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Graphene-coated silicon composite negative electrode material and its preparation method and application

A technology of graphene coating and negative electrode materials, which is applied in the direction of battery electrodes, structural parts, electrical components, etc., can solve the problems of high cost, distance from the theoretical capacity of silicon, complex operation, etc., to achieve improved conductivity, low cost, and material The effect of structural stability

Active Publication Date: 2019-07-16
SHANGHAI JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, these methods are more complicated to operate, and the cost is relatively high. Although the obtained composite material has excellent performance, there is still a relatively large gap from the theoretical capacity of silicon.

Method used

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  • Graphene-coated silicon composite negative electrode material and its preparation method and application
  • Graphene-coated silicon composite negative electrode material and its preparation method and application
  • Graphene-coated silicon composite negative electrode material and its preparation method and application

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preparation example Construction

[0033] The preparation method of graphite oxide among the present invention is as follows:

[0034] In a water bath at 0-20°C, add 3-5g of graphite powder into 100-150mL of concentrated sulfuric acid, add 10-20g of potassium permanganate while stirring, stir for 3-4 hours, and when the temperature rises to 30-35°C, add 300-500mL Deionized water, stirred for 1-3 hours, added 15-25mL of 30% hydrogen peroxide solution, stirred for 5-20 minutes, centrifuged, washed repeatedly with 5% hydrochloric acid solution and deionized water, and dried Finally, graphite oxide is obtained.

[0035] The assembly and testing methods of lithium-ion batteries are as follows:

[0036]The pea-shaped graphene-coated silicon composite negative electrode material of the present invention and 20wt.% binder (solid content is 2wt.% styrene-butadiene rubber-sodium carboxymethyl cellulose emulsion or concentration is 0.02g / mL poly N-methylpyrrolidone solution of vinylidene fluoride) mixed with 20wt.% cond...

Embodiment 1

[0039] This embodiment relates to a preparation method of a pea-shaped graphene-coated silicon composite negative electrode material, the method comprising the following steps:

[0040] Disperse 80mg of nano-silica powder with a particle size of about 20nm and 40mg of graphite oxide powder in 20ml of deionized water. After ultrasonic dispersion, freeze-dry at -50°C and a pressure of 5Pa for 36 hours, and then disperse the dried sample in 40ml In anhydrous ethanol, put it in a polytetrafluoroethylene-lined reactor for solvothermal reaction, the reaction temperature is 170 ° C, react for 12 hours, the product after the reaction is washed with deionized water, at -50 ° C, the pressure is 5Pa Freeze-dried for 24 hours to obtain a pea-shaped graphene-coated silicon composite negative electrode material. In the composite material, the mass proportion of silicon nanoparticles is about 83%.

[0041] The SEM image of the pea-shaped graphene-coated silicon composite negative electrode ...

Embodiment 2

[0047] This embodiment relates to a preparation method of a pea-shaped graphene-coated silicon composite negative electrode material, the method comprising the following steps:

[0048] Disperse 80mg of nano-silica powder with a particle size of about 1nm and 10mg of graphite oxide powder in 50ml of deionized water. After ultrasonic dispersion, freeze-dry at 10°C and a pressure of 101000Pa for 72 hours, and then disperse the dried sample in 10ml of N , in N-dimethylformamide, placed in a polytetrafluoroethylene-lined reactor for solvothermal reaction, the reaction temperature is 240 ° C, reacted for 2 hours, the product after the reaction was washed with deionized water, at 10 ° C , freeze-dried for 72 hours at a pressure of 101,000 Pa to obtain a pea-shaped graphene-coated silicon composite. In the composite material, the mass ratio of silicon nanoparticles is about 95%.

[0049] The pea-shaped graphene-coated silicon composite negative electrode material prepared in this ex...

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Abstract

The invention provides a graphene-silicon-coated composite negative electrode material and a preparing method and application thereof.The graphene-silicon-coated composite negative electrode material comprises a cavity structure formed by graphene and nanometer silicon particles coated with the cavity structure, the particle size of the nanometer silicon particles is 1 nm-100 nm, and the weight percent of the nanometer silicon particles is 5%-95%.The preparing method includes the steps that graphene oxide and silica powder are dispersed into deionized water, and the mixture is mixed to be even under the ultrasonic condition and subjected to frozen drying; the frozen-dried product is subjected to aftertreatment to obtain the graphene-silicon-coated composite negative electrode material.The negative electrode material can be applied to a lithium ion battery.The graphene-silicon-coated composite negative electrode material has the advantages that the synthesized pea-shaped graphene-silicon-coated composite negative electrode material is applied to the lithium ion battery, the first discharging capacity is up to 3,215 mAh / g, the first coulombic efficiency is 74%, and the excellent cycling performance and the excellent rate performance are shown.

Description

technical field [0001] The invention relates to a graphene-coated silicon composite negative electrode material and its preparation method and application, belonging to the field of new energy materials and its preparation. Background technique [0002] Because of its ultra-high theoretical lithium storage capacity (4140mAh / g) and abundant resources, silicon materials are considered to have the most potential to replace graphite as the anode material for a new generation of lithium-ion batteries to meet the growing needs of portable electronics, electric vehicles, and portable electronics. There is an urgent need for higher energy density and higher power density in renewable energy storage. [0003] However, silicon particles are lithiated (forming Li x Si) and delithiation (returning to elemental Si) will undergo severe pulverization to form tiny particles. In addition, the conductivity of silicon particles is relatively poor, and more discontinuous small particles are f...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/583H01M4/62H01M4/38H01M4/36H01M10/0525
CPCH01M4/366H01M4/386H01M4/583H01M4/625H01M10/0525Y02E60/10
Inventor 马晶晶何雨石张维民马紫峰
Owner SHANGHAI JIAOTONG UNIV