CN111874911A - Preparation method of amorphous silicon material - Google Patents
Preparation method of amorphous silicon material Download PDFInfo
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- 229910021417 amorphous silicon Inorganic materials 0.000 title claims abstract description 57
- 239000002210 silicon-based material Substances 0.000 title claims abstract description 51
- 238000002360 preparation method Methods 0.000 title abstract description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 121
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 53
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 52
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 40
- 239000002994 raw material Substances 0.000 claims abstract description 29
- 239000002131 composite material Substances 0.000 claims abstract description 28
- 238000000034 method Methods 0.000 claims abstract description 27
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000004408 titanium dioxide Substances 0.000 claims abstract description 20
- YHWCPXVTRSHPNY-UHFFFAOYSA-N butan-1-olate;titanium(4+) Chemical compound [Ti+4].CCCC[O-].CCCC[O-].CCCC[O-].CCCC[O-] YHWCPXVTRSHPNY-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000001035 drying Methods 0.000 claims abstract description 16
- 239000012535 impurity Substances 0.000 claims abstract description 14
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims abstract description 6
- 239000002253 acid Substances 0.000 claims abstract description 4
- 230000003301 hydrolyzing effect Effects 0.000 claims abstract description 4
- 238000005406 washing Methods 0.000 claims abstract description 4
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 40
- 150000003841 chloride salts Chemical class 0.000 claims description 32
- 239000000243 solution Substances 0.000 claims description 32
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 claims description 26
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 24
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 20
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 20
- 229910052786 argon Inorganic materials 0.000 claims description 20
- 238000006243 chemical reaction Methods 0.000 claims description 16
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 13
- 238000006460 hydrolysis reaction Methods 0.000 claims description 13
- 229910052710 silicon Inorganic materials 0.000 claims description 13
- 239000010703 silicon Substances 0.000 claims description 13
- 239000007789 gas Substances 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 12
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 10
- 239000007795 chemical reaction product Substances 0.000 claims description 10
- 239000001257 hydrogen Substances 0.000 claims description 10
- 229910052739 hydrogen Inorganic materials 0.000 claims description 10
- 238000002156 mixing Methods 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 10
- 239000005543 nano-size silicon particle Substances 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 6
- 238000002791 soaking Methods 0.000 claims description 6
- 239000003365 glass fiber Substances 0.000 claims description 5
- 235000007164 Oryza sativa Nutrition 0.000 claims description 4
- 239000006229 carbon black Substances 0.000 claims description 4
- 239000011521 glass Substances 0.000 claims description 4
- 235000009566 rice Nutrition 0.000 claims description 4
- 239000002689 soil Substances 0.000 claims description 4
- 239000002699 waste material Substances 0.000 claims description 4
- 239000004576 sand Substances 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 2
- 240000007594 Oryza sativa Species 0.000 claims 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 8
- 239000007772 electrode material Substances 0.000 abstract description 8
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 8
- 239000000463 material Substances 0.000 abstract description 7
- 229910052782 aluminium Inorganic materials 0.000 abstract description 4
- 229910052751 metal Inorganic materials 0.000 abstract description 4
- 239000002184 metal Substances 0.000 abstract description 4
- 238000007133 aluminothermic reaction Methods 0.000 abstract 1
- 239000010406 cathode material Substances 0.000 abstract 1
- 238000011031 large-scale manufacturing process Methods 0.000 abstract 1
- 239000002086 nanomaterial Substances 0.000 abstract 1
- 239000000376 reactant Substances 0.000 description 10
- 238000001816 cooling Methods 0.000 description 9
- 239000011261 inert gas Substances 0.000 description 8
- 238000000926 separation method Methods 0.000 description 8
- 239000000047 product Substances 0.000 description 7
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 4
- 229910021419 crystalline silicon Inorganic materials 0.000 description 4
- 239000007773 negative electrode material Substances 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 3
- 241000209094 Oryza Species 0.000 description 3
- 229910052744 lithium Inorganic materials 0.000 description 3
- 238000004098 selected area electron diffraction Methods 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 238000003917 TEM image Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 238000006138 lithiation reaction Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002077 nanosphere Substances 0.000 description 2
- 239000001103 potassium chloride Substances 0.000 description 2
- 235000011164 potassium chloride Nutrition 0.000 description 2
- 239000011241 protective layer Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 description 1
- 239000006245 Carbon black Super-P Substances 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910001290 LiPF6 Inorganic materials 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 238000001755 magnetron sputter deposition Methods 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
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- 239000013307 optical fiber Substances 0.000 description 1
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- 238000011056 performance test Methods 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical class [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 235000010413 sodium alginate Nutrition 0.000 description 1
- 239000000661 sodium alginate Substances 0.000 description 1
- 229940005550 sodium alginate Drugs 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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Images
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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/386—Silicon or alloys based on silicon
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention relates to a preparation method of an amorphous silicon material, belonging to the technical field of lithium ion battery electrode materials. The process comprises the steps of hydrolyzing tetrabutyl titanate coated by a silicon dioxide material to form a silicon dioxide/titanium dioxide composite material, reacting the silicon dioxide/titanium dioxide composite material with metal aluminum in chloride, removing impurities by acid washing, and drying to obtain the amorphous silicon electrode material. The invention has the advantages of rich sources of silicon dioxide raw materials, simple technical process and large-scale production. Compared with the traditional aluminothermic reaction, the preparation method can obtain better amorphous silicon nano-materials and better keep the original shape of silicon dioxide. The lithium ion battery cathode material has excellent electrochemical performance and wide application value.
Description
Technical Field
The invention relates to a preparation method of an amorphous silicon material, belonging to the technical field of lithium ion battery electrode materials.
Background
With the rapid development of electronic devices and electric automobiles, the technical breakthrough of lithium ion batteries becomes a problem which needs to be solved urgently, so that the preparation of electrode materials becomes a hot research topic. Among these, silicon has been studied in recent years in large quantities for a new generation of lithium ion batteries because of its high energy density as a negative electrode material. Compared with the theoretical capacity (372mAh/g) of the traditional graphite, the silicon has the specific capacity (4200mAh/g) which is 10 times larger than that of the traditional graphite, and the characteristics of abundant resources and high safety of the silicon make the silicon more popular with researchers.
However, the silicon negative electrode material has very significant defects, and during the charging and discharging processes, silicon undergoes huge volume expansion (> 300%), so that the active material is cracked and easily falls off from the current collector during the lithiation process, and thus loses activity, and the electrochemical performance is deteriorated. In order to solve the above problems, researchers have been increasingly focusing on amorphous silicon in recent years. Amorphous silicon is only isotropically strained/stressed during lithiation/delithiation and is therefore more resistant to cracking due to volume expansion than crystalline silicon. In addition, amorphous silicon has a higher operating potential than crystalline silicon (amorphous: 0.22V; crystalline: 0.12V), and thus the problems of lithium dendrites and volume expansion can be effectively suppressed by increasing the cut-off potential.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a preparation method of an amorphous silicon material, which has a simple and convenient process, and the preparation method comprises the steps of coating titanium dioxide on a silicon dioxide material by using a method for hydrolyzing tetrabutyl titanate to form a silicon dioxide/titanium dioxide composite material, reacting the silicon dioxide/titanium dioxide composite material with metal aluminum in chloride, removing impurities by acid washing, and drying to obtain the amorphous silicon electrode material. In the traditional aluminothermic reduction method, the generated silicon product is in a fine nano-particle shape, the original shape of the silicon dioxide raw material cannot be maintained, and the silicon nano-particle has a high crystallization degree. According to the invention, through the chemical adsorption and hydrolysis processes of tetrabutyl titanate, a titanium dioxide protective layer is pre-coated on the surface of silicon dioxide, and chloride is added in the reduction process, so that excessive heat generated in the reaction process is effectively absorbed, the contact area of reactants is greatly increased, the reaction is more efficient and uniform, the structural damage in the reaction process is greatly relieved, the product keeps the shape of the silicon dioxide raw material, and a large amount of amorphous state in the silicon product is formed. Provides a good preparation scheme for preparing amorphous silicon electrode materials. Meanwhile, various raw materials with different shapes, such as nano silicon dioxide ball powder, diatomite, white carbon black, rice hull ash, glass fiber waste, sand, sandy soil and powder after glass ball milling, are utilized, so that the utilization rate of some waste materials is greatly improved, and the shapes of final products are diversified.
In order to achieve the above object, the present invention adopts the following technical solutions:
and hydrolyzing tetrabutyl titanate coated by a silicon dioxide material to form a silicon dioxide/titanium dioxide composite material, reacting the silicon dioxide/titanium dioxide composite material with metal aluminum in chloride, removing impurities by acid washing, and drying to obtain the amorphous silicon electrode material.
The method specifically comprises the following steps:
(1) uniformly soaking a silicon dioxide raw material into an ethanol solution of tetrabutyl titanate, separating, performing hydrolysis reaction at normal temperature, and drying to obtain a silicon dioxide/titanium dioxide composite material;
(2) adding aluminum powder and chloride salt into the composite material prepared in the step (1), uniformly mixing, heating to react in an inert atmosphere, and cooling to obtain a reactant;
(3) and (3) sequentially immersing the reaction product into sufficient hydrochloric acid aqueous solution and hydrofluoric acid solution to remove impurities, and separating and drying to obtain the amorphous silicon material.
Further, the silica raw material in the step (1) is one or more of nano silica ball powder, diatomite, white carbon black, rice hull ash, glass fiber waste, sand, sandy soil and powder of ball-milled glass.
Further, the molar concentration of the ethanol solution of tetrabutyl titanate in the step (1) is 100-800 mmol/L.
Further, the hydrolysis reaction condition in the step (1) is reaction for 1-5 minutes at normal temperature.
Further, the inert atmosphere in the step (2) is pure argon gas, or a mixed gas of hydrogen (5 v%) and argon (95 v%).
Further, the chloride salt in the step (2) is aluminum chloride or a mixture of the aluminum chloride and other chloride salts.
Further, the molar ratio of the aluminum powder and the chloride salt in the step (2) to the silicon dioxide in the silicon dioxide raw material in the step (1) is 1.28: 2: 3: 0.5 to 1.
Further, the heating reaction condition in the step (2) is that the reaction temperature is 250-350 ℃, and the reaction is carried out for 3-12 hours at constant temperature.
Furthermore, the silicon product in the amorphous silicon material finally prepared by the invention is nanospheres with uniform size and complete appearance. The amorphous silicon material prepared by the invention contains nano silicon spheres; the diameter of the nano silicon spheres in the whole amorphous silicon material is about 200 nm. Further applied, the finally prepared amorphous silicon material is used as a lithium ion battery negative electrode material, is uniformly mixed with a commercially available Super-P conductive agent and a sodium alginate binder according to a mass ratio of 60:20:20, is coated on a current collector copper foil, is dried at 60 ℃ in a vacuum box, is prepared into an electrode plate with the diameter of 1.2cm by a tablet press, and is dried for 12 hours in vacuum at 80 ℃. Using a metal lithium sheet as a counter electrode, adopting Celgard 2400 as a diaphragm and 1mol/L LiPF6+ EC + DEC (EC: DEC volume ratio 1:1) containing 10 vol% FEC as electrolyte in a glove box (H)2O<1ppm,O2<1ppm) and electrochemical performance test is carried out by adopting a blue CT2001A type battery tester, and the charge-discharge cut-off voltage is 0.005-1V (vs. Li)+/Li) The test temperature is 25 ℃, and the test result shows that the first cycle specific capacity of the electrode material can reach 2763.3mAh g-1The first coulombic efficiency is 78.6 percent, and the material has excellent rate capability of 0.5,1,1.5,2,2.5,3,4A g-1The specific capacity respectively reaches 2800,2494,2274,2050,1865,1755,1604mAh g under the current density-1At 4A g-1The specific capacity can still reach 1339mAh g after the current density is cycled for 500 weeks-1。
Compared with the prior art, the invention has the following characteristics:
1) compared with the traditional aluminothermic reduction method, the method can better ensure that the silicon product keeps the unique appearance of the raw material, and the prepared material has uniform size and complete structure.
2) The prepared silicon material has a better amorphous state, so that the silicon material can better relieve the volume expansion in the electrode circulation process compared with crystalline silicon, and provides excellent electrochemical performance in the application of lithium ion batteries.
Drawings
FIG. 1 is a schematic process flow diagram of an amorphous silicon material prepared by the method of the present invention.
FIG. 2 is a scanning electron microscope spectrum of an amorphous silicon material prepared in example 1 of the present invention;
FIG. 3 is a transmission electron microscope (FIG. 3a) and a selected area electron diffraction (FIG. 3b) of an amorphous silicon material prepared according to example 1 of the present invention;
fig. 4 is a graph of electrochemical rate performance and coulombic efficiency of the amorphous silicon material prepared in example 1 of the present invention. The horizontal coordinate is the cycle number of weeks, and the unit is week; the left ordinate is the specific discharge capacity, in units: milliampere hour gram-1(mAh g-1) The right ordinate is coulombic efficiency in units: percentage (%).
Fig. 5 is a graph of electrochemical cycling performance and coulombic efficiency of amorphous silicon material prepared in example 1 of the present invention. The horizontal coordinate is the cycle number of weeks, and the unit is week; the left ordinate is the specific discharge capacity, in units: milliampere hour gram-1(mAh g-1) Right side longitudinal seatDenoted coulombic efficiency in units of: percentage (%).
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
Example 1:
the amorphous silicon material prepared in this example specifically includes the following steps, as shown in fig. 1:
(1) uniformly immersing a silicon dioxide raw material into 100 mmol/L ethanol solution of tetrabutyl titanate, chemically adsorbing tetrabutyl titanate on the surface of the silicon dioxide material through the combination with hydroxyl, carrying out hydrolysis reaction for 1 minute at normal temperature after separation to obtain an extremely thin titanium dioxide protective layer, and drying to obtain the silicon dioxide/titanium dioxide composite material.
(2) Adding aluminum powder and chloride salt into the composite material prepared in the step (1), uniformly mixing, heating to 300 ℃ in an inert atmosphere, preserving heat for 12 hours, and cooling to obtain a reactant. The added chloride mixture forms a molten state at high temperature, absorbs excessive heat generated in the reaction, greatly increases the contact area of reaction raw materials, makes the reaction more uniform, plays a good role in buffering, and greatly relieves the structural damage in the reaction process.
(3) The reaction product was immersed in a sufficient amount of 3mol/l aqueous hydrochloric acid solution and 5 wt% hydrofluoric acid solution in this order to remove impurities, and then separated and dried to obtain an amorphous silicon material.
The chloride salt in the step (2) is a mixture of sodium chloride and aluminum chloride.
The molar ratio of the aluminum powder and the chloride salt in the step (2) to the silicon dioxide in the silicon dioxide raw material in the step (1) is 1.28: 2: 3: 0.68.
the inert gas in the step (2) is pure argon or a mixed gas of argon (95 v%) and hydrogen (5 v%).
Fig. 2 is a scanning electron microscope image of the amorphous silicon material prepared in this example, which shows that the prepared amorphous silicon material maintains a uniform and complete nano-sphere shape, and the diameter is about 200 nm;
FIG. 3 is a transmission electron micrograph and a selected area electron diffraction pattern of the amorphous silicon material prepared in this example. Fig. 3a is a transmission electron micrograph also showing the structural integrity and homogeneity of the amorphous silicon material produced. FIG. 3b is a selected area electron diffraction pattern of the material, demonstrating that the silicon material produced has a large amount of amorphous state.
As shown in fig. 4 and 5, when the amorphous silicon material prepared in this example is used as the negative electrode material of the lithium ion battery, the values are 0.5,1,1.5,2,2.5,3,4A g-1The specific capacity respectively reaches 2800,2494,2274,2050,1865,1755,1604mAh g under the current density-1. At 4A g-1After 500 times of circulation under high current density, the specific capacity can be kept at 1339mAh g-1The above.
Example 2:
the amorphous silicon material prepared in this embodiment specifically includes the following steps:
(1) the diatomite raw material is evenly immersed into 200 millimole/liter ethanol solution of tetrabutyl titanate, after separation, hydrolysis reaction is carried out for 3 minutes at normal temperature, and after drying, the silicon dioxide/titanium dioxide composite material is prepared.
(2) Adding aluminum powder and chloride salt into the composite material prepared in the step (1), uniformly mixing, heating to 350 ℃ in an inert atmosphere, preserving heat for 6 hours, and cooling to obtain a reactant.
(3) The reaction product was immersed in a sufficient amount of 3mol/l aqueous hydrochloric acid solution and 5 wt% hydrofluoric acid solution in this order to remove impurities, and then separated and dried to obtain an amorphous silicon material.
The chloride salt in the step (2) is aluminum chloride.
The molar ratio of the aluminum powder and the chloride salt in the step (2) to the silicon dioxide in the silicon dioxide raw material in the step (1) is 1.28: 3: 0.5.
the inert gas in the step (2) is pure argon or a mixed gas of argon (95 v%) and hydrogen (5 v%).
Example 3:
the amorphous silicon material prepared in this embodiment specifically includes the following steps:
(1) uniformly soaking the white carbon black raw material into 300 millimole/liter ethanol solution of tetrabutyl titanate, carrying out hydrolysis reaction for 5 minutes at normal temperature after separation, and drying to obtain the silicon dioxide/titanium dioxide composite material.
(2) Adding aluminum powder and chloride salt into the composite material prepared in the step (1), uniformly mixing, heating to 250 ℃ in an inert atmosphere, keeping the temperature for 12 hours, and cooling to obtain a reactant.
(3) The reaction product was immersed in a sufficient amount of 3mol/l aqueous hydrochloric acid solution and 5 wt% hydrofluoric acid solution in this order to remove impurities, and then separated and dried to obtain an amorphous silicon material.
The chloride salt in the step (2) is a mixture of potassium chloride and aluminum chloride.
The molar ratio of the aluminum powder and the chloride salt in the step (2) to the silicon dioxide in the silicon dioxide raw material in the step (1) is 1.28: 2: 3: 0.8.
the inert gas in the step (2) is pure argon or a mixed gas of argon (95 v%) and hydrogen (5 v%).
Example 4:
the amorphous silicon material prepared in this embodiment specifically includes the following steps:
(1) uniformly soaking the rice hull ash raw material into 500 millimole/liter ethanol solution of tetrabutyl titanate, carrying out hydrolysis reaction for 3 minutes at normal temperature after separation, and drying to obtain the silicon dioxide/titanium dioxide composite material.
(2) Adding aluminum powder and chloride salt into the composite material prepared in the step (1), uniformly mixing, heating to 300 ℃ in an inert atmosphere, preserving heat for 9 hours, and cooling to obtain a reactant.
(3) The reaction product was immersed in a sufficient amount of 3mol/l aqueous hydrochloric acid solution and 5 wt% hydrofluoric acid solution in this order to remove impurities, and then separated and dried to obtain an amorphous silicon material.
The chloride salt in the step (2) is aluminum chloride.
The molar ratio of the aluminum powder and the chloride salt in the step (2) to the silicon dioxide in the silicon dioxide raw material in the step (1) is 1.28: 3: 1.
the inert gas in the step (2) is pure argon or a mixed gas of argon (95 v%) and hydrogen (5 v%).
Example 5:
the amorphous silicon material prepared in this embodiment specifically includes the following steps:
(1) uniformly soaking a glass fiber raw material into 800 millimole/liter ethanol solution of tetrabutyl titanate, carrying out hydrolysis reaction for 1 minute at normal temperature after separation, and drying to obtain the silicon dioxide/titanium dioxide composite material.
(2) Adding aluminum powder and chloride salt into the composite material prepared in the step (1), uniformly mixing, heating to 300 ℃ in an inert atmosphere, preserving heat for 6 hours, and cooling to obtain a reactant.
(3) The reaction product was immersed in a sufficient amount of 3mol/l aqueous hydrochloric acid solution and 5 wt% hydrofluoric acid solution in this order to remove impurities, and then separated and dried to obtain an amorphous silicon material.
The chloride salt in the step (2) is a mixture of sodium chloride and aluminum chloride.
The molar ratio of the aluminum powder and the chloride salt in the step (2) to the silicon dioxide in the silicon dioxide raw material in the step (1) is 1.28: 2: 3: 0.68.
the inert gas in the step (2) is pure argon or a mixed gas of argon (95 v%) and hydrogen (5 v%).
Example 6:
the amorphous silicon material prepared in this embodiment specifically includes the following steps:
(1) the glass fiber raw material is evenly immersed into 100 millimole/liter ethanol solution of tetrabutyl titanate after being ball-milled, and after separation, the hydrolysis reaction is carried out for 1 minute at normal temperature, and the silicon dioxide/titanium dioxide composite material is prepared after drying.
(2) Adding aluminum powder and chloride salt into the composite material prepared in the step (1), uniformly mixing, heating to 250 ℃ in an inert atmosphere, keeping the temperature for 12 hours, and cooling to obtain a reactant.
(3) The reaction product was immersed in a sufficient amount of 3mol/l aqueous hydrochloric acid solution and 5 wt% hydrofluoric acid solution in this order to remove impurities, and then separated and dried to obtain an amorphous silicon material.
The chloride salt in the step (2) is aluminum chloride.
The molar ratio of the aluminum powder and the chloride salt in the step (2) to the silicon dioxide in the silicon dioxide raw material in the step (1) is 1.28: 3: 0.68.
the inert gas in the step (2) is pure argon or a mixed gas of argon (95 v%) and hydrogen (5 v%).
Example 7:
the amorphous silicon material prepared in this embodiment specifically includes the following steps:
(1) uniformly soaking a sandy soil raw material into 600 millimoles/liter ethanol solution of tetrabutyl titanate, carrying out hydrolysis reaction for 1 minute at normal temperature after separation, and drying to obtain the silicon dioxide/titanium dioxide composite material.
(2) Adding aluminum powder and chloride salt into the composite material prepared in the step (1), uniformly mixing, heating to 350 ℃ in an inert atmosphere, preserving heat for 3 hours, and cooling to obtain a reactant.
(3) The reaction product was immersed in a sufficient amount of 3mol/l aqueous hydrochloric acid solution and 5 wt% hydrofluoric acid solution in this order to remove impurities, and then separated and dried to obtain an amorphous silicon material.
The chloride salt in the step (2) is a mixture of potassium chloride and aluminum chloride.
The molar ratio of the aluminum powder and the chloride salt in the step (2) to the silicon dioxide in the silicon dioxide raw material in the step (1) is 1.28: 2: 3: 0.5.
the inert gas in the step (2) is pure argon or a mixed gas of argon (95 v%) and hydrogen (5 v%).
Example 8:
the amorphous silicon material prepared in this embodiment specifically includes the following steps:
(1) the glass optical fiber raw material is uniformly immersed into 100 millimole/liter ethanol solution of tetrabutyl titanate after being ball-milled, and after separation, the silica/titanium dioxide composite material is prepared after hydrolysis reaction for 5 minutes at normal temperature and drying.
(2) Adding aluminum powder and chloride salt into the composite material prepared in the step (1), uniformly mixing, heating to 300 ℃ in an inert atmosphere, preserving heat for 3 hours, and cooling to obtain a reactant.
(3) The reaction product was immersed in a sufficient amount of 3mol/l aqueous hydrochloric acid solution and 5 wt% hydrofluoric acid solution in this order to remove impurities, and then separated and dried to obtain an amorphous silicon material.
The chloride salt in the step (2) is a mixture of sodium chloride and aluminum chloride.
The molar ratio of the aluminum powder and the chloride salt in the step (2) to the silicon dioxide in the silicon dioxide raw material in the step (1) is 1.28: 2: 3: 0.5.
the inert gas in the step (2) is pure argon or a mixed gas of argon (95 v%) and hydrogen (5 v%).
The above description is only illustrative of the preferred embodiments of the present invention and should not be taken as limiting the scope of the invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure should be considered as equivalent effective embodiments, and all the changes or modifications should fall within the protection scope of the technical solution of the present invention.
Claims (10)
1. A method for preparing an amorphous silicon material, which is characterized by comprising the following steps: the method comprises the steps of hydrolyzing tetrabutyl titanate coated with a silicon dioxide raw material to form a silicon dioxide/titanium dioxide composite material, reacting the composite material with aluminum powder in chloride to generate a silicon-containing mixture, removing impurities from the mixture through acid washing, and drying to generate the amorphous silicon material.
2. A method of producing an amorphous silicon material as claimed in claim 1, characterised in that: the method specifically comprises the following steps:
(1) uniformly soaking a silicon dioxide raw material into an ethanol solution of tetrabutyl titanate, separating, performing hydrolysis reaction at normal temperature, and drying to obtain a silicon dioxide/titanium dioxide composite material;
(2) adding aluminum powder and chloride salt into the composite material prepared in the step (1), uniformly mixing, heating and reacting in an inert atmosphere, after the reaction is finished, sequentially immersing reaction products into sufficient hydrochloric acid aqueous solution and hydrofluoric acid solution, removing impurities, and then separating and drying to obtain the amorphous silicon material.
3. A method of producing an amorphous silicon material as claimed in claim 2, characterised in that: the silicon dioxide raw material in the step (1) is one or more of nano silicon dioxide ball powder, diatomite, white carbon black, rice hull ash, glass fiber waste, sand, sandy soil and powder of ball-milled glass.
4. A method of producing an amorphous silicon material as claimed in claim 2, characterised in that: the molar concentration of the ethanol solution of tetrabutyl titanate in the step (1) is 100-800 mmol/L.
5. A method of producing an amorphous silicon material as claimed in claim 2, characterised in that: the hydrolysis reaction condition in the step (1) is reaction for 1-5 minutes at normal temperature.
6. A method of producing an amorphous silicon material as claimed in claim 2, characterised in that: the inert atmosphere in the step (2) is pure argon gas or a mixed gas of hydrogen (5 v%) and argon (95 v%).
7. A method of producing an amorphous silicon material as claimed in claim 2, characterised in that: the chloride salt in the step (2) is aluminum chloride or a mixture of the aluminum chloride and other chloride salts.
8. A method of producing an amorphous silicon material as claimed in claim 2, characterised in that: the molar ratio of the aluminum powder and the chloride salt in the step (2) to the silicon dioxide in the silicon dioxide raw material in the step (1) is 1.28: 2: 3: 0.5 to 1.
9. A method of producing an amorphous silicon material as claimed in claim 2, characterised in that: the heating reaction condition in the step (2) is that the reaction temperature is 250-500 ℃, and the reaction is carried out for 3-12 hours at constant temperature.
10. Amorphous silicon material obtainable by a process according to any one of claims 1 to 9.
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