Secondary battery and electronic device

Abstract

The application discloses a secondary battery pole electronic device, which comprises a packaging bag and a roll core accommodated in the packaging bag. In a first direction, the length of the roll core is L mm, and in a second direction, the width of the roll core is W1 mm, 2≤L / W1≤6. The secondary battery further comprises an adhesive member, which is sleeved on the outer surface of the roll core in the winding direction of the roll core and is bonded between the roll core and the packaging bag. The first direction is the winding axis direction of the roll core, the second direction is the width direction of the roll core, and the first direction is perpendicular to the second direction. The adhesive member can tighten the pole pieces and the isolation film of each layer of the roll core, so that the pole pieces and the isolation film of each layer of the roll core are stably bonded and the gas production of the roll core is reduced, the expansion of the roll core is effectively alleviated, and the packaging bag is less likely to be burst. Meanwhile, the adhesive member can disperse the stress of the roll core, reduce the local stress impact, and further alleviate the expansion of the roll core. In addition, the adhesive member bonds the roll core and the packaging bag, reduces the impact of the roll core on the packaging bag, and further reduces the possibility of the packaging bag being burst.

Description

[Technical Field]

[0001] This application relates to the field of electrochemical technology, and more particularly to a secondary battery and electronic device. [Background Technology]

[0002] As people's demand for electronic products increases, rechargeable batteries are also required to fit into the different spaces of various electronic products. For example, for slim electronic products such as smart glasses and headphones, narrow and elongated rechargeable batteries are needed.

[0003] Due to their light weight and high energy density, pouch batteries are increasingly used in the aforementioned slender electronic products. Pouch batteries typically consist of a packaging bag and a core housed within the bag. In high-temperature environments or during long-term charge-discharge cycles, the core can expand. For narrow, elongated batteries, this expansion can cause the packaging bag to bulge, potentially even breaking the seal and leading to battery damage and leakage. [Summary of the Invention]

[0004] The embodiments of this application aim to provide a secondary battery and electronic device to reduce secondary battery swelling and lower the risk of secondary battery leakage.

[0005] In order to solve its technical problems, the embodiments of this application adopt the following technical solutions:

[0006] In a first aspect, this application proposes a secondary battery, including a packaging bag and a core housed within the packaging bag. The core has a length of L mm along a first direction and a width of W1 mm ​​along a second direction, where 2 ≤ L / W1 ≤ 6. The secondary battery also includes an adhesive component, which is fitted onto the outer surface of the core along its winding direction and adhered between the core and the packaging bag. The first direction is the winding axis direction of the core, and the second direction is the width direction of the core; the first direction is perpendicular to the second direction.

[0007] In the above technical solution, the adhesive component surrounds the core and is fitted onto its outer surface. This tightens the electrode layers and separator of the core, ensuring a stable bond between the core layers and reducing gas generation. This effectively alleviates core expansion and reduces the risk of the packaging bag being punctured. Simultaneously, the adhesive component disperses stress on the core, reducing localized stress impacts, further minimizing core expansion and packaging bag punctures. Furthermore, the adhesive component bonds the core to the packaging bag, reducing core movement within the bag and thus minimizing impact on the bag. This further reduces the risk of the packaging bag being punctured and improves the high-temperature resistance of the secondary battery.

[0008] In some preferred embodiments, 50≤L≤200, 20≤W1≤100. Further, 50≤L≤150, 25≤W1≤100, the adhesive core structure in this embodiment is particularly suitable for narrow and long secondary batteries.

[0009] In some preferred embodiments, there are multiple adhesive components, each sleeved on the outer surface of the core, and the multiple adhesive components are spaced apart from each other along a first direction. The arrangement of multiple adhesive components can disperse the stress on the core, reduce local stress impact, alleviate core expansion, and reduce the risk of the packaging bag being torn open.

[0010] In some preferred embodiments, the core has a first outer surface arranged along the winding direction, and adhesive members are sleeved at both ends of the first outer surface along the first direction. The two ends of the first outer surface are the edges of the core, and the bonding strength between the electrode sheet and the separator near these ends is relatively weak. Sleeving adhesive members at both ends of the first outer surface can further improve the bonding strength of the core and effectively disperse stress.

[0011] In some preferred embodiments, the number of adhesive components is N, where N ≥ X, and X = (L / W1) + 1. The number of adhesive components is limited according to the aspect ratio of the core, and N ≥ X, to ensure effective stress dispersion. The first outer surface of the core also has multiple uncovered areas, the number of which is M, where M = N - 1. The covered areas with adhesive components and the uncovered areas without adhesive components form a reinforcing structure similar to reinforcing ribs, which can further improve the bonding strength of the core and effectively disperse stress.

[0012] In some preferred embodiments, the core has a first outer surface disposed along the winding direction, the area of ​​the first outer surface being S1 mm. 2 The coverage area of ​​a single adhesive component on the first outer surface is S2 mm. 2 With a coverage area of ​​10% ≤ S2 / S1 ≤ 20%, each adhesive component has sufficient bonding area to the first outer surface, reducing stress concentration, minimizing damage to the core during tightening, and ensuring stable installation of the adhesive components. The total coverage area of ​​all adhesive components on the first outer surface is S3 mm. 2 With an adhesion ratio of 40% ≤ S3 / S1 ≤ 80%, the damage to the core caused by the adhesive components during tightening can be reduced. Furthermore, since each adhesive component also bonds the packaging bag, the adhesive components can be less likely to tear when the core and the packaging bag have a relative movement tendency or when relative movement occurs, thereby enhancing the bonding strength between the core and the packaging bag.

[0013] In some preferred embodiments, along the first direction, the width of the adhesive component is W2 mm, where 2 ≤ W2 ≤ 20 mm. This sufficient width ensures adequate bonding area to reduce stress concentration in the winding core and minimize damage to the winding core caused by the adhesive component during tightening. Along the third direction, the thickness of the adhesive component is T1 μm, where 5 ≤ T1 ≤ 80 mm. This ensures the bonding strength of the adhesive component while minimizing the space it occupies, thus maintaining the energy density of the secondary battery. The third direction is perpendicular to the winding direction and also perpendicular to the first direction.

[0014] In some preferred embodiments, the adhesive comprises hot melt adhesive or pressure-sensitive adhesive. Hot melt adhesive can be thermally cured during the secondary battery formation stage. The liquid state of the hot melt adhesive is viscous and can firmly bond the core and packaging bag. After use, the hot melt adhesive cools and solidifies rapidly, ensuring the adhesive strength between the core and the packaging bag. Pressure-sensitive adhesive is characterized by its ability to bond under slight pressure without additional heating, solvents, or water. The core and packaging bag are bonded simply by lightly pressing the outer surface of the packaging bag against the core; this operation is simple and convenient, and ensures the adhesive strength between the core and the packaging bag.

[0015] Optionally, the adhesive component includes a substrate layer, and two opposing surfaces of the substrate layer are respectively provided with a first adhesive layer and a second adhesive layer. The first adhesive layer is bonded to the core, and the second adhesive layer is bonded to the packaging bag. The first adhesive layer includes pressure-sensitive adhesive, and the second adhesive layer includes hot melt adhesive or pressure-sensitive adhesive.

[0016] Secondly, this application also proposes an electronic device including a secondary battery as described in any of the embodiments of the first aspect above.

[0017] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. [Attached Image Description]

[0018] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0019] Figure 1 This is a schematic diagram of the structure of a secondary battery according to some embodiments of this application;

[0020] Figure 2 This is a schematic diagram of the explosion of a secondary battery according to some embodiments of this application;

[0021] Figure 3This is a schematic diagram of the structure of a secondary battery according to some embodiments of this application;

[0022] Figure 4 This is a schematic diagram of the winding structure of the core in some embodiments of this application;

[0023] Figure 5 This is a schematic diagram illustrating the installation of the core and adhesive components according to some embodiments of this application;

[0024] Figure 6 This is a schematic diagram of the structure of the adhesive component according to some embodiments of this application;

[0025] Figure 7 This is a schematic diagram of the structure of the core in some embodiments of this application;

[0026] Figure 8 This is a top view of a secondary battery according to some embodiments of this application.

[0027] Explanation of reference numerals in the attached figures:

[0028] 100. Secondary batteries;

[0029] 10. Packaging bag; 10a. First bag body; 10b. Second bag body; 11. Receiving cavity; 12. Cavity; 13. Top seal; 14. Side seal;

[0030] 20. Core; 20a. First end; 20b. Second end; 21. First electrode; 22. Second electrode; 23. Separating membrane; 24. First outer surface; 241. Uncovered area;

[0031] 30. Adhesive component; 31. Substrate layer; 32. First adhesive layer; 33. Second adhesive layer;

[0032] 40. Electrode; 41. First Electrode; 42. Second Electrode;

[0033] X, first direction; Y, second direction; Z, third direction; M, winding direction.

Detailed Implementation Methods

[0034] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0035] It should be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component, or there can be one or more intermediate components in between. When a component is described as "connected to" another component, it can be directly connected to the other component, or there can be one or more intermediate components in between.

[0036] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0037] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0038] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. Furthermore, the technical features involved in the different embodiments of this application described below may be combined with each other as long as they do not conflict with each other.

[0039] In the first aspect, embodiments of this application provide a secondary battery 100, please refer to... Figure 1 The secondary battery 100 includes a packaging bag 10, a core 20, and an adhesive component 30. The core 20 is housed inside the packaging bag 10, and the adhesive component 30 is fitted onto the outer surface of the core 20 and bonded between the core 20 and the packaging bag 10.

[0040] For the above-mentioned packaging bag 10, please refer to Figures 1 to 3 The packaging bag 10 encloses a receiving cavity 11, which can accommodate the aforementioned core 20 and electrolyte (not shown in the figure). The packaging bag 10 can be a multi-layer composite film packaging bag containing a metal layer. The aforementioned packaging bag 10 can be an aluminum-plastic film packaging bag including a PP (polypropylene) layer and an aluminum layer. For example, the packaging bag 10 includes a first bag body 10a and a second bag body 10b. The first bag body 10a and / or the second bag body 10b are punched with a cavity 12. The core 20 can be disposed in the cavity 12. Then, the edges of the first bag body 10a and the edges of the second bag body 10b are sealed by heat sealing so that the PP layer of the first bag body 10a and the PP layer of the second bag body 10b are bonded together, thereby forming a complete packaging bag 10. The aforementioned cavity 12 forms the receiving cavity 11, and the heat-sealed portion forms the top sealing edge 13 and the side sealing edge 14 of the packaging bag 10.

[0041] For the aforementioned core 20, please refer to... Figure 1 and Figure 4The core 20 is housed within the receiving cavity 11 of the packaging bag 10. The core 20 includes a first electrode 21, a second electrode 22, and a separator 23. The first electrode 21, the second electrode 22, and the separator 23 are stacked and wound to form the core 20. The separator 23 is disposed between the first electrode 21 and the second electrode 22 to separate them. The first electrode 21 and the second electrode 22 have opposite polarities; one is a cathode electrode, and the other is an anode electrode. The separator 23 can be bonded between the first electrode 21 and the second electrode 22, reducing the shrinkage of the separator 23 and thus reducing the risk of short circuits due to contact between the first electrode 21 and the second electrode 22. It also improves the overall bonding strength of the core 20, mitigating the expansion of the core 20.

[0042] Please refer to Figure 2 , Figure 3 and Figure 4 The winding core 20 is electrically connected to tabs 40, which include a first tab 41 and a second tab 42. The first tab 41 is electrically connected to the first electrode 21, and the second tab 42 is electrically connected to the second electrode 22. For example, please refer to further details. Figure 5 Along the first direction X, the core 20 includes a first end 20a and a second end 20b disposed opposite to each other. A first tab 41 and a second tab 42 both extend from the first end 20a of the core 20. After the core 20 is housed in the packaging bag 10, the first end 20a is close to the top seal 13 of the packaging bag 10. Both the first tab 41 and the second tab 42 extend from the top seal 13. The tabs 40, by connecting the anode and cathode of the core 20, can transfer the positive and negative charges of the core 20 to an external circuit, enabling the secondary battery 100 to perform charging and discharging operations. Here, the first direction X is the winding axis direction of the core 20, which can also be considered the width direction of the first electrode 21 and / or the second electrode 22, or the length direction of the core 20.

[0043] For the aforementioned adhesive part 30, please refer to... Figure 1 and Figure 4 Along the winding direction M of the core 20, the adhesive component 30 surrounds the core 20 and is fitted onto its outer surface. This tightens the electrode layers and the separator 23 of the core 20, ensuring a stable bond between the layers and reducing gas generation. This effectively alleviates the expansion of the core 20 and reduces the risk of the packaging bag 10 being torn open. Optionally, the adhesive component 30 is bonded to the outer surface of the core 20, further enhancing the bonding strength between the electrode layers and the separator 23. Preferably, the adhesive component 30 is bonded between the core 20 and the packaging bag 10, reducing the movement of the core 20 within the packaging bag 10 and minimizing the impact of the core 20 on the packaging bag 10.

[0044] In some embodiments, the adhesive 30 includes hot melt adhesive or pressure-sensitive adhesive. Hot melt adhesive requires heating during use and can be thermally cured during the formation stage of the secondary battery 100. The liquid state of the hot melt adhesive is viscous and can firmly bond the core 20 and the packaging bag 10. After use, the hot melt adhesive cools and solidifies rapidly, ensuring the adhesive strength between the core 20 and the packaging bag 10. Pressure-sensitive adhesive is characterized by its ability to bond under slight pressure without the need for additional heating, solvents, or water. For example, after the core 20 is housed in the packaging bag 10, bonding between the core 20 and the packaging bag 10 can be achieved by gently pressing the outer surface of the packaging bag 10 against the core 20. This simple and convenient operation ensures the adhesive strength between the core 20 and the packaging bag 10.

[0045] In some other embodiments, please refer to Figure 6 The adhesive component 30 includes a substrate layer 31, and a first adhesive layer 32 and a second adhesive layer 33 are respectively disposed on two opposing surfaces of the substrate layer 31.

[0046] The substrate layer 31 serves as a support structure for the first adhesive layer 32 and the second adhesive layer 33, and has high strength. The first substrate layer 31 can be made of materials such as polyethylene, polypropylene, polyester, polyvinyl chloride, or polyimide. The first adhesive layer 32 is bonded to the core 20. The first adhesive layer 32 includes pressure-sensitive adhesive. After the core 20 is prepared, the adhesive component 30 is fitted onto the outer surface of the core 20, with the first adhesive layer 32 facing the core 20. By applying pressure to the adhesive component 30 towards the core 20, the first adhesive layer 32 can be bonded to the core 20. The second adhesive layer 33 is bonded to the packaging bag 10. The second adhesive layer 33 includes hot melt adhesive or pressure-sensitive adhesive. When hot melt adhesive is used, the heat generated during the formation stage of the secondary battery 100 can bond the hot melt adhesive to the packaging bag 10. When pressure-sensitive adhesive is used, the core 20 can be placed inside the packaging bag 10 first, and the pressure-sensitive adhesive can be bonded to the packaging bag 10 by slightly pressing the packaging bag 10 from the outside.

[0047] Optionally, the adhesive component 30 includes an adhesive resin, a tackifying resin, and a curing agent.

[0048] Adhesive resins are a class of chemical substances commonly used in the preparation of adhesives. They possess adhesive and bonding properties and can be used to bond various materials. Adhesive resins include ethylene-vinyl acetate copolymer, polypropylene resin, modified polypropylene resin, acrylic-modified polyolefin resin, polyethylene-trifluorochloroethylene resin, ethylene-acetic acid-acrylic acid copolymer, ethylene-propylene copolymer, ethylene-propylene terpolymer rubber, ethylene-propylene-styrene-acrylonitrile copolymer, ethylene-propylene terpolymer, isobutylene-isoprene rubber, isoprene rubber, maleic anhydride-modified polyolefin resin, modified polyphenylene ether resin, modified polystyrene resin, styrene-methyl methacrylate resin, nitrile rubber, polybutadiene rubber, polybutadiene-acrylonitrile resin, and polypropylene-butadiene rubber. The resin is selected from one or more of the following: polybutadiene styrene resin, styrene-ethylene butadiene styrene copolymer, styrene-isoprene styrene block copolymer, styrene-butadiene styrene block copolymer, styrene-butadiene rubber, styrene-maleic anhydride copolymer, syndiotactic polystyrene, ethylene-acrylic acid copolymer, polychlorotrifluoroethylene resin, polyvinylidene fluoride resin, ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, polyvinyl fluoride resin, polystyrene-acrylonitrile resin, polyorganosiloxane resin, furfural-phenol resin, furfural-acetone resin, furfuryl alcohol resin, phenolic resin, epoxy resin, or unsaturated polyester resin.

[0049] Tackifying resins are a class of special adhesive resins that enhance adhesion properties. When added to the adhesive component 30, they improve the tack and adhesion of the component 30. Tackifying resins can improve the flowability, adhesion, and shear resistance of the adhesive component 30 to stabilize the bond between the core 20 and the packaging bag 10. Tackifying resins include one or more of rosin resins, terpene resins, petroleum resins, phenolic resins, or epoxy resins.

[0050] A curing agent is a chemical substance used to promote the curing or hardening of the adhesive component 30. The curing agent reacts chemically with the main components of the aforementioned adhesive resin and / or tackifying resin, thereby transforming the adhesive from a liquid or semi-solid state to a solid state, enhancing adhesion and durability. For example, when the adhesive component 30 uses a hot melt adhesive, adding a curing agent to the hot melt adhesive can make the hot melt adhesive cure and harden faster, improving bond strength. Curing agents include one or more of epoxidized m-phenylenediamine, 4,4-diaminodiphenylmethane epoxy resin, triglycidyl p-aminophenol, hexamethylene diisocyanate, or diphenylmethane diisocyanate. These chemicals can react chemically with the substrate molecules in the hot melt adhesive to form a cross-linked structure, thereby interweaving the molecules of the hot melt adhesive and increasing the bond strength and stability. Furthermore, adding a curing agent can also improve the flowability of the hot melt adhesive, making it easier to apply.

[0051] The molecular weight of the adhesive resin can be selected from 10,000 to 10,000,000, and the ratio of adhesive resin, tackifying resin and curing agent is (50%-90%): (10%-50%): (0.1%-5%).

[0052] In the embodiments of this application, the secondary battery 100 may be a narrow and elongated type of battery, for example, please refer to Figure 5 and Figure 7 Along the first direction X, the length of the core 20 is L mm (excluding the first tab 41 and the second tab 42 mentioned above), and along the second direction Y, the width of the core 20 is W1 mm, where 2 ≤ L / W1 ≤ 6, making it suitable for electronic products such as smartwatches, smart glasses, and Bluetooth headsets. The second direction Y is the width direction of the core 20, and it is perpendicular to the first direction X. By using the adhesive 30 to attach and bond the secondary battery 100, the electrodes of the core 20 and the separator 23 can be firmly bonded, and gas generation in the core 20 can be reduced. This alleviates the expansion of the core 20, thereby reducing the risk of the packaging bag 10 being punctured. This is particularly suitable for narrow and long secondary batteries 100, for example, 50 ≤ L ≤ 200, 20 ≤ W1 ≤ 100; preferably, 50 ≤ L ≤ 150, 25 ≤ W1 ≤ 100.

[0053] Please refer to Figure 1 and Figure 5 Multiple adhesive components 30 are provided, each sleeved on the outer surface of the core 20, and spaced apart from each other along the first direction X. The arrangement of multiple adhesive components 30 can disperse the stress on the core 20, for example, distributing the stress on both sides of the core 20's width direction to each adhesive component 30, reducing localized stress impact, alleviating core 20 expansion, and reducing the risk of the packaging bag 10 being torn open. Optionally, the multiple adhesive components 30 are evenly distributed along the first direction X on the outer surface of the core 20 to uniformly disperse the stress in the core 20.

[0054] In some embodiments, the number of adhesive components 30 is N, where N ≥ X, and X = (L / W1) + 1. For example, if L / W1 = 3, then N ≥ X = 4. That is, when the aspect ratio of the core 20 is 3, more than four adhesive components 30 can be used. For example, all four adhesive components 30 can be fitted onto the core 20, and the four adhesive components 30 can be arranged alternately along the first direction X. Alternatively, if L / W1 = 3.5, then X = 4.5. When N≥5, more than 5 adhesive components 30 can be used to bond the core 20 to ensure stable installation of the core 20. The number of adhesive components 30 is limited according to the aspect ratio of the core 20, and N≥X to ensure effective stress dispersion. The larger the aspect ratio of the core 20, the more adhesive components 30 are needed to disperse the stress in different parts of the adhesive components 30 and reduce stress concentration.

[0055] Please refer to Figure 4and Figure 7 In some embodiments, the core 20 has a first outer surface 24 disposed along the winding direction M, the area of ​​the first outer surface 24 being S1 mm. 2 The coverage area of ​​a single adhesive component 30 on the first outer surface 24 is S2mm. 2 With a bonding area of ​​10% ≤ S2 / S1 ≤ 20%, each adhesive component 30 has sufficient bonding area with the first outer surface 24, which can reduce stress concentration, reduce tightening damage to the core 20, and stably mount the adhesive components. The total coverage area of ​​all adhesive components 30 on the first outer surface 24 is S3mm. 2 With an adhesion ratio of 40% ≤ S3 / S1 ≤ 80%, the damage caused by the tightening of the core 20 by each adhesive component 30 can be reduced. Furthermore, each adhesive component 30 also adheres to the packaging bag 10. In the case of the above-mentioned adhesion area, when the core 20 and the packaging bag 10 have a tendency to move relative to each other or when relative movement occurs, the tearing of the adhesive component 30 can be reduced, thereby enhancing the bonding strength between the core 20 and the packaging bag 10.

[0056] Since the adhesive component 30 is fitted onto the first outer surface 24 of the core 20, and its perimeter is substantially the same as the perimeter of the first outer surface 24 in the winding direction M, the coverage area of ​​the adhesive component 30 on the first outer surface 24 is related to the width of the adhesive component 30 in the first direction X. In the embodiments of this application, the width of the adhesive component 30 along the first direction X is W2 mm, where 2 ≤ W2 ≤ 20, to reduce stress concentration and reduce damage to the core 20 during tightening. Optionally, please refer to... Figure 8 Along the third direction Z, the thickness of the adhesive component 30 is T1 μm, where 5 ≤ T1 ≤ 80, to ensure the bonding strength of the adhesive component 30 while reducing the space occupied by the adhesive component 30, thus ensuring the energy density of the secondary battery 100. The third direction Z is perpendicular to the first direction X and also perpendicular to the winding direction M of the core 20. Since the winding direction M is actually composed of countless combinations of directions, each winding direction M corresponds to one third direction Z, therefore the third direction Z also includes countless directions. Figure 8 Only one third direction Z is shown in the figure. The third direction Z can also be considered as the direction from the adhesive to the core 20.

[0057] Optional, please refer to Figure 5The first outer surface 24 of the core 20 has multiple uncovered areas 241, which refer to the areas on the outer surface of the core 20 that are not covered by the adhesive 30. The number of uncovered areas 241 is M, where M = N-1. In this case, adhesive 30 is applied to both the first end 20a and the second end 20b of the first outer surface 24. Since the first end 20a and the second end 20b are both edges of the core 20, the bonding strength between the electrode sheet and the release liner 23 near these ends is relatively weak. Applying adhesive 30 near both ends can further improve the bonding strength of the core 20 and effectively disperse stress.

[0058] In the embodiments of this application, the adhesive component 30 surrounds the core 20 and is fitted onto the outer surface of the core 20. This tightens the electrode layers and separator 23 of the core 20, ensuring a stable bond between the layers and reducing gas generation within the core 20. This effectively alleviates the expansion of the core 20, thereby reducing the risk of the packaging bag 10 being punctured. Simultaneously, the adhesive component 30 disperses the stress on the core 20, reducing localized stress impacts, further alleviating the expansion of the core 20 and reducing the risk of the packaging bag 10 being punctured. Furthermore, the adhesive bonding between the core 20 and the packaging bag 10 reduces the movement of the core 20 within the packaging bag 10, thereby reducing the impact of the core 20 on the packaging bag 10 and further reducing the risk of the packaging bag 10 being punctured, thus improving the high-temperature resistance of the secondary battery 100.

[0059] In the embodiments of this application, a lithium-ion battery is used as an example to perform high-temperature testing.

[0060] Preparation of lithium-ion batteries

[0061] Example 1

[0062] (1) Preparation of negative electrode sheet:

[0063] Using graphite as the negative electrode active material, graphite, styrene-butadiene rubber (SBR) as the binder, and sodium carboxymethyl cellulose (CMC) as the thickener were mixed in a weight ratio of 96:2:2. Deionized water was added as a solvent to prepare a slurry with a solid content of 70 wt%, and the mixture was stirred evenly. The slurry was uniformly coated onto one surface of a 10 μm thick copper foil and dried to obtain a negative electrode sheet with a single-sided negative electrode active layer. The above steps were repeated on the other surface of the copper foil to obtain a negative electrode sheet with a double-sided negative electrode active layer.

[0064] (2) Preparation of the positive electrode sheet:

[0065] Lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 97.5:1.0:1.5. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt%, and the mixture was stirred until homogeneous. The slurry was uniformly coated onto one surface of a 12 μm thick aluminum foil and dried to obtain a positive electrode sheet with a single-sided positive active layer. The above steps were repeated on the other surface of the aluminum foil to obtain a positive electrode sheet with a double-sided positive active layer.

[0066] (3) Preparation of electrolyte:

[0067] In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are first mixed in a mass ratio of EC:EMC:DEC = 30:50:20 to form a basic organic solvent. Then, lithium salt lithium hexafluorophosphate (LiPF6) is added to the basic organic solvent, dissolved, and mixed evenly to obtain an electrolyte with a LiPF6 mass concentration of 12.5%.

[0068] (4) Preparation of the separating membrane:

[0069] A porous polyethylene membrane is used as the substrate layer, and a ceramic layer containing alumina ceramic and PVDF binder is coated on one side of the substrate layer as a diaphragm, wherein the mass percentage of alumina ceramic in the ceramic layer is 95%.

[0070] (5) Preparation of adhesive parts:

[0071] Polypropylene resin (adhesive resin), epoxy resin (tackifying resin), and epoxidized m-phenylenediamine (curing agent) are mixed in a ratio of 70%:25%:5% to prepare adhesive parts for hot melt adhesive.

[0072] (6) Core preparation:

[0073] The positive electrode, separator, and negative electrode are stacked and wound together. Nickel and aluminum sheets with a specification of 12mm×1mm are selected as tabs. The aluminum tabs are welded to the positive electrode (the aluminum foil of the positive electrode), and the nickel tabs are welded to the negative electrode (the copper foil of the negative electrode) to form a core.

[0074] (7) Core Assembly: The adhesive components are fitted and bonded to the outer surface of the core, with the core fitted at both ends closest to its length. A perforated aluminum-plastic film is placed in the assembly fixture with the perforated surface facing upwards. The core is placed in the perforation and pressed firmly to allow the hot melt adhesive to initially bond with the aluminum-plastic film. Then, another perforated aluminum-plastic film is placed on top of the core with the perforated surface facing downwards. The two aluminum-plastic films are then heat-sealed around their perimeter using a hot-pressing method to obtain the assembled core. The core has a length L = 50mm, a width W1 = 25mm, L / W1 = 2, and 3 adhesive components. These 3 adhesive components are evenly spaced along the length of the core, and each adhesive component has a width of 10mm along its length.

[0075] (8) Liquid injection and encapsulation: Electrolyte is injected into the assembled core, and after vacuum encapsulation, standing, and hot pressing, the adhesive parts are stably bonded between the core and the packaging bag. After shaping and other processes, the lithium-ion battery is obtained.

[0076] Example 2

[0077] Unlike the example, the core length L = 100mm and width W1 = 25mm; L / W1 = 4.

[0078] Example 3

[0079] Unlike the example, the core length L = 150 mm and the width W1 = 25 mm; L / W1 = 6.

[0080] Example 4

[0081] Unlike the example, the core length L = 100mm and width W1 = 35mm; L / W1 = 2.87.

[0082] Example 5

[0083] Unlike the example, the core length L = 200mm and width W1 = 35mm; L / W1 = 5.71.

[0084] Example 6

[0085] Unlike the example, the core length L = 100mm and width W1 = 50mm; L / W1 = 2.

[0086] Example 7

[0087] Unlike the example, the core length L = 200mm and width W1 = 50mm; L / W1 = 4.

[0088] Example 8

[0089] Unlike the example, the core length L = 200mm and width W1 = 100mm; L / W1 = 2.

[0090] Comparative Example 1

[0091] Unlike the previous embodiment, no adhesive components were provided.

[0092] Comparative Example 2

[0093] Unlike the example, the core length L = 200mm and width W1 = 25mm; L / W1 = 8.

[0094] Comparative Example 3

[0095] Unlike the example, the core length L = 200mm and width W1 = 150mm; L / W1 = 1.33.

[0096] Test methods

[0097] 1) Let the lithium-ion battery stand for 5 minutes at 25°C.

[0098] 2) Convert the lithium-ion battery to 3.0V at 0.5C DC;

[0099] 3) Let it sit for another 5 minutes;

[0100] 4) Set the lithium-ion battery to 0.5C CC 4.5V, CV to 0.05C;

[0101] 5) After standing for 5 minutes, transfer the lithium-ion battery into the heating furnace, heat it to 100°C at 5°C / min and keep it at that temperature for 5 hours.

[0102] 7) Turn off the heating and allow it to cool naturally to room temperature. Check the lithium-ion battery for damage or leakage.

[0103] The test results are shown in Table 1 below.

[0104] Table 1

[0105]

[0106]

[0107] According to Table 1 above, and in conjunction with Examples 1 to 8 and Comparative Example 1, it can be seen that when adhesive components are applied to the outer surface of the core, the leakage and breakage of lithium-ion batteries can be effectively reduced. In Comparative Example 2, the aspect ratio L / W1 of the core is relatively large, requiring more adhesive components for bonding, increasing the manufacturing process and hindering the improvement of lithium-ion battery production efficiency. Furthermore, the large aspect ratio of the core weakens the bonding force between the layers, making the core more prone to expansion, which may lead to damage to the side seals of the packaging bag. In Comparative Example 3, the aspect ratio L / W1 of the core is relatively small, and stress concentration may also occur at the top of the core (in the direction of tab extension). While adhesive components can limit the expansion of the sides of the core (both sides in the width direction of the core), they cannot limit the expansion at the top, which may cause the top seal of the packaging bag to be punctured. In conjunction with Examples 1 to 8 and Comparative Examples 2 and 3, when 2 ≤ L / W1 ≤ 6, the leakage and breakage of the packaging bag can be effectively reduced. In addition, in conjunction with Examples 1 to 8, 50≤L≤200 and 20≤W1≤100 can be selected; preferably 50≤L≤150 and 25≤W1≤100. Within this range, leakage due to packaging bag breakage is significantly reduced.

[0108] In the embodiments of this application, a lithium-ion battery is used as an example, and it is subjected to high-temperature testing again.

[0109] Example 9

[0110] Unlike Example 1, the number of adhesive parts is 1.

[0111] Example 10

[0112] Unlike Example 1, the number of adhesive parts is 2.

[0113] Example 11

[0114] Unlike Example 1, the number of adhesive parts is 4.

[0115] Example 12

[0116] Unlike Example 1, the number of adhesive parts is 5.

[0117] Example 13

[0118] Unlike Example 1, no adhesive parts are fitted at either end of the core near the length direction.

[0119] Example 14

[0120] Unlike Example 1, the adhesive part width W2 = 5mm, the number of adhesive parts is 1, and the adhesive part is bonded to the middle position in the length direction of the core.

[0121] Example 15

[0122] Unlike Example 1, the width of the adhesive part W2 is 5mm, and the number of adhesive parts is 2.

[0123] Example 16

[0124] Unlike Example 1, the width of the adhesive component W2 is 5mm, and the number of adhesive components is 3.

[0125] Example 17

[0126] Unlike Example 1, the adhesive part width W2 = 5mm, the number of adhesive parts is 3, and no adhesive parts are fitted at either end of the core near the length direction.

[0127] Example 18

[0128] Unlike Example 1, the width of the adhesive component W2 is 5mm, and the number of adhesive components is 4.

[0129] Example 19

[0130] Unlike Example 1, the width of the adhesive part W2 is 5mm, and the number of adhesive parts is 5.

[0131] Example 20

[0132] Unlike Example 1, the width of the adhesive component W2 is 5mm, and the number of adhesive components is 6.

[0133] The test results are shown in Table 2 below.

[0134] Table 2

[0135]

[0136]

[0137] According to Table 2 above, and in conjunction with Examples 9, 18, and 1 above, it can be seen that when neither end of the core near its length is fitted with adhesive, slight damage and leakage will occur. This may be due to stress concentration at both ends of the core along its length, causing the release liner to shrink, leading to core expansion and gas generation, resulting in packaging bag damage and leakage. Therefore, in the embodiments of this application, it is preferable that adhesive is fitted at both ends of the core near its length, i.e., the number of uncovered areas M = N-1.

[0138] Examples 1, 11, 12, 16, and 18-20 all satisfy the condition N≥X, X=(L / W1)+1, indicating a significant effect in reducing breakage and leakage in these examples. In contrast, Examples 9, 10, 14, and 15 do not satisfy N≥X, X=(L / W1)+1, resulting in a weaker effect in reducing breakage and leakage. Therefore, in this application, N≥X, X=(L / W1)+1 is used, preferably N=X, which reduces the number of adhesive components, thereby reducing costs and increasing the energy density of the secondary battery.

[0139] In the embodiments of this application, a lithium-ion battery is used as an example to perform high-temperature testing.

[0140] Example 21

[0141] Unlike Example 1, the number of adhesive components is 1, and the adhesive component is bonded to the middle position in the length direction of the core.

[0142] Example 22

[0143] Unlike Example 1, the number of adhesive parts is 2.

[0144] Example 23

[0145] Unlike Example 1, the number of adhesive parts is 4.

[0146] Example 24

[0147] Unlike Example 1, the number of adhesive parts is 5.

[0148] Example 25

[0149] Unlike Example 1, the adhesive part width W2 = 5mm, the number of adhesive parts is 1, and the adhesive part is bonded to the middle position in the length direction of the core.

[0150] Example 26

[0151] Unlike Example 1, the width of the adhesive component W2 is 5mm, and the number of adhesive components is 3.

[0152] Example 27

[0153] Unlike Example 1, the width of the adhesive part W2 is 5mm, and the number of adhesive parts is 5.

[0154] Example 28

[0155] Unlike Example 1, the width of the adhesive component W2 is 5mm, and the number of adhesive components is 8.

[0156] Example 29

[0157] Unlike Example 1, the width of the adhesive part W2 is 5mm, and the number of adhesive parts is 10.

[0158] Example 30

[0159] Unlike Example 1, the width of the adhesive part W2 is 15mm, and the number of adhesive parts is 1.

[0160] Example 31

[0161] Unlike Example 1, the width of the adhesive part W2 is 15mm, and the number of adhesive parts is 2.

[0162] Example 32

[0163] Unlike Example 1, the width of the adhesive part W2 is 15mm, and the number of adhesive parts is 3.

[0164] Example 33

[0165] Unlike Example 1, the width of the adhesive component W2 is 2.5 mm, and the number of adhesive components is 10.

[0166] The test results are shown in Table 3 below.

[0167] Table 3

[0168] Example 1 50 10 3 20％ 60％ 0 / 10 Example 21 50 10 1 20％ 20％ 1 / 10 Example 22 50 10 2 20％ 40％ 0 / 10 Example 23 50 10 4 20％ 80％ 0 / 10 Example 24 50 10 5 20％ 100％ 2 / 10 Example 25 50 5 1 10％ 10％ 2 / 10 Example 26 50 5 3 10％ 30％ 0 / 10 Example 27 50 5 5 10％ 50％ 0 / 10 Example 28 50 5 8 10％ 80％ 0 / 10 Example 29 50 5 10 10％ 100％ 1 / 10 Example 30 50 15 1 30％ 30％ 2 / 10 Example 31 50 15 2 30％ 60％ 1 / 10 Example 32 50 15 3 30％ 90％ 1 / 10 Example 33 50 2.5 10 5％ 50％ 2 / 10

[0169] In Example 33, the width of a single adhesive component is small, resulting in insignificant stress dispersion when it is fitted onto the outer surface of the core. This may lead to cracks forming on the outer surface of the core and potentially cause localized expansion of the core, resulting in packaging bag breakage and leakage. In Examples 24 and 29, completely covering the outer surface of the core in the winding direction not only affects energy density but also makes it difficult for the electrolyte to wet the core, easily leading to cyclic lithium plating. Combining Examples 21-33 above, it can be seen that when 10% ≤ S2 / S1 ≤ 20% and 40% ≤ S3 / S1 ≤ 80%, packaging bag breakage and leakage can be effectively reduced.

[0170] Secondly, embodiments of this application also provide an electronic device including the secondary battery 100 described in any of the embodiments of the first aspect. The electronic device in the embodiments of this application is not particularly limited and can be any electronic device known in the prior art. For example, electronic devices include, but are not limited to, Bluetooth headsets, mobile phones, tablets, laptops, electric toys, or power tools.

[0171] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this application as described above, which are not provided in detail for the sake of brevity; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A secondary battery, comprising a packaging bag and a core housed within the packaging bag, characterized in that, Along the first direction, the core length is L mm, and along the second direction, the core width is W1 mm, where 2 ≤ L / W1 ≤ 6; The secondary battery further includes an adhesive component. Along the winding direction of the winding core, the adhesive component is fitted onto the outer surface of the winding core and bonded between the winding core and the packaging bag. Multiple adhesive components are spaced apart from each other along the first direction, and the number of adhesive components is N, where N ≥ X = (L / W1) + 1; Wherein, the first direction is the winding axis direction of the core, the second direction is the width direction of the core, and the first direction is perpendicular to the second direction.

2. The secondary battery according to claim 1, characterized in that, 50≤L≤200, 20≤W1≤100.

3. The secondary battery according to claim 2, characterized in that, 50≤L≤150, 25≤W1≤100.

4. The secondary battery according to claim 1, characterized in that, There are multiple adhesive components, and each of the multiple adhesive components is sleeved on the outer surface of the core.

5. The secondary battery according to claim 4, characterized in that, The core has a first outer surface disposed along the winding direction; Along the first direction, the adhesive component is fitted onto both ends of the first outer surface.

6. The secondary battery according to claim 5, characterized in that, The first outer surface also has multiple uncovered areas, the number of which is M, where M = N-1.

7. The secondary battery according to claim 4, characterized in that, The winding core has a first outer surface arranged along the winding direction, the area of ​​the first outer surface being S1mm. 2 ; The coverage area of ​​a single adhesive component on the first outer surface is S2mm. 2 10%≤S2 / S1≤20%; The total coverage area of ​​all the adhesive components on the first outer surface is S3mm. 2 , 40%≤S3 / S1≤80%.

8. The secondary battery according to claim 1, characterized in that, Along the first direction, the width of the adhesive part is W2mm, where 2≤W2≤20; Along a third direction, the thickness of the adhesive part is T1μm, 5≤T1≤80, the third direction is perpendicular to the winding direction, and the third direction is perpendicular to the first direction.

9. The secondary battery according to claim 1, characterized in that, The adhesive components include hot melt adhesives or pressure-sensitive adhesives; or... The adhesive component includes a substrate layer, and two opposing surfaces of the substrate layer are respectively provided with a first adhesive layer and a second adhesive layer. The first adhesive layer is bonded to the core, and the second adhesive layer is bonded to the packaging bag. The first adhesive layer includes pressure-sensitive adhesive, and the second adhesive layer includes hot melt adhesive or pressure-sensitive adhesive.

10. An electronic device, characterized in that, Includes the secondary battery as described in any one of claims 1 to 9.

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