CN115101739A - Preparation method of multifunctional silicon carbide carbon negative electrode material and silicon carbon negative electrode material - Google Patents

Preparation method of multifunctional silicon carbide carbon negative electrode material and silicon carbon negative electrode material Download PDF

Info

Publication number
CN115101739A
CN115101739A CN202210882225.9A CN202210882225A CN115101739A CN 115101739 A CN115101739 A CN 115101739A CN 202210882225 A CN202210882225 A CN 202210882225A CN 115101739 A CN115101739 A CN 115101739A
Authority
CN
China
Prior art keywords
carbon
silicon
nano
negative electrode
electrode material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202210882225.9A
Other languages
Chinese (zh)
Inventor
钟宽
詹世英
张正
蒋世用
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gree Altairnano New Energy Inc
Original Assignee
Gree Altairnano New Energy Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gree Altairnano New Energy Inc filed Critical Gree Altairnano New Energy Inc
Priority to CN202210882225.9A priority Critical patent/CN115101739A/en
Publication of CN115101739A publication Critical patent/CN115101739A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes

Abstract

The invention provides a preparation method of a multifunctional silicon carbide carbon negative electrode material and the silicon carbon negative electrode material, wherein the preparation method comprises the following steps: s1, ball-milling micron-sized silicon to be nano-sized by a wet ball-milling method, ball-milling a powdery first carbon precursor to be nano-sized, mixing the two ball-milled slurries with a micron-sized graphite matrix, a nano conductive agent and a binder, uniformly stirring, and performing spray drying to obtain a silicon-carbon composite precursor; and S2, mixing the silicon-carbon composite precursor obtained in the step S1 with the second carbon precursor solution, uniformly stirring, carrying out liquid phase coating, drying, and finally carbonizing, crushing and sieving to obtain the silicon-carbon negative electrode material. The invention has the advantages that: the porous structure, the conductive network and the complete silicon surface carbon coating structure can be formed only by one-time carbonization process, the multifunctional carbonization effect is achieved, the material preparation efficiency is greatly improved, secondary carbon coating is not needed, the operation is easy, large-scale preparation is easy, and the material is high in gram volume and high in first efficiency.

Description

Preparation method of multifunctional silicon carbide carbon negative electrode material and silicon carbon negative electrode material
Technical Field
The invention belongs to the field of electrode materials, and particularly relates to a preparation method of a multifunctional silicon carbide carbon negative electrode material and a silicon carbon negative electrode material.
Background
At present, lithium ion batteries mainly develop towards the direction of high energy density, the current main flow direction is that a high nickel anode is matched with a silicon-based cathode, and the energy density generally reaches 300-400 Wh/kg. The silicon-based material is the next generation lithium ion battery cathode material with the most development potential, and the theoretical specific capacity of the silicon-based material can reach 4200mAh/g and is far higher than the theoretical specific capacity of a graphite cathode by 372 mAh/g; the abundance of silicon on the earth surface is second, and is second to oxygen, so that the resource source is rich; the lithium intercalation potential of silicon is about 0.5V and higher than the lithium precipitation potential, so that lithium is not easy to precipitate, and the safety is facilitated. And the silicon and the oxygen do not generate combustion and gas generation, and the safety is high.
The main problems of the existing silicon-based negative electrode material are large volume change (volume change of about 3 times), poor conductivity and unstable solid-electrolyte interfacial film (SEI film) in the charge and discharge process. In the industry, the performance of the silicon-based negative electrode material is improved mainly by technologies such as nanocrystallization, carbon coating, loading on a carrier with good conductivity, pore forming, pre-lithiation and the like.
For example, patent application CN109638229A provides a core-shell silicon-carbon material, in which the core is a mixed and interwoven structure of nano silicon, carbon nanotubes and graphene, and the shell is coated with carbon. The structure has good conductivity, but the pore structure is limited, no graphite matrix supports the structure, the volume change of the material is obvious during charging and discharging, the gram volume of the silicon-carbon material of the embodiment is high and is between 1700-1800mAh/g, and the first efficiency is not more than 85 percent.
Patent CN110400927A has invented a silicon carbon composite material who contains porous carbon, and whole be the nucleocapsid structure, and the inlayer is nanometer silicon, graphite and porous carbon composition, and the skin is the carbon cladding, and the porous carbon precursor adds for the liquid phase form, and the porous structure that forms after the carbonization is the porous in self structure, and the space that provides for the silicon volume change is limited.
Patent CN112310363A provides a silicon-carbon composite material, in which a carbon precursor is added during the process of ball-milling silicon powder, the obtained slurry is mixed with a graphite matrix, sprayed and carbonized to obtain a structure in which graphite, nano-silicon and amorphous carbon are mixed with each other, and the amorphous carbon has a porous structure; and then carrying out secondary carbon coating. A porous structure of inner amorphous carbon providing space for the volume expansion of silicon; the carbon coating of the outer layer improves the stability of the material. However, the amorphous carbon of the inner layer may have incomplete coating of nano-silicon, and the conductive continuity between nano-silicon is damaged, and the carbon coating of the outer layer adopts solid phase coating, so that the risk of incomplete coating exists.
Disclosure of Invention
Aiming at the problems of limited expansion volume, incomplete coating, low preparation efficiency, low first efficiency and the like of silicon in a silicon-based anode material in the prior art, the invention provides a preparation method of a multifunctional silicon carbide carbon anode material and the silicon carbon anode material.
The technical scheme of the invention is that the preparation method of the multifunctional silicon carbide carbon negative electrode material comprises the following steps:
s1, ball-milling micron-sized silicon to be nano-sized by a wet ball-milling method, ball-milling a powdery first carbon precursor to be nano-sized, mixing the ball-milled silicon slurry and the first carbon precursor slurry with a micron-sized graphite matrix, a nano conductive agent and a binder, uniformly stirring, and spray-drying the mixed slurry to obtain a silicon-carbon composite precursor;
and S2, mixing the silicon-carbon composite precursor obtained in the step S1 with the second carbon precursor solution, uniformly stirring, carrying out liquid phase coating, drying, and finally carbonizing, crushing and sieving to obtain the silicon-carbon negative electrode material.
Further, the particle size of the micron-sized silicon is 1-20 microns, and the particle size of the ball-milled nano-silicon is 10-150 nm; the particle size of the first carbon precursor after ball milling is 10-500 nm; the micron-sized graphite matrix has a particle size of 10-50 μm.
Further, the first carbon precursor is at least one of polyethylene, polypropylene, polystyrene, phenolic resin, urea resin, melamine formaldehyde resin, epoxy resin, asphalt, unsaturated polyester resin and polyurethane.
Further, the second carbon precursor is at least one of citric acid, malic acid, sorbic acid, glucose, sucrose, tartaric acid, polyvinylpyrrolidone, pitch, phenolic resin and epoxy resin.
Further, the solvent for wet ball milling dispersion and the solvent for dissolving the second carbon precursor are at least one of ethanol, acetone, N-methylpyrrolidone, N-dimethylformamide, isopropanol, ethyl acetate, deionized water, toluene, xylene, tetrahydrofuran, and acetonitrile.
Further, the nano conductive agent is at least one of conductive carbon black SP, conductive silver nanoparticles, conductive copper nanoparticles, conductive gold nanoparticles, silver nanowires, copper nanowires, carbon nanotubes, vapor grown carbon fibers, zinc oxide nanorods, silicon carbide nanowires, and boron nitride nanowires.
Further, the graphite matrix is at least one of natural graphite, crystalline flake graphite, artificial graphite and mesocarbon microbeads.
Further, the binder is at least one of polyvinylidene fluoride glue, polyacrylate glue and ethyl cellulose glue.
Further, the silicon carbide negative electrode material comprises the following components in percentage by mass: the ratio of the nano silicon particles to the silicon-graphite is 10-70%; the nano conductive agent accounts for 0.5-15% of the total solid (without the binder and the first carbon precursor) in the step S1; the mass of the first carbon precursor accounts for 5-30% of the total solid (without the binder and the first carbon precursor) in the step S1; the mass of the second carbon precursor solid phase accounts for 5-30% of that of the silicon-carbon composite precursor.
A silicon-carbon negative electrode material comprises a graphite matrix, nano silicon particles, a nano conductive agent, porous nano carbon and a porous amorphous carbon bonding layer; the graphite substrate is arranged in the middle core area, and the porous nano carbon is coated outside the graphite substrate to form a first carbon coating layer; the nano silicon particles, the nano conductive agent and the porous nano carbon are crosslinked and dispersed in the first carbon coating layer and on the surface of the first carbon coating layer in an unordered mode, and the porous amorphous carbon bonding layer is coated on the outer layer of the first carbon coating layer to form a second carbon coating layer.
The invention has the advantages that: through the selection of different grades of particle sizes of silicon, a carbon precursor and graphite, a graphite matrix with a larger volume is positioned in a core area in the preparation process, a porous nano carbon structure is coated outside the graphite matrix, and nano silicon particles and a nano conductive agent are distributed in the porous nano carbon structure, so that the structural stability of the whole silicon-carbon negative electrode material is improved; the porous nano carbon structure and the amorphous carbon adhesive layer form a double-layer carbon coating structure to form complete carbon coating on the nano silicon particles, so that sufficient space is reserved for volume expansion of silicon, the crushing of a negative electrode material is avoided, the influence of electrolyte on a silicon-based material is reduced, and the stability of the material is facilitated; the porous nano carbon structure, the nano conductive agent, the nano silicon particles and the porous amorphous carbon adhesive layer form a continuous conductive network, so that the conductivity of the silicon-based material is improved.
According to the invention, a porous structure, a conductive network and a double-layer carbon coating structure can be formed only by one carbonization process, the silicon coating is more complete, the multifunctional carbonization effect is achieved, the material preparation efficiency is greatly improved, secondary carbon coating is not needed, the preparation cost is reduced, the operation is easy, and the large-scale preparation is easy; and the material has high gram volume and first efficiency.
Drawings
FIG. 1 is a schematic structural view of a multifunctional SiC carbon material;
FIG. 2 is a low magnification SEM image of a sample after carbonization according to example 1;
FIG. 3 is a high magnification SEM image of a sample after carbonization in example 1.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The one-step silicon carbide carbon negative electrode material provided by the invention, as shown in fig. 1, comprises the following structure: graphite matrix 1, nano-silicon particles 2, nano-conductive agent 3, porous nano-carbon 4 and porous amorphous carbon adhesive layer 5. The graphite matrix 1 is arranged in a central core area, and the porous nanocarbon 4 is coated outside the graphite matrix 1 to form a first carbon coating layer; the nano silicon particles 2 and the nano conductive agent 3 are crosslinked with the porous nano carbon 4, and are dispersed in the first carbon coating layer formed by the porous nano carbon 4 in an unordered manner, and the porous amorphous carbon adhesive layer 5 is arranged on the outer layer of the first carbon coating layer to form a second carbon coating layer, so that the second carbon coating layer is coated on the outer layer of the porous nano carbon 4, and meanwhile, the nano silicon particles 2 are completely coated.
The preparation method of the silicon carbide negative electrode material specifically comprises the following steps:
s1, ball-milling micron-sized silicon to be nano-sized by a wet ball-milling method, ball-milling a powdery first carbon precursor to be nano-sized, mixing the ball-milled silicon slurry and the first carbon precursor slurry with a micron-sized graphite matrix, a nano conductive agent and a binder, uniformly stirring, and spray-drying the mixed slurry to obtain a silicon-carbon composite precursor;
and S2, mixing the silicon-carbon composite precursor obtained in the step S1 with the second carbon precursor solution, uniformly stirring, carrying out liquid phase coating, drying, and finally carbonizing, crushing and sieving to obtain the silicon-carbon negative electrode material.
Under the condition that the ball-milled first carbon precursor exists in the nano silicon particles 2 and the nano conductive agent 3, the first carbon precursor is carbonized to mainly form a porous nano carbon structure 4 which is crosslinked with the nano silicon particles 2 and the nano conductive agent 3 and is adsorbed on the outer layer of the micron-sized graphite matrix 1.
The second carbon precursor is dissolved in the solution to coat the silicon-carbon precursor mixed in the step S1, and the carbonized silicon-carbon precursor is simultaneously coated on the surfaces of the nano silicon particles 2, the nano conductive agent 3 and the porous nano carbon 4.
The particle size of the micron-sized silicon is generally 1-20 mu m, and the particle size of the ball-milled nano-silicon is 10-150 nm; the grain diameter of the nano first powdery carbon precursor after ball milling is 10-500 nm; the particle size of the micron-sized graphite particles is 10-50 mu m.
The first carbon precursor is at least one of polyethylene, polypropylene, polystyrene, phenolic resin, urea-formaldehyde resin, melamine formaldehyde resin (MRF), epoxy resin, asphalt, unsaturated polyester resin, polyurethane and the like.
The second carbon precursor is at least one of citric acid, malic acid, sorbic acid, glucose, sucrose, tartaric acid, polyvinylpyrrolidone, asphalt, phenolic resin, epoxy resin and the like.
The solvent for wet ball milling dispersion and the solvent for dissolving the second carbon precursor are at least one of ethanol, acetone, N-methylpyrrolidone (NMP), N-Dimethylformamide (DMF), isopropanol, ethyl acetate, deionized water, toluene, xylene, tetrahydrofuran, acetonitrile and the like.
The nano conductive agent is at least one of conductive carbon black SP, conductive silver nanoparticles, conductive copper nanoparticles, conductive gold nanoparticles, silver nanowires, copper nanowires, Carbon Nanotubes (CNT), Vapor Grown Carbon Fibers (VGCF), zinc oxide (ZnO) nanorods, silicon carbide (SiC) nanowires, Boron Nitride (BN) nanowires, and the like.
The graphite matrix is at least one of natural graphite, crystalline flake graphite, artificial graphite, mesocarbon microbeads and the like.
The binder is at least one of polyvinylidene fluoride (PVDF) glue, Polyacrylate (PAA) glue, ethyl cellulose glue and the like.
The silicon carbide negative electrode material comprises the following components in percentage by mass: the nano silicon particles account for 10-70% of the silicon-graphite in the step S1; the nano conductive agent accounts for 0.5-15% of the total solid (without the binder and the first carbon precursor) in the step S1; the first carbon precursor accounts for 5-30% of the total solid (without the binder and the first carbon precursor) in the step S1. The mass of the second carbon precursor solid phase accounts for 5-30% of the mass of the silicon-carbon precursor spray powder.
The preparation process and technical effects of the present invention are specifically illustrated by several sets of examples below.
Example 1
The preparation method comprises the following steps of preparing a negative silicon-based material by using asphalt as a first carbon precursor, phenolic resin as a second carbon precursor, artificial graphite as a graphite matrix, conductive carbon black SP as a nano conductive agent, NMP as a wet ball milling dispersion solvent and acetone as a second carbon precursor solvent, wherein the preparation process comprises the following steps:
step S1:
s11, adding 1000g of silicon powder with the particle size of D50 being 5 microns into 2000g of NMP solvent, pre-stirring to wet the silicon powder by primary mixing in NMP, adding the wet silicon powder into a ball milling tank (containing zirconia balls with the diameter of 0.3 mm), and ball milling for 24 hours at the ball milling speed of 1500r/min to obtain the nano silicon slurry with the particle size of D50 being 105 nm.
S12, 344g of millimeter-sized blocky asphalt is weighed, is manually ground and crushed by a mortar, is added into a ball milling tank (containing zirconia balls with the diameter of 1 mm), and is added with 1947g of NMP solvent to be ball-milled for 8 hours at the ball milling speed of 1000r/min, so that asphalt particles with the D50 particle size of 160nm are obtained.
S13, adding the nano silicon slurry and the asphalt slurry into a dispersion grinding tank, and pre-stirring uniformly.
S14, adding 51.5g of conductive carbon black SP into a dispersion grinding tank, mixing with the slurry in the tank, and pre-stirring uniformly; 51.5g of PVDF gel was dissolved in 2238g of NMP, and the resulting solution was charged into a dispersion mill pot, and stirred with the slurry in the pot.
S15, 667g of artificial graphite with D50 of 10 μm is added into the dispersion grinding tank and stirred with the materials in the tank.
In the slurry, the weight ratio of silicon to graphite is 60%, the conductive nanoparticles SP account for 3% of the total solid (without PVDF gum and asphalt), the amount of asphalt accounts for 20% of the total solid (without PVDF gum and asphalt), the amount of gum accounts for 3% of the total solid (without PVDF gum and asphalt), and the total solid content of the slurry is 25%.
And S16, grinding and dispersing, wherein the grinding rotation speed is 2000r/min, and the grinding time is 5 h.
And S17, after grinding, carrying out spray drying to obtain the silicon-carbon composite precursor.
And then, performing carbon coating on the sprayed powder by adopting a liquid phase coating method in the step S2. The specific method comprises the following steps:
s21, weighing 150g of phenolic resin powder, dissolving the phenolic resin powder into 1500g of acetone solvent, adding 1000g of the silicon-carbon composite precursor obtained in the step S1 into the phenolic resin solution, and uniformly stirring under vacuum to obtain slurry. (the ratio of the second carbon precursor to the silicon-carbon composite precursor was 15%)
S22, baking for 4 hours at 70 ℃ in vacuum, and carrying out carbonization treatment; carbonizing under the atmosphere of inert gas nitrogen, wherein the nitrogen flow is 2L/min, the temperature is raised to 350 ℃ at the heating rate of 3 ℃/min, and the temperature is kept for 2 h; then heating to 800 ℃ at the heating rate of 2 ℃/min, carbonizing for 3h, naturally cooling to below 100 ℃, and taking out the sample.
And S23, crushing the sample, and sieving with a 400-mesh sieve to obtain the silicon-carbon negative electrode material.
As shown in fig. 2 and 3, it can be seen that the porous nanocarbon structure 4 formed by carbonizing the first carbon precursor and the porous amorphous carbon adhesion layer 5 formed by carbonizing the second carbon precursor form a complete carbon coating on the surface of the nano silicon particle 2, so that sufficient space is reserved for the volume expansion of silicon, and the material is prevented from being broken; the complete carbon coating is also beneficial to reducing the influence of electrolyte on the nano silicon particles 2, and the porous carbon nano structure 4 and the porous amorphous carbon bonding layer 5 form a porous carbon structure coated on the graphite matrix 1 with insignificant volume expansion, thereby being beneficial to the structural stability of the cathode material; the nano silicon particles 2, the nano conductive agent 3, the porous nano carbon 4 and the porous amorphous carbon adhesive layer 5 are crosslinked together to form a reticular conductive structure together, which is beneficial to the conductivity of the silicon-based negative electrode material.
Example 2
The preparation method comprises the following steps of preparing a negative silicon-based material by using polyethylene as a first carbon precursor, epoxy resin as a second carbon precursor, crystalline flake graphite as a graphite matrix, BN nanowire as a nano conductive agent, PAA (polyamide acid) glue as a binder, ethyl acetate as a wet ball milling dispersion solvent, and tetrahydrofuran as a second carbon precursor solvent, wherein the preparation process comprises the following steps:
step S1:
s11, adding 1000g of silicon powder with the particle size of D50 being 2 microns into 2500g of ethyl acetate solvent, pre-stirring to wet the silicon powder by primary mixing in ethyl acetate, adding the mixture into a ball milling tank (containing zirconia balls with the diameter of 0.3 mm), and carrying out ball milling for 12 hours at the ball milling speed of 1500r/min to obtain the silicon nano-slurry with the particle size of D50 being 95 nm.
S12, weighing 526g of millimeter-sized bulk polyethylene, manually grinding and crushing the polyethylene by using a mortar, adding the ground polyethylene into a ball milling tank (containing zirconia balls with the diameter of 1 mm), adding 4737g of ethyl acetate solvent, and carrying out ball milling for 8 hours at the ball milling speed of 1000r/min to obtain polyethylene particles with the D50 particle size of 130 nm.
S13, adding the nano silicon slurry and the polyethylene slurry into a dispersion grinding tank, and pre-stirring uniformly.
S14, adding 105g of BN nanowire into the dispersion grinding tank, mixing with the slurry in the tank, and pre-stirring uniformly; 168g of PAA gum is dissolved in 2093g of ethyl acetate, added into a dispersion grinding tank and stirred with the slurry in the tank uniformly.
S15, 1000g of flake graphite with the D50 of 15 μm is added into a dispersion grinding tank and is stirred with the materials in the tank uniformly.
In the above slurry, the weight ratio of silicon to graphite is 50%, BN nanowires account for 5% of the total solids (without PAA gum and polyethylene), polyethylene accounts for 25% of the total solids (without PAA gum and polyethylene), PAA gum accounts for 8% of the total solids (without PAA gum and polyethylene), and the total solid content of the slurry is 22%.
And S16, grinding and dispersing, wherein the grinding rotation speed is 2000r/min, and the grinding time is 5 h.
And S17, after grinding, carrying out spray drying to obtain the silicon-carbon composite precursor.
And then, performing carbon coating on the sprayed powder by adopting a liquid phase coating method in the step S2. The specific method comprises the following steps:
s21, weighing 150g of epoxy resin powder, dissolving the epoxy resin powder into 1500g of tetrahydrofuran solvent, adding 1000g of the silicon-carbon composite precursor obtained in the step S1 into the epoxy resin solution, and uniformly stirring under vacuum to obtain slurry. (the ratio of the second carbon precursor to the silicon-carbon composite precursor was 15%)
S22, baking at 60 ℃ for 4h in vacuum, and carrying out carbonization treatment; carbonizing under the atmosphere of inert gas nitrogen, wherein the nitrogen flow is 2L/min, the temperature is raised to 250 ℃ at the temperature raising rate of 3 ℃/min, and the temperature is kept for 2 h; then heating to 800 ℃ at the heating rate of 2 ℃/min, carbonizing for 3h, naturally cooling to below 100 ℃, and taking out the sample.
And S23, crushing the sample, and sieving the sample with a 400-mesh sieve to obtain the silicon-carbon negative electrode material.
After liquid phase coating and carbonization, uniformly covering carbon coating layers obtained by carbonizing epoxy resin on the surfaces of the silicon nanoparticles, the porous carbon and the BN nanowires to form a conductive network structure.
Example 3
The preparation method comprises the following steps of preparing a negative silicon-based material by using polyurethane as a first carbon precursor, phenolic resin as a second carbon precursor, artificial graphite as a graphite matrix, silver nanowires as a nano conductive agent, ethyl cellulose gum as a binder, isopropanol as a wet ball milling dispersion solvent and ethanol as a second carbon precursor solvent, wherein the preparation process comprises the following steps:
step S1:
s11, adding 1000g of silicon powder with the particle size of D50 being 3 microns into 2500g of isopropanol solvent, pre-stirring to wet the silicon powder by primary mixing in the isopropanol, adding the mixture into a ball milling tank (containing zirconia balls with the diameter of 0.3 mm), and carrying out ball milling for 16 hours at the ball milling speed of 1500r/min to obtain the nano silicon slurry with the particle size of D50 being 110 nm.
S12, weighing 417g of millimeter-sized blocky polyurethane, manually grinding and crushing the materials by using a mortar, adding the materials into a ball milling tank (containing zirconia balls with the diameter of 1 mm), adding 3056g of isopropanol solvent, and carrying out ball milling for 12 hours at the ball milling speed of 1000r/min to obtain polyurethane particles with the D50 particle size of 120 nm.
S13, adding the nano silicon slurry and the polyurethane slurry into a dispersion grinding tank, and pre-stirring uniformly.
S14, adding 278g of silver nanowires into the dispersion grinding tank, mixing with the slurry in the tank, and pre-stirring uniformly; 194g of ethyl cellulose gum was dissolved in 1898g of isopropyl alcohol, added to a dispersion mill tank, and stirred uniformly with the slurry in the tank.
S15, 1500g of artificial graphite with D50 of 16 μm is added into a dispersion grinding tank and stirred with the materials in the tank uniformly.
In the slurry, the weight ratio of silicon to silicon-graphite is 40%, the silver nanowires account for 10% of the total solids (without ethyl cellulose gum and polyurethane), the polyurethane accounts for 15% of the total solids (without ethyl cellulose gum and polyurethane), the ethyl cellulose gum accounts for 7% of the total solids (without ethyl cellulose gum and polyurethane), and the total solid content of the slurry is 30%.
And S16, grinding and dispersing, wherein the grinding rotation speed is 2000r/min, and the grinding time is 5 h.
And S17, after grinding, carrying out spray drying to obtain the silicon-carbon composite precursor.
And then carrying out carbon coating on the sprayed powder by adopting a liquid phase coating method in the step S2. The specific method comprises the following steps:
s21, weighing 150g of phenolic resin powder, dissolving the phenolic resin powder in 1500g of ethanol solvent, adding 1000g of the silicon-carbon composite precursor obtained in the step S1 into the phenolic resin solution, and uniformly stirring under vacuum to obtain slurry. (the ratio of the second carbon precursor to the silicon-carbon composite precursor was 15%)
S22, baking for 4 hours in vacuum at 60 ℃ and carrying out carbonization treatment; carbonizing under the atmosphere of inert gas nitrogen, wherein the nitrogen flow is 2L/min, the temperature is increased to 300 ℃ at the heating rate of 3 ℃/min, and the temperature is kept for 2 h; then heating to 800 ℃ at the heating rate of 2 ℃/min, carbonizing for 3h, naturally cooling to below 100 ℃, and taking out the sample.
And S23, crushing the sample, and sieving the sample with a 400-mesh sieve to obtain the silicon-carbon negative electrode material.
Comparative example 1
To examine the effect of the liquid phase coating of step S2 on the properties of the silicon carbon material, the following comparative experiment was performed.
The spray-dried silicon-carbon composite precursor obtained in step S1 of example 1 was carbonized without being coated with a liquid phase. The carbonization process is carried out in the atmosphere of inert gas nitrogen, the nitrogen flow is 2L/min, the temperature is raised to 350 ℃ at the heating rate of 3 ℃/min, and the temperature is kept for 2 h; then heating to 800 ℃ at the heating rate of 2 ℃/min, carbonizing for 3h, naturally cooling to below 100 ℃, and taking out the sample.
And crushing the sample, and sieving the crushed sample with a 400-mesh sieve to obtain the silicon-carbon negative electrode material.
Comparative example 2
In order to examine the influence of the porous nano carbon structure on the material performance, the silicon-carbon composite material without the porous nano carbon structure is prepared; compared with example 1, in the grinding and dispersing process, no asphalt slurry is added, and other preparation processes are the same. The preparation process comprises the following steps:
step S1:
s11, adding 1000g of silicon powder with the particle size of D50 being 5 microns into 2000g of NMP solvent, pre-stirring to wet the silicon powder by primary mixing in NMP, adding the wet silicon powder into a ball milling tank (containing zirconia balls with the diameter of 0.3 mm), and ball milling for 24 hours at the ball milling speed of 1500r/min to obtain the nano silicon slurry with the particle size of D50 being 105 nm.
S12, adding the nano silicon slurry into a dispersion grinding tank, adding 51.5g of conductive carbon black SP, mixing with the slurry in the tank, and pre-stirring uniformly; 51.5g of PVDF gel was dissolved in 2238g of NMP, and the solution was added to a dispersion grinding tank and stirred with the slurry in the tank.
S13, 667g of artificial graphite with D50 of 10 μm is added into the dispersion grinding tank and stirred with the materials in the tank uniformly.
In the slurry, the weight ratio of silicon to silicon-graphite is 60%, the conductive nanoparticles SP account for 3% of the total solids (without PVDF gum and asphalt), the gum accounts for 3% of the total solids (without PVDF gum and asphalt), and the total solid content of the slurry is 35%.
And S14, grinding and dispersing, wherein the grinding rotation speed is 2000r/min, and the grinding time is 5 h.
And S15, after grinding, carrying out spray drying to obtain the silicon composite precursor.
And then, performing carbon coating on the sprayed powder by adopting a liquid phase coating method in the step S2. The specific method comprises the following steps:
s21, weighing 150g of phenolic resin powder, dissolving the phenolic resin powder in 1500g of acetone solvent, adding 1000g of the silicon composite precursor obtained in the step S1 into the phenolic resin solution, and uniformly stirring under vacuum to obtain slurry.
S22, baking for 4 hours at 70 ℃ in vacuum, and carrying out carbonization treatment; carbonizing under the atmosphere of inert gas nitrogen, wherein the nitrogen flow is 2L/min, the temperature is raised to 350 ℃ at the temperature raising rate of 3 ℃/min, and the temperature is kept for 2 h; then heating to 800 ℃ at the heating rate of 2 ℃/min, carbonizing for 3h, naturally cooling to below 100 ℃, and taking out the sample.
And S23, crushing the sample, and sieving with a 400-mesh sieve to obtain the silicon-carbon negative electrode material.
Comparative example 3
In order to investigate the influence of the nano conductive agent on the performance of the silicon-carbon material, a comparative example without adding the nano conductive agent was performed. The specific procedure was as in example 3 except that silver nanowires were not added.
The silicon-carbon negative electrode materials obtained in the above examples 1 to 3 and comparative examples 1 to 3 were subjected to a charging half cell test, and the test results are shown in table 1.
TABLE 1 Electricity-on half-cell test results for silicon carbon negative electrode materials
Silicon-carbon negative electrode material sample Gram volume mAh/g The highest first efficiency%
Example 1 1542 90.3
Example 2 1253 91.4
Example 3 986 92.4
Comparative example 1 1436 83.5
Comparative example 2 1612 85.3
Comparative example 3 975 87.5
The test result shows that: the porous silicon-carbon cathode material prepared by the method has high first efficiency which breaks through 90%, the gram capacity of the half cell is influenced by the proportion of silicon, and the lower the silicon content is, the smaller the gram capacity is.
In comparative example 1, the outermost porous amorphous carbon adhesion layer formed by liquid phase coating is omitted, so that the surface of part of silicon nanoparticles is not coated and protected, the conductivity of the material is reduced, and the gram volume and the first efficiency of the silicon-carbon negative electrode material are reduced.
The gram volume of the comparative example 2 is slightly higher than that of the example 1, because the first carbon precursor is not added, the silicon proportion of the whole material is improved, but a porous nano carbon structure formed by the first carbon precursor is lacked, so that the expansion space reserved for the nano silicon particles is insufficient, the surface of the silicon-carbon negative electrode material has a crushing phenomenon, and the stability of the material is reduced; and due to the lack of a porous nano carbon structure, an effective conductive network cannot be formed in the silicon-carbon negative electrode material, so that the conductivity of the silicon-carbon negative electrode material is reduced.
Compared with the embodiment 3, the first efficiency is reduced and the gram-capacitance is not increased because the nano conductive agent is not added, the conductivity between the nano silicon and the porous nano carbon structure is reduced, the conductive capability of a conductive network is weakened, and the gram-capacitance and the first efficiency are reduced.
From the above examples and comparative examples it can be seen that: through the one-step carbonization process, multiple effects of a carbon porous structure, carbon coating on the surface of the nano silicon and formation of a conductive network can be simultaneously realized on the graphite substrate, the porous structure can accommodate volume changes of silicon nano particles in charging and discharging, and the overall structural stability of the material is improved. The carbon coating layer on the surface of the nano silicon reduces the contact between silicon and electrolyte and improves the performance stability of the material. The conductive network formed by the porous carbon structure, the nano conductive agent and the carbon coated on the silicon surface improves the conductivity of the silicon-carbon composite material and promotes the first effect and the capacity. The preparation method of the silicon-based composite material is simple, feasible, effective and easy for large-scale preparation.
Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

1. The preparation method of the multifunctional silicon carbide carbon negative electrode material is characterized by comprising the following steps of:
s1, ball-milling micron-sized silicon to be nano-sized by a wet ball-milling method, ball-milling a powdery first carbon precursor to be nano-sized, mixing the ball-milled silicon slurry and the first carbon precursor slurry with a micron-sized graphite matrix, a nano conductive agent and a binder, uniformly stirring, and spray-drying the mixed slurry to obtain a silicon-carbon composite precursor;
and S2, mixing the silicon-carbon composite precursor obtained in the step S1 with the second carbon precursor solution, stirring uniformly, carrying out liquid phase coating, drying, and finally carbonizing, crushing and sieving to obtain the silicon-carbon negative electrode material.
2. The method for preparing the multifunctional silicon carbide carbon negative electrode material according to claim 1, wherein the method comprises the following steps: the particle size of the micron-sized silicon is 1-20 mu m, and the particle size of the ball-milled nano-silicon is 10-150 nm; the particle size of the first carbon precursor after ball milling is 10-500 nm; the micron-sized graphite matrix has a particle size of 10-50 μm.
3. The method for preparing the multifunctional silicon carbide carbon negative electrode material according to claim 1, wherein the method comprises the following steps: the first carbon precursor is at least one of polyethylene, polypropylene, polystyrene, phenolic resin, urea-formaldehyde resin, melamine-formaldehyde resin, epoxy resin, asphalt, unsaturated polyester resin and polyurethane.
4. The method for preparing the multifunctional silicon carbide carbon negative electrode material according to claim 1, wherein the method comprises the following steps: the second carbon precursor is at least one of citric acid, malic acid, sorbic acid, glucose, sucrose, tartaric acid, polyvinylpyrrolidone, asphalt, phenolic resin and epoxy resin.
5. The method for preparing the multifunctional silicon carbide carbon negative electrode material according to claim 1, characterized in that: the solvent for wet ball milling dispersion and the solvent for dissolving the second carbon precursor are at least one of ethanol, acetone, N-methyl pyrrolidone, N-dimethylformamide, isopropanol, ethyl acetate, deionized water, toluene, xylene, tetrahydrofuran and acetonitrile.
6. The method for preparing the multifunctional silicon carbide carbon negative electrode material according to claim 1, wherein the method comprises the following steps: the nano conductive agent is at least one of conductive carbon black SP, conductive silver nanoparticles, conductive copper nanoparticles, conductive gold nanoparticles, silver nanowires, copper nanowires, carbon nanotubes, vapor grown carbon fibers, zinc oxide nanorods, silicon carbide nanowires and boron nitride nanowires.
7. The method for preparing the multifunctional silicon carbide carbon negative electrode material according to claim 1, wherein the method comprises the following steps: the graphite matrix is at least one of natural graphite, crystalline flake graphite, artificial graphite and mesocarbon microbeads.
8. The method for preparing the multifunctional silicon carbide carbon negative electrode material according to claim 1, wherein the binder is at least one of polyvinylidene fluoride glue, polyacrylate glue and ethyl cellulose glue.
9. The preparation method of the multifunctional silicon carbide carbon negative electrode material as claimed in any one of claims 1 to 8, wherein the ratio of the components of the silicon carbide negative electrode material is as follows by mass: the ratio of the nano silicon particles to the silicon-graphite is 10-70%; the nano conductive agent accounts for 0.5-15% of the total solid (without the binder and the first carbon precursor) in the step S1; the mass of the first carbon precursor accounts for 5-30% of the total solid (without the binder and the first carbon precursor) in the step S1; the mass of the second carbon precursor solid phase accounts for 5-30% of that of the silicon-carbon composite precursor.
10. A silicon-carbon negative electrode material is characterized in that: comprises a graphite substrate, nano silicon particles, a nano conductive agent, porous nano carbon and a porous amorphous carbon adhesive layer; the graphite substrate is arranged in the middle core area, and the porous nano carbon is coated outside the graphite substrate to form a first carbon coating layer; the nano silicon particles, the nano conductive agent and the porous nano carbon are crosslinked and dispersed in the first carbon coating layer and on the surface in an unordered mode, and the porous amorphous carbon bonding layer is coated on the outer layer of the first carbon coating layer to form a second carbon coating layer.
CN202210882225.9A 2022-07-26 2022-07-26 Preparation method of multifunctional silicon carbide carbon negative electrode material and silicon carbon negative electrode material Pending CN115101739A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210882225.9A CN115101739A (en) 2022-07-26 2022-07-26 Preparation method of multifunctional silicon carbide carbon negative electrode material and silicon carbon negative electrode material

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210882225.9A CN115101739A (en) 2022-07-26 2022-07-26 Preparation method of multifunctional silicon carbide carbon negative electrode material and silicon carbon negative electrode material

Publications (1)

Publication Number Publication Date
CN115101739A true CN115101739A (en) 2022-09-23

Family

ID=83298188

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210882225.9A Pending CN115101739A (en) 2022-07-26 2022-07-26 Preparation method of multifunctional silicon carbide carbon negative electrode material and silicon carbon negative electrode material

Country Status (1)

Country Link
CN (1) CN115101739A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115275176A (en) * 2022-09-30 2022-11-01 河北格力钛新能源有限公司 Preparation method of silicon-carbon composite material and lithium battery
CN116259738A (en) * 2023-05-15 2023-06-13 深圳索理德新材料科技有限公司 Nano silicon-carbon composite negative electrode material, preparation method and lithium ion battery

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115275176A (en) * 2022-09-30 2022-11-01 河北格力钛新能源有限公司 Preparation method of silicon-carbon composite material and lithium battery
CN115275176B (en) * 2022-09-30 2023-03-07 河北格力钛新能源有限公司 Preparation method of silicon-carbon composite material and lithium battery
CN116259738A (en) * 2023-05-15 2023-06-13 深圳索理德新材料科技有限公司 Nano silicon-carbon composite negative electrode material, preparation method and lithium ion battery
CN116259738B (en) * 2023-05-15 2023-08-11 深圳索理德新材料科技有限公司 Nano silicon-carbon composite negative electrode material, preparation method and lithium ion battery

Similar Documents

Publication Publication Date Title
CN102479948B (en) Negative active core-shell material of a kind of lithium ion battery and preparation method thereof and a kind of lithium ion battery
CN107845797B (en) Nano silicon-carbon composite negative electrode material for lithium ion battery and preparation method thereof
CN115101739A (en) Preparation method of multifunctional silicon carbide carbon negative electrode material and silicon carbon negative electrode material
CN110112408B (en) Graphene-silicon composite material, preparation method thereof, electrode material and battery
CN102479949A (en) Anode active material of lithium ion battery, preparation method thereof and lithium ion battery
CN108172770B (en) Carbon-coated NiP with monodisperse structural featuresxNano composite electrode material and preparation method thereof
WO2022121281A1 (en) Self-filling coated silicon-based composite material and preparation method therefor and application thereof
WO2019019410A1 (en) Modified lithium-free anode, method for preparing same, and lithium-ion battery comprising same
CN113659125B (en) Silicon-carbon composite material and preparation method thereof
WO2013133040A1 (en) Positive electrode for lithium ion secondary battery, lithium ion secondary battery, and battery module
CN112234182B (en) High-capacity silicon-carbon material for lithium battery cathode and preparation method thereof
CN115275176B (en) Preparation method of silicon-carbon composite material and lithium battery
WO2016110108A1 (en) Method of preparing plasma spraying for nanoscale lithium-ion composite positive electrode
CN102263245A (en) Method for preparing composite cathode material of spherical porous lithium ion battery
CN114447305A (en) Multi-element carbon-based rapid-charging negative electrode composite material and preparation method thereof
CN111668474A (en) Negative electrode material, preparation method thereof and secondary battery
WO2024031867A1 (en) Nitrogen-doped graphene-coated silicon-carbon composite material, and preparation method therefor and use thereof
WO2021143515A1 (en) Polyamine composite material and preparation method therefor, slurry containing polyamine composite material, separator, electrode sheet, and lithium-sulfur battery
WO2023173772A1 (en) Preparation method for and use of hard carbon negative electrode material
CN113206249A (en) Lithium battery silicon-oxygen composite negative electrode material with good electrochemical performance and preparation method thereof
CN112768671A (en) Preparation method of silicon-carbon composite negative electrode material and negative electrode material prepared by preparation method
CN110098402B (en) Silicon-carbon negative electrode material for lithium ion battery and preparation method thereof
CN115275191A (en) Negative electrode material, negative plate and sodium ion battery
CN115132982A (en) Preparation method of silicon-based negative electrode material
CN114843482A (en) Core-shell silicon-carbon composite material and preparation method and application thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication