CN-122025605-A - Preparation method and system of SiOx/polypyrrole/waste graphite/ternary hybrid silicon-carbon composite material

CN122025605ACN 122025605 ACN122025605 ACN 122025605ACN-122025605-A

Abstract

The invention belongs to the technical field of lithium ion battery materials, and discloses a preparation method of a SiOx/polypyrrole/waste graphite ternary hybrid silicon-carbon composite material, wherein a 'coordination-etching' dual-template method is used, a through pore carbon structure is formed by guiding an aluminum-phytic acid sacrificial layer, and the preparation method is different from the traditional processes such as physical mixing or CVD deposition, and solves the problem of poor combination of the thickness of a coating layer and an interface; the silicon-based anode material with the ternary synergistic coating structure of waste graphite, porous carbon and silicon oxide is constructed by a coordination chemistry strategy, and can be applied to occasions with requirements on high energy density and high working condition stability, such as power batteries of electric automobiles, energy storage under special extreme environments, high-power consumption electronic equipment (unmanned aerial vehicles, electric tools and the like) and the like.

Inventors

HONG JUAN
DING LU
SUN YONGGANG
YUE LU
CUI HUI
YANG BAOJU
ZHANG HONGGANG

Assignees

盐城工学院

Dates

Publication Date: 20260512
Application Date: 20260324

Claims (7)

1. The preparation method of the SiOx/polypyrrole/waste graphite ternary hybrid silicon-carbon composite material is characterized by comprising the following steps of: S1, physical regeneration and normalization treatment of waste graphite; s2, dispersing an aluminum source, a conductive polymer monomer and SiOx powder in a mixed solvent of deionized water and alcohol in sequence under an ice bath condition, then adding waste graphite treated in the step S1, and carrying out ultrasonic treatment to obtain a mixed solution A1 which is uniformly mixed; S3, preparing an organic coordination acid solution, dripping the organic coordination acid solution into the A1 solution obtained in the step S2 for reaction, and enabling metal ions to have coordination effect with the organic coordination acid, so that a coordination connection structure is formed between SiOx particles and waste graphite, and obtaining an intermediate solution A2 after the reaction is finished; s4, adding an initiator into the solution A2, and performing polymerization reaction under the ice bath condition of 0-5 ℃ to generate a primary sample A3; and S5, carrying out high-temperature calcination on the A3 sample obtained in the step S4 under inert atmosphere after centrifugation or suction filtration and drying, and then carrying out soaking, cleaning, suction filtration and drying by an acid solution to obtain the ternary hybrid silicon-carbon composite electrode material.
2. The method for preparing the SiOx/polypyrrole/waste graphite ternary hybrid silicon-carbon composite material according to claim 1, wherein in the step S1, waste graphite is one or a mixture of two of waste materials generated in the process of processing graphite products and graphite waste recovered and extracted from waste lithium ion batteries, and the physical regeneration and normalization treatment comprises the processes of collecting, cleaning, drying, screening and the like to purify waste graphite and screen particle size.
3. The preparation method of the SiOx/polypyrrole/waste graphite ternary hybrid silicon-carbon composite material is characterized in that in the step S2, the mass ratio of an aluminum source to a conductive polymer monomer to raw SiOx powder to pretreated waste graphite is 1 (0.5-1.0): (1.5-2.5): (0.8-1.2); In step S2, the aluminum source is selected from one or more of aluminum nitrate nonahydrate, aluminum sulfate, aluminum chloride and their respective hydrates, preferably aluminum nitrate nonahydrate; in step S2, the conductive polymer monomer is selected from one or more mixtures of pyrrole, thiophene, aniline and derivatives thereof, preferably pyrrole; in the step S2, the particle size of the original SiOx powder is 50-600 nm, the particle size of the powder is preferably 500nm, and the mixed solvent is a mixed solution of deionized water and isopropanol, wherein the mass ratio of the mixed solution is (20-30): 2.
4. The method for preparing the SiOx/polypyrrole/waste graphite ternary hybrid silicon-carbon composite material according to claim 1, wherein in the step S3, the organic coordination acid solution is a phytic acid aqueous solution with a concentration of 30% -60%, preferably 50%, and the mass ratio of the aluminum source to the organic coordination acid solution is 1 (5.0-10.0), the reaction temperature is 0-5 ℃, and the reaction time is 0.5-1 h.
5. The preparation method of the SiOx/polypyrrole/waste graphite ternary hybrid silicon-carbon composite material is characterized in that in the step S4, the initiator is at least one selected from ammonium persulfate, sodium persulfate, potassium persulfate and hydrogen peroxide, preferably ammonium persulfate, the mass ratio of the conductive polymer monomer to the initiator is 1 (2.5-3.5), the polymerization temperature is 0-5 ℃, and the reaction time is 5-9 h; in the step S5, the calcination temperature is 850-950 ℃, the calcination time is 2-4 hours, the temperature rising rate is 1-5 ℃ per minute, the protective atmosphere is nitrogen or argon, the concentration of hydrofluoric acid solution is 1% -5% in the hydrofluoric acid etching process, and the etching time is 5-45 minutes.
6. The ternary hybrid silicon-carbon composite electrode material prepared by the preparation method of the SiOx/polypyrrole/waste graphite ternary hybrid silicon-carbon composite material, as claimed in claim 1, is characterized by comprising a conductive framework formed by graphite, a porous carbon layer coated on the surface of the conductive framework, and SiOx particles dispersed and fixed in the porous carbon layer, wherein the SiOx particles form interface connection with the carbon layer and the graphite framework through a metal ion coordination derivative structure; The ternary hybrid silicon-carbon composite electrode material is internally provided with a three-dimensional communicated nano pore structure, the average pore diameter of the ternary hybrid silicon-carbon composite electrode material is 2-10 nm, the specific surface area of the ternary hybrid silicon-carbon composite electrode material is 35-45 m & g -1 , and the Raman spectrum I D /I G of the ternary hybrid silicon-carbon composite electrode material is 0.7-1.05.
7. A system for preparing a SiOx/polypyrrole/waste graphite ternary hybrid silicon-carbon composite material for implementing the preparation method of any one of claims 1-6, wherein the SiOx/polypyrrole/waste graphite ternary hybrid silicon-carbon composite material preparation system comprises: the normalization processing module is used for physical regeneration and normalization processing of the waste graphite; The dispersing module is used for dispersing an aluminum source, a conductive polymer monomer and SiOx powder in a mixed solvent of deionized water and alcohol in sequence under the ice bath condition, then adding waste graphite treated by the S1, and carrying out ultrasonic treatment to obtain a mixed solution A1 which is uniformly mixed; The preparation module is used for preparing an organic coordination acid solution, dripping the organic coordination acid solution into the A1 solution obtained in the step S2 for reaction, and enabling metal ions to have coordination effect with the organic coordination acid, so that a coordination connection structure is formed between SiOx particles and waste graphite, and an intermediate solution A2 is obtained after the reaction is finished; the polymerization module is used for adding an initiator into the solution A2, and generating a primary sample A3 after polymerization reaction under the ice bath condition of 0-5 ℃; and (3) a high-temperature calcining module, which is used for carrying out high-temperature calcining on the A3 sample obtained in the step (S4) under inert atmosphere after centrifugation or suction filtration and drying, and then carrying out soaking, cleaning, suction filtration and drying on the sample by an acid solution to obtain the ternary hybrid silicon-carbon composite electrode material.

Description

Preparation method and system of SiOx/polypyrrole/waste graphite/ternary hybrid silicon-carbon composite material Technical Field The invention belongs to the technical field of lithium ion battery materials, and particularly relates to a preparation method and a system of a SiOx/polypyrrole/waste graphite ternary hybrid silicon-carbon composite material. Background The lithium ion battery has the advantages of high energy density, long cycle life, high working voltage and the like, and is widely applied to the fields of electric automobiles, energy storage systems, portable electronic equipment and the like. Along with the continuous improvement of the requirements of application scenes on energy density and power density, the traditional graphite anode material is limited by the theoretical specific capacity (372 mAh.g -1) of the traditional graphite anode material, and the development requirement of a lithium ion battery with high energy density is difficult to meet. Silicon oxide (SiOx) has higher theoretical specific capacity and can generate in the first lithium intercalation processAndAnd buffering phases are adopted, so that the volume expansion problem is relieved to a certain extent, and the silicon-based anode material is considered to have a great application prospect. However, siOx intrinsic electron conductivity is lower, and there are still problems of large volume change, poor structural stability, etc. in the charge-discharge process, which easily lead to pulverization of active particles, destruction of electrode conductive network, and aggravation of interface side reaction, thereby causing increase of charge transfer impedance, decrease of cycle stability, and decrease of rate capability. In order to improve the circulation stability of the silicon-based material, the prior art is mainly regulated and controlled by a nano structure design or a carbon material composite coating mode. Although nanocrystallization can relieve mechanical stress caused by volume change, the larger specific surface area of the nano-composite material is easy to cause the increase of electrolyte side reaction, and the tap density is lower, so that the improvement of volume energy density is not facilitated. The carbon coating strategy can improve the conductivity of the material and stabilize the structure to a certain extent, but the traditional pyrolytic carbon layer is mostly in physical contact with active substances, the interfacial binding force is limited, structural failure is easy to occur in the long-term circulation process, and meanwhile, the multi-step coating process generally has the problems of complex preparation process, high cost and the like. On the other hand, as the retired amount of power batteries and waste materials generated in the processing process of graphite products continue to grow, the recycling of waste graphite is attracting attention. The waste graphite has good conductivity and structural stability, and can be used as a conductive framework material, but the existing researches mostly adopt a simple physical composite mode, the interface combination is insufficient, and the interface impedance is difficult to effectively reduce and play a synergistic effect. In addition, polypyrrole derived carbon has the advantages of good conductivity, adjustable structure and the like, and is used for constructing a silicon-carbon composite structure, but a linear molecular stacking structure formed in the traditional polymerization process lacks space support, so that a stable and continuous coating layer is difficult to form in a multiphase composite system. Therefore, it is needed to provide a new silicon-carbon composite material structure and a preparation method thereof, which can improve the interface bonding strength between SiOx and carbon phase and between graphite substrates, construct a stable electron/ion transmission channel, and improve the cycle stability and the rate capability of the material on the premise of keeping higher specific capacity while realizing the utilization of waste graphite resources. Through the above analysis, the problems and defects existing in the prior art are as follows: (1) The linear molecular stacking structures formed during conventional polymerization lack spatial support and it is difficult to form stable and continuous coating layers in multiphase composite systems. (2) SiOx-based negative electrode materials in the prior art have poor conductivity, large volume change, insufficient interface bonding strength and low utilization efficiency of waste graphite resources. Disclosure of Invention Aiming at the problems existing in the prior art, the invention provides a preparation method of a SiOx/polypyrrole/waste graphite ternary hybrid silicon-carbon composite material. The invention is realized in such a way that the preparation method of the SiOx/polypyrrole/waste graphite ternary hybrid silicon-carbon composite material comprises the fol