Nickel mesh electrode for water electrolysis and preparation method thereof

Abstract

The invention discloses a nickel mesh electrode for electrolysis of water and a preparation method thereof. The preparation method comprises the following steps: step S1: sandblasting the nickel mesh to obtain a sandblasted nickel mesh; step S2: cleaning the sandblasted nickel mesh in step S1, and performing infrared preheating treatment to obtain a preheated nickel mesh; step S3: spraying the mixed metal powder or alloy powder onto the preheated nickel mesh in step S2 by plasma spraying to obtain a nickel mesh containing a metal coating; step S4: placing the nickel mesh containing a metal coating in step S3 in an alkaline solution, and introducing nitrogen into the alkaline solution for activation, and after the activation is completed, cleaning and drying to obtain a nickel mesh electrode. In the preparation method of the nickel mesh electrode for electrolysis of water of the present invention, the nickel mesh is subjected to infrared preheating treatment, which can reduce the temperature difference between the mixed metal powder or alloy powder and the nickel mesh, reduce the stress of the nickel mesh, and remove moisture at the same time, thereby improving the bonding strength between the coating and the nickel mesh and the fatigue resistance of the coating.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen production by electrolysis of water, and particularly relates to a nickel mesh electrode for electrolysis of water and a preparation method thereof. Background Art

[0002] Hydrogen is the main research direction. At present, the preparation of hydrogen is mainly based on water electrolysis. There are three main technical routes: alkaline electrolysis (ALK), exchange membrane (PEM) electrolysis and solid oxide (SOEC) electrolysis. Among them, alkaline water electrolysis is the most widely used water electrolysis hydrogen production technology.

[0003] Electrode is a key component in alkaline water electrolysis hydrogen production system, which has a great influence on oxygen evolution rate and oxygen evolution overpotential. The most commonly used electrode in alkaline water electrolysis hydrogen production system is nickel mesh electrode. At present, the preparation method of nickel mesh electrode includes electroplating, chemical plating, plasma spraying, etc. Among them, the method of preparing nickel mesh electrode by plasma spraying has the advantages of stable process, high quality, environmental protection, and fast spraying speed, and is currently the most widely used method. The specific process of preparing nickel mesh electrode by plasma spraying is: after melting the mixed powder containing metal powder and aluminum pore-forming agent, the mixed powder is sprayed onto the nickel mesh by plasma spraying, and then the sprayed nickel mesh is activated by alkali liquid to prepare a porous nickel mesh electrode. For example, in the patent with publication number CN117661018A, the nickel-molybdenum powder wrapped with aluminum yttrium is sprayed onto the pretreated nickel mesh by plasma spraying, and then after activation, a porous nickel electrode is prepared. However, the bonding strength between the coating and the nickel mesh electrode prepared by plasma spraying is not strong enough, so during the use of the nickel mesh electrode, there will be defects such as unstable performance and short service life. Therefore, further improving the bonding strength between the coating and the nickel mesh is an urgent problem to be solved. Summary of the invention

[0004] The purpose of the present invention is to provide a nickel mesh electrode for electrolyzing water and a preparation method thereof, which can effectively improve the bonding strength of the coating in the nickel mesh electrode, extend the service life of the nickel mesh electrode, and improve the performance of the nickel mesh electrode.

[0005] In a first aspect, the present invention provides a method for preparing a nickel mesh electrode for electrolyzing water, using the following technical scheme: A method for preparing a nickel mesh electrode for electrolyzing water comprises the following steps: Step S1: sandblasting the nickel mesh to obtain a sandblasted nickel mesh; Step S2: After cleaning the nickel mesh after sandblasting in step S1, perform infrared preheating treatment to obtain a preheated nickel mesh; Step S3: spraying the mixed metal powder or alloy powder onto the nickel mesh preheated in step S2 by plasma spraying to obtain a nickel mesh containing a metal coating; Step S4: placing the nickel mesh containing the metal coating in step S3 in an alkaline solution, and introducing nitrogen into the alkaline solution for activation. After the activation is completed, washing and drying are performed to obtain a nickel mesh electrode.

[0006] Preferably, in step S1, the sandblasting abrasive is white corundum or brown corundum, the sandblasting pressure is 2.6-4.4 bar, and the sandblasting time is 2-4 min.

[0007] Preferably, in step S2, laser cleaning is used for cleaning; the laser cleaning parameters are: laser pulse frequency is 15-30kHz, power is 385W-620W, scanning movement speed is 10-25mm / s, and incident angle range is 80-90°.

[0008] Preferably, in step S2, the specific steps of the infrared preheating treatment are: using infrared to heat the nickel mesh to 75-185° C. and keep it warm for 1-5 minutes.

[0009] Preferably, in step S3, the mixed metal powder is a mixed powder composed of nickel powder and aluminum powder, and the mass ratio of nickel powder to aluminum powder is (7~9):(1~3); the alloy powder is nickel-aluminum alloy powder; the mass ratio of nickel to aluminum in the nickel-aluminum alloy powder is (70~90):(10~30).

[0010] Preferably, in step S3, the process parameters of the plasma spraying method are: spraying power is 30~55kw; powder feeding pressure is 0.15~0.5MPa; powder feeding amount is 100~250g / min, and the powder feeding gas is nitrogen; plasma spraying gas is argon and hydrogen, argon flow rate is 45~60 L / min, argon pressure is 0.3~0.6MPa, hydrogen flow rate is 5~15 L / min, and hydrogen pressure is 0.3~0.6MPa; spraying to nickel mesh weight gain 240~300g / m 2 .

[0011] Preferably, in step S4, the alkali solution is a sodium hydroxide solution or a potassium hydroxide solution; the specific steps of activation are: placing the nickel mesh electrode in an alkali solution with an initial concentration of 4-6wt%, and performing the initial activation for 1.5-2.5h; then adding solid alkali to the alkali solution, adjusting the alkali solution concentration to 8-12wt%, performing secondary activation for 1.5-2.5h, adding solid alkali to the alkali solution again, adjusting the alkali solution concentration to 14-16wt%, performing tertiary activation for 1.5-2.5h, and then adding solid alkali to the alkali solution, adjusting the alkali solution concentration to 19-21wt%, and continuing activation for 5-9h.

[0012] Preferably, in step S4, the nitrogen introduction rate is 90-240 L / min.

[0013] Preferably, in step S4, when there are multiple nickel meshes containing metal coatings and activation is performed simultaneously, each nickel mesh containing metal coating needs to be placed in the alkaline solution for an interval of 1 to 5 minutes; the activation time is calculated from the first nickel mesh.

[0014] In a second aspect, the present invention provides a nickel mesh electrode for electrolyzing water, which is prepared by the aforementioned preparation method.

[0015] The above one or more technical solutions of the present invention can achieve at least one of the following beneficial effects: (1) In the preparation method of the nickel mesh electrode for electrolyzed water of the present invention, the nickel mesh is subjected to infrared preheating treatment, which can reduce the temperature difference between the mixed metal powder or alloy powder and the nickel mesh, reduce the stress of the nickel mesh, and remove moisture, thereby improving the bonding strength between the coating and the nickel mesh and the fatigue resistance of the coating.

[0016] (2) During the activation process of the method of the present invention, stirring the alkali solution with nitrogen can increase the dissolution rate of Al in the coating, thereby preventing aluminum precipitation from clogging the electrolytic cell outlet when the nickel mesh electrode is operated in the electrolytic cell for a long time, thereby improving the overall quality of the nickel mesh; at the same time, the degree of reaction during the activation of the nickel mesh is controlled to reduce safety risks.

[0017] (3) The method of the present invention has the advantages of short process, simple operation and low production cost. The nickel mesh electrode prepared by the method has the characteristics of excellent performance, high bonding strength and low residual aluminum content. DETAILED DESCRIPTION

[0018] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in combination with the specification and preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments. Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0019] Example 1 Step S1: placing a nickel mesh (1m*1m plain nickel mesh) with good weaving quality at the entrance of a sandblasting machine, using 100-mesh white corundum as the abrasive, and sandblasting each nickel mesh for 2 minutes under a sandblasting pressure of 4 bar to obtain a sandblasted nickel mesh; Step S2: Cleaning the nickel mesh after sandblasting in step S1 with a laser cleaner, wherein the parameters of the laser cleaner are: laser pulse frequency of 25kHz, power of 550W, scanning speed of 20mm / s, incident angle of 87°, to obtain a cleaned nickel mesh; infrared heating the cleaned nickel mesh to a nickel mesh temperature of 160°C, and keeping it at this temperature for 2 minutes, to obtain a preheated nickel mesh; Step S3: Put the preheated nickel mesh in step S2 into the spray room, turn on the equipment, and perform plasma spraying, wherein: the spraying powder is a commercially available mechanical mixed powder with a nickel-aluminum mass ratio of 8:2, and the process parameters of plasma spraying are: power of 47kw, powder feeding pressure of 0.45MPa, powder feeding amount of 190g / min, powder feeding gas of nitrogen, plasma spraying gas of argon and hydrogen, both gas pressures of 0.45MPa, argon flow rate of 60 L / min, hydrogen flow rate of 13 L / min; spraying until the nickel mesh gains 260g / m 2 Finally, a nickel mesh containing a coating is obtained.

[0020] Step S4: placing the coated nickel mesh obtained in step S3 in a sodium hydroxide alkaline washing tank with nitrogen stirring for activation treatment; after activation, taking out the nickel mesh, washing it with pure water and drying it, to obtain a nickel mesh electrode. In this step: when placing the nickel mesh, the time interval between the previous nickel mesh and the next nickel mesh is 4 minutes. In this embodiment, a total of 5 nickel meshes are placed at a time, and the placement time of the first nickel mesh and the fifth nickel mesh differs by 16 minutes.

[0021] During activation, the initial concentration of sodium hydroxide in the alkali washing tank is 5wt%. After the first nickel mesh is placed for 2 hours, sodium hydroxide solid is added to the alkali washing tank to make the concentration of the sodium hydroxide solution reach 10wt%. At this concentration, the second activation treatment is carried out for 2 hours; sodium hydroxide is continued to be added to the alkali washing tank liquid to make the concentration of the sodium hydroxide solution reach 15wt%. At this concentration, the third activation treatment is carried out for 2 hours; sodium hydroxide is continued to be added to the alkali washing tank liquid to make the concentration of the sodium hydroxide solution reach 20wt%. At this concentration, the activation treatment is continued for another 6 hours. During the entire activation process, the nitrogen flow rate is 100L / min.

[0022] Comparative Example 1 It is basically the same as Example 1, except that: in step S2, no infrared preheating treatment is performed; that is, the nickel mesh cleaned in step S2 is directly placed in the spraying room in step S3 for spraying treatment.

[0023] Comparative Example 2 The method is basically the same as Example 1, except that in step S4, no nitrogen stirring is performed during the activation process.

[0024] Example 2 It is basically the same as Example 1, except that: in step S2, the infrared preheating step is: infrared heating the cleaned nickel mesh to a nickel mesh temperature of 75°C, and keeping it at this temperature for 2 minutes to obtain a preheated nickel mesh.

[0025] Example 3 It is basically the same as Example 1, except that: in step S2, the infrared preheating step is: infrared heating the cleaned nickel mesh to a nickel mesh temperature of 185°C, and keeping it at this temperature for 2 minutes to obtain a preheated nickel mesh.

[0026] Example 4 It is basically the same as Example 1, except that in step S4, during the activation treatment, the nitrogen flow rate is 50 L / min.

[0027] Example 5 It is basically the same as Example 1, except that in step S4, during the activation treatment, the nitrogen flow rate is 300 L / min.

[0028] Example 6 Step S1: placing a nickel mesh (1m*1m plain nickel mesh) with good weaving quality at the entrance of a sandblasting machine, selecting 100-mesh brown corundum as the abrasive, and sandblasting each nickel mesh for 3 minutes under a sandblasting pressure of 3 bar to obtain a sandblasted nickel mesh; Step S2: Clean the nickel mesh after sandblasting in step S1 with a laser cleaner, wherein: the parameters of the laser cleaner are a laser pulse frequency of 18 kHz, a power of 400 W, a scanning movement speed of 10 mm / s, and an incident angle of 80°, to obtain a cleaned nickel mesh; infrared heat the cleaned nickel mesh to a nickel mesh temperature of 160°C, and keep it at this temperature for 2 minutes to obtain a preheated nickel mesh.

[0029] Step S3: Put the preheated nickel mesh in step S2 into the spray room, turn on the equipment, and perform plasma spraying, wherein: the spraying powder is a nickel-aluminum 9:1 alloy powder sold on the market, and the process parameters of plasma spraying are: power 50kw, powder feeding pressure 0.50MPa, powder feeding amount 250g / min, powder feeding gas nitrogen, plasma spraying gas argon and hydrogen, both gas pressures are 0.35MPa, argon flow rate is 60 L / min, hydrogen flow rate is 8 L / min; spray until the nickel mesh gains 300g / m 2 Finally, a nickel mesh containing a coating is obtained.

[0030] Step S4: placing the coated nickel mesh obtained in step S3 in a sodium hydroxide alkaline washing tank with nitrogen stirring for activation treatment; after activation, taking out the nickel mesh, washing it with pure water and drying it, to obtain a nickel mesh electrode. In this step: when placing the nickel mesh, the time interval between the previous nickel mesh and the next nickel mesh needs to be 3 minutes. In this embodiment, a total of 5 nickel meshes are placed at a time, and the placement time of the first nickel mesh and the fifth nickel mesh differs by 12 minutes.

[0031] During activation, the initial concentration of sodium hydroxide in the alkali washing tank was 4wt%. After the first nickel mesh was placed for 2.5h, solid sodium hydroxide was added to the alkali washing tank to make the concentration of the sodium hydroxide solution reach 9wt%. At this concentration, the second activation treatment was carried out for 2.5h; sodium hydroxide was continued to be added to the alkali washing tank solution to make the concentration of the sodium hydroxide solution reach 14wt%. At this concentration, the third activation treatment was carried out for 2.5h; sodium hydroxide was continued to be added to the alkali washing tank solution to make the concentration of the sodium hydroxide solution reach 19wt%. At this concentration, the activation treatment was continued for another 6h. During the entire activation process, the nitrogen flow rate was 150L / min.

[0032] Example 7 Step S1: placing a nickel mesh (1m*1m plain nickel mesh) with good weaving quality at the entrance of a sandblasting machine, using 100-mesh white corundum as the abrasive, and sandblasting each nickel mesh for 2 minutes at a sandblasting pressure of 4.4 bar to obtain a sandblasted nickel mesh; Step S2: Clean the nickel mesh after sandblasting in step S1 with a laser cleaner, wherein: the parameters of the laser cleaner are a laser pulse frequency of 28kHz, a power of 590W, a scanning movement speed of 25mm / s, and an incident angle of 90°, to obtain a cleaned nickel mesh; infrared heat the cleaned nickel mesh to a nickel mesh temperature of 160°C, and keep it at this temperature for 2 minutes to obtain a preheated nickel mesh.

[0033] Step S3: Put the preheated nickel mesh in step S2 into the spray room, turn on the equipment, and perform plasma spraying, wherein: the spraying powder is a commercially available nickel-aluminum 7:3 alloy powder, and the process parameters of plasma spraying are: power of 30kw, powder feeding pressure of 0.25MPa, powder feeding amount of 110g / min, powder feeding gas of nitrogen, plasma spraying gas of argon and hydrogen, both gas pressures of 0.55MPa, argon flow rate of 45 L / min, hydrogen flow rate of 15 L / min; spraying until the nickel mesh gains 240g / m 2 Finally, a nickel mesh containing a coating is obtained.

[0034] Step S4: placing the coated nickel mesh obtained in step S3 in a potassium hydroxide alkaline washing tank with nitrogen stirring for activation treatment; after activation, taking out the nickel mesh, washing it with pure water and drying it, to obtain a nickel mesh electrode. In this step: when placing the nickel mesh, the time interval between the previous nickel mesh and the next nickel mesh needs to be 2 minutes. In this embodiment, a total of 5 nickel meshes are placed at a time, and the placement time of the first nickel mesh and the fifth nickel mesh differs by 8 minutes.

[0035] During activation, the initial concentration of potassium hydroxide in the alkali washing tank was 6wt%. After the first nickel mesh was placed for 2.0h, potassium hydroxide solid was added to the alkali washing tank to make the concentration of potassium hydroxide solution reach 11wt%. At this concentration, the second activation treatment was carried out for 1.5h; potassium hydroxide was continued to be added to the alkali washing tank solution to make the concentration of potassium hydroxide solution reach 16wt%. At this concentration, the third activation treatment was carried out for 1.5h; potassium hydroxide was continued to be added to the alkali washing tank solution to make the concentration of potassium hydroxide solution reach 21wt%. At this concentration, the activation treatment was continued for another 5h. During the entire activation process, the nitrogen flow rate was 90L / min.

[0036] The bonding strength and electrochemical performance of the nickel mesh electrodes in Examples 1 to 7 and Comparative Examples 1 to 2 were tested; The specific test method is as follows: The test method for the bonding strength is: fold the nickel mesh electrode 180 degrees repeatedly, and count the number of folds when powder falls off.

[0037] Electrochemical performance test: Cyclic voltammetry was used to test the electrochemical performance of the nickel mesh electrode, and its 2 The overpotential for hydrogen evolution at different current densities.

[0038] The test results of the bonding strength and electrochemical performance of the nickel mesh electrodes in Examples 1 to 7 and Comparative Examples 1 to 2 can be seen in Table 1.

[0039] Table 1 From the data in Table 1, it can be seen that the nickel mesh in Comparative Example 1 was not preheated before plasma spraying, and its coating bonding strength was weak, and its corresponding hydrogen evolution overpotential was high. The nickel mesh in Example 1 was infrared preheated before spraying, and its coating bonding performance was significantly improved compared with Comparative Example 1; its hydrogen evolution overpotential was also reduced compared with Comparative Example 1.

[0040] In the activation process of Comparative Example 2, nitrogen stirring was not performed. During the activation process, the aluminum in the coating may not be sufficiently dissolved, and the number of hydrogen evolution sites is small, resulting in a high hydrogen evolution overpotential.

[0041] The preheating temperature of the nickel mesh in Example 2 is lowered, and its bonding ability with the coating is lowered compared with that in Example 1, so its overall performance is slightly reduced. The preheating temperature of the nickel mesh in Example 3 is increased, and its bonding ability with the coating is also reduced compared with that in Example 1. This may be because the preheating temperature is too high, causing a small part of the surface of the nickel mesh to be oxidized, which reduces its bonding ability with the coating and its overall performance is slightly reduced.

[0042] The main difference between Examples 4 and 5 is that the nitrogen flow rate is different during activation. The lower nitrogen flow rate in Example 4 may lead to insufficient aluminum dissolution in the coating and a small number of hydrogen evolution sites, so its hydrogen evolution overpotential is increased compared with Example 1. The higher nitrogen flow rate in Example 5 may have a flushing effect on the porous structure of the nickel mesh surface, reducing the reaction sites, resulting in an increase in its hydrogen evolution overpotential compared with Example 1; and the excessive nitrogen flow rate and excessive stirring effect will affect the bonding strength between the coating and the nickel mesh, reducing the bonding strength of the coating.

[0043] The process parameters for preparing the nickel mesh electrodes in Examples 6 and 7 were adjusted. Overall, the nickel mesh electrodes prepared in Examples 6 and 7 had good comprehensive performance.

[0044] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a nickel mesh electrode for electrolyzing water, characterized in that: The following steps are involved: Step S1: sandblasting the nickel mesh to obtain a sandblasted nickel mesh; Step S2: After cleaning the nickel mesh after sandblasting in step S1, perform infrared preheating treatment to obtain a preheated nickel mesh; Step S3: spraying the mixed metal powder or alloy powder onto the nickel mesh preheated in step S2 by plasma spraying to obtain a nickel mesh containing a metal coating; Step S4: placing the nickel mesh containing the metal coating in step S3 in an alkaline solution, and introducing nitrogen into the alkaline solution for activation. After the activation is completed, washing and drying are performed to obtain a nickel mesh electrode.

2. The method for preparing a nickel mesh electrode for electrolyzing water according to claim 1, wherein: In the step S1, the sandblasting abrasive is white corundum or brown corundum, the sandblasting pressure is 2.6-4.4 bar, and the sandblasting time is 2-4 min.

3. The method for preparing a nickel mesh electrode for electrolyzing water according to claim 1, wherein: In the step S2, laser cleaning is used for cleaning; the laser cleaning parameters are: laser pulse frequency is 15-30kHz, power is 385W-620W, scanning movement speed is 10-25mm / s, and incident angle range is 80-90°.

4. The method for preparing a nickel mesh electrode for electrolyzing water according to claim 1 or 3, characterized in that: In step S2, the specific steps of infrared preheating are: using infrared to heat the nickel mesh to 75-185° C. and keep it warm for 1-5 minutes.

5. The method for preparing a nickel mesh electrode for electrolyzing water according to claim 1, characterized in that: In step S3, the mixed metal powder is a mixed powder composed of nickel powder and aluminum powder, and the mass ratio of nickel powder to aluminum powder is (7-9):(1-3); the alloy powder is nickel-aluminum alloy powder; the mass ratio of nickel to aluminum in the nickel-aluminum alloy powder is (70-90):(10-30).

6. The method for preparing a nickel mesh electrode for electrolyzing water according to claim 1 or 5, characterized in that: In step S3, the process parameters of the plasma spraying method are: spraying power is 30~55kw; powder feeding pressure is 0.15~0.5MPa; powder feeding amount is 100~250g / min, and the powder feeding gas is nitrogen; plasma spraying gas is argon and hydrogen, argon flow rate is 45~60 L / min, argon pressure is 0.3~0.6MPa, hydrogen flow rate is 5~15 L / min, and hydrogen pressure is 0.3~0.6MPa; spraying until the nickel mesh gains 240~300g / m 2 .

7. The method for preparing a nickel mesh electrode for electrolyzing water according to claim 1, characterized in that: In step S4, the alkali solution is a sodium hydroxide solution or a potassium hydroxide solution; the specific steps of activation are: placing the nickel mesh electrode in an alkali solution with an initial concentration of 4-6wt%, and activating for 1.5-2.5h; then adding solid alkali to the alkali solution, adjusting the alkali solution concentration to 8-12wt%, and activating for 1.5-2.5h; adding solid alkali to the alkali solution again, adjusting the alkali solution concentration to 14-16wt%, and activating for 1.5-2.5h; then, adding solid alkali to the alkali solution, adjusting the alkali solution concentration to 19-21wt%, and continuing to activate for 5-9h.

8. The method for preparing a nickel mesh electrode for electrolyzing water according to claim 1 or 7, characterized in that: In step S4, the nitrogen introduction rate is 90-240 L / min.

9. A nickel mesh electrode for electrolyzing water, characterized in that: The method is prepared by any one of claims 1 to 8.

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