CN117613184A - Sectional type silicon oxide carbon coating method - Google Patents
Sectional type silicon oxide carbon coating method Download PDFInfo
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- CN117613184A CN117613184A CN202311799620.1A CN202311799620A CN117613184A CN 117613184 A CN117613184 A CN 117613184A CN 202311799620 A CN202311799620 A CN 202311799620A CN 117613184 A CN117613184 A CN 117613184A
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- 238000000576 coating method Methods 0.000 title claims abstract description 197
- NCZAACDHEJVCBX-UHFFFAOYSA-N [Si]=O.[C] Chemical compound [Si]=O.[C] NCZAACDHEJVCBX-UHFFFAOYSA-N 0.000 title description 5
- 239000011248 coating agent Substances 0.000 claims abstract description 185
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 146
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 145
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 118
- 239000000463 material Substances 0.000 claims abstract description 71
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 47
- 238000000034 method Methods 0.000 claims abstract description 24
- 238000012216 screening Methods 0.000 claims abstract description 9
- 239000010405 anode material Substances 0.000 claims abstract description 7
- 238000005253 cladding Methods 0.000 claims description 86
- 239000000377 silicon dioxide Substances 0.000 claims description 36
- 238000007599 discharging Methods 0.000 claims description 22
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 claims description 13
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 claims description 13
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 8
- 239000004215 Carbon black (E152) Substances 0.000 claims description 4
- 229930195733 hydrocarbon Natural products 0.000 claims description 4
- 150000002430 hydrocarbons Chemical class 0.000 claims description 2
- 239000000758 substrate Substances 0.000 claims 5
- VSTOHTVURMFCGL-UHFFFAOYSA-N [C].O=[Si]=O Chemical compound [C].O=[Si]=O VSTOHTVURMFCGL-UHFFFAOYSA-N 0.000 abstract description 7
- 239000007789 gas Substances 0.000 description 54
- 238000005229 chemical vapour deposition Methods 0.000 description 25
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 22
- 239000000523 sample Substances 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 13
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 10
- 229910052757 nitrogen Inorganic materials 0.000 description 10
- 229910052710 silicon Inorganic materials 0.000 description 10
- 239000010703 silicon Substances 0.000 description 10
- 239000000843 powder Substances 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- 229910052744 lithium Inorganic materials 0.000 description 5
- 238000010298 pulverizing process Methods 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000000354 decomposition reaction Methods 0.000 description 3
- 230000003111 delayed effect Effects 0.000 description 3
- 238000009830 intercalation Methods 0.000 description 3
- 230000002687 intercalation Effects 0.000 description 3
- 230000000670 limiting effect Effects 0.000 description 3
- 230000002035 prolonged effect Effects 0.000 description 3
- 235000012239 silicon dioxide Nutrition 0.000 description 3
- -1 small molecule hydrocarbon Chemical class 0.000 description 3
- OCKGFTQIICXDQW-ZEQRLZLVSA-N 5-[(1r)-1-hydroxy-2-[4-[(2r)-2-hydroxy-2-(4-methyl-1-oxo-3h-2-benzofuran-5-yl)ethyl]piperazin-1-yl]ethyl]-4-methyl-3h-2-benzofuran-1-one Chemical compound C1=C2C(=O)OCC2=C(C)C([C@@H](O)CN2CCN(CC2)C[C@H](O)C2=CC=C3C(=O)OCC3=C2C)=C1 OCKGFTQIICXDQW-ZEQRLZLVSA-N 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000007306 turnover Effects 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 229910004283 SiO 4 Inorganic materials 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000006257 cathode slurry Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000011267 electrode slurry Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 239000011856 silicon-based particle Substances 0.000 description 1
- 239000002153 silicon-carbon composite material Substances 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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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
- H01M4/04—Processes of manufacture in general
- H01M4/0402—Methods of deposition of the material
- H01M4/0421—Methods of deposition of the material involving vapour deposition
- H01M4/0428—Chemical vapour deposition
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/26—Deposition of carbon only
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/4417—Methods specially adapted for coating powder
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/54—Apparatus specially adapted for continuous coating
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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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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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
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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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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- H01M2004/021—Physical characteristics, e.g. porosity, surface area
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- 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
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- 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
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- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Silicon Compounds (AREA)
Abstract
The invention provides a sectional type silicon dioxide carbon coating method, and belongs to the technical field of batteries. The sectional type silicon dioxide carbon coating method comprises the following steps: 1) Crushing the silicon oxide to a micron level to obtain micron-level silicon oxide; 2) Feeding the micron-sized silicon oxide obtained in the step 1) into a pre-coating furnace of a continuous CVD device, and introducing coated carbon source gas for pre-coating; 3) Feeding the pre-coated micron-sized silicon oxide obtained in the step 2) into a main coating furnace of a continuous CVD device, and introducing coated carbon source gas for main coating; 4) And (3) screening, scattering and demagnetizing the coated micron-sized silicon oxide obtained in the step (3) to obtain the silicon oxide anode material. The method provided by the invention is mainly used for carbon coating of the silicon oxide, can enable the materials to have enough movement path in the furnace, has long carbon coating time, and can obtain the silicon oxide material with more uniform carbon layer, and has better electrochemical performance.
Description
Technical Field
The invention belongs to the technical field of batteries, and particularly relates to a sectional type silicon dioxide carbon coating method.
Background
The theoretical specific capacity of the silicon-based anode material is up to 4200mAh/g, the working voltage is low (less than 0.5V), the reserves are rich, and the silicon-based anode material is a potential anode material. However, silicon (Si) undergoes an alloying/dealloying process during charge and discharge, which is accompanied by a great volume expansion (> 300%), with the consequence of a series of problems such as material breakage, active material falling off, and instability of Solid Electrolyte (SEI) film, which seriously affect battery performance and safety performance.
In contrast, silicon oxide (SiOx, 0<x is less than or equal to 2) the material can form inactive Li in the first lithium intercalation process 2 O and Li 4 SiO 4 The inert substances are used as buffer layers, so that the volume expansion in the lithium intercalation process is obviously smaller than that of a pure silicon anode, but the expansion rate can reach 200 percent, andsilicon oxideIs stored in a memoryAmong other drawbacks are low conductivity and low first-order efficiency. To remedy the above-mentioned drawbacks, common and commercially available methods are: the surface of the silicon oxide is coated with a layer of carbon, and the coated carbon material can greatly improve the overall conductivity of the material; in the process of lithium intercalation and deintercalation, the surface carbon layer has a certain limiting effect on the expansion of the silicon, and the whole cycle performance of the material can be improved.
For the silicon oxide carbon coating method capable of meeting the industrial scale, a continuous CVD (Chemical Vapor Deposition) vapor deposition rotary kiln is generally adopted in the industry, namely, the silicon oxide is continuously fed and discharged in the kiln, and at the temperature, the material is coated by carbon decomposed by carbon source gas in the kiln. Although large continuous CVD rotary kiln can be manufactured with industrial yield, the fatal disadvantage is that caking is generated in the carbon coating process, and the inside of the kiln is blocked. The kiln is blocked and then can be dredged and cleaned after being cooled, which produces an excessively short production period and severely restricts the productivity. Compared with an intermittent coating kiln, the material is always in a coating area in the intermittent kiln, so that coating uniformity is ensured, but the material cannot be detected in the middle of production, and only data detection can be finally performed, so that the adjustment of intermediate process parameters is not facilitated. The continuous furnace is limited by the furnace structure, the decomposition area of the carbon source gas is limited, the material is coated in the movement process, the coating time is short, more carbon source gas is needed under the condition of the same carbon content, the coating uniformity is relatively poor, and the material performance is slightly poor.
Disclosure of Invention
In order to improve the technical problems occurring during the conventional CVD coating of the silicon oxide, the invention provides a sectional silicon oxide carbon coating method which is oriented to the industrialized large-scale preparation of carbon coated silicon oxide, not only can improve the performance of materials, but also can provide a longer production period and can improve the yield of unit production period.
The invention provides a sectional type silicon dioxide carbon coating method, which comprises the following steps:
1) Crushing the silicon oxide to a micron level to obtain micron-level silicon oxide;
2) Feeding the micron-sized silicon oxide obtained in the step 1) into a pre-coating furnace of a continuous CVD device, and introducing coated carbon source gas for pre-coating;
3) Feeding the pre-coated micron-sized silicon oxide obtained in the step 2) into a main coating furnace of a continuous CVD device, and introducing coated carbon source gas for main coating;
4) And (3) screening, scattering and demagnetizing the coated micron-sized silicon oxide obtained in the step (3) to obtain the silicon oxide anode material.
Further, in step 1), the particle size Dv50 of the micron-sized silica is 5 to 10um.
Further, in step 2) and step 3), the carbon source gas is a small molecular hydrocarbon;
preferably, the carbon source gas is at least one of methane and acetylene.
Further, in the step 2), during the pre-coating, the flow rate of the carbon source gas is 65-90L/min;
in the step 3), the flow rate of the carbon source gas is 40-75L/min during the main coating;
in the step 2), the content of contributing coating carbon is 0.1% -1% during pre-coating;
in the step 3), the content of the contributing coating carbon is 2-6% during the main coating.
Further, in the step 2), the feeding speed in the pre-coating is 10-100 kg/h;
in the step 3), the feeding speed is 10-100 kg/h during the main coating;
in the step 2), the rotating speed in the pre-cladding furnace is 10-18 min/turn;
in the step 3), the rotating speed in the main cladding furnace is 20-25 min/turn.
Further, in the step 2), the temperature of cladding in the pre-cladding furnace is 700-900 ℃;
in the step 3), the temperature of cladding is 900-1000 ℃ in the main cladding furnace.
The invention also proposes a continuous CVD apparatus for segmented silica-carbon coating, comprising:
the device comprises a pre-cladding furnace and a main cladding furnace, wherein the pre-cladding furnace is arranged at the upper left part of the main cladding furnace;
a first spiral conveyor used for conveying materials discharged from the buffer bin into the pre-coating furnace is arranged in the furnace body of the pre-coating furnace, at least one first turning plate is arranged on the inner wall of the first furnace body, the first spiral conveyor passes through the furnace body of the pre-coating furnace and the first furnace body to convey the materials into the first furnace body, a first air pipe used for conveying carbon source gas is also arranged in the pre-coating furnace, and a discharging bin used for discharging the materials in the first furnace body out of the pre-coating furnace is arranged below the discharging end of the pre-coating furnace;
a second screw conveyor for conveying the materials discharged by the discharging bin into the main cladding furnace is arranged at the feeding end of the main cladding furnace; the furnace body of the main cladding furnace is internally provided with a second furnace chamber, the inner wall of the second furnace chamber is provided with at least one second turning plate, the second screw conveyor passes through the furnace body of the main cladding furnace and the second furnace chamber to convey materials into the second furnace chamber, the main cladding furnace is internally provided with a second air pipe for conveying carbon source gas, and the discharge end of the main cladding furnace is provided with a discharge hole for discharging the materials in the second furnace chamber out of the main cladding furnace.
Further, the first air pipe is connected with an air source outside the furnace body of the pre-cladding furnace;
the second air pipe is connected with an air source outside the main cladding furnace body.
Further, a first bearing is arranged between the furnace body of the pre-cladding furnace and the first furnace liner, and the first bearing is driven by a motor to work;
a second bearing is arranged between the furnace body of the main cladding furnace and the second furnace liner, and the second bearing is driven by a motor to work;
the joint of the first spiral conveyor and the furnace body of the pre-cladding furnace is connected through a flange;
the second screw conveyor is connected with the junction of the main cladding furnace body through a flange.
Further, a first flap valve for controlling the material to enter and exit is arranged at the outlet of the cache bin;
and a second flap valve for controlling the material to enter and exit is arranged at the outlet of the discharging bin.
The invention has the following advantages:
the sectional type silicon dioxide carbon coating method provided by the invention adopts sectional type carbon coating, and the pre-coating and the main coating are sequentially carried out. The material is pre-coated in a pre-coating furnace, so that a carbon layer is obtained on the surface of the silicon oxide, the fluidity of the material is increased by the carbon layer, the turning opportunity of the silicon oxide during main coating can be greatly increased, and the equal opportunity of obtaining the carbon content of the silicon oxide particles is given. Because the material is coated in advance before entering the main coating furnace, the gas amount of the carbon source gas introduced into the main coating furnace is relatively low in unit time, the gas flow of the carbon source gas is reduced, the wall-forming time is further delayed, and the integral operation period of the CVD equipment can be effectively prolonged. And the material has enough movement path in the furnace, the material also undergoes more turnover, and the carbon coating time is long enough, so that the carbon layer is more uniform, and the obtained electrochemical performance is better.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:
FIG. 1 is a schematic view showing a structure of a continuous CVD apparatus according to the present invention; wherein, the reference numerals illustrate:
the pre-cladding furnace 1, a buffer bin 11, a first flap valve 12, a first screw conveyor 13, a first bearing 14, a first material turning plate 15, a first air pipe 16, a first furnace liner 17, a first discharge pipe 18,
The main cladding furnace 2, the discharging bin 21, the second flap valve 22, the second screw conveyor 23, the second bearing 24, the second material turning plate 25, the second air pipe 26, the second furnace pipe 27, the second discharging pipe 28 and the discharging hole 29;
FIG. 2 is a Scanning Electron Microscope (SEM) image of materials obtained in examples and comparative examples according to the present invention, wherein FIG. 2 (a) is a carbon-coated silica obtained in comparative example 3; FIG. 2 (b) shows the carbon-coated silica obtained in example 1;
FIG. 3 is a photograph showing the completion of carbon inclusion in a continuous CVD apparatus according to the examples and comparative examples of the present invention, wherein FIG. 3 (a) is a photograph showing the inside of the apparatus after carbon inclusion in comparative example 3 is completed; FIG. 3 (b) is a photograph showing the inside of the apparatus after the carbon packing in the main coating furnace of example 1 was completed.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. Embodiments of the invention and features of the embodiments may be combined with each other without conflict. In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. The terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first", "a second", etc. may explicitly or implicitly include one or more such feature. The terms "mounted," "connected," "coupled," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. When an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art in a specific case.
The prior commercialized silicon oxide CVD carbon coating technology is that the material is directly coated with carbon in a single furnace. Because carbon source gas can be rapidly decomposed at high temperature, the decomposition area is limited, the actual effective coating time of materials is short, the coating flow is large, the coating carbon content value is inevitably reached, but the coating is uneven, and the electrochemical performance of the materials is poor due to uneven coating. Under the same condition, the time of blocking the kiln is also related to the flow of the carbon source gas.
The embodiment of the invention provides a method for coating silicon dioxide carbon in a sectional manner, which comprises the following steps:
1) Crushing the silicon oxide to a micron level to obtain micron-level silicon oxide;
2) Putting the micron-sized silicon oxide obtained in the step 1) into a pre-coating furnace of a continuous CVD device, and introducing coated carbon source gas for pre-coating;
3) Feeding the pre-coated micron-sized silicon oxide obtained in the step 2) into a main coating furnace of a continuous CVD device, and introducing coated carbon source gas for main coating;
4) And (3) screening, scattering and demagnetizing the coated micron-sized silicon oxide obtained in the step (3) to obtain the silicon oxide anode material.
According to the sectional type silicon dioxide carbon coating method provided by the embodiment of the invention, sectional type carbon coating is adopted, the material is pre-coated in the pre-coating furnace, so that a carbon layer is obtained on the surface of the silicon dioxide, the fluidity of the material is increased by the carbon layer, the turning opportunity of the silicon dioxide in the process of main coating can be greatly increased, and equal opportunity of obtaining the carbon content of the silicon dioxide particles is given. Because the material is coated in advance before entering the main coating furnace, the gas amount of the carbon source gas introduced into the main coating furnace is relatively low in unit time, the gas flow of the carbon source gas is reduced, the wall-forming time is further delayed, and the integral operation period of the CVD equipment can be effectively prolonged. It can be seen that the sectional coating has significant advantages, firstly, the material has enough movement path in the furnace, the material also undergoes more turnover, and the carbon coating time is long enough, so that the carbon layer is more uniform; secondly, through setting up the carbon source air current in the cladding stove in advance, suitably reduce the carbon source air current in the main cladding stove, can make under the same carbon content circumstances, the cladding obtains the more even silica material of carbon layer, and then promotes the electrochemical performance of material to can effectively reduce the carbon caking in the device, promote the operating duration of equipment.
In step 1) of the embodiment of the invention, the silicon oxide is crushed to the micron level to obtain micron-level silicon oxide, so that the subsequent coating is facilitated.
Preferably, in step 1), the silica is pulverized by using a jet mill. The jet mill works in such a way that high-pressure gas is accelerated to high-speed air flow through a jet pipe, and the air drives material particles to accelerate, so that the material is crashed by collision, friction and shearing.
In one embodiment of the present invention, in step 1), the particle size Dv50 of the micron-sized silica is 5 to 10um; preferably, the particle size Dv50 of the microscale silica is 7 to 8 μm.
Preferably, in step 1), the micron-sized silica has a narrow distribution Span value of less than 1.2 during comminution.
In step 2) of the embodiment of the invention, the micron-sized silicon oxide is firstly pre-coated by adopting the carbon source gas, so that a carbon layer is obtained on the surface of the silicon oxide, the fluidity of materials is increased by the carbon layer, the turning opportunity of the silicon oxide in the main coating process can be greatly increased, and the equal opportunity of obtaining the carbon content of the silicon oxide particles is given.
In one embodiment of the present invention, in step 2), the carbon source gas is a small molecule hydrocarbon. Preferably, the carbon source gas is at least one of methane and acetylene. More preferably, the coated carbon source gas is acetylene.
In the step 2), the flow rate of the carbon source gas is 65-90L/min.
In one embodiment of the present invention, in step 2), the temperature of the cladding is 700-900 ℃ in the pre-cladding furnace.
Specifically, the blanking frequency of the pre-cladding furnace is 10-60 Hz. In order to maintain the consistency of the feed rate per hour, the screw conveyor operating parameters were adjusted so that the feed rate was 10 to 100kg/h at the time of pre-coating to ensure that the time of the material passing through the high temperature zone was sufficient. Preferably, the speed of the feed is 30-60 kg/h during pre-coating.
In one embodiment of the invention, in the step 2), the rotating speed in the pre-coating furnace is 10-18 min/turn. Specifically, the rotating speed of the first furnace liner in the pre-cladding furnace is 10-18 min/turn.
Preferably, in step 2), the main coating furnace is fed in a clockwise spiral direction.
Preferably, in step 2), nitrogen is used as a protective gas in the pre-coating furnace. The flow rate of the nitrogen is 10-100L/min.
In one embodiment of the present invention, in step 2), the content of the contributing cladding carbon in the pre-cladding is 0.1% to 1% (mass fraction); preferably, the content of the contributing coating carbon in the pre-coating is 0.5-1% (mass fraction). It is to be noted that the carbon content herein refers to the mass fraction of the carbon mass of the pre-coating in the silica after the carbon coating, i.e., the ratio of the mass of carbon/(the mass of carbon+the silica).
In step 3) of the embodiment of the invention, the carbon source gas is adopted to carry out main coating on the pre-coated micron-sized silicon oxide, and as the materials are pre-coated before entering the main coating furnace, the gas amount unit time of the carbon source gas introduced into the main coating furnace is relatively low, the gas flow of the carbon source is reduced, the wall junction time can be delayed, and the integral operation period of the CVD equipment can be effectively improved.
In one embodiment of the present invention, in step 3), the carbon source gas is a small molecule hydrocarbon. Preferably, the carbon source gas is at least one of methane and acetylene. More preferably, the coated carbon source gas is acetylene.
In the step 3), the flow rate of the carbon source gas is 40-75L/min during the primary coating. In the prior art, when carbon coating is carried out by adopting a single furnace time, in order to ensure the coating effect, the flow rate of the carbon source gas is generally 70-100L/min, but due to the limited decomposition area of the carbon source gas, the coating time is short, the coating uniformity is relatively poor, and carbon caking is easy to form in the device.
In one embodiment of the invention, in the step 3), the feeding speed is 10-100 kg/h during the main cladding; preferably, the speed of the feed is 40-60 kg/h in the primary coating.
In one embodiment of the present invention, in step 3), the rotational speed in the main coating furnace is 20 to 25 min/turn. Specifically, the rotating speed of the second furnace liner is 20-25 min/turn in the main cladding furnace. By controlling the feeding speed, the time of the material in the coating furnace can be effectively controlled, and the adjustment of the rotating speed is matched, so that the uniform coating of the carbon layer of the pre-coated silica in the main coating furnace is realized.
Preferably, the main cladding furnace is fed in a clockwise spiral direction.
In the step 3), the temperature of cladding in the main cladding furnace is 900-1000 ℃; preferably, the temperature of the cladding is 850-1050 ℃ in the main cladding furnace.
In the step 3), the carbon content of the contribution coating is 2-6% (mass fraction) in the main coating; preferably, the content of the contributing coating carbon in the primary coating is 2-5% (mass fraction). It is to be noted that the carbon content herein refers to the mass fraction of the carbon mass of the primary coating in the silica after the carbon coating, i.e., the ratio of the mass of carbon/(the mass of carbon+the silica). In the embodiment of the invention, the contribution amount of the coated carbon is mainly the contribution of the main coating, so that the operation period of the device can be effectively prolonged as long as the main coating is ensured not to be easy to generate carbon agglomeration, and the carbon agglomeration in the main coating furnace can be effectively avoided by reducing the flow of the carbon source gas during the main coating.
As shown in fig. 1, an embodiment of the present invention further provides a continuous CVD apparatus for sectional silicon carbide coating, including:
the device comprises a pre-cladding furnace 1 and a main cladding furnace 2, wherein the pre-cladding furnace 1 is arranged at the upper left part of the main cladding furnace 2;
the feeding end of the pre-coating furnace 1 is provided with a buffer bin 11 for buffering materials, a first spiral conveyor 13 for conveying the materials discharged from the buffer bin 11 into the pre-coating furnace 1, a first furnace liner 17 is arranged in the furnace body of the pre-coating furnace, at least one first turning plate 15 is arranged on the inner wall of the first furnace liner 17, the first spiral conveyor 13 passes through the furnace body of the pre-coating furnace 1 and the first furnace liner 17 to convey the materials into the first furnace liner 17, a first air pipe 16 for conveying carbon source gas is also arranged in the pre-coating furnace 1, and a discharging bin 21 for discharging the materials in the first furnace liner 17 out of the pre-coating furnace 1 is arranged below the discharging end of the pre-coating furnace 1;
a second screw conveyor 23 for feeding the materials discharged from the discharging bin 21 into the main cladding furnace 2 is arranged at the feeding end of the main cladding furnace 2; the furnace body of the main cladding furnace 2 is internally provided with a second furnace chamber 27, the inner wall of the second furnace chamber 27 is provided with at least one second turning plate 25, the second screw conveyor 23 penetrates through the furnace body of the main cladding furnace 2 and the second furnace chamber 27 to convey materials into the second furnace chamber 27, the main cladding furnace 2 is internally provided with a second air pipe 26 for conveying carbon source gas, and the discharge end of the main cladding furnace 2 is provided with a discharge hole 29 for discharging the materials in the second furnace chamber 27 out of the main cladding furnace 2.
In the embodiment of the invention, the continuous CVD device for sectional type silicon oxide carbon coating comprises a pre-coating furnace and a main coating furnace, wherein the pre-coating is realized in the pre-coating furnace, and then the main coating is realized in the main coating furnace, so that the uniform coating of carbon is realized.
In the embodiment of the invention, before the micron-sized silicon oxide is put into the pre-cladding furnace of the continuous CVD device, a buffer bin is needed, and the blanking speed is controlled by utilizing a first flap valve through frequency adjustment. To maintain hourly feed rate uniformity, screw conveyor operating parameters are adjusted to control feed rate to ensure that the time that the material passes through the high temperature zone is sufficient.
In the embodiment of the invention, a first flap valve 12 for controlling the material to enter and exit is arranged at the outlet of the buffer bin 11 in the pre-cladding furnace 1.
A first bearing 14 is arranged between the furnace body of the pre-cladding furnace 1 and a first furnace liner 17, and the first bearing 14 is driven by a motor to work.
The first screw conveyor 13 is connected with the junction of the furnace body of the pre-cladding furnace 1 through a flange.
A first discharge pipe 18 is arranged between the first flap valve 12 and the first screw conveyor 13.
An opening and closing door is arranged at the discharge end of the pre-cladding furnace 1.
The lower part of the buffer bin 11 is in an inverted cone shape.
In the embodiment of the invention, a second flap valve 22 for controlling the material to enter and exit is arranged at the outlet of the discharging bin 21 in the main cladding furnace 2.
A second bearing 24 is arranged between the furnace body of the main cladding furnace 2 and a second furnace liner 27, and the second bearing 24 is driven by a motor to work.
The second screw conveyor 23 is connected with the junction of the main cladding furnace 2 through a flange.
A second discharge pipe 28 is arranged between the second flap valve 22 and the second screw conveyor 23.
The first screw conveyor 13 and the second screw conveyor 23 are driven to work by motors.
The lower part of the discharging bin 21 is in an inverted cone shape.
The present invention will be described in detail below with reference to the accompanying drawings.
The following examples and comparative examples employ the continuous CVD apparatus for staged silica carbon coating proposed by the present invention for staged silica carbon coating.
Example 1A method of segmented silica carbon coating comprising:
pulverizing raw material silica powder to Dv50=7-8 μm, with Span value of 1.1; feeding the crushed silicon into a continuous CVD device, wherein the feeding speed of a pre-coating furnace is 50Kg/h, the feeding speed of nitrogen is 33.5L/min, the feeding speed of acetylene gas is 77.2L/min, the coating area temperature of the pre-coating furnace is 850 ℃, and the carbon content contributed by the pre-coating furnace is 0.8%. The silica material is subjected to main coating in a main coating furnace, wherein the coating temperature of the furnace is 985 ℃, the nitrogen is introduced into the furnace at 26.5L/min, the acetylene gas at 45.6L/min, and the content of the contributing coating carbon during the main coating is 2.8%. After coating, the sample is subjected to scattering, screening and demagnetizing, wherein the carbon content of the sample is 3.6%, and Dv50=8.5-9.5 μm.
The Scanning Electron Microscope (SEM) of the obtained carbon-coated silica is shown in fig. 2 (b). Fig. 3 (b) is a photograph of the inside of the apparatus after the carbon inclusion is completed.
Example 2A method of segmented silica carbon coating comprising:
pulverizing raw material silica powder to Dv50=7-8 μm, with Span value of 1.1; feeding the crushed silicon into a continuous CVD device, wherein the feeding speed of a pre-coating furnace is 55Kg/h, the feeding speed of nitrogen is 33.5L/min, the feeding speed of acetylene gas is 90.5L/min, the coating area temperature of the pre-coating furnace is 900 ℃, and the carbon content contributed by the pre-coating furnace is 0.7%. The silica material is subjected to main coating in a main coating furnace, the coating temperature of the furnace is 950 ℃, the nitrogen is introduced into the furnace at 34.5L/min, the acetylene gas is at 52.8L/min, and the content of the contribution coating carbon is 3.2% during the main coating. After coating, the sample is subjected to scattering, screening and demagnetizing, wherein the carbon content of the sample is 3.9%, and Dv50=9-10 μm.
Comparative example 1A method of silica carbon coating comprising:
pulverizing raw material silica powder to Dv50=7-8 μm, with Span value of 1.1; feeding the crushed silicon into a continuous CVD device, wherein the feeding speed of a pre-coating furnace is 50Kg/h, the nitrogen is introduced at 33.5L/min, no carbon source gas is introduced, the temperature of a coating area of the pre-coating furnace is not set, and the pre-coating furnace does not contribute carbon content. The silica material was carbon coated in a main coating furnace at a coating temperature of 985 c with nitrogen gas at 42.3L/min and acetylene gas at 66.5L/min, at which time the contributing coating carbon content was 3.7%. After coating, the sample is subjected to scattering, screening and demagnetizing, wherein the carbon content of the sample is 3.7%, and Dv50=8.5-10 μm.
Comparative example 2A method of silica carbon coating comprising:
pulverizing raw material silica powder to Dv50=7-8 μm, with Span value of 1.1; feeding the crushed silicon into a continuous CVD device, wherein the feeding speed of a pre-coating furnace is 55Kg/h, the feeding speed of nitrogen is 33.5L/min, the feeding speed of methane gas is 210.5L/min, the coating area temperature of the pre-coating furnace is 900 ℃, and the contribution of the pre-coating furnace to the coating carbon content is 3.8%. The temperature of the cladding area of the main cladding furnace is not set, the nitrogen is introduced at 34.5L/min, no carbon source gas is introduced, and the main cladding furnace has no contribution of carbon content. After coating, the sample is subjected to scattering, screening and demagnetizing, wherein the carbon content of the sample is 3.8%, and Dv50=9.5-10.5 μm.
Comparative example 3A method (conventional method) of carbon-coating silicon oxide, comprising:
the difference was that the acetylene gas flow rate was adjusted from 66.5L/min to 85L/min, as in comparative example 1.
The method comprises the following steps:
pulverizing raw material silica powder to Dv50=7-8 μm, with Span value of 1.1; feeding the crushed silicon into a continuous CVD device, wherein the feeding speed of a pre-coating furnace is 50Kg/h, the nitrogen is introduced at 33.5L/min, no carbon source gas is introduced, the temperature of a coating area of the pre-coating furnace is not set, and the pre-coating furnace does not contribute carbon content. The silica material was carbon coated in a main coating furnace at a coating temperature of 985 c with nitrogen gas at 42.3L/min and acetylene gas at 85L/min, at which time the contributing coating carbon content was 3.90%. After coating, the sample is subjected to scattering, screening and demagnetizing, wherein the carbon content of the sample is 3.90%, and Dv50=9-10 μm.
Fig. 2 (a) is a Scanning Electron Microscope (SEM) image of the resulting carbon-coated silica. Fig. 3 (a) is a photograph of the inside of the device after carbon inclusion is completed.
Test example 1The effects produced by the methods set forth in the examples and comparative examples were tested
1) Resistivity detection method
A semiconductor powder resistivity analyzer (ST 2722 type powder four-probe resistivity tester, 30MPa four-probe) was used;
calibration is carried out by using a calibration block before testing; zeroing the charging cavity on a weighing balance, and weighing 0.3-0.32g of carbon-coated products obtained in the examples and the comparative examples respectively; the method comprises the steps of performing sample testing, rotating a hand wheel anticlockwise, pressing down an upper electrode, starting to press a sample when the upper electrode is pressed to a table top, and manually collecting data every 2Mpa when the sample is tested, until the pressure is 20Mpa, and stopping measurement; and finally, carrying out data processing. The results are shown in Table 1.
2) Capacity and first-effect testing
The products obtained in the examples and the comparative examples are respectively used as negative electrode materials to prepare a button cell with a molding number 2032, and the specific steps are as follows: mixing a silicon-carbon composite material, a conductive agent SP, a dispersing agent CMC and a binder AONE according to the mass ratio of 70:15:5:10, and preparing negative electrode slurry by taking water as a solvent; coating the cathode slurry on a copper foil, and preparing a button cell by taking a lithium sheet as a counter electrode and taking a Celgard 2400 microporous polypropylene film as a diaphragm;
the obtained button cell is subjected to charge-discharge circulation, and the charge-discharge conditions are as follows: the charge-discharge cut-off voltage is 0.005-1.5V, the discharge multiplying power is that 0.1C is firstly put to 0.005V, then 0.02C is put to 0.005V, the discharge is sufficient, the charge multiplying power is that 0.1C is charged to 1.5V, and the reversible capacity and the first coulomb efficiency of the button cell are detected. The results are shown in Table 1.
TABLE 1
From Table 1, it is understood that the present invention can increase the operation time of the CVD apparatus by at least one time or more from the operation cycle. The silicon oxide itself is not conductive and is conductive after being coated with a carbon layer, so the conductivity of the material is used here to characterize the coating uniformity (the smaller the value of the resistivity, the better the conductivity). As can be seen from fig. 2, the material surface of fig. 2 (a) is rough, the material surface of fig. 2 (b) is smooth, and the material surface coated twice is smooth, because the coating of the carbon layer is uniform. As can be seen from table 1 and fig. 2: under the condition of equivalent carbon content, the material prepared by the invention has better conductive performance and better coating effect; due to good coating uniformity, li can be ensured during button performance test + Is embedded into each silicon particle as much as possible, so the capacity and the first effect are improved. As can be seen from fig. 3, fig. 3 (a) shows the state of the furnace caking after the primary coating in comparative example 3, and the furnace caking is more; FIG. 3 (b) shows the state of caking in the main coating furnace after the secondary coating in example 1, the number of caking in the furnace is small, and the caking phenomenon after the modification can be clearly seen to be obviously improved after the carbon coating of the kiln is completed.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (10)
1. A method of sectional silica carbon coating comprising the steps of:
1) Crushing the silicon oxide to a micron level to obtain micron-level silicon oxide;
2) Feeding the micron-sized silicon oxide obtained in the step 1) into a pre-coating furnace of a continuous CVD device, and introducing coated carbon source gas for pre-coating;
3) Feeding the pre-coated micron-sized silicon oxide obtained in the step 2) into a main coating furnace of a continuous CVD device, and introducing coated carbon source gas for main coating;
4) And (3) screening, scattering and demagnetizing the coated micron-sized silicon oxide obtained in the step (3) to obtain the silicon oxide anode material.
2. The method of claim 1, wherein the step of determining the position of the substrate comprises,
in step 1), the particle size Dv50 of the micron-sized silica is 5 to 10um.
3. The method of claim 1, wherein the step of determining the position of the substrate comprises,
in the step 2) and the step 3), the coated carbon source gas is micromolecular hydrocarbon;
preferably, the carbon source gas is at least one of methane and acetylene.
4. The method of claim 1, wherein the step of determining the position of the substrate comprises,
in the step 2), during the pre-coating, the flow rate of the carbon source gas is 65-90L/min;
in the step 3), the flow rate of the carbon source gas is 40-75L/min during the main coating;
in the step 2), the content of contributing coating carbon is 0.1% -1% during pre-coating;
in the step 3), the content of the contributing coating carbon is 2-6% during the main coating.
5. The method of claim 1, wherein the step of determining the position of the substrate comprises,
in the step 2), the feeding speed in the pre-coating is 10-100 kg/h;
in the step 3), the feeding speed is 10-100 kg/h during the main coating;
in the step 2), the rotating speed in the pre-cladding furnace is 10-18 min/turn;
in the step 3), the rotating speed in the main cladding furnace is 20-25 min/turn.
6. The method of claim 1, wherein the step of determining the position of the substrate comprises,
in the step 2), the temperature of cladding is 700-900 ℃ in a pre-cladding furnace;
in the step 3), the temperature of cladding is 900-1000 ℃ in the main cladding furnace.
7. A continuous CVD apparatus for segmented silica carbon coating, comprising:
the device comprises a pre-cladding furnace and a main cladding furnace, wherein the pre-cladding furnace is arranged at the upper left part of the main cladding furnace;
a first spiral conveyor used for conveying materials discharged from the buffer bin into the pre-coating furnace is arranged in the furnace body of the pre-coating furnace, at least one first turning plate is arranged on the inner wall of the first furnace body, the first spiral conveyor passes through the furnace body of the pre-coating furnace and the first furnace body to convey the materials into the first furnace body, a first air pipe used for conveying carbon source gas is also arranged in the pre-coating furnace, and a discharging bin used for discharging the materials in the first furnace body out of the pre-coating furnace is arranged below the discharging end of the pre-coating furnace;
a second screw conveyor for conveying the materials discharged by the discharging bin into the main cladding furnace is arranged at the feeding end of the main cladding furnace; the furnace body of the main cladding furnace is internally provided with a second furnace chamber, the inner wall of the second furnace chamber is provided with at least one second turning plate, the second screw conveyor passes through the furnace body of the main cladding furnace and the second furnace chamber to convey materials into the second furnace chamber, the main cladding furnace is internally provided with a second air pipe for conveying carbon source gas, and the discharge end of the main cladding furnace is provided with a discharge hole for discharging the materials in the second furnace chamber out of the main cladding furnace.
8. The continuous CVD apparatus according to claim 7, wherein,
the first air pipe is connected with an air source outside the furnace body of the pre-cladding furnace;
the second air pipe is connected with an air source outside the main cladding furnace body.
9. The continuous CVD apparatus according to claim 7, wherein,
a first bearing is arranged between the furnace body of the pre-cladding furnace and the first furnace liner, and the first bearing is driven by a motor to work;
a second bearing is arranged between the furnace body of the main cladding furnace and the second furnace liner, and the second bearing is driven by a motor to work;
the joint of the first spiral conveyor and the furnace body of the pre-cladding furnace is connected through a flange;
the second screw conveyor is connected with the junction of the main cladding furnace body through a flange.
10. The continuous CVD apparatus according to claim 7, wherein,
a first flap valve for controlling the material to enter and exit is arranged at the outlet of the cache bin;
and a second flap valve for controlling the material to enter and exit is arranged at the outlet of the discharging bin.
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