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CN-122025571-A - Boron doped porous silicon carbon composite material and preparation method thereof

CN122025571ACN 122025571 ACN122025571 ACN 122025571ACN-122025571-A

Abstract

The invention discloses a boron doped porous silicon carbon composite material and a preparation method thereof, wherein the preparation method comprises the following steps of S1, carrying out high-energy ball milling on silicon dioxide, a solid carbon source and boron-containing particles to obtain a mixed product A, S2, carrying out mechanical mixing on the mixed product A and magnesium powder to obtain a mixed product B, S3, placing the mixed product B in a reactor, roasting at 600-1000 ℃ for 6-9 h under an inert condition, naturally cooling to obtain a mixed product C, S4, carrying out acid washing on the mixed product C in dilute acid and hydrofluoric acid, washing with pure water and absolute ethyl alcohol, and centrifugally drying to obtain the boron doped porous silicon carbon composite material. The method has the advantages of simple process and low raw material cost, and the prepared boron doped porous silicon-carbon composite material has high conductivity and good cycle stability.

Inventors

  • WANG CHEN
  • DING XIAOYANG
  • WU YUHU
  • LI YUFEI

Assignees

  • 宁波杉杉硅基材料有限公司

Dates

Publication Date
20260512
Application Date
20251229

Claims (10)

  1. 1. The preparation method of the boron doped porous silicon carbon composite material is characterized by comprising the following steps of: s1, performing high-energy ball milling on silicon dioxide, a solid carbon source and boron-containing particles to obtain a mixed product A; s2, mechanically mixing the mixed product A with magnesium powder to obtain a mixed product B; s3, placing the mixed product B in a reactor, roasting at 600-1000 ℃ for 6-9 hours under an inert condition, and naturally cooling to obtain a mixed product C; and S4, sequentially carrying out acid washing on the mixture C in dilute acid and hydrofluoric acid, washing the mixture C by pure water and absolute ethyl alcohol, and centrifugally drying the mixture C to obtain the boron doped porous silicon-carbon composite material.
  2. 2. The preparation method of claim 1, wherein in the step S1, the molar ratio of the silicon dioxide, the boron-containing particles and the solid carbon source is 1 (0.1-0.5): (0.5-4), the boron-containing particles are at least one of boric acid, sodium borate and borax, and the solid carbon source is at least one of calcium carbonate, sodium carbonate, potassium carbonate and magnesium carbonate.
  3. 3. The preparation method according to claim 1, wherein the high-energy ball milling in the step S1 is performed at a rotational speed of 300-1000 rpm for 1-20 hours.
  4. 4. The preparation method of claim 1, wherein the molar ratio of the mixed product A to the magnesium powder in the step S2 is 1 (0.25-2).
  5. 5. The method of claim 1, wherein the mechanical mixing in step S2 is milling, ball milling or stirring.
  6. 6. The method according to claim 5, wherein the mechanical mixing in step S2 is performed at a rotational speed of 50 to 300rpm for 0.5 to 1 hour.
  7. 7. The preparation method of claim 1, wherein in the step S4, the dilute acid is at least one of dilute hydrochloric acid, dilute nitric acid and dilute sulfuric acid, the concentration of the dilute acid is 1-3 mol/L, and the concentration of the hydrofluoric acid is 1-3 mol/L.
  8. 8. The method according to claim 1, wherein the washing in step S4 is performed by washing with pure water followed by washing with absolute ethanol.
  9. 9. The preparation method according to claim 1, wherein in the step S4, centrifugal drying is carried out at a rotation speed of 700-900 rpm for 1-3 min, and then the mixture is placed in a vacuum drying oven for drying at a temperature of 60-80 ℃ under a pressure of-0.08 to-0.1 Mpa for 8-12h.
  10. 10. A boron doped porous silicon carbon composite material prepared by the method of any one of claims 1 to 9.

Description

Boron doped porous silicon carbon composite material and preparation method thereof Technical Field The invention relates to the technical field of lithium ion battery materials, in particular to a boron doped porous silicon-carbon composite material and a preparation method thereof. Background Silicon has the theoretical specific capacity of 4200 mAh g -1 (more than 10 times of graphite) as a new generation lithium ion battery cathode material, and is widely studied with the advantages of a suitable lithium intercalation platform, abundant natural resources and the like, but the low conductivity of silicon and the huge volume expansion (about 300%) in the lithium deintercalation process limit the commercialization development of silicon-based materials. Poor conductivity makes the high-current charge and discharge performance of the battery less than ideal, and volume expansion may cause damage to the electrode structure, rapid capacity decay, and instability of Solid Electrolyte Interface (SEI), thereby reducing the coulombic efficiency and cycle life of the battery. In order to solve the problems, the silicon material is subjected to porosification, doping and carbon coating surface modification, so that the volume expansion of the silicon in the lithium intercalation process can be effectively relieved by the porosification, and the structural stability of the electrode is improved. The doping and carbon coating surface modification can limit the volume expansion of silicon, prevent the silicon from being in direct contact with electrolyte, reduce the occurrence of side reaction, improve the transmission rate of lithium ions and electrons and improve the conductivity of the material. The existing porous silicon-based material has the problems of high raw material cost, complex technical route, requirement on multi-step procedures for material preparation, high requirement on equipment conditions and the like. For example, the negative electrode material of the boron doped composite silicon-based lithium ion battery and the preparation method thereof disclosed in the patent CN117080407A have good cycle performance, but the silicon raw material is nano silicon, vacuum high-temperature equipment is needed, the material cost is high, and the material is not suitable for commercial production. The preparation method of the lithium secondary battery lithium boron silicon alloy anode active material disclosed in the patent CN111009647B is complex, the preparation method of the anode active material disclosed in the patent CN110838584A is complex, the problem of complex preparation method of the anode active material is also existed, and the problem of sintering of the material cannot be fundamentally solved due to NaCl added in the process of magnesium thermal reduction reaction. Disclosure of Invention The invention aims to solve the technical problems that the existing porous silicon-based material has high raw material cost and complex preparation technical route, and the invention provides the boron doped porous silicon-carbon composite material and the preparation method thereof in order to overcome the defects of the prior art. The first aspect of the invention provides a preparation method of a boron doped porous silicon carbon composite material, which comprises the following steps: s1, performing high-energy ball milling on silicon dioxide, a solid carbon source and boron-containing particles to obtain a mixed product A; s2, mechanically mixing the mixed product A with magnesium powder to obtain a mixed product B; s3, placing the mixed product B in a reactor, roasting at 600-1000 ℃ for 6-9 hours under an inert condition, and naturally cooling to obtain a mixed product C; and S4, sequentially carrying out acid washing on the mixture C in dilute acid and hydrofluoric acid, washing the mixture C by pure water and absolute ethyl alcohol, and centrifugally drying the mixture C to obtain the boron doped porous silicon-carbon composite material. In the scheme, silicon dioxide is used as a silicon source, magnesium powder is used as a reducing agent, boron particles are used as a doping agent, calcium carbonate is used as a carbon source, the boron doped porous silicon-carbon composite material is obtained through acid washing and etching after high-energy ball milling and one-step reaction, and the silicon dioxide and the calcium carbonate are all substances widely existing in the nature, so that the extraction cost is low, the reserve is high, and no pollution is caused. Magnesium powder and silicon dioxide can generate magnesium silicide and silicon at high temperature, calcium carbonate can be decomposed into carbon dioxide and calcium oxide at high temperature, and carbon dioxide can oxidize magnesium powder and magnesium silicide to generate calcium oxide, carbon, porous silicon and magnesium oxide. Therefore, the porous silicon-carbon composite material can be prepared by a high-temperature one-step ma