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Graphene with high density and high electrochemical specific capacity, as well as preparation method and application thereof

A graphene and electrochemical technology, applied in the field of graphene preparation, can solve the problems of limited graphene volume specific capacity, difficulty in preparing density, and low product density, so as to improve the mass specific electrochemical capacity, avoid graphene loss, increase Agglomeration effect

Active Publication Date: 2017-10-13
WUHAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although this type of method improves the mass specific capacity of graphene to a certain extent, the loss of graphene is serious, resulting in lower product density, so the improvement of graphene volume specific capacity is very limited.
The second is to increase the mass specific capacity of graphene materials by doping graphene with N, P, B, S, etc., but the density of the prepared doped graphene is often low
However, its mass specific capacity is limited, and the prepared graphene film containing non-volatile liquid is difficult to apply to the active material powder coating process for the preparation of existing supercapacitors and batteries.
It can be seen that it is still difficult to prepare graphene powder materials with high density and high electrochemical capacity in the existing technology

Method used

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  • Graphene with high density and high electrochemical specific capacity, as well as preparation method and application thereof
  • Graphene with high density and high electrochemical specific capacity, as well as preparation method and application thereof
  • Graphene with high density and high electrochemical specific capacity, as well as preparation method and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Prepare sulfuric acid intercalated graphite oxide according to the literature method and expand and exfoliate at 300°C to prepare expanded graphene: mix 80mL concentrated sulfuric acid and 1g sodium nitrate in an ice-water bath, stir for 10min, add 2g graphite powder (3000 mesh), stir for 1h, slowly Add 6g of potassium permanganate, stir for 20min, transfer to a 37°C water bath and stir for 10h, then add 150mL of deionized water at room temperature, stir for 0.5h, continue to add water to 500mL, add 30% hydrogen peroxide, until the cloudy liquid turns bright yellow, After stirring for 2 hours, let it stand overnight, remove the supernatant, wash with deionized water for 4 times, dry and obtain sulfuric acid intercalated graphite oxide with a sulfur content of 4 wt%, and then expand the sulfuric acid intercalated graphite oxide at 300°C Peel off to obtain expanded graphene with a rolling density of about 0.38g / cm 3 .

[0033] The obtained expanded graphene is placed in ...

Embodiment 2

[0036] Prepare expanded graphene by the method of embodiment 1, the gained expanded graphene is placed in molten CH under the protection of inert atmosphere 3 In COSK, conduct solid-liquid separation after heat treatment at 200°C for 300 minutes, wash the product with deionized water until neutral after cooling, and dry it in a blast drying oven at 50°C to obtain a tap density of about 1.1g / cm 3 high-density graphene.

[0037] Figure 5 The SEM image of the high-density graphene product prepared in Example 2 shows that the separated sheets in the expanded graphene raw material have densely overlapped together. The above SEM image shows that the graphene raw material with loose and well-developed pore structure is transformed into very dense micron-scale graphene particles after high temperature treatment in ionic liquid. The S content of high-density graphene is about 5.3% as measured by XPS. Image 6 When the high-density graphene (DSG) product prepared for Example 2 is us...

Embodiment 3

[0039] Prepare graphene oxide and chemically reduce graphene according to the literature method: mix 80mL concentrated sulfuric acid and 1g sodium nitrate in an ice-water bath, stir for 10min, add 2g graphite powder (3000 mesh), stir for 1h, slowly add 6g potassium permanganate , stirred for 20 minutes, transferred to a 37°C water bath and stirred for 10 hours, then added 150mL deionized water at room temperature, continued to stir for 0.5h, added water to 500mL, and then added 30% hydrogen peroxide until the cloudy liquid was bright yellow, stirred for 2 hours and left for a while In the evening, remove the supernatant, centrifuge and wash 15 times with 2% dilute hydrochloric acid, ultrasonically disperse in aqueous solution, and reduce with hydrazine hydrate to obtain chemically reduced graphene, whose roll density is about 0.6g / cm 3 .

[0040] The obtained chemically reduced graphene was placed in molten sodium borohydride under the protection of an inert atmosphere, and so...

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Abstract

The invention discloses graphene with high density and high electrochemical specific capacity, as well as a preparation method and application thereof. The preparation method comprises the following steps: putting low-density graphene into ionic liquid, performing heat treatment at 100 to 450 DEG C for more than 1 hour, then performing solid liquid separation, cooling, washing the product with deionized water until the pH value is 7, and finally putting into a blast drying box and drying to obtain the graphene with high density and high electrochemical specific capacity, wherein the ionic liquid is liquid of one or more of inorganic acid, inorganic alkali, inorganic salt and organic salt. In the compacting process of the graphene, the graphene is doped with heterotopic atoms, the plane of the graphene is subjected to pore formation, the density of the prepared graphene can reach above 1 g / cm<3>, the specific surface area can reach above 300 m<2> / g, and high-quality specific capacity and high-volume capacity can be shown simultaneously when being applied in the field of electrochemical energy storage.

Description

technical field [0001] The invention belongs to the technical field of graphene preparation, and relates to a high-density and high electrochemical specific volume graphene and its preparation method and application, in particular to a method for preparing high-density and high electrochemical specific volume graphene by heat-treating low-density graphene with ionic liquid method. Background technique [0002] Graphene has very broad application prospects in energy storage fields such as supercapacitors and lithium-ion batteries. At present, the most promising technology for large-scale production of graphene is the chemical redox method. The prepared graphene exhibits high mass specific capacity and lithium storage activity, but lacks practical value. The main reason is that these graphene materials are difficult to At the same time, it satisfies the two key indicators of high density and high quality specific capacity. First of all, in order to realize the high-quality s...

Claims

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Application Information

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IPC IPC(8): C01B32/194H01G11/32H01G11/86H01M4/583H01M4/62
CPCC01P2002/85C01P2004/03C01P2004/04C01P2006/11C01P2006/12C01P2006/16C01P2006/40H01G11/32H01G11/86H01M4/583H01M4/625Y02E60/10
Inventor 金先波林双王志勇
Owner WUHAN UNIV
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