Electrode and method for manufacturing electrode

Abstract

The present invention relates to an electrode and a method for manufacturing same, the electrode comprising: a nickel-containing metal substrate; a first sol-gel coating layer formed on at least one surface of the metal substrate; and a second sol-gel coating layer formed on the first sol-gel layer, wherein the first sol-gel coating layer and the second sol-gel coating layer each independently include nickel and iron. According to the present invention, the provided electrode for anion exchange membrane water electrolysis can implement improved electrochemical performance and has excellent durability.

Description

Electrodes and electrode manufacturing methods

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0103597, filed August 8, 2023, the entire contents of which are incorporated herein by reference.

[0003]

[0004] The present invention relates to an electrode and a method for manufacturing the same.

[0005]

[0006] The importance of environmentally friendly hydrogen production technology is being highlighted due to fossil fuel depletion and environmental pollution issues.

[0007] Accordingly, research on water electrolysis technology is being actively conducted, and representative low-temperature water electrolysis technologies include cation exchange membrane electrolysis (PEMWE), alkaline electrolysis (AWE), and anion exchange membrane electrolysis (AEMWE).

[0008] Alkaline water electrolysis offers the advantage of using relatively inexpensive non-platinum metals. However, it requires highly corrosion-resistant electrode materials, requires a large space, and has low current per electrode area, resulting in low efficiency.

[0009] Cation exchange membrane electrolysis allows for compact system design and has high energy density, but has the disadvantage of increasing hydrogen production costs because platinum-based metals must be used in the electrodes.

[0010] To overcome the shortcomings of these existing technologies, anion exchange membrane electrolysis (AEMWE) has been proposed.

[0011] In the case of anion exchange membrane electrolysis, there are advantages in that non-platinum metals can be used as electrode materials due to the alkaline environment, and a compact system design is possible, allowing for a satisfactory energy density.

[0012] However, the anion exchange membrane electrolysis method has not yet been sufficiently studied, and there is a significant lack of information on the standard exchange membrane and electrode materials.

[0013] Accordingly, active technological development and research on anion exchange membrane electrolysis are required to advance eco-friendly hydrogen production technology.

[0014]

[0015] The present specification provides an anion exchange membrane water electrolysis electrode having excellent durability while being capable of implementing improved electrochemical performance.

[0016] Additionally, the present specification provides a method for manufacturing the electrode.

[0017]

[0018] According to one aspect of the present invention, an electrode is provided, comprising: a first sol-gel coating layer formed on at least one surface of the metal substrate; and a second sol-gel coating layer formed on the first sol-gel layer; wherein the first sol-gel coating layer and the second sol-gel coating layer each independently include nickel and iron.

[0019]

[0020] In one example, the metal substrate may include a porous metal foam.

[0021]

[0022] According to one example, the first sol-gel coating layer and the second sol-gel coating layer may each independently include nickel hydroxide and iron hydroxide.

[0023]

[0024] According to one example, the first sol-gel coating layer and the second sol-gel coating layer may each independently exist in a state where nickel hydroxide and iron hydroxide form a three-dimensional gel network.

[0025]

[0026] According to one example, the first sol-gel coating layer and the second sol-gel coating layer may each independently include, with respect to 100 moles of nickel, about 10 to about 25 moles of iron, or about 10 moles or more, or about 15 moles or more, or about 16 moles or more, and about 25 moles or less, or about 20 moles or less, or about 18 moles or less.

[0027]

[0028] In one example, the thickness of the first sol-gel coating layer may be about 100 to about 250 nm, or about 100 nm or more, or about 150 nm or more, and about 250 nm or less, or about 200 nm or less.

[0029]

[0030] In one example, the thickness of the second sol-gel coating layer may be from about 500 to about 2000 nm, or greater than about 500 nm, or greater than about 800 nm, and less than about 2000 nm, or less than about 1000 nm.

[0031]

[0032] In one example, the thickness of the first sol-gel coating layer: the thickness of the second sol-gel coating layer may be from about 1:2 to about 1:10, or from about 1:5 to about 1:7, or from about 1:5 to about 1:6.67.

[0033]

[0034] In one example, the electrode may be used for anion exchange membrane electrolysis.

[0035]

[0036] Meanwhile, according to another aspect of the present invention, a method for manufacturing an electrode is provided, comprising: preparing a first precursor solution (sol) containing a nickel precursor and an iron precursor; immersing a nickel substrate in the first precursor solution; inducing a sol-gel reaction in the first precursor solution to form a first sol-gel coating layer on the nickel substrate; preparing a second precursor solution (sol) containing a nickel precursor and an iron precursor; immersing a nickel substrate in the second precursor solution; and inducing a sol-gel reaction in the second precursor solution to form a second sol-gel coating layer on the nickel substrate.

[0037]

[0038] According to one example, the nickel precursor may include at least one selected from the group consisting of a salt of nickel metal, a chloride salt, a bromine salt, a sulfuric acid salt, a nitrate salt, a carbonate salt, an acetate salt, a formic acid salt, an oxalic acid salt, and a citric acid salt.

[0039]

[0040] According to one example, the iron precursor may include at least one selected from the group consisting of a salt of iron metal, a chloride salt, a bromine salt, a sulfuric acid salt, a nitrate salt, a carbonate salt, an acetate salt, a formic acid salt, an oxalic acid salt, and a citric acid salt.

[0041]

[0042] According to one example, the electrode manufacturing method may further include a step of stabilizing the formed first sol-gel coating layer after forming the first sol-gel coating layer.

[0043]

[0044] According to one example, the stabilizing step may include one or more of the following steps: i) drying the electrode substrate on which the first sol-gel coating layer is formed, and ii) heat treating the electrode substrate on which the first sol-gel coating layer is formed.

[0045]

[0046] According to one example, the electrode manufacturing method may further include a step of stabilizing the formed second sol-gel coating layer after forming the second sol-gel coating layer.

[0047]

[0048] According to one example, the stabilizing step may include one or more of the following steps: i) drying the electrode substrate on which the second sol-gel coating layer is formed, and ii) heat treating the electrode substrate on which the second sol-gel coating layer is formed.

[0049]

[0050] In the present invention, terms such as first, second, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another.

[0051] Additionally, the terms used herein are merely used to describe exemplary embodiments and are not intended to limit the present invention.

[0052] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0053] In this specification, the terms “comprise,” “include,” or “have” are intended to describe a feature, number, step, component, or combination thereof implemented, but do not exclude the possibility of one or more other features, numbers, steps, components, combinations, or additions thereof.

[0054] Additionally, in this specification, when each layer or element is referred to as being formed “on” or “over” each layer or element, it means that each layer or element is formed directly on each layer or element, or that other layers or elements may be additionally formed between each layer, on the object, or on the substrate.

[0055] The present invention is susceptible to various modifications and takes various forms. Specific embodiments are illustrated and described in detail below. However, this does not limit the invention to a specific disclosed form, but rather encompasses all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0056]

[0057] Hereinafter, the present invention will be described in detail.

[0058]

[0059] According to one aspect of the present invention, an electrode is provided, comprising: a first sol-gel coating layer formed on at least one surface of the metal substrate; and a second sol-gel coating layer formed on the first sol-gel layer; wherein the first sol-gel coating layer and the second sol-gel coating layer each independently include nickel and iron.

[0060]

[0061] In this specification, the term "electrode includes a metal such as nickel or iron" means not only the metal element itself, but also ions of the metal element, or compounds thereof.

[0062]

[0063] An electrode according to an example of the present invention can be produced at a lower cost than an electrode using a precious metal such as platinum, by using nickel and iron as active materials.

[0064] In addition, due to the multilayer structure including multiple sol-gel coating layers containing nickel and iron, it is possible to realize superior electrochemical performance compared to a single-layer structure, and the durability of the coating layer is excellent, so that high safety and stability can be secured.

[0065]

[0066] The inventors of the present invention have discovered that, in an electrode used in a water electrolysis process, and particularly in an electrode used in an anion exchange membrane water electrolysis process, when a plurality of sol-gel coating layers containing a catalyst component are formed on a metal substrate, the electrode can exhibit excellent electrochemical performance in a water electrolysis reaction, while also providing an electrode with excellent durability of the coating layer, and have thus completed the present invention.

[0067]

[0068] In an example electrode, the first and second sol-gel coating layers formed on at least one surface of the substrate each independently contain nickel and iron, and the first and second sol-gel coating layers containing nickel and iron can function as a catalyst that mediates oxygen generation by water electrolysis. That is, the electrode according to the example includes a catalyst layer having a multi-layer structure, namely, the first and second sol-gel coating layers, and the catalyst layer having a multi-layer structure is the first and second sol-gel coating layers containing nickel and iron.

[0069]

[0070] For example, the metal substrate may include a porous metal foam. However, this is only one example of a substrate type for the electrode that provides a large surface area for the reaction and facilitates rapid diffusion of reactants and products, and the present invention is not necessarily limited thereto.

[0071] For example, the porosity of the metal foam may be about 50 to about 200 PPI (Pores per inch), or about 70 to about 170 PPI, or about 110 PPI.

[0072] Additionally, the thickness of the nickel metal may be 150 to 350 μm, specifically 200 to 300 μm, for example 250 μm.

[0073] According to one example, the first sol-gel coating layer and the second sol-gel coating layer may each independently include nickel hydroxide and iron hydroxide.

[0074]

[0075] According to one example, the first sol-gel coating layer and the second sol-gel coating layer may each independently exist in a state where nickel hydroxide and iron hydroxide form a three-dimensional gel network.

[0076]

[0077] Here, the sol-gel layer containing nickel and iron can be completely distinguished in terms of its composition and structure from a general metal plating layer in which nickel and iron metal atoms are directly deposited on a substrate, or a simple coating layer in which a metal compound containing nickel and iron elements, respectively, is adsorbed or attached on a substrate.

[0078] The sol-gel coating layer is a layer formed by the sol-gel process and may also be called a sol-gel film, a sol-gel membrane, or a sol-gel coating layer.

[0079] Simple metal compound coating layers, other than sol-gel coating layers, can be formed using electrochemical methods such as electrolytic coating using metal compounds, physical vapor deposition, or coating methods. These general compound coating layers are formed relatively thicker and rougher than sol-gel coating layers, and are less uniform in thickness and particle size.

[0080] However, the sol-gel coating layer formed by the sol-gel process using a metal precursor can have a uniform nanoscale structure and unique physical properties resulting from it. Specifically, when the sol-gel coating layer is formed using a nickel precursor and an iron precursor, the nickel precursor and iron precursor compounds are converted into nickel compounds and iron compounds different from the original during the sol-gel process, respectively, and a solid network is formed between each compound during this process, forming a three-dimensional gel structure. This three-dimensional gel structure can include micropores, and its structure and properties can change depending on post-processing such as drying and heat treatment. Due to these properties, the sol-gel coating layer formed by the sol-gel process can provide a larger surface area for the water electrolysis reaction on the electrode, and promote the rapid diffusion of reactants and products, thereby improving the overall efficiency of the water electrolysis reaction.

[0081] In addition, when a sol-gel coating layer is formed by a sol-gel process, it can be distinguished from a general metal plating layer or metal compound coating layer in that the microstructure such as a three-dimensional gel structure or pores and the size of the structure can be controlled.

[0082]

[0083] And, the electrode according to one aspect of the present invention can significantly improve the efficiency of the reaction and the durability of the electrode structure by including at least two layers of sol-gel coating layers including nickel and iron, such as a first sol-gel coating layer and a second coating layer.

[0084] A multilayer sol-gel coating layer such as a double layer is a completely distinct concept from i) a single-structure sol-gel coating layer, ii) a double-layer structure in which any two of a sol-gel coating layer, a metal plating layer, and a compound simple coating layer are selected, or iii) a compound with a layered double composition.

[0085] In particular, considering that a compound having a layered double structure is a type of ionic solid, and is a two-dimensional multilayer compound in which a metal cation layer, a hydroxide ion layer, and a layer in which other anions or neutral molecules exist are repeated, such a compound having a layered double structure is completely different from the sol-gel coating layer of a three-dimensional gel structure as mentioned in the present invention, which is formed in multiple layers, only in that the compound itself has a double-layer structure. This is the same even if the compound having a layered double structure is coated in multiple layers.

[0086]

[0087] According to one example, the first sol-gel coating layer and the second sol-gel coating layer may each independently include, with respect to 100 moles of nickel, about 10 to about 25 moles of iron, or about 10 moles or more, or about 15 moles or more, or about 16 moles or more, and about 25 moles or less, or about 20 moles or less, or about 18 moles or less.

[0088] If the nickel ratio or iron ratio becomes excessively high outside the above range, the overvoltage phenomenon may increase, which may reduce the catalyst performance and lifespan.

[0089]

[0090] In one example, the thickness of the first sol-gel coating layer may be about 100 to about 250 nm, or about 100 nm or more, or about 150 nm or more, and about 250 nm or less, or about 200 nm or less.

[0091] If the thickness of the first coating layer is too thin outside the above range, the advantage of the layered double structure may not be obtained, and if the thickness is too thick, the pores of the electrode may be blocked, thereby hindering material transfer.

[0092]

[0093] In one example, the thickness of the second sol-gel coating layer may be from about 500 to about 2000 nm, or greater than about 500 nm, or greater than about 800 nm, and less than about 2000 nm, or less than about 1000 nm.

[0094] If the thickness of the second coating layer is too thin outside the above range, the advantage of the layered double structure may not be obtained, and if the thickness is too thick, the pores of the electrode may be blocked, hindering material transfer.

[0095]

[0096] In one example, the thickness of the first sol-gel coating layer: the thickness of the second sol-gel coating layer may be from about 1:2 to about 1:10, or from about 1:5 to about 1:7, or from about 1:5 to about 1:6.67.

[0097] The thickness of the first coating layer may vary depending on heat treatment or drying conditions during the second coating layer formation process after the formation of the first coating layer. In this case, if the ratio of the first coating layer and the second coating layer is outside the above range, the advantage of the layered double structure may not be obtained.

[0098]

[0099]

[0100] In one example, the electrode may be used for anion exchange membrane electrolysis.

[0101]

[0102] Meanwhile, according to another aspect of the present invention, a method for manufacturing an electrode is provided, comprising: preparing a first precursor solution (sol) containing a nickel precursor and an iron precursor; immersing a nickel substrate in the first precursor solution; inducing a sol-gel reaction in the first precursor solution to form a first sol-gel coating layer on the nickel substrate; preparing a second precursor solution (sol) containing a nickel precursor and an iron precursor; immersing a nickel substrate in the second precursor solution; and inducing a sol-gel reaction in the second precursor solution to form a second sol-gel coating layer on the nickel substrate.

[0103]

[0104] For example, the nickel precursor may include a salt of nickel metal, such as a chloride salt, a bromide salt, a sulfuric acid salt, a nitrate salt, a carbonate salt, an acetate salt, a formic acid salt, an oxalic acid salt, and a citric acid salt. However, the present invention is not necessarily limited thereto, and the precursor may be appropriately selected in consideration of the solvent to be used in the sol-gel process, the structure of the sol-gel coating layer to be ultimately formed, and the like.

[0105]

[0106] For example, the iron precursor may include a salt of iron metal, such as a chloride salt, a bromide salt, a sulfuric acid salt, a nitrate salt, a carbonate salt, an acetate salt, a formic acid salt, an oxalic acid salt, and a citric acid salt. However, the present invention is not necessarily limited thereto, and the precursor may be appropriately selected in consideration of the solvent to be used in the sol-gel process, the structure of the sol-gel coating layer to be ultimately formed, and the like.

[0107]

[0108] A first precursor solution in a sol state containing the nickel precursor and iron precursor as described above is prepared. The solvent used in the solution is not particularly limited; however, considering that the nickel precursor and iron precursor form a gel in the form of metal hydroxides during the sol-gel reaction, it may be preferable to use a polar solvent other than water that has good compatibility with water.

[0109] Such polar solvents may specifically include, for example, one or more selected from the group consisting of methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, dimethyl ether, diethyl ether, methyl ethyl ether, tetrahydrofuran, acetic acid, dimethylformamide, and nitromethane.

[0110] The concentration of nickel in the first precursor solution may be about 0.1 to about 10 M. And, the concentration of iron in the first precursor solution may be about 0.01 to about 1 M. However, the present invention is not necessarily limited thereto, and the amount of each chemical species used may be appropriately varied to control the content of nickel and iron in the final product, the relative ratio of the two, or the three-dimensional network structure of the gel, the size of the micropores, etc.

[0111]

[0112] When preparing the first precursor solution, the method is not particularly limited. Specifically, a first precursor solution in a sol state can be prepared by adding an appropriate amount of the precursor materials to a solvent and stirring, etc.

[0113] Additionally, prior to immersing the nickel substrate in the first precursor solution, an acid treatment process may be performed, in which the nickel substrate is immersed in acid. This acid treatment process removes any oxide layer that may have formed on the surface of the nickel substrate, increases surface roughness, and allows for a thicker catalyst coating layer.

[0114] When treating with acid, an acid substance such as hydrochloric acid, nitric acid, or sulfuric acid can be used, and it may be preferable to use an acid aqueous solution having a concentration of about 1 to about 20 wt%.

[0115]

[0116] A nickel substrate is immersed in the first precursor solution as described above, and a sol-gel reaction is induced. As described above, nickel and iron primarily form a three-dimensional network-structured gel in the form of metal hydroxides in the sol-gel reaction. Therefore, the sol-gel reaction can be induced by methods such as adding water to the solution and stirring.

[0117] However, this is also just one example, and in order to control the structure or size of the gel, a three-dimensional network structure gel can be formed in the form of a compound other than a metal hydroxide, and accordingly, a sol-gel reaction can be induced using a solvent other than water, and when adding, water and another solvent can be used by appropriately mixing them.

[0118] For example, compounds of the alkylene oxide series can play a role in converting the precursor hydrate into a precursor hydroxide by taking hydrogen ions from the hydrate when a precursor and a solvent meet to form a hydrate, and these precursor hydroxides can bond with each other around oxygen to form a gel structure.

[0119]

[0120] According to one example, the electrode manufacturing method may further include a step of stabilizing the formed first sol-gel coating layer after forming the first sol-gel coating layer.

[0121]

[0122] According to one example, the stabilizing step may include one or more of the following steps: i) drying the electrode substrate on which the first sol-gel coating layer is formed, and ii) heat treating the electrode substrate on which the first sol-gel coating layer is formed.

[0123] Drying can be carried out for about 1 to 24 hours at a temperature of about 10°C to about 150°C, and it may be advantageous in terms of drying efficiency to carry out drying under reduced pressure or vacuum conditions.

[0124] And during heat treatment, it may be desirable for the temperature to be about 200°C to about 500°C.

[0125] The above heat treatment can be distinguished from simple drying conditions in that it is a process for enhancing electrochemical properties while preventing side reactions under certain conditions such as a specific temperature and an inert gas atmosphere.

[0126] Heat treatment can create an amorphous state and form a thick catalyst layer, significantly improving catalyst performance. Furthermore, increasing the heat treatment temperature can create a crystallized state, preventing the catalyst layer from delaminating and significantly improving the long-term stability of the catalyst.

[0127]

[0128] Afterwards, a second sol-gel coating layer is formed again on the substrate on which the first sol-gel coating layer is formed.

[0129] First, a second precursor solution containing a nickel precursor and an iron precursor is prepared.

[0130] Just as the first sol-gel coating layer and the second sol-gel coating layer are independent of each other, the second precursor solution may also be the same as or different from the first precursor solution.

[0131]

[0132] For example, the nickel precursor may include a salt of nickel metal, such as a chloride salt, a bromide salt, a sulfuric acid salt, a nitrate salt, a carbonate salt, an acetate salt, a formic acid salt, an oxalic acid salt, and a citric acid salt. However, the present invention is not necessarily limited thereto, and the precursor may be appropriately selected in consideration of the solvent to be used in the sol-gel process, the structure of the sol-gel coating layer to be ultimately formed, and the like.

[0133]

[0134] For example, the iron precursor may include a salt of iron metal, such as a chloride salt, a bromide salt, a sulfuric acid salt, a nitrate salt, a carbonate salt, an acetate salt, a formic acid salt, an oxalic acid salt, and a citric acid salt. However, the present invention is not necessarily limited thereto, and the precursor may be appropriately selected in consideration of the solvent to be used in the sol-gel process, the structure of the sol-gel coating layer to be ultimately formed, and the like.

[0135]

[0136] A second precursor solution in a sol state containing the nickel precursor and iron precursor as described above is prepared. The solvent used in the solution is not particularly limited; however, considering that the nickel precursor and iron precursor form a gel in the form of metal hydroxides during the sol-gel reaction, it may be desirable to use a polar solvent other than water that has good compatibility with water.

[0137] Such polar solvents may specifically include, for example, one or more selected from the group consisting of methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, dimethyl ether, diethyl ether, methyl ethyl ether, tetrahydrofuran, acetic acid, dimethylformamide, and nitromethane.

[0138] The concentration of nickel in the second precursor solution may be about 0.1 to about 10 M. And, the concentration of iron in the second precursor solution may be about 0.01 to about 1 M. However, the present invention is not necessarily limited thereto, and the amount of each chemical species used may be appropriately varied to control the content of nickel and iron in the final product, the relative ratio of the two, or the three-dimensional network structure of the gel, the size of the micropores, etc.

[0139]

[0140] When preparing the second precursor solution, the method is not particularly limited. Specifically, a second precursor solution in a sol state can be prepared by adding an appropriate amount of the precursor materials to a solvent and stirring, etc.

[0141] A nickel substrate is immersed in the second precursor solution described above, and a sol-gel reaction is induced. As described above, nickel and iron primarily form a three-dimensional network-structured gel in the form of metal hydroxides in the sol-gel reaction. Therefore, the sol-gel reaction can be induced by methods such as adding water to the solution described above and stirring it.

[0142] However, this is also just one example, and in order to control the structure or size of the gel, a three-dimensional network structure gel can be formed in the form of a compound other than a metal hydroxide, and accordingly, a sol-gel reaction can be induced using a solvent other than water, and when adding, water and another solvent can be used by appropriately mixing them.

[0143]

[0144] According to one example, the electrode manufacturing method may further include a step of stabilizing the formed second sol-gel coating layer after forming the second sol-gel coating layer.

[0145]

[0146] According to one example, the stabilizing step may include one or more of the following steps: i) drying the electrode substrate on which the second sol-gel coating layer is formed, and ii) heat treating the electrode substrate on which the second sol-gel coating layer is formed.

[0147] Drying can be carried out for about 1 to 24 hours at a temperature of about 10°C to about 150°C, and it may be advantageous in terms of drying efficiency to carry out drying under reduced pressure or vacuum conditions.

[0148] And during heat treatment, it may be desirable for the temperature to be about 200°C to about 500°C.

[0149]

[0150] According to one example of the present invention, an anion exchange membrane water electrolysis electrode having excellent durability and capable of implementing improved electrochemical performance can be provided.

[0151]

[0152] Figures 1 to 4 are FIB-SEM images observing the cross-section of an electrode manufactured according to an example of the present invention.

[0153] Figures 5 and 6 are graphs showing the performance evaluation results of an electrode manufactured according to an example of the present invention.

[0154]

[0155] Hereinafter, the functions and effects of the invention will be described in more detail through specific examples. However, these examples are provided merely as examples of the invention and do not define the scope of the invention.

[0156]

[0157] <Example>

[0158] Comparative Example 1: Single Layer

[0159] 10 ml of ethanol was added to the flask, 10.5 mmol of NiCl2·6H2O and 1.75 mmol of FeCl3 were added, and the mixture was stirred at 750 rpm for 2 hours using a cooling ball. (Preparation of the first precursor solution)

[0160] In a separate vial, 10 ml of ethanol and 9 ml of deionized water were prepared.

[0161] Separately, a 15 wt% hydrochloric acid aqueous solution was prepared in a flask, and a nickel foam gas diffusion layer (manufacturer: Alantum foam; product name: PN-04) was immersed in the solution and subjected to acid treatment for 15 minutes.

[0162] The acid-treated nickel foam GDL was taken out of the flask, rinsed once in deionized water, and then placed in the first precursor solution, while simultaneously adding the ethanol and deionized water in the vial to the first precursor solution.

[0163] 5 ml of propylene oxide was added dropwise to the mixed solution while stirring at 200 rpm for about 1 minute, and the solution was stirred at 200 rpm for 24 hours after the addition was completed.

[0164] After 24 hours, the nickel foam GDL was removed and soaked in an acetone solution for about 5 days to remove foreign substances.

[0165] After acetone washing, it was placed in a vacuum oven and dried at about 100°C for about 10 hours.

[0166] The electrode on which the coating layer was formed was placed in an oven under an argon atmosphere, purged at about 30°C for 30 minutes, then heated to about 200°C at a rate of 5°C / min, and heat treated while maintaining the temperature at this temperature for 1 hour.

[0167]

[0168] Example 1: Dry_200

[0169] Formation of the first sol-gel coating layer

[0170] 10 ml of ethanol was added to the flask, 10.5 mmol of NiCl2·6H2O and 1.75 mmol of FeCl3 were added, and the mixture was stirred at 750 rpm for 2 hours using a cooling ball. (Preparation of the first precursor solution)

[0171] In a separate vial, 10 ml of ethanol and 9 ml of deionized water were prepared.

[0172] Separately, a 15 wt% hydrochloric acid aqueous solution was prepared in a flask, and a nickel foam gas diffusion layer (manufacturer: Alantum foam; product name: PN-04) was immersed in the solution and subjected to acid treatment for 15 minutes.

[0173] The acid-treated nickel foam GDL was taken out of the flask, rinsed once in deionized water, and then placed in the first precursor solution, while simultaneously adding the ethanol and deionized water in the vial to the first precursor solution.

[0174] 5 ml of propylene oxide was added dropwise to the mixed solution while stirring at 200 rpm for about 1 minute, and the solution was stirred at 200 rpm for 24 hours after the addition was completed.

[0175] After 24 hours, the nickel foam GDL was removed and soaked in an acetone solution for about 5 days to remove foreign substances.

[0176] After acetone washing, it was placed in a vacuum oven and dried at about 100°C for about 10 hours.

[0177]

[0178] Formation of the second sol-gel coating layer

[0179] 10 ml of ethanol was added to the flask, 10.5 mmol of NiCl2·6H2O and 1.75 mmol of FeCl3 were added, and the mixture was stirred at 750 rpm for 2 hours using a cooling ball. (Preparation of the second precursor solution)

[0180] In a separate vial, 10 ml of ethanol and 9 ml of deionized water were prepared.

[0181] The nickel foam GDL, on which the first sol-gel coating layer was formed, was placed into the first precursor solution, and at the same time, ethanol and deionized water contained in the vial were also added to the first precursor solution.

[0182] 5 ml of propylene oxide was added dropwise to the mixed solution while stirring at 200 rpm for about 1 minute, and the solution was stirred at 200 rpm for 24 hours after the addition was completed.

[0183] After 24 hours, the nickel foam GDL was removed and soaked in an acetone solution for about 5 days to remove foreign substances.

[0184] After acetone washing, it was placed in a vacuum oven and dried at about 100°C for about 10 hours.

[0185]

[0186] heat treatment

[0187] The electrode on which the second sol-gel coating layer was formed was placed in an oven under an argon atmosphere, purged at about 30°C for 30 minutes, and then heated to about 200°C at a rate of 5°C / min, and heat treated while maintaining the temperature at this temperature for 1 hour.

[0188]

[0189] An image of the cross-section of the electrode manufactured in the above example observed using FIB-SEM is shown in Fig. 1.

[0190]

[0191] Example 2: Dry_400

[0192] Formation of the first sol-gel coating layer

[0193] 10 ml of ethanol was added to the flask, 10.5 mmol of NiCl2·6H2O and 1.75 mmol of FeCl3 were added, and the mixture was stirred at 750 rpm for 2 hours using a cooling ball. (Preparation of the first precursor solution)

[0194] In a separate vial, 10 ml of ethanol and 9 ml of deionized water were prepared.

[0195] Separately, a 15 wt% hydrochloric acid aqueous solution was prepared in a flask, and a nickel foam gas diffusion layer (manufacturer: Alantum foam; product name: PN-04) was immersed in the solution and subjected to acid treatment for 15 minutes.

[0196] The acid-treated nickel foam GDL was taken out of the flask, rinsed once in deionized water, and then placed in the first precursor solution, while simultaneously adding the ethanol and deionized water in the vial to the first precursor solution.

[0197] 5 ml of propylene oxide was added dropwise to the mixed solution while stirring at 200 rpm for about 1 minute, and the solution was stirred at 200 rpm for 24 hours after the addition was completed.

[0198] After 24 hours, the nickel foam GDL was removed and soaked in an acetone solution for about 5 days to remove foreign substances.

[0199] After acetone washing, it was placed in a vacuum oven and dried at about 100°C for about 10 hours.

[0200]

[0201] Formation of the second sol-gel coating layer

[0202] 10 ml of ethanol was added to the flask, 10.5 mmol of NiCl2·6H2O and 1.75 mmol of FeCl3 were added, and the mixture was stirred at 750 rpm for 2 hours using a cooling ball. (Preparation of the second precursor solution)

[0203] In a separate vial, 10 ml of ethanol and 9 ml of deionized water were prepared.

[0204] The nickel foam GDL, on which the first sol-gel coating layer was formed, was placed into the first precursor solution, and at the same time, ethanol and deionized water contained in the vial were also added to the first precursor solution.

[0205] 5 ml of propylene oxide was added dropwise to the mixed solution while stirring at 200 rpm for about 1 minute, and the solution was stirred at 200 rpm for 24 hours after the addition was completed.

[0206] After 24 hours, the nickel foam GDL was removed and soaked in an acetone solution for about 5 days to remove foreign substances.

[0207] After acetone washing, it was placed in a vacuum oven and dried at about 100°C for about 10 hours.

[0208]

[0209] heat treatment

[0210] The electrode on which the second sol-gel coating layer was formed was placed in an oven under an argon atmosphere, purged at about 30°C for 30 minutes, and then heated to about 400°C at a rate of 5°C / min, and heat treated while maintaining the temperature at this temperature for 1 hour.

[0211]

[0212] An image of the cross-section of the electrode manufactured in the above example observed using FIB-SEM is shown in Fig. 2.

[0213]

[0214] Example 3: 200_200

[0215] Formation of the first sol-gel coating layer

[0216] 10 ml of ethanol was added to the flask, 10.5 mmol of NiCl2·6H2O and 1.75 mmol of FeCl3 were added, and the mixture was stirred at 750 rpm for 2 hours using a cooling ball. (Preparation of the first precursor solution)

[0217] In a separate vial, 10 ml of ethanol and 9 ml of deionized water were prepared.

[0218] Separately, a 15 wt% hydrochloric acid aqueous solution was prepared in a flask, and a nickel foam gas diffusion layer (manufacturer: Alantum foam; product name: PN-04) was immersed in the solution and subjected to acid treatment for 15 minutes.

[0219] The acid-treated nickel foam GDL was taken out of the flask, rinsed once in deionized water, and then placed in the first precursor solution, while simultaneously adding the ethanol and deionized water in the vial to the first precursor solution.

[0220] 5 ml of propylene oxide was added dropwise to the mixed solution while stirring at 200 rpm for about 1 minute, and the solution was stirred at 200 rpm for 24 hours after the addition was completed.

[0221] After 24 hours, the nickel foam GDL was removed and soaked in an acetone solution for about 5 days to remove foreign substances.

[0222] After acetone washing, it was placed in a vacuum oven and dried at about 100°C for about 10 hours.

[0223]

[0224] heat treatment

[0225] The electrode on which the second sol-gel coating layer was formed was placed in an oven under an argon atmosphere, purged at about 30°C for 30 minutes, and then heated to about 200°C at a rate of 5°C / min, and heat treated while maintaining the temperature at this temperature for 1 hour.

[0226]

[0227] Formation of the second sol-gel coating layer

[0228] 10 ml of ethanol was added to the flask, 10.5 mmol of NiCl2·6H2O and 1.75 mmol of FeCl3 were added, and the mixture was stirred at 750 rpm for 2 hours using a cooling ball. (Preparation of the second precursor solution)

[0229] In a separate vial, 10 ml of ethanol and 9 ml of deionized water were prepared.

[0230] The nickel foam GDL, on which the first sol-gel coating layer was formed, was placed into the first precursor solution, and at the same time, ethanol and deionized water contained in the vial were also added to the first precursor solution.

[0231] 5 ml of propylene oxide was added dropwise to the mixed solution while stirring at 200 rpm for about 1 minute, and the solution was stirred at 200 rpm for 24 hours after the addition was completed.

[0232] After 24 hours, the nickel foam GDL was removed and soaked in an acetone solution for about 5 days to remove foreign substances.

[0233] After acetone washing, it was placed in a vacuum oven and dried at about 100°C for about 10 hours.

[0234]

[0235] heat treatment

[0236] The electrode on which the second sol-gel coating layer was formed was placed in an oven under an argon atmosphere, purged at about 30°C for 30 minutes, and then heated to about 200°C at a rate of 5°C / min, and heat treated while maintaining the temperature at this temperature for 1 hour.

[0237]

[0238] An image of the cross-section of the electrode manufactured in the above example observed using FIB-SEM is shown in Fig. 3.

[0239]

[0240] Example 4: 400_400

[0241] Formation of the first sol-gel coating layer

[0242] 10 ml of ethanol was added to the flask, 10.5 mmol of NiCl2·6H2O and 1.75 mmol of FeCl3 were added, and the mixture was stirred at 750 rpm for 2 hours using a cooling ball. (Preparation of the first precursor solution)

[0243] In a separate vial, 10 ml of ethanol and 9 ml of deionized water were prepared.

[0244] Separately, a 15 wt% hydrochloric acid aqueous solution was prepared in a flask, and a nickel foam gas diffusion layer (manufacturer: Alantum foam; product name: PN-04) was immersed in the solution and subjected to acid treatment for 15 minutes.

[0245] The acid-treated nickel foam GDL was taken out of the flask, rinsed once in deionized water, and then placed in the first precursor solution, while simultaneously adding the ethanol and deionized water in the vial to the first precursor solution.

[0246] 5 ml of propylene oxide was added dropwise to the mixed solution while stirring at 200 rpm for about 1 minute, and the solution was stirred at 200 rpm for 24 hours after the addition was completed.

[0247] After 24 hours, the nickel foam GDL was removed and soaked in an acetone solution for about 5 days to remove foreign substances.

[0248] After acetone washing, it was placed in a vacuum oven and dried at about 100°C for about 10 hours.

[0249]

[0250] heat treatment

[0251] The electrode on which the second sol-gel coating layer was formed was placed in an oven under an argon atmosphere, purged at about 30°C for 30 minutes, and then heated to about 400°C at a rate of 5°C / min, and heat treated while maintaining the temperature at this temperature for 1 hour.

[0252]

[0253] Formation of the second sol-gel coating layer

[0254] 10 ml of ethanol was added to the flask, 10.5 mmol of NiCl2·6H2O and 1.75 mmol of FeCl3 were added, and the mixture was stirred at 750 rpm for 2 hours using a cooling ball. (Preparation of the second precursor solution)

[0255] In a separate vial, 10 ml of ethanol and 9 ml of deionized water were prepared.

[0256] The nickel foam GDL, on which the first sol-gel coating layer was formed, was placed into the first precursor solution, and at the same time, ethanol and deionized water contained in the vial were also added to the first precursor solution.

[0257] 5 ml of propylene oxide was added dropwise to the mixed solution while stirring at 200 rpm for about 1 minute, and the solution was stirred at 200 rpm for 24 hours after the addition was completed.

[0258] After 24 hours, the nickel foam GDL was removed and soaked in an acetone solution for about 5 days to remove foreign substances.

[0259] After acetone washing, it was placed in a vacuum oven and dried at about 100°C for about 10 hours.

[0260]

[0261] heat treatment

[0262] The electrode on which the second sol-gel coating layer was formed was placed in an oven under an argon atmosphere, purged at about 30°C for 30 minutes, and then heated to about 400°C at a rate of 5°C / min, and heat treated while maintaining the temperature at this temperature for 1 hour.

[0263]

[0264] An image of the cross-section of the electrode manufactured in the above example observed using FIB-SEM is shown in Fig. 4.

[0265]

[0266] Electrode evaluation

[0267] For the electrodes manufactured in the above examples and comparative examples, the current (current density) was measured while changing the voltage, and the results are shown in Figs. 5 and 6.

[0268]

[0269] Figure 5 shows the results of evaluating the electrode manufactured in Example 1. Referring to Figure 5, it can be clearly seen that the performance at a voltage of 1.9 V has increased by about 20% or more compared to the comparative example in which a single coating was formed.

[0270]

[0271] Figure 6 shows the results of evaluating the electrodes manufactured in Examples 1 and 3. Referring to Figure 6, it can be clearly confirmed that the electrical performance of the electrode according to one embodiment of the present invention is very excellent.

Claims

1. Metal substrate containing nickel; A first sol-gel coating layer formed on at least one surface of the metal substrate; and A second sol-gel coating layer formed on the first sol-gel layer; An electrode wherein the first sol-gel coating layer and the second sol-gel coating layer each independently contain nickel and iron.

2. In paragraph 1, The above metal substrate is an electrode including a porous metal foam.

3. In paragraph 1, An electrode wherein the first sol-gel coating layer and the second sol-gel coating layer each independently comprise nickel hydroxide and iron hydroxide.

4. In paragraph 1, An electrode in which the first sol-gel coating layer and the second sol-gel coating layer are each independently formed in a state in which nickel hydroxide and iron hydroxide form a three-dimensional gel network.

5. In paragraph 1, An electrode wherein the first sol-gel coating layer and the second sol-gel coating layer each independently contain 10 to 25 moles of iron per 100 moles of nickel.

6. In paragraph 1, An electrode wherein the thickness of the first sol-gel coating layer is 100 to 200 nm.

7. In paragraph 1, An electrode wherein the thickness of the second sol-gel coating layer is 500 to 2000 nm.

8. In paragraph 1, An electrode wherein the thickness of the first sol-gel coating layer: the thickness of the second sol-gel coating layer is 1:2 to 1:

10.

9. In paragraph 1, Anion exchange membrane for electrolysis, electrode.

10. A step of preparing a first precursor solution (sol) containing a nickel precursor and an iron precursor; A step of immersing a nickel substrate in the first precursor solution; A step of forming a first sol-gel coating layer on a nickel substrate by inducing a sol-gel reaction in the first precursor solution; A step of preparing a second precursor solution (sol) containing a nickel precursor and an iron precursor; a step of immersing the nickel substrate in the second precursor solution; and A step of forming a second sol-gel coating layer on a nickel substrate by inducing a sol-gel reaction in the second precursor solution; Method for manufacturing electrodes.

11. In paragraph 10, A method for manufacturing an electrode, wherein the nickel precursor comprises at least one salt of nickel metal selected from the group consisting of chlorine salts, bromine salts, sulfuric acid salts, nitrate salts, carbonate salts, acetate salts, formic acid salts, oxalic acid salts, and citric acid salts.

12. In paragraph 10, A method for manufacturing an electrode, wherein the iron precursor comprises at least one salt of iron metal selected from the group consisting of chlorine salts, bromine salts, sulfuric acid salts, nitrate salts, carbonate salts, acetate salts, formic acid salts, oxalic acid salts, and citric acid salts.

13. In paragraph 10, A method for manufacturing an electrode, further comprising a step of stabilizing the formed first sol-gel coating layer after forming the first sol-gel coating layer.

14. In paragraph 13, A method for manufacturing an electrode, wherein the stabilizing step comprises at least one of: i) a step of drying an electrode substrate having a first sol-gel coating layer formed thereon, and ii) a step of heat-treating an electrode substrate having a first sol-gel coating layer formed thereon.

15. In paragraph 10, A method for manufacturing an electrode, further comprising a step of stabilizing the formed second sol-gel coating layer after forming the second sol-gel coating layer.

16. In paragraph 15, A method for manufacturing an electrode, wherein the stabilizing step comprises at least one of: i) a step of drying an electrode substrate having a second sol-gel coating layer formed thereon, and ii) a step of heat-treating an electrode substrate having a second sol-gel coating layer formed thereon.

Images