Modified conductive carbon material, and preparation method therefor and use thereof

Abstract

The present application provides a modified conductive carbon material, and a preparation method therefor and a use thereof. The modified conductive carbon material is prepared from the following raw materials in parts by weight: 60-80 parts of methyl methacrylate, 10-20 parts of butyl acrylate, 1-5 parts of a polymerizable silane coupling agent, 5-10 parts of a conductive carbon material, 0.1-0.2 parts of a first initiator, 0.1-0.3 parts of a second initiator, 1-10 parts of a first solvent and 0.1-1 part of a second solvent. A methyl methacrylate-butyl acrylate-polymerizable silane coupling agent copolymer is used to carry out surface modification on the conductive carbon material, and physical action and chemical bonding are carried out on the conductive carbon material by means of a polar bond, thereby reducing the surface free energy of carbon material powder, increasing the affinity with styrene-butadiene rubber latex, enabling the styrene-butadiene rubber latex tend to be stable in a slurry, solving the problem of coating film surface stripes caused by instability of the styrene-butadiene rubber latex in the slurry, and enhancing water resistance.

Description

A modified conductive carbon material and its preparation method and application

[0001] This application claims priority to the Chinese patent application number 202310734620.7 filed with the China Patent Office on June 20, 2023. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the technical field of lithium-ion batteries, and specifically relates to a modified conductive carbon material and a preparation method and application thereof. Background Art

[0003] During the manufacturing process of lithium-ion batteries and sodium-ion batteries, in order to improve the current collection intensity of the current collector for the active material and the adhesion performance of the active material to the electrode, a layer of conductive material is first coated on the surface of the current collector, and then the active material is directly coated on the surface of the current collector with conductive material when manufacturing the electrode.

[0004] CN111430723A provides a lithium-supplementing current collector and its preparation method, application, negative electrode plate and lithium-ion battery, wherein the lithium-supplementing current collector includes a current collector body and a lithium-supplementing material layer; the current collector body includes a first carbon coating layer, a base layer and a second carbon coating layer arranged in sequence, and the first carbon coating layer, the base layer and the second carbon coating layer are tightly attached and fixedly connected to each other; the first carbon coating layer is provided with a plurality of through holes at intervals, and the plurality of through holes penetrate the base layer and the second carbon coating layer; the lithium-supplementing material layer is filled in the plurality of through holes. The disclosed lithium-supplementing current collector contains a lithium-supplementing substance, which can achieve precise lithium replenishment of the silicon-carbon negative electrode while reducing the internal resistance of the electrode plate after lithium replenishment, thereby improving the rate performance and cycle performance of the battery, but its water resistance is poor and its application range is limited.

[0005] CN110034302A discloses an ultra-thin carbon-coated current collector and its preparation method, comprising the following steps: cleaning the current collector and then subjecting it to a positive charge treatment to obtain a current collector with a positive surface charge; dissolving a binder, sequentially adding an anionic surfactant and a conductive agent, and stirring to form a negatively charged aqueous conductive slurry; ultrasonically atomizing the negatively charged aqueous conductive slurry into an aerosol, electrostatically depositing it onto the positively charged current collector, and then drying to obtain an ultra-thin carbon-coated current collector. The current collector prepared by this method has a thin and uniform conductive coating, strong adhesion, and good electrical conductivity, but its water resistance is poor, limiting its scope of application.

[0006] In response to environmental concerns, lithium-ion secondary batteries are shifting from oil-based cathode active material coatings to aqueous systems. In the more recently developed aqueous secondary batteries, sodium-ion batteries, both the positive and negative electrode active material coatings are aqueous. This requires the current collector coating to possess strong water resistance.

[0007] CN113140706A relates to the technical field of battery production processes and provides a battery carbonization process and a method for preparing a lithium-ion battery. The battery carbonization process comprises the following steps: S1. Preparing a carbonization slurry comprising 10%-20% by mass of conductive carbon black, 70%-80% by mass of deionized water, 5%-10% by mass of styrene-butadiene rubber (SBR), and 2%-4% by mass of a dispersant; S2. Spraying the carbonization slurry onto the inner surface of a small cylindrical steel or aluminum shell of a lithium-ion battery. The lithium-ion battery preparation method involves carbonizing the inner surface of the small cylindrical steel or aluminum shell to improve the electronic conductivity of the current collector and active material in the steel or aluminum shell, thereby reducing the internal resistance of the lithium-ion battery, increasing the capacity of the lithium-ion battery, and thereby increasing the internal space utilization of the lithium-ion battery. However, due to the poor compatibility of SBR with the conductive agent, blueing is easily observed, resulting in uneven coating of the coating roller.

[0008] SBR for lithium batteries is a styrene-butadiene rubber latex, a water-based binder. It is produced by emulsion copolymerization of styrene and butadiene monomers in water with the addition of emulsifiers and initiators. It forms an aqueous emulsion with a solids content of approximately 50% and exhibits strong water resistance. However, when using SBR as a binder to formulate the current collector carbon coating slurry, SBR has poor affinity with the conductive agent. This makes it unstable in the slurry, resulting in a bluing phenomenon. This can lead to uneven material distribution on the coating roller, resulting in varying shades of streaks on the carbon coating.

[0009] Because SBR in related art is unstable in slurry and exhibits blue tinting, and carbon-coated current collectors suffer from poor water resistance and prone to streaking, developing a conductive carbon material with high affinity for styrene-butadiene rubber latex to produce carbon-coated current collectors with good water resistance and low streaking properties is an urgent problem to be solved in this field.

[0010] Summary of the Invention

[0011] The purpose of the present application is to provide a modified conductive carbon material, a preparation method and an application thereof. The modified conductive carbon material is obtained by polymerizing methyl methacrylate, butyl acrylate and a polymerizable silane coupling agent to obtain a ternary copolymer, and the conductive carbon material is surface modified. The polar bonds of the ternary copolymer cause physical action and chemical bonding on the conductive carbon material, so that SBR tends to be stable in the slurry, reducing the generation of stripes in the carbon-coated current collector and increasing water resistance.

[0012] To achieve this goal, this application adopts the following technical solutions:

[0013] In a first aspect, an embodiment of the present application provides a modified conductive carbon material, wherein the raw materials for preparing the modified conductive carbon material include, in parts by weight: 60-80 parts of methyl methacrylate, 10-20 parts of butyl acrylate, 1-5 parts of a polymerizable silane coupling agent, 5-10 parts of a conductive carbon material, 0.1-0.2 parts of a first initiator, 0.1-0.3 parts of a second initiator, 1-10 parts of a first solvent, and 0.1-1 parts of a second solvent.

[0014] In the modified conductive carbon material provided in the embodiments of the present application, methyl methacrylate, butyl acrylate and a polymerizable silane coupling agent react to form a macromolecular terpolymer; the surface of the conductive carbon material is modified by using a macromolecular surface treatment agent methyl methacrylate (MMA)-butyl acrylate (BA)-polymerizable silane coupling agent terpolymer, and the polar bonds of the terpolymer are used to physically act and chemically bond to the conductive carbon material, thereby reducing the surface free energy of the carbon material powder, alleviating agglomeration, greatly reducing the particle size, significantly weakening the hydrophobicity, increasing the affinity with SBR, improving the degree of crosslinking with SBR, and making the SBR tend to be stable in the slurry.

[0015] In one embodiment, the weight portion of the methyl methacrylate is 60-80 parts, for example, it can be 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0016] In one embodiment, the weight portion of the butyl acrylate is 10-20 parts, for example, it can be 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, this application no longer exhaustively lists the specific points included in the range.

[0017] In one embodiment, the weight portion of the polymerizable silane coupling agent is 1-5 parts, for example, it can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, and specific values ​​between the above points. Due to space limitations and for the sake of simplicity, this application no longer exhaustively lists the specific points included in the range.

[0018] In one embodiment, the weight proportion of the conductive carbon material is 5-10 parts, for example, it can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, and specific point values ​​between the above point values. Due to limited space and for the sake of simplicity, this application no longer exhaustively lists the specific point values ​​included in the said range.

[0019] In one embodiment, the weight portion of the first initiator is 0.1-0.2 parts, for example, it can be 0.1 parts, 0.15 parts, 0.2 parts, and specific values ​​between the above points. Due to space limitations and for the sake of simplicity, this application no longer exhaustively lists the specific points included in the range.

[0020] In one embodiment, the weight portion of the second initiator is 0.1-0.3 parts, for example, it can be 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, and specific values ​​between the above points. Due to space limitations and for the sake of simplicity, this application no longer exhaustively lists the specific points included in the range.

[0021] In one embodiment, the weight portion of the first solvent is 1-10 parts, for example, it can be 1 part, 3 parts, 5 parts, 7 parts, 9 parts, 10 parts, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, this application no longer exhaustively lists the specific point values ​​included in the range.

[0022] In one embodiment, the weight portion of the second solvent is 0.1-1 part, for example, it can be 0.1 part, 0.5 part, 1 part, and specific values ​​between the above points. Due to space limitations and for the sake of simplicity, this application no longer exhaustively lists the specific points included in the range.

[0023] In one embodiment, the polymerizable silane coupling agent includes any one or a combination of at least two of γ-methacryloxypropyltrimethoxysilane (eg, KH-570), vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(methoxyethoxy)silane, or aminopropyltriethoxysilane.

[0024] In one embodiment, the conductive carbon material includes any one of conductive carbon black, conductive graphite, carbon nanotubes, carbon nanofibers, or graphene, or a combination of at least two thereof.

[0025] In one embodiment, the first initiator comprises benzoyl peroxide.

[0026] In one embodiment, the second initiator comprises cumene peroxide.

[0027] In one embodiment, the first solvent comprises toluene.

[0028] In one embodiment, the first solvent is an aqueous solution of toluene.

[0029] In one embodiment, the concentration of toluene in the aqueous solution of toluene is 0.05-0.1 mg / L, for example, it can be 0.05 mg / L, 0.06 mg / L, 0.07 mg / L, 0.08 mg / L, 0.09 mg / L, 0.1 mg / L, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, this application no longer exhaustively lists the specific point values ​​included in the range.

[0030] In one embodiment, the second solvent comprises acetone.

[0031] This application uses a macromolecular surface treatment agent methyl methacrylate (MMA)-butyl acrylate (BA)-silane coupling agent terpolymer to modify the surface of the conductive carbon material. The polar bonds of the terpolymer cause physical action and chemical bonding on the conductive carbon material, thereby reducing the surface free energy of the carbon material powder, alleviating agglomeration, greatly reducing the particle size, and significantly weakening the hydrophobicity. By modifying the hydroxyl and carboxyl groups and double bond cross-linking reactions in SBR, the affinity with SBR is increased, the degree of cross-linking with SBR is improved, and the SBR is stabilized in the slurry.

[0032] In a second aspect, an embodiment of the present application provides a method for preparing the modified conductive carbon material as described in the first aspect, the preparation method comprising:

[0033] Methyl methacrylate, butyl acrylate, a silane coupling agent, a conductive carbon material, a first initiator, a second initiator, a first solvent, and a second solvent are mixed and reacted to obtain the modified conductive carbon material.

[0034] In one embodiment, the preparation method specifically includes: mixing methyl methacrylate, butyl acrylate, a silane coupling agent, and a first solvent, adding a first initiator, keeping warm for a first time, adding a second initiator, keeping warm for a second time, and cooling to obtain a ternary copolymer solution; mixing the ternary copolymer solution with a conductive carbon material and a second solvent, reacting to obtain the modified conductive carbon material.

[0035] In one embodiment, the temperature of the first insulation is 80-90°C, for example, it can be 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, and specific point values ​​between the above point values. Due to limited space and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0036] In one embodiment, the first insulation time is 1-3h, for example, it can be 1h, 1.5h, 2h, 2.5h, 3h, and specific point values ​​between the above point values. Due to limited space and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0037] In one embodiment, the temperature of the second insulation is 110-120°C, for example, it can be 110°C, 112°C, 114°C, 116°C, 118°C, 120°C, and specific point values ​​between the above point values. Due to limited space and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0038] In one embodiment, the second insulation time is 1-3h, for example, it can be 1h, 1.5h, 2h, 2.5h, 3h, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0039] In one embodiment, the reaction temperature is 70-90°C, for example, it can be 70°C, 75°C, 80°C, 85°C, 90°C, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0040] In one embodiment, the reaction time is 2-4 hours, for example, it can be 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0041] In one embodiment, the reaction further includes cooling and drying.

[0042] In one embodiment, the drying temperature is 40-60°C, for example, it can be 40°C, 45°C, 50°C, 55°C, 60°C, and specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific points included in the range.

[0043] In one embodiment, the drying time is 10-15 hours, for example, it can be 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0044] In a third aspect, an embodiment of the present application provides a water-resistant carbon-coated current collector, which includes a foil and a conductive coating arranged on the surface of the foil; the conductive coating includes a combination of the modified conductive carbon material and a binder as described in the first aspect.

[0045] In one embodiment, the conductive coating is formed by coating and curing a modified conductive paste.

[0046] In one embodiment, the solid content of the modified conductive paste is 8-13.5%, and the pH of the modified conductive paste is 6-8.

[0047] In one embodiment, the conductive coating comprises, by weight, 5-10 parts of the modified conductive carbon material and 7-22 parts of a binder.

[0048] In one embodiment, the weight proportion of the modified conductive carbon material is 5-10 parts, for example, it can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, and specific point values ​​between the above point values. Due to limited space and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0049] In one embodiment, the weight proportion of the binder is 7-22 parts, for example, it can be 7 parts, 10 parts, 15 parts, 20 parts, 22 parts, and specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific points included in the range.

[0050] In one embodiment, the binder includes styrene-butadiene rubber latex.

[0051] In one embodiment, the solid content of the styrene-butadiene rubber latex is 40-50%, for example, it can be 40%, 42%, 44%, 46%, 48%, 50%, and specific point values ​​between the above point values. Due to limited space and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0052] In one embodiment, the viscosity of the adhesive is 5-500 mPa.s, for example, it can be 5 mPa.s, 50 mPa.s, 100 mPa.s, 150 mPa.s, 200 mPa.s, 250 mPa.s, 300 mPa.s, 350 mPa.s, 400 mPa.s, 450 mPa.s, 500 mPa.s, and specific point values ​​between the above point values. Due to limited space and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0053] In one embodiment, the particle size of the binder is 20-200 nm, for example, it can be 20 nm, 50 nm, 100 nm, 150 nm, 200 nm, and specific point values ​​between the above point values. Due to limited space and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0054] In one embodiment, the conductive coating material further comprises, by weight: 0.3-1 parts of a dispersant and 3-20 parts of a wetting agent.

[0055] In one embodiment, the weight portion of the dispersant is 0.3-1 part, for example, it can be 0.3 part, 0.5 part, 0.8 part, 1 part, and specific point values ​​between the above point values. Due to limited space and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0056] In one embodiment, the weight portion of the wetting agent is 3-20 parts, for example, it can be 3 parts, 5 parts, 10 parts, 15 parts, 20 parts, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0057] In one embodiment, the dispersant includes sodium carboxymethylcellulose and / or potassium carboxymethylcellulose.

[0058] In one embodiment, the wetting agent includes any one of isopropyl alcohol, propylene glycol, n-octanol, polyethylene glycol, or polyoxyethylene ether, or a combination of at least two thereof.

[0059] In one embodiment, the foil material includes any one of aluminum foil, titanium foil or composite aluminum foil, or a combination of at least two of them.

[0060] In one embodiment, the raw materials for preparing the conductive coating include a solvent.

[0061] In one embodiment, the solvent comprises water.

[0062] In a fourth aspect, an embodiment of the present application provides a method for preparing the water-resistant carbon-coated current collector as described in the third aspect, the preparation method comprising:

[0063] (1) mixing the modified conductive carbon material with a binder to obtain a modified conductive slurry;

[0064] (2) coating the modified conductive slurry obtained in step (1) on the surface of the foil and drying it to obtain the water-resistant carbon-coated current collector.

[0065] In one embodiment, the mixed materials in step (1) further include a dispersant, a wetting agent, and a solvent.

[0066] In one embodiment, the mixing in step (1) is performed under stirring.

[0067] In one embodiment, the stirring rate is 10-60 rpm, for example, it can be 10 rpm, 20 rpm, 30 rpm, 40 rpm, 50 rpm, 60 rpm, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0068] In one embodiment, the mixing temperature is 15-30°C, for example, it can be 15°C, 18°C, 20°C, 22°C, 26°C, 28°C, 30°C, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0069] In one embodiment, the mixing time is 10-60 min, for example, it can be 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0070] In one embodiment, the coating comprises dispersing using a homogenizer bar.

[0071] As an optional technical solution for the embodiment of the present application, a homogenizing rod is used to disperse the SBR on the surface of the slurry. The homogenizing rod is generally a hollow rod made of aluminum alloy with continuous spiral protrusions on the surface. There are magnetic materials and rubber spacers at both ends. It can be adsorbed on the plate roller but will not stick to the plate roller. The homogenizing rod floats on the surface of the slurry. When the plate roller rotates, it rotates in the opposite direction due to the adsorption effect. During rotation, the ripples drive the surface of the slurry, making the surface move, thereby evenly dispersing the SBR on the surface of the slurry and avoiding blue drift.

[0072] In one embodiment, the coating rate in step (2) is 30-150 m / min, for example, it can be 30 m / min, 40 m / min, 50 m / min, 80 m / min, 100 m / min, 120 m / min, 150 m / min, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0073] In one embodiment, the coating thickness in step (2) is ≤2 μm on a single side, for example, it can be 0.5 μm, 1 μm, 1.5 μm, 2 μm, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0074] In one embodiment, the drying temperature in step (2) is 75-120°C, for example, it can be 75°C, 80°C, 90°C, 100°C, 110°C, 120°C, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0075] In one embodiment, the drying time in step (2) is 10-60 min, for example, it can be 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the embodiments of this application no longer exhaustively list the specific point values ​​included in the range.

[0076] A high oven temperature or a long oven time helps to increase the crosslinking degree of the styrene-butadiene rubber latex and improve the adhesion and water resistance of the carbon-coated current collector.

[0077] The coating of conductive carbon materials with silane coupling agent can interact with both the hydroxyl groups in inorganic substances and the long molecular chains in organic polymers, coupling the two materials with different properties. It can not only increase the cross-linking degree of styrene-butadiene rubber latex, enhance water resistance, strengthen the adhesion between metal foil and conductive materials, but also enhance the wettability of the slurry on the foil.

[0078] In one embodiment, the method for preparing the water-resistant carbon-coated current collector specifically includes:

[0079] (1) Prepare a dispersant aqueous solution, add the dispersant to the remaining solvent water until it is completely dissolved to form a transparent solution;

[0080] (2) adding the modified conductive carbon material to the dispersant aqueous solution in the previous step in equal portions to obtain a conductive carbon aqueous solution;

[0081] (3) slowly adding a wetting agent to the conductive carbon aqueous solution in the previous step to obtain a mixed solution;

[0082] (4) homogenizing or sand-milling the mixed solution in the previous step to obtain a dispersed mixed solution;

[0083] (5) adding a binder to the dispersed mixed solution in the previous step, stirring and dispersing at a low speed, and then adding a wetting agent to obtain a mixed slurry;

[0084] (6) vacuuming the mixed slurry in the previous step to obtain a modified conductive slurry;

[0085] (7) The modified conductive paste in the previous step is coated on the above-mentioned foil through a coating machine, and then rolled up after drying to obtain a water-resistant carbon-coated current collector.

[0086] There is no fixed requirement for the stirring and dispersing speed of the dispersant aqueous solution in the above step (1). The higher the stirring speed, the faster the dissolution time, while the lower the stirring speed, the slower the dissolution time.

[0087] The dispersed mixed solution in the above step (4) has a D50 of <1.2 μm and a D90 of <5 μm.

[0088] In the above step (7), the modified conductive slurry is placed in the coating machine trough, and the coating machine trough is equipped with a homogenizing rod, the length of which exceeds the length of the plate roller by 2-4 cm; after being broken up, the blueing problem caused by SBR in the modified conductive slurry is reduced, and the consistency of the slurry on the screen roller is ensured. The homogenizing rod is a hollow rod made of aluminum alloy, with spiral continuous protrusions on the surface, magnetic materials and rubber spacers at both ends, which can be adsorbed on the plate roller but will not stick to the plate roller. The modified conductive slurry is coated in the coating machine, and the foil is first subjected to corona and / or preheating oven to remove the oil on the foil surface and increase the dyne value of the foil, wherein the corona power is not less than 6KW.

[0089] This application has the following beneficial effects:

[0090] The modified conductive carbon material provided in the present application uses a macromolecular surface treatment agent methyl methacrylate-butyl acrylate-polymerizable silane coupling agent terpolymer to modify the surface of the conductive carbon material. The polar bonds of the terpolymer act physically and chemically on the conductive carbon material to form hydrogen bonds, thereby reducing the surface free energy of the carbon material powder, alleviating agglomeration, greatly reducing the particle size, and significantly weakening the hydrophobicity. Through the cross-linking reaction of hydroxyl and carboxyl groups and double bonds in SBR, the affinity with SBR is increased, the cross-linking degree with SBR is improved, and the SBR tends to be stable in the slurry. The carbon-coated current collector prepared with the modified conductive carbon material improves the coating film surface stripe problem caused by the instability of styrene-butadiene rubber latex in the slurry, while enhancing water resistance and being resistant to water wiping 51-88 times. DETAILED DESCRIPTION

[0091] The technical solution of the present application is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0092] The experimental materials used in the examples and comparative examples of this application are as follows:

[0093] (1) Styrene-butadiene latex, brand 350HC, manufactured by SUNROSE, Japan;

[0094] (2) Conductive carbon material SPLi, brand SUPER P LI, manufacturer IMERYS;

[0095] (3) Conductive graphite KS6, brand TIMREX KS 6, manufacturer IMERYS;

[0096] (4) Carbon nanotubes, brand XFM04, manufactured by Xianfeng Nano;

[0097] Example 1

[0098] This embodiment provides a modified conductive carbon material and a preparation method thereof. The raw materials for preparing the modified conductive carbon material include, by mass: 70g methyl methacrylate, 20g butyl acrylate, 4g polymerizable silane coupling agent KH-570, 10g conductive carbon material SPLi, 0.1g first initiator benzoyl peroxide, 0.2g second initiator isopropyl benzene peroxide, 6g of a first solvent toluene aqueous solution with a concentration of 0.5mg / L, and 0.1g second solvent acetone;

[0099] The preparation method of the modified conductive carbon material is specifically as follows:

[0100] (1) According to the above formula, methyl methacrylate (MMA), butyl acrylate (BA), polymerizable silane coupling agent (KH-570) and toluene were added in sequence to a three-necked flask equipped with a stirrer, a condenser and a nitrogen connecting tube. After sufficient stirring, the temperature was raised to 80°C. The first initiator, benzoyl peroxide, was gradually added dropwise. The temperature was kept at 85°C for 2 hours. The second initiator, cumyl peroxide, was then added. The temperature was raised to 115°C and kept for 2 hours. After cooling, a terpolymer solution was obtained.

[0101] The conductive carbon material SPLi was placed into the ternary copolymer solution in the above three-necked flask, acetone was added, ultrasonic dispersion was performed for 15 minutes, and then high-speed stirring was carried out at 80°C for 3 hours under nitrogen protection. After cooling, it was placed in a 50°C oven under vacuum drying for 12 hours to obtain the modified conductive carbon material SPLi.

[0102] This embodiment also provides a water-resistant carbon-coated current collector, which includes a foil (aluminum foil) and a conductive coating provided on the surface of the foil, wherein the conductive coating includes the aforementioned modified conductive carbon material. The specific preparation method is as follows:

[0103] (1) Add 0.5 g of dispersant sodium carboxymethyl cellulose to the solvent water and stir until it is completely dissolved to form a transparent solution;

[0104] (2) 5 g of the modified conductive material SP-Li was added to the dispersant aqueous solution in step (1) in two equal portions, with a stirring speed of 60 rpm and a dispersion speed of 4000 rpm in a dual planetary mixer at a temperature of 25 ± 5 ° C. Each time for 15 min to obtain a conductive carbon aqueous solution;

[0105] (3) Slowly add 15 g of isopropyl alcohol as a wetting agent to the conductive carbon aqueous solution in step (2) at a stirring speed of 60 rpm, a dispersion speed of 4000 rpm, a temperature of 25 ± 5 ° C, and a time of 30 min to obtain a mixed solution;

[0106] (4) The mixed solution in step (3) was subjected to a homogenizer to particle size treatment, and after treatment, D50 = 0.886 μm, D90 = 4.34 μm, to obtain a dispersed mixed solution;

[0107] (5) 7 g of a binder styrene-butadiene rubber latex (solid content 45%, viscosity <100 mPa.s, particle size D90 160 nm) was added to the dispersed mixed solution in step (4) at a stirring speed of 30 rpm and a dispersion speed of 500 rpm in a dual planetary mixer at a temperature of 25 ± 5 °C for 15 min to obtain a mixed slurry;

[0108] (6) The mixed slurry in step (5) was vacuumed, and the reverse stirring speed of the double planetary mixer was 10 rpm, the vacuum degree was <-0.07 KPa, the temperature was 25±5°C, and the time was 30 min to obtain a modified conductive slurry (solid content was 8.5%, and the slurry pH was 7.1).

[0109] (7) The modified conductive paste in step (6) is coated on a double-sided smooth aluminum foil by a coating machine. The aluminum foil is pretreated with a corona machine. The coating speed is 50 m / min, the coating thickness on one side is 1±0.2 μm, and the oven temperature is 100° C. for 15 min. The water-resistant carbon-coated current collector is rolled up.

[0110] Example 2

[0111] This embodiment provides a modified conductive carbon material and a preparation method thereof. The raw materials for preparing the modified conductive carbon material include, by mass: 70g of methyl methacrylate, 20g of butyl acrylate, 4g of a polymerizable silane coupling agent KH-570, 10g of a conductive carbon material (the mass ratio of SP-Li to conductive graphite SK6 is 8:2), 0.1g of a first initiator benzoyl peroxide, 0.2g of a second initiator isopropyl benzene peroxide, 6g of an aqueous solution of a first solvent toluene with a concentration of 0.5mg / L, and 0.1g of a second solvent acetone;

[0112] The preparation method of the modified conductive carbon material is specifically as follows:

[0113] (1) According to the above formula, methyl methacrylate (MMA), butyl acrylate (BA), polymerizable silane coupling agent (KH-570) and toluene were added in sequence to a three-necked flask equipped with a stirrer, a condenser and a nitrogen connecting tube. After sufficient stirring, the temperature was raised to 80°C. The first initiator, benzoyl peroxide, was gradually added dropwise. The temperature was kept at 85°C for 2 hours. The second initiator, cumyl peroxide, was then added. The temperature was raised to 115°C and kept for 2 hours. After cooling, a terpolymer solution was obtained.

[0114] The conductive carbon material (SP-Li and conductive graphite SK6 mass ratio of 8:2) was placed in the ternary copolymer solution in the above three-necked flask, acetone was added, ultrasonic dispersion was performed for 15 minutes, and then high-speed stirring was carried out at 80°C under nitrogen protection for 3 hours. After cooling, it was placed in a 50°C oven under vacuum drying for 12 hours to obtain a modified conductive carbon material.

[0115] This embodiment also provides a water-resistant carbon-coated current collector, which includes a foil (aluminum foil) and a conductive coating provided on the surface of the foil, wherein the conductive coating includes the aforementioned modified conductive carbon material. The specific preparation method is as follows:

[0116] (1) Add 0.5 g of dispersant sodium carboxymethyl cellulose to the solvent water and stir until it is completely dissolved to form a transparent solution;

[0117] (2) 5 g of the modified conductive material was added to the dispersant aqueous solution in step (1) in two equal portions, with a stirring speed of 60 rpm and a dispersion speed of 4000 rpm in a dual planetary mixer at a temperature of 25 ± 5 ° C. Each time was 15 min to obtain a conductive carbon aqueous solution;

[0118] (3) Slowly add 15 g of isopropyl alcohol as a wetting agent to the conductive carbon aqueous solution in step (2) at a stirring speed of 60 rpm, a dispersion speed of 4000 rpm, a temperature of 25 ± 5 ° C, and a time of 30 min to obtain a mixed solution;

[0119] (4) The mixed solution in step (3) was subjected to a homogenizer to particle size treatment, and after treatment, D50 = 0.912 μm, D90 = 4.12 μm, to obtain a dispersed mixed solution;

[0120] (5) 11 g of a binder styrene-butadiene rubber latex (solid content 45%, viscosity <100 mPa.s, particle size D90 160 nm) was added to the dispersed mixed solution in step (4) at a stirring speed of 30 rpm and a dispersion speed of 800 rpm in a dual planetary mixer at a temperature of 25 ± 5 °C for 20 min to obtain a mixed slurry;

[0121] (6) The mixed slurry in step (5) was vacuumed, and the reverse stirring speed of the double planetary mixer was 10 rpm, the vacuum degree was <-0.07 KPa, the temperature was 25±5°C, and the time was 30 min to obtain a modified conductive slurry (solid content of 10.05%, slurry pH of 6.9).

[0122] (7) The modified conductive paste in step (6) is coated on a double-sided smooth aluminum foil by a coating machine. The aluminum foil is pretreated with a corona machine. The coating speed is 80m / min, the coating thickness on one side is 1±0.2um, and the oven temperature is 120℃ for 10min. The water-resistant carbon-coated current collector is rolled up.

[0123] Example 3

[0124] This embodiment provides a modified conductive carbon material and a preparation method thereof. The raw materials for preparing the modified conductive carbon material include, by mass: 80g of methyl methacrylate, 10g of butyl acrylate, 5g of a polymerizable silane coupling agent KH-570, 10g of a conductive carbon material (the mass ratio of SP-Li, conductive graphite SK6, and carbon nanotubes is 8:1.9:0.1), 0.2g of a first initiator, benzoyl peroxide, 0.2g of a second initiator, isopropyl benzene peroxide, 6g of an aqueous solution of a first solvent, toluene, with a concentration of 0.5mg / L, and 0.1g of a second solvent, acetone;

[0125] The preparation method of the modified conductive carbon material is specifically as follows:

[0126] (1) According to the above formula, methyl methacrylate (MMA), butyl acrylate (BA), polymerizable silane coupling agent (KH-570) and toluene were added in sequence to a three-necked flask equipped with a stirrer, a condenser and a nitrogen connecting tube. After sufficient stirring, the temperature was raised to 80°C. The first initiator, benzoyl peroxide, was gradually added dropwise. The temperature was kept at 85°C for 2 hours. The second initiator, cumyl peroxide, was then added. The temperature was raised to 115°C and kept for 2 hours. After cooling, a terpolymer solution was obtained.

[0127] The conductive carbon material (the mass ratio of SP-Li, conductive graphite SK6 and carbon nanotubes is 8:1.9:0.1) is placed in the ternary copolymer solution in the above three-necked flask, acetone is added, and ultrasonic dispersion is performed for 15 minutes. Then, the mixture is stirred at high speed at 80°C under nitrogen protection for 3 hours. After cooling, the mixture is placed in a 50°C oven and vacuum dried for 12 hours to obtain a modified conductive carbon material.

[0128] This embodiment also provides a water-resistant carbon-coated current collector, which includes a foil (aluminum foil) and a conductive coating provided on the surface of the foil, wherein the conductive coating includes the aforementioned modified conductive carbon material. The specific preparation method is as follows:

[0129] (1) Add 0.3 g of dispersant sodium carboxymethyl cellulose to the solvent water and stir until it is completely dissolved to form a transparent solution;

[0130] (2) adding the aforementioned 10 g modified conductive material into the dispersant aqueous solution in step (1) in two equal portions, with a stirring speed of 60 rpm and a dispersion speed of 4000 rpm in a dual planetary mixer at a temperature of 25 ± 5 ° C. for 15 min each time to obtain a conductive carbon aqueous solution;

[0131] (3) Slowly add 10 g of isopropyl alcohol as a wetting agent to the conductive carbon aqueous solution in step (2) at a stirring speed of 60 rpm, a dispersion speed of 4000 rpm, a temperature of 25 ± 5 ° C, and a time of 30 min to obtain a mixed solution;

[0132] (4) The mixed solution in step (3) was subjected to a homogenizer to particle size treatment, and after treatment, D50 = 1.193 μm, D90 = 4.57 μm, to obtain a dispersed mixed solution;

[0133] (5) 7 g of a binder styrene-butadiene rubber latex (solid content of 45%, viscosity <200 mPa.s, particle size D90 of 145 nm) was added to the dispersed mixed solution in step (4) at a stirring speed of 30 rpm and a dispersion speed of 800 rpm in a dual planetary mixer at a temperature of 25 ± 5 °C for 20 min to obtain a mixed slurry;

[0134] (6) The mixed slurry in step (5) was vacuumed, and the reverse stirring speed of the double planetary mixer was 10 rpm, the vacuum degree was <-0.07 KPa, the temperature was 25±5°C, and the time was 30 min to obtain a modified conductive slurry (solid content was 13.45%, and the slurry pH was 7.3).

[0135] (7) The modified conductive paste in step (6) is coated on a double-sided smooth aluminum foil by a coating machine. The aluminum foil is pre-treated with a corona machine. The coating speed is 40m / min, the coating thickness on one side is 2±0.2um, and the oven temperature is 120℃ for 20min. The water-resistant carbon-coated current collector is rolled up.

[0136] Example 4

[0137] This embodiment provides a modified conductive carbon material and a preparation method thereof. The preparation method differs from that of Example 1 only in that the first insulation temperature is 80°C and the time is 3 hours; the types, amounts and preparation methods of other components are the same as those of Example 1.

[0138] This embodiment also provides a water-resistant carbon-coated current collector, which differs from the water-resistant carbon-coated current collector in Example 1 only in that the modified conductive carbon material provided in this embodiment is used in the conductive coating; the types, amounts and preparation methods of its components are the same as those in Example 1.

[0139] Example 5

[0140] This embodiment provides a modified conductive carbon material and a preparation method thereof. The preparation method differs from that of Example 1 only in that the second insulation temperature is 120 degrees Celsius and the time is 1 hour; the types, amounts and preparation methods of other components are the same as those of Example 1.

[0141] This embodiment also provides a water-resistant carbon-coated current collector, which differs from the water-resistant carbon-coated current collector in Example 1 only in that the modified conductive carbon material provided in this embodiment is used in the conductive coating; the types, amounts and preparation methods of its components are the same as those in Example 1.

[0142] Example 6

[0143] This embodiment provides a modified conductive carbon material and a preparation method thereof. The preparation method differs from that of Example 1 only in that the reaction temperature is 90° C. and the reaction time is 2 hours; the types, amounts and preparation methods of other components are the same as those of Example 1.

[0144] This embodiment also provides a water-resistant carbon-coated current collector, which differs from the water-resistant carbon-coated current collector in Example 1 only in that the modified conductive carbon material provided in this embodiment is used in the conductive coating; the types, amounts and preparation methods of its components are the same as those in Example 1.

[0145] Example 7

[0146] This embodiment provides a modified conductive carbon material and a preparation method thereof. The preparation method differs from that of Example 1 only in that the drying temperature is 60° C. and the drying time is 10 hours; the types, amounts and preparation methods of other components are the same as those of Example 1.

[0147] This embodiment also provides a water-resistant carbon-coated current collector, which differs from the water-resistant carbon-coated current collector in Example 1 only in that the modified conductive carbon material provided in this embodiment is used in the conductive coating; the types, amounts and preparation methods of its components are the same as those in Example 1.

[0148] Comparative Example 1

[0149] This comparative example provides a carbon-coated current collector, which differs from Example 1 only in that the conductive carbon material is unmodified SPLi; the types, amounts and preparation methods of other components are the same as those in Example 1.

[0150] Comparative Example 2

[0151] This comparative example provides a carbon-coated current collector, which differs from Example 2 only in that the conductive carbon material is unmodified SP-Li and conductive graphite SK6, wherein the mass ratio of SP-Li to conductive graphite SK6 is 8:2; the types, amounts and preparation methods of other components are the same as those in Example 2.

[0152] Comparative Example 3

[0153] This comparative example provides a carbon-coated current collector, which differs from Example 3 only in that the conductive carbon material is unmodified SP-Li, conductive graphite SK6 and carbon nanotubes, wherein the mass ratio of SP-Li to conductive graphite SK6 and carbon nanotubes is 8:1.9:0.1; the types, amounts and preparation methods of other components are the same as those in Example 3.

[0154] Comparative Example 4

[0155] This comparative example provides a modified conductive carbon material and a preparation method thereof. The preparation method differs from that of Example 1 only in that butyl acrylate is not added; the types, amounts and preparation methods of other components are the same as those of Example 1.

[0156] This comparative example also provides a water-resistant carbon-coated current collector, which differs from the water-resistant carbon-coated current collector in Example 1 only in that the modified conductive carbon material provided in this comparative example is used in the conductive coating; the types, amounts and preparation methods of its components are the same as those in Example 1.

[0157] Comparative Example 5

[0158] This comparative example provides a modified conductive carbon material and a preparation method thereof. The preparation method differs from that of Example 1 only in that methyl methacrylate is not added; the types, amounts and preparation methods of other components are the same as those of Example 1.

[0159] This comparative example also provides a water-resistant carbon-coated current collector, which differs from the water-resistant carbon-coated current collector in Example 1 only in that the modified conductive carbon material provided in this comparative example is used in the conductive coating; the types, amounts and preparation methods of its components are the same as those in Example 1.

[0160] Comparative Example 6

[0161] This comparative example provides a modified conductive carbon material and a preparation method thereof. The preparation method differs from that of Example 1 only in that no polymerizable silane coupling agent is added; the types, amounts and preparation methods of other components are the same as those of Example 1.

[0162] This comparative example also provides a water-resistant carbon-coated current collector, which differs from the water-resistant carbon-coated current collector in Example 1 only in that the modified conductive carbon material provided in this comparative example is used in the conductive coating; the types, amounts and preparation methods of its components are the same as those in Example 1.

[0163] Comparative Example 7

[0164] This comparative example provides a modified conductive carbon material and a preparation method thereof. The preparation method differs from that of Example 1 only in that the amount of polymerizable silane coupling agent KH-570 used is 20 g; the types, amounts and preparation methods of other components are the same as those of Example 1.

[0165] This comparative example also provides a water-resistant carbon-coated current collector, which differs from the water-resistant carbon-coated current collector in Example 1 only in that the modified conductive carbon material provided in this comparative example is used in the conductive coating; the types, amounts and preparation methods of its components are the same as those in Example 1.

[0166] The performance of the carbon-coated current collectors obtained in Examples 1-7 and Comparative Examples 1-7 was tested using the following method:

[0167] (1) Surface resistance (place a 10 cm*10 cm sample flat and test it with a four-probe resistance tester);

[0168] (2) Peel strength (use 3M double-sided tape to adhere the foil to the surface of the steel plate, adhere 3M610 tape to the other side, fix the steel plate and the other end of the 3M610 tape, and perform the peel test at a speed of 50 mm / min);

[0169] (3) Water-resistant wiping (fix the carbon-coated foil on a table, press a 25g weight + a 55g adjustment rod (80g in total) on a cotton swab soaked in pure water, apply a force F to pull the weight and the adjustment rod back and forth to allow the cotton swab to wipe the coated surface of the carbon-coated foil, observe whether the coating changes color or falls off, and record the number of wipes);

[0170] (4) Hydrolysis resistance after immersion for 24 h (the carbon-coated foil was completely immersed in pure water and the shedding of the carbon coating was observed after 24 h);

[0171] (5) Stripes: Observe with the eyes;

[0172] The various properties of the carbon-coated current collectors obtained in Examples 1-7 and Comparative Examples 1-7 were tested according to the above-mentioned performance testing method. The test results are shown in Table 1.

[0173] Table 1

[0174] From the data in Table 1, it can be seen that Examples 1-7 are prepared by preparing a slurry through a modified conductive material and using an ink-distributing rod to assist in coating the slurry. Compared with Comparative Examples 1-3, the water wiping resistance is significantly improved, and the water wiping resistance can reach 51-88 times, and there is no streak on the film surface. At the same time, the surface resistance and peeling force are basically the same; relative to Example 1, Comparative Example 4 lacks butyl acrylate for softening, and the coating prepared by the modified conductive carbon material is brittle after drying. Although there is no streak, the peeling force is significantly reduced; for Example 1, Comparative Example 5 lacks methyl methacrylate, which causes the modified conductive agent to agglomerate and increase the viscosity, resulting in a significant increase in the coating resistance and obvious coating streaks; for Example 1, Comparative Example 6 lacks a polymerizable silane coupling agent, which causes the conductive agent to be weakly modified, weakly bonded to the styrene-butadiene rubber latex, and obvious coating streaks; for Example 1, Comparative Example 7, the addition of an excessive amount of polymerizable silane coupling agent causes the conductive agent to agglomerate, making it difficult to disperse, and weakly bonded to the styrene-butadiene rubber latex, resulting in reduced coating peeling force, reduced water wiping times, and obvious streaks.

[0175] The applicant declares that this application uses the above-mentioned embodiments to illustrate a modified conductive carbon material, its preparation method, and its application. However, this application is not limited to the above-mentioned embodiments, which does not mean that this application must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvements to this application, equivalent replacements for various raw materials of the product of this application, addition of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of this application.

Claims

1. A modified conductive carbon material, wherein the raw materials for preparing the modified conductive carbon material include, by weight: 60-80 parts of methyl methacrylate, 10-20 parts of butyl acrylate, 1-5 parts of polymerizable silane coupling agent, 5-10 parts of conductive carbon material, 0.1-0.2 parts of first initiator, 0.1-0.3 parts of second initiator, 1-10 parts of first solvent, 0.1-1 parts of second solvent.

2. The modified conductive carbon material according to claim 1, wherein The polymerizable silane coupling agent includes any one of γ-methacryloxypropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(methoxyethoxy)silane or aminopropyltriethoxysilane, or a combination of at least two thereof; Optionally, the conductive carbon material includes any one or a combination of at least two of conductive carbon black, conductive graphite, carbon nanotubes, carbon nanofibers or graphene; Optionally, the first initiator comprises benzoyl peroxide; Optionally, the second initiator comprises cumene peroxide; Optionally, the first solvent comprises toluene; Optionally, the first solvent is an aqueous solution of toluene; Optionally, the concentration of toluene in the aqueous solution of toluene is 0.5-1 mg / L; Optionally, the second solvent comprises acetone.

3. A method for preparing the modified conductive carbon material according to claim 1 or 2, the preparation method comprising: Methyl methacrylate, butyl acrylate, a silane coupling agent, a conductive carbon material, a first initiator, a second initiator, a first solvent, and a second solvent are mixed and reacted to obtain the modified conductive carbon material.

4. The preparation method according to claim 3, wherein The preparation method specifically comprises: mixing methyl methacrylate, butyl acrylate, a silane coupling agent, and a first solvent, adding a first initiator, keeping the temperature for the first time, adding a second initiator, keeping the temperature for the second time, and cooling to obtain a terpolymer solution; mixing the terpolymer solution with a conductive carbon material and a second solvent, reacting, and obtaining the modified conductive carbon material; Optionally, the temperature of the first insulation is 80-90° C.; Optionally, the first insulation time is 1-3h; Optionally, the temperature of the second insulation is 110-120°C; Optionally, the second insulation time is 1-3h; Optionally, the reaction temperature is 70-90°C; Optionally, the reaction time is 2-4h; Optionally, the reaction further includes cooling and drying; Optionally, the drying temperature is 40-60°C; Optionally, the drying time is 10-15 hours.

5. A water-resistant carbon-coated current collector, comprising a foil and a conductive coating disposed on the surface of the foil, wherein the conductive coating comprises a combination of the modified conductive carbon material as described in claim 1 or 2 and a binder.

6. The water-resistant carbon-coated current collector according to claim 5, wherein: The materials of the conductive coating include, by weight: 5-10 parts of the modified conductive carbon material and 7-22 parts of a binder; Optionally, the binder includes styrene-butadiene rubber latex; Optionally, the solid content of the styrene-butadiene rubber latex is 40-50%; Optionally, the viscosity of the binder is 5-500 mpa.s; Optionally, the particle size of the binder is 20-200 nm.

7. The water-resistant carbon-coated current collector according to claim 6, wherein: The conductive coating material also includes, by weight: 0.3-1 part of a dispersant and 3-20 parts of a wetting agent; Optionally, the dispersant comprises sodium carboxymethyl cellulose and / or potassium carboxymethyl cellulose; Optionally, the wetting agent includes any one of isopropyl alcohol, propylene glycol, n-octanol, polyethylene glycol or polyoxyethylene ether, or a combination of at least two thereof.

8. The water-resistant carbon-coated current collector according to any one of claims 5 to 7, wherein: The foil material includes any one of aluminum foil, titanium foil or composite aluminum foil, or a combination of at least two of them.

9. A method for preparing a water-resistant carbon-coated current collector according to any one of claims 5 to 8, the method comprising: (1) mixing the modified conductive carbon material with a binder to obtain a modified conductive slurry; (2) coating the modified conductive slurry obtained in step (1) on the surface of the foil and drying it to obtain the water-resistant carbon-coated current collector.

10. The preparation method according to claim 9, wherein: The mixed materials in step (1) further include a dispersant, a wetting agent, and a solvent; Optionally, the mixing in step (1) is performed under stirring; Optionally, the stirring rate is 10-5000 rpm; Optionally, the mixing temperature is 15-30°C; Optionally, the mixing time is 10-60min; Optionally, the coating includes dispersing using a homogenizer bar; Optionally, the coating rate in step (2) is 30-150 m / min; Optionally, the coating thickness in step (2) is ≤2 μm on a single side; Optionally, the drying temperature in step (2) is 75-120°C; Optionally, the drying time in step (2) is 10 min to 60 min.

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