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CN-122000330-A - Spherical artificial graphite composite particles and spray drying preparation method and application thereof

CN122000330ACN 122000330 ACN122000330 ACN 122000330ACN-122000330-A

Abstract

The application relates to the technical field of battery cathode materials, and discloses spherical artificial graphite composite particles, a spray drying preparation method and application thereof, the composite particles are prepared from artificial graphite, silicon-based active materials, a conductive agent and a liquid-phase binder system, and have a spherical structure with compact shell and communicated pores inside. The micron pore diameter distribution inside the particles is 0.5-3 mu m and accounts for more than 50% of the total pore volume, and the amorphous carbon coating content is 1-5wt%. The preparation method involves preparing emulsion slurry containing dispersant and carbon source precursor, spray drying in three temperature areas to form shell, pore forming, solidification and shaping, and carbonizing at high temperature. The application solves the problems of volume expansion and interface side reaction of the silicon-based negative electrode, provides effective buffer space while ensuring high tap density, and improves the cycle stability and volume energy density of the lithium ion battery.

Inventors

  • WANG RONGSHENG
  • CHENG YURU
  • HE GUANGYUAN
  • WANG WEI
  • LAI LIANG
  • TIAN TAO
  • WANG LIAN
  • CHEN XINGYANG
  • LI FUDONG
  • ZENG YANG

Assignees

  • 四川海创尚纬新能源科技有限公司

Dates

Publication Date
20260508
Application Date
20260209

Claims (10)

  1. 1. The spherical artificial graphite composite particle is characterized by having a spherical structure with a compact shell and communicated pores inside, and is prepared from the following raw materials in parts by weight: 88-95 parts of artificial graphite; 3-10 parts of silicon-based active material; 1-5 parts of a conductive agent; the liquid-phase binder system comprises a solvent, a dispersing agent and a carbon source precursor, wherein the carbon source precursor is added in an amount such that the content of the amorphous carbon coating in the final composite particle is 1-5wt%; The composite particles are internally provided with micron-sized pores with pore diameters distributed in the range of 0.5-3 mu m, and the pore volume of the micron-sized pores accounts for more than 50% of the total pore volume.
  2. 2. The spherical artificial graphite composite particles according to claim 1, wherein the artificial graphite is primary particles with a median particle diameter D50 of 8-12 microns, the silicon-based active material is selected from nano silicon powder or silicon monoxide, the median particle diameter D50 is 80-3 microns, and the conductive agent is selected from multi-walled carbon nanotubes, vapor grown carbon fibers and conductive carbon black.
  3. 3. The spherical artificial graphite composite particle according to claim 1, wherein the carbon source precursor is selected from phenolic resin, polyacrylonitrile, sucrose, pitch or epoxy resin, the solvent is selected from water, absolute ethyl alcohol, methanol, acetone, dimethylformamide or N-methylpyrrolidone, and the dispersing agent is selected from polyvinylpyrrolidone or sodium alginate.
  4. 4. The spherical artificial graphite composite particles according to claim 1, wherein the composite particles have a tap density of 1.20g/cm 3 to 1.32g/cm 3 , a specific surface area of 2.0m 2 /g to 4.0m 2 /g, and a total specific pore volume of 0.20mL/g to 0.35mL/g.
  5. 5. A spray-drying process for preparing spherical artificial graphite composite particles according to any one of claims 1 to 4, comprising the steps of: Dissolving a carbon source precursor in the aqueous phase solution or the oil phase solution; Dispersing artificial graphite, a silicon-based active material and a conductive agent in the aqueous phase solution or the oil phase solution to form a solid-liquid suspension, then adding the other phase solution under a shearing condition, and emulsifying to form an oil-in-water or water-in-oil emulsion slurry; The emulsion slurry is input into a pressure type spray drying tower provided with three independent temperature areas for granulation to obtain a spherical precursor, wherein the three independent temperature areas are a high-temperature rapid forming area, a middle-layer phase separation and pore canal formation area and a lower-layer solidification shaping area from top to bottom in sequence; And (3) placing the spherical precursor in an inert atmosphere furnace for high-temperature carbonization treatment to obtain the spherical artificial graphite composite particles.
  6. 6. The spray-drying process of spherical artificial graphite composite particles according to claim 5, wherein the inlet air temperature of the high-temperature rapid prototyping zone is set to 200 ℃ to 260 ℃, the temperature of the middle-layer phase separation and tunnel formation zone is set to 120 ℃ to 180 ℃, and the outlet air temperature of the lower-layer solidification and shaping zone is set to 80 ℃ to 120 ℃.
  7. 7. The spray-drying method for preparing spherical artificial graphite composite particles according to claim 5, wherein the shearing condition has a shearing rotation speed of 4000 to 6000 rpm and a shearing time of 30 to 60 minutes.
  8. 8. The spray-drying process for preparing spherical artificial graphite composite particles according to claim 5, wherein the high-temperature carbonization treatment comprises two stages: The first stage is to raise the temperature to 300-450 ℃ and keep the temperature for 2-4 hours; the second stage is to raise the temperature to 800-1200 deg.c and maintain the temperature for 4-8 hr.
  9. 9. The spray drying preparation method of the spherical artificial graphite composite particles according to claim 5, wherein the aqueous phase solution is a polyvinylpyrrolidone aqueous solution or a sodium alginate aqueous solution, and the oil phase solution is a phenolic resin ethanol solution or a mixed solution of dimethylformamide and acetone of polyacrylonitrile.
  10. 10. Use of a spherical artificial graphite composite particle according to any one of claims 1-4 in the preparation of a negative electrode sheet of a lithium ion battery or a lithium ion battery.

Description

Spherical artificial graphite composite particles and spray drying preparation method and application thereof Technical Field The invention relates to the technical field of battery cathode materials, in particular to spherical artificial graphite composite particles, a spray drying preparation method and application thereof. Background With the rapid development of new energy automobiles and portable electronic devices, the market has put higher demands on the energy density and cycle life of lithium ion batteries. Artificial graphite is used as a commercial negative electrode material which is mainstream at present, and the theoretical specific capacity of the artificial graphite limits the further improvement of the energy density of the battery. Silicon-based materials, which have a theoretical specific capacity far higher than that of graphite, are considered as important development directions for next-generation high-energy-density anode materials. Silicon-carbon composite materials combine the high capacity of silicon with the conductivity and stability of carbon materials, and are the current research focus. However, silicon-based materials still face serious challenges in practical applications. Silicon undergoes great volume expansion during lithium intercalation, and this repeated volume change causes pulverization and breakage of active material particles, and peeling of the active material from a current collector or a conductive network, resulting in rapid degradation of battery capacity. In order to solve this problem, the prior art schemes generally adopt strategies such as nanocrystallization, porosification or carbon coating. Although the porous structure can provide a certain buffer space for the volume expansion of silicon, the existing porous silicon-carbon material is difficult to combine the buffer effect and the volume energy density of the material. Conventional porous structures typically contain a large number of open nanoscale micropores, which can result in an excessive specific surface area of the material. The larger specific surface area increases the contact area of the anode material and the electrolyte, resulting in excessive consumption of active lithium when forming a solid electrolyte interface film in the first charge and discharge process, thereby reducing the first coulombic efficiency of the battery. In addition, too loose a porous structure can result in a material with a lower tap density, which makes it difficult to meet the pole piece compaction requirements of high volume energy density batteries. On the other hand, simple surface coating modification is difficult to keep structural integrity when the internal silicon particles are severely swelled, and once the coating layer is broken, the internal exposed fresh surface can continuously undergo side reaction with electrolyte, so that SEI film is continuously thickened and impedance is increased. Disclosure of Invention Aiming at the defects of the prior art, the invention provides spherical artificial graphite composite particles, a spray drying preparation method and application thereof, and solves the problems of poor cycling stability caused by severe volume expansion in the charging and discharging process of the traditional silicon-based anode material, low first coulombic efficiency and insufficient volume energy density caused by large specific surface area and low tap density of a conventional porous buffer structure. In a first aspect, the present invention provides a spherical artificial graphite composite particle, which adopts the following technical scheme: a spherical artificial graphite composite particle with a compact shell and a spherical structure containing communicated pores inside is prepared from 88-95 parts of artificial graphite, 3-10 parts of silicon-based active material, 1-5 parts of conductive agent and a liquid-phase binder system, wherein the liquid-phase binder system contains a solvent, a dispersing agent and a carbon source precursor, the addition amount of the carbon source precursor is such that the content of an amorphous carbon coating in the final composite particle is 1-5 wt%, micron-sized pores with the pore diameter distribution in the range of 0.5-3 mu m are arranged inside the composite particle, and the pore volume of the micron-sized pores accounts for more than 50% of the total pore volume. By adopting the technical scheme, the comprehensive performance of the silicon-carbon negative electrode can be improved by adopting the structural design of combining specific pore distribution with the compact shell and constructing the amorphous carbon conductive network in situ through the carbon source precursor under a liquid phase system. The specific action mechanism is as follows: And constructing an externally compact and internally porous gradient structure. The shell compact layer can effectively reduce the direct contact area of the composite particles and the ele