CN115799507B

CN115799507B - Natural graphite negative electrode material with surface connected with binder, and preparation method and application thereof

Info

Publication number: CN115799507B
Application number: CN202210907908.5A
Authority: CN
Inventors: 岳敏; 杜宁; 王露琪; 邓清夫
Original assignee: Carbon New Energy Group Co ltd
Current assignee: Carbon New Energy Group Co ltd
Priority date: 2022-07-29
Filing date: 2022-07-29
Publication date: 2024-01-09
Anticipated expiration: 2042-07-29
Also published as: CN115799507A

Abstract

The invention provides a natural graphite anode material with a surface connected with a binder, a preparation method and application thereof, wherein the natural graphite anode material with the surface connected with the binder comprises a natural graphite anode material and the binder with the surface connected with the natural graphite anode material, the binder comprises a first binder and a second binder, the first binder comprises a first polymer, a polymerization monomer of the first polymer comprises any one or a combination of at least two of acrylic ester monomers, acrylamide monomers, acrylonitrile monomers or styrene monomers, and the second binder is bi-component polyacrylate. The natural graphite anode material can improve the expansion aging problem in the circulation process, improve the cohesiveness and improve the comprehensive performance of the material, so that the lithium ion battery containing the natural graphite anode material has high first coulomb efficiency and circulation stability.

Description

Natural graphite negative electrode material with surface connected with binder, and preparation method and application thereof

Technical Field

The invention belongs to the technical field of lithium ion batteries, relates to a natural graphite negative electrode material and a preparation method and application thereof, and particularly relates to a natural graphite negative electrode material with a surface connected with a binder and a preparation method and application thereof.

Background

The lithium ion battery has the advantages of high energy density, small volume, environmental friendliness and the like, and is widely used in the fields of 3C (electronic digital), energy storage, power and the like. It is important to improve the comprehensive performance of lithium ion batteries in industry, including energy density and cycle life. The existing anode materials used in maturity still have some natural problems and defects such as the anode materials of natural graphite and the like, for example, the bonding force between active substances and a current collector is poor, the irreversible expansion problem of the materials caused by cyclic aging, the side reaction of electrolyte, the aging of SEI film and the like, and the problems of active powder fragmentation and the like are brought along, so that the capacity and the cyclic stability of a battery are influenced, and even potential safety hazards of the battery are further caused.

CN113270586a discloses a preparation method and application of an in-situ polymerization coated modified silicon-based negative electrode material, wherein the surface of the silicon-based material is coated with a composite coating layer of inorganic matters and polymers, and the silicon-based negative electrode material enables monomers of the polymers to perform in-situ polymerization reaction on the surface of the silicon-based material through the action of deep eutectic solvents to obtain the composite coating layer of inorganic matters uniformly distributed in the polymers; the inorganic substance is lithium salt, and the thickness of the composite coating layer is 5-15nm. The composite coating layer is formed on the surface of the material by in-situ polymerization of a polymer monomer doped with an inorganic substance. The modified silicon-based anode material improves the first coulombic efficiency of the anode material, but the cycle stability of the battery is still to be further improved.

Accordingly, in the art, it is desirable to develop a material capable of improving the problem of swelling and aging of a negative electrode material during a cycle, and at the same time, improving the adhesion between active materials and a current collector, thereby improving the overall performance.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a natural graphite anode material and a preparation method and application thereof, in particular to a natural graphite anode material with a surface connected with a binder and a preparation method and application thereof.

To achieve the purpose, the invention adopts the following technical scheme:

in one aspect, the invention provides a natural graphite anode material with a surface connected with a binder, the natural graphite anode material with the surface connected with the binder comprises a natural graphite anode material and the binder with the surface connected with the natural graphite anode material, the binder comprises a first binder and a second binder, the first binder comprises a first polymer, a polymerized monomer of the first polymer comprises any one or a combination of at least two of an acrylic monomer, an acrylamide monomer, an acrylonitrile monomer or a styrene monomer, and the second binder is bi-component polyacrylate.

In the invention, the first binder is of a particle structure, the second binder is of a non-particle structure, and the first binder and the second binder form a polymer network on the surface of the natural graphite anode material.

According to the invention, the first binder and the second binder are connected to the surface of the natural graphite anode material, the first binder is an acrylic acid ester particle structural component, the surface of the active substance is in a dot-shaped structure, and the second binder is in a non-particle structure, and the two binders are synergistic, so that a polymer coating structure is formed on the surface of the active substance together, the problem of expansion and ageing of the natural graphite anode material in the circulating process can be solved, and meanwhile, the cohesiveness between anode active substances and a current collector can be improved, so that the comprehensive performance of the material is improved.

Preferably, the acrylic monomer is selected from any one or a combination of at least two of methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, isooctyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, isooctyl methacrylate, hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, sodium acrylate, lithium acrylate, acrylic acid, lithium methacrylate, lithium itaconic acid, lithium monobutyl itaconate or monobutyl itaconate.

Preferably, the acrylamide monomer is selected from any one or a combination of at least two of acrylamide, methacrylamide, N-methylolacrylamide or N, N-dimethylacrylamide.

Preferably, the first binder further comprises cellulose, and the cellulose is mixed and entangled with the first polymer, so that the emulsion dispersion stability during the preparation of the first polymer can be improved.

Preferably, the cellulose is selected from any one or a combination of at least two of cellulose acetate, methylcellulose, ethylcellulose, hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), nitrocellulose, carboxymethyl cellulose (CMC), carboxyethylcellulose, carboxypropylcellulose, carboxyisopropylcellulose, sodium cellulose, sodium nitrocellulose or sodium carboxyalkyl cellulose.

Preferably, the preparation raw materials of the two-component polyacrylate comprise isocyanate monomers and hydroxyl-terminated acrylate polymers.

Preferably, the preparation raw materials of the two-component polyacrylate further comprise a crosslinking agent (or referred to as a chain extender) and/or a catalyst.

Preferably, the isocyanate-based monomer is selected from any one or a combination of at least two of Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), 1, 5-Naphthalene Diisocyanate (NDI), dimethylbiphenyl diisocyanate (TODI), hexamethylene Diisocyanate (HDI), hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, 2, 4-trimethylhexamethylene diisocyanate (TMDI), xylylene Diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), hydrogenated Xylylene Diisocyanate (HXDI), isophorone diisocyanate (IPDI), 4' -dicyclohexylmethane diisocyanate (HMDI), methylcyclohexane diisocyanate (HTDI), 1, 4-cyclohexane diisocyanate, 1, 4-phenylene diisocyanate (PPDI), 1, 3-phenylene diisocyanate or norbornane diisocyanate (NBDI).

In the present invention, the hydroxyl-terminated acrylate polymer used is a liquid hydroxyl-terminated acrylate polymer having a number average molecular weight of preferably 100 to 10000, for example, 100, 150, 200, 300, 500, 700, 800, 900, 1000, 2000, 4000, 5000, 7000, 9000 or 10000, etc.

Preferably, the polymerized monomer of the hydroxyl-terminated acrylate polymer comprises any one or a combination of at least two of styrene (St), acrylic Acid (AA), butyl Acrylate (BA), butyl Methacrylate (BMA), hydroxyethyl methacrylate (HEMA), hydroxyethyl acrylate (HEA), hydroxypropyl methacrylate (HPMA) or hydroxypropyl acrylate (HPA).

Preferably, the cross-linking agent is selected from any one or a combination of at least two of 1, 4-butanediol, ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, glycerol, trimethylolpropane, 3-dichloro-4, 4-diaminodiphenylmethane, 3, 5-dimethylthiotoluenediamine, 3, 5-diethyltoluenediamine, 2, 4-diamino-3, 5-dimethylthiochlorobenzene, isophoronediamine, ethanolamine, diethanolamine, triethanolamine, N-bis (2-hydroxypropyl) aniline, 1, 4-cyclohexanediol, hydrogenated bisphenol A, dimethylenephenyl glycol, hydroquinone bis-beta-hydroxyethyl ether, resorcinol hydroxy ether, glycerol allyl ether, glycidol allyl ether or dicumyl peroxide.

Preferably, the catalyst is selected from any one or a combination of at least two of tertiary amine catalysts or organometallic compounds.

Preferably, the catalyst is selected from any one or a combination of at least two of N, N-dimethylcyclohexylamine, dibutyltin dilaurate, bismuth 2-ethylhexanoate or bismuth neodecanoate.

In the present invention, the glass transition temperature Tg of the polymer of the first binder ranges from-50 to 200 ℃, for example, -50 ℃, -20 ℃, -10 ℃, 0 ℃, 5 ℃, 10 ℃, 20 ℃, 50 ℃, 70 ℃, 90 ℃, 100 ℃, 130 ℃, 150 ℃, 180 ℃ or 200 ℃. Tg is obtained according to differential scanning calorimetry DSC test.

Preferably, the particle size of the first binder is 200nm-10 μm, for example 200nm, 400nm, 500nm, 800nm, 1 μm, 3 μm, 5 μm, 8 μm or 10 μm.

In the present invention, the first binder may be prepared by polymerization by emulsion polymerization or microemulsion polymerization or suspension polymerization or microsuspension polymerization method.

Preferably, the second binder is obtained by in-situ polymerization on the surface of the natural graphite anode material to which the first binder is attached.

According to the invention, the in-situ polymerization is carried out on the surface of the natural graphite anode material connected with the first binder, so that isocyanate monomers and hydroxyl-terminated acrylate polymers are polymerized to obtain the second binder, the second binder is a polymer with better elasticity, the cohesive elasticity is enhanced, the first binder is an acrylate particle structure component, a punctiform structure is formed on the surface of an active substance, the second binder is a non-granular structure, the two binders are synergistic, and a polymer coating structure is formed on the surface of the active substance together, so that the volume expansion problem of the natural graphite anode material in the circulation process can be further relieved, the cohesive property between the natural graphite anode materials and a current collector is further enhanced, and the first coulombic efficiency and the circulation stability of the lithium ion battery are further improved.

In the present invention, cellulose is added to the first binder as a blending material of the first polymer, and the first polymer is mixed and entangled together, so that the suspension stability of the emulsion and the dispersion stability and the binding force of the emulsion when the emulsion and the active material are mixed later can be improved.

In another aspect, the present invention provides a method for preparing the natural graphite anode material with the surface connected with the binder, wherein the preparation method comprises the following steps:

(1) Adding a first binder and a natural graphite anode material into a solvent for wet mixing to obtain mixed slurry, and removing the solvent in the mixed slurry to obtain a solvent-free mixture;

(2) Mixing an isocyanate monomer, a hydroxyl-terminated acrylate polymer, an optional cross-linking agent and an optional catalyst, and then mixing with the solvent-free mixture obtained in the step (1) to perform in-situ polymerization reaction to obtain the natural graphite anode material with the surface connected with the binder.

According to the invention, the first binder is connected to the surface of the natural graphite anode material in a wet mixing mode, the first binder is an acrylic acid ester particle structural component, a dot-shaped structure is formed on the surface of an active substance, then a second binder obtained by polymerizing an isocyanate monomer and a hydroxyl-terminated acrylic acid ester polymer is connected to the surface of the natural graphite anode material through in-situ polymerization, the second binder is a non-particle structure, the second binder is a polymer with better elasticity, the cohesive elasticity is enhanced, the high molecular component and the natural graphite anode material are uniformly mixed in a wet mixing process, the mixing uniformity of the high molecular component and the natural graphite anode material can be ensured, the in-situ polymerized acrylic acid ester polymer component can be well compatible with the particle type polyacrylate component of the first binder, a better polymer network is formed, the network coating and connecting structure of the surface of the natural graphite are realized, the problem that the surface defects of the natural graphite are more is solved, the second binder is directly synthesized on the surface of the natural graphite active substance in-situ, the bonding effect of the binder and the natural graphite active substance is enhanced with hydrogen bond and Van der Waals force between the surface functional groups of the active substance, the bonding effect of the binder and the natural graphite active substance is synergistic effect is enhanced, the bonding effect of the high and the active substance is better in the bonding effect of the surface of the active substance or the spherical active substance after the active substance is completely coated on the surface of the active substance or is synthesized, and the fiber is better in a better bonding state.

Preferably, the preparation method of the first binder in the step (1) includes the following steps:

adding a first polymerization monomer and an initiator into an aqueous solution containing an emulsifier and/or a dispersing agent, and performing a first polymerization reaction to obtain a first binder emulsion, wherein the obtained binder emulsion removes solvent water to obtain a first binder, and the first polymerization monomer comprises any one or a combination of at least two of an acrylic monomer, an acrylamide monomer, an acrylonitrile monomer and a styrene monomer.

Preferably, the total ratio of the dispersant and emulsifier is from 0.1% to 10.0% (e.g., 0.1%, 0.5%, 1.0%, 3.0%, 5.0%, 8.0%, or 10.0%), the ratio of the first polymeric monomer is from 80.0% to 99.8% (e.g., 80.0%, 83.0%, 85.0%, 88.0%, 90.0%, 92.0%, 95.0%, 98.0%, or 99.8%), and the ratio of the initiator is from 0.1% to 10.0% (e.g., 0.1%, 0.5%, 1.0%, 3.0%, 5.0%, 8.0%, or 10.0%), based on 100% of the total weight of the emulsifier, dispersant, first polymeric monomer, and initiator.

Preferably, the total weight percentage of the emulsifier, dispersant, first polymeric monomer and initiator in the first binder emulsion is 2% -30%, such as 2%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 25%, 28% or 30%.

Preferably, cellulose is also added to the system of the first polymerization reaction.

Preferably, the cellulose is used in an amount of 0.1% to 5.0%, for example 0.1%, 0.3%, 0.5%, 0.8%, 1.0%, 2.0%, 3.0%, 4.0% or 5.0% of the total weight of the first polymeric monomer.

Preferably, the emulsifier is one or a combination of at least two of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate or sodium dodecyl sulfonate;

preferably, the dispersing agent is one or a combination of at least two of polyvinyl alcohol, polyvinylpyrrolidone, tetradecane, hexadecane or octadecane;

preferably, the initiator is independently an organic peroxide initiator, an organic azo-based initiator, an inorganic peroxide initiator or a redox initiator.

Preferably, the organic peroxide initiator is benzoyl peroxide or dicumyl peroxide.

Preferably, the organic azo initiator is azobisisobutyronitrile or azobisisoheptonitrile.

Preferably, the inorganic peroxide initiator is ammonium persulfate, sodium persulfate, or potassium persulfate.

Preferably, the redox initiator is ammonium persulfate and sodium sulfite, or ammonium persulfate and sodium bisulfite.

Preferably, the temperature of the first polymerization reaction is 35-98 ℃, for example 35 ℃, 40 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 68 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃, or 98 ℃.

Preferably, the time of the first polymerization reaction is 3 to 15 hours, for example 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 12 hours or 15 hours.

Preferably, the mixed slurry of step (1) has a first binder content of 0.5 to 10.0% (e.g., 0.5%, 1.0%, 2.0%, 3.0%, 5.0%, 7.0%, 9.0%, or 10.0%) and a natural graphite anode material content of 90.0 to 99.5% (e.g., 90.0%, 92.0%, 94.0%, 95.0%, 97.0%, 99.0%, or 99.5%) based on 100% by total weight of the first binder and the natural graphite anode material.

Preferably, the mixed slurry in step (1) further comprises a conductive additive.

Preferably, the conductive additive comprises one or a combination of at least two of conductive graphite, acetylene black, carbon nanotubes or conductive carbon black.

Preferably, the conductive additive is present in the mixed slurry of step (1) in an amount of 0 to 5%, such as 0.5%, 1.0%, 1.5%, 2.0%, 3.0%, 4.0% or 5.0% based on 100% total weight of the first binder and the natural graphite anode material.

Preferably, the wet mixing process of step (1) includes a resonance sound mixing process, a high shear process, grinding, and the like.

Preferably, the wet mixing operation of step (1) comprises using one or a combination of at least two of a ball mill, an electromagnetic ball mill, a disc mill, a pin mill, a high energy impact mill, a fluid energy impact mill, a jet mill, a fluidized bed jet mill, a hammer mill, or an impact mill.

Preferably, the method for removing the solvent in the mixed slurry in the step (1) is any one or a combination of at least two of vacuum drying, centrifugation, freeze drying and spray drying.

Preferably, the total weight of isocyanate-based monomer and hydroxyl terminated acrylate polymer of step (2) is 0.1-10.0%, such as 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0% or 10.0% by weight of the solvent-free mixture.

Preferably, the weight ratio of isocyanate-based monomer to hydroxyl-terminated acrylate polymer of step (2) is from 1:2 to 5:1, for example 1.0:2.0, 1.0:1.0, 1.5:1.0, 1.8:1.0, 2.0:1.0, 2.5:1.0, 3.0:1.0, 3.5:1.0, 4.0:1.0, 4.5:1.0 or 5.0:1.0.

Preferably, the crosslinker of step (2) is used in an amount of 0.1% -10.0%, e.g. 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0% or 10.0% of the total weight of isocyanate-based monomer and hydroxyl-terminated acrylate polymer.

Preferably, the catalyst of step (2) is used in an amount of 0.1% to 5.0%, for example 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0% or 5.0% of the total weight of isocyanate-based monomer and hydroxyl terminated acrylate polymer.

Preferably, the isocyanate-based monomer of step (2) is selected from any one or a combination of at least two of Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), 1, 5-Naphthalene Diisocyanate (NDI), dimethylbiphenyl diisocyanate (TODI), hexamethylene Diisocyanate (HDI), hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, 2, 4-trimethylhexamethylene diisocyanate (TMDI), xylylene Diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), hydrogenated Xylylene Diisocyanate (HXDI), isophorone diisocyanate (IPDI), 4' -dicyclohexylmethane diisocyanate (HMDI), methylcyclohexane diisocyanate (HTDI), 1, 4-cyclohexane diisocyanate, 1, 4-phenylene diisocyanate (PPDI), 1, 3-phenylene diisocyanate or norbornane diisocyanate (NBDI).

Preferably, the hydroxyl terminated acrylate polymer of step (2) is a liquid hydroxyl terminated acrylate polymer, preferably having a number average molecular weight of 100 to 10000.

Preferably, the polymerized monomer of the hydroxyl-terminated acrylate polymer of step (2) comprises any one or a combination of at least two of styrene (St), acrylic Acid (AA), butyl Acrylate (BA), butyl Methacrylate (BMA), hydroxyethyl methacrylate (HEMA), hydroxyethyl acrylate (HEA), hydroxypropyl methacrylate (HPMA) or hydroxypropyl acrylate (HPA).

Preferably, the crosslinking agent in the step (2) is any one or a combination of at least two selected from dihydric alcohol crosslinking agents, trihydric alcohol crosslinking agents, diamine crosslinking agents, alcohol amine crosslinking agents, alicyclic alcohol crosslinking agents, aromatic alcohol crosslinking agents, glycerin allyl ether, glycidyl allyl ether and dicumyl peroxide.

Preferably, the cross-linking agent in step (2) is selected from any one or a combination of at least two of 1, 4-butanediol, ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, glycerol, trimethylolpropane, 3-dichloro-4, 4-diaminodiphenylmethane, 3, 5-dimethylthiotoluenediamine, 3, 5-diethyltoluenediamine, 2, 4-diamino-3, 5-dimethylthiochlorobenzene, isophoronediamine, ethanolamine, diethanolamine, triethanolamine, N-bis (2-hydroxypropyl) aniline, 1, 4-cyclohexanediol, hydrogenated bisphenol A, dimethylenephenyl glycol, hydroquinone bis-beta-hydroxyethyl ether, resorcinol hydroxy ether, glycerol allyl ether, glycidol allyl ether or dicumyl peroxide.

Preferably, the catalyst of step (2) is selected from any one or a combination of at least two of a tertiary amine catalyst or an organometallic compound.

Preferably, the catalyst of step (2) is selected from any one or a combination of at least two of N, N-dimethylcyclohexylamine, dibutyltin dilaurate, bismuth 2-ethylhexanoate or bismuth neodecanoate.

Preferably, the temperature of the in situ polymerization reaction of step (2) is 25-100 ℃, e.g. 25 ℃, 30 ℃, 33 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃ or 100 ℃.

Preferably, the in situ polymerization reaction of step (2) is for a period of time of from 5 to 50 hours, for example 5 hours, 10 hours, 15 hours, 20 hours, 24 hours, 28 hours, 30 hours, 36 hours, 39 hours, 40 hours, 42 hours, 45 hours, 48 hours or 50 hours.

In another aspect, the present invention provides a negative electrode sheet comprising a natural graphite negative electrode material having a surface-attached binder as described above.

In another aspect, the present invention provides an electrochemical energy storage device comprising a natural graphite anode material having a surface bonded with a binder as described above.

Preferably, the electrochemical energy storage device is selected from one of a lithium ion battery, a sodium ion battery, a supercapacitor, a fuel cell or a solar cell.

Compared with the prior art, the invention has the following beneficial effects:

According to the invention, the first binder and the second binder are connected to the surface of the natural graphite anode material, so that the problem of expansion and ageing of the natural graphite anode material in the circulating process can be solved, and meanwhile, the cohesiveness between the natural graphite anode materials and the current collector can be improved, so that the comprehensive performance of the materials is improved, and the lithium ion battery comprising the material has high first coulombic efficiency and circulating stability.

Detailed Description

The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.

Example 1

In this embodiment, a natural graphite anode material with a binder connected to a surface is provided, and the preparation method thereof includes the following steps:

(1) 800.0g of aqueous solution dispersed with 5.0g of polyvinyl alcohol PVA is placed in a 2000L reaction kettle, nitrogen with the purity of more than or equal to 99.9% is introduced under the stirring state of the rotating speed of 250rpm, first polymerization monomer which comprises 90.0g of methyl acrylate, 20.0g of acrylamide monomer and 10.0g of acrylonitrile is added, 0.5g of initiator azodiisobutyronitrile AIBN is added, stirring is continued, nitrogen is continuously introduced, the temperature of the solution is raised to 75 ℃, first polymerization is carried out for 10 hours, a polymerization product is obtained, the polymerization product is decompressed to the vacuum degree of less than 0.1MPa by a vacuum pump, and residual unreacted monomer components are removed, so that the first adhesive is obtained.

(2) 97 parts by weight of a natural graphite anode material (Zhejiang carbon one, CONE-P) and 3 parts by weight of a first binder are taken, metered deionized water is added to prepare a dispersion slurry with the solid content of 40%, and the dispersion slurry is mixed, and is uniformly dispersed by adopting a dispersing machine for 800-30S and 2000-10 min. And (3) drying the dispersed slurry in vacuum at room temperature to remove solvent moisture, so as to obtain a solvent-free mixture.

(3) 5.00g of hexamethylene diisocyanate after water removal and 4.00g of a hydroxyl-terminated acrylate polymer (Soken Kagaku Co., ltd., UT-1001) were added together to a mixing tank, and 0.30g of 1, 4-butanediol as a crosslinking agent, 0.01g of dibutyltin dilaurate as a catalyst were added, and mixed in a defoaming machine at 2000rpm for 10 minutes to obtain a mixture. Taking 1 part by weight of the mixture and 99 parts by weight of the solvent-free mixture obtained in the step (2), and mixing the mixture for 10min at 2000rpm in a defoaming machine. And then standing for 12 hours at normal temperature to perform in-situ polymerization reaction until the binder is solidified, and grinding the obtained product into fine powder by a mortar to obtain the natural graphite anode material with the surface connected with the binder.

Example 2

(1) 800.0g of aqueous solution dispersed with 5.0g of polyvinyl alcohol PVA is placed in a 2000L reaction kettle, nitrogen with the purity of more than or equal to 99.9% is introduced under the stirring state of the rotating speed of 250rpm, first polymerization monomer which comprises 50.0g of methyl acrylate, 10.0g of acrylamide monomer, 20.0g of acrylonitrile and 10.0g of styrene is added, 0.5g of initiator azodiisobutyronitrile AIBN is added, continuous stirring is carried out, nitrogen is continuously introduced, the temperature of the solution is raised to 90 ℃, first polymerization is carried out for 8 hours, a polymerization product is obtained, the pressure of the polymerization product is reduced to the vacuum degree of lower than 0.1MPa by a vacuum pump, and residual unreacted monomer components are removed, so that the first adhesive is obtained.

(2) 92 parts by weight of a natural graphite anode material (Zhejiang carbon one, CONE-P) and 8 parts by weight of a first binder are taken, metered deionized water is added to prepare a dispersion slurry with the solid content of 40%, mixing is carried out, and a dispersing machine is adopted for 800-rotation mixing for 30s, and 2000-rotation mixing is carried out for 10min, so that the slurry is uniformly dispersed. And (3) drying the dispersed slurry in vacuum at room temperature to remove solvent moisture, so as to obtain a solvent-free mixture.

(3) 5.00g of toluene diisocyanate after water removal and 4.00g of a hydroxyl terminated acrylate polymer (Soken Kagaku Co., ltd., UT-1001) were added together to a mixing tank, and 0.30g of propylene glycol as a crosslinking agent and 0.02g of dibutyltin dilaurate as a catalyst were added, and mixed in a defoaming machine at 2000rpm for 10 minutes to obtain a mixture. Taking 1 part by weight of the mixture and 99 parts by weight of the solvent-free mixture obtained in the step (2), and mixing the mixture for 10min at 2000rpm in a defoaming machine. And then standing for 15 hours at normal temperature to react until the binder is solidified, and grinding the obtained product into fine powder by a mortar to obtain the natural graphite anode material with the surface connected with the binder.

Example 3

(1) 800.0g of aqueous solution dispersed with 8.0g of polyvinyl alcohol PVA is placed in a 2000L reaction kettle, nitrogen with the purity of more than or equal to 99.9% is introduced under the stirring state of the rotating speed of 250rpm, first polymerization monomers including 50.0g of methyl acrylate, 15.0g of acrylamide monomers, 15.0g of acrylonitrile and 5.0g of styrene are added, 0.5g of initiator azodiisobutyronitrile AIBN is added, continuous stirring is carried out, nitrogen is continuously introduced, the temperature of the solution is raised to 80 ℃, first polymerization is carried out for 10 hours, a polymerization product is obtained, the pressure of the polymerization product is reduced to the vacuum degree of lower than 0.1MPa by a vacuum pump, and residual unreacted monomer components are removed, so that the first adhesive is obtained.

(2) 99 parts by weight of a natural graphite anode material (Zhejiang carbon one, CONE-P), 0.5 part by weight of a first binder and 0.5 part by weight of conductive carbon black are taken, metered deionized water is added to prepare a dispersion slurry with the solid content of 40%, mixing is carried out, and a dispersing machine is adopted for 800-rotation mixing for 30s, and 2000-rotation mixing is carried out for 10min, so that the slurry is uniformly dispersed. And (3) drying the dispersed slurry in vacuum at room temperature to remove solvent moisture, so as to obtain a solvent-free mixture.

(3) 5.00g of tetramethylxylylene diisocyanate after water removal and 4.50g of a hydroxyl-terminated acrylate polymer (Soken Kagaku Co., ltd., UT-1001) were added together to a mixing tank, and 0.60g of 3, 5-diethyltoluenediamine as a crosslinking agent and 0.02g of bismuth 2-ethylhexanoate as a catalyst were added, and mixed in a defoaming machine at 2000rpm for 10 minutes to obtain a mixture. Taking 5 parts by weight of the mixture and 95 parts by weight of the solvent-free mixture obtained in the step (2), and mixing the mixture for 10min at 2000rpm in a defoaming machine. And then standing for 24 hours at normal temperature to react until the binder is solidified, and grinding the obtained product into fine powder by a mortar to obtain the natural graphite anode material with the surface connected with the binder.

Example 4

(1) Placing 800.0g of an aqueous solution with 2.0g of PVA and 3.0g of sodium dodecyl benzene sulfonate dispersed in a 2000L reaction kettle, introducing nitrogen with the purity of more than or equal to 99.9% under the stirring state of the rotating speed of 250rpm, adding a first polymerization monomer comprising 100.0g of methyl acrylate, 10.0g of acrylamide monomer, 10.0g of acrylonitrile and 10.0g of styrene, adding 0.5g of azo-diisobutyronitrile AIBN serving as an initiator, continuously stirring, continuously introducing nitrogen, heating the solution to 95 ℃, performing a first polymerization reaction for 3 hours to obtain a polymerization product, decompressing the polymerization product to the vacuum degree of less than 0.1MPa by a vacuum pump, and removing residual unreacted monomer components to obtain the first adhesive.

(2) 92 parts by weight of a natural graphite anode material (Zhejiang carbon one, CONE-P), 6 parts by weight of a first binder and 2 parts by weight of conductive carbon black are taken, metered deionized water is added to prepare a dispersion slurry with the solid content of 40%, mixing is carried out, and a dispersing machine is adopted for 800-rotation mixing for 30s, and 2000-rotation mixing is carried out for 10min, so that the slurry is uniformly dispersed. And (3) drying the dispersed slurry in vacuum at room temperature to remove solvent moisture, so as to obtain a solvent-free mixture.

(3) 5.50g of 4,4' -dicyclohexylmethane diisocyanate after water removal and 4.50g of a hydroxyl terminated acrylate polymer (Tiantai chemical, TT 310) were added together to a mixing tank, and 0.20g of 1, 4-cyclohexanediol as a crosslinking agent and 0.01g of bismuth 2-ethylhexanoate as a catalyst were added, and mixed in a defoaming machine at 2000rpm for 10 minutes to obtain a mixture. 0.5 part by weight of the mixture and 99.5 parts by weight of the solvent-free mixture obtained in the step (2) were mixed in a defoaming machine at 2000rpm for 10 minutes. And then standing at normal temperature for 5 hours to react until the binder is solidified, and grinding the obtained product into fine powder by a mortar to obtain the natural graphite anode material with the surface connected with the binder.

Example 5

(1) 800.0g of aqueous solution dispersed with 2.0g of polyvinyl alcohol PVA is placed in a 2000L reaction kettle, nitrogen with the purity of more than or equal to 99.9% is introduced under the stirring state of the rotating speed of 250rpm, first polymerization monomer which comprises 100.0g of methyl acrylate, 10.0g of acrylamide monomer, 10.0g of acrylonitrile and 10.0g of styrene is added, 0.5g of initiator azodiisobutyronitrile AIBN is added, continuous stirring is carried out, nitrogen is continuously introduced, the temperature of the solution is raised to 50 ℃, first polymerization is carried out for 15 hours, a polymerization product is obtained, the pressure of the polymerization product is reduced to the vacuum degree of lower than 0.1MPa by a vacuum pump, and residual unreacted monomer components are removed, so that the first adhesive is obtained.

(2) 98 parts by weight of a natural graphite anode material (Zhejiang carbon one, CONE-P), 1.5 parts by weight of a first binder and 0.5 parts by weight of conductive carbon black are taken, metered deionized water is added to prepare a dispersion slurry with the solid content of 45%, mixing is carried out, and a dispersing machine is adopted for 800-rotation mixing for 30s, and 2000-rotation mixing is carried out for 10min, so that the slurry is uniformly dispersed. And (3) drying the dispersed slurry in vacuum at room temperature to remove solvent moisture, so as to obtain a solvent-free mixture.

(3) 4.50g of isophorone diisocyanate after water removal and 5.00g of hydroxyl-terminated acrylate polymer (Soken Kagaku Co., ltd., UT-1001) were added together to a mixing tank, and 0.80g of N, N-bis (2-hydroxypropyl) aniline as a crosslinking agent, 0.02g of bismuth 2-ethylhexanoate as a catalyst were added, and mixed for 10 minutes in a state of 2000rpm in a defoaming machine, to obtain a mixture. 10 parts by weight of the mixture and 90 parts by weight of the solvent-free mixture obtained in the step (2) were mixed in a defoaming machine at 2000rpm for 10 minutes. And then standing at 40 ℃ for 30 hours to react until the binder is solidified, and grinding the obtained product into fine powder by a mortar to obtain the natural graphite anode material with the surface connected with the binder.

Example 6

(1) 800.0g of aqueous solution dispersed with 5.0g of polyvinyl alcohol PVA is placed in a 2000L reaction kettle, nitrogen with the purity of more than or equal to 99.9% is introduced under the stirring state of the rotating speed of 250rpm, first polymerization monomers including 80.0g of methyl acrylate, 10.0g of acrylamide monomers, 5.0g of acrylonitrile and 10.0g of styrene are added, 0.5g of initiator azodiisobutyronitrile AIBN is added, continuous stirring is carried out, nitrogen is continuously introduced, the temperature of the solution is raised to 75 ℃, first polymerization is carried out for 8 hours, a polymerization product is obtained, the pressure of the polymerization product is reduced to the vacuum degree of less than 0.1MPa by a vacuum pump, and residual unreacted monomer components are removed, so that the first adhesive is obtained.

(2) 93 parts by weight of a natural graphite anode material (Zhejiang carbon one, CONE-P), 3 parts by weight of a first binder and 4 parts by weight of conductive carbon black are taken, metered deionized water is added to prepare a dispersion slurry with the solid content of 40%, mixing is carried out, and a dispersing machine is adopted for 800-rotation mixing for 30s, and 2000-rotation mixing is carried out for 10min, so that the slurry is uniformly dispersed. And (3) drying the dispersed slurry in vacuum at room temperature to remove solvent moisture, so as to obtain a solvent-free mixture.

(3) 5.50g of 1, 5-naphthalene diisocyanate after water removal and 3.50g of a hydroxyl terminated acrylate polymer (Soken Kagaku Co., ltd., UT-1001) were added together to a mixing pot, and 0.40g of triethanolamine as a crosslinking agent, 0.01g of bismuth 2-ethylhexanoate as a catalyst were added, and mixed for 10 minutes in a state of 2000rpm in a defoaming machine to obtain a mixture. 8 parts by weight of the mixture and 92 parts by weight of the solvent-free mixture obtained in the step (2) were mixed in a defoaming machine at 2000rpm for 10 minutes. And then standing at 100 ℃ for 5 hours to react until the binder is solidified, and grinding the obtained product into fine powder by a mortar to obtain the natural graphite anode material with the surface connected with the binder.

Example 7

The only difference from example 1 is that step (1) is as follows:

(1) 800.0g of aqueous solution dispersed with 5.0g of polyvinyl alcohol PVA is placed in a 2000L reaction kettle, nitrogen with the purity of more than or equal to 99.9% is introduced under the stirring state of the rotating speed of 250rpm, first polymerization monomer which comprises 90.0g of methyl acrylate, 20.0g of acrylamide monomer, 10.0g of acrylonitrile, 0.5g of hydroxypropyl cellulose is added, 0.5g of initiator azodiisobutyronitrile AIBN is added, stirring is continued, nitrogen is continuously introduced, the temperature of the solution is raised to 75 ℃, first polymerization is carried out for 10 hours, a polymerization product is obtained, the vacuum pump is used for reducing the pressure of the polymerization product to the vacuum degree of less than 0.1MPa, and residual unreacted monomer components are removed, so that the first adhesive is obtained. The other steps were the same as in example 1.

Example 8

The only difference from example 7 is that the amount of hydroxypropyl cellulose used was 6g.

Example 9

The difference from example 1 is only that the first polymerization monomer in step (1) comprises only 99g of methyl acrylate and 21g of acrylamide monomer.

Example 10

The difference from example 1 is only that the first polymerization monomer in step (1) comprises only 108g of methyl acrylate and 12g of acrylonitrile.

Example 11

The difference from example 2 was only that the first polymerization monomer in step (1) included only 75g of methyl acrylate and 15g of styrene.

Example 12

The difference from example 1 is only that the first polymerization monomer in step (1) comprises only 120g of methyl acrylate.

Example 13

The only difference from example 1 is that the first polymerization monomer in step (1) includes only 120g of acrylamide monomer.

Example 14

The difference from example 2 is only that the first polymerization monomer in step (1) comprises only 90g of styrene.

Example 15

The difference from example 1 is only that the first polymerization monomer in step (1) comprises only 120g of acrylonitrile.

Comparative example 1

The only difference from example 1 is that the hydroxyl terminated acrylate polymer in step (3) is replaced with a polyester polyol (pascal, polyester polyol).

Comparative example 2

The only difference from example 1 is that the hydroxyl-terminated acrylate polymer in step (3) was replaced with a hydroxyl-terminated ethylene oxide polymer (Tiantai chemistry, TT 310).

Comparative example 3

The difference from example 1 is only that the in-situ polymerization of step (3) is not performed, but the solvent-free mixture obtained in step (2) is directly used as a natural graphite negative electrode material of a surface-bonding binder.

Comparative example 4

The comparative example provides a modified natural graphite anode material, which is prepared by the following steps:

5.00g of hexamethylene diisocyanate after water removal and 4.00g of a hydroxyl-terminated acrylate polymer (Soken Kagaku Co., ltd., UT-1001) were added together to a mixing tank, and 0.30g of 1, 4-butanediol as a crosslinking agent, 0.01g of dibutyltin dilaurate as a catalyst were added, and mixed in a defoaming machine at 2000rpm for 10 minutes to obtain a mixture. 1 part by weight of the mixture and 99 parts by weight of natural graphite negative electrode material are taken and mixed for 10min in a defoaming machine at 2000 rpm. And then standing for 12 hours at normal temperature to perform in-situ polymerization reaction until the binder is solidified, and grinding the obtained product into fine powder by a mortar to obtain the natural graphite anode material with the surface connected with the binder.

Application examples 1 to 15 and comparative application examples 1 to 4

The prepared natural graphite anode material is prepared into an anode sheet, and specifically comprises the following components: mixing the natural graphite anode materials obtained in examples 1-15 and comparative examples 1-4 with a conductive agent carbon black (Surper P) PAA binder according to a mass ratio of 96.5:1.5:2.0 to obtain slurry, and then coating the slurry on a copper foil to form an anode sheet.

Assembling the prepared negative electrode plate and lithium metal plate into a lithium ion button cell, and assembling the LiPF ₆ After the completion of the snap-on assembly, the first coulombic efficiency and cycle of the capacity were tested as follows, dissolved in an electrolyte of ethylene carbonate/diethyl carbonate/methylethyl carbonate=2:3:1 at a concentration of 1 mol/l: standing for 2h; constant current discharge: 0.10C to 0.005V;0.08C to 0.001V;0.05C to 0.001V;0.02C to 0.001V; standing for 10min; constant current charging: 0.10C to 1.500V.

The capacity first coulombic efficiency and the cycling test results are shown in table 1.

TABLE 1

/>

As can be seen from the results of table 1, the natural graphite anode material with the surface connected with the binder of the present invention can achieve a first coulomb efficiency of 94% or more, a capacity retention rate of 86% or more after 1000 cycles of cycle, and good battery efficiency and cycle stability.

In comparative example 1, since the hydroxyl-terminated acrylate polymer in the second binder is replaced with a polyester polyol, the polyester polyol has a weaker surface force than the natural graphite, resulting in a decrease in initial coulombic efficiency of the battery and a decrease in cycling stability.

In comparative example 2, since the hydroxyl-terminated acrylate polymer in the second binder was replaced with the hydroxyl-terminated ethylene oxide polymer, the hydroxyl-terminated ethylene oxide polymer was weaker in surface force than the hydroxyl-terminated acrylate polymer, compared with the natural graphite, resulting in a decrease in initial coulombic efficiency of the battery and a decrease in cycling stability.

In-situ polymerization in step (3) was not performed in comparative example 3, so that the binder included in the obtained binder-surface-bonded natural graphite anode material included only the first binder, and the binder included in the binder-surface-bonded natural graphite anode material included only the second binder, which were obtained in comparative example 4, failed to form a good polymer-coated network structure, so that the battery of comparative examples 3 and 4 was reduced in coulombic efficiency for the first time, while the cycle stability was reduced.

The applicant states that the present invention is described by way of the above examples as a natural graphite anode material with a surface-bonded binder, and a method for preparing the same and applications thereof, but the present invention is not limited to the above examples, i.e., it is not meant that the present invention must be practiced in dependence upon the above examples. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of raw materials for the product of the present invention, addition of auxiliary components, selection of specific modes, etc., falls within the scope of the present invention and the scope of disclosure.

Claims

1. The natural graphite anode material with the surface connected with the binder is characterized by comprising a natural graphite anode material and the binder with the surface connected with the natural graphite anode material, wherein the binder comprises a first binder and a second binder, the first binder comprises a first polymer, a polymerization monomer of the first polymer is any one or a combination of at least two of an acrylic monomer, an acrylamide monomer, an acrylonitrile monomer or a styrene monomer, and the second binder is bi-component polyacrylate;

the preparation raw materials of the bi-component polyacrylate comprise isocyanate monomers, hydroxyl-terminated acrylate polymers, a cross-linking agent and a catalyst;

the hydroxyl-terminated acrylate polymer is a liquid hydroxyl-terminated acrylate polymer;

the second binder is obtained by in-situ polymerization on the surface of the natural graphite anode material connected with the first binder;

the first binder is of a particle structure, the second binder is of a non-particle structure, and the first binder and the second binder form a polymer network on the surface of the natural graphite anode material.

2. The natural graphite negative electrode material with a surface-attached binder according to claim 1, wherein the acrylic monomer is selected from any one or a combination of at least two of methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, isooctyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, isooctyl methacrylate, hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, sodium acrylate, lithium acrylate, acrylic acid, lithium methacrylate, lithium itaconate, lithium monobutyl itaconate, or monobutyl itaconate.

3. The natural graphite anode material with a surface-attached binder according to claim 1, wherein the acrylamide-based monomer is selected from any one or a combination of at least two of acrylamide, methacrylamide, N-methylolacrylamide or N, N-dimethylacrylamide.

4. The binder-surfaced natural graphite anode material of claim 1, wherein the first binder further comprises cellulose, the cellulose being mixed with the first polymer.

5. The natural graphite anode material with a surface-attached binder according to claim 4, wherein the cellulose is selected from any one or a combination of at least two of cellulose acetate, methylcellulose, ethylcellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, nitrocellulose, carboxymethyl cellulose, carboxyethyl cellulose, carboxypropyl cellulose, carboxyisopropyl cellulose, sodium nitrocellulose, and sodium carboxyalkyl cellulose.

6. The natural graphite anode material to which a binder is attached to the surface according to claim 1, wherein the isocyanate-based monomer is selected from any one or a combination of at least two of toluene diisocyanate, diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, dimethylbiphenyl diisocyanate, hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, 2, 4-trimethylhexamethylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, 4' -dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, 1, 4-cyclohexane diisocyanate, 1, 4-benzene diisocyanate, 1, 3-benzene diisocyanate, and norbornane diisocyanate.

7. The binder-attached natural graphite anode material according to claim 1, wherein the hydroxyl-terminated acrylate polymer has a number average molecular weight of 100 to 10000.

8. The binder-attached natural graphite anode material of claim 1, wherein the polymerized monomer of the hydroxyl-terminated acrylate polymer is one or a combination of at least two of styrene, acrylic acid, butyl acrylate, butyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, or hydroxypropyl acrylate.

9. The natural graphite anode material with a surface-attached binder according to claim 1, wherein the crosslinking agent is selected from any one or a combination of at least two of 1, 4-butanediol, ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, glycerol, trimethylolpropane, 3-dichloro-4, 4-diaminodiphenylmethane, 3, 5-dimethylthiotoluenediamine, 3, 5-diethyltoluenediamine, 2, 4-diamino-3, 5-dimethylthiochlorobenzene, isophoronediamine, ethanolamine, diethanolamine, triethanolamine, N-bis (2-hydroxypropyl) aniline, 1, 4-cyclohexanediol, hydrogenated bisphenol a, dimethylenephenyl glycol, hydroquinone bis- β -hydroxyethyl ether, resorcinol hydroxy ether, glycerol allyl ether, glycidyl allyl ether, or dicumyl peroxide.

10. The binder-attached natural graphite anode material according to claim 1, wherein the catalyst is selected from any one or a combination of at least two of a tertiary amine catalyst or an organometallic compound.

11. The natural graphite negative electrode material with a surface-attached binder according to claim 10, wherein the catalyst is selected from any one or a combination of at least two of N, N-dimethylcyclohexylamine, dibutyltin dilaurate, bismuth 2-ethylhexanoate, or bismuth neodecanoate.

12. The binder-surfaced natural graphite anode material of claim 1, wherein the first polymer has a glass transition temperature Tg in the range of-50 to 200 ℃.

13. The natural graphite anode material with a surface-attached binder according to claim 1, wherein the particle size of the first binder is 200-nm-10 μm.

14. The natural graphite anode material with a surface-attached binder according to claim 1, wherein the first binder is polymerized by emulsion polymerization, microemulsion polymerization, suspension polymerization or microsuspension polymerization.

15. The method for preparing a natural graphite anode material with a surface-bonded binder according to any one of claims 1 to 14, comprising the steps of:

(2) Mixing an isocyanate monomer, a hydroxyl-terminated acrylate polymer, a cross-linking agent and a catalyst, and then mixing with the solvent-free mixture obtained in the step (1) to perform in-situ polymerization reaction to obtain the natural graphite anode material with the surface connected with the binder.

16. The method of preparing the first binder of step (1) comprising the steps of:

adding a first polymerization monomer and an initiator into an aqueous solution containing an emulsifier and/or a dispersing agent, and performing a first polymerization reaction to obtain a first binder emulsion, wherein the obtained binder emulsion removes solvent water to obtain a first binder, and the first polymerization monomer is any one or a combination of at least two of an acrylic monomer, an acrylamide monomer, an acrylonitrile monomer and a styrene monomer.

17. The method of claim 16, wherein the total weight of the emulsifier, dispersant, first polymeric monomer and initiator is 0.1% to 10.0%, the weight of the first polymeric monomer is 80.0% to 99.8%, and the weight of the initiator is 0.1% to 10.0%, based on 100% of the total weight of the emulsifier, dispersant, first polymeric monomer and initiator.

18. The method of claim 16, wherein the total weight percent of the emulsifier, dispersant, first polymeric monomer, and initiator in the first binder emulsion is 2% to 30%.

19. The method according to claim 16, wherein the acrylic monomer is selected from any one or a combination of at least two of methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, isooctyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, isooctyl methacrylate, hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, sodium acrylate, lithium acrylate, acrylic acid, lithium methacrylate, methacrylic acid, lithium itaconic acid, lithium monobutyl itaconate, or monobutyl itaconate.

20. The method of claim 16, wherein the acrylamide monomer is selected from any one or a combination of at least two of acrylamide, methacrylamide, N-methylolacrylamide, or N, N-dimethylacrylamide.

21. The method of claim 16, wherein cellulose is further added to the first polymerization system.

22. The method according to claim 21, wherein the cellulose is selected from any one or a combination of at least two of cellulose acetate, methylcellulose, ethylcellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, nitrocellulose, carboxymethyl cellulose, carboxyethyl cellulose, carboxypropyl cellulose, carboxyisopropyl cellulose, sodium nitrocellulose, and sodium carboxyalkyl cellulose.

23. The method of claim 21, wherein the cellulose is present in an amount of from 0.1% to 5.0% by weight based on the total weight of the first polymeric monomer.

24. The method of claim 16, wherein the emulsifier is one or a combination of at least two of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, or sodium dodecyl sulfonate.

25. The method of claim 16, wherein the dispersant is one or a combination of at least two of polyvinyl alcohol, polyvinylpyrrolidone, tetradecane, hexadecane, or octadecane.

26. The method of preparation according to claim 16, wherein the initiator is independently an organic peroxide initiator, an organic azo-based initiator, an inorganic peroxide initiator or a redox initiator.

27. The method of claim 26, wherein the organic peroxide initiator is benzoyl peroxide or dicumyl peroxide.

28. The method according to claim 26, wherein the organic azo-based initiator is azobisisobutyronitrile or azobisisoheptonitrile.

29. The method of claim 26, wherein the inorganic peroxide initiator is ammonium persulfate, sodium persulfate, or potassium persulfate.

30. The method of claim 26, wherein the redox initiator is ammonium persulfate and sodium sulfite, or ammonium persulfate and sodium bisulfite.

31. The method of claim 16, wherein the temperature of the first polymerization reaction is 35-98 ℃.

32. The method of claim 16, wherein the first polymerization reaction is carried out for a period of time ranging from 3 to 15 h.

33. The method according to claim 15, wherein the mixed slurry in step (1) has a first binder content of 0.5 to 10.0% and a natural graphite anode material content of 90.0 to 99.5% based on 100% by weight of the total of the first binder and the natural graphite anode material.

34. The method of claim 15, wherein the mixed slurry of step (1) further comprises a conductive additive.

35. The method of claim 34, wherein the conductive additive comprises one or a combination of at least two of conductive graphite, acetylene black, carbon nanotubes, or conductive carbon black.

36. The method of claim 34, wherein the conductive additive is present in the mixed slurry of step (1) in an amount of 0 to 5% based on 100% total weight of the first binder and the natural graphite negative electrode material.

37. The method of claim 15, wherein the wet mixing process of step (1) comprises a resonance sound mixing process, a high shear process, and a milling process.

38. The method of claim 15, wherein the wet mixing operation of step (1) comprises using one or a combination of at least two of a ball mill, an electromagnetic ball mill, a disc mill, a pin mill, a high energy impact mill, a fluid energy impact mill, a jet mill, a fluidized bed jet mill, a hammer mill, or an impact mill.

39. The method of claim 15, wherein the method of removing the solvent from the mixed slurry in step (1) is any one or a combination of at least two of vacuum drying, centrifugation, freeze-drying, and spray-drying.

40. The method of claim 15, wherein the total weight of isocyanate-based monomer and hydroxyl terminated acrylate polymer in step (2) is 0.1 to 10.0% by weight of the solvent-free mixture.

41. The method of claim 15, wherein the weight ratio of isocyanate-based monomer to hydroxyl-terminated acrylate polymer in step (2) is 1:2 to 5:1.

42. The method of claim 15, wherein the cross-linking agent in step (2) is used in an amount of 0.1% to 10.0% based on the total weight of isocyanate-based monomer and hydroxyl-terminated acrylate polymer.

43. The method of claim 15, wherein the catalyst of step (2) is used in an amount of 0.1% to 5.0% based on the total weight of isocyanate-based monomer and hydroxyl-terminated acrylate polymer.

44. The method according to claim 15, wherein the isocyanate-based monomer in the step (2) is selected from any one or a combination of at least two of toluene diisocyanate, diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, dimethylbiphenyl diisocyanate, hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, 2, 4-trimethylhexamethylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, 4' -dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, 1, 4-cyclohexane diisocyanate, 1, 4-benzene diisocyanate, 1, 3-benzene diisocyanate, and norbornane diisocyanate.

45. The method of claim 15, wherein the hydroxy-terminated acrylate polymer in step (2) is a liquid hydroxy-terminated acrylate polymer having a number average molecular weight of 100 to 10000.

46. The method of claim 15, wherein the polymerized monomer of the hydroxyl-terminated acrylate polymer of step (2) is one or a combination of at least two of styrene, acrylic acid, butyl acrylate, butyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, or hydroxypropyl acrylate.

47. The method according to claim 15, wherein the crosslinking agent in the step (2) is selected from any one or a combination of at least two of a glycol crosslinking agent, a triol crosslinking agent, a diamine crosslinking agent, an alcohol amine crosslinking agent, an alicyclic alcohol crosslinking agent, an aromatic alcohol crosslinking agent, glycerin allyl ether, glycidyl allyl ether, and dicumyl peroxide.

48. The method according to claim 15, wherein the crosslinking agent in the step (2) is selected from any one or a combination of at least two of 1, 4-butanediol, ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, glycerol, trimethylolpropane, 3-dichloro-4, 4-diaminodiphenylmethane, 3, 5-dimethylthiotoluenediamine, 3, 5-diethyltoluenediamine, 2, 4-diamino-3, 5-dimethylthiochlorobenzene, isophoronediamine, ethanolamine, diethanolamine, triethanolamine, N-bis (2-hydroxypropyl) aniline, 1, 4-cyclohexanediol, hydrogenated bisphenol a, dimethylenephenyl glycol, hydroquinone bis- β -hydroxyethyl ether, resorcinol hydroxy ether, glycerol allyl ether, glycidol allyl ether, and dicumyl peroxide.

49. The method of claim 15, wherein the catalyst of step (2) is selected from any one or a combination of at least two of a tertiary amine catalyst or an organometallic compound.

50. The process according to claim 15, wherein the catalyst of step (2) is selected from any one or a combination of at least two of N, N-dimethylcyclohexylamine, dibutyltin dilaurate, bismuth 2-ethylhexanoate or bismuth neodecanoate.

51. The method of claim 15, wherein the in situ polymerization reaction in step (2) is carried out at a temperature of 25-100 ℃.

52. The method of claim 15, wherein the in situ polymerization in step (2) is carried out for a period of time ranging from 5 to 50 h.

53. A negative electrode sheet, characterized in that the negative electrode sheet comprises the natural graphite negative electrode material of any one of claims 1 to 14, the surface of which is connected with a binder.

54. An electrochemical energy storage device comprising a natural graphite anode material having a surface bonded with a binder as defined in any one of claims 1-14.

55. An electrochemical energy storage device as in claim 54, wherein said electrochemical energy storage device is selected from one of a lithium ion battery, a sodium ion battery, a super capacitor, a fuel cell, or a solar cell.