KR20210091891A - Method for manufacturing electrode having a catalyst layer including layered double hydroxide(LDH) - Google Patents

Abstract

The present invention provides a method for manufacturing an electrode which comprises: a step of preparing an electrode base material comprising a first metal and a solution comprising a second metal; and a step of forming a catalyst layer comprising layered double hydroxide (LDH) on a surface of the electrode base material by immersing the electrode base material comprising a first metal in the solution comprising a second metal, and inducing spontaneous oxidation of the first metal positioned on the surface of the electrode base material, wherein the catalyst layer on the surface of the electrode base material is in a chemically bonded form. According to the present invention, durability can be improved when the electrode is used as an electrode for an alkaline hydrolysis electrode.

Description

A method for manufacturing an electrode having a catalyst layer including a double-layered hydroxide structure (LDH) and an alkaline water electrolysis electrode using the same

The present invention relates to a method for manufacturing an electrode used in an electrochemical system, and more particularly, to a method for manufacturing an electrode in which a catalyst layer including a double-layer hydroxide structure (LDH) is chemically bonded to the surface of an electrode substrate, and a method using the same It relates to an alkaline water electrolysis cell.

Fossil fuels such as natural gas, petroleum, and coal are the most widely used resources, but their reserves are limited and regionally biased, and carbon dioxide, nitrogen oxides, and sulfur oxides produced after combustion are known to be major causes of environmental problems. Hydrogen energy is attracting attention as one of these alternatives to fossil fuels. When hydrogen is used, a very small amount of nitrogen compounds are emitted as pollutants during combustion, so there is less concern about environmental pollution, and there are advantages in the recycling process in which water is generated after combustion. In addition, recently, attempts have been made to store surplus energy in the form of hydrogen by using the high energy storage characteristics of hydrogen energy in connection with new and renewable energies such as sunlight and wind power with irregular power generation.

Hydrogen is different from energy storage technology using batteries in that it can convert and store the unused portion of renewable power in a large-capacity, long-term cycle, and has the advantage of energy diversification and scalability.

On the other hand, the water electrolysis technology, which is a representative hydrogen production technology, is a technology that directly produces hydrogen from water using electric energy, and can produce high-purity hydrogen simply and environmentally. The water electrolysis technique can be divided into alkaline water electrolysis, solid polymer electrolyte water electrolysis, and high-temperature steam electrolysis.

The alkaline water electrolysis method of the above water electrolysis technology is a method with low price and high commercialization potential. It is basically composed of an electrolyte, a separator, and an anode and a cathode, which are electrodes. In the anode and the cathode, the reaction as shown in Scheme 1 below is Happens:

[Scheme 1]

Anode: 4OH ^- → O ₂ + 2H ₂ O + 4e ^-

Cathode: 4H ₂ O + 4e ^- → 2H ₂ + 4OH ^-

The alkaline water electrolysis technology is a commercially proven technology that is suitable for large-capacity hydrogen production and has price competitiveness compared to other technologies, so it is the most popular technology in Korea. It is essential to develop an electrode capable of lowering the overvoltage in the oxygen reaction and having durability.

In the technology related to the development of the electrode constituting the alkaline water electrolysis, the prior art uses a metal active in oxygen and hydrogen generation reaction as an electrode as a plate material, or uses atmospheric pressure or high pressure plasma deposition, electrostatic painting, electrochemical plating , a hydrothermal synthesis method, etc. to coat the catalyst on a desired substrate to construct an electrode.

The electrode produced by the hydrothermal synthesis method and electrostatic coating has poor bonding strength between the substrate and the catalyst, so heat treatment at about 1000° C. is required, repeated coating and heat treatment operations are required, and the electrode produced by plasma deposition and electrochemical plating Silver has the advantage of high binding strength, but a complicated continuous process is required. In addition, there was a problem in that the electrode was rapidly deactivated due to sintering and agglomeration of the metal nanocatalysts during the heat treatment process.

On the other hand, in the renewable energy-linked water electrolysis system, the commercial water electrolysis system to which the prior art is applied increases the resistance in the system during high current operation and repeated on/off operation, and pores due to the hydrogen and oxygen gas generation reaction in the electrode are reduced. Since the electrode activity is reduced due to the collapse phenomenon and durability is lowered, there is a problem that ^{constant current operation must be operated at a low current density within 0.2 A/cm 2 In} the case of Raney Ni, a typical alkaline water electrolysis electrode, electric After alloying of Ni-(Zn,Al) through chemical plating or plasma deposition, etc., Zn, Al, etc. are selectively leached through reaction with a strong alkaline solution to manufacture a porous Ni electrode to increase activity, but on/off There was a problem in that it showed a weakness in durability in repeated operation.

In order to solve the above problems, there is a need to develop an electrode material that has improved durability according to a voltage potential change during on/off repeated operation of a water electrolysis system in an alkaline solution and can operate with high efficiency and high current.

Republic of Korea Patent No. 10-1807287

Technical problem to be achieved by the present invention comprises the steps of preparing a solution containing an electrode substrate and a second metal including a first metal; And by inducing a spontaneous oxidation reaction of the first metal located on the surface of the electrode substrate after immersing the electrode substrate containing the first metal in the solution containing the second metal, the double-layer hydroxide structure on the surface of the electrode substrate forming a catalyst layer including (layered double hydroxide; LDH); To provide a method of manufacturing an electrode comprising a, wherein the catalyst layer is chemically bonded to the surface of the electrode substrate.

Another technical object of the present invention is to provide an alkaline water electrolysis cell including an electrode manufactured by the above manufacturing method.

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. There will be.

In order to achieve the above technical problem, one aspect of the present invention comprises the steps of preparing a solution comprising an electrode substrate and a second metal comprising a first metal; And by inducing a spontaneous oxidation reaction of the first metal located on the surface of the electrode substrate after immersing the electrode substrate containing the first metal in the solution containing the second metal, the double-layer hydroxide structure on the surface of the electrode substrate (layered double hydroxide; LDH) to form a catalyst layer comprising a; and provides a method of manufacturing an electrode comprising, the catalyst layer is chemically bonded to the surface of the electrode substrate.

In one embodiment of the present invention, the first metal may be any one metal selected from the group consisting of low carbon steel, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof.

In one embodiment of the present invention, the second metal may be any one selected from the group consisting of aluminum, chromium, gallium, manganese, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof.

In an embodiment of the present invention, the double-layered hydroxide structure may be represented by the following Chemical Formula 1:

[Formula 1]

[(M ^I ) ³⁺ _x (M ^Ⅱ ) ²⁺ _1-x (OH) ₂ ] ^x+ [A ^n- _x/n ] ^x- zH ₂ O

In the above formula,

M ^I includes any one metal selected from the group consisting of low-carbon steel, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof,

M ^Ⅱ includes any one metal selected from the group consisting of aluminum, chromium, gallium, manganese, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof,

A ^n- is a hydroxide ion (OH ^- ), nitrate ion (NO ^3- ), PO ₄ ^3- , HPO ₄ ^2- , H ₂ PO ^4- , SO ₄ ^2- , CO ₃ ^2- and combinations thereof. Any one anion selected from the group,

x is a number greater than 0 and less than 1,

n is an integer from 1 to 4,

z is a number from 0.1 to 15.

In one embodiment of the present invention, in the step of forming the catalyst layer, the process of inducing the spontaneous oxidation reaction is a method of injecting oxygen into a solution containing a second metal in which an electrode substrate containing a first metal is immersed; It may be performed by any one of a method of applying a corrosion potential, a method of adjusting pH, and a combination thereof.

In an embodiment of the present invention, the method of injecting oxygen may be performed by injecting oxygen so that the amount of dissolved oxygen in the solution becomes saturated within 20 ppm.

In an embodiment of the present invention, the method of applying the corrosion potential may be performed by applying a voltage of -0.5 V to 0.8 V.

In an embodiment of the present invention, the method for adjusting the pH may be performed by adding any one _{of NaOH, HCl, and H 2} SO _{4 .}

In an embodiment of the present invention, in the step of forming the catalyst layer, the pH of the solution including the second metal may be 0 to 8.

In an embodiment of the present invention, in the step of forming the catalyst layer, the thickness of the formed catalyst layer may be 5 nm to 5 μm.

One aspect of the present invention provides an alkaline water electrolysis cell including an electrode manufactured by the above manufacturing method.

The electrode manufactured by the method for manufacturing an electrode of the present invention exists in a phase in which a substrate and a catalyst are combined through an oxidation/reduction chemical reaction.

When the electrode is used as an electrode of an alkaline water electrolysis cell, durability is improved according to a voltage potential change during on/off repeated operation of the water electrolysis system in an alkaline solution. The water electrolysis cell to which the above electrode is applied secures stability against repeated on/off operation and can be linked with intermittent renewable energy such as solar or wind power, and long-term, large-capacity through hydrogen production using surplus power of renewable energy As energy storage, water electrolysis devices can be utilized.

In addition, the electrode of the present invention can increase the cell efficiency by 30% or more by using a small amount compared to the conventional commercial nickel electrode, and high current operation ^{of 2.0 A/cm 2 with high efficiency of 70% to 90% is possible.} It has the advantage of lowering the system cost and lowering the system volume.

Furthermore, the electrode can be used as an electrode in a chloro-alkali process or alkaline fuel cell, which is a similar electrochemical system, in addition to the water electrolysis electrode, and is a catalyst in the syngas production process and environmental water treatment field or as an adsorbent.

The effects of the present invention are not limited to the above effects, but it should be understood to include all effects inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a flowchart of a method of manufacturing an electrode according to an embodiment of the present invention.
2 is a Potential-pH (Pourbaix) diagram of nickel (a) and a Potential-pH (Pourbaix) diagram of iron (b).
3 is an SEM image of the surface of an electrode according to an embodiment of the present invention.
4 is a graph showing a change in pH of a solution in the manufacturing method of an embodiment of the present invention.
5 is an XRD analysis graph of an embodiment of the present invention and a control group.
6 is a graph showing the results of a potential change experiment of an electrolytic cell including an electrode according to an embodiment of the present invention.

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be embodied in several different forms, and thus is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part is said to be “connected (connected, contacted, coupled)” with another part, it is not only “directly connected” but also “indirectly connected” with another member interposed therebetween. "Including cases where In addition, when a part "includes" a certain component, this means that other components may be further provided without excluding other components unless otherwise stated.

The terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In this specification, terms such as "comprises" or "have" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one or more other features It should be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

One aspect of the present invention provides a method of manufacturing an electrode.

1 is a flowchart of a method of manufacturing an electrode according to an embodiment of the present invention.

Referring to FIG. 1 , the method for manufacturing an electrode of the present invention includes preparing an electrode substrate including a first metal and a solution including a second metal (S100); And by inducing a spontaneous oxidation reaction of the first metal located on the surface of the electrode substrate after immersing the electrode substrate containing the first metal in the solution containing the second metal, the double-layer hydroxide structure on the surface of the electrode substrate Forming a catalyst layer containing (layered double hydroxide; LDH) (S200); includes

First, the method of manufacturing an electrode of the present invention includes a step (S100) of preparing an electrode substrate containing a first metal and a solution containing a second metal.

In one embodiment of the present invention, the electrode substrate is a place where the catalyst layer is formed on the surface in the step (S200) of forming a catalyst layer to be described later, and includes a first metal.

The first metal is a metal that can induce a spontaneous oxidation reaction in the step (S200) of forming a catalyst layer to be described later, for example, a metal including a transition metal, for example, low carbon steel, iron, magnesium, cobalt, It may be any one metal selected from the group consisting of copper, nickel, zinc, and combinations thereof, for example, iron (Fe).

The second metal may be included in the form of a divalent metal cation in the solution containing the second metal, and in the step (S200) of forming a catalyst layer to be described later, the first metal in the form of a trivalent metal cation A metal that can be substituted to form a catalyst layer, for example, a metal containing a transition metal, for example, aluminum, chromium, gallium, manganese, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof. It may be any one metal selected from the group, for example, nickel (Ni).

The solvent of the solution containing the second metal is a solvent capable of dissolving the second metal to exist in the form of a divalent metal cation, for example, ultrapure water, glycerol, ethylene glycol, polyethylene glycol, diethylene glycol, tri Ethylene glycol, tetraethylene glycol, formamide, N-methylformamide, dimethyl formamide, dimethyl acetylamide, dimethyl sulfoxide, methanol, acetonitrile, 2-pyrrolidinone, acetamide, acrylamide, N-methylurea, It may be any one selected from the group consisting of urea and combinations thereof, but is not limited thereto.

In one embodiment of the present invention, the pH of the solution containing the second metal may be 0 to 8, for example, 4 to 6.5.

2 is a Potential-pH (Pourbaix) diagram of nickel (a) and a Potential-pH (Pourbaix) diagram of iron (b).

The Pourbaix diagram is a diagram systematized by calculating based on the Nernst relational formula and solubility of metal compounds. It is used to determine the electrochemical conditions of spontaneous corrosion reactions, predict the composition of corrosion reactants, and predict changes in environmental conditions for corrosion prevention. can be used

In one embodiment of the present invention, the Pourbaix diagram may be used to identify the electrochemical condition of a region in which a metal, for example, iron or nickel, becomes a divalent cation. Referring to FIG. 2 , the first metal And when the second metal is iron and nickel, the pH range of the region in which the iron and nickel are divalent cations, that is, the pH range that a solution containing the second metal can have may be 0 to 8. .

Next, the method for manufacturing an electrode of the present invention induces a spontaneous oxidation reaction of the first metal located on the surface of the electrode substrate after immersing the electrode substrate containing the first metal in a solution containing the second metal. Thus, forming a catalyst layer including a layered double hydroxide (LDH) on the surface of the electrode substrate (S200).

In one embodiment of the present invention, the step of forming the catalyst layer on the surface of the electrode substrate (S200) is located on the surface of the electrode substrate after immersing the electrode substrate containing the first metal in a solution containing the second metal. It can be carried out by inducing a spontaneous oxidation reaction of the first metal.

In the process of inducing the spontaneous oxidation reaction of the first metal, oxidation and reduction reactions may occur on the surface of the electrode substrate as shown in Scheme 2 below:

[Scheme 2]

Oxidation:

M ^Ⅰ → (M ^Ⅰ ) ²⁺ + 2e ^-

(M ^Ⅰ ) ²⁺ → (M ^Ⅰ ) ³⁺ + e ^-

Reduction reaction:

O ₂ + 2H ₂ O + 4e ^- → 4OH ^-

In the above formula, M ^I includes any one metal selected from the group consisting of low-carbon steel, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof.

In one embodiment of the present invention, in the process of inducing a spontaneous oxidation reaction of the first metal located on the surface of the electrode substrate, oxygen is injected into a solution containing the second metal in which the electrode substrate containing the first metal is immersed. It can be carried out by any one of a method consisting of a method of corrosive potential, a method of applying a corrosion potential, a method of adjusting pH, and a combination thereof.

In an embodiment of the present invention, the process of inducing the spontaneous oxidation reaction may be performed through a method of injecting oxygen into a solution containing a second metal in which an electrode substrate containing a first metal is immersed.

At this time, by controlling the concentration of the injected oxygen, the reaction rate of the spontaneous oxidation reaction can be controlled, and further, the reaction rate of the oxidation reaction determines the thickness and/or configuration of the catalyst layer formed in the production method of the present invention. can be a factor

The method of injecting oxygen into the solution containing the second metal in which the electrode substrate containing the first metal is immersed may be performed using a method known in the art, for example, an oxygen injection device, The present invention is not limited thereto, and oxygen may be injected so that the dissolved oxygen amount of the solution may be saturated within 20 ppm.

In another embodiment of the present invention, the process of inducing the spontaneous oxidation reaction may be performed through a method of applying a corrosion potential to a solution containing a second metal in which an electrode substrate containing a first metal is immersed.

At this time, by controlling the voltage applied to the solution, the reaction rate of the spontaneous oxidation reaction can be controlled, and further, the reaction rate of the oxidation reaction determines the thickness and/or configuration of the catalyst layer formed in the production method of the present invention. can be a factor

A method of applying a corrosion potential to a solution containing a second metal in which the electrode substrate containing the first metal is immersed may be performed using a method known in the art, for example, a voltage applying device. , but is not limited thereto, and for example, may be performed by applying a voltage of -0.5 V to 0.8 V compared to a standard hydrogen electrode (SHE).

In another embodiment of the present invention, the process of inducing the spontaneous oxidation reaction may be performed through a method of adjusting the pH of a solution containing a second metal in which an electrode substrate containing a first metal is immersed.

A method of adjusting the pH of a solution containing a second metal in which the electrode substrate including the first metal is immersed is a method obvious in the art, for example, any one of _{NaOH, HCl and H 2} SO ₄ It may be carried out by adding, but is not limited thereto.

In one embodiment of the present invention, the pH of the solution is adjusted by adjusting the pH and/or potential for inducing an oxidation reaction to a cation based on the thermodynamic properties (see FIG. 2 ) of the first metal included in the electrode substrate, may lead to corrosion of

At the same time, the second metal cation dissolved in the solution may be deposited on the electrode substrate corroded according to the pH change, thereby forming a double-layered hydroxide structure (LDH).

In an embodiment of the present invention, the adjusted pH may be 0 to 8, and the adjusted potential may be performed by applying a voltage of -0.5 V to 0.8 V compared to a standard hydrogen electrode (SHE).

In the step (S200) of forming the catalyst layer of the method for manufacturing an electrode of the present invention, the electrode substrate containing the first metal is immersed in a solution containing the second metal, and the first electrode substrate is located on the surface of the electrode substrate. When the process of inducing a spontaneous oxidation reaction of the metal is performed, the divalent cation of the second metal and the trivalent cation of the first metal included in the solution may be mixed in the solution. At this time, in the solution phase, a reaction as shown in Scheme 3 below may be performed to form a catalyst layer including a layered double hydroxide (LDH):

[Scheme 3]

(M ^Ⅰ ) ³⁺ + (M ^Ⅱ ) ²⁺ + A ^n- → [(M ^Ⅰ ) ³⁺ _x (M ^Ⅱ ) ²⁺ _1-x (OH) ₂ ] ^x+ [A ^n- _x/n ] ^x- zH ₂ O

In the above formula,

M ^I includes any one metal selected from the group consisting of low-carbon steel, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof,

M ^Ⅱ includes any one metal selected from the group consisting of aluminum, chromium, gallium, manganese, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof,

A ^n- is _{^{OH -, NO 3-, PO 4}} 3-, HPO 4 2-, H 2 PO 4-, SO 4 2-, CO 3 2- , and any of the anions selected from the group consisting of a combination of ego,

x is a number greater than 0 and less than 1,

n is an integer from 1 to 4,

z is a number from 0.1 to 15.

In Scheme 3, A ^n- may be determined according to a chemical added to the solution, and the compound to be added is a compound containing an anion, for example, M ^II SO ₄ , M ^II NO ₃ or M ^II CO ₃ (provided that M ^II is any one metal selected from the group consisting of aluminum, chromium, gallium, manganese, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof), but is not limited thereto it is not

When the reaction as in Reaction Scheme 2 described above proceeds on the surface of the electrode substrate in the solution and the reaction as in Reaction Scheme 3 proceeds at the same time, a catalyst insect in a chemically bonded form is formed on the surface of the electrode substrate of the present invention by oxidation / reduction can be

In an embodiment of the present invention, the double-layered hydroxide structure may be represented by the following Chemical Formula 1:

[Formula 1]

[(M ^I ) ³⁺ _x (M ^Ⅱ ) ²⁺ _1-x (OH) ₂ ] ^x+ [A ^n- _x/n ] ^x- zH ₂ O

In the above formula,

M ^I includes any one metal selected from the group consisting of low-carbon steel, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof,

M ^Ⅱ includes any one metal selected from the group consisting of aluminum, chromium, gallium, manganese, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof,

A ^n- is _{^{OH -, NO 3-, PO 4}} 3-, HPO 4 2-, H 2 PO 4-, SO 4 2-, CO 3 2- , and any of the anions selected from the group consisting of a combination of ego,

x is a number greater than 0 and less than 1,

n is an integer from 1 to 4,

z is a number from 0.1 to 15.

In one embodiment of the present invention, in Formula 1, M ^I may be the first metal of the present invention, and M ^II may be the second metal of the present invention.

In the present specification, the two-dimensional hydroxide structure (LDH) having a two-dimensional structure represented by Formula 1 is a divalent metal cation ^{surrounded by six OH −} in an octahedral form, and some of the divalent metal cations are trivalent It means a hydroxide having a two-dimensional layered structure substituted with a metal cation to have a positive charge on the surface, and the positive charge on the surface of the double-layered hydroxide structure can be offset by ^{anions (A n- ) present between the layered structures.} .

The double-layered hydroxide structure has a very large specific surface area, can easily exchange anion compared to other exchangers, and has applications in various fields such as catalysts, adsorbents, flame retardants, and photocatalysts due to heat stability, electrical and optical properties, etc. possible.

In the electrode of the present invention, a catalyst layer including the double-layered hydroxide structure may be formed, and the catalyst layer is present in a state chemically bonded to the surface of the electrode substrate of the present invention.

Therefore, the electrode having the catalyst layer formed thereon is used in alkaline water electrolysis electrodes, due to the characteristics of the double-layer hydroxide structure for easy mass transfer and ion conduction, it is possible to enable high-efficiency and high-current operation of the water electrolysis stack. , it is possible to show the improvement of durability according to the voltage potential change during repeated on/off operation of the water electrolysis system in an alkaline solution. Therefore, the electrolytic cell to which the electrode is applied can secure stability against repeated on/off operation, thereby enabling connection with intermittent renewable energy such as solar power or wind power.

Furthermore, the electrode of the present invention can be used as an electrode in other electrochemical systems using hydrogen and oxygen evolution as a reaction mechanism, for example, capacitors, fuel cells, caustic soda electrolytic manufacturing, etc. and as a catalyst or adsorbent in the field of environmental water treatment.

In one embodiment of the present invention, in the step of forming the catalyst layer (S200), the thickness of the formed catalyst layer is determined by the concentration of the injected oxygen or the applied voltage in the process of inducing the above-described spontaneous oxidation of the first metal. It may be adjusted according to the range, or may be adjusted according to the concentration of the second metal ion contained in the solution.

In the step of forming the catalyst layer (S200), the thickness of the formed catalyst layer may be 5 nm to 5 μm.

One aspect of the present invention provides an alkaline water electrolysis cell including an electrode manufactured by the manufacturing method described in the above aspect.

In the present specification, alkaline electrolysis is a type of water electrolysis, and is a technique of using an alkaline aqueous solution as an electrolyte and using a separate membrane to separate hydrogen/oxygen. Specifically, in the alkaline water electrolysis method, an ion separation membrane and an electrolyte are injected between the cathode and the anode, which are electrodes, and a constant voltage and current flow through both electrodes to produce hydrogen.

Hydrogen gas and oxygen gas are respectively generated at the cathode and the anode according to the following Reaction Formula 1, and the hydrogen and oxygen gas thus generated are discharged to the outside:

[Scheme 1]

Anode: 4OH ^- → O ₂ + 2H ₂ O + 4e ^-

Cathode: 4H ₂ O + 4e ^- → 2H ₂ + 4OH ^-

^{Specifically, OH −} ions generated at the cathode move through the separation membrane to the anode, and are oxidized at the anode to generate water and oxygen gas.

In one embodiment of the present invention, the electrode for alkaline water electrolysis may be an electrode manufactured in the manufacturing method of the above aspect.

In the prior art related to the alkaline water electrolysis electrode, a metal having an activity for oxygen and hydrogen generation reaction is directly used as an electrode as an electrode, or a catalyst is prepared using atmospheric or high pressure plasma deposition, electrostatic painting, electrochemical plating, hydrothermal synthesis, etc. An electrode was constructed by coating on a desired substrate.

Since the electrode produced by the hydrothermal synthesis method and electrostatic coating has poor bonding strength between the substrate and the catalyst, heat treatment at about 1000° C. is required, repeated coating and heat treatment operations are required, and the electrode produced by plasma deposition and electrochemical plating Silver has the advantage of high binding strength, but a complicated continuous process is required. Also, there was a problem in that the electrode was rapidly deactivated due to sintering and agglomeration of the metal nanocatalysts during the heat treatment process.

On the other hand, in the renewable energy-linked water electrolysis system, the commercial water electrolysis system to which the prior art is applied increases the resistance in the system during high current operation and repeated on/off operation, and pores due to the hydrogen and oxygen gas generation reaction in the electrode are reduced. Since the electrode activity is reduced due to the collapse phenomenon and durability is lowered, there is a problem that ^{constant current operation must be operated at a low current density within 0.2 A/cm 2 In} the case of Raney Ni, a typical alkaline water electrolysis electrode, electric After alloying of Ni-(Zn,Al) through chemical plating or plasma deposition, etc., Zn, Al, etc. are selectively leached through reaction with a strong alkaline solution to manufacture a porous Ni electrode to increase activity, but on/off There was a problem in that it showed a weakness in durability in repeated operation.

The electrode of the present invention includes a double-layered hydroxide structure, and may include a catalyst layer that is chemically bonded to the surface of the electrode substrate. Due to the characteristics of easy mass transfer and ion conduction of the double-layer hydroxide structure, it is possible to enable high-efficiency and high-current operation of the water electrolysis stack, and voltage potential change during on/off repeated operation of the water electrolysis system in an alkaline solution As a result, durability can be improved. Therefore, the water electrolysis cell to which the electrode is applied can secure stability against repeated on/off operation, thereby enabling connection with intermittent renewable energy such as solar or wind power.

Furthermore, the efficiency of the alkaline water electrolysis cell can be increased by 30% or more by using a small amount compared to the conventional commercial nickel electrode, and high-current (about 2.0 A/cm ² ) operation with high efficiency (70% to 90%) is possible. This has the advantage of lowering the stack and system cost and lowering the system volume.

In an embodiment of the present invention, the electrolyte is composed of an aqueous alkaline solution, and the alkaline aqueous solution means an aqueous solution exhibiting basicity. In this case, the alkaline aqueous solution may include a hydroxide of an alkaline metal or alkaline earth metal element. For example, the hydroxide of the alkaline metal may include at least one hydroxide selected from the group consisting of LiOH, NaOH, KOH, RbOH, and CsOH.

The ion separation membrane may be positioned inside the electrolyte to selectively permeate specific ions in the electrolyte. In this case, the ion separation membrane may selectively permeate cations or anions according to the shape of the ionization group attached to the membrane matrix. For example, when the ion separation membrane has an anion group such as ^{-SO 3-} , -COO ^- , -PO ₃ ^2- , -PO ₃ H ^- , -C ₆ H ₄ O ^{- in the membrane backbone} Only positive ions can pass selectively. For example, the ion separation membrane has a cation group such as ^{-NH 3+} , -NRH ²⁺ , -NR ₂ H ⁺ , -NR ³⁺ , -PR ³⁺ , -SR ^{2+ on the membrane backbone.} If present, only negative ions can be selectively passed through.

Example 1. Preparation of Fe-Ni Bilayer Hydroxide Electrode

NiSO ₄ was dissolved in ultrapure water (deionized water), and Fe foam (2 N) was prepared as a solution containing 2 M Ni cations and an electrode substrate. The Fe foam substrate was pre-treated by immersing it in 20 % HCl solution for 10 minutes, and the residue was removed with distilled water.

The electrode substrate was immersed in a solution containing Ni cations, and oxygen was injected at a rate of 150 ccm using an oxygen injection device, and reacted at 50 °C for about 2 hours while maintaining the stirring rate at 500 rpm, Fe A -Ni bilayer hydroxide electrode was prepared. At this time, it was determined whether the double-layer hydroxide electrode was generated according to the pH change in the solution containing Ni cations.

Experimental Example 1. Surface analysis

The surface of the Fe-Ni double-layer hydroxide electrode prepared in Preparation Example 1 was observed using SEM, and the results are shown in FIG. 2 .

Referring to FIG. 2 , it was confirmed that a double-layered hydroxide structure was formed on the surface of the electrode substrate made of Fe.

Experimental Example 2. Measurement of pH change

During the preparation of the Fe-Ni double-layer hydroxide electrode in Preparation Example 1, the change in pH of the solution containing Ni cations with time was measured, and is shown in FIG. 3 .

Referring to FIG. 3 , it can be seen that the pH increases for the initial 2 hours and then decreases, which ^{can be inferred that the OH -} ions disappear due to the formation of the double-layer hydroxide structure, thus, Fe- of Preparation Example 1 It was confirmed that a double-layered hydroxide structure was formed on the Ni double-layered hydroxide electrode.

Experimental Example 3. XRD analysis

The Fe-Ni double layer hydroxide electrode prepared in Preparation Example 1 and the Fe foam substrate as a control were analyzed by XRD, and the results are shown in FIG. 4 .

Referring to FIG. 4, in the Fe-Ni double-layer hydroxide electrode of the present invention, it was confirmed that peaks appeared at 003, 006, 012, and 015 indicating the double-layer hydroxide structure, and it was confirmed that the double-layer hydroxide structure was formed.

Experimental Examples 4-1 to 4-3. Potential fluctuation experiment

The electric potential fluctuation experiment of the alkaline water electrolysis cell including the Fe-Ni double-layer hydroxide electrode prepared in Preparation Example 1 was conducted by changing the voltage at 30-minute intervals under the conditions shown in Table 1 below, and the accelerated durability results were shown. 5 is shown:

Voltage potential (V) drop rate (%) Experimental Example 4-1 0.75 2.28 Experimental Example 4-2 0.5 ↔ 0.75 2.33 Experimental Example 4-3 0.3 ↔ 0.75 1.43

Referring to FIG. 5 , it was confirmed that the durability was improved according to the voltage potential change of the water electrolysis system in the alkaline solution.

The description of the present invention described above is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and likewise components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention.

Claims (11)

preparing a solution including an electrode substrate including a first metal and a second metal; and
After immersing the electrode substrate containing the first metal in the solution containing the second metal, a spontaneous oxidation reaction of the first metal located on the surface of the electrode substrate is induced, and the double-layered hydroxide structure is formed on the surface of the electrode substrate ( forming a catalyst layer including layered double hydroxide (LDH);
A method of manufacturing an electrode comprising a, wherein the catalyst layer is chemically bonded to the surface of the electrode substrate. The method of claim 1,
The first metal is any one metal selected from the group consisting of low carbon steel, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof. The method of claim 1,
The second metal is any one metal selected from the group consisting of aluminum, chromium, gallium, manganese, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof. The method of claim 1,
The method of manufacturing an electrode, characterized in that the double-layer hydroxide structure is represented by the following Chemical Formula 1:
[Formula 1]
[(M ^I ) ³⁺ _x (M ^Ⅱ ) ²⁺ _1-x (OH) ₂ ] ^x+ [A ^n- _x/n ] ^x- zH ₂ O
In the above formula,
M ^I includes any one metal selected from the group consisting of low-carbon steel, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof,
M ^Ⅱ includes any one metal selected from the group consisting of aluminum, chromium, gallium, manganese, iron, magnesium, cobalt, copper, nickel, zinc, and combinations thereof,
A ^n- is _{^{OH -, NO 3-, PO 4}} 3-, HPO 4 2-, H 2 PO 4-, SO 4 2-, CO 3 2- , and any of the anions selected from the group consisting of a combination of ego,
x is a number greater than 0 and less than 1,
n is an integer from 1 to 4,
z is a number from 0.1 to 15. The method of claim 1,
In the step of forming the catalyst layer,
The process of inducing the spontaneous oxidation reaction is a method of injecting oxygen into a solution containing a second metal in which an electrode substrate containing a first metal is immersed, a method of applying a corrosion potential, a method of adjusting pH, and combinations thereof A method of manufacturing an electrode, characterized in that it is carried out by any one of the methods consisting of. 6. The method of claim 5,
The method of injecting oxygen is a method of manufacturing an electrode, characterized in that it is performed by injecting oxygen so that the dissolved oxygen amount of the solution is saturated within 20 ppm. 6. The method of claim 5,
The method of applying the corrosion potential is a method of manufacturing an electrode, characterized in that performed by applying a voltage of -0.5 V to 0.8 V. 6. The method of claim 5,
The method of adjusting the pH is a method of manufacturing an electrode, characterized in that it is performed by adding any one _{of NaOH, HCl and H 2} SO _{4 .} The method of claim 1,
In the step of forming the catalyst layer,
The method of manufacturing an electrode, characterized in that the pH of the solution containing the second metal is 0 to 8. The method of claim 1,
In the step of forming the catalyst layer,
The thickness of the formed catalyst layer is a method of manufacturing an electrode, characterized in that 5 nm to 5 μm. An alkaline water electrolysis cell comprising an electrode manufactured by the method of claim 1 .

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