Electrochemical device, electrochemical manufacturing method, and control device

Abstract

An electrochemical device according to the present invention is provided with an electrolyte membrane, a cathode catalyst layer disposed on one side of the electrolyte membrane, and a cathode diffusion layer disposed so as to sandwich the cathode catalyst layer with the electrolyte membrane, and the pore diameter or the porosity differs in the thickness direction of the cathode diffusion layer.

Description

Electrochemical apparatus, electrochemical manufacturing method, and control device

[0001] The present invention relates to an electrochemical apparatus, an electrochemical manufacturing method, and a control device.

[0002] In recent years, the use of renewable energy sources such as solar, wind, hydroelectric, and geothermal power generation has been anticipated as a way to reduce carbon dioxide emissions during energy production. For example, a system has been devised that uses electricity derived from renewable energy to electrolyze water and produce hydrogen. Furthermore, organic hydride production equipment is attracting attention as an energy carrier for large-scale transportation and storage of hydrogen derived from renewable energy.

[0003] As a fuel cell, for example, a fuel cell is known that comprises an electrolyte membrane-electrode assembly having an electrolyte membrane, a cathode catalyst layer and a cathode-side gas diffusion layer sequentially arranged on one side of the electrolyte membrane, and an anode catalyst layer and an anode-side gas diffusion layer sequentially arranged on the other side of the electrolyte membrane (see, for example, Patent Document 1). In this organic hydride production apparatus, protons are generated at the anode by oxidation of water, these protons move to the cathode side through a diaphragm, and the hydride is produced by hydrogenating the hydride at the cathode with the protons.

[0004] Japanese Patent Application Publication No. 2010-92609

[0005] Although the reactions occurring inside the aforementioned organic hydride devices and fuel cells are different, both suffer from the problem that the generated water, gases, etc. tend to remain inside the cathode diffusion layer, leading to a decrease in current efficiency.

[0006] This disclosure is made in view of the above circumstances and aims to provide an electrochemical apparatus that can suppress the decrease in current efficiency due to water and gas remaining inside the cathode diffusion layer.

[0007] The electrochemical apparatus of the present disclosure comprises an electrolyte membrane, a cathode catalyst layer disposed on one side of the electrolyte membrane, and a cathode diffusion layer disposed so as to sandwich the cathode catalyst layer between the electrolyte membrane, wherein the pore diameter or porosity differs in the thickness direction of the cathode diffusion layer.

[0008] The electrochemical manufacturing method of this disclosure is an electrochemical manufacturing method using an electrochemical apparatus comprising an electrolyte membrane, a cathode catalyst layer disposed on one side of the electrolyte membrane, and a cathode diffusion layer disposed so as to sandwich the cathode catalyst layer between the electrolyte membrane, wherein the pore size or porosity differs in the thickness direction of the cathode diffusion layer, the electrolyte membrane moves protons, the cathode catalyst layer hydrogenates the hydride with the protons and electrons moving from the end plate side, and the cathode diffusion layer diffuses the hydride.

[0009] The control device of this disclosure comprises an electrolyte membrane, a cathode catalyst layer disposed on one side of the electrolyte membrane, and a cathode diffusion layer disposed so as to sandwich the cathode catalyst layer between the electrolyte membrane, and controls an electrochemical apparatus in which the pore size or porosity differs in the thickness direction of the cathode diffusion layer.

[0010] According to this disclosure, it is possible to provide an electrochemical apparatus that can suppress the decrease in current efficiency caused by water and gas remaining inside the cathode diffusion layer.

[0011] This is a schematic diagram showing an example of an electrolytic apparatus according to this embodiment. This is a schematic diagram showing an example of the structure of an electrolytic cell in the electrolytic apparatus according to this embodiment. This is a schematic diagram showing an example of the gradient structure of the cathode diffusion layer in the electrolytic apparatus as an electrochemical apparatus according to this embodiment. This is a schematic diagram showing an example of the analysis image of the simulation evaluation in the examples and comparative examples. This is a schematic diagram showing an example of a cross-section of the cathode 14 in Example 1. This is a schematic diagram showing an example of a cross-section of the cathode 14 in Comparative Example 1. This is a schematic diagram showing an example of a cross-section of the cathode 14 in Example 2. This is a schematic diagram showing an example of a cross-section of the cathode 14 in Example 3.

[0012] (Electrochemical Apparatus) The electrochemical apparatus of this disclosure is an electrolytic apparatus or a fuel cell. Hereinafter, an embodiment of the electrochemical apparatus of this disclosure will be described with reference to the drawings. The embodiments are illustrative and not limiting to the invention, and not all features or combinations thereof described in the embodiments are necessarily essential to the invention. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant explanations are omitted as appropriate. The scale and shape of each part shown in each figure are set for convenience to facilitate explanation and are not to be interpreted restrictively unless otherwise specified. Furthermore, when terms such as "first," "second," etc. are used in this specification or claims, these terms do not represent any order or importance, but are used to distinguish one configuration from another. Also, some parts that are not important for explaining the embodiment are omitted in each drawing. In this embodiment, "pore diameter," "porosity," "density," "carbon fiber width," etc., may be the average value of each measured value.

[0013] [First Embodiment] Figure 1 is a schematic diagram showing an example of an electrolytic apparatus as an electrochemical apparatus according to the first embodiment. Examples of electrolytic apparatuses include organic hydride production apparatuses. As shown in Figure 1, the electrochemical apparatus 1 mainly comprises an electrolytic cell 2, a power supply 4, an anode liquid supply device 6, a cathode liquid supply device 8, and a control device 10.

[0014] <Electrolytic Cell> Figure 2 is a schematic diagram showing an example of the structure of an electrolytic cell in an electrolytic apparatus as an electrochemical apparatus according to this embodiment. As shown in Figure 2, the electrolytic cell 2 has an anode 12, a cathode 14, an electrolyte membrane 20, an end plate 22a, and an end plate 22b.

[0015] <<Anode>> The anode 12 oxidizes the water in the anode solution to generate protons. The anode 12 may include an anode catalyst layer 24 and an anode diffusion layer 27. For example, the anode catalyst layer may be arranged in contact with the electrolyte membrane 20.

[0016] There are no particular restrictions on the catalyst included in the anode catalyst layer, and it can be appropriately selected according to the purpose. Examples include metals such as iridium (Ir), ruthenium (Ru), and platinum (pt), or oxides thereof.

[0017] The catalyst may be dispersed and supported on an electronically conductive substrate, or it may be directly coated onto the electrolyte membrane. There are no particular restrictions on the substrate, and it can be appropriately selected depending on the purpose, but it is preferably composed of a material mainly composed of metals such as titanium (Ti) or stainless steel (SUS). The electronic conductivity of the substrate may be imparted by coating. Examples of substrate forms include woven or nonwoven sheets, meshes, porous sintered bodies, foamed molded bodies (foams), and expanded metal.

[0018] The end plate 22a is a plate made of a metal such as stainless steel or titanium, and is installed on the side of the anode 12 opposite to the electrolyte membrane 20. As an example, the end plate 22a has groove-shaped channels on its main surface facing the anode 12.

[0019] The end plate 22a is provided with a first anode opening 26 and a second anode opening 28.

[0020] The first anode opening 26 is a so-called supply port for supplying anode fluid to the anode. The second anode opening 28 is a so-called discharge port for discharging anode fluid from the anode.

[0021] <<Cathode>> The cathode 14 hydrogenates the hydride in the cathode liquid with protons generated at the anode to produce an organic hydride. The cathode 14 includes a cathode catalyst layer 16 and a cathode diffusion layer 18. The cathode diffusion layer 18 is arranged so as to sandwich the cathode catalyst layer 16 between the electrolyte membrane 20. "Sandwiching" means that another layer may be included between the cathode diffusion layer 18 and the cathode catalyst layer 16, or between the electrolyte membrane 20 and the cathode catalyst layer 16.

[0022] The cathode diffusion layer has different pore sizes in the thickness direction, increasing from the cathode catalyst layer toward the end plate. This allows for efficient discharge of water, gas, etc., present inside the cathode diffusion layer.

[0023] The cathode diffusion layer has multiple steps with different pore diameters in the thickness direction of the cathode diffusion layer. Preferably, the pore diameters of the multiple steps of the cathode diffusion layer have a gradient structure. Figure 3 is a schematic diagram showing an example of a gradient structure of the cathode diffusion layer 18 in an electrolytic apparatus as an electrochemical device.

[0024] As shown in Figure 3, the cathode diffusion layer 18 has a first stage 18a positioned closest to the cathode catalyst layer 16, and a second stage 18b positioned next to the first stage 18a and close to the cathode catalyst layer 16, with the pore diameter of the first stage 18a being smaller than that of the second stage 18b, thus forming a so-called gradient structure. Although only the first stage 18a and the second stage 18b are shown in Figure 3, there may be a third stage or higher.

[0025] The pore size of the first stage is not particularly limited and can be appropriately selected according to the purpose, but is preferably 1 μm to 250 μm, more preferably 1 μm to 150 μm, and even more preferably 1 μm to 100 μm. If the pore size of the first stage is 1 μm or larger, smooth flow can be maintained within the cathode diffusion layer even under conditions where gases such as hydrogen are not generated. The pore size is a value measured, for example, by an X-ray CT device, and refers to the inner diameter of the pore.

[0026] The pore diameter of the second stage is not particularly limited as long as it is larger than the pore diameter of the first stage, and can be appropriately selected according to the purpose, but 2 μm to 299 μm is preferred, 50 μm to 299 μm is more preferred, and 100 μm to 299 μm is preferred.

[0027] The pore diameter of the second stage is preferably 1.1 to 300 times, and more preferably 1.1 to 6 times, that of the pore diameter of the first stage. This ensures that the rate at which water, gas, etc., migrates from the first stage to the second stage is approximately the same as the rate at which water, gas, etc., migrates from the second stage, thus maintaining a smoother flow within the cathode diffusion layer.

[0028] In FIG. 3, the cross-sectional shape of the pores is square, but there is no particular limitation, and it can be appropriately selected according to the purpose. For example, shapes such as a rectangular parallelepiped or a polygon may also be used.

[0029] The catalyst contained in the cathode catalyst layer is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include platinum and ruthenium. Further, the catalyst may be supported on a catalyst carrier having a porous structure. Examples of the catalyst carrier include electronically conductive materials such as porous carbon, porous metal, and porous metal oxide.

[0030] The catalyst may be coated with an ionomer. For example, the catalyst carrier carrying the catalyst is coated with an ionomer. The ionomer is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include perfluorosulfonic acid polymers such as Nafion (registered trademark) and Flemion (registered trademark). Note that it is preferable that the ionomer partially covers the catalyst. Thereby, the three elements (the hydride, the proton, and the electron) necessary for the electrochemical reaction in the cathode catalyst layer can be efficiently supplied to the reaction field.

[0031] The material of the cathode diffusion layer is not particularly limited and can be appropriately selected according to the purpose. However, a conductive material such as carbon or metal is preferable. As an aspect of the cathode diffusion layer, a porous body such as a sintered body of fibers or particles or a foam molded body is preferable. Specific examples of the porous body include non-woven fabric, felt, carbon paper, and spunlace. When the cathode diffusion layer contains carbon paper, the width of the carbon fibers of the carbon paper is preferably 1 μm to 50 μm.

[0032] The end plate 22b is, for example, a plate material made of a metal such as stainless steel or titanium, and is installed on the side of the cathode 14 opposite to the electrolyte membrane 20. As an example, the end plate 22b has a groove-shaped flow path on the main surface facing the cathode 14 side. The end plate 22b may be coated with a metal such as platinum having high conductivity.

[0033] The end plate 22b is provided with a first cathode opening 30 and a second cathode opening 32 that communicate the inside and outside of the cathode 14.

[0034] The first cathode opening 30 is a so-called supply port that supplies the cathode liquid to the cathode 14. The second cathode opening 32 is a so-called discharge port that discharges the cathode liquid from the cathode 14. Note that the first cathode opening 30 may be a so-called discharge port that discharges the cathode liquid from the cathode 14, and the second cathode opening 32 may be a so-called supply port that supplies the cathode liquid to the cathode 14.

[0035] <<Electrolyte membrane>> The electrolyte membrane 20 is sandwiched between the anode 12 and the cathode 14.

[0036] The electrolyte membrane 20 is composed of a solid polymer electrolyte membrane having proton conductivity, and moves protons from the anode 12 side to the cathode 14 side. The solid polymer electrolyte membrane is not particularly limited as long as it is a material through which protons conduct, and can be appropriately selected according to the purpose. Examples include fluorine-based ion exchange membranes having sulfonic acid groups, hydrocarbon-based membranes, and the like.

[0037] The anode liquid is not particularly limited as long as it contains water, and can be appropriately selected according to the purpose. Examples include aqueous sulfuric acid solutions, aqueous nitric acid solutions, aqueous hydrochloric acid solutions, pure water, ion-exchanged water, and the like.

[0038] The cathode 14 is supplied with the cathode liquid by the cathode liquid supply device 8. The cathode liquid contains an organic hydride raw material (substrate to be hydrogenated) for supplying to the cathode 14. As an example, the cathode liquid does not contain organic hydride before the start of operation of the electrolysis device 1, and becomes a mixed liquid of the substrate to be hydrogenated and organic hydride by mixing the organic hydride generated by electrolysis after the start of operation. It is preferable that the substrate to be hydrogenated and the organic hydride are liquids at 20°C and 1 atm.

[0039] The hydrogenated substance and organic hydride are not particularly limited as long as they are organic compounds that can be reversibly subjected to hydrogenation / dehydrogenation reactions to add / remove hydrogen. They can be appropriately selected according to the purpose, and examples include acetone-isopropanol compounds, benzoquinone-hydroquinone compounds, and aromatic hydrocarbon compounds. Among these, aromatic hydrocarbon compounds are preferred from the viewpoint of transportability during energy transport.

[0040] Aromatic hydrocarbon compounds are compounds containing at least one aromatic ring, and examples include benzene, alkylbenzene, naphthalene, alkylnaphthalene, anthracene, and diphenylethane.

[0041] Alkylbenzenes include compounds in which 1 to 4 hydrogen atoms of an aromatic ring are substituted with a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group, and examples include toluene, xylene, mesitylene, ethylbenzene, and diethylbenzene.

[0042] Alkylnaphthalenes include compounds in which the 1st to 4th hydrogen atoms of an aromatic ring are substituted with a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group, such as methylnaphthalene.

[0043] These may be used individually or in combination of two or more types.

[0044] The hydrogenate is preferably at least one of toluene and benzene. Nitrogen-containing heterocyclic aromatic compounds such as pyridine, pyrimidine, pyrazine, quinoline, isoquinoline, N-alkylpyrrole, N-alkylindole, and N-alkyldibenzopyrrole can also be used as hydrogenates.

[0045] Organic hydrides are obtained by hydrogenating the aforementioned hydrogenated substances, and examples include cyclohexane, methylcyclohexane, dimethylcyclohexane, and piperidine.

[0046] When toluene (TL) is used as an example of the hydrogenate, the following reaction occurs in electrolytic cell 2. Note that when toluene is used as the hydrogenate, the resulting organic hydride is methylcyclohexane (MCH).

[0047] [Electrode reaction at the anode] (Mathematics 1) 3H ２ O → 3 / 2O ２ +6H ＋ +6e －

[0048] [Electrode reaction at the cathode] (Mathematics 2) TL + 6H ＋ +6e － →MCH

[0049] The electrode reaction at anode 12 and the electrode reaction at cathode 14 proceed in parallel. Protons generated by the electrolysis of water at anode 12 are supplied to cathode 14 via the electrolyte membrane 20. Electrons generated by the electrolysis of water are supplied to cathode 14 via end plate 22a, the external circuit, and end plate 22b. The protons and electrons supplied to cathode 14 are used for the hydrogenation of toluene at cathode 14. This generates methylcyclohexane.

[0050] According to the electrolytic apparatus 1 of this embodiment, the electrolysis of water and the hydrogenation reaction of the hydrogenate can be performed in a single step. Therefore, compared to conventional technology that produces organic hydrides in a two-step process including a process to produce hydrogen by water electrolysis and a process to chemically hydrogenate the hydrogenate in a reactor such as a plant, the production efficiency of organic hydrides can be increased. Furthermore, since a reactor for chemical hydrogenation and a high-pressure vessel for storing hydrogen produced by water electrolysis are not required, equipment costs can be significantly reduced.

[0051] At cathode 14, along with the main reaction, the hydrogenation of the hydride, a side reaction, the generation of hydrogen gas, may occur. This side reaction is more likely to occur as the supply of the hydride to cathode 14 becomes insufficient.

[0052] [Possible side reactions occurring at the cathode] (Math 3) 2H＋ +2e － →H ２

[0053] <Anode liquid supply device> As shown in FIG. 1, the anode liquid supply device 6 supplies anode liquid to the anode 12. The anode liquid supply device 6 includes an anode liquid tank 36, a gas-liquid separation unit 38, a first anode pipe 40, a second anode pipe 42, a third anode pipe 44, a first anode pump 46, and a second anode pump 48.

[0054] The gas-liquid separation unit 38 can be constituted by a known gas-liquid separation tank.

[0055] The first anode pump 46 and the second anode pump 48 can be constituted by known pumps such as a gear pump or a cylinder pump. Note that the anode liquid supply device 6 may circulate the anode liquid using a liquid feeding device other than a pump.

[0056] The anode liquid tank 36 stores the anode liquid to be supplied to the anode 12. The anode liquid tank 36 is connected to the anode 12 by the first anode pipe 40. One end side of the first anode pipe 40 is connected to the anode liquid tank 36, and the other end side is connected to the first anode opening 26. A first anode pump 46 is provided in the middle of the first anode pipe 40.

[0057] The gas-liquid separation unit 38 is connected to the anode 12 by the second anode pipe 42. One end side of the second anode pipe 42 is connected to the second anode opening 28, and the other end side is connected to the gas-liquid separation unit 38. Further, the gas-liquid separation unit 38 is connected to the anode liquid tank 36 by the third anode pipe 44. A second anode pump 48 is provided in the middle of the third anode pipe 44.

[0058] The anode liquid in the anode liquid tank 36 flows into the anode 12 through the first anode opening 26 via the first anode piping 40, driven by the first anode pump 46. The anode liquid is supplied to the anode 12 in an upflow manner and used for the electrode reaction at the anode 12. The anode liquid in the anode 12 flows into the gas-liquid separation unit 38 via the second anode piping 42. Oxygen gas is generated at the anode 12 by the electrode reaction. Therefore, the anode liquid discharged from the anode 12 contains oxygen gas. The gas-liquid separation unit 38 separates the oxygen gas from the anode liquid and discharges it outside the system. The anode liquid from which the oxygen gas has been separated is returned to the anode liquid tank 36 via the third anode piping 44, driven by the second anode pump 48.

[0059] <Cathode Liquid Supply Device> As shown in Figure 1, the cathode liquid supply device 8 supplies cathode liquid to the cathode 14. The cathode liquid supply device 8 includes a cathode liquid tank 50, a gas-liquid separation unit 52, an oil-water separation unit 54, a gas tank 56, first cathode piping 58 to sixth cathode piping 72, first cathode pumps 74 to fourth cathode pumps 80, and first on-off valves 84 to fourth on-off valves 94.

[0060] The gas-liquid separation unit 52 can be configured using a known gas-liquid separation tank.

[0061] The oil-water separation unit 54 can be configured with a known oil-water separation tank.

[0062] The first cathode pumps 74 to the fourth cathode pumps 80 can be composed of known pumps such as gear pumps or cylinder pumps. The cathode fluid supply device 8 may also circulate the cathode fluid using a fluid delivery device other than a pump.

[0063] The first to fourth on-off valves 84 to 94 can be composed of known valves such as solenoid valves or air-driven valves.

[0064] The cathode fluid tank 50 stores the cathode fluid supplied to the cathode 14. The cathode fluid tank 50 is connected to the cathode 14 by a first cathode pipe 58. One end of the first cathode pipe 58 is connected to the cathode fluid tank 50, and the other end is connected to the first cathode opening 30. A first cathode pump 74 and a first on-off valve 84 are provided in the middle of the first cathode pipe 58. The first cathode pump 74 is positioned closer to the cathode 14 than the first on-off valve 84.

[0065] The gas-liquid separation unit 52 is connected to the cathode 14 by a second cathode pipe 60. One end of the second cathode pipe 60 is connected to the second cathode opening 32, and the other end is connected to the gas-liquid separation unit 52. A second on-off valve 86 is provided in the middle of the second cathode pipe 60.

[0066] The oil-water separator 54 is connected to the gas-liquid separator 52 by a third cathode pipe 62. A second cathode pump 76 and a third on-off valve 88 are provided in the middle of the third cathode pipe 62. The second cathode pump 76 is positioned closer to the gas-liquid separator 52 than the third on-off valve 88. The oil-water separator 54 is also connected to the cathode liquid tank 50 by a fourth cathode pipe 64. A third cathode pump 78 is provided in the middle of the fourth cathode pipe 64. Furthermore, a fifth cathode pipe 66 is connected to the oil-water separator 54. One end of the fifth cathode pipe 66 is connected to the oil-water separator 54, and the other end is connected to, for example, a drainage tank (not shown). A fourth cathode pump 80 and a water flow sensor 96 are provided in the middle of the fifth cathode pipe 66. The water flow sensor 96 detects the flow rate of water flowing through the fifth cathode pipe 66. The water flow sensor 96 can be configured using a known flow meter.

[0067] The gas tank 56 is connected to the cathode 14 by a sixth cathode pipe 72. One end of the sixth cathode pipe 72 is connected to the gas tank 56, and the other end is connected to the second cathode opening 32 via the second cathode pipe 60. A fourth on-off valve 94 is provided in the middle of the sixth cathode pipe 72. In this embodiment, the other end of the sixth cathode pipe 72 is connected to the region of the second cathode pipe 60 on the cathode 14 side of the second on-off valve 86, thereby connecting to the second cathode opening 32 via the second cathode pipe 60. However, the configuration is not limited to this, and the sixth cathode pipe 72 may be directly connected to the second cathode opening 32.

[0068] As shown in Figure 1, the cathode liquid supply device 8 can form a first path for the cathode liquid by comprising a cathode liquid tank 50, a first cathode pipe 58, a cathode 14, a second cathode pipe 60, a gas-liquid separation unit 52, a third cathode pipe 62, an oil-water separation unit 54, and a fourth cathode pipe 64. In the first path, an upflow of cathode liquid is formed within the cathode 14. In this disclosure, "upflow" of the cathode liquid refers to the flow of cathode liquid into the cathode 14 from the first cathode opening 30 located below and the discharge of cathode liquid from the second cathode opening 32 located above. Alternatively, a "downflow" may be used, in which cathode liquid flows into the cathode 14 from the second cathode opening 32 located above and is discharged from the first cathode opening 30 located below.

[0069] Specifically, the cathode fluid in the cathode fluid tank 50 flows into the cathode 14 through the first cathode piping 58 via the first cathode opening 30, driven by the first cathode pump 74. The first on-off valve 84 is in the open state, allowing the flow of cathode fluid from the cathode fluid tank 50 to the first cathode opening 30. The cathode fluid is supplied to the cathode 14 in an upflow manner.

[0070] The cathode liquid in cathode 14 flows into the gas-liquid separation unit 52 via the second cathode piping 60. The second on-off valve 86 is in the open state, allowing the flow of cathode liquid from the second cathode opening 32 to the gas-liquid separation unit 52. The fourth on-off valve 94 is in the closed state, blocking the flow of cathode liquid from the second cathode opening 32 to the gas tank 56. As described above, hydrogen gas is generated in cathode 14 by a side reaction. Therefore, the cathode liquid discharged from cathode 14 contains hydrogen gas. The gas-liquid separation unit 52 separates the hydrogen gas from the cathode liquid and discharges it outside the system.

[0071] The cathode liquid from which hydrogen gas has been separated flows into the oil-water separator 54 via the third cathode piping 62, driven by the second cathode pump 76. The third on-off valve 88 is in the open state, allowing the flow of cathode liquid from the gas-liquid separator 52 to the oil-water separator 54.

[0072] Water may move from the anode 12 along with protons into the cathode 14, and consequently, the cathode fluid discharged from the cathode 14 may contain water. The oil-water separator 54 separates the water from the cathode fluid. The separated water is discharged to the drain tank via the fifth cathode piping 66 by the drive of the fourth cathode pump 80. The amount of water separated from the cathode fluid by the oil-water separator 54, in other words, the amount of water discharged from the cathode 14, is detected by the water volume sensor 96. The cathode fluid from which the water has been separated is returned to the cathode fluid tank 50 via the fourth cathode piping 64 by the drive of the third cathode pump 78.

[0073] Although only one electrolytic cell 2 is shown in Figure 1, the electrolytic device 1 may have multiple electrolytic cells 2. In this case, each electrolytic cell 2 is aligned in orientation such that, for example, the anode 12 and cathode 14 are in the same position, and is stacked with a conductive plate in between adjacent electrolytic cells 2. This connects each electrolytic cell 2 electrically in series. The conductive plate is made of a conductive material such as metal. Note that each electrolytic cell 2 may be connected in parallel, or a combination of series and parallel connections may be used.

[0074] <Power Supply> Power supply 4 is a DC power supply that supplies power to the electrolytic cell 2. When power is supplied to the electrolytic cell 2 from power supply 4, a predetermined electrolytic voltage is applied between the anode 12 and cathode 14 of the electrolytic cell 2, and an electrolytic current flows. Power supply 4 receives power from the power supply device 34 and supplies power to the electrolytic cell 2.

[0075] The power supply device 34 is a power supply device that supplies power to the power supply 4 of the electrolytic device 1 in DC, and has at least one of a first power supply device 341 and a second power supply device 342. It may also have a power conversion unit that converts the output voltage of the first power supply device 341 to a predetermined voltage.

[0076] The first power supply device 341 can be, for example, a power generation device that generates electricity derived from renewable energy. Specific examples include wind power generation devices, solar power generation devices, hydroelectric power generation devices, geothermal power generation devices, wave power generation devices, thermoelectric power generation devices, and biomass power generation devices.

[0077] The power conversion unit converts the output voltage of the first power supply device 341 to a predetermined voltage. For example, a DC / DC converter can be used as the power conversion unit. When power is input in AC from the first power supply device 341, the power conversion unit converts the voltage using a transformer, rectifies it using a bridge diode, smooths it using a smoothing electrolytic capacitor, and supplies power to the electrolytic cell 2 from the output terminal. The power conversion unit may also convert the output voltage of the second power supply device 342 to a predetermined voltage.

[0078] The second power supply device 342 can be, for example, a storage battery, a thermal power plant that burns fossil fuels such as natural gas and coal. The power from the second power supply device 342 may be used as a secondary power source when the power supplied from the first power supply device 341 is insufficient. As a result, the electrolytic device 1 can operate stably by supplying power from the second power supply device 342 to the electrolytic cell 2 in addition to the power supplied from the first power supply device 341. Furthermore, if the second power supply device 342 is composed of a storage battery, the second power supply device 342 is charged by receiving power from the first power supply device 341, thereby reducing the CO2 emissions generated from the power supply device 34. ２Emissions can be reduced. The second power supply device 342 may supply power to the power source 4 independently of the first power supply device 341. The second power supply device 342 may supply power to the power source 4 based on control by the control device 10.

[0079] The power supply device 34 may also include a storage battery, which stores the electricity generated by at least one of the first power supply device 341 and the second power supply device 342, and supply power from the storage battery to the electrolytic device 1 as needed.

[0080] <Control device> The control device 10 controls the supply of power from the power supply 4 to the electrolytic cell 2. The potentials of the anode 12 and cathode 14 are controlled by the control device 10. The control device 10 is implemented as a hardware configuration using elements and circuits such as a computer's CPU and memory, and as a software configuration using a computer program, but in Figure 1 it is depicted as a functional block realized through the cooperation of these. It will be obvious to those skilled in the art that this functional block can be realized in various forms by combinations of hardware and software.

[0081] The control device 10 receives at least one of the following signals from a detection unit 98 provided in the electrolytic cell 2: a signal indicating the voltage of the electrolytic cell 2, a signal indicating the potential of the anode 12, and a signal indicating the potential of the cathode 14. The detection unit 98 can detect the potential of each electrode and the voltage of the electrolytic cell 2 using known methods. The detection unit 98 may have, for example, a known voltmeter.

[0082] When the detection unit 98 detects the potential of the anode 12 or the cathode 14, a reference electrode is provided on the electrolyte membrane 20. The reference electrode is maintained at a reference electrode potential. For example, the reference electrode is a reversible hydrogen electrode (RHE). One terminal of the detection unit 98 is connected to the reference electrode, and the other terminal is connected to the electrode to be detected, so that the potential of the electrode relative to the reference electrode is detected. Also, when the detection unit 98 detects the voltage of the electrolytic cell 2, one terminal of the detection unit 98 is connected to the anode 12, and the other terminal is connected to the cathode 14, so that the potential difference between the two electrodes, i.e., the voltage, is detected. The detection unit 98 transmits a signal indicating the detection result to the control device 10.

[0083] The detection unit 98 includes a current detection unit that detects the current flowing between the anode 12 and the cathode 14. The current detection unit is composed of, for example, a known ammeter. The current value detected by the current detection unit is input to the control device 10.

[0084] The control device 10 may have information on the current-voltage characteristics (I-V characteristics) of the electrolytic cell 2 stored in advance. If the control device 10 has information on the I-V characteristics, this information may be updateable at will. The I-V characteristics of the electrolytic cell 2 are characteristics determined according to the catalyst composition of each electrode, the type of diffusion layer and substrate, the type of electrolyte membrane 20, the flow path structure of the anode and cathode liquids in the electrolytic cell 2, the dimensions of each part, etc., and can be measured and known in advance. In this case, the control device 10 can receive a signal indicating the amount of power supplied from the power supply device 34 to determine the amount of power that can be supplied to the electrolytic cell 2 from the power supply 4, and calculate the voltage value to be applied to the electrolytic cell 2 from the I-V characteristics, that is, control the current value flowing through the electrolytic cell 2.

[0085] The control device 10 can control the current value to be applied to the electrolytic cell 2. There are no particular restrictions on the current value applied to the electrolytic cell 2; it can be appropriately selected according to the purpose, but 0.01 A / cm is a reasonable value. ２ ~4.0 A / cm ２ It is preferable.

[0086] The control device 10 controls the anode fluid supply device 6 and the cathode fluid supply device 8. Specifically, the control device 10 controls the driving of the first anode pump 46, the second anode pump 48, and the first cathode pumps 74 to the fourth cathode pumps 80. The control device 10 also controls the opening and closing of the first on-off valves 84 to the fourth on-off valves 94. The control device 10 also receives signals indicating detection results from the water volume sensor 96.

[0087] The control device 10 can control the amount of hydrate flowing into the cathode diffusion layer 18. Specifically, the cathode liquid supply device 8 controls the driving of the first cathode pump 74 to the fourth cathode pump 80 and the opening and closing of the first on-off valve 84 to the fourth on-off valve 94. This controls the amount of hydrate flowing into the cathode diffusion layer 18. There are no particular restrictions on the amount of hydrate flowing into the cathode diffusion layer 18, and it can be appropriately selected according to the purpose, but 0.2 mL / min / cm² per electrode area is recommended. ２ ~3.0mL / min / cm ２ It is preferable.

[0088] As described above, in cathode 14, the hydrogenation reaction of the hydride material occurs as the main reaction, and a hydrogen generation reaction may occur as a side reaction. The occurrence of side reactions leads to a decrease in the Faraday efficiency of the electrolytic device 1. In addition, protons may move from the anode 12 side to the cathode 14 side accompanied by water, causing water to accumulate in cathode 14. Since water obstructs the flow of the hydride material, if a large amount of water accumulates in cathode 14, the supply of the hydride material to the reaction field in cathode 14 decreases, making it easier for side reactions to proceed. Furthermore, the hydrogen gas generated in the side reactions also obstructs the flow of the hydride material, so the hydrogen gas generated in the side reactions makes it even easier for side reactions to occur. Therefore, it is preferable to discharge the hydrogen gas and water accumulated in cathode 14 from cathode 14.

[0089] [Modification of the First Embodiment] An example of a fuel cell as an electrochemical device according to a modification of the first embodiment will be described. In the first embodiment, components identical to those already described are denoted by the same reference numerals and their descriptions are omitted. In the fuel cell as an electrochemical device according to a modification of the first embodiment, the pore diameter of the cathode differs in the thickness direction of the cathode diffusion layer, becoming smaller from the cathode catalyst layer toward the end plate. This allows the gas present inside the cathode diffusion layer to be efficiently transferred to the cathode catalyst layer side.

[0090] The cathode diffusion layer has multiple steps with different pore diameters in the thickness direction of the cathode diffusion layer. Preferably, the pore diameters of the multiple steps in the cathode diffusion layer have a gradient structure.

[0091] The cathode diffusion layer has a first stage located closest to the cathode catalyst layer and a second stage located next to the cathode catalyst layer, with the pore diameter of the first stage being larger than that of the second stage, thus forming a so-called gradient structure. The cathode diffusion layer may also have a third stage or higher.

[0092] The pore size of the first stage is not particularly limited and can be appropriately selected depending on the purpose, but 2 μm to 299 μm is preferred, 50 μm to 299 μm is more preferred, and 100 μm to 299 μm is even more preferred.

[0093] The pore diameter of the second stage is not particularly limited as long as it is larger than the pore diameter of the first stage, and can be appropriately selected according to the purpose, but 1 μm to 250 μm is preferred, 1 μm to 150 μm is more preferred, and 1 μm to 100 μm is even more preferred.

[0094] The pore diameter of the first stage is preferably 1.1 to 300 times, and more preferably 1.1 to 6 times, that of the pore diameter of the second stage.

[0095] [Second Embodiment] An example of an electrolytic apparatus as an electrochemical apparatus according to the second embodiment will be described. In the first embodiment, components identical to those already described will be given the same reference numerals and their descriptions will be omitted. In the electrolytic apparatus as an electrochemical apparatus according to the second embodiment, the cathode has at least one of the density and porosity different in the thickness direction of the cathode diffusion layer.

[0096] A void refers to a region within the cathode diffusion layer where no fibers exist, on an arbitrary plane located parallel to the longitudinal direction of the cathode diffusion layer. Voids can be measured, for example, by acquiring X-CT images and measuring them using 3D-CAD software. The void volume ratio can be determined by (volume of voids / volume of diffusion layer) in a given space, and the void area ratio can be determined by (area of ​​voids / area of ​​diffusion layer) in a given plane. In this application, void ratio includes both void volume ratio and void area ratio.

[0097] In the cathode diffusion layer, the porosity of a first plane located parallel to the longitudinal direction of the cathode diffusion layer is smaller than the porosity of a second plane located closer to the end plate than the first plane. Here, the first plane is, for example, a plane containing pores located closest to the catalyst. The second plane is, for example, a plane containing pores adjacent to the pores located closest to the catalyst. More specifically, for example, if the pore diameter of pore A located closest to the catalyst layer in the cathode diffusion layer is r1, and the pore diameter of pore B located further from the catalyst layer than pore A and adjacent to pore A is r2, then the first plane is a plane located at any distance from the catalyst layer to r1, and the second plane is a plane located at any distance from r1 to r1+r2.

[0098] The porosity of the second plane in the cathode diffusion layer is not particularly limited and can be appropriately selected depending on the purpose, but for example, it is preferably 1.01 times or more the porosity of the first plane.

[0099] Density refers to the mass of the cathode diffusion layer in any cubic region located parallel to the longitudinal direction of the cathode diffusion layer. Specifically, it is the mass of the cathode diffusion layer between a first plane located parallel to the longitudinal direction of the cathode diffusion layer and a second plane located closer to the end plate than the first plane. Density can be measured, for example, by acquiring an X-ray CT image and measuring it using 3D-CAD software.

[0100] In the cathode diffusion layer, the density in the region between a first plane located parallel to the longitudinal direction of the cathode diffusion layer and a second plane located closer to the end plate than the first plane (hereinafter sometimes referred to as the "first region") is greater than the density in the region between a third plane located closer to the end plate than the second plane and a fourth plane located closer to the end plate than the third plane (hereinafter sometimes referred to as the "second region").

[0101] The density of the second region in the cathode diffusion layer is not particularly limited and can be appropriately selected depending on the purpose, but for example, it is preferably 0.99 times or less the density of the first region.

[0102] (Organic Hydride Production System) An organic hydride production system equipped with an electrolytic device according to an embodiment of the present invention will be described with reference to Figure 1. As shown in Figure 1, the organic hydride production system 3 of the present invention comprises an electrolytic device 1 and a power supply device 34. In the organic hydride production system 3, the description of the components that overlap with the above-mentioned (electrolytic device) will be omitted.

[0103] The organic hydride production system 3 comprises an electrolytic device 1 and, as a power supply device 34, at least one of a first power supply device that supplies electricity derived from renewable energy to the power supply of the electrolytic device 1, and a second power supply device that supplies electricity derived from fossil fuels to the power supply of the electrolytic device 1.

[0104] For example, the organic hydride production system 3 comprises the electrolytic device 1 described above and a first power supply device 341. This allows the organic hydride production system 3 to efficiently produce organic hydrides by generating them in the electrolytic device 1 using renewable energy-derived power supplied from the first power supply device 341.

[0105] The organic hydride production system 3 can produce organic hydrides using electricity derived from renewable energy generated by the first power supply device 341, thereby reducing the consumption of fossil fuels and CO2 associated with hydrogen production. ２ Emissions can be reduced.

[0106] The organic hydride production system 3 can stably operate the electrolytic device 1 by supplying power generated by the second power supply device 342 to the electrolytic cell 2 of the electrolytic device 1 if the power supplied from the first power supply device 341 to the electrolytic cell 2 is insufficient. As a result, the organic hydride production system 3 can stably produce organic hydrides in the electrolytic device 1.

[0107] In the organic hydride production system 3, when the power supply device 34 supplies power originating from the first power supply device 341, that is, power generated by the first power supply device 341, to the electrolytic cell 2 of the electrolytic device 1, the electrolytic device 1 operates. If power originating from the first power supply device 341 is not supplied to the electrolytic cell 2, the electrolytic device 1 may stop operating.

[0108] Note that "operation" refers to the time when the electrolytic device 1 is producing organic hydride, which is its primary purpose. Therefore, even when the electrolytic device 1 is stopped, power may be supplied to the electrolytic device 1 from the second power supply device 342.

[0109] As described above, the organic hydride production system 3 can efficiently generate organic hydrides directly as energy carriers for transporting and storing energy-derived hydrogen, such as renewable energy, using a hydride without passing through hydrogen gas. For this reason, the organic hydride production system 3 can be effectively used as a device for producing energy carriers used for transporting and storing electricity generated by the first power supply device 341 and the second power supply device 342. In particular, by using the organic hydride production system 3, renewable energy can be transported and stored via organic hydrides, thereby enabling efficient and waste-free utilization of renewable energy. Therefore, the organic hydride production system 3 can be suitably used for producing energy carriers for transporting and storing renewable energy.

[0110] The embodiments of the present invention have been described in detail above. The embodiments described above are merely examples of how to implement the present invention. The content of the embodiments does not limit the technical scope of the present invention, and many design changes, such as changes, additions, and deletions of components, are possible as long as they do not depart from the spirit of the invention as defined in the claims. The new embodiments to which design changes have been made combine the effects of the respective embodiments and modifications. In the embodiments described above, the content in which such design changes are possible is emphasized with notations such as "in this embodiment" or "in this embodiment," but design changes are also permitted even if there are no such notations. Any combination of the above components is also valid as an embodiment of the present invention.

[0111] This embodiment will be described in detail below with reference to examples, but this embodiment is not limited in any way to these examples.

[0112] A simulation evaluation is performed on the cathode diffusion layer in an electrolytic device according to one embodiment of this disclosure. Figure 4 is a schematic diagram showing an example of an analysis image of the simulation evaluation. As shown in Figure 4, in a cathode 14 having a cathode catalyst layer 16 and a cathode diffusion layer 18, oil and hydrogen are flowed into the cathode diffusion layer 18, and the movement of hydrogen inside the cathode diffusion layer 18 is evaluated. The oil flows into the cathode diffusion layer 18 from an inlet 19 set on the upstream side, and the hydrogen flows into the cathode diffusion layer 18 from an inlet 19 set on the upstream side and the cathode catalyst layer 16. The movement of hydrogen is evaluated by assessing the average hydrogen concentration present near the cathode catalyst layer 16 (40 μm) and the average hydrogen concentration present throughout the cathode 14 0.08 to 0.1 seconds after the start of the analysis.

[0113] The analysis conditions for the simulation evaluation were: oil inflow rate per inlet area = 1.11 × cm ３ / s / cm ２ The hydrogen inflow rate per inlet area is 2.36 cm³. ３ / s / cm ２ Therefore, the hydrogen inflow rate per electrode area is 7.09 × 10⁻⁶. －３ cm ３ / s / cm ２ Let's assume that.

[0114] (Example 1) Figure 5 is a schematic diagram showing an example of a cross-section of the cathode 14 in Example 1. In Example 1, a cathode 14 having a cathode diffusion layer 18 in which the pore diameter of the first stage 18a is 54 μm and the pore diameter of the second stage 18b is 108 μm is used to perform a simulation evaluation of the hydrogen flow. The results are shown in Table 1.

[0115] (Comparative Example 1) Figure 6 is a schematic diagram showing an example of a cross-section of the cathode 14 in Comparative Example 1. In Comparative Example 1, a simulation evaluation is performed using a cathode having a cathode diffusion layer 18 in which all pore sizes are 54 μm. The results are shown in Table 1.

[0116] (Example 2) Figure 7 is a schematic diagram showing an example of a cross-section of the cathode 14 in Example 2. In Example 2, a cathode 14 having a cathode diffusion layer 18 in which the pore diameter of the first stage 18a is 54 μm, the pore diameter of the second stage 18b is 162 μm, and the pore diameter of the third stage 18c is 54 μm is used to perform a simulation evaluation of the hydrogen flow. The results are shown in Table 1.

[0117] (Example 3) Figure 8 is a schematic diagram showing an example of a cross-section of the cathode 14 in Example 3. In Example 3, a cathode 14 having a cathode diffusion layer 18 in which the pore diameter of the first stage 18a is 54 μm and the pore diameter of the second stage 18b is 216 μm is used to perform a simulation evaluation of the hydrogen flow. The results are shown in Table 1.

[0118]

[0119] This embodiment may be specified by the following items: [Item 1] An electrochemical apparatus comprising: an electrolyte membrane; a cathode catalyst layer disposed on one side of the electrolyte membrane; and a cathode diffusion layer disposed so as to sandwich the cathode catalyst layer between the electrolyte membrane, wherein the pore diameter or porosity differs in the thickness direction of the cathode diffusion layer. [Item 2] The electrochemical apparatus according to Item 1, further comprising: an end plate disposed so as to sandwich the cathode diffusion layer between the cathode catalyst layer, wherein the cathode diffusion layer has a plurality of stages with different pore diameters in the thickness direction of the cathode diffusion layer, the plurality of stages at least include a first stage disposed closest to the cathode catalyst layer and a second stage disposed next to the first stage near the cathode catalyst layer, wherein in the thickness direction of the cathode diffusion layer, the pore diameter increases from the cathode catalyst layer toward the end plate in the first and second stages. [Item 3] The electrochemical apparatus according to Item 2, wherein the cathode diffusion layer has a plurality of stages with different pore diameters in the thickness direction of the cathode diffusion layer, and the plurality of stages include at least a first stage located closest to the cathode catalyst layer and a second stage located next to the first stage and close to the cathode catalyst layer, and the pore diameter of the second stage is 1.1 to 300 times that of the pore diameter of the first stage. [Item 4] The electrochemical apparatus according to Item 3, wherein the pore diameter of the first stage is 1 μm to 250 μm. [Item 5] The electrochemical apparatus according to Item 3, wherein the pore diameter of the second stage is 2 μm to 299 μm. [Item 6] The electrochemical apparatus according to Item 1, further comprising an end plate arranged to sandwich the cathode diffusion layer between the cathode catalyst layer, wherein in the thickness direction of the cathode diffusion layer, the pore diameter decreases from the cathode catalyst layer toward the end plate. [Item 7] The electrochemical apparatus according to Item 1, wherein the pore size of the cathode diffusion layer has a gradient structure in the thickness direction of the cathode diffusion layer. [Item 8] The electrochemical apparatus according to Item 1, wherein the cathode diffusion layer includes a porous body made of carbon. [Item 9] The electrochemical apparatus according to Item 8, wherein the width of the carbon fibers in the carbon paper is 1 μm to 50 μm.[Item 10] The electrochemical apparatus according to Item 8, wherein the carbon paper comprises graphite. [Item 11] An electrochemical manufacturing method using an electrochemical apparatus comprising an electrolyte membrane, a cathode catalyst layer disposed on one side of the electrolyte membrane, a cathode diffusion layer disposed so as to sandwich the cathode catalyst layer between the electrolyte membrane and the cathode catalyst layer, wherein the pore size or porosity differs in the thickness direction of the cathode diffusion layer, wherein the electrolyte membrane moves protons, the cathode catalyst layer hydrogenates the hydride with the protons and electrons moving from the end plate side, and the cathode diffusion layer diffuses the hydride. [Item 12] A control device for controlling an electrochemical apparatus comprising an electrolyte membrane, a cathode catalyst layer disposed on one side of the electrolyte membrane and a cathode diffusion layer disposed so as to sandwich the cathode catalyst layer between the electrolyte membrane and the cathode diffusion layer, wherein the pore size or porosity differs in the thickness direction of the cathode diffusion layer. [Item 13] The current applied to the electrolytic cell of the electrochemical apparatus is 0.01 A / cm. ２ ~4.0 A / cm ２ A control device according to item 12, which controls the power supply of the electrochemical apparatus to such an extent. [Item 14] The flow rate of the hydride in the cathode diffusion layer of the electrochemical apparatus is 0.2 mL / min / cm² per electrode area. ２ ~3.0mL / min / cm ２ The control device described in item 12 controls the cathode liquid supply device of the electrochemical apparatus to such an extent.

[0120] This application claims priority based on Japanese Patent Application No. 2024-193237, filed with the Japan Patent Office on November 1, 2024, and incorporates all the contents of the said application.

[0121] 1 Electrolyzer 2 Electrolytic cell 3 Organic hydride production system 4 Power supply 8 Cathode liquid supply device 10 Control device 12 Anode 14 Cathode 16 Cathode catalyst layer 18 Cathode diffusion layer 20 Electrolyte membrane 22a, 22b End plate 24 Anode catalyst layer 27 Anode diffusion layer

Claims

1. An electrochemical apparatus comprising: an electrolyte membrane; a cathode catalyst layer disposed on one side of the electrolyte membrane; and a cathode diffusion layer disposed so as to sandwich the cathode catalyst layer between the electrolyte membrane, wherein the pore size or porosity differs in the thickness direction of the cathode diffusion layer.

2. The electrochemical apparatus according to claim 1, further comprising an end plate disposed to sandwich the cathode diffusion layer between the cathode catalyst layer, wherein the cathode diffusion layer has a plurality of stages with different pore diameters in the thickness direction of the cathode diffusion layer, the plurality of stages at least include a first stage located closest to the cathode catalyst layer and a second stage located next to the first stage and close to the cathode catalyst layer, and in the thickness direction of the cathode diffusion layer, the pore diameter or porosity increases from the cathode catalyst layer toward the end plate in the first and second stages.

3. The electrochemical apparatus according to claim 2, wherein the cathode diffusion layer has a plurality of stages with different pore diameters in the thickness direction of the cathode diffusion layer, and the plurality of stages include at least a first stage located closest to the cathode catalyst layer and a second stage located next to the first stage and close to the cathode catalyst layer, and the pore diameter of the second stage is 1.1 to 300 times that of the pore diameter of the first stage.

4. The electrochemical apparatus according to claim 3, wherein the pore size of the first stage is 1 μm to 250 μm.

5. The electrochemical apparatus according to claim 3, wherein the pore size of the second stage is 2 μm to 299 μm.

6. The electrochemical apparatus according to claim 1, further comprising an end plate disposed so as to sandwich the cathode diffusion layer between the cathode catalyst layer, wherein the pore diameter of the cathode diffusion layer decreases in the thickness direction from the cathode catalyst layer toward the end plate.

7. The electrochemical apparatus according to claim 1, wherein the pore size of the cathode diffusion layer has a gradient structure in the thickness direction of the cathode diffusion layer.

8. The electrochemical apparatus according to claim 1, wherein the cathode diffusion layer includes a porous body made of carbon.

9. The electrochemical apparatus according to claim 8, wherein the width of the carbon fibers in the porous body using carbon is 1 μm to 50 μm.

10. The electrochemical apparatus according to claim 8, wherein the porous body using carbon includes graphite.

11. An electrochemical manufacturing method using an electrochemical apparatus comprising an electrolyte membrane, a cathode catalyst layer disposed on one side of the electrolyte membrane, a cathode diffusion layer disposed so as to sandwich the cathode catalyst layer between the electrolyte membrane and the cathode catalyst layer, wherein the pore size or porosity differs in the thickness direction of the cathode diffusion layer, wherein the electrolyte membrane moves protons, the cathode catalyst layer hydrogenates the hydride with the protons and electrons moving from the end plate side, and the cathode diffusion layer diffuses the hydride.

12. A control device for controlling an electrochemical apparatus, comprising an electrolyte membrane, a cathode catalyst layer disposed on one side of the electrolyte membrane, and a cathode diffusion layer disposed so as to sandwich the cathode catalyst layer between the electrolyte membrane, wherein the pore size or porosity differs in the thickness direction of the cathode diffusion layer.

13. The current applied to the electrolytic cell of the electrochemical apparatus is 0.01 A / cm². ２ ~4.0 A / cm ２ The control device according to claim 12, which controls the power supply of the electrochemical apparatus to such an extent.

14. The flow rate of the hydride in the cathode diffusion layer of the electrochemical apparatus is 0.2 mL / min / cm² per electrode area. ２ ~3.0mL / min / cm ２ The control device according to claim 12, which controls the cathode liquid supply device of the electrochemical apparatus to such an extent.

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