A type of adhesive tape and battery

Abstract

This application belongs to the field of battery manufacturing technology, specifically relating to an adhesive paper and a battery. The adhesive paper includes a substrate layer and a coating layer disposed on at least one surface of the substrate layer; the substrate layer contains a plurality of fibers, which intersect and / or overlap to form pores, and the average diameter of the fibers is 2μm to 20μm; the coating layer is partially embedded in the pores, and based on 100% of the total mass of the coating layer, the coating layer contains 40wt% to 80wt% inorganic particles. The adhesive paper, comprising a substrate layer and a coating layer, with the substrate layer containing a plurality of fibers having an average fiber diameter of 2μm to 20μm, and the coating layer containing inorganic particles, allows the adhesive paper to adsorb a large amount of electrolyte, thereby enabling normal ion shuttle transport, allowing the capacity of the positive and negative electrode active materials to be fully utilized, and improving the battery energy density.

Description

Technical Field

[0001] This application belongs to the field of battery manufacturing technology, specifically relating to an adhesive paper and a battery. Background Technology

[0002] Lithium-ion batteries are widely used in mobile phones, laptops, electric vehicles, and other fields. As market demand continues to expand, new requirements are being placed on the energy density of lithium-ion batteries.

[0003] To improve battery safety, adhesive tape is often attached to the positive and negative electrodes. However, existing adhesive tape does not allow lithium ions to pass through, preventing the area where the tape is attached from utilizing its capacity, thus resulting in a loss of energy density in the lithium-ion battery. Summary of the Invention

[0004] Therefore, the technical problem to be solved by this application is to overcome the defects of existing lithium-ion batteries, such as the adhesive paper on the positive and negative electrode plates not allowing lithium ions to pass through, causing the adhesive paper bonding area to not exert its capacity and the battery energy density to be lost, thereby providing an adhesive paper and a battery.

[0005] Therefore, this application provides the following technical solution.

[0006] This application provides an adhesive paper for batteries, the adhesive paper comprising a substrate layer and a coating layer disposed on at least one surface of the substrate layer; the substrate layer comprises a plurality of fibers, which intersect and / or are stacked to form pores, the average diameter of the fibers being 2 μm to 20 μm; the coating layer is partially embedded in the pores, and the coating layer comprises 40 wt% to 80 wt% inorganic particles based on 100% of the total mass of the coating layer.

[0007] Furthermore, the pore size is 0.1 μm to 50 μm.

[0008] Furthermore, the pore size is 0.5μm to 10μm.

[0009] Furthermore, the average particle size of the inorganic particles is 150 nm to 2 μm; and / or,

[0010] The average diameter of the fiber is 3μm to 6μm.

[0011] Furthermore, the coating layer contains 20wt% to 60wt% adhesive.

[0012] Furthermore, the inorganic particles and / or the adhesive are embedded within the pores; and / or,

[0013] The adhesive comprises at least one of polyisobutylene, styrene-isoprene copolymer, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and styrene-butadiene rubber; and / or,

[0014] The weight-average molecular weight of the adhesive is not less than 15 × 10⁻⁶. 4 ; and / or,

[0015] The inorganic particles include at least one of aluminum oxide, boehmite, LLZO, LLTO, LATP, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zirconium oxide, zinc oxide, calcium oxide, magnesium hydroxide, aluminum hydroxide, barium hydroxide, barium sulfate, calcium silicate, and titanium dioxide.

[0016] Furthermore, the porosity of the adhesive tape is 30%–80%; and / or,

[0017] The liquid retention rate of the adhesive tape is not less than 120%.

[0018] Furthermore, the thickness of the substrate layer is 5 μm to 20 μm; and / or,

[0019] The substrate layer is made of at least one of polyethylene terephthalate, polyethylene, polypropylene, polyimide, polyvinyl chloride, polyethylene, and polypropylene; and / or,

[0020] The thickness of the coating layer is 2μm to 15μm.

[0021] Furthermore, within any 190μm×255μm area range on the coating surface, the number of pores with a diameter greater than 8μm on the coating surface is not less than 10.

[0022] This application provides a battery, the battery including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; at least a portion of at least one surface of the positive electrode, the negative electrode, and the separator is provided with the aforementioned adhesive paper.

[0023] The technical solution of this application has the following advantages:

[0024] 1. The adhesive paper provided in this application includes a substrate layer and a coating layer. The substrate layer contains several fibers with an average fiber diameter of 2μm to 20μm. The coating layer contains inorganic particles. This structure allows the adhesive paper to adsorb a large amount of electrolyte, thereby enabling normal ion shuttle, allowing the capacity of the positive and negative electrode active materials to be properly utilized, and improving the battery energy density. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of the adhesive tape in Embodiment 1 of this application;

[0027] Figure 2 This is an SEM image of the surface of the adhesive tape coating layer in Embodiment 1 of this application;

[0028] Figure 3 SEM image of the surface of the adhesive tape substrate layer in Example 1 of this application;

[0029] Figure 4 It is the coating layer of the adhesive tape obtained after disassembling the battery, observed using a 500X magnifying glass;

[0030] Figure 5 This is a topographic image of the negative electrode sheet corresponding to the adhesive tape position after disassembling the battery in Embodiment 1 of this application;

[0031] Figure 6 This is a topographic image of the negative electrode corresponding to the adhesive tape position after disassembling the battery of Comparative Example 5 of this application;

[0032] Figure label:

[0033] 1-Coating layer; 2-Substrate layer. Detailed Implementation

[0034] The following embodiments are provided to better understand this application and are not limited to the preferred embodiments described herein. They do not constitute a limitation on the content and scope of protection of this application. Any product that is the same as or similar to this application, derived by anyone under the guidance of this application or by combining features of this application with other prior art, falls within the scope of protection of this application.

[0035] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0036] To improve battery safety, existing technologies often use adhesive tape to attach adhesive strips to the positive and negative electrode sheets. This adhesive tape typically consists of a substrate layer and an adhesive layer, and it cannot conduct ions. Consequently, the active material in the adhesive tape-attached area cannot utilize its capacity, resulting in a loss of battery energy density. To address these issues, this application provides the following technical solution.

[0037] In a first aspect, this application provides an adhesive paper for batteries, the adhesive paper comprising a substrate layer and a coating layer disposed on at least one surface of the substrate layer; the substrate layer comprises a plurality of fibers, the plurality of fibers being intersected and / or stacked to form pores, the average diameter of the fibers being 2μm to 20μm; the coating layer is partially embedded in the pores, and the coating layer comprises 40wt% to 80wt% inorganic particles based on 100% of the total mass of the coating layer.

[0038] The adhesive tape of this application can absorb a large amount of electrolyte, ensuring the electrolyte retention rate of the tape and enabling it to conduct ions, thereby increasing the battery energy density. The substrate layer of the adhesive tape contains several cross-laminated fibers that form a three-dimensional network structure, giving the substrate layer porosity and allowing the tape to absorb a large amount of electrolyte, thus increasing the electrolyte retention capacity. Fibers with an average diameter below 2 μm result in smaller pores in the substrate layer, increasing tortuosity and lengthening the lithium-ion transport path, thus affecting the ion transport rate. Furthermore, smaller diameter fibers have lower strength; an average fiber diameter below 2 μm significantly reduces the mechanical strength of the adhesive tape. Additionally, the fibers in the substrate layer tend to be too densely interwoven and stacked, hindering the embedding of the coating layer and reducing the adhesion strength between the coating and substrate layers, as well as lithium-ion permeability. Fibers with an average diameter above 20 μm create larger pores, which, while improving the adhesion strength between the coating and substrate layers, reduces the porosity of the adhesive tape, affecting electrolyte retention and lithium-ion permeability. It also leads to excessive hardness and thickness of the adhesive tape, which is detrimental to adhesive application, battery manufacturing, and improving battery energy density. Furthermore, based on 100% of the total mass of the coating layer, the coating layer contains 40 wt% to 80 wt% inorganic particles, which can absorb a certain amount of electrolyte, increasing the electrolyte retention of the adhesive tape and improving lithium-ion permeability. When the average fiber diameter and the content of inorganic particles simultaneously meet the aforementioned ranges, the amount of coating embedded in the substrate layer can be appropriate, and the fibers can maintain appropriate swelling under electrolyte immersion, thereby improving the bonding force between the coating layer and the substrate layer, thus enhancing the overall electrolyte retention capacity of the adhesive paper. When adhesive paper with a large electrolyte retention capacity is applied to batteries, the adhesive paper can conduct ions, and lithium ions can freely and quickly shuttle in the area where the adhesive paper is pasted, without affecting the capacity of the active material in the area where the adhesive paper is pasted, ensuring that the battery has energy density.

[0039] It should be noted that the average fiber diameter was obtained using methods known in the art. One method is as follows: a sample of adhesive tape is taken, and 10 SEM images are obtained at different locations on the sample under an electron microscope. The diameter of any 80 fibers in each SEM image is measured, and the average value is calculated. The average fiber diameter is then obtained by averaging the data from the 10 SEM images.

[0040] Partial embedding of the coating layer into the pores means that some inorganic particles in the coating layer enter the pores formed by the intersection and / or stacking of several fibers. The coating layer containing 40wt% to 80wt% inorganic particles means that, based on a 100% mass fraction of the coating layer, the coating layer includes 40wt% to 80wt% inorganic particles. Both the coating layer embedded in the pores and the coating layer located on the surface of the substrate layer have an inorganic particle content of 40wt% to 80wt%.

[0041] For example, the average diameter of the fiber is 2μm, 4μm, 6μm, 8μm, 10μm, 12μm, 14μm, 16μm, 18μm, 20μm or within any two of the above values; the mass content of inorganic particles in the coating layer is 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt% or within any two of the above values.

[0042] In one optional embodiment, the pore size is 0.1 μm to 50 μm. Controlling the pore size of the substrate layer in this application allows for an appropriate embedding amount of the coating layer within the substrate layer, further improving the electrolyte retention of the adhesive tape and enabling it to absorb more electrolyte, thereby enhancing lithium-ion transport. Excessively large pores can cause the coating layer to penetrate from one side of the substrate layer to the other, affecting the wafer fabrication process; excessively small pores result in insufficient coating embedding, hindering the bonding between the coating layer and the substrate layer, easily causing ceramic particles in the coating layer to fall and puncture the separator, and excessive tortuosity of the adhesive tape, obstructing the normal ion transport path and affecting lithium-ion transport efficiency. It should be noted that the pore size refers to the pore size with the largest proportion in the pore size distribution diagram. The pore size is obtained using methods known in the art. One example is: taking an adhesive tape sample, immersing it in a benzene solution for 4 hours, removing the sample, drying it, and measuring the pore size using a pore size analyzer. The pore size with the largest proportion in the pore size distribution diagram is taken as the pore size. Note that the adhesive tape can also be impregnated with organic solvents such as toluene; this application does not limit the type of impregnation solvent. For example, the pore size is 0.1 μm, 0.5 μm, 1 μm, 3 μm, 7 μm, 11 μm, 16 μm, 23 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or within any two of the above values.

[0043] In one optional embodiment, the pore size is 0.5μm to 10μm, which allows the fiber to maintain appropriate swelling under the wetting of the electrolyte, improves the bonding force between the coating layer and the substrate layer, and helps to further improve the electrolyte adsorption of the adhesive paper and maintain the integrity of the coating layer.

[0044] In one optional embodiment, the average particle size of the inorganic particles is 150 nm to 2 μm. The particle size of the inorganic particles affects the liquid retention capacity of the inorganic particles and the size and number of pores formed by the stacking of inorganic particles, thereby further affecting the liquid retention capacity of the adhesive paper. This application can further improve the liquid retention capacity of the adhesive paper by adjusting the average particle size of the inorganic particles.

[0045] In one optional embodiment, the average diameter of the fibers is 3μm to 6μm. A smaller average fiber diameter results in higher porosity and greater liquid retention in the substrate. However, an excessively small average fiber diameter creates smaller voids, hindering the bonding between the coating and substrate layers. This can cause ceramic particles in the coating to fall and puncture the separator, increasing tortuosity and lengthening the lithium-ion transport path, thus affecting lithium-ion transport efficiency. An excessively small average fiber diameter also affects mechanical strength and processing performance. Conversely, a large average fiber diameter results in lower porosity, impacting liquid retention and electrical properties. This application further controls the average fiber diameter to 3μm to 6μm to balance the embedding porosity of the coating in the substrate layer and the liquid retention of the substrate, resulting in adhesive paper with optimal liquid retention, lithium-ion permeability, mechanical strength, and processing performance.

[0046] It should be noted that the average particle size of the inorganic particles was obtained using methods known in the art. One method is to measure the diameter of 100 particles randomly on the surface of the adhesive tape coating under SEM, calculate the average value, and then measure 10 times at 10 different locations, taking the average value as the average particle size of the inorganic particles.

[0047] For example, the average particle size of the inorganic particles is 150nm, 300nm, 500nm, 800nm, 1μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm, 2μm, or within any two of the above values.

[0048] In one optional embodiment, the coating layer contains 20wt% to 60wt% adhesive, based on 100% of its total mass. It should also be explained that a portion of the adhesive in the coating layer is embedded in the pores, and / or enters the pores formed by the intersection and / or stacking of several fibers. The method for testing the mass content of inorganic particles in the coating layer is a method known in the art. One example is as follows: a sample of adhesive paper is weighed and recorded as M. It is then soaked in a benzene solution for 4 hours, causing the coating layer to detach from the substrate layer. The substrate layer is removed, dried, and weighed, recorded as M1. The total mass of the coating layer is M-M1. The benzene solution is filtered using filter paper with a mass of M0. The adhesive in the coating layer dissolves in the benzene, and the inorganic particles adhere to the filter paper. After drying the filter paper, it is weighed and recorded as M2. The mass of the inorganic particles is M2-M0. The mass content of inorganic particles in the coating layer is (M2-M0) / (M-M1). Note that the adhesive tape sample can also be impregnated in organic solvents such as toluene. This application does not limit the type of impregnation solvent, as long as it can separate the coating layer from the substrate. Furthermore, the mass content of the adhesive in the coating layer is calculated using the following formula: Adhesive mass content = 1 - Inorganic particle mass content. For example, the mass content of the adhesive in the coating layer is 20wt%, 24wt%, 28wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, or within any two of the above values.

[0049] In one optional embodiment, the inorganic particles and / or the adhesive are embedded within the pores; and / or,

[0050] The adhesive comprises at least one of polyisobutylene, styrene-isoprene copolymer, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and styrene-butadiene rubber; and / or,

[0051] The adhesive has a weight-average molecular weight of not less than 1.5 × 10⁻⁶. 5 ; and / or,

[0052] The inorganic particles include at least one of aluminum oxide, boehmite, LLZO, LLTO, LATP, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zirconium oxide, zinc oxide, calcium oxide, magnesium hydroxide, aluminum hydroxide, barium hydroxide, barium sulfate, calcium silicate, and titanium dioxide.

[0053] It should be noted that the weight-average molecular weight of the adhesive was obtained using methods known in the art. For example, gel permeation chromatography. For example, the weight-average molecular weight of the adhesive is 1.5 × 10⁻⁶.5 1.8×10 5 1.3×10 6 And so on, which will not be listed and explained here.

[0054] Existing adhesive tapes lack pores in their substrate layer, preventing electrolyte absorption and ion conduction. This results in the active material in the adhesive area not being able to perform at its full capacity. The adhesive tape described in this application has fiber-formed pores in its substrate layer that can absorb some electrolyte. Furthermore, the inorganic particles in the coating layer, as well as the pores formed by their stacking, can absorb a certain amount of electrolyte, allowing ions to penetrate the tape through the electrolyte. Therefore, the active material in the tape-covered area can perform at its full capacity, ensuring the battery's energy density. This application embeds inorganic particles and / or adhesives within the pores to increase the electrolyte retention capacity of the adhesive tape, thereby enabling ion conduction and allowing the active material in the tape-covered area to perform at its full capacity, ensuring the battery's energy density.

[0055] It should be explained that inorganic particles and / or adhesives are embedded in the pores of the substrate layer, and the size of the pores determines the amount of inorganic particles and adhesives embedded.

[0056] In one optional embodiment, the porosity of the adhesive tape is 30% to 80%, and the porosity of the adhesive tape in this application is 30% to 80%, which helps to improve the liquid retention capacity of the adhesive tape.

[0057] In one optional embodiment, the liquid retention rate of the adhesive tape is not less than 120%.

[0058] For example, the porosity of the adhesive tape is 30%, 40%, 50%, 60%, 70%, 80%, or within any two of the above values. The liquid retention rate of the adhesive tape is 120%, 130%, 140%, 150%, 160%, 170%, or within any two of the above values.

[0059] It should be noted that the particle size of inorganic particles and the average diameter of fibers can be obtained by conventional testing methods, including but not limited to SEM images.

[0060] The porosity of the adhesive tape was obtained according to conventional methods in the art. One gravimetric method for determining the porosity of adhesive tape is described here: a sample of adhesive tape is weighed, immersed in a n-butanol solution for 2 hours, removed, the surface liquid is wiped off, and then weighed. The porosity is calculated using the following formula:

[0061]

[0062] Where W2 is the weight of the adhesive paper sample after soaking in n-butanol, in g; W1 is the weight of the adhesive paper before soaking, in g; and A is the area of ​​the adhesive paper sample, in cm². 2; d is the average thickness of the adhesive paper sample, in cm; ρ is the density of n-butanol, 0.811 g / mL.

[0063] The electrolyte retention rate of the adhesive tape was tested using conventional methods in the art. One method is described here, which includes: removing the adhesive tape from the battery, baking it, weighing it (recorded as m1), immersing the tape in the electrolyte for a period of time, removing the tape, drying its surface, weighing it (recorded as m2), and calculating the electrolyte retention rate using the following formula:

[0064]

[0065] In one optional embodiment, the thickness of the substrate layer is 5 μm to 20 μm; and / or,

[0066] The thickness of the coating layer is 2μm to 15μm; and / or,

[0067] The substrate layer is made of at least one of polyethylene terephthalate, polyethylene, polypropylene, polyimide, polyvinyl chloride, polyethylene, and polypropylene.

[0068] For example, the thickness of the substrate layer is 5 μm, 8 μm, 13 μm, 15 μm, 18 μm, 20 μm, or within any two of the above values. The thickness of the coating layer is 2 μm, 5 μm, 8 μm, 13 μm, 15 μm, or within any two of the above values.

[0069] It should be noted that the substrate layer also includes inorganic particles embedded in the pores and an adhesive; the thickness of the coating layer refers to the thickness located on the surface of the substrate layer.

[0070] In one optional embodiment, an area of ​​190μm × 255μm is randomly selected on the coating surface. The number of pores with a diameter greater than 8μm on the coating surface is no less than 10, which can further improve liquid retention and ion transport effects. Here, "pore diameter" refers to the diameter of a single pore. A pore with a diameter greater than 8μm on the coating surface means a pore with a diameter ≥ 8μm. It should be noted that the number of pores with a diameter greater than 8μm on the coating surface can be obtained through SEM testing. For example, it can be tested as follows: Using a scanning electron microscope, an area of ​​190μm × 255μm is randomly selected on the coating surface. The surface of the ceramic layer is observed at 5000x magnification. The diameter of the observed pores is measured on the obtained image. Two points with the largest distance are randomly selected at the edge of the pore. When the measured distance is greater than 8μm, the pore diameter is considered to be greater than 8μm. The number of pores with a diameter greater than 8μm within the area is then calculated.

[0071] Secondly, this application also provides a battery, the battery including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; at least one of the positive electrode, the negative electrode, and the separator has the aforementioned adhesive paper disposed at a portion of its surface.

[0072] It should be noted that the positive electrode, negative electrode, and separator all have two surfaces, and the adhesive tape is disposed on at least a portion of at least one of these surfaces. Note that "partial" includes cases where the adhesive tape covers part or all of the surface.

[0073] Optionally, the adhesive tape is disposed on at least a portion of at least one surface of the positive electrode sheet; and / or,

[0074] The aforementioned adhesive paper is disposed on at least a portion of at least one surface of the negative electrode sheet; and / or,

[0075] The adhesive tape is disposed on at least a portion of at least one surface of the diaphragm.

[0076] The battery of this application has adhesive tape disposed on at least one surface of the positive electrode, negative electrode, and separator. Because the adhesive tape has a high electrolyte retention capacity and can conduct ions, lithium ions can freely and quickly shuttle through the area where the adhesive tape is attached, without affecting the capacity utilization of the active material in the area where the adhesive tape is attached. This ensures that the battery has a high energy density and overcomes the shortcomings of existing technologies where lithium ions cannot shuttle through the area where the adhesive tape is attached and the capacity of the active material in that area cannot be fully utilized.

[0077] In one optional embodiment, the positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one side of the positive current collector; the positive active material layer is bonded to the adhesive tape, and the bonding force of the bonding is not higher than 3N / mm.

[0078] In one optional embodiment, the positive electrode active material layer comprises a positive electrode active material, which is a common raw material in the art, such as at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide (LiCoO2), lithium manganese oxide, lithium manganese iron phosphate, or lithium titanate. The positive electrode active material layer also comprises additives, such as binders and conductive agents, which are common raw materials in the art. Conductive agents include at least one of conductive carbon black and carbon nanotubes; binders include at least one of PVDF, HSV, PTFE, SBR, and PAA. The positive electrode current collector is a common current collector in the art, such as aluminum foil or titanium foil.

[0079] In one optional embodiment, the negative electrode sheet includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector; the negative current collector can be a common current collector in the art, such as copper foil, nickel foil, iron-nickel alloy foil, or copper-nickel alloy foil. The negative active material layer comprises an active material, which is a common raw material in the art, such as at least one of carbon-based materials, silicon-based materials, tin-based materials, or titanium-based materials; specifically including at least one of artificial graphite, natural graphite, soft carbon, hard carbon, elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, silicon alloys, elemental tin, tin oxide compounds, tin alloys, elemental titanium, titanium oxide compounds, or titanium alloys. It is understood that the composition of the negative active material layer may also include additives, such as conductive agents and binders. Conductive agents include at least one of carbon black and carbon nanotubes, and the content of conductive agents in the negative active material layer is not higher than 3 wt%. Binders include at least one of SBR binders and PAA binders, and the content of binders in the negative active material layer is not higher than 3 wt%. The active material, conductive agent, and binder in the negative electrode active material layer are mixed in the conventional proportions used in this field.

[0080] In one optional embodiment, the diaphragm includes a base membrane and a coating on at least one surface of the base membrane, the coating including at least one layer structure selected from ceramic and adhesive layers. The material of the base membrane is selected from materials known in the art and is not limited thereto; as an example, the material of the base membrane includes at least one selected from polyethylene, polypropylene, polyethylene terephthalate, polyphenylene sulfide, polyimide, polystyrene, polytetrafluoroethylene, polymethyl methacrylate, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, cellulose, etc. The ceramic layer comprises inorganic particles and a binder, optionally with a mass ratio of (40-95):(5-60); the inorganic particles include at least one of boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon dioxide, tin oxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, cerium dioxide, zirconium titanate, barium titanate, and magnesium fluoride; the binder includes at least one of polyvinylidene fluoride, a copolymer of polyvinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polytetrafluoroethylene, and polyhexafluoropropylene. The coating layer is a polymer coating; the polymer is a compound commonly used in the art; for example, the polymer includes copolymers or homopolymers formed from at least one monomer selected from acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, ethylhexyl acrylate, styrene, α-methylstyrene, vinyltoluene, ethylene, vinyl acetate, acrylonitrile, vinylidene fluoride, hexafluoropropylene, and chlorophthalic anhydride; the polymer may also be at least one selected from polyetherimide, polyamideimide, polyimide, and vinylidene fluoride-hexafluoropropylene copolymer.

[0081] In one optional embodiment, the battery further includes an electrolyte comprising an electrolyte salt and a solvent. It is understood that the electrolyte is a common raw material used in the art for battery fabrication. The electrolyte salt includes at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP). The solvent includes at least one selected from fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE). The electrolyte also includes additives, the type and amount of which are determined according to requirements.

[0082] In one alternative embodiment, the battery is manufactured according to methods known in the art. One method described herein includes stacking a positive electrode, a separator, and a negative electrode, and then winding them to obtain the battery.

[0083] Example 1

[0084] This embodiment provides a battery, including:

[0085] Positive electrode sheet: See the structural diagram of the adhesive paper. Figure 1 The adhesive tape includes a substrate layer 2 and a coating layer 1 disposed on one side of the adhesive tape. The substrate layer is made of polyethylene terephthalate and has a thickness of 10 μm. The substrate layer includes several fibers with an average diameter of 3 μm and pores with a diameter of 4.5 μm formed between the fibers. The coating layer includes boehmite particles and styrene-isoprene copolymer adhesive (with a molecular weight of 250,000) in a mass ratio of 1:1. The inorganic particles have an average particle size of 0.9 μm, and the coating layer has a thickness of 6 μm. The porosity of the adhesive tape is 40%, and the liquid retention rate is 150%. Figure 2 This is an SEM image of the adhesive coating layer surface. The image shows that inorganic particles and adhesive are distributed on the surface. Figure 3This is an SEM image of the adhesive tape substrate layer. As can be seen from the image, the substrate layer contains several fibers, which form a network structure.

[0086] Lithium cobalt oxide (CCO), PVDF binder, and conductive carbon black were dispersed in N-methylpyrrolidone at a mass ratio of 97:2:1 to obtain a uniform CCO slurry. This slurry was then uniformly coated onto both surfaces of an 8 μm thick aluminum foil. After drying and rolling, an electrode sheet with a thickness of 78 μm was obtained. The electrode sheet was then slit and welded with positive electrode tabs to obtain the positive electrode sheet. The adhesive used for finishing the positive electrode sheet was the adhesive paper described in this application.

[0087] Negative electrode sheet: Graphite, styrene-butadiene rubber (SBR) binder, sodium carboxymethyl cellulose (CMC) thickener, and conductive carbon black (CCH) conductive agent are mixed and dispersed in deionized water at a mass ratio of 97:1:1.5:0.5 to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of a 6 μm thick copper foil. After coating, the foil is dried and rolled to obtain an electrode sheet with a thickness of 98 μm. The negative electrode sheet is then obtained by slitting and welding negative electrode tabs.

[0088] Electrolyte: includes solvent and lithium salt. The solvent consists of diethyl carbonate, dimethyl carbonate and ethylene carbonate in a volume ratio of 1:1:1. The lithium salt is LiPF6 with a concentration of 1 mol / L.

[0089] The positive electrode, separator, and negative electrode are stacked in sequence, wound into a core, and encapsulated with aluminum-plastic film. The core is then baked in a vacuum for 24 hours to remove moisture, and electrolyte is injected. The battery is then formed, aged, vacuum sealed, and sorted to obtain a soft-pack lithium-ion battery.

[0090] After fully charging the lithium-ion battery, disassemble it and observe the number of pores on the surface of the adhesive tape coating. Figure 4 The image shows the coating layer of the adhesive tape obtained after battery disassembly, observed using a 500X magnifying glass. With an area of ​​190μm × 255μm, it contains 12 pores with a surface diameter greater than 8μm. The morphology of the negative electrode corresponding to the adhesive tape location is as follows. Figure 5 As shown, Figure 5 The negative electrode sheet at the adhesive tape coverage area in this embodiment is golden yellow with lithium ions embedded, verifying that lithium ions can shuttle normally at the adhesive tape coverage area, indicating that the active material at the adhesive tape coverage area of ​​this invention can perform its capacity normally.

[0091] Example 2-21

[0092] Examples 2-21 each provide a battery that is basically the same as that in Example 1, except that the adhesive tape is different. The parameters of the adhesive tape are shown in Table 1.

[0093] Comparative Examples 1-4

[0094] Comparative Examples 1-4 each provide a battery that is basically the same as Example 1, except that the adhesive tape is different. The parameters of the adhesive tape are shown in Table 1.

[0095] Comparative Example 5

[0096] Comparative Example 5 provides a battery that is essentially the same as that of Example 1, except that rubber adhesive tape is used instead of the adhesive tape in Example 1. After fully charging this comparative example battery, it is disassembled, and the morphology of the negative electrode corresponding to the adhesive tape location is as follows. Figure 6 As shown, Figure 6 The negative electrode where the adhesive tape covers is black and there are no lithium ions embedded. This means that lithium ions from the positive electrode cannot pass through the adhesive tape to the negative electrode, and the active material in the area covered by the adhesive tape cannot perform its normal capacity.

[0097] Test case

[0098] This test case provides the performance test results for each embodiment and comparative battery, as follows:

[0099] Test method for the liquid retention rate of adhesive tape: Remove the adhesive tape from the battery and bake it in an oven at 60°C for 4 hours. After constant weight, weigh it and record the weight as m1. At room temperature, soak the adhesive tape in electrolyte (same as in Example 1) for 8 hours. After constant weight, weigh it and record the weight as m2. Calculate the liquid retention rate of the adhesive tape according to the following formula.

[0100]

[0101] Battery cycle life: ① At 25℃, charge at a constant current of 0.5C to 4.5V, then charge at a constant voltage to 0.05V (cutoff); ② Discharge at a constant current of 0.5C to 3.0V (cutoff), and record the first discharge capacity as the initial capacity Q1; ③ Repeat steps ①-②, and the resulting discharge capacity is taken as the battery capacity Q2. Calculate the capacity retention rate (%) according to the following formula. When the capacity retention rate decays to 80%, the test is stopped, and the number of cycles at this point is recorded, which is the battery cycle life.

[0102]

[0103] Battery energy density: The battery was fully charged at 0.2C at 25℃ and allowed to stand for 10 minutes. It was then discharged at 0.2C to 3.0V, and the battery capacity was measured. The battery energy density was calculated using the following formula.

[0104]

[0105] Processing Performance: Observe whether abnormalities such as tape breakage or adhesive seepage occur during the process of applying the adhesive tape to the electrode sheet, thus characterizing the processing performance of the adhesive tape. Cracks indicate that cracks appear during the adhesive tape application process, but tape breakage does not occur. Wrinkling indicates that wrinkles or wavy patterns appear during the adhesive tape application process. Adhesive seepage indicates that the coating layer on one side of the adhesive tape substrate layer seeps to the other side during the adhesive tape application process, causing the other side to become sticky and adhere to other parts of the electrode sheet or other electrodes during film winding, affecting the process. Tape breakage indicates that the adhesive tape breaks during the film manufacturing process.

[0106] The cycle life and energy density of the batteries in each embodiment and comparative example are shown in Table 2.

[0107] Table 1. Parameters of battery adhesive paper for each embodiment and comparative example.

[0108]

[0109] Note: " / " in the table indicates that the value does not exist.

[0110] Table 2 Battery performance results for each embodiment and comparative example.

[0111]

[0112]

[0113] Note: " / " in the table indicates that the value does not exist and battery performance cannot be tested. Slight cracks indicate an occasional crack during the manufacturing process, which does not affect the process or adhesive tape application. Slight wrinkles indicate minor wrinkling of the adhesive tape, which does not affect the process or adhesive tape application.

[0114] The results above show that when the adhesive tape provided in this application is used in batteries, it can improve the energy density and cycle life of the batteries, and the active material in the area covered by the adhesive tape can exert its capacity. Examples 1-4 show that controlling the average diameter of the fibers in this application is beneficial for further improving the energy density of the batteries and the mechanical strength of the adhesive tape. Examples 9-17 show that controlling the pore size of the pores formed by the fibers in the substrate layer in this application is beneficial for improving cycle performance and the processing performance of the adhesive tape during the sheet fabrication process.

[0115] As can be seen from Comparative Examples 1-5, compared with the rubber adhesive tape commonly used in the art, the adhesive tape provided in this application can significantly improve energy density and cycle performance.

[0116] If the average diameter of the fibers in the adhesive tape substrate layer is too small, it affects the mechanical strength of the adhesive tape, leading to frequent tape breaks during the sheet manufacturing process and severely impacting the manufacturing process. If the average diameter of the fibers is too large, it causes a significant decrease in the energy density and cycle performance of the battery.

[0117] The content of inorganic particles in the coating layer also affects the performance of the battery and adhesive tape. When the content of inorganic particles in the coating layer is high, the adhesive tape has poor adhesion, and wrinkling and delamination occur during sheet preparation, making it impossible to produce a battery. When the content of inorganic particles in the coating layer is low, it seriously affects the cycle life of the battery.

[0118] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An adhesive tape for batteries, characterized in that, The adhesive tape includes a substrate layer and a coating layer disposed on at least one surface of the substrate layer; the substrate layer contains a plurality of fibers, which intersect and / or are stacked to form pores, and the average diameter of the fibers is 2μm to 20μm; the coating layer is partially embedded in the pores, and the coating layer contains 40wt% to 80wt% inorganic particles based on 100% of the total mass of the coating layer.

2. The adhesive tape according to claim 1, characterized in that, The pore size is 0.1 μm to 50 μm.

3. The adhesive tape according to claim 2, characterized in that, The pore size is 0.5μm to 10μm.

4. The adhesive tape according to claim 1, characterized in that, The inorganic particles have an average particle size of 150 nm to 2 μm; and / or, The average diameter of the fiber is 3μm to 6μm.

5. The adhesive tape according to claim 1, characterized in that, The coating contains 20 wt% to 60 wt% adhesive.

6. The adhesive tape according to claim 5, characterized in that, The inorganic particles and / or the adhesive are embedded within the pores; and / or The adhesive comprises at least one of polyisobutylene, styrene-isoprene copolymer, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and styrene-butadiene rubber; and / or, The adhesive has a weight-average molecular weight of not less than 1.5 × 10⁻⁶. 5 ; and / or, The inorganic particles include at least one of aluminum oxide, boehmite, LLZO, LLTO, LATP, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zirconium oxide, zinc oxide, calcium oxide, magnesium hydroxide, aluminum hydroxide, barium hydroxide, barium sulfate, calcium silicate, and titanium dioxide.

7. The adhesive tape according to claim 1, characterized in that, The porosity of the adhesive tape is 30% to 80%; and / or, The liquid retention rate of the adhesive tape is not less than 120%.

8. The adhesive tape according to claim 1, characterized in that, The thickness of the substrate layer is 5μm to 20μm; and / or, The substrate layer is made of at least one of polyethylene terephthalate, polyethylene, polypropylene, polyimide, polyvinyl chloride, polyethylene, and polypropylene; and / or, The thickness of the coating layer is 2μm to 15μm.

9. The adhesive tape according to claim 1, characterized in that, Take any area of ​​190μm×255μm on the coating surface, and the number of pores with a diameter greater than 8μm on the coating surface shall not be less than 10.

10. A battery, characterized in that, The battery includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; at least a portion of at least one surface of the positive electrode, the negative electrode, and the separator is provided with the adhesive tape as described in any one of claims 1 to 9.

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