Special graphite plate for fuel cell and its preparation process

Abstract

This application discloses a special graphite plate for fuel cells and its preparation process, relating to the field of fuel cell technology. The raw materials, by weight, include 78-82 parts pre-expanded graphite, 2-3 parts carbon black, 6-8 parts graphene-modified mesophase carbon microspheres, 1.5-2.5 parts silicon carbide whiskers, 4-6 parts borosilicate-modified phenolic resin, 0.3-0.5 parts silane coupling agent, and 20-30 parts anhydrous ethanol. The pre-expanded graphite, carbon black, graphene-modified mesophase carbon microspheres, and silicon carbide whiskers are added to a high-speed mixer for dry mixing. Then, borosilicate-modified phenolic resin and silane coupling agent are added, and high-speed shear mixing continues. Anhydrous ethanol is added, and after mixing, the materials are dried and crushed into powder. The obtained powder is placed in a mold and pressed into shape. The sample is then cured by stepped heating and pressing, and after cooling, the special graphite plate for fuel cells is obtained. The graphite plate provided by this application has excellent surface conductivity and mechanical strength.

Description

Technical Field

[0001] This application relates to the field of fuel cell technology, and in particular to a special graphite plate for fuel cells and its preparation process. Background Technology

[0002] Hydrogen-powered proton exchange membrane fuel cell systems are a promising alternative to traditional energy supply equipment. They convert the chemical energy of hydrogen and oxygen into electrical energy through a chemical reaction, emitting only water and heat during the process and not releasing greenhouse gases that cause environmental problems. This makes them an environmentally friendly green energy conversion device. A fuel cell system includes key components such as a catalyst, bipolar plates, a proton exchange membrane, and a gas diffusion layer. The bipolar plates are a crucial component of the fuel cell system, connecting multiple individual cells and bearing clamping forces, dividing the reaction zone, transporting reactant gases while preventing their escape, collecting and conducting current, and transferring the water and heat generated in the reaction.

[0003] Based on the matrix material, bipolar plates can be mainly divided into three categories: metal bipolar plates, graphite bipolar plates, and graphite composite bipolar plates. Graphite composite bipolar plates are made primarily from organic polymer resins and carbon-based conductive fillers. The resin matrix enhances mechanical properties and binds the conductive fillers, while the conductive fillers, represented by graphite, form a conductive network within the composite material, enabling the composite graphite bipolar plate to conduct electricity and heat. Currently, graphite composite bipolar plates are mainly manufactured by uniformly mixing graphite powder and resin before molding. However, the insulating properties of the resin matrix significantly reduce the material's conductivity, and ordinary resins lack long-term stability under high temperature or acidic environments. This results in the composite bipolar plate's conductivity, airtightness, and durability failing to meet the stringent requirements of fuel cells. Summary of the Invention

[0004] To improve the mechanical strength and durability of special graphite plates for fuel cells, this application provides a special graphite plate for fuel cells and its preparation process.

[0005] This application provides a special graphite plate for fuel cells, which adopts the following technical solution: A special graphite plate for fuel cells, comprising, by weight, 78-82 parts pre-expanded graphite, 2-3 parts carbon black, 6-8 parts graphene-modified mesophase carbon microspheres, 1.5-2.5 parts silicon carbide whiskers, 4-6 parts borosilicate-modified phenolic resin, 0.3-0.5 parts silane coupling agent, and 20-30 parts anhydrous ethanol.

[0006] Preferably, the method for preparing the pre-expanded graphite includes the following steps: Using concentrated sulfuric acid as the electrolyte, natural flake graphite as the anode, and stainless steel as the cathode, the current density is 50-80 mA / g, and the oxidation time is 30-60 min. After oxidation, the graphite is washed with water until the pH is greater than 5, and then expanded in a muffle furnace at 900-1000℃ for 15-30 s to obtain expanded graphite. The expanded graphite is washed with water several times, then soaked in hydrochloric acid for 2-4 h, washed with water until neutral, and then vacuum dried for 6-8 h to obtain pre-expanded graphite.

[0007] Preferably, the preparation method of the graphene-modified mesophase carbon microspheres includes the following steps: S1. Graphene oxide is dissolved in quinoline solvent to prepare a mixed dispersion liquid. After ultrasonic dispersion for 1-2 hours, molten asphalt is added and ultrasonic dispersion is carried out for another 1-2 hours. The quinoline solvent is then separated by distillation to obtain graphene-modified asphalt. S2. Place the graphene-modified pitch in a reactor and thermally polymerize it at 380-420℃ for 1-3 hours under nitrogen protection. Then, place the product in an extractor and heat it under reflux for 8-10 hours using quinoline solvent as the extraction solvent. Stop the extraction and cool it. Then, separate the quinoline solvent by distillation, wash it several times with water, and vacuum dry it for 6-8 hours to obtain graphene-modified mesophase carbon microspheres.

[0008] Preferably, the mass ratio of graphene oxide, quinoline solvent, and asphalt is 0.005-0.01:1-2:1.

[0009] Preferably, the borosilicate modified phenolic resin is prepared from the following raw materials in parts by weight: 25-50 parts borosilicate resin powder, 0.75-1.5 parts phenyl silicone resin, and 14-28 parts ethanol.

[0010] Preferably, the phenyl silicone resin is prepared from the following raw materials in parts by weight: 1.2-2.4 parts hexamethyldisiloxane, 6.9-13.8 parts phenyltrimethoxysilane, 3.4-6.8 parts ethanol, 3-6 parts water, 1-2 parts glacial acetic acid, and 5.2-10.4 parts tetraethyl orthosilicate.

[0011] Preferably, the method for preparing the phenyl silicone resin includes the following steps: Mix 1.2-2.4 parts hexamethyldisiloxane, 6.9-13.8 parts phenyltrimethoxysilane, 3.4-6.8 parts ethanol, 3-6 parts water, and 1-2 parts glacial acetic acid thoroughly. Then, add 5.2-10.4 parts tetraethyl orthosilicate dropwise while stirring. After the addition is complete, slowly heat to 65-70°C and continue stirring for 6-8 hours. After the reaction is complete, remove the byproducts by rotary evaporation to obtain phenyl silicone resin.

[0012] Preferably, the preparation method of the borosilicate modified phenolic resin includes the following steps: 0.75-1.5 parts of phenyl silicone resin were added to 1.5-3 parts of ethanol and stirred to dissolve, yielding a phenyl silicone resin ethanol solution. 25-50 parts of boron phenolic resin powder were added to 12.5-25 parts of ethanol and heated to 50-60℃ and stirred to dissolve, yielding a boron phenolic resin ethanol solution. The phenyl silicone resin ethanol solution was added to the boron phenolic resin ethanol solution and stirred for 1-2 hours. After cooling to room temperature, the temperature was first raised to 80-90℃ and treated for 30-40 minutes; then raised to 130-140℃ and treated for 30-40 minutes; finally, the temperature was raised to 150-160℃ and treated for 30-40 minutes. After cooling, the silicon-boron modified phenolic resin was obtained.

[0013] This application provides a manufacturing process for a special graphite plate for fuel cells, which adopts the following technical solution: A process for preparing a special graphite plate for fuel cells includes the following steps: 78-82 parts of pre-expanded graphite, 2-3 parts of carbon black, 6-8 parts of graphene-modified mesophase carbon microspheres, and 1.5-2.5 parts of silicon carbide whiskers are added to a high-speed mixer and dry-mixed at 60-80℃ for 20-30 minutes. Then, 4-6 parts of borosilicate-modified phenolic resin and 0.3-0.5 parts of silane coupling agent are added, and high-speed shear mixing continues for 30-45 minutes. 20-30 parts of anhydrous ethanol are slowly added, and stirring continues for 15-20 minutes. After the mixture is fully mixed, the material is dried in a vacuum drying oven and crushed into powder. The powder is placed in a mold and pressed at 25-30℃ and a molding pressure of 10-11 MPa for 3-4 minutes to form the desired shape. The sample is then cured by step-heating pressing, and after cooling, a special graphite plate for fuel cells is obtained.

[0014] Preferably, the stepped temperature curing process is performed as follows: first from room temperature to 800℃ at a heating rate of 5℃ / min; then from 800℃ to 1200℃ at a heating rate of 3℃ / min; and finally from 1200℃ to 3000℃ at a heating rate of 2℃ / min.

[0015] In summary, this application includes at least one of the following beneficial technical effects: 1. This application uses pre-expanded graphite as the main conductive framework. After electrochemical intercalation and high-temperature expansion treatment, the interlayer spacing is significantly increased. The worm-like structure gives it a high specific surface area and excellent compression resilience. It can achieve effective intergranular interlocking under low molding pressure. At the same time, its high graphitization ensures the high electrical conductivity of the graphite plate.

[0016] 2. This application involves ultrasonically dispersing and thermally polymerizing graphene oxide and pitch in a quinoline solvent, with graphene sheets uniformly embedded in the carbon skeleton of mesophase carbon microspheres. This core-shell or embedded structure allows the mesophase carbon microspheres to combine the easy graphitization properties of mesophase pitch with the high electrical and thermal conductivity advantages of graphene, which can significantly improve the electrical conductivity and durability of graphite plates.

[0017] 3. The borosilicate-modified phenolic resin used in this application is synergistically modified by introducing boron and organosilicon resin. The BO bonds in the borosilicate resin have high bond energy and can exist stably at high temperatures. The phenyl silicone resin forms Si-OC and Si-C bonds after high-temperature pyrolysis, transforming into ceramic phase residues. These ceramic phases not only fill some pores, improving the density and airtightness of the material, but also endow the graphite plate with excellent acid corrosion resistance and extend the service life of the graphite plate. Detailed Implementation

[0018] The present application will be further described in detail below with reference to the embodiments.

[0019] The chemical reagents used in the preparation examples, embodiments, and comparative examples provided in this invention are all commercially available products. Boron phenolic resin, purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.; Phenolic resin, purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd., product number: PC80091; Natural flake graphite, purchased from Shanghai Jiadeer Chemical Technology Co., Ltd. The asphalt was purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd. Preparation Example 1: Preparation of Pre-expanded Graphite Preparation Example 1.1 Using concentrated sulfuric acid as the electrolyte, natural flake graphite as the anode, and stainless steel as the cathode, the current density was 50 mA / g, and the oxidation time was 30 min. After oxidation, the graphite was washed with water until the pH was greater than 5, and then expanded in a muffle furnace at 900℃ for 30 s to obtain expanded graphite. The expanded graphite was washed with water three times, then soaked in hydrochloric acid for 2 h, washed with water until neutral, and then vacuum dried at 60℃ for 6 h to obtain pre-expanded graphite.

[0020] Preparation Example 1.2 Using concentrated sulfuric acid as the electrolyte, natural flake graphite as the anode, and stainless steel as the cathode, the current density was 80 mA / g, and the oxidation time was 60 min. After oxidation, the graphite was washed with water until the pH was greater than 5, and then expanded in a muffle furnace at 1000℃ for 15 s to obtain expanded graphite. The expanded graphite was washed with water 5 times, then soaked in hydrochloric acid for 4 h, washed with water until neutral, and then vacuum dried at 70℃ for 8 h to obtain pre-expanded graphite.

[0021] Preparation Example 2: Preparation of Graphene-Modified Mesophase Carbon Microspheres Preparation Example 2.1 S1. Dissolve 0.5g of graphene oxide in 100g of quinoline solvent to prepare a mixed dispersion liquid. After ultrasonic dispersion for 1h, add 100g of melted asphalt and ultrasonically disperse for another 1h. Then, separate the quinoline solvent by distillation to obtain graphene-modified asphalt. S2. The graphene-modified pitch was placed in a reactor and thermally polymerized at 380°C for 1 hour under nitrogen protection. The product was then placed in an extractor and heated under reflux for 8 hours using quinoline solvent. The extraction was stopped and the mixture was cooled. The quinoline solvent was then separated by distillation. After washing with water three times, the mixture was vacuum dried at 60°C for 6 hours to obtain graphene-modified mesophase carbon microspheres.

[0022] Preparation Example 2.2 S1. Dissolve 1g of graphene oxide in 200g of quinoline solvent to prepare a mixed dispersion liquid. After ultrasonic dispersion for 2h, add 100g of melted asphalt and ultrasonic dispersion for another 2h. Then, separate the quinoline solvent by distillation to obtain graphene-modified asphalt. S2. The graphene-modified pitch was placed in a reactor and thermally polymerized at 420°C for 3 hours under nitrogen protection. The product was then placed in an extractor and heated under reflux for 10 hours using quinoline solvent. The extraction was stopped and the mixture was cooled. The quinoline solvent was then separated by distillation. After washing with water four times, the mixture was vacuum dried at 70°C for 8 hours to obtain graphene-modified mesophase carbon microspheres.

[0023] Preparation Example 3: Preparation of Borosilicate Modified Phenolic Resin Preparation Example 3.1 T1. Mix 1.2g hexamethyldisiloxane, 6.9g phenyltrimethoxysilane, 3.4g ethanol, 3g water and 1g glacial acetic acid evenly, and then add 5.2g tetraethyl orthosilicate dropwise under stirring. After the addition is complete, slowly heat to 65℃ and continue stirring for 6 hours. After the reaction is completed, remove the byproducts by rotary evaporation to obtain phenyl silicone resin. T2. Add 0.75g of phenyl silicone resin to 1.5g of ethanol and stir to dissolve, obtaining a phenyl silicone resin ethanol solution; add 25g of boron phenolic resin powder to 12.5g of ethanol, heat to 50℃ and stir to dissolve, obtaining a boron phenolic resin ethanol solution; add the phenyl silicone resin ethanol solution to the boron phenolic resin ethanol solution, stir for 1h, cool to room temperature, then first heat to 80℃ and treat for 30min; then heat to 130℃ and treat for 30min; finally heat to 150℃ and treat for 30min; after cooling, the silicon-boron modified phenolic resin is obtained.

[0024] Preparation Example 3.2 T1. Mix 2.4g hexamethyldisiloxane, 13.8g phenyltrimethoxysilane, 6.8g ethanol, 6g water and 2g glacial acetic acid evenly, and then add 10.4g tetraethyl orthosilicate dropwise under stirring. After the addition is complete, slowly heat to 70°C and continue stirring for 8 hours. After the reaction is completed, remove the byproducts by rotary evaporation to obtain phenyl silicone resin. T2. Add 1.5g of phenyl silicone resin to 3g of ethanol and stir to dissolve, obtaining a phenyl silicone resin ethanol solution; add 50g of boron phenolic resin powder to 25g of ethanol, heat to 60℃ and stir to dissolve, obtaining a boron phenolic resin ethanol solution; add the phenyl silicone resin ethanol solution to the boron phenolic resin ethanol solution, stir for 2 hours, cool to room temperature, then first heat to 90℃ and treat for 40 minutes; then heat to 140℃ and treat for 40 minutes; finally heat to 160℃ and treat for 40 minutes; after cooling, the silicon-boron modified phenolic resin is obtained.

[0025] Example 1 78g of pre-expanded graphite prepared in Preparation Example 1.1, 2g of carbon black, 6g of graphene-modified mesophase carbon microspheres prepared in Preparation Example 2.1, and 1.5g of silicon carbide whiskers were added to a high-speed mixer and dry-mixed at 60°C for 20 min. Then, 4g of borosilicate-modified phenolic resin prepared in Preparation Example 3.1 and 0.3g of silane coupling agent were added, and high-speed shear mixing continued for 30 min. 20g of anhydrous ethanol was slowly added, and stirring continued for 15 min. After mixing, the material was placed in a vacuum drying oven to dry and then crushed into powder. The obtained powder was placed in a mold and pressed into shape at 25°C and a molding pressure of 10MPa for 3 minutes. The sample was then cured by step heating: first from room temperature to 800°C at a heating rate of 5°C / min; then from 800°C to 1200°C at a heating rate of 3°C / min; and finally from 1200°C to 3000°C at a heating rate of 2°C / min. After cooling, a special graphite plate for fuel cells was obtained. In this embodiment, the silane coupling agents used were KH-550 and KH-560 in a mass ratio of 1:1.

[0026] Example 2 80g of pre-expanded graphite prepared in Preparation Example 1.1, 2.5g of carbon black, 7g of graphene-modified mesophase carbon microspheres prepared in Preparation Example 2.1, and 1.5g of silicon carbide whiskers were added to a high-speed mixer and dry-mixed at 60°C for 20 min. Then, 5g of borosilicate-modified phenolic resin prepared in Preparation Example 3.1 and 0.4g of silane coupling agent were added, and high-speed shear mixing continued for 30 min. 25g of anhydrous ethanol was slowly added, and stirring continued for 15 min. After mixing, the material was placed in a vacuum drying oven to dry and then crushed into powder. The prepared powder was placed in a mold and pressed into shape at 25°C and a molding pressure of 10 MPa for 3 minutes. The sample was then cured by step heating: first from room temperature to 800°C at a heating rate of 5°C / min; then from 800°C to 1200°C at a heating rate of 3°C / min; and finally from 1200°C to 3000°C at a heating rate of 2°C / min. After cooling, a special graphite plate for fuel cells was obtained. In this embodiment, the silane coupling agents used were KH-550 and KH-560 in a mass ratio of 1:1.

[0027] Example 3 82g of pre-expanded graphite prepared in Preparation Example 1.1, 3g of carbon black, 8g of graphene-modified mesophase carbon microspheres prepared in Preparation Example 2.1, and 2.5g of silicon carbide whiskers were added to a high-speed mixer and dry-mixed at 60°C for 20 min. Then, 6g of borosilicate-modified phenolic resin prepared in Preparation Example 3.1 and 0.5g of silane coupling agent were added, and high-speed shear mixing continued for 30 min. 30g of anhydrous ethanol was slowly added, and stirring continued for 15 min. After mixing, the material was placed in a vacuum drying oven to dry and then crushed into powder. The obtained powder was placed in a mold and pressed into shape at 25°C and a molding pressure of 10MPa for 3 minutes. The sample was then cured by step heating: first from room temperature to 800°C at a heating rate of 5°C / min; then from 800°C to 1200°C at a heating rate of 3°C / min; and finally from 1200°C to 3000°C at a heating rate of 2°C / min. After cooling, a special graphite plate for fuel cells was obtained. In this embodiment, the silane coupling agents used were KH-550 and KH-560 in a mass ratio of 1:1.

[0028] Example 4 78g of pre-expanded graphite prepared in Preparation Example 1.1, 2g of carbon black, 6g of graphene-modified mesophase carbon microspheres prepared in Preparation Example 2.1, and 1.5g of silicon carbide whiskers were added to a high-speed mixer and dry-mixed at 80°C for 30 min. Then, 4g of borosilicate-modified phenolic resin prepared in Preparation Example 3.1 and 0.3g of silane coupling agent were added, and high-speed shear mixing continued for 40 min. 20g of anhydrous ethanol was slowly added, and stirring continued for 20 min. After mixing, the material was placed in a vacuum drying oven to dry and then crushed into powder. The resulting... The powder was placed into a mold and pressed into shape at 30°C and a molding pressure of 10.5 MPa for 4 minutes. The sample was then cured by step heating: first from room temperature to 800°C at a heating rate of 5°C / min; then from 800°C to 1200°C at a heating rate of 3°C / min; and finally from 1200°C to 3000°C at a heating rate of 2°C / min. After cooling, a special graphite plate for fuel cells was obtained. In this embodiment, the silane coupling agents used were KH-550 and KH-560 in a mass ratio of 1:1.

[0029] Example 5 78g of pre-expanded graphite prepared in Preparation Example 1.2, 2g of carbon black, 6g of graphene-modified mesophase carbon microspheres prepared in Preparation Example 2.2, and 1.5g of silicon carbide whiskers were added to a high-speed mixer and dry-mixed at 60°C for 20 min. Then, 4g of borosilicate-modified phenolic resin prepared in Preparation Example 3.2 and 0.3g of silane coupling agent were added, and high-speed shear mixing continued for 30 min. 20g of anhydrous ethanol was slowly added, and stirring continued for 15 min. After mixing, the material was placed in a vacuum drying oven to dry and then crushed into powder. The obtained powder was placed in a mold and pressed into shape at 25°C and a molding pressure of 10MPa for 3 minutes. The sample was then cured by step heating: first from room temperature to 800°C at a heating rate of 5°C / min; then from 800°C to 1200°C at a heating rate of 3°C / min; and finally from 1200°C to 3000°C at a heating rate of 2°C / min. After cooling, a special graphite plate for fuel cells was obtained. In this embodiment, the silane coupling agents used were KH-550 and KH-560 in a mass ratio of 1:1.

[0030] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that natural flake graphite was used in Comparative Example 1 instead of the pre-expanded graphite prepared in Preparation Example 1.1.

[0031] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that no graphene-modified mesophase carbon microspheres were added in Comparative Example 2.

[0032] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that ordinary phenolic resin is used in Comparative Example 3 instead of the borosilicate modified phenolic resin prepared in Preparation Example 3.1.

[0033] Performance testing The surface resistivity of the graphite composite plate was tested according to the test method in GB / T20042.6-2024 "Proton Exchange Membrane Fuel Cells - Part 6: Test Methods for Bipolar Plate Characteristics". The test results are shown in Table 1.

[0034] The bending strength of the graphite composite plate was tested according to the test method in GB / T20042.6-2024 "Proton Exchange Membrane Fuel Cells - Part 6: Test Methods for Bipolar Plate Characteristics". The test results are shown in Table 1.

[0035] The specific test results are as follows: Table 1 Performance Test Results

[0036] As can be seen from the test results in Table 1, the special graphite plate for fuel cells provided in this embodiment has better surface resistivity and compressive strength than the comparative example.

[0037] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A special graphite plate for fuel cells, characterized in that: The raw materials, by weight, include 78-82 parts pre-expanded graphite, 2-3 parts carbon black, 6-8 parts graphene-modified mesophase carbon microspheres, 1.5-2.5 parts silicon carbide whiskers, 4-6 parts borosilicate-modified phenolic resin, 0.3-0.5 parts silane coupling agent, and 20-30 parts anhydrous ethanol. The method for preparing the pre-expanded graphite includes the following steps: Using concentrated sulfuric acid as the electrolyte, natural flake graphite as the anode, and stainless steel as the cathode, the current density is 50-80 mA / g, and the oxidation time is 30-60 min. After oxidation, the graphite is washed with water until the pH is greater than 5, and then expanded in a muffle furnace at 900-1000℃ for 15-30 s to obtain expanded graphite. The expanded graphite is washed with water several times, then soaked in hydrochloric acid for 2-4 h, washed with water until neutral, and then vacuum dried for 6-8 h to obtain pre-expanded graphite. The preparation method of the graphene-modified mesophase carbon microspheres includes the following steps: S1. Graphene oxide is dissolved in quinoline solvent to prepare a mixed dispersion liquid. After ultrasonic dispersion for 1-2 hours, molten asphalt is added and ultrasonic dispersion is carried out for another 1-2 hours. The quinoline solvent is then separated by distillation to obtain graphene-modified asphalt. S2. Place the graphene-modified pitch in a reactor and thermally polymerize it at 380-420℃ for 1-3 hours under nitrogen protection. Then, place the product in an extractor and heat it under reflux for 8-10 hours using quinoline solvent as the extraction solvent. Stop the extraction and cool it. Then, separate the quinoline solvent by distillation, wash it several times with water, and vacuum dry it for 6-8 hours to obtain graphene-modified mesophase carbon microspheres.

2. The special graphite plate for fuel cells according to claim 1, characterized in that: The mass ratio of graphene oxide, quinoline solvent, and asphalt is 0.005-0.01:1-2:

1.

3. The special graphite plate for fuel cells according to claim 1, characterized in that: The borosilicate-modified phenolic resin is prepared from the following raw materials in parts by weight: 25-50 parts borosilicate resin powder, 0.75-1.5 parts phenyl silicone resin, and 14-28 parts ethanol.

4. A special graphite plate for fuel cells according to claim 3, characterized in that: The phenyl silicone resin is prepared from the following raw materials in parts by weight: 1.2-2.4 parts hexamethyldisiloxane, 6.9-13.8 parts phenyltrimethoxysilane, 3.4-6.8 parts ethanol, 3-6 parts water, 1-2 parts glacial acetic acid, and 5.2-10.4 parts tetraethyl orthosilicate.

5. A special graphite plate for fuel cells according to claim 4, characterized in that: The preparation method of the phenyl silicone resin includes the following steps: Mix 1.2-2.4 parts hexamethyldisiloxane, 6.9-13.8 parts phenyltrimethoxysilane, 3.4-6.8 parts ethanol, 3-6 parts water, and 1-2 parts glacial acetic acid thoroughly. Then, add 5.2-10.4 parts tetraethyl orthosilicate dropwise while stirring. After the addition is complete, slowly heat to 65-70°C and continue stirring for 6-8 hours. After the reaction is complete, remove the byproducts by rotary evaporation to obtain phenyl silicone resin.

6. A special graphite plate for fuel cells according to claim 3, characterized in that: The preparation method of the borosilicate modified phenolic resin includes the following steps: 0.75-1.5 parts of phenyl silicone resin were added to 1.5-3 parts of ethanol and stirred to dissolve, yielding a phenyl silicone resin ethanol solution. 25-50 parts of boron phenolic resin powder were added to 12.5-25 parts of ethanol and heated to 50-60℃ and stirred to dissolve, yielding a boron phenolic resin ethanol solution. The phenyl silicone resin ethanol solution was added to the boron phenolic resin ethanol solution and stirred for 1-2 hours. After cooling to room temperature, the temperature was first raised to 80-90℃ and treated for 30-40 minutes; then raised to 130-140℃ and treated for 30-40 minutes; finally, the temperature was raised to 150-160℃ and treated for 30-40 minutes. After cooling, the silicon-boron modified phenolic resin was obtained.

7. The preparation process of a special graphite plate for fuel cells according to any one of claims 1-6, characterized in that: Includes the following steps: 78-82 parts of pre-expanded graphite, 2-3 parts of carbon black, 6-8 parts of graphene-modified mesophase carbon microspheres, and 1.5-2.5 parts of silicon carbide whiskers are added to a high-speed mixer and dry-mixed at 60-80℃ for 20-30 minutes. Then, 4-6 parts of borosilicate-modified phenolic resin and 0.3-0.5 parts of silane coupling agent are added, and high-speed shear mixing continues for 30-45 minutes. 20-30 parts of anhydrous ethanol are slowly added, and stirring continues for 15-20 minutes. After the mixture is fully mixed, the material is dried in a vacuum drying oven and crushed into powder. The powder is placed in a mold and pressed at 25-30℃ and a molding pressure of 10-11 MPa for 3-4 minutes to form the desired shape. The sample is then cured by step-heating pressing, and after cooling, a special graphite plate for fuel cells is obtained.

8. The preparation process of a special graphite plate for fuel cells according to claim 7, characterized in that: The stepped temperature curing process is as follows: first, from room temperature to 800℃, the temperature rises at a rate of 5℃ / min; then from 800℃ to 1200℃, the temperature rises at a rate of 3℃ / min; and finally from 1200℃ to 3000℃, the temperature rises at a rate of 2℃ / min.

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