Bipolar plate and preparation method thereof

Abstract

The invention relates to a bipolar plate and a preparation method thereof.The bipolar plate comprises a base plate, the base plate comprises a three-dimensional honeycomb type outer frame structure and an inner layer structure filled in the outer frame structure, the outer frame structure comprises a main frame and a plurality of connected regular polygon supporting parts arranged in the main frame, the adjacent edges of the regular polygon supporting parts coincide, and the inner layer structure is arranged between the main frame and the inner layer structure. The honeycomb type outer frame structure is filled with the inner layer structure; the honeycomb type outer frame structure is made of metal materials, and the inner layer structure is made of graphite materials. The bipolar plate is prepared from the aspect of structure establishment in the material integration process, so that the bipolar plate with relatively good mechanical property and relatively high corrosion resistance is obtained. According to the bipolar plate base plate, the graphite material is injected into the hole grooves of the honeycomb type outer frame structure, the graphite area is divided into blocks and forms a whole, and the blocks and the whole are mutually supported and fixed in the metal material frame, so that the mechanical strength of the bipolar plate base plate is effectively improved, and the problem that graphite is fragile is also solved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell bipolar plates, and in particular to a bipolar plate and a preparation method thereof. Background Art

[0002] Bipolar plates are important components of fuel cells and are the main component of the fuel cell stack quality. As the core component of fuel cells, bipolar plates play many important roles in fuel cells, including supporting the membrane electrode structure, separating hydrogen and oxygen, collecting electrons, conducting heat, providing hydrogen and oxygen channels, discharging water generated by the reaction, and providing coolant channels. Therefore, they need to have good electrical conductivity, strong corrosion resistance, high mechanical strength, and light weight.

[0003] Depending on the material, the bipolar plate includes graphite, metal, etc. The bipolar plates of the above two materials have their own advantages and disadvantages. In traditional technology, graphite bipolar plates are the most commonly used bipolar plate materials. Graphite has better electrical and thermal conductivity and low corrosion resistance, but its mechanical strength is low, it is fragile, and it is a porous medium with poor air tightness. However, due to the relatively low production cost of metal bipolar plates in mass production, and at the same time, high-power metal bipolar plate stacks are much smaller in volume than graphite bipolar plate stacks, so in recent years, metal bipolar plates have been increasingly used. However, metal bipolar plates have defects 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 more than two materials, synthesizing other materials, optimizing mechanical properties, overcoming the defects of graphite materials and metal materials, and combining the corrosion resistance of graphite materials with the high strength characteristics of metal materials. Currently, most designs for composite bipolar plates are to mix metal materials and graphite materials and then prepare them as a whole, or to simply stack them in a coating manner, 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 by the present invention are as follows:

[0007] A bipolar plate includes a base plate, wherein the base plate includes a three-dimensional honeycomb outer frame structure and an inner layer structure filled in the outer frame structure, wherein the outer frame structure includes a main frame and a plurality of connected regular polygonal support parts arranged in the main frame, and the adjacent sides of the regular polygonal support parts overlap, and the inner layer structure is filled in 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, 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 2-300nm.

[0010] Furthermore, the metal material is a 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 feed, 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 is the initial base plate of the bipolar plate;

[0015] S4, performing a first heating and curing treatment on the initial substrate plate of S3 to obtain a cured substrate 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] Further, the configuration of the graphite material in S1 is: graphite powder and a low-boiling point alcohol solvent are mixed to form a graphite mixed slurry, and the concentration of the graphite material in the graphite mixed slurry is: 0.1-20g / 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 parameters of 3D printing 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 empty running speed is 300-600mm / s; laser track spacing is 0.1-0.15mm; powder spreading speed is 10-40mm / s; printing layer thickness is 20-50μm.

[0021] Furthermore, the graphite material in S3 is realized by ultrasonic 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: firstly separating the cured base plate from the processing platform of the 3D printer by cutting, then grinding the cut surface and non-cut surface of the cured bipolar plate, and controlling the thickness of the cured bipolar plate after grinding 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 used as the main material of the bipolar plate. Even if there is partial regional wear after long-term use, it will not have a significant performance impact; on the other hand, under the construction of the outer frame of the metal material, the graphite material is injected into each regular polygonal hole groove, and the graphite area is divided into blocks and formed into a whole, and is supported and fixed to each other in the metal material frame, thereby effectively improving the mechanical strength of the base plate of the bipolar plate and solving the problem of graphite fragility;

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

[0027] 3. The present invention adopts 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. After 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. Highly conductive modified graphite materials are 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 method is introduced in the preparation process to ensure that the graphite slurry is evenly filled into each hole and groove, 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 and 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 drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative labor.

[0035] Figure 1 is a top view schematic diagram of the bipolar plate layer structure;

[0036] Figure 2 is a side view schematic diagram of the bipolar plate layer 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 of the present invention and the features in the embodiments 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 by no means 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 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 exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates 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 described in these embodiments, the numerical expressions and numerical values ​​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 technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0042] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the 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 contours 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 here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. 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 figure. For example, if the device in the accompanying 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. If not 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, including a base plate, the base plate including a three-dimensional honeycomb outer frame structure 1 and an inner layer structure 2 filled in the outer frame structure, the outer frame structure including a main frame and a plurality of connected regular polygonal support parts 4 arranged in the main frame 5, the adjacent sides of each regular polygonal support part overlap, and the inner layer structure is filled in 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. In this embodiment, the regular polygonal support part of the honeycomb outer frame structure is a regular hexagon.

[0046] Furthermore, the height of the regular polygonal hole groove 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 plate is coated with a functional coating 3, and 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 2-300nm. The final product is a honeycomb 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 the two. After the substrate plate is formed, the flow field and the hydrogen and oxygen frame water cavity and other structures are prepared by etching on the two substrate plates, and then synthesized together to form a complete bipolar plate.

[0048] Furthermore, the metal material is a 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 feed, 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 is the initial base plate of the bipolar plate;

[0053] S4, performing a first heating and curing treatment on the initial substrate plate of S3 to obtain a cured substrate 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] Further, the configuration of the graphite material in S1 is: taking the graphite material and the low boiling point alcohol solvent to mix and form a graphite mixed slurry, wherein the concentration of the 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 parameters of 3D printing 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 empty running speed is 300-600mm / s; laser track spacing is 0.1-0.15mm; powder spreading speed is 10-40mm / s; printing layer thickness is 20-50μm.

[0059] Furthermore, the graphite material described in S3 is realized by ultrasonic assisted powder delivery, and the ultrasonic power is 800-2000W. Specifically, in this embodiment, the graphite material is crushed into powder of a preset particle size by ultrasonic crushing / crushing / atomization and the like, and then filled into the metal frame by a powder feeding device, such as a blower or other powder feeding device. In this embodiment, this step is completed in a 3D printer, and in other optional embodiments, this step can also be completed 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: firstly separating the cured base plate from the processing platform of the 3D printer by cutting, then grinding the cut surface and non-cut surface of the cured bipolar plate, and controlling the thickness of the cured bipolar plate after grinding to be 1-2.5 mm.

[0062] Example 1

[0063] This embodiment discloses a specific method for preparing a bipolar plate, comprising 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 functional slurry;

[0066] S3, take 1g of spherical dehydrogenated titanium powder with a particle size of 1μm and feed it into the 3D printer, and form a three-dimensional honeycomb frame structure through the 3D printer. In this process, the parameters of 3D printing are set as follows: laser printing power is 200W; laser nozzle printing linear speed is 500mm / s; laser nozzle printing corner speed is 100mm / s; laser nozzle printing empty running speed is 300mm / s; laser track spacing is 0.1mm; powder spreading speed is 10mm / s; printing layer thickness is 20μm;

[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, at this time forming the initial base plate of the bipolar plate;

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

[0069] S6, spraying the functional coating of S2 on the upper surface of the S5 cured substrate by electrostatic spraying, and then performing a second heating and curing treatment, the second curing heating method is hot stage normal pressure curing, the temperature is 40°C;

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

[0071] S8. Prepare a second substrate plate using the method of S1-S7, then prepare a flow field structure on the two substrate plates, and finally overlap and fix the two substrate 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: 10 g of XC-72 and 50 ml of methanol-alcohol solvent are fully mixed to form a graphite mixed slurry;

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

[0076] S3, take 20g of titanium powder with a particle size of 15μm and feed it into the 3D printer, and form a three-dimensional honeycomb frame structure through the 3D printer. In this process, the parameters of 3D printing are set as follows: laser printing power is 275W; laser nozzle printing linear speed is 650mm / s; laser nozzle printing corner speed is 200mm / s; laser nozzle printing empty running speed is 450mm / s; laser track spacing is 0.125mm; powder spreading speed is 25mm / s; printing layer thickness is 35μm;

[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, at this time forming the initial base plate of the bipolar plate;

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

[0079] S6, spraying the functional coating of S2 on the upper surface of the S5 cured substrate by electrostatic spraying, and then performing a second heating and curing treatment, the second curing heating method is hot stage normal pressure curing, the temperature is 70°C;

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

[0081] S8. Prepare a second substrate plate using the method of S1-S7, then prepare a flow field structure on the two substrate plates, and finally overlap and fix the two substrate 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 isopropanol and methanol (1:1 mass ratio) are fully mixed to form a graphite mixed slurry;

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

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

[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, at this time forming the initial base plate of the bipolar plate;

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

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

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

[0091] S8. Prepare a second substrate plate using the method of S1-S7, then prepare a flow field structure on the two substrate plates, and finally overlap and fix the two substrate 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned 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: It comprises a base plate, the base plate comprises a three-dimensional honeycomb outer frame structure and an inner layer structure filled in the outer frame structure, the outer frame structure comprises 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 overlap, and the inner layer structure fills 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.

2. The bipolar plate according to claim 1, characterized in that: The height of the regular polygonal holes in the three-dimensional 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, and 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.

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 present invention also discloses a method for preparing the bipolar plate according to any one of claims 1 to 4, characterized in that: The steps include: S1. Configure graphite materials and functional coatings; S2, using metal powder to feed, 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 is the initial base plate of the bipolar plate; S4, performing a first heating and curing treatment on the initial substrate plate of S3 to obtain a cured substrate 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.

6. The preparation method according to claim 5, characterized in that: The configuration of the graphite material in S1 is: mixing the graphite material and a low-boiling point alcohol solvent 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 described 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 mass fraction of the functional slurry.

7. The preparation method according to claim 5, characterized in that: The parameters of 3D printing 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 empty running speed is 300-600mm / s; laser track spacing is 0.1-0.15mm; powder spreading speed is 10-40mm / s; printing layer thickness is 20-50μm.

8. The preparation method according to claim 5, characterized in that: The graphite material described in S3 is realized by ultrasonic assisted powder conveying, and the ultrasonic power is 800-2000W.

9. The preparation method according to claim 5, characterized in that: 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.

10. The preparation method according to claim 5, characterized in that: The surface treatment described in S6 is: firstly, 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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