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CN-121617949-B - Preparation method and application of Si@C@rGO@N@P silicon carbon composite material

CN121617949BCN 121617949 BCN121617949 BCN 121617949BCN-121617949-B

Abstract

The application relates to a preparation method and application of a Si@C@rGO@N@P silicon-carbon composite material, and belongs to the technical field of lithium ion battery anode materials. Ball milling POSS particles in a ball mill to obtain powder, adding the obtained powder into GO dispersion liquid, adding ionic liquid IL-C≡N, placing the mixed liquid obtained by ultrasonic dispersion into a high-pressure hydrothermal kettle for reaction, adding TPP into the obtained IL-POSS-GO aerogel, mixing with ultrasonic waves, drying, calcining in a tubular furnace, washing and drying to obtain the N/P co-doped porous silicon-carbon composite material Si@C@rGO@N@P. The silicon-carbon composite material is used for preparing the negative electrode material of the lithium ion battery, so that the battery is endowed with good cycle performance, higher reversible specific capacity and first coulombic efficiency, and the overall electrochemical performance is excellent.

Inventors

  • SHEN YONGMIAO
  • ZHAO FUGANG
  • ZHANG KAI
  • XI ZIWEI
  • SHEN YAFEN
  • QI HANG
  • KANG XIAOWEI
  • YIN YUYUN

Assignees

  • 浙江理工大学嵊州创新研究院有限公司
  • 绍兴市锐依博新材料技术有限公司

Dates

Publication Date
20260512
Application Date
20260203

Claims (10)

  1. 1. The preparation method of the Si@C@rGO@N@P silicon-carbon composite material is characterized by comprising the following steps of: (a) Ball milling is carried out on POSS particles to obtain POSS powder with the particle size less than or equal to 500 nm; (b) Adding POSS powder obtained in the step (a) into GO dispersion liquid, adding 1-cyanopropyl-3-methylimidazole bis (trifluoromethanesulfonyl) imide ionic liquid, and carrying out ultrasonic treatment to obtain uniform IL-POSS-GO mixed liquid; (c) Transferring the IL-POSS-GO mixed solution into a hydrothermal kettle, and performing hydrothermal reduction for 6-24 hours at 180-240 ℃ to obtain IL-POSS-GO aerogel; (d) And (3) vacuum dipping the IL-POSS-GO aerogel in a TPP solution, taking out and drying the aerogel, heating the obtained powder to 800-1500 ℃ under hydrogen and inert atmosphere, and carrying out heat preservation reaction to obtain the Si@C@rGO@N@P silicon-carbon composite material.
  2. 2. The method for preparing the Si@C@rGO@N@P silicon carbon composite material according to claim 1, wherein the POSS is at least one of octaphenyl-POSS, octamethyl-POSS, octavinyl-POSS and octaamino-POSS.
  3. 3. The preparation method of the Si@C@rGO@N@P silicon carbon composite material is characterized by comprising the step of mixing IL-POSS-GO, wherein the mass ratio of POSS to GO is 1:10-10:1.
  4. 4. The preparation method of the Si@C@rGO@N@P silicon carbon composite material is characterized by comprising the step of preparing a GO dispersion liquid with the concentration of 0.5-5 mg/mL.
  5. 5. The preparation method of the Si@C@rGO@N@P silicon carbon composite material is characterized by comprising the step of preparing a TPP solution from an ethanol solution of TPP, wherein the content of TPP is 0.1-1.0 g/L.
  6. 6. The preparation method of the Si@C@rGO@N@P silicon carbon composite material is characterized in that the inert atmosphere is any one of nitrogen, argon and hydrogen mixed gas, and the volume fraction of hydrogen in the argon and hydrogen mixed gas is 0-10%.
  7. 7. The preparation method of the Si@C@rGO@N@P silicon carbon composite material is characterized by comprising the step of heating at a rate of 2-10 ℃ per minute.
  8. 8. The preparation method of the Si@C@rGO@N@P silicon-carbon composite material is characterized by comprising the steps of carrying out acid washing, water washing and drying on a crude product obtained by heat preservation reaction to obtain the purified Si@C@rGO@N@P silicon-carbon composite material.
  9. 9. The preparation method of the Si@C@rGO@N@P silicon carbon composite material is characterized by comprising the step of pickling with 5-20wt% of hydrofluoric acid, hydrochloric acid or nitric acid for 5-30 min.
  10. 10. A si@c@rgo@n@p silicon carbon composite material as defined in claim 1 for the preparation of a lithium ion battery anode material.

Description

Preparation method and application of Si@C@rGO@N@P silicon carbon composite material Technical Field The invention relates to a preparation method and application of a Si@C@rGO@N@P silicon-carbon composite material, and belongs to the technical field of lithium ion battery anode materials. Background The application defects of the traditional silicon-carbon cathode are derived from three major cracks: (1) The silicon source and the carbon source are spatially separated in the reaction process. The conventional method is to synthesize nano Si and then coat carbon, or form porous carbon and then soak silicon, so that interface faults caused by 'later combination' can not be eliminated all the time. (2) High temperature carbonization is separated from the reduction step. SiO 2 -Si needs to be carried out at the temperature exceeding 1800 ℃ or under the condition of adding magnesium/aluminum reducer, and graphitization of the carbon skeleton needs to be carried out at an inert high temperature, so that the two-stage process of reduction reaction and high-temperature carbonization causes overgrowth of crystal grains and collapse of pore structures. (3) Volume buffering is decoupled from electron conducting network construction. The graphene is mostly introduced into the structure by physical mixing, and the conductive network is torn circle by circle due to a sliding interface in the charging and discharging process. In the prior art, molecular POSS is used as a silicon precursor, but a cage-type Si 8O12 skeleton only generates SiO 2 and free carbon under the condition of being higher than 1000 ℃ in an inert atmosphere, si can still be generated only by secondary carbothermal reduction, if H 2 is directly connected, the process is carried out under the condition of being higher than 1400 ℃, and crystal grains are rapidly grown to hundred nanometers. In other words, the three of the carbonization-reduction-confinement are not compatible, which becomes the three difficulties of the temperature-grain-interface accepted in the field. In the prior art, silicon and Graphene Oxide (GO) are often compounded, and are introduced into a carbon layer for buffering expansion through high-temperature calcination. However, when the structure is built, the traditional physical mixing is difficult to realize nano-scale dispersion of silicon, and doping elements (N, P, B and the like) are unevenly distributed, so that the improvement of the rate performance and the circulation stability is limited. Disclosure of Invention Aiming at the defects, the invention provides a preparation method of the Si@C@rGO@N@P silicon carbon composite material, which not only realizes the construction of an in-situ self-assembled ionic liquid-POSS-GO layered precursor, but also realizes the formation of the N/P co-doped porous silicon carbon anode material in the subsequent hydrothermal-calcining process. Specifically, the technical scheme adopted by the application is as follows: A preparation method of Si@C@rGO@N@P silicon-carbon composite material comprises the following steps: s1, dispersing Graphene Oxide (GO) in deionized water to form GO dispersion liquid, adding 1-cyanopropyl-3-methylimidazole bis (trifluoromethanesulfonyl) imide ionic liquid (IL-C.ident.N), performing room temperature ultrasonic treatment, then adding polyhedral oligomeric silsesquioxane (POSS) powder obtained by ball milling, continuously stirring, and performing self-assembly to construct uniform IL-POSS-GO lamellar supermolecular sol. S2, transferring the IL-POSS-GO layered supermolecular sol to a hydrothermal reaction kettle, and reacting to obtain IL-POSS-GO aerogel; S3, dipping the IL-POSS-GO aerogel in a TPP solution, and drying to obtain a phosphorus source-loaded IL-POSS-GO/TPP compound after vacuum assisted dipping; S4, calcining the IL-POSS-GO/TPP compound under the hydrogen and inert atmosphere, and performing thermal insulation reaction to enable POSS to be subjected to in-situ carbothermal reduction to generate Si@C nanocrystalline, so as to obtain a Si@C@rGO@N@P crude product; S5, carrying out acid washing, water washing and drying on the crude product to obtain the N/P co-doped purified Si@C@rGO@N@P silicon-carbon composite material. In the scheme, GO is a three-in-one carrier of a conductive framework, a buffer air cushion and a chemical anchor point, and the three-in-one carrier has a triple identity in the preparation system of the application, wherein (1) a flexible framework is formed by constructing a three-dimensional conductive network in advance on a two-dimensional sheet layer, and the three-dimensional conductive network becomes rGO after high-temperature graphitization, so that a continuous electronic channel is provided for the whole electrode, and a later-stage additional conductive agent is omitted. (2) The interlayer spacing is propped up to 0.37-0.40 nm by the Si@C nanometer island to form a reversible spring cavity, the volume expansion is