Preparation method of graphite plate and graphite plate

Abstract

The application discloses a preparation method of a graphite polar plate and the graphite polar plate. The method comprises the following steps: placing a graphite substrate in a resin solution for impregnation treatment, and solidifying to obtain an intermediate; and preparing a conductive coating on at least one side of the intermediate to obtain the graphite polar plate. By placing the graphite substrate in the resin solution for impregnation treatment, small pores and defects on the graphite substrate are filled, so that an effective barrier is formed to prevent electrolyte or other chemical substances from penetrating into the substrate. Furthermore, the formation of the conductive coating can further seal the unsealed blind holes and through holes of the resin solution, i.e. fill the large cracks of the through holes, so that the sealing performance of the graphite polar plate can be improved. Moreover, the graphite substrate itself has excellent conductivity, and the formation of the conductive coating will not affect the conductivity of the graphite substrate, so that the conductivity of the graphite polar plate can be ensured. Therefore, the graphite polar plate with good sealing performance can be obtained by using the preparation method.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, and specifically relates to a method for preparing a graphite electrode plate and the graphite electrode plate itself. Background Technology

[0002] A proton exchange membrane fuel cell (PEMFC) is a novel type of fuel cell composed of multiple cells connected in series. Each cell includes an anode plate, a membrane electrode assembly (MEA), and a cathode plate, with the MEA sandwiched between the anode and cathode plates. Both the anode and cathode plates are referred to as electrodes, and each electrode has a manifold orifice region, a distribution region, and a flow field region. The flow field region is where gas enters the membrane electrode and participates in the redox reaction.

[0003] The electrode plate can be made of metal, graphite, or composite materials. When graphite is chosen as the electrode plate material, low-density flexible graphite sheets are generally molded in one step, forming a flow field during the molding process, followed by resin impregnation, and finally heating and curing. However, during the manufacturing process, due to the material properties of flexible graphite itself, pores are easily generated, allowing fuel gas and oxidant gas to permeate each other, affecting the sealing performance of the graphite electrode plate. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one object of this invention is to provide a method for preparing a graphite electrode plate and the graphite electrode plate itself. Using the preparation method provided in this application, a graphite electrode plate with good sealing performance can be obtained.

[0005] In a first aspect, the present invention provides a method for preparing a graphite electrode plate. According to an embodiment of the present invention, the method includes: preparing a graphite substrate; placing the graphite substrate in a resin solution for impregnation treatment and curing to obtain an intermediate; and preparing a conductive coating on the surface of the intermediate to obtain a graphite electrode plate.

[0006] According to the method for preparing graphite electrode plates according to the above embodiments of the present invention, a graphite substrate is immersed in a resin solution. The resin adheres tightly to the surface of the graphite substrate, filling the micropores and defects on the graphite substrate, thereby forming an effective barrier to prevent electrolytes or other chemical substances from penetrating into the matrix, thus obtaining an intermediate. A conductive coating is then prepared on the surface of the intermediate, covering the surface of the barrier formed by the resin solution. Therefore, the conductive coating can further seal unsealed blind holes and through holes in the resin solution, i.e., fill large cracks in through holes, thereby improving the sealing performance of the graphite electrode plate. Furthermore, the graphite substrate itself has excellent conductivity; the formation of the conductive coating does not affect the conductivity of the graphite substrate, thus ensuring the conductivity of the graphite electrode plate. Therefore, the preparation method provided in this application can yield a graphite electrode plate with good sealing performance.

[0007] In addition, the preparation method according to the above embodiments of the present invention may also have the following additional technical features:

[0008] In some embodiments of the present invention, the step of preparing the conductive coating includes: mixing a thermosetting resin, filler, binder, and solvent to obtain a conductive slurry; and coating the conductive slurry onto the surface of the intermediate to obtain a conductive coating. This results in a graphite electrode plate with good sealing performance.

[0009] In some embodiments of the present invention, the viscosity of the conductive paste is greater than the viscosity of the resin solution. This results in a graphite electrode plate with better sealing performance.

[0010] In some embodiments of the present invention, the viscosity of the resin solution is less than 50 cP. This allows it to penetrate into the minute pores and defects on the surface of the graphite electrode substrate, improving the overall sealing performance of the graphite electrode.

[0011] In some embodiments of the present invention, the viscosity of the conductive paste is 50 cP-200 cP. This compensates for the inability of resin coatings to achieve complete sealing, ensuring that through-holes are effectively closed.

[0012] In some embodiments of the present invention, the thickness of the graphite substrate is 0.05 mm to 0.5 mm. This improves the stability of the battery.

[0013] In some embodiments of the present invention, the resin solution includes at least one selected from polyacrylonitrile, polyvinyl alcohol, polyvinylidene fluoride, and polyphenylene ether. This allows it to penetrate into the minute pores and defects on the surface of the graphite electrode substrate, improving the overall sealing performance of the graphite electrode.

[0014] In some embodiments of the present invention, the thickness of the conductive coating is greater than or equal to 25 μm. This ensures the smoothness and consistency of the coating surface, improving the stability of its conductivity.

[0015] In some embodiments of the present invention, the thermosetting resin includes at least one selected from epoxy resin, polyurethane resin, and acrylate resin. This ensures the mechanical properties of the conductive coating, thereby improving the mechanical properties of the graphite electrode.

[0016] In some embodiments of the present invention, the filler includes at least one selected from graphite, carbon nanotubes, copper, nickel, and silver. This results in a conductive coating with conductive properties, which in turn improves the conductivity of the graphite electrode.

[0017] In a second aspect, the present invention provides a graphite electrode plate, which, according to an embodiment of the invention, is prepared by the method described above. Therefore, the graphite electrode plate has good sealing performance.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0020] Figure 1 A schematic diagram showing different pore sizes in the cross-section of a graphite electrode plate according to an embodiment of this application is displayed. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0022] In a first aspect, the present invention provides a graphite electrode plate, comprising, according to an embodiment of the invention:

[0023] S1. Prepare a graphite substrate.

[0024] In this step, a graphite substrate containing a flow field can be obtained. Specifically, the graphite substrate is prepared by methods such as etching and molding.

[0025] S2. The graphite substrate is immersed in a resin solution and cured to obtain an intermediate.

[0026] In this step, an intermediate is obtained by immersing a graphite substrate in a resin solution and then curing it. The immersion process allows the resin solution to fully penetrate the tiny pores and defects of the graphite substrate, achieving a complete seal. After curing, a resin barrier forms on the surface of the graphite substrate. This continuous and defect-free barrier effectively prevents gas and electrolyte leakage, improving the battery's sealing performance.

[0027] It should be noted that the curing method is not special; for example, it can be high-temperature curing or ultraviolet curing. Those skilled in the art can choose flexibly according to their needs.

[0028] According to some specific embodiments of the present invention, the viscosity of the resin solution is less than 50 cP, for example, it can be 10 cP, 20 cP, 30 cP, 40 cP, 48 cP, etc. By limiting the viscosity of the resin solution within the above range, on the one hand, it has good fluidity, which can ensure the uniform distribution of the resin solution on the surface of the graphite electrode substrate, and on the other hand, it allows the resin solution to penetrate into the micropores and defects on the surface of the graphite electrode substrate, sealing the blind holes on the graphite substrate, thereby improving the overall sealing performance of the graphite electrode.

[0029] As an example, the resin solution includes, but is not limited to, at least one of polyacrylonitrile, polyvinyl alcohol, polyvinylidene fluoride, and polyphenylene ether.

[0030] According to some specific embodiments of the present invention, the graphite substrate is made of flexible graphite. Flexible graphite is chosen as the material for the graphite substrate because, on the one hand, it possesses excellent electrical and thermal conductivity, enabling it to effectively transfer current and heat, thus ensuring the efficient operation of the fuel cell. On the other hand, flexible graphite can resist the erosion of various chemical substances, thereby ensuring the long-term stability and reliability of the graphite electrode plates.

[0031] According to some specific embodiments of the present invention, the thickness of the graphite substrate is 0.05mm-0.5mm. For example, it can be 0.05mm, 0.1mm, 0.3mm, 0.5mm, etc. By limiting the thickness of the graphite substrate within the above range, it is beneficial to the uniform distribution and rapid conduction of heat, prevent local overheating or thermal stress concentration, thereby improving the stability of the battery.

[0032] S3. Prepare a conductive coating on the surface of the intermediate to obtain a graphite electrode plate.

[0033] In this step, a conductive coating is prepared on the surface of the intermediate to obtain a graphite electrode plate. The conductive coating can further seal the blind holes and through holes that are not sealed by the resin solution, thereby improving the sealing performance of the graphite electrode plate. Moreover, the graphite substrate itself has excellent conductivity, and the formation of the conductive coating does not affect the conductivity of the graphite substrate, thus ensuring the conductivity of the graphite electrode plate.

[0034] It should be noted that the reference Figure 1 As shown, a through hole refers to a hole that passes from one side of a graphite electrode to the other, while a blind hole refers to a hole that enters the interior of a graphite electrode from only one side but does not penetrate the entire thickness of the plate.

[0035] According to some specific embodiments of the present invention, the thickness of the conductive coating is greater than or equal to 25 μm. For example, it can be 25 μm, 50 μm, 100 μm, etc. By limiting the thickness of the conductive coating within the above range, on the one hand, it can ensure that the conductive particles or materials inside the conductive coating are uniformly distributed, thereby providing a stable and efficient conductive channel, which helps to reduce current loss during transmission and improve battery performance. On the other hand, it can ensure the smoothness and consistency of the coating surface, improving the stability of conductivity.

[0036] According to some specific embodiments of the present invention, step S3 further includes steps S31 and S32:

[0037] S31. Mix thermosetting resin, filler, binder and solvent to obtain conductive paste.

[0038] In this step, a conductive paste is obtained by mixing thermosetting resin, filler, binder, and solvent. By combining the thermosetting resin and filler, a conductive coating with both good mechanical and electrical properties can be prepared. The thermosetting resin possesses good insulation properties, chemical stability, and mechanical strength, providing necessary support and protection for the conductive coating. The filler has high conductivity and can form a conductive network within the coating, thus making the entire coating conductive.

[0039] It should be noted that there are no particular limitations on the types of thermosetting resins, fillers, binders, and solvents. Those skilled in the art can make flexible selections as needed. In one specific embodiment of the present invention, the thermosetting resin includes, but is not limited to, at least one of epoxy resin, polyurethane resin, and acrylate resin. The filler includes, but is not limited to, at least one of graphite, carbon nanotubes, copper, nickel, and silver.

[0040] According to some specific embodiments of the present invention, the viscosity of the conductive paste is greater than the viscosity of the resin solution. The higher viscosity of the conductive paste allows for greater pressure to be applied when it is coated onto the surface of the intermediate, resulting in a tighter adhesion of the conductive coating to the graphite substrate surface and around the vias. This pressure compensates for the inability of the resin solution to achieve a complete seal, ensuring effective closure of the vias. This improves the sealing performance of the graphite electrode.

[0041] According to some specific embodiments of the present invention, the viscosity of the conductive paste is 50 cP-200 cP. For example, it can be 50 cP, 100 cP, 150 cP, 200 cP, etc. By limiting the viscosity of the conductive paste within the above range, the conductive paste has good fluidity, which ensures uniform coating on the surface of the intermediate. When the conductive paste is coated on the surface of the intermediate, greater pressure can be applied, making the coating adhere more tightly to the surface of the graphite substrate and around the through holes. This pressure can compensate for the complete sealing that the resin solution cannot achieve, ensuring that the through holes are effectively closed. Therefore, the sealing performance of the graphite electrode can be improved.

[0042] S32. The conductive paste is coated on the surface of the intermediate to obtain a conductive coating.

[0043] In this step, a conductive paste is applied to the surface of the intermediate using a coating method, forming a conductive coating on the surface of the intermediate. Thus, through the coating process, the conductive paste is uniformly coated on the surface of the intermediate. After curing or drying, the filler forms a continuous conductive network on the surface of the intermediate, which helps to improve the conductivity of the graphite electrode. Furthermore, the conductive paste can seal through-holes that the resin solution cannot seal, further improving the sealing performance of the graphite electrode.

[0044] It should be noted that there are no special limitations on the coating parameters, and those skilled in the art can make flexible selections as needed.

[0045] In a second aspect, the present invention provides a graphite electrode plate, which, according to an embodiment of the invention, is prepared using the method described above. By impregnating a graphite substrate in a resin solution, an intermediate is obtained. The resin adheres tightly to the surface of the graphite substrate, filling micropores and defects in the substrate, thereby forming an effective barrier to prevent electrolytes or other chemical substances from penetrating into the substrate. A conductive coating is then applied to at least one side of the intermediate by coating, covering the surface of the resin. This conductive coating further seals any unsealed blind holes and through holes in the resin, thereby further improving the sealing performance of the graphite electrode plate. Furthermore, the graphite substrate itself has excellent conductivity; the formation of the conductive coating does not affect the conductivity of the graphite substrate, thus ensuring the conductivity of the graphite electrode plate. Therefore, the graphite electrode plate provided by this application has both good sealing performance and good conductivity.

[0046] The present disclosure will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the disclosure. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0047] Example 1

[0048] 1) Prepare a graphite substrate by roll forming a graphite blank and etching the flow field region to obtain a graphite substrate.

[0049] 2) The graphite substrate was immersed in a polyacrylonitrile solution. During immersion under negative pressure, the vacuum level was 1 Pa, and the immersion time was 60 min. During immersion under normal pressure, the immersion time was 30 min. The immersed substrate was then vacuum-dried and cured to obtain a graphite substrate with a resin coating on its surface. During the vacuum drying and curing process, the vacuum level was 10 Pa, the drying temperature was 170℃, and the curing time was 30 min. The thickness of the graphite substrate was 0.05 mm, and the viscosity of the polyacrylonitrile solution was 30 cP.

[0050] 3) Epoxy resin, graphite, binder, and solvent are mixed to obtain a conductive slurry. The conductive slurry is then coated onto the outer surface of the intermediate. After curing and drying, a conductive coating is obtained, which is the graphite electrode plate. The thickness of the conductive coating is 25 μm, and the viscosity of the conductive slurry is 50 cP.

[0051] Example 2

[0052] 1) Prepare a graphite substrate by roll forming a graphite blank and etching the flow field region to obtain a graphite substrate.

[0053] 2) The graphite substrate was immersed in a polyacrylonitrile solution. During immersion under negative pressure, a vacuum of 1 Pa was applied for 60 minutes. During immersion under normal pressure, the immersion time was 30 minutes. The immersed substrate was then vacuum-dried and cured to obtain a graphite substrate with a resin coating on its surface. During the vacuum drying and curing process, the vacuum level was 10 Pa, the drying temperature was 170℃, and the curing time was 30 minutes. The thickness of the graphite substrate was 0.05 mm, the thickness of the resin coating was 5 μm, and the viscosity of the resin coating was 30 cP.

[0054] 3) Epoxy resin, graphite, binder, and solvent are mixed to obtain a conductive slurry. The conductive slurry is then coated onto the outer surface of the resin coating. After curing and drying, a conductive coating is obtained, which is the graphite electrode plate. The thickness of the conductive coating is 25 μm, and the viscosity of the conductive coating is 100 cP.

[0055] Example 3

[0056] 1) Prepare a graphite substrate by roll forming a graphite blank and etching the flow field region to obtain a graphite substrate.

[0057] 2) The graphite substrate was immersed in a polyacrylonitrile solution. During immersion under negative pressure, the vacuum level was 1 Pa, and the immersion time was 60 min. During immersion under normal pressure, the immersion time was 30 min. The immersed substrate was then vacuum-dried and cured to obtain a graphite substrate with a resin coating on its surface. During the vacuum drying and curing process, the vacuum level was 10 Pa, the drying temperature was 170℃, and the curing time was 30 min. The thickness of the graphite substrate was 0.05 mm, the thickness of the resin coating was 5 μm, and the viscosity of the resin coating was 45 cP.

[0058] 3) Epoxy resin, graphite, binder, and solvent are mixed to obtain a conductive slurry. The conductive slurry is then coated onto the outer surface of the resin coating. After curing and drying, a conductive coating is obtained, which is the graphite electrode plate. The thickness of the conductive coating is 25 μm, and the viscosity of the conductive coating is 200 cP.

[0059] Example 4

[0060] 1) Prepare a graphite substrate by roll forming a graphite blank and etching the flow field region to obtain a graphite substrate.

[0061] 2) The graphite substrate was immersed in a polyacrylonitrile solution. During immersion under negative pressure, the vacuum level was 1 Pa, and the immersion time was 60 min. During immersion under normal pressure, the immersion time was 30 min. The immersed substrate was then vacuum-dried and cured to obtain a graphite substrate with a resin coating on its surface. During the vacuum drying and curing process, the vacuum level was 10 Pa, the drying temperature was 170℃, and the curing time was 30 min. The thickness of the graphite substrate was 0.05 mm, the thickness of the resin coating was 5 μm, and the viscosity of the resin coating was 10 cP.

[0062] 3) Epoxy resin, graphite, binder, and solvent are mixed to obtain a conductive slurry. The conductive slurry is then coated onto the outer surface of the resin coating. After curing and drying, a conductive coating is obtained, which is the graphite electrode plate. The thickness of the conductive coating is 25 μm, and the viscosity of the conductive coating is 50 cP.

[0063] The graphite electrode plate obtained using the method provided in this application maintains excellent conductivity and also possesses superior sealing performance. By impregnating a graphite substrate in a resin solution, an intermediate is obtained. The resin adheres tightly to the surface of the graphite substrate, filling micropores and defects in the matrix, thereby forming an effective barrier to prevent electrolytes or other chemicals from penetrating into the matrix. A conductive coating is then prepared on at least one side of the intermediate, covering the surface of the resin. This conductive coating further seals any unsealed blind holes and through holes in the resin, thereby improving the hermeticity of the graphite electrode plate. Therefore, the preparation method provided in this application can yield a graphite electrode plate with good sealing properties.

[0064] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," "some implementations," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0065] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a graphite electrode plate, characterized in that, include: Preparation of graphite substrates; The graphite substrate is immersed in a resin solution and then cured to obtain an intermediate. A conductive coating is prepared on the surface of the intermediate to obtain a graphite electrode plate; The conductive coating further seals the unsealed blind holes and through holes of the resin solution; The steps for preparing the conductive coating include: A conductive paste is obtained by mixing thermosetting resin, filler, binder and solvent; The conductive paste is coated onto the surface of the intermediate to obtain a conductive coating. The filler includes at least one of graphite, carbon nanotubes, copper, nickel, and silver; The viscosity of the conductive paste is greater than the viscosity of the resin solution; The viscosity of the resin solution is less than 50 cP; The viscosity of the conductive paste is 50 cP-200 cP.

2. The method according to claim 1, characterized in that, The thickness of the graphite substrate is 0.05mm-0.5mm.

3. The method according to claim 1, characterized in that, The resin solution includes at least one of polyacrylonitrile, polyvinyl alcohol, polyvinylidene fluoride, and polyphenylene ether.

4. The method according to claim 1, characterized in that, The thickness of the conductive coating is greater than or equal to 25 μm.

5. The method according to claim 1, characterized in that, The thermosetting resin includes at least one of epoxy resin, polyurethane resin and acrylate resin.

6. A graphite electrode plate, characterized in that, The graphite electrode plate is prepared by any one of claims 1-5.

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