Multi-dimensional multi-scale carbon composite coated silicon-based lithium ion battery negative electrode material and preparation method thereof

Abstract

The application provides a multi-dimensional multi-scale carbon composite coated Si-based lithium ion battery negative electrode material and a preparation method thereof. The preparation method uses nanometer silicon as raw material, graphite as auxiliary material, resin as grinding medium and carbon material for coating, and nickel nitrate as catalyst. The resin and the graphite are mixed, then are peeled by a three-roll differential grinding machine, and the mixture is cleaned by alcohol for different times. After the addition of the nickel nitrate, Si is added, and then the mixture is mixed by the three-roll differential grinding machine. After cold freeze drying and heat treatment, the Si-based negative electrode material coated by the graphene-like carbon nanotube amorphous carbon composite is obtained. Compared with the prior art, the application has good conductivity and stability, can improve the energy density, cycle performance, rate performance and other electrical properties of the battery, and can meet the demand of the battery energy storage field for new materials.

Description

Technical Field

[0001] This invention relates to a multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material and its preparation method, belonging to the field of lithium-ion battery anode materials. Background Technology

[0002] With the development of new energy vehicles, consumers have higher demands for vehicle range. Industry experts indicate that current carbon anode materials have a specific capacity of 360 mAh / g, very close to the theoretical specific capacity (372 mAh / g), leaving little room for improvement. Therefore, many institutions and researchers are developing new alternative materials. Silicon-based anode materials are considered promising new materials by the industry and are a key research focus for mainstream manufacturers. They are among the most likely new anode materials for large-scale application in the future. Silicon (Si), as an abundant natural resource, has a low plateau voltage and extremely high theoretical capacity (4200 mAh / g), offering advantages in energy density and efficiency, with significant untapped potential. Silicon-based anode materials have a specific capacity of 3500 mAh / g, demonstrating enormous potential and a positive effect on improving battery energy density.

[0003] During lithium-ion insertion and extraction, silicon particles undergo a significant volume expansion (-300%). This expansion generates intense mechanical stress on the silicon particle surface, leading to electrode expansion and silicon particle fragmentation. Electrode expansion can cause cracking of the electrode material, increasing electrical contact loss between the silicon particles and the electrode, resulting in reduced electrode conductivity. Simultaneously, electrode expansion can force the electrolyte into the micropores of the separator, hindering lithium-ion diffusion. Electrode expansion can also cause the battery to bulge, potentially leading to safety issues.

[0004] In view of this, it is indeed necessary to propose a multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material and its preparation method to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material and its preparation method.

[0006] To achieve the above objectives, this invention provides a method for preparing a multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material, mainly comprising the following steps:

[0007] Step 1: Add 1-10% graphite to 90-99wt% resin and mix it in a water bath at 40-70℃ for 10-30 minutes by stirring to obtain mixture A;

[0008] Step 2: The mixture A from Step 1 is peeled off using a three-roll mill. After repeated peeling, the mixture B containing graphene-like nanosheets is collected from the discharge roller.

[0009] Step 3: Remove some resin by dissolving it with alcohol. Add 50-200 vol% alcohol to the mixture B obtained by peeling. Stir and sonicate for 10 minutes. Centrifuge in a centrifuge tube and remove impurities. Repeat step 3 and continue to wash with alcohol. Finally, centrifuge to obtain substance C.

[0010] Step 4: Using the impurity liquid removed by centrifugation after the last alcohol cleaning of the resin in Step 3 as a solvent, measure an amount of the impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.01-0.5wt% nickel nitrate raw material in it, and then mix it with substance C and stir for 1-10 minutes to obtain mixture D.

[0011] Step 5: Add mixture D to nano-silicon and stir for 5-10 minutes to obtain mixture E. The amount of mixture D added accounts for 5-18 wt% of the mass fraction of mixture E.

[0012] Step 6: The mixture E is then subjected to further thorough peeling and mixing through a three-roll differential mill. After repeated peeling and reprocessing, the mixture F is collected from the discharge roller.

[0013] Step 7: Place mixture F in a freeze dryer and freeze dry it under vacuum at -50°C to -30°C to obtain mixture G;

[0014] Step 8: Place the freeze-dried mixture G in a tube furnace and heat-treat it under argon atmosphere, from room temperature at a rate of 2-10°C / min. -1 The heating rate is increased to 600-1000℃, held for 1-5 hours, and then allowed to cool naturally to room temperature to obtain a multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material.

[0015] As a further improvement of the present invention, the nano-silicon is used as a raw material, the graphite is used as an auxiliary material, the resin is used as a grinding medium and a coated carbon raw material, the nickel nitrate is used as a catalyst and a dopant, the resin is one of polyvinyl alcohol, polyvinylidene fluoride resin, epoxy resin, phenolic resin or polyethylene resin liquid, and the graphite is at least one of flake graphite and expanded graphite.

[0016] As a further improvement of the present invention, in step 2, the number of cyclic peelings is 15-17 times, and in step 3, the alcohol cleaning is repeated 2-6 times.

[0017] As a further improvement of the present invention, the three-roll differential grinding mill includes a discharge roller N1, a center roller N2 and a feed roller N3, wherein the rotational speed ratio of the feed roller N3, the center roller N2 and the discharge roller N1 is 1:3:9, and during the cyclic peeling process, the gap between the center roller N2 and the feed roller N3 is always greater than the gap between the discharge roller N1 and the center roller N2.

[0018] As a further improvement of the present invention, during the first to fourth cyclic peeling, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 40 and 200 μm.

[0019] As a further improvement of the present invention, during the 5th to 8th cyclic peeling, the gap between the center roller N2 and the feed roller N3 and the gap between the discharge roller N1 and the center roller N2 are both between 10-40 μm.

[0020] As a further improvement of the present invention, during the 9th to 12th cyclic peeling, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 2.5 and 10 μm.

[0021] As a further improvement of the present invention, after the 13th cyclic peeling, the gap between the center roller N2 and the feed roller N3 and the gap between the discharge roller N1 and the center roller N2 are both between 0.5-2.5 μm.

[0022] As a further improvement of the present invention, in step 6, the number of cyclic peeling is 2-3 times. After the cyclic peeling is completed, the gap between the center roller N2 and the feed roller N3 and the gap between the discharge roller N1 and the center roller N2 are both between 0.5-2.5μm.

[0023] To achieve the above objectives, the present invention also provides a multidimensional and multi-scale carbon composite coated silicon-based lithium-ion battery anode material, which is prepared by the preparation method of the multidimensional and multi-scale carbon composite coated silicon-based lithium-ion battery anode material as described above.

[0024] The beneficial effects of this invention are as follows: This invention employs a composite coating of graphene-like nanosheets, carbon nanotubes, and amorphous carbon to encapsulate silicon-based anode materials, reducing the polarization and impedance of Si during charge and discharge processes. Furthermore, the three dimensions and scales of carbon composite coating exhibit excellent modification effects. Individual coatings, along with the combined coating of graphene-like nanosheets, carbon nanotubes, and amorphous carbon on the Si surface, form a three-dimensional network structure that facilitates Li+ transport. Additionally, the graphene-like nanosheets, carbon nanotubes, and amorphous carbon constitute a "protective barrier," suppressing side reactions of the electrolyte on Si, effectively improving the electrochemical performance and stability of the material. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to specific embodiments.

[0026] It should be noted that, in order to avoid obscuring the present invention with unnecessary details, the structures and / or processing steps closely related to the present invention are omitted, while other details that are not closely related to the present invention are omitted.

[0027] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0028] This invention discloses a multidimensional, multi-scale carbon composite-coated silicon-based lithium-ion battery anode material, mainly using nano-silicon as raw material, graphite as auxiliary material, resin as grinding medium and coating carbon raw material, and nickel nitrate as catalyst and dopant. The silicon raw material has a length and width both less than 100 nm. The resin is one of polyvinyl alcohol, polyvinylidene fluoride resin, epoxy resin, phenolic resin, or liquid polyethylene resin. The graphite is at least one of flake graphite and expanded graphite, with a carbon content ≥96%. The flake graphite raw material has a length and width of 50-500 μm and a thickness of 5-50 μm, while the expanded graphite raw material has a length and width of 300-2000 μm and a thickness of 50-500 μm. The preparation method of the multidimensional, multi-scale carbon composite-coated silicon-based lithium-ion battery anode material mainly includes the following steps:

[0029] Step 1: Add 1-10% graphite to 90-99wt% resin and mix it in a water bath at 40-70℃ for 10-30 minutes by stirring to obtain mixture A;

[0030] Step 2: The mixture A from Step 1 is peeled off using a three-roll mill. After repeated peeling, the mixture B containing graphene-like nanosheets is collected from the discharge roller.

[0031] Step 3: Remove some resin by dissolving it with alcohol. Add 50-200 vol% alcohol to the mixture B obtained by peeling. Stir and sonicate for 10 minutes. Centrifuge in a centrifuge tube and remove impurities. Repeat step 3 and continue to wash with alcohol. Finally, centrifuge to obtain substance C.

[0032] Step 4: Using the impurity liquid removed by centrifugation after the last alcohol cleaning of the resin in Step 3 as a solvent, measure an amount of the impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.01-0.5wt% nickel nitrate raw material in it, and then mix it with substance C and stir for 1-10 minutes to obtain mixture D.

[0033] Step 5: Add mixture D to nano-silicon and stir for 5-10 minutes to obtain mixture E. The amount of mixture D added accounts for 5-18 wt% of the mass fraction of mixture E.

[0034] Step 6: The mixture E is then subjected to further thorough peeling and mixing through a three-roll differential mill. After repeated peeling and reprocessing, the mixture F is collected from the discharge roller.

[0035] Step 7: Place mixture F in a freeze dryer and freeze dry it under vacuum at -50°C to -30°C to obtain mixture G;

[0036] Step 8: Place the freeze-dried mixture G in a tube furnace and heat-treat it under argon atmosphere, from room temperature at a rate of 2-10°C / min. -1 The heating rate is increased to 600-1000℃, held for 1-5 hours, and then allowed to cool naturally to room temperature to obtain a multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material.

[0037] Steps 1 through 8 will be described in detail below.

[0038] In step 2, the number of cyclic peeling cycles is 15-17. The three-roll differential speed grinding mill includes a discharge roller N1, a center roller N2, and a feed roller N3. The speed ratio of the feed roller N3, the center roller N2, and the discharge roller N1 is 1:3:9. During the cyclic peeling process, the gap between the center roller N2 and the feed roller N3 is always greater than the gap between the discharge roller N1 and the center roller N2.

[0039] It should be noted that the roller spacing varies with the number of peeling cycles. For example, during the first to fourth peeling cycles, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 40 and 200 μm. During the fifth to eighth peeling cycles, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 10 and 40 μm. During the ninth to twelfth peeling cycles, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 2.5 and 10 μm. After the thirteenth peeling cycle, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 0.5 and 2.5 μm.

[0040] In step 3, repeat this step to control the number of alcohol cleaning cycles to 2-6.

[0041] In step 6, the number of cyclic peeling is 2-3 times. After the cyclic peeling is completed, the gap between the center roller N2 and the feed roller N3 and the gap between the discharge roller N1 and the center roller N2 are both between 0.5-2.5μm.

[0042] The following description, in conjunction with examples and comparative examples, provides a detailed explanation.

[0043] Example 1 specifically includes the following steps:

[0044] Step 1: Add 4% flake graphite to 96wt% resin and mix it in a 50℃ water bath by stirring for 15 minutes to obtain mixture A;

[0045] Step 2: The mixture A from Step 2 is then exfoliated using a three-roll mill. After 16 cycles of exfoliation, graphene-like nanosheets B are obtained. During the first 4 cycles of exfoliation, the gap between N3 and N2 is 100 μm, and the gap between N2 and N1 is 50 μm. During the 5th to 8th cycles of exfoliation, the gap between N3 and N2 is 25 μm, and the gap between N2 and N1 is 12 μm. During the 9th to 12th cycles of exfoliation, the gap between N3 and N2 is 6 μm, and the gap between N2 and N1 is 3 μm. During the 13th to 16th cycles of exfoliation, the gap between N3 and N2 is 1.5 μm, and the gap between N2 and N1 is 0.5 μm.

[0046] Step 3: Remove some resin by dissolving it with alcohol. Add 100 vol% alcohol to the mixture B obtained by peeling. Stir and sonicate for 10 minutes. Centrifuge in a centrifuge tube to remove impurities. Repeat this step to wash with alcohol 3 times. Finally, centrifuge to obtain substance C.

[0047] Step 4: Using the impurity liquid removed by centrifugation after the last alcohol cleaning of the resin in Step 3 as a solvent, measure an amount of the impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.05wt% nickel nitrate raw material in it, and then mix and stir with substance C for 5 minutes to obtain mixture D.

[0048] Step 5: Add mixture D to nano-silicon and stir for 8 minutes to obtain mixture E. The amount of mixture D added accounts for 12 wt% of the mass fraction of mixture E.

[0049] Step 6: The mixture E is then further separated and mixed using a three-roll differential mill. After three more separation cycles, the gap between N3 and N2 is set to 1.5 μm, and the gap between N2 and N1 is set to 0.5 μm. The mixture F is then collected from the discharge roller.

[0050] Step 7: Place mixture F in a freeze dryer and freeze dry it under vacuum at -45°C to obtain mixture G;

[0051] Step 8: Place the freeze-dried mixture G in a tube furnace and heat-treat it under argon atmosphere, from room temperature at a rate of 5°C / min. -1 The temperature was increased to 850℃, held for 3 hours, and then allowed to cool naturally to room temperature to obtain a multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material.

[0052] Weigh out 0.07g of the multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material prepared in this embodiment, 0.015g of acetylene black (conductive agent), and 0.015g of PVDF (HSV900, binder). After thorough grinding, add 0.4mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120°C for 10h, cut it into 12mm diameter discs and assemble them in an argon-atmospheric glove box. Use a lithium metal sheet as the counter electrode, 1M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25°C, at 1A g... -1 Under conditions where the voltage window is 0-1.5V, constant current charge-discharge tests were conducted on batteries assembled from multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode materials. The test results were obtained at 1A g. -1 The discharge specific capacity after 500 cycles under the specified conditions is 948.4 mAh g. -1 In 1A g -1 Under these conditions, the capacity retention rate after 500 cycles is 84%, the initial internal resistance is 2.15Ω, and the capacity is 1A g. -1 The internal resistance after 500 cycles is 3.2Ω.

[0053] Example 2 specifically includes the following steps:

[0054] Step 1: Add 2% expanded graphite to 98wt% resin and mix it in a 50℃ water bath by stirring for 15 minutes to obtain mixture A;

[0055] Step 2: The mixture A from Step 2 is then exfoliated using a three-roll mill. After 15 cycles of exfoliation, graphene-like nanosheets B are obtained. During the first 4 cycles of exfoliation, the gap between N3 and N2 is 100 μm, and the gap between N2 and N1 is 50 μm. During the 5th to 8th cycles of exfoliation, the gap between N3 and N2 is 25 μm, and the gap between N2 and N1 is 12 μm. During the 9th to 12th cycles of exfoliation, the gap between N3 and N2 is 6 μm, and the gap between N2 and N1 is 3 μm. During the 13th to 15th cycles of exfoliation, the gap between N3 and N2 is 1.5 μm, and the gap between N2 and N1 is 0.5 μm.

[0056] Step 3: Remove some resin by dissolving it with alcohol. Add 100 vol% alcohol to the mixture B obtained by peeling. Stir and sonicate for 10 minutes. Centrifuge in a centrifuge tube to remove impurities. Repeat this step to control the number of alcohol washings to 2. Finally, centrifuge to obtain substance C.

[0057] Step 4: Using the impurity liquid removed by centrifugation after the last alcohol cleaning of the resin in Step 3 as a solvent, measure an amount of the impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.02wt% nickel nitrate raw material in it, and then mix and stir with substance C for 5 minutes to obtain mixture D.

[0058] Step 5: Add mixture D to nano-silicon and stir for 8 minutes to obtain mixture E. The amount of mixture D added accounts for 6 wt% of the mass fraction of mixture E.

[0059] Step 6: The mixture E is then further separated and mixed using a three-roll differential mill. After three more separation cycles, the gap between N3 and N2 is set to 1.5 μm, and the gap between N2 and N1 is set to 0.5 μm. The mixture F is then collected from the discharge roller.

[0060] Step 7: Place mixture F in a freeze dryer and freeze dry it under vacuum at -45°C to obtain mixture G;

[0061] Step 8: Place the freeze-dried mixture G in a tube furnace and heat-treat it under argon atmosphere, from room temperature at a rate of 5°C / min. -1 The temperature was increased to 1000℃, held for 3 hours, and then allowed to cool naturally to room temperature to obtain a multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material.

[0062] Weigh out 0.07g of the multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material prepared in this embodiment, 0.015g of acetylene black (conductive agent), and 0.015g of PVDF (HSV900, binder). After thorough grinding, add 0.4mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120°C for 10h, cut it into 12mm diameter discs and assemble them in an argon-atmospheric glove box. Use a lithium metal sheet as the counter electrode, 1M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25°C, at 1A g... -1 Under conditions where the voltage window is 0-1.5V, constant current charge-discharge tests were conducted on batteries assembled from multidimensional, multi-scale carbon-coated silicon-based lithium-ion battery anode materials. The test results were obtained at 1A g. -1 The discharge specific capacity after 500 cycles under the specified conditions is 904.3 mAh g. -1 In 1A g -1 Under the given conditions, the capacity retention after 500 cycles is 78%, the initial internal resistance is 3.5Ω, and the capacity is 1A g. -1 The internal resistance after 500 cycles is 6.3Ω.

[0063] Example 3 specifically includes the following steps:

[0064] Step 1: Add 10% flake graphite to 90wt% resin and mix them in a 50℃ water bath by stirring for 15 minutes to obtain mixture A;

[0065] Step 2: The mixture A from Step 2 is then exfoliated using a three-roll mill. After 15 cycles of exfoliation, graphene-like nanosheets B are obtained. During the first 4 cycles of exfoliation, the gap between N3 and N2 is 100 μm, and the gap between N2 and N1 is 50 μm. During the 5th to 8th cycles of exfoliation, the gap between N3 and N2 is 25 μm, and the gap between N2 and N1 is 12 μm. During the 9th to 12th cycles of exfoliation, the gap between N3 and N2 is 6 μm, and the gap between N2 and N1 is 3 μm. During the 13th to 16th cycles of exfoliation, the gap between N3 and N2 is 1.5 μm, and the gap between N2 and N1 is 0.5 μm.

[0066] Step 3: Remove some resin by dissolving it with alcohol. Add 100 vol% alcohol to the mixture B obtained by peeling. Stir and sonicate for 10 minutes. Centrifuge in a centrifuge tube to remove impurities. Repeat this step to control the number of alcohol washings to 6. Finally, centrifuge to obtain substance C.

[0067] Step 4: Using the impurity liquid removed by centrifugation after the last alcohol cleaning of the resin in Step 3 as a solvent, measure an amount of the impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.05wt% nickel nitrate raw material in it, and then mix and stir with substance C for 5 minutes to obtain mixture D.

[0068] Step 5: Add mixture D to nano-silicon and stir for 8 minutes to obtain mixture E. The amount of mixture D added accounts for 10 wt% of the mass fraction of mixture E.

[0069] Step 6: The mixture E is then further separated and mixed using a three-roll differential mill. After three more separation cycles, the gap between N3 and N2 is set to 1.5 μm, and the gap between N2 and N1 is set to 0.5 μm. The mixture F is then collected from the discharge roller.

[0070] Step 7: Place mixture F in a freeze dryer and freeze dry it under vacuum at -45°C to obtain mixture G;

[0071] Step 8: Place the freeze-dried mixture G in a tube furnace and heat-treat it under argon atmosphere, from room temperature at a rate of 8°C / min. -1 The temperature was increased to 700℃, held for 3 hours, and then allowed to cool naturally to room temperature to obtain a multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material.

[0072] Weigh out 0.07g of the multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material prepared in this embodiment, 0.015g of acetylene black (conductive agent), and 0.015g of PVDF (HSV900, binder). After thorough grinding, add 0.4mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120°C for 10h, cut it into 12mm diameter discs and assemble them in an argon-atmospheric glove box. Use a lithium metal sheet as the counter electrode, 1M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25°C, at 1A g... -1 Under conditions where the voltage window is 0-1.5V, constant current charge-discharge tests were conducted on batteries assembled from multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode materials. The test results were obtained at 1A g. -1 The discharge specific capacity after 500 cycles under the specified conditions is 843.6 mAh g. -1 In 1A g -1 Under these conditions, the capacity retention rate after 500 cycles is 81%, the initial internal resistance is 3.65Ω, and the capacity is 1A g. -1 The internal resistance after 500 cycles is 6.8Ω.

[0073] Comparative Example 1 differs from Example 1 in that it does not involve the use of a three-roll mill for peeling, phenolic resin, or nickel nitrate. As a result, there is no carbon nanotube or amorphous carbon coating, and instead, the battery is assembled directly using nano-silicon raw materials.

[0074] Weigh out 0.07g of nano-Si raw material, 0.015g of acetylene black (conductive agent), and 0.015g of PVDF (HSV900, binder) for this comparative example. After thorough grinding, add 0.4mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120℃ for 10h, cut it into 12mm diameter discs and assemble them in an argon-atmospheric glove box. Use a lithium metal sheet as the counter electrode, 1M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25℃, at 1A g... -1 Under conditions where the voltage window is 0-1.5V, constant current charge-discharge tests were conducted on batteries assembled from nano-Si raw materials at 1A g. -1 The discharge specific capacity after 500 cycles under the specified conditions is 85.5 mAh g. -1 In 1A g -1 Under these conditions, the capacity retention rate after 500 cycles is 7%, the initial internal resistance is 3.7Ω, and the capacity is 1A g. -1 The internal resistance after 500 cycles is 20.6Ω.

[0075] Comparative Example 2 differs from Example 1 in that it does not involve the removal of flake graphite using a three-roll mill, but includes phenolic resin and no nickel nitrate. After heat treatment, it exhibits amorphous carbon coating but lacks carbon nanotubes and graphene-like nanosheets, thus forming only amorphous carbon-coated silicon nanoparticles. The specific preparation steps are as follows:

[0076] Step 1: Add phenolic resin to nano-silicon and stir for 8 minutes to obtain mixture A. The amount of phenolic resin added accounts for 6 wt% of the mass fraction of mixture A.

[0077] Step 2: Mixture A is further thoroughly mixed using a three-roll differential mill, and then the mixture is circulated and mixed 3 times. The gap between N3 and N2 is set to 1.5 μm, and the gap between N2 and N1 is set to 0.5 μm. Mixture B is collected from the discharge roller.

[0078] Step 3: Place mixture B in a freeze dryer and freeze dry it under vacuum at -45°C to obtain mixture C;

[0079] Step 4: Place the freeze-dried mixture C in a tube furnace and heat-treat it under argon atmosphere, from room temperature at a rate of 5°C / min.-1 The temperature was increased to 850℃, held for 3 hours, and then allowed to cool naturally to room temperature to obtain amorphous carbon-coated nano-silicon battery anode material.

[0080] Weigh out 0.07 g of the amorphous carbon-coated nano-silicon anode material prepared in this comparative example, 0.015 g of acetylene black (conductive agent), and 0.015 g of PVDF (HSV900, binder). After thorough grinding, add 0.4 mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120 °C for 10 h, cut it into 12 mm diameter discs and assemble them in an argon-atmosphere glove box. Use a lithium metal sheet as the counter electrode, 1 M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25 °C, at 1 A g... -1 A constant current charge-discharge test was conducted on a battery assembled with amorphous carbon-coated nano-silicon anode material under conditions with a voltage window of 0-1.5V. The test was performed at 1Ag. -1 The discharge specific capacity after 500 cycles under the specified conditions is 200.6 mAh g. -1 In 1A g -1 Under these conditions, the capacity retention rate after 500 cycles is 15%, the initial internal resistance is 3.25Ω, and the capacity is 1A g. -1 The internal resistance after 500 cycles under the given conditions is 18.4Ω.

[0081] Comparative Example 3 differs from Example 1 in that it involves peeling off flake graphite using a three-roll mill, but all phenolic resin is washed away at the end, and there is no nickel nitrate. Therefore, no heat treatment is required, and there are no carbon nanotubes or amorphous carbon coatings. Only graphene-like nanosheets and nano-silicon composites are formed.

[0082] The preparation method of the graphene-like composite nano-silicon battery cathode material in this comparative example uses nano-silicon as raw material, flake graphite as auxiliary material, and phenolic resin as grinding medium. The specific steps are as follows:

[0083] Step 1: Add 4 wt% flake graphite to 96 wt% phenolic resin and mix them in a 50°C water bath by stirring for 15 min to obtain mixture A;

[0084] Step 2: The mixture A obtained in Step 1 is peeled using a three-roll differential mill. After 16 peeling cycles, mixture B is collected from the discharge roller. During the first 4 peeling cycles, the gap between N3 and N2 is 100 μm, and the gap between N2 and N1 is 50 μm. During the 5th to 8th peeling cycles, the gap between N3 and N2 is 25 μm, and the gap between N2 and N1 is 12 μm. During the 9th to 12th peeling cycles, the gap between N3 and N2 is 6 μm, and the gap between N2 and N1 is 3 μm. During the 13th to 16th peeling cycles, the gap between N3 and N2 is 1.5 μm, and the gap between N2 and N1 is 0.5 μm.

[0085] Step 3: Remove resin by dissolving it with alcohol. Add 100 vol% alcohol to the mixture B obtained by peeling, stir and sonicate for 10 minutes, then centrifuge in a centrifuge tube to remove impurities. Repeat this step to control the number of alcohol washings to 15 times. Finally, centrifuge to obtain substance C.

[0086] Step 4: Add substance C to nano-Si and stir for 8 minutes to obtain mixture D. The amount of substance C added accounts for 12 wt% of the mass fraction of mixture D.

[0087] Step 5: The mixture D is further thoroughly mixed by passing it through a three-roll differential mill, and then circulated and peeled 3 times. The gap between N3 and N2 is set to 1.5 μm, and the gap between N2 and N1 is set to 0.5 μm. The mixture E is collected from the discharge roller.

[0088] Step 6: Place mixture E in a freeze dryer and freeze dry it under vacuum at -45°C to obtain mixture F;

[0089] Step 7: Place the freeze-dried mixture F in a tube furnace and heat-treat it under argon atmosphere, from room temperature at a rate of 5°C / min. -1 The temperature was increased to 850℃, held for 3 hours, and then allowed to cool naturally to room temperature to obtain a graphene-like composite nano-silicon battery anode material.

[0090] Weigh out 0.07 g of the graphene-like composite nano-silicon anode material, 0.015 g of acetylene black (conductive agent), and 0.015 g of PVDF (HSV900, binder) prepared in this comparative example. After thorough grinding, add 0.4 mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120 °C for 10 h, cut it into 12 mm diameter discs and assemble them in an argon-atmospheric glove box. Use a lithium metal sheet as the counter electrode, 1 M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25 °C, at 1 A g... -1 A constant current charge-discharge test was conducted on a battery assembled from graphene-like composite nano-silicon anode material under conditions with a voltage window of 0-1.5V. The test was performed at 1Ag. -1 The discharge specific capacity after 500 cycles under the specified conditions is 150.5 mAh g. -1 In 1A g -1 Under these conditions, the capacity retention rate after 500 cycles is 12%, the initial internal resistance is 3.6Ω, and the capacity is 1A g. -1 The internal resistance after 500 cycles is 15.4Ω.

[0091] Comparative Example 4 differs from Example 1 in that it does not involve the removal of flake graphite by a three-roll mill, contains phenolic resin and nickel nitrate, and requires heat treatment. Therefore, it contains carbon nanotubes and amorphous carbon coating, thus forming carbon nanotube-amorphous carbon-coated nano-silicon.

[0092] This comparative method for preparing amorphous carbon-coated silicon-based battery anode material using carbon nanotubes employs nano-silicon as raw material, phenolic resin as the grinding medium and coating carbon material, and nickel nitrate as the catalyst and dopant. The specific preparation steps are as follows:

[0093] Step 1: Add phenolic resin to nano-silicon and stir for 8 minutes to obtain mixture A. The amount of phenolic resin added accounts for 6 wt% of the mass fraction of mixture A. Then, dissolve 0.05 wt% of nickel nitrate raw material in alcohol and add it to mixture A to obtain mixture B.

[0094] Step 2: Mixture B is further thoroughly mixed using a three-roll differential mill, and then the mixture is circulated and mixed 3 times. The gap between N3 and N2 is set to 1.5 μm, and the gap between N2 and N1 is set to 0.5 μm. Mixture C is collected from the discharge roller.

[0095] Step 3: Place mixture C in a freeze dryer and freeze dry it under vacuum at -45°C to obtain mixture D;

[0096] Step 4: Place the freeze-dried mixture D in a tube furnace and heat-treat it under argon atmosphere, from room temperature at a rate of 5°C / min. -1 The temperature was increased to 850℃, held for 3 hours, and then allowed to cool naturally to room temperature to obtain amorphous carbon-coated nano-Si nanotubes.

[0097] Weigh out 0.07 g of the amorphous carbon nanotube-coated silicon nanoparticle anode material prepared in this comparative example, 0.015 g of acetylene black (conductive agent), and 0.015 g of PVDF (HSV900, binder). After thorough grinding, add 0.4 mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120 °C for 10 h, cut it into 12 mm diameter discs and assemble them in an argon-atmospheric glove box. Use a lithium metal sheet as the counter electrode, 1 M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25 °C, in 1 Ag... -1 A constant current charge-discharge test was conducted on a battery assembled from amorphous carbon nanotube-coated silicon nanoparticle anode material under conditions with a voltage window of 0-1.5V. The test results were obtained at 1A g. -1 The discharge specific capacity after 500 cycles under the specified conditions is 430.9 mAh g. -1 In 1A g -1 Under these conditions, the capacity retention after 500 cycles is 28.7%, the initial internal resistance is 2.95Ω, and the capacity is 1A g. -1 The internal resistance after 500 cycles under the given conditions is 13.3Ω.

[0098] Comparative Example 5 differs from Example 1 in that the drying method used is oven drying instead of freeze drying, resulting in a multidimensional, multi-scale composite carbon-coated silicon-based lithium-ion battery anode material formed by oven drying.

[0099] The preparation method of this comparative example of a multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material uses nano-silicon as raw material, flake graphite as auxiliary material, phenolic resin as grinding medium and coating carbon raw material, and nickel nitrate as catalyst and dopant. The specific steps are as follows:

[0100] Step 1: Add 4 wt% flake graphite to 96 wt% phenolic resin and mix them in a 50°C water bath by stirring for 15 min to obtain mixture A;

[0101] Step 2: The mixture A obtained in Step 1 is peeled using a three-roll differential mill. After 16 peeling cycles, mixture B is collected from the discharge roller. During the first 4 peeling cycles, the gap between N3 and N2 is 100 μm, and the gap between N2 and N1 is 50 μm. During the 5th to 8th peeling cycles, the gap between N3 and N2 is 25 μm, and the gap between N2 and N1 is 12 μm. During the 9th to 12th peeling cycles, the gap between N3 and N2 is 6 μm, and the gap between N2 and N1 is 3 μm. During the 13th to 16th peeling cycles, the gap between N3 and N2 is 1.5 μm, and the gap between N2 and N1 is 0.5 μm.

[0102] Step 3: Remove some resin by dissolving it with alcohol. Add 100 vol% alcohol to the mixture B obtained by peeling. Stir and sonicate for 10 minutes. Centrifuge in a centrifuge tube to remove impurities. Repeat this step to wash with alcohol 3 times. Finally, centrifuge to obtain substance C.

[0103] Step 4: Using the impurity liquid removed by centrifugation after the last alcohol cleaning of the resin in Step 3 as a solvent, measure an amount of the impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.05wt% nickel nitrate raw material in it, and then mix and stir with substance C for 5 minutes to obtain mixture D.

[0104] Step 5: Add mixture D to nano Si and stir for 8 min to obtain mixture E. The amount of mixture D added accounts for 12 wt% of the mass fraction of mixture E.

[0105] Step 6: The mixture E is then subjected to further thorough peeling and mixing through a three-roll differential mill, and the peeling is repeated 3 times. The gap between N3 and N2 is set to 1.5 μm, and the gap between N2 and N1 is set to 0.5 μm. The mixture F is collected from the discharge roller.

[0106] Step 7: Place mixture F in an oven and dry it at 50°C to obtain mixture G;

[0107] Step 8: Place the dried mixture G in a tube furnace and heat-treat it under argon atmosphere, from room temperature at a rate of 5°C / min. -1 The temperature was increased to 850℃, held for 3 hours, and then allowed to cool naturally to room temperature to obtain a multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material.

[0108] Weigh out 0.07 g of the multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material, 0.015 g of acetylene black (conductive agent), and 0.015 g of PVDF (HSV900, binder) prepared in this comparative example. After thorough grinding, add 0.4 mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120 °C for 10 h, cut it into 12 mm diameter discs and assemble them in an argon-atmospheric glove box. Use lithium metal sheet as the counter electrode, 1 M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25 °C, at 1 A g -1 Under conditions where the voltage window is 0-1.5V, constant current charge-discharge tests were conducted on batteries assembled from multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode materials. The test results were obtained at 1A g. -1 The discharge specific capacity after 500 cycles under the specified conditions is 820 mAh g. -1 In 1Ag -1 Under the given conditions, the capacity retention after 500 cycles is 70.4%, the initial internal resistance is 3.5Ω, and the capacity is 1A g. -1 The internal resistance after 500 cycles is 7.9Ω.

[0109] Comparative Example 6 differs from Example 1 in the number of times the phenolic resin is cleaned. Example 1 was cleaned 4 times, while this comparative example was cleaned 1 time. The purpose of this is to differentiate the carbon coating thickness during subsequent heat treatment.

[0110] This comparative method for preparing amorphous carbon composite coated nano-silicon battery anode material using graphene-like nanosheets and carbon nanotubes employs nano-silicon as raw material, flake graphite as auxiliary material, phenolic resin as grinding medium and coating carbon raw material, and nickel nitrate as catalyst and dopant. The specific steps are as follows:

[0111] Step 1: Add 4 wt% flake graphite to 96 wt% phenolic resin and mix them in a 50°C water bath by stirring for 15 min to obtain mixture A;

[0112] Step 2: The mixture A obtained in Step 1 is peeled using a three-roll differential mill. After 16 peeling cycles, mixture B is collected from the discharge roller. During the first 4 peeling cycles, the gap between N3 and N2 is 100 μm, and the gap between N2 and N1 is 50 μm. During the 5th to 8th peeling cycles, the gap between N3 and N2 is 25 μm, and the gap between N2 and N1 is 12 μm. During the 9th to 12th peeling cycles, the gap between N3 and N2 is 6 μm, and the gap between N2 and N1 is 3 μm. During the 13th to 16th peeling cycles, the gap between N3 and N2 is 1.5 μm, and the gap between N2 and N1 is 0.5 μm.

[0113] Step 3: Remove some resin by dissolving it with alcohol. Add 100 vol% alcohol to the mixture B obtained by peeling. Stir and sonicate for 10 minutes. Centrifuge in a centrifuge tube to remove impurities. Repeat this step to ensure that the alcohol washing is done once. Finally, centrifuge to obtain substance C.

[0114] Step 4: Using the impurity liquid removed by centrifugation after the last alcohol cleaning of the resin in Step 3 as a solvent, measure an amount of the impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.05wt% nickel nitrate raw material in it, and then mix and stir with substance C for 5 minutes to obtain mixture D.

[0115] Step 5: Add mixture D to nano-silicon and stir for 8 minutes to obtain mixture E. The amount of mixture D added accounts for 12 wt% of the mass fraction of mixture E.

[0116] Step 6: The mixture E is then subjected to further thorough peeling and mixing through a three-roll differential mill, and the peeling is repeated 3 times. The gap between N3 and N2 is set to 1.5 μm, and the gap between N2 and N1 is set to 0.5 μm. The mixture F is collected from the discharge roller.

[0117] Step 7: Place mixture F in a freeze dryer and freeze dry it under vacuum at -45°C to obtain mixture G;

[0118] Step 8: Place the freeze-dried mixture G in a tube furnace and heat-treat it under argon atmosphere, from room temperature at a rate of 5°C / min. -1 The temperature was increased to 850℃, held for 3 hours, and then allowed to cool naturally to room temperature to obtain a graphene-like carbon nanotube amorphous carbon composite coated silicon-based lithium-ion battery anode material.

[0119] Weigh out 0.07 g of the graphene-like nanosheet carbon nanotube amorphous carbon-coated silicon-based lithium-ion battery anode material prepared in this comparative example, 0.015 g of acetylene black (conductive agent), and 0.015 g of PVDF (HSV900, binder). After thorough grinding, add 0.4 mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120 °C for 10 h, cut it into 12 mm diameter discs and assemble them in an argon-atmospheric glove box. Use a lithium metal sheet as the counter electrode, 1 M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25 °C, at 1 A g... -1 Under conditions with a voltage window of 0-1.5V, constant current charge-discharge tests were conducted on a battery assembled from amorphous carbon composite materials coated with graphene-like nanosheets and carbon nanotubes as the anode material of a silicon-based battery. The test results were obtained at 1A g.-1 The discharge specific capacity after 500 cycles under the specified conditions is 753.4 mAh g. -1 In 1A g -1 Under the given conditions, the capacity retention after 500 cycles is 76.4%, the initial internal resistance is 3.3Ω, and the capacity is 1A g. -1 The internal resistance after 500 cycles is 10.6Ω.

[0120] Table 1 below shows a performance comparison between the examples and the comparative examples.

[0121] Table 1 Performance comparison between the examples and comparative examples

[0122]

[0123]

[0124] In summary, the present invention employs a three-roll differential grinding and peeling technology. This technology overcomes the van der Waals forces between graphite layers by using the shear force generated by the differential speed of the three rollers and the interaction force formed between the high-viscosity resin and the surface of flake graphite / expanded graphite. This allows for the peeling of millimeter-thick flake graphite / expanded graphite to prepare a large number of nano-graphene sheets. The graphene is uniformly dispersed in situ in the resin, resulting in a better dispersion effect than traditional external methods.

[0125] This invention uses a nickel nitrate catalyst, which is dissolved in ethanol to prepare a nickel nitrate ethanol solution. The nickel nitrate ethanol solution is easy to mix evenly with the resin. During the subsequent heat treatment at 600-1000℃, it easily catalyzes the formation of carbon nanotubes in the resin. This method has better dispersibility than adding carbon nanotubes and saves costs.

[0126] Carbon nanotubes possess excellent electrical conductivity and a large specific surface area, making them suitable for direct application in lithium-ion batteries. Their unique tubular structure and intertwined network structure can accelerate the transport rate of Li+ ions, and carbon nanotubes themselves have a certain conductivity. The interlaced nanostructure provides shorter and faster transport channels for electrons and ions.

[0127] This invention prepares a mixture of graphene-like nanosheets, nickel nitrate, and a small amount of resin. Since the resin has a certain viscosity, the traditional drying technology can easily cause the mixture to form a paste-like agglomerate. By using freeze-drying technology, a powder with very good dispersion effect can be obtained.

[0128] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material, characterized in that, Includes the following steps: Step 1: Add 1-10% graphite to 90-99wt% resin and mix it in a water bath at 40-70℃ for 10-30 minutes by stirring to obtain mixture A; Step 2: The mixture A from Step 1 is peeled off using a three-roll mill. After peeling 15-17 times, the mixture B containing graphene-like nanosheets is collected from the discharge roller. Step 3: Remove some resin by dissolving it with alcohol. Add 50-200 vol% alcohol to the mixture B obtained by peeling. Stir and sonicate for 10 minutes. Centrifuge in a centrifuge tube and remove impurities. Repeat this step to wash with alcohol 2-6 times. Finally, centrifuge to obtain substance C. Step 4: Using the impurity liquid removed by centrifugation after the last alcohol cleaning of the resin in Step 3 as a solvent, measure an amount of the impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.01-0.5wt% nickel nitrate raw material in it, and then mix it with substance C and stir for 1-10 minutes to obtain mixture D. Step 5: Add mixture D to nano-silicon and stir for 5-10 minutes to obtain mixture E. The amount of mixture D added accounts for 5-18 wt% of the mass fraction of mixture E. Step 6: The mixture E is then subjected to further thorough peeling and mixing through a three-roll differential mill. After repeated peeling and reprocessing, the mixture F is collected from the discharge roller. Step 7: Place mixture F in a freeze dryer and freeze dry it under vacuum at -50°C to -30°C to obtain mixture G; Step 8: Place the freeze-dried mixture G in a tube furnace and heat-treat it under argon atmosphere, from room temperature at a rate of 2-10°C / min. -1 The temperature is increased to 600-1000℃, held for 1-5 hours, and then allowed to cool naturally to room temperature to obtain a multidimensional and multi-scale carbon composite coated silicon-based lithium-ion battery anode material. The multidimensional and multi-scale carbon composite coated silicon-based lithium-ion battery anode material is a graphene-like nanosheet, carbon nanotube, and amorphous carbon composite coated silicon-based lithium-ion battery anode material.

2. The preparation method of the multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material according to claim 1, characterized in that: The nano-silicon is used as the raw material, the graphite is used as the auxiliary material, the resin is used as the grinding medium and the coated carbon raw material, the nickel nitrate is used as the catalyst and dopant, the resin is one of polyvinyl alcohol, polyvinylidene fluoride resin, epoxy resin, phenolic resin or polyethylene resin liquid, and the graphite is at least one of flake graphite and expanded graphite.

3. The preparation method of the multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material according to claim 1, characterized in that: The three-roll differential grinding mill includes a discharge roller N1, a center roller N2, and a feed roller N3. The rotational speed ratio of the feed roller N3, the center roller N2, and the discharge roller N1 is 1:3:

9. During the cyclic peeling process, the gap between the center roller N2 and the feed roller N3 is always greater than the gap between the discharge roller N1 and the center roller N2.

4. The preparation method of the multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material according to claim 3, characterized in that: During the first to fourth cycles of peeling, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 40 and 200 μm.

5. The preparation method of the multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material according to claim 3, characterized in that: During the 5th to 8th cyclic peeling, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 10 and 40 μm.

6. The method for preparing the multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material according to claim 3, characterized in that: During the 9th to 12th cyclic peeling, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 2.5 and 10 μm.

7. The preparation method of the multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material according to claim 3, characterized in that: After the 13th cyclic peeling, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 0.5 and 2.5 μm.

8. The method for preparing the multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material according to claim 3, characterized in that: In step 6, the peeling cycle is repeated 2-3 times. After the peeling cycle is completed, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 0.5-2.5 μm.

9. A multidimensional, multi-scale carbon composite coated silicon-based lithium-ion battery anode material, characterized in that: It is prepared using the preparation method of the multidimensional and multi-scale carbon composite coated silicon-based lithium-ion battery anode material as described in any one of claims 1-8.

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