Bipolar plate as well as preparation method and application thereof

Abstract

The invention provides a preparation method of a bipolar plate, which comprises the following steps: mixing crystalline flake graphite, expanded graphite, graphene, conductive carbon black, short carbon fiber, a water repellent agent and resin to obtain powder A; mixing crystalline flake graphite, spheroidal graphite, high-thermal-conductivity carbon fibers, resin and a hydrophilic additive to obtain powder B; after the powder A is flatly laid in a mold, then the powder B is flatly laid, or after the powder B is flatly laid in the mold, then the powder A is flatly laid, pre-pressing is carried out, then heating is carried out, the resin is cured, finally pressing is carried out, and the composite material is obtained. The invention also provides the bipolar plate prepared by the method, and a fuel cell comprising the bipolar plate.

Description

Technical Field

[0001] This invention belongs to the field of fuel cells, specifically relating to a bipolar plate, its preparation method, and its application. Background Technology

[0002] Bipolar plates are the core components of hydrogen fuel cell stacks, serving functions such as current conduction, electrical conductivity, thermal conductivity, and structural support. Currently, most mainstream graphite composite bipolar plates are homogeneous materials, whose electrical conductivity, airtightness, and mechanical strength are mutually constrained. For example, increasing the graphite content can enhance conductivity but often leads to increased brittleness and molding difficulties; increasing the resin content can improve toughness and airtightness but sacrifices conductivity. This homogeneous design makes it difficult to simultaneously meet the differentiated requirements of the flow field region (requiring high electrical and thermal conductivity) and the sealing region (requiring high density and high toughness).

[0003] To achieve the goal of different properties on both sides of a material, existing methods for manufacturing gradient materials, such as centrifugal sedimentation, chemical vapor infiltration, and multi-slurry co-extrusion, either have problems such as complex equipment, high cost, difficulty in producing dimensionally precise and airtight parts, or the inability to accurately control the composition and structure of the gradient interface. In particular, for graphite-resin systems with high solid content and high viscosity, it is difficult to achieve the ideal performance transition.

[0004] Chinese patent application CN115692755A discloses a method for preparing an integrated molded anode and cathode asymmetric hydrophilic-hydrophobic composite bipolar plate. This invention differs from existing technologies, which primarily focus on fabricating porous bipolar plates or bipolar plates with turbulent flow structures and preparing hydrophobic or hydrophilic coatings on bipolar plate surfaces. Instead, it takes a different approach, focusing on the performance of the composite bipolar plate's main material. By modifying the expanded graphite main material of the composite bipolar plate with hydrophilic and hydrophobic properties, a specialized mold with flow fields and hydrophilic / hydrophobic micro / nano structures was prepared. Using this mold, hydrophilic-modified expanded graphite / resin / conductive additive composite materials, unmodified graphite / resin / conductive additive composite materials, and hydrophobic-modified graphite / resin / conductive additive composite materials were sequentially laid down. A bipolar plate with both a hydrophilic anode and a hydrophobic cathode surface was then fabricated through a single molding process. The chemical potential difference between the two sides enhances the back diffusion of water, a product of the battery reaction, in the membrane electrode, promoting a self-equilibrium state of water distribution within the battery. This simplifies battery humidification and drainage accessories, improves battery efficiency, and reduces costs.

[0005] Chinese patent application CN117855510A discloses an expanded graphite (EG) composite bipolar plate and its preparation method. This invention employs a polymer blending process, introducing one or more of polyvinylidene fluoride (PVDF), modified polyvinylidene fluoride (a-PVDF), and hydrophobic fumed silica (SiO2) into acrylic resin (ARS) to prepare resin impregnation solutions with varying component contents. These solutions are then subjected to vacuum impregnation, cleaning, and curing to obtain the EG composite bipolar plate. This invention precisely controls the surface hydrophilicity / hydrophobicity of the EG composite bipolar plate by adjusting the components and proportions of the resin impregnation solution, thus preparing EG composite bipolar plates that meet the requirements of different application scenarios for surface hydrophilicity / hydrophobicity. The preparation method of this invention is simple to operate, highly efficient, and uses low-cost raw materials, which is conducive to large-scale production.

[0006] However, none of the above technical solutions have achieved the ideal performance transition of bipolar plates. Summary of the Invention

[0007] The first objective of this invention is to provide a method for preparing a bipolar plate that has high electrical and thermal conductivity on one side and good mechanical strength and moderate porosity on the other side, thus exhibiting high electrical conductivity, enhanced heat dissipation, and reliable sealing.

[0008] A second objective of this invention is to provide a bipolar plate prepared by the method described above.

[0009] A third objective of this invention is to provide an application of the bipolar plate.

[0010] This invention is achieved through the following technical solution:

[0011] A method for preparing a bipolar plate includes the following steps:

[0012] Flake graphite, expanded graphite, graphene, conductive carbon black, chopped carbon fibers, hydrophobic agent and resin are mixed to obtain powder A;

[0013] Flake graphite, spherical graphite, high thermal conductivity carbon fiber, resin and hydrophilic additives are mixed to obtain powder B;

[0014] After spreading powder A in the mold, powder B is spread in the mold, or powder B is spread in the mold and then powder A is spread in the mold. The mixture is pre-pressed, then heated to cure the resin, and finally pressed to obtain the final product.

[0015] In the powder A, the proportion of flake graphite is 10-20 wt%;

[0016] In the powder A, the proportion of expanded graphite is 40-45 wt%;

[0017] In the A powder, the proportion of graphene is 10-20 wt%;

[0018] In the A powder, the proportion of conductive carbon black is 5-10 wt%;

[0019] In the powder A, the proportion of short-cut carbon fibers is 5-10 wt%.

[0020] In the powder A, the proportion of hydrophobic agent is 5-10 wt%;

[0021] In the powder A, the resin accounts for 5-10 wt%.

[0022] In the B powder, the proportion of flake graphite is 50-55 wt%;

[0023] In the B powder, the proportion of spherical graphite is 5-20 wt%.

[0024] In the B powder, the proportion of high thermal conductivity carbon fiber is 5-20 wt%.

[0025] In the B powder, the resin accounts for 15-20 wt%;

[0026] In the B powder, the proportion of hydrophilic additives is 5-10 wt%.

[0027] The resin includes thermosetting resins;

[0028] The thermosetting resin includes phenolic resin or epoxy resin;

[0029] The phenolic resin includes WL6012 or MF1;

[0030] The epoxy resin includes E51, E44, or AG80.

[0031] The hydrophobic agent includes PE emulsion;

[0032] The PE content in the PE emulsion is 15-20 wt%.

[0033] The hydrophilic additives include sulfonated polyarylether ketones.

[0034] The pre-compression pressure is 8-12 MPa;

[0035] The pressing pressure is 50-55 MPa;

[0036] The pressing time is 180-200 seconds.

[0037] In the powder A, the average particle size of the flake graphite is 35-40 μm;

[0038] In the powder A, the average particle size of the expanded graphite is 80 mesh;

[0039] In the A powder, the average particle size of graphene is 10 μm, and the specific surface area is 800-850 m². 2 / g;

[0040] In the A powder, the average particle size of the conductive carbon black is 1-2 μm;

[0041] In the powder A, the length of the short-cut carbon fiber is 3mm and the diameter is 7-10μm.

[0042] In the B powder, the average particle size of the flake graphite is 50-55 μm;

[0043] In the B powder, the average particle size of the spherical graphite is 7-8 μm;

[0044] In the B powder, the high thermal conductivity carbon fiber is selected from mesophase pitch-based carbon fiber.

[0045] A bipolar plate prepared by the aforementioned method.

[0046] A fuel cell including the aforementioned bipolar plate.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] The method provided by this invention is simple and highly controllable, and can achieve precise gradient lay-up and densification of powder materials on a macroscopic scale.

[0049] The method provided by this invention can prepare an electrode plate with a hydrophilic side formed by powder B, characterized by high density, high electrical conductivity, high thermal conductivity, and high water permeability; and a hydrophobic side formed by powder A, characterized by high porosity, hydrophobicity, and high specific surface area. Simultaneously, a gradient transition zone exists in the middle of the hydrophilic and hydrophobic sides. This gradient transition zone can form a waterproof layer to prevent water exchange between the two sides.

[0050] The bipolar plate provided by this invention has the characteristics of being hydrophobic on one side and hydrophilic on the other, which can realize differentiated water management on both sides of the bipolar plate. Attached Figure Description

[0051] Figure 1 This shows an overview of the automotive fuel cell stack structure;

[0052] Figure 2 A cross-section of a single cell is shown;

[0053] Figure 3 The SEM image of the bipolar plate prepared from pure material B (Comparative Example 1) is shown.

[0054] Figure 4The SEM image of the bipolar plate prepared from pure material A (Comparative Example 2) is shown.

[0055] Figure 5 The SEM image of the bipolar plate prepared from the AB mixture (Example 1) is shown. Detailed Implementation

[0056] This invention first provides a method for preparing a bipolar plate, the specific steps of which are as follows:

[0057] 1. Powder Preparation: Based on the required gradient of the product, design and adjust the proportions of flake graphite, graphene, and thermosetting resin (such as phenolic resin and epoxy resin) to prepare two composite powders with different properties:

[0058] Powder A: Designed for gas diffusion and water management, the actual formulation consists of flake graphite, expanded graphite, graphene, conductive carbon black, short-cut carbon fiber, hydrophobic agent, and phenolic / epoxy resin.

[0059] Expanded graphite serves to provide a loose, three-dimensional, interconnected macroporous framework, ensuring channels for rapid gas diffusion and water evaporation. Graphene, on the other hand, fills the gaps between the flakes of graphite, creating a high-density conductive network.

[0060] The role of conductive carbon black is to fill some of the gaps between macroporous frameworks, forming mesoporous structures and secondary conductive networks, contributing high specific surface area, and optimizing interfacial contact.

[0061] The role of the hydrophobic agent (PE emulsion) is to encapsulate carbon materials as a hydrophobic agent, forming a stable hydrophobic surface and preventing liquid water from accumulating.

[0062] The role of chopped carbon fibers is to act as "steel bars," enhancing the mechanical strength of porous structures and preventing crushing.

[0063] Powder B: Designed to correspond to the electrical and thermal management sides, the actual formula consists of flake graphite, spherical graphite, high thermal conductivity carbon fiber, phenolic / epoxy resin, and hydrophilic additives.

[0064] The role of flake graphite is to provide a highly oriented sheet structure, enabling extremely high in-plane thermal and electrical conductivity pathways.

[0065] The function of spherical (microsphere) graphite is to fill the gaps between large flakes, increase the packing density and isotropy, reduce contact resistance, and enhance airtightness.

[0066] The role of high thermal conductivity carbon fiber is to be arranged along the thickness direction to establish a vertical fast heat conduction channel and reduce thermal resistance.

[0067] The role of hydrophilic additives is to use modified hydrophilic resins (such as sulfonated polyarylether ketones) to ensure hydrophilic contact with the catalyst layer or membrane.

[0068] 2. Powder spreading and pre-compression process parameters

[0069] The total depth of the mold cavity of the flat mold is 12mm. The hydraulic cylinder ejects the mold core, leaving a 7mm mold cavity volume. After A powder is applied, the hydraulic cylinder is pulled down to the bottom, leaving a 5mm mold cavity volume. After B powder is applied, pre-compression is performed with a pressure of 10MPa.

[0070] 3. Molding and curing

[0071] Temperature and pressure curves:

[0072] A stepped pressurization method is used. First, the mold is closed and the pressure is increased to 10 MPa. Then, the temperature is raised to 180℃ (to liquefy the resin), and the pressure is slowly increased to 50 MPa. This promotes the mutual penetration and diffusion of the two materials at the interface through the viscous flow of the resin / PE, naturally forming a gradient transition zone of components and pores, rather than a sharp interface. After holding the pressure for 180 seconds, the mold is opened and the product is removed after appropriate cooling.

[0073] The present invention will be further described below with reference to specific embodiments.

[0074] Example 1

[0075] Powder preparation:

[0076] Powder A: 15% flake graphite with an average particle size of 35 micrometers, 40% expanded graphite with an average particle size of 80 mesh, and powder with an average particle size of 10 μm and a specific surface area of ​​800 m². 2 The mixture consists of graphene (15%), conductive carbon black (8%) with an average particle size of 1 μm, short-cut carbon fibers (7%) with a length of 3 mm and an average diameter of 7 μm, PE emulsion (5%) with a PE content of 15 wt%, and epoxy resin E51 (10%).

[0077] Powder B is obtained by mixing flake graphite (55%) with an average particle size of 50 micrometers, spherical graphite (15%) with an average particle size of 7 micrometers, mesophase pitch-based carbon fiber (5%), epoxy resin E51 (20%), and sulfonated polyarylether ketone (5%).

[0078] Powder spreading and pre-compression process parameters

[0079] The total depth of the mold cavity of the flat mold is 12mm. The hydraulic cylinder ejects the mold core, leaving a 7mm mold cavity volume. After A powder is applied, the hydraulic cylinder is pulled down to the bottom, leaving a 5mm mold cavity volume. After B powder is applied, pre-compression is performed with a pressure of 10MPa.

[0080] Molding and curing:

[0081] A stepped pressurization method is used. First, the mold is closed and the pressure is increased to 10 MPa. Then, the temperature is raised to 180°C, and the pressure is slowly increased to 50 MPa. This promotes the interpenetration and diffusion of the two layers of powder A and powder B at the interface through the viscous epoxy resin, naturally forming a gradient transition zone of components and pores, rather than a sharp interface. After holding the pressure for 180 seconds, the mold is opened and the product is removed after appropriate cooling.

[0082] Example 2

[0083] Powder preparation:

[0084] Powder A: 10% flake graphite with an average particle size of 35 micrometers, 40% expanded graphite with an average particle size of 80 mesh, and powder with an average particle size of 10 μm and a specific surface area of ​​800 m². 2 The mixture consists of graphene (15%), conductive carbon black (8%) with an average particle size of 1 μm, short-cut carbon fibers (7%) with a length of 3 mm and an average diameter of 7 μm, PE emulsion (10%) with a PE content of 15 wt%, and epoxy resin E51 (10%).

[0085] Powder B is obtained by mixing flake graphite (55%) with an average particle size of 50 micrometers, spherical graphite (10%) with an average particle size of 7 micrometers, mesophase pitch-based carbon fiber (10%), epoxy resin E51 (20%), and sulfonated polyarylether ketone (5%).

[0086] Powder spreading and pre-compression process parameters

[0087] The total depth of the mold cavity of the flat mold is 12mm. The hydraulic cylinder ejects the mold core, leaving a 7mm mold cavity volume. After A powder is applied, the hydraulic cylinder is pulled down to the bottom, leaving a 5mm mold cavity volume. After B powder is applied, pre-compression is performed with a pressure of 10MPa.

[0088] Molding and curing:

[0089] A stepped pressurization method is used. First, the mold is closed and the pressure is increased to 10 MPa. Then, the temperature is raised to 180°C, and the pressure is slowly increased to 50 MPa. This promotes the interpenetration and diffusion of the two layers of powder A and powder B at the interface through the viscous epoxy resin, naturally forming a gradient transition zone of components and pores, rather than a sharp interface. After holding the pressure for 180 seconds, the mold is opened and the product is removed after appropriate cooling.

[0090] Example 3

[0091] Powder preparation:

[0092] Powder A: 15% flake graphite with an average particle size of 35 micrometers, 40% expanded graphite with an average particle size of 80 mesh, and powder with an average particle size of 10 μm and a specific surface area of ​​800 m². 2The mixture consists of graphene (15%), conductive carbon black (10%) with an average particle size of 1 μm, short-cut carbon fibers (5%) with a length of 3 mm and an average diameter of 7 μm, PE emulsion (5%) with a PE content of 15 wt%, and epoxy resin E51 (10%).

[0093] Powder B is obtained by mixing flake graphite (55%) with an average particle size of 55 micrometers, spherical graphite (20%) with an average particle size of 8 micrometers, mesophase pitch-based carbon fiber (5%), epoxy resin E51 (15%), and sulfonated polyarylether ketone (5%).

[0094] Powder spreading and pre-compression process parameters

[0095] The total depth of the mold cavity of the flat mold is 12mm. The hydraulic cylinder ejects the mold core, leaving a 7mm mold cavity volume. After A powder is applied, the hydraulic cylinder is pulled down to the bottom, leaving a 5mm mold cavity volume. After B powder is applied, pre-compression is performed with a pressure of 10MPa.

[0096] Molding and curing:

[0097] A stepped pressurization method is used. First, the mold is closed and the pressure is increased to 10 MPa. Then, the temperature is raised to 180°C, and the pressure is slowly increased to 50 MPa. This promotes the interpenetration and diffusion of the two layers of powder A and powder B at the interface through the viscous epoxy resin, naturally forming a gradient transition zone of components and pores, rather than a sharp interface. After holding the pressure for 180 seconds, the mold is opened and the product is removed after appropriate cooling.

[0098] Example 4

[0099] Powder preparation:

[0100] Powder A: 20% flake graphite with an average particle size of 40 micrometers, 45% expanded graphite with an average particle size of 80 mesh, and powder with an average particle size of 10 μm and a specific surface area of ​​800 m². 2 The mixture consists of graphene (10%), conductive carbon black (8%) with an average particle size of 1 μm, short-cut carbon fibers (7%) with a length of 3 mm and an average diameter of 7 μm, PE emulsion (5%) with a PE content of 15 wt%, and epoxy resin E51 (5%).

[0101] Powder B is obtained by mixing flake graphite (55%) with an average particle size of 50 micrometers, spherical graphite (15%) with an average particle size of 7 micrometers, mesophase pitch-based carbon fiber (5%), epoxy resin E51 (20%), and sulfonated polyarylether ketone (5%).

[0102] Powder spreading and pre-compression process parameters

[0103] The total depth of the mold cavity of the flat mold is 12mm. The hydraulic cylinder ejects the mold core, leaving a 7mm mold cavity volume. After A powder is applied, the hydraulic cylinder is pulled down to the bottom, leaving a 5mm mold cavity volume. After B powder is applied, pre-compression is performed with a pressure of 10MPa.

[0104] Molding and curing:

[0105] A stepped pressurization method is used. First, the mold is closed and the pressure is increased to 10 MPa. Then, the temperature is raised to 180°C, and the pressure is slowly increased to 50 MPa. This promotes the interpenetration and diffusion of the two layers of powder A and powder B at the interface through the viscous epoxy resin, naturally forming a gradient transition zone of components and pores, rather than a sharp interface. After holding the pressure for 180 seconds, the mold is opened and the product is removed after appropriate cooling.

[0106] Comparative Example 1

[0107] Powder preparation:

[0108] Powder A: 15% flake graphite with an average particle size of 35 micrometers, 40% expanded graphite with an average particle size of 80 mesh, and powder with an average particle size of 10 μm and a specific surface area of ​​800 m². 2 The mixture consists of graphene (15%), conductive carbon black (8%) with an average particle size of 1 μm, short-cut carbon fibers (7%) with a length of 3 mm and an average diameter of 7 μm, PE emulsion (5%) with a PE content of 15 wt%, and epoxy resin E51 (10%).

[0109] Powder spreading and pre-compression process parameters

[0110] The total depth of the mold cavity of the flat mold is 12mm. The mold core is ejected by the hydraulic cylinder, leaving a 7mm mold cavity volume. After the A powder is spread, pre-compression is performed with a pressure of 10MPa.

[0111] Molding and curing:

[0112] A stepped pressurization method is used. First, the mold is closed and the pressure is increased to 10 MPa. Then, the temperature is raised to 180°C, and the pressure is slowly increased to 50 MPa. After holding the pressure for 180 seconds, the mold is opened and the product is removed after appropriate cooling.

[0113] Comparative Example 2

[0114] Powder preparation:

[0115] Powder B is obtained by mixing flake graphite (55%) with an average particle size of 50 micrometers, spherical graphite (15%) with an average particle size of 7 micrometers, mesophase pitch-based carbon fiber (5%), epoxy resin E51 (20%), and sulfonated polyarylether ketone (5%).

[0116] Powder spreading and pre-compression process parameters

[0117] The total depth of the mold cavity of the flat mold is 12mm. The mold core is ejected by the hydraulic cylinder, leaving a 7mm mold cavity volume. After B powder is applied, pre-compression is carried out with a pressure of 10MPa.

[0118] Molding and curing:

[0119] A stepped pressurization method is used. First, the mold is closed and the pressure is increased to 10 MPa. Then, the temperature is raised to 180°C, and the pressure is slowly increased to 50 MPa. After holding the pressure for 180 seconds, the mold is opened and the product is removed after appropriate cooling.

[0120] The methods for representing data are as follows:

[0121] 1. SEM-EDS scanning: SEM images of the sample cross-section were taken to observe the continuous changes in pore size and morphology from side A to side B, and the state of pure materials A and B.

[0122] 2. Air tightness test: Comparison of air tightness of bipolar plates made of three materials: mixture AB, material A, and material B. The test method is differential pressure method, with an air pressure of 0.5 bar.

[0123] 3. Contact angle test: Measure the water contact angle of the A and B sides of the sample to verify the hydrophobic and hydrophilic properties.

[0124] 4. In-plane resistance measurement: The four-point probe method is used to verify the extremely high conductivity of side B and the smooth change when transitioning to side A.

[0125] 5. Thermal conductivity measurement: The thermal conductivity of bipolar plates made of three materials, namely mixture A and material B, was compared using the laser flash method.

[0126] The specific test results are as follows:

[0127]

[0128] As can be seen from the table above, the bipolar plates prepared in Examples 1-4 maintain the porous nature of the hydrophilic side while having an overall airtightness close to that of the bipolar plates prepared from the dense pure B material (Comparative Example 2). This indicates that the dense structure on the hydrophilic side forms an effective barrier in the thickness direction.

[0129] As can be seen from the contact angle data in the table above, the method provided by this invention successfully prepared a bipolar plate that is hydrophobic on one side and hydrophilic on the other, which is beneficial for differentiated water management on both sides of the bipolar plate. At the same time, it also avoids the exchange of substances between the water on both sides of the bipolar plate.

[0130] The resistivity of the bipolar plate prepared by this invention exhibits a gradient transition without abrupt changes, and its conductivity is comparable to that of the bipolar plate prepared from pure B material (Comparative Example 2), with superior overall performance.

[0131] The bipolar plate prepared by this invention has an optimized heat transport path, and its total thermal conductivity is significantly higher than that of the bipolar plate prepared from pure material A (Comparative Example 2). This demonstrates that the new water side and the hydrophobic side of the bipolar plate prepared by this invention achieve a synergistic effect in thermal management.

Claims

1. A method for preparing a bipolar plate, characterized in that: Includes the following steps: Flake graphite, expanded graphite, graphene, conductive carbon black, chopped carbon fibers, hydrophobic agent and resin are mixed to obtain powder A; Flake graphite, spherical graphite, high thermal conductivity carbon fiber, resin and hydrophilic additives are mixed to obtain powder B; After spreading powder A in the mold, powder B is spread in the mold, or powder B is spread in the mold and then powder A is spread in the mold. The mixture is pre-pressed, then heated to cure the resin, and finally pressed to obtain the final product.

2. The method for preparing a bipolar plate as described in claim 1, characterized in that: In the powder A, the proportion of flake graphite is 10-20 wt%; In the powder A, the proportion of expanded graphite is 40-45 wt%; In the A powder, the proportion of graphene is 10-20 wt%; In the A powder, the proportion of conductive carbon black is 5-10 wt%; In the powder A, the proportion of short-cut carbon fibers is 5-10 wt%. In the powder A, the proportion of hydrophobic agent is 5-10 wt%; In the powder A, the resin accounts for 5-10 wt%.

3. The method for preparing a bipolar plate as described in claim 1, characterized in that: In the B powder, the proportion of flake graphite is 50-55 wt%; In the B powder, the proportion of spherical graphite is 5-20 wt%. In the B powder, the proportion of high thermal conductivity carbon fiber is 5-20 wt%. In the B powder, the resin accounts for 15-20 wt%; In the B powder, the proportion of hydrophilic additives is 5-10 wt%.

4. The method for preparing a bipolar plate as described in claim 1, characterized in that: The resin includes thermosetting resins; The thermosetting resin includes phenolic resin or epoxy resin; The phenolic resin includes WL6012 or MF1; The epoxy resin includes E51, E44, or AG80.

5. The method for preparing a bipolar plate as described in claim 1, characterized in that: The hydrophobic agent includes PE emulsion; The PE content in the PE emulsion is 15-20 wt%. The hydrophilic additives include sulfonated polyarylether ketones.

6. The method for preparing a bipolar plate as described in claim 1, characterized in that: The pre-compression pressure is 8-12 MPa; The pressing pressure is 50-55 MPa; The pressing time is 180-200 seconds.

7. The method for preparing a bipolar plate as described in claim 1, characterized in that: In the powder A, the average particle size of the flake graphite is 35-40 μm; In the powder A, the average particle size of the expanded graphite is 80 mesh; In the A powder, the average particle size of graphene is 10 μm, and the specific surface area is 800-850 m². 2 / g; In the A powder, the average particle size of the conductive carbon black is 1-2 μm; In the powder A, the length of the short-cut carbon fiber is 3mm and the diameter is 7-10μm.

8. The method for preparing a bipolar plate as described in claim 1, characterized in that: In the B powder, the average particle size of the flake graphite is 50-55 μm; In the B powder, the average particle size of the spherical graphite is 7-8 μm; In the B powder, the high thermal conductivity carbon fiber is selected from mesophase pitch-based carbon fiber.

9. A bipolar plate prepared by the method of claim 1.

10. A fuel cell comprising the bipolar plate as described in claim 9.

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