A bipolar plate for PEM water electrolysis hydrogen production and preparation method thereof

Abstract

The present invention discloses a bipolar plate for PEM water electrolysis hydrogen production and a preparation method thereof, belonging to the field of water electrolysis hydrogen production. The flow field structure is a combination of two shapes: a trapezoidal shape and a rectangular shape. Half of the flow field structure near the cathode or anode inlet is rectangular, and half of the flow field structure near the cathode or anode outlet is trapezoidal. The connection between the two flow fields is an array point-shaped multifunctional area, and the composite flow field structure is a two-layer structure of a macroporous titanium layer and a microporous titanium layer; the present invention also discloses a composite flow field preparation method for a multi-shape integrated water electrolysis metal bipolar plate, which uses a mold printing method to print different titanium slurries on an alloy steel plate to prepare a composite structure of a water electrolysis bipolar plate flow field.

Description

Technical Field

[0001] The invention belongs to the field of water electrolysis hydrogen production, and specifically relates to a bipolar plate for PEM water electrolysis hydrogen production and a preparation method thereof. Background Art

[0002] As a clean energy source, hydrogen is becoming more and more popular. PEM water electrolysis technology can use the excess energy generated by wind and light energy to obtain hydrogen. 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 gas is high in purity, safe, efficient, and environmentally friendly, which can realize on-site hydrogen production and solve the problem of hydrogen transportation. Therefore, proton exchange membrane water electrolysis technology has important applications in the fields of energy, transportation, and chemical industry.

[0003] During the water electrolysis reaction, the anode loses electrons to generate oxygen, and the cathode gains electrons to generate hydrogen. The bipolar plate is one of the key technologies of proton exchange membrane water electrolysis technology. It has the functions of support, gas isolation, conduction and heat dissipation in the hydropower digester. Therefore, there are high requirements for the mechanical properties, electrical conductivity, thermal conductivity, chemical stability and cost of the bipolar plate material. The traditional water electrolysis bipolar plate contains a hydrogen frame, an oxygen frame and a separator. When making it, it is necessary to perform multiple complex processes such as positioning, gluing, hot pressing and welding. For example, patent CN104716329B first processes each component of the bipolar plate separately; then the separator is subjected to conductive treatment; finally, it is fixed and formed and welded into a complete bipolar plate. Due to the particularity of the water electrolysis operating environment, the water electrolysis bipolar plate material is generally made of pure titanium or other highly corrosion-resistant and conductive materials, which greatly increases its preparation cost. High-alloy steel plates are cheap, but due to the nature of the material itself, it is difficult to achieve the environment of water electrolysis operation without treatment. Therefore, high-alloy steel plates need to be processed additionally to meet their corrosion resistance requirements. As water electrolysis runs, water and gas coexist in the flow field. Regardless of the anode or cathode, the reaction begins at the anode inlet or cathode inlet of water electrolysis, and the hydrogen and oxygen generated by water electrolysis will be discharged from the electrolytic cell with the flow of the liquid. How to achieve rapid gas discharge without affecting the occurrence of subsequent reactions is the key to improving water electrolysis performance. Summary of the invention

[0004] The object of the present invention is to provide a bipolar plate for PEM water electrolysis hydrogen production and a preparation method thereof.

[0005] The above technical purpose of the present invention is achieved through the following technical solutions:

[0006] A bipolar plate for PEM water electrolysis hydrogen production, with an alloy steel plate as a substrate, wherein a microporous titanium layer a, a macroporous titanium layer and a microporous titanium layer b are sequentially provided on the surface of the substrate;

[0007] The pore sizes of the microporous titanium layer a and the microporous titanium layer b are both 100 nm-10 μm, and the pore size of the macroporous titanium layer is >10 μm and ≤100 μm;

[0008] The microporous titanium layer a contains at least spherical dehydrogenated titanium powder, the macroporous titanium layer contains at least spherical atomized titanium powder with a particle size of 50-100 μm and a pore-forming agent, and the microporous titanium layer b contains at least spherical atomized titanium powder with a particle size of 20-50 μm;

[0009] The macroporous titanium layer and the microporous titanium layer b form a composite flow field structure of the bipolar plate, and the composite flow field structure includes a trapezoidal flow channel ridge, a functional area and a rectangular flow channel ridge, the rectangular flow channel ridge is located near the cathode inlet or the anode inlet, and connects the material inlet with one side of the functional area, the trapezoidal flow channel ridge is located near the cathode outlet or the anode outlet, and connects the material outlet with the other side of the functional area, and the functional area is an array column. The present invention is further configured as follows: the height of the trapezoidal flow channel ridge and the rectangular flow channel ridge are both 0.3-1mm, the bottom width of the trapezoidal flow channel is 0.2-0.5mm, the opening width of the trapezoidal flow channel is 0.4-1mm, and the groove width of the rectangular flow channel is 0.5-1mm.

[0010] The present invention is further configured as follows: the thickness of the microporous titanium layer a is 0.1-0.4 mm; the thickness of the macroporous titanium layer and the microporous titanium layer b are both 0.3-0.5 mm.

[0011] The present invention is further configured as follows: the particle size of the spherical dehydrogenated titanium powder is 30-100 μm; the macroporous titanium layer contains spherical atomized titanium powder with a particle size of 50-100 μm, a solvent, a binder, a pore-forming agent and a plasticizer; the microporous titanium layer b contains spherical atomized titanium powder with a particle size of 20-50 μm, a solvent, a binder and a plasticizer.

[0012] The present invention is further configured as follows: the solvent in the macroporous titanium layer and the microporous titanium layer b is independently at least one of ethanol, toluene or methanol, the binder in the macroporous titanium layer and the microporous titanium layer b is independently at least one of polyvinyl butyral resin or acrylic resin, the plasticizer in the macroporous titanium layer and the microporous titanium layer b is independently at least one of dioctyl phthalate, dibutyl phthalate or propylene glycol oxalate polyester, and the pore-forming agent includes one or a combination of more than two of urea, ammonium bicarbonate, sodium carbonate and oxalic acid.

[0013] The present invention is further configured as follows: in the macroporous titanium layer, the mass ratio of spherical atomized titanium powder, solvent, binder, pore former and plasticizer is 20-40:52-64:2-10:3-4:1-2; in the microporous titanium layer b, the mass ratio of spherical atomized titanium powder, solvent, binder and plasticizer is 60-80:15-35:3-4:1-2.

[0014] The present invention is further configured as follows: the thickness of the alloy steel plate is 0.5-1 mm, the alloy steel plate contains one or more alloy elements of Ni, Ti, and Mo, and the total alloy element mass content is 10wt.%-30wt.%.

[0015] The present invention also provides a method for preparing a bipolar plate for PEM water electrolysis hydrogen production, comprising the following steps:

[0016] (1) Preparation of macroporous titanium layer slurry: Spherical atomized titanium powder with a particle size of 50-100 μm is stirred and mixed with a solvent, a binder, a pore former and a plasticizer to obtain a macroporous titanium layer slurry;

[0017] Preparation of microporous titanium layer b slurry: Spherical atomized titanium powder with a particle size of 20-50 μm is stirred and mixed with a solvent, a binder and a plasticizer to obtain a microporous titanium layer b slurry;

[0018] (2) Pretreatment of alloy steel plates;

[0019] (3) using plasma spraying to spray spherical dehydrogenated titanium powder onto the surface of the pretreated alloy steel plate to form a microporous titanium layer a;

[0020] (4) printing the macroporous titanium layer slurry onto the microporous titanium layer a by mold printing, and drying and demolding;

[0021] (5) transferring the plate to a vacuum furnace and performing programmed temperature sintering to prepare a metal electrode plate having a macroporous titanium layer;

[0022] (6) The microporous titanium layer b slurry is printed onto the macroporous titanium layer by mold printing, and then dried and demolded to form a microporous titanium layer b on the surface of the macroporous titanium layer, thereby preparing a water electrolysis bipolar plate.

[0023] The present invention is further configured as follows: the conditions for the plasma spraying are: plasma enthalpy is 22-50 MJ / kg; spraying speed is 600-1000 mm / s; and spraying temperature is 150-200°C.

[0024] The present invention is further configured as follows: the programmed temperature rising conditions are: argon protection flow rate: 10-100 mL / min, vacuum degree: -0.1 MPa to -0.9 MPa, time: 30-100 min; heating rate: 5-20° C. / min; calcination temperature: 600-1300° C.

[0025] The present invention is further configured as follows: the drying temperature is 100-150° C. and the drying time is 3-5 minutes.

[0026] The present invention is further configured as follows: the pretreatment of the alloy steel plate includes: grinding, polishing and cleaning the surface of the alloy steel plate, then ultrasonically cleaning it in an acetone solution, taking it out and ultrasonically cleaning it with ultrapure water, cleaning it, taking it out and blowing it dry for use.

[0027] The present invention is further configured as follows: the grinding is performed step by step using sandpaper with a mesh number of 500 to 1200.

[0028] The present invention is further configured as follows: the grinding is performed step by step using sandpaper with mesh numbers of 500, 700, 900 and 1200 respectively.

[0029] The present invention is further configured as follows: steps (3)-(4) are completed using a continuous production line with an annular guide rail, the annular guide rail is provided with a plurality of electrically driven sliders, and the stainless steel plates are placed on the sliders; the continuous production line is provided with a plasma spraying area, a No. 1 thickness detection area, a mold printing area, and a No. 2 thickness detection area in sequence, and the annular guide rail and the continuous production line are both connected to the control system circuit.

[0030] The present invention has the following beneficial effects:

[0031] 1. High performance: The present invention adopts a composite flow field structure. The flow field shape near the anode and cathode entrances is rectangular, and the flow field shape near the anode and cathode exits is trapezoidal. Since the electrochemical reaction starts at the entrance and hydrogen and oxygen are generated, there is less gas in the flow field at this time. The use of rectangular flow channels can achieve a good gas transmission effect. The closer to the anode and cathode exits, the more gas will accumulate in the flow field. Therefore, the present invention sets the flow field shape near the anode and cathode exits to a trapezoidal shape, increases the opening area of ​​the flow field, increases the contact area between the bipolar plate flow field opening and the membrane electrode, ensures the reaction and improves the timely removal of the generated hydrogen and oxygen, improves the mass transfer balance between the reaction water, generated gas, and excess water in the flow field, thereby improving the overall water electrolysis performance. The present invention sets a functional area with a gas bypass function between the rectangular flow channel and the trapezoidal flow channel, which can better disperse a large amount of gas in the rectangular flow channel more evenly into the trapezoidal flow channel.

[0032] 2. Strong interlayer bonding force: Before printing the flow field structure, the present invention first performs plasma spraying on the high-alloy steel plate, that is, a microporous titanium layer is sprayed on the surface of the high-alloy steel plate by plasma spraying, which is beneficial for small-particle titanium particles to penetrate into the steel surface, distribute more densely and more evenly, effectively reduce contact resistance, and increase the bonding force between the high-alloy steel plate and the titanium layer. Then, a macroporous titanium layer and a microporous titanium layer b are prepared by printing. At this time, combined with the influence of printing pressure, the mutual penetration of titanium particles between the layers can be effectively enhanced, thereby improving the bonding force between the titanium layer and the high-alloy steel plate.

[0033] 3. Strong transmission capacity: The present invention sets up a composite layer structure of the flow field. First, a microporous titanium layer a is prepared on the surface of a high-alloy steel plate by plasma spraying, and then a flow field structure is prepared on the microporous titanium layer a by mold printing, and then it is vacuum sintered to form a macroporous and porous flow field structure. Finally, a high-concentration microporous titanium layer b slurry is printed again on the macroporous and porous flow field. The high-concentration microporous titanium slurry reduces the infiltration into the macropores, and finally forms a composite flow field structure. At the bottom of the groove of the flow field, it is a macroporous and porous structure, which increases the flow of liquid and gas and improves its mass transfer capacity. On the back of the flow field, it is a relatively fine titanium layer structure, which increases its electrical conductivity with the membrane electrode and reduces its contact resistance. In addition, the present invention also adds an array columnar multifunctional area at the junction of the two flow field structures, so that the flow path of the liquid in the flow field is diversified, which is beneficial to the conversion, distribution and conduction of the liquid in the two flow fields of different shapes, combined with the mutual superposition of titanium layers with different pore sizes, to improve the output performance of the overall water electrolysis bipolar plate.

[0034] 4. Low preparation cost: Compared with the traditional pure titanium plate for preparing water electrolysis bipolar plates, the present invention prepares a titanium layer on a metal high-alloy steel plate substrate to form a flow field and a multifunctional area in an integrated manner, which greatly reduces the preparation cost. The present invention can prepare water electrolysis bipolar plates in an integrated manner. In the traditional preparation process, the separator and the hydrogen and oxygen frame need to be machined separately, and then glued together to realize the assembly of the bipolar plate. In this way, due to the presence of glue, the bonding strength and integrity will affect the resistance and air tightness of the bipolar plate.

[0035] 5. The present invention adopts a continuous production line with a circular guide rail, and through the intelligent measurement and control of the thickness detection equipment and the control system, the cyclic transmission of batches of stainless steel plates on this production line can be realized to achieve continuous preparation; and this application is based on the design of the circular guide rail. Before the oven drying process, it is not necessary to expand the length of the transmission track, so as to fully realize the natural cooling of the stainless steel plate after plasma spraying and the natural air drying after mold printing, so as to achieve continuous preparation in subsequent multiple spraying and printing processes; in addition, the cyclic transmission of stainless steel plates can be realized without increasing the number of equipment, which saves costs and effectively avoids the problem of inconsistent debugging of multiple equipment affecting the product qualification rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] 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.

[0037] Figure 1Schematic diagram of the mold.

[0038] Figure 2 It is the trapezoidal section of the mold.

[0039] Figure 3 It is the cross section of the rectangular part of the mold.

[0040] Figure 4 It is the trapezoidal flow field cross section of the bipolar plate.

[0041] Figure 5 It is the rectangular flow field cross section of the bipolar plate.

[0042] In the figure: 1. trapezoidal flow field mold opening; 2. functional area flow field mold opening; 3. rectangular flow field mold opening; 1-1. trapezoidal flow field injection port; 3-1. rectangular flow field injection port; 4. trapezoidal flow channel groove; 4-1. trapezoidal flow channel opening; 4-2. trapezoidal flow channel spine; 2-1. functional area; 5. rectangular flow channel groove; 6. rectangular flow channel spine. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0044] Example 1

[0045] Preparation of macroporous titanium layer slurry: Weigh 20g of spherical atomized titanium powder with a particle size of 50μm (the spherical atomized titanium powder obtained by atomization treatment can be prepared by a general method in the art), 64g of anhydrous ethanol, 10g of polyvinyl butyral resin, 4g of ammonium bicarbonate, and 2g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for later use.

[0046] Preparation of microporous titanium layer b slurry: weigh 60g of spherical atomized titanium powder with a particle size of 20μm, 35g of anhydrous ethanol, 4g of polyvinyl butyral resin, and 1g of dioctyl phthalate in a beaker, and stir them evenly with a mechanical stirrer for later use.

[0047] A piece of high-alloy steel with a Mo alloy mass content of 30% was cut with a thickness of 0.5 mm and an area of ​​20 cm x 10 cm, and polished step by step using 200-500 mesh sandpaper. The high-alloy steel plate was then ultrasonically cleaned in an acetone solution for 3 times, each time for 10 minutes. After cleaning, it was rinsed with ultrapure water and then taken out and blown dry.

[0048] The cleaned high alloy steel plate is placed on the plasma spraying platform, and the spraying machine conditions are set to plasma enthalpy of 22MJ / kg; spraying speed of 600mm / s; spraying temperature of 150°C, and spherical dehydrogenated titanium powder with a particle size of 30μm (spherical dehydrogenated titanium powder obtained by dehydrogenation treatment can be prepared by a general method in the field) is sprayed on the surface of the high alloy steel to form a microporous titanium layer a with a thickness of 0.1mm, and the pore size of the microporous titanium layer a is 10μm. Subsequently, the mold is placed on the surface of the high alloy steel, and the macroporous titanium layer slurry is printed on the surface of the microporous titanium layer a according to the shape of the mold, with a thickness of 0.3mm, and then placed in a 100°C oven for heat treatment for 5min. After the time is up, the mold is removed and placed in a -0.1MPa vacuum furnace at a temperature of 1300°C for 30min, with an argon protection flow rate of 10mL / min. After the time is up, it is taken out to obtain a metal plate with a macroporous titanium layer with a pore size of 100μm. Then, the mold was placed on the surface of the macroporous titanium layer, and the microporous titanium layer b slurry was printed on the surface of the macroporous titanium layer along the shape of the mold, with a thickness of 0.3 mm, and then dried again at a temperature of 100°C for 5 min. Finally, the mold was taken out, and a microporous titanium layer b with a pore size of 10 μm was further formed on the surface of the macroporous titanium layer, obtaining a water electrolysis electrode with multiple shapes (such as Figure 2-5 shown).

[0049] The structure of the mold is as follows Figure 1 As shown, the mold includes a trapezoidal flow field mold opening 1, a functional area flow field mold opening 2, and a rectangular flow field mold opening 3. The trapezoidal flow field mold opening 1 is a plurality of parallel arranged trapezoidal groove structures. Through mold printing, the flow field structure of the bipolar plate presents a trapezoidal flow channel structure, forming a trapezoidal flow channel ridge 4-2 and a corresponding trapezoidal flow field groove 4, and the trapezoidal bottom edge of the trapezoidal flow channel structure is close to the high alloy steel plate, forming the bottom of the trapezoidal flow channel groove, and the trapezoidal top edge is away from the high alloy steel plate, forming a trapezoidal flow field opening 4-1 of the trapezoidal flow channel groove. The rectangular flow field mold opening 3 is a plurality of parallel arranged rectangular groove structures. Through mold printing, the flow field structure of the bipolar plate presents a rectangular flow channel structure, forming a rectangular flow field groove 5 and a rectangular flow channel ridge 6. The functional area flow field mold opening 2 is located between the trapezoidal flow field mold opening 1 and the rectangular flow field mold opening 3, and is a plurality of regularly alternately arranged hollow structures. Through mold printing, an array cylindrical functional area 2-1 (for gas turbulence) is formed between the rectangular flow channel and the trapezoidal flow channel of the bipolar plate. The groove structure of the rectangular flow channel is parallel to the groove structure of the trapezoidal flow channel and corresponds in position. The corresponding rectangular flow channel groove is connected in position with the trapezoidal flow channel groove and corresponds to the material inlet and outlet.

[0050] The trapezoidal flow field mold opening 1 of the mold is provided with a trapezoidal flow field injection port 1-1, and the rectangular flow field mold opening 3 is provided with a rectangular flow field injection port 3-1. The mold is placed on the plate, and the slurry is injected through the trapezoidal flow field injection port or the rectangular flow field injection port. After treatment, the flow field structure can be formed. When preparing the microporous titanium layer b with a trapezoidal flow field structure, the size of the trapezoidal flow field mold side of the mold is adjusted accordingly, so that the side of the obtained bipolar plate with the trapezoidal flow field structure is guaranteed to be an overall trapezoid.

[0051] After testing, the contact resistance of the prepared plate is 0.5mΩ·cm 2 , the corrosion current density is 2.5μA / cm 2 , as shown in Table 1, it has excellent output performance.

[0052] Example 2

[0053] Preparation of macroporous titanium layer slurry: weigh 30g of spherical atomized titanium powder with a particle size of 75μm, 58g of anhydrous ethanol, 6g of polyvinyl butyral resin, 3.5g of ammonium bicarbonate, and 1.5g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for later use.

[0054] Preparation of microporous titanium layer b slurry: weigh 70g of spherical atomized titanium powder with a particle size of 35μm, 20g of anhydrous ethanol, 3.5g of polyvinyl butyral resin, and 1.5g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for later use.

[0055] A piece of high-alloy steel with a Ti alloy mass content of 10% was cut with a thickness of 0.5 mm and an area of ​​20 cm x 10 cm, and polished step by step using 200-500 mesh sandpaper. The high-alloy steel plate was then ultrasonically cleaned in an acetone solution for 3 times, each time for 10 minutes. After cleaning, it was rinsed with ultrapure water and then taken out and blown dry.

[0056] The cleaned high alloy steel plate is placed on the plasma spraying platform, and the spraying machine conditions are set to plasma enthalpy of 36MJ / kg; spraying speed of 800mm / s; spraying temperature of 175℃, and spherical dehydrogenated titanium powder with a particle size of 60μm is sprayed on the surface of the high alloy steel to form a microporous titanium layer a with a thickness of 0.4mm, and the pore size of the microporous titanium layer a is 100nm. Then the mold is placed on the surface of the high alloy steel, and the macroporous titanium layer slurry is printed on the surface of the microporous titanium layer a according to the shape of the mold, with a thickness of 0.4mm, and then placed in a 125℃ oven for heat treatment for 4min. After the time is up, the mold is removed and placed in a -0.5MPa vacuum furnace at a temperature of 950℃, a time of 60min, and an argon protection flow rate of 50mL / min. After the time is up, it is taken out to obtain a metal substrate with a macroporous titanium layer with a pore size of 12μm. Then, the mold is placed on the surface of the macroporous titanium layer, and the microporous titanium layer b slurry is printed on the surface of the macroporous titanium layer along the shape of the mold, with a thickness of 0.4 mm, and then dried again at a temperature of 125° C. for 4 minutes, and finally the mold is taken out, and a microporous titanium layer b with a pore size of 100 nm is further formed on the surface of the macroporous titanium layer, and a water electrolysis electrode plate with multiple shapes is obtained. The mold structure is the same as that of Example 1.

[0057] The prepared water electrolysis plate has a multi-layer structure and a titanium layer is printed on high-alloy steel. After testing, the contact resistance of the prepared plate is only 0.53mΩ·cm 2 , the corrosion current density is 2.57μA / cm 2 Therefore, the prepared plates have excellent output and performance in terms of both performance and durability.

[0058] Example 3

[0059] Preparation of macroporous titanium layer slurry: weigh 40g of spherical atomized titanium powder with a particle size of 100μm, 52g of anhydrous ethanol, 2g of polyvinyl butyral resin, 3g of ammonium bicarbonate, and 1g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for later use.

[0060] Preparation of microporous titanium layer b slurry: weigh 80g of spherical atomized titanium powder with a particle size of 50μm, 15g of anhydrous ethanol, 3g of polyvinyl butyral resin, and 1g of dioctyl phthalate in a beaker, and stir them evenly with a mechanical stirrer for later use.

[0061] A piece of high-alloy steel with a Ni alloy mass content of 30% was cut with a thickness of 0.5 mm and an area of ​​20 cm x 10 cm, and polished step by step using 200-500 mesh sandpaper. The high-alloy steel plate was then ultrasonically cleaned in an acetone solution for 3 times, each time for 10 minutes. After cleaning, it was rinsed with ultrapure water and then taken out and blown dry.

[0062] The cleaned high alloy steel plate is placed on the plasma spraying platform, and the spraying machine conditions are set to plasma enthalpy of 50MJ / kg; spraying speed of 1000mm / s; spraying temperature of 200℃, and spherical dehydrogenated titanium powder with a particle size of 100μm is sprayed on the surface of the high alloy steel to form a microporous titanium layer a with a thickness of 0.4mm, and the pore size of the microporous titanium layer a is 10μm. Subsequently, the mold is placed on the surface of the high alloy steel, and the macroporous titanium layer slurry is printed on the surface of the microporous titanium layer a according to the shape of the mold, with a thickness of 0.5mm, and then placed in a 150℃ oven for heat treatment for 3min. After the time is up, the mold is removed and placed in a -0.9MPa vacuum furnace at a temperature of 600℃, a time of 100min, and an argon protection flow rate of 100mL / min. After the time is up, it is taken out to obtain a metal substrate with a macroporous titanium layer with a pore size of 50μm. Then, the mold is placed on the surface of the macroporous titanium layer, and the microporous titanium layer b slurry is printed on the surface of the macroporous titanium layer along the shape of the mold, with a thickness of 0.5 mm, and dried again at a temperature of 150° C. for 3 minutes, and finally the mold is taken out, and a microporous titanium layer b with a pore size of 10 μm is further formed on the surface of the macroporous titanium layer, and a water electrolysis electrode plate with multiple shapes is obtained. The mold structure is the same as that of Example 1.

[0063] The prepared water electrolysis plate has a multi-layer structure and a titanium layer is printed on high-alloy steel. After testing, the contact resistance of the prepared plate is only 0.57mΩ·cm 2 , the corrosion current density is 2.59μA / cm 2 Therefore, the prepared plates have excellent output and performance in terms of both performance and durability.

[0064] Example 4

[0065] A continuous production line applicable to embodiments 1-3, the production line consists of a circular guide rail and a driving electrical transmission line, a plurality of electrically driven sliders are arranged on the circular guide rail, so as to simultaneously place a plurality of stainless steel plates to realize batch transmission, and at the same time, along the transmission direction of the circular guide rail, a plasma spraying area, a No. 1 thickness detection area, a mold printing area, a No. 2 thickness detection area, and a drying area are sequentially arranged on the production line for acting on the stainless steel plates, and 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 sprayer, the mold printing area mainly includes a screen printer, the No. 1 thickness detection area and the No. 2 thickness detection area mainly include thickness detectors, etc. The ion sprayer, screen printer, and thickness detector are all connected to the CPU control system circuit to achieve controllability of whether multiple areas are working and the working order; multiple stainless steel plates are placed on the above-mentioned slider in turn for transmission, and are prepared in turn through plasma spraying, the first thickness detection, screen printing, and the second thickness detection. In this process, according to the actual size requirements of the metal bipolar plate and the thickness detection results, the relevant data are recorded and controlled in real time in the CPU system. If the size is not met, it can be circulated and transmitted to the corresponding area for re-brushing. At the same time, there are manual positions and robotic arm positions in the entire production line. Finally, those that meet the requirements are taken down by the robotic arm and transmitted to other production lines.

[0066] Comparative Example 1

[0067] Preparation of macroporous titanium layer slurry: weigh 20g of spherical atomized titanium powder with a particle size of 50μm, 64g of anhydrous ethanol, 10g of polyvinyl butyral resin, 4g of ammonium bicarbonate, and 2g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for later use.

[0068] Preparation of microporous titanium layer b slurry: weigh 60g of spherical atomized titanium powder with a particle size of 20μm, 35g of anhydrous ethanol, 4g of polyvinyl butyral resin, and 1g of dioctyl phthalate in a beaker, and stir them evenly with a mechanical stirrer for later use.

[0069] A piece of high-alloy steel with a Mo alloy mass content of 30% was cut with a thickness of 0.5 mm and an area of ​​20 cm x 10 cm, and polished step by step using 200-500 mesh sandpaper. The high-alloy steel plate was then ultrasonically cleaned in an acetone solution for 3 times, each time for 10 minutes. After cleaning, it was rinsed with ultrapure water and then taken out and blown dry.

[0070] The mold is placed on the surface of high alloy steel, and the macroporous titanium layer slurry is printed on the surface of the high alloy steel plate according to the shape of the mold, with a thickness of 0.5mm, and then placed in a 100°C oven for heat treatment for 5min, and the mold is removed after the time is up, and placed in a -0.1MPa vacuum furnace at a temperature of 1300°C for 30min, with an argon protection flow rate of 10mL / min, and then the mold is placed on the surface again, and the microporous titanium layer b slurry is printed on the surface of the plate along the shape of the mold, and dried again at a temperature of 100°C for 5min, and finally the mold is taken out to obtain a water electrolysis plate with multiple shapes. The mold structure is the same as in Example 1.

[0071] Since there is no microporous titanium layer a plasma sprayed on the high alloy steel plate, there is no titanium layer covering the bottom of the groove, and its contact resistance is relatively high, reaching 3mΩ·cm 2 , the corrosion current density also reached 5μA / cm 2 ,From the data, it can be seen that the performance of the plates is relatively poor, both in terms of output performance and durability.

[0072] Comparative Example 2

[0073] Preparation of macroporous titanium layer slurry: weigh 20g of spherical atomized titanium powder with a particle size of 50μm, 64g of anhydrous ethanol, 10g of polyvinyl butyral resin, 4g of ammonium bicarbonate, and 2g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for later use.

[0074] Preparation of microporous titanium layer b slurry: weigh 60g of spherical atomized titanium powder with a particle size of 20μm, 35g of anhydrous ethanol, 4g of polyvinyl butyral resin, and 1g of dioctyl phthalate in a beaker, and stir them evenly with a mechanical stirrer for later use.

[0075] A piece of high-alloy steel with a Mo alloy mass content of 10% was cut with a thickness of 0.5 mm and an area of ​​20 cm x 10 cm, and polished step by step using 200-500 mesh sandpaper. The high-alloy steel plate was then ultrasonically cleaned in an acetone solution for 3 times, each time for 10 minutes. After cleaning, it was rinsed with ultrapure water and then taken out and blown dry.

[0076] The cleaned high alloy steel plate is placed on the plasma spraying platform, and the spraying machine conditions are set to plasma enthalpy of 22MJ / kg; spraying speed of 600mm / s; spraying temperature of 150℃, and spherical dehydrogenated titanium powder with a particle size of 30μm is sprayed on the surface of the high alloy steel to form a microporous titanium layer a, and the pore size of the microporous titanium layer a is 10μm. Then the mold is placed on the surface of the high alloy steel, and the macroporous titanium layer slurry is printed on the surface of the microporous titanium layer a according to the shape of the mold. The mold has no multi-shaped structure, no functional area at the joint, and only has a rectangular parallel flow field groove structure with a thickness of 0.5mm. Then it is placed in a 100℃ oven for heat treatment for 5min. After the time is up, it is taken out and removed from the mold, and placed in a -0.1MPa vacuum furnace at a temperature of 1300℃, a time of 30min, and an argon protection flow rate of 10mL / min. After the time is up, it is taken out to obtain a metal plate with a macroporous titanium layer with a pore size of 100μm. Subsequently, the above-mentioned mold is placed on the surface, and the microporous titanium layer b slurry is printed along the shape of the mold onto the surface of the macroporous titanium layer, and dried again at a temperature of 100°C for 5 minutes. Finally, the mold is removed, and a microporous titanium layer b with a pore size of 10 μm is further formed on the surface of the macroporous titanium layer to obtain a water electrolysis plate with a parallel flow field.

[0077] Compared with the embodiment of the present application, the comparative example 2 adopts the plasma spraying and titanium layer printing method, and the contact resistance of the plate is lower, which is 0.59 mΩ·cm. 2 , with good output performance; and the bipolar plate and membrane electrode were assembled into an electrolyzer, and the electrolyzer was tested at 1500mA cm -2 The voltage under the condition is 1.7V and the mass transfer resistance is 200mΩcm 2 However, Comparative Example 2 did not use a composite flow field structure, but a parallel flow field structure. The electrolyzer was assembled using the same membrane electrode and bipolar plate prepared in Comparative Example 2. The electrolyzer was tested under the same test conditions at 1500 mA cm -2 The voltage under the condition is 1.98V and the mass transfer resistance is 500mΩcm 2 It can be seen that the bipolar plate prepared by the present invention has a small mass transfer resistance, which effectively improves the transmission performance of the bipolar plate and the output performance of the electrolyzer. In addition, comparative example 2 does not adopt a composite flow field structure, but a parallel flow field structure with average durability. The corrosion current density is 3μA / cm 2 , which is 20% higher than Example 1.

[0078] Comparative Example 3

[0079] Preparation of macroporous titanium layer slurry: weigh 20g of spherical atomized titanium powder with a particle size of 50μm, 64g of anhydrous ethanol, 10g of polyvinyl butyral resin, 4g of ammonium bicarbonate, and 2g of dioctyl phthalate in a beaker, and stir evenly with a mechanical stirrer for later use.

[0080] A piece of high-alloy steel with a Mo alloy mass content of 30% was cut with a thickness of 0.5 mm and an area of ​​20 cm x 10 cm, and polished step by step using 200-500 mesh sandpaper. The high-alloy steel plate was then ultrasonically cleaned in an acetone solution for 3 times, each time for 10 minutes. After cleaning, it was rinsed with ultrapure water and then taken out and blown dry.

[0081] The cleaned high-alloy steel plate is placed on a plasma spraying platform, and the spraying machine conditions are set to a plasma enthalpy of 22 MJ / kg; a spraying speed of 600 mm / s; and a spraying temperature of 150°C. Spherical dehydrogenated titanium powder with a particle size of 30 μm is sprayed onto the surface of the high-alloy steel. Subsequently, the mold is placed on the surface of the high-alloy steel, and the slurry is printed onto the surface of the high-alloy steel plate according to the mold shape in Example 1, with a thickness of 0.5 mm. It is then placed in a 100°C oven for heat treatment for 5 minutes. After the time is up, the mold is removed to obtain a water electrolysis plate with multiple shapes.

[0082] Compared with the embodiment of the present application, in Comparative Example 3, only the macroporous titanium layer slurry is printed to form a functional coating. After testing, the prepared plate has excellent output performance based on the plasma spraying of high alloy steel plate and the mold printing of macroporous titanium layer, and the contact resistance is 0.53mΩ·cm 2 , but without a multi-layer structure, during operation, its internal water-gas transmission performance is not as good as that of Example 1, and its corrosion current density is relatively high, which is 2.78μA / cm 2 .

[0083] Table 1 Test results

[0084] Serial number <![CDATA[Contact resistance mΩ·cm 2 > <![CDATA[Corrosion current density μA / cm 2 > Example 1 0.5 2.5 Example 2 0.53 2.57 Example 3 0.57 2.59 Comparative Example 1 3 5 Comparative Example 2 0.59 3 Comparative Example 3 0.53 2.78

[0085] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, 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 bipolar plate for PEM water electrolysis hydrogen production, characterized in that: An alloy steel plate is used as a substrate, and a microporous titanium layer a, a macroporous titanium layer and a microporous titanium layer b are sequentially provided on the surface of the substrate; The pore sizes of the microporous titanium layer a and the microporous titanium layer b are both 100 nm-10 μm, and the pore size of the macroporous titanium layer is >10 μm and ≤100 μm; The microporous titanium layer a contains at least spherical dehydrogenated titanium powder, the macroporous titanium layer contains at least spherical atomized titanium powder with a particle size of 50-100 μm and a pore-forming agent, and the microporous titanium layer b contains at least spherical atomized titanium powder with a particle size of 20-50 μm; The macroporous titanium layer and the microporous titanium layer b form a composite flow field structure of the bipolar plate, and the composite flow field structure includes a trapezoidal flow channel ridge, a functional area and a rectangular flow channel ridge. The rectangular flow channel ridge is located near the cathode inlet or the anode inlet and connects the material inlet with one side of the functional area. The trapezoidal flow channel ridge is located near the cathode outlet or the anode outlet and connects the material outlet with the other side of the functional area. The functional area is an array column.

2. A bipolar plate for PEM water electrolysis hydrogen production according to claim 1, characterized in that: The heights of the ridges of the trapezoidal flow channel and the rectangular flow channel are both 0.3-1 mm, the groove bottom width of the trapezoidal flow channel is 0.2-0.5 mm, the opening width of the trapezoidal flow channel is 0.4-1 mm, and the groove width of the rectangular flow channel is 0.5-1 mm.

3. A bipolar plate for PEM water electrolysis hydrogen production according to claim 1, characterized in that: The thickness of the microporous titanium layer a is 0.1-0.4 mm; the thickness of the macroporous titanium layer and the microporous titanium layer b are both 0.3-0.5 mm.

4. A bipolar plate for PEM water electrolysis hydrogen production according to claim 1, characterized in that: The particle size of the spherical dehydrogenated titanium powder is 30-100 μm; the macroporous titanium layer contains spherical atomized titanium powder with a particle size of 50-100 μm, solvent, binder, pore former and plasticizer; the microporous titanium layer b contains spherical atomized titanium powder with a particle size of 20-50 μm, solvent, binder and plasticizer.

5. A bipolar plate for PEM water electrolysis hydrogen production according to claim 4, characterized in that: The solvent in the macroporous titanium layer b and the microporous titanium layer b is independently at least one of ethanol, toluene or methanol, the binder in the macroporous titanium layer b and the microporous titanium layer b is independently at least one of polyvinyl butyral resin or acrylic resin, the plasticizer in the macroporous titanium layer b and the microporous titanium layer b is independently at least one of dioctyl phthalate, dibutyl phthalate or propylene glycol oxalate polyester, and the pore-forming agent includes one or a combination of more than two of urea, ammonium bicarbonate, sodium carbonate and oxalic acid.

6. A bipolar plate for PEM water electrolysis hydrogen production according to claim 4, characterized in that: In the macroporous titanium layer, the mass ratio of spherical atomized titanium powder, solvent, binder, pore former and plasticizer is 20-40:52-64:2-10:3-4:1-2; in the microporous titanium layer b, the mass ratio of spherical atomized titanium powder, solvent, binder and plasticizer is 60-80:15-35:3-4:1-2.

7. A bipolar plate for PEM water electrolysis hydrogen production according to claim 1, characterized in that: The thickness of the alloy steel plate is 0.5-1 mm. The alloy steel plate contains one or more alloy elements of Ni, Ti and Mo, and the mass content of the total alloy elements is 10wt.%-30wt.%.

8. A method for preparing a bipolar plate for PEM water electrolysis hydrogen production according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Preparation of macroporous titanium layer slurry: Spherical atomized titanium powder with a particle size of 50-100 μm is stirred and mixed with a solvent, a binder, a pore former and a plasticizer to obtain a macroporous titanium layer slurry; Preparation of microporous titanium layer b slurry: Spherical atomized titanium powder with a particle size of 20-50 μm is stirred and mixed with a solvent, a binder and a plasticizer to obtain a microporous titanium layer b slurry; (2) Pretreatment of alloy steel plates; (3) using plasma spraying to spray spherical dehydrogenated titanium powder onto the surface of the pretreated alloy steel plate to form a microporous titanium layer a; (4) printing the macroporous titanium layer slurry onto the microporous titanium layer a by mold printing, and drying and demolding; (5) transferring the plate to a vacuum furnace and performing programmed temperature sintering to prepare a metal electrode plate having a macroporous titanium layer; (6) The microporous titanium layer b slurry is printed onto the macroporous titanium layer by mold printing, and then dried and demolded to form a microporous titanium layer b on the surface of the macroporous titanium layer, thereby preparing a water electrolysis bipolar plate.

9. The method for preparing a bipolar plate for PEM water electrolysis hydrogen production according to claim 8, characterized in that: The conditions of the plasma spraying are: plasma enthalpy is 22-50MJ / kg; spraying speed is 600-1000mm / s; spraying temperature is 150-200°C; The conditions for the programmed temperature rise in step (5) are: argon protection flow rate: 10-100 mL / min, vacuum degree: -0.1 MPa to -0.9 MPa, time: 30-100 min; heating rate: 5-20°C / min; The calcination temperature is 600-1300℃; The drying temperature is 100-150°C; The pretreatment of the alloy steel plate includes: grinding, polishing and cleaning the surface of the alloy steel plate, then ultrasonically cleaning it in an acetone solution, ultrasonically cleaning it with ultrapure water after taking it out, and then taking it out and blowing it dry for use.

10. The method for preparing a bipolar plate for PEM water electrolysis hydrogen production according to claim 8, characterized in that: Steps (3)-(4) are completed using a continuous production line with a circular guide rail, on which are provided several electrically driven sliders, on which are placed stainless steel plates; the continuous production line is provided with a plasma spraying area, a No. 1 thickness detection area, a mold printing area, and a No. 2 thickness detection area in sequence, and the circular guide rail and the continuous production line are both connected to the control system circuit.

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