Pouch film laminate, pouch-type battery case, and pouch-type secondary battery

Abstract

The present invention includes sequentially laminated substrate layers, a gas barrier layer, and a sealant layer, wherein the sealant layer is represented by the following [Formula 1] f T The present invention relates to a pouch film laminate in which the value of is 0.32 to 3.1, and the surface roughness (Ra) of the sealant layer is 0.11 μm to 0.75 μm. [Equation 1]f T =f T2 / f T1 In the above [Equation 1], f T1 This is the coefficient of friction of the sealant layer at T1, and f T2 is the coefficient of friction of the sealant layer at T2, where T1 and T2 are different temperatures.

Description

[Technical Field]

[0001] This application claims priority under Korean Patent Application No. 10-2023-0120750 dated September 11, 2023, the entirety of which is incorporated herein by reference.

[0002] The present invention relates to a pouch film laminate, a pouch-type battery case, and a pouch-type secondary battery. More specifically, it relates to a pouch film laminate, a pouch-type battery case, and a pouch-type secondary battery in which moldability is improved by having a coefficient of friction within a predetermined range regardless of temperature. [Background technology]

[0003] Rechargeable batteries are used not only in small products such as digital cameras, P-DVDs, MP3 players, mobile phones, PDAs, portable game devices, power tools, and e-bikes, but also in large products requiring high output, such as electric vehicles and hybrid vehicles, as well as in power storage devices and backup power storage devices that store surplus generated power and new / renewable energy.

[0004] Typically, secondary batteries are manufactured by applying an electrode active material slurry to a positive electrode current collector and a negative electrode current collector to produce the positive and negative electrodes, stacking them on both sides of a separator to form an electrode assembly of a predetermined shape, then housing the electrode assembly in a battery case, injecting the electrolyte, and finally sealing it.

[0005] Rechargeable batteries are classified into pouch type and can type depending on the material of the case that houses the electrode assembly. Pouch type batteries house the electrode assembly in a pouch made of a flexible polymer material. Can type batteries house the electrode assembly in a case made of a material such as metal or plastic.

[0006] A pouch-type battery case is manufactured by press-forming a flexible pouch film laminate to form a cup portion. Once the cup portion is formed, an electrode assembly is placed in the storage space of the cup portion, and the seal portion is sealed to manufacture a secondary battery.

[0007] In such press forming processes, drawing molding is performed by inserting a pouch film into a press machine and applying pressure to the pouch film laminate with a punch to stretch the laminate. Generally, a pouch film laminate is formed from multiple layers, with a polymer film such as polyethylene terephthalate laminated on one side of a metal gas barrier layer and a sealant layer laminated on the other side.

[0008] In recent years, as the demand for high-capacity batteries such as electric vehicle batteries and ESS batteries has increased, there has been a growing need for battery cases that can accommodate more electrode assemblies. Therefore, attempts have been made to increase the molding depth of the cup portion of a pouch-type battery case, or to increase the volume of the cup portion by molding cup portions in both the upper and lower cases using a two-cup molding method.

[0009] In conventional manufacturing of laminated pouch films, to prevent adhesion between the pouch films and facilitate subsequent processing, a lubricant was either included in the innermost sealant layer of the pouch film or a lubricant was applied to the surface of the sealant layer. However, at high temperatures, the lubricant would penetrate into the interior of the sealant layer, resulting in its loss.

[0010] Therefore, there is a need to develop a pouch film laminate that prevents adhesion between pouch film laminates regardless of temperature, allows for easy processing in subsequent steps, and does not crack even when the molding depth of the cup portion is increased. [Overview of the project] [Problems that the invention aims to solve]

[0011] The present invention is for solving the foregoing problems, and provides a pouched film laminate that prevents adhesion between pouched film laminates regardless of temperature, has a small change in coefficient of friction according to temperature, and is excellent in formability, a pouched battery case, and a pouched secondary battery.

[0012] The problems of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

Means for Solving the Problems

[0013] [1] The present invention includes a base material layer, a gas barrier layer, and a sealant layer laminated in sequence, and the value of f represented by the following [Formula 1] in the sealant layer is 0.32 to 3.1, and the surface roughness (Ra) of the sealant layer is 0.11 μm to 0.75 μm, and provides a pouched film laminate. T2

[0014] [Formula 1] f T =f T2 / f T1

[0015] In the above [Formula 1], f T1 is the coefficient of friction of the sealant layer at T 1, f T2 is the coefficient of friction of the sealant layer at T 2, and the T ,1 and the T 2 are different temperatures.

[0016] [2] In the present invention according to [1] above, the value of f T may be 0.33 to 3.0.

[0017] [3] In the present invention according to [1] or [2] above, the T 1 may be 25° C., and the T 2 may be any one of the temperatures from 0° C. to 125° C. excluding 25° C.

[0018] ​[4] In at least one of the above [1] to [3], T1 may be 25°C and T2 may be 60°C.

[0019] [5] In at least one of the above [1] to [4], the surface roughness (Ra) of the sealant layer may be 0.16 μm to 0.55 μm.

[0020] [6] In at least one of the above [1] to [5], the sealant layer may include a positive-etching protrusion.

[0021] [7] In at least one of the above [1] to [6], the coefficient of friction of the sealant layer at 60°C may be 0.38 or less.

[0022] [8] In at least one of the above [1] to [7], the value of D represented by the following [Formula 2] of the pouch film laminate T may be 0.82 to 1.22.

[0023] [Formula 2] D T = D <000001><00001><00001><00001><00001><00001><00001>[[ID=2,8]] / D T1,a In the above [Formula 2], D T1,a is the forming depth at which cracks occur when the pouch film laminate is cut into a size of 300 mm × 400 mm at T1,a and then formed into a shape having two cup portions with a size of 90 mm in width and <000001><00001><00001><00001><00001><00001><00001>60 mm in length, and D T2,a is the forming depth at which cracks occur when the pouch film laminate is cut into a size of 300 mm × 400 mm at T2,a and then formed into a shape having two cup portions with a size of 90 mm in width and <000001><00001><00001><00001><00001><00001><00001>60 mm in length, and T1,a and T2,a are different temperatures.

[0024] [9] In at least one of the above [1] to [8], the base material layer may have a laminated structure of a polyethylene terephthalate film and a nylon film.

[0025]

[10] In at least one of the above [1] to [9], the thickness of the gas barrier layer may be 20 μm to 100 μm.

[0026]

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

[10] , the thickness of the sealant layer may be 30 μm to 130 μm.

[0027]

[12] The present invention provides a pouch-type battery case manufactured by drawing-molding the pouch film laminate described in [1] above.

[0028]

[13] The present invention provides a pouch-type rechargeable battery including the battery case described in

[12] above. [Effects of the Invention]

[0029] The sealant layer contained within the pouch film laminate according to the present invention has a friction coefficient within a predetermined range regardless of temperature, and also has a surface roughness (Ra) within a predetermined range. Therefore, even when the lubricant on the surface of the sealant layer penetrates into the interior of the sealant layer at high temperatures, it prevents the blocking phenomenon where the pouch film laminates come into contact with each other, and also provides excellent moldability. Furthermore, using the pouch film laminate according to the present invention reduces the molding defect rate depending on the storage temperature and aging period of the pouch film laminate, and allows for shipment without aging after manufacturing the pouch film laminate, and since temperature control is not required, process efficiency is improved. [Brief explanation of the drawing]

[0030] The drawings accompanying this specification illustrate preferred embodiments of the present invention and, together with the aforementioned description of the invention, serve to further illustrate the technical concept of the present invention. Therefore, the present invention should not be construed as being limited solely to the matters depicted in such drawings. Furthermore, the shapes, sizes, scales, proportions, etc., of elements in the drawings included in this specification may be exaggerated to emphasize a clearer explanation.

[0031] [Figure 1] This is a cross-sectional view of a pouch film laminate according to one embodiment of the present invention. [Figure 2] This is an exploded assembly diagram of a secondary battery according to one embodiment of the present invention. [Figure 3] This figure shows that no damage occurred to the pouch when the pouch film laminate manufactured according to Example 1 was stored at 60°C before pouch molding. [Figure 4] This figure shows the damage to the pouch that occurred when the pouch film laminate manufactured according to Comparative Example 3 was stored at 60°C before pouch molding. [Modes for carrying out the invention]

[0032] The present invention will be described in more detail below.

[0033] The terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical concept of the present invention, in accordance with the principle that inventors can appropriately define the concepts of terms in order to best describe their invention.

[0034] In this invention, the MD direction (Machine Direction) refers to the longitudinal direction of the pouch film laminate, and the TD direction (Transverse Direction) refers to the width direction of the pouch film laminate.

[0035] In this invention, the surface roughness (Ra) was measured using an optical measuring instrument (NV-2700, Optical Profiler, manufactured by Nano System Inc.). The lens used was Lens i20X, with an FOV of 1.0X (FOV ~316μm × 237μm), and the measurement was performed using WSI envelope mode. Specifically, the sacn range was 10μm upper / lower, and the surface roughness was measured at seven points in each 2D topo image (316μm × 237μm) taken at arbitrary points on the sample. Subsequently, the mean and standard deviation were calculated for the values ​​at five points excluding the maximum and minimum values.

[0036] The inventors of the present invention conducted extensive research to address the problems of lubricant penetration into the sealant layer at high temperatures and problems arising during the manufacturing and storage of pouch film laminates by the roll-to-roll process. As a result, they discovered that by controlling the ratio of friction coefficients of the sealant layer within the pouch film laminate at different temperatures to a predetermined range, and by controlling the surface roughness of the sealant layer to a predetermined range, excellent moldability is achieved regardless of temperature, thus completing the present invention.

[0037] The present invention will be described in detail below.

[0038] The pouch film laminate, pouch-type battery case, and pouch-type secondary battery according to the present invention include at least one of the configurations disclosed below, and may include any combination of technically feasible configurations from the following configurations.

[0039] Pouch film laminate Figure 1 shows one embodiment of the pouch film laminate according to the present invention. The pouch film laminate according to the present invention will be described below with reference to Figure 1.

[0040] Referring to Figure 1, the pouch film laminate 1 according to the present invention includes sequentially laminated base layer 10, gas barrier layer 20, and sealant layer 30, wherein the sealant layer 30 is represented by the following [Formula 1] fT The value is 0.32 to 3.1, and the surface roughness (Ra) of the sealant layer 30 is 0.11 μm to 0.75 μm.

[0041] [Formula 1] f T =f T2 / f T1

[0042] In the above [Equation 1], f T1 This is the coefficient of friction of the sealant layer at T1, and f T2 is the coefficient of friction of the sealant layer at T2, where T1 and T2 are different temperatures.

[0043] In conventional manufacturing of pouch film laminates, to prevent adhesion between pouch films and facilitate subsequent processing, a lubricant was either included in the innermost sealant layer of the pouch film or a lubricant was applied to the surface of the sealant layer to control the coefficient of friction. However, at high temperatures, the lubricant would penetrate into the interior of the sealant layer, causing it to disappear and resulting in a rapid increase in the coefficient of friction of the sealant layer. This increase in the coefficient of friction caused problems such as cracks occurring in the pouch during the molding of the cup portion of the pouch-type battery case, making it impossible to increase the molding depth of the cup portion. Furthermore, the disappearance of the lubricant led to a blocking phenomenon where the pouch film laminates would come into contact with each other during storage.

[0044] Therefore, the inventors have repeatedly developed a pouch film laminate that prevents adhesion between pouch film laminates even at high temperatures, allows for easy processing in subsequent steps, and does not crack even when the molding depth of the cup portion is increased. As a result, they have found that when the friction coefficient of the sealant layer is controlled within a predetermined range at different temperatures, and the surface roughness of the sealant layer is controlled within a predetermined range, the laminate exhibits excellent moldability regardless of temperature, and more specifically, excellent moldability even at high temperatures.

[0045] f represented by [Equation 1] above TThe value may be, in detail, 0.32 or greater, 0.322 or greater, 0.324 or greater, 0.326 or greater, 0.328 or greater, or 0.33 or greater, and may also be 3.1 or less, 3.09 or less, 3.08 or less, 3.07 or less, 3.06 or less, 3.05 or less, 3.04 or less, 3.03 or less, 3.02 or less, 3.01 or less, or 3.0 or less.

[0046] Furthermore, in the above [Equation 1], T1 and T2 are different temperatures. Preferably, T1 is 25°C and T2 is any temperature between 0°C and 125°C, excluding 25°C; more preferably, T1 is 25°C and T2 is any temperature between 40°C and 125°C; even more preferably, T1 is 25°C and T2 is any temperature between 50°C and 125°C; and even more preferably, T1 is 25°C and T2 is 60°C.

[0047] said f T If the value of is less than 0.32 or greater than 3.1, the coefficient of friction of the sealant layer will differ significantly at different temperatures, resulting in a problem of reduced moldability with temperature, and a blocking phenomenon will occur where the pouch film laminates come into contact with each other, causing problems with processability. Therefore, the above f T When the value of satisfies the above range, the friction coefficient of the sealant layer can be appropriately adjusted at different temperatures, resulting in excellent moldability regardless of temperature and eliminating the need to adjust the temperature, thus offering superior processability.

[0048] The sealant layer 30 is represented by the following [Equation 1-1] f 60,25 The value may be between 1.00 and 3.15, more specifically between 1.5 and 3.1, more specifically between 1.80 and 3.05, and even more specifically between 2.0 and 3.0.

[0049] [Formula 1-1] f 60,25 =f 60℃ / f 25℃ In the above [Equation 1-1], f 60℃This is the coefficient of friction of the sealant layer at 60°C, and f 25℃ This is the coefficient of friction of the sealant layer at 25°C.

[0050] said f T This can be adjusted in various ways, such as by adjusting the amount of lubricant contained in the sealant layer, the melting point of the lubricant, the mixing ratio of the lubricant, or the surface roughness (Ra) of the sealant layer, but by adjusting the surface roughness (Ra) of the sealant layer, the aforementioned f T It is preferable to adjust the value to an appropriate range.

[0051] Furthermore, the surface roughness (Ra) of the sealant layer 30 is 0.11 μm to 0.75 μm. Preferably, it is 0.12 μm to 0.72 μm, more preferably 0.13 μm to 0.70 μm, even more preferably 0.14 μm to 0.65 μm, even more preferably 0.15 μm to 0.60 μm, and most preferably 0.16 μm to 0.55 μm.

[0052] When applying a roll-to-roll process for the mass and high-speed production of pouch film laminates, after producing the pouch film laminates but before forming the pouch mold cases, the pouch film laminates are stored in a kind of roll shape, where a rectangular parallelepiped is wound up in one direction. In this case, the sealant layer 30 located at the bottom end of the pouch film laminate exhibits a roll shape in contact with the base material layer 10 due to its wound shape.

[0053] Here, if the surface roughness (Ra) of the sealant layer 30 is less than 0.11 μm, the low surface roughness increases the contact area with the substrate layer, causing the lubricant on the surface of the sealant layer 30 to migrate to the surface of the substrate layer, further reducing the amount of lubricant on the surface of the sealant layer 30. Furthermore, when stored at high temperatures as well as at room temperature, the solubility of the lubricant on the surface of the sealant layer 30 increases, causing an even larger amount of lubricant to migrate to the surface of the substrate layer. This increases the coefficient of friction at room temperature, resulting in a large change in the coefficient of friction with temperature, and an increase in the fluctuation of the coefficient of friction with temperature changes. In that case, the maximum molding depth decreases with temperature changes, resulting in the disadvantage that the maximum molding depth decreases depending on the storage and / or transport method of the pouch film laminate.

[0054] Furthermore, if the surface roughness (Ra) of the sealant layer 30 exceeds 0.75 μm, the high surface roughness reduces the contact area with the base material layer, thereby reducing the amount of lubricant on the surface of the sealant layer 30 that migrates to the surface of the base material layer 10. On the other hand, when forming a pouch-type case, the sealant layer 30 abuts against one end of the jig, and the base material layer 10 abuts against the portion opposite to the end. However, as described above, the amount of lubricant that migrates to the surface of the base material layer 10 decreases, increasing the friction coefficient of the base material layer 10, which reduces the maximum molding depth. Also, if the surface roughness is too high, the friction coefficient increases due to the anchor effect, which reduces moldability. In that case, the maximum molding depth decreases with temperature changes, and the maximum molding depth decreases depending on the storage and / or transport method of the pouch film laminate, which are disadvantages.

[0055] Therefore, when the above range is met, a joint is instantaneously formed when the two surfaces are bonded together, and the sticking phenomenon that occurs when the joint repeatedly comes into contact and separates during sliding does not occur, and an appropriate coefficient of friction can be maintained, resulting in excellent moldability. Furthermore, because the degree of unevenness is not excessive, moldability does not decrease regardless of temperature, and when performing a roll-to-roll process, the amount of lubricant present on the surfaces of the sealant layer 30 and the base layer 10 can be appropriately controlled to achieve excellent moldability, as well as excellent insulation and sealing properties.

[0056] The sealant layer 30 may include embossed or intaglioted protrusions, and is preferably embossed. In the case of embossed protrusions, the embossed protrusions can be formed by inserting particles with different average particle sizes into the surface layer of the sealant layer, which offers excellent processability in terms of easy adjustment of surface roughness.

[0057] The sealant layer 30 may have a coefficient of friction of 0.20 or less at 25°C, preferably 0.01 to 0.15, more preferably 0.01 to 0.13, even more preferably 0.01 to 0.12, and even more preferably 0.02 to 0.11. When the above range is met, the coefficient of friction of the sealant layer is sufficiently low even at room temperature, resulting in excellent moldability and preventing the blocking phenomenon where the pouch film laminates stick together. Furthermore, because the coefficient of friction of the sealant layer does not change significantly with temperature, it offers excellent moldability and processability.

[0058] The sealant layer 30 may have a coefficient of friction of 0.38 or less at 60°C, preferably 0.01 to 0.35, more preferably 0.05 to 0.33, and even more preferably 0.05 to 0.30. When the above range is met, the coefficient of friction of the sealant layer is sufficiently low even at high temperatures, resulting in excellent moldability and preventing the blocking phenomenon where the pouch film laminates stick together. Furthermore, because the coefficient of friction of the sealant layer does not change significantly with temperature, it offers excellent moldability and processability.

[0059] The sealant layer 30 may contain a lubricant. The lubricant is not particularly limited as long as it can provide slipperiness, but for example, it may be erucamide. When the lubricant is included, the whitening phenomenon that appears in the sealant layer can be prevented, and contamination that occurs during the molding process can be prevented.

[0060] The sealant layer 30 does not necessarily have to include a lubricant layer to which a lubricant is applied. Conventionally, an additional step of applying a lubricant was sometimes added to increase moldability or maintain slipperiness, but the sealant layer according to the present invention can exhibit excellent slipperiness and moldability even without including the lubricant layer, so it does not need to include the lubricant layer. As a result, processability can be improved because there is no additional step of applying a lubricant, and contamination that occurs during the molding process can be prevented.

[0061] On the other hand, the pouch film laminate is represented by D [Formula 2] below. T The value may be between 0.82 and 1.22, preferably between 0.85 and 1.2, more preferably between 0.9 and 1.1, and even more preferably between 0.94 and 1.06.

[0062] [Formula 2] D T =D T2,a / D T1,a In the above [Equation 2], D T1,a This is the molding depth at which cracks occur when the pouch film laminate is cut to a size of 300 mm x 400 mm at T1,a and then molded to have two cup sections measuring 90 mm wide x 160 mm long, and D T2,a T1,a and T2,a are different temperatures at which cracks occur when the pouch film laminate is cut to a size of 300 mm x 400 mm at T2,a and then molded to have two cup sections measuring 90 mm wide x 160 mm long.

[0063] Here, T1,a is 25°C and T2,a may be any temperature between 0°C and 125°C except 25°C, preferably T1,a is 25°C and T2,a is any temperature between 40°C and 125°C, more preferably T1,a is 25°C and T2,a is any temperature between 50°C and 125°C, and even more preferably T1,a is 25°C and T2,a is 60°C.

[0064] The following describes in detail each layer of the pouch film laminate according to the present invention.

[0065] (base material layer) The base layer 10 is placed on the outermost layer of the battery case to protect the electrode assembly from external impacts and to provide electrical insulation.

[0066] In one example, the base layer 10 may have a laminated structure of polyethylene terephthalate (PET) film (12) and nylon film (14). Here, it is preferable that the nylon film (14) is placed on the gas barrier layer 20 side, i.e., the inside, and the polyethylene terephthalate film (12) is placed on the surface side of the battery case.

[0067] Polyethylene terephthalate (PET) has excellent durability and electrical insulation properties, so when a PET film is placed on the surface side, it provides excellent durability and insulation. However, in the case of PET film, the adhesion to the aluminum alloy thin film that constitutes the gas barrier layer 20 is weak, and the stretching behavior is different. Therefore, when the PET film is placed on the gas barrier layer side, delamination occurs between the base layer and the gas barrier layer during the molding process, and the gas barrier layer does not stretch uniformly, resulting in a decrease in moldability. In contrast, nylon film has a similar stretching behavior to the aluminum alloy thin film that constitutes the gas barrier layer 20, so when a nylon film is placed between polyethylene terephthalate and the gas barrier layer, an improvement in moldability can be obtained.

[0068] The polyethylene terephthalate film may have a thickness of 5 μm to 20 μm, preferably 5 μm to 15 μm, and more preferably 7 μm to 15 μm. The nylon film may have a thickness of 20 μm to 40 μm, preferably 20 μm to 35 μm, and more preferably 25 μm to 35 μm. When the thicknesses of the polyethylene terephthalate film and the nylon film meet the above ranges, the moldability and rigidity after molding are excellent.

[0069] (Gas barrier layer) The gas barrier layer 20 is laminated between the substrate layer 10 and the sealant layer 30 to ensure the mechanical strength of the pouch, block the entry and exit of gases and moisture from the outside of the secondary battery, and prevent electrolyte leakage from inside the pouch-type battery case.

[0070] The gas barrier layer 20 may be formed of a metal. For example, the gas barrier layer may be a thin metal film containing one or more metals selected from the group consisting of aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti), and Invar (INVAR), but is not limited thereto.

[0071] According to one embodiment of the present invention, the gas barrier layer 20 may be formed from an aluminum alloy thin film. When the gas barrier layer 20 is formed using an aluminum alloy thin film, it is possible to ensure mechanical strength above a predetermined level, while also ensuring light weight, complementation of electrochemical properties by the electrode assembly and electrolyte, and heat dissipation. The aluminum alloy thin film may contain elements other than aluminum (Al). For example, the aluminum alloy thin film may contain one or more elements selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0072] As another example, the gas barrier layer 20 may be formed from a stainless steel thin film. Specifically, the gas barrier layer 20 may be manufactured by molding and / or processing a stainless steel thin film. Because the gas barrier layer 20 formed from stainless steel has relatively low thermal conductivity, it is effective in preventing or delaying heat diffusion to other cells during thermal runaway, and because it has relatively high toughness, it can suppress the occurrence of cracks in the pouch during use of the pouch-type battery. Stainless steel may contain one or more elements other than iron (Fe), such as copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0073] The thickness of the gas barrier layer 20 may be 20 μm to 100 μm, preferably 30 μm to 90 μm, and more preferably 40 μm to 85 μm. In this invention, the problem of deformation of the base layer does not occur even when the sealing temperature is increased so that heat is transferred to the sealant layer, so it is possible to improve moldability and gas barrier performance when forming the cup portion using a gas barrier layer thicker than conventional gas barrier layers.

[0074] (Sealant layer) The sealant layer 30 is intended to completely seal the inside of the pouch-type battery case, which houses the electrode assembly inside, by being heat-bonded to each other at the sealing portion when the pouch-type battery case is sealed. For this purpose, the sealant layer 30 may be formed from a material having excellent heat-bonding strength.

[0075] The sealant layer 30 may be formed from a material having insulating, corrosion-resistant, and sealing properties. Specifically, since the sealant layer 30 is in direct contact with the electrode assembly and / or electrolyte inside the pouch-type battery case, it may be formed from a material having insulating and corrosion-resistant properties. Also, since the sealant layer 30 must completely seal the inside of the pouch-type battery case and block the movement of substances between the inside and outside, it may be formed from a material having high sealing properties (e.g., excellent thermal adhesion strength). To ensure such insulating, corrosion-resistant, and sealing properties, the sealant layer 30 may be formed from a polymer material.

[0076] The sealant layer 30 may consist of one or more substances selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyarylate, and Teflon®, and is preferably composed of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In that case, the polypropylene may consist of unoriented polypropylene (Cast Polypropylene, CPP), acid-modified polypropylene (PPA), polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene ternary copolymer.

[0077] The thickness of the sealant layer 30 may be 30 μm to 130 μm, preferably 40 μm to 120 μm, and more preferably 60 μm to 100 μm. When the thickness of the sealant layer satisfies the above range, it has the effect of ensuring the moldability of the pouch film laminate while ensuring the seal strength of the sealed portion.

[0078] On the other hand, the sealant layer 30 according to the present invention may have a composite film structure in which two or more materials are each formed in layers. For example, the sealant layer 30 may have a multilayer structure. Between each layer of the sealant layer 30 having a composite film structure, an adhesive layer and / or a skin layer may be arranged. The adhesive layer and / or skin layer has thermal adhesion properties and plays a role in supporting the adhesion between each layer of the sealant layer 30. For example, the adhesive layer and / or skin layer may contain, but is not limited to, a polypropylene resin. Furthermore, the adhesive layer and / or skin layer may be arranged between the sealant layer 30 and the gas barrier layer 20.

[0079] The pouch film laminate of the present invention described above can be manufactured by methods for manufacturing pouch film laminates known in the art. For example, the pouch film laminate of the present invention can be manufactured by attaching a base layer 10 to the upper surface of a gas barrier layer 20 using an adhesive, and forming a sealant layer 30 on the lower surface of the gas barrier layer 20 using co-extrusion or an adhesive layer, or by methods such as dry lamination or sandwich lamination. However, the method for manufacturing the pouch film laminate is not limited to these.

[0080] The pouch film laminate according to the present invention may have a total thickness of 120 μm to 300 μm, specifically 130 μm to 280 μm, and more preferably 140 μm to 250 μm. When the thickness of the pouch film laminate satisfies the above range, it is possible to minimize the reduction in battery housing space and the decrease in sealing durability due to an increase in the thickness of the pouch laminate, while also increasing the molding depth.

[0081] Pouch-type rechargeable battery Next, the pouch-type secondary battery according to the present invention will be described.

[0082] Figure 2 is an exploded assembly diagram of the pouch-type secondary battery 200 according to the present invention.

[0083] As shown in Figure 2, the pouch-type secondary battery 200 according to the present invention may include a pouch-type battery case 210 manufactured by molding the aforementioned pouch film laminate, and an electrode assembly 260 housed in the pouch-type battery case 210. Specifically, the pouch-type secondary battery 200 according to the present invention may include a pouch-type battery case 210, an electrode assembly 260, electrode leads 280, an insulating part 290, and an electrolyte (not shown).

[0084] The components of the pouch-type secondary battery of the present invention will be described in more detail below with reference to Figure 2.

[0085] (Pouch-type battery case) The pouch-type battery case 210 can be manufactured by molding the pouch film laminate of the present invention described above. The pouch-type battery case 210 can house the electrode assembly 260 inside. The detailed structure and physical properties of the pouch film laminate are as described above, so a detailed explanation will be omitted.

[0086] The pouch film laminate may be drawn and stretched using a punch or the like for the manufacture of the pouch-type battery case 210. As a result, the pouch-type battery case 210 may include a cup portion 222 and a housing portion 224. The housing portion 224 is a portion for housing an electrode assembly and can mean a housing space that is formed in a pocket shape inside the cup portion 222 when the cup portion 222 is formed.

[0087] According to one embodiment of the present invention, the pouch-type battery case 210 may include a first case 220 and a second case 230, as shown in Figure 2. The first case 220 includes a housing section 224 capable of housing an electrode assembly 260, and the second case 230 may cover the housing section 224 from above to prevent the electrode assembly 260 from detaching from the battery case 210. The first case 220 and the second case 230 may be manufactured with one side connected to the other, as shown in Figure 2, but are not limited to this, and can be manufactured in various ways, such as being manufactured separately from each other.

[0088] According to another embodiment of the present invention, when forming cup portions in a pouch film laminate, drawing-molding may be performed so that two symmetrical cup portions 222 and 232 are adjacent to each other in one pouch film laminate. In that case, cup portions 222 and 232 can be formed in the first case 220 and the second case 230, respectively, as shown in Figure 2. The electrode assembly 260 is housed in the housing portion 224 provided in the cup portion 222 of the first case 220, and then the bridge portion 240 formed between the two cup portions 222 and 232 is folded so that the two cup portions 222 and 232 face each other. In that case, the cup portion 232 of the second case 230 can house the electrode assembly 260 from above. Thus, since two cup portions 222 and 232 house one electrode assembly 260, a thicker electrode assembly 260 can be housed than when there is only one cup portion 222. Furthermore, since one edge of the secondary battery 200 is formed when the pouch-type battery case 210 is folded, the number of edges to be sealed during the subsequent sealing process can be reduced. This improves the process speed of the pouch-type secondary battery 200 and reduces the number of sealing steps.

[0089] The pouch-type battery case 210 may be sealed with the electrode assembly 260 housed inside such that a portion of the electrode lead 280, i.e., the terminal portion, is exposed. Specifically, the electrode lead 280 is connected to the electrode tab 270 of the electrode assembly 260, and an insulating portion 290 is formed on a portion of the electrode lead 280. The electrode assembly 260 is then housed in a housing portion 224 provided in the cup portion 222 of the first case 220, and the housing portion 224 is covered from above by the second case 230. Next, an electrolyte is injected into the housing portion 224, and the sealing portions 250 formed on the edges of the first case 220 and the second case 230 are sealed.

[0090] The sealing portion 250 serves to seal the housing portion 224. Specifically, the sealing portion 250 may be formed along the edge of the housing portion 224 to seal the housing portion 224. The sealing temperature of the sealing portion 250 may be 180°C to 250°C, specifically 200°C to 250°C, and more specifically 210°C to 240°C. When the sealing temperature meets the above numerical range, the pouch-type battery case 210 can achieve sufficient sealing strength through heat bonding.

[0091] (electrode assembly) The electrode assembly 260 may be inserted into the pouch-type battery case 210, injected with the electrolyte, and then sealed by the pouch-type battery case 210.

[0092] The electrode assembly 260 may be formed by sequentially stacking a positive electrode, a separator membrane, and a negative electrode. Specifically, the electrode assembly 260 may include two types of electrodes, a positive electrode and a negative electrode, and a separator membrane interposed between the electrodes to insulate them from each other.

[0093] The positive and negative electrodes may each have a structure in which an active material slurry is coated onto a metal foil or metal mesh electrode current collector containing aluminum and copper, respectively. The slurry may typically be formed by stirring granular active material, auxiliary conductors, binders, conductive materials, etc., with a solvent added. The solvent may be removed in a subsequent step.

[0094] A slurry of electrode active material and binder and / or conductive material can be applied to a positive electrode current collector and a negative electrode current collector to produce the positive and negative electrodes, and the electrode assembly 260 can be manufactured in a predetermined shape by stacking them on both sides of a separator. The types of electrode assemblies 260 include, but are not limited to, stack type, jelly roll type, and stack-and-fold type.

[0095] The electrode assembly 260 may include an electrode tab 270.

[0096] The electrode tabs 270 are connected to the positive and negative electrodes of the electrode assembly 260, respectively, and protrude outward from the electrode assembly 260, serving as pathways for electron movement between the inside and outside of the electrode assembly 260. The electrode current collector included in the electrode assembly 260 may consist of a portion coated with electrode active material and an end portion not coated with electrode active material, i.e., a plain portion. The electrode tabs 270 may be formed by cutting the plain portion, or by connecting another conductive member to the plain portion by ultrasonic welding or the like. As shown in Figure 2, the electrode tabs 270 may protrude in different directions from the electrode assembly 260, but are not limited to this, and can be formed to protrude in various directions, such as protruding parallel to the same direction from one side.

[0097] (Electrode leads) The electrode leads 280 can supply electricity to the outside of the secondary battery 200. The electrode leads 280 may be connected to the electrode tabs 270 of the electrode assembly 260 by spot welding or the like.

[0098] The electrode lead 280 may be connected to the electrode assembly 260 and protrude outside the pouch-type battery case 210 via the seal portion 250. Specifically, one end of the electrode lead 280 may be connected to the electrode assembly 260, specifically to the electrode tab 270, and the other end of the electrode lead 280 may protrude outside the pouch-type battery case 210.

[0099] The electrode leads 280 may include a positive electrode lead 282, one end of which is connected to the positive electrode tab 272 and extends in the direction in which the positive electrode tab 272 protrudes, and a negative electrode lead 284, one end of which is connected to the negative electrode tab 271 and extends in the direction in which the negative electrode tab 271 protrudes. The other ends of both the positive electrode lead 282 and the negative electrode lead 284 may protrude outside the battery case 210. Thus, electricity generated inside the electrode assembly 260 can be supplied to the outside. Also, since the positive electrode tab 272 and the negative electrode tab 271 are formed to protrude in various directions, the positive electrode lead 282 and the negative electrode lead 284 can also extend in various directions. The positive electrode lead 282 and the negative electrode lead 284 may be made of different materials. That is, the positive electrode lead 282 may be made of the same aluminum (Al) material as the positive electrode current collector, and the negative electrode lead 284 may be made of the same copper (Cu) material as the negative electrode current collector or copper material coated with nickel (Ni). A portion of the electrode lead 280 protruding from the outside of the battery case 210 may serve as a terminal and be electrically connected to an external terminal.

[0100] (Insulation part) The insulating portion 290 prevents electricity generated from the electrode assembly 260 from flowing through the electrode leads 280 to the battery case 210, thereby maintaining the seal of the battery case 210. For this purpose, the insulating portion 290 may be formed of a non-conductive material that does not easily conduct electricity. Generally, insulating tape or film that is easy to attach to the electrode leads 280 and is relatively thin is often used as the insulating portion 290, but it is not limited to these, and any material that can insulate the electrode leads 280 may be used.

[0101] The insulating portion 290 may be positioned to surround the outer circumferential surface of the electrode lead 280. Specifically, at least a portion of the electrode lead 280 may be surrounded by the insulating portion 290. In that case, the insulating portion 290 may be positioned between the electrode lead 280 and the pouch-type battery case 210. The insulating portion 290 is positioned within the seal portion 250 where the first case 220 and the second case 230 of the pouch-type battery case 210 are heat-fused together, allowing the electrode lead 280 to be bonded to the battery case 210.

[0102] (electrolyte) The pouch-type secondary battery 200 according to the present invention may further include an electrolyte (not shown) that is injected into the inside of the pouch-type battery case 210. The electrolyte is for moving lithium ions generated by the electrochemical reaction of electrodes during charging / discharging of the secondary battery 200, and may include a non-aqueous organic electrolyte which is a mixture of lithium salt and organic solvents, or a polymer using a polymer electrolyte. The electrolyte may also include a sulfide-based, oxide-based, or polymer-based solid electrolyte, and such a solid electrolyte may have flexibility that makes it easily deformable by external force. [Examples]

[0103] The present invention will be described in more detail below with reference to specific examples. However, the following examples are merely illustrative to aid in understanding the present invention and do not limit its scope. It will be obvious to those skilled in the art that various modifications and alterations are possible within the scope of the present invention and its technical concept, and that such modifications and alterations are included in the appended claims.

[0104] Examples and Comparative Examples Example 1: Manufacturing of a pouch film laminate A sealant layer was manufactured by adding polypropylene (PP) particles with a particle size of 10 μm to the surface of a polypropylene (PP) film measuring 400 mm in width, 50 m in length, and 80 μm in thickness, in order to create surface roughness.

[0105] Subsequently, a second adhesive film (16b), a 15 μm thick nylon film, a first adhesive film (16a), and a 12 μm thick polyethylene terephthalate (PET) film were sequentially laminated onto one side of a 40 μm thick aluminum alloy thin film, and the manufactured sealant layer was sequentially laminated onto the other side of the aluminum alloy thin film. As a result, a pouch film laminate was produced with a structure in which the manufactured sealant layer / aluminum alloy thin film / second adhesive film / nylon film / first adhesive film / polyethylene terephthalate film were sequentially laminated.

[0106] Example 2: Manufacturing of a pouch film laminate A pouch film laminate was manufactured in the same manner as in Example 1, except that a sealant layer was prepared by adding polypropylene (PP) particles having a particle size of 15 μm to the surface layer to form surface roughness.

[0107] Example 3: Manufacturing of a pouch film laminate A pouch film laminate was manufactured in the same manner as in Example 1, except that a sealant layer was prepared by adding polypropylene (PP) particles having a particle size of 20 μm to the surface layer to form surface roughness.

[0108] Example 4: Manufacturing of a pouch film laminate A pouch film laminate was manufactured in the same manner as in Example 1, except that a sealant layer was prepared by adding polypropylene (PP) particles having a particle size of 25 μm to the surface layer to form surface roughness.

[0109] Comparative Example 1: Manufacturing of a pouch film laminate A pouch film laminate was manufactured in the same manner as in Example 1, except that a sealant layer was prepared by adding Si particles having a particle size of 1 μm to the surface layer to form surface roughness.

[0110] Comparative Example 2: Manufacturing of a pouch film laminate A pouch film laminate was manufactured in the same manner as in Example 1, except that a sealant layer was prepared by adding Si particles having a particle size of 3 μm to the surface layer to form surface roughness.

[0111] Comparative Example 3: Manufacturing of a pouch film laminate A pouch film laminate was manufactured in the same manner as in Example 1, except that a sealant layer was prepared by adding Si particles having a particle size of 5 μm to the surface layer to form surface roughness.

[0112] Comparative Example 4: Manufacturing of a pouch film laminate A pouch film laminate was manufactured in the same manner as in Example 1, except that a sealant layer was prepared by adding Si particles having a particle size of 50 μm to the surface layer to form surface roughness.

[0113] Experimental Example 1: Measurement of Surface Roughness The surface roughness of the sealant layer within each pouch film laminate produced by Examples 1-4 and Comparative Examples 1-4 was measured using an optical measuring instrument (NV-2700 Optical Profiler, Nano System).

[0114] The measured surface roughness (Ra) is listed in [Table 1] below.

[0115] [Table 1]

[0116] Experimental Example 2: Measurement of the coefficient of friction according to temperature The pouch film laminates produced in Examples 1-4 and Comparative Examples 1-4 were stored at 25°C and 60°C for 6 hours, respectively, and then their coefficients of friction were measured.

[0117] As a method for measuring the coefficient of friction, a sled metal measuring 130 mm (MD direction) x 65 mm (TD direction) and weighing 200 g was brought into contact with the sealant layer of a pouch film laminate measuring 500 mm (MD direction) x 400 mm (TD direction) and measured.

[0118] In detail, the sled metal was moved 100 mm on the sealant layer at a speed of 100 mm / min, and the coefficient of friction was measured by taking the average of the coefficients of motion measured five times in the 20 mm to 80 mm section.

[0119] The coefficients of friction measured for pouch film laminates stored at 25°C and 60°C for 6 hours each are shown in [Table 2] below.

[0120] [Table 2]

[0121] As shown in [Table 2] above, Comparative Examples 1-4, in which the surface roughness of the sealant layer was formed to be either excessively low or excessively high, had a higher ratio of the coefficient of friction at 60°C to the coefficient of friction at 25°C than Examples 1-4.

[0122] Experimental Example 3: Evaluation of the moldability of pouch film laminates according to temperature The pouch film laminates produced in Examples 1-4 and Comparative Examples 1-4 were stored at 25°C and 60°C for 6 hours, respectively, and then their moldability was evaluated.

[0123] As a method for evaluating the moldability of the pouch film laminate, each pouch film laminate was cut to the same size of 300 mm (MD direction) x 400 mm (TD direction), and then the molding depth at which cracks occurred was recorded while varying the molding depth in a battery case molding apparatus having two molding sections of size 90 mm (MD direction) x 160 mm (TD direction). Here, the punch and molding section of the battery case molding apparatus have filleted corners and edges, with the punch having a curvature of 2 mm at the corners and 0.5 mm at the edges, and the molding section having a curvature of 2.0 mm at the corners and 1 mm at the edges. The clearance between the punch and the molding section is 0.5 mm.

[0124] The molding depths measured for pouch film laminates stored at 25°C and 60°C for 6 hours each are shown in [Table 3] below.

[0125] [Table 3]

[0126] As shown in [Table 3] above, in Examples 1 to 4, unlike Comparative Examples 1 to 4, there was no significant change in the molding depth of the cup portion depending on the temperature, and it can be seen that even when using a pouch film laminate that had been stored at high temperatures, it showed excellent molding depth. [Explanation of Symbols]

[0127] 1. Laminated pouch film 10 Base material layer 20 Gas barrier layer 30 sealant layer 200 pouch-type rechargeable batteries 210 Pouch-type Battery Cases 220 Case 1 222 Cup section 224 Storage Unit 230 Case 2 232 Cup section 240 Bridge section 250 seal section 260 Electrode Assembly 270 electrode tabs 272 Positive Tab 271 Negative electrode tab 280 electrode leads 282 Positive lead 284 Negative lead 290 Insulation part

Claims

1. It includes sequentially stacked substrate layers, a gas barrier layer, and a sealant layer. The sealant layer is represented by the following [Equation 1] f Ｔ The value is between 0.32 and 3.

1. The surface roughness (Ra) of the sealant layer is 0.11 μm to 0.75 μm. [Formula 1] f Ｔ =f Ｔ２ / f Ｔ１ In the above [Equation 1], f Ｔ１ This is the coefficient of friction of the sealant layer at T1, and f Ｔ２ The coefficient of friction of the sealant layer at T2, where T1 and T2 are different temperatures, is a pouch film laminate.

2. Said f Ｔ The pouch film laminate according to claim 1, wherein the value of is 0.33 to 3.

0.

3. The pouch film laminate according to claim 1, wherein T1 is 25°C and T2 is any one temperature between 0°C and 125°C, excluding 25°C.

4. The pouch film laminate according to claim 1, wherein T1 is 25°C and T2 is 60°C.

5. The pouch film laminate according to claim 1, wherein the surface roughness (Ra) of the sealant layer is 0.16 μm to 0.55 μm.

6. The pouch film laminate according to claim 1, wherein the sealant layer includes embossed protrusions.

7. The pouch film laminate according to claim 1, wherein the coefficient of friction of the sealant layer at 60°C is 0.38 or less.

8. The aforementioned pouch film laminate is represented by D [Formula 2] below. Ｔ The value is between 0.82 and 1.

22. [Formula 2] D Ｔ =D Ｔ２，ａ / D Ｔ１，ａ In the above [Equation 2], D Ｔ１，ａ This is the molding depth at which cracks occur when the pouch film laminate is cut to a size of 300 mm x 400 mm at T1,a and then molded to have two cup sections measuring 90 mm wide x 160 mm long, and D Ｔ２，ａ The pouch film laminate according to claim 1, wherein T1,a and T2,a are different temperatures, and a crack occurs when the pouch film laminate is cut to a size of 300 mm x 400 mm at T2,a and then molded to have two cup portions measuring 90 mm wide x 160 mm long.

9. The pouch film laminate according to claim 1, wherein the base material layer has a laminated structure of polyethylene terephthalate film and nylon film.

10. The pouch film laminate according to claim 1, wherein the thickness of the gas barrier layer is 20 μm to 100 μm.

11. The pouch film laminate according to claim 1, wherein the thickness of the sealant layer is 30 μm to 130 μm.

12. A pouch-type battery case manufactured by drawing-molding the pouch film laminate described in claim 1.

13. A pouch-type rechargeable battery comprising the pouch-type battery case described in claim 12.

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