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CN-116960304-B - Sandwich hollow core-shell type silicon carbon material and preparation method thereof

CN116960304BCN 116960304 BCN116960304 BCN 116960304BCN-116960304-B

Abstract

The invention relates to an interlayer hollow core-shell type silicon-carbon material and a preparation method thereof, wherein the interlayer hollow core-shell type silicon-carbon material takes nano silicon powder as a core, carbon black as a shell, and the carbon black comprises, by mass, 40-98 parts of carbon black and 2-60 parts of nano silicon powder. The sandwich hollow core-shell type silicon-carbon material can be prepared in a large-scale, efficient and low-cost manner by the method.

Inventors

  • HUANG XIFU
  • BU QINGPENG
  • ZHU SHEJIAO
  • Ji Yibiao
  • DU JIHUI

Assignees

  • 宁波德泰化学有限公司

Dates

Publication Date
20260508
Application Date
20230811

Claims (6)

  1. 1. A preparation method of an interlayer hollow core-shell type silicon carbon material is characterized in that, The sandwich hollow core-shell type silicon carbon material takes nano-grade silicon powder as a core, takes carbon black as a shell, and takes 40-98 parts of carbon black, 2-60 parts of nano-grade silicon powder and amorphous carbon as the carbon black in parts by weight; The preparation process is carried out in a reaction furnace, the reaction furnace comprises a combustion chamber, a throat section, a reaction section and a quenching section which are sequentially arranged, and the preparation method comprises the following steps: S1, introducing combustion oil into a combustion chamber, and after the temperature of the combustion chamber is adjusted to 1500-1700 ℃, introducing silicon powder solvent dispersion liquid into the front part of the combustion chamber from the side, wherein the temperature is reduced to 1300-1400 ℃; s2, introducing the cavity auxiliary agent aqueous solution into the front part of the combustion chamber from the side, and reducing the temperature to 1000-1100 ℃; S3, introducing the uniformly mixed raw oil into the rear part of the combustion chamber, and reducing the temperature to 800-900 ℃; S4, heating the reaction section to 1400-1500 ℃, and reducing the temperature to 1100-1200 ℃ after the raw oil passes through; s5, adding the aqueous solution of the particle size control agent into a reaction furnace; S6, adding quench water into a quenching section, reducing the temperature to below 240 ℃, and separating to obtain a core-shell type silicon-carbon material containing a cavity auxiliary agent and a particle size control agent; S7, dispersing the core-shell type silicon-carbon material containing the cavity auxiliary agent and the particle size control agent in hot water at 50-60 ℃, stirring, filtering by adopting a plate frame, performing at least one operation, dispersing in water after the content of magnesium and potassium is lower than 40ppm, performing spray drying at 160-180 ℃, drying until the heating decrement is lower than 1wt.%, and demagnetizing to obtain the sandwich hollow core-shell type silicon-carbon material; The preparation method of the silicon powder solvent-type dispersion liquid comprises the following steps: firstly adding an oily dispersing agent and grinding resin into a solvent which is stirred at a high speed, after stirring uniformly, slowly adding nanoscale silicon powder, stirring for 30-60min to obtain a pre-dispersion liquid of the silicon powder, and grinding the fineness of the pre-dispersion liquid of the silicon powder to 0.3-3 mu m to obtain the silicon powder solvent-type dispersion liquid.
  2. 2. The method for preparing the sandwich hollow core-shell type silicon-carbon material according to claim 1, wherein, The nano silicon powder is obtained by a mechanical grinding method, and the particle size of the nano silicon powder is 0.1-0.9 mu m; And/or the silicon powder solvent-based dispersion liquid contains 20-30wt.% of nanoscale silicon powder; and/or the silicon powder solvent dispersion liquid contains 2-6wt% of oily dispersing agent; And/or the content of grinding resin in the silicon powder solvent dispersion is 40-50wt%; and/or the silicon powder solvent-based dispersion contains 14-38 wt.% of solvent.
  3. 3. The method for preparing the sandwich hollow core-shell type silicon-carbon material according to claim 1, wherein, The oily dispersing agent is at least one of modified polyester polymer solution, modified polyurethane polymer, polyester modified polyphosphate compound, unsaturated polyamide carboxylate and high molecular weight unsaturated carboxylic acid; And/or the solvent is at least one of solvent oil, rosin water, toluene and xylene; And/or the grinding resin is solvent type grinding resin, and comprises at least one of acrylic resin, phenolic resin and alkyd resin.
  4. 4. The method for preparing the sandwich hollow core-shell type silicon-carbon material according to claim 1, wherein, The burning oil is ethylene tar; And/or the raw oil is at least one of clear oil, anthracene oil, ethylene tar and coal tar, and the dosage is 1.6-1.7 times of the mass of the carbon black, wherein the mass of the carbon black is obtained according to accumulated data of a production line.
  5. 5. The method for preparing the sandwich hollow core-shell type silicon-carbon material according to claim 1, wherein, The grain size control agent is at least one of potassium carbonate, potassium oxide and potassium hydroxide, the feeding position of the grain size control agent aqueous solution is any place of the reaction section and the quenching section, the dosage of the grain size control agent is 1-3 wt.% of the demagnetized interlayer hollow core-shell type silicon carbon material, and the solid content of the grain size control agent aqueous solution is 10-20 wt.%.
  6. 6. The method for preparing the sandwich hollow core-shell type silicon-carbon material according to claim 1, wherein, The cavity auxiliary agent is magnesium sulfate, the dosage of the cavity auxiliary agent is 20-30wt% of the mass of the silicon powder, and the cavity auxiliary agent aqueous solution contains 10-20wt% of magnesium sulfate.

Description

Sandwich hollow core-shell type silicon carbon material and preparation method thereof Technical Field The invention relates to the field of silicon carbon materials, in particular to an interlayer hollow core-shell type silicon carbon material and a preparation method thereof. Background The silicon material applied to the negative electrode of the lithium battery and lithium form silicon-lithium alloy, the theoretical specific capacity is up to 3572mA.h/g, which is far higher than the theoretical specific capacity of commercial graphite, namely 372mA.h/g, but the silicon volume expansion rate is up to 270% in the process of forming the alloy by the silicon material and lithium, so that the silicon material is easy to pulverize, the electrode structure is unstable and fails, the collapse of the electrode structure and the peeling of the active material are caused, and the capacity of the electrode is greatly reduced and even completely fails. The carbonaceous anode material is the anode material commonly used for batteries, such as graphite, mesophase microspheres and the like, has relatively small volume change in the charge and discharge process, has good circulation stability and good conductivity, and can improve the volume effect of silicon and greatly improve the electrochemical stability by closely combining silicon and carbon. Chinese patent CN 105304874B discloses a method for preparing a sandwich hollow double-layer carbon/silicon composite lithium ion battery negative electrode material. The invention adopts an etching method, takes phenolic resin and dopamine as carbon sources, takes ethanol/water mixed solution as a solvent, takes silicon dioxide as a hard template, and prepares the double-layer carbon/silicon composite nano material with a sandwich hollow structure through accurate calculation and regulation and control of synthesis parameters. Uniformly dispersing nano silicon powder in deionized water according to the mass volume ratio of 1:2 mg/mL, adding a mixed solution of ethanol and 25-28 wt.% of ammonia water, wherein the volume ratio of ethanol to ammonia water is 20:1, stirring for reaction of 5min, adding tetraethyl orthosilicate (TEOS), stirring for 6 h at 30 ℃, centrifuging, washing, Drying to obtain Si@SiO2, b, adding 25-28 wt.% ammonia water into a mixed solution prepared by ethanol and deionized water according to a volume ratio of 2:1, mixing uniformly, stirring at 30 ℃ for 0.5 h, adding Si@SiO2 powder obtained in the step a to make the mass volume ratio of Si@SiO2 powder to the mixed solution be 10.5 mg/mL, adding resorcinol and 37 wt% formaldehyde solution, stirring for 24-h, loading the mixed solution into a 50mL autoclave with polytetrafluoroethylene lining, reacting at 100 ℃ for 18-24 h, centrifuging the product, separating, Uniformly dispersing Si@SiO2@RF powder in deionized water according to the mass volume ratio of 7:4 mg/mL, adding a mixed solution of ethanol and 25-28 wt.% ammonia water, wherein the volume ratio of ethanol to ammonia water is 20:1, stirring and reacting for 5min ℃, adding tetraethyl orthosilicate (TEOS), stirring for 6 h at 30 ℃, centrifuging, washing, and removing impurities, Drying to obtain Si@SiO2@RF@SiO2, d. Completely dissolving Si@SiO2@RF@SiO2 powder obtained in the step C and dopamine hydrochloride (PDA) powder in a mass ratio of 3:1 into borax buffer solution with pH=9.18, stirring at normal temperature to react for 24h, washing and drying to obtain Si@SiO2@RF@SiO2@PDA, calcining the powder at 600-900 ℃ for 2-3 h under inert atmosphere to obtain Si@SiO2@C@SiO2@C, e. Adding 0.5-3 wt.% of HF solution into the Si@SiO2@C@SiO2@C obtained in the step d to etch for 1-30 min, centrifuging the product after the etching is completed, Washing and drying to obtain the sandwich hollow double-layer carbon/silicon composite nano material. the process has the advantages of complex conditions, low efficiency, use of HF acid in the process, poor environmental protection and inapplicability to large-scale production. Chinese patent CN110828814B discloses a silicon &#x2011, carbon &#x2011, graphene electrode material, preparation method and application of the material. The material has a structure that silicon &#x2011 with a sandwich hollow double-shell structure is formed, carbon particles are fixed on a redox graphene sheet layer, the silicon &#x2011 is formed by wrapping a SiOx layer on the surface of a nano silicon particle inner core of the carbon particles, the outermost layer is a carbon layer, and a hollow layer is arranged between the SiOx layer and the carbon layer. The thickness of SiOx layer is 0.1-1nm, the thickness of carbon layer is 0.2-2nm, and the thickness of hollow layer is 2-10nm, and the preparation method of the material comprises forming SiOx layer on nano silicon surface, dispersing in polydiallyl dimethyl ammonium chloride solution, adsorbing, and separating solid particles; and adding solid particles into the graphene o