CN110474032A - It is a kind of to be given up the silicon-carbon cathode material and preparation method thereof of silicon based on photovoltaic - Google Patents

Abstract

It is given up the silicon-carbon cathode material and preparation method thereof of silicon the present invention provides a kind of based on photovoltaic.The preparation method comprises the following steps: (1) crushing the useless silicon material of collection, is dried to obtain waste silicon powder；(2) waste silicon powder is placed in progress high temperature removal of impurities in inert atmosphere, obtains high-purity silicon powder after overpickling purifying and drying；(3) high-purity silicon powder is added in decentralized medium, obtains nano-silicon solution through high speed ball milling；(4) the nano-silicon solution is collected and is adjusted and contained admittedly, sand milling is uniformly mixed after organic carbon source, conductive agent and dispersing agent are added according to a certain percentage；(5) mixed solution is sprayed dry and calcined, finally obtain silicon-carbon cathode material.The effect of silicon-carbon cathode material head prepared by this method is high, good cycling stability, preparation method have cost advantage, it is easy to operate, be suitble to industrialization production.

Description

A silicon-carbon negative electrode material based on photovoltaic waste silicon and its preparation method

technical field

The invention relates to the field of battery materials, in particular to a silicon-carbon negative electrode material based on photovoltaic waste silicon and a preparation method thereof.

Background technique

With the rapid development of mobile electronic products and new energy vehicles, on the one hand, the market’s requirements for the energy density of lithium-ion batteries are also increasing. On the other hand, national policies are also vigorously promoting the development of high-energy-density batteries. The Power Battery Development Action Plan (2017) clearly states that the specific energy of a single lithium-ion power battery will exceed 300 Wh/kg by 2020. As the key material of lithium-ion batteries, the selection of anode materials plays a decisive role in the energy performance of batteries. The theoretical specific capacity of graphite, a traditional negative electrode material, is only 372 mAh/g, which cannot meet the requirements of high energy density lithium-ion batteries. The theoretical capacity of silicon is as high as 4200 mAh/g, more than ten times that of graphite. In order to achieve the goal of 300 Wh/kg, it is a consensus in the industry to match the material system of silicon-based negative electrodes with high-nickel positive electrodes.

Although silicon-based anode materials have broad application prospects, there are still technical barriers to breakthrough in the actual use of silicon materials. The main problems are: 1) The volume expansion after lithium intercalation reaches 320%, and the volume expansion will further lead to material Pulverization, electrode structure change and continuous formation of solid electrolyte (SEI) film; 2) intrinsically belongs to semiconductor material and has poor conductivity. Due to the limitations of the above-mentioned bottleneck problem, silicon materials cannot be used alone as negative electrode materials. At present, the main practice of battery material companies is to combine silicon with graphite, conductive agents and other carbon materials. The introduction of carbon materials can improve silicon carbon negative electrodes. conductivity. Nanoscale is an effective solution to the volume expansion problem of silicon. Studies have shown that when the silicon material is smaller than 150 nm in at least one dimension, it can effectively alleviate the problem of volume expansion and prevent the material from pulverizing and breaking.

At present, most of the battery-grade nano-silicon powders on the market are prepared by plasma and laser methods, mainly using SiH ₄ gas as the reaction raw material through vapor deposition. Although the nano-silicon powders prepared by this method have high purity and controllable particle size , but the high production cost seriously restricts the development of the downstream silicon carbon material industry. In recent years, the photovoltaic industry has developed rapidly. In 2018, the global polysilicon production reached 430,000 tons, of which my country's production accounted for more than 50%. During the processing of solar silicon wafers, high-purity crystalline silicon with a purity of 99.9999% will be cut into specific sizes and shapes. During this process, about 40% of high-purity crystalline silicon will become waste silicon blocks and mixed in cutting fluid Therefore, more than 100,000 tons of cutting waste silicon are produced in my country every year, and about 50% of the submicron waste silicon is discarded because it is difficult to reuse in the photovoltaic industry. Purifying and refining the sub-micron silicon produced in the cutting process of the photovoltaic industry to prepare battery-grade nano-silicon can not only achieve resource recovery and reuse, but also greatly reduce the production cost of nano-silicon, and promote the development of silicon-carbon anode materials and lithium-ion batteries. industry development.

Chinese patent CN104112850 provides a preparation method of lithium-ion battery anode materials based on silicon waste from the photovoltaic industry. The purified and modified micron or submicron silicon is simply mixed with graphite and applied after matching with a specific binder system. Anode materials in Li-ion batteries. The mixed use of silicon and graphite can alleviate the volume expansion of silicon to a certain extent and improve the conductivity of the composite material. However, when used as the negative electrode material of lithium-ion batteries, the particle size of silicon has not been reasonably controlled, and micron-sized silicon is still There is a large volume expansion, and at the same time, the uncoated silicon will directly contact the electrolyte, and the electrolyte will be continuously consumed as the SEI film grows. Chinese patent CN104701491 uses the waste silicon slurry in the silicon wafer production process as raw material, and prepares nano-silicon porous silicon through drying, pickling, ball milling and strong acid corrosion, and directly uses it as the negative electrode material of lithium-ion batteries. Nano-silicon porous silicon can alleviate the volume expansion of silicon to a certain extent, but the large amount of strong acid corrosion preparation method used in it will pollute the environment and is not suitable for large-scale production.

Contents of the invention

In view of the above technical problems, the present invention proposes a silicon-carbon anode material based on photovoltaic waste silicon and its preparation method. Using waste silicon mud in the photovoltaic industry as raw material, the production cost is effectively reduced, and the preparation process is simple, which is suitable for industrialization enlarge. Using step-by-step refinement, the particle size of silicon powder is controlled within a reasonable range, and the particle size and specific surface area are balanced, so that nano-silicon can exert better performance. In addition, the organic carbon source is introduced in the sanding process, and a stable and uniform amorphous carbon coating layer can be formed on the surface of the silicon material after high-temperature calcination, which prevents the direct contact between the silicon material and the electrolyte, which is conducive to the formation of a stable SEI film and improves Coulombic efficiency and cycle stability of materials.

In order to solve the problems of the technologies described above, the technical solution of the present invention is:

A silicon-carbon negative electrode material based on photovoltaic waste silicon. The silicon-carbon negative electrode material is a spherical silicon-carbon composite negative electrode material. The final sheet-shaped nano-silicon and conductive agent are composed; the sheet-shaped nano-silicon is obtained by processing the scraps generated when the photovoltaic industry cuts crystalline silicon sheets. The particle size of the sheet-shaped nano-silicon is 50-200 nm, and the thickness is 10~50nm; the mass proportion of each component is: flaky nano-silicon 50%~90%, conductive agent 5~20%, organic cracked carbon 10~30%.

The preparation method of the silicon carbon negative electrode material based on photovoltaic waste silicon comprises the following steps:

(1) Pulverize and dry photovoltaic waste silicon materials to obtain waste silicon powder, place the waste silicon powder in an inert atmosphere for high-temperature removal of impurities, and then obtain high-purity silicon powder after pickling and drying;

(2) Add high-purity silicon powder and zirconia balls to the solvent in a certain proportion, and obtain nano-silicon suspension after high-speed ball milling in an inert atmosphere;

(3) Collect the nano-silicon suspension and adjust the solid content, add an organic carbon source, a conductive agent and a dispersant, and then carry out sealing sand grinding to mix evenly to obtain a mixed slurry;

(4) The mixed slurry is spray-dried and calcined in an inert atmosphere to finally obtain a silicon-carbon anode material.

Further, the photovoltaic waste silicon in the step (1) is the waste silicon material produced when the diamond wire cuts solar crystalline silicon wafers, wherein the purity of the cut crystalline silicon is greater than 99.9999% or above, and the silicon content of the waste silicon material is greater than 80%.

Further, in the step (1), high-temperature calcination is first carried out to remove most of the organic impurities, and then pickling is carried out; the pickling includes two pickling purifications, firstly, one or more of dilute hydrochloric acid, dilute nitric acid and dilute sulfuric acid are used to pickling, and then pickling with hydrofluoric acid for the second time after cleaning, the temperature of the pickling is 20-95°C, and the pickling time is 0.5-24 h.

Further, during the high-speed ball milling in the step (2), the solvent is one or more of deionized water, ethanol, butanol, methanol, isopropanol, cyclohexanone, acetone, methyl ethyl ketone or cyclohexane, The solid content is 5~50%.

Further, during high-speed ball milling in the step (2), the mass ratio of high-purity silicon powder to zirconia balls is 10:(5-30), the particle size of zirconia is 0.1-3 mm, and the ball-milling speed is 100-800rpm.

Further, the organic carbon source in the step (3) is one or more of phenolic resin, epoxy resin, sucrose, starch, chitosan or glucose.

Further, the dispersant in the step (3) is one or more of polyvinylpyrrolidone, polyethyleneimine, sodium carboxymethylcellulose or sodium dodecylbenzenesulfonate.

Further, in the step (3), the solid content during sanding is 5-50%, the sanding speed is 1000-3000 rpm, and the sanding time is 0.5-10 h.

Further, the calcination in the step (4) is to heat the spray-dried material to 600-1000°C for 1-4 hours at a heating rate of 1-20°C/min, and the inert atmosphere is one of nitrogen, argon or hydrogen. species or several.

The beneficial effects of the present invention are:

(1) The present invention uses photovoltaic waste silicon as a raw material, and the waste silicon powder mixed in the cutting fluid produced when cutting silicon wafers is purified and refined, and then used to prepare silicon-carbon anode materials, which can realize the recycling of waste silicon Reuse is conducive to the development of circular economy.

(2) The silicon-carbon anode material prepared by the present invention has obvious cost advantages. The price of nano-silicon prepared by plasma method and laser method is too high, and its cost accounts for about 50% of the overall cost of silicon-carbon materials. In the invention, the nano-silicon solution can be obtained by treating the waste silicon through a simple process, so the cost can be greatly reduced. The silicon-carbon anode material can be obtained by mixing the nano-solution with a certain proportion of organic carbon source and conductive agent, drying and calcining, and omitting the step of drying the nano-silicon solution, which simplifies the process and further reduces the production cost.

(3) The wet ball milling refining process proposed by the present invention can control the particle size of silicon powder within a reasonable range, and finally obtain sheet-shaped nano-silicon with uniform particle size. The low specific surface area can be maintained, so the prepared sheet-like nano-silicon can maximize its electrochemical performance.

(4) The present invention proposes a spherical silicon-carbon anode material whose surface is uniformly coated with amorphous carbon. The organic carbon source and conductive agent are introduced during the sanding process. After the material is calcined, the amorphous carbon can be evenly coated on the surface of the sheet-shaped nano-silicon. The amorphous carbon layer can effectively prevent the direct contact between the silicon material and the electrolyte, which is conducive to the formation of a stable The SEI film improves the stability of the material; on the other hand, the addition of carbon materials and conductive agents can improve the overall conductivity of the material and improve the electrochemical performance of the material.

Description of drawings

Figure 1 is an SEM image of the silicon-carbon negative electrode material obtained in the present invention.

Fig. 2 is a cycle stability graph of the silicon-carbon negative electrode material obtained in the present invention.

Detailed ways

The present invention is further illustrated with the following examples, but the present invention is not limited to the following examples.

The experimental drugs and methods in the following examples were used according to conventional conditions or according to the product instructions.

The silicon-carbon anode material prepared by the invention was assembled into a half-cell and electrochemical performance test was carried out: silicon-carbon anode material: Super P: binder was homogenized and smeared according to the mass ratio of 8:1:1. Among them, the binder is: sodium carboxymethylcellulose (CMC): styrene-butadiene rubber (SBR): polyacrylic acid (PAA) solution with a mass ratio of 1:1:1, and the electrolyte is LiPF ₆ conventional electrolyte. The lithium sheet was used as the counter electrode and assembled into a CR2025 button cell. Under normal temperature conditions, the charge and discharge test was carried out at a current density of 100 mA/g using the LANHE CT2001A blue electric test system, and the voltage range was 0.005-2.0 V.

Example 1

The preparation method of the silicon-carbon anode material based on photovoltaic waste silicon in this embodiment, the steps are as follows:

(1) Use a pulverizer to pulverize photovoltaic waste silicon to an average particle size of less than 2 mm, and then dry it in a blast drying oven until the moisture content is less than 2%. The dried waste silicon powder was placed in a horizontal tube furnace, and heated to 900 °C at a rate of 5 °C/min under a nitrogen atmosphere for 2 h to remove impurities at high temperature.

(2) Immerse the silicon material after high temperature removal of impurities in 1 M dilute hydrochloric acid, stir at 40°C for 4 hours, filter, and wash with deionized water until neutral. Then carry out the second pickling, immerse the cleaned silicon material in 1 M hydrofluoric acid solution, stir at room temperature for 2 hours, filter again, and wash with deionized water until neutral. Then dry the cleaned silicon powder in a vacuum to obtain high-purity silicon powder with a purity greater than 99.5%.

(3) 50 g of high-purity silicon powder and 150 g of zirconia beads were weighed and added to 75 g of absolute ethanol, and the nano-silicon solution was obtained after ball milling at 300 rpm for 5 hours. Add absolute ethanol to the nano-silicon solution to adjust the solid content to 20%, then weigh 300 g of the nano-silicon solution, add 30 g of phenolic resin, 10 g of graphene and 20 g of polyethyleneimine to obtain a mixed slurry. The mixed slurry was poured into a sand mill and sanded for 3 h at 2000 rpm. Then the sand-milled slurry was spray-dried, calcined in a nitrogen atmosphere after drying, and the temperature was raised to 900°C at a rate of 5°C/min for 2 hours, and finally a silicon-carbon negative electrode material with a spherical microscopic morphology was obtained.

Example 2

The preparation method of the silicon-carbon anode material based on photovoltaic waste silicon in this embodiment, the steps are as follows:

(1) Use a pulverizer to pulverize photovoltaic waste silicon to an average particle size of less than 2 mm, and then dry it in a vacuum drying oven until the moisture content is less than 2%. The dried waste silicon powder was placed in a horizontal tube furnace, and heated to 700 °C at a rate of 5 °C/min under a nitrogen atmosphere for 2 h to remove impurities at high temperature.

(2) Immerse the silicon material after high-temperature removal of impurities in 1 M dilute nitric acid, stir at 70°C for 5 h, centrifuge, and wash repeatedly with deionized water until neutral. Then carry out the second pickling, immerse the cleaned silicon material in 0.5 M hydrofluoric acid solution, stir at room temperature for 10 hours, then centrifuge, and wash with deionized water until neutral. Then dry the cleaned silicon powder in a vacuum to obtain high-purity silicon powder with a purity greater than 99.5%.

(3) 50 g of high-purity silica powder and 80 g of zirconia beads were weighed and added to 80 g of deionized water, and the nano-silicon solution was obtained after ball milling at 400 rpm for 3 h. Add deionized water to the nano-silicon suspension to adjust the solid content to 20%, then weigh 300 g of the nano-silicon solution, add 35 g of glucose, 10 g of graphene, and 20 g of polyvinylpyrrolidone to obtain a mixed slurry. The mixed slurry was poured into a sand mill and sanded for 2 h at 2500 rpm. Then the sand-milled slurry was spray-dried, calcined in an argon atmosphere after drying, and heated at a rate of 5 °C/min to 700 °C for 2 h to obtain a silicon-carbon negative electrode material with a spherical microscopic morphology.

Example 3

The preparation method of the silicon-carbon anode material based on photovoltaic waste silicon in this embodiment, the steps are as follows:

(1) Use a pulverizer to pulverize photovoltaic waste silicon to an average particle size of less than 2 mm, and then dry it in a blast drying oven until the moisture content is less than 2%. The dried waste silicon powder was placed in a horizontal tube furnace, and heated to 700 °C at a rate of 5 °C/min under a nitrogen atmosphere for 2 h to remove impurities at high temperature.

(2) Immerse the silicon material after high-temperature removal of impurities in 2 M dilute sulfuric acid, stir at 60°C for 5 h, centrifuge, and wash repeatedly with deionized water until neutral. Then carry out the second pickling, immerse the cleaned silicon material in 1 M hydrofluoric acid solution, stir at room temperature for 5 hours, then centrifuge, and wash with deionized water until neutral. Then dry the cleaned silicon powder in a blast drying oven to obtain high-purity silicon powder with a purity greater than 99.5%.

(3) 50 g of high-purity silica powder and 150 g of zirconia beads were weighed and added to 50 g of acetone, and the nano-silicon solution was obtained after ball milling at 400 rpm for 3 h. Add acetone to the nano-silicon suspension to adjust the solid content to 50%, then weigh 200 g of the nano-silicon solution, add 50 g of epoxy resin, 10 g of carbon nanotubes and 40 g of carboxymethyl with a mass fraction of 30% After the sodium cellulose aqueous solution is obtained, the mixed slurry is obtained. The mixed slurry was poured into a sand mill and sanded for 1 h at 3000 rpm. Then the sand-milled slurry was spray-dried, calcined in a hydrogen atmosphere after drying, and heated to 900°C at a rate of 5°C/min for 2 hours to obtain a silicon-carbon negative electrode material with a spherical microscopic morphology.

Example 4

The preparation method of the silicon-carbon anode material based on photovoltaic waste silicon in this embodiment, the steps are as follows:

(1) Use a pulverizer to pulverize photovoltaic waste silicon to an average particle size of less than 2 mm, and then dry it in a blast drying oven until the moisture content is less than 2%. The dried waste silicon powder was placed in a horizontal tube furnace, and heated to 900 °C at a rate of 5 °C/min under a nitrogen atmosphere for 2 h to remove impurities at high temperature.

(2) Immerse the silicon material after high-temperature removal of impurities into a mixed solution of 2 M dilute sulfuric acid and dihydrochloric acid, stir at 70°C for 5 h, filter, and wash repeatedly with deionized water until neutral. Then carry out the second pickling, immerse the cleaned silicon material in 1 M hydrofluoric acid solution, stir at room temperature for 4 hours, then centrifuge, and wash with deionized water until neutral. Then dry the cleaned silicon powder in a blast drying oven to obtain high-purity silicon powder with a purity greater than 99.5%.

(3) 50 g of high-purity silicon powder and 120 g of zirconia beads were weighed and added to 50 g of methanol, and the nano-silicon solution was obtained after ball milling at 500 rpm for 2 hours. Next, 200 g of nano-silicon solution was weighed, and 50 g of sucrose, 5 g of carbon nanotubes, 5 g of graphene and 40 g of polyvinylpyrrolidone aqueous solution with a mass fraction of 30% were added respectively to obtain a mixed slurry. The mixed slurry was poured into a sand mill and sanded for 2 h at 2500 rpm. Then the sand-milled slurry was spray-dried, calcined in an argon atmosphere after drying, and heated to 900°C at a rate of 5°C/min for 2 hours to obtain a silicon-carbon negative electrode material with a spherical microscopic morphology.

Example 5

The preparation method of the silicon-carbon anode material based on photovoltaic waste silicon in this embodiment, the steps are as follows:

(1) Use a pulverizer to pulverize photovoltaic waste silicon to an average particle size of less than 2 mm, and then dry it in a blast drying oven until the moisture content is less than 2%. The dried waste silicon powder was placed in a horizontal tube furnace, and heated to 900 °C at a rate of 5 °C/min under a nitrogen atmosphere for 2 h to remove impurities at high temperature.

(2) Immerse the silicon material after high-temperature removal of impurities into a mixed solution of 2 M dilute nitric acid and dihydrochloric acid, stir at 50°C for 5 h, centrifuge, and wash repeatedly with deionized water until neutral. Then carry out the second pickling, immerse the cleaned silicon material in 1 M hydrofluoric acid solution, stir at room temperature for 4 h, then filter and wash with deionized water until neutral. Then dry the cleaned silicon powder in a drying oven to obtain high-purity silicon powder with a purity greater than 99.5%.

(3) 50 g of high-purity silica powder and 100 g of zirconia beads were weighed and added to a mixed solution of 80 g of ethanol and deionized water, and the nano-silicon solution was obtained after ball milling at 500 rpm for 2 h. Add deionized water to the nano-silicon solution to adjust the solid content to 30%, then weigh 200 g of the nano-silicon suspension, add 50 g of sucrose, 10 g of carbon nanotubes, 20 g of polyvinylpyrrolidone and 20 g of carboxymethyl The mixed slurry is obtained after base cellulose sodium. The mixed slurry was poured into a sand mill and sanded for 2.5 h at 3000 rpm. Then, the sand-milled slurry was spray-dried, calcined in a nitrogen atmosphere after drying, and heated to 850 °C at a rate of 5 °C/min for 2 h to obtain a silicon-carbon negative electrode material with a spherical microscopic morphology.

Example 6

The preparation method of the silicon-carbon anode material based on photovoltaic waste silicon in this embodiment, the steps are as follows:

(1) Use a pulverizer to pulverize photovoltaic waste silicon to an average particle size of less than 2 mm, and then dry it in a blast drying oven until the moisture content is less than 2%. The dried waste silicon powder was placed in a horizontal tube furnace, and heated to 850 °C at a rate of 5 °C/min under a nitrogen atmosphere for 2 h to remove impurities at high temperature.

(2) Immerse the silicon material after high-temperature removal of impurities into a mixed solution of 2 M dilute nitric acid and sulfuric acid, stir at room temperature for 10 h, filter, and wash repeatedly with deionized water until neutral. Then carry out the second pickling, immerse the cleaned silicon material in 0.5 M hydrofluoric acid solution, stir at room temperature for 12 hours, then centrifuge, and wash with deionized water until neutral. Then dry the cleaned silicon powder in a drying oven to obtain high-purity silicon powder with a purity greater than 99.5%.

(3) 50 g of high-purity silica powder and 150 g of zirconia beads were weighed and added to 80 g of acetone, and the nano-silicon solution was obtained after ball milling at 450 rpm for 2.5 h. Add deionized water to the nano-silicon solution to adjust the solid content to 10%, then weigh 600g of the nano-silicon suspension, add 50 g of glucose, 10 g of carbon nanotubes, 20 g of polyethyleneimine and 20 g of carboxymethyl The mixed slurry is obtained after base cellulose sodium. The mixed slurry was poured into a sand mill and sanded for 8 h at 1500 rpm. Then the sand-milled slurry was spray-dried, calcined in a nitrogen atmosphere after drying, and heated to 650°C at a rate of 5°C/min for 2 hours to obtain a silicon-carbon negative electrode material with a spherical microscopic morphology.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the present invention. within the scope of protection.

Claims (10)

1. A silicon-carbon negative electrode material based on photovoltaic waste silicon, characterized in that: the silicon-carbon negative electrode material is a spherical silicon-carbon composite negative electrode material, and the amorphous carbon formed by pyrolysis of organic matter is coated on the sheet-like nano-silicon The surface layer and the interior are composed of coated sheet-shaped nano-silicon and conductive agent; the sheet-shaped nano-silicon is obtained by processing the scraps generated when cutting crystalline silicon wafers in the photovoltaic industry, and the particle size of the sheet-shaped nano-silicon is 50 ~200 nm, thickness 10~50nm; the mass proportions of each component are: flake nano-silicon 50%~90%, conductive agent 5~20%, organic cracked carbon 10~30%. 2. the preparation method of the silicon-carbon anode material based on photovoltaic waste silicon according to claim 1, is characterized in that comprising the following steps: (1) Pulverize and dry photovoltaic waste silicon materials to obtain waste silicon powder, place the waste silicon powder in an inert atmosphere for high-temperature removal of impurities, and then obtain high-purity silicon powder after pickling and drying; (2) Add high-purity silicon powder and zirconia balls to the solvent in a certain proportion, and obtain nano-silicon suspension after high-speed ball milling in an inert atmosphere; (3) Collect the nano-silicon suspension and adjust the solid content, add an organic carbon source, a conductive agent and a dispersant, and then carry out sealing sand grinding to mix evenly to obtain a mixed slurry; (4) The mixed slurry is spray-dried and calcined in an inert atmosphere to finally obtain a silicon-carbon anode material. 3. The silicon-carbon anode material based on photovoltaic waste silicon and its preparation method according to claim 2, characterized in that: in the step (1), photovoltaic waste silicon is waste silicon produced when diamond wire cuts solar crystal silicon wafers Materials, wherein the purity of cut crystalline silicon is greater than 99.9999% or above, and the silicon content of waste silicon materials is greater than 80%. 4. The silicon-carbon anode material based on photovoltaic waste silicon and its preparation method according to claim 2, characterized in that: in the step (1), high-temperature calcination is first performed to remove most of the organic impurities, and then pickling is performed; Pickling includes two pickling purifications, first pickling with a mixture of one or more of dilute hydrochloric acid, dilute nitric acid and dilute sulfuric acid, and then performing a second pickling with hydrofluoric acid after cleaning, the pickling The temperature is 20~95℃, and the pickling time is 0.5~24 h. 5. The silicon-carbon anode material based on photovoltaic waste silicon and its preparation method according to claim 2, characterized in that: during the high-speed ball milling in the step (2), the solvent is deionized water, ethanol, butanol, methanol , isopropanol, cyclohexanone, acetone, methyl ethyl ketone or cyclohexane, and the solid content is 5~50%. 6. The silicon-carbon anode material based on photovoltaic waste silicon and its preparation method according to claim 2, characterized in that: during high-speed ball milling in the step (2), the mass ratio of high-purity silicon powder to zirconia balls is 10: (5~30), the particle size of zirconia is 0.1~3 mm, and the ball milling speed is 100-800rpm. 7. The silicon-carbon anode material based on photovoltaic waste silicon and its preparation method according to claim 2, characterized in that: the organic carbon source in the step (3) is phenolic resin, epoxy resin, sucrose, starch, One or more of chitosan or glucose. 8. The silicon-carbon anode material based on photovoltaic waste silicon and its preparation method according to claim 2, characterized in that: the dispersant in the step (3) is polyvinylpyrrolidone, polyethyleneimine, carboxymethyl One or more of sodium cellulose or sodium dodecylbenzenesulfonate. 9. The silicon-carbon anode material based on photovoltaic waste silicon and its preparation method according to claim 2, characterized in that: in the step (3), the solid content is 5-50% during sanding, and the sanding speed is 1000~ 3000 rpm, sanding time 0.5~10 h. 10. The silicon-carbon anode material based on photovoltaic waste silicon and its preparation method according to claim 2, characterized in that: the calcination in the step (4) is to spray-dry the material at 1-20°C/min The heating rate is raised to 600~1000℃ and kept for 1~4h, and the inert atmosphere is one or more of nitrogen, argon or hydrogen.