Bipolar plate and preparation method thereof

Abstract

The present invention relates to a bipolar plate and a method for preparing the same, comprising a base plate, the base plate comprising a three-dimensional honeycomb outer frame structure and an inner layer structure filled in the outer frame structure, the outer frame structure comprising a main frame and a plurality of connected regular polygonal support portions arranged in the main frame, the adjacent sides of each regular polygonal support portion overlapping, the inner layer structure filling the interior of the honeycomb outer frame structure; the material used for the honeycomb outer frame structure comprises a metal material, and the material used for the inner layer structure comprises a graphite material. The present invention prepares the bipolar plate from the aspect of structure establishment in the material integration process, thereby obtaining a bipolar plate with good mechanical properties and strong corrosion resistance. The present invention injects graphite material into the holes and grooves of the honeycomb outer frame structure, and the graphite regions are divided into blocks and formed into a whole, and are supported and fixed to each other in the metal material frame, which effectively improves the mechanical strength of the base plate of the bipolar plate and solves the problem of graphite fragility.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell bipolar plates, and more particularly to a bipolar plate and a method for preparing the same. Background Art

[0002] Bipolar plates are a crucial component of fuel cells and a major contributor to the quality of the fuel cell stack. As a core component of fuel cells, bipolar plates play a number of important roles, including supporting the membrane electrode structure, separating hydrogen and oxygen, collecting electrons, conducting heat, providing pathways for hydrogen and oxygen, discharging generated water, and providing coolant flow. Therefore, they must possess excellent electrical conductivity, strong corrosion resistance, high mechanical strength, and a lightweight design.

[0003] Depending on the material, bipolar plates can be made of graphite, metal, and so on. Each of the above two materials has its own advantages and disadvantages. In traditional technology, graphite bipolar plates are a more commonly used bipolar plate material. Graphite has better electrical and thermal conductivity and low corrosion resistance, but it has low mechanical strength, is fragile, and is a porous medium with poor airtightness. However, due to the relatively low production cost of metal bipolar plates in mass production, and the fact that high-power metal bipolar plate stacks are much smaller in volume than graphite bipolar plate stacks, the application of metal bipolar plates has become increasingly widespread in recent years. However, metal bipolar plates have drawbacks such as poor corrosion resistance, the need for surface treatment, high processing costs, and instability.

[0004] Composite bipolar plates that combine the above two materials have come into being. Composite bipolar plates are composed of two or more materials, synthesizing other materials to optimize mechanical properties, overcome the defects of graphite materials and metal materials, and combine the corrosion resistance of graphite materials with the high strength characteristics of metal materials. At present, the design of composite bipolar plates is mostly to mix metal materials and graphite materials and then prepare them as a whole, or to simply stack them in the form of coating, and the overall bearing capacity of the structure has not been effectively improved. Summary of the Invention

[0005] In response to the above-mentioned technical problems, a bipolar plate and a method for preparing the same are provided.

[0006] The technical means adopted in the present invention are as follows:

[0007] A bipolar plate includes a base plate, the base plate including a three-dimensional honeycomb outer frame structure and an inner layer structure filled within the outer frame structure, the outer frame structure including a main frame and a plurality of connected regular polygonal support portions arranged in the main frame, the adjacent sides of each regular polygonal support portion overlapping, and the inner layer structure filling the interior of the honeycomb outer frame structure; the material used for the honeycomb outer frame structure includes a metal material, and the material used for the inner layer structure includes a graphite material.

[0008] Furthermore, the height of the regular polygonal holes in the three-dimensional honeycomb outer frame structure is 1-2.5 mm.

[0009] Furthermore, the upper surface of the substrate is coated with a functional coating, and the functional materials in the functional coating include one or more of carbon powder, Pt powder, Pt / C powder, Ti powder, and titanium alloy powder. The thickness of the functional coating is 2-300 nm.

[0010] Furthermore, the metal material is metal powder, which is one or more of spherical dehydrogenated titanium powder, spherical atomized titanium powder, and titanium powder. The particle size of the metal powder is 1-29 μm, and the mass ratio is: spherical dehydrogenated titanium powder, spherical atomized titanium powder, and titanium powder: 0-1:0-3:1; the graphite material includes one or more of graphite, XC-72, and XC-72R.

[0011] The present invention also discloses a method for preparing the bipolar plate, comprising the following steps:

[0012] S1. Configure graphite materials and functional coatings;

[0013] S2, using metal powder to load and using a 3D printer to form an orderly three-dimensional honeycomb frame structure;

[0014] S3, injecting graphite material into the three-dimensional honeycomb outer frame structure of S2 to form an inner layer structure, which forms the initial base plate of the bipolar plate;

[0015] S4, performing a first heating and curing treatment on the initial base plate in S3 to obtain a cured base plate of the bipolar plate;

[0016] S5, after spraying the functional coating on the upper surface of the cured substrate in S4, performing a second heating and curing treatment;

[0017] S6. Surface treatment is performed on the cured substrate after S5.

[0018] Furthermore, the configuration of the graphite material in S1 is as follows: graphite powder and a low-boiling-point alcohol solvent are mixed to form a graphite mixed slurry, wherein the concentration of the graphite material in the graphite mixed slurry is 0.1-20 g / ml;

[0019] The functional coating described in S1 is configured as follows: functional materials and low-boiling-point alcohol solvents are mixed to form a functional slurry, wherein the functional materials account for 0.1-10 g / ml of the functional slurry by mass.

[0020] Furthermore, the 3D printing parameters in S2 are set as follows: power is 200-350W; laser nozzle printing linear speed is 500-800mm / s; laser nozzle printing corner speed is 100-300mm / s; laser nozzle printing idle running speed is 300-600mm / s; laser track spacing is 0.1-0.15mm; powder spreading speed is 10-40mm / s; and printing layer thickness is 20-50μm.

[0021] Furthermore, the graphite material in S3 is realized by ultrasonically assisted powder conveying, and the ultrasonic power is 800-2000W.

[0022] Furthermore, the first curing heating method in S4 is vacuum heating, the temperature is 80-150°C, and the vacuum degree is -0.1-1MPa; the second curing heating method in S5 is normal pressure curing, and the temperature is 40-100°C.

[0023] Furthermore, the surface treatment described in S6 is: first, the cured base plate is cut and separated from the processing platform of the 3D printer, and then the cut surface and non-cut surface of the cured bipolar plate are polished, and the thickness of the polished cured bipolar plate is controlled to be 1-2.5 mm.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The base plate of the bipolar plate of the present invention adopts a honeycomb structure, which has the advantages of low cost and consumables, reduced overall weight, and high structural stability. Secondly, graphite material is injected into the honeycomb structure. On the one hand, the graphite material is still the main material of the bipolar plate. Even if some areas are worn after long-term use, it will not have a significant impact on performance. On the other hand, under the outer frame of the metal material, the graphite material is injected into each regular polygonal hole groove. The graphite areas are divided into blocks and formed into a whole. They are supported and fixed to each other within the metal frame. Therefore, the mechanical strength of the base plate of the bipolar plate is effectively improved and the problem of graphite fragility is solved.

[0026] 2. The present invention adopts a honeycomb structure as the outer frame and injects graphite material. Compared with other structural methods of drilling holes in the integral plate and then injecting other materials, the present invention fully utilizes the strict geometric shape of the honeycomb structure to obtain the maximum volume with the least material. Therefore, after obtaining the structure with the highest fit, the simplest required materials, and the largest available space, the graphite material is injected, which can evenly disperse the external force to improve the overall bearing capacity of the structure. Therefore, the graphite material will not become fragile after injection.

[0027] 3. The present invention uses 3D printing technology to prepare the metal outer frame structure of the base plate, which has the advantage of one-piece molding and can effectively and precisely form irregular shapes such as the shape and structure of the honeycomb;

[0028] 4. When the present invention is applied to a fuel cell system based on a bipolar plate, the bipolar plate is used as the core component, combined with an optimized gas flow path design, to improve the power output and energy density of the overall battery. A highly conductive modified graphite material is introduced to ensure the current transfer efficiency under high load conditions, solving the problem of insufficient conductivity of traditional graphite materials under high power conditions. The honeycomb structure design optimized by fluid mechanics improves gas circulation, reduces pressure loss in the reaction area, and improves reaction efficiency. Ultrasonic injection is introduced during the preparation process to ensure that the graphite slurry is evenly filled into each pore, thereby improving the overall sealing and performance stability of the bipolar plate.

[0029] 5. The bipolar plate of the present invention adopts a honeycomb frame with optimized structure, which takes into account both low material usage and high overall rigidity, thereby reducing the weight of the bipolar plate and improving the energy density of the fuel cell.

[0030] 6. By introducing highly conductive graphite materials, the conductivity of the bipolar plate is significantly improved, enabling it to maintain good electrochemical properties in high-power battery applications, thereby improving battery efficiency and output power.

[0031] 7. The surface modification treatment using functional coating enhances the bonding force between metal and graphite, improves the performance stability of bipolar plates in high temperature and corrosive environments, thereby extending the service life of the product and reducing long-term operation and maintenance costs.

[0032] 8. In the process of conveying graphite powder to the honeycomb structure, ultrasonic vibration is used to assist dispersion, thereby achieving real-time dispersed injection, ensuring the refinement of graphite powder, reducing the risk of bubble formation, helping to enhance the airtightness of the structure, preventing gas leakage, and improving the safety and reliability of the battery system.

[0033] Through the detailed description of the above-mentioned claims expansion, innovative points and beneficial effects, the comprehensive performance and application potential of the present invention are improved, meeting the requirements of modern fuel cell systems for high efficiency, durability and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0035] Figure 1 Schematic top view of the bipolar plate structure;

[0036] Figure 2 Schematic side view of the bipolar plate structure;

[0037] In the figure: 1. Honeycomb outer frame structure; 2. Inner layer structure; 3. Functional coating; 4. Regular polygonal support part; 5. Main frame. DETAILED DESCRIPTION

[0038] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0040] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0041] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​described in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0042] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0043] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0044] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0045] like Figure 1 、 Figure 2 As shown, an embodiment of the present invention discloses a bipolar plate comprising a base plate, the base plate comprising a three-dimensional honeycomb outer frame structure 1 and an inner layer structure 2 filled within the outer frame structure. The outer frame structure comprises a main frame and a plurality of connected regular polygonal support portions 4 disposed within the main frame 5, with adjacent sides of each regular polygonal support portion overlapping. The inner layer structure fills the interior of the honeycomb outer frame structure. The honeycomb outer frame structure is made of a metal material, and the inner layer structure is made of a graphite material. In this embodiment, the regular polygonal support portions of the honeycomb outer frame structure are regular hexagons.

[0046] Furthermore, the height of the regular polygonal slots in the three-dimensional honeycomb outer frame structure is 1-2.5 mm. Taking the regular hexagon in the embodiment of the present invention as an example, the height is the distance between the midpoints of two opposite sides of the regular hexagon.

[0047] Furthermore, the upper surface of the substrate is coated with a functional coating 3. The functional material in the functional coating includes one or more of carbon powder, Pt powder, Pt / C powder, Ti powder, and titanium alloy powder. The thickness of the functional coating is 2-300nm. The final product is a honeycomb outer frame structure filled with graphite. The graphite is flush with the metal frame on the surface, and the functional coating is coated on the upper surface of both. After the substrate is formed, the flow field and the hydrogen and oxygen frame water cavity structures are prepared by etching on the two substrates respectively, and then synthesized together to form a complete bipolar plate.

[0048] Furthermore, the metal material is metal powder, which is one or more of spherical dehydrogenated titanium powder, spherical atomized titanium powder, and titanium powder. The particle size of the metal powder is 1-29 μm, and the mass ratio is: spherical dehydrogenated titanium powder, spherical atomized titanium powder, and titanium powder: 0-1:0-3:1; the graphite material includes one or more of graphite, XC-72, and XC-72R.

[0049] The present invention also discloses a method for preparing the bipolar plate, comprising the following steps:

[0050] S1. Configure graphite materials and functional coatings;

[0051] S2, using metal powder to load and using a 3D printer to form an orderly three-dimensional honeycomb frame structure;

[0052] S3, injecting graphite material into the three-dimensional honeycomb outer frame structure of S2 to form an inner layer structure, which forms the initial base plate of the bipolar plate;

[0053] S4, performing a first heating and curing treatment on the initial base plate in S3 to obtain a cured base plate of the bipolar plate;

[0054] S5, after spraying the functional coating on the upper surface of the cured substrate in S4, performing a second heating and curing treatment;

[0055] S6. Surface treatment is performed on the cured substrate after S5.

[0056] Furthermore, the configuration of the graphite material in S1 is as follows: graphite material and a low-boiling point alcohol solvent are mixed to form a graphite mixed slurry, wherein the concentration of graphite powder in the solution is: 5-40wt%;

[0057] The functional coating in S1 is configured as follows: functional materials and low-boiling-point alcohol solvents are mixed to form a functional slurry, wherein the concentration of the functional materials in the functional slurry is 0.1-2 wt %.

[0058] Furthermore, the 3D printing parameters in S2 are set as follows: power is 200-350W; laser nozzle printing linear speed is 500-800mm / s; laser nozzle printing corner speed is 100-300mm / s; laser nozzle printing idle running speed is 300-600mm / s; laser track spacing is 0.1-0.15mm; powder spreading speed is 10-40mm / s; and printing layer thickness is 20-50μm.

[0059] Furthermore, the graphite material described in S3 is delivered using ultrasonically assisted powder delivery, with an ultrasonic power of 800-2000W. Specifically, in this embodiment, the graphite material is crushed into a powder of a predetermined particle size through ultrasonic pulverization / crushing / atomization, and then blown into the metal frame by a powder delivery device, such as a blower or other powder delivery device. In this embodiment, this step is performed in a 3D printer; in other optional embodiments, this step can also be performed in other devices.

[0060] Furthermore, the first curing heating method in S4 is vacuum heating, the temperature is 80-150°C, and the vacuum degree is -0.1-1MPa; the second curing heating method in S5 is normal pressure curing, and the temperature is 40-100°C.

[0061] Furthermore, the surface treatment described in S6 is: first, the cured base plate is cut and separated from the processing platform of the 3D printer, and then the cut surface and non-cut surface of the cured bipolar plate are polished, and the thickness of the polished cured bipolar plate is controlled to be 1-2.5 mm.

[0062] Example 1

[0063] This embodiment discloses a specific method for preparing a bipolar plate, which includes the following steps:

[0064] S1. Prepare graphite material: 5 g of graphite and 5 ml of ethanol solvent are fully mixed to form a graphite mixed slurry;

[0065] S2: Prepare functional coating: 1g carbon powder, 0.1g Pt powder and 5ml ethanol solvent are fully mixed to form a functional slurry;

[0066] S3. 1 g of spherical dehydrogenated titanium powder with a particle size of 1 μm was loaded into a 3D printer, and a three-dimensional honeycomb outer frame structure was formed by the 3D printer. The 3D printing parameters in this process were set as follows: laser printing power of 200 W; laser nozzle printing linear speed of 500 mm / s; laser nozzle printing corner speed of 100 mm / s; laser nozzle printing running speed of 300 mm / s; laser track spacing of 0.1 mm; powder spreading speed of 10 mm / s; and printing layer thickness of 20 μm.

[0067] S4, injecting the graphite mixed slurry of S1 into the three-dimensional honeycomb outer frame structure of S3 by ultrasonic injection to form an inner layer structure, which forms the initial base plate of the bipolar plate;

[0068] S5, placing the initial bipolar plate in S4 into a heating furnace at 80° C. and a vacuum degree of -0.1 MPa for vacuum heating to complete the first heating and curing treatment, and obtaining a cured base plate of the bipolar plate;

[0069] S6. After the functional coating of S2 is sprayed on the upper surface of the S5 cured substrate by electrostatic spraying, a second heating and curing treatment is performed. The second curing heating method is hot plate normal pressure curing at a temperature of 40°C.

[0070] S7, performing surface treatment on the cured substrate plate after S6, that is, first separating the cured substrate plate from the cutting platform of the SD printer, and then polishing the cut surface and non-cut surface of the cured bipolar plate. The polishing method can be a grinder, sandpaper, etc., and the thickness of the polished cured substrate plate is controlled to be 1 mm;

[0071] S8. Prepare a second base plate using the method of S1-S7, then prepare a flow field structure on the two base plates, and finally overlap and fix the two base plates to form a bipolar plate structure with a thickness of 2 mm.

[0072] Example 2

[0073] A method for preparing a bipolar plate comprises the following steps:

[0074] S1. Prepare graphite material: 10g of XC-72 and 50ml of methanol-based solvent are fully mixed to form a graphite mixed slurry;

[0075] S2: Prepare functional coating: 5g of Pt / C powder, 5g of Ti powder and 50ml of alcohol solvent are mixed to form a functional slurry with a concentration of 15%;

[0076] S3. 20 g of titanium powder with a particle size of 15 μm was loaded into a 3D printer, and a three-dimensional honeycomb frame structure was formed by the 3D printer. The 3D printing parameters in this process were set as follows: laser printing power of 275 W; laser nozzle printing linear speed of 650 mm / s; laser nozzle printing corner speed of 200 mm / s; laser nozzle printing idle speed of 450 mm / s; laser track spacing of 0.125 mm; powder spreading speed of 25 mm / s; and printing layer thickness of 35 μm.

[0077] S4, injecting the graphite mixed slurry of S1 into the three-dimensional honeycomb outer frame structure of S3 by ultrasonic injection to form an inner layer structure, which forms the initial base plate of the bipolar plate;

[0078] S5, placing the initial bipolar plate in S4 into a heating furnace at 115° C. and a vacuum degree of 0.45 MPa for vacuum heating to complete the first heating and curing treatment, and obtaining a cured base plate of the bipolar plate;

[0079] S6. After the functional coating of S2 is sprayed on the upper surface of the substrate cured in S5 by electrostatic spraying, a second heating and curing treatment is performed. The second curing heating method is hot plate normal pressure curing at a temperature of 70°C.

[0080] S7, performing surface treatment on the cured substrate plate after S6, that is, first separating the cured substrate plate from the cutting platform of the SD printer, and then polishing the cut surface and non-cut surface of the cured bipolar plate. The polishing method can be a grinder, sandpaper, etc., and the thickness of the cured substrate plate after polishing is controlled to be 1.75 mm;

[0081] S8. Prepare a second base plate using the method of S1-S7, then prepare a flow field structure on the two base plates, and finally overlap and fix the two base plates to form a bipolar plate structure with a total thickness of 3 mm.

[0082] Example 3

[0083] A method for preparing a bipolar plate comprises the following steps:

[0084] S1. Prepare graphite material: 100 g of graphite, 50 g of XC-72R solvent, and 10 mL of isopropyl alcohol and methanol (1:1 mass ratio) are fully mixed to form a graphite mixed slurry;

[0085] S2. Prepare functional coating: 20g titanium alloy powder, 30g Pt powder and 117mL isopropyl alcohol (1ml) are mixed thoroughly to form a functional slurry with a concentration of 30%;

[0086] S3. 80 g of spherical dehydrogenated titanium powder with a particle size of 29 μm and 40 g of titanium powder with a particle size of 29 μm were loaded into a 3D printer to form a three-dimensional honeycomb frame structure. The 3D printing parameters in this process were set as follows: laser printing power of 350 W; laser nozzle printing linear speed of 800 mm / s; laser nozzle printing corner speed of 300 mm / s; laser nozzle printing idle running speed of 600 mm / s; laser track spacing of 0.15 mm; powder spreading speed of 40 mm / s; and printing layer thickness of 50 μm.

[0087] S4, injecting the graphite mixed slurry of S1 into the three-dimensional honeycomb outer frame structure of S3 by ultrasonic injection to form an inner layer structure, which forms the initial base plate of the bipolar plate;

[0088] S5, placing the initial bipolar plate in S4 into a heating furnace at 150° C. and a vacuum degree of 1 MPa for vacuum heating to complete the first heating and curing treatment, and obtaining a cured base plate of the bipolar plate;

[0089] S6, after spraying the functional coating of S2 on the upper surface of the S5 cured substrate by electrostatic spraying, a second heating and curing treatment is performed again. The second curing heating method is hot stage normal pressure curing at a temperature of 100°C;

[0090] S7, performing surface treatment on the cured substrate plate after S6, that is, first separating the cured substrate plate from the cutting platform of the SD printer, and then polishing the cut surface and non-cut surface of the cured bipolar plate. The polishing method can be a grinder, sandpaper, etc., and the thickness of the polished cured substrate plate is controlled to be 2.5 mm;

[0091] S8. Prepare a second base plate using the method of S1-S7, then prepare a flow field structure on the two base plates, and finally overlap and fix the two base plates to form a bipolar plate structure with a total thickness of 5 mm.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bipolar plate, characterized in that: The invention comprises a base plate, the base plate comprising a three-dimensional honeycomb outer frame structure and an inner layer structure filled in the outer frame structure, the outer frame structure comprising a main frame and a plurality of connected regular polygonal support parts arranged in the main frame, the adjacent sides of each regular polygonal support part overlapping, and the inner layer structure filling the interior of the honeycomb outer frame structure; the material used for the honeycomb outer frame structure comprises a metal material, and the material used for the inner layer structure comprises a graphite material; The preparation method comprises the following steps: S1. Configure graphite materials and functional coatings; S2, using metal powder to load and using a 3D printer to form an orderly three-dimensional honeycomb frame structure; S3, injecting graphite material into the three-dimensional honeycomb outer frame structure of S2 to form an inner layer structure, which forms the initial base plate of the bipolar plate; S4, performing a first heating and curing treatment on the initial base plate in S3 to obtain a cured base plate of the bipolar plate; S5, after spraying the functional coating on the upper surface of the cured substrate in S4, performing a second heating and curing treatment; S6. Surface treatment is performed on the cured substrate after S5.

2. The bipolar plate according to claim 1, characterized in that The height of the regular polygonal slots in the honeycomb outer frame structure is 1-2.5 mm.

3. The bipolar plate according to claim 1, characterized in that The upper surface of the substrate is coated with a functional coating, wherein the functional material in the functional coating includes one or more of carbon powder, Pt powder, Pt / C powder, Ti powder, and titanium alloy powder, and the thickness of the functional coating is 2-300 nm.

4. The bipolar plate according to claim 1, characterized in that The metal material is metal powder, which is one or more of spherical dehydrogenated titanium powder, spherical atomized titanium powder, and titanium powder. The particle size of the metal powder is 1-29 μm, and the mass ratio is: spherical dehydrogenated titanium powder, spherical atomized titanium powder, and titanium powder: 0-1:0-3:1; the graphite material includes one or more of graphite, XC-72, and XC-72R.

5. The bipolar plate according to claim 1, wherein: The configuration of the graphite material in S1 is as follows: a graphite material and a low-boiling-point alcohol solvent are mixed to form a graphite mixed slurry, wherein the concentration of the graphite material in the graphite mixed slurry is 0.1-20 g / ml; The functional coating in S1 is configured as follows: functional materials and low-boiling-point alcohol solvents are mixed to form a functional slurry, wherein the carbon powder accounts for 0.1-10 g / ml of the functional slurry by mass.

6. The bipolar plate according to claim 1, wherein: The 3D printing parameters in S2 are set as follows: power of 200-350W; laser nozzle printing linear speed of 500-800mm / s; laser nozzle printing corner speed of 100-300 mm / s; laser nozzle printing idle speed of 300-600mm / s; laser track spacing of 0.1-0.15mm; powder spreading speed of 10-40mm / s; and printing layer thickness of 20-50μm.

7. The bipolar plate according to claim 1, characterized in that: The graphite material described in S3 is realized by ultrasonic-assisted powder conveying, and the ultrasonic power is 800-2000W.

8. The bipolar plate according to claim 1, wherein: The first curing heating method in S4 is vacuum heating, the temperature is 80-150°C, and the vacuum degree is -0.1-1MPa; the second curing heating method in S5 is normal pressure curing, and the temperature is 40-100°C.

9. The bipolar plate according to claim 1, characterized in that: The surface treatment described in S6 is: first, the cured base plate is cut and separated from the processing platform of the 3D printer, and then the cut surface and the non-cut surface of the cured bipolar plate are polished, and the thickness of the polished cured bipolar plate is controlled to be 1-2.5 mm.

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