Preparation method of belt-shaped graphene and application thereof to water-based conductive paste

Abstract

This invention discloses a method for preparing ribbon-shaped graphene and its application in aqueous conductive slurries. The ribbon-shaped graphene is formed by placing a metal catalyst in a reactor, introducing a carbon-containing gas source under a nitrogen atmosphere, and then, under the action of the gas flow and the catalyst, the carbon-containing gas decomposes to form ribbon-shaped graphene. This invention, through the design of a unique gas inlet angle and rate, achieves the preparation of graphene materials with unique morphologies based on traditional chemical vapor deposition methods. Furthermore, it can be used to prepare aqueous conductive slurries, showing broad application prospects in chemical batteries, photovoltaic power generation, heating films, and electromagnetic shielding materials.

Description

Technical Field

[0001] This invention relates to the technical field of graphene and conductive paste preparation, specifically to a method for preparing strip-shaped graphene and its application in aqueous conductive pastes. Background Technology

[0002] Graphene is a two-dimensional crystalline material composed of a single layer of hexagonally close-packed carbon atoms, approximately 0.335 nanometers thick. It possesses a perfect crystal structure and exhibits exceptional electrical conductivity, making it the most conductive material currently available. Its theoretical electron mobility is 15,000 cm⁻¹. 2 With a theoretical thermal conductivity of 5500 W / m·K, graphene has attracted widespread attention due to its excellent properties, including electrical conductivity, ultra-high specific surface area, unique two-dimensional network structure, high strength, and high electron mobility. This has spurred the rapid development of graphene preparation technology. Because of these numerous superior physicochemical properties, graphene is widely used in energy storage materials, environmental engineering, and sensitive sensing, earning it the nickname "black gold" or "king of new materials." Its potential applications are vast, and it has become a global focus and research hotspot.

[0003] Currently, graphene powders produced using conventional methods mainly exhibit a sheet-like structure, with limited research on varying length / width ratios of these sheets. Ribbon-like graphene is often obtained by cutting carbon nanotubes. Patent CN102602922B describes a method for preparing ribbon-like graphene, including the following steps: bonding single-walled, double-walled, or multi-walled carbon nanotube arrays onto a glass slide; ionizing the nanotubes under high voltage using liquid gallium as an ion source under a certain vacuum; and grinding for 5-12 hours to obtain ribbon-like graphene. Other researchers have also used chemical reagents or ultrasound to cut graphene into ribbons, but these methods are complex, have low yields, and produce graphene with low purity. In summary, the current technology for preparing ribbon-like graphene is complex and costly, and research on its controllable preparation methods and downstream application advantages is scarce, limiting in-depth research and development in the field of graphene. Summary of the Invention

[0004] This invention aims to provide a method for preparing ribbon graphene, enabling the rapid growth of graphene powder with controllable morphology. The invention also illustrates its application in conductive carbon paste. Conductive carbon paste made from this material has the advantages of low sheet resistance, good stability, and water-based environmental friendliness, and can be applied in fields such as lithium batteries, new energy, and heating films, showing broad application prospects.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing ribbon-shaped graphene and its application in aqueous conductive pastes, characterized in that the method for preparing the ribbon-shaped graphene includes the following steps:

[0007] (1) The metal catalyst is placed in a reactor containing a first inlet, a second inlet and an outlet, wherein the first inlet and the second inlet are located on the upper sides of the reactor and the angle between them and the horizontal plane is 45±10°, and the outlet is located at the lower part of the reactor and is horizontally set.

[0008] (2) Close the second inlet, introduce 5-300 sccm of nitrogen into the first inlet, open the outlet, fully replace the atmosphere in the reactor and maintain the internal pressure at 0.08-0.15 MPa, and then heat up to melt the catalyst.

[0009] (3) Open the second air inlet and introduce 5-100 sccm of carbon-containing gas, keep nitrogen gas in the air, and form ribbon graphene under the catalysis of the molten catalyst and blow it out of the reactor with the airflow. Collect it through the collection device connected to the air outlet to obtain the reaction product.

[0010] (4) The reaction product is washed to remove the catalyst, and then washed with water and dried to obtain ribbon graphene.

[0011] By designing a unique reactor, two gases are mixed at a specific angle and flow rate, and come into contact with the molten catalyst, reacting in a short time to form graphene material with a unique ribbon structure. The material is then discharged from the reaction device through the gas outlet and collected under the influence of airflow.

[0012] Further, the metal catalyst in step (1) is one or more of copper, iron, cobalt, nickel, and platinum.

[0013] Further, the carbon-containing gas in step (3) is one or a mixture of methane, natural gas, methanol, ethanol, dichloromethane, and tetrachloromethane. The input rate ratio of nitrogen to the carbon-containing gas source is 1-3:1.

[0014] Furthermore, the cleaning in step (4) uses one or more of sulfuric acid, hydrochloric acid, hydrogen peroxide, and hydrazine hydrate.

[0015] Furthermore, the thickness of the strip graphene obtained in step (4) is 0.5-5 nm, the width is 100-5000 nm, and the length is 10-100 μm.

[0016] An application of strip graphene in an aqueous conductive paste is characterized by dispersing the strip graphene in water and using it as a highly conductive paste for applications in chemical batteries, photovoltaic power generation, heating films, and electromagnetic shielding materials. The resulting aqueous conductive paste possesses advantages such as low resistivity, good stability, and water-based environmental friendliness, and can be applied in fields such as lithium batteries, new energy, and heating films, showing broad application prospects.

[0017] Furthermore, the aqueous conductive slurry is prepared by the following method: strip graphene, dispersant, and deionized water are mixed evenly in a mass ratio of 5:1:94, and homogenized 3-5 times under 80-90 MPa conditions using a microfluidic homogenizer to obtain the aqueous graphene conductive slurry.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. By adjusting the catalyst and gas source, this invention obtains graphene powder that can be produced continuously, overcoming the problems of high cost, low yield, long graphene growth time and stringent preparation process requirements of traditional vapor deposition method, and meeting the commercial needs of large-scale graphene production.

[0020] 2. By adjusting the ratio of nitrogen inlet gas to carbon-containing gas inlet gas rate and the angle between nitrogen and gas outlet, ribbon-shaped graphene with controllable length, width, and thickness was obtained, expanding the morphological types of graphene and enabling the large-scale preparation of ribbon-shaped graphene powder.

[0021] 3. Compared to the sheet-like morphology of conventional graphene powder, the ribbon-like graphene prepared in this patent can maintain more effective connectivity during dispersion and processing in a medium, forming interlocking sheets. Its ribbon structure also endows the graphene powder with certain linear winding characteristics, resulting in a graphene carbon paste resistivity of 0.2-2.0*10⁻⁶. -3 With a conductivity of Ω·cm, it exhibits extremely superior conductivity and conductivity stability, making it applicable to fields such as lithium battery materials, conductive carbon paste, and heating paste. Furthermore, no organic solvents are used in the preparation of this graphene paste, making the entire process environmentally friendly and pollution-free, and it has excellent application prospects. Attached Figure Description

[0022] Figure 1 This is a scanning electron microscope (SEM) image of the ribbon graphene obtained in Example 1. Detailed Implementation

[0023] The present invention will be described in detail below with reference to the embodiments. The following embodiments are implemented on the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0024] Example 1

[0025] (1) Copper / cobalt is placed in a reactor containing a first inlet, a second inlet and an outlet at a mass ratio of 2 / 1. The first inlet and the second inlet are located on the upper sides of the reactor and are at an angle of 45° with the horizontal plane. The outlet is located at the lower part of the reactor and is set horizontally.

[0026] (2) Close the second inlet, introduce 5 sccm of nitrogen into the first inlet, open the outlet, fully replace the atmosphere in the reactor and maintain the internal pressure at 0.08 MPa, then heat to 1650℃ to melt the catalyst.

[0027] (3) Open the second inlet and introduce 5 sccm of methane gas, keep nitrogen gas in, and keep the nitrogen to methane input rate ratio at 1:1. Under the catalysis of the molten catalyst, strip graphene is formed and blown out of the reactor with the gas flow. The reaction product is collected by the collection device connected to the outlet.

[0028] (4) The catalyst was removed by washing the reaction product with hydrogen peroxide, and then the product was washed with water and dried to obtain ribbon graphene.

[0029] The resulting ribbon-like graphene has a thickness of 3-5 nm, a width of 100-800 nm, and a length of 10-30 μm, with a morphology as follows: Figure 1 As shown, the above-mentioned strip graphene, K30, and deionized water are mixed evenly in a mass ratio of 5:1:94, and homogenized three times using a microfluidic homogenizer at 80-90 MPa to obtain an aqueous graphene conductive slurry with a resistivity of up to 1.0*10⁻⁶. -3 Ω·cm.

[0030] Example 2

[0031] (1) Copper / cobalt is placed in a reactor containing a first inlet, a second inlet and an outlet at a mass ratio of 2 / 1. The first outlet and the second outlet are located on the upper sides of the reactor and are at an angle of 35° with the horizontal plane. The outlet is located horizontally at the lower part of the reactor.

[0032] (2) Close the second outlet, introduce 40 sccm of nitrogen into the first inlet, open the outlet, fully replace the atmosphere in the reactor and maintain the internal pressure at 0.08 MPa, and then heat to 1650℃ to melt the catalyst.

[0033] (3) Open the second gas outlet and introduce 20 sccm of natural gas, keep nitrogen gas in, and keep the nitrogen to methane input rate ratio at 2:1. Under the catalysis of the molten catalyst, strip graphene is formed and blown out of the reactor with the gas flow. The reaction product is collected by the collection device connected to the gas outlet.

[0034] (4) The catalyst was removed by washing the reaction product with hydrogen peroxide, and then the product was washed with water and dried to obtain ribbon graphene.

[0035] The resulting ribbon-like graphene has a thickness of 1.5-3.5 nm, a width of 100-800 nm, and a length of 10-30 μm. The above-mentioned ribbon-like graphene, K30, and deionized water are mixed uniformly in a mass ratio of 5:1:94, and homogenized three times using a microfluidic homogenizer at 80-90 MPa to obtain an aqueous graphene conductive slurry with a resistivity of up to 0.5 × 10⁻⁶. -3

[0036] Ω·cm.

[0037] Example 3

[0038] (1) Copper / nickel is placed in a reactor containing a first inlet, a second inlet and an outlet at a mass ratio of 1 / 1. The first outlet and the second outlet are located on the upper sides of the reactor and are at an angle of 55° with the horizontal plane. The outlet is located at the lower part of the reactor and is set horizontally.

[0039] (2) Close the second outlet, introduce 300 sccm of nitrogen into the first inlet, open the outlet, fully replace the atmosphere in the reactor and maintain the internal pressure at 0.15 MPa, and then heat to 1800℃ to melt the catalyst.

[0040] (3) Open the second outlet and introduce 100 sccm of dichloromethane gas, keep nitrogen gas in, and keep the nitrogen to methane input rate ratio at 3:1. Under the catalysis of the molten catalyst, strip graphene is formed and blown out of the reactor with the gas flow. The reaction product is collected by the collection device connected to the outlet.

[0041] (4) The catalyst was removed by washing the reaction product with hydrogen peroxide, and then the product was washed with water and dried to obtain ribbon graphene.

[0042] The resulting ribbon-like graphene has a thickness of 0.5-2.5 nm, a width of 4200-5000 nm, and a length of 80-100 μm. The above-mentioned ribbon-like graphene, K30, and deionized water are mixed uniformly in a mass ratio of 5:1:94, and homogenized three times using a microfluidic homogenizer at 80-90 MPa to obtain an aqueous graphene conductive slurry with a resistivity of up to 2.0 × 10⁻⁶. -3

[0043] Ω·cm.

[0044] Comparative Example 1

[0045] (1) Place copper / cobalt in a horizontal tube furnace at a mass ratio of 1:1;

[0046] (2) Introduce 20 sccm of nitrogen gas from one end of the tube furnace, open the gas outlet, fully replace the atmosphere in the reactor and maintain the internal pressure at a slightly positive pressure, and then heat up to 1800℃ to melt the catalyst.

[0047] (3) Nitrogen gas of 20 sccm and methane gas of 20 sccm are introduced simultaneously from one end of the tube furnace. Under the catalysis of the molten catalyst, the strip graphene is formed and blown out of the tube furnace with the gas flow. The gas is collected by the collection device connected to the gas outlet to obtain the reaction product.

[0048] (4) The catalyst was removed by washing the reaction product with hydrogen peroxide, and then the product was washed with water and dried to obtain graphene powder.

[0049] The obtained graphene powder has a thickness of 5-10 nm, a width of 5-20 μm, and a length of 10-20 μm, exhibiting an overall sheet-like structure. The graphene powder, K30, and deionized water were mixed uniformly at a mass ratio of 5:1:94, and homogenized three times using a microfluidic homogenizer at 80-90 MPa. The resulting slurry had a resistivity of 2.0 × 10⁻⁶. 1 The Ω·cm is significantly higher than that of conductive pastes prepared from strip graphene.

[0050] Comparative Example 2

[0051] (1) Copper / cobalt is placed in a reactor containing a first inlet, a second inlet and an outlet at a mass ratio of 1 / 1. The first outlet and the second outlet are located on the upper sides of the reactor and are at an angle of 45° with the horizontal plane. The outlet is located horizontally at the lower part of the reactor.

[0052] (2) Close the second outlet, introduce nitrogen into the first inlet, open the outlet, fully replace the atmosphere in the reactor and maintain the internal pressure at 0.08 MPa, then heat to 1800℃ to melt the catalyst.

[0053] (3) Open the second gas outlet and introduce 20 sccm of methane gas. Stop the nitrogen gas supply. Under the catalysis of the molten catalyst, strip graphene is formed and blown out of the reactor with the gas flow. The reaction product is collected by the collection device connected to the gas outlet.

[0054] (4) The catalyst was removed by washing the reaction product with hydrogen peroxide, and then the product was washed with water and dried to obtain graphene powder.

[0055] The obtained graphene powder has a thickness of 3-5 nm, a width of 10-30 μm, and a length of 20-50 μm, exhibiting an overall sheet-like structure. The graphene powder, K30, and deionized water were mixed uniformly at a mass ratio of 5:1:94, and homogenized three times using a microfluidic homogenizer at 80-90 MPa. The resulting slurry had a resistivity of 1.0 × 10⁻⁶. 2The Ω·cm is significantly higher than that of conductive pastes prepared from strip graphene.

[0056] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing ribbon-shaped graphene, characterized in that, Includes the following steps: (1) The metal catalyst is placed in a reactor containing a first inlet, a second inlet and an outlet, wherein the first inlet and the second inlet are located on the upper sides of the reactor and the angle between them and the horizontal plane is 45±10°, and the outlet is located horizontally at the lower part of the reactor. (2) Close the second inlet, introduce 5-300 sccm of nitrogen into the first inlet, open the outlet, fully replace the atmosphere in the reactor and maintain the internal pressure at 0.08-0.15 MPa, and then heat up to melt the catalyst; (3) Open the second air inlet and introduce 5-100 sccm of carbon-containing gas, keep nitrogen gas in, and form ribbon graphene under the catalysis of the molten catalyst and blow it out of the reactor with the gas flow. Collect it through the collection device connected to the gas outlet to obtain the reaction product. (4) The reaction product is washed to remove the catalyst, and then washed with water and dried to obtain ribbon graphene; The metal catalyst in step (1) is one or more of copper, iron, cobalt, nickel, and platinum; The carbon-containing gas mentioned in step (3) is one or a mixture of methane, natural gas, methanol, ethanol, dichloromethane, and tetrachloromethane; The ratio of the nitrogen to the carbon-containing gas source input rate in step (3) is 1-3:

1.

2. The method according to claim 1, characterized in that, The cleaning in step (4) is carried out by reaction cleaning using one or more of the following reagents: sulfuric acid, hydrochloric acid, hydrogen peroxide, and hydrazine hydrate.

3. The method according to claim 1, characterized in that, The thickness of the strip graphene in step (4) is 0.5-5nm, the width is 100-5000nm, and the length is 10-100um.

4. The application of the ribbon graphene prepared by the method described in claim 1 in aqueous conductive pastes, characterized in that, After dispersing in water, strip graphene is used as a highly conductive slurry in the fields of chemical batteries, photovoltaic power generation, heating films, and electromagnetic shielding materials.

5. The application according to claim 4, characterized in that, The water-based conductive slurry is prepared by the following method: strip graphene, dispersant and deionized water are mixed evenly in a mass ratio of 5:1:94, and homogenized 3-5 times under 80-90MPa conditions by a microfluidic homogenizer to obtain the water-based graphene conductive slurry.

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