CN-122025611-A - Silicon-carbon composite anode material for lithium ion battery, and preparation method and application thereof

CN122025611ACN 122025611 ACN122025611 ACN 122025611ACN-122025611-A

Abstract

The invention provides a silicon-carbon composite anode material for a lithium ion battery and a preparation method and application thereof, wherein the method comprises the steps of selecting nano silicon powder to prepare silicon powder dispersion liquid, slowly adding hydrogen peroxide solution into the silicon powder dispersion liquid, centrifugally separating, collecting precipitate, washing and drying to obtain oxidized modified nano silicon particles; dispersing oxidized modified nano silicon particles in a mixed solution of ethanol and deionized water to obtain a modified silicon dispersion liquid, adding a carbon source and a dispersing agent into the modified silicon dispersion liquid, stirring, adding a catalyst to obtain silicon-polymer composite particles, filtering, washing, drying and grinding the silicon-polymer composite particles to obtain a composite precursor, carrying out low-temperature solidification, medium-temperature pre-carbonization, high-temperature deep carbonization and pore structure shaping on the composite precursor to obtain a black solid product, soaking, washing, drying and grinding the black solid product to obtain the silicon-carbon composite anode material. The method has simple process, low cost and easy industrialized production.

Inventors

ZENG DUO
JIANG ZHIQIANG
CUI YI
GUO CHEN
YANG YUHANG
WANG LELE
BAO QIANG
YU CHANGCHUN
LAN XIAOHONG
LI JIE

Assignees

华能重庆珞璜发电有限责任公司
西安热工研究院有限公司

Dates

Publication Date: 20260512
Application Date: 20260403

Claims (10)

1. A method for preparing a silicon-carbon composite anode material for a lithium ion battery, which is characterized by comprising the following steps: Selecting nano silicon powder, adding deionized water for dispersion to obtain silicon powder dispersion liquid, slowly adding hydrogen peroxide solution into the silicon powder dispersion liquid, centrifugally separating, collecting precipitate, and washing and drying to obtain oxidized modified nano silicon particles; Dispersing the oxidized modified nano silicon particles in a mixed solution of ethanol and deionized water to obtain a modified silicon dispersion; adding a carbon source and a dispersing agent into the modified silicon dispersion liquid, stirring, adding a catalyst to enable the carbon source to perform in-situ polymerization reaction on the surfaces of the modified silicon particles to form a uniform polymer coating layer, and obtaining silicon-polymer composite particles; filtering, washing, drying and grinding the silicon-polymer composite particles to obtain a composite precursor; Sequentially carrying out low-temperature curing, medium-temperature pre-carbonization and high-temperature deep carbonization on the composite precursor and shaping a pore structure to obtain a black solid product; and soaking, washing, drying and grinding the black solid product to obtain the silicon-carbon composite anode material.
2. The method of preparing according to claim 1, wherein low temperature curing the composite precursor comprises: And placing the composite precursor in a tube furnace protected by nitrogen atmosphere, heating to 200-300 ℃ at a heating rate of 2-4 ℃ per minute, and preserving heat for 1-h-2 hours to realize crosslinking and curing of the polymer coating.
3. The method of preparing according to claim 2, wherein the intermediate-temperature pre-carbonization of the composite precursor comprises: And heating the composite precursor to 500-700 ℃ at a heating rate of 1-3 ℃ per minute, and preserving heat for 2-3 hours to realize preliminary carbonization of the polymer.
4. A method of preparing according to claim 3, wherein the subjecting the composite precursor to high temperature deep carbonization and pore structure shaping comprises: And heating the composite precursor to 800-1100 ℃ at a heating rate of 1-2 ℃ per minute, and preserving heat for 2-4 hours to realize deep carbonization of the polymer and form a porous carbon shell.
5. The method of claim 1, wherein the step of filtering, washing, drying, and grinding the silicon-polymer composite particles to obtain a composite precursor comprises: and filtering and washing the silicon-polymer composite particles, vacuum drying at 60-80 ℃ for 12-24 hours, and grinding to 100-200 meshes to obtain the composite precursor.
6. The method of claim 1, wherein adding a carbon source and a dispersant to the modified silicon dispersion, stirring, and adding a catalyst to allow the carbon source to undergo an in-situ polymerization reaction on the surface of the modified silicon particles to form a uniform polymer coating layer, thereby obtaining silicon-polymer composite particles, comprising: Adding a carbon source and a dispersing agent into the modified silicon dispersion liquid, wherein the mass ratio of the carbon source to the modified nano silicon particles is 1:1-2:1, and the using amount of the dispersing agent is 5% -10% of the mass of the carbon source; After stirring for 1-2 hours, adding a catalyst, adjusting the pH value of the system to 2-4 or 8-10, and stirring for 4-8 hours at 60-80 ℃ to enable a carbon source to perform in-situ polymerization reaction on the surfaces of the modified silicon particles to form uniform polymer coating layers, so as to obtain the silicon-polymer composite particles.
7. The preparation method of claim 1, wherein the black solid product is soaked, washed, dried and ground to obtain the silicon-carbon composite anode material, and the preparation method comprises the following steps: Placing the black solid product into 1-3 mol/L dilute hydrochloric acid solution, soaking for 4-8 hours at room temperature, and stirring to remove unreacted silicon particles and inorganic impurities; Repeatedly washing with deionized water to neutrality, and washing with absolute ethyl alcohol for 2-3 times; Vacuum drying is carried out for 12-24 hours at the temperature of 80-100 ℃, and grinding is carried out to 100-200 meshes, so that the silicon-carbon composite anode material is obtained.
8. The preparation method of claim 1, wherein nano silicon powder is selected, deionized and dispersed to obtain silicon powder dispersion, hydrogen peroxide solution is slowly added into the silicon powder dispersion, precipitate is collected after centrifugal separation and washed and dried to obtain oxidized modified nano silicon particles, and the preparation method comprises the following steps: selecting nano silicon powder with the particle size of 30-150 nm, adding the nano silicon powder into deionized water, and performing ultrasonic dispersion for 30-60 min to prepare silicon powder dispersion liquid with the concentration of 0.1-0.5 mol/L; Slowly dropwise adding a hydrogen peroxide solution into the silicon powder dispersion liquid, wherein the molar ratio of hydrogen peroxide to nano silicon powder is 1:1-2:1, and stirring for 2-4 hours at room temperature to enable the surface of the nano silicon powder to undergo a mild oxidation reaction to form a silicon oxide transition layer; After the reaction is finished, centrifugal separation is carried out for 10-20 min at the rotating speed of 5000 r-8000 r/min; And (3) collecting the precipitate, repeatedly washing the precipitate with deionized water for 3-5 times, and vacuum drying the precipitate at 80-100 ℃ for 12-24 hours to obtain the oxidized modified nano silicon particles.
9. A silicon-carbon composite negative electrode material for a lithium ion battery, characterized in that the silicon-carbon composite negative electrode material for a lithium ion battery is prepared by the preparation method of the silicon-carbon composite negative electrode material for a lithium ion battery according to any one of claims 1 to 8.
10. The silicon-carbon composite negative electrode material for a lithium ion battery of claim 9, which is applied to a negative electrode of the lithium ion battery.

Description

Silicon-carbon composite anode material for lithium ion battery, and preparation method and application thereof Technical Field The invention belongs to the technical field of preparation of silicon-carbon composite materials, and particularly relates to a silicon-carbon composite negative electrode material for a lithium ion battery, and a preparation method and application thereof. Background With the rapid development of new energy automobiles, portable electronic devices and large-scale energy storage industries, the market has put higher demands on the energy density, cycle life and rate capability of lithium ion batteries. The cathode material is used as a core component of the lithium ion battery, the comprehensive electrochemical performance of the battery is directly determined, the cathode of the commercial lithium ion battery at present mainly adopts graphite materials, but the theoretical specific capacity of the commercial lithium ion battery is only 372 mAh/g, the application requirement of the high-energy-density battery is difficult to meet, and the development of the high-capacity cathode material becomes a key of technological breakthrough of the lithium ion battery. Silicon (Si) is one of the most potential negative electrode materials of the next generation lithium ion battery due to the advantages of extremely high theoretical specific capacity (4200 mAh/g), abundant reserves, low cost, environmental friendliness and the like. The silicon negative electrode realizes the high-efficiency storage of lithium ions through alloying reaction, the lithium storage capacity of the silicon negative electrode is more than 10 times of that of a graphite material, and the energy density of the lithium ion battery can be remarkably improved. However, the silicon negative electrode still faces three major core technical bottlenecks in practical application, namely, the silicon negative electrode has a volume expansion rate of 300% -400% when silicon and lithium are subjected to alloying reaction in the charging and discharging process, the electrode material is pulverized and falls off due to severe volume deformation, the structural integrity of the electrode is destroyed, and the capacity of the battery is quickly attenuated, the silicon material is a semiconductor, the electronic conductivity is poor (the conductivity is only 10 -3-10-4 S/m), the diffusion rate of lithium ions in a silicon bulk phase is low, the rate performance of the battery is poor, the chemical property of the silicon surface is active, irreversible side reaction is easy to occur with electrolyte, an unstable Solid Electrolyte Interface (SEI) film is formed, a large amount of electrolyte and lithium ions are consumed by repeated rupture and regeneration of the SEI film, and the primary charging and discharging efficiency and the cycling stability of the battery are reduced. In order to solve the problems, the prior art mainly adopts a silicon-carbon composite modification strategy, and the volume expansion of silicon is relieved and the electronic conductivity of the material is improved by compositing silicon with a carbon material with excellent conductivity. However, the existing silicon-carbon composite anode material still has a plurality of defects that most of the composite processes adopt a simple physical mixing mode, the binding force between silicon and carbon is weak, interfacial separation is easy to occur in the charge and discharge process, volume expansion cannot be effectively buffered, a carbon layer of the partially coated silicon-carbon composite material is too thick or too thin, lithium ion transmission is blocked by the too thick carbon layer, silicon pulverization cannot be effectively inhibited by the too thin carbon layer, in addition, uniform dispersion of silicon particles is difficult to realize by the existing composite method, silicon particle aggregation is easy to cause, and the problems of volume expansion and capacity attenuation are further aggravated. Aiming at the problems, it is necessary to provide a silicon-carbon composite anode material for a lithium ion battery, a preparation method and application thereof, wherein the silicon-carbon composite anode material is reasonable in design and can effectively solve the problems. Disclosure of Invention The invention aims at solving at least one of the technical problems existing in the prior art and provides a silicon-carbon composite anode material for a lithium ion battery, and a preparation method and application thereof. One aspect of the invention provides a preparation method of a silicon-carbon composite anode material for a lithium ion battery, which comprises the following steps: Selecting nano silicon powder, adding deionized water for dispersion to obtain silicon powder dispersion liquid, slowly adding hydrogen peroxide solution into the silicon powder dispersion liquid, centrifugally separating, collecting precipitate, and washing