KR20220128961A - Method for manufacturing electrode for water electrolysis and electrode for water electrolysis therefrom - Google Patents

Abstract

The present invention provides a method for manufacturing a water electrolysis electrode having excellent durability and a water electrolysis electrode manufactured therefrom. The method for manufacturing a water electrolysis electrode of the present invention includes the steps of: forming a coating layer including a metal hydroxide on a metal substrate; and converting the metal hydroxide into a metal oxide.

Description

Method for manufacturing a water electrolytic electrode and a water electrolytic electrode manufactured therefrom

This specification claims the benefit of the filing date of Korean Patent Application No. 10-2021-0033600 filed with the Korean Intellectual Property Office on March 15, 2021, the entire contents of which are included in the present invention.

The present invention relates to a method for manufacturing a water electrolytic electrode and a water electrolytic electrode manufactured therefrom.

The demand for renewable energy is increasing due to the acceleration of global warming caused by the use of carbon-based energy storage devices. In particular, a method for producing hydrogen electrochemically by using electrolysis of water has been extensively studied, and the hydrogen produced here can be used in a fuel cell, a direct combustion engine such as a hydrogen turbine and a co-fired power generation.

Electrochemical water splitting occurs in two reactions: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Ideally, the reaction can proceed when a voltage of 1.23V is applied to water electrolysis. However, in reality, an overvoltage of 1.23V or more must be applied in order to produce hydrogen through water electrolysis due to the effect of surface resistance. Therefore, in order to increase the efficiency of water electrolysis by reducing the cost of electric energy, it is necessary to reduce the overvoltage for water electrolysis. Therefore, a catalyst capable of reducing the overvoltage in the hydrogen generation reaction and the oxygen generation reaction is required, respectively.

The ultimate goal of developing non-precious metal electrode catalysts for water electrolysis is their application to large-scale industrial applications for hydrogen (H ₂ ) production. For industrial use, high current densities (≥ 500 mA/cm2) are required for water separation at 1.8 to 2.4 V.

What is important is to ensure the performance of commercial devices such as proton exchange membrane water electrolyzers (PEMWE) and anion exchange membrane water electrolyzers (AEMWE) under real operating conditions as well as catalyst scale performance. The production of hydrogen gas (H ₂ ) at the cathode in commercial water electrolysis devices is severely limited by the slow reaction kinetics of the oxygen evolution reaction (OER, 4OH → O ₂ + 2H ₂ O + 4e ⁻ ) at the anode. Despite the importance of OER, the high overvoltage of OER still acts as a rate-determining step (RDS) and reduces the efficiency of the water electrolysis reaction.

Therefore, in order to increase energy efficiency, it is necessary to develop a high-efficiency OER electrode catalyst.

Recently, many OER electrode catalysts are composed of non-noble metals with excellent activity such as transition metal sulfide (TMS), transition metal phosphate (TMP), layered double hydroxide (LDH) and transition metal oxide. The reported OER electrochemical catalyst has a very low overvoltage (below 300 mV at 10 mA/cm ² ) with excellent durability, so it is expected that it will soon be used in commercial water electrolysis devices. However, most studies do not report the performance of commercial devices. This is because, unlike catalyst research, there are various variables such as catalyst slurry preparation conditions for electrode fabrication, membrane electrode assembly (MEA) manufacturing conditions, battery operating temperature, electrolyte flow rate, and battery manufacturing pressure.

In general, when manufacturing an electrode or MEA, catalyst synthesis - heat treatment - slurry preparation - coating - drying steps are performed, which are many and complicated, so there are many variables to be controlled, and there is an aspect that changes to key components are not free. Therefore, it is necessary to simplify the electrode manufacturing process to improve process reliability and reduce the electrode manufacturing cost.

In addition, there is still a need for a method such as electrodeposition or corrosion for manufacturing a large-area electrode.

An object of the present invention is to provide a method for manufacturing a water electrolytic electrode having excellent durability and a water electrolytic electrode manufactured therefrom.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

One embodiment of the present invention comprises the steps of forming a coating layer comprising a metal hydroxide on a metal substrate; and converting the metal hydroxide into metal oxide by hot-pressing and heat-treating the metal substrate on which the coating layer is formed.

In addition, an exemplary embodiment of the present invention provides an electrolytic electrode prepared by the above method and including a catalyst layer including a plurality of metal oxide particles.

The method of manufacturing an electrolytic electrode according to an exemplary embodiment of the present invention can simplify the electrode manufacturing process, secure the performance and reliability of the electrode, and reduce the electrode manufacturing cost.

The method for manufacturing a water electrolytic electrode according to an exemplary embodiment of the present invention can provide a water electrolytic electrode having excellent durability.

The method for manufacturing a water electrolytic electrode according to an exemplary embodiment of the present invention may provide a water electrolytic electrode in a simple manner.

The water electrolytic electrode according to an exemplary embodiment of the present invention has excellent durability and can be driven while maintaining performance even at high current density for a long time.

Effects of the present invention are not limited to the above-described effects, and effects not mentioned will be clearly understood by those skilled in the art from the present specification.

1A is a photograph of the water electrolytic electrode prepared in Reference Examples 1 to 4 and a photograph taken using a Hyrox microscope, and FIG. 1B is a photograph taken using a Hyrox microscope of the water electrolytic electrode prepared in Example 1 1C is a photograph of the water electrolytic electrode prepared in Reference Examples 5 to 9 and a photograph taken using a Hyrox microscope, and FIG. 1D is a photograph of the water electrolytic electrode prepared in Examples 3 to 6 and This picture was taken using a Hyrox microscope.
2 is a SEM image of the surface of the Co hydroxide of Preparation Example 1 and the water electrolytic electrodes prepared in Reference Examples 3 and 1;
3 is an XRD pattern of the Co hydroxide of Preparation Example 1 and the water electrolytic electrodes prepared in Reference Examples 3 and 1;
4 is an LSV polarization curve corresponding to the current density with respect to the applied voltage of the electrodes prepared in Reference Example 2, Reference Example 3, and Example 1. FIG.
5 is an LSV polarization curve corresponding to a current density with respect to an applied voltage of the electrode prepared in Example 2. FIG.
6 is an LSV polarization curve corresponding to the current density with respect to the applied voltage of the electrode prepared in Reference Examples 7 to 10 and the electrode using the powder prepared in Preparation Example 2;
7 is an LSV polarization curve corresponding to the current density with respect to the applied voltage of the electrodes prepared in Reference Example 9 and Comparative Example 1. Referring to FIG.
8 is a durability evaluation result of electrodes manufactured in Reference Example 2, Reference Example 3, and Example 1. FIG.
9 is a durability evaluation result of the electrode prepared in Example 2.
10 is a durability evaluation result of the electrode prepared in Reference Examples 7 to 10 and the electrode prepared in Preparation Example 2 using the powder.
11 is a durability evaluation result of electrodes prepared in Reference Example 9 and Comparative Example 1.
12 is an SEM image after durability evaluation of the electrode of Example 1. FIG.

In the present specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

Throughout this specification, when a member is said to be located “on” another member, this includes not only a case in which a member is in contact with another member but also a case in which another member is present between the two members.

Throughout this specification, the unit “part by weight” may mean a ratio of weight between each component.

Throughout this specification, "A and/or B" means "A and B, or A or B."

Hereinafter, the present invention will be described in more detail.

One embodiment of the present invention comprises the steps of forming a coating layer comprising a metal hydroxide on a metal substrate; and converting the metal hydroxide into metal oxide by hot-pressing and heat-treating the metal substrate on which the coating layer is formed. That is, by forming a catalyst layer including a metal oxide on a metal substrate, a water electrolysis electrode including the metal substrate and the catalyst layer may be manufactured.

The method of manufacturing an electrolytic electrode according to an exemplary embodiment of the present invention can simplify the electrode manufacturing process, secure the performance and reliability of the electrode, and reduce the electrode manufacturing cost. In addition, the manufacturing method of the water electrolytic electrode may provide a water electrolytic electrode having excellent durability. In addition, the manufacturing method of the water electrolytic electrode can provide a water electrolytic electrode excellent in durability by a simple method.

Hereinafter, a method of manufacturing an electrolytic electrode according to an exemplary embodiment of the present invention will be described in detail in chronological order.

According to an exemplary embodiment of the present invention, a coated metal substrate is manufactured by forming a coating layer including a metal hydroxide on the metal substrate.

According to an exemplary embodiment of the present invention, the metal substrate may be used as an electrode material in general in the technical field, for example, the metal substrate may be Ni foam, Fe foam, Cu foam, Ag foam and at least one of Ti foam.

According to an exemplary embodiment of the present invention, the metal hydroxide may include a hydroxide containing at least one metal of Cu, Co, Ni, and Mn. Specifically, the metal hydroxide may include at least one of Cu hydroxide, Co hydroxide, Ni hydroxide, and Mn hydroxide, and may include a hydroxide containing two or more metals, such as Cu—Co hydroxide. The metal hydroxide is a precursor that is applied on a metal substrate and serves as a water electrolysis catalyst through a subsequent process, and the type and content thereof may be selected according to the composition of the catalyst to be prepared.

According to an exemplary embodiment of the present invention, the step of forming the coating layer may be performed in various ways depending on the type of the metal hydroxide. When using a particle-shaped metal hydroxide, a slurry containing metal hydroxide particles may be used, or a coating layer containing metal hydroxide may be grown on the surface of the metal substrate by immersing the metal substrate through a corrosion mechanism in a metal hydroxide precursor solution. .

According to an exemplary embodiment of the present invention, forming the coating layer may include, for example, applying a slurry including a metal hydroxide on a metal substrate on one surface of the metal substrate.

According to an exemplary embodiment of the present invention, the slurry including the metal hydroxide may include a binder, a pore former, a conductive material, etc. in addition to the metal hydroxide, and may be prepared by mixing them. Among them, the binder will be described later.

According to an exemplary embodiment of the present invention, based on 100 parts by weight of the slurry, the content of the metal hydroxide may be 10 parts by weight or more and 30 parts by weight or less. When the content of the metal hydroxide is within the above range, it is possible to prepare a slurry having an appropriate viscosity, thereby improving manufacturing efficiency, and effectively increasing durability and quality of the manufactured water electrolytic electrode. On the other hand, the content of the metal hydroxide contained in the slurry may be variously set according to the composition of the catalyst to be prepared.

According to an exemplary embodiment of the present invention, the slurry may further include a binder. The binder may be included so that the metal oxide particles to be formed later can be better combined.

According to an exemplary embodiment of the present invention, the binder may be a polymer compound, and specifically, polytetrafluoroethylene (PTFE), p-phenylenediamine (PDA), polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), natural rubber (SMR), and may include at least one of polyvinyl alcohol (PVA).

According to an exemplary embodiment of the present invention, based on 100 parts by weight of the metal hydroxide, the content of the binder may be 5 parts by weight or more and 15 parts by weight or less. When the binder is included in the slurry in an amount within the above range, there may be an effect of preventing deterioration of the catalyst layer when the water electrolytic electrode is introduced into the cell and driven.

According to an exemplary embodiment of the present invention, the slurry may be applied on one surface of the metal substrate. That is, with respect to the plate-shaped metal substrate, the fluid slurry may be poured onto one surface of the metal substrate and then applied to have a uniform thickness. The coating method is not particularly limited, and may be performed using knife coater coating, spray doctor blade coating, dry coating, or the like.

According to an exemplary embodiment of the present invention, in the slurry, the water electrolytic electrode is 1 mg/cm ² to 100 mg/cm ² , 1 mg/cm ² to 80 mg/cm ² , 1 mg/cm ² to 60 mg/ cm ² , 10 mg/cm ² to 40 mg/cm ² , 15 mg/cm ² to 40 mg/cm ² , 15 mg/cm ² to 35 mg/cm ² , 20 mg/cm ² to 35 mg/cm ² , or 30 mg/cm ² to 35 mg/cm ² It may be applied to be loaded in an amount. When the slurry is applied to have a loading amount within the above range, the produced water electrolytic electrode may have reduced mass transfer resistance under unit cell operating conditions, and may provide sufficient active points, so that hydrogen generation performance may be excellent.

According to an exemplary embodiment of the present invention, the metal hydroxide is converted into a metal oxide by hot pressing the metal substrate coated with the slurry. Specifically, the metal hydroxide may be converted into a metal oxide by hot-pressing the metal substrate coated with the slurry containing the metal hydroxide at a high temperature.

According to an exemplary embodiment of the present invention, the hot pressing may be performed at a temperature of 150 ℃ or more and less than 200 ℃, or 150 ℃ or more and 195 ℃ or less. The hot pressing temperature range may be adjusted according to the type of metal hydroxide. For example, when the metal hydroxide includes Co hydroxide, it may be preferable to perform hot pressing in a temperature range of about 190°C to 195°C. When hot pressing is performed at a temperature within the above range, the metal hydroxide may be oxidized and converted into a metal oxide. In addition, it is possible to prevent the problem that the catalyst layer formed because the hot pressing temperature is too low to be easily detached because it is not adhered to the metal substrate and the problem that the metal hydroxide is not converted to the metal oxide.

According to an exemplary embodiment of the present invention, the hot pressing may be performed for 5 minutes to 150 minutes or 10 minutes to 120 minutes. When the time during which the hot pressing is performed is within the above-described range, the formed catalyst layer may be effectively adhered to the metal substrate.

According to an exemplary embodiment of the present invention, the hot pressing may be performed by applying a load of 100 kg/cm ² to 1,000 kg/cm ² or 130 kg/cm ² to 500 kg/cm ² . When hot pressing is performed with a load within the above range, it is possible to effectively convert a phase from a metal hydroxide to a metal oxide, thereby improving the activity and durability of the prepared catalyst, and preventing the catalyst layer from being detached by an oxygen evolution reaction can be effectively suppressed.

According to an exemplary embodiment of the present invention, after hot-pressing the metal substrate on which the coating layer is formed, heat treatment is performed. The heat treatment may be performed by means used in the art, for example, the heat treatment may be performed using a furnace. The heat treatment may be performed at a temperature of 200 °C to 350 °C. By performing the heat treatment at a temperature within the above range, it is possible to stably convert a metal hydroxide that is not completely converted to a metal oxide into a metal oxide after performing hot pressing. Through this, it is possible to effectively improve the activity and durability of the manufactured water electrolytic electrode. In addition, when the binder is included in the slurry, adhesion between the metal oxide catalysts may be improved by stabilizing the binder through the heat treatment, thereby increasing the performance of the water electrolytic electrode.

According to an exemplary embodiment of the present invention, the heat treatment may be performed for 1 hour to 5 hours. When the heat treatment is performed for a time within the above range, it is possible to stably convert a metal hydroxide that is not completely converted to a metal oxide into a metal oxide after performing hot pressing. In addition, when the binder is included in the slurry, the binder can be effectively stabilized through the heat treatment.

According to an exemplary embodiment of the present invention, the heat treatment may include performing additional hot pressing on the metal substrate on which the hot-pressed coating layer is formed. That is, instead of using a furnace as the heat treatment, it may be performed through hot pressing. By performing the heat treatment by additional hot pressing, the adhesion between the catalyst layer including the metal oxide converted from the metal hydroxide and the metal substrate may be improved, thereby further improving the durability of the manufactured water electrolytic electrode.

According to an exemplary embodiment of the present invention, the additional hot pressing may be performed at a temperature of 200 °C to 350 °C, for example, 250 °C. When additional hot pressing is performed at a temperature within the above range, the metal hydroxide that is not converted to the metal oxide can be stably converted to the metal oxide, and the formed catalyst layer can be effectively adhered to the metal substrate.

According to an exemplary embodiment of the present invention, the additional hot pressing may be performed by applying a load of 1,000 kg/cm ² to 6,000 kg/cm ² . When additional hot pressing is performed with a load within the above range, the adhesion between the catalyst layer including the metal oxide converted from the metal hydroxide and the metal substrate may be improved, thereby further improving the durability of the manufactured water electrolytic electrode.

According to an exemplary embodiment of the present invention, the additional hot pressing may be performed for 1 hour to 5 hours. When additional hot pressing is performed for a time within the above range, the unconverted metal hydroxide can be stably converted into a metal oxide, and adhesion between the catalyst layer including the converted metal oxide and the metal substrate can be improved.

According to an exemplary embodiment of the present invention, the additional hot pressing may be performed at a higher temperature and a higher load than hot pressing. By additionally performing hot pressing under harsher conditions, the metal hydroxide remaining without being converted to oxide can be converted to oxide, and the formed catalyst layer can be effectively adhered to the metal substrate to improve the durability of the electrolytic electrode. .

An exemplary embodiment of the present invention provides a water electrolysis electrode manufactured by the above method and including a catalyst layer including a plurality of metal oxide particles.

The water electrolytic electrode according to an exemplary embodiment of the present invention has excellent durability and can be driven while maintaining performance even at high current density for a long time.

According to an exemplary embodiment of the present invention, the electrolytic electrode includes a catalyst layer including a plurality of metal oxide particles. Specifically, the electrolytic electrode may include a metal substrate and a catalyst layer provided on one surface of the metal substrate, and the catalyst layer may include a plurality of metal oxide particles.

In the manufacturing process of the electrolytic electrode, in the hot pressing process, the metal hydroxide may be oxidized and converted to a metal oxide to form particles. Metal hydroxides dispersed in the slurry may aggregate to form clusters while being converted into metal oxides according to a hot pressing process, thereby forming metal oxide particles.

According to an exemplary embodiment of the present invention, the plurality of metal oxide particles may be individually separated and included in the catalyst layer, but some of the metal oxide particles have a necked structure. The necking may refer to a shape in which one particle is connected to another particle in a bridge form. By having the necking structure, the performance and durability of the water electrolytic electrode may be improved.

According to an exemplary embodiment of the present invention, the electrolytic electrode may have a relatively large area. For example, the water electrolytic electrode may have a large area of about 70 cm ² or more and have excellent long-term durability.

Hereinafter, examples will be given to describe the present invention in detail. However, the embodiments according to the present invention may be modified in various other forms, and the scope of the present invention is not to be construed as being limited to the embodiments described below. The embodiments of the present specification are provided to more completely explain the present invention to those of ordinary skill in the art.

Example

Preparation Example 1 (Preparation of Co hydroxide)

Co(NO ₃ ) ₂ ·6H ₂ O(Sigma Aldrich) 100 mM was added to 4 L of distilled water and dissolved for 30 minutes, followed by co-precipitation using ammonia solution (NH ₄ OH, 28-30%). The pH of the solution was fixed at 9.5, and the ammonia solution was injected at a rate of 5 ml/min. After co-precipitation, the precursor solution was stirred for 3 hours and aged for 1 hour for stabilization. After the stabilization process is completed, the precipitate is separated from the solution through a centrifuge (HERMLE, X36HK), rapidly cooled using liquid nitrogen, and freeze-dried at -95 ° C. for 24 hours to prepare Co hydroxide (Co(OH) ₂ ) did.

Preparation Example 2 (Preparation of Cu—Co hydroxide)

In 4 L of distilled water, CuSO ₄ ·5H ₂ O (Sigma Aldrich) 100 mM and Co(NO ₃ ) ₂ ·6H ₂ O (Sigma Aldrich) 100 mM were added and dissolved for 30 minutes, followed by an ammonia solution (NH ₄ OH, 28-30%) was used for co-precipitation. The pH of the solution was fixed at 9.5, and the ammonia solution was injected at a rate of 5 ml/min. After co-precipitation, the precursor solution was stirred for 3 hours and aged for 1 hour for stabilization. After the stabilization process was completed, the precipitate was separated from the solution through a centrifuge (HERMLE, X36HK), rapidly cooled using liquid nitrogen, and freeze-dried at -95 ° C. for 24 hours to prepare Cu—Co hydroxide.

Use of Co hydroxide

Reference Example 1

A slurry was prepared by mixing the Co hydroxide prepared in Preparation Example 1, PTFE and deionized water (DI water) as a binder. At this time, based on 100 parts by weight of the slurry, the content of Co hydroxide was about 18.9 parts by weight. In addition, based on 100 parts by weight of Co hydroxide, the content of the binder was 6 parts by weight.

The slurry was applied on one side of a nickel foam having a size of 7.065 cm ² . The nickel foam coated with the slurry was subjected to hot pressing by applying a load of 500 kg/cm ² at a temperature of 190° C. for 10 minutes to prepare a water electrolytic electrode having a loading amount of 15.7 mg/cm ² .

Reference Example 2

In Reference Example 1, a water electrolytic electrode was manufactured in the same manner as in Reference Example 1, except that hot pressing was performed for 120 minutes and a water electrolytic electrode having a loading amount of 14.68 mg/cm ² was prepared.

Reference Example 3

In Reference Example 1, the content of the binder was adjusted to 10 parts by weight based on 100 parts by weight of Co hydroxide, and the same method as in Reference Example 1, except that a water electrolytic electrode having a loading amount of 17.55 mg/cm ² was prepared. A water electrolytic electrode was prepared.

Reference Example 4

In Reference Example 1, the content of the binder is adjusted to 10 parts by weight based on 100 parts by weight of Co hydroxide, using a nickel foam having a size of 78.5 cm ² , and performing hot pressing by applying a load of 130 kg/cm ² Loading A water electrolytic electrode was prepared in the same manner as in Example 1, except that a water electrolytic electrode having an amount of 24.8 mg/cm ² was prepared.

Reference Example 1 Reference Example 2 Reference Example 3 Reference Example 4 Size of Nickel Foam (cm ² ) 7.065 7.065 7.065 78.5 Binder content (parts by weight) 6 6 10 10 hot pressing Temperature (℃) 190 190 190 190 time (minutes) 10 120 10 10 load (kg/cm ² ) 500 500 500 130 Loading amount (mg/cm ² ) 15.7 14.68 17.55 24.8

In Table 1, the content of the binder is based on 100 parts by weight of the metal hydroxide (parts by weight).

Example 1

A slurry was prepared by mixing the Co hydroxide prepared in Preparation Example 1, PTFE and deionized water (DI water) as a binder. At this time, based on 100 parts by weight of the slurry, the content of Co hydroxide was about 18.9 parts by weight. In addition, the content of the binder was 10 parts by weight based on 100 parts by weight of the Co hydroxide.

The slurry was applied on one side of a nickel foam having a size of 7.065 cm ² . Hot pressing was performed by applying a load of 500 kg/cm ² to the nickel foam coated with the slurry at a temperature of 190° C. for 10 minutes.

Thereafter, an additional heat treatment was performed at a temperature of 250° C. for 3 hours to prepare a water electrolytic electrode having a loading amount of 17.54 mg/cm ² .

Example 2

The slurry prepared in Example 1 was prepared. The slurry was applied on one side of a nickel foam having a size of 78.5 cm ² . Hot pressing was performed by applying a load of 130 kg/cm ² for 10 minutes at a temperature of 190° C. to the nickel foam coated with the slurry.

Thereafter, heat treatment was additionally performed at a temperature of 250° C. for 3 hours to prepare a water electrolytic electrode having a loading amount of 24.8 mg/cm ² .

Example 1 Example 2 Size of Nickel Foam (cm ² ) 7.065 78.5 Binder content (parts by weight) 10 10 hot pressing Temperature (℃) 190 190 time (minutes) 10 10 Load (Kg/cm ² ) 500 130 heat treatment Temperature (℃) 250 250 time (minutes) 180 180 Loading amount (mg/cm ² ) 17.54 24.8

In Table 2, the content of the binder is based on 100 parts by weight of the metal hydroxide (parts by weight).

Using Cu-Co hydroxide

Reference Example 5 (without binder)

A slurry was prepared by mixing Cu—Co hydroxide prepared in Preparation Example 2 and deionized water (DI water). At this time, based on 100 parts by weight of the slurry, the content of Cu—Co hydroxide was about 28.6 parts by weight.

The slurry was applied on one side of a nickel foam having a size of 7.065 cm ² . Hot pressing was performed by applying a load of 150 kg/cm ² to the nickel foam coated with the slurry at a temperature of 150° C. for 120 minutes to prepare a water electrolytic electrode having a loading amount of 22.7 mg/cm ² .

Reference Example 6

A slurry was prepared by mixing the Cu—Co hydroxide prepared in Preparation Example 2, PTFE and deionized water (DI water) as a binder. At this time, based on 100 parts by weight of the slurry, the content of Cu—Co hydroxide was about 18.9 parts by weight. In addition, the content of the binder was 6 parts by weight based on 100 parts by weight of Cu—Co hydroxide.

The slurry was applied on one side of a nickel foam having a size of 7.065 cm ² . The nickel foam coated with the slurry was subjected to hot pressing by applying a load of 150 kg/cm ² at a temperature of 190° C. for 10 minutes to prepare a water electrolytic electrode having a loading amount of 19.25 mg/cm ² .

Reference Example 7

In Reference Example 6, the water electrolytic electrode was performed in the same manner as in Reference Example 6, except that the water electrolytic electrode having a loading amount of 30.51 mg/cm ² was manufactured by performing hot pressing by applying a load of 500 kg/cm ² . was prepared.

Reference Example 8

In Reference Example 6, the water electrolysis electrode was performed in the same manner as in Reference Example 6, except that a load of 500 kg/cm ² was applied and hot pressing was performed to prepare a water electrolytic electrode having a loading amount of 17.21 mg/cm ² . was prepared.

Reference Example 9

In the same manner as in Reference Example 6, except that in Reference Example 6, a water electrolytic electrode having a loading amount of 17.46 mg/cm ² was prepared by hot pressing by applying a load of 500 kg/cm ² for 120 minutes. A water electrolytic electrode was prepared.

Reference Example 10

In Reference Example 9, in the same manner as in Reference Example 6, except that a water electrolytic electrode having a loading amount of 17.46 mg/cm ² was prepared by performing hot pressing by applying a load of 1,000 kg/cm ² for 120 minutes. A water electrolytic electrode was prepared.

Reference example
5 Reference example
6 Reference example
7 Reference example
8 Reference example
9 Reference example
10 Size of Nickel Foam (cm ² ) 7.065 7.065 7.065 7.065 7.065 7.065 Binder content (parts by weight) - 6 10 10 10 10 hot pressing Temperature (℃) 150 190 190 190 190 190 time (minutes) 120 10 10 10 120 120 Load (Kg/cm ² ) 150 150 500 500 500 1,000 Loading amount (mg/cm ² ) 22.7 19.25 30.51 17.21 17.46 17.46

In Table 3, the content of the binder is based on 100 parts by weight of the metal hydroxide (parts by weight).

Example 3

The slurry prepared in Reference Example 6 was prepared. The slurry was applied on one side of a nickel foam having a size of 7.065 cm ² . Hot pressing was performed by applying a load of 150 kg/cm ² for 10 minutes at a temperature of 190° C. to the nickel foam coated with the slurry.

Thereafter, heat treatment was additionally performed at a temperature of 250° C. for 2 hours to prepare a water electrolytic electrode having a loading amount of 17.54 mg/cm ² .

Example 4

In Reference Example 6, a slurry was prepared in the same manner as in Reference Example 6, except that the content of the binder was adjusted to 10 parts by weight based on 100 parts by weight of Cu—Co hydroxide. The slurry was applied on one side of a nickel foam having a size of 7.065 cm ² . Hot pressing was performed by applying a load of 500 kg/cm ² to the nickel foam coated with the slurry at a temperature of 190° C. for 10 minutes.

Thereafter, additional hot pressing was performed by applying a load of 5,600 kg/cm ² at a temperature of 250° C. for 180 minutes to prepare a water electrolytic electrode having a loading amount of 17.68 mg/cm ² .

Example 5

The slurry prepared in Reference Example 6 was prepared. The slurry was applied on one side of a nickel foam having a size of 78.5 cm ² . Hot pressing was performed by applying a load of 130 kg/cm ² for 10 minutes at a temperature of 190° C. to the nickel foam coated with the slurry.

Thereafter, additional hot pressing was performed by applying a load of 5,600 kg/cm ² at a temperature of 250° C. for 180 minutes to prepare a water electrolytic electrode having a loading amount of 23.15 mg/cm ² .

Example 6

The slurry prepared in Example 4 was prepared. The slurry was applied on one side of a nickel foam having a size of 78.5 cm ² . Hot pressing was performed by applying a load of 130 kg/cm ² for 10 minutes at a temperature of 190° C. to the nickel foam coated with the slurry.

Thereafter, additional hot pressing was performed by applying a load of 5,600 kg/cm ² at a temperature of 250° C. for 180 minutes to prepare a water electrolytic electrode having a loading amount of 23.88 mg/cm ² .

Example 3 Example 4 Example 5 Example 6 Size of Nickel Foam (cm ² ) 7.065 7.065 78.5 78.5 Binder content (parts by weight) 6 10 6 10 hot pressing Temperature (℃) 190 190 190 190 time (minutes) 10 10 10 10 Load (Kg/cm ² ) 150 500 130 130 heat treatment Temperature (℃) 250 - - - time (minutes) 120 - - - additional
hot pressing Temperature (℃) - 250 250 250 time (minutes) - 180 180 180 Load (Kg/cm ² ) - 5,600 5,600 5,600 Loading amount (mg/cm ² ) 17.54 17.68 23.15 23.88

In Table 4, the content of the binder is based on 100 parts by weight of the metal hydroxide (parts by weight).

Comparative Example 1

A Cu—Co oxide catalyst electrode was prepared according to the following method.

The Cu—Co hydroxide powder prepared in Preparation Example 2 was prepared. Thereafter, Cu-Co hydroxide powder was pulverized using a mortar and bowl, and then heat treatment was performed at 300 °C for 4 hours at a temperature increase rate of 5 °C/min in an air atmosphere to synthesize Cu-Co oxide.

A slurry was prepared by mixing the Cu-Co oxide prepared above, PTFE and deionized water (DI water) as a binder. At this time, based on 100 parts by weight of the slurry, the content of Cu-Co oxide was about 18.9 parts by weight. In addition, the content of the binder was 6 parts by weight based on 100 parts by weight of the Cu—Co oxide.

The slurry was applied on one side of a nickel foam having a size of 7.065 cm ² . Hot pressing was performed by applying a load of 100 kg/cm ² to the nickel foam coated with the slurry at a temperature of 250 ° C. for 10 minutes, and heat treatment was performed at 350 ° C. for 1 hour to prepare a Cu—Co oxide catalyst electrode.

Experimental Example 1: Observation of the appearance of the water electrolytic electrode

1A is a photograph of the water electrolytic electrode prepared in Reference Examples 1 to 4 and a photograph taken using a Hyrox microscope, and FIG. 1B is a photograph taken using a Hyrox microscope of the water electrolytic electrode prepared in Example 1 1C is a photograph of the water electrolytic electrode prepared in Reference Examples 5 to 9 and a photograph taken using a Hyrox microscope, and FIG. 1D is a photograph of the water electrolytic electrode prepared in Examples 3 to 6 and This picture was taken using a Hyrox microscope.

Referring to FIGS. 1A to 1D , in the case of the electrolytic electrodes prepared in Examples 1 and 3 to 6 of the present invention, it can be seen that the catalyst layer is uniformly formed.

Experimental Example 2: Observation of the microstructure of the water electrolytic electrode

Images were taken of the Co hydroxide of Preparation Example 1 and the surfaces of the aqueous electrolytic electrodes prepared in Reference Examples 3 and 1 using a scanning electron microscope (SEM).

FIG. 2 shows surface SEM images of the Co hydroxide of Preparation Example 1 and the water electrolytic electrodes prepared in Reference Examples 3 and 1, respectively.

Referring to FIG. 2, it was confirmed that Co hydroxide formed into nanowalls with a size of about 300 um was changed to Co oxide in the form of particles with a size of several tens of um through hot pressing and heat treatment, and necking was formed between Co oxides.

Experimental Example 3: XRD analysis of water electrolytic electrode

X-ray diffraction analysis (XRD) of the Co hydroxide of Preparation Example 1 and the aqueous electrolytic electrodes prepared in Reference Examples 3 and 1 was performed.

FIG. 3 shows XRD patterns of the Co hydroxide of Preparation Example 1 and the water electrolytic electrodes prepared in Reference Examples 3 and 1.

Referring to FIG. 3 , the α-Co(OH) ₂ peak observed in the Co hydroxide of Preparation Example 1 disappears after performing hot pressing in Reference Example 3, and a Co ₃ O ₄ peak is formed instead, and about 19° β-Co(OH) ₂ It can be seen that a peak is formed. That is, it can be confirmed that the Co hydroxide is generally converted to Co oxide or the crystal structure is changed by the hot pressing process. On the other hand, in the electrolytic electrode of Example 1 in which both hot pressing and heat treatment were performed, the β-Co(OH) ₂ peak also disappeared, confirming that Co hydroxide was completely converted into Co oxide.

Experimental Example 4: Characteristic evaluation of water electrolytic electrode

The water electrolytic electrode prepared in Examples 2 to 5, 10 to 12, and 17, the electrode of Comparative Example 1, and the specimen of Reference Example 1 were used as an anode, respectively, and coated with a microporous carbon layer (CeTech Co., Ltd.). Pt/C prepared so as to have a loading amount of Pt of about 1.0 ± 0.05 mg/cm ² along with a Nafion binder (40 wt.%, HISPEC 4000, Johnson Matthey) on a carbon cloth was used as a cathode. A cell was constructed with the anode and cathode, an anion exchange membrane (AEM, X37-50 Grade T, Dioxide Materials), a porous transport layer (PTL, Ti felt, Bekaert), a current collector (stainless steel), and an electrolyte (0.1 M KOH). .

In the cell configured as described above, a polarization curve was derived by applying a voltage in the range of 1.3 V to 1.9 V using a potentiostat using a linear scanning potential (LSV) at a scanning rate of 1 mV/s.

4 shows the LSV polarization curves corresponding to the current density with respect to the applied voltage of the electrodes prepared in Reference Example 2, Reference Example 3, and Example 1, and FIG. 5 shows the applied voltage of the electrodes prepared in Example 2 The LSV polarization curve corresponding to the current density for 7, the LSV polarization curve corresponding to the current density with respect to the applied voltage of the electrodes prepared in Reference Example 9 and Comparative Example 1 is shown in FIG.

Experimental Example 5: Stability evaluation of water electrolytic electrode

In the cell constructed in Experimental Example 4, durability was evaluated for 80 hours, 200 hours, or 1000 hours at a constant current density of 500 mA/cm ² .

8 shows the durability evaluation results of the electrodes prepared in Reference Example 2, Reference Example 3 and Example 1, FIG. 9 shows the durability evaluation results of the electrodes prepared in Example 2, and FIG. 10 shows Reference Example 7 to the electrode prepared in Reference Example 10 and the electrode prepared by using the powder of Preparation Example 2 were shown, and the durability evaluation result of the electrode prepared in Reference Example 9 and Comparative Example 1 is shown in FIG. 11 .

Referring to FIG. 8 , the electrode of Example 1 exhibits only an increase in cell voltage of less than 0.1 V even after 80 hours of driving, confirming that the electrode has excellent durability.

Referring to FIG. 9 , the electrode of Example 2 is a large-area electrode and a graph of a form in which the cell voltage hardly rises even after a long-term operation of 1000 hours can be confirmed. can

Referring to FIG. 10 , when the hot-pressing time is short, the metal hydroxide is not completely oxidized, and it can be seen that the performance of the manufactured electrode is inferior.

Referring to FIG. 11 , it can be seen that the water electrolytic electrode of Comparative Example 1 corresponding to the prior art has inferior durability as the cell voltage rises rapidly immediately after starting the driving, whereas the water electrolytic electrode of Reference Example 9 has 200 It was confirmed that the cell voltage slightly increased to an amount less than 0.1 V even with time driving.

In addition, the electrode of Example 1 was evaluated for durability for 1000 hours at a current density of 500 mA/cm ² , and then an SEM image was taken to observe the electrode surface.

12 shows an SEM image of the electrode of Example 1 after durability evaluation. Referring to FIG. 12 , although some cracks are formed on the surface after the durability evaluation, it can be confirmed that the microstructure is maintained without greatly collapsing.

In the above, although the present invention has been described by way of limited examples, the present invention is not limited thereto, and the technical idea of the present invention and patents to be described below by those of ordinary skill in the art to which the present invention pertains It goes without saying that various modifications and variations are possible within the scope of equivalents of the claims.

Claims (15)

forming a coating layer including a metal hydroxide on a metal substrate; and
The method of manufacturing an electrolytic electrode comprising a; hot-pressing and heat-treating the metal substrate on which the coating layer is formed to convert the metal hydroxide into a metal oxide.
According to claim 1,
The metal substrate is a method of manufacturing a water electrolytic electrode comprising at least one of Ni foam, Fe foam, Cu foam, Ag foam, and Ti foam.
According to claim 1,
The metal hydroxide is a method of manufacturing a water electrolytic electrode comprising a hydroxide containing at least one metal of Cu, Co, Ni, and Mn.
According to claim 1,
The step of forming the coating layer,
The method of manufacturing a water electrolytic electrode comprising a; applying a slurry containing the metal hydroxide on one surface of the metal substrate.
5. The method of claim 4,
Based on 100 parts by weight of the slurry, the content of the metal hydroxide is 10 parts by weight or more and 30 parts by weight or less.
5. The method of claim 4,
The slurry further comprises a binder,
Based on 100 parts by weight of the metal hydroxide, the content of the binder is 5 parts by weight or more and 15 parts by weight or less.
5. The method of claim 4,
The slurry is applied so that the water electrolytic electrode is loaded in an amount of 1 mg/cm ² to 100 mg/cm ² A method of manufacturing a water electrolytic electrode.
According to claim 1,
The hot pressing is a method of manufacturing a water electrolytic electrode that is performed at a temperature of 150 ℃ or more and less than 200 ℃.
According to claim 1,
The hot pressing is a method of manufacturing a water electrolytic electrode that is performed for 5 minutes to 150 minutes.
According to claim 1,
The hot pressing is 100 kg/cm ² to 1,000 kg/cm ² A method of manufacturing a water electrolytic electrode that is performed by applying a load.
According to claim 1,
The heat treatment is a method of manufacturing a water electrolytic electrode that is performed at a temperature of 200 ℃ to 350 ℃.
According to claim 1,
The method of manufacturing a water electrolytic electrode wherein the heat treatment is performed for 1 hour to 5 hours.
According to claim 1,
The heat treatment is
A method of manufacturing a water electrolytic electrode comprising performing additional hot pressing on a metal substrate having a hot-pressed coating layer formed thereon.
14. The method of claim 13,
The additional hot pressing is 1,000 kg/cm ² to 6,000 kg/cm ² A method of manufacturing a water electrolytic electrode that is performed by applying a load.
It is prepared by the method according to claim 1,
A water electrolytic electrode comprising a catalyst layer including a plurality of metal oxide particles.

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