Alkali electrolysis water electrode and preparation method thereof

Abstract

The invention belongs to the technical field of electrode preparation, and discloses an alkaline electrolysis water electrode and a preparation method thereof. Comprising the following steps: (1) mixing nickel-based alloy powder and aluminum powder to obtain catalyst powder; (2) spraying catalyst powder on the electrode substrate to form a functional layer; (3) carrying out activating treatment on the sprayed electrode substrate; and (4) carrying out heat treatment on the activated electrode substrate to obtain the alkaline electrolysis water electrode. According to the invention, alloying and mechanization are fused, and finally activation and heat treatment are carried out, so that the prepared alkaline electrolysis water electrode has the advantages of catalytic activity, high stability, high energy efficiency and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of electrode preparation, and specifically relates to an alkaline water electrolysis cathode and a preparation method thereof. Background Art

[0002] The development and promotion of clean energy is imminent. Hydrogen is one of the most common elements in nature, with abundant resources. It only produces water during use, so it is a very clean and efficient secondary energy carrier, which is very consistent with the current energy transformation and new energy system construction needs in my country. Alkaline water electrolysis to produce hydrogen is currently an economical and highly industrialized clean hydrogen production technology.

[0003] Traditional alkaline water electrolysis electrode materials are plate-like or single mesh substrates, which have the following problems: (1) The tiny bubbles generated during the electrolysis process are easily attached to the electrode surface, forming an air film layer that hinders the contact between the electrolyte solution and the electrode, reducing the electrode specific surface area; (2) Although some precious metal electrode materials such as platinum have improved the electrolysis efficiency, the effect is still not obvious, and their cost is too high to be suitable for industrial production; (3) Considering the service life, the working current is often limited to 0.3A·cm -2 Below, more electrolyzers need to be deployed in large-scale application scenarios.

[0004] CN11076087 A discloses a fully solid-state rapid preparation method for alkaline water electrolysis electrodes, which uses high-pressure gas as a kinetic energy carrier for powdered electrode materials, and sprays the powdered electrode materials on the surface of an electrode substrate to form a catalytic layer. However, the functional layer after spraying in this solution has thermal stress, and the coating may fall off during subsequent use, and there are still problems of insufficient catalytic stability and service life.

[0005] CN110846609A discloses a method for preparing an alkaline water electrolysis electrode, wherein the electrode substrate is subjected to sandblasting and degreasing treatment, and the electrode material is sprayed on the electrode substrate by atmospheric plasma spraying to form an electrode functional layer. However, this solution is costly, and the specific surface area of ​​the functional layer is small, resulting in limited catalytic activity. Summary of the invention

[0006] The object of the present invention is to provide an alkaline water electrolysis electrode and a preparation method thereof, so as to solve at least one technical problem existing in the background technology.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is: A method for preparing an alkaline water electrolysis electrode comprises the following steps: (1) Nickel-based alloy powder and aluminum powder are mixed to obtain catalyst powder; (2) Spraying the catalyst powder onto the electrode substrate to form a functional layer; (3) Activating the electrode substrate after spraying; (4) The activated electrode substrate is heat treated to obtain an alkaline water electrolysis electrode.

[0008] The present invention first prepares a composite catalyst powder containing nickel-based alloy and aluminum, and effectively coats it on an electrode substrate, forms a pore structure on the electrode surface through activation treatment, and further optimizes the structure and performance of the electrode through a heat treatment step, and finally obtains an alkaline water electrolysis electrode.

[0009] Furthermore, the mass ratio of the nickel-based alloy powder to the aluminum powder in the catalyst powder is 90-50:10-50.

[0010] Furthermore, the nickel-based alloy powder is an alloy powder of nickel and metal M, and the metal M is at least one of molybdenum, cobalt, and aluminum.

[0011] According to the inventor's research, after aluminum and nickel form an alloy, part of the alloy phase is extremely difficult to dissolve during the activation process. When used as an electrode, the undissolved aluminum will begin to dissolve due to the applied current, and the dissolved aluminum may clog the electrolytic cell, causing an increase in the maintenance cost of the electrolytic cell and simultaneously affecting the life of the electrolytic cell. Based on this hidden danger, the present invention further preferably selects the metal M to be at least one of molybdenum and cobalt, excluding aluminum.

[0012] Furthermore, in the nickel-based alloy powder, the mass ratio of nickel to metal M is 95~50:5~50.

[0013] Furthermore, in step (1), the method for preparing nickel-based alloy powder is as follows: a metal nickel block and a metal M are vacuum-melted and gas-atomized to obtain a nickel-based alloy powder, and the particle size of the nickel-based alloy powder is controlled to be 15-53 μm; vacuum melting and gas-atomization make the nickel-based alloy powder have good fluidity, ensure the uniformity of the alloy composition and the particle size distribution of the alloy powder, and facilitate the subsequent mixing and spraying process.

[0014] Furthermore, the particle size of the aluminum powder is 15-45 μm.

[0015] Furthermore, in step (2), the spraying method is atmospheric plasma spraying.

[0016] Furthermore, when spraying: The plasma gas is a mixture of inert gas and hydrogen; The inert gas flow rate is 45~60L / min; The hydrogen flow rate is 1.3~1.7L / min; The spray powder feeding pressure is 0.25~0.5MPa; The scanning interval of the spray gun is 6~8mm; The spray gun movement speed is 500~1100mm / s; Spraying angle ≥60°; Output power is ≤40KW; The number of spraying times is 1 to 3 times.

[0017] Furthermore, the activation treatment in step (3) includes: soaking in a 10-30 wt% KOH or NaOH solution at 25-60° C. for 4-24 hours.

[0018] Furthermore, the heat treatment temperature of step (4) is 100-300° C. and the heat treatment time is 1-3 h.

[0019] The invention also discloses an alkaline water electrolysis electrode prepared by the preparation method.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The present invention first mixes nickel-based alloy powder with aluminum powder to obtain a catalyst powder with optimized performance. The alloy elements and nickel in the nickel-based alloy powder can achieve multi-element synergistic effects, and in the subsequent process, part of the alloy phase can be dissolved during the activation process to form extremely fine pores. Doping with aluminum powder can further achieve pore formation, increase the specific surface area of ​​the functional layer, and provide more active sites. The extremely fine pores formed by the alloy powder and the holes formed by the pore-forming agent are evenly distributed, thereby improving the adsorption and desorption capabilities, thereby improving the hydrogen production capacity.

[0021] The present invention mixes nickel-based alloy powder and aluminum powder and then sprays them on the electrode substrate to form a high-functional layer, which can provide more active sites, thereby enhancing the electrochemical performance of the electrode. While ensuring the electrolysis reaction sites, the uniform mixing also makes the pores and microporous structures in the pore structure formed by the subsequent activation treatment more evenly distributed, achieving efficient mass transfer and exhaust.

[0022] The present invention activates the electrode substrate after spraying to form a pore structure on the surface, thereby increasing the activity of the electrode surface and improving the reaction efficiency of the electrode. Subsequent heat treatment further stabilizes the structure of the electrode, making the pores more uniform and stable, reducing hydrogen embrittlement, improving the mechanical properties of the electrode, and extending the service life of the electrode.

[0023] The preparation process of the present invention can realize the preparation of high-efficiency and high-performance electrodes, and improves the shortcomings of the electrode preparation process, such as high difficulty, low preparation efficiency, and low performance of the prepared electrodes.

[0024] The present invention combines alloying with mechanization, and finally performs activation and heat treatment, so that the alkaline water electrolysis electrode prepared has the advantages of catalytic activity, high stability, high energy efficiency and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0026] In the attached picture: Figure 1 This is the volt-ampere characteristic curve of the electrode obtained in Example 1.

[0027] Figure 2 This is the volt-ampere characteristic curve of the electrode obtained in Example 2.

[0028] Figure 3 This is the volt-ampere characteristic curve of the electrode obtained in Example 3.

[0029] Figure 4 This is the volt-ampere characteristic curve of the electrode obtained in Example 4.

[0030] Figure 5 This is the volt-ampere characteristic curve of the electrode obtained in Example 5.

[0031] Figure 6 This is the volt-ampere characteristic curve of the electrode obtained in Example 6.

[0032] Figure 7 This is a microscopic morphology of the electrode obtained in Example 2.

[0033] Figure 8 This is a microscopic morphology of the electrode obtained in Example 3.

[0034] Fig. 9 This is a microscopic morphology of the electrode obtained in Example 6. DETAILED DESCRIPTION

[0035] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully in combination with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0036] 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.

[0037] 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.

[0038] Example 1 Nickel block / molybdenum block = 90wt.% / 10wt.% was used for vacuum melting and gas atomization, and then the alloy powder with a particle size of 15~53μm and d50=28.5μm was screened by a vibrating screen.

[0039] Nickel-molybdenum alloy powder / aluminum powder = 90wt.% / 10wt.% were mixed by a double cone mixer at a mixing frequency of 40 Hz and a mixing time of 30 min to obtain catalyst powder.

[0040] The woven nickel mesh substrate was sandblasted and then the catalyst powder was sprayed on the substrate by atmospheric plasma spraying to form a functional layer. The spraying argon flow rate was 58 L / min, the hydrogen flow rate was 1.5 L / min, the powder feeding pressure was 0.45 MPa, the spray gun scanning interval was 8 mm, the spray gun moving speed was 950 mm / s, the spraying angle was 60°, the output power was 40 kW, and the spraying was performed twice.

[0041] The sprayed electrode was immersed in a flowing 10wt% NaOH solution for 4 hours, then washed with pure water until there was no solid residue on the surface, blown dry with electrical equipment, and then kept at 100°C for 1 hour to obtain a water electrolysis electrode with uniform surface color.

[0042] Example 2 Nickel block / molybdenum block = 90wt.% / 10wt.% was used for vacuum melting and gas atomization, and then 15~53μm was screened by a vibrating screen, where d50 = 28.5μm to obtain alloy powder.

[0043] Nickel-molybdenum alloy powder / aluminum powder = 80wt.% / 20wt.% were mixed by a double cone mixer at a mixing frequency of 40 Hz and a mixing time of 30 min to obtain catalyst powder.

[0044] The woven nickel mesh substrate was sandblasted and then the catalyst powder was sprayed on the substrate by atmospheric plasma spraying to form a functional layer. The spraying argon flow rate was 58 L / min, the hydrogen flow rate was 1.0 L / min, the powder feeding pressure was 0.3 MPa, the spray gun scanning interval was 8 mm, the spray gun moving speed was 900 mm / s, the spraying angle was 70°, the output power was 39 KW, and the spraying was performed twice.

[0045] The sprayed electrode was immersed in a flowing 10wt% NaOH solution for 8 hours, then washed with pure water until there was no solid residue on the surface, blown dry with electrical equipment, and then kept at 200°C for 2 hours to obtain a water electrolysis electrode with uniform surface color.

[0046] Example 3 Nickel block / molybdenum block = 90wt.% / 10wt.% was used for vacuum melting and gas atomization, and then 15~53μm was screened by a vibrating screen, where d50 = 28.5μm to obtain alloy powder.

[0047] Nickel-molybdenum alloy powder / aluminum powder = 70wt.% / 30wt.% were mixed by a double cone mixer at a mixing frequency of 40 Hz and a mixing time of 30 min to obtain catalyst powder.

[0048] The woven nickel mesh substrate was sandblasted and then the catalyst powder was sprayed on the substrate by atmospheric plasma spraying to form a functional layer. The spraying argon flow rate was 48 L / min, the hydrogen flow rate was 0.8 L / min, the powder feeding pressure was 0.3 MPa, the spray gun scanning interval was 8 mm, the spray gun moving speed was 850 mm, the spray angle was 80°, the output power was 34 KW, and the spraying was done twice.

[0049] The sprayed electrode was immersed in a flowing 10wt% NaOH solution for 12 hours, then washed with pure water until there was no solid residue on the surface, blown dry with electrical equipment, and then kept at 300°C for 3 hours to obtain a water electrolysis electrode with uniform surface color.

[0050] Example 4 Nickel block / aluminum block = 50wt.% / 50wt.% was used for vacuum melting and gas atomization, and then 15~53μm was screened by a vibrating screen, where d50=28.5μm to obtain alloy powder.

[0051] Nickel aluminum alloy powder / aluminum powder = 80wt.% / 20wt.% were mixed by a double cone mixer at a mixing frequency of 40 Hz and a mixing time of 30 min to obtain catalyst powder.

[0052] The woven nickel mesh substrate was sandblasted and then the catalyst powder was sprayed on the substrate by atmospheric plasma spraying to form a functional layer. The spraying argon flow rate was 48 L / min, the hydrogen flow rate was 0.8 L / min, the powder feeding pressure was 0.25 MPa, the spray gun scanning interval was 8 mm, the spray gun moving speed was 950 m / s, the spraying angle was 60°, the output power was 35 KW, and the spraying was done twice.

[0053] The sprayed electrode was immersed in a flowing 10wt% NaOH solution for 16 hours, then washed with pure water until there was no solid residue on the surface, blown dry with electrical equipment, and then kept at 200°C for 2 hours to obtain a water electrolysis electrode with uniform surface color.

[0054] Example 5 Nickel block / aluminum block = 50wt.% / 50wt.% was used for vacuum melting and gas atomization, and then 15~53μm was screened by a vibrating screen, where d50=28.5μm to obtain alloy powder.

[0055] Nickel aluminum alloy powder / aluminum powder = 70wt.% / 30wt.% were mixed by a double cone mixer at a mixing frequency of 40 Hz and a mixing time of 30 min to obtain catalyst powder.

[0056] The woven nickel mesh substrate was sandblasted and then the catalyst powder was sprayed on the substrate by atmospheric plasma spraying to form a functional layer. The spraying argon flow rate was 48 L / min, the hydrogen flow rate was 0.8 L / min, the powder feeding pressure was 0.3 MPa, the spray gun scanning interval was 8 mm, the spray gun moving speed was 800 mm / s, the spraying angle was 60°, the output power was 30 KW, and the spraying was done twice.

[0057] The sprayed electrode was immersed in a flowing 10wt% NaOH solution for 24 hours, then washed with pure water until there was no solid residue on the surface, dried with electrical equipment, and then kept at 300°C for 3 hours to obtain a water electrolysis electrode with uniform surface color.

[0058] Example 6 Nickel block / cobalt block = 95wt.% / 5wt.% was used for vacuum melting and gas atomization, and then 15~53μm was screened by a vibrating screen, where d50 = 28.5μm to obtain alloy powder.

[0059] Nickel-cobalt alloy powder / aluminum powder = 80wt.% / 20wt.% were mixed by a double cone mixer at a mixing frequency of 40 Hz and a mixing time of 30 min to obtain catalyst powder.

[0060] The woven nickel mesh substrate was sandblasted and then the catalyst powder was sprayed on the substrate by atmospheric plasma spraying to form a functional layer. The spraying argon flow rate was 48 L / min, the hydrogen flow rate was 0.8 L / min, the powder feeding pressure was 0.3 MPa, the spray gun scanning interval was 8 mm, the spray gun moving speed was 1000 mm / s, the spraying angle was 60°, the output power was 35 KW, and the spraying was performed twice.

[0061] The sprayed electrode was immersed in a flowing 10wt% NaOH solution for 8 hours, then washed with pure water until there was no solid residue on the surface, blown dry with electrical equipment, and then kept at 200°C for 2 hours to obtain a water electrolysis electrode with uniform surface color.

[0062] Preparation of 30wt% electrical performance test solution: Use a beaker to weigh 33.3g of 90% pure KOH, add deionized water to dissolve it until the total weight is 100g, and let it stand until the solution is non-gelatinous.

[0063] The electrodes obtained from Examples 1 to 6 were randomly cut into 0.5 cm 2As the test sample, the pure nickel mesh electrode substrate was used as a comparison sample. The CV test was first performed at a voltage range of 0~1.5v and a scanning speed of 50mV / s, and then the LSV test was performed at a voltage range of 0~1.4 and a scanning speed of 5mV / s. The cyclic voltammetric characteristic curve of the test electrode was collected by the electrochemical workstation, and the repeatability test was performed, and the curves were plotted respectively. Figures 1 to 6 The volt-ampere characteristic curve is shown.

[0064] It can be seen that compared with the pure nickel mesh electrode substrate control sample, the performance of the electrodes obtained in Examples 1 to 6 is greatly improved, and after repeated cyclic testing, it has good stability. The electrochemical performance does not change much on the 1st day, the 7th day, and the 45th day, and has a better service life.

[0065] Figure 7~Figure 9 The scanning electron microscope images of the electrode surfaces obtained in Examples 2, 3, and 6 respectively show that the specific surface area of ​​the electrode is relatively high, the functional layer on the electrode surface has dense pores and hole structures, the pores are irregular in shape and relatively evenly distributed in the cross section, the pores have good connectivity, and there are many small microchannels.

[0066] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the present invention.

Claims

1. A method for preparing an alkaline water electrolysis electrode, characterized in that: The following steps are involved: (1) Nickel-based alloy powder and aluminum powder are mixed to obtain catalyst powder; (2) Spraying the catalyst powder onto the electrode substrate to form a functional layer; (3) Activating the electrode substrate after spraying; (4) The activated electrode substrate is heat treated to obtain an alkaline water electrolysis electrode.

2. The preparation method according to claim 1, characterized in that The mass ratio of the nickel-based alloy powder to the aluminum powder in the catalyst powder is 90-50:10-50.

3. The preparation method according to claim 1, characterized in that: The nickel-based alloy powder is an alloy powder of nickel and metal M, and the metal M is at least one of molybdenum, cobalt, and aluminum.

4. The preparation method according to claim 3, characterized in that: The metal M does not include aluminum.

5. The preparation method according to claim 3, characterized in that: The mass ratio of nickel to metal M in the nickel-based alloy powder is 95-50:5-50.

6. The preparation method according to any one of claims 1 to 5, characterized in that: In step (1), the method for preparing the nickel-based alloy powder comprises vacuum melting and gas atomizing a metal nickel block and a metal M to obtain the nickel-based alloy powder; and controlling the particle size of the nickel-based alloy powder to be 15-53 μm; The particle size of the aluminum powder is 15-45 μm.

7. The preparation method according to claim 1, characterized in that: In step (2), the spraying method is atmospheric plasma spraying; during spraying: The plasma gas is a mixture of inert gas and hydrogen; The inert gas flow rate is 45~60L / min; The hydrogen flow rate is 1.3~1.7L / min; The spray powder feeding pressure is 0.25~0.5MPa; The scanning interval of the spray gun is 6~8mm; The spray gun movement speed is 500~1100mm / s; Spraying angle ≥60°; Output power is ≤40KW; The number of spraying times is 1 to 3 times.

8. The preparation method according to claim 1, characterized in that: The activation treatment in step (3) includes: soaking in a 10-30 wt% KOH solution or NaOH solution at 25-60° C. for 4-24 hours.

9. The preparation method according to claim 1, characterized in that: The heat treatment temperature of step (4) is 100-300°C; the heat treatment time is 1-3h.

10. An alkaline water electrolysis electrode prepared by the preparation method according to any one of claims 1 to 9.

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