CN114436251A - Preparation method and application of fluorinated graphene with high thermal stability, high insulation and high thermal conductivity - Google Patents
Preparation method and application of fluorinated graphene with high thermal stability, high insulation and high thermal conductivity Download PDFInfo
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Abstract
A preparation method and application of fluorinated graphene with high thermal stability, insulation and heat conduction are disclosed, wherein the preparation method comprises the following steps: placing the dried graphene in a fluorination kettle, vacuumizing the fluorination kettle, introducing nitrogen, pumping out the nitrogen to perform multiple replacement treatments, and then heating the fluorination kettle; performing replacement treatment on the cache kettle for multiple times, and then heating to the same temperature as the fluorination kettle; introducing the fluorination reaction mixed gas into a heated buffer kettle, keeping the temperature for 10-30min, and performing thermal pre-dissociation to convert part of fluorine gas molecules in the fluorination reaction mixed gas into fluorine atoms; and introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation into the heated fluorination kettle, and carrying out fluorination reaction with the graphene for 0.5-2h to obtain the fluorinated graphene with high thermal stability, insulation and heat conductivity. The fluorinated graphene prepared by the preparation method disclosed by the invention has more uniform fluorine element distribution, so that the fluorinated graphene has a relatively uniform lattice structure, and further has excellent heat-conducting property.
Description
Technical Field
The invention relates to the technical field of fluorinated graphene and preparation thereof, in particular to a preparation method and application of fluorinated graphene with high thermal stability, insulation and high heat conductivity.
Background
With the rapid development of two-dimensional nanomaterials, graphene is one of the most promising materials due to its excellent electrical conductivity, thermal conductivity and mechanical properties. However, in the application process, the original graphene has the problems of zero energy gap, poor reaction inertia, poor dispersibility and the like, so that an effective method needs to be developed to chemically modify the graphene. Among the modification methods, a method of directly modifying graphene by fluorination using fluorine gas or a mixed gas thereof has attracted the most attention. The effective fluorination can reduce the acting force between graphene sheets and open the band gap of the graphene, thereby having interesting performances in the aspects of optics, electrics, magnetics, mechanics, catalysis, adsorption and the like. Therefore, the fluorinated graphene shows potential application prospects in the aspects of high-performance composite materials, insulating and heat conducting materials, lubricating oil additives, microwave absorption materials, photoluminescence band gap materials and the like. Particularly, recent researches show that the fluorinated graphene has certain insulating and heat conducting capacity, so that the fluorinated graphene has good application potential in the field of thermal management application.
In the prior art, the preparation methods of fluorinated graphene mainly include two major types, namely a fluorination method and a stripping method. The fluorination method mainly comprises direct gas fluorination, plasma fluorination, hydrothermal fluorination and the like. In addition to fluorine gas being selected as a fluorine source, the direct gas fluorination also uses high-activity xenon difluoride (Nano Lett.2013,13,9, 4311- -. The exfoliation method needs to perform fluorination reaction on graphite, and then the graphite is prepared by mechanical exfoliation, solvent swelling exfoliation or thermal exfoliation (Small 2010,6, No.24, 2885-2891) and the like, so that the prepared fluorinated graphene has thick lamella, uneven degree of fluorination among lamellae, low fluorine content and difficulty in large-scale application.
In conclusion, the direct fluorination method using fluorine gas as the fluorine source is most suitable for the large-scale industrial production of fluorinated graphene. However, current research shows that in the direct fluorine-based fluorination reaction process, fluorine gas reacts in the form of fluorine molecules. Due to the existence of energy barrier, the fluorination reaction tends to occur on the part of the fluorinated structure, the prepared fluorinated graphene product has a microstructure with nonuniform distribution of fluorine elements, and a multiphase structure with simultaneous existence of a fluorinated area and an aromatic area can be observed on the fluorinated graphene sheet layer by using a transmission electron microscope (Carbon 132(2018) 271-279). Due to the structure, the fluorinated graphene still retains a certain electric conduction capability, and the lattice heat conduction capability and the thermal stability of the fluorinated graphene are damaged.
Therefore, how to develop an effective fluorination means to add fluorine element to the graphene carbon skeleton structure in a more uniform form, so as to prepare fluorinated graphene with high thermal stability, high insulation and high thermal conductivity, becomes the focus of current research.
Disclosure of Invention
Based on the above, the invention provides a preparation method and application of fluorinated graphene with high thermal stability, high insulation and high thermal conductivity, so as to solve the technical problems of poor thermal stability and weak intrinsic thermal conductivity due to the fact that a fluorinated graphene product prepared by a direct fluorination method in the prior art has a microstructure with unevenly distributed fluorine elements.
In order to achieve the above object, the present invention provides a preparation method of fluorinated graphene with high thermal stability, high insulation and high thermal conductivity, comprising the following steps:
1) placing the dried graphene in a fluorination kettle, vacuumizing the fluorination kettle, introducing nitrogen and pumping out the nitrogen to perform multiple replacement treatments, and heating the fluorination kettle to 140-260 ℃;
2) performing replacement treatment on the cache kettle for multiple times as same as that in the step 1), and then heating to the temperature as that of the fluorination kettle in the step 1);
3) introducing the fluorination reaction mixed gas into the heated buffer kettle in the step 2), and keeping the temperature for 10-30min for thermal pre-dissociation so as to convert part of fluorine gas molecules in the fluorination reaction mixed gas into fluorine atoms;
4) and (3) introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation in the step 3) into the fluorination kettle heated in the step 1), and carrying out fluorination reaction with the graphene for 0.5-2h to obtain the fluorinated graphene with high thermal stability, insulation and heat conductivity.
As a further preferable technical solution of the present invention, the method further comprises the following steps before the step 1): and putting the raw material of the graphene into a vacuum oven, heating to 100 ℃, and carrying out vacuum treatment for 5-10h to obtain the dried graphene.
As a further preferable technical scheme of the present invention, the graphene is single-layer graphene, few-layer graphene, graphene oxide, reduced graphene oxide, nitrogen-doped graphene, or porous graphene, or is a graphene aerogel, a graphene fiber, or a graphene film.
In a more preferred embodiment of the present invention, the fluorination reaction mixed gas is a mixed gas of fluorine gas and inert gas, or a mixed gas of fluorine gas, inert gas and oxygen gas.
In a further preferred embodiment of the present invention, the inert gas is at least one of helium, neon, argon, krypton, xenon, nitrogen, and carbon dioxide.
In a more preferred embodiment of the present invention, the fluorine gas concentration in the fluorination reaction mixed gas is 5 to 20 v/v%.
As a further preferred technical solution of the present invention, the step 4) specifically comprises:
introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation in the step 3) into the fluorination kettle heated in the step 1) for one time or multiple times, and performing static fluorination reaction with graphene for 0.5-2 h; or continuously introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation in the step 3) into the fluorination kettle heated in the step 1) to perform dynamic fluorination reaction with the graphene for 0.5-2 h.
In a further preferred embodiment of the present invention, the pressure of the fluorination reaction mixture gas after thermal pre-dissociation introduced into the fluorination reactor during the static fluorination reaction is 50 to 120 Kpa.
As a further preferable technical scheme of the invention, during the dynamic fluorination reaction, the fluorination reaction mixed gas after thermal pre-dissociation is continuously introduced into the fluorination kettle at a flow rate of 0.5-5L/min.
According to another aspect of the invention, the invention further provides an application of fluorinated graphene, wherein the fluorinated graphene is applied to an insulating and heat conducting material as a single material or a composite material, and is prepared by the preparation method of the fluorinated graphene with high thermal stability, high insulation and high heat conductivity.
By adopting the technical scheme, the preparation method and the application of the fluorinated graphene with high thermal stability, insulation and heat conduction can achieve the following beneficial effects:
1) according to the preparation method of the fluorinated graphene with high thermal stability, high insulation and high heat conduction, provided by the invention, fluorine gas is introduced into a cache kettle at a certain temperature in advance for thermal pre-dissociation, so that the fluorine atoms with higher reaction activity and no reaction site tendency are dissociated into fluorine atoms, and the fluorine atoms and the graphene are subjected to a fluorination reaction by an atomic mechanism process, so that the fluorinated graphene prepared by the method has more uniform fluorine element distribution, the fluorinated graphene has a relatively uniform lattice structure, and the fluorinated graphene has excellent heat conduction performance;
2) according to the preparation method of the fluorinated graphene with high thermal stability, insulation and heat conduction, provided by the invention, as fluorine gas atoms subjected to thermal pre-dissociation have higher reactivity, the fluorination reaction can be carried out more quickly and sufficiently through thermal pre-dissociation fluorination, the reaction is more thorough, the time required by single fluorination is also quicker, and meanwhile, the fluorinated graphene with higher fluorine content can be prepared through relatively fewer fluorination times and fluorine gas consumption, so that the excellent insulation performance is further brought, the batch production is facilitated, and the production efficiency is high;
3) the fluorinated graphene prepared by the method has higher fluorine content, so that the carbon-fluorine bond in the product is mainly covalent bond, the thermal stability of the carbon-fluorine bond is effectively improved, the intrinsic thermal stability of the fluorinated graphene is further improved, the weight loss peak temperature of the fluorinated graphene reaches more than 570 ℃, and the temperature is improved by about 100 ℃ (Liu Xiang, Wang Xue, Gaojie, Huangjie Yang, Li Bao Ying and Vancuo compared with the prior related patents: CN103420352B, 2016-04-06.);
4) the fluorinated graphene prepared by the method disclosed by the invention has high thermal stability and excellent insulating and high heat-conducting properties, so that the fluorinated graphene and the composite material thereof can be effectively applied to the field of heat-conducting materials, such as the fluorinated graphene serving as an insulating and heat-conducting material in an electronic packaging layer to provide heat management capability.
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The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
FIG. 1 is a comparison of transmission electron microscope images of fluorinated graphene prepared by a pre-cracking fluorination process of the present invention (example 1) and fluorinated graphene prepared by a conventional temperature-rising fluorination process (comparative example 1);
FIG. 2 is a graph showing the energy gap curves of fluorinated graphene prepared by the pre-cracking fluorination process of the present invention (example 1) and fluorinated graphene prepared by the conventional temperature-rising fluorination process (comparative example 1);
FIG. 3 is a graph of thermogravimetric analysis of fluorinated graphene prepared by the pre-cracking fluorination process of the present invention (example 1) and fluorinated graphene prepared by the conventional temperature-rising fluorination process (comparative example 1) at 30-800 ℃ in a nitrogen atmosphere temperature-rising process, respectively.
The objects, features and advantages of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The invention will be further described with reference to the accompanying drawings and specific embodiments. In the preferred embodiments, the terms "upper", "lower", "left", "right", "middle" and "a" are used for clarity of description only, and are not used to limit the scope of the invention, and the relative relationship between the terms and the terms is not changed or modified substantially without changing the technical content of the invention.
The invention provides a high thermal stability, insulation and conductivityThe preparation method of the thermal fluorinated graphene, also called as a pre-cracking fluorination process, is to heat fluorine gas molecules before a fluorination reaction so as to thermally pre-dissociate the fluorine gas molecules into fluorine atoms, and then introduce the fluorine atoms into a fluorination reaction kettle to perform a fluorination reaction with graphene so as to prepare the fluorinated graphene which has more uniform fluorine element distribution, high thermal stability, high insulation and high thermal conductivity, and is also called as pre-dissociated fluorinated graphene. The fluorine-carbon atomic ratio of the fluorinated graphene is 0.5-0.7, the fluorine atom and the carbon atom are bonded in a covalent bond mode, and the thermal weight loss peak is greater than 570 ℃. Moreover, the graphene cellulose composite film with the mass fraction of fluorinated graphene being 40% prepared by the method has the square resistance being more than 1 x 10 measured by a four-probe method9Ω/sq, in-plane thermal conductivity greater than 13W/(m × K).
The invention provides a preparation method of fluorinated graphene with high thermal stability, high insulation and high heat conductivity, which comprises the following steps:
1) placing the dried graphene in a fluorination kettle, vacuumizing the fluorination kettle, introducing nitrogen and pumping out the fluorination kettle for multiple replacement treatments, and heating the fluorination kettle to 140-260 ℃; the replacement treatment is to replace the air in the fluorination kettle by vacuumizing, then introducing nitrogen and pumping out the nitrogen. The multiple substitution treatment is performed to enhance the substitution effect, and in a specific embodiment, the multiple substitution treatment may be performed 2 to 5 times.
2) Performing replacement treatment on the cache kettle for multiple times as same as that in the step 1), and then heating to the temperature as that of the fluorination kettle in the step 1); the substitution treatment method in this step is the same as that in step 1), and the number of substitution treatments is also 2 to 5, but the number of substitution treatments in step 1) and step 2) may be the same or different, and is not limited herein.
3) Introducing the fluorination reaction mixed gas into the heated buffer kettle in the step 2), keeping the temperature for 10-30min, and performing thermal pre-dissociation to convert part of fluorine gas molecules in the fluorination reaction mixed gas into fluorine atoms;
4) and (3) introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation in the step 3) into the fluorination kettle heated in the step 1), and carrying out fluorination reaction with the graphene for 0.5-2h to obtain the fluorinated graphene with high thermal stability, insulation and heat conductivity.
It should be noted that, there is no precedence relationship between the execution sequences of step 1) and step 2), and step 1) may be executed first, and then step 2 is executed, or step 2) may be executed first, and then step 1) is executed; in order to improve the execution efficiency, the execution may be performed simultaneously.
In order to make those skilled in the art further understand the technical solution of the present invention, the technical solution of the present invention is further described in detail by way of examples below.
Example 1
Placing graphene in a fluorination kettle, replacing air in the fluorination kettle and a cache kettle with nitrogen for three times, and then heating the fluorination kettle and the cache kettle to 140 ℃;
introducing a fluorination reaction mixed gas with fluorine gas concentration of 20% mixed by fluorine gas and nitrogen gas into the buffer kettle, and keeping for 10min for thermal pre-dissociation;
and (3) introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation into a fluorination kettle until the air pressure is 50Kpa, carrying out fluorination reaction for 1 hour, and taking out a sample after the fluorination kettle is naturally cooled to obtain the fluorinated graphene.
The samples of this example were tested: the fluorine-carbon atomic ratio of the fluorinated graphene is 0.61 in XPS test, the temperature of a thermal weight loss peak in TGA test is 576 ℃, the fluorinated graphene is applied to the cellulose composite film, the cellulose composite film with the mass fraction of the fluorinated graphene being 40% has the in-plane thermal conductivity of 12.9W/(m.multidot.K), the in-plane thermal conductivity of 11.1W/(m.multidot.K) when the mass fraction is 30%, and the in-plane thermal conductivity of 10.5W/(m.multidot.K) when the mass fraction is 20%.
Example 2
Placing graphene in a fluorination kettle, replacing air in the fluorination kettle and a cache kettle with nitrogen for three times, and then heating the fluorination kettle and the cache kettle to 200 ℃;
introducing a fluorination reaction mixed gas with fluorine gas concentration of 10% mixed by fluorine gas and nitrogen gas into the buffer kettle, and keeping for 10min for thermal pre-dissociation;
and (3) introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation into a fluorination kettle until the air pressure is 80Kpa, carrying out fluorination reaction for 1 hour, and taking out a sample after the fluorination kettle is naturally cooled to obtain the fluorinated graphene.
The samples of this example were tested: the fluorine-carbon atomic ratio of the fluorinated graphene is 0.55 in an XPS test, the temperature of a thermal weight loss peak in a TGA test is 565 ℃, the fluorinated graphene is applied to the cellulose composite film, and the in-plane thermal conductivity of the cellulose composite film with the mass fraction of the fluorinated graphene being 40% is 13.1W/(m × K).
Example 3
Placing graphene in a fluorination kettle, replacing air in the fluorination kettle and a cache kettle with nitrogen for three times, and then heating to 260 ℃;
introducing a fluorination reaction mixed gas with fluorine gas concentration of 20% mixed by fluorine gas and nitrogen gas into the buffer kettle, and keeping for 10min for thermal pre-dissociation;
and (3) introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation into a fluorination kettle until the air pressure is 100Kpa, carrying out fluorination reaction for 2 hours, and taking out a sample after the fluorination kettle is naturally cooled to obtain the fluorinated graphene.
The samples of this example were tested: the fluorine-carbon atomic ratio of the fluorinated graphene is 0.61 in XPS test, the temperature of a thermal weight loss peak in TGA test is 612 ℃, the fluorinated graphene is applied to the cellulose composite film, and the in-plane thermal conductivity of the cellulose composite film with the mass fraction of the fluorinated graphene being 40% is 13.3W/(m × K).
Example 4
Placing graphene in a fluorination kettle, replacing air in the fluorination kettle and a cache kettle with nitrogen for three times, and then heating to 200 ℃;
introducing a fluorination reaction mixed gas with fluorine gas concentration of 10% mixed by fluorine gas and nitrogen gas into the buffer kettle, and keeping for 20min for thermal pre-dissociation;
and (3) introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation into a fluorination kettle until the air pressure is 120Kpa, carrying out fluorination reaction for 1 hour, and taking out a sample after the fluorination kettle is naturally cooled to obtain the fluorinated graphene.
The samples of this example were tested: the fluorine-carbon atomic ratio of the fluorinated graphene is 0.60 through XPS test, the temperature of a thermal weight loss peak is 593 ℃ through TGA test, the fluorinated graphene is applied to the cellulose composite film, and the in-plane thermal conductivity of the cellulose composite film with the mass fraction of the fluorinated graphene being 40% is 12.6W/(m × K).
Example 5
Placing graphene in a fluorination kettle, replacing air in the fluorination kettle and a cache kettle with nitrogen for three times, and then heating to 200 ℃;
introducing a fluorination reaction mixed gas with fluorine gas concentration of 5% mixed by fluorine gas and nitrogen gas into the buffer kettle, and keeping for 30min for thermal pre-dissociation;
and (3) introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation into a fluorination kettle until the air pressure is 100KPa, carrying out fluorination reaction for 0.5 hour, and taking out a sample after the fluorination kettle is naturally cooled to obtain the fluorinated graphene.
The samples of this example were tested: the fluorine-carbon atomic ratio of the fluorinated graphene is 0.57 in XPS test, the thermal weight loss peak temperature is 581 ℃ in TGA test, and the in-plane thermal conductivity of the cellulose composite film with the mass fraction of the fluorinated graphene being 40% is 13.4W/(m × K).
Example 6
Placing graphene in a fluorination kettle, replacing air in the fluorination kettle and a cache kettle with nitrogen for three times, and then heating to 200 ℃;
introducing a fluorination reaction mixed gas with fluorine gas concentration of 10% mixed by fluorine gas, nitrogen gas and carbon dioxide into the buffer kettle, and keeping for 10min for thermal pre-dissociation;
and (3) introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation into a fluorination kettle until the air pressure is 100KPa, carrying out fluorination reaction for 1 hour, and taking out a sample after the fluorination kettle is naturally cooled to obtain the fluorinated graphene.
The samples of this example were tested: the fluorine-carbon atomic ratio of the fluorinated graphene is 0.59 through XPS test, the thermal weight loss peak temperature is 569 ℃ through TGA test, the fluorinated graphene is applied to the cellulose composite film, and the in-plane thermal conductivity of the cellulose composite film with the mass fraction of the fluorinated graphene being 40% is 11.8W/(m & ltx & gt K).
Example 7
Placing graphene in a fluorination kettle, vacuumizing, replacing air in the fluorination kettle and a cache kettle with nitrogen for three times, and then heating to 200 ℃;
introducing a fluorination reaction mixed gas with fluorine gas concentration of 10% mixed by fluorine gas and nitrogen gas into the buffer kettle, and keeping for 20min for thermal pre-dissociation;
and (3) introducing the mixed gas of the pre-dissociation reaction into a fluorination kettle at the flow rate of 0.5L/min, continuously pumping the gas out, carrying out the fluorination reaction for 1 hour, and taking out the sample after the fluorination kettle is naturally cooled to obtain the fluorinated graphene.
The samples of this example were tested: the fluorine-carbon atomic ratio of the fluorinated graphene is 0.65 in an XPS test, the temperature of a thermal weight loss peak in a TGA test is 604 ℃, the fluorinated graphene is applied to the cellulose composite film, and the in-plane thermal conductivity of the cellulose composite film with the mass fraction of the fluorinated graphene being 40% is 12.5W/(m × K).
Example 8
Placing graphene in a fluorination kettle, vacuumizing, replacing air in the fluorination kettle and a cache kettle with nitrogen for three times, and then heating to 200 ℃;
introducing a fluorination reaction mixed gas with fluorine gas concentration of 20% mixed by fluorine gas and nitrogen gas into the buffer kettle, and keeping for 30min for thermal pre-dissociation;
and (3) introducing the mixed gas of the pre-dissociation reaction into a fluorination kettle at the flow rate of 0.1L/min, continuously pumping the gas out, carrying out the fluorination reaction for 1 hour, and taking out the sample after the fluorination kettle is naturally cooled to obtain the fluorinated graphene.
The samples of this example were tested: the fluorine-carbon atomic ratio of the fluorinated graphene is 0.68 in XPS test, the thermal weight loss peak temperature is 611 ℃ in TGA test, the fluorinated graphene is applied to the cellulose composite film, and the in-plane thermal conductivity of the cellulose composite film with the mass fraction of the fluorinated graphene being 40% is 12.7W/(m x K).
The following comparative example adopts a traditional temperature-rising fluorination process, and the prepared fluorinated graphene can be called temperature-rising fluorinated graphene, and is mainly different from the method in that the fluorine gas is not subjected to thermal pre-dissociation treatment.
Comparative example 1
Placing graphene in a fluorination kettle, vacuumizing, replacing air in the fluorination kettle with nitrogen for three times, introducing fluorine and nitrogen mixed gas with the fluorine concentration of 20% into the fluorination kettle to 50Kpa, heating to 200 ℃, carrying out fluorination reaction for 1 hour, and taking out a sample after the fluorination kettle is naturally cooled to obtain the fluorinated graphene.
The samples of this comparative example were tested: the fluorine-carbon atomic ratio of the fluorinated graphene is 0.53 by XPS test, the peak temperature of thermal weight loss is 475 ℃ by TGA test, and the fluorinated graphene is applied to the cellulose composite film, wherein the in-plane thermal conductivity of the cellulose composite film with the mass fraction of the fluorinated graphene being 40% is 9.9W/(m.K), the in-plane thermal conductivity is 9.4W/(m.K) when the mass fraction is 30%, and the in-plane thermal conductivity is 8.9W/(m.K) when the mass fraction is 20%.
Comparative example 2
Placing graphene in a fluorination kettle, vacuumizing, replacing air in the fluorination kettle with nitrogen for three times, introducing a fluorine gas/nitrogen gas mixed gas with the fluorine gas concentration of 20% into the fluorination kettle to 80Kpa, heating to 200 ℃, carrying out fluorination reaction for 1 hour, and taking out a sample after the fluorination kettle is naturally cooled to obtain the fluorinated graphene.
The samples of this comparative example were tested: the fluorine-carbon atomic ratio of the fluorinated graphene is 0.63 in XPS test, the temperature of a thermal weight loss peak in TGA test is 510 ℃, the fluorinated graphene is applied to the cellulose composite film, and the in-plane thermal conductivity of the cellulose composite film with the mass fraction of the fluorinated graphene being 40% is 8.6W/(m & ltx & gt K).
Comparative example 3
Placing graphene in a fluorination kettle, vacuumizing, replacing air in the fluorination kettle with nitrogen for three times, introducing fluorine gas/nitrogen mixed gas with the fluorine gas concentration of 5% into the fluorination kettle to 100Kpa, heating to 140 ℃, carrying out fluorination reaction for 0.5 hour, and taking out a sample after the fluorination kettle is naturally cooled to obtain the fluorinated graphene.
The samples of this comparative example were tested: the fluorine-carbon atomic ratio of the fluorinated graphene is 0.47 in XPS test, the temperature of a thermal weight loss peak in TGA test is 431 ℃, the fluorinated graphene is applied to the cellulose composite film, and the in-plane thermal conductivity of the cellulose composite film with the mass fraction of the fluorinated graphene being 40% is 7.3W/(m × K).
Comparative example 4
Placing graphene in a fluorination kettle, vacuumizing, replacing air in the fluorination kettle with nitrogen for three times, introducing fluorine and nitrogen mixed gas with the fluorine concentration of 10% into the fluorination kettle to 120Kpa, heating to 260 ℃, carrying out fluorination reaction for 0.5 hour, and taking out a sample after the fluorination kettle is naturally cooled to obtain the fluorinated graphene.
The samples of this comparative example were tested: the fluorine-carbon atomic ratio of the fluorinated graphene is 0.51 in XPS test, the temperature of a thermal weight loss peak in TGA test is 449 ℃, the fluorinated graphene is applied to the cellulose composite film, and the in-plane thermal conductivity of the cellulose composite film with the mass fraction of the fluorinated graphene being 40% is 9.4W/(m × K).
Compared with the conventional temperature-rising fluorination process in the comparative examples 1 to 4, in which the temperature of the fluorination kettle is raised after the mixed gas of the fluorination reaction is directly introduced, the thermal pre-dissociation process of the fluorine gas is not performed, so that the fluorine gas reacts with the graphene in a molecular state, and a fluorination region grows according to a diffusion model, and uneven fluorine distribution is finally caused.
The fluorinated graphene prepared by the thermal pre-dissociation fluorination process provided by the embodiment 1 of the invention and the fluorinated graphene prepared by the temperature-rising fluorination process provided by the comparative example 1 are respectively compared under a transmission electron microscope image, and then fluorine and carbon elements on the fluorinated graphene sheet layer are respectively calculated and divided by using point density analysis software to obtain a series of effective values and variances of the effective values, as shown in fig. 1, the smaller the variance of each effective value is, which indicates that the more uniform the distribution of the fluorine elements on the graphene sheet layer is. The calculation result shows that the variance of each effective value on the thermal pre-dissociation fluorinated graphene is 0.011 and less than 0.026 of the temperature-rising fluorinated graphene, and further shows that the fluorine element on the fluorinated graphene prepared by the thermal pre-dissociation fluorination is more uniformly distributed. The graphene fluoride has more uniform fluorine distribution, which leads to more complete damage to the conjugated structure and higher energy gap, and as shown in fig. 2, the energy gap of the thermal pre-dissociation graphene fluoride is 4.36eV, which is greater than the energy gap of the temperature-rising graphene fluoride by 3.75eV, which indicates that the graphene fluoride prepared by the thermal pre-dissociation fluorination process has better insulation property. As shown in fig. 3, by comparing the thermogravimetric analysis images of the products of example 1 and comparative example 1 in the process of raising the temperature in the nitrogen atmosphere at 30-800 ℃, it can be seen that the thermal decomposition starting temperature and the maximum weight loss peak temperature of the thermal pre-dissociated graphene fluoride are both improved by 60-100 ℃ compared with the temperature-raised graphene fluoride, which indicates that the more uniform fluorine distribution structure also brings higher thermal stability and thermal conductivity to the products.
The process parameters of examples 1-8 and comparative examples 1-4 and the test data of the samples produced are shown in tables 1 and 2.
TABLE 1 Process parameters and test data for samples made in examples 1-8
TABLE 2 Process parameters and test data for samples produced in comparative examples 1-4
Analysis table 1 shows that in example 3, the thermal pre-dissociation of the mixed gas of 20% fluorine gas by keeping the mixed gas at 260 ℃ for 10min contributes to the maximum improvement of the thermal stability and thermal conductivity of the fluorinated graphene. According to the Arrhenius formula, the reaction rate can be increased by 2-4 times for every 10K increase of the temperature. The reaction temperature is increased, so that the fluorine gas cracking rate is greatly increased, and the concentration of fluorine atoms in the mixed gas is further increased, so that the thermal pre-dissociation process is more sufficient.
The comparative analysis of tables 1 and 2 shows that the performance of fluorinated graphene is effectively improved after the thermal pre-dissociation process of the fluorinated mixed gas is added before the direct temperature-rising fluorination process. The temperature of the thermal weight loss peak is increased by 100-150 ℃, and the in-plane thermal conductivity of 40 percent of the cellulose composite film is increased by 20-40 percent.
The fluorinated graphene prepared by the method has high fluorine content, so that carbon-fluorine bonds in a product are mainly covalent bonds, the thermal stability of the carbon-fluorine bonds is effectively improved, the intrinsic thermal stability of the fluorinated graphene is further improved, and the data in tables 1 and 2 show that the weight loss peak temperature of the fluorinated graphene reaches more than 570 ℃ and is improved by about 100 ℃ compared with the traditional technology. Therefore, the fluorinated graphene prepared by the method has higher thermal stability and better insulating and high heat-conducting properties, so that the fluorinated graphene and the composite material thereof can be better applied to the field of heat-conducting materials.
The fluorination process can flexibly select dynamic fluorination or static fluorination according to actual production requirements, so that the fluorination process has lower requirements on equipment and meets the requirements of large-scale production.
Although specific embodiments of the present invention have been described above, it will be appreciated by those skilled in the art that these are merely examples and that many variations or modifications may be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims.
Claims (10)
1. A preparation method of fluorinated graphene with high thermal stability, insulation and heat conduction is characterized by comprising the following steps:
1) placing the dried graphene in a fluorination kettle, vacuumizing the fluorination kettle, introducing nitrogen and pumping out the nitrogen to perform multiple replacement treatments, and heating the fluorination kettle to 140-260 ℃;
2) performing replacement treatment on the cache kettle for multiple times as same as that in the step 1), and then heating to the temperature as that of the fluorination kettle in the step 1);
3) introducing the fluorination reaction mixed gas into the heated buffer kettle in the step 2), and keeping for 10-30min for thermal pre-dissociation to convert part of fluorine gas molecules in the fluorination reaction mixed gas into fluorine atoms;
4) and (3) introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation in the step 3) into the fluorination kettle heated in the step 1), and carrying out fluorination reaction with the graphene for 0.5-2h to obtain the fluorinated graphene with high thermal stability, insulation and heat conductivity.
2. The preparation method of fluorinated graphene with high thermal stability, insulation and thermal conductivity as claimed in claim 1, wherein step 1) is preceded by the following steps: and putting the raw material of the graphene into a vacuum oven, heating to 100 ℃, and carrying out vacuum treatment for 5-10h to obtain the dried graphene.
3. The method for preparing fluorinated graphene with high thermal stability, insulation and heat conduction according to claim 1, wherein the graphene is single-layer graphene, few-layer graphene, graphene oxide, reduced graphene oxide, nitrogen-doped graphene or porous graphene, or is graphene aerogel, graphene fiber or graphene film.
4. The method for preparing fluorinated graphene with high thermal stability, insulation and thermal conductivity as claimed in claim 1, wherein the mixed gas of the fluorination reaction is a mixed gas of fluorine gas and inert gas, or a mixed gas of fluorine gas, inert gas and oxygen gas.
5. The method of claim 4, wherein the inert gas is at least one of helium, neon, argon, krypton, xenon, nitrogen, and carbon dioxide.
6. The method for preparing fluorinated graphene with high thermal stability, insulation and heat conductivity as claimed in claim 5, wherein the concentration of fluorine gas in the mixed gas of the fluorination reaction is 5-20 v/v%.
7. The preparation method of fluorinated graphene with high thermal stability, insulation and thermal conductivity according to claim 1, wherein the step 4) specifically comprises:
introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation in the step 3) into the fluorination kettle heated in the step 1) for one time or multiple times, and performing static fluorination reaction with graphene for 0.5-2 h; or continuously introducing the fluorination reaction mixed gas subjected to thermal pre-dissociation in the step 3) into the fluorination kettle heated in the step 1) to perform dynamic fluorination reaction with the graphene for 0.5-2 h.
8. The method according to claim 7, wherein the pressure of the fluorination reaction mixture gas introduced into the fluorination reactor after thermal pre-dissociation is 50 to 120Kpa during the static fluorination reaction.
9. The method for preparing fluorinated graphene with high thermal stability, insulation and heat conductivity as claimed in claim 7, wherein during the dynamic fluorination reaction, the mixed gas of the fluorination reaction after thermal pre-dissociation is continuously introduced into the fluorination kettle at a flow rate of 0.5-5L/min.
10. The application of the fluorinated graphene is characterized in that the fluorinated graphene is applied to an insulating and heat conducting material as a single material or a composite material, and the fluorinated graphene is prepared by the preparation method of the fluorinated graphene with high thermal stability, insulation and high heat conductivity as claimed in any one of claims 1 to 9.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114975906A (en) * | 2022-07-27 | 2022-08-30 | 湘潭大学 | Preparation method of nitrogen-doped fluorinated modified graphene negative electrode material and battery |
| CN115160733A (en) * | 2022-07-19 | 2022-10-11 | 安徽宇航派蒙健康科技股份有限公司 | Epoxy resin composite material, preparation method thereof, heat conducting fin and electronic device |
| CN115231565A (en) * | 2022-06-29 | 2022-10-25 | 安徽宇航派蒙健康科技股份有限公司 | Fluorinated graphene heat-conducting film and preparation method thereof |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104211048A (en) * | 2013-06-05 | 2014-12-17 | 中国科学院上海有机化学研究所 | Preparation method of fluorinated graphene |
| CN106672939A (en) * | 2016-12-05 | 2017-05-17 | 四川大学 | Fluorinated graphene with large surface area and high thermal stability and preparation method thereof |
| CN108516542A (en) * | 2018-06-27 | 2018-09-11 | 叶荣森 | A kind of preparation method of high fluorinated volume nanometer fluorinated graphene |
| JP2019077595A (en) * | 2017-10-25 | 2019-05-23 | 株式会社豊田中央研究所 | Fluorographene and production method of the same, composite material, lithium secondary battery, optical component, electronics component and gas barrier film |
-
2022
- 2022-03-24 CN CN202210299829.0A patent/CN114436251B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104211048A (en) * | 2013-06-05 | 2014-12-17 | 中国科学院上海有机化学研究所 | Preparation method of fluorinated graphene |
| CN106672939A (en) * | 2016-12-05 | 2017-05-17 | 四川大学 | Fluorinated graphene with large surface area and high thermal stability and preparation method thereof |
| JP2019077595A (en) * | 2017-10-25 | 2019-05-23 | 株式会社豊田中央研究所 | Fluorographene and production method of the same, composite material, lithium secondary battery, optical component, electronics component and gas barrier film |
| CN108516542A (en) * | 2018-06-27 | 2018-09-11 | 叶荣森 | A kind of preparation method of high fluorinated volume nanometer fluorinated graphene |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115231565A (en) * | 2022-06-29 | 2022-10-25 | 安徽宇航派蒙健康科技股份有限公司 | Fluorinated graphene heat-conducting film and preparation method thereof |
| CN115160733A (en) * | 2022-07-19 | 2022-10-11 | 安徽宇航派蒙健康科技股份有限公司 | Epoxy resin composite material, preparation method thereof, heat conducting fin and electronic device |
| CN114975906A (en) * | 2022-07-27 | 2022-08-30 | 湘潭大学 | Preparation method of nitrogen-doped fluorinated modified graphene negative electrode material and battery |
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