Alkaline water electrolysis apparatus including metal powder fluid electrodes

Abstract

The present invention discloses a water electrolysis device including a metal powder fluid electrode, which includes a cathode, a first flow channel formed on the cathode, a cation exchange membrane (CEM) formed on the first flow channel, a second flow channel formed on the CEM, and an anode formed on the second flow channel, wherein the second flow channel contains metal powder and is used as a metal powder fluid electrode.

Description

Technical Field

[0001] The present invention relates to an alkaline water electrolysis device including a metal powder fluid electrode. More specifically, the present invention relates to an alkaline water electrolysis device including a metal powder fluid electrode with ultra-low power consumption using a metal oxidation reaction, which can induce an oxidation reaction of metal in a fluidized bed containing metal powder at an anode to metal ions and cause a water decomposition reaction at a cathode to produce hydrogen gas.

Background Art

[0002] In the oxygen evolution reaction (OER) occurring at the anode of solid polymer water electrolysis, four electrons are involved in the reaction, and a high overpotential is applied when a voltage is applied. Due to the overpotential and the strong acidity of the solid polymer electrolyte, the expensive catalysts (iridium / platinum) used cause disadvantages such as high installation costs and weak durability.

[0003] Due to such disadvantages, solid polymer water electrolysis remains at the stage of technological development, and only alkaline water electrolysis is the only commercially available water electrolysis technology. However, even such alkaline water electrolysis is about three times higher than the hydrogen production cost using fossil fuels, and this difference cannot be overcome only by improving the efficiency of the electrolytic cell.

[0004] Commercial water electrolysis has a structure in which hydrogen and oxygen are generated simultaneously. The form of the cell with the distance between both electrodes and the ion exchange membrane minimized for resistance reduction causes mixing of hydrogen and oxygen, and the mixed gas thus generated easily reaches the flammability limit, increasing the risk of explosion. Therefore, in existing water electrolysis technologies, safety issues are always raised, and there are disadvantages that a separation membrane for preventing mixing of hydrogen and oxygen must be included, or an additional process for adjusting the pressures of the hydrogen and oxygen generation channels is required.

[0005] Even in the case of separation-type water electrolysis, which mitigates the risk of oxygen-hydrogen mixed explosions, the oxygen evolution reaction is ultimately not removed during separation, resulting in the generation of oxygen, an explosion hazard, and thus the possibility of explosion cannot be completely eliminated. Furthermore, while separation-type water electrolysis offers cost advantages by removing ion exchange membranes from the process, it adds a step involving an oxidation-reduction mediator, and is a water electrolysis method that does not achieve cost recovery through additional products, despite being a method that offers significant cost advantages. [Overview of the project] [Problems that the invention aims to solve]

[0006] Each embodiment of the present invention provides an ultra-low-power alkaline water electrolysis apparatus that includes a metal powder fluid electrode using a metal oxidation reaction, which can produce hydrogen gas by inducing an oxidation reaction of metal to metal ions in a second flow channel using a metal powder fluid electrode containing metal powder, and by causing a water splitting reaction in a first flow channel, while simultaneously generating zinc hydroxide and / or zinc oxide particle products (e.g., zinc hydroxide and / or zinc oxide nanoparticles).

[0007] Each embodiment of the present invention is not simply limited to improving the performance / energy efficiency of a water electrolysis apparatus, but aims to provide an alkaline water electrolysis apparatus including a metal powder fluid electrode that can gain a cost advantage in line with the growing zinc oxide market through high-value-added zinc oxide synthesized as the process progresses. [Means for solving the problem]

[0008] An alkaline water electrolysis apparatus according to one embodiment of the present invention includes a cathode; a first fluid channel formed on the cathode; a cation exchange membrane (CEM) formed on the first fluid channel; a second fluid channel formed on the cation exchange membrane; and an anode formed on the second fluid channel, wherein the second fluid channel contains metal powder and is used as a metal particle fluidic electrode.

[0009] When a voltage is applied perpendicular to the cation exchange membrane, the metal powder is oxidized in the second fluid channel, generating metal ions, and at the same time, the potential difference of the alkaline water electrolysis apparatus can be adjusted using the standard reduction potential of the metal powder.

[0010] The metal ions generated in the second flow channel may move along the direction of the electric field to the first flow channel.

[0011] In the first flow channel, water is decomposed into hydrogen and hydroxide ions, and the generated hydroxide ions can react with the metal ions to produce at least one of metal hydroxides and metal oxides.

[0012] The alkaline water electrolysis apparatus can adjust the operating temperature and convert the metal hydroxide into the metal oxide within the first fluid channel.

[0013] The operating temperature can be between 20°C and 100°C.

[0014] The aforementioned metal powder may contain, but is not limited to, at least one of zinc (Zn), lead (Pb), cadmium (Cd), iron (Fe), magnesium (Mg), and aluminum (Al).

[0015] The alkaline water electrolysis apparatus may further include a cationic polyelectrolyte layer at the interface between the cathode and the first fluid channel.

[0016] An alkaline water electrolysis apparatus with a zero-gap structure according to an embodiment of the present invention includes a first flow channel; a cathode formed on the first flow channel; a cation exchange membrane formed on the cathode; an anode formed on the cation exchange membrane; and a second flow channel formed on the anode, wherein the second flow channel contains metal powder and is used as a metal powder fluid electrode.

[0017] Another embodiment of the present invention provides an alkaline water electrolysis apparatus comprising: a cathode; a first fluid channel formed on the cathode; an anion exchange membrane (AEM, Anion polyelectrolyte) formed on the first fluid channel; a second fluid channel formed on the anion exchange membrane; and an anode formed on the second fluid channel, wherein the second fluid channel contains metal powder and is used as a metal powder fluid electrode.

[0018] When a voltage is applied perpendicular to the anion exchange membrane, the metal powder is oxidized in the second fluid channel, generating metal ions, and at the same time, the potential difference of the alkaline water electrolysis apparatus can be adjusted using the standard reduction potential of the metal powder.

[0019] In the first flow channel, water is decomposed into hydrogen and hydroxide ions, and the generated hydroxide ions can move along the direction of the electric field to the second flow channel.

[0020] In the second fluid channel, the hydroxide ions can react with the metal ions to produce at least one of metal hydroxides and metal oxides.

[0021] The alkaline water electrolysis device can adjust the driving temperature and convert the metal hydroxide into the metal oxide in the second flow channel.

[0022] The driving temperature can be from 20°C to 100°C.

[0023] The alkaline water electrolysis device can further include an anionic polymer electrolyte layer at the interface between the second flow channel and the anode.

Advantages of the Invention

[0024] Each embodiment of the present invention uses a metal powder particle fluid electrode containing metal powder particles to induce an oxidation reaction of metal to metal ions in a second flow channel and cause a water decomposition reaction in a first flow channel, thereby producing hydrogen gas and simultaneously generating zinc hydroxide or / and zinc oxide particles (for example, zinc hydroxide or / and zinc oxide nanoparticles) products, and can provide an ultra-low power alkaline water electrolysis device including a metal powder particle fluid electrode.

[0025] Each embodiment of the present invention is not limited to simply improving the performance / energy efficiency of the water electrolysis device, and can occupy a cost advantage in line with the zinc oxide market growing through high-value-added zinc oxide synthesized during the process, and can provide an alkaline water electrolysis device including a metal powder particle fluid electrode.

[0026] Furthermore, according to the embodiments of the present invention, an ultra-low power alkaline water electrolysis device using an oxidation reaction of metal powder particles can bring about performance improvement and increased energy efficiency not only in water electrolysis but also when utilized in fuel cells, and thus can cope with the expansion of hydrogen demand.

Brief Description of the Drawings

[0027] [Figure 1] It is a schematic diagram showing an alkaline water electrolysis device according to an embodiment of the present invention. [Figure 2]This is a schematic diagram showing an alkaline water electrolysis apparatus according to one embodiment of the present invention, which includes a cationic polymer electrolyte layer. [Figure 3] This is a schematic diagram showing an alkaline water electrolysis apparatus with a zero-gap structure according to an embodiment of the present invention. [Figure 4] This is a schematic diagram showing an alkaline water electrolysis apparatus according to another embodiment of the present invention. [Figure 5] This is a microscopic image showing an alkaline water electrolysis apparatus according to one embodiment of the present invention. [Figure 6] This graph shows the measurement results of the open-circuit voltage of an alkaline water electrolysis apparatus according to one embodiment of the present invention. [Figure 7] This is a microscopic image of an alkaline water electrolysis apparatus according to one embodiment of the present invention, which includes a cationic polymer electrolyte layer. [Figure 8] This graph shows the measurement results of the open-circuit voltage of an alkaline water electrolysis apparatus according to one embodiment of the present invention, which includes a cationic polymer electrolyte layer. [Figure 9] This is a microscopic image showing the first flow channel containing the cationic polymer electrolyte layer in an alkaline water electrolysis apparatus according to one embodiment of the present invention, which includes a cationic polymer electrolyte layer. [Figure 10] This is a microscopic image showing an alkaline water electrolysis apparatus with a zero-gap structure according to an embodiment of the present invention. [Modes for carrying out the invention]

[0028] The embodiments of the present invention will be described in detail below with reference to the attached drawings and the contents described in those drawings, but the present invention is not limited or restricted by the embodiments.

[0029] The terms used herein are for illustrative purposes only and are not intended to limit the invention. In this specification, singular terms include plural terms unless otherwise specified in the text. As used in this specification, “comprises” and / or “comprising” refer to the presence of components, steps, operations and / or elements and do not exclude the presence or addition of one or more other components, steps, operations and / or elements.

[0030] The terms "examples," "examples," "aspects," and "exemplary" used herein should not be construed as implying that any aspect or design described is better or superior to any other aspect or design.

[0031] Furthermore, the term "or" here refers to inclusive or rather exclusive or. In other words, unless otherwise specified or made clear from the context, the expression "x uses a or b" means one of the natural inclusive permutations.

[0032] Furthermore, any singular expression ("a" or "an") used in this specification and each claim should generally be interpreted as meaning "one or more" unless otherwise specified or unless it is clear from the context that it refers to a singular form.

[0033] The terms used in the following explanation have been selected as common and universal in the relevant technical field; however, other terms may be used due to technological development and / or change, convention, or engineer's preference. Therefore, the terms used in the following explanation should not be understood as limiting the technical ideas, but rather as illustrative terms used to describe the embodiments.

[0034] Furthermore, in certain cases, the applicant may have arbitrarily selected terms, in which case their detailed meaning will be described in the relevant explanatory section. Therefore, the terms used in the following explanations should not be understood simply as names of terms, but rather based on their meaning and the overall content of the specification.

[0035] On the other hand, terms such as "first," "second," etc., can be used to describe various components, but each component is not limited by each term. Each term is used solely for the purpose of distinguishing one component from others.

[0036] Furthermore, when we consider a part such as a membrane, layer, region, or component to be "on top of" another part, this includes not only cases where it is directly above the other part, but also cases where another membrane, layer, region, or component is interposed between them.

[0037] Unless otherwise defined, all terms used herein (including technical and scientific terms) are to be used in a sense that can be commonly understood by a person of ordinary skill in the art to which the present invention pertains. Furthermore, each commonly used predefined term should not be interpreted ideally or excessively unless explicitly defined otherwise.

[0038] On the other hand, when describing the present invention, if it is determined that a specific explanation of a related known function or configuration may obscure the gist of the invention, such detailed explanation will be omitted. Furthermore, the terms used herein are those used to appropriately represent embodiments of the present invention, and these may change depending on the intent of the user and operator or the conventions of the art to which the invention belongs. Therefore, these terms must be defined based on the content throughout this specification.

[0039] Figure 1 is a schematic diagram showing an alkaline water electrolysis apparatus according to one embodiment of the present invention, and Figure 2 is a schematic diagram showing an alkaline water electrolysis apparatus according to one embodiment of the present invention that includes a cationic polymer electrolyte layer.

[0040] An alkaline water electrolysis apparatus according to one embodiment of the present invention includes a cathode 110, a first flow channel 120 formed on the cathode 110, a cation exchange membrane (CEM) 130 formed on the first flow channel 120, a second flow channel 140 formed on the cation exchange membrane 130, and an anode 150 formed on the second flow channel 140.

[0041] An alkaline water electrolysis apparatus according to one embodiment of the present invention is an ultra-low power cation exchange membrane alkaline water electrolysis apparatus that uses the oxidation reaction of metal powders and granules in order to overcome the limitations of existing technologies. It is an electrolysis technology that produces hydrogen gas by inducing an oxidation reaction of metal powders and granules to metal ions in the second flow channel 140 on the anode 150 side and causing a water splitting reaction in the first flow channel 120 on the cathode 110 side.

[0042] In this case, the standard reduction potential of the spontaneously oxidized metal powders can reduce the driving voltage of the alkaline water electrolysis apparatus used in practice. Therefore, an alkaline water electrolysis apparatus using the oxidation reaction of metal powders can produce hydrogen with far less power than existing methods, while simultaneously creating additional value by producing high-value-added metal oxides (e.g., zinc oxide) that can be used in a variety of industries.

[0043] Furthermore, the alkaline water electrolysis apparatus according to one embodiment of the present invention can further improve safety by replacing the oxygen evolution reaction, which requires an expensive catalyst and causes the problem of hydrogen-oxygen mixed explosion, with a metal oxidation reaction.

[0044] The following sections will provide a more detailed explanation of each component.

[0045] First, an alkaline water electrolysis apparatus according to one embodiment of the present invention includes a cathode 110.

[0046] The cathode 110 may include at least one of the following: gold (Au), silver (Ag), platinum (Pt), iridium (Ir), titanium (Ti), ruthenium (Ru), copper (Cu), a Ti-Ru / Ir mesh coated with a titanium (Ti)-ruthenium (Ru) alloy, a platinum (Pt) mesh, a titanium-ruthenium alloy Ti / Ru, indium tin oxide (ITO), stainless steel, and graphite (carbon or graphite fiber).

[0047] An alkaline water electrolysis apparatus according to one embodiment of the present invention includes a first flow channel 120 formed on a cathode 110.

[0048] The first fluid channel 120 may contain a cathode electrolyte.

[0049] The cathode electrolyte may include at least one of the following: potassium ferricyanide (K3Fe(CN)6), sodium chloride (NaCl), sodium sulfate (Na2SO4), hydrochloric acid (HCl), sodium sulfate (Na2SO4), iron(III) chloride (FeCl3), sodium chloride (NaCl), potassium hydroxide (KOH), ammonium bicarbonate (NH4HCO3), potassium carbonate (K2CO3), sodium hydroxide (NaOH), sodium carbonate (Na2CO3), and ultrapure water.

[0050] The cathode electrolyte can be in the form of a solution.

[0051] An alkaline water electrolysis apparatus according to one embodiment of the present invention includes a cation exchange membrane (CEM) 130 formed on a first flow channel 120.

[0052] The cation exchange membrane 130 is a synthetic resin membrane that selectively allows cations to pass through. The cation exchange membrane 130 is negatively charged, making it difficult for negative ions to pass through due to repulsion, and allowing only cations to pass through.

[0053] Therefore, the alkaline water electrolysis apparatus according to one embodiment of the present invention includes a cation exchange membrane 130, which allows metal ions (cations) contained in the second flow channel 140 to selectively permeate to the first flow channel 120. Thus, in the alkaline water electrolysis apparatus according to one embodiment of the present invention, metal ions (cations) can be used as charge transfer ions.

[0054] The cation exchange membrane 130 may include an organic membrane, and preferably includes at least one of polystyrene, polyimide, polyester, polyether, polyethylene, polytetrafluoroethylene, polymethylammonium chloride, and polyglycidyl methacrylate, but is not limited thereto.

[0055] An alkaline water electrolysis apparatus according to one embodiment of the present invention includes a second flow channel 140 formed on a cation exchange membrane 130.

[0056] The second fluid channel 140 contains metal powder and can be used as a metal powder fluid electrode.

[0057] In an alkaline water electrolysis apparatus according to one embodiment of the present invention, the electrode (at least one of the anode and cathode) is the electrode where the oxidation reaction occurs. When a substance with a redox potential is used as a general solid electrode, a problem may arise in which the electrode is consumed due to the sustained oxidation reaction. Such a consumed electrode (at least one of the anode and cathode) requires replacement, which interferes with continuous water electrolysis.

[0058] However, in one embodiment of the present invention, compared to existing electrodes that do not require electrode replacement, the alkaline water electrolysis apparatus uses a metal powder fluid electrode, which allows the powder to be injected into the fluid channel (at least one of the first and second fluid channels) together with the electrolyte at the same time as the system is driven, and can be consumed by undergoing an oxidation reaction in the fluid channel instead of the electrode.

[0059] Therefore, by replacing the electrode where a redox potential exists with a granular material containing a substance equivalent to an electrode, the phenomenon of electrode (i.e., at least one of the anode and cathode) being consumed can be overcome, and continuous water electrolysis becomes possible.

[0060] Furthermore, the metal powders can be injected into the cell through the flow channels (at least one of the first and second flow channels) while mixing with the electrolyte, and spread uniformly within the flow channels (at least one of the first and second flow channels). Since each metal powder can act as an electrode (at least one of the anode and cathode), the problem of increased maintenance costs due to the wear and replacement of electrodes (at least one of the anode and cathode) can be solved, and the system can contribute to improved efficiency and increased water electrolysis capacity by increasing the effective area on which oxidation reactions occur.

[0061] Furthermore, in order to obtain a power reduction effect by utilizing a battery that uses the oxidation potential of the metal anode 150 for water electrolysis, the alkaline water electrolysis apparatus according to one embodiment of the present invention can continuously supply the anode 150 material using a metal powder fluid electrode.

[0062] Therefore, when a voltage is applied perpendicular to the cation exchange membrane 130, the metal powder is oxidized in the second flow channel 140, generating metal ions, while simultaneously adjusting the potential difference of the alkaline water electrolysis device.

[0063] Specifically, in one embodiment of the present invention, the alkaline water electrolysis apparatus has a structure in which the hydrogen generation channel (first flow channel 120) and the metal powder fluid electrode (second flow channel 140) are separated by an ion-selective cation exchange membrane 130. When the metal powder in the second flow channel 140 on the anode 150 side is oxidized to metal ions, it has a standard reduction potential of -0.76V. This reaction can be used to reduce the potential difference required for electrolysis, thereby obtaining a gain at the cost of hydrogen production.

[0064] Therefore, by replacing the reaction occurring on the anode 150 side with a metal oxidation reaction that is not an oxygen evolution reaction, it is possible to eliminate the need for the expensive catalyst required for the oxygen evolution reaction and to eliminate the risk of a hydrogen-oxygen mixed gas explosion due to oxygen evolution.

[0065] Furthermore, metal ions generated in the second flow channel 140 on the anode 150 side and hydroxide ions generated in the first flow channel 120 on the cathode 110 side move through the cation exchange membrane during the water electrolysis process and are synthesized into at least one of metal hydroxides and metal oxides. This allows for the recovery of a large portion of hydrogen production costs through metal oxides (e.g., zinc oxide), which are high-value-added products that are more expensive than metals (e.g., zinc).

[0066] The potential difference required for electrolysis in an alkaline water electrolysis apparatus according to one embodiment of the present invention can be within -0.36V (lower heating value), and if the potential difference is less than -0.36V, a problem may arise in which water decomposition does not occur.

[0067] The metal powder may contain at least one of zinc (Zn), lead (Pb), cadmium (Cd), iron (Fe), magnesium (Mg), and aluminum (Al), and preferably zinc (Zn). Zinc is a substance that has a high oxidation potential corresponding to +0.76V, and has the advantages of being less expensive and non-flammable compared to other metals.

[0068] For example, in one embodiment of the present invention, an alkaline water electrolysis apparatus uses a cation exchange membrane 130 as a separation membrane and zinc ions as charge transfer ions. This allows zinc ions oxidized in the second fluid channel (e.g., zinc powder fluid channel) on the anode 150 side to move to the cathode 110 side via the cation exchange membrane 130, where they meet hydroxide ions generated through a hydrogen evolution reaction, thereby producing zinc oxide.

[0069] Furthermore, when hydroxide ions are used as charge transfer ions, zinc oxide is generated and surrounds the zinc powder, forming a film that prevents the oxidation reaction of zinc, or it may be necessary to separate the zinc oxide product from the zinc powder. However, in one embodiment of the present invention, by using zinc powder, which is a metal powder, as the charge transfer ions, the zinc oxide generation channel is moved to the cathode 110 side, and the process of preventing the oxidation reaction of zinc by forming a film that surrounds the zinc powder, or separating the zinc oxide product from the zinc powder, can be eliminated.

[0070] Furthermore, in one embodiment of the present invention, the electron transfer capacity of the alkaline water electrolysis apparatus can be adjusted by the concentration of metal powder contained in the second flow channel 140. Specifically, as the concentration of metal powder contained in the second flow channel 140 increases, electrons are effectively transferred from the electrodes to the metal powder, and the target oxidation-reduction reaction efficiency can increase.

[0071] For example, the concentration of metal granules contained in the second flow channel 140 can be between 1 wt% and 20 wt%. If the concentration of metal granules is less than 1 wt%, there is a problem that the metal granules and electrodes may come into discontinuous contact. If the concentration of metal granules is greater than 20 wt%, there is a problem that the metal granules will not flow within the second flow channel 140.

[0072] As demonstrated by the examples, metal powders and granules can be metal nanoparticles.

[0073] Furthermore, the second fluid channel 140 can contain the anodic electrolyte.

[0074] The anodic electrolyte may contain, but is not limited to, at least one of the following: sodium acetate (CH3COONa) + phosphate, phosphate-buffered saline (PBS), ammonium chloride (NH4Cl), monosodium phosphate (NaH2PO4), potassium ferrocyanide (K4Fe(CN)6), sodium sulfate (Na2SO4), ammonium bicarbonate (NH4HCO3), sodium hydroxide (NaOH), sodium chloride (NaCl), iron(II) chloride (FeCl2), sulfuric acid (H2SO4), sodium chloride (NaCl), and potassium hydroxide (KOH).

[0075] The form of the anodic electrolyte can be a solution.

[0076] An alkaline water electrolysis apparatus according to one embodiment of the present invention includes an anode 150 formed on a second flow channel 140.

[0077] Anode 150 may include at least one of the following: gold (Au), silver (Ag), platinum (Pt), iridium (Ir), aluminum (Al), titanium (Ti), ruthenium (Ru), a Ti-Ru / Ir mesh coated with a titanium (Ti)-ruthenium (Ru) alloy, a platinum (Pt) mesh, a titanium-ruthenium alloy Ti / Ru, and indium tin oxide (ITO). Anode 150 may also include at least one of the following: chromium (Cr), nickel (Ni), molybdenum (Mo) used as titanium V4A steel, and chromium (Cr) and iron (Fe) used as stainless steel.

[0078] The water electrolysis mechanism using an alkaline water electrolysis apparatus according to one embodiment of the present invention will be explained as follows: First, when a voltage is applied perpendicular to the cation exchange membrane 130, the metal powder is oxidized in the second flow channel 140, generating metal ions. At the same time, the potential difference of the alkaline water electrolysis apparatus can be adjusted using the standard reduction potential of the metal powder.

[0079] Subsequently, the metal ions generated in the second flow channel 140 may move to the first flow channel 120 along the direction of the electric field. At the same time, in the first flow channel 120, water is decomposed into hydrogen and hydroxide ions, and the resulting hydroxide ions can react with the metal ions to produce at least one of metal hydroxides and metal oxides.

[0080] In this case, the alkaline water electrolysis apparatus according to one embodiment of the present invention can adjust the operating temperature and convert metal hydroxide into metal oxide within the first flow channel 120.

[0081] The operating temperature can be between 20°C and 100°C. If the operating temperature is below 20°C, the Gibbs free energy required for water splitting increases, which leads to a problem of a higher minimum voltage being required. If the operating temperature is above 100°C, the ionic conductivity increases, which may improve water electrolysis performance, but it requires even more thermal energy to raise the temperature. In addition, the water, which is the liquid electrolyte, evaporates within the water electrolysis device, damaging the ion exchange membrane inside the device due to heat and reducing its lifespan.

[0082] For example, when zinc powder is used as the metal powder, the alkaline water electrolysis apparatus according to one embodiment of the present invention is a zinc oxidation reaction-based alkaline water electrolysis apparatus that may be configured to include an anode 150 on which zinc is oxidized, a cathode 110 on which hydrogen is generated, and a cation exchange membrane 130 that physically separates both electrodes and the electrolyte.

[0083] At this time, when a voltage is applied perpendicular to the cation exchange membrane 130, zinc is spontaneously oxidized on the anode 150 side, and the potential difference required for water splitting can be reduced by the standard reduction potential of the reaction. The zinc ions move to the cathode 110 side as they pass through the cation exchange membrane 130, and at the same time, hydrogen is generated when water is decomposed into hydrogen and hydroxide ions on the cathode 110 side. The generated hydroxide ions can then be synthesized into zinc oxide by encountering zinc ions.

[0084] At this time, the reaction of water in the first flow channel 120 is as shown in Equation 1 below, and the reaction of zinc powder in the second flow channel 140 is as shown in Equation 2 below.

[0085] H2O + 2e- → H2↑ + 2OH - (E0 = -0.83V vs. SHE) (Equation 1) Zn → Zn 2+ +2e - (E0=0.76V vs.SHE) (Formula 2)

[0086] Furthermore, by adjusting the temperature within the operating temperature range, the product can be converted from zinc hydroxide to zinc oxide particles (e.g., zinc oxide nanoparticles). The resulting zinc oxide is an advanced material used in the rubber, ceramics, pharmaceutical, and cosmetics industries, and is a high-value-added product that is more expensive than zinc.

[0087] Therefore, in one embodiment of the present invention, by adding the electrode material to the second flow channel 140 and shaping it so that the electrode flows through the second flow channel 140, the voltage required for driving is reduced by the chemical energy released by the oxidation of zinc, and at the same time, zinc ions are transferred via the cation exchange membrane 130, enabling the synthesis of zinc hydroxide / zinc oxide in the cathode electrolyte.

[0088] As demonstrated by the examples, the alkaline water electrolysis apparatus according to one embodiment of the present invention may further include a cationic polymer electrolyte layer 160 at the interface between the cathode 110 and the first flow channel 120.

[0089] Specifically, by adding a cationic polymer electrolyte layer 160 to the hydrogen generation channel on the cathode 110 side, the positively charged (+) cationic polymer electrolyte has the property of moving in the direction of the electric field, so it is pulled towards the cathode 110, and a film made of the polymer electrolyte can be formed on the surface of the cathode 110.

[0090] The formed cationic polymer electrolyte layer 160 is positively charged, so through its electrostatic properties, it repels cations and allows anions to pass through. Through this, zinc ions that have entered the first flow channel 120 on the cathode 110 side while passing through the cation exchange membrane 130 are reduced on the cathode 110, preventing the formation of metallic dendrites. Hydroxide ions generated through the hydrogen evolution reaction are allowed to pass through, thus separating the hydrogen generation portion from the zinc oxide synthesis portion.

[0091] Furthermore, since the polymer electrolyte (preferably an aqueous solution of the polymer electrolyte) exists in the form of charged polymer chains in the aqueous solution, it contains a large amount of water, so there is no problem in supplying the water necessary for the hydrogen generation reaction. Moreover, because it is a charged polymer, it can also increase the conductivity of the electrolyte, that is, it can reduce resistance.

[0092] The cationic polymer electrolyte layer 160 is used as the cathode electrolyte, and the reaction can be controlled by separating the generated hydrogen from the zinc hydroxide / zinc oxide. The cationic polymer electrolyte is positively charged, and when a voltage is applied, it moves towards the cathode side due to the generated electric field and adsorbs to the electrode. In this way, the cationic polymer electrolyte surrounding the cathode 110 can suppress dendritic formation by preventing zinc ions in the first flow channel 120 from moving to the cathode 110.

[0093] The cationic polymer electrolyte layer 160 may further contain at least one of PQ-10, PEI (protonated polyethyleneimine), PAH (protonated poly(allylamine)), and PDADMAC (polydiallyldimethylammonium chloride).

[0094] An ultra-low-power alkaline water electrolysis device using a metal oxidation reaction (e.g., zinc oxidation reaction) according to one embodiment of the present invention can be used not only for water electrolysis but also in fuel cells to improve performance and increase energy efficiency, thus enabling it to meet the growing demand for hydrogen.

[0095] Furthermore, beyond simply improving the performance / energy efficiency of alkaline water electrolysis equipment, it is possible to gain a cost advantage in the growing zinc oxide market through the high-value-added zinc oxide synthesized as the process progresses.

[0096] Figure 3 is a schematic diagram showing an alkaline water electrolysis apparatus with a zero-gap structure according to an embodiment of the present invention.

[0097] An alkaline water electrolysis apparatus with a zero-gap structure according to an embodiment of the present invention includes a first flow channel 120, a cathode 110 formed on the first flow channel 120, a cation exchange membrane 130 formed on the cathode 110, an anode 150 formed on the cation exchange membrane 130, and a second flow channel 140 formed on the anode 150, wherein the second flow channel 140 contains metal powder and is used as a metal powder fluid electrode.

[0098] Liquid electrolytes exert relatively greater resistance to ion transfer compared to solid polymer ion exchange membranes. The longer the liquid electrolyte channel in the ion transfer path, the greater the resistance; conversely, the shorter the liquid electrolyte channel, the less resistance there is. To minimize this resistance, the liquid electrolyte channel is excluded from the ion transfer path, resulting in a zero-gap structure.

[0099] Therefore, the alkaline water electrolysis apparatus with a zero-gap structure according to the embodiment of the present invention has a configuration in which the anode 150 and the cation exchange membrane 130 are attached to each other, thereby excluding the first flow channel 120 and the second flow channel 140, which have high resistance between the anode 150 and the cathode 110 and the cation exchange membrane 130, from the zinc ion transport path, and by being located outside the anode and cathode, the resistance between the anode 150 and the cathode 110 can be minimized.

[0100] As a result, in the zero-gap structure, the resistance acts as a small amount even when the same voltage is applied, allowing a higher current to flow, and increasing the amount of hydrogen generated, which is proportional to the current value. Furthermore, in Figure 1, hydrogen bubbles generated in the liquid electrolyte between the anode 150 and the cathode 110 can act as resistance in the water electrolysis device. However, in the case of Figure 3, hydrogen bubbles are generated outside the zinc ion transfer path from the anode to the cathode, rather than within the zinc ion transfer path. Therefore, the problem of increased electrical resistance due to bubbles during the hydrogen production process can be solved, and similarly, the effect of increasing the amount of hydrogen generated can be obtained.

[0101] Figure 4 is a schematic diagram showing an alkaline water electrolysis apparatus according to another embodiment of the present invention.

[0102] Since an alkaline water electrolysis apparatus according to another embodiment of the present invention may include the same components as the alkaline water electrolysis apparatus according to the embodiment of the present invention, except that hydroxide ions are used as charge transfer ions by using an anion exchange membrane 230, a description of the same components will be omitted.

[0103] Another embodiment of the present invention provides an alkaline water electrolysis apparatus comprising a cathode 210, a first fluid channel 220 formed on the cathode 210, an anion exchange membrane (AEM, Anion polyelectrolyte) 230 formed on the first fluid channel 220, a second fluid channel 240 formed on the anion exchange membrane 230, and an anode 250 formed on the second fluid channel 240, wherein the second fluid channel 240 contains metal powder and is used as a metal powder fluid electrode.

[0104] Another embodiment of the present invention is an alkaline water electrolysis apparatus that includes an anion exchange membrane 230 formed on a first flow channel 220.

[0105] The anion exchange membrane 230 is a synthetic resin membrane that selectively allows anions to pass through. It is positively charged, making it difficult for cations to pass through due to repulsion, and allowing only anions to pass through.

[0106] Therefore, an alkaline water electrolysis apparatus according to another embodiment of the present invention includes an anion exchange membrane 230, which allows hydroxide ions (anions) contained in the first flow channel 220 to selectively permeate to the second flow channel 240. Thus, in an alkaline water electrolysis apparatus according to another embodiment of the present invention, hydroxide ions (anions) can be used as charge transfer ions.

[0107] The anion exchange membrane 230 may contain at least one of the following: Fumatesp FAA3 from Fumatech, A201 from Tokuyama, AEMION from Ionomr, Sustainion from Dioxide Material, Durion TM1 from Orion Polymer, AMHPP from Ralex, and AMHES from Ralex.

[0108] In another embodiment of the present invention, when a voltage is applied perpendicular to the anion exchange membrane 230, the metal powder is oxidized in the second flow channel 240, generating metal ions, while simultaneously adjusting the potential difference of the alkaline water electrolysis apparatus.

[0109] In addition, water is decomposed into hydrogen and hydroxide ions in the first flow channel 220, and the resulting hydroxide ions may move to the second flow channel 240 along the direction of the electric field.

[0110] Therefore, in the second flow channel 240, hydroxide ions can react with metal ions to produce at least one of metal hydroxides and metal oxides.

[0111] In this case, the alkaline water electrolysis apparatus according to another embodiment of the present invention can adjust the operating temperature and convert metal hydroxide to metal oxide in the second flow channel 240.

[0112] The operating temperature can be between 20°C and 100°C. If the operating temperature is below 20°C, the Gibbs free energy required for water splitting increases, which leads to a problem of a higher minimum voltage being required. If the operating temperature is above 100°C, the ionic conductivity increases, which may improve water electrolysis performance, but it also leads to a problem of requiring more thermal energy to raise the temperature. Furthermore, the water, which is the liquid electrolyte, evaporates within the water electrolysis device, damaging the ion exchange membrane inside the device due to heat and reducing its lifespan.

[0113] Unlike the alkaline water electrolysis apparatus according to one embodiment of the present invention, the alkaline water electrolysis apparatus according to another embodiment of the present invention uses hydroxide ions as charge transfer ions. These hydroxide ions have much higher ion mobility than zinc ions, which are charge transfer ions in the alkaline water electrolysis apparatus according to one embodiment of the present invention. As a result, the ion transfer resistance of the first flow channel 220, the second flow channel 240, and the anion exchange membrane 230 is much lower, so the current value that flows when the same voltage is applied can be increased, and the amount of hydrogen generated can be increased.

[0114] As shown in the examples, an alkaline water electrolysis apparatus according to another embodiment of the present invention may further include an anionic polymer electrolyte layer 260 at the interface between the second flow channel 240 and the anode 250.

[0115] In another embodiment of the present invention, when an alkaline water electrolysis apparatus uses an anion exchange membrane 230 and hydroxide ions are used as charge transfer ions, fouling generated at the electrodes can be prevented by forming an anionic polymer electrolyte layer 260 using an anionic polymer electrolyte aqueous solution that moves towards the anode 250 side by an electric field, in order to prevent precipitate formation at the anode 250.

[0116] [Manufacturing Example 1]: Alkaline water electrolysis apparatus according to one embodiment of the present invention (Figure 1) The apparatus consists of an anode (carbon), a second flow channel containing zinc powder (ZnSO4 0.5M), a cation exchange membrane, a first flow channel (NaOH 0.5M), and a cathode (carbon). Electrolytes were injected into both the first and second flow channels at a flow rate of 10 μL / min, and bubble formation was observed when a 2V voltage was applied. In the case of OCV (Open Circuit Voltage), it refers to the voltage measured under 0A current conditions before applying the voltage for the bubble formation experiment; this indicates the degree of voltage gain obtained from the zinc oxidation reaction when the voltage is applied immediately.

[0117] [Manufacturing Example 2]: Alkaline water electrolysis apparatus according to one embodiment of the present invention, including a cationic polymer electrolyte layer (Figure 2) The apparatus consists of an anode (carbon), a second flow channel containing zinc powder (ZnSO4 0.5M), a cation exchange membrane, a first flow channel containing a cationic polymer electrolyte (NaOH 0.5M + cationic polyelectrolyte), and a cathode (carbon). The cationic solid polymer electrolyte used is polyquaternium-10(pq-10) 1 wt%. The electrolyte was injected into both the first and second flow channels at a flow rate of 10 μL / min, and bubble generation was observed when a voltage of 2 V was applied. In the case of OCV (Open Circuit Voltage), it refers to the voltage measured under 0 A current conditions before applying the voltage for the bubble generation experiment, and this indicates the degree of voltage gain obtained from the zinc oxidation reaction when the voltage is applied immediately.

[0118] [Manufacturing Example 3]: Alkaline water electrolysis apparatus with zero-gap structure according to an embodiment of the present invention (Figure 3) It was manufactured in the same manner as in Manufacturing Example 1, except that it comprises a second flow channel; an anode (carbon); a cation exchange membrane; a cathode (carbon); and a first flow channel.

[0119] Figure 5 is a microscopic image showing an alkaline water electrolysis apparatus according to one embodiment of the present invention, and Figure 6 is a graph showing the measurement results of the open-circuit voltage of the alkaline water electrolysis apparatus according to one embodiment of the present invention.

[0120] Referring to Figure 5, it can be seen that when 0.5M NaOH is used in the first flow channel, hydrogen bubbles are generated in the cathode-side channel.

[0121] Furthermore, referring to Figure 6, it can be seen that the alkaline water electrolysis apparatus according to one embodiment of the present invention can obtain a voltage gain of 0.651V during operation.

[0122] Figure 7 is a microscopic image of an alkaline water electrolysis apparatus according to one embodiment of the present invention, which includes a cationic polymer electrolyte layer, and Figure 8 is a graph showing the measurement results of the open-circuit voltage of an alkaline water electrolysis apparatus according to one embodiment of the present invention, which includes a cationic polymer electrolyte layer.

[0123] Referring to Figure 7, it can be seen that when 0.5M NaOH and 1 wt% pq-10, a cationic polymer electrolyte, are used in the first flow channel, hydrogen bubbles are generated in the cathode-side channel.

[0124] Referring to Figure 8, it can be seen that an alkaline water electrolysis apparatus according to one embodiment of the present invention, which includes a cationic polymer electrolyte layer, can obtain a voltage gain of 0.64 V during operation.

[0125] Figure 9 is a microscopic image showing the first flow channel containing the cationic polymer electrolyte layer in an alkaline water electrolysis apparatus according to one embodiment of the present invention, which includes a cationic polymer electrolyte layer.

[0126] Referring to Figure 9, it can be confirmed that in a zinc-zinc symmetric structure apparatus, the cationic polymer electrolyte (pq-10) layer generated on the cathode side prevents zinc ions from moving to the cathode and being reduced, resulting in only the hydrogen evolution reaction occurring.

[0127] Figure 10 is a microscopic image showing an alkaline water electrolysis apparatus with a zero-gap structure according to an embodiment of the present invention.

[0128] Referring to Figure 10, it can be seen that alkaline water electrolysis devices with a zero-gap structure according to embodiments of the present invention are commonly manufactured.

[0129] On the other hand, the embodiments of the present invention disclosed herein and in the drawings are merely examples provided to facilitate understanding and are not intended to limit the scope of the invention. It will be obvious to those ordinary skill in the art to which the present invention pertains that other modifications based on the technical idea of ​​the present invention are also possible, in addition to the embodiments disclosed herein.

Claims

1. cathode; A first flow channel formed on the cathode; A cation exchange membrane (CEM) formed on the first fluid channel; A second fluid channel formed on the cation exchange membrane; and Anode formed on the second flow channel; Includes, The second fluid channel contains metal powder and is used as a metal powder fluid electrode. The alkaline water electrolysis apparatus is characterized in that the metal powder contains zinc (Zn).

2. The alkaline water electrolysis apparatus according to claim 1, characterized in that when a voltage is applied perpendicular to the cation exchange membrane, the metal powder is oxidized in the second fluid channel to generate metal ions, and at the same time, the potential difference of the alkaline water electrolysis apparatus is adjusted using the standard reduction potential of the metal powder.

3. The alkaline water electrolysis apparatus according to claim 2, characterized in that the metal ions generated in the second flow channel move to the first flow channel along the direction of the electric field.

4. The alkaline water electrolysis apparatus according to claim 3, characterized in that water is decomposed into hydrogen and hydroxide ions in the first fluid channel, and the generated hydroxide ions react with the metal ions to produce at least one of metal hydroxide and metal oxide.

5. The alkaline water electrolysis apparatus according to claim 4, characterized in that the alkaline water electrolysis apparatus adjusts the operating temperature and converts the metal hydroxide into the metal oxide in the first fluid channel.

6. The alkaline water electrolysis apparatus according to claim 5, characterized in that the operating temperature is 20°C to 100°C.

7. The alkaline water electrolysis apparatus according to claim 1, further comprising a cationic polymer electrolyte layer at the interface between the cathode and the first fluid channel.

8. First flow channel; Cathode formed on the first flow channel; A cation exchange membrane formed on the cathode; Anode formed on the cation exchange membrane; and, A second flow channel formed on the anode; Includes, The second flow channel contains metal powder and is used as a metal powder fluid electrode. The aforementioned metal powder contains zinc (Zn), and is characterized by being an alkaline water electrolysis apparatus with a zero-gap structure.

9. cathode; A first flow channel formed on the cathode; An anion exchange membrane (AEM, Anion Polyelectrolyte) formed on the first fluid channel; A second fluid channel formed on the anion exchange membrane; and, Anode formed on the second flow channel; Includes, The second fluid channel contains metal powder and is used as a metal powder fluid electrode. The alkaline water electrolysis apparatus is characterized in that the metal powder contains zinc (Zn).

10. The alkaline water electrolysis apparatus according to claim 9, characterized in that when a voltage is applied perpendicular to the anion exchange membrane, the metal powder is oxidized in the second fluid channel to generate metal ions, and at the same time, the potential difference of the alkaline water electrolysis apparatus is adjusted using the standard reduction potential of the metal powder.

11. The alkaline water electrolysis apparatus according to claim 10, characterized in that water is decomposed into hydrogen and hydroxide ions in the first flow channel, and the generated hydroxide ions move to the second flow channel along the direction of the electric field.

12. The alkaline water electrolysis apparatus according to claim 11, characterized in that in the second fluid channel, the hydroxide ions react with the metal ions to produce at least one of metal hydroxides and metal oxides.

13. The alkaline water electrolysis apparatus according to claim 12, characterized in that the alkaline water electrolysis apparatus adjusts the operating temperature and converts the metal hydroxide into the metal oxide in the second fluid channel.

14. The alkaline water electrolysis apparatus according to claim 13, characterized in that the operating temperature is 20°C to 100°C.

15. The alkaline water electrolysis apparatus according to claim 9, further comprising an anionic polymer electrolyte layer at the interface between the second fluid channel and the anode.

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