Bipolar plate of proton exchange membrane electrolytic cell, and preparation method therefor

Abstract

The present invention provides a bipolar plate of a proton exchange membrane electrolytic cell, and a preparation method therefor. The bipolar plate of a proton exchange membrane electrolytic cell comprises a base material layer and a coating which are laminated; the base material layer is made of metal titanium or titanium alloy; and the coating is a single metal layer or an alloy layer, the metal in the single metal layer is amorphous, and the metal in the alloy layer is amorphous. Compared with conventional bipolar plates with precious metal coatings, the bipolar plate of a proton exchange membrane electrolytic cell provided by the present application achieves a low material cost. Additionally, the metal in the single metal layer and the metal in the alloy layer are both amorphous, the crystallinity is low, and compared with bipolar plates comprising amorphous metals, the bipolar plate of a proton exchange membrane electrolytic cell provided by the present application has excellent conductivity and low surface resistance, and also has better oxidation resistance and corrosion resistance.

Description

Proton exchange membrane electrolyzer bipolar plate and preparation method thereof

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on June 26, 2023, with application number 202310771442.5 and invention name “Proton Exchange Membrane Electrolyzer Bipolar Plate and Preparation Method Thereof”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates to the technical field of surface chemical treatment, and in particular to a bipolar plate for a proton exchange membrane electrolyzer and a preparation method thereof. Background Art

[0003] As a key component in a proton exchange membrane electrolyzer, bipolar plates are primarily used to separate the individual electrolytic cells, conduct heat and current between them, and distribute reactants within the cell. Because bipolar plates operate in an acidic environment with high anodic potential, they must exhibit high electrochemical corrosion resistance, high mechanical strength, high shock resistance, and ease of mass production. Surface modification of the substrate is often performed to improve conductivity, oxidation resistance, and electrochemical corrosion resistance.

[0004] Currently, the coatings used in bipolar plates of proton exchange membrane electrolyzers are produced using methods such as magnetron sputtering, ionic liquid deposition, chemical vapor deposition, and molten salt deposition. These processes heat the substrate, affecting coating performance. Furthermore, the cost of electroplating the platinum layer on the substrate is high.

[0005] To reduce costs, researchers have used other transition metal elements or alloys as coating materials. For example, Chinese patent application CN114214658A discloses a composite coating for metal bipolar plates for water electrolysis. The composite coating includes a self-healing layer and a corrosion-resistant layer that are alternately arranged along the surface of the metal bipolar plate toward the outside, alternating at least once. The outermost layer is a conductive layer; the self-healing layer is an alloy of one or more of titanium, zirconium, niobium, chromium, and tantalum; the corrosion-resistant layer is a transition metal oxynitride layer, wherein the transition metal oxynitride includes at least one of titanium oxynitride, zirconium oxynitride, and niobium oxynitride, and the atomic ratio of oxygen atoms is between 1% and 20%; the conductive layer is a transition metal nitride layer, wherein the transition metal nitride includes at least one of titanium nitride, zirconium nitride, niobium nitride, chromium nitride, and niobium nitride.

[0006] However, the existing coating process for preparing amorphous coatings requires stringent conditions, and the surface resistivity, oxidation resistance, and electrochemical corrosion resistance of the resulting bipolar plates containing amorphous tantalum coatings need to be improved. Therefore, it is crucial to research and develop a bipolar plate for proton exchange membrane electrolyzers that is simpler to prepare, has low surface resistivity, and exhibits excellent oxidation resistance and electrochemical corrosion resistance.

[0007] Summary of the Invention

[0008] The main purpose of the present invention is to provide a proton exchange membrane electrolyzer bipolar plate and its preparation method to solve the problems in the prior art of proton exchange membrane electrolyzer bipolar plates, such as the complex preparation process and the difficulty of the prepared proton exchange membrane electrolyzer bipolar plate to achieve low surface resistivity, good oxidation resistance, and good electrochemical corrosion resistance.

[0009] In order to achieve the above-mentioned objectives, the present invention provides, on the one hand, a bipolar plate for a proton exchange membrane electrolyzer, which comprises a substrate layer and a coating layer arranged in a stacked manner; the material of the substrate layer is metallic titanium or a titanium alloy; the coating layer is a single metal layer or an alloy layer, the metal in the single metal layer is amorphous, and the metal in the alloy layer is amorphous.

[0010] Furthermore, the metal in the single metal layer is selected from one of the elements in Group IVB, Group VB, and Group VIB; the alloy in the alloy layer is selected from an alloy consisting of two or more of the elements in Group IVB, Group VB, and Group VIB.

[0011] Furthermore, the titanium alloy is selected from titanium-palladium alloy, titanium-aluminum alloy or titanium-aluminum-vanadium alloy; the metal in the single metal layer is selected from one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten; the alloy in the alloy layer is selected from an alloy composed of two or more of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten; preferably, the coating is a titanium coating, a tantalum coating, a niobium coating, a tantalum-niobium alloy coating, a tantalum-hafnium alloy coating, a titanium-tantalum alloy coating, a titanium-niobium alloy coating or a titanium-chromium alloy coating; preferably, when the material of the substrate layer is metallic titanium, the coating is selected from a tantalum coating, a niobium coating, a titanium coating, a tantalum-niobium alloy coating, a titanium-tantalum alloy coating, a titanium-niobium alloy coating or a tantalum-hafnium alloy coating.

[0012] Furthermore, the thickness of the coating is 0.01 to 10 μm, preferably 0.02 to 5 μm.

[0013] Furthermore, the thickness of the substrate layer is 0.5 to 5 mm.

[0014] In order to achieve the above-mentioned purpose, another aspect of the present invention further provides a method for preparing the above-mentioned proton exchange membrane electrolyzer bipolar plate provided in this application, and the preparation method includes: step S1, preparing a substrate; step S2, preparing a coating on the surface of the substrate, and cooling the substrate during the coating preparation process so that the temperature of the substrate is ≤50°C, thereby obtaining a proton exchange membrane electrolyzer bipolar plate.

[0015] Furthermore, the coating is prepared by magnetron sputtering or multi-arc ion plating.

[0016] Furthermore, the coating preparation process is carried out in a magnetron sputtering ion composite coating device and uses a target material as an evaporation source, which includes the following steps: using a coolant to maintain the temperature of the substrate at 10 to 50°C, turning on the deposition target current, and making the working gas pressure 4.0×10 -4 ~9.0×10 -4 torr, a bias voltage of -50 to -800 V, a current of 0.3 to 100 A, and a treatment time of 3 to 300 min to obtain a bipolar plate for a proton exchange membrane electrolyzer; preferably, the evaporation source is selected from one or more of the group consisting of metal titanium, metal zirconium, metal hafnium, metal vanadium, metal niobium, metal tantalum, metal chromium, metal molybdenum, and metal tungsten, or a niobium-tantalum alloy, a tantalum-hafnium alloy, a titanium-tantalum alloy, a titanium-niobium alloy, or a titanium-chromium alloy; and / or the coolant is selected from one or more of the group consisting of water, ethylene glycol, ethanol, and freon.

[0017] Furthermore, step S1 also includes a pretreatment process, including: immersing the substrate to be treated in an acidic solution to remove the oxide film on the surface of the substrate to be treated; after polishing, ultrasonic cleaning and drying, transferring it to a magnetron sputtering ion composite coating equipment for ion bombardment cleaning to obtain a substrate; preferably, the acidic solution is selected from oxalic acid solution, hydrochloric acid solution or sulfuric acid solution; preferably, the mass concentration is 1 to 20wt% oxalic acid, the mass concentration is 5 to 35wt% hydrochloric acid or the mass concentration is 2 to 30wt% sulfuric acid; preferably, the temperature of the immersion process is 40 to 80°C and the time is 3 to 20min; preferably, after the polishing process, a substrate with a surface roughness of Ra 0.01 to Ra 0.1 is obtained.

[0018] Furthermore, the ion bombardment cleaning process includes: turning on the deposition target current to make the vacuum degree of the furnace chamber ≤3.0×10 -5 torr, the substrate bias voltage is -300 to -700 V, the deposition current is 2 to 80 A, and the substrate is obtained after processing for 5 to 60 minutes.

[0019] By applying the technical solution of the present invention, the material cost of the proton exchange membrane electrolyzer bipolar plate provided by the present application is low compared with traditional bipolar plates with precious metal coatings; moreover, the metals in the above-mentioned single metal layer and alloy layer are all amorphous (that is, the metal atoms in the layer are arranged disorderly in three-dimensional space, rather than arranged periodically according to a certain rule) and have low crystallinity. Compared with crystalline metals, the above-mentioned proton exchange membrane electrolyzer bipolar plate provided by the present application has better oxidation resistance and corrosion resistance while having excellent conductivity and low surface resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0021] FIG1 shows a SEM image of the surface of the amorphous tantalum coating prepared in Example 1 of the present invention;

[0022] FIG2 shows a SEM image of the surface of the amorphous niobium coating prepared in Example 7 of the present invention;

[0023] FIG3 shows a curve showing the change in surface resistivity of bipolar plates prepared in Example 1 of the present invention and Comparative Examples 1 and 2 as a function of pressure;

[0024] FIG4 shows the electrolysis performance curves of the bipolar plates prepared in Example 1 and Comparative Examples 1 and 2 of the present invention (tested at 60° C.). DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] As described in the background art, existing proton exchange membrane electrolyzer bipolar plates have complex preparation processes, and the resulting proton exchange membrane electrolyzer bipolar plates are difficult to achieve simultaneously low surface resistivity, good oxidation resistance, and good electrochemical corrosion resistance. In order to solve the above technical problems, the present application provides a proton exchange membrane electrolyzer bipolar plate, which includes a laminated substrate layer and a coating; the substrate layer is made of titanium or a titanium alloy; the coating is a single metal layer or an alloy layer, the metal in the single metal layer is amorphous, and the metal in the alloy layer is amorphous.

[0027] Compared with traditional bipolar plates with precious metal coatings, the material cost of the above-mentioned proton exchange membrane electrolyzer bipolar plate provided in the present application is low; moreover, the metals in the above-mentioned single metal layer and alloy layer are all amorphous (that is, the metal atoms in the layer are arranged disorderly in three-dimensional space, rather than arranged periodically according to a certain rule) and have low crystallinity. Compared with crystalline metals, the above-mentioned proton exchange membrane electrolyzer bipolar plate provided in the present application has better oxidation resistance and corrosion resistance while having excellent conductivity and lower surface resistance.

[0028] In a preferred embodiment, the metal in the single metal layer includes, but is not limited to, one element from Group IVB, Group VB, and Group VIB; the alloy in the alloy layer includes, but is not limited to, an alloy composed of two or more elements from Group IVB, Group VB, and Group VIB. The types of the metal in the single metal layer and the alloy in the alloy layer independently include, but are not limited to, the aforementioned ranges. Limiting these to within the aforementioned ranges is beneficial for improving the conductivity, oxidation resistance, and electrochemical corrosion resistance of the bipolar plates in proton exchange membrane electrolyzers.

[0029] In a preferred embodiment, titanium alloys include, but are not limited to, titanium-palladium alloys, titanium-aluminum alloys, or titanium-aluminum-vanadium alloys. Compared to pure titanium, the use of these preferred titanium alloys improves the electrochemical corrosion resistance of the bipolar plates in proton exchange membrane electrolyzers, facilitates bipolar plate processing and molding, and improves overall performance, such as lightweighting of the electrolyzer.

[0030] In a preferred embodiment, the metal in the single metal layer includes, but is not limited to, one of titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), and tungsten (W); the alloy in the alloy layer includes, but is not limited to, an alloy of two or more of zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten. The metal in the single metal layer and the alloy in the alloy layer each independently include, but are not limited to, the aforementioned ranges. Limiting them to the aforementioned ranges is beneficial for further improving the conductivity, oxidation resistance, and electrochemical corrosion resistance of the bipolar plate of the proton exchange membrane electrolyzer.

[0031] In order to further improve the conductivity of the bipolar plate of the proton exchange membrane electrolyzer and further improve the oxidation resistance and electrochemical corrosion resistance of the bipolar plate, preferably, the coating is a titanium coating, a tantalum coating, a niobium coating, a tantalum-niobium alloy (Ta-Nb alloy) coating, a tantalum-hafnium alloy (Ta-Hf alloy) coating, a titanium-tantalum alloy coating, a titanium-niobium alloy coating or a titanium-chromium alloy coating.

[0032] In a preferred embodiment, when the substrate layer is made of metallic titanium, the coating includes, but is not limited to, tantalum coatings, niobium coatings, titanium coatings, tantalum-niobium alloy coatings, titanium-tantalum alloy coatings, titanium-niobium alloy coatings, or tantalum-hafnium alloy coatings. Compared to other types, substrate layers and coatings composed of the aforementioned materials further enhance the high corrosion resistance of the substrate and coating, thereby further improving the oxidation resistance and electrochemical corrosion resistance of the bipolar plates in proton exchange membrane electrolyzers.

[0033] In a preferred embodiment, the coating has a thickness of 0.01 to 10 μm. The coating thickness includes, but is not limited to, the aforementioned range. Limiting the coating thickness within the aforementioned range is beneficial for effectively forming a protective coating on the surface of the proton exchange membrane electrolyzer bipolar plate, completely covering the substrate layer and effectively protecting the substrate layer. Furthermore, it is beneficial for improving the conductivity of the proton exchange membrane electrolyzer bipolar plate, and for enhancing its overall performance, such as oxidation resistance and electrochemical corrosion resistance.

[0034] In order to further improve the comprehensive performance of the bipolar plate of the proton exchange membrane electrolyzer, such as conductivity, oxidation resistance and electrochemical corrosion resistance, the preferred thickness is 0.02 to 5 μm.

[0035] In a preferred embodiment, the thickness of the substrate layer is 0.5 to 5 mm. The thickness of the substrate layer includes, but is not limited to, the aforementioned range. Limiting the thickness of the substrate layer within the aforementioned range is beneficial for further improving the overall performance of the bipolar plates of the proton exchange membrane electrolyzer, including electrical conductivity, oxidation resistance, and electrochemical corrosion resistance.

[0036] The second aspect of the present application also provides a method for preparing the above-mentioned proton exchange membrane electrolyzer bipolar plate provided by the present application, and the preparation method includes: step S1, preparing a substrate; step S2, preparing a coating on the surface of the substrate, and cooling the substrate during the coating preparation process so that the temperature of the substrate is ≤50°C, thereby obtaining a proton exchange membrane electrolyzer bipolar plate.

[0037] A coating is prepared on the surface of a substrate, and the substrate is cooled during the coating preparation process to keep the substrate temperature ≤50°C. This can make the metal in the resulting coating amorphous (i.e., the metal atoms in the layer are arranged disorderly in three-dimensional space, rather than arranged periodically according to a certain rule), thereby suppressing the effect of excessive substrate temperature on the coating performance. Moreover, the single metal layer or alloy layer composed of the metal in the single metal layer or the alloy in the alloy layer prepared by the above method has low crystallinity, which can improve the corrosion resistance and oxidation resistance of the coating, thereby reducing the surface resistivity of the bipolar plate of the proton exchange membrane electrolyzer, improving its conductivity, and at the same time improving its oxidation resistance and electrochemical corrosion resistance.

[0038] In a preferred embodiment, the coating is prepared by magnetron sputtering or multi-arc ion plating.

[0039] The magnetron sputtering process involves incident ions exchanging energy and momentum through a series of collisions. During this process, electrons, accelerated by an electric field, collide with argon atoms as they fly toward the substrate, ionizing a large number of argon ions and electrons. Electrons fly toward the substrate, continuously colliding with argon atoms as they fly toward the substrate, generating more argon ions and electrons. The argon ions, accelerated by the electric field, bombard the target material, sputtering a large number of target atoms. These neutral target atoms or molecules are then deposited on the substrate surface, forming a coating.

[0040] The multi-arc ion plating process utilizes arc discharge principles to ionize the target surface, generating a large number of metal ions and a small molten pool. The positive ionization zone near the target surface promotes the sputtering of the molten material in the small molten pool, producing large droplets. The metal ions travel at high speed to the substrate surface and participate in coating deposition. The large droplets are adsorbed on the substrate due to reverse sputtering, forming a coating.

[0041] In a preferred embodiment, the process of preparing the coating is carried out in a magnetron sputtering ion composite coating device and uses a target material as an evaporation source, which includes the following steps: using a coolant to maintain the temperature of the substrate at 10 to 50°C, turning on the deposition target current, and making the working gas pressure 4.0×10 -4 ~9.0×10 -4 The bipolar plates are obtained after a treatment time of 3 to 300 minutes at a bias voltage of -50 to -800 V and a current of 0.3 to 100 A. Compared with other conditions, the above process conditions are beneficial for reducing the degree of crystallization of the coating, improving the corrosion resistance and oxidation resistance of the coating, and thus improving the corrosion resistance and oxidation resistance of the bipolar plates in the proton exchange membrane electrolyzer, thereby achieving better performance under electrolysis conditions.

[0042] In a preferred embodiment, the evaporation source includes, but is not limited to, one or more of the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten, or a niobium-tantalum alloy, a tantalum-hafnium alloy, a titanium-tantalum alloy, a titanium-niobium alloy, or a titanium-chromium alloy. The evaporation source includes, but is not limited to, the aforementioned types. Limiting it to the aforementioned range is beneficial for improving the corrosion resistance, stability, and oxidation resistance of the coating, improving the conductivity of the bipolar plates of the proton exchange membrane electrolyzer, and enhancing their oxidation resistance and electrochemical corrosion resistance.

[0043] In a preferred embodiment, the coolant includes, but is not limited to, one or more of the group consisting of water, ethylene glycol, ethanol, and Freon. Compared to other types, these coolants have high cooling efficiency and low cost, which helps improve cooling efficiency and further reduce the degree of crystallization of the coating.

[0044] In a preferred embodiment, when the evaporation source is a sputtered tantalum metal target, the magnetron sputtering bias voltage is -600 to -800 V, and the current is 2 to 7 A. When the evaporation source is a multi-arc tantalum metal target, the multi-arc bias voltage is -80 to -150 V, and the current is 70 to 150 A. For specific types of evaporation sources, the use of these process conditions can further reduce the degree of crystallization of the coating, thereby improving the corrosion resistance and oxidation resistance of the bipolar plates in proton exchange membrane electrolyzers, thereby achieving better performance under electrolysis conditions.

[0045] In a preferred embodiment, when the evaporation source is a sputtered tantalum metal target, the magnetron sputtering bias voltage is -600 to -700 V, and the current is 3 to 5 A. When the evaporation source is a multi-arc tantalum metal target, the multi-arc bias voltage is -80 to -100 V, and the current is 80 to 100 A. For specific types of evaporation sources, the use of these process conditions can further reduce the degree of crystallization of the coating, thereby improving the corrosion resistance and oxidation resistance of the bipolar plates in proton exchange membrane electrolyzers, thereby achieving better performance under electrolysis conditions.

[0046] In a preferred embodiment, when the evaporation source is a sputtered niobium target, the magnetron sputtering bias voltage is -550 to -700 V, and the current is 2 to 7 A. When the evaporation source is a multi-arc niobium target, the multi-arc bias voltage is -70 to -120 V, and the current is 60 to 150 A. For specific types of evaporation sources, employing these process conditions can further reduce the degree of crystallization of the coating, thereby improving the corrosion resistance and oxidation resistance of the bipolar plates in proton exchange membrane electrolyzers, resulting in better performance under electrolysis conditions.

[0047] In a preferred embodiment, when the evaporation source is a sputtered niobium target, the magnetron sputtering bias voltage is -600 to -650 V, and the current is 3 to 5 A. When the evaporation source is a multi-arc niobium target, the multi-arc bias voltage is -70 to -90 V, and the current is 80 to 90 A. For specific types of evaporation sources, employing these process conditions can further reduce the degree of crystallization of the coating, thereby improving the corrosion resistance and oxidation resistance of the bipolar plates in proton exchange membrane electrolyzers, resulting in better performance under electrolysis conditions.

[0048] In a preferred embodiment, when the evaporation source is a sputtered titanium target, the magnetron sputtering bias voltage is -500 to -700 V, and the current is 2 to 7 A. When the evaporation source is a multi-arc titanium target, the multi-arc bias voltage is -60 to -100 V, and the current is 60 to 120 A. For specific types of evaporation sources, the use of these process conditions can further reduce the degree of crystallization of the coating, thereby improving the corrosion resistance and oxidation resistance of the bipolar plates in proton exchange membrane electrolyzers, thereby achieving better performance under electrolysis conditions.

[0049] In a preferred embodiment, when the evaporation source is a sputtered titanium target, the magnetron sputtering bias voltage is -550 to -600 V, and the current is 3 to 5 A. When the evaporation source is a multi-arc titanium target, the multi-arc bias voltage is -70 to -80 V, and the current is 80 to 90 A. For specific types of evaporation sources, the use of these process conditions can further reduce the degree of crystallization of the coating, thereby improving the corrosion resistance and oxidation resistance of the bipolar plates in proton exchange membrane electrolyzers, resulting in better performance under electrolysis conditions.

[0050] In a preferred embodiment, when the evaporation source is a sputtered tantalum-niobium alloy target, or a sputtered tantalum target and a sputtered niobium target, the magnetron sputtering bias voltage is -600 to -800 V, and the current is 2 to 7 A. When the evaporation source is a multi-arc tantalum-niobium alloy target, or a multi-arc tantalum target and a multi-arc niobium target, the multi-arc bias voltage is -80 to -150 V, and the current is 70 to 150 A. For specific types of evaporation sources, employing these process conditions can further reduce the degree of crystallization of the coating, thereby improving the corrosion resistance and oxidation resistance of the bipolar plates in proton exchange membrane electrolyzers, resulting in better performance under electrolysis conditions.

[0051] In a preferred embodiment, when the evaporation source is a sputtered tantalum-niobium alloy target, or a sputtered tantalum target and a sputtered niobium target, the magnetron sputtering bias voltage is -650 to -800 V, and the current is 3 to 5 A. When the evaporation source is a multi-arc tantalum-niobium alloy target, or a multi-arc tantalum target and a multi-arc niobium target, the multi-arc bias voltage is -80 to -100 V, and the current is 80 to 100 A. For specific evaporation sources, employing these process conditions can further reduce the degree of crystallization of the coating, thereby improving the corrosion resistance and oxidation resistance of the bipolar plates in proton exchange membrane electrolyzers, resulting in better performance under electrolysis conditions.

[0052] In a preferred embodiment, when the evaporation source is a sputtered titanium-tantalum alloy target, or a sputtered titanium target and a sputtered tantalum target, the magnetron sputtering bias voltage is -600 to -800 V, and the current is 2 to 7 A. When the evaporation source is a multi-arc titanium-tantalum alloy target, or a multi-arc titanium target and a multi-arc tantalum target, the multi-arc bias voltage is -80 to -150 V, and the current is 70 to 150 A. For specific types of evaporation sources, the use of the above process conditions is beneficial for further reducing the degree of crystallization of the coating, thereby improving the corrosion resistance and oxidation resistance of the bipolar plates of the proton exchange membrane electrolyzer, thereby achieving better performance under electrolysis conditions.

[0053] In a preferred embodiment, when the evaporation source is a sputtered titanium-tantalum alloy target, or a sputtered titanium target and a sputtered tantalum target, the magnetron sputtering bias voltage is -650 to -800 V, and the current is 3 to 5 A. When the evaporation source is a multi-arc titanium-tantalum alloy target, or a multi-arc titanium target and a multi-arc tantalum target, the multi-arc bias voltage is -80 to -100 V, and the current is 80 to 100 A. For specific types of evaporation sources, the use of the above process conditions is beneficial for further reducing the degree of crystallization of the coating, thereby improving the corrosion resistance and oxidation resistance of the bipolar plates of the proton exchange membrane electrolyzer, thereby achieving better performance under electrolysis conditions.

[0054] In a preferred embodiment, when the evaporation source is a sputtered titanium-niobium alloy target, or a sputtered titanium target and a sputtered niobium target, the magnetron sputtering bias voltage is -550 to -700 V, and the current is 2 to 7 A. When the evaporation source is a multi-arc titanium-niobium alloy target, or a multi-arc titanium target and a multi-arc niobium target, the multi-arc bias voltage is -70 to -120 V, and the current is 60 to 150 A. For specific types of evaporation sources, the use of these process conditions can further reduce the degree of crystallization of the coating, thereby improving the corrosion resistance and oxidation resistance of the bipolar plates of proton exchange membrane electrolyzers, thereby achieving better performance under electrolysis conditions.

[0055] In a preferred embodiment, when the evaporation source is a sputtered titanium-niobium alloy target, or a sputtered titanium metal target and a sputtered niobium metal target, the magnetron sputtering bias voltage is -600 to -700 V, and the current is 3 to 6 A. When the evaporation source is a multi-arc titanium-niobium alloy target, or a multi-arc titanium metal target and a multi-arc niobium metal target, the multi-arc bias voltage is -70 to -100 V, and the current is 80 to 100 A. For specific types of evaporation sources, the use of these process conditions can further reduce the degree of crystallization of the coating, thereby improving the corrosion resistance and oxidation resistance of the bipolar plates of the proton exchange membrane electrolyzer, thereby achieving better performance under electrolysis conditions.

[0056] In a preferred embodiment, step S1 also includes a pretreatment process, including: immersing the substrate to be treated in an acidic solution to remove the oxide film on the surface of the substrate to be treated; after polishing, ultrasonic cleaning, and drying, transferring the substrate to a magnetron sputtering ion composite coating device for ion bombardment cleaning to obtain the substrate. This treatment of the substrate to be treated is beneficial for removing the oxide film on its surface and inhibiting the effect of the oxide film on the conductivity of the bipolar plates of the proton exchange membrane electrolyzer, thereby improving the conductivity of the subsequently produced bipolar plates of the proton exchange membrane electrolyzer and reducing their surface resistivity.

[0057] The acidic solution used in this application can be a common type in the art. In a preferred embodiment, the acidic solution includes but is not limited to oxalic acid solution, hydrochloric acid solution or sulfuric acid solution.

[0058] In order to improve the removal effect of the oxide film, preferably, the acidic solution includes but is not limited to oxalic acid with a mass concentration of 1 to 20 wt%, hydrochloric acid with a mass concentration of 5 to 35 wt%, or sulfuric acid with a mass concentration of 2 to 30 wt%.

[0059] In a preferred embodiment, the immersion process temperature is 40-80°C, and the immersion time is 3-20 minutes. The immersion temperature and time include, but are not limited to, the above-mentioned ranges. Limiting them to the above-mentioned ranges is beneficial to the removal efficiency of the oxide film on the surface of the substrate to be treated, and inhibiting the effect of the oxide film on the conductivity of the bipolar plate of the proton exchange membrane electrolyzer, thereby facilitating the improvement of the conductivity of the subsequently produced bipolar plate of the proton exchange membrane electrolyzer and reducing its surface resistivity.

[0060] In order to improve the machinability of the substrate and thus enhance the adhesion between the coating and the substrate, preferably, the substrate has a surface roughness of Ra 0.01 to Ra 0.1 after the grinding process.

[0061] In a preferred embodiment, the ion bombardment cleaning process includes: turning on the deposition target current to make the vacuum degree of the furnace chamber ≤3.0×10 -5 torr, substrate bias voltage is -300 to -700 V, deposition current is 2 to 80 A, and treatment time is 5 to 60 min to obtain a substrate. The above process conditions are used for ion bombardment cleaning, which is beneficial to further improve the removal rate of the oxide film.

[0062] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0063] Example 1

[0064] A method for preparing a bipolar plate for a proton exchange membrane electrolyzer, comprising:

[0065] (1) A TA1 pure titanium substrate was immersed in a 10 wt% oxalic acid solution to remove the surface oxide film. The immersion temperature was 70°C for 15 min. The substrate was mechanically polished to a surface roughness of Ra 0.01, ultrasonically cleaned with deionized water and acetone, and then dried in a 60°C oven. The substrate was then mounted on a rotating sample holder in the furnace chamber of a magnetron sputtering ion composite coating device. The substrate was vacuumed to 3.0×10 -5 torr, argon gas was introduced, the bias voltage was increased to -500 V, and the ion bombardment cleaning process was started. After 20 min of treatment, the substrate was obtained;

[0066] (2) Turn on the chiller and maintain the substrate temperature at 30°C through the coolant; adjust the substrate bias (magnetron sputtering bias) to -700 V, use the sputtering tantalum target as the evaporation source, the tantalum target current is 3 A, and deposit the coating on the surface of the above substrate for 70 minutes; after the deposition is completed, cool down to obtain the bipolar plate of the proton exchange membrane electrolyzer.

[0067] As shown in Figure 1, the amorphous tantalum coating evenly covers the substrate surface, leaving no exposed substrate. The bipolar plate produced in Example 1 includes a stacked titanium substrate layer and an amorphous tantalum (Ta) coating. The substrate layer is 0.5 mm thick, and the amorphous tantalum coating is 0.5 μm thick.

[0068] Example 2

[0069] The preparation process of the substrate is the same as step (1) in Example 1.

[0070] The difference from Example 1 is that in step (2), the substrate bias voltage is -600 V, the tantalum target current is 5 A, and the deposition time is 60 min.

[0071] The bipolar plate prepared in Example 2 includes a titanium substrate layer and an amorphous tantalum (Ta) coating layer that are stacked, wherein the substrate layer has a thickness of 0.5 mm and the amorphous tantalum coating has a thickness of 0.5 μm.

[0072] Example 3

[0073] The preparation process of the substrate is the same as step (1) in Example 1.

[0074] The difference from Example 1 is that in step (2), the evaporation source is a multi-arc tantalum target, the substrate bias (multi-arc bias) is -100 V, the tantalum target current is 80 A, and the deposition time is 30 min.

[0075] The bipolar plate prepared in Example 3 includes a titanium substrate layer and an amorphous tantalum (Ta) coating layer stacked together, wherein the substrate layer has a thickness of 0.5 mm and the amorphous tantalum coating has a thickness of 0.5 μm.

[0076] Example 4

[0077] The preparation process of the substrate is the same as step (1) in Example 1.

[0078] The difference from Example 3 is that in step (2), the tantalum target current is 100 A and the deposition time is 30 min.

[0079] The bipolar plate prepared in Example 4 includes a titanium substrate layer and an amorphous tantalum (Ta) coating layer that are stacked, wherein the substrate layer has a thickness of 0.5 mm and the amorphous tantalum coating has a thickness of 0.6 μm.

[0080] Example 5

[0081] A method for preparing a bipolar plate for a proton exchange membrane electrolyzer, comprising:

[0082] (1) The same as step (1) in Example 1, to obtain a substrate;

[0083] (2) Turn on the chiller and maintain the substrate temperature at 30°C through the coolant; adjust the substrate bias to -650V, use the sputtered niobium target as the evaporation source, and the niobium target current is 3A to deposit a coating on the surface of the substrate for 70 minutes; after the deposition is completed, cool down to obtain a bipolar plate for a proton exchange membrane electrolyzer.

[0084] The bipolar plate prepared in Example 5 includes a titanium substrate layer and an amorphous niobium (Nb) coating layer stacked together, wherein the substrate layer has a thickness of 0.5 mm and the amorphous niobium coating layer has a thickness of 0.5 μm.

[0085] Example 6

[0086] The preparation process of the substrate is the same as step (1) in Example 5.

[0087] The difference from Example 5 is that in step (2), the substrate bias voltage is -600 V, the niobium target current is 5 A, and the deposition time is 60 min.

[0088] The bipolar plate prepared in Example 6 includes a titanium substrate layer and an amorphous niobium (Nb) coating layer that are stacked, wherein the substrate layer has a thickness of 0.5 mm, and the amorphous niobium coating layer has a thickness of 0.5 μm.

[0089] Example 7

[0090] The preparation process of the substrate is the same as step (1) in Example 5.

[0091] The difference from Example 5 is that in step (2), the evaporation source is a multi-arc niobium target, the substrate bias (multi-arc bias) is -70 V, the niobium target current is 100 A, and the deposition time is 30 min.

[0092] As shown in Figure 2, the amorphous niobium coating evenly and effectively covers the substrate surface, leaving no exposed substrate. The bipolar plate produced in Example 7 includes a stacked titanium substrate layer and an amorphous niobium (Nb) coating. The substrate layer is 0.5 mm thick, and the amorphous niobium coating is 0.5 μm thick.

[0093] Example 8

[0094] The preparation process of the substrate is the same as step (1) in Example 5.

[0095] The difference from Example 5 is that in step (2), the evaporation source is a multi-arc niobium target, the substrate bias is -90 V, the niobium target current is 80 A, and the deposition time is 30 min.

[0096] The bipolar plate prepared in Example 8 includes a stacked titanium substrate layer and an amorphous niobium (Nb) coating layer, wherein the substrate layer has a thickness of 0.5 mm and the amorphous niobium coating layer has a thickness of 0.5 μm.

[0097] Example 9

[0098] A method for preparing a bipolar plate for a proton exchange membrane electrolyzer, comprising:

[0099] (1) The same as step (1) in Example 1, to obtain a substrate;

[0100] (2) Turn on the chiller and maintain the substrate temperature at 30°C through the coolant; adjust the substrate bias to -600V, use the sputtered titanium target as the evaporation source, the titanium target current is 3A, and deposit a coating on the surface of the above substrate for 70 minutes; after the deposition is completed, cool down to obtain a proton exchange membrane electrolyzer bipolar plate.

[0101] The bipolar plate prepared in Example 9 includes a titanium substrate layer and an amorphous titanium (Ti) coating layer that are stacked together, wherein the substrate layer has a thickness of 0.5 mm and the amorphous titanium coating layer has a thickness of 0.5 μm.

[0102] Example 10

[0103] The preparation process of the substrate is the same as step (1) in Example 9.

[0104] The difference from Example 9 is that in step (2), the substrate bias is -550 V, the titanium target current is 5 A, and the deposition time is 60 min.

[0105] The bipolar plate prepared in Example 10 includes a stacked titanium substrate layer and an amorphous titanium (Ti) coating layer, wherein the substrate layer has a thickness of 0.5 mm and the amorphous titanium coating layer has a thickness of 0.5 μm.

[0106] Example 11

[0107] The preparation process of the substrate is the same as step (1) in Example 9.

[0108] The difference from Example 9 is that in step (2), the evaporation source is a multi-arc titanium target, the substrate bias (multi-arc bias) is -70 V, the titanium target current is 90 A, and the deposition time is 30 min.

[0109] The bipolar plate prepared in Example 11 includes a titanium substrate layer and an amorphous titanium (Ti) coating layer that are stacked together, wherein the substrate layer has a thickness of 0.5 mm and the amorphous titanium coating layer has a thickness of 0.5 μm.

[0110] Example 12

[0111] The preparation process of the substrate is the same as step (1) in Example 9.

[0112] The difference from Example 9 is that in step (2), the evaporation source is a multi-arc titanium target, the substrate bias (multi-arc bias) is -80 V, the titanium target current is 80 A, and the deposition time is 30 min.

[0113] The bipolar plate prepared in Example 12 includes a titanium substrate layer and an amorphous titanium (Ti) coating layer that are stacked together, wherein the substrate layer has a thickness of 0.5 mm and the amorphous titanium coating layer has a thickness of 0.5 μm.

[0114] Example 13

[0115] A method for preparing a bipolar plate for a proton exchange membrane electrolyzer, comprising:

[0116] (1) The same as step (1) in Example 1, to obtain a substrate;

[0117] (2) Turn on the chiller and maintain the substrate temperature at 30°C through the coolant; adjust the substrate bias (multi-arc bias) to -100V, use the multi-arc tantalum target and niobium target as evaporation sources, the current is 80A, and deposit the coating on the surface of the above substrate for 30 minutes; after the deposition is completed, cool down to obtain the bipolar plate of the proton exchange membrane electrolyzer.

[0118] The bipolar plate prepared in Example 13 includes a stacked titanium substrate layer and an amorphous tantalum-niobium alloy (Ta-Nb alloy) coating, wherein the substrate layer has a thickness of 0.5 mm and the amorphous tantalum-niobium alloy coating has a thickness of 1 μm.

[0119] Example 14

[0120] The preparation process of the substrate is the same as step (1) in Example 13.

[0121] The difference from Example 13 is that in step (2), the evaporation source is a sputtered tantalum target and a niobium target, the substrate bias is -650 V, the current is 3 A, and the deposition time is 60 min.

[0122] The bipolar plate prepared in Example 14 includes a stacked titanium substrate layer and an amorphous tantalum-niobium alloy (Ta-Nb alloy) coating, wherein the substrate layer has a thickness of 0.5 mm and the amorphous tantalum-niobium alloy coating has a thickness of 0.5 μm.

[0123] Example 15

[0124] The preparation process of the substrate is the same as step (1) in Example 13.

[0125] The difference from Example 13 is that in step (2), the evaporation source is a multi-arc tantalum target and a niobium target, the substrate bias is -80 V, the current is 90 A, and the deposition time is 30 min.

[0126] The bipolar plate prepared in Example 15 includes a stacked titanium substrate layer and an amorphous tantalum-niobium alloy (Ta-Nb alloy) coating, wherein the substrate layer has a thickness of 0.5 mm and the amorphous tantalum-niobium alloy coating has a thickness of 0.5 μm.

[0127] Example 16

[0128] The preparation process of the substrate is the same as step (1) in Example 13.

[0129] The difference from Example 13 is that in step (2), the evaporation source is a sputtered titanium-niobium alloy target with an atomic ratio of 1:1, the substrate bias is -600 V, the current is 6 A, and the deposition time is 60 min.

[0130] The bipolar plate prepared in Example 16 includes a stacked titanium substrate layer and an amorphous titanium-niobium alloy (Ti-Nb alloy) coating layer, wherein the substrate layer has a thickness of 0.5 mm and the amorphous titanium-niobium alloy coating layer has a thickness of 1 μm.

[0131] Example 17

[0132] A method for preparing a bipolar plate for a proton exchange membrane electrolyzer, comprising:

[0133] (1) The same as step (1) in Example 1, to obtain a substrate;

[0134] (2) Turn on the chiller and maintain the substrate temperature at 30°C through the coolant; adjust the substrate bias to -650V, use a sputtered titanium-tantalum alloy target with an atomic ratio of 1:1 as the evaporation source, and deposit a coating on the surface of the substrate at a current of 5A for 60 minutes; after the deposition is completed, cool down to obtain a bipolar plate for a proton exchange membrane electrolyzer.

[0135] The bipolar plate prepared in Example 17 includes a stacked titanium substrate layer and an amorphous titanium-tantalum alloy (Ti-Ta alloy) coating, wherein the substrate layer has a thickness of 0.5 mm and the amorphous titanium-tantalum alloy coating has a thickness of 0.5 μm.

[0136] Example 18

[0137] The preparation process of the substrate is the same as step (1) in Example 1.

[0138] The difference from Example 1 is that in step (2), the substrate bias voltage is -500 V, the tantalum target current is 1 A, and the deposition time is 30 min.

[0139] In the bipolar plate prepared in this embodiment, the tantalum coating layer does not completely cover the titanium substrate layer, and a portion of the titanium substrate layer is exposed.

[0140] Example 19

[0141] The preparation process of the substrate is the same as step (1) in Example 13.

[0142] The difference from Example 13 is that in step (2), the substrate bias is -200 V, the tantalum target current is 150 A, and the deposition time is 30 min.

[0143] The tantalum-niobium alloy coating in the bipolar plate prepared in this embodiment has poor film-forming properties and many surface defects.

[0144] Example 20

[0145] The preparation process of the substrate is the same as step (1) in Example 17.

[0146] The difference from Example 17 is that in step (2), the substrate bias is -900 V, the tantalum target current is 7 A, and the deposition time is 60 min.

[0147] The film-forming property of the titanium-tantalum alloy coating in the bipolar plate prepared in this embodiment is poor, and the coating peels off.

[0148] Comparative Example 1

[0149] The difference from Example 1 is that the platinum coating sample with a thickness of 0.5 μm is prepared by electroplating.

[0150] Comparative Example 2

[0151] The difference from Example 1 is that during the sputtering process in step (2), the chiller is not turned on and the temperature of the substrate is raised to 350° C.; the remaining steps are the same as in Example 1.

[0152] The surface resistivity of the proton exchange membrane electrolyzer bipolar plates prepared in Examples 1 to 17 and Comparative Examples 1 and 2 was tested at 2 MPa. The electrolysis performance was also tested in a PEM electrolyzer at 60°C. The test results are shown in Table 1.

[0153] Table 1

[0154] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0155] Comparing Example 1 with Comparative Example 1, combined with the test curves shown in Figures 3 and 4, it can be seen that compared with traditional bipolar plates with precious metal coatings, the material cost of the above-mentioned proton exchange membrane electrolyzer bipolar plates provided in the present application is low.

[0156] Comparing Example 1 with Comparative Example 2, compared with Example 1, Comparative Example 2 did not cool the substrate during the sputtering process, and the substrate continued to heat up to 350°C, resulting in an increase in the degree of crystallization of the tantalum coating deposited on the surface, and a significant increase in the bonding strength with the base titanium plate. Combined with the test curves shown in Figures 3 and 4, it can be seen that although pure tantalum has better corrosion resistance than pure titanium, its oxidation resistance remains at the original level, so the electrolytic performance is poor. It can be seen that in the above-mentioned proton exchange membrane electrolyzer bipolar plate provided by the present application, the metals in the single metal layer and the alloy layer are amorphous and have low crystallinity. Compared with crystalline metals, the above-mentioned proton exchange membrane electrolyzer bipolar plate provided by the present application has better oxidation resistance and corrosion resistance while having excellent conductivity and lower surface resistance.

[0157] Hafnium itself has excellent corrosion resistance and wear resistance, and alloying it with tantalum can leverage the advantages of both. Comparing Examples 1, 13, and 17, it can be seen that the bipolar plates produced in Examples 13 and 17 have improved wear resistance compared to pure tantalum coatings.

[0158] By comparing Examples 1 to 4 and Example 18, Examples 13 to 15 and Example 19, and Examples 17 and 20, it can be seen that for a specific type of evaporation source, adopting the preferred process conditions of the present application for coating deposition is beneficial to further reduce the degree of crystallization of the coating, thereby improving the corrosion resistance and oxidation resistance of the bipolar plate of the proton exchange membrane electrolyzer, thereby making it exhibit better performance under electrolysis conditions.

[0159] It should be noted that the terms "first," "second," and the like in the specification and claims of this application are used to distinguish similar objects, and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the application described herein can, for example, be implemented in an order other than that described herein.

[0160] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A bipolar plate for a proton exchange membrane electrolyzer, characterized in that: The bipolar plate of the proton exchange membrane electrolyzer includes a substrate layer and a coating layer which are stacked; the material of the substrate layer is metal titanium or a titanium alloy; the coating layer is a single metal layer or an alloy layer, the metal in the single metal layer is amorphous, and the metal in the alloy layer is amorphous.

2. The proton exchange membrane electrolyzer bipolar plate according to claim 1, characterized in that: The metal in the single metal layer is selected from one of the elements in Group IVB, Group VB and Group VIB; the alloy in the alloy layer is selected from an alloy consisting of two or more of the elements in Group IVB, Group VB and Group VIB.

3. The bipolar plate for a proton exchange membrane electrolyzer according to claim 1, characterized in that: The titanium alloy is selected from titanium-palladium alloy, titanium-aluminum alloy or titanium-aluminum-vanadium alloy; the metal in the single metal layer is selected from one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten; the alloy in the alloy layer is selected from an alloy composed of two or more of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten.

4. The bipolar plate for a proton exchange membrane electrolyzer according to claim 1, characterized in that: The coating is a titanium coating, a tantalum coating, a niobium coating, a tantalum-niobium alloy coating, a tantalum-hafnium alloy coating, a titanium-tantalum alloy coating, a titanium-niobium alloy coating or a titanium-chromium alloy coating.

5. The bipolar plate for a proton exchange membrane electrolyzer according to claim 1, characterized in that: When the material of the substrate layer is metallic titanium, the coating is selected from tantalum coating, niobium coating, titanium coating, tantalum-niobium alloy coating, titanium-tantalum alloy coating, titanium-niobium alloy coating or tantalum-hafnium alloy coating.

6. The bipolar plate for a proton exchange membrane electrolyzer according to claim 1, characterized in that: The coating has a thickness of 0.01 to 10 μm.

7. The bipolar plate for a proton exchange membrane electrolyzer according to claim 1, characterized in that: The coating has a thickness of 0.02 to 5 μm.

8. The bipolar plate for a proton exchange membrane electrolyzer according to any one of claims 1 to 7, characterized in that: The thickness of the substrate layer is 0.5 to 5 mm.

9. A method for preparing a bipolar plate for a proton exchange membrane electrolyzer according to any one of claims 1 to 8, characterized in that: The preparation method comprises: Step S1, preparing a substrate; Step S2, preparing a coating on the surface of the substrate, during which the substrate The cooling process is performed so that the temperature of the substrate is ≤50°C.

10. The method for preparing a bipolar plate for a proton exchange membrane electrolyzer according to claim 9, characterized in that: The process of preparing the coating adopts a magnetron sputtering method or a multi-arc ion plating method.

11. The method for preparing a bipolar plate for a proton exchange membrane electrolyzer according to claim 10, characterized in that: The process of preparing the coating is carried out in a magnetron sputtering ion composite coating device and uses a target material as an evaporation source, which includes the following processes: The temperature of the substrate was maintained at 10-50°C by using a coolant, and the deposition target current was turned on to make the working gas pressure 4.0×10 -4 ~9.0×10 -4 torr, the bias voltage is -50 to -800 V, the current is 0.3 to 100 A, and the proton exchange membrane electrolyzer bipolar plate is obtained after treating for 3 to 300 minutes.

12. The method for preparing a bipolar plate for a proton exchange membrane electrolyzer according to claim 11, characterized in that: The evaporation source is selected from one or more of the group consisting of metal titanium, metal zirconium, metal hafnium, metal vanadium, metal niobium, metal tantalum, metal chromium, metal molybdenum, metal tungsten, or niobium-tantalum alloy, tantalum-hafnium alloy, titanium-tantalum alloy, titanium-niobium alloy or titanium-chromium alloy; and / or, the coolant is selected from one or more of the group consisting of water, ethylene glycol, ethanol and freon.

13. The method for preparing a bipolar plate for a proton exchange membrane electrolyzer according to any one of claims 9 to 12, characterized in that: The step S1 also includes a pre-processing process, including: The substrate to be treated is immersed in an acidic solution to remove the oxide film on the surface of the substrate to be treated; after polishing, ultrasonic cleaning and drying, it is transferred to a magnetron sputtering ion composite coating device for ion bombardment cleaning to obtain the substrate.

14. The method for preparing a bipolar plate for a proton exchange membrane electrolyzer according to claim 13, characterized in that: The acidic solution is selected from oxalic acid solution, hydrochloric acid solution or sulfuric acid solution.

15. The method for preparing a bipolar plate for a proton exchange membrane electrolyzer according to claim 13, characterized in that: The acidic solution is selected from oxalic acid with a mass concentration of 1 to 20 wt%, hydrochloric acid with a mass concentration of 5 to 35 wt%, or sulfuric acid with a mass concentration of 2 to 30 wt%.

16. The method for preparing a bipolar plate for a proton exchange membrane electrolyzer according to claim 13, characterized in that: The temperature of the soaking process is 40-80° C. and the time is 3-20 minutes.

17. The method for preparing a bipolar plate for a proton exchange membrane electrolyzer according to claim 13, characterized in that: After the grinding process, a substrate with a surface roughness of Ra 0.01 to Ra 0.1 is obtained.

18. The method for preparing a bipolar plate for a proton exchange membrane electrolyzer according to claim 13, characterized in that: The ion bombardment cleaning process includes: starting the deposition target current to make the furnace chamber vacuum ≤3.0×10 -5 torr, the substrate bias voltage is -300 to -700 V, the deposition current is 2 to 80 A, and the substrate is obtained after processing for 5 to 60 minutes.

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