KR20210063678A - Electrode laminate for redution electrode, membrane electrode assembly comprising same and method of preparing same - Google Patents

Abstract

The present invention relates to an electrode laminate including: a porous current collector; and a catalyst layer formed on the porous current collector and including a conductive material, wherein the porous current collector has a mesh form. The electrode laminate, a membrane electrode assembly including the same, and a method for manufacturing the same of the present invention can save manufacturing time by directly coating a conductive material on the porous current collector by electroplating without a need to separately cast an electrode to manufacture the membrane electrode assembly.

Description

An electrode laminate for a reduction electrode, a membrane electrode assembly comprising the same, and a method for manufacturing the same {ELECTRODE LAMINATE FOR REDUTION ELECTRODE, MEMBRANE ELECTRODE ASSEMBLY COMPRISING SAME AND METHOD OF PREPARING SAME}

The present invention relates to an electrode laminate for a reduction electrode, a membrane electrode assembly including the same, and a method for manufacturing the same, and more particularly, to a porous current collector; It is formed on the porous current collector, and includes a catalyst layer comprising a conductive material, wherein the porous current collector is a mesh type electrode laminate for a reduction electrode, a membrane electrode assembly including the same, and a manufacturing method thereof.

_{CO 2} generated while using fossil fuels is well known as the main culprit of greenhouse gases that increase the average temperature of the earth, and this causes various environmental problems due to global warming and climate change. In addition, the world is suffering 1.2 trillion dollars of damage every year due to climate change, and Korea is also seeing an economic loss of 11.5 trillion won due to natural disasters in the last 10 years. In addition, more than 5 million deaths are caused by climate change every year, and by 2030, 3.9 billion people are expected to face water scarcity. Therefore, _{the development of CO 2} separation and storage technology is being actively carried out, and ideally, carbon resource conversion technology such as a technology for producing fuel or chemical raw materials by converting _{CO 2 is in the spotlight.} Using CO ₂ as a raw material and securing a compound raw material that replaces fossil fuels is a future technology with great environmental, economic, and industrial effects, and it can save energy consumption for _{CO 2 separation and treatment.}

The technology of synthesizing chemical raw materials sustainably from water and carbon dioxide using sunlight as an energy source is a clean technology that stores solar energy as chemical energy through photoelectrochemical conversion, and hydrogen, CO (C1 compound), C ₂ H _{Gas chemical raw materials such as 4} (C2 compound) can be produced. In order for the endothermic reaction to proceed thermodynamically, energy must be supplied from the outside. At this time, the required energy can be supplied from sunlight to manufacture high value-added compounds. Since water and carbon dioxide are very stable chemicals, all reactions that decompose water to produce hydrogen and oxygen or reduce carbon dioxide _{to produce compounds such as CO, CH 4} , and C ₂ H ₄ are all endothermic reactions that produce water and carbon dioxide. Through the development of a catalytic material for conversion, the energy consumed for conversion can be reduced, and the efficiency of solar fuel/raw material conversion can be improved.

These technologies are advantageous for future commercialization based on materials with abundant reserves and low supply prices. In nature, plants and bacteria absorb light and combine water and carbon dioxide to convert photosynthesis into sugar, a biological fuel. However, photovoltaic chemical raw material synthesis is a technology that mimics this. Photosynthesis in nature consists of a photoreaction accompanied by absorption of sunlight and a dark reaction in which carbon is fixed thereafter. Modeled after this, a step of absorbing light through a solar cell, a step of decomposing water by the generated electrons, and excitation A lot of research is in progress on realizing a solar fuel/raw material conversion device consisting of a catalytic reaction step in which the converted electrons reduce carbon dioxide.

In particular, the electrochemical unit cell structure, in which the water decomposition step and the carbon dioxide reduction reaction are performed, has a catalyst electrode layer (Catalyst Electrode) in which an electrochemical reaction occurs on both sides of the membrane centering on a polymer electrolyte membrane (Polymer Electrolyte Membrane) through which hydrogen ions move. Membrane Electrode Assembly (MEA) to which the layer) is attached, the gas diffusion layer (GDL) that evenly distributes the reaction gases and transmits the generated electric energy, airtightness of the reaction gases and cooling water and a gasket and a fastening mechanism for maintaining an appropriate fastening pressure, and a bipolar plate for moving reactive gases and cooling water. At the anode, water is supplied and reacts on the electrocatalyst to generate oxygen, hydrogen ions and electrons. At the cathode, hydrogen ions passing through the polymer membrane combine with electrons _{to reduce CO 2} to CO.

Anode: H ₂ O → 1/2O ₂ + 2H ⁺ + 2e ^-

Cathode: CO ₂ + 2H ⁺ → CO + H ₂ O

Such a membrane electrode assembly is mainly formed using a decal method. In the decal method, an electrode paste in which a catalyst material, a proton conductive binder, and a solvent are mixed is coated on a Teflon sheet, and then the catalyst layer is transferred to the conductive electrolyte membrane by thermal fusion. However, this decal method has the biggest drawback in that the catalyst material is not distributed in a uniform thickness on the surface when it is coated, so that the utilization rate of the catalyst is reduced and the performance is deteriorated. In addition, since the secondary thermal fusion is required, the process may be complicated and the interfacial formation may be discontinuously formed as a disadvantage.

The present invention is to solve the problems of the prior art as described above, and an object of the present invention is to directly coat a conductive material on a porous current collector by electroplating without the need to separately cast an electrode to prepare a membrane electrode assembly. To provide a sieve, a membrane electrode assembly including the same, and a method for manufacturing the same.

Another object of the present invention is _{to provide an electrode laminate capable of reducing CO 2} due to high reactivity with _{carbon dioxide (CO 2} ), a membrane electrode assembly including the same, and a method for manufacturing the same.

According to one aspect of the present invention, a porous current collector; A catalyst layer formed on the porous current collector and including a conductive material; and, wherein the porous current collector is in the form of a mesh, is provided.

The porous current collector may include nickel.

The catalyst layer may be formed on one surface of the porous current collector.

The thickness of the porous current collector may be 1 to 500 μm.

The conductive material is silver, platinum, tin, copper, gold, platinum, palladium, nickel, indium, aluminum, iron, rhodium, ruthenium, osmium, cobalt, molybdenum, zinc, vanadium, tungsten, titanium, manganese, chromium, and these It may include one or more selected from the group consisting of alloys.

The conductive material may include silver.

The thickness of the catalyst layer may be 1 to 50 μm.

The electrode laminate may be for use as a carbon dioxide reduction electrode.

According to another aspect of the present invention, the positive electrode including the electrode stack; cathode; and an electrolyte membrane between the positive electrode and the negative electrode.

The electrolyte membrane may include Nafion.

According to another aspect of the present invention, any one electronic component selected from the group consisting of a water decomposition device, a fuel cell, a photoelectric conversion device, and a carbon dioxide reduction device including the membrane electrode assembly is provided.

According to another aspect of the present invention, (a) preparing a porous current collector; and (b) forming a catalyst layer including a conductive material by electroplating a conductive material on the porous current collector to prepare an electrode laminate including a porous current collector/catalyst layer; There is provided a method for manufacturing an electrode laminate, which is in the form of a mesh.

Step (b) is (b-1) impregnating the porous current collector in a plating solution; and (b-2) applying an electric current to the plating solution impregnated with the porous current collector to form a catalyst layer including the conductive material by electroplating the conductive material on the porous current collector to prepare a porous current collector/catalyst layer; may include.

The porous current collector may include nickel.

The conductive material is silver, platinum, tin, copper, gold, platinum, palladium, nickel, indium, aluminum, iron, rhodium, ruthenium, osmium, cobalt, molybdenum, zinc, vanadium, tungsten, titanium, manganese, chromium, and these It may include one or more selected from the group consisting of alloys.

The conductive material may include silver.

The thickness of the porous current collector may be 1 to 500 μm.

The thickness of the catalyst layer may be 1 to 50 μm.

The electrode laminate of the present invention, a membrane electrode assembly including the same, and a manufacturing method thereof are manufactured by directly coating a conductive material on a porous electrode substrate by electroplating without the need to separately cast an electrode to prepare a membrane electrode assembly (MEA). You can save time on

In addition, the electrode stack, the membrane electrode assembly and a method of manufacturing the same comprising them of the invention it is possible to improve the carbon dioxide (CO ₂₎ and the reactivity for efficient contact of the conductive material and the carbon dioxide (CO ₂₎ of the catalyst bed .

1 is a schematic view of an electrode laminate according to the present invention.
2 is an XRD pattern graph of Ag-plated electrode laminates, nickel mesh, and silver (Ag) prepared according to Examples 1 to 4;
3A is a photograph and SEM analysis image of the electrode laminate prepared according to Example 1. FIG.
3B is a photograph and SEM analysis image of the electrode laminate prepared according to Example 2.
3C is a photograph and SEM analysis image of the electrode laminate prepared according to Example 3.
3D is a photograph and SEM analysis image of the electrode laminate prepared according to Example 4.
4 is a linear sweep voltammetry (LSV) analysis result of a half cell manufactured according to Device Examples 1 to 4;
5 is a graph of current change in a voltage range from -1.4 to 2.0V of a half cell manufactured according to Device Example 2. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily carry out the present invention.

However, the following description is not intended to limit the present invention to specific embodiments, and when it is determined that a detailed description of a related known technology may obscure the gist of the present invention in describing the present invention, the detailed description thereof will be omitted. .

The terminology used herein is only used to describe specific embodiments, and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, element, or combination thereof described in the specification exists, but is one or more other features or It should be understood that the existence or addition of numbers, steps, acts, elements, or combinations thereof is not precluded in advance.

1 is a schematic view of an electrode laminate according to the present invention.

Hereinafter, the electrode laminate of the present invention and a membrane electrode assembly including the same will be described in detail with reference to FIG. 1 .

The present invention is a porous current collector; and a catalyst layer formed on the porous current collector and including a conductive material, wherein the porous current collector is in the form of a mesh.

The porous current collector may include nickel.

The catalyst layer may be formed on one surface of the porous current collector.

The thickness of the porous current collector may be 1 to 500 μm. When the thickness of the porous current collector exceeds 500 μm, it is not preferable because it is too thick to produce an MEA.

The conductive material is silver, platinum, tin, copper, gold, platinum, palladium, nickel, indium, aluminum, iron, rhodium, ruthenium, osmium, cobalt, molybdenum, zinc, vanadium, tungsten, titanium, manganese, chromium, and these It may include one or more selected from the group consisting of alloys of, preferably silver. The silver (Ag) is inexpensive and has high CO Faradaic Effiency, so it is preferable to be used as a conductive material for the catalyst layer.

The thickness of the catalyst layer may be 1 to 50 μm.

If the catalyst layer thickness is less than 1 μm, it is undesirable because the Ni surface is partially exposed due to the formation of a non-uniform plating layer on the porous current collector (Ni mesh), and thus the catalyst role cannot be properly performed. It is undesirable because it may break the joint of the mesh, and clogging may occur due to the overcharge phenomenon at the edge portion in the mesh.

The electrode laminate may be for use as a carbon dioxide reduction electrode.

The present invention provides a positive electrode comprising the electrode laminate; cathode; and an electrolyte membrane between the positive electrode and the negative electrode.

The electrolyte membrane may include Nafion.

The present invention provides any one electronic component selected from the group consisting of a water decomposition device including the membrane electrode assembly, a fuel cell, a photoelectric conversion device, and a carbon dioxide reduction device.

Hereinafter, a method for manufacturing the membrane electrode assembly of the present invention will be described in detail.

First, a porous current collector is prepared (step a).

The porous current collector may be in the form of a mesh.

The porous current collector may include nickel.

Next, a catalyst layer including a conductive material is formed by electroplating a conductive material on the porous current collector to prepare an electrode laminate including a porous current collector/catalyst layer (step b).

Step (b) is (b-1) impregnating the porous current collector in a plating solution; and (b-2) applying an electric current to the plating solution impregnated with the porous current collector and electroplating the conductive material on the porous current collector to form a catalyst layer including the conductive material to prepare a porous current collector/catalyst layer; may include.

The plating solution may include the conductive material.

The conductive material is silver, platinum, tin, copper, gold, platinum, palladium, nickel, indium, aluminum, iron, rhodium, ruthenium, osmium, cobalt, molybdenum, zinc, vanadium, tungsten, titanium, manganese, chromium, and these It may include one or more selected from the group consisting of alloys of, preferably silver.

The thickness of the porous current collector may be 1 to 500 μm.

The thickness of the catalyst layer may be 1 to 50 μm.

[Example]

Hereinafter, a preferred embodiment of the present invention will be described. However, this is for illustrative purposes only, and the scope of the present invention is not limited thereto.

Example 1: Electrode laminate 1 (Ag-Mesh 1)

A 0.2mm porous current collector Ni Mesh was impregnated with a silver plating solution (silver cyanide 5g/L, potassium cyanide 20g/L, potassium carbonate 15g/L), and ^{a current density of 15mA/cm 2} was applied at room temperature for 10 minutes to make the silver 15μm. (content 0.0139 g) A plated electrode laminate was prepared.

Example 2: Electrode laminate 2 (Ag-Mesh 2)

An electrode laminate plated with silver 30 μm (content 0.0095 g) was prepared in the same manner as in Example 1, except that the current density was applied for 20 minutes instead of for 10 minutes.

Example 3: Electrode laminate 3 (Ag-Mesh 3)

An electrode laminate plated with silver 45 μm (content 0.0158 g) was prepared in the same manner as in Example 1, except that the current density was applied for 30 minutes instead of for 10 minutes.

Example 4: Electrode Laminate 4 (Ag-Mesh 4)

An electrode laminate plated with silver 60 μm (content 0.0436 g) was prepared in the same manner as in Example 1 except that the current density was applied for 40 minutes instead of applying for 10 minutes.

Device Example 1: Half Cell Manufacturing 1

A Pt mesh was used as a counter electrode, and an Ag/AgCl electrode was used as a reference electrode. The working electrode had an electrode size of 2 x 1.5 cm and ^{an area of 3 cm 2} , and the electrode stack prepared according to Example 1 was used. A half cell was prepared by using 0.5M KHCO _{3 electrolyte as an electrolyte.}

Device Example 2: Half Cell Manufacturing 2

Half Cell in the same manner as in Device Example 1, except that the electrode stack manufactured according to Example 2 was used instead of using the electrode stack manufactured according to Example 1 as the working electrode in Device Example 1 was prepared.

Device Example 3: Half Cell Manufacturing 3

Half Cell in the same manner as in Device Example 1 except for using the electrode stack manufactured according to Example 3 instead of using the electrode stack manufactured according to Example 1 as the working electrode in Device Example 1 was prepared.

Device Example 4: Half Cell Manufacturing 4

Half Cell in the same manner as in Device Example 1 except for using the electrode stack manufactured according to Example 4 instead of using the electrode stack manufactured according to Example 1 as the working electrode in Device Example 1 was prepared.

[Test Example]

Test Example 1: XRD and SEM analysis

2 is an XRD pattern graph of the Ag-plated electrode laminate, nickel mesh, and silver (Ag) prepared according to Examples 1 to 4, and FIGS. 3A to 3D are electrode laminates prepared according to Examples 1 to 4; are photographs and SEM analysis images.

Referring to FIGS. 2 and 3A to 3D , it can be seen that the intensity of the XRD pattern increases as the plating time increases, and it can be seen that grain growth occurs according to the plating time. In addition, it can be confirmed that grain growth is made through the SEM image.

Test Example 2: Evaluation of electrochemical properties

4 is a linear sweep voltammetry (LSV) analysis result of a half cell manufactured according to Device Examples 1 to 4; The test was carried out in a voltage range of 0 to -2.0V, and the experiment was carried out while applying a voltage of 30mV. In addition, Table 1 shows the E(RHE) and overvoltage measurement results of Device Examples 1 to 4. The overvoltage was measured by the E(RHE) conversion equation, and the conversion equation is as shown in Equation 1 below.

[Equation 1]

E(RHE) = E(Ag/AgCl) + 0.197V + 0.05915V x pH

Current
density
(mA/cm ² ) Device Example 1 Device Example 2 Device Example 3 Device Example 4 Potential (V)
(E(Ag/AgCl)) E (RHE)
(V) Over
potential
(mV) Potential (V)
(E(Ag/AgCl)) E (RHE)
(V) Over
potential
(mV) Potential (V)
(E(Ag/AgCl)) E (RHE)
(V) Over
potential
(mV) Potential (V)
(E(Ag/AgCl)) E (RHE)
(V) Over
potential
(mV) 5 -1.39 -0.779 249 -1.38 -0.769 239 -1.42 -0.809 279 -1.48 -1.869 339 10 -1.59 -0.979 449 -1.52 -0.909 379 -1.59 -0.979 449 -1.69 -1.079 579 15 -1.75 -1.139 609 -1.63 -1.019 489 -1.71 -1.099 569 -1.83 -1.219 589 20 -1.87 -1.259 729 -1.72 -1.109 579 -1.82 -1.209 679 -1.9 -1.289 759

Referring to Figure 4 and Table 1, since the reference electrode used in the half cell is Ag/AgCl, the voltage was converted and calculated based on the RHE electrode according to the above conversion formula, and the pH was changed to 7 because an electrolyte of _{0.5M KHCO 3 was used.} Calculated. It can be seen that in all of the half cells according to Device Examples 1 to 4, the overvoltage increases as the current density increases, and the overvoltage tends to increase as the loading amount of the Ag catalyst in the nickel mesh increases. In the case of Device Example 2, The lowest overvoltage can be seen at a current of 5mA/cm ^{2 .}

Test Example 3: Life evaluation graph

5 is a graph of current change in a voltage range from -1.4 to 2.0V at 0.2V intervals of a half cell manufactured according to Device Example 2. FIG.

Referring to FIG. 5 , it can be confirmed that the value of the generated current increases as the voltage increases. In the case of Device Example 2, it can be seen that the amount of current generated at each voltage is in the range of 30 to 50 mA, which means that the product generated after the reaction does not fall from the catalyst surface, thereby reducing the reaction area and reducing the resistance at the surface. because it increases For this reason, it can be seen that the low overvoltage is shown.

Although preferred embodiments of the present invention have been described above, those of ordinary skill in the art can add, change, delete or It will be possible to variously modify and change the present invention by addition, etc., which will also be included within the scope of the present invention. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as being distributed may also be implemented in a combined form. The scope of the present invention is indicated by the claims to be described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

Claims (18)

porous current collector; and
A catalyst layer formed on the porous current collector and comprising a conductive material;
The porous current collector will be in the form of a mesh, the electrode laminate. The method of claim 1,
The porous current collector is an electrode laminate, characterized in that it comprises nickel. The method of claim 1,
The electrode laminate, characterized in that the catalyst layer is formed on one surface of the porous current collector. The method of claim 1,
The porous current collector has a thickness of 1 to 500 μm. The method of claim 1,
The conductive material is silver, platinum, tin, copper, gold, platinum, palladium, nickel, indium, aluminum, iron, rhodium, ruthenium, osmium, cobalt, molybdenum, zinc, vanadium, tungsten, titanium, manganese, chromium, and these An electrode laminate comprising at least one selected from the group consisting of an alloy of The method of claim 5,
The electrode laminate, characterized in that the conductive material comprises silver. The method of claim 1,
The electrode laminate, characterized in that the thickness of the catalyst layer is 1 to 50㎛. The method of claim 1,
The electrode laminate, characterized in that for use as a carbon dioxide reduction electrode. A positive electrode comprising the electrode stack according to claim 1;
cathode; and
an electrolyte membrane between the positive electrode and the negative electrode;
A membrane electrode assembly comprising. The method of claim 9,
The electrolyte membrane is a membrane electrode assembly, characterized in that it comprises Nafion. Any one electronic component selected from the group consisting of a water decomposition device comprising the membrane electrode assembly according to claim 9, a fuel cell, a photoelectric conversion device, and a carbon dioxide reduction device. (a) preparing a porous current collector; and
(b) forming a catalyst layer including a conductive material by electroplating a conductive material on the porous current collector to prepare an electrode laminate including a porous current collector/catalyst layer;
The method for producing an electrode laminate, wherein the porous current collector is in the form of a mesh. The method of claim 12,
The step (b) is
(b-1) impregnating the porous current collector in a plating solution; and
(b-2) applying a current to the plating solution impregnated with the porous current collector to form a catalyst layer including a conductive material by electroplating the conductive material on the porous current collector to prepare a porous current collector/catalyst layer; A method of manufacturing an electrode laminate, comprising: The method of claim 12,
The porous current collector is a method of manufacturing an electrode stack, characterized in that it comprises nickel. The method of claim 12,
The conductive material is silver, platinum, tin, copper, gold, platinum, palladium, nickel, indium, aluminum, iron, rhodium, ruthenium, osmium, cobalt, molybdenum, zinc, vanadium, tungsten, titanium, manganese, chromium, and these A method of manufacturing an electrode stack, comprising at least one selected from the group consisting of an alloy of The method of claim 15,
The method of manufacturing an electrode laminate, characterized in that the conductive material includes silver. The method of claim 12,
The thickness of the porous current collector is a method of manufacturing an electrode stack, characterized in that 1 to 500㎛. The method of claim 12,
A method of manufacturing an electrode laminate, characterized in that the catalyst layer has a thickness of 1 to 50 μm.

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