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CN-122025894-A - Method for preparing silicon-based negative electrode material by recycling silicon-oxygen negative electrode waste

CN122025894ACN 122025894 ACN122025894 ACN 122025894ACN-122025894-A

Abstract

The invention discloses a method for preparing a silicon-based negative electrode material by recycling silicon-oxygen negative electrode waste, which comprises the following steps of (1) pretreating E-class waste, mixing the E-class waste with A-class waste, B-class waste, C-class waste and D-class waste to obtain a mixture, (2) crushing the mixture until the particle size D50 is 5-7 mu m, D10 is more than or equal to 1 mu m and D90 is less than 19 mu m to obtain a powder mixture, (3) refining the powder mixture, uniformly mixing the powder mixture with magnesium powder, carrying out vacuum gasification separation to obtain a gaseous silicon-oxygen compound and gaseous magnesium, and obtaining a solid residue as carbon powder, mixing the gaseous silicon-oxygen compound and the gaseous magnesium, leading out a condenser for cooling deposition, crushing, scattering and coating by CVD carbon to obtain a pre-magnesium silicon-oxygen material, (4) respectively weighing the pre-magnesium silicon-oxygen material and a graphite material, carrying out demagnetizing and sieving to obtain a silicon-carbon material after uniform mixing.

Inventors

  • LI JUNLI
  • WANG ZHIWEN
  • JIANG NINGLIN
  • HAN PEIJIE
  • WANG SHUAI

Assignees

  • 内蒙古杉杉科技有限公司

Dates

Publication Date
20260512
Application Date
20260310

Claims (9)

  1. 1. The method for preparing the silicon-based negative electrode material by recycling the silicon-oxygen negative electrode waste is characterized by comprising the following steps of: (1) Pretreating E-class waste, and mixing with A-class waste, B-class waste, C-class waste and D-class waste to obtain a mixture; (2) Crushing the mixture to a particle size D50 of 5-7 mu m, wherein D10 is more than or equal to 1 mu m, and D90 is less than 19 mu m to obtain a powder mixture; (3) The powder mixture is subjected to refining treatment and is uniformly mixed with magnesium powder, and is subjected to vacuum gasification separation to obtain a gaseous silicon-oxygen compound and gaseous magnesium, wherein the solid residue is carbon powder; the gaseous silicon-oxygen compound and the gaseous magnesium are mixed and led out to a condenser for cooling and deposition, and the mixture is broken up, scattered and coated by CVD carbon to obtain a pre-magnesium silicon-oxygen material; (4) And respectively weighing the pre-magnesium silica material and the graphite material, uniformly mixing, and then carrying out demagnetizing and screening to obtain the silicon-carbon material.
  2. 2. The method for preparing the silicon-based negative electrode material by recycling silicon-oxygen negative electrode waste according to claim 1, wherein in the step (2), the mass ratio of carbon element in the powder mixture is 40% -50%, the mass ratio of silicon element is 20% -40%, the mass ratio of oxygen element is 15% -25%, and the ratio of trace impurities is less than or equal to 5%.
  3. 3. The method for preparing a silicon-based negative electrode material by recycling silicon-oxygen negative electrode waste material according to claim 1, wherein in the step (3), the specific operation of vacuum gasification separation comprises: (3.1) uniformly mixing the powder mixture and the magnesium powder, and then placing the mixture in a vacuum furnace; (3.2), gradually and gradually vacuumizing: the mechanical pump and the pre-pumping valve are opened, the opening degree of the proportional ball valve is adjusted to be 20%, and the pressure is reduced to 40Kpa at the speed of 1-5 kPa/h; Opening a backing valve, and reducing the pressure to 1200Pa at a rate of 5-10 kPa/h; starting the Roots pump, and reducing the pressure to 50pa at a speed of 15-20 kPa/h; the opening of the proportional ball valve is adjusted to be 50 percent, and the pressure is reduced to 20pa at the speed of 22-25 kPa/h; The opening of the proportional ball valve is adjusted to be 100%, the pressure is reduced to be less than 1Pa at the speed of 27-30kPa/h, and when the pressure in the vacuum furnace is less than 10Pa, the power supply of the diffusion pump is started to preheat the vacuum furnace for 20min-1h; (3.3) high-temperature separation, namely, the pressure in the vacuum furnace is reduced to below 1Pa, the temperature is raised to 900-1500 ℃, the constant temperature and the constant pressure are kept for 30-1200 min, and finally, the gaseous silicon oxide, the gaseous magnesium and the solid residue carbon powder are obtained.
  4. 4. The method for preparing a silicon-based negative electrode material by recycling silicon-oxygen negative electrode waste according to claim 1, wherein in the step (3), the mass ratio of the powder mixture to the magnesium powder is (8-9.5) (0.5-2).
  5. 5. The method for preparing the silicon-based negative electrode material by recycling the silicon-oxygen negative electrode waste material according to claim 1, wherein in the step (3), the specific method for refining treatment comprises the steps of classifying and screening the powder mixture, selecting fine particles with the particle size of 5-7 mu m, then placing the powder mixture in an inert gas protection atmosphere, and carrying out surface passivation treatment by adopting low-temperature plasma with the plasma power of 80-150W and the treatment time of 5-15min.
  6. 6. The method for producing a silicon-based negative electrode material according to claim 5, wherein in the step (3), the cooling temperature of the cooling deposition is 300 ℃ to 500 ℃.
  7. 7. The method for producing a silicon-based negative electrode material by recycling silicon-oxygen negative electrode waste material according to claim 1, wherein in said step (4), the mass ratio of said pre-magnesium silicon-oxygen material to said graphite material is (1-2): (8-9).
  8. 8. The method for preparing the silicon-based negative electrode material by recycling the silicon-oxygen negative electrode waste material according to claim 7, wherein in the step (4), the preparation method of the graphite material comprises the steps of mixing and granulating carbon powder, petroleum coke and asphalt according to a mass ratio of (7-10) to (2-5) to 1, and graphitizing at 2800-3000 ℃ to obtain the graphite material.
  9. 9. The method for preparing a silicon-based negative electrode material by recycling silicon-oxygen negative electrode waste according to claim 8, wherein the particle size distribution of the graphite material is 4-38 μm and the particle size D50 is 12-16 μm.

Description

Method for preparing silicon-based negative electrode material by recycling silicon-oxygen negative electrode waste Technical Field The invention belongs to the technical field of silicon-based negative electrode materials, and particularly relates to a method for preparing a silicon-based negative electrode material by recycling silicon-oxygen negative electrode waste. Background Along with the gradual industrialization and scale-up of new energy automobiles, the yield of lithium batteries is increased, and the theoretical specific capacity of a silicon oxygen material (such as a silicon oxygen compound, x=1) can reach 2400mAh/g, which is far higher than that of a traditional graphite cathode (372 mAh/g). Although the capacity of pure silicon (Si) is higher (4200 mAh/g), the silicon oxygen material alleviates the problem of silicon volume expansion by introducing oxygen atoms. It is remarkable that silicon-oxygen negative electrodes represent an early commercialization as silicon-based materials, and commercial silicon-oxygen negative electrodes (e.g., silicon-oxygen compound/C composites) typically have capacities of 1500-1800mAh/g, yet are significantly better than graphite. The cost of the current pure silicon oxide is 5-10 ten thousand/ton. The prior art of the first generation of silicon and oxygen in the market is that the bulk silicon and oxygen compound is crushed and then is coated by CVD gas phase carbon, and the carbon content is not more than 6 percent. Industrial production is typically carried out using a CVD rotary kiln, where waste materials are generated during the gas phase cladding process, wherein the waste materials include: The A-type waste is discharged after cracking and utilizing carbon source gas (hydrocarbon gas, aromatic hydrocarbon and the like), and the discharged process gas flow takes away small-particle-size carbon-coated silica compound materials, wherein the part of the collected materials are unqualified materials; Class B waste, namely, silicon oxide microparticles are aggregated in a reactor under the coating atmosphere and the holding of cracking carbon due to static electricity or Van der Waals force to form large particles, and unqualified waste is generated; the C-type waste is characterized in that carbon source gases (hydrocarbon gases, aromatic hydrocarbons and the like) are locally pyrolyzed at high temperature to generate solid carbon particles (non-target coated carbon) to form a mixture of amorphous carbon blocks and silicon-oxygen compounds, and materials with different contents are mixed in the materials, wherein the generation of the materials is waste; D class waste materials, namely, bonding silica compounds on the furnace wall after carbon coating to form sheet materials, wherein the sheet materials fall off in the rotating process of the furnace body, sieving treatment is carried out in the running process of equipment, and the carbon content of the oversize materials is uneven and cannot be used normally and are regarded as waste materials; E class waste materials, namely carbon-coated silica compounds can be used as lithium battery negative electrode materials for battery assembly test, and the electrode materials are mixed, coated, rolled, compacted in density, compacted in two times and the like in the previous working procedures of the battery, and the like, so that the waste materials of the unqualified silica-based negative electrode plates are produced due to various reasons. The components of the waste materials are SiO materials and carbon mixtures, the waste materials, leftover materials and the like are scrapped at will, so that material waste is caused, the industrial cost is high, the electrolyte remained by a pole piece can harm the environment, most importantly, the body structure of the negative pole waste materials and leftover materials is not seriously damaged, the negative pole waste materials and the leftover materials are easy to recycle, if the negative pole waste materials and the leftover materials are recycled, waste materials produced by the industrialization of silicon-based materials can be changed into valuable materials, the waste materials produced by the industrialization of the silicon-based materials can be changed into new products, the cost of material manufacturers can be reduced, and the research on recycling of silicon and carbon powder in the silicon-based negative pole materials is insufficient in the current industry. Disclosure of Invention The invention aims to provide a method for preparing a silicon-based negative electrode material by recycling silicon-oxygen negative electrode waste. The method for preparing the silicon-based negative electrode material by recycling the silicon-oxygen negative electrode waste material comprises the following steps: (1) Pretreating E-class waste, and mixing with A-class waste, B-class waste, C-class waste and D-class waste to obtain a mixture; (2) Crushing the mixture t