Silicon-carbon negative electrode material based on organic silicon waste silicon powder and preparation method and application thereof

Abstract

The application belongs to the technical field of lithium ion batteries, and discloses a silicon-carbon negative electrode material based on organic silicon waste silicon powder and a preparation method and application thereof.The preparation method comprises the following steps: subjecting the organic silicon waste silicon powder to rapid annealing treatment; mixing the waste silicon powder after the rapid annealing treatment with an acid solution, performing acid immersion, and obtaining modified waste silicon powder; subjecting the modified waste silicon powder to mechanical grinding, and obtaining modified waste silicon powder abrasive; mixing the modified waste silicon powder abrasive, an organic carbon source and a solvent, performing spray granulation on the obtained precursor solution, and obtaining silicon-carbon microspheres; introducing a carbon deposition precursor source, and performing carbon deposition on the silicon-carbon microspheres, and obtaining a silicon-carbon negative electrode material.The application realizes the development of a new type of silicon-carbon negative electrode material with high tap density, and provides a new idea and new path for the value-added recycling of difficult-to-treat organic silicon waste silicon powder in the organic silicon industry and the low-cost development of high-performance lithium ion silicon negative electrodes.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a silicon-carbon anode material based on organosilicon waste silicon powder, its preparation method and application. Background Technology

[0002] Organosilicon materials are a special type of polymer that possesses both organic and inorganic material structures. Due to the special structure of organosilicon materials, their production process is extremely complex. The basic production process generally includes the following steps: (1) reacting silicon powder with chloromethane to synthesize organosilicon monomers, where the silicon powder is currently available as metallic silicon that meets national production standards; (2) producing organosilicon intermediates from the chlorosilane monomers through pyrolysis or hydrolysis; (3) further processing the unreacted organosilicon monomers and the organosilicon intermediates produced in the previous step through different reaction processes to produce the desired product. Currently, the most effective and economical method for producing organosilicon monomers is to react chloromethane with silicon powder to generate methylchlorosilane under copper-based catalysts such as copper / copper chloride or oxide.

[0003] To ensure timely removal of heat released during the reaction, manufacturers typically use fluidized beds as the reaction equipment. To improve the utilization rate of silicon powder converted into organosilicon monomers in the fluidized bed reactor, a two-stage cyclone separator is usually installed at the downstream end of the fluidized bed reaction. The centrifugal separation action of the cyclone separator separates unreacted copper-based catalyst, chloromethane, coarse monomers, and fine silicon powder particles. However, during the cyclone separation process, a significant portion of finer silicon powder and copper-based catalyst still escapes with the gaseous coarse monomers and chloromethane, forming waste organosilicon powder. This waste organosilicon powder has a fine particle size and high copper content; if not effectively recycled, it will result in a significant waste of resources. Furthermore, the average particle size of the waste organosilicon powder is small, and because it contains organosilicon and fine copper powder, its activity is high, making it prone to oxidation or even combustion when exposed to air, posing a significant safety hazard when stored. More importantly, due to the fine particle size, complex composition, and large amount of impurities in the waste organosilicon powder, research progress on its effective recycling has been relatively slow. How to dispose of waste silicone powder generated during the production of silicone has become a huge challenge for the silicone industry. Summary of the Invention

[0004] The purpose of this invention is to provide a silicon-carbon anode material based on organosilicon waste silicon powder, its preparation method and application, to solve the problem of difficult disposal of organosilicon waste silicon powder generated during organosilicon production.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing silicon-carbon anode materials based on organosilicon waste silicon powder, comprising the following steps:

[0007] (1) Rapidly anneal the organosilicon waste silicon powder; mix the rapidly annealed waste silicon powder with an acid solution and acid leaching to obtain modified waste silicon powder;

[0008] (2) The modified waste silicon powder described in step (1) is mechanically ground to obtain modified waste silicon powder abrasive; the modified waste silicon powder abrasive, organic carbon source and solvent are mixed, and the resulting precursor solution is spray granulated to obtain silicon carbon microspheres;

[0009] (3) Introduce a carbon deposition precursor source and perform carbon deposition on the silicon-carbon microspheres described in step (2) to obtain silicon-carbon anode material;

[0010] In step (1), the waste silicone powder contains elemental silicon, copper and residual silicone.

[0011] In step (1), the temperature of the rapid annealing treatment is 200 to 1500°C, the holding time of the rapid annealing treatment is 0.1 h to 20 h, and the number of rapid annealing treatments is 1 to 5.

[0012] Preferably, in the method for preparing silicon-carbon anode material based on organosilicon waste silicon powder, in step (1), the atmosphere of the rapid annealing treatment is air, argon or nitrogen, the gas flow rate of the rapid annealing treatment is 10-600 mL / min, and the heating rate to the temperature of the rapid annealing treatment is 20-500 °C / min.

[0013] Preferably, in the method for preparing silicon-carbon anode material based on organosilicon waste silicon powder, in step (1), the acid in the acid solution is one or more of hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid, and the concentration of the acid in the acid solution is 0.01-5 mol / L; the liquid-solid ratio of the acid solution to the waste silicon powder after rapid annealing is ≥3 mL:1 g; the acid leaching temperature is 0-80℃, and the acid leaching time is 0.01-20 h.

[0014] Preferably, in the method for preparing silicon-carbon anode material based on organosilicon waste silicon powder, in step (1), the acid solution further includes an oxidant; the oxidant is H2O2, Fe(NO3)3, KMnO4, KBrO3, K2Cr2O7 or Na2S2O8, and the concentration of the oxidant in the acid solution is 0-10 mol / L.

[0015] Preferably, in the method for preparing silicon-carbon anode material based on organosilicon waste silicon powder, in step (2), the modified waste silicon powder is mixed with carbon material and then mechanically ground; the carbon material is one or more of carbon fiber, mesophase carbon microspheres, graphite, hard carbon, porous activated carbon, carbon nanotubes, graphene and pitch, and the mass of the carbon material is 0 to 100 wt% of the mass of the modified waste silicon powder.

[0016] Preferably, in the method for preparing silicon-carbon anode material based on organosilicon waste silicon powder, in step (2), the organic carbon source includes one or more of glucose, phenolic resin, polydopamine and citric acid, the mass of the organic carbon source is 1 to 60 wt% of the mass of the modified waste silicon powder abrasive, the solid content of the precursor solution is 1 to 30 wt%, the atmosphere used for spray granulation is air, argon or nitrogen, the feed rate of spray granulation is 1 to 120 mL / min, the air inlet rate of spray granulation is 0.01 to 200 mL / min, and the temperature of spray granulation is 80 to 350 °C.

[0017] Preferably, in the method for preparing silicon-carbon anode material based on organosilicon waste silicon powder, in step (2), the precursor solution further includes a pore-forming agent; the pore-forming agent includes one or more of NaCl, MgCl2, LiCl, KCl, and CaCl2, and the mass of the pore-forming agent is 0 to 6 wt% of the mass of the modified waste silicon powder abrasive.

[0018] Preferably, in the method for preparing silicon-carbon anode material based on organosilicon waste silicon powder, in step (3), the carbon deposition precursor source is a mixture of active gas, hydrogen and argon; the active gas is methane, acetylene or carbon monoxide; the volume fraction of the active gas in the carbon deposition precursor source is 10-60%, the volume fraction of hydrogen in the carbon deposition precursor source is 10-50%, the volume fraction of argon in the carbon deposition precursor source is 10-50%; the gas flow rate of the carbon deposition precursor source is 0.1-100 mL / min, the carbon deposition temperature is 400-1300℃, and the carbon deposition time is 0.1-20 h.

[0019] The present invention also provides a silicon-carbon anode material prepared by the method for preparing silicon-carbon anode material based on organosilicon waste silicon powder.

[0020] The present invention also provides an application of the silicon-carbon anode material in lithium-ion batteries.

[0021] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0022] Based on the compositional characteristics of waste silicone powder, this invention first modifies the waste silicone powder through rapid annealing combined with selective acid leaching. Then, it refines the silicon material through mechanical grinding and homogenizes copper within the silicon. Combined with spray granulation, it obtains micron-sized silicon-carbon microspheres with a particle size distribution of 5–30 μm. Finally, using the catalytic effect of copper, a dense carbon layer is deposited on the surface of the silicon-carbon microspheres to obtain Si / C / Cu microspheres. The Si / C / Cu microspheres are dense and have high sphericity. Stacking them effectively increases the tap density of the material, thereby increasing its effective active material loading and effective capacity as a negative electrode material. This enables the development of a novel silicon-carbon negative electrode material with high tap density, providing a new approach and path for the value-added reuse of difficult-to-treat waste silicone powder in the silicone industry and the low-cost development of high-performance lithium-ion silicon negative electrodes.

[0023] This invention has the advantages of simple equipment requirements, easy operation, and suitability for large-scale industrial production. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0025] Figure 1 The morphology of the silicon-carbon anode material obtained in Example 1 is shown.

[0026] Figure 2 The morphology of the silicon-carbon anode material obtained in Example 2 is shown below.

[0027] Figure 3 The morphology of the silicon-carbon anode material obtained in Example 3 is shown below.

[0028] Figure 4 The morphology of the silicon-carbon anode material obtained in Example 4 is shown below.

[0029] Figure 5 The morphology of the silicon-carbon anode material obtained in Example 5 is shown. Detailed Implementation

[0030] This invention provides a method for preparing silicon-carbon anode materials based on organosilicon waste silicon powder, comprising the following steps:

[0031] (1) Rapidly anneal the organosilicon waste silicon powder; mix the rapidly annealed waste silicon powder with an acid solution and acid leaching to obtain modified waste silicon powder;

[0032] (2) The modified waste silicon powder described in step (1) is mechanically ground to obtain modified waste silicon powder abrasive; the modified waste silicon powder abrasive, organic carbon source and solvent are mixed, and the resulting precursor solution is spray granulated to obtain silicon carbon microspheres;

[0033] (3) Introduce a carbon deposition precursor source and perform carbon deposition on the silicon-carbon microspheres described in step (2) to obtain silicon-carbon anode material;

[0034] In step (1), the waste silicone powder contains elemental silicon, copper and residual silicone.

[0035] In step (1), the temperature of the rapid annealing treatment is 200 to 1500°C, the holding time of the rapid annealing treatment is 0.1 h to 20 h, and the number of rapid annealing treatments is 1 to 5.

[0036] In this invention, in step (1), the waste silicone powder contains elemental silicon, copper, and residual silicone. The content of elemental silicon is preferably 60–95 wt%, more preferably 88–93 wt%, and even more preferably 89.4–90.5 wt%. The content of residual silicone is preferably 0.1–20 wt%, more preferably 0.6–1.5 wt%, and even more preferably 0.8–1.1 wt%. The copper component exists in the waste silicone powder in the form of copper oxide and elemental copper. The content of copper is preferably 0.1–15 wt%, more preferably 6.2–10.5 wt%, and even more preferably 8.4–9.8 wt%.

[0037] In this invention, in step (1), the source of the organosilicon waste silicon powder is: a mixture formed by silicon powder and copper-based catalyst being discharged along with gaseous crude monomer and chloromethane during the synthesis of organosilicon monomer.

[0038] In this invention, in step (1), the atmosphere of the rapid annealing treatment is preferably air, argon or nitrogen, more preferably argon or nitrogen, and more preferably argon.

[0039] The gas flow rate for the rapid annealing treatment is preferably 10-600 mL / min, more preferably 100-600 mL / min, and even more preferably 300-400 mL / min;

[0040] The heating rate to the temperature of the rapid annealing treatment is preferably 20-500°C / min, more preferably 300-500°C / min, and even more preferably 300-400°C / min;

[0041] The rapid annealing temperature is 200–1500℃, preferably 600–1500℃, and more preferably 600–1000℃;

[0042] The holding time for the rapid annealing treatment is 0.1h to 20h, preferably 0.1h to 1h, and more preferably 0.1h to 0.5h;

[0043] The rapid annealing process is performed 1 to 5 times, preferably 1 to 3 times, and more preferably 1 time.

[0044] In this invention, the rapid annealing process serves to rapidly carbonize the organosilicon residue and regulate its carbon composition. When the rapid thermal annealing temperature exceeds 400°C, the amorphous carbon will be partially transformed into carbon nanotubes, graphene, and other nanomaterials.

[0045] In this invention, the rapid annealing process described in step (1) preferably further includes: natural cooling to 15-25°C (room temperature), with the rapid annealing atmosphere present during the cooling process.

[0046] In this invention, in step (1), the acid in the acid solution is preferably one or more of hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid, more preferably one or more of hydrochloric acid, nitric acid and hydrofluoric acid, and even more preferably hydrofluoric acid.

[0047] In this invention, the acid solution preferably contains two or more acids, and the ratio of different acids is not limited and can be adjusted as needed.

[0048] In this invention, in step (1), the concentration of acid in the acid solution is preferably 0.01 to 5 mol / L, more preferably 1 to 3 mol / L, and even more preferably 2 mol / L.

[0049] In this invention, in step (1), the liquid-to-solid ratio of the acid solution to the waste silicon powder after rapid annealing is preferably ≥3mL:1g, more preferably ≥5mL:1g, and even more preferably ≥8mL:1g.

[0050] In this invention, in step (1), the acid leaching temperature is preferably 0-80°C, more preferably 20-80°C, and even more preferably 60-80°C;

[0051] The acid leaching time is preferably 0.01 to 20 hours, more preferably 1 to 5 hours, and even more preferably 2 to 5 hours.

[0052] In this invention, in step (1), the acid solution preferably also includes an oxidizing agent.

[0053] In this invention, the oxidant is preferably H2O2, Fe(NO3)3, KMnO4, KBrO3, K2Cr2O7 or Na2S2O8, more preferably H2O2, KMnO4, K2Cr2O7 or Na2S2O8, and even more preferably H2O2.

[0054] In this invention, the concentration of the oxidant in the acid solution is preferably 0 to 10 mol / L, more preferably 4 to 10 mol / L, and even more preferably 4 mol / L.

[0055] In this invention, the purpose of acid leaching is to purify waste organosilicon powder. The purpose of adding an oxidant during acid leaching is to enhance the acid leaching purification process.

[0056] In this invention, step (1) preferably includes the following steps after acid leaching: sequential filtration, washing, and drying.

[0057] In this invention, the parameters for sequential filtration, washing, and drying are not limited, and any solution known to those skilled in the art can be used.

[0058] In this invention, in step (2), the mechanical grinding method is preferably ball milling or sand milling, and more preferably sand milling.

[0059] In this invention, in step (2), the rotational speed of the mechanical grinding is preferably ≥1000 r / min, more preferably ≥1200 r / min, and even more preferably ≥1500 r / min;

[0060] The mechanical grinding time is preferably ≥2h, more preferably ≥5h, and even more preferably ≥10h.

[0061] In this invention, in step (2), the modified waste silicon powder is mixed with carbon material and then mechanically ground.

[0062] In this invention, the carbon material is preferably one or more of carbon fiber, mesophase carbon microspheres, graphite, hard carbon, porous activated carbon, carbon nanotubes, graphene and pitch, more preferably one or more of mesophase carbon microspheres, graphite, carbon nanotubes and pitch, and even more preferably one or two of graphite and carbon nanotubes.

[0063] In this invention, it is preferred that there are two or more types of carbon materials. The ratio of different carbon materials is not limited and can be adjusted as needed.

[0064] In this invention, the source of the carbon material is not limited, and commercially available products well known to those skilled in the art can be used.

[0065] In this invention, the mass of the carbon material is preferably 0-100 wt% of the mass of the modified waste silicon powder, more preferably 20-80 wt%, and even more preferably 60-70 wt%.

[0066] In this invention, in step (2), the average particle size of the modified waste silicon powder abrasive is preferably 0.05-6 μm, more preferably 0.05-0.3 μm, and even more preferably 0.05-0.1 μm.

[0067] In this invention, in step (2), the organic carbon source preferably includes one or more of glucose, phenolic resin, polydopamine and citric acid, more preferably one or more of glucose, phenolic resin and citric acid, and even more preferably one or two of glucose and citric acid.

[0068] In this invention, it is preferred that there are two or more organic carbon sources. The ratio of different organic carbon sources is not limited and can be adjusted as needed.

[0069] In this invention, the source of the organic carbon source is not limited, and commercially available products well known to those skilled in the art can be used.

[0070] In this invention, in step (2), the mass of the organic carbon source is preferably 1 to 60 wt% of the mass of the modified waste silicon powder abrasive, more preferably 10 to 50 wt%, and even more preferably 40 to 50 wt%.

[0071] In this invention, in step (2), the solvent is preferably water or alcohol, and more preferably alcohol.

[0072] In this invention, the alcohol is preferably ethanol, methanol or ethylene glycol, more preferably ethanol or ethylene glycol, and even more preferably ethanol.

[0073] In this invention, in step (2), the precursor solution preferably also includes a pore-forming agent.

[0074] In this invention, the pore-forming agent preferably includes one or more of NaCl, MgCl2, LiCl, KCl and CaCl2, more preferably one or more of NaCl, MgCl2 and CaCl2, and more preferably NaCl.

[0075] In this invention, it is preferred that there are two or more pore-forming agents. The ratio of different pore-forming agents is not limited and can be adjusted as needed.

[0076] In this invention, the mass of the pore-forming agent is preferably 0-6 wt% of the mass of the modified waste silicon powder abrasive, more preferably 1-6 wt%, and even more preferably 4-6 wt%.

[0077] In this invention, the addition of an organic carbon source serves to strengthen the connection between the silicon and carbon components in the silicon-carbon microspheres and to provide a carbon source. The addition of a pore-forming agent serves to create a porous structure inside the silicon-carbon microspheres.

[0078] In this invention, in step (2), the liquid solid content of the spray granulation material is preferably 1-30 wt%, more preferably 10-30 wt%, and even more preferably 20-30 wt%.

[0079] In this invention, in step (2), the atmosphere used for spray granulation is preferably air, argon or nitrogen, more preferably argon or nitrogen, and even more preferably argon.

[0080] In this invention, in step (2), the feed rate of the spray granulation is preferably 1 to 120 mL / min, more preferably 1 to 10 mL / min, and even more preferably 5 to 10 mL / min;

[0081] The air inlet velocity for spray granulation is preferably 0.01–200 mL / min, more preferably 1–200 mL / min, and even more preferably 100–200 mL / min;

[0082] The spray granulation temperature is preferably 80–350°C, more preferably 80–150°C, and even more preferably 110–150°C.

[0083] In this invention, in step (3), the carbon deposition precursor source is preferably a mixture of active gas, hydrogen and argon.

[0084] In this invention, the active gas is preferably methane, acetylene, or carbon monoxide, more preferably methane or acetylene, and even more preferably acetylene.

[0085] In this invention, the volume fraction of the active gas in the carbon deposition precursor source is preferably 10-60%, more preferably 30-60%, and even more preferably 40-50%.

[0086] The volume fraction of hydrogen in the carbon deposition precursor source is preferably 10-50%, more preferably 30-50%, and even more preferably 30-40%.

[0087] The volume fraction of argon gas in the carbon deposition precursor source is preferably 10-50%, more preferably 10-40%, and even more preferably 10-30%.

[0088] In this invention, the volume fraction of the raw material in the carbon deposition precursor source is preferably measured under standard conditions.

[0089] In this invention, in step (3), the gas flow rate of the carbon deposition precursor source is preferably 0.1 to 100 mL / min, more preferably 0.1 to 80 mL / min, and even more preferably 10 to 50 mL / min.

[0090] In this invention, in step (3), the temperature of carbon deposition is preferably 400-1300°C, more preferably 600-1100°C, and even more preferably 600-800°C;

[0091] The carbon deposition time is preferably 0.1 to 20 hours, more preferably 1 to 20 hours, and even more preferably 1 to 2 hours.

[0092] The present invention also provides a silicon-carbon anode material prepared by the method for preparing silicon-carbon anode material based on organosilicon waste silicon powder.

[0093] The present invention also provides an application of the silicon-carbon anode material in lithium-ion batteries.

[0094] In this invention, the method of application is not limited, and any solution known to those skilled in the art can be used.

[0095] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0096] Example 1

[0097] This embodiment provides a method for preparing silicon-carbon anode materials based on organosilicon waste silicon powder, including the following steps:

[0098] (1) The organosilicon waste silicon powder contains 89.8 wt% elemental silicon, 9.1 wt% copper and 1.1 wt% organosilicon residue. The organosilicon waste silicon powder is subjected to one rapid annealing treatment under an argon atmosphere with an argon flow rate of 100 mL / min and a heating rate of 20 °C / min to the annealing temperature of 200 °C, and held at that temperature for 20 h. After annealing, it is naturally cooled to 20 °C along with the furnace temperature, with argon gas accompanying the cooling process. Then, the waste silicon powder after rapid annealing is acid-leached in a hydrofluoric acid-H2O2 mixed solution (hydrofluoric acid concentration of 1 mol / L and H2O2 concentration of 4 mol / L). The liquid-solid ratio of the mixed solution to the waste silicon powder after rapid annealing is 5 mL:1 g. The mixture is stirred and leached at 80 °C for 1 h. After acid leaching, it is filtered, washed and dried to obtain modified waste silicon powder.

[0099] (2) The modified waste silicon powder from step (1) and graphite were subjected to high-energy ball milling. The ball milling conditions were 1000 r / min and 5 h. The mass of graphite was 80 wt% of the mass of the modified waste silicon powder, and a modified waste silicon powder abrasive with an average particle size of 0.1 μm was obtained. The modified waste silicon powder abrasive, glucose, NaCl and ethanol were mixed. The mass of glucose was 20 wt% of the mass of the modified waste silicon powder abrasive, and the mass of NaCl was 1 wt% of the mass of the modified waste silicon powder abrasive, and a precursor solution with a solid content of 10 wt% was obtained. Argon gas was introduced, and the precursor solution was spray granulated at a feed rate of 10 mL / min, an inlet gas rate of 1 mL / min and a temperature of 110 °C. The precursor solution was self-assembled to obtain high sphericity silicon carbon microspheres with an average particle size of 12 μm.

[0100] (3) A carbon deposition precursor source with a gas flow rate of 0.1 mL / min was introduced. The carbon deposition precursor source (by volume fraction) was a mixture of 60% methane, 10% hydrogen, and 30% argon. Carbon deposition was carried out on the silicon-carbon microspheres described in step (2) at 600°C for 20 h to obtain a highly dense silicon-carbon anode material with the morphology shown in the figure. Figure 1 As shown, this indicates that it exhibits high sphericity.

[0101] The tap density was tested according to the national standard GB / T 24533-2019. The test results showed that the tap density of the silicon-carbon anode material obtained in Example 1 was as high as 0.95 g / cm³. 3 .

[0102] The silicon-carbon anode material obtained in Example 1 was subjected to electrochemical performance testing. The testing method was carried out in Appendix D of the national standard GB / T38823-2020. The results showed that its initial discharge capacity as an anode material could reach 1645 mAh / g.

[0103] Example 2

[0104] This embodiment provides a method for preparing silicon-carbon anode materials based on organosilicon waste silicon powder, including the following steps:

[0105] (1) The organosilicon waste silicon powder contains 93wt% elemental silicon, 6.2wt% copper and 0.8wt% organosilicon residue. The organosilicon waste silicon powder is subjected to one rapid annealing treatment in an air atmosphere with an air flow rate of 10mL / min and a heating rate of 500℃ / min to the annealing temperature of 1000℃, and held at that temperature for 0.1h. After annealing, it is naturally cooled to 20℃ along with the furnace temperature, with air accompanying the cooling process. Then, the waste silicon powder after rapid annealing is acid-leached in a hydrofluoric acid solution (hydrofluoric acid concentration 5mol / L) with a liquid-to-solid ratio of 10mL:1g. The leaching is stirred at 0℃ for 5h. After acid leaching, it is filtered, washed and dried to obtain modified waste silicon powder.

[0106] (2) The modified waste silicon powder from step (1) was subjected to high-energy ball milling with mesophase carbon microspheres. The ball milling conditions were 1200 r / min and 10 h. The mass of the mesophase carbon microspheres was 60 wt% of the mass of the modified waste silicon powder, resulting in modified waste silicon powder abrasive with an average particle size of 0.3 μm. The modified waste silicon powder abrasive, citric acid and water were mixed. The mass of the citric acid was 10 wt% of the mass of the modified waste silicon powder abrasive, resulting in a precursor solution with a solid content of 5 wt%. Argon gas was introduced, and the precursor solution was spray-granulated at a feed rate of 1 mL / min, an inlet gas rate of 0.01 mL / min and a temperature of 350°C. The precursor solution was self-assembled to obtain high sphericity silicon carbon microspheres with an average particle size of 10 μm.

[0107] (3) A carbon deposition precursor source with a gas flow rate of 10 mL / min was introduced. The carbon deposition precursor source (by volume fraction) was a mixture of 40% acetylene, 50% hydrogen, and 10% argon. Carbon deposition was carried out on the silicon-carbon microspheres described in step (2) at 800°C for 1 hour to obtain a highly dense silicon-carbon anode material with the morphology shown in the figure. Figure 2 As shown, this indicates that it has good sphericity and a smooth, dense surface.

[0108] The tap density was tested using the method of Example 1. The test results showed that the tap density of the silicon-carbon anode material obtained in Example 2 was as high as 0.93 g / cm³. 3 .

[0109] The electrochemical performance of the silicon-carbon anode material obtained in Example 2 was tested using the electrochemical performance testing method of Example 1. The results showed that its initial discharge capacity as an anode material could reach 2002 mAh / g.

[0110] Example 3

[0111] This embodiment provides a method for preparing silicon-carbon anode materials based on organosilicon waste silicon powder, including the following steps:

[0112] (1) The organosilicon waste silicon powder contains 90.5 wt% elemental silicon, 8.4 wt% copper and 1.1 wt% organosilicon residue. The organosilicon waste silicon powder was subjected to two rapid annealing treatments under a nitrogen atmosphere. The nitrogen flow rate was 600 mL / min, and the temperature was raised to 1000℃ at a heating rate of 300℃ / min and held for 0.5 h. After annealing, the powder was naturally cooled to 20℃ along with the furnace temperature, with nitrogen gas present during the cooling process. Then, the rapidly annealed waste silicon powder was acid-leached in a nitric acid solution (nitric acid concentration 3 mol / L). The liquid-solid ratio of the nitric acid solution to the rapidly annealed waste silicon powder was 3 mL:1 g. The leaching was carried out at 80℃ with stirring for 1 h. After acid leaching, the powder was filtered, washed and dried to obtain modified waste silicon powder.

[0113] (2) The modified waste silicon powder from step (1) was milled with graphite and carbon nanotubes under the following conditions: rotation speed 1500 r / min and time 5 h; the mass of graphite was 60 wt% of the mass of modified waste silicon powder and the mass of carbon nanotubes was 10 wt% of the mass of modified waste silicon powder, resulting in modified waste silicon powder abrasive with an average particle size of 0.1 μm; the modified waste silicon powder abrasive, phenolic resin, MgCl2 and ethanol were mixed, the mass of phenolic resin was 20 wt% of the mass of modified waste silicon powder abrasive and the mass of MgCl2 was 1 wt% of the mass of modified waste silicon powder abrasive, resulting in a precursor solution with a solid content of 20 wt%; argon gas was introduced, and the precursor solution was spray-granulated at a feed rate of 5 mL / min, an inlet gas rate of 200 mL / min and a temperature of 110 °C, and self-assembled to obtain high sphericity silicon carbon microspheres with an average particle size of 8 μm;

[0114] (3) A carbon deposition precursor source with a gas flow rate of 50 mL / min was introduced. The carbon deposition precursor source (by volume fraction) was a mixture of 50% carbon monoxide, 40% hydrogen, and 10% argon. Carbon deposition was carried out on the silicon-carbon microspheres described in step (2) at 700 °C for 2 hours to obtain a highly dense silicon-carbon anode material with the morphology shown in the figure. Figure 3 As shown, this indicates that it exhibits high sphericity.

[0115] The tap density was tested using the method described in Example 1. The test results showed that the tap density of the silicon-carbon anode material obtained in Example 3 was as high as 0.89 g / cm³. 3 .

[0116] The electrochemical performance of the silicon-carbon anode material obtained in Example 3 was tested using the electrochemical performance testing method of Example 1. The results showed that its initial discharge capacity as an anode material could reach 1986 mAh / g.

[0117] Example 4

[0118] This embodiment provides a method for preparing silicon-carbon anode materials based on organosilicon waste silicon powder, including the following steps:

[0119] (1) The organosilicon waste silicon powder contains 88wt% elemental silicon, 10.5wt% copper and 1.5wt% organosilicon residue. The organosilicon waste silicon powder is subjected to one rapid annealing treatment under a nitrogen atmosphere. The nitrogen flow rate is 300mL / min, and the temperature is raised to the annealing temperature of 1500℃ at a heating rate of 500℃ / min and held for 0.2h. After annealing, it is naturally cooled to 20℃ along with the furnace temperature, accompanied by nitrogen during the cooling process. Then, the waste silicon powder after rapid annealing is acid-leached in a hydrochloric acid-H2O2 mixed solution (hydrochloric acid concentration 2mol / L, H2O2 concentration 10mol / L). The liquid-solid ratio of the mixed solution to the waste silicon powder after rapid annealing is 8mL:1g. The mixture is stirred and leached at 60℃ for 5h. After acid leaching, it is filtered, washed and dried to obtain modified waste silicon powder.

[0120] (2) The modified waste silicon powder from step (1) and asphalt were sand-milled under the following conditions: rotation speed 1300 r / min and time 10 h; the mass of asphalt was 20 wt% of the mass of modified waste silicon powder, and modified waste silicon powder abrasive with an average particle size of 0.1 μm was obtained; the modified waste silicon powder abrasive, glucose, NaCl and water were mixed, the mass of glucose was 60 wt% of the mass of modified waste silicon powder abrasive, and the mass of NaCl was 6 wt% of the mass of modified waste silicon powder abrasive, and a precursor solution with a solid content of 30 wt% was obtained; argon gas was introduced, and the precursor solution was spray-granulated at a feed rate of 1 mL / min, an air inlet rate of 200 mL / min and a temperature of 150 °C, and self-assembled to obtain high sphericity silicon carbon microspheres with an average particle size of 25 μm;

[0121] (3) A carbon deposition precursor source with a gas flow rate of 80 mL / min was introduced. The carbon deposition precursor source (by volume fraction) was a mixture of 10% methane, 40% hydrogen, and 50% argon. Carbon deposition was carried out on the silicon-carbon microspheres described in step (2) at 1000 °C for 1 h to obtain a silicon-carbon anode material with the morphology shown in the figure. Figure 4 As shown, the silicon-carbon composite material exhibits a porous internal structure and a dense external structure.

[0122] The tap density was tested using the method described in Example 1. The test results showed that the tap density of the silicon-carbon anode material obtained in Example 4 was as high as 1.10 g / cm³. 3 .

[0123] The electrochemical performance of the silicon-carbon anode material obtained in Example 4 was tested using the electrochemical performance testing method of Example 1. The results showed that its initial discharge capacity as an anode material could reach 2234 mAh / g.

[0124] Example 5

[0125] This embodiment provides a method for preparing silicon-carbon anode materials based on organosilicon waste silicon powder, including the following steps:

[0126] (1) The organosilicon waste silicon powder contains 89.4 wt% elemental silicon, 9.8 wt% copper and 0.6 wt% organosilicon residue. The organosilicon waste silicon powder is subjected to one rapid annealing treatment under an argon atmosphere with an argon flow rate of 400 mL / min and a heating rate of 300 °C / min to the annealing temperature of 600 °C, and held for 1 h. After annealing, it is naturally cooled to 20 °C along with the furnace temperature, with argon gas accompanying the cooling process. Then, the waste silicon powder after rapid annealing is acid-leached in a hydrofluoric acid-hydrochloric acid mixed solution (hydrofluoric acid concentration of 1 mol / L and hydrochloric acid concentration of 1 mol / L). The liquid-solid ratio of the mixed solution to the waste silicon powder after rapid annealing is 20 mL: 1 g. The mixture is stirred and leached at 20 °C for 2 h. After acid leaching, it is filtered, washed and dried to obtain modified waste silicon powder.

[0127] (2) The modified waste silicon powder from step (1) was milled under the following conditions: rotation speed 2000 r / min and time 20 h, to obtain modified waste silicon powder abrasive with an average particle size of 0.05 μm; the modified waste silicon powder abrasive, glucose, citric acid, CaCl2 and ethylene glycol were mixed, with the mass of glucose being 40 wt% of the mass of the modified waste silicon powder abrasive, the mass of citric acid being 20 wt% of the mass of the modified waste silicon powder abrasive, and the mass of CaCl2 being 4 wt% of the mass of the modified waste silicon powder abrasive, to obtain a precursor solution with a solid content of 10 wt%; argon gas was introduced, and the precursor solution was spray granulated at a feed rate of 120 mL / min, an inlet gas rate of 50 mL / min and a temperature of 80°C, to obtain high sphericity silicon carbon microspheres with an average particle size of about 15 μm by self-assembly;

[0128] (3) A carbon deposition precursor source with a gas flow rate of 10 mL / min was introduced. The carbon deposition precursor source (by volume fraction) was a mixture of 30% acetylene, 30% hydrogen, and 40% argon. Carbon deposition was carried out on the silicon-carbon microspheres described in step (2) at 1100℃ for 1 h to obtain a highly dense silicon-carbon anode material with the morphology shown in the figure. Figure 5 As shown, this indicates that it exhibits high sphericity and uniform distribution.

[0129] The tap density was tested using the method described in Example 1. The test results showed that the tap density of the silicon-carbon anode material obtained in Example 5 was as high as 0.88 g / cm³. 3 .

[0130] The electrochemical performance of the silicon-carbon anode material obtained in Example 5 was tested using the electrochemical performance testing method of Example 1. The results showed that its initial discharge capacity as an anode material could reach 2018 mAh / g.

[0131] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing silicon-carbon anode material based on organosilicon waste silicon powder, characterized in that, Includes the following steps: (1) Rapidly anneal the organosilicon waste silicon powder; mix the rapidly annealed waste silicon powder with an acid solution and acid leaching to obtain modified waste silicon powder; (2) The modified waste silicon powder described in step (1) is mechanically ground to obtain modified waste silicon powder abrasive; Modified waste silicon powder abrasive, organic carbon source and solvent are mixed, and the resulting precursor solution is spray granulated to obtain silicon-carbon microspheres; (3) Introduce a carbon deposition precursor source and perform carbon deposition on the silicon-carbon microspheres described in step (2) to obtain silicon-carbon anode material; In step (1), the waste silicone powder contains elemental silicon, copper and silicone residue; the source of the waste silicone powder is: a mixture formed by the discharge of silicon powder and copper catalyst along with gaseous crude monomer and chloromethane during the synthesis of silicone monomer; In step (1), the temperature of the rapid annealing treatment is 600~1500℃, the holding time of the rapid annealing treatment is 0.1h~1h, the number of rapid annealing treatments is 1~5 times, the atmosphere of the rapid annealing treatment is air, argon or nitrogen, the gas flow rate of the rapid annealing treatment is 10~600mL / min, and the heating rate to the rapid annealing treatment temperature is 20~500℃ / min; In step (1), the acid in the acid solution is one or more of hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid, and the concentration of the acid in the acid solution is 0.01~5 mol / L; the liquid-to-solid ratio of the acid solution to the waste silicon powder after rapid annealing is ≥3 mL:1 g; the acid leaching temperature is 0~80℃, and the acid leaching time is 0.01~20 h; In step (3), the carbon deposition precursor source is a mixture of active gas, hydrogen, and argon; the active gas is methane, acetylene, or carbon monoxide; the volume fraction of the active gas in the carbon deposition precursor source is 40-50%, the volume fraction of hydrogen in the carbon deposition precursor source is 30-40%, and the volume fraction of argon in the carbon deposition precursor source is 10-30%; the gas flow rate of the carbon deposition precursor source is 0.1-100 mL / min, the carbon deposition temperature is 400-1300℃, and the carbon deposition time is 0.1-20 h.

2. The method for preparing silicon-carbon anode material based on organosilicon waste silicon powder as described in claim 1, characterized in that, In step (1), the acid solution also includes an oxidant; the oxidant is H2O2, Fe(NO3)3, KMnO4, KBrO3, K2Cr2O7 or Na2S2O8, and the concentration of the oxidant in the acid solution is 0~10 mol / L.

3. The method for preparing silicon-carbon anode material based on organosilicon waste silicon powder as described in claim 1, characterized in that, In step (2), the modified waste silicon powder is mixed with carbon material and then mechanically ground; the carbon material is one or more of carbon fiber, mesophase carbon microspheres, graphite, hard carbon, porous activated carbon, carbon nanotubes, graphene and pitch, and the mass of the carbon material is 0 to 100 wt% of the mass of the modified waste silicon powder.

4. A method for preparing silicon-carbon anode material based on organosilicon waste silicon powder as described in claim 1 or 3, characterized in that, In step (2), the organic carbon source includes one or more of glucose, phenolic resin, polydopamine and citric acid, the mass of the organic carbon source is 1 to 60 wt% of the mass of the modified waste silicon powder abrasive, the solid content of the precursor solution is 1 to 30 wt%, the atmosphere used for spray granulation is air, argon or nitrogen, the feed rate of spray granulation is 1 to 120 mL / min, the air inlet rate of spray granulation is 0.01 to 200 mL / min, and the temperature of spray granulation is 80 to 350 °C.

5. The method for preparing silicon-carbon anode material based on organosilicon waste silicon powder as described in claim 4, characterized in that, In step (2), the precursor solution also includes a pore-forming agent; the pore-forming agent includes one or more of NaCl, MgCl2, LiCl, KCl, and CaCl2, and the mass of the pore-forming agent is 0 to 6 wt% of the mass of the modified waste silicon powder abrasive.

6. The silicon-carbon anode material prepared by the method for preparing silicon-carbon anode material based on organosilicon waste silicon powder according to any one of claims 1 to 5.

7. The application of the silicon-carbon anode material according to claim 6 in lithium-ion batteries.

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