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Three-dimensional porous cobalt-based/graphene composite material and preparation method thereof

A composite material, three-dimensional porous technology, applied in electrical components, battery electrodes, circuits, etc., can solve the problems of unstable material structure and performance, difficult to ensure stable product quality, and cumbersome preparation process, and achieve rich raw materials and improve circulation. Stable performance and strong controllability

Active Publication Date: 2013-11-20
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In summary, the current methods for preparing cobalt-based / graphene composites mainly have the following disadvantages: some work still uses ex-situ synthesis, resulting in unstable structure and performance of the material; the preparation process is cumbersome and not environmentally friendly, and usually requires the addition of Reducing agent and adjust the pH of the solution to obtain related products through multi-step reactions
At the same time, due to the complexity of the reaction, it is difficult to ensure stable product quality; most of the synthesized products are two-dimensional structures with nanoparticles supported on the surface of graphene, which are easy to fall off during the reaction process, and it is difficult to maintain stable performance.

Method used

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  • Three-dimensional porous cobalt-based/graphene composite material and preparation method thereof

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preparation example Construction

[0035]The preparation method of graphene oxide among the present invention is as follows:

[0036] 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 After drying, graphene oxide is obtained.

[0037] The assembly and testing methods of lithium-ion batteries are as follows:

[0038] The three-dimensional porous cobalt-based / graphene composite 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.% conductive agent ...

Embodiment 1

[0041] Disperse 50mg of graphene oxide and 250mg of cobalt acetate tetrahydrate (about 60mg of cobalt element) in 50mL of absolute ethanol, ultrasonically disperse it for 45 minutes to make it uniform, and then put the mixed solution into the reaction kettle through 190°C solvothermal After 20 hours of reaction, freeze-dry for 24 hours at -80 ° C and a pressure of 5 Pa to obtain a three-dimensional porous cobalt-based / graphene composite material. The cobalt-based component in this material is mainly a mixture of simple cobalt and cobaltous oxide. The particle size of the cobalt-based material is 500nm, the proportion of the cobalt-based material in the composite material is 80%, and the pore diameter of the porous material is about 6 μm.

[0042] The three-dimensional porous cobalt-based / graphene composite material of the prepared lithium-ion battery was assembled into a battery for charge and discharge tests. The first charge and discharge Coulombic efficiency was 72%, and the...

Embodiment 2

[0045] Disperse 100mg of graphene oxide and 125mg of cobalt acetate tetrahydrate (about 30mg of cobalt element) in 50mL of absolute ethanol, and disperse it evenly by ultrasonication for 60 minutes, then put the mixed solution into the reaction kettle and undergo solvothermal heating at 180°C. After 20 hours of reaction, freeze-dry for 18 hours at -70°C and a pressure of 10 Pa to obtain a three-dimensional porous cobalt-based / graphene composite material. 400nm, the proportion of cobalt-based material in the composite material is 40%, and the pore diameter of the porous material is about 3 μm.

[0046] A lithium-ion battery silicon-graphene composite material prepared was assembled into a battery for charge and discharge tests. The first charge and discharge Coulombic efficiency was 65%, and the first reversible capacity was 1081mAh / g. The charge-discharge test was carried out at a current density of 200mA / g, and the reversible capacity of the 20th cycle was still 900mAh / g. Th...

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Abstract

The invention discloses a three-dimensional porous cobalt-based / graphene composite material and a preparation method thereof. The composite material mainly comprises a cobalt-based material and graphene, wherein the graphene forms a porous three-dimensional conductive network; and the cobalt-based material is coated in the conductive network to form the three-dimensional porous cobalt-based / graphene composite material. The preparation method comprises the following steps of: dispersing the graphene and a cobalt salt precursor in a solvent by adopting a solvothermal in-situ one-step synthesis method; and placing in a reaction kettle for carrying out solvothermal reaction, freezing and drying to obtain the three-dimensional porous cobalt-based / graphene composite material. The composite material is used in a lithium ion battery, so that a constant-current charging and discharging test is carried out when the current density is as high as 6400mA / g, and reversible capacity after 30 circulations is still stabilized to 400mAh / g or higher. The three-dimensional porous cobalt-based / graphene composite material has the advantages of being cheap and easily available in material, low in cost, high in yield, simple and safe in operation process, environment-friendly, stable in product structure and suitable for large-scale industrial production.

Description

technical field [0001] The invention relates to a battery electrode material and a preparation method thereof, in particular to a three-dimensional porous cobalt-based / graphene composite material and a preparation method thereof. Background technique [0002] Graphene is a two-dimensional honeycomb structure composed of a single layer of atoms tightly packed, with a series of excellent properties such as large specific surface area, super conductivity, good chemical stability and wide electrochemical stability window. In recent years, researchers have found that graphene aerogels with a three-dimensional network structure synthesized by self-assembly have more excellent performance, especially the coating of transition metal oxide particles in this three-dimensional structure can greatly improve the stability of the material, Conductivity and electrochemical capacity and other properties. Wufeng Chen et al. reported on Adv.Mater.201123, 5679-5683 that the 3D graphene airgel...

Claims

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Application Information

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IPC IPC(8): H01M4/36
CPCY02E60/12Y02E60/10
Inventor 何雨石马晶晶马紫峰
Owner SHANGHAI JIAO TONG UNIV
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