CN111785945A - Graphene-coated nano silicon and preparation method thereof, silicon-carbon negative electrode material and preparation method thereof - Google Patents

Graphene-coated nano silicon and preparation method thereof, silicon-carbon negative electrode material and preparation method thereof Download PDF

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CN111785945A
CN111785945A CN202010707824.8A CN202010707824A CN111785945A CN 111785945 A CN111785945 A CN 111785945A CN 202010707824 A CN202010707824 A CN 202010707824A CN 111785945 A CN111785945 A CN 111785945A
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silicon
graphene
nano silicon
gas
preparation
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李能
王志勇
皮涛
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Hunan Shinzoom Technology Co ltd
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Hunan Shinzoom Technology Co ltd
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    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The application relates to the field of materials, in particular to graphene-coated nano silicon and a preparation method thereof, and a silicon-carbon negative electrode material and a preparation method thereof. The gas phase reaction equipment is provided with a high-temperature area and a low-temperature area; the method for coating nano silicon by graphene comprises the following steps: preparing nano silicon by reacting a carrier gas carrying silicon material in a high-temperature region, introducing a reaction gas into a low-temperature region by the carrier gas carrying the nano silicon to form a graphene layer on the surface of the nano silicon; in the process, the nano silicon is hardly agglomerated, the silicon crystal particles are prevented from being large in size, the nano silicon has high activity, in-situ coating can be carried out in a low-temperature region, graphene is uniformly loaded on the surface of the nano silicon to obtain graphene-coated nano silicon, and excessive nano silicon is prevented from being exposed on the surface, so that the problem of circulating water jump caused by consumption of electrolyte in the charging and discharging process is solved. The graphene-coated nano silicon obtained by the method can also effectively inhibit the volume expansion of the nano silicon.

Description

Graphene-coated nano silicon and preparation method thereof, silicon-carbon negative electrode material and preparation method thereof
Technical Field
The application relates to the field of materials, in particular to graphene-coated nano silicon and a preparation method thereof, and a silicon-carbon negative electrode material and a preparation method thereof.
Background
At present, a commercial lithium ion battery mainly adopts a graphite negative electrode material, but the theoretical specific capacity of the lithium ion battery is only 372mAh/g, and the requirement of the future lithium ion battery on high energy density cannot be met. Silicon has ultrahigh theoretical specific capacity (4200mAh/g) and lower lithium removal potential (<0.5V), and the voltage of silicon is slightly higher than that of graphite, so that surface lithium precipitation is not easy to cause during charging, and the safety performance is better, so that silicon becomes one of the potential choices of the carbon-based negative electrode material of the lithium ion battery.
However, silicon used as a negative electrode material of a lithium ion battery has disadvantages, such as that the silicon material is easy to expand in volume during charging and discharging, which leads to collapse of a conductive network and influences electrical cycle performance. At present, the volume expansion of silicon materials is improved mainly by the nanocrystallization and alloying of silicon and the compounding of silicon and active or inert materials; the composite material of carbon-coated silicon is concerned, but most of the small-particle-size nano silicon in the prior art is easy to agglomerate, so that the carbon coating is difficult and the carbon coating on the surface is not uniform.
Disclosure of Invention
An object of the embodiment of the application is to provide graphene-coated nano silicon and a preparation method thereof, a silicon-carbon negative electrode material and a preparation method thereof, and the purpose is to solve the problem that the surface carbon coating of the existing nano silicon-carbon-coated composite material is not uniform.
The first aspect of the application provides a method for coating nano silicon with graphene, which comprises the steps of preparing graphene coated nano silicon by adopting gas phase reaction equipment;
the gas phase reaction equipment is provided with a high temperature area positioned at the upstream of the carrier gas and a low temperature area positioned at the downstream of the carrier gas;
the method for coating nano silicon by graphene comprises the following steps:
the carrier gas carries silicon materials to react in a high-temperature area to prepare the nano silicon, and the carrier gas carries the nano silicon to a low-temperature area.
Introducing reaction gas into the low-temperature region, wherein the reaction gas forms a graphene layer on the surface of the nano silicon;
wherein the gas phase reaction equipment is any one equipment suitable for a gas condensation method, a hydrogen arc plasma method, a sputtering method, a vacuum deposition method, a mixed plasma method, a gas phase decomposition method, plasma heating physical vapor phase synthesis, a wire electric explosion technology, a laser-induction composite heating method or a laser-induced chemical vapor deposition method.
Generating nano silicon in a high-temperature area, carrying the nano silicon to a low-temperature area by carrier gas, introducing reaction gas in the low-temperature area, and carrying out in-situ reaction on the surface of the reaction gas by utilizing the high activity of the nano silicon to form graphene uniformly coated on the surface of the nano silicon, thereby obtaining the graphene coated nano silicon. In the process, the reaction gas is subjected to in-situ coating on the dynamic nano silicon surface, so that the possibility of nano silicon agglomeration can be reduced to avoid the growth of nano silicon and avoid the oversize silicon crystal grain; the graphene is uniformly loaded on the surface of the nano silicon, so that excessive nano silicon can be prevented from being exposed on the surface, and the problem of circulating water jump caused by consumption of electrolyte in the charging and discharging process is solved. The electrical property of the graphene coated nano silicon is effectively improved. The graphene-coated nano silicon obtained by the method can also effectively inhibit the volume expansion of the nano silicon.
In some embodiments of the first aspect of the present application, the gas phase reaction apparatus is selected from apparatus suitable for plasma heating physical gas phase synthesis, said silicon mass comprising metallurgical silicon.
In some embodiments of the first aspect of the present application, the silicon material is selected from any of metallurgical silicon or silane.
In some embodiments of the first aspect of the present application, the temperature of the low temperature region is 700-.
In some embodiments of the first aspect of the present application, the nanosilicon has a median particle size of 10 to 100 nm;
optionally, the morphology of the nano-silicon is spheroidal.
In some embodiments of the first aspect of the present application, the reactant gas is CH4And CO2OfAnd (5) gas synthesis.
The second aspect of the present application provides graphene-coated nano silicon, which is prepared by the method for coating graphene-coated nano silicon.
The third aspect of the present application provides a method for preparing a silicon-carbon negative electrode material, including: the silicon-carbon negative electrode material is prepared by mixing and granulating graphite, conductive carbon and the graphene-coated nano silicon;
optionally, the mass ratio of the graphite to the graphene-coated nano silicon is 2:1-1: 3;
optionally, the mass ratio of the nano silicon to the conductive carbon is 1:1-5: 1.
The fourth aspect of the application provides a silicon-carbon negative electrode material, and the silicon-carbon negative electrode material is prepared by the preparation method of the silicon-carbon negative electrode material provided by the third aspect.
The silicon-carbon negative electrode material powder provided by the embodiment of the application has the advantages of higher compacted density and better electrical property.
The fifth aspect of the present application provides a method for preparing a core-shell structure, wherein a gas phase reaction device is used for preparing the core-shell structure;
the gas phase reaction equipment is provided with a high temperature area positioned at the upstream of the carrier gas and a low temperature area positioned at the downstream of the carrier gas;
the preparation method of the core-shell structure comprises the following steps:
the inner core is prepared by carrying the inner core raw material with carrier gas to react in a high-temperature area, and the carrier gas carries the inner core to a low-temperature area.
Introducing a shell raw material into the low-temperature region, and performing vapor deposition on the shell raw material outside the inner core to form a shell layer;
wherein the gas phase reaction equipment is any one equipment suitable for a gas condensation method, a hydrogen arc plasma method, a sputtering method, a vacuum deposition method, a mixed plasma method, a gas phase decomposition method, plasma heating physical vapor phase synthesis, a wire electric explosion technology, a laser-induction composite heating method or a laser-induced chemical vapor deposition method.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
Fig. 1 shows a transmission electron microscope image of the graphene-coated nano silicon prepared in example 1.
Fig. 2 shows a particle size distribution diagram of the graphene-coated nano silicon prepared in example 1.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The graphene-coated nano silicon and the preparation method thereof, and the silicon-carbon negative electrode material and the preparation method thereof according to the embodiments of the present application are specifically described below.
A method for coating nano silicon with graphene adopts gas phase reaction equipment to prepare the nano silicon coated with graphene; the gas phase reaction apparatus has a high temperature region located upstream of the carrier gas and a low temperature region located downstream of the carrier gas.
The method for coating nano silicon by graphene comprises the following steps:
the carrier gas carries silicon materials to react in a high-temperature area to prepare the nano silicon, and the carrier gas carries the nano silicon to a low-temperature area. Introducing reaction gas into the low-temperature region, wherein the reaction gas forms a graphene layer on the surface of the nano silicon;
wherein the gas phase reaction equipment is any one equipment suitable for a gas condensation method, a hydrogen arc plasma method, a sputtering method, a vacuum deposition method, a mixed plasma method, a gas phase decomposition method, plasma heating physical vapor phase synthesis, a wire electric explosion technology, a laser-induction composite heating method or a laser-induced chemical vapor deposition method.
The method is suitable for any equipment of a gas condensation method, a hydrogen arc plasma method, a sputtering method, a vacuum deposition method, a mixed plasma method, a gas phase decomposition method, plasma heating physical vapor phase synthesis, a filament electric explosion technology, a laser-induction composite heating method or a laser-induced chemical vapor deposition method, wherein the equipment has a region with higher temperature and a region with lower temperature.
The temperature of the high-temperature area is higher than that of the low-temperature area, the carrier gas carries silicon materials to react in the high-temperature area to prepare nano silicon, and then graphene coating is carried out in the low-temperature area.
The carrier gas carries the nano-silicon to the low-temperature region, the nano-silicon generated in the high-temperature region has higher activity, and graphene generated by reaction of the reaction gas is coated on the surface of the high-activity nano-silicon in situ. In the process, reaction gas is subjected to in-situ coating on the dynamic nano silicon surface, so that the possibility of agglomeration of nano silicon can be reduced, and the oversize of silicon crystal grains is avoided; the graphene is uniformly loaded on the surface of the nano silicon, so that excessive nano silicon can be prevented from being exposed on the surface, and the problem of circulating water jump caused by consumption of electrolyte in the charging and discharging process is solved. The electrical property of the graphene coated nano silicon is effectively improved. In addition, the graphene-coated nano silicon obtained by the method can effectively inhibit the volume expansion of the nano silicon.
Illustratively, the silicon material is selected from metallurgical silicon or silane; in other embodiments of the present application, the silicon material may be at least one of polysilicon, monocrystalline silicon, or amorphous silicon.
Accordingly, any inert gas, such as argon, may be used as the carrier gas.
In the embodiment of the present application, the temperature of the high temperature region is 1200-1400 ℃, for example, the temperature of the high temperature region may be 1200 ℃, 1250 ℃, 1300 ℃, 1350 ℃, 1400 ℃, and so on.
Further, in the embodiment of the present application, the temperature of the low temperature region is 700-. In other words, the reaction gas generates graphene on the surface of the nano silicon in the region of 700-1100 ℃. The reaction gas is introduced into the region of 700 ℃ and 1100 ℃. For example, the temperature of the low temperature region may be 700 ℃, 950 ℃, 1000 ℃, 1020 ℃, 1050 ℃, 1100 ℃, or the like.
In some embodiments of the present application, the reactionGas is CH4And CO2The mixed gas of (1). CH (CH)4And CO2The mixed gas is reacted to generate graphene.
In some embodiments of the present application, the nano-silicon has a medium particle size of 10 to 100 nm; in other words, the speed of the carrier gas is controlled so that the medium particle diameter of the nano-silicon is 10 to 100 nm. Further, the shape of the nano silicon is similar to a sphere. In other embodiments of the present application, the particle size of the nano silicon may not be in the above range, and accordingly, the shape of the nano silicon may also be in other shapes.
Illustratively, the gas phase reaction equipment adopts an embodiment of gas phase synthesis equipment suitable for plasma heating physical gas phase synthesis, and the preparation method comprises the following steps:
putting silicon material into reactor, introducing protective gas such as helium or argon, heating the block silicon material by arc energy generated by plasma generator to melt and evaporate the block silicon material to form silicon vapor, condensing the reacted silicon molecular cluster into nano particles by condensing argon, helium or nitrogen, introducing CH at about 1000 deg.C in temperature zone of plasma reactor4And CO2And (3) carrying out graphene in-situ coating on the mixed gas, and finally, entering a grading device for carrying out particle size screening and grading to obtain the graphene in-situ coated nano silicon.
The gas phase reaction equipment adopts an embodiment suitable for hydrogen arc plasma method equipment, and the preparation method comprises the following steps:
putting silicon material into hydrogen arc plasma equipment powder preparing chamber, melting silicon by generating electric arc between plasma containing hydrogen and silicon, dissolving ionized argon, helium and hydrogen into molten silicon, then releasing, forming silicon ultramicron in gas, introducing CH at about 1000 deg.C in hydrogen arc plasma reactor temperature zone4And CO2Carrying out graphene in-situ coating on the mixed gas, and separating the nano silicon from the gas by using a centrifugal collector or a filtering collector to obtain graphene in-situ coated nano silicon;
the gas phase reaction equipment adopts an embodiment suitable for the equipment adopting the wire electric explosion method, and the preparation method comprises the following steps:
silicon is mixedThe filament is put into the filament electric explosion, the capacitor is used as an energy storage element, and after the capacitor is charged, the high-voltage trigger pulse is used for triggering the isolating switch to connect a discharging loop where the silicon filament is located. Under the high current pulse generated by the discharge of the capacitor, the silicon filament is melted and gasified by the self resistance heat to form silicon steam which expands in the cavity and collides with the surrounding gas to lose energy, the silicon steam is condensed to generate nano silicon powder, and CH is introduced into the filament electric explosion reactor at a temperature zone of about 1000 DEG C4And CO2And mixing the gases, and carrying out graphene in-situ coating to finally obtain the graphene in-situ coated nano silicon.
The gas phase reaction equipment adopts an embodiment suitable for laser induction composite heating method equipment, and the preparation method comprises the following steps:
putting a silicon material into a reaction crucible in laser induction composite heating equipment, vacuumizing, integrally heating the silicon material to a higher temperature by high-frequency induction, introducing laser to quickly evaporate the silicon material and generate a large temperature and pressure gradient, controlling the granularity of nano silicon by controlling the laser power, the temperature gradient and the pressure gradient, and introducing CH at a temperature zone of the laser induction composite heating equipment of about 1000 DEG C4And CO2And carrying out graphene in-situ coating on the mixed gas, and finally condensing and collecting to obtain the nano silicon.
The gas phase reaction equipment adopts an embodiment suitable for laser-induced chemical vapor deposition equipment, and the preparation method comprises the following steps:
introducing silane into a laser-induced chemical vapor deposition device, taking argon as protective gas, heating and dissociating silane gas molecules to generate supersaturated silicon vapor by utilizing the resonance absorption of silane gas to laser (10.6 mu m) with specific wavelength through laser photolysis, laser pyrolysis, laser photosensitization and laser-induced reaction, nucleating and growing into nano silicon particles in the transportation process, introducing CH at a temperature zone of about 1000 ℃ in a laser-induced vapor deposition reactor4And CO2And (3) mixing the gases, and carrying out graphene in-situ coating to finally obtain the graphene in-situ coated nano silicon particles.
By way of example, in embodiments of the present application, a carrier gas streamThe amount is 50-130m3The internal pressure of the reaction apparatus is from 60 to 130 kpa.
The method of the embodiment of the application is suitable for the gas phase reaction equipment.
The method provided by the embodiment of the application is not suitable for the following reaction equipment, for example:
(1) equipment which can not suspend nanometer powder, does not agglomerate the powder and is not carried away by carrier gas;
(2) the device does not have a low-temperature zone and cannot realize low-temperature zone coating or in-situ coating.
The method for coating nano silicon by graphene provided by the embodiment of the application has at least the following advantages:
and (3) carrying out in-situ coating on the nano-silicon by using corresponding gas phase reaction equipment, and coating the graphene before nano-silicon is agglomerated and crystal grains grow to obtain the graphene-coated nano-silicon particles with uniform coating and controllable particle size.
The embodiment of the application also provides graphene-coated nano silicon which is mainly prepared by the method, and the graphene-coated nano silicon is uniformly coated on the graphene layer at the outer layer, so that electrolyte is prevented from being consumed in the charging and discharging process due to the fact that excessive nano silicon is exposed on the surface, and the electrical property of the graphene-coated nano silicon is improved.
The application also provides a method for preparing a silicon-carbon negative electrode material by using the graphene coated nano silicon, which comprises the following steps:
the silicon-carbon negative electrode material is prepared by mixing and granulating graphite, conductive carbon and graphene-coated nano silicon.
As an example, graphite, conductive carbon, graphene-coated nano-silicon are uniformly dispersed in an alcohol solvent and then dried and granulated.
For example, the alcohol solvent may be at least one selected from the group consisting of methanol, ethanol, ethylene glycol, propanol, isopropanol, 1, 2-propanediol, glycerol, n-butanol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, n-pentanol, and 2-hexanol.
In some embodiments, the mass ratio of graphite to graphene-coated nano-silicon is 2:1 to 1: 3; for example, the mass ratio of graphite to graphene-coated nano-silicon may be 2:1, 1:1, 2:3, 2:5, or 1:3, etc.
In some embodiments, the mass ratio of nanosilicon to conductive carbon is from 1:1 to 5: 1; for example, it may be 1:1, 2:1, 3:1, 4:1, or 5:1, etc.
Accordingly, the drying granulation method may be spray drying, flash drying, freeze drying, or the like.
Further, in some embodiments of the present application, the preparation method of the silicon-carbon negative electrode material further includes coating the granulated product with amorphous carbon, and the carbon source of the amorphous carbon may be at least one selected from hydrocarbons, alkanes, alkenes, phenols, saccharides, organic acids, resins, and polymer materials. For example, it may be at least one selected from methane, ethylene, asphalt, phenol resin, epoxy resin, polyvinyl alcohol, polyvinyl chloride, polyethylene glycol, sucrose, glucose, and polyacrylonitrile.
Illustratively, in the granulating process, the coating proportion is 1-10%, the sintering temperature is 600-1000 ℃, and the thermal reduction time is 10-240 min. The temperature rise rate of the thermal reduction is 0.5-15.0 ℃/min.
It should be noted that in other embodiments of the present application, the silicon-carbon negative electrode material may also be prepared by using the graphene-coated nano silicon provided by the present application as a raw material and using other methods.
The embodiment of the application also provides a silicon-carbon negative electrode material which is prepared by the method.
The silicon-carbon negative electrode material provided by the embodiment of the application has the following advantages:
the silicon-carbon negative electrode material can compact powder through granulation of graphite and graphene coated nano silicon, the graphite acts as a framework, and the conductivity of the silicon-carbon negative electrode material can be improved.
The application also provides a preparation method of the core-shell structure, which adopts gas phase reaction equipment to prepare the core-shell structure;
the gas phase reaction apparatus has a high temperature region located upstream of the carrier gas and a low temperature region located downstream of the carrier gas.
The preparation method of the core-shell structure comprises the following steps:
and carrying the core raw material with carrier gas to react in the high-temperature area to prepare the core, and carrying the core with the carrier gas to the low-temperature area.
And introducing a shell raw material into the low-temperature area, and performing vapor deposition on the shell raw material outside the inner core to form a shell layer.
Wherein the gas phase reaction equipment is any one equipment suitable for a gas condensation method, a hydrogen arc plasma method, a sputtering method, a vacuum deposition method, a mixed plasma method, a gas phase decomposition method, plasma heating physical vapor phase synthesis, a wire electric explosion technology, a laser-induction composite heating method or a laser-induced chemical vapor deposition method.
The core-shell structure prepared by the method can realize in-situ coating of the core, and the core-shell structure with uniform particle size and uniform coating of the shell layer outside the core is obtained.
The features and properties of the present application are described in further detail below with reference to examples.
Example 1
The embodiment of the application provides a silicon-carbon negative electrode material which is mainly prepared by the following method:
preparing graphene-coated nano silicon:
adding the blocky silicon material into a crucible in a high-temperature evaporator through a charging hole, vacuumizing a reaction system, introducing argon as protective gas to ensure that the reaction system is inert and has the internal pressure of 100kpa, starting a plasma device, heating the blocky silicon material with the plasma heating power of 60KW by using the electric arc energy generated by a plasma generator to melt and evaporate the blocky silicon material to form silicon steam, and then introducing 40m of silicon steam3Condensing argon gas, condensing the reacted silicon molecular clusters into nano particles (with the median particle diameter of 50nm and spherical shape), and introducing CH at a temperature region of about 1000 ℃ in a plasma reactor4And CO2And hydrogen at a flow rate of 5m each3H and 10m3And h, carrying out graphene in-situ coating, and finally, entering a grading device for carrying out particle size screening and grading to obtain the graphene coated nano silicon, wherein the thickness of the graphene layer is 3 nm.
Mixing the graphene-coated nano silicon with ethanol, controlling the solid content to be 10%, uniformly stirring and dispersing, then adding graphite and glucose, wherein the mass ratio of the graphite to the graphene-coated nano silicon is 2:1, the mass ratio of the glucose to the graphene-coated nano silicon is 1:1, and granulating in a spray drying mode after uniform dispersion.
Mixing the granules obtained by granulation with asphalt, wherein the asphalt accounts for 10% of the total mass; and (3) protecting with nitrogen, heating at a speed of 3 ℃/min, carbonizing at 800 ℃, and naturally cooling after the heat preservation time is 3 hours to obtain the silicon-carbon negative electrode material.
Fig. 1 shows a transmission electron microscope image of the graphene-coated nano silicon prepared in example 1.
As can be seen from fig. 1, the graphene coating layer is successfully formed on the outer surface of the nano-silicon particle by using the present embodiment, and the graphene coating layer is dense and flat; the graphene is uniformly coated on the surface of the nano silicon.
Fig. 2 shows a particle size distribution diagram of the graphene-coated nano silicon prepared in example 1.
Fig. 2 shows that the graphene-coated nano-silicon particles prepared in example 1 have small particle sizes and concentrated particle size distribution, which indicates that nano-silicon does not significantly agglomerate when graphene is coated on nano-silicon.
Example 2
The embodiment of the application provides a silicon-carbon negative electrode material which is mainly prepared by the following method:
preparing graphene-coated nano silicon:
putting metallurgical silicon into a hydrogen arc plasma equipment powder preparation chamber, melting the silicon by generating an electric arc between plasma containing hydrogen and the silicon, dissolving ionized argon, helium and hydrogen into the molten silicon, then releasing the silicon to form silicon ultra-fine particles (with a middle particle diameter of 70nm and a spherical shape) in the gas, and introducing CH at a temperature of about 1000 ℃ in a hydrogen arc plasma reactor4And CO2And (3) carrying out graphene in-situ coating on the mixed gas, and separating the nano silicon from the gas by using a centrifugal collector or a filtering collector to obtain graphene in-situ coated nano silicon (hereinafter referred to as nano silicon/graphene particles), wherein the thickness of the graphene layer is 3 nm.
Mixing the graphene-coated nano silicon with ethanol, controlling the solid content to be 15%, uniformly stirring and dispersing, then adding graphite and sucrose, wherein the mass ratio of the graphite to the graphene-coated nano silicon is 2:1, the mass ratio of the sucrose to the graphene-coated nano silicon is 1:1, and granulating in a spray drying mode after uniform dispersion.
Mixing the granules obtained by granulation with asphalt, wherein the asphalt accounts for 10% of the total mass; and (3) protecting with nitrogen, heating at the speed of 5 ℃/min, carbonizing at the temperature of 900 ℃, and naturally cooling after the heat preservation time is 3 hours to obtain the silicon-carbon negative electrode material.
Example 3
The embodiment of the application provides a silicon-carbon negative electrode material which is mainly prepared by the following method:
preparing graphene-coated nano silicon:
the silicon wire is placed in wire electric explosion, the capacitor is used as an energy storage element, and after the capacitor is charged, the high-voltage trigger pulse is used for triggering the isolating switch to connect a discharging loop where the silicon wire is located. Under the large current pulse generated by the discharge of the capacitor, the silicon filament is melted and gasified by the self resistance heat to form silicon vapor which expands in the cavity and collides with the surrounding gas to lose energy, the silicon vapor is condensed to generate nano silicon powder (chain silicon with the length of 100 nm), and CH is introduced into the position of the temperature zone of the filament electric explosion reactor at about 1000 DEG C4And CO2And (3) carrying out graphene in-situ coating by using mixed gas to finally obtain graphene in-situ coated nano silicon (hereinafter referred to as chain silicon/graphene particles), wherein the thickness of the graphene layer is 3 nm.
Mixing the graphene-coated nano silicon with ethanol, controlling the solid content to be 15%, uniformly stirring and dispersing, then adding graphite and asphalt, wherein the mass ratio of the graphite to the graphene-coated nano silicon is 1:2, the mass ratio of the asphalt to the graphene-coated nano silicon is 1:1, and granulating in a spray drying mode after uniform dispersion.
Mixing the granules obtained by granulation with asphalt, wherein the asphalt accounts for 10% of the total mass; and (3) protecting with nitrogen, heating at the speed of 5 ℃/min, carbonizing at the temperature of 900 ℃, and naturally cooling after the heat preservation time is 3 hours to obtain the silicon-carbon negative electrode material.
Example 4
The embodiment of the application provides a silicon-carbon negative electrode material which is mainly prepared by the following method:
preparing graphene-coated nano silicon:
putting a silicon material into a reaction crucible in laser induction composite heating equipment, vacuumizing, integrally heating the silicon material to a higher temperature by high-frequency induction, introducing laser to quickly evaporate the silicon material and generate a great temperature and pressure gradient, controlling the granularity of nano silicon (spherical silicon with the particle size of 30 nm) by controlling the laser power, the temperature gradient and the pressure gradient, and introducing CH at a temperature zone of the laser induction composite heating equipment of about 1000 DEG C4And CO2And carrying out graphene in-situ coating on the mixed gas, and finally condensing and collecting to obtain nano silicon (hereinafter referred to as nano silicon/graphene particles), wherein the thickness of the graphene layer is 5 nm.
Mixing the graphene-coated nano silicon with methanol, controlling the solid content to be 5%, uniformly stirring and dispersing, and then adding graphite and phenolic resin, wherein the mass ratio of the graphite to the graphene-coated nano silicon is 1:2, the mass ratio of the phenolic resin to the graphene-coated nano silicon is 1:1, and the particles are uniformly dispersed and then granulated in a spray drying mode.
Mixing the granules obtained by granulation with asphalt, wherein the asphalt accounts for 10% of the total mass; and (3) protecting with nitrogen, heating at the speed of 5 ℃/min, carbonizing at the temperature of 900 ℃, and naturally cooling after the heat preservation time is 3 hours to obtain the silicon-carbon negative electrode material.
Example 5
The embodiment of the application provides a silicon-carbon negative electrode material which is mainly prepared by the following method:
preparing graphene-coated nano silicon:
introducing silane into a laser-induced chemical vapor deposition device, taking argon as protective gas, heating and dissociating silane gas molecules to generate supersaturated silicon vapor by utilizing the resonance absorption of silane gas to laser (10.6 mu m) with specific wavelength through laser photolysis, laser pyrolysis, laser photosensitization and laser-induced reaction, and nucleating and growing into nano silicon particles (20nm spherical silicon) in the transportation processIntroducing CH into the temperature zone of the laser-induced vapor deposition reactor at about 1000 DEG C4And CO2And (3) carrying out graphene in-situ coating by using mixed gas to finally obtain graphene in-situ coated nano silicon particles (hereinafter referred to as nano silicon/graphene particles), wherein the thickness of the graphene layer is 5 nm.
Mixing the graphene-coated nano silicon with propanol, controlling the solid content to be 5%, uniformly stirring and dispersing, then adding graphite and asphalt, wherein the mass ratio of the graphite to the graphene-coated nano silicon is 1:2, the mass ratio of the asphalt to the graphene-coated nano silicon is 1:1, and granulating in a spray drying mode after uniform dispersion.
Mixing the granules obtained by granulation with asphalt, wherein the asphalt accounts for 10% of the total mass; and (3) protecting with nitrogen, heating at the speed of 5 ℃/min, carbonizing at 950 ℃, preserving heat for 4 hours, and naturally cooling to obtain the silicon-carbon negative electrode material.
Comparative example 1
The comparative example provides a silicon carbon anode material, which is mainly prepared by the following method:
preparing sheet silicon slurry with the thickness of 100nm by a certain amount of sand milling method, enabling the solid content to be 10%, stirring and dispersing, placing graphite with the mass ratio to the nano silicon being 1:2 in the nano silicon solution, uniformly dispersing by a stirrer, placing phenolic resin with the mass ratio to the nano silicon being 1:1 in the solution, uniformly dispersing, granulating the composite solution in a spray drying mode, and synthesizing the graphene-coated nano silicon.
And mixing the graphene-coated nano silicon precursor with asphalt, wherein the asphalt accounts for 10% of the total mass of the graphene-coated nano silicon precursor and the asphalt, placing the mixture in a pushed slab kiln, carrying out solid phase coating, protecting with nitrogen, heating at the speed of 5 ℃/min and the carbonization temperature of 950 ℃, and naturally cooling after the heat preservation time of 4 hours to obtain the silicon-carbon cathode material.
Test examples
The silicon-carbon negative electrode materials provided by examples 1-5 and comparative example 1 are used for preparing batteries, and the specific steps for preparing the batteries comprise:
mixing and dissolving the silicon-carbon negative electrode material, the conductive agent and the binder in a solvent according to a mass ratio of 94:2:4, controlling the solid content to be 50%, and coating the mixture on a copper foil setDrying the fluid in vacuum to prepare a button cell which is assembled by a negative pole piece, electrolyte, an SK diaphragm, a lithium piece and a shell by adopting a conventional production process; wherein the solvent of the electrolyte is Ethylene Carbonate (EC), dimethyl carbonate (DMC) and ethylmethyl carbonate (EMC) in a volume ratio of 1:1: 1; the solute is LiPF6The concentration of the solute is 1 mol/L; and (3) testing the electrical property of the battery on the Shenzhen Xinwei Limited battery testing system. The test conditions were: at normal temperature, the constant current charge and discharge is carried out at 0.1C, and the charge and discharge cutoff voltage is 0.01V-1.5V. The test results are shown in Table 1.
TABLE 1 results of the Performance test of examples and comparative examples
Figure BDA0002593491720000151
As can be seen from table 1, the electrical properties of the silicon carbon anode materials prepared in examples 1 to 5 are better than those of comparative example 1, and the powder compaction density is also higher.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (10)

1. A method for coating nano silicon with graphene is characterized in that gas phase reaction equipment is adopted to prepare the graphene coated nano silicon;
the gas phase reaction equipment is provided with a high temperature area positioned at the upstream of the carrier gas and a low temperature area positioned at the downstream of the carrier gas;
the method for coating nano silicon by graphene comprises the following steps:
carrying silicon materials by carrier gas to react in the high-temperature area to prepare nano silicon; and
carrying the nano silicon to the low-temperature region by carrier gas, and introducing reaction gas capable of generating graphene into the low-temperature region to form a graphene layer on the surface of the nano silicon;
wherein the gas phase reaction equipment is any one equipment suitable for a gas condensation method, a hydrogen arc plasma method, a sputtering method, a vacuum deposition method, a mixed plasma method, a gas phase decomposition method, plasma heating physical vapor phase synthesis, a wire electric explosion technology, a laser-induction composite heating method or a laser-induced chemical vapor deposition method.
2. The method for coating nano-silicon by graphene according to claim 1, wherein the gas phase reaction equipment is selected from equipment suitable for plasma heating physical vapor phase synthesis, and the silicon material comprises metallurgical silicon.
3. The method for coating nano-silicon with graphene according to claim 1, wherein the silicon material is selected from any one of metallurgical silicon or silane.
4. The method as claimed in any one of claims 1 to 3, wherein the temperature of the low temperature region is 700-1100 ℃.
5. The method for coating nano silicon with graphene according to any one of claims 1 to 3, wherein the nano silicon has a medium particle size of 10 to 100 nm;
optionally, the morphology of the nano-silicon is spheroidal.
6. The method for coating nano silicon with graphene according to any one of claims 1 to 3, wherein the reaction gas is CH4And CO2The mixed gas of (1).
7. The graphene-coated nano silicon is prepared by the method of any one of claims 1 to 6.
8. A preparation method of a silicon-carbon negative electrode material is characterized by comprising the following steps: the silicon-carbon negative electrode material is prepared by mixing and granulating graphite, conductive carbon and the graphene-coated nano silicon of claim 7;
optionally, the mass ratio of the graphite to the graphene-coated nano silicon is 2:1-1: 3;
optionally, the mass ratio of the nano silicon to the conductive carbon is 1:1-5: 1.
9. A silicon-carbon anode material, which is prepared by the preparation method of the silicon-carbon anode material according to claim 8.
10. A preparation method of a core-shell structure is characterized in that a gas phase reaction device is adopted to prepare the core-shell structure;
the gas phase reaction equipment is provided with a high temperature area positioned at the upstream of the carrier gas and a low temperature area positioned at the downstream of the carrier gas;
the preparation method of the core-shell structure comprises the following steps:
carrying a core raw material with carrier gas to react in the high-temperature area to prepare a core, and carrying the core with the carrier gas to the low-temperature area;
introducing a shell raw material into the low-temperature zone, and performing vapor deposition on the shell raw material outside the inner core to form a shell layer;
wherein the gas phase reaction equipment is any one equipment suitable for a gas condensation method, a hydrogen arc plasma method, a sputtering method, a vacuum deposition method, a mixed plasma method, a gas phase decomposition method, plasma heating physical vapor phase synthesis, a wire electric explosion technology, a laser-induction composite heating method or a laser-induced chemical vapor deposition method.
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112520741A (en) * 2020-11-26 2021-03-19 宁波广新纳米材料有限公司 Production method of carbon-coated silicon powder for lithium battery negative electrode material
CN113410445A (en) * 2021-06-18 2021-09-17 电子科技大学 Silicon-carbon composite negative electrode material for secondary battery and preparation method thereof
CN115472809A (en) * 2022-10-26 2022-12-13 晖阳(贵州)新能源材料有限公司 Preparation method of graphite composite material with high first-time efficiency
CN115663153A (en) * 2022-11-11 2023-01-31 广东凯金新能源科技股份有限公司 Preparation method of metal-doped silicon-based negative electrode material, negative electrode material and secondary battery

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107611394A (en) * 2017-09-08 2018-01-19 成都硅宝科技股份有限公司 A kind of nuclear shell structure nano silicon/graphene composite negative pole of carbon coating and preparation method thereof
CN107709472A (en) * 2015-04-30 2018-02-16 卡博特公司 It is coated with the particle of carbon
CN109244378A (en) * 2017-07-10 2019-01-18 力信（江苏）能源科技有限责任公司 A kind of preparation method of porous nano Si-C composite material
CN109713285A (en) * 2018-12-29 2019-05-03 湖南中科星城石墨有限公司 A kind of silicon-carbon composite cathode material and preparation method thereof
CN110407198A (en) * 2019-08-14 2019-11-05 中国科学院重庆绿色智能技术研究院 The preparation and application of graphene nano silicon composite
CN110635128A (en) * 2019-09-26 2019-12-31 湖南中科星城石墨有限公司 Negative electrode composite material for lithium ion battery and preparation method thereof

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107709472A (en) * 2015-04-30 2018-02-16 卡博特公司 It is coated with the particle of carbon
CN109244378A (en) * 2017-07-10 2019-01-18 力信（江苏）能源科技有限责任公司 A kind of preparation method of porous nano Si-C composite material
CN107611394A (en) * 2017-09-08 2018-01-19 成都硅宝科技股份有限公司 A kind of nuclear shell structure nano silicon/graphene composite negative pole of carbon coating and preparation method thereof
CN109713285A (en) * 2018-12-29 2019-05-03 湖南中科星城石墨有限公司 A kind of silicon-carbon composite cathode material and preparation method thereof
CN110407198A (en) * 2019-08-14 2019-11-05 中国科学院重庆绿色智能技术研究院 The preparation and application of graphene nano silicon composite
CN110635128A (en) * 2019-09-26 2019-12-31 湖南中科星城石墨有限公司 Negative electrode composite material for lithium ion battery and preparation method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
吴骁: ""不同CO2流量对CVD金刚石膜生长的影响研究"", 《真空与低温》 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112520741A (en) * 2020-11-26 2021-03-19 宁波广新纳米材料有限公司 Production method of carbon-coated silicon powder for lithium battery negative electrode material
CN113410445A (en) * 2021-06-18 2021-09-17 电子科技大学 Silicon-carbon composite negative electrode material for secondary battery and preparation method thereof
CN115472809A (en) * 2022-10-26 2022-12-13 晖阳(贵州)新能源材料有限公司 Preparation method of graphite composite material with high first-time efficiency
CN115472809B (en) * 2022-10-26 2023-09-01 晖阳(贵州)新能源材料有限公司 Preparation method of graphite composite material with high first efficiency
CN115663153A (en) * 2022-11-11 2023-01-31 广东凯金新能源科技股份有限公司 Preparation method of metal-doped silicon-based negative electrode material, negative electrode material and secondary battery

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