CN107098338B - Graphene material, preparation method thereof and sagger for preparing graphene - Google Patents
Graphene material, preparation method thereof and sagger for preparing graphene Download PDFInfo
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- CN107098338B CN107098338B CN201710425378.XA CN201710425378A CN107098338B CN 107098338 B CN107098338 B CN 107098338B CN 201710425378 A CN201710425378 A CN 201710425378A CN 107098338 B CN107098338 B CN 107098338B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2204/00—Structure or properties of graphene
- C01B2204/20—Graphene characterized by its properties
- C01B2204/22—Electronic properties
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2204/00—Structure or properties of graphene
- C01B2204/20—Graphene characterized by its properties
- C01B2204/30—Purity
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
- C01P2002/82—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by IR- or Raman-data
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention relates to a sagger for preparing graphene, the sagger is made of high-density graphite, the sagger comprises a sagger main body and a box cover, the top of the sagger main body is provided with an opening, the box cover covers the top of the sagger main body, wherein the sagger main body comprises an outer sagger wall body and an outer cavity formed by the outer sagger wall body, and the outer sagger wall body is provided with a notch so that the outer cavity is communicated with the outside; the sagger body is also provided with an inner box, the inner box comprises an inner box wall body and an inner cavity formed by the inner box wall body, and the inner cavity is communicated with the outer cavity. The invention also provides a method for preparing the graphene material by using the device and the graphene material.
Description
Technical Field
The invention relates to a graphene material, in particular to a sagger for preparing graphene, a graphene material and a preparation method of the graphene material.
Background
Due to the development of new energy technologies, particularly electric automobile technologies, great demands are put on high-capacity high-power-density high-performance power batteries and the like. Graphene is considered as one of key materials of a conductive agent for a high-performance power battery as a high-conductivity two-dimensional nanomaterial.
The existing preparation methods of the graphene are a chemical oxidation-reduction method, a mechanical stripping method, a CVD (chemical vapor deposition) method and the like. However, the graphene produced by these methods has drawbacks. For example, by adopting a chemical oxidation-reduction method, although the graphene has smaller thickness and high single-layer rate, the graphene is greatly damaged in the oxidation process, holes are generated, other functional groups, a large amount of sulfur elements, iron, cobalt, nickel, manganese and other metal impurities are introduced, the conductivity of the graphene is greatly influenced, and the performance of the battery is damaged when the graphene is applied to the battery in the follow-up process. By adopting a mechanical stripping method, the graphene has the defects of thicker thickness and more layers although the graphene has high conductivity, and the method has the biggest problems that: when the adopted raw materials are flake graphite, expandable graphite or expanded worm graphite and are physically and mechanically stripped by a liquid phase or gas phase method, the raw materials contain a large amount of sulfur elements and residual impurities such as Fe-Co-Ni-Mn-K-Ca and the like, and the content of the impurities is greatly out of standard, so that the performance of the battery can be damaged. By adopting the CVD vapor deposition method, the obtained graphene has the characteristics of thinner single-layer or double-layer thickness and extremely high conductivity, but the substrate with a large amount of metallic nickel and the like is required to be used, and the substrate is required to be dissolved and peeled, so that the yield of the graphene is extremely low and cannot be used for large-scale ton-level application.
Disclosure of Invention
In view of the above, it is necessary to provide a sagger, a preparation method, and a graphene material having excellent conductivity, which can be used for mass production of a graphene material having excellent conductivity.
The invention provides a sagger for preparing graphene, which comprises a sagger main body and a box cover, wherein the top of the sagger main body is provided with an opening, the box cover is covered on the top of the sagger main body,
the sagger main body comprises an outer sagger wall body and an outer cavity formed by the outer sagger wall body, wherein the outer sagger wall body is provided with a notch so that the outer cavity is communicated with the outside;
the sagger main body is also provided with an inner box, the inner box comprises an inner box wall body and an inner cavity formed by the inner box wall body, the top of the inner box is provided with an opening, and the inner cavity is communicated with the outer cavity;
the box cover comprises a box cover top and a box cover wall body, wherein the box cover wall body is arranged in the outer cavity of the box body, and the height of the box cover wall body is smaller than that of the outer box wall body.
Preferably, the inner box wall body is composed of a pair of first baffles and a pair of second baffles, and the height of the first baffles is larger than that of the second baffles.
Preferably, the top of the box cover is composed of a top plate and a first concave part, the first concave part is formed around the top plate, and the minimum size of the first concave part on the surface of the top plate in any direction is larger than the thickness of the outer box wall body of the box body.
Preferably, at least one second recess is provided in the first recess, and the length of the second recess in the x direction is greater than the thickness of the outer casing wall of the casing body.
Preferably, the material of the sagger is high-density graphite, and the high-density graphite is a graphite raw materialThe density of the high-density graphite is more than or equal to 1.85g/cm 3 。
Preferably, the high temperature treatment of the graphite raw material specifically means a pressure treatment of applying 1 to 3.6 atmospheres to the graphite raw material at a temperature of 2400 to 3000 ℃.
The invention also provides a method for preparing the graphene material by using the sagger, which comprises the following steps:
(1) Providing a graphite raw material;
(2) Oxidizing a graphite raw material, and then placing oxidized graphite in a sagger, and reducing the graphite in an inert atmosphere at 1000-1400 ℃ to obtain a graphene material, wherein the sagger is made of high-density graphite.
Preferably, the time of the reduction in step (2) is 20 minutes to 20 hours.
Preferably, the temperature of the reduction in the step (2) is 1000 ℃ to 1100 ℃, and the time of the reduction is 30 minutes to 12 hours.
The invention also provides a graphene material prepared by the method, and the conductivity of the graphene material is 10 5 And S/m or more, wherein the graphene material has a basically defect-free structure.
Compared with the prior art, the material of the sagger for preparing the graphene is high-density graphite, so that the sagger has the advantage of high temperature resistance.
The notch of the outer box wall body has the function of enabling the outer cavity to be communicated with the outside, and impurity gases such as water and sulfur dioxide generated in the raw materials can be discharged to the outside in the process of preparing the graphene material. The inner space of the sagger main body is divided into three mutually communicated subspaces (an inner cavity, a first outer subchamber and a second outer subchamber) by the inner box and the box cover wall body. The special complex labyrinth structure is formed by the design of the notch of the outer box wall body, the inner box, the box cover wall body and the outer box wall body, so that a longer and winding gas channel is formed. When graphite oxide is placed in the inner cavity of the inner box, under the action of high temperature, powdery graphite oxide is subjected to explosive stripping reduction to obtain graphene materials, the graphene materials flow together with an airflow type mixture formed by gases such as sulfur dioxide, and when the inner box wall body (namely the first baffle and the second baffle) with a blocking effect, the box cover wall body and the outer box wall body are encountered, the airflow type mixture collides with the inner box wall body, so that the gases such as sulfur dioxide are discharged, the graphene powder is deposited, and the yield of the graphene materials is greatly improved.
The sagger has the advantages of simple structure, simple preparation method, easily available raw materials and low cost, and is suitable for large-scale industrialized application.
When the graphene oxide material is used, graphite oxide is placed in the sagger, and then the graphite oxide is reduced at a high temperature to obtain the graphene material. Compared with the preparation container or substrate used in the existing method, the sagger is made of high-density graphite, so that other extra impurities are prevented from being introduced, meanwhile, the sagger is used as a preparation space place, and the step of stripping the substrate by a CVD method is not needed in the follow-up process, so that the preparation of the graphene material is greatly facilitated.
In the existing graphene preparation process by adopting an oxidation-reduction method, hydrazine hydrate is adopted for reduction, so that the obtained graphene has more defects and has more impurity content; in the application, graphite oxide is placed in a sagger made of the high-density graphite material, and the sagger is placed in a high-temperature environment, so that the graphite oxide can be graphitized at a high temperature to obtain the graphene material. The preparation method has the advantages of extremely convenient raw material input and product collection, high yield, realization of large-scale preparation, and realization of hundred-ton-level preparation in practical application. In addition, other raw materials are not needed to be added in the preparation process, so that other impurities are not introduced; no peeling is required because the substrate or the like is not used. The whole preparation process has simple steps and high preparation efficiency.
The graphene material obtained by the preparation method has the following advantages: the graphene material can be obtained by only carrying out high-temperature reduction treatment on the graphite oxide, and is basically defect-free, thinner in thickness, extremely low in metal impurity content and high in conductivity. The obtained graphene material can be applied to conductive paste and further used for preparing batteries.
Drawings
FIG. 1 is a schematic view of the structure of the sagger of the present invention.
FIG. 2 is an exploded view of the sagger of FIG. 1.
Fig. 3 is a schematic view of the structure of the sagger body of the sagger of fig. 1.
Fig. 4 is a schematic structural view of a lid of the sagger of fig. 1.
Fig. 5 is a Transmission Electron Microscope (TEM) photograph of the graphene material obtained in example (1) of the present invention.
Fig. 6 is a TEM photograph of the graphene material obtained in comparative example (1).
Fig. 7 is a raman spectrum of a graphene material obtained in example (1) of the present invention.
Fig. 8 is a raman spectrum of the graphene material obtained in comparative example (1).
Fig. 9 is an X-ray diffraction (XRD) pattern of the graphene material obtained in example (1) of the present invention.
Fig. 10 is an XRD pattern of the graphene material obtained in comparative example (1).
Wherein 10 denotes a box cover, 10a denotes a box cover top, and 10a1 denotes a top plate; 10a2 denotes a first recess, 10a3 denotes a second recess, 10b denotes a lid wall, 20 denotes a sagger body, 20a denotes an outer sagger wall, 20b denotes a notch, 20c denotes an outer cavity, 30 denotes an inner sagger, 30a denotes an inner cavity, 30b denotes a first baffle, and 30c denotes a second baffle.
The invention will be further illustrated by the following specific examples in conjunction with the above-described figures.
Detailed Description
The sagger for preparing graphene, the graphene material and the preparation method thereof provided by the invention are further described below with reference to the accompanying drawings.
The invention provides a sagger for preparing graphene. Referring to fig. 1 to 4, the sagger includes a sagger cover 10 and a sagger body 20. The top of the sagger main body 20 is an opening, and the sagger cover 10 covers the top of the sagger main body 20. The sagger main body 20 and the box cover 10 are independent from each other, and the box cover 10 is not tightly fixed to the sagger main body 20, i.e. the sagger main body 20 and the box cover are not combined into a whole. The cartridge cover 10 is used while covering only the top of the sagger body 20. This is because, in the preparation process of graphene, powder materials such as graphite raw materials in the sagger are basically contained in the sagger due to the specific design of the sagger, and a large amount of powder materials cannot fly to the outside, and only a small amount of powder materials can escape, so that the powder materials can be ignored. Thus, the cartridge cover 10 does not need to be fixed to the cartridge body 20, which also reduces the complexity of the preparation of the cartridge and makes the use of the cartridge simpler.
Referring to fig. 3, the sagger body 20 includes an outer sagger wall 20a and an outer cavity 20c formed by the outer sagger wall 20 a. The outer casing wall 20a is provided with a notch 20b, so that the outer cavity 20c is communicated with the outside. When the graphite oxide powder is placed in the sagger body 20 for high temperature reduction, the generated water, sulfur dioxide, etc. escape through the notch 20b on the outer sagger wall 20 a. The reduced graphene collides with the inner box wall body and the outer box wall body 20a to fall down and deposit while the water, sulfur dioxide and the like escape, so that the yield of the graphene is improved. The shape of the sagger body 20 is not limited as long as there is an outer cavity 20c. The outer casing wall 20a has a plate-like structure, and may be a planar plate or a curved plate. The size and shape of the notch 20b are not limited, as long as the outer cavity 20c can be communicated with the outside.
An inner box 30 is also provided in the sagger body 20. The inner box 30 is integrally formed with the sagger body 20. The inner case 30 includes an inner case wall and an inner cavity 30a formed by the inner case wall. The top of the inner box 30 is an opening. The inner cavity 30a communicates with the outer cavity 20c. The shape of the inner box 30 may or may not be the same as the shape of the sagger body 20. The inner case 30 may be cylindrical, cubic, etc. in shape. The inner box wall body can be of a planar plate structure or a curved plate structure.
When the inner box wall is a planar plate structure, referring to fig. 2 and 3, the box body 20 and the inner box 30 are both rectangular, and theThe inner cartridge wall may be comprised of a pair of first baffles 30b and a pair of second baffles 30 c. The dimensions of the first baffle 30b and the second baffle 30c in the z-direction (i.e., the vertical direction) are defined as the height H of the first baffle 30b, respectively 3 Height H of the second baffle 30c 4 At this time H 3 ≥H 4 . In the preparation process, graphene powder is obtained after the graphite oxide powder is subjected to explosive stripping reduction, the graphene powder flows together with an airflow type mixture formed by gases such as sulfur dioxide, and when the inner box wall body, the box cover wall body and the outer box wall body which have a blocking effect are encountered, the airflow type mixture collides with the inner box wall body, the box cover wall body and the outer box wall body, so that the gases such as sulfur dioxide are discharged, and the graphene powder is deposited. In order to increase the probability and number of collisions of the air-flow mixture, it is preferable that the height of the first baffle 30b and the height of the second baffle 30c have a height difference, H 3 ＞H 4 。
When the inner box wall is a curved plate structure, an inner box notch (not shown) may be formed on the inner box wall.
In the above design, the height difference between the inner pocket gap or the first baffle 30b and the second baffle 30c is in order to facilitate adding more obstruction between the inner cavity 30a and the outer cavity 20c, so that the probability and the times of collision between the gas flow mixture formed by the graphene powder and the gas such as sulfur dioxide and the like and the inner pocket wall and the outer pocket wall with barrier effect collide to deposit, and the graphene powder is prevented from leaving the sagger along with the gas flow, thereby improving the yield of the final graphene powder. In other words, the sagger is designed to be complicated, so as to increase the channel length of gas circulation, change the discharge direction of the gas flow, improve the collision probability of the mixed gas flow formed by the graphene powder and the gas such as sulfur dioxide, the inner box wall body, the box cover wall body and the outer box wall body, change the flow direction of the graphene powder in the gas flow, cause more graphene powder to sink and deposit, and improve the yield of the graphene powder.
The cartridge cover 10 includes a cartridge cover top 10a and a cartridge cover wall 10b. The cartridge cover wall 10b is disposed within the outer cavity 20c of the sagger body 20. Defining the box cover wallThe dimensions of the body 10b and the outer casing wall 20a in the vertical z direction are respectively the height H of the casing cover wall 10b 1 Height H of outer cartridge wall 20a 2 . Height H of the box cover wall 10b 1 Less than the height H of the outer cartridge wall 20a 2 The purpose of this design is that when the lid 10 is put on top of the sagger body 20, the lid wall 10b extends into the outer cavity 20c of the sagger body 20, and divides the outer cavity 20c into a first sub-outer cavity 20c1 and a second sub-outer cavity 20c2 that are communicated with each other. In this specific design, the inner space of the sagger body 20 is divided into three mutually communicated subspaces (an inner cavity 30a, a first outer subchamber 20c1 and a second outer subchamber 20c 2) by the inner sagger 30 and the box cover wall body 10b, so that when graphite oxide is placed in the sagger body 20, graphene powder formed by reducing powdery graphite oxide under the action of high temperature is deposited by repeated collision of the inner sagger wall body (namely, the first baffle 30b and the second baffle 30 c), the box cover wall body 10b and the outer sagger wall body 20a, and a graphene material with a small number of layers is obtained.
Referring to fig. 2 and 4, the lid 10 includes an integral lid top 10a and lid wall 10b. The shape and size of the cartridge cover 10 are not limited. The dimensions of the cap top 10a in the x-axis and y-axis directions are defined as the length and width of the cap top 10 a. The box cover wall body 10b is arranged at a position close to the middle of the box cover top 10 a. Specifically, referring to fig. 4, the box top 10a is composed of a top plate 10a1 and a first recess 10a 2. The first concave portion 10a2 is formed around the top plate 10a1, that is, around the edge of the top plate 10a1 is concave inwards to form the first concave portion 10a2, that is, the thickness around the edge of the top plate 10a1 is thinner than the thickness of the middle portion of the top plate 10a1, so that the lid 10 is relatively stably located on the sagger main body 20, and excessive movement does not occur. Preferably, the smallest dimension of the first recess 10a2 in either direction on the surface of the top plate 10a1 is greater than the thickness of the outer box wall 20a of the box body 20. When the lid 10 is rectangular, the minimum dimensions of the first recess 10a2 in the x-direction and the y-direction are larger than the thickness D of the outer casing wall 20a of the casing body 20 2 . The preferred design is aimed at that when graphite oxide is placed in the outer cavity 20c, the top plate 10a1 of the top 10a of the lid cover partially extends into the outer cavity 20c, so that the area of the notch 20b is reduced as much as possible, and further, the powder graphite oxide is limited in the outer cavity 20c while the outer cavity 20c is ensured to be communicated with the outside, and more collision occurs between the powder graphite oxide.
Optionally, referring to fig. 2 and 4, at least one second recess 10a3 may be provided in the first recess 10a 2. The dimension D of the second recess 10a3 in the thickness direction of the outer casing wall 20a 1 Greater than the thickness D of the outer cartridge wall 20a of the cartridge body 20 2 . Specifically, when the sagger body 20 is a rectangular parallelepiped, the second concave portion 10a3 has a length D in the x-direction 1 Greater than the thickness D of the outer cartridge wall 20a of the cartridge body 20 2 . The second recess 10a3 serves as an additional passage for the external cavity 20c to communicate with the outside, thereby facilitating the discharge of small molecular water, carbon dioxide, etc.
In this embodiment, the sagger main body 20 and the inner box 30 are both rectangular parallelepiped, the height of the first baffle 30b of the inner box 30 is greater than the height of the second baffle 30c, and a pair of second recesses 10a3 are provided in the first recess 10a2 of the box cover 10.
The sagger is made of high-density graphite. The high-density graphite is graphite obtained by treating a graphite raw material at high temperature and high pressure. Specifically, the high-density graphite can be obtained by subjecting a graphite raw material to a pressure treatment of 1 to 3.6 atmospheres at a temperature of 2400 to 3000 ℃. Preferably, the high density graphite is obtained by subjecting a graphite raw material to a pressure treatment of 3.6 atmospheres at a temperature of 2500 to 2800 ℃. The graphite raw material is commercially available and will not be described in detail herein. It will be appreciated that after subjecting the graphite raw material to high temperature and high pressure, a milling step is also performed to obtain a sagger having a specific shape.
The sagger is made of high-density graphite, so that the sagger can resist high temperature, and is made of carbon elements which are the same as elements contained in the graphene material, so that no extra impurities are brought. Aiming at the defect that dust is easy to fly and difficult to fix caused by small density of a powdery graphite raw material when the existing graphene material is prepared, the sagger is specially applied to the preparation of the graphene material, and can conveniently contain the raw material and prepare the graphene material on a large scale. The device has simple structure, easy preparation and lower cost, and is beneficial to industrialized application.
The invention also provides a method for preparing the graphene material by using the sagger. The method comprises the following steps:
s1, providing a graphite raw material;
s2, oxidizing a graphite raw material, and then placing oxidized graphite in a sagger, and reducing the graphite in an inert atmosphere at the temperature of 1000-1400 ℃, wherein the sagger is made of high-density graphite.
In step S1, the graphite raw material may be graphite ore obtained by direct mining, or may be powdery material obtained by further purifying and/or pulverizing the graphite ore. The purification and/or comminution of graphite ore is known in the art and is not described in detail herein.
In the oxidation method in step S2, concentrated sulfuric acid is used as an intercalating agent (intercalation is performed on graphite), sodium nitrate is used as an intercalating agent auxiliary agent (sodium nitrate has strong oxidizing property in the presence of sulfuric acid), and potassium permanganate is used as a strong oxidizing agent to oxidize graphite into graphite oxide. And then, adding hydrogen peroxide to remove excessive potassium permanganate, and removing sodium ions and sulfate ions by hydrochloric acid to obtain purer graphite oxide.
The mechanism by which the graphite oxide is reduced is as follows: under inert atmosphere, the oxygen-containing group chemical bond on the surface of the graphite oxide is broken under high temperature by the high temperature environment to form micromolecular water and carbon dioxide which escape, and meanwhile, the interlayer spacing between the lamellar layers in the graphite oxide is enlarged by a large amount of escaped micromolecules; namely, the graphite oxide with a large number of layers is automatically exfoliated into graphene materials with a small number of layers at the same time of high-temperature reduction. The graphene material refers to graphene with the number of layers of 1-5. The inert atmosphere refers to inert gases such as nitrogen, argon, helium, neon and the like.
The temperature of the reduction is preferably 1000-1100 ℃. The time for the reduction is 20 minutes to 20 hours, preferably 30 minutes to 12 hours.
The high-temperature reduction and automatic stripping steps are realized through a sagger with a special structure. The material of the sagger is the same as that of the device for preparing the graphene material. This also allows for high temperature processing requirements, and does not introduce additional impurities into the reaction, as well as facilitating the removal of items from the sagger.
After step S2, a mechanical stripping step may be further included. The mechanical stripping can be a solid phase or liquid phase stripping method. Specifically, the graphene material obtained in the step S2 is mixed with a solvent such as water, N-methylpyrrolidone, a surfactant, etc., and mechanically peeled one or more times to obtain a graphene material with fewer layers. After the graphene material is mechanically stripped, the number of layers is fewer, and the conductivity is more excellent.
The graphene material can be used as a conductive agent directly or mixed with a solvent to form a conductive paste for further application.
The invention also provides the graphene material obtained by the preparation method. The graphene material is basically defect-free, thinner in thickness, higher in monolayer rate, extremely low in metal impurity content and high in conductivity. The conductivity of the graphene material is 10 5 S/m or more.
Hereinafter, the present invention will be further described with reference to specific examples.
Example (1)
(1) Providing a graphite raw material, wherein the graphite raw material is obtained by purifying and crushing graphite ores;
(2) Oxidizing a graphite raw material, placing oxidized graphite in a sagger, and reducing the graphite in an inert atmosphere at 1000-1050 ℃ to obtain the graphene material, wherein the sagger is made of high-density graphite.
Comparative example (1)
In order to better illustrate the advantages of the graphene materials obtained by the methods described herein, a comparison of example (1) is also provided. The comparative example (1) provides a preparation method of a graphene material.
The method comprises the following steps: the crushed and purified graphite raw material GC325 (325 meshes) is treated by concentrated sulfuric acid, sodium nitrate, potassium permanganate and the like by using a Hummers method to obtain graphite oxide powder; then the graphite oxide powder is put into a common chemical vapor deposition tube furnace for stripping, and the graphene powder is obtained
Transmission electron microscopy was performed on the graphene powder obtained in example (1), and the test results are shown in fig. 5.
The graphene powder obtained in comparative example (1) was subjected to transmission electron microscopy, and the test result is shown in fig. 6.
As can be seen from fig. 5 and 6, the graphene powder of example (1) showed a significant diffraction fringe in fig. 5, compared with that of comparative example (1), which indicates that the graphene powder of example (1) has a better crystallinity.
Raman spectrum test was performed on the graphene powder obtained in example (1), and the test result is shown in fig. 7.
Raman spectrum test was performed on the graphene powder obtained in comparative example (1), and the test result is shown in fig. 8.
As can be seen from FIGS. 7 to 8, example (1) was carried out at 1350cm -1 The position shows weaker characteristic peaks; and the strength of example (1) was much weaker than that of comparative example (1). In example (1), 1580cm -1 And 1350cm -1 Intensity ratio I of two characteristic peaks of (2) G /I d The ratio is larger than the ratio of the peak intensities of the two positions in the comparative example (1), which shows that the original structural defect of the graphene material is repaired after high-temperature graphitization treatment.
XRD test was performed on the graphene powder obtained in example (1), and the test results are shown in FIG. 9.
XRD test was performed on the graphene powder obtained in comparative example (1), and the test result is shown in FIG. 10.
As can be seen from fig. 9 and 10, the graphene powder obtained in comparative example (1) has a wider characteristic peak at a2θ angle of 22 ° to 26 ° (a interplanar spacing of more than 0.35nm is calculated from the correspondence of the characteristic peak) compared with example (1), which indicates that the interlayer spacing of the graphene prepared in comparative example (1) is larger. As can be seen from fig. 10, example (1) showed a sharp characteristic peak at a position where the 2θ angle was 26 ° (the interplanar spacing was calculated to be 0.345nm from the characteristic peak correspondence); and the half-peak width d of the characteristic peak is 0.34nm, which is basically close to the theoretical thickness of 0.34nm of the single-layer graphene. This also illustrates that graphene in the graphene powder of example (1) of the present application has a tendency to graphitize, and the interlayer spacing thereof is reduced. This is due to the rearrangement of carbon atoms during graphene repair to form single-layer graphene, and the strong interaction between two adjacent single-layer graphene layers, in turn, can cause recombination thereof to tend to form thicker two or more layers of graphene.
The graphene powder obtained in example (1) was subjected to a specific surface area test. The specific surface area of the graphene powder is 350g/cm 2 This further demonstrates that the graphene powder contains more graphene, and is suitable for further applications.
Further, the graphene material obtained in example (1) was subjected to a test for impurity content, and the results are shown in table 1.
TABLE 1
| Impurity element | Al | As | Ca | Cd | Co | Cr |
| Content (ppm) | 0.001 | 0.033 | 37.225 | 0.001 | 0.004 | 0.001 |
| Impurity element | Cu | Fe | Ge | Hg | Mn | Mo |
| Content (ppm) | 0.037 | 5.67 | 0.001 | 0.001 | 0.082 | 0.157 |
| Impurity element | Ni | Pb | Sb | Si | Sn | S |
| Content (ppm) | 0.401 | 0.036 | 0.001 | 3.624 | 0.003 | 53 |
As can be seen from table 1, the graphene material of example 1) has very low impurity content, which further verifies that the graphene material obtained by the preparation method of the present application has excellent application prospects.
The above description of the embodiments is only for aiding in the understanding of the method of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (8)
1. The sagger for preparing the graphene is characterized by comprising a sagger main body and a box cover, wherein the top of the sagger main body is provided with an opening, the box cover is covered on the top of the sagger main body, the sagger is made of high-density graphite, the high-density graphite is obtained by treating graphite raw materials at a high temperature, and the density of the high-density graphite is greater than or equal to 1.85g/cm 3 Wherein, the method comprises the steps of, wherein,
the sagger main body comprises an outer sagger wall body and an outer cavity formed by the outer sagger wall body, wherein the outer sagger wall body is provided with a notch so that the outer cavity is communicated with the outside;
the sagger main body is also provided with an inner box, the inner box comprises an inner box wall body and an inner cavity formed by the inner box wall body, the top of the inner box is provided with an opening, and the inner cavity is communicated with the outer cavity;
the box cover comprises a box cover top and a box cover wall body, wherein the box cover wall body is arranged in the outer cavity of the box body, and the height of the box cover wall body is smaller than that of the outer box wall body.
2. The sagger for preparing graphene according to claim 1, wherein the inner sagger wall is composed of a pair of first baffles and a pair of second baffles, and the height of the first baffles is greater than the height of the second baffles.
3. The sagger for preparing graphene according to claim 1, wherein the top of the sagger cover is composed of a top plate and a first recess formed around the top plate, and a minimum dimension of the first recess on a surface of the top plate in any direction is greater than a thickness of an outer sagger wall of the sagger body.
4. A sagger for preparing graphene according to claim 3, wherein at least a second recess is provided in the first recess, the second recess having a length in the x-direction greater than the thickness of the outer sagger wall of the sagger body.
5. The sagger for preparing graphene according to claim 1, wherein the high temperature treatment of the graphite raw material means that the graphite raw material is treated at 2400 ℃ to 3000 ℃ and is applied with a pressure of 1 to 3.6 atmospheres.
6. A method of preparing a graphene material using the sagger of any one of claims 1 to 5, comprising the steps of:
(1) Providing a graphite raw material;
(2) Oxidizing a graphite raw material, and then placing oxidized graphite in a sagger, and reducing the graphite in an inert atmosphere at 1000-1400 ℃ to obtain a graphene material, wherein the sagger is made of high-density graphite.
7. The method for preparing a graphene material using the above-mentioned sagger according to claim 6, wherein the time of the reduction in the step (2) is 20 minutes to 20 hours.
8. The method for preparing a graphene material using the above-mentioned sagger according to claim 6, wherein the temperature of the reduction in the step (2) is 1000 degrees celsius to 1100 degrees celsius, and the time of the reduction is 30 minutes to 12 hours.
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| CN113773067B (en) * | 2021-11-11 | 2022-01-18 | 长沙中瓷新材料科技有限公司 | Sagger based on cordierite and production process thereof |
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