Apparatus for calculating the degree of cell degradation of an electrochemical cell stack, a cell degradation calculation system, a cell degradation calculation method, and a cell degradation calculation program.

Abstract

To provide a cell degradation degree calculation device for an electrochemical cell stack capable of easily obtaining a cell degradation degree.SOLUTION: A cell degradation degree calculation device for an electrochemical cell stack in an embodiment comprises a first calculation unit for calculating a first target voltage value based on first characteristic data, a second calculation unit for calculating a second target voltage value based on second characteristic data, and a third calculation unit for calculating a cell degradation degree indicating a cell degradation degree based on the first target voltage value and the second target voltage value. The first target voltage value is a voltage value when the reduction rate of the voltage value reaches a first threshold after a second time zone of the first characteristic data has passed. The second target voltage value is the voltage value when the reduction rate of the voltage value reaches a second threshold after a fourth time zone of the second characteristic data has passed.SELECTED DRAWING: Figure 4

Description

Technical Field

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[0001] The embodiments relate to a cell degradation degree calculation device, a cell degradation degree calculation system, a cell degradation degree calculation method, and a cell degradation degree calculation program for an electrochemical cell stack.

Background Art

[0002] An electrochemical cell stack that constitutes a fuel cell, a water electrolysis device, a carbon dioxide electrolysis device, etc. is configured by stacking a plurality of cells. The membrane electrode assembly that constitutes a cell includes an anode electrode, a cathode electrode, and an electrolyte membrane interposed between the anode electrode and the cathode electrode. When the use of the electrochemical cell stack continues, the catalyst materials contained in the anode electrode and the cathode electrode deteriorate, or the electrolyte membrane deteriorates. In this case, the performance of the electrochemical cell stack may decrease.

Prior Art Documents

Patent Documents

[0005] The electrochemical cell stack cell degradation calculation device according to this embodiment is a device for calculating the degradation of cells in an electrochemical cell stack. The electrochemical cell stack cell degradation calculation device comprises: a first acquisition unit that acquires first characteristic data showing the voltage-time characteristics of the cells after carbon dioxide electrolysis is stopped; a second acquisition unit that acquires second characteristic data showing the voltage-time characteristics of the cells after water electrolysis is stopped; a first calculation unit that calculates a first target voltage value based on the first characteristic data; a second calculation unit that calculates a second target voltage value based on the second characteristic data; and a third calculation unit that calculates a cell degradation degree showing the degradation of the cells based on the first target voltage value and the second target voltage value. The voltage-time characteristics when carbon dioxide electrolysis is stopped have a first time period in which the rate of decrease in voltage value increases, and a second time period after the first time period in which the rate of decrease in voltage value decreases. The voltage-time characteristics when water electrolysis is stopped have a third time period in which the rate of decrease in voltage value increases, and a fourth time period after the third time period in which the rate of decrease in voltage value decreases. The first target voltage value is the voltage value at which the rate of decrease in the voltage value reaches a first threshold after the second time period of the first characteristic data has elapsed. The second target voltage value is the same voltage value at which the rate of decrease in the voltage value reaches a second threshold after the fourth time period of the second characteristic data has elapsed.

[0006] The electrochemical cell stack cell degradation degree calculation system according to the embodiment is a system for calculating the degradation degree of cells in an electrochemical cell stack. The electrochemical cell stack cell degradation degree calculation system comprises the electrochemical cell stack degradation degree calculation device described above, a first database for storing first characteristic data, and a second database for storing second characteristic data. The first acquisition unit acquires first characteristic data from the first database. The second acquisition unit acquires second characteristic data from the second database.

[0007] The method for calculating the degree of cell degradation of an electrochemical cell stack according to the embodiment is a method for calculating the degree of cell degradation of an electrochemical cell stack. The method for calculating the degree of cell degradation of an electrochemical cell stack includes the steps of: acquiring first characteristic data showing the voltage-time characteristics of the cell after stopping carbon dioxide electrolysis in the electrochemical cell stack; acquiring second characteristic data showing the voltage-time characteristics of the cell after stopping water electrolysis in the electrochemical cell stack; calculating a first target voltage value based on the first characteristic data; calculating a second target voltage value based on the second characteristic data; and calculating a degree of cell degradation showing the degree of cell degradation based on the first target voltage value and the second target voltage value. The voltage-time characteristics when carbon dioxide electrolysis is stopped have a first time period in which the rate of decrease in voltage value increases, and a second time period after the first time period in which the rate of decrease in voltage value decreases. The voltage-time characteristics when water electrolysis is stopped have a third time period in which the rate of decrease in voltage value increases, and a fourth time period after the third time period in which the rate of decrease in voltage value decreases. The first target voltage value is the voltage value when the rate of decrease in voltage value reaches a first threshold after the second time period of the first characteristic data has elapsed. The second target voltage value is the voltage value at which the rate of decrease in the voltage value reaches the second threshold after the fourth time period of the second characteristic data has elapsed.

[0008] The electrochemical cell stack cell degradation calculation program according to the embodiment is a program that causes a computer to execute an electrochemical cell stack cell degradation calculation method for calculating the degradation of cells in an electrochemical cell stack. The electrochemical cell stack cell degradation calculation program includes the steps of: acquiring first characteristic data showing the voltage-time characteristics of the cells after carbon dioxide electrolysis in the electrochemical cell stack is stopped; acquiring second characteristic data showing the voltage-time characteristics of the cells after water electrolysis in the electrochemical cell stack is stopped; calculating a first target voltage value based on the first characteristic data; calculating a second target voltage value based on the second characteristic data; and calculating a cell degradation degree showing the degradation of the cells based on the first target voltage value and the second target voltage value. The voltage-time characteristics when carbon dioxide electrolysis is stopped have a first time period in which the rate of decrease in voltage value increases, and a second time period after the first time period in which the rate of decrease in voltage value decreases. The voltage-time characteristics when water electrolysis is stopped have a third time period in which the rate of decrease in voltage value increases, and a fourth time period after the third time period in which the rate of decrease in voltage value decreases. The first target voltage value is the voltage value at which the rate of decrease in the voltage value reaches the first threshold after the second time period of the first characteristic data has elapsed. The second target voltage value is the voltage value at which the rate of decrease in the voltage value reaches the second threshold after the fourth time period of the second characteristic data has elapsed. [Effects of the Invention]

[0009] According to this embodiment, the degree of cell degradation can be easily obtained. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a cross-sectional view showing the schematic configuration of the electrochemical cell stack according to this embodiment. [Figure 2] Figure 2 is a plan view showing the cells shown in Figure 1. [Figure 3] Figure 3 shows the schematic system configuration of the electrochemical cell stack shown in Figure 1. [Figure 4]Figure 4 shows the cell degradation degree calculation system for an electrochemical cell stack according to this embodiment. [Figure 5] Figure 5 is a schematic diagram illustrating the first characteristic data stored in the first database shown in Figure 4. [Figure 6] Figure 6 is a schematic diagram illustrating the second characteristic data stored in the second database shown in Figure 4. [Figure 7] Figure 7 is a graph showing the voltage-time characteristics of the cell. [Figure 8] Figure 8 is a diagram illustrating the measurement method used to obtain the characteristic data shown in Figures 5 and 6. [Figure 9] Figure 9 is a flowchart showing the method for calculating the degree of cell degradation of an electrochemical cell stack according to this embodiment. [Modes for carrying out the invention]

[0011] Next, the cell degradation degree calculation device, cell degradation degree calculation system, cell degradation degree calculation method, and cell degradation degree calculation program for an electrochemical cell stack according to this embodiment will be described. Here, we will first describe the electrochemical cell stack according to this embodiment. An electrochemical cell stack is used in electrolysis devices for carbon dioxide or water, or in fuel cells, etc.

[0012] As shown in Figure 1, the electrochemical cell stack 1 comprises a pair of current collector plates 2, a plurality of cells 10 stacked between the pair of current collector plates 2, and a plurality of separators 30 stacked alternately with the cells 10. Each cell 10 includes a membrane electrode assembly (MEA) 10M and a cell frame 20. The cells 10, separators 30, and current collector plates 2 are clamped and pressed together by a pair of clamping plates 3. The pair of clamping plates 3 are clamped together using bolts and nuts (not shown). An insulating plate 4 is interposed between the clamping plates 3 and the current collector plates 2.

[0013] The membrane electrode assembly 10M includes a cathode electrode 11, an anode electrode 12, and an electrolyte membrane 13 interposed between the cathode electrode 11 and the anode electrode 12. The membrane electrode assembly 10M is formed in a thin plate shape. The membrane electrode assembly 10M may be formed in a rectangular shape when viewed in the stacking direction D of the electrochemical cell stack 1.

[0014] The cathode electrode 11 includes a cathode catalyst layer 11a and a cathode gas diffusion layer 11b. The cathode catalyst layer 11a is in contact with the electrolyte membrane 13. The cathode gas diffusion layer 11b is in contact with the separator 30 and diffuses the cathode fluid supplied from the cathode flow path described later. When the electrochemical cell stack 1 is used in an electrolysis device, the cathode gas diffusion layer 11b may be formed of, for example, carbon paper or titanium non-woven fabric. The cathode gas diffusion layer 11b is joined to the cathode catalyst layer 11a. If the cathode catalyst layer 11a can diffuse the cathode fluid, the cathode gas diffusion layer 11b may not be provided.

[0015] The anode electrode 12 includes an anode catalyst layer 12a and an anode gas diffusion layer 12b. The anode catalyst layer 12a is in contact with the electrolyte membrane 13. The anode catalyst layer 12a is in contact with the electrolyte membrane 13. The anode gas diffusion layer 12b is in contact with the separator 30 and diffuses the anode fluid supplied from the anode flow path 32 described later. When the electrochemical cell stack 1 is used in an electrolysis device, the anode gas diffusion layer 12b may be formed of, for example, carbon paper or titanium non-woven fabric. The anode gas diffusion layer 12b is joined to the anode catalyst layer 12a. If the anode catalyst layer 12a can diffuse the anode fluid, the anode gas diffusion layer 12b may not be provided.

[0016] The electrolyte membrane 13 is formed of an electrolyte material. When the electrochemical cell stack 1 is used in an electrolysis device, examples of the electrolyte membrane 13 include, but are not limited to, ion exchange membranes or porous membranes.

[0017] The anode electrode 12 is formed on one side of the electrolyte membrane 13, and the cathode electrode 11 is formed on the other side of the electrolyte membrane 13. The anode electrode 12 and the cathode electrode 11 are bonded to the electrolyte membrane 13.

[0018] When the electrochemical cell stack 1 is used as a fuel cell, a power generation reaction is carried out to produce electrical energy. In this case, a cathode fluid (see symbol F1 in Figure 1) is supplied to the cathode electrode 11 from the cathode channel 31, which will be described later. The cathode fluid is an oxygen-containing gas, and may be air, for example. An anode fluid (see symbol F2 in Figure 1) is supplied to the anode electrode 12 from the anode channel 32, which will be described later. The anode fluid may be a hydrogen-containing gas, for example. When the cathode fluid and anode fluid are supplied, an electrochemical reaction occurs in the membrane electrode assembly 10M. As a result, electrical energy can be extracted.

[0019] When the electrochemical cell stack 1 is used as an electrolysis apparatus, the electrolysis reaction is carried out using electrical energy. In this case, the cathode fluid may be water vapor or carbon dioxide gas, and the water vapor or carbon dioxide gas may be electrolyzed at the cathode electrode. An electrolytic solution may be supplied to the anode electrode 12. The electrolytic solution may be an aqueous solution containing an electrolyte such as calcium bicarbonate (KHCO3).

[0020] As shown in Figure 2, the cell 10 is marked with an identification symbol 14 indicating identification information. The identification information may be an ID code. The identification symbol 14 may be affixed to the surface of the cathode electrode 11 facing the cathode channel 31, or to the surface of the anode electrode 12 facing the anode channel 32. The identification symbol 14 may also be affixed to the margin portion. The margin portion is located outside the seal portion (not shown) of the cell frame 20, which will be described later. The identification symbol 14 may be affixed to the cell frame 20 by, for example, printing, laser, or handwriting. The identification symbol 14 may be affixed to the cell frame 20 using alphanumeric characters, or it may be affixed to the cell frame 20 using a one-dimensional barcode or a two-dimensional barcode.

[0021] As shown in Figure 2, when viewed in the stacking direction D of the electrochemical cell stack 1, the membrane electrode assembly 10M is surrounded by the cell frame 20. The cell frame 20 may be made of a plastic film. Examples of materials that can be used for the plastic film include polyethylene, polypropylene, polyethylene terephthalate, polystyrene, polycarbonate, polyurethane, phenolic resin, polyimide, polyamide, melamine resin, polyethylene naphthalate, polyacetal, ABS resin, polyether ethyl ketone, polyphenylene ether, polyvinyl acetate, and fluororesin. The cell frame 20 is impermeable to the anode fluid and cathode fluid.

[0022] The cell frame 20 includes an opening 20a. A membrane electrode assembly 10M is inserted into this opening 20a and bonded with an adhesive. The adhesive can be acrylic, epoxy, polyethylene, polypropylene, polyester, polyolefin, urethane, polyvinyl acetate, or the like.

[0023] The cell frame 20 is provided with a cathode fluid supply port 21, an anode fluid supply port 22, a cathode fluid outlet port 23, and an anode fluid outlet port 24. In other words, the electrochemical cell stack 1 according to this embodiment has an internal manifold structure. Each fluid supply port 21, 22 and each fluid outlet port 23, 24 penetrates the cell frame 20. Each fluid supply port 21, 22 is located on one side of the membrane electrode assembly 10M, and each fluid outlet port 23, 24 is located on the other side of the membrane electrode assembly 10M.

[0024] The separator 30 is both conductive and gas-impermeable. The separator 30 separates the atmosphere of the anode fluid from the atmosphere of the cathode fluid.

[0025] As shown in Figure 1, the separator 30 includes a plurality of cathode channels 31 and a plurality of anode channels 32. The cathode channels 31 are formed on the side of the separator 30 facing the cathode electrode 11, and the cathode fluid flowing through the cathode channels 31 is supplied to the cathode electrode 11. The cathode channels 31 may have a straight channel structure, a serpentine channel structure, or a crank channel structure, and are optional. The anode channels 32 are formed on the side of the separator 30 facing the anode electrode 12, and the anode fluid flowing through the anode channels 32 is supplied to the anode electrode 12. The anode channels 32 may have a straight channel structure, a serpentine channel structure, or a crank channel structure, and are optional.

[0026] Similar to the cell frame 20 described above, the separator 30 has a cathode fluid supply port 33 (see Figure 8), an anode fluid supply port 34, a cathode fluid outlet port 35, and an anode fluid outlet port 36. The cathode fluid flows from the cathode fluid supply port 33 through the cathode flow path 31 to the cathode fluid outlet port 35. The anode fluid flows from the anode fluid supply port 34 through the anode flow path 32 to the anode fluid outlet port 36. The separator 30 may be formed by pressing a thin metal film or by injection molding of a carbon material, and this is optional.

[0027] The separator 30 is not joined to the cell 10, but is pressed against the cell 10 by the pressing force of the clamping plate 3 as described above, as shown in Figure 1.

[0028] The electrochemical cell stack 1 configured in this way can be disassembled after operation. More specifically, first, the bolts and nuts that fastened the clamping plate 3 are removed. Then, the clamping plate 3, insulating plate 4, and current collector plate 2 located at the top of the electrochemical cell stack 1 are removed. Next, the separator 30 and the cells 10 are removed sequentially, and each cell 10 is separated. In this way, the cells 10 equipped with the membrane electrode assembly 10M can be removed.

[0029] Figure 3 shows an example of an electrochemical cell stack system 100 equipped with the electrochemical cell stack 1 described above. The electrochemical cell stack system 100 shown in Figure 3 may include the electrochemical cell stack 1, an auxiliary device 101, a power converter 102, and a control device 103.

[0030] The electrochemical cell stack 1 can be started and operated by the auxiliary equipment 101. When the electrochemical cell stack 1 is used as a fuel cell, the auxiliary equipment 101 supplies hydrogen gas and air to the fuel cell. The auxiliary equipment 101 consists of, for example, a blower. While the fuel cell is operating, the auxiliary equipment 101 is supplied with operating power from the commercial grid. The power generated by the fuel cell is converted from DC current to AC current by the power converter 102 and supplied to the external load. When the electrochemical cell stack 1 is used as an electrolysis apparatus, the auxiliary equipment 101 supplies steam or carbon dioxide gas and an electrolytic solution to the electrolysis apparatus. The power used for electrolysis is supplied from the commercial grid through the power converter 102. The power converter 102 converts the power from the commercial grid from AC current to DC current and supplies it to the electrolysis apparatus. The auxiliary equipment 101 and the power converter 102 are controlled by the control device 103.

[0031] Next, the cell degradation degree calculation system 40 of the electrochemical cell stack 1 according to this embodiment will be described. The cell degradation degree calculation system 40 is a system for calculating the cell degradation degree of the cells 10 of the electrochemical cell stack 1.

[0032] As shown in Figure 4, the cell degradation degree calculation system 40 of the electrochemical cell stack 1 according to this embodiment may include a first database 41, a second database 42, and a cell degradation degree calculation device 50. Each of the databases 41, 42 and the cell degradation degree calculation device 50 are connected by a network N such as a LAN (Local Area Network). In this embodiment, the first database 41 and the second database 42 are connected to the cell degradation degree calculation device 50.

[0033] As shown in Figure 5, the first database 41 stores first characteristic data showing the voltage-time characteristics of cell 10 after carbon dioxide electrolysis has stopped. The first database 41 may store first characteristic data for multiple cells 10. Identification information is assigned to each first characteristic data, and each first characteristic data is associated with the identification information. The first characteristic data consists of multiple combinations of corresponding time and voltage values. Details of the first characteristic data will be described later. If the identification information is an ID code, consecutive ID codes may be assigned to each cell 10, as shown in Figure 5. However, the numbering of the ID codes assigned to each cell 10 is arbitrary as long as it has an identification function. The first database 41 may be recorded on a cloud server. The first characteristic data may be stored in the first database 41 by being recorded on the cloud server when measured.

[0034] As shown in Figure 6, the second database 42 stores second characteristic data showing the voltage-time characteristics of cell 10 after water electrolysis has stopped. The second database 42 may store second characteristic data for multiple cells 10. Each second characteristic data is assigned identification information, and each second characteristic data is associated with the identification information. The second characteristic data consists of multiple combinations of corresponding time and voltage values. Details of the second characteristic data will be described later. The second database 42 may be recorded on a cloud server. The second characteristic data may be stored in the second database 42 by being recorded on the cloud server when measured.

[0035] Next, the cell degradation degree calculation device 50 according to this embodiment will be described. The cell degradation degree calculation device 50 is a device for calculating the cell degradation degree of the cells 10 of the electrochemical cell stack 1.

[0036] As shown in Figure 4, the cell degradation degree calculation device 50 may include an input unit 51, a display unit 52, a storage unit 53, a communication unit 54, and a calculation unit 60. The input unit 51 is configured to input information and may consist of, for example, a keyboard, mouse, or touch panel. The display unit 52 is configured to display information and may consist of, for example, a display. The display unit 52 may display display information created by a display information creation unit 67, which will be described later. The storage unit 53 is configured to store information and may consist of, for example, a memory or storage device. The communication unit 54 may be configured to communicate with an external device that stores databases 41 and 42 via a network N. For example, the communication unit 54 may consist of a communication interface.

[0037] As shown in Figure 4, the calculation unit 60 may include functional blocks such as a first acquisition unit 61, a second acquisition unit 62, a first calculation unit 63, a second calculation unit 64, a third calculation unit 65, a determination unit 66, and a display information creation unit 67. These functional blocks may be implemented, for example, by the calculation unit 60 executing a computer program stored in the storage unit 53. This program is an example of a design program for the electrochemical cell stack 1 and may be installed on the cell degradation degree calculation device 50 from a recording medium. Alternatively, the cell degradation degree calculation program may be downloaded to the cell degradation degree calculation device 50 from a server on the network N or the like.

[0038] The first acquisition unit 61 acquires first characteristic data showing the voltage-time characteristics of cell 10 after carbon dioxide electrolysis has stopped. The first characteristic data, along with associated identification information, is acquired from the first database 41 described above. The first acquisition unit 61 is configured to acquire the first characteristic data from the first database 41 via the communication unit 54 and the network N.

[0039] The second acquisition unit 62 acquires second characteristic data showing the voltage-time characteristics of cell 10 after water electrolysis has stopped. The second characteristic data, along with associated identification information, is acquired from the second database 42 described above. The second acquisition unit 62 is configured to acquire the second characteristic data from the second database 42 via the communication unit 54 and the network N.

[0040] The first calculation unit 63 calculates the first target voltage value. The first target voltage value V1 is calculated based on the first characteristic data.

[0041] As shown by the solid line in Figure 7, the first characteristic data may be data showing the voltage-time characteristics obtained after carbon dioxide electrolysis has been performed and stopped in a carbon dioxide electrolysis apparatus equipped with an electrochemical cell stack 1. In Figure 7, carbon dioxide electrolysis is performed until time t0, at which time t0 the carbon dioxide electrolysis is stopped. After time t0, the cessation of carbon dioxide electrolysis continues, and the voltage value of cell 10 is shown to be decreasing.

[0042] The voltage-time characteristics after carbon dioxide electrolysis is stopped have a first time period T1 in which the rate of decrease in voltage increases, and a second time period T2 in which the rate of decrease in voltage decreases after the first time period, as shown by the solid line in Figure 7. The first target voltage value is the voltage value when the rate of decrease in voltage reaches a first threshold after the second time period T2 of the first characteristic data has elapsed. In the second time period, the rate of decrease in voltage gradually decreases, and thereafter the voltage value becomes almost constant. The first threshold may be set as the rate of decrease in voltage at which the voltage value can be considered constant. The first calculation unit 63 may calculate a third characteristic curve as shown in Figure 7 using the time and voltage values ​​that constitute the first characteristic data, and the voltage value at which the rate of decrease in voltage reaches the first threshold on this third characteristic curve may be set as the first target voltage value. An example of a third characteristic curve is shown by the solid line in Figure 7.

[0043] The second calculation unit 64 calculates the second target voltage value. The second target voltage value V2 is calculated based on the second characteristic data.

[0044] As shown by the dashed line in Figure 7, the second characteristic data may be data showing the voltage-time characteristics obtained after water electrolysis has been performed and stopped in a carbon dioxide electrolysis apparatus equipped with an electrochemical cell stack 1. In Figure 7, water electrolysis is performed until time t0, at which point water electrolysis is stopped. After time t0, the cessation of water electrolysis continues, and the voltage value of cell 10 is shown to be decreasing.

[0045] The voltage-time characteristics after water electrolysis is stopped have a third time period T3 in which the rate of decrease in voltage increases, and a fourth time period T4 in which the rate of decrease in voltage decreases after the third time period, as shown by the dashed line in Figure 7. The second target voltage value is the voltage value when the rate of decrease in voltage reaches the second threshold after the fourth time period T4 of the second characteristic data has elapsed. In the fourth time period, the rate of decrease in voltage gradually decreases, and thereafter the voltage value becomes almost constant. The second threshold may be set as the rate of decrease in voltage at which the voltage value can be considered constant. The second calculation unit 64 may calculate a fourth characteristic curve as shown in Figure 7 using the time and voltage values ​​that constitute the second characteristic data, and the voltage value at which the rate of decrease in voltage reaches the second threshold on this fourth characteristic curve may be set as the second target voltage value. An example of a fourth characteristic curve is shown by the dashed line in Figure 7.

[0046] The third calculation unit 65 calculates the degree of cell degradation based on the first target voltage value and the second target voltage value. The degree of cell degradation indicates the degree of degradation of cell 10. For example, the second calculation unit 64 may calculate the degree of cell degradation by dividing the difference obtained by subtracting the second target voltage value from the first target voltage value by the first target voltage value. That is, if the first target voltage value is V1 and the second target voltage value is V2, the degree of cell degradation α may be calculated according to the following formula (1).

number

[0047] The determination unit 66 may determine whether the cell degradation level calculated by the third calculation unit 65 is equal to or greater than the degradation level threshold. In this case, the degree of degradation of cell 10 can be determined. The degradation level threshold may be, for example, a value that indicates relatively severe degradation. If the cell degradation level is relatively severe, the cell degradation level will be high. Alternatively, the degradation level threshold may be, for example, a value that indicates a short circuit has occurred in cell 10. If a short circuit has occurred, the difference between the first target voltage value V1 and the second target voltage value V2 will be high, and the cell degradation level will be high.

[0048] The display information creation unit 67 creates display information including the cell degradation degree calculated by the third calculation unit 65. The display information may also include the cell degradation degree determination result by the determination unit 66. The display information created by the display information creation unit 67 may be displayed by the display unit 52 described above.

[0049] Next, we will explain how to create the first and second characteristic data. Here, we will explain using the example where the electrochemical cell stack 1 shown in Figure 1 constitutes a carbon dioxide electrolysis device.

[0050] As shown in Figure 8, the electrochemical cell stack 1 is equipped with multiple measuring pins 70 to measure the voltage applied to the cell 10. The measuring pins 70 for the cathode electrode 11 may be inserted into cathode-side recesses 37 formed on the surface of the separator 30 facing the cathode electrode 11. The cathode-side recesses 37 are formed in a different location from the cathode channel 31 formed on the surface in Figure 8. For convenience, the cathode channel 31 is simplified in Figure 8. The measuring pins 70 inserted into the cathode-side recesses 37 can electrically contact the cathode electrode 11. The measuring pins 70 for the anode electrode 12 may be inserted into anode-side recesses 38 formed on the surface of the separator 30 facing the anode electrode 12. The anode-side recesses 38 are formed in a different location from the anode channel 32 formed on the back surface in Figure 8. The measuring pins 70 inserted into the anode-side recesses 38 can electrically contact the anode electrode 12. Figure 8 shows a typical measurement state for one cell 10, but measurement pins 70 are inserted into the cathode-side recess 37 and anode-side recess 38 of each separator 30 in order to measure the voltage value for each cell 10 that makes up the electrochemical cell stack 1. In other words, measurements may be performed using two measurement pins 70 for one cell 10.

[0051] Each measuring pin 70 for the cathode electrode 11 and each measuring pin 70 for the anode electrode 12 are connected to the measuring device 72 via an electrical wire 71. The electrical wire 71 electrically connects the measuring pins 70 to the measuring device 72. If the electrochemical cell stack 1 has an internal manifold structure, the measuring pins 70 are hermetically attached to the separator 30 using a sealing material (not shown). This prevents leakage of fluids such as cathode fluid and anode fluid. The electrical wire 71 passes through a housing (not shown) and is connected to the measuring device 72 located externally.

[0052] The measuring device 72 measures the voltage value of each cell 10. The measuring device 72 is connected to the first database 41 and the second database 42 described above via the network N. The voltage value and measurement time measured by the measuring device 72 are associated with the identification information of the corresponding cell 10 and transmitted to the first database 41. As shown in Figure 5, the voltage value and time are stored in the first database 41 as first characteristic data. The first database 41 stores multiple first characteristic data corresponding to each cell 10. Each first characteristic data is associated with the identification information of the corresponding cell 10.

[0053] The first characteristic data may be data showing the voltage-time characteristics of cell 10 after carbon dioxide electrolysis has stopped in a carbon dioxide electrolysis apparatus equipped with an electrochemical cell stack 1. During carbon dioxide electrolysis, carbon dioxide gas as cathode fluid F1 as shown in Figure 1 is supplied to the cathode electrode 11, and an electrolytic solution (such as calcium bicarbonate) as anode fluid F2 is supplied to the anode electrode 12. Carbon dioxide electrolysis is performed in the membrane electrode assembly 10M, carbon monoxide is generated at the cathode electrode 11 and discharged from the cathode electrode 11. Oxygen gas is generated at the anode electrode 12 and discharged from the anode electrode 12.

[0054] The measurements for creating the first characteristic data are performed after carbon dioxide electrolysis has been stopped. After stopping, the voltage value is measured along with the measurement time. This yields the first characteristic data showing the voltage-time characteristics after stopping carbon dioxide electrolysis, as shown by the solid line in Figure 7. In other words, the first characteristic data can be obtained without disassembling the electrochemical cell stack 1.

[0055] The second characteristic data may be data showing the voltage-time characteristics of cell 10 after water electrolysis has stopped in a carbon dioxide electrolysis apparatus equipped with an electrochemical cell stack 1. During water electrolysis, water as the cathode fluid F1 shown in Figure 1 is supplied to the cathode electrode 11, and the electrolytic solution (such as calcium bicarbonate) as the anode fluid F2 is supplied to the anode electrode 12. Water electrolysis is performed in the membrane electrode assembly 10M, hydrogen gas is generated at the cathode electrode 11 and discharged from the cathode electrode 11. Oxygen gas is generated at the anode electrode 12 and discharged from the anode electrode 12.

[0056] The measurements for creating the second characteristic data are performed after water electrolysis has been stopped. Water electrolysis may be performed after or before the creation of the first characteristic data. After stopping, the voltage value is measured along with the measurement time. This yields the first characteristic data, which shows the voltage-time characteristics after stopping water electrolysis, as shown by the dashed line in Figure 7. In other words, the first characteristic data can be obtained without disassembling the electrochemical cell stack 1.

[0057] Next, the method for calculating the degree of cell degradation of the electrochemical cell stack 1 according to this embodiment will be explained with reference to Figure 9.

[0058] First, in step S1, the first acquisition unit 61 acquires first characteristic data showing the voltage-time characteristics of cell 10 after carbon dioxide electrolysis has stopped. For example, as shown in Figure 5, first characteristic data corresponding to any one cell 10 is acquired from the first characteristic data stored in the first database 41.

[0059] In step S2, the second acquisition unit 62 acquires second characteristic data showing the voltage-time characteristics of cell 10 after water electrolysis has stopped. For example, as shown in Figure 6, second characteristic data corresponding to cell 10 associated with common identification information with the first characteristic data is acquired from the second characteristic data stored in the second database 42. In the example shown in Figure 9, step S2 is performed after step S1. However, step S2 may be performed before step S1, or simultaneously with step S1.

[0060] Following step S2, in step S3, the first calculation unit 63 calculates a first target voltage value V1 (see Figure 7) based on the first characteristic data acquired in step S1.

[0061] In step S4, the second calculation unit 64 calculates the second target voltage value V2 (see Figure 7) based on the second characteristic data acquired in step S2. In the example shown in Figure 9, step S4 is performed after step S3. However, step S4 may be performed before step S3, or simultaneously with step S3.

[0062] After step S4, in step S5, the third calculation unit 65 calculates the degree of cell degradation based on the first target voltage value calculated in step S3 and the second target voltage value calculated in step S4. The third calculation unit 65 may also calculate the degree of cell degradation using the above-described formula (1).

[0063] After step S5, in step S6, the determination unit 66 determines whether the cell degradation level calculated in step S5 is equal to or greater than the degradation threshold. If the cell degradation level is equal to or greater than the degradation threshold, it may be assumed that a short circuit has occurred in the corresponding cell 10.

[0064] Following step S6, in step S7, the display information creation unit 67 creates display information that includes the cell degradation degree calculated in step S5 and the judgment result from step S6. The created display information may be displayed on the display unit 52.

[0065] To calculate the cell degradation degree of a cell 10 different from the cell 10 from which the above-mentioned cell degradation degree was calculated, the first characteristic data of the other cell 10 is obtained in step S1, the second characteristic data of the same cell 10 is obtained in step S2, and then steps S3 to S7 are performed. By performing steps S1 to S7 described above for each cell 10, the cell degradation degree can be calculated for multiple cells 10.

[0066] As described above, according to this embodiment, a first target voltage value is calculated based on first characteristic data showing the voltage-time characteristics of cell 10 after carbon dioxide electrolysis has stopped, and a second target voltage value is calculated based on second characteristic data showing the voltage-time characteristics of cell 10 after water electrolysis has stopped. Based on the first target voltage value and the second target voltage value, the degree of cell degradation of cell 10 is calculated. As a result, the degree of cell degradation of cell 10 can be calculated simply by using the first target voltage value and the second target voltage value. Therefore, the degree of cell degradation can be easily obtained.

[0067] Furthermore, according to this embodiment, the degree of cell degradation is calculated by dividing the difference obtained by subtracting the second target voltage value from the first target voltage value by the first target voltage value. This makes it possible to easily calculate the degree of cell degradation of cell 10.

[0068] Furthermore, according to this embodiment, it is determined whether the degree of cell degradation is above a degradation threshold. This makes it possible to select cells 10 that are relatively severely degraded. Also, if the degradation threshold is set to a value that can be considered to indicate the occurrence of a short circuit, it is possible to determine whether a short circuit has occurred in cell 10.

[0069] In the embodiment described above, an example was described in which the electrochemical cell stack 1 has an internal manifold structure. However, the embodiment is not limited to this. For example, the electrochemical cell stack 1 may have an external manifold structure. In this case, the cell frame 20 is not used, and a manifold forming the flow path for each gas is provided on the outer surface of the laminate in which the membrane electrode assembly 10M and the separator 30 are stacked.

[0070] Furthermore, in the embodiment described above, an example was described in which a single separator 30 including a cathode channel 31 and an anode channel 32 is interposed between the two cells 10. However, the embodiment is not limited to this. For example, a cathode-side separator including a cathode channel and an anode-side separator including an anode channel may be interposed between the two cells 10. A cooling water channel (not shown) may be formed between the cathode-side separator and the anode-side separator.

[0071] According to the embodiments described above, the degree of cell degradation can be easily obtained.

[0072] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. Naturally, these embodiments can also be combined in part as appropriate within the scope of the spirit of the invention. [Explanation of Symbols]

[0073] 1: Electrochemical cell stack, 40: Cell degradation degree calculation system, 50: Cell degradation degree calculation device, 61: First acquisition unit, 62: Second acquisition unit, 63: First calculation unit, 64: Second calculation unit, 65: Third calculation unit, 66: Determination unit

Claims

1. An electrochemical cell stack cell degradation degree calculation device for calculating the degree of degradation of cells in an electrochemical cell stack, A first acquisition unit acquires first characteristic data showing the voltage-time characteristics of the cell after carbon dioxide electrolysis has stopped, A second acquisition unit acquires second characteristic data showing the voltage-time characteristics of the cell after water electrolysis has stopped, A first calculation unit calculates a first target voltage value based on the first characteristic data, A second calculation unit calculates a second target voltage value based on the second characteristic data, The system includes a third calculation unit that calculates a cell degradation degree indicating the degree of degradation of the cell based on the first target voltage value and the second target voltage value, When carbon dioxide electrolysis is stopped, the voltage-time characteristics include a first time period in which the rate of decrease in the voltage value increases, and a second time period in which the rate of decrease in the voltage value decreases after the first time period. When the water electrolysis is stopped, the voltage-time characteristics include a third time period in which the rate of decrease in the voltage value increases, and a fourth time period in which the rate of decrease in the voltage value decreases after the third time period. The first target voltage value is the voltage value at which the rate of decrease of the voltage value reaches a first threshold after the second time period of the first characteristic data has elapsed. The second target voltage value is the voltage value at which the rate of decrease of the voltage value reaches the second threshold after the fourth time period of the second characteristic data has elapsed. A device for calculating the degree of cell degradation in an electrochemical cell stack.

2. The third calculation unit calculates the degree of cell degradation by dividing the difference obtained by subtracting the second target voltage value from the first target voltage value by the first target voltage value. A device for calculating the degree of cell degradation of an electrochemical cell stack according to claim 1.

3. The system further includes a determination unit that determines whether the cell degradation level calculated by the third calculation unit is equal to or greater than a degradation threshold. A device for calculating the degree of cell degradation of an electrochemical cell stack according to claim 1.

4. An electrochemical cell stack cell degradation calculation system for calculating the degree of degradation of cells in an electrochemical cell stack, A device for calculating the degree of cell degradation of an electrochemical cell stack according to claim 1 or 2, A first database for storing the first characteristic data, The system comprises a second database for storing the second characteristic data, The first acquisition unit acquires the first characteristic data from the first database, The second acquisition unit acquires the second characteristic data from the second database. A system for calculating the degree of cell degradation in electrochemical cell stacks.

5. A method for calculating the degree of cell degradation in an electrochemical cell stack, wherein the degree of cell degradation in an electrochemical cell stack is calculated, The steps include: acquiring first characteristic data showing the voltage-time characteristics of the cell after stopping carbon dioxide electrolysis in the electrochemical cell stack; The steps include: acquiring second characteristic data showing the voltage-time characteristics of the cell after stopping the water electrolysis in the electrochemical cell stack; A step of calculating a first target voltage value based on the first characteristic data, A step of calculating a second target voltage value based on the second characteristic data, The process includes the step of calculating a cell degradation degree indicating the degree of degradation of the cell based on the first target voltage value and the second target voltage value, When carbon dioxide electrolysis is stopped, the voltage-time characteristics include a first time period in which the rate of decrease in the voltage value increases, and a second time period in which the rate of decrease in the voltage value decreases after the first time period. When the water electrolysis is stopped, the voltage-time characteristics include a third time period in which the rate of decrease in the voltage value increases, and a fourth time period in which the rate of decrease in the voltage value decreases after the third time period. The first target voltage value is the voltage value at which the rate of decrease of the voltage value reaches a first threshold after the second time period of the first characteristic data has elapsed. The second target voltage value is the voltage value at which the rate of decrease of the voltage value reaches the second threshold after the fourth time period of the second characteristic data has elapsed. Method for calculating the degree of cell degradation in an electrochemical cell stack.

6. An electrochemical cell stack cell degradation calculation program that causes a computer to execute a method for calculating the degree of degradation of cells in an electrochemical cell stack, The steps include: acquiring first characteristic data showing the voltage-time characteristics of the cell after stopping carbon dioxide electrolysis in the electrochemical cell stack; The steps include: acquiring second characteristic data showing the voltage-time characteristics of the cell after stopping the water electrolysis in the electrochemical cell stack; A step of calculating a first target voltage value based on the first characteristic data, A step of calculating a second target voltage value based on the second characteristic data, The process includes the step of calculating a cell degradation degree indicating the degree of degradation of the cell based on the first target voltage value and the second target voltage value, When carbon dioxide electrolysis is stopped, the voltage-time characteristics include a first time period in which the rate of decrease in the voltage value increases, and a second time period in which the rate of decrease in the voltage value decreases after the first time period. When the water electrolysis is stopped, the voltage-time characteristics include a third time period in which the rate of decrease in the voltage value increases, and a fourth time period in which the rate of decrease in the voltage value decreases after the third time period. The first target voltage value is the voltage value at which the rate of decrease of the voltage value reaches a first threshold after the second time period of the first characteristic data has elapsed. The second target voltage value is the voltage value at which the rate of decrease of the voltage value reaches the second threshold after the fourth time period of the second characteristic data has elapsed. A program for calculating the degree of cell degradation in an electrochemical cell stack.

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