A method for preparing silicon-carbon negative electrode material

Abstract

The present invention relates to the technical field of silicon-carbon negative electrode materials, and specifically to a method for preparing silicon-carbon negative electrode materials: comprising the following steps: S1: preparing a mixture, wherein the raw materials of the mixture include graphene oxide, silicon nanoparticles, graphite, conductive carbon black, and phenolic resin, and the raw materials are mixed to prepare a mixture, wherein the mass ratio of the raw materials is 1: (2-3): 1: (0.2-0.4): (0.1-0.2). In the present invention, quinoa polyphenols and 3,4-ethylenedioxythiophene are polymerized to generate a conductive polymer, which can synergistically generate a three-dimensional conductive network with a carbon-based material to improve the electron transfer efficiency in the negative electrode material. At the same time, dopamine hydrochloride can generate polydopamine in an aminomethane buffer solution. The functional groups in quinoa polyphenols and polydopamine preferentially react with lithium ions in the first cycle to form a stable SEI film structure, effectively improving the performance of the silicon-carbon negative electrode material.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon-carbon negative electrode materials, and in particular to a method for preparing a silicon-carbon negative electrode material. Background Art

[0002] Silicon-carbon negative electrode material is a new type of lithium battery negative electrode material, which is composed of silicon and carbon. It combines the advantages of silicon's high specific capacity with carbon's good conductivity and cycle stability. It can make up for the defects of single silicon material's large volume expansion and poor conductivity, and has significant potential in new energy vehicles, energy storage and other fields.

[0003] In the prior art, the preparation of silicon-carbon anode materials requires a high-temperature carbonization process. This high temperature affects the pore structure of the silicon-carbon anode material, affecting the lithium ion transmission efficiency and thus the conductivity of the silicon-carbon anode material. Based on this, the present invention provides a method for preparing a silicon-carbon anode material. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a silicon-carbon negative electrode material. The silicon-carbon negative electrode material prepared by the present invention not only has a good first charge and discharge capacity, but also has an excellent first coulombic efficiency, which effectively improves the performance of the silicon-carbon negative electrode material.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing a silicon-carbon negative electrode material comprises the following steps:

[0007] S1: preparing a mixture, wherein the raw materials of the mixture include graphene oxide, silicon nanoparticles, graphite, conductive carbon black, and phenolic resin, and the raw materials are mixed to prepare a mixture, wherein the mass ratio of the raw materials is 1:(2-3):1:(0.2-0.4):(0.1-0.2);

[0008] S2: Preparation of additives, wherein the raw materials of the additives include quinoa polyphenols, 3,4-ethylenedioxythiophene, sodium lauryl sulfate, deionized water, aminomethane buffer, and dopamine hydrochloride;

[0009] S3: Mixing process, mixing the mixed material and the additive, completing the mixing process to obtain a coarse material;

[0010] S4: carbonization treatment, carbonizing the coarse material to obtain the base material;

[0011] S5: Graphitization treatment: graphitizing the base material to obtain a silicon-carbon negative electrode material.

[0012] Furthermore, the quinoa polyphenols are prepared by the following method: quinoa is selected as a raw material, the quinoa is crushed, the obtained product is mixed with petroleum ether, and the mixture is shaken for 2 to 4 hours, the obtained product is filtered and dried to obtain quinoa powder, and the quinoa powder is further processed to obtain quinoa polyphenols.

[0013] Furthermore, the mass of petroleum ether is 3 to 4 times the mass of the crushed quinoa, and the particle size of the crushed quinoa is 10 to 40 μm.

[0014] Furthermore, the method for further processing quinoa powder is as follows: quinoa powder and treatment liquid are added to a mixer, the mixer is set to 200-300 r / min and stirred for 10-20 minutes, 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 minutes, the obtained product is added to a centrifuge, the centrifuge is set to 4000-6000 r / min and centrifuged for 6-10 minutes, a supernatant is obtained from the product obtained by centrifugation, the supernatant is mixed with PBS buffer, and then freeze-dried to obtain quinoa polyphenols, wherein the mass of the treatment liquid is 6-8 times the mass of the quinoa powder, and the mass of the PBS buffer is 40-60% of the mass of the supernatant.

[0015] Furthermore, 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 300-400 r / min and stirred for 20-30 minutes to prepare the treatment liquid, wherein the particle size of the 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).

[0016] Furthermore, the method for preparing the additive is as follows: 3,4-ethylenedioxythiophene, sodium lauryl sulfate, and deionized water are added to a mixer, the mixer is set to 80-120 r / min and stirred for 10-20 min, the obtained product is ultrasonically treated to prepare an emulsion, the emulsion is added to a beaker, quinoa polyphenols and deionized water are added to the beaker under ice bath conditions, a magnetic stirrer is set to 100-200 r / min and stirred at a constant temperature for 10-20 h, the obtained product is added to a centrifuge, the centrifuge is set to 8000-10000 r / min and centrifuged for 16-20 min, a precipitate is obtained from the product obtained by centrifugation, and the precipitate is precipitated. The precipitate is washed alternately with deionized water and ethanol, the obtained product is vacuum dried to obtain granules, the granules are mixed with aminomethane buffer, and ultrasonic treatment is set at 200-300W for 20-30min, the obtained product is added to a mixer, dopamine hydrochloride is added to the mixer, the mixer is set at 300-400r / min for stirring for 20-30min, the obtained product is added to a centrifuge, the centrifuge is set at 6000-8000r / min for centrifugation for 6-10min, solids are obtained by centrifugation, the solids are washed with deionized water, and the obtained product is vacuum dried to obtain an additive.

[0017] Furthermore, 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 and deionized water is 1:(3-5), the mass of aminomethane buffer 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.

[0018] Furthermore, the mixing method is as follows: the mixture and the additive are mixed and then ball milled for 10 to 16 hours, and then sent to an oven, and the oven is set at 80 to 100° C. for drying for 4 to 6 hours to complete the mixing process and obtain a coarse material, wherein the mass ratio of the mixture to the additive is 1: (0.2 to 0.3).

[0019] Furthermore, the carbonization treatment method is as follows: the coarse material is fed into the carbonization furnace, the heating rate is set to 2-6°C / min, the temperature is raised to 400-600°C, and the temperature is kept warm for 40-60 minutes, and then the heating rate is set to 10-20°C / min, the temperature is raised to 800-1000°C, and the temperature is kept warm for 6-8 hours to complete the carbonization treatment and obtain the base material.

[0020] Furthermore, the graphitization treatment method is: setting the heating rate to 30-40°C / min, heating to 2800-3000°C, keeping the temperature for 6-10 hours, completing the graphitization treatment, and preparing the silicon-carbon negative electrode material.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. In the present invention, during the preparation process of the silicon-carbon negative electrode material, the mixture is further mixed and additives are added during the mixing process. Quinoa polyphenols and 3,4-ethylenedioxythiophene generate a conductive polymer through a polymerization reaction. The conductive polymer can cooperate with the carbon-based material to generate a three-dimensional conductive network, thereby enhancing the electron transfer efficiency in the negative electrode material. At the same time, dopamine hydrochloride can generate polydopamine in an aminomethane buffer solution. The functional groups in quinoa polyphenols and polydopamine preferentially react with lithium ions in the first cycle to form a stable SEI film structure, thereby effectively improving the performance of the silicon-carbon negative electrode material.

[0023] 2. In the present invention, during the preparation process of quinoa polyphenols, the extraction time can be shortened and the release of polyphenols can be improved through the synergistic extraction of ultrasound and microwaves. The good solubility and conductivity of 1-ethyl-3-methylimidazolium tetrafluoroborate is used as an extraction solvent after being mixed with ethanol. The chelating ability of polyphenols can be used to form a conductive metal complex. Ferric chloride can generate conductive nanoparticles after carbonization treatment, thereby improving the overall conductivity of the silicon-carbon negative electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A flow chart of a method for preparing silicon-carbon negative electrode materials is proposed for the invention. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] It should be noted that the raw materials used in the following examples are all commercially available raw materials.

[0027] Example 1:

[0028] S1: preparing a mixture, wherein the raw materials of the mixture include graphene oxide, silicon nanoparticles, graphite, conductive carbon black, and phenolic resin, and the raw materials are mixed to prepare a mixture, wherein the mass ratio of the raw materials is 1:2:1:0.2:0.1;

[0029] S2: Preparation of additives, the raw materials of the additives include quinoa polyphenols, 3,4-ethylenedioxythiophene, sodium lauryl sulfate, deionized water, aminomethane buffer, and dopamine hydrochloride;

[0030] Quinoa polyphenols are prepared by the following method: quinoa is selected as a raw material, the quinoa is crushed, the obtained product is mixed with petroleum ether, and shaken for 2 hours. The obtained product is filtered and dried to obtain quinoa powder, and 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 processing liquid are added to a mixer, the mixer is set to 200 r / min and stirred for 10 minutes, the obtained product is subjected to ultrasonic microwave extraction, 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 processing time of 30 minutes, the obtained product is added to a centrifuge, the centrifuge is set at 4000 r / min and centrifuged for 6 minutes, a supernatant is obtained from the centrifuged product, the supernatant is mixed with PBS buffer, and then freeze-dried to obtain quinoa polyphenols, wherein the mass of the processing liquid is 6 times the mass of the quinoa powder, and the mass of the PBS buffer is 40% of the mass of the supernatant;

[0031] 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 300 r / min and stirred for 20 minutes to prepare the treatment liquid, wherein the particle size of the 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;

[0032] The method for preparing the additive is as follows: 3,4-ethylenedioxythiophene, sodium lauryl sulfate, and deionized water are added to a mixer, the mixer is set to 80 r / min and stirred for 10 minutes, the obtained product is ultrasonically treated to obtain an emulsion, the emulsion is added to a beaker, quinoa polyphenols and deionized water are added to the beaker under ice bath conditions, a magnetic stirrer is set to 100 r / min and stirred at a constant temperature for 10 hours, the obtained product is added to a centrifuge, the centrifuge is set to 8000 r / min and centrifuged for 16 minutes, a precipitate is obtained from the product obtained by centrifugation, the precipitate is alternately washed with deionized water and ethanol, the obtained product is vacuum dried to obtain particles, the particles are mixed with aminomethane buffer and ultrasonically treated at 200W for 20 min, the resulting product is added to a mixer, dopamine hydrochloride is added to the mixer, the mixer is set to 300 r / min and stirred for 20 min, the resulting product is added to a centrifuge, the centrifuge is set to 6000 r / min and centrifuged for 6 min, solids are obtained by centrifugation, the solids are washed with deionized water, and the resulting product is vacuum dried to prepare an additive, wherein the mass ratio of 3,4-ethylenedioxythiophene, sodium lauryl sulfate, and deionized water is 1:0.4:40, the mass of quinoa polyphenols is 2 times the mass of 3,4-ethylenedioxythiophene, the mass ratio of quinoa polyphenols to deionized water is 1:3, the mass of aminomethane buffer is 20 times the mass of particulate matter, and the mass of dopamine hydrochloride is 8% of the mass of particulate matter;

[0033] S3: Mixing process, mixing the mixed material and the additive, completing the mixing process to obtain a coarse material;

[0034] The mixing method is as follows: the mixed material and the additive are mixed and then ball milled for 10 hours, and then placed in an oven and dried at 80° C. for 4 hours to complete the mixing process and obtain a coarse material, wherein the mass ratio of the mixed material to the additive is 1:0.2;

[0035] S4: carbonization treatment, carbonizing the coarse material to obtain the base material;

[0036] The carbonization treatment method is as follows: the coarse material is fed into the carbonization furnace, the heating rate is set to 2°C / min, the temperature is raised to 400°C, and the temperature is kept for 40 minutes, then the heating rate is set to 10°C / min, the temperature is raised to 800°C, and the temperature is kept for 6 hours to complete the carbonization treatment and obtain the base material;

[0037] S5: Graphitization treatment, graphitizing the base material to obtain a silicon-carbon negative electrode material;

[0038] The graphitization treatment method is: setting the heating rate to 30°C / min, heating to 2800°C, and keeping the temperature for 6 hours to complete the graphitization treatment and obtain the silicon-carbon negative electrode material.

[0039] Example 2:

[0040] S1: preparing a mixture, wherein the raw materials of the mixture include graphene oxide, silicon nanoparticles, graphite, conductive carbon black, and phenolic resin, and the raw materials are mixed to prepare a mixture, wherein the mass ratio of the raw materials is 1:2.5:1:0.3:0.15;

[0041] S2: Preparation of additives, the raw materials of the additives include quinoa polyphenols, 3,4-ethylenedioxythiophene, sodium lauryl sulfate, deionized water, aminomethane buffer, and dopamine hydrochloride;

[0042] Quinoa polyphenols are prepared by the following method: quinoa is selected as a raw material, the quinoa is crushed, the obtained product is mixed with petroleum ether, and shaken for 3 hours. The obtained product is filtered and dried to obtain quinoa powder, and 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 processing liquid are added to a mixer, the mixer is set to 250 r / min and stirred for 15 minutes, the obtained product is subjected to ultrasonic microwave extraction, the ultrasonic microwave extraction treatment is set at a temperature of 45° C., the ultrasonic power is 150 W, the microwave power is 90 Hz, and the processing time is 35 minutes, the obtained product is added to a centrifuge, the centrifuge is set at 5000 r / min and centrifuged for 8 minutes, a supernatant is obtained from the centrifuged product, the supernatant is mixed with PBS buffer, and then freeze-dried to obtain quinoa polyphenols, wherein the mass of the processing liquid is 7 times the mass of the quinoa powder, and the mass of the PBS buffer is 50% of the mass of the supernatant;

[0043] 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 at 350 r / min and stirred for 25 minutes to prepare the treatment liquid, wherein the particle size of the 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;

[0044] The method for preparing the additive is as follows: 3,4-ethylenedioxythiophene, sodium lauryl sulfate, and deionized water are added to a mixer, the mixer is set to 100 r / min and stirred for 15 minutes, the obtained product is ultrasonically treated to obtain an emulsion, the emulsion is added to a beaker, quinoa polyphenols and deionized water are added to the beaker under ice bath conditions, a magnetic stirrer is set to 150 r / min and stirred at a constant temperature for 15 hours, the obtained product is added to a centrifuge, the centrifuge is set to 9000 r / min and centrifuged for 18 minutes, a precipitate is obtained from the product obtained by centrifugation, the precipitate is alternately washed with deionized water and ethanol, the obtained product is vacuum dried to obtain particles, the particles are mixed with aminomethane buffer and ultrasonically treated at 250W for 25 min, the resulting product is added to a mixer, dopamine hydrochloride is added to the mixer, the mixer is set to 350 r / min and stirred for 25 min, the resulting product is added to a centrifuge, the centrifuge is set to 7000 r / min and centrifuged for 8 min, solids are obtained by centrifugation, the solids are washed with deionized water, and the resulting product is vacuum dried to prepare an additive, wherein the mass ratio of 3,4-ethylenedioxythiophene, sodium lauryl 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 is 30% of the mass of the particulate matter, and the mass of dopamine hydrochloride is 10% of the mass of the particulate matter;

[0045] S3: Mixing process, mixing the mixed material and the additive, completing the mixing process to obtain a coarse material;

[0046] The mixing method is as follows: the mixed material and the additive are mixed and then ball milled for 13 hours, and then placed in an oven and dried at 90° C. for 5 hours to complete the mixing process and obtain a coarse material, wherein the mass ratio of the mixed material to the additive is 1:0.25;

[0047] S4: carbonization treatment, carbonizing the coarse material to obtain the base material;

[0048] The carbonization treatment method is as follows: the coarse material is fed into the carbonization furnace, the heating rate is set to 4°C / min, the temperature is raised to 500°C, and the temperature is kept for 50 minutes, then the heating rate is set to 15°C / min, the temperature is raised to 900°C, and the temperature is kept for 7 hours to complete the carbonization treatment and obtain the base material;

[0049] S5: Graphitization treatment, graphitizing the base material to obtain a silicon-carbon negative electrode material;

[0050] The graphitization treatment method is: setting the heating rate to 35°C / min, heating to 2900°C, and keeping the temperature for 8 hours to complete the graphitization treatment and obtain the silicon-carbon negative electrode material.

[0051] Example 3:

[0052] S1: preparing a mixture, wherein the raw materials of the mixture include graphene oxide, silicon nanoparticles, graphite, conductive carbon black, and phenolic resin, and the raw materials are mixed to prepare a mixture, wherein the mass ratio of the raw materials is 1:3:1:0.4:0.2;

[0053] S2: Preparation of additives, the raw materials of the additives include quinoa polyphenols, 3,4-ethylenedioxythiophene, sodium lauryl sulfate, deionized water, aminomethane buffer, and dopamine hydrochloride;

[0054] Quinoa polyphenols are prepared by the following method: quinoa is selected as a raw material, the quinoa is crushed, the obtained product is mixed with petroleum ether, and shaken for 4 hours. The obtained product is filtered and dried to obtain quinoa powder, and 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 processing liquid are added to a mixer, the mixer is set to 300 r / min and stirred for 20 minutes, the obtained product is subjected to ultrasonic microwave extraction, 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 processing time of 40 minutes, the obtained product is added to a centrifuge, the centrifuge is set to 6000 r / min and centrifuged for 10 minutes, a supernatant is obtained from the centrifuged product, the supernatant is mixed with PBS buffer, and then freeze-dried to obtain quinoa polyphenols, wherein the mass of the processing liquid is 8 times the mass of the quinoa powder, and the mass of the PBS buffer is 60% of the mass of the supernatant;

[0055] 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 400 r / min and stirred for 30 minutes to prepare the treatment liquid, wherein the particle size of the 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;

[0056] The method for preparing the additive is as follows: 3,4-ethylenedioxythiophene, sodium lauryl sulfate, and deionized water are added to a mixer, the mixer is set at 120 r / min and stirred for 20 minutes, the obtained product is ultrasonically treated to obtain an emulsion, the emulsion is added to a beaker, quinoa polyphenols and deionized water are added to the beaker under ice bath conditions, a magnetic stirrer is set at 200 r / min and stirred at a constant temperature for 20 hours, the obtained product is added to a centrifuge, the centrifuge is set at 10000 r / min and centrifuged for 20 minutes, a precipitate is obtained from the product obtained by centrifugation, the precipitate is alternately washed with deionized water and ethanol, the obtained product is vacuum dried to obtain particles, the particles are mixed with aminomethane buffer and ultrasonically treated at 300W for 30 min, the resulting product is added to a mixer, dopamine hydrochloride is added to the mixer, the mixer is set to 400 r / min and stirred for 30 min, the resulting product is added to a centrifuge, the centrifuge is set to 8000 r / min and centrifuged for 10 min, solids are obtained by centrifugation, the solids are washed with deionized water, and the resulting product is vacuum dried to prepare an additive, wherein the mass ratio of 3,4-ethylenedioxythiophene, sodium lauryl 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 is 40 times the mass of particulate matter, and the mass of dopamine hydrochloride is 12% of the mass of particulate matter;

[0057] S3: Mixing process, mixing the mixed material and the additive, completing the mixing process to obtain a coarse material;

[0058] The mixing method is as follows: the mixed material and the additive are mixed and then ball milled for 16 hours, and then placed in an oven and dried at 100° C. for 6 hours to complete the mixing process and obtain a coarse material, wherein the mass ratio of the mixed material to the additive is 1:0.3;

[0059] S4: carbonization treatment, carbonizing the coarse material to obtain the base material;

[0060] The carbonization treatment method is as follows: the coarse material is fed into the carbonization furnace, the heating rate is set to 6°C / min, the temperature is raised to 600°C, and the temperature is kept for 60 minutes, then the heating rate is set to 20°C / min, the temperature is raised to 1000°C, and the temperature is kept for 8 hours to complete the carbonization treatment and obtain the base material;

[0061] S5: Graphitization treatment, graphitizing the base material to obtain a silicon-carbon negative electrode material;

[0062] The graphitization treatment method is: setting the heating rate to 40°C / min, heating to 3000°C, and keeping the temperature for 10 hours to complete the graphitization treatment and obtain the silicon-carbon negative electrode material.

[0063] 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.

[0064] Comparative Example 2: The difference between this comparative example and Example 1 is that this comparative example does not contain quinoa polyphenols.

[0065] Comparative Example 3: The difference between this comparative example and Example 1 is that an equal amount of asphalt is used to replace the phenolic resin in this comparative example.

[0066] Comparative Example 4: This comparative example is different from Example 1 in that: this comparative example does not contain any additives.

[0067] Performance test: The silicon-carbon negative electrode 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 test data obtained are recorded in the following table:

[0068]

[0069] In the performance test, the constant current constant voltage (CC-CV) mode was used for charge and discharge tests. The test current was set to 0.1C, and the first charge and discharge capacity and first coulombic efficiency of each sample were recorded.

[0070] It can be seen that the first charge and discharge capacity and the first coulombic efficiency of the silicon-carbon negative electrode materials prepared in Comparative Examples 1, 2, 3, and 4 are lower than those in Examples 1, 2, and 3; this shows that: in the preparation process of the silicon-carbon negative electrode material, by further mixing the mixture and adding additives during the mixing process, quinoa polyphenols and 3,4-ethylenedioxythiophene are polymerized to form a conductive polymer, and the conductive polymer can cooperate with the carbon-based material to form a three-dimensional conductive network, thereby enhancing the electron transfer efficiency in the negative electrode material. At the same time, dopamine hydrochloride can generate polydopamine in the aminomethane buffer solution, and the functional groups in quinoa polyphenols and polydopamine preferentially react with lithium ions in the first cycle to form a stable SEI film structure, thereby effectively improving the performance of the silicon-carbon negative electrode material;

[0071] During the preparation of quinoa polyphenols, the synergistic extraction of ultrasound and microwaves can shorten the extraction time and increase the release of polyphenols. The good solubility and conductivity of 1-ethyl-3-methylimidazolium tetrafluoroborate is mixed with ethanol as an extraction solvent. The chelating ability of polyphenols can form a conductive metal complex. Ferric chloride can generate conductive nanoparticles after carbonization treatment, thereby improving the overall conductivity of the silicon-carbon negative electrode material.

[0072] Comparing and analyzing the relevant data in the table shows that the silicon-carbon anode material prepared by the present invention not only has a good initial charge and discharge capacity, but also has an excellent initial coulombic efficiency. This shows that the method for preparing the silicon-carbon anode material provided by the present invention has a broader market prospect and is more suitable for promotion.

[0073] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0074] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a silicon-carbon negative electrode material, characterized in that: The following steps are involved: S1: preparing a mixture, wherein the raw materials of the mixture include graphene oxide, silicon nanoparticles, graphite, conductive carbon black, and phenolic resin, and the raw materials are mixed to prepare a mixture, wherein the mass ratio of the raw materials is 1:(2-3):1:(0.2-0.4):(0.1-0.2); S2: Preparation of additives, wherein the raw materials of the additives include quinoa polyphenols, 3,4-ethylenedioxythiophene, sodium lauryl sulfate, deionized water, aminomethane buffer, and dopamine hydrochloride; The quinoa polyphenols are prepared by the following method: quinoa is selected as a raw material, the quinoa is crushed, the obtained product is mixed with petroleum ether, and the mixture is shaken for 2 to 4 hours, the obtained product is filtered and dried to obtain quinoa powder, and the quinoa powder is further processed to obtain quinoa polyphenols; The method for further processing the quinoa powder is as follows: the quinoa powder and the processing liquid are added to a mixer, the mixer is set to 200-300 r / min and stirred for 10-20 minutes, the obtained product is subjected to ultrasonic microwave extraction treatment, the ultrasonic microwave extraction treatment is set at a temperature of 40-50° C., the ultrasonic power is 100-200 W, the microwave power is 80-100 Hz, and the treatment time is 30-40 minutes, the obtained product is added to a centrifuge, the centrifuge is set to 4000-6000 r / min and centrifuged for 6-10 minutes, a supernatant is obtained from the product obtained by centrifugation, the supernatant is mixed with PBS buffer, and then freeze-dried to obtain quinoa polyphenols, wherein the mass of the processing liquid is 6-8 times the mass of the quinoa powder, and the mass of the PBS buffer is 40-60% 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 at 300-400 r / min and stirred for 20-30 minutes to prepare the treatment liquid, wherein the particle size of the 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); Quinoa polyphenols and 3,4-ethylenedioxythiophene are polymerized to form a conductive polymer, while dopamine hydrochloride is reacted in an aminomethane buffer to form polydopamine. S3: Mixing process, mixing the mixed material and the additive, completing the mixing process to obtain a coarse material; S4: carbonization treatment, carbonizing the coarse material to obtain the base material; S5: Graphitization treatment: graphitizing the base material to obtain a silicon-carbon negative electrode material.

2. The method for preparing a silicon-carbon negative electrode material according to claim 1, wherein: The mass of petroleum ether is 3 to 4 times the mass of the crushed quinoa, and the particle size of the crushed quinoa is 10 to 40 μm.

3. The method for preparing a silicon-carbon negative electrode material according to claim 1, wherein: The preparation method of the additive comprises the following steps: adding 3,4-ethylenedioxythiophene, sodium lauryl sulfate and deionized water into a mixer, setting the mixer to 80-120 r / min and stirring for 10-20 min, subjecting the obtained product to ultrasonic treatment to prepare an emulsion, adding the emulsion into a beaker, adding quinoa polyphenols and deionized water into the beaker under ice bath conditions, using a magnetic stirrer set at 100-200 r / min and constant temperature stirring for 10-20 h, adding the obtained product into a centrifuge, setting the centrifuge to 8000-10000 r / min and centrifuging for 16-20 min, obtaining a precipitate from the centrifuged product, and using the precipitate to make a precipitate. The particles are washed alternately with deionized water and ethanol, and the obtained product is vacuum dried to obtain particles. The particles are mixed with aminomethane buffer and ultrasonically treated at 200-300W for 20-30 minutes. The obtained product is added to a mixer, and dopamine hydrochloride is added to the mixer. The mixer is set to 300-400r / min for stirring for 20-30 minutes. The obtained product is added to a centrifuge, and the centrifuge is set to 6000-8000r / min for centrifugation for 6-10 minutes. Solids are obtained by centrifugation, and the solids are washed with deionized water. The obtained product is vacuum dried to obtain an additive.

4. The method for preparing a silicon-carbon negative electrode material according to claim 3, 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 and deionized water is 1: (3-5), the mass of aminomethane buffer is 20-40 times the mass of particulate matter, and the mass of dopamine hydrochloride is 8-12% of the mass of particulate matter.

5. The method for preparing a silicon-carbon negative electrode material according to claim 1, wherein: The mixing method comprises the following steps: the mixed material and the additive are mixed and then ball milled for 10 to 16 hours, and then the mixed material is placed in an oven and dried at 80 to 100° C. for 4 to 6 hours to complete the mixing process and obtain a coarse material, wherein the mass ratio of the mixed material to the additive is 1:(0.2 to 0.3).

6. The method for preparing a silicon-carbon negative electrode material according to claim 1, wherein: The carbonization treatment method is as follows: the coarse material is fed into a carbonization furnace, the heating rate is set to 2-6°C / min, the temperature is raised to 400-600°C, and the temperature is kept warm for 40-60 minutes, then the heating rate is set to 10-20°C / min, the temperature is raised to 800-1000°C, and the temperature is kept warm for 6-8 hours to complete the carbonization treatment and obtain the base material.

7. The method for preparing a silicon-carbon negative electrode material according to claim 1, wherein: The graphitization treatment method is: setting the heating rate to 30-40°C / min, heating to 2800-3000°C, keeping the temperature for 6-10 hours, completing the graphitization treatment, and preparing the silicon-carbon negative electrode material.

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