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JP-7857318-B2 - Graphene powder, method of preparing the same, and use thereof

JP7857318B2JP 7857318 B2JP7857318 B2JP 7857318B2JP-7857318-B2

Inventors

  • 孫賽
  • 張絲雨
  • 董文▲チェン▼
  • 高煥新

Assignees

  • 中国石油化工股▲ふん▼有限公司
  • 中国石油化工股▲ふん▼有限公司上海石油化工研究院

Dates

Publication Date
20260512
Application Date
20210927
Priority Date
20210422

Claims (13)

  1. Graphene powder, which is a laminate of graphene sheets, wherein the graphene sheets contain 1 to 10 layers of graphene, and the Raman spectrum of the graphene powder contains a D peak and a G peak with peak heights I and D and I and G , respectively, and the Raman spectrum is tested using an Invia/Reflrx Laser Micro-Raman spectrometer with a laser of wavelength 785 nm as the excitation light source, and the I/ D /I/ G ratio is 0.03 to 0.10, and the graphene powder has voids between the graphene sheets, and the particle size of the graphene powder measured by dynamic light scattering is 20 to 35 μm, and the graphene powder has a carbon content of 99.50% or more and an oxygen content of 300 ppm or less, based on the mass of the graphene powder, and the graphene powder has a specific surface area of 50 to 300 m² /g.
  2. The graphene powder according to claim 1, wherein the graphene powder has a specific surface area of 100 to 250 m² /g.
  3. The graphene powder according to claim 1, wherein the graphene powder has a tap density of 0.02 to 0.04 g/ cm³ .
  4. The graphene powder according to claim 1, wherein the conductivity of the graphene powder, as measured using an ST-2258C multi-function digital four-probe tester, is 500 to 5000 S/cm.
  5. The graphene powder according to any one of claims 1 to 4, wherein when the graphene sheet is heat-treated in an air atmosphere, the thermal decomposition initiation temperature of the graphene sheet is 600°C or higher.
  6. The graphene powder according to any one of claims 1 to 4, wherein when the graphene sheet is heat-treated at 800°C in an air atmosphere, the heat loss of the graphene sheet is 10% or less.
  7. (1) A step of pre-expanding expandable graphite to obtain pre-expanded graphite; (2) After mixing the pre-expanded graphite obtained in step (1), a wetting agent, and a solvent, the resulting mixture is subjected to a first high-pressure homogenization and a second high-pressure homogenization to obtain a slurry containing graphene powder. Here, the pressure of the second high-pressure homogenization is 10 to 20 MPa higher than the pressure of the first high-pressure homogenization; (3) The process includes a step of drying the slurry containing the graphene powder obtained in step (2) to obtain graphene powder, The wetting agent in step (2) is an aliphatic amine polyoxyethylene ether, and the HLB value of the aliphatic amine polyoxyethylene ether is 12 or higher. A method for preparing graphene powder according to any one of claims 1 to 4 .
  8. The method according to claim 7 , wherein the pre-expanded graphite obtained in step (1) has an expansion rate of 200 to 300 times that of the expandable graphite before pre-expansion.
  9. The method according to claim 7 , wherein the pre-expansion in step (1) includes the steps of heating expandable graphite to 800 to 950°C and expanding the expandable graphite for 10 to 60 seconds to obtain pre-expanded graphite.
  10. The method according to claim 7, wherein in step (2), the first high-pressure homogenization is performed at a pressure of 30 to 40 MPa for a duration of 20 to 60 minutes, and the second high-pressure homogenization is performed at a pressure of 40 to 50 MPa for a duration of 10 to 30 minutes.
  11. The method according to claim 7 , wherein the pre-expanded graphite obtained in step (1) and the wetting agent are supplied in step (2) in a mass ratio of 1:0.01 to 0.1.
  12. In step (3), drying is spray drying or freeze-drying. The conditions for the spray drying are that the air inlet temperature is 300 to 350°C, the air inlet temperature is 200 to 250°C higher than the air outlet temperature, the air outlet temperature is 100 to 130°C, and the rotation speed of the centrifugal disk of the spray drying apparatus is 20,000 to 30,000 rpm. The method according to claim 7, wherein the freeze-drying conditions are: a cooling trap temperature of -75 to -70°C, a shelf partition plate temperature of -65 to -60°C, a heating rate of 0.1 to 0.5°C/min, a time of 26 to 30 hours to raise the temperature from the shelf partition plate temperature to 0°C, and a vacuum level of 0.5 to 5 Pa.
  13. Use of graphene powder according to any one of claims 1 to 4 , or graphene powder prepared by the method according to any one of claims 7 to 12 , in conductive composite materials, anticorrosive coatings, or heat dissipation composite materials.

Description

Detailed description of the invention [Technical Field] This disclosure relates to graphene materials, and more particularly to graphene powder, as well as methods for preparing and using the same. [Background technology] Graphene is a carbon material with a single-layer, two-dimensional honeycomb lattice structure linked by sp2 hybridized carbon atoms. Graphene can possess ultra-high electrical conductivity (electron mobility of 10,000 cm² /(V·s)), ultra-high thermal conductivity (approximately 5,000 W/(m·K)), and a large specific surface area. Graphene has the potential for widespread applications in fields such as electronics, aerospace, military, and new energy. Graphene is expected to revolutionize modern electronic technology. Years of research and development have resulted in significant advancements in large-scale graphene production technology, processing equipment, and product quality. However, many important technical challenges remain. For example, the current method of preparing graphene powder, employed by many companies, is still a redox process, which can contain many strong acids and oxidizing substances, leading to serious contamination problems. Simultaneously, the manufactured graphene powder contains numerous defects, making it difficult to control product quality, limiting downstream applications and severely restricting the industrialization of graphene. CN102838110B proposes a process involving the combustion and synthesis of a mixed powder of magnesium powder and carbonate powder to obtain graphene powder. This process is simple to operate and allows for continuous production. However, it requires high-purity magnesium powder. Because graphene uses carbonate as its carbon source, it is not economically viable. Furthermore, graphene powder may have low crystallinity and quality, which somewhat limits its downstream applications. CN107539973B proposes a process that involves obtaining a graphene rally using graphite, an intercalation expander, and chlorosulfonic acid as raw materials, followed by freeze-drying to obtain graphene powder. The graphene obtained through this process may have a perfect crystalline structure. This process is simple to operate and low-cost. However, ultrasonic stripping is inefficient and can result in poor processing uniformity, and removing impurities other than carbon ions from the product is difficult, making large-scale application challenging. CN105540575A discloses a method for preparing graphene by exfoliating it using a high-pressure homogenizer, using graphite, an intercalation agent, and a dispersant as raw materials to obtain graphene powder using a high-pressure homogenizer. This method can achieve high graphene yields. However, it is complex, requires large amounts of organic solvents, and pollutes the environment. Simultaneously, the intercalation agent in the solution may remain in the graphene product, making purification difficult and potentially negatively impacting the quality of the graphene product. Therefore, large-scale application of this product in downstream applications such as lithium-ion batteries may be difficult. Therefore, developing a graphene powder with excellent dispersion properties, easy preparation, low cost, and high quality is a technical challenge in this field. [Summary of the Invention] The object of the present invention is to solve one or more of the problems of conventional graphene powder, such as low conductivity, non-uniform dispersion in solvents, tendency to aggregate, and complexity of preparation . Therefore, this disclosure provides graphene powder, a method for preparing the same, and its use. The graphene powder of this disclosure has advantages such as fewer defects and high conductivity, and can be applied to conductive composite materials, anticorrosive coatings, and heat dissipation composite materials. In particular, when used in lithium-ion batteries, it can significantly reduce the internal resistance of electrodes and improve the stability of the battery at any current rate. A first aspect of the present disclosure provides a graphene powder which is a laminate of graphene sheets, wherein the Raman spectrum of the graphene powder includes a D peak and a G peak with peak heights I D and I G , respectively, and I D /I G is 0.10 or less. In a second aspect of this disclosure, (1) A step of pre-expanding expandable graphite to obtain pre-expanded graphite; (2) After mixing the pre-expanded graphite obtained in step (1), a wetting agent, and a solvent, the resulting mixture is subjected to a first high-pressure homogenization and a second high-pressure homogenization to obtain a slurry containing graphene powder. Here, the pressure of the second high-pressure homogenization is 10 to 20 MPa higher than the pressure of the first high-pressure homogenization; A method for preparing graphene powder is provided, comprising the step of drying a slurry containing the graphene powder obtained in step (2) t