AU2023201239B2 - Electrolysis device and electrolysis method - Google Patents

Abstract

An electrolysis device (1) comprising: an electrolysis cell (2) including and cathode (24), anode (28), diaphragm (29); a supply power property obtaining unit (4) that obtains a property of power that is to be supplied to the electrolysis cell; an input gas property obtaining unit (6) that obtains a property of a gas that is to be input to the electrolysis cell; an electric property obtaining unit (7) that obtains an electric property of the electrolysis cell; an output gas property obtaining unit (8) that obtains a property of an output gas of the electrolysis cell; a temperature control unit (9) that controls a temperature of the electrolysis cell; a temperature obtaining unit (10) that obtains the temperature of the electrolysis cell; a data storage unit (11) that stores data from the supply power property obtaining unit (4), the input gas property obtaining unit (6), the electric property obtaining unit (7), the output gas property obtaining unit (8), and the temperature obtaining unit (10); and a data processing unit (12) to which the data is sent from the data storage unit and that processes the data to determine a state of the electrolysis cell (2). 1/12 z CC < D -J U 00 F-0 CU< -

Description

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- ELECTROLYSIS DEVICE AND ELECTROLYSIS METHOD FIELD

[0001] Arrangements disclosed herein relate to an electrolysis device and an

electrolysis method.

BACKGROUND

[0002] There has been a concern about the depletion of fossil fuels such as petroleum

and coal, and expectations are increasing for sustainable renewable energy. Examples of

the renewable energy include those by solar power generation, hydroelectric power

generation, wind power generation, and geothermal power generation. The amount of

powers generated by these depends on weather, nature conditions, and so on and thus they

are power sources whose outputs vary (variable power sources) and have a problem of

difficulty in stably supplying the power. In light of this, it has been attempted to adjust

power by combining a variable power source and a storage battery. Storing the power,

however, has problems of the cost of the storage battery and loss during the power storage.

[0003] Also drawing attention as decarbonization attempts are: water electrolysis

technology that electrolyzes water (H 20) to produce hydrogen (H 2); and carbon dioxide

electrolysis technology that electrolyzes carbon dioxide (C02) and electrochemically

reduces it to convert it to a chemical substance (chemical energy) such as a carbon

compound such as carbon monoxide (CO), formic acid (HCOOH), methanol (CH30H),

methane (CH 4 ), acetic acid (CH3COOH), ethanol (C 2H 5 0H), ethane (C 2H 6 ), or ethylene

(C 2H 4). Connecting a variable power source that uses renewable energy to such an

electrolysis device is advantageous in that power adjustment and hydrogen production, and

carbon dioxide recycling are achieved at the same time.

[0004] As a carbon dioxide electrolysis device, a structure is under consideration, for

example, in which a catholyte and a C02 gas are in contact with a cathode and an anolyte 1

21586185_1(GHMatters) P121160.AU is in contact with an anode. Such a structure will be called a carbon dioxide electrolysis cell here. For example, if a reaction of producing, for example, CO from C02 is caused for a long time using such an electrolysis cell by passing a constant current to the cathode and the anode, there arise problems of time-dependent deterioration in cell output such as a decrease in the amount of CO produced and an increase in cell voltage. One example of the deterioration is a phenomenon that salt originating in an electrolyte of the solution precipitates in a gas channel to obstruct the flow of the gas or the like, against which the introduction of a refresh operation to dissolve the salt is under consideration.

[0005] However, it is becoming clear that the electrolysis device of carbon dioxide

(C0 2) or the like undergoes various deterioration phenomena in addition to the

phenomenon of the precipitation of salt in the channel. Further, an electrolysis device of,

for example, nitrogen (N 2 ) undergoes a deterioration phenomenon unique to N 2

electrolysis, in addition to the same deterioration phenomena as that in the C02

electrolysis. This necessitates appropriately setting a determination standard according to

the types of an electrolyte and deterioration, such as continuing the operation or executing

a work of stopping the operation and performing the maintenance of the electrolysis cell

according to an electrolyte or a deteriorated place. Therefore, it is required to determine

cell states such as the state and type of the deterioration of the electrolysis cell.

SUMMARY

[0006] Accordingly, there is a need to provide an electrolysis device and an

electrolysis method that enable the determination of the state of an electrolysis cell.

[0007] According to arrangements of the present invention, an electrolysis device and

an electrolysis method that enable the determination of the state of an electrolysis cell are

provided.

[007A] The present invention provides an electrolysis device comprising:

2

21586185_1 (GHMatters) P121160.AU an electrolysis cell including a cathode part to be supplied with a gas or a liquid containing a substance to be reduced and in which a reduction electrode is disposed, an anode part to be supplied with a liquid containing a substance to be oxidized and in which an oxidation electrode is disposed, and a diaphragm provided between the cathode part and the anode part; a supply power property obtaining unit that obtains a property of power that is to be supplied to the electrolysis cell; an input gas property obtaining unit that obtains a property of a gas that is to be input to the electrolysis cell; an electric property obtaining unit that obtains an electric property of the electrolysis cell; an output gas property obtaining unit that obtains a property of an output gas of the electrolysis cell; a temperature control unit that controls a temperature of the electrolysis cell; a temperature obtaining unit that obtains the temperature of the electrolysis cell; a data storage unit that stores data from the supply power property obtaining unit, the input gas property obtaining unit, the electric property obtaining unit, the output gas property obtaining unit, and the temperature obtaining unit; a data processing unit to which the data is sent from the data storage unit and that processes the data to obtain an equivalent circuit model and an equivalent circuit parameter of the electrolysis cell and determine a state of the electrolysis cell using the equivalent circuit model and the equivalent circuit parameter of the electrolysis cell; and a display unit that displays information including the equivalent circuit model, the equivalent circuit parameter, and the determined state.

[007B] The present invention provides an electrolysis method comprising:

supplying a gas or a liquid containing a substance to be reduced to a cathode part

of an electrolysis cell, supplying a liquid containing a substance to be oxidized to an anode 3

21586185_1 (GHMatters) P121160.AU part of the electrolysis cell, and operating the electrolysis cell, the electrolysis cell including the cathode part in which a reduction electrode is disposed, the anode part in which an oxidation electrode is disposed, and a diaphragm provided between the cathode part and the anode part; obtaining property data of power that is to be supplied to the electrolysis cell, property data of a gas that is to be input to the electrolysis cell, electric property data of the electrolysis cell, property data of an output gas of the electrolysis cell, and temperature data of the electrolysis cell, all the data being obtained during the operation of the electrolysis cell; processing the property data of the power, the property data of the gas, the electric property data, the property data of the output gas, and the temperature data to obtain an equivalent circuit model and an equivalent circuit parameter of the electrolysis cell, and determining a state of the electrolysis cell, using the equivalent circuit model and the equivalent circuit parameter of the electrolysis cell; and displaying information including the equivalent circuit model, the equivalent circuit parameter, and the determined state.

BRIEF DESCRIPTION OF THE DRAWINGS

[007C] In order that the invention may be more clearly ascertained, embodiments will

now be described by way of example with reference to the accompanying drawings in

which:

[0008] FIG. 1 is a diagram illustrating an electrolysis device of an arrangement.

[0009] FIG. 2 is a view illustrating an electrolysis cell in a carbon dioxide electrolysis

device of a first arrangement.

[00101 FIG. 3 is a chart illustrating a deterioration detection process by the carbon

dioxide electrolysis device of the first arrangement.

[0011] FIG. 4 is a diagram illustrating an equivalent circuit model of the electrolysis 4

21586185_1 (GHMatters) P121160.AU cell in the carbon dioxide electrolysis device of the first arrangement.

[0012] FIG. 5 is a table illustrating equivalent circuit parameters of the equivalent

circuit model illustrated in FIG. 4.

[0013] FIG. 6 is a view illustrating an electrolysis cell in a carbon dioxide electrolysis

device of a second arrangement.

[0014] FIG. 7 is a diagram illustrating an equivalent circuit model of an electrolysis

cell in a carbon dioxide electrolysis device of a third arrangement.

[0015] FIG. 8 is a table illustrating equivalent circuit parameters of the equivalent

circuit model illustrated in FIG. 7.

[0016] FIG. 9 is a diagram illustrating an equivalent circuit model of an electrolysis

cell in a nitrogen electrolysis device of a fourth arrangement.

[0017] FIG. 10 is a chart illustrating a design process of an electrolysis device

according to a fifth arrangement.

[0018] FIG. 11 is a chart illustrating measurement data and simulation data of CO part

current density Jco and H 2 part current density JH2 according to Example 1.

[0019] FIG. 12 is a chart illustrating measurement data and simulation data of cell

voltage Vce, cathode potential Vc, and anode potential Vai according to Example 1.

[0020] FIG. 13 is a chart illustrating measurement data and simulation data of CO

Faraday efficiency FEco and H2 Faraday efficiency H2 according to Example 1.

[0021] FIG. 14 is a chart illustrating measurement data and simulation data of cathode

output gases (CO, H 2 , and CO 2) according to Example 1.

[0022] FIG. 15 is a chart illustrating measurement data and simulation data of anode

output gases (02 and C0 2 ) according to Example 1.

DETAILED DESCRIPTION OF EMBODIMENTS

[0023] An electrolysis device of an arrangement include: an electrolysis cell including

a cathode part to be supplied with a gas or a liquid containing a substance to be reduced 5

21586185_1 (GHMatters) P121160.AU and in which a reduction electrode is disposed, an anode part to be supplied with a liquid containing a substance to be oxidized and in which an oxidation electrode is disposed, and a diaphragm provided between the cathode part and the anode part; a supply power property obtaining unit that obtains a property of power that is to be supplied to the electrolysis cell; an input gas property obtaining unit that obtains a property of a gas that is to be input to the electrolysis cell; an electric property obtaining unit that obtains an electric property of the electrolysis cell; an output gas property obtaining unit that obtains a property of an output gas of the electrolysis cell; a temperature control unit that controls a temperature of the electrolysis cell; a temperature obtaining unit that obtains the temperature of the electrolysis cell; a data storage unit that stores data from the supply power property obtaining unit, the input gas property obtaining unit, the electric property obtaining unit, the output gas property obtaining unit, and the temperature obtaining unit; and a data processing unit to which the data is sent from the data storage unit and that processes the data to determine a state of the electrolysis cell.

[0024] Electrolysis devices and electrolysis methods of arrangements will be

hereinafter described with reference to the drawings. In the arrangements below,

substantially the same constituent parts are denoted by the same reference signs and a

description thereof may be partly omitted. The drawings are schematic, and the relation

of thickness and planar dimension, a thickness ratio among parts, and so on may be

different from actual ones.

[0025] FIG. 1 is a diagram illustrating an electrolysis device 1 of an arrangement.

The electrolysis device 1 illustrated in FIG. 1 includes an electrolysis cell 2; a supply

power control unit 3 that controls power that is to be supplied to the electrolysis cell 2; a

supply power property obtaining unit 4 that obtains the properties of the supply power; a

gas/electrolysis solution control unit 5 that controls a gas and an electrolysis solution that

are to be supplied to the electrolysis cell 2; an input gas property obtaining unit 6 that

obtains the properties of the input gas that is to be supplied; an electric property obtaining 6

21586185_1 (GHMatters) P121160.AU unit 7 that obtains the electric properties of the electrolysis cell 2; an output gas property obtaining unit 8 that obtains the properties of an output gas of the electrolysis cell 2; a temperature control unit 9 that controls the temperature of the electrolysis cell 2; a temperature obtaining unit 10 that obtains the temperature of the electrolysis cell 2; a data storage unit 11 that stores data from the supply power property obtaining unit 4, the input gas property obtaining unit 6, the electric property obtaining unit 7, the output gas property obtaining unit 8, and the temperature obtaining unit 10; a data processing unit 12 to which the data is transmitted from the data storage unit 11 and that processes the transmitted data; and a display unit 13. These parts will be described in detail below.

[0026] The electrolysis cell 2, which has a structure appropriate for a substance that is

to be electrolyzed by the electrolysis device 1, includes at least a reduction electrode

chamber that is supplied with a gas or a liquid containing a substance to be reduced and in

which a reduction electrode is disposed, an oxidation electrode chamber that is supplied

with a liquid containing a substance to be oxidized and in which an oxidation electrode is

disposed, and a diaphragm provided between the reduction electrode chamber and the

oxidation electrode chamber. Examples of the substance that is to be electrolyzed by the

electrolysis device 1 include carbon dioxide (C0 2), nitrogen (N 2 ), and water (H20).

Through the electrolysis and reduction of C02, a carbon compound such as carbon

monoxide (CO), formic acid (HCOOH), methane (CH4), methanol (CH30H), ethane

(C 2 H 6), ethylene (C 2 H4), ethanol (C 2 H50H), formaldehyde (HCHO), or ethylene glycol

(C2H602) is produced. At the same time with the reduction reaction of C02, hydrogen

(H 2) is sometimes produced through a reduction reaction of H 20. In the case where N 2 is

electrolyzed to be reduced, ammonia (NH 3 ) is produced.

[0027] (First Arrangement)

As a first arrangement, an electrolysis device 1 of carbon dioxide (C0 2) will be

described with reference to FIG. 1 and FIG. 2. As illustrated in FIG. 2, out of the

electrolysis cell 2 illustrated in FIG. 1, an electrolysis cell 2 (2A) for electrolyzing C02 7

21586185_1 (GHMatters) P121160.AU includes a cathode part (reduction electrode chamber) 24 having a first storage part

(storage tank) 22 for storing a first electrolysis solution 21 containing CO2 and a reduction

electrode (cathode) 23 disposed in the first storage part 22, an anode part (oxidation

electrode chamber) 28 having a second storage part (storage tank) 26 for storing a second

electrolysis solution 25 containing water and an oxidation electrode (anode) 27 disposed in

the second storage part 26, and a diaphragm 29 disposed between the first storage part 22

and the second storage part 26. The first storage part 22, the second storage part 26, and

the diaphragm 29 form a reaction tank 30.

[0028] The reaction tank 30 is divided into two chambers, the first storage part 22 and

the second storage part 26, by the diaphragm 29 allowing ions such as hydrogen ions (H+),

hydroxide ions (OH-), hydrogen carbonate ions (HCO3-), and carbonate ions (CO3-) to

move therethrough. The reaction tank 30 may be formed of, for example, a white quartz

glass plate, an acrylic resin (PMMA), polystyrene (PS), or the like. The reaction tank 30

may be partly formed of a light-transmitting material and the other part thereof may be

formed of a resin material. Examples of the resin material include polyether ether ketone

(PEEK), polyamide (PA), polyvinylidene fluoride (PVDF), polyacetal (POM) (copolymer),

polyphenylene ether (PPE), an acrylonitrile-butadiene-styrene copolymer (ABS),

polypropylene (PP), and polyethylene (PE).

[0029] In the first storage part 22, the reduction electrode 23 is disposed and CO2 is

further stored. In the first storage part 22, CO 2 is stored, for example, as the first

electrolysis solution 21 containing the same. The first electrolysis solution 21 functions

as a reduction electrode solution (catholyte) and contains carbon dioxide (C02) as the

substance to be reduced. Here, C02 present in the first electrolysis solution 21 need not

be gaseous and may be in a dissolved form or may be in the form of carbonate ions

(C0 32-), hydrogen carbonate ions (HCO3-), or the like. The first electrolysis solution 21

may contain hydrogen ions, and it is preferably an aqueous solution. In the second

storage part 26, the oxidation electrode 27 is disposed and the second electrolysis solution 8

21586185_1 (GHMatters) P121160.AU

25 containing water is further stored. The second electrolysis solution 25 functions as an

oxidation electrode solution (anolyte) and contains, as the substance to be oxidized, water

(H20), chloride ions (Cl-), carbonate ions (CO32-), hydrogen carbonate ions (HCO3-), or the

like, for instance. The second electrolysis solution 25 may be an alcohol aqueous solution

or an aqueous solution of an organic substance such as amine.

[0030] Varying the amounts of water contained in the first and second electrolysis

solutions 21, 25 or changing the electrolysis solution components can change reactivity to

change the selectivity of the substance to be reduced or a ratio of produced chemical

substances. The first and second electrolysis solutions 21, 25 may contain a redox couple

as required. Examples of the redox couple include Fe3+/Fe2+ and 10 3 -/1-. The first

storage part 22 is connected to a gas supply channel 31 that supplies a source gas

containing C02 and a first solution supply channel 32 that supplies the first electrolysis

solution 21 and is further connected to a first gas and solution discharge channel 33 that

discharges a reaction gas and the first electrolysis solution 21. The second storage part 26

is connected to a second solution supply channel 34 that supplies the second electrolysis

solution 25 and is further connected to a second gas and solution discharge channel 35.

The first and second storage parts 22, 26 may each have a space for storing gases contained

in a reactant and a product.

[0031] The pressures in the first and second storage parts 22, 26 are preferably set to

pressures at which C02 does not liquefy. Specifically, their pressures are preferably

adjusted to, for example, a range of not lower than 0.1 MPa nor higher than 6.4 MPa. If

the pressures in the storage parts 22, 26 are lower than 0.1 MPa, the efficiency of the C02

reduction reaction may decrease. If the pressures in the storage parts 22, 26 exceed 6.4

MPa, C02 liquefies, and the efficiency of the C02 reduction reaction may decrease. A

differential pressure between the first storage part 22 and the second storage part 26 may

cause the breakage or the like of the diaphragm 29. Therefore, the difference between the

pressures of the first storage part 22 and the second storage part 26 (differential pressure) is 9

21586185_1 (GHMatters) P121160.AU preferably 1 MPa or lower.

[0032] The lower the temperatures of the electrolysis solutions 21, 25, the larger the

dissolution amount of C02, but low temperatures result in high solution resistance and a

high theoretical voltage of the reaction and thus are disadvantageous from a viewpoint of

the C02 electrolysis. On the other hand, high temperatures of the electrolysis solutions

21, 25 result in a small dissolution amount of C02 but are advantageous from a viewpoint

of the C02 electrolysis. Therefore, the operating temperature condition of the electrolysis

cell 2A is preferably in a mid-temperature range, for example, in a range of not lower than

the atmospheric temperature nor higher than the boiling points of the electrolysis solutions

21, 25. In the case where the electrolysis solutions 21, 25 are aqueous solutions, a

temperature of not lower than 10°C nor higher than 100°C is preferable and a temperature

of not lower than 25°C nor higher than 80°C is more preferable. The operation under

higher temperatures is allowed in the case where the source gas containing C02 is filled in

the first storage part 22 and water vapor is filled in the second storage part 26. In this

case, the operating temperature is decided in consideration of the heat resistance of

members such as the diaphragm 29. In the case where the diaphragm 29 is an ion

exchange membrane or the like, the maximum operating temperature is 180°C, and in the

case where the diaphragm 29 is a polymeric porous membrane such as Teflon (registered

trademark), the maximum temperature is 300°C.

[0033] The first electrolysis solution 21 and the second electrolysis solution 25 may be

electrolysis solutions containing different substances or may be the same electrolysis

solutions containing the same substance. In the case where the first electrolysis solution

21 and the second electrolysis solution 25 contain the same substance and the same

solvent, the first electrolysis solution 21 and the second electrolysis solution 25 may be

regarded as one electrolysis solution. Further, pH of the second electrolysis solution 25

may be higher than pH of the first electrolysis solution 21. This facilitates the movement

of ions such as hydrogen ions or hydroxide ions through the diaphragm 29. This also 10

21586185_1 (GHMatters) P121160.AU achieves the effective progress of the redox reaction owing to a liquid junction potential due to the pH difference.

[0034] The first electrolysis solution 21 is preferably a solution high in C02

absorptance. C02 does not necessarily have to be in a dissolved form in the first

electrolysis solution 21, and C02 in a bubble form may be mixed and present in the first

electrolysis solution 21. Examples of the electrolysis solution containing C02 include

aqueous solutions containing hydrogen carbonate or carbonate such as lithium hydrogen

carbonate (LiHCO 3), sodium hydrogen carbonate (NaHCO3), potassium hydrogen

carbonate (KHCO 3), cesium hydrogen carbonate (CsHCO3), sodium carbonate (Na2CO3),

and potassium carbonate (K 2CO 3 ), phosphoric acid, boric acid, or the like. The

electrolysis solution containing C02 may contain any of alcohols such as methanol,

ethanol, and acetone or may be an alcohol solution. The first electrolysis solution 21 may

be an electrolysis solution containing a CO2 absorbent that lowers the reduction potential

of CO2, has high ion conductivity, and absorbs CO2.

[0035] The second electrolysis solution 25 may be a solution containing water (H 2 0),

for example, an aqueous solution containing a desired electrolyte. This solution is

preferably an aqueous solution that promotes an oxidation reaction of water. Examples of

the aqueous solution containing the electrolyte include aqueous solutions containing

phosphate ions (P043-), borate ions (B033-), sodium ions (Na+), potassium ions (K+),

calcium ions (Ca2+), lithium ions (Li+), cesium ions (Cs*), magnesium ions (Mg2+),

chloride ions (Cl-), hydrogen carbonate ions (HCO3-), carbonate ions (CO32-), hydroxide

ions (OH-), or the like.

[0036] As the aforesaid electrolysis solutions 21, 25, an ionic liquid that is composed

of salt of cations such as imidazolium ions or pyridinium ions and anions such as BF4- or

PF6- and that is in a liquid form in a wide temperature range, or an aqueous solution thereof

is usable, for instance. Other examples of the electrolysis solutions include solutions of

amine such as ethanolamine, imidazole, or pyridine and aqueous solutions thereof. 11

21586185_1 (GHMatters) P121160.AU

Examples of the amine include primary amine, secondary amine, and tertiary amine.

These electrolysis solutions may be high in ion conductivity, have properties of absorbing

carbon dioxide, and have characteristics of decreasing reduction energy.

[0037] Examples of the primary amine include methylamine, ethylamine,

propylamine, butylamine, pentylamine, and hexylamine. A hydrocarbon of the amine

may be replaced by alcohol, halogen, or the like. Examples of the amine whose

hydrocarbon is replaced include methanolamine, ethanolamine, and chloromethylamine.

Further, an unsaturated bond may be present therein. The same applies to hydrocarbons

of the secondary amine and the tertiary amine.

[0038] Examples of the secondary amine include dimethylamine, diethylamine,

dipropylamine, dibutylamine, dipentylamine, dihexylamine, dimethanolamine,

diethanolamine, and dipropanolamine. The replaced hydrocarbons may be different.

This also applies to the tertiary amine. Examples of one whose hydrocarbons are

different include methylethylamine and methylpropylamine.

[0039] Examples of the tertiary amine include trimethylamine, triethylamine,

tripropylamine, tributylamine, trihexylamine, trimethanolamine, triethanolamine,

tripropanolamine, tributanolamine, triexanolamine, methyldiethylamine, and

methyldipropylamine.

[0040] Examples of the cations of the ionic liquid include 1-ethyl-3

methylimidazolium ions, 1-methyl-3-propylimidazolium ions, 1-butyl-3

methylimidazolium ions, 1-methyl-3-pentylimidazolium ions, and 1-hexyl-3

methylimidazolium ions.

[0041] The second position of the imidazolium ion may be replaced. Examples of

the cation resulting from the replacement of the second position of the imidazolium ion

include a 1-ethyl-2,3-dimethylimidazolium ion, a 1,2-dimethyl-3-propylimidazolium ion, a

1-butyl-2,3-dimethylimidazolium ion, a 1,2-dimethyl-3-pentylimidazolium ion, and a 1

hexyl-2,3-dimethylimidazolium ion. 12

21586185_1 (GHMatters) P121160.AU

[0042] Examples of the pyridinium ions include methylpyridinium, ethylpyridinium,

propylpyridinium, butylpyridinium, pentylpyridinium, and hexylpyridinium. In the

imidazolium ion and the pyridinium ion, an alkyl group may be replaced, or an unsaturated

bond may be present.

[0043] Examples of the anions include fluoride ions (F-), chloride ions (Cl-), bromide

ions (Br-), iodide ions (I-), BF 4 -, PF6-, CF 3COO-, CF 3 SO3-, NO3-, SCN-, (CF 3 SO 2 )3 C-,

bis(trifluoromethoxysulfonyl)imide, bis(trifluoroethoxysulfonyl)imide, and

bis(perfluoroethylsulfonyl)imide. The ionic liquid may be composed of dipolar ions

formed of the cations and the anions that are connected by hydrocarbons. Note that a

buffer solution such as a potassium phosphate solution may be supplied to the storage parts

22,26.

[0044] As the diaphragm 29, a membrane selectively allowing the flow of anions or

cations is used. Consequently, the electrolysis solutions 21, 25 in contact with the

reduction electrode 23 and the oxidation electrode 27 respectively can be electrolysis

solutions containing different substances. Further, it is possible to promote a reduction

reaction and an oxidation reaction owing to a difference in ionic strength, a difference in

pH, and so on. The use of the diaphragm 29 can separate the first electrolysis solution 21

and the second electrolysis solution 25 from each other. The diaphragm 29 may have a

function of allowing the permeation of part of the ions contained in the electrolysis

solutions 21, 25 in which these electrodes 23, 27 are immersed, that is, a function of

shutting off one kind of ions or more contained in the electrolysis solutions 21, 25. As a

result, the two electrolysis solutions 21, 25 can be solutions different in pH, for instance.

[0045] Examples usable as the diaphragm 29 include ion exchange membranes such as

NEOSEPTA (registered trademark) of ASTOM Corporation, SELEMION (registered

trademark) of AGC Inc., Aciplex (registered trademark) of AGC Inc., Fumasep (registered

trademark) and fumapem (registered trademark) of Fumatech BWT GmbH, Nafion

(registered trademark) of DuPont, which is a fluorocarbon resin formed of sulfonated and 13

21586185_1 (GHMatters) P121160.AU polymerized tetrafluoroethylene, lewabrane (registered trademark) of LANXESS AG,

IONSEP (registered trademark) of IONTECH Inc., Mustang (registered trademark) of

PALL Corporation, relax (registered trademark) of MEGA Co., Ltd., and GORE-TEX

(registered trademark) of W.L. Gore & Associates GmbH. The ion exchange membrane

may be formed using a membrane whose basic structure is hydrocarbons, or in the case of

anion exchange, it may be a membrane having an amine group. In the case where the

first electrolysis solution 21 and the second electrolysis solution 25 are different in pH, the

use of a bipolar membrane in which a cation exchange membrane and an anion exchange

membrane are stacked makes it possible to keep pH of the electrolysis solutions stable

when they are used.

[0046] Examples usable as the diaphragm 29 other than the ion exchange membrane

include: porous membranes of a silicone resin, a fluorine-based resin such as

perfluoroalkoxyalkane (PFA), a perfluoroethylene-propane copolymer (FEP),

polytetrafluoroethylene (PTFE), an ethylene-tetrafluoroethylene copolymer (ETFE),

polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and an ethylene

chlorotrifluoroethylene copolymer (ECTFE), polyethersulfone (PES), or ceramic; and

insulating porous bodies such as a glass filter, a filling filled with agar, zeolite, and oxide.

A hydrophilic porous membrane is preferable as the diaphragm 29 because it is not clogged

with bubbles.

[0047] The reduction electrode 23 is an electrode (cathode) that reduces carbon

dioxide (C02) to produce a carbon compound. The reduction electrode 23 is disposed in

the first storage part 22 to be immersed in the first electrolysis solution 21. The reduction

electrode 23 contains a reduction catalyst for producing the carbon compound through the

reduction reaction of C02, for instance. Examples of the reduction catalyst include a

material that lowers activation energy for reducing C02. In other words, a material that

lowers overvoltage when the carbon compound is produced through the reduction reaction

of C02 is usable.

14

21586185_1 (GHMatters) P121160.AU

[0048] As the reduction electrode 23, a metal material or a carbon material is usable,

for instance. As the metal material, metal such as gold, aluminum, copper, silver,

platinum, palladium, zinc, mercury, indium, nickel, or titanium, or an alloy containing the

aforesaid metal is usable, for instance. As the carbon material, graphene, carbon

nanotube (CNT), fullerene, ketjen black, or the like is usable, for instance. The reduction

catalyst is not limited to these, and a metal complex such as a Ru complex or a Re

complex, or an organic molecule having an imidazole skeleton or a pyridine skeleton may

be used, for instance. The reduction catalyst may be a mixture of a plurality of materials.

The reduction electrode 23 may have a structure in which the reduction catalyst in a thin

film form, a lattice form, a granular form, a wire form, or the like is provided on a

conductive base material, for instance.

[0049] The carbon compound produced through the reduction reaction in the reduction

electrode 23 differs depending on the kind of the reduction catalyst and so on, and

examples thereof include carbon monoxide (CO), formic acid (HCOOH), methane (CH4),

methanol (CH3 0H), ethane (C 2 H6 ), ethylene (C2 H4), ethanol (C 2 H5 0H), formaldehyde

(HCHO), and ethylene glycol (C 2H 60 2). The reduction electrode 23 sometimes causes a

side reaction to produce hydrogen (H 2) through a reduction reaction of water (H 20)

simultaneously with the reduction reaction of carbon dioxide (C0 2).

[0050] The oxidation electrode 27 is an electrode (anode) that oxidizes the substance

to be oxidized such as the substance or ions contained in the second electrolysis solution

25. For example, it oxidizes water (H 2 0) to produce oxygen or a hydrogen peroxide

solution or oxidizes chloride ions (Cl-) to produce chlorine. The oxidation electrode 27 is

disposed in the second storage part 26 to be immersed in the second electrolysis solution

25. The oxidation electrode 27 contains an oxidation catalyst for the substance to be

oxidized. As the oxidation catalyst, used is a material that decreases activation energy for

the oxidation of the substance to be oxidized, in other words, a material that lowers

reaction overpotential. 15

21586185_1 (GHMatters) P121160.AU

[0051] Examples of such an oxidation catalyst material include metals such as

ruthenium, iridium, platinum, cobalt, nickel, iron, and manganese. Further, binary metal

oxide, ternary metal oxide, quaternary metal oxide, or the like is usable. Examples of the

binary metal oxide include manganese oxide (Mn-O), iridium oxide (Ir-O), nickel oxide

(Ni-O), cobalt oxide (Co-O), iron oxide (Fe-O), tin oxide (Sn-O), indium oxide (In-O), and

ruthenium oxide (Ru-0). Examples of the ternary metal oxide include Ni-Fe-O, Ni-Co

0, La-Co-O, Ni-La-0, and Sr-Fe-O. Examples of the quaternary metal oxide include Pb

Ru-Ir-O and La-Sr-Co-O. The oxidation catalyst is not limited to these and may be metal

hydroxide containing cobalt, nickel, iron, manganese, or the like or a metal complex such

as a Ru complex or an Fe complex. A mixture of a plurality of materials may also be

used.

[0052] The oxidation electrode 27 may be formed of a composite material containing

both the oxidation catalyst and a conductive material. Examples of the conductive

material include carbon materials such as carbon black, activated carbon, fullerene, carbon

nanotube, graphene, ketjen black, and diamond, transparent conductive oxides such as

indium tin oxide (ITO), zinc oxide (ZnO), fluorine-doped tin oxide (FTO), aluminum

doped zinc oxide (AZO), and antimony-doped tin oxide (ATO), metals such as Cu, Al, Ti,

Ni, Ag, W, Co, and Au, and an alloy containing at least one of these metals. For example,

the oxidation electrode 27 may have a structure in which the oxidation catalyst in a thin

film form, a lattice form, a granular form, a wire form, or the like is provided on a

conductive base material. As the conductive base material, a metal material containing

titanium, a titanium alloy, or stainless steel is used, for instance.

[0053] The configurations and operations of the data processing unit 12 and so on in

the electrolysis device 1 illustrated in FIG. 1 will be described. The supply power control

unit 3 controls power for causing a redox reaction in the electrolysis cell 2A and is

electrically connected to the reduction electrode 23 and the oxidation electrode 27 of the

electrolysis cell 2A. A not-illustrated power source is connected to the supply power 16

21586185_1 (GHMatters) P121160.AU control unit 3. In the supply power control unit 3, electric devices such as a DC-AC converter, a DC-DC converter, an AC-DC converter, an inverter, a converter, and switches are installed. The power source connected to the supply power control unit 3 may be a power source that converts renewable energy to electric energy to supply it or may be a typical commercial power source, battery, or the like. Examples of the power source using the renewable energy include a power source that converts kinetic energy or potential energy such as wind power, water power, geothermal energy, or tidal power to electric energy, a power source such as a solar cell having a photoelectric conversion element that converts light energy to electric energy, a power source such as a fuel cell or a storage battery that converts chemical energy to electric energy, and a power source that converts vibrational energy such as sound to electric energy.

[0054] The supply power property obtaining unit 4 obtains the properties of the power,

that is, a voltage and a current, that is to be supplied to the electrolysis cell 2A. The

supply power properties obtained by the supply power property obtaining unit 4 are

transmitted to the data storage unit 11 through a signal line. The supply power control

unit 3 and the supply power property obtaining unit 4 may be independent structures or

may be an integrated structure.

[0055] The gas/electrolysis solution control unit 5 controls the flow rates of the C02

containing gas and the electrolysis solutions that are to be input to the electrolysis cell 2A.

It may further control the dew point, temperature, pressure, and so on of the gas and the

pressure, temperature, composition, pH, and so on of the electrolysis solutions. The input

gas property obtaining unit 6 obtains the flow rate and composition of the C02-containing

gas that is to be input to the electrolysis cell 2A. It may have a function of obtaining the

properties such as the dew point, temperature, pressure, and so on of the C02-containing

gas. The obtained input gas properties are transmitted to the data storage unit 11 through

a signal line. The gas/electrolysis solution control unit 5 and the input gas property

obtaining unit 6 may be independent structures or may be an integrated structure. 17

21586185_1 (GHMatters) P121160.AU

[0056] The electric property obtaining unit 7 obtains the electric properties such as cell

voltage and cell current of the electrolysis cell 2A. To improve the accuracy of equivalent

circuit parameters, it is preferable to assemble a reference electrode in the electrolysis cell

2A to obtain the potentials of the cathode 23 and the anode 27 relative to the reference

electrode. The electric property obtaining unit 7 may have a function of obtaining the

impedance of the electrolysis cell 2A. The electric properties are transmitted to the data

storage unit 11 through a signal line.

[0057] The output gas property obtaining unit 8 obtains the flow rate of the gas output

from the cathode 23 of the electrolysis cell 2A and the concentrations of C02 and various

gases produced through the C02 reduction reaction. It may further have a function of

obtaining the concentrations of H 2 and other gases produced through a side reaction. It

may also have a function of obtaining the flow rates of 02 and C02 which are output from

the anode 27, the concentrations of the gases, and so on. The output gas properties are

transmitted to the data storage unit 11 through a signal line.

[0058] The temperature control unit 9 controls the temperature of the electrolysis cell

2A to a predetermined value and has a function of controlling the heating by a heater

assembled in the electrolysis cell 2A and the flow of a refrigerant to a cooling water

channel. The temperature obtaining unit 10 obtains the temperature of the electrolysis

cell 2A. The obtained temperature is transmitted to the data storage unit 11 through a

signal line. The temperature control unit 9 and the temperature obtaining unit 10 may be

independent structures or may be an integrated structure.

[0059] The data storage unit 11 includes a control device such as a computer and has a

function of storing data in a recording medium such as a memory, a hard disk, or SSD and

a data transceiving function. The display unit 13 is a display and has a function of

displaying information sent from the data storage unit 11 and a deterioration detecting unit.

The data storage unit 11 and the display unit 13 may be independent structures or may be

an integrated structure such as a computer. 18

21586185_1 (GHMatters) P121160.AU

[0060] The data processing unit 12 includes a computer such as PC or a

microcomputer, for instance, and based on the data transmitted from the data storage unit

11, calculates an equivalent circuit model and equivalent circuit parameters. The data

processing unit 12 performs the inference of a deteriorated place, the calculation of a

deterioration degree, and so on using the equivalent circuit parameters. It further

determines whether to continue the operation of the C02 electrolysis cell 2A, whether to

execute its refresh operation, or whether to stop its operation, based on the information of

the deteriorated place and the deterioration degree, and transmits commands to the supply

power control unit 3, the gas/electrolysis solution control unit 5, and the temperature

control unit 9. The data processing unit 12 may be installed near the electrolysis cell 2A

or may be installed in the cloud to perform remote diagnosis. Installing the data

processing unit 12 in the cloud enables the integrated management of stored data of the

electrolysis cells 2A installed at various places to improve the accuracy of deterioration

detection. Because of this, the data processing unit 12 is preferably installed in the cloud.

[0061] Next, a deterioration detecting method of the electrolysis device 1 will be

described with reference to FIG. 3. First, database of an equivalent circuit model and

equivalent circuit parameters of the electrolysis cell 2A at design time is created and stored

in the data processing unit 12. Another method to create the database is to test-operate

the electrolysis cell 2A using the supply power control unit 3 and the gas/electrolysis

solution control unit 5, and calculate an equivalent circuit model before real operation,

obtain its circuit parameters, and create their database (Si). The real operation of the

electrolysis cell (or the electrolysis cell stack) 2 is started, the supply power properties, the

input gas properties, and the electric properties, output gas properties, and temperature of

the electrolysis cell 2A are obtained, and these data are stored in the data storage unit 11

(S2). These data are transmitted to the data processing unit 12, and the data processing

unit 12 performs an arithmetic operation to calculate an equivalent circuit model and

equivalent circuit parameters (S3). 19

21586185_1 (GHMatters) P121160.AU

[0062] The data processing unit 12 compares the equivalent circuit model and its

equivalent circuit parameters at the design time or before the real operation which are

obtained at Si with the equivalent circuit model and the equivalent circuit parameters

during the real operation to infer a deteriorated place and calculate a deterioration degree.

From the development of the deterioration degree, it further predicts a life span up to the

stop of the operation (S4). It is determined whether or not the deterioration degree

exceeds an operation stop standard (S5), and in the case where the deterioration degree

exceeds the operation stop standard, the real operation of the electrolysis cell (or the

electrolysis cell stack) 2 is stopped (S6). The maintenance appropriate for the

deteriorated place is performed or the electrolysis cell 2A is changed when the operation is

stopped (S7). The various property data stored in the data storage unit 11 at S2, the

equivalent circuit model and the equivalent circuit parameters which are calculated at S3,

and the deteriorated place, the deterioration degree, and the life span up to the operation

stop which are calculated at S4 are transmitted to the display unit 13, and are displayed on

the display unit 13 (S8).

[0063] Next, the operation of the electrolysis device 1 of C02 will be described. The

description here is about the case where using an aqueous solution containing C02 and an

aqueous potassium hydrogen carbonate (KHCO 3) solution as the electrolysis solutions 21,

25, mainly carbon monoxide (CO) is produced through the reduction of C02 and oxygen is

produced through the oxidation of water (H2 0) or hydroxide ions (OH-). The reduction

reaction of CO2 is not limited to the reaction of producing CO and may be a reaction of

producing CxHyO, specifically, a carbon compound such as formic acid (HCOOH),

methane (CH 4 ), methanol (CH 30H), ethane (C 2H 6 ), ethylene (C 2H 4 ), ethanol (C 2H 5 0H),

formaldehyde (HCHO), or ethylene glycol (C 2H 60 2 ).

[0064] When a voltage equal to or higher than an electrolysis voltage is applied across

the reduction electrode (cathode) 23 and the oxidation electrode (anode) 27, a reduction

reaction of C02 occurs near the reduction electrode 23 in contact with the first electrolysis 20

21586185_1 (GHMatters) P121160.AU solution 21. As shown by the following equation (1), electrons (e-) supplied from the power source reduce C02 contained in the first electrolysis solution 21 to produce CO and

OH-. As shown by the equation (2) and the equation (3), part of the produced OH- reacts

with C02, resulting in the production of hydrogen carbonate ions (HCO3-) or carbonate

ions (C0 32-). The voltage across the reduction electrode 23 and the oxidation electrode

27 causes part of OH-, HCO3-, and C03 2- to move into the second electrolysis solution 25

through the diaphragm 29.

2CO2 + 2H 2 0 + 4e- -- 2CO + 40H- ... (1)

2CO2 + 20H- -- 2HCO3- ... (2)

2HCO3- + 20H- -> C0 32- + H 2 0 ... (3)

[0065] Near the oxidation electrode 27 in contact with the second electrolysis solution

25, an oxidation reaction of water (H 20) occurs. As shown by the following equation (4),

the oxidation reaction of H2 0 contained in the second electrolysis solution 25 occurs,

electrons are lost, and oxygen (02) and hydrogen ions (H+) are produced.

2H20 -- 4H + 02 + 4e- ... (4)

As shown by the following equation (5) to equation (7), part of the produced

hydrogen ions (H+) reacts with part of hydroxide ions (OH-), hydrogen carbonate ions

(HCO3-), or carbonate ions (C0 32 -) which have moved through the diaphragm 29, resulting

in the production of H 20 and C02.

2H+ + C0 32 - -* H 2 0 + CO 2 (5)

2H+ + 2HCO3- --* 2H 20 + 2CO 2 (6)

H+ + OH- -> H 2 0 (7)

[0066] The above describes the operation based on the production of OH- in the

reduction electrode 23, but the operation may be based on the production and movement of

H+ in the oxidation electrode 27. When a voltage equal to or higher than the electrolysis

voltage is applied across the reduction electrode 23 and the oxidation electrode 27, an

oxidation reaction of water (H 2 0) occurs near the oxidation electrode 27 in contact with 21

21586185_1 (GHMatters) P121160.AU the second electrolysis solution 25. As shown by the following equation (8), the oxidation reaction of H 20 contained in the second electrolysis solution 25 occurs, electrons are lost, and oxygen (02) and hydrogen ions (H+) are produced. The produced hydrogen ions (H+) partly move into the first electrolysis solution 21 through the diaphragm 29.

2H20 -- 4H+ + 02 + 4e- (8)

[0067] When the hydrogen ions (H+) produced in the oxidation electrode 27 side reach

the vicinity of the reduction electrode 23 and electrons (e-) are supplied to the reduction

electrode 23 from the power source, a reduction reaction of carbon dioxide (C0 2) occurs.

As shown by the following equation (9), the hydrogen ions (H+) having moved to the

vicinity of the reduction electrode 23 and the electrons (e-) supplied from the power source

reduce C02 contained in the first electrolysis solution 21 to produce carbon monoxide

(CO).

2CO2 + 4H+ + 4e- -- 2CO + 2H 20 (9)

[0068] The data storage unit 11 illustrated in FIG. 1 is configured to store data from

the supply power property obtaining unit 4, the input gas property obtaining unit 6, the

electric property obtaining unit 7, the output gas property obtaining unit 8, and the

temperature obtaining unit 10. The data processing unit 12 is configured to receive the

aforesaid data from the data storage unit 11 and process the data to determine the state of

the electrolysis cell 2A. Specifically, the data processing unit 12 calculates the equivalent

circuit model and the equivalent circuit parameters of the electrolysis cell 2A based on the

processing results of the data and determines the state of the electrolysis cell 2A based on

the calculation results of the equivalent circuit model and the equivalent circuit parameters.

One specific example of the determination of the state of the electrolysis cell 2A is to infer

a deteriorated place or the like of the electrolysis cell 2A, and another specific example

thereof is to calculate a deterioration degree of the deteriorated place.

[0069] Next, a method of calculating the equivalent circuit model and the equivalent

circuit parameters, a method of inferring the deteriorated place, and a method of 22

21586185_1 (GHMatters) P121160.AU calculating the deterioration degree by the data processing unit 12 will be described with reference to FIG. 4. FIG. 4 illustrates an example of the equivalent circuit model of the

C02 electrolysis cell 2A. In the description here, the case where a C02 reduction product

(CxHyO) is produced through the reduction reaction of C02 will be taken as an example.

In the case where CO is produced, CxHyOz can be replaced by CO. In a cathode part 24

in the equivalent circuit model, a CxHyOz producing part and a side reaction H 2 producing

part are connected in parallel, and cathode resistance is connected in series to them. A

diaphragm part 29 has diaphragm resistance. In an anode part 28, an 02 producing part

and anode resistance are connected in series. The cathode part 24, the diaphragm part 29,

and the anode part 29 are connected in series.

[0070] The current densities JA of the CxHyOz producing part, the H2 producing part,

and the 02 producing part are represented by the Tafel equation in the following formula

(10), for instance.

[Math. 1]

In the subscript A, CxHyOz ER (CxHyOzEvolution Reaction) is entered in the case

of CxHyOzproduction, HER (Hydrogen Evolution Reaction) is entered in the case of H2

production, and OER (Oxygen Evolution Reaction) is entered in the case of 02 production.

Jo, A represents exchange current density, BA represents Tafel slope, and lA represents

overvoltage. Note that Jo,A and BA are parameters that vary with temperature T. The

cathode resistance is represented by Rathode, the diaphragm resistance is represented by

Rmembrane, the anode resistance is represented by Ranode. These are parameters that vary

with temperature.

[0071] In the case where the flow rate of C02 introduced to the C02 electrolysis cell

2A is high enough, the formula (10) is usable. In the case where the C02 flow rate is low

and consideration is given to that the CxHyOz production current density is restricted by the

C02 flow rate, that is, has a limit, the current sity JCxHyOz ER include low C02of the CxHyOz 23

21586185_1 (GHMatters) P121160.AU producing part is represented by a relational formula including, as variables, the Tafel equation in the formula (10) and theCxHyO production limit current density JCxHyOz ER, L as shown by the following formula (11). Here, fIindicates a function.

[Math. 2]

[0072] As shown by the equation (2), the equation (3), the equation (5), and the

equation (6), C02 in the cathode side is converted to HCO3- and C03 2 - and they move to

the anode side and are converted again to C02. Here, the flow rate of C02 moving from

the cathode side to the anode side as a result of the aforesaid ion movement is represented

by flowCO2 from cathode to anode. Since the flow rate ofCO2 usable for the production of

CxHyOz decreases by an amount corresponding to the flow rate of C02 moving from the

cathode side to the anode side, the CxHyOz production limit current density JCxHyOz ER, L is

represented by a relational formula including, as variables, the flow rate flowCO2 cathode, input

of C02 introduced to the cathode part and the flow rate nowCO2 from cathode to anode of C02

moving from the cathode side to the anode side, as shown by the following formula (12).

Here, f2 indicates a function.

[Math. 3]

[0073] The current Icell flowing in the electrolysis cell illustrated in FIG. 4 has the

following relation with the current JCxHyOz ER include low C02 (this may be JCxHyOz ER) used for

the production of CxHyOz and the current JHER used for the production of H 2 .

[Math. 4]

"Aelectrode" is an electrode area of the cathode or the anode, and tyically, the

cathode and the anode have the same electrode area in many cases. Further, the cell

voltage Vcei is represented as follows.

[Math. 5] 24

21586185_1 (GHMatters) P121160.AU

E0OER and ECxHyOz are theoretical potentials of 02 production and CxHyOz

production and vary with temperature. Rcathode is the cathode resistance, Rmembrane is the

diaphragm resistance, and Ranode is the anode resistance.

[0074] Next, FIG. 5 illustrates the equivalent circuit parameters of the equivalent

circuit model illustrated in FIG. 4. Using one of or two or more of the supply power

properties, the input gas properties, and the electric properties, output gas properties, and

temperature of the C02 electrolysis cell which are collected before the real operation, the

equivalent circuit parameters of these are calculated by fitting. For the fitting,

spreadsheet software or a circuit simulator is usable. Using the data sent from the data

storage unit 11 to the data processing unit 12 during the real operation, the equivalent

circuit parameters are periodically calculated, and the equivalent circuit parameters before

the real operation or at the design time and the equivalent circuit parameters during the real

operation are compared, whereby it is possible to infer a deteriorated place.

[0075] Further, for each of the equivalent circuit parameters, the deterioration degree

D can be calculated based on the following formula (15).

[Math. 6]

Setting a determination standard for the aforesaid deterioration degree D enables

the determination on operation stop, refresh operation, or maintenance. Further, the

development over time of the deterioration degree D can be represented by a regression

formula which is a linear function shown in the following formula (16), for instance.

[Math. 7]

In the math expression, "a" is a variation of D per unit time and "b" is an intercept.

The use of the formula (16) enables the estimation of the remaining time up to the

determination standard. An approximate formula of the development over time of the

deterioration degree D is not limited to the formula (16) and may be a quadratic formula or 25

21586185_1 (GHMatters) P121160.AU a polynomial. Further, the remaining time up to the determination standard may be estimated using machine learning based on database of other electrolysis cell's equivalent circuit parameters and deterioration degrees stored in the data processing unit 12.

[0076] (Second Arrangement)

Next, the configuration and a deterioration detecting system of a carbon dioxide

electrolysis device of a second arrangement will be described with reference to FIG. 1 and

FIG. 6. The deterioration detecting system of the carbon dioxide electrolysis device 1 of

the second arrangement is the same as the deterioration detecting system of the first

arrangement. In the carbon dioxide electrolysis device 1 of the second arrangement, a

contact form of a gas containing C02 (sometimes referred to as a C02 gas) with a reduction

electrode 23 and a contact form of a second electrolysis solution (anolyte) containing water

with an oxidation electrode 27 in an electrolysis cell 2B are different from those in the

electrolysis cell 2A of the first arrangement. The electrolysis cell 2B of the carbon

dioxide electrolysis device 1 of the second arrangement differs in the configuration from

the electrolysis cell 2A according to the first arrangement. Except for the above, the

configurations of its parts, for example, the specific configurations of the reduction

electrode 23, the oxidation electrode 27, a diaphragm 29, the second electrolysis solution,

and so on are the same as those of the first arrangement.

[0077] The electrolysis cell 2B according to the second arrangement includes the

reduction electrode 23, the oxidation electrode 27, the diaphragm 29, a first channel 36 in

which the gas containing C02 flows, a second channel 37 in which the second electrolysis

solution (anolyte) containing water flows, a first current collector plate 38 electrically

connected to the reduction electrode 23, and a second current collector plate 39 electrically

connected to the oxidation electrode 27. The reduction electrode 23 and the first channel

36 facing it form a cathode part (reduction electrode chamber) 24. The oxidation

electrode 27 and the second channel 37 facing it form an anode part (oxidation electrode

chamber) 28. 26

21586185_1 (GHMatters) P121160.AU

[0078] In the second arrangement, a first electrolysis solution containing C02 instead

of the gas containing C02 may flow in the first channel 36. Another adoptable

configuration is to provide a not-illustrated channel between the reduction electrode 23 and

the diaphragm 29, have the gas containing C02 flow in the first channel 36, and have the

first electrolysis solution flow in the channel between the reduction electrode 23 and the

diaphragm 29. The first electrolysis solution used in this case may contain C02 or may

be one not containing CO2. Further, instead of the second electrolysis solution containing

water, a gas containing water vapor is also usable.

[0079] During the operation of the electrolysis cell 2B, the supply of the gas

containing C02 is sometimes stopped because the first channel 36 is clogged when a

reduction product of C02 or a component of the second electrolysis solution having moved

to the reduction electrode 23 side solidifies to precipitate in the first channel 36.

Therefore, in order to inhibit the formation of the precipitates, the gas containing C02

preferably contains moisture. However, too large a moisture content in the gas containing

C02 is not preferable because this results in the supply of a large amount of moisture to the

surface of a catalyst in the reduction electrode 23 to easily cause the production of

hydrogen. Therefore, the moisture content in the gas containing C02 is preferably 20% to

90% and more preferably 30% to 70% in terms of relative humidity.

[0080] A first supply channel 31 that supplies the gas containing C02 and a first

discharge channel 33 that discharges a produced gas are connected to the first channel 36.

A second supply channel 34 that supplies the electrolysis solution containing water and a

second discharge channel 35 are connected to the second channel 37. The first channel

36 is disposed to face the reduction electrode 23. The first channel 36 is connected to the

first supply channel 31 and is supplied with the gas containing C02 from the first supply

channel31. The C02 gas or the first electrolysis solution (catholyte) comes into contact

with the reduction electrode 23 when it flows in the first channel 36. C02 in the C02 gas

or the catholyte passing through the reduction electrode 23 is reduced by the reduction 27

21586185_1 (GHMatters) P121160.AU electrode 23. A gas or solution containing a reduction reaction product of C02 is discharged from the first discharge channel 33.

[0081] The second channel 37 is disposed to face the oxidation electrode 27. A not

illustrated solution tank or the like is connected to the second channel 37, and the anolyte

comes into contact with the oxidation electrode 27 when it flows in the second channel 37.

H 20 in the anolyte passing through the oxidation electrode 27 is oxidized by the oxidation

electrode 27.

[0082] In the deterioration detecting system of the carbon dioxide electrolysis device

of the second arrangement, the equivalent circuit model illustrated in FIG. 4 can be

employed as in the first arrangement, and the equivalent circuit parameters illustrated in

FIG. 5 are calculated by fitting. Using data sent from the data storage unit 11 to the data

processing unit 12 during operation, the equivalent circuit parameters are periodically

calculated, and equivalent circuit parameters before the real operation or at design time are

compared with the equivalent circuit parameters during the real operation, whereby a

deteriorated place can be inferred. Further, by setting a determination standard for a

deterioration degree D, it is possible to determine whether to stop the operation, whether to

execute a refresh operation, and whether to perform maintenance.

[0083] (Third Arrangement)

The configuration and a deterioration detecting system of a carbon dioxide

electrolysis device of a third arrangement will be described with reference to FIG. 1, FIG.

6, and FIG. 7. The carbon dioxide electrolysis device of the third arrangement includes

two H 2 production equivalent circuits. The electrolysis device of the third arrangement

has the same configuration and deterioration detecting system as those of the electrolysis

device of the first arrangement or the second arrangement. An electrolysis cell according

to the third arrangement has the same configuration as that of the electrolysis cell

according to the second arrangement, for instance. However, an equivalent circuit model

used in the data processing unit according to the third arrangement is different from the 28

21586185_1 (GHMatters) P121160.AU equivalent circuit model according to the first arrangement. The equivalent circuit model used in the data processing unit 12 according to the third arrangement will be described with reference to FIG. 7.

[0084] FIG. 7 illustrates an example of the equivalent circuit model of the carbon

dioxide electrolysis cell. In the description here, the case where CxHyOz is produced

through a C02 reduction reaction is taken as an example. In the case of CO production,

CxHyOzcan be replaced by CO. In a cathode part of the equivalent circuit model, a

CxHyO producing part and two side reaction H2 producing parts are connected in parallel,

and cathode resistance is connected thereto in series. The H 2 producing parts are a H2

producing part employed for a low current density region (low current density) and a H2

producing part employed for a high current density region (high current density), and they

are connected in parallel. A diaphragm part is diaphragm resistance. In an anode part,

an 02 producing part and anode resistance are connected in series. The cathode part, the

diaphragm part, and the anode part are connected in series.

[0085] In the parameter of the Tafel equation in the formula (10), in the case where the

subscript A is the H 2 producing part (low current density), "HER low" is used, and in the

case where it is the H 2 producing part (high current density), "HER high" is used. FIG. 8

illustrates equivalent circuit parameters of the equivalent circuit model according to the

third arrangement. Using the supply power properties, the input gas properties, and the

electric properties, output gas properties, and temperature of the electrolysis cell which are

collected before real operation, these equivalent circuit parameters are calculated by fitting.

For the fitting, spreadsheet software or a circuit simulator is usable. Using data sent from

the data storage unit 11 to the data processing unit 12 during the real operation, the

equivalent circuit parameters are periodically calculated, and the equivalent circuit

parameters before the real operation or at design time are compared with the equivalent

circuit parameters during the real operation, whereby a deteriorated place can be inferred.

Further, by setting a determination standard for a deterioration degree D, it is possible to 29

21586185_1 (GHMatters) P121160.AU determine whether to stop the operation, whether to execute a refresh operation, or whether to perform maintenance.

[0086] (Fourth Arrangement)

The configuration and a deterioration detecting system of an electrolysis device of

a fourth arrangement will be described with reference to FIG. 1, FIG. 2, FIG. 6, and FIG.

9. The electrolysis device of the fourth arrangement is a device that electrolyzes and

reduces nitrogen (N 2 ) to produce ammonia (NH 3 ). The electrolysis device of the fourth

arrangement is the same in the device configuration itself as the electrolysis device 1 of the

first arrangement illustrated in FIG. 1 though being different in an electrolyte and an

electrolysis product. Further, in the electrolysis device of the fourth arrangement, an

electrolysis cell is also the same as the electrolysis cell 2A illustrated in FIG. 2. In the

electrolysis device of the fourth arrangement, an electrolysis cell having the same

configuration as that of the electrolysis cell 2B illustrated in FIG. 6 may also be used.

[0087] In the fourth arrangement, a substance to be reduced in the cathode part of the

electrolysis cell illustrated in FIG. 2, which is nitrogen (N 2), and an equivalent circuit

model are different from those in the first arrangement. The first electrolysis solution

stored in the cathode part contains N 2 as the substance to be electrolyzed. Alternatively,

in the electrolysis cell illustrated in FIG. 6, a N 2 gas may be supplied as the substance to be

electrolyzed to the cathode part.

[0088] In the case where nitrogen (N 2 ) is reduced, the first electrolysis solution

preferably contains an ammonia production catalyst and a reducing agent for the

production of ammonia through the N 2 reduction, separately from an electrochemical

reaction. As the reducing agent, a halide (II) or the like of a lanthanoid metal is used.

Examples of the lanthanoid metal include lanthanum (La), cerium (Ce), praseodymium

(Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium

(Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium

(Yb), and lutetium (Lu), among which Sm is preferable. Examples of halogen include 30

21586185_1 (GHMatters) P121160.AU chlorine (Cl), bromide (Br), and iodine (I), among which iodine is preferable. As the halide (II) of the lanthanoid metal, samarium(II) iodide (SmI2) is more preferable.

[0089] The ammonia production catalyst promotes the production of ammonia from

nitrogen under the presence of the reducing agent, and is, but not limited to, a molybdenum

complex, for instance. Examples of the ammonia production catalyst include

molybdenum complexes (A) to (D) listed below, for instance.

[0090] A first example is (A) a molybdenum complex having, as a PCP ligand, N,N

bis(dialkyl-phosphinomethyl)dihydrobenzo imidazolidine (where the two alkyl groups may

be identical or may be different, and at least one hydrogen atom of the benzene ring may

be replaced by an alkyl group, an alkoxy group, or a halogen atom).

[0091] A second example is (B) a molybdenum complex having, as a PNP ligand, 2-6

bis(dialkyl-phosphinomethyl)pyridine (where the two alkyl groups may be identical or may

be different, and at least one hydrogen atom of the pyridine ring may be replaced by an

alkyl group, an alkoxy group, or a halogen atom).

[0092] A third example is (C) a molybdenum complex having, as a PPP ligand,

bis(dialkyl-phosphinomethyl)arylphosphine (where the two alkyl groups may be identical

or may be different).

[0093] A fourth example is (D) a molybdenum complex represented by trans

Mo(N 2 )2 (R1R2R3P) 4 (where R, R2, and R3 are alkyl groups or aryl groups that may be

identical or may be different, and two R3's may be linked to form an alkylene chain).

[0094] In the above molybdenum complexes, the alkyl group may be, for example, a

methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group,

or a straight-chain or branched alkyl group such as a structural isomer of any of these, or

may be a cyclic alkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl

group, or a cyclohexyl group. The carbon number of the alkyl group is preferably 1 to 12,

and more preferably 1 to 6. The alkoxy group may be, for example, a methoxy group, an

ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a hexyloxy group, or a 31

21586185_1 (GHMatters) P121160.AU straight-chain or branched alkoxy group such as a structural isomer of any of these, or may be a cyclic alkoxy group such as a cyclopropoxy group, a cyclobutoxy group, a cyclopentoxy group, or a cyclohexyloxy group. The carbon number of the alkoxy group is preferably 1 to 12, and more preferably 1 to 6. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0095] The amount of the ammonia production catalyst used may be appropriately

selected within a range of 0.00001 to 0.1 mol/L equivalent weight, and is preferably 0.0001

to 0.05 mol/L equivalent weight, and more preferably 0.0005 to 0.01 mol/L equivalent

weight, relative to the electrolysis solution.

[0096] Next, the operation of the electrolysis device to produce ammonia through the

N 2 reduction reaction will be described. When a voltage equal to or higher than an

electrolysis voltage is applied across the reduction electrode (cathode) and the oxidation

electrode (anode), an oxidation reaction of water (H 2 0) or hydroxide ions (OH-) in the

second electrolysis solution occurs electrochemically in the oxidation electrode. For

example, in the case where the second electrolysis solution has a hydrogen ion

concentration of 7 or less (pH 7), H2 0 is oxidized and 02 and H+ are produced based on

the following equation (17). In the case where the hydrogen ion concentration of the

second electrolysis solution is larger than 7 (pH > 7), OH- is oxidized and 02 and H 20 are

produced based on the following equation (18).

3H 20-- 3/202+ 6H++ 6e- ... (17)

60H-- 3/202 + 3H 20 + 3H 20 + 6e- ... (18)

[0097] In the first storage part (first electrolysis tank) 22, separately from the

electrochemical reaction, nitrogen (N 2 ) in the first electrolysis solution is reduced by the

ammonia production catalyst and the reducing agent, resulting in the production of

ammonia (NH 3). In the case where, for example, SmI2 is used as the reducing agent, N 2

in the first electrolysis solution is reduced, resulting in the production of ammonia (NH 3 )

based on the following equation (19). 32

21586185_1 (GHMatters) P121160.AU

N 2 + 6SmI2 + 6H20 -- 2NH 3 + 6SmI2 (OH) ... (19)

[0098] As shown by the above equation (19), as a result of the production of NH 3 , the

reducing agent SmI2 is oxidized, and if this state is left as it is, SmI2 loses the function as

the reducing agent. That is, in the case where the reduction reaction of N 2 in the first

electrolysis solution is caused in a first electrolysis tank not having a reduction electrode

that electrochemically causes the reduction reaction, the reduction reaction of N 2 stops and

the production of NH3 finishes at an instant when the reducing agent in the amount put into

the first electrolysis tank in the initial state is consumed by the reduction reaction of N 2

. Regarding this point, in the electrolysis device of the arrangement, since the reduction

electrode that causes the electrochemical reduction reaction is disposed in the first

electrolysis tank, the reducing agent resulting from the oxidation by the reduction

electrode, that is, SmI2(OH), can be reduced to be regenerated based on the following

equation (20). This enables the reduction reaction of N 2 to continuously last. The

amount of the reducing agent used is preferably 0.01 to 2 mol/L, more preferably 0.1 to 1

mol/L relative to the first electrolysis solution in order to promote its reaction with the

ammonia production catalyst.

6SmI2(OH) + 6e- -- 6SmI2 + 60H- (20)

[0099] FIG. 9 illustrates an equivalent circuit model of the electrolysis cell that

produces NH 3 using SmI2 as the reducing agent. As shown by the aforesaid equation

(20), SmI2(OH) is electrochemically regenerated into SmI2. For this purpose, in a cathode

part of the equivalent circuit model, a SmI2 regenerating part and a side reaction H2

producing part are connected in parallel. The current density of the SmI2 regenerating

part is represented by the Tafel equation in the aforesaid formula (10). In the subscript A

in the formula (10), SmI2 RR (SmI2 regeneration reaction) is entered.

[0100] (Fifth Arrangement)

A method of designing an electrolysis device and an electrolysis system of a fifth

arrangement will be described with reference to FIG. 10. The electrolysis system of the 33

21586185_1 (GHMatters) P121160.AU fifth arrangement is the same as the electrolysis system of the first and second arrangement. In the method of designing the electrolysis system of the fifth arrangement, the system is designed using the equivalent circuit model and the equivalent circuit parameters of any of the first to fourth arrangements.

[01011 First, an electrolysis cell serving as a reference (reference electrolysis cell) is

operated, the supply power properties, the input gas properties, the electric properties, the

output gas properties, and the temperature properties are obtained, and their measurement

data are stored in the data storage unit (Si). Before the measurement data are obtained, it

is preferable to execute an aging operation of passing a current in advance to stabilize cell

properties. Since the cell properties are more stabilized as the time of the aging operation

is longer, the time of the aging operation is preferably one hour or longer, and more

preferably two hours or longer. The data processing unit selects a candidate for the

equivalent circuit model of the electrolysis cell (S2).

[0102] The data processing unit calculates parameters of the equivalent circuit model

by fitting such that a square error between the measurement data of the reference

electrolysis cell obtained at Si and simulation data of the equivalent circuit model becomes

small (S3). A determination standard for the square error between the measurement data

and the simulation data of the equivalent circuit model is set in advance, and when the

square error is larger than the determination standard, the candidate for the equivalent

circuit model at S2 is changed. In the case where the square error is smaller than the

determination standard, it is determined that the equivalent circuit model selected at S2 is

valid (S4). The electrolysis system is designed using the equivalent circuit model

determined as valid and the parameters of the equivalent circuit model (S5).

EXAMPLE

[0103] Next, an example and its evaluation results will be described.

[0104] (Example 1) 34

21586185_1 (GHMatters) P121160.AU

The carbon dioxide electrolysis cell whose configuration is illustrated in FIG. 6

was manufactured. The carbon dioxide electrolysis cell was operated by the deterioration

detecting system of the electrolysis device illustrated in FIG. 1. As the reduction

electrode in the carbon dioxide electrolysis cell, an electrode in which gold nanoparticle

carrying carbon particles were applied on carbon paper was used. The average particle

size of the gold nanoparticles was 2 nm, and their carried amount was 10% by mass. As

the oxidation electrode, an electrode in which IrO2 nanoparticles were applied on a Ti mesh

was used. As the diaphragm, an anion exchange membrane was used. The reduction

electrode and the oxidation electrode cut to have a 16 cm2 electrode area were used. As

in the carbon dioxide electrolysis cell whose structure is illustrated in FIG. 6, the first

current collector plate, the first channel, the reduction electrode, the diaphragm, the

oxidation electrode, the second channel, and the second current collector plate were

stacked in order from the left, and the resultant was sandwiched by an insulating plate, a

cooling water channel, and a support plate, which are not illustrated, to form the carbon

dioxide electrolysis cell. Further, to simply monitor a reduction electrode potential and an

oxidation electrode potential, a not-illustrated Pt foil as a reference electrode was brought

into contact with a reduction electrode side of the diaphragm.

[0105] Using the gas/electrolysis solution control unit, CO 2 was introduced to the first

channel of the carbon dioxide electrolysis cell at a flow rate of 80 secm, and a 0.1 M

KHCO3 electrolysis solution was introduced to the second channel at a flow rate of 10

mL/min. Further, using the temperature control unit and the temperature obtaining unit,

the carbon dioxide electrolysis cell was temperature-controlled to 40°C while a heater and

a cooling water channel, which are not illustrated, were in close contact with the carbon

dioxide electrolysis cell. As the supply power control unit, the supply power property

obtaining unit, and the electric property obtaining unit, used was a potentiostat/galvanostat

in which their functions are integrated. As the output gas property obtaining unit, a

volumetricflow meter or a gas chromatograph was used. 35

21586185_1 (GHMatters) P121160.AU

[0106] A current was passed to the carbon dioxide electrolysis cell, and current density

dependences of the supply power properties (supplied current and voltage), the input gas

properties (the flow rate of a gas input to the cathode), the cell temperature, the electric

properties (cell current, cell voltage, cathode potential, anode potential, cell resistance),

and the output gas properties (the flow rates of gases output from the cathode and the

anode, the concentrations of various gases) were obtained. In the cathode, Co was

produced through a C02 reduction reaction and H 2 was produced through a side reaction.

In the anode, 02 was produced through an oxidation reaction of water. Since the behavior

of a H2 production reaction in a low current density region and that in a high current

density region were different, the circuit illustrated in FIG. 7 in which the CO producing

part and the two H2 producing parts are connected in parallel was used as the equivalent

circuit model.

[0107] A CO part current density (current density contributing to CO production) and

a H 2 part current density (current density contributing to H 2 production) were calculated

from the flow rate of the gas output from the cathode and the gas concentrations of CO and

H 2, and equivalent circuit parameters were decided such that errors between measurement

data and simulation data of the CO part current density Jco, the H 2 part current density JH2,

the cell voltage Vei, the cathode potential Vc, and the anode potential Va became small

as illustrated in FIG. 11 and FIG. 12. As illustrated in FIG. 13, FIG. 14, and FIG. 15, the

simulation data of CO Faraday efficiency (FEco), H 2 Faraday efficiency (FEH2), cathode

output gases (CO, H 2 , and CO2), and anode output gases (02 and CO2) well reproduce the

measurement data. Therefore, using the equivalent circuit model in FIG. 7 to study

changes in the equivalent circuit parameters during operation enables the detection of

deterioration.

[0108] It should be noted that the configurations of the above-described arrangements

may be employed in combination, and they may be partly replaced. While certain

arrangements of the present invention have been described here, these arrangements have 36

21586185_1 (GHMatters) P121160.AU been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel arrangements described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the arrangements described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.

[0109] (Numbered Clauses relating to the arrangements) 1. An electrolysis device comprising:

an electrolysis cell including a cathode part to be supplied with a gas or a liquid

containing a substance to be reduced and in which a reduction electrode is disposed, an

anode part to be supplied with a liquid containing a substance to be oxidized and in which

an oxidation electrode is disposed, and a diaphragm provided between the cathode part and

the anode part;

a supply power property obtaining unit that obtains a property of power that is to

be supplied to the electrolysis cell;

an input gas property obtaining unit that obtains a property of a gas that is to be

input to the electrolysis cell;

an electric property obtaining unit that obtains an electric property of the

electrolysis cell;

an output gas property obtaining unit that obtains a property of an output gas of

the electrolysis cell;

a temperature control unit that controls a temperature of the electrolysis cell;

a temperature obtaining unit that obtains the temperature of the electrolysis cell;

a data storage unit that stores data from the supply power property obtaining unit,

the input gas property obtaining unit, the electric property obtaining unit, the output gas

property obtaining unit, and the temperature obtaining unit; and

a data processing unit to which the data is sent from the data storage unit and that

37

21586185_1 (GHMatters) P121160.AU processes the data to determine a state of the electrolysis cell.

2. The electrolysis device according to clause 1,

wherein the data processing unit is configured to calculate an equivalent circuit

parameter by fitting using measurement data from at least one of the supply power

property obtaining unit, the input gas property obtaining unit, the electric property

obtaining unit, the output gas property obtaining unit, and the temperature obtaining unit

and simulation data of an equivalent circuit model of the electrolysis cell, and to detect

deterioration based on information of the equivalent circuit parameter.

3. The electrolysis device according to clause 2,

wherein the data processing unit is configured to infer a deteriorated place by

comparing the equivalent circuit parameter before real operation or at design time with the

equivalent circuit parameter during the real operation.

4. The electrolysis device according to clause 3,

wherein the data processing unit is configured to find a deterioration degree of the

equivalent circuit parameter, and to determine whether to stop the operation of the

electrolysis cell by setting a determination standard for the deterioration degree, the

deterioration degree being represented by [(the equivalent circuit parameter during the real

operation) - (the equivalent circuit parameter before the real operation or at the design

time)] / (the equivalent circuit parameter before the real operation or at the design time).

5. The electrolysis device according to any one of clause 2 to clause 4,

wherein the data processing unit is configured to calculate an equivalent circuit as

the equivalent circuit model, the equivalent circuit including: a cathode part having a

carbon dioxide reduction substance producing part and a hydrogen producing part that are

connected in parallel and to which a series resistance is connected in series; a diaphragm

part; and an anode part having an oxygen producing part and a series resistance that are

connected in series, the cathode part, the diaphragm part, and the anode part being

connected in series. 38

21586185_1 (GHMatters) P121160.AU

6. The electrolysis device according to clause 5,

wherein the data processing unit is configured to calculate a current density of the

carbon dioxide reduction substance producing part of the equivalent circuit model based on

a relational formula including, as variables, a current density represented by a Tafel

equation and a production limit current density of the carbon dioxide reduction substance.

7. The electrolysis device according to a clause 6,

wherein the data processing unit is configured to calculate the production limit

current density of the carbon dioxide reduction substance based on a relational formula

including, as variables, a flow rate of the substance to be reduced introduced to the cathode

part and a flow rate of the substance to be reduced that has moved to the anode part from

the cathode part.

8. The electrolysis device according to any one of clause 1 to clause 7,

wherein the data processing unit is installed in a cloud and is configured to

determine the state of the electrolysis cell remotely.

9. The electrolysis device according to any one of clause 1 to clause 8,

wherein the electrolysis cell is configured to produce a carbon compound by

supplying carbon dioxide as the substance to be reduced, or to produce ammonia by

supplying nitrogen as the substance to be reduced.

10. An electrolysis method comprising:

supplying a gas or a liquid containing a substance to be reduced to a cathode part

of an electrolysis cell, supplying a liquid containing a substance to be oxidized to an anode

part of the electrolysis cell, and operating the electrolysis cell, the electrolysis cell

including the cathode part in which a reduction electrode is disposed, the anode part in

which an oxidation electrode is disposed, and a diaphragm provided between the cathode

part and the anode part;

obtaining property data of power that is to be supplied to the electrolysis cell,

property data of a gas that is to be input to the electrolysis cell, electric property data of the 39

21586185_1 (GHMatters) P121160.AU electrolysis cell, property data of an output gas of the electrolysis cell, and temperature data of the electrolysis cell, all the data being obtained during the operation of the electrolysis cell; and processing the property data of the power, the property data of the gas, the electric property data, the property data of the output gas, and the temperature data to obtain an equivalent circuit model and an equivalent circuit parameter of the electrolysis cell, and determining a state of the electrolysis cell, using the equivalent circuit model and the equivalent circuit parameter of the electrolysis cell.

11. The electrolysis method according to clause 10,

wherein the determining the state of the electrolysis cell comprises determining a

deterioration state of the electrolysis cell, using the equivalent circuit model and the

equivalent circuit parameter.

12. The electrolysis method according to clause 11,

wherein the determining the state of the electrolysis cell comprises calculating the

equivalent circuit parameter by fitting, using the obtained data and simulation data of the

equivalent circuit model, and detecting a deterioration of the electrolysis cell

based on information of the equivalent circuit parameter.

13. The electrolysis method according to clause 11 or clause 12,

wherein the determining the state of the electrolysis cell comprises finding a

deterioration degree of the equivalent circuit parameter, and determining whether to stop

the operation of the electrolysis cell by setting a determination standard for the

deterioration degree, the deterioration degree being represented by [(the equivalent circuit

parameter during the real operation) - (the equivalent circuit parameter before the real

operation or at the design time)]/(the equivalent circuit parameter before the real operation

or at the design time).

14. The electrolysis method according to clause 10,

wherein the obtaining the data of the electrolysis cell comprises obtaining data of 40

21586185_1 (GHMatters) P121160.AU a reference electrolysis cell, and wherein the electrolysis cell is designed based on the equivalent circuit model and the equivalent circuit parameter that are derived from the data of the reference electrolysis cell.

15. The electrolysis method according to clause 14, further comprising:

selecting a candidate for the equivalent circuit model;

calculating the equivalent circuit parameter by fitting such that a square error

between the data of the reference electrolysis cell and simulation data of the selected

equivalent circuit model becomes small; and

determining whether the equivalent circuit parameter is valid, using the square

error between the data of the reference electrolysis cell and the simulation data of the

equivalent circuit parameter; and

designing the electrolysis cell using the equivalent circuit model and the

equivalent circuit parameter determined as valid.

[0110] In the claims which follow and in the preceding description of the invention,

except where the context requires otherwise due to express language or necessary

implication, the word "comprise" or variations such as "comprises" or "comprising" is

used in an inclusive sense, i.e. to specify the presence of the stated features but not to

preclude the presence or addition of further features in various embodiments of the

invention.

[0111] It is to be understood that, if any prior art publication is referred to herein, such

reference does not constitute an admission that the publication forms a part of the common

general knowledge in the art, in Australia or any other country.

41

21586185_1 (GHMatters) P121160.AU

Claims (15)

1. An electrolysis device comprising:

an electrolysis cell including a cathode part to be supplied with a gas or a liquid

containing a substance to be reduced and in which a reduction electrode is disposed, an

anode part to be supplied with a liquid containing a substance to be oxidized and in which

an oxidation electrode is disposed, and a diaphragm provided between the cathode part and

the anode part;

a supply power property obtaining unit that obtains a property of power that is to

be supplied to the electrolysis cell;

an input gas property obtaining unit that obtains a property of a gas that is to be

input to the electrolysis cell;

an electric property obtaining unit that obtains an electric property of the

electrolysis cell;

an output gas property obtaining unit that obtains a property of an output gas of

the electrolysis cell;

a temperature control unit that controls a temperature of the electrolysis cell;

a temperature obtaining unit that obtains the temperature of the electrolysis cell;

a data storage unit that stores data from the supply power property obtaining unit,

the input gas property obtaining unit, the electric property obtaining unit, the output gas

property obtaining unit, and the temperature obtaining unit;

a data processing unit to which the data is sent from the data storage unit and that

processes the data to obtain an equivalent circuit model and an equivalent circuit parameter

of the electrolysis cell and determine a state of the electrolysis cell using the equivalent

circuit model and the equivalent circuit parameter of the electrolysis cell; and

a display unit that displays information including the equivalent circuit model, the

equivalent circuit parameter, and the determined state. 42

21586185_1 (GHMatters) P121160.AU

2. The electrolysis device according to claim 1,

wherein the data processing unit is configured to calculate the equivalent circuit

parameter by fitting using measurement data from at least one of the supply power

property obtaining unit, the input gas property obtaining unit, the electric property

obtaining unit, the output gas property obtaining unit, and the temperature obtaining unit

and simulation data of the equivalent circuit model of the electrolysis cell, and to detect

deterioration based on information of the equivalent circuit parameter.

3. The electrolysis device according to claim 2,

wherein the data processing unit is configured to infer a deteriorated place and

calculate a deterioration degree by comparing the equivalent circuit parameter before real

operation or at design time with the equivalent circuit parameter during the real operation.

4. The electrolysis device according to claim 3,

wherein the data processing unit is configured to find a deterioration degree of the

equivalent circuit parameter, and to determine whether to stop the operation of the

electrolysis cell by setting a determination standard for the deterioration degree, the

deterioration degree being represented by [(the equivalent circuit parameter during the real

operation) - (the equivalent circuit parameter before the real operation or at the design

time)] / (the equivalent circuit parameter before the real operation or at the design time).

5. The electrolysis device according to any one of claim 2 to claim 4,

wherein the data processing unit is configured to calculate an equivalent circuit as

the equivalent circuit model, the equivalent circuit including: a cathode part having a

carbon dioxide reduction substance producing part and a hydrogen producing part that are

connected in parallel and to which a series resistance is connected in series; a diaphragm

part; and an anode part having an oxygen producing part and a series resistance that are 43

21586185_1 (GHMatters) P121160.AU connected in series, the cathode part, the diaphragm part, and the anode part being connected in series.

6. The electrolysis device according to claim 5,

wherein the data processing unit is configured to calculate a current density of the

carbon dioxide reduction substance producing part of the equivalent circuit model based on

a relational formula including, as variables, a current density represented by a Tafel

equation and a production limit current density of the carbon dioxide reduction substance.

7. The electrolysis device according to claim 6,

wherein the data processing unit is configured to calculate the production limit

current density of the carbon dioxide reduction substance based on a relational formula

including, as variables, a flow rate of the substance to be reduced introduced to the cathode

part and a flow rate of the substance to be reduced that has moved to the anode part from

the cathode part.

8. The electrolysis device according to any one of claim 1 to claim 7,

wherein the data processing unit is installed in a cloud and is configured to

determine the state of the electrolysis cell remotely.

9. The electrolysis device according to any one of claim 1 to claim 8,

wherein the electrolysis cell is configured to produce a carbon compound by

supplying carbon dioxide as the substance to be reduced, or to produce ammonia by

supplying nitrogen as the substance to be reduced.

10. An electrolysis method comprising:

44

21586185_1 (GHMatters) P121160.AU supplying a gas or a liquid containing a substance to be reduced to a cathode part of an electrolysis cell, supplying a liquid containing a substance to be oxidized to an anode part of the electrolysis cell, and operating the electrolysis cell, the electrolysis cell including the cathode part in which a reduction electrode is disposed, the anode part in which an oxidation electrode is disposed, and a diaphragm provided between the cathode part and the anode part; obtaining property data of power that is to be supplied to the electrolysis cell, property data of a gas that is to be input to the electrolysis cell, electric property data of the electrolysis cell, property data of an output gas of the electrolysis cell, and temperature data of the electrolysis cell, all the data being obtained during the operation of the electrolysis cell; processing the property data of the power, the property data of the gas, the electric property data, the property data of the output gas, and the temperature data to obtain an equivalent circuit model and an equivalent circuit parameter of the electrolysis cell, and determining a state of the electrolysis cell, using the equivalent circuit model and the equivalent circuit parameter of the electrolysis cell; and displaying information including the equivalent circuit model, the equivalent circuit parameter, and the determined state.

11. The electrolysis method according to claim 10,

wherein the determining the state of the electrolysis cell comprises determining a

deterioration state of the electrolysis cell, using the equivalent circuit model and the

equivalent circuit parameter.

12. The electrolysis method according to claim 11,

45

21586185_1 (GHMatters) P121160.AU wherein the determining the state of the electrolysis cell comprises calculating the equivalent circuit parameter by fitting, using the obtained data and simulation data of the equivalent circuit model, and detecting a deterioration of the electrolysis cell based on information of the equivalent circuit parameter.

13. The electrolysis method according to claim 11 or claim 12,

wherein the determining the state of the electrolysis cell comprises finding a

deterioration degree of the equivalent circuit parameter, and determining whether to stop

the operation of the electrolysis cell by setting a determination standard for the

deterioration degree, the deterioration degree being represented by [(the equivalent circuit

parameter during the real operation) - (the equivalent circuit parameter before the real

operation or at the design time)]/(the equivalent circuit parameter before the real operation

or at the design time).

14. The electrolysis method according to claim 10,

wherein the obtaining the data of the electrolysis cell comprises obtaining data of

a reference electrolysis cell, and

wherein the electrolysis cell is designed based on the equivalent circuit model and

the equivalent circuit parameter that are derived from the data of the reference electrolysis

cell.

15. The electrolysis method according to claim 14, further comprising:

selecting a candidate for the equivalent circuit model;

calculating the equivalent circuit parameter by fitting such that a square error

between the data of the reference electrolysis cell and simulation data of the selected

equivalent circuit model becomes small; and

46

21586185_1 (GHMatters) P121160.AU determining whether the equivalent circuit parameter is valid, using the square eror between the data of the reference electrolysis cell and the simulation data of the equivalent circuit parameter; and designing the electrolysis cell using the equivalent circuit model and the equivalent circuit parameter determined as valid.

47

21586185_1 (GHMatters) P121160.AU

FIG. 1 1

12

DATA PROCESSING UNIT

11 13 DATA DISPLAY STORAGE UNIT UNIT 3 4 7 SUPPLY POWER 1/12

SUPPLY POWER ELECTRIC CONTROL UNIT PROPERTY PROPERTY OBTAINING UNIT OBTAINING ELECTROLYSIS UNIT GAS/ELECTRORYSIS INPUT GAS CELL SOLUTION PROPERTY (STACK) OUTPUT GAS CONTROL UNIT OBTAINING UNIT PROPERTY 6 OBTAINING (TO VALUABLE TEMPERATURE TEMPERATURE UNIT MANUFACTURING CONTROL UNIT OBTAINING UNIT PART) 2 8 9 10