A silicon-carbon anode material based on a conductive carbon framework and its preparation method

Abstract

This invention relates to the field of silicon-carbon anode material technology, and particularly to a silicon-carbon anode material based on a conductive carbon framework and its preparation method. The method includes: obtaining raw coal gas through dry distillation; obtaining raw oil through ammonia washing of the raw coal gas; obtaining centrifugal liquid and centrifugal residue through supercentrifugation of the raw oil; obtaining a conductive carbon framework A by sequentially subjecting the centrifugal residue to pressure filtration, oxidation stabilization, surface modification, and carbonization; obtaining a heavy distillate by distillation to remove light components from the centrifugal liquid, adding a silicon-carbon composite modifier, and mixing to obtain a silicon-carbon coating agent B; and mixing the conductive carbon framework A, silicon-carbon coating agent B, and solvent C in a liquid phase to obtain a silicon-carbon anode material precursor, which is then sequentially subjected to ultrasonic vibration, high-speed shear emulsification, solvent evaporation coating, and heat treatment to obtain the silicon-carbon anode material. The silicon-carbon anode material obtained by this invention has the characteristics of low expansion rate and excellent cycle performance.

Description

Technical Field

[0001] This invention relates to the field of silicon-carbon anode material technology, and in particular to a silicon-carbon anode material based on a conductive carbon framework and its preparation method. Background Technology

[0002] Currently, the main anode materials for lithium-ion batteries are carbon materials, which possess low and stable operating potentials and good cycle performance. However, carbon materials have relatively low specific capacity, and the lithium storage capacity of the anode material is a key factor limiting the application range of lithium-ion batteries. In contrast, silicon has a large theoretical specific capacity (4200 mAh / g), an order of magnitude higher than that of graphite-based anode materials (372 mAh / g), and also has a low lithium intercalation potential. Furthermore, silicon is abundant in the Earth's crust and inexpensive, making it an ideal choice for next-generation lithium-ion battery anode materials.

[0003] Silicon-carbon composites are a type of silicon-based composite material. With their unique advantages and potential, they have attracted the attention of more and more researchers. Silicon and carbon have similar chemical properties, and carbon-based anode materials have small volume changes during charge and discharge, as well as good cycle stability and conductivity. Therefore, carbon-based materials are often used as the preferred matrix for composites with silicon.

[0004] In order to further improve the electrochemical performance of silicon-carbon composite materials as anode materials for lithium-ion batteries, such as cycle stability and reversible cycle capacity retention, and to obtain alternatives to graphite as a new generation of anode materials for lithium-ion batteries, researchers have conducted a lot of exploratory research in recent years and achieved certain results.

[0005] Chinese Patent CN103367727A discloses a silicon-carbon anode material for lithium-ion batteries and its preparation method. The method involves mixing nano-silicon, a dispersant, a binder, and particulate graphite in an organic solvent and drying the mixture to obtain a composite nano-silicon / graphite polymer. This composite nano-silicon / graphite polymer is then added to a dispersion of a carbon source precursor, mixed, and dried. Finally, the resulting material is heat-treated at 600–1150°C to obtain the silicon-carbon anode material for lithium-ion batteries. While this method is simple and controllable, the nano-silicon exhibits agglomeration during preparation. During cycling, the nano-silicon expands, and over long cycles, the particulate organic carbon still breaks down, causing the nano-silicon to directly contact the electrolyte, resulting in a decrease in cycle life.

[0006] Therefore, there is an urgent need to develop a method to prepare silicon-carbon anode materials with excellent and stable electrochemical performance. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, the technical problem solved by this invention is to provide a silicon-carbon anode material based on a conductive carbon skeleton and its preparation method. This invention combines a silicon-carbon coating agent with a conductive carbon skeleton, allowing silicon powder particles to penetrate into the conductive carbon skeleton. At the same time, a solvent evaporation coating method is used to form a complete, uniform, and dense coating layer, increasing the overall mechanical strength of the material and maintaining the integrity of the electrode structure. This results in a silicon-carbon anode material with low expansion rate and excellent cycle performance.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] A silicon-carbon anode material based on a conductive carbon framework and its preparation method, comprising the following steps:

[0010] 1) Raw coal is subjected to dry distillation to obtain raw coal gas; the raw coal gas is washed with ammonia water to obtain raw oil; the raw oil is subjected to super centrifugation to obtain centrifugal liquid and centrifugal residue;

[0011] 2) The centrifugal residue was subjected to pressure filtration, oxidation stabilization, surface modification and carbonization treatment in sequence to obtain conductive carbon skeleton A;

[0012] 3) The centrifuged liquid is distilled to remove the light components to obtain a heavy distillate, a silicon-carbon composite modifier is added, and the mixture is stirred to obtain silicon-carbon coating agent B;

[0013] 4) Conductive carbon skeleton A, silicon carbon coating agent B and solvent C are mixed in the liquid phase to obtain silicon carbon anode material precursor, and then subjected to ultrasonic vibration, high-speed shear emulsification, solvent evaporation coating and heat treatment to obtain silicon carbon anode material.

[0014] In step 1), the raw coal is any one or a mixture of two or more of bituminous coal, anthracite, and lignite; the dry distillation conditions are a furnace top space temperature of 880~1100℃; the raw oil specifications are: ash content <0.05%, moisture content <1.0%, and quinoline insoluble content ≥15%; quinoline insolubles include primary organic quinoline insolubles and secondary quinoline insolubles, wherein the content of primary organic quinoline insolubles is ≥10%, ash content is <0.05%, and particle size distribution is D. 50 : 0.5~1μm, D max : 1.5~2μm; secondary quinoline insoluble content ≥5%, ash content <0.05%, particle size distribution is D 50 5~30μm, D max : 40~50μm; the content of toluene-insoluble matter in the centrifuged residue is ≥80%, and the ash content is <0.05%.

[0015] In step 1), the conditions for supercentrifugation are: separation temperature 30~80℃, separation time 0.5~5h, centrifugation speed 5000~20000rad / min, and sieve mesh 100~800 mesh.

[0016] In step 2), the pressure filtration is performed once or multiple times. The extractant used in the first pressure filtration is any one or a mixture of two or more of the following: wash oil, pyridine, and quinoline. The reaction conditions are: extraction temperature 100~180℃, extraction time 1~8h, and sieve to obtain filter residue of 100~400 mesh. The mass ratio of extractant to centrifuged residue is (1~5):1.

[0017] Before performing secondary filtration, a primary filtration process is first performed. For the secondary filtration, the extractant is any one or a mixture of two or more of acetone, benzene, toluene, and xylene. The reaction conditions are: extraction temperature 40-80℃, extraction time 1-4h, sieve mesh size 200-800 mesh, and mass ratio of extractant to upper filter residue (0.2-2):1. For the third or higher filtration, the reaction conditions are the same as those for the primary or secondary filtration.

[0018] In step 2), the oxidation stabilization reaction conditions are: reaction temperature of 260~380℃, air flow rate of 1~10m3 / h, and treatment time of 1~8h.

[0019] Surface modification is a one-stage or multi-stage treatment. The reaction conditions are as follows: reaction temperature is 300~1200℃, modifier is water, CO2, KOH, K2CO3, NaOH, or Na2CO3, and reaction time is 0.5~10h.

[0020] The carbonization reaction conditions are as follows: under nitrogen protection, the nitrogen flow rate is 300~1200 ml / min, the heating rate is 1~10℃ / min, the temperature is 700~1800℃, and the final temperature holding time is 1~12 h.

[0021] In step 3), the distillation reaction conditions are: bottom temperature of 160~280℃, vacuum degree of 0.01~0.09MPa; mass ratio of silicon-carbon composite modifier to heavy distillate (0.2~1):1.

[0022] The silicon-carbon composite modifier is composed of the following components by weight percentage: epoxy resin, silane coupling agent, and nano-silicon powder, in a mass ratio of (6~10):(2~4):(1~5), and the silicon powder particle size distribution is D. 10 : 2~5, D 50 : 20~40, D max 120~150μm.

[0023] In step 4), solvent C is any one of carbon tetrachloride, toluene, pyridine, quinoline, heavy oil, and wash oil; the mass ratio of conductive carbon skeleton A, silicon carbon coating agent B, and solvent C is: A:B:C = 1:(0.5~4):(0.5~8); the reaction conditions for liquid phase mixing are: liquid phase temperature of 60~240℃, stirring speed of 200~1200 rad / min, and stirring time of 1~8h.

[0024] In step 4), the ultrasonic vibration reaction conditions are: ultrasonic vibration temperature of 30~80℃ and time of 0.5~6h; the high-speed shear emulsification reaction conditions are: emulsification temperature of 160~280℃, stirring speed of 800~2000rad / min and emulsification time of 0.5~4h.

[0025] In step 4), solvent evaporation coating is either a primary or secondary treatment. The primary treatment reaction conditions are: evaporation temperature of 260~380℃, vacuum degree of 0.01~0.09MPa, time of 2~6h, and rotation speed of 60~300rad / min. The secondary treatment reaction conditions are: reaction temperature of 400~800℃, vacuum degree of 0.01~0.09MPa, time of 2~6h, and rotation speed of 300~1200rad / min. The secondary treatment requires the primary treatment to be performed first.

[0026] In step 4), the heat treatment reaction conditions are as follows: the reaction temperature is 800~1800℃, the final temperature holding time is 1~12h, the nitrogen flow rate is 300~1200ml / min under nitrogen protection, and the heating rate is 1~10℃ / min.

[0027] In step 4), the obtained silicon-carbon anode material has an initial discharge specific capacity ≥450mAh / g, an initial coulombic efficiency ≥90%, a capacity retention rate ≥85% after 400 cycles, and a volume expansion rate ≤200%.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1) This invention obtains an amorphous porous conductive carbon skeleton by processing the raw oil through a series of processes. Then, a silicon-carbon coating agent is used to composite the conductive carbon skeleton, which allows silicon powder particles to penetrate into the interior of the conductive carbon skeleton. At the same time, a solvent evaporation coating method is used to form a complete, uniform, and dense coating layer, which increases the overall mechanical strength of the material and maintains the integrity of the electrode structure. This effectively solves the problems of high expansion rate, short safe service life, and poor cycle stability of silicon-carbon anode materials.

[0030] 2) This invention can control the structural parameters such as pore volume, porosity and interlayer spacing of conductive carbon skeleton through one or more combined processes such as pressure filtration and surface modification, and optimize the bulk density and energy density of silicon-carbon anode materials; through primary or secondary coating treatment, the coating layer thickness of silicon-carbon anode materials can be controlled, and the isotropy and rate performance of silicon-carbon anode materials can be further optimized.

[0031] 3) The silicon-carbon anode material prepared by the method of the present invention has an initial discharge specific capacity ≥450mAh / g, an initial coulombic efficiency ≥90%, a capacity retention rate ≥85% after 400 cycles, and a volume expansion rate ≤200%. Attached Figure Description

[0032] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0033] Figure 1 This is the charge-discharge curve of the silicon-carbon anode material of the present invention.

[0034] Figure 2 This is the cycling curve of the silicon-carbon anode material of the present invention. Detailed Implementation

[0035] The specific embodiments of the present invention will be further described below:

[0036] This invention provides a silicon-carbon anode material based on a conductive carbon framework and its preparation method, comprising the following steps:

[0037] 1) Raw coal is subjected to dry distillation to obtain raw coal gas; the raw coal gas is washed with ammonia water to obtain raw oil; the raw oil is subjected to super centrifugation to obtain centrifugal liquid and centrifugal residue;

[0038] 2) The centrifugal residue was subjected to pressure filtration, oxidation stabilization, surface modification and carbonization treatment in sequence to obtain conductive carbon skeleton A;

[0039] 3) The centrifuged liquid is distilled to remove the light components to obtain a heavy distillate, a silicon-carbon composite modifier is added, and the mixture is stirred to obtain silicon-carbon coating agent B;

[0040] 4) Conductive carbon skeleton A, silicon carbon coating agent B and solvent C are mixed in the liquid phase to obtain silicon carbon anode material precursor, and then subjected to ultrasonic vibration, high-speed shear emulsification, solvent evaporation coating and heat treatment to obtain silicon carbon anode material.

[0041] In step 1), the raw coal is any one or a mixture of two or more of bituminous coal, anthracite, and lignite; the dry distillation conditions are a furnace top space temperature of 880~1100℃; the raw oil specifications are: ash content <0.05%, moisture content <1.0%, and quinoline insoluble content ≥15%; quinoline insolubles include primary organic quinoline insolubles and secondary quinoline insolubles, wherein the content of primary organic quinoline insolubles is ≥10%, ash content is <0.05%, and particle size distribution is D. 50 : 0.5~1μm, D max : 1.5~2μm; secondary quinoline insoluble content ≥5%, ash content <0.05%, particle size distribution is D 50 5~30μm, D max : 40~50μm; the content of toluene-insoluble matter in the centrifuged residue is ≥80%, and the ash content is <0.05%.

[0042] In step 1), the conditions for supercentrifugation are: separation temperature 30~80℃, separation time 0.5~5h, centrifugation speed 5000~20000rad / min, and sieve mesh 100~800 mesh.

[0043] In step 2), the pressure filtration is performed once or multiple times. The extractant used in the first pressure filtration is any one or a mixture of two or more of the following: wash oil, pyridine, and quinoline. The reaction conditions are: extraction temperature 100~180℃, extraction time 1~8h, and sieve to obtain filter residue of 100~400 mesh. The mass ratio of extractant to centrifuged residue is (1~5):1.

[0044] Before performing secondary filtration, a primary filtration process is first performed. For the secondary filtration, the extractant is any one or a mixture of two or more of acetone, benzene, toluene, and xylene. The reaction conditions are: extraction temperature 40-80℃, extraction time 1-4h, sieve mesh size 200-800 mesh, and mass ratio of extractant to upper filter residue (0.2-2):1. For the third or higher filtration, the reaction conditions are the same as those for the primary or secondary filtration.

[0045] In step 2), the oxidation stabilization reaction conditions are: reaction temperature of 260~380℃, air flow rate of 1~10m3 / h, and treatment time of 1~8h.

[0046] Surface modification can be performed in one or more stages. The reaction conditions are as follows: reaction temperature 300–1200℃, modifier water, CO2, KOH, K2CO3, NaOH, or Na2CO3, and reaction time 0.5–10 hours. Multi-stage modification refers to performing multiple stages of the initial treatment. After each stage of treatment, testing is conducted. If the indicators fail to meet the requirements, a second or more stages of modification can be performed.

[0047] The carbonization reaction conditions are as follows: under nitrogen protection, the nitrogen flow rate is 300~1200 ml / min, the heating rate is 1~10℃ / min, the temperature is 700~1800℃, and the final temperature holding time is 1~12 h.

[0048] In step 3), the distillation reaction conditions are: bottom temperature of 160~280℃, vacuum degree of 0.01~0.09MPa; mass ratio of silicon-carbon composite modifier to heavy distillate (0.2~1):1.

[0049] The silicon-carbon composite modifier is composed of the following components by weight percentage: epoxy resin, silane coupling agent, and nano-silicon powder, in a mass ratio of (6~10):(2~4):(1~5), wherein the silicon powder particle size distribution is D. 10 : 2~5, D 50 : 20~40, D max 120~150μm.

[0050] In step 4), solvent C is any one of carbon tetrachloride, toluene, pyridine, quinoline, heavy oil, and wash oil; the mass ratio of conductive carbon skeleton A, silicon carbon coating agent B, and solvent C is: A:B:C = 1:(0.5~4):(0.5~8); the reaction conditions for liquid phase mixing are: liquid phase temperature of 60~240℃, stirring speed of 200~1200 rad / min, and stirring time of 1~8h.

[0051] In step 4), the ultrasonic vibration reaction conditions are: ultrasonic vibration temperature of 30~80℃ and time of 0.5~6h; the high-speed shear emulsification reaction conditions are: emulsification temperature of 160~280℃, stirring speed of 800~2000rad / min and emulsification time of 0.5~4h.

[0052] In step 4), the solvent evaporation coating is either a primary or secondary process, selected based on the coating thickness and structural requirements. For secondary processing, primary processing must be performed first. The reaction conditions for primary processing are: evaporation temperature 260–380℃, vacuum degree 0.01–0.09 MPa, time 2–6 h, and rotation speed 60–300 rad / min. The reaction conditions for secondary processing are: reaction temperature 400–800℃, vacuum degree 0.01–0.09 MPa, time 2–6 h, and rotation speed 300–1200 rad / min.

[0053] In step 4), the heat treatment reaction conditions are as follows: the reaction temperature is 800~1800℃, the final temperature holding time is 1~12h, the nitrogen flow rate is 300~1200ml / min under nitrogen protection, and the heating rate is 1~10℃ / min.

[0054] In step 4), the obtained silicon-carbon anode material has an initial discharge specific capacity ≥450mAh / g, an initial coulombic efficiency ≥90%, a capacity retention rate ≥85% after 400 cycles, and a volume expansion rate ≤200%.

[0055] The following embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0056] Example:

[0057] Tables 1-1 and 1-2 show the preparation process parameters for obtaining the conductive carbon framework A in each embodiment. Table 2 shows the preparation process parameters for obtaining the silicon-carbon coating agent B in each embodiment. Table 3 shows the preparation process parameters for obtaining the silicon-carbon anode material in each embodiment.

[0058] QI refers to quinoline insolubles. TI refers to toluene insolubles.

[0059] Table 1-1 Preparation process parameters of conductive carbon framework A

[0060]

[0061] Table 1-2 Preparation process parameters of conductive carbon framework A

[0062]

[0063] Table 2 Preparation process parameters of silicon-carbon coating agent B

[0064]

[0065] Table 3. Preparation process parameters of silicon-carbon anode materials

[0066]

[0067] Therefore, and in combination Figure 1 and Figure 2 It is known that the silicon-carbon anode material based on a conductive carbon skeleton and its preparation method provided by the present invention have the following advantages: the initial discharge specific capacity ≥450mAh / g, the initial coulombic efficiency ≥90%, the capacity retention rate ≥85% after 400 cycles, and the volume expansion rate ≤200%. The silicon-carbon anode material has advantages such as low expansion rate, long safe service life, and good cycle stability.

[0068] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention. Furthermore, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. In addition, various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of the present invention, they should also be considered as the content disclosed by the present invention.

Claims

1. A method for preparing silicon-carbon anode material based on a conductive carbon framework, characterized in that, Includes the following steps: 1) Raw coal is subjected to dry distillation to obtain raw coal gas; the raw coal gas is washed with ammonia water to obtain raw oil; the raw oil is subjected to super centrifugation to obtain centrifugal liquid and centrifugal residue; 2) The centrifuged residue was subjected to pressure filtration, oxidation stabilization, surface modification, and carbonization treatment in sequence to obtain conductive carbon skeleton A; 3) The centrifuged liquid is distilled to remove the light components to obtain a heavy distillate, a silicon-carbon composite modifier is added, and the mixture is stirred to obtain silicon-carbon coating agent B; 4) Conductive carbon skeleton A, silicon carbon coating agent B and solvent C are mixed in the liquid phase to obtain silicon carbon anode material precursor, and then subjected to ultrasonic vibration, high-speed shear emulsification, solvent evaporation coating and heat treatment to obtain silicon carbon anode material. In step 3), the distillation reaction conditions are: bottom temperature of 160~280℃, vacuum degree of 0.01~0.09MPa; mass ratio of silicon-carbon composite modifier to heavy distillate (0.2~1):

1. The silicon-carbon composite modifier is composed of the following components by weight percentage: epoxy resin, silane coupling agent, and nano-silicon powder, in a mass ratio of (6~10):(2~4):(1~5), and the silicon powder particle size distribution is D. 10 : 2~5, D 50 : 20~40, D max : 120~150μm; In step 4), solvent C is any one of carbon tetrachloride, toluene, pyridine, quinoline, heavy oil, and wash oil; the mass ratio of conductive carbon skeleton A, silicon carbon coating agent B, and solvent C is: A:B:C = 1:(0.5~4):(0.5~8); the reaction conditions for liquid phase mixing are: liquid phase temperature of 60~240℃, stirring speed of 200~1200 rad / min, and stirring time of 1~8h. In step 1), the raw coal is any one or a mixture of two or more of bituminous coal, anthracite, and lignite; the dry distillation conditions are a furnace top space temperature of 880~1100℃; the raw oil specifications are: ash content <0.05%, moisture content <1.0%, and quinoline insoluble content ≥15%; quinoline insolubles include primary organic quinoline insolubles and secondary quinoline insolubles, wherein the content of primary organic quinoline insolubles is ≥10%, ash content is <0.05%, and particle size distribution is D. 50 : 0.5~1μm, D max : 1.5~2μm; secondary quinoline insoluble content ≥5%, ash content <0.05%, particle size distribution is D 50 5~30μm, D max : 40~50μm; the content of toluene-insoluble matter in the centrifuged residue is ≥80%, and the ash content is <0.05%.

2. The method for preparing silicon-carbon anode material based on a conductive carbon framework according to claim 1, characterized in that, In step 1), the conditions for supercentrifugation are: separation temperature 30~80℃, separation time 0.5~5h, centrifugation speed 5000~20000rad / min, and sieve mesh 100~800 mesh.

3. The method for preparing silicon-carbon anode material based on a conductive carbon framework according to claim 1, characterized in that, In step 2), the pressure filtration is performed once or multiple times. The extractant used in the first pressure filtration is any one or a mixture of two or more of the following: wash oil, pyridine, and quinoline. The reaction conditions are: extraction temperature 100~180℃, extraction time 1~8h, and sieve to obtain filter residue of 100~400 mesh. The mass ratio of extractant to centrifuged residue is (1~5):

1. Before performing secondary filtration, a primary filtration process is first performed. For the secondary filtration, the extractant is any one or a mixture of two or more of acetone, benzene, toluene, and xylene. The reaction conditions are: extraction temperature 40-80℃, extraction time 1-4h, sieve mesh size 200-800 mesh, and mass ratio of extractant to upper filter residue (0.2-2):

1. For the third or higher filtration, the reaction conditions are the same as those for the primary or secondary filtration.

4. The method for preparing silicon-carbon anode material based on a conductive carbon framework according to claim 1, characterized in that, In step 2), the oxidation stabilization reaction conditions are: a reaction temperature of 260~380℃ and an air flow rate of 1~10 m³ / h. 3 / h, processing time 1~8h; Surface modification is a one-stage or multi-stage treatment. The reaction conditions are as follows: reaction temperature is 300~1200℃, modifier is water, CO2, KOH, K2CO3, NaOH, or Na2CO3, and reaction time is 0.5~10h. The carbonization reaction conditions are as follows: under nitrogen protection, the nitrogen flow rate is 300~1200 ml / min, the heating rate is 1~10℃ / min, the temperature is 700~1800℃, and the final temperature holding time is 1~12 h.

5. The method for preparing silicon-carbon anode material based on a conductive carbon framework according to claim 1, characterized in that, In step 4), the ultrasonic vibration reaction conditions are: ultrasonic vibration temperature of 30~80℃ and time of 0.5~6h; the high-speed shear emulsification reaction conditions are: emulsification temperature of 160~280℃, stirring speed of 800~2000rad / min and emulsification time of 0.5~4h.

6. The method for preparing silicon-carbon anode material based on a conductive carbon framework according to claim 1, characterized in that, In step 4), solvent evaporation coating is either a primary or secondary process. The primary process has the following reaction conditions: evaporation temperature of 260–380°C, vacuum degree of 0.01–0.09 MPa, time of 2–6 h, and rotation speed of 60–300 rad / min. The secondary process has the following reaction conditions: reaction temperature of 400–800°C, vacuum degree of 0.01–0.09 MPa, time of 2–6 h, and rotation speed of 300–1200 rad / min. The primary process must be performed before the secondary process can be carried out. In step 4), the heat treatment reaction conditions are as follows: the reaction temperature is 800~1800℃, the final temperature holding time is 1~12h, the nitrogen flow rate is 300~1200ml / min under nitrogen protection, and the heating rate is 1~10℃ / min.

7. A silicon-carbon anode material prepared by the method for preparing a silicon-carbon anode material based on a conductive carbon framework as described in any one of claims 1-6, characterized in that, First discharge specific capacity ≥450mAh / g, first coulombic efficiency ≥90%, capacity retention ≥85% after 400 cycles, and volume expansion ≤200%.

Images