Pouch-type secondary battery

Abstract

The present invention relates to a pouch-type secondary battery, and more particularly, to a pouch-type secondary battery in which it is possible to easily recognize whether an electrolyte is depleted from the outside without disassembling a battery case.

Description

Technical Field

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Korean Patent Application No. 10-2024-0180376, filed with the Korean Intellectual Property Office on December 6, 2024, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0004] This disclosure relates to a pouch-type secondary battery, and more specifically, to a pouch-type secondary battery from which it is easy to determine from the outside whether the electrolyte is depleted without disassembling the battery casing. Background Technology

[0005] Generally, there are various types of rechargeable batteries, such as nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, lithium-ion polymer batteries, and lithium metal batteries. These rechargeable batteries are widely used not only in small products such as smartphones, smartwatches, smart rings, smart glasses, portable gaming devices, and electric bicycles, but also in large products requiring high power, such as electric or hybrid vehicles, in energy storage systems (ESS) for storing surplus generated electricity or renewable energy, and in backup power storage devices.

[0006] Such secondary batteries are classified into pouch-type and can-type based on the material of their casing. Pouch-type batteries house the electrode assembly in an irregularly shaped pouch made of a flexible polymer material. Can-type batteries, on the other hand, house the electrode assembly in a fixed-shape casing made of a material such as metal.

[0007] The pouch-type battery casing is manufactured by drawing and molding a flexible pouch film to form a cup. Furthermore, the pouch-type secondary battery is manufactured by accommodating the electrode assembly within the cup's receiving space, injecting electrolyte, and then folding the battery casing to seal the sealing portion.

[0008] As the lifespan of a secondary battery increases and it undergoes repeated charging and discharging, the amount of electrolyte inside decreases. When the electrolyte in a secondary battery is completely depleted, the battery should be discarded. However, without disassembling the battery casing, it is impossible to determine the remaining amount of electrolyte and whether it has been depleted. In particular, when electrolyte depletion is a critical factor in secondary battery experiments or research, there is a problem that disassembling the battery casing for each experiment to check for electrolyte depletion is very cumbersome and uneconomical. Summary of the Invention

[0009] Technical issues

[0010] The present disclosure aims to provide a pouch-type secondary battery that allows for easy external determination of electrolyte depletion without disassembling the battery casing.

[0011] The technical problems addressed in this disclosure are not limited to those described above, and other problems not mentioned herein may be clearly understood by those skilled in the art from the following description of this disclosure.

[0012] Technical solution

[0013] A pouch-type secondary battery for solving the above-mentioned problems according to embodiments of the present disclosure includes: an electrode assembly formed by stacking electrodes and a separator; a pouch-type battery housing housing the electrode assembly and an electrolyte therein; and a deformation unit whose shape deforms according to the remaining amount of electrolyte, wherein the deformation unit includes: a first deformation layer made of a flexible material and having waterproof and non-conductive properties; and a second deformation layer stacked on a first surface of the first deformation layer and changing volume upon absorbing electrolyte.

[0014] In addition, the first deformable layer and the second deformable layer can be attached to and fixed to each other.

[0015] In addition, the deformable unit can be formed in the shape of a disk.

[0016] In addition, the second deformable layer can expand in volume when absorbing electrolyte.

[0017] In addition, the first deformable layer can be configured such that when the volume of the second deformable layer expands, the second surface of the first deformable layer forms a flat surface, and when the volume of the second deformable layer contracts, the second surface of the first deformable layer forms a curved surface.

[0018] Additionally, the pouch-shaped battery casing can be configured such that: when the second surface of the first deformable layer forms a flat surface, the area where the deformable unit is placed protrudes outward in a flat shape, and when the second surface of the first deformable layer forms a curved surface, the area where the deformable unit is placed protrudes outward in a circular shape.

[0019] Additionally, the deformable unit can be positioned such that one of its surfaces is in direct contact with the pouch-shaped battery casing.

[0020] In addition, the deformation unit can be positioned such that the second surface of the first deformation layer is in direct contact with the pouch battery casing.

[0021] Additionally, the deformable unit can be placed between the outer wall of the cup portion that houses the electrode assembly in the pouch battery housing and the sealing portion of the pouch battery housing that is sealed.

[0022] Additionally, the electrode assembly may include: an electrode tab extending from the electrode; and an electrode lead connected to the electrode tab and exposed to the outside of the battery housing.

[0023] In addition, the surface orientation of the deformable unit can be toward the area where the electrode terminal block is connected to the electrode lead.

[0024] In addition, the surface direction of the second deformation layer in the deformation unit can be towards the area where the electrode terminal piece is connected to the electrode lead.

[0025] In addition, the deformation unit can cause the outer periphery of the second deformation layer to surround the outer periphery surface of the first deformation layer.

[0026] Other specific details of this disclosure are included in the detailed description and accompanying drawings.

[0027] Beneficial effects

[0028] According to embodiments of this disclosure, at least the following effects are achieved.

[0029] The remaining amount of electrolyte and whether it is depleted can be easily checked visually from the outside of the secondary battery without disassembling the pouch battery casing.

[0030] The effects of this disclosure are not limited to the examples above, and many more effects are included in this specification. Attached Figure Description

[0031] Figure 1 This is an assembly diagram of a pouch-type secondary battery 1 according to an embodiment of the present disclosure.

[0032] Figure 2 This is a perspective view showing the expanded state of the second deformable layer 152 of the deformable unit 15 according to an embodiment of the present disclosure.

[0033] Figure 3 yes Figure 2 Side view.

[0034] Figure 4 This is an enlarged cross-sectional view showing the deformation unit 15 of the second deformation layer 152 expanding in a pouch-type secondary battery 1 according to an embodiment of the present disclosure.

[0035] Figure 5 yes Figure 4 Enlarged plan view.

[0036] Figure 6 This is a perspective view showing the contracted state of the second deformable layer 152 of the deformable unit 15 according to an embodiment of the present disclosure.

[0037] Figure 7 yes Figure 6 Side view.

[0038] Figure 8 This is an enlarged cross-sectional view showing the deformable unit 15 of the second deformable layer 152 shrinking in a pouch-type secondary battery 1 according to an embodiment of the present disclosure.

[0039] Figure 9 yes Figure 8 Enlarged plan view.

[0040] Figure 10 This is a perspective view showing the expanded state of the second deformable layer 152a of the deformable unit 15a according to another embodiment of the present disclosure.

[0041] Figure 11 yes Figure 10 Side view.

[0042] Figure 12 This is a perspective view showing the contracted state of the second deformable layer 152a of the deformable unit 15a according to another embodiment of the present disclosure.

[0043] Figure 13 yes Figure 12 Side view. Detailed Implementation

[0044] The advantages and features of this disclosure, as well as the methods for implementing them, will become clear from the following detailed description of embodiments taken in conjunction with the accompanying drawings. However, this disclosure is not limited to the embodiments disclosed below, but can be implemented in various different forms, and these embodiments are provided only to complete the disclosure and fully inform those skilled in the art of its scope, which is limited only by the scope of the claims. Throughout this specification, the same reference numerals refer to the same parts.

[0045] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) are to be used in the sense that would be commonly understood by one of ordinary skill in the art to which this disclosure pertains. Furthermore, terms defined in common dictionaries should not be idealized or over-interpreted unless explicitly and specifically defined.

[0046] The terminology used in this specification is for the purpose of describing embodiments and is not intended to limit this disclosure. In this specification, the singular form also includes the plural form unless expressly stated otherwise in the phrase. The terms "comprising" and / or "including" as used in this specification do not exclude the presence or addition of one or more other components besides those mentioned.

[0047] In the following, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0048] Figure 1 This is an assembly diagram of a pouch-type secondary battery 1 according to an embodiment of the present disclosure.

[0049] According to this disclosure, it is easy to determine from the outside of the secondary battery 1 whether the electrolyte is depleted without disassembling the battery casing 13. To this end, the pouch-type secondary battery 1 according to this disclosure includes: an electrode assembly 10 formed by stacking electrodes and a separator; a pouch-type battery casing 13 containing the electrode assembly 10 and the electrolyte therein; and a deformable unit 15 whose shape deforms according to the remaining amount of electrolyte, wherein the deformable unit 15 includes: a first deformable layer 151 made of a flexible material and having waterproof and non-conductive properties; and a second deformable layer 152 stacked on a first surface of the first deformable layer 151 and changing volume upon absorbing electrolyte.

[0050] like Figure 1 As shown, the secondary battery 1 includes an electrode assembly 10 formed by alternately stacking electrodes and a separator, and a battery casing 13 that houses the electrode assembly 10 therein.

[0051] Electrode assembly 10 is formed by manufacturing electrodes (i.e., positive and negative electrodes) and stacking them on both sides of a separator to insulate them from each other. Electrode assembly 10 includes electrode tabs 11. Electrode tabs 11 extend from the electrodes of electrode assembly 10 and serve as a path for supplying power generated inside electrode assembly 10 to the outside. Electrode leads 12 are connected to electrode tabs 11 by spot welding or the like and are exposed to the outside of secondary battery 1. Moreover, secondary battery 1 supplies power to the outside through electrode leads 12. A portion of electrode leads 12 is surrounded by insulating units 14. Insulating units 14 are defined at a sealing portion 134 where the first housing 131 and the second housing 132 of battery housing 13 are thermally fused, thereby binding electrode leads 12 to battery housing 13.

[0052] The pouch-type battery casing 13 is made of a flexible material. When the flexible pouch film 135 is deep-drawn using a punch or the like, a portion of the flexible pouch film is stretched to form a cup portion 133 including a receiving space 1331 in the form of a recess, thereby manufacturing the battery casing 13.

[0053] When the electrode lead 12 is connected to the electrode tab 11 of the electrode assembly 10 and the insulating unit 14 is formed on a portion of the electrode lead 12, the electrode assembly 10 is housed in the receiving space 1331 of the cup portion 133, and electrolyte is injected into the receiving space. Then, the sealing portion 134 extending outward from the edges of the first housing 131 and the second housing 132 is sealed. At this time, the electrolyte is used to move lithium ions generated by the electrochemical reaction of the electrodes during the charging and discharging of the secondary battery 1, and may contain a non-aqueous organic electrolyte as a mixture of lithium salt and high-purity organic solvent, or a polymer electrolyte using a polymer. By this method, a pouch-type secondary battery 1 can be manufactured.

[0054] Figure 2 This is a perspective view showing the expanded state of the second deformable layer 152 of the deformable unit 15 according to an embodiment of the present disclosure, and Figure 3 yes Figure 2 Side view.

[0055] According to this disclosure, the pouch-type secondary battery 1 includes a deformable unit 15 whose shape is deformable according to the remaining amount of electrolyte in the pouch-type secondary battery. Moreover, the deformable unit 15 includes: a first deformable layer 151, which is made of a flexible material and has waterproof and non-conductive properties; and a second deformable layer 152, which is stacked on a first surface of the first deformable layer 151 and changes volume when absorbing electrolyte.

[0056] like Figure 2 and Figure 3 As shown, a first deformable layer 151 and a second deformable layer 152 are stacked on top of each other. The first deformable layer 151 is made of a flexible material and can have a thin film shape. Therefore, the shape of the first deformable layer 151 can be easily deformed as the volume of the second deformable layer 152 changes.

[0057] The first deformable layer 151 is formed to be in direct contact with the pouch-shaped battery casing 13. To prevent damage to the pouch-shaped battery casing 13, the first deformable layer 151 preferably does not absorb electrolyte, thus possessing waterproof properties. Additionally, the first deformable layer 151 can have non-conductive properties to prevent electrical grounding faults generated from the electrode assembly 10. For example, the first deformable layer 151 can be manufactured using a variety of materials without limitation, such as rubber or silicone resin, Teflon (PTFE), polyurethane (PU), thermoplastic polyurethane (TPU), ethylene propylene diene monomer (EPDM), polyethylene (PE), thermoplastic vulcanizate (TPV), polypropylene (PP), polyester, polystyrene (PS), polyvinyl chloride (PVC), and other synthetic resins that combine waterproof and non-conductive properties, as long as they are flexible and possess waterproof and non-conductive properties.

[0058] The second deformable layer 152 is formed by stacking on the first surface of the first deformable layer 151 and can have a thin film shape. Therefore, when the second deformable layer 152 is stacked on the first deformable layer 151 to form the deformable unit 15, the deformable unit 15 also has a thin film shape and can be easily placed inside the pouch-type battery housing 13 later.

[0059] The volume of the second deformable layer 152 varies depending on the remaining amount of electrolyte. Specifically, the volume of the second deformable layer 152 can expand when absorbing electrolyte and shrink when not absorbing electrolyte. For example, the second deformable layer 152 can be manufactured using materials such as cellulose, polyacrylamide gel, natural polymer gels (alginic acid, agarose), superabsorbent polymers (SAP) (sodium polyacrylate, polyvinyl alcohol (PVA)), bentonite, foaming polymers, etc. Particularly preferred are materials including reversible and reusable cellulose, polyacrylamide gel, and natural polymer gels. However, as long as the volume can vary depending on the remaining amount of electrolyte, the second deformable layer 152 can be manufactured without limitation using various materials.

[0060] The first deformable layer 151 and the second deformable layer 152 can be stacked on top of each other, and in particular, can be attached and fixed to each other. Therefore, the shape of the first deformable layer 151 can be deformed according to the change in volume of the second deformable layer 152. For this purpose, the first deformable layer 151 and the second deformable layer 152 can be bonded together by applying an adhesive, or they can be thermally fused together by applying heat and pressure. Furthermore, among the surfaces of the first deformable layer 151 and the second deformable layer 152 that contact each other, a protrusion can be formed on one surface and a groove can be formed on the other surface, such that the protrusion can be inserted into the groove to fix them together. That is, if the shape of the first deformable layer 151 can be deformed according to the change in volume of the second deformable layer 152, then the first deformable layer 151 and the second deformable layer 152 can be attached and fixed to each other in various ways without limitation.

[0061] The deformable unit 15 can have a wide plate shape, and particularly preferably a disk shape. If it has a rod shape that is only long in a certain direction, the first deformable layer 151 may deform concavely when the volume of the second deformable layer 152 expands. In that case, it may not be possible to visually inspect the deformed shape of the deformable unit 15 from the outside of the secondary battery 1.

[0062] Figure 4 This is an enlarged cross-sectional view showing the deformation unit 15 of the second deformation layer 152 expanding in a pouch-type secondary battery 1 according to an embodiment of the present disclosure, and Figure 5 yes Figure 4 Enlarged plan view.

[0063] According to this disclosure, the deformed shape of the deformable unit 15 should be easily inspected with the naked eye, even from the outside of the secondary battery 1. Therefore, as Figure 4 As shown, the deformable unit 15 is positioned such that one surface of it is in direct contact with the pouch-shaped battery casing 13, and specifically, the second surface of the first deformable layer 151 is positioned in direct contact with the pouch-shaped battery casing 13. Therefore, the remaining electrolyte level and whether the electrolyte is depleted can be easily inspected visually from the outside of the secondary battery 1 without disassembling the pouch-shaped battery casing 13. Here, the second surface of the first deformable layer 151 refers to the surface opposite to the first surface of the first deformable layer 151 on which the aforementioned second deformable layer 152 is stacked.

[0064] Due to the characteristics of the pouch-shaped battery casing 13 made of flexible material, the area where the deformable unit 15 is placed protrudes outward. However, if the deformable unit 15 is placed on the cup portion 133, the outward protrusion may spoil the appearance of the secondary battery 1, and may cause interference in the arrangement of the secondary battery 1 when the battery module or battery pack is subsequently manufactured by arranging the secondary battery 1.

[0065] Meanwhile, the sealing portion 134 is the area where the pouch-type battery casing 13 is sealed by applying heat and pressure while the sealing tool is in contact with both surfaces. Therefore, if the deformable unit 15 is placed on the sealing portion 134, it may be damaged by the heat and pressure of the sealing tool.

[0066] Therefore, as Figure 4 As shown, the deformable unit 15 can be placed between the outer wall of the cup portion 133 of the electrode assembly 10 in the pouch battery housing 13 and the sealing portion 134 of the pouch battery housing 13. Moreover, the surface direction of the deformable unit 15 can face the area where the electrode tab 11 and the electrode lead 12 are connected, and in particular, the surface direction of the second deformable layer 152 can face the area where the electrode tab 11 and the electrode lead 12 are connected.

[0067] The second deformable layer 152 expands in volume when absorbing electrolyte and contracts in volume when not absorbing electrolyte. If there is sufficient electrolyte inside the secondary battery 1, the second deformable layer 152 absorbs electrolyte, thereby expanding in volume. Then, as... Figure 4 As shown, the first deformable layer 151 stacked on the second deformable layer 152 can have its second surface flattened due to the expansion of the second deformable layer 152. At this time, the second surface of the first deformable layer 151 directly contacts the pouch-type battery casing 13, therefore, as... Figure 4 and Figure 5 As shown, the area of ​​the battery casing 13 where the deformable unit 15 is placed protrudes outward in a flat shape.

[0068] Figure 6This is a perspective view showing the contracted state of the second deformable layer 152 of the deformable unit 15 according to an embodiment of the present disclosure, and Figure 7 yes Figure 6 Side view.

[0069] If the electrolyte inside the secondary battery 1 is depleted, the second deformable layer 152 cannot absorb the electrolyte, thus shrinking in volume. Then, as... Figure 6 and Figure 7 As shown, the first deformable layer 151 stacked on the second deformable layer 152 can make its second surface curved due to the shrinkage of the second deformable layer 152.

[0070] Figure 8 This is an enlarged cross-sectional view showing the deformable unit 15 of the second deformable layer 152 shrinking in a pouch-type secondary battery 1 according to an embodiment of the present disclosure, and Figure 9 yes Figure 8 Enlarged plan view.

[0071] The second surface of the first deformable layer 151 is in direct contact with the pouch-shaped battery casing 13. Therefore, if the second surface of the first deformable layer 151 forms a curved surface, the area in the battery casing 13 where the deformable unit 15 is placed protrudes outward in a circular shape, such as... Figure 8 and Figure 9 As shown.

[0072] In this way, it can be determined even from the outside of the secondary battery 1: if the area where the deformable unit 15 is placed protrudes outward in a flat shape, the electrolyte is sufficient, while if the area protrudes outward in a circular shape, the electrolyte is depleted. That is, the remaining amount of electrolyte and whether the electrolyte is depleted can be easily checked visually from the outside of the secondary battery 1 without disassembling the pouch-type battery casing 13.

[0073] Figure 10 This is a perspective view showing the expanded state of the second deformable layer 152a of the deformable unit 15a according to another embodiment of the present disclosure, and Figure 11 yes Figure 10 Side view.

[0074] According to one embodiment of this disclosure, the first deformable layer 151 and the second deformable layer 152 can be attached to and fixed to each other. In this case, the diameters of the first deformable layer 151 and the second deformable layer 152 can be the same. However, according to another embodiment of this disclosure, the outer periphery of the second deformable layer 152a can have a shape surrounding the outer peripheral surface of the first deformable layer 151a.

[0075] like Figure 10 and Figure 11As shown, the outer periphery of the second deformable layer 152a protrudes with a constant width and thickness to form a specific space, and the first deformable layer 151a can be inserted into this specific space to manufacture the deformable unit 15a. In this case, the diameter of this specific space of the second deformable layer 152a can be the same as the diameter of the first deformable layer 151a. Therefore, without the need for an adhesive or thermal fusion process on the first deformable layer 151a and the second deformable layer 152a, the deformable unit 15a can be easily manufactured simply by inserting the first deformable layer 151a into the space of the second deformable layer 152a.

[0076] If the electrolyte inside the secondary battery 1 is sufficient, the second deformable layer 152a absorbs the electrolyte, thereby expanding in volume. Then, the first deformable layer 151a stacked on the second deformable layer 152a can flatten its second surface due to the expansion of the second deformable layer 152a. Moreover, the area in the battery casing 13 where the deformable unit 15a is placed protrudes outward in a flat shape.

[0077] Figure 12 This is a perspective view showing the contracted state of the second deformable layer 152a of the deformable unit 15a according to another embodiment of the present disclosure, and Figure 13 yes Figure 12 Side view.

[0078] If the electrolyte inside the secondary battery 1 is depleted, the second deformable layer 152a cannot absorb the electrolyte, thus shrinking in volume. Then, as... Figure 6 and Figure 7 As shown, the first deformable layer 151a stacked on the second deformable layer 152a can cause the second surface to become curved due to the contraction of the second deformable layer 152a. Furthermore, as... Figure 8 and Figure 9 As shown, the area in the battery casing 13a where the deformable unit 15a is placed protrudes outward in a circular shape.

[0079] In this way, it can be determined even from the outside of the secondary battery 1: if the area where the deformable unit 15a is placed protrudes outward in a flat shape, the electrolyte is sufficient, while if the area protrudes outward in a circular shape, the electrolyte is depleted. That is, the remaining amount of electrolyte and whether the electrolyte is depleted can be easily checked visually from the outside of the secondary battery 1 without disassembling the pouch-type battery casing 13.

[0080] Those skilled in the art to which this disclosure pertains will understand that this disclosure can be implemented in other specific forms without altering its technical concept or essential features. Therefore, it should be understood that the above embodiments are exemplary and not restrictive in all respects. The scope of this disclosure is defined by the appended claims described below, rather than the detailed description above, and various embodiments derived from the meaning and scope of the claims and their equivalents should be construed as including within the scope of this disclosure.

[0081] [Explanation of reference numerals in the attached figures]

[0082] 1: Secondary battery; 10: Electrode assembly

[0083] 11: Electrode connector 12: Electrode lead

[0084] 13: Battery casing 14: Insulation unit

[0085] 15: Deformation Unit 131: First Shell

[0086] 132: Second shell 133: Cup portion

[0087] 1331: Containment Space; 134: Sealed Section

[0088] 135: Bag film; 151: First deformable layer

[0089] 152: Second Deformation Layer

Claims

1. A pouch-type secondary battery, comprising: An electrode assembly formed by stacking electrodes and a diaphragm; A pouch-type battery housing that houses the electrode assembly and electrolyte; as well as A deformable unit, the shape of which deforms according to the remaining amount of electrolyte. The deformation unit includes: A first deformable layer, the first deformable layer being made of a flexible material and having waterproof and non-conductive properties; and A second deformable layer is stacked on the first surface of the first deformable layer and its volume changes when it absorbs the electrolyte.

2. The pouch-type secondary battery according to claim 1, in, The first deformable layer and the second deformable layer are attached to and fixed to each other.

3. The pouch-type secondary battery according to claim 1, in, The deformable unit is formed into a disk shape.

4. The pouch-type secondary battery according to claim 1, in, The second deformable layer expands in volume when it absorbs the electrolyte.

5. The pouch-type secondary battery according to claim 4, in, The first deformable layer is configured such that: When the volume of the second deformable layer expands, the second surface of the first deformable layer forms a flat surface, and when the volume of the second deformable layer contracts, the second surface of the first deformable layer forms a curved surface.

6. The pouch-type secondary battery according to claim 5, in, The pouch-type battery casing is configured such that: When the second surface of the first deformable layer forms a flat surface, the area where the deformable unit is placed protrudes outward in a flat shape, and When the second surface of the first deformable layer forms a curved surface, the area where the deformable unit is placed protrudes outward in a circular shape.

7. The pouch-type secondary battery according to claim 1, in, The deformable unit is positioned such that one surface of the deformable unit is in direct contact with the pouch-shaped battery casing.

8. The pouch-type secondary battery according to claim 7, in, The deformation unit is positioned such that the second surface of the first deformation layer is in direct contact with the pouch-shaped battery casing.

9. The pouch-type secondary battery according to claim 1, in, The deformable unit is placed between the outer wall of the cup portion that houses the electrode assembly in the pouch-shaped battery housing and the sealing portion of the pouch-shaped battery housing.

10. The pouch-type secondary battery according to claim 1, in, The electrode assembly includes: Electrode terminals extending from the electrode; and Electrode leads are connected to the electrode terminals and exposed to the outside of the battery housing.

11. The pouch-type secondary battery according to claim 10, in, The surface of the deformable unit faces the area where the electrode terminal block is connected to the electrode lead.

12. The pouch-type secondary battery according to claim 11, in, The surface of the second deformable layer in the deformable unit faces the area where the electrode terminal block is connected to the electrode lead.

13. The pouch-type secondary battery according to claim 1, in, The deformation unit causes the outer periphery of the second deformation layer to surround the outer periphery surface of the first deformation layer.

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