CN113120886A - Method for preparing graphene with different properties and application - Google Patents

Method for preparing graphene with different properties and application Download PDF

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CN113120886A
CN113120886A CN202110589864.1A CN202110589864A CN113120886A CN 113120886 A CN113120886 A CN 113120886A CN 202110589864 A CN202110589864 A CN 202110589864A CN 113120886 A CN113120886 A CN 113120886A
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graphene
filter cake
temperature
different properties
thermal reduction
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CN113120886B (en
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方钢
徐阳
张晨
瞿研
郭冰
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Jiangsu Jiangnan Elenyl Graphene Technology Co ltd
Sixth Element Changzhou Meterials Technology Co ltd
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Jiangsu Jiangnan Elenyl Graphene Technology Co ltd
Sixth Element Changzhou Meterials Technology Co ltd
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Abstract

The invention provides a method for preparing graphene with different performances and application thereof, wherein the method comprises an oxidation process and a thermal reduction process, and the thermal reduction process comprises the following steps: graphene products with different properties are prepared by adjusting and controlling technological parameters of a thermal reduction process, wherein the technological parameters comprise reduction temperature or/and time, the properties are represented by index parameters, and the index parameters comprise oxygen content or/and specific surface area. According to the invention, graphene products with different specific surface areas are prepared by regulating and controlling the technological parameters of graphene oxide in the thermal reduction process, so that the graphene oxide can be applied to different downstream fields.

Description

Method for preparing graphene with different properties and application
Technical Field
The invention relates to the technical field of material synthesis, in particular to a method for preparing graphene with different properties and application thereof.
Background
Graphene is a two-dimensional nanomaterial structure of a hexagonal honeycomb lattice consisting of only carbon atoms. Since the discovery, it has attracted extensive attention and research due to its excellent mechanical, optical, electrical, and thermal properties. The material integrates a plurality of excellent properties, and has important application prospect in the fields of electronic information, energy functional materials, energy conservation, environmental protection, biological medicine and the like. In recent years, graphene products gradually appear in the living field of people, and from daily necessities such as graphene masks and underwear to graphene lithium ion batteries, polymer composites, supercapacitors, heat dissipation films and the like, graphene falls to the ground from laboratories to markets. The graphene has been gradually industrially prepared and applied in various aspects such as conductive additives, heat-conducting films, polymer composite reinforcement and anticorrosive coatings.
Graphene can be classified into two major categories, namely powder and thin film, according to the difference of the macroscopic morphology of graphene. The graphene powder refers to disordered aggregates of nano-sized and micron-sized graphene sheets, and is mainly prepared by a liquid phase stripping method, an oxidation-reduction method and other methods. The graphene film is a continuous graphene material which grows on the surface of a specific substrate or is transferred to other substrates after growth and formation, has partial structural defects due to the limitation of a preparation process in a microscopic view, has a size reaching a centimeter or even meter magnitude in a macroscopic view, and is mainly prepared by a chemical vapor deposition method, a mechanical stripping method and the like. Compared with graphene powder, the film has the advantages of continuity and thickness uniformity, and can represent excellent physical and chemical properties of graphene. These several methods have their own advantages and applications.
The mass production of high-quality graphene materials with low cost is a precondition for realizing the industrialization of graphene application. At present, the preparation of graphene can be roughly classified into two technical routes, one is a top-down method, namely, the graphene is obtained from graphite, and the other is a bottom-up method, namely, the graphene is prepared from carbon-containing compounds. Among them, the redox method in the top-down method has the advantages of macro preparation, low cost, strong reliability and the like, and is the mainstream method for industrially preparing graphene. The quality of the graphene product is closely related to its downstream applications. Therefore, how to manage the performance of the graphene product according to the demand of different downstream applications is a key to solve the industrialization and application problems of the graphene product.
Disclosure of Invention
In view of one or more of the problems of the prior art, according to an aspect of the present invention, there is provided a method for preparing graphene with different properties, comprising an oxidation process and a thermal reduction process, the thermal reduction process comprising:
graphene products with different properties are prepared by adjusting and controlling technological parameters of a thermal reduction process, wherein the technological parameters comprise reduction temperature or/and time, the properties are represented by index parameters, and the index parameters comprise oxygen content or/and specific surface area.
Optionally, the step of preparing graphene products with different properties by adjusting and controlling process parameters of the thermal reduction process includes:
and preparing graphene products with different specific surface areas by regulating and controlling the reduction temperature in the thermal reduction process.
Optionally, the step of preparing graphene products with different specific surface areas by regulating and controlling the reduction temperature of the thermal reduction process comprises:
introducing inert gas into the oven at a set gas flow rate, setting the reduction temperature within a set temperature range, and maintaining the first set time until the temperature in the oven is uniform;
weighing the dried GO filter cake with the first set mass, pouring the dried GO filter cake into a crucible of an oven, and obtaining preliminarily reduced graphene powder through a thermal reduction process in a second set time.
Optionally, the step of preparing graphene products with different specific surface areas by regulating and controlling the reduction temperature of the thermal reduction process comprises:
passing nitrogen gas through the oven, the flow rate of the nitrogen gas being maintained at 5cm3Min, setting the reduction temperature at 180-;
and (3) pouring 6 +/-0.1 g of the dried GO filter cake obtained in the step (1) into a crucible of an oven, and performing a thermal reduction process for 10-20min to obtain preliminarily reduced graphene powder.
Optionally, the thermal reduction process further comprises the step of preparing a dried GO filter cake, the step of preparing a dried GO filter cake comprising:
taking a filter cake with solid content within a set solid content range, and crushing the filter cake by using a crusher to obtain GO filter cake particles within a set size range;
placing the GO filter cake particles in a blast oven to perform drying treatment for a set drying time within a set drying temperature range, and obtaining a dried GO filter cake with a water content within a set water content range.
Optionally, the step of preparing the dried GO filter cake comprises:
taking GO filter cakes with the solid content of 42% -50%, and crushing the GO filter cakes by a crusher to obtain GO filter cake particles with the size of 1-3 cm;
and (3) placing the crushed GO filter cake in a forced air oven for drying treatment, wherein the drying temperature is set to be 50-65 ℃, and the drying time is 10-18h, so that the dried GO filter cake with the water content of 1% -3% is obtained.
Optionally, the step of preparing graphene products with different properties by adjusting and controlling process parameters of the thermal reduction process further includes:
and calcining the graphene powder at high temperature to obtain graphene products with different properties.
Optionally, the step of calcining the graphene powder at a high temperature to obtain graphene products with different properties further includes:
weighing the graphene powder with the second set mass, putting the graphene powder into a corundum crucible, putting the corundum crucible into a calcining furnace, raising the temperature of the calcining furnace from room temperature to a set temperature threshold at a set rate, then maintaining the temperature threshold for a third set time, and naturally cooling, wherein the whole calcining process is carried out under the protection environment of inert gas.
Optionally, the step of calcining the graphene powder at a high temperature to obtain graphene products with different properties further includes:
weighing 10 +/-0.1 g of the graphene powder subjected to primary reduction, putting the graphene powder into a corundum crucible, putting the corundum crucible into a calcining furnace, heating the temperature of the calcining furnace from room temperature to 1000 ℃ at a speed of 20 ℃/min, then maintaining the temperature at 1000 ℃ for 2h, and then naturally cooling, wherein the whole calcining process is carried out under the protection of nitrogen.
Optionally, the step of preparing graphene products with different properties by adjusting and controlling process parameters of the thermal reduction process includes:
and taking the technological parameters of the thermal reduction process as input, taking the index parameters of the graphene product as output, performing curve fitting, and regulating and controlling the technological parameters according to the index parameters.
Optionally, the process parameters of the thermal reduction process are used as input, the index parameters of the graphene product are used as output, and the step of performing curve fitting includes:
curve fitting is performed with the reduction temperature as input and the specific surface area as output.
Optionally, the thermal reduction process comprises:
drying the GO filter cake to obtain a dry filter cake;
preparing graphene powder by adjusting and controlling technological parameters of a thermal reduction process;
and calcining the graphene powder at high temperature to obtain graphene products with different properties.
Optionally, the reduction process further comprises:
determining the performance of the graphene product according to the dispersion requirement of the application of the graphene product;
and determining the technological parameters of the thermal reduction process according to the performance of the graphene product.
Optionally, the indicator parameter further comprises porosity.
According to another aspect of the present invention, the graphene product obtained by the method for preparing graphene with different properties is used as a conductive additive, preferably, the graphene powder has a high specific surface area; preferably, the specific surface area of the graphene powder is more than 543m2/g。
According to the third aspect of the invention, the graphene product obtained by the method for preparing graphene with different properties is used as a heat conducting additive,preferably, the specific surface area of the graphene powder is relatively low; preferably, the specific surface area of the graphene powder is less than 287m2/g。
According to the invention, graphene products with different specific surface areas are prepared by regulating and controlling the technological parameters of graphene oxide in the thermal reduction process, so that the graphene oxide can be applied to different downstream fields.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic diagram of a flow diagram of a process for preparing graphene of different properties;
FIG. 2 is a schematic view showing the correspondence between reduction temperature and specific surface area;
FIG. 3 is an SEM image of a graphene product obtained in the first example;
fig. 4 is an SEM image of the graphene product obtained in example two;
fig. 5 is an SEM image of the graphene product obtained in example three;
fig. 6 is an SEM image of the graphene product obtained in example four;
fig. 7 is an SEM image of the graphene product obtained in example five;
fig. 8 is an SEM image of the graphene product obtained in example six;
fig. 9 is an SEM image of the graphene product obtained in example seven.
Detailed Description
In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.
The preparation of graphene by a redox method mainly comprises two processes: firstly, in the oxidation process, chemical stripping and modification of oxidation functional groups are carried out on raw material graphite by using a strong oxidant such as potassium permanganate under a solvent environment system such as concentrated sulfuric acid, and finally Graphene Oxide (GO) with functional groups such as hydroxyl, carboxyl and epoxy carried on a sheet layer is obtained; and secondly, in the thermal reduction process, the functional groups are removed in a thermal reduction disproportionation reaction mode, and finally the graphene with good interlayer stripping effect is obtained. From the aspect of the process of preparing graphene by the redox method, two factors are involved in the final graphene quality: on the one hand, the properties of graphene oxide, such as oxygen content, sheet diameter, exfoliation degree, and the like; another aspect is the thermal reduction process, including temperature, time, etc. parameters. The two factors jointly determine the performance of the prepared graphene, including important index parameters such as oxygen content, specific surface area and the like.
In one embodiment, a method for preparing graphene of different properties, comprises:
in the oxidation process, graphene oxide with different properties is prepared by regulating and controlling process parameters of the oxidation process, wherein the process parameters comprise oxidant content, oxidation temperature, oxidation time and the like, and index parameters of the properties comprise oxygen content, sheet diameter, stripping degree and the like;
and in the thermal reduction process, graphene powder with different properties is prepared by regulating and controlling process parameters of the thermal reduction process, wherein the process parameters comprise reduction temperature or/and time, the properties are represented by index parameters, and the index parameters comprise oxygen content or/and specific surface area.
The thermal reduction process directly affects the performance of the graphene product, so preferably, the oxidation process is not regulated, and the thermal reduction process is regulated to produce graphene products with different performances.
In order to improve the popularity and controllability of the graphene product in the downstream application process, graphene powder with different properties is prepared by adopting a method of thermal reduction process parameters of graphene oxide. As shown in fig. 2, graphene powder samples with different specific surface areas are obtained by controlling the temperature conditions of the thermal reduction process of graphene oxide, so as to realize controllable preparation of the performance of graphene products. The data show that the specific surface area of the prepared graphene product can be effectively controlled by controlling the temperature of the graphene oxide in the thermal reduction process. Therefore, the regulated and controlled technological parameter of the thermal reduction process is mainly the reduction temperature; graphene products with different properties are mainly specific surface area.
In one embodiment, the method for preparing graphene with different properties based on a process for preparing graphene by a redox method includes: firstly, drying GO filter cakes to obtain filter cakes in a dry state, changing the temperature condition of thermal reduction to obtain graphene powder with different properties, and then performing a high-temperature calcination process to obtain graphene products with different properties. The thermal reduction process from GO to graphene mainly comprises a disproportionation reaction, wherein oxygen-containing functional groups in GO sheet layers are reduced under the action of heat to generate small molecular gases, such as carbon dioxide, carbon monoxide, water vapor and the like. These small molecule gases counteract the inter-layer van der waals interactions, increasing the inter-graphene layer spacing. Meanwhile, the removal of oxygen-containing functional groups in the sheet layer can bring away part of carbon atoms, so that part of structural defects and the like appear between layers.
In the downstream application process of the graphene product, the specific surface area of the graphene product is a very critical factor, different index requirements are often met in different application fields, and the difference of the specific surface area causes the difference of the dispersion form of the graphene product in a matrix, so that the actual use performance is influenced. For example, in the conductive paste for the lithium ion battery, graphene is used as a conductive additive, and a higher specific surface is often required, so that the graphene can be fully peeled off after being dispersed in solvents such as NMP, and the graphene can play a role in connecting and conducting in active substances, and the resistivity of a pole piece of the conductive paste is greatly reduced. In the field of heat-conducting polymers, the requirement on the dispersion degree of graphene is not very high, and attention is paid to the difficulty of adding heat-conducting particles into a polymer matrix, so that graphene with a low specific surface is often needed and can be conveniently added into resin. In addition, in the lithium battery cathode material field, there is severer demand to the ratio table of graphite alkene microballon, and both easily add, will play certain electrically conductive effect again, consequently require to restrict very strictly to the ratio table of graphite alkene material, need carry out reasonable management and control according to different process conditions to can exert its excellent properties.
According to the invention, the graphene product with the specific surface area is prepared by changing the temperature condition in the thermal reduction process, so that the method is suitable for different downstream application occasions. The process is simple to operate, is mainly realized by regulating and controlling the temperature condition of the reduction process, does not need additional equipment or other harsh conditions, can develop graphene products with different specific surface areas according to the application requirements of the rear end, and realizes the optimization of the downstream application process.
In one embodiment, as shown in fig. 1, a method for preparing graphene with different properties comprises:
and step S1, preparing a dried GO filter cake, taking the GO filter cake with the solid content of 42-50%, and crushing by using a crusher to obtain GO filter cake particles with the size of about 1-3 cm. And (3) placing the crushed GO filter cake in a forced air oven for drying treatment, wherein the drying temperature is set to be 50-65 ℃, and the drying time is 10-18h, so that the dried GO filter cake with the water content (water content is about 1% -3% of the total mass) is obtained.
Step S2, preparing reduced graphene powder, and passing nitrogen through an oven, wherein the flow rate of the nitrogen is kept at 5cm3And/min, setting the reduction temperature to a specific temperature (180 ℃ C.) and maintaining the temperature for 15min to be uniform. Drying the powder obtained in the step (1)6 + -0.1 g of GO filter cake in the oven. And then carrying out a thermal reduction process for 10-20min to obtain the primarily reduced graphene powder.
And step S3, calcining and reducing graphene powder at high temperature, weighing 10 +/-0.1 g of the obtained graphene powder, putting the graphene powder into a corundum crucible, placing the corundum crucible into a calcining furnace, raising the temperature of the calcining furnace from room temperature to 1000 ℃ at the speed of 20 ℃/min, maintaining the temperature at 1000 ℃ for 2h, and naturally cooling. The whole calcining process is carried out under the protection of nitrogen.
In the method for preparing graphene with different properties, the properties of the intermediate product (the primarily reduced graphene powder) obtained at different reduction temperatures are different, and the intermediate product is subjected to high-temperature calcination to obtain samples (graphene products) with different specific surface areas.
The test methods in the following examples: the thermal reduction equipment is a blast oven, and the model is fine-macro-DHG-9246A; the BET test equipment used was a Quantachrome specific surface area Analyzer, model NOVA4200 e.
The first embodiment is as follows:
taking the GO filter cake with the solid content of 44%, and crushing the GO filter cake into filter cake particles with the size of 1-2cm by a crusher. And (3) placing the particles in an oven at 55 ℃ for drying treatment for 10h to obtain a dried GO filter cake with the water content of 1.8%. Setting the temperature of the oven at 180 ℃, and introducing nitrogen with the flow rate of 5cm3And/min, maintaining for 15 min. And then placing the dried GO filter cake in a crucible of an oven for thermal reduction, and keeping for 15min to finally obtain reduced graphene powder. And finally, weighing 10.05g of reduced graphene powder, placing the reduced graphene powder in a graphite crucible, calcining the reduced graphene powder for 2 hours at 1000 ℃, and naturally cooling to obtain a final graphene powder product. The specific surface area of the alloy was measured to be 287.21m2In terms of/g, as shown in FIG. 3.
Example two:
taking GO filter cake with solid content of 42%, and crushing the GO filter cake into filter cake particles with the size of 1.5-2.5cm by a crusher. Placing the granules at 60 deg.CAnd (5) drying in an oven for 15h to obtain a dried GO filter cake with a water content of 1.2%. Setting the temperature of the oven at 190 ℃, and introducing nitrogen with the flow rate of 5cm3And/min, maintaining for 20 min. And then placing the dried GO filter cake in a crucible of an oven for thermal reduction, and keeping for 20min to finally obtain reduced graphene powder. And finally, weighing 10.1g of reduced graphene powder, placing the reduced graphene powder in a graphite crucible, calcining the reduced graphene powder for 2 hours at 1000 ℃, and naturally cooling to obtain a final graphene powder product. The specific surface area of the alloy was measured to be 306.43m2The/g is shown in FIG. 4.
Example three:
taking the GO filter cake with the solid content of 50%, and crushing the GO filter cake into filter cake particles with the size of 2-3cm by a crusher. And (3) placing the particles in a 60 ℃ oven for drying treatment for 20h to obtain a dried GO filter cake with the water content of 1%. Setting the temperature of the oven at 200 ℃, and introducing nitrogen with the flow rate of 5cm3And/min, maintaining for 15 min. And then placing the dried GO filter cake in a crucible of an oven for thermal reduction, and keeping for 18min to finally obtain reduced graphene powder. And finally, weighing 10.00g of reduced graphene powder, placing the reduced graphene powder in a graphite crucible, calcining the reduced graphene powder for 2 hours at 1000 ℃, and naturally cooling to obtain a final graphene powder product. The specific surface area of the alloy was measured to be 315.29m2In terms of/g, as shown in FIG. 5.
Example four:
and taking the GO filter cake with the solid content of 40%, and crushing the GO filter cake into filter cake particles with the size of 2-3cm by a crusher. And (3) placing the particles in an oven at 60 ℃ for drying treatment for 20h to obtain a dried GO filter cake with the water content of 2.0%. Setting the temperature of the oven at 210 ℃, and introducing nitrogen with the flow rate of 5cm3And/min, maintaining for 15 min. And then placing the dried GO filter cake in a crucible of an oven for thermal reduction, and keeping for 17min to finally obtain reduced graphene powder. And finally, weighing 10.05g of reduced graphene powder, placing the reduced graphene powder in a graphite crucible, calcining the reduced graphene powder for 2 hours at 1000 ℃, and naturally cooling to obtain a final graphene powder product. The specific surface area of the alloy was measured to be 376.58m2In terms of/g, as shown in FIG. 6.
Example five:
taking GO filter cake with solid content of 49%, and crushing the GO filter cake into filter cake particles with the size of 2-3cm by a crusher. And (3) placing the particles in an oven at 60 ℃ for drying treatment for 20h to obtain a dried GO filter cake with the water content of 2.0%. Setting the temperature of the oven at 210 ℃, and introducing nitrogen with the flow rate of 5cm3And/min, maintaining for 15 min. And then placing the dried GO filter cake in a crucible of an oven for thermal reduction, and keeping for 19min to finally obtain reduced graphene powder. And finally, weighing 10.09g of reduced graphene powder, placing the reduced graphene powder in a graphite crucible, calcining the reduced graphene powder for 2 hours at 1000 ℃, and naturally cooling to obtain a final graphene powder product. The specific surface area of the alloy was measured to be 444.22m2(ii) in terms of/g, as shown in FIG. 7.
Example six:
and taking the GO filter cake with the solid content of 47%, and crushing the GO filter cake into filter cake particles with the size of 2-3cm by a crusher. The particles were placed in a 60 ℃ oven for drying treatment for 18h to obtain a dried GO filter cake with a water content of 1.7%. Setting the temperature of the oven at 230 ℃, and introducing nitrogen with the flow rate of 5cm3And/min, maintaining for 15 min. And then placing the dried GO filter cake in a crucible of an oven for thermal reduction, and keeping for 17min to finally obtain reduced graphene powder. And finally, weighing 9.94g of reduced graphene powder, placing the reduced graphene powder in a graphite crucible, calcining the reduced graphene powder for 2 hours at 1000 ℃, and naturally cooling to obtain a final graphene powder product. The specific surface area of the alloy was measured to be 505.47m2(ii) in terms of/g, as shown in FIG. 8.
Example seven:
taking the GO filter cake with the solid content of 45%, and crushing the GO filter cake into filter cake particles with the size of 2-3cm by a crusher. And (3) placing the particles in an oven at 60 ℃ for drying treatment for 20h to obtain a dried GO filter cake with the water content of 2.0%. Setting the temperature of the oven at 240 ℃, and introducing nitrogen with the flow rate of 5cm3And/min, maintaining for 15 min. And then placing the dried GO filter cake in a crucible of an oven for thermal reduction, and keeping for 20min to finally obtain reduced graphene powder. Finally weighing 9.90g of reduced graphene powder, placing the reduced graphene powder in a graphite crucible, calcining the reduced graphene powder for 2 hours at 1000 ℃, and then calcining the reduced graphene powderAnd naturally cooling to obtain the final graphene powder product. The specific surface area of the alloy was measured to be 543.47m2(ii) in terms of/g, as shown in FIG. 9.
The invention provides a method for controlling the thermal reduction temperature to control the specific surface area of graphene, develops graphene with different properties suitable for application occasions, and realizes effective application of graphene at the rear end. The graphene powder with high specific surface area is prepared by applying the graphene powder to lithium ion conductive slurry, and can be well dispersed in the slurry, so that the high conductivity of the graphene conductive additive is exerted. The graphene microspheres applied to the anode material are used for preparing the graphene powder with low specific surface area (the graphene product in the form of powder after high-temperature calcination), the set porosity (the higher the BET is, the higher the corresponding porosity is) is kept among the layers, and the effective permeation and transmission of ions are ensured on the premise that the addition is easy in the processing process.
As described above, according to the embodiments of the present invention, various changes and modifications can be made by those skilled in the art without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the contents of the specification, and must be determined according to the scope of the claims.

Claims (11)

1. A method for preparing graphene with different properties, comprising an oxidation process and a thermal reduction process, wherein the thermal reduction process comprises:
graphene products with different properties are prepared by adjusting and controlling technological parameters of a thermal reduction process, wherein the technological parameters comprise reduction temperature or/and time, the properties are represented by index parameters, and the index parameters comprise oxygen content or/and specific surface area.
2. The method for preparing graphene with different properties according to claim 1, wherein the step of preparing graphene products with different properties by adjusting and controlling process parameters of the thermal reduction process comprises the following steps:
preparing graphene products with different specific surface areas by regulating and controlling the reduction temperature in the thermal reduction process;
preferably, the step of preparing graphene products with different specific surface areas by adjusting and controlling the reduction temperature of the thermal reduction process comprises:
introducing inert gas into the oven at a set gas flow rate, setting the reduction temperature within a set temperature range, and maintaining the first set time until the temperature in the oven is uniform;
weighing the dried GO filter cake with the first set mass, pouring the dried GO filter cake into a crucible of an oven, and obtaining preliminarily reduced graphene powder through a thermal reduction process in a second set time.
3. The method for preparing graphene with different properties according to claim 2, wherein the step of preparing graphene products with different specific surface areas by adjusting and controlling the reduction temperature of the thermal reduction process comprises the following steps:
passing nitrogen gas through the oven, the flow rate of the nitrogen gas being maintained at 5cm3Min, setting the reduction temperature at 180-;
and (3) pouring 6 +/-0.1 g of the dried GO filter cake obtained in the step (1) into a crucible of an oven, and performing a thermal reduction process for 10-20min to obtain preliminarily reduced graphene powder.
4. The method of claim 1, wherein the thermal reduction process further comprises a step of preparing a dried GO filter cake, the step of preparing a dried GO filter cake comprising:
taking a filter cake with solid content within a set solid content range, and crushing the filter cake by using a crusher to obtain GO filter cake particles within a set size range;
placing the GO filter cake particles in a blast oven to perform drying treatment within a set drying temperature range for a set drying time to obtain a dried GO filter cake with a water content within a set water content range;
preferably, the step of preparing the dried GO filter cake comprises:
taking GO filter cakes with the solid content of 42% -50%, and crushing the GO filter cakes by a crusher to obtain GO filter cake particles with the size of 1-3 cm;
and (3) placing the crushed GO filter cake in a forced air oven for drying treatment, wherein the drying temperature is set to be 50-65 ℃, and the drying time is 10-18h, so that the dried GO filter cake with the water content of 1% -3% is obtained.
5. The method for preparing graphene with different properties according to claim 2, wherein the step of preparing graphene products with different properties by adjusting and controlling process parameters of the thermal reduction process further comprises:
carrying out high-temperature calcination on the graphene powder to obtain graphene products with different properties;
preferably, the step of calcining the graphene powder at a high temperature to obtain graphene products with different properties includes:
weighing the graphene powder with the second set mass, putting the graphene powder into a corundum crucible, putting the corundum crucible into a calcining furnace, raising the temperature of the calcining furnace from room temperature to a set temperature threshold at a set rate, then maintaining the temperature threshold for a third set time, and naturally cooling, wherein the whole calcining process is carried out under the protection environment of inert gas.
6. The method for preparing graphene with different properties according to claim 5, wherein the step of calcining the graphene powder at high temperature to obtain graphene products with different properties further comprises:
weighing 10 +/-0.1 g of the graphene powder subjected to primary reduction, putting the graphene powder into a corundum crucible, putting the corundum crucible into a calcining furnace, heating the temperature of the calcining furnace from room temperature to 1000 ℃ at a speed of 20 ℃/min, then maintaining the temperature at 1000 ℃ for 2h, and then naturally cooling, wherein the whole calcining process is carried out under the protection of nitrogen.
7. The method for preparing graphene with different properties according to claim 1, wherein the step of preparing graphene products with different properties by adjusting and controlling process parameters of the thermal reduction process comprises the following steps:
taking the technological parameters of the thermal reduction process as input, taking the index parameters of the graphene product as output, performing curve fitting, and regulating and controlling the technological parameters according to the index parameters;
preferably, the process parameters of the thermal reduction process are used as input, the index parameters of the graphene product are used as output, and the step of performing curve fitting includes:
curve fitting is performed with the reduction temperature as input and the specific surface area as output.
8. The method for preparing graphene with different properties according to claim 1, wherein the thermal reduction process comprises:
drying the GO filter cake to obtain a dry filter cake;
preparing graphene powder by adjusting and controlling technological parameters of a thermal reduction process;
and calcining the graphene powder at high temperature to obtain graphene products with different properties.
9. The method for preparing graphene with different properties according to claim 1, wherein the reduction process further comprises:
determining the performance of the graphene product according to the dispersion requirement of the application of the graphene product;
and determining the technological parameters of the thermal reduction process according to the performance of the graphene product.
10. The graphene product obtained by the method for preparing graphene with different properties according to any one of claims 1 to 9 is used as a conductive additive, preferably, the graphene powder has a high specific surface area; preferably, the specific surface area of the graphene powder is more than 543m2/g。
11. The graphene product obtained by the method for preparing graphene with different properties according to any one of claims 1 to 9 is used as a heat conducting additive, and preferably, the graphene powder has a low specific surface area; preferably, the specific surface area of the graphene powder is less than 287m2/g。
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