Pouch-type secondary battery

Abstract

The pouch-type secondary battery disclosed in the present specification comprises: an electrode assembly; an exterior material; and a lead assembly. The lead assembly comprises: an electrode lead; an adhesive film disposed on the electrode lead; a gas-guiding film covering at least a portion of the adhesive film and including a permeable portion disposed outward of the exterior material relative to the sealing portion, and including one or more gas flow paths extending from the permeable portion toward the accommodation portion through the sealing portion; and a lead film disposed between the adhesive film and the exterior material and in contact with the exterior material. In addition, the sealing portion has an openable / closable portion in which the gas flow path is located and which can be opened and closed in accordance with an increase in internal pressure, and has a closed portion in which the gas-guiding film is not disposed, wherein a step difference ratio (△T) between the closed portion and the openable / closable portion is 2.00% to 7.00%.

Description

Pouch-type secondary battery

[0001] This specification relates to a pouch-type secondary battery, and more specifically, to a pouch-type secondary battery comprising a gas-inducing film for discharging internal gas.

[0002]

[0003] Rechargeable batteries are used in a wide range of fields, including small products such as digital cameras, P-DVDs, MP3 players, mobile phones, PDAs, portable game devices, power tools, and E-bikes, as well as large products requiring high output such as electric vehicles and hybrid vehicles, and power storage devices and backup power storage devices that store surplus generated power or new and renewable energy. Types of rechargeable batteries include nickel-cadmium batteries, nickel-hydrogen batteries, lithium-ion batteries, and lithium-ion polymer batteries.

[0004] A secondary battery can be manufactured by housing an electrode assembly, in which a positive electrode, a negative electrode, and a separator interposed between them are alternately stacked, into a battery case, injecting an electrolyte, and then sealing the battery case. Secondary batteries are classified into pouch type and can type depending on the material of the case housing the electrode assembly. Among these, a pouch-type battery can be manufactured by forming a cup portion by press-forming a flexible pouch film laminate, housing the electrode assembly in the inner receiving space of the cup portion, and sealing the sealing portion.

[0005] In pouch-type secondary batteries, gas may be generated inside the pouch during high-temperature operation, overcharging, or short circuits. If the gas pressure inside the pouch increases, there is a problem of the pouch venting, leading to explosion or ignition.

[0006] Accordingly, research on various types of gas exhaust components is being conducted to address the aforementioned problems, and there is a continuously increasing need for gas exhaust components that simultaneously consider gas exhaust, external moisture penetration, and electrolyte leakage; gas exhaust components that withstand high internal pressure while maintaining low operating pressure; and furthermore, gas exhaust components with excellent durability.

[0007]

[0008] The present invention aims to solve the above-mentioned problems by providing a pouch-type secondary battery with excellent durability and excellent sealing strength, in which, in a secondary battery equipped with a reversible gas discharge means, a step difference is formed between the gas flow path and the sealing thickness of the other parts within a predetermined range when forming the sealing part, thereby allowing the gas discharge means to operate at an appropriate time so that gas discharge occurs smoothly.

[0009] Furthermore, the aim is to provide a long-life pouch-type secondary battery with excellent unit cost competitiveness and ensured safety by improving lifespan at a low cost through increased durability via the control of sealing thickness without affecting gas emission performance.

[0010]

[0011] [1] In one aspect of the present specification, an electrode assembly; an exterior material having a multilayer film structure including a metal layer, a receiving portion for housing the electrode assembly and a sealing portion formed along the perimeter so as to seal the receiving portion; A pouch-type secondary battery is provided, comprising: an electrode lead connected to the electrode assembly and protruding to the outside of the outer material via the sealing portion; an adhesive film disposed on the electrode lead; a gas induction film covering at least a portion of the adhesive film, comprising a permeable portion disposed in the direction of the outer material rather than the sealing portion and one or more gas passages disposed to extend from the permeable portion via the sealing portion toward the receiving portion; and a lead film disposed to contact the outer material between the adhesive film and the outer material, wherein the sealing portion has a partially closed portion where the gas passage is located and which can be opened or closed according to an increase in internal pressure, and a closed portion where the gas induction film is not disposed, and the step ratio (△T) defined by the following formula 1 is 2.00% to 7.00%.

[0012] [Equation 1]

[0013] △T = [(T O - T C ) / T C ] x 100

[0014] In the above Equation 1, T O is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned temporary closure part, and T C is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned closure.

[0015] [2] In the above [1], the step rate may be 2.20% to 6.50%.

[0016] [3] In the above [1] and / or [2], the pouch-type secondary battery may have the interface between the lead film and the gas-inducing film open at the closed portion when the internal pressure of the outer material increases.

[0017] [4] In at least one of [1] to [3] above, the pouch-type secondary battery may be such that when the internal pressure of the outer casing increases, the interface between the gas induction film and the lead film in the closed portion is opened, allowing gas to move to the permeable portion, and the gas is discharged through the lead film on the permeable portion.

[0018] [5] In at least one of [1] to [4] above, the total thickness (T of the closure) of the closure portion S ) may be 1060 μm to 1150 μm.

[0019] [6] In at least one of [1] to [5] above, the lead assembly of the closed portion may include a lower outer casing, a lower lead film, an electrode lead, an adhesive film, a gas induction film, an upper lead film, and an upper outer casing.

[0020] [7] In at least one of [1] to [6] above, the lead assembly of the closure may include a lower outer casing, a lower lead film, an electrode lead, an adhesive film, an upper lead film, and an upper outer casing.

[0021] [8] In at least one of [1] to [7] above, the adhesive film may have one end protruding outward from the exterior material protruding further than the one end of the gas induction film protruding outward from the exterior material.

[0022] [9] In at least one of [1] to [8] above, the lead film may have one end protruding outward from the outer casing that protrudes further than the one end of the gas induction film protruding outward from the outer casing.

[0023]

[0010] In another aspect of the present specification, a pouch-type secondary battery; and a packaging that accommodates the pouch-type secondary battery, wherein the pouch-type secondary battery comprises: an electrode assembly; a receiving portion that accommodates the electrode assembly; and a sealing portion formed along the periphery thereof to seal the receiving portion, and an outer material having a multilayer film structure including a metal layer; A battery pack is provided comprising: an electrode lead assembly; wherein the lead assembly comprises an electrode lead connected to the electrode assembly and protruding to the outside of the outer material via the sealing portion; an adhesive film disposed on the electrode lead; a gas induction film covering at least a portion of the adhesive film, comprising a permeable portion disposed in the direction of the outer material rather than the sealing portion and one or more gas passages disposed to extend from the permeable portion via the sealing portion toward the direction of the receiving portion; and a lead film disposed to contact the outer material between the adhesive film and the outer material, wherein the sealing portion has a partially closed portion where the gas passage is located and which can be opened or closed according to an increase in internal pressure, and a closed portion where the gas induction film is not disposed, and the step ratio (△T) defined by the following formula 1 is 2.00% to 7.00%.

[0024] [Equation 1]

[0025] △T = [(T O - T C ) / T C ] x 100

[0026] In the above Equation 1, T O is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned temporary closure part, and T C is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned closure.

[0027]

[0011] In another aspect of the present specification, an electric device comprising the aforementioned battery pack is provided.

[0028]

[0029] In one aspect of the present specification, a pouch-type secondary battery equipped with a reversible gas discharge means has the advantage of excellent durability, as it can secure a high level of sealing strength without affecting gas discharge performance by controlling the step difference in sealing thickness of the sealing portion, so that the gas discharge means operates at an appropriate time.

[0030] In another aspect of this specification, pouch-type secondary batteries can simultaneously achieve the conflicting goals of gas discharge performance and durability through a relatively simple means of sealing thickness control, thereby offering the advantages of excellent cost competitiveness, guaranteed safety, and improved lifespan characteristics.

[0031]

[0032] Figure 1 is an exploded assembly diagram of a pouch-type secondary battery.

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

[0034] Figure 3 is an example of a top view in direction B for part A of the box in Figure 2.

[0035] FIG. 4 is an example of a cross-sectional view showing the closed state of the temporary closure with respect to point O in FIG. 3.

[0036] FIG. 5 is an example of a cross-sectional view showing the closed portion in an open state with respect to point O in FIG. 3.

[0037] Figure 6 is an example of a cross-sectional view for point C in Figure 3.

[0038] FIG. 7 is another example of a cross-sectional view showing the closed state of the temporary closure with respect to point O of FIG. 3.

[0039] FIG. 8 is another example of a cross-sectional view showing the closed state of the temporary closure with respect to point O in FIG. 3.

[0040]

[0041] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0042] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning that is commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0043] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components in addition to the components mentioned.

[0044] In this specification, when a part is described as including a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0045] In this specification, the description "A and / or B" means A, or B, or A and B.

[0046] In this specification, "%" means weight percent unless otherwise explicitly indicated.

[0047]

[0048] The pouch-type secondary battery, battery pack, and electric device described in this specification include at least one of the technical configurations described below, and may include any combination of technically possible configurations among the technical configurations below.

[0049]

[0050] Pouch-type secondary battery

[0051] In one aspect, a pouch-type secondary battery may include: an electrode assembly; an outer material having a multilayer film structure including a metal layer, comprising a receiving portion for housing the electrode assembly and a sealing portion formed along the periphery thereof to seal the receiving portion; and a lead assembly.

[0052] The lead assembly may include an electrode lead connected to the electrode assembly and protruding to the outside of the exterior material via the sealing portion, an adhesive film disposed on the electrode lead, a gas induction film covering at least a portion of the adhesive film, comprising a permeable portion disposed in the direction of the exterior material outside the sealing portion, and one or more gas flow paths disposed to extend from the permeable portion via the sealing portion toward the receiving portion, and a lead film disposed to contact the exterior material between the adhesive film and the exterior material.

[0053] The sealing portion may have a temporary closure portion in which the gas flow path is located and which can be opened or closed according to an increase in internal pressure, and a closed portion in which the gas induction film is not disposed.

[0054] In addition, the above pouch-type secondary battery may be characterized by having a step rate (△T) defined by the following Equation 1 of 2.00% to 7.00%.

[0055] [Equation 1]

[0056] △T = [(T O - T C ) / T C ] x 100

[0057] In the above Equation 1, T O is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned temporary closure part, and T C is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned closure.

[0058]

[0059] First, the components of the pouch-type secondary battery are described in general terms with reference to the drawings.

[0060] FIG. 1 is an exploded assembly view of a pouch-type secondary battery (100), and FIG. 2 is a cross-sectional view of a sealed pouch-type secondary battery (100). In FIG. 2, some of the components of the pouch-type secondary battery (100) are omitted for ease of understanding. As shown in FIG. 1 and FIG. 2, the pouch-type secondary battery (100) includes an outer casing (110), an electrode assembly (160), and a lead assembly (not shown), and the lead assembly includes an electrode lead (180), a lead film (190), and a gas induction film (200).

[0061]

[0062] (1) Exterior materials

[0063] In one aspect, the exterior material (110) includes a receiving portion (124) for housing the electrode assembly (160) and a sealing portion (151) formed along the perimeter of the receiving portion (124) so ​​as to seal it, and the sealing portion (151) may be formed on a part of a terrace portion (150) formed along the perimeter of the receiving portion (124).

[0064] The above outer material (110) may be manufactured by forming a pouch film laminate so as to accommodate an electrode assembly (160) inside, having a multilayer film structure, and may include a metal layer within the multilayer film structure.

[0065] The above pouch film laminate may include a substrate layer, a gas barrier layer, and a sealant layer. In the pouch film laminate, the substrate layer, the gas barrier layer, and the sealant layer may be laminated sequentially.

[0066] The substrate layer is formed on the outermost layer of the pouch film laminate to protect the secondary battery from friction and collision with the outside. The substrate layer is made of a polymer and can electrically insulate the electrode assembly from the outside.

[0067] The substrate layer may be composed of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber. Preferably, the substrate layer may be composed of polyethylene terephthalate (PET), nylon, or a combination thereof having wear resistance and heat resistance.

[0068] The substrate layer may have a single film structure made of any one material. In contrast, the substrate layer may have a composite film structure formed by two or more materials forming separate layers.

[0069] The thickness of the substrate layer may be 5 μm to 50 μm, specifically 7 μm to 40 μm, more specifically 25 μm to 38 μm. When the thickness of the substrate layer satisfies the above range, the external insulation is excellent, and the overall thickness of the pouch is not thick, so the energy density relative to the volume of the secondary battery may be excellent.

[0070] The gas barrier layer is laminated between the substrate layer and the sealant layer to secure the mechanical strength of the pouch, block the entry of gases or moisture from outside the secondary battery, and prevent electrolyte leakage from inside the outer material, and may be a metal layer.

[0071] The gas barrier layer can be formed from a metal, specifically an aluminum alloy thin film. When a gas barrier layer is formed using an aluminum alloy thin film, it is possible to secure mechanical strength above a certain level, while also ensuring light weight, complementing electrochemical properties of the electrode assembly and electrolyte, and heat dissipation. The aluminum alloy thin film may include one or more metal elements other than aluminum (Al), for example, selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0072] The thickness of the gas barrier layer may be 40 μm to 100 μm, specifically 50 μm to 90 μm, more specifically 55 μm to 85 μm. When the thickness of the gas barrier layer satisfies the above range, the moldability and gas barrier performance are excellent when molding the cup portion.

[0073] The sealant layer is intended to completely seal the interior of the outer material by mutually thermally bonding at the sealing portion when the outer material housing the electrode assembly on the inside is sealed. To this end, the sealant layer may be formed from a material having excellent thermal bonding strength.

[0074] The sealant layer can be formed from a material having insulating, corrosion-resistant, and sealing properties. Specifically, since the sealant layer comes into direct contact with the electrode assembly and / or electrolyte on the inside of the exterior material, it can be formed from a material having insulating and corrosion-resistant properties. In addition, since the sealant layer must completely seal the interior of the exterior material to block material transfer between the inside and outside, it can be formed from a material having high sealing properties (e.g., excellent thermal bonding strength). To ensure these insulating, corrosion-resistant, and sealing properties, the sealant layer can be formed from a polymer material.

[0075] The sealant layer may be composed of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber, and preferably may be composed of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may be composed of cast polypropylene (CPP), acid-modified polypropylene (PPA), polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene terpolymer.

[0076] The thickness of the sealant layer may be 30 μm to 130 μm, specifically 50 μm to 120 μm, and more specifically 70 μm to 100 μm. When the thickness of the sealant layer satisfies the above range, it has the effect of ensuring the sealing strength of the sealing portion while also ensuring the moldability of the pouch film laminate.

[0077]

[0078] The pouch film laminate can be drawn and stretched by a punch or the like to manufacture an outer material (110). As a result, the outer material (110) may include a cup portion (122) and a receiving portion (124). The receiving portion (124) is a place for receiving an electrode assembly and may refer to a receiving space formed in the shape of a pocket inside the cup portion (122) as the cup portion (122) is formed.

[0079] In one aspect, the outer casing (110) may include a first case (120) and a second case (130) as shown in FIG. 1. The first case (120) includes a receiving portion (124) capable of receiving an electrode assembly (160), and the second case (130) may cover the receiving portion (124) from above so that the electrode assembly (160) does not escape 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 FIG. 1, but are not limited thereto and may be manufactured in various ways, such as being separated from each other and manufactured separately.

[0080] In another aspect, when forming cup portions in a pouch film laminate, two symmetrical cup portions (122, 132) can be drawn and formed adjacent to each other in a single pouch film laminate. In this case, cup portions (122, 132) can be formed in the first case (120) and the second case (130) respectively, as shown in FIG. 1. After receiving an electrode assembly (160) in a receiving portion (124) provided in the cup portion (122) of the first case (120), a bridge portion (140) formed between the two cup portions (122, 132) can be folded so that the two cup portions (122, 132) face each other. In this case, the cup portion (132) of the second case (130) can receive the electrode assembly (160) from above. Accordingly, since two cup portions (122, 132) accommodate one electrode assembly (160), an electrode assembly (160) with a thicker thickness than when there is only one cup portion (122) can be accommodated. Additionally, since one corner of the secondary battery (100) is formed by folding the outer material (110), the number of corners to be sealed can be reduced when performing a sealing process later. Accordingly, the process speed of the pouch-type secondary battery (100) can be improved and the number of sealing processes can be reduced.

[0081] The outer material (110) can be sealed while accommodating the electrode assembly (160) so that a part of the electrode lead (180), which will be described later, i.e., the terminal part, 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 part of the electrode lead (180), the electrode assembly (160) is accommodated in the receiving portion (124) provided in the cup portion (122) of the first case (120), and the second case (130) can cover the receiving portion (124) from above. Subsequently, an electrolyte is injected into the interior of the receiving portion (124), and a part of the terrace portion (150) formed along the perimeter of the first case (120) and the second case (130) is sealed to form a sealing portion (151).

[0082] The sealing portion (151) can perform the function of sealing the receiving portion (124). Specifically, the sealing portion (151) can seal the receiving portion (124) by being formed on at least a part of the terrace portion (150) formed on the edge along the perimeter of the receiving portion (124).

[0083] The temperature for sealing the sealing portion (151) may be 180°C to 250°C, specifically 200°C to 250°C, more specifically 210°C to 240°C. When the sealing temperature satisfies the above numerical range, the exterior material (110) can secure sufficient sealing strength by thermal bonding.

[0084]

[0085] (2) Electrode assembly

[0086] In one aspect, the electrode assembly (160) can be inserted into the outer casing (110) and sealed by the outer casing (110) after the electrolyte is injected.

[0087] The electrode assembly (160) may be formed by sequentially stacking an anode, a separator, and a cathode. Specifically, the electrode assembly (160) may include two types of electrodes, an anode and a cathode, and a separator interposed between the electrodes to insulate them from one another.

[0088] The positive and negative electrodes may each have a structure in which an active material slurry is coated onto an electrode current collector in the form of a metal foil or metal mesh containing aluminum and copper. The slurry can typically be formed by stirring granular active material, an auxiliary conductor, a binder, and a conductive material with added solvent. The solvent can be removed in a subsequent process.

[0089] An electrode assembly (160) can be manufactured in a predetermined shape by applying a slurry, which is a mixture of an electrode active material and a binder and / or a conductive material, to an anode current collector and a cathode current collector to manufacture an anode and a cathode, and stacking them on both sides of a separator. The types of electrode assemblies (160) may include stack type, jelly roll type, stack and folding type, etc., but are not limited thereto.

[0090] The electrode assembly (160) may include an electrode tab (170).

[0091] The electrode tab (170) is connected to the positive and negative electrodes of the electrode assembly (160), respectively, and protrudes outward from the electrode assembly (160), serving as a path for electrons to move between the inside and outside of the electrode assembly (160). The electrode current collector included in the electrode assembly (160) may be composed of a portion coated with an electrode active material and a terminal portion not coated with an electrode active material, i.e., a non-coated portion. The electrode tab (170) may be formed by cutting the non-coated portion or by connecting a separate conductive member to the non-coated portion using ultrasonic welding or the like. As shown in FIG. 1, the electrode tab (170) may protrude in different directions from the electrode assembly (160), but is not limited thereto and may be formed to protrude in various directions, such as protruding in parallel from one side in the same direction.

[0092]

[0093] (3) Lead assembly

[0094] In one aspect, the pouch-type secondary battery may include a lead assembly comprising: an electrode lead connected to the electrode assembly and protruding to the outside of the outer casing via the sealing portion; an adhesive film disposed on the electrode lead; a gas induction film covering at least a portion of the adhesive film, comprising a permeable portion disposed in the direction of the outer casing rather than the sealing portion, and one or more gas flow paths disposed to extend from the permeable portion in the direction of the receiving portion via the sealing portion; and a lead film disposed to contact the outer casing between the adhesive film and the outer casing.

[0095]

[0096] electrode leads

[0097] In one aspect, the electrode lead (180) can supply electricity to the outside of the pouch-type secondary battery (100). The electrode lead (180) can be connected to the electrode tab (170) of the electrode assembly (160) by spot welding or the like.

[0098] The electrode lead (180) is connected to the electrode assembly (160) and can protrude to the outside of the exterior material (110) via the sealing portion (150). Specifically, one end of the electrode lead (180) is connected to the electrode assembly (160), specifically the electrode tab (170), and the other end of the electrode lead (180) can protrude to the outside of the exterior material (110) via the terrace portion (150).

[0099] The electrode lead (180) may include a positive lead (182) that has one end connected to a positive tab (172) and extends in the direction in which the positive tab (172) protrudes, and a negative lead (184) that has one end connected to a negative tab (174) and extends in the direction in which the negative tab (174) protrudes. Both the positive lead (182) and the negative lead (184) may have their other ends protruding to the outside of the battery case (110). Thus, electricity generated inside the electrode assembly (160) can be supplied to the outside. Additionally, since the positive tab (172) and the negative tab (174) are each formed to protrude in various directions, the positive lead (182) and the negative lead (184) may also each extend in various directions. The positive lead (182) and the negative lead (184) may have different materials. That is, the positive lead (182) is made of the same aluminum (Al) material as the positive current collector, and the negative lead (184) may be made of the same copper (Cu) material as the negative current collector or a copper material coated with nickel (Ni). A portion of the electrode lead (180) protruding outside the battery case (110) can be a terminal portion and electrically connected to an external terminal.

[0100] One side of the electrode lead (180) that is in direct contact with the lead film (190) and / or adhesive film (210) may be coated with one or more selected from the group consisting of chromium (Cr), nickel (Ni), aluminum oxide (Al2O3), zirconium (Zr)-based anhydride salts and titanium (Ti)-based anhydride salts. In this case, corrosion resistance to the electrolyte and adhesion to the lead film (190) and / or adhesive film (210) can be ensured.

[0101]

[0102] Lead film

[0103] In one aspect, the lead film (190) prevents electricity generated from the electrode assembly (160) from flowing through the electrode lead (180) to the battery case (110) and can maintain the sealing of the battery case (110). To this end, the lead film (190) may be formed of a non-conductive insulating material that does not conduct electricity well. Generally, the lead film (190) is often made of insulating tape that is easy to attach to the electrode lead (180) and / or gas induction film (220) and is relatively thin, but is not limited thereto, and any material capable of insulating the electrode lead (180) may be used.

[0104] The lead film (190) may be positioned to wrap around the outer surface of the electrode lead (180) and / or gas induction film (220). Specifically, the electrode lead (180) and / or gas induction film (220) may be in contact with each other on one side, and the electrode lead (180) and gas induction film (220) may be surrounded by the lead film (190). The lead film (190) may be positioned in a sealing portion (151) where the first case (120) and the second case (130) of the outer material (110) are heat-fused, and the electrode lead (180) and gas induction film (220) may be adhered to the outer material (110).

[0105] A lead film (190) may be placed between the electrode lead (180) and / or gas induction film (220) and the outer casing (110). For example, as shown in FIG. 2, a lower case (110), a lead film (190), an electrode lead (180), an adhesive film (210), a gas induction film (220), a lead film (190), and an upper case (110) may be arranged in a stacked state in order in the terrace portion (150).

[0106]

[0107] Meanwhile, the lead film (190) may include one or more layers. Specifically, the lead film (190) may include a sequentially laminated metal adhesive layer, a core layer, and a pouch adhesive layer.

[0108] The metal adhesive layer is in direct contact with the electrode lead (180) and may be intended to adhere the lead film (190) to the electrode lead (180). The metal adhesive layer may include any material that facilitates adhesion to the electrode lead (180). Specifically, the metal adhesive layer may include a modified polyolefin-based resin, for example, an acid-modified polyolefin. For example, the metal adhesive layer may include at least one of acid-modified polypropylene (PPa), acid-modified polyethylene (PEa), and plasma-treated polypropylene, but is not limited thereto. The thickness may be 50 μm to 80 μm, specifically 50 μm to 75 μm, more specifically 60 μm to 75 μm. When the thickness of the metal adhesive layer satisfies the above numerical range, it has the effect of preventing through-type pinholes and leaks at the edge portion when fusing between the electrode lead and the lead film.

[0109] The above acid-modified polyolefin refers to a polyolefin resin that has been graft-modified with acid. For example, the acid-modified polyolefin may be one in which a carboxyl group is introduced (graft-modified) by reacting an unsaturated carboxylic acid with a polyolefin resin. 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 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 acid, aconitic acid, norbornendicarboxylic acid anhydride, and tetrahydrophthalic acid anhydride, but is not limited thereto.

[0110] The core layer may be a layer located in the center of the lead film (190). The core layer may include an unmodified polyolefin resin, and may include, for example, polypropylene resin, polyolefin elastomer (POE), and / or additives such as coloring agents, but is not limited thereto. Among these, the core layer may include, for example, a polypropylene homopolymer. When a polypropylene homopolymer is included in the core layer, the melting point of the core layer can be controlled to the above numerical range and deformation caused by heat can be minimized, which is advantageous in terms of securing 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 caused by heat applied during fusion and sealing is prevented, thereby providing a robust design effect in terms of securing insulation.

[0111] The pouch adhesive layer may be a layer that comes into direct contact with the battery case (110), specifically the sealant layer of the pouch film laminate. The pouch adhesive layer may include an unmodified polyolefin resin, for example, a polypropylene resin, a polyolefin elastomer (POE), but is not limited thereto. Among these, the pouch adhesive layer may include a polypropylene copolymer, such as a polypropylene random copolymer or a polypropylene block copolymer. The melting point of the pouch adhesive layer containing such a copolymer can be controlled to the above numerical range and has a melting point similar to that of the polymer in the sealant layer of the pouch film laminate, which 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, more specifically 40 μm to 60 μm. When the thickness of the pouch adhesive layer satisfies the above numerical range, it has the effect of securing a polymer (e.g., polypropylene) residual rate sufficient to ensure strength during sealing between the electrode lead and the pouch film laminate.

[0112]

[0113] Adhesive film and gas induction film

[0114] In one aspect, the gas induction film (220) is provided to discharge gas from inside the outer material (110) to the outside. As shown in FIG. 2, the gas induction film (220) may be placed on at least a portion of the adhesive film (210) between the electrode lead (180) and the lead film (190) while the adhesive film (210) is attached to the electrode lead (180). In this case, among the areas between the adhesive film (210) and the lead film (190) placed on the electrode lead (180), the adhesive film (210) and the lead film (190) do not come into direct contact in the area where the gas induction film (220) is placed, and the adhesive film (210) and the lead film (190) can come into direct contact in the area where the gas induction film (220) is not placed. Accordingly, when a portion of the terrace portion (150) is sealed to form a sealing portion (151), the portion where the adhesive film (210) and the lead film (190) do not come into direct contact with the gas induction film (220) may form a partially closed portion that can be opened, for example, as the internal pressure of the exterior material rises, and the portion where the adhesive film (210) and the lead film (190) come into direct contact may form a closed portion.

[0115] Hereinafter, the adhesive film (210) and the gas induction film (220) will be described in more detail with reference to FIGS. 3 to 6. FIG. 3 is a top perspective view of a lead assembly portion showing a closed portion (c) and a partially closed portion (O) of the gas induction film (220); FIG. 4 is a cross-sectional view of a pouch-type secondary battery with respect to the partially closed portion (O) before the interface between the gas induction film (220) and the lead film (190) is opened; FIG. 5 is a cross-sectional view of a pouch-type secondary battery with respect to the partially closed portion (O) after the interface between the gas induction film (220) and the lead film (190) is opened; and FIG. 6 is a cross-sectional view of a pouch-type secondary battery with respect to the closed portion (C).

[0116] As shown in FIGS. 4 and 6, the interface between the gas induction film (220) and the lead film (190), that is, the partially closed part corresponding to point O in FIG. 3 and the closed part corresponding to point C, can be kept in a state where they are not open under normal circumstances.

[0117] When the internal pressure of the exterior material (110) increases, as shown in FIG. 5, the interface between the gas induction film (200) of the temporary closure (O) and the lead film (190) is opened, and the closure (C), unlike the temporary closure (O), is not opened and maintains a closed state as shown in FIG. 6, thereby forming a gas discharge path (300) in the gas flow path (222) and forming a gas pocket on the permeable part (221) of the gas induction film (220). The gas inside the exterior material (110) can move along the gas flow path (222) and then pass through the lead film (190) on the permeable part (221) to be discharged to the outside of the exterior material (110). As a result, the internal pressure of the exterior material (110) is lowered, thereby preventing the explosion or ignition of the exterior material (110).

[0118]

[0119] As illustrated in FIGS. 4 and 5, the gas induction film (220) may be placed on an adhesive film (210) that contacts the electrode lead (180). The adhesive film (210) contacts the electrode lead (180) and may be for attaching the gas induction film (220) to the electrode lead (180).

[0120] In one aspect, as shown in FIG. 4, the adhesive film (210) may be formed with a longer end in the outer direction (E) of the case than the gas induction film (220). Accordingly, at the outer direction (E) end of the adhesive film (210), a structure may be formed in which the adhesive film (210) comes into direct contact with the lead film (190).

[0121] Independently, the end of the lead film (190) protruding outwardly (E) of the case may be positioned to protrude further outwardly (E) than the end of the adhesive film (210) in the same direction so as to be in direct contact with the electrode lead (180).

[0122] When the adhesive film (210) is formed to protrude further outward (E) of the case than the gas induction film (220), or when the lead film (190) is formed to protrude further outward than the gas induction film (220) or one end of the gas induction film (220) and the adhesive film (210) in the outer direction of the outer material (110), the adhesion between the electrode lead (180) and the adhesive film (210), and between the electrode lead (180) and the lead film (190) may be excellent, thereby preventing a decrease in durability due to an increase in internal pressure, and making it easy to secure the area of ​​the permeable portion (221) on the gas induction film (220), so that stable gas discharge may be possible.

[0123] In another aspect, as shown in FIG. 7, the lead film (190) may be positioned so that one end protruding in the case-outward direction (E) protrudes further than the case-outward direction (E) end of the adhesive film (210) and the gas induction film (220) and comes into direct contact with the electrode lead (180). Independently, the case-outward direction (E) ends of the gas induction film (220) and the adhesive film (210) may be formed to coincide.

[0124] In another aspect, as shown in FIG. 8, the adhesive film (210) may be formed such that one end protruding in the case-outward direction (E) protrudes further than the case-outward direction (E) end of the gas induction film (220), and the case-outward direction (E) end of the adhesive film (210) coincides with the case-outward direction (E) end of the lead film (190). In this case, the lead film (190) may have a structure in which it contacts the adhesive film (210) rather than directly contacting the electrode lead (180).

[0125] When the arrangement structure of the lead film (190), electrode lead (180), adhesive film (210), and gas induction film (220) is formed as in FIG. 4, FIG. 7, or FIG. 8, it may be advantageous in terms of securing durability and securing the area of ​​the transparent portion (221) compared to the case where the lead film (190) is not arranged so that one end protrudes further outward from the outer surface of the outer material (110) than the gas induction film (220), however, most preferably it may be arranged as in FIG. 4, but depending on the case, the structure of FIG. 7 or FIG. 8 may also be applied, and any structure may be selectively applied.

[0126]

[0127] The adhesive film (210) may include any material that facilitates adhesion with the electrode lead (180). For example, the adhesive film (210) may include a modified polyolefin-based resin and may include at least one of an acid-modified polyolefin and a silane-modified polyolefin. When the adhesive film (210) includes a modified polyolefin-based resin, the adhesion between the gas induction film (200) and the electrode lead (180) is improved, so that even when the pouch-type secondary battery is stored in a high-temperature environment, the problem of the gas induction film (200) being detached from the electrode lead (180) and pushed outward from the pouch or the electrolyte inside the pouch leaking out can be prevented.

[0128] The above acid-modified polyolefin refers to a polyolefin resin that has been graft-modified with acid. For example, the acid-modified polyolefin may be one in which a carboxyl group is introduced (graft-modified) by reacting an unsaturated carboxylic acid with a polyolefin resin. 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 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 acid, aconitic acid, norbornendicarboxylic acid anhydride, and tetrahydrophthalic acid anhydride, but is not limited thereto. Among these, it is preferable to apply maleic anhydride to improve the adhesion strength between the gas induction film (200) and the electrode lead (180). The acid-modified polyolefin may include one or more selected from the group consisting of acid-modified polypropylene (PPa) and acid-modified polyethylene (PEa), but is not limited thereto.

[0129] The above silane-modified polyolefin refers to a polyolefin resin 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 that is the main chain. The silane-modified polyolefin resin may include one or more selected from the group consisting of silane-modified polypropylene resin and silane-modified ethylene-vinyl acetate copolymer, but is not limited thereto.

[0130] The adhesive film (210) may be modified, and the modification treatment may include ion implantation, plasma treatment, radiation treatment, heat treatment, etc., and a treatment that changes the bonding structure of the polymer layer is preferred. These modification treatments may be performed by carrying out one type alone, but may also be carried out by combining two or more types. The modified adhesive film (210) may include plasma-treated PP (plasma-treated polypropylene), but is not limited thereto.

[0131] The thickness of the adhesive film (210) may be 5 μm to 130 μm, specifically 30 μm to 120 μm, more specifically 30 μm to 80 μm. When the thickness of the adhesive film (210) satisfies the above numerical range, the adhesive film (210) melts within a set production time (tact time), thereby allowing the gas induction film (220) and the electrode lead (180) to be easily fused.

[0132]

[0133] The gas induction film (220) may be a layer in contact with the lead film (190). The gas induction film (220) may include one or more of polytetrafluoroethylene (PTFE) and polyimide (PI). The gas induction film (220) is preferred in that it does not have high adhesion to the lead film (190), so even if the part is sealed, the interface with the lead film (190) can be opened when the pressure inside the case (110) rises, thereby forming a gas discharge path (300).

[0134] The above gas induction film (220) can be designed to allow gas generated inside the outer casing to be discharged to the outside due to the fact that its adhesion to the lead film (190) is not high, and this characteristic also exerts the same effect in the adhesion to the electrode lead (180). Accordingly, since the adhesion to the electrode lead (180) is also poor, it may be necessary to place an adhesive film (210) between the gas induction film (220) and the electrode lead (180) as described above.

[0135] The thickness of the gas induction film (220) may be 40 μm to 100 μm, specifically 40 μm to 90 μm, more specifically 45 μm to 75 μm. When the thickness of the gas induction film (220) satisfies the above numerical range, the gas induction film (220) does not melt during the sealing process, and when the internal pressure of the case (110) rises, the interface between the gas induction film (220) and the lead film (190) opens, thereby forming a gas discharge path (250).

[0136]

[0137] Meanwhile, the ratio (D1 / D2) of the thickness (D2) of the adhesive film to the thickness (D1) of the gas induction film (220) may be 0.4 to 2.0, specifically 0.4 to 1.5, more specifically 0.4 to 1.0. When the ratio (D1 / D2) satisfies the above numerical range, when the internal pressure of the case (110) rises, the interface between the permeable resin layer (220) and the lead film (190) is lifted to form a gas discharge path, while the adhesive strength between the gas induction film (200) and the electrode lead (180) can be improved.

[0138] The gas induction film (220) and the adhesive film (210) may be laminated through heat pressing and then placed on the electrode lead (180), or they may be placed after forming an adhesive layer between them and laminating them, or the gas induction film (220) or the adhesive film (210) may be in the form of a tape with an adhesive applied to one side and a release film attached, and then laminated after removing the release film and placed on the electrode lead (180). There are no particular limitations on the method of laminating the permeable resin layer (220) and the adhesive film (210), and any method that allows the two layers to adhere well to each other may be applied in addition to the method described above.

[0139]

[0140] Step ratio (△T)

[0141] In one aspect, the pouch-type secondary battery is characterized by having a step difference rate (△T) defined by the following formula 1 of 2.00% to 7.00%, wherein the step difference rate refers to a ratio derived from the difference in sealing thickness between the closed portion (C) and the partially closed portion (O) formed on the sealing portion.

[0142] Referring to FIGS. 3 to 5, the sealing portion (151) has a provisional closed portion (O) in which the gas passage (222) is located and which can be opened or closed as the internal pressure rises, and a closed portion (C) in which the gas inducing film (220) is not placed, in an area excluding the provisional closed portion. At this time, it is preferable to seal such that the step difference rate of the total thickness after sealing the closed portion (C) and the provisional closed portion (O) is 2.00% to 7.00%.

[0143] In the case of pouch-type secondary batteries equipped with a gas discharge mechanism, there is a problem in that it is very difficult to design the battery in a way that improves the performance of both due to conflicting issues regarding sealing performance, given that the design ensures continuous gas discharge.

[0144] The above pouch-type secondary battery (100) has a series of mechanisms in which, when the internal pressure rises, the interface between the gas induction film (220) and the lead film (190) is opened, and the laminates including the lead film (190) and the outer casing (110) above it are lifted upward only in the portion where the gas induction film (200) is placed, thereby forming a gas discharge path (300) along the gas flow path (222), and the internal gas is discharged to the outside by passing through the lead film (190) of the permeable portion (221) through the gas discharge path (300) thus formed.

[0145] If this gas discharge mechanism is repeated, the lead film (190) in the gas flow path (222) region of the gas induction film (220), for example, the closed portion (O), and the surrounding region, for example, the closed portion (C), will be continuously subjected to tension, and as the internal pressure increases, the tension received by the lead film (190) will increase, causing the relevant portion to lose its sealing power and peel off, or the electrolyte to leak, or the gas to be irreversibly ejected from the relevant portion, resulting in a vent that ends the life of the battery.

[0146] However, the above pouch-type secondary battery (100) is designed to satisfy the step difference ratio that controls the step difference between the sealing thickness of the openable / closed portion and the sealing thickness of the closed portion by installing a gas flow path formed in the sealing portion. This ensures that even if the openable / closed portion is repeatedly opened and closed due to reversible and continuous gas discharge, the sealing force of the surrounding closed portion is strongly maintained, thereby providing excellent durability while ensuring gas discharge performance and safety.

[0147] Accordingly, the above pouch-type secondary battery is characterized by having a step rate defined by the following formula 1 of 2.00% to 7.00%.

[0148] [Equation 1]

[0149] △T = [(TO - T C ) / T C ] x 100

[0150] In the above Equation 1, T O is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned temporary closure part, and T C is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned closure.

[0151] Preferably, the above pouch-type secondary battery may have a step rate of 2.20% or more, 2.40% or more, 2.60% or more, 2.70% or more, 2.80% or more, 2.90% or more, or 3.00% or more, and may also have a step rate of 6.50% or less, 6.00% or less, 5.70% or less, 5.50% or less, 5.30% or less, 5.00% or less, 4.80% or less, or 4.50% or less.

[0152] When the above step ratio satisfies the range described above, as previously mentioned, it is possible to improve sealing strength without affecting gas discharge performance, thereby having the advantage of improving all conflicting problems. For example, if the above step ratio exceeds 7.00%, although the opening of the gas flow path can be easily achieved, there is a disadvantage that the sealing thickness of the closed part is too thin, resulting in very poor sealing strength. In particular, the decrease in sealing strength at high temperatures is pronounced, and the sealing power is easily lost even at temperatures where battery operation is sustainable, resulting in poor durability. Furthermore, if the above step ratio is less than 2.00%, the closed part does not open at internal pressures below a certain level, so gas discharge begins only after excessive swelling of the battery occurs, making it difficult to see the effect of gas discharge. This problem becomes more pronounced at high temperatures, leading to a problem where the sealing strength at high temperatures deteriorates.

[0153] The above step ratio can be calculated by excluding the thickness of the layer containing a metal component as a material in the partially closed and closed parts of the lead assembly. For example, the thickness of the metal layer included as a gas barrier layer of the outer material and the electrode lead in the laminated structure of the lead assembly can be excluded. In the case of the metal layer, unlike layers of resin components, its thickness does not decrease even when a sealing process is performed, and since it can act as noise when calculating the sealing thickness to determine whether sealing strength is secured through sealing, it may be desirable to exclude it from the calculation.

[0154] The above step ratio can be achieved by performing sealing with different forces on the partially closed portion where the gas passage is located and the closed portion, which is the other area, during the process of forming a sealing portion in the lead assembly portion. The greater the force applied during sealing, the thinner the sealing thickness (thickness after sealing) becomes, and if the sealing thickness is thin, the sealing strength may decrease. However, even if the force applied during sealing is insufficient, the bonding force between the laminates constituting the lead assembly may be weak, which may result in a problem of reduced sealing strength. Furthermore, in the case of the pouch-type secondary battery equipped with a gas discharge means in the lead assembly, if the appropriate level is not found, there is a disadvantage that the operating pressure at which gas discharge begins may increase.

[0155] Accordingly, it is desirable to control the step ratio by adjusting the sealing thickness to be thin by sealing the provisional closing portion strongly to allow for better opening in consideration of the operating pressure during sealing, and by adjusting the sealing thickness to be thick by sealing the closed portion relatively weakly to increase durability by maintaining the overall airtightness of the pouch-type secondary battery.

[0156] In one aspect, the lead assembly of the above-mentioned temporary closure may include a lower outer layer, a lower lead film, an electrode lead, an adhesive film, a gas induction film, an upper lead film, and an upper outer layer, and the lead assembly of the above-mentioned closure may include a lower outer layer, a lower lead film, an electrode lead, an upper lead film, and an upper outer layer. For example, the lead assembly of the above-mentioned closure may further include an adhesive film among the constituent laminates of the gas induction film between the electrode lead and the upper lead film.

[0157] The thickness excluding the metal portion from the total thickness of the above-mentioned closure, i.e., the sealing thickness, may be 520 μm to 670 μm, preferably 525 μm or more, 530 μm or more, 535 μm or more, 1080 μm or more, and also 1160 μm or less, 1150 μm or less. The sealing thickness of the above-mentioned closure may have a thickness reduced by about 15% to 45% compared to the thickness before sealing, preferably 17% or more, 18% or more, or 20% or more, and also 43% or less, 41% or less, 40% or less, or 39% or less. When sealing is performed within this range, the pouch-type secondary battery can have the ability to maintain airtightness for a long period of time by securing the sealing thickness, and thus, improved durability can be expected.

[0158] The sealing thickness of the resin portion, excluding the thickness of the metal portion from the total thickness of the above-mentioned temporary sealing portion, may be 550 μm to 700 μm, preferably 560 μm or more, 570 μm or more, 575 μm or more, and may also be 690 μm or less, 680 μm or less, 670 μm or less, or 650 μm or less. The sealing thickness of the above-mentioned temporary sealing portion may have a thickness reduced by about 10% to 40% compared to the thickness before sealing, preferably 13% or more, 15% or more, or 16% or more, and may also be 38% or less, 36% or less, or 35% or less. By controlling the sealing thickness in this way through the control of the sealing process, it is possible to secure a low operating pressure while preventing problems of delamination between laminates other than the opening of the interface between the gas-inducing film and the lead film that induces opening.

[0159]

[0160] (4) Electrolyte

[0161] The pouch-type secondary battery (100) according to the present invention may further include an electrolyte (not shown) injected into the outer casing (110). The electrolyte is intended to move lithium ions generated by the electrochemical reaction of the electrodes during charging / discharging of the secondary battery (100), and may include a non-aqueous organic electrolyte, which is a mixture of a lithium salt and an organic solvent, or a polymer using a polymer electrolyte. Furthermore, the electrolyte may include a solid electrolyte of the sulfide type, oxide type, or polymer type, and such a solid electrolyte may have flexibility that allows it to be easily deformed by an external force.

[0162]

[0163] battery pack

[0164] In one aspect, the battery pack comprises a pouch-type secondary battery; and a packaging that accommodates the pouch-type secondary battery.

[0165] The above pouch-type secondary battery comprises: an electrode assembly; an outer material having a multilayer film structure including a metal layer, the outer material including a receiving portion for housing the electrode assembly and a sealing portion formed along the periphery so as to seal the receiving portion; and a lead assembly; wherein the lead assembly may include an electrode lead connected to the electrode assembly and protruding to the outside of the outer material via the sealing portion, an adhesive film disposed on the electrode lead, a gas induction film covering at least a portion of the adhesive film, comprising a permeable portion disposed in the direction of the outer material rather than the sealing portion and one or more gas flow paths disposed to extend from the permeable portion via the sealing portion toward the receiving portion, and a lead film disposed to be in contact with the outer material between the adhesive film and the outer material.

[0166] Additionally, the sealing portion may be characterized by having a partially closed portion in which the gas flow path is located and which can be opened or closed according to an increase in internal pressure, and a closed portion in which the gas induction film is not disposed, and having a step ratio (△T) defined by the following Equation 1 of 2.00% to 7.00%.

[0167] [Equation 1]

[0168] △T = [(T O - T C ) / T C ] x 100

[0169] In the above Equation 1, T O is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned temporary closure part, and T C is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned closure.

[0170] A detailed description of the above pouch-type secondary battery has been provided above, so it is omitted.

[0171] The above packaging may be provided as a box-shaped structure. The packaging may be made of metal or plastic having a predetermined rigidity. The packaging may have a structure in which a plurality of plates are combined.

[0172] However, the shape or structure of the packaging may be modified as needed. For example, at least a portion of the packaging may have a curved shape. Additionally, other components may be additionally provided in the packaging. For example, the packaging may be provided with a busbar electrically connected to a plurality of secondary batteries and / or a venting component communicating the inside and outside of the packaging.

[0173]

[0174] electrical device

[0175] An electric device according to one embodiment of the present invention may include the aforementioned pouch-type secondary battery, and, for example, the pouch-type secondary battery may be applied as a battery cell that is a power supply device, or as a battery module or battery pack in which a plurality of pouch-type secondary batteries are assembled.

[0176] The above electric device may include a portable device or a medium-to-large device, for example, the portable device may be a mobile phone, a laptop computer, or a digital camera, and the medium-to-large device may be one or more of a power tool; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0177]

[0178] The present invention will be explained in more detail below through specific embodiments. However, the following embodiments are merely examples to aid in understanding the invention and do not limit the scope of the invention. It is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of this description, and it is natural that such variations and modifications fall within the scope of the appended claims.

[0179]

[0180] Examples and Comparative Examples

[0181] Example 1

[0182] (1) Manufacturing of exterior materials

[0183] A pouch film laminate having a polyethylene terephthalate / nylon / aluminum alloy film / polypropylene film structure was manufactured by laminating a polyethylene terephthalate (PET) film with a width of 266 mm, a length of 50 m, and a thickness of 12 μm and a nylon film with a width of 266 mm, a length of 50 m, and a thickness of 25 μm on one side of an aluminum alloy film with a width of 266 mm, a length of 50 m, and a thickness of 80 μm on the other side, and laminating a polypropylene film with a width of 266 mm, a length of 50 m, and a thickness of 80 μm on the other side.

[0184] Here, the polyethylene terephthalate film and the nylon film are the substrate layer, the aluminum alloy thin film is the gas barrier layer, and the polypropylene film is the sealant layer.

[0185] An exterior material was manufactured comprising a receiving portion, a terrace portion, and a sealing portion formed by sealing a portion of the width of the terrace portion by molding the above pouch film laminate.

[0186]

[0187] (2) Manufacturing of pouch-type secondary batteries

[0188] An electrode assembly was manufactured by assembling a cathode, an anode, and a porous polyethylene separator using a stacking method and then laminating them. Subsequently, an electrode lead was attached to the electrode assembly.

[0189] An electrolyte was prepared by dissolving LiPF6 in a solvent (EC:EMC:DMC = 3:3:4 volume ratio) to a concentration of 1.0 M. The electrode assembly was housed in the outer casing with the tip of the electrode lead drawn out to the outside, and the electrolyte was injected.

[0190] A polytetrafluoroethylene tape (gas induction film) with a thickness of 50 μm in the shape of “TT” as shown in Fig. 3 was formed on an acid-modified polypropylene film (adhesive film) with a thickness of 43 μm on the upper surface of the electrode lead (aluminum, thickness 400 μm).

[0191] Next, a lead film with a thickness of 200 μm was laminated onto the lower surface of the electrode lead and the upper surface of the gas induction film, respectively. The lead film comprises a metal adhesive layer with a thickness of 75 μm comprising a polypropylene random copolymer and acid-modified polypropylene, a core layer with a thickness of 65 μm comprising a homopolymer polypropylene, and a pouch adhesive layer with a thickness of 60 μm comprising a copolymer polypropylene.

[0192] Subsequently, a pouch-type secondary battery was manufactured by sealing for 2 seconds at 220°C and 0.20 MPa using an upper sealing tool and a lower sealing tool, each having a seal bar area of ​​200 mm x 10 mm and steps formed in 1, 2, and 3 stages respectively according to the thickness to be sealed for the sealing portion of the outer material, the pouch film fusion portion, the fusion portion where the pouch film and lead film overlap, and the electrode lead fusion portion.

[0193]

[0194] Example 2

[0195] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that the third section of the upper sealing tool was raised by about 20 μm compared to Example 1 and sealed.

[0196]

[0197] Example 3

[0198] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that the third section of the upper sealing tool was raised by about 40 μm compared to Example 1 and sealed.

[0199]

[0200] Comparative Example 1

[0201] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that the third section of the upper sealing tool was lowered by about 30 μm compared to Example 1 and sealed.

[0202]

[0203] Comparative Example 2

[0204] A pouch-type secondary battery was manufactured in the same manner as in Example 1, except that the third section of the upper sealing tool was raised by about 60 μm compared to Example 1 and sealed.

[0205]

[0206] Closure (㎛, T C ) closed part (㎛, T O )△T Example 15 655863.72 Example 25 856083.93 Example 3 6076273.29 Comparative Example 15 325747.89 Comparative Example 26 236331.61

[0207]

[0208] Experimental Example 1: Measurement of operating pressure of a gas induction film

[0209] For the pouch-type secondary batteries prepared in Examples 1 to 3 and Comparative Examples 1 and 2, respectively, the internal pressure at which gas discharge begins was measured.

[0210] Specifically, CO2 was injected into the pouch-type secondary battery using ITS's pressure testing equipment, and the internal pressure of the pouch was increased in increments of 0.5 atm and left for 24 hours at each pressure level. The pressure at the point when the permeable portion of the gas induction film was completely deformed (when the interface between the lead film and the gas induction film in the permeable portion was completely open) was measured, and the results are shown in Table 1 below.

[0211]

[0212] Experimental Example 2: Measurement of Sealing Strength

[0213] For the pouch-type secondary batteries manufactured in Examples 1 to 3 and Comparative Examples 1 and 2, five specimens were extracted by cutting the sealing portion of each closed portion at 15 mm intervals. Then, the electrode lead was attached to the lower jig of the UTM and the outer material was attached to the upper jig. The sealing strength was measured by pulling in the 180° direction at a speed of 5 mm / min at room temperature and 60°C. The average value in the 8 mm section from the point exceeding 4.5 kgf / 15 mm was calculated to determine the low-speed sealing strength, and the average and maximum values ​​were obtained.

[0214]

[0215] Operating Pressure (atm) Top Surface Sealing Strength (kgf / 15mm) Bottom Surface Sealing Strength (kgf / 15mm) Room Temperature Average 60℃ Average Room Temperature Average 60℃ Average Example 1 1.6 9.8 79.6 69.8 0 9.27 Example 2 2.1 11.6 51 1.7 51 3.0 6 9.69 Example 3 2.3 13.2 21 2.9 41 1.2 71 0.46 Comparative Example 10.9 3.5 63.3 91 1.0 36.79 Comparative Example 2 2.5 12.5 75.9 31 2.5 77.63

[0216] Top surface sealing strength (kgf / 15mm) Bottom surface sealing strength (kgf / 15mm) Room temperature maximum value 60℃ maximum value Room temperature maximum value 60℃ maximum value Example 1 14.60 14.20 12.70 11.76 Example 2 15.11 14.56 16.97 12.18 Example 3 15.33 15.39 13.15 13.73 Comparative Example 18.32 8.10 12.57 8.74 Comparative Example 2 15.65 10.63 14.65 9.30

[0217] Referring to Tables 2 and 3 above, it can be confirmed that the secondary batteries of Examples 1 to 3 have superior performance in the lead assembly providing the gas discharge function compared to the secondary batteries of Comparative Examples 1 and 2. That is, in the case of Comparative Examples 1 and 2, which do not satisfy the step ratio, the sealing strength shows a significant variation between room temperature and high temperature, and it can be confirmed that problems with the sealing performance of the sealing part occur when the temperature of the battery rises slightly. However, in Examples 1 to 3, the sealing strength is the same at both room temperature and high temperature, and the operating pressure is not high, so it can be confirmed that the gas discharge function can be performed well without problems with the sealing performance of the sealing part.

[0218]

[0219] [Explanation of the symbol]

[0220] 100: Pouch-type secondary battery

[0221] 110: Exterior materials

[0222] 120: First case

[0223] 122: Cup

[0224] 124: Reception Department

[0225] 130: Case 2

[0226] 132: Cup

[0227] 140: Bridge section

[0228] 150: Terrace section

[0229] 151: Sealing part

[0230] 160: Electrode assembly

[0231] 170: Electrode tab

[0232] 172: Positive tab

[0233] 174: Cathode tab

[0234] 180: Electrode lead

[0235] 182: Positive lead

[0236] 184: Cathode Lead

[0237] 190: Lead film

[0238] 210: Adhesive film

[0239] 220: Gas induction film

[0240] 221: Transmissive part

[0241] 222: Gas Euro

[0242] 300: Gas exhaust path

Claims

1. Electrode assembly; an outer material having a multilayer film structure including a metal layer, comprising a receiving portion for housing the electrode assembly and a sealing portion formed along the periphery thereof so as to seal the receiving portion; and a lead assembly; The above lead assembly is, An electrode lead connected to the electrode assembly and protruding to the outside of the outer casing via the sealing portion, An adhesive film placed on the electrode lead, A gas induction film covering at least a portion of the adhesive film, comprising a permeable portion disposed in the direction of the outer surface of the exterior material rather than the sealing portion, and one or more gas flow paths disposed to extend from the permeable portion through the sealing portion toward the direction of the receiving portion, and It includes a lead film positioned to be in contact with the exterior material between the adhesive film and the exterior material, and The above sealing part is, A temporary closure section in which the above gas flow path is located and which can be opened or closed according to the increase in internal pressure, and It has a closed portion where the above gas induction film is not placed, and A pouch-type secondary battery having a step difference rate (△T) defined by the following Equation 1 of 2.00% to 7.00%: [Equation 1] △T = [(T O - T C ) / T C ] x 100 In the above Equation 1, T O is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned temporary closure part, and T C is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned closure.

2. In Paragraph 1, A pouch-type secondary battery having a step rate of 2.20% to 6.50%.

3. In Paragraph 1, The above pouch-type secondary battery is a pouch-type secondary battery in which, when the internal pressure of the outer material increases, the interface between the lead film and the gas induction film at the closed portion is opened.

4. In Paragraph 1, In the above pouch-type secondary battery, when the internal pressure of the outer material increases, the interface between the gas induction film and the lead film at the closed portion opens, allowing gas to move to the permeable portion. A pouch-type secondary battery in which gas is discharged through a lead film on the above-mentioned transparent portion.

5. In Paragraph 1, The total thickness (T) of the above-mentioned closure part S A pouch-type secondary battery having a diameter of 1060 μm to 1170 μm.

6. In Paragraph 1, The lead assembly of the above-mentioned temporary closure portion comprises a lower outer casing, a lower lead film, an electrode lead, a gas induction film, an upper lead film, and an upper outer casing, forming a pouch-type secondary battery.

7. In Paragraph 1, The lead assembly of the above-mentioned closure comprises a lower outer casing, a lower lead film, an electrode lead, an upper lead film, and an upper outer casing, forming a pouch-type secondary battery.

8. In Paragraph 1, The above adhesive film is a pouch-type secondary battery in which one end protruding outwardly from the exterior material protrudes further than one end of the gas induction film protruding outwardly from the exterior material.

9. In Paragraph 1, The above lead film is a pouch-type secondary battery in which one end protruding outwardly from the outer casing protrudes further than one end of the permeable resin layer protruding outwardly from the outer casing.

10. Pouch-type secondary battery; and It includes a packaging that accommodates the above pouch-type secondary battery, and The above pouch-type secondary battery is, An electrode assembly; an outer material having a multilayer film structure including a metal layer, comprising a receiving portion for housing the electrode assembly and a sealing portion formed along the periphery so as to seal the receiving portion; and a lead assembly; The above lead assembly is, An electrode lead connected to the electrode assembly and protruding to the outside of the outer casing via the sealing portion, An adhesive film placed on the electrode lead, A gas induction film covering at least a portion of the adhesive film, comprising a permeable portion disposed in the direction of the outer surface of the exterior material rather than the sealing portion, and one or more gas flow paths disposed to extend from the permeable portion through the sealing portion toward the direction of the receiving portion, and It includes a lead film positioned to be in contact with the exterior material between the adhesive film and the exterior material, and The above sealing part is, A temporary closure section in which the above gas flow path is located and which can be opened or closed according to the increase in internal pressure, and It has a closed portion where the above gas induction film is not placed, and A battery pack having a step difference ratio (△T) defined by the following Equation 1 of 2.00% to 7.00%: [Equation 1] △T = [(T O - T C ) / T C ] x 100 In the above Equation 1, T O is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned temporary closure part, and T C is the thickness obtained by subtracting the thickness of the metal layer of the electrode lead and the outer material from the total thickness of the lead assembly of the above-mentioned closure.

11. An electric device comprising a battery pack as described in paragraph 10.

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