Gas emission film, secondary battery cartridge, secondary battery, method for manufacturing gas emission film, and method for manufacturing secondary battery cartridge

Abstract

The present invention relates to a gas emission film which has excellent gas emission performance and can be efficiently manufactured. The gas discharge film according to the present invention covers an opening formed in an outer case of a secondary battery and discharges internal gas of the outer case, and comprises: an adhesive layer having adhesiveness due to heat and having a through-hole formed in the adhesive layer; and a permeable layer laminated to one surface of the adhesive layer to cover the through hole and having a higher gas permeability than the adhesive layer, in which the permeable layer may have the same thickness as the adhesive layer or may be formed thicker than the adhesive layer.

Description

Technical Field

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2023-0146958, filed on October 30, 2023, and Korean Patent Application No. 10-2024-0148831, filed on October 28, 2024, the disclosures of which are incorporated herein by reference. Technical Field

[0004] This disclosure relates to a gas emission membrane for discharging internal gases from a secondary battery, a secondary battery box including such a gas emission membrane, and a secondary battery including such a secondary battery box. Background Technology

[0005] Batteries that store electrical energy can generally be divided into primary batteries and secondary batteries. Primary batteries are disposable, while secondary batteries are rechargeable batteries made using materials in which oxidation and reduction processes between current and substrate are repeatable. That is, the power source is charged when a reduction reaction is performed on the material with current, and discharged when an oxidation reaction is performed on the material, and electricity is generated by repeating this charging and discharging process.

[0006] Secondary batteries can be classified according to their shape into cylindrical batteries, pouch batteries, prismatic batteries, etc. Among them, pouch batteries can be manufactured in the following form: an electrode assembly with stacked positive and negative electrodes and separators is housed inside the pouch, and the outer part of the pouch is sealed.

[0007] Simultaneously, the electrolyte can be contained within the pouch of the battery along with the electrode assembly. In this case, residual moisture in the electrolyte or moisture seeping in from the outside can react with the lithium salt inside the pouch to produce hydrogen fluoride (HF), and gases such as carbon dioxide, carbon monoxide, ethylene, and methane can be generated due to the decomposition of the electrolyte. Furthermore, depending on the material of the positive electrode included in the pouch battery's electrode assembly, additional hydrogen and HF may be generated during charging and discharging, potentially leading to overheating due to overcharging and internal short circuits. Therefore, a large amount of gas may be generated inside the pouch. The pressure inside the pouch increases due to this gas, and the increased pressure may cause the pouch to swell or partially rupture, resulting in venting. The pouch battery may include a structure capable of venting the gas inside the pouch to the outside to prevent venting.

[0008] As an example of a structure capable of venting gas from inside the bag to the outside, there exists a structure in which pores are formed in the bag and gas is released through a gas emission membrane. A problem with pouch batteries that include conventional gas emission membranes is that adhesive materials can clog the pores during the manufacturing process, thereby reducing gas emission performance.

[0009] In addition, conventional gas emission membranes are semi-permeable membranes and are attached to bags by thermal fusion. The problem is that when the gas emission membrane is attached, the pores formed in the bag are blocked due to excessive fusion. Summary of the Invention Technical issues

[0010] This disclosure aims to provide a gas emission membrane, a secondary battery case including such a gas emission membrane, and a secondary battery including such a secondary battery case, wherein the gas emission membrane has excellent gas emission performance and can prevent over-fusion when attached to a bag. Technical solution

[0011] According to the present disclosure, a gas emission membrane covers an opening formed in the outer material of a secondary battery and emits internal gas from the outer material. The gas emission membrane may include: an adhesive layer that is thermally adhesive and has through-pores formed therein; and a permeable layer laminated to a surface of the adhesive layer to cover the through-pores and having higher gas permeability than the adhesive layer. The permeable layer may have the same thickness as the adhesive layer or may be formed to be thicker than the adhesive layer.

[0012] The permeable layer and adhesive layer can have a thickness of 10 μm to 100 μm.

[0013] The adhesive layer can be made of any of PE, PP and PPA, and the permeable layer can be made of PTFE material.

[0014] The secondary battery box according to this disclosure may include: an external material element configured to house an electrode assembly and having an opening formed therein; and a gas venting membrane covering the opening formed therein and venting internal gas from the external material element, wherein the gas venting membrane may include an adhesive layer that is thermally adhesive and has through-holes formed therein; and a permeable layer laminated to a surface of the adhesive layer and having higher gas permeability than the adhesive layer, wherein the permeable layer may have the same thickness as the adhesive layer or may be formed to be thicker than the adhesive layer.

[0015] Through holes and openings can overlap each other, and the diameter of the through hole can be larger than the diameter of the opening.

[0016] The center of the through hole and the center of the opening can coincide.

[0017] The diameter of the opening can be from 1mm to 7mm.

[0018] The adhesive layer of the gas emission membrane can be attached to the inner or outer surface of an external material component.

[0019] The external material can be made of a laminated sheet including a resin layer, and the adhesive layer of the gas emission membrane can be made of any of PE, PP and PPA, and can be thermally fused to the resin layer of the laminated sheet.

[0020] The secondary battery according to this disclosure may include: an electrode assembly; an external material element that houses the electrode assembly and has an opening formed therein; and a gas emission membrane that covers the opening formed therein and emits internal gas from the external material element, wherein the gas emission membrane may include: an adhesive layer that is thermally adhesive and has through-pores formed therein; and a permeable layer that is laminated to a surface of the adhesive layer and has higher gas permeability than the adhesive layer, wherein the permeable layer may have the same thickness as the adhesive layer or may be formed to be thicker than the adhesive layer.

[0021] The external material component may include: a cup-shaped portion configured to receive an electrode assembly; a sealing portion forming the outermost part of the external material component and sealing the interior of the external material component; and a platform portion forming the periphery of the cup-shaped portion and disposed between the cup-shaped portion and the sealing portion, wherein an opening may be formed in the platform portion.

[0022] The external material component may include a cup-shaped portion configured to accommodate an electrode assembly, and an opening may be formed on the peripheral surface of the cup-shaped portion.

[0023] The method for manufacturing a gas emission membrane according to the present disclosure may include: a perforation step of forming a plurality of through holes in an adhesive layer that is heat-adhesive; a lamination step of laminating the adhesive layer to have higher gas permeability than the adhesive layer and having the same thickness as the adhesive layer or forming a permeable layer that is thicker than the adhesive layer; and a cutting step of cutting the permeable layer and the adhesive layer into unit membranes having predetermined dimensions, wherein each unit membrane has through holes.

[0024] In the perforation step, multiple through holes can be formed with regular spacing relative to the length and width directions of the adhesive layer.

[0025] During the cutting process, the permeable layer and adhesive layer can be cut at regular intervals relative to the length and width directions of the adhesive layer.

[0026] The method for manufacturing a secondary battery box according to this disclosure may include: a forming step of forming a cup-shaped portion in an outer material to house an electrode assembly; a perforation step of forming an opening in the outer material to which the cup-shaped portion is formed; a lamination step of manufacturing a gas emission membrane by laminating a permeable layer to an adhesive layer, the permeable layer having higher gas permeability than the adhesive layer and having the same thickness as the adhesive layer or being formed to be thicker than the adhesive layer, the adhesive layer being heat-adhesive and having through-holes formed in the adhesive layer; and an attachment step of attaching the gas emission membrane to the outer material to cover the opening.

[0027] The attachment step may include attaching the gas emission membrane to the external material by pressing the gas emission membrane and the external material with a high-temperature sealing device.

[0028] During the application step, the sealing device can press the entire area of ​​the gas emission membrane.

[0029] During the application process, the sealing device can apply heat and pressure to both sides of the gas emission membrane and the external material component.

[0030] The perforation step may include the step of forming an opening on the periphery of a cup-shaped portion formed in an outer material part.

[0031] The perforation step may include the step of forming an opening on the peripheral surface of a cup-shaped portion formed in an outer material part. Beneficial effects

[0032] According to this disclosure, a gas emission membrane covers an opening formed in the external material of a secondary battery and emits internal gases from the external material. The gas emission membrane may include an adhesive layer and a permeable layer. The adhesive layer is thermally bonded and has through-pores formed therein. The permeable layer is laminated to one surface of the adhesive layer to cover the through-pores and has higher gas permeability than the adhesive layer. The permeable layer may have the same thickness as the adhesive layer or may be formed to be thicker than the adhesive layer.

[0033] In this case, the adhesive layer of the external material component that is thermally fused to the secondary battery is formed to be relatively thin, and thus has the beneficial effect of preventing the external material component and the adhesive layer from being over-fused and blocking the opening formed in the external material component.

[0034] Furthermore, the openings formed in the external material are only covered by a gas-permeable layer, and the adhesive layer does not cover the openings, thus having the beneficial effect of effectively venting the internal gases of the secondary battery. Attached Figure Description

[0035] Figure 1This is a perspective view showing the state in which the gas emission membrane according to this disclosure is attached to a secondary battery.

[0036] Figure 2 It is a cross-sectional view used to describe the structure of the gas emission membrane according to this disclosure.

[0037] Figure 3 This is a view used to describe the state in which the gas emission membrane according to this disclosure covers the opening of the secondary battery box.

[0038] Figure 4 This is a perspective view schematically showing an example of a secondary battery according to the present disclosure.

[0039] Figure 5 This is a perspective view schematically showing another example of a secondary battery according to the present disclosure.

[0040] Figure 6 The flowchart schematically illustrates a method for manufacturing a gas emission membrane according to the present disclosure.

[0041] Figure 7 This is a schematic perspective view of a method for manufacturing a gas emission membrane according to the present disclosure, in which the adhesive layer and the permeable layer are laminated.

[0042] Figure 8 This is a perspective view illustrating the process of cutting the adhesive layer and the permeable layer in a method for manufacturing a gas emission membrane according to this disclosure.

[0043] Figure 9 The flowchart schematically illustrates a method for manufacturing a secondary battery box according to the present disclosure. Detailed Implementation

[0044] 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.

[0045] In order to clearly describe this disclosure, irrelevant descriptions or detailed descriptions of related known techniques that may unnecessarily obscure the essential points of this disclosure have been omitted, and throughout this 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.

[0046] Furthermore, 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.

[0047] Gas emission membrane

[0048] Figure 1 This is a perspective view showing the state in which the gas emission membrane according to this disclosure is attached to a secondary battery. Figure 2 It is a cross-sectional view used to describe the structure of the gas emission membrane according to this disclosure. Figure 3 This is a view used to describe the state in which the gas emission membrane according to this disclosure covers the opening of the secondary battery box.

[0049] Reference Figures 1 to 3 According to this disclosure, a gas emission membrane 200 covers an opening 101 formed in the outer material 100 of the secondary battery 10 and emits internal gas from the outer material 100. The gas emission membrane 200 may include an adhesive layer 220 and a permeable layer 210. The adhesive layer 220 is thermally adhesive and has through-holes 221 formed therein. The permeable layer 210 is laminated to one surface of the adhesive layer 220 to cover the through-holes 221 and has higher gas permeability than the adhesive layer 220. Here, the permeable layer 210 may have the same thickness as the adhesive layer 220 or may be formed to be thicker than the adhesive layer 220.

[0050] Here, the adhesive layer 220 can be joined to the external material 100 of the secondary battery 10 by thermal fusion. In the gas emission membrane 200, the thickness of the adhesive layer 220 fused to the external material 100 is formed to be relatively thin, and thus has the beneficial effect of preventing the external material 100 and the adhesive layer 220 from becoming over-fused and blocking the opening 101 formed in the external material 100.

[0051] The thickness d1 of the permeable layer 210 and the thickness d2 of the adhesive layer 220 can be formed in various ways. For example, the thickness d1 of the permeable layer 210 and the thickness d2 of the adhesive layer 220 can each have a value from 10 μm to 100 μm. In this case, the thickness d1 of the permeable layer 210 can be thicker than the thickness d2 of the adhesive layer 220.

[0052] Specifically, the thickness d1 of the permeable layer 210 can be from 60 μm to 100 μm, and the thickness d2 of the adhesive layer 220 can be from 50 μm to 100 μm. Here, the thickness d1 of the permeable layer 210 can be the same as or thicker than the thickness d2 of the adhesive layer 220. For example, when the thickness d1 of the permeable layer 210 is 60 μm, the thickness d2 of the adhesive layer 220 can be 50 μm; when the thickness d1 of the permeable layer 210 is 100 μm, the thickness d2 of the adhesive layer 220 can be 100 μm.

[0053] When the thickness d1 of the permeable layer 210 is less than or equal to 60 μm, the thickness d1 of the permeable layer 210 becomes relatively thin, and therefore the electrolyte contained inside the outer material 100 can leak to the outside through the permeable layer 210.

[0054] Furthermore, when the thickness d1 of the permeable layer 210 is greater than or equal to 1000 μm, the thickness d1 of the permeable layer 210 becomes thicker, and therefore the gas permeability of the internal gas passing through the external material 100 of the permeable layer 210 may decrease. Therefore, it may be suitable to form the thickness d1 of the permeable layer 210 to be 60 μm to 100 μm.

[0055] When the thickness d2 of the adhesive layer 220 is less than or equal to 50 μm, the adhesive layer 220 can be formed thin, and therefore the bonding force between the adhesive layer 220 and the external material 100 may be reduced. Furthermore, when the thickness d2 of the adhesive layer 220 is greater than or equal to 100 μm, the adhesive layer 220 may be over-fused to the external material 100, thereby blocking the opening 101 formed in the external material 100 or damaging the external material 100. Therefore, it may be suitable to form the thickness d2 of the adhesive layer 220 to be between 50 μm and 100 μm.

[0056] Meanwhile, the permeable layer 210 and the adhesive layer 220 can be joined in various ways. For example, the permeable layer 210 and the adhesive layer 220 can each be surface-treated with plasma and then thermally fused together in an overlapping state.

[0057] The permeable layer 210 of the gas emission membrane 200 can be configured to cover the opening 101 of the outer material component 100. In addition, an adhesive layer 220 can be disposed between the outer material component 100 and the permeable layer 210 to bond the outer material component 100 and the permeable layer 210.

[0058] The adhesive layer 220 of the gas emission membrane 200 may include a material that is thermally adhesive. Thermally adhesive materials include polyethylene (PE), polypropylene (PP), and polypropylene grafted maleic anhydride (PPA). Therefore, the adhesive layer 220 may include at least one of PE, PP, and PPA.

[0059] Additionally, as an example of a structure for improving gas emission performance, through-holes 221 can be formed in the adhesive layer 220 of the gas emission membrane 200. Since the through-holes 221 overlap with the openings 101 formed in the outer material 100, the internal gas of the outer material 100 can be discharged to the outside through the openings 101 and the through-holes 221, through the permeable layer 210.

[0060] Furthermore, the permeable layer 210 of the gas emission membrane 200 according to this disclosure can have a cross-section with an approximately rectangular shape. This is merely an example, and the permeable layer 210 can have cross-sections of different shapes.

[0061] The permeable layer 210 of the gas emission membrane 200 is attached to the outer material 100 to cover the opening 101 formed in the outer material 100 and to allow the passage of internal gas in the outer material 100. Specifically, gas generated inside the outer material 100 can be discharged to the outside of the outer material 100 through the opening 101 and then through the permeable layer 210.

[0062] The permeable layer 210 of the gas emission membrane 200 can have higher gas permeability than the outer material 100. Furthermore, the permeable layer 210 can include a material that allows gas to escape but not liquid to pass through. For example, the permeable layer 210 of the gas emission membrane 200 can include a fluoropolymer resin.

[0063] Specifically, the permeable layer 210 can be made of polytetrafluoroethylene (PTFE). In this case, the electrolyte disposed inside the outer material 100 can bypass the permeable layer 210, but the gas generated inside the outer material 100 can pass through the permeable layer 210.

[0064] exist Figure 3 In the diagram, the adhesive layer 220 and the through-hole 221 are shown as circular, but this is only an example. That is, the adhesive layer 220 can be arranged in different shapes to bond the permeable layer 210 and the outer material part 100. In addition, the through-hole 221 can also be formed in different shapes.

[0065] Simultaneously, the gas emission membrane 200 is joined to the external material component 100 of the secondary battery 10 by a thermal fusion method, and the portion of the adhesive layer 220 that melts due to heat does not block the opening 101 of the external material component 100. Specifically, the diameter t2 of the through hole 221 formed in the adhesive layer 220 is larger than the diameter t1 of the opening 101 formed in the external material component 100, and therefore, even when a portion of the adhesive layer 220 melts due to heat, it can flow downward to the upper region of the opening 101 and harden again in the upper region of the opening 101.

[0066] Therefore, even when the gas emission membrane 200 and the outer material 100 are thermally fused together, the opening 101 of the outer material 100 will not be blocked, and thus the internal gas of the outer material 100 can be emitted more effectively.

[0067] Secondary battery box

[0068] Figure 1 An example of a secondary battery 10 according to the present disclosure is shown, and a secondary battery case in which electrode components and electrolyte are housed is also shown.

[0069] Reference Figure 1 The secondary battery box according to this disclosure may include an outer material component 100 and a gas emission membrane 200. The outer material component 100 is configured to accommodate an electrode assembly and has an opening 101 formed therein. The gas emission membrane 200 covers the opening 101 formed therein and discharges internal gas from the outer material component 100. In other words, the secondary battery box may have a structure in which the gas emission membrane 200 is coupled to the outer material component 100 in which the opening 101 is formed.

[0070] The gas emission membrane 200 may include an adhesive layer 220 and a permeable layer 210. The adhesive layer 220 is thermally adhesive and has through-holes 221 formed therein. The permeable layer 210 is laminated to one surface of the adhesive layer 220 and has higher gas permeability than the adhesive layer 220. The permeable layer 210 may have the same thickness as the adhesive layer 220 or may be formed to be thicker than the adhesive layer 220.

[0071] In this case, the opening 101 formed in the outer material 100 is only covered by the gas-permeable layer 210, and the adhesive layer 220 does not cover the opening 101, thus having the beneficial effect of effectively venting the internal gas of the housing 100.

[0072] Furthermore, the adhesive layer 220 can be bonded to the external material 100 of the secondary battery 10 by thermal fusion. In the gas emission membrane 200, the thickness of the adhesive layer 220 fused to the external material 100 is formed to be relatively thin, and thus has the beneficial effect of preventing the external material 100 and the adhesive layer 220 from becoming over-fused and blocking the opening 101 formed in the external material 100.

[0073] Meanwhile, the through hole 221 and the opening 101 overlap each other, and the diameter t2 of the through hole 221 can be larger than the diameter t1 of the opening 101. Here, the area of ​​the through hole 221 can be formed to be wider than the area of ​​the opening 101.

[0074] Specifically, the center of the through hole 221 and the center of the opening 101 can coincide with each other, and the entire area of ​​the opening 101 can be included inside the through hole 221. In particular, the diameter t2 of the through hole 221 can be approximately 0 mm to 4 mm larger than the diameter t1 of the opening 101.

[0075] When the diameter t2 of the through hole 221 is smaller than the diameter t1 of the opening 101, a portion of the opening 101 is blocked by the adhesive layer 220, and therefore the gas emission efficiency may decrease. Furthermore, when the diameter t2 of the through hole 221 is excessively larger than the diameter t1 of the opening 101, the adhesive force of the adhesive layer 220 may decrease.

[0076] Therefore, the diameter t2 of the through hole 221 should be appropriately formed, and when the diameter t2 of the through hole 221 is about 0 mm to 4 mm larger than the diameter t1 of the opening 101, the gas emission efficiency can be reconsidered and the high adhesion of the adhesive layer 220 can be maintained.

[0077] For example, when the diameter t1 of the circular opening 101 is approximately 4.5 mm or larger and 5.5 mm or smaller, the diameter t2 of the circular through-hole 221 can be approximately 6.5 mm or larger and 7.5 mm or smaller. Furthermore, when the diameter t1 of the circular opening 101 is approximately 5 mm, the diameter t2 of the circular through-hole 221 can be approximately 5 mm or larger and 9 mm or smaller.

[0078] Furthermore, the diameter t1 of the opening 101 can have a value greater than or equal to 1 mm and less than or equal to 7 mm. In this case, the diameter t2 of the through hole 221 can be approximately 0 mm to 4 mm larger than the diameter t1 of the opening 101. That is, the diameter t2 of the through hole 221 can have a value greater than or equal to 1 mm and less than or equal to 11 mm.

[0079] The external material 100 is made of a laminated sheet including a resin layer, and the adhesive layer 220 of the gas emission membrane 200 can be made of any of PE, PP, and PPA. In this case, the adhesive layer 220 can be thermally fused to the resin layer of the laminated sheet.

[0080] Specifically, the outer material component 100 may include an inner layer, a metal layer, and an outer layer, wherein the inner layer can have sealing properties through heat and pressure. The outer material component 100 houses the electrode assembly, and the inner layer of the outer material component 100 can then be sealed through heat and pressure. The metal layer may primarily be AL, STS, etc. Furthermore, the outer layer may have insulating properties.

[0081] The inner layer, capable of sealing the outer material component 100 by means of a seal, may be made of one or more materials selected from the following: polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyarylate, Teflon, and glass fiber. In particular, polyolefin-based resins, such as polypropylene (PP) or polyethylene (PE), may be used primarily.

[0082] Meanwhile, the adhesive layer 220 of the gas emission membrane 200 can be attached to the inner or outer surface of the outer material component 100. That is, the gas emission membrane 200 can be contained inside the outer material component 100 or exposed to the outside of the outer material component 100. When the gas emission membrane 200 is disposed on the inner surface of the outer material component 100, gas generated inside the outer material component 100 can be discharged to the outside of the outer material component 100 through the permeable layer 210 and then through the opening 101.

[0083] Preferably, considering factors such as moisture penetration and ease of manufacturing, the gas emission membrane 200 can be disposed on the outer surface of the outer material component 100. Specifically, the gas emission membrane 200 can be disposed on the platform portion 120 of the outer material component 100. That is, the opening 101 of the outer material component 100 can be formed on the platform portion 120. As described above, the platform portion 120 of the outer material component 100 forms the periphery of the cup-shaped portion 110 and can be disposed between the cup-shaped portion 110 and the sealing portion 130.

[0084] Since the sealing portion 130 of the external material component 100 is sealed with a sealant on the opposing surface, the gas emission performance may be reduced when the gas emission membrane 200 is disposed on the sealing portion 130. Therefore, in order to prevent the gas emission performance of the gas emission membrane 200 from being reduced, the gas emission membrane 200 may be disposed on the platform portion 120. In addition, the gas emission membrane 200 may be disposed separately from the electrode assembly so that the internal gas of the external material component 100 can be more effectively discharged to the outside through the opening 101.

[0085] Secondary batteries

[0086] Figure 1 A secondary battery according to an embodiment of the present disclosure is shown.

[0087] Reference Figure 1 The secondary battery 10 according to an embodiment of the present disclosure may include an electrode assembly, an external material 100 housing the electrode assembly and having an opening 101 formed therein, and a gas emission membrane 200 covering the opening 101 formed in the external material 100 and venting internal gas from the external material 100. In this case, the gas emission membrane 200 may include an adhesive layer 220 and a permeable layer 210. The adhesive layer 220 is thermally adhesive and has through-holes 221 formed therein. The permeable layer 210 is laminated to one surface of the adhesive layer 220 and has higher gas permeability than the adhesive layer 220. The permeable layer 210 may have the same thickness as the adhesive layer 220 or may be formed to be thicker than the adhesive layer 220.

[0088] In this case, the opening 101 formed in the outer material 100 is only covered by the gas-permeable layer 210, and the adhesive layer 220 does not cover the opening 101, thereby having the beneficial effect of effectively discharging the internal gas of the secondary battery 10.

[0089] Furthermore, the adhesive layer 220 can be bonded to the external material 100 of the secondary battery 10 by thermal fusion. In the gas emission membrane 200, the thickness of the adhesive layer 220 fused to the external material 100 is formed to be relatively thin, and thus has the beneficial effect of preventing the external material 100 and the adhesive layer 220 from becoming over-fused and blocking the opening 101 formed in the external material 100.

[0090] The secondary battery 10 may include an electrode assembly (not shown), an external material component 100, and a gas emission membrane 200. The secondary battery 10 may refer to a secondary battery including an external material component 100 capable of changing shape in various forms of rechargeable and dischargeable secondary batteries. That is, the external material component 100 may be a pouch-type external material component made of laminated sheets.

[0091] The electrode assembly of the secondary battery 10 may include a positive electrode, a negative electrode, and a separator. Here, the separator may be disposed between the positive and negative electrodes to physically separate them. The electrode assembly may be in the form of a stacked positive electrode, a negative electrode, and a separator, or in the form of a wound positive electrode, a negative electrode, and a separator.

[0092] The secondary battery 10 may include electrode leads. The electrode leads may be electrically connected to an electrode assembly and are configured to protrude outwards from the outer material member 100. The secondary battery 10 can supply electrical energy to the outside via the electrode leads protruding outwards from the outer material member 100. Therefore, the electrode leads may be conductors.

[0093] The lead film can cover the electrode leads, thereby insulating the external material 100 and the electrode leads from each other. Specifically, the lead film can be disposed on both surfaces of the electrode leads to cover them. The lead films can be constructed in pairs and can be disposed on the two surfaces of the electrode leads respectively.

[0094] The external material component 100 may include a cup-shaped portion 110 configured to accommodate an electrode assembly, a sealing portion 130 forming the outermost portion of the external material component 100 and sealing its interior, and a platform portion 120 forming the periphery of the cup-shaped portion 110 and disposed between the cup-shaped portion 110 and the sealing portion 130.

[0095] Here, the cup-shaped portion 110 of the outer material 100 can refer to the portion formed by molding the bag film to create a space for accommodating the electrode assembly. The sealing portion 130 can refer to the portion forming the outermost portion of the outer material 100, which is sealed by heat and pressure. Furthermore, the platform portion 120 forms the periphery of the cup-shaped portion 110 and can be disposed between the cup-shaped portion 110 and the sealing portion 130. Specifically, at the periphery of the cup-shaped portion 110 other than the cup-shaped portion 110, the portion sealed by sealing can be the sealing portion 130, and another portion can be the platform portion 120.

[0096] The sealing portion 130 may include a portion of the electrode leads that protrude. The portion of the electrode leads of the sealing portion 130 may be sealed with a lead film. In addition, the facing external material parts 100 may seal each other at the portions of the sealing portion 130 where the electrode leads do not protrude.

[0097] Meanwhile, when the secondary battery 10 is repeatedly charged and discharged, gas is generated, which can increase the pressure inside the external material component 100. If the pressure inside the external material component 100 increases excessively, venting may occur, and the secondary battery 10 may therefore lose its function.

[0098] Specifically, the electrolyte can be contained within the external material component 100 of the secondary battery 10 along with the electrode assembly. In this case, residual moisture in the electrolyte or moisture seeping in from the outside can react with the lithium salt inside the external material component 100 to produce HF, and gases such as carbon dioxide, carbon monoxide, ethylene, and methane can be generated due to the decomposition of the electrolyte. Furthermore, depending on the material of the positive electrode included in the electrode assembly of the secondary battery 10, hydrogen and HF may be additionally generated during charging and discharging, which could lead to overheating due to overcharging and internal short circuits. Therefore, a large amount of gas may be generated inside the external material component 100. The pressure inside the external material component increases due to this gas, and the increased pressure may cause expansion of the external material component 100 or venting due to the rupture of a portion of the external material component 100.

[0099] The secondary battery 10 according to this disclosure may include a structure capable of venting gas inside the external material 100 to the outside of the external material 100 to prevent venting from occurring.

[0100] As an example of a configuration capable of venting gas inside the external material component 100 to the outside of the external material component 100, an opening 101 may be formed in a portion of the external material component 100 of the secondary battery 10. Furthermore, the secondary battery 10 may include a gas emission membrane 200 disposed in the portion of the external material component 100 in which the opening 101 is formed.

[0101] Reference Figure 1 The opening 101 formed in the outer material 100 may have a generally circular cross-section. This is just one example, and the opening 101 may be formed in different shapes. Furthermore, multiple openings 101 may be formed in the outer material 100.

[0102] at the same time, Figure 4 This is a perspective view schematically showing another embodiment of the secondary battery according to the present disclosure. Figure 4 The secondary battery shown can differ in the arrangement of the gas emission membrane. Figure 1 The secondary battery shown.

[0103] Reference Figure 4 The gas emission membrane 200 of the secondary battery 10 can be disposed in the cup-shaped portion 110 of the outer material member 100. In this respect, the outer material member 100 may include a cup-shaped portion 110 formed into a concave shape for the arrangement of electrode assemblies. The cup-shaped portion 110 may include a surface for housing the electrode assemblies and a peripheral surface bent at that surface to form a boundary. Here, the gas emission membrane 200 may be disposed on the peripheral surface forming the boundary of the cup-shaped portion 110.

[0104] In this respect, when multiple secondary batteries 10 are used to manufacture a battery module, the secondary batteries 10 can be stacked side by side. At this time, the multiple secondary batteries 10 can be arranged with one surface of the cup-shaped portion 110 in contact with each other. Specifically, the surface of adjacent secondary batteries 10 in contact with each other can be the surface with the largest area in the cup-shaped portion 110 where the electrode assembly is placed. Therefore, when the gas emission membrane 200 is disposed on the surface of the cup-shaped portion 110 where the electrode assembly is placed, the gas emission efficiency may be reduced. That is, in the secondary battery 10 according to this disclosure, the gas emission membrane 200 is disposed on the peripheral surface of the cup-shaped portion 110, so that even when the secondary batteries 10 are stacked to manufacture a battery module, gas can be emitted more efficiently.

[0105] at the same time, Figure 4 The secondary battery 10 shown may include a plurality of gas emission membranes 200. Here, each of the gas emission membranes 200 may be disposed at a different position on the peripheral surface of the cup-shaped portion 110. Because the secondary battery 10 includes a plurality of gas emission membranes 200, gas inside the external material component 100 can be effectively released.

[0106] Figure 5 This is a perspective view schematically showing another embodiment of the secondary battery according to the present disclosure. Figure 5 The secondary battery shown is Figure 1 and Figure 4 The secondary battery shown has differences in the shape of its external material components.

[0107] Reference Figure 5 The secondary battery 10' may include an outer material component 100' surrounding the electrode assembly. That is, the outer material component 100' of the secondary battery 10' may be configured to surround the side surfaces of the electrode assembly and may be connected to caps 300 located at both ends of the electrode assembly. Here, the outer material component 100' and the caps 300 may be connected by means of sealing or the like.

[0108] Specifically, one end and the other end of the outer material piece 100' surrounding the side surface of the electrode assembly can be connected by means of sealing or the like. Furthermore, one end and the other end of the electrode assembly not covered by the outer material piece 100' can be covered by a cover 300.

[0109] Reference Figure 5The gas emission membrane 200 can be disposed on one surface of the outer material component 100'. Specifically, the gas emission membrane 200 can be disposed on the outer surface of the outer material component 100'. The gas emission membrane 200 can be disposed on both the inner and outer surfaces of the outer material component 100'. Preferably, considering gas emission efficiency, ease of manufacturing, etc., the gas emission membrane 200 can be disposed on the outer surface of the outer material component 100'. Therefore, the gas generated inside the outer material component 100' and the cover 300 can be effectively discharged to the outside.

[0110] The adhesive layer 220 of the gas emission membrane 200 includes through-holes 221, which have a larger area than the pores formed in the outer material member 100'. Figure 1 and Figure 4 The case is the same for the secondary battery 10 shown.

[0111] Figure 5 The shape of the secondary battery 10' shown is merely an example. The location and number of external material components 100' can vary within the range necessary to demonstrate the effects of this disclosure. Although not described in detail in this disclosure, the secondary battery 10' may also include a gas removal member formed in the cover 300.

[0112] Method for manufacturing gas emission membranes

[0113] The method for manufacturing a gas emission membrane according to this disclosure can refer to a method for manufacturing a unit membrane 1300 connected to an external material component 100 for venting gas inside the external material component 100. That is, the unit membrane 1300 manufactured by the method for manufacturing a gas emission membrane can be used to manufacture a secondary battery 10. Furthermore, the unit membrane 1300 connected to the external material component 100 through a process such as sealing can become a gas emission membrane 200.

[0114] Figure 6 The flowchart schematically illustrates a method for manufacturing a gas emission membrane according to the present disclosure. Figure 7 This is a schematic perspective view of a method for manufacturing a gas emission membrane according to the present disclosure, in which the adhesive layer and the permeable layer are laminated. Figure 8 This is a perspective view illustrating the process of cutting the adhesive layer and the permeable layer in a method for manufacturing a gas emission membrane according to this disclosure.

[0115] Reference Figures 6 to 8The method for manufacturing a gas emission membrane according to the present disclosure may include: a perforation step S11 of forming a plurality of through holes 221 in an adhesive layer 1100 that has adhesiveness by heat; a lamination step S12 of laminating the adhesive layer 220 to a permeable layer 1200, the permeable layer 1200 having higher gas permeability than the adhesive layer 1100 and having the same thickness as the adhesive layer 1100 or being formed to be thicker than the adhesive layer 1100; and a cutting step S13 of cutting the permeable layer 1200 and the adhesive layer 1100 into unit membranes having a predetermined size, wherein each unit membrane has a through hole 221.

[0116] In this case, the opening 101 formed in the outer material 100 is only covered by the gas-permeable layer 210, and the adhesive layer 220 does not cover the opening 101, so that the gas emission membrane 200 manufactured by the above manufacturing method has the beneficial effect of effectively venting the internal gas of the secondary battery 10.

[0117] Furthermore, the adhesive layer 220 can be joined to the external material component 100 of the secondary battery 10 by thermal fusion. In the gas emission membrane 200, the thickness of the adhesive layer 220 fused to the external material component 100 is formed to be relatively thin, and therefore, when the gas emission membrane 200 is fused to the external material component 100, it has the beneficial effect of preventing the external material component 100 and the adhesive layer 220 from becoming over-fused and blocking the opening 101 formed in the external material component 100.

[0118] In the perforation step S11, a plurality of through holes 221 can be formed in the adhesive layer 1100, which becomes adhesive through heat. At this time, the through holes 221 can have a shape that penetrates from one surface of the adhesive layer 1100 to another surface, and can have an approximately circular cross-section. However, the cross-sectional shape of the through holes 221 can vary.

[0119] In the perforation step S11, the plurality of through holes 221 can be formed with regular spacing between them relative to the longitudinal and width directions of the adhesive layer 1100. Therefore, unit films 1300 of the same size can be efficiently manufactured by the cutting step S13, which will be described later.

[0120] Reference Figure 7 In lamination step S12, the adhesive layer 1100 can be laminated together with a permeable layer 1200 that has higher gas permeability than the adhesive layer 1100. Here, the adhesive layer 1100 can be in a state where the through-hole 221 is perforated. Furthermore, the overall shape of the adhesive layer 1100 can be approximately similar to the overall shape of the permeable layer 1200. Therefore, the permeable layer 1200 can be configured to cover the adhesive layer 1100.

[0121] Reference Figure 8In the cutting step S13, the adhesive layer 1100, to which the permeable layer 1200 is laminated, can be cut into unit membranes 1300 with a preset size. Here, the adhesive layer 1100 laminated to the permeable layer 1200 can be cut so that each unit membrane 1300 has a through hole 221.

[0122] Simultaneously, in the cutting step S13, the adhesive layer 1100, on which the permeable layer 1200 is laminated, can be cut at regular intervals relative to the length and width directions of the adhesive layer 1100. Therefore, each unit membrane 1300 can have the same shape and include through holes 221. That is, unit membranes 1300 of the same size can be efficiently manufactured through the cutting step S13.

[0123] In other words, the method for manufacturing gas emission membranes according to this disclosure can manufacture multiple unit membranes 1300 with the same shape in one cycle. Therefore, the efficiency and economy of the manufacturing process can be improved.

[0124] Method for manufacturing secondary battery boxes

[0125] Figure 9 The flowchart schematically illustrates a method for manufacturing a secondary battery box according to the present disclosure.

[0126] Reference Figure 9 The method for manufacturing a secondary battery box according to the present disclosure may include: a forming step S21 of forming a cup-shaped portion 110 in an outer material 100 to accommodate an electrode assembly; a perforation step S22 of forming an opening 101 in the outer material 100 to which the cup-shaped portion 110 is formed; a lamination step S23 of manufacturing a gas emission membrane 200 by laminating a permeable layer 210 to an adhesive layer 220, wherein the permeable layer 210 has higher gas permeability than the adhesive layer 220 and has the same thickness as the adhesive layer 220 or is formed to be thicker than the adhesive layer 220, the adhesive layer is thermally adhesive and has a through-hole 221 formed therein; and an attachment step S24 of attaching the gas emission membrane 200 to the outer material 100 to cover the opening 101.

[0127] In this case, the opening 101 formed in the outer material 100 is only covered by the gas-permeable layer 210, and the adhesive layer 220 does not cover the opening 101, so that the secondary battery box manufactured by the above manufacturing method has the beneficial effect of effectively discharging the internal gas through the gas emission membrane 200.

[0128] Furthermore, the adhesive layer 220 can be joined to the external material component 100 of the secondary battery 10 by thermal fusion. In the gas emission membrane 200, the thickness of the adhesive layer 220 fused to the external material component 100 is formed to be relatively thin, and therefore, when the gas emission membrane 200 is fused to the external material component 100, it has the beneficial effect of preventing the external material component 100 and the adhesive layer 220 from becoming over-fused and blocking the opening 101 formed in the external material component 100.

[0129] In the secondary battery case according to this disclosure, a form in which a space for accommodating electrode components is formed by molding is described as an example. That is, the secondary battery case can refer to the outer material part of a pouch-type secondary battery. Therefore, in the molding step S21 of the method for manufacturing the secondary battery case, the cup-shaped portion 110 can be formed on the pouch film. For example, the punch of the molding apparatus can press the pouch film to form the cup-shaped portion 110.

[0130] After the forming step S21, the perforation step S22 can be performed. In the perforation step S22, an opening 101 can be formed on the bag film with the cup-shaped portion 110 formed. Here, the method of forming the opening 101 can vary. The opening 101 can have a shape that penetrates from one surface of the bag film to another surface, and can have an approximately circular cross-section. However, the cross-sectional shape of the opening 101 can vary.

[0131] In the perforation step S22, the location where the opening 101 is formed can vary depending on the shape of the manufactured secondary battery box. For example, the opening 101 can be formed on the periphery of the cup-shaped portion 110 formed in the bag film, or it can be formed on the peripheral surface of the cup-shaped portion 110 formed in the bag film.

[0132] After the perforation step S22, the lamination step S23 can be performed. In the lamination step S23, the gas emission membrane 200 can be manufactured by laminating an adhesive layer 220 in which the through-holes 221 are formed and a permeable layer 210 that allows gas to pass through. That is, the gas emission membrane 200 manufactured by the lamination step S23 may include the adhesive layer 220 and the permeable layer 210.

[0133] In lamination step S23, the permeable layer 210 and the adhesive layer 220 can be joined in various ways. For example, the permeable layer 210 and the adhesive layer 220 can each be surface-treated with plasma and then thermally fused together in an overlapping state.

[0134] In the method for manufacturing a secondary battery box according to this disclosure, the case where the lamination step S23 is performed after the perforation step S22 is described as an example (see [link]). Figure 9 However, the perforation step S22 and the lamination step S23 can be performed in reverse order.

[0135] Furthermore, in the method for manufacturing a secondary battery box according to this disclosure, the area of ​​the through hole 221 can be formed to be wider than the area of ​​the opening 101. Therefore, it is possible to prevent the adhesive layer 220 from blocking the opening 101 during the manufacturing process.

[0136] After lamination step S23, attachment step S24 can be performed. In attachment step S24, the gas emission membrane 200 can be attached to a portion of the opening 101 forming the bag membrane. That is, the opening 101 can be covered by the gas emission membrane 200.

[0137] For example, in the application step S24, the gas emission membrane 200 can be applied to the bag film by heat. Specifically, the application step S24 can be a step of applying the gas emission membrane 200 to the outer material 100 by pressing the gas emission membrane 200 and the outer material 100 with a high-temperature sealing device.

[0138] In other words, the gas emission membrane 200 can be attached to the bag film by sealing with a sealing device. A portion of the adhesive layer 220 can be melted by heat to become adhesive, and the gas emission membrane 200 can be attached to the bag film by the adhesiveness of the adhesive layer 220.

[0139] Meanwhile, in the application step S24, the sealing device can press the entire area of ​​the gas emission membrane 200.

[0140] Conventionally, the adhesive layer 220 is provided in the form of covering the opening 101. In this case, when the sealing device applies heat to the entire area of ​​the gas emission membrane 200, the portion of the adhesive layer 220 covering the opening 101 may melt due to the heat. That is, the portion of the adhesive layer 220 that melts due to heat may block the opening 101 or cause defects on the outer surface of the opening 101. Therefore, conventionally, the sealing device may only apply heat to the portion corresponding to the shape of the opening 101. Therefore, high precision is required during the application process, and defects are therefore likely to occur.

[0141] On the other hand, in the method for manufacturing a secondary battery box according to this disclosure, a through-hole 221 is formed in the adhesive layer 220, and the area of ​​the through-hole 221 can be larger than the area of ​​the opening 101. That is, the adhesive layer 220 does not cover any part of the opening 101, and therefore, even if the sealing device seals the entire area of ​​the gas emission membrane 200, the possibility of defects can be significantly reduced. Therefore, the efficiency of the process can be improved.

[0142] In addition, in the application step S24, the sealing device can apply heat and pressure to both sides of the gas emission membrane 200 and the external material 100.

[0143] Conventionally, the adhesive layer 220 is provided in the form of covering the opening 101. In this case, when the sealing device applies heat to the bag film, the heat can be applied directly to the adhesive layer 220 covering the opening 101 through the opening 101. Therefore, a portion of the adhesive layer 220 may melt due to heat, and defects are likely to occur in this process, such as a portion of the melted adhesive layer 220 blocking the opening 101. Furthermore, the sealing device only applies heat to the gas emission membrane 200, which may cause the adhesive strength of the gas emission membrane 200 to weaken.

[0144] On the other hand, in the method for manufacturing a secondary battery box according to this disclosure, a through-hole 221 is formed in the adhesive layer 220, and the area of ​​the through-hole 221 can be larger than the area of ​​the opening 101. That is, the adhesive layer 220 does not cover the opening 101. Therefore, even if the sealing device applies heat to the bag film, the possibility that the molten adhesive layer 220 will move to the position where the opening 101 is formed can be reduced. In other words, the possibility of defects occurring during the process can be significantly reduced. Therefore, the efficiency of the process can be improved.

[0145] 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.

[0146] [List of reference numerals]

[0147] 10, 10': Secondary battery; 100, 100': External material components.

[0148] 101: Opening 110: Cup-shaped portion

[0149] 120: Platform section; 130: Sealing section

[0150] 200: Gas emission membrane; 210: Permeable layer

[0151] 220: Adhesive layer; 221: Through-hole

[0152] 300: Cover 1100: Adhesive layer

[0153] 1200: Permeable layer; 1300: Unit membrane

Claims

1. A gas emission membrane covering an opening formed in an external material of a secondary battery and emitting internal gas from the external material, the gas emission membrane comprising: An adhesive layer that becomes adhesive by heat and has through-holes formed therein; as well as A permeable layer, laminated to one surface of the adhesive layer to cover the through-holes, and having higher gas permeability than the adhesive layer. The permeable layer has the same thickness as the adhesive layer or is formed to be thicker than the adhesive layer.

2. The gas emission membrane according to claim 1, in, The permeable layer and the adhesive layer have a thickness of 10 μm to 100 μm.

3. The gas emission membrane according to claim 1, in, The adhesive layer is made of any one of polyethylene, polypropylene, and polypropylene grafted with maleic anhydride, and The permeable layer is made of polytetrafluoroethylene.

4. A secondary battery box, comprising: An external material component, the external material component being configured to accommodate an electrode assembly and having an opening formed in the external material component; as well as A gas emission membrane covers the opening formed in the outer material and emits internal gases from the outer material. The gas emission membrane includes: An adhesive layer, which becomes adhesive by heat and has through-holes formed therein; and A permeable layer, laminated to one surface of the adhesive layer and having higher gas permeability than the adhesive layer, The permeable layer has the same thickness as the adhesive layer or is formed to be thicker than the adhesive layer.

5. The secondary battery box according to claim 4, in, The through hole and the opening overlap each other, and the diameter of the through hole is larger than the diameter of the opening.

6. The secondary battery box according to claim 4, in, The center of the through hole and the center of the opening coincide with each other.

7. The secondary battery box according to claim 6, in, The diameter of the opening is 1 mm to 7 mm.

8. The secondary battery box according to claim 4, in, The adhesive layer of the gas emission membrane is attached to the inner or outer surface of the external material component.

9. The secondary battery box according to claim 5, in, The external material component is composed of a laminated sheet including a resin layer, and The adhesive layer of the gas emission membrane is made of any one of polyethylene, polypropylene, or polypropylene grafted with maleic anhydride, and is thermally fused to the resin layer of the laminated sheet.

10. A secondary battery, comprising: Electrode assembly; An external material component that houses the electrode assembly and has an opening formed therein; as well as A gas emission membrane covers the opening formed in the outer material and emits internal gases from the outer material. The gas emission membrane includes: An adhesive layer, which becomes adhesive by heat and has through-holes formed therein; and A permeable layer, laminated to one surface of the adhesive layer and having higher gas permeability than the adhesive layer, The permeable layer has the same thickness as the adhesive layer or is formed to be thicker than the adhesive layer.

11. The secondary battery according to claim 10, in, The external material component includes: A cup-shaped portion, the cup-shaped portion being configured to accommodate the electrode assembly; A sealing portion, the sealing portion forming the outermost portion of the outer material member and sealing the interior of the outer material member; and The platform portion forms the periphery of the cup-shaped portion and is disposed between the cup-shaped portion and the sealing portion. The opening is formed in the platform portion.

12. The secondary battery according to claim 10, in, The external material component includes a cup-shaped portion configured to accommodate the electrode assembly, and The opening is formed on the peripheral surface of the cup-shaped portion.

13. A method for manufacturing a gas emission membrane, comprising: A perforation step that forms multiple through-holes in a heat-adhesive adhesive layer; The lamination step involves laminating the adhesive layer to a degree that is more gas-permeable than the adhesive layer and has the same thickness as the adhesive layer, or forming a permeable layer that is thicker than the adhesive layer. as well as The cutting step involves cutting the permeable layer and the adhesive layer into unit membranes of a predetermined size, wherein each unit membrane has the through-hole.

14. The method for manufacturing a gas emission membrane according to claim 13, in, In the perforation step, the plurality of through holes are formed with regular spacing relative to the length and width directions of the adhesive layer.

15. The method for manufacturing a gas emission membrane according to claim 13, in, In the cutting step, the permeable layer and the adhesive layer are cut at regular intervals relative to the length and width directions of the adhesive layer.

16. A method for manufacturing a secondary battery box, comprising: The molding steps for forming a cup-shaped portion that houses the electrode assembly within an external material component; A perforation step in which an opening is formed in the outer material part having the cup-shaped portion; A lamination step for manufacturing a gas emission membrane by laminating a permeable layer onto an adhesive layer, the adhesive layer being thermally bonded and having pores formed therein, the permeable layer having higher gas permeability than the adhesive layer and having the same thickness as or being thicker than the adhesive layer; and The attachment step of attaching the gas emission membrane to the external material to cover the opening.

17. The method for manufacturing a secondary battery box according to claim 16, in, The attachment step includes: The step of attaching the gas emission membrane to the external material by pressing the gas emission membrane and the external material with a high-temperature sealing device.

18. The method for manufacturing a secondary battery box according to claim 17, in, In the attachment step, the sealing device presses down on the entire area of ​​the gas emission membrane.

19. The method for manufacturing a secondary battery box according to claim 17, in, In the attachment step, the sealing device applies heat and pressure to both sides of the gas emission membrane and the external material component.

20. The method for manufacturing a secondary battery box according to claim 16, in, The perforation step includes: The step of forming the opening on the periphery of the cup-shaped portion formed in the outer material component.

21. The method for manufacturing a secondary battery box according to claim 16, in, The perforation step includes: The step of forming the opening on the peripheral surface of the cup-shaped portion formed in the outer material component.

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