WO2023026926A1 - Water electrolysis device, and method for controlling water electrolysis cell - Google Patents

Water electrolysis device, and method for controlling water electrolysis cell Download PDF

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WO2023026926A1
WO2023026926A1 PCT/JP2022/031094 JP2022031094W WO2023026926A1 WO 2023026926 A1 WO2023026926 A1 WO 2023026926A1 JP 2022031094 W JP2022031094 W JP 2022031094W WO 2023026926 A1 WO2023026926 A1 WO 2023026926A1
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potential
water
anode electrode
water electrolysis
mode
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PCT/JP2022/031094
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French (fr)
Japanese (ja)
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洋二 中森
温 松永
典裕 吉永
博俊 村山
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株式会社 東芝
東芝エネルギーシステムズ株式会社
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Publication of WO2023026926A1 publication Critical patent/WO2023026926A1/en

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • C25B1/04—Hydrogen or oxygen by electrolysis of water
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
    • C25B11/03—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form perforated or foraminous
    • C25B11/031—Porous electrodes
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/052—Electrodes comprising one or more electrocatalytic coatings on a substrate
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
    • C25B11/075—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound
    • C25B11/081—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound the element being a noble metal
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C25B15/02—Process control or regulation
    • C25B15/023—Measuring, analysing or testing during electrolytic production
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Definitions

  • Embodiments of the present invention relate to a water electrolysis device and a method of controlling a water electrolysis cell.
  • a water electrolysis device is a device that generates hydrogen and oxygen. During operation, a direct current is applied from the outside to the water electrolysis cell provided in the water electrolyzer, and water is electrolyzed to generate hydrogen from the cathode electrode and oxygen from the anode electrode.
  • Water electrolysis cells include solid polymer type water electrolysis cells (PEM water electrolysis cells) using a solid polymer electrolyte membrane as a diaphragm, alkaline water electrolysis cells with a diaphragm in an alkaline electrolyte, and solid oxides.
  • a solid oxide water electrolysis cell used as an electrolyte can be mentioned. Among them, the solid polymer type water electrolysis cell has a low operating temperature and is capable of producing hydrogen of high purity.
  • the problem to be solved by the invention is to provide a water electrolysis device and a water electrolysis cell control method that can suppress the elution of the metal catalyst from the anode electrode.
  • the water electrolysis device includes a water electrolysis cell, a power supply section, and a control section.
  • a water electrolysis cell uses a solid polymer electrolyte membrane with an anode electrode on one side and a cathode electrode on the other side to electrolyze water supplied to the anode electrode to generate hydrogen and oxygen. do.
  • the power supply can change the potential of the anode electrode.
  • the control unit controls the power supply unit so that the potential of the anode electrode is equal to or higher than the first potential, and in the second mode, the potential of the anode electrode is lower than the first potential and the anode electrode
  • the state of the water electrolysis cell is controlled so that the elution potential of the metal catalyst is equal to or higher than the predetermined elution potential of the metal catalyst.
  • FIG. 2 is a block diagram showing a configuration example of a power supply unit;
  • FIG. 2 is a block diagram showing a configuration example of a control unit;
  • FIG. 4 is a diagram schematically showing a reaction between an anode electrode and a cathode electrode;
  • the figure which shows the control example of a control part is provided.
  • FIG. 4 is a flow chart showing an example of control of a water electrolysis cell by a control unit;
  • the block diagram which shows the structure of the water electrolysis apparatus which concerns on 2nd Embodiment.
  • the block diagram which shows the structure of the control part which concerns on 2nd Embodiment.
  • the block diagram which shows the structure of the water electrolysis apparatus which concerns on 3rd Embodiment.
  • the block diagram which shows the structure of the control part which concerns on 3rd Embodiment.
  • FIG. 1 is a block diagram showing the configuration of a water electrolysis device 10a according to the first embodiment.
  • the water electrolysis device 10a according to this embodiment is an example of a water electrolysis device that generates hydrogen and oxygen using a solid polymer electrolyte membrane.
  • the water electrolysis device 10a includes a water electrolysis cell 20a, a first water inlet manifold 21, a second water outlet manifold 22, a gas-liquid separator 23, a first circulation pump 24, a water tank 26, and a hydrogen manifold 27. , a hydrogen gas-liquid separator 28 , a dehumidifier 29 , a power supply section 30 and a control section 40 .
  • FIG. 2 is a diagram showing a configuration example of a single cell 100a that constitutes the water electrolysis cell 20a.
  • the unit cell 100a includes a polymer electrolyte membrane (PEM) electrolyte membrane 101, an anode electrode 102, a cathode electrode 104, an anode current collector 106, and a cathode current collector 108.
  • PEM polymer electrolyte membrane
  • the water electrolysis cell 20a is configured by stacking a plurality of unit cells 100a.
  • the water electrolysis cell 20a according to the present embodiment is configured by stacking a plurality of unit cells 100a in series, it is not limited to this.
  • the water electrolysis cell 20a may be composed of a single cell 100a.
  • a plurality of single cells 100a may be connected in parallel to form the water electrolysis cell 20a.
  • the solid polymer electrolyte membrane 101 contains, for example, a fluoropolymer having a sulfonic acid group.
  • the anode electrode 102 is composed of, for example, an iridium oxide catalyst (IrOx) supported on a titanium nonwoven fabric.
  • the cathode electrode 104 is formed by coating carbon paper, carbon cloth, carbon non-woven fabric, or titanium non-woven fabric with, for example, a mixture of a platinum-supported carbon catalyst or a platinum-alloy-supported carbon catalyst and an ionomer.
  • the anode current collector 106 is connected to the anode of the power supply section 30 and the cathode current collector 108 is connected to the cathode of the power supply section 30 .
  • hydrogen ions move in the solid polymer electrolyte membrane 101, and the water H 2 O supplied from the supply section G2 is electrolyzed.
  • a reaction of 2H 2 O ⁇ 4H + +4e ⁇ +O 2 occurs at the anode electrode 102, and oxygen O 2 and unreacted water H 2 O are discharged from the discharge portion G4.
  • the first water inlet manifold 21 communicates between the gas-liquid separator 23 and the supply section G2 of each unit cell 100a. Thereby, the first water inlet manifold 21 supplies the water supplied from the gas-liquid separator 23 to the supply part G2 of each unit cell 100a.
  • the second water outlet manifold 22 communicates the gas-liquid separator 23 with the discharge section G4 of each unit cell 100a. Thereby, the second water outlet manifold 22 supplies the gas-liquid separator 23 with oxygen-containing water discharged from the discharge part G4 of each unit cell 100a.
  • the gas-liquid separator 23 recovers oxygen-containing water discharged from the discharge part G4 of each unit cell 100a, and separates oxygen and water.
  • the first circulation pump 24 supplies oxygen-containing water discharged from the discharge portion G4 of each unit cell 100a to the gas-liquid separator 23 via the second water outlet manifold 22 . Further, the first circulation pump 24 supplies the oxygen-separated water supplied from the gas-liquid separator 23 to the supply section G2 of each single cell 100a via the first water inlet manifold 21 .
  • a water tank 26 is further connected to the gas-liquid separator 23 via a pump 25 .
  • the water tank 26 temporarily stores pure water supplied from the outside.
  • the pump 25 supplies pure water from the water tank 26 to the gas-liquid separator 23 during operation of the water electrolysis device 10a.
  • the hydrogen manifold 27 communicates the hydrogen gas-liquid separator 28 with the discharge section G6 of each unit cell 100a. As a result, the hydrogen manifold 27 supplies the hydrogen gas-liquid separator 28 with the hydrogen gas and water discharged from the discharge section G6 of each unit cell 100a.
  • the hydrogen gas-liquid separator 28 separates hydrogen gas and water. Hydrogen gas-liquid separator 28 is further connected to dehumidifier 29 .
  • the dehumidifier 29 can remove water vapor, which is an impurity, from the hydrogen gas discharged from the hydrogen gas-liquid separator 28.
  • the hydrogen gas from which water vapor has been removed by the dehumidifier 29 is supplied to a hydrogen consuming device represented by, for example, a fuel cell.
  • FIG. 3 is a block diagram showing a configuration example of the power supply unit 30.
  • the power supply unit 30 has a DC power supply 30a capable of varying the supply voltage, a plurality of switches T10, T12, T14, and a voltmeter V10.
  • the anode of DC power supply 30a is connected to anode current collector 106, and the cathode is connected to cathode current collector 108 via switch T10.
  • the cathode of the DC power supply 30a can be connected to the ground potential via the switch T12.
  • cathode current collector 108 can also be connected to ground potential via switch T14.
  • the DC power supply 30a and the plurality of switches T10, T12, T14 are controlled by the control unit 40.
  • the value obtained by dividing the potential of the voltmeter V10 by the number of single cells 100a is the anode current collector 106 and the cathode current collector 108 of the single cells 100a. potential between
  • FIG. 4 is a block diagram showing a configuration example of the control unit 40.
  • the control unit 40 controls the entire water electrolysis device 10a, and has, for example, a storage unit 400, an acquisition unit 402, a connection control unit 404, and a voltage control unit 406.
  • the control unit 40 includes, for example, a CPU (Central Processing Unit) and an MPU (MicroProcessor), and configures each processing unit by executing a control program stored in the storage unit 400 .
  • each processing unit may be configured by an electronic circuit.
  • control unit 40 The specific configuration of the control unit 40 is not limited, and devices such as FPGA (Field Programmable Gate Array) and other ASIC (Application Specific Integrated Circuit) may be used. Alternatively, the control unit 40 may be configured by a general-purpose computer or the like.
  • FPGA Field Programmable Gate Array
  • ASIC Application Specific Integrated Circuit
  • the storage unit 400 is composed of, for example, an HDD (hard disk drive) or an SSD (solid state drive).
  • the storage unit 400 stores, as described above, a control program, a table L10 (see FIG. 5) showing the relationship between the pH of various metals, which will be described later with reference to FIG. 5, and the elution potential.
  • the acquisition unit 402 acquires information regarding control of the water electrolysis device 10a. In this embodiment, for example, at least information about the voltage of the voltmeter V10 (see FIG. 3) is acquired.
  • connection control unit 404 controls the connection states of the plurality of switches T10, T12, T14. Further, the voltage control unit 406 controls the voltage of the DC power supply 30a, and controls the potential applied to the anode current collector 106 of the single cell 100a (see FIG. 2). Thus, the DC power supply 30 a can change the potential applied to the anode current collector 106 under the control of the voltage control section 406 .
  • FIG. 5 is a diagram showing a control example of the control unit 40 as a comparative example.
  • the figure on the left shows the thermodynamic stability of iridium oxide.
  • the vertical axis indicates the hydrogen-based potential of the anode current collector 106
  • the horizontal axis indicates pH (PH), which is the hydrogen ion concentration of the anode electrode 102 .
  • a line L10 shows a numerical example of a table showing the relationship between the pH of iridium oxide and the elution potential. As described above, this numerical example is stored in storage unit 400 .
  • 0 volt based on hydrogen in the present embodiment means a potential at which the separation and synthesis of hydrogen molecules and hydrogen ions are in an equilibrium state. Therefore, in the present embodiment, the term "potential with respect to hydrogen” means the potential with respect to 0 volt at which the separation and synthesis of hydrogen molecules and hydrogen ions are in equilibrium.
  • the first mode is a state in which the potential of the anode electrode 102 of the single cell 100a is controlled to be equal to or higher than the first potential with respect to the hydrogen standard for the purpose of hydrogen generation. called.
  • the first potential is 1.8 volts relative to hydrogen.
  • the hydrogen-based potential of the anode electrode 102 of the unit cell 100a is approximately the same as the potential between the anode current collector 106 and the cathode current collector 108. Therefore, in the first mode, 1 0.8 volts is applied between the anode current collector 106 and the cathode current collector 108 of the single cell 100a.
  • connection control unit 404 brings the switch T10 into a conductive state and brings the switches T12 and T14 into a non-conductive state.
  • the voltage control unit 406 controls the voltage of the DC power supply 30a so that the potential between the anode current collector 106 and the cathode current collector 108 of the single cell 100a is, for example, 1.8 volts.
  • FIG. 6 is a diagram schematically showing reactions between the anode electrode 102 and the cathode electrode 104 in the state St10 of the first mode (operation mode). During operation (St10), as described above, the reaction 2H 2 O ⁇ 2H 2 +O 2 occurs within the single cell 100a.
  • the voltage control unit 406 controls the potential applied between the anode current collector 106 and the cathode current collector 108 of the single cell 100a to be zero. , to control the voltage of the DC power supply 30a.
  • FIG. 7 is a diagram schematically showing the reaction between the anode electrode 102 and the cathode electrode 104 at the time of stop (St12).
  • a so-called fuel cell reaction occurs, and a reaction of O 2 +4H + +4e ⁇ ⁇ 2H 2 O occurs at the anode electrode 102 .
  • a reaction of 2H 2 ⁇ 4H + +4e ⁇ occurs at the cathode electrode 104.
  • FIG. 8 is a diagram schematically showing the reaction between the anode electrode 102 and the cathode electrode 104 when hydrogen leaks (St14) after a lapse of time from the stop (St12).
  • the oxygen in the anode electrode 102 is gradually consumed, and hydrogen remains, so that the potential of the anode electrode 102 drops to 0V.
  • pH 0 pH 0
  • iridium oxide is reduced to iridium below 1 volt.
  • the switch T10 is disconnected, hydrogen is supplied through the solid polymer electrolyte membrane 101, so the potential of the anode electrode 102 drops to 0V.
  • iridium is oxidized.
  • the elution of iridium progresses, the performance of the anode catalyst of the anode electrode 102 deteriorates, and the performance of the water electrolysis cell 20a deteriorates.
  • FIG. 9 is a diagram showing a control example of the control unit 40 according to this embodiment.
  • the figure on the left shows the thermodynamic stability of iridium oxide.
  • the vertical axis indicates the potential of the anode current collector 106 and the horizontal axis indicates pH (PH), which is the hydrogen ion concentration of the anode electrode 102 .
  • the second mode is a state in which the potential of the anode electrode 102 is controlled to be lower than the first potential relative to hydrogen and equal to or higher than the elution potential of a predetermined metal.
  • the second mode is to make the potential of the anode electrode 102 lower than the first voltage based on hydrogen and, for example, equal to or higher than the elution potential of iridium oxide, and the generation of hydrogen stops. It is in a state where
  • the control unit 40 controls the water electrolysis cell 20a in the state St10 of the first mode (operation mode), and then controls the state St16 of the second mode (stop mode).
  • the potential between the anode current collector 106 and the cathode current collector 108 is comparable to that of hydrogen. Therefore, in the second mode (stop mode), the connection control unit 404 brings the switch T10 into a conducting state and maintains the switches T12 and T14 into a non-conducting state so that the anode current collector 106 of the unit cell 100a and the cathode A second potential may be applied across the current collector 108 .
  • FIG. 10 is a flowchart showing an example of control of the water electrolysis cell 20a by the controller 40 according to this embodiment.
  • the control unit 40 controls the first circulation pump 24 to supply oxygen-separated water supplied from the gas-liquid separator 23 through the first water inlet manifold 21 to each It is supplied to the supply section G2 of the single cell 100a.
  • the connection control unit 404 brings the switch T10 into a conducting state and brings the switches T12 and T14 into a non-conducting state.
  • the voltage control unit 406 controls the voltage of the DC power supply 30a so that the potential between the anode current collector 106 and the cathode current collector 108 of the single cell 100a becomes, for example, 1.8 volts. 1 mode is started (step S100).
  • control unit 40 determines whether or not to stop the first mode (step S102), and if it is not determined to stop (NO in step S102), the control unit 40 repeats the processing from step S100.
  • the voltage control unit 406 causes the potential of the anode current collector 106 of the single cell 100a to be equal to or higher than the elution potential, for example, the hydrogen-based potential is equal to or higher than 1.0 V. , the voltage of the DC power supply 30a is controlled. Subsequently, the controller 40 stops the first circulation pump 24 and starts the second mode (step S104).
  • control unit 40 determines whether or not to stop the operation (step S106), and if it determines to stop the operation (YES in step S106), it stops the operation. On the other hand, if it is determined not to stop the operation (NO in step S106), it is determined whether or not to resume the first mode (step S102), and if it is determined to resume the first mode (YES in step S108). , the processing from step S100 is repeated. On the other hand, if it is determined not to restart the first mode (NO in step S108), the process from step S104 is repeated.
  • the power supply unit 30 in the first mode, is controlled so that the potential of the anode electrode 102 becomes equal to or higher than the first potential (for example, 1.8 volts) relative to the hydrogen standard.
  • the potential of the anode electrode 102 is lower than the first potential (eg, 1.8 volts) relative to the hydrogen reference and is equal to or higher than the elution potential of iridium (eg, 1.0 volts).
  • the state of the water electrolysis cell 20a is controlled as follows.
  • the water electrolysis apparatus 10b In the second mode, the water electrolysis apparatus 10b according to the second embodiment controls the potential of the anode electrode 102 to be equal to or higher than the elution potential of iridium by supplying an inert gas to the cathode electrode 104. It differs from the first embodiment. Differences from the water electrolysis device 10a according to the first embodiment will be described below.
  • FIG. 11 is a block diagram showing the configuration of a water electrolysis device 10b according to the second embodiment. As shown in FIG. 11, the water electrolysis device 10b according to this embodiment further includes an inert gas supply unit 50. As shown in FIG. 11, the water electrolysis device 10b according to this embodiment further includes an inert gas supply unit 50. As shown in FIG. 11, the water electrolysis device 10b according to this embodiment further includes an inert gas supply unit 50. As shown in FIG.
  • the inert gas supply unit 50 supplies inert gas under the control of the control unit 40 .
  • the inert gas supply unit 50 is, for example, a nitrogen cylinder. In this case nitrogen is supplied as inert gas.
  • the inert gas is not limited to nitrogen and may be other inert gases such as argon.
  • the inert gas manifold 52 communicates the cathode electrode 104 of each unit cell 100a (see FIG. 2) and the inert gas supply section 50. Thereby, the inert gas supply unit 50 supplies the inert gas to the cathode electrode 104 of each unit cell 100a (see FIG. 2) through the inert gas manifold 52. As shown in FIG.
  • FIG. 12 is a block diagram showing the configuration of the control unit 40 according to the second embodiment. As shown in FIG. 12, the controller 40 according to this embodiment further includes a gas controller 408 .
  • FIG. 13 is a diagram showing a control example of the control unit 40 according to the second embodiment.
  • the vertical axis indicates the potential relative to hydrogen, and the horizontal axis indicates time.
  • the control unit 40 performs the control in the second mode for a period of time T12 after performing the control in the first mode for a period of time T10.
  • the gas control section 408 performs control to stop the supply of the inert gas from the inert gas supply section 50 .
  • control is performed to supply the inert gas from the inert gas supply unit 50 to the cathode electrode 104 of each single cell 100a (see FIG. 2).
  • the potential L12 of the cathode electrode 104 starts rising and stabilizes at about 1 volt.
  • the potential L14 of the anode electrode 102 begins to decrease when the second mode is started, and stops decreasing when it reaches the same potential as that of the cathode electrode 104.
  • a DC potential from the DC power supply 30a may be applied in the second mode.
  • a potential difference of 1 volt may be applied to the cathode electrode 104 from the DC power supply 30a.
  • the connection control unit 404 turns on the switch T10 and turns off the switches T12 and T14 so that the second potential is applied between the anode current collector 106 and the cathode current collector 108 of the single cell 100a. may be printed.
  • the potential increase of the cathode electrode 104 by the inert gas is 0.8 volts, 0.2 volts or more is applied to the cathode electrode 104 from the DC power source 30a.
  • the potential L14 of the anode electrode 102 is stabilized at 1 volt based on hydrogen.
  • the potential of the cathode electrode 104 is 0 volts as described above.
  • the potential L16 of the anode electrode 102 begins to decrease due to hydrogen leaking from the cathode electrode 104 through the solid polymer electrolyte membrane 101 to the anode electrode 102, and to 0 volts, which is the same potential as .
  • the gas control unit 408 starts supplying the inert gas from the inert gas supply unit 50 at the start of the second mode.
  • the potential of the cathode electrode 104 can be increased to 1 volt or more based on hydrogen. Therefore, the potential L14 of the anode electrode 102 is controlled to be equal to or higher than the elution potential of iridium even when the second mode is started. This makes it possible to suppress the oxidation-reduction reaction of iridium oxide, which is the metal catalyst of the anode electrode 102, and suppress the elution of iridium.
  • the water electrolysis apparatus 10c controls the potential of the anode electrode 102 to be equal to or higher than the elution potential of iridium by infiltrating the cathode electrode 104 with water in the second mode. It differs from the embodiment. Differences from the water electrolysis device 10a according to the first embodiment will be described below.
  • FIG. 14 is a block diagram showing the configuration of a water electrolysis device 10c according to the third embodiment.
  • the water electrolysis device 10c according to this embodiment further includes a water supply section 60.
  • the water supply section 60 has a second circulation pump 63 and a second water tank 64 .
  • the second water tank 64 is provided vertically above the water electrolysis cell 20a.
  • FIG. 15 is a diagram showing a configuration example of a unit cell 100b according to the third embodiment.
  • the cathode current collector 108 is arranged on the first surface of the cathode electrode 104, and the water flow path 110 is formed on the second surface facing the first surface.
  • the cathode current collector 108 is made of a carbon or metal porous material. Water is supplied from the supply portion G8 of the water channel 110 and discharged from the discharge portion G10.
  • each unit cell 100b and the second water tank 64 are in communication via the second water inlet manifold 61.
  • the outlet G10 of each unit cell 100b and the second circulation pump 63 are in communication via the second water outlet manifold 62.
  • the water electrolysis cell 20b is configured by stacking each unit cell 100b.
  • FIG. 16 is a block diagram showing the configuration of the control unit 40 according to the third embodiment. As shown in FIG. 16 , the control section 40 according to this embodiment further includes a water control section 410 .
  • FIG. 17 is a diagram showing a control example of the control unit 40 according to the third embodiment.
  • the vertical axis indicates the potential relative to hydrogen, and the horizontal axis indicates time.
  • the control unit 40 performs control in the second mode for time T16 after performing control in the first mode for time T14.
  • part of the water in the anode electrode 102 moves to the cathode electrode 104 side through the solid polymer electrolyte membrane 100 .
  • the water control section 410 drives the second circulation pump 63 to suck water through the second water outlet manifold 62 .
  • the water in the second water tank 64 is supplied to the water flow path 110 via the second water inlet manifold 61 .
  • the water flow path 110 is sucked by the second circulation pump 63 so that the pressure inside the cathode electrode 104 becomes negative. Therefore, the water that has moved to the cathode electrode 104 side moves to the water flow path 110 via the cathode current collector 108 because the cathode current collector 108 is porous.
  • the hydrogen gas-liquid separation process becomes possible, and the size of the hydrogen gas-liquid separator 28 can be reduced.
  • the water control section 410 stops the second circulation pump 63 .
  • the water in the second water tank 64 becomes positive pressure due to gravity
  • the water in the water flow path 110 moves to the cathode electrode 104 via the cathode current collector 108, and hydrogen is discharged to the outside of the cathode electrode.
  • the potential L18 of the cathode electrode 104 starts rising and stabilizes at about 1 volt.
  • the potential L20 of the anode electrode 102 starts decreasing when the second mode is started, and stops decreasing when it becomes the same potential as that of the cathode electrode 104 .
  • the potential L16 of the anode electrode 102 is an example when the cathode electrode 104 is not purged with water.
  • a DC potential from the DC power supply 30a may be applied in the second mode. For example, if the potential rise of the cathode electrode 104 due to the water purge does not reach 1 volt, a potential difference of 1 volt may be applied to the cathode electrode 104 from the DC power supply 30a.
  • the connection control unit 404 turns on the switch T10 and turns off the switches T12 and T14 so that the second potential is applied between the anode current collector 106 and the cathode current collector 108 of the single cell 100a. may be printed.
  • the potential increase of the cathode electrode 104 by the inert gas is 0.8 volts
  • 0.2 volts is applied to the cathode electrode 104 from the DC power source 30a.
  • the potential L14 of the anode electrode 102 is stabilized at 1 volt based on hydrogen.
  • the water control unit 410 starts supplying water from the inside of the second water tank 64 under positive pressure in time with the start of the second mode.
  • the water in the water channel 110 moves to the cathode electrode 104 through the cathode current collector 108, the hydrogen is discharged to the outside of the cathode electrode, and the potential L18 of the cathode electrode 104 stabilizes at about 1 volt. .
  • the potential L20 of the anode electrode 102 is controlled to be equal to or higher than the elution potential of iridium even when the second mode is started. This makes it possible to suppress the oxidation-reduction reaction of iridium oxide, which is the metal catalyst of the anode electrode 102, and suppress the elution of iridium.

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Abstract

According to this embodiment, a water electrolysis device comprises a water electrolysis cell, a power supply unit, and a control unit. By using a solid polymer electrolytic membrane having one surface on which an anode electrode is installed and the other surface on which a cathode electrode is installed, the water electrolysis cell electrolyzes the water supplied to the anode electrode to generate hydrogen and oxygen. The power supply unit can change the potential of the anode electrode. In a first mode, the control unit controls the power supply unit so that the potential of the anode electrode is at least a first potential. In a second mode, the control unit controls the state of the water electrolysis cell so that the potential of the anode electrode is lower than the first potential and is at least the dissolution potential of a predetermined catalyst in the anode electrode.

Description

水電解装置、及び水電解セルの制御方法Water electrolysis device and method for controlling water electrolysis cell
　本発明の実施形態は、水電解装置、及び水電解セルの制御方法に関する。 Embodiments of the present invention relate to a water electrolysis device and a method of controlling a water electrolysis cell.
　水電解装置は、水素と酸素を発生する装置である。稼働時は、水電解装置が備える水電解セルに外部から直流電流を流し、水を電気分解することによりカソード電極から水素を、アノード電極から酸素を発生する。水電解セルとしては、固体高分子形電解質膜を隔膜として使用した固体高分子形水電解セル（ＰＥＭ水電解セル）や、アルカリ電解液中に隔膜を設けたアルカリ水電解セル、固体酸化物を電解質として用いた固体酸化物形水電解セルが挙げられる。中でも固体高分子形水電解セルは作動温度が低く、且つ純度の高い水素の生成が可能である。 A water electrolysis device is a device that generates hydrogen and oxygen. During operation, a direct current is applied from the outside to the water electrolysis cell provided in the water electrolyzer, and water is electrolyzed to generate hydrogen from the cathode electrode and oxygen from the anode electrode. Water electrolysis cells include solid polymer type water electrolysis cells (PEM water electrolysis cells) using a solid polymer electrolyte membrane as a diaphragm, alkaline water electrolysis cells with a diaphragm in an alkaline electrolyte, and solid oxides. A solid oxide water electrolysis cell used as an electrolyte can be mentioned. Among them, the solid polymer type water electrolysis cell has a low operating temperature and is capable of producing hydrogen of high purity.
特開２０１９－９９９０５号公報JP 2019-99905 A
　しかしながら、稼働を停止すると、固体高分子形水電解セルにおけるアノード電極の金属触媒の酸化還元反応過程において金属が溶出することがわかってきた。このような触媒の酸化還元反応の過程において金属が溶出することにより、アノード触媒の性能が低下し、その結果として水電解セルの性能が低下する恐れがある。 However, it has been found that when the operation is stopped, the metal is eluted during the oxidation-reduction reaction process of the metal catalyst of the anode electrode in the solid polymer water electrolysis cell. The elution of metals in the course of such oxidation-reduction reactions of the catalyst may reduce the performance of the anode catalyst and, as a result, the performance of the water electrolysis cell.
　そこで、発明が解決しようとする課題は、アノード電極の金属触媒の溶出を抑制可能な水電解装置及び水電解セルの制御方法を提供することである。 Therefore, the problem to be solved by the invention is to provide a water electrolysis device and a water electrolysis cell control method that can suppress the elution of the metal catalyst from the anode electrode.
　本実施形態によれば、水電解装置は、水電解セルと、電源部と、制御部と、を備える。水電解セルは、一方の面にアノード電極を設置し、他方の面にカソード電極を設置した固体高分子電解質膜を用いてアノード電極に供給された水を電気分解して、水素と酸素を発生する。電源部は、アノード電極の電位を変更可能である。制御部は、第１モードでは、電源部を、アノード電極の電位が第１電位以上となるように制御し、第２モードでは、アノード電極の電位が第１電位よりも低く、且つ、アノード電極における所定の金属触媒の溶出電位以上となるように水電解セルの状態を制御する。 According to this embodiment, the water electrolysis device includes a water electrolysis cell, a power supply section, and a control section. A water electrolysis cell uses a solid polymer electrolyte membrane with an anode electrode on one side and a cathode electrode on the other side to electrolyze water supplied to the anode electrode to generate hydrogen and oxygen. do. The power supply can change the potential of the anode electrode. In the first mode, the control unit controls the power supply unit so that the potential of the anode electrode is equal to or higher than the first potential, and in the second mode, the potential of the anode electrode is lower than the first potential and the anode electrode The state of the water electrolysis cell is controlled so that the elution potential of the metal catalyst is equal to or higher than the predetermined elution potential of the metal catalyst.
　本発明によれば、アノード電極の金属触媒の溶出を抑制できる。 According to the present invention, elution of the metal catalyst from the anode electrode can be suppressed.
水電解装置の構成を示すブロック図。The block diagram which shows the structure of a water electrolysis apparatus. 水電解セルを構成する単セルの構成例を示す図。The figure which shows the structural example of the single cell which comprises a water electrolysis cell. 電源部の構成例を示すブロック図。FIG. 2 is a block diagram showing a configuration example of a power supply unit; 制御部の構成例を示すブロック図。FIG. 2 is a block diagram showing a configuration example of a control unit; 制御部の比較例としての制御例を示す図。The figure which shows the example of control as a comparative example of a control part. アノード電極と、カソード電極と、の反応を模式的に示す図。FIG. 4 is a diagram schematically showing a reaction between an anode electrode and a cathode electrode; 停止時における、反応を模式的に示す図。The figure which shows typically reaction at the time of a stop. 停止時から時間が２分経過した反応を模式的に示す図。The figure which shows typically the reaction which time passed for 2 minutes from the time of a stop. 制御部の制御例を示す図。The figure which shows the control example of a control part. 制御部の水電解セルに対する制御例を示すフローチャート。4 is a flow chart showing an example of control of a water electrolysis cell by a control unit; 第２実施形態に係る水電解装置の構成を示すブロック図。The block diagram which shows the structure of the water electrolysis apparatus which concerns on 2nd Embodiment. 第２実施形態に係る制御部の構成を示すブロック図。The block diagram which shows the structure of the control part which concerns on 2nd Embodiment. 第２実施形態に係る制御部の制御例を示す図。The figure which shows the example of a control of the control part which concerns on 2nd Embodiment. 第３実施形態に係る水電解装置の構成を示すブロック図。The block diagram which shows the structure of the water electrolysis apparatus which concerns on 3rd Embodiment. 第３実施形態に係る単セルの構成例を示す図。The figure which shows the structural example of the single cell which concerns on 3rd Embodiment. 第３実施形態に係る制御部の構成を示すブロック図。The block diagram which shows the structure of the control part which concerns on 3rd Embodiment. 第３実施形態に係る制御部の制御例を示す図。The figure which shows the example of a control of the control part which concerns on 3rd Embodiment.
　以下、本発明の実施形態に係る水電解装置及び水電解セルの制御方法について、図面を参照しながら詳細に説明する。なお、以下に示す実施形態は、本発明の実施形態の一例であって、本発明はこれらの実施形態に限定して解釈されるものではない。また、本実施形態で参照する図面において、同一部分又は同様な機能を有する部分には同一の符号又は類似の符号を付し、その繰り返しの説明は省略する場合がある。また、図面の寸法比率は説明の都合上実際の比率とは異なる場合や、構成の一部が図面から省略される場合がある。 Hereinafter, the water electrolysis device and the water electrolysis cell control method according to the embodiment of the present invention will be described in detail with reference to the drawings. The embodiments shown below are examples of embodiments of the present invention, and the present invention should not be construed as being limited to these embodiments. In addition, in the drawings referred to in this embodiment, the same reference numerals or similar reference numerals are given to the same portions or portions having similar functions, and repeated description thereof may be omitted. Also, the dimensional ratios in the drawings may differ from the actual ratios for convenience of explanation, and some of the configurations may be omitted from the drawings.
　（第１実施形態）　
　図１は、第１実施形態に係る水電解装置１０ａの構成を示すブロック図である。この図１に示すように、本実施形態に係る水電解装置１０ａは、固体高分子電解質膜を用いて水素と酸素を発生する水電解装置の一例である。水電解装置１０ａは、水電解セル２０ａと、第１水入口マニホールド２１と、第２水出口マニホールド２２と、気液分離機２３と、第１循環ポンプ２４と、水タンク２６と、水素マニホールド２７と、水素気液分離機２８と、除湿器２９と、電源部３０と、制御部４０とを備える。 (First embodiment)
FIG. 1 is a block diagram showing the configuration of a water electrolysis device 10a according to the first embodiment. As shown in FIG. 1, the water electrolysis device 10a according to this embodiment is an example of a water electrolysis device that generates hydrogen and oxygen using a solid polymer electrolyte membrane. The water electrolysis device 10a includes a water electrolysis cell 20a, a first water inlet manifold 21, a second water outlet manifold 22, a gas-liquid separator 23, a first circulation pump 24, a water tank 26, and a hydrogen manifold 27. , a hydrogen gas-liquid separator 28 , a dehumidifier 29 , a power supply section 30 and a control section 40 .
　図２は、水電解セル２０ａを構成する単セル１００ａの構成例を示す図である。図２に示すように、単セル１００ａは、固体高分子（ＰＥＭ：Ｐｏｌｙｍｅｒ　Ｅｌｅｃｔｒｏｌｙｔｅ　Ｍｅｍｂｒａｎｅ）電解質膜１０１と、アノード電極１０２と、カソード電極１０４と、アノード集電体１０６と、カソード集電体１０８と、を有する。単セル１００ａは、固体高分子電解質膜１０１がアノード電極１０２とカソード電極１０４とで挟持され、さらにその両外側にアノード集電体１０６及びカソード集電体１０８が配置される。そして、水電解セル２０ａは、複数の単セル１００ａを積層して構成される。なお、本実施形態に係る水電解セル２０ａは、複数の単セル１００ａを直列に積層して構成されるが、これに限定されない。例えば、水電解セル２０ａを単セル１００ａで構成してもよい。或いは、複数の単セル１００ａを並列に接続して水電解セル２０ａを構成してもよい FIG. 2 is a diagram showing a configuration example of a single cell 100a that constitutes the water electrolysis cell 20a. As shown in FIG. 2, the unit cell 100a includes a polymer electrolyte membrane (PEM) electrolyte membrane 101, an anode electrode 102, a cathode electrode 104, an anode current collector 106, and a cathode current collector 108. , has In the unit cell 100a, a solid polymer electrolyte membrane 101 is sandwiched between an anode electrode 102 and a cathode electrode 104, and an anode current collector 106 and a cathode current collector 108 are arranged on both outer sides thereof. The water electrolysis cell 20a is configured by stacking a plurality of unit cells 100a. Although the water electrolysis cell 20a according to the present embodiment is configured by stacking a plurality of unit cells 100a in series, it is not limited to this. For example, the water electrolysis cell 20a may be composed of a single cell 100a. Alternatively, a plurality of single cells 100a may be connected in parallel to form the water electrolysis cell 20a.
　固体高分子電解質膜１０１は、例えばスルホン酸基を有するフッ素系高分子を含んで構成される。アノード電極１０２は、例えば酸化イリジウム触媒（ＩｒＯｘ）がチタン不織布に担持されたもので構成されている。カソード電極１０４は、例えば白金担持カーボン触媒もしくは白金合金担持カーボン触媒とアイオノマーの混合物がカーボンペーパー、カーボンクロス、カーボン不織布もしくはチタン不織布に塗工されたもので構成されている。 The solid polymer electrolyte membrane 101 contains, for example, a fluoropolymer having a sulfonic acid group. The anode electrode 102 is composed of, for example, an iridium oxide catalyst (IrOx) supported on a titanium nonwoven fabric. The cathode electrode 104 is formed by coating carbon paper, carbon cloth, carbon non-woven fabric, or titanium non-woven fabric with, for example, a mixture of a platinum-supported carbon catalyst or a platinum-alloy-supported carbon catalyst and an ionomer.
　アノード集電体１０６は、電源部３０の陽極に接続され、カソード集電体１０８は、電源部３０の陰極に接続される。これにより、固体高分子電解質膜１０１の中で水素イオンが移動して、供給部Ｇ２から供給された水Ｈ２Ｏが電解される。このとき、アノード電極１０２では、２Ｈ２Ｏ→４Ｈ＋＋４ｅ－＋Ｏ２の反応が起き、酸素Ｏ２と未反応の水Ｈ２Ｏが排出部Ｇ４から排出される。 The anode current collector 106 is connected to the anode of the power supply section 30 and the cathode current collector 108 is connected to the cathode of the power supply section 30 . As a result, hydrogen ions move in the solid polymer electrolyte membrane 101, and the water H 2 O supplied from the supply section G2 is electrolyzed. At this time, a reaction of 2H 2 O→4H + +4e − +O 2 occurs at the anode electrode 102, and oxygen O 2 and unreacted water H 2 O are discharged from the discharge portion G4.
　一方で、カソード電極１０４では、４Ｈ＋＋４ｅ－→２Ｈ２の反応が起き、水素Ｈ２が排出部Ｇ６から排出される。このように単セル１００ａ内では、２Ｈ２Ｏ→２Ｈ２＋Ｏ２の反応が起きる。 On the other hand, at the cathode electrode 104, a reaction of 4H + +4e − →2H 2 occurs and hydrogen H 2 is discharged from the discharge portion G6. In this manner, a reaction of 2H 2 O→2H 2 +O 2 occurs within the single cell 100a.
　第１水入口マニホールド２１は、気液分離機２３と各単セル１００ａの供給部Ｇ２とを連通する。これにより、第１水入口マニホールド２１は、気液分離機２３から供給される水を各単セル１００ａの供給部Ｇ２に供給する。 The first water inlet manifold 21 communicates between the gas-liquid separator 23 and the supply section G2 of each unit cell 100a. Thereby, the first water inlet manifold 21 supplies the water supplied from the gas-liquid separator 23 to the supply part G2 of each unit cell 100a.
　第２水出口マニホールド２２は、気液分離機２３と各単セル１００ａの排出部Ｇ４とを連通する。これにより、第２水出口マニホールド２２は、各単セル１００ａの排出部Ｇ４から排出される酸素を含む水を、気液分離機２３に供給する。 The second water outlet manifold 22 communicates the gas-liquid separator 23 with the discharge section G4 of each unit cell 100a. Thereby, the second water outlet manifold 22 supplies the gas-liquid separator 23 with oxygen-containing water discharged from the discharge part G4 of each unit cell 100a.
　気液分離機２３は、各単セル１００ａの排出部Ｇ４から排出される酸素を含む水を回収し、酸素と水を分離する。第１循環ポンプ２４は、各単セル１００ａの排出部Ｇ４から排出される酸素を含む水を、第２水出口マニホールド２２を介して気液分離機２３に供給する。また、第１循環ポンプ２４は、気液分離機２３から供給される酸素を分離した水を、第１水入口マニホールド２１を介して、各単セル１００ａの供給部Ｇ２に供給する。 The gas-liquid separator 23 recovers oxygen-containing water discharged from the discharge part G4 of each unit cell 100a, and separates oxygen and water. The first circulation pump 24 supplies oxygen-containing water discharged from the discharge portion G4 of each unit cell 100a to the gas-liquid separator 23 via the second water outlet manifold 22 . Further, the first circulation pump 24 supplies the oxygen-separated water supplied from the gas-liquid separator 23 to the supply section G2 of each single cell 100a via the first water inlet manifold 21 .
　気液分離機２３には、さらにポンプ２５を介して水タンク２６が接続されている。水タンク２６は外部から供給される純水を一時的に貯蔵する。ポンプ２５は、水電解装置１０ａの運転時に、純水を水タンク２６から気液分離機２３に補給する。 A water tank 26 is further connected to the gas-liquid separator 23 via a pump 25 . The water tank 26 temporarily stores pure water supplied from the outside. The pump 25 supplies pure water from the water tank 26 to the gas-liquid separator 23 during operation of the water electrolysis device 10a.
　水素マニホールド２７は、水素気液分離機２８と各単セル１００ａの排出部Ｇ６とを連通する。これにより、水素マニホールド２７は、各単セル１００ａの排出部Ｇ６から排出される水素ガス及び水を、水素気液分離機２８に供給する。 The hydrogen manifold 27 communicates the hydrogen gas-liquid separator 28 with the discharge section G6 of each unit cell 100a. As a result, the hydrogen manifold 27 supplies the hydrogen gas-liquid separator 28 with the hydrogen gas and water discharged from the discharge section G6 of each unit cell 100a.
　水素気液分離機２８は、水素ガスと水を分離する。水素気液分離機２８は、更に除湿器２９に接続される。 The hydrogen gas-liquid separator 28 separates hydrogen gas and water. Hydrogen gas-liquid separator 28 is further connected to dehumidifier 29 .
　除湿器２９は水素気液分離機２８から排出された水素ガスから不純物である水蒸気を取り除くことが可能である。除湿器２９で水蒸気が取り除かれた水素ガスは、例えば燃料電池に代表される水素消費装置に供給される。 The dehumidifier 29 can remove water vapor, which is an impurity, from the hydrogen gas discharged from the hydrogen gas-liquid separator 28. The hydrogen gas from which water vapor has been removed by the dehumidifier 29 is supplied to a hydrogen consuming device represented by, for example, a fuel cell.
　図３は、電源部３０の構成例を示すブロック図である。図３に示すよう、電源部３０は、供給電圧を可変させることが可能な直流電源３０ａと、複数のスイッチＴ１０、Ｔ１２、Ｔ１４と、電圧計Ｖ１０とを有する。直流電源３０ａの陽極はアノード集電体１０６と接続され、陰極はカソード集電体１０８と、スイッチＴ１０を介して接続される。また、直流電源３０ａの陰極は、スイッチＴ１２を介して、接地電位に接続可能である。同様に、カソード集電体１０８もスイッチＴ１４を介して、接地電位に接続可能である。 FIG. 3 is a block diagram showing a configuration example of the power supply unit 30. As shown in FIG. As shown in FIG. 3, the power supply unit 30 has a DC power supply 30a capable of varying the supply voltage, a plurality of switches T10, T12, T14, and a voltmeter V10. The anode of DC power supply 30a is connected to anode current collector 106, and the cathode is connected to cathode current collector 108 via switch T10. Also, the cathode of the DC power supply 30a can be connected to the ground potential via the switch T12. Similarly, cathode current collector 108 can also be connected to ground potential via switch T14.
　直流電源３０ａと、複数のスイッチＴ１０、Ｔ１２、Ｔ１４とは、制御部４０に制御される。複数の単セル１００ａが直列に接続されている場合には、電圧計Ｖ１０の電位を単セル１００ａの数で除算した値が、単セル１００ａのアノード集電体１０６と、カソード集電体１０８との間の電位となる。 The DC power supply 30a and the plurality of switches T10, T12, T14 are controlled by the control unit 40. When a plurality of single cells 100a are connected in series, the value obtained by dividing the potential of the voltmeter V10 by the number of single cells 100a is the anode current collector 106 and the cathode current collector 108 of the single cells 100a. potential between
　図４は、制御部４０の構成例を示すブロック図である。図４に示すように、制御部４０は、水電解装置１０ａの全体を制御し、例えば記憶部４００と、取得部４０２と、接続制御部４０４と、電圧制御部４０６とを有する。制御部４０は、例えばＣＰＵ（ＣｅｎｔｒａｌＰｒｏｃｅｓｓｉｎｇＵｎｉｔ）やＭＰＵ（ＭｉｃｒｏＰｒｏｃｅｓｓｏｒ）を含んで構成され、記憶部４００に記憶される制御プログラムを実行することにより各処理部を構成する。なお、各処理部を電子回路で構成してもよい。 FIG. 4 is a block diagram showing a configuration example of the control unit 40. As shown in FIG. As shown in FIG. 4, the control unit 40 controls the entire water electrolysis device 10a, and has, for example, a storage unit 400, an acquisition unit 402, a connection control unit 404, and a voltage control unit 406. The control unit 40 includes, for example, a CPU (Central Processing Unit) and an MPU (MicroProcessor), and configures each processing unit by executing a control program stored in the storage unit 400 . Note that each processing unit may be configured by an electronic circuit.
　制御部４０の具体的な構成は限定されず、例えばＦＰＧＡ（Ｆｉｅｌｄ　Ｐｒｏｇｒａｍｍａｂｌｅ　Ｇａｔｅ　Ａｒｒａｙ）、その他ＡＳＩＣ（Ａｐｐｌｉｃａｔｉｏｎ　Ｓｐｅｃｉｆｉｃ　Ｉｎｔｅｇｒａｔｅｄ　Ｃｉｒｃｕｉｔ）等のデバイスが用いられてもよい。或いは、この制御部４０は、汎用のコンピュータなどにより構成してもよい。 The specific configuration of the control unit 40 is not limited, and devices such as FPGA (Field Programmable Gate Array) and other ASIC (Application Specific Integrated Circuit) may be used. Alternatively, the control unit 40 may be configured by a general-purpose computer or the like.
　記憶部４００は、例えばＨＤＤ（ハードディスクドライブ）やＳＳＤ（ソリッドステートドライブ）等で構成される。この記憶部４００は、上述のように、制御プログラムと、図５により後述する各種金属のペーハ（ＰＨ）と、溶出電位との関係を示すテーブルＬ１０（図５参照）などを記憶している。 The storage unit 400 is composed of, for example, an HDD (hard disk drive) or an SSD (solid state drive). The storage unit 400 stores, as described above, a control program, a table L10 (see FIG. 5) showing the relationship between the pH of various metals, which will be described later with reference to FIG. 5, and the elution potential.
　取得部４０２は、水電解装置１０ａの制御に関する情報を取得する。本実施形態では、例えば、電圧計Ｖ１０（図３参照）の電圧に関する情報を少なくとも取得する。 The acquisition unit 402 acquires information regarding control of the water electrolysis device 10a. In this embodiment, for example, at least information about the voltage of the voltmeter V10 (see FIG. 3) is acquired.
　接続制御部４０４は、複数のスイッチＴ１０、Ｔ１２、Ｔ１４の接続状態を制御する。また、電圧制御部４０６は、直流電源３０ａの電圧を制御し、単セル１００ａ（図２参照）のアノード集電体１０６に印可される電位を制御する。このように、直流電源３０ａは、電圧制御部４０６の制御にしたがい、アノード集電体１０６に印可する電位を変更可能である。 The connection control unit 404 controls the connection states of the plurality of switches T10, T12, T14. Further, the voltage control unit 406 controls the voltage of the DC power supply 30a, and controls the potential applied to the anode current collector 106 of the single cell 100a (see FIG. 2). Thus, the DC power supply 30 a can change the potential applied to the anode current collector 106 under the control of the voltage control section 406 .
　図５は、制御部４０の比較例としての制御例を示す図である。左図は酸化イリジウムの熱力学安定性を示す図である。縦軸は、アノード集電体１０６の水素基準における電位を示し、横軸は、アノード電極１０２の水素イオン濃度であるペ－ハー（ＰＨ）を示している。ラインＬ１０は、酸化イリジウムのペーハーと溶出電位との関係を示すテーブルの数値例を示す。上述のように、この数値例は、記憶部４００に記憶される。本実施形態における水素基準の０ボルトは、水素分子と水素イオンとの分離、合成が平衡状態である電位を意味する。このため、本実施形態において水素基準に対する電位と称する場合には、水素分子と水素イオンとの分離、合成が平衡状態である０ボルトに対する電位を意味する。 FIG. 5 is a diagram showing a control example of the control unit 40 as a comparative example. The figure on the left shows the thermodynamic stability of iridium oxide. The vertical axis indicates the hydrogen-based potential of the anode current collector 106 , and the horizontal axis indicates pH (PH), which is the hydrogen ion concentration of the anode electrode 102 . A line L10 shows a numerical example of a table showing the relationship between the pH of iridium oxide and the elution potential. As described above, this numerical example is stored in storage unit 400 . 0 volt based on hydrogen in the present embodiment means a potential at which the separation and synthesis of hydrogen molecules and hydrogen ions are in an equilibrium state. Therefore, in the present embodiment, the term "potential with respect to hydrogen" means the potential with respect to 0 volt at which the separation and synthesis of hydrogen molecules and hydrogen ions are in equilibrium.
　なお、本実施形態では、水素生成を目的として、単セル１００ａのアノード電極１０２の電位を水素基準に対して第１電位以上となるように制御している状態を第１モード（稼働モード）と称する。例えば、第１電位は、水素基準における１．８ボルトである。本実施形態では、単セル１００ａのアノード電極１０２の水素基準における電位は、アノード集電体１０６と、カソード集電体１０８との間の電位と、ほぼ同等であるので、第１モードでは、１．８ボルトを単セル１００ａのアノード集電体１０６と、カソード集電体１０８との間に印可する。 In the present embodiment, the first mode (operating mode) is a state in which the potential of the anode electrode 102 of the single cell 100a is controlled to be equal to or higher than the first potential with respect to the hydrogen standard for the purpose of hydrogen generation. called. For example, the first potential is 1.8 volts relative to hydrogen. In the present embodiment, the hydrogen-based potential of the anode electrode 102 of the unit cell 100a is approximately the same as the potential between the anode current collector 106 and the cathode current collector 108. Therefore, in the first mode, 1 0.8 volts is applied between the anode current collector 106 and the cathode current collector 108 of the single cell 100a.
　図５に示すように、第１モード（稼働モード）の状態Ｓｔ１０において、接続制御部４０４は、スイッチＴ１０を導通状態とし、スイッチＴ１２、Ｔ１４を非導通状態とする。そして、電圧制御部４０６は、単セル１００ａのアノード集電体１０６と、カソード集電体１０８との間の電位が例えば１．８ボルトになるように、直流電源３０ａの電圧を制御する。 As shown in FIG. 5, in state St10 of the first mode (operating mode), the connection control unit 404 brings the switch T10 into a conductive state and brings the switches T12 and T14 into a non-conductive state. The voltage control unit 406 controls the voltage of the DC power supply 30a so that the potential between the anode current collector 106 and the cathode current collector 108 of the single cell 100a is, for example, 1.8 volts.
　図６は、第１モード（稼働モード）の状態Ｓｔ１０における、アノード電極１０２と、カソード電極１０４と、の反応を模式的に示す図である。稼働時（Ｓｔ１０）においては、上述のように、単セル１００ａ内では、２Ｈ２Ｏ→２Ｈ２＋Ｏ２の反応が起きる。 FIG. 6 is a diagram schematically showing reactions between the anode electrode 102 and the cathode electrode 104 in the state St10 of the first mode (operation mode). During operation (St10), as described above, the reaction 2H 2 O→2H 2 +O 2 occurs within the single cell 100a.
　再び図５に示すように、停止時（Ｓｔ１２）において、電圧制御部４０６は、単セル１００ａのアノード集電体１０６と、カソード集電体１０８との間に印可する電位が０になるように、直流電源３０ａの電圧を制御する。 As shown in FIG. 5 again, at the time of stop (St12), the voltage control unit 406 controls the potential applied between the anode current collector 106 and the cathode current collector 108 of the single cell 100a to be zero. , to control the voltage of the DC power supply 30a.
　図７は、停止時（Ｓｔ１２）における、アノード電極１０２と、カソード電極１０４と、の反応を模式的に示す図である。停止時（Ｓｔ１２）においては、所謂燃料電池反応が起き、アノード電極１０２では、Ｏ２＋４Ｈ＋＋４ｅ－→２Ｈ２Ｏの反応が起きる。一方で、カソード電極１０４では、２Ｈ２→４Ｈ＋＋４ｅ－の反応が起きる。 FIG. 7 is a diagram schematically showing the reaction between the anode electrode 102 and the cathode electrode 104 at the time of stop (St12). At the time of stop (St12), a so-called fuel cell reaction occurs, and a reaction of O 2 +4H + +4e − →2H 2 O occurs at the anode electrode 102 . On the other hand, at the cathode electrode 104, a reaction of 2H 2 →4H + +4e − occurs.
　図８は、停止時（Ｓｔ１２）から時間が経過した水素リーク時（Ｓｔ１４）の、アノード電極１０２と、カソード電極１０４と、の反応を模式的に示す図である。停止時（Ｓｔ１２）から時間が経過すると、アノード電極１０２の酸素が次第に消費され、水素が余ることでアノード電極１０２の電位が０Ｖまで低下する。しかしながら、ペーハーが０（ｐＨ＝０）において酸化イリジウムは１ボルトを下回るとイリジウムに還元される。なお、スイッチＴ１０を非接続状態としても、固体高分子電解質膜１０１を介して水素は供給されるため、アノード電極１０２の電位は０Ｖまで低下する。 FIG. 8 is a diagram schematically showing the reaction between the anode electrode 102 and the cathode electrode 104 when hydrogen leaks (St14) after a lapse of time from the stop (St12). As time passes from the time of stop (St12), the oxygen in the anode electrode 102 is gradually consumed, and hydrogen remains, so that the potential of the anode electrode 102 drops to 0V. However, at pH 0 (pH=0), iridium oxide is reduced to iridium below 1 volt. Even if the switch T10 is disconnected, hydrogen is supplied through the solid polymer electrolyte membrane 101, so the potential of the anode electrode 102 drops to 0V.
　再び図５に戻り、図５の右図に示すように、水素リーク時（Ｓｔ１４）においてイリジウムに還元されたアノード電極の触媒は、稼働時（Ｓｔ１０）において再び１ボルトより電位が高くなることにより、イリジウムが酸化される。このように、アノード電極１０２における酸化イリジウムを含む触媒の酸化還元反応の繰り返しにより、イリジウムの溶出が進み、アノード電極１０２のアノード触媒の性能が低下し、水電解セル２０ａの性能が低下してしまう。 Returning to FIG. 5 again, as shown in the right figure of FIG. , iridium is oxidized. As described above, due to the repetition of the redox reaction of the catalyst containing iridium oxide in the anode electrode 102, the elution of iridium progresses, the performance of the anode catalyst of the anode electrode 102 deteriorates, and the performance of the water electrolysis cell 20a deteriorates. .
　図９は、本実施形態に係る制御部４０の制御例を示す図である。左図は酸化イリジウムの熱力学安定性を示す図である。縦軸は、アノード集電体１０６の電位を示し、横軸は、アノード電極１０２の水素イオン濃度であるペ－ハー（ＰＨ）を示している。 FIG. 9 is a diagram showing a control example of the control unit 40 according to this embodiment. The figure on the left shows the thermodynamic stability of iridium oxide. The vertical axis indicates the potential of the anode current collector 106 and the horizontal axis indicates pH (PH), which is the hydrogen ion concentration of the anode electrode 102 .
　本実施形態では、アノード電極１０２の電位を水素基準に対して第１電位よりも低くし、且つ、所定金属の溶出電位以上となるように制御している状態を第２モード（停止モード）と称する。例えば、アノード電極１０２の触媒が酸化イリジウムを含む場合、第２モードは、アノード電極１０２の電位を水素基準における第１電圧よりも低く、且つ例え酸化イリジウムの溶出電位以上にし、水素の生成が停止される状態である。 In the present embodiment, the second mode (stop mode) is a state in which the potential of the anode electrode 102 is controlled to be lower than the first potential relative to hydrogen and equal to or higher than the elution potential of a predetermined metal. called. For example, when the catalyst of the anode electrode 102 contains iridium oxide, the second mode is to make the potential of the anode electrode 102 lower than the first voltage based on hydrogen and, for example, equal to or higher than the elution potential of iridium oxide, and the generation of hydrogen stops. It is in a state where
　本実施形態では、制御部４０は、水電解セル２０ａに対して、第１モード（稼働モード）の状態Ｓｔ１０の制御を行った後に、第２モード（停止モード）の状態Ｓｔ１６の制御を行う。
　上述のように、アノード集電体１０６と、カソード集電体１０８との間の電位は、水素基準の電位と同等である。このため、第２モード（停止モード）において、接続制御部４０４は、スイッチＴ１０を導通状態とし、スイッチＴ１２、Ｔ１４を非導通状態を維持して、単セル１００ａのアノード集電体１０６と、カソード集電体１０８との間に、第２電位を印加しても良い。 In the present embodiment, the control unit 40 controls the water electrolysis cell 20a in the state St10 of the first mode (operation mode), and then controls the state St16 of the second mode (stop mode).
As noted above, the potential between the anode current collector 106 and the cathode current collector 108 is comparable to that of hydrogen. Therefore, in the second mode (stop mode), the connection control unit 404 brings the switch T10 into a conducting state and maintains the switches T12 and T14 into a non-conducting state so that the anode current collector 106 of the unit cell 100a and the cathode A second potential may be applied across the current collector 108 .
　図１０は、本実施形態に係る制御部４０の水電解セル２０ａに対する制御例を示すフローチャートである。図１０に示すように、まず、制御部４０は、第１循環ポンプ２４を制御し、気液分離機２３から供給される酸素を分離した水を、第１水入口マニホールド２１を介して、各単セル１００ａの供給部Ｇ２に供給する。続けて、接続制御部４０４は、スイッチＴ１０を導通状態とし、スイッチＴ１２、Ｔ１４を非導通状態とする。そして、電圧制御部４０６は、単セル１００ａのアノード集電体１０６と、カソード集電体１０８との間の電位が例えば１．８ボルトになるように、直流電源３０ａの電圧を制御し、第１モードを開始する（ステップＳ１００）。 FIG. 10 is a flowchart showing an example of control of the water electrolysis cell 20a by the controller 40 according to this embodiment. As shown in FIG. 10 , first, the control unit 40 controls the first circulation pump 24 to supply oxygen-separated water supplied from the gas-liquid separator 23 through the first water inlet manifold 21 to each It is supplied to the supply section G2 of the single cell 100a. Subsequently, the connection control unit 404 brings the switch T10 into a conducting state and brings the switches T12 and T14 into a non-conducting state. Then, the voltage control unit 406 controls the voltage of the DC power supply 30a so that the potential between the anode current collector 106 and the cathode current collector 108 of the single cell 100a becomes, for example, 1.8 volts. 1 mode is started (step S100).
　次に、制御部４０は、第１モードを停止するか否かを判定し（ステップＳ１０２）、停止すると判定しない場合（ステップＳ１０２のＮＯ）、制御部４０は、ステップＳ１００からの処理を繰り返す。 Next, the control unit 40 determines whether or not to stop the first mode (step S102), and if it is not determined to stop (NO in step S102), the control unit 40 repeats the processing from step S100.
　一方で、停止すると判定する場合（ステップＳ１０２のＹＥＳ）、電圧制御部４０６は、単セル１００ａのアノード集電体１０６の電位が溶出電位以上、例えば水素基準の電位が１．０ボルト以上になるように、直流電源３０ａの電圧を制御する。続けて、制御部４０は、第１循環ポンプ２４を停止し、第２モードを開始する（ステップＳ１０４）。 On the other hand, when determining to stop (YES in step S102), the voltage control unit 406 causes the potential of the anode current collector 106 of the single cell 100a to be equal to or higher than the elution potential, for example, the hydrogen-based potential is equal to or higher than 1.0 V. , the voltage of the DC power supply 30a is controlled. Subsequently, the controller 40 stops the first circulation pump 24 and starts the second mode (step S104).
　次に、制御部４０は、運転を停止するか否かを判定し（ステップＳ１０６）、運転を停止すると判定する場合（ステップＳ１０６のＹＥＳ）、運転を停止する。一方で、運転を停止しないと判定する場合（ステップＳ１０６のＮＯ）、第１モードを再開するか否かを判定し（ステップＳ１０２）、第１モードを再開すると判定する場合（ステップＳ１０８のＹＥＳ）、ステップＳ１００からの処理を繰り返す。一方で、第１モードを再開しないと判定する場合（ステップＳ１０８のＮＯ）、ステップＳ１０４からの処理を繰り返す。 Next, the control unit 40 determines whether or not to stop the operation (step S106), and if it determines to stop the operation (YES in step S106), it stops the operation. On the other hand, if it is determined not to stop the operation (NO in step S106), it is determined whether or not to resume the first mode (step S102), and if it is determined to resume the first mode (YES in step S108). , the processing from step S100 is repeated. On the other hand, if it is determined not to restart the first mode (NO in step S108), the process from step S104 is repeated.
　以上説明したように、本実施形態によれば、第１モードでは、電源部３０を制御し、アノード電極１０２の電位が水素基準に対して第１電位（例えば１．８ボルト）以上となるように制御し、第２モードでは、アノード電極１０２の電位が水素基準に対して第１電位（例えば１．８ボルト）よりも低く、且つ、イリジウムの溶出電位（例えば１．０ボルト）以上となるように水電解セル２０ａの状態を制御する。これにより、第２モードで水素の生成を抑制或いは停止した場合にも、アノード電極１０２の金属触媒である酸化イリジウムの酸化還元反応を抑制でき、イリジウムの溶出を抑制できる。 As described above, according to the present embodiment, in the first mode, the power supply unit 30 is controlled so that the potential of the anode electrode 102 becomes equal to or higher than the first potential (for example, 1.8 volts) relative to the hydrogen standard. In the second mode, the potential of the anode electrode 102 is lower than the first potential (eg, 1.8 volts) relative to the hydrogen reference and is equal to or higher than the elution potential of iridium (eg, 1.0 volts). The state of the water electrolysis cell 20a is controlled as follows. As a result, even when hydrogen production is suppressed or stopped in the second mode, the oxidation-reduction reaction of iridium oxide, which is the metal catalyst of the anode electrode 102, can be suppressed, and the elution of iridium can be suppressed.
　（第２実施形態）
　第２実施形態に係る水電解装置１０ｂは、第２モードにおいて、カソード電極１０４に不活性ガスを供給することにより、アノード電極１０２の電位をイリジウムの溶出電位以上となるように制御する点で、第１実施形態と相違する。以下では第１実施形態に係る水電解装置１０ａと相違する点を説明する。 (Second embodiment)
In the second mode, the water electrolysis apparatus 10b according to the second embodiment controls the potential of the anode electrode 102 to be equal to or higher than the elution potential of iridium by supplying an inert gas to the cathode electrode 104. It differs from the first embodiment. Differences from the water electrolysis device 10a according to the first embodiment will be described below.
　図１１は、第２実施形態に係る水電解装置１０ｂの構成を示すブロック図である。この図１１に示すように、本実施形態に係る水電解装置１０ｂは、不活性ガス供給部５０を更に備える。 FIG. 11 is a block diagram showing the configuration of a water electrolysis device 10b according to the second embodiment. As shown in FIG. 11, the water electrolysis device 10b according to this embodiment further includes an inert gas supply unit 50. As shown in FIG.
　不活性ガス供給部５０は、制御部４０の制御に従い、不活性ガスを供給する。不活性ガス供給部５０は、例えば、窒素ボンベである。この場合、窒素が不活性ガスとして、供給される。不活性ガスは、窒素に限定されず、アルゴンなどの他の不活性ガスでもよい。 The inert gas supply unit 50 supplies inert gas under the control of the control unit 40 . The inert gas supply unit 50 is, for example, a nitrogen cylinder. In this case nitrogen is supplied as inert gas. The inert gas is not limited to nitrogen and may be other inert gases such as argon.
　不活性ガスマニホールド５２は、各単セル１００ａ（図２参照）のカソード電極１０４と、不活性ガス供給部５０とを連通する。これにより、不活性ガス供給部５０は、不活性ガスマニホールド５２を介して、各単セル１００ａ（図２参照）のカソード電極１０４に不活性ガスを供給する。 The inert gas manifold 52 communicates the cathode electrode 104 of each unit cell 100a (see FIG. 2) and the inert gas supply section 50. Thereby, the inert gas supply unit 50 supplies the inert gas to the cathode electrode 104 of each unit cell 100a (see FIG. 2) through the inert gas manifold 52. As shown in FIG.
　図１２は、第２実施形態に係る制御部４０の構成を示すブロック図である。この図１２に示すように、本実施形態に係る制御部４０は、ガス制御部４０８を更に備える。 FIG. 12 is a block diagram showing the configuration of the control unit 40 according to the second embodiment. As shown in FIG. 12, the controller 40 according to this embodiment further includes a gas controller 408 .
　図１３は、第２実施形態に係る制御部４０の制御例を示す図である。縦軸は、水素基準に対する電位を示し、横軸は時間を示す。図１３に示すように、制御部４０は、第１モードの制御を時間Ｔ１０行った後に、第２モードの制御を時間Ｔ１２行こなう。第１モードでは、ガス制御部４０８は、不活性ガス供給部５０からの不活性ガスの供給を停止する制御を行う。一方で、第２モードでは、不活性ガス供給部５０から不活性ガスを各単セル１００ａ（図２参照）のカソード電極１０４に供給する制御を行う。 FIG. 13 is a diagram showing a control example of the control unit 40 according to the second embodiment. The vertical axis indicates the potential relative to hydrogen, and the horizontal axis indicates time. As shown in FIG. 13, the control unit 40 performs the control in the second mode for a period of time T12 after performing the control in the first mode for a period of time T10. In the first mode, the gas control section 408 performs control to stop the supply of the inert gas from the inert gas supply section 50 . On the other hand, in the second mode, control is performed to supply the inert gas from the inert gas supply unit 50 to the cathode electrode 104 of each single cell 100a (see FIG. 2).
　第２モードで、不活性ガスを各単セル１００ａ（図２参照）のカソード電極１０４に供給を開始すると、カソード電極１０４の電位Ｌ１２は、上昇を開始し、電位１ボルトぐらいで安定する。一方で、アノード電極１０２の電位Ｌ１４は、第２モードが開始されると、低下を初め、カソード電極１０４と同電位になると低下を停止する。 In the second mode, when inert gas is started to be supplied to the cathode electrode 104 of each single cell 100a (see FIG. 2), the potential L12 of the cathode electrode 104 starts rising and stabilizes at about 1 volt. On the other hand, the potential L14 of the anode electrode 102 begins to decrease when the second mode is started, and stops decreasing when it reaches the same potential as that of the cathode electrode 104. FIG.
　なお、第２モードにおいて直流電源３０ａからの直流電位を加えてもよい。例えば、不活性ガスによるカソード電極１０４の電位上昇が１ボルトに達しない場合に、１ボルトの差分の電位を直流電源３０ａからカソード電極１０４に印可してもよい。この場合、接続制御部４０４は、スイッチＴ１０を導通状態とし、スイッチＴ１２、Ｔ１４を非導通状態として、単セル１００ａのアノード集電体１０６と、カソード集電体１０８との間に、第２電位を印可してもよい。例えば、不活性ガスによるカソード電極１０４の電位上昇が０．８ボルトである場合に、直流電源３０ａからカソード電極１０４に０．２ボルト以上印可する。これにより、アノード電極１０２の電位Ｌ１４は、水素基準で、１ボルトで安定する。 Note that a DC potential from the DC power supply 30a may be applied in the second mode. For example, when the potential increase of the cathode electrode 104 due to the inert gas does not reach 1 volt, a potential difference of 1 volt may be applied to the cathode electrode 104 from the DC power supply 30a. In this case, the connection control unit 404 turns on the switch T10 and turns off the switches T12 and T14 so that the second potential is applied between the anode current collector 106 and the cathode current collector 108 of the single cell 100a. may be printed. For example, when the potential increase of the cathode electrode 104 by the inert gas is 0.8 volts, 0.2 volts or more is applied to the cathode electrode 104 from the DC power source 30a. As a result, the potential L14 of the anode electrode 102 is stabilized at 1 volt based on hydrogen.
　一方で、第２モードで、不活性ガスを各単セル１００ａ（図２参照）のカソード電極１０４に供給しない場合には、上述のように、カソード電極１０４の電位は０ボルトとなる。この場合、アノード電極１０２の電位Ｌ１６は、第２モードが開始されると、カソード電極１０４から固体高分子電解質膜１０１を介してアノード電極１０２に水素がリークすることによって低下を初め、カソード電極１０４と同電位である０ボルトまで低下する。 On the other hand, in the second mode, when the inert gas is not supplied to the cathode electrode 104 of each single cell 100a (see FIG. 2), the potential of the cathode electrode 104 is 0 volts as described above. In this case, when the second mode is started, the potential L16 of the anode electrode 102 begins to decrease due to hydrogen leaking from the cathode electrode 104 through the solid polymer electrolyte membrane 101 to the anode electrode 102, and to 0 volts, which is the same potential as .
　このように、ガス制御部４０８は、第２モードの開始に合わせ、不活性ガス供給部５０からの不活性ガスの供給を開始する。これにより、カソード電極１０４の電位は、水素基準で、１ボルト以上に上昇させることが可能となる。このため、アノード電極１０２の電位Ｌ１４は、第２モードが開始されても、イリジウムの溶出電位以上となるように制御される。これにより、アノード電極１０２の金属触媒である酸化イリジウムの酸化還元反応を抑制可能となり、イリジウムの溶出を抑制できる。 Thus, the gas control unit 408 starts supplying the inert gas from the inert gas supply unit 50 at the start of the second mode. As a result, the potential of the cathode electrode 104 can be increased to 1 volt or more based on hydrogen. Therefore, the potential L14 of the anode electrode 102 is controlled to be equal to or higher than the elution potential of iridium even when the second mode is started. This makes it possible to suppress the oxidation-reduction reaction of iridium oxide, which is the metal catalyst of the anode electrode 102, and suppress the elution of iridium.
　（第３実施形態）
　第２実施形態に係る水電解装置１０ｃは、第２モードにおいて、カソード電極１０４に水を浸潤させることにより、アノード電極１０２の電位をイリジウムの溶出電位以上となるように制御する点で、第１実施形態と相違する。以下では第１実施形態に係る水電解装置１０ａと相違する点を説明する。 (Third embodiment)
The water electrolysis apparatus 10c according to the second embodiment controls the potential of the anode electrode 102 to be equal to or higher than the elution potential of iridium by infiltrating the cathode electrode 104 with water in the second mode. It differs from the embodiment. Differences from the water electrolysis device 10a according to the first embodiment will be described below.
　図１４は、第３実施形態に係る水電解装置１０ｃの構成を示すブロック図である。この図１４に示すように、本実施形態に係る水電解装置１０ｃは、水供給部６０を更に備える。水供給部６０は、第２循環ポンプ６３と、第２水タンク６４とを有する。第２水タンク６４は水電解セル２０ａよりも鉛直上方に備え付けられている。 FIG. 14 is a block diagram showing the configuration of a water electrolysis device 10c according to the third embodiment. As shown in FIG. 14, the water electrolysis device 10c according to this embodiment further includes a water supply section 60. As shown in FIG. The water supply section 60 has a second circulation pump 63 and a second water tank 64 . The second water tank 64 is provided vertically above the water electrolysis cell 20a.
　図１５は、第３実施形態に係る単セル１００ｂの構成例を示す図である。図１５に示すようにカソード電極１０４の第１面にカソード集電体１０８が配置され、第１面と対向する第２面に水流路１１０が形成される。このカソード集電体１０８はカーボンもしくは金属の多孔質材料から構成されている。水流路１１０の供給部Ｇ８から水が供給され、排出部Ｇ１０から排出される。 FIG. 15 is a diagram showing a configuration example of a unit cell 100b according to the third embodiment. As shown in FIG. 15, the cathode current collector 108 is arranged on the first surface of the cathode electrode 104, and the water flow path 110 is formed on the second surface facing the first surface. The cathode current collector 108 is made of a carbon or metal porous material. Water is supplied from the supply portion G8 of the water channel 110 and discharged from the discharge portion G10.
　再び図１４に示すように、各単セル１００ｂの供給部Ｇ８と第２水タンク６４とは、第２水入口マニホールド６１を介して連通している。一方で、各単単セル１００ｂの排出部Ｇ１０と第２循環ポンプ６３とは、第２水出口マニホールド６２を介して連通している。水電解セル２０ｂは、各単セル１００ｂを積層して構成される。 As shown in FIG. 14 again, the supply portion G8 of each unit cell 100b and the second water tank 64 are in communication via the second water inlet manifold 61. On the other hand, the outlet G10 of each unit cell 100b and the second circulation pump 63 are in communication via the second water outlet manifold 62. As shown in FIG. The water electrolysis cell 20b is configured by stacking each unit cell 100b.
　図１６は、第３実施形態に係る制御部４０の構成を示すブロック図である。この図１６に示すように、本実施形態に係る制御部４０は、水制御部４１０を更に備える。 FIG. 16 is a block diagram showing the configuration of the control unit 40 according to the third embodiment. As shown in FIG. 16 , the control section 40 according to this embodiment further includes a water control section 410 .
　図１７は、第３実施形態に係る制御部４０の制御例を示す図である。縦軸は、水素基準に対する電位を示し、横軸は時間を示す。図１６に示すように、制御部４０は、第１モードの制御を時間Ｔ１４行った後に、第２モードの制御を時間Ｔ１６行こなう。第１モードでは、アノード電極１０２内の一部の水は固体高分子電解質膜１００を介してカソード電極１０４側に移動する。 FIG. 17 is a diagram showing a control example of the control unit 40 according to the third embodiment. The vertical axis indicates the potential relative to hydrogen, and the horizontal axis indicates time. As shown in FIG. 16, the control unit 40 performs control in the second mode for time T16 after performing control in the first mode for time T14. In the first mode, part of the water in the anode electrode 102 moves to the cathode electrode 104 side through the solid polymer electrolyte membrane 100 .
　第１モードでは、水制御部４１０は、第２循環ポンプ６３を駆動させ、第２水出口マニホールド６２を介して吸引する。これより、第２水タンク６４内の水が第２水入口マニホールド６１を介して水流路１１０に供給される。また、第１モードでは、水流路１１０は、第２循環ポンプ６３により吸引されることにより、カソード電極１０４内部よりも負圧となる。このため、カソード電極１０４側に移動した水は、カソード集電体１０８が多孔質であることから、カソード集電体１０８を介して水流路１１０に移動する。これにより水素気液分離処理が可能となり、水素気液分離機２８の小サイズ化が可能となる。 In the first mode, the water control section 410 drives the second circulation pump 63 to suck water through the second water outlet manifold 62 . As a result, the water in the second water tank 64 is supplied to the water flow path 110 via the second water inlet manifold 61 . In addition, in the first mode, the water flow path 110 is sucked by the second circulation pump 63 so that the pressure inside the cathode electrode 104 becomes negative. Therefore, the water that has moved to the cathode electrode 104 side moves to the water flow path 110 via the cathode current collector 108 because the cathode current collector 108 is porous. As a result, the hydrogen gas-liquid separation process becomes possible, and the size of the hydrogen gas-liquid separator 28 can be reduced.
　一方で、第２モードでは、水制御部４１０は、第２循環ポンプ６３を停止さる。これにより、第２水タンク６４内の水は重力によって正圧となり、水流路１１０内の水は、カソード集電体１０８を介してカソード電極１０４に移動し、水素をカソード電極外部に排出する。これにより、カソード電極１０４の電位Ｌ１８は、上昇を開始し、電位１ボルトぐらいで安定する。一方で、アノード電極１０２の電位Ｌ２０は、第２モードが開始されると、低下を初め、カソード電極１０４と同電位になると低下を停止する。アノード電極１０２の電位Ｌ１６は、カソード電極１０４に水をパージしなかった場合の例である。 On the other hand, in the second mode, the water control section 410 stops the second circulation pump 63 . As a result, the water in the second water tank 64 becomes positive pressure due to gravity, the water in the water flow path 110 moves to the cathode electrode 104 via the cathode current collector 108, and hydrogen is discharged to the outside of the cathode electrode. As a result, the potential L18 of the cathode electrode 104 starts rising and stabilizes at about 1 volt. On the other hand, the potential L20 of the anode electrode 102 starts decreasing when the second mode is started, and stops decreasing when it becomes the same potential as that of the cathode electrode 104 . The potential L16 of the anode electrode 102 is an example when the cathode electrode 104 is not purged with water.
　なお、第２モードにおいて直流電源３０ａからの直流電位を加えてもよい。例えば、水のパージによるカソード電極１０４の電位上昇が１ボルに達しない場合に、１ボルトの差分の電位を直流電源３０ａからカソード電極１０４に印可してもよい。この場合、接続制御部４０４は、スイッチＴ１０を導通状態とし、スイッチＴ１２、Ｔ１４を非導通状態として、単セル１００ａのアノード集電体１０６と、カソード集電体１０８との間に、第２電位を印可してもよい。例えば、不活性ガスによるカソード電極１０４の電位上昇が０．８ボルトである場合に、直流電源３０ａからカソード電極１０４に０．２ボルト印可する。これにより、アノード電極１０２の電位Ｌ１４は、水素基準で、１ボルトで安定する。 Note that a DC potential from the DC power supply 30a may be applied in the second mode. For example, if the potential rise of the cathode electrode 104 due to the water purge does not reach 1 volt, a potential difference of 1 volt may be applied to the cathode electrode 104 from the DC power supply 30a. In this case, the connection control unit 404 turns on the switch T10 and turns off the switches T12 and T14 so that the second potential is applied between the anode current collector 106 and the cathode current collector 108 of the single cell 100a. may be printed. For example, when the potential increase of the cathode electrode 104 by the inert gas is 0.8 volts, 0.2 volts is applied to the cathode electrode 104 from the DC power source 30a. As a result, the potential L14 of the anode electrode 102 is stabilized at 1 volt based on hydrogen.
　このように、水制御部４１０は、第２モードの開始に合わせ、第２水タンク６４内から正圧で水の供給を開始する。これにより、水流路１１０内の水は、カソード集電体１０８を介してカソード電極１０４に移動し、水素はカソード電極外部に排出され、カソード電極１０４の電位Ｌ１８は、電位１ボルトぐらいで安定する。このため、アノード電極１０２の電位Ｌ２０は、第２モードが開始されても、イリジウムの溶出電位以上となるように制御される。これにより、アノード電極１０２の金属触媒である酸化イリジウムの酸化還元反応を抑制可能となり、イリジウムの溶出を抑制できる。 In this way, the water control unit 410 starts supplying water from the inside of the second water tank 64 under positive pressure in time with the start of the second mode. As a result, the water in the water channel 110 moves to the cathode electrode 104 through the cathode current collector 108, the hydrogen is discharged to the outside of the cathode electrode, and the potential L18 of the cathode electrode 104 stabilizes at about 1 volt. . Therefore, the potential L20 of the anode electrode 102 is controlled to be equal to or higher than the elution potential of iridium even when the second mode is started. This makes it possible to suppress the oxidation-reduction reaction of iridium oxide, which is the metal catalyst of the anode electrode 102, and suppress the elution of iridium.
　以上、本発明のいくつかの実施形態を説明したが、これらの実施形態は、例として提示したものであり、発明の範囲を限定することは意図していない。これら新規な実施形態は、その他の様々な形態で実施することが可能であり、発明の要旨を逸脱しない範囲で、種々の省略、置き換え、変更を行うことができる。これらの実施形態やその変形例は、発明の範囲や要旨に含まれると共に、特許請求の範囲に記載された発明とその均等の範囲に含まれる。 Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

Claims (9)

  1. 　一方の面にアノード電極を設置し、他方の面にカソード電極を設置した固体高分子電解質膜を用いて前記アノード電極に供給された水を電気分解して、水素と酸素を発生する水電解セルと、
    　前記アノード電極の電位を変更可能な電源部と、
    　第１モードでは、前記電源部を、前記アノード電極の電位が第１電位以上となるように制御し、
    　第２モードでは、前記アノード電極の電位が前記第１電位よりも低く、且つ、前記アノード電極における所定の金属触媒の溶出電位以上となるように前記水電解セルの状態を制御する、制御部と、
    　を備える、水電解装置。     A water electrolysis cell that electrolyzes water supplied to the anode electrode using a solid polymer electrolyte membrane having an anode electrode on one side and a cathode electrode on the other side to generate hydrogen and oxygen. and,
    a power supply unit capable of changing the potential of the anode electrode;
    in a first mode, controlling the power supply unit so that the potential of the anode electrode is equal to or higher than a first potential;
    a control unit for controlling the state of the water electrolysis cell such that the potential of the anode electrode is lower than the first potential and equal to or higher than a predetermined elution potential of the metal catalyst at the anode electrode in the second mode; ,
    A water electrolysis device.
  2. 　前記制御部は、前記第２モードにおいて前記電源部を制御し、
    　前記アノード電極の電位を、水素基準に対して前記溶出電位以上にする、請求項１に記載の水電解装置。     The control unit controls the power supply unit in the second mode,
    2. The water electrolysis device according to claim 1, wherein the potential of said anode electrode is set equal to or higher than said elution potential with respect to hydrogen.
  3. 　前記所定の金属触媒は酸化イリジウムであり、
    　前記制御部は、前記第２モードにおいて前記電源部を制御し、
    　前記アノード電極の電位を、水素基準に対して１ボルト以上にする、請求項１に記載の水電解装置。     the predetermined metal catalyst is iridium oxide;
    The control unit controls the power supply unit in the second mode,
    2. The water electrolysis device according to claim 1, wherein the potential of said anode electrode is set to 1 volt or more relative to hydrogen.
  4. 　前記所定の金属触媒は酸化イリジウムであり、
    　前記制御部は、前記第２モードにおいて前記電源部を制御し、
    　前記アノード電極の電位を、前記カソード電極に対して１ボルト以上にする、請求項１に記載の水電解装置。     the predetermined metal catalyst is iridium oxide;
    The control unit controls the power supply unit in the second mode,
    2. The water electrolysis device according to claim 1, wherein the potential of said anode electrode is set to 1 volt or more with respect to said cathode electrode.
  5. 　前記制御部は、前記カソード電極に不活性ガスを供給する不活性ガス供給部を制御し、前記第２モードにおいて前記カソード電極に不活性ガスを供給させる、請求項１乃至４のいずれか一項に記載の水電解装置。 5. The controller according to any one of claims 1 to 4, wherein the controller controls an inert gas supply unit that supplies the inert gas to the cathode electrode, and supplies the inert gas to the cathode electrode in the second mode. The water electrolysis device according to .
  6. 　前記カソード電極の第１面に多孔質体であるカソード集電体が配置され、前記第１面と対向する第２面に水流路が形成され、
    　前記制御部は、水流路に水を供給する水供給装置を制御し、
    　前記第２モードにおいて前記水流路の水の圧力を前記カソード電極内の水素の圧力よりも正圧とする、請求項１乃至４のいずれか一項に記載の水電解装置。     A cathode current collector, which is a porous body, is arranged on the first surface of the cathode electrode, and a water flow path is formed on the second surface facing the first surface,
    The control unit controls a water supply device that supplies water to the water flow path,
    The water electrolysis device according to any one of claims 1 to 4, wherein in said second mode, the pressure of water in said water flow path is made more positive than the pressure of hydrogen in said cathode electrode.
  7. 　前記制御部は、水素生成時である前記第１モードにおいて、前記水流路内の水の圧力を前記カソード電極内の水素の圧力よりも負圧とする、請求項６に記載の水電解装置。 7. The water electrolysis device according to claim 6, wherein the control unit makes the pressure of water in the water flow path lower than the pressure of hydrogen in the cathode electrode in the first mode during hydrogen generation.
  8. 　前記制御部は、前記アノード電極のペーハーに対する前記所定の金属触媒の溶出電位との関係に基づき、前記アノード電極の電位を制御する、請求項１乃至７のいずれか一項に記載の水電解装置。 The water electrolysis device according to any one of claims 1 to 7, wherein the control unit controls the potential of the anode electrode based on the relationship between the pH of the anode electrode and the elution potential of the predetermined metal catalyst. .
  9. 　一方の面にアノード電極を設置し、他方の面にカソード電極を設置した固体高分子電解質膜を用いて前記アノード電極に供給された水を電気分解して、水素と酸素を発生する水電解セルの制御方法であって、
    　第１モードでは、電源部を制御し、前記アノード電極の電位が第１電位以上となるように制御し、
    　第２モードでは、前記アノード電極の電位が前記第１電位よりも低く、且つ、所定の金属金属触媒の溶出電位以上となるように前記水電解セルの状態を制御する、水電解セルの制御方法。     A water electrolysis cell that electrolyzes water supplied to the anode electrode using a solid polymer electrolyte membrane having an anode electrode on one side and a cathode electrode on the other side to generate hydrogen and oxygen. A control method of
    In the first mode, controlling the power supply unit so that the potential of the anode electrode is equal to or higher than the first potential,
    In the second mode, the water electrolysis cell control method controls the state of the water electrolysis cell so that the potential of the anode electrode is lower than the first potential and equal to or higher than the elution potential of a predetermined metal-metal catalyst. .
PCT/JP2022/031094 2021-08-25 2022-08-17 Water electrolysis device, and method for controlling water electrolysis cell WO2023026926A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014091838A (en) * 2012-10-31 2014-05-19 Chlorine Engineers Corp Ltd Reverse current prevention method for ion exchange membrane electrolytic cell
WO2017188421A1 (en) * 2016-04-27 2017-11-02 デノラ・ペルメレック株式会社 Electrode for electrolysis, manufacturing method of electrode for electrolysis and electrolytic cell
JP2021105194A (en) * 2019-12-26 2021-07-26 Ｅｎｅｏｓ株式会社 Hydrogen generation system, hydrogen generation system control device and hydrogen generation system control method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014091838A (en) * 2012-10-31 2014-05-19 Chlorine Engineers Corp Ltd Reverse current prevention method for ion exchange membrane electrolytic cell
WO2017188421A1 (en) * 2016-04-27 2017-11-02 デノラ・ペルメレック株式会社 Electrode for electrolysis, manufacturing method of electrode for electrolysis and electrolytic cell
JP2021105194A (en) * 2019-12-26 2021-07-26 Ｅｎｅｏｓ株式会社 Hydrogen generation system, hydrogen generation system control device and hydrogen generation system control method

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