Pouch exterior material for secondary battery, and secondary battery

Abstract

The present invention relates to a pouch exterior material, and to a pouch exterior material and a secondary battery comprising same, a polymer material, pushed out from a sealed portion at a tab portion, being uniformly formed even at an unsealed portion, thereby preventing a reduction in the thickness of a sealant layer when the pouch exterior material and a lead tab film are sealed, and thus insulation defects are prevented and long-term reliability such as that of chemical resistance can be improved.

Description

Pouch outer material for secondary batteries and secondary batteries

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0189928, filed December 22, 2023, the entire contents of which are incorporated herein by reference.

[0003]

[0004] Technology field

[0005] The present invention relates to a pouch outer material for a secondary battery and a secondary battery including the same.

[0006]

[0007] Recently, as the application areas of secondary batteries have rapidly expanded to include not only power supply for electronic devices such as electric, electronic, communication, and computer devices, but also power storage for large-area devices such as automobiles and power storage devices, the demand for high-capacity, high-output, and high-stability lithium secondary batteries is increasing.

[0008] Lithium secondary batteries are generally manufactured by applying a positive electrode active material capable of inserting and de-inserting lithium ions or a negative electrode active material capable of absorbing and releasing lithium ions, and optionally a material mixed with a binder and a conductive material, to a positive electrode current collector and a negative electrode current collector, respectively, to manufacture the negative electrode and the positive electrode, laminating these on both sides of a separator to form an electrode assembly of a predetermined shape, and then inserting this electrode assembly and a non-aqueous electrolyte into a battery case.

[0009] Lithium secondary batteries can be divided into cylindrical secondary batteries, square secondary batteries, and pouch-type secondary batteries depending on their structure. Among these, pouch-type secondary batteries are manufactured by accommodating the electrode assembly within a pouch-type sheet and then sealing the sheet. Compared to other types of secondary batteries, they have a simple structure and a large capacity per unit volume, so they are widely used in automobile batteries and energy storage devices.

[0010] The case of these pouch-type secondary batteries is a pouch-shaped sheet that protects the electrodes and electrolyte from the outside, and is composed of a metal film and a polymer material for sealing. The polymer material used for the sealant layer is a thermoplastic, heat-sealing material composed of an olefin-based material such as polypropylene or polyethylene.

[0011] When using the case of the above pouch-type secondary battery, in order to maintain electrical connection from the electrode assembly housed inside the case to the outside of the case, the tab needs to be extended outside the case. Accordingly, when sealing the case of the above pouch-type secondary battery, the lead tab film and the pouch-type sheet are directly sealed at the tab area.

[0012] However, as shown in Fig. 1, unlike other sealing areas, in an area directly sealed to the lead tab film, there is a problem in that the polymer material of the sealant layer is pushed between the sealing area (sealing area) formed on the lead tab film after sealing and the unsealed area (unsealed area) in the direction of the storage area of ​​the electrode assembly of the case of the pouch-type secondary battery (occurrence area).

[0013] Specifically, when directly sealing a pouch-shaped sheet on a lead tab film at a tab portion, the phenomenon of the polymer material of the sealant layer being pushed from the sealed portion (sealed portion) to the unsealed portion (unsealed portion) can be confirmed from a cross-sectional image of the sealed portion for the tab portion, as shown in Fig. 2. When sealing the lead tab film and the pouch-shaped sheet at the tab portion, the sealed portion (sealed portion) is pressurized and heated by the sealing block, and at this time, the polymer material of the sealant layer is pushed from the sealed portion (sealed portion) formed on the lead tab film to the unsealed portion (unsealed portion). Accordingly, the thickness of the unsealed area (unsealed area) will inevitably increase due to the pushed out polymer material, and unlike the sealed area (sealed area), the pressurization and heating by the sealing block in the unsealed area (unsealed area) are not evenly transferred to the ambient pressure and ambient heat, so the sealant layer cannot be evenly fused onto the lead tab film. Therefore, as shown in Fig. 2, the polymer material pushed out from the sealed area (sealed area) at the tab area flows unevenly in the unsealed area (unsealed area), cools, clumps, and lifts, and as a result, an area where the sealant layer is thinner than the original thickness occurs. If an area where the sealant layer is thinner occurs in this way, long-term reliability issues such as poor insulation and reduced chemical resistance may occur in that area.

[0014]

[0015] The problem to be solved by the present invention is that, when a secondary battery is accommodated using a pouch outer case including a pouch film laminate, when the pouch outer case and the lead tab film are sealed, a polymer material that is pushed out from the sealed area at the tab area is uniformly formed even in an unsealed area, thereby preventing the thickness of the sealant layer from becoming thinner, thereby preventing insulation failure and improving long-term reliability such as chemical resistance.

[0016] That is, the present invention is a film laminate of a pouch outer case for accommodating a secondary battery, and the purpose of the present invention is to provide a pouch film laminate in which, when the pouch outer case and the lead tab film are sealed, a polymer material pushed out from the sealed area at the tab area is uniformly formed even in an unsealed area.

[0017] In addition, the present invention aims to provide a pouch outer material including the above pouch film laminate.

[0018] In addition, the present invention aims to provide a secondary battery including the pouch outer material.

[0019]

[0020] To solve the above problem, the present invention provides a pouch outer material for a secondary battery and a secondary battery including the same.

[0021] (1) The present invention provides a pouch outer case including a pouch film laminate including an outer layer, a barrier layer, and an inner layer, wherein a peel strength of a lead tab film seal formed by contacting at least one side of a lead tab film with the inner layer and then sealing it is 130 N / 15 mm or more, and when a cross-section of the pouch outer case is checked in a direction perpendicular to the lead tab film seal, in a region where the thickness of the inner layer increases adjacent to the lead tab film seal, there is no region where the thickness of the inner layer is thinner than the average thickness of the inner layer in the receiving space region.

[0022] (2) The present invention provides a pouch outer material in the above (1), wherein the inner layer includes at least one selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber.

[0023] (3) The present invention provides a pouch outer material having an average thickness of the inner layer of (1) or (2) above of 40 ㎛ or more and 120 ㎛ or less.

[0024] (4) The present invention provides a pouch outer material in any one of the above (1) to (3), wherein the inner layer includes a first sealant layer disposed on the barrier layer, and a second sealant layer disposed on the first sealant layer.

[0025] (5) The present invention provides a pouch outer material in the above (4), wherein the first sealant layer has a melting point of 130°C or higher and 150°C or lower.

[0026] (6) The present invention provides a pouch outer material in the above (4), wherein the first sealant layer has a melting point of more than 150°C and less than 180°C.

[0027] (7) The present invention provides a pouch outer material in any one of the above (4) to (6), wherein the first sealant layer has a melting index (230°C, load 2.16 kg) measured by the ASTM D1238 method of 16 g / 10 min or more and 30 g / 10 min or less.

[0028] (8) The present invention provides a pouch outer material in any one of the above (4) to (6), wherein the first sealant layer has a melting index (230°C, load 2.16 kg) measured by the ASTM D1238 method of 5 g / 10 min or more and less than 16 g / 10 min.

[0029] (9) The present invention provides a pouch outer material in any one of the above (4) to (6), wherein the first sealant layer has an average thickness of 10 µm or more and 50 µm or less.

[0030] (10) The present invention provides a pouch outer material in any one of the above (4) to (9), wherein the second sealant layer has a melting point of 120°C or higher and 160°C or lower.

[0031] (11) The present invention provides a pouch outer material in any one of the above (4) to (10), wherein the second sealant layer has a melting index (230°C, load 2.16 kg) measured by the ASTM D1238 method of 5 g / 10 min or more and 15 g / 10 min or less.

[0032] (12) The present invention provides a pouch outer material in any one of the above (4) to (11), wherein the second sealant layer has an average thickness of 30 ㎛ or more and 70 ㎛ or less.

[0033] (13) The present invention provides a pouch outer material having an average thickness of 170 ㎛ or more and 200 ㎛ or less, wherein the pouch film laminate is in any one of the above (1) to (12).

[0034] (14) The present invention provides a pouch outer material formed by sealing the lead tab film sealing portion with at least one surface of the lead tab film and the inner layer after contacting each other at a temperature of 205°C or higher, for 1.5 seconds or longer and 2.7 seconds or shorter, under a pressure of 0.1 MPa or higher and 0.5 MPa or lower, so that the thickness of the inner layer at the sealing portion is less than 85% of the thickness of the inner layer of the pouch film laminate, in any one of the above (1) to (13).

[0035] (15) The present invention provides a secondary battery including a pouch outer case according to any one of (1) to (14).

[0036]

[0037] The pouch outer material of the present invention can uniformly form a polymer material that is pushed out from the sealed portion at the tab portion when the pouch film laminate and the lead tab film are sealed, even in the unsealed portion, thereby preventing the thickness of the sealant layer of the pouch film laminate from becoming thin, thereby preventing insulation failure and improving long-term reliability such as chemical resistance.

[0038]

[0039] Figure 1 is an optical image showing a sealed portion (sealed portion) and an unsealed portion (unsealed portion) of a tab portion in a case of a pouch-type secondary battery.

[0040] Figure 2 is an optical image showing a cross-section of a sealed portion (sealed portion) and an unsealed portion (unsealed portion) of a tab portion in a case of a pouch-type secondary battery.

[0041] FIG. 3 is an optical image showing a sealed portion (sealed portion) and an unsealed portion (unsealed portion) of a tab portion of a pouch outer material manufactured according to Example 17 of the present invention.

[0042] FIG. 4 is an optical image showing a sealed portion (sealed portion) and an unsealed portion (unsealed portion) of a tab portion of a pouch outer material manufactured according to Example 18 of the present invention.

[0043]

[0044] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0045] The terms or words used in the description and claims of the present invention should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0046]

[0047] The present invention provides a pouch outer material including a pouch film laminate.

[0048] According to one embodiment of the present invention, the pouch outer case includes a pouch film laminate including an outer layer, a barrier layer, and an inner layer, and a peel strength of a lead tab film sealing portion formed by contacting and sealing at least one surface of a lead tab film and the inner layer is 130 N / 15 mm or more, and when a cross-section of the pouch outer case is checked in a direction perpendicular to the lead tab film sealing portion, in a region where the thickness of the inner layer increases adjacent to the lead tab film sealing portion, there may be no region where the thickness of the inner layer is thinner than the average thickness of the inner layer in the receiving space region. The pouch outer case not only secures a sealing force by sufficient adhesive force between the pouch outer case and the lead tab film, but also prevents the thickness of the inner layer from becoming thin by uniformly forming a polymer material pushed out from the sealing portion at the tab portion even in an unsealed region, thereby preventing insulation failure and improving long-term reliability such as chemical resistance.

[0049] According to one embodiment of the present invention, the pouch outer case may include at least one of the upper film and the lower film constituting the pouch outer case, and preferably, both the upper film and the lower film constituting the pouch outer case may be the pouch film laminate.

[0050] According to one embodiment of the present invention, the pouch outer material can secure a sealing force for a sealing portion for sealing between the upper film and the lower film by applying the pouch film laminate as the upper film and / or the lower film, respectively, and can also secure a sealing force between the upper film and / or the lower film and the lead tab film.

[0051] According to one embodiment of the present invention, the pouch outer material may have a peel strength of 130 N / 15 mm or more of a lead tab film sealing portion formed by contacting at least one side of the lead tab film and the inner layer and then sealing it, and specific examples thereof include 130 N / 15 mm or more, 131 N / 15 mm or more, 132 N / 15 mm or more, 133 N / 15 mm or more, 134 N / 15 mm or more, 135 N / 15 mm or more, 136 N / 15 mm or more, 137 N / 15 mm or more, 138 N / 15 mm or more, 139 N / 15 mm or more, 140 N / 15 mm or more, 141 N / 15 mm or more, 142 N / 15 mm or more, 143 N / 15 mm or more, 144 N / 15 mm or more, 145 N / 15 mm or more, 146 N / 15 mm It may be 147 N / 15 mm or more, 148 N / 15 mm or more, 149 N / 15 mm or more, 150 N / 15 mm or more, 151 N / 15 mm or more, 152 N / 15 mm or more, 153 N / 15 mm or more, 154 N / 15 mm or more, 155 N / 15 mm or more, 156 N / 15 mm or more, 157 N / 15 mm or more, 158 N / 15 mm or more, 159 N / 15 mm or more, 160 N / 15 mm or more, 161 N / 15 mm or more, 162 N / 15 mm or more, 163 N / 15 mm or more, or 164 N / 15 mm or more. Since the higher the peel strength, the better, the upper limit thereof is not particularly limited, but may be 200 N / 15 mm or less, 190 N / 15 mm or less, 180 N / 15 mm or less, 179 N / 15 mm or less, 178 N / 15 mm or less, or 177 N / 15 mm or less, and excellent sealing power can be secured within this range.

[0052] According to one embodiment of the present invention, when the cross-section of the pouch exterior material is checked in a direction perpendicular to the lead tab film sealing portion, in a region where the thickness of the inner layer increases adjacent to the lead tab film sealing portion, there may be no region where the thickness of the inner layer is thinner than the average thickness of the inner layer in the receiving space region. Here, the cross-section of the pouch exterior material in the direction perpendicular to the lead tab film sealing portion may be checked with the naked eye, but may be checked using an optical image for more accurate thickness measurement. Here, any optical device for capturing the optical image may be used without limitation as long as it is an optical device capable of capturing at a magnification that can confirm the change in the thickness of the inner layer. The region where the thickness of the inner layer increases adjacent to the lead tab film sealing portion refers to a region where, when at least one surface of the lead tab film is brought into contact with the inner layer and then sealed, the inner layer located at the sealing portion is pushed out toward the periphery of the sealing portion by pressure during sealing, thereby increasing the thickness of the inner layer. Here, the area where the thickness of the inner layer increases varies depending on the pouch outer packaging material, so the area cannot be limited to an exact ratio. However, it refers to the area starting from the sealing portion based on the average thickness of the inner layer, increasing in the direction of the accommodation space of the pouch outer packaging material, and then immediately before the area where the average thickness of the inner layer begins to decrease to recover the average thickness again. The area where the thickness of the inner layer increases may appear as a shape where the shape increases evenly, or may appear in various shapes such as a shape with a rough structure, a shape with an embossed pattern, a bumpy shape, a convex shape, etc. However, regardless of the shape, if there is an area where the thickness of the inner layer is lower than the average thickness of the inner layer in the accommodation space area, this may appear as a dented shape, a shape with a peak point, etc., and in such an area, long-term reliability may be problematic, such as poor insulation and reduced chemical resistance.Accordingly, the above-described pouch outer material can solve the above problem by ensuring that, in a region where the thickness of the inner layer increases adjacent to the lead tab film sealing portion, there is no region where the thickness of the inner layer is thinner than the average thickness of the inner layer in the receiving space region. Meanwhile, the average thickness of the inner layer in the receiving space region may represent the average thickness of the inner layer of the pouch film laminate, and specifically, may mean the average thickness of the inner layer in the pouch film laminate itself without any sealing force being applied.

[0053] According to one embodiment of the present invention, the outer layer is a layer located on the outer surface of the pouch outer material, and may include at least one selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber.

[0054] According to one embodiment of the present invention, the outer layer may be composed of a laminate of two or more layers in terms of diversifying functions. As a specific example, the outer layer may include a surface protection layer and a stretching auxiliary layer. Here, the surface protection layer may be a layer constituting the outermost outer layer of the pouch film laminate, and may be a layer that primarily protects the pouch outer material from the external environment, and the stretching auxiliary layer may be a layer that assists in the adhesion of the surface protection layer and the barrier layer, and at the same time prevents the surface protection layer and the barrier layer from being separated from each other when being stretched.

[0055] According to one embodiment of the present invention, the surface protection layer may include at least one selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber. The components of the surface protection layer may be selected and used within a range of mechanical properties that do not impair durability, heat resistance, pinhole resistance, chemical resistance, and electrical insulation, which are functions of the surface protection layer of the pouch outer material. As a specific example, the surface protection layer may include polyethylene terephthalate, which has excellent durability, heat resistance, pinhole resistance, chemical resistance, and electrical insulation, and as a more specific example, it may be a membrane or film made of polyethylene terephthalate.

[0056] According to one embodiment of the present invention, the stretching auxiliary layer may include at least one selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber. The components of the stretching auxiliary layer may be selected and used within a range of mechanical properties that do not impair the function of the stretching auxiliary layer of the pouch outer cover. As a specific example, the stretching auxiliary layer may include nylon that is easily adhered to the surface protection layer and has similar behavior when stretched to the barrier layer, and as a more specific example, it may be a membrane or film made of nylon.

[0057] According to one embodiment of the present invention, the surface protective layer may have an average thickness of 10 μm or more and 20 μm or less. As a specific example, the surface protective layer may have an average thickness of 10 μm or more, 11 μm or more, or 12 μm or more, and may also have an average thickness of 20 μm or less, 19 μm or less, 18 μm or less, 17 μm or less, 16 μm or less, 15 μm or less, 14 μm or less, 13 μm or less, or 12 μm or less, and within this range, the surface protective effect can be secured while preventing the thickness of the secondary battery from becoming excessively thick due to the outer material.

[0058] According to one embodiment of the present invention, the stretching auxiliary layer may have an average thickness of 15 μm or more and 30 μm or less. As a specific example, the surface protection layer may have an average thickness of 15 μm or more, 16 μm or more, 17 μm or more, 18 μm or more, 19 μm or more, 20 μm or more, 21 μm or more, 22 μm or more, 23 μm or more, 24 μm or more, or 25 μm or more, and may also have an average thickness of 30 μm or less, 29 μm or less, 28 μm or less, 27 μm or less, 26 μm or less, or 25 μm or less, and within this range, when stretched with the barrier layer, the adhesive strength between the surface protection layer and the barrier layer can be further improved while ensuring a behavior similar to that of the barrier layer.

[0059] According to one embodiment of the present invention, the barrier layer is a layer located at the center of the pouch outer case, and may be a layer that secures the mechanical strength of the pouch outer case, and at the same time prevents the ingress and egress of gas, moisture, etc. into and out of the secondary battery, and in particular, may be a layer that prevents leakage of electrolyte in a secondary battery using a non-aqueous electrolyte. In order to perform the above-described function, the barrier layer may be a foil made of metal, and as a specific example, may include at least one selected from the group consisting of aluminum, iron, copper, and nickel.

[0060] According to one embodiment of the present invention, the barrier layer may include aluminum, and as a more specific example, may be aluminum foil, from the viewpoint of ensuring mechanical strength suitable for a pouch outer material, preventing weight increase due to the pouch outer material, having excellent formability, and sufficiently securing the role of a barrier layer.

[0061] According to one embodiment of the present invention, the barrier layer may have an average thickness of 40 μm or more and 90 μm or less. As a specific example, the barrier layer may have an average thickness of 40 ㎛ or more, 41 ㎛ or more, 42 ㎛ or more, 43 ㎛ or more, 44 ㎛ or more, 45 ㎛ or more, 46 ㎛ or more, 47 ㎛ or more, 48 ㎛ or more, 49 ㎛ or more, 50 ㎛ or more, 51 ㎛ or more, 52 ㎛ or more, 53 ㎛ or more, 54 ㎛ or more, 55 ㎛ or more, 56 ㎛ or more, 57 ㎛ or more, 58 ㎛ or more, 59 ㎛ or more, or 60 ㎛ or more, and also 90 ㎛ or less, 89 ㎛ or less, 88 ㎛ or less, 87 ㎛ or less, 86 ㎛ or less, 85 ㎛ or less, 84 ㎛ or less, 83 ㎛ or less, 82 ㎛ or less, 81 ㎛ or less, 80 ㎛ or less, 79 ㎛ or less, 78 ㎛ or less, 77 ㎛ or less, 76 ㎛ or less, 75 ㎛ or less, 74 ㎛ or less, 73 ㎛ or less, 72 ㎛ or less, 71 ㎛ or less, 70 ㎛ or less, 69 ㎛ or less, 68 ㎛ or less, 67 ㎛ or less, 66 ㎛ or less, 65 ㎛ or less, 64 ㎛ or less, 63 ㎛ or less, 62 ㎛ or less, 61 ㎛ or less, or 60 ㎛ or less. When the barrier layer has an average thickness within the above range, the mechanical strength as a barrier layer can be secured while further improving the formability, and the thickness of the secondary battery can be prevented from being excessively thickened and the weight from increasing due to the outer material.

[0062] According to one embodiment of the present invention, the inner layer is a layer located on the inner surface of the pouch outer material, and may also be expressed as a sealant layer. The inner layer forms a sealing portion formed between the pouch film laminates and between the lead tab film and the pouch film laminate, and is a layer that directly contacts the secondary battery accommodated inside the pouch outer material, and therefore requires both heat sealability and formability, as well as electrolyte resistance and insulation resistance.

[0063] According to one embodiment of the present invention, the inner layer may include at least one selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber.

[0064] According to one embodiment of the present invention, the inner layer may be composed of a laminate of two or more layers in terms of diversifying functions. As a specific example, the inner 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 that assists in adhesion between the barrier layer and the second sealant layer, while further enhancing the function as an inner layer, and the second sealant layer may be a layer that constitutes the innermost inner layer of the pouch film laminate, and may be a layer that simultaneously seals and prevents leakage of a secondary battery, particularly a non-aqueous electrolyte.

[0065] According to one embodiment of the present invention, the first sealant layer may include at least one selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber. As a specific example, the first sealant layer may be polypropylene from the viewpoint of satisfying the peel strength for the sealing portion between the pouch film laminate and the lead tab film, and at the same time, maintaining the polymer material pushed out from the sealing portion at the tab portion so that it is uniformly formed even in the unsealed portion. As a more specific example, the first sealant layer may be a membrane or film made of polypropylene.

[0066] According to one embodiment of the present invention, the first sealant layer may have a melting point of 130° C. or higher and 150° C. or lower. As a specific example, the melting point of the first sealant layer may be 130° C. or higher, 131° C. or higher, 132° C. or higher, 133° C. or higher, 134° C. or higher, 135° C. or higher, 136° C. or higher, 137° C. or higher, 138° C. or higher, 139° C. or higher, or 140° C. or higher, and further, 150° C. or lower, 149° C. or lower, 148° C. or lower, 147° C. or lower, 146° C. or lower, or 145° C. or lower. When the melting point of the first sealant layer is controlled within the above range, not only is a sealing force secured through sufficient adhesive force between the pouch outer material and the lead tab film, but also the polymer material pushed out from the sealed portion at the tab portion is uniformly formed even in the unsealed portion, thereby preventing the thickness of the inner layer from becoming thinner, thereby preventing insulation failure and further improving long-term reliability such as chemical resistance.

[0067] According to one embodiment of the present invention, the first sealant layer may have a melting point of more than 150°C and less than or equal to 180°C. As a specific example, the first sealant layer may have a melting point of more than 150°C, more than 151°C, more than 152°C, more than 153°C, more than 154°C, more than 155°C, more than 156°C, more than 157°C, or more than 158°C, and may also have a melting point of 180°C or less, 179°C or less, 178°C or less, 177°C or less, 176°C or less, 175°C or less, 174°C or less, 173°C or less, 172°C or less, 171°C or less, 170°C or less, 169°C or less, 168°C or less, 167°C or less, 166°C or less, 165°C or less, 164°C or less, or 163°C or less.

[0068] According to one embodiment of the present invention, the first sealant layer may have a melt index (230° C., load 2.16 kg) measured by the ASTM D1238 method of 16 g / 10 min or more and 30 g / 10 min or less. As a specific example, the melt index (230° C., load 2.16 kg) of the first sealant layer measured by the ASTM D1238 method may be 16 g / 10 min or more, 17 g / 10 min or more, 18 g / 10 min or more, 19 g / 10 min or more, 20 g / 10 min or more, or 21 g / 10 min or more, and may also be 30 g / 10 min or less, 29 g / 10 min or less, 28 g / 10 min or less, 27 g / 10 min or less, 26 g / 10 min or less, 25 g / 10 min or less, or 24 g / 10 min or less. When the melting point and melting index of the first sealant layer are adjusted within the above range, the polymer material pushed out from the sealed portion at the tab portion is uniformly formed even in the unsealed portion, thereby preventing the thickness of the inner layer from becoming thinner, thereby preventing insulation failure and further improving long-term reliability such as chemical resistance.

[0069] According to one embodiment of the present invention, the first sealant layer may have a melt index (230° C., load 2.16 kg) measured by the ASTM D1238 method of 5 g / 10 min or more and less than 16 g / 10 min. As a specific example, the melt index (230° C., load 2.16 kg) of the first sealant layer measured by the ASTM D1238 method may be 5 g / 10 min or more, 6 g / 10 min or more, 7 g / 10 min or more, 8 g / 10 min or more, or 9 g / 10 min or more, and may also be less than 16 g / 10 min, 15 g / 10 min or less, 14 g / 10 min or less, 143 g / 10 min or less, 12 g / 10 min or less, or 11 g / 10 min or less.

[0070] According to one embodiment of the present invention, the first sealant layer may have an average thickness of 10 μm or more and 50 μm or less. As a specific example, the first sealant layer may have an average thickness of 10 µm or more, 11 µm or more, 12 µm or more, 13 µm or more, 14 µm or more, 15 µm or more, 16 µm or more, 17 µm or more, 18 µm or more, 19 µm or more, 20 µm or more, 21 µm or more, 22 µm or more, 23 µm or more, 24 µm or more, 25 µm or more, 26 µm or more, 27 µm or more, 28 µm or more, 29 µm or more, or 30 µm or more, and further, 50 µm or less, 49 µm or less, 48 ​​µm or less, 47 µm or less, 46 µm or less, 45 µm or less, 44 µm or less, 43 µm or less, 42 µm or less, 41 µm or less, 40 µm or less, It may be 39 ㎛ or less, 38 ㎛ or less, 37 ㎛ or less, 36 ㎛ or less, 35 ㎛ or less, 34 ㎛ or less, 33 ㎛ or less, 32 ㎛ or less, 31 ㎛ or less, or 30 ㎛ or less, and within this range, the sealing force can be further improved by sufficient adhesive force between the pouch outer material and the lead tab film.

[0071] According to one embodiment of the present invention, the second sealant layer may include at least one selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber. As a specific example, the second sealant layer may be polypropylene from the viewpoint of satisfying the peel strength for the sealing portion between the pouch film laminate and the lead tab film, and at the same time, maintaining the polymer material pushed out from the sealing portion at the tab portion so that it is uniformly formed even in the unsealed portion, and as a more specific example, may be a membrane or film made of non-stretched polypropylene.

[0072] According to one embodiment of the present invention, the second sealant layer may have a melting point of 120°C or higher and 160°C or lower. As a specific example, the melting point of the second sealant layer may be 120°C or higher, 121°C or higher, 122°C or higher, 123°C or higher, 124°C or higher, 125°C or higher, 126°C or higher, 127°C or higher, 128°C or higher, 129°C or higher, 130°C or higher, 131°C or higher, 132°C or higher, 133°C or higher, 134°C or higher, 135°C or higher, or 136°C or higher, and further, 160°C or lower, 159°C or lower, 158°C or lower, 157°C or lower, 156°C or lower, 155°C or lower, 154°C or lower, 153°C or lower, 152°C or lower, 151°C or lower, 150°C or lower. It may be 149 ℃ or less, 148 ℃ or less, 147 ℃ or less, 146 ℃ or less, 145 ℃ or less, 144 ℃ or less, 143 ℃ or less, 142 ℃ or less, 141 ℃ or less, or 140 ℃ or less. When the melting point of the second sealant layer is adjusted within the above range, not only is a sealing force secured by sufficient adhesive force between the pouch outer material and the lead tab film, but also the polymer material pushed out from the sealed area at the tab area is uniformly formed in the unsealed area, thereby preventing the thickness of the inner layer from becoming thinner, thereby preventing insulation failure and further improving long-term reliability such as chemical resistance.

[0073] According to one embodiment of the present invention, the melt index (230° C., load 2.16 kg) of the second sealant layer measured by the ASTM D1238 method may be 5 g / 10 min or more and 15 g / 10 min or less. As a specific example, the melt index (230° C., load 2.16 kg) of the second sealant layer measured by the ASTM D1238 method may be 5 g / 10 min or more, 6 g / 10 min or more, 7 g / 10 min or more, 8 g / 10 min or more, or 9 g / 10 min or more, and may also be 15 g / 10 min or less, 14 g / 10 min or less, 13 g / 10 min or less, or 12 g / 10 min or less. When the melting point and melting index of the second sealant layer are adjusted within the above range, the polymer material pushed out from the sealed portion at the tab portion is uniformly formed even in the unsealed portion, thereby preventing the thickness of the inner layer from becoming thinner, thereby preventing insulation failure and further improving long-term reliability such as chemical resistance.

[0074] According to one embodiment of the present invention, the second sealant layer may have an average thickness of 30 μm or more and 70 μm or less. As a specific example, the second sealant layer may have an average thickness of 30 ㎛ or more, 31 ㎛ or more, 32 ㎛ or more, 33 ㎛ or more, 34 ㎛ or more, 35 ㎛ or more, 36 ㎛ or more, 37 ㎛ or more, 38 ㎛ or more, 39 ㎛ or more, 40 ㎛ or more, 41 ㎛ or more, 42 ㎛ or more, 43 ㎛ or more, 44 ㎛ or more, 45 ㎛ or more, 46 ㎛ or more, 47 ㎛ or more, 48 ㎛ or more, 49 ㎛ or more, or 50 ㎛ or more, and further, 70 ㎛ or less, 69 ㎛ or less, 68 ㎛ or less, 67 ㎛ or less, 66 ㎛ or less, 65 ㎛ or less, 64 ㎛ or less, 63 ㎛ or less, 62 ㎛ or less, 61 ㎛ or less, 60 ㎛ or less, It may be 59 ㎛ or less, 58 ㎛ or less, 57 ㎛ or less, 56 ㎛ or less, 55 ㎛ or less, 54 ㎛ or less, 53 ㎛ or less, 52 ㎛ or less, 51 ㎛ or less, or 50 ㎛ or less, and within this range, the sealing force can be further improved by sufficient adhesive force between the pouch outer material and the lead tab film.

[0075] According to one embodiment of the present invention, when the inner layer includes a first sealant layer disposed on the barrier layer, and a second sealant layer disposed on the first sealant layer, the barrier layer and the inner layer may be formed by extruding a first sealant layer onto the barrier layer, and laminating a second sealant layer onto the first sealant layer. That is, the first sealant layer may be a sealant layer formed by extrusion onto the barrier layer, and the second sealant layer may be a sealant layer formed by laminating onto the first sealant layer. As a specific example, the first sealant layer disposed on the barrier layer, and the second sealant layer disposed on the first sealant layer may be formed by an extrusion lamination method in which the first sealant layer is extruded and laminated between the barrier layer and the second sealant layer. As another specific example, when the inner layer includes a first sealant layer disposed on the barrier layer and a second sealant layer disposed on the first sealant layer, the barrier layer and the inner layer can be formed by a co-extrusion method such that the first sealant layer and the second sealant layer are sequentially laminated on the barrier layer.

[0076] According to one embodiment of the present invention, the pouch outer material comprises an outer layer, a barrier layer and an inner layer, from the viewpoint of satisfying the peel strength of the sealed portion when at least one surface of the lead tab film and the inner layer are brought into contact and then sealed, and at the same time, forming a polymer material that is pushed out from the sealed portion at the tab portion uniformly in the unsealed portion, wherein the inner layer comprises a first sealant layer disposed on the barrier layer, and a second sealant layer disposed on the first sealant layer, wherein the first sealant layer has a melting point of 130° C. or more and 150° C. or less, a melt index (230° C., load 2.16 kg) measured by the ASTM D1238 method of 16 g / 10 min or more and 30 g / 10 min or less, and an average thickness of 10 ㎛ or more and 50 ㎛ or less, and the second sealant layer has a melting point of 120° C. or more and 160° C. or less, and ... a melt index (230° C., load 2.16 kg) measured by the ASTM D1238 method of 16 g / 10 min or more and 30 g / 10 min or less, and a melt index (230° C., load 2.16 kg) measured by the ASTM D1238 method of 16 g / 10 min or The melting index (230 ℃, load 2.16 kg) may be 5 g / 10 min or more and 15 g / 10 min or less, and the average thickness may be 30 ㎛ or more and 70 ㎛ or less.

[0077] According to one embodiment of the present invention, the pouch film laminate may have an average thickness of 170 μm or more and 200 μm or less. As a specific example, the pouch film laminate may have an average thickness of 170 ㎛ or more, 171 ㎛ or more, 172 ㎛ or more, 173 ㎛ or more, 174 ㎛ or more, 175 ㎛ or more, 176 ㎛ or more, 177 ㎛ or more, 178 ㎛ or more, 179 ㎛ or more, or 180 ㎛ or more, and may also have an average thickness of 200 ㎛ or less, 199 ㎛ or less, 198 ㎛ or less, 197 ㎛ or less, 196 ㎛ or less, 195 ㎛ or less, 194 ㎛ or less, 193 ㎛ or less, 192 ㎛ or less, 191 ㎛ or less, 190 ㎛ or less, 189 ㎛ or less, 188 ㎛ or less, 187 ㎛ or less, 186 ㎛ or less, or 185 ㎛ or less, and within this range, the secondary It is possible to protect the battery while preventing the secondary battery from becoming excessively thick due to the outer material.

[0078] According to one embodiment of the present invention, the pouch outer material may be manufactured by contacting at least one side of a lead tab film with an inner layer of the pouch film laminate, and then sealing the inner layer at a temperature of 205° C. or higher, for 1.5 seconds or longer and 2.7 seconds or shorter, under a pressure of 0.1 MPa or higher and 0.5 MPa or lower, so that the thickness of the inner layer at the sealing portion is less than 85% of the thickness of the inner layer of the pouch film laminate. As a specific example, during the sealing, the sealing temperature may be 205°C or higher, 206°C or higher, 207°C or higher, 208°C or higher, 209°C or higher, 210°C or higher, 211°C or higher, 212°C or higher, 213°C or higher, 214°C or higher, 215°C or higher, 216°C or higher, 217°C or higher, 218°C or higher, 219°C or higher, or 220°C or higher, and may also be 225°C or lower, 224°C or lower, 223°C or lower, 222°C or lower, 221°C or lower, 220°C or lower, 219°C or lower, 218°C or lower, 217°C or lower, 216°C or lower, or 215°C or lower. In addition, the sealing time may be 1.5 seconds or more, 1.6 seconds or more, 1.7 seconds or more, or 1.8 seconds or more, and further may be 2.7 seconds or less, 2.6 seconds or less, 2.5 seconds or less, or 2.4 seconds or less. In addition, the sealing pressure may be 0.1 MPa or more, or 0.2 MPa or more, and further may be 0.5 MPa or less, or 0.4 MPa or less. When the sealing temperature, time, and pressure are controlled in this manner, a high peel strength is secured for the sealing portion between the inner layer of the pouch film laminate and the lead tab film, and at the same time, the polymer material pushed out from the sealing portion at the tab portion is uniformly formed in the non-sealed portion, thereby preventing the thickness of the inner layer from becoming thinner, thereby preventing insulation failure and improving long-term reliability such as chemical resistance.

[0079] The present invention provides a secondary battery including the above pouch outer material.

[0080] According to one embodiment of the present invention, the secondary battery may include the pouch outer case and an electrode assembly accommodated in the pouch outer case.

[0081] According to one embodiment of the present invention, the secondary battery may be a lithium secondary battery.

[0082]

[0083] 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.

[0084]

[0085] Manufacturing Example 1

[0086] A first sealant layer having an average thickness of 30 ㎛ was formed by extruding polypropylene between one side of an aluminum film having an average thickness of 60 ㎛ as a barrier layer and one side of a non-stretched polypropylene film having an average thickness of 50 ㎛ as a second sealant layer, thereby manufacturing a film laminate having an aluminum film / first sealant layer / second sealant layer structure. In addition, a nylon film having an average thickness of 25 ㎛ and a polyethylene terephthalate having an average thickness of 12 ㎛ were each dry lamination-attached to the other side of the aluminum film, thereby manufacturing a pouch film laminate having a PET / nylon / aluminum film / first sealant layer / second sealant layer structure.

[0087] Here, the polypropylene forming the first sealant layer has a melting point of 145°C and a melting index (230°C, load 2.16 kg) of 24 g / 10 min measured by the ASTM D1238 method, and the non-stretched polypropylene forming the second sealant layer has a melting point of 140°C and a melting index (230°C, load 2.16 kg) of 12 g / 10 min measured by the ASTM D1238 method.

[0088]

[0089] Manufacturing Example 2

[0090] As a barrier layer, a first polypropylene layer and a second polypropylene layer were sequentially laminated on one side of an aluminum film having an average thickness of 60 ㎛, and co-extruded to simultaneously form a first sealant layer having an average thickness of 40 ㎛ and a second sealant layer having a thickness of 40 ㎛. Then, a nylon film having an average thickness of 25 ㎛ and a polyethylene terephthalate film having an average thickness of 12 ㎛ were each dry-laminated to the other side of the aluminum film to manufacture a pouch film laminate having a structure of PET / nylon / aluminum film / first sealant layer / second sealant layer.

[0091] Here, the polypropylene forming the first sealant layer has a melting point of 163°C and a melting index (230°C, load 2.16 kg) of 11 g / 10 min measured by the ASTM D1238 method, and the polypropylene forming the second sealant layer has a melting point of 143°C and a melting index (230°C, load 2.16 kg) of 9 g / 10 min measured by the ASTM D1238 method.

[0092]

[0093] Examples, comparative examples, and experimental examples

[0094] Using the pouch film laminate manufactured in Manufacturing Example 1, sealing of the lead tab film and the pouch film laminate was performed under the conditions described in Table 1 below, and using the pouch film laminate manufactured in Manufacturing Example 2, sealing of the lead tab film and the pouch film laminate was performed under the conditions described in Table 2 below.

[0095] For the seals manufactured in the above examples and comparative examples, the peel strength was measured using the following method, and the thickness change was observed and shown together in Table 1.

[0096]

[0097] * Peel strength of the sealing part (N / 15 mm): The lead tab film sealing part manufactured in the above examples and comparative examples was cut to a width of 15 mm to manufacture a specimen, and then the peel strength of the sealing part was measured using a universal testing machine (UTM) at a gauge distance of 20 mm and a peeling speed of 10 mm / min.

[0098]

[0099] * Thickness change: The pouch outer material was cut in a direction perpendicular to the lead tab film sealing portion manufactured in the above examples and comparative examples, and epoxy molding and polishing were performed on the cross-section. Then, a cross-sectional analysis of the lead tab film sealing portion and the adjacent area was performed using an optical device. From the optical image obtained from the optical device, in the area where the thickness of the inner layer increases adjacent to the lead tab film sealing portion, it was observed whether there was a point and / or area where the thickness of the inner layer was thinner than 80 ㎛, which is the total average thickness of the first sealant layer and the second sealant layer. If there was no thinning point and / or area, it was marked as OK, and if there was one or more thinning points and / or areas, it was marked as NG.

[0100] Additionally, the optical image for Example 17 is shown in FIG. 3, and the optical image for Example 18 is shown in FIG. 4.

[0101]

[0102] Separation sealing condition peeling strength thickness change temperature time pressure inner layer thickness residual rate 1)(℃)(s)(MPa)(%)(N / 15 mm)Comparative example 12001.80.270Cannot be manufacturedCannot be manufacturedExample 12001.80.280142OKComparative example 22001.80.285128OKComparative example 32001.80.290102OKComparative example 42001.80.470Cannot be manufacturedCannot be manufacturedExample 22001.80.480139OKComparative example 52001.80.485122OKComparative example 62001.80.490103OKComparative example 72002.40.270Cannot be manufacturedCannot be manufacturedExample 32002.40.280144OKComparative example 82002.40.285128OKComparative example 92002.40.290101OKComparative Example 102002.40.470Cannot be manufacturedCannot be manufacturedExample 42002.40.480142OKComparative Example 112002.40.485121OKComparative Example 122002.40.490105OKExample 52101.80.270165OKExample 62101.80.280152OKExample 72101.80.285138OKComparative Example 132101.80.290121OKExample 82101.80.470164OKExample 92101.80.480155OKExample 102101.80.485141OKComparative Example 142101.80.490120OKExample 112102.40.270166OKExample 122102.40.280155OKExample 132102.40.285133OKComparative Example 152102.40.290122OKExample 142102.40.470165OKExample 152102.40.480149OKExample 162102.40.485132OKComparative Example 162102.40.490128OKExample 172201.80.270174OKExample 182201.80.280168OKExample 192201.80.285149OKExample 202201.80.290135OKExample 212201.80.470177OKExample 222201.80.480168OKExample 232201.80.485154OKExample 242201.80.490140OKComparative Example 172202.40.270181N.GComparative Example 182202.40.280172N.GExample 252202.40.285159OKExample 262202.40.290142OKComparative Example 192202.40.470180N.GComparative Example 202202.40.480174N.GExample 272202.40.485155OKExample 282202.40.490147OK1) Inner layer thickness remaining ratio: The ratio of the thickness of the inner layer at the sealing portion to the thickness of the inner layer of the pouch film laminate.

[0103] Separation sealing condition peeling strength thickness change temperature time pressure inner layer thickness residual rate 1)(℃)(s)(MPa)(%)(N / 15 mm)Comparative Example 212001.80.270124OKComparative Example 222001.80.280109OKComparative Example 232001.80.28589OKComparative Example 242001.80.29088OKComparative Example 252001.80.470127OKComparative Example 262001.80.480111OKComparative Example 272001.80.48590OKComparative Example 282001.80.49091OKComparative Example 292002.40.270130OKComparative Example 302002.40.280119OKComparative Example 312002.40.28594OKComparison Example 322002.40.29089OKComparison Example 332002.40.470129OKComparison Example 342002.40.480112OKComparison Example 352002.40.48597OKComparison Example 362002.40.49090OKComparison Example 372101.80.270128OKComparison Example 382101.80.280118OKComparison Example 392101.80.28590OKComparison Example 402101.80.29086OKExample 292101.80.470131OKComparison Example 412101.80.480112OKComparison Example 422101.80.48592OKComparison Example 432101.80.49088OKComparison Example 442102.40.270129OKComparison Example 452102.40.280122OKComparison Example 462102.40.28597OKComparison Example 472102.40.29091OKExample 302102.40.470133OKComparison Example 482102.40.480121OKComparison Example 492102.40.48599OKComparison Example 502102.40.49089OKExample 312201.80.270139OKComparison Example 512201.80.280124OKComparison Example 522201.80.285100OKComparative Example 532201.80.29088OKExample 322201.80.470139OKComparative Example 542201.80.480127OKComparative Example 552201.80.485107OKComparative Example 562201.80.49093OKComparative Example 572202.40.270141OKComparative Example 582202.40.280122OKComparative Example 592202.40.285101OKComparative Example 602202.40.29089OKComparative Example 612202.40.470140OKComparative example 622202.40.480129OKComparative example 632202.40.485103OKComparative example 642202.40.49091OK1) Inner layer thickness remaining ratio: The ratio of the thickness of the inner layer at the sealing portion to the thickness of the inner layer of the pouch film laminate.

[0104] As shown in Tables 1 and 2 above and FIGS. 3 and 4, the pouch outer materials of Examples 1 to 32 according to the present invention secure high peel strength at the lead tab film sealing portion, and when the cross-section of the pouch outer materials is checked in a direction perpendicular to the lead tab film sealing portion, it can be confirmed that in the region where the thickness of the inner layer increases adjacent to the lead tab film sealing portion, there is no region where the thickness of the inner layer is thinner than the average thickness of the inner layer in the receiving space region. In particular, it can be confirmed that Examples 5, 8, 11, 14, 17, 18, 21 and 22 exhibit particularly high peel strengths.

[0105] On the other hand, the pouch outer materials of Comparative Examples 1 to 64 were either impossible to manufacture, had very low peel strength, or had high peel strength, but when the cross-section of the pouch outer material was checked in a direction perpendicular to the lead tab film sealing portion, in a region where the thickness of the inner layer increased adjacent to the lead tab film sealing portion, there was an area where the thickness of the inner layer was thinner than the average thickness of the inner layer in the receiving space region, so it could be expected that there was a problem with long-term reliability.

Claims

1. A pouch film laminate comprising an outer layer, a barrier layer, and an inner layer, The peel strength of the lead tab film seal formed by contacting at least one side of the lead tab film and then sealing the inner layer is 130 N / 15 mm or more, A pouch outer case in which, when a cross-section of the pouch outer case is checked in a direction perpendicular to the lead tab film sealing portion, in a region where the thickness of the inner layer increases adjacent to the lead tab film sealing portion, there is no region in which the thickness of the inner layer is thinner than the average thickness of the inner layer in the receiving space region.

2. In paragraph 1, A pouch outer shell, wherein the inner layer comprises at least one selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber.

3. In paragraph 1, The above inner layer is a pouch outer material having an average thickness of 40 ㎛ or more and 120 ㎛ or less.

4. In paragraph 1, A pouch outer shell, wherein the inner layer includes a first sealant layer disposed on the barrier layer, and a second sealant layer disposed on the first sealant layer.

5. In paragraph 4, The above first sealant layer is a pouch outer material having a melting point of 130°C or higher and 150°C or lower.

6. In paragraph 4, The above first sealant layer is a pouch outer material having a melting point of more than 150°C and less than 180°C.

7. In paragraph 4, The pouch outer shell of the first sealant layer has a melting index of 16 g / 10 min or more and 30 g / 10 min or less, as measured under conditions of a temperature of 230°C and a load of 2.16 kg according to the ASTM D1238 method.

8. In paragraph 4, The pouch outer shell of the first sealant layer has a melting index of 5 g / 10 min or more and less than 16 g / 10 min, as measured under the conditions of a temperature of 230 ℃ and a load of 2.16 kg according to the ASTM D1238 method.

9. In paragraph 4, The above first sealant layer is a pouch outer material having an average thickness of 10 ㎛ or more and 50 ㎛ or less.

10. In paragraph 4, The above second sealant layer is a pouch outer material having a melting point of 120°C or higher and 160°C or lower.

11. In paragraph 4, The second sealant layer is a pouch outer material having a melting index of 5 g / 10 min or more and 15 g / 10 min or less, as measured under conditions of a temperature of 230°C and a load of 2.16 kg according to the ASTM D1238 method.

12. In paragraph 4, The above second sealant layer is a pouch outer material having an average thickness of 30 ㎛ or more and 70 ㎛ or less.

13. In paragraph 1, The above pouch film laminate is a pouch outer material having an average thickness of 170 ㎛ or more and 200 ㎛ or less.

14. In paragraph 1, A pouch outer material, wherein the lead tab film sealing portion is formed by sealing at least one surface of the lead tab film and the inner layer, after contacting them, at a temperature of 205° C. or higher, for 1.5 seconds or longer and 2.7 seconds or shorter, and at a pressure of 0.1 MPa or higher and 0.5 MPa or lower, such that the thickness of the inner layer at the sealing portion is less than 85% of the thickness of the inner layer of the pouch film laminate.

15. A secondary battery comprising a pouch outer case according to any one of claims 1 to 14.

Images