WO2019196144A1

WO2019196144A1 - Method for preparing graphene by intercalation of alkali metal

Info

Publication number: WO2019196144A1
Application number: PCT/CN2018/085135
Authority: WO
Inventors: 李彬; 杨树斌
Original assignee: 北京航空航天大学
Priority date: 2018-04-09
Filing date: 2018-04-28
Publication date: 2019-10-17
Also published as: CN110357081A

Abstract

Provided is a method for preparing graphene by intercalation of alkali metal, comprising the following steps: (1) in an inert environment, mixing a graphite-based material with alkali metal to acquire an evenly mixed graphite-based carbon material-alkali metal composite material, standing in the inert environment, and implementing a metal intercalation reaction; (2) removing the intercalation material by placing the obtained composite material into a liquid state medium capable of reacting with same and reacting, and acquiring graphene material by means of oscillation, washing, and separating. Also provided is graphene prepared using the present method. The method uses a golden yellow composite material obtained by mixing lithium or another high activity alkali metal and graphite-based carbon material and implementing an intercalation reaction as a precursor, and the subsequent preparation of graphene can be carried out in room temperature and air conditions, being suitable for the large scale preparation of graphene.

Description

Method for preparing graphene by intercalating alkali metal

Technical field

The invention belongs to the field of inorganic non-metal materials, and in particular relates to a method for preparing graphene.

Background technique

Graphene has excellent material properties, including a large specific surface area, a high Young's modulus, electron mobility, and an extremely high thermal conductivity. Graphene is composed of a single layer of sp ² hybridized carbon atoms. It is the thinnest and hardest nano carbon material known at present, and it is almost completely transparent, light in weight, excellent in flexibility and superior thermal conductivity. It has a wide range of applications in the fields of energy storage, catalysis, and composite materials.

At present, the production methods of graphene mainly include a top-down method and a bottom-up method. Bottom-up growth methods, such as traditional chemical vapor deposition methods, but chemical vapor deposition methods require graphene to grow in harsh environments, such as higher temperatures and high vacuum, and the addition of catalysts during the deposition process. Catalytic growth consumes a large amount of energy during the growth process. In addition, the growth rate of the method is slow and the production cost is greatly increased, which greatly limits the application fields of such grown graphene. Top-down methods, such as liquid phase stripping, starting from natural graphite, using a stripping method to prepare graphene oxide, and further reducing the preparation of graphene, such methods generally require higher energy or strong oxides in the preparation process. Pre-treatment, post-reduction method to prepare graphene, the graphene prepared by this method will cause many defects in the redox process, and the preparation cycle is also long.

In order to achieve large-scale preparation and commercial application of graphene, and to meet current environmental requirements, how to produce high-quality graphene in low energy consumption, large scale, environmental protection and high efficiency is still a great challenge. Opportunities for the development of graphene.

Summary of the invention

In view of the deficiencies in the art, the object of the present invention is to propose a high-efficiency method for preparing graphene by intercalating alkali metal, using graphite carbon material as raw material and metal lithium or other high active alkali metal as intercalation material. The single-layer or oligo-layer graphene is obtained by expanding the intercalated metal based on metal intercalated graphite and rapidly reacting.

Another object of the present invention is to provide graphene obtained by the production method.

The technical solution for achieving the object of the present invention is:

A method for preparing graphene by intercalating alkali metal, comprising the following steps:

(1) In an inert environment, a graphite-based material and an alkali metal are mixed to obtain a uniformly mixed graphite-based carbon material-alkali metal composite material, and allowed to stand in an inert environment to cause a metal intercalation reaction until the composite material From black to golden yellow;

(2) The obtained composite material is placed in a liquid medium capable of reacting therewith to carry out a reaction, the intercalation material is removed, and the graphene material is obtained by shaking, washing and separating.

Wherein, the alkali metal is one or more of lithium, sodium and potassium; the graphite material may be natural graphite or artificial graphite, specifically graphite paper, graphite powder, flake graphite, expanded graphite, spherical graphite One or more of highly oriented pyrolytic graphite.

Further, the mass ratio of the graphite material to the alkali metal in the step (1) is 1 to 10:1; the graphite material and the alkali metal are mixed and repeatedly folded and rolled until the mixture is uniformly mixed; or the alkali metal is melted by heating and then added. The graphite material is stirred and mixed evenly.

Wherein, in the step (1), the inert environment is an argon atmosphere and/or a helium atmosphere, and is allowed to stand in an inert environment until the graphite turns golden yellow, generally 10 hours or more, and can be placed in an inert environment all the time. Further changes.

Wherein, in the step (2), the liquid medium is one or more of water, methanol, ethanol, propanol, n-butanol, ethylene glycol, formic acid, acetic acid, propionic acid and hydrochloric acid.

The oscillation in the step (2) may be ultrasonic vibration.

For the operation in which the liquid medium is a hydrochloric acid solution, the concentration of hydrochloric acid may be, but not limited to, 0.05 to 0.5 mol/L.

An optional technical solution of the present invention is that after the step (1), the operation is performed:

Transferring the obtained golden-yellow composite material to a non-inert environment for a period of time, the golden yellow color of the above composite material is completely removed;

The non-inert environment is one or more of air, nitrogen, carbon dioxide, ammonia, water vapor, argon-organic acid mixture, and argon-organic alcohol mixture.

After the step (1), the operation is performed: the obtained composite material is placed in a container, and one of water vapor, argon-acetic acid mixed gas and argon-ethanol mixed gas is slowly introduced into the container. The golden yellow color of the composite material is completely removed, and the composite material is taken out, and the step (2) is carried out.

The mass ratio of acetic acid or ethanol in the mixed gas may be 1-20%.

The obtained graphene has the following features: the graphene layer has a thickness of 1-10 layers and a lateral dimension of 0.2-100 μm.

The graphene obtained by the method of the present invention is prepared.

The beneficial effects of the invention are:

In the preparation method of the high-quality graphene of the invention, the gold-yellow composite material after intercalation reaction of lithium or other high-activity alkali metal and graphite-based carbon material is used as a precursor, and the preparation of graphene in the later stage can be at room temperature. It is carried out under conditions of air and the like, and is suitable for the preparation of graphene on a large scale. The preparation method of the present invention abandons the conventional high-pollution preparation method of the redox agent, and the high-energy preparation method such as mechanical shearing and arc discharge, and the method for processing the intercalated metal by intercalating reaction of lithium and graphite-based carbon materials The high-quality graphene is obtained, the method has high yield of graphene, the obtained graphene product has high single layer rate, and the preparation method is fast and efficient, low in energy consumption and small in pollution, and is suitable for industrial large-scale production.

DRAWINGS

Figure 1 is an optical photograph of the graphite powder-lithium composite prepared in Example 1 after standing in an inert environment for 24 hours.

2 is an XRD diffraction pattern of the graphite powder-lithium composite material prepared in Example 1 after standing in an inert environment for 24 hours.

3 is a scanning electron micrograph of graphene obtained in Example 1.

4 is a scanning electron micrograph of graphene obtained in Example 4.

Fig. 5 is an atomic force microscope photograph of graphene obtained in Example 1.

detailed description

The technical solution of the present invention will be described below by way of specific examples. It should be understood that one or more of the steps referred to in the present invention does not exclude other methods and steps that exist before and after the combination of steps, or that other methods and steps can be inserted between the steps specifically mentioned. It is also to be understood that the examples are not intended to limit the scope of the invention. Unless otherwise stated, the numbering of each method step is only for the purpose of identifying each method step, and does not limit the order of each method or the scope of implementation of the invention, and the relative relationship changes or adjustments, without substantial technical content changes. The conditions under which the invention can be implemented are also considered to be within the scope of the invention.

The materials and apparatus used in the examples are not particularly limited in their source, and are commercially available or prepared according to a conventional method well known to those skilled in the art.

Example 1:

(1) Mixing graphite powder and metallic lithium in an inert atmosphere of argon at a mass ratio of 6:1, first melting the lithium by heating, adding graphite powder, stirring and mixing, and uniformly mixing the graphite powder and the metallic lithium. After the mixture was left in an inert atmosphere for 24 hours, the mixture was turned into golden yellow (Fig. 1);

(2) The above-mentioned golden-yellow composite material is taken out from an inert environment, placed in ethanol (analytically pure), and the intercalated metal is rapidly reacted with ethanol to form a gas, and the composite material rapidly expands and is dispersed in ethanol. After the reaction was completed, the solution was ultrasonicated for one hour, and the solution was repeatedly washed, and the graphene material was obtained by suction filtration.

The XRD diffraction pattern of the material is shown in Fig. 2, and the gold-yellow material obtained by the analysis is an alkali metal intercalated graphite. The graphene was examined by scanning electron microscopy to 10 layers with a lateral dimension of 10 microns (see Figure 3). The graphene material obtained was examined by atomic force microscopy to obtain a graphene material having a thickness of 3.5 nm (see Fig. 5).

Example 2:

(1) The flake graphite and the metallic lithium are mixed in an inert atmosphere of argon at a mass ratio of 5:1, and the rolling pressure is repeatedly folded until the flake graphite and the metallic lithium are uniformly mixed and placed in an inert atmosphere for 48 hours. The above mixture becomes golden yellow;

(2) The above-mentioned golden-yellow composite material was taken out from an inert environment, placed in a 0.1 mol/L aqueous hydrochloric acid solution, and the intercalated metal was rapidly reacted with a solution to form a gas, and the composite material rapidly expanded and dispersed in an aqueous hydrochloric acid solution. After the reaction was completed, the solution was ultrasonicated for one hour, and the solution was repeatedly washed, and the graphene material was obtained by suction filtration.

Example 3:

(1) The expanded graphite and metallic lithium are mixed in an inert atmosphere of argon at a mass ratio of 3:1, and the rolling pressure is repeatedly folded until the flake graphite and the metallic lithium are uniformly mixed and placed in an inert atmosphere for 48 hours. The above mixture becomes golden yellow;

(2) The above-mentioned golden-yellow composite material is taken out from an inert environment and placed in acetic acid (analytical grade), and the intercalated metal rapidly reacts with acetic acid to form a gas, and the composite material rapidly expands and is dispersed in acetic acid. After the reaction was completed, the solution was ultrasonicated for one hour, and the solution was repeatedly washed, and the graphene material was obtained by suction filtration.

Example 4:

(1) The flake graphite and metallic lithium are mixed in an inert atmosphere of argon at a mass ratio of 5:1, and the roll press is repeatedly folded by a roll press to uniformly mix the flake graphite and the metallic lithium, and then placed in an inert atmosphere. After 48 hours, the mixture was turned into golden yellow;

(2) The above-mentioned golden-yellow composite material is taken out from the inert environment and placed in water, and the intercalated metal rapidly reacts with water to form a gas, and the composite material rapidly expands and is dispersed in water. After the reaction was completed for 30 s, the solution was ultrasonicated for one hour, and the solution was repeatedly washed, and the graphene material was separated by suction filtration (see Fig. 4).

Comparing Examples 1-4, the composite material was placed in a different solvent such as ethanol, formic acid, acetic acid, water or dilute hydrochloric acid, and there was no significant difference in the severity of the reaction, but it was slightly slowed down as the acidity decreased.

Example 5:

(1) The graphite powder and the metallic lithium are mixed in an inert atmosphere of argon at a mass ratio of 8:1, and the rolling pressure is repeatedly folded until the graphite powder and the metallic lithium are uniformly mixed and placed in an inert atmosphere for 48 hours. The above mixture becomes golden yellow;

(2) The above-mentioned golden-yellow composite material was taken out from the inert environment, placed in a flask, and water vapor was slowly introduced into the flask, and the water vapor and the intercalated metal were slowly reacted to produce lithium hydroxide, and the volume was further expanded, after about 2 hours. take out;

(3) The above product was placed in formic acid (analytical grade), and the intercalation layer was reacted with formic acid, and the composite material was expanded and dispersed in formic acid for 30 s. After the reaction was completed, the solution was ultrasonicated for one hour, and the solution was repeatedly washed, and the graphene material was obtained by suction filtration.

Example 6

(1) The expanded graphite and the metallic lithium are mixed in an inert atmosphere of argon at a mass ratio of 10:1, and the rolling is repeatedly folded until the expanded graphite and the metallic lithium are uniformly mixed and placed in an inert atmosphere for 48 hours. The above mixture becomes golden yellow;

(2) The above-mentioned golden composite material was taken out from the inert environment, placed in a flask, and an argon-acetic acid mixed gas was slowly introduced into the flask (acetic acid was introduced with Ar, and the ratio of acetic acid to the total intake air volume was estimated. Between 1% and 10%), the acetic acid and the intercalation metal in the mixed gas slowly react with lithium acetate to further expand the volume;

(3) The above product was placed in water, and the intercalation reaction was carried out with water. After about 1 min, the composite material was expanded and dispersed in water. After the reaction was completed, the solution was ultrasonicated for one hour, and the solution was repeatedly washed, and the graphene material was obtained by suction filtration.

Example 7

(2) taking the above golden composite material out of an inert environment, placing it in a flask, and slowly introducing an argon-ethanol mixture into the flask (acetic acid accounts for between 1% and 10% of the total intake volume ratio). After the ethanol in the mixed gas reacts slowly with the intercalated metal, the volume is further expanded after the lithium ethoxide is produced;

(3) The above product is placed in water, the intercalation reacts with water, and the composite is expanded and dispersed in water. After the reaction was completed, the solution was ultrasonicated for one hour, and the solution was repeatedly washed, and the graphene material was obtained by suction filtration.

The above embodiments are merely illustrative of the specific embodiments of the present invention, and are not intended to limit the scope of the present invention, and various modifications and changes can be made by those skilled in the art based on the prior art without departing from the spirit of the invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention are intended to fall within the scope of the invention as defined by the appended claims.

Industrial applicability

The invention provides a method for preparing graphene by intercalating an alkali metal. By (1) mixing a graphite-based material and an alkali metal in an inert environment to obtain a uniformly mixed graphite-based carbon material-alkali-metal composite material, and allowing to stand in an inert environment to cause a metal intercalation reaction, (2 The obtained composite material is placed in a liquid medium capable of reacting therewith to carry out a reaction, the intercalation material is removed, and the graphene material is obtained by shaking, washing and separating. In the method for preparing high-quality graphene provided by the present invention, high-quality graphene is obtained by intercalating a lithium metal and a graphite-based carbon material to obtain a high-quality graphene, and the obtained graphene has high yield and obtained graphite. The olefin product has a high single layer rate, and the preparation method is fast and efficient, low in energy consumption and small in pollution, and is suitable for industrial large-scale production, and has good economic value and application prospect.

Claims

A method for preparing graphene by intercalating an alkali metal, comprising the steps of:

(1) In an inert environment, a graphite-based raw material and an alkali metal are mixed to obtain a graphite-alkali metal mixed material, and allowed to stand in an inert environment to cause a metal intercalation reaction of the graphite until the composite material changes from black to gold. yellow;

(2) The obtained composite material is placed in a liquid medium capable of reacting therewith to carry out a reaction, the intercalation material is removed, and the graphene is obtained by shaking, washing and separating.
The method for preparing graphene by intercalating an alkali metal according to claim 1, wherein the alkali metal is one or more of lithium, sodium and potassium; and the graphite material is natural graphite or artificial graphite. Specifically, one or more of graphite paper, graphite powder, flake graphite, expanded graphite, spherical graphite, and highly oriented pyrolytic graphite.
The method for preparing graphene by intercalating an alkali metal according to claim 1, wherein the mass ratio of the graphite-based material to the alkali metal in the step (1) is from 1 to 10:1.
The method for preparing graphene by intercalating an alkali metal according to claim 1, wherein in the step (1), the graphite material and the alkali metal are mixed and repeatedly folded and rolled until the mixture is uniformly mixed; or the alkali metal is melted by heating and then added. The graphite material is stirred and mixed evenly.
The method for preparing graphene by intercalating an alkali metal according to claim 1, wherein in the step (1), the inert environment is an argon atmosphere and/or a helium atmosphere, and is allowed to stand in an inert environment until the sample is changed. It is golden yellow and the rest time is above 10h.
The method for preparing graphene by intercalating an alkali metal according to claim 1, wherein in the step (2), the liquid medium is water, methanol, ethanol, propanol, n-butanol, ethylene glycol or formic acid. One or more of acetic acid, propionic acid, and hydrochloric acid.
The method for preparing graphene by intercalating an alkali metal according to any one of claims 1 to 6, wherein after the step (1), the operation is performed:

Transferring the obtained golden-yellow composite material to a non-inert environment, and the golden yellow color is completely removed; the non-inert environment is air, nitrogen, carbon dioxide, ammonia, water vapor, argon-organic acid mixture, One or more of an argon-organic alcohol mixture.
The method for preparing graphene by intercalating alkali metal according to claim 7, wherein after the step (1), the operation is performed: the obtained composite material is placed in a container, and water vapor and argon are slowly introduced into the container. One of a gas-acetic acid mixed gas and an argon-ethanol mixed gas, the golden yellow color of the composite material is completely removed, and the composite material is taken out, and the step (2) is carried out.
The graphene prepared by the method according to any one of claims 1 to 8.