Fuel cell electrode plate based on partition function design and preparation method thereof

Abstract

The invention relates to a fuel cell polar plate based on partition function design and a preparation method thereof. The fuel cell polar plate comprises a frame area and a flow channel reaction area arranged in the frame area, an oxygen inlet / outlet, a hydrogen inlet / outlet and a cooling liquid inlet / outlet are formed in each of two sides of the runner reaction area; the two sides of the flow channel reaction area are respectively communicated with the gas distribution area, the oxygen inlet / outlet, the hydrogen inlet / outlet and the cooling liquid inlet / outlet are communicated with the gas distribution area through distribution flow channels, and hydrogen, oxygen and cooling liquid enter the flow channel reaction area through the gas distribution area or flow out of the flow channel reaction area. The runner reaction zone is prepared from the following raw materials in parts by weight: 80-120 parts of graphite powder, 15-20 parts of a binder, 1-5 parts of a curing agent, 1-5 parts of an accelerant, 15-25 parts of conductive carbon black and 5-20 parts of carbon nanotubes. The fuel cell polar plate disclosed by the invention is designed based on a partition function, and different regions are respectively designed through partition regulation and control so as to consider the conductivity and the bending strength of the fuel cell polar plate.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cells, and in particular relates to a fuel cell polar plate based on a partitioned functional design and a preparation method thereof. Background Art

[0002] The main functions of bipolar plates in a proton exchange membrane fuel cell stack are to separate the reactant gases and direct the reactant gases into the fuel cell through the flow field, collect and conduct current, support the membrane electrode, and undertake heat dissipation and drainage of the entire fuel cell. The functions of bipolar plates are summarized as follows: (1) Support the membrane electrode (MEA); (2) Separate each single cell; (3) Separate the cathode and anode reactant gases to prevent them from mixing with each other; (4) Provide electrical connections; (5) Transport the reactant gases and distribute them evenly; (6) Conduct the reaction heat; (7) Remove water byproducts; (8) Bear the assembly preload. The bipolar plates form the skeleton of the fuel cell stack, provide electrical connections between cells, promote water and heat management through the cells, channelize the reactant gases, and remove the reaction products. The bipolar plates constitute most of the weight and volume of the fuel cell stack, support the membrane electrode, and provide mechanical stability for the entire stack.

[0003] The main areas of the composite graphite bipolar plate are divided into the frame area, the inlet and outlet area, the gas distribution area and the flow channel reaction area. During the assembly process, the frame area of ​​the bipolar plate plays the role of bearing the preload and fixing the whole. During the working reaction of the battery stack, the composite graphite bipolar plate plays an important role in realizing the conductive connection of adjacent single cells through the series structure, and allowing the fuel, oxidant, coolant and reaction products to be distributed and transmitted in a specific flow field, structural support, distribution and blocking of reaction gases, current collection and transmission, regulating internal temperature, and guiding the discharge of reaction by-products. Therefore, the bipolar plate should have good electrical conductivity, thermal conductivity, mechanical strength and gas barrier properties. The inlet and outlet areas and gas distribution areas of the bipolar plate should have good strength, and the flow channel reaction area should have good electrical conductivity, thermal conductivity and strength.

[0004] In addition, the material selection of fuel cell bipolar plates is the same, whether they are metal bipolar plates, graphite bipolar plates or composite graphite bipolar plates. The same plate plays different roles in the assembly and reaction process of the fuel cell, and these functions have different requirements for processing design. For different bipolar plates, the selection of different materials and processing schemes will result in different performance of the bipolar plates. If the three types of bipolar plates today use the same substrate and the same processing scheme during the processing, the fuel cell bipolar plates cannot meet these performance requirements at the same time. For metal bipolar plates, their bending strength and conductivity are more prominent, but due to their corrosion resistance and short service life, the cost of using metal bipolar plates is higher. Graphite plates and composite graphite plates have good corrosion resistance and long service life, especially composite graphite bipolar plates, whose conductive fillers have good electrical conductivity and thermal conductivity, and have better processability and balance than graphite bipolar plates. However, the bending strength of the composite graphite bipolar plate is not strong, and the sealing performance is not as good as that of the metal bipolar plate, which makes the composite graphite bipolar plate play a less important role in the assembly process than the metal bipolar plate.

[0005] Therefore, it is urgent to develop a fuel cell plate based on zoning functional design, and to design different areas separately through zoning regulation to enhance the conductivity and bending strength of the fuel cell plate. Summary of the invention

[0006] The purpose of the present invention is to provide a fuel cell plate based on a partitioned functional design and a preparation method thereof, so as to take into account both the electrical conductivity and the bending strength of the fuel cell plate.

[0007] The present invention first provides a fuel cell plate based on a zoning functional design, comprising a frame area and a flow channel reaction area arranged in the frame area; oxygen inlet and outlet, hydrogen inlet and outlet, and coolant inlet and outlet are arranged on both sides of the flow channel reaction area;

[0008] The two sides of the flow channel reaction zone are respectively connected to the gas distribution zone, and the oxygen inlet and outlet, the hydrogen inlet and outlet, and the coolant inlet and outlet are all connected to the gas distribution zone through the distribution flow channel, and the hydrogen, oxygen and coolant enter the flow channel reaction zone or flow out of the flow channel reaction zone through the gas distribution zone;

[0009] The flow channel reaction zone is made of the following raw materials in parts by weight: 80-120 parts of graphite powder, 15-20 parts of binder, 1-5 parts of curing agent, 1-5 parts of accelerator, 15-25 parts of conductive carbon black, and 5-20 parts of carbon nanotubes; wherein the particle size of the graphite substrate is 325-2500 meshes.

[0010] Furthermore, the particle size of the graphite substrate is 325-1500 mesh.

[0011] Furthermore, the binder includes one or more of phenolic resin, polypropylene, polyvinylidene fluoride, polyvinylidene fluoride and copolymers thereof, styrene-butadiene rubber, polytetrafluoroethylene, and carboxymethyl cellulose, preferably phenolic resin.

[0012] Furthermore, the average particle size of the conductive carbon black is 30-45 nm, preferably 40 nm.

[0013] Furthermore, the aspect ratio of the carbon nanotubes is 500-2000.

[0014] Furthermore, the flow channel reaction zone is prepared by the following method: adding a graphite substrate to a binder solution, mixing, drying and crushing to obtain a thermoforming masterbatch; adding conductive carbon black and carbon nanotubes to the binder solution respectively, ultrasonicating, stirring and drying for standby use; mixing a thermoforming masterbatch curing agent, an accelerator and pre-treated conductive carbon black and carbon nanotubes and filling them into a mold, followed by pressurizing for thermoforming, and finally obtaining the flow channel reaction zone.

[0015] Furthermore, the thermoforming temperature is 170-190°C, preferably 180°C.

[0016] Furthermore, the thermoforming pressure is at least 50 MPa, and the pressurizing time is 10-20 min, preferably 15 min.

[0017] Furthermore, the frame area is made of the following components in parts by weight: 80-90 parts of graphite substrate, 4-6 parts of reinforcing material, and 8-12 parts of binder. The particle size of the graphite substrate is 325 meshes to 2500 meshes.

[0018] Furthermore, the gas distribution zone is made of the following components in parts by weight: 86-94 parts of graphite substrate, 4-6 parts of reinforcing material, and 4-6 parts of binder. The particle size of the graphite substrate is 325 meshes to 2500 meshes.

[0019] Furthermore, in the frame area and the gas distribution area, the graphite substrate is preliminarily subjected to surface oxidation treatment using epoxy resin.

[0020] Furthermore, the specific steps of the surface oxidation treatment are: dispersing bisphenol A epoxy resin and 4,4'-diaminodiphenyl sulfone in an organic solvent at a mass ratio of 10:(2-4), and obtaining an epoxy resin solution after ultrasonic dissolution; adding a graphite substrate to the epoxy resin solution and mixing it evenly, drying to remove the solvent, and then crushing and hot pressing in sequence to obtain a graphite substrate after surface oxidation treatment.

[0021] Furthermore, in the frame region, the particle size of the graphite substrate is 2500 meshes, and the reinforcing material includes one of carbon fiber, glass fiber composite material or metal material.

[0022] Furthermore, in the frame area, reinforcing ribs or a supporting frame are provided around or in the frame area.

[0023] Furthermore, in the gas distribution area, the particle size of the graphite substrate is 1000 mesh, the reinforcing material is a carbon fiber reinforced composite material, and the length of the carbon fiber is 0.8-1.5 mm; the surface of the gas distribution area is coated with a polymer or ceramic coating.

[0024] The present invention also provides a method for preparing a fuel cell plate based on a zoning functional design, comprising the following steps: respectively pressing out a frame area, a flow channel reaction area, an oxygen inlet and outlet, a hydrogen inlet and outlet, a coolant inlet and outlet, and a gas distribution area by a molding method or a thermoforming method; using the frame area as a base, pressing the remaining areas tightly onto the frame area to obtain the fuel cell plate.

[0025] Furthermore, the fuel cell bipolar plate is prepared by multi-layer extrusion, with the frame area as the base for one rolling process, and multiple rolling processes to press and process the gas distribution area, flow channel reaction area and inlet and outlet areas on the frame area to form a complete bipolar plate structure.

[0026] Furthermore, post-processing steps such as oxidation treatment, embedding of conductive and thermal conductive groups, and coating can be performed on each region according to actual needs.

[0027] The present invention adopts a zoning design method to perform performance analysis on each area of ​​the fuel cell plate, and then performs steps such as clarifying design requirements, process processing, and connection design.

[0028] The most important thing about the flow channel reaction zone in the present invention is to maintain a balance between conductivity and flexural strength. Analyze the design scheme of the flow channel reaction area of ​​the bipolar plate, select graphite of suitable particle size, select phenolic resin as a binder, conductive carbon black, carbon nanotubes, etc. as auxiliary fillers and control the corresponding ratio. Phenolic resin is selected as a binder, natural flake graphite is selected as a conductive substrate, and highly conductive nanoparticle materials are used as auxiliary fillers. Wet chemical co-precipitation is performed to arrange the particles in an orderly manner to balance flexural strength, conductivity, air tightness and thermal conductivity; then the molding pressure, holding time and curing temperature in the preparation process are controlled to maintain the balance of conductivity, thermal conductivity, flexural strength and other properties. During the molding process, the flow channel reaction zone can also use a multi-layer structure design according to actual needs, such as surface treatment, increasing the introduction of conductive groups, coating oxidized group coatings, etc., and the bipolar plate is subjected to grinding, polishing or flatness correction and other processing processes.

[0029] The present invention can also selectively improve the bending strength of the frame area of ​​the composite graphite fuel cell plate, such as increasing the cross-sectional size of the frame, increasing the thickness and height of the frame, or using reinforcing ribs to improve the rigidity and strength of the frame. The optimization of the frame area can be performed by optimizing the design of the frame structure through tools such as finite element analysis, so that it can show better bending strength when subjected to bending loads. Use reinforcing materials, select materials with high strength and rigidity as the construction materials of the frame; use interface bonding reinforcement, by applying high-strength adhesives or interface materials between the frame and other components; add additional structural supports around or inside the frame to increase the bending strength.

[0030] The present invention can also selectively improve the performance of the gas distribution area and the inlet and outlet areas, such as improving the hydrophilic and hydrophobic properties, changing the flow channel structure, chemically modifying the surface of the graphite bipolar plate by surface modification (adding corresponding groups), adding hydrophilic and hydrophobic fillers to the gas distribution area, etc.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention is different from the traditional fuel cell bipolar plate manufacturing scheme. The fuel cell plates are designed and manufactured in a zoned manner, so that the performance advantages of each area are more prominent. The flow channel reaction area has better and more balanced conductivity and bending strength, and the frame area, gas distribution area and inlet and outlet areas have better bending strength, ultimately achieving a balance between the conductivity and bending strength of the fuel cell plates.

[0033] (2) The flow channel reaction zone of the present invention selects graphite of suitable particle size, and selects binders, conductive carbon black, carbon nanotubes, etc. as auxiliary fillers, and arranges the particles in an orderly manner by controlling the component ratio and performing wet chemical co-precipitation to achieve an effective balance of properties such as bending strength and conductivity.

[0034] (3) The border region and the gas distribution region of the present invention undergo surface oxidation treatment on the graphite substrate, which can better improve the toughness and bending strength of the border region.

[0035] (4) The partitioned manufacturing design of the present invention enables the bipolar plate to be replaced more quickly in problematic areas after a problem occurs, and to carry out targeted regional repairs, which is fast and convenient and reduces production and use costs.

[0036] (5) The present invention can produce fuel cell bipolar plates with more comprehensive and extensive application scenarios. Traditional bipolar plates can only be manufactured in a fixed manner and cannot meet applications with different performance requirements. The partitioned functional design of the present invention can be manufactured in a targeted manner according to the different bipolar plate performances required in different scenarios, and the application is more comprehensive. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the structure of the anode plate of the fuel cell of the present invention.

[0038] Figure 2 It is a schematic diagram of the structure of the cathode plate of the fuel cell of the present invention.

[0039] Figure 3 A schematic diagram of the flow chart designed for the partitioning function of the present invention.

[0040] Description of the markings in the figure:

[0041] 1-frame area, 2-flow channel reaction area, 3-oxygen inlet and outlet, 4-hydrogen inlet and outlet, 5-coolant inlet and outlet, 6-gas distribution area. DETAILED DESCRIPTION

[0042] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0043] Unless otherwise specified, the reagents, methods, instruments and equipment used in the examples and comparative examples are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available. Among them, the graphite substrate is natural flake graphite, with a model of 100 mesh to 2500 mesh and a purity of 99.5%, purchased from Shenzhen Hanhui Graphite; the phenolic resin is water-soluble bisphenol A epoxy resin 6002, with a solid content of 70%, purchased from McLean Reagent; the conductive carbon black is model XF115, purchased from Xianfeng Nano Co., Ltd., with a particle size of 30-45nm; the carbon nanotubes are multi-walled carbon nanotubes, model XFM01, purchased from Xianfeng Nano Co., Ltd., with a length of 7-15μm and a diameter of 5-15nm; the carbon fiber is chopped carbon fiber, purchased from Xianfeng Nano Co., Ltd., with a length of 1mm; the curing agent is 4,4'-diaminodiphenyl sulfone, with a CAS number of 80-08-0; the accelerator is 2-methylimidazole, with a purity of 98%, purchased from Sinopharm Chemical Reagent Co., Ltd.; and the bisphenol A epoxy resin (DGEBA) is purchased from Sinopharm Chemical Reagent Co., Ltd.

[0044] The present invention provides a fuel cell plate based on a zoning function design, and is divided into an anode plate and a cathode plate according to the actual needs of the fuel cell. The fuel cell plate includes a frame area 1 and a flow channel reaction area 2 arranged in the frame area 1, and both sides of the flow channel reaction area 2 are provided with an oxygen inlet and outlet 3, a hydrogen inlet and outlet 4, and a coolant inlet and outlet 5. Each inlet and outlet on both sides is independently selected from the inlet or outlet of the corresponding fluid according to actual needs, and no mandatory regulations are made here. The two sides of the flow channel reaction area 2 are respectively connected to the gas distribution area 6, and the oxygen inlet and outlet 3, the hydrogen inlet and outlet 4, and the coolant inlet and outlet 5 are all connected to the gas distribution area 6 through the distribution channel, and hydrogen, oxygen and coolant can enter the flow channel reaction area 2 or flow out of the flow channel reaction area 2 through the gas distribution area 6. Figure 1 and Figure 2 They are the structures of the anode plate and the cathode plate respectively. The difference between the two is that the hydrogen inlet in the anode plate is connected to the gas distribution area 6, and the oxygen inlet in the cathode plate is connected to the gas distribution area 6. The flow channel reaction area 2 of the anode plate has a tighter flow channel structure.

[0045] The fuel cell bipolar plates finally prepared in the following embodiments and comparative examples are all based on the above structure, and the selection of the inlet and outlet of each fluid will not affect the final conductivity and bending strength of the fuel cell bipolar plate.

[0046] In addition, the present invention conducts conductivity test and bending strength test on the fuel cell plates finally prepared in the following embodiments and comparative examples.

[0047] Conductivity test: The conductivity is measured by measuring the in-plane conductivity and area specific resistance. The in-plane conductivity is tested by the four-probe test method to obtain the square resistance of the sample. The size of the tested samples is 2500mm. 2 , thickness h = 0.5mm, the in-plane conductivity is tested by four-probe test method to get the square resistance R0 of the sample. The in-plane conductivity is deduced by the formula ζ = 1 / R0h. The gold-plated copper electrode is directly pressurized to 2MPa, and the electrode contact resistance and the electrode volume resistance R1 are tested. Then the composite graphite sample is placed between the electrodes and slowly pressurized to 2MPa. The loop resistance R2 is recorded. The volume resistance R S =S(R2-R1), where S is the sample area. The volume resistance (R G ), then place the samples on both sides of the sample, gradually pressurize to 2MPa, record the loop resistance R3, and calculate the contact resistance R C =S[R3-R1-2R G -R S ] / 2, the conductivity was measured, and the national standard for conductivity was a conductivity greater than 100S / cm.

[0048] Bending strength test: The test was conducted by Instron 3665 universal material testing machine using the three-point bending method. The bending stress corresponding to the maximum bending load during the bending test is the bending strength. The test conditions were a span of 50 mm and a pressure head moving speed of 1.5 mm / min. The national standard for bending strength is greater than or equal to 25 MPa.

[0049] Embodiment 1:

[0050] This embodiment provides a fuel cell plate based on a partitioned functional design. Taking the anode plate as an example, the specific preparation method is as follows:

[0051] (1) Preparation of the frame area: 5 parts of carbon fiber, 85 parts of 2500 mesh graphite substrate and 10 parts of binder were mixed and evenly filled into a mold, and pressed to 30 MPa at a pressure rate of 5 MPa / min at room temperature. The mold was then heated to 170°C and kept at constant temperature and pressure for 30 minutes to completely solidify the resin, and finally the frame area was prepared.

[0052] Among them, the graphite substrate is pre-treated with surface oxidation, and the specific steps are as follows: bisphenol A epoxy resin and 4,4'-diaminodiphenyl sulfone are dispersed in acetone at a mass ratio of 10:3, and an epoxy resin solution is obtained after ultrasonic dissolution. The graphite substrate is added to the epoxy resin solution and an appropriate amount of ethanol is added to facilitate subsequent volatilization. After the above mixture is fully mixed by mechanical stirring, the mixture is placed in a 60°C oven and completely dried to remove residual solvent. The dried mixture is then crushed using a colloid mill, and the precursor is hot-pressed for 90 minutes at 180°C and 20MPa pressure using a flat vulcanizer to prepare an oxidized graphite substrate.

[0053] (2) Preparation of gas distribution area and fluid inlet and outlet: 90 parts of 1000 mesh high-density graphite; 5 parts of carbon fiber reinforced composite material (specifically carbon fiber woven cloth CFF, 1K, thickness 0.1mm, purchased from Zhongfu Carbon Fiber), where the carbon fiber length is 1mm; 5 parts of adhesive. The specific molding process is the same as that of the frame area. The graphite substrate is pre-oxidized, and the treatment steps are the same as those of the frame area.

[0054] (3) Preparation of flow channel reaction zone: 20 g of phenolic resin binder was dissolved in 400 mL of anhydrous ethanol, stirred at 500 rpm and ultrasonically treated for 10 minutes to obtain a uniform phenolic resin solution which was divided into three portions for standby use.

[0055] 100g of flake graphite powder was dispersed into one of the phenolic resin solutions and stirred at 500rpm for 30min. The particle size of the flake graphite in this embodiment was 1000 mesh. The mixture was then dried in a blast drying oven at a constant temperature of 60°C for 2h to completely remove the solvent. The dried sample was crushed in a mechanical crusher for 1 minute to obtain a masterbatch ready for thermoforming.

[0056] 25 g of conductive carbon black was separately dispersed into one of the phenolic resin solutions, ultrasonically treated for 30 minutes, mechanically stirred at a speed of 500 rpm for 10 minutes, and dried and crushed at 60° C. to obtain pretreated conductive carbon black.

[0057] 15 g of carbon nanotubes were ultrasonically dissolved for 30 minutes and then dispersed into one portion of the phenolic resin solution to make the dispersed carbon nanotubes dispersed into a relatively thick slurry, which was then dried and crushed at 60° C. to obtain pretreated carbon nanotubes.

[0058] The masterbatch to be used, 10g of curing agent, 10g of accelerator, and pre-treated conductive carbon black and carbon nanotubes were mixed evenly, and then the preliminary flow channel reaction zone was prepared by molding. The specific molding process and parameters are: the composite graphite powder is filled into the mold and pressurized to 50MPa at 180°C to complete the preparation of the composite graphite plate. The specific pressurization time is 15min, and the flow channel reaction zone is finally obtained.

[0059] (4) Assembly of fuel cell plates:

[0060] Taking the anode plate as an example, the frame area is first used as the base for roller pressing, and then the flow channel reaction area, hydrogen inlet and gas distribution area are squeezed on the frame area in turn. Then, the coolant inlet and outlet and oxygen inlet are aligned with the cathode plate, and extrusion assembly is performed to finally obtain a complete fuel cell bipolar plate.

[0061] Embodiment 2:

[0062] This embodiment provides a fuel cell plate based on a zoning function design. The difference from Embodiment 1 is that the particle size of the flake graphite used in this embodiment is 325 mesh.

[0063] Embodiment 3:

[0064] This embodiment provides a fuel cell plate based on a zoning function design. The difference from Embodiment 1 is that the particle size of the flake graphite used in this embodiment is 1500 mesh.

[0065] Embodiment 4:

[0066] This embodiment provides a fuel cell plate based on a zoning function design. The difference from Embodiment 1 is that the particle size of the flake graphite used in this embodiment is 2500 mesh.

[0067] Embodiment 5:

[0068] This embodiment provides a fuel cell plate based on a zoning functional design. The difference from Embodiment 1 is that the added amounts of the components in the flow channel reaction zone of this embodiment are: 20g phenolic resin binder, 100g flake graphite powder, 20g conductive carbon black, and 15g carbon nanotubes.

[0069] Embodiment 6:

[0070] This embodiment provides a fuel cell plate based on a zoning functional design. The difference from Embodiment 1 is that the added amounts of the components in the flow channel reaction zone of this embodiment are: 20g phenolic resin binder, 100g flake graphite powder, 30g conductive carbon black, and 15g carbon nanotubes.

[0071] Embodiment 7:

[0072] This embodiment provides a fuel cell plate based on a zoning function design. The difference from Embodiment 1 is that the added amounts of the components in the flow channel reaction zone of this embodiment are: 20g phenolic resin binder, 100g flake graphite powder, 25g conductive carbon black, and 20g carbon nanotubes.

[0073] Embodiment 8:

[0074] This embodiment provides a fuel cell plate based on a zoning functional design. The difference from Embodiment 1 is that the added amounts of the components in the flow channel reaction zone of this embodiment are: 20g phenolic resin binder, 100g flake graphite powder, 25g conductive carbon black, and 5g carbon nanotubes.

[0075] Comparative Example 1:

[0076] This comparative example provides a fuel cell plate, which is different from Example 1 in that the particle size of the flake graphite used in this comparative example is 100 mesh.

[0077] Comparative Example 2:

[0078] This comparative example provides a fuel cell plate, which is different from Example 1 in that the particle size of the flake graphite used in this comparative example is 3000 mesh.

[0079] Comparative Example 3:

[0080] This comparative example provides a fuel cell plate, which is different from Example 1 in that 25 g of carbon nanotubes are added in this comparative example.

[0081] Comparative Example 4:

[0082] This comparative example provides a fuel cell plate, which is different from Example 1 in that 30 g of carbon nanotubes are added in this comparative example.

[0083] The addition amounts of the components of the fuel cell plates of the above-mentioned embodiments and comparative examples of the present invention, the test results of the electrical conductivity, and the test results of the flexural strength are summarized in Table 1.

[0084] Table 1 Addition amount of each component of fuel cell plate, test results of conductivity and bending strength

[0085]

[0086]

[0087] According to the data of Examples 1-4 and Comparative Examples 1-2 in the above table, the graphite mesh number added by the present invention is within the range of 325-2500 mesh, and all show an in-plane conductivity of >100S / cm, especially within the range of 325-1500 mesh, the conductivity is >220S / cm. When the graphite particle size of Comparative Example 1 is larger, although the conductivity is significantly improved, the flexural strength is significantly reduced; the graphite particle size of Comparative Example 2 is further reduced, but the conductivity is significantly reduced. The above two can no longer take into account the balance between the conductivity and flexural strength of the battery plate. Within the range of 325-2500 mesh, the volume density of graphite particles increases, forming more conductive paths, and the in-plane conductivity of the composite plate is in a dynamic equilibrium state. In addition, within this particle size range, since the conductive carbon black has a nanometer-scale particle size, the conductive carbon black can be more evenly dispersed in the contact gap of the graphite, and the conductive carbon black is more likely to form a conductive bridge between smaller graphite gaps to increase the conductive path of the composite material. When the graphite particle size is further reduced, the particle size difference between the conductive carbon black and the flake graphite particles is reduced, and the conductive carbon black can no longer be well filled in the gaps of the flake graphite, destroying the stacking orientation of the graphite particles. Therefore, the mesh size of the graphite substrate added in the present invention is controlled between 325-2500 meshes.

[0088] According to the data of the above table of examples and comparative examples, the amount of carbon black added should be controlled within a certain range. Within this range, as the amount of carbon black increases, the conductivity of the graphite composite plate shows a trend of first increasing and then rapidly decreasing. When the carbon black concentration is 30g (Example 6), the conductivity is 309.28S / cm, which has decreased to a certain extent compared with the amount added in Example 2; continuing to add conductive carbon black will lead to a rapid decrease in conductivity, and the conductivity and flexural strength are extremely unbalanced.

[0089] According to the data of the embodiments and comparative examples in the above table, the amount of carbon nanotubes added should be controlled within a certain range, and the amount of carbon nanotubes added is 5-20g. As the amount of carbon nanotubes added increases, the bending strength of the graphite composite plate gradually increases as a whole, and the conductivity increases first and then decreases. For carbon nanotubes exceeding the addition amount range, such as comparative examples 3-4, the conductivity decreases significantly.

[0090] The present invention is different from the traditional fuel cell bipolar plate manufacturing scheme. Instead, the fuel cell plate is designed and manufactured in a zoned manner, so that the performance advantages of each area are more prominent, the flow channel reaction area has better and more balanced conductivity and bending strength, the frame area, gas distribution area and inlet and outlet areas have better bending strength, and finally the balance between the conductivity and bending strength of the fuel cell plate as a whole is achieved.

[0091] The present invention is different from the traditional fuel cell bipolar plate manufacturing scheme. Instead, the fuel cell plate is designed and manufactured in a zoned manner, so that the performance advantages of each area are more prominent, the flow channel reaction area has better and more balanced conductivity and bending strength, the frame area, gas distribution area and inlet and outlet areas have better bending strength, and finally the balance between the conductivity and bending strength of the fuel cell plate as a whole is achieved.

[0092] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A fuel cell plate based on a partition function design, characterized in that: It includes a frame area and a flow channel reaction area arranged in the frame area; oxygen inlet and outlet, hydrogen inlet and outlet, and coolant inlet and outlet are arranged on both sides of the flow channel reaction area; The two sides of the flow channel reaction zone are respectively connected to the gas distribution zone, and the oxygen inlet and outlet, the hydrogen inlet and outlet, and the coolant inlet and outlet are all connected to the gas distribution zone through the distribution flow channel, and the hydrogen, oxygen and coolant enter the flow channel reaction zone or flow out of the flow channel reaction zone through the gas distribution zone; The flow channel reaction zone is made of the following raw materials in parts by weight: 80-120 parts of graphite powder, 15-20 parts of binder, 1-5 parts of curing agent, 1-5 parts of accelerator, 15-25 parts of conductive carbon black, and 5-20 parts of carbon nanotubes; wherein the particle size of the graphite substrate is 325-2500 meshes.

2. A fuel cell plate based on zoning functional design according to claim 1, characterized in that: The binder includes one or more of phenolic resin, polypropylene, polyvinylidene fluoride, styrene-butadiene rubber, polytetrafluoroethylene, and carboxymethyl cellulose.

3. The fuel cell plate based on zoning functional design according to claim 1, characterized in that: The average particle size of the conductive carbon black is 30-45 nm.

4. The fuel cell plate based on zoning functional design according to claim 1, characterized in that: The aspect ratio of the carbon nanotubes is 500-2000.

5. The fuel cell plate based on zoning functional design according to claim 1, characterized in that: The flow channel reaction zone is prepared by the following method: The graphite substrate is added to the binder solution, mixed, dried and crushed to obtain a thermoforming masterbatch; the conductive carbon black and carbon nanotubes are added to the binder solution respectively, ultrasonicated, stirred and dried for standby use; the thermoforming masterbatch, curing agent, accelerator and pre-treated conductive carbon black and carbon nanotubes are mixed and filled into a mold, followed by pressurization for thermoforming, and finally the flow channel reaction zone is obtained.

6. A fuel cell plate based on zoning functional design according to claim 5, characterized in that: The temperature of the thermoforming is 170-190° C., the pressure is at least 50 MPa, and the pressing time is 10-20 min.

7. The fuel cell plate based on zoning functional design according to claim 1, characterized in that: The frame area is made of the following components by weight: 80-90 parts of graphite substrate, 4-6 parts of reinforcing material, and 8-12 parts of binder, and the particle size of the graphite substrate is 325 meshes to 2500 meshes; The gas distribution zone is made of the following components by weight: 86-94 parts of graphite substrate, 4-6 parts of reinforcing material, and 4-6 parts of binder. The particle size of the graphite substrate is 325 meshes to 2500 meshes. In the frame area and the gas distribution area, the graphite substrate is preliminarily subjected to surface oxidation treatment with epoxy resin.

8. The fuel cell plate based on zoning functional design according to claim 7, characterized in that: The specific steps of the surface oxidation treatment are: Bisphenol A epoxy resin and 4,4'-diaminodiphenyl sulfone are dispersed in an organic solvent at a mass ratio of 10:(2-4), and an epoxy resin solution is obtained after ultrasonic dissolution; a graphite substrate is added into the epoxy resin solution and mixed evenly, and then the solution is dried to remove the solvent, and then crushed and hot-pressed in sequence to obtain a graphite substrate after surface oxidation treatment.

9. The fuel cell plate based on zoning functional design according to claim 7, characterized in that: In the frame area, the particle size of the graphite substrate is 2500 mesh, and the reinforcing material includes one of carbon fiber, glass fiber composite material or metal material; reinforcing ribs or support frames are provided around or within the frame area; In the gas distribution area, the particle size of the graphite substrate is 1000 mesh, the reinforcement material is a carbon fiber reinforced composite material, and the length of the carbon fiber is 0.8-1.5 mm; the surface of the gas distribution area is coated with a polymer or ceramic coating.

10. A method for preparing a fuel cell plate based on a partitioned functional design according to any one of claims 1 to 9, characterized in that: The following steps are involved: The frame area, flow channel reaction area, oxygen inlet and outlet, hydrogen inlet and outlet, coolant inlet and outlet, and gas distribution area are pressed out separately by a hot forming method; the frame area is used as a base, and the remaining areas are pressed tightly onto the frame area to obtain a fuel cell plate.

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