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Graphene and fabrication method thereof and super capacitor

A graphene and nanographite flake technology, applied in graphene, hybrid capacitor electrodes, nanocarbons, etc., can solve the problems of poor conductivity, low energy density of activated carbon, and low energy density

Active Publication Date: 2013-04-03
NINGBO GRAPHENE INNOVATION CENT CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, activated carbon has a low energy density and can only be used in aqueous electrolytes, while 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF) with a working voltage of up to 4V 4 ) When used in ionic liquid electrolytes, it has the following disadvantages: the conductivity is poor, and most of the pores are distributed inside the particles. Under high current charge and discharge, the diffusion of ions in the tortuous activated carbon pores is hindered, and the specific capacity drops rapidly.
However, the tap density of graphene prepared by thermal expansion method is only 0.005m 2 / g, the energy density calculated based on the volume is low, because graphene is easy to agglomerate during the preparation and use process, and the specific surface area utilization rate is low, so it is not conducive to practical application

Method used

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  • Graphene and fabrication method thereof and super capacitor
  • Graphene and fabrication method thereof and super capacitor
  • Graphene and fabrication method thereof and super capacitor

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preparation example Construction

[0033] The invention provides a preparation method of graphene, comprising the following steps: A) ball milling expanded graphite to obtain nano-graphite flakes with a thickness of 15-200 nm; B) oxidizing the nano-graphene flakes to obtain partially oxidized Graphene; the carbon-to-oxygen ratio of the partially oxidized graphene is 20:1 to 3:1; C) mixing the partially oxidized graphene with a first activator, heating for the first pore forming to obtain micropores Graphene; D) The microporous graphene is mixed with a second activator, and heated to form holes for the second time to obtain graphene.

[0034] Wherein, the expanded graphite can be the expanded graphite well-known to those skilled in the art, and there is no special limitation. The expanded graphite in the present invention is preferably expanded graphite with a size of 50-300 μm, more preferably 100-200 μm. After the expanded graphite is ball milled, flake graphite with a nanometer thickness is obtained, and the...

Embodiment 1

[0057] 1.1 Mill 5 g of expanded graphite with a size of 50 μm in a ball mill at 300 r / min for 5 hours to obtain graphite nanosheets with a thickness of 100 nm.

[0058] 1.2 Mix 5g of nano-graphite flakes obtained in 1.1, 87.5ml of concentrated hydrochloric acid and 45ml of concentrated nitric acid, then slowly add 45g of potassium chlorate, and react for 24 hours in an ice-water bath to obtain partially oxidized graphene, which is repeatedly washed with deionized water Wash to neutral pH.

[0059] 1.3 After fully impregnating 5g of partially oxidized graphene obtained in 1.2 in 0.5mol / L oxalic acid solution, heat it in a tube furnace to 500°C for low temperature expansion for 20s, and mix the expanded graphene with potassium hydroxide according to the mass After mixing evenly at a ratio of 1:6, heat to 600°C for 12 hours in a tube furnace containing water vapor and nitrogen atmosphere to obtain microporous graphene.

[0060] 1.4 After the microporous graphene obtained in 1.3 ...

Embodiment 2

[0072] 2.1 5 g of expanded graphite with a size of 50 μm was ball-milled for 24 hours in a ball mill under the condition of 200 r / min to obtain graphite nanosheets with a thickness of 15 nm.

[0073] 2.2 Mix 5g of nano-graphite flakes obtained in 2.1, 87.5ml of concentrated hydrochloric acid and 45ml of concentrated nitric acid, then slowly add 45g of sodium chlorate, and react for 48h under the condition of an ice-water bath to obtain partially oxidized graphene, which is deionized Water was washed repeatedly until the pH was neutral.

[0074] 2.3 After fully impregnating 5g of partially oxidized graphene obtained in 2.2 in 1mol / L oxalic acid solution, heat it in a tube furnace to 600°C for low temperature expansion for 30s, and mix the expanded graphene and potassium hydroxide according to the mass ratio After mixing evenly at a ratio of 1:8, heat to 900°C for 5 hours in a tube furnace containing water vapor and nitrogen atmosphere to obtain microporous graphene.

[0075] 2...

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Abstract

The invention provides graphene and a fabrication method thereof. The fabrication method comprises the steps of obtaining a nano graphite flake by ball-milling of expanded graphite, obtaining partially oxidized graphene by oxidizing, mixing the partially oxidized graphene with a first activator, obtaining micropore graphene by heating and conducting pore-forming for the first time, mixing the micropore graphene with a second activator, and obtaining the graphene by heating and conducting pore-forming for the second time. Compared with the prior art, the graphene with a central pore structure is obtained by taking the expanded graphite as a raw material through weak oxidation and two pore-forming processes. Firstly, the expanded graphite is taken as the raw material and subjected to the ball-milling to be uniformly dispersed, the nano graphite flake with a thinner lamellar structure is obtained, the expansion pore-forming is conducted on the nano graphite flake, and the graphene with a three-dimensional lamellar structure, the central pore structure and a higher specific surface area is finally obtained; and secondly, the weak oxidization is conducted on the nano graphite flake, and the graphene with a short-rang order and long-range disorder structure and a higher tap density at a macro level is finally fabricated.

Description

technical field [0001] The invention belongs to the technical field of organic semiconductor materials, and in particular relates to graphene, a preparation method thereof, and a supercapacitor. Background technique [0002] With the continuous expansion of the information society and the emergence of environmental and energy crises, the issue of energy storage and conversion efficiency is becoming more and more important. In various energy conversion systems, supercapacitors are used in backup power supplies, start-up power supplies, pulse power supplies, power grids, etc. areas of balance. According to different energy storage mechanisms, supercapacitors can be divided into electric double layer capacitors and pseudocapacitors or redox capacitors. Electric double-layer capacitors mainly rely on the electric double layer at the interface between the electrode and the electrolyte to store charges, and use the huge specific surface area of ​​the electrode material to store ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B31/04H01G11/24H01G11/36C01B32/184
CPCY02E60/13
Inventor 周旭峰刘兆平郑超王国华
Owner NINGBO GRAPHENE INNOVATION CENT CO LTD
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