Pouch cell and manufacturing method thereof

Abstract

The present invention relates to a pouch cell that can prevent cracks from occurring in the bridge portion of the pouch due to gases generated during charging or discharging, and a method for manufacturing the same. A method for manufacturing a pouch cell according to the present invention includes the step of (a) forming a pouch film including a metal layer such that a pair of cup portions capable of accommodating an electrode assembly are formed on both sides of a bridge portion in the pouch film, and in the step (a), the pouch film may be formed to satisfy the formula T / D>0.006, where T mm is the thickness of the metal layer of the bridge portion after forming, and D mm is the depth of the cup portions.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0171495, filed December 9, 2022, Korean Patent Application No. 10-2023-0048848, filed April 13, 2023, and Korean Patent Application No. 10-2023-0175274, filed December 6, 2023, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a pouch cell and a manufacturing method thereof, and more particularly to a secondary battery pouch cell capable of being charged and discharged and a manufacturing method thereof. [Background technology]

[0003] In recent years, with the depletion of fossil fuels causing rising energy costs and growing concerns about environmental pollution, the need for environmentally friendly alternative energy sources has become an essential factor for future life. Therefore, research into various electricity production technologies, such as solar, wind, and tidal power, is ongoing, and there has also been great interest in power storage devices such as batteries to more efficiently use the electrical energy produced in this way.

[0004] Furthermore, with the increasing technological development and demand for battery-based electronic mobile devices and electric vehicles, the demand for batteries as an energy source is increasing rapidly, and as a result, much research is being conducted on batteries that can meet various needs.

[0005] Batteries that store electrical energy can generally be divided into primary batteries and secondary batteries. Primary batteries are disposable, consumable batteries, while secondary batteries are rechargeable batteries manufactured using materials that can undergo repeated oxidation and reduction processes between electric current and materials. That is, when a reduction reaction occurs in a material due to electric current, the power source is charged, and when an oxidation reaction occurs in the material, the power source is discharged. Electricity is generated as this charge-discharge cycle is repeated.

[0006] Secondary batteries are classified into cylindrical cells, pouch cells, prismatic cells, etc., depending on their shape. Among them, a pouch cell may include an electrode assembly in which a positive electrode, a negative electrode, a separator, etc. are stacked inside a pouch.

[0007] Generally, a pouch cell may be manufactured in a form in which an electrode assembly is accommodated in a cup portion of a pouch film, where the cup portion may be formed by a process of molding the pouch film.

[0008] Meanwhile, to increase energy density, a pouch cell may be manufactured in which the cup portions of the pouch housing the electrode assembly are formed on both sides of the pouch in the thickness direction. Such a pouch cell has a problem in that cracks may occur in the bridge portion formed between the two cup portions due to gas generated from the inside, damaging the bridge portion. Damage to the bridge portion may cause the pouch cell to malfunction.

[0009] Therefore, there is a need for a pouch cell that can prevent damage to the bridge portion and a method for manufacturing the same. Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a pouch cell and a manufacturing method thereof that improve safety by preventing cracks from occurring in the bridge portion of the pouch due to gases generated during the charging or discharging process of the pouch cell. [Means for solving the problem]

[0011] A method for manufacturing a pouch cell according to the present invention includes the step of (a) forming a pouch film including a metal layer such that a pair of cup portions capable of accommodating an electrode assembly are formed on both sides of a bridge portion in the pouch film, and in the step (a), the pouch film may be formed to satisfy the formula T / D>0.006, where T mm is the thickness of the metal layer of the bridge portion after forming, and D mm is the depth of the cup portions.

[0012] In the step (a), the metal layer may be shaped so that the thickness of the metal layer at the bridge portion after shaping is 0.8 times or more the thickness of the metal layer before shaping.

[0013] The method for manufacturing a pouch cell further includes the steps of (b) placing an electrode assembly in the cup portion and folding the pouch film based on the bridge portion so that the pair of cup portions cover the electrode assembly, and (c) sealing the outer edge of the pouch film in the folded state, wherein in the step (c), the sealing may be performed so that the shortest linear distance between the sealed portion and the cup portion is 0.5 mm or more and 1.5 mm or less.

[0014] The method for manufacturing a pouch cell further includes the steps of (b) placing an electrode assembly in the cup portions and folding the pouch film based on the bridge portions so that the pair of cup portions cover the electrode assembly, and (c) sealing the open portion of the pouch film in the folded state, wherein the step (c) may include the steps of (c-1) sealing the outer edge of the pouch film, and (c-2) forming an additional seal portion with a gap of 0.5 mm to 1.5 mm between the cup portions.

[0015] A method for manufacturing a pouch cell according to the present invention includes the step of (a) forming a pouch film including a metal layer so that a pair of cup portions capable of accommodating an electrode assembly are formed on both sides of a bridge portion in the pouch film, and in the step (a), the metal layer may be formed so that the thickness of the metal layer in the bridge portion is reduced by 20% or less.

[0016] The metal layer may include aluminum (Al).

[0017] A pouch cell according to the present invention includes an electrode assembly and a pouch including a metal layer, the pouch having a shape folded on both sides based on a bridge portion to cover the electrode assembly, the pouch including a cup portion having a space therein for accommodating the electrode assembly, and the pouch may satisfy a mathematical formula of T / D>0.006, where T mm is the thickness of the metal layer of the bridge portion and D mm is the depth of the cup portion.

[0018] The pouch may include a seal portion spaced apart from the cup portion and sealed to isolate the electrode assembly from the outside, and the shortest distance between the cup portion and the seal portion may be 0.5 mm or more and 1.5 mm or less.

[0019] The sealing portion may further include an outer sealing portion spaced a predetermined distance from the cup portion, and an additional sealing portion disposed between the outer sealing portion and the cup portion, and the distance between the additional sealing portion and the cup portion may be 0.5 mm or more and 1.5 mm or less.

[0020] The pouch cell may have the bridge portion formed at one end of the cup portion, and the additional seal portion disposed such that one end thereof is aligned with one end of the cup portion.

[0021] The additional seal portion may have a shape in which its width gradually decreases from the outer seal portion toward the cup portion.

[0022] In the pouch, the thickness of the metal layer in the bridge portion may be 0.8 times or more the thickness of the metal layer in the seal portion. [Effects of the Invention]

[0023] The method for manufacturing a pouch cell according to the present invention includes the step of (a) molding a pouch film including a metal layer so that a pair of cup portions are formed in the pouch film, and in the step (a), the pouch film may be molded so as to satisfy the formula T / D>0.006, where T mm is the thickness of the metal layer of the cup portions after molding, and D mm is the depth of the cup portions.

[0024] This can prevent cracks from occurring in the bridge portion of the pouch due to gases generated during charging or discharging.

[0025] Furthermore, the efficiency of the manufacturing process of the pouch cell can be improved.

[0026] Furthermore, by preventing damage to the bridge portion of the pouch, the safety of the pouch cell can be improved.

[0027] The effects of the present invention are not limited to the above-mentioned examples, and various other effects are included within the present specification. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a flowchart that schematically illustrates a method for manufacturing a pouch cell according to an embodiment of the present invention. [Figure 2] 1 is a perspective view schematically illustrating a pouch cell according to an embodiment of the present invention; [Figure 3] FIG. 10 is a front view schematically illustrating a state in which a crack occurs in a pouch cell according to a comparative example of the present invention. [Figure 4] 1 is a perspective view schematically illustrating a pouch film according to one embodiment of the present invention. [Figure 5]1 is a plan view schematically illustrating a seal portion of a pouch cell according to an embodiment of the present invention viewed from above. [Figure 6] 10 is a plan view schematically illustrating a sealing portion of a pouch cell according to another embodiment of the present invention viewed from above. FIG. [Figure 7] 10 is a plan view schematically illustrating a sealing portion of a pouch cell according to yet another embodiment of the present invention, viewed from above. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0029] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention will now be described in detail with reference to the accompanying drawings, in order to enable those skilled in the art to easily carry out the present invention. However, the present invention may be embodied in various different forms and should not be construed as being limited to the following embodiments.

[0030] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may obscure the gist of the present invention are omitted, and in this specification, when referring to components in each drawing, the same or similar reference symbols are used throughout the specification for the same or similar components.

[0031] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0032] Pouch cell manufacturing method FIG. 1 is a flow chart that schematically illustrates a method for manufacturing a pouch cell according to an embodiment of the present invention, and FIG. 2 is a perspective view that schematically illustrates a pouch cell 10 according to an embodiment of the present invention.

[0033] A method for manufacturing a pouch cell according to an embodiment of the present invention may be a method for manufacturing a secondary battery capable of being charged and discharged. Specifically, the method for manufacturing a pouch cell may be a method for manufacturing a pouch cell 10 having an electrode assembly disposed inside a pouch 100.

[0034] 1, a method for manufacturing a pouch cell according to an embodiment of the present invention may include a step (S1) of forming a pouch film 100-1 including a metal layer 102 so that a pair of cup portions 110 are formed in the pouch film 100-1. Hereinafter, this step will be referred to as step (a).

[0035] 2, a pouch cell 10 manufactured by a pouch cell manufacturing method according to an embodiment of the present invention may have an electrode assembly including a negative electrode, a positive electrode, and a separator disposed inside a pouch 100. Here, the pouch 100 may be disposed in a form that encases the electrode assembly. Specifically, the pouch cell 10 may refer to a secondary battery in which an electrode assembly including a negative electrode, a positive electrode, and a separator is housed inside the pouch 100 together with an electrolyte.

[0036] Meanwhile, the electrode assembly may have a stacked form or a wound jelly roll form in which the negative electrode, positive electrode, and separator are stacked, and the pouch 100 may contain the electrode assembly. The pouch 100 may also include a cup portion 110 formed to contain the electrode assembly and the electrolyte therein. Here, in step (a) of the method for manufacturing a pouch cell according to an embodiment of the present invention, the cup portion 110 may be formed in the pouch film 100-1.

[0037] The pouch film 100-1 to be formed may be a film in which multiple layers having different properties are laminated together, and may include a metal layer 102.

[0038] The cup portion 110 may be formed in the pouch film 100-1 including the metal layer 102 by a pouch forming device or the like. The pouch forming device may have various configurations. For example, the pouch forming device may include a punch and a die, and the punch may pressurize the pouch film 100-1 placed in the die to form the cup portion 110.

[0039] 2, the cup portion 110 of the pouch 100 may have a space formed therein to accommodate an electrode assembly and an electrolyte. Meanwhile, the pouch cell may be manufactured in various ways. For example, a pouch cell may be manufactured by joining two pouch films each having a cup portion formed therein so that they face each other, or by folding a pouch film each having a pair of cup portions formed therein to form a space between the pair of cup portions to accommodate an electrode assembly. A method for manufacturing a pouch cell according to one embodiment of the present invention will be described using, as an example, a method in which a pouch film each having a pair of cup portions formed therein is folded to form a space between the pair of cup portions to accommodate an electrode assembly.

[0040] Therefore, the pouch film 100-1 used in the method for manufacturing a pouch cell according to an embodiment of the present invention may be formed to have a pair of cup portions 110. Here, the pair of cup portions 110 may be formed on both sides of the bridge portion 130. That is, the bridge portion 130 may be provided between the pair of cup portions 110. When the pouch film 100-1 is folded, a space capable of accommodating an electrode assembly may be formed between the pair of cup portions 110 facing each other. Here, the pouch film 100-1 may be folded based on the bridge portion 130.

[0041] As described above, the bridge portion 130 may be formed between the pair of cup portions 110. Therefore, after the pouch film 100-1 is folded, the bridge portion 130 may be formed at one end of the cup portion 110.

[0042] FIG. 3 is a front view schematically illustrating a state in which a crack occurs in a pouch cell according to a comparative example of the present invention.

[0043] 3, in a conventional pouch cell manufactured by folding a pouch film having a pair of cup portions, cracks occur at the folding reference point. Specifically, when folding is performed based on the bridge portion 130, cracks occur in the bridge portion 130 of the pouch 100. In this regard, gas may be generated inside the pouch 100 as the pouch cell 10 is repeatedly charged and discharged. The gas inside the pouch 100 applies pressure to the pouch 100, causing cracks in the bridge portion 130, which is relatively weak in rigidity. That is, the gas increases the pressure inside the pouch 100, and the increased pressure may cause cracks in the bridge portion 130, which is relatively weak to pressure.

[0044] Furthermore, cracks may occur in the bridge portion 130 during the manufacturing process of the pouch cell 10. For example, cracks may occur in the bridge portion 130 due to gas generated inside the pouch during the activation process. In addition, cracks may occur in the bridge portion 130 due to various physical factors during the manufacturing process of the pouch cell 10.

[0045] FIG. 4 is a perspective view schematically illustrating a pouch film 100-1 according to one embodiment of the present invention.

[0046] The pouch film 100-1 used in the method for manufacturing a pouch cell according to one embodiment of the present invention can include multiple layers. For example, the pouch film 100-1 can include an inner layer 101, a metal layer 102, and an outer layer 103.

[0047] The pouch film 100-1 used in the production of the pouch cell 10 of the present invention will be specifically described.

[0048] Referring to FIG. 4, a pouch film 100-1 can include an inner layer 101, a metal layer 102, and an outer layer 103, and can optionally further include a stretch-assist layer.

[0049] The inner layer 101 may be made of a polymer and may be formed as the innermost layer to be in direct contact with the electrode assembly, where the innermost layer may refer to the last layer from the outer layer 103 toward the electrode assembly.

[0050] The polymer used to form the inner layer 101 may be one or more materials 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. In particular, polyolefin resins such as polypropylene (PP) or polyethylene (PE) are commonly used. Polypropylene (PP) is primarily used to form the inner layer 101 due to its excellent mechanical properties, such as tensile strength, rigidity, surface hardness, abrasion resistance, and heat resistance, as well as its excellent chemical properties, such as corrosion resistance. Furthermore, the inner layer 101 may be made of unstretched polypropylene (cationized polypropylene), acid-modified polypropylene, or polypropylene-butylene-ethylene terpolymer. Here, the acid-modified polypropylene may be maleic anhydride polypropylene (MAH PP). The inner layer 101 may have a single film structure made of any one material, or a composite film structure made of two or more materials each forming a layer.

[0051] On the other hand, the pouch film 100-1 used in the method for producing a pouch cell can have an inner layer 101 with a thickness of 30 μm to 100 μm, preferably 40 μm to 90 μm, and particularly 50 μm to 85 μm.

[0052] The metal layer 102 ensures the mechanical strength of the pouch 100, blocks the inflow and outflow of gas or moisture from the outside of the pouch cell 10, and can prevent leakage of the electrolyte.

[0053] The metal layer 102 may include, but is not limited to, a metal selected from the group consisting of copper (Cu), aluminum (Al), nickel (Ni), iron (Fe), carbon (C), chromium (Cr), manganese (Mn), and alloys containing two or more of these. Preferably, the metal layer 102 may include a metal selected from an aluminum alloy and stainless steel (SUS).

[0054] Aluminum alloys and stainless steels can ensure a certain level of mechanical strength and are light in weight, and can also ensure the electrochemical properties of the electrode assembly and electrolyte, as well as heat dissipation.

[0055] The aluminum alloy may contain various materials, such as one or more selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), and zinc (Zn).

[0056] The metal layer 102 may have a single layer structure or a multi-layer structure, for example, a multi-layer metal layer 102 may be made of an aluminum alloy layer and a stainless steel layer.

[0057] On the other hand, the pouch film 100-1 used in the method for manufacturing a pouch cell may have a thickness of the metal layer 102 of 20 μm to 100 μm, preferably 40 μm to 80 μm, and particularly 50 μm to 70 μm.

[0058] The outer layer 103 is made of a polymer and is formed as the outermost layer, protecting the pouch cell 10 from external friction and impact and electrically insulating the electrode assembly from the outside. Here, the outermost layer may refer to the last layer farthest from the electrode assembly relative to the inner layer 101.

[0059] The polymer used to form the outer layer 103 may be one or more materials 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. In particular, a polymer such as polyethylene terephthalate (PET), which has abrasion resistance and heat resistance, is preferably used. Furthermore, the outer layer 103 may have a single film structure made of any one material, or a composite film structure formed by layers of two or more materials.

[0060] On the other hand, the pouch film 100-1 used in the method for producing a pouch cell can have an outer layer 103 with a thickness of 5 μm to 25 μm, preferably 6 μm to 20 μm, and particularly 7 μm to 15 μm.

[0061] The pouch film 100-1 used to manufacture the pouch cell 10 may further include a stretch-assist layer disposed between the metal layer 102 and the outer layer 103.

[0062] The stretching-assist layer is made of a polymer and can prevent the metal layer 102 and the outer layer 103 from peeling off when stretched.

[0063] The polymer forming the stretching assisting layer may be one or more materials 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. Nylon resin, in particular, is easily bonded to the polyethylene terephthalate (PET) of the outer layer 103 and exhibits similar behavior during stretching to the aluminum alloy of the metal layer 102. Therefore, nylon resin is typically used as the polymer forming the stretching assisting layer. The stretching assisting layer may have a single film structure made of any one material, or a composite film structure formed by layers of two or more materials.

[0064] On the other hand, the pouch film 100-1 used in the method for producing a pouch cell may have a thickness of the stretching auxiliary layer of 15 μm to 50 μm, preferably 25 μm to 45 μm, and particularly 25 μm to 40 μm.

[0065] The thickness of the pouch film 100-1 including the inner layer 101, the metal layer 102, the outer layer 103, and the stretching auxiliary layer can be selected within an appropriate range depending on the use of the pouch cell. For example, the thickness of the pouch film 100-1 can be 70 μm to 275 μm, 90 μm to 250 μm, or 100 μm to 220 μm.

[0066] As an example of a method for preventing cracks from occurring in the bridge portion 130, in step (a) of the pouch cell manufacturing method according to one embodiment of the present invention, when the thickness of the metal layer 102 of the bridge portion 130 after molding is T mm and the depth of the cup portion 110 is D mm, the pouch film 100-1 can be molded to satisfy the formula T / D>0.006.

[0067] When the cup portions 110 are formed in the pouch film 100-1, the thickness of the portion where the cup portions 110 are formed and the thickness of the bridge portion 130 provided between the pair of cup portions 110 may be reduced. Therefore, the thickness of the metal layer 102 of the pouch film 100-1 that forms the cup portions 110 and the metal layer 102 of the pouch film 100-1 that forms the bridge portions 130 may also be reduced. In this regard, in the formula T / D>0.006, T may refer to the thickness of the metal layer 102 of the bridge portion 130 that has become thinner after forming.

[0068] 4, after molding, the cup portion 110 may have a depth. Here, a mathematical formula for a condition that can prevent cracks from occurring in the bridge portion 130 of the pouch 100 can be obtained through experiments. The experiments were conducted at various molding depths, and this mathematical formula can be a relationship between the depth D at which the cup portion 110 is molded and the thickness T of the metal layer of the bridge portion 130 after molding. In other words, this relationship can be a condition for preventing cracks from occurring in the bridge portion 130 of the pouch 100.

[0069] Specific experimental results can be seen in Tables 1 and 2 below.

[0070] [Table 1]

[0071] [Table 2]

[0072] Referring to Table 1, it can be seen that cracks do not occur in the bridge portion 130 when the T / D value exceeds 0.006. On the other hand, referring to Table 2, when the T / D value is less than 0.006, cracks occur in the bridge portion 130 due to repeated charging and discharging of the pouch cell 10. Furthermore, cracks also occur when the T / D value is 0.006. As an example of a method for preventing cracks from occurring in the bridge portion 130, in step (a) of the method for manufacturing a pouch cell according to an embodiment of the present invention, the metal layer may be formed so that the thickness T of the metal layer 102 of the bridge portion 130 after molding is at least 0.8 times the thickness of the metal layer before molding. That is, the thickness T of the metal layer 102 of the bridge portion 130 after molding may be at least 80% and at most 100% of the thickness of the metal layer before molding.

[0073] As described above, the thickness of the metal layer 102 of the cup portion 110 and the bridge portion 130 may become thin during the process of forming the cup portion 110 on the pouch film 100-1. Here, when the thickness T of the metal layer 102 of the bridge portion 130 after forming is 80% or more of the thickness before forming, no cracks occurred in the bridge portion 130 of the pouch cell 10. Here, 80% may be a value obtained through repeated experiments.

[0074] Meanwhile, in order to prevent cracks from occurring in the bridge portion 130, in step (a) of the pouch cell manufacturing method, the metal layer may be formed so that the thickness of the metal layer 102 on the cup portion side surface portion 111 after forming is at least 0.8 times the thickness of the metal layer before forming. That is, the thickness of the metal layer 102 on the cup portion side surface portion 111 after forming may be at least 80% and at most 100% of the thickness of the metal layer before forming. Here, the cup portion side surface portion 111 may refer to a portion that surrounds the side of the cup portion 110 so as to form a space in the cup portion 110 to accommodate an electrode assembly (see FIG. 4).

[0075] The process of forming the cup portion 110 in the pouch film 100-1 may result in a large relative change in thickness between the bridge portion 130 and the cup portion side portion 111. In this regard, the method for manufacturing a pouch cell according to an embodiment of the present invention can set a change in the thickness of the metal layer between the bridge portion 130 and the cup portion side portion 111. This can effectively prevent cracks from occurring in the bridge portion 130 of the completed pouch cell 10.

[0076] A method for manufacturing a pouch cell according to an embodiment of the present invention may further include a step (S2) of placing an electrode assembly in the cup portions 110 and folding the pouch film 100-1 between the pair of cup portions 110 so that the pair of cup portions 110 cover the electrode assembly. Specifically, the pouch film 100-1 may be folded based on the bridge portions 130. The method may also include a step (S3) of sealing the outer edge of the folded pouch film 100-1 (see FIG. 1). Herein, the outer edge of the folded pouch film 100-1 may be sealed by heat and pressure. Hereinafter, the sealing step will be referred to as step (c).

[0077] FIG. 5 is a plan view schematically illustrating the seal portion 120 of the pouch cell 10 according to one embodiment of the present invention as viewed from above.

[0078] As an example of a method for more efficiently preventing cracks from occurring in the bridge portion 130, in step (c) of the method for manufacturing a pouch cell according to an embodiment of the present invention, sealing may be performed so that the shortest linear distance L between the seal portion 120 and the cup portion 110 is 0.5 mm or more and 1.5 mm or less. Here, the seal portion 120 may refer to the sealed portion.

[0079] Meanwhile, the pouch film 100-1 may have a substantially rectangular shape when viewed from above. Here, when the pouch film 100-1 is folded based on the bridge portion 130, three areas may be opened in addition to the area where the bridge portion 130 is formed. Specifically, there may be three corners to be sealed. In step (c), the three corners may be sealed so that the electrode assembly accommodated in the cup portion 110 can be sealed from the outside.

[0080] In this regard, in step (c), the sealing may be performed so that the shortest linear distance L between the seal portion 120 and the cup portion 110 is 0.5 mm or more and 1.5 mm or less. Specifically, when sealing the corners formed on both sides of the bridge portion 130 as well as the corner formed on the opposite side of the bridge portion 130 from the cup portion 110 among the three corners, the sealing may be performed so that the shortest linear distance L between the seal portion 120 and the cup portion 110 is 0.5 mm or more and 1.5 mm or less. Preferably, in step (c), the sealing may be performed so that the shortest linear distance L between the seal portion 120 and the cup portion 110 is 1 mm or less.

[0081] The pouch cell 10 sealed so that the distance L between the cup portion 110 and the seal portion 120 is 0.5 mm or more and 1.5 mm or less can prevent cracks in the bridge portion 130. Here, the value related to the distance may be a value obtained through repeated experiments.

[0082] According to an experiment, a pouch cell 10 in which the distance L between the cup portion 110 and the sealing portion 120 is 0.5 mm or more and 1.5 mm or less did not experience cracks in the bridge portion 130 even under relatively high pressure. Therefore, the pouch cell 10 according to an embodiment of the present invention can delay or prevent damage such as cracks from occurring in the bridge portion 130.

[0083] FIG. 6 is a plan view schematically illustrating a seal portion 120 of a pouch cell 10 according to another embodiment of the present invention, viewed from above.

[0084] A method for manufacturing a pouch cell according to another embodiment of the present invention may further include a step of placing an electrode assembly in the cup portions 110 and folding the pair of cup portions 110 so that the pair of cup portions 110 cover the electrode assembly. Also, a step of sealing the open portion of the folded pouch film 100-1 may further be included. Hereinafter, the sealing step will be referred to as step (c).

[0085] As an example of a method for more efficiently preventing cracks from occurring in the bridge portion 130, step (c) of the method for manufacturing a pouch cell according to another embodiment of the present invention may include steps (c-1) and (c-2). Here, step (c-1) may be a step of sealing the outer edge of the pouch film 100-1, and step (c-2) may be a step of forming an additional seal portion 122 such that the distance L between the folded portion and the pair of cup portions 110 is 0.5 mm or more and 1.5 mm or less. Here, the outer edge of the pouch film 100-1 may refer to the remaining outside other than one end of the cup portions 110 that has been folded and already sealed.

[0086] In step (c) of the pouch cell manufacturing method, step (c-1) may be performed followed by step (c-2), or steps (c-1) and (c-2) may be performed simultaneously.

[0087] 6, the seal portion 120 of the pouch cell 10 manufactured by the pouch cell manufacturing method according to another embodiment of the present invention may include an outer seal portion 121 and an additional seal portion 122. Here, the outer seal portion 121 may be disposed relatively farther away from the cup portion 110 than the additional seal portion 122, and the additional seal portion 122 may be disposed between the outer seal portion 121 and the cup portion 110. The outer seal portion 121 may be formed in step (c-1), and the additional seal portion 122 may be formed in step (c-2).

[0088] Experiments have shown that the entire sealing portion 120 does not need to form a gap of 0.5 mm to 1.5 mm from the cup portion 110. That is, when the gap L between the bridge portion 130, where cracks occur, and the sealing portion 120 is 0.5 mm to 1.5 mm, cracks can be prevented. Therefore, in order to satisfy this condition and reduce the sealed portion, step (c) of the pouch cell manufacturing method according to another embodiment of the present invention can include step (c-2).

[0089] 6, the additional seal portion 122 may be formed on the same line as one end of the cup portion 110 where the bridge portion 130 is formed. Also, the length of the additional seal portion 122 may be shorter than the length of the outer seal portion 121. Therefore, a relatively large space may remain unsealed between the outer seal portion 121 and the cup portion 110. Because the unsealed space is relatively large, additional processes such as welding the electrode assembly and the electrode lead may be performed efficiently.

[0090] FIG. 7 is a plan view schematically illustrating a seal portion 120 of a pouch cell 10 according to yet another embodiment of the present invention, viewed from above.

[0091] Referring to FIG. 7, in a method for manufacturing a pouch cell according to yet another embodiment of the present invention, the additional seal portion 122 may be manufactured to have a shape whose width gradually decreases as it approaches the cup portion 110 from the outer seal portion 121.

[0092] If the width of the additional seal portion 122 gradually decreases as it approaches the cup portion 110 from the outer seal portion 121, the area of ​​the portion not sealed between the outer seal portion 121 and the cup portion 110 may become larger. Therefore, the process using the portion not sealed may be performed more efficiently.

[0093] The method for manufacturing a pouch cell may delay or prevent cracks from occurring in the bridge portion 130 even if it includes one of the features of the method for manufacturing a pouch cell for preventing cracks from occurring in the bridge portion 130 described above. However, in order to more efficiently prevent cracks from occurring in the bridge portion 130, the method for manufacturing a pouch cell may include all of the features described above.

[0094] Pouch Cell The pouch cell 10 according to one embodiment of the present invention can be a secondary battery that can be charged and discharged and has an electrode assembly disposed inside the pouch 100 .

[0095] In the pouch cell 10 according to one embodiment of the present invention, an electrode assembly including a negative electrode, a positive electrode, and a separator may be disposed inside the pouch 100 (see FIG. 2). Here, the pouch 100 may be disposed in a form that encases the electrode assembly. Specifically, the pouch cell 10 may refer to a secondary battery in which an electrode assembly including a negative electrode, a positive electrode, and a separator is housed inside the pouch 100 together with an electrolyte.

[0096] A pouch cell 10 according to an embodiment of the present invention may include an electrode assembly and a pouch 100. The pouch 100 may include a metal layer 102 and may have a shape in which both sides are folded based on a bridge portion 130 so as to cover the electrode assembly. The pouch 100 may also include a cup portion 110 that accommodates the electrode assembly.

[0097] As an example of a configuration for preventing cracks from occurring in the bridge portion 130, the pouch 100 of the pouch cell 10 according to one embodiment of the present invention can satisfy the formula T / D>0.006 when the thickness of the metal layer 102 of the bridge portion 130 is T mm and the depth of the cup portion 110 is D mm.

[0098] In this regard, repeated charging and discharging of the pouch cell 10 may generate gas inside the pouch 100. The gas inside the pouch 100 applies pressure to the pouch 100, which may cause cracks in the bridge portion 130, which is relatively weak against pressure. That is, the gas increases the pressure inside the pouch 100, and the increased pressure may cause cracks in the bridge portion 130, which is relatively weak against pressure.

[0099] When the thickness of the metal layer 102 of the bridge portion 130 is T mm and the depth of the cup portion 110 is D mm, a pouch cell 10 including a pouch 100 that satisfies the formula T / D>0.006 can prevent cracks from occurring in the bridge portion 130.

[0100] The pouch 100 of the pouch cell 10 can include a cup portion 110 and a seal portion 120 .

[0101] As another example of a configuration for preventing cracks in the bridge portion 130, in the pouch 100 of the pouch cell 10 according to one embodiment of the present invention, the thickness T of the metal layer 102 of the bridge portion 130 may be 0.8 times or more the thickness T' of the metal layer 102' of the seal portion 120.

[0102] In this regard, the thicknesses of the layers constituting the pouch 100 may vary depending on the manufacturing process of the pouch cell 10. Furthermore, the thicknesses of the layers may vary depending on the portion of the pouch 100. For example, the thicknesses of the inner layer 101, metal layer 102, and outer layer 103 of the bridge portion 130 may be different from the thicknesses of the inner layer 101', metal layer 102', and outer layer 103' of the seal portion 120.

[0103] Because the bridge portion 130 is provided between the pair of cup portions 110, it can be affected by the molding of the cup portions 110 during the manufacturing process of the pouch 100. On the other hand, the seal portion 120 can be unaffected by the molding during the manufacturing process of the pouch 100. Therefore, the thickness of the metal layer 102 of the bridge portion 130 can vary during the manufacturing process, while the thickness of the metal layer 102' of the seal portion 120 can vary little during the manufacturing process. Here, a difference in thickness can occur between the metal layer 102 of the bridge portion 130 and the metal layer 102' of the seal portion 120.

[0104] According to the results of repeated experiments, cracks do not occur in the bridge portion 130 of the pouch 100 when the thickness T of the metal layer 102 of the bridge portion 130 is 0.8 times or more the thickness T' of the metal layer 102' of the seal portion 120. That is, the thickness T of the metal layer 102 of the bridge portion 130 at which cracks do not occur in the bridge portion 130 of the pouch 100 can be 80% to 100% of the thickness T' of the metal layer 102' of the seal portion 120. As an example of an additional configuration for more efficiently preventing cracks from occurring in the bridge portion 130, the pouch 100 of the pouch cell 10 according to one embodiment of the present invention may have a shortest distance L between the cup portion 110 and the seal portion 120 of 0.5 mm to 1.5 mm. Preferably, the shortest distance L between the cup portion 110 and the seal portion 120 of the pouch 100 of the pouch cell 10 can be 1.0 mm or less. This value can be an experimentally obtained value.

[0105] When the seal portion 120 of the pouch 100 is formed with a distance of 0.5 mm to 1.5 mm from the cup portion 110, cracks can be prevented from occurring in the bridge portion 130 due to pressure from gas inside the pouch 100. In addition, even if a stronger pressure acts on the pouch 100, damage to the bridge portion 130 can be delayed or prevented.

[0106] FIG. 6 is a plan view schematically illustrating a seal portion 120 of a pouch cell 10 according to another embodiment of the present invention, viewed from above.

[0107] 6, the seal unit 120 of the pouch 100 according to another embodiment of the present invention may include an outer seal unit 121 and an additional seal unit 122. Specifically, the outer seal unit 121 of the seal unit 120 may be disposed at a predetermined distance from the cup portion 110, and the additional seal unit 122 may be disposed between the outer seal unit 121 and the cup portion 110. That is, the outer seal unit 121 may be disposed at a greater distance from the cup portion 110 than the additional seal unit 122.

[0108] Here, as an example of a configuration for more efficiently preventing cracks from occurring in the bridge portion 130, the pouch cell 10 according to another embodiment of the present invention may have a gap L between the additional seal portion 122 and the cup portion 110 of 0.5 mm or more and 1.5 mm or less.

[0109] The pouch cell 10 according to another embodiment of the present invention may have a larger unsealed space between the cup portion 110 and the sealing portion 120 than the pouch cell 10 according to one embodiment of the present invention. This prevents cracks from occurring in the bridge portion 130, and allows processes such as welding the electrode assembly and the electrode lead to be performed more efficiently.

[0110] Meanwhile, the bridge portion 130 of the pouch 100 may be formed at one end of the cup portion 110. Here, one end of the cup portion 110 may refer to the right end of the cup portion 110 with reference to FIG.

[0111] In the pouch cell 10 according to another embodiment of the present invention, the additional seal portion 122 may be arranged to be in line with one end of the cup portion 110. That is, the additional seal portion 122 may be arranged to contact one end of the outer seal portion 121. In this case, a larger space is formed between the cup portion 110 and a part of the outer seal portion 121 that is not in contact with the additional seal portion 122, and other processes that utilize this space may be performed more efficiently.

[0112] FIG. 7 is a plan view schematically illustrating a seal portion 120 of a pouch cell 10 according to yet another embodiment of the present invention, viewed from above.

[0113] 7, the additional seal portion 122 according to another embodiment of the present invention may have a shape in which the width gradually decreases from the outer seal portion 121 toward the cup portion 110. Here, the degree of width decrease may vary, and the shape of the additional seal portion 122 may vary.

[0114] If the additional seal portion 122 has a shape in which its width gradually decreases from the outer seal portion 121 toward the cup portion 110, a wider unsealed portion can be formed between the cup portion 110 and the outer seal portion 121. Therefore, the efficiency of the unsealed portion can be further improved.

[0115] The present invention has been described above using limited embodiments and drawings, but the present invention is not limited thereto, and various implementations are possible within the technical spirit of the present invention and the scope of the claims set forth below by a person having ordinary skill in the art to which the present invention pertains. [Explanation of symbols]

[0116] 10 pouch cells 100 pouches 100-1 Pouch Film 101 Inner layer 102 Metal layer 103 Outer layer 110 Cup section 111 Cup side 120 Seal part 121 Outer seal part 122 Additional seal part 130 Bridge section

Claims

1. (a) forming a pouch film including a metal layer so that a pair of cup portions capable of accommodating an electrode assembly are formed on both sides of a bridge portion in the pouch film; In the step (a), A method for manufacturing a pouch cell, wherein the pouch film is molded to satisfy the formula T / D>0.006, where T mm is the thickness of the metal layer of the bridge portion after molding, and D mm is the depth of the cup portion.

2. In the step (a), 2. The method for manufacturing a pouch cell according to claim 1, wherein the metal layer is shaped so that after shaping, the thickness of the metal layer in the bridge portion is 0.8 times or more the thickness of the metal layer before shaping.

3. (b) placing an electrode assembly in the cup portions and folding the pouch film based on the bridge portions so that the pair of cup portions cover the electrode assembly; (c) sealing the outer edge of the pouch film in a folded state; In the step (c), The method for producing a pouch cell according to claim 1 or 2, wherein the sealing is performed so that the shortest linear distance between the sealed portion and the cup portion is 0.5 mm or more and 1.5 mm or less.

4. (b) placing an electrode assembly in the cup portions and folding the pouch film based on the bridge portions so that the pair of cup portions cover the electrode assembly; (c) sealing the open portion of the pouch film in the folded state; The step (c) (c-1) sealing the outer edge of the pouch film; (c-2) forming an additional seal portion with a gap between the additional seal portion and the cup portion of 0.5 mm or more and 1.5 mm or less.

5. (a) forming a pouch film including a metal layer such that a pair of cup portions capable of accommodating an electrode assembly are formed on both sides of a bridge portion in the pouch film; In the step (a), A method for manufacturing a pouch cell, wherein the metal layer is shaped so that the thickness of the metal layer at the bridge portion is reduced by 20% or less.

6. The metal layer is The method for producing a pouch cell according to claim 5, wherein the pouch cell contains aluminum (Al).

7. an electrode assembly; a pouch including a metal layer and folded at both sides based on a bridge portion so as to cover the electrode assembly; The pouch comprises: a cup portion having a space therein for receiving the electrode assembly, A pouch cell that satisfies the formula T / D>0.006, where T mm is the thickness of the metal layer of the bridge portion and D mm is the depth of the cup portion.

8. The pouch comprises: a sealing portion disposed apart from the cup portion and sealing the electrode assembly to isolate it from the outside; The pouch cell according to claim 7 , wherein the shortest distance between the cup portion and the seal portion is 0.5 mm or more and 1.5 mm or less.

9. The sealing portion is an outer seal portion disposed at a predetermined distance from the cup portion; an additional seal portion disposed between the outer seal portion and the cup portion; The pouch cell according to claim 8 , wherein the distance between the additional seal portion and the cup portion is 0.5 mm or more and 1.5 mm or less.

10. The bridge portion is formed at one end of the cup portion, The additional seal portion is The pouch cell according to claim 9 , wherein one end is arranged to be in line with one end of the cup portion.

11. The additional seal portion is The pouch cell according to claim 9 , wherein the pouch cell has a shape in which the width gradually decreases from the outer seal portion toward the cup portion.

12. The pouch comprises: The pouch cell according to claim 8 , wherein the thickness of the metal layer of the bridge portion is 0.8 times or more the thickness of the metal layer of the seal portion.

Images