Carbon-coated current collector, and preparation method therefor and use thereof

Abstract

A carbon-coated current collector. The carbon-coated current collector comprises a foil and a conductive coating arranged on the surface of the foil. The conductive coating comprises a combination of a modified conductive carbon material and a binder. The binder is prepared from the following raw materials in parts by weight: 40-60 parts of methyl isobutyl ketone, 25-30 parts of a solvent, 20-25 parts of isobornyl methacrylate, 20-25 parts of methyl methacrylate, 20-25 parts of n-butyl acrylate, 20-25 parts of hydroxyethyl acrylate, 18-22 parts of silicone oil, and 50-55 parts of an initiator. The modified conductive carbon material is a fluorosilane-modified carbon material. The modified conductive carbon material and the binder can form silanols by means of hydrolysis reaction of respective alkoxy groups, then the silanols form new hydrogen bonds with OH groups, and covalent bonds are formed on the surface of the carbon material, thereby forming a highly cross-linked network structure, which further enhances water resistance, allowing for the ability to withstand 200 or more wiping operations.

Description

A carbon-coated current collector and its preparation method and application Technical Field

[0001] The embodiments of the present application relate to the field of lithium-ion battery technology, such as a carbon-coated current collector and its preparation method and application. Background Art

[0002] 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.

[0003] Among them, under the trend of environmental protection requirements, the positive electrode active material coating of lithium-ion secondary batteries has gradually developed from the original oily system to the aqueous system; while the aqueous secondary batteries sodium-ion batteries developed in recent years have both positive and negative electrode active material coatings in aqueous systems, which have higher requirements for the water resistance of the current collector coating.

[0004] Currently, the most water-resistant and hydrophobic binder used in lithium-ion batteries is styrene-butadiene latex (SBR). While SBR provides a certain degree of water resistance when used as a binder in the carbon-coated current collector slurry, it is unstable in the slurry, exhibiting a bluing effect. This results in poor coating consistency and weak water resistance.

[0005] CN113140706A provides a battery carbonization process and a method for preparing a lithium-ion battery. The battery carbonization process includes 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, 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 method for preparing a lithium-ion battery comprises performing a carbonization treatment on the inner surface of a small cylindrical steel or aluminum shell battery, thereby improving the electronic conductivity of the current collector and active material of 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 space utilization within the lithium-ion battery. CN110034302A discloses an ultra-thin carbon-coated current collector and a preparation method thereof, comprising the following steps: cleaning the current collector and then subjecting it to positive charging treatment to obtain a current collector with a positive charge on the surface; dissolving the binder, sequentially adding anionic surfactant and conductive agent, and stirring evenly to form a negatively charged aqueous conductive slurry; ultrasonically atomizing the negatively charged aqueous conductive slurry into an aerosol, electrostatically depositing it on the positively charged current collector, and then drying it to obtain an ultra-thin carbon-coated current collector with a thin and uniform conductive coating, strong adhesion, and good conductive properties.

[0006] Since the carbon-coated current collectors in the related art have problems such as poor water resistance, it is an urgent problem to be solved in the art to develop a carbon-coated current collector with good water resistance without using styrene-butadiene rubber latex binder.

[0007] Summary of the Invention

[0008] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0009] The embodiment of the present application provides a carbon-coated current collector and its preparation method and application. Through a binder and a modified conductive carbon material, silicone oil is introduced into the binder, which contains alkoxy hydrolysis substituents to make it have a certain water resistance. Fluorosilane is introduced into the modified conductive carbon material, which contains fluorinated hydrocarbons and can induce hydrophobicity to further enhance water resistance.

[0010] In the first aspect, an embodiment of the present application provides a carbon-coated current collector, which includes a foil and a conductive coating provided on the surface of the foil, wherein the conductive coating includes a combination of a modified conductive carbon material and a binder, and the raw materials for preparing the binder include, by weight: 40-60 parts of methyl isobutyl ketone, 25-30 parts of solvent, 20-25 parts of isobornyl methacrylate, 20-25 parts of methyl methacrylate, 20-25 parts of n-butyl acrylate, 20-25 parts of hydroxyethyl acrylate, 18-22 parts of silicone oil, and 50-55 parts of initiator; the modified conductive carbon material is a fluorosilane-modified carbon material.

[0011] Preferably, the weight portion of the methyl isobutyl ketone is 40-60 parts, for example, 40 parts, 45 parts, 50 parts, 55 parts, 60 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.

[0012] Preferably, the weight portion of the solvent is 25-30 parts, for example, it can be 25 parts, 27 parts, 29 parts, 30 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.

[0013] Preferably, the weight proportion of the isobornyl methacrylate is 20-25 parts, for example, it can be 20 parts, 22 parts, 23 parts, 25 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.

[0014] Preferably, the weight portion of the methyl methacrylate is 20-25 parts, for example, it can be 20 parts, 22 parts, 23 parts, 25 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.

[0015] Preferably, the weight portion of n-butyl acrylate is 20-25 parts, for example, it can be 20 parts, 22 parts, 23 parts, 25 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.

[0016] Preferably, the weight portion of the hydroxyethyl acrylate is 20-25 parts, for example, it can be 20 parts, 22 parts, 23 parts, 25 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.

[0017] Preferably, the weight portion of the silicone oil is 18-22 parts, for example, it can be 18 parts, 20 parts, 22 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] Preferably, the weight portion of the initiator is 50-55 parts, for example, it can be 50 parts, 51 parts, 52 parts, 53 parts, 55 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.

[0019] Preferably, the solvent comprises toluene.

[0020] Preferably, the initiator comprises azobisisobutyronitrile.

[0021] The adhesive is synthesized by reacting isobornyl methacrylate monomer, methyl methacrylate monomer, n-butyl acrylate monomer, hydroxyethyl acrylate monomer and silicone oil (triisopropoxyvinylsilane). When used, the introduction of silicone oil contains alkoxy hydrolysis substituents, which makes it have a certain water resistance.

[0022] Preferably, the silicone oil includes any one of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methylphenyl silicone oil, methylchlorophenyl silicone oil, methylethoxy silicone oil, methyltrifluoropropyl silicone oil, methylvinyl silicone oil, methylhydroxy silicone oil, ethyl hydrogen silicone oil or hydroxy hydrogen silicone oil, or a combination of at least two thereof.

[0023] Preferably, the fluorosilane comprises heptadecafluorodecyltrimethoxysilane;

[0024] Preferably, the fluorosilane includes organic silicon having less than 10 carbon atoms and more than 10 fluorine atoms.

[0025] Preferably, the mass ratio of the fluorosilane to the carbon material is 1:(4-6), for example, it can be 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 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 range.

[0026] Fluorosilanes, which contain fluorinated hydrocarbons that induce hydrophobicity, also contain alkoxy hydrolysis substituents. The modified conductive carbon material and modified acrylic resin can then hydrolyze their respective alkoxy groups to form silanols, which then form new hydrogen bonds with OH groups and covalent bonds on the carbon material surface, forming a highly cross-linked network structure that further enhances water resistance.

[0027] Preferably, the modified conductive coating material comprises, by weight: 5-10 parts of modified conductive carbon material, 7-22 parts of binder, and 3-20 parts of wetting agent.

[0028] Preferably, the weight proportion of the modified conductive carbon material is 5-10 parts, for example, it can be 5 parts, 7 parts, 9 parts, 10 parts, and specific values ​​between the above points. Due to limited space and for the sake of simplicity, this application no longer exhaustively lists the specific points included in the range.

[0029] Preferably, the weight proportion of the binder is 7-22 parts, for example, 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 brevity, this application no longer exhaustively lists the specific values ​​included in the range.

[0030] Preferably, 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, this application no longer exhaustively lists the specific point values ​​included in the range.

[0031] Preferably, the carbon material includes any one of conductive carbon black, conductive graphite, carbon nanotubes, carbon nanofibers or graphene, or a combination of at least two of them.

[0032] Preferably, 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.

[0033] Preferably, the foil material includes any one of aluminum foil, titanium foil or composite aluminum foil, or a combination of at least two of them.

[0034] This application avoids the use of SBR water-resistant binder and prepares the binder by modifying the acrylic resin. The generated alkoxy group ensures hydrophobicity; the conductive carbon material is modified with silane to prepare the slurry and carbon-coated current collector. Through the cross-linking reaction of the modified group, the carbon-coated current collector has super water resistance.

[0035] In a second aspect, an embodiment of the present application provides a method for preparing the carbon-coated current collector as described in the first aspect, the preparation method comprising:

[0036] (1) methyl isobutyl ketone, a solvent, isobornyl methacrylate, methyl methacrylate, n-butyl acrylate, hydroxyethyl acrylate, silicone oil, and an initiator are mixed and reacted to obtain the binder; an alcohol solution of fluorosilane is mixed with a carbon material and modified to obtain the modified conductive carbon material;

[0037] (2) mixing the binder obtained in step (1) with the modified conductive carbon material to obtain a modified conductive slurry;

[0038] (3) coating the modified conductive slurry obtained in step (2) on the surface of the foil and drying it to obtain the carbon-coated current collector.

[0039] Preferably, the preparation method specifically comprises:

[0040] (1) Under nitrogen conditions, methyl isobutyl ketone, solvent, isobornyl methacrylate, methyl methacrylate, n-butyl acrylate, hydroxyethyl acrylate, silicone oil, and part of the initiator are mixed, and the mixture is kept warm for the first time. The remaining initiator is added and mixed, and the mixture is kept warm for the second time. After cooling, the adhesive is obtained;

[0041] Under acidic conditions, the alcohol solution of fluorosilane is mixed with the carbon material and modified, centrifuged, washed, and vacuum-dried to obtain the modified conductive carbon material;

[0042] (2) mixing the binder obtained in step (1) with the modified conductive carbon material to obtain a modified conductive slurry;

[0043] (3) coating the modified conductive slurry obtained in step (2) on the surface of the foil and drying it to obtain the carbon-coated current collector.

[0044] Preferably, the temperature of the first insulation in step (1) is 75-85°C, for example, it can be 75°C, 80°C, 85°C, 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.

[0045] Preferably, the first insulation time is 1-3h, for example, it can be 1h, 1.5h, 2h, 3h, 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.

[0046] Preferably, the temperature of the second insulation is 75-85°C, for example, it can be 75°C, 80°C, 85°C, 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.

[0047] Preferably, the second insulation time is 2-4h, for example, it can be 2h, 2.5h, 3h, 4h, 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.

[0048] Preferably, the modification temperature is 40-60°C, for example, 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 brevity, this application no longer exhaustively lists the specific points included in the range.

[0049] Preferably, the modification time is 4-6 hours, for example, it can be 4 hours, 4.5 hours, 5 hours, 6 hours, 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.

[0050] Preferably, the washing comprises an ethanol wash.

[0051] Preferably, the vacuum drying temperature is 50-60°C, for example, it can be 50°C, 55°C, 60°C, 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.

[0052] Preferably, the vacuum drying time is 20-30h, for example, it can be 20h, 22h, 25h, 30h, 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.

[0053] Preferably, the mixing in step (2) is carried out under stirring.

[0054] Preferably, the stirring rate is 10-5000 rpm, for example, it can be 10 rpm, 50 rpm, 100 rpm, 1000 rpm, 2000 rpm, 4000 rpm, 5000 rpm, 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.

[0055] Preferably, the mixing temperature is 15-30°C, for example, it can be 15°C, 20°C, 25°C, 30°C, 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.

[0056] Preferably, the mixing time is 95-240 min, for example, it can be 95 min, 100 min, 120 min, 140 min, 160 min, 180 min, 200 min, 220 min, 240 min, 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.

[0057] Preferably, the mixed material in step (2) further includes a wetting agent and a solvent.

[0058] Preferably, the coating comprises dispersing using a homogenizer bar.

[0059] Preferably, the coating rate is 60-120 m / min, for example, it can be 60 m / min, 80 m / min, 100 m / min, 120 m / min, 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.

[0060] Preferably, the drying temperature is 80-120°C, for example, it can be 80°C, 90°C, 100°C, 120°C, 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.

[0061] Preferably, the drying time is 30-60 min, for example, it can be 30 min, 35 min, 40 min, 50 min, 55 min, 60 min, 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.

[0062] In a preferred technical solution, the specific preparation method of the carbon-coated current collector includes the following steps:

[0063] The preparation method of the adhesive comprises: sequentially adding methyl isobutyl ketone and a toluene solution into a three-necked flask equipped with a stirrer, a condenser and a nitrogen connecting tube, heating the flask to 75-85° C., sequentially adding isobornyl methacrylate monomer, methyl methacrylate monomer, n-butyl acrylate monomer, hydroxyethyl acrylate monomer and silicone oil (triisopropoxyvinylsilane), adding 18% of the mixed mass of an initiator azobisisobutyronitrile solution (the volume ratio of the initiator to the solvent is 1:35-40), keeping the mixture at 75-85° C. for 1-3 hours, then adding 9% of the mixed mass of an initiator azobisisobutyronitrile solution (the volume ratio of the initiator to the solvent is 1:35-40), keeping the mixture at 75-85° C. for 2-4 hours, and cooling the mixture to obtain the adhesive.

[0064] The preparation method of the modified conductive carbon material includes: adjusting water to a pH value of 4-5 with acetic acid, then adding an anhydrous ethanol solution containing 1-3% fluorosilane, stirring for 8-12 minutes, adding carbon material, stirring at high speed at 40-60°C for 4-6 hours, then centrifuging, washing 1-3 times with an ethanol-water solution with a volume ratio of 1:(1-2), and finally washing 1-3 times with anhydrous ethanol, and drying in a vacuum oven at 50-60°C for 20-30 hours to obtain the modified conductive carbon material.

[0065] The preparation method of the carbon-coated current collector comprises:

[0066] (1) Prepare a binder aqueous solution according to the formula, add the binder to the remaining solvent water, and stir at a low speed;

[0067] (2) adding the modified conductive carbon material to the binder aqueous solution in the previous step in equal portions to obtain a conductive carbon aqueous solution;

[0068] (3) slowly adding a wetting agent to the conductive carbon aqueous solution in the previous step to obtain a mixed solution;

[0069] (4) homogenizing or sand-milling the mixed solution in the previous step to obtain a dispersed mixed solution;

[0070] (5) The dispersed mixed solution in the previous step is subjected to vacuum treatment to obtain a modified conductive paste.

[0071] (6) 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 super water-resistant carbon-coated current collector.

[0072] In the above step (1), the binder aqueous solution is stirred in a double planetary mixer at a speed of 10 to 30 rpm, a dispersion speed of 2000 to 4000 rpm, a temperature of 15 to 30° C., and a time of 15 to 30 min.

[0073] In the above step (2), the modified conductive material is stirred in a dual planetary mixer at a speed of 40 to 80 rpm, a dispersion speed of 3000 to 6000 rpm, a temperature of 15 to 30° C., and a time of 30 to 90 min.

[0074] In the above step (3), the wetting agent is stirred in a double planetary mixer at a speed of 40 to 80 rpm, a dispersion speed of 3000 to 6000 rpm, a temperature of 15 to 30° C., and a time of 20 to 60 min.

[0075] The particle size processing in the above step (4) can be achieved by a grinder or a homogenizer. In the following specific embodiments, the particle size processing in this application is achieved by a homogenizer, but it is not limited to the homogenizer equipment in the embodiments of this application.

[0076] The dispersed mixed solution in the above step (4) has a D50 of <1.2 μm and a D90 of <5 μm.

[0077] In the above step (5), the mixed slurry is stirred in a double planetary mixer at a reverse stirring speed of 10±2 rpm, a vacuum degree of <-0.07 KPa, a temperature of 15-30° C., and a time of 30-60 min.

[0078] In the above step (6), the modified conductive slurry is coated in a coating machine, and the foil is first subjected to corona treatment or a preheating oven or both 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 and the preheating oven temperature is 85-120°C.

[0079] In the above step (6), the modified conductive paste is coated in a coating machine at a coating speed of 60 to 120 m / min and a drying temperature of 80 to 120°C.

[0080] In a third aspect, an embodiment of the present application provides an application of the carbon-coated current collector as described in the first aspect in a lithium-ion battery or a sodium-ion battery.

[0081] Compared with the related art, the embodiments of the present application have the following beneficial effects:

[0082] The carbon-coated current collector provided in the embodiment of the present application is synthesized by reacting isobornyl methacrylate, methyl methacrylate, n-butyl acrylate, hydroxyethyl acrylate with silicone oil to synthesize a modified acrylic resin. When used as a binder, due to the introduction of silicone oil, it contains alkoxy hydrolysis substituents, which makes it have certain water resistance; fluorosilane is introduced, and fluorosilane contains fluorinated hydrocarbons, which can induce hydrophobicity and also contains alkoxy hydrolysis substituents. The modified conductive carbon material and the binder can form silanol through the hydrolysis reaction of their respective alkoxy groups, and then form new hydrogen bonds with the OH groups, while forming covalent bonds on the surface of the carbon material, forming a highly cross-linked network structure, further enhancing water resistance. The water-resistant wipe can reach more than 200 times, up to 218-232 times.

[0083] Still other aspects will become apparent upon reading and understanding the detailed description. DETAILED DESCRIPTION

[0084] 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.

[0085] The experimental materials used in the examples and comparative examples of this application are as follows:

[0086] (1) Carbon material SPLi, brand SUPER P LI, manufacturer IMERYS;

[0087] (2) Conductive graphite SK6, brand TIMREX KS 6, manufacturer IMERYS;

[0088] (3) Polyethylene glycol, brand PEG400, manufacturer Nantong Hengst;

[0089] (4) Vinyl silicone oil: triisopropoxyvinylsilane, brand JS2891, manufacturer Hubei Jusheng;

[0090] (5) Heptafluorodecyltrimethoxysilane, manufactured by Hubei Jusheng;

[0091] (6) Methyl silicone oil: polydimethylsiloxane, brand YX168, manufacturer Yixin Chemical;

[0092] Example 1

[0093] This embodiment provides a carbon-coated current collector and a preparation method thereof, wherein the carbon-coated current collector includes a foil and a conductive coating provided on the surface of the foil, wherein the conductive coating includes a combination of a modified conductive carbon material and a binder; the raw materials for preparing the binder include, by weight: 50g methyl isobutyl ketone, 28g toluene solution, 24g isobornyl methacrylate, 24g methyl methacrylate, 24g n-butyl acrylate, 24g hydroxyethyl acrylate, 20g silicone oil (triisopropoxyvinylsilane), and 52.5g azobisisobutyronitrile.

[0094] The modified conductive carbon material is a fluorosilane-modified carbon material SPLi, and the mass ratio of fluorosilane heptadecafluorodecyltrimethoxysilane to the carbon material SPLi is 2:10.

[0095] The raw materials for preparing the conductive coating include, by weight, 5g of modified conductive carbon material, 7g of binder, 15g of wetting agent (isopropyl alcohol), and 73g of solvent water;

[0096] The preparation method of the adhesive comprises the following steps: sequentially adding methyl isobutyl ketone and a toluene solution into a three-necked flask equipped with a stirrer, a condenser and a nitrogen connecting tube; heating the flask to 80° C.; sequentially adding isobornyl methacrylate monomer, methyl methacrylate monomer, n-butyl acrylate monomer, hydroxyethyl acrylate monomer and silicone oil (triisopropoxyvinylsilane); adding 18% of the mixed mass of the initiator azobisisobutyronitrile solution (the ratio of initiator to solvent is 1:37); keeping the mixture warm for 2 hours; then adding 9% of the mixed mass of the initiator azobisisobutyronitrile solution (the ratio of initiator to solvent is 1:37); keeping the mixture warm for 3 hours; and cooling the mixture to obtain an adhesive having a solid content of 44±2%.

[0097] The modified conductive carbon material is prepared by adjusting water to a pH of 4 to 5 with acetic acid, then adding an anhydrous ethanol solution containing 2% fluorosilane, stirring for 10 minutes, adding the carbon material SPLi, stirring at high speed at 50°C for 5 hours, then centrifuging, washing twice with a 1:1 ethanol-water solution, and finally washing once with anhydrous ethanol, placing in a vacuum oven and drying at 55°C for 24 hours to obtain the modified conductive carbon material.

[0098] The preparation method of the carbon-coated current collector is as follows:

[0099] (1) Prepare the binder aqueous solution according to the formula and add the binder to the remaining solvent water. The stirring speed of the double planetary mixer is 15 rpm, the dispersion speed is 2000 rpm, the temperature is 25±5℃, and the time is 15 min.

[0100] (2) adding the modified conductive carbon material to the binder aqueous solution in step (1) in two equal portions, with a stirring speed of 60 rpm, a dispersion speed of 4000 rpm, a temperature of 25±5°C, and each time for 15 min to obtain a conductive carbon aqueous solution;

[0101] (3) slowly adding the wetting agent isopropyl alcohol 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;

[0102] (4) homogenizing or sand-milling the mixed solution in step (3) to obtain a dispersed mixed solution with a D50 of 0.886 μm and a D90 of 4.34 μm;

[0103] (5) The mixed slurry in step (4) was subjected to vacuum treatment, with the reverse stirring speed of the double planetary mixer being 10 rpm, the vacuum degree being <-0.07 KPa, the temperature being 25±5°C, and the time being 30 min to obtain a modified conductive slurry.

[0104] (6) The modified conductive paste in step (5) is coated on a double-sided smooth aluminum foil through a coating machine. The aluminum foil is pretreated with a corona machine. The coating speed is 60m / min, the oven temperature is 80°C, and the time is 40min. After drying, the carbon-coated current collector is rolled up.

[0105] Example 2

[0106] This embodiment provides a carbon-coated current collector and a preparation method thereof, wherein the carbon-coated current collector includes a foil and a conductive coating provided on the surface of the foil, wherein the conductive coating includes a combination of a modified conductive carbon material and a binder; the raw materials for preparing the binder include, by weight: 50g methyl isobutyl ketone, 24g toluene solution, 24g isobornyl methacrylate, 24g methyl methacrylate, 24g n-butyl acrylate, 24g hydroxyethyl acrylate, 20g silicone oil (triisopropoxyvinylsilane), and 52.5g azobisisobutyronitrile.

[0107] The modified conductive carbon material is a fluorosilane-modified carbon material (the mass ratio of SP-Li and conductive graphite SK6 is 8:2), and the mass ratio of fluorosilane heptadecafluorodecyltrimethoxysilane to carbon material is 2:10.

[0108] The raw materials for preparing the conductive coating include, by weight, 8g of modified conductive carbon material, 7g of binder, 15g of wetting agent (isopropyl alcohol), and 70g of solvent water;

[0109] The preparation method of the adhesive comprises the following steps: sequentially adding methyl isobutyl ketone and a toluene solution into a three-necked flask equipped with a stirrer, a condenser and a nitrogen connecting tube; heating the flask to 80° C.; sequentially adding isobornyl methacrylate monomer, methyl methacrylate monomer, n-butyl acrylate monomer, hydroxyethyl acrylate monomer and silicone oil (triisopropoxyvinylsilane); adding 18% of the mixed mass of the initiator azobisisobutyronitrile solution (the ratio of initiator to solvent is 1:37); keeping the mixture warm for 2 hours; then adding 9% of the mixed mass of the initiator azobisisobutyronitrile solution (the ratio of initiator to solvent is 1:37); keeping the mixture warm for 3 hours; and cooling the mixture to obtain an adhesive having a solid content of 44±2%.

[0110] The modified conductive carbon material is prepared by adjusting water to a pH of 4-5 with acetic acid, then adding an anhydrous ethanol solution containing 2% fluorosilane, stirring for 10 minutes, adding the carbon material SPLi, and stirring at high speed at 50°C for 5 hours. The mixture is then centrifuged, washed twice with a 1:1 ethanol-water solution, and finally washed once with anhydrous ethanol, and dried in a vacuum oven at 55°C for 24 hours. This yields the modified conductive carbon material.

[0111] The preparation method of the carbon-coated current collector is as follows:

[0112] (1) Prepare the binder aqueous solution according to the formula and add the binder to the remaining solvent water. The stirring speed of the double planetary mixer is 15 rpm, the dispersion speed is 2000 rpm, the temperature is 25±5℃, and the time is 15 min.

[0113] (2) adding the modified conductive carbon material to the binder aqueous solution in step (1) in two equal portions, with a stirring speed of 60 rpm, a dispersion speed of 4000 rpm, a temperature of 25±5°C, and each time for 15 min to obtain a conductive carbon aqueous solution;

[0114] (3) slowly adding the wetting agent isopropyl alcohol 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;

[0115] (4) homogenizing or sand-milling the mixed solution in step (3) to obtain a dispersed mixed solution with a D50 of 0.912 μm and a D90 of 4.12 μm;

[0116] (5) The mixed slurry in step (4) was subjected to vacuum treatment, with the reverse stirring speed of the double planetary mixer being 10 rpm, the vacuum degree being <-0.07 KPa, the temperature being 25±5°C, and the time being 30 min to obtain a modified conductive slurry.

[0117] (6) The modified conductive paste in step (5) is coated on a double-sided smooth aluminum foil by a coating machine. The aluminum foil is pretreated by a corona machine. The coating speed is 80m / min, the oven temperature is 100°C, and the time is 30min. After drying, the carbon-coated current collector is rolled up.

[0118] Example 3

[0119] This embodiment provides a carbon-coated current collector and a preparation method thereof, wherein the carbon-coated current collector includes a foil and a conductive coating provided on the surface of the foil, wherein the conductive coating includes a combination of a modified conductive carbon material and a binder; the raw materials for preparing the binder include, by weight: 50g methyl isobutyl ketone, 28g toluene solution, 24g isobornyl methacrylate, 24g methyl methacrylate, 24g n-butyl acrylate, 24g hydroxyethyl acrylate, 20g silicone oil (triisopropoxyvinylsilane), and 52.5g azobisisobutyronitrile.

[0120] The modified conductive carbon material is a fluorosilane-modified carbon material (the mass ratio of SP-Li and conductive graphite SK6 is 8:2), and the mass ratio of fluorosilane heptadecafluorodecyltrimethoxysilane to carbon material is 2:10.

[0121] The raw materials for preparing the conductive coating include, by weight: 6g of modified conductive carbon material, 10g of binder, 10g of wetting agent (isopropyl alcohol), and 74g of solvent water;

[0122] The preparation method of the adhesive comprises the following steps: sequentially adding methyl isobutyl ketone and a toluene solution into a three-necked flask equipped with a stirrer, a condenser and a nitrogen connecting tube; heating the flask to 80° C.; sequentially adding isobornyl methacrylate monomer, methyl methacrylate monomer, n-butyl acrylate monomer, hydroxyethyl acrylate monomer and silicone oil (triisopropoxyvinylsilane); adding 18% of the mixed mass of the initiator azobisisobutyronitrile solution (the ratio of initiator to solvent is 1:37); keeping the mixture warm for 2 hours; then adding 9% of the mixed mass of the initiator azobisisobutyronitrile solution (the ratio of initiator to solvent is 1:37); keeping the mixture warm for 3 hours; and cooling the mixture to obtain an adhesive having a solid content of 44±2%.

[0123] The modified conductive carbon material preparation method includes adjusting water to a pH of 4-5 with acetic acid, then adding an anhydrous ethanol solution containing 2% fluorosilane, stirring for 10 minutes, adding carbon material SPLi and conductive graphite SK6, stirring at high speed at 50°C for 5 hours, then centrifuging, washing twice with a 1:1 ethanol-water solution, and finally washing once with anhydrous ethanol, and drying in a vacuum oven at 55°C for 24 hours. This yields the modified conductive carbon material.

[0124] The preparation method of the carbon-coated current collector is as follows:

[0125] (1) Prepare the binder aqueous solution according to the formula and add the binder to the remaining solvent water. The stirring speed of the double planetary mixer is 15 rpm, the dispersion speed is 2000 rpm, the temperature is 25±5℃, and the time is 15 min.

[0126] (2) adding the modified conductive carbon material to the binder aqueous solution in step (1) in two equal portions, with a stirring speed of 60 rpm, a dispersion speed of 4000 rpm, a temperature of 25±5°C, and each time for 15 min to obtain a conductive carbon aqueous solution;

[0127] (3) slowly adding the wetting agent isopropyl alcohol 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;

[0128] (4) homogenizing or sand-milling the mixed solution in step (3) to obtain a dispersed mixed solution with a D50 of 0.912 μm and a D90 of 4.12 μm;

[0129] (5) The mixed slurry in step (4) was subjected to vacuum treatment, with the reverse stirring speed of the double planetary mixer being 10 rpm, the vacuum degree being <-0.07 KPa, the temperature being 25±5°C, and the time being 30 min to obtain a modified conductive slurry.

[0130] (6) The modified conductive paste in step (5) is coated on a double-sided smooth aluminum foil through a coating machine. The aluminum foil is pretreated with a corona machine. The coating speed is 100 m / min, the oven temperature is 120°C, and the time is 30 min. After drying, the carbon-coated current collector is rolled up.

[0131] Example 4

[0132] This embodiment provides a carbon-coated current collector and a preparation method thereof, wherein the carbon-coated current collector includes a foil and a conductive coating disposed on the surface of the foil, wherein the conductive coating includes a combination of a modified conductive carbon material and a binder; the raw materials for preparing the binder include, by weight: 60g methyl isobutyl ketone, 30g toluene solution, 25g isobornyl methacrylate, 25g methyl methacrylate, 25g n-butyl acrylate, 25g hydroxyethyl acrylate, 22g silicone oil polydimethylsiloxane, and 55g azobisisobutyronitrile.

[0133] The modified conductive carbon material is a fluorosilane-modified carbon material (the mass ratio of SP-Li and conductive graphite SK6 is 8:2), and the mass ratio of fluorosilane heptadecafluorodecyltrimethoxysilane to carbon material is 1:6.

[0134] The raw materials for preparing the conductive coating include, by weight: 6g of modified conductive carbon material, 10g of binder, 10g of wetting agent (isopropyl alcohol), and 74g of solvent water;

[0135] The preparation method of the adhesive comprises the following steps: sequentially adding methyl isobutyl ketone and a toluene solution into a three-necked flask equipped with a stirrer, a condenser and a nitrogen connecting tube; heating the flask to 80° C.; sequentially adding isobornyl methacrylate monomer, methyl methacrylate monomer, n-butyl acrylate monomer, hydroxyethyl acrylate monomer and silicone oil (polydimethylsiloxane); adding 18% of the mixed mass of the initiator azobisisobutyronitrile solution (the ratio of initiator to solvent is 1:37); keeping the mixture warm for 2 hours; then adding 9% of the mixed mass of the initiator azobisisobutyronitrile solution (the ratio of initiator to solvent is 1:37); keeping the mixture warm for 3 hours; and cooling the mixture to obtain an adhesive with a solid content of 44±2%.

[0136] The modified conductive carbon material preparation method includes adjusting water to a pH of 4-5 with acetic acid, then adding an anhydrous ethanol solution containing 2% fluorosilane, stirring for 10 minutes, adding carbon material SPLi and conductive graphite SK6, stirring at high speed at 50°C for 5 hours, then centrifuging, washing twice with a 1:1 ethanol-water solution, and finally washing once with anhydrous ethanol, and drying in a vacuum oven at 55°C for 24 hours. This yields the modified conductive carbon material.

[0137] The preparation method of the carbon-coated current collector is as follows:

[0138] (1) Prepare the binder aqueous solution according to the formula and add the binder to the remaining solvent water. The stirring speed of the double planetary mixer is 15 rpm, the dispersion speed is 2000 rpm, the temperature is 25±5℃, and the time is 15 min.

[0139] (2) adding the modified conductive carbon material to the binder aqueous solution in step (1) in two equal portions, with a stirring speed of 60 rpm, a dispersion speed of 4000 rpm, a temperature of 25±5°C, and each time for 15 min to obtain a conductive carbon aqueous solution;

[0140] (3) slowly adding the wetting agent isopropyl alcohol 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;

[0141] (4) homogenizing or sand-milling the mixed solution in step (3) to obtain a dispersed mixed solution with a D50 of 0.912 μm and a D90 of 4.12 μm;

[0142] (5) The mixed slurry in step (4) was subjected to vacuum treatment, with the reverse stirring speed of the double planetary mixer being 10 rpm, the vacuum degree being <-0.07 KPa, the temperature being 25±5°C, and the time being 30 min to obtain a modified conductive slurry.

[0143] (6) The modified conductive paste in step (5) is coated on a double-sided smooth aluminum foil through a coating machine. The aluminum foil is pretreated with a corona machine. The coating speed is 100 m / min, the oven temperature is 120°C, and the time is 30 min. After drying, the carbon-coated current collector is rolled up.

[0144] Example 5

[0145] This embodiment provides a carbon-coated current collector and a preparation method thereof, wherein the carbon-coated current collector includes a foil and a conductive coating disposed on the surface of the foil, wherein the conductive coating includes a combination of a modified conductive carbon material and a binder; the raw materials for preparing the binder include, by weight: 50g methyl isobutyl ketone, 28g toluene solution, 24g isobornyl methacrylate, 24g methyl methacrylate, 24g n-butyl acrylate, 24g hydroxyethyl acrylate, 20g silicone oil (polydimethylsiloxane), and 52.5g azobisisobutyronitrile.

[0146] The modified conductive carbon material is a fluorosilane-modified carbon material (the mass ratio of SP-Li and conductive graphite SK6 is 8:2), and the mass ratio of fluorosilane heptadecafluorodecyltrimethoxysilane to carbon material is 2:10.

[0147] The raw materials for preparing the conductive coating include, by weight: 6g of modified conductive carbon material, 10g of binder, 10g of wetting agent polyethylene glycol, and 74g of solvent water;

[0148] The preparation method of the adhesive comprises the following steps: sequentially adding methyl isobutyl ketone and a toluene solution into a three-necked flask equipped with a stirrer, a condenser and a nitrogen connecting tube; heating the flask to 85° C.; sequentially adding isobornyl methacrylate monomer, methyl methacrylate monomer, n-butyl acrylate monomer, hydroxyethyl acrylate monomer and silicone oil (polydimethylsiloxane); adding 18% of the mixed mass of the initiator azobisisobutyronitrile solution (the ratio of initiator to solvent is 1:37); keeping the mixture warm for 3 hours; then adding 9% of the mixed mass of the initiator azobisisobutyronitrile solution (the ratio of initiator to solvent is 1:37); keeping the mixture warm for 4 hours; and cooling the mixture to obtain an adhesive having a solid content of 44±2%.

[0149] The modified conductive carbon material preparation method includes adjusting water to a pH of 4-5 with acetic acid, then adding an anhydrous ethanol solution containing 2% fluorosilane, stirring for 10 minutes, adding carbon material SPLi and conductive graphite SK6, stirring at high speed at 50°C for 5 hours, then centrifuging, washing twice with a 1:1 ethanol-water solution, and finally washing once with anhydrous ethanol, and drying in a vacuum oven at 60°C for 30 hours. This yields the modified conductive carbon material.

[0150] The preparation method of the carbon-coated current collector is as follows:

[0151] (1) Prepare the binder aqueous solution according to the formula and add the binder to the remaining solvent water. The stirring speed of the double planetary mixer is 15 rpm, the dispersion speed is 2000 rpm, the temperature is 25±5℃, and the time is 15 min.

[0152] (2) adding the modified conductive carbon material to the binder aqueous solution in step (1) in two equal portions, with a stirring speed of 60 rpm, a dispersion speed of 4000 rpm, a temperature of 25±5°C, and each time for 15 min to obtain a conductive carbon aqueous solution;

[0153] (3) slowly adding the wetting agent isopropyl alcohol 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;

[0154] (4) homogenizing or sand-milling the mixed solution in step (3) to obtain a dispersed mixed solution with a D50 of 0.912 μm and a D90 of 4.12 μm;

[0155] (5) The mixed slurry in step (4) was subjected to vacuum treatment, with the reverse stirring speed of the double planetary mixer being 10 rpm, the vacuum degree being <-0.07 KPa, the temperature being 25±5°C, and the time being 30 min to obtain a modified conductive slurry.

[0156] (6) The modified conductive paste in step (5) is coated on a double-sided smooth aluminum foil through a coating machine. The aluminum foil is pretreated with a corona machine. The coating speed is 100 m / min, the oven temperature is 80°C, and the time is 60 min. After drying, the carbon-coated current collector is rolled up.

[0157] Comparative Example 1

[0158] This comparative example provides a carbon-coated current collector and a preparation method thereof. The raw materials for preparing the carbon-coated current collector include, by weight: 5g of conductive material SP-Li, 12.8g of binder acrylic polymer, 0.1g of additive sodium hydroxide, 15g of wetting agent, and 67.1g of solvent;

[0159] The preparation method of the carbon-coated current collector is as follows:

[0160] Add them in sequence, stir and disperse them separately, and after homogenization, D50 = 0.899 μm, D90 = 4.21 μm, and vacuum treat for 30 minutes (vacuum degree is <-0.07 KPa) to obtain a conductive slurry (solid content is 8.3%, slurry pH is 6.2), which is coated on double-sided smooth aluminum foil by a coater. The aluminum foil is pretreated by a 6KW corona machine, the coating speed is 60 m / min, and the oven temperature is 80°C. After drying, it is rolled up to obtain a carbon-coated current collector.

[0161] Comparative Example 2

[0162] This comparative example provides a carbon-coated current collector and a preparation method thereof. The raw materials for preparing the carbon-coated current collector include, by weight: 8 g of conductive material, namely, SP-Li and conductive graphite SK6 (the mass ratio of SP-Li to conductive graphite SK6 is 8:2), 12.8 g of binder acrylic polymer, 0.1 g of additive sodium hydroxide, 15 g of wetting agent, and 64.1 g of solvent;

[0163] The preparation method of the carbon-coated current collector is as follows:

[0164] Add them in sequence, stir and disperse them separately, and after homogenization, D50 = 0.941 μm, D90 = 4.78 μm, and vacuum treat for 30 minutes (vacuum degree is <-0.07 KPa) to obtain a conductive slurry (solid content is 10.9%, slurry pH is 6.5), which is coated on double-sided smooth aluminum foil by a coater. The aluminum foil is pretreated with a 6KW corona machine, the coating speed is 80 m / min, and the oven temperature is 100°C and then rolled up to obtain a carbon-coated current collector.

[0165] Comparative Example 3

[0166] This comparative example provides a carbon-coated current collector and a preparation method thereof. The raw materials for preparing the carbon-coated current collector include, by weight: 6 g of conductive material, namely, SP-Li and conductive graphite SK6 (the mass ratio of SP-Li to conductive graphite SK6 is 8:2), 13.5 g of binder acrylic polymer, 0.1 g of additive sodium hydroxide, 20 g of wetting agent, and 60.4 g of solvent;

[0167] The preparation method of the carbon-coated current collector is as follows:

[0168] Add them in sequence, stir and disperse them separately, and after homogenization, D50 = 1.193 μm, D90 = 4.86 μm, and vacuum treat for 30 minutes (vacuum degree is <-0.07 KPa) to obtain a conductive slurry (solid content is 10.45%, slurry pH is 6.9), which is coated on double-sided smooth aluminum foil by a coater. The aluminum foil is pretreated with a 6KW corona machine, the coating speed is 100 m / min, and the oven temperature is 120°C. After drying, it is rolled up to obtain a carbon-coated current collector.

[0169] Comparative Example 4

[0170] This comparative example provides a carbon-coated current collector and a preparation method thereof. The raw materials for preparing the carbon-coated current collector include, by weight, 5g of modified conductive carbon material, 12.8g of binder acrylic polymer, 0.1g of additive sodium hydroxide, 15g of wetting agent, and 67.1g of solvent water;

[0171] The modified conductive carbon material is a fluorosilane-modified carbon material SPLi, and the mass ratio of fluorosilane heptadecafluorodecyltrimethoxysilane to the carbon material SPLi is 2:10.

[0172] The modified conductive carbon material is prepared by adjusting water to a pH of 4 to 5 with acetic acid, then adding an anhydrous ethanol solution containing 2% fluorosilane, stirring for 10 minutes, adding the carbon material SPLi, stirring at high speed at 50°C for 5 hours, then centrifuging, washing twice with a 1:1 ethanol-water solution, and finally washing once with anhydrous ethanol, placing in a vacuum oven and drying at 55°C for 24 hours to obtain the modified conductive carbon material.

[0173] The preparation method of the carbon-coated current collector is as follows:

[0174] Add them in sequence, stir and disperse them separately, and after homogenization, D50 = 0.899 μm, D90 = 4.21 μm, and vacuum treat for 30 minutes (vacuum degree is <-0.07 KPa) to obtain a conductive slurry (solid content is 8.3%, slurry pH is 6.2), which is coated on double-sided smooth aluminum foil by a coater. The aluminum foil is pretreated by a 6KW corona machine, the coating speed is 60 m / min, and the oven temperature is 80°C. After drying, it is rolled up to obtain a carbon-coated current collector.

[0175] Comparative Example 5

[0176] This comparative example provides a carbon-coated current collector and a preparation method thereof. The raw materials for preparing the carbon-coated current collector include, by weight: 8g of conductive material, namely, SP-Li and conductive graphite SK6 (the mass ratio of SP-Li to conductive graphite SK6 is 8:2), 7g of binder, 15g of wetting agent, and 70g of solvent water;

[0177] The preparation method of the adhesive comprises the following steps: sequentially adding methyl isobutyl ketone and a toluene solution into a three-necked flask equipped with a stirrer, a condenser and a nitrogen connecting tube; heating the flask to 80° C.; sequentially adding isobornyl methacrylate monomer, methyl methacrylate monomer, n-butyl acrylate monomer, hydroxyethyl acrylate monomer and silicone oil (triisopropoxyvinylsilane); adding 18% of the mixed mass of the initiator azobisisobutyronitrile solution (the ratio of initiator to solvent is 1:37); keeping the mixture warm for 2 hours; then adding 9% of the mixed mass of the initiator azobisisobutyronitrile solution (the ratio of initiator to solvent is 1:37); keeping the mixture warm for 3 hours; and cooling the mixture to obtain an adhesive having a solid content of 44±2%.

[0178] The preparation method of the carbon-coated current collector is as follows:

[0179] Add them in sequence, stir and disperse them separately, and after homogenization, D50 = 0.941 μm, D90 = 4.78 μm, and vacuum treat for 30 minutes (vacuum degree is <-0.07 KPa) to obtain a conductive slurry (solid content is 10.9%, slurry pH is 6.5), which is coated on double-sided smooth aluminum foil by a coater. The aluminum foil is pretreated with a 6KW corona machine, the coating speed is 80 m / min, and the oven temperature is 100°C and then rolled up to obtain a carbon-coated current collector.

[0180] The performance of the carbon-coated current collectors obtained in Examples 1-5 and Comparative Examples 1-5 was tested using the following method:

[0181] (1) Surface resistance (place a 10 cm*10 cm sample flat and test it with a four-probe resistance tester);

[0182] (2) 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 make the cotton swab wipe the coated surface of the carbon-coated foil, observe whether the coating changes color and falls off, and record the number of wipes);

[0183] The various properties of the carbon-coated current collectors obtained in Examples 1-5 and Comparative Examples 1-5 were tested according to the above-mentioned performance testing method. The test results are shown in Table 1.

[0184] Table 1

[0185] From the data in Table 1, it can be seen that the embodiment has obvious water resistance, and the number of water resistance times can reach more than 200 times; from Comparative Examples 4 and 5, it can be seen that the use of modified conductive carbon material and silicone acrylic resin binder alone has certain water resistance compared with Comparative Examples 1-5, but compared with the embodiment, the water resistance is too poor, indicating that the modified conductive carbon material and silicone acrylic resin can form silanol through the hydrolysis reaction of their respective alkoxy groups, and then form new hydrogen bonds with the OH group, while forming covalent bonds on the surface of the carbon material, forming a highly cross-linked network structure, and further enhancing the water resistance.

[0186] The applicant declares that this application uses the above-mentioned embodiments to illustrate a carbon-coated current collector, its preparation method, and 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 in 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 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 a modified conductive carbon material and a binder, and the raw materials for preparing the binder include, by weight: 40-60 parts of methyl isobutyl ketone, 25-30 parts of solvent, 20-25 parts of isobornyl methacrylate, 20-25 parts of methyl methacrylate, 20-25 parts of n-butyl acrylate, 20-25 parts of hydroxyethyl acrylate, 18-22 parts of silicone oil, and 50-55 parts of initiator; the modified conductive carbon material is a fluorosilane-modified carbon material.

2. The carbon-coated current collector according to claim 1, wherein: The solvent includes toluene.

3. The carbon-coated current collector according to claim 1 or 2, wherein: The initiator includes azobisisobutyronitrile.

4. The carbon-coated current collector according to any one of claims 1 to 3, wherein: The silicone oil includes any one of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methylphenyl silicone oil, methylethoxy silicone oil, methyltrifluoropropyl silicone oil, methylvinyl silicone oil, methylhydroxy silicone oil, ethyl hydrogen silicone oil or hydroxy hydrogen silicone oil, or a combination of at least two thereof.

5. The carbon-coated current collector according to any one of claims 1 to 4, wherein: The fluorosilane includes heptadecafluorodecyltrimethoxysilane; Preferably, the mass ratio of the fluorosilane to the carbon material is 1:(4-6).

6. The carbon-coated current collector according to any one of claims 1 to 5, wherein: The modified conductive coating material comprises, by weight: 5-10 parts of modified conductive carbon material, 7-22 parts of binder, and 3-20 parts of wetting agent; Preferably, the carbon material comprises any one of conductive carbon black, conductive graphite, carbon nanotubes, carbon nanofibers or graphene, or a combination of at least two thereof; Preferably, 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.

7. The carbon-coated current collector according to any one of claims 1 to 6, 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.

8. A method for preparing a carbon-coated current collector according to any one of claims 1 to 7, comprising: (1) methyl isobutyl ketone, a solvent, isobornyl methacrylate, methyl methacrylate, n-butyl acrylate, hydroxyethyl acrylate, silicone oil, and an initiator are mixed and reacted to obtain the binder; an alcohol solution of fluorosilane is mixed with a carbon material and modified to obtain the modified conductive carbon material; (2) mixing the binder obtained in step (1) with the modified conductive carbon material to obtain a modified conductive slurry; (3) coating the modified conductive slurry obtained in step (2) on the surface of the foil and drying it to obtain the carbon-coated current collector.

9. The preparation method according to claim 8, wherein: The preparation method specifically comprises: (1) under nitrogen conditions, methyl isobutyl ketone, solvent, isobornyl methacrylate, methyl methacrylate, n-butyl acrylate, hydroxyethyl acrylate, silicone oil, and part of the initiator are mixed, and the mixture is kept warm for the first time. The remaining initiator is added and mixed, and the mixture is kept warm for the second time. After cooling, the adhesive is obtained; Under acidic conditions, the alcohol solution of fluorosilane is mixed with the carbon material and modified, centrifuged, washed, and vacuum dried to obtain the modified conductive carbon material; (2) mixing the binder obtained in step (1) with the modified conductive carbon material to obtain a modified conductive slurry; (3) coating the modified conductive slurry obtained in step (2) on the surface of the foil and drying it to obtain the carbon-coated current collector.

10. The preparation method according to claim 9, wherein: The temperature of the first insulation in step (1) is 75-85° C. Preferably, the first insulation time is 1-3 hours.

11. The preparation method according to claim 9 or 10, wherein: The temperature of the second insulation is 75-85°C; Preferably, the second insulation time is 2-4 hours.

12. The preparation method according to any one of claims 9 to 11, wherein: The modification temperature is 40-60°C; Preferably, the modification time is 4-6h; Preferably, the cleaning comprises ethanol cleaning; Preferably, the vacuum drying temperature is 50-60°C; Preferably, the vacuum drying time is 20-30 hours.

13. The preparation method according to any one of claims 9 to 12, wherein: The mixing in step (2) is carried out under stirring; Preferably, the stirring rate is 10-5000 rpm; Preferably, the mixing temperature is 15-30°C; Preferably, the mixing time is 95-240 min.

14. The preparation method according to any one of claims 9 to 13, wherein: The mixed material in step (2) further includes a wetting agent and a solvent; Preferably, the coating comprises dispersing using a homogenizer bar; Preferably, the coating rate is 60-120 m / min; Preferably, the drying temperature is 80-120°C; Preferably, the drying time is 30 to 60 minutes.

15. Use of the carbon-coated current collector according to any one of claims 1 to 7 in a lithium-ion battery or a sodium-ion battery.

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