An integrated PEM water electrolysis metal bipolar plate and its preparation method

Abstract

The present invention discloses an integrated PEM water electrolysis metal bipolar plate and a preparation method thereof, belonging to the field of hydrogen production by water electrolysis. The bipolar plate includes a substrate, and a microporous titanium layer and a functional coating are sequentially arranged on the surface of the substrate; the functional coating forms the flow channel ridge, the turbulator post and the hydrogen-oxygen frame of the bipolar plate; the pore diameter of the microporous titanium layer is 100 nm - 10 μm; the microporous titanium layer contains spherical dehydrogenated titanium powder; the functional coating contains spherical atomized titanium powder, and the bipolar plate has the advantages of low cost and high corrosion resistance and electrical conductivity.

Description

Technical Field

[0001] The present invention belongs to the field of hydrogen production by electrolysis of water, and particularly relates to an integrated PEM water electrolysis metal bipolar plate and a preparation method thereof. Background Art

[0002] As a clean energy source, hydrogen is becoming increasingly popular. PEM water electrolysis technology can obtain hydrogen by utilizing the excess energy generated by wind energy and solar energy. Proton exchange membrane water electrolysis has many advantages. The only raw material in this process is water, and the products are oxygen and hydrogen. The resulting gases are of high purity, safe, efficient, and environmentally friendly, and can achieve on-site hydrogen production, solving the problem of hydrogen transportation. Therefore, proton exchange membrane water electrolysis technology has important applications in the fields of energy, transportation, chemical industry, etc.

[0003] The bipolar plate is one of the key technologies of proton exchange membrane water electrolysis technology. The bipolar plate has flow channel ridges, a turbulence zone containing turbulence posts, a hydrogen-oxygen frame, and a bridging zone. In addition, the bipolar plate also includes flow channel grooves and hydrogen-oxygen cavities; the flow channel ridges, flow channel grooves, hydrogen-oxygen frame, turbulence posts, and bridging zone form the flow field structure of the bipolar plate. It has the functions of support, gas isolation, conduction, and heat dissipation in the water electrolysis cell. Therefore, there are high requirements for the mechanical properties, conductivity, thermal conductivity, chemical stability, and cost of the bipolar plate material. It is of great significance to study bipolar plates with low cost, high chemical stability, and high conductivity.

[0004] There are three commonly used bipolar plate materials: graphite materials, composite materials, and metal materials. Graphite materials are inexpensive and have a simple processing technology, but the mechanical properties of graphite are poor and it is easy to break under high pressure; composite materials have good chemical stability, but their conductivity, electrothermal, and mechanical properties are poor; metal materials have excellent electrical conductivity, thermal conductivity, and mechanical properties, but due to the requirements for stability, the price of metal materials has become the main limiting factor. In the application process of water electrolysis, the operating conditions of the bipolar plate are much more demanding than those of fuel cells, such as high pressure and fluctuating states. Conventional stainless steel plates are difficult to meet its operating requirements, and corrosion is likely to occur. Moreover, the conductivity of stainless steel plates is poor, and a large amount of energy consumption will be caused during operation. Therefore, conventional water electrolysis materials generally use plates with strong corrosion resistance and electrical conductivity, such as titanium. However, directly using pure titanium plates to prepare bipolar plates will increase the cost of water electrolysis applications. Therefore, it is very important to study how to use low-cost stainless steel metal materials and improve their corrosion resistance and conductivity.

[0005] Traditional water electrolysis bipolar plates include a hydrogen frame, an oxygen frame, and a separator plate. During manufacturing, multiple complex processes such as positioning, gluing, hot pressing, and welding are required. For example, in patent CN 104716329 B, each component of the bipolar plate is first processed separately; then the separator plate is subjected to conductive treatment; finally, after being fixed and formed, it is welded into a complete bipolar plate. Due to the harsh operating conditions of water electrolysis bipolar plates, the materials of water electrolysis bipolar plates need to use titanium or other corrosion-resistant and highly conductive materials, thus greatly increasing the cost. And stainless steel bipolar plates with lower costs, due to their own defects, it is difficult to directly prepare bipolar plates to meet the operating requirements of water electrolysis. Therefore, additional processing of stainless steel plates is required to meet their corrosion resistance requirements. In addition, during operation, the water electrolysis bipolar plate is in direct contact with the membrane electrode to achieve its functions of gas conduction, electricity conduction, and drainage. And how to achieve the balance of the gas conduction, electricity conduction, and drainage performance of the bipolar plate is the key to improving the performance of water electrolysis. Summary of the Invention

[0006] The purpose of the present invention is to provide an integrated PEM water electrolysis metal bipolar plate and its preparation method. Its advantages are that it has low-cost advantages while also having high corrosion resistance and electrical conductivity. The above technical purpose of the present invention is achieved through the following technical solutions:

[0007] The present invention provides a PEM water electrolysis metal bipolar plate. The bipolar plate includes a substrate, and a microporous titanium layer and a functional coating are sequentially arranged on the surface of the substrate; the functional coating forms the flow field structure of the bipolar plate; the pore diameter of the microporous titanium layer is 100 nm - 10 μm; the microporous titanium layer contains spherical dehydrogenated titanium powder; the functional coating contains spherical atomized titanium powder.

[0008] Further, a hydrophobic layer is provided in the flow channel grooves of the bipolar plate; a hydrophobic layer is provided in other areas of the turbulator region of the bipolar plate except for the turbulator posts.

[0009] Further, the substrate is one of a stainless steel plate body, a titanium-high alloy steel composite plate body, and a metal composite plate body; the metal composite plate body includes two pure titanium layers and one titanium-stainless steel composite layer, and the titanium-stainless steel composite layer is placed between the two pure titanium layers.

[0010] Further, the titanium-high alloy steel composite plate body is composed of titanium particles and high alloy steel particles. The particle sizes of the titanium particles and the high alloy steel particles are the same, between 60 - 80 μm; the weight of the titanium particles accounts for 10 - 15% of the total weight of the titanium-high alloy steel composite plate body; the high alloy steel contains one or more of the alloy elements Ni, Ti, and Mo, and the total alloy element mass content is 10% - 30%;

[0011] The titanium-stainless steel composite layer is composed of titanium particles and stainless steel particles. The particle sizes of the titanium particles and the stainless steel particles are the same, between 60 - 80 μm. The titanium particles account for 10 - 15% of the total weight of the mixed particles in the titanium-stainless steel composite layer. The titanium particles in the pure titanium layer have the same particle size as those in the titanium-stainless steel composite layer, and each of the two pure titanium layers accounts for 10 - 15% of the total weight of the composite plate body.

[0012] Further, the particle size of the spherical atomized titanium powder is 20 - 50 μm. The particle size of the spherical dehydrogenated titanium powder is 30 - 100 μm.

[0013] Further, the stainless steel plate body is one of 304 stainless steel, 316 stainless steel, or 316L stainless steel, with a thickness of 0.5 - 1 mm. The thickness of the titanium-high alloy steel composite plate body or the composite plate body composed of a titanium layer, a titanium-stainless steel composite layer, and a titanium layer is 1 - 5 mm.

[0014] The present invention also provides a method for preparing the PEM water electrolysis metal bipolar plate described above, comprising the following steps:

[0015] (1) Spraying spherical dehydrogenated titanium powder onto the surface of a pretreated substrate by means of plasma spraying to form a microporous titanium layer;

[0016] (2) Preparing a functional mixed slurry, and printing the functional mixed slurry onto the microporous titanium layer by means of die printing to form a flow field structure; the flow field structure described here is a generalized flow field structure, including but not limited to a flow field reaction area (flow channel ridges and flow channel grooves). For example, it also includes the inlet and outlet frames of the bipolar plate, sealing frames, etc. (hydrogen-oxygen frames), a flow field distribution area, a bridging area, or a turbulence area. Those skilled in the art can form various structures by die printing according to actual needs.

[0017] (3) Drying and demolding to obtain a water electrolysis metal bipolar plate.

[0018] Further, after the drying and demolding in step (3), a hydrophobic layer is printed onto other areas of the flow channel grooves and turbulence area of the bipolar plate except for the turbulence columns by means of die printing, and then dried and demolded.

[0019] Further, the conditions for the plasma spraying are: plasma enthalpy is 22 - 50 MJ / kg; spraying speed is 600 - 1000 mm / s; spraying temperature is 150 - 200 °C. The pretreatment method for the substrate is: gradually grinding the substrate, and then polishing and rinsing with clean water.

[0020] Further, the substrate surface is gradually ground with sandpaper having a mesh number of 500 - 1200.

[0021] Further, the base surface is polished step by step with sandpapers of 500, 700, 900, and 1200 mesh.

[0022] Further, the preparation method of the titanium-high alloy steel composite plate body includes: screening titanium particles and high alloy steel particles, controlling their uniform diameter, and performing pretreatment; after mixing the pretreated titanium particles and high alloy steel particles, through selective laser melting (SLM), the mixed particles are melted and recombined to generate a titanium-high alloy steel composite plate.

[0023] Further, the pretreatment includes: respectively putting the screened titanium particles and high alloy steel particles into ultrapure water, performing ultrasonic cleaning, and then putting them into a vacuum drying oven for drying and standby.

[0024] Further, the particle size sieve used for screening includes a multi-layer structure, with the number of layers being 3 - 8, and the layer structure is composed of porous high alloy steel plates with different mesh numbers, with the mesh number being 100 - 200 mesh.

[0025] Further, the process parameters of the selective laser melting technology include: the laser power is 300 - 500 w, and the scanning speed is 2000 - 2500 mm / s.

[0026] Further, the preparation method of the composite plate body composed of a titanium layer, a titanium-stainless steel composite layer, and a titanium layer includes: screening titanium particles and stainless steel particles, controlling their uniform diameter, and performing pretreatment; mixing the titanium particles and stainless steel particles to obtain a titanium-stainless steel composite layer; stacking the pure titanium layer formed by titanium particles, the titanium-stainless steel composite layer, and the pure titanium layer formed by titanium particles in sequence, and through selective laser melting (SLM), the mixed particle layers are melted and recombined to generate a composite plate body composed of a titanium layer, a titanium-stainless steel composite layer, and a titanium layer.

[0027] Further, the pretreatment includes: respectively putting the screened titanium particles and stainless steel particles into ultrapure water, performing ultrasonic cleaning, and then putting them into a vacuum drying oven for drying and standby.

[0028] Further, the particle size sieve used for screening includes a multi-layer structure, with the number of layers being 3 - 8, and the layer structure is composed of porous high alloy steel plates with different mesh numbers, with the mesh number being 100 - 200 mesh.

[0029] Further, the process parameters of the selective laser melting technology include: the laser power is 500 - 800 w, and the scanning speed is 2500 - 3000 mm / s.

[0030] Further, the functional mixed slurry includes: spherical atomized titanium powder with a particle size of 20 - 50 μm, a solvent, a binder, and a plasticizer; the solvent includes at least one of ethanol, toluene, or methanol; the binder includes one or a mixture of two of polyvinyl butyral resin or acrylic resin; the plasticizer includes one or a mixture of two or more of dioctyl phthalate, dibutyl phthalate, or propylene glycol polyester oxalate; the mass ratio between the spherical atomized titanium powder with a particle size of 50 - 100 μm, the solvent, the binder, and the plasticizer is 60 - 80:15 - 35:3 - 4:1 - 2.

[0031] Further, the slurry of the hydrophobic layer includes: fluorinated acetylene black, nano-antimony oxide, and a solvent; the solvent includes at least one of ethanol, toluene, or methanol; the mass ratio of fluorinated acetylene black, nano-antimony oxide, and the solvent is 30 - 40:10 - 20:40 - 60; wherein, the particle size of nano-antimony oxide is 5 - 50 nm; in fluorinated acetylene black, the elemental proportion of fluorine element is 60 - 80 wt%.

[0032] Further, in step (2), the functional mixed slurry is printed onto the microporous titanium layer by means of die printing to form a functional coating including flow channel ridges of bipolar plates, turbulator posts, hydrogen-oxygen frames, etc. The method includes: placing multiple thin tubes parallel and spaced on the surface of the microporous titanium layer, making one end of the thin tubes correspond to the hydrogen-oxygen cavity of the bipolar plate, and the other end of the thin tubes correspond to the turbulator area. Then, place the die parallel to the front surface of the microporous titanium layer, and print the functional mixed slurry along the shape of the die on the microporous titanium layer to form a functional coating with flow channel ridges of bipolar plates, turbulator posts, and hydrogen-oxygen frames, etc.

[0033] The thickness of the die is 0.5 - 1 mm. The height of the corresponding formed functional coating is 0.5 - 1 mm.

[0034] Further, the die includes a hollowed-out area and a closed area. The hollowed-out area allows the functional mixed slurry to pass through to form the flow channel ridges of bipolar plates, turbulator posts, and hydrogen-oxygen frames. The closed area is for shielding the areas of the bipolar plate where no flow field structure needs to be formed to form the flow channel grooves of the bipolar plate, the areas other than the turbulator posts in the turbulator area, and the reserved area of the hydrogen-oxygen cavity. The thin tubes are placed at positions corresponding to the hollowed-out area. After printing is completed, the thin tubes are removed to form a fine pore structure between the hydrogen-oxygen cavity and the turbulator area, which can allow materials to enter and exit.

[0035] Further, the die used for printing the hydrophobic layer includes a structure that shields the flow channel ridges and turbulator posts. Through printing, a hydrophobic layer is printed on the surfaces of the flow channel grooves of the bipolar plate flow field structure and the areas other than the turbulator posts in the turbulator area.

[0036] Further, the substrate printed with the microporous titanium layer is placed in an oven for drying. After drying, the mold and the capillary are taken out. The drying temperature is 100-150°C and the time is 3-5 minutes.

[0037] Further, steps (1)-(2) are completed by a continuous production line with a circular guide rail. Several electrically driven sliders are provided on the circular guide rail, and the substrate is placed on the sliders; a plasma spraying area, a first thickness detection area, a mold printing area, and a second thickness detection area are sequentially arranged on the continuous production line. Both the circular guide rail and the continuous production line are electrically connected to the control system circuit.

[0038] The connection between each step of the present invention can be completed by an automated operation through a robotic arm or a mechanical transmission module; the placement of the capillary is accurately placed through a mechanical module, and the position error is 0.01-0.05 mm.

[0039] The present invention has the following beneficial effects:

[0040] 1. The metal bipolar plate prepared by the present invention performs a layered treatment on the titanium layer, so as to strengthen the binding force between titanium particles while meeting the thickness requirements, and improve the conductivity and durability of the bipolar plate; first, a low-cost substrate material is used, and then a plasma spraying method is used to spray a microporous titanium layer on the surface of the substrate. Since a high temperature that can melt the surface particles is generated during the plasma spraying process, the particles on the surface of the bipolar plate substrate will be bombarded. At this time, titanium particles are sprayed again, which can effectively make the titanium particles penetrate into the surface of the steel. The titanium particles are more densely distributed. First, the binding force between the substrate and the microporous titanium layer is increased, laying a solid foundation layer. Then, a functional coating is printed on the surface of the microporous titanium layer. Due to the presence of micropores in the microporous titanium layer and the influence of the printing pressure, the mutual penetration of titanium particles between the functional coating and the microporous titanium layer can be effectively enhanced, thereby improving the binding force between the two, that is, effectively increasing the binding force between the overall titanium layer and the substrate; that is, the present invention uses the superposition of plasma spraying and mold printing to prepare a titanium layer on a low-cost substrate material, which can effectively improve the conductivity and corrosion resistance of the bipolar plate and meet the operating conditions of water electrolysis.

[0041] 2. In the preparation of the metal bipolar plate of the present invention, it is necessary to prepare the integral titanium layer by plasma spraying first and then printing. Since a customized mold is required for printing the functional coating, that is, limited by the shape formation requirements of the bipolar plate and the structure of the mold, the flow channel ridge part of the bipolar plate corresponds to the hollow area of the customized mold. If the functional coating is printed first, that is, first form high and low ridges and grooves on the surface of the stainless steel plate, and then perform plasma spraying after taking the mold. Since the shape of the plate has been formed, it is impossible to ensure uniform spraying at all angles when spraying the microporous titanium layer at this time, and it is impossible to ensure the consistency of the overall thickness. At the same time, due to the smooth and flat surface of the substrate, directly printing the titanium layer and sintering it cannot ensure the bonding force between the titanium layer and the stainless steel plate, and the formed titanium layer is easy to fall off.

[0042] 3. The present invention forms an integral titanium layer (microporous titanium layer and functional coating) on the substrate by plasma spraying and printing. While improving the conductivity and corrosion resistance of the bipolar plate, it can also integrally prepare the water electrolysis bipolar plate. In the traditional preparation process, the separator and the hydrogen-oxygen frame need to be machined and formed separately, and then assembled and formed by bonding with glue. In this way, due to the presence of glue, the bonding strength and integrity will affect the resistance and airtightness of the bipolar plate.

[0043] The water electrolysis bipolar plate integrally prepared by the present invention directly prepares the flow channel, hydrogen-oxygen cavity and other structures of the bipolar plate on the substrate, and does not require additional processes such as gluing and welding to achieve the sealing of the bipolar plate, which greatly improves the production efficiency and saves costs at the same time.

[0044] 4. The present invention first pre-treats the substrate material by gradually grinding to remove the oxides and other impurities on its surface, improving the conductivity of the plate. After printing the titanium layer, the whole is dried, and the slurry is solidified and formed, which is convenient for the formation of the bipolar plate structure and for taking the mold, preventing deformation, and further strengthening the bipolar plate structure, thereby improving the overall integrity of the bipolar plate.

[0045] 5. The metal bipolar plate of the present invention forms an integral titanium layer on the substrate by superimposing a microporous titanium layer and a functional coating. The slurry of the functional coating contains a binder and a plasticizer, and is mixed with spherical atomized titanium powder, so that the functional coating has good mechanical properties and stability, and the prepared bipolar plate has excellent durability.

[0046] 6. After preparing the titanium layer in the present invention, a customized mold is used to print a hydrophobic agent layer on the groove part of the bipolar plate, which improves the hydrophobicity of the bipolar plate groove. During the operation of water electrolysis, it does not affect the water-gas transmission. At the same time, under the action of the customized mold, the hydrophobic agent will not adhere to the ridge area of the bipolar plate flow field, and it is still a direct contact between the titanium layer and the diffusion layer. The conductivity between the bipolar plate and the diffusion layer will not be reduced due to the improved water-gas transmission. Therefore, the present invention realizes the balance among gas conduction, water drainage, and conductivity of the bipolar plate for water electrolysis, and improves the output performance of water electrolysis.

[0047] 7. Compared with the high-cost pure titanium material selected for conventional bipolar plates for water electrolysis, in the present invention, titanium powder and high-alloy steel particles are recombined by laser melting technology using a sieve with a certain mesh number. The plate body contains a large number of titanium powder particles. Titanium particles have high conductivity and high stability. Therefore, the prepared composite plate body has high conductivity. Moreover, the main component of the composite plate body is still high-alloy steel particles with relatively low prices. Therefore, in addition to high conductivity, it also has a lower preparation cost.

[0048] 8. In the present invention, titanium particles and high-alloy steel particles are formed into a composite plate body through laser melting technology, so that the titanium particles are melted into the high-alloy steel, and the two materials are completely fused to form an integral body, taking into account the stability and conductivity of titanium and saving costs. For the fused plate body, although high-stable titanium particles are doped, it is impossible to ensure that the entire surface of the composite plate body is titanium particles, and there are still a large number of high-alloy steel particles. High-alloy steel particles have instability. To avoid the problem of poor corrosion resistance caused by the direct exposure of steel particles or the penetration of iron elements into the water electrolysis cell during operation, resulting in membrane electrode pollution, the present invention sprays a dense microporous titanium layer on the composite plate body to avoid direct contact between the high-alloy steel and the membrane electrode, ensuring the stability of the plate material and the corrosion resistance of the water electrolysis cell, and improving the service life of the electrolytic cell; at the same time, titanium particles and high-alloy steel particles with the same particle size are mixed, and then a composite plate body is formed through laser melting technology. When the particle sizes are the same, it is beneficial to uniformly mix them in the same proportion or a certain proportion, so that the composition of the prepared composite plate body is uniform, and the strength and stability are consistent in both the plane direction and the thickness direction.

[0049] 9. The present invention adopts a sandwich composite layer of a titanium particle layer, a composite layer formed by mixing titanium particles and stainless steel particles, and a titanium particle layer, and forms a composite plate body through laser melting technology. It takes into account the stability and conductivity of titanium and saves costs, while avoiding the problem of poor corrosion resistance caused by the direct exposure of steel particles or the penetration of iron elements into the water electrolysis cell during operation, resulting in membrane electrode pollution. The advantage of using the same particle size is that it can minimize the mutual penetration of different types of particles into other layers, which is beneficial to the mutual independence of the three-layer composite structure components and the formation of a gradient distribution.

[0050] 10. In the present invention, a continuous production line with a circular guide rail is adopted. Through the intelligent measurement and control of the thickness detection device and the control system, the cyclic transmission of a batch of stainless steel plates on this production line can be realized to achieve continuous preparation. Moreover, according to the design of the circular guide rail, before passing through the oven drying process, without the need to expand the length of the transmission track, the natural cooling of the stainless steel plate after plasma spraying and the natural air drying after die printing can be fully realized, so as to realize the continuous preparation in subsequent multiple spraying and printing processes. In addition, without increasing the number of devices, the cyclic transmission of the stainless steel plate can be completed for preparation, saving costs and effectively avoiding the problem that the un-unified debugging of multiple devices affects the product qualification rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0052] Figure 1 It is a schematic diagram of the overall structure of the customized mold a for the metal bipolar plate in the embodiment of the present invention.

[0053] Figure 2 It is a schematic diagram of the placement position of the thin tube when printing the functional coating.

[0054] Figure 3 It is a schematic diagram of the metal bipolar plate after being printed by the customized mold a.

[0055] Figure 4 It is a schematic diagram of the cross-section of the flow field of the water electrolysis bipolar plate in Example 4.

[0056] Figure 5 It is a schematic diagram of the overall structure of the customized mold b for the water electrolysis bipolar plate in Example 4.

[0057] Figure 6 It is a schematic diagram of the processing process of the composite plate body.

[0058] In the figure: 1, hollow area; 2, closed area; 3, thin tube; 4, hydrogen-oxygen cavity; 5, flow channel groove; 6, flow channel ridge; 7, turbulence area; 8, hydrophobic agent layer; 9, functional coating; 10, microporous titanium layer; 11, substrate; 12, hydrogen-oxygen frame; 13, turbulence column. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0059] The following will further elaborate on the present invention in conjunction with the accompanying drawings.

[0060] Example 1

[0061] Slurry preparation: Weigh 60 g of spherical atomized titanium powder with a particle size of 20 μm (the spherical atomized titanium powder obtained by atomization treatment can be prepared by common methods in the art), 35 g of absolute ethanol, 4 g of polyvinyl butyral resin, and 1 g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for standby.

[0062] Cut a piece of 304 stainless steel with a thickness of 0.5 mm and an area of 20 cm x 10 cm, and polish it step by step with 200 - 500 - mesh sandpaper. Then, put the stainless - steel plate into acetone solution and ultrasonically clean it 3 times, 10 minutes each time. After washing, rinse it with ultrapure water, and then take it out and dry it.

[0063] Put the washed stainless - steel plate on the plasma spraying platform, set the spraying machine conditions as follows: plasma enthalpy is 22 MJ / kg; spraying speed is 600 mm / s; spraying temperature is 150 °C. Spray spherical dehydrogenated titanium powder with a particle size of 30 μm (the spherical dehydrogenated titanium powder obtained by dehydrogenation treatment can be prepared by common methods in the art) onto the stainless - steel surface. Then, place multiple thin tubes parallel and spaced on the surface of the microporous titanium layer 10, with one end of the thin tube 3 corresponding to the hydrogen - oxygen cavity 4 of the bipolar plate and the other end of the thin tube 3 corresponding to the turbulence area 7, as Figure 2 and 4 shown. After that, place the customized mold a parallel to the front surface of the microporous titanium layer 10, and print the mixed slurry along the shape of the mold a on the microporous titanium layer 10 to form the functional coating 9. The customized mold a includes a hollow area 1 and a closed area 2. The hollow area 1 is for the functional mixed slurry to pass through to form the required bipolar - plate flow - field structure, that is, corresponding to the bipolar - plate flow - channel ridge 6, turbulence posts 13, and hydrogen - oxygen frame 12 (the hydrogen - oxygen frame is the peripheral frame of the hydrogen - oxygen cavity 4 and the part of the sealant wire groove that needs to be sealed around the bipolar plate). The closed area 2 is for covering the parts of the bipolar plate where no structure needs to be formed, that is, corresponding to the bipolar - plate flow - channel groove 5, other areas of the turbulence area 7 except the turbulence posts 13, and the reserved area of the hydrogen - oxygen cavity 4 (for hydrogen and oxygen to enter and exit the bipolar plate respectively), as Figure 1 and 3 shown. The above - mentioned thin tube 3 corresponds to the position of the hollow area 1 of the customized mold a for the passage and printing of the functional mixed slurry, and a flow - channel structure for connecting the hydrogen - oxygen cavity 4 with the required materials of the bipolar plate is formed correspondingly during printing, as Figure 2 and 4 shown. The thickness of the customized mold a is 0.3 mm. Then, put it into an oven at 100 °C for heat treatment for 5 minutes. After the time is up, take it out and demold, take out the thin tube 3 and the mold. Finally, use a laser cutting machine to cut to form the hydrogen - oxygen cavity 4, and finally obtain the water - electrolysis bipolar plate.

[0064] As shown in Table 1, the bipolar plates prepared in this embodiment have excellent performance in terms of both contact resistance and corrosion current density. After testing, its contact resistance is only 0.67 mΩ·cm 2 , indicating that the bipolar plate has good output performance, and the corrosion current density is measured to be 3.25 μA / cm 2 , reflecting that the prepared bipolar plate has good durability.

[0065] Example 2

[0066] Slurry preparation: Weigh 70 g of spherical atomized titanium powder with a particle size of 35 μm, 20 g of absolute ethanol, 3.5 g of polyvinyl butyral resin, and 1.5 g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for standby.

[0067] The treatment method of the stainless steel plate substrate is the same as that in Example 1.

[0068] Put the washed stainless steel plate on the plasma spraying platform, set the spraying machine conditions as follows: plasma enthalpy is 36 MJ / kg; spraying speed is 800 mm / s; spraying temperature is 175 °C. Spray spherical dehydrogenated titanium powder with a particle size of 60 μm onto the stainless steel surface. Then place multiple thin tubes 3 parallel and spaced on the surface of the microporous titanium layer 10, with one end of the thin tube 3 corresponding to the hydrogen-oxygen cavity 4 of the bipolar plate and the other end corresponding to the turbulence zone 7, as Figure 2 and 4 shown. After that, place the customized mold a parallel to the front surface of the microporous titanium layer 10, and print the mixed slurry along the shape of the mold a on the microporous titanium layer 10 to form the functional coating 9. The thickness of the customized mold a is 0.4 mm, then put it into an oven at 125 °C for heat treatment for 4 min. After the time is up, take it out and demold. Take out the thin tube 3 and finally use a laser cutting machine to cut to form the hydrogen-oxygen cavity 4, and prepare the water electrolysis bipolar plate.

[0069] As shown in Table 1, the bipolar plates prepared in this embodiment have excellent performance. It can be seen that its contact resistance is only 0.63 mΩ·cm 2 , indicating that after the bipolar plates are stacked, their electrical conductivity with the membrane electrode is excellent and they have good output performance, while the corrosion current density is only 3.57 μA / cm 2 . They have good durability.

[0070] Example 3

[0071] Slurry preparation: Weigh 80 g of spherical atomized titanium powder with a particle size of 50 μm, 15 g of absolute ethanol, 3 g of polyvinyl butyral resin, and 1 g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for standby.

[0072] The stainless steel sheet of this embodiment is 316 stainless steel, and the treatment method of the stainless steel sheet substrate is the same as that of Embodiment 1.

[0073] Put the washed stainless steel plate on the plasma spraying platform, set the spraying machine conditions as follows: plasma enthalpy is 50 MJ / kg; spraying speed is 1000 mm / s; spraying temperature is 200 °C. Spray spherical dehydrogenated titanium powder with a particle size of 100 μm onto the stainless steel surface. Then, place multiple thin tubes 3 parallel and spaced on the surface of the microporous titanium layer 10, with one end of the thin tube 3 corresponding to the hydrogen-oxygen cavity 4 of the bipolar plate and the other end corresponding to the turbulence zone 7, as Figure 2 and 4 shown. After that, place the customized mold a parallel to the front surface of the microporous titanium layer 10, and print the mixed slurry along the shape of the mold a on the microporous titanium layer 10 to form the functional coating 9. The thickness of the customized mold a is 0.5 mm, then put it into an oven at 150 °C for heat treatment for 3 min. After the time is up, take it out and demold, take out the thin tube 3, and finally use a laser cutting machine to cut to form the hydrogen-oxygen cavity 4 to obtain the water electrolysis bipolar plate.

[0074] After testing, the prepared bipolar plate has excellent performance. As shown in Table 1, the contact resistance is 0.64 mΩ·cm 2 , and the corrosion current density is only 3.22 μA / cm 2 .

[0075] In Comparative Example 1, a traditional metal stainless steel plate was directly engraved without a titanium layer

[0076] The treatment method of the stainless steel sheet substrate is the same as that of Embodiment 1.

[0077] Put the treated stainless steel sheet into the milling platform, and use the milling platform to engrave the flow field, material inlet and outlet, sealant wire groove and other areas of the metal bipolar plate. After milling, wash it to obtain the metal stainless steel plate.

[0078] Since the stainless steel plate was not treated and was directly machined by milling to construct the flow field, material inlet and outlet, sealant wire groove and other areas of the bipolar plate, for the plate body itself, it is still a metal stainless steel plate. Therefore, its performance will be relatively poor. After testing, its contact resistance is as high as 7.23 mΩ·cm 2 , and the corrosion current density is 9.87 μA / cm 2 . In the single cell test, at a current density of 1500 mA cm -2 , the voltage is as high as 2.514 V.

[0079] In Comparative Example 2, there is no plasma spraying of the microporous titanium layer, and the flow field is directly printed

[0080] Slurry preparation: Weigh 60 g of spherical atomized titanium powder with a particle size of 20 μm, 35 g of absolute ethanol, 4 g of polyvinyl butyral resin, and 1 g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for standby.

[0081] The treatment method of the stainless steel sheet substrate is the same as that in Example 1.

[0082] Compared with Example 1, plasma-sprayed titanium powder was not used, and the functional coating was directly printed on the surface of the stainless steel sheet.

[0083] Plasma-sprayed titanium powder was not used, and the titanium slurry was directly printed on the surface of the stainless steel plate. The bonding force between the substrate and the coating was poor and it was easy to fall off. In the performance test, its contact resistance was 3.01 mΩ·cm 2 , directly reflecting that the water electrolysis output performance was poor, and its corrosion density was 6.25 μA / cm 2 , and the durability of the electrode plate was poor.

[0084] Table 1 Test results

[0085] Serial number <![CDATA[Contact resistance mΩ·cm 2 > <![CDATA[Corrosion current density μA / cm 2 > Example 1 0.67 3.25 Example 2 0.63 3.57 Example 3 0.64 3.22 Comparative example 1 7.23 9.87 Comparative example 2 3.01 6.25

[0086] Example 4

[0087] Slurry preparation: Weigh 60 g of spherical atomized titanium powder with a particle size of 20 μm, 35 g of absolute ethanol, 4 g of polyvinyl butyral resin, and 1 g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for standby.

[0088] Hydrophobic agent slurry preparation: Weigh 30 g of fluorinated acetylene black with a fluorine element content of 60 wt%, 10 g of nano-antimony oxide with a particle size of 5 nm, and 60 g of absolute ethanol in a beaker and stir evenly for standby.

[0089] The treatment method of the stainless steel sheet substrate is the same as that in Example 1.

[0090] Put the washed stainless-steel plate on the plasma spraying platform, and set the spraying machine conditions as follows: the plasma enthalpy is 22 MJ / kg; the spraying speed is 600 mm / s; the spraying temperature is 150 °C. Spray spherical dehydrogenated titanium powder with a particle size of 30 μm onto the stainless-steel surface. Then, place multiple thin tubes 3 parallel and spaced on the surface of the microporous titanium layer 10, with one end of the thin tube 3 corresponding to the hydrogen-oxygen cavity 4 of the bipolar plate and the other end corresponding to the turbulence zone 7. Next, place the mold a on the surface of the stainless-steel plate on the side sprayed with spherical dehydrogenated titanium powder, and print the slurry onto the surface of the microporous titanium layer 10 according to the shape of the mold a to form the flow field structure of the bipolar plate. The flow field structure includes a flow channel ridge 6, a turbulence post 13, and a hydrogen-oxygen frame 12, with a thickness of 0.3 mm and a micropore diameter of 100 nm. Then, put it into an oven at 100 °C for heat treatment for 5 minutes. After the time is up, take it out and demold, and take out the thin tube 3.

[0091] Place the customized mold b on the surface of the bipolar plate, and then evenly print the hydrophobic agent slurry along the shape of the mold b onto the flow channel grooves 5 of the bipolar plate and other areas of the turbulence zone 7 except the turbulence post 13 to form a hydrophobic agent layer 8. After printing is completed, demold and put the bipolar plate into an oven at 100 °C for heat treatment for 5 minutes. After the time is up, take it out.

[0092] Among them, as Figure 5 shown, the structure of the customized mold b is the same as the bipolar plate structure formed above, which is a flat plate structure. The flow channel grooves 5 of the bipolar plate and other areas of the turbulence zone 7 except the turbulence post 13 in the customized mold b are hollow areas 1, and the rest are closed areas 2, that is, the flow channel ridge 6, the turbulence post 13, and the hydrogen-oxygen frame 12 of the bipolar plate are blocked, so that the hydrophobic agent slurry can be printed on other areas of the flow channel grooves 5 of the bipolar plate and the turbulence zone 7 except the turbulence post 13.

[0093] After testing, the bipolar plate prepared in this embodiment has excellent performance. Its contact resistance is 0.67 mΩ·cm 2 , in terms of the durability test, its corrosion current density is 3.38 μA / cm 2 , in the single-cell test, at a current density of 1500 mA cm -2 , the voltage is only 1.817 V, showing good output performance.

[0094] Example 5

[0095] Slurry preparation: Weigh 70 g of spherical atomized titanium powder with a particle size of 35 μm, 20 g of absolute ethanol, 3.5 g of polyvinyl butyral resin, and 1.5 g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for standby.

[0096] Preparation of hydrophobic agent slurry: Weigh 35 g of fluorinated acetylene black with a fluorine element content of 70 wt%, 15 g of nano-antimony oxide with a particle size of 30 nm, and 55 g of absolute ethanol in a beaker, stir evenly, and set aside.

[0097] The remaining methods are the same as those in Example 4.

[0098] For the bipolar plates prepared in this example and Example 2, assemble them into a single cell to test the pressure difference between the inlet and the outlet. The specific test method is as follows: Seal the bipolar plate with the end plate, connect compressed air at 0.5 MPa to the inlet, connect the outlet to the air and connect a pressure gauge, and test the value of the pressure gauge. The result shows that the pressure gauge in Example 5 shows 0.49 MPa, while the pressure gauge in Example 2 shows 0.38 MPa. This indicates that the pressure drop caused by the bipolar plate in this example during gas transmission is less than that of the bipolar plate prepared in Example 2. By spraying the hydrophobic agent slurry on the surface of the grooves in the flow channels 5 and the turbulence zones 7 of the bipolar plate where gas passes, the balance among gas conduction, water drainage, and electricity conduction of the water electrolysis bipolar plate can be achieved, further improving the output performance of water electrolysis.

[0099] After testing, the contact resistance of the bipolar plate prepared in this example is 0.66 mΩ·cm 2 , and the corrosion current density is 3.39 μA / cm 2 , in the single cell test, at a current density of 1500 mA cm -2 , its voltage is 1.793 V, showing good performance and durability.

[0100] Example 6

[0101] Slurry preparation: Weigh 80 g of spherical atomized titanium powder with a particle size of 50 μm, 15 g of absolute ethanol, 3 g of polyvinyl butyral resin, and 1 g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer, and set aside.

[0102] Preparation of hydrophobic agent slurry: Weigh 35 g of fluorinated acetylene black with a fluorine element content of 70 wt%, 15 g of nano-antimony oxide with a particle size of 30 nm, and 55 g of absolute ethanol in a beaker, stir evenly, and set aside.

[0103] The remaining methods are the same as those in Example 4.

[0104] The bipolar plate prepared in this example also has excellent performance. After testing, the contact resistance of the bipolar plate is 0.67 mΩ·cm 2 , and the corrosion current density is 3.43 μA / cm 2 , in the single cell test, at a current density of 1500 mA cm -2 , its voltage is 1.816 V.

[0105] Comparative Example 3

[0106] Slurry preparation: Weigh 60 g of spherical atomized titanium powder with a particle size of 20 μm, 35 g of absolute ethanol, 4 g of polyvinyl butyral resin, and 1 g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for standby.

[0107] Hydrophobic agent slurry preparation: Weigh 30 g of fluorinated acetylene black with a fluorine element content of 60 wt%, 10 g of nano-antimony oxide with a particle size of 5 nm, and 60 g of absolute ethanol in a beaker, stir evenly, and set aside.

[0108] The treatment method of the stainless steel sheet substrate is the same as that in Example 4.

[0109] Compared with Example 4, first use mold a to print the functional coating 9 on the surface of the stainless steel sheet, then use the plasma spraying method to spray spherical dehydrogenated titanium powder on the surface of the functional coating 9, and finally use mold b to print the hydrophobic layer.

[0110] First print the titanium layer. The bonding force between the titanium layer and the stainless steel plate is poor, and the contact resistance is relatively high, which is 0.68 mΩ·cm 2 , because the titanium layer is printed first, in areas such as the flow field and material inlet and outlet formed, spraying the microporous titanium layer cannot ensure the uniformity of the microporous titanium layer, and the microporous titanium layer cannot be sprayed at its material inlet and outlet because its corrosion current density is relatively large, which is 6.27 μA / cm 2 , at 1500 mA cm -2 Under the current density, its voltage is 2.329 V, and the performance is poor.

[0111] Comparative Example 4

[0112] The method is the same as that in Example 4, except that the hydrophobic agent layer is printed on the entire surface of the substrate.

[0113] When the entire surface of the bipolar plate is hydrophobically treated, the membrane electrode is in direct contact with the back of the bipolar plate. However, when it is too hydrophobic, the conductivity of the bipolar plate is poor. After testing, the contact resistance of the bipolar plate is 3.45 mΩ·cm 2 , the corrosion current density is 5.78 μA / cm 2 , in the single cell test, due to the high contact resistance of the bipolar plate, at 1500 mA cm -2 Under the current density, the voltage is as high as 2.451 V, and the overall performance is poor.

[0114] Table 2 Test results

[0115]

[0116]

[0117] Example 7

[0118] Screen titanium particles with a particle size of 60 μm and high alloy steel particles with a Ni mass content of 10% respectively. Weigh 50 g of the screened titanium particles and 450 g of the high alloy steel particles respectively. Then, ultrasonic clean the two kinds of particles in ultrapure water for 5 min, and after cleaning, put them into a vacuum drying oven for drying. Mechanically mix the dried titanium particles and high alloy steel particles. Using selective laser melting (SLM) technology, put the mixed particles into the laser chamber, adjust the laser power to 300 W and the scanning speed to 2500 mm / s, and melt and recombine the titanium particles and high alloy steel particles to generate a titanium-high alloy steel metal composite sheet. After the material cools, process the plate until the thickness of the sheet is 1 mm.

[0119] Slurry preparation: Weigh 60 g of spherical atomized titanium powder with a particle size of 20 μm, 35 g of absolute ethanol, 4 g of polyvinyl butyral resin, and 1 g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for standby.

[0120] Cut a metal composite sheet with a thickness of 1 mm and an area of 20 cm x 10 cm as the substrate 11, and polish it step by step with 200 - 500 mesh sandpaper. Then, ultrasonic clean the sheet in acetone solution 3 times, 10 min each time. After washing, clean it with ultrapure water, and then take it out and blow it dry.

[0121] Put the washed metal composite sheet on the plasma spraying platform, and set the spraying machine conditions as follows: plasma enthalpy is 22 MJ / kg; spraying speed is 600 mm / s; spraying temperature is 150 °C. Spray spherical dehydrogenated titanium powder with a particle size of 30 μm onto the surface of the metal composite sheet to form a microporous titanium layer 10. Then, place multiple thin tubes 3 parallel and spaced on the surface of the microporous titanium layer 10, with one end of the thin tube 3 corresponding to the hydrogen-oxygen cavity 4 of the bipolar plate and the other end corresponding to the turbulence zone 7, as Figure 2 and 4 shown. After that, place the customized mold a parallel to the front surface of the microporous titanium layer 10, and print the slurry along the shape of the mold on the microporous titanium layer 10 to form a functional coating 9; the thickness of the customized mold a is 0.3 mm, then put it into an oven at 100 °C for heat treatment for 5 min. After the time is up, take it out and demold, and take out the thin tube 3 to prepare a water electrolysis bipolar plate.

[0122] The test results are shown in Table 3. The prepared water electrolysis bipolar plate has excellent output performance and durability, and the contact resistance is only 0.64 mΩ·cm 2 , and the corrosion current density is 3.21 μA / cm 2 .

[0123] Example 8

[0124] Screen titanium particles with a particle size of 70 μm and high alloy steel particles with a Ti mass content of 30% respectively. Weigh 62.5 g of the screened titanium particles and 437.5 g of the high alloy steel particles. Then, ultrasonic clean the two types of particles in ultrapure water for 5 minutes, and after cleaning, put them into a vacuum drying oven for drying. Mechanically mix the dried titanium particles and high alloy steel particles. Using selective laser melting (SLM) technology, put the mixed particles into the laser chamber, adjust the laser power to 400 W and the scanning speed to 2250 mm / s, and melt and recombine the titanium particles and high alloy steel particles to generate a titanium-high alloy steel metal composite plate. When the material cools down, process the material until the plate thickness reaches 1.5 mm.

[0125] Slurry preparation: Weigh 70 g of spherical atomized titanium powder with a particle size of 35 μm, 20 g of anhydrous ethanol, 3.5 g of polyvinyl butyral resin, and 1.5 g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for standby.

[0126] The processing method of the metal composite plate is the same as that in Example 7.

[0127] Put the washed metal composite plate on the plasma spraying platform, set the spraying machine conditions as follows: plasma enthalpy is 36 MJ / kg; spraying speed is 800 mm / s; spraying temperature is 175 °C. Spray spherical dehydrogenated titanium powder with a particle size of 60 μm onto the surface of the metal composite plate to form a microporous titanium layer 10. Then, place multiple thin tubes 3 parallel and spaced on the surface of the microporous titanium layer 10, with one end of the thin tube 3 corresponding to the hydrogen-oxygen chamber 4 of the bipolar plate and the other end corresponding to the turbulent flow area 7. Then, place a customized mold a on the front surface of the microporous titanium layer 10, and print the slurry along the shape of the customized mold a on the microporous titanium layer 10 to form a functional coating 9; the thickness of the customized mold a is 0.4 mm, then put it into an oven at 125 °C for heat treatment for 4 minutes. After the time is up, take it out and demold, and take out the thin tube 3 to prepare a water electrolysis bipolar plate.

[0128] The test results are shown in Table 3. The contact resistance of the prepared bipolar plate is 0.66 mΩ·cm 2 , and the corrosion current density is 3.29 μA / cm 2 . On the basis of using a low-cost high alloy steel material, the bipolar plate still maintains a high performance output, meeting the operating requirements of the water electrolysis bipolar plate.

[0129] Example 9

[0130] Screen titanium particles with a particle size of 80 μm and high alloy steel particles with a Mo alloy content of 30% respectively. Weigh 75 g of the screened titanium particles and 425 g of the high alloy steel particles respectively. Then, ultrasonic clean the two kinds of particles in ultrapure water for 5 min, and put them into a vacuum drying oven for drying after cleaning. Mechanically mix the dried titanium particles and high alloy steel particles. Using selective laser melting (SLM) technology, put the mixed particles into the laser chamber, adjust the laser power to 500 w and the scanning speed to 2000 mm / s, and melt and recombine the titanium particles and high alloy steel particles to generate a titanium-high alloy steel metal composite plate. After the material cools, process the material until the plate thickness is 2 mm.

[0131] Slurry preparation: Weigh 80 g of spherical atomized titanium powder with a particle size of 50 μm, 15 g of absolute ethanol, 3 g of polyvinyl butyral resin, and 1 g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for standby.

[0132] The treatment method of the metal composite plate is the same as that in Example 7.

[0133] Put the washed metal composite plate on the plasma spraying platform, set the spraying machine conditions as follows: plasma enthalpy is 50 MJ / kg; spraying speed is 1000 mm / s; spraying temperature is 200 °C. Spray spherical dehydrogenated titanium powder with a particle size of 100 μm onto the surface of the metal composite plate to form a microporous titanium layer 10. Then, place multiple thin tubes 3 parallel and spaced on the surface of the microporous titanium layer 10, with one end of the thin tube 3 corresponding to the hydrogen-oxygen chamber 4 of the bipolar plate and the other end corresponding to the turbulent flow area 7. Then, place a customized mold a on the front surface of the microporous titanium layer 10, and print the slurry along the shape of the customized mold a on the microporous titanium layer 10 to form a functional coating 9; the thickness of the customized mold a is 0.5 mm. Then, put it into an oven at 150 °C for heat treatment for 3 min. After the time is up, take it out and demold, and take out the thin tube 3 to prepare a water electrolysis bipolar plate.

[0134] The test results are shown in Table 3. The contact resistance of the prepared bipolar plate is 0.63 mΩ·cm 2 , which has high electrical conductivity and is beneficial to improving the electrolysis efficiency of water electrolysis. The bipolar plate current density is 3.19 μA / cm 2 , indicating that the prepared bipolar plate has excellent durability.

[0135] Comparative Example 5

[0136] Replace the metal composite plate in Example 7 with a high alloy steel plate with a Mo alloy content of 30 wt%, and the rest is the same as in Example 7.

[0137] After testing, the contact resistance of the bipolar plate prepared in this comparative example is 0.78 mΩ·cm 2, the corrosion current density is 6.59 μA / cm 2 , compared with Example 1, the performance is poor, which affects the current output of the bipolar plate in the stack.

[0138] Comparative Example 6

[0139] Compared with Example 7, spherical dehydrogenated titanium powder was not used for plasma spraying on the surface of the metal composite sheet. Instead, the slurry was directly printed on the surface of the metal composite sheet by means of die printing, and the remaining steps were the same.

[0140] In this comparative example, although high alloy steel particles and titanium particles were mixed and then melted and recombined, most of the material in the composite sheet was still iron. Printing the titanium layer directly on the prepared sheet without plasma spraying to cover the composite sheet would also result in too large a corrosion current density. Judging from the results, for the bipolar plate prepared in this comparative example, the contact resistance was 1.32 mΩ·cm 2 , and the corrosion current density was as high as 5.98 μA / cm 2 , nearly twice that of 3.21 μA / cm in Example 1 2 .

[0141] Table 3 Test Results

[0142]

[0143]

[0144] Example 10

[0145] Taking the composite plate body composed of a titanium layer, a titanium-stainless steel composite layer, and a titanium layer as the substrate 11, the remaining steps are the same as in Example 7. The composite plate body composed of a titanium layer, a titanium-stainless steel composite layer, and a titanium layer is specifically:

[0146] Titanium particles with a particle size of 60 μm and 304 stainless steel particles were respectively screened. 50 g of the screened titanium particles and 450 g of the 304 stainless steel particles were respectively weighed. Subsequently, the two kinds of particles were put into ultrapure water for ultrasonic cleaning for 5 min, and then put into a vacuum drying oven for drying after cleaning. The dried titanium particles and 304 stainless steel particles were mechanically mixed. 55.6 g of the screened titanium particles were laid flat on the bottom layer of the chamber, then the mixed titanium particle-304 stainless steel particle mixture was laid flat on the bottom titanium particle layer, and finally another layer of titanium particles was laid flat to form a sandwich-like mixed particle layer of titanium particles, titanium particle-stainless steel particle mixture, and titanium particles. Using selective laser melting (SLM) technology, the mixed particle layer was put into the laser chamber, the laser power was adjusted to 300 w, and the scanning speed was 2500 mm / s to melt and recombine the mixed particle layer to generate a composite plate body composed of a titanium layer, a titanium-stainless steel composite layer, and a titanium layer. After the plate body cooled, the plate body was processed until the thickness of the plate body was 1 mm.

[0147] The bipolar plate for water electrolysis prepared by the present invention has good performance. The test results show that the contact resistance between the prepared bipolar plate and the membrane electrode is 0.67 mΩ·cm 2 , and the corrosion current density is 3.15 μA / cm 2 .

[0148] Example 11

[0149] Taking the composite plate body composed of a titanium layer, a titanium-stainless steel composite layer, and a titanium layer as the substrate 11, the remaining steps are the same as those in Example 8. The composite plate body composed of a titanium layer, a titanium-stainless steel composite layer, and a titanium layer is specifically:

[0150] Titanium particles with a particle size of 70 μm and 304 stainless steel particles are respectively screened. 62.5 g of the screened titanium particles and 437.5 g of the 304 stainless steel particles are respectively weighed. Then, the two kinds of particles are put into ultrapure water for ultrasonic cleaning for 5 min, and after cleaning, they are put into a vacuum drying oven for drying. The dried titanium particles and 304 stainless steel particles are mechanically mixed. 71.5 g of the screened titanium particles are spread flat on the bottom layer of the chamber, then the mixed titanium particle-304 stainless steel particle mixture is spread flat on the titanium particle layer at the bottom layer, and finally another layer of titanium particles is spread flat to form a sandwich-like mixed particle layer of titanium particles, titanium particle-stainless steel particle mixture, and titanium particles. Using the selective laser melting technology (SLM), the mixed particle layer is put into the laser chamber, the laser power is adjusted to 400 w, and the scanning speed is 2250 mm / s. The mixed particle layer is remelted and recombined to generate a composite plate body composed of a titanium layer, a titanium-stainless steel composite layer, and a titanium layer. When the plate body cools down, the plate body is processed until the thickness of the plate body is 1.5 mm.

[0151] The bipolar plate for water electrolysis prepared by the present invention has good performance both in terms of electrical conductivity and durability. Although stainless steel particles are used, after the preparation treatment of the present invention, its contact resistance is 0.63 mΩ·cm 2 , and the corrosion current density is 3.21 μA / cm 2 .

[0152] Example 12

[0153] Taking the composite plate body composed of a titanium layer, a titanium-stainless steel composite layer, and a titanium layer as the substrate 11, the remaining steps are the same as those in Example 9. The composite plate body composed of a titanium layer, a titanium-stainless steel composite layer, and a titanium layer is specifically:

[0154] Screen titanium particles with a particle size of 80 μm and 316 stainless steel particles respectively. Weigh 75 g of the screened titanium particles and 425 g of the 316 stainless steel particles respectively. Then, put the two kinds of particles into ultrapure water and perform ultrasonic cleaning for 5 minutes. After cleaning, put them into a vacuum drying oven for drying. Mechanically mix the dried titanium particles and 316 stainless steel particles. Lay 88 g of the screened titanium particles flat on the bottom layer of the chamber, then lay the mixed titanium particle-316 stainless steel particles flat on the titanium particle layer at the bottom, and finally lay another layer of titanium particles flat to form a sandwich-like mixed particle layer of titanium particle-titanium particle and stainless steel particle-titanium particle. Using selective laser melting (SLM) technology, put the mixed particles into the laser chamber, adjust the laser power to 500 W and the scanning speed to 2000 mm / s, and perform melting and recombination on the mixed particle layer to generate a composite plate body composed of a titanium layer, a titanium-stainless steel composite layer, and a titanium layer. When the plate body cools down, process the plate body until its thickness reaches 2 mm.

[0155] The test results show that the contact resistance of the water electrolysis bipolar plate prepared in this example is 0.61 mΩ·cm 2 , and the corrosion current density is 3.14 μA / cm 2 , having good performance output and durability.

[0156] Table 4 Test Results

[0157] Serial number <![CDATA[Contact resistance mΩ·cm 2 > <![CDATA[Corrosion current density μA / cm 2 > Example 10 0.67 3.15 Example 11 0.63 3.21 Example 12 0.61 3.14

[0158] Example 13

[0159] A continuous production line applicable to Examples 1-12. The production line consists of an annular guide rail and a driving electrical system to form a conveying line. A plurality of sliders driven by electricity are arranged on the annular guide rail to simultaneously place multiple stainless steel plates for batch conveying. Along the conveying direction of the annular guide rail, a plasma spraying area, a first thickness detection area, a die printing area, and a second thickness detection area for acting on the stainless steel plates are successively arranged on the production line. At the same time, the entire continuous production line is intelligently and logically controlled by a CPU control system. The plasma spraying area mainly includes a plasma spraying machine, the die printing area is mainly a screen printing machine, and the first thickness detection area and the second thickness detection area mainly include thickness detectors. The plasma spraying machine, the screen printing machine, and the thickness detector are all electrically connected to the CPU control system to achieve controllability of whether multiple areas work and their working sequences. Place multiple stainless steel plates on the above-mentioned sliders in sequence for conveying, and successively pass through plasma spraying, first thickness detection, screen printing, and second thickness detection for preparation. During this process, according to the actual size requirements of the metal bipolar plates and the thickness detection results, relevant data are recorded and real-time adjusted in the CPU system. If the size does not meet the requirements, it can be circularly conveyed to the corresponding area for re-brushing. Finally, the qualified ones are taken off by a robotic arm and conveyed to other production lines with a dryer.

[0160] This specific embodiment is only an explanation of the present invention and does not limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A PEM water electrolysis metal bipolar plate, characterized in that: the bipolar plate includes a substrate, and a microporous titanium layer and a functional coating are sequentially arranged on the surface of the substrate; the functional coating forms the flow field structure of the bipolar plate; the pore diameter of the microporous titanium layer is 100 nm - 10 μm; the microporous titanium layer contains spherical dehydrogenated titanium powder; the functional coating contains spherical atomized titanium powder; The preparation method of the PEM water electrolysis metal bipolar plate described above includes the following steps: (1) Spraying spherical dehydrogenated titanium powder onto the surface of the pretreated substrate by plasma spraying to form a microporous titanium layer; (2) Preparing a functional mixed slurry, and printing the functional mixed slurry onto the microporous titanium layer by die printing to form a flow field structure including the bipolar plate; the flow field structure includes flow channel grooves and other areas in the turbulence area except for the turbulence columns; (3) Drying and demolding to obtain a water electrolysis metal bipolar plate.

2. The PEM water electrolysis metal bipolar plate according to claim 1, characterized in that: a hydrophobic layer is provided in the flow channel grooves of the bipolar plate; a hydrophobic layer is provided in other areas of the turbulence area of the bipolar plate except for the turbulence columns.

3. The PEM water electrolysis metal bipolar plate according to claim 1, characterized in that: the substrate is one of a stainless steel plate body, a titanium-high alloy steel composite plate body, and a metal composite plate body; the metal composite plate body includes two pure titanium layers and one titanium-stainless steel composite layer, and the titanium-stainless steel composite layer is placed between the two pure titanium layers.

4. The PEM water electrolysis metal bipolar plate according to claim 3, characterized in that: the titanium-high alloy steel composite plate body is composed of titanium particles and high alloy steel particles, the particle sizes of the titanium particles and the high alloy steel particles are the same, and are between 60 - 80 μm; the weight of the titanium particles accounts for 10 - 15% of the total weight of the titanium-high alloy steel composite plate body; the high alloy steel contains one or more of the alloy elements Ni, Ti, and Mo, and the total alloy element mass content is 10% - 30%; the titanium-stainless steel composite layer is composed of titanium particles and stainless steel particles, the particle sizes of the titanium particles and the stainless steel particles are the same, and are between 60 - 80 μm, and the titanium particles account for 10 - 15% of the total weight of the mixed particles in the titanium-stainless steel composite layer; the particle sizes of the titanium particles in the pure titanium layer are the same as those of the titanium particles in the titanium-stainless steel composite layer, and the two pure titanium layers respectively account for 10 - 15% of the total weight of the composite plate body.

5. The PEM water electrolysis metal bipolar plate according to claim 1, characterized in that: the particle size of the spherical atomized titanium powder is 20 - 50 μm, and the particle size of the spherical dehydrogenated titanium powder is 30 - 100 μm.

6. The PEM water electrolysis metal bipolar plate according to claim 1, characterized in that: after the drying and demolding in step (3), a hydrophobic layer is printed in the flow channel grooves of the bipolar plate and other areas in the turbulence area except for the turbulence columns by die printing, and then dried and demolded.

7. The PEM water electrolysis metal bipolar plate according to claim 1, characterized in that: The conditions for the plasma spraying are as follows: the plasma enthalpy is 22 - 50 MJ / kg; the spraying speed is 600 - 1000 mm / s; the spraying temperature is 150 - 200 °C; The pretreatment method for the substrate is as follows: the substrate is polished step by step, and then polished and rinsed with clean water.

8. A PEM water electrolysis metal bipolar plate according to claim 1, characterized in that: The functional hybrid slurry includes: spherical atomized titanium powder with a particle size of 20 - 50 μm, a solvent, a binder, and a plasticizer; The solvent includes at least one of ethanol, toluene, or methanol; the binder includes one or a mixture of two of polyvinyl butyral resin or acrylic resin; the plasticizer includes one or a mixture of two or more of dioctyl phthalate, dibutyl phthalate, or propylene glycol polyester oxalate; the mass ratio between the spherical atomized titanium powder with a particle size of 50 - 100 μm, the solvent, the binder, and the plasticizer is 60 - 80:15 - 35:3 - 4:1 - 2.

9. A PEM water electrolysis metal bipolar plate according to claim 6, characterized in that: The slurry of the hydrophobic layer includes: fluorinated acetylene black, nano - antimony oxide, and a solvent; the solvent includes at least one of ethanol, toluene, or methanol; the mass ratio of fluorinated acetylene black, nano - antimony oxide, and the solvent is 30 - 40:10 - 20:40 - 60; wherein, the particle size of nano - antimony oxide is 5 - 50 nm; in the fluorinated acetylene black, the element proportion of fluorine element is 60 - 80 wt%.

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