CN116730345A - Silicon nanowire and preparation method and application thereof - Google Patents
Silicon nanowire and preparation method and application thereof Download PDFInfo
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 145
- 239000010703 silicon Substances 0.000 title claims abstract description 135
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 135
- 239000002070 nanowire Substances 0.000 title claims abstract description 79
- 238000002360 preparation method Methods 0.000 title claims abstract description 34
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 73
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 69
- 238000001704 evaporation Methods 0.000 claims abstract description 36
- 230000008020 evaporation Effects 0.000 claims abstract description 31
- 238000000034 method Methods 0.000 claims abstract description 31
- 238000004519 manufacturing process Methods 0.000 claims abstract description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 42
- 239000000377 silicon dioxide Substances 0.000 claims description 16
- 235000012239 silicon dioxide Nutrition 0.000 claims description 16
- 238000010438 heat treatment Methods 0.000 claims description 13
- 239000011863 silicon-based powder Substances 0.000 claims description 11
- 239000012300 argon atmosphere Substances 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 9
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 9
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 7
- 239000010931 gold Substances 0.000 claims description 7
- 229910052737 gold Inorganic materials 0.000 claims description 7
- 238000007747 plating Methods 0.000 claims description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 6
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 6
- 229910052744 lithium Inorganic materials 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 229910052709 silver Inorganic materials 0.000 claims description 6
- 239000004332 silver Substances 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 5
- 230000035484 reaction time Effects 0.000 claims description 2
- 239000004411 aluminium Substances 0.000 claims 4
- 239000003795 chemical substances by application Substances 0.000 abstract description 4
- 238000002844 melting Methods 0.000 abstract description 4
- 230000008018 melting Effects 0.000 abstract description 4
- 230000000052 comparative effect Effects 0.000 description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 9
- 239000002086 nanomaterial Substances 0.000 description 7
- 238000005229 chemical vapour deposition Methods 0.000 description 6
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 239000000758 substrate Substances 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 4
- 239000002041 carbon nanotube Substances 0.000 description 4
- 229910021393 carbon nanotube Inorganic materials 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000001000 micrograph Methods 0.000 description 4
- 229910052573 porcelain Inorganic materials 0.000 description 4
- 238000000151 deposition Methods 0.000 description 3
- 238000000608 laser ablation Methods 0.000 description 3
- 238000001451 molecular beam epitaxy Methods 0.000 description 3
- 230000000704 physical effect Effects 0.000 description 3
- 229910010271 silicon carbide Inorganic materials 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000010894 electron beam technology Methods 0.000 description 2
- 238000000609 electron-beam lithography Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000005543 nano-size silicon particle Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 239000000956 alloy Substances 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 238000003486 chemical etching Methods 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000001127 nanoimprint lithography Methods 0.000 description 1
- 238000007146 photocatalysis Methods 0.000 description 1
- 230000001699 photocatalysis Effects 0.000 description 1
- 238000005424 photoluminescence Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000001338 self-assembly Methods 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 230000005476 size effect Effects 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
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- 239000004575 stone Substances 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/02—Silicon
- C01B33/021—Preparation
- C01B33/023—Preparation by reduction of silica or free silica-containing material
-
- 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
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
Abstract
The invention provides a silicon nanowire, a preparation method and application thereof, wherein a silicon source is evaporated once to obtain silicon vapor; performing secondary evaporation on an aluminum source to obtain aluminum vapor; introducing the silicon vapor into aluminum vapor at a speed of 2-5g/min to react, so as to obtain a silicon nanowire; according to the preparation method of the silicon nanowire, aluminum with low melting point and reducibility is used as a silicon nanowire control agent, and the cost is controllable; and the preparation method has simple and reliable working procedures and is convenient for large-scale mass production.
Description
Technical Field
The invention belongs to the field of lithium batteries, and particularly relates to a silicon nanowire and a preparation method and application thereof.
Background
The nanoscale material has a series of physical effects such as quantum size effect, macroscopic quantum tunneling effect, coulomb blocking effect, small-size effect, volume effect and the like, and the silicon nanowire has all physical effects of the nanomaterial, is the first representative of semiconductor nanomaterial, has special properties in the semiconductor field, also has physical properties different from bulk silicon materials, such as field emission, visible photoluminescence, thermal conductivity and the like, and has good application markets in the aspects of sensors, field effect transistors, photocatalysis, batteries and the like.
Compared with the traditional graphite anode material, silicon has extremely high mass specific capacity 4200mAh/g, and compared with metal lithium, silicon also has extremely high volume specific capacity because the bulk density of silicon in an alloy material is similar to that of lithium. Compared with nano silicon particles, the silicon nanowire has the advantages that the transverse volume effect is not obvious in the lithium intercalation and deintercalation process, and the silicon nanowire cannot be crushed to lose electrical contact like nano silicon particles, so that the cycling stability is better.
At present, there are a plurality of preparation methods of silicon nanowires, mainly comprising: chemical Vapor Deposition (CVD), molecular beam epitaxy (MEB), laser Ablation (LA), oxide assist (OGA), solution method, etching method, and the like, the preparation methods thereof can be classified into two types, i.e., a "top-down" and a "bottom-up" technique, according to the growth mode of the silicon nanowire.
The mode of continuously depositing and growing the nano structure from the atomic layer through a self-assembly mode is mainly comprising chemical vapor deposition, molecular beam epitaxy, laser ablation, an oxide auxiliary method, a solution method and the like. Firstly, etching pretreatment is carried out on a template from top to bottom, and a sample is etched and candled into a growth mode of a nano structure with a desired size; it is analogous to engraving with stone, the substrate is gradually eroded, eventually reaching the desired shape. Methods include Electron Beam Lithography (EBL), nanoimprint lithography, and metal assisted chemical etching techniques.
CN110950323a discloses a carbon nanotube-silicon carbide nanowire composite material, which is a one-dimensional nanostructure, and in the material, silicon carbide nanowires grow along the length direction of the carbon nanotubes. The preparation method of the material comprises the following steps: placing the pretreated substrate into a tube furnace, and depositing carbon nanotubes on the substrate by adopting a chemical vapor deposition method; and then depositing silicon carbide nano wires on the carbon nano tubes by adopting a chemical vapor deposition method to obtain the carbon nano tube-silicon carbide nano wire composite material. The method fully utilizes the fact that the carbon nano tube and the silicon carbide nano wire both follow a V-L-S growth mechanism when being prepared in a CVD mode, so that a brand new one-dimensional nano structure material is prepared.
CN107445167a discloses a preparation method of ultra-long silicon carbide nanowires, which comprises the following steps: dispersing silicon oxide and organic carbon in absolute ethyl alcohol according to the weight ratio of 1:2-2:1, evaporating the absolute ethyl alcohol and drying, uniformly mixing reduced iron powder and silicon oxide according to the weight ratio of 1:5-20, placing the mixture in a porcelain boat, placing the porcelain boat in a tubular furnace filled with argon atmosphere, sintering the porcelain boat for 1-4h at the temperature of 1000-1400 ℃, finally soaking the porcelain boat in hydrofluoric acid for 2h, washing, centrifuging and drying to obtain the silicon carbide nanowire. The method uses SiO as a reactant and a template, uses a series of materials for providing a carbon source as a reducing agent and a structural support, uses iron as a catalyst, and prepares the silicon carbide nanowire by a co-reduction method with the iron.
CN1590599a is a method for preparing silicon nanowires, comprising: (1) Preparation of silicon source for evaporation silicon (Si) powder with 99.99% purity and silicon dioxide (SiO) with 99.99% purity 2 ) Powder, the weight ratio of which is 1:1, uniformly stirring, and then using a tablet press to make Si+SiO 2 Pressing the powder into a sheet, and vacuumizing in a source crucible of an ultrahigh vacuum electron beam system for standby; (2) SiO of 100-600 nm is selected for preparing the growth substrate of the silicon nano wire 2 Si (111) or SiO 2 As a growth substrate for the silicon nanowire, the silicon nanowire is grown in vacuum.
However, the prior art has certain disadvantages, such as high raw material requirement and purity reaching 99.99% often; the process is complex, and silicon powder and silicon dioxide powder are required to be mixed and pressed into tablets; expensive equipment such as high vacuum, electron beam and the like is required; the growth efficiency is low.
Therefore, there is a need for a method for producing silicon nanowires that has low raw material requirements, is cost-effective, has simple and reliable processes, and facilitates mass production.
Disclosure of Invention
The invention aims to provide a silicon nanowire, a preparation method and application thereof, wherein a silicon source is evaporated once to obtain silicon vapor; performing secondary evaporation on an aluminum source to obtain aluminum vapor; introducing the silicon vapor into aluminum vapor at a speed of 2-5g/min to react, so as to obtain a silicon nanowire; according to the preparation method of the silicon nanowire, aluminum with low melting point and reducibility is used as a silicon nanowire control agent, and the cost is controllable; and the preparation method has simple and reliable working procedures and is convenient for large-scale mass production.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
one of the purposes of the invention is to provide a preparation method of a silicon nanowire, which comprises the following steps:
(1) Evaporating a silicon source for the first time to obtain silicon vapor;
(2) Performing secondary evaporation on an aluminum source to obtain aluminum vapor;
(3) And introducing the silicon vapor into aluminum vapor at a speed of 2-5g/min to react, so as to obtain the silicon nanowire.
In the invention, aluminum with lower melting point and reducibility is used as a control agent for the growth of the silicon nanowires, and plays a role in catalysis, the silicon nanowires grow when silicon vapor and aluminum vapor meet, the requirement on the purity of raw materials is low, and the cost is controllable; and the preparation method has simple and reliable working procedures and is convenient for large-scale mass production.
In the step (3), the speed of introducing the silicon vapor into the aluminum vapor is 2-5g/min, for example, 2g/min,2.2g/min,2.4g/min,2.6g/min,2.8g/min,3g/min,3.2g/min,3.4g/min,3.6g/min,3.8g/min,4g/min,4.2g/min,4.4g/min,4.6g/min,4.8g/min,5g/min and the like; the speed of introducing the silicon vapor into the aluminum vapor is 2-5g/min, and if the speed is higher than 5g/min, the diameter of the silicon nanowire is thicker and the length of the silicon nanowire is shorter; if it is less than 2g/min, the silicon nanowire is thin and short in length.
In a preferred embodiment of the present invention, the purity of the silicon source in the step (1) is not less than 95%, for example, 95%,95.5%,96%,96.5%,97%,97.5%,98%,98.5%,99%,99.5%,99.9%, etc., but the present invention is not limited to the above-mentioned values, and other values not shown in the above-mentioned ranges are applicable.
Preferably, the silicon source of step (1) comprises any one or a combination of at least two of silicon powder, silicon chunks, silicon dioxide or silicon oxide, typical but non-limiting examples of which include a combination of silicon powder and silicon chunks, a combination of silicon powder and silicon dioxide, a combination of silicon powder and silicon oxide, a combination of silicon chunks and silicon dioxide, a combination of silicon chunks and silicon oxide, a combination of silicon dioxide and silicon oxide.
In a preferred embodiment of the present invention, the temperature of the primary evaporation in the step (1) is 1600 to 2000 ℃, for example, 1600 ℃,1650 ℃,1700 ℃,1750 ℃,1800 ℃,1850 ℃,1900 ℃,2000 ℃, etc., but the present invention is not limited to the above-mentioned values, and other values not mentioned in the above-mentioned numerical ranges are equally applicable.
As a preferred embodiment of the present invention, the aluminum source in step (2) includes any one or a combination of at least two of aluminum plate, aluminum powder, or aluminum wire, and typical but non-limiting examples of the combination include a combination of aluminum plate and aluminum powder, a combination of aluminum plate and aluminum wire, and a combination of aluminum powder and aluminum wire.
Preferably, the surface of the aluminum source in the step (2) contains a plating layer.
Preferably, the material of the plating layer comprises gold and/or silver.
In a preferred embodiment of the present invention, the temperature of the secondary evaporation in the step (2) is 500 to 800 ℃, for example, 500 ℃,520 ℃,550 ℃,580 ℃,600 ℃,630 ℃,650 ℃,670 ℃,700 ℃,730 ℃,50 ℃,780 ℃,800 ℃, etc., but the present invention is not limited to the above-mentioned values, and other values not mentioned in the above-mentioned numerical ranges are applicable.
Preferably, the secondary evaporation in step (2) is performed in an argon atmosphere.
In a preferred embodiment of the present invention, the temperature of the reaction in the step (3) is 500 to 800 ℃, for example, 500 ℃,520 ℃,550 ℃,580 ℃,600 ℃,630 ℃,650 ℃,670 ℃,700 ℃,730 ℃,50 ℃,780 ℃,800 ℃, etc., but the present invention is not limited to the above-mentioned values, and other values not mentioned in the above-mentioned numerical ranges are applicable.
Preferably, the reaction time in step (3) is 1-5h, for example, but not limited to, 1h,1.2h,1.5h,1.8h,2h,2.3h,2.5h,2.7h,3h,3.2h,3.5h,3.8h,4h,4.2h,4.5h,4.7h,5h, etc., and other non-enumerated values in the above range are equally applicable.
As a preferable technical scheme of the invention, the preparation method comprises the following steps:
(1) Heating a silicon source with purity of more than or equal to 95% to 1600-2000 ℃ for primary evaporation to obtain silicon vapor;
wherein the silicon source comprises any one or a combination of at least two of silicon powder, silicon blocks, silicon dioxide or silicon oxide;
(2) Heating an aluminum source to 500-800 ℃ and performing secondary evaporation under argon atmosphere to obtain aluminum vapor;
wherein the aluminum source comprises any one or a combination of at least two of aluminum plates, aluminum powder or aluminum wires; the surface of the aluminum source contains gold and/or silver plating layers;
(3) And introducing silicon vapor into aluminum vapor at a speed of 2-5g/min to react for 1-5h at 500-800 ℃ to obtain the silicon nanowire.
It is a second object of the present invention to provide a silicon nanowire having a diameter of < 200nm and a length of > 100 μm, obtained by the method of preparation according to one of the objects.
The invention further aims to provide an application of the second silicon nanowire, and the silicon nanowire is used for preparing a lithium battery negative electrode plate.
The numerical ranges recited herein include not only the above-listed point values, but also any point values between the above-listed numerical ranges that are not listed, and are limited in space and for the sake of brevity, the present invention is not intended to be exhaustive of the specific point values that the stated ranges include.
Compared with the prior art, the invention has the following beneficial effects:
(1) The preparation method of the silicon nanowire has low requirement on the purity of raw materials, uses aluminum with lower melting point and reducibility as a silicon nanowire control agent, and has controllable cost;
(2) The preparation method of the silicon nanowire has simple and reliable working procedures and is convenient for large-scale mass production.
Drawings
FIG. 1 is a schematic view of an evaporation reaction apparatus according to the present invention;
wherein, 1-evaporating chamber; 2-a reaction chamber; 3-piping; a 4-silicon source; a 5-aluminum source;
FIG. 2 is a scanning electron microscope image with a magnification of 20000 of the silicon nanowires according to embodiment 1 of the present invention;
fig. 3 is a scanning electron microscope image with a magnification of 1000 for the silicon nanowire according to example 1 of the present invention.
Detailed Description
The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
It should be noted that, in the specific embodiment of the present invention, the evaporation reaction device shown in fig. 1 is adopted, and the evaporation reaction device includes an evaporation chamber 1 and a reaction chamber 2, where the evaporation chamber and the reaction chamber are connected through a pipeline 3; 1, evaporating a silicon source 4 for one time to obtain silicon vapor; performing secondary evaporation on the aluminum source 5 to obtain aluminum vapor; the silicon vapor is introduced into the reaction chamber 2 through the pipe 3 to react with the aluminum vapor, thereby obtaining silicon nanowires, and the direction of the arrow in fig. 1 represents the flow direction of the silicon vapor.
Example 1
The embodiment provides a silicon nanowire and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) 3kg of silicon dioxide with purity of 98% is heated to 1800 ℃ for one-time evaporation to obtain silicon dioxide vapor;
(2) Heating an aluminum plate with a silver coating on the surface to 700 ℃ and performing secondary evaporation in an argon atmosphere to obtain aluminum vapor;
(3) And introducing silicon dioxide vapor into aluminum vapor at a speed of 2g/min, and reacting at 750 ℃ for 3 hours to obtain the silicon nanowire.
The scanning electron microscope image with the magnification of 20000 of the silicon nanowire obtained in the embodiment is shown in fig. 2, and as can be seen from fig. 2, the diameter of the silicon nanowire obtained in the embodiment is about 100-200nm; fig. 3 is a scanning electron microscope image with a magnification of 1000 for the silicon nanowire obtained in this embodiment, and as can be seen from fig. 3, the silicon nanowire produced in this embodiment is relatively uniform.
Example 2
The embodiment provides a silicon nanowire and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) Heating 2kg of silicon powder with purity of 95% to 2000 ℃ for one-time evaporation to obtain silicon vapor;
(2) Heating an aluminum block with a gold plating layer on the surface to 800 ℃ and performing secondary evaporation in an argon atmosphere to obtain aluminum vapor;
(3) And (3) introducing silicon vapor into aluminum vapor at a speed of 5g/min, and reacting at 800 ℃ for 1h to obtain the silicon nanowire.
Example 3
The embodiment provides a silicon nanowire and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) Heating 1kg of silicon powder with the purity of 96% and 2kg of silicon dioxide with the purity of 96% to 1700 ℃ for one-time evaporation to obtain silicon vapor;
(2) Heating an aluminum plate with a silver coating on the surface to 600 ℃, and performing secondary evaporation under argon atmosphere to obtain aluminum vapor;
(3) And (3) introducing silicon vapor into aluminum vapor at a speed of 3g/min, and reacting at 600 ℃ for 2 hours to obtain the silicon nanowire.
Example 4
The embodiment provides a silicon nanowire and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) Heating 2.1kg of silicon blocks with purity of 97.2% to 1600 ℃ for one-time evaporation to obtain silicon vapor;
(2) Heating an aluminum plate with a gold coating on the surface to 500 ℃ and performing secondary evaporation in an argon atmosphere to obtain aluminum vapor;
(3) And (3) introducing silicon vapor into aluminum vapor at a speed of 3g/min, and reacting at 500 ℃ for 5 hours to obtain the silicon nanowire.
Example 5
The embodiment provides a silicon nanowire and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) Heating 1.5kg of silicon powder with the purity of 98.1% and 1kg of silicon dioxide with the purity of 98% to 1850 ℃ for primary evaporation to obtain silicon vapor;
(2) Heating an aluminum plate with a gold coating on the surface to 650 ℃, and performing secondary evaporation under argon atmosphere to obtain aluminum vapor;
(3) And introducing silicon vapor into aluminum vapor at a speed of 4g/min, and reacting at 650 ℃ for 2.5h to obtain the silicon nanowire.
Comparative example 1
This comparative example provides a silicon nanowire and a method for preparing the same, which is different only in that, referring to the preparation method described in example 1: the rate of silicon vapor flow into the aluminum vapor was replaced by 1g/min from 2 g/min.
Comparative example 2
This comparative example provides a silicon nanowire and a method for preparing the same, which is different only in that, referring to the preparation method described in example 1: the rate of silicon vapor flow into the aluminum vapor was replaced by 6g/min from 2 g/min.
The silicon nanowires obtained in the above examples and comparative examples were tested for size and yield by the following test methods:
size: measuring the average diameter of the silicon nanowires by a Scanning Electron Microscope (SEM); the average length of the silicon nanowires is measured by image pro plus 6.0;
yield: weighing the mass M of the obtained silicon nanowire and the mass M of the silicon source which is initially input 0 The ratio of (2) is the yield, i.e. yield = M/M 0 ×100％。
The test results of the silicon nanowires obtained in the above examples and comparative examples are shown in table 1.
TABLE 1
| Project | Average diameter/nm | Average length/μm | Theoretical yield/% | Yield/% |
| Example 1 | 146 | 178.3 | 53.3 | 48.3 |
| Example 2 | 152.3 | 187.1 | 100 | 98.5 |
| Example 3 | 147.3 | 177.2 | 68.9 | 65.2 |
| Example 4 | 158.3 | 195.3 | 100 | 98.1 |
| Example 5 | 149.6 | 182.1 | 81.3 | 77.6 |
| Comparative example 1 | 136.5 | 149.4 | 100 | 97.0 |
| Comparative example 2 | 164.1 | 136.3 | 100 | 92.2 |
It is worth noting that the theoretical yield is the mass ratio of silicon element in the raw material.
From table 1, the following points can be found:
(1) It can be seen from examples 1 to 5 that the silicon nanowire obtained by the preparation method of the silicon nanowire of the present invention has an average diameter of about 150nm and an average length of about 180 um;
(2) Comparing example 1 with comparative examples 1 and 2, it was found that the average diameter of the silicon nanowire becomes smaller and the average length becomes shorter because the velocity of the silicon vapor introduced into the aluminum vapor in comparative example 1 is 1g/min, which is lower than the preferred 2-5g/min of the present invention; since the speed of introducing the silicon vapor into the aluminum vapor in comparative example 2 was 6g/min, which exceeds the preferred 2-5g/min of the present invention, the average diameter of the silicon nanowires was increased and the average length was shortened.
The applicant declares that the above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that are easily conceivable within the technical scope of the present invention disclosed by the present invention fall within the scope of the present invention and the disclosure.
Claims (10)
1. A method for preparing a silicon nanowire, comprising the steps of:
(1) Evaporating a silicon source for the first time to obtain silicon vapor;
(2) Performing secondary evaporation on an aluminum source to obtain aluminum vapor;
(3) And introducing the silicon vapor into aluminum vapor at a speed of 2-5g/min to react, so as to obtain the silicon nanowire.
2. The method for producing a silicon nanowire according to claim 1, wherein the purity of the silicon source in step (1) is not less than 95%;
preferably, the silicon source of step (1) comprises any one or a combination of at least two of silicon powder, silicon block, silicon dioxide or silicon oxide.
3. The method of preparing silicon nanowires according to claim 1 or 2, wherein the temperature of the one evaporation in step (1) is 1600-2000 ℃.
4. A method of producing silicon nanowires according to any of claims 1 to 3, wherein the aluminium source of step (2) comprises any one or a combination of at least two of aluminium plate, aluminium powder or aluminium wire;
preferably, the surface of the aluminum source in the step (2) contains a plating layer;
preferably, the material of the plating layer comprises gold and/or silver.
5. The method of producing silicon nanowires according to any of claims 1 to 4, wherein the temperature of the secondary evaporation in step (2) is 500 to 800 ℃;
preferably, the secondary evaporation in step (2) is performed in an argon atmosphere.
6. The method of producing silicon nanowires as recited in any one of claims 1 to 5, wherein the temperature of the reaction in the step (3) is 500 to 800 ℃.
7. The method of producing silicon nanowires according to any one of claims 1 to 6, wherein the reaction time of step (3) is 1 to 5 hours.
8. A method of preparing a silicon nanowire according to any one of claims 1-7, characterized in that the preparation method comprises the steps of:
(1) Heating a silicon source with purity of more than or equal to 95% to 1600-2000 ℃ for primary evaporation to obtain silicon vapor;
wherein the silicon source comprises any one or a combination of at least two of silicon powder, silicon blocks, silicon dioxide or silicon oxide;
(2) Heating an aluminum source to 500-800 ℃ and performing secondary evaporation under argon atmosphere to obtain aluminum vapor;
wherein the aluminum source comprises any one or a combination of at least two of aluminum plates, aluminum powder or aluminum wires; the surface of the aluminum source contains gold and/or silver plating layers;
(3) And (3) introducing silicon vapor into aluminum vapor at a speed of 2-5g/min, and reacting at 500-800 ℃ for 1-5h to obtain the silicon nanowire.
9. A silicon nanowire obtainable by the method according to any one of claims 1 to 8, characterized in that the diameter of the silicon nanowire is < 200nm and the length is > 100 μm.
10. Use of the silicon nanowire according to claim 9 for preparing a negative electrode sheet of a lithium battery.
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