Electrolysis device and method for operating the electrolysis device

Abstract

To simplify the configuration of an electrolytic apparatus.SOLUTION: An electrolytic apparatus comprises: an electrolysis cell including a cathode, an anode, a cathode flow channel facing the cathode, and an anode flow channel facing the anode; a tank including a first accommodation unit, a second accommodation unit, and an opening for connecting the first accommodation unit to the second accommodation unit, both of which can accommodate a liquid including at least one ion that can be moved from the first accommodation unit to the second accommodation unit through the opening by forming the difference of elevation between the first liquid surface and the second liquid surface so that the height of the first liquid surface of the liquid accommodated in the first accommodation unit to the lower part of the second accommodation unit is higher than the height of the second liquid surface of the liquid accommodated in the second accommodation unit to the lower part of the second accommodation unit; a first flow channel for connecting the outlet of the cathode flow channel to the first accommodation unit; and a second flow channel for connecting the second accommodation unit to the outlet of the anode flow channel.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrolysis device and a method for driving the electrolysis device. [Background technology]

[0002] In recent years, from the viewpoints of both energy and environmental issues, it is desired not only to convert renewable energy such as solar power generation into electrical energy for use, but also to convert it into a state that can be stored and transported. In response to this demand, research and development of artificial photosynthesis technology that produces chemical substances using sunlight, like photosynthesis by plants, is being carried out. This technology is expected to make it possible to store renewable energy as storable fuel, and to create value by producing chemical substances that can be used as industrial raw materials.

[0003] As a device for producing chemical substances using renewable energy such as solar power generation, an electrochemical reaction device is known that has a cathode that reduces carbon dioxide (CO2) generated, for example, from a power plant or a waste treatment plant, and an anode that oxidizes water (H2O). At the cathode, for example, carbon dioxide is reduced to produce carbon compounds such as carbon monoxide (CO). When realizing such an electrochemical reaction device in a cell form (also called an electrolysis cell), it is considered effective to realize it in a form similar to a fuel cell such as a Polymer Electric Fuel Cell (PEFC). By directly supplying carbon dioxide to the catalyst layer of the cathode, it is possible to rapidly proceed with the carbon dioxide reduction reaction.

[0004] However, such cell configurations present a problem similar to that of PEFCs: the resistance of the electrolysis cell needs to be kept low in order to achieve a robust and durable electrolysis cell. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2022-42280 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to simplify the configuration of an electrolysis device. [Means for solving the problem]

[0007] The electrolysis device of the embodiment includes an electrolysis cell including a cathode, an anode, a cathode flow path facing the cathode, and an anode flow path facing the anode; a tank having a first storage unit, a second storage unit, and an opening connecting the first storage unit and the second storage unit, the first storage unit and the second storage unit being capable of storing a liquid including at least one ion, and forming a height difference between the first liquid level and the second liquid level such that the height of the first liquid level of the liquid contained in the first storage unit relative to a lower part of the second storage unit is higher than the height of the second liquid level of the liquid contained in the second storage unit relative to the lower part of the second storage unit, thereby transferring ions contained in the liquid from the first storage unit to the second storage unit through the opening; a first flow path connecting an outlet of the cathode flow path and the first storage unit; and a second flow path connecting the second storage unit and an outlet of the anode flow path. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a configuration example of an electrolysis device 1. [Diagram 2] 2 is a schematic diagram showing an example of the structure of a tank 200. FIG. [Diagram 3] 3 is a schematic diagram showing another example of the structure of the tank 200. FIG. [Figure 4] 3 is a schematic diagram showing another example of the structure of the tank 200. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described with reference to the drawings. Note that the drawings are schematic, and for example, the dimensions of each component, such as the thickness and width, may differ from the actual dimensions of the component. In addition, in the embodiments, substantially the same components are denoted by the same reference numerals, and the description thereof may be omitted.

[0010] In this specification, unless otherwise specified, "connect" includes not only direct connection but also indirect connection.

[0011] Fig. 1 is a schematic diagram showing a configuration example of an electrolysis device. The electrolysis device shown in Fig. 1 is a carbon dioxide electrolysis device.

[0012] The electrolysis device 1 shown in FIG. 1 includes an electrolysis cell 100, a power source 150, a tank 200, a cathode supply unit 301, and an anode supply unit 401.

[0013] The electrolysis cell 100 includes an anode 111, an anode flow path 112, an anode current collector 113, a cathode 121, a cathode flow path 122, a cathode current collector 123, and a separator 131. The electrolysis cell 100 includes these members sandwiched between a pair of support plates (not shown), and the plates are further fastened with bolts or the like.

[0014] The anode 111 is provided between the separator 131 and the anode flow path 112 and is in contact with them. The anode 111 oxidizes water (HO) in the anode solution to produce oxygen (O) and hydrogen ions (H + ) at the cathode 121 to generate hydroxide ions (OH - ) to produce oxygen and water.

[0015] The anode 111 preferably contains a catalytic material (anode catalytic material) capable of reducing the overvoltage of the oxidation reaction. Such catalytic materials include, for example, metals such as platinum (Pt), palladium (Pd), and nickel (Ni), alloys and intermetallic compounds containing these metals, binary metal oxides such as manganese oxide (Mn-O), iridium oxide (Ir-O), nickel oxide (Ni-O), cobalt oxide (Co-O), iron oxide (Fe-O), tin oxide (Sn-O), indium oxide (In-O), ruthenium oxide (Ru-O), lithium oxide (Li-O), and lanthanum oxide (La-O), ternary metal oxides such as Ni-Co-O, Ni-Fe-O, La-Co-O, Ni-La-O, and Sr-Fe-O, quaternary metal oxides such as Pb-Ru-Ir-O and La-Sr-Co-O, and metal complexes such as Ru complexes and Fe complexes.

[0016] The anode 111 is provided with a substrate having a structure capable of transferring liquid or ions between the separator 131 and the anode flow path 112, for example, a porous structure such as a mesh material, a punching material, a porous body, or a sintered metal fiber body. The substrate may be made of a metal material such as titanium (Ti), nickel (Ni), or iron (Fe), or an alloy containing at least one of these metals (for example, SUS), or may be made of the above-mentioned anode catalyst material. When an oxide is used as the anode catalyst material, it is preferable to form a catalyst layer by attaching or laminating the anode catalyst material on the surface of a substrate made of the above-mentioned metal material. The anode catalyst material preferably has nanoparticles, nanostructures, nanowires, etc. in order to enhance the oxidation reaction. A nanostructure is a structure in which nanoscale unevenness is formed on the surface of a catalyst material. In addition, it is not necessary to provide an oxidation catalyst on the anode 111. An oxidation catalyst layer provided other than on the anode 111 may be electrically connected to the anode 111.

[0017] The cathode 121 is in contact with the separator 131. The cathode 121 is supplied with an anode solution and ions from the separator 131, and with carbon dioxide gas from the cathode flow path 122. The cathode 121 is an electrode (reduction electrode) for generating a reduction reaction of carbon dioxide and a reduction reaction of a reduction product to generate a carbon compound. Examples of the carbon compound include carbon monoxide (CO), methane (CH4), ethane (C2H6), and the like. The reduction reaction at the cathode 121 may include a side reaction of generating hydrogen (H2) by generating a reduction reaction of water in addition to the reduction reaction of carbon dioxide.

[0018] The cathode 121 has a gas diffusion layer and a cathode catalyst layer provided on the gas diffusion layer. A porous layer denser than the gas diffusion layer may be disposed between the gas diffusion layer and the cathode catalyst layer. The gas diffusion layer is disposed on the cathode flow channel 122 side, and the cathode catalyst layer is disposed on the separator 131 side. The cathode catalyst layer may be embedded in the gas diffusion layer. The cathode catalyst layer preferably has catalyst nanoparticles or catalyst nanostructures. The gas diffusion layer is made of, for example, carbon paper or carbon cloth, and may be subjected to a water repellent treatment. The porous layer is made of a porous body having a smaller pore size than the carbon paper or carbon cloth.

[0019] By applying an appropriate water-repellent treatment to the gas diffusion layer, carbon dioxide gas reaches the cathode catalyst layer mainly by gas diffusion. The reduction reaction of carbon dioxide and the reduction reaction of the carbon compounds generated by the carbon dioxide occur near the boundary between the gas diffusion layer and the cathode catalyst layer, or near the cathode catalyst layer that has penetrated into the gas diffusion layer.

[0020] The cathode catalyst layer is preferably made of a catalyst material (cathode catalyst material) capable of reducing the overvoltage of the reduction reaction. Examples of such materials include metals such as gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), titanium (Ti), cadmium (Cd), zinc (Zn), indium (In), gallium (Ga), lead (Pb), and tin (Sn), metal materials such as alloys and intermetallic compounds containing at least one of these metals, carbon materials such as carbon (C), graphene, CNT (carbon nanotube), fullerene, and Ketjen Black, and metal complexes such as Ru complexes and Re complexes. The cathode catalyst layer can be applied in various shapes such as a plate, mesh, wire, particle, porous, thin film, and island shape.

[0021] The cathode catalyst material constituting the cathode catalyst layer preferably has nanoparticles of the above-mentioned metal material, nanostructures of the metal material, nanowires of the metal material, or a composite in which nanoparticles of the above-mentioned metal material are supported on a carbon material such as carbon particles, carbon nanotubes, graphene, etc. By using catalyst nanoparticles, catalyst nanostructures, catalyst nanowires, catalyst nanosupport structures, etc. as the cathode catalyst material, the reaction efficiency of the carbon dioxide reduction reaction in the cathode 121 can be increased.

[0022] The anode 111 and the cathode 121 can be connected to a power source 150. Examples of the power source 150 are not limited to a normal system power source or a battery, and may include a power source that supplies power generated by renewable energy such as solar cells or wind power generation. The use of renewable energy is environmentally preferable in terms of effective use of carbon dioxide. The power source 150 may further include a power controller that adjusts the output of the power source to control the voltage between the anode 111 and the cathode 121. The power source 150 may be provided outside the electrolysis device 1.

[0023] The anode flow channel 112 faces the anode 111. The anode flow channel 112 has a function of supplying an anode solution to the anode 111.

[0024] The anode solution preferably contains at least water (H2O). Carbon dioxide (CO2) is supplied from the cathode flow channel 122, so the liquid may or may not contain carbon dioxide (CO2).

[0025] The anode solution can be an aqueous solution (electrolyte) containing metal ions. For example, the aqueous solution contains phosphate ions (PO4 2- ), borate ion (BO3 3- ), sodium ion (Na + ), potassium ion (K + ), calcium ion (Ca 2+ ), lithium ion (Li + ), Cesium ion (Cs + ), magnesium ion (Mg 2+ ), chloride ion (Cl - ), hydrogen carbonate ion (HCO3 - ) and the like. In addition, aqueous solutions containing LiHCO3, NaHCO3, KHCO3, CsHCO3, phosphoric acid, boric acid, and the like may also be used.

[0026] The anode flow path 112 is provided on the surface of the flow path plate 114. The flow path plate 114 supplies an anode solution, which is an electrolyte, to the anode 111, and has a groove (recess) on the surface that forms the anode flow path 112. The material of the flow path plate 114 is preferably a material that has low chemical reactivity and high conductivity. Examples of such materials include metal materials such as Ti and SUS, and carbon. The anode flow path 112 may be provided on the anode current collector 113. The material of the flow path plate 114 includes, for example, a material that has low chemical reactivity and no conductivity. Examples of such materials include insulating resin materials such as acrylic resin, polyether ether ketone (PEEK), and fluororesin. The flow path plate 114 has an inlet and an outlet of the anode flow path 112, which are not shown, and screw holes for fastening.

[0027] The flow path plate 114 is mainly made of one material, but may be made of different materials and laminated together. Furthermore, a surface treatment may be applied to a part or the whole surface to impart hydrophilic or water-repellent properties.

[0028] The anode flow channel 112 has an inlet and an outlet, and the anode solution is supplied from an anode supply unit 401 via the inlet and discharged via the outlet. The anode solution flows through the anode flow channel 112 so as to come into contact with the anode 111.

[0029] The anode current collector 113 is electrically connected to the anode 111. The anode current collector 113 is in contact with the surface of the flow path plate 114 opposite to the anode flow path 112. The anode current collector 113 preferably contains a material that has low chemical reactivity and high conductivity. Examples of such materials include metal materials such as Ti and SUS, and carbon.

[0030] The cathode flow channel 122 faces the cathode 121. The cathode flow channel 122 has a function of supplying a fluid containing carbon dioxide (cathode gas) to the cathode 121. The fluid containing carbon dioxide may contain steam by being humidified. Compounds generated by the reduction reaction are mainly discharged from the cathode flow channel 122. The compounds generated by the reduction reaction differ depending on the type of reduction catalyst, etc. Together with such gas products, steam, or moisture obtained by condensation of steam contained in the humidified carbon dioxide gas, is discharged from the cathode flow channel 122.

[0031] The cathode flow path 122 is provided on the surface of the flow path plate 124. The flow path plate 124 has a groove (recess) on the surface that forms the cathode flow path 122. The material of the flow path plate 124 is preferably a material that has low chemical reactivity and high conductivity. Examples of such materials include metal materials such as Ti and SUS, and carbon. The material of the flow path plate 124 also includes a material that has low chemical reactivity and no conductivity. Examples of such materials include insulating resin materials such as acrylic resin, polyether ether ketone (PEEK), and fluororesin. The flow path plate 124 has screw holes for fastening (not shown). Also, packing (not shown) is sandwiched in front and behind each flow path plate as necessary. The cathode flow path 122 may be provided on the cathode current collector 123.

[0032] The cathode flow channel 122 has an inlet and an outlet, and a cathode gas such as carbon dioxide is supplied from a cathode supply unit 301 through the inlet, and a fluid containing the cathode gas is discharged through the outlet. The cathode gas flows through the cathode flow channel 122 so as to come into contact with the cathode 121.

[0033] The cathode flow channel 122 may have a land that contacts the cathode 121 for electrical contact with the cathode 121. The shape of the cathode flow channel 122 is not particularly limited as long as it is continuously connected, and may be, for example, a serpentine structure in which a long and thin flow channel is bent. This is preferable because the cathode gas flows uniformly on the surface of the cathode 121, allowing a uniform reaction to occur in the cathode 121.

[0034] The cathode gas may be supplied in a dry state. When the cathode gas is carbon dioxide gas, the carbon dioxide concentration of the cathode gas supplied from the cathode supply unit 301 to the cathode flow channel 122 does not have to be 100%. Gas containing carbon dioxide discharged from various facilities can also be used as the cathode gas.

[0035] The flow path plate 124 is mainly made of one material, but may be made of different materials and laminated together. Furthermore, a surface treatment may be applied to a part or the whole surface to impart hydrophilic or water-repellent properties.

[0036] The cathode current collector 123 is electrically connected to the cathode 121 of the electrolysis cell 100. The cathode current collector 123 preferably includes a material that has low chemical reactivity and high electrical conductivity. Examples of such materials include metal materials such as Ti and SUS, and carbon.

[0037] The separator 131 is disposed so as to separate the anode 111 and the cathode 121. The separator 131 includes an ion exchange membrane capable of transferring ions between the anode 111 and the cathode 121 and capable of separating the anode 111 and the cathode 121. Examples of the ion exchange membrane include a cation exchange membrane such as Nafion or Flemion, and an anion exchange membrane such as Neosepta, Selemion, or Sustenion. An alkaline solution is used as the electrolyte, and mainly OH - In the case where the movement of ions is assumed, it is preferable that the separator 131 is made of an anion exchange membrane. The ion exchange membrane may be made of a membrane having a basic skeleton of a hydrocarbon or a membrane having an amine group. However, other than the ion exchange membrane, a salt bridge, a glass filter, a porous polymer membrane, a porous insulating material, or the like may be applied to the separator 131 as long as the material is capable of moving ions between the anode 111 and the cathode 121. However, if gas flows between the anode 111 and the cathode 121, a circulation reaction due to reoxidation of the reduction product may occur. For this reason, it is preferable that the exchange of gas between the anode 111 and the cathode 121 is small. For this reason, care must be taken when using a porous thin film as the separator 131.

[0038] Next, a description will be given of an example of a method for driving the electrolysis cell 100. Here, the case where carbon monoxide is produced as a carbon compound will be mainly described, but the carbon compound as a reduction product of carbon dioxide is not limited to carbon monoxide.

[0039] First, water (HO) is oxidized to produce hydrogen ions (H + When a current is supplied between the anode 111 and the cathode 121 from the power source 150, an oxidation reaction of water (H2O) occurs at the anode 111 in contact with the anode solution. Specifically, as shown in the following formula (1), the H2O contained in the anode solution is oxidized to produce oxygen (O2) and hydrogen ions (H + ) is generated.

[0040] 2H2O → 4H + +O2+4e - (1)

[0041] H generated at anode 111 + The electrons (e - ) and H that migrated near the cathode 121 + As a result, a reduction reaction of carbon dioxide occurs. Specifically, as shown in the following formula (2), carbon dioxide supplied from the cathode flow path 122 to the cathode 121 is reduced to generate carbon monoxide. Also, as shown in the following formula (3), hydrogen ions receive electrons to generate hydrogen. At this time, hydrogen may be generated simultaneously with carbon monoxide.

[0042] CO2+2H + +2e - → CO+H2O (2) 2H + +2e - → H2···(3)

[0043] Next, carbon dioxide (CO2) is mainly reduced to hydroxide ions (OH -When a current is supplied between the anode 111 and the cathode 121 from the power source 150, water (H2O) and carbon dioxide (CO2) are reduced near the cathode 121 to produce carbon monoxide (CO) and hydroxide ions (OH - ) is produced. In addition, hydrogen is produced when water accepts electrons as shown in the following formula (5). In this case, hydrogen may be produced simultaneously with carbon monoxide. The hydroxide ions (OH - ) diffuses to the vicinity of the anode 111 and converts into hydroxide ions (OH - ) is oxidized to produce oxygen (O2).

[0044] 2CO2+2H2O+4e - → 2CO+4OH - (4) 2H2O+2e - → H2+2OH - (5) 4OH - → 2H2O+O2+4e - (6)

[0045] The electrolysis cell 100 can be specialized not only for the reduction of carbon dioxide, but also for producing any ratio of reduction products and hydrogen, such as, for example, producing carbon monoxide and hydrogen in a 1:2 ratio, followed by a chemical reaction to produce methanol.

[0046] Hydrogen is a cheap and easily available raw material from water electrolysis and fossil fuels, so the ratio of hydrogen does not need to be high. From these perspectives, it is preferable from the standpoint of economic efficiency and the environment that the ratio of carbon monoxide to hydrogen is at least 1, and preferably 1.5 or more.

[0047] The electrolysis device of the embodiment is not limited to a carbon dioxide electrolysis device, and may be, for example, a nitrogen electrolysis device. In the case of a nitrogen electrolysis device, ammonia can be produced by reducing nitrogen (N2) gas by the cathode 121. Other configurations of the nitrogen electrolysis device can be appropriately applied to the configurations of the carbon dioxide electrolysis device.

[0048] In the electrolysis cell 100, potassium (K + ) ions move to the cathode flow channel 122 side, and the K + It is known that the electrolyte concentration decreases as a result of ions flowing out of the cell from the outlet of the cathode flow channel 122 together with steam and moisture generated at the cathode 121. If the concentration of the electrolyte circulating on the anode 111 side decreases, the resistance of the electrolytic cell 100 increases, which can lead to problems such as performance degradation during long-term continuous operation of the electrolytic cell 100. To address this issue, it is conceivable to use a pump to return the liquid that has accumulated in a cathode effluent recovery bottle called a trap on the outlet side of the cathode flow channel 122 to an electrolyte tank that stores the electrolyte, which is connected to the anode flow channel 112. This will reduce the amount of K contained in the cathode effluent. + Since the ions can be returned to the electrolyte whose concentration has decreased, the decrease in the concentration of the electrolyte can be suppressed.

[0049] However, when a trap is used, the trap and a pump for moving the liquid from the trap to the electrolyte tank are required, which complicates the system around the electrolytic cell 100 and requires power to drive the pump. Furthermore, since the discharge rate of the liquid discharged from the cathode flow channel 122 is slower than the electrolyte circulation rate on the anode flow channel 112 side, the timing of moving the liquid accumulated in the trap to the electrolyte tank by the pump becomes intermittent. In addition, the K + The ion concentration is the K + It is known that the K concentration is higher than the ion concentration. + The ion-containing liquid is dripped into the electrolyte tank, so in this case, K + The ions diffuse through the electrolyte tank and + It takes time for the ion concentration to become uniform, and it is preferable to more efficiently implement a mechanism for preventing such a decrease in the concentration of the electrolyte.

[0050] In contrast, the electrolysis device 1 of the embodiment includes a tank 200, but does not include a trap or a pump for moving liquid from the trap to the electrolyte tank. Fig. 2 is a schematic diagram showing a structural example of the tank 200. The tank 200 includes a storage section 201, a storage section 202, a supply flow path 204, a discharge flow path 205, a supply flow path 206, a discharge flow path 207, and a discharge flow path 208.

[0051] The container 201 and the container 202 can contain a liquid including an anode solution. The container forming the container 201 and the container 202 may be made of glass, resin, metal, or the like. This container is a container with high airtightness between gas and liquid. When the container is made of metal, it is preferable that an insulating coating is applied to the inside in order to avoid leakage current due to electrical conduction through the anode solution. The insulating coating may be resin, glass, or rubber, and is preferably highly durable. The container may be provided with a water level sensor at one or several places in the container for measuring the height of the liquid level contained therein. In addition, the container may be provided with a sensor at one or several places in the container for measuring the ion concentration or electrical conductivity of the liquid. In addition, the container may be provided with a sensor at one or several places in the container for measuring the pressure or temperature inside the container. The operation of the electrolysis device 1 may be controlled by a controller or the like while referring to values ​​detected by these sensors.

[0052] The volume of the container is preferably large enough to hold the anode solution and condensed water for operating the electrolysis device 1, and may be, for example, but is not limited to, a volume of 1 L to 100 L. The shape of the container is not particularly limited, and may be, for example, a sphere, a cylinder, or a rectangular parallelepiped.

[0053] At least one further storage section may be provided between storage section 201 and storage section 202. It is preferable that the height of the lower part of each storage section is gradually decreased. It is more preferable that the anode solution is always present in all of the storage sections.

[0054] In addition, a pipe for recovering gas may be connected to each of the upper portions of the plurality of containers. This makes it difficult for the gas from the cathode flow channel 122 and the gas from the anode flow channel 112 to mix together even if the total amount of liquid in the container decreases or increases for some reason, so that the gas product can be recovered while maintaining a safe state.

[0055] The partition 203 is provided between the storage section 201 and the storage section 202, and separates the storage section 201 from the storage section 202. The partition 203 has at least one opening 203a connecting the storage section 201 and the storage section 202. No pump is formed in the middle of the opening 203a. The material of the partition 203 may be a semipermeable membrane, a polymer membrane, a liquid junction, or a porous material that allows liquid to pass but does not allow gas to pass easily, for example, a glass filter impregnated with liquid. In addition, an ion exchange membrane may be used, for example, a cation exchange membrane such as Nafion or Flemion. The liquid junction may be, for example, a sintered glass layer, a cellulose layer, an animal semipermeable membrane such as pulp, absorbent cotton, or fish skin, an ion exchange membrane, a solution having a condensed structure such as agar or gelatin, or the like. The opening 203a may be multiple.

[0056] The opening 203a allows liquid to pass through but not gas. This allows spatial separation of gas components (e.g., CO, CO2, and hydrogen (H2) gas) that come out together with the fluid discharged from the outlet of the cathode flow channel 122 and gas components (e.g., oxygen (O2) and CO2 gas) that come out together with the electrolyte discharged from the outlet of the anode flow channel 112. This allows valuable products (e.g., CO and H2 gas) that are the products of the carbon dioxide electrolysis cell to be separated from the liquid and collected, and furthermore, the H2 gas and O2 gas do not mix, which is effective in terms of safety.

[0057] The storage section 201 and the storage section 202 may be asymmetrical with respect to the partition wall 203. The two spaces formed by the walls provided inside the container may have the same shape and volume, or may have different shapes and volumes. The volume of the storage section 201 is preferably smaller than the volume of the storage section 202, and further, the upper portion 201a of the storage section 201 may be higher than the upper portion 202a of the storage section 202 relative to the lower portion 202b of the storage section 202. The lower portion 201b of the storage section 201 may be inclined so as to be lower toward the storage section 202 in order to promote the movement of liquid from the storage section 201 to the storage section 202.

[0058] The supply flow path 204 connects the container 201 and the outlet of the cathode flow path 122. The electrolysis device 1 can supply a fluid containing a cathode gas supplied from the cathode flow path 122 to the container 201 via the supply flow path 204. The supply flow path 204 is preferably provided at a position closer to the upper part 201a of the container 201 than to the lower part 201b. This allows the liquid from the cathode flow path 122 to accumulate in the lower part of the container, and the gas product from the cathode flow path 122 to accumulate in the upper part of the container. FIG. 2 shows, as an example, the supply flow path 204 provided in the upper part 201a.

[0059] The discharge flow path 205 is connected to the accommodation unit 201. The electrolysis device 1 is capable of discharging gaseous reduction products in the accommodation unit 201 from the accommodation unit 201 via the discharge flow path 205. The discharge flow path 205 is preferably provided at a position closer to the upper portion 201a than to the lower portion 201b of the accommodation unit 201. FIG 2 shows, as an example, the discharge flow path 205 provided in the upper portion 201a.

[0060] The supply flow path 206 connects the accommodation unit 202 and the outlet of the anode flow path 112. The electrolysis device 1 is capable of supplying a fluid containing an anode solution, which is supplied from the anode flow path 112, to the accommodation unit 202 via the supply flow path 206. The supply flow path 206 may be provided at a position closer to the upper portion 202a than to the lower portion 202b of the accommodation unit 202. FIG 2 shows, as an example, the supply flow path 206 provided in the upper portion 202a.

[0061] The discharge flow path 207 is connected to the accommodation unit 202. The electrolysis device 1 is capable of discharging, from the accommodation unit 202, the gaseous oxidation product supplied into the accommodation unit 202 via the discharge flow path 207. The discharge flow path 207 may be provided at a position closer to the upper part 202a than to the lower part 202b of the accommodation unit 202, or at a position closer to the lower part 202b than to the upper part 202a of the accommodation unit 202. FIG. 2 shows, as an example, the discharge flow path 207 provided in the upper part 202a.

[0062] The discharge flow path 208 connects the accommodation unit 202 and the anode supply unit 401. The electrolysis device 1 is capable of discharging a liquid containing an anode solution in the accommodation unit 202 from the accommodation unit 202 to the anode supply unit 401 via the discharge flow path 208. The discharge flow path 208 is preferably provided at a position closer to the lower part 202b than to the upper part 202a of the accommodation unit 202. FIG. 2 shows, as an example, the discharge flow path 208 provided in the side part 202c of the accommodation unit 202.

[0063] Each of the supply flow path 204, the discharge flow path 205, the supply flow path 206, the discharge flow path 207, and the discharge flow path 208 is a pipe. The pipe is formed, for example, using a material that is applicable to the container.

[0064] The cathode supply unit 301 is connected to the inlet of the cathode flow path 122. The cathode supply unit 301 can supply a cathode gas to the cathode flow path 122. In the case of a carbon dioxide electrolysis device, the cathode supply unit 301 can supply a cathode gas containing carbon dioxide gas to the cathode flow path 122. In the case of a nitrogen electrolysis device, the cathode supply unit 301 can supply a cathode gas containing nitrogen to the cathode flow path 122. The cathode supply unit 301 includes, for example, a tank that contains the cathode gas, and a mass flow controller that adjusts the flow rate of the cathode gas supplied from the tank to the cathode flow path 122. The supply of the cathode gas by the cathode supply unit 301 may be controlled by a controller or the like in accordance with detection signals from a water level sensor, a pressure sensor, a temperature sensor, or a sensor that measures the ion concentration or conductivity of the liquid, which are provided in the containers that form the storage unit 201 and the storage unit 202.

[0065] The anode supply unit 401 connects the discharge flow path 208 and the inlet of the anode flow path 112. The anode supply unit 401 can supply the fluid containing the anode solution discharged from the discharge flow path 208 to the anode flow path 112. This allows the anode solution to be circulated. The anode supply unit 401 includes, for example, a pump. The flow rate of the liquid containing the anode solution supplied to the anode 111 by the pump can be adjusted. The supply of the liquid by the anode supply unit 401 may be controlled by a controller or the like in accordance with detection signals from a water level sensor, a pressure sensor, a temperature sensor, or a sensor measuring the ion concentration or conductivity of the liquid, which are provided in the containers forming the storage unit 201 and the storage unit 202.

[0066] Next, an example of a method for driving the tank 200 will be described. When the electrolyte that has moved from the supply flow path 204 to the cathode flow path 122 side together with the cathode gas is supplied, the fluid containing the liquid and gas generated on the cathode 121 side is pushed by the pressure of the raw material gas supplied to the cathode 121 side and accumulates below the storage section 201. In the storage section 201, gas-liquid separation occurs due to the effect of gravity, etc. The separated liquid generated on the cathode 121 side containing metal ions accumulates below the storage section 201. Meanwhile, the storage section 202 is made to contain liquid at a substantially constant water level. When a fluid containing an anode solution is supplied to the accommodation unit 202 from the supply flow path 206, and the electrolyte solution that has moved to the cathode flow path 122 side together with the cathode gas from the supply flow path 204 is supplied to the accommodation unit 201, the electrolysis device 1 is driven to form a height difference between the liquid levels 211 and 212 so that the height of the liquid level 211 of the liquid contained in the accommodation unit 201 relative to the lower part 202b of the accommodation unit 202 is higher than the height of the liquid level 212 of the liquid contained in the accommodation unit 202 relative to the lower part 202b of the accommodation unit 202. As a result, K contained in the electrolyte flows from the accommodation unit 201 to the accommodation unit 202 through the opening 203a. + Ions such as ions move.

[0067] As a result, for example, the high K gas discharged from the outlet of the cathode flow channel 122 +The liquid with the ion concentration and the electrolyte circulating on the anode flow channel 112 side are mixed through the opening 203a. + Since ions diffuse, no large concentration gradient occurs, and K + The time required for the ion concentration to become uniform can be significantly shortened, and the electrolyte in the storage section 202 can be maintained at a high concentration. In addition, the device configuration can be simplified, so the installation area of ​​the device can be made smaller, and the configuration of the tank 200 does not require a trap or a pump for moving the liquid from the trap to the electrolyte tank, so the power required to operate the pump can be reduced.

[0068] The structure of the tank 200 is not limited to the example structure shown in Fig. 2. Figs. 3 and 4 are schematic diagrams showing other examples of the structure of the tank 200.

[0069] Tank 200 shown in Fig. 3 differs from tank 200 shown in Fig. 2 in that opening 203a is formed using piping 231. Pipe 231 connects storage section 201 and storage section 202. Pipe 231 may be formed using, for example, a material applicable to a container.

[0070] A valve controlled by an external signal may be provided in the middle of the pipe 231. The opening and closing of the valve is controlled by a controller or the like in response to detection signals from a water level sensor, a pressure sensor, a temperature sensor, or a sensor for measuring the ion concentration or electrical conductivity of the liquid, which are provided in the container.

[0071] Furthermore, the tank 200 shown in FIG. 3 differs from the tank 200 shown in FIG. 2 in that the height of the lower portion 201b relative to the lower portion 202b is made higher than the height of the lower portion 201b relative to the lower portion 202b, thereby forming a height difference between the liquid levels 211 and 212.

[0072] The tank 200 shown in Fig. 4 differs from the tank 200 shown in Fig. 2 in that the opening 203a is formed in a partition wall 232 that is impermeable to liquid and gas. The material of the partition wall 232 may be, for example, glass, resin, or metal. When the material of the partition wall 232 is metal, it is preferable that the partition wall 232 is electrically insulated from the outside of the container. The thickness of the partition wall 232 is not particularly limited as long as it has a strength sufficient to withstand the pressure difference in the internal space of the container, and may be, for example, 1 mm to 50 cm, but is not limited to this range.

[0073] 4 is provided at a position closer to the lower portion 201b of the storage portion 201 and the lower portion 202b of the storage portion 202 than to the upper portion 201a of the storage portion 201 and the upper portion 202a of the storage portion 202. The opening 203a may have a polygonal shape such as a triangle or a circle, or may be a combination of these. The shape of the opening 203a is preferably one that does not hinder the movement of liquid, but the periphery of the opening 203a may be flat or may have protrusions.

[0074] The size of the opening 203a is preferably a size that does not impede the movement of the liquid, and may be, for example, 1 mm to 10 cm, but is not limited to this range.

[0075] The number of openings 203a per unit area is preferably a value that does not impede the movement of liquid, and more preferably a value that allows the strength of the partition wall 203 to be maintained.

[0076] The above embodiment is presented as an example and is not intended to limit the scope of the invention. The above embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The above embodiment and its modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0077] 1...electrolysis device, 100...electrolysis cell, 111...anode, 112...anode flow path, 113...anode current collector, 114...flow path plate, 121...cathode, 122...cathode flow path, 123...cathode current collector, 124...flow path plate, 131...separator, 150...power source, 200...tank, 201...accommodation section, 201a...upper part, 201b...lower part, 202...accommodation section, 202a...upper part, 202b...lower part, 202c...side part, 203...partition wall, 203a...opening, 204...supply flow path, 205...discharge flow path, 206...supply flow path, 207...discharge flow path, 208...discharge flow path, 211...liquid level, 212...liquid level, 231...piping, 232...partition wall, 301...cathode supply section, 401...anode supply section.

Claims

1. an electrolysis cell comprising a cathode, an anode, a cathode flow passage facing the cathode, and an anode flow passage facing the anode; a tank having a first storage unit, a second storage unit, and an opening connecting the first storage unit and the second storage unit, the first storage unit and the second storage unit being capable of storing a liquid containing at least one ion, and forming a height difference between the first liquid level and the second liquid level such that a height of a first liquid level of the liquid stored in the first storage unit relative to a lower part of the second storage unit is higher than a height of a second liquid level of the liquid stored in the second storage unit relative to the lower part of the second storage unit, thereby transferring ions contained in the liquid from the first storage unit to the second storage unit via the opening; a first flow path connecting an outlet of the cathode flow path and the first container; a second flow passage connecting the second container and an outlet of the anode flow passage; 5. An electrolysis apparatus comprising: a) a first electrolysis tank; b) a first electrolysis tank; c) a second electrolysis tank; d) a first electrolysis tank; d) a second electrolysis tank;

2. The electrolysis apparatus according to claim 1 , wherein the tank has a partition wall provided between the first container portion and the second container portion and having the opening.

3. The electrolysis apparatus according to claim 1 or 2, wherein the tank has a pipe having the opening.

4. 4. The electrolysis device according to claim 1, wherein a lower portion of the first storage portion is provided at a higher position than a lower portion of the second storage portion.

5. 5. The electrolysis device according to claim 1, wherein the cathode is capable of reducing carbon dioxide to produce a carbon compound.

6. 5. The electrolysis device according to claim 1, wherein the cathode is capable of reducing nitrogen to produce ammonia.

7. 7. The electrolysis device according to claim 1, wherein the at least one ion comprises a potassium ion.

8. A method for operating an electrolysis device, comprising the steps of: The electrolysis device comprises: an electrolysis cell comprising a cathode, an anode, a cathode flow passage facing the cathode, and an anode flow passage facing the anode; a tank having a first storage section, a second storage section, and an opening connecting the first storage section and the second storage section, the first storage section and the second storage section being capable of storing a liquid containing at least one ion; a first flow path connecting an outlet of the cathode flow path and the first container; a second flow passage connecting the second container and an inlet of the anode flow passage; and no trap and no pump for moving the liquid from the trap to the tank; The driving method includes: A method for driving an electrolytic device, comprising: forming a height difference between the first liquid level and the second liquid level such that a height of a first liquid level of the liquid contained in the first storage unit relative to a lower part of the second storage unit is higher than a height of a second liquid level of the liquid contained in the second storage unit relative to the lower part of the second storage unit, thereby transferring ions contained in the liquid from the first storage unit to the second storage unit through the opening.

9. The driving method according to claim 8 , wherein the tank has a partition wall provided between the first container portion and the second container portion and having the opening.

10. The driving method according to claim 8 or 9, wherein the tank has a pipe having the opening.

11. 11. The driving method according to claim 8, wherein a lower portion of the first housing portion is provided at a higher position than a lower portion of the second housing portion.

12. The driving method according to claim 8 , wherein the cathode reduces carbon dioxide to produce a carbon compound.

13. The driving method according to claim 8 , wherein the cathode reduces nitrogen to produce ammonia.

14. The method according to claim 8 , wherein the at least one ion includes a potassium ion.

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