Pouch film, manufacturing method thereof, pouch-type secondary battery case comprising same, and secondary battery

Abstract

The present invention relates to a pouch film, wherein the friction coefficient of a first outer layer and the surface roughness and friction coefficient of a sealant layer are controlled to specific ranges to improve the moldability of the film and prevent contamination of a molding mold / molding blocks, and wrinkles that can form at the edge of a bridge portion of a pouch-type secondary battery case product are suppressed to improve the quality of the product.

Description

Pouch film, method for manufacturing the same, pouch-type secondary battery case and secondary battery including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0102976, filed August 2, 2024, Korean Patent Application No. 10-2024-0201286, filed December 30, 2024, Korean Patent Application No. 10-2024-0201287, filed December 30, 2024, and Korean Patent Application No. 10-2024-0201288, filed December 30, 2024, the entire contents of which are incorporated herein by reference.

[0003]

[0004] Technology field

[0005] The present invention relates to a pouch film, a method for manufacturing the same, a pouch-type secondary battery case including the same, and a secondary battery.

[0006]

[0007] Secondary batteries can be repeatedly charged and discharged, and can be classified into cylindrical secondary batteries, prismatic secondary batteries, and pouch-type secondary batteries depending on their structure and manufacturing method. Among these, a pouch-type secondary battery is a type in which an electrode assembly (cell) is built into a pouch made of a metal laminate sheet. Its structure is relatively simple and its capacity per unit volume is relatively large, so it is widely used in energy storage devices such as automobile batteries. The pouch, which is the case of the pouch-type secondary battery, is manufactured by performing press processing on a flexible pouch film to form a cup portion. Then, once the cup portion is formed, the electrode assembly is accommodated in the receiving space of the cup portion, and the sealing portion is sealed to manufacture the secondary battery. In this way, the battery body sealed by the pouch film can be substantially free from exposure to the external environment.

[0008] Meanwhile, to prevent the battery body from being exposed to the external environment, the pouch film is required to have excellent sealing properties, and in particular, excellent sealing properties are required to be maintained under various environmental conditions. This is because exposure of the battery body to the external environment may result in problems such as a decline in the function of the pouch-type secondary battery or an explosion.

[0009] Here, the sealability and retention characteristics of the pouch film can be evaluated by the sealing strength of the pouch film. Sealing strength is an indicator of the superiority of the thermal bonding strength at the sealing portion of the pouch film. If the sealing strength of the pouch film is excellent, the sealability of the pouch film can generally be considered excellent.

[0010] Meanwhile, conventional pouch film products are manufactured using a slip agent on the pouch film. When the slip agent is used, slipperiness (slip property) can be imparted to the PP surface of the sealant layer and the PET surface of the outer protective layer during film extrusion and winding operations, thereby facilitating film forming. The slip agent may include an inorganic or polymeric lubricant. Among these, inorganic lubricants may cause defects such as insulation resistance when used in battery pouches, so it is more preferable to use a polymeric lubricant.

[0011] However, if the slip agent is used in excessive amounts, it has the problem of contaminating the mold / molding block of the film forming device. This contamination can cause cracks or fissures as foreign substances during the molding of the film product, and the contamination of the film forming device can cause damage. In addition, if the coefficient of friction is too low due to excessive slip agent, the pouch film is pushed into the mold during molding, causing wrinkles to form at the edge of the bridge portion, which can lower the insulation resistance and increase the incidence of insulation resistance defects, which can lower the completeness of the product.

[0012] In addition, if the slip agent is used in a minimum amount, the slip agent does not migrate initially, which increases the friction coefficient of the product, resulting in problems in molding, and as the working time passes, additional problems arise in that excessive slip agent causes contamination of the device.

[0013] Accordingly, a method is needed to improve the formability of a pouch film by controlling the amount of a slip agent and the coefficient of friction of the pouch film, to suppress contamination of a mold / molding block, and to suppress wrinkles occurring in the corner area of ​​the bridge portion of a pouch-type secondary battery case product, thereby improving the completeness of the product.

[0014] (Patent Document 1) KR 10-2024-0000780 A

[0015]

[0016] The problem to be solved by the present invention is to control the surface friction coefficient of the sealant layer and the first outer layer (outermost layer) within a specific range, and at the same time, control the surface roughness of the sealant layer to improve the formability of the pouch film, suppress contamination of the mold / molding block, and suppress wrinkles occurring in the corner area of ​​the bridge part of the pouch-type secondary battery case product, thereby providing a pouch film with a high degree of product completion and a pouch-type secondary battery case including the same.

[0017]

[0018] The present invention provides a pouch film, a method for manufacturing the same, a pouch-type secondary battery case including the same, and a secondary battery.

[0019] (1) The present invention provides a pouch film comprising a sealant layer, a barrier layer, a second outer layer, and a first outer layer sequentially laminated, wherein the sealant layer includes an activator, the friction coefficient of the first outer layer is 0.06 or more and 0.18 or less, the friction coefficient of the sealant layer is 0.10 or more and 0.20 or less, and the surface roughness Ra of the sealant layer is 0.065 or more and 0.120 or less.

[0020] (2) The present invention provides a pouch film in the above (1), wherein the active agent includes active agent A having a weight average molecular weight of 450 g / mol or less and active agent B having a weight average molecular weight of more than 450 g / mol.

[0021] (3) The present invention provides a pouch film in the above (2), wherein the active agent A includes at least one material selected from the group consisting of erucamide, oleamide, stearamide, and behenamide.

[0022] (4) The present invention provides a pouch film in (2) or (3), wherein the active agent B includes at least one material selected from the group consisting of ethylene bisoleamide and ethylene bissteramide.

[0023] (5) The present invention provides a pouch film in which the weight ratio of the active agent A and the active agent B is 1:0.43 or more and 2:30 or less in any one of the above (2) to (4).

[0024] (6) In any one of the above (1) to (5), the content of the active agent transferred to the surface of the sealant layer is 1.5 mg / m 2 Above 18.0 mg / m 2 A pouch film is provided as follows.

[0025] (7) In any one of (1) to (6), the content of the active agent included in the first outer layer is 1.5 mg / m 2 Above 12.0 mg / m 2 A pouch film is provided as follows.

[0026] (8) The present invention provides a pouch film according to any one of the above (1) to (7), wherein the sealant layer includes a polyolefin resin.

[0027] (9) The present invention provides a pouch film according to any one of the above (1) to (8), wherein the sealant layer includes a non-stretched polypropylene layer and an extrusion coating layer disposed between the non-stretched polypropylene layer and the barrier layer.

[0028] (10) The present invention provides a pouch film in any one of the above (1) to (9), wherein the first outer layer comprises at least one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber.

[0029] (11) The present invention provides a method for manufacturing a pouch film, comprising a step of surface treatment of both sides of a barrier layer, a step of laminating an outer layer on one side of the barrier layer, a step of laminating a sealant layer on the other side of the barrier layer to manufacture a film laminate, and a step of winding the film laminate at a winding pressure of 60 kgf or more and 150 kgf or less, wherein the sealant layer is heat-treated at a temperature of 40°C or more and 60°C or less for 4 days or more and 14 days or less after adding an activator of 800 ppm or more and 1400 ppm or less, and the sealant layer is manufactured so that the surface roughness Ra of the sealant layer is 0.065 or more and 0.120 or less.

[0030] (12) The present invention provides a method for manufacturing a pouch film, wherein, in the above (11), the active agent comprises active agent A having a weight average molecular weight of 450 g / mol or less and active agent B having a weight average molecular weight of more than 450 g / mol in a ratio of 1:0.43 or more and 2.30 or less.

[0031] (13) The present invention provides a pouch-type secondary battery case including a pouch film according to any one of (1) to (10).

[0032] (14) The present invention provides a pouch-type secondary battery case that does not include wrinkles according to the following conditions in the above (13).

[0033] [condition]

[0034] The above wrinkles are wrinkles created at the edge of the bridge portion when the pouch film is folded in half so that the cups are symmetrical and the sealant layers are in contact after forming two cups (size of 1 cup: width 158 mm × length 60 mm, depth: 9.5 mm) at regular intervals on the pouch film, and the depth of the wrinkles (the difference in height between the valleys and the ridges) is 100 ㎛ or more, and when the number of the wrinkles is 2 or more, the gap between the wrinkles (between the valleys) is 0.5 mm or more.

[0035] (15) The present invention provides a secondary battery including an electrode assembly formed by stacking a positive electrode, a separator, and a negative electrode, and a pouch-shaped battery case according to (14) for storing the electrode assembly.

[0036]

[0037] The present invention can provide a pouch film and a manufacturing method thereof with a high degree of product perfection by improving the formability of the pouch film, suppressing contamination of a mold / molding block, and suppressing wrinkles occurring in the corner area of ​​a bridge portion of a pouch-type secondary battery case product.

[0038]

[0039] Figure 1 is a schematic diagram showing the configuration of a pouch film according to Example 1 of the present invention.

[0040] Figure 2 is a photograph showing bubbles occurring in the bridge section after forming the cup section of the pouch film.

[0041] Figure 3 is a photograph showing that a phenomenon of slippage occurred at the side of the winding roll during the evaluation of the slippage in Experimental Example 6.

[0042] Figure 4 is a photograph showing wrinkles occurring at the edge of the bridge portion.

[0043]

[0044] Hereinafter, the present invention will be described in more detail to facilitate understanding. The terms and words used in this specification and claims should not be interpreted based on their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concepts of terms to best explain his or her invention, they should be interpreted in a way that aligns with the technical spirit of the present invention.

[0045] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0046] In this specification, it should be understood that the terms “include,” “comprising,” or “having” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0047] In the present specification, when each layer of the secondary battery pouch is included, it is not necessarily composed of only that layer, but additional layers may be included.

[0048] In this specification, being formed 'on' a specific layer includes not only being formed directly on that layer, but also being formed after interposing an additional layer.

[0049] In this specification, the extrusion coating (EC) layer refers to an extrusion layer of a resin, such as a polyolefin-based resin, preferably a polypropylene-based resin, that is extruded for bonding with a barrier layer as a part of the sealant layer. The extrusion coating (EC) layer of the sealant layer is located on the barrier layer side with respect to the polypropylene-based resin layer.

[0050] In this specification, the polypropylene (PP) layer of the sealant layer is a core resin layer forming the sealant layer and performs a sealing function, and may be formed of one or more layers made of polypropylene resin. It is in contrast to the aforementioned extrusion coating (EC) layer for bonding with the barrier layer, and is located on the inner side of the pouch film (i.e., the side opposite the barrier layer) based on the aforementioned extrusion coating (EC) layer.

[0051] In this specification, the “bridge portion” means a folded portion (line) formed when two cup portions are formed at a regular interval on a pouch film and folded so that the two cup portions are symmetrical to each other and the sealant layers are in contact, and the wrinkle in this specification means a wrinkle formed at the edge of the bridge portion. The wrinkle has a depth (the difference between the valley and the ridge) of 100 ㎛ or more, and when there are two or more wrinkles, the gap between the wrinkles (between the valleys) is 0.5 mm.

[0052]

[0053] pouch film

[0054] The present invention provides a pouch film comprising a sealant layer, a barrier layer, a second outer layer, and a first outer layer sequentially laminated, wherein the sealant layer includes an activator, the friction coefficient of the first outer layer is 0.06 or more and 0.18 or less, the friction coefficient of the sealant layer is 0.1 or more and 0.2 or less, and the surface roughness Ra (㎛) of the sealant layer is 0.065 or more and 0.120 or less.

[0055] The pouch film of the present invention comprises an inner sealant layer, an outer layer, and a barrier layer comprising aluminum between the inner sealant layer and the outer layer. The outer layer comprises a first outer layer and a second outer layer. The first outer layer may be the outermost layer, and the second outer layer may be disposed between the barrier layer and the first outer layer.

[0056] The surface friction coefficient of the sealant layer is 0.1 or more and 0.2 or less, and for example, the friction coefficient of the sealant layer may be 0.10 or more, 0.11 or more, 0.12 or more, 0.13 or more, 0.14 or more, 0.15 or more, 0.20 or less, 0.19 or less, 0.18 or less, 0.17 or less, or 0.16 or less. If the surface friction coefficient of the sealant layer is less than 0.1, wrinkles may occur during molding and the mold may be contaminated, causing problems in which the lubricant is transferred to the mold. The wrinkles may cause poor sealing and poor insulation resistance during cell manufacturing, and contamination of the mold may lower the quality of the manufactured secondary battery case, and may cause problems in that the mold must be cleaned frequently. In addition, if the surface friction coefficient of the sealant layer exceeds 0.2, it may be difficult to form to the intended forming depth because it is not slippery, and if it is not possible to form deeply, a problem of relatively low energy density may occur.

[0057] In addition, the surface friction coefficient of the first outer layer is 0.06 or more and 0.18 or less, and for example, may be 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.10 or more, 0.11 or more, 0.18 or less, 0.17 or less, 0.16 or less, 0.15 or less, 0.14 or less, 0.13 or less, or 0.12 or less. When the friction coefficient of the first outer layer exceeds 0.18, the first outer layer is not slippery, and thus a white line / wrinkle or bubble may be generated on the bridge portion due to the pressure applied to the bridge portion during 2-Cup molding. This may cause problems such as corrosion of the barrier layer during long-term use. In addition, when the friction coefficient of the first outer layer is less than 0.06, a problem of the tape peeling when bonding the tape for attachment between secondary battery cells may occur due to a large amount of lubricant transferred from the sealant layer to the first outer layer. This may cause the tape to fall during transportation after attachment between cells and may also lead to a fire. Here, the surface friction coefficient was measured using a friction coefficient measuring device (Labsink FPT-F1 (Friction Tester)), and two samples (Sample 1 and Sample 2) of each of the first outer layer or the sealant layer were prepared. After cutting and preparing Sample 1 (TD 120 mm x MD 250 mm) and Sample 2 (TD 65 mm x MD 120 mm), Sample 1 was fixed to the floor, Sample 2 was wrapped around a jig, and then placed on top of Sample 1. At this time, the jig weight is 200 g, the size is MD 54 mm x TD 55 mm, and the sample is measured at a speed of 100 mm / min, a measuring distance of 100 mm, and the coefficient of kinetic friction is determined from 20 to 100 mm among the measuring distances.

[0058]

[0059] In addition, the surface roughness Ra (㎛) of the sealant layer is 0.065 or more and 0.120 or less. The Ra refers to the center line average roughness among the surface roughness (surface roughness, Roughness). The surface roughness Ra is 0.09 or more and 0.30 or less. The Ra refers to the surface roughness among the surface roughness (surface roughness, Roughness). The surface roughness is measured using a laser roughness meter (OLYMPUS, OLS5100), with brightness 10, white light LED light source, 500x magnification, and a measurement area of ​​0.066 mm. 2Under the conditions, the surface roughness of five MD directions and five TD directions of the entire area of ​​the heat-sealing layer can be measured to calculate each surface roughness value. For example, the surface roughness Ra of the sealant layer may be 0.065 or more, 0.070 or more, 0.075 or more, 0.080 or more, 0.085 or more, 0.090 or more, 0.095 or more, 0.100 or more, 0.120 or less, 0.115 or less, 0.110 or less, and 0.105 or less. When the surface roughness value Ra falls within the above numerical range, it is possible to maintain excellent heat-sealing strength and insulation resistance characteristics, while reducing molding contamination during film molding, and to have excellent film moldability by providing an optimal friction coefficient. On the other hand, when the surface roughness Ra of the sealant layer is lower than the above range, a large amount of lubricant may be transferred from the sealant layer to the first outer layer during the winding process of the pouch film, which may cause a phenomenon in which the friction coefficient of the surface of the sealant layer increases and the friction coefficient of the surface of the first outer layer decreases. In addition, when the surface roughness Ra of the sealant layer is higher than the above range, the adhesive strength and insulation resistance values ​​may be significantly reduced, and it may not be easy to control the friction coefficient of the sealant layer and the first outer layer. The surface roughness may be controlled depending on the type of main resin of the sealant layer, the type of domain resin, the content and average particle size of the domain resin, the stretching pressure and temperature conditions, the type of lamination process, etc. during the manufacturing and lamination processes of the sealant layer.

[0060] In addition, the sealant layer of the pouch film of the present invention includes a lubricant. The lubricant can control frictional properties by imparting slipperiness to the surface of the sealant film and the surface of the outer layer film during the forming or winding process, and can prevent adhesion to the mold, thereby facilitating the forming of the pouch film.

[0061] According to one embodiment of the present invention, the active agent may include one or more substances selected from the group consisting of erucamide, oleamide, stearamide, behenamide, ethylene bisoleamide, and ethylene bissteramide.

[0062] According to one embodiment of the present invention, the content of the active agent transferred to the surface of the sealant layer is 1.5 mg / m 2 Above 26.0 mg / m 2 It may be less than or equal to. For example, the content of the active agent transferred to the surface of the sealant layer is 1.5 mg / m 2 Above, 2.0 mg / m 2 Above, 2.5 mg / m 2 Above, 3.0 mg / m 2 Above, 3.5 mg / m 2 Above, 4.0 mg / m 2 Above, 4.5 mg / m 2 Above 5.0 mg / m 2 Above, 5.5 mg / m 2 Above, 6.0 mg / m 2 Above, 6.5 mg / m 2 Above, 7.0 mg / m 2 Above, 7.5 mg / m 2 Above, 8.0 mg / m 2 Above, 8.5 mg / m 2 Above, 9.0 mg / m 2 Above, 9.5 mg / m 2 Above, 10.0 mg / m 2 Above, 26.0 mg / m 2 Below 25.0 mg / m 2 Below, 24.0 mg / m 2 Below, 23.0 mg / m 2 Below, 22.0 mg / m 2 Below, 21.0 mg / m 2 Below 20.0 mg / m 2 Below, 19.0 mg / m 2 Below, 18.0 mg / m 2 Below, 17.5 mg / m 2Below, 17.0 mg / m 2 Below, 16.5 mg / m 2 Below, 16.0 mg / m 2 Below, 15.5 mg / m 2 Below 15.0 mg / m 2 Below, 14.5 mg / m 2 Below, 14.0 mg / m 2 Below, 13.5 mg / m 2 Below, 13.0 mg / m 2 Below 12.5 mg / m 2 Below, 12.0 mg / m 2 Below, 11.5 mg / m 2 Below, 11.0 mg / m 2 Below 10.5 mg / m 2 It could be as follows:

[0063] According to one embodiment of the present invention, the content of the active agent included in the first outer layer is 1.5 mg / m 2 Above 12.0 mg / m 2 It may be less than or equal to 1.5 mg / m. For example, the content of the active agent included in the first outer layer is 1.5 mg / m. 2 Above, 2.0 mg / m 2 Above, 2.5 mg / m 2 Above, 3.0 mg / m 2 Above, 3.5 mg / m 2 Above, 4.0 mg / m 2 Above, 4.5 mg / m 2 Above 5.0 mg / m 2 Above, 5.5 mg / m 2 Above, 6.0 mg / m 2 Above, 6.5 mg / m 2 Above, 7.0 mg / m 2 Above, 12.0 mg / m 2 Below, 11.5 mg / m 2 Below, 11.0 mg / m 2 Below 10.5 mg / m 2 Below 10.0 mg / m 2 Below 9.5 mg / m 2 Below 9.0 mg / m2 Below 8.5 mg / m 2 Below 8.0 mg / m 2 Below 7.5 mg / m 2 It could be as follows:

[0064] When manufacturing a pouch film, an active agent is added to the sealant layer, and the active agent added to the sealant layer is transferred to the first outer layer during the winding process. In addition, the amount of the active agent added to the sealant layer transferred to the surface of the sealant layer and the amount transferred to the first outer layer may vary depending on the amount of active agent added, heat treatment time, heat treatment temperature, and winding pressure. The amount of the active agent transferred to the sealant layer and the amount of the active agent transferred to the first outer layer can be measured by the following method. The amount of the active agent was measured through gas chromatography (GC, Shimadzu GC2010 Plus). Specifically, n-hexadecane was used as an internal standard, and the internal standard was prepared with 50 ppmd of the standard substance using chloroform as a base. The above-mentioned active ingredient is diluted to 1, 5, 10, and 30 ppm in the internal standard material elution solution, and the standard solutions are set to 1, 5, 10, and 30 to prepare standard solutions, and the film is cut to 100 mm x 100 mm, then placed with the surface facing upward on the measurement jig, and the jig (jig diameter: 70 mm) is fastened. 5 ml of the internal standard material elution solution is dropped on the jig, and 2 ml is collected after 1 minute. After filtering with a PTFE filter, GC / FID is measured.

[0065]

[0066] If the above-mentioned active agent is added in excessive amounts, the formability is improved, but the sealing strength is reduced, and the winding state is poor, and the physical properties change over time, i.e., the change over time on the surface of the sealant layer and the first outer layer. In addition, since the degree of migration of the active agent varies depending on conditions such as temperature, pressure, and time, the physical properties of the pouch are not maintained uniformly. Furthermore, if the migration is excessive, it can cause foreign matter problems during the processing stage, which can be a factor that lowers the reliability of the product. On the other hand, if the above-mentioned active agent is included in an amount less than the above-mentioned range, the sealing strength is good, but the formability may be reduced.

[0067] That is, when the above-mentioned active agent is included in the above-mentioned range, the properties including the coefficient of friction of the sealant layer and the first outer layer of the pouch film can be uniformly controlled / maintained, thereby improving the formability in the process step, reducing contamination of the mold, preventing wrinkles in the bridge portion, and providing a high level of insulation resistance, and improving the completeness of the pouch-type secondary battery case product.

[0068] According to one embodiment of the present invention, the active agent may include an active agent A having a weight average molecular weight of 450 g / mol or less and an active agent B having a weight average molecular weight of more than 450 g / mol.

[0069] For example, the active agent A may include at least one substance selected from the group consisting of erucamide (molecular weight: 337.59 g / mol), oleamide (molecular weight: 281.48 g / mol), stearamide (molecular weight: 283.50 g / mol), and behenamide (molecular weight: 339.61 g / mol). In addition, the active agent B may include at least one substance selected from the group consisting of ethylene bisoleamide (molecular weight: 600.00 g / mol) and ethylene bissteramide (molecular weight: 596.03 g / mol).

[0070] According to one embodiment of the present invention, the weight ratio of the active agent A and the active agent B may be 3:7 to 7:3.

[0071] For example, the weight ratio of the activator A and the activator B may be 1: 0.43 or more, 0.45 or more, 0.47 or more, 0.50 or more, 0.53 or more, 0.55 or more, 0.57 or more, 0.60 or more, 0.63 or more, 0.65 or more, 0.67 or more, 0.70 or more, 0.75 or more, 0.80 or more, 0.85 or more, 0.90 or more, 0.95 or more, 1.00 or more, 2.30 or less, 2.1 or less, 2.0 or less, 1.7 or less, 1.5 or less, 1.3 or less, 1.1 or less. Depending on the molecular weight, the time taken for the sealant A to be included in the sealant layer and then derived to the surface may vary, and thus the friction coefficient of the surface of the manufactured sealant layer may vary. Accordingly, the ratio of low molecular weight and high molecular weight active agents included in the sealant layer may be an important factor. Accordingly, when the weight ratio of active agents A and B satisfies the above ratio, the surface friction coefficient of the sealant layer can be optimally controlled, the forming depth can be precisely formed according to the desired purpose, and the formability of the pouch film can be improved. If the content of active agent A is excessively high, the active agent may decompose during the high-temperature aging step after the winding process, which may excessively increase the friction coefficient of the sealant layer. If the content of active agent B is excessively high, the speed of transfer to the surface is significantly slowed, so that the time required for the aging step increases, and the friction coefficient of the sealant layer may excessively increase.

[0072]

[0073]

[0074] The above outer layer may be the outermost layer of the lithium secondary battery outer pouch film, and the outer layer may have an appropriate thickness within a range that can secure sufficient mechanical strength and sufficient formability as an outer material. For example, the thickness of the outer layer may be 15 ㎛ or more, 20 ㎛ or more, 25 ㎛ or more, 27 ㎛ or more, 35 ㎛ or more, 37 ㎛ or more, 70 ㎛ or less, 50 ㎛ or less, or 40 ㎛ or less. When the above range is satisfied, the insulation breakdown voltage can be maintained at a high level.

[0075] The outer layer may include a first outer layer and a second outer layer, and the first outer layer may include at least one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber.

[0076] In addition, the second outer layer, which is a heat-resistant resin layer having a melting point higher than the heat bonding temperature of the sealant layer, may include one or more compounds selected from the group consisting of polyamide-based compounds, polyester-based compounds, polyolefin-based compounds, and polyacrylic-based compounds.

[0077] According to one embodiment of the present invention, the outer layer may be formed of a laminated film of a first outer layer (polyethylene terephthalate) and a second outer layer (nylon). In this case, the thinner the first outer layer and the thicker the second outer layer, the more advantageous the formability. However, the thinner the first outer layer may be in terms of insulation breakdown voltage. From this point of view, for example, the thickness of the first outer layer may be 5 ㎛ or more, 7 ㎛ or more, 9 ㎛ or more, 10 ㎛ or more, 11 ㎛ or more, 12 ㎛ or more, 40 ㎛ or less, 39 ㎛ or less, 37 ㎛ or less, 35 ㎛ or less, 33 ㎛ or less, 31 ㎛ or less, 30 ㎛ or less, 29 ㎛ or more, 27 ㎛ or more, 25 ㎛ or less, 23 ㎛ or more, 20 ㎛ or less, 17 ㎛ or less, or 15 ㎛ or less. When the above first outer layer satisfies the above thickness range, the coating layer described above can effectively prevent external contamination while maintaining an excellent level of molding.

[0078] Additionally, the thickness of the second outer layer may be 10 µm or more, 12 µm or more, 15 µm or more, 17 µm or more, 20 µm or more, 40 µm or less, 37 µm or less, 35 µm or less, 30 µm or less, 27 µm or less, or 25 µm or less.

[0079] According to one embodiment of the present invention, the sealant layer may be the innermost layer of the pouch film for the external use of the lithium secondary battery. That is, the sealant layer may be in direct contact with the battery main body (e.g., electrode, separator, and / or electrolyte). Therefore, the sealant layer must have excellent electrolyte resistance and excellent insulation. To this end, according to one embodiment of the present invention, the sealant layer may include a polyolefin-based resin. The polyolefin-based resin has excellent electrolyte resistance and excellent insulation, and accordingly, the sealant layer including the polyolefin-based resin may also have excellent electrolyte resistance and excellent insulation derived from the polyolefin-based resin.

[0080] The polyolefin-based resin may include, for example, a polyolefin derived from an olefin or a derivative thereof, a copolymer thereof, or a blend comprising at least one of the foregoing. For example, the polyolefin-based resin may include at least one selected from the group consisting of polyethylene, polypropylene, polybutylene, a copolymer derived from a monomer derived from ethylene and / or propylene and a monomer derived from an alpha-olefin, or a blend thereof.

[0081] The thickness of the above sealant layer may be, for example, 20 ㎛ or more, 30 ㎛ or more, 40 ㎛ or more, 50 ㎛ or more, 100 ㎛ or less, 90 ㎛ or less, 80 ㎛ or less, 70 ㎛ or less, or 60 ㎛ or less, and when the above numerical range is satisfied, excellent electrolyte resistance and insulation may be achieved.

[0082] According to one embodiment of the present invention, the sealant layer may include a non-stretched polypropylene layer and an extrusion coating layer disposed between the non-stretched polypropylene layer and the barrier layer. For example, the sealant layer may be composed of a laminate of two or more layers in order to diversify functions. As a specific example, the sealant layer may include a first sealant layer disposed on the barrier layer, and a second sealant layer disposed on the first sealant layer. Here, the first sealant layer may be a layer (extrusion coating layer) that assists adhesion between the barrier layer and the second sealant layer while further enhancing the function as a sealant layer, and the second sealant layer may be a layer (non-stretched polypropylene layer) that constitutes the innermost sealant layer of the pouch film, and may be a layer that simultaneously seals and prevents leakage of a secondary battery, particularly a non-aqueous electrolyte. The first sealant layer may be an extrusion coating (abbreviated as EC) layer (mainly an extruded polypropylene layer), and the second sealant layer may be a polypropylene (PP) layer resin, preferably a non-stretched polypropylene (CPP) layer, located below the first sealant layer (inner side based on the pouch film). In this case, for example, the thickness of the non-stretched polypropylene (CPP) layer of the sealant layer may be, for example, 20 ㎛ or more, 30 ㎛ or more, 40 ㎛ or more, 50 ㎛ or more, 80 ㎛ or less, 70 ㎛ or less, or 60 ㎛ or less, and the thickness of the polypropylene (PP) layer of the sealant layer may be, for example, 0 ㎛ or more, 10 ㎛ or more, 20 ㎛ or more, 30 ㎛ or more, 60 ㎛ or less, 50 ㎛ or less, or 40 ㎛ or less.

[0083] Additionally, according to one embodiment of the present invention, the polypropylene (PP) layer of the sealant layer may contain various additives (rubber, elastomer, lubricant, etc.) depending on the required properties.

[0084] Meanwhile, the step of laminating the sealant layer to the barrier layer may be performed by an extrusion lamination method. For example, the method of laminating the sealant layer to the barrier layer may be performed by an extrusion lamination method and a solvent-dry lamination (SDL) method. Among these, the solvent-dry lamination method is a method of bonding a barrier layer (metal layer) to a polypropylene (PP) layer using a solvent-based adhesive and drying the solvent-based adhesive, and the sealant layer manufactured thereby is formed of a polypropylene (PP) layer.

[0085] In addition, the extrusion lamination method is a method of extruding a polyolefin resin, preferably a polypropylene resin, when adhering a polypropylene-based resin layer, preferably a non-stretched polypropylene (CPP) film, which is mainly used in the sealant layer, to the barrier layer (metal layer). As a result, the sealant layer can be formed of an extrusion coating (abbreviated as EC) layer (mainly an extruded polypropylene layer) and a polypropylene (PP) layer resin, preferably a non-stretched polypropylene (CPP) film, underneath it.

[0086]

[0087] In addition, the barrier layer may be an intermediate layer of the lithium secondary battery external pouch film (e.g., a layer disposed between the outer layer and the sealant layer) and may serve to prevent the intrusion of gas and / or moisture. The barrier layer is not particularly limited in type, but may include at least one selected from the group consisting of aluminum, stainless steel, copper, titanium, and alloys thereof, and specifically may include aluminum.

[0088] The above barrier layer may have an appropriate thickness within a range that can effectively prevent the intrusion of the aforementioned gas and / or moisture while ensuring sufficient formability. For example, the thickness of the barrier layer may be 40 ㎛ or more, 50 ㎛ or more, 55 ㎛ or more, 60 ㎛ or more, 150 ㎛ or less, 140 ㎛ or less, 130 ㎛ or less, 125 ㎛ or less, 120 ㎛ or less, 115 ㎛ or less, 110 ㎛ or less, 105 ㎛ or less, 100 ㎛ or less, 95 ㎛ or less, 90 ㎛ or less, 85 ㎛ or less, or 80 ㎛ or less.

[0089] According to one embodiment of the present invention, the maximum formable deformation length of the pouch film of the present invention may be 8 mm or more and 17 mm or less. For example, the maximum deformation length may be 8.0 mm or more, 8.5 mm or more, 9.0 mm or more, 9.5 mm or more, 10.0 mm or more, 10.5 mm or more, 11.0 mm or more, 11.5 mm or more, 12 mm or more, 12.5 mm or more, 13.0 mm or more, 13.5 mm or more, 14.0 mm or more, 14.5 mm or more, 15.0 mm or more, 17 mm or less, 16.5 mm or less, or 16 mm or less. The maximum forming length refers to the maximum height of the space in which the electrode assembly can be accommodated in the pouch film, and the present invention can implement an accurate deformation length by reducing the recovery force, and at the same time, implement a maximum deformation length compared to a conventional pouch film. If the maximum deformation length satisfies the above range, more electrode assemblies can be accommodated, which can have a superior level in terms of electrical capacity.

[0090]

[0091] Pouch film manufacturing method

[0092] The present invention provides a method for manufacturing a pouch film, comprising a step of surface treatment of both sides of a barrier layer, a step of laminating an outer layer on one side of the barrier layer, a step of laminating a sealant layer on the other side of the barrier layer to manufacture a film laminate, and a step of winding the film laminate, wherein the sealant layer is manufactured by heat-treating after adding an activator of 800 ppm or more and 1400 ppm or less.

[0093] The method for manufacturing the pouch film of the present invention can be performed by performing surface treatment on both sides of a barrier layer, laminating an outer layer of nylon and / or polyethylene terephthalate (PET) to one side of the barrier layer using an adhesive such as a polyolefin resin, and then laminating a polypropylene resin film, such as a non-stretched polypropylene resin (CPP) film, to the other side of the barrier layer through polypropylene resin extrusion to form a sealant layer.

[0094] The conventional method of manufacturing cell pouch films proceeds in the following order: outer layer surface treatment process, metal layer surface treatment process, outermost layer lamination process (outermost layer / metal layer), and sealant layer lamination process. In this case, since the order of coating, drying, and winding is repeated for each process, there was a problem that the probability of running loss and process defects occurring during the transport of each layer increased. In addition, since separate coating, drying, and winding tasks are sequentially performed in each process, the process is complicated, takes a lot of process time, and requires a device for coating, drying, and winding for each process, so there was a disadvantage that a lot of process facility space was taken up, reducing space efficiency.

[0095] In contrast, the method for manufacturing a pouch film of the present invention integrates the process of pretreating a metal fabric during the pouch manufacturing process into one process, and manufactures the pouch film using a double-sided double coating method in which the process of surface-treating both sides of the metal fabric is performed simultaneously, thereby improving product productivity and work space efficiency through process simplification.

[0096] In addition, an activator may be added to the sealant layer, specifically, the non-stretched polypropylene resin film, and the amount of the activator may be 800 ppm or more and 1400 ppm or less. For example, the amount of the activator may be 800 ppm or more, 850 ppm or more, 900 ppm or more, 950 ppm or more, 1000 ppm or more, 1050 ppm or more, 1100 ppm or more, 1400 ppm or less, 1350 ppm or less, 1300 ppm or less, 1250 ppm or less, or 1200 ppm or less.

[0097] The above winding process is a later step in the pouch film manufacturing process, and may be a preparatory process step for winding the film laminate into a roll form and storing, transporting, or proceeding to a subsequent processing process. The heat treatment may be performed at a temperature of 40°C or higher and 60°C or lower. For example, the heat treatment may be performed at a temperature of 40°C or higher, 41°C or higher, 42°C or higher, 43°C or higher, 44°C or higher, 45°C or higher, 46°C or higher, 47°C or higher, 48°C or higher, 49°C or higher, 50°C or higher, 60°C or lower, 59°C or lower, 58°C or lower, 57°C or lower, 56°C or lower, 55°C or lower, 54°C or lower, 53°C or lower, 52°C or lower, or 51°C or lower.

[0098] In addition, the heat treatment may be performed for 4 days or more and 14 days or less, and for example, may be performed for 4 days or more, 5 days or more, 6 days or more, 7 days or more, 14 days or less, 13 days or less, 12 days or less, 11 days or less, 10 days or less, 9 days or less, or 8 days or less.

[0099] In addition, the above-described winding step can be performed at a winding pressure of 60 kgf or more and 150 kgf or less, and for example, the winding pressure can be 60 kgf or more, 70 kgf or more, 80 kgf or more, 90 kgf or more, 100 kgf or more, 150 kgf or less, 140 kgf or less, 130 kgf or less, 120 kgf or less, or 110 kgf or less.

[0100] When manufacturing a pouch film, an active agent is added to the sealant layer, and during the winding process, the active agent added to the sealant layer is transferred to the first outer layer. The active agent added to the sealant layer may be an important factor in controlling the amount transferred to the surface of the sealant layer and the amount transferred to the first outer layer, depending on conditions such as the amount of active agent added, the heat treatment time, the heat treatment temperature, and the winding pressure. The method for manufacturing a pouch film of the present invention satisfies all of the ranges of the above-mentioned amount of addition, the heat treatment time, the heat treatment temperature, and the winding pressure, thereby applying the friction coefficient of the present invention to the sealant layer and the first outer layer, thereby suppressing contamination of the mold / molding block and suppressing wrinkles occurring in the corner area of ​​the bridge part of the pouch-type secondary battery case product, thereby providing a pouch film having high formability, excellent insulation resistance characteristics, and high degree of product completion, and a pouch-type secondary battery case including the same.

[0101]

[0102] Pouch-type secondary battery case and secondary battery

[0103] The secondary battery of the present invention includes a pouch-type secondary battery case including the battery main body and the pouch film laminate, and the battery main body is sealed by the pouch-type secondary battery case. For example, the secondary battery may be a lithium secondary battery, and in this case, the battery main body may include a lithium secondary battery negative electrode, a lithium secondary battery positive electrode, a separator, a current collector, and an electrolyte.

[0104] According to an embodiment of the present invention, a pouch-type secondary battery case including the pouch film of the present invention does not include wrinkles according to the above conditions at the edge portion of the bridge portion. The bridge portion is as described above in the preceding part of the present specification. In addition, the edge portion refers to both ends of the line / line when the bridge portion is in the form of a line / line, and the end portion refers to a radius of about 30 mm based on the line / line of the bridge portion. In addition, the wrinkles may be formed in multiple numbers, as shown in Fig. 4, and may be formed in a spiral or radial shape. The wrinkles may be caused when the pouch film is pushed into the press mold during molding due to an excessive amount of lubricant. In the present invention, the wrinkles refer to a case in which the height difference between the valleys and peaks of the wrinkles is 100 ㎛ or more, and if the number of wrinkles is two or more, the gap between the wrinkles (between valleys) is 0.5 mm or more.

[0105] The above wrinkles can cause problems that weaken the product's completeness after manufacturing the secondary battery, as they cause insulation resistance and increase the insulation resistance failure rate. Therefore, the pouch-type secondary battery case of the present invention is characterized by a technical feature that eliminates such wrinkles at the edge of the bridge portion by controlling the surface roughness of the sealant layer to a specific value.

[0106] The above lithium secondary battery positive electrode can be used without limitation as long as it is one that is commonly used as a positive electrode of a lithium secondary battery. For example, the above lithium secondary battery positive electrode can be used as one of LiCoO2, LiMnO2, LiFePO4, Li(Ni x Mn y Co z )O2(X+Y+Z=1), LiNiCoAlO2, etc. may be included as positive active materials.

[0107] The above electrolyte may include a lithium salt and a non-aqueous organic solvent. Here, the lithium salt and the non-aqueous organic solvent may be used without limitation as long as they are commonly used as electrolytes and organic solvents for lithium secondary batteries, respectively.

[0108] The above-mentioned negative electrode for a lithium secondary battery may be used without limitation as long as it is one that is commonly used as a negative electrode for a lithium secondary battery. For example, the above-mentioned negative electrode for a lithium secondary battery may include a negative electrode active material such as a carbon-based active material or a silicon-based active material.

[0109] The above pouch-type secondary battery case may have excellent sealing strength characteristics. Accordingly, the problem of the battery body sealed by the pouch-type secondary battery case being exposed to the external environment may not occur.

[0110]

[0111] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0112]

[0113] Example 1

[0114] A pouch film laminate was manufactured by laminating an outer layer, a barrier layer, and a sealant layer, wherein the outer layer is a laminated film of a polyethylene terephthalate (PET) film (first outer layer, thickness 12 ㎛) as the outermost layer and a nylon (Ny) film (second outer layer, thickness 25 ㎛) as the inner layer, aluminum is used for the barrier layer (thickness 60 ㎛), and the sealant layer (thickness 80 ㎛) includes a polypropylene extrusion coating (EC) layer (thickness 30 ㎛) and a non-stretched polypropylene film (CPP) (thickness 50 ㎛) using an extrusion lamination method. Here, the non-stretched polypropylene film (CPP) was added with 1000 ppm of an activator (activator A (erucamide, EBO):activator B (ethylene bisoleamide) = 3:7), and a winding process was performed on the pouch film laminate at a winding pressure of 120 kgf. After that, the pouch film laminate wound in a roll shape was aged at a temperature of 60°C for 4 days, thereby manufacturing a pouch film having a surface roughness (Ra) of the sealant layer of 0.065. At this time, the friction coefficients of the sealant layer and the first outer layer of the manufactured pouch film, and the activator contents of the first outer layer and the sealant layer are shown in Table 2.

[0115] Here, the surface friction coefficient was measured using a friction coefficient measuring device (Labsink FPT-F1 (Friction Tester)), and two samples (Sample 1 and Sample 2) of each of the first outer layer or sealant layer were prepared. After cutting and preparing Sample 1 (TD 120 mm x MD 250 mm) and Sample 2 (TD 65 mm x MD 120 mm), Sample 1 was fixed to the floor, and Sample 2 was wrapped around a jig and placed on top of Sample 1. At this time, the jig weighed 200 g, had a size of MD 54 mm x TD 55 mm, and the sample was measured at a speed of 100 mm / min, a measuring distance of 100 mm, and the kinetic friction coefficient was determined from 20 to 100 mm among the measuring distances.

[0116] In addition, the surface roughness was measured using a laser illuminance meter (OLYMPUS, OLS5100), brightness 10, white light LED light source, 500x magnification, and measurement area 0.066mm. 2 Under the conditions, the surface roughness of five MD directions and five TD directions of the entire area of ​​the thermal bonding layer was measured to calculate the surface roughness values ​​for each.

[0117]

[0118] Examples 2 to 10

[0119] A pouch film was manufactured in the same manner as in Example 1, except that the surface roughness (Ra) of the sealant layer and the ratio of lubricants A and B were changed as described in Table 1 below. At this time, the friction coefficients of the sealant layer and the first outer layer of the manufactured pouch film, the content of the lubricant of the first outer layer, and the content of the lubricant of the sealant layer are shown in Table 2.

[0120]

[0121] Comparative Examples 1 to 12

[0122] A pouch film was manufactured in the same manner as in Example 1, except that the surface roughness (Ra) of the sealant layer and the ratio of lubricants A and B were changed as described in Table 1 below. At this time, the friction coefficients of the sealant layer and the first outer layer of the manufactured pouch film, the content of the lubricant of the first outer layer, and the content of the lubricant of the sealant layer are shown in Table 2.

[0123]

[0124] ClassificationActivator input amount (ppm)Winding pressure (kgf)Temperature (℃)Time (day)Surface roughness (Ra)Activator ratio (Activator A:Activator B)Example 110001206040.0653:7Example 210001206040.0654:6Example 310001206040.0655:5Example 410001206040.0656:4Example 510001206040.0657:3Example 610001206040.1203:7Example 710001206040.1204:6Example 810001206040.1205:5Example 910001206040.1206:4 Example 1010001206040.1207:3 Comparative Example 110001206040.0650:10 Comparative Example 210001206040.0651:9 Comparative Example 310001206040.0652:8 Comparative Example 410001206040.0658:2 Comparative Example 510001206040.0659:1 Comparative Example 610001206040.06510:0 Comparative Example 710001206040.1200:10 Comparative Example 810001206040.1201:9 Comparative Example 910001206040.1202:8Comparison Example 1010001206040.1208:2Comparison Example 1110001206040.1209:1Comparison Example 1210001206040.12010:0

[0125] Experimental Example 1 - Measurement of mold contamination

[0126] After preparing a specimen with a size of MD 300 mm X TD 400 mm, molding was performed using a 2-cup molding machine. The cup part was molded with a size of 158 mm X 60 mm and a depth of 9.5 mm, and the pressure was set to 0.7 MPa. Before molding measurement, the mold was wiped with ethanol and then molding was measured. During the measurement, the occurrence of wrinkles in the bridge part was checked, and the point in time (number of hits) when wrinkles occurred was determined as the number of molding contamination hits. For example, if wrinkles in the bridge part occurred after 1,500 molding hits, the number of molding contamination hits is determined to be 1,500 hits. Under the above conditions, if the number of contamination hits is less than 3,000 hits during molding, it is considered NG.

[0127]

[0128] Experimental Example 2 - Forming Depth Evaluation

[0129] For the pouch films manufactured in the above examples and comparative examples, specimens with a size of MD 300 mm X TD 400 mm were prepared, and then molding was performed using a 2-cup molding machine. The cup part was 158 mm X 60 mm in size, and the pressure was set to 0.7 MPa to measure the molding depth. When molding, molding was started from a molding depth of 8.0 mm, and if no cracks occurred out of 10, molding was performed by increasing the depth by an additional 0.5 mm. The above process was repeated, and the maximum depth without cracks, which is the depth obtained by subtracting 0.5 mm from the molding depth at which cracks occurred, was used as the molding depth. If the molding depth is less than 9.5 mm under the above conditions, it was considered NG.

[0130]

[0131] Experimental Example 3 - Insulation Resistance Evaluation

[0132] 1000 30 mm x 40 mm dummy cells (small cells) containing the pouch films of the above examples and comparative examples were manufactured, and 250 V was applied to the aluminum tab portion and the aluminum layer (barrier layer) portion of the pouch using an insulation resistance meter to measure the insulation resistance value (GΩ). If it was 100 MΩ or less, it was recorded as defective (NG), thereby calculating the defect rate. If insulation resistance occurs under the above conditions, it is considered NG.

[0133]

[0134] Experimental Example 4 - Measuring the amount of active agent

[0135] The amount of the above-mentioned active agent was measured through gas chromatography (GC, Shimadzu GC2010 Plus). Specifically, n-hexadecane was used as an internal standard, and an internal standard was prepared with 50 ppmd of the standard substance using chloroform as a base. The above-mentioned active agent raw material was diluted to 1, 5, 10, and 30 ppm in the internal standard material elution solution, and the standard solutions were prepared by setting the standard solutions to 1, 5, 10, and 30. After cutting the film to 100 mm x 100 mm, the surface was placed upward on a measuring jig, and the jig (jig diameter: 70 mm) was fastened. 5 ml of the internal standard material elution solution was dropped on the jig, and 2 ml was collected after 1 minute. After filtering through a PTFE filter, GC / FID was measured. The specific conditions of the GC measurement equipment are as follows.

[0136] (1) Column: HP-5 (30 m × 0.25 mm × 0.25 ㎛, Agilent)

[0137] (2) Gas flow rate

[0138] · Carrier gas (He): 1 mL / min (27.5 cm / sec)

[0139] · Make-up gas (He): 30 mL / min

[0140] · Hydrogen: 40 mL / min

[0141] · Air: 400 mL / min

[0142] (3) Oven temperature program

[0143] · Initial temperature: 100℃ (maintained for 3 minutes)

[0144] · Rising speed: 15℃ / min

[0145] · Final temperature: 310℃ (maintained for 20 minutes)

[0146] (4) Injection conditions

[0147] · Injection temperature: 250℃

[0148] · Injection split ratio: 1 / 20

[0149] · Injection volume: 1 ㎕

[0150] (5) Detector conditions

[0151] · Detector temperature: 310℃

[0152] (6) Analysis time

[0153] Total analysis time: 37 minutes

[0154]

[0155] Experimental Example 5 - Evaluation of Bridge Bubble Generation

[0156] After preparing a specimen with a size of MD 300 mm X TD 400 mm, molding was performed using a 2-Cup molding machine. The cup part was molded with a size of 158 mm X 60 mm and a depth of 9.5 mm, and the pressure was set to 0.7 MPa. Before molding measurement, the mold was wiped with ethanol and then molded. If a bubble was generated in the bridge part after the measurement, it was considered NG. A bubble refers to a lifting between the first outer layer and the second outer layer or between the second outer layer and the barrier layer, and a bubble is defined as a lifting with a diameter of 30 μm or more. Fig. 2 shows an actual example of a bubble generated in the bridge part.

[0157]

[0158] Experimental Example 6 - Evaluation of winding slippage

[0159] When manufacturing the pouch film of the above examples and comparative examples, the winding cross-section was checked after the slitter (short material) process, and if the winding was pulled out by 1 mm or more at the side edge of the roll as shown in Fig. 3, it was evaluated as having a winding pull-out. Fig. 3 is a photograph showing that a pull-out phenomenon occurred at the side edge of the winding roll during the evaluation of winding pull-out in Experimental Example 6.

[0160]

[0161] Experimental Example 7 - Pressure Test

[0162] When manufacturing the pouch films of the above examples and comparative examples, after the slitter (short material) process, the film was placed on a winding tester and the cross-section of the winding roll was pushed with a force of 50 kg. If the winding came off, it was evaluated as NG. Figure 4 is a photograph of the tester used in the winding test of Experimental Example 7.

[0163]

[0164] Experimental Example 8 - Evaluation of Wrinkle Occurrence in the Bridge Area

[0165] In the pouch film manufactured in the above examples and comparative examples, 2 cups (size of 1 cup: width 158 mm × length 60 mm, depth: 9.5 mm) were formed at regular intervals, and when the pouch film was folded in half so that the cups were symmetrical and the sealant layers were in contact, it was visually checked whether wrinkles occurred at the edge of the bridge portion and its surroundings. If there were no wrinkles, it was indicated as X, if the wrinkle height was less than 100 ㎛, it was indicated as △, if the wrinkle height was 100 ㎛ or more, it was indicated as ○, and if there were two or more wrinkles with a wrinkle height of 100 ㎛ or more, it was indicated as ◎.

[0166]

[0167] Classification Wrinkle occurrenceFriction coefficientLubricant content (mg / m2)Molding contaminationNumber of hitsMolding depth (mm)Insulation resistance (number of defectives)Bridge part bubble occurrence (number of bubbles)Winding offWinding pressure test (50kg)Sealant layer 1st outer layerSealant layer 1st outer layerExample 1X0.20.181.51.79000 hits or more9.500No OKExample 2X0.190.173.12.69000 hits or more9.500No OKExample 3X0.190.153.44.385009.500No OKExample 4X0.170.138.06.070001000No OKExample 5X0.150.113.08.560001100No OKExample 6X0.190.183.51.59000 strokes or more9.500No OKExample 7X0.180.175.52.79000 strokes or more9.500No OKExample 8X0.180.156.44.59000 strokes or more1000No OKExample 9X0.160.1410.55.19000 strokes or more1100No OKExample 10X0.140.1315.46.3800011.500No OKComparative Example 1X0.300.250.40.39000 strokes or more7014Yes OKComparative Example 2X0.280.210.60.59000 strokes or more8010Yes OKComparative Example 3△0.220.191.11.29000 strokes or more903NoOKComparison Example 4○0.120.0620.411.940001100NoNGComparison Example 5◎0.080.0530.212.8200011.5320NoNGComparison Example 6◎0.060.0435.213.150011.5460NoNGComparison Example 7X0.290.240.50.49000 strokes or more7012YesOKComparison Example 8X0.270.210.70.59000 strokes or more809YesOKComparison Example 9△0.230.20.90.89000 strokes or more905NoOKComparison Example 10○0.140.0715.410.840001100No NGComparative example 11◎0.090.0526.512.8250011.5270No NGComparative example 12◎0.070.0430.916.1150011.5430No NG

[0168] Referring to Tables 1 and 2 above, in the case of the examples including the content of the active agent transferred to the surface of the sealant layer of the pouch film and both active agents A and B, the molding contamination count is high and the molding depth is also deep, confirming excellent molding and low contamination. In addition, the defect rate of insulation resistance is significantly low, the phenomenon of winding slippage is suppressed, the winding pressure is high, and the occurrence of bubbles and wrinkles in the bridge portion after molding is suppressed, so that the completion and quality of the product can be significantly improved.

[0169] On the other hand, in the case of comparative examples in which the content range of the lubricant transferred to the surface of the sealant layer is outside the scope of the present invention, it is difficult for the molding depth to reach the target depth, the bubble generation rate in the bridge part increases, the winding pressure decreases, or the winding slip phenomenon occurs, thereby lowering the product completion and quality. In addition, it was confirmed that at least one wrinkle occurred at the edge of the bridge part. In particular, in the case of comparative examples 1 and 7 that do not include lubricant A, the molding depth is significantly reduced, resulting in inferior moldability, and the bubble generation rate in the bridge part is high, resulting in significantly lower product completion. In addition, in the case of comparative examples 6 and 12 that do not include lubricant B, the molding contamination number is too low, resulting in severe contamination of the mold and molding device, and the insulation resistance and winding pressure are significantly inferior.

[0170]

[0171]

[0172] Acknowledgement

[0173] The present invention is a result of the following task support.

[0174] [Project ID] 2410004468

[0175] [Assignment Number] 20022450

[0176] Ministry of Trade, Industry and Energy

[0177] [Name of Project Management (Specialist) Institution] Korea Institute of Industrial Technology Planning and Evaluation

[0178] [Research Project Name] Material and Components Technology Development (Leeum Company)

[0179] [Research Project Name] Development of a Next-Generation Secondary Battery Pouch Capable of Delivering More Than Double the Highest Adhesive Strength (60°C)

[0180] [Contribution rate] 1 / 1

[0181] [Name of Project Performing Organization] Yulchon Chemical Co., Ltd.

[0182] Research Period: January 1, 2024 - December 31, 2024

Claims

1. Contains a sealant layer, a barrier layer, a second outer layer, and a first outer layer sequentially laminated, The above sealant layer contains an activator, The friction coefficient of the first outer layer is 0.06 or more and 0.18 or less, The coefficient of friction of the above sealant layer is 0.10 or more and 0.20 or less, A pouch film having a surface roughness Ra of the sealant layer of 0.065 or more and 0.120 or less.

2. In claim 1, A pouch film comprising an activator A having a weight average molecular weight of 450 g / mol or less and an activator B having a weight average molecular weight of more than 450 g / mol.

3. In claim 2, A pouch film wherein the above active agent A comprises at least one substance selected from the group consisting of erucamide, oleamide, stearamide, and behenamide.

4. In claim 2, A pouch film wherein the above active agent B comprises at least one material selected from the group consisting of ethylene bisoleamide and ethylene bissteramide.

5. In claim 2, A pouch film wherein the weight ratio of the above-mentioned active agent A and active agent B is 1:0.43 or more and 2.30 or less.

6. In claim 1, The content of the above-mentioned active agent transferred to the surface of the above-mentioned sealant layer is 1.5 mg / m 2 Above 18.0 mg / m 2 Pouch film as follows.

7. In claim 1, The content of the above-mentioned active agent included in the above-mentioned first outer layer is 1.5 mg / m 2 Above 12.0 mg / m 2 Pouch film as follows.

8. In claim 1, A pouch film wherein the sealant layer comprises a polyolefin resin.

9. In claim 1, A pouch film wherein the sealant layer comprises a non-stretched polypropylene layer and an extrusion coating layer disposed between the non-stretched polypropylene layer and the barrier layer.

10. In claim 1, A pouch film wherein the first outer layer comprises at least one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber.

11. Surface treatment step on both sides of the barrier layer; A step of laminating an outer layer to one surface of the above barrier layer; A step of manufacturing a film laminate by laminating a sealant layer on the other surface of the barrier layer; and A step of winding the above film laminate at a winding pressure of 60 kgf or more and 150 kgf or less, A method for manufacturing a pouch film, wherein the sealant layer is heat-treated at a temperature of 40°C to 60°C for 4 to 14 days after adding an activator of 800 ppm to 1400 ppm, so that the surface roughness Ra of the sealant layer is 0.065 to 0.

120.

12. In claim 11, A method for manufacturing a pouch film, wherein the above-mentioned active agent comprises active agent A having a weight average molecular weight of 450 g / mol or less and active agent B having a weight average molecular weight of more than 450 g / mol in a ratio of 1:0.43 or more and 2.30 or less.

13. A pouch-type secondary battery case including a pouch film according to claim 1.

14. In claim 13, A pouch-type secondary battery case that does not include wrinkles according to the following conditions. [condition] The above wrinkles are wrinkles created at the edge of the bridge portion when the pouch film is folded in half so that the cups are symmetrical and the sealant layers are in contact after forming two cups (size of 1 cup: width 158 mm × length 60 mm, depth: 9.5 mm) at regular intervals on the pouch film, and the depth of the wrinkles (the difference in height between the valleys and the ridges) is 100 ㎛ or more, and when the number of the wrinkles is 2 or more, the gap between the wrinkles (between the valleys) is 0.5 mm or more.

15. An electrode assembly formed by stacking a positive electrode, a separator, and a negative electrode; and A secondary battery comprising a pouch-shaped battery case according to claim 14 for storing the electrode assembly.

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