

[0113] Furthermore, the insulating layer 310 may further contain a coloring agent. The coloring agent may contain one or more selected from the group consisting of titanium dioxide, zinc oxide, iron oxide, and carbon black. The coloring agent may be present in an amount of about 0.1% to 1.0% by weight of the total weight of the insulating layer 310, and is preferably present in an amount of 0.2% or more by weight, 0.3% or more by weight, or 0.7% or less by weight, or 0.5% or less by weight. When the insulating layer 310 further contains such a coloring agent, it is possible to distinguish the boundaries between layers even after the reinforcing film 300 has been fused onto the lead film 190, which has the advantage of making dimensional control easy and allowing the area incorporated inside the exterior material to be visually confirmed.

[0114] The insulating layer 310 of the reinforcing film 300 may have a thickness of 10 μm to 45 μm, preferably 13 μm to 40 μm, and more specifically 10 μm to 30 μm. When the above thickness is met, the reinforcing film 300 performs the insulating function on top of the lead film 190, and the function of the insertion portion 301 described above can operate smoothly, minimizing the loss of gas discharge performance and the decrease in operating pressure.

[0115] In one embodiment, the reinforcing film 300 may have a multilayer structure, and referring to Figure 9, it may have a three-layer structure, including an adhesive layer 320 in contact with the lead film, an intermediate layer 330 disposed on the adhesive layer, and an insulating layer 310 disposed on the intermediate layer with a portion of its surface exposed to the outside.

[0116] If the reinforcing film 300 has a three-layer structure, the adhesive layer 320 and the insulating layer 310 can be applied in the same way as in the case of a two-layer structure, and an intermediate layer 330 may be further included and arranged between the adhesive layer 320 and the insulating layer 310.

[0117] The intermediate layer 330 may have a melting point (Tm) even higher than the melting point (Tm) of the insulating layer 310 and / or adhesive layer 320. If the melting point of the intermediate layer 330 is higher than that of the other layers, there is an advantage in that the layer structure can be maintained during sealing and the sealing thickness can be ensured.

[0118] The intermediate layer 330 may contain an unmodified polyolefin resin, and may also contain additives such as polypropylene resin, polyolefin elastomer (POE), and / or colorants. The intermediate layer may also contain, for example, a polypropylene homopolymer. When a polypropylene homopolymer is included in the intermediate layer, it is easy to control its melting point to be higher than that of the other layers, which minimizes thermal deformation and is advantageous in terms of ensuring seal thickness and insulation. The colorant may also be included in the intermediate layer 330, and the expected effect of including it may be similar to that of the colorant included in the insulating layer 310.

[0119] The thickness of the intermediate layer 330 may be 15 μm to 50 μm, specifically 17 μm to 40 μm, or more specifically 20 μm to 40 μm. When the thickness of the intermediate layer satisfies the above numerical range, deformation due to heat applied during fusion and sealing is prevented, thus providing a robust design effect in terms of ensuring insulation.

[0120] The reinforcing film 300 may have a multilayer structure, and each film may have a structure in which two or three layers are laminated together. The overall thickness is preferably controlled to 60 μm to 150 μm. It is preferably 65 μm or more, 70 μm or more, 75 μm or more, 80 μm or more, 85 μm or more, 90 μm or more, 95 μm or more, and also preferably 140 μm or less, 130 μm or less, or 120 μm or less. Such thicknesses are preferable for obtaining the effects of improved durability, such as preventing the whitening phenomenon and improving seal strength, which are to be obtained by the reinforcing film, while minimizing the decrease in gas emission performance.

[0121] (7) Electrolyte The pouch-type secondary battery 100 according to the present invention may further include an electrolyte (not shown) injected into the interior of the outer casing material 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.

[0122] Battery pack In one embodiment, the battery pack may include pouch-type rechargeable batteries, which may consist of multiple pouch-type rechargeable batteries. The battery pack may also include packaging that houses multiple pouch-type rechargeable batteries. The packaging may be configured to protect the pouch-type rechargeable batteries from external shocks and contamination. A description of the pouch-type rechargeable batteries has been given above and will be omitted here.

[0123] The aforementioned packaging can be a box-shaped structure. The packaging may be made of a metal or plastic having a predetermined rigidity. The packaging may have a structure in which multiple plates are joined together.

[0124] The shape and structure of the packaging can be modified as needed. For example, at least a portion of the packaging may have a bent shape. The packaging may also be further equipped with other components. For example, the packaging may be equipped with busbars electrically connected to multiple secondary batteries and / or venting components that connect the inside and outside of the packaging. [Examples]

[0125] 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.

[0126] Examples and Comparative Examples Example 1 (1) Manufacturing of exterior materials A pouch film laminate with a polyethylene terephthalate film / nylon film / aluminum alloy thin film / polypropylene film structure was manufactured by laminating a polyethylene terephthalate (PET) film (266 mm wide, 50 m long, 12 μm thick) and a nylon film (266 mm wide, 50 m long, 25 μm thick) onto one side of an aluminum alloy thin film (266 mm wide, 50 m long, 60 μm thick), and laminating a polypropylene film (266 mm wide, 50 m long, 80 μm thick) onto the other side.

[0127] 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.

[0128] An outer packaging material including a housing section and a sealing section was manufactured by molding the aforementioned pouch film laminate.

[0129] (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.

[0130] An electrolyte was prepared by dissolving LiPF6 in a solvent (EC:EMC:DMC = 3:3:4 by volume) to a concentration of 1.0 M. The electrode assembly was placed in the outer casing with the tips of the electrode leads extended to the outside, and the electrolyte was poured in.

[0131] A gas induction section was formed by attaching a 50 μm thick polytetrafluoroethylene tape (permeable resin layer) to a 43 μm thick acid-modified polypropylene film (adhesive resin layer) on the upper surface of the electrode lead.

[0132] 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 portion, respectively. The lead film comprises a 75 μm thick metal adhesive layer containing polypropylene random copolymer and acid-modified polypropylene, a 65 μm thick core layer containing homopolymer polypropylene, and a 60 μm thick pouch adhesive layer containing copolymer polypropylene.

[0133] Finally, a reinforcing film is placed on the upper surface of the lead film on which the gas induction portion is formed. The reinforcing film is inserted approximately 11% of the seal width in the inward direction of the case, and is positioned to cover the entire surface of the permeable portion in the outward direction.

[0134] The reinforcing film used had a structure in which a 50 μm thick film containing acid-modified polypropylene and polypropylene random copolymer (adhesive layer), a 30 μm thick film containing polypropylene monopolymer (intermediate layer), and a 20 μm thick film containing polypropylene random copolymer (insulating layer) were sequentially laminated on the upper surface of the lead film, and had a tensile strength of 7 MPa at 60°C. Here, the tensile strength was the maximum force applied when the reinforcing film was cut to a width of 15 mm and a length of 90 mm, then 20 mm each end was inserted into the grip using a UTM, and then stretched by 20 mm at a rate of 1 mm / min at 60°C.

[0135] Subsequently, a pouch-type secondary battery was manufactured by sealing the sealing portion of the exterior material for 2 seconds under the conditions of a sealing bar area of ​​200 mm x 10 mm, 220°C, and 0.20 MPa.

[0136] Example 2 A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that when positioning the reinforcing film, it was inserted approximately 33% of the seal width in the inward direction of the case, and positioned to cover the entire surface of the permeable portion in the outward direction.

[0137] Example 3 A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that when positioning the reinforcing film, it was inserted approximately 78% of the seal width in the inward direction of the case, and positioned to cover the entire surface of the permeable portion in the outward direction.

[0138] Example 4 A pouch-type secondary battery was manufactured in the same manner as in Example 3, except that when positioning the reinforcing film, it was inserted approximately 78% of the seal width in the inward direction of the case, and positioned to cover the entire surface of the permeable portion in the outward direction, and a reinforcing film with a tensile strength of 9 MPa at 60°C was used as the reinforcing film.

[0139] Comparative Example 1 A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a reinforcing film was not formed.

[0140] Comparative Example 2 A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that when positioning the reinforcing film, it was not inserted in the inner direction of the case so as not to overlap with the seal width, and the reinforcing film was positioned in the outer direction so as to cover the entire surface of the transparent area.

[0141] Comparative Example 3 A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that when positioning the reinforcing film, it was inserted deeply into the case in the inward direction to cover the entire width of the seal, and positioned to cover the entire surface of the permeable portion in the outward direction.

[0142] Experimental Example 1: Measurement of Gas Emission Rate The gas discharge rate was measured for the pouch-type secondary batteries manufactured in Examples 1-4 and Comparative Examples 1-3, respectively.

[0143] 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 2.5 atm. The amount of gas discharged was then measured for 24 hours, and the results are shown in Table 1 below.

[0144] Experimental Example 2: Measurement of the operating pressure of the gas induction section The internal pressure at which gas discharge begins was measured for the pouch-type secondary batteries manufactured in Examples 1-4 and Comparative Examples 1-3, respectively.

[0145] 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 0.5 atm increments while being left for 24 hours at each pressure level. The pressure at which the permeable portion of the gas induction section was completely deformed (the interface between the lead film in the permeable portion and the gas induction section was completely open) was measured, and the results are shown in Table 1 below.

[0146] Experiment Example 3: Presence or absence of film deformation and reflection of electrolyte. For the pouch-type secondary batteries manufactured in Examples 1-4 and Comparative Examples 1-3, the permeate solution (mega check, MAGNAFLUX) was added to the electrolyte to a concentration of 0.1% by weight. CO2 (dry ice) was then injected into the pouch-type secondary batteries to increase the internal pressure of the pouch to 2.0 atm. After that, the batteries were kept at 60°C for 5 days to check for deformation of the lead film at the edge of the gas induction section and for any reflection of the electrolyte.

[0147] Experimental Example 4: Measurement of Seal Strength For the pouch-type secondary batteries manufactured in Examples 1-4 and Comparative Examples 1-3, the seal portion was cut at 15 mm intervals, the electrode leads were then attached to the lower jig of the UTM, the outer casing material was attached to the upper jig, and then the seal strength was measured by pulling it in a 180° direction at a speed of 5 mm / min at room temperature. The low-speed seal strength was calculated by calculating the average value in the 8 mm interval from the point where it exceeded 4.5 kgf / 15 mm in the graph of the measured seal strength.

[0148] [Table 1]

[0149] According to Table 1 above, it can be confirmed that the secondary batteries of Examples 1 to 4 achieved excellent sealing strength while showing no film deformation. In the case of Comparative Example 1, although it showed superior gas emission performance because no reinforcing film was attached, film deformation was observed, the reflection of the electrolyte was observed, and the sealing strength was low, confirming that it could not be applied to actual products due to poor durability. In Comparative Example 2, in which no reinforcing film was inserted into the sealing width, it was confirmed that a durability problem occurred due to film deformation, and in Comparative Example 3, in which the reinforcing film was inserted into the entire sealing width, it was found that the sealing strength decreased sharply. Therefore, when attempting to prevent film deformation by attaching a reinforcing film to the lead film as in Examples 1 to 4 above, it was confirmed that the dimensions should be designed so that only a portion of the film is inserted into the sealing width, and the entire film is not inserted. [Explanation of symbols]

[0150] 100 pouch-type rechargeable batteries 110 Exterior materials 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 section 210 Adhesive resin layer 220 Transparent resin layer 230 Transparent part 240 Gas flow path 250 Gas Emissions Pathways 300 Reinforcement Film 301 Insertion section 310 Insulating layer 320 Adhesive layer 330 Middle Class

Claims

1. Electrode assembly and An exterior material including a housing section for housing the electrode assembly, and a terrace section formed around the housing section, with a sealed section having a portion of its width sealed; An electrode lead is electrically connected to the electrode assembly and protrudes from the exterior of the outer casing, A lead film is disposed between the electrode lead and the outer material, A gas induction section is provided between the electrode lead and the lead film, and includes a permeable portion located outside the sealing portion and one or more gas flow channels extending from the permeable portion toward the electrode assembly via the sealing portion. The reinforcing film is disposed on the lead film so as to cover at least a portion of the transparent portion, The reinforcing film is It includes an insertion portion that occupies a part of the width of the sealing portion, The insertion portion is a region where one end of the reinforcing film extends inward from the outer material and is inserted between the outer material and the lead film of the sealing portion, in a pouch-type secondary battery.

2. The aforementioned pouch-type rechargeable battery is The pouch-type secondary battery according to claim 1, wherein an increase in the internal pressure of the outer casing material causes the interface between the lead film and the gas induction portion to open along the gas flow path, thereby providing a gas discharge path.

3. The reinforcing film is The pouch-type secondary battery according to claim 1, wherein the lead film is arranged so as to cover the entire transparent portion.

4. The reinforcing film is A pouch-type secondary battery according to claim 1, wherein the tensile strength at 60°C is 6.0 MPa to 9.0 MPa.

5. The reinforcing film is The pouch-type secondary battery according to claim 1, wherein the ratio of the length of the insertion portion to the width of the sealing portion is 0.05 to 0.

90.

6. The reinforcing film is A pouch-type secondary battery according to claim 1, wherein the thickness is 60 μm to 150 μm.

7. The reinforcing film is The pouch-type secondary battery according to claim 1, comprising an adhesive layer in contact with the lead film and an insulating layer whose surface is partially exposed to the outside.

8. The reinforcing film is It includes an adhesive layer that is in contact with the lead film and an insulating layer whose surface is partially exposed to the outside, The pouch-type secondary battery according to claim 1, wherein the adhesive layer comprises a modified polyolefin resin, and the insulating layer comprises an unmodified polyolefin resin.

9. The reinforcing film is The pouch-type secondary battery according to claim 1, comprising an adhesive layer in contact with the lead film, an insulating layer with a portion of its surface exposed to the outside, and an intermediate layer disposed between the adhesive layer and the insulating layer.

10. The reinforcing film is It includes an adhesive layer in contact with the lead film, an intermediate layer disposed on the adhesive layer, and an insulating layer disposed on the intermediate layer with a portion of its surface exposed to the outside, The pouch-type secondary battery according to claim 1, wherein the adhesive layer has a lower melting point (Tm) than the intermediate layer.

11. The reinforcing film is The adhesive layer is in contact with the lead film, the intermediate layer is disposed on the adhesive layer, and the insulating layer is disposed on the intermediate layer with at least a portion of its surface exposed to the outside. The pouch-type secondary battery according to claim 1, wherein the adhesive layer comprises a modified polyolefin resin, and the intermediate layer and the insulating layer each independently comprise an unmodified polyolefin resin.

12. The aforementioned gas induction section is The pouch-type secondary battery according to claim 1, comprising an adhesive resin layer in contact with the electrode leads and a permeable resin layer in contact with the lead film.

13. The aforementioned adhesive resin layer is The pouch-type secondary battery according to claim 12, wherein one end of the exterior material that protrudes outward protrudes further than one end of the permeable resin layer that protrudes outward from the exterior material.

14. The lead film is The pouch-type secondary battery according to claim 12, wherein one end of the exterior material that protrudes outward protrudes further than one end of the permeable resin layer that protrudes outward from the exterior material.

15. The invention includes a plurality of pouch-type secondary batteries and packaging for housing the pouch-type secondary batteries. The aforementioned pouch-type rechargeable battery is Electrode assembly and An exterior material including a housing section for housing the electrode assembly, and a terrace section formed around the housing section, with a sealed section having a portion of its width sealed; An electrode lead is electrically connected to the electrode assembly and protrudes from the exterior of the outer casing, A lead film is disposed between the electrode lead and the outer material, A gas induction section is provided between the electrode lead and the lead film, and includes a permeable portion located outside the sealing portion and one or more gas flow channels extending from the permeable portion toward the electrode assembly via the sealing portion. The reinforcing film is disposed on the lead film so as to cover at least a portion of the transparent portion, The reinforcing film is A battery pack in which a portion of the end of the outer casing material that extends inward is inserted between the outer casing material of the sealing portion and the lead film.

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