CN116377551A - Integrated electrode for alkaline electrolyzer, preparation method of electrode and electrolyzer - Google Patents

Abstract

The invention relates to an integrated electrode for an alkaline electrolytic cell, a preparation method of the electrode and an electrolytic cell, wherein the preparation method comprises the following steps: A) arranging the nickel felt, the nickel mesh electrode, and the nickel mesh flow field in sequence, and using a laser Welding technology is integrated; B) In the two-electrode system, the aqueous solution of nickel-iron metal salt is used as the electroplating solution, the integrated electrode welded in step A) is used as the working electrode, and the platinum sheet is used as the counter electrode. A nickel-iron hydroxide deposition layer is electrodeposited on the surface to obtain an integrated electrode for an alkaline electrolyzer. Compared with the prior art, the laser welding and other technologies used in the integration of the present invention and the electro-deposition technology attached to the catalyst have a good industrialization prospect, and can be manufactured by automatic processing, and the assembly structure of the electrolytic cell can be optimized by using the electrode , reducing the size and maintaining high electrode reactivity, good economic benefits and high practical value.

Description

Integrated electrode for alkaline electrolyzer, preparation method of electrode and electrolyzer

technical field

The invention relates to the technical field of electrolytic hydrogen production, in particular to an integrated electrode for an alkaline electrolytic cell, a preparation method of the electrode and an electrolytic cell.

Background technique

As an excellent energy carrier, hydrogen will play an important role in the future world energy system. The advantage of hydrogen is that its theoretical combustion product is only water, which means that there are no carbon monoxide, carbon dioxide and other substances harmful to the environment, and it will not produce acid rain, deplete ozone or produce harmful emissions. Therefore, hydrogen is a clean fuel, and hydrogen energy can also be produced using renewable energy (such as wind energy, solar energy, hydropower, etc.), which makes hydrogen energy one of the core concerns in the current energy field.

Large-scale hydrogen promotion requires large-scale hydrogen production, generally through electrolysis of water to achieve clean hydrogen production. Alkaline electrolytic hydrogen production is the most widely used electrolytic water technology. It is also called alkaline aqueous solution electrolytic hydrogen production technology. It uses strong alkali as the electrolyte and is characterized by a porous diaphragm. This technology is the earliest electrolyzed water technology discovered and applied, and it has a history of more than 100 years of industrial application. But in the traditional alkaline water electrolyzer, there is a distance between the electrode and the diaphragm, and the hydrogen and oxygen generated on the electrode will exist in the form of bubbles and accumulate in the gap during the electrolysis process. Accumulation of gas bubbles can lead to covering of the active sites on the electrode surface and an increase in the actual resistance of the electrolyte, which in turn manifests itself as a decrease in the performance of the electrolyzer.

Therefore, the "zero-gap electrolytic cell concept" is currently proposed. In this electrolytic cell, due to the compression of elastic elements, the cathode and anode are assembled against the diaphragm. This design can reduce the resistance of the electrolytic cell and significantly improve efficiency. . However, the electrode structure of the current industrial electrolyzer is rough, and the mechanical properties of the diaphragm are poor. The mutual contact and extrusion may easily cause the rupture of the diaphragm and lead to a short circuit, and the risk is high. At present, the related patents of zero-gap electrolyzer are mainly concentrated on chlor-alkali electrolyzer. Chinese invention CN201980038703.4 discloses a zero-gap electrolytic cell with elastic holding elements, in which the anode, ion exchange membrane and cathode are in direct contact, and a flexible elastic holding element is arranged on the other side of the anode and/or cathode. This patent is mainly aimed at chlor-alkali electrolysis or hydrochloric acid electrolysis. The device uses a holding element to press the electrode and the ion exchange membrane together. The ring-shaped holding element prevents the lateral displacement of the diaphragm by controlling the direction of the pressing force, but the current research has not focused on the gap between the diaphragm and the electrode. Risk of diaphragm damage due to possible internal pinching.

Therefore, in view of the problems existing in the assembly of electrodes and diaphragms in existing electrolyzers, it is urgent to design a new zero-gap main plate-electrode-diaphragm design, which can maintain high electrode reactivity while optimizing its electrolyzer assembly structure.

Contents of the invention

The purpose of the present invention is to provide an integrated electrode for alkaline electrolyzers in order to overcome the defects of the above-mentioned prior art. By using the electrode, the assembly structure of the electrolyzer can be optimized, and the size can be reduced while maintaining high electrode reactivity. , better economic benefits, higher practical value.

The purpose of the present invention can be achieved through the following technical solutions:

A first aspect of the present invention provides a method for preparing an integrated electrode for an alkaline electrolyzer, comprising the following steps:

A) Arrange the nickel felt, nickel mesh electrode, and nickel mesh flow field in sequence, and use laser welding technology for integrated integration;

B) In the two-electrode system, the aqueous solution of nickel-iron metal salt is used as the electroplating solution, the integrated electrode welded in step A) is used as the working electrode, and the platinum sheet is used as the counter electrode, and a layer of nickel-iron is electrodeposited on the surface of the welded integrated electrode Hydroxide deposition layer to obtain integrated electrodes for alkaline electrolyzers.

Further, the thickness of the nickel felt is 0.5-2mm;

The nickel wire diameter of the nickel mesh electrode is 20-2000um, and the mesh number of the nickel mesh electrode is 50-600 mesh.

Further, the diameter of the nickel wire in the nickel mesh flow field is 20-2000um, and the mesh number of the nickel mesh flow field is 50-600 mesh.

Further, the nickel felt, the nickel mesh electrode, and the nickel mesh flow field are all pretreated materials, and the pretreatment process is: ultrasonic treatment in dilute hydrochloric acid to remove surface oxides, and then in absolute ethanol Sonication removes hydrochloric acid and organics from the surface, and finally sonication in deionized water removes other remaining impurities on the surface.

Further, the concentration of the dilute hydrochloric acid is 0.5-1.2 mol/L, and the time of the ultrasonic treatment is 15 minutes.

Further, in the electroplating solution described in step B), the concentration of nickel chloride is 0.8-1.2 mol/L, and the concentration of ferrous chloride is 0.4-0.6 mol/L.

Further, in step B), the electrodeposition is carried out in a deposition tank, the electrodeposition time is 10 minutes, the current density is uniformly increased from 1A/cm ² to 3A/cm ² within 10 minutes, and the temperature is 20- 30°C.

Further, in step B), after the electrodeposition, it also includes: washing and drying, specifically including: rinsing the electrodeposited composite material with deionized water, then rinsing with absolute ethanol, and then drying naturally.

The second aspect of the present invention provides an integrated electrode prepared by the above method, including sequential laser welding:

Nickel felt: set between the electrode and the diaphragm, it acts as a buffer on the material, avoids the diaphragm from being damaged by impact or friction, and promotes the electrolysis efficiency through the high specific surface area of the nickel felt;

Nickel mesh electrode: electrolyze water and generate oxygen or hydrogen on the electrode surface;

Nickel mesh flow field: promote the electrolysis reaction, and at the same time form the flow field area of the electrolysis chamber with the main plate on the other side.

It also includes a nickel-iron hydroxide deposition layer compounded on the surface of the integrated electrode.

The third aspect of the present invention provides an electrolytic cell, comprising the above-mentioned integrated electrode.

Compared with the prior art, the present invention has the following technical advantages:

(1) Compact structure, the present invention utilizes laser welding technology to carry out integrated welding to nickel felt, nickel mesh electrode, nickel mesh flow field, has obtained " nickel felt-nickel mesh electrode-nickel mesh flow field " integration of zero-gap structure The integrated electrodes are integrated, which greatly reduces the ohmic impedance of the electrodes. In addition, this zero-gap electrode also provides a basis for the subsequent manufacture of zero-gap alkaline water hydrogen production electrolyzers.

(2) High catalytic activity. In the integrated electrode of the present invention, structures such as nickel felt, nickel mesh electrode, and nickel mesh flow field all have larger reaction surface areas, and the nickel-iron hydroxide deposition evenly covered on the integrated electrode surface The layer also has good catalytic activity for alkaline electrolysis of water, so that the entire electrode achieves a high catalytic performance for electrolysis of water.

(3) On the whole, a kind of integrated electrode for alkaline electrolyzer proposed by the present invention is very suitable for industrial water electrolysis, no matter in terms of preparation simplicity, economy, catalytic performance and structural features It is far superior to the use of the existing alkaline electrolyzer electrode preparation technology in industrial electrolyzed water, and greatly improves the economic benefits of industrially electrolyzed water.

Description of drawings

Fig. 1 is the structural representation of integrated electrode among the present invention;

Fig. 2 is a schematic diagram of the overall structure of the electrolytic cell equipment in the embodiment of the present invention.

In the figure, 1 is the nickel felt, 2 is the electrode, 3 is the nickel mesh flow field, 4 is the diaphragm, 5 is the anode terminal, 6 is the oxygen outlet, 7 is the nickel felt on the anode side, 8 is the anode electrode, and 9 is the anode side Nickel mesh plate, 10 is the elastic element, 11 is the liquid outlet, 12 is the liquid inlet, 13 is the tank body, 14 is the cathode side nickel mesh plate, 15 is the cathode electrode, 16 is the cathode side nickel felt, 17 is Hydrogen outlet, 18 is the cathode terminal.

Detailed ways

The invention is characterized in that the nickel felt, the electrode and the nickel mesh flow field are combined into an integrated electrode. The purpose of the present invention is to overcome the problem that the excessive distance between the electrode and the diaphragm that exists in the traditional alkaline water electrolyzer causes the accumulation of bubbles, and then shows the problem of the performance decline of the electrolyzer; The performance is poor. When the zero-gap assembly is used, the electrodes and the diaphragm are in contact with each other and squeezed, which will cause problems such as diaphragm rupture and short circuit.

In the present invention, in the "nickel felt-nickel mesh electrode-nickel mesh flow field" laser-welded integrated integrated electrode obtained by laser welding, when subjected to an external force such as the pressing force of an elastic element, the soft structure of the inner nickel felt can The force is evenly distributed to the diaphragm, so as to avoid strong impact on the diaphragm and prevent the diaphragm from being damaged. At the same time, the nickel felt also avoids direct contact between the electrode and the diaphragm, prevents friction between the rough electrode surface and the diaphragm, and reduces the possibility of diaphragm tearing. In addition, in actual work, the thinner thickness of the nickel felt itself will not destroy the zero-gap configuration, and the high specific surface area of the nickel felt itself will further promote the electrolytic reaction, so that zero-gap assembly can be achieved without causing diaphragm rupture . Therefore, it can effectively alleviate the problem of accumulation of air bubbles caused by the distance between the electrode and the diaphragm in the traditional alkaline water electrolyzer, which in turn leads to the performance degradation of the electrolyzer. In addition, the integrated welding reduces the ohmic internal resistance of the electrode.

After electroplating, the surface of the integrated electrode is uniformly attached with an ultra-thin nickel-iron hydroxide deposition layer. The ultra-thin deposition layer not only does not affect electron transport and electrode assembly, but also exhibits excellent catalytic activity for electrolysis of water. Therefore, the integrated electrode for alkaline electrolyzer provided by the present invention has an integrated structure, smaller ohmic impedance and better catalytic activity.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The features such as component models, material names, connection structures, control methods, algorithms, etc. that are not clearly stated in this technical solution are regarded as common technical features disclosed in the prior art.

In order to further illustrate the present invention, the integrated electrode for alkaline electrolyzer provided by the present invention, its preparation method and application are described in detail below in conjunction with the examples, but it should not be understood as limiting the protection scope of the present invention.

The preparation method for the integrated electrode of alkaline electrolyzer in the present embodiment, comprises the following steps:

A) Arrange the nickel felt, nickel mesh electrode, and nickel mesh flow field in sequence, and use laser welding technology for integrated integration;

B) In the two-electrode system, nickel-iron metal salt electroplating solution is used, the integrated electrode welded in step A) is used as the working electrode, and the platinum sheet is used as the counter electrode, and a layer of nickel-iron hydroxide is electrodeposited on the surface of the welded integrated electrode deposited layers, resulting in an integrated electrode for alkaline electrolyzers

In this embodiment, the nickel felt in step A) is a pretreated nickel felt, and the thickness of the nickel felt is 0.5mm.

In this embodiment, the nickel mesh electrode in step A) is a pretreated nickel mesh electrode; the nickel wire diameter of the nickel mesh electrode is 200um, and the mesh number of the nickel mesh electrode is 100 mesh.

The above specific parameters can be adjusted appropriately based on the specific implementation process.

In some embodiments of the present invention, the nickel mesh is a pretreated nickel mesh. The nickel mesh after the pretreatment is prepared according to the following method:

The nickel mesh was ultrasonically treated in dilute hydrochloric acid to remove surface oxides, then ultrasonically treated in absolute ethanol to remove surface hydrochloric acid and organic matter, and finally ultrasonically treated in deionized water to remove other residual impurities on the surface.

In some embodiments of the present invention, the concentration of the dilute hydrochloric acid is 0.5-1.2 mol/L; specifically, it may be 1 mol/L. The time for the ultrasonic treatment at the optimum temperature during implementation is 15 minutes. The nickel felt, the nickel mesh electrode, and the nickel mesh flow field were first ultrasonically treated in dilute hydrochloric acid, then ultrasonically treated in absolute ethanol, then ultrasonically treated in deionized water, and finally dried naturally.

In this embodiment, in the nickel-iron metal salt electroplating solution in step B), the concentration of nickel chloride is 0.8-1.2 mol/L, and the concentration of ferrous chloride is 0.4-0.6 mol/L.

In this embodiment, the electrodeposition in step B) is carried out in a deposition tank. The electrodeposition time is 10 minutes, the current density is uniformly increased from 1A/cm ² to 3A/cm ² within 10 minutes, and the temperature is 20-30°C; specifically, the optimal temperature during implementation may be 25°C.

In this embodiment, after the electrodeposition described in step B), it also includes: washing and drying; specifically includes: rinsing the electrodeposited composite material with deionized water, then rinsing with absolute ethanol, and then Let dry naturally. The number of times of washing may be 3 to 5 times; specifically, it may be 3 times. Each flushing time is 10-30s; specifically, it may be 20s. The water flow rate for rinsing should be moderate and not cause damage to the electrodeposited structure.

The effect of each main component in the integrated electrode of the present invention:

Nickel felt: It is installed between the electrode and the diaphragm to act as a buffer to prevent the diaphragm from being damaged by impact or friction. At the same time, the high specific surface area of the nickel felt can promote the electrolysis efficiency.

Electrode: The electrode where the redox reaction occurs in electrolysis, electrolyzes water and generates oxygen or hydrogen on the electrode surface.

Nickel mesh flow field: a part of the main plate, its high specific surface area can promote the electrolysis reaction, and at the same time form the flow field area of the electrolysis chamber with the main plate on the other side.

Fig. 2 is an explanatory schematic diagram for the first embodiment of the present invention, showing a cross-sectional view of an alkaline water electrolyzer using integrated electrodes. When the electrolyzer is used for electrolysis, potassium hydroxide or sodium hydroxide with a mass fraction of 25%-35% is used as the electrolytic solution. The electrolyte enters the electrolytic cell body 13 through the liquid inlet 12 and leaves the cell body 13 through the liquid outlet 11 . The external power supply inputs current to the anode electrode 8 through the anode terminal 5, passes through the electrolyte, the anode-side nickel felt 7, the diaphragm 3, passes through the cathode-side nickel felt 16 and the cathode electrode 15, and then outputs through the cathode terminal 18 to carry out the electrolysis process. The hydrogen produced in the electrolysis process is discharged through the hydrogen channel 17 , and the produced oxygen is discharged through the oxygen channel 6 .

As shown in Figure 2, the electrolyzer device of the present invention design comprises end shell plate, anode side nickel mesh 9, cathode side nickel mesh 14, anode electrode 8, cathode electrode 15, nickel felt 1 and diaphragm 4, diaphragm 4 is arranged on anode Between the electrode 8 and the cathode electrode 15, the nickel felt 1 is arranged between the anode electrode 8/cathode electrode 15 and the diaphragm 4, which are respectively integrated with the anode electrode 8/cathode electrode 15 and the anode side nickel mesh 9/cathode side nickel mesh 15 chemical electrode. The end shell plates include an anode end shell plate and a cathode end shell plate, which are integrated at both ends of the tank body 13 . Elastic retaining elements 10 are arranged between the cathode end shell and the cathode electrode and between the anode end shell and the anode electrode. The elastic retaining element 10 acts as a helical spring. On the one hand, it is fixed on the end shell plate and fastened to the tank body 13; Apply pressure in the axial direction, ie extending in the direction perpendicular to the electrodes. During specific installation, the nickel felt 1 and the anode electrode 8/cathode electrode 15 and the anode side nickel mesh 9/cathode side nickel mesh 15 are welded into an integrated anode/cathode electrode first, and then according to the cathode end shell plate, the integrated cathode electrode, The diaphragm 4 , the integrated anode electrode and the anode end shell are assembled sequentially, and finally integrated on the tank body 13 .

The above-mentioned electrolytic cell is characterized in that, during specific implementation, the integrated anode electrode, diaphragm 3, and integrated cathode electrode are pressed together by the elastic element 10 fixed on the cell body 13 to form a zero-gap configuration. In the integrated electrode, a layer of smooth nickel felt is provided near the side of the diaphragm, and the electrolytic cell can effectively store the diaphragm between the nickel felts on both sides to improve the working stability of the diaphragm. During actual installation, a nickel felt slightly larger than the size of the diaphragm is provided to ensure the ease of diaphragm installation and the complete storage of the diaphragm by the nickel felt. Therefore, the diaphragm is contained in the nickel felt and is not exposed, and is not subject to local impact and friction. When subjected to an external force such as the compression force of an elastic element, the soft structure inside the nickel felt can evenly distribute the force to the diaphragm, thereby avoiding a strong impact on the diaphragm and preventing the diaphragm from being damaged. Due to the use of a nickel felt slightly larger than the size of the separator, the electrodes will not be able to directly contact the surface of the separator, and the rough electrode surface will only be in contact with the buffer structure. In actual work, by setting the nickel felt with a thickness of ≤0.5mm, the thinner thickness will not destroy the zero-gap configuration of the electrolytic cell, and at the same time, the high specific surface area of the nickel felt itself is used to further promote the electrolytic reaction. At the same time, the nickel-iron hydroxide deposition layer on the surface of the integrated electrode can also effectively catalyze the reaction and improve the hydrogen production efficiency.

In the alkaline water electrolytic cell used in the second embodiment, the cell body 13 is a square sheet metal structure, and the left and right sides above the cell body 13 are respectively provided with a hydrogen channel 17 and an oxygen channel 6, and the middle part outside the cell body is left and right Cathode terminal 18 and anode terminal 5 are installed on both sides. An insulating sleeve is provided outside the terminal. Both sets of terminal are connected to the tank body 13. The top is respectively connected to the pulse voltage generator through wires. The left side of the tank body is The lower part is provided with a liquid inlet 12, and the lower part of the right side of the tank body is provided with a liquid outlet 11. Wherein the top of cathode terminal 18 and anode terminal 5 can be connected with pulse voltage generator by wire; Liquid inlet 12 can be connected with water pump, electrolyte storage tank, input electrolyte is potassium hydroxide or sodium hydroxide solution; The liquid port 11 can be connected to the waste liquid collection box; the hydrogen channel 17 and the oxygen channel 6 can be connected to devices such as gas purification and drying.

In the alkaline water electrolyzer used in the second embodiment, the cathode 15/anode 8 is made of a conductive electrode material, and nickel composite electrodes such as nickel-plated iron plates and nickel alloys are used; the diaphragm 4 can be polysulfone various types of diaphragms such as polyether, PTFE, PPS and composite inorganic diaphragms; the elastic retaining element 10 is an elastic corrugated net made of finely woven nickel wire; the nickel felt is made of nickel wire fibers , thickness ≤ 0.5mm, the wire diameter is related to the specific selected pore size, the overall porosity is between 50% and 90%, the surface is smooth and burr-free, and any existing commercially available nickel felt that meets the above requirements can be used Used in this embodiment; the nickel mesh flow field can be an existing commercially available nickel mesh such as nickel wire woven mesh, nickel plate (or nickel foil) stretched mesh, nickel foil punched mesh, and nickel wire knitted mesh.

During specific implementation, the integrated electrode designed in the present invention can also be applied in a pressurized system.

During specific implementation, the integrated electrode designed by the present invention can be used not only in single-stage electrolytic cells, but also in multi-stage electrolytic cells.

The above descriptions of the embodiments are for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative efforts. Therefore, the present invention is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (10)

1. a preparation method for an integrated electrode of an alkaline electrolyzer, is characterized in that, comprises the following steps: A) Arrange the nickel felt, nickel mesh electrode, and nickel mesh flow field in sequence, and use laser welding technology for integrated integration; B) In the two-electrode system, the aqueous solution of nickel-iron metal salt is used as the electroplating solution, the integrated electrode welded in step A) is used as the working electrode, and the platinum sheet is used as the counter electrode, and a layer of nickel-iron is electrodeposited on the surface of the welded integrated electrode Hydroxide deposition layer to obtain integrated electrodes for alkaline electrolyzers. 2. a kind of preparation method for the integrated electrode of alkaline electrolyzer according to claim 1, is characterized in that, the thickness of described nickel felt is 0.5-2mm; The nickel wire diameter of the nickel mesh electrode is 20-2000um, and the mesh number of the nickel mesh electrode is 50-600 mesh. 3. a kind of preparation method for the integrated electrode of alkaline electrolyzer according to claim 1, is characterized in that, the nickel wire diameter of described nickel mesh flow field is 20-2000um, and described nickel mesh flow field The mesh number of the field is 50-600 mesh. 4. a kind of preparation method for the integrated electrode of alkaline electrolyzer according to claim 1, is characterized in that, described nickel felt, nickel mesh electrode, nickel mesh flow field are the material after pretreatment, The pretreatment process is: ultrasonic treatment in dilute hydrochloric acid to remove surface oxides, then ultrasonic treatment in absolute ethanol to remove surface hydrochloric acid and organic matter, and finally ultrasonic treatment in deionized water to remove other residual impurities on the surface. 5. a kind of preparation method for the integrated electrode of alkaline electrolyzer according to claim 4, is characterized in that, the concentration of described dilute hydrochloric acid is 0.5～1.2mol/L, and the time of described ultrasonic treatment is 15min. 6. A kind of preparation method for the integrated electrode of alkaline electrolyzer according to claim 1, is characterized in that, in step B) in the electroplating solution, the concentration of nickel chloride is 0.8～1.2mol/ L, the concentration of ferrous chloride is 0.4～0.6mol/L. 7. a kind of preparation method for the integrated electrode of alkaline electrolyzer according to claim 1, is characterized in that, in step B), described electrodeposition is carried out in deposition tank, and the time of described electrodeposition within 10 minutes, the current density increases uniformly from 1A/cm ² to 3A/cm ² within 10 minutes, and the temperature is 20-30°C. 8. A method for preparing an integrated electrode for an alkaline electrolyzer according to claim 1, characterized in that, in step B), after the electrodeposition, further comprising: washing and drying, specifically comprising : Rinse the composite material after electrodeposition with deionized water, then with absolute ethanol, and then dry naturally. 9. An integrated electrode prepared by the method according to any one of claims 1 to 8, characterized in that it comprises sequential laser welding: Nickel felt: set between the electrode and the diaphragm, it acts as a buffer on the material, avoids the diaphragm from being damaged by impact or friction, and promotes the electrolysis efficiency through the high specific surface area of the nickel felt; Nickel mesh electrode: electrolyze water and generate oxygen or hydrogen on the electrode surface; Nickel mesh flow field: promote the electrolysis reaction, and at the same time form the flow field area of the electrolysis chamber with the main plate on the other side; It also includes a nickel-iron hydroxide deposition layer compounded on the surface of the integrated electrode. 10. An electrolytic cell, characterized in that it comprises the integrated electrode as claimed in claim 9.

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