A negative electrode material, a preparation method therefor, and an application thereof

Abstract

In order to improve the electrochemical performance of the negative electrode material and relieve the volume expansion of the silicon base, the application provides a negative electrode material and a preparation method and application thereof.The negative electrode material comprises silicon-carbon particles and an organic coating layer, the organic coating layer is on the surface of the silicon-carbon particles, the organic coating layer has a porous structure; in the direction away from the surface of the silicon-carbon particles, the density of functional groups in the organic coating layer is overall increased in gradient, and the pore size of the porous structure is overall decreased in gradient.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a negative electrode material and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of electronic devices and electric vehicles, higher requirements are put forward for the energy density and cycle performance of lithium ion batteries. Silicon-carbon composite material has become a highly potential negative electrode material due to its high theoretical specific capacity. Silicon-carbon material prepared by chemical vapor deposition (CVD silicon-carbon) combines the high capacity of silicon and the conductivity and stability of carbon. However, in the charging and discharging process, the volume expansion of silicon is as high as 300%, which leads to the pulverization of the material structure, the instability of the electrode and electrolyte interface, the rapid decay of the battery capacity, the shortening of the cycle life, and greatly limits its practical application.

[0003] At present, it is a common means to improve the electrochemical performance of silicon-carbon material by coating modification. However, there are some problems in traditional coating materials and methods, such as the single structure of ordinary polymers, the limited optimization of ion and electron transmission, and the difficulty of carbon coating layer to effectively buffer the volume change of silicon, resulting in the reduction of cycle stability.

[0004] Therefore, there is an urgent need for a negative electrode material to solve the technical problems of volume expansion, poor cycle stability and low ion transmission efficiency of silicon-carbon negative electrode material. SUMMARY

[0005] The purpose of the present application is to provide a negative electrode material and a preparation method and application thereof to solve the above technical problems.

[0006] The technical solution adopted by the present application to solve the above technical problems is as follows:

[0007] In a first aspect of the present application, a negative electrode material is provided, comprising silicon-carbon particles and an organic coating layer, the organic coating layer being on the surface of the silicon-carbon particles, the organic coating layer having a porous structure.

[0008] In the direction away from the surface of the silicon-carbon particles, the density of functional groups in the organic coating layer as a whole increases in gradient, the pore size of the porous structure as a whole decreases in gradient, and the organic coating layer comprises at least two coating layers.

[0009] Optionally, the organic coating layer comprises a first coating layer and a second coating layer, the first coating layer comprises a first covalent organic framework, the second coating layer comprises a second covalent organic framework, and the second covalent organic framework is coated on the surface of the first covalent organic framework.

[0010] The pore size of the first covalent organic framework is larger than the second covalent organic framework, and the functional group density in the first covalent organic framework is smaller than the second covalent organic framework.

[0011] Optionally, the pore size of the first covalent organic framework ranges from 5 to 20 nm, and the pore size of the second covalent organic framework ranges from 1 to 5 nm.

[0012] Optionally, the functional group density of the first covalent organic framework is 5 to 10 per nm 2 , and the functional group density of the second covalent organic framework is 15 to 25 per nm 2 .

[0013] Optionally, the particle size of the silicon-carbon particles ranges from 4 to 20 µm.

[0014] Optionally, the mass percentage of silicon in the silicon-carbon particles is 30 to 70%, and the mass percentage of carbon is 30 to 70%.

[0015] Optionally, the thickness of the organic coating layer is 50 to 500 nm.

[0016] In a second aspect of the present application, a preparation method of a negative electrode material is provided, comprising the following steps:

[0017] Dissolving the organic monomer A, the organic monomer B and the catalyst in an organic solvent to prepare a pre-assembly solution;

[0018] Adding silicon-carbon particles to the pre-assembly solution to perform a first polymerization reaction at a first temperature to obtain a first reaction liquid, and a first coating layer is formed on the surface of the silicon-carbon particles in the first reaction liquid;

[0019] Adding the organic monomer C, the organic monomer D and the accelerator to the first reaction liquid to perform a second polymerization reaction at a second temperature, and a second coating layer is formed outside the first coating layer to obtain a second reaction liquid containing a crude product;

[0020] Sequentially performing post-treatment and vacuum drying on the crude product to obtain a negative electrode material;

[0021] The first temperature is less than the second temperature;

[0022] The organic monomer A comprises at least one of a phenyl-containing aldehyde compound and a phenyl-containing acid anhydride compound;

[0023] The organic monomer B comprises an amine compound;

[0024] The organic monomer C comprises at least one of a carboxylic acid compound, an aldehyde compound, a boric acid compound and a phenol compound;

[0025] The organic monomer D comprises at least one of an amine compound and a phenol compound.

[0026] Optionally, the first temperature is 40-60℃, and the reaction time of the first polymerization reaction is 1-3h.

[0027] The second temperature is 60-80℃, and the reaction time of the second polymerization reaction is 2-5h.

[0028] Optionally, the organic monomer A comprises at least one of triformylphenyl, pyromellitic dianhydride, terephthaldehyde, 2,5-dimethoxyterephthaldehyde;

[0029] The organic monomer B comprises at least one of p-phenylenediamine, tartaric acid dihydrazide, 1,3,5-tris(4-aminophenyl)benzene;

[0030] And / or, the organic monomer C comprises at least one of 2,5-dihydroxyterephthalic acid, 2,5-dihydroxyterephthaldehyde, 2-amino terephthalic acid, 2,5-dicyanoterephthaldehyde, tetra(4-formylphenyl)methane, 1,4-benzenediboronic acid, 2,3,6,7,10,11-hexahydroxytriphenylene;

[0031] The organic monomer D comprises at least one of ethylenediamine, hexanediamine, 1,3,5-tris(4-aminophenyl)triazine, 4,4',4''-triaminotriphenylamine, benzidine-3,3',5,5'-tetraamine, hydroquinone, 1,3,5-trihydroxybenzene.

[0032] Optionally, the molar ratio of the organic monomer A to the organic monomer B is 1:1-1:2;

[0033] And / or, the molar ratio of the organic monomer C to the organic monomer D is 1:1-1:1.5.

[0034] Optionally, the catalyst comprises at least one of acetic acid, trifluoroacetic acid, p-toluenesulfonic acid, scandium triflate, tris(pentafluorophenyl)borane;

[0035] The promoter comprises at least one of piperidine, triethylamine, 1,8-diazabicycloundec-7-ene, 1,4-diazabicyclo[2.2.2]octane, zinc acetate, scandium triflate, tetrabutylammonium bromide.

[0036] Optionally, the amount of the catalyst is 5-15% of the total molar amount of the organic monomer A and the organic monomer B;

[0037] And / or, the amount of the promoter is 3-8% of the total molar amount of the organic monomer C and the organic monomer D.

[0038] In a third aspect, the present application provides a negative electrode sheet, comprising a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer being arranged on at least one side of the negative electrode current collector, the negative electrode active material layer comprising the negative electrode material described above or the negative electrode material prepared by the preparation method described above.

[0039] In a fourth aspect, the present application provides a battery comprising the negative electrode sheet described above.

[0040] The organic coating layer of the negative electrode material of the present application has a gradient porous structure, the part close to the silicon-carbon particles has a larger pore size, has good flexibility and deformability, and can provide sufficient space for the volume expansion of silicon, thereby effectively relieving the stress generated by the volume expansion of silicon; in the direction away from the surface of the silicon-carbon particles, the pore size is smaller and the density of functional groups is larger, this structure can limit the excessive expansion of silicon, thereby maintaining the overall structural stability of the negative electrode material, reducing the pulverization and shedding of the negative electrode material, and thereby improving the cycle performance of the battery.

[0041] The gradient porous structure of the organic coating layer is conducive to the rapid diffusion and transmission of lithium ions in the organic coating layer, reduces the ion transmission resistance, and the abundant and density-gradient-increasing functional groups not only can provide more active sites, enhance the interaction between the negative electrode material and lithium ions, improve the internal conduction of electrons in the negative electrode material, and improve the charge and discharge efficiency of the material.

[0042] The organic coating layer has good interfacial bonding force with the silicon-carbon particles, and the gradient structure can make the stress distribution at the interface more uniform, reduce the rupture of the interface and the penetration of electrolyte, thereby forming a stable electrode-electrolyte interface, reducing the irreversible capacity loss in the battery, and improving the cycle life and safety of the battery.

[0043] The preparation method of the negative electrode material of the present application constructs the organic coating layer with a gradient structure by step-by-step assembly, the preparation process is simple, the reaction conditions are mild and easy to control, is suitable for large-scale production, and can accurately regulate the gradient structure of the organic coating layer to meet different application requirements. DETAILED DESCRIPTION

[0044] In order to make the technical problems, technical solutions and beneficial effects solved by the present application more clear and explicit, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0045] The negative electrode material of the present application comprises silicon-carbon particles and an organic coating layer, the organic coating layer being on the surface of the silicon-carbon particles, the organic coating layer having a porous structure;

[0046] The density of the functional groups in the organic coating layer as a whole increases in a gradient manner in a direction away from the surface of the silicon-carbon particles, and the pore size of the porous structure as a whole decreases in a gradient manner, and the organic coating layer comprises at least two coating layers.

[0047] Specifically, the gradient porous structure of the organic coating layer is conducive to the rapid diffusion and transmission of lithium ions in the organic coating layer, reduces the ion transmission resistance, and the abundant and density-gradient-increasing functional groups not only can provide more active sites, enhance the interaction between the negative electrode material and lithium ions, improve the internal conduction of electrons in the negative electrode material, and improve the charge and discharge efficiency of the material; the organic coating layer has good interfacial bonding force with the silicon-carbon particles, and the gradient structure can make the stress distribution at the interface more uniform, reduce the rupture of the interface and the penetration of the electrolyte, thereby forming a stable electrode-electrolyte interface, reducing the irreversible capacity loss in the battery, and improving the cycle life and safety of the battery.

[0048] In some embodiments, the organic coating layer comprises a first coating layer and a second coating layer, the first coating layer comprises a first covalent organic framework, and the second coating layer comprises a second covalent organic framework, and the second covalent organic framework is coated on the surface of the first covalent organic framework.

[0049] The pore size of the first covalent organic framework is larger than that of the second covalent organic framework, and the density of the functional groups in the first covalent organic framework is smaller than that of the second covalent organic framework.

[0050] Specifically, the organic coating layer of the negative electrode material has a gradient porous structure, the part close to the silicon-carbon particles, i.e. the first covalent organic framework, has a larger pore size, good flexibility and deformability, and can provide sufficient space for the volume expansion of silicon, thereby effectively relieving the stress generated by the volume expansion of silicon; in a direction away from the surface of the silicon-carbon particles, the pore size of the second covalent organic framework is smaller and the density of the functional groups is larger, this structure can limit the excessive expansion of silicon, thereby maintaining the overall structural stability of the negative electrode material, reducing the pulverization and shedding of the negative electrode material, thereby improving the cycle performance of the battery, and the larger density of the functional groups can improve the initial specific discharge capacity of the battery.

[0051] In some embodiments, the pore size of the first covalent organic framework ranges from 5 to 20 nm, and the pore size of the second covalent organic framework ranges from 1 to 5 nm.

[0052] Specifically, the pore size of the first covalent organic framework includes but is not limited to 5 nm, 7 nm, 9 nm, 10 nm, 12 nm, 15 nm, 16 nm, 18 nm, 20 nm, the pore size of the first covalent organic framework is larger, and the first covalent organic framework has good flexibility and deformability. The pore size of the second covalent organic framework includes but is not limited to 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, and the pore size of the second covalent organic framework is smaller, and the second covalent organic framework has good supportability.

[0053] In some embodiments, the functional group density of the first covalent organic framework is 5-10 / nm 2 , and the functional group density of the second covalent organic framework is 15-25 / nm 2 .

[0054] Specifically, the functional group density of the first covalent organic framework includes but is not limited to 5 / nm 2 , 6 / nm 2 , 8 / nm 2 , 9 / nm 2 , 10 / nm 2 . The functional group density of the second covalent organic framework includes but is not limited to 15 / nm 2 , 16 / nm 2 , 17 / nm 2 , 18 / nm 2 , 19 / nm 2 , 20 / nm 2 , 21 / nm 2 , 22 / nm 2 , 23 / nm 2 , 24 / nm 2 , 25 / nm 2 . The functional group density of the second covalent organic framework is larger, and this structure can limit the excessive expansion of silicon, thereby maintaining the overall structural stability of the negative electrode material.

[0055] In some embodiments, the particle size of the silicon-carbon particles ranges from 4 to 20 µm.

[0056] Specifically, the particle size of the silicon-carbon particles includes but is not limited to 4 µm, 5 µm, 8 µm, 11 µm, 13 µm, 16 µm, 17 µm, 19 µm, and 20 µm. The particle size of the silicon-carbon particles in this range can better balance the volume expansion and the electrical conductivity.

[0057] In some embodiments, the mass percentage of silicon in the silicon-carbon particles is 30-70%, and the mass percentage of carbon is 30-70%.

[0058] Specifically, the mass percentage of silicon in the silicon-carbon particles includes, but is not limited to, 30%, 36%, 43%, 49%, 54%, 58%, 61%, 67%, and 70%; the mass percentage of carbon includes, but is not limited to, 30%, 36%, 43%, 49%, 54%, 58%, 61%, 67%, and 70%. If the mass percentage of silicon is high, the overall expansion rate of the silicon-carbon particles will greatly increase, which is easy to cause the cracking of the electrode and lead to a sharp decrease in the cycle life. At the same time, it will also cause the decrease in the overall conductivity of the negative electrode material and the increase in the charge transport resistance. On the contrary, if the mass percentage of silicon is low, the cycle life can be prolonged, but the decrease in the silicon content cannot meet the demand of high-energy-density batteries. If the mass percentage of carbon is low, the carbon matrix cannot completely wrap the silicon particles, the volume expansion of silicon cannot be effectively inhibited, the conductivity decreases, and the cycle stability deteriorates. On the contrary, if the mass percentage of carbon is too high, the silicon content will be affected, and the energy density of the battery will be affected.

[0059] In some embodiments, the thickness of the organic coating layer is 50-500 nm.

[0060] Specifically, the thickness of the organic coating layer includes, but is not limited to, 50 nm, 85 nm, 130 nm, 175 nm, 220 nm, 280 nm, 315 nm, 390 nm, 455 nm, and 500 nm. If the thickness of the coating layer is too thin, the space for accommodating the volume expansion of silicon becomes small, and cracks, voids, or discontinuous regions are easy to appear, which leads to structural collapse. If the thickness of the coating layer is too thick, the charge transport resistance will increase, and the electrocatalytic performance will be weakened.

[0061] The application provides a preparation method of a negative electrode material.

[0062] The organic monomer A, the organic monomer B, and the catalyst are dissolved in an organic solvent to prepare a pre-assembly solution;

[0063] The silicon-carbon particles are added to the pre-assembly solution, a first polymerization reaction is carried out at a first temperature, and a first reaction liquid is obtained, wherein a first coating layer is formed on the surface of the silicon-carbon particles in the first reaction liquid;

[0064] The organic monomer C, the organic monomer D, and the accelerator are added to the first reaction liquid, a second polymerization reaction is carried out at a second temperature, a second coating layer is formed outside the first coating layer, and a second reaction liquid containing a crude product is obtained;

[0065] The crude product is sequentially subjected to post-treatment and vacuum drying to obtain the negative electrode material;

[0066] The first temperature is less than the second temperature;

[0067] The organic monomer A includes at least one of an aldehyde compound containing a phenyl group and an acid anhydride compound containing a phenyl group.

[0068] The organic monomer B includes amine compounds;

[0069] The organic monomer C includes at least one of carboxylic acid compounds, aldehyde compounds, boric acid compounds and phenolic compounds;

[0070] The organic monomer D includes at least one of amine compounds and phenolic compounds.

[0071] Specifically, the organic monomer A and the organic monomer B are monomers with large steric hindrance and long chain segments, and the organic monomer C and the organic monomer D are monomers with small steric hindrance and high-density functional groups.

[0072] Specifically, the formation of the gradient structure is mainly related to the structure of the organic monomer, the reaction condition and the assembly mode. The structure of the organic monomer is mainly related to the steric hindrance and the number of functional groups. The steric hindrance is manifested in the length of the chain segment and the side chain and the number of benzene rings. The monomer with large steric hindrance and long chain segment has more benzene rings and longer chain segment and side chain, and the structure is more stretched, which promotes the first coating layer formed in the later stage to have a larger pore size. The monomer with small steric hindrance and high-density functional groups has shorter chain segment (such as short-chain aromatic compounds) and higher functional group density, forming a compact structure, which promotes the second coating layer to have a smaller pore size. The reaction condition is mainly manifested in the reaction temperature. The first temperature is lower, and the reaction rate is slow, so that the first coating layer formed has lower crystallinity and larger pore size. The second temperature is higher, and the reaction rate is fast, so that the organic monomer diffuses more fully and polymerizes more completely, and the second coating layer formed has higher crystallinity and smaller pore size. The assembly mode is manifested in the cooperation of the self-polymerization reaction and the cross-linking reaction. The first coating layer formed by the first polymerization reaction may have skeleton gaps or unreacted sites. The polymerization product of the second polymerization reaction can fill these gaps or combine with the first coating layer through cross-linking reaction, so that the number of functional groups (such as amino groups, aldehyde groups and hydroxyl groups) in a unit volume is increased. The gradient structure of the organic coating layer is constructed by step-by-step assembly. The preparation process is simple, the reaction condition is mild and easy to control, and the gradient structure of the organic coating layer can be accurately controlled to meet different application requirements;

[0073] In some embodiments, the first temperature is 40-60℃, and the reaction time of the first polymerization reaction is 1-3h;

[0074] The second temperature is 60-80℃, and the reaction time of the second polymerization reaction is 2-5h.

[0075] Specifically, the first temperature is lower, the time is shorter, and the reaction rate is slow, so that the first coating layer has lower crystallinity and larger pore size; the second temperature is higher, the time is longer, and the reaction rate is fast, so that the organic monomer diffuses more fully and polymerizes more completely, and the second coating layer has higher crystallinity and smaller pore size.

[0076] In some embodiments, the organic monomer A includes at least one of trimesic aldehyde, pyromellitic dianhydride, terephthaldehyde, 2,5-dimethoxy terephthaldehyde;

[0077] The organic monomer B includes at least one of p-phenylenediamine, tartaric acid dihydrazide, 1,3,5-tris (4-aminophenyl) benzene;

[0078] Specifically, the organic monomer A and the organic monomer B are monomers with large steric hindrance and long chain segments, and specifically, the organic monomer A and the organic monomer B have more benzene rings, longer chain segments and side chains, and the structure is more stretched, which promotes the formation of a first coating layer with a larger pore size.

[0079] In some embodiments, the organic monomer C includes at least one of 2,5-dihydroxy terephthalic acid, 2,5-dihydroxy terephthaldehyde, 2-amino terephthalic acid, 2,5-dicyano terephthaldehyde, tetra (4-formylphenyl) methane, 1,4-benzenediboronic acid, 2,3,6,7,10,11-hexahydroxytriphenylene;

[0080] The organic monomer D includes at least one of ethylenediamine, hexanediamine, 1,3,5-tris (4-aminophenyl) triazine, 4,4', 4''-triaminotriphenylamine, benzidine-3,3', 5,5'-tetramine, hydroquinone, 1,3,5-trihydroxybenzene.

[0081] Specifically, the organic monomer C and the organic monomer D are monomers with small steric hindrance and high functional group density, and specifically, the organic monomer C and the organic monomer D have shorter chain segments and higher functional group density, forming a compact structure, which promotes the second coating layer to have a smaller pore size.

[0082] In some embodiments, the molar ratio of the organic monomer A to the organic monomer B is 1:1 to 1:2.

[0083] Specifically, the molar ratio of the organic monomer A to the organic monomer B includes but is not limited to 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, which promotes the polycondensation reaction of the organic monomer A and the organic monomer B to occur completely.

[0084] In some embodiments, the molar ratio of the organic monomer C to the organic monomer D is 1:1 to 1:1.5.

[0085] Specifically, the molar ratio of the organic monomer C to the organic monomer D includes but is not limited to 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, which facilitates the complete occurrence of the polycondensation reaction between the organic monomers.

[0086] In some embodiments, the catalyst includes at least one of acetic acid, trifluoroacetic acid, p-toluenesulfonic acid, scandium triflate, tris(pentafluorophenyl)borane;

[0087] The promoter includes at least one of piperidine, triethylamine, 1,8-diazabicycloundec-7-ene, 1,4-diazabicyclo[2.2.2]octane, zinc acetate, scandium triflate, tetrabutylammonium bromide.

[0088] Specifically, the catalyst helps to control the reaction rate of the organic monomer A and the organic monomer B, so as to regulate the pore size of the first coating layer; the promoter can improve the reaction rate, and is conducive to the formation of the second coating layer with smaller pore size.

[0089] In some embodiments, the catalyst is used in an amount of 5-15% of the total molar amount of the organic monomer A and the organic monomer B.

[0090] Specifically, the amount of the catalyst helps to control the reaction rate of the organic monomer A and the organic monomer B, so as to regulate the pore size range of the first coating layer.

[0091] In some embodiments, the promoter is used in an amount of 3-8% of the total molar amount of the organic monomer C and the organic monomer D.

[0092] Specifically, the amount of the promoter can regulate the rate of the second polymerization reaction, and is conducive to the formation of the second coating layer with smaller pore size range.

[0093] As known by those skilled in the art, the reaction of each step is a conventional polycondensation reaction, and the specific method and reaction condition are commonly used in the prior art, which will not be described herein.

[0094] The application provides a battery including the negative electrode sheet as described above.

[0095] The application will be further described by the following examples.

[0096] Example 1

[0097] This example is used to illustrate the negative electrode material, the preparation method and the application thereof disclosed by the application.

[0098] 1). Preparation of silicon-carbon particles:

[0099] Porous carbon material was placed in a sintering furnace, and silane gas was introduced into the porous carbon material in an inert atmosphere at 500°C for 10 hours to deposit silicon material. After deposition, the silane gas was switched to acetylene gas, and the temperature was increased to 600°C to coat the surface of the porous carbon material with amorphous carbon, resulting in silicon-carbon particles of 8µm in size, with silicon accounting for 40% by mass and carbon accounting for 60% by mass.

[0100] 2). Preparation of gradient structure organic coating layer:

[0101] Preparation of pre-assembled solution: Trimethylbenzaldehyde (organic monomer A) and p-phenylenediamine (organic monomer B) are mixed in a molar ratio of 1:1.2, and trifluoroacetic acid, accounting for 10% of the total molar amount of organic monomers, is added as a catalyst and dissolved in N,N-dimethylformamide to prepare a pre-assembled solution.

[0102] First coating layer (i.e., first covalent organic framework, hereinafter the same): Silicon carbon particles are added to the pre-assembly solution and stirred at 50℃ (first temperature) for 2 hours to allow organic monomers to be initially assembled on the surface of silicon carbon particles.

[0103] The second coating layer (i.e., the second covalent organic framework, the same below): 2,5-dihydroxyterephthalic acid (organic monomer C) and 1,3,5-tris(4-aminophenyl)triazine (organic monomer D) are added to the above reaction system in a molar ratio of 1:1.2. Then, piperidine, accounting for 5% of the total molar amount of organic monomers C and D, is added as a promoter, and the reaction is continued at 70°C (second temperature) for 3 hours to form an organic coating layer with a gradient structure.

[0104] 3) Post-processing:

[0105] The coated product was centrifuged, washed three times with N,N-dimethylformamide, and then vacuum dried at 70°C for 18 hours to obtain a gradient-structured covalent organic framework compound-coated CVD silicon-carbon material (i.e., anode material). The organic coating thickness was measured to be 200 nm, with a pore size of 10 nm in the first coating layer and 3 nm in the second coating layer; the functional group density of the first coating layer was 7 groups / nm. 2 The functional group density of the second coating layer is 20 per nm. 2 .

[0106] 4) Negative electrode sheet: The negative electrode main material, carbon black, lithium carboxymethyl cellulose (CMC), and polystyrene butadiene (SBR) are mixed evenly in a ratio of 80:10:5:5 and evenly coated on a 10µm copper foil. The mixture is then dried in a vacuum oven at 80℃ for 12 hours to obtain the negative electrode sheet.

[0107] 5). Positive electrode sheet: Lithium cobaltate: carbon black: polyvinylidene fluoride are mixed in a ratio of 80:10:10 and uniformly coated on a 12µm aluminum foil, dried in a vacuum oven at 80°C for 12h to obtain a positive electrode sheet;

[0108] 6). Electrolyte: The electrolyte is 1mol / L lithium hexafluorophosphate (LiPF6) in ethylene carbonate (EC) / diethyl carbonate (DEC) solvent (volume ratio: v / v=1:1)

[0109] 7). Battery:

[0110] The negative electrode sheet, the separator, and the positive electrode sheet are stacked in order to form a battery cell, the battery cell is placed in an aluminum plastic film, electrolyte is injected and packaged, and then the processes of liquid injection, formation, and exhaust are carried out to obtain a lithium ion battery.

[0111] Example 2

[0112] This example is used to illustrate a kind of negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of Example 1, the difference is that:

[0113] 1). Preparation of silicon-carbon particles:

[0114] The porous carbon material is placed in a sintering furnace, and silane gas is introduced into the inert atmosphere at 600°C, and silicon material is deposited in the porous carbon material, and the time is 13h; after the deposition is completed, the silane gas is switched to acetylene gas, and the temperature is increased to 700°C, and amorphous carbon is coated on the surface of the porous carbon material, and 9µm silicon-carbon particles are obtained, in which the mass percentage of silicon is 50%, and the mass percentage of carbon is 50%.

[0115] 2). Preparation of gradient structure organic coating layer:

[0116] Preparation of pre-assembly solution: pyromellitic dianhydride (organic monomer A) and 1,3,5-tris(4-aminophenyl)benzene (organic monomer B) are mixed in a molar ratio of 1:1.5, 12% of p-toluenesulfonic acid is added as a catalyst based on the total molar amount of organic monomers, and is dissolved in dimethyl sulfoxide to prepare a pre-assembly solution.

[0117] First coating layer: silicon-carbon particles are added to the pre-assembly solution, and stirred at 45°C (first temperature) for 2.5h to allow the organic monomers to be initially assembled on the surface of the silicon-carbon particles.

[0118] Second coating layer: 2-amino terephthalic acid (organic monomer C) and hexanediamine (organic monomer D) are added to the above reaction system in a molar ratio of 1:1.3, and 6% of triethylamine is added as a promoter based on the total molar amount of organic monomers C and D, and the reaction is continued at 75°C (second temperature) for 4h to form a gradient structure organic coating layer.

[0119] 3). Post-processing:

[0120] The coated product is centrifuged, washed with dimethyl sulfoxide for 3 times, and then vacuum dried at 75℃ for 20h to obtain a gradient-structure covalent organic framework compound coated CVD silicon-carbon material (i.e. a negative electrode material). It is detected that the thickness of the organic coating layer of the material is 300nm, the pore size of the first coating layer is 12nm, and the pore size of the second coating layer is 2nm; the functional group density of the first coating layer is 6 / nm 2 , and the functional group density of the second coating layer is 22 / nm 2 .

[0121] Example 3

[0122] This example is used to illustrate the negative electrode material and the preparation method and application thereof disclosed by the present application, and most of the operation steps are the same as those of Example 1, and the difference lies in that the organic monomer C is 2,5-dicyano-p-xylylformaldehyde, and the organic monomer D is benzidine-3,3',5,5'-tetraamine.

[0123] Example 4

[0124] This example is used to illustrate the negative electrode material and the preparation method and application thereof disclosed by the present application, and most of the operation steps are the same as those of Example 1, and the difference lies in that the reaction temperature for preparing the first coating layer is 40℃, and the time is 3h; the reaction temperature for preparing the second coating layer is 60℃, and the time is 5h.

[0125] Example 5

[0126] This example is used to illustrate the negative electrode material and the preparation method and application thereof disclosed by the present application, and most of the operation steps are the same as those of Example 1, and the difference lies in that the reaction temperature for preparing the first coating layer is 60℃, and the time is 1h; the reaction temperature for preparing the second coating layer is 80℃, and the time is 2h.

[0127] Example 6

[0128] This example is used to illustrate the negative electrode material and the preparation method and application thereof disclosed by the present application, and most of the operation steps are the same as those of Example 1, and the difference lies in that the reaction temperature for preparing the first coating layer is 30℃, and the time is 4h; the reaction temperature for preparing the second coating layer is 50℃, and the time is 6h.

[0129] Example 7

[0130] This example is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of Example 1, and the difference lies in that the reaction temperature for preparing the first coating layer is 70℃, and the time is 0.5h; the reaction temperature for preparing the second coating layer is 90℃, and the time is 1h.

[0131] Example 8

[0132] This example is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of Example 1, and the difference lies in that the molar ratio of organic monomer A and organic monomer B is 1:1.

[0133] Example 9

[0134] This example is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of Example 1, and the difference lies in that the molar ratio of organic monomer A and organic monomer B is 1:2.

[0135] Example 10

[0136] This example is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of Example 1, and the difference lies in that the molar ratio of organic monomer A and organic monomer B is 1:0.5.

[0137] Example 11

[0138] This example is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of Example 1, and the difference lies in that the molar ratio of organic monomer A and organic monomer B is 1:3.

[0139] Example 12

[0140] This example is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of Example 1, and the difference lies in that the molar ratio of organic monomer C and organic monomer D is 1:1.

[0141] Example 13

[0142] This example is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of Example 1, and the difference lies in that the molar ratio of organic monomer C and organic monomer D is 1:1.5.

[0143] Example 14

[0144] This embodiment is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of embodiment 1, and the difference lies in that the molar ratio of organic monomer C to organic monomer D is 1:0.5.

[0145] Embodiment 15

[0146] This embodiment is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of embodiment 1, and the difference lies in that the molar ratio of organic monomer C to organic monomer D is 1:2.

[0147] Embodiment 16

[0148] This embodiment is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of embodiment 1, and the difference lies in that the amount of catalyst is 5%, and the amount of promoter is 3%.

[0149] Embodiment 17

[0150] This embodiment is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of embodiment 1, and the difference lies in that the amount of catalyst is 15%, and the amount of promoter is 8%.

[0151] Embodiment 18

[0152] This embodiment is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of embodiment 1, and the difference lies in that the amount of catalyst is 2%, and the amount of promoter is 1%.

[0153] Embodiment 19

[0154] This embodiment is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of embodiment 1, and the difference lies in that the amount of catalyst is 18%, and the amount of promoter is 10%.

[0155] Embodiment 20

[0156] This embodiment is used to illustrate the negative electrode material and its preparation method and application disclosed by the present application, and most of the operation steps are the same as those of embodiment 1, and the difference lies in that when preparing the silicon-carbon particles, the mass percentage of silicon is 30%, and the mass percentage of carbon is 70%.

[0157] Embodiment 21

[0158] This embodiment is used to illustrate a negative electrode material disclosed in this invention, its preparation method and application. Most of the operation steps are the same as those in Embodiment 1, except that when preparing silicon-carbon particles, the mass ratio of silicon is 70% and the mass ratio of carbon is 30%.

[0159] Comparative Example 1

[0160] This comparative example is used to illustrate a negative electrode material disclosed in this invention, its preparation method and application. Most of the operation steps are the same as those in Example 1, except that the negative electrode material is silicon-carbon particles without a coating layer.

[0161] Comparative Example 2

[0162] This comparative example is used to illustrate a negative electrode material disclosed in this invention, its preparation method and application. Most of the operation steps are the same as those in Example 1, except that the silicon carbon particles do not contain a second coating layer.

[0163] Comparative Example 3

[0164] This comparative example is used to illustrate a negative electrode material disclosed in this invention, its preparation method and application. Most of the operation steps are the same as those in Example 1, except that the silicon carbon particles do not contain a first coating layer.

[0165] Comparative Example 4

[0166] This comparative example is used to illustrate a negative electrode material disclosed in this invention, its preparation method and application. Most of the operation steps are the same as those in Example 1, except that the outer surface of the silicon carbon particles is a second coating layer, and the first coating layer is disposed on the surface of the second coating layer.

[0167] Silicon carbon particles were added to 2,5-dihydroxyterephthalic acid (organic monomer C) and 1,3,5-tris(4-aminophenyl)triazine (organic monomer D), with a molar ratio of organic monomer C to D of 1:1.2. Piperidine, accounting for 5% of the total molar amount of organic monomers C and D, was then added as a promoter, and the reaction was continued at 70°C for 3 hours. The organic monomers formed a second coating layer on the surface of the silicon carbon particles.

[0168] Add pyromellitic aldehyde (organic monomer A) and p-phenylenediamine (organic monomer B) to the above reaction system. Mix organic monomers A and B in a molar ratio of 1:1.2. Add trifluoroacetic acid, accounting for 10% of the total molar amount of organic monomers, as a catalyst and dissolve it in N,N-dimethylformamide. Then stir the reaction at 50°C for 2 hours to form the first coating layer on the surface of the second coating layer.

[0169] Comparative Example 5

[0170] The comparative example is used to illustrate the negative electrode material, the preparation method and the application thereof disclosed by the present application, and most of the operation steps are the same as those of Example 1, except that the first temperature is 70°C and the second temperature is 50°C. The material is used as a negative electrode material of a lithium ion battery, and is assembled into a lithium ion battery together with a positive electrode material, a separator and an electrolyte to perform performance testing.

[0171] Phenotype testing

[0172] The negative electrode materials obtained in the above examples and comparative examples are tested. High-resolution TEM (HRTEM) can clearly show the interlayer structure of the coating layer, and the size and distribution of the pore diameter can be directly observed. The pore diameter of the first coating layer and the second coating layer is tested by transmission electron microscopy (TEM). The microstructure and pore structure of the coating layer are directly observed by electron beam penetration of the material, and the pore diameter can be quantified by image analysis.

[0173] The functional group density of the first coating layer and the second coating layer is tested by X-ray photoelectron spectroscopy (XPS) and XPS imaging. First, the atomic percentage of the characteristic elements related to the functional groups (such as hydroxyl, carboxyl containing O, amine group containing N, etc.) in the coating layer is determined by XPS full spectrum analysis, and the high-resolution XPS (such as C1s, O1s, N1s spectrum) peak fitting is combined to distinguish the elements in different chemical environments (i.e. corresponding to specific functional groups), calculate the atomic percentage of the elements in the target functional group, and combine the specific surface area of the coating layer (obtained by BET testing) to convert the functional group density (such as “group / nm 2 ”); distinguish the first coating layer and the second coating layer: use the XPS imaging function with a spatial resolution of microns to scan the cross-section or surface of the material, and realize the spatial resolution and quantification of the two coating layers by the difference in the distribution of characteristic elements (the higher the functional group density, the stronger the element signal), so as to calculate the functional group density of each coating layer respectively;

[0174] The thickness of the coating layer is tested by STEM (scanning transmission electron microscopy)-EDS mapping. While observing the morphology, the boundary of the coating layer is confirmed by the distribution of specific elements (such as COF), so as to accurately locate the regions of the first coating layer and the second coating layer, and the thickness of the coating layer can be measured by image analysis. The particle size of the silicon-carbon particles is tested by laser diffraction method (LD), and the specific test results are shown in Table 1.

[0175] Table 1: Phenotype test results of the negative electrode materials prepared in Examples 1-21 and Comparative Examples 1-5

[0176]

[0177] Performance testing

[0178] The negative electrode sheets prepared in the above examples and comparative examples were assembled into lithium ion half-batteries, and were subjected to 0.005 V-2 V charge-discharge test at 25°C at a current density of 0.1 C (1 C = 1800 mAh / g), and the discharge capacity of each cycle was recorded, and the capacity retention rate was calculated.

[0179] Initial discharge specific capacity: can be directly read by the test software Neware tester;

[0180] Negative electrode sheet expansion rate: the thickness of the initial electrode sheet was measured, and the battery cycled for 100 cycles (charged to 2.0 V) was disassembled in a glove box, the thickness of the negative electrode sheet was measured, and the negative electrode sheet expansion rate = (thickness of the electrode sheet after cycling / thickness of the initial electrode sheet) - 1.

[0181] The performance test results of examples 1-21 and comparative examples 1-5 are shown in Table 2.

[0182] Table 2 Performance test results of lithium ion batteries prepared from examples 1-21 and comparative examples 1-5

[0183]

[0184] From the data in Table 1 and Table 2, the results of Examples 1-21 compared with Comparative Example 1 show that when the silicon-carbon particles do not contain a coating layer, the lithium ion transmission efficiency is low, the initial specific discharge capacity of the battery is reduced, the capacity retention rate is reduced to 52%, and the volume expansion of the silicon causes the expansion rate of the negative electrode sheet to greatly increase; the results of Examples 1-21 compared with Comparative Example 2 show that when the silicon-carbon particles do not contain a second coating layer, the over-expansion of the negative electrode sheet cannot be limited, resulting in a high expansion rate of the negative electrode sheet, thereby causing the capacity retention rate to decrease, and due to the low internal conduction efficiency of electrons in the negative electrode material, the initial specific discharge capacity is reduced; the results of Examples 1-21 compared with Comparative Example 3 show that when the silicon-carbon particles do not contain a first coating layer, due to the large functional group density of the second coating layer, although the internal conduction of electrons is improved, the initial specific discharge capacity is higher than that of Comparative Example 2, but the small pore size of the coating layer cannot provide enough space for the volume expansion of the silicon, and the expansion rate of the negative electrode sheet and the capacity retention rate are worse than those of Comparative Example 2; the results of Examples 1-21 compared with Comparative Example 4 show that when the outer surface of the silicon-carbon particles is the second coating layer, i.e., the density of the functional groups decreases in a gradient and the pore size of the porous structure increases in a gradient, the second coating layer cannot provide support for the expansion of the first coating layer, greatly reducing the overall structural stability of the negative electrode material, resulting in an increase in the expansion rate of the negative electrode sheet and a decrease in the capacity retention rate, but since the outer surface of the silicon-carbon particles is the second coating layer, the density of the functional groups is large, so the initial specific discharge capacity is higher than that of Comparative Example 3; the results of Examples 1-21 compared with Comparative Example 5 show that when the first temperature is greater than the second temperature, the reaction rate of the first coating layer is too fast, the pore size is too small, and the space for the volume expansion of the silicon is reduced, while the reaction rate of the second coating layer is relatively slower, the pore size is too large, and the negative electrode material is easily pulverized and detached, increasing the expansion rate of the negative electrode sheet and further causing the capacity retention rate to decrease, but since the pore sizes of the first coating layer and the second coating layer are larger than those of Comparative Example 4, lithium ions can relatively smoothly reach the inside of the particles, so the initial specific discharge capacity is higher than that of Comparative Example 4.

[0185] The results of Examples 1-2, 4-7 show that when the first temperature is in the range of 40-60°C and the reaction time is in the range of 1-3h, the pore size of the first coating layer can be controlled in the range of 5-20nm, and the density of the functional groups is in the range of 5-10 / nm 2When the first temperature is lower than 40℃ and the reaction time is less than 1h, the reaction rate is too slow, which leads to the first coating layer having a too large pore size, the overall structural stability of the negative electrode material being significantly reduced, the expansion rate of the negative electrode sheet being increased, and the capacity retention and the initial specific discharge capacity being further reduced; when the first temperature is greater than 60℃ and the reaction time is greater than 3h, the reaction rate is too fast and lasts too long, which leads to the first coating layer having a too small pore size, the flexibility and deformability being reduced, the expansion rate being sharply increased, and the overall structure of the negative electrode material being prone to collapse, resulting in the capacity retention and the initial specific discharge capacity being rapidly attenuated; when the second temperature is in the range of 60~80℃ and the reaction time is in the range of 2~5h, the pore size of the second coating layer is in the range of 1~5nm, and the functional group density is in the range of 15~25 / nm 2 When the second temperature is lower than 60℃ and the reaction time is less than 2h, the reaction rate is too slow, which leads to the second coating layer having a too large pore size and the effect of relieving the expansion stress being reduced; when the second temperature is greater than 80℃ and the reaction time is greater than 5h, the pore size of the second coating layer is too small, which excessively limits the deformation of the first coating layer, greatly increases the expansion rate, reduces the capacity retention, and decreases the initial specific discharge capacity when the stress range of the second coating layer is exceeded.

[0186] The results of Examples 20~21 compared with Example 1 show that when the mass percentage of silicon in the silicon-carbon particles is in the range of 30~70% and the mass percentage of carbon is in the range of 30~70%, the volume expansion and the electrical conductivity of the negative electrode can be better balanced, thereby improving the cycle performance of the battery.

[0187] The results of Examples 8~15 compared with Example 1 show that when the molar ratio of organic monomer A to organic monomer B is in the range of 1:1~1:2, the polycondensation reaction between organic monomer A and organic monomer B is complete; when the molar ratio exceeds this range, there is an excess of organic monomers, the reaction is incomplete, the excess monomers are prone to block the pore size, the capacity for buffering expansion is reduced, the expansion rate is increased, and the initial specific discharge capacity and the capacity retention are decreased; when the molar ratio of organic monomer C to organic monomer D is in the range of 1:1~1:1.5, the polycondensation reaction between the organic monomers is complete; when the molar ratio exceeds this range, the polycondensation reaction is incomplete, which leads to short molecular chains and poor crystallinity, the complete and long-range ordered covalent organic framework structure cannot be formed, the ion transmission efficiency is seriously affected, the initial specific discharge capacity is reduced, the structure of the second coating layer is loose, the rigidity is reduced, the expansion rate is increased, and the capacity retention is decreased.

[0188] The results of examples 16-19 compared with example 1 show that when the amount of catalyst is in the range of 5-15%, the pore size of the first coating layer can be controlled in the range of 5-20 nm, when the amount of catalyst is less than 5%, the pore size of the first coating layer is too large, when the amount of catalyst is more than 15%, the pore size of the first coating layer is too small, reducing the space for silicon volume expansion, increasing the expansion rate, and the overall structure of the negative electrode material is easy to collapse, resulting in rapid decay of the capacity retention rate and the initial specific discharge capacity; when the amount of accelerator is in the range of 3-8%, the pore size of the second coating layer is in the range of 1-5 nm, when the amount of accelerator is less than 3%, the pore size of the second coating layer is too large, the stress relief effect is reduced, the rigidity is reduced, the expansion rate is increased, and the capacity retention rate is reduced; when the amount of accelerator is more than 8%, the pore size of the second coating layer is too small, the deformation of the first coating layer is excessively limited, and after exceeding the stress range of the second coating layer, the expansion rate is greatly increased, the capacity retention rate is reduced, and the initial specific discharge capacity is reduced.

[0189] The above-described examples are only used to illustrate the technical solutions of the present application, but not limit the same; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalent ones; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A negative electrode material, characterized by, The silicon-carbon particle comprises a silicon-carbon particle and an organic coating layer on the surface of the silicon-carbon particle, the organic coating layer has a porous structure; In the direction away from the surface of the silicon-carbon particle, the density of functional groups in the organic coating layer is overall increased in gradient, and the pore size of the porous structure is overall decreased in gradient; The organic coating layer comprises a first coating layer and a second coating layer, the first coating layer comprises a first covalent organic framework, and the second coating layer comprises a second covalent organic framework, the second covalent organic framework is coated on the surface of the first covalent organic framework; The pore size of the first covalent organic framework is larger than that of the second covalent organic framework, and the density of functional groups in the first covalent organic framework is smaller than that of the second covalent organic framework; The pore size of the first covalent organic framework ranges from 5 to 20 nm, and the pore size of the second covalent organic framework ranges from 1 to 5 nm; the first covalent organic framework has a functional group density of 5-10 per nm 2 the second covalent organic framework has a functional group density of 15-25 per nm 2 .

2. The negative electrode material according to claim 1, characterized in that, The particle size of the silicon-carbon particle ranges from 4 to 20 µm.

3. The negative electrode material of claim 1, wherein, The mass percentage of silicon in the silicon-carbon particle is 30 to 70%, and the mass percentage of carbon is 30 to 70%.

4. The negative electrode material of claim 1, wherein, The thickness of the organic coating layer is 50 to 500 nm.

5. The method of producing a negative electrode material according to any one of claims 1 to 4, wherein The method comprises the following steps: Dissolving organic monomer A, organic monomer B and a catalyst in an organic solvent to prepare a pre-assembly solution; Adding a silicon-carbon particle to the pre-assembly solution to perform a first polymerization reaction at a first temperature, to obtain a first reaction liquid, and a first coating layer is formed on the surface of the silicon-carbon particle in the first reaction liquid; Adding organic monomer C, organic monomer D and a promoter to the first reaction liquid to perform a second polymerization reaction at a second temperature, a second coating layer is formed outside the first coating layer, and a second reaction liquid containing a crude product is obtained; The crude product is sequentially subjected to post-treatment and vacuum drying to obtain a negative electrode material; The first temperature is less than the second temperature; The organic monomer A comprises at least one of an aldehyde compound containing a phenyl group and an acid anhydride compound containing a phenyl group; The organic monomer B comprises an amine compound; The organic monomer C comprises at least one of a carboxylic acid compound, an aldehyde compound, a boric acid compound and a phenol compound; The organic monomer D comprises at least one of an amine compound and a phenol compound.

6. The method of producing a negative electrode material according to claim 5, wherein The first temperature is 40 to 60°C, and the reaction time of the first polymerization reaction is 1 to 3 h; The second temperature is 60 to 80°C, and the reaction time of the second polymerization reaction is 2 to 5 h.

7. The method of claim 5, wherein the method further comprises a step of mixing the carbon material and the metal compound. The organic monomer A comprises at least one of triformylphenyl, pyromellitic dianhydride, terephthaldehyde, 2,5-dimethoxyterephthaldehyde; The organic monomer B comprises at least one of p-phenylenediamine, tartaric acid dihydrazide and 1,3,5-tris(4-aminophenyl)benzene; And / or, the organic monomer C comprises at least one of 2,5-dihydroxyterephthalic acid, 2,5-dihydroxyterephthaldehyde, 2-amino terephthalic acid, 2,5-dicyano terephthaldehyde, tetra(4-formylphenyl)methane, 1,4-benzenediboronic acid and 2,3,6,7,10,11-hexahydroxytriphenylene. The organic monomer D includes at least one of ethylenediamine, hexanediamine, 1,3,5-tris(4-aminophenyl)triazine, 4,4',4''-triaminotriphenylamine, benzidine-3,3',5,5'-tetramine, hydroquinone, 1,3,5-trihydroxybenzene.

8. The method of claim 7, wherein the method further comprises a step of mixing the carbon material and the binder. The molar ratio of the organic monomer A to the organic monomer B is 1:1-1:2; And / or, the molar ratio of the organic monomer C to the organic monomer D is 1:1-1:1.

5.

9. The method of claim 5, wherein the method further comprises a step of mixing the carbon material and the metal compound. The catalyst includes at least one of acetic acid, trifluoroacetic acid, p-toluenesulfonic acid, scandium triflate, tris(pentafluorophenyl)borane; The promoter includes at least one of piperidine, triethylamine, 1,8-diazabicycloundec-7-ene, 1,4-diazabicyclo[2.2.2]octane, zinc acetate, scandium triflate, tetrabutylammonium bromide.

10. The preparation method of the negative electrode material according to claim 9, characterized in that, The amount of the catalyst is 5-15% of the total molar amount of the organic monomer A and the organic monomer B; And / or, the amount of the promoter is 3-8% of the total molar amount of the organic monomer C and the organic monomer D.

11. A negative electrode sheet characterized by comprising: The negative electrode material includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is arranged on at least one side of the negative electrode current collector, and the negative electrode active material layer includes the negative electrode material according to any one of claims 1-4 or is prepared by the preparation method according to any one of claims 5-10.

12. A battery, characterized by The negative electrode sheet includes the negative electrode sheet according to claim 11.

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