Nanometer silicon-based negative electrode material based on organic silicon waste contact body and preparation method and application of nanometer silicon-based negative electrode material

Abstract

The invention provides a nanometer silicon-based negative electrode material based on an organic silicon waste contact body and a preparation method and application thereof, and belongs to the technical field of lithium ion batteries. The method comprises the following steps: mixing the organic silicon waste contact with a non-oxidizing acid solution, and carrying out acid leaching to obtain silicon copper powder; the silicon-copper powder and a carbon source are mixed and then subjected to grinding and thermal plasma treatment in sequence, and the nanoscale silicon-copper / carbon composite material is obtained; and carrying out carbon coating treatment on the surface of the nanoscale silicon copper / carbon composite material through chemical vapor deposition by utilizing the catalytic action of copper to obtain the nanometer silicon-based negative electrode material. According to the method disclosed by the invention, resource recycling of the organic silicon waste contact body is realized, the problem of volume expansion of a silicon-based material in a charging and discharging process is effectively relieved, and meanwhile, the electron transmission efficiency of an electrode is remarkably improved due to high conductivity of copper; the nanometer silicon-based negative electrode material prepared by the invention has excellent cycling stability and relatively high capacity retention ratio.

Description

Technical Field

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

[0002] Organosilicon materials are a special class of polymers that possess both organic and inorganic structures. In organosilicon production, methylchlorosilane is the most important raw material. Among its many production methods, the direct method is widely used due to its simplicity, low cost, low risk, and ease of continuous scaling-up. Industrially, methylchlorosilane is prepared in a fluidized bed using silicon powder and chloromethane as raw materials, and copper powder or copper-based compounds as catalysts. However, after the fluidized bed has been running for a certain period, the reactivity of the silicon powder deteriorates due to the accumulation of carbon on the surface of the silicon powder particles and impurities. To avoid a decrease in yield, this portion of silicon powder needs to be discharged from the production system via airflow; the resulting powder is the waste catalyst. The main components of organosilicon waste catalyst are silicon powder (65-85 wt%), copper (5-15 wt%), metallic impurities (2-8 wt%), and residual organosilicon (1-8 wt%). Waste catalysts contain substances such as copper and zinc, and are therefore classified as hazardous waste. Furthermore, silicon powder is prone to oxidation and heat release when exposed to air, which may lead to spontaneous combustion. If not disposed of properly, it will not only waste resources such as silicon and copper, but also cause serious environmental pollution due to the corrosiveness of copper and the volatility of organic components.

[0003] Currently, waste electrode disposal mainly relies on hydrometallurgical recovery or pyrometallurgical processes. Hydrometallurgical processes use acid leaching to extract copper, but this is a lengthy process, costly, and generates highly polluting wastewater. While pyrometallurgical processes can enrich metal components, they are energy-intensive and prone to secondary pollution. Silicon, as a lithium-ion battery anode material, has a theoretical specific capacity as high as 4200 mAh / g, far exceeding that of traditional graphite (372 mAh / g). However, silicon experiences a volume expansion rate of up to 300% during charge and discharge, leading to electrode pulverization and failure, resulting in poor cycle performance. Nano-silicon-based anodes, leveraging the nanoscale effect, can effectively shorten the lithium-ion diffusion path and improve ion conductivity. Simultaneously, copper, as an excellent conductor, not only enhances the electronic conductivity of silicon but also effectively mitigates its volume expansion through a buffer structure. Nano-silicon-copper composite materials are anode materials that combine high capacity and stability.

[0004] Therefore, providing a method for preparing nano-silicon-based anode materials based on organosilicon waste contacts is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a nano-silicon-based anode material based on organosilicon waste contact material, its preparation method, and its application, addressing the shortcomings of existing technologies.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a nano-silicon-based anode material based on organosilicon waste electrodes, comprising the following steps: 1) Mix the waste organosilicon catalyst with a non-oxidizing acid solution and leach it to obtain copper silicon powder; 2) After mixing silicon copper powder with carbon source, the mixture is successively ground and subjected to thermal plasma treatment to obtain nanoscale silicon copper / carbon composite material; 3) Utilizing the catalytic effect of copper, carbon coating treatment is performed on the surface of nanoscale silicon-copper / carbon composite materials through chemical vapor deposition to obtain nanoscale silicon-based anode materials.

[0007] Preferably, the organosilicon waste catalyst in step 1) contains elemental silicon, copper, metallic impurities, and organosilicon residue. The metallic impurities include one or more of Fe, Al, and Zn. The non-oxidizing acid solution is one or more of hydrochloric acid, dilute sulfuric acid, phosphoric acid solution, and hydrofluoric acid. The concentration of the non-oxidizing acid solution is 0.01~5 mol / L. The liquid-to-solid ratio of the non-oxidizing acid solution to the organosilicon waste catalyst is ≥3 mL:1 g.

[0008] Preferably, the acid leaching temperature in step 1) is 0~80℃ and the acid leaching time is 0.1~10h; after acid leaching, the mixture is filtered, washed and dried in sequence to obtain silicon copper powder; the drying temperature is 50~120℃ and the drying time is 1~12h.

[0009] Preferably, the carbon source in step 2) comprises one or more of graphite, hard carbon, carbon black, mesophase carbon microspheres, chopped carbon fibers, carbon nanotubes, graphene, and porous activated carbon, and the mass of the carbon source is 0 to 60% of the mass of the silicon copper powder.

[0010] Preferably, the grinding method in step 2) is ball milling or sand milling, and the grinding time is ≥2h; the gas used for thermal plasma treatment is a protective gas, which includes one or more of argon, nitrogen and helium, with a gas flow rate of 5~100L / min and a gas velocity of 1~20m / s.

[0011] Preferably, the thermal plasma treatment in step 2) is either DC arc plasma treatment or radio frequency plasma treatment. The DC arc plasma treatment has a power of 5~100kW, an arc current of 50~300A, and an arc core temperature of 5000~15000K. The radio frequency plasma treatment has a power of 10~50kW, a radio frequency of 2~5MHz, and a feed rate of 10~100g / min.

[0012] Preferably, in step 3), a carbon coating process is performed by introducing a carbon deposition precursor source, which is a mixture of carbon source gas and carrier gas. The carbon source gas contains one or more of methane, acetylene, ethylene, propylene and carbon monoxide, and the carrier gas contains one or more of argon, nitrogen and helium. The volume ratio of carbon source gas to carrier gas is 1:1 to 20.

[0013] Preferably, the temperature of chemical vapor deposition in step 3) is 600~1200℃, the time is 0.5~10h, the gas flow rate is 1~200mL / min, and the rate of heating to the chemical vapor deposition temperature is 1~20℃ / min.

[0014] The present invention also provides a nano-silicon-based anode material based on organosilicon waste contact prepared by the aforementioned preparation method.

[0015] The present invention also provides the application of the aforementioned nano-silicon-based anode material based on organosilicon waste contacts in lithium-ion batteries.

[0016] The beneficial effects of this invention are: 1) Based on the compositional characteristics of waste organosilicon contacts, this invention first washes the waste organosilicon contacts with water and mixes them with a non-oxidizing acid solution for selective acid leaching to obtain silicon-copper powder. Then, the obtained silicon-copper powder is mixed with a carbon source, mechanically ground, and subjected to thermal plasma treatment to rapidly refine the particles and achieve carbon doping, resulting in a nanoscale silicon-copper / carbon composite material. Finally, utilizing the catalytic effect of copper, the nanoscale silicon-copper / carbon composite material is coated with carbon on its surface through chemical vapor deposition (CVD) to obtain a high-performance nanoscale silicon-based anode material. This achieves the resource recovery of waste organosilicon contacts, effectively alleviating the volume expansion problem of silicon-based materials during charging and discharging. At the same time, the high conductivity of copper significantly improves the electron transport efficiency of the electrode. The nanoscale silicon-based anode material prepared by this invention has excellent cycle stability and high capacity retention.

[0017] 2) The entire process of this invention does not require the introduction of an additional copper source, which not only solves the problem of waste catalyst disposal in the organosilicon industry and reduces the safety hazards and environmental pressure it brings, but also provides a new path for the low-cost, high-performance production of lithium-ion battery anode materials. The method of this invention has the characteristics of high processing efficiency, excellent product performance, and green and environmentally friendly process, providing a new idea for the value-added recycling of organosilicon waste catalysts and the sustainable development of new energy materials, and has certain economic and environmental benefits. Attached Figure Description

[0018] Figure 1 A schematic diagram of the process for preparing nano-silicon-based anode materials from organosilicon waste catalysts of the present invention; Figure 2This is a field emission electron microscope image of the silicon-copper / carbon composite material after radio frequency plasma treatment in Example 1; Figure 3 TEM image of the silicon-copper / carbon composite material after radio frequency plasma treatment in Example 1; Figure 4 This is a TEM image of the nano-silicon-based anode material from Example 1; Figure 5 This is a high-resolution TEM image of the silicon lattice fringes of the nano-silicon-based anode material in Example 1. Detailed Implementation

[0019] This invention provides a method for preparing a nano-silicon-based anode material based on organosilicon waste electrodes, comprising the following steps: 1) Mix the waste organosilicon catalyst with a non-oxidizing acid solution and leach it to obtain copper silicon powder; 2) After mixing silicon copper powder with carbon source, the mixture is successively ground and subjected to thermal plasma treatment to obtain nanoscale silicon copper / carbon composite material; 3) Utilizing the catalytic effect of copper, carbon coating treatment is performed on the surface of nanoscale silicon-copper / carbon composite materials by chemical vapor deposition (CVD) to obtain nanoscale silicon-based anode materials.

[0020] In this invention, the organosilicon waste contact material is preferably a water-washed organosilicon waste contact material.

[0021] In this invention, the organosilicon waste catalyst in step 1) preferably comprises elemental silicon, copper, metallic impurities, and organosilicon residue. The metallic impurities preferably comprise one or more of Fe, Al, and Zn. In the organosilicon waste catalyst, the mass fraction of elemental silicon is preferably 65-87%, more preferably 70-82%, and even more preferably 75-80%. The mass fraction of copper is preferably 5-19%, more preferably 8-13.5%, and even more preferably 9.2-12.8%. The copper exists in the organosilicon waste catalyst in the form of copper oxide and elemental copper. The mass fraction of metallic impurities is preferably 1-8%, more preferably 2.5-7.2%, and even more preferably 3-6%. The mass fraction of organosilicon residue is preferably 2-8%, more preferably 3-6.4%, and even more preferably 3.2-4.5%.

[0022] In this invention, the source of the organosilicon waste catalyst is: during the synthesis of organosilicon monomers, the silicon powder in the fluidized bed is discharged from the system as a powdery mixture due to the accumulation of carbon and impurities, which reduces the reaction performance.

[0023] In this invention, the non-oxidizing acid solution is preferably one or more of hydrochloric acid, dilute sulfuric acid, phosphoric acid solution, and hydrofluoric acid; the concentration of the non-oxidizing acid solution is preferably 0.01~5 mol / L, more preferably 0.1~4 mol / L, and even more preferably 1~3 mol / L; when there are two or more non-oxidizing acid solutions, the ratio of different types of acids is not limited and can be adjusted according to actual needs.

[0024] In this invention, the liquid-to-solid ratio of the non-oxidizing acid solution to the organosilicon waste catalyst is preferably ≥3mL:1g, more preferably ≥5mL:1g, and even more preferably ≥8mL:1g.

[0025] In this invention, the acid leaching temperature in step 1) is preferably 0~80℃, more preferably 20~60℃, and even more preferably 40~50℃, and the acid leaching time is preferably 0.1~10h, more preferably 0.5~6h, and even more preferably 1~5h; The purpose of acid leaching is to selectively remove metallic impurities (Fe, Al, Zn, etc.) from waste organosilicon catalysts while retaining valuable components such as silicon and copper, thereby purifying the waste organosilicon catalysts.

[0026] In this invention, after acid leaching, the product is preferably filtered, washed, and dried sequentially to obtain silicon-copper powder. The drying temperature is preferably 50~120℃, more preferably 60~100℃, and even more preferably 70~90℃. The drying time is preferably 1~12h, more preferably 2~10h, and even more preferably 4~8h. The parameters for filtration and washing are not limited, and the filtration and washing effects can be achieved by using process parameters well known in the art.

[0027] In this invention, the carbon source in step 2) preferably includes one or more of graphite, hard carbon, carbon black, mesophase carbon microspheres, chopped carbon fibers, carbon nanotubes, graphene, and porous activated carbon; when there are two or more carbon sources, the ratio of different types of carbon sources is not limited and can be adjusted as needed; the mass of the carbon source is preferably 0-60% of the mass of silicon copper powder, more preferably 10-55%, and more preferably 20-50%.

[0028] In this invention, the grinding method in step 2) is preferably ball milling or sand milling, and the grinding time is preferably ≥2h, more preferably ≥5h, and more preferably ≥10h; the gas used for thermal plasma treatment is a protective gas, which preferably includes one or more of argon, nitrogen and helium, and the gas flow rate is preferably 5~100L / min, more preferably 10~90L / min, and more preferably 30~80L / min, and the gas velocity is preferably 1~20m / s, more preferably 2~18m / s, and more preferably 10~15m / s.

[0029] In this invention, the thermal plasma treatment in step 2) is preferably DC arc plasma treatment or radio frequency plasma treatment. The power of the DC arc plasma treatment is preferably 5~100kW, more preferably 15~80kW, and more preferably 35~60kW. The arc current is preferably 50~300A, more preferably 80~250A, and more preferably 150~200A. The arc core temperature is preferably 5000~15000K, more preferably 8000~12000K, and more preferably 10000K. The power of the radio frequency plasma treatment is preferably 10~50kW, more preferably 12~40kW, and more preferably 15~30kW. The radio frequency is preferably 2~5MHz, more preferably 3~4MHz. The feed rate is preferably 10~100g / min, more preferably 15~90g / min, and more preferably 30~80g / min.

[0030] In this invention, the role of thermal plasma treatment is to: utilize its ultra-high temperature to instantly decompose the organic matter in the waste silicone catalyst, vaporize and remove volatile impurities, melt and uniformly mix the silicon with the copper impurities therein and rapidly cool and solidify it, and promote the rapid carbonization of the carbon source to form a carbon matrix that combines with silicon and copper to construct a nanoscale silicon-copper / carbon composite structure, thereby realizing the resource recovery and preliminary composite of waste catalyst.

[0031] In this invention, in the carbon coating process described in step 3), a carbon deposition precursor source is introduced. The carbon deposition precursor source is preferably a mixture of carbon source gas and carrier gas. The carbon source gas preferably includes one or more of methane, acetylene, ethylene, propylene, and carbon monoxide. The carrier gas preferably includes one or more of argon, nitrogen, and helium. The volume ratio of carbon source gas to carrier gas is preferably 1:1 to 20, more preferably 1:2 to 15, and even more preferably 1:3 to 10.

[0032] In this invention, the temperature of chemical vapor deposition in step 3) is preferably 600~1200℃, more preferably 700~1000℃, and even more preferably 800~900℃; the time is preferably 0.5~10h, more preferably 1~8h, and even more preferably 5~6h; the gas flow rate is preferably 1~200mL / min, more preferably 5~160mL / min, and even more preferably 10~120mL / min; and the rate of heating to the chemical vapor deposition temperature is preferably 1~20℃ / min, more preferably 3~15℃ / min, and even more preferably 5~10℃ / min.

[0033] In this invention, to ensure the uniformity of carbon coating, the reactor for carbon coating treatment by chemical vapor deposition is a horizontal tube furnace, a vertical tube furnace, or a fluidized bed reactor; the thickness of the carbon layer after carbon coating treatment is preferably 5~200nm, more preferably 10~150nm, and even more preferably 20~100nm.

[0034] The present invention also provides a nano-silicon-based anode material based on organosilicon waste contact prepared by the aforementioned preparation method.

[0035] The present invention also provides the application of the aforementioned nano-silicon-based anode material based on organosilicon waste contacts in lithium-ion batteries.

[0036] In this invention, the specific method of application is not limited, and any application method well known in the art can be used.

[0037] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0038] In this embodiment, the source of the organosilicon waste catalyst is: a powdery mixture in which silicon powder in the fluidized bed is discharged from the system by airflow due to carbon deposition and impurity accumulation during the synthesis of organosilicon monomers, resulting in a decrease in reaction performance; the reactor for carbon coating treatment by chemical vapor deposition is a fluidized bed reactor; the copper component in the organosilicon waste catalyst is in the form of both copper oxide and elemental copper, and the metallic impurities are Fe, Al and Zn.

[0039] Example 1

[0040] The waste silicone catalyst contained 84.5 wt% elemental silicon, 8 wt% copper, 3 wt% residual silicone, and 4.5 wt% metallic impurities. After washing the waste silicone catalyst with water at room temperature, it was selectively leached in hydrochloric acid (1 mol / L) at a liquid-to-solid ratio of 5 mL:1 g at 80 °C. The leaching was carried out with stirring for 1 hour. After leaching, the catalyst was filtered, washed, and dried at 80 °C for 5 hours to obtain copper-silicon powder. Silicon copper powder and hard carbon were mechanically ground for 5 hours at a rate of 800 rpm. The mass of hard carbon was 50% of the mass of silicon copper powder, resulting in a silicon copper / carbon mixed powder with an average particle size of 0.5 μm. The silicon copper / carbon mixed powder was then subjected to radio frequency plasma treatment in an argon atmosphere (gas flow rate of 80 L / min and gas velocity of 10 m / s) at a power of 30 kW, a radio frequency of 4 MHz, and a feed rate of 80 g / min, resulting in a silicon copper / carbon composite material with an average particle size of 0.2 μm. A carbon-coated precursor source with a gas flow rate of 80 mL / min was introduced. The carbon-coated precursor source was a mixture of 40% methane and 60% helium (by volume fraction). The temperature was increased to 900℃ at a rate of 5℃ / min using the catalytic effect of copper. After carbon coating treatment of the silicon-copper / carbon composite material by CVD at 900℃ for 2 hours, a high-performance nano-silicon-based anode material was obtained. The thickness of the carbon layer after coating was 20 nm.

[0041] Field emission electron microscopy (FEM) image of the silicon-copper / carbon composite material after radio frequency plasma treatment in Example 1 is shown below. Figure 2 As shown, the TEM image of the silicon-copper / carbon composite material after radio frequency plasma treatment in Example 1 is as follows. Figure 3 As shown; by Figure 2 and Figure 3 It can be seen that the silicon-copper / carbon composite material is a spherical material with copper particles attached to its surface.

[0042] TEM image of the nano-silicon-based anode material in Example 1 is shown below. Figure 4 As shown; by Figure 4 It can be seen that the nano-silicon-based anode material is a uniformly coated silicon-copper / carbon composite material.

[0043] High-resolution TEM image of the silicon lattice fringes of the nano-silicon-based anode material in Example 1 is shown below. Figure 5 As shown, silicon has a lattice spacing of d=0.31nm on the (111) crystal plane.

[0044] The tap density of the nano-silicon-based anode material obtained in Example 1 was tested to be 0.91 g / cm³. 3 .

[0045] The nano-silicon-based 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 / T 38823-2020. The test results showed that the initial discharge capacity of the nano-silicon-based anode material obtained in Example 1 could reach 2003.92 mAh / g.

[0046] Example 2

[0047] The waste silicone catalyst contained 82 wt% elemental silicon, 9.2 wt% copper, 4.8 wt% residual silicone, and 4 wt% metallic impurities. After washing the waste silicone catalyst with water at room temperature, it was selectively leached in hydrochloric acid (2 mol / L) at a liquid-to-solid ratio of 10 mL:1 g, and leached with stirring at 0 °C for 5 h. After leaching, it was filtered, washed, and dried at 60 °C for 10 h to obtain silicon-copper powder. Silicon-copper powder and chopped carbon fibers (150 μm in length) were mechanically ground for 10 hours at a rate of 800 rpm. The mass of the chopped carbon fibers was 50% of the mass of the silicon-copper powder, resulting in a silicon-copper / carbon mixed powder with an average particle size of 0.3 μm. The silicon-copper / carbon mixed powder was then subjected to radio frequency plasma treatment in an argon atmosphere (gas flow rate of 20 L / min and gas velocity of 18 m / s) at a power of 40 kW, a radio frequency of 2 MHz, and a feed rate of 100 g / min, resulting in a silicon-copper / carbon composite material with an average particle size of 0.15 μm. A carbon-coated precursor source with a gas flow rate of 1 mL / min was introduced. The carbon-coated precursor gas source was a mixture of 30% methane and 70% helium (by volume fraction). Using the catalytic effect of copper, the temperature was increased to 1100℃ at a heating rate of 8℃ / min. After surface carbon coating treatment of silicon-copper / carbon composite material at 1100℃ for 5 h by CVD, a high-performance nano-silicon-based anode material was obtained. The thickness of the carbon layer after coating was 30 nm.

[0048] The tap density of the nano-silicon-based anode material obtained in Example 2 was tested to be 0.89 g / cm³. 3 .

[0049] The nano-silicon-based anode material obtained in Example 2 was subjected to electrochemical performance testing. The testing method was carried out in Appendix D of the national standard GB / T 38823-2020. The test results showed that the initial discharge capacity of the nano-silicon-based anode material obtained in Example 2 could reach 1862.73 mAh / g.

[0050] Example 3

[0051] The waste silicone catalyst contained 78 wt% elemental silicon, 12.5 wt% copper, 5 wt% residual silicone, and 4.5 wt% metallic impurities. After washing the waste silicone catalyst with water at room temperature, it was selectively acid-leached in dilute sulfuric acid (1 mol / L concentration) at a liquid-to-solid ratio of 3 mL:1 g. The leaching was carried out at 40 °C with stirring for 2 h. After acid leaching, the catalyst was filtered, washed, and dried at 80 °C for 6 h to obtain copper-silicon powder. Silicon copper powder was mechanically ground with hard carbon and porous activated carbon for 20 hours at a grinding rate of 800 rpm. The mass of hard carbon and porous activated carbon was 25% of the mass of silicon copper powder, resulting in a silicon copper / carbon mixed powder with an average particle size of 0.35 μm. The silicon copper / carbon mixed powder was then subjected to radio frequency plasma treatment in an argon atmosphere (gas flow rate of 100 L / min and gas velocity of 12 m / s) at a power of 10 kW, a radio frequency of 3 MHz, and a feed rate of 15 g / min, resulting in a silicon copper / carbon composite material with an average particle size of 0.19 μm. A carbon-coated precursor source with a gas flow rate of 30 mL / min was introduced. The carbon-coated precursor gas source was a mixture of 20% acetylene and 80% helium (by volume fraction). Using the catalytic effect of copper, the temperature was increased to 600℃ at a heating rate of 10℃ / min. After surface carbon coating treatment of the silicon-copper / carbon composite material at 600℃ for 8 hours, a high-performance nano-silicon-based anode material was obtained. The thickness of the carbon layer after coating was 25 nm.

[0052] The tap density of the nano-silicon-based anode material obtained in Example 3 was tested to be 0.97 g / cm³. 3 .

[0053] The electrochemical performance of the nano-silicon-based anode material obtained in Example 3 was tested according to the method in Appendix D of the national standard GB / T 38823-2020. The test results showed that the initial discharge capacity of the nano-silicon-based anode material obtained in Example 3 could reach 1996.39 mAh / g.

[0054] Example 4

[0055] The waste silicone catalyst contained 79.4 wt% elemental silicon, 12 wt% copper, 3.6 wt% residual silicone, and 5 wt% metallic impurities. After washing the waste silicone catalyst at room temperature, it underwent selective acid leaching in a mixed acid solution of hydrochloric acid and dilute sulfuric acid (volume ratio of hydrochloric acid to dilute sulfuric acid was 1:1, both concentrations were 1 mol / L). The liquid-to-solid ratio of the mixed acid solution to the waste silicone catalyst was 8 mL:1 g. The leaching was carried out at 60°C with stirring for 5 hours. After acid leaching, the catalyst was filtered, washed, and dried at 80°C for 6 hours to obtain silicon-copper powder. Silicon-copper powder and mesophase carbon microspheres were mechanically ground for 10 hours at a rate of 800 rpm. The mass of the mesophase carbon microspheres was 50% of the mass of the silicon-copper powder, resulting in a silicon-copper / carbon mixed powder with an average particle size of 0.4 μm. The silicon-copper / carbon mixed powder was then subjected to radio frequency plasma treatment in an argon atmosphere (gas flow rate of 70 L / min and gas velocity of 12 m / s) at a power of 20 kW, a radio frequency of 5 MHz, and a feed rate of 30 g / min, resulting in a silicon-copper / carbon composite material with an average particle size of 0.23 μm. A carbon-coated precursor source with a gas flow rate of 50 mL / min was introduced. The carbon-coated precursor gas source was a mixture of 10% acetylene and 90% helium (by volume fraction). Using the catalytic effect of copper, the temperature was increased to 720℃ at a heating rate of 3℃ / min. After surface carbon coating treatment of the silicon-copper / carbon composite material at 720℃ for 1 h by CVD, a high-performance nano-silicon-based anode material was obtained. The thickness of the carbon layer after coating was 28 nm.

[0056] The tap density of the nano-silicon-based anode material obtained in Example 4 was tested to be 0.92 g / cm³. 3 .

[0057] The nano-silicon-based anode material obtained in Example 4 was subjected to electrochemical performance testing. The testing method was carried out in Appendix D of the national standard GB / T 38823-2020. The test results showed that the initial discharge capacity of the nano-silicon-based anode material obtained in Example 4 could reach 2153.04 mAh / g.

[0058] Example 5

[0059] The waste silicone catalyst contained 80 wt% elemental silicon, 10.5 wt% copper, 4.5 wt% residual silicone, and 5 wt% metallic impurities. After washing the waste silicone catalyst at room temperature, it underwent selective acid leaching in a mixed acid solution of hydrochloric acid and dilute sulfuric acid (volume ratio of hydrochloric acid to dilute sulfuric acid: 1:1, both concentration 2 mol / L). The liquid-to-solid ratio of the mixed acid solution to the waste silicone catalyst was 20 mL: 1 g. The leaching was carried out at 20 °C with stirring for 3 hours. After acid leaching, the catalyst was filtered, washed, and dried at 80 °C for 6 hours to obtain silicon-copper powder. Silicon-copper powder was mechanically ground for 5 hours at a rate of 800 rpm to obtain a silicon-copper mixed powder with an average particle size of 0.48 μm. The silicon-copper mixed powder was then subjected to radio frequency plasma treatment in an argon atmosphere (gas flow rate of 100 L / min and gas flow velocity of 15 m / s) at a power of 50 kW, a radio frequency of 4 MHz, and a feed rate of 60 g / min to obtain a silicon-copper composite material with an average particle size of 0.21 μm. A carbon-coated precursor source with a gas flow rate of 10 mL / min was introduced. The carbon-coated precursor gas source was a mixture of 10% methane, 5% acetylene and 85% helium (by volume fraction). Using the catalytic effect of copper, the temperature was increased to 800℃ at a heating rate of 12℃ / min. After carbon coating treatment of the silicon-copper composite material at 800℃ for 3 hours, a high-performance nano-silicon-based anode material was obtained. The thickness of the carbon layer after coating was 18 nm.

[0060] The tap density of the nano-silicon-based anode material obtained in Example 5 was tested to be 0.81 g / cm³. 3 .

[0061] The electrochemical performance of the nano-silicon-based anode material obtained in Example 5 was tested according to the method in Appendix D of the national standard GB / T 38823-2020. The test results showed that the initial discharge capacity of the nano-silicon-based anode material obtained in Example 5 could reach 1832.68 mAh / g.

[0062] This invention utilizes a thermal plasma method for the efficient and resource-based recycling of waste organosilicon contacts. The copper component within these contacts is then used to synthesize high-performance nano-silicon-based anode materials. This approach not only solves the environmental pollution problem associated with waste organosilicon contacts but also achieves the high-value synergistic utilization of silicon and copper resources. The nano-silicon-based anode material prepared by this invention exhibits high tap density, high specific capacity, and excellent cycle stability, providing a new approach for the low-cost and green preparation of lithium-ion battery anode materials.

[0063] 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 a nano-silicon-based anode material based on organosilicon waste catalyst, characterized in that, It includes the following steps: 1) Mix the waste organosilicon catalyst with a non-oxidizing acid solution and leach it to obtain copper silicon powder; 2) After mixing silicon copper powder with carbon source, the mixture is successively ground and subjected to thermal plasma treatment to obtain nanoscale silicon copper / carbon composite material; 3) Utilizing the catalytic effect of copper, carbon coating treatment is performed on the surface of nanoscale silicon-copper / carbon composite materials through chemical vapor deposition to obtain nanoscale silicon-based anode materials.

2. The preparation method according to claim 1, characterized in that, Step 1) The organosilicon waste catalyst contains elemental silicon, copper, metallic impurities, and organosilicon residue. The metallic impurities include one or more of Fe, Al, and Zn. The non-oxidizing acid solution is one or more of hydrochloric acid, dilute sulfuric acid, phosphoric acid solution, and hydrofluoric acid. The concentration of the non-oxidizing acid solution is 0.01~5 mol / L. The liquid-to-solid ratio of the non-oxidizing acid solution to the organosilicon waste catalyst is ≥3 mL:1 g.

3. The preparation method according to claim 1 or 2, characterized in that, Step 1) The acid leaching temperature is 0~80℃ and the acid leaching time is 0.1~10h; after acid leaching, the mixture is filtered, washed and dried in sequence to obtain silicon copper powder; the drying temperature is 50~120℃ and the drying time is 1~12h.

4. The preparation method according to claim 3, characterized in that, Step 2) The carbon source includes one or more of graphite, hard carbon, carbon black, mesophase carbon microspheres, chopped carbon fibers, carbon nanotubes, graphene and porous activated carbon, and the mass of the carbon source is 0 to 60% of the mass of the silicon copper powder.

5. The preparation method according to claim 4, characterized in that, Step 2) The grinding method is ball milling or sand milling, and the grinding time is ≥2h; the gas for thermal plasma treatment is a protective gas, which includes one or more of argon, nitrogen and helium, with a gas flow rate of 5~100L / min and a gas velocity of 1~20m / s.

6. The preparation method according to claim 4 or 5, characterized in that, Step 2) The thermal plasma treatment is either DC arc plasma treatment or radio frequency plasma treatment. The DC arc plasma treatment has a power of 5~100kW, an arc current of 50~300A, and an arc core temperature of 5000~15000K. The radio frequency plasma treatment has a power of 10~50kW, a radio frequency of 2~5MHz, and a feed rate of 10~100g / min.

7. The preparation method according to claim 6, characterized in that, In step 3), a carbon coating process is performed by introducing a carbon deposition precursor source, which is a mixture of carbon source gas and carrier gas. The carbon source gas contains one or more of methane, acetylene, ethylene, propylene and carbon monoxide, and the carrier gas contains one or more of argon, nitrogen and helium. The volume ratio of carbon source gas to carrier gas is 1:1 to 20.

8. The preparation method according to claim 7, characterized in that, Step 3) The temperature of the chemical vapor deposition is 600~1200℃, the time is 0.5~10h, the gas flow rate is 1~200mL / min, and the rate of heating to the chemical vapor deposition temperature is 1~20℃ / min.

9. The nano-silicon-based anode material based on organosilicon waste electrode prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the nano-silicon-based anode material based on organosilicon waste electrode as described in claim 9 in lithium-ion batteries.

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