CN111540896A - Preparation method of silicon-carbon composite negative electrode material - Google Patents
Preparation method of silicon-carbon composite negative electrode material Download PDFInfo
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- CN111540896A CN111540896A CN202010377410.3A CN202010377410A CN111540896A CN 111540896 A CN111540896 A CN 111540896A CN 202010377410 A CN202010377410 A CN 202010377410A CN 111540896 A CN111540896 A CN 111540896A
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- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 239000011868 silicon-carbon composite negative electrode material Substances 0.000 title claims abstract description 13
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 24
- 229920002472 Starch Polymers 0.000 claims abstract description 20
- 235000019698 starch Nutrition 0.000 claims abstract description 20
- 239000008107 starch Substances 0.000 claims abstract description 20
- 238000000034 method Methods 0.000 claims abstract description 19
- 238000002156 mixing Methods 0.000 claims abstract description 19
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000001816 cooling Methods 0.000 claims abstract description 17
- 239000007787 solid Substances 0.000 claims abstract description 16
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 13
- 239000010406 cathode material Substances 0.000 claims abstract description 12
- 239000005539 carbonized material Substances 0.000 claims abstract description 11
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 11
- 239000010439 graphite Substances 0.000 claims abstract description 11
- 238000002791 soaking Methods 0.000 claims abstract description 11
- 238000003756 stirring Methods 0.000 claims abstract description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 11
- 238000010438 heat treatment Methods 0.000 claims description 39
- 239000000243 solution Substances 0.000 claims description 37
- 239000000463 material Substances 0.000 claims description 34
- 239000005543 nano-size silicon particle Substances 0.000 claims description 18
- 239000007789 gas Substances 0.000 claims description 15
- 230000001681 protective effect Effects 0.000 claims description 15
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 14
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 12
- 239000006185 dispersion Substances 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 9
- 239000010405 anode material Substances 0.000 claims description 7
- 229910052757 nitrogen Inorganic materials 0.000 claims description 7
- 229910052786 argon Inorganic materials 0.000 claims description 6
- 229910052734 helium Inorganic materials 0.000 claims description 6
- 239000001307 helium Substances 0.000 claims description 6
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 6
- 229910052743 krypton Inorganic materials 0.000 claims description 6
- DNNSSWSSYDEUBZ-UHFFFAOYSA-N krypton atom Chemical compound [Kr] DNNSSWSSYDEUBZ-UHFFFAOYSA-N 0.000 claims description 6
- 229910052754 neon Inorganic materials 0.000 claims description 6
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 claims description 6
- 229910052704 radon Inorganic materials 0.000 claims description 6
- SYUHGPGVQRZVTB-UHFFFAOYSA-N radon atom Chemical compound [Rn] SYUHGPGVQRZVTB-UHFFFAOYSA-N 0.000 claims description 6
- 229910052724 xenon Inorganic materials 0.000 claims description 6
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 claims description 6
- 229910021383 artificial graphite Inorganic materials 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 5
- 239000011248 coating agent Substances 0.000 claims description 4
- 238000000576 coating method Methods 0.000 claims description 4
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 claims description 3
- 229930006000 Sucrose Natural products 0.000 claims description 3
- 238000003763 carbonization Methods 0.000 claims description 3
- 229910021382 natural graphite Inorganic materials 0.000 claims description 3
- 239000011347 resin Substances 0.000 claims description 3
- 229920005989 resin Polymers 0.000 claims description 3
- 239000002153 silicon-carbon composite material Substances 0.000 claims description 3
- 239000011295 pitch Substances 0.000 claims description 2
- 239000005720 sucrose Substances 0.000 claims description 2
- 239000011870 silicon-carbon composite anode material Substances 0.000 claims 9
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 19
- 229910052710 silicon Inorganic materials 0.000 abstract description 19
- 239000010703 silicon Substances 0.000 abstract description 19
- 239000007773 negative electrode material Substances 0.000 abstract description 11
- 239000002210 silicon-based material Substances 0.000 abstract description 9
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 5
- 238000007599 discharging Methods 0.000 abstract description 5
- 230000000694 effects Effects 0.000 abstract description 5
- 239000013013 elastic material Substances 0.000 abstract description 5
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 5
- 238000012986 modification Methods 0.000 abstract description 3
- 230000004048 modification Effects 0.000 abstract description 3
- 239000011856 silicon-based particle Substances 0.000 abstract description 3
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 2
- 239000011247 coating layer Substances 0.000 abstract description 2
- 230000007547 defect Effects 0.000 abstract description 2
- 229910052744 lithium Inorganic materials 0.000 abstract description 2
- 238000010298 pulverizing process Methods 0.000 abstract description 2
- 230000005611 electricity Effects 0.000 abstract 1
- 239000000203 mixture Substances 0.000 abstract 1
- 238000000352 supercritical drying Methods 0.000 abstract 1
- 239000010426 asphalt Substances 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 2
- 229960004793 sucrose Drugs 0.000 description 2
- 229910003481 amorphous carbon Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
Classifications
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/02—Silicon
-
- 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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
-
- 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
A preparation method of a silicon-carbon composite negative electrode material relates to a preparation method of a negative electrode material. The invention aims to solve the technical problems that volume expansion is easy to generate in the process of charging and discharging of silicon, so that silicon particle pulverization is caused, the cycle life of a lithium ion battery is short, the service performance is poor, and the exertion of the silicon effect is inhibited if surface modification is carried out on a silicon material. The method comprises the following steps: mixing starch with water, stirring, dispersing, cooling, and standing; soaking the mixture in an ethanol solution and absolute ethanol, collecting white solids, performing supercritical drying, crushing, mixing with a carbon source, keeping the temperature constant at 180-300 ℃, 450-600 ℃, 1000-1200 ℃, cooling to room temperature, and mixing the carbonized material with a graphite cathode material to obtain the graphite cathode material. The lithium-ion battery provided by the invention uses the elastic material, can conduct electricity, has lithium storage capacity, is filled between the coating layer and the silicon material, keeps good conductivity, can play the role of silicon, and avoids the defects of silicon. The invention belongs to the field of preparation of negative electrode materials.
Description
Technical Field
The invention relates to a preparation method of a negative electrode material.
Background
The theoretical gram capacity of silicon is as high as 4200mAh/g, and the silicon is a novel generation anode material with great potential. However, silicon is easy to generate volume expansion (more than 300%) in the charging and discharging processes, so that silicon particles are pulverized, and the exposed silicon continuously consumes electrolyte to generate a new SEI film in the charging and discharging processes, so that the lithium ion battery has a short cycle life and poor service performance, and the problems seriously affect the wide application of the silicon material in the aspect of the lithium ion battery.
The surface modification is carried out on the silicon material, the volume expansion of the silicon is restrained, and a certain inhibition effect is achieved, but the exertion of the effect of the silicon is also severely inhibited, and the characteristic of high gram capacity of the silicon cannot be exerted.
Disclosure of Invention
The invention aims to solve the technical problems that silicon is easy to expand in volume in the charging and discharging process to cause silicon particle pulverization, and exposed silicon continuously consumes electrolyte to generate a new SEI film in the charging and discharging process, so that the lithium ion battery has low cycle life and poor service performance, and if the surface modification is carried out on a silicon material to inhibit the exertion of the silicon effect, the silicon cannot exert the high gram capacity of the silicon material.
The preparation method of the silicon-carbon composite negative electrode material comprises the following steps:
firstly, placing nano silicon and water into a dispersion machine according to a mass ratio of 1 (0.5-5) to be uniformly dispersed to obtain a nano silicon aqueous solution;
simultaneously mixing starch and water according to the mass ratio of 1 (0.1-10), and stirring for 1-20 minutes at the temperature of 85-95 ℃;
thirdly, adding the nano-silicon aqueous solution obtained in the first step and the starch solution obtained in the second step into a dispersion machine according to the mass ratio of nano-silicon to starch (0.5-5) to (0.1-10), and continuously dispersing until the nano-silicon aqueous solution and the starch solution are uniform to form a gel solution;
fourthly, cooling the gel solution to room temperature, and standing for 8-48 hours;
fifthly, soaking the gel solution obtained in the fourth step in an ethanol solution until the gel turns into a white solid, continuously soaking the gel solution in absolute ethanol for 1-24 hours, and collecting the white solid;
sixthly, putting the obtained white solid into a supercritical dryer for drying, and crushing the dried material to obtain D50 (13-25 microns);
seventhly, uniformly mixing the materials crushed in the step six with a carbon source according to the mass ratio of (2-15) to 1;
heating the mixed material in a reaction kettle to 180-400 ℃ at a heating rate of not more than 10 ℃ per minute, keeping the temperature for 1-3 hours, continuously heating to 450-600 ℃ at a heating rate of not more than 5 ℃ per minute, keeping the temperature for 1-3 hours, stirring at a speed of 100-200 revolutions per minute in the whole process, introducing protective gas, finishing carbon source coating, and cooling to room temperature to obtain a coated material;
heating the coated material to 1000-1200 ℃ at a heating rate of not more than 6 ℃ per minute in a protective gas atmosphere, keeping the temperature for 1-5 hours, and cooling to room temperature to obtain a carbonized material;
and tenthly, mixing the carbonized material with the graphite cathode material to obtain the silicon-carbon composite cathode material.
And seventhly, the carbon source is asphalt, resin or cane sugar.
And step eight, the protective gas is one or more of nitrogen, helium, neon, argon, krypton, xenon and radon.
And step nine, the protective gas is one or more of nitrogen, helium, neon, argon, krypton, xenon and radon.
And step ten, the graphite cathode material is an artificial graphite cathode material or a natural graphite cathode material.
And (3) mixing the material subjected to carbonization in the step ten with the graphite cathode material according to the mass ratio of 1 (1-99).
The elastic material is used, so that the electric conduction can be realized, a certain lithium storage capacity is realized, the elastic material is filled between the coating layer and the silicon material, when the volume of the silicon expands, the elastic material contracts, and when the volume of the silicon contracts, the elastic material recovers to the original state, the close connection with the silicon material is kept at any time, and the good electric conduction performance is kept, so that the function of the silicon can be exerted, and the defect of the silicon is avoided.
The carbon gel material obtained by processing the starch gel solution meets the above-mentioned characteristics, and can well exert the characteristics of the silicon-carbon composite negative electrode material when being matched with a silicon material.
Detailed Description
The technical solution of the present invention is not limited to the following specific embodiments, but includes any combination of the specific embodiments.
The first embodiment is as follows: the preparation method of the silicon-carbon composite negative electrode material of the embodiment is as follows:
firstly, placing nano silicon and water into a dispersion machine according to a mass ratio of 1 (0.5-5) to be uniformly dispersed to obtain a nano silicon aqueous solution;
simultaneously mixing starch and water according to the mass ratio of 1 (0.1-10), and stirring for 1-20 minutes at the temperature of 85-95 ℃;
thirdly, adding the nano-silicon aqueous solution obtained in the first step and the starch solution obtained in the second step into a dispersion machine according to the mass ratio of nano-silicon to starch (0.5-5) to (0.1-10), and continuously dispersing until the nano-silicon aqueous solution and the starch solution are uniform to form a gel solution;
fourthly, cooling the gel solution to room temperature, and standing for 8-48 hours;
fifthly, soaking the gel solution obtained in the fourth step in an ethanol solution until the gel turns into a white solid, continuously soaking the gel solution in absolute ethanol for 1-24 hours, and collecting the white solid;
sixthly, putting the obtained white solid into a supercritical dryer for drying, and crushing the dried material to obtain D50 (13-25 microns);
seventhly, uniformly mixing the materials crushed in the step six with a carbon source according to the mass ratio of (2-15) to 1;
heating the mixed material in a reaction kettle to 180-400 ℃ at a heating rate of not more than 10 ℃ per minute, keeping the temperature for 1-3 hours, continuously heating to 450-600 ℃ at a heating rate of not more than 5 ℃ per minute, keeping the temperature for 1-3 hours, stirring at a speed of 100-200 revolutions per minute in the whole process, introducing protective gas, finishing carbon source coating, and cooling to room temperature to obtain a coated material;
heating the coated material to 1000-1200 ℃ at a heating rate of not more than 6 ℃ per minute in a protective gas atmosphere, keeping the temperature for 1-5 hours, and cooling to room temperature to obtain a carbonized material;
and tenthly, mixing the carbonized material with the graphite cathode material to obtain the silicon-carbon composite cathode material.
The second embodiment is as follows: the difference between the present embodiment and the first embodiment is that the carbon source in the seventh embodiment is pitch, resin or sucrose. The rest is the same as the first embodiment.
The third concrete implementation mode: the present embodiment differs from the first or second embodiment in that in the eighth step, the heating is performed at a temperature increase rate of not more than 10 ℃ per minute to 400 ℃. The others are the same as in the first or second embodiment.
The fourth concrete implementation mode: the present embodiment is different from the first to third embodiments in that the temperature is continuously raised to 600 ℃ at a temperature raising rate of not more than 5 ℃ per minute in step eight. The rest is the same as one of the first to third embodiments.
The fifth concrete implementation mode: the difference between this embodiment and one of the first to the fourth embodiments is that in the step eight, the protective gas is one or more of nitrogen, helium, neon, argon, krypton, xenon, and radon. The rest is the same as one of the first to fourth embodiments.
The sixth specific implementation mode: the difference between this embodiment and one of the first to fifth embodiments is that in the ninth step, the protective gas is one or more of nitrogen, helium, neon, argon, krypton, xenon, and radon. The rest is the same as one of the first to fifth embodiments.
The seventh embodiment: the present embodiment is different from the first to sixth embodiments in that in the ninth step, the heating is performed to 1050-1150 ℃ at a heating rate of not more than 6 ℃ per minute. The rest is the same as one of the first to sixth embodiments.
The specific implementation mode is eight: the present embodiment is different from the first to seventh embodiments in that the heating is performed to 1100 ℃ at a heating rate of not more than 6 ℃ per minute in the ninth step. The rest is the same as one of the first to seventh embodiments.
The specific implementation method nine: the present embodiment is different from the first to eighth embodiments in that the graphite negative electrode material in the tenth step is an artificial graphite negative electrode material or a natural graphite negative electrode material. The rest is the same as the first to eighth embodiments.
The detailed implementation mode is ten: the embodiment is different from one of the first to ninth embodiments in that the material subjected to carbonization in the step ten and the graphite negative electrode material are mixed according to the mass ratio of 1 (1-99). The rest is the same as one of the first to ninth embodiments. The following experiments are adopted to verify the effect of the invention:
experiment one:
the preparation method of the silicon-carbon composite negative electrode material comprises the following steps:
firstly, putting nano silicon and water into a dispersion machine according to the mass ratio of 1:2 to be uniformly dispersed;
simultaneously mixing starch and water according to the mass ratio of 1:1, and stirring for 10 minutes at the temperature of 95 ℃;
thirdly, adding the starch solution obtained in the second step into a dispersion machine, and continuously dispersing until the starch solution is uniform to form a gel solution;
fourthly, cooling the gel solution to room temperature, and standing for 24 hours;
fifthly, soaking the gel solution obtained in the fourth step in an ethanol solution until the gel turns into a white solid, continuously soaking the gel solution in absolute ethanol for 10 hours, and collecting the white solid;
sixthly, putting the obtained white solid into a supercritical dryer for drying, and crushing the dried material into D50-15 microns;
seventhly, uniformly mixing the materials crushed in the step six with asphalt according to the mass ratio of 4: 1;
heating the mixed material in a reaction kettle to 350 ℃ at a heating rate of 4 ℃/min, keeping the temperature for 1 hour, continuously heating to 600 ℃ at a heating rate of 2 ℃/min, keeping the temperature for 2 hours, stirring at a speed of 150 revolutions per minute in the whole process, introducing nitrogen, and cooling to obtain a coated material;
heating the coated material to 1100 ℃ at a heating rate of 4 ℃/min under the atmosphere of protective gas, keeping the temperature for 2 hours, and cooling to room temperature to obtain a carbonized material;
and tenthly, mixing the carbonized material with the artificial graphite negative electrode material according to the mass ratio of 1:7 to obtain the silicon-carbon composite negative electrode material.
The material obtained in the ninth step is a mixed material of nano silicon and amorphous carbon, the theoretical calculation value of the mass ratio is about 11:9, and the measured gram volume of the material is 2357.4mAh/g, which is close to the theoretical calculation value;
the gram capacity of the final silicon-carbon composite negative electrode material obtained in the step ten is 595.3mAh/g, the service performance of the current negative electrode material can be met, and the cost can be more reasonable than that of the material control in the step nine.
Experiment two:
the preparation method of the silicon-carbon composite negative electrode material comprises the following steps:
firstly, putting nano silicon and water into a dispersion machine according to the mass ratio of 1:1.5 to be uniformly dispersed;
simultaneously mixing starch and water according to the mass ratio of 1:1.5, and stirring for 10 minutes at the temperature of 95 ℃;
thirdly, adding the starch solution obtained in the second step into a dispersion machine, and continuously dispersing until the starch solution is uniform to form a gel solution;
fourthly, cooling the gel solution to room temperature, and standing for 24 hours;
fifthly, soaking the gel solution obtained in the fourth step in an ethanol solution until the gel turns into a white solid, continuously soaking the gel solution in absolute ethanol for 10 hours, and collecting the white solid;
sixthly, putting the obtained white solid into a supercritical dryer for drying, and crushing the dried material to obtain D50 (17 microns);
seventhly, uniformly mixing the materials crushed in the step six with asphalt according to the mass ratio of 7: 3;
heating the mixed material in a reaction kettle to 350 ℃ at a heating rate of 4 ℃/min, keeping the temperature for 1 hour, heating to 600 ℃ at a heating rate of 2 ℃/min, keeping the temperature for 2 hours, stirring at a speed of 150 rpm in the whole process, introducing protective gas to complete carbon source coating, and cooling to room temperature to obtain a coated material;
heating the coated material to 1100 ℃ at a heating rate of 4 ℃/min under the atmosphere of protective gas, keeping the temperature for 2 hours, and cooling to room temperature to obtain a carbonized material;
and tenthly, mixing the carbonized material with the artificial graphite negative electrode material according to the mass ratio of 1:7 to obtain the silicon-carbon composite negative electrode material.
The gram capacity of the material obtained in the ninth step is 2068.0mAh/g, the carbon source content is increased, the gram capacity is reduced to some extent, but the structural stability is higher, and the rate capability is better.
And step ten, the gram capacity of the finally obtained composite negative electrode material is 561.9 mAh/g.
Claims (10)
1. A preparation method of a silicon-carbon composite negative electrode material is characterized in that the preparation method of the silicon-carbon composite negative electrode material comprises the following steps:
firstly, placing nano silicon and water into a dispersion machine according to a mass ratio of 1 (0.5-5) to be uniformly dispersed to obtain a nano silicon aqueous solution;
simultaneously mixing starch and water according to the mass ratio of 1 (0.1-10), and stirring for 1-20 minutes at the temperature of 85-95 ℃;
thirdly, adding the nano-silicon aqueous solution obtained in the first step and the starch solution obtained in the second step into a dispersion machine according to the mass ratio of nano-silicon to starch (0.5-5) to (0.1-10), and continuously dispersing until the nano-silicon aqueous solution and the starch solution are uniform to form a gel solution;
fourthly, cooling the gel solution to room temperature, and standing for 8-48 hours;
fifthly, soaking the gel solution obtained in the fourth step in an ethanol solution until the gel turns into a white solid, continuously soaking the gel solution in absolute ethanol for 1-24 hours, and collecting the white solid;
sixthly, putting the obtained white solid into a supercritical dryer for drying, and crushing the dried material to obtain D50 (13-25 microns);
seventhly, uniformly mixing the materials crushed in the step six with a carbon source according to the mass ratio of (2-15) to 1;
heating the mixed material in a reaction kettle to 180-400 ℃ at a heating rate of not more than 10 ℃ per minute, keeping the temperature for 1-3 hours, continuously heating to 450-600 ℃ at a heating rate of not more than 5 ℃ per minute, keeping the temperature for 1-3 hours, stirring at a speed of 100-200 revolutions per minute in the whole process, introducing protective gas, finishing carbon source coating, and cooling to room temperature to obtain a coated material;
heating the coated material to 1000-1200 ℃ at a heating rate of not more than 6 ℃ per minute in a protective gas atmosphere, keeping the temperature for 1-5 hours, and cooling to room temperature to obtain a carbonized material;
and tenthly, mixing the carbonized material with the graphite cathode material to obtain the silicon-carbon composite cathode material.
2. The method for preparing the silicon-carbon composite anode material according to claim 1, wherein the carbon source in the seventh step is pitch, resin or sucrose.
3. The method for preparing a silicon-carbon composite anode material according to claim 1, wherein the heating is carried out to 400 ℃ at a heating rate of not more than 10 ℃ per minute in step eight.
4. The method for preparing the silicon-carbon composite anode material according to claim 1, wherein the temperature is continuously increased to 600 ℃ in the eighth step at a temperature increasing rate of not more than 5 ℃ per minute.
5. The method for preparing a silicon-carbon composite anode material according to claim 1, wherein the protective gas in the step eight is one or more of nitrogen, helium, neon, argon, krypton, xenon and radon.
6. The method for preparing a silicon-carbon composite anode material according to claim 1, wherein the protective gas in the ninth step is one or more of nitrogen, helium, neon, argon, krypton, xenon and radon.
7. The preparation method of the silicon-carbon composite anode material according to claim 1, wherein in the ninth step, the anode material is heated to 1050-1150 ℃ at a heating rate of not more than 6 ℃ per minute.
8. The method for preparing a silicon-carbon composite anode material according to claim 1, wherein in the ninth step, the anode material is heated to 1100 ℃ at a heating rate of not more than 6 ℃ per minute.
9. The method for preparing the silicon-carbon composite anode material according to claim 1, wherein the graphite anode material in the step ten is an artificial graphite anode material or a natural graphite anode material.
10. The preparation method of the silicon-carbon composite anode material according to claim 1, characterized in that the material subjected to carbonization in the step ten and the graphite anode material are mixed according to a mass ratio of 1 (1-99).
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| CN202010377410.3A CN111540896A (en) | 2020-05-07 | 2020-05-07 | Preparation method of silicon-carbon composite negative electrode material |
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