CN117117162A - Silicon-carbon composite material and preparation method thereof - Google Patents
Silicon-carbon composite material and preparation method thereof Download PDFInfo
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- CN117117162A CN117117162A CN202311004224.5A CN202311004224A CN117117162A CN 117117162 A CN117117162 A CN 117117162A CN 202311004224 A CN202311004224 A CN 202311004224A CN 117117162 A CN117117162 A CN 117117162A
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- isopropanol
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- 239000002153 silicon-carbon composite material Substances 0.000 title claims abstract description 56
- 238000002360 preparation method Methods 0.000 title claims abstract description 23
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims abstract description 47
- 239000000243 solution Substances 0.000 claims abstract description 39
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 38
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims abstract description 38
- 239000005543 nano-size silicon particle Substances 0.000 claims abstract description 36
- 238000001354 calcination Methods 0.000 claims abstract description 29
- 239000003921 oil Substances 0.000 claims abstract description 26
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 20
- GLDOVTGHNKAZLK-UHFFFAOYSA-N octadecan-1-ol Chemical compound CCCCCCCCCCCCCCCCCCO GLDOVTGHNKAZLK-UHFFFAOYSA-N 0.000 claims abstract description 20
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 18
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 18
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 16
- XIYNYTJFQCFZQC-UHFFFAOYSA-N C(C)(C)O.[Si](=O)=O Chemical compound C(C)(C)O.[Si](=O)=O XIYNYTJFQCFZQC-UHFFFAOYSA-N 0.000 claims abstract description 15
- 239000000571 coke Substances 0.000 claims abstract description 14
- 238000010438 heat treatment Methods 0.000 claims abstract description 14
- 239000012298 atmosphere Substances 0.000 claims abstract description 13
- 239000008367 deionised water Substances 0.000 claims abstract description 12
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 12
- 150000004945 aromatic hydrocarbons Chemical class 0.000 claims abstract description 11
- 238000003763 carbonization Methods 0.000 claims abstract description 10
- 238000000227 grinding Methods 0.000 claims abstract description 7
- 239000011261 inert gas Substances 0.000 claims abstract description 7
- 239000011259 mixed solution Substances 0.000 claims abstract description 6
- 239000002994 raw material Substances 0.000 claims abstract description 6
- 239000007787 solid Substances 0.000 claims abstract description 6
- 238000006555 catalytic reaction Methods 0.000 claims abstract description 4
- 238000010025 steaming Methods 0.000 claims abstract description 3
- 239000000126 substance Substances 0.000 claims abstract description 3
- 238000000034 method Methods 0.000 claims description 28
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 17
- 238000003756 stirring Methods 0.000 claims description 17
- 230000008569 process Effects 0.000 claims description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 9
- 238000006243 chemical reaction Methods 0.000 claims description 9
- 238000001704 evaporation Methods 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 7
- 239000006228 supernatant Substances 0.000 claims description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 6
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 5
- 239000005977 Ethylene Substances 0.000 claims description 5
- 238000004523 catalytic cracking Methods 0.000 claims description 5
- 239000002002 slurry Substances 0.000 claims description 5
- 230000035484 reaction time Effects 0.000 claims description 4
- 229910052786 argon Inorganic materials 0.000 claims description 3
- 239000000084 colloidal system Substances 0.000 claims description 3
- 230000000630 rising effect Effects 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 230000001174 ascending effect Effects 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 13
- 229910052710 silicon Inorganic materials 0.000 description 12
- 239000010703 silicon Substances 0.000 description 12
- 239000002010 green coke Substances 0.000 description 8
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 7
- 230000007062 hydrolysis Effects 0.000 description 7
- 238000006460 hydrolysis reaction Methods 0.000 description 7
- 229910001416 lithium ion Inorganic materials 0.000 description 7
- GOQYKNQRPGWPLP-UHFFFAOYSA-N n-heptadecyl alcohol Natural products CCCCCCCCCCCCCCCCCO GOQYKNQRPGWPLP-UHFFFAOYSA-N 0.000 description 6
- 239000012299 nitrogen atmosphere Substances 0.000 description 6
- 238000005406 washing Methods 0.000 description 6
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 5
- 239000003575 carbonaceous material Substances 0.000 description 5
- 229910001873 dinitrogen Inorganic materials 0.000 description 5
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 4
- 239000002202 Polyethylene glycol Substances 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229920001223 polyethylene glycol Polymers 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 239000010406 cathode material Substances 0.000 description 3
- 239000002096 quantum dot Substances 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
- 125000003118 aryl group Chemical group 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000007334 copolymerization reaction Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 238000009831 deintercalation Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000009713 electroplating Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 229910001385 heavy metal Inorganic materials 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 238000009830 intercalation Methods 0.000 description 2
- 230000002687 intercalation Effects 0.000 description 2
- 150000002596 lactones Chemical class 0.000 description 2
- 239000003446 ligand Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 239000005011 phenolic resin Substances 0.000 description 2
- 229920001568 phenolic resin Polymers 0.000 description 2
- 238000006068 polycondensation reaction Methods 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 239000002210 silicon-based material Substances 0.000 description 2
- 229920000428 triblock copolymer Polymers 0.000 description 2
- 102000020897 Formins Human genes 0.000 description 1
- 108091022623 Formins Proteins 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000003837 high-temperature calcination Methods 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 229910021471 metal-silicon alloy Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000007709 nanocrystallization Methods 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000004528 spin coating Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000002604 ultrasonography Methods 0.000 description 1
- 238000001291 vacuum drying Methods 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/386—Silicon or alloys based on silicon
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/134—Electrodes based on metals, Si or alloys
-
- 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
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
Abstract
The application provides a preparation method of a silicon-carbon composite material, which is characterized by comprising the following steps: (1) Dissolving ethyl silicate in a mixed solution of absolute ethyl alcohol and deionized water, generating nano silicon dioxide sol through ammonia water catalysis, centrifuging, adjusting pH, and oscillating and dispersing the obtained solid substance in isopropanol to generate nano silicon dioxide isopropanol solution for later use; (2) Adding the nano silicon dioxide isopropanol sol obtained in the step (1) into a mixed solution of octadecanol and aromatic hydrocarbon-rich oil, heating and steaming to remove isopropanol to obtain a pre-solution, and then carrying out co-carbonization under inert atmosphere to obtain raw coke for later use; (3) And (3) grinding the raw coke obtained in the step (2), and then heating and calcining the ground raw coke in an inert gas atmosphere to obtain the silicon-carbon composite material. Compared with the prior art, the application has the advantages of wide raw material source and low cost; the preparation method is simple, the production efficiency is high, the calcination yield is high, and the electrochemical performance is excellent.
Description
Technical Field
The application relates to the technical field of lithium ion anode material preparation, in particular to a silicon-carbon composite material and a preparation method thereof.
Background
Commercial lithium ion batteries are widely used in the fields of electric automobiles, hybrid electric automobiles, mobile phones, portable electronic devices and the like. Graphite is used as a cathode material of a commercial lithium ion battery, the theoretical specific capacity is 372mAh g < -1 >, and the increasing demands of people on the lithium ion battery with high energy density and high power density cannot be met. The silicon element is the second largest element in the crust, and is next to the oxygen element, so that the resources are rich. In addition, silicon has the advantages of lower lithium intercalation and deintercalation potential, high theoretical specific capacity (4200 mAh.g < -1 >) and the like, and is expected to become a new-generation commercial lithium ion battery cathode material. However, silicon has a huge volume effect (> 300%) in the cycling process, which causes pulverization of a matrix material, so that the cycling performance of the battery is poor, and the commercialization process of the silicon-based anode material is hindered. The main methods for solving the problems are nanocrystallization of silicon, silicon-metal alloy, silicon-metal oxide composite and preparation of silicon-carbon composite materials.
The carbon material has the advantages of small volume change, good ion conductivity and electron conductivity, stable SEI film formation, certain capacity and the like in the process of lithium ion intercalation and deintercalation, and the silicon and the carbon material are compounded to effectively relieve the volume effect of the silicon, so that the carbon material is one of the hot research at present. However, the carbon material has the problem of not tightly combining with silicon when used as a buffer matrix for relieving the volume expansion of silicon, and the electrochemical performance of the battery is rapidly attenuated due to silicon-carbon separation after multiple cycles. It is an important point of research to find a carbon material that can be tightly bonded to silicon, thereby effectively relieving the volume expansion of silicon. To address such issues, researchers in the field have had little success.
The application patent of a silicon-carbon composite material and a preparation method thereof, which are applied by the university of south China, 4 months and 25 days in 2018, has the application publication number CN 108598420A, and the preparation method comprises the following steps: uniformly dispersing nano silicon, a carbon source and quantum dots respectively by using a solvent through ultrasonic, adding a nano silicon solution and a carbon source solution into the quantum dot solution, carrying out ultrasonic mixing, evaporating the solvent to obtain slurry with the solid content of 90% -97%, and carrying out vacuum drying. Grinding the obtained solid, and heating and calcining the solid in an inert gas atmosphere to obtain the silicon-carbon composite material. The preparation method requires quantum dot solution as a material, ultrasound and vacuum as preparation process conditions, and has the advantages of high preparation cost, complex process and lower yield.
Another example is an application patent of a preparation method of a silicon-carbon composite material applied by university of Zhejiang industry, 6.6.month and 18.year 2019, with application publication number CN 109904429A, the preparation method comprises: dissolving ethyl silicate in petroleum ether to form oily solution, adding polyethylene glycol/polyethylene lactone/polyethylene glycol triblock copolymer into the oily solution, stirring to react to obtain pre-solution, adding oil-soluble phenolic resin, stirring with water to form turbid liquid, spin-coating on the surface of a glass substrate, pre-drying, and calcining in protective atmosphere to obtain the powdery silicon-carbon composite material. The hydrolysis speed of the ethyl silicate is low, and the reaction is carried out only by directly stirring and mixing the ethyl silicate, the petroleum ether, the polyethylene glycol/polyethylene lactone/polyethylene glycol triblock copolymer and the oil-soluble phenolic resin, so that the production efficiency of the whole process is low.
Aiming at the technical problems faced by the current lithium ion battery cathode material, the scheme is to be improved from objective factors such as process cost, process conditions and the like.
Disclosure of Invention
The application provides a silicon-carbon composite material and a preparation method thereof, which aim to realize the purpose of preparing a silicon-carbon composite material with uniform carbon-silicon distribution at low cost, ensure that the prepared silicon-carbon composite material has excellent electrochemical performance on the basis, and ensure high production efficiency in the preparation process.
In order to achieve the above object, the present application provides a method for preparing a silicon carbon composite material, which is characterized by comprising the steps of:
(1) Dissolving ethyl silicate in a mixed solution of absolute ethyl alcohol and deionized water, generating nano silicon dioxide sol through ammonia water catalysis, centrifuging, adjusting pH, and oscillating and dispersing the obtained solid substance in isopropanol to generate nano silicon dioxide isopropanol solution for later use;
(2) Adding the nano silicon dioxide isopropanol sol obtained in the step (1) into a mixed solution of octadecanol and aromatic hydrocarbon-rich oil, heating and steaming to remove isopropanol to obtain a pre-solution, and then carrying out co-carbonization under inert atmosphere to obtain raw coke for later use;
(3) And (3) grinding the raw coke obtained in the step (2), and then heating and calcining the ground raw coke in an inert gas atmosphere to obtain the silicon-carbon composite material.
Preferably, in step (1), the method for preparing the nano silica sol comprises the steps of:
a. adding ethyl silicate twice, adding ethyl silicate for the first time, mixing with ammonia water, deionized water and absolute ethyl alcohol, and stirring for the first time;
b. and adding ethyl silicate for the second time, and stirring for the second time to obtain the nano silicon dioxide sol.
Preferably, the volume ratio of deionized water, ammonia water and ethyl silicate is 1: 1-2: 2-3, wherein the volume ratio of the ethyl silicate added for the first time to the ethyl silicate added for the second time is 3:2, the ammonia water is concentrated ammonia water.
If the concentration of the ethyl silicate is too low, the silicon content in the prepared silicon-carbon composite material is too low, the performance is poor, and if the concentration is too high, a large amount of hydrolysis of the ethyl silicate in water drops and the damage of an assembled particle structure can be caused, so that the preparation cannot be realized. In this concentration range, smooth preparation of the silicon-carbon composite material having good properties can be ensured.
The reaction rate of the ethyl silicate is slow when the ethyl silicate reacts with other compounds, so the ethyl silicate is added in two times to completely react.
Preferably, the reaction temperature of the first stirring and the second stirring is 30-40 ℃ and the reaction time is 3h; the centrifugal rotating speed is 8000r/min, and the centrifugal time is 5min; the pH regulating method includes centrifuging nanometer silica colloid, washing with absolute alcohol for several times, and centrifuging until the supernatant liquid has pH of 6-8.
The pH is adjusted by taking absolute ethyl alcohol as a solvent, and the absolute ethyl alcohol is taken as a preparation raw material of the application, so that the generation of new impurities can be avoided, the concentrated ammonia water can be neutralized, and the industrial wastewater is prevented from being polluted.
Preferably, in step (2), the mass ratio of stearyl alcohol to the aromatic-rich oil is 1: 4-5, the mass ratio of the nano silicon dioxide to the aromatic hydrocarbon-rich oil is 1: 80-120; the heating and evaporating process is that the oil bath is evaporated until no white fog is emitted, and the rising temperature in the heating process is 5 ℃ min < -1 >; the reaction pressure of the co-carbonization is 0.1-1 MPa, the reaction temperature is 400-500 ℃, and the reaction time is 2-10 h.
The evaporation efficiency can be improved by the oil bath evaporation, and the preparation process time is shortened.
Preferably, the aromatic-rich oil is one or more of ethylene tar, catalytic cracking slurry oil or vacuum residuum.
Preferably, in the step (3), the inert gas is nitrogen or argon, the heating process is carried out at the rising temperature of 1-10 ℃ for min < -1 >, the calcining temperature is 1200-1600 ℃, and the calcining time is 0.5-6 h.
The inert gas does not participate in the chemical reaction, so that the oxidation reaction can be effectively prevented; the nitrogen atmosphere has fast heat transfer, the high-temperature calcination can increase the conductivity on one hand, and in addition, the calcination can also generate defect sites, so that the catalytic activity is improved; the argon has low coefficient of heat conductivity, can be applied to extremely high temperature, can reduce the generation of impurities and improve the purity of products.
On the other hand, the application also provides a silicon-carbon composite material which is prepared by the method provided by the application.
On the other hand, the application also provides a battery cathode which takes the silicon-carbon composite material provided by the application as a raw material.
On the other hand, the application also provides a battery, which comprises the battery cathode provided by the application.
The beneficial effects of the application are as follows:
the ethyl silicate has no binding force and can be used only after hydrolysis, and the hydrolysis of the ethyl silicate is carried out slowly under the condition of only water.
The ligand exchange technology is utilized to realize the uniform dispersion of nano silicon dioxide in the aromatic hydrocarbon-rich oil, and the controllable copolymerization and in-situ carbonization-reduction coupling reaction with nano silicon in the thermal polycondensation process of the aromatic hydrocarbon-rich oil is realized.
The prepared silicon-carbon composite material can relieve the problems of volume expansion and the like of a silicon-based material in the battery cycle process, and a battery prepared from the silicon-carbon composite material has excellent electrochemical performance.
The application has wide raw material sources and low cost; the preparation method is simple, the production efficiency is high, the calcination yield is high, electroplating and heavy metal are not needed, and the silicon carbon of the prepared silicon-carbon composite material is uniformly distributed.
Drawings
FIG. 1 is an X-ray diffraction (XRD) pattern for the silicon carbon composites of examples 1-5, where 1200 is the calcination temperature of example 4, 1300 is the calcination temperature of example 5, 1400 is the calcination temperature of example 2, 1500 is the calcination temperature of example 3, 1600 is the calcination temperature of example 1, and intensity is the intensity.
Fig. 2 is a Transmission Electron Microscope (TEM) image of the silicon carbon composite material in example 1 of the present application.
Fig. 3 is a Transmission Electron Microscope (TEM) image of the silicon carbon composite material in example 4 of the present application.
Fig. 4 is a Scanning Electron Microscope (SEM) image of the silicon carbon composite material of example 1 of the present application.
Fig. 5 is a Scanning Electron Microscope (SEM) image of the silicon carbon composite in example 2 of the present application.
Figure 6 is a Scanning Electron Microscope (SEM) image of a silicon carbon composite in example 3 of the present application.
Fig. 7 is a Scanning Electron Microscope (SEM) image of a silicon carbon composite material in example 4 of the present application.
Figure 8 is a Scanning Electron Microscope (SEM) image of a silicon carbon composite in example 5 of the present application.
Fig. 9 is a Scanning Electron Microscope (SEM) image of nano-silica in example 1 of the present application.
Detailed Description
The following description of the technical solutions of several embodiments of the present application will be made clearly and completely with reference to the accompanying drawings of several embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to fall within the scope of the application.
In the description of the present application, the terms "left", "right", "middle", "front" and "rear", etc. refer to the orientation or positional relationship based on that shown in the drawings, for convenience of description of the present application only, and do not require that the present application must be constructed and operated in a specific orientation, and thus should not be construed as limiting the present application.
In the description of the present application, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Referring to fig. 1-9, fig. 1 is an X-ray diffraction (XRD) pattern of the silicon-carbon composite material of examples 1-5, wherein 1200 is the calcination temperature of example 4, 1300 is the calcination temperature of example 5, 1400 is the calcination temperature of example 2, 1500 is the calcination temperature of example 3, 1600 is the calcination temperature of example 1, and intensity is the intensity; FIG. 2 is a Transmission Electron Microscope (TEM) image of a silicon-carbon composite of example 1 of the present application; FIG. 3 is a Transmission Electron Microscope (TEM) image of a silicon-carbon composite according to example 4 of the present application; fig. 4 is a Scanning Electron Microscope (SEM) image of the silicon carbon composite of example 1 of the present application; fig. 5 is a Scanning Electron Microscope (SEM) image of the silicon carbon composite of example 2 of the present application; figure 6 is a Scanning Electron Microscope (SEM) image of a silicon carbon composite in example 3 of the present application; fig. 7 is a Scanning Electron Microscope (SEM) image of a silicon carbon composite material according to example 4 of the present application; figure 8 is a Scanning Electron Microscope (SEM) image of a silicon carbon composite of example 5 of the present application; fig. 9 is a Scanning Electron Microscope (SEM) image of nano-silica in example 1 of the present application.
Example 1
(1) 1.5mL of ethyl silicate, 1.7mL of concentrated ammonia water, 1mL of deionized water and 50mL of absolute ethyl alcohol are mixed in a 100mL round bottom flask, stirred for 3h at 40 ℃, then 1mL of ethyl silicate is added, and stirring is continued for 3h at 40 ℃ to obtain nano silica sol.
(2) Centrifuging the nano silica sol of the step (1) by using a 8000r & min & lt-1 & gt centrifuge, and washing and centrifuging the nano silica sol for multiple times by using absolute ethyl alcohol until the pH value of the supernatant fluid of the centrifuge is 6. Then dissolving in 25mL of isopropanol to obtain nano silicon dioxide isopropanol solution, and taking 0.1763g of nano silicon dioxide-containing solution for later use.
(3) Uniformly mixing 21.16g of ethylene tar and 7g of stearyl alcohol, adding the nano silicon dioxide isopropanol solution obtained in the step (2), and evaporating most isopropanol in an oil bath at 100 ℃ until no white fog appears, thus obtaining a pre-solution containing a small amount of isopropanol.
(4) Adding the pre-solution obtained in the step (3) into a co-carbonization kettle, and reacting for 5 hours under the atmosphere of nitrogen gas, wherein the temperature in the kettle is kept at 450 ℃, the pressure is 0.6MPa, so as to obtain 2.581g of raw coke.
(5) After grinding and crushing the green coke obtained in the step (4), 2.581g of the green coke is put into a nitrogen atmosphere and calcined at 1600 ℃ for 6 hours to obtain 1.6g of the silicon-carbon composite material of the example 1, wherein the calcination yield is 61.99%.
Example 2
(1) 1.8mL of ethyl silicate, 2mL of concentrated ammonia water, 1mL of deionized water and 50mL of absolute ethyl alcohol are mixed in a 100mL round bottom flask, stirred for 3h at 30 ℃, then 1.2mL of ethyl silicate is added, and stirring is continued for 3h at 30 ℃ to obtain nano silica sol.
(2) Centrifuging the nano silica sol of the step (1) by using a 8000r & min & lt-1 & gt centrifuge, and washing and centrifuging the nano silica sol with absolute ethyl alcohol for multiple times until the pH value of the supernatant liquid of the centrifuge is 7. Then dissolving in 25mL of isopropanol to obtain nano silicon dioxide isopropanol solution, and taking 0.4210g of nano silicon dioxide-containing solution for later use.
(3) 33.68g of catalytic cracking oil and 6.74g of stearyl alcohol are uniformly mixed, then the nano silicon dioxide isopropanol solution obtained in the step (2) is added, and most isopropanol is evaporated in an oil bath at the temperature of 100 ℃ until no white fog emerges, so that a pre-solution containing a small amount of isopropanol is obtained.
(4) Adding the pre-solution obtained in the step (3) into a co-carbonization kettle, and reacting for 5 hours under the atmosphere of nitrogen gas, wherein the temperature in the kettle is kept at 400 ℃, the pressure is 0.4MPa, so as to obtain 5.327g of raw coke.
(5) After the green coke obtained in (4) was ground and pulverized, 3.688g of the green coke was put into a nitrogen atmosphere and calcined at 1400℃for 5 hours to obtain 2.61g of the silicon-carbon composite material of example 2, with a calcination yield of 70.72%.
Example 3
(1) 1.2mL of ethyl silicate, 1mL of concentrated ammonia water, 1mL of deionized water and 50mL of absolute ethyl alcohol are mixed, stirred in a 100mL round bottom flask at 40 ℃ for 3h, then 0.8mL of ethyl silicate is added, and stirring is continued for 3h at 40 ℃ to obtain nano silica sol.
(2) Centrifuging the nano silica sol in the step (1) by using a 8000r & min & lt-1 & gt centrifuge, and washing and centrifuging the nano silica sol with absolute ethyl alcohol for multiple times until the pH value of the supernatant liquid of the centrifuge is 8. Then dissolving in 25mL of isopropanol to obtain nano silicon dioxide isopropanol solution, and taking 0.2546g of nano silicon dioxide-containing solution for later use.
(3) Uniformly mixing 30g of vacuum residue and 6g of stearyl alcohol, adding all the nano silicon dioxide isopropanol solution obtained in the step (2), and evaporating most isopropanol in an oil bath at 100 ℃ until no white fog appears, thus obtaining a pre-solution containing a small amount of isopropanol.
(4) And (3) adding the pre-solution obtained in the step (3) into a co-carbonization kettle, and reacting for 5 hours under the atmosphere of nitrogen gas, wherein the temperature in the kettle is kept at 430 ℃, the pressure is 0.8MPa, so as to obtain 6.046g of raw coke.
(5) After the green coke obtained in (4) was ground and pulverized, 3.063g of the green coke was put into a nitrogen atmosphere and calcined at 1500℃for 5 hours to obtain 2.22g of the silicon-carbon composite material of example 3, with a calcination yield of 72.58%.
Example 4
(1) 1.8mL of ethyl silicate, 1mL of concentrated ammonia water, 1mL of deionized water and 50mL of absolute ethyl alcohol are mixed, stirred in a 100mL round bottom flask at 40 ℃ for 3h, then 1.2mL of ethyl silicate is added, and stirring is continued for 3h at 40 ℃ to obtain nano silica sol.
(2) Centrifuging the nano silica sol of the step (1) by using a 8000r & min & lt-1 & gt centrifuge, and washing and centrifuging the nano silica sol with absolute ethyl alcohol for multiple times until the pH value of the supernatant liquid of the centrifuge is 6. Then dissolving in 25mL of isopropanol to obtain nano silicon dioxide isopropanol solution, and taking 0.2783g of nano silicon dioxide-containing solution for later use.
(3) Uniformly mixing 10g of ethylene tar, 20g of catalytic cracking slurry oil and 6g of stearyl alcohol, adding all the nano silicon dioxide isopropyl alcohol solution obtained in the step (2), and evaporating most of isopropyl alcohol in an oil bath at the temperature of 100 ℃ until no white fog appears, thus obtaining a pre-solution containing a small amount of isopropyl alcohol.
(4) Adding the pre-solution obtained in the step (3) into a co-carbonization kettle, and reacting for 5 hours under the atmosphere of nitrogen gas, wherein the temperature in the kettle is kept at 430 ℃, the pressure is 0.8MPa, so as to obtain 5.614g of raw coke.
(5) Grinding and crushing the green coke obtained in the step (4), taking 2.344g, placing the mixture into a nitrogen atmosphere, and calcining the mixture at 1200 ℃ for 6 hours to obtain 1.640g of the silicon-carbon composite material of the example 4, wherein the calcination yield is 69.88%.
Example 5
(1) 1.8mL of ethyl silicate, 1mL of concentrated ammonia water, 1mL of deionized water and 50mL of absolute ethyl alcohol are mixed, stirred in a 100mL round bottom flask at 40 ℃ for 3h, then 1.2mL of ethyl silicate is added, and stirring is continued for 3h at 40 ℃ to obtain nano silica sol.
(2) Centrifuging the nano silica sol of the step (1) by using a 8000r & min & lt-1 & gt centrifuge, and washing and centrifuging the nano silica sol with absolute ethyl alcohol for multiple times until the pH value of the supernatant liquid of the centrifuge is 7. Then dissolving in 25mL of isopropanol to obtain nano silicon dioxide isopropanol solution, and taking 0.2659g of nano silicon dioxide-containing solution for later use.
(3) Uniformly mixing 10g of ethylene tar, 10g of catalytic cracking slurry oil, 10g of vacuum residuum and 6g of stearyl alcohol, adding all of the nano silicon dioxide isopropanol solution obtained in the step (2), and evaporating most isopropanol in an oil bath at 100 ℃ until no white fog emerges, thus obtaining a pre-solution containing a small amount of isopropanol.
(4) Adding the pre-solution obtained in the step (3) into a co-carbonization kettle, and reacting for 5 hours under the atmosphere of nitrogen gas, wherein the temperature in the kettle is kept at 430 ℃, the pressure is 0.8MPa, so as to obtain 5.352g of raw coke.
(5) Grinding and crushing the green coke obtained in the step (4), taking 2.474g, and placing the mixture into a nitrogen atmosphere to calcine the mixture for 2 hours at 1300 ℃ to obtain 1.490g of the silicon-carbon composite material of the example 5, wherein the calcination yield is 60.27%.
In summary, in the application, because the ethyl silicate has no binding force, the ethyl silicate can be used only after hydrolysis, the hydrolysis of the ethyl silicate is very slow under the condition of only water, and the hydrolysis speed is greatly accelerated by utilizing the method of ammonia water catalysis and heating stirring.
The ligand exchange technology is utilized to realize the uniform dispersion of nano silicon dioxide in the aromatic hydrocarbon-rich oil, and the controllable copolymerization and in-situ carbonization-reduction coupling reaction with nano silicon in the thermal polycondensation process of the aromatic hydrocarbon-rich oil is realized.
The prepared silicon-carbon composite material can relieve the problems of volume expansion and the like of a silicon-based material in the battery cycle process, and a battery prepared from the silicon-carbon composite material has excellent electrochemical performance.
The application has wide raw material sources and low cost; the preparation method is simple, the production efficiency is high, the calcination yield is high, electroplating and heavy metal are not needed, and the silicon carbon of the prepared silicon-carbon composite material is uniformly distributed.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The preparation method of the silicon-carbon composite material is characterized by comprising the following steps of:
(1) Dissolving ethyl silicate in a mixed solution of absolute ethyl alcohol and deionized water, generating nano silicon dioxide sol through ammonia water catalysis, centrifuging, adjusting pH, and oscillating and dispersing the obtained solid substance in isopropanol to generate nano silicon dioxide isopropanol solution for later use;
(2) Adding the nano silicon dioxide isopropanol sol obtained in the step (1) into a mixed solution of octadecanol and aromatic hydrocarbon-rich oil, heating and steaming to remove isopropanol to obtain a pre-solution, and then performing co-carbonization under inert atmosphere to obtain raw coke for later use;
(3) And (3) grinding the raw coke in the step (2), and then heating and calcining the ground raw coke in an inert gas atmosphere to obtain the silicon-carbon composite material.
2. The method for preparing a silicon-carbon composite material according to claim 1, wherein in the step (1), the method for preparing the nano silica sol comprises the following steps:
a. adding the ethyl silicate twice, adding the ethyl silicate for the first time, mixing with the ammonia water, the deionized water and the absolute ethyl alcohol, and stirring for the first time;
b. and adding the ethyl silicate for the second time, and stirring for the second time to obtain the nano silicon dioxide sol.
3. The method for preparing a silicon-carbon composite material according to claim 2, wherein the volume ratio of deionized water, ammonia water and ethyl silicate is 1: 1-2: 2-3, wherein the volume ratio of the ethyl silicate added for the first time to the ethyl silicate added for the second time is 3:2, the ammonia water is concentrated ammonia water.
4. The method for preparing a silicon-carbon composite material according to claim 3, wherein the reaction temperature of the first stirring and the second stirring is 30-40 ℃ and the reaction time is 3h; the centrifugal rotating speed is 8000r/min, and the centrifugal time is 5min; the pH adjusting method is to centrifuge out nano silicon dioxide colloid, and wash and centrifuge the nano silicon dioxide colloid with absolute ethyl alcohol for a plurality of times until the pH of supernatant liquid of the centrifuge is between 6 and 8.
5. The method for preparing a silicon-carbon composite material according to claim 1, wherein in the step (2), the mass ratio of the octadecanol to the arene-rich oil is 1: 4-5, wherein the mass ratio of the nano silicon dioxide to the aromatic hydrocarbon-rich oil is 1: 80-120; the heating and evaporating process is that oil bath is evaporated until no white fog is emitted, and the rising temperature in the heating process is 5 ℃ min < -1 >; the reaction pressure of the co-carbonization is 0.1-1 MPa, the reaction temperature is 400-500 ℃, and the reaction time is 2-10 h.
6. The method for preparing a silicon-carbon composite material according to claim 5, wherein the aromatic hydrocarbon-rich oil is one or more of ethylene tar, catalytic cracking slurry oil or vacuum residue.
7. The method for preparing a silicon-carbon composite material according to claim 1, wherein in the step (3), the inert gas is nitrogen or argon, the heating process is carried out at an ascending temperature of 1-10 ℃ min < -1 >, the calcining temperature is 1200-1600 ℃, and the calcining time is 0.5-6 h.
8. A silicon carbon composite material prepared by the method of any one of claims 1 to 7.
9. A battery cathode, characterized in that the silicon-carbon composite material of claim 8 is used as a raw material.
10. A battery comprising the battery anode of claim 9.
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