CN114497482B - Silicon-carbon composite material and preparation method thereof - Google Patents
Silicon-carbon composite material and preparation method thereof Download PDFInfo
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- CN114497482B CN114497482B CN202111672279.4A CN202111672279A CN114497482B CN 114497482 B CN114497482 B CN 114497482B CN 202111672279 A CN202111672279 A CN 202111672279A CN 114497482 B CN114497482 B CN 114497482B
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- 239000002153 silicon-carbon composite material Substances 0.000 title claims abstract description 26
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- 239000000243 solution Substances 0.000 claims abstract description 38
- 239000011159 matrix material Substances 0.000 claims abstract description 37
- 239000000843 powder Substances 0.000 claims abstract description 33
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 28
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 27
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 24
- 238000005406 washing Methods 0.000 claims abstract description 21
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 20
- 238000003756 stirring Methods 0.000 claims abstract description 20
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 claims abstract description 17
- 239000002210 silicon-based material Substances 0.000 claims abstract description 17
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims abstract description 14
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 claims abstract description 12
- 229910001428 transition metal ion Inorganic materials 0.000 claims abstract description 12
- 238000001816 cooling Methods 0.000 claims abstract description 11
- 238000001354 calcination Methods 0.000 claims abstract description 7
- 239000011247 coating layer Substances 0.000 claims abstract description 6
- 239000000839 emulsion Substances 0.000 claims abstract description 5
- 239000011248 coating agent Substances 0.000 claims abstract description 4
- 238000000576 coating method Methods 0.000 claims abstract description 4
- 239000011259 mixed solution Substances 0.000 claims abstract description 4
- 238000007740 vapor deposition Methods 0.000 claims abstract description 4
- 238000001035 drying Methods 0.000 claims abstract description 3
- 239000007787 solid Substances 0.000 claims abstract description 3
- 239000008367 deionised water Substances 0.000 claims description 20
- 229910021641 deionized water Inorganic materials 0.000 claims description 20
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 15
- 239000010410 layer Substances 0.000 claims description 14
- XIXADJRWDQXREU-UHFFFAOYSA-M lithium acetate Chemical compound [Li+].CC([O-])=O XIXADJRWDQXREU-UHFFFAOYSA-M 0.000 claims description 8
- 239000010936 titanium Substances 0.000 claims description 8
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 6
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 239000011572 manganese Substances 0.000 claims description 5
- 235000006408 oxalic acid Nutrition 0.000 claims description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 4
- 229910021645 metal ion Inorganic materials 0.000 claims description 4
- 238000000034 method Methods 0.000 claims description 4
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims description 2
- 229910052749 magnesium Inorganic materials 0.000 claims description 2
- 229910052748 manganese Inorganic materials 0.000 claims description 2
- -1 titanium ions Chemical class 0.000 claims description 2
- 229910001437 manganese ion Inorganic materials 0.000 claims 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 10
- 229910052710 silicon Inorganic materials 0.000 abstract description 10
- 239000010703 silicon Substances 0.000 abstract description 10
- 239000002131 composite material Substances 0.000 abstract description 8
- 239000003054 catalyst Substances 0.000 abstract description 6
- 239000000463 material Substances 0.000 abstract description 6
- 239000010405 anode material Substances 0.000 abstract description 5
- 230000009467 reduction Effects 0.000 abstract description 5
- 239000007788 liquid Substances 0.000 abstract description 4
- 238000004140 cleaning Methods 0.000 abstract description 2
- 230000001351 cycling effect Effects 0.000 abstract description 2
- 238000006722 reduction reaction Methods 0.000 abstract description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 12
- 239000010935 stainless steel Substances 0.000 description 12
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- 239000007789 gas Substances 0.000 description 8
- 235000019441 ethanol Nutrition 0.000 description 7
- 239000002244 precipitate Substances 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 4
- 239000005977 Ethylene Substances 0.000 description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 230000002708 enhancing effect Effects 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 238000005303 weighing Methods 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 3
- 239000012300 argon atmosphere Substances 0.000 description 3
- 230000003139 buffering effect Effects 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 229910052744 lithium Inorganic materials 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- 239000005543 nano-size silicon particle Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 238000009830 intercalation Methods 0.000 description 2
- 230000002687 intercalation Effects 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- 229940071125 manganese acetate Drugs 0.000 description 2
- UOGMEBQRZBEZQT-UHFFFAOYSA-L manganese(2+);diacetate Chemical compound [Mn+2].CC([O-])=O.CC([O-])=O UOGMEBQRZBEZQT-UHFFFAOYSA-L 0.000 description 2
- SOQBVABWOPYFQZ-UHFFFAOYSA-N oxygen(2-);titanium(4+) Chemical compound [O-2].[O-2].[Ti+4] SOQBVABWOPYFQZ-UHFFFAOYSA-N 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000012983 electrochemical energy storage Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 229910021426 porous silicon Inorganic materials 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005185 salting out Methods 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000011856 silicon-based particle Substances 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000003786 synthesis reaction 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
- H01M4/362—Composites
-
- 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
-
- 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
- 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
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
-
- 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
- H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
-
- 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 preparation method of the silicon-carbon composite material comprises the following steps: (1) Dissolving tetraethoxysilane, hexadecyl trimethyl ammonium bromide, a catalyst and transition metal ions in an alcohol solution, and stirring to obtain a solution A; (2) preparing an alcohol-water mixed solution B; (3) Adding the solution A into the solution B, stirring to obtain emulsion C, standing and centrifuging to obtain solid matters, cleaning and drying, and calcining at high temperature to obtain powder D; (4) And (3) carrying out high-temperature reduction, cooling and washing on the powder D, and coating carbon by vapor deposition to obtain the silicon-carbon composite material. The silicon-carbon composite material takes a silicon-carbon material as a matrix, the silicon material and the carbon material in the matrix are uniformly distributed, transition metal ions are doped in the matrix, and a carbon coating layer is coated outside the matrix. The invention adopts the liquid silicon source and the liquid carbon source to be fully mixed and then reduced and sintered to obtain the composite anode material with evenly distributed silicon and carbon; meanwhile, transition metal ions are adopted to dope the matrix material, so that the conductivity and the cycling stability of the material are improved.
Description
Technical Field
The invention belongs to the technical field of composite materials, and particularly relates to a silicon-carbon composite material and a preparation method thereof.
Background
Lithium ion batteries are receiving extensive attention as the electrochemical energy storage devices with the most promising application prospect at present. The negative electrode material is an important component in the battery and is one of important materials for improving the performance of the battery. Compared with the graphite anode materials widely used at present, the silicon material has high theoretical capacity (the theoretical capacity can reach4200 mAh/g), about ten times that of carbonaceous material, and has a low lithium intercalation potential (Si average delithiation potential 0.4V vs. Li/Li) + )。
The silicon material can face huge volume change (> 300%) in the process of lithium intercalation, so that Si particles are broken, the structure collapses, and active substances are separated from a current collector, thereby seriously affecting the cycle performance of the battery; in addition, silicon materials have poor conductivity and have large irreversible capacity loss. At present, nano silicon or silicon oxide is mainly adopted for modification, so that the cycle performance of the silicon-based material can be effectively improved. The nano-size design can obviously slow down the material breakage caused by expansion, but the specific surface area is large and aggregation is easy to occur; in addition, carbon materials are often added for the purpose of improving conductivity, but nano-silicon and carbon materials often cannot be uniformly dispersed due to the problems of poor surface affinity and non-uniform size.
Disclosure of Invention
The invention aims to solve the technical problem that nano silicon and carbon materials are difficult to uniformly disperse, overcomes the defects and the shortcomings in the background art, and provides a silicon-carbon composite material and a preparation method thereof.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
the preparation method of the silicon-carbon composite material comprises the following steps:
(1) Dissolving tetraethoxysilane, hexadecyl trimethyl ammonium bromide, a catalyst and transition metal ions in an alcohol solution, and stirring to obtain a solution A;
(2) Preparing an alcohol-water mixed solution B;
(3) Adding the solution A into the solution B, stirring to obtain emulsion C, standing and centrifuging the emulsion C to obtain a solid, cleaning, drying and calcining at high temperature to obtain powder D;
(4) And (3) carrying out high-temperature reduction, cooling and washing on the powder D, and coating carbon by vapor deposition to obtain the silicon-carbon composite material.
CTAB (cetyltrimethylammonium bromide) plays roles of a surfactant and a dispersing agent, and meanwhile, liquid phase synthesis can ensure uniform material dispersion, so that a matrix material with uniformly mixed silicon and carbon is obtained.
Preferably, the molar ratio of ethyl orthosilicate to cetyltrimethylammonium bromide in step (1) is 10:1-1:1, more preferably 8:1-1:1.
Preferably, lithium acetate is added in the step (1), and the molar ratio of the lithium acetate to the tetraethoxysilane is 1:1-1:2. Residual Li of lithium acetate in matrix + The lithium ion battery plays a role in supplementing lithium, and simultaneously assists in uniform dispersion and plays a role in promoting reaction by salting out during dispersion.
Preferably, in the step (1), the catalyst is oxalic acid, the alcohol solution is an absolute alcohol solution, the transition metal ions are manganese and/or titanium, and the transition metal ions can remarkably improve the electronic conductivity of the silicon-based material; in the step (2), the volume ratio of the concentrated ammonia water to the ethanol solution to the deionized water is 1:1:0.5-1:3:5. The doping of metal ions is performed in the solution step, so that the metal ions are dispersed and doped more uniformly.
Preferably, the stirring in the step (3) is carried out at a high speed of 1000-4000rpm for 10min and then at a uniform speed of 500-2000rpm for 1-10h. Preferably, the high temperature reduction in step (4) is specifically: placing the powder D into a container, placing metal Ca or Mg powder on the lower layer, and introducing inert gas for high-temperature reduction at 500-800 ℃.
Preferably, the washing in step (4) is specifically: washing with dilute hydrochloric acid, washing with hydrofluoric acid, and washing with deionized water.
Under the same technical conception, the invention also provides a silicon-carbon composite material, wherein the silicon-carbon composite material takes a silicon-carbon material as a matrix, the silicon material and the carbon material in the carbon-silicon material matrix are uniformly distributed, transition metal ions are doped in the matrix material, and a carbon coating layer is coated outside the matrix.
The matrix carbon plays roles in buffering silicon-based expansion and enhancing electron conductivity, and the surface layer coated carbon plays roles in reducing side reaction of electrolyte and enhancing conductivity among particles. The two carbons cooperate with the buffer of the volume change of the silicon base, and the doping of metal ions stabilizes the silicon base material structure on the one hand and enhances the conductivity on the other hand.
Preferably, the carbon mass ratio in the silicon-carbon material matrix is 1% -30%, the carbon mass ratio in the silicon-carbon composite material is 1% -50%, more preferably 3% -40%, and the transition metal ion mass ratio is 1% -10%, more preferably 2% -6%.
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the invention, the liquid silicon source and the liquid carbon source are fully mixed and then reduced and sintered, so that the composite anode material with evenly distributed silicon and carbon can be obtained; meanwhile, transition metal ions are adopted to dope the matrix material, so that the conductivity and the cycling stability of the material are improved.
(2) The loose porous silicon-based material obtained by metallothermic reduction is beneficial to resisting volume change in the circulation process.
(3) The matrix carbon plays roles in buffering silicon-based expansion and enhancing electron conductivity, the surface layer cladding carbon plays roles in reducing side reaction of electrolyte and enhancing conductivity among particles, and the two carbons cooperate with the volume change of the buffering silicon-based.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is an SEM image of a coated silicon-carbon anode material of example 1;
Detailed Description
The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments are shown, for the purpose of illustrating the invention, but the scope of the invention is not limited to the specific embodiments shown.
Unless defined otherwise, all technical and scientific terms used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the scope of the present invention.
Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or may be prepared by existing methods.
Example 1:
according to the mol ratio of 1:1:0.5, weighing analytically pure lithium acetate, tetraethoxysilane and CTAB, uniformly dispersing into absolute ethyl alcohol, adding a small amount of oxalic acid as a catalyst, and adding manganese acetate with the molar ratio of 0.1 and nano titanium dioxide with the molar ratio of 0.05 to obtain a solution A; uniformly mixing 10mL of concentrated ammonia water, 16mL of ethanol and 25mL of deionized water to obtain a solution B; and (3) rapidly adding the solution A into the solution B, stirring at a high speed of 1000-4000rpm for 10min, stirring at a uniform speed of 500-2000rpm for 2h, standing for 2h, centrifugally separating to obtain a precipitate, washing the precipitate with deionized water for 5 times, calcining the powder in a tubular furnace argon atmosphere at 750 ℃ for 2h, and naturally cooling to obtain powder D. Placing the powder D on the upper layer of a stainless steel double-layer pipe in a glove box, and uniformly placing metal magnesium powder on the lower layer; taking out the stainless steel container, placing the stainless steel container in the middle section of a tubular furnace, introducing argon gas to react for 2 hours at the temperature of 650 ℃, naturally cooling, adding the upper powder into 0.1M dilute hydrochloric acid, stirring for 2 hours, taking out, and washing with deionized water; subsequently, the powder was dried at 50℃after washing with a 0.5wt% HF solution and then with deionized water. And (3) placing the dried powder into a reaction furnace, and introducing ethylene gas with the flow rate of 1:1 with nitrogen to react for 2 hours at 850 ℃ to obtain the coated composite material.
The silicon-carbon composite material takes a silicon-carbon material as a matrix, the silicon material and the carbon material in the carbon-silicon material matrix are uniformly distributed, and Mn is doped in the matrix material 2+ And Ti is 4+ The matrix is coated with a carbon coating layer.
Carbon mass ratio in the silicon-carbon material matrix is 20%, carbon mass ratio in the silicon-carbon composite material is 25%, mn 2+ And Ti is 4+ The mass ratio is 3%.
FIG. 1 is an SEM image of a coated silicon-carbon anode material of example 1; it can be seen that the composite material is overcoated with a carbon coating.
The electrical property test result of the carbon-silicon composite material of example 1 is that the matrix resistivity is 0.04985 Ω cm, the buckling capacity is 1853.3mAh/g, and the capacity retention rate is 93.2% after 200 weeks of the cylindrical battery cycle.
Example 2
Weighing tetraethoxysilane and CTAB with a molar ratio of 1:1, uniformly dispersing the tetraethoxysilane and CTAB into absolute ethyl alcohol, adding a small amount of oxalic acid as a catalyst, and adding nano titanium dioxide with a molar ratio of 0.05 to obtain a solution A; uniformly mixing concentrated ammonia water, ethanol and deionized water according to a volume ratio of 2:3:5 to obtain a solution B; and (3) rapidly adding the solution A into the solution B, stirring at a high speed for 10min, stirring at an average speed for 2h, standing for 2h, centrifuging to obtain a precipitate, washing with deionized water sufficiently, calcining the powder at 750 ℃ for 2h, and naturally cooling to obtain powder D. Placing the powder D on the upper layer of a stainless steel double-layer pipe in a glove box, and uniformly placing metal magnesium powder on the lower layer; taking out the stainless steel container, placing the stainless steel container in the middle section of a tubular furnace, introducing argon gas to react for 2 hours at the temperature of 650 ℃, naturally cooling, adding the upper powder into dilute hydrochloric acid, stirring for 2 hours, taking out, and washing with deionized water; then, the powder is dried at 50 ℃ after being washed by HF solution and deionized water for a plurality of times. And (3) placing the dried powder into a reaction furnace, preserving the heat at 850 ℃, and then introducing ethylene gas to carry out vapor deposition reaction for 2 hours to obtain the coated composite material.
The silicon-carbon composite material takes a silicon-carbon material as a matrix, the silicon material and the carbon material in the carbon-silicon material matrix are uniformly distributed, and Mn is doped in the matrix material 2+ And Ti is 4+ The matrix is coated with a carbon coating layer.
The mass ratio of carbon in the silicon-carbon material matrix is 30%, the mass ratio of carbon in the silicon-carbon composite material is 35%, mn 2+ And Ti is 4+ The mass ratio is 2%.
The electrical property test result of the carbon-silicon composite material of example 2 is that the matrix resistivity is 0.08652 Ω cm, the buckling capacity is 1795.4mAh/g, and the capacity retention rate is 90.6% after 200 weeks of the cylindrical battery cycle.
Example 3
Weighing lithium acetate, ethyl orthosilicate and PVP in a molar ratio of 1:1:0.5, uniformly dispersing the lithium acetate, the ethyl orthosilicate and the PVP into absolute ethyl alcohol, adding a small amount of oxalic acid as a catalyst, and adding 0.1mol of manganese acetate to obtain a solution A; uniformly mixing concentrated ammonia water, ethanol and deionized water according to a volume ratio of 2:3:5 to obtain a solution B; and (3) rapidly adding the solution A into the solution B, stirring at a high speed for 10min, stirring at an average speed for 2h, standing for 2h, centrifuging to obtain a precipitate, washing the precipitate with deionized water, calcining the powder in a tubular furnace argon atmosphere at 750 ℃ for 2h, and naturally cooling to obtain powder D. Placing the powder D on the upper layer of a stainless steel double-layer pipe in a glove box, and uniformly placing metal magnesium powder on the lower layer; taking out the stainless steel container, placing the stainless steel container in the middle section of a tubular furnace, introducing argon gas to react for 2 hours at the temperature of 650 ℃, naturally cooling, adding the upper powder into 0.1M dilute hydrochloric acid, stirring for 2 hours, taking out, and washing with deionized water; subsequently, the powder was dried at 50℃after washing with a 0.5wt% HF solution and then with deionized water. And (3) placing the dried powder into a reaction furnace, and introducing ethylene gas with the flow rate of 1:1 with nitrogen to react for 2 hours at 850 ℃ to obtain the coated composite material.
The silicon-carbon composite material takes a silicon-carbon material as a matrix, the silicon material and the carbon material in the carbon-silicon material matrix are uniformly distributed, and Mn is doped in the matrix material 2+ And Ti is 4+ The matrix is coated with a carbon coating layer.
The electrical performance test result of the carbon-silicon composite material of example 3 is that the matrix resistivity is 0.06742 Ω cm, the buckling capacity is 1834.7mAh/g, and the capacity retention rate after 200 weeks of the cylindrical battery is 92.5%.
Comparative example 1
Weighing tetraethoxysilane and CTAB with a molar ratio of 1:0.5, and uniformly dispersing the tetraethoxysilane and CTAB into absolute ethyl alcohol to obtain a solution A; uniformly mixing concentrated ammonia water, ethanol and deionized water according to a volume ratio of 2:3:5 to obtain a solution B; and (3) rapidly adding the solution A into the solution B, stirring at a high speed for 10min, stirring at an average speed for 2h, standing for 2h, centrifuging to obtain a precipitate, washing the precipitate with deionized water, calcining the powder in a tubular furnace argon atmosphere at 750 ℃ for 2h, and naturally cooling to obtain powder D. Placing the powder D on the upper layer of a stainless steel double-layer pipe in a glove box, and uniformly placing metal magnesium powder on the lower layer; taking out the stainless steel container, placing the stainless steel container in the middle section of a tubular furnace, introducing argon gas to react for 2 hours at the temperature of 650 ℃, naturally cooling, adding the upper powder into 0.1M dilute hydrochloric acid, stirring for 2 hours, taking out, and washing with deionized water; subsequently, the powder was dried at 50℃after washing with a 0.5wt% HF solution and then with deionized water. And (3) placing the dried powder into a reaction furnace, and introducing ethylene gas with the flow rate of 1:1 with nitrogen to react for 2 hours at 850 ℃ to obtain the coated composite material.
Table 1: examples 1-3 and comparative examples electrochemical performance test data
Claims (3)
1. The preparation method of the silicon-carbon composite material is characterized by comprising the following steps of:
(1) Dissolving tetraethoxysilane, hexadecyl trimethyl ammonium bromide, oxalic acid, manganese and/or titanium metal ions and lithium acetate in an absolute ethanol solution, and stirring to obtain a solution A; the mol ratio of the tetraethoxysilane to the hexadecyl trimethyl ammonium bromide is 10:1-1:1; the molar ratio of the lithium acetate to the ethyl orthosilicate is 1:1-1:2;
(2) Preparing an alcohol-water mixed solution B, wherein the alcohol-water mixed solution is concentrated ammonia water, an ethanol solution and deionized water, and the volume ratio is 1:1:0.5-1:3:5;
(3) Adding the solution A into the solution B, stirring at a high speed of 1000-4000rpm for 10min, stirring at a uniform speed of 500-2000rpm for 1-10h to obtain emulsion C, standing and centrifuging the emulsion C to obtain a solid, washing, drying and calcining at a high temperature to obtain powder D;
(4) Placing the powder D in a container, placing metal Ca or Mg powder on the lower layer, introducing inert gas, reducing at 500-800 ℃ at high temperature, cooling, washing with dilute hydrochloric acid, washing with hydrofluoric acid, washing with deionized water, and coating carbon by a vapor deposition method to obtain the silicon-carbon composite material.
2. The silicon-carbon composite material prepared by the preparation method of claim 1, wherein the silicon-carbon composite material uses a silicon-carbon material as a matrix, the silicon material and the carbon material in the carbon-silicon material matrix are uniformly distributed, transition metal ions are doped in the matrix, the transition metal ions are manganese ions and titanium ions, and a carbon coating layer is coated outside the matrix.
3. The silicon-carbon composite material according to claim 2, wherein the silicon-carbon material matrix has a carbon mass ratio of 1% to 30%, the silicon-carbon composite material has a carbon mass ratio of 1% to 50%, and the transition metal ion has a mass ratio of 1% to 10%.
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