Secondary battery and method for manufacturing secondary battery

Abstract

A method for manufacturing a secondary battery, according to the present invention, includes: a preparation step of preparing an electrode assembly and an exterior material sheet having a plurality of wing parts; a packaging step of wrapping the electrode assembly with the exterior material sheet so as to form an inner space which accommodates the electrode assembly and exterior material openings which communicate the inner space with the outside; a cover member insertion step of inserting cover members into the exterior material openings; a folding step of folding the plurality of wing parts such that the plurality of wing parts come into contact with external surfaces, the outward-facing surfaces of the cover members; and a sealing step of sealing the inner space by coupling the plurality of wing parts and the external surfaces of the cover members.

Description

Secondary battery and secondary battery manufacturing method

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0147134, filed October 30, 2023, and Korean Patent Application No. 10-2024-0149725, filed October 29, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a rechargeable secondary battery and a method for manufacturing such a secondary battery.

[0005] Unlike primary batteries, which are non-rechargeable, secondary batteries (rechargeable batteries) are rechargeable and dischargeable. Small secondary batteries are used in portable electronic devices such as cell phones, laptops, and camcorders, while medium- or large-sized secondary batteries are widely used as power sources for motors in hybrid vehicles and other vehicles.

[0006] These secondary batteries can be classified into various types depending on the type of outer packaging material that accommodates the electrode assembly. For example, the secondary batteries can be classified into square secondary batteries in which the electrode assembly is accommodated inside a square metal can, cylindrical secondary batteries in which the electrode assembly is accommodated inside a cylindrical metal can, and pouch-type secondary batteries in which the electrode assembly is accommodated inside a pouch made of a laminate sheet.

[0007] Meanwhile, a pouch-type secondary battery can be manufactured by accommodating an electrode assembly in a cup portion within a pouch and then sealing the pouch. However, the molding depth of the cup portion is limited depending on the material properties of the pouch, and there was a problem in that the cup portion could not be molded deep enough to increase the capacity of the secondary battery.

[0008] To solve this problem, a pouch-type secondary battery was manufactured by, in the past, mounting an electrode assembly on a pouch-type outer material, folding or rolling the outer material to form an internal space for accommodating the electrode assembly, inserting a cover member into an open area communicating with the internal space, and then sealing the outer material and the cover member.

[0009] Fig. 1 is a drawing showing an example of a conventional pouch-type secondary battery, and Fig. 1 is a drawing schematically showing a front view of a conventional pouch-type secondary battery. The pouch-type secondary battery (1) includes a pouch-type outer case (3) that accommodates an electrode assembly therein, and a cover member (2) that is inserted into an open area of ​​the outer case (3) and is combined with an inner surface of the outer case (3) to seal the inner space of the outer case (3). The outer case (3) is composed of a metal substrate layer and a resin layer formed on both surfaces of the metal substrate layer, and the cover member (2) can be heat-sealed with an inner resin layer formed on the inner surface of the outer case (3) to seal the inner space of the outer case (3).

[0010] Meanwhile, Fig. 2 is a drawing showing an example of a sealing system for sealing the pouch-type secondary battery of Fig. 1. In order to thermally fuse the outer covering material (3) and the cover member (2), a process of pressing the cover member (2) and the outer covering material (3) with a high-temperature sealing block (4) must be followed. Specifically, when the high-temperature sealing block (4) presses the upper surface (1a) and the lower surface (1b) of the secondary battery (1), the outer covering material (3) can be thermally fused to the upper surface and the lower surface of the cover member (2), respectively. In addition, when the high-temperature sealing block (4) presses the left and right sides (1c, 1d) of the secondary battery (1), the outer covering material (3) can be thermally fused to the left and right sides of the cover member (2), respectively.

[0011] However, when heat-sealing the cover member (2) and the exterior material (3) in this manner, the process of pressing the cover member (2) and the exterior material (3) with the sealing block (4) is performed in two steps, which causes a problem in that the sealing efficiency of the cover member (2) and the exterior material (3) is reduced. In addition, the pressing force by the sealing member is not effectively transmitted to the corners of the cover member (2), which causes a problem in that the bonding performance of the cover member (2) and the exterior material (3) is reduced, resulting in a problem in that the internal space of the exterior material (3) is not sealed.

[0012] The present invention has been conceived in recognition of the above problems, and an object of the present invention is to provide a secondary battery capable of quickly sealing a cover member and an outer material and improving the bonding performance of the cover member and the outer material, and a method for manufacturing such a secondary battery.

[0013] A secondary battery according to the present invention comprises: an electrode assembly; a pouch-shaped outer material having an internal space for accommodating the electrode assembly and an outer material opening for communicating the internal space with the outside; and a cover member inserted into the outer material opening, wherein the outer material includes a plurality of wing portions folded to meet an outer surface of the cover member facing the outside, and the plurality of wing portions are combined with the outer surface of the cover member to seal the internal space.

[0014] The above-mentioned exterior material can be formed by rolling or folding the exterior material sheet so that one end and the other end of the exterior material sheet, which includes a metal layer and a resin layer formed on both sides of the metal layer, meet each other.

[0015] One end and the other end of the above outer sheet can be bonded or fused to each other.

[0016] Each of the above plurality of wing sections may have a trapezoidal or rectangular shape.

[0017] The above plurality of wing portions can be combined with the outer surface of the cover member in an overlapping state.

[0018] The overlapping portions of the above plurality of wing sections can be bonded or fused to each other.

[0019] The above plurality of wing portions can be bonded to the outer surface of the cover member by adhesion or fusion.

[0020] A guide line that guides the folding of the wing portion may be formed on the inner surface of the above outer material.

[0021] The above guide line may be a groove formed on the inner surface of the outer material.

[0022] The above cover member has a through hole formed into which an electrode lead is inserted, and the plurality of wing portions may not overlap the through hole.

[0023] A method for manufacturing a secondary battery according to the present invention may include a preparation step of preparing an electrode assembly and an outer sheet having a plurality of wing portions formed thereon; a packaging step of wrapping the electrode assembly with the outer sheet so as to form an internal space in which the electrode assembly is accommodated and an outer sheet opening communicating the internal space with the outside; a cover member insertion step of inserting a cover member into the outer sheet opening; a folding step of folding the plurality of wing portions so that the plurality of wing portions meet an outer surface of the cover member facing the outside; and a sealing step of sealing the internal space by combining the plurality of wing portions and the outer surface of the cover member.

[0024] The above preparation step may include a wing part forming step of cutting the exterior material sheet and forming a plurality of wing parts on the exterior material sheet.

[0025] The above wing portion forming step may include a step of forming a plurality of trapezoidal wing portions by forming a triangular or trapezoidal notch portion in the outer material sheet.

[0026] The packaging step may include a mounting step of positioning the electrode assembly on the upper surface of the outer sheet; a winding step of wrapping the electrode assembly by rolling or folding the outer sheet so that one end and the other end of the outer sheet meet each other; and a bonding step of bonding or fusing one end and the other end of the outer sheet.

[0027] The above folding step may include a step of sequentially folding the plurality of wing portions so that the plurality of wing portions are folded in a state where they overlap each other.

[0028] The sealing step may include a step of applying heat and pressure to the cover member and the plurality of wing parts so that the plurality of wing parts are fused to the outer surface of the cover member in an overlapping state.

[0029] The secondary battery manufacturing method according to the present invention may further include a guide line forming step, which is performed between the preparation step and the packaging step, of forming a guide line to guide folding of the wing portion by digging a groove in the inner surface of the outer sheet.

[0030] In the secondary battery according to the present invention, a pouch-shaped outer casing includes a plurality of wing portions that are bonded to the outer surface of a cover member to seal the inner space of the cover member, thereby enabling the outer casing and the cover member to be quickly sealed, and improving the bonding performance of the outer casing and the cover member to effectively seal the inner space of the outer casing.

[0031] A method for manufacturing a secondary battery according to the present invention comprises: a plurality of wing portions included in a pouch-shaped outer casing are bonded to the outer surface of a cover member to seal the inner space of the cover member; thus, the outer casing and the cover member can be quickly sealed; and the bonding performance of the outer casing and the cover member can be improved to effectively seal the inner space of the outer casing.

[0032] Figure 1 is a drawing showing an example of a pouch-type secondary battery.

[0033] FIG. 2 is a drawing showing an example of a sealing system for sealing the pouch-type secondary battery of FIG. 1.

[0034] Figure 3 is a perspective view of a secondary battery according to the present invention.

[0035] Figure 4 is an exploded perspective view of a secondary battery according to the present invention.

[0036] FIG. 5 is a drawing showing a secondary battery according to the present invention in which a plurality of wing parts are connected to a cover member while overlapping each other.

[0037] Figure 6 is a development diagram of an outer material for specifically explaining the shape of a guide line in a secondary battery according to the present invention.

[0038] FIG. 7 is a drawing showing a sealing area formed in a wing portion and a cover member in a secondary battery according to the present invention.

[0039] Figure 8 is a drawing explaining the shape of the wing portion having a rectangular shape in a secondary battery according to the present invention.

[0040] Figure 9 is a drawing explaining the process of combining a wing portion and a cover member in a secondary battery according to the present invention.

[0041] Figure 10 is a drawing for explaining a comparative example in which the wings of a secondary battery do not overlap.

[0042] Figure 11 is a flowchart showing a method for manufacturing a secondary battery according to the present invention.

[0043] Figure 12 is a flowchart showing the packaging step in the secondary battery manufacturing method according to the present invention.

[0044] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0045] In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components of each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification.

[0046] In addition, terms and words used in this specification and claims 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.

[0047] Hereinafter, a secondary battery and a method for manufacturing a secondary battery according to the present invention will be described with reference to the drawings.

[0048]

[0049] secondary battery

[0050] Fig. 3 is a perspective view of a secondary battery (10) according to the present invention, and Fig. 4 is an exploded perspective view of the secondary battery (10) according to the present invention. Fig. 5 is a drawing showing a state in which a plurality of wing parts (240) are connected to a cover member (300) in an overlapping state.

[0051] Referring to FIGS. 3 to 5, a secondary battery (10) according to the present invention may include an electrode assembly (100); a pouch-shaped outer material (200) having an internal space (220) for accommodating the electrode assembly (100) and an outer material opening (210) for communicating the internal space (220) with the outside; and a cover member (300) inserted into the outer material opening (210). Here, the outer material (200) includes a plurality of wing portions (240) folded to meet an outer surface (310) facing the outside of the surface of the cover member (300), and the plurality of wing portions (240) may be combined with the outer surface (310) of the cover member (300) to seal the internal space (220).

[0052] The electrode assembly (100) is a laminate including an anode, a cathode, and a separator, and may have various structures. For example, the electrode assembly may be a stacked electrode assembly in which the anode, the cathode, and the separator are laminated in one direction, or a stack-folded electrode assembly in which the anode, the cathode, and the separator are laminated in one direction and then folded.

[0053] Here, the positive electrode may include a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector, and the negative electrode may include a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector. The separator is a membrane of an insulating material interposed between the positive electrode and the negative electrode to block contact between the positive electrode and the negative electrode, and a plurality of pores through which positive ions pass may be formed in the separator.

[0054] The outer material (200) is formed by winding an outer material sheet (200a) in one direction, and an internal space (220) for accommodating an electrode assembly (100) can be formed inside the wound outer material sheet (200a). In addition, both sides of the internal space (220) can be connected to the outside.

[0055] Specifically, the exterior sheet (200a) is a sheet having one end (201a) and another end (202a) spaced apart from the one end (201a) in a predetermined direction, and the exterior sheet (200) can be formed by rolling or folding the exterior sheet (200a) so that the one end (201a) and the other end (202a) meet. The one end (201a) and the other end (202a) of the exterior sheet (200a) can be joined to each other in various ways. For example, the one end (201a) and the other end (202a) can be bonded to each other with an adhesive, or the one end (201a) and the other end (202a) can be heat-fused to each other by receiving heat and pressure.

[0056] One end (201a) of the exterior sheet (200a) can be joined to the inner surface or outer surface of the other end (202a). As illustrated in FIG. 4, the outer surface of one end (201a) of the exterior sheet (200a) can be joined to the inner surface of the other end (202a). Additionally, the inner surface of one end (201a) of the exterior sheet (200a) can also be joined to the inner surface of the other end (202a).

[0057] Meanwhile, the exterior sheet (200a) may be a laminate sheet including a metal layer such as aluminum or stainless steel. At this time, a resin layer may be formed on each of the outer and inner surfaces of the metal layer.

[0058] The metal layer can serve as a substrate that maintains mechanical strength and a barrier layer that prevents the infiltration of moisture and oxygen. In addition to preventing the inflow or leakage of foreign substances such as gas and moisture, the metal layer can be composed of aluminum or an aluminum alloy to enhance the strength of the battery case. Examples of aluminum alloys that can be used include alloy numbers 8079, 1N30, 8021, 3003, 3004, 3005, 3104, and 3105, and these can be used alone or in combination.

[0059] The first resin layer coated on the outer surface of the metal layer must have excellent resistance to the external environment in order to protect the electrode assembly from the outside. Therefore, the first resin layer is required to have excellent tensile strength and corrosion resistance relative to its thickness. For the first resin layer, a polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), a polyolefin resin such as polyethylene or polypropylene, etc. can be used.

[0060] The second resin layer coated on the inner surface of the metal layer can be combined with a cover member (300) described later to seal the internal space (220), and the second resin layer can be composed of a polyolefin series resin. For example, CPP (Casted Polypropylene), chlorinated polypropylene, polyethylene, ethylene propylene copolymer, polyethylene and acrylic acid copolymer, and polypropylene and acrylic acid copolymer can be used for the second resin layer.

[0061] Conventionally, a pouch-type secondary battery has been manufactured by forming a cup portion on a pouch film, inserting an electrode assembly into the cup portion, and then sealing the pouch film with the formed cup portion with another pouch film. However, due to the material properties of the pouch film, there was a limit to the forming depth of the cup portion, making it impossible to form the cup portion deeply to increase the capacity of the secondary battery. Furthermore, during the forming process of the cup portion, the thickness of the pouch film was reduced, which caused problems such as cracks to occur in the pouch film.

[0062] On the other hand, since the outer shell (200) of the secondary battery (10) according to the present invention is prepared by rolling or folding the outer shell sheet (200a), the electrode assembly (100) can be accommodated in the inner space (220) of the outer shell (200) without a separate cup portion forming. In this case, since the conventional limitation due to the formation of the cup portion in the outer shell is not applied, the capacity of the secondary battery (10) can be easily increased by increasing the size of the inner space (220). In addition, since the outer shell (200) prepared by rolling or folding the outer shell sheet (200a) does not have a portion where the thickness is reduced, the occurrence of defects such as cracks in the outer shell (200) can be prevented.

[0063] For reference, the secondary battery (10) according to the present invention can be formed by placing the electrode assembly (100) on the upper surface of the outer sheet (200a) in an unfolded state, and then rolling or folding the outer sheet (200a). In addition, the secondary battery (10) according to the present invention can be formed by rolling or folding the outer sheet (200a) to form an internal space (220) and an outer opening (210), and then inserting the electrode assembly (100) into the outer opening (210). In both of the above cases, the electrode assembly (100) can be accommodated inside the outer sheet (200) without forming a separate cup portion.

[0064] Meanwhile, referring to FIGS. 3 to 5, the cover member (300) may be a member that is coupled to the outer material (200) and blocks the outer material opening (210). The inner space (220) of the outer material (200) in which the electrode assembly (100) is accommodated may be filled with an electrolyte, and the cover member (300) may seal the inner space (220) to prevent the electrolyte from leaking from the inner space (220). Specifically, the cover member (300) inserted into the outer material opening (210) that connects the inner space (220) and the outside may be coupled with a wing portion (240) of the outer material (200) described below to seal the inner space (220).

[0065] The cover member (300) may be formed of a material that is not easily permeable to moisture in order to seal the internal space (220) of the exterior material (200) by being combined with the wing portion (240) of the exterior material (200). For example, the cover member (300) may be obtained from metal or resin, or may be obtained from a laminate sheet in which a resin layer is formed on both sides of a metal layer.

[0066] In addition, the cover member (300) may have various shapes. For example, the cover member (300) may be composed of a body (300a) and a gasket (300b) and may block the internal space (220) of the outer shell (200). Specifically, a through hole through which a gas lead (120) passes may be formed in the body (300a). The gasket (300b) is a member that surrounds the body (300a) and may prevent electrolyte leakage between the outer shell (200) and the body (300a). In this case, the gasket (300b) may also serve as a medium for a firm bond between the outer shell (200) and the body (300a).

[0067] The gasket (300b) may have various shapes. For example, the gasket (300b) may have a frame shape that surrounds a side surface of the outer surface of the body (300a). Additionally, the gasket (300b) may be formed to surround both the inner and outer surfaces of the body (300a).

[0068] At this time, the outer surface (310) of the cover member (300) facing the outside can be combined with the wing portion (240) of the exterior material (200) to seal the internal space (220) of the exterior material (200). The outer surface (310) of the cover member (300) can be the outer surface of the cover member (300) to which the body (300a) and the gasket (300b) are combined.

[0069] In this way, when the wing portion (240) of the outer material (200) is bonded to the outer surface (310) of the cover member (300) to seal the inner space (220), only one sealing surface for sealing the inner space (220) is formed between the wing portion (240) and the cover member (300), so that the secondary battery (10) can be quickly sealed. In addition, the wing portion (240) is only bonded to the outer surface (310) of the cover member (300) and is not bonded to the corner of the cover member (300), so that the wing portion (240) can be firmly bonded to the cover member (300) to effectively seal the inner space (220) of the outer material (200).

[0070] Meanwhile, as illustrated in FIGS. 3 to 5, a through hole may be formed in the cover member (300) into which an electrode lead (120) electrically connected to the electrode assembly (100) is inserted. The electrode lead (120) is connected to an electrode tab (110) connected to each electrode non-conductive portion of the electrodes stacked on the electrode assembly (100), and a portion of the electrode lead (120) may be exposed to the outside of the secondary battery (10). Here, the through hole may have a shape corresponding to the shape of the electrode lead (120) into which it is inserted.

[0071] The electrode lead (120) is configured to electrically connect the electrode assembly (100) to another device and may have various shapes. For example, the electrode lead (120) is provided to penetrate the body (300a) of the cover member (300) and may be formed in an I-shape so as not to be easily detached from the body (300a). In addition, electrode tabs (110) may be coupled to one surface of the electrode lead (120).

[0072] Additionally, a sealing member such as an O-ring may be interposed between the through hole and the electrode lead (120), or a sealant layer made of thermoplastic resin may be formed. In this case, the electrolyte injected into the internal space (220) can be prevented from leaking through the through hole.

[0073] Meanwhile, an electrolyte injection port may be formed in the cover member (300) for injecting an electrolyte into the internal space (220) of the outer material (200) containing the electrode assembly (100). The electrolyte injection port may be a through hole penetrating the cover member (300).

[0074] An electrolyte injection process can be performed to inject electrolyte into the internal space (220) through the electrolyte injection port. For example, a user can place the secondary battery (10) so that the cover member (300) in which the electrolyte injection port is formed faces upward, and then inject the electrolyte into the internal space (220) of the outer material (200) through the electrolyte injection port.

[0075] Additionally, a degassing process can be performed through the electrolyte inlet to discharge gases generated during activation of the secondary battery (10) to the outside. For example, a user can open the electrolyte inlet to induce the discharge of gases in the internal space (220).

[0076] After the electrolyte injection process or degassing process, the electrolyte injection port can be sealed or welded to seal the internal space (220). In addition, it is also possible to install an openable valve in the electrolyte injection port so that the electrolyte injection port can be opened only when necessary.

[0077] Meanwhile, conventional pouch-type secondary batteries have a gas pocket formed by rolling up a portion of the outer material, and the gas pocket is removed from the outer material after capturing the internal gas of the outer material. Therefore, there has been a problem in the past of repeatedly discarding a portion of the outer material. In this regard, the secondary battery (10) according to the present invention includes an electrolyte injection port formed in a cover member (300), and a user can inject electrolyte into the internal space (220) and discharge gas from the internal space (220) to the outside through the electrolyte injection port, thereby solving the conventional problem of repeatedly discarding a portion of the outer material.

[0078] In addition, the portion of the cover member (300) where the electrolyte injection port and the through hole are formed may not overlap with the plurality of wing parts (240). Specifically, the plurality of wing parts (240) are coupled to a portion of the outer surface of the cover member (300), and the electrolyte injection port and the through hole may be formed in the central portion of the cover member (300) where the wing parts (240) are not coupled.

[0079] Accordingly, the plurality of wing parts (240) do not interfere with the electrode lead (120) passing through the through hole. In addition, even when electrolyte is injected or internal gas is discharged through the electrolyte injection port, the plurality of wing parts (240) do not provide any interference.

[0080] Meanwhile, as illustrated in FIGS. 3 to 5, the exterior material (200) may include wing portions (240) formed by cutting a portion of the exterior material sheet (200a). A plurality of wing portions (240) may be formed on the exterior material (200), and the plurality of wing portions (240) may be combined with the outer surface (310) of the cover member (300) to seal the internal space (220).

[0081] The wing portion (240) may have various shapes. The wing portion (240) may have a rectangular shape, and as illustrated in FIG. 4, the wing portion (240) may have a trapezoidal shape.

[0082] Each of the plurality of wing portions (240) can be thermally bonded to the outer surface (310) of the cover member (300). Specifically, the cover member (300) and the wing portions (240) can be thermally bonded to each other by being pressed by a sealing block at a high temperature or by receiving heat and pressure simultaneously from the sealing block. At this time, the sealing block can pressurize the portion where the flat outer surface (310) of the cover member (300) and the wing portions (240) meet to thermally bond the wing portions (240) and the outer surface (310).

[0083] Here, since the sealing block does not have a protruding or dug-out portion on the pressing surface that presses the wing portion (240) and the outer surface (310), the sealing block can uniformly press the wing portion (240) and the outer surface (310). In this case, the wing portion (240) can be uniformly heat-sealed to the outer surface (310) of the cover member (300) to form a sealing portion that seals the inner space (220) of the outer material (200). The cover member (300) can be composed of a body (300a) and a gasket (300b), and the wing portion (240) can be heat-sealed to the outer surface of the body (300a) and the gasket (300b) to seal the interior.

[0084] Meanwhile, each of the plurality of wing parts (240) may be bonded to the outer surface (310) of the cover member (300) in an adhesive manner. Specifically, an adhesive layer using an adhesive tape or a cured adhesive may be formed between the wing parts (240) and the outer surface (310) of the cover member (300), and this may become a sealing part that seals the inner space (220) of the outer material (200).

[0085] In addition, the overlapping portion (a) where the plurality of wing portions (240) overlap each other can be bonded or fused to each other. Specifically, an adhesive layer using an adhesive tape or a cured adhesive can be formed on the overlapping portion (a) where the plurality of wing portions (240) overlap each other. In addition, the overlapping portions (a) can be pressurized with a sealing block to be heat-fused to each other.

[0086] In this way, when a plurality of wing parts (240) are combined in an overlapping portion (a) that overlaps each other, the secondary battery (10) has a first bonding layer formed between the plurality of wing parts (240) and the cover member (300) and a second bonding layer formed in the overlapping portion (a), so that the internal space (220) of the outer material (200) can be effectively sealed.

[0087] Meanwhile, Fig. 6 is a development view of the exterior material (200), and is a drawing for explaining the shape of the guide line (231) formed on the inner surface (230) of the exterior material (200). Referring to Fig. 6, a guide line (231) that guides the folding of the wing part (240) may be formed on the inner surface (230) of the exterior material (200). Specifically, the guide line (231) may be formed on the inner portion of the wing part (240) among the inner surface (230) of the exterior material (200). After the exterior material (200) is rolled or folded to form the inner space (220) and the exterior material opening (210), the wing part (240) may be folded into the inner space (220) along the guide line (231) formed on the inner surface (230) of the exterior material (200).

[0088] At this time, the guide line (231) may be a groove formed on the inner surface (230) of the outer material (200). In this case, the portion of the outer material (200) where the guide line (231) is formed has a thinner thickness than the surrounding area, and can be folded or bent with relatively little force.

[0089] A plurality of notched portions (b) may be formed in the outer casing (200) to distinguish the wing portions (240). That is, a notched portion (b) in which a portion of the outer casing (200) is notched may be formed between the wing portions (240). The notched portion (b) may be formed to various depths. For example, the notched portion (b) may be formed between one end of the outer casing sheet and the guide line (231).

[0090] Additionally, the notched portion (b) may have various shapes. For example, as illustrated in FIG. 6, the notched portion (b) may be a region in which the exterior material (200) is cut into a triangular shape. Additionally, the notched portion (b) may be formed by cutting the exterior material (200) into a trapezoidal shape.

[0091] Fig. 7 is a drawing showing a sealing area (400) formed in a wing portion (240) and a cover member (300). Referring to Fig. 7, a sealing area (400) in a square ring shape can be formed between the wing portion (240) and the cover member (300). The sealing area (400) is a closed loop area formed by pressurizing the wing portion (240) and the cover member (300) by a pressurizing member (500) described later, and can seal the internal space (220) of the exterior material (200) from the outside.

[0092] Specifically, the outer surface (310) of the wing portion (240) and the cover member (300) can be heat-sealed to each other along the closed-loop shaped sealing area (400) to seal the internal space (220). In addition, the portions of the overlapping portions of the wing portions (240) that are included in the sealing area (400) can be heat-sealed to each other. That is, the portion of the overlapping portion (a) of the wing portions (240) that is included in the sealing area (400) can be heat-sealed.

[0093] Fig. 8 is a drawing illustrating a secondary battery according to the present invention in which wing portions have a rectangular shape. Referring to Fig. 8, each of the plurality of wing portions (240) has a rectangular shape, and the overlapping portion (a) where these wing portions (240) overlap each other may also have a rectangular shape.

[0094] Meanwhile, the gap between the wing portions (240) having a trapezoidal or rectangular shape can be formed relatively narrow. Accordingly, these wing portions (240) can cover most of the edge of the outer surface (310) of the cover member (300), and thus the secondary battery (10) can have a high sealing force. In addition, although not shown in FIGS. 7 and 8, a plurality of wing portions (240) can be combined up to the corner portion of the outer surface (310) to seal the entire edge portion of the outer surface (310).

[0095] Fig. 9 is a drawing explaining a process of joining a wing portion (240) and a cover member (300). Referring to Fig. 9, the wing portion (240) can be pressed by a pressing member (500) while folded toward the cover member (300). The pressing member (500) can pressurize the wing portion (240) and the cover member (300) at high temperatures to fuse the wing portion (240) and the cover member (300).

[0096] Additionally, a heating element such as a heating wire may be installed in the pressurizing member (500). In this case, the pressurizing member (500) can simultaneously apply heat and pressure to the wing portion (240) and the cover member (300) to fuse the wing portion (240) and the cover member (300).

[0097] Meanwhile, Fig. 10 is a drawing for explaining a comparative example in which the wing parts of the secondary battery do not overlap. Fig. 10 illustrates a state in which the wing parts (240') of the secondary battery do not overlap each other. At this time, the front surfaces of the wing parts (240') of the secondary battery may all be attached to the outer surface (310') of the cover member. In addition, the through-hole (320') through which the electrode lead passes and the electrolyte injection hole through which the electrolyte is injected may not overlap with a plurality of wing parts (240').

[0098] In this case, when the wing parts (240') do not overlap each other, the wing parts (240') are all attached only to the outer surface (310') of the cover member, and thus the wing parts (240') cannot effectively seal the internal space of the secondary battery. Therefore, when the internal pressure increases as the secondary battery is repeatedly charged and discharged, the bond between the wing parts (240') and the outer surface (310') may be released.

[0099] Unlike the comparative example illustrated in FIG. 10, the secondary battery (10) according to the present invention has a first bonding layer formed between a plurality of wing parts (240) and a cover member (300) and a second bonding layer formed in the overlapping part (a), so that the internal space (220) of the outer material (200) can be effectively sealed.

[0100]

[0101] Secondary battery manufacturing method

[0102] Figure 11 is a flowchart showing a method for manufacturing a secondary battery according to the present invention. The method for manufacturing a secondary battery according to the present invention comprises: a preparation step (S100) of preparing an electrode assembly (100) and an outer sheet (200a) having a plurality of wing parts (240) formed thereon; a packaging step (S300) of wrapping the electrode assembly (100) with an outer sheet (200a) so as to form an internal space (220) in which the electrode assembly (100) is accommodated and an outer opening (210) connecting the internal space (220) with the outside; a cover member insertion step (S400) of inserting a cover member (300) into the outer opening (210); a folding step (S500) of folding the plurality of wing parts (240) so that the plurality of wing parts (240) meet an outer surface (310) of the surface of the cover member (300) facing the outside; And it may include a sealing step (S600) of sealing the internal space (220) by combining the outer surface (310) of the plurality of wing parts (240) and the cover member (300).

[0103] In this way, when the wing portion (240) of the outer material (200) is bonded to the outer surface (310) of the cover member (300) to seal the inner space (220), only one sealing surface for sealing the inner space (220) is formed between the wing portion (240) and the cover member (300), so that the secondary battery (10) can be quickly sealed. In addition, the wing portion (240) is only bonded to the outer surface (310) of the cover member (300) and is not bonded to the corner of the cover member (300), so that the wing portion (240) can be firmly bonded to the cover member (300) to effectively seal the inner space (220) of the outer material (200).

[0104] The preparation step (S100) is a step of preparing an electrode assembly (100) and an outer sheet (200a) having a plurality of wing parts (240) formed thereon, and may include a wing part forming step of cutting the outer sheet (200a) to form a plurality of wing parts (240) on the outer sheet (200a). At this time, the wing part forming step may be a step of forming a triangular or trapezoidal notch (b) on the outer sheet (200a) to form a plurality of trapezoidal wing parts (240).

[0105] Here, the notched portion (b) can be formed by cutting the exterior material sheet (200a). Specifically, the notched portion (b) can be formed between one end of the exterior material sheet and the guide line (231). When a plurality of notched portions (b) are formed at one end of the exterior material sheet (200a), an uncut portion of the exterior material sheet (200a) is located between the plurality of notched portions (b), and the portion can become a wing portion (240).

[0106] Figure 12 is a flowchart showing a packaging step in a secondary battery manufacturing method according to the present invention. The packaging step (S300) may include a mounting step (S310) of positioning the electrode assembly (100) on the upper surface of the outer sheet (200a); a winding step (S320) of wrapping the electrode assembly (100) by rolling or folding the outer sheet (200a) so that one end (201a) and the other end (202a) of the outer sheet (200a) meet each other; and a bonding step (S330) of bonding or fusing one end (201a) and the other end (202a) of the outer sheet (200a).

[0107] Conventionally, a pouch-type secondary battery has been manufactured by forming a cup portion on a pouch film, inserting an electrode assembly into the cup portion, and then sealing the pouch film with the formed cup portion with another pouch film. However, due to the material properties of the pouch film, there was a limit to the forming depth of the cup portion, making it impossible to form the cup portion deeply to increase the capacity of the secondary battery. Furthermore, during the forming process of the cup portion, the thickness of the pouch film was reduced, which caused problems such as cracks to occur in the pouch film.

[0108] On the other hand, in the case of the secondary battery manufacturing method according to the present invention, the electrode assembly (100) is wrapped by rolling or folding the outer material sheet (200a), so that the electrode assembly (100) can be accommodated inside the outer material (200) without a separate cup part forming. In this case, since the conventional limitation due to the formation of the cup part in the outer material is not applied, the capacity of the secondary battery (10) can be easily increased. In addition, since the outer material (200) prepared by rolling or folding the outer material sheet (200a) does not have a portion where the thickness is reduced, the occurrence of defects such as cracks in the outer material (200) can be prevented.

[0109] For reference, the packaging step (S300) may be composed of a first step of rolling or folding the outer sheet (200a) so that one end (201a) and the other end (202a) of the outer sheet (200a) meet each other to form an internal space (220) and an outer opening (210), a second step of joining one end (201a) and the other end (202a) of the outer sheet (200a) by fusion or adhesive method, and a third step of inserting the electrode assembly (100) into the outer opening (210) to secure the electrode assembly (100) in the internal space (220). Even in this case, the electrode assembly (100) can be accommodated in the internal space (220) without forming a separate cup portion in the outer sheet (200).

[0110] Meanwhile, the folding step (S500) may be a step of sequentially folding the plurality of wing parts (240) so that the plurality of wing parts (240) are folded in a state where they overlap each other. In this case, a portion (a) where the plurality of wing parts (240) overlap each other may be formed on the outside of the outer surface (310) of the cover member (300).

[0111] The sealing step (S600) may include a step of applying heat and pressure to the cover member (300) and the plurality of wing parts (240) so that the plurality of wing parts (240) are fused with the outer surface (310) of the cover member (300) in an overlapping state. In this case, when the overlapping portion (a) where the plurality of wing parts (240) overlap each other is fused, the secondary battery (10) has a first bonding layer formed between the plurality of wing parts (240) and the cover member (300) and a second bonding layer formed in the overlapping portion (a), so that the internal space (220) of the outer material (200) can be effectively sealed.

[0112] Meanwhile, the secondary battery manufacturing method according to the present invention may include a guide line forming step (S200) performed between the preparation step (S100) and the packaging step (S300), in which a groove is dug into the inner surface (230) of the outer sheet (200a) to form a guide line (231) that guides the folding of the wing portion (240). In this case, the portion of the outer sheet (200) where the guide line (231) is formed has a thinner thickness than the surrounding area, and thus can be folded or bent with relatively little force.

[0113]

[0114] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various embodiments are possible within the scope equivalent to the technical idea of ​​the present invention and the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0115]

[0116] [Explanation of symbols]

[0117] 10: Secondary battery 100: Electrode assembly

[0118] 110: Electrode tab 120: Electrode lead

[0119] 200: Exterior material 200a: Exterior material sheet

[0120] 201a: Exterior sheet end 202a: Exterior sheet end

[0121] 210: Exterior opening 220: Interior space

[0122] 230: Inner surface of exterior material 231: Guide line

[0123] 240: Wing part 300: Cover part

[0124] 310: Outer surface of cover member 320: Through hole

[0125] 400: Sealing area 500: Pressurized member

[0126] S100: Preparation stage S200: Guideline formation stage

[0127] S300: Packaging stage S310: Settling stage

[0128] S320: Winding stage S330: Combination stage

[0129] S400: Cover member insertion step S500: Folding step

[0130] S600: Ceiling stage

Claims

1. Electrode assembly; A pouch-shaped outer material having an internal space for accommodating the electrode assembly and an outer material opening for communicating the internal space with the outside; and Including a cover member inserted into the above outer material opening, The above outer material includes a plurality of wing portions folded to meet the outer surface facing the outside of the surface of the cover member, A secondary battery in which the plurality of wing portions are combined with the outer surface of the cover member to seal the inner space.

2. In claim 1, The above exterior material is, A secondary battery characterized in that the outer sheet is formed by rolling or folding so that one end and the other end of the outer sheet, which includes a metal layer and a resin layer formed on both sides of the metal layer, meet each other.

3. In claim 2, A secondary battery characterized in that one end and the other end of the outer sheet are bonded or fused to each other.

4. In claim 1, A secondary battery characterized in that each of the plurality of wing sections has a trapezoidal or rectangular shape.

5. In claim 1, A secondary battery characterized in that the plurality of wing portions are combined with the outer surface of the cover member in an overlapping state.

6. In claim 5, A secondary battery characterized in that the overlapping portions of the plurality of wing sections are bonded or fused to each other.

7. In claim 5, A secondary battery characterized in that the plurality of wing portions are bonded to the outer surface of the cover member by adhesion or fusion.

8. In claim 1, A secondary battery characterized in that a guide line for guiding the folding of the wing portion is formed on the inner surface of the outer material.

9. In claim 8, A secondary battery characterized in that the above guide line is a groove formed on the inner surface of the outer material.

10. In claim 1, The above cover member has a through hole formed into which an electrode lead is inserted, A secondary battery characterized in that the plurality of wing portions do not overlap with the through hole.

11. A preparatory step of preparing an electrode assembly and an outer sheet having a plurality of wing parts formed thereon; A packaging step of wrapping the electrode assembly with the outer material sheet so that an internal space in which the electrode assembly is accommodated and an outer material opening connecting the internal space and the outside are formed; A cover member insertion step of inserting a cover member into the above outer material opening; A folding step of folding the plurality of wing portions so that the plurality of wing portions meet the outer surface of the surface of the cover member facing the outside; and A secondary battery manufacturing method including a sealing step of sealing the internal space by combining the outer surface of the plurality of wing parts and the cover member.

12. In claim 11, The above preparation steps are: A secondary battery manufacturing method characterized by including a wing part forming step of cutting the outer material sheet and forming a plurality of wing parts on the outer material sheet.

13. In claim 12, The above wing formation step is: A method for manufacturing a secondary battery, characterized by including a step of forming a triangular or trapezoidal notch portion on the outer sheet to form a plurality of trapezoidal wing portions.

14. In claim 11, The above packaging steps are: A mounting step of positioning the electrode assembly on the upper surface of the outer sheet; A winding step of wrapping the electrode assembly by rolling or folding the outer sheet so that one end and the other end of the outer sheet meet each other; and A secondary battery manufacturing method characterized by including a bonding step of bonding or fusing one end and the other end of the outer sheet.

15. In claim 11, The above folding step is, A method for manufacturing a secondary battery, characterized in that it includes a step of sequentially folding the plurality of wing portions so that the plurality of wing portions are folded in a state in which they overlap each other.

16. In claim 15, The above sealing step is, A secondary battery manufacturing method characterized by including a step of applying heat and pressure to the cover member and the plurality of wing parts so that the plurality of wing parts overlap each other and are fused to the outer surface of the cover member.

17. In claim 11, A secondary battery manufacturing method characterized in that it further includes a guide line forming step performed between the preparation step and the packaging step, wherein a groove is dug into the inner surface of the outer sheet to form a guide line that guides the folding of the wing portion.

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