Pouch type battery cartridge and lithium secondary battery

Abstract

The pouch-type battery cartridge according to the present invention comprises: a cup-shaped portion having an accommodation space in which an electrode assembly is accommodated; a platform portion formed along a periphery of the accommodation space; and a gas discharge portion, in which the gas discharge portion includes at least one through hole formed in the cup-shaped portion or the platform portion and a gas-permeable membrane covering the through hole, the gas-permeable membrane is sealed in the battery case so as to form a sealed area around the through hole, and the gas discharge portion has an anti-deflation index (AVI) less than or equal to 3.0. According to the present invention, in a case where a gas discharge portion satisfying a deflation prevention index is satisfied, gas is smoothly discharged due to a relatively low operating pressure, and durability is excellent due to a high complete deflation pressure, and thus it is possible to provide a pouch-type secondary battery having improved safety and service life.

Description

Technical Field

[0001] The present invention relates to a pouch-type battery case and a pouch-type secondary battery including the pouch-type battery case, and more specifically, to a pouch-type battery case including a gas emission portion exhibiting excellent durability and efficient gas emission performance and a pouch-type secondary battery including the pouch-type battery case. Background Technology

[0002] Rechargeable batteries are used in a wide range of products, including small products such as digital cameras, P-DVD players, MP3 players, mobile phones, PDAs, portable gaming devices, power tools, and electric bicycles, as well as large products requiring high power, such as electric vehicles and hybrid vehicles. They are also used in power storage devices for storing surplus or renewable energy, and in backup power storage devices. Rechargeable batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries.

[0003] Secondary batteries are manufactured by housing an electrode assembly in which positive, negative, and spacers sandwiched between electrodes are alternately stacked in a battery case, injecting electrolyte, and then sealing the battery case. Depending on the material of the case housing the electrode assembly, secondary batteries are classified into pouch-type and can-type secondary batteries. Specifically, pouch-type batteries are manufactured by pressing a stretchable pouch film laminate to form a cup-shaped portion, then housing the electrode assembly within the containment space of the cup-shaped portion and sealing the portion.

[0004] When operated at high temperatures, overcharged, or short-circuited, pouch-type secondary batteries may generate gas inside the pouch. As the gas pressure inside the pouch increases, the pouch may leak, potentially leading to an explosion or fire. To overcome these limitations, a component designed to continuously release gas without stopping battery operation is required.

[0005] Although extensive research is underway to incorporate valve-type gas venting components for discharging gases generated inside batteries, most valve-type gas venting components are made of heavy materials and require high operating pressures, thus often failing to address the expansion caused by gas generation.

[0006] Therefore, efforts are underway to develop gas emission components that allow only gas to pass through by modifying the lead film in the electrode lead section or by punching a hole in a part of the battery box and sealing the hole with a breathable membrane, while preventing the migration of moisture and electrolyte.

[0007] However, in the case of membranes that only allow gas to pass through, as described above, depending on the materials used, the possibility of liquid infiltration increases when the permeability is high, as well as concerns about poor adhesion of the battery box. When the risk of liquid infiltration is reduced to zero, the desired level of gas emission performance cannot be achieved.

[0008] In addition, the dimensional characteristics of the components that make up the gas emission component cause changes in gas emission performance, pressure at the start of operation, and pressure when leakage occurs. Since the specific dimensions that may affect gas emission performance have not yet been clearly identified, further research is needed to develop gas emission components that exhibit excellent performance. Summary of the Invention

[0009] Technical issues

[0010] The present invention is designed to overcome the above-mentioned limitations, and therefore, one aspect of the present invention provides a pouch-type battery case that limits the venting index by utilizing a through-hole communicating with the interior and exterior of the case and a precisely designed breathable membrane covering the through-hole, promotes gas discharge and exhibits excellent durability under high internal pressure, the through-hole and the breathable membrane forming the gas discharge portion.

[0011] Furthermore, the present invention is designed to overcome the above-mentioned limitations, and therefore, another aspect of the present invention provides a pouch-type secondary battery exhibiting excellent safety and extended service life by applying the above-described pouch-type battery case.

[0012] Technical solution

[0013] [1] According to one aspect of the present invention, a pouch-type battery box is provided, the pouch-type battery box comprising: a cup-shaped portion having a receiving space for receiving an electrode assembly; a platform portion formed along the periphery of the receiving portion; and a gas venting portion, wherein the gas venting portion is disposed at at least one of the cup-shaped portion and the platform portion, each gas venting portion comprising at least one through hole and a breathable membrane covering the through hole, the breathable membrane being sealed to the battery box to form a sealed area around the through hole, and the gas venting portion having a leak-proof index (AVI) of less than or equal to 3.0 as defined by Equation 1 below.

[0014] [Equation 1]

[0015] AVI = [A h xr h ] / [W s x C h ]

[0016] In equation 1 above, A h It is the total cross-sectional area (mm²) of the through hole given as a unitless number. 2 ), r h W is the average radius (mm) of the through hole given as a unitless number. s It is the average width (mm) of the sealed area given as a unitless number, and C h It is the total circumference (mm) of the through hole given as a unitless number.

[0017] [2] The present invention provides a pouch-type battery box according to [1] above, wherein the air leakage index (AVI) can be in the range of 0.10 to 2.50.

[0018] [3] The present invention provides a pouch-type battery box according to [1] or [2] above, wherein the ratio of the average width of the sealing area of ​​the gas venting portion to the average radius of the through hole can be from 0.45 to 3.00.

[0019] [4] The present invention provides a pouch-type battery box according to at least one of [1] to [3] above, wherein the ratio of the total cross-sectional area of ​​the through hole of the gas emission portion to the total perimeter of the through hole can be from 0.25 mm to 2.50 mm.

[0020] [5] The present invention provides a pouch-type battery box according to at least one of [1] to [4] above, wherein a gas venting portion may be formed at at least one location selected from a platform portion and a cup-shaped portion located adjacent to the platform portion and having no internal contact with the electrode assembly.

[0021] [6] The present invention provides a pouch-type battery box according to at least one of [1] to [5] above, wherein the number of through holes may be in the range of 1 to 6.

[0022] [7] The present invention provides a pouch-type battery case according to at least one of [1] to [6] above, wherein the through hole may have 5 mm 2 Up to 25 mm 2 Total cross-sectional area (A) H ).

[0023] [8] The present invention provides a pouch-type battery case according to at least one of [1] to [7] above, wherein the breathable membrane may have a thickness of 80 μm to 500 μm.

[0024] [9] The present invention provides a pouch-type battery box according to at least one of [1] to [8] above, wherein a breathable membrane may be disposed inside the battery box.

[0025]

[10] The present invention provides a pouch-type battery case according to at least one of [1] to [9] above, wherein the breathable membrane may include an adhesive resin layer in contact with the battery case and a breathable resin layer disposed on the adhesive resin layer.

[0026]

[11] The present invention provides a pouch-type battery box according to

[10] above, wherein the adhesive resin layer may comprise a non-fluorinated polyolefin-based resin.

[0027]

[12] The present invention provides a pouch-type battery case according to at least one of

[10] and / or

[11] above, wherein the breathable resin layer may comprise a fluorinated polyolefin-based resin.

[0028]

[13] The present invention provides a pouch-type battery case according to at least one of

[10] to

[12] above, wherein the thickness (T) of the adhesive resin layer is […]. A ) and the thickness of the breathable resin layer (T) T The ratio of (T) A / T T It can be in the range of 0.4 to 2.0.

[0029]

[14] The present invention provides a pouch-type battery box according to at least one of [1] to

[13] above, wherein the pouch-type battery box may have a structure in which a base layer, a gas barrier layer and a sealant layer are stacked sequentially from the outside.

[0030]

[15] According to another aspect of the invention, a pouch-type secondary battery is provided, the pouch-type secondary battery comprising: an electrode assembly; the aforementioned pouch-type battery case; an electrode lead connected to the electrode assembly and protruding to the outside of the pouch-type battery case via a platform portion; and a lead film disposed on the platform portion between the electrode lead and the pouch-type battery case, wherein a portion of the platform portion is sealed along the periphery of the cup-shaped portion to form a sealing portion.

[0031] Beneficial effects

[0032] The pouch-type battery box according to the invention can be implemented as a pouch-type battery box with a gas venting section. The pouch-type battery box limits the gas leakage index by utilizing the design dimensions of the through-hole forming the gas venting section communicating with the inside and outside of the box and the breathable membrane covering the through-hole, promoting gas venting and exhibiting excellent durability under high internal pressure.

[0033] In addition, the pouch-type secondary battery according to the present invention exhibits excellent safety and enhanced durability, and the application of the above-described pouch-type battery case helps to improve service life. Attached Figure Description

[0034] The accompanying drawings, which illustrate preferred embodiments of the invention by way of example, are used together with the detailed description of the invention given below to enable a further understanding of the technical concept of the invention, and therefore should not be construed as being limited to the contents of these drawings.

[0035] Figure 1 This is an exploded view of a pouch-type secondary battery;

[0036] Figure 2 This is a plan view of a pouch-type secondary battery;

[0037] Figure 3 This is a cross-sectional view of the portion of a pouch-type secondary battery that has a gas emission section.

[0038] Figure 4 This is an enlarged cross-sectional view of the portion of a pouch-type secondary battery that has a gas emission section.

[0039] Figure 5 It is a plan view of a pouch-type secondary battery with multiple gas emission sections;

[0040] Figure 6 yes Figure 5 Enlarged plan view of the pouch-type secondary battery in region A;

[0041] Figure 7 yes Figure 5 An enlarged plan view of a portion of a pouch-type secondary battery in region A; and

[0042] Figure 8 yes Figure 5 An enlarged plan view of a portion of a pouch-type secondary battery in region A. Detailed Implementation

[0043] The advantages and features of this disclosure, as well as methods for achieving these advantages and features, can be more readily understood from the following detailed description with reference to the embodiments and accompanying drawings. However, this disclosure may be implemented in different forms, and these embodiments are provided only to make the disclosure thorough and complete and to fully convey the scope of the disclosure to those skilled in the art, and therefore the disclosure is limited only by the scope of the appended claims. Throughout the specification, the same reference numerals denote the same elements.

[0044] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Unless explicitly and specifically defined, terms as defined in commonly used dictionaries shall not be interpreted ideally or excessively.

[0045] The terminology used herein is not intended to limit the invention, but rather to describe embodiments. As used herein, singular terms are intended to include plural forms as well, unless the context clearly indicates otherwise. The meaning of “comprising” and / or “including” as used herein does not exclude the presence or addition of one or more other components besides those mentioned.

[0046] As used herein, when an element “includes” a component, it may indicate that the element does not exclude another component, but may also include another component, unless there is an explicit description to the contrary.

[0047] As used in this article, the description “A and / or B” means either A or B or A and B.

[0048] As used herein, unless otherwise indicated, “%” indicates wt%.

[0049] The pouch-type battery box and pouch-type secondary battery described herein may include at least one of the technical components described later, and may include any combination of technically feasible components from the following technical components.

[0050] pouch battery box

[0051] Implementation Method 1

[0052] According to embodiment 1, the pouch-type battery box includes a cup-shaped portion having a receiving space for accommodating electrode assemblies, a platform portion along the periphery of the receiving portion, and a gas venting portion, wherein the gas venting portion is disposed in at least one of the cup-shaped portion or the platform portion, each gas venting portion including at least one through hole and a breathable membrane covering the through hole, the breathable membrane being sealed to the battery box to form a sealed area around the through hole, and the gas venting portion having a leak-proof index (AVI) of less than or equal to 3.0, as defined by Equation 1 below.

[0053] [Equation 1]

[0054] AVI = [A h xr h ] / [W s x C h ]

[0055] In equation 1 above, A h It is the total cross-sectional area (mm²) of the through hole given as a unitless number. 2 ), r h W is the average radius (mm) of the through hole given as a unitless number. s It is the average width (mm) of the sealed area given as a unitless number, and C h It is the total circumference (mm) of the through hole given as a unitless number.

[0056] Generally, the gas emission performance of a gas emission section is determined by the properties of the materials that constitute the gas emission section. The properties of the materials determine the water permeability and electrolyte leakage resistance, and gas permeability also varies depending on the material. Therefore, the materials constituting the gas emission section are a decisive factor.

[0057] However, while materials are important, it is clear that there are areas not defined by materials and factors that can improve gas emission performance independently of materials, and therefore Implementation 1 aims to introduce a gas emission section that exhibits high internal pressure resistance and excellent emission performance by defining a leak-proof index for gas emission through a through-hole formed in the pouch-type battery box.

[0058] Specifically, when gas is discharged through the orifices in the gas discharge section, the number of orifices formed and the increase in the total cross-sectional area of ​​the orifices affect the efficiency of gas discharge, but the ability to resist increased internal pressure varies depending on the total perimeter of the orifices. Furthermore, a smaller average radius of the orifices leads to greater stress from the internal gas, making it more difficult to withstand high internal pressure. However, multiple smaller orifices with equal total cross-sectional areas can enhance resistance to internal pressure. In addition, increasing the width of the sealing area can further enhance resistance to high internal pressure.

[0059] Therefore, achieving a gas discharge section that can withstand high internal pressure, discharge gas from the beginning of generation, and even exhibit excellent discharge performance requires the interaction of quite complex factors, and the setting of a single through hole or multiple through holes is also affected by the specific dimensions involved, and thus these different factors can be taken into account to define the leak-proof index.

[0060] Figure 1 This is an exploded view of the pouch-type secondary battery 100. Figure 2 This is a plan view of a pouch-type secondary battery 100. Figure 3 This is a cross-sectional view of the portion of the pouch-type secondary battery housing where a gas emission section is located. Figure 4 This is an enlarged cross-sectional view of the portion of the pouch-type secondary battery housing where a gas venting section is located. Figure 2 For ease of understanding, some components of the pouch-type secondary battery 100 are omitted. For example... Figures 1 to 4 As shown, the pouch-type secondary battery 100 of the present invention includes a pouch-type battery case 110 containing a gas emission section 200, an electrode assembly 160, an electrode lead 180, and a lead film 190 according to the present invention.

[0061] In the following text, refer to Figures 1 to 4 The present invention will be described in detail in the form of a pouch-type battery box 110 and a pouch-type secondary battery 100.

[0062] In one aspect, the pouch-type battery box 110 includes cup-shaped portions 122 and 132, a platform portion 150, and a gas emission portion 200. The cup-shaped portions 122 and 132 have receiving spaces in which electrode assemblies 160 are accommodated. The platform portion 150 is formed along the periphery of the cup-shaped portions 122 and 132. The gas emission portion 200 has at least one through-hole 220 and a breathable membrane 210 for closing the through-hole.

[0063] Battery box

[0064] The pouch-type battery case 110 can accommodate the electrode assembly 160 within its internal receiving space. The pouch-type battery case 110 can be manufactured by molding a pouch film laminate. In this case, as... Figure 4 As shown, the pouch-type battery box may include a base layer 111, a gas barrier layer 112, and a sealant layer 113. The base layer 111, the gas barrier layer 112, and the sealant layer 113 may be stacked sequentially.

[0065] A base layer 111 is formed on the outermost layer of the bag film laminate to protect the secondary battery from external friction and impact. The base layer is made of polymer, and thus provides electrical insulation between the electrode assembly and the external environment.

[0066] The base layer 111 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-phenylenebenzodioxazole), polyarylate, Teflon, and glass fiber. Preferably, the base layer may be made of polyethylene terephthalate (PET), nylon, or combinations thereof, which have abrasion resistance and heat resistance.

[0067] The base layer 111 can have a single-film structure made of any material. Alternatively, the base layer 111 can have a composite film structure formed of two or more materials, each forming a layer.

[0068] The base layer 111 can have a thickness of 5 μm to 50 μm, specifically 7 μm to 40 μm, and more specifically 25 μm to 38 μm. When the thickness of the base layer meets the above range, the external insulation properties are excellent and the entire bag is not thick, and therefore, the energy density of the secondary battery relative to its volume can be excellent.

[0069] A gas barrier layer 112 is stacked between the base layer 111 and the sealant layer 113 to ensure the mechanical strength of the bag, block the entry and exit of external gases or moisture from the secondary battery, and prevent electrolyte leakage from the inside of the bag-type battery box.

[0070] The gas barrier layer 112 can be formed of a metal, and specifically of an aluminum alloy film. When the gas barrier layer 112 is formed using an aluminum alloy film, the gas barrier layer can have a predetermined level of mechanical strength and is also lightweight, and can supplement the electrochemical properties caused by the electrode assembly and electrolyte and achieve heat dissipation. The aluminum alloy film may include metallic elements other than aluminum (Al), for example, it may include 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).

[0071] The gas barrier layer 112 can have a thickness of 40 μm to 100 μm, specifically 50 μm to 90 μm, and more specifically 55 μm to 85 μm. When the thickness of the gas barrier layer 112 meets the above ranges, the moldability and gas barrier performance are excellent when molding the cup-shaped portion.

[0072] The sealant layer 113 is thermally bonded together at the sealing portion when the pouch battery case, which houses the electrode assembly, is sealed to completely seal the interior of the pouch battery case. For this purpose, the sealant layer 113 can be formed of a material with excellent thermal bonding strength.

[0073] The sealant layer 113 can be formed of a material having insulating, corrosion-resistant, and sealing properties. Specifically, the sealant layer 113 is in direct contact with the electrode components and / or electrolyte inside the pouch cell, and therefore can be formed of a material having insulating and corrosion-resistant properties. Furthermore, the sealant layer 113 should completely seal the interior of the pouch cell and prevent material movement between the interior and exterior, and therefore can be formed of a material with high sealing properties (e.g., excellent thermal bonding strength). To ensure such insulating, corrosion-resistant, and sealing properties, the sealant layer 113 can be formed of a polymer material.

[0074] The sealant layer 113 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-phenylenebenzodioxazole), 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, polypropylene may include cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butene-ethylene terpolymer.

[0075] The sealant layer 113 may have a thickness of 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 113 meets the above ranges, it has the effect of ensuring both the sealing strength of the sealed portion and the moldability of the bag film laminate.

[0076] The pouch-type battery case 110 can be manufactured by drawing, molding, or stretching using a punch or similar means. Therefore, the pouch-type battery case 110 may include a cup-shaped portion 122 and a receiving portion 124. The receiving portion 124 is a place for receiving electrode assemblies and may indicate a receiving space formed in the shape of a pouch within the cup-shaped portion 122 when the cup-shaped portion 122 is formed.

[0077] According to an embodiment of the present invention, the pouch-type battery box 110 may include a first box 120 and a second box 130, such as Figure 1 As shown in the diagram, the first box 120 may include a receiving portion 124 capable of accommodating the electrode assembly 160, and the second box 130 may cover the receiving portion 124 from above to prevent the electrode assembly 160 from separating to the outside of the battery box 110. The first box 120 and the second box 130 may be as follows: Figure 1 The manufacturing shown allows one side of the first box 120 and one side of the second box 130 to be connected to each other, but embodiments of the invention are not limited thereto, and the first box 120 and the second box 130 may be manufactured differently, for example, by being manufactured separately from each other.

[0078] When forming cup-shaped portions in a bag film laminate, two symmetrical cup-shaped portions 122 and 132 adjacent to each other can be drawn and molded in one bag film laminate. In this case, cup-shaped portions 122 and 132 can be formed in the first box 120 and the second box 130, respectively, as shown. Figure 1 As shown, after the electrode assembly 160 is housed in the receiving portion 124 within the cup-shaped portion 122 of the first housing 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 housing 130 can accommodate the electrode assembly 160 from above. Therefore, the two cup-shaped portions 122 and 132 accommodate one electrode assembly 160, and thus can accommodate a thicker electrode assembly 160 than when only one cup-shaped portion 122 is present. In addition, one edge of the secondary battery 100 is formed by folding the pouch-type battery case 110, and therefore, the number of edges to be sealed can be reduced when a 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.

[0079] like Figure 2 As described, the pouch-type battery case 110 can be sealed while housing the electrode assembly 160, exposing a portion of the electrode leads 180, i.e., the terminal portion, which will be described later. Specifically, when the electrode leads 180 are connected to the electrode tabs 170 of the electrode assembly 160 and a lead film 190 is formed on a portion of the electrode leads 180, the electrode assembly 160 can be housed in a receiving portion 124 disposed in the cup-shaped portion 122 of the first case 120, and the second case 130 can cover the receiving portion 124 from above. Then, as described above, electrolyte is injected into the receiving portion 124, and a portion of the platform portion 150 formed along the periphery of the first case 120 and the second case 130 can be sealed to form a sealing portion 151.

[0080] The sealing portion 151 can be used to seal the receiving portion 124. Specifically, the sealing portion can seal the receiving portion 124 by forming a platform portion 150 along the periphery of the receiving portion 124.

[0081] The sealing temperature of the sealing portion 151 can be from 180°C to 250°C, specifically from 200°C to 250°C, and more specifically from 211°C to 240°C. When the sealing temperature meets the numerical range described above, the pouch-type battery box 110 can achieve sufficient sealing strength through thermal bonding.

[0082] Gas emission section

[0083] According to embodiment 1, the pouch-type battery box 110 includes at least one through hole 220 formed in a cup-shaped portion or a platform portion and a breathable membrane 210 covering the through hole 220, wherein the air leakage index (AVI) defined by Equation 1 below is less than or equal to 3.0, and the breathable membrane 210 is sealed to the battery box 110 to form a sealed area 230 around the through hole 220.

[0084] [Equation 1]

[0085] AVI = [A h xr h ] / [W s x C h ]

[0086] In equation 1 above, A h It is the total cross-sectional area (mm²) of the through hole given as a unitless number. 2 ), r h W is the average radius (mm) of the through hole given as a unitless number. s It is the average width (mm) of the sealed area given as a unitless number, and C hIt is the total circumference (mm) of the through hole given as a unitless number.

[0087] As described above, the leak-proof index (AVI) is defined based on the design dimensions of the through-hole 220 and the breathable membrane 210 constituting the gas emission section 200.

[0088] Importantly, the gas exhaust section 200 operates at low operating pressures and exhibits excellent gas exhaust performance; however, even more importantly, the gas exhaust section 200 is durable enough to withstand high internal pressures without leaking. To increase the ultimate internal pressure that can be withstood without leaking, the cross-sectional area (A) of the gas permeation through-hole 220 in the gas exhaust section 200 is... h The pouch-type battery compartment 110 could be designed to be larger to reduce the tension exerted by the internal gas; however, in this case, the area in which the through-hole 220 can be provided in the pouch-type battery compartment 110 is limited, and its maximum size is also limited. Furthermore, the possibility of moisture infiltration or electrolyte leakage from the outside cannot be ignored.

[0089] However, when the total cross-sectional area (A) of the through hole 220 is... h At an appropriate level, the number of through holes 220 and the average radius (r) of through holes 220 are determined. h Control is used to form a shape with an appropriate width (W) s When the sealing area 230 of the through-hole 220 is within the sealed region, the gas discharge section 200 exhibits excellent durability under high internal pressure under optimal conditions. That is, within the total cross-sectional area (A) of the through-hole 220... h Under the same conditions, when the number of through holes 220 is increased to increase the total perimeter (C) h When the average radius (r) of the through hole 220 is... h As the pressure decreases, the tension exerted by the internal gas also disperses, thereby increasing the ultimate internal pressure. Additionally, when the average width (W) of the sealing region 230... s As the diameter of the through-hole increases, the limiting internal pressure can increase further. However, even with the total circumference of the 220-degree bore (C), the internal pressure can still be increased. h When the radius (r) of the through hole 220 increases, h ) increases and the total cross-sectional area (A) h When both increase together, the ultimate internal pressure even reaches the average width (W) of the sealed area. s When it increases, it decreases instead.

[0090] With the average width (W) of the sealing area 230 s As the internal pressure increases, the expected ultimate internal pressure also increases; however, this relationship is not simple and independent, and it can be seen that the effect on durability under ultimate internal pressure varies depending on the average radius (r) of the through-hole 220. h) and the total cross-sectional area of ​​the through hole 220 (A) h ) and total perimeter (C h )change.

[0091] Considering these characteristics and relationships, the total cross-sectional area of ​​the through hole 220 (A) is calculated. h ) and total perimeter (C h The ratio of (A) h / C h ) and the average width of the sealing area (W) s ) and the average radius (r) of the through hole 220 h The ratio of (W) s / r h The leak-proof index is defined as the gas emission portion that exhibits excellent ability to withstand extreme internal pressure when the leak-proof index is smaller.

[0092] In one aspect, the venting resistance index is less than or equal to 3.0, and specifically, it can be greater than or equal to 0.10, greater than or equal to 0.15, greater than or equal to 0.20, greater than or equal to 0.25, or greater than or equal to 0.30, and can also be less than or equal to 2.80, less than or equal to 2.60, less than or equal to 2.50, less than or equal to 2.40, or less than or equal to 2.30. When the venting resistance index is less than 0.10, the venting pressure may be high, but poor gas venting may cause expansion or venting into the sealing portion of the pouch-type battery box 110. In addition, when the venting resistance index is greater than 3.0, the venting pressure is low and cannot meet the limit internal pressure that can ensure battery safety, and from this point of view, moisture penetration and electrolyte leakage become problems. Therefore, in the pouch-type battery box 110 according to an embodiment of the present invention, it is preferable to design the gas venting portion 210 to meet the above-mentioned range of venting resistance index.

[0093] The total cross-sectional area of ​​the through hole 220 (A) h ) and total perimeter (C h The sum of the cross-sectional area and perimeter of the formed through-hole 220 can be represented by the average radius (r) of the through-hole 220. h The average radius of the formed through-hole 220 and the average width (W) of the sealing area 230 can be represented. h The value can represent the average width of the sealing region 230 formed around each through hole 220. Typically, the width of the sealing region 230 formed around a through hole 220 is uniform, but when the widths are inconsistent, the average value can be used as described above.

[0094] In one aspect, the relationship between some factors that define the leak-proof index of the gas emission section 200 can also be defined, and for example, the average width (W) of the sealing area 230.s ) and the average radius (r) of the through hole 220 h The ratio of (W) s / r h The ratio (W) can range from 0.45 to 3.00. Specifically, the ratio (W) s / r h The value can be greater than or equal to 0.50, greater than or equal to 0.55, greater than or equal to 0.60, or greater than or equal to 0.65, and can be less than or equal to 2.80, less than or equal to 2.70, less than or equal to 2.60, less than or equal to 2.50, or less than or equal to 2.40. When the total cross-sectional area of ​​the through hole 220 is the same and the above ratios are satisfied, the ultimate internal pressure can be increased.

[0095] As another example, the total cross-sectional area (A) of the through hole 220 h ) and total perimeter (C h The ratio of (A) h / C h The ratio (A) can be in the range of 0.25 mm to 2.50 mm. Preferably, the ratio (A) h / C h The through hole 220 can be greater than or equal to 0.30 mm, greater than or equal to 0.40 mm, greater than or equal to 0.50 mm, greater than or equal to 0.60 mm, greater than or equal to 0.70 mm, or greater than or equal to 0.75 mm, and can also be less than or equal to 2.40 mm, less than or equal to 2.20 mm, less than or equal to 2.00 mm, less than or equal to 1.80 mm, less than or equal to 1.50 mm, or less than or equal to 1.25 mm. In this case, it can be said that the through hole 220 is set in the limited space in which the through hole 220 can be set with optimal efficiency, because the basic condition of increasing the limit of internal pressure is met.

[0096] Area of ​​the through hole (A) H It can be 5 mm 2 Up to 25 mm 2 Preferably 6 mm 2 Up to 23 mm 2 And more preferably 7 mm 2 Up to 20 mm 2 Within the range described above, the design of the permeability index may become easier relative to the thickness of the permeable membrane 210, and the gas emission section 200 can exhibit excellent gas emission performance while maintaining durability under reduced operating pressure.

[0097] In the following text, reference will be made to Figures 2 to 4 The gas emission section 200 is described in more detail. Figure 2This is a plan view of an example pouch-type secondary battery showing the location where the gas emission section 200 is formed. Figure 3 It is a cross-sectional view of the pouch-type secondary battery at the portion forming the gas emission section 200, and Figure 4 yes Figure 3 Enlarged cross-sectional view of the gas emission section 200.

[0098] The gas emission portion 200 may be formed at at least one location selected from the platform portion 150 and the cup-shaped portions 122 and 132 located adjacent to the platform portion 150 and having no internal contact with the electrode assembly. In this case, the cup-shaped portions 122 and 132 and the receiving portion 124 may be substantially indistinguishable in structure, and the recessed portions formed by molding in the pouch-type battery case 110 may be named the cup-shaped portions 122 and 132, and the receiving space formed by these recesses may be named the receiving portion 124.

[0099] Reference Figure 2 and Figure 3 The gas emission portion 200 can be formed in the platform portion 150, and can also be formed in the cup-shaped portion 122 or the receiving portion 124 adjacent to the platform portion 150. In particular, the electrode assembly 160 is received and sealed inside the pouch battery case 110 to form a sealing portion 151, and preferably, the sealing portion 151 can be formed in a portion of the cup-shaped portion 122 that is adjacent to the platform portion 150 and located inside the pouch battery case 110 without direct contact with the electrode assembly 160, i.e., the space where the electrode tab 170 is extracted from the electrode assembly 160 to make electrical connection with the outside and contact the electrode lead 180.

[0100] The gas emission section 200 can be formed as a single unit, or it can be configured as two or more units. The number of gas emission sections 200 can be designed with consideration of the characteristics of the battery for internal applications, such as whether the amount of gas produced is large or small. There is no particular limitation on the number as long as each gas emission section 200 is designed to meet the gas leakage prevention index. However, it is preferable that one to six units can be formed, and more preferably, one to five units can be formed.

[0101] like Figure 3As shown, in the gas emission section 200, a breathable membrane 210 can be provided inside the pouch-type battery box 110. In this case, the portion of the breathable membrane 210 in contact with the pouch-type battery box 110 can be sealed by means such as heat fusion, or it can be sealed using an adhesive. However, a heat-fusion seal is preferred in terms of durability, and even more preferred in terms of preventing electrolyte leakage and blocking moisture penetration, and can help to accurately reflect the performance that can be achieved by the gas permeability index.

[0102] Reference Figure 4 It can be seen under magnification. Figure 3 The gas emission section 200 shown, and the adhesive resin layer 211 of the breathable membrane 210, can be configured to contact the sealant layer 113 of the pouch-type battery case 110. In this case, the sealing effect through heat fusion can be maximized, which can help improve durability.

[0103] According to embodiments of the present invention, such as Figure 4 As shown, the gas emission section 200 may include an adhesive resin layer 211 in contact with the pouch-type battery box 110 and a breathable resin layer 212 disposed on the adhesive resin layer 211.

[0104] The adhesive resin layer 211 contacts the pouch-type battery case 110 and is intended to bond the gas emission portion 200 to the pouch-type battery case 110, and may include any material that facilitates bonding to the pouch-type battery case 110. Specifically, the adhesive resin layer 211 may comprise a non-fluorinated polyolefin-based resin, and preferably may comprise a modified polyolefin resin.

[0105] When the adhesive resin layer 211 includes a modified polyolefin resin, the adhesive strength between the gas venting portion 200 and the pouch battery case 110 is improved, and therefore, even when the pouch secondary battery is stored in a high-temperature environment, the gas venting portion 200 can be prevented from detaching from the electrode leads 180, thereby preventing electrolyte leakage and moisture penetration inside the pouch.

[0106] The adhesive resin layer 211 may include at least one of an acid-modified polyolefin or a silane-modified polyolefin.

[0107] Acid-modified polyolefins refer to polyolefin resins that have been grafted with acid. For example, acid-modified polyolefins can be obtained by reacting an unsaturated carboxylic acid with a polyolefin resin to introduce carboxyl groups (grafting modification). 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 undergoing reaction with the polyolefin resin can include, but is not limited to, at least one selected from maleic acid, fumaric acid, itaconic acid, citraconic acid, pentadienoic acid, tetrahydrophthalic acid, aconitic acid, maleic anhydride, itaconic anhydride, pentadienoic anhydride, citraconic anhydride, aconitic anhydride, norbornene dicarboxylic anhydride, and tetrahydrophthalic anhydride. In particular, maleic anhydride is preferred to improve the adhesion between the gas emission section 200 and the electrode lead 180. Acid-modified polyolefins can include, but are not limited to, at least one selected from acid-modified polypropylene (PPa) and acid-modified polyethylene (PEa).

[0108] Silane-modified polyolefins refer to polyolefin resins grafted with unsaturated silane compounds. Silane-modified polyolefins may have a structure in which the unsaturated silane compound is graft copolymerized with a polyolefin resin as the main chain. Silane-modified polyolefin resins may include, but are not limited to, at least one selected from silane-modified polypropylene resins and silane-modified ethylene-vinyl acetate copolymers.

[0109] The adhesive resin layer 211 can be modified, and examples of modification treatments include ion implantation, plasma treatment, irradiation treatment, heat treatment, etc., and preferably treatments that change the bonding structure of the polymer layer. These modification treatments can be performed alone or in combination of two or more types. The modified adhesive resin layer 211 may include, but is not limited to, plasma-treated polypropylene (PP).

[0110] The adhesive resin layer 211 can have a thickness of 20 μm to 250 μm, specifically 30 μm to 200 μm, and more specifically 30 μm to 150 μm. When the thickness of the adhesive resin layer 211 meets the above numerical range, the adhesive resin layer 211 melts within a specified cycle time, and accordingly, the gas emission portion 200 and the pouch-type battery box 110 can be easily fused together.

[0111] In one aspect, the breathable resin layer 212 may be a layer that contacts the adhesive resin layer 211 to facilitate gas emission.

[0112] The breathable resin layer 212 may contain fluorinated polyolefin resin, and preferably, may contain at least one of polytetrafluoroethylene (PTFE) or polyimide (PI).

[0113] The breathable resin layer 212 can have a thickness of 30 μm to 200 μm, specifically 40 μm to 150 μm, and more specifically 45 μm to 100 μm. When the thickness of the breathable resin layer 212 meets the above numerical range, the gas venting function can be performed smoothly even when the internal pressure of the pouch-type battery box 110 increases, without the gas venting section 200 detaching due to leakage.

[0114] On one hand, the breathable membrane 210 can have a thickness (T) of 80 μm to 500 μm, specifically 80 μm to 450 μm, 80 μm to 400 μm, 90 μm to 350 μm, and more preferably 100 μm to 300 μm. F When the above range is met, the thickness ratio of the adhesive resin layer 211 and the breathable resin layer 212 constituting the breathable membrane 210 can be easily adjusted, thereby facilitating designs that take into account adhesive strength and gas emission performance.

[0115] The thickness of the adhesive resin layer 211 (T) A ) and the thickness of the breathable resin layer 212 (T) T The ratio of (T) A / T T The ratio (T) can be 0.4 to 2.0, specifically 0.4 to 1.5, more specifically 0.4 to 1.2, and preferably 0.5 to 1.0. When the above ratio (T) A / T T When the above numerical range is met, it is easy to achieve gas discharge from the gas discharge section 200 while maintaining the adhesive strength, without causing permanent damage to the gas discharge section 200 due to leakage, and to minimize the pressure when the gas discharge section 200 starts operating. It is also desirable to meet the above range in the design of the gas permeability index.

[0116] Figure 5 According to an embodiment of the present invention, for example Figure 2 A plan view of a pouch-type secondary battery according to an embodiment, showing a configuration with three gas emission sections 200. (Refer to...) Figure 5 The gas emission section 200 can be provided on the platform section 150 where the electrode leads protrude, and an appropriate number of units in the range of 1 to 6 can be provided as described above. Furthermore, in Figure 5 In this case, the gas emission section 200 is only provided on the upper part of the platform section 150 based on the attached drawings, but the gas emission section 200 may also be provided on the lower part of the platform section 150, or on both the upper and lower parts.

[0117] Figures 6 to 8 yes Figure 5An enlarged plan view of region A, showing the enlarged area where the gas emission section 200 is located. (Refer to...) Figure 6 With three gas venting sections 200 provided, the factors included in the anti-leakage index as described above can be obtained. For example, the average radius (r) of the through-hole 220 in this figure. h ) can be accessed via (r) h1 +r h2 +r h3 The total cross-sectional area (A) of the 220-hole is obtained by dividing the area by 3. h ) can be achieved through πr h1 2 +πr h2 2 +πr h3 2 Obtain the total perimeter (C) of the 220mm through hole. h ) can be achieved through 2πr h1 +2πr h2 +2πr h3 The average width of the sealed area 230 can be obtained through (W) s1 +W s2 +W s3 ) / 3 is obtained, where W s1 W s2 and W s3 Each can be the average width of the sealing area surrounding each through-hole 220.

[0118] In addition, such as Figure 7 As shown, when the shape of the through-hole 220 is elliptical rather than circular, the average radius (r) h (r) can be obtained as the average of the major and minor axes, and therefore can be obtained through (r) hl +r hs To obtain it, use ) / 2. Additionally, as... Figure 8 As shown, when the through-hole 220 is a polygon, the average of the longest and shortest straight lines connecting the points and faces can also be used as the average radius (r) of the through-hole 220. h Therefore, in Figure 8 In the case of average radius (r) h ) can be accessed via (r) hl +r hs ) / 2 obtained.

[0119] The pouch-type battery case according to embodiment 1 has the gas venting section as described above, and therefore can operate at low operating pressures and exhibits a satisfactory level of gas venting performance, thereby withstanding high internal pressures and significantly improving durability. This can help increase service life, maintain battery operating performance through continuous gas venting, and ensure safety by stably venting gas while suppressing leakage.

[0120] Implementation Method 2

[0121] According to embodiment 2, the pouch-type battery box includes a cup-shaped portion having a receiving space for accommodating electrode assemblies, a platform portion formed along the periphery of the receiving portion, and a gas emission portion, wherein the gas emission portion is disposed in at least one of the cup-shaped portion or the platform portion, each gas emission portion includes at least one through hole, and the gas emission portion includes a breathable membrane covering the through hole, the breathable membrane including an adhesive resin layer and a breathable resin layer disposed on the adhesive resin layer, and each gas emission portion has a gas permeability index (GPI) of 0.05 to 0.55, as represented by Equation 2 below.

[0122] [Equation 2]

[0123] GPI = (A H x T A ) / (TS A x T F )

[0124] In equation 2 above, T F T is the total thickness (μm) of the breathable membrane given as a unitless number. A TS represents the thickness (μm) of the adhesive resin layer given as a unitless number. A The tensile strength of the adhesive resin layer given as a unitless number (kgf / mm) 2 ), and A H The area of ​​the through hole (mm²) is given as a unitless number. 2 ).

[0125] According to embodiment 2, a gas discharge section sealed with a breathable membrane can be provided, so that gas is discharged through a through hole formed in the pouch-shaped battery box, but the inflow and outflow of liquid are effectively prevented.

[0126] When gas passes through and is discharged through a permeable membrane covering the pores in the gas discharge section, the gas discharge performance and the inflow and outflow of liquids (moisture and electrolytes) are affected by the area of ​​the permeable section and the thickness of the permeable membrane, especially the proportion of the adhesive resin layer in the permeable membrane. Furthermore, the tensile strength of the permeable membrane affects the adhesive strength and gas permeability. Therefore, these design dimensions can be used as factors to define the permeability index.

[0127] As described above, the permeability index can be defined by using the design dimensions of the through-hole 220 and the breathable membrane 210 constituting the gas emission section 200 as factors.

[0128] The gas emission section 200 exhibits better gas emission performance as the area of ​​the through-holes 220 increases; however, increasing the area of ​​the through-holes 220 negatively impacts performance in preventing moisture penetration and electrolyte leakage. Conversely, reducing the area of ​​the through-holes 220 to prevent moisture penetration and electrolyte leakage may reduce gas emission performance and cause increased tension on the breathable membrane 210 during gas emission, which may impair adhesion to the pouch-type battery case 110. Therefore, the tensile strength of the adhesive resin layer 211 also needs to be considered to ensure that the breathable membrane 210 maintains adhesion while withstanding the tension generated by gas emission. Furthermore, a thinner breathable membrane 210 provides better gas emission performance, but reduced thickness may compromise adhesion, leading to problems with moisture penetration and electrolyte leakage prevention. Even when designed to be thinner, adhesion and gas emission performance may be affected by the thickness design of each of the adhesive resin layer 211 and the breathable resin layer 212.

[0129] Considering these characteristics, the present invention reflects the thickness (T) of the adhesive resin layer 211. A ) and the thickness of the entire breathable membrane 210 (T) F The ratio of (T) A / T F ) and the area of ​​through hole 220 (A) H The tensile strength (TS) of the adhesive resin layer 211. A By setting an appropriate permeability index value, the gas emission section is designed to minimize electrolyte leakage from the inside of the pouch battery box to the outside and to exhibit excellent emission performance during operation, while minimizing moisture penetration from the outside.

[0130] The air permeability index is 0.05 to 0.55, specifically, it can be greater than or equal to 0.08, greater than or equal to 0.10, greater than or equal to 0.15, or greater than or equal to 0.17, and it can also be less than or equal to 0.53, less than or equal to 0.50, or less than or equal to 0.48.

[0131] When the air permeability index is less than 0.05, the area of ​​the through hole 220 is less than the tensile strength of the adhesive resin layer 211, resulting in poor gas discharge performance. Therefore, due to the increase in internal pressure, it may not be able to prevent expansion. Furthermore, the thickness of the adhesive resin layer 212 is relatively too small, leading to durability problems and thus, leakage may occur due to the increase in internal pressure.

[0132] When the air permeability index is greater than 0.55, the tension applied to the breathable membrane 210 decreases as the area of ​​the through-holes 220 exceeds the tensile strength of the adhesive resin layer 211, thus ensuring durability. However, the thickness of the breathable resin layer 212 becomes relatively thin, raising concerns about significant moisture penetration from the outside, which could be accompanied by electrolyte leakage.

[0133] In the pouch-type battery box 110 according to embodiment 2, the gas emission section 200 can preferably be designed such that the air permeability index meets the above-mentioned range.

[0134] The pouch-type battery case according to embodiment 2 has a gas venting section as described above, and therefore can significantly improve the performance in preventing electrolyte leakage and moisture penetration while maintaining a satisfactory gas venting performance level. This prevents corrosion caused by the generated gas or by moisture penetration or electrolyte leakage, thereby contributing to increased service life due to increased durability. The battery's driving performance can be maintained through continuous gas venting, and the risk of explosion due to expansion is also reduced, thus ensuring safety.

[0135] Furthermore, the technical configurations and descriptions of the cup-shaped portion, platform portion, and gas emission portion constituting the pouch-type battery box, as well as the technical configurations and descriptions of the pouch film laminate as the material of the pouch-type battery box, can be applied in the same manner as in Embodiment 1, unless they are inconsistent with Embodiment 2.

[0136] Implementation Method 3

[0137] According to embodiment 3, the pouch-type battery box includes a cup-shaped portion having a receiving space for accommodating electrode assemblies, a platform portion formed along the periphery of the receiving portion, and at least one gas venting portion, wherein the gas venting portion is formed in at least one of the cup-shaped portion or the platform portion, each gas venting portion includes at least one through-hole and a breathable membrane covering the through-hole, the breathable membrane including an adhesive resin layer and a breathable resin layer disposed on the adhesive resin layer, the breathable membrane being sealed to the battery box to form a sealed area around the through-hole, and the gas venting portion having a water resistance index (WBI) of 2.0 to 10.5, as defined by Equation 3 below.

[0138] [Equation 3]

[0139] WBI = (A S x T F x T T ) / (A H x T A x 100)

[0140] In equation 3 above, A S It is the area of ​​the sealed region (mm) given as a unitless number. 2 ), T F T is the total thickness (μm) of the breathable membrane given as a unitless number. A T is the thickness (μm) of the adhesive resin layer given as a unitless number. T The thickness (μm) of the breathable resin layer is given as a unitless number, and A H The area of ​​the through hole (mm²) is given as a unitless number. 2 ).

[0141] According to embodiment 3, a gas discharge section sealed with a breathable membrane can be provided, so that gas is discharged through a through hole formed in the pouch-shaped battery box, but the inflow and outflow of liquid are effectively prevented.

[0142] When gas passes through the permeable membrane via the pores in the gas discharge section and is discharged, the gas discharge performance and the inflow and outflow of liquids (moisture and electrolytes) are affected by the area of ​​the permeable section, the total thickness of the permeable membrane, and the ratio of the thickness of the adhesive resin layer in the permeable membrane to the thickness of the permeable resin layer. Therefore, these design dimensions can be used as factors to define the water resistance index.

[0143] As described above, the water resistance index is defined by using the design dimensions of the through-hole 220 and the breathable membrane 210 that constitute the gas emission portion.

[0144] As the area of ​​the through-hole increases, the gas emission section 200 exhibits better gas emission performance, but increasing the area of ​​the through-hole 220 negatively impacts performance in preventing moisture penetration and electrolyte leakage. Regarding through-hole durability, the bonding area between the breathable membrane 210 and the pouch-type box 110, i.e., the sealing area, also needs to be considered, and therefore the area where the breathable membrane 210 contacts the pouch-type battery box 110 also needs to be considered. Furthermore, a thinner breathable membrane 210 provides better gas emission performance, but reduced thickness may compromise adhesion, leading to problems with moisture penetration and electrolyte leakage prevention. Even when designed thinner, adhesion, gas emission performance, moisture penetration, and electrolyte leakage prevention performance may be affected by the thickness design of each of the adhesive resin layer 211 and the breathable resin layer 212.

[0145] Taking these characteristics into account, the present invention reflects the thickness (T) of the adhesive resin layer 211 throughout the breathable membrane 210. A ) and the thickness of the breathable resin layer 212 (T) T The ratio of (T) A / T T ), the area of ​​the through hole 220 (A) H The area of ​​the sealed region in contact with the breathable membrane 210 and the pouch-type battery box 110 (A) S The ratio of ) and the total thickness of the breathable membrane 210 (T) F By setting an appropriate water resistance index value, the design of the gas emission section can minimize the leakage of electrolyte from the inside of the pouch battery box to the outside while maintaining gas emission performance, and also minimize the infiltration of moisture from the outside.

[0146] The water resistance index is less than or equal to 2.0, and for example, it can be greater than or equal to 2.3, greater than or equal to 2.5, greater than or equal to 3.0, and it can also be less than or equal to 10.0, less than or equal to 9.0, less than or equal to 8.0, less than or equal to 7.0, or less than or equal to 6.0.

[0147] When the water resistance index is less than 2.0, the bonding area (the area of ​​the sealed area) between the breathable membrane 210 and the pouch-type battery box 110 can be smaller than the area of ​​the through hole 220, and therefore moisture penetration or electrolyte leakage may occur, and the durability itself may be compromised.

[0148] When the water resistance index is greater than 10.5, the gas discharge performance may be impaired, leading to problems such as insufficient gas discharge speed to prevent expansion, relatively thin adhesive resin layer causing increased internal pressure leading to seal failure at certain points, and eventually gas leakage due to exceeding the adhesive strength limit.

[0149] In the pouch-type battery box 110 according to embodiment 3, the gas emission section 200 can preferably be designed such that the water resistance index meets the above-mentioned range.

[0150] The pouch-type battery box according to embodiment 3 has the gas venting section as described above, and therefore can significantly improve the performance in preventing electrolyte leakage and moisture penetration while maintaining a satisfactory gas venting performance level. This prevents corrosion caused by the generated gas or by moisture penetration or electrolyte leakage, thereby contributing to increased service life due to increased durability. The battery's driving performance can be maintained through continuous gas venting, and the risk of explosion due to expansion is also reduced, thus ensuring safety.

[0151] Furthermore, the technical configurations and descriptions of the cup-shaped portion, platform portion, and gas emission portion constituting the pouch-type battery box, as well as the technical configurations and descriptions of the pouch film laminate as the material of the pouch-type battery box, can be applied in the same manner as in Embodiment 1, unless they are inconsistent with Embodiment 3.

[0152] pouch-type secondary batteries

[0153] In another aspect, a pouch-type secondary battery 100 is provided, which includes an electrode assembly 160, a pouch-type battery case 110 as described above, an electrode lead 180 connected to the electrode assembly 160 and protruding to the outside of the pouch-type case 110 via a platform portion 150, and a lead film 190 disposed on the platform portion 150 between the electrode lead 180 and the pouch-type case 110, wherein a portion of the platform portion 150 is sealed along the periphery of the cup-shaped portions 122 and 132 to form a sealing portion 151.

[0154] Regarding the pouch-type battery case 110 and the gas emission section 200 disposed within the pouch-type battery case 110, the technical configurations and features corresponding to embodiments 1 to 3 can be applied to the aforementioned pouch-type secondary battery. Since the technical configurations and features are repeated with those described above, they will not be described in detail. Other components included in the pouch-type secondary battery 100 will be described below.

[0155] Electrode assembly

[0156] In one aspect, the electrode assembly 160 can be housed in the receiving portion 124 of the pouch-type battery box 110 and sealed by a sealing portion 151, which is formed by thermal fusion of the platform portion 150 after electrolyte injection.

[0157] The positive electrode, the separator, and the negative electrode can be stacked sequentially to form an electrode assembly 160. Specifically, the electrode assembly 160 may include two types of electrodes, a positive electrode and a negative electrode, and a separator sandwiched between the electrodes to insulate them from each other.

[0158] The positive and negative electrodes can have a current collector structure in which an active material slurry is applied to a metal foil or mesh containing aluminum and copper, respectively. Typically, granular active material, auxiliary conductor, binder, and conductive material are stirred together with added solvent to form a slurry. The solvent can be removed in subsequent processing.

[0159] A slurry mixed with electrode active materials, binders, and / or conductive materials can be applied to positive and negative current collectors to manufacture positive and negative electrodes, which are then stacked on both sides of a separator, thereby manufacturing the electrode assembly 160 into a predetermined shape. The type of electrode assembly 160 may include, but is not limited to, stacked, wound, and stacked and folded types.

[0160] Electrode assembly 160 may include electrode tabs 170.

[0161] Reference Figure 1 Electrode tab 170 is connected to each of the positive and negative electrodes of electrode assembly 160 and protrudes outward from electrode assembly 160, thus serving as a path for electrons to move between the inside and outside of the electrode tab. The current collector included in electrode assembly 160 may have a portion to which electrode active material is applied and an end portion to which no electrode active material is applied, i.e., an uncoated portion. Electrode tab 170 can be formed by cutting the uncoated portion, or by connecting individual conductive members to the uncoated portion using methods such as ultrasonic welding. Figure 1 As shown, electrode tab 170 can protrude from electrode assembly 160 in different directions, but is not limited thereto, and can be formed to protrude in various directions, such as protruding from one side in the same direction.

[0162] Electrode leads

[0163] In one aspect, the electrode lead 180 can supply power to the outside of the secondary battery 100. The electrode lead 180 can be connected to the electrode contacts 170 of the electrode assembly 160 by spot welding or the like.

[0164] Reference Figure 1 and Figure 3 The electrode lead 180 can be connected to the electrode assembly 160 and can protrude to the outside of the pouch battery case 110 via the platform portion 150. Specifically, one end of the electrode lead 180 can be connected to the electrode assembly 160, particularly to the electrode tab 170, and the other end of the electrode lead 180 can protrude to the outside of the pouch battery case 110 via the platform portion 150.

[0165] Electrode leads 180 may include a positive lead 182 and a negative lead 184. One end of the positive lead 182 is connected to the positive terminal 172 and extends in the direction in which the positive terminal 172 protrudes. One end of the negative lead 184 is connected to the negative terminal 174 and extends in the direction in which the negative terminal 174 protrudes. The other ends of both the positive lead 182 and the negative lead 184 may protrude to the outside of the battery case 110. Therefore, power generated inside the electrode assembly 160 can be supplied to the outside. Furthermore, the positive terminal 172 and the negative terminal 174 are each formed to protrude in various directions, and therefore, the positive lead 182 and the negative lead 184 may also extend in various directions. The positive lead 182 and the negative lead 184 may be made of different materials. In other words, the positive electrode lead 182 can be made of the same aluminum (Al) material as the positive current collector, and the negative electrode lead 184 can be made of the same copper (Cu) or nickel (Ni) coated copper material as the negative current collector. The portion of the electrode lead 180 protruding to the outside of the battery case 110 can be used as a terminal portion and electrically connected to an external terminal.

[0166] The side of the electrode lead 180 that is in direct contact with the lead film 190 and / or the gas emission portion 200 may be coated with at least one selected from chromium (Cr), nickel (Ni), alumina (Al2O3), zirconium (Zr)-based anhydride salts, and titanium (Ti)-based anhydride salts. In this case, corrosion resistance to the electrolyte solution and adhesion to the lead film 190 and / or the gas emission portion 200 can be obtained.

[0167] (5) Lead wire film

[0168] In one aspect, the lead film 190 prevents electricity generated from the electrode assembly 160 from flowing through the electrode leads 180 to the battery case 110 and allows the battery case 110 to remain sealed. For this purpose, the lead film 190 can be formed of a non-conductor having non-conductive properties in which current cannot flow well. Typically, a relatively thin insulating strip that is easily attached to the electrode leads 180 and / or the gas vent portion 200 is widely used as the lead film 190; however, embodiments of the invention are not limited to this, and therefore any component capable of insulating the electrode leads 180 can be used.

[0169] The lead film 190 can be configured to surround the outer peripheral surface of the electrode lead 180. The lead film 190 can be positioned within the platform portion 150 where the sealing portions 151 of the first box 120 and the second box 130 of the pouch-type battery box 110 are heat-fused, and can allow the electrode lead 180 to be bonded to the battery box 110.

[0170] The lead film 190 can be disposed between the electrode lead 180 and the pouch-type battery case 110. For example, as... Figure 3 As shown, the lower box 110, lead film 190, electrode lead 180, lead film 190 and upper box 110 can be stacked and arranged in the platform portion 150 in this order.

[0171] The lead film 190 may include at least one layer. Specifically, the lead film 190 may include a metal adhesive layer, a core layer, and a pouch adhesive layer stacked sequentially.

[0172] The metal adhesive 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 adhesive layer can comprise any material that readily adheres to the electrode lead 180. Specifically, the metal adhesive layer can comprise an acid-modified polyolefin. For example, the metal adhesive layer can comprise at least one of acid-modified polypropylene (PPa), acid-modified polyethylene (PEa), or plasma-treated polypropylene (PP), but is not limited thereto. The metal adhesive layer can have a thickness of 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 meets the above numerical range, it has the effect of preventing pinhole penetration and leakage at the edge portions during the fusion between the electrode lead and the lead film.

[0173] The core layer may be a layer disposed in the center of the lead film 190. The core layer may include, but is not limited to, additives such as polypropylene, polyolefin elastomer (POE), and / or colorants. In particular, the polymer contained in the core layer may be a homopolymer. When a homopolymer is included in the core layer, the melting point of the core layer can be controlled within the aforementioned numerical range, and heat-induced deformation can be minimized, which is better for ensuring insulation. The core layer may have a thickness of 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 meets the aforementioned numerical range, deformation caused by heat applied during fusion and sealing can be prevented, thereby producing a stable design effect in ensuring insulation.

[0174] The bag adhesive layer can be a layer in direct contact with the battery compartment 110, specifically a sealant layer of the bag film laminate. The bag adhesive layer can include, but is not limited to, polypropylene or polyolefin elastomer (POE). In particular, the polymer contained in the bag adhesive layer can be a copolymer. Ensuring sealable processability is better achieved by controlling the melting point of the bag adhesive layer containing the copolymer within the aforementioned numerical range, and by having a melting point similar to that of the polymer in the sealant layer of the bag film laminate. The bag adhesive layer can have a thickness of 40 μm to 100 μm, specifically 40 μm to 80 μm, more specifically 40 μm to 60 μm. When the thickness of the bag adhesive layer meets the aforementioned numerical range, it has the effect of ensuring that the residual amount of polymer (e.g., polypropylene) is sufficient to obtain the strength required for sealing between the electrode leads and the bag film laminate.

[0175] electrolytes

[0176] The pouch-type secondary battery 100 may further include an electrolyte (not shown) injected into the pouch-type battery case 110. The electrolyte is used to move lithium ions generated by electrochemical reactions at the electrodes during charging / discharging of the secondary battery 100, and may comprise a non-aqueous organic electrolyte solution as a mixture of lithium salt and organic solvent, or a polymer electrolyte. Additionally, the electrolyte may include a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a polymer-based solid electrolyte, and such solid electrolyte may be flexible and therefore easily deformable under external force.

[0177] The invention will be described in more detail below through specific embodiments. However, the examples shown below are for illustrative purposes only, and the scope of the inventive concept is not limited thereto. It will be apparent to those skilled in the art that various modifications and alterations can be made within the scope and technical range of the invention, and that such modifications and alterations fall within the scope of the claims contained herein.

[0178] Examples and Comparison Examples

[0179] A pouch-type secondary battery with a pouch-type battery case according to Embodiment 1

[0180] Examples 1a to 9a and comparison examples 1a to 7a

[0181] (1) Preparation of pouch-type battery box

[0182] A bag film laminate with a polyethylene terephthalate (PET) film and a nylon film of 266 mm width, 260 m length, and 60 μm thickness are stacked on one side of an aluminum alloy film. The PET film has a width of 266 mm, a length of 260 m, and a thickness of 12 μm, and the nylon film has a width of 266 mm, a length of 260 m, and a thickness of 25 μm. A polypropylene film with a width of 266 mm, a length of 260 m, and a thickness of 80 μm is stacked on the other side of the aluminum alloy film. In this case, the PET film and nylon film are the base layers, the aluminum alloy film is the gas barrier layer, and the polypropylene film is the sealant layer.

[0183] The pouch film laminate is molded to manufacture a pouch-type battery box including a receiving portion and a platform portion, and as... Figure 2 and Figure 3 As shown, a through hole is formed in the receiving portion (cup-shaped portion) adjacent to the platform portion, and as... Figures 4 to 6 The diagram shows a breathable membrane sealed inside the pouch-shaped battery compartment to form a gas venting section.

[0184] In this case, the gas emission section is designed as shown in Table 1 below, and as a breathable membrane, a 100 μm thick polytetrafluoroethylene (PTFE) layer is applied as a permeable resin layer, and a 100 μm thick acid-modified polypropylene (PPa) layer is applied as an adhesive resin layer.

[0185] (2) Manufacturing of pouch-type secondary batteries

[0186] The negative electrode, positive electrode, and porous polyethylene separator are assembled using a stacking method and then laminated to manufacture the electrode assembly. Electrode leads are then connected to the electrode assembly.

[0187] LiPF6 was dissolved in a solvent (EC:EMC:DMC = 3:3:4, volume ratio) to a concentration of 1.0 M to prepare the electrolyte. The electrode assembly was housed in a pouch-type box, with the front ends of the electrode leads protruding to the outside, and approximately 20 g of electrolyte was injected.

[0188] Then, a 200 μm thick lead film is stacked on each of the lower surface of the electrode leads and the upper surface of the gas emission section. The lead film may include a 75 μm thick metal adhesive layer of copolymer polypropylene and acid-modified polypropylene, a 65 μm thick core layer of homopolymer polypropylene, and a 60 μm thick bag adhesive layer of copolymer polypropylene.

[0189] Subsequently, the sealed portion of the pouch-type battery box was sealed for 2 seconds under conditions of a sealing strip area of ​​200 mm x 10 mm, 212°C and 0.27 MPa, and then placed at 60°C for 4 hours to manufacture the pouch-type secondary battery.

[0190] [Table 1]

[0191]

[0192] * π is omitted.

[0193] Experimental Example 1a: Assessment of Gas Emissions

[0194] To evaluate the performance of the gas venting section, the venting pressure was measured. Air was injected into the pouch-type secondary battery using an ITS pressure gauge to increase the internal pressure to 2.0 bar, and then the pressure was increased in increments of 0.5 bar. The pressure at which the gas venting section ruptured and all internal gas was released was measured to determine the venting pressure (bars). The results are shown in Table 2 below.

[0195] [Table 2]

[0196]

[0197] Referring to Table 2 above, in Examples 1a to 9a, the AVI value was met by precisely designing the gas discharge section to control the number and size of the orifices and the width of the sealing area, and correspondingly, the venting pressure was found to be greater than or equal to 5.0 bar. However, in Comparative Examples 1a to 7a, although the design dimensions were similar to those of the examples, the AVI value could not be met due to the lack of precise control, and therefore the venting pressure was found to be significantly reduced.

[0198] Therefore, it is determined that, as in the example with high venting pressure, when the gas venting section is designed and applied according to AVI, the gas venting section has excellent durability, and thus the gas is effectively vented even when a large amount of gas is generated from the battery, resulting in high venting pressure, thereby providing a lithium secondary battery exhibiting excellent durability and service life.

[0199] According to Embodiment 2, a pouch-type secondary battery with a pouch-type battery case

[0200] Examples 1b to 8b, Compare Examples 1b to 4b

[0201] (1) Preparation of pouch-type battery box

[0202] The pouch film laminate, manufactured in the same manner as in Example 1a, is molded to produce a pouch-type battery box including a receiving portion and a platform portion, and as... Figure 2As shown, a through hole is formed in the receiving portion (cup-shaped portion) adjacent to the platform portion, and a breathable membrane is thermally fused inside the pouch-shaped battery box to form a gas emission portion.

[0203] In this case, the gas emission section is designed as shown in Table 3 below. In Table 3 below, PP indicates polypropylene, PE indicates polyethylene, and PPa indicates acid-modified polypropylene.

[0204] (2) Manufacturing of pouch-type secondary batteries

[0205] Except for using the pouch-shaped battery case manufactured in (1) of Example 1b, the pouch-shaped secondary battery is manufactured in the same manner as in Example 1a.

[0206] [Table 3]

[0207]

[0208] * Adhesive layer: Adhesive resin layer; Permeable layer: Breathable resin layer

[0209] Experimental Example 1b: Assessment of Gas Emissions

[0210] The properties of the breathable membrane were determined and its performance evaluated using the following methods for the following items.

[0211] 1) Gas emission rate (cc / day): CO2 was injected into the bag-type secondary battery using a pressure device from ITS to increase the pressure inside the bag to 1.5 atm, and the gas emission rate was measured over 24 hours. The results are shown in Table 4 below.

[0212] 2) HF concentration (ppm): The pouch cell was placed at 60°C and 90% relative humidity for 16 weeks. Then the cell was opened and the HF concentration in the electrolyte (in ppm by weight) was measured to assess the degree of moisture penetration. The results are shown in Table 4 below.

[0213] [Table 4]

[0214]

[0215] Referring to Table 4 above, in the cases of Examples 1b to 8b with a permeability index of 0.05 to 0.55, it was determined that maintaining the emission rate at an appropriate speed prevents the bag-type secondary battery from expanding and prevents leakage, while also exhibiting excellent water permeability, thereby achieving an HF concentration of less than or equal to 800 ppm.

[0216] However, in Comparative Examples 1b to 3b, where the permeability index exceeds 0.55, it was determined that significant moisture permeation occurred, resulting in HF concentrations exceeding 900 ppm. Even with a guaranteed gas emission rate, moisture was observed to enter and exit, indicating poor long-term stability and thus hindering commercialization. Furthermore, in Comparative Example 4b, where the permeability index is less than 0.05, it was anticipated that even with a guaranteed level of moisture permeability performance, the gas emission rate would be too poor to prevent battery swelling or leakage.

[0217] Therefore, when designing the gas emission section of the pouch-type secondary battery according to an embodiment of the present invention, it is determined that by controlling factors to ensure that the air permeability index is within the range of 0.5 to 0.55, a gas emission section that exhibits excellent gas emission performance while ensuring a certain level of waterproof performance can be achieved.

[0218] According to Embodiment 3, a pouch-type secondary battery with a pouch-type battery case

[0219] Examples 1c to 9c, compare Examples 1c to 3c

[0220] (1) Preparation of pouch-type battery box

[0221] The pouch film laminate, manufactured in the same manner as in Example 1a, is molded to produce a pouch-type battery box including a receiving portion and a platform portion, and as... Figure 2 As shown, a through hole is formed in the receiving portion (cup-shaped portion) adjacent to the platform portion, and a breathable membrane is thermally fused inside the pouch-shaped battery box to form a gas emission portion.

[0222] In this case, the gas emission section is designed as shown in Table 5 below. In Table 5, PP indicates polypropylene, PE indicates polyethylene, and PPa indicates acid-modified polypropylene.

[0223] (2) Manufacturing of pouch-type secondary batteries

[0224] Except for using the pouch-shaped battery case manufactured in (1) of Example 1c, the pouch-shaped secondary battery is manufactured in the same manner as in Example 1a.

[0225] [Table 5]

[0226]

[0227] * Adhesive layer: Adhesive resin layer; Permeable layer: Breathable resin layer

[0228] Experimental Example 1c: Assessment of Gas Emissions

[0229] The properties of the breathable membrane were determined and its performance evaluated using the following methods for the following items.

[0230] 1) Gas emission rate (cc / day): CO is injected into the pouch cell using ITS's pressure equipment. 2 The pressure inside the bag was increased to 1.5 atm, and the gas emission was measured over 24 hours. The results are shown in Table 4 below.

[0231] 2) HF concentration (ppm): The pouch cell was placed at 60°C and 90% relative humidity for 16 weeks. Then the cell was opened and the HF concentration in the electrolyte (in ppm by weight) was measured to assess the degree of moisture penetration. The results are shown in Table 6 below.

[0232] [Table 6]

[0233]

[0234] As shown in Table 6 above, the Water Barrier Index (WBI) can be defined based on the thickness ratio of the adhesive resin layer and the breathable resin layer, as well as the ratio of the area of ​​the through-hole to the area of ​​the sealed area, thus reflecting the effectiveness of water blocking. In Examples 1c to 9c, it can be seen that when the WBI meets the range of 2.0 to 10.5, the water blocking performance is excellent, while the gas emission performance reaches a satisfactory level.

[0235] However, in Comparative Example 1c, where the WBI is less than 2.0, it is observed that while the overall thickness of the breathable membrane is thin, the breathable resin layer is thinner than the adhesive resin layer, and the design of the ratio of the sealed area to the pore area fails, resulting in poor gas emission performance and water permeability. Furthermore, Comparative Examples 2c and 3c have WBI values ​​greater than 10.5. To overcome the limitations of Comparative Example 1c, Comparative Example 2c was designed with a reduced pore area and increased sealing, but this was found to be excessive, to the point that the WBI value was not controlled, thus failing to address the water permeability problem despite the narrow pores. Additionally, Comparative Example 3c demonstrates that when the WBI value is not met, the balance between the deterioration of the emission rate due to increased membrane thickness and water permeability performance cannot be resolved.

[0236] [Explanation of reference numerals in the attached figures]

[0237] 100: Pouch-type secondary battery

[0238] 110: Pocket-type battery box

[0239] 111: Grassroots

[0240] 112: Gas Barrier Layer

[0241] 113: Sealant layer

[0242] 120: First box

[0243] 122: Cup-shaped part

[0244] 124: Containment section

[0245] 130: Second box

[0246] 132: Cup-shaped part

[0247] 140: Bridging section

[0248] 150: Platform Section

[0249] 151: Sealing part

[0250] 160: Electrode assembly

[0251] 170: Electrode contacts

[0252] 172: Positive electrode sheet

[0253] 174: Negative electrode sheet

[0254] 180: Electrode lead

[0255] 182: Positive lead

[0256] 184: Negative lead

[0257] 190: Lead film

[0258] 200: Gas Emissions Section

[0259] 210: Breathable membrane

[0260] 211: Adhesive resin layer

[0261] 212: Breathable resin layer

[0262] 220: Through hole

[0263] 230: Sealed area

Claims

1. A pouch-type battery box, comprising: The cup-shaped portion has a receiving space for accommodating the electrode assembly; The platform portion is formed along the periphery of the receiving portion; And the gas emission section, The gas emission portion is disposed in at least one of the cup-shaped portion or the platform portion, and each gas emission portion includes at least one through-hole and a breathable membrane covering the through-hole. The breathable membrane is sealed to the battery compartment to form a sealed area around the through-hole, and The gas emission section shown has a leak-proof index (AVI) of less than or equal to 3.0, which is defined by Equation 1 below: [Equation 1] AVI = [A h x r h ] / [W s x C h ] In Equation 1, A h It is the total cross-sectional area (mm²) of the through hole given as a unitless number. 2 ), r h W is the average radius (mm) of the through hole given as a unitless number. s It is the average width (mm) of the sealed area given as a unitless number, and C h It is the total circumference (mm) of the through hole given as a unitless number.

2. The pouch-type battery box according to claim 1, wherein, The air leak prevention index (AVI) is in the range of 0.10 to 2.

50.

3. The pouch-type battery box according to claim 1, wherein, The ratio of the average width of the sealing area of ​​the gas emission section to the average radius of the through hole is 0.45 to 3.

00.

4. The pouch-type battery box according to claim 1, wherein, The ratio of the total cross-sectional area of ​​the through-hole in the gas emission section to the total perimeter of the through-hole is between 0.25 mm and 2.50 mm.

5. The pouch-type battery box according to claim 1, wherein, The gas emission portion is formed at at least one location selected from the platform portion and the cup-shaped portion located adjacent to the platform portion and having no internal contact with the electrode assembly.

6. The pouch-type battery box according to claim 1, wherein, The number of through holes ranges from 1 to 6.

7. The pouch-type battery box according to claim 1, wherein, The through hole has a diameter of 5 mm. 2 Up to 25 mm 2 Total cross-sectional area (A) H ).

8. The pouch-type battery box according to claim 1, wherein, The breathable membrane has a thickness of 80 μm to 500 μm.

9. The pouch-type battery box according to claim 1, wherein, The breathable membrane is disposed inside the battery box.

10. The pouch-type battery box according to claim 1, wherein, The breathable membrane includes an adhesive resin layer in contact with the battery box and a breathable resin layer disposed on the adhesive resin layer.

11. The pouch-type battery box according to claim 10, wherein, The adhesive resin layer comprises a non-fluorinated polyolefin-based resin.

12. The pouch-type battery box according to claim 10, wherein, The breathable resin layer comprises a fluorinated polyolefin-based resin.

13. The pouch-type battery box according to claim 10, wherein, The thickness (T) of the adhesive resin layer A ) and the thickness of the breathable resin layer (T) T The ratio of (T) A / T T () in the range of 0.4 to 2.

0.

14. The pouch-type battery box according to claim 1, wherein, The pouch-type battery box has a structure in which a base layer, a gas barrier layer, and a sealant layer are stacked sequentially from the outside.

15. A pouch-type secondary battery, comprising: Electrode assembly; The pouch-type battery box according to claim 1; Electrode leads are connected to the electrode assembly and protrude to the outside of the pouch-shaped battery compartment via the platform portion; And a lead film, which is disposed on the platform portion between the electrode leads and the pouch-shaped battery box. A portion of the platform section is sealed along the periphery of the cup-shaped section to form a sealed portion.

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