A lithium battery negative electrode material based on modified biomass carbon material and a preparation method thereof
By combining modified biomass carbon materials with nano-silicon and conductive materials, a stable three-dimensional conductive network was constructed, which solved the structural stability and performance problems of lithium-ion battery anode materials, and achieved high energy density and stable lithium battery performance improvement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DONGGUAN YOUFANG NEW ENERGY TECH CO LTD
- Filing Date
- 2024-12-31
- Publication Date
- 2026-06-09
Smart Images
Figure BDA0005220631040000101 
Figure BDA0005220631040000111
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium battery technology, specifically relating to a lithium battery anode material based on modified biomass carbon materials and its preparation method. Background Technology
[0002] Lithium-ion batteries play a crucial role in the electric vehicle (EV) industry, serving as one of the core components that provides the electricity needed to power vehicles. Therefore, developing advanced lithium-ion batteries with high energy density, high cycle performance, and high stability is essential to meeting the growing demands of next-generation energy storage devices.
[0003] Silicon, as a potential high-performance anode material, is considered a key candidate for next-generation battery technology due to its high theoretical specific capacity. However, silicon faces several major challenges in practical applications: it not only has a low ion diffusion rate and poor conductivity, but also undergoes significant volume changes during lithiation and delithiation, leading to structural damage and rapid capacity degradation. Furthermore, this volume change can trigger the rupture of the solid electrolyte interphase (SEI), further exacerbating capacity decay and reducing the battery's rate performance.
[0004] Existing technologies have made some progress in combining graphene with silicon materials through various methods to improve the electrochemical performance of silicon. However, these approaches still have some shortcomings: the coating effect of graphene on silicon is not ideal, exhibiting poor density and uniformity. Insufficient coating density can lead to direct contact between the electrolyte and silicon, forming a solid electrolyte interphase (SEI) layer, while the non-uniformity of the coating may affect the rate performance of the battery.
[0005] Meanwhile, with the rapid development of my country's industry globally, electric vehicle and electric vehicle manufacturers need to ensure the reliability and performance of batteries under different climatic conditions to meet the needs of the global market. Energy storage systems also need to operate stably in various environments, especially in remote areas or extreme climatic conditions. However, the anode materials in existing technologies cannot meet the increasingly high demands of the global market.
[0006] Therefore, there is an urgent need for a lithium battery anode material based on modified biomass carbon materials and its preparation method. Summary of the Invention
[0007] The purpose of this invention is to provide a lithium battery anode material based on modified biomass carbon materials and its preparation method.
[0008] To achieve the above objectives, the present invention provides the following technical solution:
[0009] This invention provides a method for preparing a lithium battery anode material based on modified biomass carbon materials, comprising the following steps:
[0010] (1) Preparation of modified nano-silicon:
[0011] S1: Mix nano-silicon and deionized water, and ultrasonically disperse at 5°C for 35 min to obtain a nano-silicon dispersion, wherein the concentration of the nano-silicon is 0.15-0.17 g / L;
[0012] S2: 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide were added to the nano-silicon dispersion and stirred evenly at 0-4℃ to obtain a mixture. Ethylenediamine was added to the mixture and reacted at 0-4℃ for 15-17 h. The product was thoroughly washed with acetone / deionized water and dried to obtain modified nano-silicon.
[0013] (2) Under a nitrogen atmosphere, the modified nano-silicon prepared in step (1) is ultrasonically dispersed with thionyl chloride, and N,N-dimethylformamide is added. The temperature is raised to 70-80℃, and the modified conductive material is added. The mixture is reacted at 70-80℃ for 20-25h to obtain a mixture.
[0014] (3) The mixture obtained in step (2) is spray-dried. The inlet temperature of the spray drying is 220-250℃ and the outlet temperature is 120-150℃ to obtain a lithium battery anode material based on modified biomass carbon material.
[0015] Furthermore, the preparation method of the modified conductive material includes the following steps:
[0016] (1) Mix carbon nanotubes, graphene and biomass carbon materials in a mass ratio of (0.3-0.5):1:(1.4-1.6) to obtain a mixture;
[0017] (2) Mix 1 part by weight of fuming sulfuric acid and 95-100 parts by weight of water, stir evenly, then add 30-35 parts by weight of the mixture, stir at 80-85℃ for 3-5 hours, cool to room temperature, filter, and dry to obtain the modified conductive material.
[0018] This invention improves the initial discharge capacity of lithium batteries by amination of nano-silicon and sulfonation of conductive materials. The modified nano-silicon and modified conductive materials react to form a covalent bond, improving the dispersion between the nano-silicon and the conductive material, enhancing the density and uniformity of the coating, thereby increasing the initial discharge capacity of the lithium battery and improving cycle performance at room temperature.
[0019] Further, the preparation method of the biomass carbon material includes the following steps: taking 5 parts by mass of straw and crushing it to less than 40 mesh, mixing it evenly with 10-12 parts by mass of 1-allyl-3-methylimidazolium chloride, stirring at 500-700 rpm for 15-17 h, placing it in a tube furnace for sintering, heating it to 800-830℃ at a heating rate of 3-5℃ / min, maintaining the temperature for 2-3 h, then cooling it to room temperature at a cooling rate of 3-5℃ / min, grinding it into powder, and passing it through a 100-mesh sieve to obtain the biomass carbon material.
[0020] This invention utilizes a modified conductive filler prepared by using a specific ratio of carbon nanotubes, graphene, and biomass carbon materials to improve the high-temperature cycle performance of lithium batteries. Analysis shows that adding a specific ratio of carbon nanotubes, graphene, and biomass carbon materials provides a buffer space for nano-silicon, effectively mitigating its volume expansion during charge and discharge. This buffering effect reduces the pulverization and shedding of electrode materials, maintaining the structural integrity of the electrodes and thus improving the cycle stability of the battery.
[0021] Furthermore, the nano-silicon comprises nano-silicon I, nano-silicon II, and nano-silicon III in a mass ratio of 1:(1.2-1.4):(0.5-0.7); nano-silicon I has an average particle size of 100 nm and a specific surface area of 60 m². 2 / g, model MG-Si-100; average particle size of nano-silicon II 200nm, specific surface area 45m². 2 / g, model MG-Si-200; average particle size of nano-silicon III 1000nm, specific surface area 16m² 2 / g, model MG-Si-1000.
[0022] This invention improves the initial coulombic efficiency of lithium-ion batteries by using nano-silicon with specific parameters and ratios. Because the combination of nano-silicon with different particle sizes and surface areas with carbon nanotubes, graphene, and biomass carbon materials can produce a synergistic effect, using nano-silicon with different particle sizes can optimize the pore structure and density of the electrode material, forming a denser electrode structure, reducing electrolyte penetration, decreasing SEI layer formation consumption, and further improving the initial coulombic efficiency of lithium-ion batteries.
[0023] Furthermore, the carbon nanotubes have an inner diameter of 10-20 nm, a length of 5-15 μm, and a specific surface area of 120-180 m². 2 / g of multi-walled carbon nanotubes.
[0024] Furthermore, the graphene has a thickness of 1-5 nm; a single-layer diameter of 5-45 μm; an electrical conductivity of 100,000 S / m; and a specific surface area of 24 m². 2 / g.
[0025] When the biomass carbon material prepared in this invention is combined with carbon nanotubes and graphene with specific parameters, the cycling performance of lithium battery anode materials at low temperatures can be improved. Under these conditions, the synergistic effect of biomass carbon material, carbon nanotubes, and graphene constructs a stable three-dimensional conductive network, providing a fast transport channel for lithium ions, reducing transport resistance, and improving charge and discharge efficiency.
[0026] Furthermore, the mass ratio of modified nano-silicon to the modified conductive material is (4-7):1.
[0027] Furthermore, the molar ratio of thionyl chloride to modified nano-silicon is (1.5-2.0):1.
[0028] Furthermore, the molar ratio of N,N-dimethylformamide to sulfoxide is (0.1-0.3):1.
[0029] Furthermore, the amount of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride added is 20% to 23% of the mass of nano-silicon; the amount of N-hydroxysuccinimide added is 20% to 23% of the mass of nano-silicon.
[0030] Furthermore, the amount of ethylenediamine added is 3% to 6% of the volume of the mixed liquid.
[0031] This invention provides a lithium battery anode material based on modified biomass carbon material prepared by the aforementioned method.
[0032] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:
[0033] 1. This invention modifies nano-silicon by amination and conductive materials by sulfonation. The modified nano-silicon and the modified conductive materials react and are connected by covalent bonds, which improves the dispersion between nano-silicon and conductive materials, improves the density and uniformity of the coating, thereby improving the initial discharge capacity of lithium batteries and improving the cycle performance at room temperature.
[0034] 2. This invention utilizes a modified conductive filler prepared by using a specific ratio of carbon nanotubes, graphene, and biomass carbon materials. This filler provides a buffer space for nano-silicon, effectively mitigating its volume expansion during charging and discharging. This buffering effect reduces the pulverization and shedding of electrode materials, maintaining the structural integrity of the electrodes and thus improving the high-temperature cycle performance of lithium batteries.
[0035] 3. By using nano-silicon with specific parameters and ratios, the combination of nano-silicon with different particle sizes and surface areas with carbon nanotubes, graphene and biomass carbon materials can produce a synergistic effect. By using nano-silicon with different particle sizes, the pore structure and density of the electrode material can be optimized to form a denser electrode structure, reduce electrolyte penetration, reduce the consumption of SEI layer formation, and improve the first coulombic efficiency of lithium batteries.
[0036] 4. When the biomass carbon material prepared by this invention is compounded with carbon nanotubes and graphene with specific parameters, the synergistic effect of the biomass carbon material, carbon nanotubes and graphene constructs a stable three-dimensional conductive network. Lithium ions provide a fast transport channel, reduce transport resistance, improve charge and discharge efficiency, and can improve the cycle performance of lithium battery anode materials at low temperatures. Detailed Implementation
[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0038] All raw materials used in this invention are commercially available and were purchased from the following manufacturers:
[0039] 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, CAS: 25952-53-8.
[0040] Fuming sulfuric acid, CAS: 8014-95-7, Guangdong Daxiao Chemical Co., Ltd.
[0041] 1-Allyl-3-methylimidazolium chloride, brand Sigma-Aldrich, product number 43961.
[0042] Example 1
[0043] This embodiment provides a method for preparing a lithium battery anode material based on modified biomass carbon material, including the following steps:
[0044] (1) Preparation of modified nano-silicon:
[0045] S1: Mix nano-silicon and deionized water, and ultrasonically disperse at 5°C for 35 min to obtain a nano-silicon dispersion with a concentration of 0.16 g / L.
[0046] S2: 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide were added to the nano-silicon dispersion and stirred at 4°C to obtain a mixture. Ethylenediamine was then added to the mixture and reacted at 4°C for 16 hours. The product was thoroughly washed with acetone and deionized water in sequence and dried to obtain modified nano-silicon.
[0047] The amount of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride added is 22% of the mass of the nano-silicon; the amount of N-hydroxysuccinimide added is 22% of the mass of the nano-silicon. The amount of ethylenediamine added is 5% of the volume of the mixed liquid.
[0048] Nano-silicon comprises nano-silicon I, nano-silicon II, and nano-silicon III in a mass ratio of 1:1.3:0.6; nano-silicon I has an average particle size of 100 nm and a specific surface area of 60 m². 2 / g, model MG-Si-100; average particle size of nano-silicon II 200nm, specific surface area 45m². 2 / g, model MG-Si-200; average particle size of nano-silicon III 1000nm, specific surface area 16m² 2 / g, model MG-Si-1000. Purchased from Shanghai Maoguo Nanotechnology Co., Ltd.
[0049] (2) Under a nitrogen atmosphere, the modified nano-silicon prepared in step (1) was ultrasonically dispersed with sulfoxide, wherein the molar ratio of sulfoxide to modified nano-silicon was 1.7:1. N,N-dimethylformamide was added, wherein the molar ratio of N,N-dimethylformamide to sulfoxide was 0.2:1; the temperature was raised to 75°C, and the modified conductive material was added. The mixture was reacted at 75°C for 22 h to obtain a mixed solution; the mass ratio of modified nano-silicon to the modified conductive material was 5:1.
[0050] (3) The mixture obtained in step (2) is spray-dried at an inlet temperature of 230°C and an outlet temperature of 130°C to obtain a lithium battery anode material based on modified biomass carbon material.
[0051] The preparation method of the modified conductive material includes the following steps:
[0052] (1) A mixture of carbon nanotubes, graphene and biomass carbon materials in a mass ratio of 0.4:1:1.5 was obtained;
[0053] (2) Mix 1 part by mass of fuming sulfuric acid and 98 parts by mass of water, stir evenly, add 32 parts by mass of the mixture, stir at 82°C for 4 hours, cool to room temperature, filter, and dry to obtain the modified conductive material.
[0054] The preparation method of the biomass carbon material includes the following steps: take 5 parts by mass of straw and crush it to less than 40 mesh, mix it evenly with 11 parts by mass of 1-allyl-3-methylimidazolium chloride, stir at 600 rpm for 16 h, place it in a tube furnace for sintering, heat it to 820°C at a heating rate of 4°C / min, keep it at a constant temperature for 2.5 h, then cool it down to room temperature at a cooling rate of 4°C / min, grind it into powder, pass it through a 100-mesh sieve, and obtain the biomass carbon material.
[0055] The carbon nanotubes have an inner diameter of 10-20 nm, a length of 5-15 μm, and a specific surface area of 120-180 m². 2 / g of multi-walled carbon nanotubes. Purchased from Shanghai Maoguo Nanotechnology Co., Ltd.
[0056] The graphene has a thickness of 1-5 nm; a single-layer sheet diameter of 5-45 μm; an electrical conductivity of 100,000 S / m; and a specific surface area of 24 m². 2 / g. Purchased from Shanghai Maoguo Nanotechnology Co., Ltd.
[0057] Example 2
[0058] This embodiment provides a method for preparing a lithium battery anode material based on modified biomass carbon material, including the following steps:
[0059] (1) Preparation of modified nano-silicon:
[0060] S1: Mix nano-silicon and deionized water, and ultrasonically disperse at 5°C for 35 min to obtain a nano-silicon dispersion with a concentration of 0.17 g / L.
[0061] S2: 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide were added to the nano-silicon dispersion and stirred at 2°C to obtain a mixture. Ethylenediamine was then added to the mixture and reacted at 2°C for 17 h. The product was thoroughly washed with acetone / deionized water and dried to obtain modified nano-silicon.
[0062] The amount of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride added is 20% to 23% of the mass of nano-silicon; the amount of N-hydroxysuccinimide added is 23% of the mass of nano-silicon; and the amount of ethylenediamine added is 6% of the volume of the mixed liquid.
[0063] Nano-silicon comprises nano-silicon I, nano-silicon II, and nano-silicon III in a mass ratio of 1:1.2:0.7; nano-silicon I has an average particle size of 100 nm and a specific surface area of 60 m². 2 / g, model MG-Si-100; average particle size of nano-silicon II 200nm, specific surface area 45m². 2 / g, model MG-Si-200; average particle size of nano-silicon III 1000nm, specific surface area 16m² 2 / g, model MG-Si-1000. Purchased from Shanghai Maoguo Nanotechnology Co., Ltd.
[0064] (2) Under a nitrogen atmosphere, the modified nano-silicon prepared in step (1) was ultrasonically dispersed with sulfoxide, wherein the molar ratio of sulfoxide to modified nano-silicon was 1.5:1. N,N-dimethylformamide was added, wherein the molar ratio of N,N-dimethylformamide to sulfoxide was 0.3:1. The temperature was raised to 70°C, and the modified conductive material was added. The mixture was reacted at 70°C for 25 h to obtain a mixed solution; the mass ratio of modified nano-silicon to the modified conductive material was 7:1.
[0065] (3) The mixture obtained in step (2) is spray-dried at an inlet temperature of 220°C and an outlet temperature of 150°C to obtain a lithium battery anode material based on modified biomass carbon material.
[0066] The preparation method of the modified conductive material includes the following steps:
[0067] (1) Carbon nanotubes, graphene and biomass carbon materials in a mass ratio of 0.3:1:1.4 were mixed to obtain a mixture;
[0068] (2) Mix 1 part by mass of fuming sulfuric acid and 100 parts by mass of water, stir evenly, add 30 parts by mass of the mixture, stir at 80°C for 5 hours, cool to room temperature, filter, and dry to obtain the modified conductive material.
[0069] The preparation method of the biomass carbon material includes the following steps: take 5 parts by mass of straw and crush it to less than 40 mesh, mix it evenly with 12 parts by mass of 1-allyl-3-methylimidazolium chloride, stir at 500 rpm for 17 h, place it in a tube furnace for sintering, heat it to 830°C at a heating rate of 3°C / min, keep it at a constant temperature for 2 h, then cool it down to room temperature at a cooling rate of 5°C / min, grind it into powder, pass it through a 100-mesh sieve, and obtain the biomass carbon material.
[0070] The carbon nanotubes have an inner diameter of 10-20 nm, a length of 5-15 μm, and a specific surface area of 120-180 m². 2 / g of multi-walled carbon nanotubes. Purchased from Shanghai Maoguo Nanotechnology Co., Ltd.
[0071] The graphene has a thickness of 1-5 nm; a single-layer sheet diameter of 5-45 μm; an electrical conductivity of 100,000 S / m; and a specific surface area of 24 m². 2 / g. Purchased from Shanghai Maoguo Nanotechnology Co., Ltd.
[0072] Comparative Example 1
[0073] The difference between this comparative example and Example 1 is that carbon nanotubes, graphene, and biomass carbon materials in a mass ratio of 1:1:1 are mixed to obtain a mixture.
[0074] Comparative Example 2
[0075] The difference between this comparative example and Example 1 is that the modified conductive material is replaced with graphene, which has a thickness of 1-5 nm, a single-layer diameter of 5-45 μm, an electrical conductivity of 100,000 S / m, and a specific surface area of 24 m². 2 / g. Purchased from Shanghai Maoguo Nanotechnology Co., Ltd.
[0076] Comparative Example 3
[0077] The difference between this comparative example and Example 1 is that the nano-silicon includes nano-silicon I, nano-silicon II, and nano-silicon III in a mass ratio of 1:1:1; the average particle size of nano-silicon I is 100 nm, and the specific surface area is 60 m². 2 / g, model MG-Si-100; average particle size of nano-silicon II 200nm, specific surface area 45m². 2 / g, model MG-Si-200; average particle size of nano-silicon III 1000nm, specific surface area 16m² 2 / g, model MG-Si-1000. Purchased from Shanghai Maoguo Nanotechnology Co., Ltd.
[0078] Comparative Example 4
[0079] The difference between this comparative example and Example 1 is that the carbon nanotubes have an inner diameter of 15-30 nm, a length of 10-30 μm, an electrical conductivity of 1000 S / m, and a specific surface area of 50-80 m². 2 / g of multi-walled carbon nanotubes. Purchased from Xianfeng Nano.
[0080] Comparative Example 5
[0081] The difference between this comparative example and Example 1 is that the graphene has 4-6 carbon atom layers; the diameter of a single layer is 200 nm, and the specific surface area is 200 m². 2 / g. Purchased from Shanghai Maoguo Nanotechnology Co., Ltd. Model: MG-GR-01.
[0082] Performance testing
[0083] The negative electrode materials prepared in Examples 1-2 and Comparative Examples 1-5 and conductive carbon black were ground and mixed evenly in a mortar. A PVDF N-methylpyrrolidone (NMP) solution was added and stirred until homogeneous to obtain a slurry. The mass ratio of negative electrode material: conductive carbon black: PVDF was 90:5:5. This slurry was coated onto copper foil, dried, and rolled to form a negative electrode sheet. A lithium metal sheet was used as the counter electrode, Celgard 2400 as the separator, and 1 mol / L LiPF6 / EC (ethylene carbonate) + DMC (dimethyl carbonate) + EMC (ethyl methyl carbonate) (volume ratio 1:1:1) was used as the electrolyte. A simulated battery was assembled in an argon-filled glove box. After standing for 12 hours, the initial charge specific capacity and initial coulombic efficiency were measured.
[0084] Cyclic performance was tested at different temperatures (-30℃, 25℃, 50℃) and charge / discharge rates of 1.0C / 1.0C within a charge / discharge voltage range of 2.5-4.2V.
[0085] Table 1 Performance Test Results
[0086]
[0087]
[0088] As can be seen from the above performance test results, the batteries prepared by the negative electrode materials of Examples 1-2 have excellent overall performance, especially the cycle performance at high and low temperatures is improved. The overall performance of Example 1 is the most outstanding, which is mainly due to the synergistic effect between the raw materials.
[0089] The comparative examples, lacking the necessary technical solutions, showed significantly inferior performance compared to the exemplary examples in relevant tests. In Comparative Example 1, the different ratios of carbon nanotubes, graphene, and biomass carbon materials resulted in decreased cycle performance at high temperatures. In Comparative Example 2, replacing the modified conductive material with graphene led to varying degrees of performance degradation across the battery. In Comparative Example 3, the different proportions of nano-silicon resulted in a decrease in the initial coulombic efficiency of the lithium battery. Furthermore, the different parameters of carbon nanotubes in Comparative Example 4 and graphene in Comparative Example 5 resulted in decreased cycle performance at low temperatures. These experimental results further demonstrate the importance of the technical solutions defined in this invention for its technical effectiveness.
[0090] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a lithium battery anode material based on modified biomass carbon materials, characterized in that, Includes the following steps: (1) Preparation of modified nano-silicon: S1: Mix nano-silicon and deionized water, and disperse by ultrasonication to obtain a nano-silicon dispersion with a concentration of 0.15-0.17 g / L; S2: 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide were added to the nano-silicon dispersion and stirred evenly at 0-4℃ to obtain a mixture. Ethylenediamine was then added to the mixture and reacted at 0-4℃ for 15-17 h. After washing and drying, modified nano-silicon was obtained. (2) Under a nitrogen atmosphere, the modified nano-silicon prepared in step (1) is ultrasonically dispersed with thionyl chloride, and N,N-dimethylformamide is added. The temperature is raised to 70-80℃, and the modified conductive material is added. The mixture is reacted at 70-80℃ for 20-25h to obtain a mixture. (3) Spray dry the mixture from step (2) to obtain a lithium battery anode material based on modified biomass carbon material; Methods for preparing modified conductive materials include: A. Mix carbon nanotubes, graphene, and biomass carbon materials in a mass ratio of (0.3-0.5):1:(1.4-1.6) to obtain a mixture; B. Mix 1 part by weight of fuming sulfuric acid and 95-100 parts by weight of water, stir evenly, then add 30-35 parts by weight of the mixture, stir at 80-85℃ for 3-5 hours, cool to room temperature, filter, and dry to obtain the modified conductive material. The preparation method of biomass carbon material includes: taking 5 parts by weight of straw, crushing it, and mixing it evenly with 10-12 parts by weight of 1-allyl-3-methylimidazolium chloride, stirring for 15-17 hours, placing it in a tube furnace for sintering, heating to 800-830℃, maintaining the temperature for 2-3 hours, cooling to room temperature, grinding, and sieving to obtain biomass carbon material.
2. The method for preparing lithium battery anode material based on modified biomass carbon material according to claim 1, characterized in that, Nano-silicon comprises nano-silicon I, nano-silicon II, and nano-silicon III in a mass ratio of 1:(1.2-1.4):(0.5-0.7); nano-silicon I has an average particle size of 100 nm and a specific surface area of 60 m². 2 / g; the average particle size of nano-silicon II is 200nm, and the specific surface area is 45m². 2 / g; Nano-silicon III has an average particle size of 1000nm and a specific surface area of 16m². 2 / g.
3. The method for preparing lithium battery anode material based on modified biomass carbon material according to claim 1, characterized in that, The carbon nanotubes are multi-walled carbon nanotubes with an inner diameter of 10-20 nm, a length of 5-15 μm, and a specific surface area of 120-180 m². 2 / g.
4. The method for preparing lithium battery anode material based on modified biomass carbon material according to claim 1, characterized in that, The graphene has a thickness of 1-5 nm; a single-layer diameter of 5-45 μm; an electrical conductivity of 100,000 S / m; and a specific surface area of 24 m². 2 / g.
5. The method for preparing lithium battery anode material based on modified biomass carbon material according to claim 1, characterized in that, The mass ratio of modified nano-silicon to the modified conductive material is (4-7):
1.
6. The method for preparing lithium battery anode material based on modified biomass carbon material according to claim 1, characterized in that, The molar ratio of sulfoxide to modified nano-silicon is (1.5-2.0):1; the molar ratio of N,N-dimethylformamide to sulfoxide is (0.1-0.3):
1.
7. The method for preparing lithium battery anode material based on modified biomass carbon material according to claim 1, characterized in that, The amount of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride added is 20% to 23% of the mass of nano-silicon; the amount of N-hydroxysuccinimide added is 20% to 23% of the mass of nano-silicon; and the amount of ethylenediamine added is 3% to 6% of the volume of the mixed liquid.
8. A lithium battery anode material based on modified biomass carbon material prepared by the preparation method according to any one of claims 1-7.