PEM water electrolysis bipolar plate and its manufacturing method

Abstract

The present invention discloses a PEM water electrolysis bipolar plate and its manufacturing method, which is related to the field of hydrogen production by water electrolysis. The present invention uses a stainless steel plate as a substrate, which is provided with through-slit structures identical to and positioned corresponding to the flow path ridges. Titanium layers are formed on both the top and bottom surfaces of the substrate, filling the through-slit structures and connecting the top and bottom surfaces of the titanium layers. A layer of spherical dehydrogenated titanium powder and a functional coating layer are sequentially formed on the surface of the titanium layer. The functional coating layer forms the flow path ridges, turbulent columns, and hydrogen-oxygen flames of the bipolar plate. The pore size of the spherical dehydrogenated titanium powder layer is 100 nm to 10 μm, and the titanium layer, spherical dehydrogenated titanium powder layer, and functional coating layer all contain titanium powder. The present invention improves the electrical conductivity of the bipolar plate while using low-cost stainless steel plate, thereby improving the overall performance of the bipolar plate for water electrolysis.

Description

[Technical Field]

[0001] The present invention relates to a PEM water electrolysis bipolar plate and a manufacturing method thereof, and belongs to the field of hydrogen production by water electrolysis. [Background technology]

[0002] Bipolar plates are a core component of water electrolyzers and account for a large portion of the weight and cost of the battery pack. Specifically, bipolar plates are equipped with flow ridges, turbulent flow areas including turbulent columns, hydrogen and oxygen frames, bridge areas, as well as flow grooves and hydrogen and oxygen chambers. The flow field structure of the bipolar plate is formed by the flow ridges, flow grooves, turbulent flow areas, hydrogen and oxygen frames, and bridge areas. Bipolar plates are required to have excellent electrical conductivity, heat transfer, and corrosion resistance, as well as high mechanical strength and gas impermeability, making them a key development focus and challenge. Bipolar plates for solid polymer electrolyte water electrolyzers are typically made of metal, which offers not only toughness but also excellent machinability, electrical conductivity, heat transfer, and density.

[0003] The application of bipolar plates in water electrolysis requires, for example, operation in high-pressure environments and fluctuating conditions, which are much harsher than those of fuel cells. Conventional stainless steel plates are therefore difficult to meet these operating conditions and prone to corrosion. Furthermore, stainless steel plates have low electrical conductivity, resulting in significant energy loss during operation. Therefore, titanium and other materials with excellent corrosion resistance and electrical conductivity are typically used for water electrolysis. However, using pure titanium to manufacture bipolar plates significantly increases the operating costs of water electrolysis. Therefore, developing technology to improve corrosion resistance and electrical conductivity while utilizing low-cost stainless steel materials is an extremely important challenge. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made in view of the problems in the prior art, and an object of the present invention is to provide a low-cost, high-performance PEM water electrolysis bipolar plate and a mass-production method thereof. [Means for solving the problem]

[0005] The above technical object of the present invention is achieved by the following technical means.

[0006] The present invention provides a PEM water electrolysis bipolar plate, which uses a stainless steel plate as a substrate, and the substrate is provided with through-slit structures that correspond to the positions of flow path ridges and are parallel to each other. A mixed titanium layer is provided on both the upper and lower surfaces of the substrate, and the mixed titanium layer fills the through-slit structures to connect the upper and lower surfaces of the mixed titanium layer. A spherical dehydrogenated titanium powder layer and a functional coating layer are sequentially provided on the surface of the mixed titanium layer, and the functional coating layer forms a flow field structure of the bipolar plate, and both the mixed titanium layer and the functional coating layer contain spherical atomized titanium powder.

[0007] Furthermore, the particle size of the spherical atomized titanium powder is 20 to 50 μm, and the particle size of the spherical dehydrogenated titanium powder is 30 to 100 μm. Micropores are distributed in the spherical dehydrogenated titanium powder layer, and the pore size of the micropores is 100 nm to 10 μm.

[0008] Furthermore, the thickness of the mixed titanium layer is 0.5 to 1 mm, the thickness of the spherical dehydrogenated titanium powder layer is 0.1 to 0.3 mm, the thickness of the functional coating layer is 0.2 to 0.5 mm, and the thickness of the stainless steel plate is 0.5 to 1 mm.

[0009] Additionally, the stainless steel model numbers include 304, 316, or 316L.

[0010] The present invention further provides a method for manufacturing a PEM water electrolysis bipolar plate, comprising the steps of: Step (1): A through-slit structure is fabricated in a stainless steel plate, and the position of the through-slit structure corresponds to the position of the flow ridge of the bipolar plate and is parallel to each other, followed by pre-treatment. Step (2): The mixed titanium layer slurry is applied with a squeegee to the front and back surfaces of the plate material treated in step (1), filling the through slits. Step (3): Dry and heat press the stainless steel so that the titanium-containing slurry is tightly packed between the surface of the stainless steel and the through slits, thereby obtaining a metal composite plate. Step (4): Using a plasma spraying method, spherical dehydrogenated titanium powder is sprayed onto the surface of the metal composite plate to form a spherical dehydrogenated titanium powder layer. Step (5): Using embossing printing, the functional coating layer slurry is printed onto the spherical titanium dioxide powder layer to form a flow field structure. The flow field structure here refers to a broad definition of flow field structure, including, but not limited to, flow field reaction areas (channel ridges and channel grooves). For example, it also includes the inlet / outlet frames, sealing frames, etc. of bipolar plates (hydrogen-oxygen frames), flow field distribution areas, bridge areas, or turbulent flow areas. Those skilled in the art can create various structures using embossing printing according to their actual needs. Step (6): Dry and demold to obtain a water electrolysis bipolar plate.

[0011] Furthermore, the slurry of the mixed titanium layer and the slurry of the functional coating layer are both titanium-containing slurries, and the titanium-containing slurry includes spherical atomized titanium powder having a particle size of 20 to 50 μm, a solvent, a binder, and a plasticizer, and the mass ratio of the spherical atomized titanium powder, solvent, binder, and plasticizer is 60-80:15-35:3-4:1-2.

[0012] Furthermore, the solvent includes at least one of ethyl alcohol, toluene, or methanol, the binder includes at least one of polyvinyl butyral resin or acrylic resin, and the plasticizer includes at least one of dioctyl phthalate, dibutyl phthalate, or propylene glycol polyester oxalate.

[0013] Furthermore, the conditions for the plasma spraying method are a plasma enthalpy of 22 to 50 MJ / kg, a spraying speed of 600 to 1000 mm / s, and a spraying temperature of 150 to 200°C.

[0014] Furthermore, in the steps (3) and (6), the drying temperature is 100 to 150°C, the drying time is 3 to 5 minutes, and the heat and pressure conditions are a pressure of 0.1 to 4 MPa, a pressure holding time of 120 to 180 seconds, and a heat and pressure temperature of 60 to 150°C.

[0015] Furthermore, the pretreatment method in step (1) includes polishing the stainless steel plate having the through-slit structure formed thereon in stages, then polishing it to a finish and washing it with clean water.

[0016] Furthermore, the surface of the stainless steel plate is polished in stages using sandpaper with a mesh size of 500 to 1200.

[0017] Furthermore, the stainless steel plate surface is polished in stages using sandpaper with grit sizes of 500, 700, 900, and 1200, respectively.

[0018] Furthermore, in step (5), the titanium-containing slurry is printed onto the spherical dehydrogenated titanium powder layer using a embossing printing method to form a functional coating layer with a flow field structure including flow channel ridges, turbulent columns, and hydrogen-oxygen flames on the bipolar plate. The method involves arranging a plurality of capillaries parallel to and spaced apart on the surface of the spherical dehydrogenated titanium powder layer, with one end of the capillaries corresponding to the hydrogen-oxygen chamber of the bipolar plate and the other end corresponding to the turbulent area. A mold is then placed parallel to one side of the spherical dehydrogenated titanium powder layer, and the functional mixed slurry is printed onto the spherical dehydrogenated titanium powder layer in accordance with the shape of the mold, forming a functional coating layer with flow channel ridges, turbulent columns, and hydrogen-oxygen flames on the bipolar plate, which surface becomes the front surface of the bipolar plate.

[0019] The mold further includes an openwork portion and a closed portion, through which the functional mixed slurry passes to form the flow ridges, turbulent columns, and hydrogen-oxygen flames of the bipolar plate. The closed portion shields the portions of the bipolar plate that are not required to form the flow field structure, forming the flow grooves of the bipolar plate, the portions of the turbulent area other than the turbulent columns, and the processing area for the subsequent hydrogen-oxygen chamber. The capillaries are positioned at positions corresponding to the openwork portions, and after printing is completed, the capillaries are removed to form a pore structure, i.e., a bridge area, between the hydrogen-oxygen chamber and the turbulent area, allowing material to pass in and out.

[0020] Furthermore, the manufacturing method of the present invention is used for mass production of water electrolysis bipolar plates, and includes processes such as milling, polishing, slurry mixing, slurry filling, drying and hot pressing, plasma spraying, composite plate cutting, mold installation, slurry printing, drying and demolding, etc. The connections between each process are automated by a robot arm or mechanical driving module, and the capillary installation is performed with high precision by the mechanical driving module, with a position error of 0.01 to 0.05 mm. The mechanical driving module mainly consists of a custom jig, a transmission shaft, a robot arm, an automation control system, etc.

[0021] In the present invention, furthermore, cutting of the composite plate is carried out by a laser cutting machine, which is used to cut out the hydrogen and oxygen chambers of the bipolar plate. [Effects of the Invention]

[0022] The present invention has the following advantageous effects.

[0023] 1. High Stability: According to the present invention, the stainless steel plate is perforated to form parallel and aligned through-slits corresponding to the flow ridges of the bipolar plate. The stainless steel plate is then coated on both sides with a titanium-containing slurry, which is then filled into the through-slits and then dried and hot-pressed. This completely coats the unstable stainless steel plate, and the titanium-containing slurry is then applied to both sides of the stainless steel plate with a squeegee. The titanium-containing slurry is then tightly packed not only on the surface but also inside the stainless steel plate, ensuring airtightness. The titanium-mixed layers on both sides of the stainless steel plate are connected by the through-slits to form an integral structure, making the titanium layer less likely to fall off. Furthermore, pressing using a press strengthens the bonding strength between the membranes on both sides of the stainless steel plate and the substrate, improving durability and significantly enhancing the stability of the water electrolysis bipolar plate.

[0024] 2. High durability and conductivity: The ridge portion of the bipolar plate is in direct contact with the membrane electrode, which is the core of the reaction and has fluctuating potentials and a localized acidic environment. Therefore, the side of the metal plate in contact with the membrane electrode is in direct contact with the high potential and acidic aqueous solution. However, according to the structure of the present invention, the portion of the bipolar plate corresponding to the ridge is made of pure titanium, which has excellent conductivity and stability. The lower layer of the pure titanium is coated with a functional coating, which provides greater strength and durability. This allows the bipolar plate to maintain high conductivity while also having greater durability compared to conventional single-structure bipolar plates.

[0025] 3. High performance: This invention uses low-cost stainless steel as the substrate, then physically modifies the stainless steel substrate using a titanium-containing slurry. This means that a solid substrate layer is first formed, and a small amount of titanium material is simultaneously added to reduce the substrate's resistance. Next, a spherical dehydrogenated titanium powder layer is uniformly sprayed onto the mixed titanium layer using ion spraying. Using powdered titanium material and a finely controlled ion spraying method, a uniform, thin layer of pure titanium is formed, further reducing costs while effectively improving overall conductivity and durability. Finally, a functional coating layer containing titanium powder is used to fabricate a flow field structure, achieving the goals of cost reduction while meeting performance requirements. Therefore, compared to a bipolar plate with a pure titanium structure of a certain thickness, the present invention is manufactured by doping titanium powder or by forming a thin layer of titanium powder, and these methods are used according to the purpose. For example, the method of doping titanium powder is used in modifying the substrate and forming the flow field structure, because the main purpose of these processes is to form a substrate and flow field structure with stable structures, and doping with a relatively small amount of titanium in these processes can achieve cost reduction. On the other hand, the purpose of densely spraying a thin layer of pure titanium between the substrate layer and the flow field structure is to ensure overall performance.

[0026] 4. Simple Manufacturing Process: In this invention, plasma spraying and printing are used to form an integrated titanium layer (spherical dehydrogenated titanium powder layer and functional coating layer) on a stainless steel plate substrate, improving the bipolar plate's electrical conductivity and corrosion resistance while also enabling the integrated production of bipolar plates for water electrolysis. In conventional manufacturing processes, the separator and hydrogen / oxygen frame are machined separately and then glued together to form the bipolar plate. However, the adhesive can affect the adhesive strength and integrity, which can affect the resistance and airtightness of the bipolar plate. In this invention, the bipolar plate structure is directly fabricated on the stainless steel plate, and after forming the titanium layer by plasma spraying, the hydrogen / oxygen chamber structure is subsequently printed using a mold. This achieves bipolar plate sealing without the need for additional adhesive or welding processes, significantly improving production efficiency and reducing costs.

[0027] 5. In this invention, a layer of spherical dehydrogenated titanium powder is first sprayed onto the surface of the composite plate using plasma spraying. Due to the high temperatures generated during the plasma spraying process, the particles on the plate surface melt. The sprayed titanium particles then penetrate the plate surface, resulting in a more densely packed titanium particle distribution and a stronger bond between the plate and the titanium layer. Next, a functional coating layer is printed onto the surface of the spherical dehydrogenated titanium powder layer. The micropores in the spherical dehydrogenated titanium powder layer, combined with the printing pressure, effectively enhance the interpenetration of the titanium particles between the two titanium layers, thereby improving the bond between the two, i.e., the bond between the entire titanium layer and the plate. This invention corresponds to batch production of the titanium layer, which provides stronger bonding and improves the conductivity and durability of the bipolar plate. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 2 is a schematic diagram showing the overall configuration of a mold in this embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the arrangement position of capillaries when printing a functional coating layer. [Figure 3] FIG. 1 is a schematic diagram showing a bipolar plate after embossing printing. [Figure 4] FIG. 10 is a cross-sectional view of a turbulent area of ​​a bipolar plate after embossing printing. [Figure 5] FIG. 2 is a schematic diagram showing the structure of a metal composite plate. [Figure 6] 1 is a flowchart illustrating the mass production process of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention will now be described in more detail with reference to the drawings.

[0030] [Example 1] Preparation of titanium-containing slurry: 60 g of spherically atomized titanium powder with a particle size of 20 μm (spherically atomized titanium powder obtained by atomization processing, produced by a method commonly used in the art), 35 g of absolute ethyl alcohol, 4 g of polyvinyl butyral resin, and 1 g of dioctyl phthalate were weighed and placed in a beaker, and stirred uniformly using a mechanical stirrer, and then prepared for use.

[0031] A 0.5mm thick 304 stainless steel plate with an area of ​​20cm x 10cm was cut and perforated using a milling machine to form a parallel structure of multiple through slits in the plate. The positions of the through holes (through slits) corresponded to the flow ridge 6 of the subsequent bipolar plate and were parallel to the flow ridge 6 of the bipolar plate. Next, the plate was polished stepwise using 200-500 grit sandpaper. The stainless steel plate 5-2-2 was then placed in an acetone solution and ultrasonically cleaned three times for 10 minutes each time. After cleaning, it was washed with ultrapure water and then removed and dried.

[0032] A titanium-containing slurry is evenly squeegee coated onto the front and back surfaces of stainless steel plate 5-2-2 to form mixed titanium layers 5-1, filling the through slits. The plate is then placed in a 100°C oven for 5 minutes, then removed. The plate is then placed on a heat press platform and heat-pressed at a pressure of 4 MPa, a pressure holding time of 120 seconds, and a heat pressing temperature of 150°C to produce metal composite plate 11. The mixed titanium layers 5-1 on both surfaces of metal composite plate 11 are 1 mm thick. The metal composite plate 11 with the mixed titanium layer was then placed on a plasma spraying platform, and the spraying conditions were 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 (spherical dehydrogenated titanium powder obtained by a dehydrogenation process and produced by a method commonly used in the art) was sprayed onto the surface of the mixed titanium layer of the metal composite plate 11, resulting in a spherical dehydrogenated titanium powder layer 10 with pores 100 nm in diameter. The layer was then cut with a laser cutting machine to form hydrogen-oxygen chambers 4. Then, as shown in Figures 2 and 4, multiple capillaries 3 are arranged parallel to and spaced apart from each other on the surface of the spherical dehydrogenated titanium powder layer 10, with one end of the capillaries 3 corresponding to the hydrogen / oxygen chamber 4 of the bipolar plate and the other end of the capillaries 3 corresponding to the turbulent flow area 7.A mold is then placed parallel to the front surface of the spherical dehydrogenated titanium powder layer 10, and a titanium-containing slurry is printed onto the spherical dehydrogenated titanium powder layer 10 along the shape of the mold to form a functional coating layer 9. As shown in Figures 1 and 3, the mold includes an open section 1 and a closed section 2. The open section 1 is for the titanium-containing slurry to pass through and form the required bipolar plate structure, i.e., the bipolar plate's plate flow channel ridges 6, turbulent column, and hydrogen-oxygen frame (the hydrogen-oxygen frame is the peripheral frame of the hydrogen-oxygen chamber 4 and the sealing groove for sealing the periphery of the bipolar plate). The closed section 2 is for shielding the parts that are not required to form the bipolar plate structure, i.e., the bipolar plate's flow channel grooves 5, the parts other than the turbulent column in the turbulent area 7, and the hydrogen-oxygen chamber 4 (for hydrogen and oxygen to enter and exit the bipolar plate, respectively).As shown in Figures 2 and 4, the capillaries 3 correspond to the openwork portions 1 of the mold, allowing the titanium-containing slurry to pass through and print. After printing, a material inlet / outlet 8 is formed between the hydrogen / oxygen chamber and the turbulent flow area, allowing hydrogen to flow from the hydrogen / oxygen chamber into the flow field through the material inlet / outlet 8 and then out of the flow field into the outlet hydrogen / oxygen chamber, i.e., the bridge area. The mold is 0.3 mm thick. The printed metal composite plate is then placed in an oven at 100°C for 5 minutes of heat treatment, then removed and demolded. The capillaries 3 are then removed to obtain a water electrolysis bipolar plate.

[0033] In the method for producing a bipolar plate for water electrolysis of the present invention, the cutting step of the composite plate may be performed later. That is, after removing the capillaries 3, the composite plate is cut using a laser cutting machine to form the hydrogen / oxygen chambers 4, thereby obtaining a bipolar plate for water electrolysis.

[0034] The present invention has a simple process, injecting titanium slurry through a 5-2-2 stainless steel plate. Test results show that the contact resistance of the manufactured bipolar plate is 0.77 mΩ cm. 2 The corrosion current density is 4.15 μA / cm 2 In the present invention, the ridges of the bipolar plate corresponding to the stainless steel penetrations, i.e., the portions corresponding to the ridges of the entire bipolar plate for water electrolysis, are all made of titanium slurry 5-2-1, which directly corresponds to the membrane electrodes during assembly, so that the manufactured bipolar plate for water electrolysis has high performance and conductivity.

[0035] [Example 2] Preparation of titanium-containing slurry: 70 g of spherical atomized titanium powder with a particle size of 35 μm, 20 g of absolute ethyl alcohol, 3.5 g of polyvinyl butyral resin, and 1.5 g of dioctyl phthalate were weighed and placed in a beaker, and stirred uniformly using a mechanical stirrer, and then prepared for use.

[0036] A 0.75mm thick 304 stainless steel plate with an area of ​​20cm x 10cm was cut and milled using a milling machine to form a plurality of parallel slits on the plate, with the positions of the slits corresponding to the positions of the flow ridges 6 of the subsequent bipolar plate and parallel to the flow ridges 6 of the bipolar plate. The plate was then polished in stages using 200-500 grit sandpaper. The stainless steel plate 5-2-2 was then placed in an acetone solution and ultrasonically cleaned three times for 10 minutes each time. After cleaning, it was rinsed with ultrapure water and then removed and dried.

[0037] A titanium-containing slurry was uniformly squeegee-coated onto the front and back surfaces of a stainless steel plate (5-2-2) to form a mixed titanium layer (5-1) and fill the through-slit structure. The plate was then placed in a 100°C oven for 5 minutes, then removed. The plate was then placed on a hot press platform and hot pressed at a pressure of 4 MPa, a pressure hold time of 150 seconds, and a hot pressing temperature of 100°C, resulting in a metal composite plate (11). The mixed titanium layers (5-1) on both the front and back surfaces of the metal composite plate (11) were 1 mm thick. The metal composite plate (11) with the mixed titanium layer was then placed on a plasma spraying platform. The spraying conditions were set to a plasma enthalpy of 36 MJ / kg, a spraying speed of 800 mm / s, and a spraying temperature of 175°C. Spherical dehydrogenated titanium powder with a particle size of 60 μm was sprayed onto the surface of the mixed titanium layer of the metal composite plate (11), resulting in a spherical dehydrogenated titanium powder layer (10). The hydrogen-oxygen chambers 4 were then cut using a laser cutting machine. As shown in Figures 2 and 4, multiple parallel capillaries 3 were placed on the surface of the spherical dehydrogenated titanium powder layer 10 at spaced intervals, with one end of each capillary 3 corresponding to the hydrogen-oxygen chambers 4 of the bipolar plate and the other end corresponding to the turbulent flow area 7. A mold was then placed parallel to the front surface of the spherical dehydrogenated titanium powder layer 10, and a titanium-containing slurry was printed onto the spherical dehydrogenated titanium powder layer 10 along the mold's contour to form a functional coating layer 9. The mold used in this example had the same structure as in Example 1, and its thickness was 0.4 mm. The printed metal composite plate was placed in an oven at 125°C for 4 minutes of heat treatment, then removed and demolded. The capillaries 3 were then removed to obtain a water electrolysis bipolar plate.

[0038] According to the test results, the bipolar plate for water electrolysis manufactured in this example has high performance, and its contact resistance and corrosion current density are 0.73 mΩ·cm, respectively. 2 , 4.23 μA / cm 2 is.

[0039] [Example 3] Preparation of titanium-containing slurry: 80 g of spherical atomized titanium powder with a particle size of 50 μm, 15 g of absolute ethyl alcohol, 3 g of polyvinyl butyral resin, and 1 g of dioctyl phthalate were weighed and placed in a beaker, and stirred uniformly using a mechanical stirrer, and then prepared for use.

[0040] A 1mm thick 316 stainless steel plate with an area of ​​20cm x 10cm was cut and milled using a milling machine to form a plurality of parallel slits in the plate, the positions of which correspond to the positions of the flow ridges 6 of the subsequent bipolar plate and are parallel to the flow ridges 6 of the bipolar plate. The plate was then polished in stages using 200-500 grit sandpaper. The stainless steel plate 5-2-2 was then placed in an acetone solution and ultrasonically cleaned three times for 10 minutes each time. After cleaning, it was washed with ultrapure water and then removed and dried.

[0041] A titanium-containing slurry was uniformly applied to the front and back surfaces of a stainless steel plate (5-2-2) using a squeegee to form a mixed titanium layer (5-1), filling the through-slit structure. The plate was then placed in a 100°C oven for 5 minutes before being removed. The plate was then placed on a hot press platform and hot pressed at a pressure of 4 MPa, a pressure holding time of 180 seconds, and a hot pressing temperature of 60°C, resulting in a metal composite plate (11). The mixed titanium layers (5-1) on both the front and back surfaces of the metal composite plate (11) were 1 mm thick. The metal composite plate (11) with the mixed titanium layer was then placed on a plasma spraying platform. The spraying conditions were set to a plasma enthalpy of 50 MJ / kg, a spraying speed of 1000 mm / s, and a spraying temperature of 200°C. Spherical dehydrogenated titanium powder with a particle size of 100 μm was sprayed onto the surface of the mixed titanium layer of the metal composite plate (11), resulting in a spherical dehydrogenated titanium powder layer (10). The hydrogen-oxygen chambers 4 were then formed by cutting using a laser cutting machine. As shown in Figures 2 and 4, multiple capillaries 3 were arranged parallel to and spaced apart from one another on the surface of the spherical dehydrogenated titanium powder layer 10, with one end of each capillary 3 corresponding to the hydrogen-oxygen chambers 4 of the bipolar plate and the other end corresponding to the turbulent flow area 7. A mold was then placed parallel to the front surface of the spherical dehydrogenated titanium powder layer 10, and a titanium-containing slurry was printed onto the spherical dehydrogenated titanium powder layer 10 along the mold's contour to form a functional coating layer 9. The mold used in this example had the same structure as in Example 1, and its thickness was 0.5 mm. The printed metal composite plate was placed in an oven at 150°C for 3 minutes of heat treatment, then removed and demolded. The capillaries 3 were then removed to obtain a water electrolysis bipolar plate.

[0042] According to the test results, the bipolar plate for water electrolysis manufactured in this example has high performance, and its contact resistance and corrosion current density are 0.71 mΩ·cm, respectively. 2 and 4.14 μA / cm 2 is.

[0043] [Comparative Example 1 (spraying directly onto stainless steel plate 5-2-2 without perforation processing)] Preparation of titanium-containing slurry: 60 g of spherical atomized titanium powder with a particle size of 20 μm, 35 g of anhydrous ethyl alcohol, 4 g of polyvinyl butyral resin, and 1 g of dioctyl phthalate were weighed out and placed in a beaker, and the mixture was stirred uniformly using a mechanical stirrer for use.

[0044] A 0.5mm thick 304 stainless steel plate with an area of ​​20cm x 10cm was cut and polished in stages using 200-500 grit sandpaper. The plate was then placed in an acetone solution and ultrasonically cleaned three times for 10 minutes each time. After cleaning, it was washed with ultrapure water, removed, and dried.

[0045] The cleaned stainless steel plate 5-2-2 was placed on a plasma spraying platform. The spraying conditions were set to a plasma enthalpy of 22 MJ / kg, a spraying speed of 600 mm / s, and a spraying temperature of 150°C. 30 μm spherical dehydrogenated titanium powder was sprayed onto the surface of the stainless steel to form a spherical dehydrogenated titanium powder layer 10. As shown in Figures 2 and 4, a number of capillaries 3 were then placed parallel to the surface of the spherical dehydrogenated titanium powder layer 10, with one end of each capillary 3 corresponding to the hydrogen-oxygen chamber 4 of the bipolar plate and the other end corresponding to the turbulent flow area 7. A mold was then placed parallel to the front surface of the spherical dehydrogenated titanium powder layer 10, and the slurry was printed onto the spherical dehydrogenated titanium powder layer 10 according to the shape of the mold to form a functional coating layer 9. The mold used had the same structure as in Example 1, and the mold thickness was 0.3 mm. The printed stainless steel plate was placed in an oven at 100°C for heat treatment for 5 minutes, and then removed and demolded. The capillaries 3 were then removed to obtain a water electrolysis bipolar plate.

[0046] In this comparative example, a spherical dehydrogenated titanium powder layer 10 is formed directly on the surface of the stainless steel by plasma spraying, and then a titanium-containing slurry is printed to form a titanium protective layer on the surface of the stainless steel. This results in a relatively small contact resistance, 0.12 mΩ·cm compared to Example 1. 2In Example 1, the stainless steel was pierced, filled with titanium-containing slurry, and then subjected to hot pressing, resulting in a denser titanium layer on the surface. Furthermore, in Example 1, the piercing position, i.e., the position of the flow field ridge of the bipolar plate, was entirely made of titanium material, resulting in a lower contact resistance. In this comparative example, a titanium-containing functional coating layer was simply formed on the surface of the stainless steel, resulting in a contact resistance of 0.12 mΩ·cm compared to Example 1. 2 It will become more expensive.

[0047] [Table 1]

[0048] The present embodiment is merely an explanation of the present invention and does not limit the present invention. After reading this specification, a person skilled in the art may make modifications to the present embodiment as necessary without making a creative contribution, but any modifications will be protected by patent law as long as they do not deviate from the scope of the claims of the present invention.

[0049] (Addendum) (Appendix 1) a PEM water electrolysis bipolar plate comprising a stainless steel plate as a substrate, the substrate having through slit structures that correspond to the positions of flow path ridges and are parallel to each other, a mixed titanium layer formed on both the upper and lower surfaces of the substrate, the mixed titanium layer filling the through slit structures and connecting the upper and lower surfaces of the mixed titanium layer, a layer of spherical dehydrogenated titanium powder and a functional coating layer formed in that order on the surface of the mixed titanium layer, the functional coating layer forming a flow field structure of the bipolar plate, and both the mixed titanium layer and the functional coating layer containing spherical atomized titanium powder.

[0050] (Appendix 2) 2. A PEM water electrolysis bipolar plate according to claim 1, wherein the spherical atomized titanium powder has a particle size of 20 to 50 μm, the spherical dehydrogenated titanium powder has a particle size of 30 to 100 μm, micropores are distributed in the spherical dehydrogenated titanium powder layer, and the pore diameters of the micropores are 100 nm to 10 μm.

[0051] (Appendix 3) 2. The PEM water electrolysis bipolar plate according to claim 1, wherein the mixed titanium layer has a thickness of 0.5 to 1 mm, the spherical dehydrogenated titanium powder layer has a thickness of 0.1 to 0.3 mm, the functional coating layer has a thickness of 0.2 to 0.5 mm, and the stainless steel plate has a thickness of 0.5 to 1 mm.

[0052] (Appendix 4) (1) manufacturing a through-slit structure in a stainless steel plate, and aligning the position of the through-slit structure with the position of the channel ridge of the bipolar plate and parallel to each other, and then performing pre-treatment; Step (2) of applying the mixed titanium layer slurry to the front and back surfaces of the plate material treated in step (1) with a squeegee to fill the through slits; Step (3) of drying and hot pressing to obtain a metal composite plate; (4) spraying the spherical dehydrogenated titanium powder onto the surface of the metal composite plate using a plasma spraying method to form a spherical dehydrogenated titanium powder layer; (5) using a embossing printing method to print the slurry of the functional coating layer onto the spherical dehydrogenated titanium powder layer to form a flow field structure; and (6) drying and demolding to obtain a PEM water electrolysis bipolar plate.

[0053] (Appendix 5) 5. The method for producing a PEM water electrolysis bipolar plate according to claim 4, wherein the slurry for the mixed titanium layer and the slurry for the functional coating layer are both titanium-containing slurries, the titanium-containing slurry containing spherically atomized titanium powder having a particle size of 20-50 μm, a solvent, a binder, and a plasticizer, and the mass ratio of the spherically atomized titanium powder, solvent, binder, and plasticizer is 60-80:15-35:3-4:1-2.

[0054] (Appendix 6) Supplementary note 5. The method for manufacturing a PEM water electrolysis bipolar plate according to Supplementary note 5, wherein the solvent includes at least one of ethyl alcohol, toluene, and methanol, the binder includes at least one of polyvinyl butyral resin and acrylic acid resin, and the plasticizer includes at least one of dioctyl phthalate, dibutyl phthalate, and propylene glycol polyester oxalate.

[0055] (Appendix 7) 5. The method for producing a PEM water electrolysis bipolar plate according to claim 4, wherein the plasma spraying conditions are a plasma enthalpy of 22 to 50 MJ / kg, a spraying speed of 600 to 1000 mm / s, and a spraying temperature of 150 to 200°C.

[0056] (Appendix 8) 5. The method for producing a PEM water electrolysis bipolar plate according to claim 4, wherein in the steps (3) and (6), the drying temperature is 100 to 150°C, and the hot pressing conditions are a pressure of 0.1 to 4 MPa, a pressure holding time of 120 to 180 s, and a hot pressing temperature of 60 to 150°C.

[0057] (Appendix 9) 5. The method for producing a PEM water electrolysis bipolar plate according to claim 4, wherein the pretreatment in step (1) comprises polishing a stainless steel plate having a through-slit structure in stages, followed by polishing and rinsing with clean water.

[0058] (Appendix 10) 5. The method for producing a PEM water electrolysis bipolar plate according to claim 4, wherein the connections between each step are automated by a robot arm or a mechanical drive module. [Explanation of symbols]

[0059] 1. Watermark part 2.Occluded part 3. Thin tubules 4. Hydrogen and oxygen chamber 5. Flow channel 6. Channel ridge 7. Turbulence area 8. Material entrance / exit 9. Functional coating layer 10. Spherical dehydrogenated titanium powder layer 11, Metal composite plate 5-1, mixed titanium layer 5-2, composite layer 5-2-1, Titanium slurry 5-2-2, Stainless steel plate 6-1. Milling through-hole processing 6-2. Polishing finish 6-3. Slurry mixing 6-4. Slurry filling 6-5. Drying and heat pressing 6-6. Plasma spraying 6-7. Cutting composite boards 6-8. Mold installation 6-9. Slurry printing 6-10, Drying and demolding

Claims

1. a PEM water electrolysis bipolar plate comprising a stainless steel plate as a substrate, the substrate having through slit structures that correspond to the positions of flow path ridges and are parallel to each other, a mixed titanium layer formed on both the upper and lower surfaces of the substrate, the mixed titanium layer filling the through slit structures and connecting the upper and lower surfaces of the mixed titanium layer, a spherical dehydrogenated titanium powder layer and a functional coating layer formed in that order on the surface of the mixed titanium layer, the functional coating layer forming a flow field structure of the bipolar plate, and both the mixed titanium layer and the functional coating layer containing spherical atomized titanium powder.

2. 2. The PEM water electrolysis bipolar plate according to claim 1, wherein the spherical atomized titanium powder has a particle size of 20 to 50 μm, the spherical dehydrogenated titanium powder has a particle size of 30 to 100 μm, micropores are distributed in the spherical dehydrogenated titanium powder layer, and the pore diameters of the micropores are 100 nm to 10 μm.

3. 2. The PEM water electrolysis bipolar plate according to claim 1, wherein the mixed titanium layer has a thickness of 0.5 to 1 mm, the spherical dehydrogenated titanium powder layer has a thickness of 0.1 to 0.3 mm, the functional coating layer has a thickness of 0.2 to 0.5 mm, and the stainless steel plate has a thickness of 0.5 to 1 mm.

4. Step (1): manufacturing a through-slit structure in a stainless steel plate, and aligning the position of the through-slit structure with the position of the channel ridge of the bipolar plate and parallel to each other, and then performing pre-treatment; Step (2) applying the mixed titanium layer slurry to the front and back surfaces of the plate material treated in step (1) with a squeegee to fill the through slits; Step (3) of drying and hot pressing to obtain a metal composite plate; (4) spraying spherical dehydrogenated titanium powder onto the surface of the metal composite plate using a plasma spraying method to form a spherical dehydrogenated titanium powder layer; Step (5) of printing the slurry of the functional coating layer onto the spherical dehydrogenated titanium powder layer using embossing printing method to form a flow field structure; and (6) drying and demolding to obtain a PEM water electrolysis bipolar plate.

5. 5. The method for manufacturing a PEM water electrolysis bipolar plate according to claim 4, wherein the slurry for the mixed titanium layer and the slurry for the functional coating layer are both titanium-containing slurries, the titanium-containing slurry comprising spherically atomized titanium powder having a particle size of 20 to 50 μm, a solvent, a binder, and a plasticizer, and the mass ratio of the spherically atomized titanium powder, solvent, binder, and plasticizer is 60-80:15-35:3-4:1-2.

6. 6. The method for manufacturing a PEM water electrolysis bipolar plate according to claim 5, wherein the solvent includes at least one of ethyl alcohol, toluene, or methanol, the binder includes at least one of polyvinyl butyral resin or acrylic resin, and the plasticizer includes at least one of dioctyl phthalate, dibutyl phthalate, or propylene glycol polyester oxalate.

7. 5. The method for manufacturing a PEM water electrolysis bipolar plate according to claim 4, wherein the plasma spraying conditions are a plasma enthalpy of 22 to 50 MJ / kg, a spraying speed of 600 to 1000 mm / s, and a spraying temperature of 150 to 200°C.

8. 5. The method for producing a PEM water electrolysis bipolar plate according to claim 4, wherein in steps (3) and (6), the drying temperature is 100 to 150°C, and the hot pressing conditions are a pressure of 0.1 to 4 MPa, a pressure holding time of 120 to 180 seconds, and a hot pressing temperature of 60 to 150°C.

9. 5. The method for manufacturing a PEM water electrolysis bipolar plate according to claim 4, wherein the pretreatment in step (1) comprises polishing the stainless steel plate with the through-slit structure in stages, followed by polishing and rinsing with clean water.

10. The method for manufacturing a PEM water electrolysis bipolar plate according to claim 4, wherein the connections between each step are automated by a robot arm or a mechanical drive module.

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