Pouch, secondary battery including the same, and method of manufacturing the same

Abstract

This invention relates to a pouch cell, a secondary battery including the pouch cell, and a method for manufacturing the pouch cell. The method for manufacturing a secondary battery according to the invention includes: a venting step of forming vents in an aluminum sheet; a lamination step of laminating a polymer layer onto the aluminum sheet to manufacture the pouch cell; a housing step of housing an electrode assembly within the pouch cell; and a sealing step of sealing the outer peripheral surface of the pouch cell.

Description

Technical Field

[0001] Cross-reference to related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2020-0182658, filed on December 23, 2020, which is incorporated herein by reference in its entirety. Technical Field

[0004] This invention relates to a pouch cell, a secondary battery including the pouch cell, and a method for manufacturing the pouch cell. Background Technology

[0005] Unlike primary batteries, secondary batteries are rechargeable and offer greater potential for miniaturization and high capacity. Therefore, much research is currently being conducted on secondary batteries. With technological advancements and increasing demand for mobile devices, the need for secondary batteries as an energy source is also rapidly growing.

[0006] Rechargeable batteries are classified into coin-shaped batteries, cylindrical batteries, prismatic batteries, and pouch batteries based on the shape of their casings. In these secondary batteries, the electrode assembly installed in the casing is a rechargeable and discharging power generation device with a structure consisting of stacked electrodes and separators.

[0007] Electrode assemblies can be broadly categorized as follows: gel roll type electrode assemblies, where a diaphragm is inserted between the positive and negative electrodes, which are provided as sheets coated with active materials, and then the positive, diaphragm, and negative electrodes are wound together; stacked type electrode assemblies, in which multiple positive and multiple negative electrodes with diaphragms spaced apart are sequentially stacked; and stacked / folded type electrode assemblies, in which stacked unit cells are wound together with a separation membrane having a relatively long length.

[0008] In secondary batteries, gases are generated due to the decomposition of the internal electrolyte under the influence of temperature and potential changes during operation. Although the amount of gas is small under normal operating conditions, it is still a significant amount considering the battery's shelf life of over 10 years. Various studies have been conducted to remove the gases generated inside the battery, and methods for attaching devices for gas venting to the battery surface have been investigated. However, a problem exists: during the device attachment process, electrolyte leakage at the seal and moisture penetration through the seal cause battery performance degradation.

[0009] [Prior Art Documents] (Patent Documents) Korean Patent Publication No. 10-2014-0015647 Summary of the Invention

[0010] Technical issues

[0011] One aspect of the present invention is to provide a soft pack capable of venting internal gas, a secondary battery including the soft pack, and a method for manufacturing the soft pack.

[0012] Technical solution

[0013] A method for manufacturing a flexible package for accommodating electrode components according to an embodiment of the present invention includes: a hole forming step of forming vent holes in an aluminum sheet; and a lamination step of laminating a polymer layer on the aluminum sheet.

[0014] Additionally, a method for manufacturing a secondary battery according to an embodiment of the present invention includes: a hole forming step, forming vent holes in an aluminum sheet; a lamination step, laminating a polymer layer on the aluminum sheet to manufacture a pouch; an accommodating step, accommodating an electrode assembly in the pouch; and a sealing step, sealing the outer peripheral surface of the pouch.

[0015] Additionally, according to one embodiment of the present invention, a soft package is configured to house an electrode assembly, the soft package comprising: an aluminum sheet; and a polymer layer laminated thereto together with the aluminum sheet, wherein venting holes are formed in the aluminum sheet.

[0016] A secondary battery according to an embodiment of the present invention includes: an electrode assembly in which electrodes and a separator are alternately stacked to bond with each other; and a pouch configured to house the electrode assembly, wherein the pouch includes an aluminum sheet and a polymer layer laminated together with the aluminum sheet, and vent holes are formed in the aluminum sheet.

[0017] Beneficial effects

[0018] According to the present invention, vent holes can be formed on the flexible aluminum sheet, and a polymer can be laminated on the aluminum sheet, so that internal gas passes through the polymer layer through the vent holes and is then discharged to the outside. Attached Figure Description

[0019] Figure 1 This is a plan view illustrating the hole-forming process in a method for manufacturing pouch cells and secondary batteries according to an embodiment of the present invention.

[0020] Figure 2 This is a cross-sectional view illustrating the lamination process in a method for manufacturing pouch cells and secondary batteries according to an embodiment of the present invention.

[0021] Figure 3 This is a plan view showing the state of the electrode assembly before it is housed in a pouch during the housing step of a method for manufacturing a secondary battery according to an embodiment of the present invention.

[0022] Figure 4 This is a plan view showing the state in which the electrode assembly is housed in a pouch during the housing step of a method for manufacturing a secondary battery according to an embodiment of the present invention.

[0023] Figure 5 This is a plan view illustrating the sealing process in a method for manufacturing a secondary battery according to an embodiment of the present invention. Detailed Implementation

[0024] The objectives, specific advantages, and novel features of the present invention will become clearer from the following detailed description taken in conjunction with the accompanying drawings. It should be noted that throughout this specification, reference numerals are used as often as possible to represent components of the drawings, even if they are shown in other drawings. Furthermore, the invention may be embodied in different forms and should not be construed as being limited to the embodiments set forth herein. In the following description of the invention, detailed descriptions of related techniques that would unnecessarily obscure the essence of the invention will be omitted.

[0025] Methods for manufacturing flexible packaging

[0026] Figure 1 This is a plan view illustrating the hole-forming process in a method for manufacturing pouch cells and secondary batteries according to an embodiment of the present invention. Figure 2 This is a cross-sectional view illustrating the lamination process in a method for manufacturing pouch cells and secondary batteries according to an embodiment of the present invention.

[0027] Reference Figure 1 and Figure 2 According to an embodiment of the present invention, a method for manufacturing a pouch for a secondary battery is a method for manufacturing a pouch that houses an electrode assembly, and the method includes: a hole forming step of forming an vent hole 113a in an aluminum sheet 113; and a lamination step of laminating polymer layers 111 and 116 on the aluminum sheet 113 to manufacture a pouch 110.

[0028] For more details, see [link to relevant documentation]. Figure 1 In the hole forming process, vent holes 113a can be formed in the aluminum sheet 113.

[0029] In addition, during the hole forming process, when the electrode assembly is accommodated, the vent hole 113a can be formed to be disposed between the electrode assembly and the outer peripheral surface of the soft package 110.

[0030] In addition, during the hole forming process, an vent hole 113a can be formed in the portion of the aluminum sheet 113 on the side where the electrode lead connected to the electrode assembly is provided.

[0031] Furthermore, in the hole forming process, the vent hole 113a can be formed in a circular shape in the aluminum sheet 113. Here, in the hole forming process, the vent hole 113a can be formed in the aluminum sheet 113 with a size of 1 mm to 9 mm.

[0032] Reference Figure 2In the lamination process, the flexible package 110 can be manufactured by laminating polymer layers 111 and 116 onto aluminum sheet 113.

[0033] Polymer layers 111 and 116 may include a first polymer layer 116 and a second polymer layer 111. Here, in the lamination process, the first polymer layer 116 and the second polymer layer 111 may be formed on both surfaces of the aluminum sheet 113 to cover the vent holes 113a formed in the aluminum sheet 113. Here, each of the first polymer layer 116 and the second polymer layer 111 may contain a polymer material. Therefore, the first polymer layer 116 and the second polymer layer 111, which are permeable to gases such as CO and CO2 and respectively contain polymer materials, can cover the vent holes 113a, thereby allowing internal gases to escape and preventing electrolyte leakage from the vent holes 113a.

[0034] In the lamination process, the first polymer layer 116, the aluminum sheet 113, and the second polymer layer 111 can be laminated from the inside to the outside of the electrode assembly.

[0035] Here, in the lamination process, a first polymer layer 116, an aluminum sheet 113, and a second polymer layer 111 with thicknesses of 10 μm to 90 μm can be laminated.

[0036] In addition, during the lamination process, a nylon layer 112 can also be laminated between the aluminum sheet 113 and the second polymer layer 111.

[0037] The second polymer layer 111 can be made of polyethylene terephthalate (PET) material.

[0038] Alternatively, as an example, the first polymer layer 116 may be made of polypropylene (PP) material.

[0039] In another example, the inner layer 115 of the first polymer layer 116, which houses the electrode assembly, is made of polypropylene (PP) material, and the outer layer 114 facing the aluminum sheet 113 is made of polyphthalamide (PPA) material.

[0040] Methods for manufacturing secondary batteries

[0041] The following describes a method for manufacturing a secondary battery according to an embodiment of the present invention.

[0042] Figure 3 This is a plan view showing the state of the electrode assembly before it is housed in the pouch during the housing step of a method for manufacturing a secondary battery according to an embodiment of the present invention. Figure 4 This is a plan view showing the state in which the electrode assembly is housed in a pouch during the housing step of a method for manufacturing a secondary battery according to an embodiment of the present invention. Figure 5 This is a plan view illustrating the sealing process in a method for manufacturing a secondary battery according to an embodiment of the present invention.

[0043] Reference Figures 1 to 5 A method for manufacturing a secondary battery according to an embodiment of the present invention includes: a hole forming step, forming an vent hole 113a in an aluminum sheet 113 to manufacture a soft pack 110; a lamination step, laminating polymer layers 111 and 116 on the aluminum sheet 113; an accommodating step, accommodating an electrode assembly 120 in the soft pack 110; and a sealing step, sealing the outer peripheral surface of the soft pack 110 to manufacture a secondary battery 100.

[0044] A method for manufacturing a secondary battery according to an embodiment of the present invention relates to a method for manufacturing a secondary battery comprising a pouch cell manufactured by the method for manufacturing a pouch cell according to the foregoing embodiments. Therefore, the content of this embodiment that is repeated with the content of the foregoing embodiments will be omitted or briefly described, and the differences between them will be mainly described.

[0045] For more details, see [link to relevant documentation]. Figure 1 In the hole forming process, vent holes 113a can be formed in the aluminum sheet 113.

[0046] In addition, during the hole forming process, when the electrode assembly 120 is accommodated, the vent hole 113a can be formed to be disposed between the outer peripheral surface of the electrode assembly 120 and the soft package 110.

[0047] Furthermore, in the hole forming process, the vent hole 113a can be formed in the portion of the aluminum sheet 113 on the side where the electrode leads are provided. That is, the vent hole 113a can be provided between the sealing portion S formed on the outer peripheral surface of the aluminum sheet 113 in the subsequent sealing process and the electrode assembly 120 in the aluminum sheet 113, and in the plan view, the vent hole 113a can be formed in the direction where the electrode leads 130 are provided in one of the four directions of the secondary battery 100 (see...). Figure 3 and Figure 5 ).

[0048] Furthermore, in the hole forming process, the vent hole 113a can be formed in a circular shape in the aluminum sheet 113. Here, in the hole forming process, the vent hole 113a can be formed in the aluminum sheet 113 with a size of 1 mm to 9 mm.

[0049] Reference Figure 2 In the lamination process, the flexible package 110 can be manufactured by laminating polymer layers 111 and 116 on the aluminum sheet 113.

[0050] Polymer layers 111 and 116 may include a first polymer layer 116 and a second polymer layer 111. Here, in the lamination process, the first polymer layer 116 and the second polymer layer 111 may be formed on both surfaces of the aluminum sheet 113 to cover the vent holes 113a formed in the aluminum sheet 113. Here, each of the first polymer layer 116 and the second polymer layer 111 may contain a polymer material. Therefore, the first polymer layer 116 and the second polymer layer 111, which contain polymer materials and are permeable to gases such as CO and CO2, can cover the vent holes 113a, thereby venting internal gases and preventing electrolyte leakage from the vent holes 113a.

[0051] In the lamination process, the first polymer layer 116, the aluminum sheet 113, and the second polymer layer 111 can be laminated from the inside to the outside of the electrode assembly 120.

[0052] Here, in the lamination process, a first polymer layer 116, an aluminum sheet 113, and a second polymer layer 111 with thicknesses of 10 μm to 90 μm can be laminated.

[0053] In addition, during the lamination process, a nylon layer 112 can also be laminated between the aluminum sheet 113 and the second polymer layer 111.

[0054] The second polymer layer 111 can be made of polyethylene terephthalate (PET) material.

[0055] Alternatively, as an example, the first polymer layer 116 may be made of polypropylene (PP) material.

[0056] In another example, the inner layer 115 of the first polymer layer 116, which houses the electrode assembly 120, is made of polypropylene (PP) material, and the outer layer 114 facing the aluminum sheet 113 is made of polyphthalamide (PPA) material.

[0057] Reference Figure 3 and Figure 4 During the housing process, the electrode assembly 120 can be housed in the soft package 110. The electrode assembly 120 can be a rechargeable and dischargeable power generation element and has a shape in which electrodes and diaphragms are alternately stacked and assembled with each other.

[0058] Additionally, in the housing process, for example, the electrode assembly 120 may be disposed on one side of the soft package 110, and then covered with the other side to house the electrode assembly 120. As another example of the housing process, the electrode assembly 120 may be housed by forming a housing portion that houses the electrode assembly 120.

[0059] Additionally, during the housing process, electrode leads 130 for connecting the electrode assembly 120 to an external device may also be accommodated. Here, one side of the electrode lead 130 may be connected to the electrode of the electrode assembly 120 and housed in the soft case 110, while the other side of the electrode lead 130 may extend to the outside of the soft case 110 and then connect to the external device.

[0060] Reference Figure 5 During the sealing process, the outer peripheral surface of the soft package 110 can be sealed.

[0061] In addition, during the sealing process, the sealing part S can be formed by sealing the outer peripheral surface of the soft package 110 in three or four directions.

[0062] In addition, during the sealing process, heat can be applied to both sides of the outer peripheral surface of the soft package 110 to fuse the outer peripheral surface, thereby forming the sealing part S.

[0063] Soft pack

[0064] The following will describe a soft package according to an embodiment of the present invention.

[0065] Reference Figure 1 and Figure 2 According to one embodiment of the present invention, the flexible package 110 is a flexible package 110 that accommodates the electrode assembly 120. The flexible package 110 includes an aluminum sheet 113 and polymer layers 111 and 116 laminated together with the aluminum sheet 113. Venting holes 113a are formed in the aluminum sheet 113 (see...). Figure 3 ).

[0066] The flexible case 110 according to one embodiment of the present invention relates to a flexible case 110 manufactured by the method of manufacturing a flexible case according to the above embodiments. Therefore, the content of this embodiment that is repeated with the content of the foregoing embodiments will be omitted or briefly described, and the differences between them will be mainly described.

[0067] More specifically, the flexible package 110 can accommodate the electrode assembly 120. Here, the accommodating portion for accommodating the electrode assembly 120 can be formed in the flexible package 110.

[0068] At this point, the electrode assembly 120 housed in the soft package 110 is a rechargeable and dischargeable power generation element, and electrodes and a separator are alternately stacked to bond with each other. The electrode assembly 120 may also include electrode leads 130 connected to the ends of the electrodes. Here, the electrode assembly 120 can be connected via the electrode leads 130 (see...) Figure 3 Electrically connected to external devices.

[0069] Additionally, the flexible package 110 may include an aluminum sheet 113 and polymer layers 111 and 116 laminated together with the aluminum sheet 113.

[0070] Aluminum sheet 113 can be formed as a sheet made of aluminum material to form a layer.

[0071] Alternatively, an vent hole 113a can be formed in the aluminum sheet 113. In this case, the vent hole 113a can be formed in the aluminum sheet 113 with a size of 1 mm to 9 mm.

[0072] Additionally, refer to Figures 1 to 3 In the soft package 110, an exhaust port 113a may be formed between the electrode assembly 120 and the outer peripheral surface of the soft package 110.

[0073] Additionally, an exhaust port 113a may be formed in the portion of the aluminum sheet 113 on the side where the electrode lead 130 is provided.

[0074] Polymer layers 111 and 116 may include a first polymer layer 116 and a second polymer layer 111. Here, the first polymer layer 116 and the second polymer layer 111 may be formed on both surfaces of the aluminum sheet 113 to cover the vent hole 113a formed in the aluminum sheet 113. Here, each of the first polymer layer 116 and the second polymer layer 111 may contain a polymer material. Therefore, the first polymer layer 116 and the second polymer layer 111, each containing a polymer material, permeable to gases such as CO and CO2, can cover the vent hole 113a, thereby allowing internal gases to escape and preventing electrolyte leakage from the vent hole 113a.

[0075] The first polymer layer 116, the aluminum sheet 113, and the second polymer layer 111 can be stacked from the inside to the outside of the electrode assembly 120. Here, the first polymer layer 116, the aluminum sheet 113, and the second polymer layer 111, with thicknesses of 10 μm to 90 μm, can be stacked and bonded together. In addition, in the flexible package 110, a nylon layer 112 can be laminated between the aluminum sheet 113 and the second polymer layer 111.

[0076] The second polymer layer 111 can be made of polyethylene terephthalate (PET) material.

[0077] Alternatively, as an example, the first polymer layer 116 may be made of polypropylene (PP) material.

[0078] In another example, the inner layer 115 of the first polymer layer 116, which houses the electrode assembly 120, is made of polypropylene (PP) material, and the outer layer 114 facing the aluminum sheet 113 is made of polyphthalamide (PPA) material.

[0079] A sealing portion S can be formed on the outer peripheral surface of the soft package 110 to seal the interior of the soft package 110. In this case, the sealing portion S can be formed by thermally fusing the outer peripheral surface of the soft package 110 in three or four directions.

[0080] Secondary batteries

[0081] The following will describe a secondary battery according to an embodiment of the present invention.

[0082] Reference Figure 1 and Figure 5 A secondary battery 100 according to an embodiment of the present invention includes: an electrode assembly, wherein electrodes and a separator are alternately stacked and bonded to each other; and a pouch 110 housing the electrode assembly 120. The pouch 110 includes an aluminum sheet 113 and polymer layers 111 and 116 laminated together with the aluminum sheet 113. A vent 113a is formed in the aluminum sheet 113.

[0083] The secondary battery 100 according to one embodiment of the present invention relates to a secondary battery manufactured by the method of manufacturing a secondary battery according to the foregoing embodiments. Therefore, the content of this embodiment that is repeated with the content of the foregoing embodiments will be omitted or briefly described, and the differences between them will be mainly described.

[0084] More specifically, in a secondary battery 100 according to an embodiment of the present invention, the electrode assembly 120 may be a rechargeable and dischargeable power generation device and is assembled by alternatingly stacking electrodes and separators.

[0085] Here, the electrodes can include positive and negative electrodes. Therefore, the positive electrode, the diaphragm, and the negative electrode can be arranged alternately.

[0086] Additionally, the electrode assembly 120 may also include electrode leads 130 connected to the ends of the electrodes. Here, the electrode assembly 120 can be electrically connected to an external device via the electrode leads 130.

[0087] The flexible package 110 can accommodate the electrode assembly 120. Here, a receiving portion for accommodating the electrode assembly 120 can be formed in the flexible package 110.

[0088] Additionally, the flexible pack 110 may include an aluminum sheet 113 and polymer layers 111 and 116 laminated together with the aluminum sheet 113.

[0089] Aluminum sheet 113 can be formed in the form of a sheet made of aluminum material to form a layer.

[0090] Alternatively, an vent hole 113a can be formed in the aluminum sheet 113. In this case, the vent hole 113a can be formed in the aluminum sheet 113 with a size of 1 mm to 9 mm.

[0091] Additionally, an exhaust port 113a may be formed between the electrode assembly 120 and the outer peripheral surface of the soft package 110.

[0092] Additionally, an exhaust port 113a may be formed in the portion of the aluminum sheet 113 on the side where the electrode lead 130 is provided.

[0093] Polymer layers 111 and 116 may include a first polymer layer 116 and a second polymer layer 111. Here, the first polymer layer 116 and the second polymer layer 111 may be formed on both surfaces of the aluminum sheet 113 to cover the vent hole 113a formed in the aluminum sheet 113. Here, each of the first polymer layer 116 and the second polymer layer 111 may contain a polymer material. Therefore, the first polymer layer 116 and the second polymer layer 111, each containing a polymer material, permeable to gases such as CO and CO2, can cover the vent hole 113a, thereby allowing internal gases to escape and preventing electrolyte leakage from the vent hole 113a.

[0094] The first polymer layer 116, the aluminum sheet 113, and the second polymer layer 111 can be stacked from the inside to the outside of the electrode assembly 120. Here, the first polymer layer 116, the aluminum sheet 113, and the second polymer layer 111, each with a thickness of 10 μm to 90 μm, can be stacked and bonded together. Furthermore, in the flexible package 110, a nylon layer 112 can be laminated between the aluminum sheet 113 and the second polymer layer 111.

[0095] The second polymer layer 111 can be made of polyethylene terephthalate (PET) material.

[0096] Alternatively, as an example, the first polymer layer 116 may be made of polypropylene (PP) material.

[0097] In another example, in the first polymer layer 116, the inner layer 115 housing the electrode assembly 120 is made of polypropylene (PP) material, and the outer layer 114 facing the aluminum sheet 113 is made of polyphthalamide (PPA) material.

[0098] A sealing portion S can be formed on the outer peripheral surface of the soft package 110 to seal the interior of the soft package 110. In this case, the sealing portion S can be formed by thermally fusing the outer peripheral surface of the soft package 110 in three or four directions.

[0099] While the present invention has been specifically shown and described with reference to exemplary embodiments thereof, it should be understood that the scope of the invention is not limited thereto. Those skilled in the art will understand that various changes to form and detail may be made without departing from the spirit and scope of the invention.

[0100] Furthermore, the scope of protection of this invention will be defined by the appended claims.

[0101] [Figure Labels]

[0102] 100: Secondary battery

[0103] 110: Soft Pack

[0104] 11 1: Second polymer layer

[0105] 112: Nylon layer

[0106] 113: Aluminum sheet (113)

[0107] 113a: Exhaust port

[0108] 116: First polymer layer

[0109] 120: Electrode assembly

[0110] 130: Electrode lead

[0111] S: Sealing part

Claims

1. A method of manufacturing a flexible package, the flexible package housing an electrode assembly, the method comprising: The hole-forming process creates vent holes in the aluminum sheet; as well as In the lamination process, a polymer layer is laminated onto the aluminum sheet. The polymer layer includes a first polymer layer and a second polymer layer. In the lamination process, the first polymer layer and the second polymer layer are laminated onto the two surfaces of the aluminum sheet, respectively. Both the first polymer layer and the second polymer layer cover the vent holes formed in the aluminum sheet.

2. The method according to claim 1, wherein, In the lamination process, the first polymer layer, the aluminum sheet, and the second polymer layer are laminated from the inside to the outside of the electrode assembly.

3. A method for manufacturing a secondary battery, the method comprising: The hole-forming process creates vent holes in the aluminum sheet; The lamination process involves laminating a polymer layer onto the aluminum sheet to manufacture a flexible package; The housing process involves housing the electrode assembly within the flexible package; as well as The sealing process involves sealing the outer periphery of the flexible package. The polymer layer includes a first polymer layer and a second polymer layer. In the lamination process, the first polymer layer and the second polymer layer are laminated onto the two surfaces of the aluminum sheet, respectively. Both the first polymer layer and the second polymer layer cover the vent holes formed in the aluminum sheet.

4. The method according to claim 3, wherein, In the lamination process, the first polymer layer, the aluminum sheet, and the second polymer layer are laminated from the inside to the outside of the electrode assembly.

5. The method according to claim 4, wherein, The first polymer layer is made of polypropylene (PP) material, and The second polymer layer is made of polyethylene terephthalate (PET) material.

6. The method according to claim 4, wherein, In the first polymer layer, the inner layer housing the electrode assembly is made of polypropylene (PP), and the outer layer facing the aluminum sheet is made of polyphthalamide (PPA). The second polymer layer is made of polyethylene terephthalate (PET) material.

7. The method according to claim 4, wherein, In the lamination process, a nylon layer is further laminated between the aluminum sheet and the second polymer layer before lamination.

8. The method according to claim 3, wherein, In the hole forming process, the vent hole is positioned between the electrode assembly and the outer peripheral surface of the flexible package when the electrode assembly is accommodated.

9. The method according to claim 8, wherein, In the receiving process, electrode leads configured to connect the electrode assembly to an external device are further received, and In the hole forming process, the vent hole is formed in the portion of the aluminum sheet on the side where the electrode lead is provided.

10. A soft package configured to house an electrode assembly, the soft package comprising: Aluminum sheet; as well as The polymer layer is laminated together with the aluminum sheet. Vent holes are formed in the aluminum sheet. The polymer layer comprises a first polymer layer and a second polymer layer, and the first polymer layer and the second polymer layer are respectively laminated on two surfaces of the aluminum sheet. Both the first polymer layer and the second polymer layer cover the vent holes formed in the aluminum sheet.

11. The flexible case according to claim 10, wherein, In the soft package, the first polymer layer, the aluminum sheet, and the second polymer layer are stacked from the inside to the outside of the electrode assembly.

12. A secondary battery, comprising: Electrode assemblies are composed of alternating layers of electrodes and diaphragms combined with each other. as well as A soft package is configured to house the electrode assembly. The flexible package includes an aluminum sheet and a polymer layer laminated together with the aluminum sheet, and Vent holes are formed in the aluminum sheet. The polymer layer comprises a first polymer layer and a second polymer layer, and the first polymer layer and the second polymer layer are respectively laminated on two surfaces of the aluminum sheet. Both the first polymer layer and the second polymer layer cover the vent holes formed in the aluminum sheet.

13. The secondary battery according to claim 12, wherein, In the soft package, the first polymer layer, the aluminum sheet, and the second polymer layer are stacked from the inside to the outside of the electrode assembly.

14. The secondary battery according to claim 13, wherein, The first polymer layer is made of polypropylene (PP) material, and The second polymer layer is made of polyethylene terephthalate (PET) material.

15. The secondary battery according to claim 13, wherein, In the first polymer layer, the inner layer housing the electrode assembly is made of polypropylene (PP), and the outer layer facing the aluminum sheet is made of polyphthalamide (PPA). The second polymer layer is made of polyethylene terephthalate (PET) material.

16. The secondary battery according to claim 13, wherein, In the flexible package, a nylon layer is further laminated between the aluminum sheet and the second polymer layer.

17. The secondary battery according to claim 12, wherein, The vent is formed in the soft package between the electrode assembly and the outer peripheral surface of the soft package.

18. The secondary battery of claim 17, further comprising electrode leads configured to connect the electrode assembly to an external device. in, The vent is formed in the portion of the aluminum sheet on the side where the electrode leads are located.

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