Modified conductive graphene as well as preparation method and application thereof

Abstract

The invention relates to modified conductive graphene and a preparation method and application thereof, and relates to the field of conductive materials.The preparation method comprises the following steps that aluminum-silicon alloy powder is added into an alkaline solution for a first stirring reaction, then washing and drying are conducted, and a first silicon carrier is obtained; carrying out heating reaction on the first silicon carrier and magnesium powder in an inert gas atmosphere, and then carrying out acid pickling and drying to obtain a second silicon carrier; and dipping the second silicon carrier in a nickel-containing solution, drying and reducing to obtain a third silicon carrier, and the like. Compared with the prior art, three-dimensional porous silicon is adopted as a carrier, a graphene layer is grown on the surface of the carrier through chemical deposition, and polyamide-amine (PAMAM) is further grafted to the surface of graphene to enhance the compatibility with a polymer and inhibit agglomeration, so that the modified conductive graphene material with high conductivity and excellent compatibility is obtained; the conductivity of fuel cells and the like can be obviously improved, and the application prospect is wide.

Description

Technical Field

[0001] This invention relates to the field of conductive materials, and more particularly to a modified conductive graphene, its preparation method, and its applications. Background Technology

[0002] In the field of conductive materials, with the rapid development of industries such as electronics and energy, the demand for materials with high conductivity and good compatibility is becoming increasingly urgent. As a key component of many advanced technologies, the performance of conductive materials directly affects the operating efficiency and stability of related equipment and systems. In many application scenarios such as fuel cells, supercapacitors, and conductive composite materials, conductive materials must not only possess efficient charge transport capabilities but also have good compatibility with matrix materials or other components to ensure the full realization of overall performance.

[0003] Graphene, a two-dimensional material composed of carbon atoms, has attracted much attention since its discovery due to its unique electronic structure and excellent physicochemical properties. It possesses extremely high carrier mobility, excellent electrical and thermal conductivity, and theoretically holds enormous application potential in the field of conductive materials. However, in practical applications, graphene has also revealed some problems that urgently need to be solved.

[0004] On the one hand, the strong van der Waals forces between graphene sheets make graphene prone to aggregation. Aggregated graphene not only has a significantly reduced specific surface area, but its internal conductive pathways are also destroyed, resulting in a significant decrease in conductivity. When composited with other materials, aggregated graphene is difficult to disperse uniformly and cannot form good interfacial bonding, thus affecting the overall performance of the composite material and limiting its large-scale application in many fields.

[0005] On the other hand, although graphene itself possesses excellent conductivity, in certain applications, such as when it is combined with a polymer matrix to prepare conductive composite materials, the compatibility between graphene and the polymer is poor. Due to the significant differences in their chemical structure and physical properties, graphene is difficult to disperse uniformly in the polymer matrix, and the interfacial bonding force between graphene and the polymer is weak, making it prone to delamination under stress or during use. This results in unstable conductivity and mechanical properties of the composite material, failing to meet the requirements of practical applications. Summary of the Invention

[0006] To address the above problems, this invention provides a modified conductive graphene, its preparation method, and its applications.

[0007] In a first aspect, the present invention provides a method for preparing modified conductive graphene, comprising the following steps: Aluminum-silicon alloy powder was added to an alkaline solution for a first stirring reaction, followed by washing and drying to obtain the first silicon support. Under an inert gas atmosphere, the first silicon support and magnesium powder are heated and reacted, followed by acid washing and drying to obtain the second silicon support; The second silicon support was immersed in a nickel-containing solution, then dried and reduced to obtain the third silicon support; A graphene layer was deposited on the surface of the third silicon carrier using chemical vapor deposition to obtain the first graphene. The first graphene was immersed in a PAMAM ethanol solution for a second stirring reaction to obtain the modified conductive graphene.

[0008] Further, the steps of adding aluminum-silicon alloy powder to an alkaline solution for a first stirring reaction, followed by washing and drying to obtain the first silicon support include the following processes: The aluminum-silicon alloy powder was added to a NaOH solution with a concentration of 1~1.5 mol / L and reacted at 80~90℃ for 2~3 hours. After washing until neutral, the powder was dried under vacuum to obtain the first silicon support.

[0009] Furthermore, the mass fraction of Al in the aluminum-silicon alloy powder is 27%~35%, the particle size of the aluminum-silicon alloy powder is 2~5μm, and the mass ratio of the aluminum-silicon alloy powder to the NaOH solution is 1:(10~15).

[0010] Further, the steps of heating and reacting the first silicon support and magnesium powder under an inert gas atmosphere, followed by acid washing and drying to obtain the second silicon support include the following processes: Under an argon atmosphere, the first silicon support and the magnesium powder in a mass ratio of 1:(2~3) are heated at 600~680℃ for 3~5h. After the reaction is completed, 1mol / L HCl solution is added for acid washing for 30~45min, followed by vacuum drying to obtain the second silicon support.

[0011] Further, the step of immersing the second silicon support in a nickel-containing solution, followed by drying and reduction to obtain the third silicon support includes the following processes: The second silicon support was immersed in a 0.1 mol / L Ni(NO3)2 solution, dried, and then reduced for 1 to 1.5 h in a H2 / Ar mixed gas with a volume ratio of 1:(8~9) at a temperature of 400~460°C to obtain the third silicon support.

[0012] Furthermore, a graphene layer is deposited on the surface of the third silicon carrier using chemical vapor deposition to obtain the first graphene, comprising the following processes: The first graphene was obtained by introducing 20-25 sccm CH4 and 100-120 sccm H2 and growing at 1050-1100℃ for 30-40 min, followed by cooling to room temperature.

[0013] Further, the step of immersing the first graphene in a PAMAM ethanol solution for a second stirring reaction to obtain the second graphene includes the following process: The first graphene was immersed in a 0.5-1 wt% PAMAM ethanol solution, and the second stirring reaction was carried out at 80-90°C for 5-7 hours. After filtration and vacuum drying, the modified conductive graphene was obtained.

[0014] Secondly, based on the same inventive concept, the present invention provides a modified conductive graphene, which is prepared by the method described in any one of the first aspects.

[0015] Thirdly, based on the same inventive concept, this invention provides an application of the modified conductive graphene described in the second aspect in the preparation of capacitors and fuel cells.

[0016] Furthermore, the preparation of the bipolar plate of the fuel cell includes the following steps: 10-15 parts by weight of modified graphene, 20-25 parts by weight of polyethylene dioxythiophene, 10-15 parts by weight of epoxy resin, and 8-13 parts by weight of carbon nanotubes were added to 50-60 parts by weight of N-methylpyrrolidone solvent and ultrasonically dispersed. The ultrasonic power was 200-300W and the ultrasonic time was 30-60min to obtain a slurry. The slurry is coated onto a graphite substrate and pre-cured at 120-125°C for 1-1.5 hours, followed by hot pressing at 180-185°C and 10-12 MPa for 2-2.5 hours to form a 0.5 mm thick bipolar plate.

[0017] The technical solutions provided in the embodiments of the present invention have at least the following advantages compared with the prior art: This invention provides a modified conductive graphene, its preparation method, and its applications. Compared with the prior art, this invention uses three-dimensional porous silicon as a carrier and chemically deposits graphene layers on its surface. Furthermore, polyamide-amine (PAMAM) is grafted onto the graphene surface to enhance compatibility with polymers and inhibit agglomeration, thereby obtaining a modified conductive graphene material with high conductivity and excellent compatibility. This material can significantly improve conductivity in applications such as fuel cells and has broad application prospects. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this invention can be purchased commercially or prepared using existing methods. Furthermore, unless otherwise specified or detailed, the steps and parameters involved in this invention can be performed according to existing preparation processes or directly using existing equipment; these will not be elaborated upon further in this document.

[0020] The technical solution provided by this invention is as follows: In a first aspect, the present invention provides a method for preparing modified conductive graphene, comprising the following steps: Aluminum-silicon alloy powder was added to an alkaline solution for a first stirring reaction, followed by washing and drying to obtain the first silicon support. Under an inert gas atmosphere, the first silicon support and magnesium powder are heated and reacted, followed by acid washing and drying to obtain the second silicon support; The second silicon support was immersed in a nickel-containing solution, then dried and reduced to obtain the third silicon support; A graphene layer was deposited on the surface of the third silicon carrier using chemical vapor deposition to obtain the first graphene. The first graphene was immersed in a PAMAM ethanol solution for a second stirring reaction to obtain the modified conductive graphene.

[0021] Compared to existing technologies, this invention utilizes three-dimensional porous silicon as a carrier and chemically deposits a graphene layer on its surface. Furthermore, polyamide-amine (PAMAM) is grafted onto the graphene surface to enhance compatibility with the polymer and inhibit agglomeration. This results in a modified conductive graphene material with high conductivity and excellent compatibility, significantly improving conductivity in applications such as fuel cells, and showing broad application prospects. Specifically: Step 1: Alkaline treatment of aluminum-silicon alloy to prepare the first silicon carrier In aluminum-silicon alloys, aluminum (Al) undergoes a violent reaction in alkaline solutions (such as NaOH), dissolving to form soluble aluminates, while silicon (Si) undergoes only a slight reaction or no reaction due to the formation of a dense silicon oxide protective layer on its surface or its inherent alkali resistance. After washing to remove residual aluminates and drying, high-purity silicon particles are obtained, which serve as precursors for three-dimensional porous silicon carriers.

[0022] Step 2: Magnesium reduction to prepare the second silicon support In an inert atmosphere (such as Ar), silicon support reacts with magnesium powder at high temperature to generate magnesium silicide. Subsequent acid washing (such as HCl) dissolves the magnesium silicide. Due to the local reaction-dissolution difference on the surface of silicon particles, nanoscale pores are formed, constructing a three-dimensional porous structure. This structure significantly increases the specific surface area, providing abundant active sites for subsequent graphene deposition, while inhibiting graphene agglomeration.

[0023] Step 3: Preparation of the third silicon support by supporting nickel catalyst A silicon support is impregnated with a nickel-containing solution, and the nickel salt precursor is adsorbed into the pores by drying. After reduction, the nickel ions are reduced to metallic nickel nanoparticles, which are uniformly dispersed on the surface and in the pores of the silicon support. Nickel, as a catalyst for chemical vapor deposition (CVD), can lower the energy barrier for carbon source decomposition and promote the orderly growth of graphene.

[0024] Step 4: Chemical vapor deposition to grow graphene layers At high temperatures, the carbon source gas undergoes pyrolysis on the surface of the nickel catalyst, resulting in the dissolution, diffusion, and precipitation of carbon atoms, forming a continuous graphene layer on the silicon support surface. The high specific surface area and ordered pore structure of the three-dimensional porous silicon promote gas diffusion, achieving uniform graphene coverage. The sp² hybrid carbon network of graphene endows the material with high electrical conductivity, while the silicon support provides mechanical support, preventing graphene peeling or curling.

[0025] Step 5: PAMAM grafting modification Surface functionalization mechanism: Polyamide-amine (PAMAM) dendritic molecules are grafted onto the graphene surface through amidation reactions or electrostatic adsorption with oxygen-containing functional groups (such as carboxyl and hydroxyl groups) on the graphene surface via their surface amino groups. The dendritic structure of PAMAM creates a steric hindrance effect, inhibiting π-π stacking between graphene sheets; its hydrophilic segments enhance compatibility with polar polymers (such as proton exchange membranes in Nafion fuel cells), reducing interfacial defects. In addition, the nitrogen atoms of PAMAM can introduce additional charge carriers, synergistically improving the conductivity of the composite material with graphene.

[0026] In one embodiment of the present invention, the steps of adding aluminum-silicon alloy powder to an alkaline solution for a first stirring reaction, followed by washing and drying to obtain a first silicon support include the following processes: The aluminum-silicon alloy powder is added to a NaOH solution with a concentration of 1~1.5 mol / L (preferably 1.0 mol / L NaOH) and reacted at 80~90℃ (preferably 85℃) for 2~3 h (preferably 2.5 h). After washing until neutral, the powder is dried under vacuum to obtain the first silicon support.

[0027] In one embodiment of the present invention, the mass fraction of Al in the aluminum-silicon alloy powder is 27% to 35%, such as commercially available products with product model ZY-AlSi70 (i.e., Al content of 30%); the particle size of the aluminum-silicon alloy powder is 2 to 5 μm; the mass ratio of the aluminum-silicon alloy powder to the NaOH solution is 1:(10 to 15), and the preferred mass ratio of the aluminum-silicon alloy powder to the NaOH solution is 1:12.

[0028] In one embodiment of the present invention, the steps of heating and reacting the first silicon support and magnesium powder under an inert gas atmosphere, followed by acid washing and drying to obtain the second silicon support include the following processes: Under an argon atmosphere, the first silicon support and the magnesium powder in a mass ratio of 1:(2~3) are heated at 600~680℃ (preferably 650℃) for 3~5h (preferably 4h); after the reaction is completed, 1mol / L HCl solution is added for acid washing for 30~45min, and then vacuum dried to obtain the second silicon support.

[0029] In one embodiment of the present invention, the step of immersing the second silicon support in a nickel-containing solution, followed by drying and reduction to obtain the third silicon support includes the following process: The second silicon support is immersed in a 0.1 mol / L Ni(NO3)2 solution, dried, and then reduced for 1 to 1.5 h in a H2 / Ar mixed gas with a volume ratio of 1:(8~9) and at a temperature of 400~460℃ (preferably 450℃) to obtain the third silicon support.

[0030] In one embodiment of the present invention, a graphene layer is deposited on the surface of the third silicon carrier by chemical vapor deposition to obtain the first graphene, comprising the following processes: The first graphene is obtained by introducing 20-25 sccm CH4 (preferably 22 sccm) and 100-120 sccm H2 (preferably 115 sccm) and growing at 1050-1100℃ (preferably 1080℃) for 30-40 minutes and then cooling to room temperature.

[0031] In one embodiment of the present invention, the step of immersing the first graphene in a PAMAM ethanol solution to carry out a second stirring reaction to obtain the second graphene includes the following process: The first graphene was immersed in a 0.5-1 wt% PAMAM ethanol solution, and the second stirring reaction was carried out at 80-90°C for 5-7 hours. After filtration and vacuum drying, the modified conductive graphene was obtained. Specifically, the PAMAM used in subsequent examples and comparative examples can be commercially available products such as those from Weihai Chenyuan Molecular New Materials Co., Ltd., with the chemical formula C0.24 H 52 N 10 O4S2 has the following chemical structure: .

[0032] Secondly, based on the same inventive concept, the present invention provides a modified conductive graphene, which is prepared by the method described in any one of the first aspects.

[0033] Thirdly, based on the same inventive concept, this invention provides an application of the modified conductive graphene described in the second aspect in the preparation of capacitors and fuel cells.

[0034] As one embodiment of the present invention, the preparation of the bipolar plate of the fuel cell includes the following steps: 10-15 parts by weight (preferably 12 parts by weight) of modified graphene, 20-25 parts by weight (preferably 24 parts by weight) of polyethylene dioxythiophene, 10-15 parts by weight (preferably 12 parts by weight) of epoxy resin, and 8-13 parts by weight (preferably 10 parts by weight) of carbon nanotubes are added to 50-60 parts by weight (preferably 55 parts by weight) of N-methylpyrrolidone solvent and ultrasonically dispersed. The ultrasonic power is 200-300W and the ultrasonic time is 30-60min to obtain a slurry. The slurry is coated onto a graphite substrate and pre-cured at 120-125°C for 1-1.5 hours, followed by hot pressing at 180-185°C and 10-12 MPa for 2-2.5 hours to form a 0.5 mm thick bipolar plate.

[0035] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed according to national standards. If no corresponding national standard exists, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0036] Example 1 This example provides a modified conductive graphene, the preparation method of which includes the following steps: Step (1): Add aluminum-silicon alloy powder (30% Al by mass, 3μm particle size) to a 1.0mol / L NaOH solution, wherein the mass ratio of the aluminum-silicon alloy powder to the NaOH solution is 1:12, react at 85℃ for 2.5h, wash until neutral, and vacuum dry to obtain the first silicon support; Step (2): Under an argon atmosphere, the first silicon support obtained in step (1) with a mass ratio of 1:2 and magnesium powder are heated and reacted at 650°C for 4 hours; after the reaction is completed and cooled to room temperature, 1 mol / L HCl solution is added for acid washing for 40 minutes, and then vacuum dried to obtain the second silicon support. Step (3): The second silicon support obtained in step (2) is immersed in a 0.1 mol / L Ni(NO3)2 solution with a mass ratio of 1:5. After drying, it is subjected to a reduction reaction at 450°C for 1.5 h in a H2 / Ar mixed gas with a volume ratio of 1:9 to obtain the third silicon support. Step (4): Graphene layer is deposited on the surface of the third silicon carrier obtained in step (3) by chemical vapor deposition, 22 sccm CH4 and 115 sccm H2 are introduced, and growth is carried out at 1080℃ for 35 min to obtain the first graphene. Step (5): Immerse the first graphene obtained in step (4) in 0.8wt% PAMAM ethanol solution, the mass ratio of the first graphene to PAMAM ethanol solution is 1:7, stir and react at 85℃ for 6h, filter, and vacuum dry to obtain the modified conductive graphene.

[0037] Example 2 This example provides a modified conductive graphene, the preparation method of which includes the following steps: Step (1): Add aluminum-silicon alloy powder (30% Al by mass, 3μm particle size) to a 1.0mol / L NaOH solution, wherein the mass ratio of the aluminum-silicon alloy powder to the NaOH solution is 1:12, react at 85℃ for 2.5h, wash until neutral, and vacuum dry to obtain the first silicon support; Step (2): Under an argon atmosphere, the first silicon support and magnesium powder obtained in step (1) with a mass ratio of 1:3 were heated and reacted at 640°C for 5 hours; after the reaction was completed and cooled to room temperature, 1 mol / L HCl solution was added for acid washing for 40 minutes, and then vacuum dried to obtain the second silicon support. Step (3): The second silicon support obtained in step (2) is immersed in a 0.1 mol / L Ni(NO3)2 solution with a mass ratio of 1:5 between the second silicon support and the Ni(NO3)2 solution. After drying, it is subjected to a reduction reaction for 1 h in a H2 / Ar mixed gas with a volume ratio of 1:9 and at a temperature of 460°C to obtain the third silicon support. Step (4): Graphene layer is deposited on the surface of the third silicon carrier obtained in step (3) by chemical vapor deposition, 20 sccm CH4 and 100 sccm H2 are introduced, and growth is carried out at 1050℃ for 40 min to obtain the first graphene. Step (5): Immerse the first graphene obtained in step (4) in 0.8wt% PAMAM ethanol solution, the mass ratio of the first graphene to PAMAM ethanol solution is 1:7, stir and react at 85℃ for 6h, filter, and vacuum dry to obtain the modified conductive graphene.

[0038] Example 3 This example provides a modified conductive graphene, the preparation method of which includes the following steps: Step (1): Add aluminum-silicon alloy powder (30% Al by mass, 3μm particle size) to a 1.0mol / L NaOH solution, wherein the mass ratio of the aluminum-silicon alloy powder to the NaOH solution is 1:12, react at 90℃ for 2h, wash until neutral, and vacuum dry to obtain the first silicon support; Step (2): Under an argon atmosphere, the first silicon support obtained in step (1) with a mass ratio of 1:3 and magnesium powder are heated and reacted at 680°C for 3 hours; after the reaction is completed and cooled to room temperature, 1 mol / L HCl solution is added for acid washing for 40 minutes, and then vacuum dried to obtain the second silicon support. Step (3): The second silicon support obtained in step (2) is immersed in a 0.1 mol / L Ni(NO3)2 solution with a mass ratio of 1:5 between the second silicon support and the Ni(NO3)2 solution. After drying, it is subjected to a reduction reaction at 450°C for 1 h in a H2 / Ar mixed gas with a volume ratio of 1:9 to obtain the third silicon support. Step (4): Graphene layer is deposited on the surface of the third silicon carrier obtained in step (3) by chemical vapor deposition, 25 sccm CH4 and 120 sccm H2 are introduced, and growth is carried out at 1100℃ for 30 min to obtain the first graphene. Step (5): Immerse the first graphene obtained in step (4) in 0.8wt% PAMAM ethanol solution, the mass ratio of the first graphene to PAMAM ethanol solution is 1:7, stir and react at 90℃ for 5h, filter, and vacuum dry to obtain the modified conductive graphene.

[0039] Comparative Example 1 This example provides a modified conductive graphene and its preparation method, which differs from Example 1 only in that: (1) Step (2) was not performed.

[0040] The preparation method of the above-mentioned modified conductive graphene includes the following steps: This example provides a modified conductive graphene, the preparation method of which includes the following steps: Step (1): Add aluminum-silicon alloy powder (30% Al by mass, 3μm particle size) to a 1.0mol / L NaOH solution, wherein the mass ratio of the aluminum-silicon alloy powder to the NaOH solution is 1:12, react at 85℃ for 2.5h, wash until neutral, and vacuum dry to obtain the first silicon support; Step (2): The first silicon support obtained in step (1) is immersed in a 0.1 mol / L Ni(NO3)2 solution with a mass ratio of 1:5. After drying, it is subjected to a reduction reaction at 450°C for 1.5 h in a H2 / Ar mixed gas with a volume ratio of 1:9 to obtain the second silicon support. Step (3): Graphene layer is deposited on the surface of the second silicon carrier obtained in step (2) by chemical vapor deposition, 22 sccm CH4 and 115 sccm H2 are introduced, and growth is carried out at 1080℃ for 35 min to obtain the first graphene. Step (4): The first graphene obtained in step (3) is immersed in 0.8wt% PAMAM ethanol solution, the mass ratio of the first graphene to PAMAM ethanol solution is 1:7, and the reaction is carried out at 85℃ for 6h with stirring, filtered and vacuum dried to obtain the modified conductive graphene.

[0041] Comparative Example 2 This example provides a modified conductive graphene and its preparation method, which differs from Example 1 only in that: (1) Step (5) was not performed.

[0042] The preparation method of the above-mentioned modified conductive graphene includes the following steps: Step (1): Add aluminum-silicon alloy powder (30% Al by mass, 3μm particle size) to a 1.0mol / L NaOH solution, wherein the mass ratio of the aluminum-silicon alloy powder to the NaOH solution is 1:12, react at 85℃ for 2.5h, wash until neutral, and vacuum dry to obtain the first silicon support; Step (2): Under an argon atmosphere, the first silicon support obtained in step (1) with a mass ratio of 1:2 and magnesium powder are heated and reacted at 650°C for 4 hours; after the reaction is completed and cooled to room temperature, 1 mol / L HCl solution is added for acid washing for 40 minutes, and then vacuum dried to obtain the second silicon support. Step (3): The second silicon support obtained in step (2) is immersed in a 0.1 mol / L Ni(NO3)2 solution with a mass ratio of 1:5. After drying, it is subjected to a reduction reaction at 450°C for 1.5 h in a H2 / Ar mixed gas with a volume ratio of 1:9 to obtain the third silicon support. Step (4): Graphene layer is deposited on the surface of the third silicon carrier obtained in step (3) by chemical vapor deposition, 22 sccm CH4 and 115 sccm H2 are introduced, and growth is carried out at 1080℃ for 35 min to obtain the modified conductive graphene.

[0043] Test case This example demonstrates the application of the modified conductive graphene obtained in the above embodiments and comparative examples to the fabrication of bipolar plates for fuel cells, and tests its sheet resistivity and flexural strength. A commercially available conventional bipolar plate is used as a baseline control. The fabrication of the fuel cell bipolar plate includes the following process: 12 parts by weight of modified graphene, 24 parts by weight of polyethylene dioxythiophene, 12 parts by weight of epoxy resin, and 10 parts by weight of carbon nanotubes are added to 55 parts by weight of N-methylpyrrolidone solvent and ultrasonically dispersed at a power of 265 W for 45 min to obtain a slurry; the slurry is then coated onto a graphite substrate, pre-cured at 120°C for 1 h, and then hot-pressed at 182°C and 11 MPa for 2.5 h to form a 0.5 mm thick bipolar plate.

[0044] The test results are shown in Table 1.

[0045] Table 1 As shown in Table 1: 1) Compared with commercially available conventional products, the bipolar plates of fuel cells prepared using the modified conductive graphene provided in this embodiment of the invention have lower sheet resistance and higher bending strength, indicating that they have excellent electrical and mechanical properties, which can meet the needs of applications such as fuel cells and have broad application prospects.

[0046] 2) The test results of Comparative Examples 1-2 and Example 1 show that the synergistic effect of each step in the present invention, such as “step 2 - magnesium thermal reduction to prepare the second silicon support” and “step 5 - PAMAM grafting modification”, significantly improves the conductivity and compatibility of the modified conductive graphene. It can not only significantly reduce the surface resistance of the bipolar plate of the fuel cell, but also improve its mechanical properties and extend its service life.

[0047] Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0048] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing modified conductive graphene, characterized in that, Includes the following steps: Aluminum-silicon alloy powder was added to an alkaline solution for a first stirring reaction, followed by washing and drying to obtain the first silicon support. Under an inert gas atmosphere, the first silicon support and magnesium powder are heated and reacted, followed by acid washing and drying to obtain the second silicon support; The second silicon support was immersed in a nickel-containing solution, then dried and reduced to obtain the third silicon support; A graphene layer was deposited on the surface of the third silicon carrier using chemical vapor deposition to obtain the first graphene. The first graphene was immersed in a PAMAM ethanol solution for a second stirring reaction to obtain the modified conductive graphene.

2. The method for preparing modified conductive graphene according to claim 1, characterized in that, The steps of adding aluminum-silicon alloy powder to an alkaline solution for a first stirring reaction, followed by washing and drying to obtain the first silicon support include the following processes: The aluminum-silicon alloy powder was added to a NaOH solution with a concentration of 1~1.5 mol / L and reacted at 80~90℃ for 2~3 hours. After washing until neutral, the powder was dried under vacuum to obtain the first silicon support.

3. The method for preparing modified conductive graphene according to claim 2, characterized in that, The aluminum-silicon alloy powder contains 27% to 35% Al by mass, has a particle size of 2 to 5 μm, and has a mass ratio of 1:(10 to 15) between the aluminum-silicon alloy powder and the NaOH solution.

4. The method for preparing modified conductive graphene according to claim 1, characterized in that, The steps of heating and reacting the first silicon support and magnesium powder under an inert gas atmosphere, followed by acid washing and drying, to obtain the second silicon support include the following processes: Under an argon atmosphere, the first silicon support and the magnesium powder in a mass ratio of 1:(2~3) are heated at 600~680℃ for 3~5h. After the reaction is completed, 1mol / L HCl solution is added for acid washing for 30~45min, followed by vacuum drying to obtain the second silicon support.

5. The method for preparing modified conductive graphene according to claim 1, characterized in that, The steps of immersing the second silicon support in a nickel-containing solution, followed by drying and reduction, to obtain the third silicon support include the following processes: The second silicon support was immersed in a 0.1 mol / L Ni(NO3)2 solution, dried, and then reduced for 1 to 1.5 h in a H2 / Ar mixed gas with a volume ratio of 1:(8~9) at a temperature of 400~460°C to obtain the third silicon support.

6. The method for preparing modified conductive graphene according to claim 1, characterized in that, A graphene layer was deposited on the surface of the third silicon carrier using chemical vapor deposition to obtain the first graphene. Includes the following processes: The first graphene was obtained by introducing 20-25 sccm CH4 and 100-120 sccm H2 and growing at 1050-1100℃ for 30-40 min, followed by cooling to room temperature.

7. The method for preparing modified conductive graphene according to claim 1, characterized in that, The step of immersing the first graphene in a PAMAM ethanol solution for a second stirring reaction to obtain the second graphene includes the following process: The first graphene was immersed in a 0.5-1 wt% PAMAM ethanol solution, and the second stirring reaction was carried out at 80-90°C for 5-7 hours. After filtration and vacuum drying, the modified conductive graphene was obtained.

8. A modified conductive graphene, characterized in that, The modified conductive graphene is prepared by the method described in any one of claims 1 to 7.

9. The application of the modified conductive graphene according to claim 8 in the preparation of capacitors and fuel cells.

10. The application according to claim 9, characterized in that, The preparation of the bipolar plate of the fuel cell includes the following steps: 10-15 parts by weight of modified graphene, 20-25 parts by weight of polyethylene dioxythiophene, 10-15 parts by weight of epoxy resin, and 8-13 parts by weight of carbon nanotubes were added to 50-60 parts by weight of N-methylpyrrolidone solvent and ultrasonically dispersed. The ultrasonic power was 200-300W and the ultrasonic time was 30-60min to obtain a slurry. The slurry is coated onto a graphite substrate and pre-cured at 120-125°C for 1-1.5 hours, followed by hot pressing at 180-185°C and 10-12 MPa for 2-2.5 hours to form a 0.5 mm thick bipolar plate.

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