Pouch-type secondary battery and battery pack including the same

Abstract

The pouch-type secondary battery according to the present invention comprises: an electrode assembly; an outer material including an accommodating unit for accommodating the electrode assembly, and a platform unit formed along a periphery of the accommodating unit and having a sealing unit in which a portion of a width is sealed; an electrode lead electrically connected to the electrode assembly and protruding to the outside of the outer material; a lead film disposed between the electrode lead and the external material; a gas sensing unit disposed between the electrode lead and the lead film, and including a transport unit disposed on an exterior of the exterior material, and at least one gas flow path extending from the transport unit toward the electrode assembly via the sealing unit; and a reinforcing film disposed on the lead film to cover at least a portion of the transfer unit.

Description

Technical Field

[0001] The present invention relates to a pouch-type secondary battery and a battery pack including the same, and more particularly, to a pouch-type secondary battery and a battery pack including a gas guide portion. Background Art

[0002] Secondary batteries have been used in a variety of fields, including not only small products such as digital cameras, P-DVDs, MP3 players, mobile phones, PDAs, portable game devices, power tools, and electric bicycles, but also large products that require high output, such as electric vehicles and hybrid vehicles, as well as power storage devices for storing surplus generated electricity or renewable energy and power storage devices for backup. 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 prepared by accommodating an electrode assembly in which a positive electrode, a negative electrode, and a separator disposed therebetween are alternately stacked in a battery case, injecting an electrolyte, and then sealing the battery case. Depending on the material of the case for accommodating the electrode assembly, secondary batteries are classified into pouch-type secondary batteries, can-type secondary batteries, and the like. After forming a cup-shaped portion by press-processing a flexible pouch film laminate, a pouch-type battery can be prepared by accommodating the electrode assembly in a accommodating space inside the cup-shaped portion and sealing the sealing portion.

[0004] During high-temperature operation, overcharging, or short circuit, gas may be generated in the pouch of a pouch-type secondary battery. In the case where the gas pressure in the pouch increases, there is a problem of explosion or ignition while venting the pouch.

[0005] Therefore, various types of gas exhaust components are being studied in order to solve the above-mentioned problems, and there is an increasing demand for gas exhaust components that take into account the problems of gas exhaust as well as moisture penetration and electrolyte leakage from the outside, gas exhaust components that operate at low pressure while enduring high internal pressure, and gas exhaust components with excellent durability. Summary of the Invention

[0006] Technical issues

[0007] One aspect of the present invention provides a pouch-type secondary battery and a battery pack including the pouch-type secondary battery. In the pouch-type secondary battery including a gas guide portion, by using a reinforcing film for preventing deformation of the gas guide portion, while maintaining a gas discharge rate at an appropriate level, the problem of moisture penetration or electrolyte solution leakage caused by stretching of the film of the gas permeable portion according to gas discharge is solved, thereby improving durability.

[0008] Technical Solution

[0009] [1] According to an embodiment of the present invention, a pouch-type secondary battery is provided, comprising: an electrode assembly; an outer packaging material, the outer packaging material comprising a receiving portion for receiving the electrode assembly and a platform portion, the platform portion being formed along a periphery of the receiving portion and having a sealing portion in which a portion of the width of the platform portion is sealed; an electrode lead electrically connected to the electrode assembly and protruding to the outside of the outer packaging material; a lead film disposed between the electrode lead and the outer packaging material; a gas guide portion disposed between the electrode lead and the lead film and comprising a permeation portion disposed on the outside of the outer packaging material and one or more gas channels extending from the permeation portion via the sealing portion toward the electrode assembly; and a reinforcement film disposed on the lead film to cover at least a portion of the permeation portion.

[0010] [2] The pouch-type secondary battery according to [1] above, wherein the interface between the lead film and the gas guide portion can be opened along the gas passage due to an increase in the internal pressure of the outer packaging material to provide a gas discharge path.

[0011] [3] A pouch-type secondary battery according to [1] and / or [2] above, wherein the reinforcement film includes an insertion portion occupying a portion of the width of the sealing portion, wherein the insertion portion may be an area in which one end portion of the reinforcement film is inserted between the outer packaging material of the sealing portion and the lead film by extending in the inner side direction of the outer packaging material.

[0012] [4] The pouch-type secondary battery according to at least one of [1] to [3] above, wherein the area of ​​the reinforcement film based on the outer circumference may be 100% to 500% of the area of ​​the permeation portion.

[0013] [5] The pouch-type secondary battery according to at least one of [1] to [4] above, wherein the reinforcement film may be provided on the lead film to cover a portion of the gas channel and the entire permeation portion of the gas guide portion.

[0014] [6] The pouch-type secondary battery according to at least one of [1] to [5] above, wherein the reinforcement film has a hollow portion formed therein, wherein an area of ​​the hollow portion may be smaller than an area of ​​the permeation portion.

[0015] [7] The pouch-type secondary battery according to at least one of [1] to [6] above, wherein the reinforcement film has a hollow portion formed therein, wherein an area of ​​the hollow portion may be 50% to 90% of an area of ​​the permeation portion.

[0016] [8] The pouch-type secondary battery according to at least one of [1] to [7] above, wherein the reinforcement film may include at least one selected from the group consisting of a polyester-based resin, a polyolefin-based resin, a polyamide-based resin, and a polycarbonate-based resin.

[0017] [9] A pouch-type secondary battery according to at least one of [1] to [8] above, wherein the reinforcement film includes: an adhesive layer that contacts the lead film; and a protective layer that is disposed on the adhesive layer, wherein the protective layer may include at least one selected from the group consisting of a polyester-based resin, a polyolefin-based resin, a polyamide-based resin, and a polycarbonate-based resin.

[0018]

[10] A pouch-type secondary battery according to at least one of [1] to [9] above, wherein the reinforcement film has a hollow portion formed therein and includes: an adhesive layer in contact with the lead film; a protective layer disposed on the adhesive layer; and an insulating layer disposed on the protective layer, wherein the protective layer may include at least one selected from the group consisting of a polyester-based resin, a polyolefin-based resin, a polyamide-based resin, and a polycarbonate-based resin.

[0019]

[11] The pouch-type secondary battery according to at least one of [1] to

[10] above, wherein the gas guide portion may have a structure in which an adhesive resin layer and a permeable resin layer are stacked from an upper surface of the electrode lead.

[0020]

[12] The pouch-type secondary battery according to

[11] above, wherein one end portion of the adhesive resin layer protruding in the outer direction of the outer packaging material may protrude more than one end portion of the permeable resin layer protruding in the outer direction of the outer packaging material.

[0021]

[13] The pouch-type secondary battery according to

[11] and / or

[12] above, wherein one end portion of the lead film protruding in the outer direction of the outer packaging material can protrude more than one end portion of the permeable resin layer protruding in the outer direction of the outer packaging material.

[0022]

[14] According to another embodiment of the present invention, a battery pack is provided, comprising: a plurality of pouch-type secondary batteries; and a package member that accommodates the secondary batteries, wherein the pouch-type secondary batteries comprise: an electrode assembly; an outer packaging material, the outer packaging material comprising a accommodating portion that accommodates the electrode assembly and a platform portion, the platform portion being formed along a periphery of the accommodating portion and having a sealing portion in which a portion of the width of the platform portion is sealed; an electrode lead that is electrically connected to the electrode assembly and protrudes to the outside of the outer packaging material; a lead film that is disposed between the electrode lead and the outer packaging material; a gas guide portion that is disposed between the electrode lead and the lead film and comprises a permeation portion disposed on the outside of the outer packaging material and one or more gas channels extending from the permeation portion via the sealing portion toward the electrode assembly; and a reinforcement film that is disposed on the lead film to cover at least a portion of the permeation portion.

[0023] Beneficial effects

[0024] The pouch-type secondary battery and battery pack according to the present invention have the advantage that, by introducing a reinforcing film covering the permeable portion of the gas guiding portion and introducing a reinforcing film on the upper surface of the lead film, they prevent the whitening phenomenon that occurs when the lead film is continuously stretched as the gas is discharged, can solve the problem of electrolyte solution leakage, and can simultaneously reduce the possibility of moisture penetration.

[0025] In addition, since the pouch-type secondary battery and battery pack according to the present invention introduce a reinforcement film covering the permeation portion of the gas guide portion, the reduction in gas discharge rate caused by covering the reinforcement film on the permeation portion is minimized, and by controlling the materials of the layers constituting the reinforcement film, the area of ​​the reinforcement film covering the permeation portion, whether a hollow portion is formed, and the laminated structure, a gas guide portion with excellent durability can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an exploded assembly diagram of a pouch-type secondary battery.

[0027] Figure 2 is a cross-sectional view of a sealed pouch-type secondary battery.

[0028] Figure 3 yes Figure 2 FIG. 1 is an example of an enlarged cross-sectional view of a frame A of FIG. 1 , which illustrates a state before the interface between the lead film and the gas guide portion is opened.

[0029] Figure 4 yes Figure 2 FIG. 1 is an example of an enlarged cross-sectional view of a frame A of FIG. 1 , which illustrates a state in which the interface between the lead film and the gas guide portion is opened.

[0030] Figure 5 yes Figure 2 Another example of an enlarged cross-sectional view of frame A of , which illustrates a state before the interface between the lead film and the gas lead film is opened.

[0031] Figure 6 yes Figure 2 1 is another example of an enlarged cross-sectional view of frame A of , which illustrates a state before the interface between the lead film and the gas lead film is opened.

[0032] Figure 7 is a top perspective view of a portion of an electrode lead in which a reinforcement membrane covers the entire surface of the permeate portion of the gas guiding portion.

[0033] Figure 8 This is a top perspective view of a portion of an electrode lead in which a reinforcement membrane having a hollow portion is formed covering a portion of the surface of the permeation portion of the gas guide portion.

[0034] Figure 9 This is a top perspective view of a portion of an electrode lead in which a reinforcement membrane having a hollow portion is formed covering a portion of the surface of the permeation portion of the gas guide portion.

[0035] Figure 10 is an enlarged cross-sectional view of a double-layer structured reinforced film.

[0036] Figure 11 is an enlarged cross-sectional view of a three-layer structured reinforced film. DETAILED DESCRIPTION

[0037] The advantages and features of the present invention and the implementation method of the present invention will be explained by the following embodiments described with reference to the accompanying drawings. However, the present invention can be embodied in different forms and should not be construed as limited to the embodiments described herein. Instead, these embodiments are provided so that this disclosure will be comprehensive and complete and will fully convey the scope of the present invention to those skilled in the art. Furthermore, the present invention is limited only by the scope of the claims. Like reference numerals refer to like elements throughout.

[0038] Unless otherwise defined, all terms (including technical and scientific terms) used herein may be intended to have meanings understood by those skilled in the art. In addition, terms defined in general dictionaries should not be interpreted abnormally or exaggeratedly unless specifically defined.

[0039] The terms used herein are for the purpose of describing specific example embodiments only and are not intended to limit the present invention. In the specification, unless otherwise mentioned, terms in the singular may include plural forms. It will be further understood that when used in this specification, the terms "include" and / or "comprising" specify the presence of the stated components, but do not exclude the presence or addition of one or more other components.

[0040] In this specification, when a part is said to include a certain component, unless specifically described otherwise, it means that other components may also be included, rather than excluding other components.

[0041] In this specification, the description of "A and / or B" means A, or B, or A and B.

[0042] In this specification, unless otherwise specifically stated, the expression "%" means weight (wt) %.

[0043] The pouch-type secondary battery and the battery pack described in this specification include at least one of the technical configurations described below, and may include any combination between technically possible configurations among the following technical configurations.

[0044] The pouch-type secondary battery according to the present invention is characterized in that the pouch-type secondary battery includes: an electrode assembly; an outer packaging material, the outer packaging material including a accommodating portion for accommodating the electrode assembly and a platform portion, the platform portion being formed along the periphery of the accommodating portion and having a sealing portion, in which a portion of the width of the platform portion is sealed; an electrode lead, the electrode lead being electrically connected to the electrode assembly and protruding to the outside of the outer packaging material; a lead film, the lead film being arranged between the electrode lead and the outer packaging material; a gas guide portion, the gas guide portion being arranged between the electrode lead and the lead film and including a permeable portion arranged on the outside of the outer packaging material and one or more gas channels extending from the permeable portion via the sealing portion toward the electrode assembly; and a reinforcement film, the reinforcement film being arranged on the lead film to cover at least a portion of the permeable portion.

[0045] First, components of the pouch-type secondary battery of the present invention will be described in more detail with reference to the accompanying drawings.

[0046] Figure 1 is an exploded assembly diagram of a pouch-type secondary battery 100 according to the present invention, and Figure 2 is a cross-sectional view of a sealed pouch-type secondary battery 100. Figure 2 In the figure, some components of the pouch-type secondary battery 100 are omitted for ease of understanding. Figure 1 and Figure 2As illustrated in FIG, a pouch-type secondary battery 100 of the present invention includes an outer package material 110 , an electrode assembly 160 , an electrode lead 180 , a lead film 190 , a gas guide portion 200 , and a reinforcement film 300 .

[0047] (1) Outer packaging materials

[0048] According to an embodiment of the present invention, the outer packaging material 110 may contain the electrode assembly 160 therein. The outer packaging material 110 may be prepared by forming a bag film laminate. In this case, the bag film laminate may include a base material layer, a gas barrier layer, and a sealant layer. In the bag film laminate, the base material layer, the gas barrier layer, and the sealant layer may be laminated sequentially.

[0049] The base material layer is formed as the outermost layer of the pouch film laminate to protect the secondary battery from friction and collision with the outside. The base material layer is formed of a polymer so that the base material layer can electrically insulate the electrode assembly from the outside.

[0050] The base material layer may be formed of at least one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylene benzobisoxazole), polyarylate, Teflon, and glass fiber. Preferably, the base material layer may be formed of polyethylene terephthalate (PET), nylon, or a combination thereof having wear resistance and heat resistance.

[0051] The base material layer may have a single layer structure formed of any one material. Alternatively, the base material layer may have a composite layer structure formed by laminating two or more materials, respectively.

[0052] The thickness of the base material layer may be 5 μm to 50 μm, particularly 7 μm to 40 μm, and more particularly 25 μm to 38 μm. In the case where the thickness of the base material layer satisfies the above range, the energy density of the secondary battery relative to the volume may be excellent because the external insulation is excellent and the bag as a whole is not thick.

[0053] The gas barrier layer is laminated between the base material layer and the sealant layer to ensure the mechanical strength of the pouch, block the inflow and outflow of gas or moisture from the outside of the secondary battery, and prevent leakage of the electrolyte from the inside of the outer packaging material.

[0054] The gas barrier layer can be formed of a metal, and specifically, can be formed of an aluminum alloy thin film. In the case where the gas barrier layer is formed using an aluminum alloy thin film, the gas barrier layer is lightweight while ensuring mechanical strength equal to or greater than a predetermined level, can compensate for the electrochemical characteristics of the electrode assembly and the electrolyte, and can ensure heat dissipation characteristics. The aluminum alloy thin film may include a metal element other than aluminum (Al), for example, at least one selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0055] The thickness of the gas barrier layer may be 40 to 100 μm, particularly 50 to 90 μm, and more particularly 55 to 85 μm. In the case where the thickness of the gas barrier layer satisfies the above range, gas barrier performance and formability when forming the cup-shaped portion are excellent.

[0056] The sealant layer is used to completely seal the interior of the outer packaging material by thermally bonding each other at the sealing portion when sealing the outer packaging material containing the electrode assembly inside. For this purpose, the sealant layer can be formed of a material having excellent thermal bonding strength.

[0057] The sealant layer can be formed of a material having insulating properties, corrosion resistance, and sealing properties. Specifically, since the sealant layer is in direct contact with the electrode assembly and / or electrolyte inside the outer packaging material, the sealant layer can be formed of a material having insulating properties and corrosion resistance. In addition, since the sealant layer completely seals the interior of the outer packaging material to prevent the movement of the material between the inside / outside, the sealant layer can be formed of a material having high sealing properties (e.g., excellent thermal bonding strength). In order to ensure such insulating properties, corrosion resistance, and sealing properties, the sealant layer can be formed of a polymer material.

[0058] The sealant layer may be formed of at least one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, polyphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber, and may preferably be formed of a polyolefin-based resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may include cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene terpolymer.

[0059] The thickness of the sealant layer may be 30 to 130 μm, particularly 50 to 120 μm, and more particularly 70 to 100 μm. In the case where the thickness of the sealant layer satisfies the above range, there is an effect of ensuring the formability of the bag film laminate while ensuring the sealing strength of the sealed portion.

[0060] The bag film laminate can be draw-molded and stretched by a punch press or the like to prepare the outer packaging material 110. Therefore, the outer packaging material 110 may include a cup-shaped portion 122 and a receiving portion 124. The receiving portion 124 is a place for receiving the electrode assembly, wherein the receiving portion 124 may refer to a receiving space formed in a concave shape inside the cup-shaped portion 122 when the cup-shaped portion 122 is formed.

[0061] According to an embodiment of the present invention, the outer packaging material 110 may include a first shell 120 and a second shell 130. Figure 1 As shown in FIG. The first shell 120 includes a receiving portion 124 capable of receiving the electrode assembly 160, and the second shell 130 can cover the receiving portion 124 from the top so that the electrode assembly 160 is not separated to the outside of the outer packaging material 110. Figure 1 As illustrated in the figure, the first shell 120 and the second shell 130 can be prepared by connecting one side thereof to each other, but the present invention is not limited thereto, and the first shell 120 and the second shell 130 can be prepared in various ways, for example, the first shell 120 and the second shell 130 are separated from each other and prepared separately.

[0062] According to another embodiment of the present invention, in the case where the cup-shaped portion is formed on the bag film laminate, two symmetrical cup-shaped portions 122 and 132 can be draw-molded adjacent to each other on one bag film laminate. In this case, as shown in FIG. Figure 1 As shown in FIG, cup-shaped portions 122 and 132 can be formed in the first shell 120 and the second shell 130, respectively. After the electrode assembly 160 is accommodated in the accommodating portion 124 provided in the cup-shaped portion 122 of the first shell 120, the bridging portion 140 formed between the two cup-shaped portions 122 and 132 can be folded so that the two cup-shaped portions 122 and 132 face each other. In this case, the cup-shaped portion 132 of the second shell 130 can accommodate the electrode assembly 160 from above. Therefore, since the two cup-shaped portions 122 and 132 accommodate one electrode assembly 160, an electrode assembly 160 having a greater thickness can be accommodated than when there is only one cup-shaped portion 122. In addition, since one edge of the secondary battery 100 is formed by folding the outer packaging material 110, the number of edges to be sealed can be reduced when the sealing process is performed later. Therefore, the processing speed of the pouch-type secondary battery 100 can be increased, and the number of sealing processes can be reduced.

[0063] The outer packaging material 110 can be sealed in a state where it accommodates the electrode assembly 160, so that a portion of the electrode lead 180 described later, that is, the terminal portion is exposed. Specifically, when the electrode lead 180 is connected to the electrode tab 170 of the electrode assembly 160 and the lead film 190 is formed in the portion of the electrode lead 180, the electrode assembly 160 is accommodated in the accommodating portion 124 provided in the cup-shaped portion 122 of the first shell 120, and the second shell 130 can cover the accommodating portion 124 from the top. Subsequently, the electrolyte is injected into the accommodating portion 124, and a portion of the platform portion 150 formed on the edge along the periphery of the first shell 120 and the second shell 130 can be sealed to form a sealing portion (not shown).

[0064] The sealing portion may serve to seal the receiving portion 124. Specifically, the sealing portion may seal the receiving portion 124 while being formed on a platform portion 150 formed on an edge along a periphery of the receiving portion 124.

[0065] The temperature at which the sealing portion is sealed may be in the range of 180° C. to 250° C., particularly in the range of 200° C. to 250° C., and more particularly in the range of 210° C. to 240° C. In the case where the sealing temperature satisfies the above numerical range, the outer packaging material 110 can ensure sufficient sealing strength through thermal bonding.

[0066] (2) Electrode assembly

[0067] According to an embodiment of the present invention, the electrode assembly 160 may be inserted into the outer package material 110 and may be sealed by the outer package material 110 after an electrolyte is injected.

[0068] The electrode assembly 160 may be formed by sequentially stacking a positive electrode, a separator, and a negative electrode. Specifically, the electrode assembly 160 may include two types of electrodes, such as a positive electrode and a negative electrode, and a separator disposed between the electrodes to insulate the electrodes from each other.

[0069] The positive electrode and the negative electrode may be structures in which active material slurries are applied to electrode current collectors in the form of metal foil or metal mesh including aluminum and copper, respectively. The slurry can generally be formed by stirring particulate active material, auxiliary conductor, binder, and conductive agent in a state where a solvent is added. The solvent can be removed in a subsequent process.

[0070] A slurry mixed with an electrode active material, a binder, and / or a conductive agent is applied to a positive electrode current collector and a negative electrode current collector to prepare a positive electrode and a negative electrode, and the positive electrode and the negative electrode can be stacked on both sides of a separator to prepare an electrode assembly 160 in a predetermined shape. Types of the electrode assembly 160 may include a stacking type, a winding type, and a stacking and folding type, but are not limited thereto.

[0071] The electrode assembly 160 may include an electrode tab 170 .

[0072] The electrode tab 170 is connected to each of the positive electrode and the negative electrode of the electrode assembly 160 and protrudes from the electrode assembly 160 to the outside, so that the electrode tab 170 can be a path through which electrons can move between the inside and the outside of the electrode assembly 160. The electrode current collector included in the electrode assembly 160 may include a portion to which an electrode active material is applied and an end portion to which the electrode active material is not applied, that is, an uncoated portion. The electrode tab 170 may be formed by cutting the uncoated portion, or may be formed by connecting a separate conductive member to the uncoated portion by ultrasonic welding or the like. Figure 1 As illustrated in FIG, the electrode tabs 170 may protrude in different directions of the electrode assembly 160, respectively, but are not limited thereto, and may be formed to protrude in various directions, for example, the electrode tabs 170 protrude side by side in the same direction from one side of the electrode assembly 160.

[0073] (3) Electrode leads

[0074] According to an embodiment of the present invention, the electrode lead 180 may supply power 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.

[0075] The electrode lead 180 is connected to the electrode assembly 160 and may protrude to the outside of the outer packaging material 110 via the sealing portion 150. Specifically, one end of the electrode lead 180 is connected to the electrode assembly 160, especially the electrode tab 170, and the other end of the electrode lead 180 may protrude to the outside of the outer packaging material 110 via the platform portion 150.

[0076] The electrode lead 180 may include a positive lead 182 and a negative lead 184. One end of the positive lead 182 is connected to the positive electrode tab 172 and extends in the direction of the protrusion of the positive electrode tab 172. One end of the negative lead 184 is connected to the negative electrode tab 174 and extends in the direction of the protrusion of the negative electrode tab 174. The other ends of both the positive lead 182 and the negative lead 184 may protrude outside the outer packaging material 110. Therefore, the electricity generated inside the electrode assembly 160 can be supplied to the outside. In addition, since the positive electrode tab 172 and the negative electrode tab 174 are formed to protrude in various directions, the positive lead 182 and the negative lead 184 can also extend in various directions. The materials of the positive lead 182 and the negative lead 184 can be different from each other. That is, the positive electrode lead 182 may be formed of the same aluminum (Al) material as the positive electrode current collector, and the negative electrode lead 184 may be formed of the same copper (Cu) material or nickel (Ni)-coated copper material as the negative electrode current collector. Since a portion of the electrode lead 180 protruding to the outside of the outer packaging material 110 becomes a terminal portion, the electrode lead 180 may be electrically connected to an external terminal.

[0077] One surface of electrode lead 180 that directly contacts lead film 190 and / or gas guide portion 200 may be coated with at least one selected from the group consisting of chromium (Cr), nickel (Ni), aluminum oxide (Al2O3), zirconium (Zr)-based anhydrous oxide salts, and titanium (Ti)-based anhydrous oxide salts. In this case, corrosion resistance to the electrolyte solution and adhesion to lead film 190 and / or gas guide portion 200 can be ensured.

[0078] (4) Lead film

[0079] According to an embodiment of the present invention, the lead film 190 prevents the electricity generated from the electrode assembly 160 from flowing through the electrode lead 180 to the outer packaging material 110, and can maintain the seal of the outer packaging material 110. To this end, the lead film 190 can be formed of an insulator having non-conductivity that does not conduct electricity well. Generally, as the lead film 190, a relatively thin insulating tape that is easy to attach to the electrode lead 180 and / or the gas guide portion 200 is widely used, but the present invention is not limited thereto, and any member that can insulate the electrode lead 180 can be used.

[0080] Lead film 190 may be provided to surround the outer peripheral surfaces of electrode lead 180 and gas guide portion 200. Specifically, electrode lead 180 and gas guide portion 200 may contact each other on one side, and in this case, at least a portion of electrode lead 180 and gas guide portion 200 may be surrounded by lead film 190. Lead film 190 may be limitedly located at sealing portion 150 where first shell 120 and second shell 130 of outer packaging material 110 are heat-welded, and may adhere electrode lead 180 and gas guide portion 200 to outer packaging material 110.

[0081] The lead film 190 may be provided between the electrode lead 180 and / or the gas guide portion 200 and the outer packaging material 110. Figure 2 As illustrated in FIG, the lower case 110, the lead film 190, the electrode lead 180, the gas guide portion 200, the lead film 190, and the upper case 110 may be disposed in a region of the sealing portion 150 in a sequentially stacked state.

[0082] The lead film 190 may include one or more layers. Specifically, the lead film 190 may include a metal adhesive layer, a core layer, and a bag adhesive layer sequentially stacked.

[0083] The metal bonding layer is in direct contact with the electrode lead 180 and can be used to adhere the lead film 190 to the electrode lead 180. The metal bonding layer may include any material that is easily adhered to the electrode lead 180. Specifically, the metal bonding layer may include an acid-modified polyolefin. For example, the metal bonding layer may include at least one of acid-modified polypropylene (PPa), acid-modified polyethylene (PEa) and plasma-treated polypropylene (PP), but is not limited thereto. The thickness of the metal bonding layer may be in the range of 50 μm to 80 μm, particularly in the range of 50 μm to 75 μm, and more particularly in the range of 60 μm to 75 μm. In the case where the thickness of the metal bonding layer satisfies the above numerical range, there is an effect of preventing pinholes and leakage at the edge portions when the electrode lead and the lead film are welded together.

[0084] The core layer may be a layer located at the center of the lead film 190. The core layer may include additives, such as polypropylene, polyolefin elastomer (POE) and / or colorants, but is not limited thereto. The polymer contained in the core layer may be a homopolymer. In the case where a homopolymer is contained in the core layer, it is advantageous in ensuring insulation properties because the melting point of the core layer can be controlled within the above numerical range and deformation due to heat can be minimized. The thickness of the core layer may be in the range of 40 μm to 70 μm, particularly in the range of 50 μm to 70 μm, and more particularly in the range of 60 μm to 70 μm. In the case where the thickness of the core layer satisfies the above numerical range, by preventing deformation due to heat applied during welding and sealing, there is an effect of a robust design in ensuring insulation properties.

[0085] The bag adhesive layer may be a layer that is in direct contact with the outer packaging material 110, specifically the sealant layer of the bag film laminate. The bag adhesive layer may include polypropylene and polyolefin elastomer (POE), but is not limited thereto. The polymer contained in the bag adhesive layer may be a copolymer. In the case where the bag adhesive layer contains a copolymer, since the melting point of the bag adhesive layer can be controlled within the above numerical range and is similar to the melting point of the polymer in the sealant layer of the bag film laminate, it is advantageous in ensuring sealing workability. The thickness of the bag adhesive layer may be in the range of 40 μm to 100 μm, particularly in the range of 40 μm to 80 μm, and more particularly in the range of 40 μm to 60 μm. When the thickness of the bag adhesive layer satisfies the above numerical range, when sealing is performed between the electrode lead and the bag film laminate, it has the effect of ensuring a sufficient residual rate of polymer (e.g., polypropylene) to ensure strength.

[0086] (5) Gas guide part

[0087] According to an embodiment of the present invention, the gas guide portion 200 is used to discharge gas from the inside of the outer packaging material 110 to the outside, wherein the gas guide portion 200 may include a permeable portion 230 arranged on the outside of the outer packaging material 110 and one or more gas channels 240 extending from the permeable portion 230 via the sealing portion toward the electrode assembly 160.

[0088] like Figure 2 , the gas guide portion 200 of the present invention may be provided between the electrode lead 180 and the lead film 190. In this case, in the region between the electrode lead 180 and the lead film 190, the electrode lead 180 and the lead film 190 are not in direct contact in the region where the gas guide portion 200 is provided, and the electrode lead 180 and the lead film 190 may be in direct contact with each other in the region where the gas guide portion 200 is not provided.

[0089] In the following, reference will be made to Figure 3 and Figure 4 The gas guide portion 200 of the present invention will be described in more detail. Figure 3 is a cross-sectional view of a pouch-type secondary battery before the interface between the gas guide portion 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 guide portion 200 and the lead film 190 is opened.

[0090] like Figure 3 and Figure 4 As shown in FIG, the interface between the gas guide portion 200 and the lead film 190 is not normally open, and if the pressure inside the outer packaging material 110 increases, the interface between the gas guide portion 200 and the lead film 190 may open along the gas channel 240 to form a gas discharge path 250. The gas inside the outer packaging material 110 may move along the gas discharge path 250 on the gas channel 240 to the permeable portion 230, and in this case, an air pocket is formed in the permeable portion 230, so that the gas can be discharged to the outside of the outer packaging material 110 by passing through the lead film 190. As a result, the internal pressure of the outer packaging material 110 can be reduced to prevent the explosion or ignition of the secondary battery.

[0091] like Figure 3 and Figure 4 , the gas guide portion 200 of the present invention includes an adhesive resin layer 210 in contact with the electrode lead 180 and a permeable resin layer 220 provided on the adhesive resin layer 210. The adhesive resin layer 210 is in contact with the electrode lead 180 and can be used to adhere the gas guide portion 200 to the electrode lead 180.

[0092] like Figure 3 and Figure 4 , the gas guide portion 200 includes an adhesive resin layer 210 in contact with the electrode lead 180 and a permeable resin layer 220 disposed on the adhesive resin layer 210. The adhesive resin layer 210 is in contact with the electrode lead 180 and can be used to adhere the gas guide portion 200 to the electrode lead 180.

[0093] On the one hand, as in Figure 3 In the embodiment, the end portion of the adhesive resin layer 210 of the gas guide portion 200 in the outer direction E of the outer packaging material may be formed to be longer than the permeable resin layer 220. Therefore, a structure in which the adhesive resin layer 210 is in direct contact with the lead film 190 may be formed at the end portion of the gas guide portion 200 in the outer direction E.

[0094] Independently therefrom, the end portion of the lead film 190 protruding in the outer direction E of the outer package material may be provided to directly contact the electrode lead 180 by protruding further in the outer direction E than the end portion of the adhesive resin layer 210 in the same direction.

[0095] Furthermore, independently of this, the end portion of the lead film 190 protruding in the outer direction E of the outer package material may also be provided so as to protrude further in the outer direction E than the end portion of the permeable resin layer 220 in the same direction.

[0096] In the case where the adhesive resin layer 210 is formed to protrude more than the permeable resin layer 220 in the outer direction E of the outer packaging material, or in the case where the lead film 190 is formed to protrude more than the end of the permeable resin layer 220 and / or the adhesive resin layer 210 in the outer direction of the outer packaging material, the adhesion between the electrode lead 180 and the gas guide part 200 and the adhesion between the electrode lead 180 and the lead film 190 can be excellent, and therefore, since a reduction in durability due to an increase in internal pressure can be prevented and the area of ​​the permeable part 230 on the permeable resin layer 220 can be easily ensured, stable gas discharge can be achieved.

[0097] On the other hand, as in Figure 5 In the embodiment, one end portion of lead film 190 protruding in the outer direction E of the housing can be arranged to directly contact electrode lead 180 by protruding further than the end portion of gas guide portion 200 in the outer direction E of the housing. Independently of this, the ends of the two layers of gas guide portion 200 in the outer direction E can be formed to overlap.

[0098] On the other hand, as in Figure 6 In the embodiment, one end portion of the adhesive resin layer 210 protruding in the outer direction E of the housing further protrudes than the end portion of the permeable resin layer 220 in the outer direction E of the housing, but the end portion of the adhesive resin layer 210 in the outer direction E may be formed to coincide with the end portion of the lead film 190 in the outer direction E. In this case, the lead film 190 may have a structure in which the lead film 190 is not in direct contact with the electrode lead 180 but is in contact with the adhesive resin layer 210.

[0099] In such a Figure 3 、 Figure 5 or Figure 6In the case of the arrangement structure in which the lead film 190, the electrode lead 180, and the gas guide portion 200 are formed, compared with the case in which one end portion of the lead film 190 is not provided to protrude further to the outside of the outer packaging material 110 than the gas guide portion 200 but is provided on the permeable resin layer 220 of the gas guide portion 200, it may be advantageous in terms of ensuring durability and ensuring the area of ​​the permeable portion 230. However, although the lead film 190 may be most preferably provided as Figure 3 As in Figure 5 or Figure 6 There are no performance disadvantages in the structure, but there may be some differences in design and process.

[0100] Adhesive resin layer 210 may include any material that easily adheres to electrode lead 180. Specifically, adhesive resin layer 210 may include a modified polyolefin-based resin. When adhesive resin layer 210 includes a modified polyolefin-based resin, adhesion between gas guide portion 200 and electrode lead 180 is improved. Therefore, even when the pouch-type secondary battery is stored in a high-temperature environment, it is possible to prevent gas guide portion 200 from detaching from electrode lead 180 and being pushed out of the pouch, or leakage of electrolyte solution in the pouch.

[0101] The adhesive resin layer 210 may include at least one of acid-modified polyolefin and silane-modified polyolefin.

[0102] Acid-modified polyolefin refers to a polyolefin resin that has been graft-modified with an acid. For example, the acid-modified polyolefin can be a polyolefin into which a carboxyl group (graft-modified) is introduced by reacting an unsaturated carboxylic acid with a polyolefin resin. In this case, the unsaturated carboxylic acid can include the concept of a carboxylic anhydride, and the carboxyl group can include the concept of a carboxylic anhydride group. The unsaturated carboxylic acid reacted with the polyolefin resin can include at least one selected from the group consisting of maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitic acid, maleic anhydride, itaconic anhydride, glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornene dicarboxylic anhydride and tetrahydrophthalic anhydride, but is not limited thereto. Among them, maleic anhydride is preferably used to improve the bonding strength between the gas guide portion 200 and the electrode lead 180. The acid-modified polyolefin can include at least one selected from the group consisting of acid-modified polypropylene (PPa) and acid-modified polyethylene (PEa), but is not limited thereto.

[0103] Silane-modified polyolefin refers to a polyolefin resin that has been graft-modified with an unsaturated silane compound. The silane-modified polyolefin may have a structure in which an unsaturated silane compound is graft-copolymerized onto a polyolefin resin as a main chain. The silane-modified polyolefin-based resin may include at least one selected from the group consisting of a silane-modified polypropylene resin and a silane-modified ethylene-vinyl acetate copolymer, but is not limited thereto.

[0104] The adhesive resin layer 210 may be subjected to a modification process, and the modification process may include ion implantation, plasma treatment, radiation treatment, or heat treatment, and preferably a process that changes the bonding structure of the polymer layer. One type of these modification processes may be performed alone, or a combination of two or more types of these modification processes may be performed. The adhesive resin layer 210 subjected to the modification process may include plasma-treated polypropylene (PP), but is not limited thereto.

[0105] The thickness of the adhesive resin layer 210 may be in the range of 5 μm to 130 μm, particularly in the range of 30 μm to 120 μm, and more particularly in the range of 30 μm to 80 μm. In the case where the thickness of the adhesive resin layer 210 satisfies the above numerical range, since the adhesive resin layer 210 melts within a set tact time, the gas guide portion 200 and the electrode lead 180 can be easily welded.

[0106] The permeable resin layer 220 may be a layer in contact with the lead film 190 .

[0107] The permeable resin layer 220 may include at least one of polytetrafluoroethylene (PTFE) and polyimide (PI), but is not limited thereto. Preferably, the permeable resin layer 220 includes polyimide. In this case, since the adhesion between the permeable resin layer 220 and the lead film 190 is reduced, a gas exhaust path 250 can be formed when the internal pressure of the housing 110 increases.

[0108] The thickness of the permeable resin layer 220 may be in the range of 40 μm to 100 μm, particularly in the range of 40 μm to 90 μm, and more particularly in the range of 45 μm to 75 μm. When the thickness of the permeable resin layer 220 satisfies the above numerical range, the interface between the permeable resin layer 220 and the lead film 190 can be lifted when the internal pressure of the housing 110 rises and the permeable resin layer 220 does not melt during the sealing process, thereby forming a gas exhaust path 250.

[0109] The ratio (D1 / D2) of the thickness (D1) of the adhesive resin layer to the thickness (D2) of the permeable resin layer may be in the range of 0.4 to 2.0, particularly in the range of 0.4 to 1.5, and more particularly in the range of 0.4 to 1.0. In the case where the ratio (D1 / D2) satisfies the above numerical range, since the interface between the permeable resin layer 220 and the lead film 190 is lifted when the internal pressure of the housing 110 rises, the adhesive strength between the gas guide portion 200 and the electrode lead 180 can be improved while forming a gas discharge path.

[0110] The permeable resin layer 220 and the adhesive resin layer 210 may be laminated by heat compression, and may be laminated after forming an adhesive layer between the permeable resin layer 220 and the adhesive resin layer 210, or the permeable resin layer 220 and the adhesive resin layer 210 in the form of a tape with an adhesive applied to either surface and a release film attached thereto may be laminated after removing a release film. There is no particular limitation on the lamination method of the permeable resin layer 220 and the adhesive resin layer 210, and any method other than the method described above may be used as long as the two layers can be well adhered to each other.

[0111] (6) Enhanced membrane

[0112] According to an embodiment of the present invention, the reinforcement film 300 is characterized in that it plays a role in preventing whitening and electrolyte solution seepage by being provided on the lead film 190 to cover at least a portion of the permeation portion 230 of the gas guide portion 200 .

[0113] In the pouch-type secondary battery 100, gas is discharged through a series of mechanisms, in which, when the internal pressure increases, as the interface between the gas guide portion 200 and the lead film 190 opens, a gas discharge path 250 is formed by lifting up the stack including the lead film 190 and the outer packaging material 110 thereon only in the portion where the gas guide portion 200 is provided, and through the gas discharge path 250 thus formed, the internal gas is discharged to the outside through the lead film 190 of a portion of the permeable portion 230.

[0114] If this gas exhaust mechanism is repeated, the lead film 190 located in the portion through which gas passes, that is, the area of ​​the permeable portion 230 of the gas guide portion 200, is continuously subjected to a tensile force. Since the tensile force applied to the lead film 190 increases as the internal pressure increases, a whitening phenomenon may occur in the corresponding portion. Specifically, when the molecular structure in the lead film 190 is deformed due to the continuous stretching of the film, the internal pressure increases due to this deformation, and thus the bonding force between the molecules is weakened. The whitening phenomenon may occur in the portion where the bonding force between the molecules is weakened.

[0115] When the gas is exhausted and the internal pressure is reduced again, that is, when all the internal gas is exhausted due to the completion of a series of charge and discharge reactions and the battery is in a storage state, the gas exhaust path 250 is closed again while the lifted lead film 190 returns to its original state. Gas exhaust path 250 must be closed to minimize the possibility of the electrolyte solution leaking to the outside. However, as described above, a portion of the lead film 190 where the bonding force between molecules is weakened appears, and the electrolyte solution can penetrate through this portion. This may lead to the following problems: electrolyte solution seepage is observed in a portion of the permeation portion 230 of the gas guide portion 200 on the lead film 190, or in severe cases, leakage occurs. Once electrolyte solution seepage or leakage occurs, the possibility of moisture penetration from the outside increases significantly. In addition, if the above phenomenon is repeated, the electrode lead 180 may be corroded, and if the internal pressure increases, the lead film 190 may break around the portion where the bonding force is weakened.

[0116] Therefore, an object of the present invention is to solve the above-mentioned problems by introducing a reinforcement film 300 on the lead film 190. The reinforcement film 300 is located on the permeable portion 230 of the gas guide portion 200, which is a region through which gas permeates. Therefore, it is possible to ensure durability by suppressing the deterioration of the gas guide portion 200 and the lead film 190 due to continuous gas discharge.

[0117] Reference Figure 3 and Figure 4 The gas guide portion 200 is provided on the electrode lead 180, the lead film 190 is provided on the gas guide portion 200, and the reinforcement film 300 is provided on the lead film 190, and the reinforcement film 300 is provided on the surface of the lead film 190 exposed to the outside of the platform portion 150 of the outer packaging material 110. Figure 4 As shown in FIG, the gas exhaust path 250 is formed when the interface between the gas guide portion 200 and the lead film 190 is opened when the internal pressure increases, and as shown in FIG. Figure 7 In the embodiment, the permeation portion 230 of the gas guide portion 200 is provided at the outermost portion of the gas guide portion 200 located on the outer side of the platform portion 150, so that gas is discharged through the lead film 190 of this portion, and since the reinforcement film 300 is provided on the lead film 190 of the gas discharge portion, even if a continuous gas discharge action occurs, a whitening phenomenon or electrolyte solution seepage phenomenon caused by continuous stretching of the lead film 190 can be prevented, and therefore, durability can be improved.

[0118] In the reinforcement film 300, the area of ​​the reinforcement film 300 based on the circumference may be 100% to 500% of the area of ​​the permeation portion 230 of the gas guide portion 200. That is, the reinforcement film 300 may be provided to cover at least the entire area of ​​the permeation portion 230, and may be arranged to cover the area (S) based on the permeation portion 230. A ), preferably 400%, 350%, or 300%. As long as the reinforcement membrane 300 is designed to cover the entire area of ​​the permeable portion 230, there is no particular problem. However, since there may be disadvantages in design aspects such as the sealing process and the thickness of the platform portion after sealing, it is desirable to design the reinforcement membrane to meet the above range. In addition, in order to effectively suppress electrolyte solution leakage and prevent whitening caused by stretching, it is desirable to design the area of ​​the reinforcement membrane 300 to be greater than or equal to 110%, greater than or equal to 130%, or greater than or equal to 150% of the area of ​​the permeable portion 230.

[0119] Furthermore, when designing to cover the area of ​​the permeation portion 230 , the reinforcement membrane 300 may be provided so that a portion of the reinforcement membrane larger than the area of ​​the permeation portion 230 may also cover a portion of the gas channel 240 .

[0120] That is, considering the fact that the tensile force borne by the lead film 190 at the portion where the gas channel 240 meets the permeation portion 230 of the gas guide portion 200 is relatively large, in order to effectively prevent the whitening phenomenon and electrolyte solution leakage caused by stretching, when the area of ​​the reinforcement film is designed to be larger than the area of ​​the permeation portion 230 of the gas guide portion 200, it can be expected that the reinforcement film 300 is designed to be wider in the width direction of the electrode lead 180, and at the same time, the reinforcement film 300 is designed to be longer in the length direction of the electrode lead 180, and the reinforcement film can be preferably configured to cover not only the permeation portion 230 but also the gas channel 240, and in addition, the reinforcement film can be designed to extend to the portion adjacent to the sealing portion 151.

[0121] According to an embodiment of the present invention, Figure 8 and Figure 9 As illustrated in FIG, the reinforcement film 300 may have a hollow portion 301 formed therein, and the shape of the hollow portion in a plan view may be a rectangle ( Figure 8 ) or round ( Figure 9 The area of ​​the hollow portion 301 inside the reinforcement film 300, rather than its shape, has a greater influence on the protection of the lead film 190 or the gas discharge performance. In terms of ensuring the gas discharge area by the shape of the hollow portion 301, the shape that can ensure the optimal area can be appropriately selected in consideration of the specifications of the battery being designed or the configuration of the electrode assembly.

[0122] Specifically, the area of ​​the hollow portion 301 may be smaller than the area of ​​the permeation portion 230, and preferably, the area of ​​the hollow portion 301 is 50% to 90% of the area of ​​the permeation portion 230. The greatest expected effect of the shape of the hollow portion 301 is gas discharge performance, but in view of the fact that the expected effect of suppressing the whitening phenomenon and the electrolyte solution seepage phenomenon obtained by covering the reinforcement film 300 is also taken into consideration, it is preferable that the area of ​​the hollow portion 301 is appropriately designed at a level of 50% to 90% of the area of ​​the permeation portion as in the above range, and more preferably, the hollow portion 301 may be formed to have an area ranging from 50% to 85%, more preferably from 50% to 80%.

[0123] As described above, the hollow portion can have various shapes, but when designed as a rectangle, the length of the hollow portion in the protruding direction of the electrode lead can be designed to be smaller than the length of the permeable portion, and the width of the hollow portion in the width direction of the electrode lead can be designed to be smaller than the width of the permeable portion. As described with respect to the area of ​​the hollow portion 301, it is desirable that the width and length of the hollow portion 301 be designed in the same manner, wherein it is preferable to better design the width and length of the hollow portion by taking into account the fact that the length of the hollow portion in the longitudinal direction of the electrode lead is shorter than the length of the permeable portion.

[0124] In one aspect, the end portion of the reinforcement film 300 may extend in the inner direction I of the outer packaging material to be inserted between the lead film 190 and the outer packaging material 110 of a portion of the sealing portion 151, and may also extend to occupy a portion of the width of the sealing portion 151. In this case, the sealing strength can be improved, and accordingly, since the durability can be improved by maintaining the sealing strength even if the interface between the lead film 190 and the gas guide portion 200 is repeatedly opened, an unexpected gas discharge phenomenon can be prevented.

[0125] The sealing width (W S) can be in the range of 0.05 to 0.90. In the case where the insertion portion 301 is formed so that the length ratio satisfies the corresponding range, it is desirable to be able to ensure the advantage of sealing strength at a level that does not reduce the workability of the sealing process. That is, in the case where the reinforcing film 300 is deeply inserted into the sealing width so that the insertion portion (not shown) covers the entire sealing portion 151, since peeling will occur at the interface between the multilayer structured reinforcing films 300, the end portion of the reinforcing film 300 in the inner direction I of the outer packaging material only covers a part of the sealing width, allowing the sealing portion 151 to be covered, and therefore, the above-mentioned interface peeling problem can also be prevented. In order to further achieve this effect, preferably, the length ratio can be greater than or equal to 0.07, greater than or equal to 0.09, greater than or equal to 0.10, greater than or equal to 0.11, and can also be less than or equal to 0.85, less than or equal to 0.83, less than or equal to 0.80, less than or equal to 0.79, or less than or equal to 0.78.

[0126] On the one hand, the reinforcement film 300 may include at least one selected from the group consisting of a polyester-based resin, a polyolefin-based resin, a polyamide-based resin, and a polycarbonate-based resin. Preferably, the polyester-based resin may include polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), and may preferably include polyethylene naphthalate (PEN). In addition, the polyolefin-based resin may include polyethylene (PE), polypropylene (PP), or a resin modified with an acid or silicone, and unstretched cast polyolefin may also be used. In addition, nylon or polycarbonate may also be used. It is desirable to select the material of the reinforcement film by considering the tensile strength and gas barrier properties of the material, and it is also possible to select an appropriate material by considering whether a hollow portion of the reinforcement film will be formed.

[0127] In one aspect, the reinforcement film 300 may specifically have the following Figure 10 The two-layer structure or Figure 11 In the case where the reinforcement film 300 has a two-layer structure, the reinforcement film 300 may include a protective layer 310 and an adhesive layer 320 provided between the protective layer 310 and the lead film 190. In addition, in the case where the reinforcement film 300 has a three-layer structure, the reinforcement film 300 may include a protective layer 310, an adhesive layer 320 provided between the protective layer 310 and the lead film 190, and an insulating layer 330 provided on the protective layer 310 as the outermost surface.

[0128] As described above, the protective layer 310 may include at least one selected from the group consisting of polyester-based resins, polyolefin-based resins, polyamide-based resins, and polycarbonate-based resins, and the adhesive layer 320 and the insulating layer 330 may each independently include at least one selected from the group consisting of acid-modified polypropylene (PPa) and acid-modified polyethylene (PEa). In the case where acid-modified polypropylene or acid-modified polyethylene is used as the adhesive layer 320, the ability to maintain excellent durability is excellent due to excellent adhesion to the lead film 190, and in the case where acid-modified polypropylene or acid-modified polyethylene is used as the insulating layer 330, it can greatly contribute to the ability to prevent moisture from penetrating from the outside.

[0129] In this article, acid-modified polyolefin refers to a polyolefin resin that has been graft-modified with an acid. For example, the acid-modified polyolefin can be a polyolefin to which a carboxyl group (graft-modified) is introduced by reacting an unsaturated carboxylic acid with a polyolefin resin. The unsaturated carboxylic acid reacted with the polyolefin resin can include at least one selected from the group consisting of maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitic acid, maleic anhydride, itaconic anhydride, glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornene dicarboxylic acid, and tetrahydrophthalic anhydride, but is not limited thereto. Among them, maleic anhydride is preferably used to increase the bonding strength between the gas guide portion 200 and the electrode lead 180.

[0130] On the one hand, the reinforcement film 300 can be appropriately combined in the laminated structure and the hollow portion formation. In the case where the hollow portion 301 is formed in the reinforcement film 300, a two-layer structure or a three-layer structure can be used as the laminated structure of the reinforcement film 300. In the case where the hollow portion 301 is formed, since the minimum gas discharge area can be ensured, the gas discharge area can be ensured by the hollow portion 301, and the expected effect of the present invention can be achieved by performing the functions of suppressing the whitening phenomenon and suppressing the electrolyte solution leakage phenomenon outside the hollow portion 301 through the reinforcement film 300.

[0131] In the case where the hollow portion 301 is not formed in the reinforcement film 300, it is desirable not to use a three-layer structured reinforcement film 300. A two-layer structured reinforcement film 300 does not significantly reduce the gas discharge rate even if it covers the gas-permeable region, and even if the gas discharge rate is reduced, it is considered to have sufficient performance in maintaining battery performance and preventing swelling. However, since the gas discharge rate is significantly reduced when a three-layer structure is used, it is desirable to avoid a three-layer structure without a hollow portion when designing the reinforcement film 300.

[0132] Preferably, the reinforcement film may include an adhesive layer in contact with the lead film; and a protective layer disposed on the adhesive layer and containing a polyester-based resin, or the reinforcement film has a hollow portion formed therein, wherein the reinforcement film may include an adhesive layer in contact with the lead film; and a protective layer disposed on the adhesive layer and containing a polyester-based resin.

[0133] As another example, the reinforcement film has a hollow portion formed therein, wherein the reinforcement film may include an adhesive layer contacting the lead film; a protective layer disposed on the adhesive layer and including a polyester-based resin; and an insulating layer disposed on the protective layer.

[0134] (7) Electrolytes

[0135] The pouch-type secondary battery 100 according to the present invention may further include an electrolyte (not shown) injected into the outer packaging material 110. The electrolyte is used to move lithium ions generated by the electrochemical reaction of the electrodes during the charge / discharge of the secondary battery 100. The electrolyte may include a non-aqueous organic electrolyte solution that is a mixture of a lithium salt and an organic solvent, or a polymer electrolyte. In addition, the electrolyte may include a sulfide-based, oxide-based, or polymer-based solid electrolyte, and the solid electrolyte may have flexibility that allows it to be easily deformed by external force.

[0136] Hereinafter, the present invention will be described in detail based on specific examples. However, the following examples are provided only to illustrate the present invention, and the scope of the present invention is not limited thereto. It will be clear to those skilled in the art that various modifications and variations can be made within the scope and technical spirit of the present invention. Such modifications and variations fall within the scope of the claims included herein.

[0137] Examples and Comparisons

[0138] Example 1

[0139] (1) Preparation of outer packaging materials

[0140] A polyethylene terephthalate (PET) film having a width of 266 mm, a length of 50 m and a thickness of 12 μm and a nylon film having a width of 266 mm, a length of 50 m and a thickness of 25 μm are laminated on one surface of an aluminum alloy film having a width of 266 mm, a length of 50 m and a thickness of 60 μm, and a polypropylene film having a width of 266 mm, a length of 50 m and a thickness of 80 μm is laminated on the other surface of the aluminum alloy film to prepare a bag film laminate having a structure of polyethylene terephthalate / nylon / aluminum alloy film / polypropylene film.

[0141] Herein, the polyethylene terephthalate film and the nylon film are the base material layers, the aluminum alloy film is the gas barrier layer, and the polypropylene film is the sealant layer.

[0142] By forming the bag film laminate, an outer packaging material including a containing portion and a sealing portion is prepared.

[0143] (2) Preparation of pouch-type secondary batteries

[0144] The negative electrode, the positive electrode, and the porous polyethylene separator are assembled by a stacking method and then laminated to prepare an electrode assembly. Thereafter, an electrode lead is bonded to the electrode assembly.

[0145] The electrolyte was prepared by dissolving LiPF6 in a solvent (EC:EMC:DMC=3:3:4 volume ratio) so that the concentration of LiPF6 was 1.0 M. With the tip of the electrode lead pulled to the outside, the electrode assembly was housed in an outer packaging material and the electrolyte was injected.

[0146] A 50 μm thick polytetrafluoroethylene film (permeable resin layer) was attached to a 40 μm thick acid-modified polypropylene film (adhesive resin layer) on the upper surface of the electrode lead to form a gas guide portion.

[0147] Subsequently, a 200 μm thick lead film was stacked on each of the lower surface of the electrode lead and the upper surface of the gas guide portion. The lead film included a 75 μm thick metal adhesive layer made of copolymer polypropylene and acid-modified polypropylene, a 65 μm thick core layer made of homopolymer polypropylene, and a 60 μm thick bag adhesive layer made of copolymer polypropylene.

[0148] Finally, a reinforcement film was formed by sequentially laminating a 40 μm thick acid-modified polypropylene film and a 12 μm thick polyethylene naphthalate film on the upper surface of the lead film having the gas guide portion formed thereon, particularly on the upper surface of the permeation portion of the lead film having the gas guide portion formed thereon and located on the outside of the outer packaging material relative to the sealing position.

[0149] Hereinafter, under the conditions of a sealing strip area of ​​200 mm × 10 mm, 220° C., and 0.27 MPa, the sealing portion of the outer packaging material was sealed for 2 seconds and then left to stand at 60° C. for 4 hours to prepare a pouch-type secondary battery. In this case, the portion of the platform portion where the permeable portion of the gas guide portion was formed was formed to have a structure in which a lower case / lead film / electrode lead / gas guide portion / lead film / upper case were stacked in this order.

[0150] Example 2

[0151] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a hollow portion was formed in the reinforcement film and the area of ​​the hollow portion was 50% of the area of ​​the permeation portion of the gas guide portion.

[0152] Example 3

[0153] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a hollow portion was formed in the reinforcement film and the area of ​​the hollow portion was 75% of the area of ​​the permeation portion of the gas guide portion.

[0154] Example 4

[0155] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a 40 μm-thick acid-modified polypropylene film was additionally laminated on the upper surface of the polyethylene naphthalate film of the reinforcement film, and a hollow portion was formed with an area of ​​50% of the area of ​​the permeation portion of the gas guide portion.

[0156] Example 5

[0157] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a 40 μm-thick acid-modified polypropylene film was additionally laminated on the upper surface of the polyethylene naphthalate film of the reinforcement film, and a hollow portion was formed with an area of ​​75% of the area of ​​the permeation portion of the gas guide portion.

[0158] Example 6

[0159] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a 100 μm-thick polypropylene film was used instead of the polyethylene naphthalate film of the reinforcement film.

[0160] Example 7

[0161] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that a 200 μm-thick polypropylene film was used instead of the polyethylene naphthalate film of the reinforcement film.

[0162] Comparative Example 1

[0163] A pouch-type secondary battery was prepared in the same manner as in Example 1, except that the reinforcement film was not formed.

[0164] Test Example 1: Gas Emission Rate Measurement

[0165] For each of the pouch-type secondary batteries prepared in Examples 1 to 7 and Comparative Example 1, a gas discharge rate was measured.

[0166] Specifically, CO 2 was injected into the inside of the pouch-type secondary battery using a pressure-resistant device by ITS to increase the internal pressure of the pouch to 1.5 atm, and then the gas emission amount for 24 hours was measured, and the results are presented in Table 1 below.

[0167] Test Example 2: Measurement of the operating pressure of the gas guide section

[0168] For each of the pouch-type secondary batteries prepared in Examples 1 to 7 and Comparative Example 1, the operating pressure of the gas guide portion was measured.

[0169] Specifically, while increasing the internal pressure of the pouch in increments of 0.1 atm by injecting CO2 into the interior of the pouch-type secondary battery using a pressure-resistant device through an ITS, the pouch-type secondary battery was left standing at various pressures for 24 hours to measure the pressure when the permeable portion of the gas guide portion was completely deformed (a case where the entire permeable portion was lifted), and the results are presented in Table 1 below.

[0170] Test Example 3: Presence or absence of whitening phenomenon and electrolyte solution leakage

[0171] For each of the pouch-type secondary batteries prepared in Examples 1 to 7 and Comparative Example 1, within 24 hours after the internal pressure of the pouch was increased to 2.0 atm by injecting CO2 into the interior of the pouch-type secondary battery using a pressure-resistant device through an ITS, the whitening (stretching) phenomenon at the edge portion of the gas guide portion was calculated by the following Equation 1, and the presence of electrolyte solution seepage was confirmed.

[0172] [Equation 1]

[0173] Whitening phenomenon (%) = [length of whitening appearing on the lead film (mm)] / [total circumference of the gas guide portion (mm)]

[0174] [Table 1]

[0175]

[0176]

[0177] According to Table 2, for Examples 1 to 7, in which a reinforcement film was used on the upper surface of the lead film on the permeation portion of the gas guide portion, it was confirmed that while the gas discharge rate was maintained at an appropriate level, the degree of whitening was significantly reduced or did not occur at all, and no electrolyte solution seepage occurred. However, for Comparative Example 1, despite the high gas discharge rate, extremely severe whitening was confirmed, and electrolyte solution seepage occurred.

[0178] [Description of Reference Signs]

[0179] 100: Pouch-type secondary battery

[0180] 110: Outer packaging materials

[0181] 120: First shell

[0182] 122: cup-shaped part

[0183] 124: Accommodation

[0184] 130: Second shell

[0185] 132: cup-shaped part

[0186] 140: Bridging section

[0187] 150: Platform part

[0188] 151: Sealing part

[0189] 160: Electrode assembly

[0190] 170: Electrode tab

[0191] 172: Positive terminal

[0192] 174: Negative terminal

[0193] 180: Electrode lead

[0194] 182: Positive lead

[0195] 184: Negative lead

[0196] 190: Lead film

[0197] 200: Gas guide part

[0198] 210: Adhesive resin layer

[0199] 220: Permeable resin layer

[0200] 230: Penetration

[0201] 240: Gas channel

[0202] 250: Gas emission path

[0203] 300: Enhanced film

[0204] 301: Hollow part

[0205] 310: Protective layer

[0206] 320: Adhesive layer

[0207] 330: Insulation layer

Claims

1. A pouch-type secondary battery, comprising: electrode assembly; an outer packaging material, the outer packaging material including a receiving portion and a platform portion, the receiving portion receiving the electrode assembly, the platform portion being formed along a periphery of the receiving portion and having a sealing portion in which a portion of the width of the platform portion is sealed; an electrode lead electrically connected to the electrode assembly and protruding outside the outer packaging material; a lead film, the lead film being disposed between the electrode lead and the outer packaging material; a gas guide portion disposed between the electrode lead and the lead film and comprising a permeable portion disposed outside the outer packaging material and one or more gas channels extending from the permeable portion toward the electrode assembly via the sealing portion; as well as A reinforcement film is provided on the lead film to cover at least a portion of the permeation portion.

2. The pouch-type secondary battery according to claim 1, wherein Due to the increase in the internal pressure of the outer packaging material, the interface between the lead film and the gas guide portion is opened along the gas passage, thereby providing a gas exhaust path.

3. The pouch-type secondary battery according to claim 1, wherein The reinforcement film includes an insertion portion occupying a portion of the width of the sealing portion, The insertion portion is a region where one end portion of the reinforcement film is inserted between the outer packaging material of the sealing portion and the lead film by extending inwardly of the outer packaging material.

4. The pouch-type secondary battery according to claim 1, wherein The area of ​​the reinforced membrane based on the outer circumference is 100% to 500% of the area of ​​the permeation portion.

5. The pouch-type secondary battery according to claim 1, wherein The reinforcement film is provided on the lead film to cover a portion of the gas channel and an entire permeation portion of the gas guide portion.

6. The pouch-type secondary battery according to claim 1, wherein The reinforcement film has a hollow portion formed therein, Wherein, the area of ​​the hollow portion is smaller than the area of ​​the permeable portion.

7. The pouch-type secondary battery according to claim 1, wherein The reinforcement film has a hollow portion formed therein, The area of ​​the hollow portion is 50% to 90% of the area of ​​the permeable portion.

8. The pouch-type secondary battery according to claim 1, wherein The reinforcement film includes at least one selected from the group consisting of a polyester-based resin, a polyolefin-based resin, a polyamide-based resin, and a polycarbonate-based resin.

9. The pouch-type secondary battery according to claim 1, wherein The reinforcement film includes: an adhesive layer in contact with the lead film; and a protective layer disposed on the adhesive layer. The protective layer includes at least one selected from the group consisting of polyester-based resin, polyolefin-based resin, polyamide-based resin, and polycarbonate-based resin.

10. The pouch-type secondary battery according to claim 1, wherein The reinforcement film has a hollow portion formed therein, and The invention comprises: an adhesive layer, the adhesive layer being in contact with the lead film; a protective layer, the protective layer being arranged on the adhesive layer; and an insulating layer, the insulating layer being arranged on the protective layer. The protective layer includes at least one selected from the group consisting of polyester-based resin, polyolefin-based resin, polyamide-based resin, and polycarbonate-based resin.

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

12. The pouch-type secondary battery according to claim 11, wherein One end portion of the adhesive resin layer protruding in the outer direction of the outer packaging material protrudes further than one end portion of the permeable resin layer protruding in the outer direction of the outer packaging material.

13. The pouch-type secondary battery according to claim 11, wherein One end portion of the lead film protruding in the outer direction of the outer package material protrudes further than one end portion of the permeable resin layer protruding in the outer direction of the outer package material.

14. A battery pack comprising: a plurality of pouch-type secondary batteries; and a package member housing a secondary battery, Wherein, the pouch-type secondary battery comprises: electrode assembly; an outer packaging material, the outer packaging material including a receiving portion for receiving the electrode assembly and a platform portion, the platform portion being formed along a periphery of the receiving portion and having a sealing portion in which a portion of a width of the platform portion is sealed; an electrode lead electrically connected to the electrode assembly and protruding outside the outer packaging material; a lead film, the lead film being disposed between the electrode lead and the outer packaging material; a gas guide portion provided between the electrode lead and the lead film and including a permeable portion provided on the exterior of the outer packaging material and one or more gas channels extending from the permeable portion toward the electrode assembly via the sealing portion; and A reinforcement film is provided on the lead film to cover at least a portion of the permeation portion.

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