JP7417467B2 - How to activate a fuel cell stack - Google Patents

Description

This disclosure relates to a method for activating a fuel cell stack.

A fuel cell includes a membrane electrode gas diffusion layer assembly (MEGA) in which a catalyst layer containing a catalyst and a gas diffusion layer are joined to both sides of an electrolyte membrane. Separators each having a gas flow path are further arranged on both sides of the membrane electrode gas diffusion layer assembly. A fuel cell stack is constituted by stacking a plurality of fuel cells each including such a MEGA and a separator.

Manufactured fuel cell stacks may not be able to achieve sufficient performance as specified due to insufficient water content in the electrolyte membrane and the electrolyte in the catalyst layer, foreign matter adhering to the catalyst surface, oxidation of the catalyst, and the like. Therefore, it is necessary to age and activate the fuel cell stack by optimizing the water content in the electrolyte membrane and the electrolyte in the catalyst layer, removing foreign matter from the catalyst surface, and reducing the catalyst so that the fuel cell stack can achieve the specified performance. There is. This aging is proposed in Patent Document 1 below.

JP2016-35910A

In Patent Document 1, in order to remove impurity ions adsorbed on the catalyst surface, while supplying moisture to the membrane electrode gas diffusion layer assembly, the fuel is It has been proposed to maintain the power generation voltage of the battery stack below 0.3V. To perform this aging, it is necessary to flow a large current through the load in order to reduce the generated voltage to 0.3V or less.

On the other hand, as the load current increases, the generated current may decrease due to a decrease in oxygen concentration on the downstream side compared to the upstream side of the cathode to which air is supplied. Furthermore, as the load current increases, water generated by power generation may collect downstream of the cathode, and power generation capacity may decrease downstream.

As a result, the current density becomes uneven within the plane of the fuel cell, and a region where aging is not completed remains. Therefore, when aging a fuel cell, it is required to complete aging uniformly without causing in-plane unevenness in the fuel cell.

This disclosure has been made in view of the above problems, and aims to provide a method for activating a fuel cell stack that can uniformly age the inside of a fuel cell.

A method for activating a fuel cell stack according to this disclosure includes: a fuel cell stack in which fuel cells that are supplied with oxygen-containing air and hydrogen are stacked to generate electricity; a control unit that controls the state of the fuel cell stack; The control unit executes a first step of causing the fuel cell to generate power and supplying the generated power to a load, and a second step of stopping power generation of the fuel cell, and Set the air stoichiometric ratio on the side to a range that allows the hydrogen adsorption/desorption potential of the catalyst to be used , and adjust the amount of air and hydrogen supplied to the fuel cell stack so that the pressure on the anode side is higher than the pressure on the cathode side. Set the differential pressure between the electrodes so that

In the first step, the control unit causes the fuel cell stack to generate power so that the fuel cell generates a maximum current.
In the first step, the control unit sets the air stoichiometric ratio to 1.1 to 1.4.

The control unit sets the hydrogen stoichiometric ratio on the anode side not to become smaller than 1 in the first step.

The controller is equipped with a radiator that absorbs heat generated in the fuel cell with a cooling medium and releases the absorbed heat to the outside of the fuel cell. Control heat release.

The control unit further includes a temperature control unit that adjusts the temperature of the hydrogen and air, and the control unit adjusts the temperature of the hydrogen and air passing through the pipes that supply the fuel cell stack to be higher than the dew point temperature in the fuel cell. control.

According to the method for activating a fuel cell stack according to this disclosure, the interior of the fuel cell can be aged uniformly.

1 is a block diagram showing the configuration of a fuel cell system to which Embodiment 1 is applied. FIG. FIG. 2 is an explanatory diagram showing the configuration of a fuel cell and the current density during power generation in Embodiment 1. FIG. FIG. 2 is an explanatory diagram showing the configuration of a fuel cell and the current density during power generation in Embodiment 1. FIG. FIG. 2 is a characteristic diagram showing the characteristics of the hydrogen stoichiometric ratio and the standard deviation of current density on the anode side during aging of the fuel cell stack in Embodiment 1. FIG. 2 is a characteristic diagram showing the characteristics of the air stoichiometric ratio and the standard deviation of current density on the cathode side during aging of the fuel cell stack in the first embodiment. FIG. 2 is a characteristic diagram showing cell voltage and current characteristics during aging of the fuel cell stack in Embodiment 1. FIG. FIG. 2 is a characteristic diagram showing the characteristics of the anode inlet pressure and the standard deviation of current density during aging of the fuel cell stack in Embodiment 1. FIG. 2 is a characteristic diagram showing the characteristics of the cathode outlet pressure and the standard deviation of current density during aging of the fuel cell stack in Embodiment 1. FIG. 2 is a block diagram showing another configuration of the fuel cell system to which the first embodiment is applied.

Hereinafter, embodiments of a method for activating a fuel cell stack will be described with reference to the drawings. In addition, in each figure, the same parts are given the same reference numerals.

Embodiment 1.
First, the configuration of a fuel cell system 100 to which the method for activating a fuel cell stack in Embodiment 1 is applied will be described with reference to FIG. 1. FIG. 1 is a block diagram showing the configuration of a fuel cell system 100 to which the first embodiment is applied.

[Configuration of fuel cell system]
The fuel cell system 100 shown in FIG. It is equipped with The fuel cell stack 115 is provided with a measuring section 115s. The radiator 118 is provided with a measuring section 118s.

The control unit 101 controls the state of the fuel cell stack 115 by performing various controls related to power generation of the fuel cell system 100 and controlling when the fuel cell stack 115 is aged. Aging is the process by which the fuel cell stack 115 reaches its specifications by optimizing the water content in the electrolyte membrane and the electrolyte in the catalyst layer included in the fuel cells constituting the fuel cell stack 115, removing foreign matter from the catalyst surface, and reducing the catalyst. This refers to work that enables the performance of This aging is sometimes called activation processing.

The hydrogen tank 112 is filled with hydrogen. The filled hydrogen is supplied from the hydrogen tank 112 to the fuel cell stack 115 through the hydrogen supply valve 114. The hydrogen supply valve 114 is controlled by the control unit 101 to adjust the amount of hydrogen gas supplied from the hydrogen tank 112 to the fuel cell stack 115. Compressor 113 supplies air containing oxygen to fuel cell stack 115. The amount of air supplied from the compressor 113 to the fuel cell stack 115 is controlled by the control unit 101.

The fuel cell stack 115 has a stack structure in which a plurality of power generating fuel cells are stacked. In the fuel cell stack 115, each fuel cell generates power using hydrogen from the hydrogen tank 112 via the hydrogen supply valve 114 and oxygen contained in the air from the compressor 113 under the control of the control unit 101.

The DCDC converter 116 converts the power generation output of the fuel cell stack 115 into a constant voltage. For example, the DCDC converter 116 is a voltage converter attached to the output side of the fuel cell stack 115, and converts, for example, a voltage of about 80 volts to a voltage of about 48 volts or 12 volts and outputs the converted voltage.

The power storage device 117 is connected to the output of the DCDC converter 116 so that it can be charged, and discharges the charged current when a momentary large current flows in the load.

The radiator 118 absorbs heat generated by power generation by circulating the coolant circulation system of each fuel cell in the fuel cell stack 115, and releases the heat absorbed by the coolant to the outside of the fuel cell. It is a heat sink. The measurement unit 118s is a sensor that measures the temperature of the cooling medium passing through the radiator 118, and notifies the control unit 101 of the measurement result.

[Characteristics of fuel cell stack 115]
Here, the configuration and characteristics during power generation of the fuel cell 115C constituting the fuel cell stack 115 will be described with reference to FIGS. 2 and 3. 2 and 3 are explanatory diagrams showing the configuration of the fuel cell 115C and the current density during power generation in the first embodiment.

Here, the fuel cell 115C includes a power generation region 115C1, an air inlet 115C2, a hydrogen inlet 115C3, a hydrogen outlet 115C4, an air outlet 115C5, a coolant inlet 115C6, and a coolant outlet 115C7.

The fuel cell stack 115 described above generates power in the power generation region 115C1 having the membrane electrode gas diffusion layer assembly using oxygen contained in the air supplied from the air inlet 115C2 and hydrogen supplied from the hydrogen inlet 115C3. The remaining hydrogen that is not used for power generation is discharged from the hydrogen outlet 115C4. The remaining air that is not used for power generation is discharged from the air outlet 115C5 together with the generated water. Heat generated in the power generation region 115C1 during power generation is absorbed by the coolant flowing in from the coolant inlet 115C6 and flowing out from the coolant outlet 115C7. The heat absorbed by the cooling medium is released to the atmosphere at radiator 118.

In FIGS. 2 and 3, the shading assigned to the power generation region 115C1 indicates the current density during power generation in each region obtained by dividing the power generation region 115C1 into 8×8 regions, with darker areas having higher current densities. , and the thinner parts show lower current density.

FIG. 2 shows the current density distribution when power generation is performed at the maximum current specified by the fuel cell 115C. FIG. 3 shows the current density distribution when power generation is performed at 50% of the maximum current specified by the fuel cell 115C.

When the maximum current is generated as shown in FIG. 2, in the power generation region 115C1, a region with high current density is concentrated on the side near the air inlet 115C2, and a region with low current density is concentrated on the side near the air outlet 115C5. There is.

The reason why the current density deviation shown in FIG. 2 occurs is as follows. As the overall generated current increases, the oxygen concentration decreases on the side closer to the air outlet 115C5, which is downstream of the air flow, compared to the side closer to the air inlet 115C2 where air is supplied, and the generated current decreases. descend. Further, as the overall power generation current increases, water generated by power generation gathers on the air outlet 115C5 side, and the power generation capacity decreases because the water cannot be pushed out by the air flow rate. As a result, a region with high current density is concentrated on the air inlet 115C2 side, and a region with low current density is concentrated on the air outlet 115C5 side.

On the other hand, FIG. 3 shows the state of the power generation area 115C1 when power is generated at 50% of the specified maximum current, and the current density is not concentrated locally and is uniform over the entire surface without bias. A region exists. That is, in the fuel cell 115C, the power generation area 115C1 is used uniformly. Note that even when power is generated with a current that is not limited to 50% of the specified maximum current, and is smaller than the specified maximum current, the power generation region 115C1 becomes uniform over the entire surface without any bias in current density.

In the fuel cell system 100 that connects the output of the fuel cell stack 115 to the DCDC converter 116 to convert the voltage, the maximum current of the fuel cell 115C is not used due to the relationship between the voltages to be transformed and the characteristics of the DCDC converter 116. There are cases.

In this way, in the fuel cell system 100 in which the maximum current of the fuel cell 115C is not used, no aging effect can be expected due to use after shipment, so it is necessary to uniformly age the entire surface of the power generation region 115C1. In particular, in fuel cell systems used in industrial vehicles such as forklifts and stationary fuel cell generators, the maximum power consumption is lower than that in automobiles, so the maximum current specified by the fuel cell 115C is not used.

[Specific example of aging]
Hereinafter, as Embodiment 1, details of processing for uniformly aging the entire surface of the power generation region 115C1 of the fuel cell 115C will be described below. Note that aging in the first embodiment is performed by optimizing the water content in the membrane electrode gas diffusion layer assembly and the electrolyte in the catalyst layer included in the fuel cell 115C, removing foreign matter from the catalyst surface, reducing the catalyst, etc. This improves the initial performance of the stack 115.

(A) Power generation timing and stop timing:
The control unit 101 executes power generation timing as a first step and stop timing as a second step, as shown below. In this way, by performing the power generation timing as the first step and the stop timing as the second step, aging can be effectively performed. Here, by setting the power generation timing as the first step and the stop timing as the second step as one set, and repeating this one set a plurality of times, aging can be effectively performed in a short time.

(A1) Power generation timing:
The control unit 101 sets each unit of the fuel cell system 100 to provide a constant power generation timing of about 3 minutes during aging. Electric power generated by the fuel cell stack 115 is supplied to the load 300. Depending on the start-up characteristics of the compressor 113 and the response performance of the hydrogen supply valve 114, it is possible to set this certain period of time short.

(A2) Pause timing:
At the stop timing, the control unit 101 sets each part of the fuel cell system 100 so that power generation is stopped, there is no load, that is, the operation of the DCDC conversion unit 116 is stopped, and no current flows through the load 300. In other words, the control unit 101 sets the fuel cell 115C included in the fuel cell stack 115 to a voltage lower than the hydrogen adsorption/desorption potential of the catalyst at this pause timing. Then, at this pause timing, the water generated at the power generation timing is spread over the entire surface of the fuel cell 115C as much as possible. By doing so, the above-mentioned optimization of the water content and cleaning of foreign matter adhering to the catalyst can be effectively carried out. Therefore, a fixed pause timing of about 1 minute is provided after the power generation timing.

(B) Setting of generated current:
The control unit 101 controls the amount of water generated by power generation to be as large as possible at the above power generation timing (A1). This water optimizes the water content in the membrane electrode gas diffusion layer assembly and the electrolyte in the catalyst layer, and cleans foreign matter adhering to the catalyst. For this reason, it is desirable that the amount of water generated at the timing of power generation be as large as possible.

The amount of water generated per minute in the fuel cell stack 115 is W [g/min], the current generated and flowing in the fuel cell 115C is I [A], the Faraday constant is 96485 [C/mol, and the molar mass of water is When it is 18 [g/mol],
W [g/min] = I [A] / 96485 [C/mol] * Number of laminated sheets * 60 [sec] * 18 [g/mol]
The amount of water W to be generated can be determined as follows.
That is, since the amount of water W generated by power generation is proportional to the current I, the control unit 101 sets the current I at the above power generation timing (A1) to the maximum current of the specifications of the fuel cell 115C. This current is detected by the measuring section 115s. Thereby, at the power generation timing (A1), it is possible to generate water necessary for optimizing the water content in the membrane electrode gas diffusion layer assembly and the electrolyte in the catalyst layer, and for cleaning foreign matter adhering to the catalyst.

(C) Setting hydrogen stoichiometric ratio:
In this embodiment, the hydrogen stoichiometric ratio is the ratio between the amount of hydrogen to be supplied and the ideal amount of hydrogen required to generate electricity. Therefore, when the amount of hydrogen supplied is equal to the ideal amount of hydrogen required to generate electricity, the hydrogen stoichiometric ratio is 1. Furthermore, when the amount of hydrogen during power generation is greater than the ideal state, the hydrogen stoichiometric ratio becomes greater than 1.

The relationship between the hydrogen stoichiometric ratio and the variation in current density in each region within the fuel cell 115C will be described below with reference to FIG. 4. FIG. 4 is a characteristic diagram showing the characteristics of the hydrogen stoichiometric ratio and the standard deviation of current density on the anode side during aging of the fuel cell stack 115 in the first embodiment. Here, the standard deviation of the current density on the vertical axis in FIG. 4 indicates the variation in current density during power generation in each region obtained by dividing the power generation region 115C1 of the fuel cell 115C into 8×8 regions.

According to FIG. 4, even when the value of the hydrogen stoichiometric ratio is changed within a range greater than 1, the standard deviation of the current density in each region within the fuel cell 115C hardly changes. Therefore, since the hydrogen stoichiometric ratio has no effect on variations in current density, at the above power generation timing (A1), set the hydrogen stoichiometric ratio to a value greater than 1, or prevent the hydrogen stoichiometric ratio from becoming a value smaller than 1. , the control unit 101 controls the hydrogen supply valve 114 to set the amount of hydrogen. By setting the hydrogen stoichiometric ratio in this way, the catalyst used in the fuel cell 115C is reduced by hydrogen that is not used for power generation.
Further, the control unit 101 controls the hydrogen supply valve 114 to set the flow rate of hydrogen so that the pressure on the anode side is higher than the pressure on the cathode side in the interelectrode pressure difference described later.

(D) Setting of air stoichiometric ratio:
In this embodiment, the air stoichiometric ratio is the ratio between the amount of supplied air and the ideal amount of air required to generate electricity. Therefore, when the amount of air supplied is equal to the ideal amount of air required to generate electricity, the air stoichiometric ratio is 1. Further, when the amount of air during power generation is larger than the ideal state, the air stoichiometric ratio becomes larger than 1.

The relationship between the air stoichiometric ratio and the variation in current density in each region within the fuel cell 115C will be described below with reference to FIG. FIG. 5 is a characteristic diagram showing the characteristics of the air stoichiometric ratio and the standard deviation of current density on the cathode side during aging of the fuel cell stack 115 in the first embodiment. Here, the standard deviation of the current density on the vertical axis in FIG. 5 indicates the variation in current density during power generation in each region obtained by dividing the power generation region 115C1 of the fuel cell 115C into 8×8 regions.

According to FIG. 5, it can be seen that when the value of the air stoichiometric ratio is increased, the standard deviation of the current density in each region within the fuel cell 115C becomes smaller, and the variation in current density becomes smaller. On the other hand, it is known to utilize the hydrogen adsorption/desorption potential of a catalyst to remove foreign matter from the catalyst surface, which is one of the effects of aging. The hydrogen adsorption/desorption potential will be explained with reference to FIG. FIG. 6 is a characteristic diagram showing the cell voltage and current characteristics of the fuel cell 115C during aging in the first embodiment. A range in which the cell voltage of the fuel cell 115C is about 0.1V to 0.4V is the hydrogen adsorption/desorption potential. In order to lower the voltage to the region of this hydrogen adsorption/desorption potential, it is conceivable to set the air stoichiometric ratio on the cathode side low and to generate electricity in the fuel cell 115C in an oxygen-deficient state so that hydrogen remains. This makes it possible to reduce the oxidized catalyst with hydrogen, which is one of the effects of aging.

However, when the air stoichiometric ratio is set low in this way, the amount of oxygen that should be combined with hydrogen decreases near the air outlet 115C5 of the fuel cell 115C, and a power generation failure region with low current density occurs in the power generation region 115C1. Therefore, the control unit 101 controls the compressor 113 to adjust the amount of air so that the air stoichiometric ratio on the cathode side at the power generation timing (A1) is set within a range where the hydrogen adsorption/desorption potential of the catalyst can be used. . More specifically, the control unit 101 sets the air stoichiometric ratio to an extent that does not cause an excessive oxygen deficiency state in the power generation region 115C1 of the fuel cell 115C, for example, about 1.1 to 1.4, preferably 1.3. Set to a certain degree.

Another method for setting the value of the air stoichiometric ratio in this way is to use a mixed gas with a lower oxygen concentration than actual air. By using a mixed gas with a low oxygen concentration in this way, it is possible to utilize the hydrogen adsorption/desorption potential of the catalyst while maintaining the force to push the generated water to the air outlet 115C5 without reducing the flow rate of the mixed gas. The state can be maintained. For example, setting the air stoichiometric ratio to 1.1 maintains the hydrogen adsorption/desorption potential of the catalyst in a usable state, and achieves the same air flow rate as setting the air stoichiometric ratio to 1.3. If there is, if the oxygen concentration of the actual air is 0.209,
Oxygen concentration = 1.1 * 0.209/1.3 = 17.7 [%]
It is sufficient to prepare a mixed gas whose oxygen concentration is adjusted so that

(E) Setting the anode inlet pressure:
The variation in current density when the pressure of the hydrogen inlet 115C3 as an anode inlet in the fuel cell 115C is adjusted will be explained using FIG. 7. FIG. 7 is a characteristic diagram showing the characteristics of the hydrogen inlet pressure and the standard deviation of current density during aging of the fuel cell stack 115 in the first embodiment. Here, the standard deviation of the current density on the vertical axis in FIG. 7 indicates the variation in current density during power generation in each region obtained by dividing the power generation region 115C1 of the fuel cell 115C into 8×8 regions. The control unit 101 sets the current I at the above power generation timing (A1) to the maximum current according to the specifications of the fuel cell 115C, and the pressure at the hydrogen inlet 115C3 can reach an operating point exceeding, for example, 200 kPaA. Then, since such pressure does not have a large effect on the variation in current density, the control unit 101 controls the hydrogen supply valve 114 to adjust the hydrogen pressure on the entire surface of the fuel cell 115C, and controls the hydrogen pressure on the anode side. The differential pressure between the electrodes is set so that the pressure is greater than the pressure on the cathode side. As a result, the pressure of hydrogen on the anode side increases, so that reduction of the oxidized catalyst, which is one of the effects of aging, can be appropriately achieved.

(F) Setting the cathode outlet pressure:
The variation in current density when adjusting the pressure of the air outlet 115C5 as a cathode outlet in the fuel cell 115C will be explained using FIG. 8. FIG. 8 is a characteristic diagram showing the characteristics of the air outlet pressure and the standard deviation of current density during aging of the fuel cell stack 115 in the first embodiment. Here, the standard deviation of the current density on the vertical axis in FIG. 8 indicates the variation in current density during power generation in each region obtained by dividing the power generation region 115C1 of the fuel cell 115C into 8×8 regions. In this way, as the pressure at the air outlet 115C5 increases, the standard deviation of the current density tends to decrease, and variations in the current density are suppressed. According to the characteristics shown in FIG. 7, it is desirable that the pressure at the air outlet 115C5 be as high as possible, but in the aging of the first embodiment, it is desirable to be able to reduce the oxidized catalyst with hydrogen. Therefore, at the above power generation timing (A1), the control unit 101 controls the compressor 113 to adjust the amount of air on the entire surface of the fuel cell 115C, so that the pressure on the cathode side is lower than the pressure on the anode side. Set the differential pressure between the electrodes as follows. As a result, the pressure of hydrogen on the anode side increases, so that reduction of the oxidized catalyst, which is one of the effects of aging, can be appropriately achieved.

(G) Coolant temperature setting:
Generally, the higher the temperature of the cooling medium flowing within the fuel cell stack 115, the more active the catalyst of the membrane electrode gas diffusion layer assembly becomes, and as a result, the aging is more effective. However, if the temperature of the cooling medium is high, there is a risk that the membrane electrode gas diffusion layer assembly may dry out. Therefore, during aging, the temperature of the cooling medium at the cooling medium inlet 115C6 is set to 70°C or 65°C so that the maximum temperature of the power generation region 115C1 of the fuel cell 115C does not exceed a set value, for example, 90°C. . The control unit 101 refers to the measurement result of the measurement unit 118s, switches on/off the fan of the radiator 118, and controls the release of heat from the cooling medium so as to satisfy the above set value. By doing so, the moisture content of the membrane electrode gas diffusion layer assembly can be optimized and the catalyst can be highly activated.

(H) Gas temperature/dew point temperature setting:
Another configuration of the fuel cell system 100 to which the method for activating the fuel cell stack 115 in Embodiment 1 is applied will be described with reference to FIG. 9. FIG. 9 is a block diagram showing another configuration of the fuel cell system 100 to which the first embodiment is applied. In FIG. 9, parts that are the same as those in FIG. 1 are given the same reference numerals to omit redundant explanation, and only different parts will be explained. In the fuel cell system 100 in FIG. 9, the temperature of hydrogen supplied from the hydrogen tank 112 to the fuel cell stack 115 via the hydrogen supply valve 114 and the air supplied from the compressor 113 to the fuel cell stack 115 is adjusted. A temperature control section 119 is provided.

From the viewpoint of humidifying the membrane electrode gas diffusion layer assembly at the above power generation timing (A1), it is desirable that the dew point temperature in the fuel cell 115C is as high as possible. On the other hand, hydrogen or air at the dew point temperature may cause condensation within the pipes. Accordingly, in order to prevent hydrogen or air at the dew point temperature from condensing in the piping, the control unit 101 controls the temperature control unit 119 so that the temperature of the hydrogen and air is higher than the dew point temperature, for example. Set the dew point temperature above +4℃. By doing so, the membrane electrode gas diffusion layer assembly can be appropriately humidified.

[Effects obtained by the embodiment]
By executing each of the processes (A) to (H) described above in Embodiment 1, the fuel cell 115C included in the fuel cell stack 115 can be more effectively removed from the fuel cell stack 115 in a short time. It is possible to optimize the moisture content of the electrolyte membrane necessary for proton conduction in the membrane electrode gas diffusion layer assembly, reduce the oxidized catalyst, and perform aging by removing and cleaning foreign matter attached to the catalyst. Furthermore, by performing the aging of the first embodiment before shipping the fuel cell system 100, even if the fuel cell system 100 does not use the maximum current of the fuel cell 115C, it is possible to Since aging of the fuel cell stack 115 can be completed, the durability of the fuel cell stack 115 can be improved. Therefore, the fuel cell stack 115 can be activated.

That is, the effects obtained by the first embodiment are as follows.
(1) The control unit 101 executes a power generation timing for causing the fuel cell 115C to generate power and supplying the generated power to the load 300, and a suspension timing for stopping power generation of the fuel cell 115C, and at the power generation timing. , the air stoichiometric ratio on the cathode side is set within a range that allows the hydrogen adsorption/desorption potential of the catalyst to be utilized. Thereby, at the timing of power generation, it is possible to generate water necessary for optimizing the water content in the membrane electrode gas diffusion layer assembly and the electrolyte in the catalyst layer, and for cleaning foreign matter adhering to the catalyst. Then, the water generated at the power generation timing can be spread over the entire surface of the fuel cell 115C as much as possible at the stop timing. By doing so, the above-mentioned optimization of the water content and cleaning of foreign matter adhering to the catalyst can be effectively carried out. Furthermore, the amount of air and hydrogen supplied to the fuel cell stack is adjusted, and the differential pressure between the electrodes is set so that the pressure on the anode side is greater than the pressure on the cathode side. This increases the pressure of hydrogen on the anode side, making it possible to appropriately reduce the oxidizing catalyst with hydrogen.

(2) The control unit 101 causes the fuel cell 115C to generate power so that it generates the maximum current at the power generation timing. This makes it possible to generate a sufficient amount of water necessary for optimizing the water content and cleaning foreign matter.

(3) The control unit sets the air stoichiometric ratio to 1.1 to 1.4 at the power generation timing. By setting the air stoichiometric ratio low in this way, hydrogen will remain even when power is generated, making it possible to reduce the oxidized catalyst with hydrogen.

( 4 ) The control unit 101 sets the hydrogen stoichiometric ratio on the anode side so that it does not become smaller than 1 at the power generation timing. By setting the hydrogen stoichiometric ratio in this manner, there is hydrogen that is not used for power generation, and reduction of the oxidizing catalyst with hydrogen can be achieved.

( 5 ) The control unit 101 controls the release of heat from the cooling medium in the radiator 118 so that the temperature of the fuel cell 115C does not exceed a set value. By this control, in the fuel cell 115C, it is possible to optimize the water content of the membrane electrode gas diffusion layer assembly while highly activating the catalyst.

( 6 ) The control unit 101 controls the temperature adjustment unit 119 so that the temperature of the hydrogen and air supplied to the fuel cell stack 115 through the pipes is higher than the dew point temperature of the fuel cell 115C. With this control, the membrane electrode gas diffusion layer assembly can be appropriately humidified.

[Other embodiments]
In the above description of the first embodiment, aging is executed under the control of the control unit 101, but the present invention is not limited to this, and for example, an external control device may execute the aging through the control unit 101. In this case, the external control device or the external control device and control unit 101 operates as a control unit that controls aging of the fuel cell system 100.

In order to realize the current I of the fuel cell 115C set by the control unit 101 in (B) above, the load 300 may be configured with a variable resistor. Further, during aging, the output of the fuel cell stack 115 and the load 300 may be directly connected without passing through the DCDC converter 116.

When carrying out the method for activating the fuel cell stack 115 of the first embodiment described above, it has been described that the fuel cell stack 115 is aged under the control of the control unit 101 within the fuel cell system 100, but the present invention is not limited to this. It's not a thing. That is, when aging the fuel cell stack 115, the fuel cell stack 115 and various devices or devices other than the fuel cell stack 115 that are connected to the fuel cell stack 115 are not necessarily the same as the fuel cell system 100. Does not need to be configured. For example, the fuel cell stack 115 may be aged using dedicated equipment for aging the fuel cell stack 115. Specifically, before the manufactured fuel cell stack 115 is assembled into the fuel cell system 100, the fuel cell stack 115 is aged using dedicated equipment equipped with a control unit and load capable of aging. Then, the fuel cell stack 115 that has been aged using dedicated equipment as a pre-process is assembled into the fuel cell system 100 as a post-process.

100 fuel cell system, 101 control unit, 112 hydrogen tank, 113 compressor, 114 hydrogen supply valve, 115 fuel cell stack, 115s measurement unit, 115C fuel cell, 115C1 power generation area, 115C2 air inlet, 115C3 hydrogen inlet, 115C4 hydrogen outlet , 115C5 air outlet, 115C6 coolant inlet, 115C7 coolant outlet, 116 DCDC conversion unit, 117 power storage device, 118 radiator, 118s measurement unit, 119 temperature control unit.

Claims (6)

A fuel cell stack in which fuel cells that are supplied with oxygen-containing air and hydrogen to generate electricity are stacked, and a control unit that controls the state of the fuel cell stack,
The control unit includes:
A first step of causing the fuel cell to generate electricity and supplying the generated electricity to a load;
a second step of suspending power generation of the fuel cell;
Run
The air stoichiometric ratio on the cathode side in the first step is set in a range that allows the hydrogen adsorption and desorption potential of the catalyst to be used ,
A method for activating a fuel cell stack, comprising adjusting the amount of air and the amount of hydrogen supplied to the fuel cell stack, and setting a differential pressure between the electrodes so that the pressure on the anode side is greater than the pressure on the cathode side . The method for activating a fuel cell stack according to claim 1, wherein in the first step, the control unit causes the fuel cell to generate power so as to generate a maximum current. 3. The method for activating a fuel cell stack according to claim 1, wherein the control unit sets the air stoichiometric ratio to 1.1 to 1.4 in the first step. The method for activating a fuel cell stack according to any one of claims 1 to 3 , wherein the control unit sets the hydrogen stoichiometric ratio on the anode side not to become smaller than 1 in the first step. A radiator that absorbs heat generated in the fuel cell with a cooling medium and releases the absorbed heat to the outside of the fuel cell,
The activation of the fuel cell stack according to any one of claims 1 to 4 , wherein the control unit controls the release of the heat in the radiator so that the temperature of the fuel cell does not exceed a set value. method. further comprising a temperature control unit that adjusts the temperature of the hydrogen and the air,
The control unit controls the temperature adjustment unit so that the temperature of the hydrogen and the air that are supplied to the fuel cell stack through piping is higher than the dew point temperature in the fuel cell. 6. The method for activating a fuel cell stack according to claim 5 .

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