Nickel electrode with multi-level structure and preparation method thereof

Abstract

The invention discloses a nickel electrode with a multi-level structure and a preparation method of the nickel electrode. The preparation method comprises the following steps: firstly, cleaning and activating substrate foamed nickel with micron-sized pores to obtain first substrate nickel; performing plasma treatment to form second substrate nickel with uniform nanoscale pits; then carrying out mild oxidation treatment, so that the uniform nickel oxide layer is embedded into the pit; generating a carbon layer on the surface of the oxide layer by using chemical vapor deposition, and constructing a mesoscopic pore channel network; then activating the surface of the sample, introducing a gas production reagent to form an active material layer attached to the carbon layer, and cleaning to obtain the nickel electrode with the multi-level structure; the electrode comprises the second substrate nickel, the oxide layer, the carbon layer and the active material layer, the carbon layer has a nanoscale pore network, the active material layer has a smaller micropore network, the specific surface area, the conductivity and the catalytic activity of the electrode can be improved, and the electrode has a good application prospect. The method can be used for preparing the electrode with a macroscopic-mesoscopic-microscopic transmission network, and the electrode has relatively high specific surface area and active sites.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of electrolytic water catalytic material preparation, and particularly relates to a multi-level structure nickel electrode and a preparation method thereof. BACKGROUND

[0002] With the continuous improvement of people's living standards, the problem of energy shortage is increasingly prominent. Hydrogen, as a renewable energy material with the highest energy density and clean properties, is expected to become the most valuable alternative to fossil fuels, which can solve the problems of sustainability, environmental emissions and energy security, and thus has attracted widespread attention from countries.

[0003] Using electrocatalytic water splitting to convert water into hydrogen is a promising technology to solve the energy crisis; however, under industrial-level high current density, the electrolytic water catalyst has a serious problem of aggregation and falling off, which leads to rapid performance decline, and further affects the structure and performance of the electrode, which seriously restricts the industrialization progress of electrocatalytic water splitting; in addition, in the process of electrolytic water, due to the slow speed of material transport and diffusion, the reactants (such as hydrogen ions or hydroxyl ions) cannot reach the electrode surface in time to participate in the reaction, resulting in a decrease in the concentration of reactants on the electrode surface, that is, the slow material transport and diffusion makes the reactants unable to be replenished in time under high current density, and in order to maintain the reaction rate, the electrode needs a higher potential to drive the reaction, this additional potential is overpotential, the increase of overpotential means that more electrical energy is needed to drive the reaction, thus leading to a decrease in energy efficiency and restricting the industrialization of electrolytic water.

[0004] The existing partial catalytic electrode adopts an organic binder such as Nafion, but the organic binder has low conductivity, which reduces the overall activity and easily causes the electrocatalyst to fall off when oxygen is violently generated on the electrode surface under high current density. SUMMARY

[0005] Therefore, the embodiments of the present disclosure provide a multi-level structure nickel electrode and a preparation method thereof, which can solve one or more of the problems of low energy efficiency, low electrode catalytic activity, low reaction efficiency, and poor long-term stability of the electrode caused by catalyst particle falling off in the prior art.

[0006] In a first aspect, the embodiments of the present disclosure provide a multi-level structure nickel electrode, which specifically comprises:

[0007] A substrate nickel, a surface of the substrate nickel is formed with uniform nanoscale pits, and the substrate nickel has a micrometer-scale pore structure inside;

[0008] An oxidation layer covering the surface of the substrate nickel and embedded in the pits; the oxidation layer is a uniform nickel oxide layer formed on the surface of the substrate nickel,

[0009] A composite transition layer covering the surface of the oxide layer; the composite transition layer includes a carbon layer covering the surface of the oxide layer and an active material layer attached to the surface of the carbon layer.

[0010] Optionally, the porosity of the nickel substrate is 90%-98%, and the average pore size of the nickel substrate is 100 μm-120 μm;

[0011] The thickness of the oxide layer is 50nm-100nm;

[0012] The carbon layer has a pore network of 10nm-100nm;

[0013] The active material layer has a microporous network with a diameter less than 10 nm.

[0014] In a second aspect, the present application discloses a method for preparing a multi-layer nickel electrode, comprising:

[0015] The base nickel foam is subjected to overall cleaning and surface activation treatment to obtain a first base nickel; the base nickel foam has a micron-scale pore structure inside;

[0016] Treating the first nickel substrate with a plasma treatment process to obtain a second nickel substrate having uniform nanoscale pits formed on the surface;

[0017] Performing a mild oxidation treatment on the surface of the second nickel base to form an oxide layer on the surface of the second nickel base; the oxide layer is a uniform nickel oxide layer embedded in the pit;

[0018] Performing chemical vapor deposition on the second nickel substrate after oxidation to generate a carbon layer on the surface of the oxidation layer, and performing a mesoscopic pore network construction process on the carbon layer during the growth of the carbon layer;

[0019] The sample after the mesoscopic pore network construction treatment is subjected to surface activation treatment, and a gas generating reagent is introduced to obtain an active material layer attached to the carbon layer; the treated sample is cleaned to obtain a multi-layer structure nickel electrode;

[0020] The multi-layered nickel electrode includes a second base nickel, an oxide layer covering the surface of the second base nickel, a carbon layer covering the surface of the oxide layer, and an active material layer attached to the surface of the carbon layer. The carbon layer has a nanoscale pore network, and the active material layer has a microporous network with a pore size smaller than the pore size in the pore network.

[0021] The present application discloses a method for preparing a multi-layer nickel electrode. First, a base nickel foam having a micron-scale pore structure is cleaned as a whole and subjected to surface activation treatment to obtain a first base nickel. The surface activation treatment causes more active sites to be generated on the surface of the base nickel foam, thereby enhancing its reactivity with subsequent treatment substances. Second, the first base nickel is treated with a plasma treatment process to obtain a second base nickel with uniform nanoscale pits formed on the surface. The formation of uniform nanoscale pits significantly increases the specific surface area of ​​the base. A larger specific surface area means more active sites, which can increase the contact area between the electrode and the reactant, thereby improving the catalytic activity and reaction of the electrode. Rate. In the electrocatalytic water splitting reaction, more active sites can adsorb more reactant molecules and speed up the reaction process. The nano-scale pits provide more anchoring points for the subsequently formed oxide layer, so that the oxide layer can be more firmly embedded therein. This physical intercalation enhances the bonding force between the oxide layer and the substrate, helps to improve the stability of the electrode structure, and prevents the oxide layer from falling off during use, thereby ensuring the long-term stability of the electrode performance. Third, a mild oxidation treatment is performed on the surface of the second nickel substrate to form an oxide layer on the surface of the second nickel substrate. The oxide layer is a uniform nickel oxide layer embedded in the pits, which can serve as an intermediate medium for electron transmission and improve the electron transport in the The transmission efficiency between the substrate and the subsequent layers is improved, and the oxide layer is embedded in the nano-scale pits, which further enhances the overall structural integrity of the electrode. It is tightly combined with the substrate and the subsequent carbon layer to form a continuous and stable structural system, which helps to maintain the performance stability of the electrode under complex reaction conditions; Fourth, the second substrate nickel after oxidation treatment is subjected to chemical vapor deposition treatment to generate a carbon layer on the surface of the oxide layer, and during the growth of the carbon layer, the carbon layer is subjected to mesoscopic pore network construction treatment; Fifth, the sample after the mesoscopic pore network construction treatment is subjected to surface activation treatment, and a gas-generating reagent is introduced to obtain an active material layer attached to the carbon layer; The treated sample After cleaning, a multi-level structure nickel electrode is obtained, which can not only improve the conductivity, but also provide a good basis for the attachment of the active material layer through the pore structure and surface properties of the carbon layer. The active material can be better dispersed on the surface of the carbon layer and inside the pores, increasing the contact area between the active material and the reactant, and improving the utilization rate of the active material; the gas-generating reagent forms a microporous network inside the active material layer, further increasing the specific surface area of ​​the active material layer, more active sites can adsorb more reactant molecules, and improve the catalytic activity of the electrode. The microporous network is interconnected with the mesoscopic pore network of the carbon layer to form a multi-level pore structure, which optimizes the material transfer path and improves the material transfer efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] Figure 1 A schematic flow chart of a method for preparing a multi-layer nickel electrode provided in an embodiment of the present disclosure.

[0024] Figure 2 A schematic flow chart of a method for obtaining the first nickel substrate provided in an embodiment of the present disclosure.

[0025] Figure 3 A schematic flow chart of a method for obtaining the second nickel substrate provided in an embodiment of the present disclosure.

[0026] Figure 4 A schematic flow chart of a method for generating a carbon layer according to an embodiment of the present disclosure.

[0027] Figure 5 A schematic flow chart of a method for constructing a mesoscopic pore network in a carbon layer provided in an embodiment of the present disclosure.

[0028] Figure 6 A schematic flow chart of a method for obtaining an active material layer according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0029] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0030] Reference Figure 1 The first aspect of the present application discloses a method for preparing a multi-layer nickel electrode, comprising:

[0031] S100, the base nickel foam is cleaned as a whole and subjected to surface activation treatment to obtain a first base nickel; the base nickel foam has a micron-level pore structure inside.

[0032] Specific reference Figure 2 , a method for obtaining a first nickel substrate, comprising:

[0033] S110, placing the nickel foam substrate in acetone, ethanol, and deionized water in sequence and ultrasonically treating the substrate for 15 to 20 minutes, and rapidly drying the treated nickel foam substrate with a nitrogen stream;

[0034] S120, treating the dried nickel foam substrate in a vacuum drying oven at 50° C. to 55° C. for 1.5 to 2 hours to completely remove surface adsorbed water;

[0035] S130, soaking the dried nickel foam substrate in a weak alkaline cleaning agent for 10 to 20 minutes to activate the surface;

[0036] S140, rinsing the soaked base nickel foam with deionized water, and drying with a nitrogen flow to obtain a first base nickel.

[0037] For S110, acetone has good solubility and can effectively dissolve oil, organic impurities, and other impurities on the surface of the base nickel foam. Ethanol can further remove residual acetone and some water-soluble and alcohol-soluble impurities, acting as a transition and further cleaning agent. Deionized water is used to thoroughly rinse away residual cleaning agent, ensuring the purity of the base nickel foam surface. Ultrasonic treatment utilizes the cavitation effect of ultrasound to generate tiny bubbles that quickly burst, generating a powerful impact force, more effectively removing surface impurities and improving the cleaning effect. Nitrogen flow is used for rapid drying. Nitrogen is an inert gas that isolates the air, preventing oxidation of the base nickel foam during the drying process, and maintaining its surface activity and purity. By sequentially using acetone, ethanol, and deionized water for cleaning, followed by vacuum drying and deionized water rinsing, the oil, impurities, and adsorbed water on the base nickel foam surface are completely removed, ensuring the high purity of the first base nickel, facilitating the smooth progress of subsequent processes and improving the performance of the final product.

[0038] For S120, the temperature range of 50℃-55℃ can ensure that the water can evaporate quickly without having an adverse effect on the structure and performance of the base nickel foam due to excessively high temperature; the vacuum environment can prevent oxygen and other gases from contacting the base nickel foam, preventing oxidation, while accelerating the evaporation rate of water, ensuring that the surface adsorbed water is completely removed. The surface of the base nickel foam after drying is drier and cleaner, which is conducive to subsequent activation treatment and other process steps.

[0039] For S130, the weak alkaline cleaning agent can chemically react with some oxides and impurities on the surface of the base nickel foam, remove the passivation layer on the surface, and make the surface more active; at the same time, the weak alkaline environment is relatively mild and will not cause excessive corrosion and damage to the structure of the base nickel foam; the activated surface has more active sites, which is conducive to the subsequent adhesion and reaction of other substances, thereby improving the performance and application effect of the material.

[0040] For S140, deionized water rinsing can remove the residual weak alkaline detergent and other impurities on the surface of the base nickel foam, ensuring the purity of the surface; nitrogen flow is used again to blow dry, also to prevent the base nickel foam from being oxidized during the drying process, maintain its surface activity and purity, and obtain a good quality first base nickel, providing high-quality basic materials for subsequent process steps.

[0041] The process conditions used in the entire treatment process are relatively mild and will not damage the structure of the base nickel foam, ensuring its original characteristics such as the micron-level pore structure inside, which is conducive to the development of its unique physical and chemical properties.

[0042] After executing S100, execute S200, as follows:

[0043] S200 , treating the first nickel base with a plasma treatment process to obtain a second nickel base with uniform nano-scale pits formed on the surface.

[0044] Specific reference Figure 3 , a method for obtaining the second nickel substrate comprises:

[0045] S210, placing the first nickel substrate in a plasma reaction chamber, and evacuating the chamber to a basic vacuum degree of 0.5 Pa-1.5 Pa.

[0046] Specifically, the plasma reaction chamber is opened, and the first nickel substrate is carefully placed in a suitable position inside the reaction chamber; after closing the reaction chamber, the vacuum pump is started to evacuate the reaction chamber; the vacuum degree in the reaction chamber is monitored in real time by a vacuum gauge, and the vacuum operation is stopped when the vacuum degree preferably reaches 1 Pa. Evacuating to a lower basic vacuum degree can remove impurity gases in the reaction chamber, such as oxygen and water vapor, which may interfere with the subsequent plasma treatment process and affect the treatment effect. For example, oxygen may react with active particles in the plasma, changing the composition and properties of the plasma. The lower basic vacuum degree creates a pure environment for the subsequent introduction of specific mixed gases and plasma treatment, ensuring the stability and repeatability of the treatment process.

[0047] S220, introduce Ar / O2 mixed gas, and adjust the working vacuum of the plasma reaction chamber to 45Pa-55Pa, and control the gas flow rate to 45sccm-55sccm; among them, the volume proportion of Ar is 75%-85%, and the volume proportion of O2 is 15%-25%.

[0048] Specifically, prepare Ar and O2 gas cylinders, and accurately control the flow of the two gases through a gas flow controller so that the volume proportion of Ar is 80% and the volume proportion of O2 is 20%. Open the gas valve and introduce the mixed gas into the plasma reaction chamber; at the same time, observe the readings of the vacuum gauge and the gas flow controller, and stabilize the working vacuum degree of the reaction chamber at 50Pa and the gas flow rate at 50sccm by adjusting the air inlet valve and the vacuum pump's exhaust rate.

[0049] Ar is an inert gas that can be used as a carrier gas and the main gas for generating plasma in plasma. Ar ions have high energy under the action of an electric field and can bombard the surface of the first substrate nickel, thereby etching it. The addition of O2 can chemically react with the surface of the substrate nickel to form oxides. At the same time, O2 plasma also has certain etching and activation effects. A suitable Ar / O2 ratio (such as 80% Ar+20% O2) can achieve a balance between etching and oxidation, which is conducive to the formation of uniform nano-scale pits. Controlling the working vacuum and gas flow rate can ensure the stability and uniformity of the plasma. Suitable working vacuum and gas flow rate can make the active particles in the plasma evenly distributed, thereby achieving a uniform treatment effect on the surface of the first substrate nickel.

[0050] The preferred ratio of the Ar / O2 mixed gas is 80% Ar and 20% O2.

[0051] S230, set the plasma power to 90W-110W, use pulse mode for treatment, maintain the temperature at 23℃-27℃ during the treatment process, and the total treatment time is 4.5 minutes-5.5 minutes; among them, the pulse on time is 1.8s-2.2s, and the off time is 0.8s-1.2s.

[0052] Specifically, through the control panel of the plasma generator, the plasma power is preferably set to 100W, the pulse mode is selected, and the pulse on time is preferably set to 2s, and the off time is preferably set to 1s; the temperature in the reaction chamber is monitored in real time by a temperature sensor, and the temperature is preferably maintained at 25°C by a cooling system (such as circulating water cooling), the plasma generator is started, and the treatment is started, and the total treatment time is preferably set to 5 minutes. Suitable plasma power (such as 100W) can provide sufficient energy to generate plasma and make the active particles in the plasma have suitable energy and density, thereby achieving effective etching and treatment of the nickel surface of the first substrate.

[0053] Using a pulse mode (such as an on time of 2s and an off time of 1s) can prevent overheating of the sample surface; when the pulse is on, the plasma treats the surface of the base nickel; when the pulse is off, the sample surface has time to dissipate heat, preventing changes in the sample surface structure due to continuous heating, thereby ensuring the formation quality of nano-scale pits and the original structure of the base nickel; maintaining the treatment temperature within the range of 23°C-27°C can provide a relatively stable treatment environment, avoid the effects of excessively high or low temperatures on the properties and treatment effects of the plasma, and facilitate the formation of uniform and regular nano-scale pits.

[0054] S240, after the treatment is completed, the treated first nickel base is quickly taken out and placed in an inert gas environment to obtain a second nickel base; uniform nano-scale pits are formed on the surface of the second nickel base.

[0055] Specifically, when the treatment time reaches 5 minutes, the plasma generator and gas valve are immediately turned off, the reaction chamber is opened, and the treated first base nickel is quickly taken out with tweezers and placed in a glove box filled with nitrogen to prevent it from reacting with oxygen, water vapor, etc. in the air. Rapidly taking out the treated first base nickel and placing it in an inert gas environment can prevent the treated surface from being oxidized or contaminated. Uniform nano-scale pits are formed on the treated surface. These pits have high surface activity and are easy to react with substances in the air. The inert gas environment (such as nitrogen) can provide a protective barrier to maintain the stability and cleanliness of the nano-scale pits, thereby ensuring the performance and quality of the second base nickel.

[0056] Plasma treatment, as a milder and more controllable surface activation method, can effectively replace the mixed acid etching process. Nickel foam treated in this way forms uniform nanoscale pits on its surface, significantly increasing the density of its surface active sites while maintaining good electrical conductivity. Compared with mixed acid etching, plasma treatment offers advantages such as precise control of process parameters, more uniform surface modification, minimal damage to the substrate, environmental friendliness, and no waste liquid disposal issues, making it particularly suitable for industrial large-scale production. The surface of the nickel foam treated with plasma not only has an appropriate roughness and abundant active sites, but also maintains good electrical conductivity, providing an ideal substrate for the subsequent growth of active materials.

[0057] The plasma treatment method disclosed in S210-S240 can form uniform nano-scale pits on the surface of the first base nickel. These nano-scale pits can significantly increase the specific surface area of ​​the material and improve the contact area between the material and other substances, thereby having potential application value in electrochemistry, catalysis and other fields; for example, in the field of electrochemistry, a larger specific surface area can increase the contact area between the electrode and the electrolyte, increase the reaction activity and charge and discharge efficiency of the electrode; the use of pulse mode and temperature control and other measures can avoid structural changes caused by overheating of the sample surface, thereby ensuring the original structure and performance of the base nickel, which makes the second base nickel have better stability and reliability in subsequent processing and application.

[0058] Throughout the entire process, precise control is exercised over parameters such as base vacuum, operating vacuum, gas flow rate, plasma power, pulse mode, treatment temperature, and time, ensuring excellent repeatability and controllability. These parameters can be adjusted to precisely control the size, density, and distribution of the nanoscale pits, meeting the requirements of diverse application scenarios. During the treatment process, the plasma's etching and oxidation actions not only form the nanoscale pits but also clean and activate the surface of the primary nickel substrate, removing impurities and oxide layers. This results in a more active surface, facilitating subsequent bonding and reaction with other materials and providing a foundation for further functionalization.

[0059] After executing S200, execute S300, as follows:

[0060] S300, performing mild oxidation treatment on the surface of the second nickel base to form an oxide layer on the surface of the second nickel base; the oxide layer is a uniform nickel oxide layer embedded in the pits.

[0061] Specifically, the method for forming the oxide layer includes placing the second nickel substrate in a tube furnace and heat-treating it at 280°C to 320°C (preferably 300°C) in a nitrogen atmosphere containing oxygen for 0.9 to 1.1 hours (preferably 1 hour), with the heating rate controlled at 4.5°C / min to 5.5°C / min (preferably 5°C / min). Such mild oxidation conditions ensure the formation of an oxide layer of uniform thickness without over-oxidation that affects the conductivity of the substrate.

[0062] The volume proportion of oxygen in the mixed gas is 4%-6% (preferably 5%); the thickness of the oxide layer is 50nm-100nm.

[0063] In this embodiment, the oxide layer is a thin and dense nickel oxide layer. The nickel oxide layer acts as a barrier that effectively prevents oxygen, moisture, and other corrosive substances in the external environment from further contacting the nickel substrate. This helps prevent the nickel substrate from being over-oxidized and corroded, thereby extending the service life of the substrate material and maintaining the stability and reliability of the material. The thin and dense nickel oxide layer can make the chemical properties of the nickel substrate surface more stable. Nickel oxide has a relatively stable crystal structure that can reduce the activity of surface atoms and reduce the possibility of chemical reactions occurring on the surface. For example, in a catalytic reaction, if the surface of the nickel substrate is too active, it may lead to the occurrence of side reactions, and the presence of the nickel oxide layer can inhibit this situation and improve the selectivity and efficiency of the reaction. The formation of the nickel oxide layer can change the hydrophilicity and hydrophobicity of the nickel substrate surface. According to actual needs, by adjusting the properties of the nickel oxide layer, the surface can be made more hydrophilic or hydrophobic. In some applications that require liquid-solid interface reactions, the appropriate hydrophilicity and hydrophobicity can promote the adsorption and reaction of reactants on the surface, thereby improving the reaction rate and efficiency.

[0064] The nickel oxide layer formed by mild oxidation has a uniform thickness within an appropriate range (50nm-100nm), which not only ensures the conductivity of the base nickel to a certain extent, but also utilizes the semiconductor properties of nickel oxide to achieve some special electrical functions. The uniform nickel oxide layer can make the electrical properties of the base nickel surface more uniform and stable. Compared with unoxidized or over-oxidized surfaces, this thin and dense oxide layer can reduce fluctuations in surface resistance and reduce electrical noise.

[0065] After executing S300, execute S400 as follows:

[0066] S400, performing chemical vapor deposition on the second nickel substrate after oxidation treatment to generate a carbon layer on the surface of the oxidation layer, and performing mesoscopic pore network construction on the carbon layer during the growth of the carbon layer.

[0067] Reference Figure 4 The method of "performing a chemical vapor deposition treatment on the second nickel substrate after oxidation treatment to form a carbon layer on the surface of the oxide layer" in S400, i.e., the method of forming the carbon layer, includes:

[0068] S411, placing the second nickel substrate after oxidation treatment in a chemical vapor deposition furnace and heating it to 680°C-720°C.

[0069] This stage is mainly to complete the deposition of the carbon layer.

[0070] S412, introducing acetylene gas as a carbon source, the acetylene gas flow rate is 45 sccm-55 sccm, and the reaction time is controlled at 28 minutes-32 minutes.

[0071] During the S412 process, carbon atoms produced by the decomposition of acetylene gas will deposit on the surface of the oxide layer to form a carbon layer. Acetylene decomposes to produce carbon atoms within the temperature range of 680°C to 720°C. This temperature ensures that the acetylene has sufficient energy to decompose into active carbon atoms, but does not exceed the temperature, causing the carbon atoms to overreact or form an unstable carbon structure. At this temperature, the decomposed carbon atoms can smoothly deposit on the surface of the oxide layer and bond well with the substrate, forming a continuous and uniform carbon layer. If the temperature is too high, it may damage the nickel substrate and affect the bonding quality of the carbon layer to the substrate. If the temperature is too low, the acetylene will not decompose fully, making it difficult to form a complete carbon layer.

[0072] S413, after cutting off the carbon source gas, naturally cooling to room temperature under nitrogen protection, forming a carbon layer on the surface of the oxide layer.

[0073] Specifically, after cutting off the carbon source gas, nitrogen is introduced into the furnace cavity at a certain flow rate (for example, 100 sccm) through a gas flow controller to fill the furnace cavity with nitrogen. Turn off the heating system of the furnace body and allow the furnace cavity to cool naturally to room temperature under the protection of nitrogen. After cooling is completed, open the furnace cavity and take out the sample. At this time, a carbon layer has been generated on the surface of the oxide layer. After cutting off the carbon source gas, introducing nitrogen can provide an inert gas environment to prevent the carbon layer and the oxide layer from being oxidized by oxygen in the air during the cooling process. Nitrogen can isolate oxygen, protect the structure and performance of the carbon layer, and ensure the stability of the quality of the generated carbon layer; natural cooling can avoid the generation of large thermal stress inside the carbon layer and the oxide layer due to rapid cooling, thereby preventing the carbon layer from cracking, falling off, or separating from the oxide layer, and ensuring good bonding between the carbon layer and the oxide layer and the integrity of the carbon layer.

[0074] The carbon layer generation method disclosed in S411-S413 generates a carbon layer on the surface of the oxide layer of the second nickel substrate after oxidation treatment, which can significantly improve the performance of the material. The carbon layer has good electrical conductivity, chemical stability and mechanical properties, and can improve the material's electronic conductivity, corrosion resistance and wear resistance. The generated carbon layer provides a good foundation for subsequent functionalization. By constructing a mesoscopic pore network during the carbon layer growth process, the microstructure and surface properties of the carbon layer can be further adjusted, giving the material more functions, such as improving the material's adsorption performance and catalytic activity. The chemical vapor deposition method can uniformly deposit the carbon layer on the surface of the oxide layer, and has good bonding strength with the oxide layer. This method can well adapt to the surface characteristics of the second nickel substrate after oxidation treatment, ensure the compatibility between the carbon layer and the substrate material, and promote the overall performance of the material. By controlling parameters such as temperature, gas flow rate and reaction time, the thickness, structure and performance of the carbon layer can be precisely controlled, which makes the method highly controllable and flexible. Carbon layers with different characteristics can be prepared according to different application requirements to meet diverse application scenarios.

[0075] Reference Figure 5 The method of "constructing a mesoscopic pore network in the carbon layer during the growth of the carbon layer" in S400, i.e., the method of constructing a mesoscopic pore network in the carbon layer, includes:

[0076] S421, before cutting off the carbon source gas and when introducing acetylene gas as the carbon source, adding polyvinyl pyrrolidone as a template agent, the molecular weight of polyvinyl pyrrolidone ranges from 35000 to 45000, and the concentration ranges from 4.5 mg / mL to 5.5 mg / mL.

[0077] The molecular weight of polyvinyl pyrrolidone is preferably 40,000, and the concentration range is preferably 5 mg / mL.

[0078] S422, after naturally cooling to room temperature under nitrogen protection, the sample with a carbon layer is heat treated at 820°C-880°C to completely decompose the polyvinyl pyrrolidone and form a mesoscopic pore network in the carbon layer. The pore size range of the mesoscopic pore network is 10nm-100nm.

[0079] Among them, the heat treatment temperature is preferably 850°C. The high temperature of heat treatment provides sufficient energy for the complete decomposition of PVP. PVP molecules will undergo a pyrolysis reaction at this temperature, their chemical bonds will break, and they will decompose into small molecular gases (such as carbon dioxide, water, nitrogen, etc.) and evaporate. As PVP decomposes, the space originally occupied by it will be vacated, thereby forming mesoscopic channels in the carbon layer.

[0080] High-temperature heat treatment can also optimize the structure of the carbon layer. At high temperatures, the carbon atoms in the carbon layer are highly active and will undergo a certain degree of rearrangement and recrystallization. This rearrangement process helps to eliminate defects in the carbon layer, making the structure of the mesoscopic pores more regular and stable, and improving the connectivity and uniformity of the pores.

[0081] This method precisely controls the size, density, and distribution of mesoscopic pores by controlling parameters such as the molecular weight and concentration of PVP and the heat treatment temperature. Furthermore, this method is highly compatible with the previous carbon layer deposition process, effectively building a mesoscopic pore network without affecting the overall performance of the carbon layer, ensuring a synergistic improvement in the overall material performance.

[0082] First, the carbon layer is deposited at a lower temperature (680℃-720℃) to ensure the quality of the carbon layer and its bonding with the substrate; then the sample with the deposited carbon layer is taken out and placed in a high-temperature furnace for heat treatment at 820℃-880℃ to achieve the formation of mesoscopic channels and structural optimization.

[0083] In addition, the method for preparing a multi-layered nickel electrode disclosed in the present application also includes: introducing a nitrogen-containing precursor (such as pyridine or ammonia) during the chemical vapor deposition process so that the carbon layer formed contains nitrogen doping. These nitrogen atoms can serve as active centers to promote the growth of subsequent catalyst layers.

[0084] Specifically, nitrogen atoms have more outer electrons than carbon atoms. After nitrogen doping in the carbon layer, the nitrogen atoms will exist as active centers. These active centers have higher chemical activity and can produce stronger interactions with atoms or molecules in the catalyst layer to be grown subsequently, such as chemical bonding or adsorption. Nitrogen doping can provide certain support and stability for the structure of the carbon layer. The presence of nitrogen atoms can fill defects and gaps in the carbon layer, reduce structural disorder, and improve the crystallinity and structural stability of the carbon layer. This helps prevent the carbon layer from structural collapse or deformation during the charge and discharge process, ensuring the long-term stability of the electrode performance.

[0085] After executing S400, execute S500 as follows:

[0086] S500, performing surface activation treatment on the sample after the mesoscopic pore network construction treatment, and introducing a gas-generating reagent to obtain an active material layer attached to the carbon layer; cleaning the treated sample to obtain a multi-layer structure nickel electrode.

[0087] Among them, the multi-layer structure nickel electrode includes a second base nickel with uniform nano-scale pits formed on the surface, an oxide layer covering the surface of the second base nickel, a carbon layer covering the surface of the oxide layer, and an active material layer attached to the surface of the carbon layer. The carbon layer has a nano-scale pore network, and the active material layer has a microporous network with a pore size smaller than the pore size in the pore network.

[0088] Reference Figure 6 , a method for obtaining an active material layer, comprising:

[0089] S510 , immersing the treated sample including the carbon layer in a nitric acid solution for 9 minutes to 11 minutes for surface activation treatment to form an active material layer.

[0090] This step can introduce oxygen-containing functional groups such as carboxyl and hydroxyl groups on the surface of the carbon layer.

[0091] S520, placing the treated sample into a mixed solution of a first solution and a second solution containing 0.09g-0.11g of carbamic acid, soaking it at 20℃-25℃ for 18 hours-22 hours, then heating it to 75℃-85℃ and maintaining it for 3 hours-5 hours, so that the carbamic acid decomposes to generate gas to form microscopic channels inside the active material layer.

[0092] Among them, the pore diameter of the microscopic channel is less than 10nm.

[0093] The first solution is 1.4g-1.6g Ni(NO3)2·6H2O dissolved in 22mL-26mL of isopropanol, and the second solution is 0.35g-0.45g Fe(SO4)2·7H2O dissolved in 7mL-9mL of deionized water.

[0094] At the microscopic level, microscopic channels are formed inside the catalyst layer. The entire process can ensure that the formed micropores are evenly distributed and interconnected by precisely controlling the gas generation rate (controlled by the temperature gradient). These microscopic channels are like capillaries in a city, which can ensure that the reactants directly contact the catalytic active sites. That is, the formation of a microporous network formed by the microscopic channels further increases the specific surface area of ​​the active material layer, provides more active sites, and is beneficial to improving the capacitance performance and catalytic activity of the electrode.

[0095] The mixed solution contains Ni(NO3)2·6H2O and Fe(SO4)2·7H2O. During the immersion and reaction process, nickel ions and iron ions participate in the formation of the active material layer. Nickel and iron elements have different chemical properties and catalytic activities. By controlling their ratio and reaction conditions, the composition and structure of the active material layer can be regulated, thereby optimizing the performance of the electrode. For example, composite oxides or hydroxides of nickel and iron may have better catalytic activity and stability than single metal compounds, making them suitable for different electrochemical reaction systems. The entire process is carried out under relatively mild temperature conditions. The room temperature immersion and the reaction temperature of 75°C-85°C are easy to control, with low equipment requirements. At the same time, the adverse effects of high temperature on the electrode structure and performance are avoided, ensuring the integrity of the electrode structure and the stability of its performance.

[0096] In this embodiment, deionized water is preferably used to wash the treated sample to obtain a multi-layered nickel electrode.

[0097] The multi-layered nickel electrode constructed through the above steps includes a composite transition layer structure, which can provide abundant binding sites, form a good electron transmission channel, and lay the foundation for the construction of a high-performance catalytic electrode.

[0098] Furthermore, before performing S300 to perform mild oxidation treatment on the surface of the second nickel substrate, the method further includes: constructing a graphene conductive network layer on the surface of the second nickel substrate.

[0099] The specific construction method includes: 1) preparing high-quality graphene by a water / organic solvent exfoliation method; further, adding 4.5g-5.5g of graphite powder to 180mL-220mL of N-methylpyrrolidone (NMP), ultrasonically treating for 5.5 hours to 6.5 hours, with an ultrasonic power of 280W-320W, using an intermittent mode, working for 1.8 minutes to 2.2 minutes, and pausing for 0.8 minutes to 1.2 minutes; then centrifuging at a speed of 2800rpm-3200rpm for 28 minutes to 32 minutes, and collecting the supernatant to obtain a graphene dispersion.

[0100] 2) Immersing the plasma-treated nickel foam in a graphene dispersion, and using an ultrasonic-assisted impregnation method, ultrasonicating for 13 minutes to 17 minutes at an ultrasonic frequency of 38 kHz to 42 kHz, to promote uniform adhesion of graphene to the surface of the nickel foam.

[0101] 3) low-temperature vacuum drying is performed at a drying temperature of 38° C. to 42° C., a vacuum degree of -0.075 MPa to -0.085 MPa, and a drying time of 3.5 hours to 4.5 hours, so that the graphene forms a preliminary conductive network, that is, a graphene conductive network layer is constructed on the surface of the second nickel substrate.

[0102] After this step is completed, S300 is performed to perform a mild oxidation treatment on the surface of the second nickel substrate and a subsequent carbon layer is constructed to form a composite transition layer.

[0103] During the multi-level pore construction phase, the properties of graphene were utilized to further optimize the pore structure. In the mesoscopic channel design, a mixture of PVP and reduced graphene oxide (rGO) (3:1 by mass) was used as a template to form a more stable "house of cards" structure. During high-temperature treatment, the rGO sheets spontaneously formed a wrinkled structure, creating additional mass transfer channels. Furthermore, graphene's excellent mechanical properties enhanced the structural stability of the entire electrode, reducing structural deformation and catalyst shedding at high current densities.

[0104] During the catalyst layer growth process, the presence of graphene provides abundant defect sites and oxygen-containing functional groups, which serve as catalyst nucleation centers, promoting the formation of a uniform and dense catalytic layer. The treated sample was placed in a mixture of Liquid A and Liquid B containing an appropriate amount of graphene quantum dots (diameter approximately 3-5 nm, concentration 0.5 mg / mL) for 24 hours at room temperature, followed by a heat treatment at 80°C for 4 hours. The introduction of graphene quantum dots not only enhances the conductivity within the catalyst layer but also provides additional catalytically active sites through quantum size effects.

[0105] In this way, graphene technology is organically integrated with multi-level structural design and multi-level pore construction to form a complete technical solution, which effectively solves multiple technical problems such as conductivity, interface bonding and mass transfer, and provides a systematic solution for the preparation of high-performance industrial-grade water electrolysis electrodes.

[0106] In this embodiment, the prepared multi-layer structure nickel electrode has a macro-meso-micro transmission network, that is, a multi-level pore structure; wherein, macro refers to the micron-scale pore structure, meso refers to the 10nm-100nm pore network, and micro refers to the microporous network less than 10nm. Macro pores are like the main roads in a city, which can ensure the rapid transmission of reactants and products and significantly reduce the mass transfer resistance; mesoscopic pores can connect macro pores and micro pores to form a complete transmission network. These mesoscopic channels are like secondary roads in a city, providing more optional paths for material transmission; micro pores are like capillaries in a city, which can ensure that reactants directly contact the catalytic active sites.

[0107] Specifically, the degree of interconnection between the three-scale pores can be optimized by adjusting parameters such as temperature and pressure during the preparation process. This multi-level pore structure can not only provide abundant mass transfer channels, but also significantly increase the specific surface area of ​​the electrode.

[0108] The present application discloses a method for preparing a multi-layer nickel electrode. First, a base nickel foam having a micron-scale pore structure is subjected to overall cleaning and surface activation treatment to obtain a first base nickel. The surface activation treatment causes more active sites to be generated on the surface of the base nickel foam, thereby enhancing its reactivity with subsequent treatment substances. Second, a plasma treatment process is used to treat the first base nickel to obtain a second base nickel having uniform nanoscale pits formed on the surface. The formation of uniform nanoscale pits significantly increases the specific surface area of ​​the base. A larger specific surface area means more active sites, which can increase the contact area between the electrode and the reactant, thereby improving the catalytic activity and reaction rate of the electrode. The nanometer-scale pits provide more anchoring points for the subsequently formed oxide layer, allowing the oxide layer to be more firmly embedded therein. This physical intercalation enhances the bonding force between the oxide layer and the substrate, helps to improve the stability of the electrode structure, and prevents the oxide layer from falling off during use, thereby ensuring the long-term stability of the electrode performance. Thirdly, a mild oxidation treatment is performed on the surface of the second nickel substrate to form an oxide layer on the surface of the second nickel substrate. The oxide layer is a uniform nickel oxide layer embedded in the pits, which can serve as an intermediate medium for electron transmission and improve the electron transfer between the substrate and the nickel substrate. The transfer efficiency between the substrate and the subsequent layers is improved, and the oxide layer is embedded in the nano-scale pits, which further enhances the overall structural integrity of the electrode. It is tightly combined with the substrate and the subsequent carbon layer to form a continuous and stable structural system, which helps to maintain the performance stability of the electrode under complex reaction conditions; Fourth, the second substrate nickel after oxidation treatment is subjected to chemical vapor deposition treatment to generate a carbon layer on the surface of the oxide layer, and during the growth of the carbon layer, the carbon layer is subjected to mesoscopic pore network construction treatment; Fifth, the sample after the mesoscopic pore network construction treatment is subjected to surface activation treatment, and a gas-generating reagent is introduced to obtain an active material layer attached to the carbon layer; The treated sample is subjected to The multi-layer nickel electrode is cleaned and obtained, which can not only improve the conductivity, but also provide a good basis for the attachment of the active material layer through the pore structure and surface properties of the carbon layer. The active material can be better dispersed on the surface of the carbon layer and inside the pores, increasing the contact area between the active material and the reactant and improving the utilization rate of the active material; the gas-generating reagent forms a microporous network inside the active material layer, further increasing the specific surface area of ​​the active material layer, more active sites can adsorb more reactant molecules, and improve the catalytic activity of the electrode. The microporous network is interconnected with the mesoscopic pore network of the carbon layer to form a multi-level pore structure, which optimizes the material transfer path and improves the material transfer efficiency.

[0109] The self-supporting electrodes proposed in the prior art, on the one hand, have the problem of complicated preparation steps involved and the inability to ensure uniform loading of the active material. On the other hand, there are large differences in the interfacial compatibility between the active material and the carrier, and the stability and activity reduction caused by the insufficient bonding between the active material and the carrier. That is, the self-supporting catalytic electrode preparation method disclosed in the prior art cannot effectively solve the serious agglomeration and shedding problems of the catalyst under high current density, and the experimental scheme is complex, with poor repeatability and controllability, making it unsuitable for industrially rough large-area electrode preparation. At the same time, in the prior art, under industrial-grade high current density, the electrolytic water catalyst has serious agglomeration and shedding problems, resulting in a rapid decline in electrode performance.

[0110] The present application first performs overall cleaning and surface activation treatment on the base nickel foam to obtain a first base nickel, and then uses a plasma treatment process to form uniform nanoscale pits on its surface to obtain a second base nickel. These nanoscale pits increase the specific surface area and roughness of the base, providing more contact points and anchoring sites for the attachment of subsequent layers; then a uniform nickel oxide layer is formed on the surface of the second base nickel and embedded in the pits. The oxide layer is tightly bonded to the base, further enhancing the stability of the structure. The subsequently grown carbon layer and active material layer can better adhere to the oxide layer and are not easy to fall off.

[0111] The multi-layered nickel electrode consists of a second base nickel, an oxide layer, a carbon layer and an active material layer. This multi-layered structure cooperates with each other to form a stable whole. The layers are tightly combined through physical and chemical interactions, so that the active material layer can be firmly attached to the surface of the carbon layer, avoiding the agglomeration and shedding of the catalyst under high current density, thereby ensuring the stability of the electrode structure and performance and extending the service life of the electrode.

[0112] During the chemical vapor deposition process, the carbon layer is subjected to a mesoscopic pore network construction process, so that the carbon layer has a nanoscale pore network. These pore networks provide channels for rapid transmission of reactants (such as hydrogen ions or hydroxide ions), greatly improving the transmission and diffusion speed of substances. The reactants can reach the electrode surface more promptly to participate in the reaction, reducing the decrease in the concentration of reactants on the electrode surface, thereby reducing the overpotential.

[0113] The active material layer has a microporous network with a pore size smaller than that in the pore network of the carbon layer. The microporous network further increases the specific surface area of ​​the active material layer, provides more active sites, and is conducive to the adsorption and reaction of reactants; at the same time, the microporous network and the pore network of the carbon layer are interconnected to form a multi-level pore structure, which further optimizes the material transfer path and improves the material transfer efficiency, thereby reducing the overpotential and improving energy efficiency.

[0114] Some existing catalytic electrodes use organic binders such as Nafion, which have problems such as low conductivity, reduced overall activity, and easy detachment of the electrocatalyst when oxygen evolution on the electrode surface is intense at high current density. The present application uses a multi-layer structure design and preparation process to naturally combine the layers without the use of organic binders. This avoids the negative effects of organic binders, improves the conductivity and overall activity of the electrode, and ensures the stability of the electrode at high current density. At the same time, the nano-scale pits in the multi-layer structure, the pore network of the carbon layer, and the microporous network of the active material layer work together to greatly increase the specific surface area of ​​the electrode. A larger specific surface area means more active sites, which can increase the contact area between the electrode and the reactants, thereby improving the catalytic activity and reaction rate of the electrode. The design of the multi-layer structure allows the advantages of each layer of material to be fully utilized. The oxide layer can improve the chemical stability of the substrate, the carbon layer has good conductivity, and the active material layer provides catalytic activity. The layers work together to optimize the overall performance of the electrode, so that it exhibits better catalytic activity, stability, and energy efficiency in the water electrolysis reaction.

[0115] In this embodiment, the working principle of the prepared multi-layer structure nickel electrode in the process of water electrolysis involves the synergistic effect of multiple levels, which can effectively solve the problem of slow material transfer and diffusion. The specific working process is as follows: 1) The basic characteristics of each level of the electrode provide support for water electrolysis, wherein the second base nickel serves as the basic support structure of the entire electrode. The internal micron-scale pore structure not only increases the specific surface area of ​​the electrode, but also provides an initial channel for the penetration of the electrolyte and material transfer. At the same time, it has good electrical conductivity and can efficiently conduct electrons from the external power supply to the entire electrode system; the uniform nickel oxide layer is embedded in the nano-scale pits of the second base nickel, which on the one hand enhances the bonding force with the substrate and maintains On the one hand, it can ensure the stability of the electrode structure; on the other hand, it can regulate the electronic structure of the electrode surface, promote the transfer of electrons between the substrate and the subsequent carbon layer, and reduce the resistance; the carbon layer has a nanoscale pore network, which greatly increases the specific surface area of ​​the electrode and provides a larger attachment area for the active material layer. Moreover, the good conductivity of the carbon layer itself contributes to the rapid conduction of electrons, and its pore network also provides a fast channel for the transfer of reactants and products; the active material layer contains a microporous network with a pore size smaller than that of the carbon layer pore network, which further increases the specific surface area of ​​the electrode and provides a large number of active sites for water electrolysis reaction. These micropores can enrich the reactants and increase the concentration of the reactants near the active sites.

[0116] 2) During the water electrolysis process, each level synergistically promotes the reaction.

[0117] During the material transfer stage, that is, at the beginning of water electrolysis, the reactants in the electrolyte (hydrogen ions or hydroxide ions) first diffuse into the interior of the electrode through the micron-sized pores of the second nickel substrate. Then, with the help of the nanoscale pore network of the carbon layer, the reactants can be transported more quickly to the electrode surface and the active material layer; the microporous network of the active material layer further enriches and screens the reactants, allowing the reactants to reach the active sites accurately, solving the problem of reactants in traditional electrodes being unable to reach the electrode surface in time, and increasing the concentration of reactants on the electrode surface.

[0118] During the reaction stage, the reactants undergo water electrolysis at the active sites of the active material layer. For the hydrogen evolution reaction (HER), hydrogen ions gain electrons at the active sites and are reduced to hydrogen; for the oxygen evolution reaction (OER), hydroxide ions lose electrons at the active sites and are oxidized to oxygen. The good conductivity of the oxide layer and the carbon layer ensures that electrons can be quickly transferred from the external power source to the active sites, providing sufficient electron supply for the reaction and maintaining its efficient progress.

[0119] During the product discharge stage, the hydrogen and oxygen generated by the reaction are discharged from the electrode as products through the microporous network of the active material layer, the nanoscale pore network of the carbon layer, and the micron-scale pores of the second base nickel. This multi-level pore structure provides a smooth channel for the discharge of products, avoids the accumulation of products on the electrode surface, and reduces obstacles to the reaction.

[0120] In summary, the multi-layered nickel electrode effectively promotes the transport of reactants and the discharge of products through its unique multi-level pore structure and the synergistic effect of each level, increases the concentration of reactants on the electrode surface, and thus improves the efficiency and performance of water electrolysis.

[0121] The second aspect of the present application discloses a multi-layered nickel electrode, which is prepared using the method for preparing the multi-layered nickel electrode disclosed in the first aspect of the present application, and specifically comprises:

[0122] A nickel substrate, wherein the surface of the nickel substrate is formed with uniform nano-scale pits and the interior of the nickel substrate has a micron-scale pore structure;

[0123] The oxide layer covers the surface of the nickel substrate; the oxide layer is a uniform nickel oxide layer formed on the surface of the nickel substrate;

[0124] A composite transition layer covering the surface of the oxide layer; the composite transition layer includes a carbon layer covering the surface of the oxide layer and an active material layer attached to the surface of the carbon layer.

[0125] The porosity of the nickel substrate is 90%-98%, preferably 95%; the average pore size of the nickel substrate is 100 μm-120 μm, preferably 110 μm.

[0126] The thickness of the oxide layer is 50nm-100nm; the carbon layer has a pore network of 10nm-100nm; and the active material layer has a microporous network of less than 10nm.

[0127] Among them, the microporous network, pore network, and micron-scale pore structure are interconnected.

[0128] The basic principles of the present disclosure have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this disclosure are merely illustrative and not restrictive, and should not be construed as necessarily possessed by each embodiment of the present disclosure. Furthermore, the specific details disclosed above are provided for illustrative purposes and to facilitate understanding, rather than as limitations. These details do not limit the present disclosure to necessarily being implemented using these specific details.

[0129] In the present disclosure, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. The block diagrams of the devices, devices, equipment, and systems involved in the present disclosure are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, devices, equipment, and systems can be connected, arranged, or configured in any manner. Words such as "including," "comprising," "having," and the like are open-ended words, meaning "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0130] It should also be noted that in the system and method of the present disclosure, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present disclosure.

[0131] Various changes, substitutions, and modifications may be made to the technology described herein without departing from the teachings defined by the appended claims. Moreover, the scope of the claims of this disclosure is not limited to the specific aspects of the processes, machines, manufactures, compositions of things, means, methods, and actions described above. Currently existing or later developed processes, machines, manufactures, compositions of things, means, methods, or actions that perform substantially the same function or achieve substantially the same results as the corresponding aspects described herein may be utilized. Accordingly, the appended claims include within their scope such processes, machines, manufactures, compositions of things, means, methods, or actions.

[0132] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0133] The above description has been provided for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present disclosure to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A multi-layer nickel electrode, characterized in that: include: A nickel base having uniform nanoscale pits formed on the surface of the nickel base and a micron-scale pore structure inside the nickel base; An oxide layer covering the surface of the nickel base and embedded in the pits; the oxide layer is a uniform nickel oxide layer formed on the surface of the nickel base, A composite transition layer covering the surface of the oxide layer; the composite transition layer includes a carbon layer covering the surface of the oxide layer and an active material layer attached to the surface of the carbon layer.

2. The multi-layered nickel electrode according to claim 1, characterized in that: The porosity of the nickel substrate is 90%-98%; The average pore size of the nickel substrate is 100 μm-120 μm; The thickness of the oxide layer is 50nm-100nm; The carbon layer has a pore network of 10nm-100nm; The active material layer has a microporous network with a diameter less than 10 nm.

3. A method for preparing a multi-layer nickel electrode, characterized in that: include: The base nickel foam is subjected to overall cleaning and surface activation treatment to obtain a first base nickel; The base nickel foam has a micron-scale pore structure inside; Treating the first nickel substrate with a plasma treatment process to obtain a second nickel substrate having uniform nanoscale pits formed on the surface; Performing a mild oxidation treatment on the surface of the second nickel base to form an oxide layer on the surface of the second nickel base; the oxide layer is a uniform nickel oxide layer embedded in the pit; Performing chemical vapor deposition on the second nickel substrate after oxidation to generate a carbon layer on the surface of the oxidation layer, and performing a mesoscopic pore network construction process on the carbon layer during the growth of the carbon layer; performing a surface activation treatment on the sample after the mesoscopic pore network construction treatment, and introducing a gas generating reagent to obtain an active material layer attached to the carbon layer; The processed sample is cleaned to obtain a multi-layer structure nickel electrode; The multi-layered nickel electrode includes a second base nickel, an oxide layer covering the surface of the second base nickel, a carbon layer covering the surface of the oxide layer, and an active material layer attached to the surface of the carbon layer. The carbon layer has a nanoscale pore network, and the active material layer has a microporous network with a pore size smaller than the pore size in the pore network.

4. The method for preparing a multi-layer nickel electrode according to claim 3, wherein: The method of performing overall cleaning and surface activation treatment on the base nickel foam to obtain the first base nickel comprises: The nickel foam substrate is sequentially placed in acetone, ethanol, and deionized water and ultrasonically treated for 15-20 minutes, and the treated nickel foam substrate is quickly dried with a nitrogen flow; The dried nickel foam substrate was placed in a vacuum drying oven at 50° C. to 55° C. for 1.5 to 2 hours to completely remove surface adsorbed water; Soaking the dried nickel foam substrate in a weak alkaline detergent for 10 to 20 minutes to activate the surface; The immersed base nickel foam is rinsed with deionized water and dried with a nitrogen flow to obtain a first base nickel.

5. The method for preparing a multi-layer nickel electrode according to claim 3, wherein: The method of treating the first nickel substrate with a plasma treatment process to obtain a second nickel substrate with uniform nanoscale pits formed on the surface thereof comprises: Placing the first nickel substrate in a plasma reaction chamber and evacuating the chamber to a basic vacuum degree of 0.5 Pa-1.5 Pa; Introduce Ar / O2 mixed gas, and adjust the working vacuum of the plasma reaction chamber to 45Pa-55Pa, and control the gas flow rate to 45sccm-55sccm; wherein, the volume proportion of Ar is 75%-85%, and the volume proportion of O2 is 15%-25%; The plasma power was set to 90W-110W, and the treatment was performed in pulse mode. The temperature was maintained at 23°C-27°C during the treatment process, and the total treatment time was 4.5 minutes-5.5 minutes. The pulse on time was 1.8s-2.2s, and the off time was 0.8s-1.2s. After the treatment is completed, the treated first nickel base is quickly taken out and placed in an inert gas environment to obtain a second nickel base; uniform nano-scale pits are formed on the surface of the second nickel base.

6. The method for preparing a multi-layer nickel electrode according to claim 3, wherein: The step of performing mild oxidation treatment on the surface of the second nickel substrate to form an oxide layer on the surface of the second nickel substrate comprises: The second nickel substrate is placed in a tube furnace and heat treated at 280° C. to 320° C. in a nitrogen atmosphere containing oxygen for 0.9 to 1.1 hours, with a heating rate of 4.5° C. / min to 5.5° C. / min; Among them, the volume proportion of oxygen in the mixed gas is 4%-6%; The thickness of the oxide layer is 50nm-100nm.

7. The method for preparing a multi-layer nickel electrode according to claim 3, wherein: The step of performing chemical vapor deposition on the second nickel substrate after oxidation to form a carbon layer on the surface of the oxide layer comprises: Placing the second nickel substrate after oxidation treatment in a chemical vapor deposition furnace and heating it to 680° C.-720° C.; Acetylene gas was introduced as a carbon source, with an acetylene gas flow rate of 45 sccm-55 sccm, and the reaction time was controlled at 28 minutes-32 minutes; After the carbon source gas is cut off, the mixture is naturally cooled to room temperature under nitrogen protection, and a carbon layer is formed on the surface of the oxide layer.

8. The method for preparing a multi-layer nickel electrode according to claim 7, wherein: During the growth of the carbon layer, the carbon layer is subjected to a mesoscopic pore network construction process, including: Before cutting off the carbon source gas and when introducing acetylene gas as the carbon source, adding polyvinyl pyrrolidone as a template agent, wherein the molecular weight of the polyvinyl pyrrolidone is in the range of 35000-45000 and the concentration is in the range of 4.5 mg / mL-5.5 mg / mL; After naturally cooling to room temperature under nitrogen protection, the sample with a carbon layer is heat-treated at 820°C-880°C to completely decompose the polyvinyl pyrrolidone and form a mesoscopic pore network in the carbon layer. The pore size range of the mesoscopic pore network is 10nm-100nm.

9. The method for preparing a multi-layer nickel electrode according to claim 7, wherein: Also includes: Introducing a nitrogen-containing precursor during a chemical vapor deposition process so that the carbon layer formed contains nitrogen doping; The nitrogen-containing precursor includes pyridine or ammonia.

10. The method for preparing a multi-layered nickel electrode according to claim 3, wherein: The sample after the mesoscopic pore network construction treatment is subjected to surface activation treatment, and a gas generating reagent is introduced to obtain an active material layer attached to the carbon layer; The treated sample is cleaned to obtain a multi-layer structure nickel electrode, including: soaking the treated sample containing the carbon layer in a nitric acid solution for 9 minutes to 11 minutes for surface activation treatment to form an active material layer; The treated sample is placed in a mixed solution of a first solution and a second solution containing 0.09 g to 0.11 g of carbamic acid, and soaked at 20° C. to 25° C. for 18 to 22 hours. The temperature is then raised to 75° C. to 85° C. and maintained for 3 to 5 hours to allow the carbamic acid to decompose and generate gas to form microscopic channels within the active material layer; the pore diameter of the microscopic channels is less than 10 nm; The first solution is 1.4g-1.6g Ni(NO3)2·6H2O dissolved in 22mL-26mL of isopropanol, and the second solution is 0.35g-0.45g Fe(SO4)2·7H2O dissolved in 7mL-9mL of deionized water; The treated sample was washed with deionized water to obtain a multi-layered nickel electrode.

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