A composite bipolar plate for producing hydrogen by electrolysis of water and its preparation method and application

Abstract

The present invention discloses a composite bipolar plate for producing hydrogen by electrolysis of water, and a preparation method and application thereof, including an anode plate and a cathode plate; the anode plate is a titanium anode plate, a platinum coating is arranged on one side of the titanium anode plate, and the other side is combined with the cathode plate; the cathode plate comprises the following components by mass: 18-30 parts of thermosetting modified vinyl resin, 55-80 parts of conductive filler, 2-8 parts of functional auxiliary agent, and 2-8 parts of fiber reinforced material; wherein the thermosetting modified vinyl resin is formed by reacting one or more monomers of unsaturated acrylate, unsaturated crotonate, and unsaturated isocyanate. The present invention adopts a composite graphite plate as a cathode plate to replace the platinum coating on the cathode side of the original bipolar plate, greatly reducing costs, and having good stability, and simple preparation equipment and method; the composite bipolar plate has better strength than a machined graphite plate, better corrosion resistance than a titanium plate, and has higher mechanical strength, lower contact resistance, and excellent performance.

Description

Technical Field

[0001] The present invention relates to the technical field of composite bipolar plates for producing hydrogen by electrolysis of water, and in particular to a composite bipolar plate for producing hydrogen by electrolysis of water, and a preparation method and application thereof. Background Art

[0002] Hydrogen energy is a renewable energy source with a series of advantages such as high calorific value, pollution-free, and renewable. Using renewable energy to generate electricity and then coupling water electrolysis to produce green hydrogen can avoid the use of carbon-containing energy at the source and achieve efficient preparation of "green hydrogen". At present, according to the different electrolytes, water electrolysis hydrogen production is mainly divided into four categories: alkaline solution (ALK) water electrolysis hydrogen production, anion exchange membrane (AEM) water electrolysis hydrogen production, proton exchange membrane (PEM) water electrolysis hydrogen production, solid oxide water electrolysis hydrogen production (SOEC). ALK water electrolysis hydrogen production is currently the most commercialized water electrolysis technology, but it has disadvantages such as low current density, high energy consumption, and slow dynamic response. In addition, the electrolyte KOH is highly corrosive, pollutes the environment, and needs to be replaced regularly. SOEC has a high electrolysis efficiency, and the waste heat generated has a high recovery value, but the key components of SOEC have poor durability and are difficult to adapt to dynamic start and stop.

[0003] AEM and PEM, two types of ion exchange membrane water electrolysis hydrogen production, have the advantages of high working current, fast start and stop, and good coupling with renewable energy sources such as photovoltaics. They are considered to be water electrolysis hydrogen production technologies with great development prospects. At present, ion exchange membrane water electrolysis hydrogen production technology has been demonstrated and applied in the fields of on-site hydrogen production at hydrogen refueling stations, wind power and other renewable energy water electrolysis hydrogen production, energy storage, etc., and has been gradually promoted. However, the high material cost has limited the further development of water electrolysis hydrogen production. At present, most bipolar plates for ion exchange membrane water electrolysis hydrogen production adopt the technical route of platinum plating on both sides of the titanium bipolar plate. The thickness of the platinum layer is more than 100nm, and the amount of precious metals used is high, resulting in the cost of the bipolar plate accounting for about 34% of the electrolyzer system. At the same time, the cathode side has a lower potential and weaker oxidation.

[0004] Patent CN116855990A discloses a TinO 2n-1 A method for preparing a coating and a PEM electrolysis hydrogen production plate, wherein a certain amount of TiO 2 Disperse it in an isopropanol aqueous solution, stir and dissolve it, then use the equal volume impregnation method to impregnate it onto the plate, use polyethylene oxide as a binder, and sinter at high temperature. Finally, put the substrate with the titanium oxide layer into a tube furnace and heat it to reduce it to obtain a substrate with TinO 2n-1 Coated bipolar plates. But TinO 2n-1 The coating has poor stability under the proton exchange membrane water electrolysis conditions of high potential, strong oxidation and high temperature, and the coating will dissolve under long-term operation.

[0005] In addition, composite graphite bipolar plates are also disclosed in the prior art. However, in the preparation process of the graphite plates, thermosetting resins are prepared using monomers such as styrene having a foul odor. The monomers are highly volatile and cause great harm to the human body and the environment. At the same time, the viscosity of the resin is too high, and the strength and corrosion resistance of the prepared graphite plates are relatively poor, and the stability in high temperature environments is poor.

[0006] In summary, it is of great significance to research and develop a bipolar plate for hydrogen production by water electrolysis that has both low cost and high stability. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention provides a composite bipolar plate for producing hydrogen by electrolysis of water and a preparation method and application thereof. A composite graphite plate is used as a cathode plate to replace the platinum coating on the cathode side of the original bipolar plate, which greatly reduces the cost and has good stability. The preparation equipment and method are simple.

[0008] In order to solve the above technical problems, the present invention provides a composite bipolar plate for producing hydrogen by electrolysis of water, comprising an anode plate and a cathode plate;

[0009] The anode plate is a titanium anode plate, one side of the titanium anode plate is provided with a platinum coating, and the other side is combined with the cathode plate;

[0010] The cathode plate comprises the following components in parts by mass: 18-30 parts of thermosetting modified vinyl resin, 55-80 parts of conductive filler, 2-8 parts of functional additives, and 2-8 parts of fiber reinforcement material;

[0011] The thermosetting modified vinyl resin is formed by reacting one or more monomers of unsaturated acrylate, unsaturated crotonate, and unsaturated isocyanate with epoxy resin;

[0012] The thermosetting modified vinyl resin has a viscosity of 400-600 mPa·s at 25° C. and a density of 1.03-1.08 g / cm 3 , solid content is 62-68%.

[0013] The present invention uses a composite graphite plate as a cathode plate to replace the original platinum coating on the cathode side of the bipolar plate, which greatly reduces costs, has good stability and a simple preparation method. The composite graphite plate uses a thermosetting modified vinyl resin, which is formed by reacting one or more monomers of low-volatility unsaturated acrylates, unsaturated butyl esters, and unsaturated isocyanates with epoxy resin, avoiding the use of volatile monomers such as styrene with a foul odor; at the same time, the viscosity of the thermosetting modified vinyl resin at 25°C is 400-600mPa·s, and the density is 1.03-1.08g / cm 3The lower viscosity and density similar to water are conducive to the wetting of the resin with other components, and the interfacial bonding force is stronger. The higher solid content of 62-68% helps to increase the molecular weight of the resin after polymerization, thereby improving the strength.

[0014] Furthermore, the unsaturated acrylate is one or more of methyl methacrylate, hydroxyethyl methacrylate, n-butyl methacrylate, and pentaerythritol triacrylate; the unsaturated butenoate is one or more of methyl 3-butenoate, ethyl 3-butenoate, and sec-butyl butenoate; and the unsaturated isocyanate is one or more of toluene diisocyanate, diphenylmethane diisocyanate, and dicyclohexylmethane diisocyanate.

[0015] Furthermore, the curing time of the thermosetting modified vinyl resin at 120-140° C. is 20-40 seconds, and the molecular weight of the cured resin is 100,000-400,000, and the glass transition temperature is 140-160° C. The curing rate is fast, which improves production efficiency, and the cured resin has a high glass transition temperature, and still maintains high dimensional stability in a high temperature use environment.

[0016] Furthermore, the thickness of the anode plate is 0.2-0.5 mm;

[0017] And / or, the thickness of the cathode plate is 0.2-1.2 mm;

[0018] And / or, both the anode plate and the cathode plate have straight flow channels or serpentine flow channels.

[0019] Furthermore, the conductive filler is one or more of flake graphite, spherical graphite, microcrystalline graphite, expanded graphite, and carbon black, and the carbon content of the conductive filler is ≥99.995%.

[0020] Furthermore, the functional additive is a combination of two or more of sodium stearate, zinc stearate, nano carbon black, nano silver powder, and kaolin. Functional additives can improve the processability (fluidity, shear viscosity, etc.) of the product and improve the performance (conductivity, contact resistance, yield, etc.) of the product.

[0021] Furthermore, the fiber reinforcement material is one or more of chopped carbon fiber, glass fiber, polyetheretherketone fiber, polyphenylene sulfide fiber, polysulfone fiber, and carbon nanotube;

[0022] The length of the fiber is 0.5-4 mm, the diameter is 5-20 μm, and the fiber surface is oxidized by wet oxidation and / or electro-Fenton oxidation.

[0023] The second aspect of the present invention provides a method for preparing the composite bipolar plate for producing hydrogen by electrolysis of water according to the first aspect, comprising the following steps:

[0024] S1. Put the conductive filler, functional additives and fiber reinforcement material into a stirring barrel, stir and pre-disperse, then add the thermosetting modified vinyl resin, and stir and knead for 20-120 minutes with a stirring paddle and a kneading paddle to obtain a composite graphite material;

[0025] The stirring paddle is a sawtooth structure on both sides, and the gap between the saw teeth is 1-3mm, and the front angle of the saw teeth is 45-60°; the kneading paddle is in the shape of a double twist, the gap between the paddle blades is 2-4mm, and the gap between the paddle blade and the barrel wall of the stirring barrel is 0.5-3mm; preferably, the motion trajectories of the stirring paddle and the kneading paddle are both analyzed by digital modeling, and the two are controlled by independent motors and do not contact each other, which can ensure that the motion trajectory in the material barrel has no dead angle and the stirring is uniform;

[0026] S2, molding the composite graphite material onto the uncoated side of the titanium anode plate, and curing at 120-140° C. for 20-50 seconds to form a composite bipolar plate in which a platinum coating, a titanium anode plate and a composite cathode plate are sequentially stacked;

[0027] S3. Performing plasma treatment or laser sintering treatment on the composite bipolar plate to obtain the composite bipolar plate for producing hydrogen by electrolysis of water.

[0028] Furthermore, the surfaces of the stirring paddle and the kneading paddle are thermally sprayed with zirconium oxide or Teflon coating, and the coating thickness is 20-200 μm and the roughness is ≤0.05 μm.

[0029] Furthermore, before S2, the uncoated side of the anode plate is subjected to surface roughening and corona treatment to remove potential oxide films and improve the bonding strength with materials such as graphite;

[0030] Wherein, after the roughening treatment, the roughness of the non-coated side of the anode plate is 40-70 μm; the roughening method is any one of plasma etching, mechanical grinding, and sandblasting and shot blasting;

[0031] The working gap of the corona treatment is 1-2 mm, and the power is 5-20 kW.

[0032] The third aspect of the present invention provides the use of the composite bipolar plate described in the first aspect in hydrogen production by water electrolysis.

[0033] Beneficial effects of the present invention:

[0034] The present invention adopts a composite graphite plate as a cathode plate to replace the platinum coating on the cathode side of the original bipolar plate, which greatly reduces the cost, has good stability and a simple preparation method. At the same time, the composite graphite plate adopts a thermosetting modified vinyl resin, which is formed by reacting one or more monomers of low-volatility unsaturated acrylates, unsaturated butyl esters, and unsaturated isocyanates with epoxy resin, avoiding the damage to the human body and the environment caused by the use of volatile monomers such as styrene with a foul odor; the other components of the thermosetting modified vinyl resin have good wettability, greater interfacial bonding force, and a higher solid content that helps to increase the molecular weight of the resin after polymerization, thereby increasing the strength.

[0035] The thermosetting modified vinyl resin used in the composite graphite plate of the present invention has a large number of active functional groups, such as unsaturated double bonds and oxygen-containing functional groups. During the curing process, the resin functional groups and the functional groups on the surface of the anode plate are mutually anchored, which can improve the bonding force between the graphite plate and the anode plate; at the same time, the surface of the anode plate is roughened and corona treated to increase the roughness, form a larger specific surface area, increase the oxygen-containing functional groups such as carboxyl and carbonyl on the metal surface, and further improve the bonding force between the two.

[0036] The composite bipolar plate of the graphite cathode plate / titanium anode plate of the present invention has better strength than the machined graphite plate, better corrosion resistance than the titanium plate, higher mechanical strength, lower contact resistance and excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 This is a schematic diagram of the working principle of the composite bipolar plate for producing hydrogen by electrolysis of water according to the present invention;

[0039] Figure 2 is a photograph of the cathode side of the composite bipolar plate of Example 1 of the present invention;

[0040] Figure 3 is a SEM image of the end surface of the cathode plate of the composite bipolar plate of Example 1 of the present invention;

[0041] Figure 4 This is a SEM image of the cathode plate surface of the composite bipolar plate of Example 1 of the present invention. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Example 1

[0043] This example relates to a preparation method of a composite bipolar plate, including the following steps:

[0044] S1. After separately weighing 0.5 kg (5 parts) of chopped carbon fibers (with a diameter of 15 μm and a length of 1 mm, and the surface treatment method of the carbon fibers is oxidation treatment with Fenton reagent), 7.5 kg of microcrystalline graphite (with a carbon content of 99.995%), 0.2 kg of zinc stearate, and 0.2 kg of nano carbon black and loading them into a stirring cylinder, pre-dispersion is carried out.

[0045] S2. After the pre-dispersion is completed, a thermosetting modified vinyl resin obtained by reacting 2 kg of methyl methacrylate monomer with epoxy resin is transported into the material cylinder by a vacuum pump. The resin viscosity is 420 mPa·s, the density is 1.03 g / cm 3 , the solid content is 65%. At the same time, kneading and stirring are started. Among them, the kneading paddle is in a double-twist shape, the gap between the paddle blades is 3 mm, and the gap between the paddle blade and the barrel wall is 2 mm; the stirring paddle is serrated on the upper and lower sides, the gap between the serrations is 1 mm, the front angle of the serrations is 45°. Both the kneading paddle and the stirring paddle are mirror-polished, with a roughness ≤ 0.05 μm. On the surfaces of the stirring paddle and the kneading paddle, a zirconia coating with the functions of wear resistance and preventing metal ion loss is thermally sprayed, and the coating thickness is 50 μm. The motor powers corresponding to the stirring paddle and the kneading paddle are 2 kW and 3 kW respectively, and the mixing time is 40 min;

[0046] S3. The uncoated side of the anode plate is treated by plasma etching and corona treatment. After the treatment, the surface roughness of the anode plate is 40 - 70 μm. Among them, the working gap of the electrode for corona treatment is 2 mm, and the treatment power is 20 kW. An appropriate amount of the composite graphite material in step S2 is evenly laid on the uncoated side of a titanium plate with a substrate thickness of 0.3 mm, transferred into a mold with a cathode-side flow channel, and molded by pressing. The molding temperature is 140 °C, the molding time is 40 s. After pressure relief and demolding, a small amount of residual graphite powder on the surface of the bipolar plate is removed by compressed air. Among them, the thickness of the graphite layer is 0.3 mm, and both the anode plate and the composite graphite cathode plate have corresponding straight channels or serpentine channels. Finally, the graphite cathode plate in the bipolar plate is subjected to plasma surface treatment to obtain the final bipolar plate product of composite graphite cathode plate / titanium anode plate / platinum coating, as Figure 1 shown. Example 2

[0047] This embodiment relates to a method for preparing a composite bipolar plate, comprising the following steps:

[0048] S1. Weigh 0.4 kg (4 portions) of chopped carbon fiber (20 μm in diameter, 1.5 mm in length, and the surface treatment of the carbon fiber is Fenton reagent oxidation treatment), 6.35 kg of flake graphite (carbon content of 99.995%), 0.2 kg of zinc stearate, and 0.5 kg of nano carbon black into a mixing drum and pre-disperse them.

[0049] S2. After the pre-dispersion is completed, 3 kg of thermosetting modified vinyl resin prepared by reacting 3-butylene acid ethyl ester monomer with epoxy resin is transported into the material barrel by a vacuum pump. The resin viscosity is 450 mpa·s and the density is 1.05 g / cm 3 , solid content is 67%, kneading and stirring are turned on at the same time. Among them, the kneading paddle is double twisted, the gap between the paddles is 3mm, and the gap between the paddles and the barrel wall is 2mm; the stirring paddle is serrated on both sides, the gap between the serrations is 1mm, the sawtooth rake angle is 45°, the kneading paddle and the stirring paddle are mirror polished, the roughness is ≤0.05μm, the surface of the stirring paddle and the kneading paddle is thermally sprayed with zirconium oxide coating that is wear-resistant and blocks the loss of metal ions, the coating thickness is 50μm, the motor power corresponding to the stirring paddle and the kneading paddle is 2kW and 3kW respectively, and the mixing time is 40min;

[0050] S3, the uncoated side of the anode plate is subjected to plasma etching and corona treatment, and the surface roughness of the anode plate after treatment is 40-70μm, wherein the electrode working gap of the corona treatment is 2mm, and the processing power is 20kW. An appropriate amount of the composite graphite material of step S2 is spread on the uncoated side of the titanium plate with a substrate thickness of 0.3mm, transferred to a mold with a cathode side flow channel, and molded. The molding temperature is 140°C, the molding time is 40s, and after the pressure is released and demoulded, a small amount of graphite powder remaining on the surface of the plate is removed with compressed air, wherein the graphite layer thickness is 0.3mm, and the anode plate and the composite graphite cathode plate have corresponding direct current channels or serpentine flow channels. Finally, the graphite cathode plate in the bipolar plate is subjected to plasma surface treatment to obtain the final bipolar plate product. Comparative Example 1

[0051] This comparative example relates to a method for preparing a composite bipolar plate, which differs from Example 1 in that: 6 kg of microcrystalline graphite, 3.5 kg of thermosetting modified vinyl resin prepared from methyl methacrylate monomer and epoxy resin, and other steps and parameters remain unchanged. Comparative Example 2

[0052] This comparative example relates to a method for preparing a composite bipolar plate, which differs from Example 1 in that the viscosity of the thermosetting modified vinyl resin is 700 mPa·s and the density is 1.52 g / cm3 , solid content is 75%, and other steps and parameters remain unchanged. Comparative Example 3

[0053] This comparative example relates to a method for preparing a composite bipolar plate, which differs from Example 1 in that epoxy resin is used to replace the thermosetting modified vinyl resin, wherein the epoxy resin is a composite of bisphenol A epoxy resin and bisphenol S epoxy resin, the mass ratio of the two is 1:1, the epoxy value is 0.20-0.48, and the other steps and parameters remain unchanged. Comparative Example 4

[0054] This comparative example relates to a method for preparing a composite bipolar plate, which differs from Example 1 in that a phenolic resin is used to replace a thermosetting modified vinyl resin, wherein the phenolic resin is prepared from phenol and polyaryl alkyl ether under an alkaline catalytic environment, and other steps and parameters remain unchanged. Comparative Example 5

[0055] This comparative example relates to a method for preparing a composite bipolar plate, which differs from Example 1 in that: the gap between the kneading paddle blades is 5 mm, and the gap between the paddle blades and the barrel wall is 4 mm; the gap between the stirring paddle teeth is 5 mm, and the sawtooth front angle is 100°, and other steps and parameters remain unchanged. Comparative Example 6

[0056] This comparative example relates to a method for preparing a composite bipolar plate, which differs from Example 1 in that the gap between the kneading paddle blades is 1 mm, and the gap between the paddle blades and the barrel wall is 0.3 mm; the gap between the stirring paddle teeth is 0.5 mm, and the sawtooth front angle is 40°, and other steps and parameters remain unchanged. Comparative Example 7

[0057] This comparative example relates to a method for preparing a composite bipolar plate, which differs from Example 1 in that the kneading paddle is of a rectangular door frame type with a plane size of 30 cm×10 cm, and other steps and parameters remain unchanged. Comparative Example 8

[0058] This comparative example relates to a method for preparing a composite bipolar plate, which differs from Example 1 in that the anode plate without a coating layer is not roughened or corona treated, and other steps and parameters remain unchanged. Comparative Example 9

[0059] This comparative example relates to a method for preparing a composite bipolar plate, which differs from Example 1 in that: 1 kg of chopped carbon fiber and 7 kg of microcrystalline graphite are used, and other steps and parameters remain unchanged.

[0060] Test Case

[0061] Figure 2 , Figure 3 , Figure 4The following are the physical image (cathode plate side), the cross-sectional SEM image and the surface SEM image of the bipolar plate prepared in Example 1. Figure 2 It can be seen that the surface of the composite graphite cathode plate is smooth, and there is no uneven pressing or agglomeration, which shows that the cathode plate and the anode plate are well combined and the composite graphite material is well dispersed. Figure 3 It can be seen that there is no agglomeration of fibers in the cross section of the composite graphite cathode plate, indicating excellent dispersion. Figure 4 It can be seen that the surface of the composite graphite cathode plate is smooth, which is consistent with the observation results of the actual image.

[0062] The bending strength and contact resistance of the bipolar plates of Examples 1-2 and Comparative Examples 1-4 and Comparative Examples 8-9 are shown in Table 1.

[0063] Table 1

[0064]

[0065] As can be seen from Table 1, the bipolar plates prepared in Example 1 and Example 2 have both excellent bending strength and low contact resistance.

[0066] Compared with Example 1, more resin is added in Comparative Example 1, which makes the bipolar plate have higher mechanical strength, but excessive resin will also increase the contact resistance of the bipolar plate and reduce the performance of the electrolytic cell. Contact resistance exceeds 10mΩ·cm 2 , does not meet the use requirements of bipolar plates (≤10mΩ·cm 2 ).

[0067] Comparative Example 2 uses a resin with higher viscosity and solid content, which makes the dispersion of the composite material difficult on the one hand, and on the other hand, the resin with higher viscosity and solid content will cut off more conductive networks during curing, causing an increase in the contact resistance of the bipolar plate.

[0068] The resins used in Comparative Examples 3 and 4 are epoxy resin and phenolic resin, respectively, and their solid contents are similar to those of the resin used in Example 1. However, compared with the resin used in Example 1 of the present invention, the resin used in Example 1 has better wettability with materials such as conductive fillers, and is therefore easier to disperse. The resin molecular chains are more flexible, and can reduce damage to the conductive network while meeting the mechanical strength requirements, thereby achieving a balance between conductivity and strength and meeting usage requirements. However, epoxy resin and phenolic resin have weak wettability with conductive fillers, and their molecular chains are more rigid. Under the premise of the same content, more conductive networks will be cut off, resulting in a sharp increase in contact resistance.

[0069] The titanium plate of Comparative Example 8 was not roughened and corona treated, and the contact resistance was significantly improved. In comparison, after the titanium plate in Example 1 was treated, on the one hand, the roughness was increased, which indirectly increased the contact area between the cathode plate and the anode plate, and effectively improved the interface effect; on the other hand, the surface treatment can increase the number of active functional groups (hydroxyl groups, carboxyl groups), and react physically and chemically with the active functional groups in the resin (unsaturated double bonds, oxygen-containing functional groups), further improving the bonding force of the anode and cathode plates and the bending strength of the bipolar plates. In addition, due to the increase in the contact area between the cathode plate and the anode plate, the contact resistance will decrease accordingly, which is beneficial to improving the performance of the electrolytic cell.

[0070] Comparative Example 9 has a higher carbon fiber content, and the fiber material is very easy to agglomerate. On the one hand, a large amount of carbon fibers cannot play a role in strengthening the strength, and on the other hand, the porosity is increased, the strength is reduced, and the contact resistance is increased.

[0071] The bending strength, contact resistance and dispersion of the bipolar plates of Examples 1-2 and Comparative Examples 5-7 are shown in Table 2.

[0072] Table 2

[0073]

[0074] As shown in Table 2, compared with Example 1, the blade gap, sawtooth gap and chamfer in Comparative Example 5 are larger. When dispersing materials, larger gaps and chamfers will reduce the dispersion effect and affect the mixing effect between materials. However, in Comparative Example 6, when the sawtooth gap and chamfer are smaller, it is more difficult for the material to pass through the blade gap and sawtooth gap, resulting in a poor dispersion effect. In Comparative Example 7, the shape of the kneading paddle is changed from a double twist shape to a door frame paddle, and the dispersion effect is significantly reduced.

[0075] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A composite bipolar plate for producing hydrogen by electrolysis of water, characterized in that: including an anode plate and a cathode plate; The anode plate is a titanium anode plate, one side of the titanium anode plate is provided with a platinum coating, and the other side is combined with the cathode plate; The cathode plate comprises the following components in parts by mass: 18-30 parts of thermosetting modified vinyl resin, 55-80 parts of conductive filler, 2-8 parts of functional additives, and 2-8 parts of fiber reinforcement material; The thermosetting modified vinyl resin is formed by reacting one or more monomers of unsaturated acrylate, unsaturated crotonate, and unsaturated isocyanate with epoxy resin; The thermosetting modified vinyl resin has a viscosity of 400-600 mPa·s at 25° C. and a density of 1.03-1.08 g / cm 3 , solid content is 62-68%; The functional additive is a combination of two or more of sodium stearate, zinc stearate, nano carbon black, nano silver powder, and kaolin; The method for preparing the composite bipolar plate for producing hydrogen by electrolysis of water comprises the following steps: S1. Put the conductive filler, functional additives and fiber reinforcement material into a stirring barrel, stir and pre-disperse, then add the thermosetting modified vinyl resin, and stir and knead for 20-120 minutes with a stirring paddle and a kneading paddle to obtain a composite graphite material; The stirring paddle is a serrated structure with upper and lower surfaces, and the gap between the serrations is 1-3mm, and the front angle of the serrations is 45-60°; the kneading paddle is in the shape of a double twist, the gap between the paddle blades is 2-4mm, and the gap between the paddle blades and the barrel wall of the mixing barrel is 0.5-3mm; S2, molding the composite graphite material onto the uncoated side of the titanium anode plate, and curing at 120-140° C. for 20-50 seconds to form a composite bipolar plate in which a platinum coating, a titanium anode plate and a composite cathode plate are sequentially stacked; S3, subjecting the composite bipolar plate to plasma treatment or laser sintering treatment to obtain the composite bipolar plate for producing hydrogen by electrolysis of water; Before S2, the uncoated side of the anode plate is subjected to surface roughening and corona treatment; Wherein, after the roughening treatment, the roughness of the uncoated side of the anode plate is 40-70 μm; The working gap of the corona treatment is 1-2 mm, and the power is 5-20 kW.

2. The composite bipolar plate for producing hydrogen by electrolysis of water according to claim 1, characterized in that: The curing time of the thermosetting modified vinyl resin at 120-140° C. is 20-40 seconds, and the molecular weight of the cured resin is 100,000-400,000, and the glass transition temperature is 140-160° C.

3. The composite bipolar plate for producing hydrogen by electrolysis of water according to claim 1, characterized in that: The thickness of the anode plate is 0.2-0.5 mm; And / or, the thickness of the cathode plate is 0.2-1.2 mm; And / or, both the anode plate and the cathode plate have straight flow channels or serpentine flow channels.

4. The composite bipolar plate for producing hydrogen by electrolysis of water according to claim 1, characterized in that: The conductive filler is one or more of flake graphite, spherical graphite, microcrystalline graphite, expanded graphite, and carbon black, and the carbon content of the conductive filler is ≥99.995%.

5. The composite bipolar plate for producing hydrogen by electrolysis of water according to claim 1, characterized in that: The fiber reinforcement material is one or more of chopped carbon fiber, glass fiber, polyetheretherketone fiber, polyphenylene sulfide fiber, polysulfone fiber, and carbon nanotube; The length of the fiber is 0.5-4 mm, the diameter is 5-20 μm, and the fiber surface is oxidized by wet oxidation and / or electro-Fenton oxidation.

6. The composite bipolar plate for producing hydrogen by electrolysis of water according to claim 1, characterized in that: The surfaces of the stirring paddle and the kneading paddle are thermally sprayed with zirconium oxide or Teflon coating, and the coating thickness is 20-200 μm and the roughness is ≤0.05 μm.

7. Use of the composite bipolar plate according to any one of claims 1 to 5 in hydrogen production by water electrolysis.

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