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Graphene-based silicon carbon composite material and preparation method thereof

A silicon-carbon composite material and composite material technology, applied in the field of lithium-ion batteries, can solve the problems of negative electrode volume expansion and poor cycle performance, and achieve the effects of buffering volume expansion, high specific capacity, and excellent cycle performance

Inactive Publication Date: 2019-03-29
SHAANXI COAL & CHEM TECH INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to solve the problem of serious volume expansion and poor cycle performance of silicon materials applied to the negative electrode of power lithium-ion batteries, and to provide a graphene-based silicon-carbon composite material and its preparation method

Method used

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  • Graphene-based silicon carbon composite material and preparation method thereof
  • Graphene-based silicon carbon composite material and preparation method thereof
  • Graphene-based silicon carbon composite material and preparation method thereof

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preparation example Construction

[0075] See figure 1 , The method for preparing the aforementioned silicon-based composite negative electrode material includes the following steps:

[0076] 1) Using precipitation co-distillation method to coat the surface of graphene oxide and nano silicon particles with oppositely charged organic polymer layers:

[0077] a) Ultrasonic dispersion of graphene oxide into ethanol to obtain a mixed solution; according to the ratio of graphene oxide to MPS mass ratio of 1:(1~5), MPS is added to the mixed solution, heated, stirred, centrifuged / re-dispersed 1. Wash and purify to obtain MPS modified GO, namely GO-MPS;

[0078] b) The GO-MPS obtained in step a) was ultrasonically dispersed into acetonitrile, and then the ratio of GO-MPS, monomer, crosslinking agent and initiator was 1g: (1~2)mL: (0.5~2)mL: (0.015~0.12) g of monomer, crosslinking agent and initiator are added separately, and the temperature is controlled to reflux to obtain GO@polymer composite material with an organic polym...

Embodiment 1

[0095] (1) See figure 1 , 0.5g of graphene oxide (GO) was added to 250mL of absolute ethanol, and dispersed by ultrasound, after adding 1.0g of methacryloxypropyltrimethoxysilane (MPS), at 50℃ Stir for 48h. After centrifugation / re-dispersion, washing and purification three times, GO modified with MPS was obtained, labeled GO-MPS.

[0096] The obtained 0.5 g of GO-MPS was ultrasonically dispersed in 100 mL of acetonitrile, 0.75 mL of Vim, 0.75 mL of ethylene glycol dimethacrylate (EGDMA) were added, and 0.05 g of azobisisobutyronitrile (AIBN) was added to The initiator was refluxed at 100°C for 1.5 hours to obtain GO@PVim composite microspheres with positive charges on the surface.

[0097] (2) Disperse 0.5 g of silicon balls with a diameter of about 50 nm into 95 mL of absolute ethanol, add 5 mL of 25% ammonia water under stirring, and then slowly add 7.5 g of MPS to the above silicon suspension, stir for 20 hours, and use alcohol Wash it three times with water to obtain Si-MPS p...

Embodiment 2

[0107] (1) 0.25 g of GO was added to 250 mL of ethanol and dispersed by ultrasound, after adding 0.25 g of MPS, stirring was carried out at 30° C. for 24 h. After centrifugation / re-dispersion, washing and purification three times, GO modified with MPS was obtained, labeled GO-MPS.

[0108] The obtained 0.25g of GO-MPS was ultrasonically dispersed in 143mL of acetonitrile, 0.25mL of VPA, 0.125mL of EGDMA, and 0.00375g of AIBN were added respectively, and refluxed at 90℃ for 1.0h to obtain a negatively charged composite GO@ PVPA.

[0109] (2) Disperse 0.5 g of silicon balls with a diameter of about 50 nm into 475 mL of anhydrous ethanol solution, add 25 mL of 25% ammonia water under stirring, and then slowly add 5.0 g of MPS to the above silicon suspension, and stir for 12 hours. Washed with alcohol and water three times each to obtain Si-MPS particles grafted with active double bonds on the surface.

[0110] The obtained 0.5g Si-MPS particles were ultrasonically dispersed in 290mL a...

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Abstract

The invention relates to a graphene-based silicon carbon composite material and a preparation method thereof, and the preparation method comprises the following steps: respectively coating the surfaces of graphene oxide and nano silicon particles with organic polymer layers with opposite charges by adopting a precipitation co-distillation method to obtain a GO@poly composite material and a Si@polycomposite material; respectively ultrasonically dispersing the GO@poly composite material and the Si@poly composite material into water, uniformly mixing the composite materials and water, and carrying out high-temperature treatment in an H2 / Ar atmosphere to obtain a graphene-based silicon carbon composite material. According to the composite material, surface-modified nano silicon is uniformly and firmly dispersed among graphene sheet layers with opposite charges through electrostatic attraction, and a communicated conductive carbon network is formed around the nano silicon through high-temperature pyrolysis, thereby providing an electronic channel in the charging and discharging process, and facilitating the maintaining of the structural integrity of the negative electrode active material. The prepared composite material is high in specific capacity, excellent in cycle performance and long in service life of the lithium ion battery.

Description

Technical field [0001] The invention belongs to the technical field of lithium ion batteries, and specifically relates to a graphene-based silicon-carbon composite material and a preparation method thereof. Background technique [0002] In recent years, as the energy density of lithium-ion batteries continues to increase, the application of high-capacity anode and cathode materials is imperative. Among them, silicon anode, as the most mature high-capacity anode material, has attracted widespread attention. The specific capacity of pure silicon anode material can reach 4200mAh / g, which is a very ideal lithium ion battery anode material, but the application of silicon anode also faces the problem of large volume expansion. The huge volume expansion will not only cause problems such as particle pulverization and electrode dropping, but also destroy the SEI film on the electrode surface, causing the continuous growth of the SEI film and consuming limited Li. Therefore, improving the ...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/362H01M4/386H01M4/62H01M4/625H01M4/628H01M10/0525Y02E60/10
Inventor 沈晓辉田占元邵乐袁丽只胡朝文曹国林
Owner SHAANXI COAL & CHEM TECH INST
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