Secondary battery

Abstract

The present invention relates to a secondary battery that can be charged and discharged. The secondary battery according to an embodiment of the present invention may comprise: an electrode assembly; a sheet-type exterior material that has an inner space for accommodating the electrode assembly and an exterior material opening for communicating the inner space with the outside; a cap inserted into the exterior material opening to seal the inner space; and a fire protection member that is made of a flame-retardant material and coupled to the outer surface of a portion of the sheet-type exterior material overlapping with the cap.

Description

secondary battery

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0182559 filed on December 10, 2024, and all contents disclosed in the document of said Korean Patent Application are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present invention relates to a rechargeable secondary battery.

[0005] Batteries that store electrical energy can generally be classified into primary and secondary batteries. Primary batteries are disposable, consumable batteries, whereas secondary batteries are rechargeable batteries manufactured using materials capable of repeating oxidation and reduction processes between the electric current and the material. In other words, when a reduction reaction is performed on the material by the electric current, the power is charged, and when an oxidation reaction is performed, the power is discharged; electricity is generated as this charging and discharging cycle is repeatedly performed.

[0006] Secondary batteries can be classified into cylindrical cells, pouch cells, prismatic cells, etc., depending on their shape. Among these, pouch cells can be manufactured by housing an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked inside a pouch, and sealing the outer part of the pouch. An electrolyte can be housed inside the pouch of a pouch cell along with the electrode assembly. At this time, residual moisture in the electrolyte or moisture penetrating from the outside reacts with the lithium salt inside the pouch of the pouch cell 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 cell, 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. Consequently, flames may occur inside the pouch, and these flames may be discharged to the outside through the pouch of the pouch cell.

[0008] Meanwhile, if flames emitted externally propagate toward the electrode leads, there is a risk of damage to the electrode leads and the electronic devices or other secondary batteries connected to them. Therefore, even when flames are emitted from the secondary battery, it is necessary to block the propagation of the flames toward the electrode leads.

[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 blocking the propagation of flames toward the electrode leads even when flames generated in the internal space housing the electrode assembly are discharged to the outside.

[0010] A secondary battery according to a first embodiment of the present invention may include: an electrode assembly; a sheet-type outer material having an internal space accommodating the electrode assembly and an outer material opening communicating the internal space with the outside; a cap inserted into the outer material opening to seal the internal space; and a fireproof member made of a flame-retardant material coupled to the outer surface of the portion of the sheet-type outer material that overlaps with the cap.

[0011] The above cap may include a body having a through hole through which an electrode lead passes; and a gasket that surrounds the body and is coupled to the inner surface of the sheet-type outer material.

[0012] The above sheet-type exterior material may be formed by rolling or folding a laminate sheet so that one end and the other end of the laminate sheet having a multilayer structure meet each other.

[0013] The above sheet-type exterior material may include a space-forming portion that forms the internal space as part of the laminate sheet; and a side-folding portion in which one end and the other end of the laminate sheet are folded toward the space-forming portion.

[0014] The above secondary battery may further include a fixing member that fixes the side folding portion so that one side of the side folding portion contacts the space forming portion.

[0015] The above fireproof member may include a fireproof pad attached to the outer surface of the portion of the side folding part that overlaps with the cap.

[0016] The width of the fireproof pad may be the same as the short side length of the cap.

[0017] The ratio between the height of the fireproof pad and the width of the fireproof pad may be 1:5 to 1:20.

[0018] The width of the fireproof pad may be longer than the width of the portion where the side folding portion and the cap overlap.

[0019] The above laminate sheet may be composed of an inner layer made of a resin material and bonded to the cap; a metal layer made of a metal material formed on the outer surface of the inner layer; and an outer layer made of a resin material formed on the outer surface of the metal layer.

[0020] The above fireproof pad may include a polymer pad composed of urethane or silicone material that is heat-fused to the outer surface of the outer layer.

[0021] In a secondary battery according to a second embodiment of the present invention, the laminate sheet may be composed of an inner layer formed of a resin material and bonded to the cap; and a metal layer of a metal material formed on the outer surface of the inner layer.

[0022] The fireproof pad may include a metal pad made of aluminum or stainless steel that is welded to the outer surface of the metal layer.

[0023] According to a secondary battery according to one embodiment of the present invention, a fire-retardant member made of a flame-retardant material is attached to the outer surface of the portion of the sheet-type outer material that overlaps with the cap, so that even when a flame generated in the internal space in which the electrode assembly is housed is vented to the outside, the flame can be blocked from propagating to the cap equipped with the electrode lead.

[0024] FIG. 1 is an exploded perspective view of a secondary battery to explain a structure in which an electrode assembly according to the present invention is inserted into the internal space of a sheet-type outer material.

[0025] FIG. 2 is a perspective view showing a fire-resistant member combined with a sheet-type outer material of a secondary battery.

[0026] Figure 3 is a drawing for explaining that a sealing line is formed between the space forming part and the side folding part of a sheet-type exterior material.

[0027] FIG. 4 is a plan view showing the side folding portion being fixed to the space forming portion by a fixing member.

[0028] Figure 5 is a diagram illustrating the relationship between the width of the fireproof pad and the short side length of the cap.

[0029] Figure 6 is a diagram illustrating the relationship between the height of the fireproof pad and the width of the fireproof pad.

[0030] 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.

[0031] In order to clearly explain the present invention, detailed descriptions of related prior art that are irrelevant to the explanation or that may 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.

[0032] Furthermore, terms and 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.

[0033] First embodiment

[0034] FIG. 1 is an exploded perspective view of a secondary battery to explain a structure in which an electrode assembly according to the present invention is inserted into the internal space of a sheet-type outer material. FIG. 2 is a perspective view showing a fire-retardant member coupled to a sheet-type outer material of a secondary battery.

[0035] Referring to FIGS. 1 and 2, a secondary battery (10) according to the present invention may include an electrode assembly (100), an internal space (210) that accommodates the electrode assembly (100), a sheet-type exterior material (200) having an exterior material opening (220) that communicates the internal space (210) with the outside, a cap (300) that is inserted into the exterior material opening (220) and seals the internal space (210), and a fire-retardant member (400) made of a flame-retardant material that is bonded to the outer surface of the portion of the sheet-type exterior material (200) that overlaps with the cap (300).

[0036] In this case, a fireproof member (400) composed of a flame-retardant material is attached to the outer surface of the portion of the sheet-type exterior material (200) that overlaps with the cap (300). This prevents the flame from spreading to the cap (300) equipped with the electrode lead (120) even when the flame generated in the internal space (210) containing the electrode assembly (100) is vented to the outside. Therefore, even when a flame is generated inside due to repeated charging and discharging of the secondary battery (10), damage to the electrode lead (120) and the surrounding battery or electronic device connected thereto can be prevented.

[0037] The electrode assembly (100) is a laminate comprising an anode, a cathode, and a separator, and may have various structures. For example, the electrode assembly (100) may be a stack-type electrode assembly in which the anode, cathode, and separator are stacked in one direction, or a stack-folding type electrode assembly in which the anode, cathode, and separator are stacked in one direction and then folded.

[0038] Here, the positive electrode comprises a positive current collector and a positive active material coated on the positive current collector, and the negative electrode may comprise a negative current collector and a negative active material coated on the negative current collector. The separator is a membrane of insulating material interposed between the positive electrode and the negative electrode to block contact between the positive electrode and the negative electrode, and a plurality of pores through which cations pass may be formed in the separator.

[0039] Meanwhile, the sheet-type exterior material (200) may be formed by rolling or folding a laminate sheet (200a) so that one end (201a) and the other end (202a) of the laminate sheet (200a) having a multilayer structure meet each other. At this time, an internal space (210) for accommodating an electrode assembly (100) is formed inside the rolled or folded laminate sheet (200a), and both sides of this internal space (210) may be in communication with the outside.

[0040] Specifically, the laminate sheet (200a) is a sheet having a first end (201a) and a second end (202a) spaced apart from the first end (201a) in a predetermined direction, and the sheet-type exterior material (200) can be formed by rolling or folding the laminate sheet (200a) so that the first end (201a) and the second end (202a) meet. The first end (201a) and the second end (202a) of the laminate sheet (200a) can be joined to each other in various ways. For example, the first end (201a) and the second end (202a) can be bonded with an adhesive, or the first end (201a) and the second end (202a) can be fused to each other by receiving heat and pressure.

[0041] One end (201a) of the laminate sheet (200a) may be joined to the inner or outer surface of the other end (202a). The outer surface of the one end (201a) of the laminate sheet (200a) may be joined to the inner surface of the other end (202a). Additionally, the inner surface of the one end (201a) of the laminate sheet (200a) may be joined to the inner surface of the other end (202a).

[0042] Meanwhile, the laminate sheet (200a) may be a laminate sheet comprising a metal layer such as aluminum or stainless steel. In this case, a resin layer may be formed on the outer surface and the inner surface of the metal layer, respectively.

[0043] 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.

[0044] 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.

[0045] A second resin layer coated on the inner surface of a metal layer can be combined with a cap (300) to seal an internal space (210), 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.

[0046] 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.

[0047] On the other hand, the sheet-type outer material (200) of the secondary battery (10) according to the present invention is formed by rolling or folding a laminate sheet (200a), so that the electrode assembly (100) can be accommodated in the internal space (210) of the sheet-type outer 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 outer material does not apply, the capacity of the secondary battery (10) can be easily increased by increasing the size of the internal space (210). Furthermore, since no portion with reduced thickness is formed in the sheet-type outer material (200) formed by rolling or folding a laminate sheet (200a), defects such as cracks can be prevented in the sheet-type outer material (200).

[0048] For reference, the secondary battery (10) according to the present invention may be formed by placing an electrode assembly (100) on the upper surface of a laminate sheet (200a) in an unfolded state, and then rolling or folding the laminate sheet (200a). Additionally, the secondary battery (10) according to the present invention may be formed by rolling or folding the laminate sheet (200a) to form an internal space (210) and an outer material opening (210), and then inserting the electrode assembly (100) into the outer material opening (210). In both of the above cases, the electrode assembly (100) can be accommodated inside the pouch-type sheet-type outer material (200) without separate cup molding.

[0049] The cap (300) is a member that is inserted into the outer opening (220) to seal the internal space (210) and can be configured in various ways. For example, the cap (300) may be a rectangular box-shaped member, and the cap (300) may have a through hole through which the electrode lead (120) passes and an electrolyte injection port formed therein for injecting the electrolyte into the internal space (210).

[0050] Through this electrolyte injection port, an electrolyte injection process can be performed to inject the electrolyte into the internal space (210) of the secondary battery (10). For example, a user can inject the electrolyte into the internal space (210) through the electrolyte injection port while the secondary battery (10) is positioned so that the cap (300) having the electrolyte injection port is facing upward.

[0051] Additionally, a degassing process can be performed to discharge the gas generated during the activation of the secondary battery (10) to the outside through the electrolyte injection port. For example, the user can open the electrolyte injection port to induce the discharge of gas from the internal space (210).

[0052] After the electrolyte injection process or the degassing process, the internal space (210) can be sealed by sealing or welding the electrolyte injection port. Additionally, it is possible to install an openable valve at the electrolyte injection port so that the electrolyte injection port is opened only when necessary.

[0053] Meanwhile, the cap (300) is composed of a body (310) and a gasket (320) and can block the internal space (210) of the exterior material (200). Specifically, a through hole (311) through which a gas lid (120) passes can be formed in the body (310). The gasket (320) is a member that surrounds the body (310) and can prevent leakage of electrolyte between the exterior material (200) and the body (310). In this case, the gasket (320) may serve as a medium for a solid connection between the exterior material (200) and the body (310).

[0054] These gaskets (320) may have various shapes. For example, the gasket (320) may have a picture frame shape that wraps around the side of the outer surface of the body (310). Additionally, the gasket (320) may be formed to wrap around both the inner and outer surfaces of the body (310).

[0055] Additionally, the gasket (320) may be composed of various materials. In particular, the gasket (320) may be composed of a resin material so that it can be easily fused to the inner surface of a sheet-type outer material (200) composed of a resin material. Specifically, the gasket (320) may use CPP (Casted Polypropylene), chlorinated polypropylene, polyethylene, ethylene-propylene copolymer, polyethylene-acrylic acid copolymer, and polypropylene-acrylic acid copolymer.

[0056] The fire-resistant member (400) is composed of a flame-retardant material and can serve as a member that blocks the propagation of flames to the cap (300) equipped with an electrode lead (120) even when flames generated inside the secondary battery (10) are discharged to the outside of the secondary battery (10). The fire-resistant member (400) made of a flame-retardant material can be attached to the outer surface of the portion of the sheet-type exterior material (200) that overlaps with the cap (300). In this case, even if a part of the sheet-type exterior material (200) is torn or burst and flames are discharged through that part, the fire-resistant member (400) formed on the outer surface of the portion of the sheet-type exterior material (200) that overlaps with the cap (300) can prevent the flames from propagating to the cap (300).

[0057] FIG. 3 is a drawing for explaining that a sealing line is formed between the space-forming part and the side folding part of a sheet-type exterior material. FIG. 4 is a plan view showing the side folding part being fixed to the space-forming part by a fixing member.

[0058] FIG. 3 illustrates a sealing line formed in the boundary area between the space forming portion (201) and the side folding portion (202) of the sheet-type exterior material (200), and FIG. 4 illustrates the side folding portion (202) being fixed while folded toward the space forming portion (201).

[0059] The sheet-type exterior material (200) may include a space-forming portion (201) that forms an internal space (210) as part of a laminate sheet (200a), and a side-folding portion (202) in which one end (201a) and the other end (202a) of the laminate sheet (200a) are folded toward the space-forming portion (201). At this time, the side-folding portion (202) may be folded toward the space-forming portion (201) in a state where the one end (201a) and the other end (202a) of the laminate sheet (200a) meet each other.

[0060] That is, the space forming part (201) is composed of a single layer of laminate sheet (200a), and the laminate sheet (200a) can be overlapped in the side folding part (202). At this time, a sealing line can be formed at the boundary between the space forming part (201) and the side folding part (202). Since heat and pressure are applied to the sheet-type exterior material (200) along the sealing line, the two layers of laminate sheets (200a) constituting the sealing line can be fused together.

[0061] Meanwhile, the secondary battery (10) according to the first embodiment of the present invention may further include a fixing member (500) for fixing the side folding portion (202) so that one side of the side folding portion (202) comes into contact with the space forming portion (201). This fixing member (500) can be configured in various ways. For example, as shown in FIG. 4, the fixing member (500) may be an adhesive tape attached to one end of the side folding portion (202) and the space forming portion (201). Also, although not shown in the drawings, the fixing member (500) may be an adhesive layer formed between one side of the side folding portion (202) and one side of the space forming portion (201).

[0062] The fireproof member (400) can be attached to the outer surface of the portion of the sheet-type exterior material (200) that overlaps with the cap (300). In particular, the fireproof member (400) may be a fireproof pad (400) attached to the outer surface of the portion of the side folding part (202) that overlaps with the cap (300).

[0063] Meanwhile, the side folding portion (202) is configured such that the end portion (201a) and the other end portion (202a) of the laminate sheet (200a) meet each other and are folded toward the space forming portion (201), and a sealing line may be formed between the side folding portion (202) and the space forming portion (201). In the case of a secondary battery (10) having such a structure, as charging and discharging are repeated, the connection of the sealing line between the folding portion (202) and the space forming portion (201) is released, allowing internal gas or flame to be discharged through that part.

[0064] At this time, a fire-retardant member (400) is formed on the outer surface of the part of the side folding portion (202) that overlaps with the cap (300), thereby preventing flames discharged from the side folding portion (202) from propagating to the cap (300). Therefore, even if the secondary battery (10) according to the first embodiment of the present invention is a pouch-type cell equipped with a side folding portion (202), there is an advantageous effect of preventing damage to the electrode lead (120) provided in the cap (300) and the surrounding battery or electronic device connected thereto.

[0065] Figure 5 is a diagram illustrating the relationship between the width of the fireproof pad and the short side length of the cap, and Figure 6 is a diagram illustrating the relationship between the height of the fireproof pad and the width of the fireproof pad.

[0066] Referring to FIGS. 5 and 6, the width (L1) of the fireproof pad (400) may be substantially the same as the short side length (L2) of the cap (300). In this case, the fireproof pad (400) can cover the entire width of the portion of the side folding part (202) that overlaps with the cap (300), thereby having the advantageous effect of blocking flames discharged to the outside through the side folding part (202) from spreading directly to the portion of the cap (300) that is exposed to the outside.

[0067] When the width (L1) of the fireproof pad (400) is substantially the same as the short side length (L2) of the cap (300), the ratio between the height (t1) of the fireproof pad (400) and the width (L1) of the fireproof pad (400) may be 1:5 to 1:20. If the ratio between the height (t1) of the fireproof pad (400) and the width (L1) of the fireproof pad (400) is less than 1:5, the height (t1) of the fireproof pad (400) becomes excessively thick, so the energy density of the secondary battery (10) may be lowered. Additionally, if the ratio between the height (t1) of the fireproof pad (400) and the width (L1) of the fireproof pad (400) exceeds 1:20, the height (t1) of the fireproof pad (400) becomes excessively thin, so the fireproof effect may be lowered.

[0068] Accordingly, the width (L1) of the fireproof pad (400) is substantially the same as the short side length (L2) of the cap (300), and when the ratio between the height (t1) of the fireproof pad (400) and the width (L1) of the fireproof pad (400) is 1:5 to 1:20, the fireproof effect can be reconsidered to prevent the energy density of the secondary battery (10) from becoming excessively low and to block flames emitted to the outside of the secondary battery (10) from reaching the cap (300).

[0069] Additionally, the width (W1) of the fireproof pad (400) may be longer than the width (W2) of the portion where the side folding part (202) and the cap (300) overlap. In this case, the fireproof pad (400) can cover the entire depth-direction length of the portion of the side folding part (202) that overlaps with the cap (300), thereby providing an advantageous effect of blocking flames discharged to the outside through the side folding part (202) from spreading to the joint between the cap (300) and the side folding part (202).

[0070] Meanwhile, as described above, the laminate sheet (200a) is composed of a resin material and may have a three-layer structure consisting of an inner layer that is bonded to the cap (300), a metal layer of a metal material formed on the outer surface of the inner layer, and an outer layer of a resin material formed on the outer surface of the metal layer.

[0071] Additionally, the laminate sheet (200a) is folded or rolled so that the inner layer of the first end (201a) and the inner layer of the other end (202a) meet each other, and these first end and other end (201a, 202a) can be folded toward the space-forming part (201) to form a side folding part (202). That is, the inner layers of the side folding part (202) face each other, and the side of the side folding part (202) that is in contact with the space-forming part (201) may be an outer layer. Additionally, the exposed surface of the side folding part (202) that is exposed to the outside may be an outer layer separate from the side in contact with the space-forming part (201).

[0072] At this time, the fireproof pad (400) may be a polymer pad composed of urethane or silicone material that is heat-fused to the outer surface of the outer layer. That is, the fireproof pad (400) may be heat-fused to the outer layer of the resin material, which is the exposed surface of the side folding part (202) that is exposed to the outside.

[0073] In this way, when the outer layer of the laminate sheet (200a) is composed of a resin layer, the exposed surface of the side folding part (202) that is exposed to the outside can also be a resin layer. Therefore, if the fireproof pad (400) is a polymer pad made of urethane or silicone material, there is an advantageous effect in that the fireproof pad (400) and the side folding part (202) can be easily joined by a heat fusion method.

[0074] 2nd embodiment

[0075] The secondary battery according to the second embodiment of the present invention differs from the first embodiment in that the laminate sheet is a sheet having a two-layer structure, and the fireproof pad is a metal member bonded to the metal layer of the laminate sheet. Hereinafter, common details with 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 details not explained in the second embodiment are necessary, they can be considered as details of the first embodiment.

[0076] In the secondary battery (10) according to the second embodiment of the present invention, the laminate sheet (200a) constituting the sheet-type outer material (200) is composed of a resin material and may be composed of an inner layer that is bonded to a cap (300) and a metal layer made of a metal material formed on the outer surface of the inner layer.

[0077] Specifically, the inner layer is a resin layer that is combined with the cap (300) to seal the internal space (210), and may be composed of a polyolefin-based resin. For example, the inner layer may use CPP (Casted Polypropylene), chlorinated polypropylene, polyethylene, ethylene-propylene copolymer, polyethylene-acrylic acid copolymer, and polypropylene-acrylic acid copolymer.

[0078] 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.

[0079] Meanwhile, the laminate sheet (200a) is folded or rolled so that the inner layer of the first end (201a) and the inner layer of the other end (202a) meet each other, and these first end and other end (201a, 202a) can be folded toward the space-forming part (201) to form a side folding part (202). That is, the inner layers of the side folding part (202) face each other, and one side of the side folding part (202) that is in contact with the space-forming part (201) may be a metal layer. In addition, the exposed surface of the side folding part (202) that is exposed to the outside may be a different metal layer from the one side in contact with the space-forming part (201).

[0080] At this time, the fireproof pad (400) may be a metal pad made of aluminum or stainless steel that is welded to the outer surface of the metal layer. That is, the fireproof pad (400) may be welded to the metal layer, which is the exposed surface of the side folding part (202) that is exposed to the outside.

[0081] In this way, when the outer layer of the laminate sheet (200a) is composed of a metal layer, the exposed surface of the side folding part (202) that is exposed to the outside can also be a metal layer. Therefore, if the fireproof pad (400) is a metal member composed of aluminum or stainless steel, there is an advantageous effect in that the fireproof pad (400) and the side folding part (202) can be easily joined by welding.

[0082] 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.

[0083] [Explanation of the symbol]

[0084] 10: Secondary battery 100: Electrode assembly

[0085] 200: Sheet-type exterior material 201: Space-forming part

[0086] 202: Side folding section 210: Interior space

[0087] 220: Exterior opening 300: Cap

[0088] 310: Body 320: Gasket

[0089] 400: Fireproof member 500: Fixed member

Claims

1. Electrode assembly; A sheet-type exterior material having an internal space accommodating the electrode assembly and an exterior material opening communicating the internal space with the outside; A cap inserted into the opening of the exterior material to seal the interior space; and A secondary battery comprising a fireproof member made of a flame-retardant material bonded to the outer surface of the portion overlapping with the cap among the above sheet-type exterior materials.

2. In Claim 1, The above cap is, A body having a through hole formed through which an electrode lead passes; and A secondary battery comprising a gasket that surrounds the body and is coupled to the inner surface of the sheet-type exterior material.

3. In Claim 1, The above sheet-type exterior material is, A secondary battery formed by rolling or folding a laminate sheet having a multilayer structure such that one end and the other end of the laminate sheet meet each other.

4. In Claim 3, The above sheet-type exterior material is, As a part of the above laminate sheet, a space forming part that forms the internal space; and A secondary battery comprising a side folding portion in which one end and the other end of the above laminate sheet are folded toward the space forming portion.

5. In Claim 4, A secondary battery further comprising a fixing member for fixing the side folding portion such that one side of the side folding portion contacts the space forming portion.

6. In Claim 4, The above fireproof member is, A secondary battery comprising a fireproof pad attached to the outer surface of the portion of the side folding part that overlaps with the cap.

7. In Claim 6, A secondary battery in which the width of the fireproof pad is equal to the short side length of the cap.

8. In Claim 6, A secondary battery in which the ratio between the height of the fireproof pad and the width of the fireproof pad is 1:5 to 1:

20.

9. In Claim 6, A secondary battery in which the width of the fireproof pad is longer than the width of the part where the side folding part and the cap overlap.

10. In Claim 6, The above laminate sheet is, An inner layer composed of a resin material and bonded to the cap; A metal layer of a metal material formed on the outer surface of the inner layer; and A secondary battery comprising an outer layer of resin material formed on the outer surface of the metal layer.

11. In Claim 10, The above fireproof pad is, A secondary battery comprising a polymer pad composed of urethane or silicone material and heat-fused to the outer surface of the outer layer.

12. In Claim 6, The above laminate sheet is, An inner layer composed of a resin material and bonded to the cap; and A secondary battery comprising a metal layer of a metal material formed on the outer surface of the inner layer.

13. In Claim 12, The above fireproof pad is, A secondary battery comprising a metal pad made of aluminum or stainless steel and welded to the outer surface of the metal layer.

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