Preparation method of anion exchange membrane water electrolysis system

Abstract

The invention provides a preparation method of an anion exchange membrane water electrolysis system. The preparation method comprises the following steps: respectively manufacturing an initial reduction electrode and an oxidation electrode; inserting an anion exchange membrane between the initial reduction electrode and the oxidation electrode to manufacture an initial membrane-electrode assembly; and supplying an alkaline aqueous solution into the initial membrane-electrode assembly and activating an initial reduction electrode, in which the initial reduction electrode includes NiMo-based alloy particles in which a molar ratio of Ni and Mo is 1: 1 to 6: 1, and an oxidation number of Mo is 4 +, 5 + or 6 +, and an oxidation number of Ni is 4 +, 5 + or 6 +. Wherein the activation is carried out by applying a current at a current density of 25 mA / cm < 2 > to 200 mA / cm < 2 > and holding the current at 50 DEG C to 60 DEG C for 90 minutes to 360 minutes. The anion exchange membrane water electrolysis system prepared by the preparation method shows improved durability and efficiency and excellent water electrolysis performance.

Description

Cross-reference to related applications

[0001] This application is based on and claims priority to Korean Patent Application No. 10-2023-0061678, filed on May 12, 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] This invention relates to a method for preparing an anion exchange membrane water electrolysis system, which exhibits improved durability and efficiency as well as excellent water electrolysis performance. Background Technology

[0003] The importance of technologies that can produce hydrogen in an environmentally friendly way is being emphasized, as hydrogen is a next-generation energy source that can solve fossil fuel shortages and environmental pollution.

[0004] Therefore, research on water electrolysis technology using electrolysis is actively underway. Representative water electrolysis technologies include proton exchange membrane electrolysis (PEMWE), anion exchange membrane electrolysis (AEMWE), and alkaline water electrolysis (AWE).

[0005] In alkaline water electrolysis, nickel-based oxides and cobalt-based oxides are generally used as reduction and oxidation electrocatalysts, and alkaline aqueous solutions such as KOH are used as the electrolyte. Alkaline electrolysis has the advantages of not requiring precious metal catalysts and being able to operate at relatively low temperatures. However, it also has disadvantages such as low hydrogen production rates and large hydrogen production system design requirements. In addition, liquid alkaline electrolytes are prone to leakage, and leakage increases resistance, thereby reducing current density and ultimately leading to a decrease in water electrolysis efficiency.

[0006] On the other hand, proton exchange membrane (PEM) water electrolysis is a water electrolysis system that uses solid electrolyte membranes, such as those from Nafion, instead of liquid electrolytes. Since solid electrolyte membranes occupy a smaller volume than liquid electrolytes, the system size can be reduced, and high current densities can be provided. However, because this system operates in an acidic environment, it requires the use of acid-resistant, highly corrosive platinum-based catalysts, such as IrO2 and Pt, as reduction and oxidation electrocatalysts. The use of expensive platinum-based catalysts increases the cost of hydrogen production, which is the biggest limitation to the commercialization of PEM water electrolysis.

[0007] In contrast, anion exchange membrane water electrolysis is a system that leverages the advantages of existing systems while overcoming their disadvantages. Because it operates in an alkaline environment, it is possible to use non-platinum-based metals as catalyst materials, and significant energy densities can be achieved with a compact system. However, non-platinum-based metal catalysts exhibit lower catalytic activity than platinum-based metal catalysts, thus suffering from lower water electrolysis efficiency.

[0008] Therefore, research and development are underway to develop catalysts with excellent catalytic activity to improve water electrolysis efficiency and anion exchange membrane water electrolysis systems. Regarding catalysts, research is progressing towards applying previously developed half-cell catalysts for alkaline environments to anion exchange membrane systems. However, the applied catalysts still suffer from low catalytic activity and deteriorating durability. Summary of the Invention

[0009] [Technical Issues] To address the aforementioned problems in the prior art, a method for preparing an anion exchange membrane water electrolysis system is provided, which exhibits improved durability and efficiency as well as excellent water electrolysis performance.

[0010] An anion exchange membrane water electrolysis system prepared by the above preparation method is also provided.

[0011] An activation method that can improve the performance of anion exchange membrane water electrolysis systems is also provided.

[0012] [Technical Solution] A method for preparing an anion exchange membrane water electrolysis system according to an embodiment of the present invention includes the following steps: The initial reduction electrode and oxidation electrode were manufactured separately; An initial membrane-electrode assembly is fabricated by inserting an anion exchange membrane between the initial reduction electrode and the initial oxidation electrode; and The initial reduction electrode is activated by supplying an alkaline aqueous solution to the initial membrane-electrode assembly. The initial reduction electrode comprises NiMo-based alloy particles, wherein the molar ratio of Ni to Mo in the NiMo-based alloy particles is 1:1 to 6:1, and the oxidation number of Mo is 4+, 5+, or 6+. Activation is achieved by applying 25 mA / cm 2 Up to 200mA / cm 2 The current density is applied and the current is maintained at 50°C to 60°C for 90 minutes to 360 minutes.

[0013] In addition, another embodiment of the present invention provides an anion exchange membrane water electrolysis system prepared by the above-described method for preparing anion exchange membrane water electrolysis systems, comprising: a reduction electrode including a particulate NiMo-based alloy catalyst; an oxidation electrode; an anion exchange membrane between the reduction electrode and the oxidation electrode; and an alkaline aqueous solution, wherein the NiMo-based alloy catalyst comprises Ni and Mo in a molar ratio of 6:1 to 101:1, and the oxidation number of Mo is 5+ or 6+.

[0014] A method for activating an anion exchange membrane water electrolysis system according to another embodiment of the present invention includes the following steps: activating an initial reduction electrode by supplying an alkaline aqueous solution to an initial anion exchange membrane water electrolysis system, the initial anion exchange membrane water electrolysis system comprising an initial reduction electrode, an oxidation electrode, and an anion exchange membrane between the initial reduction electrode and the oxidation electrode, wherein the initial reduction electrode comprises NiMo-based alloy particles, wherein the molar ratio of Ni to Mo in the NiMo-based alloy particles is 1:1 to 6:1 and the oxidation number of Mo is 4+, 5+, or 6+, the activation being performed by supplying an alkaline aqueous solution to an initial anion exchange membrane water electrolysis system at 25 mA / cm². 2 Up to 200mA / cm 2 The current density is applied and the current is maintained at 50°C to 60°C for 90 minutes to 360 minutes.

[0015] [Beneficial Effects] The preparation method of this invention can produce anion exchange membrane water electrolysis systems with improved durability and efficiency and excellent water electrolysis performance. Attached Figure Description

[0016] Figure 1A This shows the presence of H2O, MoO2, and H2O / MoO2 clusters in Ni. 24 A diagram of adsorption energies on the surface of Mo4 alloy. Figure 1B This is a graph showing the adsorption energies corresponding to the adsorption sites of the hydrogen intermediate H*.

[0017] Figure 2 This is a schematic diagram illustrating the hydrogen evolution reaction mechanism of NiMo-based alloys in an alkaline environment.

[0018] Figure 3 This is a schematic diagram illustrating an anion exchange membrane water electrolysis system including a dual-supply type alkaline aqueous solution circulation device according to an embodiment of the present invention.

[0019] Figure 4 This is a schematic diagram illustrating an anion exchange membrane water electrolysis system including a shared-supply type alkaline aqueous solution circulation device according to another embodiment of the present invention.

[0020] Figure 5 This is a schematic diagram illustrating an anion exchange membrane water electrolysis system including an anode-supply type alkaline aqueous solution circulation device according to another embodiment of the present invention.

[0021] Figures 6A to 6D The figures shown are BET analysis results of the NiMo-based alloy particles prepared in Examples 1, 2, 3, and 4.

[0022] Figure 7This is a graph showing the results of linear sweep voltammetry (LSV) used to evaluate the hydrogen evolution reaction activity as a function of the molar ratio of Ni to Mo in NiMo-based alloys.

[0023] Figure 8 This is a graph showing the results of X-ray photoelectron spectroscopy (XPS) analysis of the initial oxidation number of Mo in the NiMo-based alloys prepared in Examples 1 to 4.

[0024] Figure 9 This is a graph showing the XPS results of the analysis of the change in the oxidation number of Mo in the Ni3Mo alloy before and after activation.

[0025] Figure 10 This is a graph showing the results of the change in current as a function of voltage control observed in an anion exchange membrane water electrolysis system activated by increasing or decreasing the applied voltage.

[0026] Figure 11 This is a graph showing the results of the change in current as a function of voltage control observed in an anion exchange membrane water electrolysis system activated by applying a current at a predetermined current density and maintaining that current for a predetermined time.

[0027] Figure 12 This shows the values ​​at 25 mA / cm. 2 50mA / cm 2 100mA / cm 2 and 200mA / cm 2 The figure shows the polarization evaluation results of the activated anion exchange membrane water electrolysis system under the current density conditions.

[0028] Figure 13 This shows the values ​​at 25 mA / cm. 2 50mA / cm 2 100mA / cm 2 and 200mA / cm 2 The figure shows the durability evaluation results of the activated anion exchange membrane water electrolysis system under the current density conditions.

[0029] Figure 14 It is a graph showing the state of Mo as a function of pH, published in the reference "Anatolyevich, Pavel. "The Revised Pourbaix Diagram for Molybdenum." HMo 2.10: 3".

[0030] Figure 15 This shows the results at 25 mA / cm. 2 50mA / cm 2 100mA / cm 2 200mA / cm2 The figure shows the X-ray fluorescence (XRF) spectra of the Mo residue in an anion exchange membrane water electrolysis system activated under certain current density conditions.

[0031] Figure 16 This is a graph showing the evaluation results of the effect of activation time on the performance development of NiMo-based alloys.

[0032] Figure 17 This is a graph showing the results of evaluating the polarization of anion exchange membrane water electrolysis system based on the alkaline aqueous solution circulation method.

[0033] Figure 18 This is a graph showing the evaluation results of the durability of the anion exchange membrane water electrolysis system. Detailed Implementation

[0034] As used in this article, the terms “first,” “second,” etc., are used to describe various components, and these terms are only used to distinguish one component from others.

[0035] Furthermore, the terminology used in this specification is for illustrative purposes only and is not intended to limit the invention. Singular expressions may include plural expressions unless expressed differently in the context. In this specification, the terms "comprising," "equipment," or "having" are used only to describe the implemented features, quantities, steps, components, or combinations thereof, and do not preclude the possibility of having or adding one or more different features, quantities, steps, components, or combinations thereof.

[0036] Furthermore, in this invention, when referring to a layer or element being formed "on" or "above" a layer or element, it means that each layer or element is formed directly on these layers or elements, or that other layers or elements may be additionally formed between layers, objects, or substrates.

[0037] In addition, in this invention, "reduction electrode", "membrane-electrode assembly", and "anion exchange membrane electrolysis water system" refer to the activated reduction electrode, membrane-electrode assembly, and anion exchange membrane electrolysis water system, respectively, while "initial reduction electrode", "initial membrane-electrode assembly", and "initial anion exchange membrane electrolysis water system" refer to the unactivated reduction electrode, membrane-electrode assembly, and anion exchange membrane electrolysis water system, respectively.

[0038] In addition, "NiMo-based alloy particles" refers to alloy particles before activation used to manufacture the initial reduction electrode, while "NiMo-based alloy catalyst" or "granular NiMo-based alloy catalyst" refers to alloy particles after activation.

[0039] This invention can be modified and has many forms, and specific embodiments will be described in detail below. However, it should be understood that these descriptions are not intended to limit the invention to the specific forms disclosed, but rather are intended to cover all modifications, equivalents, and alternatives that fall within the spirit and scope of this invention.

[0040] The following describes in detail the preparation method of the anion exchange membrane water electrolysis system according to embodiments of the present invention, the anion exchange membrane water electrolysis system prepared according to the method, and the activation method that can improve the performance of the anion exchange membrane water electrolysis system.

[0041] A method for preparing an anion exchange membrane water electrolysis system according to one embodiment of the present invention includes: The steps for manufacturing the initial reduction electrode and oxidation electrode separately (Step 1); The step of fabricating the initial membrane-electrode assembly by inserting an anion exchange membrane between the initial reduction electrode and the oxidation electrode (step 2); and Step 3 involves activating the initial reduction electrode by supplying an alkaline aqueous solution to the initial membrane-electrode assembly. The initial reduction electrode comprises NiMo-based alloy particles, wherein the NiMo-based alloy particles comprise Ni and Mo in a molar ratio of 1:1 to 6:1, and the oxidation number of Mo is 4+, 5+, or 6+. The activation is performed at 25 mA / cm 2 Up to 200mA / cm 2 The current density is applied and the current is maintained at 50°C to 60°C for 90 minutes to 360 minutes.

[0042] As a result of activating the initial reduction electrode, a reduction electrode is manufactured. The reduction electrode comprises a particulate NiMo-based alloy catalyst derived from NiMo-based alloy particles, wherein the NiMo-based alloy catalyst comprises Ni and Mo in a molar ratio of 6:1 to 101:1, and the oxidation number of Mo is 5+ or 6+.

[0043] The inventors of this application discovered a problem: when using NiMo-based alloy catalysts developed as non-platinum catalysts for anion exchange membrane water electrolysis, Mo is lost in an alkaline environment during the operation of the anion exchange membrane water electrolysis system, resulting in deterioration of water electrolysis performance. By investigating the performance development mechanism of NiMo-based alloys, it was found that when the molar ratio and oxidation number of the NiMo alloy, the activation method of the water electrolysis system, and consequently the electrolyte supply method are controlled and optimized, even with a non-platinum catalyst, the prepared anion exchange membrane water electrolysis system can exhibit excellent water electrolysis performance at the level of a platinum catalyst. Furthermore, the anion exchange membrane water electrolysis system has improved durability and efficiency, exhibiting only minor performance degradation even after long-term operation, thus completing this invention.

[0044] Specifically, NiMo-based alloy particles containing Ni and Mo in different molar ratios were prepared. An initial reduction electrode and an initial anion exchange membrane water electrolysis system incorporating these particles were then fabricated and activated, and the battery performance was tested. The results showed that when the water electrolysis system was running in an alkaline environment, Mo in the NiMo-based alloy was significantly lost, resulting in changes in the molar ratio of Ni to Mo and the oxidation number of Mo in the alloy.

[0045] Subsequently, thermodynamic calculations were used to determine the mechanistic cause of Mo loss. Specifically, the rate of Mo loss from Ni was calculated. 24 The energy lost in the Mo8 alloy is sequential, and these processes all proceed in a stable direction (see Table 3 in Experimental Example 3 below). Furthermore, computational chemistry confirmed the stability of the NiMo-based alloy, as all Mo present on the surface is lost in the alkaline environment.

[0046] Figure 1A This shows the presence of H2O, MoO2, and H2O / MoO2 clusters in Ni. 24 A diagram of adsorption energies on the surface of Mo4 alloy. Figure 1B This is a graph showing the adsorption energies corresponding to the adsorption sites of the hydrogen intermediate H*.

[0047] Figure 1A Calculations of the adsorption energy confirmed that the Mo lost during the activation of the water electrolysis system was adsorbed by water and existed in the form of H2O / MoO2 clusters, and according to... Figure 1B The calculated adsorption energies at the adsorption sites confirmed that the intermediate hydrogen is more stable when adsorbed onto Ni sites rather than Mo sites. Based on these results, the following mechanism can be predicted: H2O / MoO2 clusters adsorb onto the Ni surface, and after water electrolysis, hydrogen migrates to the Ni surface to generate hydrogen.

[0048] Figure 2This is a schematic diagram illustrating the hydrogen evolution reaction mechanism of NiMo-based alloys, specifically Ni3Mo alloys, in an alkaline environment. Figure 2 These are merely examples to illustrate the invention, and the invention is not limited thereto.

[0049] refer to Figure 2 The hydrogen evolution reaction of NiMo-based alloys in an alkaline environment includes: (1) loss of all Mo on the surface of NiMo-based alloys, (2) formation of Mo oxides from the lost Mo, (3) re-adsorption onto the bare Ni surface in the form of H2O / Mo oxides, (4) dissociation reaction of water and adsorption of hydrogen intermediate H* at Ni sites (dual active sites), and (5) hydrogen evolution mechanism via Heyrovsky or Tafel reaction.

[0050] Therefore, the structure of the stable and highly active NiMo-based alloy catalyst in an alkaline environment is as follows: the catalyst surface is composed of Ni, Mo dissolves into MoO2, and MoO2 reacts with H2O to form H2O / Mo oxide clusters, which are then adsorbed onto the Ni surface. Furthermore, the molar ratio of Ni to Mo in the alloy catalyst is between 6:1 and 101:1, and the oxidation number of Mo is 5+ or 6+.

[0051] When the above molar ratio requirements are met, only surface Mo on the NiMo-based alloy is selectively dissolved, and the resulting Mo oxide can form clusters with water and be fully adsorbed onto the Ni surface. When only Mo exists on the surface of the alloy catalyst as is conventional, it is difficult to control the molar ratio of Ni and Mo and the oxidation number of Mo to meet the above requirements.

[0052] Based on the aforementioned performance development mechanism of NiMo-based alloys, this invention controls and optimizes the molar ratio of Ni and Mo in NiMo-based alloys, the oxidation number of Mo, the activation method of the water electrolysis system, and the electrolyte supply method, thereby realizing a stable and highly active NiMo-based alloy catalyst structure.

[0053] Therefore, the reduction electrode in the anion exchange membrane water electrolysis system prepared by the preparation method of the anion exchange membrane water electrolysis system according to the present invention comprises a NiMo-based alloy catalyst with a stable and highly active structure.

[0054] Specifically, the anion exchange membrane water electrolysis system prepared by the preparation method of the anion exchange membrane water electrolysis system according to the present invention includes: a reduction electrode comprising a particulate NiMo-based alloy catalyst; an oxidation electrode; an anion exchange membrane disposed between the reduction electrode and the oxidation electrode; and an alkaline aqueous solution, wherein the NiMo-based alloy catalyst comprises Ni and Mo in a molar ratio of 6:1 to 101:1, and the oxidation number of Mo is 5+ or 6+.

[0055] In this invention, the molar ratio of Ni to Mo in the NiMo-based alloy catalyst can be determined by XRF analysis. Detailed analytical methods and conditions are described in the experimental examples below.

[0056] Furthermore, the oxidation number of Mo in NiMo-based alloy catalysts can be determined by XPS analysis. Detailed analytical methods and conditions are described in the experimental examples below.

[0057] In addition, NiMo-based alloy catalysts include a Ni layer on the surface.

[0058] The Ni layer is formed due to the loss of Mo from the surface of NiMo-based alloy particles during the activation process.

[0059] Meanwhile, XRF analysis of the alloy can be used to determine the loss rate of each element in the NiMo-based alloy before and after activation. Detailed analytical methods and conditions are described in the experimental examples below.

[0060] Furthermore, the NiMo-based alloy catalyst is prepared from NiMo-based alloy particles, which can be prepared by a powder method using a co-precipitation reaction. Therefore, compared with NiMo-based alloys prepared by conventional methods such as electroplating or deposition, the NiMo-based alloy catalyst has particulate form (powder) and has a relatively small average particle size and a large specific surface area.

[0061] In addition, NiMo-based alloy catalysts are porous particles with multiple pores within them.

[0062] Furthermore, when electrodes are conventionally manufactured using alloy catalysts with nanoscale average particle sizes, the catalyst layer is formed by electroplating or deposition onto the electrode substrate, resulting in an electrode with a relatively small specific surface area. In contrast, in this invention, a slurry for forming the initial reduction electrode is prepared by dispersing particulate alloys in a solvent, then coating it onto a release film, drying, and separating it to prepare a catalyst layer, which is directly used as the reduction electrode. Therefore, the resulting reduction electrode has a larger specific surface area than conventionally manufactured reduction electrodes, and thus exhibits superior catalytic activity.

[0063] In addition, NiMo-based alloy catalysts can achieve a concentration of 1.0 mg / cm³. 2 The above high loading is included in the reduction electrode.

[0064] Meanwhile, the anion exchange membrane water electrolysis system according to the present invention includes a membrane-electrode assembly (MEA) as a unit cell, which is composed of a reduction electrode (cathode, negative electrode) including the above-mentioned particulate NiMo-based alloy catalyst, an oxidation electrode (anode, positive electrode) and an anion exchange membrane between the reduction electrode and the oxidation electrode.

[0065] An anion exchange membrane water electrolysis system may include multiple membrane-electrode assemblies, the number of which can be appropriately determined based on the performance requirements of the water electrolysis system.

[0066] Multiple membrane-electrode components are connected and stacked together to form a stack.

[0067] Therefore, the anion exchange membrane water electrolysis system includes multiple membrane-electrode assemblies, a battery stack for electrolyzing an alkaline aqueous solution to generate hydrogen and oxygen, and optionally, an alkaline aqueous solution circulation device that supplies the alkaline aqueous solution to the battery stack, a generated gas discharge device for discharging the generated oxygen and hydrogen in the battery stack, and a power supply device for applying voltage and current to and controlling the battery stack.

[0068] In the membrane-electrode assembly, the reduction catalyst at the reduction electrode initiates the hydrogen evolution reaction (HER), resulting in the formation of hydrogen (H2) and hydroxide ions (OH-). - At this point, the aforementioned particulate NiMo-based alloy catalyst is used as a reduction catalyst.

[0069] Typically, electrodes in a water electrolysis system consist of a catalyst layer containing a catalyst and an electrode substrate for supporting the catalyst layer. However, the reduction electrode in this invention does not include an electrode substrate, but consists only of a catalyst layer comprising a NiMo-based alloy catalyst.

[0070] Meanwhile, at the oxidation electrode, the oxygen evolution reaction (OER) is induced by the oxidation catalyst, and the hydroxide ions generated at the reduction electrode and diffused through the anion exchange membrane are oxidized to produce water and oxygen.

[0071] The oxidation catalyst can be one or more selected from the group consisting of Ni, NiCoFe, Ir and NiFe layered double hydroxides (LDH).

[0072] In addition to the catalyst layer comprising the oxidation catalyst, the oxidation electrode may further include an electrode substrate for supporting the catalyst layer. The electrode substrate is a conductive porous material.

[0073] Oxidation electrodes can be manufactured according to conventional methods. For example, oxidation electrodes can be manufactured by a manufacturing method that includes the following steps: applying a slurry for forming the oxidation electrode onto a release film, the slurry including an oxidation catalyst, a binder, and a solvent; drying the slurry; and then separating the slurry from the release film; or by a manufacturing method that includes the steps of coating, plating, or depositing an oxidation catalyst on an electrode substrate.

[0074] In addition, the function of anion exchange membranes is to remove OH- -Ions move from the reduction electrode to the oxidation electrode. As an anion exchange membrane, any anion exchange membrane commonly used in anion exchange membrane water electrolysis systems, such as trimethylammonium-functionalized polystyrene, can be used without particular restrictions. Commercially available ones can be used; for example, the Sustainion™ X37-50 grade RT anion exchange membrane manufactured by Sustainion can be used.

[0075] Furthermore, in addition to the oxidation electrode, reduction electrode, and anion exchange membrane, the membrane-electrode assembly may optionally include gaskets for sealing and clamping the edges of the membrane-electrode assembly.

[0076] Multiple membrane-electrode components with the above structure are connected in series and stacked to form a stack.

[0077] In addition, in anion exchange membrane water electrolysis systems, besides the membrane-electrode assembly, the stack may also include one or more of a porous transport layer and a separator or bipolar plate.

[0078] A porous transport layer is located on the electrode side, not in contact with the anion exchange membrane in the membrane-electrode assembly, and serves to conduct electricity, transport alkaline aqueous solutions to the electrode, and expel generated gases to the outside. The porous transport layer can be located on the reduction electrode, the oxidation electrode, or both. Nickel foam can be used as a porous transport layer for the reduction electrode, located on one side of the reduction electrode. Alternatively, carbon paper can be used as a porous transport layer for the oxidation electrode, located on one side of the oxidation electrode.

[0079] In addition, the separators are located on both sides of the membrane-electrode assembly to support and connect two adjacent membrane-electrode assemblies in series.

[0080] Furthermore, since the partition is a metal plate such as Ni, it can conduct electricity applied by the power source. Additionally, flow paths are formed within the partition to allow the alkaline aqueous solution supplied from the alkaline aqueous solution circulation device to move towards the porous transport layer. Moreover, the partition can be used to discharge the generated gas to the outside and transfer the heat generated by the reaction.

[0081] In addition, the anion exchange membrane water electrolysis system according to the present invention may further include an alkaline aqueous solution circulation device for supplying alkaline aqueous solution to the stack and discharging alkaline aqueous solution.

[0082] The alkaline aqueous solution may include one or more alkali metal hydroxides, such as potassium hydroxide and sodium hydroxide. More specifically, it may include alkali metal hydroxides with a concentration of 0.1M to 1M. More specifically, the alkaline aqueous solution may be an aqueous solution of potassium hydroxide with a concentration of 0.1M to 1M.

[0083] The alkaline aqueous solution circulation device specifically includes a tank for storing the alkaline aqueous solution, a temperature control device for controlling the temperature by supplying heat to the water electrolysis system, and a flow control device, such as a pump, for maintaining a constant flow rate of the alkaline aqueous solution by controlling the flow rate.

[0084] Alternatively, one or more alkaline aqueous solution circulation devices may be included in the water electrolysis system.

[0085] Based on the method of supplying alkaline aqueous solution, alkaline aqueous solution circulation devices can be classified into shared supply, anodic supply, and dual supply methods. Specifically, the shared supply method supplies alkaline aqueous solution from a single alkaline aqueous solution circulation device to both the oxidation and reduction electrodes. In this case, the anion exchange membrane water electrolysis system includes a single alkaline aqueous solution circulation device. The shared supply type alkaline solution circulation device is connected to both the oxidation and reduction electrodes, supplying alkaline aqueous solution to both. Alternatively, the anodic supply method supplies alkaline aqueous solution to the oxidation electrode. In this case, the water electrolysis system also includes a single alkaline aqueous solution circulation device. The anodic supply type alkaline aqueous solution circulation device is connected to the oxidation electrode, supplying alkaline aqueous solution to it. In contrast, the dual supply method supplies alkaline aqueous solution to both the oxidation and reduction electrodes from alkaline aqueous solution circulation devices separately located at the oxidation and reduction electrodes. The dual supply type alkaline aqueous solution circulation device consists of an alkaline aqueous solution circulation device for the oxidation electrode and an alkaline aqueous solution circulation device for the reduction electrode, each connected to both electrodes.

[0086] Figure 3 This is a schematic diagram illustrating an anion exchange membrane water electrolysis system including a dual-supply alkaline aqueous solution circulation device according to an embodiment of the present invention. Figure 4 This is a schematic diagram illustrating an anion exchange membrane water electrolysis system including a shared-supply type alkaline aqueous solution circulation device according to another embodiment of the present invention. Figure 5 This is a schematic diagram illustrating an anion exchange membrane water electrolysis system including an anode-supply type alkaline aqueous solution circulation device according to another embodiment of the present invention. Figures 3 to 5 These are merely examples to illustrate the invention, and the invention is not limited thereto.

[0087] Meanwhile, the circulation method of alkaline aqueous solution in the anion exchange membrane water electrolysis system affects the amount of Mo loss and the performance of the anion exchange membrane water electrolysis system, especially its durability.

[0088] Specifically, in the shared supply method, Mo dissolution and the dissolution of Mo by negative ionization and migration towards the reduction electrode occur simultaneously when the alkaline aqueous solution comes into direct contact with the NiMo alloy particles. In contrast, in the anodic supply method, the NiMo alloy particles do not come into direct contact with the alkaline aqueous solution. Therefore, the anodic supply method exhibits a lower Mo loss rate than the shared supply method.

[0089] In addition, regarding the performance of the water electrolysis system, unlike the shared supply method that supplies alkaline aqueous solution to both the oxidation and reduction electrodes through a single alkaline aqueous solution circulation device, the dual supply method that supplies alkaline aqueous solution to the oxidation and reduction electrodes through two corresponding alkaline aqueous solution circulation devices can generate hydrogen at a lower voltage.

[0090] In addition to the aforementioned stack and alkaline aqueous solution circulation device, the anion exchange membrane water electrolysis system according to the present invention may also include a gas generation and discharge device and a power supply device.

[0091] In addition, the generated gas discharge device is connected to the outlet of the alkaline aqueous solution circulation device, allowing the gas generated inside the water electrolysis system to be mixed with the alkaline aqueous solution to be discharged, or to be discharged independently. Furthermore, the generated gas discharge device can remove gas at atmospheric pressure (1±0.1), and the gas can be pressurized by controlling the flow rate.

[0092] The generated gas discharge device may include an oxidation electrode generated gas discharge system (or oxidation electrode generated gas discharge unit) for discharging oxygen generated at the oxidation electrode of the anion exchange membrane water electrolysis system and a reduction electrode generated gas discharge system (or reduction electrode generated gas discharge unit) for discharging hydrogen generated at the reduction electrode.

[0093] In addition, the power source supplies the stack of the anion exchange membrane water electrolysis system, specifically the oxidation electrode and the reduction electrode, with the voltage required for electrolysis, which plays a role in controlling the current and voltage in the system, such as consuming and removing residual voltage in the stack.

[0094] Therefore, when an alkaline aqueous solution is supplied to the anion exchange membrane from the alkaline electrolyte circulation device, and a DC voltage is applied to the oxidation and reduction electrodes by the power source, the decomposition products of the alkaline aqueous solution in the anion exchange membrane, namely hydroxide ions (OH-), - The oxygen, water, and electrons are oxidized by the oxidizing catalyst on the surface of the oxidation electrode. The electrons move along the outer conductor to the reduction electrode, where they and water react with the catalyst on the surface of the reduction electrode to produce hydrogen gas and hydroxide ions (OH-). -The oxygen generated in the oxidation electrode and the hydrogen generated in the reduction electrode are discharged from the anion exchange membrane water electrolysis system through the oxidation electrode gas discharge system and the reduction electrode gas discharge system, respectively.

[0095] The anion exchange membrane water electrolysis system according to the present invention, having the above-described structure, is manufactured by the following method: after manufacturing an initial membrane-electrode assembly comprising an initial reduction electrode, an oxidation electrode, and an anion exchange membrane situated between the initial reduction electrode and the oxidation electrode, an alkaline aqueous solution is circulated and activated. During the activation process, the molar ratio of Ni to Mo and the oxidation number of Mo in the NiMo-based alloy particles at the initial reduction electrode change through the mechanism described above.

[0096] As described above, the preparation method of the anion exchange membrane water electrolysis system specifically includes: the steps of separately manufacturing an initial reduction electrode and an oxidation electrode (step 1); the step of manufacturing an initial membrane-electrode assembly by inserting an anion exchange membrane between the initial reduction electrode and the oxidation electrode (step 2); and the step of activating the initial reduction electrode by supplying an alkaline aqueous solution to the initial membrane-electrode assembly (step 3), wherein the initial reduction electrode comprises NiMo-based alloy particles, wherein the NiMo-based alloy particles comprise Ni and Mo in a molar ratio of 1:1 to 6:1, and the oxidation number of Mo is 4+, 5+, or 6+, and the initial reduction electrode is activated by supplying an alkaline aqueous solution to the initial membrane-electrode assembly at 25 mA / cm 2 Up to 200mA / cm 2 Activation is performed by applying a current density and maintaining the current at 50°C to 60°C for 90 to 360 minutes.

[0097] As explained in the following text, step 1 is the process of manufacturing the initial reduction electrode and the oxidation electrode, respectively.

[0098] The initial reduction electrode can be manufactured by a manufacturing method comprising the following steps: applying a slurry for forming the initial reduction electrode onto a release film, the slurry comprising NiMo-based alloy particles, a binder and a solvent; drying the slurry; and then separating the slurry from the release film.

[0099] The NiMo-based alloy particles included in the initial reduction electrode specifically contain Ni and Mo in a molar ratio of 1:1 to 6:1, wherein the oxidation number of Mo is 4+, 5+ or 6+.

[0100] More specifically, NiMo-based alloy particles may include Ni6Mo, Ni4Mo, Ni3Mo, or NiMo, and any one of them or a mixture of two or more of them may be used. More specifically, NiMo-based alloy particles may be Ni3Mo alloys, wherein Ni and Mo are included in a molar ratio of 3:1, and the oxidation number of Mo is 4+, 5+, or 6+.

[0101] The above-mentioned NiMo-based alloy particles can be prepared by powder method. Specifically, they can be prepared by a method including the following steps: co-precipitating Ni precursor and Mo precursor under alkaline conditions, and then heat-treating the resulting product.

[0102] As a Ni precursor, Ni-containing carbonates, nitrates, sulfates, acetates, hydroxides, chlorides, or hydrates can be used. Specific examples include nickel(II) chloride hexahydrate (NiCl2·6H2O), etc. Furthermore, as a Mo precursor, Mo-containing carbonates, nitrates, sulfates, acetates, hydroxides, or chlorides can be used. Specific examples include MoCl5, etc.

[0103] The mixing ratio of Ni precursor and Mo precursor can be appropriately determined based on the molar ratio of the elements in the prepared alloy.

[0104] Furthermore, the co-precipitation reaction of the Ni precursor and the Mo precursor takes place under alkaline conditions. For this purpose, one or more alkaline materials, such as sodium hydroxide (NaOH), sodium carbonate (Na₂CO₃), lithium hydroxide (LiOH), or potassium hydroxide (KOH), can be introduced. The alkaline material can be introduced in an amount that maintains an appropriate pH range for the co-precipitation reaction to occur; specifically, the pH is between 11 and 12.

[0105] In addition, alkaline materials can be added in the form of a solution phase dissolved in water.

[0106] Furthermore, the co-precipitation reaction of the Ni precursor and the Mo precursor can be carried out in a solvent. In this case, ultrapure water (DI water) or similar solvents can be used.

[0107] Specifically, a first solution is prepared by mixing Ni and Mo precursors, and a second solution of the alkaline material is prepared by dissolving the alkaline material in water. The water is then placed in separate reactors, and the first and second solutions are introduced to allow a co-precipitation reaction. Following the co-precipitation reaction of the Ni and Mo precursors, the reaction product is formed in the form of a precipitate.

[0108] The resulting reaction products are separated and then heat-treated in a mixed atmosphere of hydrogen and inert gas at 300°C to 500°C or 350°C to 450°C.

[0109] The reaction products are reduced by heat treatment. Furthermore, the degree of alloying and the size of the alloy particles can be adjusted by controlling the heat treatment temperature. In this invention, NiMo-based alloy particles that meet the above molar ratio and oxidation number requirements, and thus the particle size requirements, can be prepared by heat treatment under the aforementioned temperature conditions.

[0110] Additionally, during heat treatment, hydrogen can be included from 10% to 25% by volume, based on the total volume of the mixed gas. Nitrogen, argon (Ar), or similar inert gases can also be used. More specifically, heat treatment can be performed in an H2 / N2 atmosphere, where the total volume of the hydrogen and nitrogen mixture includes 10% hydrogen by volume.

[0111] When prepared using the above-described preparation method, the alloy is obtained in particulate form and has a relatively small average particle size and a wide specific surface area compared to NiMo-based alloys prepared by conventional methods such as electroplating or atomic deposition.

[0112] Specifically, the BET specific surface area of ​​the NiMo-based alloy particles is 30 m². 2 / g to 100m 2 / g, more specifically 35m 2 / g to 70m 2 / g.

[0113] In this invention, the BET specific surface area of ​​NiMo-based alloy particles can be tested using a Micromeritics Tristar II 3020 apparatus according to the Brunauer-Emmett-Teller (BET) method. Detailed test methods and conditions are described in the experimental examples below.

[0114] In addition, NiMo-based alloy particles are porous particles with multiple pores.

[0115] Specifically, the average pore size of the NiMo-based alloy particles is 5 nm to 20 nm, more specifically 9 nm to 16 nm, and the pore volume within the alloy particles is 0.1 cm³. 3 / g to 0.5cm 3 / g, more specifically 0.12cm 3 / g to 0.2cm 3 / g.

[0116] In addition, the average pore size and pore volume of NiMo-based alloy particles can be calculated from the nitrogen adsorption amount determined by the BET method. Detailed test methods and conditions are described in the experimental examples below.

[0117] Typically, NiMo-based alloys have a structure where Mo is located on the Ni surface, and the greater the amount of Mo present on the Ni surface, the higher the catalytic activity when used as a reduction catalyst in anion exchange membrane water electrolysis systems. However, in the case of NiMo-based alloys prepared by conventional electroplating or deposition methods, the amount of Mo present on the Ni surface is relatively small due to the large Ni particle size and small surface area. In contrast, the alloy particles of the present invention prepared by the above-described method have smaller Ni particle sizes than conventionally prepared alloy particles, resulting in a relatively larger specific surface area of ​​Ni, thus allowing for the presence of more Mo on the surface. Therefore, when Mo is lost due to subsequent contact with alkaline aqueous solutions, the Ni surface area can become wider, thereby exhibiting better catalytic activity.

[0118] On the other hand, the binders that can be used to prepare the slurry for forming the initial reduction electrode may include polytetrafluoroethylene (PTFE), perfluorosulfonic acid (PFSA), anion exchange resin or cation exchange resin, and any one of them or a mixture of two or more of them may be used.

[0119] Based on 100 parts by weight of NiMo-based alloy particles, the binder can be used in amounts of 20 to 50 parts by weight.

[0120] In addition, the solvent used to prepare the slurry for forming the initial reduction electrode may include water; or alcohol solvents, such as isopropanol, propanol and ethanol.

[0121] The slurry used to form the initial reduction electrode is applied to a release film, dried, and separated, thereby manufacturing the initial reduction electrode. The initial reduction electrode used in the water electrolysis system of the present invention consists only of a catalyst layer containing NiMo-based alloy particles, and typically does not include an electrode substrate for supporting the catalyst layer.

[0122] Meanwhile, the oxidation electrode includes the oxidation catalyst described above.

[0123] Oxidation electrodes can be manufactured using conventional methods for manufacturing oxidation electrodes. Specifically, similar to reduction electrodes, oxidation electrodes can be manufactured using a method that includes the following steps: mixing an oxidation catalyst with a binder and a solvent to prepare a slurry for forming the oxidation electrode; applying the slurry containing the oxidation catalyst, binder, and solvent to a release film; drying the slurry; and then separating the dried slurry from the release film. Alternatively, it can be manufactured using a method that includes the steps of coating, plating, or depositing an oxidation catalyst on an electrode substrate.

[0124] Next, step 2 is the step of manufacturing an initial membrane-electrode assembly by inserting an anion exchange membrane between the initial reduction electrode and the oxidation electrode manufactured in step 1.

[0125] Specifically, an initial membrane-electrode assembly can be fabricated by inserting the anion exchange membrane between the oxidation electrode and the initial reduction electrode, bringing the anion exchange membrane into contact with the catalyst layer of each electrode, and then bonding them together by applying heat and pressure. The bonding process using heat and pressure can be performed using conventional methods.

[0126] In addition, if the initial membrane-electrode assembly to be manufactured also includes a gasket, a further step of bonding the gasket to the manufactured assembly can be performed after the bonding steps of heat and pressure.

[0127] Meanwhile, the release film used in manufacturing the oxidation electrode and the initial reduction electrode can be separated after the bonding process is completed.

[0128] Meanwhile, the anion exchange membrane is the same as described above.

[0129] In addition, when the anion exchange membrane water electrolysis system includes multiple membrane-electrode assemblies, it may also include the step of repeating the process of manufacturing membrane-electrode assemblies two or more times to manufacture a stack, and then stacking the multiple membrane-electrode assemblies and joining them by applying pressure.

[0130] In addition to the membrane-electrode assembly, if the stack also includes a porous transport layer and a separator, the manufacturing process may include the following steps: placing the porous transport layer and the separator sequentially on the electrode side of the membrane-electrode assembly that is not in contact with the anion exchange membrane, and then joining the membrane-electrode assembly, the porous transport layer and the separator by applying pressure.

[0131] Next, step 3 is an activation step by supplying an alkaline aqueous solution to the initial membrane-electrode assembly manufactured in step 2.

[0132] An alkaline aqueous solution can be supplied to at least one of the initial reduction electrode and the oxidation electrode of the initial membrane-electrode assembly.

[0133] As described above, the alkaline aqueous solution can be supplied via an alkaline aqueous solution circulation device connected to the initial membrane-electrode assembly. Therefore, the preparation method of the present invention may further include, after the step of manufacturing the initial membrane-electrode assembly in step 2, connecting the alkaline aqueous solution circulation device to the initial membrane-electrode assembly.

[0134] For example, after the step of manufacturing the initial membrane-electrode assembly, the step may further include connecting an alkaline aqueous solution circulation device to the oxidation electrode of the initial membrane-electrode assembly, wherein the alkaline aqueous solution can be supplied from the alkaline aqueous solution circulation device to the oxidation electrode of the initial membrane-electrode assembly.

[0135] As another example, it may also include the step of connecting an alkaline aqueous solution circulation device for an initial reduction electrode and an alkaline aqueous solution circulation device for an oxidation electrode to the initial reduction electrode and oxidation electrode of the initial membrane-electrode assembly, respectively, after manufacturing the initial membrane-electrode assembly, wherein the alkaline aqueous solution can be supplied from the alkaline aqueous solution circulation device for the initial reduction electrode and the alkaline aqueous solution circulation device for the oxidation electrode to the initial reduction electrode and oxidation electrode of the initial membrane-electrode assembly, respectively.

[0136] As another example, it may also include the step of installing an alkaline aqueous solution circulation device after manufacturing the initial membrane-electrode assembly to connect it to both the initial reduction electrode and the oxidation electrode of the initial membrane-electrode assembly, wherein the alkaline aqueous solution can be supplied from the alkaline aqueous solution circulation device to the initial reduction electrode and the oxidation electrode of the initial membrane-electrode assembly.

[0137] In this invention, since the initial reduction electrode becomes a reduction electrode after activation, the alkaline aqueous solution circulation device for the initial reduction electrode connected to the initial reduction electrode is called an alkaline aqueous solution circulation device for the reduction electrode after activation.

[0138] The alkaline aqueous solution, as described above, can more specifically be an aqueous solution of potassium hydroxide with a concentration of 0.1M to 1M.

[0139] Through the activation process, the molar ratio of Ni to Mo and the oxidation number of Mo in the NiMo-based alloy particles change. The activation conditions during the activation process, especially the current and time, affect the performance development mechanism of the aforementioned NiMo-based alloy. Therefore, in this invention, the composition of a NiMo alloy exhibiting excellent performance was determined, and the activation conditions that can achieve this alloy composition were discovered and optimized.

[0140] Specifically, this can be achieved by applying a current density of 25 mA / cm². 2 Up to 200mA / cm 2 Activation is achieved by applying a current and maintaining that current at 50°C to 60°C for 90 to 360 minutes. More specifically, this can be done by applying a current density of 50 mA / cm². 2 Up to 100mA / cm 2 The current is applied and maintained at 50°C to 60°C for 300 to 360 minutes to activate the device.

[0141] When activated under the above conditions, NiMo-based alloy catalysts that meet the above molar ratio and oxidation number requirements can be prepared, resulting in excellent water electrolysis performance.

[0142] Specifically, although the molar ratio of Ni to Mo in the NiMo-based alloy particles before activation is 1:1 to 6:1 (Ni:Mo), due to the loss of Mo during the activation process, the molar ratio of Ni to Mo in the activated NiMo-based alloy catalyst becomes 6:1 to 101:1.

[0143] Furthermore, although the oxidation number of Mo in the NiMo-based alloy particles before activation is 4+, 5+, or 6+, it becomes 5+ or 6+ after activation. This is because the oxidation number of Mo changes during the activation process through the mechanism described above.

[0144] In addition, due to the loss of Mo during the activation process, a Ni layer composed of Ni is formed on the surface of the activated alloy catalyst and on the surface of the reduction electrode including the alloy catalyst.

[0145] In addition, the preparation method of the present invention may also include a step of testing battery performance to test the performance of the activated anion exchange membrane water electrolysis system.

[0146] Specifically, the battery performance testing can be performed by measuring the current density for each range from 1.45V to 1.9V in 0.05V increments for 10 seconds.

[0147] The steps for testing battery performance are designed to assess the performance of the anion exchange membrane water electrolysis system without affecting the activation results and battery performance.

[0148] The anion exchange membrane water electrolysis system prepared by the above method exhibits improved durability and efficiency as well as excellent water electrolysis performance.

[0149] According to another embodiment of the present invention, an activation method is provided that can improve the performance of anion exchange membrane water electrolysis system.

[0150] Specifically, the method for activating anion exchange membrane water electrolysis system includes the following steps: activating the initial reduction electrode by supplying an alkaline aqueous solution to the initial anion exchange membrane water electrolysis system comprising an initial reduction electrode, an oxidation electrode, and an anion exchange membrane between the initial reduction electrode and the oxidation electrode, wherein the initial reduction electrode comprises NiMo-based alloy particles in which the molar ratio of Ni to Mo is 1:1 to 6:1 and the oxidation number of Mo is 4+, 5+, or 6+, and activation is performed by applying an alkaline aqueous solution to the initial reduction electrode at a flow rate of 25 mA / cm². 2 Up to 200mA / cm 2The current density is applied and the current is maintained at 50°C to 60°C for 90 minutes to 360 minutes.

[0151] Details of the initial anion exchange membrane water electrolysis system, the alkaline aqueous solution and its supply method and activation process are as described above.

[0152] In addition, the result of activating the initial reduction electrode is the preparation of a reduction electrode comprising a NiMo-based alloy catalyst in which the molar ratio of Ni to Mo is 6:1 to 101:1 and the oxidation number of Mo is 5+ or 6+.

[0153] In the following description, preferred exemplary embodiments are provided for a better understanding of the invention. However, the following exemplary embodiments are for illustrative purposes only, and the invention is not limited thereto.

[0154] <Preparation of NiMo-based alloy particles> Preparation Example 1 The first solution was prepared by dissolving NiCl₂·6H₂O and MoCl₅ in 20 mL of DI water to a total concentration of 15 mmol. In this case, NiCl₂·6H₂O and MoCl₅ were used in a Ni:Mo molar ratio of 1:1.

[0155] In addition, a second solution was prepared by dissolving 34.2 mmol NaOH solution and 10.7 mmol Na2CO3 in 20 mL DI water.

[0156] Add 40 mL of DI water to a vial, and add and mix the first and second solutions dropwise while stirring. Mix at room temperature (23 ± 2 °C) and maintain the pH of the mixed solution below 8.5.

[0157] The mixed solution was reacted with stirring for 24 hours, and the metal precipitate was obtained by centrifugation. The obtained metal precipitate was washed three times with water and ethanol, and dried overnight in a convection oven at 50°C.

[0158] NiMo alloy particles were prepared by reducing 300 mg of the obtained dry material at 400 °C for 1 hour in a 10% H2 / N2 atmosphere.

[0159] Preparation Example 2 Ni3Mo alloy particles were prepared in the same manner as in Preparation Example 1, except that NiCl2·6H2O and MoCl5 were used in a Ni:Mo molar ratio of 3:1 when preparing the first solution in Preparation Example 1.

[0160] Preparation Example 3 Ni4Mo alloy particles were prepared in the same manner as in Preparation Example 1, except that NiCl2·6H2O and MoCl5 were used in a Ni:Mo molar ratio of 4:1 when preparing the first solution in Preparation Example 1.

[0161] Preparation Example 4 Ni6Mo alloy particles were prepared in the same manner as in Preparation Example 1, except that when preparing the first solution in Preparation Example 1, NiCl2·6H2O and MoCl5 were used in a Ni:Mo molar ratio of 6:1.

[0162] <Manufacturing of a Water Electrolysis System> Example 1 An anion exchange membrane water electrolysis system was fabricated using the NiMo alloy particles prepared in Preparation Example 1.

[0163] In detail, the manufacturing process is carried out in the following order: electrode manufacturing step, membrane-electrode assembly manufacturing step, KOH solution supply system configuration step, and activation step.

[0164] Electrode manufacturing steps The NiMo alloy particles and binder prepared in Preparation Example 1 were dispersed in a solvent, subjected to ultrasonication for 30 minutes, and then dispersed using a ball mill to prepare a slurry for forming the initial reduction electrode. In this case, the NiMo alloy particles and binder were used at a weight ratio of 1:0.2, and 60% by weight of a polytetrafluoroethylene (PTFE) aqueous dispersion was used as the binder. Additionally, a mixed solvent of water and isopropanol (IPA) at a weight ratio of 5:5 was used as the solvent, with the amount of solvent used such that the solid content in the slurry for forming the initial reduction electrode was 20% by weight.

[0165] The prepared slurry for forming the initial reduced electrode was applied using a doctor blade coater with a dried NiMo loading of 1.0 mg / cm³. 2 The material was coated onto a release film using the above method and dried in a convection oven at 80°C for 1 hour to prepare the initial reduced electrode. XRF analysis confirmed that the NiMo loading was 1.0 mg / cm³. 2 above.

[0166] Independently, the oxidation electrode was prepared in the same manner as described above, except that NiFe layered double hydroxide (NiFe LDH) was used as a catalyst.

[0167] Manufacturing steps of membrane-electrode assembly The component is fabricated by bonding the electrode to the anion exchange membrane using the catalyst-coated membrane (CCM) method.

[0168] The initial reduction and oxidation electrodes, fabricated in the electrode manufacturing step, are cut into 3 cm wide and 3 cm long pieces. A Sustainion™ X37-50 grade RT anion exchange membrane is then inserted between the initial reduction and oxidation electrodes and rolled at 0.1 m / min under 130°C and 30 MPa pressure to obtain the initial membrane-electrode assembly. The release membrane is then removed from the initial reduction and oxidation electrodes. A 200 μm thick sub-gasket is attached to the fabricated initial membrane-electrode assembly to prevent battery leakage and facilitate handling.

[0169] Activation steps A lower end plate made of steel-use stainless steel (SUS) is prepared, and a Ni-made oxide electrode separator, a 300 μm thick porous transport layer (PTL) of nickel foam serving as the oxide electrode, and the aforementioned initial membrane-electrode assembly are stacked on it, such that the oxide electrode is in contact with the porous transport layer. A 250 μm thick carbon paper serving as the porous transport layer for the reduction electrode, a Ni-made reduction electrode separator, and an upper end plate made of SUS are sequentially placed on the reduction electrode side of the initial membrane-electrode assembly and fastened by applying a pressure of 7 Nm to obtain the stack.

[0170] Two KOH tanks were prepared as alkaline aqueous solution circulation devices and connected to the oxidation and reduction electrodes of the battery stack, respectively, to obtain a dual-supply type initial anion exchange membrane water electrolysis system in which KOH is supplied to both the oxidation and reduction electrodes. In this case, a 1M KOH aqueous solution was used as the alkaline aqueous solution.

[0171] For the prepared initial anion exchange membrane water electrolysis system, KOH was supplied via a dual-supply method. The KOH aqueous solution was maintained at 50°C and circulated at a rate of 10 cc / min. When the initial anion exchange membrane water electrolysis system reached 50°C, a power supply of 50 mA / cm² was applied to the system. 2 The battery was activated by applying a current density of 6 hours, and its performance was then tested by measuring the current density in each range from 1.45V to 1.9V for 10 seconds in increments of 0.05V. This method yielded an anion exchange membrane water electrolysis system.

[0172] Examples 2 to 4 Each anion exchange membrane water electrolysis system was manufactured in the same manner as in Example 1, except that the alloy particles prepared in Preparation Examples 2 to 4 were used as alloy particles.

[0173] Experimental Example 1 For the alloy particles prepared in Preparation Examples 1 to 4, the BET specific surface area, average pore size, and average pore volume were tested using the following method.

[0174] According to the Brunauer-Emmett-Teller (BET) method, nitrogen gas was adsorbed onto the alloy particles prepared in Examples 1 to 4 at liquid nitrogen temperature (77 K) using a Micromeritics Tristar II 3020. The amount of nitrogen adsorbed was then measured, and the specific surface area, pore volume, and pore size were calculated. The test results are shown in Table 1 below. Figures 6A to 6D middle.

[0175] Figures 6A to 6D The figures shown are BET analysis results of the NiMo-based alloy particles prepared in Examples 1, 2, 3, and 4.

[0176] Table 1

[0177] As a result of the experiment, the NiMo-based alloy particles prepared in Examples 1 to 4 have a particle size of 37 μm. 2 / g to 66m 2 The BET specific surface area of ​​ / g and the pore size of 9nm to 16nm indicate that they have increased pore size and pore volume as well as a wide BET specific surface area compared to those alloys prepared by conventional deposition or electroplating methods.

[0178] Experiment Example 2 Linear sweep voltammetry (LSV) was used to evaluate the hydrogen evolution reaction activity as a function of the molar ratio of Ni to Mo in NiMo-based alloys.

[0179] LSV was performed in a 3-electrode cell using a CH Instruments CHE760E dual potentiostat.

[0180] A catalyst slurry for the working electrode was prepared by mixing 10 mg of NiMo-based alloy particles, 1 mL of deionized water, 1.5 mL of 2-propanol, and 60 μL of a 5% by weight Nafion solution. The alloy particles prepared in Examples 1 to 4 were used as the NiMo-based alloy. The 10 μL of the prepared catalyst slurry was then mixed with 0.2 mg / cm³ of water. 2 The amount of the substance was loaded onto a glassy carbon rotating disk electrode (RDE) and the LSV was measured in 1M KOH solution using a reversible hydrogen electrode (RHE) with a voltage range of 0.15V to -0.3V.

[0181] In addition, for comparison, the change in hydrogen evolution reaction activity of 40 wt% Pt / C was evaluated in the same manner as above, except that the loading was changed to 0.04 mg / cm³. 2 and 0.2 mg / cm2 In addition, 40wt% Pt / C is a catalyst traditionally used as an oxidation electrode.

[0182] In addition, the initial oxidation number of Mo in the NiMo-based alloys prepared in Examples 1 to 4 used in this experimental example was tested by X-ray photoelectron spectroscopy (XPS).

[0183] In detail, the composition of Ni3Mo alloy particles in the initial anion exchange membrane water electrolysis system and the composition of the electrode surfaces in the anion exchange membrane water electrolysis system were determined using Thermo Scientific K-alpha X-ray photoelectron spectroscopy from Thermo Fisher Scientific. To correct for the binding energy, it was set to 284.6 eV based on the C1s peak.

[0184] The test results are shown in Figure 7 and Figure 8 middle.

[0185] Figure 7 This is a graph showing the results of linear sweep voltammetry (LSV) used to evaluate the hydrogen evolution reaction activity as a function of the molar ratio of Ni to Mo in NiMo-based alloys. Figure 8 This is a graph showing the XPS results of analyzing the initial oxidation number of Mo in the NiMo-based alloys prepared in Examples 1 to 4.

[0186] The experimental results confirmed that NiMo-based alloy particles exhibited the best catalytic activity when the Ni to Mo ratio was 3:1 to 4:1, at which point the oxidation number of Mo was 4+, 5+, or 6+.

[0187] Experimental Example 3 To detect the loss of Mo in NiMo-based alloys under alkaline conditions, an anion exchange membrane water electrolysis system was fabricated using Ni3Mo alloy particles prepared in Preparation Example 2, and the change in the molar ratio of Ni and Mo in the alloy before and after activation was evaluated.

[0188] In detail, ten initial anion exchange membrane water electrolysis systems were manufactured in the same manner as in Example 1, except that the Ni3Mo alloy particles prepared in Preparation Example 2 were used as NiMo-based alloy particles (sample numbers 1 to 10). The NiMo content and the Ni and Mo content in the alloy were determined in the manufactured initial anion exchange membrane water electrolysis systems.

[0189] For the initial anion exchange membrane water electrolysis systems manufactured above, 1M KOH solution was circulated at 50°C while maintaining a current of 25 mA / cm². 2The current was applied for 6 hours to activate it. Then, a power supply was used to maintain the voltage from 1.45V to 1.9V for 10 seconds in increments of 0.05V. The battery performance was tested by measuring the current density in each range, thus obtaining various anion exchange membrane water electrolysis systems.

[0190] The content of the NiMo alloy catalyst and the content of Ni and Mo in the alloy were tested for the prepared anion exchange membrane water electrolysis system.

[0191] The content of NiMo and the content of Ni and Mo in the alloy were determined by X-ray fluorescence spectrometry (XRF).

[0192] In detail, using the Olympus VANTA S as the XRF instrument, elemental analysis was performed by irradiating the material with X-rays ranging from 0 keV to 40 keV. The peaks that appeared during this irradiation were analyzed to identify the material. Additionally, the X-ray irradiation time was held for 10 seconds, and calibration curves of the peaks appearing at this time were plotted to analyze the content. Each calibration curve was calculated using software built into the XRF instrument.

[0193] The results are shown in Table 2 below.

[0194] Table 2

[0195] The experimental results confirmed the significant loss of Mo after activation. It also confirmed that the molar ratio of Ni to Mo in NiMo-based alloys changed due to this loss.

[0196] Furthermore, the cause of Mo loss was investigated through thermodynamic calculations.

[0197] Table 3 below shows the loss energy of Mo in NiMo-based alloy catalysts.

[0198] Table 3

[0199] As shown in Table 3, when calculating Mo from Ni 24 When the energy of each element is lost in the Mo8 alloy, it can be seen that all the progress is toward stability, and computational chemistry shows that the NiMo-based alloy is stable when all the Mo present on the surface is lost in an alkaline environment.

[0200] The H2O, MoO2, and H2O / MoO2 clusters in Ni were calculated. 24 The adsorption energy on the surface of the Mo8 alloy indicates that the lost Mo is adsorbed by water and exists in the form of H2O / MoO2.

[0201] Furthermore, the adsorption energies corresponding to the adsorption sites of the hydrogen intermediate H* were calculated, revealing that the hydrogen intermediate is stable when adsorbed at Ni sites rather than Mo sites. Therefore, it can be expected that MoO2 and H2O clusters adsorb on the Ni surface, and that after water electrolysis, hydrogen migrates to the Ni surface to generate hydrogen.

[0202] The results above indicate that the hydrogen evolution reaction mechanism of Ni-Mo alloy in alkaline environment is that all Mo on the surface of Ni-Mo alloy is lost, the lost Mo forms Mo oxide, and then is re-adsorbed onto the bare Ni surface in the form of H2O / Mo oxide. Then, water dissociation reaction and adsorption of hydrogen intermediate H* at Ni site (dual active site) occur, and H2 is generated through Heyrovsky or Tafel reaction.

[0203] Therefore, the stable and highly active NiMo alloy structure in an alkaline environment has a surface composed of Ni, because only the Mo on the surface is selectively dissolved, and the dissolved Mo forms clusters with H2O in the form of Mo oxide MoO2, and must be adsorbed onto the Ni surface, wherein the molar ratio of Ni to Mo is 6:1 to 101:1.

[0204] Experiment Example 4 The changes in the Mo oxidation number in NiMo-based alloys before and after activation were evaluated.

[0205] In detail, the initial anion exchange membrane water electrolysis system was manufactured in the same manner as in Example 1, except that the Ni3Mo alloy particles prepared in Preparation Example 2 were used as the NiMo-based alloy particles. The Mo oxidation number of the Ni3Mo alloy particles in the manufactured initial anion exchange membrane water electrolysis system was tested.

[0206] For the initial anion exchange membrane water electrolysis system manufactured above, 1M KOH solution is circulated at 50°C while maintaining a current of 50 mA / cm². 2 The anion exchange membrane water electrolysis system was activated by applying a current for 6 hours. Then, a power supply was used to maintain a voltage from 1.45V to 1.9V for 10 seconds in increments of 0.05V. The battery performance was assessed by measuring the current density within each range. The Mo oxidation number of the alloy catalyst in the fabricated anion exchange membrane water electrolysis system was also tested.

[0207] The oxidation number of Mo was determined by X-ray photoelectron spectroscopy (XPS), using the same methods and conditions as in Experimental Example 2. The results are shown below. Figure 9 middle.

[0208] Figure 9 This is a graph showing the XPS results of the analysis of the change in the oxidation number of Mo in the Ni3Mo alloy before and after activation.

[0209] The experiment showed that the oxidation numbers of Mo in the Ni3Mo alloy before activation were 4+, 5+, and 6+, while after activation they were 5+ and 6+. This confirms that the oxidation number of Mo in NiMo-based alloys changes in an alkaline environment.

[0210] Experimental Example 5 The effects of activation methods on the performance of anion exchange membrane water electrolysis systems were evaluated.

[0211] In detail, the initial anion exchange membrane water electrolysis system was manufactured in the same manner as in Example 1, except that the Ni3Mo alloy particles prepared in Preparation Example 2 were used as NiMo-based alloy particles. Then, while supplying an alkaline aqueous solution to the manufactured initial anion exchange membrane water electrolysis system, activation was performed by an activation method that increases or decreases the applied voltage as in the prior art (hereinafter referred to as "Comparative Example"), and an activation method that applies current while maintaining a constant current density as in the present invention (hereinafter referred to as "Example").

[0212] (1) Activation method 1 (Comparative example A) For the initial anion exchange membrane water electrolysis system manufactured above, a 1M KOH solution was circulated at 60°C. The voltage was increased from 1.45V to 1.9V in increments of 0.05V, held for 5 seconds, and then decreased from 1.9V to 1.45V in increments of 0.05V, held for 5 seconds. To maintain the current density, the number of activation cycles (voltage increases and decreases) was fixed at 20.

[0213] (2) Activation method 2 (Example A) The initial anion exchange membrane water electrolysis system manufactured above was activated by circulating a 1M KOH solution at 60°C and maintaining a flow rate of 100 mA / cm². 2 The current is applied continuously for 6 hours.

[0214] After activation using the above method, the battery performance of each anion exchange membrane water electrolysis system was tested by measuring the current density within each range from 1.45V to 1.9V in 0.05V increments for 10 seconds. Simultaneously, the change in current with voltage control was observed during the battery performance testing. The results are shown below. Figure 10 and Figure 11 middle.

[0215] Figure 10 This is a graph showing the results of the change in current as a function of voltage control observed in an anion exchange membrane water electrolysis system activated by increasing or decreasing the applied voltage. Figure 11This is a graph showing the results of the change in current as a function of voltage control observed in an anion exchange membrane water electrolysis system activated by applying a current at a predetermined current density and maintaining that current for a predetermined time.

[0216] The experimental results showed that the conventional activation method (Comparative Example A), which involved increasing or decreasing the applied voltage, accelerated the loss of Mo upon voltage variation, resulting in a sharp decline in water electrolysis performance. Conversely, at a voltage of 100 mA / cm², the traditional activation method accelerated the loss of Mo, resulting in a sharp decline in water electrolysis performance. 2 In the activation method (Example A) where a current density is applied and maintained for 6 hours, since Mo is lost at the beginning of activation and then redeposited on the Ni surface, it was confirmed that the performance remained constant and unchanged even if the voltage change was repeated more than 10 times.

[0217] Experimental Example 6 The effect of activation method on Mo loss in anion exchange membrane water electrolysis system was evaluated.

[0218] (1) Activation Method 1 (Comparative Example B) An initial anion exchange membrane water electrolysis system was prepared in the same manner as in Example 1, except that the Ni3Mo alloy particles prepared in Preparation Example 2 were used as the NiMo-based alloy particles. Then, for the prepared initial anion exchange membrane water electrolysis system, a 1M KOH solution was circulated at 60°C, and the voltage was increased from 1.45V to 1.9V in increments of 0.05V, held for 5 seconds, and then decreased from 1.9V to 1.45V in increments of 0.05V, held for 5 seconds. The number of cycles was kept constant to maintain the current density.

[0219] Then, after activation, the battery performance of each anion exchange membrane water electrolysis system was tested by using a power supply maintained at 1.45V to 1.9V for 10 seconds in increments of 0.05V, thus obtaining the anion exchange membrane water electrolysis system.

[0220] (2) Activation method 2 (Example B) The initial anion exchange membrane water electrolysis system was manufactured in the same manner as in Example 1, except that the Ni3Mo alloy particles prepared in Preparation Example 2 were used as the NiMo-based alloy particles. The initial anion exchange membrane water electrolysis system was then activated by circulating a 1M KOH solution at 60°C and maintaining a current of 50 mA / cm². 2 The current was applied for 6 hours. Then, the battery performance was tested by using a power supply maintained at 1.45V to 1.9V for 10 seconds in increments of 0.05V to test the current density in each range, thus obtaining the anion exchange membrane water electrolysis system.

[0221] The contents of NiMo alloy and Mo in the initial anion exchange membrane water electrolysis system before activation and the contents of residual NiMo alloy and Mo in the electrodes of the activated anion exchange membrane water electrolysis system were determined by X-ray fluorescence spectroscopy (XRF).

[0222] At this point, X-ray fluorescence spectrometry (XRF) and content testing were performed in the same manner as in Experimental Example 3.

[0223] As a result of the experiment, the initial Mo content in the NiMo alloy before activation was 0.75 mg / cm³. 2 (The catalyst reaction area is 5 cm²) 2 When activated using activation method 1 (Comparative Example B), the content of Mo after activation was 0.07 mg / cm³. 2 This indicates that approximately 9% remains. In contrast, when activated using activation method 2 (Example B), the initial Mo content was 0.75 mg / cm³. 2 After activation, the concentration is 0.18 mg / cm³. 2 This indicates that approximately 24% remains.

[0224] This confirms that the activation method of the present invention is more advantageous in reducing Mo loss, and as a result, it can improve the lifespan characteristics of the water electrolysis system.

[0225] Experimental Example 7 To evaluate the effect of current conditions during the activation process on the performance development mechanism of NiMo-based alloys, the current density was varied to 25 mA / cm². 2 50mA / cm 2 100mA / cm 2 and 200mA / cm 2 To activate and evaluate performance.

[0226] In detail, the initial anion exchange membrane water electrolysis system was manufactured in the same manner as in Example 1, except that the Ni3Mo alloy particles from Preparation Example 2 were used. The electrolysis was performed at 25 mA / cm². 2 50mA / cm 2 100mA / cm 2 and 200mA / cm 2 The initial anion exchange membrane water electrolysis system was activated by applying a current for 6 hours under the specified current density conditions while circulating a 1M KOH solution at 50°C. The battery performance was then tested by measuring the current density in various ranges from 1.45V to 2.5V for 10 seconds in increments of 0.05V, thus completing the anion exchange membrane water electrolysis system.

[0227] For comparison, an initial anion exchange membrane water electrolysis system was fabricated using 40 wt% Pt / C catalyst as the catalyst for the reduction electrode, in the same manner as in Example 1. The fabricated initial anion exchange membrane water electrolysis system was activated by circulating 1 MkOH solution at 50°C, increasing the voltage from 1.45 V to 1.9 V in 0.05 V increments while holding for 5 seconds, and then decreasing the voltage from 1.9 V to 1.45 V in 0.05 V increments while holding for 5 seconds. The number of cycles was kept constant to maintain the current density. The battery performance was then tested using the same method as described above, thus obtaining the anion exchange membrane water electrolysis system.

[0228] For the anion exchange membrane water electrolysis system manufactured above, the change of voltage with current density was tested using the linear sweep voltammetry (LSV) method, and the polarization curve was obtained.

[0229] In detail, for each of the anion exchange membrane water electrolysis systems manufactured above, the voltage variation with current density was tested under LSV conditions using a CH Instruments CHE760E dual potentiostat. The results are shown in... Figure 12 middle.

[0230] In addition, the durability of the anion exchange membrane water electrolysis system manufactured above was evaluated using the chronoamperometry method.

[0231] In detail, for each of the anion exchange membrane water electrolysis systems manufactured above, a power source is used to maintain a current density of 1 A / cm². 2 Simultaneously, the voltage was measured. When the voltage remained constant, durability was rated as excellent; when the voltage increased, durability was rated as low. The results are shown in... Figure 13 middle.

[0232] Figure 12 This shows the values ​​at 25 mA / cm. 2 50mA / cm 2 100mA / cm 2 and 200mA / cm 2 The figure shows the polarization evaluation results of the activated anion exchange membrane water electrolysis system under the specified current density conditions. Figure 13 This shows the values ​​at 25 mA / cm. 2 50mA / cm 2 100mA / cm 2 and 200mA / cm 2 The figure shows the durability evaluation results of the activated anion exchange membrane water electrolysis system under the current density conditions.

[0233] The experimental results confirmed that when the current is 25 mA / cm 2 Up to 200mA / cm 2When activated by a current density of 50 mA / cm², the system exhibits excellent performance characteristics, especially at that current density. 2 When activated by a high current density, it exhibits better performance and durability than platinum.

[0234] Furthermore, the reasons for the above experimental results can be understood through the Pourbaix diagram.

[0235] Figure 14 It is a graph showing the state of Mo as a function of pH, published in the reference "Anatolyevich, Pavel. "The Revised Pourbaix Diagram for Molybdenum." HMo 2.10: 3".

[0236] like Figure 14 As shown, it can be seen that Mo in an alkaline environment and within a specific current range exists as MoO4. 2- It may exist in the form of MoO2. Furthermore, under conditions above pH 12, Mo exists as MoO4. 2- Mo is lost in the form of dissolution. However, as shown in line 26, Mo can exist as MoO2 within a specific voltage range between pH 9 and pH 12. Experimental and computational chemistry demonstrate that Mo can exist as MoO2 when activated within a specific current range, and it can be predicted that at 50 mA / cm², MoO2 can exist as MoO2. 2 When activated, Mo is very likely to exist in the form of MoO2.

[0237] In addition, the effect of current conditions during activation on Mo loss in NiMo-based alloys in an alkaline environment was evaluated.

[0238] By changing the current density to 25 mA / cm 2 50mA / cm 2 100mA / cm 2 and 200mA / cm 2 The activated anion exchange membrane water electrolysis system was tested for Mo residue by X-ray spectroscopy (XRF) in the same manner as in Experimental Example 3.

[0239] The results are shown in Figure 15 middle.

[0240] Figure 15 This shows the results at 25 mA / cm. 2 50mA / cm 2 100mA / cm 2 and 200mA / cm 2The figure shows the results of X-ray fluorescence spectrometry (XRF) analysis of the residual Mo in an anion exchange membrane water electrolysis system activated under certain current density conditions.

[0241] As a result of the experiment, when at 50 mA / cm 2 At a current density of [value missing], the maximum amount of Mo is retained in the cathode. Therefore, it can be predicted that the Mo lost during activation is re-adsorbed onto the Ni surface.

[0242] Experimental Example 8 To evaluate the effect of activation time on the performance development mechanism of NiMo-based alloys, activation times were changed to 90 minutes, 180 minutes, and 360 minutes, respectively, and the battery performance was evaluated.

[0243] In detail, the initial anion exchange membrane water electrolysis system was manufactured in the same manner as in Example 1, except that the Ni3Mo alloy particles from Preparation Example 2 were used. This was achieved by circulating a 1M KOH solution at 50°C at a current of 50 mA / cm². 2 The initial anion exchange membrane water electrolysis system was activated by applying current at various current densities for 90 minutes, 3 hours, and 6 hours. The battery performance was then tested by measuring current densities ranging from 1.45V to 1.9V in 0.05V increments for 10 seconds, thus completing the anion exchange membrane water electrolysis system.

[0244] Furthermore, for comparison, an initial anion exchange membrane water electrolysis system was fabricated using 40 wt% Pt / C catalyst as the catalyst for the reduction electrode, in the same manner as in Example 1. The fabricated initial anion exchange membrane water electrolysis system was activated by cycling a 1M KOH solution at 50°C, increasing the voltage from 1.45V to 1.9V in 0.05V increments while holding for 5 seconds, and then decreasing the voltage from 1.9V to 1.45V in 0.05V increments while holding for 5 seconds. The cycling was then fixed at 10 cycles to maintain the current density. The battery performance was then tested by measuring the current density in various ranges from 1.45V to 1.9V and holding for 10 seconds using a power supply in 0.05V increments.

[0245] For the anion exchange membrane water electrolysis system manufactured above, the chronoamperometry method is used, maintaining 1 A / cm 2 The voltage value was tested under the given conditions. The results are shown in... Figure 16 middle.

[0246] Figure 16 This is a graph showing the evaluation results of the effect of activation time on the performance development of NiMo-based alloys.

[0247] The results of the experiment showed that when the activation time was 180 minutes or longer, it achieved higher performance than platinum, and when the activation time was 360 minutes or longer, it was stable.

[0248] Experimental Example 9 The variation of Mo loss in an anion exchange membrane water electrolysis system with the circulation mode of alkaline aqueous solution was evaluated.

[0249] Using the Ni3Mo alloy particles prepared in Preparation Example 2, a process was fabricated as follows: Figure 4 The illustrated initial anion exchange membrane water electrolysis system includes a shared-supply type alkaline aqueous solution circulation device, such as... Figure 5 The diagram shows an initial anion exchange membrane water electrolysis system including an anode-supply type alkaline aqueous solution circulation device. The NiMo content in the manufactured initial anion exchange membrane water electrolysis system, as well as the Ni and Mo content in the alloy, were tested separately.

[0250] Subsequently, by applying 25 mA / cm 2 The initial anion exchange membrane water electrolysis system was activated by applying a current for 6 hours while simultaneously circulating a 1M KOH solution at 60°C. The battery performance was tested by measuring the current density across a range from 1.45V to 1.9V in 0.05V increments for 10 seconds. The content of the NiMo alloy catalyst and the Ni and Mo content in the alloy within the prepared anion exchange membrane water electrolysis system were also tested.

[0251] The NiMo content and the Ni and Mo content in the alloy were determined by X-ray fluorescence spectrometry (XRF) in the same manner as in Experimental Example 3. The results are shown in Table 4 below.

[0252] Table 4

[0253] As a result of the experiment, the anodic supply method, which supplies only to the oxidation electrode side, resulted in a lower Mo loss rate compared to the shared supply method, which simultaneously supplies KOH solution.

[0254] In the shared-supply mode, the dissolution of Mo, which occurs when the KOH solution is in direct contact with the NiMo catalyst, and the dissolution of Mo that is anionized and moves to the anode occur simultaneously. In contrast, the anode-supply mode exhibits a lower dissolution rate than the shared-supply mode because the NiMo catalyst is not in direct contact with KOH.

[0255] Experimental Example 10 The effect of alkaline aqueous solution circulation mode on the performance of anion exchange membrane water electrolysis system was evaluated.

[0256] Using the Ni3Mo alloy particles prepared in Preparation Example 2, a process was fabricated as follows: Figure 4 The diagram shows an initial anion exchange membrane water electrolysis system including a shared-supply alkaline aqueous solution circulation device and an initial anion exchange membrane water electrolysis system including a dual-supply alkaline aqueous solution circulation device, as shown in Figure 6.

[0257] Subsequently, by applying 25 mA / cm 2 The initial anion exchange membrane water electrolysis system was activated by applying a current for 6 hours while simultaneously circulating a 1M KOH solution at 60°C. The battery performance was tested by measuring the current density in each range from 1.45V to 1.9V for 10 seconds in 0.05V increments, thus preparing each anion exchange membrane water electrolysis system.

[0258] For each of the anion exchange membrane water electrolysis systems manufactured above, the voltage change with current density was tested by linear sweep voltammetry (LSV), and the polarization curves were obtained.

[0259] In detail, for each of the anion exchange membrane water electrolysis systems manufactured above, the change of voltage with current density was tested under LSV conditions using a device (CHE760E dual potentiostat manufactured by CH Instruments).

[0260] In addition, the durability of the anion exchange membrane water electrolysis system manufactured above was evaluated using the chronoamperometry method.

[0261] In detail, for each of the anion exchange membrane water electrolysis systems manufactured above, a power source is used to maintain a current density of 1 A / cm². 2 Simultaneously, the voltage was tested. When the voltage remained constant, durability was rated as excellent; as the voltage increased, durability was rated as low. The results are shown in... Figure 17 and Figure 18 middle.

[0262] Figure 17 This is a graph showing the results of evaluating the polarization of anion exchange membrane water electrolysis system based on the alkaline aqueous solution circulation method. Figure 18 This is a graph showing the evaluation results of the durability of the anion exchange membrane water electrolysis system.

[0263] As a result of the experiment, compared with the dual-supply method using a single tank to supply KOH aqueous solution, the independently configured shared supply method can generate hydrogen at a lower voltage. In other words, it confirms that the system efficiency is higher when the KOH aqueous solution supply is configured to be separate for the anode and cathode.

Claims

1. A method for preparing an anion exchange membrane water electrolysis system, the method comprising the following steps: The initial reduction electrode and oxidation electrode were manufactured separately; An initial membrane-electrode assembly is fabricated by inserting an anion exchange membrane between the initial reduction electrode and the initial oxidation electrode. and The initial reduction electrode is activated by supplying an alkaline aqueous solution to the initial membrane-electrode assembly. The initial reduction electrode comprises NiMo-based alloy particles, wherein the molar ratio of Ni to Mo in the NiMo-based alloy particles is 1:1 to 6:1, and the oxidation number of Mo is 4+, 5+, or 6+. The activation is performed at 25 mA / cm 2 Up to 200mA / cm 2 The current density is applied and the current is maintained at 50°C to 60°C for 90 minutes to 360 minutes.

2. The method for preparing the anion exchange membrane water electrolysis system according to claim 1, wherein, The activation is performed at 50 mA / cm 2 Up to 100mA / cm 2 The current density is applied and the current is maintained at 50°C to 60°C for 300 to 360 minutes.

3. The method for preparing the anion exchange membrane water electrolysis system according to claim 1, wherein, The alkaline aqueous solution is supplied to either the initial reduction electrode or the oxidation electrode of the initial membrane-electrode assembly.

4. The method for preparing the anion exchange membrane water electrolysis system according to claim 1 further includes: Following the step of manufacturing the initial membrane-electrode assembly, the step of connecting an alkaline aqueous solution circulation device to the oxidation electrode of the initial membrane-electrode assembly is described. The alkaline aqueous solution is supplied from the alkaline aqueous solution circulation device to the oxidation electrode of the initial membrane-electrode assembly.

5. The method for preparing the anion exchange membrane water electrolysis system according to claim 1 further includes: After manufacturing the initial membrane-electrode assembly, the step of connecting an alkaline aqueous solution circulation device for the initial reduction electrode and an alkaline circulation device for the oxidation electrode to the initial reduction electrode and oxidation electrode of the initial membrane-electrode assembly, respectively. The alkaline aqueous solution is supplied to the initial reduction electrode and the oxidation electrode of the initial membrane-electrode assembly from an alkaline aqueous solution circulation device for the initial reduction electrode and an alkaline circulation device for the oxidation electrode, respectively.

6. The method for preparing the anion exchange membrane water electrolysis system according to claim 1 further includes: After manufacturing the initial membrane-electrode assembly, the step of installing an alkaline circulation device to connect to both the initial reduction electrode and the oxidation electrode of the initial membrane-electrode assembly is as follows: The alkaline aqueous solution is supplied from the alkaline circulation device to the initial reduction electrode and oxidation electrode of the initial membrane-electrode assembly.

7. The method for preparing the anion exchange membrane water electrolysis system according to claim 1, wherein, The alkaline aqueous solution is a potassium hydroxide aqueous solution with a concentration of 0.1M to 1M.

8. The method for preparing the anion exchange membrane water electrolysis system according to claim 1, wherein, The NiMo-based alloy particles have a molar ratio of Ni to Mo of 3:1, and the Mo oxidation number is 4+, 5+, or 6+.

9. The method for preparing the anion exchange membrane water electrolysis system according to claim 1, wherein, The NiMo-based alloy particles are prepared by a method comprising the following steps: co-precipitating Ni and Mo precursors under alkaline conditions, and then heat-treating the resulting product.

10. The method for preparing the anion exchange membrane water electrolysis system according to claim 1, wherein, The initial reduction electrode is manufactured by a manufacturing method comprising the following steps: applying a slurry for forming the initial reduction electrode onto a release film, the slurry comprising the NiMo-based alloy particles, a binder, and a solvent; drying the slurry; and then separating the dried slurry from the release film.

11. The method for preparing the anion exchange membrane water electrolysis system according to claim 10, wherein, The adhesive is one or more selected from the group consisting of polytetrafluoroethylene, perfluorosulfonic acid, anion exchange resin and cation exchange resin.

12. The method for preparing the anion exchange membrane water electrolysis system according to claim 1, wherein, As a result of the activation, a reduction electrode is produced, wherein The reduction electrode comprises a NiMo-based alloy catalyst, wherein the molar ratio of Ni to Mo is 6:1 to 101:1, and the oxidation number of Mo is 5+ or 6+.

13. The method for preparing the anion exchange membrane water electrolysis system according to claim 12, wherein, The NiMo-based alloy catalyst comprises a Ni layer on its surface.

14. The method for preparing the anion exchange membrane water electrolysis system according to claim 1, wherein, The oxidation electrode is manufactured by a method comprising the following steps: applying a slurry for forming the oxidation electrode onto a release film, the slurry comprising an oxidation catalyst, a binder, and a solvent; drying the slurry; and then separating the dried slurry from the release film, or It is manufactured by a manufacturing method that includes steps of coating, plating or depositing an oxidation catalyst on an electrode substrate.

15. The method for preparing the anion exchange membrane water electrolysis system according to claim 14, wherein, The oxidation catalyst comprises one or more selected from the group consisting of Ni, NiCoFe, Ir, and NiFe layered double hydroxides.

16. The method for preparing the anion exchange membrane water electrolysis system according to claim 1, further comprising: Following activation, a step of testing battery performance is performed by measuring the current density for each range by holding the voltage at 1.45V to 1.9V for 10 seconds in increments of 0.05V.

17. The anion exchange membrane water electrolysis system prepared by the preparation method according to claim 1, wherein the anion exchange membrane water electrolysis system comprises: Reduction electrodes including particulate NiMo-based alloy catalysts; Oxidation electrode; an anion exchange membrane located between the reduction electrode and the oxidation electrode; and alkaline aqueous solutions, The NiMo-based alloy catalyst comprises Ni and Mo in a molar ratio of 6:1 to 101:1, and the oxidation number of Mo is 5+ or 6+.

18. The anion exchange membrane water electrolysis system according to claim 17, further comprising: An anode-supply type alkaline aqueous solution circulation device is connected to the oxidation electrode and supplies the alkaline aqueous solution to the oxidation electrode; a shared-supply type alkaline aqueous solution circulation device is connected to both the oxidation electrode and the reduction electrode and supplies the alkaline aqueous solution to both the oxidation electrode and the reduction electrode; or, a dual-supply type alkaline aqueous solution circulation device for the oxidation electrode, comprising an alkaline aqueous solution circulation device for the oxidation electrode and an alkaline aqueous solution circulation device for the reduction electrode, wherein the alkaline aqueous solution circulation device for the oxidation electrode and the alkaline aqueous solution circulation device for the reduction electrode are each connected to the oxidation electrode and the reduction electrode, respectively.

19. A method for activating anion exchange membrane water electrolysis system, the method comprising the following steps: An initial reduction electrode is activated by supplying an alkaline aqueous solution to an initial anion exchange membrane water electrolysis system, the initial anion exchange membrane water electrolysis system comprising the initial reduction electrode, an oxidation electrode, and an anion exchange membrane between the initial reduction electrode and the oxidation electrode, wherein the initial reduction electrode comprises NiMo-based alloy particles, in which the molar ratio of Ni to Mo is 1:1 to 6:1, and the oxidation number of Mo is 4+, 5+, or 6+. The activation is performed by supplying an alkaline aqueous solution to an initial anion exchange membrane water electrolysis system at 25 mA / cm². 2 Up to 200mA / cm 2 The current density is applied and the current is maintained at 50°C to 60°C for 90 minutes to 360 minutes.

20. The method for activating anion exchange membrane water electrolysis system according to claim 19, wherein, As a result of the activation, a reduction electrode is produced, wherein... The reduction electrode comprises a NiMo-based alloy catalyst, wherein the molar ratio of Ni to Mo is 6:1 to 101:1, and the oxidation number of Mo is 5+ or 6+.

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