PEM hydrogen production bipolar plate, preparation method thereof and electrolytic cell

Abstract

The invention provides a PEM hydrogen production bipolar plate, a preparation method thereof and an electrolytic bath, and the preparation method of the PEM hydrogen production bipolar plate comprises the following steps: (1) uniformly mixing polytetrafluoroethylene, bisphenol A epoxy resin and a solvent to obtain polytetrafluoroethylene slurry; (2) applying polytetrafluoroethylene slurry to the surface of the flow channel of the cleaned bipolar plate, and then performing heating treatment to form a polytetrafluoroethylene coating on the surface of the flow channel of the bipolar plate; and (3) carrying out laser ablation to remove the polytetrafluoroethylene coating on the surface of the runner ridge of the runner, then carrying out electroplating, and forming a metal coating on the surface of the runner ridge to obtain the PEM hydrogen production bipolar plate. The bipolar plate provided by the invention is simple in preparation process and low in cost, not only effectively reduces the use amount of noble metal, but also avoids oxidation corrosion of the region of the flow channel where the noble metal layer is not formed, prolongs the service life of the bipolar plate, and has excellent electrical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by hydrolysis, and in particular to a PEM hydrogen production bipolar plate, a preparation method thereof, and an electrolytic cell. Background Art

[0002] Proton exchange membrane electrolytic cells (PEM electrolytic cells) can operate at high current densities, have small volumes, high efficiency, high hydrogen production purity, fast response, and can better match renewable energy systems. They are considered to be the most promising hydrogen production technologies by water electrolysis. The bipolar plates of PEM hydrogen production electrolytic cells are mostly made of titanium. In order to avoid the oxidation of titanium and the corrosion attack of fluoride ions in the perfluorosulfonic acid membrane on the titanium material, it is necessary to process a 0.02 - 0.1 mm noble metal platinum or iridium-based coating on the surface of the substrate to improve the corrosion resistance and conductivity of the titanium substrate. However, this significantly increases the production cost of the electrolytic cell and green hydrogen.

[0003] Therefore, at least considering cost factors, the existing bipolar plates need to be improved. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the prior art to some extent. For this reason, an object of the present invention is to provide a PEM hydrogen production bipolar plate, a preparation method thereof, and an electrolytic cell.

[0005] In the first aspect of the present invention, a preparation method of a PEM hydrogen production bipolar plate is provided, and the method includes: (1) Mixing polytetrafluoroethylene, bisphenol A epoxy resin, and a solvent uniformly to obtain a polytetrafluoroethylene slurry; (2) Applying the polytetrafluoroethylene slurry on the surface of the flow channels of the cleaned bipolar plate and then performing heat treatment to form a polytetrafluoroethylene coating on the surface of the flow channels of the bipolar plate; (3) Removing the polytetrafluoroethylene coating on the surface of the flow channel ridges of the flow channels by laser ablation and then performing electroplating to form a metal coating on the surface of the flow channel ridges to obtain a PEM hydrogen production bipolar plate.

[0006] According to the above method for preparing a PEM hydrogen production bipolar plate provided by the present invention, first, a polytetrafluoroethylene (PTFE) slurry is prepared. The polytetrafluoroethylene slurry is applied on the surface of the flow channels of the cleaned bipolar plate and then heat-treated, so as to form a layer of polytetrafluoroethylene coating on the surface of the flow channels of the bipolar plate. Then, the polytetrafluoroethylene coating on the surface of the flow channel ridges of the flow channels is removed by laser ablation to expose the flow channel ridges. Finally, electroplating deposition is used to electroplate the bipolar plate. A metal coating will be deposited on the exposed surface of the flow channel ridges, and the flow channel sides and bottoms of the flow channels cannot form a metal coating because of the formed polytetrafluoroethylene coating, thereby obtaining a PEM hydrogen production bipolar plate with only a metal coating on the surface of the flow channel ridges.

[0007] The present invention only forms a metal coating on the surface of the flow channel ridge, effectively reducing the consumption of precious metals in the PEM hydrogen production bipolar plate and significantly reducing the cost. At the same time, since both the flow channel side and the flow channel bottom surface of the flow channel have a polytetrafluoroethylene coating, the flow channel side and the flow channel bottom of the flow channel are effectively prevented from being oxidized and corroded. In addition, the present invention uses a polytetrafluoroethylene slurry prepared from polytetrafluoroethylene and bisphenol A epoxy resin to prepare the polytetrafluoroethylene coating. The polytetrafluoroethylene coating has good contact with the flow channel surface and is stable and does not fall off in the electrolysis environment of the electrolytic cell, ensuring the normal operation of the bipolar plate. The bipolar plate preparation process provided by the present invention is simple, easy to operate, the materials are easy to obtain, and the cost is low. It not only effectively reduces the usage amount of precious metals, but also avoids the oxidation and corrosion of the area where the precious metal layer is not formed on the flow channel, prolongs the service life of the bipolar plate, and at the same time, the bipolar plate prepared by this method has excellent electrical properties, which are equivalent to those of the existing bipolar plate with a completely covered metal layer on the flow channel surface.

[0008] Those skilled in the art can understand that laser ablation uses a laser etching machine to ablate the PTFE coating on the flow channel ridge according to a set program. Specific parameters can be selected by those skilled in the art according to the actual situation. Further, the bipolar plate after laser ablation is ultrasonically cleaned with ethanol and dried.

[0009] In some embodiments of the present invention, in step (1), the mass ratio of the polytetrafluoroethylene to the bisphenol A epoxy resin is (85 - 95):(3 - 7). Controlling the mass ratio of the polytetrafluoroethylene to the bisphenol A epoxy resin within the above range can ensure that the formed polytetrafluoroethylene coating has good contact with the flow channel surface and avoid the peeling off of the polytetrafluoroethylene coating in the electrolysis environment.

[0010] In some embodiments of the present invention, in step (1), the mass fraction of the polytetrafluoroethylene in the polytetrafluoroethylene slurry is 3% - 8%. Controlling the mass fraction of the polytetrafluoroethylene in the polytetrafluoroethylene slurry within the above range can ensure the uniformity of the polytetrafluoroethylene slurry, facilitate the formation of a uniform polytetrafluoroethylene coating on the flow channel surface, and at the same time facilitate the subsequent heat treatment.

[0011] In some embodiments of the present invention, the solvent includes but is not limited to at least one of N-methylpyrrolidone and methyl isobutyl ketone.

[0012] In some embodiments of the present invention, in step (2), the temperature of the heat treatment is 300 - 380 °C, preferably 360 °C - 370 °C. Controlling the temperature of the heat treatment within the above range can enhance the bonding force between the PTFE coating and the bipolar plate substrate. Further, the heat treatment can be carried out in a heating furnace.

[0013] In some embodiments of the present invention, before the bipolar plate is heat-treated, the bipolar plate is dried to remove organic solvents. Further, the drying temperature is 100°C - 150°C.

[0014] In some embodiments of the present invention, the heat treatment time is 12 - 20 min, preferably 15 min.

[0015] In some embodiments of the present invention, in step (2), the thickness of the polytetrafluoroethylene coating is 0.03 mm - 0.2 mm, preferably 0.05 mm - 0.11 mm. Within the above range of the thickness of the polytetrafluoroethylene coating, effective anti-corrosion of the PTFE coating can be achieved while ensuring the heat transfer effect.

[0016] In some embodiments of the present invention, in step (2), the cleaning method includes: continuously ultrasonically cleaning the bipolar plate in acetone, ethanol, and deionized water for 10 min - 20 min in sequence.

[0017] In some embodiments of the present invention, the application method includes dip coating, spraying, or brushing.

[0018] In some embodiments of the present invention, in step (3), the thickness of the metal coating is 50 μm - 200 μm, preferably 50 μm - 100 μm. Controlling the thickness of the metal coating within the above range can ensure good electrical conductivity of the bipolar plate. Those skilled in the art can understand that electroplating is a conventional process in the art, and those skilled in the art can select specific electroplating conditions according to the actual situation, and no special limitation is made here.

[0019] In some embodiments of the present invention, the metal of the metal coating includes platinum or iridium.

[0020] In the second aspect of the present invention, the present invention provides a PEM hydrogen production bipolar plate prepared by the above method. The PEM hydrogen production bipolar plate has a low cost, excellent electrical properties, and a long service life.

[0021] In the third aspect of the present invention, the present invention provides an electrolytic cell including the above PEM hydrogen production bipolar plate. The electrolytic cell has a low production cost and a long service life.

[0022] The present invention has at least the following beneficial effects: (1) The present invention only forms a metal coating on the surface of the flow channel ridge, effectively reducing the consumption of precious metals in the PEM hydrogen production bipolar plate and significantly reducing the cost. At the same time, since both the flow channel side and the flow channel bottom surface of the flow channel have a polytetrafluoroethylene coating, the flow channel side and the flow channel bottom of the flow channel are effectively prevented from being oxidized and corroded. In addition, the present invention uses a polytetrafluoroethylene slurry prepared from polytetrafluoroethylene and bisphenol A epoxy resin to prepare the polytetrafluoroethylene coating. The polytetrafluoroethylene coating has good contact with the flow channel surface and is stable and does not fall off in the electrolysis environment of the electrolytic cell, ensuring the normal operation of the bipolar plate.

[0023] (2) The bipolar plate preparation process provided by the present invention is simple, easy to operate, the materials are easy to obtain, and the cost is low. It not only effectively reduces the usage amount of precious metals, but also avoids the oxidation and corrosion of the area where the precious metal layer is not formed in the flow channel, prolongs the service life of the bipolar plate. At the same time, the bipolar plate prepared by this method has excellent electrical properties, which are comparable to those of the existing bipolar plate with a completely covered metal layer on the flow channel surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0025] Figure 1 It is a partial structure diagram of the bipolar plate provided by the present invention; Figure 2 It is a diagram of the test results of the electrical properties of the bipolar plates in Example 1-2 and Comparative Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. The following describes the present invention with reference to specific embodiments. It should be noted that these embodiments are only descriptive and do not limit the present invention in any way.

[0027] Example 1 This example provides a bipolar plate, and its specific preparation process is as follows: (1) Clean the bipolar plate: Ultrasonically clean the bipolar plate in acetone, ethanol, and deionized water in sequence for 10 min to remove surface impurities.

[0028] (2) Preparation of PTFE coating: Bisphenol A epoxy resin (BPA-EP) coating was added to an N-methylpyrrolidone solution containing 5% PTFE by mass. The mass ratio of PTFE to bisphenol A epoxy resin was 95:5. After mixing evenly, it was reserved for use. All the bipolar plates after the above cleaning treatment were immersed in the mixed solution, taken out after a period of time, dried to remove the organic solvent, and then placed in a heating furnace for heat treatment at 370 °C for 15 min to form a PTFE coating on the surface of the flow channels. The thickness of the PTFE coating was 0.11 mm.

[0029] (3) Laser ablation: The heat-treated bipolar plates were placed under a laser etching machine, and the PTFE coating on the flow channel ridges was ablated according to the set program. The ablated plates were ultrasonically cleaned with ethanol and dried.

[0030] (4) Electroplating a platinum layer: The treated bipolar plates were electroplated according to the conventional electroplating process to prepare a 100-μm-thick Pt coating. After electroplating, they were taken out, cleaned with deionized water, and the preparation of the bipolar plates with partition coatings was completed.

[0031] The local structure of the bipolar plate 1 prepared in Example 1 can be referred to Figure 1 , Figure 1 in which, a metal coating 3 is formed on the surface of the flow channel ridges of the flow channels, and a PTFE coating 2 is formed on the flow channel sides and the flow channel bottoms of the flow channels.

[0032] Example 2 This example provides a bipolar plate, and its specific preparation process is as follows: (1) Cleaning treatment of the bipolar plate: The bipolar plate was ultrasonically cleaned successively in acetone, ethanol, and deionized water for 10 min to remove surface impurities.

[0033] (2) Preparation of PTFE coating: Bisphenol A epoxy resin (BPA-EP) coating was added to an N-methylpyrrolidone solution containing 5% PTFE by mass. The mass ratio of PTFE to bisphenol A epoxy resin was 95:5. After mixing evenly, it was reserved for use. The above PTFE mixed slurry was sprayed on the bipolar plates after the above cleaning treatment using an ultrasonic spraying device. After spraying, it was taken out and dried, and then placed in a heating furnace for heat treatment at 360 °C for 15 min to form a PTFE coating on the surface of the flow channels. The thickness of the PTFE coating was 0.05 mm.

[0034] (3) Laser ablation: The heat-treated bipolar plates were placed under a laser etching machine, and the PTFE coating on the flow channel ridges was ablated according to the set program. The ablated plates were ultrasonically cleaned with ethanol and dried.

[0035] (4)Iridium plating layer: The treated bipolar plates are plated according to the conventional electroplating process to prepare a 50-μm Ir coating. After electroplating, they are taken out and cleaned thoroughly with deionized water to complete the preparation of the bipolar plates with partition coatings.

[0036] Comparative Example 1 Comparative Example 1 provides a bipolar plate, which is different from that of Example 1 in that Pt coatings with a thickness of 100 μm are formed on the flow channel surfaces of the bipolar plates.

[0037] The performances of the bipolar plates in the examples and comparative examples are tested. The specific test process is as follows: The bipolar plates of the examples and comparative examples are placed in a PEM test electrolytic cell, and polarization curves are tested at 60 °C within a current density range of 0.1 - 2 A / cm 2 range.

[0038] The performance test results of the bipolar plates in the examples and comparative examples are shown in Figure 2 .

[0039] It can be seen from Figure 2 that the current density-voltage curves of the examples and comparative examples almost coincide, indicating that the electrical performances of the bipolar plates in the examples and comparative examples are comparable.

[0040] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the present invention in each example.

Claims

1. A preparation method of a PEM hydrogen production bipolar plate, characterized in that, Comprising: (1) Mixing polytetrafluoroethylene, bisphenol A epoxy resin and a solvent uniformly to obtain a polytetrafluoroethylene slurry; (2) Applying the polytetrafluoroethylene slurry onto the surface of the flow channels of the cleaned bipolar plate and then performing heat treatment to form a polytetrafluoroethylene coating on the surface of the flow channels of the bipolar plate; (3) Removing the polytetrafluoroethylene coating on the surface of the flow channel ridges of the flow channels by laser ablation and then performing electroplating to form a metal coating on the surface of the flow channel ridges, obtaining a PEM hydrogen production bipolar plate.

2. The method according to claim 1, wherein In step (1), the mass ratio of the polytetrafluoroethylene to the bisphenol A epoxy resin is (85 - 95):(3 - 7).

3. The method according to claim 1 or 2, characterized in that, In step (1), the mass fraction of polytetrafluoroethylene in the polytetrafluoroethylene slurry is 3% - 8%; And / or, the solvent includes at least one of N-methylpyrrolidone and methyl isobutyl ketone.

4. The method according to claim 1, wherein In step (2), the temperature of the heat treatment is 300 - 380 °C, preferably 360 °C - 370 °C.

5. The method according to claim 1 or 4, characterized in that, In step (2), the time of the heat treatment is 12 - 20 min, preferably 15 min.

6. The method according to claim 1 or 4, characterized in that, In step (2), the thickness of the polytetrafluoroethylene coating is 0.03 mm - 0.2 mm, preferably 0.05 mm - 0.11 mm.

7. The method according to claim 1 or 4, characterized in that In step (2), the cleaning method includes: continuously ultrasonically cleaning the bipolar plate in acetone, ethanol and deionized water for 10 min - 20 min in sequence; And / or, the applying method includes dip coating, spraying or brush coating.

8. The method according to claim 1, wherein In step (3), the thickness of the metal coating is 50 μm - 200 μm, preferably 50 μm - 100 μm; And / or, the metal of the metal coating includes platinum or iridium.

9. A PEM hydrogen production bipolar plate, characterized in that, Prepared by the method according to any one of claims 1 - 8.

10. An electrolytic cell, characterized in that, Comprising the PEM hydrogen production bipolar plate according to claim 9.

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