Secondary battery

Abstract

This invention relates to secondary batteries, and more specifically, to rechargeable secondary batteries. A secondary battery according to an embodiment of the invention may include: an electrode assembly; a pouch-shaped outer casing having an internal space for receiving the electrode assembly and an external casing opening for communicating the internal space with the outside; a cover member inserted into the external casing opening to seal the internal space; and a gas bag formed on the pouch-shaped outer casing to collect gas generated in the internal space.

Description

Technical Field

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2023-0183578, filed on December 15, 2023, and Korean Patent Application No. 10-2024-0178695, filed on December 4, 2024, the disclosures of which are incorporated herein by reference. Technical Field

[0004] This disclosure relates to secondary batteries, and more specifically, to secondary batteries that are rechargeable and dischargeable. Background Technology

[0005] A secondary battery (rechargeable battery) is a battery that can be charged and discharged, unlike a primary battery which cannot be recharged. Small secondary batteries are used in portable electronic devices such as mobile phones, laptops, and cameras, while medium or large secondary batteries are widely used as power sources for motors in vehicles such as hybrid vehicles.

[0006] The secondary battery can be classified in several ways based on the type of external material that houses the electrode assembly. For example, secondary batteries can be classified as: prismatic secondary batteries, in which the electrode assembly is housed inside a prismatic metal can; cylindrical secondary batteries, in which the electrode assembly is housed inside a cylindrical metal can; and pouch-type secondary batteries, in which the electrode assembly is housed inside a pouch-shaped box.

[0007] This type of pouch-shaped secondary battery can be manufactured by combining pouch-shaped boxes in which cup-shaped portions are formed. Figure 1 This is a view showing an example of a pouch-type secondary battery. Figure 1 The secondary battery 1 may include a pouch-shaped box 2 for housing electrode assemblies and electrode leads 3 protruding from two sides of the pouch-shaped box. In this case, a cup-shaped portion is molded in the pouch-shaped box 2, and the electrode assemblies can be housed inside the molded cup-shaped portion.

[0008] Figure 2 This is a view showing the cup-shaped portion of a pouch-type secondary battery. Figure 2 The image shows a pouch film 2 being pressed downwards. A concave cup-shaped portion 2' is formed in the pouch film 2. The molding depth of the cup-shaped portion 2' is limited by the material properties of the pouch film 2. Therefore, it is difficult to mold the cup-shaped portion 2' deep enough to increase the capacity of the secondary battery, and as the thickness of the pouch film 2 thins during molding the cup-shaped portion 2', defects such as cracks are prone to occur in the cup-shaped portion 2'.

[0009] Meanwhile, as the pouch-type secondary battery is repeatedly charged and discharged, gas can be generated inside the pouch-type box. Figure 3 This is a view showing the gas generated inside a pouch cell. Figure 3 The illustration shows the expansion of the pouch 2 due to repeated charging and discharging of the secondary battery 1. As this expansion continues, the problem is that the pouch 2 may rupture, causing internal electrolyte leakage and the release of high-pressure gases into the surrounding environment. Summary of the Invention

[0010] Technical issues

[0011] This disclosure aims to address the problems in the related technology, and therefore aims to provide a secondary battery that can solve the problems that arise during the molding of the cup-shaped portion in a bag.

[0012] This disclosure also aims to provide a secondary battery that can solve the problem of damage to the bag-shaped box caused by gas generated inside the bag-shaped box during continuous charging and discharging of the secondary battery.

[0013] Technical solution

[0014] The secondary battery according to Embodiment 1 of this disclosure may include: an electrode assembly; a pouch-shaped outer material having an internal space for accommodating the electrode assembly and an external material opening that allows communication between the internal space and the outside; a cover member inserted into the external material opening to seal the internal space; and a gas bag formed on the pouch-shaped outer material to trap gas generated in the internal space.

[0015] The bag-shaped outer material can be formed by rolling or folding an outer material sheet such that one end of the outer material sheet, including the metal layer, is joined to the other end.

[0016] One end of the outer material sheet and the other end can be glued or fused together.

[0017] The gas bag can be attached to the outer material of the bag.

[0018] One end of the gas bag can be connected to the outer material of the bag, and the other end of the gas bag can be connected to the cover component.

[0019] The other end of the gas bag can be attached to the cover component by adhesive or fusion bonding.

[0020] The gas bag can be connected to the internal space to form a gas capture space for capturing gases generated in the internal space.

[0021] Gas bags can have the shape of an empty hexahedral box that has been folded.

[0022] The gas bag may include: a first fold portion that is folded in one direction; and a second fold portion that is connected to the first fold portion and is folded in a different direction from the first fold portion.

[0023] The secondary battery according to Embodiment 1 of this disclosure may further include a pulling member for pulling the second folded portion toward the cover member.

[0024] The pulling member may include a strap, one end of which is attached to the tip portion of the second fold, and the other end of which is attached to the cover member.

[0025] A lead insertion hole may be formed in the cover member, into which an electrode lead electrically connected to the electrode assembly is inserted.

[0026] An electrolyte injection port for injecting electrolytes into the internal space can be formed in the cover component.

[0027] In the secondary battery according to Embodiment 2 of this disclosure, multiple gas bags can be formed in the outer material of the bag shape.

[0028] The cover component can have a cube shape.

[0029] Each of the multiple gas bags can come into contact with a different surface of the cover component.

[0030] Beneficial effects

[0031] According to the secondary battery disclosed herein, since a pouch-shaped outer material can be provided without molding a cup-shaped portion for housing the electrode assembly, the advantages are that the battery capacity can be increased by increasing the size of the pouch-shaped outer material, the material or thickness of the outer material sheet used to manufacture the pouch-shaped outer material can be freely selected, and defects such as cracks can be prevented in the pouch-shaped outer material.

[0032] Furthermore, according to the secondary battery of this disclosure, a gas bag is formed in the outer material of the bag type to capture the gas generated in the internal space, and thus has the advantageous effect of delaying or preventing damage to the bag due to internal pressure. Attached Figure Description

[0033] Figure 1 This is a view showing an example of a pouch-type secondary battery.

[0034] Figure 2 This is a view showing the cup-shaped portion of a pouch-type secondary battery.

[0035] Figure 3This is a view showing the generation of gas inside a pouch cell.

[0036] Figure 4 This is a perspective view of a secondary battery according to Embodiment 1 of this disclosure.

[0037] Figure 5 It is based on Figure 4 An exploded 3D view of a secondary battery.

[0038] Figure 6 This is an unfolded view of the outer material sheet constituting the secondary battery according to Embodiment 1 of this disclosure.

[0039] Figure 7 This is a perspective view showing the state in which the second part of the outer material sheet folded into a cubic box shape in a secondary battery according to Embodiment 1 of the present disclosure is disposed on the upper side of the cover member.

[0040] Figure 8 It is along Figure 7 A cross-sectional view taken in the XX' direction.

[0041] Figure 9 It shows Figure 8 A cross-sectional view of the gas bag being pressed along the AA' direction.

[0042] Figure 10 It shows Figure 9 A cross-sectional view of the gas bag in a folded state.

[0043] Figure 11 yes Figure 10 A magnified view of part B.

[0044] Figure 12 This is a view used to describe the process by which gas in the internal space of a secondary battery according to Embodiment 1 of the present disclosure is captured into a gas bag.

[0045] Figure 13 This is a cross-sectional view showing the traction member attached to the gas bag in a secondary battery according to Embodiment 1 of the present disclosure.

[0046] Figure 14 This is a front view of the secondary battery according to Embodiment 2 of this disclosure. Detailed Implementation

[0047] In the following description, preferred embodiments of the present disclosure will be described in sufficient detail with reference to the accompanying drawings to enable those skilled in the art to readily implement the disclosure. However, the present disclosure may be implemented in many different forms and is not limited to or construed as described below.

[0048] In order to clearly describe this disclosure, irrelevant descriptions or detailed descriptions of related known technologies that may unnecessarily obscure the essential points of this disclosure have been omitted, and throughout the disclosure, the same or similar reference numerals are attached to the same or similar elements when reference numerals are attached to elements in each figure.

[0049] Additionally, it should be understood that the terms or words used in this disclosure and the appended claims should not be construed as limited to their general or dictionary meanings, but rather interpreted based on their meanings and concepts corresponding to the technical aspects of this disclosure, on the basis of the principle that inventors are permitted to define terms appropriately for the purpose of best illustration.

[0050] In the following description, a secondary battery according to the present disclosure will be described with reference to the accompanying drawings.

[0051] Implementation Method 1

[0052] Figure 3 It is a view showing the generation of gas inside a pouch cell, and Figure 4 This is a perspective view of a secondary battery according to Embodiment 1 disclosed in this invention.

[0053] Reference Figure 3 and Figure 4 According to Embodiment 1 of this disclosure, the secondary battery 10 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 external material opening 210 for allowing communication between the internal space 220 and the outside; a cover member 300 inserted into the external material opening 210 to seal the internal space 220; and a gas bag 230 formed on the pouch-shaped outer material 200 to trap gas generated in the internal space 220.

[0054] The electrode assembly 100 is a stacked assembly including a positive electrode, a negative electrode, and a separator, and can have various structures. For example, the electrode assembly can be a stacked electrode assembly in which the positive electrode, negative electrode, and separator are stacked in one direction, or a stack-folded electrode assembly in which the negative electrode, positive electrode, and separator are stacked in the same direction and then folded.

[0055] Here, the positive electrode may include a positive current collector and a positive active material coated on the positive current collector, and the negative electrode may include a negative current collector and a negative active material coated on the negative current collector. The separator is an insulating material film inserted between the positive and negative electrodes to prevent contact between the positive and negative electrodes, and multiple pores for positive ions to pass through may be formed in the separator.

[0056] The bag-shaped outer material 200 is formed by winding an outer material sheet 200a in one direction, and an internal space 220 for accommodating the electrode assembly 100 can be formed inside the wound outer material sheet 200a. Furthermore, both sides of the internal space 220 can communicate with the outside.

[0057] Specifically, the outer material 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 bag-type outer material 200 is formed by rolling or folding the outer material sheet 200a so that one end 201a and the other end 202a are joined together. One end 201a and the other end 202a of the outer material sheet 200a can be joined to each other in various ways. For example, one end 201a and the other end 202a can be bonded together by an adhesive, or one end 201a and the other end 202a can be thermally fused to each other by receiving heat and pressure.

[0058] One end 201a of the outer material sheet 200a can be attached to the inner or outer surface of the other end 202a. For example... Figure 5 As shown, the outer surface of one end 201a of the outer material sheet 200a can be connected to the inner surface of the other end 202a. Furthermore, the inner surface of one end 201a of the outer material sheet 200a can be connected to the inner surface of the other end 202a.

[0059] Meanwhile, the outer material sheet 200a can be a laminated sheet including a metal layer such as aluminum or stainless steel. In this case, a resin layer can be formed on each of the outer and inner surfaces of the metal layer.

[0060] The metal layer serves as a substrate for maintaining mechanical strength and a barrier layer to prevent the penetration of moisture and oxygen. The metal layer can be made of aluminum or aluminum alloys to not only prevent the ingress or leakage of foreign substances such as gases and moisture, but also to enhance the strength of the battery compartment. Aluminum alloys may include alloy numbers such as 8079, 1N30, 8021, 3003, 3004, 3005, 3104, 3105, etc., which can be used alone or in combination of both or more.

[0061] The first resin layer coated on the outer surface of the metal layer should have excellent resistance to the external environment to protect the electrode assembly from external influences, and therefore requires the first resin layer to have excellent tensile strength and durability relative to its thickness. Materials used for the first resin layer may include polyester-based resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), as well as polyolefin-based resins such as polyethylene and polypropylene.

[0062] A second resin layer coated on the inner surface of the metal layer can be coupled to the cover member 300, described later, to seal the interior space 220, and the second resin layer can be made of a polyolefin-based resin. For example, materials used for the second resin layer may include cast polypropylene (CPP), chlorinated polypropylene, polyethylene, ethylene-propylene copolymer, polyethylene-acrylic acid copolymer, polypropylene-acrylic acid copolymer, etc.

[0063] Conventionally, pouch-type secondary batteries are manufactured by molding a cup-shaped portion onto a pouch membrane, inserting electrode assemblies into the cup-shaped portion, and then sealing the pouch membrane containing the molded cup-shaped portion with another pouch membrane. However, the molding depth of the cup-shaped portion is limited by the material properties of the pouch membrane, and therefore the cup-shaped portion cannot be molded deeper to increase the capacity of the secondary battery. Furthermore, there is a problem that the thickness of the pouch membrane thins during the molding process of the cup-shaped portion, leading to defects such as cracks in the pouch membrane.

[0064] On the other hand, since the pouch-shaped outer material 200 of the secondary battery 10 according to this disclosure is prepared by rolling or folding the outer material sheet 200a, the electrode assembly 100 can be accommodated in the internal space 220 of the pouch-shaped outer material 200 without molding a separate cup-shaped portion. In this case, since the conventional limitations caused by forming a cup-shaped portion in the outer material are not imposed, the capacity of the secondary battery 10 can be easily increased by increasing the size of the internal space 220. Furthermore, since the pouch-shaped outer material 200 prepared by rolling or folding the outer material sheet 200a does not form a portion with reduced thickness, defects such as cracks can therefore be prevented from appearing in the pouch-shaped outer material 200.

[0065] For reference, the secondary battery 10 according to this disclosure can be formed by placing the electrode assembly 100 on the upper surface of the outer material sheet 200a in its unfolded state and then rolling or folding the outer material sheet 200b. Furthermore, the secondary battery 10 according to this disclosure can be formed by rolling or folding the outer material sheet 200a to form an internal space 220 and an outer material opening 210, and then inserting the electrode assembly 100 into the outer material opening 210. In both cases, the electrode assembly 100 can be housed within the pouch-shaped outer material 200 without molding a separate cup-shaped portion.

[0066] At the same time, refer to Figure 4 and Figure 5 The cover member 300 may be a member attached to the pouch-shaped outer material 200 and blocking the opening 210 of the outer material. The internal space 220 of the pouch-shaped outer material 200 that houses the electrode assembly 100 may be filled with electrolyte, and the cover member 300 may seal the internal space 220 to prevent electrolyte leakage from the internal space 220.

[0067] Specifically, a cover member 300, inserted into an external material opening 210 that allows communication between the internal space 220 and the outside, can be attached to the inner surface of the bag-shaped external material 200 and the other end 232 of the gas bag 230, which will be described later, thereby sealing the internal space 220 and the gas trapping space S, which will be described later. Here, the inner surface of the bag-shaped external material 200 can be the second resin layer described above.

[0068] Meanwhile, the length of the portion of the cover member 300 inserted into the outer material 200 of the bag type can be formed in various ways. For example, as... Figure 4 and Figure 5 As shown, only a portion of the cover member 300 can be inserted into the bag-shaped outer material 200, such that the remaining portion of the cover member 300 can be exposed to the outside of the bag-shaped outer material 200.

[0069] Furthermore, the cover member 300 can be made of a material that is not easily permeable by moisture. For example, the cover member 300 can be made of metal or resin, or it can be made of a laminated sheet in which resin layers are formed on both surfaces of a metal layer.

[0070] The cover member 300 can have various shapes. For example, the cover member 300 may include a body 310 and a gasket 320 to laterally block the internal space 220 of the outer material 200. Specifically, a through hole for the gas lead 120 to pass through can be formed in the body 310. The gasket 320 is a member surrounding the body 310 and can prevent electrolyte leakage between the outer material 200 and the body 310. In this case, the gasket 320 can be a medium for a rigid connection between the outer material 200 and the body 310.

[0071] The washer 320 can have various shapes. For example, the washer 320 can have a frame shape that surrounds the side surface of the outer surface of the body 310. In addition, the washer 320 can be formed to surround both the inner and outer surfaces of the body 310.

[0072] Meanwhile, the cap member 300 can be attached to the inner surface of the bag-shaped outer material 200 and the other end 232 of the gas bag 230 in various ways. For example, the cap member 300 can be attached to the inner surface of the bag-shaped outer material 200 and the other end 232 of the gas bag 230 by adhesive, or the cap member 300 can be thermally fused to the inner surface of the bag-shaped outer material 200 and the other end 232 of the gas bag 230.

[0073] The gas bag 230 is used to capture the gas generated in the internal space 220 by the charging and discharging of the secondary battery 10, and can be formed in the bag-shaped outer material 200. In this case, the gas generated in the internal space 220 is captured in the gas bag 230, and thus there is the advantageous effect of preventing the bag-shaped outer material 200 from expanding or tearing even when gas is generated in the internal space 220.

[0074] Meanwhile, the gas bag 230 is made of the same material as the outer material 200 of the bag and can be attached to the outer material 200 of the bag. That is, the gas bag 230 can be made of a laminated sheet including a metal layer such as aluminum or stainless steel. In this case, a resin layer can be formed on each of the outer and inner surfaces of the metal layer.

[0075] A lead insertion hole 311 may be formed in the body 310 of the cover member 300, into which an electrode lead 120 electrically connected to the electrode assembly 100 is inserted. The electrode lead 120 is coupled to an electrode tab 110, which is connected to each of the uncoated portions of the electrodes stacked in 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 lead insertion hole 311 may have a shape corresponding to the shape of the inserted electrode lead 120.

[0076] Simultaneously, a sealing member such as an O-ring can be inserted between the lead insertion hole 311 and the electrode lead 120, or a sealant layer made of thermoplastic resin can be formed. In this case, leakage of electrolyte injected into the internal space 220 through the lead insertion hole 311 can be prevented.

[0077] An electrolyte injection port for injecting electrolyte into the internal space 220 may be formed in the cover member 300. Here, the electrolyte injection port may be a through hole penetrating the cover member 300.

[0078] The electrolyte injection process for injecting electrolyte into the internal space 220 of the secondary battery 10 can be performed through the electrolyte injection port. For example, the user can inject electrolyte into the internal space 220 through the electrolyte injection port while the secondary battery 10 is positioned such that the cover member 300 with the electrolyte injection port is facing upwards.

[0079] In addition, a degassing process can be performed through the electrolyte injection port to discharge gases generated during the activation of the secondary battery 10 to the outside. For example, a user can open the electrolyte injection port to cause gas discharge from the internal space 220.

[0080] After the electrolyte injection or degassing process, the electrolyte injection port can be sealed or welded to seal the internal space 220. Alternatively, the electrolyte injection port can be opened only when necessary by installing a valve capable of opening and closing it.

[0081] On the other hand, conventional pouch-type secondary batteries have a gas bag formed by rolling up a portion of the external material, and the gas bag is removed from the external material after capturing the internal gas, resulting in the problem of repeated disposal of a portion of the external material. In this regard, the secondary battery 10 according to this disclosure includes an electrolyte injection port formed in the cover member 300, and the user can inject electrolyte into the internal space 220 and discharge gas from the internal space 220 to the outside through this electrolyte injection port, thereby solving the conventional problem of repeated disposal of a portion of the external material.

[0082] Figure 6 This is a unfolded view of the outer material sheet constituting the secondary battery of Embodiment 1 of this disclosure. (Refer to...) Figure 6 The outer material sheet 200a may include a first portion A that is rolled or folded in one direction to form a bag-shaped outer material 200, and a second portion B that is folded into a cubic box shape to form a gas bag 230. At this time, as... Figure 6 As shown, the first part A and the second part B can be connected to each other.

[0083] The second part B can be folded into a cubic box shape to form a gas bag 230, and the gas trapping space S inside the gas bag 230 can be connected to the internal space 220 of the outer material 200 of the bag shape. For this purpose, when the second part B is folded into a cubic box shape, Figure 6 The two edges (p, q) shown can remain unconnected to each other.

[0084] Specifically, when the second part B is folded into a cubic box shape, the two edges (p, q) face each other, and here, the two edges (p, q) can remain separate and not connected to each other. The two edges (p, q) can be one end 231 and the other end 232 of the gas bag 230, which will be described later.

[0085] at the same time, Figure 7 This is a perspective view showing the state in which the second part of the outer material sheet of the secondary battery according to Embodiment 1 of this disclosure is folded into a cubic box shape and disposed on the upper side of the cover member. Figure 8 It is along Figure 7 A cross-sectional view taken in the XX' direction.

[0086] Reference Figure 7 and Figure 8The second part B described above can be folded into a gas bag 230 with a cubic box shape. The gas bag 230 is disposed on the upper side of the cover member 300, and one end 231 and the other end 232 of the gas bag 230 can be separated from each other. Here, one end 231 of the gas bag 230 can be connected to the outer bag material 200, and the other end 232 of the gas bag 230 can be connected to the cover member 300.

[0087] Specifically, one end 231 of the gas bag 230 is supported by the other end 232 of the gas bag 230, but one end 231 and the other end 232 are not connected to each other, and therefore, when the internal pressure of the secondary battery 10 increases, one end 231 may separate from the other end 232. When the internal pressure of the secondary battery 10 increases, the internal gas of the secondary battery 10 can flow into the gas trapping space S through the space between one end 231 and the other end 232.

[0088] In this configuration, the gas trapping space S formed inside the gas bag 230 can communicate with the internal space 220 formed by the bag-shaped outer material 200. When the cover member 300 is attached to the bag-shaped outer material 200 and the gas bag 230, the gas trapping space S and the internal space 220 can be sealed relative to the outside. That is, the cover member 300 can be a sealing member that seals the gas trapping space S and the internal space 220.

[0089] Meanwhile, the other end 232 of the gas bag 230 can be connected to the cover member 300 in various ways. For example, the other end 232 of the gas bag 230 can be connected to the cover member 300 by adhesive or fusion.

[0090] at the same time, Figure 9 It shows Figure 8 A cross-sectional view of the gas bag being pressed in the AA' direction, and Figure 10 It shows Figure 9 A cross-sectional view of the gas bag in a folded state. (Refer to...) Figures 8 to 10 The empty cubic box-shaped gas bag 230 can be flattened by pressing from both sides and then folded into a zigzag shape to be placed on the upper part of the bag-shaped outer material 200 and the cover member 300.

[0091] In this configuration, the gas bag 230 is folded into a zigzag shape while flattened, thus reducing the volume occupied by the gas bag 230 within the secondary battery 10. In other words, the overall volume of the secondary battery 10 is reduced, which has the beneficial effect of rethinking the space utilization of the space where the secondary battery 10 is installed (e.g., the internal space of a battery module, battery pack, or electronic device).

[0092] at the same time, Figure 11 yes Figure 10 A magnified view of part B. Figure 11 A first folded portion 230a and a second folded portion 230b are shown. Specifically, the gas bag 230 may include a first folded portion 230a folded in one direction and a second folded portion 230b connected to the first folded portion 230a and folded in a different direction from the first folded portion 230a.

[0093] The first fold portion 230a is a portion of the gas bag 230 that folds from the upper side of the cover member 300 toward the upper side of the bag-shaped outer material 200, and the first fold portion 230a may include one end 231 and the other end 232 of the gas bag 230. The second fold portion 230b is a portion of the gas bag 230 that folds from the upper side of the bag-shaped outer material 200 toward the upper side of the cover member 300, and the second fold portion 230b may be connected to the first fold portion 230a.

[0094] In other words, the gas bag 230 can be folded into a zigzag shape and is positioned on the upper side of the bag-shaped outer material 200 and the cover member 300. The advantage of this configuration is that it minimizes the volume of the gas bag 230 when no gas flows into the gas trapping space S.

[0095] at the same time, Figure 12 This is a view used to describe the process by which gas in the internal space of a secondary battery according to Embodiment 1 of the present disclosure is captured into a gas bag. Figure 12 The diagram shows the flow of gas generated in the internal space 220 into the gas trapping space S of the gas bag 230 as the secondary battery 10 is charged and discharged.

[0096] Therefore, the gas bag 230, which is in a folded state, expands, and the internal pressure of the internal space 220 remains constant while the gas bag 230 expands, thus preventing or delaying the increase in pressure in the internal space 220. In this case, the advantageous effect is to prevent or delay the expansion or tearing of the bag-shaped outer material 200 due to the increased pressure in the internal space 220.

[0097] at the same time, Figure 13 This is a cross-sectional view showing the traction member attached to the gas bag in a secondary battery according to Embodiment 1 of this disclosure. (Refer to...) Figure 13According to Embodiment 1 of this disclosure, the secondary battery 10 may further include a pulling member 400 that pulls the second folded portion 230b toward the cover member 300. The pulling member 400 pulls the second folded portion 230b toward the cover member 300, and thus the gas bag 230 in the folded state can come into close contact with the cover member 300. That is, even when no gas is trapped in the gas trapping space S, the gas bag 230 is in close contact with the cover member 300, and therefore has the advantageous effect of reducing the overall volume of the secondary battery 10.

[0098] The pulling member 400 may be a belt 410, with one end 411 attached to the tip portion 230b' of the second folded portion 230b and the other end 412 attached to the cover member 300. Here, when gas is trapped in the gas trapping space S, the connection between one end 411 of the belt 410 and the tip portion 230b' of the second folded portion 230b can be released. Furthermore, when gas is trapped in the gas trapping space S, the connection between the other end 412 of the belt 420 and the cover member 300 can be released.

[0099] Specifically, when the gas generated in the internal space 220 flows into the gas trapping space S, the folded gas bag 230 can expand. As the gas bag 230 expands and its volume increases, the strap 410 may no longer keep the gas bag 230 in close contact with the side of the cover member 300. That is, as the gas bag 230 expands, the connection between one end 411 of the strap 410 and the tip portion 230b' of the second folded portion 230b can be released, or the connection between the other end 412 of the strap 410 and the cover member 300 can be released.

[0100] In this case, when the gas flows into the gas trapping space S, the adhesive bond of the tape 410 is released, and the resulting advantage is that the volume of the gas bag 230 is reduced by making the gas bag 230 in close contact with the side of the cover member 300 under normal conditions, without interfering with the gas being trapped into the gas trapping space S.

[0101] Implementation Method 2

[0102] The secondary battery according to Embodiment 2 of this disclosure differs from that of Embodiment 1 in that the secondary battery according to Embodiment 2 includes multiple gas bags. Content common to Embodiment 1 will be omitted as much as possible, and the description of Embodiment 2 will focus on the differences. That is, it is apparent that, if necessary, content not described in Embodiment 2 can be considered as part of Embodiment 1.

[0103] Figure 14This is a front view of the secondary battery according to Embodiment 2 of this disclosure. Figure 14 The diagram illustrates a configuration in which multiple gas bags 230a, 230b, 230c, and 230d are connected to a cover member 300. The secondary battery 10 according to Embodiment 2 of this disclosure 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 external material opening 210 allowing communication between the internal space 220 and the outside; a cover member 300 inserted into the external material opening 210 to seal the internal space 220; and multiple gas bags 230a, 230b, 230c, and 230d formed on the pouch-shaped outer material 200 to capture gases generated in the internal space 220. That is, a gas-capturing space for capturing gases generated in the internal space 220 may be formed in each of the multiple gas bags 230a, 230b, 230c, and 230d.

[0104] At this point, one end of each of the multiple gas bags 230a, 230b, 230c, and 230d can be connected to the outer bag material 200. That is, the multiple gas bags 230a, 230b, 230c, and 230d can be formed within the outer bag material 200. In this case, multiple free spaces are formed in the secondary battery 10 capable of trapping the gas generated in the internal space 220, which effectively prevents the outer bag material 200 from venting or tearing, even when a large amount of internal gas is generated.

[0105] Meanwhile, in the secondary battery 10 according to Embodiment 2 of this disclosure, the cover member 300 may have a cubic shape. In this case, each of the plurality of gas bags 230a, 230b, 230c, and 230d may contact different surfaces of the cover member 300. Specifically, one end of each of the plurality of gas bags 230a, 230b, 230c, and 230d may be attached to different surfaces of the cover member 300. Here, one end of each of the plurality of gas bags 230a, 230b, 230c, and 230d may be attached to the cover member 300 by adhesive bonding or fusion welding.

[0106] Each of the plurality of gas bags 230a, 230b, 230c, 230d may have a shape that allows an empty hexahedral box to be folded. Specifically, each of the plurality of gas bags 230a, 230b, 230c, 230d may include a first folded portion folded in one direction and a second folded portion folded in a direction different from the first folded portion.

[0107] Furthermore, the secondary battery 10 according to Embodiment 2 of this disclosure may also include a pulling member for pulling each of the plurality of gas bags 230a, 230b, 230c, 230d toward the cover member 300. Here, the pulling member may include a plurality of straps attached to each of the plurality of gas bags 230a, 230b, 230c, 230d. Specifically, one end of each strap may be attached to the tip portion of each of the plurality of gas bags 230a, 230b, 230c, 230d, and the other end of each strap may be attached to the cover member 300.

[0108] The present disclosure has been described above with respect to a limited number of embodiments and accompanying drawings, but the present disclosure is not limited thereto, and those skilled in the art to which the present disclosure pertains may implement the present disclosure in different forms within the scope of the technical aspects of the present disclosure and the appended claims and their equivalents.

[0109] [List of reference numerals]

[0110] 10: Secondary battery; 100: Electrode assembly

[0111] 110: Electrode contact piece; 120: Electrode lead wire

[0112] 200: External material; 201: Bag forming part

[0113] 202: Space-forming part; 200a: External material sheet

[0114] 201a: One end of the outer material sheet; 202a: The other end of the outer material sheet.

[0115] 210: External material opening; 220: Internal space

[0116] 230: Gas bag; 230a: First fold section

[0117] 230b: Second fold section; 300: Cover component

[0118] 310: Body; 320: Washer

[0119] 400: Tension member; 410: Belt

Claims

1. A secondary battery, comprising: Electrode assembly; A bag-shaped outer material having an internal space for accommodating the electrode assembly and an external material opening allowing communication between the internal space and the outside; A cover member, which is inserted into the external material opening to seal the internal space; as well as A gas bag, formed on the outer material of the bag shape, to trap gas generated in the internal space.

2. The secondary battery according to claim 1, wherein The bag-shaped outer material is formed by rolling or folding an outer material sheet such that one end of the outer material sheet, including the metal layer, is joined to the other end.

3. The secondary battery according to claim 2, wherein One end of the outer material sheet and the other end are bonded or fused together.

4. The secondary battery according to claim 1, wherein The gas bag is connected to the outer material of the bag shape.

5. The secondary battery according to claim 4, wherein One end of the gas bag is connected to the outer material of the bag shape, and The other end of the gas bag is connected to the cover member.

6. The secondary battery according to claim 5, wherein, The other end of the gas bag is attached to the cover member by adhesive or fusion bonding.

7. The secondary battery according to claim 1, wherein The gas bag is connected to the internal space to form a gas capture space for capturing gases generated in the internal space.

8. The secondary battery according to claim 1, wherein The gas bag has the shape of an empty hexahedral box that has been folded.

9. The secondary battery according to claim 8, wherein, The gas bag includes: A first folded portion, the first folded portion being folded in one direction; and The second fold portion is connected to the first fold portion and folded in a direction different from that of the first fold portion.

10. The secondary battery according to claim 9, further comprising: A pulling member that pulls the second folded portion toward the cover member.

11. The secondary battery according to claim 10, wherein The pulling member includes a strap, one end of which is attached to the tip portion of the second folded portion, and the other end of which is attached to the cover member.

12. The secondary battery according to claim 1, wherein A lead wire insertion hole is formed in the cover member, and an electrode lead wire electrically connected to the electrode assembly is inserted into the lead wire insertion hole.

13. The secondary battery according to claim 1, wherein An electrolyte injection port for injecting electrolytes into the internal space is formed in the cover member.

14. The secondary battery according to claim 1, wherein Multiple gas pockets are formed in the outer material of the bag.

15. The secondary battery according to claim 14, wherein The cover component has a cubic shape.

16. The secondary battery according to claim 15, wherein Each of the plurality of gas bags is in contact with a different surface of the cover member.

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