CN-122029677-A - Gas discharge film, secondary battery case, secondary battery, method for manufacturing gas discharge film, and method for manufacturing secondary battery case

Abstract

The present invention relates to a gas-discharge film which has excellent gas-discharge performance and can be efficiently manufactured. The gas discharge film according to the present invention covers an opening formed in a case of a secondary battery and discharges internal gas of the case, and includes 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 higher gas permeability than the adhesive layer, wherein the permeable layer may have the same thickness as the adhesive layer or may be formed thicker than the adhesive layer.

Inventors

• ZHU HUIYING
• HUANG ZHIYING
• PU ENSHU
• LI WEIZHEN
• JIN CHANGXUN
• YU HENGJUN

Assignees

• 株式会社LG新能源

Dates

Publication Date

20260512

Application Date

20241030

Priority Date

20231030

Claims (20)

1. 1. A gas discharge film that covers an opening formed in an exterior material member of a secondary battery and discharges internal gas of the exterior material member, the gas discharge film comprising: an adhesive layer having adhesiveness by 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 higher gas permeability than the adhesive layer, Wherein the permeable layer has the same thickness as the adhesive layer or is formed thicker than the adhesive layer.
2. 2. The gas discharge membrane according to claim 1, Wherein the permeable layer and the adhesive layer have a thickness of 10 μm to 100 μm.
3. 3. The gas discharge membrane according to claim 1, Wherein the adhesive layer is made of any one of polyethylene, polypropylene and polypropylene grafted maleic anhydride, and The permeable layer is made of polytetrafluoroethylene material.
4. 4. A secondary battery case, comprising: An exterior material member configured to accommodate an electrode assembly therein and having an opening formed therein, and A gas discharge film that covers the opening formed in the exterior material piece and discharges an internal gas of the exterior material piece, Wherein the gas discharge membrane comprises: an adhesive layer having adhesiveness by heat and having a through-hole formed in the adhesive layer, and A permeable layer laminated to one surface of the adhesive layer and having a higher gas permeability than the adhesive layer, Wherein the permeable layer has the same thickness as the adhesive layer or is formed thicker than the adhesive layer.
5. 5. The secondary battery case according to claim 4, Wherein the through hole and the opening overlap each other, and a diameter of the through hole is larger than a diameter of the opening.
6. 6. The secondary battery case according to claim 4, Wherein the center of the through hole and the center of the opening coincide with each other.
7. 7. The secondary battery case according to claim 6, Wherein the diameter of the opening is 1mm to 7mm.
8. 8. The secondary battery case according to claim 4, Wherein the adhesive layer of the gas discharge film is attached to an inner surface or an outer surface of the exterior material member.
9. 9. The secondary battery case according to claim 5, Wherein the exterior material member is composed of a laminated sheet including a resin layer, and The adhesive layer of the gas discharge film is made of any one of polyethylene, polypropylene grafted maleic anhydride, and is thermally fused to the resin layer of the laminated sheet.
10. 10. A secondary battery, comprising: An electrode assembly; an exterior material member accommodating the electrode assembly and having an opening formed therein, and A gas discharge film that covers the opening formed in the exterior material piece and discharges an internal gas of the exterior material piece, Wherein the gas discharge membrane comprises: an adhesive layer having adhesiveness by heat and having a through-hole formed in the adhesive layer, and A permeable layer laminated to one surface of the adhesive layer and having a higher gas permeability than the adhesive layer, Wherein the permeable layer has the same thickness as the adhesive layer or is formed thicker than the adhesive layer.
11. 11. The secondary battery according to claim 10, Wherein the exterior material piece includes: A cup-shaped portion configured to accommodate the electrode assembly; a sealing portion that forms an outermost portion of the exterior material and seals an interior of the exterior material, and A land portion forming a periphery of the cup portion and disposed between the cup portion and the seal portion, Wherein the opening is formed in the platform portion.
12. 12. The secondary battery according to claim 10, Wherein the exterior material member includes a cup-shaped portion configured to accommodate the electrode assembly, and The opening is formed on a peripheral surface of the cup-shaped portion.
13. 13. A method for manufacturing a gas-discharge membrane, comprising: a perforating step of forming a plurality of through holes in the adhesive layer having adhesiveness by heat; A lamination step of laminating the adhesive layer to a permeable layer having higher gas permeability than the adhesive layer and having the same thickness as the adhesive layer or formed thicker than the adhesive layer, and And a cutting step of cutting the permeable layer and the adhesive layer into unit films having a preset size, wherein each unit film has the through hole.
14. 14. The method for manufacturing a gas-discharge film according to claim 13, Wherein, in the perforating step, the plurality of through holes are formed to have regular intervals with respect to the length direction and the width direction of the adhesive layer.
15. 15. The method for manufacturing a gas-discharge film according to claim 13, Wherein in the cutting step, the permeable layer and the adhesive layer are cut at regular intervals with respect to the length direction and the width direction of the adhesive layer.
16. 16. A method for manufacturing a secondary battery case, comprising: a molding step of molding a cup-shaped portion accommodating the electrode assembly in the exterior material member; a perforating step of forming an opening in the exterior material member in which the cup-shaped portion is formed; A lamination step of manufacturing a gas discharge film by laminating a permeable layer, which has adhesiveness by heat and has a through hole formed in the adhesive layer, to an adhesive layer, which has higher gas permeability than the adhesive layer and has the same thickness as the adhesive layer or is formed thicker than the adhesive layer, and And an attaching step of attaching the gas discharge film to the exterior material member so as to cover the opening.
17. 17. The method for manufacturing a secondary battery case according to claim 16, Wherein, the attaching step includes: And a step of attaching the gas discharge film to the exterior material member by pressing the gas discharge film and the exterior material member with a high-temperature sealing device.
18. 18. The method for manufacturing a secondary battery case according to claim 17, Wherein, in the attaching step, the sealing means presses the entire area of the gas discharge film.
19. 19. The method for manufacturing a secondary battery case according to claim 17, Wherein, in the attaching step, the sealing means applies heat and pressure to both sides of the gas discharge film and the exterior material member.
20. 20. The method for manufacturing a secondary battery case according to claim 16, Wherein the perforating step comprises: and a step of forming the opening on a peripheral edge of the cup-shaped portion formed in the exterior material member.

Description

Gas discharge film, secondary battery case, secondary battery, method for manufacturing gas discharge film, and method for manufacturing secondary battery case Technical Field Cross Reference to Related Applications The present application claims priority from korean patent application No. 10-2023-0146958, filed on 10 months 30 in 2023, and korean patent application No. 10-2024-0148831, filed on 28 in 2024, the disclosures of which are incorporated herein by reference. Technical Field The present disclosure relates to a gas discharge film for discharging an internal gas of a secondary battery, a secondary battery cartridge including such a gas discharge film, a secondary battery including such a secondary battery cartridge, and the like. Background Batteries storing electric energy can be generally classified into primary batteries and secondary batteries. Primary batteries are disposable and consumable batteries, while secondary batteries are rechargeable batteries made using materials in which the oxidation and reduction processes between the current and the substrate are repeatable. That is, when the reduction reaction is performed on the material by the current, the power supply is charged, and when the oxidation reaction is performed on the material, the power supply is discharged, and electric power is generated while such charging and discharging are repeatedly performed. Secondary batteries may be classified into cylindrical batteries, pouch-shaped batteries, prismatic batteries, and the like according to their shapes. Among them, the pouch-shaped battery may be manufactured in a form in which an electrode assembly, in which a positive electrode, a negative electrode, and a separator are stacked, is received inside a pouch, and the outer portion of the pouch is sealed. Meanwhile, the electrolyte may be contained inside the pouch of the pouch-shaped battery together with the electrode assembly. At this time, residual moisture of the electrolyte or moisture permeated from the outside may react with lithium salt inside the pouch of the pouch-shaped battery to generate Hydrogen Fluoride (HF), and gases such as carbon dioxide, carbon monoxide, ethylene, and methane may be generated due to decomposition of the electrolyte. In addition, depending on the material of the positive electrode included in the electrode assembly of the pouch-shaped battery, hydrogen and HF may be additionally generated during the charge and discharge process, which may cause overheating due to overcharge and internal short circuit. Thus, a large amount of gas may be generated inside the bag. The pressure inside the bag may increase due to such gas, and the increased pressure may cause an expansion phenomenon in which the bag expands or a degassing phenomenon in which a portion of the bag breaks. The pouch-shaped battery may include a structure capable of discharging gas inside the pouch to the outside to prevent a degassing phenomenon. As an example of a structure capable of discharging the gas inside the bag to the outside, there is a structure in which holes are formed in the bag and the gas is discharged through a gas discharge film. A problem with pouch-shaped batteries including conventional gas discharge films is that the adhesive material may block the holes during the manufacturing process, thereby reducing gas discharge performance. Further, the conventional gas discharge membrane is a semi-permeable membrane and is attached to the bag in a thermal fusion method, and there is a problem in that holes formed in the bag are blocked due to excessive fusion when the gas discharge membrane is attached. Disclosure of Invention Technical problem The present disclosure is directed to providing a gas discharge film that has excellent gas discharge performance and is capable of preventing excessive fusion when attached to a pouch, a secondary battery cartridge including such a gas discharge film, and a secondary battery including such a secondary battery cartridge. Technical proposal The gas discharge film according to the present disclosure covers an opening formed in an exterior material member of a secondary battery and discharges internal gas of the exterior material member, and may include an adhesive layer having adhesiveness by 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 to have higher gas permeability than the adhesive layer, wherein the permeable layer may have the same thickness as the adhesive layer or may be formed thicker than the adhesive layer. The permeable layer and the adhesive layer may have a thickness of 10 μm to 100 μm. The adhesive layer may be made of any one of PE, PP and PPA, and the permeable layer may be made of a PTFE material. The secondary battery case according to the present disclosure may include an exterior material member configured to receive an electrode assembly therein and to ha