Anion-exchange membrane water electrolysis system incorporating reference electrode, and method for producing same

Abstract

One embodiment of the present invention provides an anion-exchange membrane water electrolysis system incorporating a reference electrode, and a method for producing same. The anion-exchange membrane water electrolysis system incorporating a reference electrode according to one embodiment of the present invention places the reference electrode not between reduction (cathode) and oxidation (anode) electrodes but outside of a membrane electrode assembly, thereby allowing overvoltage of each electrode to be measured without degrading system performance.

Description

Anion exchange membrane electrolysis system with reference electrode and method for manufacturing the same

[0001] The present invention relates to an anion exchange membrane electrolysis system with a reference electrode and a method for manufacturing the same.

[0002] Water electrolysis technology is a next-generation, eco-friendly technology that produces hydrogen by electrolyzing water. Among these, the anion exchange membrane water electrolyzer (AEMWE) system is attracting attention as it combines the advantages of alkaline water electrolyzer (AWE)—the ability to use inexpensive, non-precious metal catalysts—with the high system efficiency inherent in the membrane electrode assembly (MEA) design of proton exchange membrane water electrolyzer (PEMWE).

[0003] Accordingly, research is being conducted to develop oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalysts applicable to anion exchange membrane electrolysis under basic conditions. In particular, because electrolysis catalysts are significantly affected by actual reaction conditions, evaluating catalyst performance requires analysis at the membrane electrode assembly level for anion exchange membrane electrolysis.

[0004] Conventional electrochemical water electrolysis systems, including anion exchange membrane electrolysis, are two-electrode systems, consisting of a cathode, which serves as a counter electrode, and an anode, which serves as a working electrode. However, these traditional electrolysis systems can only measure the difference in voltage applied to the two electrodes, making it impossible to isolate the overpotential at each electrode.

[0005] This is due to the absence of a reference electrode, and a non-polarizable electrode that can provide a reference point is required to measure the potential applied to the catalyst material on the electrode surface.

[0006] In the current anion exchange membrane electrolysis process, which lacks a reference electrode, the potentials of the reduction and oxidation electrodes cannot be directly measured. Therefore, only the integrated performance of the electrode assembly can be evaluated, and the catalytic reactivity and stability of the electrochemical catalytic reaction occurring in the catalyst materials of each electrode cannot be directly and separately measured.

[0007] Therefore, in developing and evaluating electrode catalysts with excellent activity and durability in the environment of anion exchange membrane electrolysis, it is important to include a reference electrode to separate and evaluate the overvoltage at each electrode.

[0008] Due to the structural characteristics of membrane electrode assemblies, the oxidation and reduction electrodes are separated only by a thin, solid polymer membrane, an anion exchange membrane. Therefore, it is difficult to include a reference electrode between the electrodes. Conventional methods for including a reference electrode include using a platinum pseudo-reference electrode between the two exchange membranes. However, these methods suffer from instability and can degrade the performance of the water electrolysis system.

[0009] Therefore, many challenges still remain for the development of an anion exchange membrane electrolysis system with a reference electrode capable of directly measuring the potentials of the oxidation and reduction electrodes.

[0010]

[0011] <Prior Art Literature>

[0012] (Patent Document 1) Republic of Korea Patent No. 10-1724060

[0013]

[0014] In order to solve the above-described problems, the technical task of the present invention is to provide an anion exchange membrane electrolysis system with a reference electrode that enables the measurement of the potential of each electrode, which is impossible in existing anion exchange membrane electrolysis systems, and thereby enables the analysis of electrode catalyst performance stably without performance degradation.

[0015] The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0016] In order to achieve the above technical task, one embodiment of the present invention provides an anion exchange membrane electrolysis system in which a reference electrode is introduced.

[0017] According to one embodiment of the present invention, the anion exchange membrane electrolysis system with the reference electrode may include: an electrolysis stack including a membrane electrode assembly comprising an oxidation electrode, a reduction electrode, and an anion exchange membrane having an extension portion extending outward; a reference electrode chamber portion mounted on a side surface of the electrolysis stack, wherein the extension portion of the anion exchange membrane and the reference electrode are connected, and an electric field generated in the electrolysis stack is detected by the reference electrode; and a control portion for controlling the operation of the electrolysis stack and the reference electrode chamber portion and measuring the potential of each of the oxidation electrode and the reduction electrode.

[0018] In addition, according to one embodiment of the present invention, the membrane electrode assembly of the electrolysis stack may be composed of an anion exchange membrane including an oxidation electrode having a catalyst applied to a surface thereof; a reduction electrode positioned opposite the oxidation electrode and having a catalyst applied to a surface thereof; and an extension portion positioned between the oxidation electrode and the reduction electrode and extending outward.

[0019] In addition, according to one embodiment of the present invention, in the membrane electrode assembly of the electrolysis stack, the membrane electrode assembly may further include an extension portion positioned above and below the anion exchange membrane and extending outward, and a plurality of gaskets in the extension portion having a size larger than that of the extension portion of the anion exchange membrane.

[0020] Additionally, according to one embodiment of the present invention, the plurality of gaskets can prevent movement of the anion exchange membrane during the electrolysis process.

[0021] In addition, according to one embodiment of the present invention, in the plurality of gaskets, the anion exchange membrane may be placed in the middle and the intermediate gasket may include a first intermediate gasket in contact with the upper surface and a second intermediate gasket in contact with the lower surface of the anion exchange membrane; an upper gasket positioned above the first intermediate gasket; and a lower gasket positioned below the second intermediate gasket.

[0022] Additionally, according to one embodiment of the present invention, the thickness of the entire plurality of gaskets may be 300 μm to 1000 μm.

[0023] Additionally, according to one embodiment of the present invention, in the anion exchange membrane including the outwardly extending extension portion, the length of the extension portion may be 50 mm to 55 mm.

[0024] In addition, according to one embodiment of the present invention, the reference electrode chamber part may include a lower support part on which the extension part of the anion exchange membrane is installed; a body part positioned on the lower support part and formed of a hollow pillar so that the reference electrode penetrates the inside thereof, fixing the extension part of the anion exchange membrane and having a basic electrolyte injected therein; and an upper fixing part positioned on the body part and formed of a hollow pillar so that the reference electrode penetrates the inside thereof and fixing the reference electrode.

[0025] In addition, according to one embodiment of the present invention, the anion exchange membrane installed in the lower support portion of the reference electrode chamber portion is characterized in that it is continuously wetted by the basic electrolyte stored in the body portion.

[0026] Additionally, according to one embodiment of the present invention, the basic electrolyte injected into the body portion may be composed of potassium hydroxide (KOH) or sodium hydroxide (NaOH).

[0027] In addition, according to one embodiment of the present invention, the lower surface of the reference electrode penetrating the upper fixed portion of the reference electrode chamber portion and the hollow portion of the body portion can be in contact with the anion exchange membrane installed in the lower support portion.

[0028] Additionally, according to one embodiment of the present invention, the upper part of the reference electrode in contact with the anion exchange membrane can be connected to a potentiostat (control unit).

[0029]

[0030] In order to achieve the above technical task, another embodiment of the present invention provides a method for operating an anion exchange membrane electrolysis system in which a reference electrode is introduced.

[0031] A method for operating an anion exchange membrane electrolysis system having a reference electrode according to an embodiment of the present invention may include the steps of: using the anion exchange membrane electrolysis system having the above-described reference electrode, applying a current to an electrolysis stack of the electrolysis system to perform a electrolysis process; driving a liquid pump so that an electrolyte contained in a body of the reference electrode chamber is injected into an extension of the anion exchange membrane; and applying a current in a chronopotentiometry manner from a control unit so that an electric field is detected by a reference electrode of the reference electrode chamber, thereby measuring the voltages of each of an oxidation electrode and a reduction electrode of the electrolysis stack.

[0032] In addition, according to one embodiment of the present invention, by performing a method for operating an anion exchange membrane electrolysis system in which the reference electrode is introduced, the electrical properties of a catalyst formed on the surface of an oxidation electrode and a catalyst formed on the surface of a reduction electrode can be measured.

[0033] An anion exchange membrane electrolysis system with a reference electrode according to one embodiment of the present invention can measure the overvoltage of each electrode without deterioration of system performance by placing the reference electrode outside the membrane electrode assembly rather than between the reduction electrode (cathode) and the oxidation electrode (anode).

[0034] In addition, an extended anion exchange membrane was used to enable the electric field between the electrodes to be detected by an external reference electrode, thereby enabling the device of the present invention to be operated stably and effectively measure the overvoltage of each electrode.

[0035] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the detailed description of the present invention or the composition of the invention described in the claims.

[0036] Figure 1 is a cross-sectional view illustrating an anion exchange membrane electrolysis system in which a reference electrode is introduced according to the present invention.

[0037] Figure 2 is a plan view (a), a side view (b), and a front view (c) illustrating an anion exchange membrane electrolysis system in which a reference electrode is introduced according to the present invention.

[0038] Figure 3 is a cross-sectional view showing the lower support part of the reference electrode chamber.

[0039] Figure 4 is a plan view (a), a side view (b), and a front view (c) showing the lower support part of the reference electrode chamber.

[0040] Figure 5 is a cross-sectional view showing the body of the reference electrode chamber.

[0041] Figure 6 is a plan view (a), a side view (b), and a front view (c) showing the body of the reference electrode chamber.

[0042] Figure 7 is a cross-sectional view showing the upper fixing part of the reference electrode chamber.

[0043] Figure 8 is a plan view (a), a side view (b), and a front view (c) showing the upper fixing part of the reference electrode chamber.

[0044] Figure 9 is a schematic diagram showing an anion exchange membrane having an extension portion extending outward.

[0045] Figure 10 is a schematic diagram showing (a) an upper gasket, (b) a middle gasket, and (c) a lower gasket.

[0046] Figure 11 is an example diagram showing (a) an upper gasket, (b) a middle gasket, and (c) a lower gasket installed with an anion exchange membrane in the center.

[0047] Figure 12 is a flowchart showing a method for operating an anion exchange membrane electrolysis system in which a reference electrode is introduced.

[0048] Figure 13 is a graph of the voltage curves of the oxidation electrode, reduction electrode, and entire cell according to the applied current density.

[0049] Figure 14 is a graph showing the measurement of the oxidation electrode, reduction electrode, and entire cell ohmic resistance.

[0050] Figure 15 is a graph showing the measurement of pseudocapacitance of a reduction electrode coated with Pt / C.

[0051] Figure 16 is a graph showing the pseudocapacitance measurement of an oxidation electrode coated with nickel-iron hydroxide.

[0052] Figure 17 is a graph showing changes in overvoltage measured when a high current density is applied for a long period of time (50 h).

[0053] Figure 18 is an actual photograph showing a configuration in which (a) an extended membrane electrode assembly of the present invention is formed and (b) a configuration in which a bottom of a mounted reference electrode chamber is used.

[0054] Figure 19 is an actual photograph showing (a) a configuration using a mounted reference electrode chamber in the middle and (b) an anion exchange membrane electrolysis system including a conventional electrode.

[0055]

[0056] Hereinafter, the present invention will be described with reference to the attached drawings. However, the present invention can be implemented in various different forms and is therefore not limited to the embodiments described herein. In the drawings, irrelevant parts have been omitted for clarity of description, and similar parts have been designated with similar reference numerals throughout the specification.

[0057] Throughout the specification, when a part is said to be "connected (connected, contacted, or coupled)" to another part, this includes not only cases where it is "directly connected," but also cases where it is "indirectly connected" with another member in between. Furthermore, when a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0058] The terminology used herein is merely used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, it should be understood that the terms "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0059]

[0060] Below, the present invention will be described with reference to the drawings presented in this specification. Note that the drawings may be exaggerated to illustrate the features of the present invention. In such cases, it is preferable to interpret them in light of the overall intent of this specification.

[0061]

[0062] Referring to FIGS. 1 to 11, an anion exchange membrane electrolysis system in which a reference electrode is introduced according to an embodiment of the present invention is described.

[0063] Referring to Figure 1, an anion exchange membrane electrolysis system in which a reference electrode is introduced according to one embodiment of the present invention,

[0064] A water electrolysis stack (100) including a membrane electrode assembly comprising an anion exchange membrane having an oxidation electrode, a reduction electrode, and an extension portion extending outward; a reference electrode chamber portion (200) mounted on a side of the water electrolysis stack, wherein the extension portion of the anion exchange membrane and a reference electrode are connected, and an electric field generated in the water electrolysis stack is detected by the reference electrode; and a control portion for controlling the operation of the water electrolysis stack and the reference electrode chamber portion and measuring the potential of each of the oxidation electrode and the reduction electrode.

[0065] First, the membrane electrode assembly (100) of the electrolysis stack of the present invention may be composed of an oxidation electrode having a catalyst applied to the surface; a reduction electrode positioned opposite the oxidation electrode and having a catalyst applied to the surface; and an anion exchange membrane positioned between the oxidation electrode and the reduction electrode and including an extension portion extending outward.

[0066] At this time, in the electrolysis stack of the present invention, the oxidation electrode can perform a reaction in which an oxidation reaction of water occurs and oxygen and electrons are generated.

[0067] At this time, in order to increase the efficiency of the oxidation reaction of the water, an oxygen generation reaction catalyst may be applied to the oxidation electrode. The catalyst used in the present invention uses a porous nickel diffusion layer on which a certain amount of nickel-iron hydroxide is applied, but is not limited to the above-described example.

[0068] In addition, in the electrolysis stack of the present invention, the reduction electrode can receive electrons generated from the oxidation electrode and perform a reduction reaction to generate hydrogen.

[0069] At this time, in order to increase the efficiency of the reduction reaction, a carbon-based diffusion layer is used on the reduction electrode, in which a certain amount of platinum (Pt / C) supported on a specific surface area carbon, which is a hydrogen generation reaction catalyst, is applied, but is not limited to the above-described example.

[0070]

[0071] *At this time, a reference electrode that enables potential measurement of each electrode, which is impossible in a conventional anion exchange membrane electrolysis system, is introduced into the electrolysis system, thereby introducing a reference electrode that enables stable analysis of electrode catalyst performance without performance degradation. In the present invention, an extended anion exchange membrane is used so that an external reference electrode can detect an electric field between electrodes.

[0072] Referring to FIG. 9, the anion exchange membrane selectively allows anions to pass through and can physically separate the anode and cathode.

[0073] At this time, the main body (12) of the anion exchange membrane extended to the outside of the anion exchange membrane can be installed in the electrolysis stack and physically separate the anode and cathode, and the extension (11) extended to the outside of the anion exchange membrane can be installed in the reference electrode chamber and mounted on the lower part of the reference electrode chamber.

[0074] At this time, in the anion exchange membrane including an extension portion extended outward, the length of the extension portion may be about 50 mm to 55 mm, but the length of the extension portion is not limited to the above-described example and may be changed depending on the size of the electrolysis stack and the reference electrode chamber portion.

[0075] At this time, the size of the area installed in the square-shaped electrolysis stack of the anion exchange membrane must be equal to or larger than the size of the electrode of the electrolysis stack, and the length of the extended portion, which is the extended portion, is characterized by being a distance that is enough to touch the reference electrode located in the reference electrode chamber outside the membrane electrode assembly.

[0076] At this time, the present invention can use materials such as PiperION® Anion Exchange Membrane, Sustainion® Anion Exchange Membrane, etc. as the material of the anion exchange membrane, and although the PiperION Anion Exchange Membrane material is used in the present invention, it is not limited to the above-described examples, and any material of anion exchange membrane actively used in the art can be used without limitation.

[0077] At this time, the thickness of the anion exchange membrane may be 20 μm to 60 μm, and if the thickness of the anion exchange membrane is less than 20 μm, there may be a problem that the anion exchange membrane is not stable when pressure is applied during installation of the water electrolysis stack, and if it exceeds 60 μm, the contact distance of each electrode becomes far, so that the ohmic resistance increases, which may cause a decrease in performance.

[0078] At this time, the present invention may further include an extension portion positioned at the upper and lower portions of the anion exchange membrane and extending outward, and a plurality of gaskets in the extension portion that are larger than the size of the extension portion of the anion exchange membrane.

[0079] At this time, referring to FIGS. 10 and 11, among the plurality of gaskets, the gasket may include a first intermediate gasket in contact with the upper surface of the anion exchange membrane in the center and a second intermediate gasket in contact with the lower surface of the anion exchange membrane; an upper gasket (23) positioned above the first intermediate gasket; and a lower gasket (21) positioned below the second intermediate gasket.

[0080] At this time, the plurality of gaskets can prevent the movement of the anion exchange membrane during the electrolysis process, thereby preventing the anion exchange membrane from shaking.

[0081] At this time, the thickness of the entire plurality of gaskets may be 300 μm to 1000 μm.

[0082]

[0083] *At this time, the reason why the thickness of the entire plurality of gaskets is 300 μm to 1000 μm is because it is a condition in which potassium hydroxide does not leak.

[0084] At this time, the gasket, like the anion exchange membrane, may be installed in the reference electrode chamber portion of the extension portion extending outward from the electrolysis stack, and the main body of the gasket may be installed in the electrolysis stack.

[0085]

[0086] Additionally, the present invention may include a reference electrode chamber portion (200).

[0087] At this time, the reference electrode chamber part (200) is mounted on the side of the electrolysis stack, and the extension of the anion exchange membrane and the reference electrode are connected, so that the electric field generated in the electrolysis stack can be detected by the reference electrode.

[0088] At this time, an extended anion exchange membrane may be installed below the reference electrode so that the external reference electrode can detect the electric field between the electrodes, and the voltage at each of the oxidation electrode and the reduction electrode can be measured by the electric field generated in the electrolysis stack by the reference electrode.

[0089] At this time, the reference electrode chamber part may include a lower support part (201) on which the extension part of the anion exchange membrane is installed; a body part (202) positioned on the lower support part and formed of a hollow pillar so that the reference electrode penetrates the inside thereof, fixing the extension part of the anion exchange membrane and having a basic electrolyte injected therein; and an upper fixing part (203) positioned on the body part and formed of a hollow pillar so that the reference electrode penetrates the inside thereof and fixing the reference electrode.

[0090] At this time, the anion exchange membrane installed on the lower support (201) of the reference electrode chamber is characterized by being continuously wetted by the basic electrolyte stored in the body.

[0091] At this time, 1M concentration potassium hydroxide (KOH), which is a basic electrolyte, was flowed at 1 to 10 mL / min using a liquid pump (SIMDOS 02, KNF) so that the anion exchange membrane installed on the lower support (201) of the reference electrode chamber part was continuously wetted by the basic electrolyte, thereby uniformly wetting the extended anion exchange membrane.

[0092] At this time, the basic electrolyte injected into the body part may be composed of potassium hydroxide (KOH) or sodium hydroxide (NaOH).

[0093] At this time, pressure can be applied between the lower support part and the body part of the chamber to seal it so that the basic electrolyte does not leak.

[0094] At this time, the reason why the anion exchange membrane is continuously wetted by the basic electrolyte is that the anion exchange membrane must be kept wetted by the electrolyte for a long time so that OH- ion exchange can occur smoothly.

[0095] At this time, referring to FIGS. 3 and 4, the lower support member (201) of the present invention may have an anion exchange membrane installed in an area where a groove is dug on the upper surface.

[0096] At this time, a groove is dug into the upper surface of the lower support to prevent the anion exchange membrane from moving.

[0097] In addition, referring to FIGS. 5 and 6, the body part (202) of the present invention is positioned on the lower support part and is formed as a hollow pillar so that a reference electrode penetrates the inside, but an extension of an anion exchange membrane can be fixed and a basic electrolyte can be injected inside.

[0098] At this time, the electrolyte injected into the body part may include a liquid pump that continuously wets the anion exchange membrane with the basic electrolyte.

[0099] At this time, the hollow pillar formed in the body part is intended to allow the reference electrode to penetrate inside, and the diameter of the hollow can be used without limitation as long as the reference electrode can penetrate and maintain a vertical position.

[0100] In addition, referring to FIGS. 7 and 8, the upper fixing part (203) of the present invention is positioned on the body part and is formed as a hollow pillar so that the reference electrode penetrates the inside, and the reference electrode can be fixed therein.

[0101] At this time, the lower surface of the reference electrode penetrating the upper fixed portion of the reference electrode chamber portion and the hollow portion of the body portion can be in contact with the anion exchange membrane installed in the lower support portion.

[0102] At this time, the upper part of the reference electrode in contact with the anion exchange membrane can be connected to the potentiostat (control unit), and in the case of an electrical analysis method for detecting an electric field from the outside, the reference electrode can be used in addition to the potentiostat (control unit).

[0103]

[0104] Therefore, the anion exchange membrane electrolysis system of the present invention, in which the reference electrode is introduced, can measure the overvoltage of each electrode without deterioration of system performance by placing the reference electrode outside the membrane electrode assembly rather than between the reduction electrode (cathode) and the oxidation electrode (anode). In addition, as a method for making this possible, an extended anion exchange membrane is used so that the electric field between the electrodes can be detected by the external reference electrode, and through this, the device of the present invention can be stably operated and has the effect of effectively measuring the overvoltage of each electrode.

[0105]

[0106] A method for operating an anion exchange membrane electrolysis system with a reference electrode according to one embodiment of the present invention is described.

[0107] A method for operating an anion exchange membrane electrolysis system with a reference electrode according to an embodiment of the present invention comprises: using an anion exchange membrane electrolysis system with a reference electrode;

[0108] The method may include a step (S100) of performing a water electrolysis process by applying a current to a water electrolysis stack of the above water electrolysis system; a step (S200) of driving a liquid pump so that an electrolyte included in a body of the reference electrode chamber part is injected into an extension of an anion exchange membrane; and a step (S300) of applying a current in a chronopotentiometry manner in a control part so that an electric field is detected by a reference electrode of the reference electrode chamber part, thereby measuring the voltage of each of an oxidation electrode and a reduction electrode of the water electrolysis stack.

[0109] In the first step, a step of performing a water electrolysis process by applying current to a water electrolysis stack of the water electrolysis system may be included. (S100)

[0110] First, water can be electrolyzed by applying current to the electrolysis stack to generate hydrogen and oxygen gas, and in the present invention, the intensity of the current applied to the electrolysis stack is 0 A cm -2 1.5 A cm -2 It could be.

[0111]

[0112] In the second step, a step of driving a liquid pump so that the electrolyte contained in the body of the reference electrode chamber portion is injected into the extension portion of the anion exchange membrane may be included. (S200)

[0113] The anion exchange membrane installed on the lower support (201) of the above-mentioned reference electrode chamber is characterized by being continuously wetted by the basic electrolyte stored in the body.

[0114] At this time, 1M concentration potassium hydroxide (KOH), which is a basic electrolyte, was flowed at 1 to 10 mL / min using a liquid pump (SIMDOS 02, KNF) so that the anion exchange membrane installed on the lower support (201) of the reference electrode chamber part was continuously wetted by the basic electrolyte, thereby uniformly wetting the extended anion exchange membrane.

[0115] At this time, the basic electrolyte injected into the body part may be composed of potassium hydroxide (KOH) or sodium hydroxide (NaOH).

[0116] At this time, pressure can be applied between the lower support part and the body part of the chamber to seal it so that the basic electrolyte does not leak.

[0117] At this time, the reason why the anion exchange membrane is continuously wetted by the basic electrolyte is that the anion exchange membrane must be kept wetted by the electrolyte for a long time so that OH- ion exchange can occur smoothly.

[0118] In the third step, a step may be included in which a control unit applies a current using a chronopotentiometry method so that an electric field is detected by a reference electrode of the reference electrode chamber section, thereby measuring the voltage of each of the oxidation electrode and reduction electrode of the electrolysis stack. (S300)

[0119] At this time, the step of measuring the voltage of each of the oxidation electrode and reduction electrode of the electrolysis stack in the control unit is the activation step of the catalyst sprayed on the electrode in the electrolysis cell, and is 0.02 Acm -2 After applying a low current, it can be performed by applying a constant current using the chronopotentiometry method.

[0120] At this time, the chronopotentiometry method is one of the electrochemical analysis methods, and is a technique for measuring the change in potential (electrode potential) over time. This method is to apply a constant current to an electrochemical cell and record the electrode potential that changes accordingly over time. The chronopotentiometry method can apply a constant current to the electrochemical cell during the experiment, which does not change throughout the experiment, and by measuring the electrode potential over time while a constant current flows, the characteristics of the electrode reaction can be analyzed.

[0121] At this time, the reference electrode in contact with the anion exchange membrane continuously wetted by the basic electrolyte serves as a reference electrode when measuring the potential (electrode potential), and maintains a constant and known potential compared to other electrodes in the electrolysis system. The reference electrode is used for accurate measurement of potential in electrochemical experiments, provides a constant potential, allows comparison of the potential difference between the working electrode and the auxiliary electrode, and can maintain potential stability for a long time.

[0122] Accordingly, by performing the method for operating an anion exchange membrane electrolysis system in which the reference electrode of the present invention is introduced, the electrical properties of the catalyst formed on the surface of the oxidation electrode and the catalyst formed on the surface of the reduction electrode can be measured.

[0123]

[0124] Hereinafter, the present invention will be described in more detail through manufacturing examples and experimental examples. These manufacturing examples and experimental examples are intended solely to illustrate the present invention, and the scope of the present invention is not limited by these manufacturing examples and experimental examples.

[0125]

[0126] Example: Method for operating an anion exchange membrane electrolysis system with a reference electrode

[0127] First, the membrane electrode assembly of the present invention can be prepared by the same method as a conventional membrane electrode assembly required for conventional anion exchange membrane electrolysis.

[0128] At this time, in the case of the oxidation electrode, a porous nickel diffusion layer (nickel foam) with a certain amount of nickel-iron hydroxide, an oxygen generation reaction catalyst, applied was used.

[0129] At this time, in the case of the reduction electrode, a carbon-based diffusion layer (carbon paper) with a certain amount of platinum (Pt / C) supported on a specific surface area carbon, which is a hydrogen generation reaction catalyst, was used.

[0130] At this time, in the case of the anion exchange membrane, 60μm PiperION, Versogen was used in the present invention.

[0131] At this time, in the case of the single cell of the anion exchange membrane electrolysis system, a product from Fuel Cell Technologies was used.

[0132] Next, the operating method using the above anion exchange membrane electrolysis system is that the extended anion exchange membrane electrolysis system is wetted with a base solution for ion transfer in order for the reference electrode to detect the electric field between the reduction electrode and the oxidation electrode.

[0133] At this time, the present invention is designed to uniformly wet the extended anion exchange membrane by flowing 1M potassium hydroxide (KOH), a basic electrolyte, into the middle of the mounted reference electrode chamber at 20 mL / min using a liquid pump (SIMDOS 02, KNF).

[0134] At this time, pressure was applied between the bottom and middle of the chamber to seal it so that the alkaline electrolyte would not leak out.

[0135] Next, the reference electrode (Hydrogen Reference Electrode HydroFlex, Gaskatel) was fixed to the middle of the liquid-filled reference electrode chamber through the hole at the top of the chamber, immersed in the liquid, and then connected to a potentiostat (VSP-300, Biologic).

[0136] At this time, there are no restrictions on the type or specific product of the reference electrode and potentiostat.

[0137] Next, after connecting to the above potentiostat (VSP-300, Biologic), current was applied using chronopotentiometry to measure the voltage of each oxidation electrode and reduction electrode.

[0138]

[0139] Experimental Example 1: Evaluation of Individual Catalyst Activity in an Anion Exchange Membrane Electrolysis Environment Using an Anion Exchange Membrane Electrolysis with a Reference Electrode

[0140] Referring to FIGS. 13 to 17, the results of evaluating individual catalyst activity in an anion exchange membrane electrolysis environment using an anion exchange membrane electrolysis in which the reference electrode of the present invention is introduced are described.

[0141] Figure 13 is a graph of the voltage curves of the oxidation electrode, reduction electrode, and entire cell according to the applied current density.

[0142] In Fig. 13, in the conventional anion exchange membrane electrolysis, only the voltage difference between the oxidation electrode and the reduction electrode according to the applied current density could be measured, but in the case of the anion exchange membrane electrolysis system of the present invention, the potentials of the oxidation electrode and the reduction electrode according to the applied current density were individually measured.

[0143] Referring to Figure 13, it can be confirmed that the voltages of the oxidation electrode and reduction electrode included in the electrolysis stack were individually measured, and it can be confirmed that this function can be usefully utilized in the development and evaluation of the catalyst used for each electrode.

[0144]

[0145] Figure 14 is a graph showing the measurement of the oxidation electrode, reduction electrode, and entire cell ohmic resistance.

[0146] In Fig. 14, the degree of ohmic resistance contributed to each electrode, which cannot be measured in conventional anion exchange membrane electrolysis, can be analyzed through the present invention.

[0147] Referring to Figure 14, the voltage drop (ohmic drop) at each electrode was corrected to calculate the specific voltage applied to the catalyst.

[0148] The calculation results show that the total cell ohmic resistance is the sum of the ohmic resistances of the oxidation electrode and the reduction electrode, and that the ohmic resistance of the reduction electrode contributes significantly to the total cell.

[0149]

[0150] Figure 15 is a graph showing the measurement of pseudocapacitance of a reduction electrode coated with Pt / C.

[0151] Figure 16 is a graph showing the pseudocapacitance measurement of an oxidation electrode coated with nickel-iron hydroxide.

[0152] In conventional anion exchange membrane electrolysis, since the oxidation electrode and reduction electrode are each polarized, it is impossible to measure pseudocapacitance using cyclic voltammetry in a fixed voltage range. However, in FIGS. 15 and 16, pseudocapacitance was individually measured by introducing a reference electrode through the present invention.

[0153] Referring to FIGS. 16 and 17, the turnover frequency of the catalyst under anion exchange membrane electrolysis conditions can be calculated by deriving the intrinsic state and electrochemically active surface area (ECSA) of the catalyst.

[0154]

[0155] Experimental Example 2: Evaluation of the stability of individual catalysts in an anion exchange membrane electrolysis environment using an anion exchange membrane electrolysis with a reference electrode.

[0156] Figure 17 is a graph showing changes in overvoltage measured when a high current density is applied for a long period of time (50 h).

[0157] Figure 17 shows that the long-term stability of oxidation electrode and reduction electrode catalysts, which is difficult to achieve with existing anion exchange membrane electrolysis systems, was individually evaluated through the present invention.

[0158] Referring to Figure 17, a long-term (50 h) high current density (1 A / cm -2 ) As a result of measuring the overvoltage that changes during application, it was found that the performance degradation of anion exchange membrane electrolysis mainly occurs in the reduction electrode catalyst.

[0159] In addition, as a result of the installation confirmation of the anion exchange membrane electrolysis system with the reference electrode introduced, Fig. 18 is an actual photograph showing the configuration of (a) forming an extended membrane electrode assembly of the present invention and (b) using the bottom of the mounted reference electrode chamber.

[0160] Figure 19 is an actual photograph showing (a) a configuration using a mounted reference electrode chamber in the middle and (b) an anion exchange membrane electrolysis system including a conventional electrode.

[0161] Referring to FIGS. 18 and 19, it can be seen that a reduction electrode stack is installed on the right, a reference electrode chamber is installed on the left, and a wire is connected to the control unit at the top of the reference electrode.

[0162]

[0163] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will readily appreciate that the present invention can be readily modified into other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single entity may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined manner.

[0164] The scope of the present invention is indicated by the claims described below, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

[0165]

[0166] <Explanation of symbols>

[0167] 10: Anion exchange membrane having an extension extending outwardly

[0168] 11: Extension

[0169] 12: Main body

[0170] 20: Gasket

[0171] 21: Bottom gasket

[0172] 22: Stop gasket

[0173] 23: Top gasket

[0174] 100: Electrolysis Stack

[0175] 200: Reference electrode chamber

Claims

1. A water electrolysis stack comprising a membrane electrode assembly comprising an oxidation electrode, a reduction electrode, and an anion exchange membrane having an extension portion extending outwardly; A reference electrode chamber mounted on the side of the electrolysis stack, wherein the extension of the anion exchange membrane and the reference electrode are connected, and the electric field generated in the electrolysis stack is detected by the reference electrode; and An anion exchange membrane electrolysis system with a reference electrode, characterized in that it includes a control unit that controls the operation of the electrolysis stack and the reference electrode chamber and measures the potential of each of the oxidation electrode and the reduction electrode.

2. In paragraph 1, The membrane electrode assembly of the above electrolysis stack is, An oxidation electrode with a catalyst applied to its surface; A reduction electrode positioned opposite to the oxidation electrode and having a catalyst applied to the surface; and An anion exchange membrane electrolysis system characterized in that a reference electrode is introduced, the anion exchange membrane being positioned between the oxidation electrode and the reduction electrode and including an extension portion extending outward.

3. In paragraph 2, In the membrane electrode assembly of the above electrolysis stack, An anion exchange membrane electrolysis system having a reference electrode, characterized in that the anion exchange membrane is positioned at the upper and lower portions thereof and includes an extension portion extending outward, and the extension portion further includes a plurality of gaskets larger than the size of the extension portion of the anion exchange membrane.

4. In paragraph 3, An anion exchange membrane electrolysis system having a reference electrode, characterized in that the above plurality of gaskets prevent movement of the anion exchange membrane during the electrolysis process.

5. In paragraph 3, In the above plurality of gaskets, A stop gasket including a first intermediate gasket in contact with the upper surface of the anion exchange membrane and a second intermediate gasket in contact with the lower surface of the anion exchange membrane; an upper gasket positioned on top of the first intermediate gasket; and An anion exchange membrane electrolysis system having a reference electrode, characterized in that it includes a lower gasket positioned below the second intermediate gasket.

6. In paragraph 1, An anion exchange membrane electrolysis system with a reference electrode, characterized in that the thickness of the entire plurality of gaskets is 300 μm to 1000 μm.

7. In paragraph 1, An anion exchange membrane electrolysis system having a reference electrode, characterized in that the length of the extension portion in the anion exchange membrane including the extension portion extended outward is about 50 mm to 55 mm.

8. In paragraph 1, The above reference electrode chamber part is, A lower support portion on which an extension portion of the anion exchange membrane is installed; A body part positioned on the lower support and formed of a hollow pillar so that a reference electrode penetrates the inside, fixing an extension of an anion exchange membrane and containing a basic electrolyte inside; and An anion exchange membrane electrolysis system with a reference electrode, characterized in that it comprises an upper fixing part that is formed of a hollow pillar positioned on the body part so that the reference electrode penetrates the inside and the reference electrode is fixed thereto.

9. In paragraph 8, An anion exchange membrane electrolysis system with a reference electrode, characterized in that the anion exchange membrane installed on the lower support of the reference electrode chamber is continuously wetted by the basic electrolyte stored in the body.

10. In paragraph 8, An anion exchange membrane electrolysis system with a reference electrode, characterized in that the basic electrolyte injected into the body part is composed of potassium hydroxide (KOH) or sodium hydroxide (NaOH).

11. In paragraph 8, An anion exchange membrane electrolysis system with a reference electrode, characterized in that the lower surface of the reference electrode penetrating the upper fixed portion of the reference electrode chamber portion and the hollow portion of the body portion is in contact with the anion exchange membrane installed in the lower support portion.

12. In paragraph 11, An anion exchange membrane electrolysis system characterized in that the upper part of the reference electrode in contact with the anion exchange membrane is connected to a potentiostat (control unit).

13. In a method for operating an anion exchange membrane electrolysis system using an anion exchange membrane electrolysis system in which the reference electrode of paragraph 1 is introduced, A step of performing a water electrolysis process by applying current to a water electrolysis stack of the above water electrolysis system; A step of driving a liquid pump so that the electrolyte contained in the body of the above-mentioned reference electrode chamber is injected into the extension of the anion exchange membrane; and A method for operating an anion exchange membrane electrolysis system with a reference electrode, characterized in that it includes a step of measuring the voltage of each of the oxidation electrode and reduction electrode of the electrolysis stack by applying a current in a chronopotentiometry manner in a control unit so that an electric field is detected by the reference electrode of the reference electrode chamber unit.

14. In paragraph 13, A method for operating an anion exchange membrane electrolysis system with a reference electrode, characterized in that the method for operating an anion exchange membrane electrolysis system with a reference electrode is performed to measure the electrical properties of a catalyst formed on the surface of an oxidation electrode and a catalyst formed on the surface of a reduction electrode.

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