Expansion tape used for battery packaging and its manufacturing method and application, secondary battery and power consumption device

Abstract

The present application provides an expansion tape 7 for packaging batteries, comprising a substrate 71, an expansion layer 72, and an undercoat layer 73. Here, the substrate 71 has a first surface and a second surface opposite to each other. The expansion layer 72 is provided on the first surface of the substrate 71. The expansion layer 72 includes an organic adhesive and a temperature expansion material. The temperature expansion material is a material that can undergo volume expansion through heat treatment. The undercoat layer 73 is provided on the second surface of the substrate 71. The undercoat layer 73 has adhesive properties.

Description

[Technical field]

[0001] The present application relates to the field of secondary batteries, and in particular to an expansion tape used in packaging batteries and its manufacturing method and application, secondary batteries and power consuming devices. [Background technology]

[0002] With the rapid development of the electric vehicle industry, the application rate of secondary batteries such as lithium-ion batteries in power energy storage power sources is increasing year by year, so the research of high-power secondary batteries is gradually heating up. In some emerging fields, there are higher requirements for secondary batteries. Currently, the high-power power batteries that are widely used are all hard case batteries, but the energy density is becoming higher and higher. In the long-term storage cycle process of the battery cell, the negative electrode plate expands due to charging and discharging, and in serious cases, it may break through the case, causing a safety accident. Therefore, the group margin of the battery should not be too high, so that there is a certain gap between the case and the bare cell, and the expansion tape can fill this gap, and at the same time, relieve the expansion stress of the plate and improve the safety performance of the battery. However, the expansion ratio of the conventional expansion tape is relatively small, making it difficult to meet the demand for low group margin of the battery. Summary of the Invention [Problem to be solved by the invention]

[0003] Based on the above problems, the present application provides an expansion tape and its manufacturing method and application for packaging batteries, secondary batteries and power consumption devices, which can meet the demand for low group margin of batteries. [Means for solving the problem]

[0004] In one aspect of the present application, there is provided an expansion tape for use in packaging batteries, the expansion tape comprising: a substrate having opposing first and second surfaces; an expansion layer provided on a first surface of the substrate, the expansion layer including an organic adhesive and a temperature expansion material, the temperature expansion material being a material capable of generating a volume expansion through a heat treatment; and an undercoat layer disposed on the second surface of the substrate and having adhesive properties.

[0005] The expansion tape used in packaging the battery according to the embodiment of the present application includes a substrate, an expansion layer, and an undercoat layer, the undercoat layer includes an organic adhesive and a temperature expansion material, the organic adhesive has swelling properties, and the temperature expansion material can undergo volume expansion through heat treatment. The expansion tape has a relatively large expansion ratio and can be used in packaging the secondary battery, completely filling the gap between the electrode assembly and the case, and meeting the demand for low group margin of the battery.

[0006] In some embodiments, the maximum ratio of the expanded thickness of the expansion tape to its initial unexpanded thickness is ≧5, optionally between 5 and 10. When the maximum ratio of the expanded thickness of the expansion tape to its initial unexpanded thickness is within the above range, the expansion tape has a relatively large expansion ratio and can expand to significantly fill the gap between the electrode assembly and the case.

[0007] In some embodiments, the initial unexpanded thickness of the expansion tape is 100 μm to 500 μm, and optionally 150 μm to 300 μm. The initial unexpanded thickness of the expansion tape is within the above range, and can fill most of the gap between the electrode assembly and the case after expansion, and can solve the filling problem between the electrode assembly and the case of a power battery with low group margin.

[0008] In some embodiments, the thickness of the expansion tape after expansion is 1 mm to 5 mm, and optionally 1 mm to 3 mm. The thickness of the expansion tape after expansion is within the above range, and can fill most of the gap between the electrode assembly and the case after expansion, and can solve the filling problem between the electrode assembly and the case of a power battery with low group margin.

[0009] In some embodiments, the compression ratio of the expansion tape after expansion is 10% to 75%, the compression ratio being the rate at which the thickness of the expansion tape after expansion is reduced by the action of a preset stress. The compression ratio of the expansion tape after expansion is within the above range, so that the expansion tape is compressed under the force during the battery cycle process, and can relieve the expansion stress during the cycle process of the electrode assembly.

[0010] In some embodiments, the ratio of the thickness of the substrate to the initial unexpanded thickness of the expansion tape is (2-10):100, optionally (3-6):100, and the ratio of the thickness of the substrate to the initial unexpanded thickness of the expansion tape is within the above range, and the expansion tape has suitable mechanical strength.

[0011] Optionally, the thickness of the substrate is between 5 μm and 30 μm, and optionally between 5 μm and 15 μm.

[0012] In some embodiments, the ratio of the initial unexpanded thickness of the intumescent layer to the initial unexpanded thickness of the intumescent tape is (75-97): 100, optionally (90-97): 100. When the ratio of the initial unexpanded thickness of the intumescent layer to the initial unexpanded thickness of the intumescent tape is within the above ranges, the intumescent tape has a relatively large expansion ratio.

[0013] Optionally, the thickness of the expandable layer is between 75 μm and 450 μm, and optionally between 100 μm and 200 μm.

[0014] In some embodiments, the ratio of the thickness of the undercoat layer to the initial unexpanded thickness of the expansion tape is (1-5):100, optionally (1.5-3):100; Optionally, the thickness of the undercoat layer is between 2.5 μm and 20 μm, and optionally between 2.5 μm and 7.5 μm.

[0015] In some embodiments, the mass ratio of the organic adhesive to the thermal expansion material in the expansion layer is (50-80):(20-50); Optionally, the mass content of the organic adhesive in the expansion layer is 50% to 80%, and the mass content of the temperature expansion material is 20% to 50%. The contents of the organic adhesive and the temperature expansion material in the expansion layer are within the above ranges, so that the expansion layer has relatively good swelling characteristics and temperature expansion characteristics, the expansion ratio of the expansion tape is relatively large, and adhesive extrusion is unlikely to occur.

[0016] In some embodiments, the swelling ratio of the organic adhesive is 50% to 200%, and the swelling ratio refers to the ratio of the volume of the organic adhesive when it is placed in the electrolyte to the volume of the dried organic adhesive. When the swelling ratio of the organic adhesive is within the above range, the organic adhesive in the expansion layer can absorb the electrolyte and expand during the packaging process of the secondary battery, and the expansion ratio of the expansion tape is relatively large.

[0017] In some embodiments, the organic adhesive has a glass transition temperature of −20° C. to 60° C. When the glass transition temperature of the organic adhesive is within the above range, the expansion tape has a relatively large expansion ratio and excellent mechanical properties.

[0018] In some embodiments, the initial expansion temperature of the temperature expansion material is 70° C. to 130° C., optionally 80° C. to 110° C. The initial expansion temperature of the temperature expansion material is within the above range, so that the expansion tape can be compatible with the conventional packaging process of secondary batteries and complete the temperature-responsive expansion process in the packaging process of secondary batteries, so that the expansion tape can expand synchronously with the packaging process of secondary batteries to fill the gap between the electrode plate and the case.

[0019] In some embodiments, the organic adhesive includes at least one of an acrylate adhesive, a methyl methacrylate adhesive, an acrylic adhesive, an ethylene-vinyl acetate adhesive, and a polypropylene adhesive, and optionally includes an acrylate adhesive, which has relatively good swelling and adhesive properties and can maintain a certain adhesive strength even after absorbing the electrolyte and expanding.

[0020] In some embodiments, the substrate material includes at least one of polyethylene terephthalate, polyimide, polypropylene, and polyethylene.

[0021] In some embodiments, the undercoat layer includes at least one of modified polypropylene, styrene-isoprene-styrene block copolymer, and hydrogenated styrene-butadiene-styrene block copolymer. The undercoat layer material has relatively good adhesion and electrolyte resistance, and is used in packaging of secondary batteries, and after injecting electrolyte, the undercoat layer still has relatively good adhesion and can avoid the falling off or displacement of the expansion tape.

[0022] In some embodiments, the expansion tape comprises: a layer of oriented polystyrene disposed on a surface of the expandable layer remote from the substrate; Alternatively, the ratio of the thickness of the oriented polystyrene layer to the thickness of the expansion tape is ≦20:100, and optionally (5 to 20):100; Optionally, the thickness of the oriented polystyrene layer is between 15 μm and 90 μm, and more optionally between 25 μm and 50 μm.

[0023] The oriented polystyrene layer has characteristics such as high strength, high rigidity, and stable shape. By placing the oriented polystyrene layer on the surface of the expansion layer away from the substrate, the stresses on the two surfaces of the expansion layer are nearly equal, so that the expansion tape is less likely to deform or wrap around after expansion.

[0024] According to a second aspect, the present application further provides a method for producing an expansion tape for use in packaging a battery, the method comprising the steps of: Producing an intumescent layer on one surface of a substrate; and forming an undercoat layer on a surface of the substrate remote from the intumescent layer.

[0025] The expansion tape manufactured by the expansion tape manufacturing method of the embodiment of the present application has swelling characteristics and temperature responsive expansion characteristics, and has a relatively large expansion ratio, which is particularly suitable for packaging secondary batteries and can meet the demand for low battery margins.

[0026] In some embodiments, the step of producing the expandable layer comprises: Mixing raw materials of an organic adhesive and a thermal expansion material to prepare a slurry precursor; A step of curing the slurry precursor to produce an expanded layer slurry; applying the expanding layer slurry to a surface of the substrate.

[0027] In some embodiments, the method of making the expansion tape includes: (1) The solid content of the expanded layer slurry is 10% to 50%; (2) The viscosity of the expansion layer slurry is 50 mPa·s to 500 mPa·s.

[0028] According to a third aspect, the present application further provides an application of the expanding tape of the first aspect in the manufacture of a battery.

[0029] According to a fourth aspect, the present application further provides a method for manufacturing a secondary battery, the method comprising: applying the undercoat layer of the expanding tape of the first aspect to a surface of an electrode assembly; placing the electrode assembly with the expansion tape attached thereto in a case and vacuum drying the same at 70°C to 130°C to primarily expand the expansion tape; sealing the case; and injecting an electrolyte into the sealed case, and allowing the expansion tape, which has undergone a primary expansion, to absorb the electrolyte and undergo a secondary expansion.

[0030] The manufacturing method for a secondary battery according to an embodiment of the present application uses the expansion tape of the first aspect described above, and installs the expansion tape during the packaging process of the secondary battery, so that the expansion tape expands synchronously during the packaging process of the secondary battery, thereby filling the gap between the electrode assembly and the case and meeting the demand for low margin of the battery. The manufacturing method for the secondary battery has a simple manufacturing process and a relatively low production cost.

[0031] According to a fifth aspect, the present application further provides a secondary battery, the secondary battery comprising: A case filled with an electrolyte; an electrode assembly disposed within the case; The expansion tape of the first aspect described above includes an expansion tape that is placed between the case and the electrode assembly and fills the gap between the case and the electrode assembly, and the undercoat layer of the expansion tape is attached to the surface of the electrode assembly.

[0032] In the secondary battery according to the embodiment of the present application, by disposing the expansion tape of the first aspect between the case and the electrode assembly, the gap between the case and the electrode assembly can be effectively filled, and the demand for low margin of the battery can be met.

[0033] According to a sixth aspect, the present application further provides a battery module including the secondary battery of the fifth aspect.

[0034] According to a seventh aspect, the present application further provides a battery pack including the battery module of the sixth aspect.

[0035] According to an eighth aspect, the present application further provides a power consuming device including at least one selected from the secondary battery of the fifth aspect, the battery module of the sixth aspect, or the battery pack of the seventh aspect.

[0036] The details of one or more embodiments of the application are set forth in the drawings and description which follow, and other features, objects and advantages of the application will become apparent from the description, drawings, and claims. [Brief description of the drawings]

[0037] [Figure 1] 1 is a schematic diagram showing the structure of an expansion tape according to an embodiment of the present application; [Diagram 2] FIG. 2 is a structural schematic diagram of an expansion tape according to another embodiment of the present application. [Diagram 3] 1 is a flowchart of a method for manufacturing an expansion tape according to one embodiment of the present application. [Figure 4] 1 is a schematic diagram of a secondary battery according to an embodiment of the present application; [Diagram 5] FIG. 5 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 4. [Figure 6] 2 is a flowchart of a method for manufacturing a secondary battery according to an embodiment of the present application. [Figure 7] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 8] 1 is a schematic diagram of a battery pack according to an embodiment of the present application; [Figure 9] FIG. 9 is an exploded view of the battery pack according to the embodiment of the present application shown in FIG. 8. [Figure 10] 1 is a schematic diagram of a power consumption device powered by a secondary battery according to an embodiment of the present application;

[0038] To better describe and explain the embodiments and / or examples of the invention disclosed herein, reference may be made to one or more drawings, in which additional details or examples for describing the drawings should not be considered as limiting the scope of the disclosed invention, either of the presently described embodiments and / or examples, or the best mode of these inventions as currently understood. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] In order to facilitate the understanding of the present application, the following will more fully describe the present application with reference to the accompanying drawings. The drawings show preferred embodiments of the present application. However, the present application may be embodied in many different forms and is not limited to the embodiments set forth herein. Rather, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and complete.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms used herein are for the purpose of describing specific examples only and are not intended to be limiting of this application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0041] Referring to FIG. 1, one embodiment of the present application provides an expanding tape 7 for use in packaging batteries, comprising a substrate 71 , an expanding layer 72 , and an undercoat layer 73 .

[0042] Here, the substrate 71 has opposing first and second surfaces.

[0043] The expansion layer 72 is provided on the first surface of the substrate 71. The expansion layer 72 includes an organic adhesive and a temperature expansion material. The temperature expansion material is a material that can undergo volume expansion through heat treatment.

[0044] The undercoat layer 73 is provided on the second surface of the substrate 71. The undercoat layer 73 has adhesive properties.

[0045] The expansion tape 7 used in packaging the battery includes a substrate 71, an expansion layer 72, and an undercoat layer 73, the undercoat layer 73 includes an organic adhesive and a temperature expansion material, the organic adhesive has swelling properties, and the temperature expansion material can generate volume expansion through heat treatment. The expansion tape 7 has a relatively large expansion ratio and can be used in packaging the secondary battery, and can completely fill the gap between the electrode assembly and the case.

[0046] In some embodiments, the maximum ratio of the thickness of the expansion tape 7 after expansion to its initial unexpanded thickness is ≧5. The maximum ratio of the thickness of the expansion tape 7 after expansion to its initial unexpanded thickness refers to the ratio of the maximum thickness of the expansion tape 7 after expansion to its initial unexpanded thickness. For example, the expansion tape 7 is expanded to its maximum thickness by the following process. The undercoat layer 73 of the expansion tape 7 is laminated on a substrate and its initial unexpanded thickness is measured, then the expansion tape 7 is heat-treated at 110° C. for 4 hours to expand it primarily, then the expanded expansion tape 7 is immersed in a conventional electrolyte for secondary batteries for 48 hours or more to expand it secondarily, and the expansion tape 7 is taken out and its thickness after expansion is measured, which is the maximum thickness of the expansion tape 7 after expansion. Specifically, the thickness of each state of the expansion tape 7 can be easily measured with a micrometer. The maximum ratio of the thickness of the expansion tape 7 after expansion to its initial unexpanded thickness is within the above range, and the expansion tape 7 has a relatively large expansion ratio and can expand to largely fill the gap between the electrode assembly and the case. Furthermore, the maximum ratio of the expanded thickness of the expansion tape 7 to its initial unexpanded thickness is 5 to 10. Alternatively, the maximum ratio of the expanded thickness of the expansion tape 7 to its initial unexpanded thickness may be within a range consisting of any of the values ​​5, 6, 7, 8, 9, or 10.

[0047] In some embodiments, the initial unexpanded thickness of the expansion tape 7 is 100 μm to 500 μm. The initial unexpanded thickness of the expansion tape 7 is within the above range, and can fill most of the gap between the electrode assembly and the case after expansion, and can solve the filling problem between the electrode assembly and the case of a power battery with low group margin. Alternatively, the initial unexpanded thickness of the expansion tape 7 may be within a range consisting of any of the values ​​of 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, or 500 μm. Furthermore, the initial unexpanded thickness of the expansion tape 7 is 150 μm to 300 μm.

[0048] In some embodiments, the thickness of the expansion tape 7 after expansion is 1 mm to 5 mm. The thickness of the expansion tape 7 after expansion is within the above range, and can fill most of the gap between the electrode assembly and the case after expansion, and can solve the filling problem between the electrode assembly and the case of a power battery with low group margin. Alternatively, the thickness of the expansion tape 7 after expansion may be within a range consisting of any of the numerical values ​​of 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm. Furthermore, the thickness of the expansion tape 7 after expansion is 1 mm to 3 mm.

[0049] In some embodiments, the compression ratio of the expansion tape 7 after expansion is 10% to 75%. The compression ratio refers to the ratio of the thickness of the expansion tape 7 after expansion to a preset stress. In the embodiment of the present application, the compression ratio of the expansion tape 7 after expansion can be tested by the following method. First, the thickness of the expansion tape 7 after expansion is measured, and then a pressure of 1.5 MPa is applied to one side surface of the expansion tape 7 near the undercoat layer 73 after expansion, and the thickness at that pressure is measured to calculate the compression ratio. The compression ratio of the expansion tape 7 after expansion is within the above range, and the expansion tape 7 after expansion is compressed under force during the cycle process of the secondary battery, thereby relieving the expansion stress during the cycle process of the electrode assembly. Alternatively, the compression ratio of the expansion tape 7 after expansion may be within a range consisting of any of the values ​​of 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 72% or 75%.

[0050] In some embodiments, the ratio of the thickness of the substrate 71 to the initial unexpanded thickness of the expansion tape 7 is (2-10):100. When the ratio of the thickness of the substrate 71 to the initial unexpanded thickness of the expansion tape 7 is within the above range, the expansion tape 7 has suitable mechanical strength. Furthermore, the ratio of the thickness of the substrate 71 to the initial unexpanded thickness of the expansion tape 7 is (3-6):100.

[0051] In some of the embodiments, the thickness of the substrate 71 is 5 μm to 30 μm. Alternatively, the thickness of the substrate 71 may be within a range of any of the following values: 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 20 μm, 25 μm, or 30 μm. Further, the thickness of the substrate 71 is 5 μm to 15 μm.

[0052] In some embodiments, the ratio of the initial unexpanded thickness of the expansion layer 72 to the initial unexpanded thickness of the expansion tape 7 is (75-97):100. When the ratio of the initial unexpanded thickness of the expansion layer 72 to the initial unexpanded thickness of the expansion tape 7 is within the above range, the expansion tape 7 has a relatively large expansion ratio. Furthermore, the ratio of the initial unexpanded thickness of the expansion layer 72 to the initial unexpanded thickness of the expansion tape 7 is (90-97):100.

[0053] In some of these embodiments, the thickness of the intumescent layer 72 is between 75 μm and 450 μm. Alternatively, the thickness of the intumescent layer 72 is between 75 μm, 80 μm, 90 μm, 100 μm, 120 μm, 150 μm, 160 μm, 180 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, or 450 μm. Additionally, the thickness of the intumescent layer 72 is between 100 μm and 200 μm.

[0054] In some of the embodiments, the ratio of the thickness of the undercoat layer 73 to the initial unexpanded thickness of the expansion tape 7 is (1-5):100. Furthermore, the ratio of the thickness of the undercoat layer 73 to the initial unexpanded thickness of the expansion tape 7 is (1.5-3):100. The undercoat layer 73 has adhesive properties and can be attached to the surface of the electrode assembly during the packaging process of the secondary battery. By controlling the thickness of the undercoat layer 73 within the above range, the expansion tape 7 can achieve a relatively good adhesive effect.

[0055] In some embodiments, the thickness of the undercoat layer 73 is between 2.5 μm and 20 μm. Alternatively, the thickness of the undercoat layer 73 is between 2.5 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 7.5 μm, 8 μm, 10 μm, 12 μm, 14 μm, 15 μm, 16 μm, 18 μm, or 20 μm. Additionally, the thickness of the undercoat layer 73 is between 2.5 μm and 7.5 μm.

[0056] In some embodiments, the mass ratio of the organic adhesive and the temperature expansion material in the expansion layer 72 is (50-80):(20-50). When the mass ratio of the organic adhesive and the temperature expansion material in the expansion layer 72 is within the above range, the expansion layer 72 has relatively good swelling characteristics and temperature expansion characteristics, the expansion ratio of the expansion tape 7 is relatively large, and the adhesive is unlikely to protrude.

[0057] In some embodiments, the weight content of the organic adhesive in the expansion layer 72 is 50%-80% and the weight content of the thermal expansion material is 20%-50%. Alternatively, the weight content of the organic adhesive in the expansion layer 72 may be within the range of any of the following values: 50%, 55%, 60%, 65%, 70%, 75%, or 80%. The weight content of the thermal expansion material in the expansion layer 72 may be within the range of any of the following values: 20%, 25%, 30%, 35%, 40%, 45%, or 50%.

[0058] In some embodiments, the swelling ratio of the organic adhesive is 50% to 200%. The swelling ratio refers to the ratio of the volume of the organic adhesive placed in the electrolyte to the volume of the dried organic adhesive. When the swelling ratio of the organic adhesive is within the above range, the organic adhesive in the expansion layer 72 can absorb the electrolyte and expand during the packaging process of the secondary battery, and the expansion ratio of the expansion tape 7 is relatively large. Alternatively, the swelling ratio of the organic adhesive may be within a range of any of the following values: 50%, 60%, 70%, 80%, 90%, 100%, 120%, 140%, 150%, 160%, 180%, or 200%.

[0059] In some embodiments, the glass transition temperature of the organic adhesive is -20°C to 60°C. The glass transition temperature is the temperature at which the organic adhesive transitions from a highly elastic state to a glassy state. At or above this temperature, the organic adhesive exhibits elasticity, and at this temperature, the organic adhesive exhibits brittleness. The glass transition temperature of the organic adhesive can be measured by a test method known in the art, such as a dilatometer method, a refractive index method, a thermomechanical method, a differential thermal analysis (DTA) method, a dynamic mechanical property analysis (DMA) method, a nuclear magnetic resonance (NMR) method, etc. The glass transition temperature of the organic adhesive is within the above range, and the expansion tape has a relatively large expansion ratio and excellent mechanical properties. Optionally, the glass transition temperature of the organic adhesive may be within a range consisting of any of the values ​​of -20°C, -10°C, 0°C, 5°C, 10°C, 20°C, 30°C, 40°C, 50°C, or 60°C.

[0060] In some embodiments, the initial expansion temperature of the temperature expansion material is 70°C to 130°C. The initial expansion temperature of the temperature expansion material refers to the temperature at which the temperature expansion material begins to expand. The initial expansion temperature of the temperature expansion material is within the above range, and the expansion tape 7 can match with the conventional packaging process of secondary batteries, and complete the temperature-responsive expansion process in the packaging process of secondary batteries, so that the expansion tape 7 can expand synchronously in the packaging process of secondary batteries to fill the gap between the electrode plate and the case. Alternatively, the initial expansion temperature of the temperature expansion material may be within a range consisting of any of the values ​​of 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or 130°C. Furthermore, the initial expansion temperature of the temperature expansion material is 80°C to 110°C.

[0061] In some embodiments, the organic adhesive includes at least one of an acrylate adhesive, a methyl methacrylate adhesive, an acrylic adhesive, an ethylene-vinyl acetate adhesive, and a polypropylene adhesive. Optionally, the organic adhesive includes an acrylate adhesive. The organic adhesive has relatively good swelling and adhesive properties and can maintain a certain adhesive strength even after absorbing the electrolyte and expanding.

[0062] In some embodiments, the temperature-expandable material includes at least one of expanded microspheres and polyurethane. The initial expansion temperature and expansion ratio of the temperature-expandable material are suitable, and the expansion tape 7 has a relatively large expansion ratio. Optionally, the temperature-expandable material includes expanded microspheres. Expanded microspheres are thermoplastic hollow polymeric microspheres, consisting of a thermoplastic polymer shell and an enclosed liquid alkane gas. Upon heating, the gas pressure within the shell increases and the thermoplastic shell softens, thereby significantly increasing the volume of the expanded microsphere. Upon cooling, the shell of the expanded microsphere hardens again and the volume is fixed.

[0063] In some embodiments, the expanded microspheres may be at least one selected from 551DU40, 461DU20, 461DU40, 031DU40, 053DU40, 007WUF20, and 031WUF20 of the EXPANCEL series of Akzo Nobel Co. The above expanded microspheres have a more suitable initial expansion temperature.

[0064] In some embodiments, the expansion layer 72 further optionally includes a thickener. For example, the thickener may include at least one of a C5 petroleum resin, a C9 petroleum resin, a hydrocarbon petroleum resin, and a dicyclopentadiene DCPD resin. Further, the mass content of the thickener in the expansion layer 72 is 5% to 30%.

[0065] In some embodiments, the expandable layer 72 further optionally includes an antioxidant, and the mass content of the antioxidant in the expandable layer 72 is between 0.5% and 2%.

[0066] In some embodiments, the material of the substrate 71 includes at least one of polyethylene terephthalate (PET), polyimide (PI), polypropylene (PP), and polyethylene.

[0067] In some embodiments, the undercoat layer 73 includes at least one of modified polypropylene, styrene-isoprene-styrene block copolymer (SIS), and hydrogenated styrene-butadiene-styrene block copolymer (SEBS). The material of the undercoat layer 73 has relatively good adhesion and electrolyte resistance, and is used in packaging of secondary batteries. After injecting the electrolyte, the undercoat layer 73 still has relatively good adhesion and can avoid the falling off or displacement of the expansion tape 7.

[0068] 2, in some embodiments, the expansion tape 7 further includes an oriented polystyrene layer. The oriented polystyrene layer is disposed on the surface of the expansion layer 72 that is remote from the substrate 71. Oriented polystyrene (OPS) has characteristics such as high strength, high rigidity, and shape stability, and by disposing the oriented polystyrene layer on the surface of the expansion layer 72 that is remote from the substrate 71, the stresses on the two surfaces of the expansion layer 72 are nearly equal, so that the expansion tape 7 is less likely to deform or wind after expansion.

[0069] In some embodiments, the ratio of the thickness of the oriented polystyrene layer to the thickness of the expansion tape 7 is ≦20:100. When the thickness of the oriented polystyrene layer is in the above range, the expansion tape 7 has appropriate mechanical strength, and the expansion tape 7 after expansion is less likely to deform and wind. Furthermore, the ratio of the thickness of the oriented polystyrene layer to the thickness of the expansion tape 7 is (5-20):100.

[0070] In some embodiments, the thickness of the oriented polystyrene layer is between 15 μm and 90 μm. Alternatively, the thickness of the oriented polystyrene layer is between 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 60 μm, 70 μm, 80 μm, or 90 μm. Additionally, the thickness of the oriented polystyrene layer is between 25 μm and 50 μm.

[0071] Referring to FIG. 3, another embodiment of the present application further provides a manufacturing method for an expansion tape 7 used for packaging a battery, the manufacturing method including steps S110 to S120 of manufacturing the expansion tape 7 of the above-mentioned first aspect as follows.

[0072] S110: An expansion layer 72 is produced on one surface of the substrate 71.

[0073] S120: An undercoat layer 73 is produced on the surface of the substrate 71 away from the expansion layer 72.

[0074] The expansion tape 7 manufactured by the above-mentioned method for manufacturing the expansion tape 7 has swelling properties and temperature responsive expansion properties, and the expansion ratio of the expansion tape 7 is relatively large, making it particularly suitable for packaging secondary batteries.

[0075] In some embodiments, step S110 includes the following steps.

[0076] S111: Mixing an organic adhesive raw material and a thermal expansion material to produce a slurry precursor. In some embodiments, the organic adhesive raw material includes an adhesive base and a hardener. Optionally, the adhesive base includes at least one of methyl methacrylate, vinyl acetate, ethyl acrylate, acrylic ester, and acrylonitrile.

[0077] In some embodiments, step S111 further includes mixing a solvent and other optional ingredients (e.g., a thickener and an antioxidant) with the organic adhesive ingredients and the thermal expansion material. Specifically, the solvent includes at least one of ethyl acetate, toluene, and xylene.

[0078] S112: The slurry precursor is subjected to a curing reaction to produce the expansion layer 72 slurry.

[0079] S113: The slurry for the expansion layer 72 is applied onto the surface of the substrate 71.

[0080] In some of these embodiments, the solids content of the expansion layer 72 slurry is between 10% and 50%.

[0081] In some embodiments, the viscosity of the expandable layer 72 slurry is between 50 mPa·s and 500 mPa·s.

[0082] In some embodiments, step S110 weighs out the solvent, adhesive base, curing agent, temperature expansion material, and other optional components according to the specific preset components of the expansion layer 72. The weighed out solvent, adhesive base, temperature expansion material, and other optional components are then uniformly stirred under vacuum to produce a slurry precursor. The curing agent is then added to the slurry precursor and the mixture is stirred under vacuum for 10 to 20 minutes to produce a slurry of the expansion layer 72. The produced expansion layer 72 slurry is uniformly applied to the first surface of the substrate 71 to produce the expansion layer 72.

[0083] In addition, the secondary battery, the battery module, the battery pack, and the power consuming device of the present application will be described below with appropriate reference to the drawings.

[0084] In one embodiment of the present application, a secondary battery is provided.

[0085] Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During charging and discharging of the battery, active ions shuttle between the positive electrode plate and the negative electrode plate to be absorbed and released. The electrolyte serves to conduct ions between the positive electrode plate and the negative electrode plate. The separator is installed between the positive electrode plate and the negative electrode plate, and serves mainly to prevent short circuit between the positive and negative electrodes, while allowing ions to pass through.

[0086] [Positive electrode plate] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including the positive electrode active material of the first aspect of the present application.

[0087] For example, the positive electrode current collector has two opposing surfaces in the thickness direction of the positive electrode current collector, and the positive electrode film layer is disposed on either one or both of the two opposing surfaces of the positive electrode current collector.

[0088] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, an aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0089] In some embodiments, when the secondary battery is a lithium ion battery, the positive electrode active material may adopt a positive electrode active material used in lithium ion batteries known in the art. For example, the positive electrode active material may include at least one of materials of lithium-containing phosphate with an olivine structure, lithium transition metal oxide, and respective modified compound. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of the lithium transition metal oxide include lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (may be abbreviated as LiNi 0.5 Co 0.2 Mn 0.3O2(NCM 523 (may be abbreviated as LiNi 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (may be abbreviated as LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (may be abbreviated as LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM 811 Lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 Examples of the lithium-containing phosphate having an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0090] In some embodiments, when the secondary battery is a sodium ion battery, the positive electrode active material may be a positive electrode active material known in the art for use in sodium ion batteries. For example, these positive electrode active materials may be used alone or in combination of two or more. Here, the positive electrode active material may be sodium iron composite oxide (NaFeO2), sodium cobalt composite oxide (NaCoO2), sodium chromium composite oxide (NaCrO2), sodium manganese composite oxide (NaMnO2), sodium nickel composite oxide (NaNiO2), sodium nickel titanium composite oxide (NaNi 1 / 2 Ti 1 / 2 O2), sodium nickel manganese composite oxide (NaNi 1 / 2 Mn 1 / 2 O2), sodium iron manganese oxide (Na 2 / 3 Fe 1 / 3Mn 2 / 3 O2), sodium nickel cobalt manganese composite oxide (NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2), sodium iron phosphate compound (NaFePO4), sodium manganese phosphate compound (NaMnPO4), sodium cobalt phosphate compound (NaCoPO4), Prussian blue-based materials, polyanion materials (phosphates, fluorophosphates, pyrophosphates, sulfates), and the like, but the present application is not limited to these materials, and the present application may further use other conventionally known materials that can be used as the positive electrode active material of a sodium ion battery.

[0091] In some embodiments, the positive electrode membrane layer optionally further comprises an adhesive, which may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic ester resin.

[0092] In some embodiments, the positive electrode membrane layer optionally further comprises a conductive agent, which may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, by way of example.

[0093] In some embodiments, the positive electrode plate can be manufactured in the following manner: The components for manufacturing the positive electrode plate, such as the positive electrode active material, the conductive agent, the adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then applied onto a positive electrode current collector, and the positive electrode plate is obtained after processes such as drying and cold pressing.

[0094] [Negative electrode plate] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0095] For example, the negative electrode current collector has two opposing surfaces in the thickness direction of the negative electrode current collector, and the negative electrode film layer is disposed on either one or both of the two opposing surfaces of the negative electrode current collector.

[0096] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, a copper foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0097] In some embodiments, the negative electrode active material may be a negative electrode active material for a battery known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicone-based material, a tin-based material, and lithium titanate. The silicone-based material may be at least one selected from a silicone element, a silicone oxide, a silicone carbon composite, a silicone nitrogen composite, and a silicone alloy. The tin-based material may be at least one selected from a tin element, a tin oxide, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery negative electrode active material may be used. These negative electrode active materials may be used alone or in combination of two or more.

[0098] In some embodiments, the negative electrode membrane layer optionally further comprises an adhesive, which may be at least one selected from styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0099] In some embodiments, the negative electrode membrane layer optionally further comprises a conductive agent, which may be at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0100] In some embodiments, the negative electrode membrane layer optionally further comprises other auxiliary agents, such as a thickening agent (eg, sodium carboxymethylcellulose (CMC-Na)).

[0101] In some embodiments, the negative electrode plate can be manufactured in the following manner: Components for manufacturing the negative electrode plate, such as a negative electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, which is then applied onto a negative electrode current collector, and the negative electrode plate is obtained after processes such as drying and cold pressing.

[0102] [Separator] In some embodiments, the secondary battery further includes a separator. The present application is not particularly limited to the type of separator, and any known porous structure separator having good chemical stability and mechanical stability may be selected.

[0103] In some embodiments, the material of the separator may be at least one selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, and is not particularly limited.

[0104] In some embodiments, the positive and negative plates and the separator may be wound or stacked to form an electrode assembly.

[0105] [Electrolyte] The electrolyte serves to conduct ions between the positive and negative electrodes. The present application is not specifically limited to the type of electrolyte, and may be selected according to need. For example, the electrolyte may be liquid, gel, or all solid.

[0106] In some embodiments, the electrolyte is an electrolytic solution, the electrolytic solution including an electrolyte salt and a solvent.

[0107] In some embodiments, the electrolyte salt may be at least one selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, bisfluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0108] In some embodiments, the solvent may be at least one selected from ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0109] In some embodiments, the electrolyte solution may further include optional additives. For example, the additives may include an anode film-forming additive, a cathode film-forming additive, and may further include additives that can improve some performance of the battery, such as an additive that improves the overcharge performance of the battery, an additive that improves the high temperature or low temperature performance of the battery, etc.

[0110] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0111] In some embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0112] The present application is not particularly limited to the shape of the secondary battery, which may be cylindrical, rectangular or any other shape. For example, FIG. 4 shows a secondary battery 5 having a rectangular structure as an example.

[0113] In some embodiments, referring to FIG. 5, the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and a side plate connected on the bottom plate, and the bottom plate and the side plate surround and form a receiving cavity. The case 51 has an opening communicating with the receiving cavity, and the cover plate 53 can cover the opening to seal the receiving cavity. The positive electrode plate, the negative electrode plate and the separator may form an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. An electrolyte is infiltrated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and can be selected by those skilled in the art according to specific actual needs.

[0114] Another embodiment of the present application further provides a secondary battery 5 including a case 51, an electrode assembly 52, and the expansion tape 7 of the first embodiment described above.

[0115] Here, the case 51 is filled with an electrolyte. The electrode assembly 52 is installed in the case. The expansion tape 7 is installed between the case 51 and the electrode assembly 52 and fills the gap between the case 51 and the electrode assembly 52. ​​The undercoat layer 73 of the expansion tape 7 is attached to the surface of the electrode assembly 52.

[0116] Referring to FIG. 6, an embodiment of the present application further provides a method for manufacturing a secondary battery 5, which includes the following steps S210 to S240.

[0117] S210: The undercoat layer 73 of the expansion tape 7 of the first embodiment is attached to the surface of the electrode assembly 52.

[0118] S220: The electrode assembly 52 with the expansion tape 7 attached is placed in a case and vacuum dried at 70°C to 130°C to primarily expand the expansion tape 7. In step S220, the electrode assembly 52 is placed in the case 51 and vacuum dried at 70°C to 130°C to remove water and oxygen from the electrode assembly 52 and the case 51, and the temperature expansion material in the expansion tape 7 expands synchronously during this process, thereby primarily expanding the expansion tape 7.

[0119] S230: Seal the case 51. Specifically, in step S230, the cover plate 53 is placed over the opening of the case 51 to seal the case 51.

[0120] S240: An electrolyte is injected into the sealed case 51, and the expansion tape 7 that has undergone the primary expansion is caused to absorb the electrolyte and undergo secondary expansion. In step S240, the organic adhesive in the expansion tape 7 absorbs the electrolyte and swells, thereby allowing the expansion tape 7 to undergo secondary expansion.

[0121] The manufacturing method for the secondary battery 5 uses the expansion tape 7 of the first embodiment, and by installing the expansion tape 7 in the packaging process of the secondary battery, the expansion tape 7 expands synchronously in the packaging process of the secondary battery, thereby filling the gap between the electrode assembly and the case, and the manufacturing method for the secondary battery has a simple manufacturing process and a relatively low production cost.

[0122] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, with the specific number being selectable by one skilled in the art depending on the application and capacity of the battery module.

[0123] Fig. 7 shows an example of a battery module 4. Referring to Fig. 7, in the battery module 4, the multiple secondary batteries 5 may be arranged in sequence along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the multiple secondary batteries 5 may be fixed by fasteners.

[0124] Optionally, the battery module 4 may further include a housing having an accommodating space, and the multiple secondary batteries 5 are accommodated in the accommodating space.

[0125] In some embodiments, the battery modules may be assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, with the specific number being selectable by one skilled in the art depending on the application and capacity of the battery pack.

[0126] 8 and 9 show an example of a battery pack 1. Referring to Fig. 8 and Fig. 9, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 may be covered by the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0127] The present application further provides a power consuming device, the power consuming device including at least one of the secondary battery, the battery module, or the battery pack according to the present application. The secondary battery, the battery module, or the battery pack may be used as a power source for the power consuming device, or may be used as an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0128] The power consumption device can be a secondary battery, a battery module, or a battery pack depending on its usage demand.

[0129] 10 is an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. A battery pack or a battery module can be employed to meet the demand for high power and high energy density of the secondary battery of the power consuming device.

[0130] Another example of the device may be a mobile phone, a tablet computer, a notebook computer, etc. These devices are generally required to be thin and lightweight, and may employ a secondary battery as a power source.

[0131] Working Example The following describes the examples of the present application. The examples described below are illustrative and are used only to interpret the present application, and should not be understood as limitations on the present application. If no specific techniques or conditions are specified in the examples, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. If no manufacturer is specified, the reagents or instruments used are all commercially available products.

[0132] (1) Manufacturing of expansion tapes: Based on the compositions of the expansion tapes of Examples 1 to 28 and Comparative Example 1 in Table 1, materials were selected and prepared for use.

[0133] Manufacturing of expansion layer: The solvent ethyl acetate, adhesive base, hardener, and temperature expansion material are weighed according to the preset composition of the expansion layer. The weighed solvent, adhesive base, and temperature expansion material are then uniformly stirred under vacuum to manufacture a slurry precursor. Next, a hardener is added to the slurry precursor and the mixture is stirred under vacuum for 20 minutes to manufacture an expansion layer slurry, which has a solid content of 50% and a viscosity of 500 mPa·s. The manufactured expansion layer slurry is uniformly applied to the first surface of the substrate to manufacture the expansion layer. The compositional blending ratio of the expansion layer can be seen in Table 1.

[0134] Preparation of undercoat layer: SIS and SEBS materials are put into a glass reactor in a mass ratio of 1:1, heated and uniformly stirred, then coated on the second surface of the PET substrate, rolled up and ready for use. In particular, the preparation of the undercoat layer in Example 13 is performed by heating and stirring an acrylic adhesive (PMMA), uniformly coating on the second surface of the PET substrate, and rolled up and ready for use.

[0135] Preparation of the oriented polystyrene layer: An oriented polystyrene film is transfer coated onto the intumescent layer.

[0136] (2) Manufacturing of electrode assembly: Manufacture of positive electrode plate: The positive electrode active material lithium iron phosphate, the conductive agent conductive carbon black, and the adhesive are mixed and dispersed in N-methylpyrrolidone in a weight ratio of 97:1:2, where the adhesive is modified polyvinylidene fluoride. The resulting mixture is thoroughly stirred and mixed uniformly to form a positive electrode slurry, which is then uniformly applied onto the positive electrode current collector aluminum foil, and then dried, cold pressed, and cut to obtain the positive electrode plate.

[0137] Manufacturing of negative electrode plate: The active material artificial graphite, conductive agent carbon black, adhesive styrene butadiene rubber (SBR), and thickener sodium hydroxymethylcellulose (CMC-Na) are dissolved in the solvent deionized water in a weight ratio of 97:0.4:1.5:1.1, and mixed uniformly to prepare a negative electrode slurry. The negative electrode slurry is uniformly applied to the negative electrode current collector copper foil, and the negative electrode plate is obtained after drying, cold pressing, and cutting.

[0138] Separator: A PE porous polymer film is used as the separator.

[0139] Manufacture of electrode assembly: The positive electrode plate, the separator, and the negative electrode plate are stacked in order, and then wound, pressed to form, and tab-welded to manufacture the electrode assembly.

[0140] (3) Secondary battery manufacturing: Electrolyte: In an argon atmosphere glove box with a water content of <10 ppm, equal volumes of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed to obtain an organic solvent, and then 1 mol / L of LiPF6 is uniformly dissolved in the organic solvent to obtain an electrolyte.

[0141] The undercoat layer of the expansion tape of Examples 1 to 28 and Comparative Example 1 is attached to the surface of the electrode assembly, then placed in a case and vacuum dried at 100°C to cause the expansion tape to undergo primary expansion. The case is sealed by covering the opening of the case with a cover plate. Next, an electrolyte is injected into the sealed case at room temperature, and the expansion tape that has undergone primary expansion is allowed to absorb the electrolyte and undergo secondary expansion. After that, a secondary battery is obtained through processes such as chemical conversion. It should be noted that the width of the gap between the case and the electrode assembly is between 1mm and 2mm, which matches the second expansion thickness of the expansion tape used, and the difference between the width of the gap and the second expansion thickness is within a range of ±50μm.

[0142] Test part: Adhesion Test: The adhesive strength test was carried out according to the tape 180 degree peel strength test method. Specifically, the tape to be measured was cut into a sample of 20*100mm size for use. One side of the undercoat layer of the cut sample was attached to a steel plate, and then rolled back and forth twice with a 2kg press roller to completely bond the sample, and one end of the sample was bent in the opposite direction, with a bending angle of 180°. It was tested using a high-speed steel bar tension machine, one end of the steel plate was fixed to the lower fixture of the tension machine, and the bent end of the sample was fixed to the upper fixture, and the angle of the sample was adjusted to ensure that the upper and lower ends were in a vertical position, and then the sample was pulled at a speed of 50mm / min until the sample was completely peeled off from the steel plate, and the displacement and acting force during the process were recorded, and the force when the force received was generally balanced was considered to be the adhesive strength of the sample.

[0143] Expansion Tape Expansion Test: The expansion tape was cut into 5*5mm sheets, then pasted onto a substrate, and the initial unexpanded thickness was measured with a micrometer. The expansion tape was then kept at 100°C for 4h to undergo primary expansion, and the primary expansion thickness was measured with a micrometer. The primary expanded expansion tape was then immersed in an electrolyte at 45°C for 48h to undergo secondary expansion, and the secondary expansion thickness was measured with a micrometer. The thickness test was as follows: Two PP plates with flat surfaces measuring 5cm*5cm*0.5cm were prepared, the PP plates were placed on a horizontal workbench, and the tape before and after expansion was placed flat between the PP plates, and the thickness was measured with a micrometer, with 10 points measured and the average value taken. The maximum expansion ratio is the ratio of the secondary expansion thickness to its initial unexpanded thickness.

[0144] Compressibility test: A stress of 1.5 MPa was applied to the expansion tape that had undergone secondary expansion, and the thickness when subjected to the force was measured. The ratio of the reduction in thickness of the expansion tape when subjected to the force to its secondary expansion thickness was the compression ratio of the expansion tape.

[0145] Secondary battery cycle test: The manufactured battery cell was subjected to a test cycle, and after the battery cell had been cycled 100 times, the battery cell was removed. The battery cell was then disassembled, and the expansion tape was removed. After that, its thickness was measured with a micrometer, and the area around the adhesive was visually inspected for any colloidal extrusion.

[0146] [Table 1] JPEG2025511583000003.jpg222167JPEG2025511583000004.jpg90167

[0147] [Table 2] JPEG2025511583000006.jpg49167

[0148] [Table 3] JPEG2025511583000008.jpg162169

[0149] As can be seen from the data in Tables 1 to 3, the adhesive strength of the expansion tapes of Examples 1 to 28 is 258N to 470N, the maximum expansion ratio is 3.3 to 10, and the compression ratio of the expansion tape under pressure after expansion is 55% to 72%. The expansion tapes of Examples 1 to 28 have a relatively large expansion ratio and can be compressed under pressure after expansion. Therefore, the expansion tapes of Examples 1 to 28 can better fill the gap between the electrode assembly and the case and better cushion the volume expansion of the electrode assembly during cycling, and meet the demand for low battery margin. The secondary batteries manufactured with the expansion tapes of Examples 1 to 28 do not have adhesive extrusion on the expansion tape within 400 cycles.

[0150] Here, as can be seen from Examples 1 to 8, in Example 4, 031DU40 expandable microspheres are used, and the maximum expansion ratio of the expandable tape produced is relatively large. In Examples 4, 14 to 16, the compositional blending ratio of the expandable layer is adjusted to produce the expandable tape with a maximum expansion ratio of 6.2 to 9.4, which is relatively large. The maximum expansion ratio of the expandable tapes in Examples 1 to 19 and 25 is all ≧5, and if the thickness is 100 μm to 200 μm, it can meet the packaging requirements of most commercially available secondary batteries.

[0151] The difference between the expansion tape of Comparative Example 1 and Example 1 is that the expansion layer does not contain a temperature expansion material, the adhesive strength of the expansion tape is 405 N, and the maximum expansion ratio is 2.1, which is difficult to meet the packaging requirements of commercially available secondary batteries, the compression rate of the expansion tape of Comparative Example 1 after expansion is 51%, and it is actually relatively difficult to manufacture the expansion tape of Comparative Example 1 with a thickness of >100 μm, and its thickness after expansion is difficult to meet the packaging requirements of secondary batteries.

[0152] Each of the technical features of the embodiments described above can be combined in any combination. For the sake of brevity, not all possible combinations of each of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, any combination should be considered within the scope of the present specification.

[0153] The above examples only show some embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the invention patent. It should be noted that those skilled in the art can make some modifications and improvements without departing from the concept of the present application, which all belong to the protection scope of the present application. Therefore, the protection scope of the present application patent shall be subject to the scope of the attached claims. [Explanation of symbols]

[0154] 1, battery pack, 2, upper housing, 3, lower housing, 4, battery module, 5, secondary battery, 51, case, 52, electrode assembly, 53, cover plate, 6, power consumption device, 7, expansion tape, 71, substrate, 72, expansion layer, 73, undercoat layer, 74, oriented styrene layer.

Claims

1. 1. An expanding tape for use in packaging batteries, comprising: a substrate having opposing first and second surfaces; an expansion layer provided on a first surface of the substrate, the expansion layer including an organic adhesive and a temperature expansion material, the temperature expansion material being a material capable of generating a volume expansion through a heat treatment; and an adhesive undercoat layer disposed on the second surface of the substrate.

2. 10. The expansion tape of claim 1, wherein the maximum ratio of the expanded thickness of the expansion tape to its initial unexpanded thickness is ≧5, optionally 5-10.

3. The expansion tape of claim 1 or 2, wherein the initial unexpanded thickness of the expansion tape is between 100 μm and 500 μm, optionally between 150 μm and 300 μm.

4. The expansion tape of any one of claims 1 to 3, wherein the thickness of the expansion tape after expansion is between 1 mm and 5 mm, optionally between 1 mm and 3 mm.

5. The compression ratio of the expansion tape after expansion is 10% to 75%, and the compression ratio refers to the rate at which the thickness of the expansion tape after expansion is reduced by the action of a preset stress. The expansion tape according to any one of claims 1 to 4.

6. the ratio of the thickness of the substrate to the initial unexpanded thickness of the expansion tape is (2-10):100, optionally (3-6):100; Optionally, the thickness of the substrate is from 5 μm to 30 μm, optionally from 5 μm to 15 μm. Optionally, the expandable tape of any one of claims 1 to 5, wherein the thickness of the substrate is from 5 μm to 30 μm, optionally from 5 μm to 15 μm.

7. the ratio of the initial unexpanded thickness of the intumescent layer to the initial unexpanded thickness of the intumescent tape is (75-97):100, optionally (90-97):100; Optionally, the thickness of the intumescent layer is from 75 μm to 450 μm, optionally from 100 μm to 300 μm. Optionally, the intumescent tape of any one of claims 1 to 6.

8. the ratio of the thickness of the undercoat layer to the initial unexpanded thickness of the expansion tape is (1-5):100, optionally (1.5-3):100; Optionally, the undercoat layer has a thickness of from 2.5 μm to 20 μm, optionally from 2.5 μm to 7.5 μm. Optionally, the expandable tape of any one of claims 1 to 7, wherein the thickness of the undercoat layer is from 2.5 μm to 20 μm, optionally from 2.5 μm to 7.5 μm.

9. a mass ratio of the organic adhesive to the temperature expansion material in the expansion layer is (50 to 80):(20 to 50); Optionally, the mass content of the organic adhesive in the expansion layer is 50% to 80%, and the mass content of the temperature expansion material is 20% to 50%. The expansion tape according to any one of claims 1 to 8.

10. The swelling ratio of the organic adhesive is 50% to 200%, and the swelling ratio refers to the ratio of the volume of the organic adhesive when placed in an electrolyte to the volume of the dried organic adhesive. The expansion tape according to any one of claims 1 to 9.

11. The expandable tape according to any one of claims 1 to 10, wherein the organic adhesive has a glass transition temperature of -20°C to 60°C.

12. The expansion tape according to any one of claims 1 to 11, wherein the initial expansion temperature of the temperature expanding material is between 70°C and 130°C, optionally between 80°C and 110°C.

13. 13. The expandable tape of any one of claims 1 to 12, wherein the organic adhesive comprises at least one of an acrylate adhesive, a methyl methacrylate adhesive, an acrylic adhesive, an ethylene-vinyl acetate adhesive, and a polypropylene adhesive, and optionally an acrylate adhesive.

14. 14. The expansion tape of claim 1, wherein the temperature expanding material comprises at least one of expanding microspheres and polyurethane, and optionally comprises expanding microspheres.

15. The expansion tape according to claim 1 , wherein the material of the substrate includes at least one of polyethylene terephthalate, polyimide, polypropylene, and polyethylene.

16. The expandable tape of any one of claims 1 to 15, wherein the undercoat layer comprises at least one of a modified polypropylene, a styrene-isoprene-styrene block copolymer, and a hydrogenated styrene-butadiene-styrene block copolymer.

17. The expansion tape is a layer of oriented polystyrene disposed on a surface of the expandable layer remote from the substrate; Alternatively, the ratio of the thickness of the oriented polystyrene layer to the thickness of the expansion tape is ≦20:100, and optionally (5-20):100; Optionally, the thickness of the oriented polystyrene layer is from 15 μm to 90 μm, and further optionally from 25 μm to 50 μm.

18. A method for producing an expansion tape for use in packaging batteries, comprising the steps of producing an expansion tape according to any one of claims 1 to 17, Producing an intumescent layer on one surface of a substrate; and forming an undercoat layer on a surface of the substrate remote from the intumescent layer.

19. The step of producing the expandable layer comprises: Mixing raw materials of an organic adhesive and a thermal expansion material to prepare a slurry precursor; A step of curing the slurry precursor to produce an expanded layer slurry; applying the intumescent layer slurry to a surface of the substrate.

20. The method for producing the expansion tape includes the steps of: (1) The solid content of the expanded layer slurry is 10% to 50%; (2) The method for producing an expansion tape according to claim 19, wherein the viscosity of the expansion layer slurry is 50 mPa·s to 500 mPa·s.

21. 18. Use of the expanding tape according to any one of claims 1 to 17 in the manufacture of a battery.

22. A method for manufacturing a secondary battery, comprising: applying the undercoat layer of the expandable tape of any one of claims 1 to 17 to a surface of an electrode assembly; placing the electrode assembly with the expansion tape attached thereto in a case and vacuum drying the same at 70°C to 130°C to primarily expand the expansion tape; sealing the case; injecting an electrolyte into the sealed case, and allowing the expansion tape that has undergone primary expansion to absorb the electrolyte and undergo secondary expansion.

23. A secondary battery, A case filled with an electrolyte; an electrode assembly disposed within the case; 18. A secondary battery comprising: the expansion tape according to claim 1 , the expansion tape being disposed between the case and the electrode assembly and filling a gap between the case and the electrode assembly, and the undercoat layer of the expansion tape being attached to a surface of the electrode assembly.

24. A battery module comprising the secondary battery according to claim 23.

25. A battery pack comprising the battery module of claim 24.

26. A power consuming device comprising at least one selected from the group consisting of the secondary battery according to claim 23, the battery module according to claim 24, and the battery pack according to claim 25.

Images