Aging device and aging method

Abstract

To provide an aging method for eliciting desired power generation performance after assembly of a fuel cell stack.SOLUTION: An aging unit 38 performs non-power generation aging and performance evaluation on a fuel cell stack, and a proton resistance acquisition unit 98 acquires the first proton resistance of a target cell when non-power generation aging is being performed, acquires the second proton resistance of the target cell after performance evaluation, and acquires the third proton resistance, which is a value corresponding to the difference between the first proton resistance of the target cell and the second proton resistance of the target cell.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to an aging device and an aging method. [Background technology]

[0002] In recent years, research and development into fuel cells has been conducted to contribute to energy efficiency, ensuring that more people have access to affordable, reliable, sustainable and advanced energy. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-069754 Summary of the Invention [Problem to be solved by the invention]

[0004] In fuel cell technology, after assembling a fuel cell stack by stacking multiple cells, the fuel cell stack is aged to extract the desired power generation performance. However, there is room for improvement in the aging of fuel cell stacks.

[0005] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0006] A first aspect of the present disclosure is an aging device for aging a polymer electrolyte fuel cell stack having a plurality of cells, the aging device comprising: an aging unit that supplies an anode gas and a cathode gas to the fuel cell stack to perform the aging; and a proton resistance acquisition unit that acquires the proton resistance of a target cell that is at least one of the cells of the fuel cell stack, wherein the aging unit performs a non-power generation process, in which the fuel cell stack is aged in a non-power generation state in which the fuel cell stack is not generating power, by supplying hydrogen gas as the anode gas and an inert gas as the cathode gas; and a proton resistance acquisition unit that acquires the proton resistance of a target cell that is at least one of the cells of the fuel cell stack, the aging unit performing a non-power generation process, in which the fuel cell stack is aged in a non-power generation state in which the fuel cell stack is not generating power, by supplying the hydrogen gas as the anode gas and an inert gas as the cathode gas after the non-power generation process, The aging device is capable of executing a power generation process that causes the fuel cell stack to generate power, and a power generation stop process that places the fuel cell stack in a power generation stopped state by supplying the inert gas as the cathode gas after the power generation process, and the proton resistance acquisition unit is capable of executing a first proton resistance acquisition process that acquires the proton resistance of the target cell as a first proton resistance when the non-power generation aging is being performed on the fuel cell stack, a second proton resistance acquisition process that acquires the proton resistance of the target cell as a second proton resistance when the fuel cell stack is in the power generation stopped state, and a third proton resistance acquisition process that acquires a third proton resistance that is a value corresponding to the difference between the first proton resistance of the target cell and the second proton resistance of the target cell.

[0007] A second aspect of the present disclosure is an aging method for aging a polymer electrolyte fuel cell stack having a plurality of cells, the method comprising: a non-power generation step of performing non-power generation aging on the fuel cell stack in a non-power generation state in which the fuel cell stack is not generating power by supplying hydrogen gas as an anode gas and an inert gas as a cathode gas; a first proton resistance acquisition step of acquiring, as a first proton resistance, the proton resistance of at least one target cell of the fuel cell stack while the non-power generation aging is being performed on the fuel cell stack; and after the first proton resistance acquisition step, acquiring the proton resistance of the target cell. the aging method includes a power generation step of causing the fuel cell stack to generate power by supplying the hydrogen gas as the inert gas and an oxygen-containing gas as the cathode gas; a power generation stop step of bringing the fuel cell stack into a power generation stopped state by supplying the inert gas as the cathode gas after the power generation step; a second proton resistance acquisition step of acquiring the proton resistance of the target cell when the fuel cell stack is in the power generation stopped state as a second proton resistance; and a third proton resistance acquisition unit that acquires a third proton resistance which is a value corresponding to the difference between the first proton resistance of the target cell and the second proton resistance of the target cell. [Effects of the Invention]

[0008] The present invention can provide a better aging device and aging method. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a fuel cell stack according to the first embodiment. [Figure 2] FIG. 2 is a schematic diagram of a cell in the first embodiment. [Figure 3] FIG. 3 is a schematic diagram of the aging device in the first embodiment. [Figure 4] FIG. 4 is a control block diagram of the aging device in the first embodiment. [Figure 5] FIG. 5 is a diagram showing an equivalent circuit of a cell in the first embodiment. [Figure 6] Figure 6 is a Nyquist plot showing the impedance of the cell obtained from the equivalent circuit. [Figure 7] FIG. 7 is an image diagram of a cell when CV aging is being performed on a fuel cell stack. [Figure 8] FIG. 8 is an image diagram of a cell when a performance evaluation is being carried out on a fuel cell stack. [Figure 9] FIG. 9 is a time chart showing the change in proton resistance of a target cell due to aging in a fuel cell stack. [Figure 10] FIG. 10 is a cyclic voltammogram. [Figure 11] FIG. 11 is a flowchart of the aging process executed by the control unit in the first embodiment. [Figure 12] FIG. 12 is a time chart showing the change in proton resistance of the cells due to aging in a fuel cell stack. [Figure 13] FIG. 13 is a flowchart of the aging process executed by the control unit in the second embodiment. [Figure 14] FIG. 14 is a control block diagram of the aging device according to the third embodiment. [Figure 15] FIG. 15 is a map for determining the amount of water produced in a cell from the proton resistance of the cell in the third embodiment. [Figure 16] FIG. 16 is a time chart showing the change in the amount of water produced due to aging in the third embodiment. [Figure 17] FIG. 17 is a flowchart of the aging process executed by the control unit in the third embodiment. [Figure 18] FIG. 18 is a flowchart of the aging process in the fourth embodiment. [Figure 19]FIG. 19 is a time chart showing the change in proton resistance due to aging in the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] After assembling a fuel cell stack by stacking multiple cells, the fuel cell stack is aged to achieve the desired power generation performance. Aging the fuel cell stack activates the catalyst (platinum) in the electrode catalyst layer of each cell.

[0011] Whether the catalyst has been activated can be determined based on the impedance of each cell. However, in the past, the impedance of each cell was measured after the aging process for the fuel cell stack was completed, so it was not possible to set the end time of the aging process based on the impedance of each cell.

[0012] In the present disclosure, by performing aging on the fuel cell stack and measuring the impedance of each cell in the same process, it is possible to set the end time of aging based on the impedance of each cell.

[0013] [First embodiment] [Fuel cell stack configuration] 1 is a schematic diagram of a fuel cell stack 10 according to a first embodiment. The fuel cell stack 10 is mounted on a vehicle such as a fuel cell automobile. The fuel cell stack 10 may also be mounted on equipment other than a vehicle.

[0014] The fuel cell stack 10 is a polymer electrolyte fuel cell. The fuel cell stack 10 generates electricity through an electrochemical reaction between a fuel gas and an oxidant gas. The fuel gas is, for example, hydrogen gas. The fuel gas is not particularly limited as long as it is a gas containing hydrogen. The oxidant gas is, for example, air. The oxidant gas is not particularly limited as long as it is a gas containing oxygen. The fuel cell stack 10 is formed by stacking a plurality of cells 14.

[0015] [Cell Configuration] 2 is a schematic diagram of a cell 14 in the first embodiment. The cell 14 has a membrane electrode assembly (MEA) 16 and a pair of separators 18 and 20 that sandwich the membrane electrode assembly 16.

[0016] The membrane electrode assembly 16 includes an electrolyte membrane 22, an anode electrode 24, and a cathode electrode 26. The electrolyte membrane 22 is sandwiched between the anode electrode 24 and the cathode electrode 26. The electrolyte membrane 22 is, for example, a solid polymer electrolyte membrane. The solid polymer electrolyte membrane is, for example, a thin film formed from a material containing a proton-conducting component that contains water. An example of the proton-conducting component is perfluorosulfonic acid.

[0017] The anode electrode 24 has an electrode catalyst layer 28 joined to the electrolyte membrane 22 and a gas diffusion layer 30 laminated on the electrode catalyst layer 28. The electrode catalyst layer 28 is formed by kneading platinum-supported carbon with a material containing a proton-conducting component to form a paste catalyst, and applying the paste catalyst to the electrolyte membrane 22 or the gas diffusion layer 30. The gas diffusion layer 30 is formed from a material containing carbon fiber.

[0018] The cathode electrode 26 has an electrode catalyst layer 32 joined to the electrolyte membrane 22 and a gas diffusion layer 34 laminated on the electrode catalyst layer 32. The electrode catalyst layer 32 is formed by kneading platinum-supported carbon with a material containing a proton-conducting component to form a paste catalyst, and applying the paste catalyst to the electrolyte membrane 22 or the gas diffusion layer 34. The gas diffusion layer 34 is formed from a material containing carbon fiber.

[0019] A flow path for the anode gas is formed on the surface of the anode-side separator 18 facing the membrane electrode assembly 16. A flow path for the cathode gas is formed on the surface of the cathode-side separator 20 facing the membrane electrode assembly 16.

[0020] [Configuration of aging device] 3 is a schematic diagram of the aging device 36 according to the first embodiment. The aging device 36 includes an aging unit 38 and an impedance measuring unit 40.

[0021] The aging unit 38 includes an anode gas supply / discharge unit 42 , a cathode gas supply / discharge unit 44 , a power supply connection circuit 46 , and a load connection circuit 48 .

[0022] The anode gas supply / discharge unit 42 includes an anode gas flow path 50 , a three-way valve 52 , a fuel gas tank 54 , an inert gas tank 56 , a humidifier 58 , and an anode off-gas flow path 60 .

[0023] The anode gas flow path 50 is connected to the fuel cell stack 10 at an anode gas inlet 62. The anode gas flow path 50 is also connected to one of a fuel gas tank 54 and an inert gas tank 56 by a three-way valve 52. The fuel gas tank 54 stores compressed hydrogen. The inert gas tank 56 stores compressed nitrogen. The three-way valve 52 allows one of the fuel gas and the inert gas to flow into the anode gas flow path 50 as the anode gas. The inert gas is, for example, nitrogen gas, but is not limited to nitrogen gas.

[0024] The anode gas that has flowed into the anode gas flow passage 50 is humidified in the humidifier 58. The moist anode gas is supplied into the fuel cell stack 10 from the anode gas inlet 62.

[0025] The anode off-gas flow path 60 is connected to the fuel cell stack 10 at an anode off-gas outlet 64. Anode gas that has not been consumed in the fuel cell stack 10 is discharged to the anode off-gas flow path 60 as anode off-gas.

[0026] The cathode gas supply / discharge unit 44 includes a cathode gas flow path 66, a three-way valve 68, a compressor 70, an inert gas tank 72, a humidifier 74, and a cathode off-gas flow path 76.

[0027] The cathode gas flow path 66 is connected to the fuel cell stack 10 at a cathode gas inlet 78. The cathode gas flow path 66 is also connected to one of a compressor 70 and an inert gas tank 72 via a three-way valve 68. The compressor 70 takes in air from the outside and sends it to the cathode gas flow path 66. The inert gas tank 72 stores compressed nitrogen. The three-way valve 68 allows one of the oxidant gas and the inert gas to flow into the cathode gas flow path 66 as the cathode gas.

[0028] The cathode gas that has flowed into the cathode gas flow passage 66 is humidified in a humidifier 74. The moist cathode gas is supplied into the fuel cell stack 10 from a cathode gas inlet 78.

[0029] The cathode offgas flow path 76 is connected to the fuel cell stack 10 at a cathode offgas outlet 80. Cathode gas that has not been consumed in the fuel cell stack 10 is discharged to the cathode offgas flow path 76 as cathode offgas.

[0030] When non-power generation aging, which will be described later, is performed on the fuel cell stack 10, the power supply connection circuit 46 connects the power supply 82 to the fuel cell stack 10. A switch 84 switches between a state in which the power supply 82 is connected to the fuel cell stack 10 and a state in which the power supply 82 is cut off from the fuel cell stack 10.

[0031] When the performance evaluation described below is performed on the fuel cell stack 10, the load connection circuit 48 connects a load 86 to the fuel cell stack 10. A switch 88 switches between a state in which the load 86 is connected to the fuel cell stack 10 and a state in which the load 86 is disconnected from the fuel cell stack 10.

[0032] The impedance measurement unit 40 measures the impedance of the cells 14 in the fuel cell stack 10. The cell 14 whose impedance is being measured may be referred to as the target cell 14a below. The target cell 14a may be one of the cells 14 in the fuel cell stack 10, or may be multiple cells 14.

[0033] 4 is a control block diagram of the aging device 36 in the first embodiment. The aging device 36 has a control unit 90.

[0034] The control unit 90 has a calculation unit 92 and a memory unit 94. The calculation unit 92 is a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). The calculation unit 92 functions as an aging control unit 96 and a proton resistance acquisition unit 98. The aging control unit 96 and the proton resistance acquisition unit 98 are realized by the calculation unit 92 executing a program stored in the memory unit 94. At least a part of the aging control unit 96 and the proton resistance acquisition unit 98 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). At least a part of the aging control unit 96 and the proton resistance acquisition unit 98 may be realized by an electronic circuit including discrete devices.

[0035] The memory unit 94 is a computer-readable, non-transitory, tangible storage medium. The memory unit 94 is composed of a volatile memory (not shown) and a non-volatile memory (not shown). The volatile memory is, for example, a random access memory (RAM). The non-volatile memory is, for example, a read-only memory (ROM), a flash memory, etc. Data, etc., are stored in the volatile memory. Programs, tables, maps, etc., are stored in the non-volatile memory. At least a portion of the memory unit 94 may be provided in the above-mentioned processor, integrated circuit, etc. At least a portion of the memory unit 94 may be mounted on a device connected to the aging device 36 via a network.

[0036] The aging control unit 96 controls the aging unit 38. The proton resistance acquisition unit 98 acquires the proton resistance of the target cell 14a based on the impedance of the target cell 14a measured by the impedance measurement unit 40.

[0037] [About aging] After assembling a fuel cell stack 10 by stacking multiple cells 14, the fuel cell stack 10 is aged to achieve the desired power generation performance. Aging the fuel cell stack 10 activates the catalyst (platinum) in the electrode catalyst layer 28 and the electrode catalyst layer 32 of each cell 14. Aging the fuel cell stack 10 also increases the water content of the electrolyte membrane 22 of each cell 14.

[0038] In the first embodiment, aging includes cyclic voltammetry aging, hydrogen pump aging, and performance evaluation. In cyclic voltammetry aging and hydrogen pump aging, fuel gas is supplied as the anode gas and an inert gas is supplied as the cathode gas, thereby bringing the fuel cell stack 10 into a non-power generation state in which power is not generated.

[0039] Hereinafter, cyclic voltammetry aging and hydrogen pump aging may be referred to as non-power generation aging. Cyclic voltammetry aging may be referred to as CV aging. Hydrogen pump aging may be referred to as HP aging.

[0040] In the first embodiment, the fuel cell stack 10 is subjected to CV aging and HP aging, and then a performance evaluation is performed on the fuel cell stack 10. In the performance evaluation, a fuel gas is supplied as the anode gas, and an oxidant gas is supplied as the cathode gas, thereby bringing the fuel cell stack 10 into a power generating state in which it generates power.

[0041] Note that even when the fuel cell stack 10 is not generating electricity, the electromotive force of the fuel cell stack 10 is not necessarily zero. However, the electromotive force of the fuel cell stack 10 when not generating electricity is sufficiently smaller than the electromotive force of the fuel cell stack 10 when generating electricity.

[0042] Cyclic voltammetry aging, hydrogen pump aging, and performance evaluation will be described in detail below.

[0043] [Cyclic voltammetry (CV) aging] In CV aging, fuel gas is supplied as the anode gas and an inert gas is supplied as the cathode gas, thereby putting the fuel cell stack 10 into a non-power generating state. In CV aging, a power source 82 is connected to the fuel cell stack 10 (FIG. 3). In CV aging, an AC voltage is applied to the fuel cell stack 10, with the anode terminal 100 of the fuel cell stack 10 serving as the negative electrode and the cathode terminal 102 serving as the positive electrode. The AC voltage applied to the fuel cell stack 10 in CV aging refers to a change in voltage, and the polarity does not change. In CV aging, the AC voltage applied to the fuel cell stack 10 is swept, for example, in the range of 0.05 V to 0.9 V. Note that the voltage applied to the fuel cell stack 10 in CV aging is not limited to an AC voltage and may be a DC voltage.

[0044] Oxides adhere to the surfaces of platinum contained in the electrode catalyst layer 28 of the anode electrode 24 and the electrode catalyst layer 32 of the cathode electrode 26 of each cell 14. As described above, by varying the voltage applied to the fuel cell stack 10, the oxides covering the surfaces of the platinum contained in the electrode catalyst layer 28 and the electrode catalyst layer 32 are removed. This increases the active surface area of ​​the platinum, and enables the electrode catalyst layer 28 and the electrode catalyst layer 32 to be activated.

[0045] The frequency at which the AC voltage applied to the fuel cell stack 10 is swept is set to 50 [Hz] to 2 [kHz].

[0046] The impedance of the cell 14 includes a resistance component and a capacitance component. When a constant voltage is applied to the fuel cell stack 10, as the voltage applied to the fuel cell stack 10 increases, the current flowing through the resistance component increases, but the current flowing through the capacitance component becomes more difficult. In other words, the amount of protons passing through the electrolyte membrane 22 decreases. The protons move with water. As the amount of protons passing through the electrolyte membrane 22 decreases, it takes time for the water content of the electrolyte membrane 22 to increase.

[0047] Furthermore, when a constant voltage is applied to the fuel cell stack 10, the charge is released from the capacitor component as the voltage applied to the fuel cell stack 10 is reduced, but it takes time for the charge to be released from the capacitor component. Therefore, the amount of protons passing through the electrolyte membrane 22 decreases, and it takes time for the water content of the electrolyte membrane 22 to increase.

[0048] In contrast, when the AC voltage applied to the fuel cell stack 10 is swept, the current flowing through the cells 14 varies in accordance with the swept AC current, allowing the capacitor components to be charged and discharged. This increases the amount of protons passing through the electrolyte membrane 22, shortening the time required for the wettability of the electrolyte membrane 22 to improve.

[0049] [About hydrogen pump (HP) aging] In HP aging, fuel gas is supplied as the anode gas and an inert gas is supplied as the cathode gas, thereby putting the fuel cell stack 10 into a non-power generating state. In HP aging, a power source 82 is connected to the fuel cell stack 10 (FIG. 3). In HP aging, a DC voltage is applied to the fuel cell stack 10, with the anode terminal 100 serving as the negative electrode and the cathode terminal 102 serving as the positive electrode. In HP aging, the DC voltage applied to the fuel cell stack 10 is maintained at, for example, 0.05 V.

[0050] When HP aging is performed on the fuel cell stack 10, the natural potential of the anode electrode 24 becomes approximately 0.1 V. This generates a potential difference between the anode electrode 24 and the cathode electrode 26 of each cell 14, causing protons to migrate from the anode electrode 24 to the cathode electrode 26. The protons migrate accompanied by water. As a result, water permeates into the electrolyte membrane 22, increasing the water content of the electrolyte membrane 22.

[0051] [Performance evaluation] In the performance evaluation, fuel gas is supplied as the anode gas and oxidant gas is supplied as the cathode gas to put the fuel cell stack 10 into a power generating state. In the performance evaluation, a load 86 is connected to the fuel cell stack 10 (FIG. 3). In the performance evaluation, it is confirmed that the voltage of the fuel cell stack 10 is equal to or higher than a predetermined voltage when the current output from the fuel cell stack 10 is a predetermined current. The predetermined current is, for example, 470 [A].

[0052] [About impedance measurement] The impedance measurement unit 40 measures the impedance of the target cell 14a by electrochemical impedance spectroscopy (hereinafter referred to as EIS). In EIS, the impedance of the target cell 14a is determined based on the AC current output when an AC voltage is applied to the target cell 14a. In the first embodiment, in EIS, an AC voltage with a frequency of 0.5 to 20 kHz and an amplitude of 10 mV is applied to the target cell 14a, but this is not limiting.

[0053] FIG. 5 is a diagram showing an equivalent circuit of the cell 14 in the first embodiment. The cell 14 is represented by resistances Rmen, Rion, and capacitance C. The resistance Rmen represents the membrane resistance of the electrolyte membrane 22. The resistance Rion represents the proton resistance of the electrode catalyst layer 32 of the cathode electrode 26. The capacitance C represents the capacitance of the electric double layer formed in the electrode catalyst layer 32 of the cathode electrode 26. Because the impedance component of the electrode catalyst layer 28 of the anode electrode 24 is sufficiently smaller than the impedance component of the electrode catalyst layer 32 of the cathode electrode 26, the element representing the impedance component of the electrode catalyst layer 28 is omitted from the equivalent circuit of FIG. 5.

[0054] Figure 6 is a Nyquist plot showing the impedance of cell 14 obtained from the equivalent circuit. Because the equivalent circuit in Figure 5 includes a capacitance C, the impedance Z of the equivalent circuit is expressed as a complex number consisting of a real component Z' and an imaginary component Z''.

[0055] If the frequency of the AC voltage applied to the cell 14 is limited to the high frequency side, the impedance Z of the equivalent circuit becomes a real number. The impedance Z at this time is derived from the resistance Rmen. That is, the resistance Rmen can be calculated from the real component Z' when the frequency of the AC voltage applied to the cell 14 is limited to the high frequency side. When calculating the impedance Z of the cell 14 using the impedance measuring unit 40, the real component Z' when the frequency of the AC voltage applied to the cell 14 is approximately 10 kHz may be used as the resistance Rmen.

[0056] As the frequency of the AC voltage applied to cell 14 is lowered, the impedance Z asymptotically approaches a straight line parallel to the imaginary axis with an intercept on the real axis of Rmen+Rion / 3. In other words, when the frequency of the AC voltage applied to cell 14 is changed by a predetermined frequency, the resistance Rmen+Rion / 3 can be calculated from the real component Z' when the change in the real component Z' becomes equal to or less than a predetermined change.

[0057] The proton resistance acquisition unit 98 can determine the resistance Rion of the target cell 14a as the proton resistance based on the change in the real component Z' when the frequency of the AC voltage applied to the target cell 14a is changed from the high frequency side to the low frequency side.

[0058] The proton resistance indicates the conductivity of protons in the electrode catalyst layer 32 of the cathode electrode 26. The higher the water content of the electrode catalyst layer 32, the higher the proton conductivity, and therefore the higher the water content of the electrode catalyst layer 32, the lower the proton resistance.

[0059] [Decrease in proton resistance due to CV aging] FIG. 7 is an image diagram of a cell 14 when CV aging is being performed on the fuel cell stack 10. As shown in FIG.

[0060] When non-power generation aging is performed on the fuel cell stack 10, in the cells 14, the difference between the proton concentration at the anode electrode 24 and the proton concentration at the cathode electrode 26 causes protons to migrate from the anode electrode 24 to the cathode electrode 26. The protons migrate accompanied by water. Hereinafter, the water that migrates with the protons may be referred to as produced water. As the produced water migrates to the cathode electrode 26 along with the protons, the water content of the electrode catalyst layer 32 of the cathode electrode 26 increases, and the proton resistance of the cells 14 decreases. When CV aging is performed on the fuel cell stack 10, protons and electrons combine in the electrode catalyst layer 32 of the cells 14 to produce hydrogen, but water is not produced.

[0061] The decrease in proton resistance of the cell 14 during CV aging includes the effect of the increase in water content in the electrode catalyst layer 32 due to produced water, but does not include the effect of the increase in water content in the electrode catalyst layer 32 due to water production.

[0062] [Decrease in proton resistance due to performance evaluation] FIG. 8 is an image diagram of the cell 14 when the performance of the fuel cell stack 10 is being evaluated.

[0063] When performance evaluation is performed on the fuel cell stack 10, in the cell 14, the difference between the proton concentration at the anode electrode 24 and the proton concentration at the cathode electrode 26 causes protons to move from the anode electrode 24 to the cathode electrode 26. As the protons move with the produced water to the cathode electrode 26, the water content of the electrode catalyst layer 32 of the cathode electrode 26 increases, and the proton resistance of the cell 14 decreases.

[0064] When performance evaluation is performed on the fuel cell stack 10, protons, oxygen, and electrons combine to generate water in the electrode catalyst layer 32 of the cathode electrode 26 of the cell 14. Hereinafter, the water generated in the electrode catalyst layer 32 may be referred to as generated water. The generated water increases the water content of the electrode catalyst layer 32, and the proton resistance of the cell 14 decreases.

[0065] That is, the decrease in proton resistance of the cell 14 in the performance evaluation includes the effect of the increase in water content of the electrode catalyst layer 32 due to produced water and the effect of the increase in water content of the electrode catalyst layer 32 due to produced water.

[0066] [About proton resistance] In the first embodiment, the proton resistance acquisition unit 98 acquires the proton resistance of the target cell 14a during CV aging. The proton resistance acquisition unit 98 also acquires the proton resistance of the target cell 14a after performance evaluation. In the first embodiment, the proton resistance of the target cell 14a acquired during CV aging may be referred to as a first proton resistance. The proton resistance of the target cell 14a acquired after performance evaluation may be referred to as a second proton resistance.

[0067] In the first embodiment, the proton resistance acquisition unit 98 acquires, as the third proton resistance of the target cell 14a, a value obtained by subtracting the second proton resistance of the target cell 14a from the first proton resistance of the target cell 14a.

[0068] Fig. 9 is a time chart showing the change in proton resistance of the target cell 14a due to aging of the fuel cell stack 10. In the first embodiment, CV aging, HP aging, and performance evaluation are performed in this order on the fuel cell stack 10. Fig. 9 shows an image of the change in proton resistance of the target cell 14a when CV aging, HP aging, and performance evaluation are performed.

[0069] R1 in Figure 9 indicates the first proton resistance of the target cell 14a. The first proton resistance of the target cell 14a is obtained during CV aging. R2 in Figure 9 indicates the second proton resistance of the target cell 14a. The second proton resistance of the target cell 14a is obtained after performance evaluation. R3 in Figure 9 indicates the third proton resistance of the target cell 14a. The difference between the first proton resistance of the target cell 14a and the second proton resistance of the target cell 14a is obtained as the third proton resistance of the target cell 14a. The number in parentheses indicates the number of times aging has been performed on the fuel cell stack 10.

[0070] As the fuel cell stack 10 is repeatedly subjected to aging, the water content of the electrode catalyst layer 32 of the cathode electrode 26 of the target cell 14a becomes saturated. Therefore, the more times the fuel cell stack 10 is aged, the smaller the decrease in proton resistance of the target cell 14a due to aging becomes.

[0071] Therefore, the degree of aging can be determined from the third proton resistance of the target cell 14a. In the first embodiment, when the third proton resistance of the target cell 14a becomes equal to or less than a predetermined resistance value, aging of the fuel cell stack 10 is terminated.

[0072] [Regarding the timing of obtaining the first proton resistance] FIG. 10 shows a cyclic voltammogram. The potential difference between the cathode electrode 26 and the anode electrode 24 of the cell 14 was swept from 0.05 V to 0.9 V, and then from 0.9 V to 0.05 V. This cycle was repeated 2,000 times. The cyclic voltammogram in FIG. 10 shows the change in the output current of the cell 14 in the first cycle, the change in the output current of the cell 14 in the 1,000th cycle, and the change in the output current of the cell 14 in the 2,000th cycle. The cyclic voltammogram in FIG. 10 shows that at 0.45 V, the change in the output current of the cell 14 with respect to the number of cycles is small.

[0073] Therefore, in the first embodiment, when acquiring the first proton resistance, the proton resistance acquiring unit 98 acquires the first proton resistance of the target cell 14a based on the output current of the target cell 14a when the AC voltage applied to the fuel cell stack 10 is 0.45 [V] (predetermined voltage) during CV aging. This allows the proton resistance acquiring unit 98 to acquire a first proton resistance that varies little depending on the number of sweep cycles during CV aging. The timing for acquiring the first proton resistance is not limited to when the AC voltage applied to the fuel cell stack 10 is 0.45 [V], but may be when the AC voltage is in the range of 0.1 [V] to 0.45 [V].

[0074] [Aging treatment] 11 is a flowchart of the aging process executed by the control unit 90 in the first embodiment. The aging process is executed when aging is performed on the fuel cell stack 10.

[0075] In step S1, the aging control unit 96 performs CV aging on the fuel cell stack 10 for a predetermined time. When performing CV aging on the fuel cell stack 10, the aging control unit 96 supplies fuel gas as the anode gas and inert gas as the cathode gas to the fuel cell stack 10. The proton resistance acquisition unit 98 acquires the first proton resistance of the target cell 14a during CV aging. After CV aging has been performed on the fuel cell stack 10 for a predetermined time, the process proceeds to step S2.

[0076] In step S2, the aging control unit 96 performs HP aging for a predetermined time on the fuel cell stack 10. When performing HP aging on the fuel cell stack 10, the aging control unit 96 supplies fuel gas as the anode gas and inert gas as the cathode gas to the fuel cell stack 10. After HP aging has been performed on the fuel cell stack 10 for the predetermined time, the process proceeds to step S3.

[0077] In step S3, the aging control unit 96 performs a performance evaluation on the fuel cell stack 10. When performing a performance evaluation on the fuel cell stack 10, the aging control unit 96 supplies a fuel gas as an anode gas and an oxidant gas as a cathode gas to the fuel cell stack 10. After the performance evaluation on the fuel cell stack 10 has been performed, the process proceeds to step S4.

[0078] In step S4, the aging control unit 96 puts the fuel cell stack 10 into a power generation stopped state. When putting the fuel cell stack 10 into a power generation stopped state, the aging control unit 96 supplies fuel gas as the anode gas and inert gas as the cathode gas to the fuel cell stack 10. After putting the fuel cell stack 10 into a power generation stopped state, the process proceeds to step S5.

[0079] In step S5, the proton resistance acquisition unit 98 acquires the second proton resistance of the target cell 14a, and then the process proceeds to step S6.

[0080] In step S6, the aging control unit 96 purges the fuel cell stack 10. When purging the fuel cell stack 10, the aging control unit 96 supplies an inert gas as the anode gas and an inert gas as the cathode gas to the fuel cell stack 10. After purging the fuel cell stack 10, the process proceeds to step S7.

[0081] In step S7, the proton resistance acquisition unit 98 acquires the difference between the first proton resistance of the target cell 14a and the second proton resistance of the target cell 14a as the third proton resistance of the target cell 14a, and then proceeds to step S8.

[0082] In step S8, the aging control unit 96 determines whether the third proton resistance of the target cell 14a is equal to or less than a predetermined resistance value. If the third proton resistance of the target cell 14a is equal to or less than the predetermined resistance value, the aging process ends. If the third proton resistance of the target cell 14a is greater than the predetermined resistance value, the process returns to step S1.

[0083] Second Embodiment In the aging device 36 of the first embodiment, the proton resistance acquisition unit 98 acquired the difference between the first proton resistance of the target cell 14a acquired during CV aging and the second proton resistance of the target cell 14a acquired after performance evaluation as the third proton resistance of the target cell 14a.

[0084] In contrast, in the aging device 36 of the second embodiment, the proton resistance acquisition unit 98 acquires the difference between the first proton resistance of the target cell 14a acquired during HP aging and the second proton resistance of the target cell 14a acquired after performance evaluation as the third proton resistance of the target cell 14a.

[0085] The aging device 36 of the second embodiment will be described below, but a description of the same configuration as the aging device 36 of the first embodiment will be omitted.

[0086] [About proton resistance] In the second embodiment, the proton resistance acquisition unit 98 acquires the proton resistance of the target cell 14a during HP aging. Also, the proton resistance acquisition unit 98 acquires the proton resistance of the target cell 14a after performance evaluation. In the second embodiment, the proton resistance of the target cell 14a acquired during HP aging may be referred to as a first proton resistance. Also, the proton resistance of the target cell 14a acquired after performance evaluation may be referred to as a second proton resistance.

[0087] In the second embodiment, the proton resistance acquisition unit 98 acquires the difference between the first proton resistance of the target cell 14a and the second proton resistance of the target cell 14a as the third proton resistance of the target cell 14a.

[0088] Fig. 12 is a time chart showing the change in proton resistance of the cell 14 due to aging of the fuel cell stack 10. In the second embodiment, CV aging, HP aging, and performance evaluation are sequentially performed on the fuel cell stack 10. Fig. 12 shows an image of the change in proton resistance of the target cell 14a when CV aging, HP aging, and performance evaluation are performed.

[0089] R1 in FIG. 12 indicates the first proton resistance of the target cell 14a. The first proton resistance of the target cell 14a is obtained during HP aging. R2 in FIG. 12 indicates the second proton resistance of the target cell 14a. The second proton resistance of the target cell 14a is obtained after performance evaluation. R3 in FIG. 12 indicates the third proton resistance of the target cell 14a. The difference between the first proton resistance of the target cell 14a and the second proton resistance of the target cell 14a is obtained as the third proton resistance of the target cell 14a. The number in parentheses indicates the number of times aging has been performed on the fuel cell stack 10.

[0090] As the fuel cell stack 10 is repeatedly subjected to aging, the water content of the electrode catalyst layer 32 of the cathode electrode 26 of the target cell 14a becomes saturated. Therefore, the more times the fuel cell stack 10 is aged, the smaller the decrease in proton resistance of the target cell 14a due to aging becomes.

[0091] Therefore, the degree of aging can be determined from the third proton resistance of the target cell 14a. In the second embodiment, when the third proton resistance of the target cell 14a becomes equal to or less than a predetermined resistance value, aging of the fuel cell stack 10 is terminated.

[0092] [Aging treatment] 13 is a flowchart of the aging process executed by the control unit 90 in the second embodiment. The aging process is executed when aging is performed on the fuel cell stack 10.

[0093] In step S11, the aging control unit 96 performs CV aging for a predetermined time on the fuel cell stack 10. When performing CV aging on the fuel cell stack 10, the aging control unit 96 supplies fuel gas as the anode gas and inert gas as the cathode gas to the fuel cell stack 10. After CV aging has been performed on the fuel cell stack 10 for the predetermined time, the process proceeds to step S12.

[0094] In step S12, the aging control unit 96 performs HP aging on the fuel cell stack 10 for a predetermined time. When performing HP aging on the fuel cell stack 10, the aging control unit 96 supplies fuel gas as the anode gas and inert gas as the cathode gas to the fuel cell stack 10. The proton resistance acquisition unit 98 acquires the first proton resistance of the target cell 14a during HP aging. After HP aging has been performed on the fuel cell stack 10 for the predetermined time, the process proceeds to step S13.

[0095] In step S13, the aging control unit 96 performs a performance evaluation on the fuel cell stack 10. When performing a performance evaluation on the fuel cell stack 10, the aging control unit 96 supplies a fuel gas as an anode gas and an oxidant gas as a cathode gas to the fuel cell stack 10. After the performance evaluation on the fuel cell stack 10 has been performed, the process proceeds to step S14.

[0096] In step S14, the aging control unit 96 puts the fuel cell stack 10 into a power generation stopped state. When putting the fuel cell stack 10 into a power generation stopped state, the aging control unit 96 supplies fuel gas as the anode gas and inert gas as the cathode gas to the fuel cell stack 10. After putting the fuel cell stack 10 into a power generation stopped state, the process proceeds to step S15.

[0097] In step S15, the proton resistance acquisition unit 98 acquires the second proton resistance of the target cell 14a, and then the process proceeds to step S16.

[0098] In step S16, the aging control unit 96 purges the fuel cell stack 10. When purging the fuel cell stack 10, the aging control unit 96 supplies an inert gas as the anode gas and an inert gas as the cathode gas to the fuel cell stack 10. After purging the fuel cell stack 10, the process proceeds to step S17.

[0099] In step S17, the proton resistance acquisition unit 98 acquires the difference between the first proton resistance of the target cell 14a and the second proton resistance of the target cell 14a as the third proton resistance of the target cell 14a, and then proceeds to step S18.

[0100] In step S18, the aging control unit 96 determines whether the third proton resistance of the target cell 14a is equal to or less than a predetermined resistance value. If the third proton resistance of the target cell 14a is equal to or less than the predetermined resistance value, the aging process ends. If the third proton resistance of the target cell 14a is greater than the predetermined resistance value, the process returns to step S11. The predetermined resistance value may be the same as or different from the predetermined resistance value in step 8 of the aging process of the first embodiment.

[0101] Third Embodiment The aging device 36 of the first embodiment determines the end point of aging for the fuel cell stack 10 based on the third proton resistance of the target cell 14a. In contrast, the aging device 36 of the third embodiment determines the end point of aging for the fuel cell stack 10 based on the amount of water produced in the target cell 14a.

[0102] The aging device 36 of the second embodiment will be described below, but a description of the same configuration as the aging device 36 of the first embodiment will be omitted.

[0103] [Configuration of aging device] 14 is a control block diagram of the aging device 36 in the third embodiment. The aging device 36 has a control unit 90.

[0104] The control unit 90 has a calculation unit 92 and a memory unit 94. The calculation unit 92 is a processor such as a CPU or GPU. The calculation unit 92 functions as an aging control unit 96, a proton resistance acquisition unit 98, and a produced water volume acquisition unit 104. The aging control unit 96, the proton resistance acquisition unit 98, and the produced water volume acquisition unit 104 are realized by the calculation unit 92 executing a program stored in the memory unit 94. At least a portion of the aging control unit 96, the proton resistance acquisition unit 98, and the produced water volume acquisition unit 104 may be realized by an integrated circuit such as an ASIC or an FPGA. At least a portion of the aging control unit 96, the proton resistance acquisition unit 98, and the produced water volume acquisition unit 104 may be realized by an electronic circuit including discrete devices.

[0105] The memory unit 94 is a computer-readable, non-transitory, tangible storage medium. The memory unit 94 is composed of a volatile memory (not shown) and a non-volatile memory (not shown). The volatile memory is, for example, a RAM. The non-volatile memory is, for example, a ROM, a flash memory, etc. Data, etc. are stored in the volatile memory, for example. Programs, tables, maps, etc. are stored in the non-volatile memory, for example. At least a portion of the memory unit 94 may be provided in the above-mentioned processor, integrated circuit, etc. At least a portion of the memory unit 94 may be installed in a device connected to the aging device 36 via a network.

[0106] The aging control unit 96 controls the aging unit 38. The proton resistance acquisition unit 98 acquires the proton resistance of the target cell 14a based on the impedance of the target cell 14a measured by the impedance measurement unit 40. As in the first embodiment, the proton resistance acquisition unit 98 acquires the first proton resistance of the target cell 14a during CV aging and acquires the second proton resistance of the target cell 14a after performance evaluation. The proton resistance acquisition unit 98 acquires the difference between the first proton resistance of the target cell 14a and the second proton resistance of the target cell 14a as the third proton resistance. The produced water amount acquisition unit 104 acquires the produced water amount of the target cell 14a based on the third proton resistance of the target cell 14a.

[0107] [Amount of water produced by the cell] The proton resistance of the cell 14 indicates the ionic conductivity in the electrode catalyst layer 28 of the anode electrode 24 and the electrode catalyst layer 32 of the cathode electrode 26. When the amount of water produced in the cell 14 is small, the movement of protons is particularly inhibited in the electrode catalyst layer 32 of the cell 14, and the proton resistance increases. Therefore, the proton resistance of the cell 14 has a high correlation with the amount of water produced in the cell 14, and the amount of water produced in the cell 14 can be determined from the proton resistance of the cell 14.

[0108] The greater the water content in the electrode catalyst layer 32 of the cell 14, the lower the proton resistance of the cell 14. When the fuel cell stack 10 is put into a power generating state, water is produced in the cell 14, and the water content of the electrode catalyst layer 32 of the cell 14 increases due to the produced water and accompanying water. Therefore, the proton resistance of the cell 14 after the fuel cell stack 10 is put into a power generating state is smaller than the proton resistance of the cell 14 before the fuel cell stack 10 is put into a power generating state.

[0109] However, the decrease in proton resistance of the cells 14 after the fuel cell stack 10 is put into a power generating state includes the effect of the decrease in proton resistance caused by the increase in water content in the electrode catalyst layer 32 due to produced water, and the effect of the decrease in proton resistance caused by the increase in water content in the electrode catalyst layer 32 due to produced water. Therefore, if the amount of water produced in the cells 14 is calculated from the proton resistance of the cells 14 after the fuel cell stack 10 is put into a power generating state, the calculated amount of water produced will be less accurate.

[0110] When the fuel cell stack 10 is in a non-power-generating state, no water is produced, and therefore the water content of the electrode catalyst layer 32 of the cell 14 increases due to produced water, but the water content of the electrode catalyst layer 32 of the cell 14 does not increase due to produced water. Therefore, the decrease in proton resistance of the cell 14 after the fuel cell stack 10 is in a non-power-generating state does not include the effect of the decrease in proton resistance that accompanies the increase in water content of the electrode catalyst layer 32 due to produced water.

[0111] In the third embodiment, the produced water amount acquisition unit 104 acquires the amount of produced water in the target cell 14a based on the third proton resistance of the target cell 14a. The third proton resistance of the target cell 14a is a value obtained by subtracting the second proton resistance of the target cell 14a, which was acquired after performance evaluation, from the first proton resistance of the target cell 14a, which was acquired during CV aging. Therefore, it can be said that the third proton resistance of the target cell 14a indicates a decrease in the proton resistance of the target cell 14a due to an increase in the water content of the electrode catalyst layer 32 caused by produced water.

[0112] Fig. 15 is a map for determining the amount of water produced in the cell 14 from the proton resistance of the cell 14 in the third embodiment. The map in Fig. 15 is determined in advance by experiment or the like.

[0113] For example, when the third proton resistance of the target cell 14a is Ra [Ω·cm^2], the amount of water produced in the target cell 14a can be determined as Aa [L] from the map of FIG.

[0114] Fig. 16 is a time chart showing the change in the amount of water produced due to aging in the third embodiment. In the third embodiment, CV aging, HP aging, and performance evaluation are sequentially performed on the fuel cell stack 10. Fig. 16 shows an image of the change in the water content of the electrode catalyst layer 32 in the cathode electrode 26 of the target cell 14a when CV aging, HP aging, and performance evaluation are performed.

[0115] M1 in FIG. 16 indicates the water content of the electrode catalyst layer 32 of the target cell 14a after CV aging. M2 in FIG. 16 indicates the water content of the electrode catalyst layer 32 of the target cell 14a after performance evaluation. ΔM indicates the difference between the water content of the electrode catalyst layer 32 of the target cell 14a after performance evaluation and the water content of the electrode catalyst layer 32 of the target cell 14a after CV aging. ΔM can be considered to be the amount of water generated in the target cell 14a between after CV aging and after performance evaluation. The number in parentheses indicates the number of times aging has been performed on the fuel cell stack 10.

[0116] As aging is repeatedly performed on the fuel cell stack 10, the water content in the electrode catalyst layer 32 of the cathode electrode 26 of the target cell 14a becomes saturated, and the amount of water produced in the target cell 14a also decreases. Therefore, the progress of aging can be determined from the difference ΔM between the water content in the electrode catalyst layer 32 of the target cell 14a after performance evaluation and the water content in the electrode catalyst layer 32 of the target cell 14a after CV aging. In the third embodiment, aging of the fuel cell stack 10 is terminated when the difference ΔM between the water content in the electrode catalyst layer 32 of the target cell 14a after performance evaluation and the water content in the electrode catalyst layer 32 of the target cell 14a after CV aging becomes equal to or less than a predetermined water amount.

[0117] [Aging treatment] 17 is a flowchart of the aging process executed by the control unit 90 in the third embodiment. The aging process is executed when aging is performed on the fuel cell stack 10.

[0118] In step S21, the aging control unit 96 performs CV aging on the fuel cell stack 10 for a predetermined time. When performing CV aging on the fuel cell stack 10, the aging control unit 96 supplies fuel gas as the anode gas and inert gas as the cathode gas to the fuel cell stack 10. The proton resistance acquisition unit 98 acquires the first proton resistance of the target cell 14a during CV aging. After CV aging has been performed on the fuel cell stack 10 for the predetermined time, the process proceeds to step S22.

[0119] In step S22, the aging control unit 96 performs HP aging for a predetermined time on the fuel cell stack 10. When performing HP aging on the fuel cell stack 10, the aging control unit 96 supplies fuel gas as the anode gas and inert gas as the cathode gas to the fuel cell stack 10. After HP aging has been performed on the fuel cell stack 10 for the predetermined time, the process proceeds to step S23.

[0120] In step S23, the aging control unit 96 performs a performance evaluation on the fuel cell stack 10. When performing a performance evaluation on the fuel cell stack 10, the aging control unit 96 supplies a fuel gas as an anode gas and an oxidant gas as a cathode gas to the fuel cell stack 10. After the performance evaluation on the fuel cell stack 10 has been performed, the process proceeds to step S24.

[0121] In step S24, the aging control unit 96 puts the fuel cell stack 10 into a power generation stopped state. When putting the fuel cell stack 10 into a power generation stopped state, the aging control unit 96 supplies fuel gas as the anode gas and inert gas as the cathode gas to the fuel cell stack 10. After putting the fuel cell stack 10 into a power generation stopped state, the process proceeds to step S25.

[0122] In step S25, the proton resistance acquisition unit 98 acquires the second proton resistance of the target cell 14a, and then the process proceeds to step S26.

[0123] In step S26, the aging control unit 96 purges the fuel cell stack 10. When purging the fuel cell stack 10, the aging control unit 96 supplies an inert gas as the anode gas and an inert gas as the cathode gas to the fuel cell stack 10. After purging the fuel cell stack 10, the process proceeds to step S27.

[0124] In step S27, the proton resistance acquisition unit 98 acquires the difference between the first proton resistance of the target cell 14a and the second proton resistance of the target cell 14a as the third proton resistance of the target cell 14a, and then proceeds to step S28.

[0125] In step S28, the produced water amount acquisition unit 104 acquires the produced water amount in the target cell 14a based on the third proton resistance of the target cell 14a and the map in Fig. 15. Then, the process proceeds to step S29.

[0126] In step S29, the aging control unit 96 determines whether the amount of water produced in the target cell 14a is equal to or less than a predetermined amount. If the amount of water produced in the target cell 14a is equal to or less than the predetermined amount, the aging process ends. If the amount of water produced in the target cell 14a is greater than the predetermined amount, the process returns to step S21.

[0127] In the above, the proton resistance acquisition unit 98 acquires the proton resistance of the target cell 14a during CV aging as the first proton resistance of the target cell 14a. Alternatively, the proton resistance acquisition unit 98 may acquire the proton resistance of the target cell 14a during HP aging as the first proton resistance of the target cell 14a, as in the second embodiment.

[0128] [Fourth embodiment] In the aging device 36 of the first embodiment, CV aging, HP aging, and performance evaluation are performed as one set on the fuel cell stack 10, and this set of aging is repeatedly performed on the fuel cell stack 10. In contrast, in the aging device 36 of the fourth embodiment, CV aging and HP aging are repeatedly performed on the fuel cell stack 10, and then performance evaluation is repeatedly performed on the fuel cell stack 10.

[0129] The aging device 36 of the fourth embodiment will be described below, but a description of the same configuration as the aging device 36 of the first embodiment will be omitted.

[0130] [Aging treatment] 18 is a flowchart of the aging process in the fourth embodiment. The aging process is carried out when aging is performed on the fuel cell stack 10.

[0131] In step S31, the aging control unit 96 performs CV aging on the fuel cell stack 10 for a predetermined time. When performing CV aging on the fuel cell stack 10, the aging control unit 96 supplies fuel gas as the anode gas and inert gas as the cathode gas to the fuel cell stack 10. The proton resistance acquisition unit 98 acquires the first proton resistance of the target cell 14a during CV aging. After CV aging has been performed on the fuel cell stack 10 for the predetermined time, the process proceeds to step S32.

[0132] In step S32, the aging control unit 96 performs HP aging for a predetermined time on the fuel cell stack 10. When performing HP aging on the fuel cell stack 10, the aging control unit 96 supplies fuel gas as the anode gas and inert gas as the cathode gas to the fuel cell stack 10. After HP aging has been performed on the fuel cell stack 10 for the predetermined time, the process proceeds to step S33.

[0133] In step S33, the aging control unit 96 determines whether the value obtained by subtracting the current value from the previous value of the first proton resistance of the target cell 14a is equal to or less than a predetermined value. If the value obtained by subtracting the current value from the previous value of the first proton resistance of the target cell 14a is equal to or less than the predetermined value, the process proceeds to step S34. If the value obtained by subtracting the current value from the previous value of the first proton resistance of the target cell 14a is greater than the predetermined value, the process returns to step S31.

[0134] In step S34, the aging control unit 96 performs a performance evaluation on the fuel cell stack 10. When performing a performance evaluation on the fuel cell stack 10, the aging control unit 96 supplies a fuel gas as an anode gas and an oxidant gas as a cathode gas to the fuel cell stack 10. After the performance evaluation on the fuel cell stack 10 has been performed, the process proceeds to step S35.

[0135] In step S35, the aging control unit 96 puts the fuel cell stack 10 into a power generation stopped state. When putting the fuel cell stack 10 into a power generation stopped state, the aging control unit 96 supplies fuel gas as the anode gas and inert gas as the cathode gas to the fuel cell stack 10. After putting the fuel cell stack 10 into a power generation stopped state, the process proceeds to step S36.

[0136] In step S36, the proton resistance acquisition unit 98 acquires the second proton resistance of the target cell 14a, and then the process proceeds to step S37.

[0137] In step S37, the aging control unit 96 purges the fuel cell stack 10. When purging the fuel cell stack 10, the aging control unit 96 supplies an inert gas as the anode gas and an inert gas as the cathode gas to the fuel cell stack 10. After purging the fuel cell stack 10, the process proceeds to step S38.

[0138] In step S38, the proton resistance acquisition unit 98 acquires the difference between the last acquired first proton resistance of the target cell 14a and the current value of the second proton resistance of the target cell 14a as the third proton resistance of the target cell 14a. Then, the process proceeds to step S39.

[0139] In step S39, the aging control unit 96 determines whether the third proton resistance of the target cell 14a is equal to or less than a predetermined resistance value. If the third proton resistance of the target cell 14a is equal to or less than the predetermined resistance value, the aging process ends. If the third proton resistance of the target cell 14a is greater than the predetermined resistance value, the process returns to step S34.

[0140] In the fourth embodiment, CV aging and HP aging are repeatedly performed on the fuel cell stack 10, in which an inert gas is supplied to the fuel cell stack 10 as the cathode gas. Thereafter, performance evaluation is repeatedly performed on the fuel cell, in which an oxidant gas is supplied to the fuel cell stack 10 as the cathode gas. This reduces the frequency of switching the cathode gas, thereby reducing fuel gas consumption.

[0141] In the above, the proton resistance acquisition unit 98 acquires the proton resistance of the target cell 14a during CV aging as the first proton resistance of the target cell 14a. Alternatively, the proton resistance acquisition unit 98 may acquire the proton resistance of the target cell 14a during HP aging as the first proton resistance of the target cell 14a, as in the second embodiment.

[0142] 19 is a time chart showing the change in proton resistance due to aging in the fourth embodiment. In the fourth embodiment, the fuel cell stack 10 is repeatedly subjected to CV aging and HP aging, and then the performance evaluation is repeatedly performed on the fuel cell stack 10.

[0143] R1 in FIG. 19 indicates the first proton resistance of the target cell 14a. The first proton resistance of the target cell 14a is obtained during CV aging. R2 in FIG. 19 indicates the second proton resistance of the target cell 14a. The second proton resistance of the target cell 14a is obtained after performance evaluation. ΔR1 in FIG. 19 indicates the difference between the previous value of the first proton resistance of the target cell 14a and the current value of the first proton resistance of the target cell 14a. R3 in FIG. 19 indicates the third proton resistance of the target cell 14a. The difference between the last obtained first proton resistance of the target cell 14a and the current value of the second proton resistance of the target cell 14a is obtained as the third proton resistance of the target cell 14a. The numbers in parentheses indicate the number of times CV aging has been performed on the fuel cell stack 10 or the number of times performance evaluation has been performed on the fuel cell stack 10.

[0144] By repeatedly performing CV aging and HP aging on the fuel cell stack 10, the water content of the electrode catalyst layer 32 of the cathode electrode 26 of the target cell 14a becomes saturated. Therefore, the more times the fuel cell stack 10 is subjected to CV aging and HP aging, the smaller the degree of decrease in proton resistance of the target cell 14a due to CV aging and HP aging becomes.

[0145] The degree of aging progress can be determined from the difference between the previous value of the first proton resistance of the target cell 14a and the current value of the first proton resistance of the target cell 14a. In the fourth embodiment, when the difference between the previous value of the first proton resistance of the target cell 14a and the current value of the first proton resistance of the target cell 14a becomes equal to or less than a predetermined value, CV aging and HP aging for the fuel cell stack 10 are terminated.

[0146] By performing CV aging and HP aging on the fuel cell stack 10, the water content of the electrode catalyst layer 32 of the cathode electrode 26 of the target cell 14a can be increased by produced water. Furthermore, by performing a performance evaluation on the fuel cell stack 10, the water content of the electrode catalyst layer 32 of the cathode electrode 26 of the target cell 14a can be increased by produced water.

[0147] As the performance evaluation of the fuel cell stack 10 is repeatedly performed, the water content of the electrode catalyst layer 32 of the cathode electrode 26 of the target cell 14a becomes saturated. Therefore, the more times the performance evaluation of the fuel cell stack 10 is performed, the smaller the degree of decrease in the proton resistance of the target cell 14a due to the performance evaluation becomes.

[0148] Therefore, the degree of aging can be determined from the third proton resistance of the target cell 14a. In the fourth embodiment, when the third proton resistance of the target cell 14a becomes equal to or less than a predetermined resistance value, aging of the fuel cell stack 10 is terminated.

[0149] According to the above embodiment, the end time of aging can be set based on the impedance of each cell, which in turn contributes to energy efficiency.

[0150] The following additional notes are further disclosed regarding the above embodiment.

[0151] (Appendix 1) The aging device (36) of the present disclosure is an aging device for aging a fuel cell stack (10) having a plurality of cells (14), and includes an aging unit (38) that supplies an anode gas and a cathode gas to the fuel cell stack to perform the aging, and a proton resistance acquisition unit (98) that acquires the proton resistance of a target cell (14a) that is at least one of the cells of the fuel cell stack, wherein the aging unit performs a non-power generation process, which is aging of the fuel cell stack in a non-power generation state in which the fuel cell stack is not generating power, by supplying hydrogen gas as the anode gas and an inert gas as the cathode gas, and a non-power generation process, which is aging of the fuel cell stack in a non-power generation state in which the fuel cell stack is not generating power, by supplying the hydrogen gas as the anode gas and an oxygen-containing gas as the cathode gas after the non-power generation process. The proton resistance acquisition unit is capable of executing a power generation process that causes the fuel cell stack to generate power by supplying an inert gas as the cathode gas, and a power generation stop process that places the fuel cell stack in a power generation stopped state after the power generation process by supplying the inert gas as the cathode gas, and the proton resistance acquisition unit is capable of executing a first proton resistance acquisition process that acquires, as a first proton resistance, the proton resistance of the target cell when the non-power generation aging is being performed on the fuel cell stack, a second proton resistance acquisition process that acquires, as a second proton resistance, the proton resistance of the target cell when the fuel cell stack is in the power generation stopped state, and a third proton resistance acquisition process that acquires a third proton resistance that is a value corresponding to the difference between the first proton resistance of the target cell and the second proton resistance of the target cell. This allows the third proton resistance to be acquired based on the first proton resistance of the target cell acquired when non-power generation aging is being performed and the second proton resistance of the target cell acquired when the fuel cell is in the power generation stopped state.

[0152] (Appendix 2) In the aging device described in Supplementary Note 1, the aging unit may repeatedly perform the non-power generation process at least until the third proton resistance of the target cell becomes equal to or less than a predetermined resistance value. This allows the end point of aging for the fuel cell stack to be determined based on the third proton resistance of the target cell.

[0153] (Appendix 3) The aging device according to Supplementary Note 1 may further include a generated water amount acquisition unit (104) that acquires, based on the third proton resistance of the target cell, the amount of water generated in the target cell when the fuel cell stack is generating electricity, and the aging unit may repeatedly execute the non-power generation process at least until the amount of water generated reaches a predetermined amount. This allows the end point of aging for the fuel cell stack to be determined based on the amount of water generated in the target cell.

[0154] (Appendix 4) In the aging device described in Supplementary Note 1, the aging unit performs at least cyclic voltammetry aging as the non-power generation aging, in which a voltage applied to the fuel cell stack is repeatedly swept, and when the aging unit performs cyclic voltammetry aging as the non-power generation aging, the frequency of the sweep of the AC voltage applied to the fuel cell stack may be set to a predetermined range of frequencies, thereby shortening the time for cyclic voltammetry aging.

[0155] (Appendix 5) In the aging device described in Supplementary Note 1, the aging unit may perform at least cyclic voltammetry aging as the non-power generation aging, in which a voltage applied to the fuel cell stack is repeatedly swept, and when the aging unit performs cyclic voltammetry aging as the non-power generation aging, the proton resistance acquisition unit may acquire the first proton resistance of the target cell when the voltage applied to the fuel cell stack is a predetermined voltage. This makes it possible to accurately acquire the first proton resistance.

[0156] (Appendix 6) The aging method of the present disclosure is an aging method for aging a fuel cell stack having a plurality of cells, and includes a non-power generation step of performing non-power generation aging on the fuel cell stack in a non-power generation state in which the fuel cell stack is not generating power by supplying hydrogen gas as an anode gas and an inert gas as a cathode gas; a first proton resistance acquisition step of acquiring, as a first proton resistance, the proton resistance of a target cell that is at least one of the cells of the fuel cell stack while the non-power generation aging is being performed on the fuel cell stack; and after the first proton resistance acquisition step, The fuel cell stack includes a power generation step of generating electricity by supplying the hydrogen gas as the anode gas and an oxygen-containing gas as the cathode gas, a power generation stopping step of putting the fuel cell stack into a power generation stopped state by supplying the inert gas as the cathode gas after the power generation step, a second proton resistance acquisition step of acquiring the proton resistance of the target cell when the fuel cell stack is in the power generation stopped state as a second proton resistance, and a third proton resistance acquisition unit that acquires a third proton resistance that is a value corresponding to the difference between the first proton resistance of the target cell and the second proton resistance of the target cell. This makes it possible to acquire the third proton resistance based on the first proton resistance of the target cell acquired when non-power generation aging is being performed and the second proton resistance of the target cell acquired when the fuel cell is in the power generation stopped state.

[0157] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments. [Explanation of symbols]

[0158] 10...Fuel cell stack 14...Cell 14a...Target cell 22...Electrolyte membrane 24...Anode electrode 26...Cathode electrode 36...Aging device 38...Aging section 98... Proton resistance acquisition unit 104... Generated water amount acquisition unit

Claims

1. An aging device for aging a fuel cell stack having a plurality of cells, an aging unit that supplies an anode gas and a cathode gas to the fuel cell stack to perform the aging process; a proton resistance acquisition unit that acquires a proton resistance of a target cell, which is at least one of the cells of the fuel cell stack; and The aging section includes: a non-power generation process in which hydrogen gas is supplied as the anode gas and an inert gas is supplied as the cathode gas, thereby performing non-power generation aging on the fuel cell stack in a non-power generation state in which the fuel cell stack is not generating power; a power generation process in which, after the non-power generation process, the hydrogen gas is supplied as the anode gas and an oxygen-containing gas is supplied as the cathode gas, thereby causing the fuel cell stack to generate power; a power generation stopping process for stopping the power generation of the fuel cell stack by supplying the inert gas as the cathode gas after the power generation process; is executable, The proton resistance acquisition unit a first proton resistance acquisition process for acquiring, as a first proton resistance, the proton resistance of the target cell when the non-power generation aging is being performed on the fuel cell stack; a second proton resistance acquisition process for acquiring, as a second proton resistance, the proton resistance of the target cell when the fuel cell stack is in the power generation stopped state; a third proton resistance acquisition process for acquiring a third proton resistance that is a value corresponding to a difference between the first proton resistance of the target cell and the second proton resistance of the target cell; An aging device capable of performing the above.

2. 2. The aging device according to claim 1, The aging unit repeatedly performs at least the non-power generation process until the third proton resistance of the target cell becomes equal to or less than a predetermined resistance value.

3. 2. The aging device according to claim 1, a generated water amount acquiring unit that acquires a generated water amount, which is the amount of water generated in the target cell when power is generated by the fuel cell stack, based on the third proton resistance of the target cell; The aging unit repeatedly performs at least the non-power generation process until the amount of generated water reaches a predetermined amount of water.

4. 2. The aging device according to claim 1, the aging unit performs at least cyclic voltammetry aging, as the non-power generation aging, in which a voltage applied to the fuel cell stack is repeatedly swept; An aging device, wherein when the aging unit performs the cyclic voltammetry aging as the non-power generation aging, the frequency of the sweep of the AC voltage applied to the fuel cell stack is set to a frequency within a predetermined range.

5. 2. The aging device according to claim 1, the aging unit performs at least cyclic voltammetry aging, as the non-power generation aging, in which a voltage applied to the fuel cell stack is repeatedly swept; An aging device, wherein when the aging unit performs cyclic voltammetry aging as the non-power generation aging, the proton resistance acquisition unit acquires the first proton resistance of the target cell when the voltage applied to the fuel cell stack is a predetermined voltage.

6. An aging method for aging a fuel cell stack having a plurality of cells, comprising: a non-power generation step of performing non-power generation aging on the fuel cell stack in a non-power generation state in which the fuel cell stack is not generating power by supplying hydrogen gas as an anode gas and an inert gas as a cathode gas; a first proton resistance acquisition step of acquiring, as a first proton resistance, a proton resistance of a target cell that is at least one of the cells of the fuel cell stack while the non-power generation aging is being performed on the fuel cell stack; a power generation step of supplying the hydrogen gas as the anode gas and the oxygen-containing gas as the cathode gas to the fuel cell stack to generate power, after the first proton resistance acquisition step; a power generation stopping step of stopping the power generation of the fuel cell stack by supplying the inert gas as the cathode gas after the power generation step; a second proton resistance acquisition step of acquiring, as a second proton resistance, the proton resistance of the target cell when the fuel cell stack is in the power generation stopped state; a third proton resistance acquisition unit that acquires a third proton resistance that is a value corresponding to a difference between the first proton resistance of the target cell and the second proton resistance of the target cell; The aging method comprises:

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