Secondary battery and secondary battery manufacturing method

Abstract

The present invention relates to a secondary battery and a secondary battery manufacturing method, and, more particularly, to a secondary battery capable of repeated charging and discharging, and a manufacturing method therefor. The secondary battery according to one embodiment of the present invention may comprise: an electrode assembly; an exterior material having an inner space for accommodating the electrode assembly, and first and second exterior material openings by which the inner space communicates with the outside; a first cap for sealing the first exterior material opening; a second cap for sealing the second exterior material opening; and a cathode lead and an anode lead, which are connected to the electrode assembly and are at least partially exposed to the outside through the first cap. Here, the first cap and the second cap are coupled to the inner surface of the exterior material, and the coupling force between the first cap and the inner surface of the exterior material can be stronger than the coupling force between the second cap and the inner surface of the exterior material.

Description

Secondary battery and method for manufacturing a secondary battery

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0131778 filed September 27, 2024 and Korean Patent Application No. 10-2025-0132063 filed September 15, 2025, and all contents disclosed in the documents of said Korean patent applications are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present invention relates to a secondary battery and a method for manufacturing a secondary battery, and more specifically, to a secondary battery capable of repeated charging and discharging and a method for manufacturing the same.

[0005] Rechargeable secondary batteries can be classified into cylindrical, prismatic, and pouch types depending on their shape. Among these, pouch-type secondary batteries utilize a sheet-type outer casing composed of a multilayer film of a metal layer (foil) and resin layers coated on both sides of the metal layer; this allows for a significant reduction in battery weight compared to cylindrical or prismatic types that use metal cans.

[0006] The casing of such a pouch-type secondary battery may contain an electrolyte along with an electrode assembly. At this time, residual moisture in the electrolyte or moisture penetrating from the outside may react with the lithium salt inside the casing of the pouch-type secondary battery to generate HF (hydrogen fluoride), and gases such as carbon dioxide, carbon monoxide, ethylene, and methane may be generated due to the decomposition of the electrolyte.

[0007] In addition, depending on the material of the positive electrode included in the electrode assembly of the pouch-type secondary battery, additional hydrogen and HF may be generated, which can lead to overheating due to overcharging and internal short circuits during the charging and discharging process of the secondary battery. Consequently, a large amount of gas may be generated inside the outer casing.

[0008] Due to such gases, the internal pressure of the outer casing increases, and this elevated pressure can cause a venting phenomenon in which the casing bursts. In this case, if venting occurs in a portion of the outer casing adjacent to the electrode lead of a surrounding pouch-type secondary battery, there was a problem where the electrode lead was damaged. Therefore, there is a need for a structure that can induce venting in a specific direction away from the electrode lead of the secondary battery.

[0009] The present invention was devised in recognition of the above-mentioned problems, and the objective of the present invention is to provide a secondary battery capable of venting internal gas in a specific direction and a method for manufacturing such a secondary battery.

[0010] A secondary battery according to a first embodiment of the present invention comprises: an electrode assembly; an outer casing having an internal space accommodating the electrode assembly and first and second outer casing openings communicating the internal space with the outside; a first cap sealing the first outer casing opening; a second cap sealing the second outer casing opening; and a positive lead and a negative lead connected to the electrode assembly, with at least a portion penetrating the first cap and being exposed to the outside, wherein the first cap and the second cap are coupled to the inner surface of the outer casing, and the coupling force between the first cap and the inner surface of the outer casing may be stronger than the coupling force between the second cap and the inner surface of the outer casing.

[0011] The above exterior material may 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 resin layers formed on both sides of the metal layer, meet each other.

[0012] One end and the other end of the above exterior material sheet can be bonded or fused to each other.

[0013] The secondary battery according to the first embodiment of the present invention may further include a pressing member that presses the portion of the outer material coupled with the first cap toward the first cap side.

[0014] The above-mentioned pressure member may include a resin that has been cured on the outer surface of the portion of the exterior material combined with the first cap.

[0015] The first cap may include a body portion through which the positive lead and the negative lead pass; and a gasket formed on the outer surface of the body portion and coupled with the exterior material.

[0016] The thickness of the above gasket is 0.5 mm or more, and the above gasket may be made of PP material.

[0017] Meanwhile, a secondary battery according to a second embodiment of the present invention comprises: an electrode assembly; an outer material having an inner space accommodating the electrode assembly and an outer material opening communicating the inner space with the outside; a cap sealing the outer material opening; and a positive lead and a negative lead connected to the electrode assembly, with at least a portion penetrating the cap and being exposed to the outside, wherein only one outer material opening is formed in the outer material, and the cap may be coupled to the inner surface of the portion of the outer material where the outer material opening is formed.

[0018] The secondary battery according to the second embodiment of the present invention may further include a pressing member that presses the portion of the outer material coupled with the cap toward the cap side.

[0019] The above-mentioned pressure member may include a resin that has been cured on the outer surface of the portion of the exterior material combined with the cap.

[0020] Meanwhile, a method for manufacturing a secondary battery according to a first embodiment of the present invention comprises the steps of: combining a positive lead and a negative lead to an electrode assembly; wrapping the electrode assembly with a sheet-type outer material to form an internal space accommodating the electrode assembly and first and second outer material openings communicating the internal space with the outside; sealing the first outer material opening with a first cap; and sealing the second outer material opening with a second cap, wherein the positive lead and the negative lead penetrate the first cap and are exposed to the outside, and the sealing strength of the first cap sealing the first outer material opening may be stronger than the sealing strength of the second cap sealing the second outer material opening.

[0021] The step of sealing the first exterior material opening with a first cap may include the step of inserting the first cap into the first exterior material opening; and the step of heat-fusing the first cap to the inner surface of the exterior material.

[0022] In the step of heat-fusing the first cap to the inner surface of the outer surface material, the first cap and the inner surface of the outer surface material may be heated and pressurized for 3 to 10 seconds at a temperature range of 210 to 230°C.

[0023] The step of sealing the second exterior material opening with a second cap may include the step of inserting the second cap into the second exterior material opening; and the step of heat-fusing the second cap to the inner surface of the exterior material.

[0024] The step of sealing the first exterior material opening with a first cap and the step of sealing the second exterior material opening with a second cap may be performed simultaneously or sequentially.

[0025] The method for manufacturing a secondary battery according to the first embodiment of the present invention is performed after the step of sealing the opening of the second outer material with the second cap, and may further include the step of applying a curable resin to the outer surface of the portion of the outer material combined with the first cap.

[0026] Meanwhile, a method for manufacturing a secondary battery according to a second embodiment of the present invention comprises the steps of: combining a positive electrode lead and a negative electrode lead to an electrode assembly; wrapping the electrode assembly with a sheet-type outer material to form an internal space accommodating the electrode assembly and an outer material opening communicating the internal space with the outside; and sealing the outer material opening with a cap, wherein at least a portion of the positive electrode lead and the negative electrode lead penetrates the cap and is exposed to the outside, and only one outer material opening is formed in the outer material, and the cap may be coupled to the inner surface of the portion of the outer material where the outer material opening is formed.

[0027] The step of sealing the opening of the exterior material with a cap may include the step of inserting the cap into the opening of the exterior material; and the step of heat-fusing the cap to the inner surface of the exterior material.

[0028] In the step of heat-fusing the cap to the inner surface of the outer surface material, the cap and the inner surface of the outer surface material may be heated and pressurized for 3 to 10 seconds at a temperature range of 210 to 230°C.

[0029] The method for manufacturing a secondary battery according to the second embodiment of the present invention is performed after the step of sealing the opening of the outer material with a cap, and may further include the step of applying a curable resin to the outer surface of the portion of the outer material combined with the cap.

[0030] In a secondary battery according to one embodiment of the present invention, the bonding force between the inner surface of the first cap through which the positive lead and the negative lead pass and the outer surface of the outer surface is formed to be stronger than the bonding force between the inner surface of the second cap and the outer surface of the outer surface, thereby preventing venting to the side of the first cap through which the positive lead and the negative lead pass.

[0031] FIG. 1 is an exploded perspective view of a secondary battery according to a first embodiment of the present invention.

[0032] FIG. 2 is a plan view of a secondary battery according to a first embodiment of the present invention.

[0033] FIG. 3 is a perspective view showing a secondary battery with a pressurizing member coupled thereto according to a first embodiment of the present invention.

[0034] FIG. 4 is a cross-sectional view for explaining the structure of a first cap of a secondary battery according to a first embodiment of the present invention.

[0035] FIG. 5 is an exploded perspective view of a secondary battery according to a second embodiment of the present invention.

[0036] FIG. 6 is a perspective view showing a secondary battery with a pressurizing member coupled thereto according to a second embodiment of the present invention.

[0037] FIG. 7 is a cross-sectional view illustrating the cap structure of a secondary battery according to a second embodiment of the present invention.

[0038] FIG. 8 is a flowchart sequentially illustrating a method for manufacturing a secondary battery according to a first embodiment of the present invention.

[0039] FIG. 9 is a flowchart showing in detail the step of a first cap being coupled to an outer material in a method for manufacturing a secondary battery according to a first embodiment of the present invention.

[0040] FIG. 10 is a flowchart showing in detail the step of a second cap being coupled to an outer material in a method for manufacturing a secondary battery according to the first embodiment of the present invention.

[0041] FIG. 11 is a flowchart sequentially illustrating a method for manufacturing a secondary battery according to a second embodiment of the present invention.

[0042] Hereinafter, preferred embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in various different forms and is not limited or restricted by the following embodiments.

[0043] In order to clearly explain the present invention, detailed descriptions of related prior art that are irrelevant to the explanation or could unnecessarily obscure the essence of the invention have been omitted. Furthermore, when assigning reference numerals to the components of each drawing in this specification, identical or similar reference numerals are assigned to identical or similar components throughout the entire specification.

[0044] In addition, terms or words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0045] 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.

[0046] secondary battery

[0047] First embodiment

[0048] FIG. 1 is an exploded perspective view of a secondary battery according to a first embodiment of the present invention, and FIG. 2 is a plan view of a secondary battery according to a first embodiment of the present invention.

[0049] Referring to FIG. 1 and FIG. 2, a secondary battery (10) according to a first embodiment of the present invention may include an electrode assembly (100), an internal space (S) accommodating the electrode assembly (100), an exterior material (200) having first and second exterior material openings (210, 220) communicating with the outside of the internal space (S), a first cap (310) sealing the first exterior material opening (210), a second cap (320) sealing the second exterior material opening (220), and a positive lead (110) and a negative lead (120) connected to the electrode assembly (100) and exposed to the outside by penetrating the first cap (310). At this time, the first cap (310) and the second cap (320) are bonded to the inner surface of the exterior material (200), and the bonding force between the first cap (310) and the inner surface of the exterior material (200) may be stronger than the bonding force between the second cap (320) and the inner surface of the exterior material (200).

[0050] In this case, the bonding force between the inner surface of the first cap (310) through which the positive lead (110) and the negative lead (120) pass and the outer surface of the outer surface (200) is formed to be stronger than the bonding force between the inner surface of the second cap (320) located on the opposite side of the first cap (310) and the outer surface of the outer surface (200), so that when the internal pressure of the secondary battery (10) increases, the bond between the inner surface of the second cap (320) and the outer surface of the outer surface (200) can be preferentially released. That is, it is possible to prevent venting from occurring toward the side of the first cap (310) through which the positive lead (110) and the negative lead (120) pass, and thus, even if venting occurs in the secondary battery (10), damage to the positive lead (110) and the negative lead (120) can be prevented.

[0051] The secondary battery (10) may have a form in which an electrode assembly (100) is housed inside an outer casing (200). For example, the secondary battery (10) according to the present invention may refer to a pouch-type secondary battery among various forms of secondary batteries capable of charging and discharging. This is merely one example, and the shape of the secondary battery (10) may vary.

[0052] The electrode assembly (100) may include an anode, a cathode, and a separator. Here, the separator may be placed between the anode and the cathode to physically separate the anode and the cathode. The electrode assembly (100) may be in a stacked form in which the anode, the cathode, and the separator are stacked, or in a jelly-roll form in which the anode, the cathode, and the separator are wound.

[0053] The electrode assembly (100) may be provided with one or more positive and negative electrodes, and the positive electrode of the electrode assembly (100) may be connected to a positive lead (110), and the negative electrode of the electrode assembly (100) may be connected to a negative lead (120). At this time, the positive lead (110) and the negative lead (120) may be formed on one side of the electrode assembly (100). That is, the electrode assembly (100) may be a unidirectional cell in which the positive lead (110) and the negative lead (120) are formed in the same direction.

[0054] The exterior material (200) is formed by winding a sheet-shaped exterior material in one direction, and an internal space (S) for accommodating an electrode assembly (100) may be formed inside the wound exterior material sheet. Additionally, both sides of the internal space (S) may be in communication with the outside.

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

[0056] One end (201) of the exterior material sheet can be joined to the inner or outer surface of the other end (202). As shown in FIG. 1, the outer surface of one end (201) of the exterior material sheet can be joined to the inner surface of the other end (202). Additionally, the inner surface of one end (201) of the exterior material sheet can be joined to the inner surface of the other end (202).

[0057] Meanwhile, the exterior sheet may be a laminate sheet containing a metal layer such as aluminum or stainless steel. In this case, a resin layer may be formed on the outer and inner surfaces of the metal layer, respectively.

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

[0059] The first resin layer coated on the outer surface of the metal layer must have excellent resistance to the external environment to protect the electrode assembly from the outside; therefore, the first resin layer requires excellent tensile strength and corrosion resistance relative to its thickness. For such a first resin layer, polyester-based resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), and polyolefin-based resins such as polyethylene and polypropylene may be used.

[0060] The second resin layer coated on the inner surface of the metal layer can be combined with the first and second caps (310, 320) described later to seal the internal space (S), and the second resin layer may be composed of a polyolefin-based resin. For example, the second resin layer may use CPP (Casted Polypropylene), chlorinated polypropylene, polyethylene, ethylene-propylene copolymer, polyethylene-acrylic acid copolymer, and polypropylene-acrylic acid copolymer.

[0061] Conventionally, a pouch-type secondary battery was 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 characteristics of the pouch film, there was a limitation on the forming depth of the cup portion, making it impossible to form the cup portion deeply to increase the capacity of the secondary battery. In addition, there was a problem in that defects such as cracks occurred in the pouch film as the thickness of the pouch film became thin during the forming process of the cup portion.

[0062] On the other hand, the exterior material (200) of the secondary battery (10) according to the first embodiment of the present invention is formed by rolling or folding an exterior material sheet, so that the electrode assembly (100) can be accommodated in the internal space (S) of the exterior material (200) without the need for a separate cup portion molding. In this case, since the conventional limitation of forming a cup portion in the exterior material does not apply, the capacity of the secondary battery (10) can be easily increased by increasing the size of the internal space (S). Furthermore, since no portion with reduced thickness is formed in the exterior material (200) formed by rolling or folding an exterior material sheet, defects such as cracks can be prevented in the exterior material (200).

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

[0064] The first cap (310) and the second cap (320) may be members that are coupled to the outer material (200) and block the first and second outer material openings (210, 220). The internal space (S) of the outer material (200) in which the electrode assembly (100) is housed may be filled with an electrolyte, and the first and second caps (310, 320) may seal the internal space (S) to prevent the electrolyte from leaking out.

[0065] Specifically, the first cap (310) can be sealed by being coupled to the inner surface of the exterior material (200) after being inserted into the first exterior material opening (210). The second cap (320) can be sealed by being coupled to the inner surface of the exterior material (200) after being inserted into the second exterior material opening (220). Here, the inner surface of the exterior material (200) to which the first and second caps (310, 320) are coupled may be the aforementioned second resin layer. Additionally, the first and second caps (310, 320) may be coupled to the inner surface of the exterior material (200) at one side and the other side of the internal space (S), respectively.

[0066] The length of the portion of the first and second caps (310, 320) that is inserted into the interior of the exterior material (200) can be formed in various ways. For example, as shown in FIG. 2, only a portion of the first and second caps (310, 320) is inserted into the interior of the exterior material (200), and the remaining portion of the first and second caps (310, 320) may be exposed to the outside of the exterior material (200). Additionally, although not shown in FIG. 2, the entire first and second caps (310, 320) may be inserted into the interior of the exterior material (200).

[0067] The first and second caps (310, 320) may be made of a material that is not easily permeable to moisture in order to be combined with the inner surface of the exterior material (200) and to seal the inner space (S) of the exterior material (200). For example, the first and second caps (310, 320) may be obtained from metal or resin, or from a laminate sheet in which a resin layer is formed on both sides of a metal layer.

[0068] Meanwhile, as the secondary battery (10) is repeatedly charged and discharged, gas is generated, which may increase the pressure inside the outer material (200). If the pressure inside the outer material (200) increases excessively, venting may occur, and the secondary battery (10) may lose its function.

[0069] Specifically, an electrolyte may be contained within the outer casing (200) of the secondary battery (10) along with an electrode assembly (100). At this time, residual moisture of the electrolyte or moisture that has penetrated from the outside may react with the lithium salt within the outer casing (200) of the secondary battery (10) to generate HF, and gases such as carbon dioxide, carbon monoxide, ethylene, and methane may be generated through the decomposition of the electrolyte.

[0070] Additionally, depending on the positive electrode material included in the electrode assembly (100) of the secondary battery (10), hydrogen and HF may be additionally generated, which may cause overheating due to overcharging and internal short circuits during the charging and discharging process. Accordingly, a large amount of gas may be generated inside the outer casing (200). Due to such gas, the pressure inside the outer casing rises, and due to the increased pressure, a swelling phenomenon in which the outer casing (200) bulges or a venting phenomenon in which a part of the outer casing (200) bursts may occur.

[0071] The secondary battery (10) according to the first embodiment of the present invention may have a feature for inducing venting in a specific direction when the internal pressure increases. Specifically, the bonding force between the inner surface of the first cap (310) and the outer material (200) may be stronger than the bonding force between the inner surface of the second cap (320) and the outer material (200).

[0072] In this case, the inner surface of the first cap (310) and the outer material (200), through which the positive lead (110) and the negative lead (120) pass, is strongly bonded, so the bond between the first cap (310) and the outer material (200) will not be released even when the internal pressure of the secondary battery (10) increases. On the other hand, the inner surface of the second cap (320) and the outer material (200), which are provided on the opposite side of the first cap (310), is relatively weakly bonded, so the bond between the inner surface of the second cap (320) and the outer material (200) can be easily released when the internal pressure of the secondary battery (10) increases.

[0073] That is, when the internal pressure of the secondary battery (10) increases, a venting phenomenon occurs at the part where the second cap (320) is attached, so the venting phenomenon can be induced to the opposite side of the positive and negative leads (110, 120). In this case, there is an advantageous effect of preventing damage to the positive and negative leads (110, 120) even when the internal pressure of the secondary battery (10) increases.

[0074] Meanwhile, FIG. 3 is a perspective view showing a secondary battery according to the first embodiment of the present invention with a pressurizing member coupled thereto.

[0075] FIG. 3 illustrates a secondary battery (10) according to the first embodiment of the present invention having a pressurizing member (400) provided to press the portion of the outer material (200) that is coupled to the first cap (310) toward the first cap (310). When the pressurizing member (400) is provided in the secondary battery (10), a pressurizing force in the inward direction is applied to the outer side of the outer material (200) and the first cap (310), thereby providing an advantageous effect of preventing the coupling between the outer material (200) and the first cap (310) from being released even when the internal pressure of the secondary battery (10) increases. When the pressurizing member (400) is provided, the coupling force between the inner surface of the first cap (310) and the outer material (200) can be formed in various ways. For example, the coupling force between the inner surface of the first cap (310) and the outer material (200) can be 500 kPa or more.

[0076] The pressure member (400) can be configured in various ways. For example, the pressure member (400) may be a curable resin applied to the outer surface of the part of the exterior material (200) combined with the first cap (310). Additionally, the pressure member (400) may be made of a metal material and fitted onto the outer surface of the part of the exterior material (200) combined with the first cap (310).

[0077] Meanwhile, FIG. 4 is a cross-sectional view for explaining the structure of a first cap among secondary batteries according to a first embodiment of the present invention.

[0078] Referring to FIG. 4, the first cap (310) may include a body portion (310a) through which the positive lead (110) and the negative lead (120) pass, and a gasket (310b) formed on the outer surface of the body portion (310a) and coupled with an outer material (200).

[0079] In the body portion (310a), first and second through holes (311, 312) through which the positive lead (110) and the negative lead (120) pass may be formed. A sealing member may be inserted between these through holes (311, 312) and the electrode leads (110, 120).

[0080] The gasket (310b) is a member that surrounds the body portion (310a) and is made of PP material, and can be fused to the inner surface of the body portion (310a) and the exterior material (200), respectively. At this time, the gasket (310b) may have a thickness of 0.5 mm or more, and in this case, the gasket (310b) is sufficiently fused to the inner surface of the body portion (310a) and the exterior material (200), thereby improving the bonding strength between the first cap (310) and the exterior material (200). Specifically, the gasket (310b) may have a thickness of 0.5 mm or more and 1 mm or less. When the gasket (310b) is made of PP material with a thickness of 0.5 mm or more, the bonding strength between the inner surface of the first cap (310) and the exterior material (200) can be formed in various ways. For example, the bonding force between the first cap (310) and the inner surface of the outer material (200) may be 500 kPa or more.

[0081] 2nd embodiment

[0082] The secondary battery according to the second embodiment of the present invention differs from the first embodiment in that only one cap is attached to the outer casing. Details common to the first embodiment will be omitted as much as possible, and the second embodiment will be described focusing on the differences. That is, it is self-evident that if details not explained in the second embodiment are necessary, they can be considered as belonging to the first embodiment.

[0083] FIG. 5 is an exploded perspective view of a secondary battery according to a second embodiment of the present invention. FIG. 6 is a perspective view showing a pressurizing member coupled to a secondary battery according to a second embodiment of the present invention. FIG. 7 is a cross-sectional view for explaining the cap structure of a secondary battery according to a second embodiment of the present invention.

[0084] Referring to FIGS. 5 to 7, a secondary battery (10') according to a second embodiment of the present invention may include an electrode assembly (100'), an internal space (S') that accommodates the electrode assembly (100'), an exterior material (200') having an exterior material opening (210') that communicates the internal space (S') with the outside, a cap (310') that seals the exterior material opening (210'), and a positive lead (110') and a negative lead (120') that are connected to the electrode assembly (100') and at least a portion of which penetrates the cap (310') and is exposed to the outside. At this time, only one exterior material opening (210') is formed in the exterior material (200'), and the cap (310') may be coupled to the inner surface of the portion of the exterior material (200') where the exterior material opening (210') is formed.

[0085] In this case, the bonding force between the inner surface of the cap (310') and the outer material (200') through which the positive lead (110') and the negative lead (120') pass may be 500 kPa or more. If the internal pressure of the outer material (200') is 500 kPa or more, the outer material (200'), which is composed of a laminate sheet, may break. Since the bonding force between the inner surface of the cap (310') and the outer material (200') is 500 kPa or more, the bond between the cap (310') and the outer material (200') may not be released until the outer material (200') breaks.

[0086] That is, according to the second embodiment of the present invention, the secondary battery (10') can prevent venting from occurring toward the cap (310') through which the positive lead (110') and the negative lead (120') pass, and thus prevent damage to the positive lead (110') and the negative lead (120') even when venting occurs in the secondary battery (10').

[0087] The cap (310') may be a member that is attached to the outer material (200') and blocks the opening (210') of the outer material. The internal space (S') of the outer material (200') in which the electrode assembly (100') is housed may be filled with an electrolyte, and the cap (310') may seal the internal space (S') to prevent the electrolyte from leaking out.

[0088] Specifically, the cap (310') can be inserted into the outer material opening (210') and then bonded to the inner surface of the outer material (200') to seal the outer material opening (210'). Here, the inner surface of the outer material (200') to which the cap (310') is bonded can be the second resin layer described above in the secondary battery according to the first embodiment. Additionally, the cap (310') can be bonded to the inner surface of the outer material (200') on one side of the internal space (S').

[0089] At this time, the length of the portion of the cap (310') that is inserted into the interior of the exterior material (200') can be formed in various ways. For example, only a part of the cap (310') may be inserted into the interior of the exterior material (200'), and the remaining part of the cap (310') may be exposed to the outside of the exterior material (200'). In addition, the entire cap (310') may be inserted into the interior of the exterior material (200').

[0090] Meanwhile, the cap (310') may be made of a material that is not easily permeable to moisture in order to be combined with the inner surface of the exterior material (200') and to seal the inner space (S') of the exterior material (200'). For example, the cap (310') may be obtained from metal or resin, or from a laminate sheet in which a resin layer is formed on both sides of a metal layer.

[0091] The cap (310') may include a body portion (310a') through which the positive lead (110') and the negative lead (120') pass, and a gasket (310b') formed on the outer surface of the body portion (310a') and coupled with an outer casing (200'). First and second through holes (311', 312') through which the positive lead (110') and the negative lead (120') pass may be formed in the body portion (310a'). A sealing member may be inserted between these through holes (311', 312') and the electrode leads (110', 120').

[0092] The gasket (310b') is a member that surrounds the body part (310a') and is made of PP material and can be fused to the inner surface of the body part (310a') and the exterior material (200'), respectively. At this time, the gasket (310b') may have a thickness of 0.5 mm or more. Specifically, the gasket (310b') may have a thickness of 0.5 mm or more and 1 mm or less. In this case, the gasket (310b') is sufficiently fused to the inner surface of the body part (310a') and the exterior material (200'), thereby improving the bonding strength between the first cap (310') and the exterior material (200').

[0093] Meanwhile, the secondary battery (10') according to the second embodiment of the present invention may further include a pressing member (400') that presses the portion of the outer material (200') combined with the cap (310') toward the cap (310'). When the pressing member (400') is provided in the secondary battery (10'), a pressing force in the inward direction is applied to the outer side of the outer material (200') and the cap (310'), so that the coupling between the outer material (200') and the cap (310') can be prevented even when the internal pressure of the secondary battery (10') increases.

[0094] The pressure member (400') can be configured in various ways. For example, the pressure member (400') may be a curable resin applied to the outer surface of the part of the exterior material (200') combined with the cap (310'). Additionally, the pressure member (400') may be made of a metal material and fitted onto the outer surface of the part of the exterior material (200') combined with the cap (310').

[0095] Method for manufacturing secondary batteries

[0096] First embodiment

[0097] FIG. 8 is a flowchart sequentially illustrating a method for manufacturing a secondary battery according to a first embodiment of the present invention.

[0098] Referring to FIG. 8, a method for manufacturing a secondary battery according to a first embodiment of the present invention may include the steps of: combining a positive lead (110) and a negative lead (120) with an electrode assembly (100) (S10); wrapping the electrode assembly (100) with a sheet-type outer material (200) to form an internal space (S) that accommodates the electrode assembly (100) and first and second outer material openings (210, 220) that communicate the internal space (S) with the outside (S20); sealing the first outer material opening (210) with a first cap (310) (S30); and sealing the second outer material opening (220) with a second cap (320) (S40). At this time, the positive lead (110) and the negative lead (120) penetrate the first cap (310) and are exposed to the outside, and the sealing strength of the first cap (310) sealing the first outer material opening (210) may be stronger than the sealing strength of the second cap (320) sealing the second outer material opening (220).

[0099] In this case, the bonding force between the inner surface of the first cap (310) through which the positive lead (110) and the negative lead (120) pass and the outer surface of the outer surface (200) is formed to be stronger than the bonding force between the inner surface of the second cap (320) located on the opposite side of the first cap (310) and the outer surface of the outer surface (200), so that when the internal pressure of the secondary battery (10) increases, the bond between the inner surface of the second cap (320) and the outer surface of the outer surface (200) can be preferentially released. That is, it is possible to prevent venting from occurring toward the side of the first cap (310) through which the positive lead (110) and the negative lead (120) pass, and thus, even if venting occurs in the secondary battery (10), damage to the positive lead (110) and the negative lead (120) can be prevented.

[0100] That is, according to the method for manufacturing a secondary battery according to the first embodiment of the present invention, a secondary battery (10) can be manufactured in which the positive lead (110) and the negative lead (120) are prevented from being damaged even when venting occurs.

[0101] The step (S10) of combining the positive lead (110) and the negative lead (120) to the electrode assembly (100) may be a step of connecting the positive lead (110) to the positive of the electrode assembly (100) and connecting the negative lead (120) to the negative of the electrode assembly (100). Specifically, it may be a step of connecting the positive lead (110) to the positive tab bundle after welding the positive non-positive parts of the electrode assembly (100), and connecting the negative lead (120) to the negative tab bundle after welding the negative non-positive parts of the electrode assembly (100).

[0102] In the step (S10) of combining the positive lead (110) and the negative lead (120) to the electrode assembly (100), the positive lead (110) and the negative lead (120) may be connected to one side of the electrode assembly (100). That is, the electrode assembly (100) combined with the positive lead (110) and the negative lead (120) may be a unidirectional cell.

[0103] The step (S20) of wrapping the electrode assembly (100) with a sheet-shaped exterior material (200) to form an internal space (S) that accommodates the electrode assembly (100) and first and second exterior material openings (210, 220) that communicate the internal space (S) with the outside may be a step of winding the sheet-shaped exterior material in one direction and joining one end (201) and the other end (202) of the exterior material.

[0104] Specifically, the sheet-type exterior material (200) is a sheet having a first end (201) and a second end (202) spaced apart from the first end (201) in a predetermined direction, and the exterior material (200) can be formed by rolling or folding the exterior material sheet so that the first end (201) and the second end (202) meet. The first end (201) and the second end (202) of the exterior material sheet can be joined to each other in various ways. For example, the first end (201) and the second end (202) can be bonded with an adhesive, or the first end (201) and the second end (202) can be heat-fused to each other by receiving heat and pressure.

[0105] FIG. 9 is a flowchart showing in detail the step of a first cap being coupled to an outer material in a method for manufacturing a secondary battery according to a first embodiment of the present invention.

[0106] Referring to FIG. 9, the step (S30) of sealing the first exterior material opening (210) with the first cap (310) may include the step (S31) of inserting the first cap (310) into the first exterior material opening (210) and the step (S32) of heat-fusing the first cap (310) to the inner surface of the exterior material (200).

[0107] In the step (S32) of heat-fusing the first cap (310) to the inner surface of the exterior material (200), the first cap (310) and the inner surface of the exterior material (200) may be heated and pressurized for 3 to 10 seconds at a temperature range of 210 to 230°C. The inner surface of the first cap (310) and the exterior material (200) may be heated and pressurized in various ways. For example, the inner surface of the first cap (310) and the exterior material (200) may be heated and pressurized with a high-temperature jig. When the inner surface of the first cap (310) and the exterior material (200) is heated and pressurized for 3 to 10 seconds at a temperature range of 210 to 230°C, the bonding force between the first cap (310) and the inner surface of the exterior material (200) may be formed in various ways. For example, the bonding force between the first cap (310) and the inner surface of the outer material (200) may be 500 kPa or more.

[0108] FIG. 10 is a flowchart showing in detail the step of a second cap being coupled to an outer material in a method for manufacturing a secondary battery according to the first embodiment of the present invention.

[0109] Referring to FIG. 10, the step (S40) of sealing the second exterior material opening (220) with the second cap (320) may include the step (S41) of inserting the second cap (320) into the second exterior material opening (220) and the step (S42) of heat-fusing the second cap (320) to the inner surface of the exterior material (200).

[0110] In the step (S42) of heat-fusing the second cap (320) to the inner surface of the outer surface (200), the second cap (320) and the inner surface of the outer surface (200) can be heated and pressurized in various ways. For example, the second cap (320) and the inner surface of the outer surface (200) can be heated and pressurized with a high-temperature jig.

[0111] In the step (S42) of heat-fusing the second cap (320) to the inner surface of the outer surface (200), the total amount of heat applied to the second cap (320) and the inner surface of the outer surface (200) may be lower than the total amount of heat applied to the first cap (310) and the inner surface of the outer surface (200) in the step (S32) of heat-fusing the first cap (310) to the inner surface of the outer surface (200).

[0112] Meanwhile, the step (S30) of sealing the first exterior material opening (210) with the first cap (310) and the step (S40) of sealing the second exterior material opening (220) with the second cap (320) may be performed simultaneously or sequentially.

[0113] Specifically, the insertion of the first cap (310) into the first exterior material opening (210) and the insertion of the second cap (320) into the second exterior material opening (220) can be performed simultaneously or sequentially. Additionally, the fusion of the inner surface of the first cap (310) and the exterior material (200) and the fusion of the inner surface of the second cap (320) and the exterior material (200) can be performed simultaneously or sequentially.

[0114] Meanwhile, the method for manufacturing a secondary battery according to the first embodiment of the present invention is performed after the step (S40) of sealing the second outer material opening (220) with the second cap (320), and may include the step (S50) of applying a curable resin to the outer surface of the portion of the outer material (200) combined with the first cap (310).

[0115] The resin applied along the outer surface of the part of the outer material (200) that is combined with the first cap (310) hardens after a certain period of time, allowing pressure to be applied to the outer material (200) and the first cap (310). In this case, the outer material (200) adheres to the first cap (310) due to the hardened resin, so there is an advantageous effect of preventing the bond between the outer material (200) and the first cap (310) from being released even when the internal pressure of the secondary battery (10) increases.

[0116] Meanwhile, the method for manufacturing a secondary battery according to the first embodiment of the present invention is performed after the step (S40) of sealing the second outer casing opening (220) with the second cap (320), and may include the step (not shown) of fitting a pressure member (400) onto the outer surface of the portion of the outer casing (200) that is coupled with the first cap (310). The pressure member (400) is made of a metal material and can apply pressure to the outer casing (200) and the first cap (310). In this case, the outer casing (200) is in close contact with the first cap (310) by the pressure member (400), so there is an advantageous effect of preventing the coupling between the outer casing (200) and the first cap (310) from being released even when the internal pressure of the secondary battery (10) increases.

[0117] 2nd embodiment

[0118] The method for manufacturing a secondary battery according to the second embodiment of the present invention differs from the first embodiment in that only one cap is attached to the outer material. Content common to the first embodiment will be omitted as much as possible, and the second embodiment will be described focusing on the differences. That is, it is obvious that if content not explained in the second embodiment is necessary, it can be considered as content of the first embodiment.

[0119] FIG. 11 is a flowchart sequentially illustrating a method for manufacturing a secondary battery according to a second embodiment of the present invention.

[0120] Referring to FIG. 11, a secondary battery manufacturing method according to a second embodiment of the present invention may include the step of combining a positive lead (110') and a negative lead (120') with an electrode assembly (100') (S10'), the step of wrapping the electrode assembly (100') with a sheet-type outer material to form an internal space (S') that accommodates the electrode assembly (100') and an outer material opening (210') that communicates the internal space (S') with the outside (S20'), and the step of sealing the outer material opening (210') with a cap (310') (S30'). At this time, at least a portion of the positive lead (110') and the negative lead (120') penetrate the cap (310') and are exposed to the outside, and only one outer material opening (210') is formed in the outer material (200'), and the cap (310') can be bonded to the inner surface of the portion of the outer material (200') where the outer material opening (210') is formed. Additionally, the bonding force between the inner surface of the cap (310') and the outer material (200') through which the positive lead (110') and the negative lead (120') penetrate may be 500 kPa or more. If the internal pressure of the exterior material (200') is 500 kpa or more, the exterior material (200') composed of a laminate sheet may break, and since the bonding force between the cap (310') and the inner surface of the exterior material (200') is 500 kpa or more, the bond between the cap (310') and the exterior material (200') may not be released until the exterior material (200') breaks.

[0121] That is, according to the method for manufacturing a secondary battery according to the second embodiment of the present invention, venting to the side of the cap (310') through which the positive lead (110') and the negative lead (120') pass can be prevented. Therefore, a secondary battery (10') can be provided that prevents damage to the positive lead (110') and the negative lead (120') even when the internal pressure of the secondary battery increases.

[0122] Meanwhile, the step (S30') of sealing the exterior material opening (210') with a cap (310') may include the step of inserting the cap (310') into the exterior material opening (210') and the step of heat-fusing the cap (310') to the inner surface of the exterior material (200'). In the step of heat-fusing the cap (310') to the inner surface of the exterior material (200'), the cap (310') and the inner surface of the exterior material (200') may be heated and pressurized for 3 to 10 seconds at a temperature range of 210 to 230°C.

[0123] A method for manufacturing a secondary battery according to a second embodiment of the present invention is performed after the step of sealing the opening (210') of the outer material with a cap (310'), and may further include the step (S40') of applying a curable resin to the outer surface of the portion of the outer material (200') that is combined with the cap (310'). The resin applied along the outer surface of the portion of the outer material (200') that is combined with the cap (310') hardens after a certain period of time, thereby allowing pressure to be applied to the outer material (200') and the cap (310'). In this case, the outer material (200') adheres to the cap (310') due to the hardened resin, so that the bond between the outer material (200') and the cap (310') is prevented from being released even when the internal pressure of the secondary battery (10') increases.

[0124] Alternatively, the method for manufacturing a secondary battery according to the second embodiment of the present invention is performed after the step of sealing the opening (210') of the outer material with a cap (310'), and may include the step (not shown) of fitting a pressure member (400') onto the outer surface of the part of the outer material (200') that is combined with the cap (310'). The pressure member (400') is made of a metal material and can apply pressure to the outer material (200') and the cap (310'). In this case, the outer material (200') is in close contact with the cap (310') by the pressure member (400'), so that the connection between the outer material (200') and the cap (310') is prevented even when the internal pressure of the secondary battery (10') increases.

[0125] Although the present invention has been described above by limited embodiments and drawings, the present invention is not limited thereto, and various implementations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

[0126] [Explanation of the symbol]

[0127] 10: Secondary battery

[0128] 100: Electrode assembly

[0129] 110: Positive lead

[0130] 120: Cathode lead

[0131] 200: Exterior materials

[0132] 210: First exterior material opening

[0133] 220: Second exterior material opening

[0134] 310: 1st Cap

[0135] 311: First penetration

[0136] 312: Second penetration hole

[0137] 320: Second Cap

[0138] 400: Pressurizing member

Claims

1. Electrode assembly; An exterior material having an internal space accommodating the electrode assembly and first and second exterior material openings communicating the internal space with the outside; A first cap sealing the opening of the first exterior material; A second cap sealing the opening of the second exterior material; and It includes a positive lead and a negative lead connected to the electrode assembly, with at least a portion of which penetrates the first cap and is exposed to the outside, and A secondary battery in which the first cap and the second cap are bonded to the inner surface of the outer surface, and the bonding force between the first cap and the inner surface of the outer surface is stronger than the bonding force between the second cap and the inner surface of the outer surface.

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

3. In Claim 2, A secondary battery in which one end and the other end of the above exterior material sheet are bonded or fused to each other.

4. In Claim 1, A secondary battery further comprising a pressurizing member that presses the portion of the exterior material combined with the first cap toward the first cap.

5. In Claim 4, The above-mentioned pressure member is, A secondary battery comprising a resin cured on the outer surface of the portion combined with the first cap among the above exterior materials.

6. In Claim 1, The above-mentioned first cap is, A body portion through which the positive lead and the negative lead pass; and A secondary battery comprising a gasket formed on the outer surface of the body portion and coupled with the exterior material.

7. In Claim 6, The thickness of the above gasket is 0.5 mm or more, and The above gasket is a secondary battery composed of PP material.

8. Electrode assembly; An exterior material having an internal space accommodating the electrode assembly and an exterior material opening communicating the internal space with the outside; A cap sealing the opening of the exterior material; and It includes a positive lead and a negative lead connected to the electrode assembly, with at least a portion penetrating the cap and being exposed to the outside, A secondary battery in which only one opening is formed in the exterior material, and the cap is coupled to the inner surface of the portion of the exterior material in which the opening is formed.

9. In Claim 8, A secondary battery further comprising a pressure member that presses the portion of the exterior material combined with the cap toward the cap side.

10. In Claim 9, The above-mentioned pressure member is, A secondary battery comprising a cured resin on the outer surface of the part combined with the cap among the above exterior materials.

11. A step of combining the positive lead and the negative lead to the electrode assembly; A step of wrapping the electrode assembly with a sheet-type exterior material to form an internal space accommodating the electrode assembly and first and second exterior material openings communicating the internal space with the outside; A step of sealing the opening of the first exterior material with a first cap; and The method includes the step of sealing the opening of the second exterior material with a second cap, At least a portion of the positive lead and the negative lead penetrates the first cap and is exposed to the outside, and A method for manufacturing a secondary battery in which the sealing strength of the first cap sealing the first outer material opening is stronger than the sealing strength of the second cap sealing the second outer material opening.

12. In Claim 11, The step of sealing the first exterior material opening with a first cap is A step of inserting the first cap into the opening of the first exterior material; and A method for manufacturing a secondary battery comprising the step of heat-fusing the first cap to the inner surface of the outer material.

13. In Claim 12, A method for manufacturing a secondary battery, wherein in the step of heat-fusing the first cap to the inner surface of the outer surface of the outer surface, the first cap and the inner surface of the outer surface are heated and pressurized for 3 to 10 seconds at a temperature range of 210 to 230°C.

14. In Claim 11, The step of sealing the second exterior material opening with a second cap is A step of inserting the second cap into the opening of the second exterior material; and A method for manufacturing a secondary battery comprising the step of heat-fusing the second cap to the inner surface of the outer material.

15. In Claim 11, A method for manufacturing a secondary battery in which the step of sealing the first outer casing opening with a first cap and the step of sealing the second outer casing opening with a second cap are performed simultaneously or sequentially.

16. In Claim 11, A method for manufacturing a secondary battery, which is performed after the step of sealing the opening of the second outer material with a second cap, and further comprises the step of applying a curable resin to the outer surface of the portion of the outer material combined with the first cap.

17. A step of combining the positive lead and the negative lead to the electrode assembly; A step of wrapping the electrode assembly with a sheet-type exterior material to form an internal space accommodating the electrode assembly and an exterior material opening communicating the internal space with the outside; and The method includes the step of sealing the opening of the exterior material with a cap, At least a portion of the positive lead and the negative lead penetrates the cap and is exposed to the outside, A method for manufacturing a secondary battery in which only one opening is formed in the exterior material, and the cap is coupled to the inner surface of the portion of the exterior material where the opening is formed.

18. In Claim 17, The step of sealing the opening of the exterior material with a cap is A step of inserting the cap into the opening of the exterior material; and A method for manufacturing a secondary battery comprising the step of heat-fusing the cap to the inner surface of the outer material.

19. In Claim 18, A method for manufacturing a secondary battery, wherein in the step of heat-fusing the cap to the inner surface of the outer surface of the outer surface, the cap and the inner surface of the outer surface are heated and pressurized for 3 to 10 seconds at a temperature range of 210 to 230°C.

20. In Claim 17, A method for manufacturing a secondary battery, which is performed after the step of sealing the opening of the outer material with a cap, and further comprises the step of applying a curable resin to the outer surface of the portion of the outer material combined with the cap.

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