Preparation method of silicon-carbon negative electrode material

Abstract

The invention relates to the technical field of silicon-carbon negative electrode materials, in particular to a preparation method of a silicon-carbon negative electrode material, which comprises the following steps: S1, preparation of a mixture: the raw materials of the mixture comprise graphene oxide, silicon nanoparticles, graphite, conductive carbon black and phenolic resin, and the mixture is prepared by mixing the raw materials according to a mass ratio of 1: (2-3): 1: (0.2-0.4): (0.1-0.2). According to the invention, quinoa polyphenol and 3, 4-ethylenedioxythiophene are subjected to a polymerization reaction to generate a conductive polymer, the conductive polymer can cooperate with a carbon-based material to generate a three-dimensional conductive network, the electron transmission efficiency in the negative electrode material is improved, dopamine hydrochloride can generate polydopamine in an aminomethane buffer solution, and the conductivity of the negative electrode material is improved. Functional groups in quinoa polyphenol and polydopamine preferentially react with lithium ions in the first circulation to form a stable SEI membrane structure, so that the use performance of the silicon-carbon negative electrode material is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon-carbon anode materials, and specifically to a preparation method of a silicon-carbon anode material. Background Art

[0002] The silicon-carbon anode material is a new type of anode material for lithium batteries, which is composed of silicon and carbon. It combines the advantages of high specific capacity of silicon and good electrical conductivity and cycle stability of carbon, can make up for the defects of large volume expansion and poor electrical conductivity of single silicon materials, and has significant potential in the fields of new energy vehicles, energy storage, etc.

[0003] In the prior art, during the preparation process of the silicon-carbon anode material, high-temperature carbonization treatment is required. High temperature will affect the pore structure of the silicon-carbon anode material, affect the lithium-ion transport efficiency, and thus affect the electrical conductivity of the silicon-carbon anode material. Based on this, the present invention provides a preparation method of a silicon-carbon anode material. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a silicon-carbon anode material. The silicon-carbon anode material prepared by the present invention not only has good initial charge and discharge capacity, but also has excellent initial Coulomb efficiency, effectively improving the use performance of the silicon-carbon anode material.

[0005] To achieve the above purpose, the present invention provides the following technical solutions: A preparation method of a silicon-carbon anode material, comprising the following steps: S1: Preparation of a mixture. The raw materials of the mixture include graphene oxide, silicon nanoparticles, graphite, conductive carbon black, and phenolic resin. The raw materials are mixed to obtain a mixture. Among them, the mass ratio of each raw material is 1:(2-3):1:(0.2-0.4):(0.1-0.2); S2: Preparation of an additive. The raw materials of the additive include quinoa polyphenols, 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, deionized water, aminomethane buffer solution, and dopamine hydrochloride; S3: Mixing treatment. The mixture and the additive are mixed to complete the mixing treatment to obtain a crude material; S4: Carbonization treatment. The crude material is carbonized to obtain a base material; S5: Graphitization treatment. The base material is graphitized to obtain a silicon-carbon anode material.

[0006] Further, the quinoa polyphenols are prepared by the following method: Select quinoa as the raw material, crush the quinoa, mix the obtained product with petroleum ether, oscillate for 2-4 h, filter and dry the obtained product to obtain quinoa powder, and further process the quinoa powder to obtain quinoa polyphenols.

[0007] Further, the mass of petroleum ether is 3 to 4 times the mass of quinoa after pulverization, and the particle size of the pulverized quinoa is 10 to 40 μm.

[0008] Further, the method for further treating the quinoa powder is as follows: the quinoa powder and the treatment liquid are added into a mixer, and the mixer is set to stir at 200 - 300 r / min for 10 - 20 min. The obtained product is subjected to ultrasonic microwave extraction treatment. The ultrasonic microwave extraction treatment is set at a temperature of 40 - 50 °C, an ultrasonic power of 100 - 200 W, a microwave power of 80 - 100 Hz, and a treatment time of 30 - 40 min. The obtained product is added into a centrifuge, and the centrifuge is set to centrifuge at 4000 - 6000 r / min for 6 - 10 min. The supernatant is obtained from the centrifuged product. After the supernatant is mixed with PBS buffer solution, freeze-drying treatment is carried out to obtain quinoa polyphenols. Among them, the mass of the treatment liquid is 6 - 8 times the mass of the quinoa powder, and the mass of the PBS buffer solution is 40 - 60% of the mass of the supernatant.

[0009] Further, the treatment liquid is prepared by the following method: ethanol, deionized water, 1-ethyl-3-methylimidazolium tetrafluoroborate, and ferric chloride are added into a mixer, and the mixer is set to stir at 300 - 400 r / min for 20 - 30 min to obtain the treatment liquid. Among them, the particle size of ferric chloride is 2 - 10 nm, and the mass ratio of ethanol, deionized water, 1-ethyl-3-methylimidazolium tetrafluoroborate, and ferric chloride is 1:1.2:(0.8 - 0.12):(0.1 - 0.2).

[0010] Further, the method for preparing the additive is as follows: 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, and deionized water are added into a mixer, and the mixer is set to stir at 80 - 120 r / min for 10 - 20 min. The obtained product is subjected to ultrasonic treatment to obtain an emulsion. The emulsion is added into a beaker. Under ice bath conditions, quinoa polyphenols and deionized water are added into the beaker, and a magnetic stirrer is used to set a constant temperature stirring at 100 - 200 r / min for 10 - 20 h. The obtained product is added into a centrifuge, and the centrifuge is set to centrifuge at 8000 - 10000 r / min for 16 - 20 min. The precipitate is obtained from the centrifuged product. The precipitate is washed alternately with deionized water and ethanol, and the obtained product is subjected to vacuum drying treatment to obtain particulate matter. After the particulate matter and aminomethane buffer solution are mixed, ultrasonic treatment is set at 200 - 300 W for 20 - 30 min. The obtained product is added into a mixer, and dopamine hydrochloride is added into the mixer. The mixer is set to stir at 300 - 400 r / min for 20 - 30 min. The obtained product is added into a centrifuge, and the centrifuge is set to centrifuge at 6000 - 8000 r / min for 6 - 10 min. The solid matter is obtained from the centrifugation treatment. The solid matter is washed with deionized water, and the obtained product is subjected to vacuum drying treatment to obtain the additive.

[0011] Further, the mass ratio of 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, and deionized water is 1:(0.4 - 0.6):(40 - 60), the mass of quinoa polyphenol is 2 - 3 times the mass of 3,4-ethylenedioxythiophene, the mass ratio of quinoa polyphenol to deionized water is 1:(3 - 5), the mass of aminomethane buffer solution is 20 - 40 times the mass of the particulate matter, and the mass of dopamine hydrochloride is 8 - 12% of the mass of the particulate matter.

[0012] Further, the method of the mixing treatment is as follows: after the mixture and the additive are mixed, ball milling treatment is carried out for 10 - 16 h, and then it is sent into an oven, and the oven is set at 80 - 100 °C for drying treatment for 4 - 6 h to complete the mixing treatment and obtain the crude material, wherein the mass ratio of the mixture to the additive is 1:(0.2 - 0.3).

[0013] Further, the method of the carbonization treatment is as follows: the crude material is sent into a carbonization furnace, the set heating rate is 2 - 6 °C / min, heated to 400 - 600 °C, and kept warm for 40 - 60 min, then the set heating rate is 10 - 20 °C / min, heated to 800 - 1000 °C, and kept warm for 6 - 8 h to complete the carbonization treatment and obtain the base material.

[0014] Further, the method of the graphitization treatment is as follows: the set heating rate is 30 - 40 °C / min, heated to 2800 - 3000 °C, and kept warm for 6 - 10 h to complete the graphitization treatment and obtain the silicon-carbon anode material.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In the present invention, during the preparation process of the silicon-carbon anode material, through further mixing treatment of the mixture, by adding the additive in the mixing treatment, quinoa polyphenol and 3,4-ethylenedioxythiophene generate a conductive polymer through a polymerization reaction, and this conductive polymer can cooperate with the carbon-based material to generate a three-dimensional conductive network, enhancing the electron transport efficiency in the anode material. At the same time, dopamine hydrochloride can generate polydopamine in the aminomethane buffer solution, and the functional groups in quinoa polyphenol and polydopamine react with lithium ions preferentially in the first cycle to form a stable SEI film structure, effectively improving the use performance of the silicon-carbon anode material.

[0016] 2. In the present invention, during the preparation process of quinoa polyphenol, through the synergistic extraction of ultrasound and microwave, the extraction time can be shortened and the release of polyphenols can be improved. Using the good solubility and conductivity of 1-ethyl-3-methylimidazolium tetrafluoroborate, after mixing with ethanol as the extraction solvent, the chelating ability of polyphenols can form a conductive metal complex, and ferric chloride can generate conductive nanoparticles after carbonization treatment, improving the overall conductivity of the silicon-carbon anode material. Description of the Drawings

[0017] Figure 1 Provide a flowchart for a method of preparing a silicon-carbon anode material for an invention. Detailed implementation manners

[0018] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0019] Among them, it should be noted that the raw materials used in the following embodiments are all commercially available raw materials.

[0020] Embodiment 1:

[0021] S1: Preparation of the mixture. The raw materials of the mixture include graphene oxide, silicon nanoparticles, graphite, conductive carbon black, and phenolic resin. The raw materials are mixed to obtain the mixture. Among them, the mass ratio of each raw material is 1:2:1:0.2:0.1; S2: Preparation of the additive. The raw materials of the additive include quinoa polyphenols, 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, deionized water, aminomethane buffer solution, and dopamine hydrochloride; Quinoa polyphenols are prepared by the following method: Select quinoa as the raw material, crush the quinoa, mix the obtained product with petroleum ether, oscillate for 2 h, filter the obtained product by suction and dry it to obtain quinoa powder. The quinoa powder is further processed to obtain quinoa polyphenols. The mass of petroleum ether is 3 times the mass of the crushed quinoa. The particle size of the crushed quinoa is 10 μm. The quinoa powder and the treatment liquid are added to a mixer, and the mixer is set to stir at 200 r / min for 10 min. The obtained product is subjected to ultrasonic microwave extraction treatment. The ultrasonic microwave extraction treatment is set at a temperature of 40 °C, an ultrasonic power of 100 W, a microwave power of 80 Hz, and a treatment time of 30 min. The obtained product is added to a centrifuge, and the centrifuge is set to centrifuge at 4000 r / min for 6 min. The supernatant is obtained from the centrifuged product. After the supernatant is mixed with PBS buffer solution, it is freeze-dried to obtain quinoa polyphenols. Among them, the mass of the treatment liquid is 6 times the mass of the quinoa powder, and the mass of PBS buffer solution is 40% of the mass of the supernatant; The treatment liquid is prepared by the following method: Ethanol, deionized water, 1-ethyl-3-methylimidazolium tetrafluoroborate, and ferric chloride are added to a mixer, and the mixer is set to stir at 300 r / min for 20 min to obtain the treatment liquid. Among them, the particle size of ferric chloride is 2 nm, and the mass ratio of ethanol, deionized water, 1-ethyl-3-methylimidazolium tetrafluoroborate, and ferric chloride is 1:1.2:0.8:0.1; The method for preparing the additive is as follows: 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, and deionized water are added to a mixer. The mixer is set to stir at 80 r / min for 10 min. The obtained product is subjected to ultrasonic treatment to obtain an emulsion. The emulsion is added to a beaker. Under ice bath conditions, quinoa polyphenols and deionized water are added to the beaker. A magnetic stirrer is used to set a constant temperature stirring at 100 r / min for 10 h. The obtained product is added to a centrifuge. The centrifuge is set to centrifuge at 8000 r / min for 16 min. A precipitate is obtained from the centrifuged product. The precipitate is washed alternately with deionized water and ethanol. The obtained product is subjected to vacuum drying to obtain particulate matter. The particulate matter and aminomethane buffer solution are mixed and set to be ultrasonically treated at 200 W for 20 min. The obtained product is added to a mixer. Dopamine hydrochloride is added to the mixer. The mixer is set to stir at 300 r / min for 20 min. The obtained product is added to a centrifuge. The centrifuge is set to centrifuge at 6000 r / min for 6 min. A solid is obtained from the centrifugation treatment. The solid is washed with deionized water. The obtained product is subjected to vacuum drying to obtain the additive. Among them, the mass ratio of 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, and deionized water is 1:0.4:40. The mass of quinoa polyphenols is twice the mass of 3,4-ethylenedioxythiophene. The mass ratio of quinoa polyphenols to deionized water is 1:3. The mass of aminomethane buffer solution is 20 times the mass of the particulate matter. The mass of dopamine hydrochloride is 8% of the mass of the particulate matter; S3: Mixing treatment. The mixture and the additive are mixed to complete the mixing treatment and obtain the crude material; The method for the mixing treatment is as follows: After the mixture and the additive are mixed, ball milling treatment is carried out for 10 h. Then it is sent into an oven. The oven is set to dry at 80 °C for 4 h to complete the mixing treatment and obtain the crude material. Among them, the mass ratio of the mixture to the additive is 1:0.2; S4: Carbonization treatment. The crude material is subjected to carbonization treatment to obtain the base material; The method for the carbonization treatment is as follows: The crude material is sent into a carbonization furnace. The heating rate is set to 2 °C / min and heated to 400 °C, and held for 40 min. Then the heating rate is set to 10 °C / min and heated to 800 °C, and held for 6 h to complete the carbonization treatment and obtain the base material; S5: Graphitization treatment. The base material is subjected to graphitization treatment to obtain the silicon-carbon negative electrode material; The method for the graphitization treatment is as follows: The heating rate is set to 30 °C / min and heated to 2800 °C, and held for 6 h to complete the graphitization treatment and obtain the silicon-carbon negative electrode material.

[0022] Example 2:

[0023] S1: Preparation of the mixture. The raw materials of the mixture include graphene oxide, silicon nanoparticles, graphite, conductive carbon black, and phenolic resin. The raw materials are mixed to obtain the mixture. Among them, the mass ratio of each raw material is 1:2.5:1:0.3:0.15; S2: Preparation of the additive. The raw materials of the additive include quinoa polyphenols, 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, deionized water, aminomethane buffer solution, and dopamine hydrochloride; The quinoa polyphenols are prepared by the following method: Select quinoa as the raw material. The quinoa is crushed. The obtained product is mixed with petroleum ether and oscillated for 3 h. The obtained product is filtered and dried to obtain quinoa powder. The quinoa powder is further processed to obtain quinoa polyphenols. The mass of petroleum ether is 3.5 times the mass of the crushed quinoa. The particle size of the crushed quinoa is 25 μm. The quinoa powder and the treatment liquid are added to a mixer. The mixer is set to stir at 250 r / min for 15 min. The obtained product is subjected to ultrasonic microwave extraction treatment. The ultrasonic microwave extraction treatment is set at a temperature of 45 °C, an ultrasonic power of 150 W, a microwave power of 90 Hz, and a treatment time of 35 min. The obtained product is added to a centrifuge. The centrifuge is set to centrifuge at 5000 r / min for 8 min. The supernatant is obtained from the centrifuged product. After the supernatant is mixed with PBS buffer solution, it is freeze-dried to obtain quinoa polyphenols. Among them, the mass of the treatment liquid is 7 times the mass of the quinoa powder, and the mass of the PBS buffer solution is 50% of the mass of the supernatant; The treatment liquid is prepared by the following method: Ethanol, deionized water, 1-ethyl-3-methylimidazolium tetrafluoroborate, and ferric chloride are added to a mixer. The mixer is set to stir at 350 r / min for 25 min to obtain the treatment liquid. Among them, the particle size of ferric chloride is 6 nm, and the mass ratio of ethanol, deionized water, 1-ethyl-3-methylimidazolium tetrafluoroborate, and ferric chloride is 1:1.2:0.1:0.15; The method for preparing the additive is as follows: 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, and deionized water are added to a mixer. The mixer is set to stir at 100 r / min for 15 min. The resulting product is subjected to ultrasonic treatment to obtain an emulsion. The emulsion is added to a beaker. Under ice bath conditions, quinoa polyphenols and deionized water are added to the beaker. A magnetic stirrer is used to set a constant temperature stirring at 150 r / min for 15 h. The resulting product is added to a centrifuge. The centrifuge is set to centrifuge at 9000 r / min for 18 min. A precipitate is obtained from the centrifuged product. The precipitate is washed alternately with deionized water and ethanol. The resulting product is subjected to vacuum drying to obtain particulate matter. The particulate matter and aminomethane buffer solution are mixed and set to ultrasonic treatment at 250 W for 25 min. The resulting product is added to a mixer. Dopamine hydrochloride is added to the mixer. The mixer is set to stir at 350 r / min for 25 min. The resulting product is added to a centrifuge. The centrifuge is set to centrifuge at 7000 r / min for 8 min. A solid is obtained by centrifugation. The solid is washed with deionized water. The resulting product is subjected to vacuum drying to obtain the additive. Among them, the mass ratio of 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, and deionized water is 1:0.5:50. The mass of quinoa polyphenols is 2.5 times the mass of 3,4-ethylenedioxythiophene. The mass ratio of quinoa polyphenols to deionized water is 1:4. The mass of aminomethane buffer solution is 30% of the mass of the particulate matter. The mass of dopamine hydrochloride is 10% of the mass of the particulate matter; S3: Mixing treatment. The mixture and the additive are mixed to complete the mixing treatment and obtain the crude material; The method for the mixing treatment is as follows: After the mixture and the additive are mixed, ball milling treatment is carried out. The ball milling treatment time is 13 h. Then it is sent into an oven. The oven is set to dry at 90 °C for 5 h to complete the mixing treatment and obtain the crude material. Among them, the mass ratio of the mixture to the additive is 1:0.25; S4: Carbonization treatment. The crude material is carbonized to obtain the base material; The method for the carbonization treatment is as follows: The crude material is sent into a carbonization furnace. The heating rate is set to 4 °C / min and heated to 500 °C, and held for 50 min. Then the heating rate is set to 15 °C / min and heated to 900 °C, and held for 7 h to complete the carbonization treatment and obtain the base material; S5: Graphitization treatment. The base material is graphitized to obtain the silicon-carbon negative electrode material; The method for the graphitization treatment is as follows: The heating rate is set to 35 °C / min and heated to 2900 °C, and held for 8 h to complete the graphitization treatment and obtain the silicon-carbon negative electrode material.

[0024] Example three:

[0025] S1: Mixing material preparation. The raw materials of the mixing material include graphene oxide, silicon nanoparticles, graphite, conductive carbon black, and phenolic resin. The raw materials are mixed to obtain the mixing material. Among them, the mass ratio of each raw material is 1:3:1:0.4:0.2; S2: Additive preparation. The raw materials of the additive include quinoa polyphenols, 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, deionized water, aminomethane buffer solution, and dopamine hydrochloride; The quinoa polyphenols are prepared by the following method: Select quinoa as the raw material, crush the quinoa, mix the obtained product with petroleum ether, oscillate for 4 h, filter the obtained product by suction and dry it to obtain quinoa powder. The quinoa powder is further processed to obtain quinoa polyphenols. The mass of petroleum ether is 4 times the mass of the crushed quinoa. The particle size of the crushed quinoa is 40 μm. The quinoa powder and the treatment liquid are added to a mixer, and the mixer is set to stir at 300 r / min for 20 min. The obtained product is subjected to ultrasonic microwave extraction treatment. The ultrasonic microwave extraction treatment is set at a temperature of 50 °C, an ultrasonic power of 200 W, a microwave power of 100 Hz, and a treatment time of 40 min. The obtained product is added to a centrifuge, and the centrifuge is set to centrifuge at 6000 r / min for 10 min. The supernatant is obtained from the centrifuged product. After the supernatant is mixed with PBS buffer solution, it is freeze-dried to obtain quinoa polyphenols. Among them, the mass of the treatment liquid is 8 times the mass of the quinoa powder, and the mass of the PBS buffer solution is 60% of the mass of the supernatant; The treatment liquid is prepared by the following method: Ethanol, deionized water, 1-ethyl-3-methylimidazolium tetrafluoroborate, and ferric chloride are added to a mixer, and the mixer is set to stir at 400 r / min for 30 min to obtain the treatment liquid. Among them, the particle size of ferric chloride is 10 nm, and the mass ratio of ethanol, deionized water, 1-ethyl-3-methylimidazolium tetrafluoroborate, and ferric chloride is 1:1.2:0.12:0.2; The method for preparing the additive is as follows: 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, and deionized water are added to a mixer. The mixer is set to stir at 120 r / min for 20 min. The resulting product is subjected to ultrasonic treatment to obtain an emulsion. The emulsion is added to a beaker. Under ice bath conditions, quinoa polyphenols and deionized water are added to the beaker. A magnetic stirrer is used to set a constant temperature stirring at 200 r / min for 20 h. The resulting product is added to a centrifuge. The centrifuge is set to centrifuge at 10,000 r / min for 20 min. A precipitate is obtained from the centrifuged product. The precipitate is washed alternately with deionized water and ethanol. The resulting product is subjected to vacuum drying to obtain particulate matter. The particulate matter and aminomethane buffer solution are mixed and set to ultrasonic treatment at 300 W for 30 min. The resulting product is added to a mixer. Dopamine hydrochloride is added to the mixer. The mixer is set to stir at 400 r / min for 30 min. The resulting product is added to a centrifuge. The centrifuge is set to centrifuge at 8,000 r / min for 10 min. A solid is obtained from the centrifugation treatment. The solid is washed with deionized water. The resulting product is subjected to vacuum drying to obtain the additive. Among them, the mass ratio of 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, and deionized water is 1:0.6:60. The mass of quinoa polyphenols is 3 times the mass of 3,4-ethylenedioxythiophene. The mass ratio of quinoa polyphenols to deionized water is 1:5. The mass of aminomethane buffer solution is 40 times the mass of the particulate matter. The mass of dopamine hydrochloride is 12% of the mass of the particulate matter; S3: Mixing treatment. The mixture and the additive are mixed to complete the mixing treatment and obtain the crude material; The method for the mixing treatment is as follows: After the mixture and the additive are mixed, ball milling treatment is carried out. The ball milling treatment time is 16 h. Then it is sent into an oven. The oven is set to dry at 100 °C for 6 h to complete the mixing treatment and obtain the crude material. Among them, the mass ratio of the mixture to the additive is 1:0.3; S4: Carbonization treatment. The crude material is carbonized to obtain the base material; The method for the carbonization treatment is as follows: The crude material is sent into a carbonization furnace. The heating rate is set to 6 °C / min and heated to 600 °C, and held for 60 min. Then the heating rate is set to 20 °C / min and heated to 1000 °C, and held for 8 h to complete the carbonization treatment and obtain the base material; S5: Graphitization treatment. The base material is graphitized to obtain the silicon-carbon negative electrode material; The method for the graphitization treatment is as follows: The heating rate is set to 40 °C / min and heated to 3000 °C, and held for 10 h to complete the graphitization treatment and obtain the silicon-carbon negative electrode material.

[0026] Comparative Example 1. The difference between this comparative example and Example 1 is that this comparative example does not contain 1-ethyl-3-methylimidazolium tetrafluoroborate.

[0027] Comparative Example 2: The difference between this comparative example and Example 1 is that this comparative example does not contain quinoa polyphenols.

[0028] Comparative Example 3: The difference between this comparative example and Example 1 is that in this comparative example, an equal amount of asphalt is selected to replace phenolic resin.

[0029] Comparative Example 4: The difference between this comparative example and Example 1 is that this comparative example does not contain additives.

[0030] Performance test: The silicon-carbon anode materials prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 were subjected to performance tests, and the obtained test data were recorded in the following table:

[0031] In the performance test, a constant current and constant voltage (CC-CV) mode was used for charge and discharge tests, the test current was set at 0.1C, and the first charge and discharge capacities and the first Coulombic efficiencies of each sample were recorded.

[0032] It can be seen that the first charge and discharge capacities and the first Coulombic efficiencies of the silicon-carbon anode materials prepared in Comparative Examples 1, 2, 3 and 4 are all lower than those in Examples 1, 2 and 3; this shows that: in the preparation process of the silicon-carbon anode material, through further mixing treatment of the mixture, by adding additives during the mixing treatment, quinoa polyphenols and 3,4-ethylenedioxythiophene generate conductive polymers through polymerization reaction, and this conductive polymer can cooperate with the carbon-based material to generate a three-dimensional conductive network, enhancing the electron transport efficiency in the anode material. At the same time, dopamine hydrochloride can generate polydopamine in an aminomethane buffer solution, and the functional groups in quinoa polyphenols and polydopamine react with lithium ions preferentially in the first cycle to form a stable SEI film structure, effectively improving the use performance of the silicon-carbon anode material; In the preparation process of quinoa polyphenols, through the synergistic extraction of ultrasound and microwave, the extraction time can be shortened and the release of polyphenols can be improved. Using the good solubility and conductivity of 1-ethyl-3-methylimidazolium tetrafluoroborate, after mixing with ethanol as the extraction solvent, the chelating ability of polyphenols can form conductive metal complexes, and ferric chloride can generate conductive nanoparticles after carbonization treatment, improving the overall conductivity of the silicon-carbon anode material.

[0033] By comparing and analyzing the relevant data in the table, it can be known that the silicon-carbon anode material prepared by the present invention not only has a good first charge and discharge capacity, but also has an excellent first Coulombic efficiency. This shows that the preparation method of the silicon-carbon anode material provided by the present invention has a broader market prospect and is more suitable for popularization.

[0034] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

[0035] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A method for preparing a silicon-carbon anode material, characterized in that: It includes the following steps: S1: Preparation of the mixture. The raw materials of the mixture include graphene oxide, silicon nanoparticles, graphite, conductive carbon black, and phenolic resin. The raw materials are mixed to obtain the mixture. Among them, the mass ratio of each raw material is 1:(2 - 3):1:(0.2 - 0.4):(0.1 - 0.2); S2: Preparation of the additive. The raw materials of the additive include quinoa polyphenols, 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, deionized water, aminomethane buffer solution, and dopamine hydrochloride; S3: Mixing treatment. The mixture and the additive are mixed to complete the mixing treatment and obtain the crude material; S4: Carbonization treatment. The crude material is carbonized to obtain the base material; S5: Graphitization treatment. The base material is graphitized to obtain the silicon-carbon negative electrode material.

2. The preparation method of the silicon-carbon anode material according to claim 1, wherein, The quinoa polyphenols are prepared by the following method: Select quinoa as the raw material. The quinoa is crushed. The obtained product is mixed with petroleum ether and oscillated for 2 - 4 h. The obtained product is filtered and dried to obtain quinoa powder. The quinoa powder is further processed to obtain quinoa polyphenols.

3. The method for preparing the silicon-carbon anode material according to claim 2, characterized in that, The mass of petroleum ether is 3 - 4 times the mass of the crushed quinoa, and the particle size of the crushed quinoa is 10 - 40 μm.

4. The preparation method of the silicon-carbon anode material according to claim 2, characterized in that, The further processing method of the quinoa powder is: The quinoa powder and the treatment solution are added to a mixer. The mixer is set to stir at 200 - 300 r / min for 10 - 20 min. The obtained product is subjected to ultrasonic microwave extraction treatment. The ultrasonic microwave extraction treatment is set at a temperature of 40 - 50 °C, an ultrasonic power of 100 - 200 W, a microwave power of 80 - 100 Hz, and a treatment time of 30 - 40 min. The obtained product is added to a centrifuge. The centrifuge is set to centrifuge at 4000 - 6000 r / min for 6 - 10 min. The supernatant is obtained from the centrifuged product. After the supernatant is mixed with PBS buffer solution, it is freeze-dried to obtain quinoa polyphenols. Among them, the mass of the treatment solution is 6 - 8 times the mass of the quinoa powder, and the mass of the PBS buffer solution is 40 - 60% of the mass of the supernatant.

5. The preparation method of the silicon-carbon anode material according to claim 4, characterized in that The treatment solution is prepared by the following method: Ethanol, deionized water, 1-ethyl-3-methylimidazolium tetrafluoroborate, and iron chloride are added to a mixer. The mixer is set to stir at 300 - 400 r / min for 20 - 30 min to obtain the treatment solution. Among them, the particle size of iron chloride is 2 - 10 nm, and the mass ratio of ethanol, deionized water, 1-ethyl-3-methylimidazolium tetrafluoroborate, and iron chloride is 1:1.2:(0.8 - 0.12):(0.1 - 0.2).

6. The method for preparing the silicon-carbon anode material according to claim 1, characterized in that The method for preparing the additive is as follows: 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, and deionized water are added to a mixer. The mixer is set to stir at 80-120 r / min for 10-20 min. The resulting product is subjected to ultrasonic treatment to obtain an emulsion. The emulsion is added to a beaker. Under ice bath conditions, quinoa polyphenols and deionized water are added to the beaker. A magnetic stirrer is used to set a constant temperature stirring at 100-200 r / min for 10-20 h. The resulting product is added to a centrifuge. The centrifuge is set to centrifuge at 8000-10000 r / min for 16-20 min. A precipitate is obtained from the centrifuged product. The precipitate is washed alternately with deionized water and ethanol. The resulting product is subjected to vacuum drying to obtain particulate matter. The particulate matter and aminomethane buffer solution are mixed and set to be ultrasonically treated at 200-300 W for 20-30 min. The resulting product is added to a mixer. Dopamine hydrochloride is added to the mixer. The mixer is set to stir at 300-400 r / min for 20-30 min. The resulting product is added to a centrifuge. The centrifuge is set to centrifuge at 6000-8000 r / min for 6-10 min. A solid is obtained from the centrifugation treatment. The solid is washed with deionized water. The resulting product is subjected to vacuum drying to obtain the additive.

7. The method for preparing the silicon-carbon anode material according to claim 6, wherein The mass ratio of 3,4-ethylenedioxythiophene, sodium dodecyl sulfate, and deionized water is 1:(0.4-0.6):(40-60). The mass of quinoa polyphenols is 2-3 times the mass of 3,4-ethylenedioxythiophene. The mass ratio of quinoa polyphenols to deionized water is 1:(3-5). The mass of aminomethane buffer solution is 20-40 times the mass of the particulate matter. The mass of dopamine hydrochloride is 8-12% of the mass of the particulate matter.

8. The method for preparing the silicon-carbon negative electrode material according to claim 1, wherein, The method for the mixing treatment is as follows: The mixture and the additive are mixed and then subjected to ball milling for 10-16 h. Then it is sent to an oven. The oven is set to dry at 80-100 °C for 4-6 h to complete the mixing treatment and obtain the crude material. Among them, the mass ratio of the mixture to the additive is 1:(0.2-0.3).

9. The method for preparing the silicon-carbon anode material according to claim 1, wherein The method for the carbonization treatment is as follows: The crude material is sent into a carbonization furnace. The heating rate is set to 2-6 °C / min and heated to 400-600 °C, and kept warm for 40-60 min. Then the heating rate is set to 10-20 °C / min and heated to 800-1000 °C, and kept warm for 6-8 h to complete the carbonization treatment and obtain the base material.

10. The method for preparing the silicon-carbon anode material according to claim 1, wherein The method for the graphitization treatment is as follows: The heating rate is set to 30-40 °C / min and heated to 2800-3000 °C, and kept warm for 6-10 h to complete the graphitization treatment and obtain the silicon-carbon anode material.

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