A method for preparing a nickel-based electrode for electrolytic caustic soda

Abstract

The application discloses a preparation method of an electrolytic alkaline water nickel-based electrode and belongs to the technical fields of electrolytic hydrogen production and material surface engineering. The electrolytic alkaline water nickel-based electrode is prepared by adopting pure nickel as an outer skin of a flux-cored wire, and the inner part is wrapped with 5-20 wt.% aluminum powder and 1-5 wt.% zinc powder. The specific steps include: cleaning and grit blasting the surface of a substrate; preparing an array of welding spots on the pretreated surface of the substrate by adopting a pulsed metal-arc additive process, and the process parameters are as follows: current 100-120 A, voltage 22-23 V, argon flow rate 15 L / min, dry elongation 10-11 mm, welding speed 15-35 mm / s, and pulse frequency 10-50 Hz; and the obtained electrode sample is placed into a mixed solution of potassium hydroxide and potassium sodium tartrate for water bath heating, so that the electrolytic alkaline water nickel-based electrode is obtained. The electrolytic alkaline water nickel-based electrode has high double-layer capacitance and low hydrogen production overpotential, and has good electrocatalytic performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrolytic hydrogen production and material surface engineering, and particularly relates to a preparation method of an electrolytic alkaline water nickel-based electrode. BACKGROUND

[0002] With the increasing global energy demand and the obvious electrification trend, the global energy industry is experiencing the third energy revolution in the direction of low carbonization and low pollution. Hydrogen energy is a secondary energy source with wide sources, clean and carbon-free, flexible and efficient, and rich application scenarios. It can be obtained through various ways and is an ideal interconnection medium for promoting clean and efficient utilization of traditional fossil energy and supporting large-scale development of renewable energy.

[0003] Hydrogen energy is widely used and in great demand. Currently, the electrolytic alkaline water hydrogen production technology is mature, has high energy conversion efficiency, simple process, and broad prospects. However, due to the use of platinum and other noble metal catalysts in the electrode, the cost of the alkaline water electrolysis hydrogen evolution electrode is relatively high, which limits its practical production and large-scale application.

[0004] Nickel-based materials have the dual advantages of relatively low hydrogen evolution overpotential and low cost, and are the first choice for hydrogen evolution materials. Studies have shown that the catalytic performance of the catalyst is closely related to the morphology of the electrolysis electrode surface, the number of active sites, the specific surface area, and other factors. A larger specific surface area provides more contact area between the electrode and the electrolyte, thereby reducing the hydrogen production overpotential of water electrolysis, and increasing the surface area of the electrode can effectively improve the catalytic efficiency of the electrode, that is, a higher electrolysis working current is obtained under the same voltage.

[0005] There are many methods for preparing nickel electrodes at present, including electroplating, chemical plating layer, stamping, and magnetron sputtering. However, the efficiency of synthesizing electrode materials by these methods is very low, the thickness of the prepared electrode is limited, and the cost is high, which cannot meet the large consumption of catalytic materials in large-scale applications. SUMMARY

[0006] In view of the problems existing in the prior art, the application provides a preparation method of an electrolytic alkaline water nickel-based electrode. The electrolytic alkaline water nickel-based electrode prepared by the application has high double-layer capacitance, low hydrogen production overpotential, and good electrocatalytic performance.

[0007] To achieve the above-mentioned purpose, the application provides the following technical solutions:

[0008] An electrolytic alkaline water nickel-based electrode is prepared by using pure nickel (nickel strip) to prepare a flux-cored wire, and the nickel strip outer skin is wrapped with 5-20wt.% aluminum powder and 1-5wt.% zinc powder. The total filling amount of aluminum powder and zinc powder is not higher than 23%.

[0009] Further, the diameter of the flux-cored wire is 1.6mm, and the positive and negative tolerances are within 0.03mm.

[0010] The application also provides a preparation method of the electrolytic alkaline nickel-based electrode, comprising the following steps:

[0011] (1) using pure nickel outer skin to wrap 5-20wt.% aluminum powder and 1-5wt.% zinc powder inside to form a cored wire, and cleaning and grit blasting the surface of the substrate;

[0012] (2) using pulse melting electrode arc additive process to prepare a welding spot on the pretreated surface of the substrate, and the process parameters are as follows: current 100-120A, voltage 22-23V, argon flow rate 15L / min, dry elongation 10-11mm, welding speed 15-35mm / s, and pulse frequency 10-50Hz; the welding gun is arranged on a manipulator or a walking device, and the additive path is reasonably set according to the surface shape of the required electrode to completely cover the required surface one by one;

[0013] (3) placing the obtained electrode sample into a 30wt.% KOH and 10wt.% potassium sodium tartrate solution for water bath heating to remove Al and Zn in the nickel layer obtained by additive to form a micro-porous structure, i.e. to obtain an electrolytic alkaline nickel-based electrode.

[0014] Further, the roughness Ra of the treated substrate surface in step (1) is 2-10μm, and the substrate is a nickel plate.

[0015] Further, in step (3), the water bath heating refers to water bath heating at 70℃ for 24-128h.

[0016] The electrolytic alkaline nickel-based electrode prepared by the preparation method of the application has a potential lower than 0.22V and exhibits excellent electrocatalytic performance.

[0017] The application uses pulse-modulated melting electrode arc additive technology, uses a nickel-based cored wire as the material, and prepares a nickel electrode on a nickel plate, and this technology has high production efficiency and can construct a nickel electrode surface with different scale pores, thus exhibiting excellent electrocatalytic performance.

[0018] Pulse current melting electrode welding has the characteristics of simple process, high efficiency and strong flexibility. It uses a pulse current with a certain frequency and amplitude change to control the melting of the melting electrode (welding wire) to form a droplet, which rhythmically transitions to the molten pool, the base current maintains the stability of the arc, and the base material and the welding wire are preheated, and finally the ideal state of one pulse and one drop is realized, realizing good droplet transition.

[0019] The present application forms the array type welding spots with similar size and same interval on the substrate surface in the way of one pulse and one drop by reasonably controlling the arc input heat, and forms the surface with 2-4 mm high and low relief on the electrode surface.

[0020] Compared with the prior art, the present application has the following advantages and technical effects:

[0021] Compared with the prior art, the present application has the following advantages and technical effects:

[0022] In combination with the post-corrosion treatment, the method of the present application can form the micro-pore structure with different scales in the dot array welding spot, create more active sites, and form higher specific surface area, and through the adjustment of the process parameters and materials, the metal electrode with large specific surface area and excellent catalytic performance can be directly prepared. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which form a part of the present application, are intended to provide further understanding of the present application and serve to explain the present application and its specification, and do not constitute improper limitations to the present application. In the drawings:

[0024] Figure 1 Array welding spots of the nickel electrode for alkaline hydrolysis prepared for Examples 1-3;

[0025] Figure 2 The metallographic cross-section of the nickel electrode for alkaline hydrolysis prepared for Example 3;

[0026] Figure 3 The XRD graph of the nickel electrode for alkaline hydrolysis prepared for Examples 1-3 and Comparative Examples 1-2;

[0027] Figure 4 The LSV curve graph of the nickel electrode for alkaline hydrolysis prepared for Examples 1-3 and Comparative Examples 1-2;

[0028] Figure 5 The Tafel slope curve graph of the nickel electrode for alkaline hydrolysis prepared for Examples 1-3 and Comparative Examples 1-2;

[0029] Figure 6 A plot of double layer capacitance values for the basic hydrolysis nickel electrode prepared for Examples 1-3 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0030] Various exemplary embodiments of the present application will now be described in detail, without intent to limit the application, which is only limited by the claims. Understanding that these embodiments are given only as examples of the application, those skilled in the art will

[0031] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Additionally, the use of "about" in relation to a value or range of values is intended to include each individual intermediate value and each smaller range that falls within the range of values. The upper and lower limits of each smaller range can be independently included or excluded from the range.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described. All publications mentioned in this specification are herein incorporated by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The citation of any reference in this specification is not intended as an admission that the reference is prior art, but rather that the reference is part of the technical literature that is relevant to A person of ordinary skill in the art.

[0033] Many modifications and variations of this application can be made without departing from its spirit or scope, which will be apparent to those skilled in the art. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only. It is to be understood that the application is not limited in scope by the specific embodiments described herein. Those skilled in the art will readily devise their own

[0034] It is to be understood that the terms "including", "comprising", "consisting" and "having" and the like are used interchangeably and are meant to be open-ended terms that do not limit any of the described embodiments to the items recited.

[0035] The present application uses a pulse-modulated fused arc additive technology, uses a nickel-based flux-cored wire as a material, and prepares a nickel electrode on a nickel plate. This technology has high production efficiency and can construct a nickel electrode surface with different scales of pores, thus exhibiting excellent electrocatalytic performance.

[0036] Pulse current electrode welding has the characteristics of simple process, high efficiency and strong flexibility. It is formed by pulse current with certain frequency and amplitude to control the melting of the electrode (welding wire) to form a droplet, which is rhythmically transferred to the molten pool. The base current maintains the stability of the arc and preheats the base material and welding wire. Finally, it realizes the ideal state of one pulse one drop and achieves good droplet transfer.

[0037] The present application forms an array of droplet welding spots with similar size and same spacing on the surface of the substrate by reasonably controlling the arc input heat and in the mode of one pulse one drop, and forms a surface with 2-4 mm high and low relief on the surface of the electrode. At the same time, a small amount of Al and Zn is added by using the mode of flux-cored wire, and the high vapor pressure of Zn promotes the formation of dozens to hundreds of microns of pores in the single welding spot. After welding, overall corrosion is carried out to expose the large pores in the welding spot. At the same time, corrosion can also realize the dealloying of local micro-zone alloying elements to form several microns and microns below the micro-pore. The specific technical scheme is as follows:

[0038] An electrolytic alkaline nickel-based electrode adopts pure nickel outer skin to prepare flux-cored wire, and is wrapped with 5-20wt.% aluminum powder and 1-5wt.% zinc powder inside.

[0039] In the following embodiments of the present application, the diameter of the flux-cored wire is 1.6mm, and the positive and negative tolerances are within 0.03mm.

[0040] The present application also provides a preparation method of the electrolytic alkaline nickel-based electrode, comprising the following steps:

[0041] (1) 5-20wt.% aluminum powder and 1-5wt.% zinc powder are wrapped inside by using pure nickel belt to form flux-cored wire, and the surface of the substrate is cleaned and sandblasted; the surface roughness Ra of the substrate is between 2-10um; the surface roughness Ra is preferably 4-6.8um, more preferably 5.8-6.8um, and most preferably 5.8um, 6.8um. The content of aluminum powder is preferably 5-10wt.%, more preferably 5wt.%; the content of zinc powder is preferably 3wt.%. The substrate is a nickel plate.

[0042] (2) the welding spot is prepared on the pretreated substrate surface by using a pulse melting electrode arc additive process, and the process parameters are as follows: current 100-120 A, voltage 22-23 V, argon flow rate 15 L / min, dry elongation 10-11 mm, welding speed 15-35 mm / s, and pulse frequency 10-50 Hz; the welding gun is arranged on a manipulator or a walking device, the additive path is reasonably set according to the surface contour of the required electrode, and the required surface is completely covered one by one; the current can be preferably 100-120 A, more preferably 110-120 A, and most preferably 110 A or 120 A. The voltage is preferably 22 V or 23 V. The welding speed is preferably 20-25 mm / s, more preferably 20 mm / s or 25 mm / s, and in a preferred embodiment of the present application, the welding speed is preferably 25-25 mm / s. The pulse frequency is preferably 30-50 Hz, more preferably 30 Hz or 50 Hz, and can also be selected as 10 Hz, but the performance of the prepared electrode material is slightly weak.

[0043] (3) the obtained electrode sample is placed in a 30wt.% KOH and 10wt.% potassium sodium tartrate solution, and heated in a 70℃ water bath for 24-128 h to remove Al and Zn in the nickel layer obtained by additive manufacturing, so as to form a micro-porous structure, that is, an alkaline electrolytic nickel-based electrode is obtained. The water bath heating time is preferably 100-120 h, and more preferably 100 h or 120 h.

[0044] The size of the nickel electrode welding spot is 2*2 mm.

[0045] The alkaline electrolytic nickel-based electrode prepared by the preparation method of the present application reaches 10 mA·cm -2 The required potential is only 0.22 V at a current density, and excellent electrocatalytic performance is exhibited.

[0046] The following examples are further illustrations of the technical solutions of the present application.

[0047] Example 1

[0048] A preparation method of an alkaline electrolytic nickel-based electrode, the steps are as follows:

[0049] (1) 5wt.% aluminum powder and 3wt.% zinc powder are wrapped in a nickel strip to form a flux-cored wire with a diameter of 1.6 mm;

[0050] (2) the surface of the nickel plate substrate is cleaned and sandblasted, and sandpaper is used for polishing before sandblasting, the surface roughness Ra is 4 μm, and then alcohol is used for cleaning to remove stains;

[0051] (3) The pulse melting electrode arc additive process is used to prepare the welding spot on the pretreated substrate surface, and the process parameters are as follows: current 100 A, voltage 22 V, argon flow rate 15 L / min, dry elongation 10 mm, welding speed 25 mm / s, and pulse frequency 10 Hz; the welding gun is arranged on the manipulator, the additive path is reasonably set according to the surface contour of the required electrode, and the required surface is completely covered one by one;

[0052] (4) The obtained electrode sample is placed in a 30wt.%KOH and 10wt.% potassium sodium tartrate solution, heated in a 70℃ water bath for 100h, and an electrolytic alkaline nickel-based electrode is obtained.

[0053] Example 2

[0054] A preparation method of an electrolytic alkaline nickel-based electrode, the steps are as follows:

[0055] (1) The 10wt.%aluminum powder and 3wt.%zinc powder are wrapped in the nickel strip to form a flux-cored wire with a diameter of 1.6 mm;

[0056] (2) The surface of the nickel plate substrate is cleaned and sandblasted, sandpaper is used for polishing and then sandblasting, the surface roughness Ra is 5.8μm, and then alcohol is used for cleaning to remove stains;

[0057] (3) The pulse melting electrode arc additive process is used to prepare the welding spot on the pretreated substrate surface, and the process parameters are as follows: current 110 A, voltage 22 V, argon flow rate 15 L / min, dry elongation 10 mm, welding speed 20 mm / s, and pulse frequency 30 Hz; the welding gun is arranged on the manipulator, the additive path is reasonably set according to the surface contour of the required electrode, and the required surface is completely covered one by one;

[0058] (4) The obtained electrode sample is placed in a 30wt.%KOH and 10wt.% potassium sodium tartrate solution, heated in a 70℃ water bath for 120h, and an electrolytic alkaline nickel-based electrode is obtained.

[0059] Example 3

[0060] A preparation method of an electrolytic alkaline nickel-based electrode, the steps are as follows:

[0061] (1) The 5wt.%aluminum powder and 3wt.%zinc powder are wrapped in the nickel strip to form a flux-cored wire with a diameter of 1.6 mm;

[0062] (2) The surface of the nickel plate substrate is cleaned and sandblasted, sandpaper is used for polishing and then sandblasting, the surface roughness Ra is 6.8μm, and then alcohol is used for cleaning to remove stains;

[0063] (3) The welding spot was prepared on the pretreated substrate surface by pulsed metal arc additive process with the process parameters of current 120 A, voltage 23 V, argon flow rate 15 L / min, dry elongation 11 mm, welding speed 25 mm / s, and pulse frequency 50 Hz; the welding gun was arranged on the manipulator, and the additive path was reasonably set according to the surface profile of the required electrode, so as to completely cover the required surface one by one;

[0064] (4) The obtained electrode sample was placed into a 30 wt.% KOH and 10 wt.% potassium sodium tartrate solution, and heated in a 70℃ water bath for 120 h, to obtain a nickel-based electrode for electrolytic alkaline water.

[0065] Comparative Example 1

[0066] The same as Example 1, except that the flux-cored wire comprises 25 wt.% aluminum powder and 10 wt.% zinc powder.

[0067] The electrode prepared by using the present comparative example has a Tafel slope of 88 mV·dec -1 , and a double-layer capacitance value of 0.3 mF·cm -2 . When the current density is 10 mA·cm -2 , the required potential is 0.41 V.

[0068] Comparative Example 2

[0069] The same as Example 1, except that the process parameters for preparing the welding spot are as follows: current 130 A, voltage 25 V, argon flow rate 20 L / min, dry elongation 10 mm, welding speed 40 mm / s, and pulse frequency 30 Hz.

[0070] The electrode prepared by using the present comparative example has a Tafel slope of 87 mV·dec -1 , and a double-layer capacitance value of 0.4 mF·cm -2 . When the current density is 10 mA·cm -2 , the required potential is 0.37 V.

[0071] Performance test:

[0072] 1. The electrodes prepared in Examples 1-3 were subjected to porosity analysis, and the coating porosity was analyzed by using the image method by using ImageJ image analysis software. Five metallographic photos of the cross section of the prepared welding spot were calculated, and the average value was taken. Figure 1 FIG. 1 is a schematic diagram of the array-type welding spot of the electrode prepared in Examples 1-3, Figure 2 FIG. 2 is a metallographic photo of the cross section of the electrode prepared in Example 3, and it can be seen that there are many pores in the interior, and the porosity is 14.3 wt.%.

[0073] 2. The electrodes prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to X-ray diffraction experiments using a D8 ADVANCE X-ray diffractometer. The test conditions were: Cu target Kα radiation, voltage 40 kV, current 50 mA, diffraction angle (2θ) measurement range 10-90°, scanning step 0.02°, and temperature 298 K. Figure 3 For the XRD patterns of the electrodes prepared in Examples 1-3, it can be seen that the main elements in the electrodes are Ni phases, the standard card corresponding to the Ni diffraction peaks is PDF #04-0580, and the characteristic peak positions are 44.5°, 51.8° and 76.4°.

[0074] 3. The electrodes prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to electrochemical tests, Figure 4 The LSV curves at a scanning rate of 5 mV / s -1 are shown in Figure 1. At a current density of 10 mA·cm -2 , the required potentials for Examples 1-3 were 0.27 V, 0.25 V and 0.22 V, and the required potentials for Comparative Examples 1-2 were 0.41 V and 0.37 V. Figure 5 The Tafel slope plots of the electrodes prepared in Examples 1-3 and Comparative Examples 1-2 are shown in Figure 2. The Tafel slopes of Examples 1-3 were 55 mV·dec -1 , 50 mV·dec -1 and 40 mV·dec -1 , respectively, showing excellent electrocatalytic performance, and the Tafel slopes of Comparative Examples 1-2 were 88 mV·dec -1 , 87 mV·dec -1 , respectively.

[0075] 4. The electrodes prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to CV tests, and the double-layer capacitance values were calculated. CV cyclic tests were carried out at a scanning rate of 20 mV / s, 50 mV / s, 100 mV / s, 150 mV / s and 200 mV / s in the potential range of 0.25-0.35 V, and the number of cycles was 40. The double-layer capacitance values of Examples 1-3 were calculated by fitting to be 0.8 mF·cm -2 , 0.9 mF·cm -2 and 1.1 mF·cm -2 , respectively. The double-layer capacitance values of Comparative Examples 1-2 were 0.3 mF·cm -2 and 0.4 mF·cm -2 , respectively, as shown in Figure 3. Figure 6

[0076] ​The above merely provides the preferred embodiments of the present application, and the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for the preparation of an electrolytic caustic nickel-based electrode, characterized in that, The method comprises the following steps: (1) wrapping aluminum powder and zinc powder in a pure nickel outer skin to form a cored wire, and cleaning and grit blasting the substrate; the content of the aluminum powder is 5-20 wt.%, and the content of the zinc powder is 1-5 wt.%; (2) preparing a welding spot on the surface of the pretreated substrate by using a pulsed metal-arc additive process, and the process parameters are as follows: current 100-120 A, voltage 22-23 V, argon flow rate 15 L / min, dry elongation 10-11 mm, welding speed 15-35 mm / s, and pulse frequency 10-50 Hz; the high vapor pressure of Zn promotes the formation of dozens to hundreds of microns of pores in the single welding spot; (3) placing the obtained electrode sample into a mixed solution of potassium hydroxide and potassium sodium tartrate for water bath heating, exposing the macropores in the welding spot, and removing Al and Zn in the additive to form a micro-porous structure, i.e. obtaining a nickel-based electrode in electrolytic alkaline water.

2. The production method according to claim 1, characterized by, The content of the aluminum powder is 5-10 wt.%, and the content of the zinc powder is 3 wt.%.

3. The production method according to claim 1, characterized by, The diameter of the cored wire is 1.6±0.03 mm.

4. The method of claim 1, wherein, The surface roughness Ra of the treated substrate in step (1) is 2-10 μm, and the substrate is a nickel plate.

5. The preparation method according to claim 1, characterized in that, In step (3), the water bath heating refers to water bath heating at 70 °C for 24-128 h.

6. The method of claim 1, wherein, In step (3), the concentration of potassium hydroxide in the mixed solution is 30 wt.%, and the concentration of sodium tartrate is 10 wt.%.

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