CN112467102A - Preparation method of SiOx-Si @ C @ CNTs composite material - Google Patents

Preparation method of SiOx-Si @ C @ CNTs composite material Download PDF

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CN112467102A
CN112467102A CN202011271856.4A CN202011271856A CN112467102A CN 112467102 A CN112467102 A CN 112467102A CN 202011271856 A CN202011271856 A CN 202011271856A CN 112467102 A CN112467102 A CN 112467102A
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陈晨
梁栋栋
王健
毕超奇
蔡桂凡
林少雄
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Hefei Gotion High Tech Power Energy Co Ltd
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Hefei Guoxuan High Tech Power Energy 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
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    • H01M4/02—Electrodes composed of, or comprising, active material
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    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
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    • H—ELECTRICITY
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    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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Abstract

The invention discloses a SiOx-Si @ C @ CNTs composite material, wherein the composite material is of a core-shell structure, and the inner core is SiOxThe particle comprises a composite coating layer formed by uniformly dispersing nano-silicon in a carbon material, wherein the carbon material consists of thermally cracked carbon and carbon nanotubes; the SiOxThe mass ratio of the particles, the nano silicon, the thermal cracking carbon and the carbon nano tubes is (88-95): (5-12): (15-22): 3. SiO of the inventionxThe first coulombic efficiency of the-Si @ C @ CNTs composite material is obviously improved, and the cyclic stability is good.

Description

SiO (silicon dioxide)xPreparation method of (E) -Si @ C @ CNTs composite material
Technical Field
The invention relates to the technical field of lithium ion battery cathode materials, in particular to a lithium ion battery cathode materialSiO (silicon dioxide) powderx-Si @ C @ CNTs composite material.
Background
Lithium ion batteries are widely used in the fields of portable electronic devices, electric vehicles, aerospace and the like due to the advantages of high energy density, long cycle life, no memory effect and the like. However, the conventional graphite negative electrode material cannot meet the increasing demand of high-performance lithium ion batteries due to low theoretical capacity. The silicon material with the advantages of high theoretical capacity, low working potential, rich raw material sources and the like is considered to be one of the attractive cathode materials capable of replacing graphite. However, silicon expands seriously during charging and discharging, resulting in the fracture of SEI film on the surface of silicon particles, particle pulverization, collapse of electrode structure, loss of electric contact among silicon particles, active substances and current collectors, serious material capacity attenuation and poor cycle stability.
The theoretical capacity of the silicon oxide is far higher than that of graphite, and lithium oxide and lithium silicate formed in the primary lithium intercalation process are taken as inert phases to relieve the volume expansion of lithium-silicon alloying to a certain extent, and the cycling stability of the lithium-silicon alloying is superior to that of silicon, so that the lithium-silicon alloying is widely concerned by researchers. However, the intrinsic conductivity of silica is low, and the first coulombic efficiency is low. In order to improve the above defects and enhance the electrochemical performance of the silicon oxide, researchers have tried many methods, such as reducing the particle size, designing the porous structure, doping elements, and carbon coating the surface. Or the silicon oxide/carbon nanofiber composite material is prepared by adopting a high-energy ball milling method, the excellent cycle performance is shown, and the reversible capacity after 200 weeks of cycle is still 700 mAh/g. Or the porous silicon oxide/carbon composite material is prepared by a chemical vapor deposition method, compared with pure silicon oxide particles, the composite material shows reduced polarization, smaller electrode expansion and obviously improved cycle performance. The surface carbon coating and the addition of the nano carbon conductive material can enhance the conductivity of the silicon oxide, relieve the volume expansion in the charge-discharge process of the silicon oxide, improve the charge-discharge capacity of the silicon oxide to a certain extent and improve the cycle performance of the silicon oxide, but the initial coulombic efficiency and reversible capacity of the silicon oxide are still lower and need to be further improved.
Disclosure of Invention
Based on the technical problems in the prior art, the invention provides SiOx-Si @ C @ CNTs composite material.
The invention provides a SiOx-Si @ C @ CNTs composite material, wherein the composite material is of a core-shell structure, and the inner core is SiOxThe particle comprises a composite coating layer formed by uniformly dispersing nano-silicon in a carbon material, wherein the carbon material consists of thermally cracked carbon and carbon nanotubes; the SiOxThe mass ratio of the particles, the nano silicon, the thermal cracking carbon and the carbon nano tubes is (88-95): (5-12): (15-22): 3.
preferably, the SiOxThe average particle diameter of the particles is 5-8 μm; the thermal cracking carbon is prepared by high-temperature pyrolysis of a carbon source in an inert atmosphere, wherein the carbon source is at least one of styrene butadiene rubber, phenolic resin, glucose and polyacrylonitrile.
The invention also provides SiOxThe preparation method of the-Si @ C @ CNTs composite material comprises the following steps:
s1 SiO with average grain diameter of 5-8 μmxMixing the powder with a solvent, and performing ball milling treatment to obtain SiOxSizing agent;
s2, applying to the SiOxAdding nano silicon, styrene butadiene rubber and carbon nano tubes into the slurry, uniformly dispersing, and then carrying out spray drying to obtain precursor powder;
s3, pyrolyzing the precursor powder under the protection of inert atmosphere, and cooling to room temperature to obtain SiOx-Si @ C @ CNTs composites.
Wherein, SiOxThe powder may be purchased commercially or prepared by conventional methods, and may be, for example: placing SiO powder in an annealing furnace, heating to 1000-1200 ℃ under the protection of inert gas, carrying out heat preservation disproportionation for 2-5h, and then cooling to room temperature to obtain SiOxPowder, wherein the heating rate is 3-5 ℃/min, and the cooling rate is 1.5-3 ℃/min.
Preferably, in the step S1, SiOxThe mass ratio of the powder to the solvent is (3-4): (6-7); in the step S1, the ball-to-material ratio of the ball milling process is 20: (1-3) ball millingThe rotating speed is 1500-.
Preferably, the solvent is water.
Preferably, in the step S2, SiOxThe mass ratio of the nano silicon to the styrene butadiene rubber to the carbon nano tube is (88-95): (5-12): (15-25): 3.
preferably, in the step S2, the SiO layer is coated on the substratexAdding nano silicon into the slurry, uniformly dispersing by ultrasonic, adding styrene butadiene rubber and carbon nano tubes, uniformly dispersing by vacuum stirring, and then spray drying to obtain precursor powder.
Preferably, the frequency of the ultrasonic dispersion is 10-30kHz, and the dispersion time is 5-8 h.
Preferably, in the step S3, the D50 size of the precursor powder is 10-13 μm, and the tap density is 1.15-1.3cm3/g。
Preferably, in the step S3, the feeding speed of spray drying is 5-10kg/h, the inlet air temperature is 215-.
Preferably, in step S4, the pyrolysis specifically includes: heating to 800-950 ℃ at the heating rate of 3-5 ℃/min, and preserving the heat for 5-15 h; in the step S4, the cooling rate is 1-3 ℃/min.
Preferably, the inert gas is argon, nitrogen, or a combination thereof.
SiO (silicon dioxide)x-Si @ C @ CNTs composite material, which is prepared by the preparation method.
The invention has the following beneficial effects:
according to the invention, the carbon conductive material is doped in the silicon oxide material to enhance the conductivity of the silicon oxide, relieve the volume expansion in the charge-discharge process of the silicon oxide, improve the charge-discharge capacity of the silicon oxide to a certain extent and improve the cycle performance of the silicon oxide; the charge and discharge capacity and the first coulombic efficiency of the silicon monoxide are improved by doping the nano silicon material, so that the prepared SiOxThe first coulombic efficiency of the-Si @ C @ CNTs composite material is obviously improved, and the cyclic stability is good.
Drawings
FIGS. 1-2 show SiO prepared in example 2 of the present inventionxSEM image of-Si @ C @ CNTs composite.
FIG. 3 shows SiO obtained in example 2 of the present inventionxAnd the-Si @ C @ CNTs composite material is used as a negative electrode material and assembled into a charge-discharge curve of the lithium ion battery under different cycle times.
Detailed Description
The technical solution of the present invention will be described in detail below with reference to specific examples.
Example 1
Preparation of SiOx-Si @ C @ CNTs composite:
s1 SiO with an average particle size of 5 μmxThe mass ratio of the powder to the water is 4: 6 mixing, and performing ball milling treatment to obtain SiOxAnd (3) slurry, wherein the ball-milling ball-to-material ratio is 20: 2, the ball milling speed is 2000r/min, and the ball milling time is 6 h;
s2 SiOxAdding nano silicon into the slurry, performing ultrasonic dispersion for 5h under the condition of the frequency of 10kHz, adding styrene-butadiene rubber and carbon nano tubes, uniformly stirring and dispersing in vacuum, and then performing spray drying to obtain the D50 with the size of 12 mu m and the tap density of 1.15cm3A precursor powder of/g, wherein SiOxThe mass ratio of the nano silicon to the styrene butadiene rubber to the carbon nano tube is 95: 5: 18: the conditions for spray drying were as follows: the feeding speed is 5kg/h, the air inlet temperature is 215 ℃, the air outlet temperature is 110 ℃, the rotating speed of an atomizing disc is 13500r/min, and the negative pressure in the tower is 0.35 MPa;
s3, heating the precursor powder to 800 ℃ at a heating rate of 5 ℃/min under the protection of argon/nitrogen composite atmosphere, preserving heat for 6h, and cooling to room temperature at a cooling rate of 2 ℃/min to obtain SiOx-Si @ C @ CNTs composites.
Wherein, SiOxThe preparation method of the powder comprises the following steps: placing SiO powder in an annealing furnace, heating to 1050 ℃ at the heating rate of 4 ℃/min under the protection of argon gas, carrying out heat preservation disproportionation treatment for 3h, and then cooling to room temperature at the cooling rate of 2 ℃/min to obtain SiOxAnd (3) powder.
SiO obtained as described abovex-SThe i @ C @ CNTs composite material is of a core-shell structure, and the inner core is SiOxThe particles have a shell which is a composite coating layer formed by uniformly dispersing nano-silicon in a carbon material, wherein the carbon material consists of thermally cracked carbon and carbon nano-tubes, and SiOxThe mass ratio of the particles, the nano silicon, the thermal cracking carbon and the carbon nano tubes is 95: 5: 18:3, SiOxThe average particle size of the particles was 5 μm.
SiO prepared by the above methodx-Si @ C @ CNTs composite material is used as an active substance, and the active substance, SP, CMC and SBR are mixed according to the mass ratio of 80: 10: 5: 5, uniformly mixing, adding a proper amount of deionized water to prepare slurry, coating the obtained slurry on copper foil, punching into a circular pole piece with the diameter of 12mm, and then drying the pole piece in vacuum at 80 ℃ for 24 hours to remove water. In a glove box filled with argon, a metal lithium sheet is used as a counter electrode, a Celgard2500 polypropylene porous membrane is used as a diaphragm, and 1mol/L LiPF6/EC-EMC-DMC (volume ratio 1:1:1) solution is used as electrolyte to assemble the CR2032 button half cell.
The battery is subjected to constant current charge and discharge performance test on a battery test system (LAND CTR 2001A). And (3) testing conditions are as follows: the current density is 120mA/g (0.01C), and the voltage range is 0.01-1.5V. The test results were as follows: the first charge-discharge capacity is 1236.3mAh/g and 1759.2mAh/g, and the first coulombic efficiency is 70.3%.
The cycle test conditions were: the current density was 120mA/g in the first 10 weeks and 240mA/g from 11 weeks. After the material is cycled for 100 weeks under the conditions, the reversible capacity of the material is 1038.6mAh/g, and the capacity retention rate is 84.0%.
Example 2
Preparation of SiOx-Si @ C @ CNTs composite:
s1 SiO with an average particle size of 5 μmxThe mass ratio of the powder to the water is 4: 6 mixing, and performing ball milling treatment to obtain SiOxAnd (3) slurry, wherein the ball-milling ball-to-material ratio is 20: 1, ball milling rotation speed is 1800r/min, and ball milling time is 8 h;
s2 SiOxAdding nano silicon into the slurry, performing ultrasonic dispersion for 5 hours under the condition that the frequency is 15kHz, adding styrene-butadiene rubber and carbon nano tubes, uniformly stirring and dispersing in vacuum, and then performing spray drying to obtain D50The size is 12 μm and the tap density is 1.2cm3A precursor powder of/g, wherein SiOxThe mass ratio of the nano silicon to the styrene butadiene rubber to the carbon nano tube is 90: 10: 18: the conditions for spray drying were as follows: the feeding speed is 5kg/h, the air inlet temperature is 225 ℃, the air outlet temperature is 110 ℃, the rotating speed of an atomizing disc is 12500r/min, and the negative pressure in the tower is 0.3 MPa;
s3, heating the precursor powder to 850 ℃ at a heating rate of 5 ℃/min under the protection of argon/nitrogen composite atmosphere, preserving heat for 5h, and cooling to room temperature at a cooling rate of 2 ℃/min to obtain SiOx-Si @ C @ CNTs composites.
Wherein, SiOxThe preparation method of the powder comprises the following steps: placing SiO powder in an annealing furnace, heating to 1150 ℃ at a heating rate of 5 ℃/min under the protection of argon gas, carrying out heat preservation disproportionation for 3h, and then cooling to room temperature at a cooling rate of 2 ℃/min to obtain SiOxAnd (3) powder.
SiO obtained as described abovexthe-Si @ C @ CNTs composite material is of a core-shell structure, and the core is SiOxThe particles have a shell which is a composite coating layer formed by uniformly dispersing nano-silicon in a carbon material, wherein the carbon material consists of thermally cracked carbon and carbon nano-tubes, and SiOxThe mass ratio of the particles, the nano silicon, the thermal cracking carbon and the carbon nano tubes is 90: 10: 18:3, SiOxThe average particle size of the particles was 5 μm.
SiO prepared by the above methodx-Si @ C @ CNTs composite as active material, the cell was assembled according to the method of example 1, and a constant current charge and discharge performance test was performed on a cell test system (LAND CTR 2001A). And (3) testing conditions are as follows: the current density is 120mA/g (0.01C), and the voltage range is 0.01-1.5V. The test results were as follows: the first charge-discharge capacity is 1348.1mAh/g and 1874.4mAh/g, and the first coulombic efficiency is 71.9%.
The cycle test conditions were: the current density in the first 10 weeks is 100mA/g, the current density is increased to 200mA/g from 11 weeks, and after the circulation is carried out for 100 weeks, the reversible capacity of the material is 1116.2mAh/g, and the capacity retention rate is 82.8%.
FIG. 3 shows SiO obtained in example 2 of the present inventionx-Si @ C @ CNTs composite material is used as negative electrode material and assembled into lithiumAnd (3) a charge-discharge curve of the ion battery under different cycle times.
Example 3
Preparation of SiOx-Si @ C @ CNTs composite:
s1 SiO with an average particle size of 6 μmxThe mass ratio of the powder to the water is 3: 7, mixing, and performing ball milling treatment to obtain SiOxAnd (3) slurry, wherein the ball-milling ball-to-material ratio is 20: 1, ball milling rotation speed is 1500r/min, and ball milling time is 10 h;
s2, applying to the SiOxAdding nano silicon into the slurry, performing ultrasonic dispersion for 5h under the condition that the frequency is 15kHz, adding styrene-butadiene rubber and carbon nano tubes, uniformly stirring and dispersing in vacuum, and then performing spray drying to obtain the nano silicon-styrene-butadiene rubber-carbon nano tube composite material with the D50 size of 10.5 mu m and the tap density of 1.3cm3A precursor powder of/g, wherein SiOxThe mass ratio of the nano silicon to the styrene butadiene rubber to the carbon nano tube is 88: 12: 18: the conditions for spray drying were as follows: the feeding speed is 6kg/h, the air inlet temperature is 230 ℃, the air outlet temperature is 105 ℃, the rotating speed of an atomizing disc is 13500r/min, and the negative pressure in the tower is 0.2 MPa;
s3, heating the precursor powder to 880 ℃ at a heating rate of 3.5 ℃/min under the protection of argon/nitrogen composite atmosphere, preserving heat for 8h, and cooling to room temperature at a cooling rate of 2 ℃/min to obtain SiOx-Si @ C @ CNTs composites.
Wherein, SiOxThe preparation method of the powder comprises the following steps: placing SiO powder in an annealing furnace, heating to 1050 ℃ at the heating rate of 3 ℃/min under the protection of inert gas, carrying out heat preservation disproportionation for 5h, and then cooling to room temperature at the cooling rate of 1.5 ℃/min to obtain SiOxAnd (3) powder.
SiO obtained as described abovexthe-Si @ C @ CNTs composite material is of a core-shell structure, and the core is SiOxThe particles have a shell which is a composite coating layer formed by uniformly dispersing nano-silicon in a carbon material, wherein the carbon material consists of thermally cracked carbon and carbon nano-tubes, and SiOxThe mass ratio of the particles, the nano silicon, the thermal cracking carbon and the carbon nano tubes is 88: 12: 18:3, SiOxThe average particle size of the particles was 6 μm.
SiO prepared by the above methodx-Si @ C @ CNTs complexThe battery was assembled as in example 1, and a constant current charge/discharge performance test was performed on a battery test system (LAND CTR 2001A). And (3) testing conditions are as follows: the current density is 120mA/g (0.01C), and the voltage range is 0.01-1.5V. The test results were as follows: the first charge-discharge capacity is 1402.5mAh/g and 1926.5mAh/g, and the first coulombic efficiency is 72.8%.
The cycle test conditions were: the current density in the first 10 weeks is 120mA/g, the current density is increased to 240mA/g from 11 weeks, and after the circulation for 100 weeks, the reversible capacity of the material is 1154.25mAh/g, and the capacity retention rate is 82.3%.
Comparative example 1
Preparation of SiOx-C @ CNTs composite:
s1 SiO with an average particle size of 6 μmxThe mass ratio of the powder to the water is 3: 7, mixing, and performing ball milling treatment to obtain SiOxAnd (3) slurry, wherein the ball-milling ball-to-material ratio is 20: 1, ball milling rotation speed is 1500r/min, and ball milling time is 10 h;
s2, applying to the SiOxAdding styrene butadiene rubber and carbon nano tubes into the slurry, stirring and dispersing uniformly in vacuum, and then spray drying to obtain the D50 with the size of 10.5 mu m and the tap density of 1.3cm3A precursor powder of/g, wherein SiOxThe mass ratio of the styrene butadiene rubber to the carbon nano tube is 88:18:3, and the spray drying conditions are as follows: the feeding speed is 5kg/h, the air inlet temperature is 215 ℃, the air outlet temperature is 110 ℃, the rotating speed of an atomizing disc is 13500r/min, and the negative pressure in the tower is 0.35 MPa;
s3, heating the precursor powder to 880 ℃ at a heating rate of 3.5 ℃/min under the protection of argon/nitrogen composite atmosphere, preserving heat for 8h, and cooling to room temperature at a cooling rate of 2 ℃/min to obtain SiOx-Si @ C @ CNTs composites.
Wherein, SiOxThe preparation method of the powder comprises the following steps: placing SiO powder in an annealing furnace, heating to 1050 ℃ at the heating rate of 3 ℃/min under the protection of inert gas, carrying out heat preservation disproportionation for 5h, and then cooling to room temperature at the cooling rate of 1.5 ℃/min to obtain SiOxAnd (3) powder.
SiO prepared by the above methodx-C @ CNTs composites as compositesThe battery was assembled in the same manner as in example 1, and a constant current charge/discharge performance test was performed on the battery test system (LAND CTR 2001A). And (3) testing conditions are as follows: the current density is 120mA/g (0.01C), and the voltage range is 0.01-1.5V. The test results were as follows: the first charge-discharge capacity is 1107.6mAh/g and 1732.8mAh/g, and the first coulombic efficiency is 63.9%.
The cycle test conditions were: the current density in the first 10 weeks is 120mA/g, the current density is increased to 240mA/g from 11 weeks, and after the circulation for 100 weeks, the reversible capacity of the material is 944.78mAh/g, and the capacity retention rate is 85.3%.
Comparative example 2
Preparation of SiOx-Si @ C @ CNTs composite:
s1 SiO with an average particle size of 6 μmxThe mass ratio of the powder to the water is 3: 7, mixing, and performing ball milling treatment to obtain SiOxAnd (3) slurry, wherein the ball-milling ball-to-material ratio is 20: 1, ball milling rotation speed is 1500r/min, and ball milling time is 10 h;
s2, applying to the SiOxAdding nano silicon into the slurry, performing ultrasonic dispersion for 5h under the condition that the frequency is 15kHz, adding styrene-butadiene rubber and carbon nano tubes, uniformly stirring and dispersing in vacuum, and then performing spray drying to obtain the nano silicon-styrene-butadiene rubber-carbon nano tube composite material with the D50 size of 10.5 mu m and the tap density of 1.3cm3A precursor powder of/g, wherein SiOxThe mass ratio of the nano silicon to the styrene butadiene rubber to the carbon nano tube is 85: 15: 20: the conditions for spray drying were as follows: the feeding speed is 6kg/h, the air inlet temperature is 230 ℃, the air outlet temperature is 105 ℃, the rotating speed of an atomizing disc is 13500r/min, and the negative pressure in the tower is 0.2 MPa;
s3, heating the precursor powder to 880 ℃ at a heating rate of 3.5 ℃/min under the protection of argon/nitrogen composite atmosphere, preserving heat for 8h, and cooling to room temperature at a cooling rate of 2 ℃/min to obtain SiOx-Si @ C @ CNTs composites.
Wherein, SiOxThe preparation method of the powder comprises the following steps: placing SiO powder in an annealing furnace, heating to 1050 ℃ at the heating rate of 3 ℃/min under the protection of inert gas, carrying out heat preservation disproportionation for 5h, and then cooling to room temperature at the cooling rate of 1.5 ℃/min to obtain SiOxAnd (3) powder.
SiO obtained as described abovexthe-Si @ C @ CNTs composite material is of a core-shell structure, and the core is SiOxThe particles have a shell which is a composite coating layer formed by uniformly dispersing nano-silicon in a carbon material, wherein the carbon material consists of thermally cracked carbon and carbon nano-tubes, and SiOxThe mass ratio of the particles, the nano silicon, the thermal cracking carbon and the carbon nano tubes is 85: 15: 20: 3, SiOxThe average particle size of the particles was 6 μm.
SiO prepared by the above methodx-Si @ C @ CNTs composite as active material, the cell was assembled according to the method of example 1, and a constant current charge and discharge performance test was performed on a cell test system (LAND CTR 2001A). And (3) testing conditions are as follows: the current density is 120mA/g (0.01C), and the voltage range is 0.01-1.5V. The test results were as follows: the first charge-discharge capacity is 1430.2mAh/g and 1961.8mAh/g, and the first coulombic efficiency is 72.9%.
The cycle test conditions were: the current density in the first 10 weeks is 120mA/g, the current density is increased to 240mA/g from 11 weeks, and after the circulation for 100 weeks, the reversible capacity of the material is 1046.9mAh/g, and the capacity retention rate is 73.2%.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (10)

1. SiO (silicon dioxide)x-Si @ C @ CNTs composite material, characterized in that the composite material is of a core-shell structure, the core being SiOxThe particle comprises a composite coating layer formed by uniformly dispersing nano-silicon in a carbon material, wherein the carbon material consists of thermally cracked carbon and carbon nanotubes; the SiOxThe mass ratio of the particles, the nano silicon, the thermal cracking carbon and the carbon nano tubes is (88-95): (5-12): (15-22): 3.
2. SiO as claimed in claim 1x-Si @ C @ CNTs composite, characterized in that said SiOxOf granulesThe average grain diameter is 5-8 μm; the thermal cracking carbon is prepared by high-temperature pyrolysis of a carbon source in an inert atmosphere, wherein the carbon source is at least one of styrene butadiene rubber, phenolic resin, glucose and polyacrylonitrile.
3. SiO as claimed in claim 1 or 2xThe preparation method of the-Si @ C @ CNTs composite material is characterized by comprising the following steps of:
s1 SiO with average grain diameter of 5-8 μmxMixing the powder with a solvent, and performing ball milling treatment to obtain SiOxSizing agent;
s2, applying to the SiOxAdding nano silicon, a carbon source and carbon nanotubes into the slurry, uniformly dispersing, and then carrying out spray drying to obtain precursor powder;
s3, pyrolyzing the precursor powder under the protection of inert atmosphere, and cooling to room temperature to obtain SiOx-Si @ C @ CNTs composites.
4. SiO according to claim 3xThe preparation method of the-Si @ C @ CNTs composite material is characterized in that in the step S1, SiO is adoptedxThe mass ratio of the powder to the solvent is (3-4): (6-7); in the step S1, the ball-to-material ratio of the ball milling process is 20: (1-3), the ball milling rotating speed is 1500-.
5. SiO according to claim 3 or 4xThe preparation method of the-Si @ C @ CNTs composite material is characterized in that in the step S2, SiO is adoptedxThe mass ratio of the nano silicon to the carbon source to the carbon nano tube is (88-95): (5-12): (15-22): 3.
6. SiO according to any of claims 3 to 5x-Si @ C @ CNTs composite material, characterized in that, in step S2, SiO is addedxAdding nano silicon into the slurry, uniformly dispersing by ultrasonic, adding styrene butadiene rubber and carbon nano tubes, uniformly dispersing by vacuum stirring, and then spray drying to obtain precursor powder.
7. SiO as claimed in claim 6xThe preparation method of the-Si @ C @ CNTs composite material is characterized in that the ultrasonic dispersion frequency is 10-30kHz, and the dispersion time is 5-8 h.
8. SiO according to any of claims 3 to 7xThe preparation method of the-Si @ C @ CNTs composite material is characterized in that in the step S3, the D50 size of precursor powder is 10-13 mu m, and the tap density is 1.15-1.3cm3/g。
9. SiO according to any of claims 3 to 8xThe preparation method of the-Si @ C @ CNTs composite material is characterized in that in the step S3, the feeding speed of spray drying is 5-10kg/h, the air inlet temperature is 215-230 ℃, the air outlet temperature is 100-115 ℃, the rotating speed of an atomizing disc is 12000-13500r/min, and the negative pressure in the tower is 0.2-0.5 MPa.
10. SiO according to any of claims 3 to 9xThe preparation method of the-Si @ C @ CNTs composite material is characterized in that in the step S4, the specific steps of pyrolysis are as follows: heating to 800-950 ℃ at the heating rate of 3-5 ℃/min, and preserving the heat for 5-15 h; in the step S4, the cooling rate is 1-3 ℃/min.
CN202011271856.4A 2020-11-13 2020-11-13 Preparation method of SiOx-Si @ C @ CNTs composite material Pending CN112467102A (en)

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