Adhesive tape for battery cell, battery cell and secondary battery

Abstract

The utility model provides an adhesive tape for a battery cell, the battery cell and a secondary battery, the adhesive tape comprises a base layer and an adhesive layer which are laminated, the base layer comprises casting polypropylene, and the adhesive layer comprises polyolefin adhesive. The adhesive tape for the battery cell, the battery cell and the secondary battery provided by the utility model are simple in structure and convenient to manufacture, the battery cell can be effectively packaged for a long time after heat sealing, and the problem of liquid leakage is avoided.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a tape for battery cells, a battery cell, and a secondary battery. Background Technology

[0002] With the continuous development of the new energy industry, higher requirements are being placed on battery cells. After the electrode components of the battery cell are side- and top-encapsulated with aluminum-plastic film, they undergo an electrolyte injection process. During electrolyte injection, the electrolyte may impact the adhesive tape inside the battery cell. Furthermore, the adhesive tape's adhesion decreases after being soaked in the electrolyte, and it may float to the final sealing position due to buoyancy. Thus, during final sealing of the battery cell, the adhesive tape, or some material from the tape, may remain between the aluminum-plastic film, resulting in insufficient final seal strength and causing leakage. Therefore, there is an urgent need for an adhesive tape with better encapsulation performance. Utility Model Content

[0003] In view of this, the purpose of this application is to provide a cell tape, a cell, and a secondary battery to solve the related problems mentioned in the background art.

[0004] In a first aspect, this application provides a tape for battery cells, the tape comprising a base layer and an adhesive layer stacked together, the base layer comprising cast polypropylene and the adhesive layer comprising polyolefin adhesive.

[0005] Furthermore, the thickness of the base layer is greater than the thickness of the adhesive layer.

[0006] Furthermore, the thickness of the base layer is 10 μm to 70 μm, and the thickness of the adhesive layer is 0.5 μm to 30 μm.

[0007] Furthermore, the thickness of the base layer is 30 μm, and the thickness of the adhesive layer is 15 μm.

[0008] Furthermore, the surface of the tape is provided with at least one wetting hole, the diameter of which is 0.1 mm to 2 mm.

[0009] Furthermore, a marking pattern is provided on the side of the base layer away from the adhesive layer, and the marking pattern has a length of 4mm to 10mm and a width of 4mm to 10mm.

[0010] Furthermore, the polyolefin adhesive includes polypropylene adhesive, polyethylene adhesive, and / or polybutene adhesive.

[0011] Furthermore, the melting point of the base layer is 125°C to 175°C, and the melting point of the adhesive layer is 50°C to 160°C.

[0012] A second aspect of this application provides a battery cell including at least one electrode assembly, the surface of which is adhered with the tape described in the first aspect above.

[0013] A third aspect of this application provides a secondary battery, including the cell described in the second aspect above.

[0014] As can be seen from the above, the battery cell tape, battery cell, and secondary battery provided in this application include a tape comprising a layered base layer and an adhesive layer. The base layer comprises cast polypropylene, and the adhesive layer comprises polyolefin adhesive. By incorporating the cast polypropylene base layer, the tape can effectively cooperate with the aluminum-plastic film. Testing shows that the battery cell can maintain high encapsulation strength after heat sealing. Furthermore, the inclusion of the polyolefin adhesive layer provides good electrolyte resistance. Testing shows that even after immersion in electrolyte following heat sealing, the battery cell still maintains high encapsulation strength and strong stability. This battery cell tape, battery cell, and secondary battery have a simple structure, are easy to manufacture, and can effectively encapsulate the battery cell for a long period after heat sealing, preventing leakage problems. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a cross-sectional schematic diagram of a battery cell tape according to an embodiment of this application;

[0017] Figure 2 This is a schematic diagram of the structure of a battery cell in an embodiment of this application;

[0018] Figure 3 This is a schematic diagram of an experiment involving heat sealing of the tape in an embodiment of this application.

[0019] Reference numerals: 1. Adhesive tape; 1-1. Base layer; 1-2. Adhesive layer; 1-3. Impregnated through-hole; 1-4. Identification pattern; 2. Electrode assembly; 3. Aluminum-plastic film; 4. End cap. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0021] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0022] Adhesive tape is a basic component of battery cells. During the battery cell manufacturing process, the wound body of cylindrical or prismatic battery cells needs to be bound with adhesive tape to fix it and form an electrode assembly. For the stacked body of pouch battery cells, adhesive tape is used to glue the stacked body around the edges to reinforce and seal the entire stacked body to form an electrode assembly.

[0023] After the electrode assembly is sealed on the side and top of the aluminum-plastic film, it will undergo an electrolyte injection process. During the electrolyte injection, the electrolyte may impact the tape inside the cell. After being soaked in the electrolyte, the tape's adhesion will also decrease. The tape may float to the final sealing position due to buoyancy. Thus, when the cell is finally sealed, the tape or some of the material on the tape will remain between the aluminum-plastic film, resulting in insufficient final sealing strength and causing the cell to leak.

[0024] Specifically, the base material of the internal tape of the battery cell is currently polyethylene terephthalate (PET), while the heat-sealing layer of the aluminum-plastic film is polypropylene (PP). The final sealing temperature of the battery cell is around 185°C. At this temperature, PP can melt and heat-seal the aluminum-plastic film. However, PET will not melt and heat-seal with PP at this temperature, resulting in poor sealing and posing a risk of leakage to the battery cell.

[0025] In addition, the adhesive layer of the tape inside the battery cell is mostly made of polyacrylic acid adhesive. Polyacrylic acid is not resistant to electrolyte. Even if the PET in the aforementioned aluminum-plastic film is replaced with other materials so that the aluminum-plastic film and tape can be temporarily heat-sealed, the polyacrylic acid will swell after being soaked in electrolyte, thereby reducing the sealing strength between the aluminum-plastic film and causing the battery cell to leak.

[0026] In addition, during the filling of electrolyte or when the battery cell is subjected to external vibration, some of the adhesive on the tape may fall off. The fallen adhesive will spread to the sealing point and be sealed together with the aluminum-plastic film. Even if the aluminum-plastic film is not heat-sealed together with the tape, during the long-term storage of the battery cell, the presence of liquid-sensitive polyacrylic acid at the heat-sealed area will cause structural instability and create weak points, resulting in a continuous decrease in heat-sealing strength and a risk of leakage.

[0027] The following describes specific embodiments in conjunction with the appendix. Figures 1 to 3 The technical solution of this application will be further described in detail.

[0028] In some embodiments of this application, a battery cell tape 1 is provided. The tape 1 includes a base layer 1-1 and an adhesive layer 1-2 stacked together. The base layer 1-1 includes cast polypropylene, and the adhesive layer 1-2 includes polyolefin adhesive.

[0029] like Figure 1 The diagram shows a cross-sectional view of an adhesive tape 1. The adhesive tape 1 includes a base layer 1-1 and an adhesive layer 1-2 stacked together. The adhesive layer 1-2 can be formed on the base layer 1-1 by casting or coating processes, and the specific process is not limited. The base layer 1-1 can play a supporting role, and the adhesive layer 1-2 can play an adhesive role.

[0030] The base layer 1-1 comprises cast polypropylene (CPP). The melting point of the base layer 1-1 is 125℃ to 175℃, for example, 125℃, 130℃, 150℃, or 175℃, etc., without specific limitation, to ensure heat sealing effect. The tape 1, using the cast polypropylene base layer 1-1, can be melt-sealed together with the aluminum-plastic film 3. Testing has shown that high sealing strength is ensured after heat sealing of the battery cell. Even if the tape 1 is present between the aluminum-plastic film 3, it will not affect the heat sealing effect of the battery cell, avoiding leakage problems.

[0031] Adhesive layer 1-2 comprises a polyolefin adhesive, which includes an adhesive and some additives. The adhesive contains one or more olefin monomer polymers, such as polypropylene, polyethylene, or polybutene. The additives include activators, stabilizers, or fillers. The melting point of adhesive layer 1-2 is 50℃ to 160℃, for example, 50℃, 70℃, 100℃, 130℃, or 160℃, etc., without specific limitation, to ensure heat sealing effect. By using polyolefin adhesive layer 1-2, tape 1 exhibits good electrolyte resistance. Tests have shown that after heat sealing of the battery cell and immersion in electrolyte, it still maintains high encapsulation strength, strong structural stability, and avoids leakage problems.

[0032] The tape 1 used for the battery cell has a simple structure and is easy to manufacture. It can effectively seal the battery cell for a long time after heat sealing, avoiding the leakage problem of soft-pack battery cells. The tape 1 can also be used for bonding cylindrical battery cells or prismatic hard-shell battery cells, and there are no specific limitations.

[0033] In some embodiments, the thickness of the base layer 1-1 is greater than the thickness of the adhesive layer 1-2.

[0034] like Figure 1 As shown, the thickness of the base layer 1-1 is greater than the thickness of the adhesive layer 1-2, so that the base layer 1-1 can provide sufficient support and achieve a good forming effect for the tape 1.

[0035] In some embodiments, the thickness of the base layer 1-1 is 10 μm to 70 μm, and the thickness of the adhesive layer 1-2 is 0.5 μm to 30 μm.

[0036] The thickness of the base layer 1-1 is 10μm to 70μm, for example, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm or 70μm, etc., and there is no specific limitation. This ensures the structural stability of the tape 1 and avoids the base layer 1-1 being too thick, or too thick in some areas, which would affect the overall battery assembly effect. It also avoids the base layer 1-1 being too thin, which would result in poor support.

[0037] The thickness of adhesive layer 1-2 is 0.5μm to 30μm, for example, 0.5μm, 1μm, 5μm, 10μm, 15μm, 20μm or 30μm, etc., and there is no specific limitation. This ensures the bonding effect of tape 1 and avoids adhesive layer 1-2 being too thick, which would affect the overall battery assembly effect, and also avoids adhesive layer 1-2 being too thin, which would result in insufficient bonding strength.

[0038] In some embodiments, the thickness of the base layer 1-1 is 30 μm, and the thickness of the adhesive layer 1-2 is 15 μm.

[0039] Tests showed that when the thickness of the base layer 1-1 of tape 1 was 30μm and the thickness of the adhesive layer 1-2 was 15μm, the sealing strength between the aluminum-plastic film 3 was the highest after the tape 1 and the aluminum-plastic film 3 were heat-sealed. Furthermore, the sealing strength between the aluminum-plastic film 3 remained the highest even after the tape 1 was immersed in the electrolyte.

[0040] In some embodiments, at least one wetting through hole 1-3 is provided on the surface of the tape 1, and the diameter of the wetting through hole 1-3 is 0.1 mm to 2 mm.

[0041] like Figure 2 The diagram shows a schematic of a battery cell. In the diagram, the L direction is the length direction of the battery cell, the W direction is the width direction of the battery cell, and the tape 1 is attached to the electrode assembly 2 of the battery cell. The surface of the tape 1 is provided with multiple arrayed wetting holes 1-3. By setting the wetting holes 1-3, the electrode assembly 2 can be fully wetted with the electrolyte to ensure the performance of the battery cell.

[0042] The diameter of the impregnation holes 1-3 is 0.1mm to 2mm, such as 0.1mm, 0.5mm, 1mm or 2mm, etc., and there is no specific limitation. This is to ensure the impregnation effect, avoid the diameter being too large, which would reduce the strength of tape 1, and also avoid the diameter being too small, which would result in poor electrolyte impregnation.

[0043] In some embodiments, the base layer 1-1 has a marking pattern 1-4 on the side away from the adhesive layer 1-2, and the marking pattern 1-4 has a length of 4mm to 10mm and a width of 4mm to 10mm.

[0044] like Figure 2 As shown, the tape 1 has a marking pattern 1-4, which can be formed on the base layer 1-1 by engraving or inkjet printing to serve as an identification. The length or width of the marking pattern 1-4 is 4mm to 10mm, such as 4mm, 5mm, 6mm, 8mm or 10mm, etc., and there is no specific limitation. This is to avoid the size being too large, which would affect the strength of the tape 1, and also to avoid the size being too small, which would make the marking pattern 1-4 difficult to identify.

[0045] Example 1

[0046] Two layers of aluminum-plastic film 3 are provided, and adhesive tape 1 is bonded between the two layers of aluminum-plastic film 3. Adhesive tape 1 includes adhesive layer 1-2 and base layer 1-1. Base layer 1-1 is CPP with a thickness of 10μm, and adhesive layer 1-2 is polyolefin adhesive with a thickness of 5μm.

[0047] Example 2

[0048] Two layers of aluminum-plastic film 3 are provided, and adhesive tape 1 is bonded between the two layers of aluminum-plastic film 3. Adhesive tape 1 includes adhesive layer 1-2 and base layer 1-1. Base layer 1-1 is CPP with a thickness of 30μm, and adhesive layer 1-2 is polyolefin adhesive with a thickness of 15μm.

[0049] Example 3

[0050] Two layers of aluminum-plastic film 3 are provided, and adhesive tape 1 is bonded between the two layers of aluminum-plastic film 3. Adhesive tape 1 includes adhesive layer 1-2 and base layer 1-1. Base layer 1-1 is CPP with a thickness of 70μm, and adhesive layer 1-2 is polyolefin adhesive with a thickness of 30μm.

[0051] Comparative Example 1

[0052] Two layers of aluminum-plastic film 3 are provided, with adhesive tape 1 not bonded between the two layers of aluminum-plastic film 3.

[0053] Comparative Example 2

[0054] Two layers of aluminum-plastic film 3 are provided, and adhesive tape 1 is bonded between the two layers of aluminum-plastic film 3. Adhesive tape 1 includes adhesive layer 1-2 and base layer 1-1. Base layer 1-1 is PET with a thickness of 10μm, and adhesive layer 1-2 is acrylic with a thickness of 5μm.

[0055] Comparative Example 3

[0056] Two layers of aluminum-plastic film 3 are provided, and adhesive tape 1 is bonded between the two layers of aluminum-plastic film 3. Adhesive tape 1 includes adhesive layer 1-2 and base layer 1-1. Base layer 1-1 is PET with a thickness of 10μm, and adhesive layer 1-2 is polyolefin adhesive with a thickness of 5μm.

[0057] Comparative Example 4

[0058] Two layers of aluminum-plastic film 3 are provided, and adhesive tape 1 is bonded between the two layers of aluminum-plastic film 3. Adhesive tape 1 includes adhesive layer 1-2 and base layer 1-1. Base layer 1-1 is CPP with a thickness of 10μm, and adhesive layer 1-2 is acrylic with a thickness of 5μm.

[0059] Comparative Example 5

[0060] Two layers of aluminum-plastic film 3 are provided, and adhesive tape 1 is bonded between the two layers of aluminum-plastic film 3. Adhesive tape 1 includes adhesive layer 1-2 and base layer 1-1. Base layer 1-1 is BOPP (biaxially oriented polypropylene) with a thickness of 10μm, and adhesive layer 1-2 is polyolefin adhesive with a thickness of 5μm.

[0061] Comparative Example 6

[0062] Two layers of aluminum-plastic film 3 are provided, and adhesive tape 1 is bonded between the two layers of aluminum-plastic film 3. Adhesive tape 1 includes adhesive layer 1-2 and base layer 1-1. Base layer 1-1 is OPP (oriented polypropylene) with a thickness of 10μm, and adhesive layer 1-2 is polyolefin adhesive with a thickness of 5μm.

[0063] Heat sealing tests were conducted on the two-layer aluminum-plastic film 3 of Examples 1 to 3 and Comparative Examples 1 to 6. The heat sealing method was as follows: Figure 3 As shown, the heat-sealing temperature was 190℃, the heat-sealing pressure was 0.3MPa, and the heat-sealing time was 3s. Immediately after heat-sealing, the encapsulation strength between the aluminum-plastic films 3 in each embodiment and comparative example was tested. The test method was to take the heat-sealed aluminum-plastic film 3, cut an 8mm wide sample perpendicular to the heat-sealed edge, place the sample on a tensile testing machine, and stretch it at a rate of 100mm / min to obtain the peel strength, which is the encapsulation strength between the aluminum-plastic films 3. In addition, after heat-sealing, the two layers of aluminum-plastic films 3 in each embodiment and comparative example were immersed in an electrolyte at 85℃ for 24h, and then the encapsulation strength between the aluminum-plastic films 3 was tested. The test method was the same as the above method. If the encapsulation strength tested immediately after heat-sealing was 0, the encapsulation strength test after immersion in the electrolyte could be omitted. The data was recorded using " / ". The specific test results are shown in Table 1.

[0064] Table 1 Heat Sealing Test Table

[0065]

[0066]

[0067] As shown in Table 1, when the base layer 1-1 of tape 1 is set to CPP, high encapsulation strength can be ensured without affecting the heat sealing effect. On this basis, when the adhesive layer 1-2 of tape 1 is set to polyolefin adhesive, the battery cell can still maintain high encapsulation strength after being immersed in electrolyte after heat sealing, and the structure is highly stable. On this basis, when the thickness of the base layer 1-1 of tape 1 is 30μm and the thickness of the adhesive layer 1-2 is 15μm, the encapsulation strength between the aluminum-plastic films 3 is the highest.

[0068] In some embodiments of this application, a battery cell is provided, including at least one electrode assembly 2, the surface of which is adhered with an adhesive tape 1 as described in any of the above embodiments.

[0069] The battery cell includes one or more electrode assemblies 2, and the surface of the electrode assembly 2 is attached with the aforementioned adhesive tape 1. The battery cell has good heat sealing effect, strong stability, and long service life.

[0070] In some embodiments of this application, a secondary battery is provided, including the battery cell as described in any of the above embodiments.

[0071] Secondary batteries, such as battery modules or battery packs, can be used in electrical devices, including vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles. Spacecraft include airplanes, rockets, space shuttles, and spacecraft. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers.

[0072] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this application (including the claims) is limited to these examples; within the framework 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 the embodiments of this application as described above, which are not provided in the details for the sake of brevity.

[0073] Furthermore, given that details have been set forth to describe exemplary embodiments of this application, it will be apparent to those skilled in the art that embodiments of this application may be practiced without these details or with variations thereof. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0074] Although this application has been described in conjunction with embodiments thereof, many substitutions, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description.

[0075] The embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included within the protection scope of this application.

Claims

1. A type of adhesive tape for battery cells, characterized in that, The tape comprises a base layer and an adhesive layer stacked together, wherein the base layer comprises cast polypropylene and the adhesive layer comprises polyolefin adhesive.

2. The tape according to claim 1, characterized in that, The thickness of the base layer is greater than the thickness of the adhesive layer.

3. The tape according to claim 1, characterized in that, The thickness of the base layer is 10 μm to 70 μm, and the thickness of the adhesive layer is 0.5 μm to 30 μm.

4. The tape according to claim 3, characterized in that, The thickness of the base layer is 30 μm, and the thickness of the adhesive layer is 15 μm.

5. The tape according to claim 1, characterized in that, The surface of the tape is provided with at least one wetting hole, the diameter of which is 0.1 mm to 2 mm.

6. The tape according to claim 1, characterized in that, The base layer has a marking pattern on the side away from the adhesive layer, and the marking pattern has a length of 4mm to 10mm and a width of 4mm to 10mm.

7. The tape according to claim 1, characterized in that, The polyolefin adhesive includes polypropylene adhesive, polyethylene adhesive and / or polybutene adhesive.

8. The tape according to claim 1, characterized in that, The base layer has a melting point of 125°C to 175°C, and the adhesive layer has a melting point of 50°C to 160°C.

9. A battery cell, characterized in that, It includes at least one electrode assembly, the surface of which is adhered with the tape as described in any one of claims 1-8.

10. A secondary battery, characterized in that, Includes the battery cell described in claim 9.

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