JP2023096216A - Method of suppressing degradation of anode in water electrolysis device - Google Patents

Abstract

To provide a method of suppressing degradation of an anode in an electrolysis device in a process of stopping hydrogen production.SOLUTION: The method of suppressing degradation of an anode in a water electrolysis device according to the present invention, suppresses the degradation of an anode by supplying the anode with a multiphase flow of an aqueous alkali solution and oxygen subsequent to shifting from an operation mode of producing hydrogen and oxygen to a stop mode, in a water electrolysis device comprising a diaphragm-electrode joint formed of a hydroxide-ion conductive diaphragm interposed between a cathode comprising a reduction catalyst supported by a base material and an anode comprising an oxidation catalyst supported by a base material.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a method of suppressing deterioration of an anode of a water electrolysis device.

Patent Document 1 discloses a water electrolysis system that electrolyzes water to produce hydrogen and oxygen.

This water electrolysis system uses a water electrolysis device in which a diaphragm is sandwiched between a cathode and an anode, and an electric current is passed between the cathode and the anode to electrolyze an alkaline aqueous solution to produce hydrogen at the cathode and oxygen at the anode. This is an alkaline water electrolysis system, which suppresses deterioration of the cathode by controlling the amount of hydrogen in the cathode in the process of stopping the production of hydrogen and oxygen.

JP 2020-196919 A

The present disclosure provides a method for suppressing anode deterioration in a water electrolysis device that suppresses potential changes in the anode when production of hydrogen and oxygen is stopped, and suppresses deterioration of the anode due to structural changes and deterioration of the anode.

A method for suppressing anode deterioration of a water electrolysis device according to the present disclosure is a water electrolysis device in which a diaphragm-electrode assembly in which a hydroxide ion conductive diaphragm is sandwiched between a cathode and an anode is sandwiched between a cathode separator and an anode separator. This is a method for suppressing deterioration of the anode.

The cathode has a structure in which a catalyst for causing a reductive reaction in which water becomes hydrogen and hydroxide ions is carried on an electron-conducting base material. The anode has a structure in which a catalyst for causing an oxidation reaction to generate oxygen and water from hydroxide ions is carried on an electron-conductive substrate.

The cathode separator is formed on the surface facing the cathode with the cathode flow path. The anode separator is formed on the surface facing the anode with the anode flow channel.

Then, in the method for suppressing anode deterioration of a water electrolysis device in the present disclosure, after shifting from an operation mode in which hydrogen and oxygen are produced in the water electrolysis device to a stop mode in which production of hydrogen and oxygen in the water electrolysis device is stopped, alkaline aqueous solution and oxygen is supplied to the anode channel to suppress deterioration of the anode.

In the method for suppressing anode deterioration of a water electrolysis device in the present disclosure, after the operation mode is shifted to the stop mode, the mixed-phase flow of the alkaline aqueous solution and oxygen is supplied to the anode. potential change can be suppressed. Therefore, structural change and deterioration of the anode can be prevented, and deterioration of the anode can be suppressed.

Schematic diagram showing a schematic configuration of a water electrolysis system according to Embodiment 1 Flowchart showing operation of the water electrolysis system in Embodiment 1 FIG. 3 is an explanatory diagram showing a state immediately after execution of S101 in the flowchart of FIG. 2 in the water electrolysis system according to Embodiment 1; FIG. 3 is an explanatory diagram showing a state immediately after execution of S102 in the flowchart of FIG. 2 in the water electrolysis system according to Embodiment 1; FIG. 3 is an explanatory diagram showing a state immediately after execution of S103 in the flowchart of FIG. 2 in the water electrolysis system according to Embodiment 1; FIG. 3 is an explanatory diagram showing a state immediately after execution of S104 in the flowchart of FIG. 2 in the water electrolysis system according to Embodiment 1; FIG. 3 is an explanatory diagram showing a state immediately after execution of S107 in the flowchart of FIG. 2 in the water electrolysis system according to Embodiment 1; FIG. 3 is an explanatory diagram showing a state immediately after execution of S108 in the flowchart of FIG. 2 in the water electrolysis system according to Embodiment 1; FIG. 3 is an explanatory diagram showing a state immediately after execution of S109 in the flowchart of FIG. 2 in the water electrolysis system according to Embodiment 1; FIG. 3 is an explanatory diagram showing a state immediately after execution of S110 in the flowchart of FIG. 2 in the water electrolysis system according to Embodiment 1; FIG. 3 is an explanatory diagram showing a state immediately after execution of S114 in the flowchart of FIG. 2 in the water electrolysis system according to Embodiment 1; FIG. 3 is an explanatory diagram showing a state immediately after execution of S115 in the flowchart of FIG. 2 in the water electrolysis system according to Embodiment 1; FIG. 3 is an explanatory diagram showing a state immediately after execution of S119 in the flowchart of FIG. 2 in the water electrolysis system according to Embodiment 1; FIG. 3 is an explanatory diagram showing a state immediately after execution of S120 in the flowchart of FIG. 2 in the water electrolysis system according to Embodiment 1;

(Knowledge, etc. on which this disclosure is based)
At the time when the inventors arrived at the present disclosure, water was electrolyzed by supplying an alkaline aqueous solution to at least one of the cathode and the anode of a water electrolysis device and applying a direct current between the cathode and the anode. Therefore, there was a technology to produce hydrogen at the cathode and oxygen at the anode.

As a result, it is possible to convert surplus electric power derived from renewable energy such as solar power and wind power, whose output fluctuates greatly, into hydrogen.

However, when the production of hydrogen and oxygen is stopped (shifted from operation mode to stop mode) in response to fluctuations in renewable energy, the water electrolysis device deteriorates, and the energy efficiency after restarting operation decreases. was there. Here, the energy efficiency is the ratio of the theoretical energy required for water electrolysis to the electrical energy input to the water electrolysis device.

Therefore, in the industry, the phenomenon that the amount of hydrogen in the cathode changes and the potential of the cathode changes after shifting from the operation mode to the stop mode is presumed as a factor of the decrease in energy efficiency. As a countermeasure, an operating method for controlling the amount of hydrogen in the cathode in the stop mode has been studied.

However, regarding the decrease in the energy efficiency of water electrolysis devices, consideration of deterioration factors other than the cathode, deterioration mechanisms, evaluation methods, and the like have not been sufficiently investigated.

Under such circumstances, the inventors conducted a cycle test in which the water electrolysis device was alternately operated and stopped. As a result, the phenomenon of early deterioration of the anode was found to be a factor in lowering the energy efficiency.

In general, the anode has a structure in which a catalyst such as an oxide or hydroxide is supported on the surface of a base material having electronic conductivity. , it was confirmed that the potential of the anode changes early.

It was also confirmed that by alternately repeating the operation and stoppage of the water electrolysis device, the potential of the anode was repeatedly changed, and as a result, the structure of the anode was changed.

Furthermore, it was confirmed that a part of the remaining catalyst was also deteriorated due to the potential change of the anode, and the catalytic activity was lowered.

Based on the above test results, an operation method for controlling changes in the potential of the anode was investigated. As a result, it was found that the potential of the anode can be controlled by the amount of oxygen in the anode and the pH of the alkaline aqueous solution. Arrived.

Therefore, the present disclosure suppresses deterioration of the anode by suppressing structural change and deterioration of the anode by supplying a multiphase flow containing an alkaline aqueous solution and oxygen to the anode after shifting from the operation mode to the stop mode. Provide a water electrolysis system.

Hereinafter, embodiments will be described in detail with reference to the drawings. However, more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters or redundant descriptions of substantially the same configurations may be omitted.

It should be noted that the accompanying drawings and the following description are provided for a thorough understanding of the present disclosure by those skilled in the art and are not intended to limit the claimed subject matter.

(Embodiment 1)
Embodiment 1 will be described below with reference to FIGS. 1 to 5. FIG.

[1-1. composition]
[1-1-1. Structure of Diaphragm-Electrode Assembly]
As shown in FIG. 1, the diaphragm-electrode assembly 104 is constructed such that the cathode 102 and the anode 103 sandwich the main surface of the hydroxide ion conductive diaphragm 101 .

The size of the main surface of the cathode 102 and the anode 103 is smaller than that of the main surface of the diaphragm 101, and the cathode 102 and the anode 103 are arranged so that the peripheral area of the main surface of the diaphragm 101 is exposed.

The diaphragm 101 is a dense membrane composed of a polymer containing ion-exchangeable hydroxide ions. Specifically, the diaphragm 101 is composed of a polymer having a quaternary amine such as a trimethylammonium group as a hydroxide ion exchange group.

The thickness of diaphragm 101 is not particularly limited, but may be, for example, a thickness of 5 to 1000 μm. In the present embodiment, diaphragm 101 with a thickness of 100 μm was used.

In the present embodiment, an anion exchange membrane (Sustanion (registered trademark) X37) manufactured by Dioxide Materials having a square shape with a side length of 100 mm was used as the diaphragm 101 containing hydroxide ions.

The cathode 102 has a cathode catalyst layer laminated on one main surface of the diaphragm 101 and a cathode catalyst layer laminated on the surface of the cathode catalyst layer opposite to the surface in contact with the diaphragm 101 so that the cathode catalyst layer is not exposed. It is composed of layers and The size of the main surface of the cathode gas diffusion layer is substantially the same as the size of the main surface of the cathode catalyst layer.

The cathode catalyst layer is composed of a cathode catalyst, a cathode base material supporting the cathode catalyst, and an ionomer covering at least part of the outer surface of the cathode base material supporting the cathode catalyst. The cathode catalyst layer functions to promote an electrochemical reaction that produces hydrogen from water contained in the alkaline aqueous solution supplied to the cathode catalyst layer.

Cathode catalyst materials include simple transition metals such as iron, nickel, and cobalt, their oxides and hydroxides, alloys, oxides, and hydroxides composed of multiple metal elements, and mixtures thereof, platinum and iridium. and other noble metals and their oxides can be used.

The cathode base material is composed of a particulate, fibrous, or porous material having electronic conductivity. Carbon, nickel, nickel alloys, titanium, titanium-based alloys, mild steel, stainless steel, and the like can be used as materials for the cathode base material in terms of resistance to the environment in which they are used.

In the present embodiment, platinum-supported carbon particles (TEC10E50E) manufactured by Tanaka Kikinzoku Co., Ltd. were used as the cathode catalyst and the cathode base material (cathode base material supporting the cathode catalyst). As an ionomer, an electrolytic resin (Sustanion (registered trademark) XA-9 5% dispersion) manufactured by Dioxide Materials was used.

For the cathode catalyst layer, for example, a cathode catalyst slurry prepared by dispersing a cathode catalyst, a cathode base material, and an ionomer in a dispersion medium is applied to the diaphragm 101 by a spray coater, and then the dispersion medium is applied. can be formed by removing by heating and drying.

In the present embodiment, 25 parts by weight of a cathode catalyst and a cathode base material, 15 parts by weight of an ionomer, and a dispersion medium composed of 15 parts by weight of pure water and 45 parts by weight of ethanol are collected in a container and mixed. The resulting mixture was kneaded at room temperature for 2 hours to obtain a cathode catalyst slurry. A disperser and an ultrasonic homogenizer were used for kneading.

Then, the obtained cathode catalyst slurry was applied to the central region of one main surface of the diaphragm 101 other than the peripheral region using a spray coater.

Then, the diaphragm 101 coated with the cathode catalyst slurry was placed in a thermostat and heated at a temperature of 80° C. for 1 hour to remove the dispersion medium from the cathode catalyst slurry coated on the diaphragm 101 . Thereafter, the diaphragm 101 was cooled at room temperature for 2 hours to form a cathode catalyst layer on one main surface of the diaphragm 101 .

The thickness of the cathode catalyst layer is not particularly limited, but may be, for example, 5 to 1000 μm. formed.

The anode 103 is composed of an anode catalyst layer laminated on the other main surface of the diaphragm 101 and a surface of the anode catalyst layer opposite to the surface in contact with the diaphragm 101 so that the anode catalyst layer is not exposed. It is composed of layers and The size of the main surface of the anode gas diffusion layer is substantially the same as that of the main surface of the anode catalyst layer.

The anode catalyst layer is composed of an anode catalyst, an anode substrate supporting a cathode catalyst, and an ionomer covering at least part of the outer surface of the anode substrate supporting the cathode catalyst. The anode catalyst layer functions to promote an electrochemical reaction that produces oxygen and water from hydroxide ions supplied to the anode catalyst layer.

Materials for the anode catalyst include simple transition metals such as iron, nickel and cobalt, their oxides and hydroxides, alloys, oxides and hydroxides composed of multiple metal elements, their mixtures, platinum and iridium. and other noble metals and their oxides can be used.

The anode base material is composed of a particulate, fibrous, or porous material having electronic conductivity. Carbon, nickel, nickel alloys, titanium, titanium-based alloys, mild steel, stainless steel, and the like can be used as materials for the anode base material in terms of resistance to the environment in which they are used.

In this embodiment, nickel nanoparticles (100 nm) manufactured by US Research Nanomaterials were used as the cathode base material. As a cathode catalyst, hydroxide particles containing nickel and iron synthesized by a sol-gel method were supported on the cathode substrate.

As an ionomer, an electrolytic resin (Sustanion® XA-9 5% dispersion) manufactured by Dioxide Materials was used.

The anode catalyst layer is formed by, for example, applying an anode catalyst slurry prepared by dispersing an anode catalyst, an anode substrate, and an ionomer in a dispersion medium to the separation membrane 101 with a spray coater, followed by dispersing the dispersion medium. can be formed by removing by heating and drying.

In the present embodiment, 35 parts by weight of the anode catalyst and the anode base material, 5 parts by weight of the ionomer, and a dispersion medium composed of 15 parts by weight of pure water and 45 parts by weight of ethanol are collected in a container and mixed. The resulting mixture was kneaded at room temperature for 2 hours to obtain an anode catalyst slurry. A disperser and an ultrasonic homogenizer were used for kneading.

Then, the obtained anode catalyst slurry was applied to the central region other than the peripheral region of the other main surface of the diaphragm 101 by a spray coating machine.

Then, the diaphragm 101 coated with the anode catalyst slurry was placed in a thermostat and heated at a temperature of 80° C. for 1 hour to remove the dispersion medium. After that, the anode catalyst layer was formed on the other main surface of the diaphragm 101 by cooling the diaphragm 101 at room temperature for 2 hours.

The thickness of the anode catalyst layer is not particularly limited, but may be, for example, 5 to 1000 μm. formed.

The cathode gas diffusion layer is made of a fibrous or porous material having gas permeability and electronic conductivity. Carbon, nickel, nickel alloys, titanium, titanium-based alloys, mild steel, stainless steel, and the like can be used as materials for the cathode gas diffusion layer in terms of resistance to the environment in which they are used.

In this embodiment, carbon paper (TGP-H-120) manufactured by Toray Industries, Inc. having a square shape with a side length of 80 mm was used as the cathode gas diffusion layer.

The anode gas diffusion layer is composed of a fibrous or porous material having gas permeability and electronic conductivity. Carbon, nickel, nickel alloys, titanium, titanium-based alloys, mild steel, stainless steel, etc. can be used as the material of the anode gas diffusion layer in terms of resistance to the environment in which it is used.

In the present embodiment, a nickel fiber (Bekipor (registered trademark)) manufactured by Bekaert Co., Ltd. and having a square shape with a side length of 80 mm was used as the anode gas diffusion layer.

A diaphragm 101 having a cathode catalyst layer formed on one main surface and an anode catalyst layer formed on the other main surface, a cathode gas diffusion layer, and an anode gas diffusion layer are arranged so that the cathode gas diffusion layer faces the cathode catalyst layer. and the anode gas diffusion layer facing the anode catalyst layer, and hot pressed at a pressure of 2 MPa and a temperature of 130° C. for 10 minutes to form a cathode 102 and an anode 103 on the diaphragm 101. An electrode assembly 104 was obtained.

[1-1-2. Configuration of water electrolysis device]
As shown in FIG. 1, the water electrolysis device 100 has a structure in which a diaphragm-electrode assembly 104 is sandwiched between a cathode separator 105 and an anode separator .

The diaphragm-electrode assembly 104 is arranged so that both main surfaces are substantially parallel to the direction of gravity, and is sandwiched between a cathode separator 105 and an anode separator 106 for use.

At this time, seals mainly made of resin, which are elastically deformed by being sandwiched between the cathode separator 105 or the anode separator 106 and the diaphragm 101, are provided in the peripheral regions of both main surfaces of the diaphragm-electrode assembly 104. A member is further arranged to prevent leakage of the alkaline aqueous solution and gas generated by water electrolysis from the water electrolysis device 100 .

On the other hand, in the central region of the diaphragm-electrode assembly 104, the cathode separator 105 is in contact with the cathode 102 on one main surface, and the anode separator 106 is in contact with the anode 103 on the other main surface. ing.

The cathode separator 105 has a cathode inlet 107, a cathode outlet 108, and a cathode channel 109, respectively. , the cathode 102 , the alkaline aqueous solution supplied to the cathode 102 , and the hydrogen produced at the cathode 102 .

Here, the cathode inlet 107 is a through hole formed on the lower side of the cathode separator 105 in a direction substantially perpendicular to the main surface of the diaphragm-electrode assembly 104, and is a hole for supplying the alkaline aqueous solution to the cathode 102. is.

The cathode outlet 108 is a through-hole formed on the upper side of the cathode separator 105 in a direction substantially perpendicular to the main surface of the diaphragm-electrode assembly 104, and is used for the remaining aqueous alkaline solution not used for water electrolysis at the cathode 102. , and hydrogen produced at the cathode 102 are discharged from the cathode 102 .

In the cathode flow channel 109, along the surface of the cathode 102 opposite to the surface in contact with the diaphragm 101, the alkaline aqueous solution flowing from the cathode inlet 107 meanders in a substantially horizontal direction toward the cathode outlet 108, while the cathode separator 105 and the cathode 102 .

The cathode separator 105 is made of a material that is gas impermeable and electronically conductive. Carbon, nickel, nickel alloys, titanium, titanium-based alloys, mild steel, stainless steel, and the like can be used as materials for the cathode separator 105 in terms of resistance to the environment in which they are used. In this embodiment, nickel is used as the material of the cathode separator 105 .

The portion where the cathode channel 109 and the cathode inlet 107 connect is near the lower end of the main surface of the cathode 102, and the portion where the cathode channel 109 and the cathode outlet 108 connect is the upper end of the main surface of the cathode 102. Nearby.

The anode separator 106 has an anode inlet 110, an anode outlet 111, and an anode channel 112, respectively. , the anode 103, the alkaline aqueous solution supplied to the anode 103, the oxygen produced by the anode 103, and the water produced by the anode 103 during oxygen production.

Here, the anode inlet 110 is a through hole formed on the lower side of the anode separator 106 in a direction substantially perpendicular to the main surface of the diaphragm-electrode assembly 104, and is a hole for supplying the alkaline aqueous solution to the anode 103. is.

The anode outlet 111 is a through hole formed on the upper side of the anode separator 106 in a direction substantially perpendicular to the main surface of the diaphragm-electrode assembly 104, and is produced by the alkaline aqueous solution supplied to the anode 103 and the anode 103. These are holes for discharging oxygen and water produced at the anode 103 during oxygen production from the anode 103 .

In the anode flow channel 112, along the surface of the anode 103 opposite to the surface in contact with the diaphragm 101, the alkaline aqueous solution flowing from the anode inlet 110 meanders in a substantially horizontal direction toward the anode outlet 111, while the anode separator 106 and the anode 103 .

The anode separator 106 is made of a material that is gas impermeable and electronically conductive. Carbon, nickel, nickel alloys, titanium, titanium-based alloys, mild steel, stainless steel, and the like can be used as the material of the anode separator 106 in terms of resistance to the environment in which it is used. In this embodiment, nickel is used as the material of the anode separator 106 .

[1-1-3. Configuration of water electrolysis system]
As shown in FIG. 1, water electrolysis system 180 in the present embodiment includes water electrolysis device 100, cathode aqueous solution supply means 121, anode aqueous solution supply means 122, oxygen supply means 125, hydrogen storage chamber 126, It comprises an oxygen reservoir 127 , a power supply 128 , a voltmeter 129 and a controller 130 .

The cathode aqueous solution supply means 121 is configured to supply the alkaline aqueous solution under predetermined conditions (temperature, pH, flow rate) to the cathode 102, and can be used in combination with the cathode pH adjustment means 123, for example. Thereby, an alkaline aqueous solution controlled to a predetermined pH can be supplied to the cathode 102 .

The cathode aqueous solution supply means 121 is configured to gas-liquid separate the hydrogen discharged from the cathode outlet 108 and the alkaline aqueous solution, and is configured to supply the gas-liquid separated hydrogen to the hydrogen storage chamber 126 . It is

In this embodiment, the cathode aqueous solution supply means 121 includes an alkaline aqueous solution tank, a gas-liquid separation tank, an alkaline aqueous solution supply pump, a hydrogen supply pump, a temperature controller, a pressure controller, and a check valve. , was used.

The cathode pH adjusting means 123 is configured to control the pH of the alkaline aqueous solution supplied from the cathode aqueous solution supplying means 121 , and supplies the cathode aqueous solution supplying means 121 with a pH adjuster adjusted to a predetermined pH.

In the present embodiment, the cathode pH adjusting means 123 includes a pH adjusting agent storage tank, a pH adjusting agent supply pump, a water tank for diluting the pH of the pH adjusting agent, a water supply pump, a pH meter, A temperature controller and a check valve were used.

The anode aqueous solution supply means 122 is configured to supply an alkaline aqueous solution under predetermined conditions (temperature, pH, flow rate) to the anode 103, and can be used in combination with the anode pH adjustment means 124, for example. Thereby, the alkaline aqueous solution controlled to a predetermined pH can be supplied to the anode 103 .

Further, the anode aqueous solution supply means 122 is configured to gas-liquid separate the oxygen discharged from the anode outlet 111 and the alkaline aqueous solution, and is configured to supply the gas-liquid separated oxygen to the oxygen storage chamber 127 . It is

In this embodiment, the anode aqueous solution supply means 122 includes an alkaline aqueous solution tank, a gas-liquid separation tank, an alkaline aqueous solution supply pump, an oxygen supply pump, a temperature regulator, a pressure regulator, and a check valve. , was used.

The anode pH adjusting means 124 is configured to control the pH of the alkaline aqueous solution supplied from the anode aqueous solution supplying means 122 , and supplies the anode aqueous solution supplying means 122 with a pH adjuster adjusted to a predetermined pH.

In this embodiment, the anode pH adjusting means 124 includes a pH adjusting agent storage tank, a pH adjusting agent supply pump, a water tank for diluting the pH of the pH adjusting agent, a water supply pump, a pH meter, A temperature controller and a check valve were used.

The oxygen supply means 125 is configured to supply oxygen under predetermined conditions (temperature, flow rate) to the anode 103 . For example, by using the anode aqueous solution supply means 122 in combination, it is possible to supply the anode 103 with a mixed phase flow of an alkaline aqueous solution and oxygen controlled to predetermined conditions (temperature, pH, flow rate).

In this embodiment, the oxygen supply means 125 includes an oxygen supply pump, a temperature regulator, a pressure regulator, and a check valve.

The cathode supply path 141 is a path that connects the alkaline aqueous solution outlet of the cathode aqueous solution supply means 121 and the cathode inlet 107 . A cathode inlet valve 150 for opening and closing the cathode supply path 141 is arranged in the middle of the cathode supply path 141 . Thereby, the alkaline aqueous solution controlled to predetermined conditions can be supplied to the cathode 102 .

The cathode discharge path 142 is a path that connects the cathode outlet 108 and the inlets of hydrogen and alkaline aqueous solution in the cathode aqueous solution supply means 121 . A cathode outlet valve 151 for opening and closing the cathode discharge path 142 is arranged in the middle of the cathode discharge path 142 . Thereby, the hydrogen and alkaline aqueous solution discharged from the cathode 102 can be supplied to the cathode aqueous solution supply means 121 .

The hydrogen discharge path 145 is a path that connects the hydrogen outlet of the cathode aqueous solution supply means 121 and an external infrastructure. In the middle of the hydrogen discharge path 145, a hydrogen inlet valve 152,
A hydrogen storage chamber 126 is arranged downstream of the hydrogen inlet valve 152 and a hydrogen outlet valve 153 is arranged downstream of the hydrogen storage chamber 126 . Thereby, the gas-liquid separated hydrogen can be supplied to the external infrastructure via the hydrogen storage chamber 126 .

The anode supply path 143 is a path that connects the alkaline aqueous solution outlet of the anode aqueous solution supply means 122 and the anode inlet 110 . In the middle of the anode supply path 143, an anode inlet switching valve 154 having two inlets and one outlet, capable of opening and closing the anode supply path 143 and capable of simultaneously communicating both inlets and outlets, is arranged. there is This makes it possible to supply the anode 103 with an alkaline aqueous solution controlled to a predetermined condition.

The anode discharge path 144 is a path that connects the anode outlet 111 and the inlets of oxygen and alkaline aqueous solution in the anode aqueous solution supply means 122 . An anode outlet valve 155 for opening and closing the anode discharge path 144 is arranged in the middle of the anode discharge path 144 . Thereby, the oxygen and the alkaline aqueous solution discharged from the anode 103 can be supplied to the anode aqueous solution supply means 122 .

The oxygen discharge path 146 is a path that connects the oxygen outlet of the aqueous anode solution supply means 122 and the external infrastructure. An oxygen inlet valve 156 , an oxygen storage chamber 127 on the downstream side of the oxygen inlet valve 156 , and an oxygen outlet valve 157 on the downstream side of the oxygen storage chamber 127 are arranged in the middle of the oxygen discharge path 146 . As a result, the gas-liquid separated oxygen can be supplied to the external infrastructure via the oxygen storage chamber 127 .

The oxygen supply path 147 is a path that connects the oxygen storage chamber 127 and an inlet other than the inlet of the anode inlet switching valve 154 on the anode aqueous solution supply means 122 side. An oxygen supply valve 158 and an oxygen supply means 125 between the oxygen supply valve 158 and the anode inlet switching valve 154 are arranged in the middle of the oxygen supply path 147 . Thereby, the oxygen stored in the oxygen storage chamber 127 can be controlled to a predetermined condition and supplied to the anode 103 .

In addition, by using the anode aqueous solution supply means 122 and the oxygen supply means 125 in combination, and by setting the anode inlet switching valve 154 to a state in which both inlets and outlets can be simultaneously communicated, alkaline A multiphase flow of aqueous solution and oxygen can be supplied to the anode 103 .

The power supply 128 is a constant-current DC power supply that supplies a specified current value. A positive output terminal of the power supply 128 is electrically connected to the anode 103 and a negative output terminal of the power supply 128 is electrically connected to the cathode 102 .

Voltmeter 129 measures the voltage between cathode 102 and anode 103 or the potential of anode 103 . Here, when measuring the voltage between the cathode 102 and the anode 103, one terminal of the voltmeter 129 is connected to the cathode 102 and the other terminal is connected to the anode 103, and the potential difference between the two electrodes, that is, the voltage is detected. be done.

Moreover, when measuring the potential of the anode 103 , a reference electrode is provided on the diaphragm 101 . The reference electrode is a standard hydrogen electrode (SHE), one terminal of the voltmeter 129 is connected to the reference electrode and the other terminal is connected to the anode 103, and the potential of the electrode with respect to the reference electrode is detected. .

Controller 130 controls cathode aqueous solution supply means 121, anode aqueous solution supply means 122, cathode pH adjustment means 123, anode pH adjustment means 124, oxygen supply path 147, oxygen supply means 125, cathode inlet valve 150, cathode outlet valve 151, hydrogen It is connected to inlet valve 152 , hydrogen outlet valve 153 , anode inlet switching valve 154 , anode outlet valve 155 , oxygen inlet valve 156 , oxygen outlet valve 157 , oxygen supply valve 158 , power supply 128 and voltmeter 129 .

The controller 130 operates an operation mode, a shutdown mode, and a stop mode, which will be described in 1-2 below, by controlling each device.

As described above, in the water electrolysis system 180 of the present embodiment, the water electrolysis device 100 in which the membrane-electrode assembly 104 is sandwiched between the cathode separator 105 and the anode separator 106 and the membrane-electrode assembly 104 are supplied with current. A power supply 128 , a cathode aqueous solution supply means 121 , an anode aqueous solution supply means 122 and an oxygen supply means 125 are provided.

The diaphragm-electrode assembly 104 has a configuration in which a hydroxide ion conductive diaphragm is sandwiched between a cathode 102 and an anode 103 . The cathode 102 has a structure in which a catalyst for causing a reductive reaction in which water becomes hydrogen and hydroxide ions is supported on an electron-conducting substrate. The anode 103 has a structure in which a catalyst for causing an oxidation reaction to generate oxygen and water from hydroxide ions is supported on an electron conductive substrate.

The cathode separator 105 has a cathode channel 109 that communicates a cathode inlet 107 and a cathode outlet 108 on a surface facing the cathode 102 . The anode separator 106 has an anode channel 112 that communicates between an anode inlet 110 and an anode outlet 111 and is formed on a surface facing the anode 103 .

A power supply 128 is electrically connected to the cathode 102 and the anode 103 and supplies power to the cathode 102 such that, in the operating mode in which the water electrolysis device 100 produces hydrogen and oxygen, a reduction reaction occurs at the cathode 102 and an oxidation reaction occurs at the anode 103 . It is configured to pass current between 102 and anode 103 .

In the operation mode, the cathode aqueous solution supply means 121 supplies the alkaline aqueous solution controlled to a predetermined pH by the cathode pH adjustment means 123 to the cathode inlet 107 through the cathode supply path 141 and the cathode discharge path 142 from the cathode outlet 108 . It is configured to separate the hydrogen and the alkaline aqueous solution discharged to the gas-liquid.

Furthermore, the cathode aqueous solution supply means 121 is configured to control the separated alkaline aqueous solution to a predetermined pH by the cathode pH adjustment means 123 and reuse it, and to discharge the separated hydrogen to the hydrogen discharge path 145 . there is

The anode aqueous solution supply means 122 supplies an alkali solution whose pH is controlled to a predetermined value by the anode pH adjustment means 124 during the operation mode and after transitioning from the operation mode to the stop mode in which the production of hydrogen and oxygen in the water electrolysis device 100 is stopped. The aqueous solution is supplied to the anode inlet 110 through the anode supply path 143, and the oxygen and alkaline aqueous solution discharged from the anode outlet 111 to the anode discharge path 144 are separated into gas and liquid.

Furthermore, the anode aqueous solution supply means 122 controls the separated alkaline aqueous solution to a predetermined pH by the anode pH adjustment means 124 and reuses it, and the separated oxygen is supplied to the oxygen storage chamber 127 through the oxygen discharge path 146. configured to supply to

The oxygen supply means 125 is provided in the oxygen supply path 147 that communicates the oxygen storage chamber 127 and the anode supply path 143, and after the operation mode is shifted to the stop mode, the mixed phase flow of the alkaline aqueous solution and oxygen is supplied to the anode 103. As shown, the oxygen in the oxygen storage chamber 127 is mixed with the alkaline aqueous solution flowing through the anode supply path 143 .

The water electrolysis system 180 of this embodiment includes a controller 130 that controls the power source 128 , the cathode aqueous solution supply means 121 , the anode aqueous solution supply means 122 and the oxygen supply means 125 .

Power supply 128 is configured to pass current between cathode 102 and anode 103 under the control of controller 130 during the run mode.

The cathode aqueous solution supply means 121 is controlled by the controller 130 to supply the alkaline aqueous solution controlled to a predetermined pH to the cathode inlet 107 in the operation mode, and the hydrogen discharged from the cathode outlet 108 and the alkaline aqueous solution are supplied. Gas-liquid separation is performed, and the alkaline aqueous solution after separation is reused, and hydrogen after separation is discharged to hydrogen discharge path 145 .

The anode aqueous solution supply means 122 is controlled by the controller 130 to supply an alkaline aqueous solution controlled to a predetermined pH to the anode inlet 110 during the operation mode and after transition from the operation mode to the stop mode, and to the anode outlet 111. The oxygen and the alkaline aqueous solution discharged from are separated into gas and liquid, the separated alkaline aqueous solution is reused, and the separated oxygen is supplied to the oxygen storage chamber 127 .

The oxygen supply means 125 is controlled by the controller 130 to flow through the anode supply path 143 so that the mixed phase flow of the alkaline aqueous solution and oxygen is supplied to the anode 103 after the operation mode is shifted to the stop mode. It is configured to mix oxygen into the alkaline aqueous solution.

The water electrolysis system 180 of this embodiment includes a voltmeter 129 that can measure the voltage between the cathode 102 and the anode 103 or the potential of the anode 103 .

The controller 130 controls the supply of the mixed phase flow of the alkaline aqueous solution and oxygen to the anode 103 when the value measured by the voltmeter 129 becomes smaller than the specified value after the transition from the operation mode to the stop mode. In addition, it is configured to control the anode aqueous solution supply means 122 and the oxygen supply means 125 .

The controller 130 of the water electrolysis system 180 of the present embodiment controls the pH value of the alkaline aqueous solution controlled by the anode pH adjusting means 124 when supplying the mixed-phase flow of the alkaline aqueous solution and oxygen to the anode 103. The anode pH adjusting means 124 is configured to be lower than the pH value of the alkaline aqueous solution controlled by the pH adjusting means 124 .

The water electrolysis system 180 of the present embodiment is configured to transition from an operation mode to a shutdown mode via a shutdown mode. is gradually decreased, and the anode pH adjustment means 124 is adjusted so that the pH value of the alkaline aqueous solution supplied to the anode 103 by the anode aqueous solution supply means 122 is gradually lowered. It is configured.

Controller 130 of water electrolysis system 180 of the present embodiment controls anode aqueous solution supply means 122 and oxygen supply means 125 so that a multiphase flow containing an alkaline aqueous solution and oxygen is supplied to anode 103. When a predetermined condition is satisfied, the supply operations of the anode aqueous solution supply means 122 and the oxygen supply means 125 are stopped.

[1-2. motion]
The operation and action of the water electrolysis system 180 of the present embodiment configured as described above will be described below with reference to FIGS. 2 to 14. FIG.

In FIGS. 3 to 14, a black triangle representing a valve indicates an open state, and a white triangle representing a valve indicates a closed state.

The operation of the water electrolysis system 180 consists of three modes: operation mode, shutdown mode, and stop mode.

First, the operation mode will be explained.

[1-2-1. operation mode operation]
FIG. 2 is a flow chart showing the operation of water electrolysis system 180 in this embodiment. The operation mode consists of steps S101 to S106 in the flow chart of FIG.

3 shows the state immediately after execution of S101 in the flow chart of FIG. 2 in the water electrolysis system 180, FIG. 4 shows the state immediately after execution of S102 in the flow chart of FIG. FIG. 6 shows a state immediately after execution of S103 in the flow chart of FIG. 2 in the water electrolysis system 180, and FIG. 6 shows a state immediately after execution of S104 in the flow chart of FIG.

The operations and effects of each step will be described below with reference to FIG. 2 and FIGS. 3 to 6. FIG.

First, controller 130 opens cathode inlet valve 150, cathode outlet valve 151, and anode outlet valve 155, as shown in FIG. Further, the anode inlet switching valve 154 is opened so that the alkaline aqueous solution outlet of the anode aqueous solution supply means 122 communicates with the anode inlet 110 and the oxygen outlet of the oxygen supply means 125 does not communicate with the anode inlet 110 (S101).

Next, the controller 130 operates the cathode aqueous solution supply means 121, the cathode pH adjustment means 123, the anode aqueous solution supply means 122, and the anode pH adjustment means 124, as shown in FIG.

As a result, on the cathode 102 side, the alkaline aqueous solution controlled to a predetermined pH by the cathode pH adjusting means 123 is supplied from the cathode aqueous solution supply means 121 to the cathode inlet 107 via the cathode supply path 141, and supplied to the cathode inlet 107. The alkaline aqueous solution thus obtained flows through the cathode channel 109 toward the cathode outlet 108, and the alkaline aqueous solution discharged from the cathode outlet 108 to the cathode discharge path 142 returns to the cathode aqueous solution supply means 121 and is supplied to the cathode inlet 107 again. be.

Further, on the anode 103 side, the alkaline aqueous solution controlled to a predetermined pH by the anode pH adjusting means 124 is supplied from the anode aqueous solution supplying means 122 to the anode inlet 110 through the anode supply path 143, and supplied to the anode inlet 110. The aqueous alkaline solution flows through the anode channel 112 toward the anode outlet 111, and the aqueous alkaline solution discharged from the anode outlet 111 to the anode discharge path 144 returns to the aqueous anode solution supply means 122 and is supplied to the anode inlet 110 again. (S102).

In this embodiment, a potassium hydroxide aqueous solution is used as the alkaline aqueous solution supplied from the cathode aqueous solution supply means 121 to the cathode inlet 107 . A potassium hydroxide aqueous solution is used as the alkaline aqueous solution supplied from the anode aqueous solution supply means 122 to the anode inlet 110 .

The alkaline aqueous solution supplied from the cathode aqueous solution supply means 121 to the cathode inlet 107 is controlled by the cathode aqueous solution supply means 121 and the cathode pH adjustment means 123 so that the temperature is 75° C., the pH is 14, and the flow rate is 150 cc/min. It is regulated (controlled).

The alkaline aqueous solution supplied from the anode aqueous solution supply means 122 to the anode inlet 110 is controlled by the anode aqueous solution supply means 122 and the anode pH adjustment means 124 so that the temperature is 75° C., the pH is 14, and the flow rate is 150 cc/min. It is regulated (controlled).

Next, the controller 130 opens the hydrogen inlet valve 152, the hydrogen outlet valve 153, the oxygen inlet valve 156, and the oxygen outlet valve 157, as shown in FIG. 5 (S103).

Then, as shown in FIG. 6, the controller 130 operates the power source 128 to supply a predetermined amount of current (1.0 A/cm ² ) from the anode 103 to the cathode 102 via the diaphragm 101 . Flow (S104).

This operation causes a reduction reaction in which water becomes hydrogen and hydroxide ions at the cathode 102 as shown in Chemical Formula 1, and at the anode 103 the hydroxide ions are converted into oxygen and water as shown in Chemical Formula 2. Oxidation reaction occurs.

Hydrogen and oxygen are generated at the cathode 102 and the anode 103 of the water electrolysis device 100 by the electrochemical reactions shown in (Chem. 1) and (Chem. 2), respectively.

At this time, the cathode aqueous solution supply means 121 gas-liquid separates the hydrogen and the alkaline aqueous solution discharged from the cathode outlet 108 to the cathode discharge path, and the separated alkaline aqueous solution is controlled to a predetermined pH by the cathode pH adjusting means 123. The separated hydrogen is discharged to the hydrogen discharge path 145 (supplied to the hydrogen storage chamber 126 via the hydrogen discharge path 145).

Further, the anode aqueous solution supply means 122 gas-liquid separates the oxygen and the alkaline aqueous solution discharged from the anode outlet 111 to the anode discharge path 144, and the separated alkaline aqueous solution is controlled to a predetermined pH by the anode pH adjusting means. The separated oxygen is discharged to the oxygen discharge path 146 (supplied to the oxygen storage chamber 127 via the oxygen discharge path 146).

Next, the controller 130 confirms whether or not a stop mode instruction has been entered (S105). As a result of the confirmation in S105, if the stop mode instruction is not entered, the current state is continued for a predetermined time (10 minutes) (S106), and the process returns to S105. As a result of the confirmation in S105, if there is an instruction for the stop mode, it is determined that the operation mode has ended, and the shutdown mode (S107) is entered. Next, the fall mode will be explained.

[1-2-2. Operation in shutdown mode]
The shutdown mode consists of steps S107 to S110 in the flow chart of FIG.

7 shows the state immediately after execution of S107 in the flow chart of FIG. 2 in the water electrolysis system 180, FIG. 8 shows the state immediately after execution of S108 in the flow chart of FIG. FIG. 10 shows a state immediately after execution of S109 in the flow chart of FIG. 2 in the water electrolysis system 180, and FIG. 10 shows a state immediately after execution of S110 in the flow chart of FIG.

In the shutdown mode, first, as shown in FIG. 7, the controller 130 causes the power supply 128 to gradually reduce the current flowing through the water electrolysis device 100 until it reaches zero, and then stop. Further, the pH of the alkaline aqueous solution supplied to the anode 103 is gradually lowered to a predetermined pH (11) by the anode aqueous solution supplying means 122 and the anode pH adjusting means 124 (S107).

Next, the controller 130 closes the hydrogen inlet valve 152, the hydrogen outlet valve 153, the oxygen inlet valve 156, and the oxygen outlet valve 157, as shown in FIG. 8 (S108).

Then, as shown in FIG. 9, the controller 130 stops the cathode aqueous solution supply means 121, the cathode pH adjustment means 123, the anode aqueous solution supply means 122, and the anode pH adjustment means 124 (S109).

Subsequently, as shown in FIG. 10, the controller 130 closes the cathode inlet valve 150, the cathode outlet valve 151, the anode inlet switching valve 154, and the anode outlet valve 155 (S110), and shifts to the stop mode (S111). .

[1-2-3. Operation in stop mode]
The stop mode consists of steps S111 to S121 in the flow chart of FIG.

11 shows the state immediately after execution of S114 in the flow chart of FIG. 2 in the water electrolysis system 180, FIG. 12 shows the state immediately after execution of S115 in the flow chart of FIG. FIG. 14 shows the state immediately after execution of S119 in the flow chart of FIG. 2 in the water electrolysis system 180, and FIG. 14 shows the state immediately after execution of S120 in the flow chart of FIG.

In the stop mode, the controller 130 first measures the anode potential with the voltmeter 129 (S111), and confirms whether the anode potential has become less than a predetermined potential (500 mV) (S112).

As a result of checking in S112, if the anode potential is not less than the predetermined potential (500 mV), the current state is continued for a predetermined time (10 minutes) (S113), and the process returns to S111. As a result of confirmation in S112, if the anode potential is less than 500 mV, the process proceeds to S114.

Next, the controller 130 opens the anode inlet switching valve 154, the anode outlet valve 155, the oxygen inlet valve 156, and the oxygen supply valve 158, as shown in FIG. 11 (S114).

At this time, the anode inlet switching valve 154 allows the alkaline aqueous solution outlet of the anode aqueous solution supply means 122 to communicate with the anode inlet 110 and the oxygen outlet of the oxygen supply means 125 to communicate with the anode inlet 110 (the anode inlet switching valve 154 open so that two inlets communicate with one outlet in the anode inlet switching valve 154).

Then, as shown in FIG. 12, the controller 130 causes the anode aqueous solution supply means 122, the anode pH means 120, and the oxygen supply means 125 to generate a multi-phase flow of alkaline aqueous solution (potassium hydroxide aqueous solution) and oxygen under predetermined conditions. , to the anode 103 for a predetermined time (10 minutes) (S115).

At this time, the alkaline aqueous solution controlled to a predetermined pH by the anode pH adjustment means 124 is discharged from the anode aqueous solution supply means 122 to the anode supply path 143, and the oxygen supply means 125 removes the oxygen in the oxygen storage chamber 127 from the oxygen supply path. It flows into the anode inlet switching valve 154 from 147 and is mixed with the alkaline aqueous solution flowing through the anode supply path 143 .

Then, a mixed-phase flow of the alkaline aqueous solution and oxygen under predetermined conditions is supplied from the anode supply path 143 to the anode inlet 110, and the mixed-phase flow of the alkaline aqueous solution and oxygen supplied to the anode inlet 110 flows toward the anode outlet 111 as the anode flow. It flows through channel 112 and is discharged from anode outlet 111 to anode discharge channel 144 .

The anode aqueous solution supply means 122 gas-liquid separates the oxygen and the alkaline aqueous solution discharged from the anode outlet 111 to the anode discharge path 144, and the alkaline aqueous solution after separation is controlled to a predetermined pH by the anode pH adjusting means and is recycled. The separated oxygen is supplied to the oxygen storage chamber 127 via the oxygen discharge path 146 .

At this time, the mixed phase flow of the alkaline aqueous solution and oxygen supplied to the anode 103 for a predetermined time (10 minutes) is adjusted by the anode pH adjusting means 124, the anode aqueous solution supplying means 122, and the oxygen supplying means 125 to the volume of the alkaline aqueous solution and oxygen. The ratio is 1:2, the temperature is 75° C., the pH is 9, and the total flow rate is adjusted (controlled) to 450 cc/min.

Subsequently, the controller 130 measures the anode potential with the voltmeter 129 (S116), and confirms whether the anode potential exceeds a predetermined potential (600 mV) (S117).

As a result of checking in S117, if the anode potential does not exceed 600 mV, the current state is continued for a predetermined time (10 minutes) (S118), and the process returns to S116. As a result of checking in S117, if the anode potential exceeds 600 mV, the process proceeds to S118.

Next, as shown in FIG. 13, the controller 130 stops the anode aqueous solution supply means 122, the anode pH means 120 and the oxygen supply means 125 (S119).

Then, as shown in FIG. 14, the controller 130 closes the anode inlet switching valve 154, the anode outlet valve 155, the oxygen inlet valve 156, and the oxygen supply valve 158 (S120).

Next, the controller 130 checks whether an instruction to restart the operation mode has been received (S121). As a result of checking in S121, if there is an instruction to restart the operation mode, the process returns to S101. As a result of checking in S121, if there is no instruction to restart the operation mode, the operation of the water electrolysis system 180 is terminated.

(Example 1)
In Example 1, the flow chart shown in FIG. 2 was repeated 10 times using the water electrolysis system 180 of Embodiment 1 shown in FIG. 1, and the energy efficiency before and after the cycle test was evaluated.

As a result, as shown in Table 1 below, no significant decrease in energy efficiency was confirmed after the cycle test.

(Comparative example 1)
In Comparative Example 1, the water electrolysis system 180 of Embodiment 1 shown in FIG. 1 is used, and after continuing S110 in the flowchart shown in FIG. Energy efficiency was evaluated after repeating the same flow chart as in Example 1 10 times except for performing the above.

As a result, as shown in (Table 1) below, a significant decrease in energy efficiency due to the cycle test was confirmed. After the cycle test, the water electrolysis device 100 was disassembled and the anode catalyst layer was observed with a transmission electron microscope (TEM). As a result, peeling of the anode catalyst from the anode substrate was observed.

From the above water electrolysis test, it was confirmed that the water electrolysis system 180 of Example 1 has high cycle test resistance.

[1-3. effects, etc.]
As described above, in the method for suppressing anode deterioration of a water electrolysis device according to the present embodiment, the diaphragm-electrode assembly 104 in which the hydroxide ion conductive diaphragm 101 is sandwiched between the cathode 102 and the anode 103 is connected to the cathode separator 105. and the anode separator 106 to suppress deterioration of the anode 103 of the water electrolysis device 100 .

The cathode 102 has a structure in which a catalyst for causing a reductive reaction in which water becomes hydrogen and hydroxide ions is supported on an electron-conducting substrate. The anode 103 has a structure in which a catalyst for causing an oxidation reaction to generate oxygen and water from hydroxide ions is supported on an electron conductive substrate.

The cathode separator 105 is formed on the surface where the cathode channel 109 faces the cathode 102 . The anode separator 106 is formed on the surface where the anode channel 112 faces the anode 103 .

Then, the method for suppressing anode deterioration of a water electrolysis device of the present embodiment shifts from the operation mode in which hydrogen and oxygen are produced in the water electrolysis device 100 to the stop mode in which the production of hydrogen and oxygen in the water electrolysis device 100 is stopped. It is characterized by suppressing deterioration of the anode 103 by subsequently supplying a mixed-phase flow of an alkaline aqueous solution and oxygen to the anode channel 112 (anode 103).

As a result, after the operation mode is shifted to the stop mode, the multiphase flow containing the alkaline aqueous solution and oxygen is supplied to the anode 103. Therefore, in the step of stopping the production of hydrogen, the potential change of the anode 103 causes the anode 103 It is possible to suppress the structural change and alteration of Therefore, deterioration of the anode 103 can be suppressed.

As in the present embodiment, the method for suppressing anode deterioration of a water electrolysis device is such that the voltage between the cathode 102 and the anode 103 or the potential of the anode 103 becomes smaller than the specified value after the operation mode is shifted to the stop mode. In this case, a mixed phase flow of alkaline aqueous solution and oxygen may be supplied to the anode channel 112 (anode 103).

As a result, it is possible to suppress the structural change and deterioration of the anode 103 occurring when the potential of the anode 103 becomes lower than the specified value at an appropriate timing. Therefore, deterioration of the anode 103 can be suppressed at a more appropriate timing.

As in the present embodiment, the method for suppressing anode deterioration of a water electrolysis device is such that the pH value of the alkaline aqueous solution when supplying the mixed-phase flow of the alkaline aqueous solution and oxygen to the anode channel 112 (anode 103) is set to the operation mode It may be lower than the pH value of the alkaline aqueous solution supplied to the water electrolysis device 100 at times.

As a result, the anode 103 can be held at a high potential, and structural change and deterioration of the anode 103 can be further suppressed. Therefore, deterioration of the anode 103 can be further suppressed.

As in the present embodiment, the method for suppressing anode deterioration of a water electrolysis device is such that when the water electrolysis device 100 shifts from the operation mode to the shutdown mode via the shutdown mode, the cathode 102 and the anode 103 are separated in the shutdown mode. The pH of the alkaline aqueous solution supplied to the anode 103 may be adjusted such that the current supplied during the period is gradually decreased and the pH value of the alkaline aqueous solution supplied to the anode 103 is gradually decreased.

As a result, in the fall mode, the anode can be held at a high potential, and structural change and deterioration of the anode 103 can be suppressed. Therefore, deterioration of the anode 103 in the fall mode can be suppressed.

As in the present embodiment, the method for suppressing anode deterioration of a water electrolysis device starts supplying a multiphase flow containing an alkaline aqueous solution and oxygen to the anode 103, and then, when a predetermined condition is satisfied, the multiphase flow flows to the anode 103. supply may be stopped.

As a result, when hydrogen and oxygen are not produced in the water electrolysis device 100, the anode aqueous solution supply means 122 and the oxygen supply means 125 continue the supply operation more than necessary, and the anode aqueous solution supply means 122 and the oxygen supply means 125 continue to operate. It is possible to prevent wasteful consumption of the electrical energy required to operate the .

(Other embodiments)
As described above, Embodiment 1 has been described as an example of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments with modifications, additions, omissions, and the like. Also, it is possible to combine the constituent elements described in the first embodiment to form a new embodiment.

Therefore, other embodiments will be exemplified below.

In Embodiment 1, a plurality of water electrolysis devices 100 may be stacked in series. As a result, it is possible to suppress the deterioration of the anode 103 (especially the deterioration of the anode 103 due to the reverse current) which is accelerated by stacking.

Further, when the water electrolysis device 100 is configured so that the alkaline aqueous solution supplied to either the cathode 102 or the anode 103 is also supplied to the other of the cathode 102 and the anode 103, the alkaline aqueous solution supply means is You can make one.

In the case of using only one alkaline aqueous solution supply means, it is possible to simplify the stack and reduce the short-circuit paths of hydroxide ions in the stack. deterioration of the anode 103 due to current) can be suppressed.

Further, when the potential of the cathode 102 reaches a specified value after the operation mode is shifted to the stop mode, if the mixed phase flow of the alkaline aqueous solution and hydrogen is supplied to the cathode 102, the potential of the cathode 102 is Degradation of the cathode 102 due to the change can be suppressed.

INDUSTRIAL APPLICABILITY The present disclosure is applicable to, for example, a water electrolysis system that electrolyzes water contained in an alkaline aqueous solution to produce hydrogen and oxygen using a water electrolysis device that includes a diaphragm-electrode assembly.

REFERENCE SIGNS LIST 100 water electrolysis device 101 diaphragm 102 cathode 103 anode 104 diaphragm-electrode assembly 105 cathode separator 106 anode separator 107 cathode inlet 108 cathode outlet 109 cathode channel 110 anode inlet 111 anode outlet 112 anode channel 121 cathode aqueous solution supply means 122 anode aqueous solution Supply means 123 Cathode pH adjustment means 124 Anode pH adjustment means 125 Oxygen supply means 126 Hydrogen storage chamber 127 Oxygen storage chamber 128 Power source 129 Voltmeter 130 Controller 141 Cathode supply path 142 Cathode discharge path 143 Anode supply path 144 Anode discharge path 145 Hydrogen Exhaust route 146 Oxygen discharge route 147 Oxygen supply route 150 Cathode inlet valve 151 Cathode outlet valve 152 Hydrogen inlet valve 153 Hydrogen outlet valve 154 Anode inlet switching valve 155 Anode outlet valve 156 Oxygen inlet valve 157 Oxygen outlet valve 158 Oxygen supply valve 180 Water electrolysis system

Claims (5)

Electrons are the catalyst for causing the oxidation reaction that produces oxygen and water from the cathode, which is supported on an electron-conductive base material, and the catalyst for causing the reduction reaction in which water becomes hydrogen and hydroxide ions. A cathode separator having a cathode flow channel formed on the surface facing the cathode, and an anode flow A method for suppressing deterioration of the anode of a water electrolysis device in which a channel is sandwiched between the anode and an anode separator formed on the surface facing the anode, comprising:
After shifting from the operation mode in which hydrogen and oxygen are produced in the water electrolysis device to the stop mode in which the production of hydrogen and oxygen in the water electrolysis device is stopped, a mixed phase flow of an alkaline aqueous solution and oxygen is supplied to the anode flow channel. A method for suppressing deterioration of an anode in a water electrolysis device, comprising: supplying the multiphase flow to the anode channel when the voltage between the cathode and the anode or the potential of the anode becomes smaller than a specified value after the operation mode is shifted to the stop mode; Item 2. The method for suppressing anode deterioration of a water electrolysis device according to item 1. 3. The method according to claim 1, wherein the pH value of the alkaline aqueous solution when the multiphase flow is supplied to the anode channel is set lower than the pH value of the alkaline aqueous solution supplied to the water electrolysis device during the operation mode. and a method for suppressing anode deterioration in a water electrolysis device. When shifting from the operation mode to the stop mode via the shutdown mode,
In the shutdown mode, the current flowing between the cathode and the anode is gradually decreased, and the pH value of the alkaline aqueous solution supplied to the anode flow channel is gradually lowered. 4. The method for suppressing anode deterioration of a water electrolysis device according to any one of claims 1 to 3, wherein the pH of the alkaline aqueous solution to be supplied is adjusted. 5. The water according to any one of claims 1 to 4, wherein the supply of the multiphase flow to the anode flow channel is stopped when a predetermined condition is satisfied after starting the supply of the multiphase flow to the anode flow channel. A method for suppressing anode deterioration of an electrolytic device.

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