CN114497482A - Silicon-carbon composite material and preparation method thereof - Google Patents
Silicon-carbon composite material and preparation method thereof Download PDFInfo
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- CN114497482A CN114497482A CN202111672279.4A CN202111672279A CN114497482A CN 114497482 A CN114497482 A CN 114497482A CN 202111672279 A CN202111672279 A CN 202111672279A CN 114497482 A CN114497482 A CN 114497482A
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- 239000002153 silicon-carbon composite material Substances 0.000 title claims abstract description 32
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- 239000000243 solution Substances 0.000 claims abstract description 40
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 30
- 239000011159 matrix material Substances 0.000 claims abstract description 30
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 29
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000000843 powder Substances 0.000 claims abstract description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 23
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 20
- 238000005406 washing Methods 0.000 claims abstract description 20
- 238000003756 stirring Methods 0.000 claims abstract description 19
- 239000002210 silicon-based material Substances 0.000 claims abstract description 17
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910001428 transition metal ion Inorganic materials 0.000 claims abstract description 14
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims abstract description 12
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 claims abstract description 10
- 238000001816 cooling Methods 0.000 claims abstract description 10
- 239000003054 catalyst Substances 0.000 claims abstract description 8
- 238000001035 drying Methods 0.000 claims abstract description 7
- 230000009467 reduction Effects 0.000 claims abstract description 7
- 238000001354 calcination Methods 0.000 claims abstract description 6
- 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
- 238000004140 cleaning Methods 0.000 claims abstract description 3
- 239000007787 solid Substances 0.000 claims abstract description 3
- 239000008367 deionised water Substances 0.000 claims description 19
- 229910021641 deionized water Inorganic materials 0.000 claims description 19
- 239000010410 layer Substances 0.000 claims description 19
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 10
- 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
- 239000011572 manganese Substances 0.000 claims description 7
- 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
- 235000006408 oxalic acid Nutrition 0.000 claims description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 4
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 2
- 239000002253 acid Substances 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims description 2
- 229910052749 magnesium Inorganic materials 0.000 claims description 2
- -1 titanium ions Chemical class 0.000 claims 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 9
- 239000000463 material Substances 0.000 abstract description 9
- 229910052710 silicon Inorganic materials 0.000 abstract description 9
- 239000010703 silicon Substances 0.000 abstract description 9
- 239000002131 composite material Substances 0.000 abstract description 8
- 239000007788 liquid Substances 0.000 abstract description 4
- 239000010406 cathode material Substances 0.000 abstract description 2
- 230000001351 cycling effect Effects 0.000 abstract description 2
- 238000005245 sintering 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
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000002156 mixing Methods 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 5
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 4
- 239000005977 Ethylene Substances 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 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
- 230000000694 effects Effects 0.000 description 4
- 229910052744 lithium Inorganic materials 0.000 description 4
- 239000007773 negative electrode material Substances 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- 238000005303 weighing Methods 0.000 description 4
- 230000003139 buffering effect Effects 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- 229910021645 metal ion Inorganic materials 0.000 description 3
- 239000005543 nano-size silicon particle Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- 229910018540 Si C Inorganic materials 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000012300 argon atmosphere Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 230000002708 enhancing effect Effects 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
- 230000008569 process Effects 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 2
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 238000005054 agglomeration 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
- 238000009831 deintercalation Methods 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
- 238000005516 engineering process 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
- 238000011056 performance test Methods 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
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000011856 silicon-based particle Substances 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
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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
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Composite Materials (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Silicon Compounds (AREA)
Abstract
A preparation method of a silicon-carbon composite material comprises the following steps: (1) dissolving ethyl orthosilicate, cetyl 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 a solid, cleaning, drying, and calcining at high temperature to obtain powder D; (4) and reducing the powder D at a high temperature, cooling and washing, 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 material, and a carbon coating layer is coated outside the matrix. According to the invention, a liquid silicon source and a liquid carbon source are fully mixed and then are subjected to reduction sintering to obtain a composite cathode material with uniformly distributed silicon and carbon; meanwhile, the transition metal ions are adopted to dope the base 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 wide attention as electrochemical energy storage devices with the most 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 negative electrode material widely used at present, the silicon material has high theoretical capacity (the theoretical capacity can reach 4200mAh/g), about ten times of that of the carbon material, abundant reserves and lower lithium intercalation potential (the average Si lithium removal potential is 0.4V vs+)。
The silicon material can face huge volume change (> 300%) in the process of lithium intercalation and deintercalation, so that Si particles are cracked, the structure is collapsed, and active substances fall off from a current collector, thereby seriously affecting the cycle performance of the battery; in addition, the silicon material has poor conductivity and large irreversible capacity loss. At present, nano silicon or silicon monoxide is mainly adopted for modification, so that the cycle performance of a silicon-based material can be effectively improved. The nano-size design can obviously slow down the material crushing caused by expansion, but the specific surface area is large, and the agglomeration is easy to occur; in addition, a carbon material is generally added for the purpose of improving conductivity, but the nano silicon and the carbon material are often not uniformly dispersed due to problems of poor surface affinity and non-uniform size.
Disclosure of Invention
The invention aims to solve the technical problem that nano silicon and a carbon material are difficult to uniformly disperse, overcome the defects and shortcomings in the background technology and provide 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:
a preparation method of a silicon-carbon composite material comprises the following steps:
(1) dissolving ethyl orthosilicate, cetyl 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 reducing the powder D at a high temperature, cooling and washing, and coating carbon by vapor deposition to obtain the silicon-carbon composite material.
CTAB (cetyl trimethyl ammonium bromide) plays the role of a surfactant and a dispersant, and meanwhile, the liquid phase synthesis can also ensure that the material is uniformly dispersed, so that the matrix material with uniformly mixed silicon and carbon is obtained.
Preferably, the molar ratio of ethyl orthosilicate to cetyltrimethylammonium bromide in step (1) is from 10:1 to 1:1, more preferably from 8:1 to 1: 1.
Preferably, lithium acetate is added in the step (1), and the molar ratio of the lithium acetate to the ethyl orthosilicate is 1:1-1: 2. Lithium acetate with residual Li in the matrix+The lithium ion battery has the effect of supplementing lithium, assists uniform dispersion during dispersion, and has the effect of promoting the reaction by salting out.
Preferably, the catalyst in the step (1) is oxalic acid, the alcohol solution is an absolute ethanol 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; the volume ratio of the strong ammonia water, the ethanol solution and the deionized water in the step (2) is 1:1:0.5-1:3: 5. The doping of the 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 performed at a high speed of 1000-4000rpm for 10min, and then at a uniform speed of 500-2000rpm for 1-10 h. Preferably, the high-temperature reduction in the step (4) is specifically: placing the powder D in a container, placing metal Ca or Mg powder on the lower layer, and introducing inert gas for 500-800 ℃ high-temperature reduction.
Preferably, the washing in step (4) is specifically: washed with dilute hydrochloric acid, then acid washed with hydrofluoric acid, followed by deionized water.
Under the same technical concept, the invention also provides a silicon-carbon composite material, the silicon-carbon composite material takes a silicon-carbon material as a substrate, the silicon material and the carbon material in the carbon-silicon material substrate are uniformly distributed, transition metal ions are doped in the substrate material, and a carbon coating layer is coated outside the substrate.
The matrix carbon plays a role in buffering silicon-based expansion and enhancing electronic conductivity, and the surface layer coated carbon plays a role in reducing the occurrence of side reactions of the electrolyte and enhancing the conductivity among particles. The two kinds of carbon cooperate to buffer the volume change of the silicon base, and the doping of the metal ions stabilizes the structure of the silicon base material on one hand and enhances the conductivity on the other hand.
Preferably, the mass percentage of carbon in the silicon-carbon material matrix is 1% -30%, the mass percentage of carbon in the silicon-carbon composite material is 1% -50%, more preferably 3% -40%, and the mass percentage of the transition metal ions 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 composite cathode material with uniformly distributed silicon and carbon can be obtained by fully mixing a liquid silicon source and a liquid carbon source and then carrying out reduction sintering; meanwhile, the transition metal ions are adopted to dope the base material, so that the conductivity and the cycling stability of the material are favorably improved.
(2) The loose and porous silicon-based material obtained by the metallothermic reduction is beneficial to resisting the volume change in the circulating process.
(3) This application base member carbon plays the effect of buffering silicon-based inflation and reinforcing electron conductivity, and top layer cladding carbon plays and reduces electrolyte side reaction and takes place and the effect of reinforcing inter-particle conductivity, and two kinds of carbon cooperate the silica-based volume change of buffering.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is an SEM image of a coated Si-C negative electrode material of example 1;
Detailed Description
In order to facilitate an understanding of the invention, reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings, and the scope of the invention is not limited to the following specific embodiments.
Unless otherwise defined, all terms of art 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 limit the scope of the present invention.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
Example 1:
according to a molar ratio of 1:0.5 weighing analytically pure lithium acetate, ethyl orthosilicate and CTAB, uniformly dispersing into absolute ethyl alcohol, adding a small amount of oxalic acid as a catalyst, and adding manganese acetate with a molar ratio of 0.1 and nano titanium dioxide with a 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) quickly adding the solution A into the solution B, stirring at a high speed of 4000rpm for 10min at 1000-. Placing the powder D on the upper layer of the stainless steel double-layer tube 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 at 650 ℃ for reacting for 2 hours, naturally cooling, putting the upper layer powder into 0.1M dilute hydrochloric acid, stirring for 2 hours, taking out, and washing with deionized water; then washing with 0.5 wt% HF solution, washing with deionized water for several times, and drying at 50 deg.C. And (3) placing the dried powder in a reaction furnace, and introducing ethylene gas with the flow rate of 1:1 of 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 matrix of the carbon-silicon material are uniformly distributed, and Mn is doped in the matrix material2+And Ti4+And the matrix is coated with a carbon coating layer.
The mass percentage of carbon in the silicon-carbon material matrix is 20 percent, the mass percentage of carbon in the silicon-carbon composite material is 25 percent, and Mn2+And Ti4+The mass percentage is 3%.
FIG. 1 is an SEM image of a coated Si-C negative electrode material of example 1; it can be seen that the composite material is coated with a carbon coating.
The electrical property test result of the carbon-silicon composite material of the example 1 is that the matrix resistivity is 0.04985 omega cm, the buckling capacity is 1853.3mAh/g, and the capacity retention rate of the cylindrical battery after 200 weeks of circulation is 93.2%.
Example 2
Weighing tetraethoxysilane and CTAB with a molar ratio of 1:1, uniformly dispersing 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 the volume ratio of 2:3:5 to obtain a solution B; and (3) quickly adding the solution A into the solution B, stirring at a high speed for 10min, uniformly stirring for 2h, standing for 2h, performing centrifugal separation to obtain a precipitate, fully washing with deionized water, 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 tube 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 at 650 ℃ for reacting for 2h, naturally cooling, putting the upper layer powder into dilute hydrochloric acid, stirring for 2h, taking out, and washing with deionized water; then washing with HF solution, washing with deionized water for several times, and drying at 50 deg.C. And (3) placing the dried powder in a reaction furnace, keeping the temperature at 850 ℃, and introducing ethylene gas to perform 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 matrix of the carbon-silicon material are uniformly distributed, and Mn is doped in the matrix material2+And Ti4+And the matrix is coated with a carbon coating layer.
The mass percentage of carbon in the silicon-carbon material matrix is 30 percent, the mass percentage of carbon in the silicon-carbon composite material is 35 percent, and Mn is added2+And Ti4+The mass ratio is 2 percent.
The electrical property test result of the carbon-silicon composite material of the embodiment 2 is that the matrix resistivity is 0.08652 omega cm, the buckling capacity is 1795.4mAh/g, and the capacity retention rate of the cylindrical battery is 90.6% after the cylindrical battery is cycled for 200 weeks.
Example 3
Weighing lithium acetate, ethyl orthosilicate and PVP with the 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 the volume ratio of 2:3:5 to obtain a solution B; and (3) quickly adding the solution A into the solution B, stirring at a high speed for 10min, then stirring at a uniform speed for 2h, standing for 2h, then performing centrifugal separation to obtain a precipitate, washing the precipitate with deionized water, calcining the powder at 750 ℃ for 2h in a tubular furnace under argon atmosphere, and naturally cooling to obtain powder D. Placing the powder D on the upper layer of the stainless steel double-layer tube 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 at 650 ℃ for reacting for 2h, naturally cooling, putting the upper layer powder into 0.1M dilute hydrochloric acid, stirring for 2h, taking out, and washing with deionized water; then washing with 0.5 wt% HF solution, washing with deionized water for several times, and drying at 50 deg.C. And (3) placing the dried powder in a reaction furnace, and introducing ethylene gas with the flow rate of 1:1 of 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 matrix of the carbon-silicon material are uniformly distributed, and Mn is doped in the matrix material2+And Ti4+And the matrix is coated with a carbon coating layer.
The electrical property test result of the carbon-silicon composite material of the embodiment 3 is that the matrix resistivity is 0.06742 omega cm, the buckling capacity is 1834.7mAh/g, and the capacity retention rate of the cylindrical battery after 200 weeks of circulation is 92.5%.
Comparative example 1
Weighing tetraethoxysilane and CTAB with the molar ratio of 1:0.5, and uniformly dispersing into absolute ethyl alcohol to obtain a solution A; uniformly mixing concentrated ammonia water, ethanol and deionized water according to the volume ratio of 2:3:5 to obtain a solution B; and (3) quickly adding the solution A into the solution B, stirring at a high speed for 10min, then stirring at a uniform speed for 2h, standing for 2h, then performing centrifugal separation to obtain a precipitate, washing the precipitate with deionized water, calcining the powder at 750 ℃ for 2h in a tubular furnace under argon atmosphere, and naturally cooling to obtain powder D. Placing the powder D on the upper layer of a stainless steel double-layer tube 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 at 650 ℃ for reacting for 2h, naturally cooling, putting the upper layer powder into 0.1M dilute hydrochloric acid, stirring for 2h, taking out, and washing with deionized water; then washing with 0.5 wt% HF solution, washing with deionized water for several times, and drying at 50 deg.C. And (3) placing the dried powder in a reaction furnace, and introducing ethylene gas with the flow rate of 1:1 of nitrogen to react for 2 hours at 850 ℃ to obtain the coated composite material.
Table 1: electrochemical Performance test data for examples 1-3 and comparative examples
Claims (10)
1. The preparation method of the silicon-carbon composite material is characterized by comprising the following steps:
(1) dissolving ethyl orthosilicate, cetyl 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) reducing the powder D at a high temperature, cooling and washing, and coating carbon by a vapor deposition method to obtain the silicon-carbon composite material.
2. The method for preparing a silicon-carbon composite material according to claim 1, wherein the molar ratio of the ethyl orthosilicate to the cetyltrimethylammonium bromide in the step (1) is 10:1 to 1: 1.
3. The method for preparing the silicon-carbon composite material according to claim 1, wherein lithium acetate is added in the step (1), and the molar ratio of the lithium acetate to the ethyl orthosilicate is 1:1-1: 2.
4. The method of claim 1, wherein the catalyst in step (1) is oxalic acid, the alcohol solution is an absolute ethanol solution, and the transition metal ion is manganese and/or titanium.
5. The method for preparing the silicon-carbon composite material according to claim 1, wherein the alcohol-water mixed solution in the step (2) is concentrated ammonia water, an ethanol solution and deionized water, and the volume ratio is 1:1:0.5-1:3: 5.
6. The method for preparing the silicon-carbon composite material according to claim 1, wherein the high-temperature reduction in the step (4) is specifically: placing the powder D in a container, placing metal Ca or Mg powder on the lower layer, and introducing inert gas for 500-800 ℃ high-temperature reduction.
7. The method for preparing the silicon-carbon composite material as claimed in claim 1, wherein the stirring in the step (3) is performed at a high speed of 1000-4000rpm for 10min and then at a uniform speed of 500-2000rpm for 1-10 h; the washing in the step (4) is specifically as follows: washed with dilute hydrochloric acid, then acid washed with hydrofluoric acid, followed by deionized water.
8. A silicon-carbon composite material prepared by the preparation method of any one of claims 1 to 7, wherein the silicon-carbon composite material takes a silicon-carbon material as a matrix, silicon materials and carbon materials in the carbon-silicon material matrix are uniformly distributed, transition metal ions are doped in the matrix material, and the matrix is coated with a carbon coating layer.
9. The silicon-carbon composite material according to claim 8, wherein the mass percentage of carbon in the silicon-carbon material matrix is 1% to 30%, the mass percentage of carbon in the silicon-carbon composite material is 1% to 50%, and the mass percentage of the transition metal ions is 1% to 10%.
10. The silicon-carbon composite material according to claim 8, wherein the transition metal ions are manganese and titanium ions.
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